Low Temperature Cure Dye Resist Processes for Wool

LOW TEMPERATURE CURE DYE RESIST

PROCESSES FOR WOOL

A THESIS SUBMITTED TO

THE UNIVERSITY OF NEW SOUTH WALES

FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

by

BYONG DAE JEON

SCHOOL OF FIBRE SCIENCE AND TECHNOLOGY

THE UNIVERSITY OF NEW SOUTH WALES

1992 DECLARATION

I hereby declare that this submission is my own work and that, to the best of my knowledge and belie� it contains no material previously published or written by another person nor material which to a substantial extent has been accepted for the award of any other degree or diploma of a university or other institute of higher learning, except where due acknowledgement is made in the text.

(ii) ACKNOWLEDGEMENTS

The author wishes to sincerely thank the following:-

Associate Professor M. T. Pailthorpe for bis invaluable guidance and supervision throughout the course of this thesis.

Dr. S. David for her advice and co-supervision during this project.

Other members of the staff and students of the School of Fibre Science and Technology for their assistance in many ways.

The Australian Wool Corporation for the award of a postgraduate research scholarship.

Professor Hwan Cho, the author's mentor in Korea, for bis encouragement during this project.

His family, especially bis wife, Jusoo Han, for their patience and support throughout the course of bis studies.

(iii) ABSTRACT

Patterned effects can be achieved by either discharge or dye resist processes. The dye resist methods have more advantages than discharge processes.

The aim of this project was to develop new and improved methods for the preparation, application and curing of dye resist agents on wool to achieve a dye resist effect at low temperature and to elucidate the mechanisms of the dye resist effect.

Dye resist effects achieved on sulphamic acid treated wool were investigated in respect of curing temperature and dyestuff type. It was found that there is a significant difference between the pH of aqueous extracts from lOQ<>C, 125°C and 15Q<>C cured sulphamic acid treated wool. The results from dye exhaustion studies indicate that, for curing temperatures less than 14Q<>C, unbound free sulphamic acid is desorbed from the wool. The desorbed sulphamic acid then changes dyebath pH which, in tum, changes the resist effect achieved. Only when the sulphamic acid is cured above 14Q<>C does complete reaction/pyrolysis of the sulphamic acid take place giving the best dye resist effect.

(iv) Overall it appears that the dye resist effect is highly dependent on the hydrophilic/hydrophobic character of the dyestuffs and substrate. It is demonstrated in this thesis that the IOR values of the dyes can be used to quantify dye resist effects on sulphamic acid treated wool.

Four reactive dye resist agents were synthesised and characterised The orders of dye resist effects are consistent with the IOR values of the dyes which dye by ionic/hydrophobic dyeing mechanisms.

The results indicate that low temperature curing can be applied to produce tone on tone effects or dark colour resist treatments in the case of bifunctional reactive resists.

The dye resist effects of bifunctional groups are superior to those of monofunctional groups, especially in competition dyeing. The causes of these effects might be that there are crosslinking effects between bifunctional groups and the wool substrate, and these bifunctional groups play a shielding role together with other repulsion forces.

Sulphamic acid treated wool shows excellent stain blocking effects. The stain blocking effect of the ORB treated wool is significantly better than the ORM treated wool. It must be noted however, that there is slight staining in the case of ORB treated wool and it is only at 80 % stain

(v) resist value and above that the sample exhibits no noticeable staining visually. Therefore ORB treated wool also needs more improvement of its stain blocking effect.

Full white resists effects seem to be very difficult for reactive resists to achieve. The sulphamic acid resist process remains the best dye resist technique. Although for normal dyeing (not for competition dyeing), the reactive resists synthesised in this project were not fully successful, the author still believes that the concept of a bifunctional group is worthy of further study. If higher levels of fixation and crosslinking effects could be achieved, the perfect dye resist process may still be feasible.

(vi) UST OF ABBREVIATIONS AND SYMBOLS

ANDA 1-Amino-8-Naphthol-3,6-Disulphonic Acid Ar Aryl Group C Competition Dyeing Ch Chemical Type of Dye Resist Method Cl Colour Index CP Charged Polar CPD Compound d Dyed DCCA Dichloro-Isocyanuric Acid Sodium Salt DMF Dimethylformamide Dr Dye Resist Group DRB 2,5-Bis(2,4-dichloro-s-triazin-6-yl)-Aminophenyl- Sulphonic Acid Sodium Salt DRM 2,4-Dichloro-s-triazin-6-yl-p-Aminophenyl-Sulphonic Acid Sodium Salt DRN 2,4-Dichloro-s-triazin-6-yl-Amino-8-Naphthol-3,6- Disulphonic Acid Sodium Salt DRS 2,4-Dichloro-s-triazin-6-yl-p-Aminosalicylic Acid Sodium Salt Eo Optical Density at time 0 E. Optical Density at time t Es Exhaustion % of Sample FDNB 1-Fluoro-2,4-dinitrobenzene HLB Hydrophile-Lipophile Balance IOR Inorganicity-Organicity Ratio

(vii) IR Infrared K Absorption Coefficient K/S Ratio of K to S MW Molecular Weight N Normal Dyeing NP Non-polar Ph Physical Type of Dye Resist Method QSAR Formulation of Quantitative Structure Activity Relationships Resist Reflectance of the Fabric at the Wave Length of Maximum Absorption RN Resist Number s Scattering Coefficient SA Sulphamic Acid SIO Sum of Inorganicity Value so Sum of Organicity Value SR Stain Resist Effect ( % ) THPC Tetrakis Hydroxymethyl Phosphonium Chloride TLC Thin Layer Chromatography TNBS Trinitrobenzene Sulphonic Acid tr Treated Wool u Unmodified ud Undyed ut Untreated Wool UP Uncharged Polar UV Ultraviolet WG Weight Gain X Reactive Group

(viii) TABLE OF CONTENTS

Declaration ...... (ii) Acknowledgements ...... • ...... (iii)

Abstract ...... (iv)

List of Abbreviations and Symbols ...... (vii)

CHAPTER 1. INTRODUCTION ...... 1 1.1. Preamble ...... 1

1.2. The Chemistry of Wool ...... 3

1.2.1. Amino Acid Composition of Wool ...... 3 1.2.1.1. Nonpolar Side Chains ...... 4 1.2.1.2. Uncharged Polar Side Chains . . . . . 5 1.2.1.3. Charged Polar Side Chains ...... 5

1.2.2. Reactivity of Wool 6

1.2.2.1. Oxidation 7

1.2.2.2. Reduction 8

1.2.2.3. Hydrolysis ...... 8

1.2.2.4. Sulphation ...... 10

1.2.2.s. Acylation ...... 11

1.2.2.6. Alkylation ...... 12

(ix) 1.2.2. 7. Arylation ...... 13 1.2.2. 7.1. 1-Fluoro-2,4- dinitrobenzene (FDNB) . . . . . 13 1.2.2. 7.2. Trinitro Benzene Sulphonic Acid (TNBS) 14 1.2.2.7.3. Cyanuric Halides and Derivatives ...... 14 1.2.2.8. Esterification ...... 15 1.2.3. Reactive Groups for Wool ...... 15 1.2.3.1. Reactive Dyes with a Chloroacetamide group ...... 16 1.2.3.2. Reactive Dyes with a Chlorotriazine group ...... 17 1.2.3.3. Reactive Dyes with a ChlorodiOuoropyrimidine group . . . . 17 1.2.3.4. Reactive dyes with a •- Bromoacrylamido group ...... 18 1.2.3.5. Reactive Dyes with a N­ methyltaurine-ethylsulphonyl group . 18 1.2.3.6. Reactive dyes with Bifunctional groups ...... 19 1.2.4. Binding Sites of Wool ...... 19 1.2.5. Dyeing of Wool ...... 21 1.2.5.1. Ionic links or Salt formation ...... 22 1.2.5.2. van der Waals' Forces and other

(x) dipole interactions ...... 22 1.2.5.3. Hydrophobic Interactions ...... 22 1.2.5.4. Covalent Bonds ...... 23 1.2.5.5. The Role of Binding Forces in Dyeing and Printing ...... 23 1.3. Resist Processes ...... 24 1.3.1. Coating Method ...... 25 1.3.2. Tannic Acid ...... 26 1.3.3. Acetylation ...... 27 1.3.4. Glyoxal Bis Sodium Bisulphite ...... 28 1.3.5. Naphtholsulphonic Acid Salts with Formaldehyde ...... 28 1.3.6. Magnesium Bromoacetate ...... 29 1.3. 7. Synthetic Polymers ...... 30 1.3.8. Alkaline or Neutral Chlorination ...... 30 1.3.9. Oxidation by Periodic acid ...... 31 1.3.10. Sulphation with concentrated sulphuric acid ...... 32 1.3.11. Synthetic tannic agents ...... 33 1.3.12. Irradiation with UV or y Rays ...... 34 1.3.13. Sulphamic acid ...... 34 1.3.14. Reactive resist ...... 35 1.4. Methods for the assessment of the dye resist effect . . . 36 1.4.1. Resist Number (RN) ...... 3 7

(xi) 1.4.2. Percentage Resist Value ...... 37

1.4.3. Dye Absorption method ...... 39

1.5. Low Temperature Dyeing of Wool ...... 39

1.5.1. Organic Solvent Method ...... 39

1.5.2. Formic Acid Method ...... 40

1.5.3. Amine Pretreatment Method ...... 40

1.5.4. Surfactant or Auxiliary Addition Method . . . 41

1.5.5. Cold Pad Batch Process ...... 41

1.6. The Aim of This Project ...... 42

1.6.1. The Requirements of a Low Temperature

Curable Reactive Resist ...... 43

1.6.2. Approach of the Present Work ...... 43

CHAPTER 2. DYE RESIST EFFECTS ON

SULPHAMIC ACID TREATED WOOL 45

2.1. Introduction ...... 45

2.2. Dye Resist Effects on Sulphamic Acid Treated Wool . 46

2.2.1. Materials and Methods ...... 46

2.2.1.1. Fabric ...... 47

2.2.1.2. Dyes ...... 4 7

2.2.1.2.1. Dye Structures ...... 47

2.2.1.2.2. Purification of Dyes ...... 4 7

2.2.2. Application of Sulphamic Acid to Wool . . . . . 48

2.2.2.1. Application of Sulphamic Acid . . . . . 48

(xii) 2.2.2.2. Dyeing Methods ...... 48

2.2.2.3. Dye Exhaustion Curve ...... 5 O 2.2.2.4. Determination of pH of the Aqueous Extract of Sulphamic Acid treated Wool ...... 51

2.2.2.5. Dye Resist Evaluation ...... 53

2.2.3. Results and Discussion ...... 53

2.2.3.1. Optimum Curing Temperature . . . . 53 2.2.3.2. The pH Variation of Sulphamic Acid treated Wool at Different

Curing Temperatures ...... 54

2.2.3.3. Dye Exhaustion Curves ...... 55 2.2.3.4. The Influence of Sulphonic Acid Groups ...... 59 2.2.3.5. Quantification of the Relationship of Dye, Water, Substrate...... 61

2.2.3.5.1. HLB Method ...... 62

2.2.3.5.2. IOR Method ...... 62

2.2.3.5.3. QSAR Method ...... 63

2.3. Conclusions ...... 65

CHAPTER 3. PREPARATION AND APPLICATION OF REACTIVE DYE RESIST AGENTS ...... 67 3.1. Introduction ...... 67 3.2. Preparation and Application of s-Triazine based

(xiii) Reactive Resists ...... 69 3.2.1. Materials and Methods ...... 69 3.2.1.1. Materials ...... 69 3.2.1.2. Dyes ...... 69 3.2.1.3. Purification of Chemicals ...... 70 3.2.1.4. Synthesis of 2,4-Dichloro-s-triazin-6-yl-p-aminop henyl- sulphonic acid sodium salt

(dihydrate) (DRM) ...... 72 3.2.1.5. Synthesis of 2,5-Bis(2,4-dichloro-s-triazin-6-yl)­ aminophenyl-sulphonic acid sodium

salt (dihydrate) (DRB) ...... 72 3.2.1.6. Synthesis of 2,4-Dichloro-s-triazin- 6-yl-p-aminosalicylic Acid Sodium

Salt (Dihydrate) (DRS) ...... 73 3.2.1.7. Synthesis of 2,4-Dichloro-s-triazin- 6-yl-amino-8-naphthol-3,6- disulphonic Acid Sodium Salt

(DRN) ...... 73 3.2.1.8. Characterisation of Products ...... 74 3.2.1.9. Application of Resist Compounds . . 74 3.2.1.10. Determination of Weight Gain . . . . 76 3.2.1.11. Dyeing of Wool Fabric ...... 76 3.2.1.12. Evaluation of Dye Resist Effect 76

(xiv) 3.3. Results and Discussion ...... 77 3.3.1. Synthesis ...... 77 3.3.2. Characterisation of Products ...... 77

3.3.3. Weight Gain ...... 78 3.3.4. Dye Resist Effects ...... 81 3.3.5. Another Example of IOR Values ...... 86 3.4. Conclusions ...... 88

CHAPTER 4. Stain Blocking Effects of Dye Resist Agents ...... 90 4.1. lntn>duction ...... 90 4.2. Materials and Methods ...... 90 4.2.1. Materials ...... 91 4.2.2. DCCA Treatment ...... 91 4.2.3. Application of Reactive Resists ...... 91 4.2.4. Sulphamation of Wool ...... 92 4.2.5. Staining Method ...... 92

4.2.6. Determination of Stain Blocking Effects . . . . 93 4.3. Results and Discussion ...... 93 4.3.1. Exhaustion Curves in Stain Resist Test . . . . . 93 4.3.2. Stain Blocking Effects ...... 94

4.4. Conclusions ...... 96

CHAPTER 5. CONCLUSIONS ...... 97

(xv) Bibliography ...... 100 Appendices

- Appendix I. Calculation of /OR Values ...... 113

- Appendix II. JR. Spectra of Reactive Resists ...... 123

- Appendix III. /OR Values of Cl Food Red 17 and Cl Acid Green 25 ...... 127 - Appendix w. The Reflectance Curves of the SR treated Wool ...... 129

(xvi) CHAPTER 1. INTRODUCTION

1.1. Preamble

Tone-on-tone effects, white or coloured patterns on contrasting ground shades in textile dyeing and printing, have become more popular as people have come to regard these aesthetic aspects as highly desirable. The patterned effects produced can be achieved by either discharge or resist processes. In a discharge process, the fabric is dyed first and then the pattern is obtained by printing with a discharging agent that destroys the dye in the printed area. In resist printing the fabric is first printed with a resist agent and then dyed.

Conventionally, patterned effects have been mainly achieved by discharge methods. However, textile materials are easily damaged during treatment by discharge methods because of the necessity to utilise strong oxidising or reducing agents. This adversely affects physical properties such as handle or tensile strength. Another drawback of the discharge method is the high cost of treatment. Usually the discharge treatment is conducted after dyeing or printing in contrast to resist processes, in which the treatment is normally before dyeing. Hence resist methods can potentially save more energy and chemicals than discharge methods. Above all, however, the advantage of resist methods lies in the more diverse application of dyestuffs. There are dyestuffs which are classified as "not dischargeable" or having "poor dischargeability" in the Colour

1 Chapter 1 Introduction

Index. These kinds of dyestuffs can not be used in discharging methods, but they can be applied in dye resist methods.

A dye resist process is one in which the dye uptake is slower or less than that on the untreated substrate, and can be obtained by either physical methods or chemical modification of the substrate which is to be resist printed. These processes have been applied and developed in numerous ways in the case of cellulosic textiles [1,2,3]. However, at present, there is no process for wool that is entirely satisfactory for reasons of high cost, complicated processing and/or the poor resist achieved [4,5]. Although many researchers [2,6] accept the merits of the dye resist method, which has a potentially less damaging effect on the wool fibre, the process has not been systematically studied.

The use of sulphamic acid as a dye resist agent was first introduced by Sandoz [7] but attracted little attention. It is known that this reagent provides by far the best dye resist effect [8], although the commercial viability of the process is limited by the very high temperature (150- 200" C) required for curing. Therefore, the need still exists for a low temperature curable process for wool which will allow resist dyeing and printing.

The aim of the present work is to develop new and improved methods for the preparation, application and curing of dye resist agents on wool

2 Chapter 1 Introduction

to achieve the dye resist effect at low temperature and to elucidate the

mechanisms of the dye resist effect.

Although dye resist effects restrict dye uptake and are therefore the reverse of dyeing processes in that respect, the mechanisms involved in dye resist processes nevertheless have a strong correlation with those of dyeing processes. Therefore it is worth studying dye resist processes in order not only to develop an improved dye resist method, but also to contribute to the understanding of dyeing technology. Furthermore, resist processes have enormous potential to be developed and applied in other areas such as in stain blocking technology or for the purpose of various reactive fixing processes.

1.2. The Chemistry of Wool

As most of the experimental work described in this project involves the reactions of the wool fibre, it is appropriate that the present state of knowledge of the chemistry of wool be reviewed Detailed knowledge of the reactions of wool is necessary in order to understand the chemical mechanisms of existing dyeing and dye-resist processes and to develop new methods directed towards the chemical modification of wool.

1.2.1. Amino Acid Composition of Wool

3 Chapter 1 Introduction

Structure Iso- Amino Acid of Side Chain MW % Polarity electric (-R) Point

Aspartic -CH2COOH 133.10 6.7 CP 2.77 Acid

Glutamic -CH2CH2C02H 147.13 15.0 CP 3.22 Acid

Lysine -(CH2hCH2NH2 146.19 2.8 CP 9.59

NH II Arginine -(CH2hNHC 174.21 10.5 CP 10.76 \ NH2

CH-NH // Histidine -CH2-C 155.16 0.9 UP 7.59 \ I N=CH

Cystine -CH2-S-S-CH2 240.30 11.3 UP 5.03

Methionine -CH2CH2SCH3 149.29 0.6 NP 5.74 . CH;-CH2 I I Praline ~2/CHCOOH 115.13 7.3 NP 6.30 NII

Tryptophan -CH,w 204.22 2.1 NP 5.89 I H

Cont'd Table 1.1. ci-Amino Acids Composition of Wool Chapter 1 Introduction

Iso- Structure of ** Amino electric Side Chain * % Polarity Acid MW Point (-R) [10] [11]

Glycine -H 75.07 5.2 NP 5.97

Alanine -CH3 85.09 3.7 NP 6.00

Valine -CH(CH3)2 117.15 5.0 NP 5.96

Leucine -CH2CH(CH3)2 131.17 7.6 NP 5.98

Isoleucine -CH(CH3)CH2CH3 131.17 3.1 NP 5.94

Phenyl- 165.19 3.4 NP 5.48 alanine -CH1-@

Serine -CH2OH 106.09 9.0 UP 5.68

Threonine -CH(CH3)OH 119.12 6.6 UP 5.64

Tyrosine -CH1·©0H 181.19 6.4 UP 5.66

* MW Molecular Weight ** NP Non Polar UP Uncharged Polar CP Charged Polar

Table 1.1. «-Amino Acids Composition of Wool (Cont'd) Chapter 1 Introduction

R

H l - Hj+/f\c10 I H ll H 0

General Formula ZWitterion

Figure 1.1. General Formula for an amino acid

R H H I - H I c. o I H+ OH I H3Ntc-eooH H-N 1/'1"" C l H N-e-eoo- - H I: - I I 2 I R 0 H R Acidic condition Zwitterion Alkaline condition

Figure 1.2. Amphoteric Character of Amino Acids Chapter 1 Introduction

Wool is a type of albuminoid protein known as keratin [9]. The monomer units from which this protein is derived are a-amino acids. Variation in the structures of these amino acids occurs in the side chains. Under conditions of neutral pH, an amino acid undergoes an internal acid-base reaction to produce a dipolar ion, sometimes called a zwitterion (Figure 1. 1).

As the zwitterion contains both a carboxylate ion (-COO·) and an ammonium ion (-NH3 +) in the same molecule, an amino acid is regarded as having amphoteric character. In acid conditions it yields a cation and in basic conditions it produces an anion as shown in Figure 1.2 ff wool is acid or alkali hydrolysed, it yields eighteen a-amino acids as shown in Table 1.1 [10,11]. To elucidate the reactivity of wool, the character of each monomer unit should be studied A useful classification is according to the polarity of their respective side chain groups.

1.2.1.1. Nonpolar Side Chains

Glycine, alanine, praline, phenylalanine, valine, leucine, isoleucine, tryptophane and methionine are all hydrophobic side chains as they mainly consist of hydrocarbon groups. Of these, glycine, alanine and praline have small side chains and are weakly hydrophobic. The others,

4 Chapter 1 Introduction

phenylalanine, valine, leucine, isoleucine, tryptophane and methionine have larger side chains and are more strongly hydrophobic. These nonpolar groups form hydrophobic bonds with other nonpolar groups when present in polar environments.

1.2.1.2. Uncharged Polar Side Chains

All polar side chains are hydrophilic. The polar groups, acidic or basic, may exist in either an uncharged or charged state depending on the pH of the surroundings. For instance, the imidazole group of histidine is about 10% protonated and thus largely uncharged, while the hydroxyl group of tyrosine is weakly acidic and only about 0.1 % ionised at pH 7. Hence these amino acids and others such as serine, threonine and cystine are classed as being uncharged polar side chains.

1.2.1.3. Charged Polar Side Chains

Under neutral conditions the carboxylic acid groups of aspartic acid and glutamic acid are ionised and thus negatively charged. The amino groups of the side chains of lysine and arginine are protonated and thus positively charged, so that the wool fibre maintains electrical neutrality.

5 Chapter 1 Introduction

Reaction Reagents and Processes

Oxidation A1kaline or Neutral Chlorination

Reduction Finishing Process

Hyrolysis Finishing Process

Sulphation Sulphamic Acid

Acylation Acetic Anhydride

A1kylation Magnesium Bromide

Arylation Reactive Resists

Esterification Finishing Process

Table 1.2. Reactions of Wool relevant to Dye Resist Treatments Chapter 1 Introduction

Under acid conditions, aspartic acid and glutamic acid have an uncharged carboxyl group, whereas lysine, histidine and arginine are protonated so that the wool fibre carries a net positive charge. Conversely, under basic conditions, the carboxyl groups of aspartic acid and glutamic acid are ionised, while histidine, lysine and arginine are uncharged, and the wool fibre thus carries a net negative charge. However, in both cases, the charge is balanced by the counter ion of the acid or base, so the bulk fibre is not charged

In wool dyeing, which mainly occurs in acidic conditions, protonated groups within the wool fibre can attract acid dyes, which are anionic in character. Alternatively, under weakly acidic conditions, the nucleophilic character of the -NH2 groups in wool provide major sites for covalent bonding by reactive dyes.

1.2.2. Reactivity of Wool

It is generally recognised that wool fibres, by their nature and origin, are among the most heterogeneous materials to be subjected to physical and chemical studies [12]. Those reactions particularly relevant to this project are summarised in Table 1.2 and, for a more detailed coverage, the reader is referred to several recent books and review articles (4,12,13].

6 Chapter 1 Introduction

/ RSOSR RS02SR ~

RSSR \--- RSOH ----RSq H / RS03H

RSSOH RSSOH 3

where R : Wool-NH-CH-CO-Wool I CH 2 I

Figure 1.3. Oxidation of Cystine [41 Chapter 1 Introduction

1.2.2.1. Oxidation

The controlled oxidation of wool has important applications in bleaching, shrinkproofing and the isolation of soluble proteins from wool

The amino acids cystine, cysteine, methionine and tryptophan are all suscepttble to oxidation. Among these amino acids, cystine is the most abundant and hence the most significant modifications arising from the oxidation of wool result from the oxidation of cystine. Complete oxidation of cystine residues results in disruption of cross linking and the formation of cysteic acid as the final product. Intermediate oxidation products may, however, result under controlled conditions of oxidation as shown in Figure 1.3 [14].

Complete oxidation of cystine to cysteic acid by performic acid is used in the preparation of soluble proteins from woo~ for the purpose of quantitative determination of the cystine content of wool [15]. Mild oxidation involving hydrogen peroxide or chlorination treatments are utilised in wool bleaching and shrinkproofing, respectively.

Formation of cysteic acid during alkaline chlorination can confer dye resist effects as a result of electrostatic repulsion between cysteic acid · groups and the acid dye (see Section 1.3.8). Conversely, the loss of acidic amino acid residues during acid chlorination, or the formation of

7 Chapter 1 Introduction

W-S-S-W + ASH -- W-S-S-R + HS-W

W-S-S-R + ASH W-SH + R-S-S-R

where W : wool

Figure 1.4. Reduction of Wool with Thlols Chapter 1 Introduction

intermediate oxidation products of cystine during partial oxidation with permonosulphuric acid, can lead to dye assist affects.

1.2.2.2. Reduction

The treatment of wool with reducing agents has been used not only for the preparation of soluble protein derivatives but also for increasing the ease of setting wool

Reducing agents such as thiols and phosphines are fairly specific towards the disulphide ( cystine) residues of wool, resulting in conversion of each disulphide into two thiol (cysteine) residues. Reduction with thiols, for instance, proceeds via two sequential nucleophilic attacks at sulphur by the thiol anion, with mixed disulphides being formed as intermediates [13], as shown in Figure 1.4.

A similar reaction occurs during reduction with tnbutylphosphine [16], tetrakis (hydroxymethyl) phosphonium chloride (THPC) [17], sodium

sulphite [18], sodium or potassium borohydride [19] and the resulting thiols can then react with Bunte salts yielding mixed disulphide or new crosslinks [20].

1.2.2.3. Hydrolysis

8 Chapter 1 Introduction

w w I I HC-CH--R H C -CH-R I~ I =Q---H.. 0 HaN+ I ocr:J O=C 6- 16+ w w

N-Peptidyl O=Peptidyl

where W: Wool A: H (Serina) CH 3 (Threonine)

Figure 1.6. N --0 Peptidyl Shift Chapter 1 Introductlon

0 0-H 0-H II ~ I HP I W-C-NH-W w-q-NH-W W-C-NH-W - Hi" 0 I OH II W-C-OH HN-W + 2

Acid Hydrolysis

0 a 0 - II OH I Hi" II W-C-NH-W W-C-NH-W W-C-OH + H2N-W I OH

Alkaline Hydrolysis

Figure 1.5. Hydrolysis of Wool Chapter 1 Introduction

Hydrolysis of the peptide chain by acid or alkali involves cleavage of the

-NB-CO- bond resulting in the formation of -NH2 and -COOH end groups. Under acid conditions the attacking species is a protonated water molecule, while under alkaline conditions the strongly nucleophilic hydroxide ion attacks the amide carbon (Figure 1.5).

Acid hydrolysis is the most widely used method for converting wool fibres quantitatively into their individual amino acids. Hydrochloric acid is most commonly utilised for this purpose, although in 6N HCI at 110°C tryptophan is destroyed.

In acid hydrolysis, it was found that the rearrangement of peptide chains occurred with serine or threonine especially in the carbonising process [21 ]. This is called the N .. Q peptidyl shift as illustrated in Figure 1.6, which is rapidly reversed under alkaline conditions. However, in the presence of moisture, the O-peptidyls are easily hydrolysed by the acids because of labile ester bonds.

All proteins are vulnerable to degradation by alkali and prolonged exposure to alkalis causes hydrolysis of the peptide bonds leading to fragmentation and complete destruction. 0.1 N NaOH will rapidly dissolve wool at the boil. Solubility of the wool fibre in alkali has been used as a parameter for assessing damage during wet processing.

9 Chapter 1 Introduction

0 .. II CHQH 0 CH-OS-OH I II)' I 8 WNCH-COW + H-0-S-OH ---i--~WNCH-COW + H20 H II) H 0

CH 3 CH3 I .. - I ~ cHgH CH-0-S-OH 0 II I II)' I 0 WNCH-COW + H-0- -OH ----i..,_ WNCH-COW H II) H 0

where W=wool

Figure 1.8. Sulphation of Wool Chapter 1 Introduction

S-CHfH-W W-CHi9-C~W (Cysteinate Ion) w (Lanthionine crossllnk)

I H2N-(CHJ~H-W W-CH2NH-(C~)4-CH-W C=-CH (Lysine) (Lysinoalanlne) I 2 NH w + 3 W-CH2NH2 (Ammonia) (B-Amlnoalanine residue) (Dehydro- H2N-CHfH-W W-CH-C~NH-CHfH-W alanine (B-Aminoalanine) (B-Aminoalanine crosslink) residue)

H2N-(CH~-CH-W W-CH-C~NH-(CHJ:;CH-W (Omithine) (Omithinoalanlne)

COCH COCH I I CH COCOOH C=CH - Decomposition 3 C-CH 3 2 - (Pyruvic acid) I I + NH NH 2 NH 3

where W = wool residue

Figure 1. 7. Various Reactions of the Dehydroalanine residue Chapter 1 Introduction

ff wool is treated with alkali, the most common reaction is that of B­ elimination in the cystine, serine and threonine residues [22]. The mechanism of 8-elimination involves the abstraction of a proton from the 8-carbon atom producing a carbanion by the alkali and this carbanion forms a dehydroalanine residue. This residue crosslin.ks via the cysteinate ion by the rupture of disulphide bond or other amino group residues and forms new amino acid crosslinking residues, viz lanthionine, lysinoalanine, B-aminoalanine, ornithine, 8-aminoalanylalanine, ornithinoalanine [23]. The dehydroalanine residue also decomposes and pyruvic acid is produced [24]. These reactions are shown in Figure 1.7.

1.2.2.4. Sulphation

If wool is over-carbonised with sulphuric acid, it will partially resist the uptake of acid dyes [4]. This behaviour is presumably caused by the formation of 0-serine hydrogensulphate and 0-threonine hydrogen­ sulphate [25], as shown in Figure 1.8. As these residues have a strongly anionic character, they repel the entry of anionic dyes into the wool fibre. This type of dye-resist behaviour is discussed more extensively in Section 1.3.

10 Chapter 1 Introduction

. . 0 0 (1 I -,> ~; (1 r, RttC0NuH-W <- R-C-L <- R-C-L I+ I NuH-W Nu-W

0 II R-C- Nu-W + L

W=Wool L = Leaving Group Nu = Nucleophilic Group in Wool

Figure 1.9. Acylation of Wool Chapter 1 Introduction

1.2.2.s. Acylation

Acylation of wool may be carried out with acid anhydrides, acid chlorides, isocyanates, isothiocyanates and many other common acylating agents [26].

The reaction involves attack by a nucleophilic residue of wool at the electron deficient carbon atom of the acylating agent (Figure 1.9).

Asquith [27] emphasised two principles in formulating conditions for acylation:

(1) Nucleophiles are more effective in their unprotonated forms

such as RNB2, ArO·, RS·, hence higher reactivity of the

nucleophile is usually associated with a low pK

(2) Greater selectivity during acetylation of a nucleophile is often observed by using a highly reactive acylating agent at a low pH

or a weak acylating agent at a high pH.

The acylating agent typically undergoes nucleophilic substitution where the leaving group ( e.g. -OOCR) is replaced by a basic amino group of wool (:NH2-WOOL) [28].

The reaction consists of two steps:

11 Chapter 1 Introduction

(1) addition of the nucleophile to the carbonyl group, and, (2) e1imination of the leaving group.

The ease with which the leaving group ( :L) is lost depends upon its basicity: the weaker the base, the better the leaving group.

Acylated wool has a much lower basic group content than untreated wool, and thus weakly resists the uptake of acid dyes. The introduction of acidic groups, on the other hand, is known to provide stronger acid dye resist affects. The acetylation of wool has largely been carried out for the purpose of studying changes in mechanical properties which result from introducing additional hydrophobic interactions into the protein molecular structure.

1.2.2.6. Alkylation

A wide variety of alkylating agents have been shown to be capable of reacting with the functional side chains of many different amino acid residues, such as histidine, methionine, serine, threonine, tyrosine, lysine, and cysteine. Of these, cysteine is the most reactive. Iodoacetic acid is a commonly used alkylating agent for the purpose of blocking thiol groups in reduced wool, and bromoacetic acid can also be used for the purpose of blocking amino or hydroxyl groups of wool [29] ( see Section 1.3.6).

12 Chapter 1 Introduction

N02 O~-

Figure. 1 .11 · Reaction of FDNB Chapter 1 Introduction

.. .. W-NuH ----W- Nu-CH2COOH XCH 2COOH

where W = Wool .. .. -Nu = -NH, -S", v

X = Halogen

Figure 1.10. Alkylation of Wool Chapter 1 Introduction

In the preparation of soluble proteins from reduced wool, the thiol groups formed would air oxidise back to cystine if not blocked with an alk.ylating agent according to Figure 1.10 [30]. Vinyl sulphones may also be used for the same purpose and, depending on reaction conditions and pH, these alk.ylating agents will also react with lysine and histidine residues of wool.

1.2.2.7. Arylation

Benzene or naphthalene compounds containing electron withdrawing substituents such as nitro-groups, or aromatic heterocycles that contain strongly electronegative heteroatoms in the ring will undergo substitution reactions with nucleophilic residues in wool. Such reactive moieties have been widely used as protein determination reagents or as reactive groups in reactive dyes.

1.2.2.7.1. 1-Fluoro-2,4-dinitrobenzene (FDNB)

This reaction, as shown in Figure 1.11, was established by Sanger [31], and provides a useful analytical tool in protein chemistry.

FDNB reacts with various functional side chains as well as N-terminal

13 Chapter 1 Introduction

N020 - II o~ s-o o""- II 0 N02 -/ (TNBS) 0

2- + SO + H 3

Figure 1.12. Reaction of TNBS Chapter 1 Introduction

residues. Subsequent hydrolysis of the protein yields bright yellow dinitrophenyl (DNP) derivatives. These derivatives of amino acids, with the exception of that of cystine, are not decomposed during hydrolysis of the protein and hence may be isolated and identified This method has been used to assess which amino acid residues serve as binding sites for reactive dyes. As well, the method may be used to determine the extent of peptide bond hydrolysis during degradative treatments. Similar reactions can be found with 4-sulphonyloxy-2-nitrofluorobenzene (S~)

[32], 1,5-difluoro-2,4-dinitrobenzene (FFDNB) [33].

1.2.2. 7.2. Trinitro Benzene Sulphonic Acid (TNBS)

TNBS does not react with tyrosine or histidine side chains, hence it is suited to the determination of primary amino groups in peptide chains

[34]. The reaction mechanism is a typical nucleophilic substitution, in which the attacking nucleophilic replaces the sulphonate group of TNBS

(Figure 1.12). The presence of an electron withdrawing nitro-substituent on the benzene ring further activates the ring with respect to nucleophilic attack.

1.2.2. 7.3. Cyan uric Halides and Derivatives

14 Chapter 1 Introduction

I. Group 1 * Nucleophlllc groups attack the carboxyl groups. 6· I ? ('.. - I ? . W---C-O-H + OR' ---W---C-OR + OH 6~ I

II. Group 2 * Carboxyl anions act as nucleophilic groups.

? &-('6_ I W---C-O + R!_L---WCOOR'+ [ ~ I

where W = Wool R' = Alkyl group L = Leaving group

Figure 1. 13. Esterification of Wool Chapter 1 Introduction

S-triazine and diazines (pyrimidines, quinoxalines and phthalazines) are major reactive groups of reactive dyes. These reactions are discussed in more detail in Section 1.23.

1.2.2.8. :Esterification

Protein carboxylate groups may be esterified by alcohols, epoxides, active halogen containing compounds, or dimethylsulphate (Figure 1.13).

This reaction can be classified into two types. One type is the reaction in which protein carboxyl groups are attacked by nucleophilic groups on the carbonyl carbon of the carboxyl acid residue, while the other type is the reaction in which COO· groups of the protein attack reagents such as epoxides, active halogen containing compounds or dimethyl sulphates.

The resultant removal of carboxylate anions increases the uptake of acid dyes by wool, although this dye assist effect is not practical, as wool loses a substantial degree of strength on esterification.

1.2.3. Reactive Groups for Wool

Reactive dyes contain reactive functionalities that are capable of forming

15 Chapter 1 Introduction

6 + 6 + D---NH C --- CH 2 CI _II 1-· 6 0

Figure 1.15. Reactive Centre on Chloroacetamlde Dyes Chapter 1 Introduction

0-X-CH=CH + :NuH-W 2 - D = Chromophore X = Electron Withdrawing Group Nu = Nucleophilic Group in Wool W = Wool

Figure 1.14b. Nucleophilic Addition Chapter 1 Introduction

D-X ... L D-X-L + :NuH-W

Nu-H

I w

Transition State - D-X-Nu-W + H-L

D = Chromophore X = Activated Group L = Leaving Group W=Wool Nu = Nucleophilic Group in Wool

Figure 1.14a. Nucleophilic Substitution Chapter 1 Introduction

covalent bonds with the wool fibre. The result is that reactive dyes exhibit high fixation ratios after curing, as well as excellent wash fastness. Stamm [35] considered that the reaction systems in reactive dyeing could be divided into two categories:

(1) a substitution reaction in which a suitable leaving group on the dye molecule is replaced by a nucleophilic amino acid residue of wool (Figure 1.14a ), and, (2) nucleophilic addition to an unsaturated system of the dye molecule (Figure 1.14b ).

A characteristic difference between the two reactions is that the substitution mechanism proceeds irreversibly under normal dyeing conditions whereas the addition mechanism is reversible [35].

1.2.3.1. Reactive Dyes with a Chloroacetamide group

The reactive centre on the carbon atom is activated toward nucleophilic attack by the electronegative chlorine and carbonyl oxygen atoms (Figure 1.15). Reactive dyes with a chloroacetamide group may react with the lysine, histidine, cysteine, arginine, tyrosine and methionine residues in acid solution [36].

16 Chapter 1 Introduction

a /N~c5+ 6· D-NH-C .c-F II ~ I C6 N6- 6 c( "'.g/ I F 6

Figure 1.17. Reactive Centres (*) on 2,4-Dlfluoro-5-Chloropyrimldyl Dyes Chapter 1 Introduction

~N-D-SO 3 Na

Cl

Cl N

~( ~- H N-D-SO 3 Na NIN + HCI

Cl

where D = chromophore

Figure 1. 16b. Preparation of Chlorotriazinyl Dyes Chapter 1 Introduction

Figure 1.16a. Reactive Centres (*) on s-Triazine Dyes Chapter 1 Introduction

1.2.3.2. Reactive Dyes with a Chlorotriazine group

Mono- and dichlorotriazine groups, particularly the latter, are more reactive toward nucleophilic attack than pyrimidine groups. The reactive carbon centres are activated by adjacent electronegative chlorine and nitrogen atoms (Figure 1.16a ).

Chlorotriazine groups readily undergo nucleophilic substitution reactions with hydroxyl, amino and mercapto residues of wool. Dyes containing these groups are formed by the reaction of cyanuric chloride with a water soluble dye containing an amino group as shown in Figure 1.16b.

1.2.3.3. Reactive Dyes with a Chlorodi.Ouoropyrimidine group

The reaction mechanism for these dyes is similar to that for the chlorotriazine group, i.e. nucleophilic substitution. The feature of these dyes is their high fixation and high wet fastness properties since either or both carbons carrying fluorine atoms can form covalent bonds with the fibre (Figure 1.17).

The reactivity of pyrimidines is weaker than that of chlorotriazines. Hildebrand and Meier [37] observed that the carbon in the 4-position undergoes reaction first because of its higher degree of activation, but

17 Chapter 1 Introduction

CH3 I D-SQ-CH-CH-N-CH -CH -SONa 2 2 2 2 2 3

e,+ - D--S -- CH=CH2 ell • a 0

Figure 1.19. Reactive Centre (*) on Vinylsulphone Dyes Chapter 1 Introduction

H r o Br I "-II-If * + W-NH D-- N-C-C====CH2 2 o· o+

H O NH-W I 11 I Substitution D-- N-C-CH=CH2 o· o+

Addition H O Br NH-W I II I I D-- N-C-CH-CH2 o· o+

H O N-W I II /~ D-- N-C-CH-CH2

H O NH-W W-NH 2 I 11 I D--N-C-CH-CH2 - NH-W

Figure 1 .18. Reaction Mechanism of a-Bromoacrylamide Dyes Chapter 1 Introduction

the reactivity of the carbon in the 2-position is also sufficiently high for reaction with nucleophiles.

1.2.3.4. Reactive dyes with a m-Bromoacrylamido group

This reactive group can undergo nucleophilic substitution and nucleophilic addition. The reaction scheme is shown in Figure 1.18.

Model studies suggest that acrylamido dyes have reactivity with cysteine, lysine, histidine, and tyrosine residues but not with serine or threonine residues [38].

1.2.3.5. Reactive Dyes with a N-methyltaurine-ethylsulpbonyl group

These groups are unreactive at low pH but at pH 4.5-5.5 rapidly release the reactive vinyl sulphone form (Figure 1.19). The rate of formation of the reactive vinylsulphone dyes at the boil is very gradual [39], thus these dyes are claimed to be more level dyeing than other reactive dyes. The reaction mechanism for this group falls into the category of nucleophilic addition.

The double bond is activated by the presence of the sulphonyl group

18 Chapter 1 Introduction

Figure 1 .20. Bifunctional Dyes with Vinyl Sulphonyl and Cholorotriazine Groups * Reactive Centres (*) Chapter 1 Introduction

which forms a conjugate system with the carbon double bond. The electron deficient carbon atom thus becomes the centre for reaction. Von der Eltz [39] and Osterloh [40] studied the mechanism of this group in detail.

1.2.3.6. Reactive dyes with Bifunctional groups

There are two types of bifunctional reactive dyes that may be used on wool, one having two or more reactive systems of the same type and the other having two or more reactive systems of a different type.

ICI was the first to apply for a patent [41] relating to the introduction of two or more reactive systems of different types into one dye molecule. The patent characterised a series of dyestuffs containing two or more reactive groups of different types, and encompassed a wide range of reactive systems. Subsequently, many dyestuff manufacturers applied for patents producing dyes containing a combination of two different reactive systems. Among these, Sumifix: Supra dyes [42,43], containing a vinylsulphone group and a monochlorotriazine group; are commercially available (Figure 1.20).

1.2.4. Binding Sites of Wool

19 Chapter 1 Introduction

AMINOAOD FUNCTIONAL GROUP

Cysteine Sulphydryl

Lysine Amine

Histidine Imidazole

Arginine Guanidine

Tryptophan Indole

Serine Primary Alcohol

Threonine Secondary Alcohol

N-terminal Acid Amine

Tyrosine Phenol

Table 1.3. Reactive Functional Groups of Wool Chapter 1 Introduction

The reactive functional groups of wool are shown in Table 1.3. Shore [44,45] suggested in his model studies on protein systems that the order of decreasing reactivity of functional groups of wool is the sulphydryl groups of cysteine, the N-terminal amino group, the imidazole group of histidine, the amino group of lysine, the hydroxyl group of serine, the phenolic group of tyrosine, the guanidino group of arginine, and the hydroxyl group of threonine. He also indicated that the tryptophane group reacted only at high pH, and that the carboxyl groups of aspartic acid and glutamic acid did not participate in covalent reaction.

Corbett [46] observed that the reactivities of vinyl sulphone dyes with thiol, amino and hydroxyl groups were in the approximate ratio of 10,000:100:1.

Lewis [47] studied the reaction of chloroacetamido reactive dyes with model compounds and observed reaction with cysteine at pH > 2, histidine at pH >6, lysine at pH > 5, glycine and valine at pH > 7, cystine at pH > 7, tyrosine at pH > 7.5 and methionine at pH > 6.5.

It is pointed out that cysteine is the most reactive nucleophile, however, lysine, histidine and N-terminal amino groups are far more abundant, and therefore more important as binding sites in reactive wool dyeing. However, at the boil for pH > 3, disulphide is hydrolysed to cystine.

20 Chapter 1 Introduction

1.2.5. Dyeing of Wool

Most wool dyes contain sulphonate groups (-S03) which confer water solubility and anionic character. These sulphonate groups are attracted electrostatically by the side chains of arginine, lysine and histidine residues in wool, as these side chains normally exist in their cationic forms.

Although electrostatic interactions provide the main driving force responsible for the absorption of dyes by wool, they require reinforcement, especially by non-polar interactions between hydrophobic regions of the dye and wool fibre. The strength of these non-polar interactions largely determines the fastness of dyed wool to wet treatments, except in those cases where the dye undergoes an increase in molecular size or binds covalently to the fibre.

In general, four main types of interactions have been considered in wool dyeing [48] :

(1) Ionic links (Salt formation), (2) van der Waals' Forces and other dipole interactions, (3) Hydrophobic Interactions, and, ( 4) Covalent bonds.

21 Chapter 1 Introduction

1.2.5.1. Ionic links or Salt formation

Attraction of this bond plays a large part in the dyeing of wool fibres, viz. positively charged amino groups in the wool attract the anions of acid dyes, whilst negatively charged carboxyl groups attract basic dyes. The ionic links are easily broken.

1.2.5.2. van der Waals' Forces and other dipole interactions

If molecules approach very closely , they attract each other. The affinity of most wool dyes is largely due to these polar or non-polar van der Waals' forces. The strength of the attraction is proportional to the area of contact forces. Ion dipole forces are also important in dyeing, because they are responsible for the aqueous solubility of dyes.

1.2.5.3. Hydrophobic Interactions

The first description of these hydrophobic interactions is from Kautzmann's study of the alkyl side chains of proteins [49]. When two or more hydrocarbon residues of proteins approach together, some of the ordered water molecules surrounding them are released to the more disordered state as shown below.

22 Chapter 1 Introduction

~v6 VDVDV v HYDROCARBON I / v6v6VDV VDVDVDV RESIDUES before approach

v v vDv6v6vv vv vv HYDROCARBON DVD V RESIDUES II after approach v v v6v 6v6v6 v '(1:1 u

Figure 1.21. Hydrophobic bond [50] Chapter 1 Introduction

n [ Hydrocarbon (H2O) ] - ( Hydrocarbon ) + n H 2O

This process produces a sufficiently favourable entropy change to ensure that the equilibrium lies to the right (II after approach) Figure 1.21 [50].

Although the strength of a single hydrophobic bond is slight, the total number of hydrophobic interactions possible in a protein molecule is significant since about 30 percent of amino acids may have nonpolar side chains. This explains why the hydrophobic bond should be considered in the chemical reactions of wool.

1.2.5.4. Covalent Bonds

The bonds between reactive dyes and wool fibre molecules are of this type, which is much stronger than other forces and difficult to cleave.

1.2.5.5. The Role of Binding Forces in Dyeing and Printing

Maybeck and Galafassi [51] stated that ionic forces play a relatively small role in the binding of acid dyes to wool. They suggested that if the dyes are to have high affinity for wool, then hydrophobic character must be created in the dye molecule by placing the hydrophobic substituents

23 Chapter 1 Introduction

as far as possible from the polar groups in the dye molecule. Iyer et al. [52] have shown that hydrophobic interactions are important in the dye­ wool adsorption process and binding, especially at low temperatures.

Thus it should be born in mind that hydrophobic interactions play an important role in wool dyeing.

For example, in reactive dyeing, the covalent bonds will be the most important factor, whereas, in the application of Carbolan (ICI) dyes, the hydrophobic interactions will be important.

In resist processes, as normally employed in printing, by using dyes of low affinity but high reactivity, it should be possible, in theory, to achieve a high degree of dye resist [8].

1.3. Resist Processes

In order to research dye resist agents, it is first necessary to investigate the history of dye resist processes. An effective dye resist process has long been sought [53,54,55] as an alternative to the conventional discharge processes used in wool dyeing and printing. Furthermore, dye resist agents have also shown potential as reserving agents during the union dyeing of wool/nylon or wool/cotton blends [56]. Although many

24 Chapter 1 Introduction

researchers have sought to establish effective dye resist processes, no particular technique has gained widespread practical use.

Resist processes for wool may be classified into four categories:

Method Resist Type

Physical Method Coating the surface of the wool

Blocking the pores of the wool

Eliminating the basic side chains in wool Chemical Method Introducing additional acidic groups

Table 1.4. Dye Resist Methods

1.3.1. Coating Method

This method is the oldest resist process, dating back as far as ancient Egypt, 1500 BC [2]. The resist effect is obtained by forming a pattern with some substance which provides a physical barrier between the fabric and the colorant, in order to prevent the colorant from penetrating into the fabric. The types of substances which are used in this method are high molecular weight waxes, fats, resins, thickeners and pigments. This

25 Chapter 1 Introduction

method is, however, only rarely used commercially these days, with the exception of the "Batik" style which is still popular on cotton. Today, Indonesian Batiks are still produced where the pattern is applied to the fabric using molten wax. This process requires much time and labour.

1.3.2. Tannic Acid

The first patent [57] for this dye resist process on wool dates back to 1900 in Germany. In this process, wool is first boiled in a solution of tannic acid. Fixation of the absorbed tannic acid is accomplished in a second step by treatment with metal salt solutions based on a mixture of antimony and tin salts [58,59]. Various modifications of this process have been reported [60,61], for which the most recent involves the replacement of stannic and antimony salts with cheaper and less-toxic aluminium salts [62,63,64].

The resist effect is achieved by introducing into the fibre insoluble compounds that provide a physical barrier which obstructs the penetration of dye molecules into the fibre. In addition, tannic acid compounds are themselves acidic (anionic) and thus electrostatically repel the adsorption of acid dye molecules. In fact, the tannic acid process formed the basic concept for the development of subsequent dye resist processes for wool that involve the internal deposition of

26 Chapter 1 Introduction

substances into the fibre, that serve to restrict the uptake of dyes by the fibre (see Sections 1.3.5 & 1.3. 7).

This treatment gives a moderate resist effect but the shade achieved is quite dull and discoloured [65]. Although this process has been improved and simplified, it has not been used widely in the textile industry.

1.3.3. Acetylation

This dye resist process [66] has long been suggested as a dye resist method for wool. The substrate is treated with glacial acetic acid and acetic anhydride in the presence of mineral acids or acid salts. The mechanism of this process is explained as follows:

As mentioned earlier (Section 1.2.2.5. ), this reaction belongs in the class of nucleophilic acyl substitution. A nucleophilic residue from wool ( :NH2) attacks the carbonyl carbon of the anhydride, with the acetate anion

(CH3COO·) forming the leaving group. As the activated carbon and leaving group both lie in the same plane, the molecule is especially suited to undergo nucleophilic substitution.

27 Chapter 1 Introduction

-NH HO-CH-SO Na W-NH-C-- + I 3 ---NH2 OCH

~N-CH-SONa R-NH-C I ~N-CH

Figure 1.22. Condensation Reaction between Glyoxal bis sodium bisulphite and arginine Chapter 1 Introduction

The dye resist effect produced is claimed to be superior to that obtained from earlier methods [67], however, the main drawback of this method is that special equipment is required and it is thus unsuitable for commercial utilisation. Asquith et al. [68] subsequently developed an improved dye resist process in the presence of sulphuric acid ( see Section 1.3.10).

1.3.4. Glyoxal Bis Sodium Bisulphite

This process, developed by Elliot and Speakman [69], is considered to involve a condensation reaction between glyoxal-bis-sodium bisulphite and basic amino acid residues, such as arginine, in wool. The reaction may be represented as shown in Fig. 1.22, and results in the removal of basic side chains as well as the introduction of acidic sulphonate groups into wool, thus conferring a good resist effect. The drawback to this method is that reaction with wool is not complete and the sulphonic acid groups are not retained by all the imidazole rings in the treated wool [70,71].

1.3.5. Naphtholsulphonic Acid Salts with Formaldehyde

Elliot [71] further developed the concept of a resist effect obtained by

28 Chapter 1 Introduction

the introduction of acidic groups into the wool fibre. In this process the condensation of naphtholsulphonic acid salts and formaldehyde within the wool fibre gives rise to wool that resists the uptake of acid dyes. Although the resist effect has been described as quite good, the substrate is somewhat discoloured by this process [72].

1.3.6. Magnesium Bromoacetate

Da Silva et al. [29] have studied the prolonged treatment of wool with bromoacetic acid in the presence of magnesium oxide. It was claimed that both lysine and histidine residues in the wool fibre were modified as follows:

W - NH2 + CH2BrCOO· ----> W - NH - CH2COO· + HBr W - NH2 + 2CH2BrCOO· ----> W - N - (CH2COO·)z + 2HBr

W - CH2 - CJ15 - OH + CH2BrCOO· ----> W - CH2 - CJls - 0 - CH2COO· + HBr

The reaction decreases the basic group content of the wool, by replacing it with carboxyl groups, and thus produces moderate resist effects. Although this process has the advantage of conferring dye resistance without significant damage to wool, the cost of bromoacetic acid is too high for commercial implementation [73].

29 Chapter 1 Introduction

1.3.7. Synthetic Polymers

Acrylic acid or methacrylic acid is polymerised within the fibre via free radical initiation with ammonium persulphate as a catalyst [70,74,75]. The polymeric deposits formed within the fibre have acidic properties and thus repel anionic dyestuffs. The fact that the dyeing properties of wool are altered by the internal deposition of the polymers was confirmed by Needles et al. [76], by studying the fixation of various acidic, basic and reactive dyestuffs to polymer grafted wool. Depending on the grafted monomer system and dyestuff used, various levels of assist and resist effects were obtained In some cases the polymer deposit was considered to open up the structure of wool toward dye absorption. In an earlier review [77], polymer deposition, however, was said to result in deleterious effects on the handle and colour of the wool .

1.3.8. Alkaline or Neutral Chlorination

The oxidative chlorination of wool under acid conditions has been studied extensively [78, 79,80] and forms the basis of important shrinkproofing methods. Acid chlorination has also been used to prepare fabrics for printing because it accelerates penetration of the dye into the fibre. This dye assist effect is probably due to modification of the

30 Chapter 1 Introduction

epicuticle [81]. The chlorination of wool under a1ka1ine or neutral conditions, however, shows the opposite effect, that is, a dye resist effect [82,83]. In fact the cross dyeing of fabric [84] is based on a technique where multicolour effects are obtained by dyeing fabrics constructed of fibres or yams that have different dyeing characteristics, such as those treated by acid chlorination and those treated by alkaline chlorination. Acid chlorinated wool that is dyed shows poor wash fastness, whereas the wash fastness of dyed wool pre-treated by alkaline chlorination is as good as, and in some cases, superior to the washfastness of the untreated wool.

The mechanism of alkaline chlorination has not yet been clearly elucidated A possible explanation for this behaviour is that the reduced absorption of acid dyes by alkaline chlorinated wool is connected with an increase in the number of acidic groups in the wool produced by oxidation of disulphide bonds. However, this explanation is not entirely satisfactory, since it has been shown that silk (which contains virtually no cystine) treated by alkaline chlorination is also dyed less than untreated silk [85].

1.3.9. Oxidation by Periodic acid

The mechanism of dye resist by this method is similar to that of the alkaline chlorination method. Whewell et al. [86] investigated the

31 Chapter 1 Introduction

effect of pretreatment with various oxidising agents on the dyeing behaviour of wool. Among peroxy-monosulphuric acid, periodic acid, iodic acid and iodine as oxidising agents, only periodic acid showed a dye resist effect, while all others conferred dye assist effects. Whewell et al. explained this by assuming that during periodic acid oxidation a number of fully ionised negatively-charged groups, such as S03, were introduced into the fibre so that repulsive effects towards dye anions were conferred. This proposal is consistent with the observation that periodate cleaves considerably more disulphide bonds than does peroxy­ monosulphuric acid under similar conditions [87]. The subsequent oxidation of the cleaved disulphides to cysteic acid residues explains the fact that periodate-treated wool shows a reduction in the uptake of anionic dyes.

1.3.10. Sulphation with concentrated sulphuric acid

This process has been studied as a feasible resist method ever since a dye resist effect was observed with over-carbonised wool [88]. Asquith et al. [64] re-evaluated the acetylation process and improved the process without the use of acetic anhydride, using sulphuric acid, thereby making it unnecessary to use special equipment. Although this process was claimed to give a considerable dye resist effect, the anhydrous conditions necessary rendered the method unsuitable to commercial adaptation.

32 Chapter 1 Introduction

Maclaren et al. [89,90] have described another sulphation process which involves the treatment of wool with a mixture of 70 % v/v cone. sulphuric acid and 30 % v/v ethanol, for 5 min at room temperature. Although it is claimed that an excellent dye resist effect is obtained, including flame retardancy, this process has also not been used in practice due to the anhydrous conditions required

1.3.11. Synthetic tannic agents

Syntans (Synthetic tanning agents) [91] were first introduced in the literature in 1913. At first, these products were made only as substitutes for natural tanning agents in the leather industry. As the use of the tannic acid process diversified these syntans were also utilised in various other ways, such as to improve the wetfastness properties of dyed nylon fibres, or to retard the uptake of dye by nylon fibres during the union dyeing of wool and nylon [92,93,94,95].

The chemical structure of these products is not generally known, although they are considered to be high molecular weight condensates of sulphonated naphthyl amine phenols or naphthols with formaldehyde [95].

33 Chapter 1 Introduction

Shore [94] compared the effectiveness of Taninol WR (a syntan) with a natural tannic acid treatment on nylon. He concluded that the syntan penetrates into nylon much less completely than the tannic acid, and that the syntan is more effective in preventing the uptake of dye by undyed fibres than in minimising the loss of dye from dyed fibres. More recently, other researchers have studied the uptake of dyes with other syntan systems [95,96].

It is postulated that the deposition of the syntan in the outer regions of the fibre acts as an initial barrier to dye diffusion [96]. The drawback of these syntan systems is that while they initially exlubit a retarding effect, they gradually lose this retarding efficiency as dyeing proceeds, by slowly diffusing into the fibre. Thus the restraining effect, with respect to dye equilibrium uptake is only marginal [96]. Recently these materials have begun to be used as stain blocking agents for nylon [97,98].

1.3.12. Irradiation with UV or y Rays

It is claimed that if wool is irradiated with low levels of UV or y rays, a dye resist effect is produced [99,100]. This is considered to be possibly due to the photochemical modification of the epicuticle.

1.3.13. Sulphamic acid

34 Chapter 1 Introduction

In 1955, Helfenberger and Hagenbuch from Sandoz [101] patented a dye resist process using sulphamic acid At that time this process did not attract much attention. Since then many researchers [102,103,104] have studied the dye resist effects achieved when sulphamic acid is applied to wool.

Elliot et al. [102] concluded that reaction of wool with sulphamic acid occurred at the amino groups, cystine groups and hydroxyl groups of wool. Lewin et al. [103] studied the reaction between sulphamic acid and wool for the purpose of achieving flame retardancy. Recently, Bell et al. [104] studied the dye resist effect of sulphamic acid treated wool and it was found that the resist achieved by sulphamic acid on wool to acid dyes and reactive dyes was superior to propriety products. Cameron and Pailthorpe [105] reinvestigated the reaction of wool with sulphamic acid These researchers claimed the reaction takes place predominantly with the alcoholic amino acid residues, while some reaction also occurs at the primary amino groups. The cystine linkage was found not to directly participate in the reaction with sulphamic acid. They found that optimum reaction took ,place at 150-160"C for 3-5 minutes in the presence of urea.

1.3.14. Reactive resist

35 Chapter 1 Introduction

No. Year Method Resist Type

8 1948 Alkaline Ch Chlorination

9 1971 Periodic Acid Ch

10 1937 Sulphation Ch 1955 Method

11 1971 Synthetic Tannic Ch Agents

12 1961 Irradiation Ch

13 1970 Reactive Resist Ch

Ph : Physical Type Ch : Chemical Type

Cont'd Table 1.5. Dye Resist Methods for Wool Chapter 1 Introduction

No. Year Method Resist Type

1 BC1500 Coating Method Ph

2 1900 Tannic Acid Ph, Ch

3 1922 Acetylation Ch

4 1943 Glyoxal Bis Sodium Ch Bisulphite

5 1944 Naphtolsulphonate Ph,Ch and Formaldehyde

6 1955 Magnesium Ch Bromoactate

7 1946 Synthetic Polymers Ph,Ch

Ph : Physical Type Ch : Chemical Type

Table 1.5. Dye Resist Methods for Wool (Cont'd) Chapter 1 Introduction

Since Rattee and Stephen [106] discovered reactive dyestuffs, a large number of reactive groups have been introduced At the same time, a number of companies have begun to attempt to use these groups in colourless dye resist agents. Several patents [107,108,109] have subsequently been published for reactive dye resist processes.

Sandoz [110] also invented a reactive resist agent for polyamide fibres for the purpose of achieving multicolour effects. Sandospace-R is commercially known as an important dye resist agent [111 ]. Recently Bell et al. [8] have investigated a variety of triazine reactive compounds with the aim of developing a suitable reactive resist for wool.

All the above dye resist methods can be summarised as in Table 1.5. According to this table, it can be noted that the direction of research has changed from physical methods to chemical methods, especially after the development of reactive dyeing, utilising a variety of reactive groups.

1.4. Methods for the assessment of the dye resist effect

The available methods for assessing dye resist effects have not been standardised officially. First of all it should be noted that, in order to study dye resist effects, it is necessary to distinguish dye retard effects from dye restrain effects. These two terms are often used

36 Chapter 1 Introduction

interchangeably. Here, however, it is important to differentiate a dye retard effect from a dye resist effect The dye retard effect can be defined as one in which the treated wool takes up dye at a slower rate than untreated wool, whereas the dye restrain effect can be defined as one in which treated wool absorbs less dye than untreated wool at equilibrium exhaustion.

1.4.1. Resist Number (RN)

This method was used by Elliot [71 ]. The effectiveness of a resist achieved is indicated by a "resist number", or RN, which is the visual assessment between the standard dyed sample and corresponding dye resist treated one. He prepared a set of standard patterns by dyeing untreated fabric to various stages of exhaustion. After dye resist treatment, the colour of a treated sample was compared visually with that of one of the prepared standard samples, and the RN was given according to the percentage value of the standard sample. The more effective the treatment the smaller will be RN. Although this expresses the dye restrain effect, it would be very subjective.

1.4.2. Percentage Resist Value

37 Chapter 1 Introduction

The percentage resist value was quantified by Bell et al. [8]. The formula is as follows:

Resist Percentage - (K/S)u-(K/S)t x 100 (K/S)u

in which K = Absorption Coefficient S - Scattering Coefficient (K/S)u - Ratio of K to S of Untreated Wool (K/S)1 = Ratio of K to S of Treated Wool

The value of K/S can be calculated by the following relationship (known as the Kubeika-Munk equation) for the reflectance R of a sample with the constants K and S at one wave length under certain circumstances:

K (1-R )2 -----1

where R1 = the reflectance of the fabric at the wave length of maximum absorption

K/S is directly proportional to the dye concentration and hence the amount of dye in the fabric. The reflectance values can be obtained using a suitable spectrophotometer.

38 Chapter 1 Introduction

1.4.3. Dye Absorption method

If the exhaustion curve is plotted against the square root of time, the dye resist effect can be assessed in comparison with untreated materials. Only this method can account for both the dye retarding effect and the dye restraining effect at the same time. The retarding effect is determined by the rate at which dye is adsorbed by the substrate, while the restraining effect is determined by the equilibrium dye uptake of the substrate [112].

1.5. Low Temperature Dyeing of Wool

As the aim of this project is to develop a low temperature curable dye resist agent for wool, it is essential to survey the existing low temperature dyeing processes. Wool dyeing is normally carried out in boiling dyebaths to dissociate dye aggregates and promote the diffusion of dye into the fibre. However, if wool dyeing is carried out at temperatures below the boiling point, there are many advantages such as reducing energy costs, preventing yellowing of the fibre, and reducing loss in fibre strength. A number of low temperature dyeing processes have been proposed

1.5.1. Organic Solvent Method

39 Chapter 1 Introduction

The addition of organic solvents, such as amyl or benzyl alcohol, to aqueous dye baths causes a great increase in the rate of dyeing and allows dyeing to be carried out below 60°C [113,114]. The treatment with solvents is expected to remove hydrophobic materials from the fibre and hence speed up the rate of dyeing [113].

1.5.2. Formic Acid Method

The effectiveness of formic acid in promoting dye uptake is presumably due to three factors. Firstly, wool is more swollen in formic acid than in water and formic acid decreases the barrier to diffusion of dye through the fibre. Secondly, the dielectric constant of formic acid is high so that ionic interactions between dye and wool are promoted. Thirdly, the sulphonate group of dye is ionised, while the carboxyl groups of the wool fibre are unionised so that the wool shows maximum acid binding capacity because of attractive Coulombic forces between the dye and the wool [115]. This method is also not widely adopted commercially because of the hazardous nature of, and the need to recover, the acid after dyeing.

1.5.3. Amine Pretreatment Method

40 Chapter 1 Introduction

If wool is pretreated with an alkylamine, the modified wool exlubits a remarkable dye assist effect [116,117]. This effect is so great that the modified wool can be dyed at low temperature, nearly at room temperature. The suggested explanation of this effect is that dye uptake is increased by the introduction of additional basic groups. This explanation is disputed by other authors, however, who suggest that the effect is due more to the promotion of swelling of the fibre [118]. The mechanism of this dyeing method is still being debated.

1.5.4. Surfactant or Auxiliary Addition Method

When nonionic surfactants such as Llssapol TN450 (a condensate product of nonylphenol and ethylene oxide, ICI) or textile auxiliaries like Albegal B (an amphoteric levelling agent, Ciba Geigy) are added, low temperature dyeing is possible, but not below so·c [119,120]. The mechanism is not yet clearly explained, but the dye exhaustion appears to be determined by surface adsorption [120].

1.S.S. Cold Pad Batch Process

This method was developed by the IWS and Ciba Geigy [121,122,123]. Lewis and Seltzer [121] descnbed a method for

41 Chapter 1 Introduction

the dyeing of wool fabric with reactive dyes using a pad-batch process with concentrated solutions of urea at room temperature. It was observed that almost complete fixation could be obtained with dichloro-s­ triazine dyes, applied from solutions containing a high concentration of urea under mildly acidic conditions, after batching for up to 24 hrs at room temperature. The rate of fixation increased with temperature. Addition of 1 % sodium bisulphite to the dye liquor also increased the fixation rate [124]. Urea enhances the rate of dyeing by dissociating dye aggregates and by increasing the rate of diffusion within the fibre.

The advantage of this method is that bright colours of high wet fastness and good levelness are achieved. The use of low temperature decreases fibre yellowing and degradation. However the drawback is that the process requires a high concentration of urea.

1.6. The Aim of This Project

As mentioned earlier, at present as there is no dye-resist process for wool that is entirely satisfactory. Thus it is necessary to establish more effective dye resist methods and to systematically investigate the resist effects achieved. The aim of this project is therefore to develop new and improved methods for the preparation, application and curing of dye resist agents on wool in order to achieve a dye resist effect at low

42 Chapter 1 Introduction

temperature, and to elucidate the mechanisms of the dye resist effect.

1.6.1. The Requirements of a Low Temperature Curable Reactive Resist

In order to provide a commercially viable method, low temperature curable reactive resist agents should satisfy the following conditions: 1) Reactive Resists should not deleteriously affect fibre handle or appearance. 2) Reactive Resists should not cause fibre yellowing. 3) Reactive Resists should be manufactured economically. 4) Reactive Resists should be soluble in water but withstand hydrolysis during processing. 5) Reactive Resists should be curable at low temperature. 6) Reactive Resists should have high fixation, and good wash fastness during subsequent processing. 7) Reactive Resists should have low toxicity and carcinogenicity.

1.6.2. Approach of the Present Work

In order to develop a viable dye resist agent for wool, the dyeing characteristics of sulphamic acid, the currently most successful resist agent, were first studied Following this, dye resist compounds

43 Chapter 1 Introduction

containing the s-triazine reactive group were investigated, and the dye resist effect was assessed quantitatively.

The reason that the s-triazine reactive group was chosen in preference to all others was that the reaction between dyes containing this group and protein can occur at low temperature in a pad-batch method [121 ]. It is well known that the chlorotriazine dyes react with wool at room temperature. Although these dyestuffs are rarely used in normal wool dyeing because of their tendency to hydrolyse, they were employed extensively in the cold pad batch dyeing of wool.

In conclusion, the following scheme seems to suggest itself. If products can be synthesised which have anionic groups and can be cured at low temperature to react with and block the cationic side chains of wool, then these products should exhibit a low temperature curable dye resist effect. Considering these requirements, a model structure for reactive dye resists can be proposed as follows:

X ----NH----Ar----[ (S03)" 1D where X represents a suitable wool reactive group, NH is a bridging group, Ar is an aryl group, and S03 functions both as a water solubilising and an anionic dye repelling group.

44 CHAPTER 2. DYE RESIST EFFECTS ON SULPHAMIC ACID TREATED WOOL

2.1. Introduction

As previously mentioned in Section 1.3.13, the sulphamic acid resist process is currently the most successful dye resist process for wool; however, the curing temperature is too high and may damage the wool. If the curing temperature could be reduced from 150° C to the drying temperature normally employed for wool (100-120° C) or, if possible, to room temperature, then this process could be widely employed in the wool textile industry and this project would achieve its aim.

A study of the dye resist effects on sulphamic acid treated wool, particularly in terms of curing temperature, is therefore considered to be an essential part of the present work.

The question arises as to why sulphamic acid plays a role only at high temperature (140 - 150°C). Several hypotheses can be formulated to answer this question.

Firstly, if sulphamic acid is only able to react with wool at high temperature, sulphamic acid treated wool cured at temperatures below 140° C would not show a dye resist effect.

45 Chapter 2 Dye Resist Effects

Secondly, although sulphamic acid can react at high temperature, if the extent of reaction with the fibre was not almost complete, desorption of free sulphamic acid might occur during the subsequent dyeing process.

If the mechanisms associated with these reactions could be elucidated, then a method could be developed to enable sulphamic acid to react with wool at low temperature and hence have sufficient substantivity to withstand subsequent washing or dyeing processes.

According to the results of Cameron et al. [125], the optimised conditions for maximum uptake of sulphamic acid were to treat the wool with a solution containing 20 % sulphamic acid, 20 % urea and 0.1 % Lissapol TN450 for 30 min at 40°C, followed by padding, drying at 80°C and curing at 150° -160° C for 4-5 minutes.

Thus wool fabric was treated with sulphamic acid and the dye resist effects were investigated using different curing conditions and dyestuffs. The results of these studies were analysed and have led to a possible explanation for the nature of the reaction between sulphamic acid and wool.

2.2. Dye Resist Effects on Sulphamic Acid Treated Wool

2.2.1. Materials and Methods

46 Chapter2 Dye Resist Effects

0 ~COCH3 N=/~ V Nao i ------S°:3Na 3

OH NHCOCH 3

CH (C~) N=~_---.__--_--- 3 o------. 1 VI 11 -- /~ H~S / -- --- S°:3Na

Br I HC=CCOHN 2

Figure 2.1. (cont'd) Dye Structures Chapter 2 Dye Resist Effects

Nao3s-g-·.. ::•· N=:o-g- .. :.. ·

I ; I

··-··--·-·-·" -. ______

II

Ill

SO Na 3

IV

Figure 2.1. Dye Structures (cont'd) Chapter 2 Dye Resist Effects

Commercial Colour Index Colour Index Chemical Number of Name Name Number Structure* -SO3 Groups

Acid Red 88 Cl Acid Red Cl 15620 I 1 (Aldrich) 88

Crystal Cl Acid Red Cl 16250 II 2 Scarlet 44 (Aldrich)

Amaranth Cl Acid Red Cl 16185 m 3 (Aldrich) 27

Acilan Pone Cl Acid Red Cl 16290 IV 4 6R (F.By) 41

Azo Cl Acid Red Cl 18050 V 2 Rhodine G 1

Carbolan Cl Acid Red Cl 118073 VI 2 Crimson BS 138

Lanasol ------VII 2 Type

Irgalan Type ------VIII 0

* See Figure 2.1

Table 2.1. Dyestuffs used Chapter 2 Dye Resist Effects

2.2.1.1. Fabric

The wool fabric employed was a scoured and decatised 2/2 twill, weight

270 g/m2, supplied by John Vicars Fabrics, Sydney.

2.2.1.2. Dyes

2.2.1.2.1. Dye Structures

A series of acid dyes were selected which have different numbers of sulphonate groups but the same chromophore. In addition, one Irgalan type metal complex dye and one I..anasol type reactive dye were selected (The structures of the latter two dyes were disclosed on the condition that the commercial names were not specified in this thesis.) The Colour Index names and the Cl Numbers for these dyes are summarised in Table 2.1. The chemical structures of the dyes are given in Figure 2.1.

2.2.1.2.2. Purification of Dyes [126]

The commercial dye (10 g) was dissolved in boiling DMF ( 400 ml), filtered and the resultant solution free of inorganic material was precipitated by the addition of acetone (100 ml) or trichloroethylene (100 ml). The precipitated dye was removed by filtration, washed with acetone or trichloroethylene and dried below 50° C. The procedure was

47 Chapter 2 Dye Resist Effects repeated until the absorbance of a solution of given concentration was optimised

2.2.2. Application of Sulphamic Acid to Wool

2.2.2.1. Application of Sulphamic Acid

Wool samples were treated with the sulphamic acid mixture by a pad­ dry-bake procedure as follows:

Sulphamic acid 20% wt/wt Urea 20% wt/wt Lissapol TN 450 (ICI) 0.1 % (nonylphenylnonaoxyethylene glycol)

The wool samples were then padded through a vertical pad mangle (Konrad Peter AG. Llestal M2F-50) to achieve approximately 70 % wet pick-up. The samples were then dried at 85°C for 15 minutes and baked for 5 min at 100°C or 125°C or 150°C in an oven (Hanau Co. Heraeus UT6120). The samples were then rinsed thoroughly in about 50° C warm running water.

2.2.2.2. Dyeing Methods

48 Chapter 2 Dye Resist Effects

All dyeings were carried out in a thermostatically controlled dyebath ( John Jeffreys Dye Master Engineering Co.). The dyeing methods employed were as given in the Colour Index [127]: (Percentages are w/w) Dyebath: Acid Levelling Dye 0.5% Dye 1.0% Formic acid (pH 3.0) 10.0% Sodium sulphate

Acid Milling Dye 0.5% Dye

1.0% CH3COOH (pH 5.0) 10.0% Sodium sulphate

Reactive Dye 0.5% Dye

1.0% CH3COOH (pH 5.0) 10.0% Sodium sulphate

Premetallised Dye 0.5% Dye

1.0% CH3COOH (pH 5.0) 10.0% Sodium sulphate

Liquor Ratio: 100:1

49 Chapter 2 Dye Resist Effects

Temp (°C) 120

100

80

Rinsing 60

40

20

0 0 20 40 60 80 100 120 140 180 l Time (mln) 1 Dye Auxiliaries Figure 2.2. Dyeing Cycles Chapter 2 Dye Resist Effects

Method: The wool samples were thoroughly wet out in a 0.1 % Lissapol TN 450 solution and hydroextracted before dyeing. The samples were entered at 40° C and run for 5 min. The temperature was then raised to 100° C over 60 min and held at 100° C for 80 min. Dyed samples were washed off at 50° C in running water. During the course of dyeing, the losses from the dye bath due to evaporation and sampling were made up with distilled water. The dyeing cycle is shown in Figure 2.2.

2.2.2.3. Dye Exhaustion Curve

Dye exhaustion was determined using a liquor ratio of 100:1. In all cases 0.5% dye was used as this concentration is convenient for the measurement of optical density. During the course of dyeing, a 3 ml aliquot was withdrawn from the dyebath and placed into one of a series of marked test-tubes to measure the optical density. Each of these solutions was transferred to the spectrophotometer sample-cell (path­ length: 1.0 cm). The spectrum in the visible region over the range 400- 700 nm was measured using a Cary 210 Spectrophotometer (Varian Co.). The wave length of maximum absorption ( lmax) and the optical density at this wavelength were obtained. The percentage exhaustion was calculated by the following formula:

50 Chapter 2 Dye Resist Effects

E Ex (%) - (1- Et) X 100 0

where Bi : optical density at time t Bo : optical density at time 0 Ex : Exhaustion % of sample

The dyed samples were retained for the measurement for the dye resist effect and colour difference. (Note: Beer's law was obeyed in this work.)

2.2.2.4. Determination of pH of the Aqueous Extract of Sulphamic Acid treated Wool

The pH of the aqueous extract of sulphamic acid treated wool was determined by Australian Standard Method 2001.3.1 - 1977 (Deter­ mination of pH of Aqueous Extract) [128] using an Orion pH meter ( Orion Research Inc. 520A ).

Three extraction procedures were examined to compare the pH of the extract. 1) Test A - Cold Water Extract: A sample was shaken in deionised water for 1 hour and the pH of the aqueous extract measured.

51 Chapter 2 Dye Resist Effects

2) Test B - Boiling Water Extract : A sample was boiled in deionised water for 1 hour and the pH of the cold aqueous extract measured 3) Test C - Boiling Water under Reflux Extract : A sample was boiled in deionised water for 1 hour under refluxing conditions and the pH of the cold aqueous extract measured

For Test A, 2.0 g sulphamic acid treated wool sample, as described in Section 2.2.2.1, was placed in a conical flask of 250 ml and 100 ml of distilled water was added. The temperature was recorded. Then the flask was shaken vigorously for 30 sec to thoroughly wet the sample after which time it was placed in a mechanical shaker and shaken for 1 hour.

In the case of test B, the flask was placed on a hot plate and was brought to the boil quickly and boiled gently for 1 hour. During boiling, boiling water was added to maintain the water level in the sample flask. After boiling, the extract was cooled and the pH was measured.

In the case of test C, the flask was placed on a hot plate and fitted a reflux condenser. It was brought to the boil quickly and gently boiled for 1 hour. After boiling, the extract was cooled and the pH was measured

In order to investigate pH variations during the dyeing procedure, the

52 Chapter 2 Dye Resist Effects pH was also measured in the dye bath.

2.2.2.S. Dye Resist Evaluation

The extent of dye resist achieved was quantified by calculating the K/S values of the dyed and untreated wools using the formula below as described in Section 1.4.2 The reflectance values were obtained using a Gardner Neotec Spectrogard Colour Computer System (Pacific Scientific Company).

Resist Percentage - (K/S)ut-(K/S)tr x 100 (K/S)ut

in which ut : untreated wool tr : treated wool K : Absorption Coefficient S : Scattering Coefficient

2.2.3. Results and Discussion

2.2.3.1. Optimum Curing Temperature

A preliminary study was carried out to confirm the optimum curing

53 Chapter 2 Dye Resist Effects

pH 6

5

A-- _/\ ~----&-----b-. []...... ---~----8----8 ······[]_ 4

·o...... H···············B················EJ 3 G------G -- ---G ------G------o------E)------0

2 0 2 4 6 8 10 12 time vmin untreated 100 125 150 ---4- --B-- ····H··· - 8-

Figure 2.5. pH Variation ( Lanaaol Type ) Chapter 2 Dye Resist Effects

pH 8

5

4

3

2

100 125 150 temp (deg C) ~ testA LJ testB ~ testC

Figure 2.4. pH variation vs curing temperature Chapter 2 Dye Resist Effects

Reaiat, % 100.------,.,--,

80

80

40

20

o~-====::!:it::::::==:::::;::=:=:5:'..__...... ______L__ ..___ _ _J 0 40 80 120 180 Curing temperature, •c

Figure 2.3. Resist effect for Lanasol Type dye versus curing temperature for sulphamic acid treated wool (20% sulphamic acid, 5 min) Chapter 2 Dye Resist Effects temperature for sulphamic acid treated wool which achieves a maximum dye resist effect.

It can be seen from Figure 2.3 that an effective resist can be achieved only above a curing temperature of 140° C in the sulphamic acid dye resist process. This result is consistent with that obtained by Cameron et al. [125], and correlates with the pyrolysis characteristics of sulphamic acid. This phenomenon will be discussed in detail later.

2.2.3.2. The pH Variation of Sulphamic Acid treated Wool at Different

Curing Temperatures

Figure 2.4 shows the pH of the aqueous extracts of the sulphamic acid treated wools.

It can be seen from the results given in Figure 2.4 that, irrespective of the extraction method (Test A, Test B, Test C), there is a significant difference between the pH of the extracts from the 150°C cured sulphamic acid treated wool and extracts from the 100°C and 125°C cured sulphamic acid treated wools.

In the actual dyeing procedure, the pH variations are also consistent with the aqueous extraction data for sulphamic acid treated wool (Figure 2.5). All treated samples exhibited lower pH values than those for untreated

54 Chapter 2 Dye Resist Effects

Exhaustion(%) 100 ,------__..,..* _____- ____- ____- ____- ____- ____---,_* ____ - ____- ____- ____- ____- ____---, ______==---~ D 80

60 D

40

20 0 -·* __ A------/::;;.

0 ~-=C::::::~=~=~==:..i:s.:=:.::C.:.::.:.::.:t:.._----1...._ _l__.L....____j__ _J 0 2 4 6 8 10 12 Time (v't) v'min

Untr~ated 100~9.*C?.~ring 125°9.Ef~ring 1so:9_zf_~ring Figure 2.11. Rate of Lanasol Type Exhaustion on Sulphamic Acid treated Wool Chapter2 Dye Resist Effects

Exhaustion (%) 100 .------, *--····· G--············· ·D 80 ______/:::,. 60 /k-- , , , , , , 40 / 0 , , IJS.' .. --··············* --- 20 __ ... ------~·:·· ..... ··········· --- <<~ ______.,a--- o~::.;;__..______,1,_---J..._.....L..._....1.-_.L.----J_---L._---1...._...1..-_..1.-_L...-----1 0 2 4 6 8 10 12 Time (vt) vmin Unt~ated 100:9.*(?.~ring 125°9.Ef-~ring 150:9~-~rlng Figure 2.1 O. Rate of lrgalan Type Exhaustion on Sulphamic Acid treated Wool Chapter2 Dye Resist Effects

Exhaustion(%) 100 ,------,,-~

80

60

40

20 .. -··*

···········•~t_· ______~------A------6

0l!t"-~=.::...... !:::l::...------L----l...---L..----'---...J..._-..J...-_J....._____J_---'----1-----1 0 2 4 6 8 10 12 Time (vt) vmin

UntrBated 100~(?.*(?.~ring 12s0 98~ring 1so:9,i_~ring Figure 2.9. Rate of Cl Acid Red 41 Exhaustion on Sulphamic Acid treated Wool Chapter2 Dye Resist Effects

Exhaustion {%) 100 r------r,s:::===~a.::::=:....=-----=----·=····.;:;;···=-r--, __ ... -----·

80

60 D

40 D .-·· ·* 20 ·-···················*···················· ------A ------~ 0 IIP"'----""""'--.....til~i.:..:..ia.a=====n.:...__J_ _i.._ ___.,L__....L.-_..J...___L.._____J 0 2 4 6 8 10 12 Time {vt) vmin

Unt~ated 100~9.*~~ring 125°98.~ring 1so:9~-~ring Figure 2.8. Rate of Cl Acid Red 27 Exhaustion on Sulphamic Acid treated Wool Chapter2 Dye Resist Effects

Exhaustion {%) 100 ,------~======i~=====~~----········------· D 80

60 0

40

20

... ···········:·:·:. ---8------A------6

2 4 6 8 10 12 Time {vt) vmin Untr8ated 100~9*(?.~ring 125~~rlng 1so:9,i_~ring Figure 2. 7. Rate of Cl Acid Red 44 Exhaustion on Sulphamic Acid treated Wool Chapter 2 Dye Resist Effects

Exhaustion (%) 100 .------~

80

60 . H __ j9_ o---- _A----­ _,, / 40

20 -·-*

0 2 4 6 8 10 12 Time (vt)

Untr~ated 100~9.*9.~rlng 125°(?0(?~rlng 150~9£~rlng

Figure 2.6. Rate of Cl Acid Red 88 Exhaustion on Sulphamic Acid treated Wool Chapter 2 Dye Resist Effects wool in the dyeing liquor. The 150°C cured sulphamic acid treated wool has a fairly stable pH of circa 4.5 during the dyeing cycle. Hence it would appear that all of the sulphamic acid in the wool is bound acid. For the case of the 100° C cured sulphamic acid treated wool, the pH of the dyebath initially drops to ea 28 and continues to fall during the dyeing cycle. Hence free sulphamic acid is being desorbed from the wool, suggesting that the sulphamic acid is not bound to the wool when cured at 100°C. The 125°C cured sulphamic acid treated wool behaves as if the sulphamic acid has partially fixed to the wool.

2.2.3.3. Dye Exhaustion Curves

In order to elucidate the curing mechanism of sulphamic acid treated wool, the dye exhaustion curves were compared

After examining Figures 2.6 - 2.11, it can be seen that the exhaustion curves can be divided into two groups; namely Figures 26 - 2.9 and Figures 2.10 - 2.11. In the former group, all cured samples exlubit dye resist effects, while in the latter group, low temperature cured sulphamic acid treated wool exhibits dye assist effects, whereas high temperature cured sulphamic acid treated wool exlubits dye resist effects.

Sulphamic acid is a white crystalline solid which melts with decomposition at 205°C [129]. Several studies of the crystal structure

55 Chapter 2 Dye Resist Effects have been carried out [130,131] and show that sulphamic acid exists in the zwitterion form, +NH3SO2O·, rather than in the uncharged acid form. The zwitterionic state is also present in aqueous solutions [131].

At room temperature, aqueous solutions of sulphamic acid are very stable, although at elevated temperatures rapid hydrolysis occurs as follows [132].

Decomposition tends to be very rapid above 136° C while, at lower temperatures, decomposition proceeds more slowly [133]. Thus the decomposition temperature of sulphamic acid has a close correlation with the extent of the dye resist effect achieved in wool. The pyrolysis of sulphamic acid results in a whole series of sulphamides, sulphonic acids and polysulphimides [134], and it is also possible that sulphamic acid decomposes to sulphur trioxide and ammonia [135]. The reaction formulae may be represented as follows:

HOSO2NH2 + NH2SO2OH ----> NH(SO2OH)2 + NH3 (2-1) NH2SO2OH + NH2SO2OH ----> HOO2S-NH-SO2NH2 + H2O (2-2) 3NH2SO2OH ----> (NHSO2)J + 3 H2O (2-3) (2-4)

56 Chapter2 Dye Resist Effects

0 le o-,t~- 0=5=0 Step : 0 1 = S + W - NH2 -- ~ 0 c5- W-N-Hin I H An ammonium Ion W-NHS~ + rt€>

Step2: W-NHS~ + H$ --- W-NHS0:3H W=Wool

Figure 2.12b. Reaction Mechanism of Sulphur Trioxide And Basic Amino acid groups of wool. Chapter 2 Dye Resist Effects

0 I O=-S-o .. I~) STEP 1: + W--OH - W-O-H ·. r}- An oxonium ion

---w-Q-SQG + ~ .. 3

G G STEP 2: w-o-so3 + H -- w-o-soH3 W == WOOL

Figure 2.12a. Reaction Mechanism of Sulphur Trioxide and Hydroxyl Amino acid groups of Wool. Chapter 2 Dye Resist Effects

where sulphamic acid can be expressed as NH2S020H or as +NH3-SOi, the zwitterionic state mentioned above.

In dye resist treatments using sulphamic acid, owing to the high curing temperature (150° C), sulphur trioxide and ammonia reaction products (2-4) would predominate, although all the reactions (2-1, 2-2, 2-3) would partially participate. In reaction (2-4), the ammonia would be given off as gas, but the sulphur trioxide would participate in the subsequent reaction. At the same time, around this temperature, destruction of some amino acids will occur. It is well known that amino, amide and disulphide groups and many other amino acids including aspartic acid, threonine, serine, valine, tyrosine, lysine, arginine and histidine are partly destroyed by heat [136]. Actually, the presence of the formation of a O-serine hydrogensulphate peak was confirmed in the amino acid analysis of the sulphamic acid treated wool by Cameron [137]. Therefore these amino acids and sulphur trioxide would react with each other covalently.

The reaction mechanisms can be postulated as is shown in Figure 2.12a and Figure 2.12b.

In this reaction, sulphur trioxide acts as a Lewis acid because the sulphur atom is slightly electron deficient, whereas oxygen atoms have a slight excess of negative charge due to the difference in electronegativity of oxygen and sulphur. Therefore in step 1, SO3, which is Lewis acid, would

57 Chapter 2 Dye Resist Effects react with Lewis bases such as the hydroxyl amino acid group or the basic amino acid group which have unshared electron pairs on the oxygen or on the nitrogen, to form an oxonium ion or an ammonium ion respectively as transition states W-O+H-S03 or W-N+H2S03.

As the transition states are unstable, the oxonium ion or ammonium ion would immediately gain electrons from the hydrogen, and they would then reach a stable state as wool sulphonate and wool sulphamate groups respectively.

Hence, below 136° C, sulphamic acid may be difficult to decompose to sulphur trioxide and so it could exist as an unreacted free sulphamic acid on the wool surface. Therefore the amount of free sulphamic acid might increase· as curing temperature decreases.

These assumptions can be explained as follows. When the dye exhaustion curves (Figures 2.6 - 2.9) for 100° C cured sulphamic acid treated wool are examined, for dyeing under strong acid conditions, the unbound free sulphamic acid would not significantly affect the dyebath pH, however, when dyeing under weak acid conditions (Figures 2.10 - 2.11) the dyebath pH would decrease significantly owing to the desorption of the unbound free sulphamic acid. Therefore, in reactive dyeing or metal complex dyeing which is carried out in weak acid conditions, the exhaustion curves of 100° C cured sulphamic acid treated wool would show a high dye assist effect, and for 125° C cured sulphamic

58 Chapter 2 Dye Resist Effects acid treated wool, it would exhibit a slight dye assist effect depending on the dyestuff.

In fact, the resultant dyed samples of 100° C and 125° C cured sulphamic acid treated wool showed unevenness after dyeing. This fact also supports the above results.

Harris et al. [88] found good agreement between the rise in the measured alkali binding capacity and that calculated from the increase in weight expressed as S03 in concentrated sulphuric acid treated wool.

2.2.3.4. The Influence of Sulphonic Acid Groups

In order to investigate the influence of the sulphonic acid groups of dyestuffs, dye exhaustion curves on sulphamic acid treated wool were compared. According to Figures 2.6 - 2.11, as the number of sulphonic acid groups on the dyestuffs increases, the dye exhaustion decreases.

These results are consistent with that of Bell et al. [8]. They explained this by a hydrophobic mechanism. The ionic repulsion between the dye anions and the sulphate and sulphamate groups of the wool would become weaker compared with the hydrophobic forces which predominate over the dyes' affinity for the fibre [8]. Therefore, as the number of sulphonic acid groups in the wool increases, the wool would

59 Chapter 2 Dye Resist Effects

;_ ..,.

------~-=------, _.--- I

_.-·· .. ,. ____ ... -- - , . - r ------

E E E - ...

* Treated: Control:

Figure 2.17c. Reflectance Cune of Lanasol Red Type (Curing 150°C) Chapter 2 Dye Resist Effects

.;. I

------.L

r.

.-.------:--.:·:-:-_--:--::--:-:----.. __ _ - ·::--- ···;!'"-:~-~--.,.__------~--- ,A... .,,. .. - E E E

i.;: '

* Treated: Control:

Figure 2.17b. Reflectance Curve of Lanasol Red Type (Curing 125°C) Chapter 2 Dye Resist Effects

- -·

____ ... ------

------~~..:..------. -.. ___ _ ------.:.:.:.:...:..:..:..:_:_ ___ .- E = =

i.:-

* Treated: Control:

Figure 2.17a. Reflectance Curve of Lanasol Red Type (Curing 100°C) Chapter 2 Dye Resist Effects

------:-:-:~ ------

__ .. -

.---· .-··

·.;, ':;_!. ·-. ____ _ , '

E E

-::

* Treated: Control:

Figure 2.16. Reflectance Curve of Cl Acid Red 41 (Curing 150°C) Chapter 2 Dye Resist Effects

------

.----- .------

------

* Treated: Control:

Figure 2.15. Reflectance Curve of Cl Acid Red 27 (Curing 150°C) Chapter 2 Dye Resist EtJects

------

,.

------

E ,::" .-. - if l.-

* Treated: Control:

Figure 2.14. Reflectance Curve of Cl Acid Red 44 (Curing 150°C) Chapter 2 Dye Resist Effects

:,.. g

':_:,: -- _..,,...------­ _.-~·=--,-;;-- />'' . /:' 0 /,.··; I I , / ,·' - - .//

- ·- = -~ = =

·=,;-

* Treated: Control:

Figure 2.13. Reflectance Cuffe of Acid Red 88 (Curing 1S0°C) Chapter 2 Dye Resist Effects become more hydrophilic in character while the hydrophobic forces would decrease.

Therefore, as the hydrophilic character of dyestuffs increase, the ionic repulsion between the anionic wool fibres and the dyestuffs would increase while the hydrophobic forces would decrease, and these changes would make the wool dye resistant.

To illustrate these effects, the reflectance curves for dyed sulphamic acid treated and untreated wool were recorded for dyes varying in hydrophobic/hydrophilic character.

It can be seen from the data in Figure 2.13 to Figure 2.16 that, as the number of sulphonate groups increases from 1 to 4 (Cl Acid Red 88 - Cl Acid Red 41 ), the dye resist effect substantially increases.

For the Lanasol Red-type dyestuff (Figure 2.17) it can be seen that a dye resist effect is only achieved when the sulphamic acid treated wool is cured at 150°C. This result would indicate that 150°C curing is necessary to block the nucleophilic sites required for the fixation of the reactive dye to wool.

It is interesting to compare the dye resist effects for Cl Acid Red 1 and Cl Acid Red 138. These dyes have the same structure except that Cl Acid Red 138 has a dodecyl group and hence is much more hydrophobic

60 Chapter 2 Dye Resist Effects

.,;.

/ ., - . - . - - - . - -~~~~----~:-~:-:-:------·· - - E - - ' ' ' -.

* Treated: Control:

Figure 2.19c. Reflectance Curve of lrgalan Type (Curing 1S0°C) Chapter 2 Dye Resist Effects

t:,

\:".

--._------.. - .. - . ~..:-.------=-··:--::-·.

E

;:_

* Treated: Control:

Figure 2.19b. Reflectance Curve of lrgalan Type (Curing 125°C) Chapter 2 Dye Resist Effects

=-=--=-:..:...:_...:,_ -

.-. -0

* Treated: Control:

Figure 2.19a. Reflectance Curve of lrgalan 'fype (Curing 100°C) Chapter 2 Dye Resist Effects

..------

/ ,,

i ' ------. ------.... _ _... ------I _... - ·------,, I· .. -- -- .------

E E E E E

....

* Treated: Control:

Figure 2.18b. Reflectance Curve of Cl Acid Red 138 (Curing 1S0°C) Chapter 2 Dye Resist Effects

i.:'"; I ' ------____ .---

. t ' .------· .------.------.. ___ _

- f.:

E E E E

...::

* Treated: Control:

Figure 2.18a. Reflectance Curve of Cl Acid Red 1 (Curing 150°C) Chapter 2 Dye Resist Effects in character than Cl Acid Red 1. It can be seen from the data in Figure 2.18 that a greater dye resist effect is achieved for Cl Acid Red 1. Obviously hydrophobic forces play a greater role in dyeing with Cl Acid Red 138.

When dyeing with the Irgalan -type dyestuff (Figure 2.19a - Figure 2.19c), a dye which has no sulphonate groups, very little dye resist effect is achieved even when the sulphamic acid treated wool is cured at 150° C. Therefore one must conclude that sulphamic acid does not change the hydrophobic dyeing mechanism. Hence the hydrophobic character of both the dyestuff and the wool play an important role in the achievement of a dye resist effect.

The dyeing process involves three principal components, dyestuff, substrate and water. Hence, in order to understand the overall process, one must elucidate the extent of the interactions between them. Although much work [138,139,140] has been done to give some guidelines in this area, this subject has not yet been completed and is still being studied.

2.2.3.5. Quantification of the Relationship of Dye, Water, Substrate.

Most dyeing is conducted in water because water is still by far the least

61 Chapter 2 Dye Resist Effects expensive solvent. Every dyeing process involves a substrate, a dyestuff and a solvent For cost reasons water is usually preferred to other solvents in normal dyeing. Therefore water is the most important system not only in dyeing but also in textile wet processing.

Fujita [141] has proposed that it is possible to predict the characteristics of organic compounds using the concept of inorganicity and organicity. Recently these theories have been applied to the study of dyeing properties, and to the analysis of the experimental results in relation to dye structure and reactivity [142,143].

2.2.3.5.1. HLB Method

The first and simple trial of the relative ratios to compare with water is the HLB method. The hydrophile-lipophile balance (HLB) is an expression of the relative simultaneous attraction of an emulsifier for water and for oil. This method is still used in the surfactant industry and was developed by the Atlas Powder Company [144]. It assigned 1 as the HLB number of oleic acid and 20 to potassium oleate. It is mainly based on experimental emulsification data.

2.2.3.5.2. IOR Method

Fujita [141] proposed the concept of the ratio of inorganicity to

62 Chapter 2 Dye Resist Effects

DYE DYE CURING TEMP IOR RESIST (OC) (%)

CI ACID 100 34.68 RED88 125 2.5 45.78 (1 x SOi)

100 30.45 CI ACID RED44 125 4.4 43.44

(2 X SO3-)

100 29.56 CI ACID RED27 125 6.3 42.24

(3 X SO3-)

CI ACID 100 25.48 RED41 125 8.1 90.33 (4 X SO3-)

Table 2.2(a). Dye Resist Effects Chapter 2 Dye Resist Effects organicity of organic compounds. The ratio of inorganicity to organicity (IOR) can be widely used to numerically describe the primary properties of organic compounds such as solubility or melting point. Details are descnbed in Appendix I.

2.2.3.5.3. QSAR Method

Since the introduction of the Hammet equation in 1935, much work about correlating structure with reactivity has been done at an increasing rate. This work has originated from pharmaceutical science which aims to synthesise the optimum drug. The subject has now been named as the

"Formulation of Quantitative Structure Activity Relationships" or QSAR.

Such QSAR has shown the importance of the correlation of chemical structure with biological activity to provide an insight as to how and why a substance has its effect and to predict the chemical structures that have higher effectiveness [145,146].

Among these methods, the IOR values can easily be calculated from contributions assigned to the various functional groups. The IOR calculations were compared with the dye resist results.

Table 2.2(a) gives the dye resist values and IOR values for the acid dyestuffs employed in this study.

63 Chapter 2 Dye Resist Effects

100 ···························································· . : ····-0 ...... 95%

a:I 50 '#.

0 ---.-----.--....--~---r--~.-----.--.....------.--, 0 5 10 IORValues

Figure 2.20. % Resist on 150°C cured wool versus IOR values Chapter 2 Dye Resist Effects

CURING DYE DYE Temperature IOR RESIST (OC) (%)

100 -56.78 IANASOL 125 3.6 8.20 TYPE

100 -15.76 IRGALAN 125 1.3 10.54 TYPE

100 28.76 Cl ACID 125 5.3 62.75 REDl

100 -20.56 Cl ACID 125 3.2 32.56 RED 138

Table 2.2(b ). Dye Resist Effects Chapter 2 Dye Resist Effects

It can be seen from the results that the IOR values correlate with both the number of sulphonic groups on the acid dyes and the dye resist effect These results show that the dye resist effect is highly correlated with the hydrophilic and hydrophobic character of the dyestuffs.

The structures of Cl Acid Red 1 and Cl Acid Red 138 are essentially the same except that Cl Acid Red 138 contains a dodecyl group thereby making it more hydrophobic than Cl Acid Red 1.

The data given in Table 2.2(b) reflects this difference in hydrophilic/hydrophobic character with Cl Acid Red 1 and Cl Acid Red

138 having IOR values of 5.3 and 3.2, respectively. It can also be seen in Table 2.2(b) that the lrgalan dyestuff used in this study is the most

"hydrophobic" dye in the set with an IOR value of 1.3. The IOR value of the Lanasol dye falls between that of Cl Acid Red 88 and Cl Acid Red 44.

These results demonstrate that the dye resist effect achieved with the sulphamic acid process is highly dependent on the IOR values of the dyes employed to dye the sulphamic acid treated wool. The % resist

(150°C cured) versus IOR value data for the dyes employed in this project that dye wool by ionic/hydrophobic mechanisms (i.e. excluding the Lanasol reactive dye) are plotted in Figure 2.20. It can be readily seen that, in order to achieve dye resist values of greater than say 95%, the dyestuffs employed in the dyeing must have IOR values greater than

64 Chapter 2 Dye Resist Effects circa 5.5. Such dyestuffs are, of course, polysulphonated and hence more hydrophilic in character than the dyes that are poorly resisted by the sulphamic acid treated wool.

Sulphamic acid is a very effective resist for reactive dyes (e.g. Lanasol dyes) because the sulphamic acid treatment effectively blocks the nucleophilic sites in the wool and hence prevents fixation of the dyes to the wool.

2.3. Conclusions

The dye resist effects for sulphamic acid treated wool fabric observed by Cameron et al. [125] were confirmed

The best dye resist effect is achieved for acid dyes by curing at ea. 150° C. Below this temperature, a dye assist effect is exhibited for reactive and metal complex dyestuffs due to the characteristics of sulphamic acid itself although the extent of the dye resist effect depends upon the dyestuff.

The dye resist effect is highly dependent on the hydrophilic/hydrophobic character of the dyestuffs and substrate. With the exception of reactive dyes, this work shows that the IOR values of the dyes should be greater than 5.5 in order to achieve dye resist values of better than 95 % on

65 Chapter 2 Dye Resist Effects sulphamic acid treated wool. It will be necessary in future work to consider the hydrophilic/hydrophobic character of both the substrate and dyestuffs in order to fully understand dye resist effects on wool.

IOR values can be used as an important tool in the evaluation of the hydrophilic/hydrophobic character of dyes. This technique should be of great value in future work on dye resist processes.

The main thrust of future work therefore must be to find the conditions under which a dye resist agent can be completely cured and bound to the wool in order to achieve good dye resist effects.

66 CHAPTER 3. PREPARATION AND APPLICATION OF REACTIVE

DYE RESIST AGENTS

3.1. Introduction

From the results of the experiments described in Chapter 2, it was concluded that a viable dye resist agent must be completely cured and bound firmly to the wool substrate in order to achieve satisfactory dye resist effects.

We now know that the treatment of wool with sulphamic acid requires a high curing temperature for the sulphamic acid to be completely cured to the wool substrate owing to the low fixation of sulphamic acid to the wool substrate at low temperature.

Increasing the substantivity between the substrate and the dye resist agents is one of the most important factors needed to improve dye resist effects. In order to increase this substantivity, one possible effective dye resist method would be to covalently bind dye resist agents to the wool substrate using suitable fibre reactive groups.

Therefore, as was pointed out earlier in Section 1.6.2, a suitable model structure for reactive dye resists can be proposed as follows:

67 Cbapter3 Preparation and Application of Reactive Resists

X----NH----Ar---[ (S03)"] D where X represents a suitable fibre reactive group, NB is a bridging group, Ar is an aryl group, and S03 functions both as a water solubilising and an anionic dye "repelling" group.

If X ( reactive group) can be reacted and cured at low temperature, then these reactive resists should exhibit a low temperature curable dye resist effect. Thus the research aim was shifted to develop effective fibre reactive groups that are curable at low temperature.

The cold pad batch process, developed by Lewis and Seltzer [121 ], allows dyeing to be carried out at low temperature with the very reactive s-triazine based fibre reactive dyestuffs. This process may be applied to wool under mildly acidic conditions, in order to minimise the hydrolysis of dichlorotriazine dyestuffs, giving high fixation efficiency. Based on this process, it was considered that a low temperature curable dye resist effect may be similarly achieved by treatment of wool with a s-triazine based fibre reactive agent in a cold pad batch process.

Preliminary work, however, utilising several s-triazine derivatives indicated that a perfect dye resist could not be achieved with a monofunctional resist agent. Therefore, in order to achieve a more effective resist, a bifunctional system containing two s-triazine ftbre reactive moieties was designed and synthesised The resist effects

68 Chapter3 Preparation and Application of Reactive Resists

CI Dr - NH + Cl -

CI Dr - NH -

Dr: Dye Resist Group

::::::::J : s-Triazine

Figure 3.2. Synthesis Route for Reactive Resists Chapter 3 Preparation and Application of Reactive Resists

Cl)-- N1 N~ NH -/o'-soH \=.NI ~ 3 Cl/

ORM (I)

Cl"" _/ Cl ~N\\ NrNj ' NH -@/-Q NH 1/ N "=.N Nd Cl / SO H "" Cl 3

ORB (IQ

SOH 3

SOH 3 DRS (Ill) ORN (IV)

Figure 3.1. Chemical Structures of Reactive Resists Chapter 3 Preparation and Application of Reactive Resists

STRUCTURE CODE NAME *

ORM 2,4-Dichloro-s-triazin-6-yl-p- I aminophenyl-sulphonic acid sodium salt

ORB 2,5-Bis(2,4-dichloro-s-triazin- II 6-yl)-aminophenyl-sulphonic acid sodium salt

DRS 2,4-Dichloro-s-triazyn-6-yl-p- III aminosalicylic acid sodium salt

ORN 2,4-dichloro-s-triazin-6-yl- IV amino-8-naphthol-3,6- disulphonic acid sodium salt

* See Figure 3.1

Table 3.1. The Codes for and Chemical Names of Reactive Resists Chapter 3 Preparation and Application of Reactive Resists achieved were evaluated for each compound synthesised. Table 3.1 gives the codes and chemical names of the four synthesised reactive resists employed in this work. The chemical structures of the four reactive resists are given in Figure 3.1. The general synthesis route for the four reactive resists is shown in Figure 3.2.

3.2. Preparation and Application of s-Triazine based Reactive Resists

3.2.1. Materials and Methods

3.2.1.1. Materials

The wool fabric used in this work was a scoured and decatised 2/2 twill, weight 270 g/m2, supplied by John Vicars Fabrics, Sydney. 2,5-Diamino benzene sulphonic acid (90% assay), cyanuric chloride (99% assay) and sulphanilic acid (99% assay) were supplied by Aldrich. All other chemicals employed were of analytical grade. Lissapol TN 450 was supplied by ICI Australia Ltd.

3.2.1.2. Dyes

Three additional dyes were selected for study (in addition to the dyes used in Section 2.2.1.2.1) as shown in Table 3.2.

69 Cbapter3 Preparation and Application of Reactive Resists

Colour Index Name Commercial Name Dischargeability

Cl Acid Green 25 Solway Green GS Poor

Cl Reactive Red 116 Lanasol Red 2G Poor

Cl Reactive Blue 69 Lanasol Blue 3G Not Dischargeable

Table 3.2. Additional Dyestuffs Selected

The three dyes were chosen because they are classified as having " poor dischargeability" or as being "not dischargeable" in the Colour Index [127]. As mentioned earlier in Section 1.1, these types of dyestuff can be applied in dye resist methods. Therefore it was considered necessary to confirm whether these dyestuffs can be successfully applied in reactive resist processes. The three dyes were purified by the method descnbed in Section 2.2.1.2.2

3.2.1.3. Purification of Chemicals

Cyanuric Chloride (147]

Cyanuric chloride was crystallised from petroleum ether (b.p. 90-100°C), and dried under vacuum at room temperature.

70 Chapter 3 Preparation and Application of Reactive Resists

Sulphanilic Acid [148]

100 g sulphanilic acid in about 500 ml 1 N sodium carbonate solution was boiled, then filtered and made strongly acid with hydrochloric acid The solution was then neutralised with lN sodium carbonate. The hot solution was cooled to 0° C with stirring and the precipitate of sodium sulphanilate was filtered off. The crystals were dissolved in 500 ml distilled water and the solution was filtered and then acidified with cone hydrochloric acid . The material was then recrystallised from hot distilled water and dried at 120° C overnight.

l-Amino-8-naphthol-3,6-disulphonic Acid (ANDA) [149]

Sodium carbonate (20 g), to make the solution slightly alkaline to litmus, was added to a solution of 100 g of the dry ANDA in 750 ml of hot distilled water, followed by 5 g of activated charcoal. The suspension was stirred for 20 min and filtered by suction. The ANDA was precipitated by adding approximately 50 ml of cone. HCl, then filtered by suction and washed with distilled water. This purification procedure was then repeated. The ANDA was dried overnight in an oven at 60° C and stored

in a dark glass bottle.

71 Chapter 3 Preparation and Application of Reactive Resists

3.2.1.4. Synthesis of 2,4-Dichloro-s-triazin-6-yl-p-aminophenyl­ sulphonic acid sodium salt (dihydrate) (DRM)

DRM is also known commercially as Sandospace R (Sandoz). However the product had been withdrawn from sale due to health hazards. Thus DRM was synthesised for use in this project. Subsequently, Sandospace R was reformulated as a paste and is currently available from Sandoz.

The method used was based on that described by Lewis and Pailthorpe [6]. Sulphanilic acid (26 gas a slurry in 100 ml water) was added slowly to cyanuric chloride (28 g as a slurry in 200 ml acetone containing about 100 g ice), whilst maintaining the pH of the solution at 7 by the addition of 2N sodium hydroxide. The reaction mixture was stirred for 1.5-2.0 hours after which time the reaction was judged to be complete once the pH had stabilised at 7. The product was filtered off, washed thoroughly with acetone and then oven dried (yield 92% ).

3.2.1.5. Synthesis of 2,5-Bis(2,4-dichloro-s-triazin-6-yl)­ aminophenyl-sulphonic acid sodium salt (dihydrate) (DRB)

Cyanuric chloride (37 g) in acetone (200 ml) and ice was added to a solution of 2,5- diamino benzene sulphonic acid (19 g) as a slurry, whilst maintaining the pH at 7 by the addition of a solution of saturated sodium carbonate. Stirring was continued for 3 hours and the reaction

72 Chapter 3 Preparation and Application of Reactive Resists was monitored by TLC. On completion of the reaction the precipitate was filtered off, washed thoroughly with acetone in order to remove any excess cyanuric chloride, and then dried to constant weight. The yield was 90%.

3.2.1.6. Synthesis of 2,4-Dichloro-s-triazin-6-yl-p-aminosalicylic Acid Sodium Salt (Dihydrate) (DRS) [8]

Cyanuric chloride (32 g) was dissolved in 100 ml acetone, ice cold with constant stirring, to which was added 25 g of the sodium salt of p­ aminosalicylic acid dissolved in 60 ml water, while slowly adding a saturated solution of sodium carbonate and ensuring that the pH did not rise above at 7.0. At the end of the reaction (when the pH was stable and the test for p-aminosalicylic acid (TLC) was negative), the contents of the reaction vessel were filtered off and washed thoroughly with acetone in order to remove excess cyanuric chloride. The product was dried to constant weight. The yield achieved was 97%.

3.2.1.7. Synthesis of 2,4-Dichloro-s-triazin-6-yl-amino-8-naphthol-3,6- disulphonic Acid Sodium Salt (DRN) [150]

38 g ANDA (H Acid) was dissolved in lN sodium bicarbonate solution, the solution was diluted to 500 ml and neutralised with acetic acid. This

73 ChapterJ Preparation and Application of Reactive Resists solution and 2N sodium carbonate solution were dropped simultaneously into a well stirred suspension of finely divided cyanuric chloride (20.2 g) in acetone and ice water (100 ml 1:1) at 0°C over 3 hrs. After the reaction was complete ( when pH was stable at 7 and the test for ANDA (TLC) was negative) the mixture was filtered, the residue was rotary evaporated to reduce the solvents at 40° C and was salted out using saturated NaCl solution. The product was filtered and vacuum dried at room temperature. The yield achieved was 70 %.

3.2.1.8. Characterisation of Products

Melting points were determined on a Gallenkamp Melting Point Apparatus. IR spectra were recorded on a Hitachi Model 260-10 Infrared Spectrophotometer and referred to Nujol mulls mounted onto a disc of NaCl. Elemental analyses were conducted by the School of Chemistry, University of New South Wales. Thin layer chromatography (TLC) was carried out using Merck 60F~ Silica Gel TLC Foils. A variety of eluents including acetone, water-saturated butanol and ethanol were used. The chromatograms were visualised at 254nm with a Universal UV Lamp (CAMAG Muttenz Schweiz).

3.2.1.9. Application of Resist Compounds

74 Chapter 3 Preparation and Application of Reactive Resists

The four reactive resists were applied to wool fabric (3 g) by a pad-cure technique. The treatment solution contained: active compound X % wt/wt, sodium acetate 10% wt/wt, urea 20% wt/wt and Llssapol TN 450 0.1 % wt/wt. The fabric was impregnated and passed through a vertical pad mangle (Konrad Peter AG.) set to achieve approximately 70 % wet pick-up, then batch-rolled around a small cylinder, sealed in a polythene bag and cured for a specific time and temperature. The samples were washed off for 30 minutes in running tap water at 50° C and then dried.

The same compounds were also applied to wool fabric by an exhaustion method derived from that of Sandoz [151] and that of Bell et al. [8].

Active Compound x % o.w.f. Sodium Sulphate (anhydrous) 10 % o.w.f. Acetic Acid 1 % o.w.f. ( adjust to pH 4.5) Llssapol TN 450 0.1 % o.w.£

The wool samples were entered at 20° C into the bath containing the above chemicals and run for 10 min, the temperature was then raised to 40°C over 10 min after which time the temperature was raised to 100°C over 60 min and held for the required fixation time. After fixation, the fabric was soaped cold in 0.1 % Llssapol TN 450 for 10 min and then washed off with warm water until free from foam.

The exhaustion application method was quite successful however the

75 Chapter3 Preparation and Application of Reactive Resists weight gains achieved were slightly less ( circa 2 % ) than the weight gains achieved by the pad-cure application method These samples were used in the stain blocking experiments which are described in Chapter 4.

3.2.1.10. Determination of Weight Gain

Weight gain was determined on the basis of oven dry weight measured before and after the application of the reactive resist compound Fabrics were dried to constant weight in a circulating oven at 90° C for 2 hours.

3.2.1.11. Dyeing of Wool Fabric

The dyeing method employed is described in Section 2.2.22. In order to compare the dye resist effects, competition dyeings were also carried out with a 2: 1 ratio of untreated to treated wool. The dyed pieces were then washed-off at 50° C and dried.

3.2.1.12. Evaluation of Dye Resist Effect

The degree of dye resist achieved was calculated as previously described in Section 2.2.2.5.

76 Chapter 3 Preparation and Application of Reactive Resists

Product Yield Elemental Composition IR(cm·1) Code (%) C H N

DRM 92 [E] 27.40 1.72 21.30 1180,1560, [F] 27.53 1.84 21.25 3300

DRB 90 [E] 28.51 2.39 14.78 1190,1560, [F] 27.50 2.20 13.61 3400

DRS 97 [E] 33.45 2.53 15.60 1190,1570, [F] 33.10 2.94 14.57 3300

DRN 70 [E] 33.42 1.72 11.99 1180,1560, [F] 32.98 1.31 11.45 3300

[E] : Expected Value [F] : Found from Elemental Analysis

Table 3.4. Elemental Analyses and IR Data Chapter 3 Preparation and Application of Reactive Resists

Condition Reaction Reactants pH Temp Time

Cyanuric Chloride: 1 mol Primary 1½-1¾ Amino Aromatic 7 0°C Condensation Hrs Sulphonic Acid: 1 mol

Cyanuric Chloride: 1 mol Secondary 35°- Amino Aromatic 7 l½Hrs Condensation 45°c Sulphonic Acid: 2 mol

Cyanuric Chloride: 1 mol Tertiary goo_ Amino Aromatic 7 2½Hrs Condensation 100°c Sulphonic Acid: 3 mol

Table 3.3. Preparative Conditions of Condensation Products [150] Chapter 3 Preparation and Application of Reactive Resists

3.3. Results and Discussion

3.3.1. Synthesis

Although a number of patents and journal articles [109,110,150,152] describe the synthesis methods which condense cyanuric chloride to amino aromatic sulphonic acids, it was found that the published procedures did not give satisfactory results. Therefore the methods developed in this work were based on optimisation according to the claims of each patent and journal article and preliminary experiments. The published conditions are summarised in Table 3.3.

3.3.2. Characterisation of Products

All compounds have melting points above 250° C. Some products were analysed as the dihydrate. The structures of the synthesised compounds were confirmed by elemental analysis and IR spectroscopy. The strong bands at 2900, 1470 and 1370 cm-1 and a weak band at 720 cm-1 were ignored because of Nujol oil bands [153]. The results from the elemental analyses and appropriate IR spectral data are given in Table 3.4. The IR spectra are given in Figures A3.1 to A3.4 of Appendix II. The data from elemental analyses and IR spectra showed that all four synthesised products were in good agreement with the expected values. Ring stretching modes were observed for the triazine functional group

77 Chapter3 Preparation and Application of Reactive Resists

Weight gain % 12 .------~

- - - •------4. 10

, ..O··················O··················O 8

6 __ .. · --*----"* -* _____ '!" .-- o· ..i.-- 4 ,,--- .. ·· ,, ,, ,, ,, . 2 _,, o·· .·· .... ,, ---*"' .. ·.,..<·;·A" -- ,, o ____..;;,; ., ____,______.__ ___..______._ ____.______. 0 5 10 15 20 25 30 Quantity applied (%wt/wt.solution) ~-'i~ ~ .~~~ ~~~ Figure 3.3. Weight Gain vs Amount of Dye Resist Compound applied by the Pad-Cure Method with fixation at 80°C and 24 hours Chapter3 Preparation and Application of Reactive Resists

at 1560-1520 cm-1 [154]. This result clearly indicates that all four compounds have a triazine group.

3.3.3. Weight Gain

The weight gains achieved when the synthesised reactive resist compounds are applied to wool by the pad-cure method are given in Figure 3.3. For all four reactive resists, the maximum weight gain appears to be achieved at an application level of about 14 % owf (20 % wt/wt, 70 % wet pick-up). DRB achieved the highest weight gain of ea. 11 %, whereas DRM achieved ea 10 %. The weight gains achieved with DRS and DRN were only circa 8 % and 5 %, respectively.

In an attempt to explain the weight gain results for DRB, DRM, DRS and DRN, the IOR values of synthesised compounds were calculated and are given Table 3.5.

CODE IOR Value

DRB 7.54

DRM 6.96

DRS 5.96

DRN 8.65

Table 3.5. IOR Values of Reactive Resists

78 Chapter 3 Preparation and Application of Reactive Resists

DIFFERENCES OF CHARGE HETERO CYCLES DENSITY

Pyridine 0.149, 0.090, 0.121

Pyridazine 0.098, 0.068

Pyrimidine 0.213, 0.186, 0.086

Pyrazine 0.120

s-Triazine 0.233

Table 3.6. Differences in Charge Density Distributions between Carbon and Nitrogen Atoms in Heterocycles Chapter3 Preparation and Application of Reactive Resists

01.0100.979 0.951 1.100 Pyridine 00.~70.987 0.926

1.055 0°-~1.112 0°-~1.080 Pyrldazlne Pyrimidine Pyrazlne 01.11s 0.883 s-Triazine

Figure 3.4. Charge Density Distributions of Heterocycles Chapter3 Preparation and Application of Reactive Resists

It can be seen that the order of the weight gains is consistent with that of the IOR values of the reactive resists except for DRN, which gave the lowest weight gain yet has the highest IOR value. It must be concluded that other factors such as molecular configuration, in addition to ionic/hydrophobic mechanisms, could affect the achieved weight gains.

The pyrimidine reactive group, employed by Wang [155] in the synthesis of reactive hydrophobes, achieved a weight gain of ea. 8 % at an application level of ea. 20 % owf. The reason for these results can be explained as follows.

The inductive effect of the electronegative nitrogen in the heterocyclic ring systems can be recognised from the charge density distributions (Figure 3.4) which have been calculated for various nitrogen heterocycles by Peacock [156]. Using this data, the difference between the charge density of the nitrogen and that of the carbon atoms was calculated and the results are given in Table 3.6. The data shows that the s-triazine ring system has the most inductive effect of the electronegative nitrogen in the heterocyclic molecules examined.

Since the inductive effect of the electron-withdrawing nitrogen on the s­ triazines activates the reactive centres on the carbon atoms of s-triazines more than those of other heterocycles, it would be anticipated that the leaving groups in the s-triazines should be more easily substituted than those of other heterocycles.

79 Cbapter3 Preparation and Application of Reactive Resists

CPD MW WG% mmoVg mmoVg mmoVg SO3- coo-

DRM 331.12 10.6 0.32 0.32 - DRB 470.05 11.4 0.24 0.24 - DRS 323.08 8.3 0.26 - 0.26 DRN 511.23 5.3 0.10 0.20 -

CPD - Reactive Compound MW - Molecular Weight WG% - Weight Gain %

Table 3.7. Weight Gain Data Expressed as mmol/g Chapter 3 Preparation and Application of Reactive Resists

Moreover, the electronegativity of the leaving groups adjacent to the reactive centres also partly contribute to the increased reactivity of the reactive centres as illustrated in Figure 1.16a.

It can be seen from the results given in Figure 3.3 that the DRB treated wool achieves a higher weight gain than the DRM treated wool.

One might be tempted to deduce that this difference arises because the DRB reactive resist contains two s-triazine reactive moieties which leads to a higher degree of fixation of DRB to the wool fibre [157,158]. When the weight gain data is recalculated in terms of mi11imoles/g reactive resist fixed to the wool, a different pattern emerges. As can be seen from the data provided in Table 3.7, DRM has actually achieved the highest fixation of active compound.

Thus, since both DRM and DRB are monosulphonated species, DRM has actually introduced the greatest number of sulphonate groups into the wool. DRN is a disulphonated reactive resist and, even though the weight gain (5.3%) is lower than that achieved by DRB (11.4% ), the DRN modified wool has only slightly less sulphonate groups than does the DRB treated wool.

The DRS modified wool, with a weight gain of 8.3%, has 0.26 mmol/g of carboxylic acid residues. This concentration is similar to the number of sulphonate groups to be found in both the DRB and DRN modified

80 Chapter3 Preparation and Application of Reactive Resists

100

0

0 5 10 IORValues Competition Normal 0 * Figure 3.9. % Resist on DRN treated Wool (Weight Gain: 5.3 %) versus IOR values Chapter3 Preparation and Application of Reactive Resists

100

0

0

0

0 5 10 IORValues Competition Normal 0 * Figure 3.8. % Resist on DRS treated Wool (Weight Gain: 8.3%) versus IOR values Chapter3 Preparation and Application of Reactive Resists

100

0

:i 0 i a: 50 *-

0 * * 0 0 5 10 IORValues Competition Normal 0 * Figure 3.7. % Resist on ORM treated Wool (Weight Gain:10.6 %) versus IOR values Chapter3 Preparation and Application of Reactive Resists

100

0

0 I 50 '#-

*

0 ----,------,----.-----,-----.---r------r----r--,-----. 0 5 10 IORValues Competiton Normal 0 * Figure 3.6. % Resist on ORB treated Wool (Weight Gain: 11.4 %) versus IOR values Chapter3 Preparation and Application of Reactive Resists

0 5 10 IORValues Competition Normal 0 * * treated as In Section 2.2.2.1.(Curing Temp:150°C) Figure 3.5. % Resist on Sulphamic Acid treated Wool (Weight Gain: 8.5 %) versus IOR values Chapter 3 Preparation and Application of Reactive Resists

Cl Name IOR SA DRB DRM DRS DRN 8.5% 11.4% 10.6% 8.3% 5.3%

Cl Acid 8.1 C 99.6 93.5 91.4 88.2 76.6

Red41 N 98.5 69.4 55.0 47.3 35.5

Cl Acid 6.3 C 99.5 92.9 90.5 86.3 73.0

Red 27 N 95.3 64.3 51.3 428 31.5

Cl Acid 5.3 C 98.8 89.2 87.1 80.2 66.3

Red 1 N 94.5 58.4 47.3 38.3 28.9

Cl Acid 4.4 C 97.0 823 80.6 78.5 60.8

Red44 N 88.8 523 39.5 33.9 227

Lanasol 3.6 C99.6 93.6 91.4 89.5 84.2 Type N98.0 56.7 55.5 53.2 41.2

Cl Acid 3.4 C 99.5 91.1 90.2 80.5 59.4

Green25 N 94.5 50.5 49.3 38.7 26.2

Cl Acid 3.2 C 92.5 68.8 66.6 61.3 527

Red 138 N 77.2 43.1 31.3 25.0 18.9

Cl Acid 25 C 89.3 58.7 56.4 51.6 41.3

Red88 N 66.5 327 227 20.4 16.5

lrgalao 1.3 C 75.3 34.6 31.5 225 21.5 Type N 35.2 20.1 11.8 10.9 8.2

Cl Reactive - C99.6 96.5 96.0 93.4 86.4

Red 116 N 98.5 624 60.1 59.4 45.3

Cl Reactive - C 99.8 92.5 91.3 88.1 77.2 Blue 69 N94.3 54.9 53.4 47.6 34.3

C: Competition Dyeing N: Normal Dyeing

Table 3.8. Dye Resist Effects on Modified Wools Chapter3 Preparation and Application of Reactive Resists wools. These data should be of assistance in the interpretation of the dye resist results.

3.3.4. Dye Resist Effects

The results from the dye resist experiments are summarised in Table 3.8. The data has been arranged in the following way:

(i) with the exception of CI Reactive Red 116 and CI Reactive Blue 69, whose structures have not been disclosed, the dyes employed in this study have been listed in descending order of IOR values, and,

(ii) the resist agents have been arranged from left to right in descending order of effectiveness as dye resist agents.

For those dyes that dye wool by ionic/hydrophobic mechanisms, i.e. excluding the reactive dyes, the % dye resist data has been plotted against the IOR values of the dyes for the five dye resist agents (see Figures 3.5-3.9). These graphs show that there is a non-linear relationship between % Resist and IOR values. In competition dyeings resists of greater than 90 % are achieved for dyes having IOR values greater than ea 6.

The results confirm that the dye resist effects achieved with the reactive

81 Chapter 3 Preparation and Application of Reactive Resists

resists are highly dependent on the IOR values of the dyes employed to dye the reactive resist treated wool.

Cl Acid Green 25, which has a relatively low IOR value (3.4) is resisted quite well by the SA, DRB and DRM treated wools (See Table 3.8).

One explanation for this result could be that Cl Acid Green 25 has an anthraquinone chromophore while most of the other dyes employed in this study were azo dyes. Thus molecular structural features may play an important additional role to that of IOR values in determining dye resist effects.

The three additional dyestuffs selected for study (Cl Acid Green 25, Cl Reactive Red 116 and Cl Reactive Blue 69) all exhibit excellent dye resist effects especially to SA, DRB and DRM treated wools.

It is obvious from the data provided in Table 3.8 that SA modified wool gives a superior dye resist (for all eleven dyes examined) to any of the four reactive dye resist agents synthesised in this project. This result is quite explicable when one considers that an 8.5% weight gain for sulphamic acid treated wool represents circa 0.88 mmoVg of sulphamate and/or sulphonate groups in the SA modified wool. This amount far outweighs the 0.32 mmoVg achieved with the DRM modified wool.

Of the four reactive resists synthesised in this project, DRB gives the highest dye resist effect for all eleven dyestuffs examined. This result is

82 Chapter3 Preparation and Application of Reactive Resists particularly interesting when one considers that, whilst DRB achieves the highest weight gain (11.4% ), DRM actually achieves the highest addition of sulphonate groups (0.32 mmoVg) to wool (see Table 3.7). Of course, DRB is a bifunctional reactive resist because it contains two s-triazine reactive groups. Thus there is a higher probability of reaction between DRB and wool as compared with the reaction of DRM and wool. In the case of reactive dyes, this higher degree of reaction will reduce the nucleophilic sites available for the subsequent reaction between the reactive dye and the DRB modified wool resulting in a high reactive dye resist.

An examination of the dye resist data for the Lanasol-type, Cl Reactive Red 116 and Cl Reactive Blue 69 on DRB and DRM modified wools shows that, for both competition and normal dyeings, the difference in the observed dye resist effect is only slight ( circa 1-2%) and hence the explanation must lie elsewhere.

Since DRB has two s-triazine reactive groups it is highly likely that DRB may cross-link the wool. Such a cross-linking action could greatly reduce both the diffusion coefficients of the dyes in the modified wool and the free volume available within the modified fibre to accommodate the dyes.

ORN modified wool has 0.20 mmoVg of added sulphonate groups yet gives a very poor dye resist to all eleven dyes employed in this study.

83 Chapter 3 Preparation and Application of Reactive Resists

Since the total added sulphonate groups for ORB and ORN modified wools are similar, being 0.24 and 0.20 mmoVg, respectively, the bifunctional nature of ORB leading to cross-links in the wool becomes a plausible explanation.

The DRS modified wool contains 0.24 mmoVg of carboxylate groups and exhibits reasonably good dye resist effects to the eleven dyes employed in this study. However, it is obvious from the data presented in Table 3.8 that ORB and ORM treated wools give the best dye resist effects, with ORB treated wool superior. Even so, full white resists (100% resist) were not achieved with any of the four reactive resists synthesised in this project. Sulphamic acid treated wool remains the best dye resisted wool especially to dyes with high IOR values and to reactive dyes.

Although the IOR values can be used as an important tool in the evaluation of the hydrophilic/hydrophobic character of substances, it must be noted that there are limitations and that the molecular configurations or different chromophores may have to be considered. However, for similar chemical structures or the same chromophore, IOR values can be well utilised.

Since the reactive resists ORB and ORM gave the highest weight gains and best dye resists (see Table 3.8 and Figure 3.3), additional experiments were conducted in order to determine the optimum

84 Chapter3 Preparation and Application of Reactive Resists

Resist% 100.------

95

90

85

80

75 ~------___.____ _._ ____.______, 0 5 10 15 20 25 Quantity applied {% wt/Wt) 8 hrs DRM 8 hrs DRB 12 hrs DRM - ----e-- --e- 12 hrs DRB 24 hrs DRM 24 hrs DRB --A-- _._ - Figure 3.11. Dye Resist Effects for Different Curing Times on DRM & DRB Treated Wool {Curing Temp. 80°C using Cl Reactive Red 116) Chapter3 Preparation and Application of Reactive Resists

Resist% 100 ~------~

90

80

70

60 ..__ ___...__ ___....______._ ____.______. 0 5 10 15 20 25 Quantity applied (% wt/wt) 40°C DAM 40°C DAB 60°C DAM 60°C DAB 80°C DAM 80°C DAB - ----..:i-- ~ - - -.A- Figure 3.1 O. Dye Resist Effects for Different Curing Temperatures on DAM & DAB Treated Wool (Curing time 12 hrs using Cl Reactive Red 116) Cbapter3 Preparation and Application of Reactive Resists conditions for pad-batch application.

Since the reactivity of the s-triazine group is quite high, a balance must be found between the desirable reaction of the s-triazine group with nucleophilic sites in the wool and the undesirable hydrolysis reaction. Thus both curing temperature and time were varied in the pad-batch application method Dye resist effectiveness of the modified wool to a Reactive Red 116 was used to assess pad-batch process conditions.

The dye resist results given in Figure 3.10 clearly indicate that a more effective resist is obtained at a higher curing temperature for both DRM and DRB treated wool. Furthermore, the DRB treated wool exhibits a significantly higher percentage resist at all curing temperatures than does the DRM treated wool. This result is in full agreement with the data in Table 3.7.

In a separate study, the curing temperature was maintained at 80° C and the curing time varied (It is preferable to employ as short a curing time as possible from a commercial point of view.) Again, a superior resist was obtained for DRB treated wool as compared to DRM treated wool for all curing times (See Figure 3.11 ). The optimum conditions of application for both DRB and DRM were 80°C for 24 hours.

The main drawback of these reactive dye resist methods is that 20 % wt/wt. must be applied in order to achieve satisfactory tone on tone

85 Chapter3 Preparation and Application of Reactive Resists effects. In practice, usually less than 4 % owf reactive dyestuff dye is applied to fix on the substrate. This 20 % wt/wt amount may be a limitation to widespread application in industrial use. However it seems to be necessary to treat above 20 % in order to modify the wool substrate sufficiently to block the wool's reactive sites and achieve tone on tone effects. This problem may be solved by pretreatment or aftertreatment of the reactive resists using other techniques such as crosslinking fixing agents. This subject could also be further investigated

It must be noted, however, that a dye resist of < 97% can only be used for tone on tone or dark colour illuminated effects in competition dyeing, while a perfect illuminated dye resist treatment requires > 99% resist

3.3.5. Another Example of IOR Values

Cl Food Red 17 has been one of the popular colourants since stain blocking technology was introduced into the carpet industry in the USA [159]. Kool-Aid is sold as a powder to be diluted with water and contains the food dye FD & C Red 40 ( Colour Index name; Cl Food Red 17) [159]. This colourant is used in stain resist tests. The test method will be described in Chapter 4. The investigation of the dye resist propensity of Cl Food Red 17 seems to be necessary prior to a study of the stain blocking effects achieved by these dye resist agents.

86 Chapter3 Preparation and Application of Reactive Resists

NaOS N=N 3

Figure 3.12. Dye Structure of Cl Food Red 17 Chapter3 Preparation and Application of Reactive Resists

The molecular structure of Cl Food Red 17 is given in Figure 3.12 The IOR value of Cl Food Red 17 is 4.5 (Details are calculated in Appendix: ill). It can be predicted that the dye resist effect achieved for Cl Food Red 17 should be similar to that of Cl Acid Red 44 (2 sulphonic groups) for which the IOR value is 4.4.

Colour Index Name Dye Resist Effect (%)

Sulphamic Acid ORB Treated Treated

Cl Food Red 17 89.9 (Normal) 52.3 (Normal) 91.5 (Competition)

Table 3.9. Dye Resist Effect of Cl Food Red 17

In fact, the dye resist effect for Cl Acid Red 44 on sulphamic acid

treated wool is 88.8 % ( Section 223.5.3), while the dye resist effect for Cl Food Red 17 is 89.9 %.

Thus Cl Food Red 17 does not exhibit an "excellent" dye resist effect in the sulphamic acid dye resist process since the % resist value is below 97 %. It has already been shown that, in order to achieve dye resist values greater than 95 %, the dyestuffs must have IOR values greater than ea 5.5 (Section 22.3.5.3). This result is in agreement with that earlier

87 Chapter3 Preparation and Application of Reactive Resists

finding.

Therefore knowledge of IOR values ( or HLB, QSAR values) enables one to make accurate predictions about dye resist effects. These predictions make it possible for one to achieve some degree of control over these dye resist processes. For example, if we can calculate the IOR values from the chemical structures, we can predict the dye resist effects and choose appropriate dyestuffs depending upon the requirements of the dye resist effects.

3.4. Conclusions

Four reactive dye resist agents containing s-triazine based reactive groups were synthesised and characterised.

Low temperature curing can be applied to produce tone on tone effects or dark colour resist treatments in the case of the bifunctional reactive resist (DRB).

The order of the dye resist effects achieved were found to be consistent with the IOR values of the dyes that follow ionic/hydrophobic dyeing mechanisms.

The dye resist effect achieved by the bifunctional reactive resist (DRB)

88 Chapter 3 Preparation and Application of Reactive Resists was superior to the monofunctional reactive resist (DRM). The

explanation for this difference might be that there are crosslinking effects between the bifunctional groups of DRB and the wool substrate. Hence these bifunctional groups play a physical blocking role together with other ionic repulsion forces. This effect could be the basis for future work.

Full white resist effects seem to be difficult to achieve with reactive resists. Reactive resists are not as good as the sulphamic acid resist process. Although for normal dyeing ( not for competition dyeing), full resists were not successfully achieved with the reactive resists synthesised in this project, the author still believes that the concept of a bifunctional group is worthy of further study. If higher levels of fixation and crosslinking effects could be achieved, then the perfect dye resist process may still be feasible.

The drawback of these reactive dye resist methods is that the reactive resist must be applied above 20 % wt/wt in order to achieve satisfactory tone on tone effects. This amount may be a limitation for the process to be applied in widespread industrial use. However, it seems to be inevitable to treat above 20 % in order to sufficiently block the wool's

reactive groups and achieve tone on tone effects. This problem may be solved by pretreatment or aftertreatment of the reactive resists. This subject could also be further investigated.

89 CHAPTER 4. Stain Blocking Effects of Dye Resist Agents

4.1. Introduction

It is obvious that dye resist technology can be applied to stain blocking technology as most stains such as food dyes, are some form of acid dyes. Therefore it was considered worthwhile to apply these reactive resists to wool and to assess their stain blocking effects. The dye resist mechanism was presumed to be similar to the stain resist mechanism.

Generally, accidental staining occurs at room temperature. Therefore, if a dye resist agent is effective to dyeing or printing procedures which occur at high temperature, it is presumed that this agent may also resist stains which usually occur at room temperature, that is under milder conditions than norm.al dyeing procedures.

Acid food colourants, such as Cl Food Red 17 which most severely stains wool carpets at low temperature, is generally used as a stain to assess stain blocking effects.

This chapter describes the stain resist effects to Cl Food Red 17 when reactive dye resist agents are applied to the wool substrate.

4.2. Materials and Methods

90 Chapter 4 Stain Blocking Effects of Dye Resist Agents

4.2.1. Materials

The wool fabric used was a scoured and decatised 2/2 twill, weight 270 g/m2 fabric as described in Section 3.2.1.1. Cl Food Red 17 (Commer­ cial name; Hexacol Allura Red 17P) was supplied by Hodgsons Dye Agencies Ltd. This commercial dye was used without further purification. Citric acid (Analytical grade) was supplied by Ajax Chemicals. Basolan DC was supplied by BASF.

4.2.2. DCCA Treatment [160]

In order to compare the stain blocking effects of untreated wool with those of surface modified wool, wool fabric was chlorinated in a paddle dyeing machine (S. Pegg & Son Textile Engineers PD 2719) at a liquor ratio of 30:1. Wool was treated at 20°C with solutions containing 6 % w/w of Basolan DC (DCCA; Dichiaro isocyanuric acid sodium salt), 10 % w/w sodium chloride and 0.01 % w/w Lissapol 'IN450 (ICI) and adjusted to pH 4.5 with acetic acid The machine was run for 10 minutes and the temperature raised to 30° C and maintained there for 30 minutes. The wool fabric was given an antichlor aftertreatment with sodium bisulphite (3 % w/w) for 30 minutes at 40°C.

4.2.3. Application of Reactive Resists

91 Chapter 4 Stain Blocking Effects of Dye Resist Agents

The reactive resists were applied to wool fabric by the exhaustion method described in Section 3.2.1.9.

4.2.4. Sulphamation of Wool

In order to compare the stain blocking effect with dye resist effects, the wool was sulphamic acid treated as earlier described in Section 2.2.2.1.

4.2.5. Staining Method

Staining was carried out according to the modified method of Harris et al. [161]. Preliminary experiments showed that direct immersion in the staining solution was not suitable for a staining test as the sample was not sufficiently wetted to absorb the stain. Therefore, reactive resist treated samples (1 g) were prewetted in 0.1 % Lissapol TN450 solution for 30 min and then hydroextracted. These samples were then immersed in 200 ml of a solution containing 0.056 g/1 CI Food Red 17 adjusted to pH 2.8 with citric acid and held at room temperature. The samples were removed from the staining bath after 30 min and rinsed thoroughly in running water and then deionised water. The excess moisture was absorbed with paper towel and the samples were dried at 95°C until constant weight was achieved. Sulphamic acid treated wool samples were also stained by the same method.

92 Chapter4 Stain Blocking Effects of Dye Resist Agents

Exhaustion (%) 12 11 10 9 8 7 6 5 4 3 2 1 o...,...... ,,===.;;_____J'--_____;i;'--___._ _ ___.__----'-----'------'-----'------' 0 2 4 6 8 10 Tlme (vt), vmln Untrt3ated ---~--- ~~~ SA 8!!

4.2.6. Determination of Stain Blocking Effects

The extent of staining was quantified as the percentage resist, which is obtained on the basis of the following formula The reflectance values were determined as described in Section 22.25.

SR (%) - (K/S),,,d - (K/S)nt,d x 100 % (K/S),,,d - (K/S),,,114

in which: SR - Stain Resist Percentage K - Absorption Coefficient S = Scattering Coefficient (K/S)u,ud - Ratio of K to S obtained from unmodified and undyed wool (K/S)u,d = Ratio of K to S obtained from unmodified and dyed wool (K/S)m,d = Ratio of K to S obtained from modified and dyed wool

4.3. Results and Discussion

4.3.1. Exhaustion Curves in Stain Resist Test

Figure 4.1 gives the exhaustion curves obtained in the stain resist test.

93 Chapter 4 Stain Blocking Effects of Dye Resist Agents

Reflectance K/S SR(%) (%) (510nm) u,ud 54.43 0.1908 --- Control (u,d) 28.02 0.9245 0

SA 5275 0.2116 97.3

ORB 43.54 0.3661 76.1

ORM 39.54 0.4622 63.0

DRS 36.47 0.5533 50.6

ORN 30.47 0.7933 17.9

DCCA,SA 45.31 0.3301 81.0

DCCA,DRB 15.36 23320 -191.8

DCCA,DRM 13.77 2.6999 -242.0

DCCA,DRS 12.45 3.0783 -293.6

DCCA,DRN 11.98 3.2335 -314.7

DCCA 11.54 3.3904 -336.1

* SA : Sulphamic acid treated u,ud: Unmodified, undyed u,d: Unmodified, dyed DCCA : DCCA pretreated SR : Stain Resist Effect

Table 4.1. Stain Resist Effects after 30 min Staining Test Chapter 4 Stain Blocking Effects of Dye Resist Agents

The data clearly demonstrates the outstanding stain blocking achieved with sulphamic acid treated wool as judged by the very low exhaustion of Cl Food Red 17. Both DRB and DRM treated wool also exhibit good stain blocking effects.

In order to investigate the effects of the surface modification of wool, the wool fabric was firstly DCCA pretreated and then dye resist treated. The results for DCCA pretreated sulphamic acid treated wool and that of DCCA pretreated and DRB or DRM treated wool after the stain test were quite different. The data in Figure 4.1 shows that DCCA pretreated and DRB or DRM treated wool both exhibit stain assist effects, whereas the DCCA pretreated sulphamic acid treated wool still gives an excellent stain blocking effect.

The explanation for this result may be that the dyeing character of sulphamic acid treated wool predominates over that of DCCA treated wool, whereas the dyeing character of DRB or DRM treated wool cannot block the dye assist effect produced by the DCCA treatment of wool.

4.3.2. Stain Blocking Effects

The stain resist effect results for all dye resist agents examined are given in Table 4.1. Sulphamic acid treated wool shows excellent stain blocking

94 Chapter 4 Stain Blocking Effects of Dye Resist Agents effects. The stain blocking effect of the ORB treated wool is significantly better than the ORM treated wool It must be noted, however, that there is slight staining in the case of ORB treated wool and it is only at an 80 % stain resist value ( and above) that the sample exhibits no noticeable visual staining. Therefore the ORB treated wool also needs more improvement of the stain blocking effect.

The reflectance curves of the stain resist treated wool are given in Appendix IV, Figures A4.1 to A4.4. These curves also confirm the stain resist effects on sulphamic acid treated wool and ORB treated wool.

Whilst the DRS and ORN treated wools give some degree of stain resist (50.6% and 17.9%, respectively), these compounds are not good enough for commercial application.

The effect of the DCCA pretreatment of the wool is quite dramatic. The DCCA acid chlorination treatment partially removes the cuticle of the wool and increases the ease with which the wool can be dyed The DCCA-SA treated wool still exhibits a reasonable stain resist to Cl Food Red 17 with an SR% of 81.0%. Thus it would appear that the sulphamic acid treatment is capable of off-setting most of the dyeing assist effects caused by the DCCA pretreatment.

When applied to DCCA pretreated wool, all four reactive resists synthesised in this project exhibit stain assist effects ( see Table 4.1 ).

95 Chapter 4 Stain Blocking Effects of Dye Resist Agents

Thus the staining ( dyeing) assist effect caused by the DCCA pretreatment (-336.1 % ) swamps the stain resist effects observed with the DR-compounds on untreated wool.

4.4. Conclusions

All five stain resist treatments examined in this project confer some degree of stain blocking onto the modified wool. The order of effectiveness is SA > ORB > ORM > DRS > ORN. However, when applied to DCCA pretreated wool, only the sulphamic acid treated wool exhibited a stain resist effect. All four reactive resists synthesised in this project show a dye assist effect on DCCA pretreated wool. Obviously none of these four resist agents is capable of overcoming the dye assist effect conferred on wool by the DCCA treatment.

Sulphamic acid treated wool shows excellent stain blocking effects. The stain blocking effect of the ORB treated wool is significantly better than the ORM treated wool. It must be noted however, that there is slight staining in the case of ORB treated wool and it is only at 80 % stain resist value ( and above) that the sample exhibits no noticeable visual staining. Therefore the ORB treated wool also needs more improvement in stain blocking effects.

96 CHAPTER 5. CONCLUSIONS

The aim of this project was to develop new and improved methods for the preparation, application and curing of dye resist agents on wool to achieve dye resist effects at low temperature and to elucidate the mechanisms of the dye resist effect.

The sulphamic acid resist process is currently the most successful dye resist process for wool, however, the commercial viability of the process is limited by the very high temperature required for curing. Therefore a study of the dye resist effects achieved with sulphamic acid treated wool were carried out.

The best dye resist effect for the dyes examined is achieved on sulphamic acid treated wool cured at circa 1500C Below this temperature, a dye assist effect is exhibited for reactive and metal complex dyestuffs due to the characteristics of sulphamic acid itself. Dye resist effects depend upon the dyestuffs themselves.

These findings indicate that, for curing temperatures of less than 1400C, unbound sulphamic acid is desorbed from the wool during dyeing with a consequent lowering of dyebath pH.

The dye resist effect is highly dependent on the hydrophilic/hydrophobic character of the dyestuffs and substrate. With the exception of reactive

97 Chapter 5 Conclusions dyes, this work shows that the IOR values of the dyes should be greater than 5.5 in order to achieve dye resist values of better than 95% on sulphamic acid treated wool.

IOR values can be used as an important tool in the evaluation of the hydrophilic/hydrophobic character of dyes. This technique should be of great value in the understanding dye resist processes.

Four reactive dye resist agents were synthesised and characterised. The orders of dye resist effects observed are consistent with the IOR values of the dyes which dye wool by ionic/hydrophobic dyeing mechanisms.

The results indicate that low temperature curing of the reactive resists can be applied to produce tone on tone effects or dark colour resist treatments in the case of the bifunctional reactive resist The optimum conditions for pad-batch application were found to be 80° C for 24 hours.

The dye resist effects of bifunctional groups are superior to those of monofunctional groups, especially in competition dyeing. The causes of these effects might be that there are crosslinking effects between bifunctional groups and the wool substrate, and these bifunctional groups play a shielding role together with other repulsion forces.

Sulphamic acid treated wool shows excellent stain blocking effects. The stain blocking effect of the ORB treated wool is significantly better than

98 Chapter S Conclusions the ORM treated wool. It must be noted however, that there is slight staining in the case of ORB treated wool and it is only at 80 % stain resist value ( and above) that the sample exhibits no noticeable visual staining. Therefore ORB treated wool also needs more improvement of the stain blocking effect.

Full white resists effects seem to be difficult for reactive resists to achieve. The sulphamic acid resist process remains the best process. Although for normal dyeing, (not for competition dyeing,) the reactive resists synthesised in this project were not highly successful, the author still believes that the concept of a bifunctional group is worthy of further study. If higher levels of fixation and crosslinking effects could be achieved at the same time, the "perfect" dye resist process may still be feasible.

Although time constraints did not permit the additional study of the bifunctional group and crosslinking effects on dye resist processes, there is much scope for future work in this area.

99 Bibliography

BIBUOGRAPHY

1. Knecht, E. and Fothergill J. B., The Principles and Practice of Textile Printing, Charles Griffin & Company Limited, 4th Ed., London, 1952, 581.

2. Berry, C. and Ferguson, J. F., Discharge, Resist and Special Styles, in Miles, L W. C., Textile Printing, Dyers Company Publication Trust, Bradford, England, 1981, 195.

3. Wurtz, V., Resist and Discharge Printing on Cellulosic Fibres, Melliand Textilber., 62, 1981, 883.

4. Maclaren, J. A and Milligan, B., Wool Science: The Chemical Reactivity of the Wool Fibre, Science Press, Marrickville N.S. W., 1981, 308.

5. Bird, C. L, The Theory and Practice of Wool Dyeing, The Society of Dyers and Colourists, 1972, 167.

6. Brady, P.R., The Printing of Wool Fabrics, Text. Prog., 12, No.3, 1982, 3.

7. Sandoz, Bazel, Switzerland, USP. 2,726,133, 6 Dec. 1955.

8. Bell, V. A, Lewis, D. M and Pailthorpe, M. T., Chemical Treatments Designed to Modify the Affinity of Wool for Dyes, J. Soc. Dyers Col, 100, 1984, 223.

9. Harper, H. A, Review ofPhysiological Chemistry, Lange Medical Publication, 10 Ed., California, 1965.

10. Simmonds, D. H., Variations in the Amino Acid Composition of Merino Wool, Proc. Int. Wool Text. Res. Conf., Australia, C, 1955, 65.

11. Mark, H. F., Gaylord, N. G. and Bikales, N. M., Encyclopedia of Polymer Science and Technology, Vol 1, John Wiley & Sons, Inc., New York, 1964, 878.

100 Bibliography

12. Asquith, R. S., Chemistry of Natural Protein Fibres, Plenum Press, New York, 1977, 193.

13. Leon, N. H., The Chemical Reactivity and Modification of Keratin Fibres, Text. Prog., 7, 1975, 1.

14. Maclaren, J. A, Savige, W. E. and Sweetman, B. J., Disulphide Monoxide Groups in Oxidised Proteins,Aust. J. Chem., 18, 1965, 1655.

15. Thompson, E. 0. P. and O'Donnell, I. J., Studies on Oxidised Wool, Aust. J. Biol ScL, 12, 1959, 282

16. Maclaren, J. A and Sweetman, B. J., The Preparation of Reduced and s-Alkylated Wool Keratins Using Tri-n-Butyl Phosphine, Aust. J. Chem., 19, 1966, 2355. Sweetman, B. J. and Maclaren, J. A, The Reduction of Wool Keratin by Tertiary Phosphines, Ibid, 19, 1966, 2347.

17. Wolfram, L J., The Reaction of Tris-Hydroxy Methyl-Phosphine with Keratin, Proc. Int. Wool Text. Res. Conf.(CIRTEL), Paris, II, 1965, 505.

18. Middlebrook, W. R. and Phillips, H., The Action of Sulphites on the Cystine Disulphide Linkages of Wool. The Subdivision of the Combined Cystine into Four Fractions Differing in Their Reactivity towards Sodium Bisulphite, Biochem. J., 36, 1942, 428.

19. Gillespie, J. M., Reaction of Sodium Borohydride with Wool, Nature, 183, 1959, 322.

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112 Appendices

APPENDIX I. Calculation of IOR Values[141]

1. Quantity of Organic Character

The methylene group is taken as the unit and is measured by the number of carbon atoms that represent the group. One carbon atom is taken as 20.

2. Quantity of Inorganic Character

The hydroxyl group is taken as the standard. In order to make the comparison with organic character easier, the influence of one hydroxyl is taken as 100. The quantity for the influence of other substituents is calculated by the comparison of a distance between the curve of the methane series hydrocarbons and the curve of any optional substituted homologues with the distance of the hydrocarbons and alcohol curves.

IOR - BIO so

where SIO Sum of Inorganic Character of Substituents SO Sum of Organic Character of Substituents

113 Appendices

3. Table of IOR Values of Substituents

SUBSTITUENT INORGANIC CHARACTER

Light metal 500

Heavy metal 400

-AsO;H27-AsO2H 300

-SO2-NH-CO-, -N=N-NH2 260

=N-OH, -SO;H, -NH-SO2-NH- 250

-CO-NH-CO-NH-CO- 250

=SOB, -CO-NH-CO-NH- 240

-SO2-NH- 240

-CS-NH-, -CO-NH-CO- 230

=N-OH, -NH-CO-NH- 220

=N-NH-, -CO-NH-NH- 210

-CO-NH- 200

-COOH 150

Lactone 120

-CO-O-CO- 110

114 Appendices

SUBSTITUENT INORGANIC CHARACfER

Antbracene, Phenanth.rene(Nucleus) 105

-OH 100

>Hg 95

-NH-NH-, -0-CO-O- 80

-N< (Amine character) 70

>CO 65

-COOR 60

Naphthalene, 60 Quinoline (Nucleus)

>C=NH 50

-N=N- 30

-0- 20

Benzene (Nucleus) 15

Nucleus 10

Triple bond 3

Double bond 2

115 Appendices

SUBSTITUENT ORGANIC INORGANIC CHARACTER CHARACTER

R.BiOH 80 250

R,.SbOH 60 250

R..AsOH 40 250

RJ>OH 20 250

>SO2 40 110

-CSSH 120 80

-S-CN 90 80

-CSOH, -COSH 80 80

-NCS 70 75

-NO2 80 70

-Bi< 60 70

-Sb< 60 70

-As<, -CN 40 70

-P< 20 70

-CSSR 130 50

116 Appendices

SUBSTITUENT ORGANIC INORGANIC CHARACTER CHARACTER

-CSOR, -COSR 80 so

-NO so so

-O-N02 60 40

-NC 40 40

-Sb=Sb- 90 30

-As=As- 60 30

-P=P-, -NCO 30 30

-0-NO, -SB, >S 40 25

=S so 10

-I 80 10

-Br 60 10

-Cl 40 10

-F 5 5 lso >- -10 0

Tert. >- -20 0

117 Appendices

3. Examples of Calculation of IOR Values

Cl Acid Red 88

Organicity : C 20x 20 - 400 lnorganicity : -OH 100 X 1 - 100 -N=N- 30 X 1 - 30 -SOJI 250x 1 - 250 -Na 500 X 1 - 500 Naphthalene 60 x2 - 120

------1000

IOR = S10/SO = 1000 / 400 = 2.5

Cl Acid Red 44

Organicity : C 20x 20 - 400 Inorganicity : -OH lOOx 1 - 100 -N=N- 30x 1 - 30 -SOJI 250x2 - 500 -Na 500x 2 - 1000 Naphthalene 60x 2 - 120

118 Appendices

------·------1750

IOR = S1O/SO = 1750 / 400 = 4.4

Cl Acid Red 27

Organicity : C 20x 20 - 400

Inorganicity : -OH 100 X 1 - 100 -N=N- 30x 1 - 30 -SOJI 250x3 - 750 -Na 500x 3 - 1500 Naphthalene 60x 2 - 120

2500

IOR = S1O/SO = 2500 / 400 = 6.3

Cl Acid Red 41

Organicity : C 20x 20 - 400

Inorganicity : -OH 100 X 1 - 100 -N=N- 30 X 1 - 30 -SOJI 250x4 - 1000 -Na 500 X 4 - 2000

119 Appendices

Naphthalene 60 x 2 = 120 ------3250 IOR = S1O/SO = 3250 / 400 = 8.1

Cl Acid Red 1

Organicity : C 18 X 20 - 360 lnorganicity : -OH 100 X 1 = 100

-N=N- 30 X 1 - 30 -SOJI 250x 2 = 500 -Na 500x 2 - 1000 -NHCO 200x 1 = 200

Benzene 15 X 1 - 15

Naphthalene 60 X 1 - 60

1905 IOR = S1O/SO = 1905 / 360 = 5.3

Cl Acid Red 138

Organicity : C 30 X 20 600

Inorganicity : -OH 100 X 1 100

120 Appendices

-N=N- 30 X 1 - 30 -SO:J{ 250x 2 - 500 -Na 500x 2 - 1000 -NHCO 200x 1 - 200 Benzene 15 X 1 - 15 Naphthalene 60x 1 - 60 ------1905

IOR = S10/SO = 1905 / 600 = 3.2

Lanasol Type

Organicity : C 20x 29 580 -Br 60x 2 120 ---·------700

Inorganicity : Benzene 15 X 12 - 180 Naphthalene 60x 1 - 60 -OH 100 X 1 - 100 -NHCO 200x 3 - 600 -Br lOx 2 - 20

-N=N- 30 X 1 - 30 -SO:J{ 250x2 - 500

121 Appendices

-Na 500x 2 1000

-C=C -2 X 2 4

------,______,__ _ 2494

IOR = S1O/SO = 2494 / 700 = 3.6

lrgalan Type

Organicity : C 20x 36 - 720 Inorganicity : -0- 20x 4 - 80 -N=N- 30x 2 - 60 -NHR 70x 2 - 140 -COOR 60x 2 - 120

Benzene 15 X 2 - 30 Naphthalene 60x 2 - 120 Heavy Metal 400x 1 - 400

------950 IOR = S1O/SO = 950 / 720 = 1.3

122 Appendices

APPENDIX II. IR Spectra of Reactive Resists

g z .~ 0' !:

I "' ~.. 2 0... I 0 :c CL 0 "'... '! ...u ' CL "' ' 0 ..ac I C "'... . ----~-- !: = I

~ ! I 0 ..N .., ..0 0 I 2 - • 2· <.) --~ ------4 la: ======.-=.-=-=--~-::===~;;::::=::::::::::--~- ~-=_=_:_:_ =_ =_ =_ =_ =_ =_ ~-·~ l > . ------l !"i.

123 Appendices

i C: -----·--"' - ! ------;::-._------!.:.:...------;:;::,.-==-=;;:------""'.'"".:-:----

~~--~-~~~~~~~~=-=-=~~~~~-~ --- ::~-~=-~~:~-;~---:·.==~--=----= ___ :.: ____ -~-~ -=: __

2 cC :... 0 ..0: _, ...u "' ...Cl 0: I C • "'... ! I

Cl I I ..0 .....N I i . I a lis I ~

-••--::::====~-.....::,-~------··- • ,. ---- ·--- c- - cf•: II ~ i i

124 Appendices

"'a:. ::E· ... C ; "'' -----· ------.. :_...,,_ I

-~ -- : =-,:..= I

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~ ~ Appendices

APPENDIX m. IOR Values of Cl Food Red 17 and Cl Acid Green 25

1. Cl Food Red 17

Organicity : C 18x 20 360

Inorganicity : -N=N- 1 X 30 - 30

-0- 1 X 20 - 20 -SOJi 2x 250 - 250 -Na lx500 - 500 Naphthalene 1 X 60 - 60 ------1625

IOR = S1O/SO = 1625 / 360 = 4.5

2. Cl Acid Green 25

Organicity : C 28x 20 560

Inorganicity : Amino 2x 70 140 -C=O 2x 65 130

127 Appendices

-SO:/{ 2 X 250 - 250 -Na lx500 - 500

Benzene 2 X 15 - 30 Anthracene 1 x 105 - 105

------1905

IOR = S10/S0 = 1905 / 560 = 3.4

128 Appendices

APPENDIX IV. The Reflectance Curves of the SR treated Wool

_:: I

T

i_:j -. .;.. .-. .---

..., .- ;..: L'ai ·=-,:, ai Q E E E :l. C: C: C ·~ .:, Q ·-·,-. .-. ·-·

* Treated: Control:

Figure A4.1. Reflectance Curve of SA treated Wool

129 Appendices

;-!

____-.....~~------___ :--= - :::: ---~--~ = ,"T"

- .L..---

E 'e E E " C C C .__, C, ,-, If)

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• Treated:

Control:

Figure A4.2. Reflectance Curve of DRB treated Wool

130 Appendices

.. :..;_

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L cr.; ,-, e E E E E '1. ,: C r: C r: ,5 -0

* Treated: Control:

Figure A4.3. Reftectance Curve of DCCA-SA treated Wool

131 Appendices

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• Treated: Control:

Figure A4.4. Reflectance Curve of DCCA-DRB treated Wool

132