Dyeability of Cationised Cotton and Nylon 6 Fabrics Using Acid Dyes

Indian Journal of Fibre & Textile Research Vol. 36, March 2011, pp. 88-95

Dyeability of cationised cotton and nylon 6 fabrics using acid dyes

M M El-Molla a Textile Research Division, National Research Centre, Dokki, Cairo, Egypt and N A Badawy, A Y AbdEl-Aal, A A El-Bayaa & H M G El-Shaimaa Faculty of Science (Girls), Al-Azhar University, El-Nasser City, Cairo, Egypt

Received 13 January 2010; revised received and accepted 5 May 2010

Cationisation of cotton and nylon 6 fabrics has been done using Solfix E, Tino fix ECO, Acramine berfix K and cetyl trimethyl ammonium bromide to impart cationic sites on fabric surface for improving their substantivity to acid dyes. Pre- cationisation of cotton and nylon 6 fabrics improves the depth of the colour as well as fastness properties. In all the cases, the overall colour fastness of cationic cotton dyed with acid dyes is found to be comparable to the colour fastness of the nylon 6 dyed with same acid dyes .

Keywords: Acid Dyes, Cationisation , Cotton, Dyeability, Nylon 6

1 Introduction functionality and reactivity of the cationic agents have Producing cotton fabrics with improved dyeing also been compared. properties has been studied by many researchers 1. Recently, the chemical modification of cellulosic 2 Materials and Methods fibres to enhance dyeability has been reviewed 2.1 Materials 2 comprehensively by Lewis and Mcllroy and 2.1.1 Fabric Renfrew 3. The purpose of the cationisation of cotton The grey cotton fabric of about 140 g/m 2 (supplied is to increase the neutral substantivity of anionic dyes by the Misr Helwan Company) was bleached by a for cotton by introducing positively charged sites on combined scouring and bleaching method with the the cotton. Pretreatments of cotton using compounds, bath liquor containing 0.75% of the wetting agent such as glycidyltrimethyl-ammonium chloride and Sandozin NIE, 4.0% hydrogen peroxide and 2.5% polyamide epichlorohydrin resin with and without sodium hydroxide at pH 10.5, liquor ratio 1:10, thiourea or ethylenediamine to increase the dyeability temperature 90 °C and treatment time 90 min. 4-6 for anionic dyes have already been reported . In 2 Nylon 6 fabric of about 200 g/m (supplied by addition, the dyeability of cotton grafted with El-Nasr Company) was treated with a solution acrylonitrile and vinyl pyridine has also been containing 2 g/L detergent and 2 g/L sodium studied 7,8 . Nylon fabric was dyed with a disperse- carbonate at 80 °C for 1 h, then thoroughly washed reactive yellow dyestuff using a supercritical carbon ° dioxide dyeing process 9. and air dried at room temperature (25 C) . The present study was aimed at investigating the dyeing behaviour of typical commercial anionic dyes 2.1.2 Dyestuffs on cotton and nylon 6 fabrics after cationisation with Amainyl Cyanine M5R (133%) (C.I. Acid Blue different reactive cationic agents, such as Solfix E, 113) and Ambllan Yellow GR (C.I. Acid Yellow 99), CIBA tino fix ECO, Acramine berfix K and cetyl both procured from ICI, England, were used (Fig. 1). trimethyl ammonium bromide (CTMAB). The 2.1.3 Chemicals ______Solfix E— polyamino chlorohydrin quaternary aTo whom all the correspondence should be addressed. ammonium polymer with epoxide reactivity E-mail: [email protected] (CIBA Gigy Co., Switzerland) , Tino fix ECO EL-MOLLA et al .: DYEABILITY OF CATIONISED COTTON AND NYLON 6 FABRICS USING ACID DYES 89

2.3 Measurement and Analysis The whiteness index (WI), expressed as CIE units, was measured for cationised fabrics as per AATCC standard test method 12 using international data colour. Tensile strength and elongation-at-break were determined according to ASTM standard test method 13 . The nitrogen contents of the cationised fabrics were determined by the cole and parks modification of the micro Kjeldahl method 14 . Color strength ( K/S) was measured according to a previously reported method 15 by the light reflectance technique, and the relative color strength was

calculated by applying the following Kubelka-Munk Fig. 1—Structure of (a) Amainyl Cyanine M5R and (b) Ambllan Yellow GR equation: (1−R )2 (1 − R ° ) 2 (CIBA Gigy Co., Switzerland), Acramine berfix K Color strength ( K/S) = − …(1) 2R 2 R ° (Payer Company), cetyl trimethyl ammonium bromide, sodium hydroxide, sodium carbonate, acetic where R and R° are the decimal fraction of the acid. Univaden PA (leveling agent) and urea, all of reflectance of the colored and uncolored fabrics laboratory grade, were used. respectively; K, the absorption coefficient; and S, the scattering coefficient. 2.2 Methods Fastness to washing, rubbing and perspiration were 2.2.1 Cationisation Procedure measured according to a standard methods 16 . The cationic reagent of the conc. 50, 100 and 150 g/L with corresponding sodium hydroxide conc. 3 Results and Discussion of 31.0, 62.0 and 93.0 g/L respectively were used. 3.1 Effect of Cationic Concentrations on Nitrogen Content Cationisation 10 was carried out using two different Cationisation of cotton was done using Solfix E, techniques, namely pad-batch method 11 and Tino fix ECO, Acramine berfix K and CTMAB to exhaustion method. impart cationic sites on cotton fabric surface to improve its substantivity to anionic dyes. The cationic The fabric was immersed in the cationisation bath, reagents react with cotton in the presence of alkali by ° having a goods-to-liquor ratio of 1:20 for 1 h at 50 C. forming ether linkages with cellulosic fibres, the After that, the different concentrations of NaOH were resultant is a cationised cotton fabric carrying positive added and the reaction was continued for another 2 h. charges. The effect of cationic reagent concentrations Finally, the samples were rinsed with water, on the nitrogen content of the cationised cotton fabric naturalized with 2 g/L acetic acid, again rinsed with is shown in Table 1. It is clear that as the cationic cold water and then air dried. reagents concentration increases the nitrogen content of the cotton fabric also increases, irrespective of the 2.2.2 Dyeing Procedure reagent used and the technique applied. Both without cationised (untreated) and cationised Some properties of the treated and untreated fabrics (treated) fabrics were dyed with 2% (owf) dye, 1 g/L are also shown in Table 1. It can be observed that the acetic acid and 1 g/L Univaden PA, maintaining cationisation process produces some loss in whiteness material-to-liquor ratio at 1 : 20. of the fabric. This is a general characteristic result of The temperature was slowly raised to 98 °C and the cationisation process. dyeing was continued further for 1 h. The samples The whiteness index (WI) decreases from 61 for were taken out, rinsed with hot water at 60 °C for the untreated cotton to 49.6, 54.7, 47.6 and 57.8 for 15 min, followed by rinsing with cold water and then the fabrics treated with Solfix E, Tino fix ECO., air dried. Finally, these samples were dried and Acramine berfix K and CTMAB respectively. This assessed for colour strength and overall fastness loss in whiteness due to cationic treatment is properties. considered to be acceptable when compared to 90 INDIAN J. FIBRE TEXT. RES., MARCH 2011

Table 1 — Effect of cationisation on cotton fabric properties

Cationic Reagent Pad-batch method Exhaustion method reagent conc. Nitrogen Whiteness Tensile Elongation Nitrogen Whiteness Tensile Elongation g/L content index strength % content index strength % %N kg.f %N kg.f

Control - 0.04 61.0 50.0 35 0.04 61.0 50.0 35.0

Solfix E 50 0.44 54.4 41.5 23 0.57 42.1 41.5 23.0 100 0.63 52.0 47.5 25 0.79 34.7 47.5 24.0 150 1.34 49.6 53.0 27 1.45 32.7 53.0 26.0

CIBA 50 0.42 57.9 49.0 23 0.55 56.9 55.0 19.0 tino fix 100 0.61 55.8 53.5 24 0.69 54.6 55.5 20.5 ECO 150 0.65 54.7 56.0 26 0.74 53.4 56.5 22.0

Acramine 50 0.29 50.7 51.0 30 0.43 47.9 53.0 26.0 berfix K 100 0.38 48.5 55.5 31 0.59 45.3 57.0 27.0 150 0.62 47.6 58.0 32 0.82 44.2 60.5 28.0

CTMAB 50 0.17 55.7 38.5 25 0.23 57.4 42.0 23.0 100 0.28 57.5 42.5 26 0.32 57.7 38.0 24.0 150 0.38 57.8 45.5 27 0.45 57.9 35.0 25.0

Table 2 — Effect of cationisation on the nylon 6 fabrics properties

Control – 0.20 39.0 55.0 155 2.20 39.0 55.0 155

Solfix E 50 0.69 31.6 50.5 132 0.78 32.4 44.0 102 100 0.84 20.9 37.5 140 1.02 27.2 33.5 123 150 1.44 13.5 29.0 143 1.53 21.4 30.5 134

Acramine 50 0.30 33.7 50.5 120 0.32 33.8 46.0 109 berfix K 100 0.36 29.9 46.5 125 0.48 32.2 40.5 120 150 0.49 27.7 40.5 130 0.52 30.4 38.0 145

CTMAB 50 0.23 29.9 50.0 96 0.27 28.6 46.0 114 100 0.25 37.6 43.5 110 0.33 31.4 39.0 126 150 0.26 38.2 26.0 122 0.42 33.0 27.0 139

whiteness results of 53.5 obtained with some other 3.2 Dyeing Analysis of Cationised Cotton and Nylon 6 Fabrics cationic reagents. This could be attributed to the Cationic cotton, chemically modified with Solfix E, presence of nitrogen in cationic reagent used. Also, it Tino fix ECO, Acramine berfix K and CTMAB can be observed from the results that cationisation containing quaternary groups, has been thoroughly process also produces some loss in tensile strength of investigated for its dyeability. Most acid dyes are the fabric. known to have very little affinity for cotton The effect of cationic reagent concentrations on the (untreated). However, after cationisation the cotton nitrogen content of the cationised nylon 6 fabric is can be dyed readily with acid dyes. shown in Table 2. It is observed that as the cationic The sulphonic acid groups present in the dye reagents concentration increases the nitrogen content molecules can interact with the cationic groups in the of the nylon 6 fabric also increases, irrespective of the modified cotton. The aim of this study was to dye reagent used and the technique applied. The effect of cationized cotton with conventional acid dyes cationic agent concentration on the properties of (C.I. Acid Blue 113 and C.I. Acid Yellow 99) and to nylon 6 fabric is shown in this table. It is observed study their fastness properties . Untreated cotton does that the cationisation process produces some loss in not normally give useful shade depths with acid dyes, whiteness and tensile strength of the fabric. due to the lack of affinity between the fibre and the EL-MOLLA et al .: DYEABILITY OF CATIONISED COTTON AND NYLON 6 FABRICS USING ACID DYES 91

anionic acid dye molecules. This lack of affinity is The colour yield and exhaustion of cationised due to the relatively nonlinear molecular structures of cotton improve with increasing conc. (50, 100 and acid dyes, which, in turn, prevents hydrogen bonding. 150 g/L) of cationic agents Solfix E, Tino fix ECO, For dyes with linear structure, significant hydrogen Acramine berfix K, and CTMAB. The K/S of bonding is evident between the dye molecule and the cationized cotton is found to be higher than that of the cellulose hydroxyl groups. Acid dyes are therefore untreated cotton [Figs 2(a)-(d)]. Figure 2(a) shows used to dye nylon. However, cotton modified with that the K/S values of C.I. Acid blue 113 (2% owf) cationic dye sites will strongly attract acid dyes, dyed cotton increase from 1.4 for untreated sample to allowing such cotton to be dyed in good colour yields 21, 20, 15.5 and 11.7 after cationisation with 150 g/L with typical acid dyes. Solfx E, Tino fix ECO, Acramine berfix K and Acid dyes are only applied to fibres with positive CTMAB respectively using pad-batch method. charges, such as polyamide fibres in an acidic bath. However, the fact that cationic cotton can also be The nitrogen content of C.I. Acid Yellow 99 effectively dyed with acid dyes using both application (2% owf) dyed cotton untreated and treated with methods is shown in Fig. 2. 150 g/L Solfix E, Tino fix ECO, Acramine berfix K and CTMAB is found to be 0.04 (~ zero), 1.34, 0.65, 0.62 and 0.38 respectively.

In the case of modified cotton, for different cationic agents the colour strength after washing and nitrogen content decrease in the following order:

Solfix E > Tino fix ECO > Acramine berfix K > CTMAB

This behaviour is attributed to the forces of attraction between cationic sites in the cationised cotton and anionic sulphonic acid groups present in the structure of dyestuff, which make the dye more resistant to extraction with this reagent. The higher the concentration of the dye, the more molecules are available to aggregate in the dye solution which leads to greater colour strength. Figures 2(c) and (d) also show progressive increase in colour strength of the cationised cotton in case of exhaustion method. It is therefore advisable to carry out dyeing of the modified cotton fabrics at 98 °C. Increasing the temperature allows swelling of the amorphous region in the cotton, which leads to a higher colour strength. The extent of reaction between the cationic agents and the cotton was also assessed by determining the extent of dyeing exhaustion and fixation on pre- treated cotton fabrics [Figs 2(a)-(d)]. It is clear that the dyed fabric pre-treated with Solfix E has higher colour strength and exhaustion values than the corresponding fabric treated with Tino fix ECO,

Acramine berfix K and CTMAB. This appears to be Fig. 2—Effect of cationic agents concentration on colour strength reasonable as Solfix E, having one quaternary of cationised cotton fabric by using 2% (owf) acid dyes [(a) Acid ammonium cations and epoxide, creates more fixed Blue 113, pad-batch method; (b) Acid Yellow 99, pad-batch method; (c) Acid Blue 113, exhaustion method; and (d) Acid cationic dye sites, which results in higher uptake and Yellow 99, exhaustion method dye-fibre fixation percentage. 92 INDIAN J. FIBRE TEXT. RES., MARCH 2011

The K/S curves highlight differences between the dyed with acid, disperse and metal complex dyes, but dyed nylon 6 and cationic cotton fabrics. The C.I. their mechanisms of fixation are theoretically Acid Blue 113 dyed cationic cotton shows darker different. In polyamide dyeing however, these dyes shades than nylon 6 (Fig. 3). seem to be adsorbed onto particular sites 17 . Acid dyes The exhausted dyebath from the cationic cotton- classically follow a saline bond mechanism, but their acid dye system had significantly less colour affinity and the irreversibility of fixation are due to remaining than the exhausted dye bath from the hydrophobic interactions. Moreover, one part of the nylon-acid dye system. dye is not fixed by a saline bond (i.e. presence of Figure 3 shows that the colour strength increases positive & negative charge attraction) but by with the increase in cationic agents concentration. adsorption onto polar sites. The dyeing of nylon 6 However, in the case of untreated cotton, the colour fibres is nowadays essentially carried out using acid strength is found to be very low because acid dyes dyes. However, although these dyestuffs do offer an have very low affinity for cotton. Polyamide can be extensive colour range and bright shades, they do

Fig. 3—Spectral curves showing uptake of C.I. Acid Blue 113 on cotton and nylon 6 fabrics untreated and treated with Solfix E using pad-batch method EL-MOLLA et al .: DYEABILITY OF CATIONISED COTTON AND NYLON 6 FABRICS USING ACID DYES 93

have some disadvantages, including the fact that dyeing with acid dyes can exhibit non- uniformity, particularly if good wet fastness is obtained. Figures 4(a)-(d) show the effect of cationising agents conc. on colour strength of nylon 6 fabrics and the results show a marginal difference due to the difference in fabric composition as compared to cotton fabrics.

3.3 Effect of Dyestuff Structure The colour strength of C.I. Acid Blue 113 is found to be better than that of C.I. Acid Yellow 99 (Figs 2 and 4). Data for the untreated fabric are not given since there is little affinity between the dye and the cotton. Nevertheless, as previously mentioned, the dyestuff structure and the cationised cotton structure play a considerable role in the electrostatic attraction between the two dyes. For C.I. Acid Yellow 99, the hydrogen bonding between nucleophilic groups in the dye molecule and hydroxyl groups in cotton reinforces the electrostatic attraction between the anionic dye and the cationic sites. Hence, C.I. Acid Blue 113 due to two sulpho groups shows markedly higher colour strength than C.I. Acid Yellow 99. The latter dye has only one sulpho group but differs in the nature of the nucleophilic group present.

3.4 Color Fastness Analysis The color fastness results for both the dyes on cationic cotton are given in Tables 3 and 4. Increasing the number of cationic dye sites in the cationic cotton may provide more acceptable wash fastness in the cationic cotton-acid dye system.

Generally, the values of the colour fastness to Fig. 4—Effect of cationic agents concentration on colour strength of rubbing and perspiration change from very good to cationised nylon 6 by using (2% owf) acid dyes [(a) Acid Blue 113, pad-batch method; (b) Acid Yellow 99, pad-batch method; (c) Acid excellent in both the cases, i.e. wet or dry rubbing, Blue 113, exhaustion method; and (d) Acid Yellow 99, exhaustion and acidic or alkaline perspiration. method

Table 3 — Fastness properties of untreated and treated cotton dyed with 2% (owf) C.I. Acid Blue 113 using exhaustion method

Cationic Reagent Rub fastness Wash fastness Perspiration fastness reagent conc., g/L Wet Dry St. Alt Acidic Alkaline St. Alt. St. Alt.

Control - 4 4 4 4 4 4 4 4

Solfix E 50 4-5 5 5 5 5 5 5 5 100 4-5 5 5 5 5 5 5 5 150 4-5 5 5 5 5 5 5 5

CIBA tino fix 50 4 4-5 4-5 4-5 4 4 4 4 ECO 100 4 4-5 4-5 4-5 4 4 4 4 150 4 4-5 4-5 4-5 4-5 4-5 4-5 4-5 —Contd

94 INDIAN J. FIBRE TEXT. RES., MARCH 2011

Table 3 — Fastness properties of untreated and treated cotton dyed with 2% (owf) C.I. Acid Blue 113 using exhaustion method — Contd

Cationic Reagent Rub fastness Wash fastness Perspiration fastness reagent conc., g/L Wet Dry St. Alt Acidic Alkaline St. Alt. St. Alt.

Acramine 50 4 4-5 4 4 4 4 4 4 berfix K 100 4 4-5 4 4 4 4 4 4 150 4 4-5 4 4 4 4 4 4

CTMAB 50 4 4-5 4-5 4-5 4 4 4 4 100 4 4-5 4-5 4-5 4-5 4-5 4-5 4-5 150 4 4-5 4-5 4-5 4-5 4-5 4-5 4-5

Table 4 — Fastness properties of untreated and treated cotton dyed with 2% (owf) C.I. Acid Yellow 99 using exhaustion method

Cationic Reagent Rub fastness Wash fastness Perspiration fastness reagent conc., g/L Wet Dry St. Alt Acidic Alkaline St. Alt. St. Alt.

Control - 4 4 4 4 4 4 4 4

Solfix E 50 5 5 5 5 5 5 5 5 100 5 5 5 5 5 5 5 5 150 5 5 5 5 5 5 5 5

CIBA tino fix 50 4-5 5 5 5 5 5 5 5 ECO 100 4-5 5 5 5 5 5 5 5 150 4-5 5 5 5 5 5 5 5

Acramine 50 4-5 4 4-5 4-5 4-5 4-5 4-5 4-5 berfix K 100 4-5 4 5 5 4-5 4-5 4-5 4-5 150 4-5 4-5 5 5 5 5 5 5

CTMAB 50 4-5 5 4 4 3-4 3-4 3-4 3-4 100 5 5 4 4 4 4 4 4 150 5 5 4 4 4 4 4 4

Table 5 — Fastness properties of untreated and treated nylon 6 fabric dyed with 2% (owf) C.I. Acid Blue 113 using exhaustion method

Cationic Reagent Rub fastness Wash fastness Perspiration fastness reagent conc., g/L Wet Dry St. Alt Acidic Alkaline St. Alt. St. Alt.

Control - 5 5 4-5 4-5 4 4 4 5

Solfix E 50 5 5 5 5 4-5 5 5 4-5 100 5 5 4-5 5 4-5 4-5 4-5 4-5 150 5 5 4-5 5 4-5 4-4 4-5 4-5

Acramin 50 5 5 5 5 5 5 5 5 berfix K 100 5 5 5 5 5 5 5 5 150 5 5 5 5 5 5 5 4

CTMAB 50 5 5 5 5 5 5 5 5 100 5 5 5 5 5 5 5 5 150 5 5 5 5 5 5 5 5

EL-MOLLA et al .: DYEABILITY OF CATIONISED COTTON AND NYLON 6 FABRICS USING ACID DYES 95

Table 6 — Fastness properties of untreated and treated nylon 6 fabric dyed with 2% ( owf) C.I. Acid Yellow 99 using exhaustion method

Cationic reagent Reagent Rub fastness Wash fastness Perspiration fastness conc., g/L Wet Dry St. Alt Acidic Alkaline St. Alt. St. Alt.

Control - 5 5 5 5 3-4 3-4 3-4 4

Solfix E 50 5 5 5 5 4 4 4 4 100 5 5 5 5 4 4 4 4 150 5 5 5 5 4 4 4 3-4

Acramine berfix K 50 5 5 5 5 3-4 3-4 3-4 3-4 100 5 5 5 5 3-4 3-4 3-4 3-4 150 5 5 5 5 3-4 3-4 3-4 4-5

CTMAB 50 5 5 5 5 4-5 4-5 4-5 4-5 100 5 5 5 5 4-5 4-5 4-5 4-5 150 5 5 5 5 4-5 4-5 4-5 4-5

Tables 5 and 6 show the fastness properties of dyed 4.5 Increasing the number of cationic dye sites in catonized nylon 6. The good wash fastness of acid the cationic cotton may provide more acceptable wash dyes on nylon 6 fabric is due to more electrostatic fastness in the cationic cotton-acid dye system. interactions. Additional factors, such as hydrophobic 4.6 In all cases, the overall colour fastness of interactions and van der Walls forces are also cationic cotton dyes with acid dyes is comparable to important for the bonding of acid dyes to nylon 6 the colour fastness of the same acid dyes on nylon 6. fabrics. These molecular forces are perhaps not as effective between acid dyes and cationic cotton due to References the difference in fibre structure. 1 Kamel M M & Kamel M, Youssef B M & Shokry G M, It is observed from the tables that the fastness to J Soc Dyers Colour, 114 (1998) 101. rubbing (wet or dry), washing, and perspiration 2 Lewis D M & Mcllroy K A, Rev Prog Colour , 27 (1997) 5. (acidic and alkaline) for the cationized samples 3 Renfrew A H M, Reactive Dyes for Textile Fibers (Society for Dyers and Colourist, Bradford), 1999, 168. changes from very good to excellent, but untreated 4 Wu T S & Chen K M, J Soc Dyers Colour, 108 (1992) 388. samples show results ranging from good to very good. 5 Kamel M M, Kl-Kharadly E A, Shakra S & Youssef B M, In all cases, the overall colour fastness of cationic Text Prax Int , 48 (1993) 336. cotton dyed with acid dyes is comparable to that of 6 Veda M & Shin H, Int Dyer , 182 (1997) 36. the nylon 6 dyed with the same acid dyes. 7 Abdel-Hafiz S A, El-Sisi F F, Helmy M & Hebeish A, J Soc Dyers Colour , 112 (1996) 57. 8 Eleftheriadis I C, Koemtzopoulou S A P, Papazoglou V M 4 Conclusion & Kehayoglou A H, J Soc Dyers Colour, 112 (1996) 375. 4.1 The cationic reagents can react with cotton in 9 Liao S K, Cho Y & Chang P S, J Soc Dyers Colour, 116 the presence of alkali by forming ether linkages with (2000) 403. cellulosic fibres, the resultant is a cationised cotton 10 El-Molla M M , El- Sayed H S & El-Halwagy A A, J Text Assoc, Nov-Dec (2004) 165. fabric carrying a positive charges. 11 Hauser P J & Tabba A H, Colour Technol , 117(5) (2001) 4.2 As the cationic reagent concentration increases 282. the nitrogen content of either cotton or nylon 6 fabric 12 Whiteness of textiles, AATCC Standard Test Method also increases, irrespective of the reagent used and the 110-2005 (American Association of Textile Chemist and technique applied. Colourist, USA), 81 (2006) 167. 13 ASTM Standard Test Method D 2654 (American Association 4.3 Acid dyes are only applied to fibres with of Textile Chemist and Colourist, USA), 1994, 1682. positive charges such as polyamide fibres in an acidic 14 Cole L D & Parks C R, Indian Eng Chem, Anal Ed , 21 bath. However, the cotton after cationisation can also (1949) 1861. be effectively dyed with acid dyes. 15 Judd D B & Wyszenki G, Color in Business, Science and Industry , 3 rd edn (John Wiley and Sons, New York), 1975. 4.4 The dyestuff structure and the carionised cotton 16 Standard methods for the assessment of colour fastness of structure play a considerable role in the electrostatic textile, J Soc Dyers Colour , (1995) 24. attraction between the two dyes used. 17 Provost J & Zeneca, Text Chem Colour , 27(1) (1995) 13.