Vol. 6, Issue 24, October 2013

Exclusive Insight

Chemistry behind good feelings Contents

Reduction Clearing Agent for Polyester

Clearnon-GRE

Reactive -fixing agent for Cotton

Fixanol (Conc)

Acid Donor for Polyamide

Acidon-PA

Hydrophillic Silicone Softener

Hydrosoft-142

2 Saraquest, Issue 24 , Oct 2013 REDUCTION CLEARING AGENT FOR POLYESTER

CLEARNON-GRE

Although synthetic fibres are the product the largest commodity fibre in the the boil in the presence of an of 2nd generation, in present global synthetic fibre world, thereby polyester accelerating agent or 'carrier'. Disperse scenario, they are vastly employed in production exceeds than both can also be transferred to both apparel and non apparel sector. polyamide and polyacrylic fibres polyester by padding application and Among the synthetic fibres polyester is curing at temperature in the range of the most important and widely used due Polyester fibres are hydrophobic and 190-2100C. to its high strength, good elastic recovery, absorb very small amount of water and dimensional stability, abrasion there is no significant change in their High temperature exhaust is the resistance, resiliency, as well as tensile properties in wet conditions. The most widespread method of batch suitability for blending with natural fibres. moisture regain of polyester fibre is coloration. The temperatures require approximately 0.4 % at 65 % relative pressurized equipment and impart Polyester is a term often defined as “long- humidity at 20 0C. Polyester materials increased diffusion of the dyestuff (and chain polymers chemically composed of dries quickly because of their very LOW therefore increased rate of dyeing) by at least 85%by weight of an ester and a water absorption. Polyester fibres show reducing cohesion between polymer dihydric alcohol and a terephthalic acid”. outstanding resistance to damage by chains and increasing the kinetic energy In other words, it means the linking of most common chemicals under of the dye molecules. The three main several esters within the fibers. Reaction ordinary conditions of exposure and a phases of the process includes the of alcohol with carboxylic acid results in wide range of substances such as heating or adsorption phase (from 60 0C the formation of esters. oxidizing and reducing agents – 125 0C) and at 130°C diffusion and migration for 20-30min followed by Polyester fibre is one of the important Disperse dyes are the most important reduction clearing process. synthetic fibre. Polyester has high class of dye used in dyeing polyester chemical resistance , high moth fibres and provide a wide range of hues Disperse dyes have limited solubility in proofness , excellent wash and wear with good build-up and fastness water therefore unfixed disperse dyes and permanent press characteristics. properties.The rate of dyeing may be remains on to the fibre surfaces after Polyester fabric when blended with raised to the level of commercial dyeing, which will considerably reduces cotton and , gives rise to high quality acceptability, either by raising the wet fastness, sublimation, dry cleaning fabric. These unique properties make it temperature to 1300C, or by dyeing at fastness as well as dulling of the shades

3 Saraquest, Issue 24, Oct 2013 These dyes particles have to be removed Research indicates that the polyester In order to overcome drawbacks of from the surface as it will considerably dyer will typically reduction-clear in the caustic & hydros, Sarex has developed results in: range of 30-50% of production shades eco-friendly clearing agent Clearnon- · Poor wash fastness and sometimes an even higher GRE for removal of unfixed disperse · Poor sublimation proportion in blend dyeing. Minimizing dyes from dyed polyester fabrics · Reduced dry-cleaning fastness the need for reduction-clearing can lead · Dulling of shade t o s u b s t a n t i a l p r o d u c t i v i t y Unique Feature of Clearnon-GRE · Cross staining in case of polyester improvements and water and chemical blends savings as well as a reduction on the ·No obnoxious smell and no effluent load and should be a key sulphur present and product is In order to remove unfixed objective in implementation of a rapid eco-friendly. conventional reduction clearing is dyeing approach for polyester. ·It works under mild alkaline to carried out with caustic & hydros acidic conditions thereby (Sodium dithionate) at 70°c for 10-20 Reaction during Reduction Clearing reduces TDS mins. with hydros ·A separate neutralization step is not require as against caustic & The treatment with caustic & hydros Hydros. often sufficient to clear the fibre surfaces ·It reduces time as after dyeing but the ease of removal varies from in the same bath Clearnon- chromopore of the dye. GRE is added ·Saves water, energy & time. Most of the disperse dye contain the azo group( –N=N–). This group easily gets Application: decomposed into amino groups on For medium depth of shade treatment with caustic & hydros as a Clearnon-GRE : 0.5 - 1.5 g/l reducing agents. Generally reduced Drawbacks of sodium dithionite : amino residues are colourless to light For deep shades colour depending upon the chromophore · Can produce sulphite and sulphate Clearnon-GRE : 1.5 - 2.5 g/l of dye. Disperse dye also contains · High concentrations of sulphate can After treat for 10-20 mins at 70-800C, anthraquinone type of chromophore cause damage to unprotected rinse hot and cold. which is difficult to reduce and is not concrete pipes. destroyed during normal reduction · Toxic . Benefits of using Clearnon-GRE: clearing treatment but it changes into · Unpleasant odor. 1. Reduction clearing can be done in soluble sodium leuco form of · Corrosion of the effluent drainage same dyebath with Clearnon-GRE. anthraquinone which can be system. 2. Eco-friendly process. subsequently washed away. · Damage to the treatment works and 3. Saves water, energy and time. the often associated high pH

4 Saraquest, Issue 24, Oct 2013 Study of Clearnon-GRE against Conventional Method a) Reduction Clearing Conventional Process (2 g/l Caustic & 2g/l Hydrosulphite) Maroon and Dark Navy depth of shades were used for study . 1300C , 45 min Dyeing of polyester fabric was carried out at pH 4.5 , 800C , 25 min 10-20 min 1300C for 45 min. 500C , 10 min Reduction Clearing: Reduction clearing was carried out as per process shown in fig 1a(Conventional) and Fig 1b (With Clearnon-GRE)

Washing Fastness: The washing fastness was evaluated by ISO 105 C06 C2S (Fig.2)

DYEING R/C HOT WASH NEUTRALIZE Fig.2 Indicates that washing fastness of fabric treated with Clearnon-GRE is comparable to b) Reduction Clearing by Clearnon-GRE caustic and hydros for both the shade studied.

1300C , 45 min

800C , 20 min Rinse-cold (If required)

R/C

Clearnon-GRE 2 g/l DYEING 0.5 g/l

Fig 1 : Process flow diagram of Dyeing of polyester followed by Reduction clearing with a) Conventional method b) 2 gpl Clearnon-GRE

Staining on Multifibre a 2 g/l Caustic & 2 g/l Hydros 4 4-5 4-5 3-4 4.5 3-4 b

2 g/l Clearnon-GRE 4-5 4-5 4-5 3-4 4.5 4 c 2 g/l Caustic & 2 g/l Hydros 4 4-5 4-5 4 4.5 4 d

2 g/l Clearnon-GRE 4-5 4-5 4-5 4 4.5 4-5

Fig 2 : Wash fastness rating on Multifibre with Clearnon-GRE (ISO 105 C06 C2S) a) Maroon shade (conventional R/C) b) Maroon shade( R/C with Clearnon-GRE) c) Dark Navy shade (conventional R/C) d) Dark Navy shade ( R/C with Clearnon-GRE)

4 Saraquest, Issue 24, Oct 2013 REACTIVE DYEFIXING AGENT FOR COTTON : FIXANOL-CONC

Cotton known as the king of fibres From 1930 onwards, cationic dye fixing Unique features of Fixanol (conc) accounts for more than 50 % of fibres agents have been fully exploited to · Ecofriendly, formaldehyde usage in both for apparel and complex dyes for improving fastness of free. non-apparel purpose. Several classes dyed fabrics. However, these were · Improves washing fastness of dyes can be used to dye cellulosic primarily based on formaldehyde and water contact. fibres, namely direct, vat, reactive and condensation resin products and it is · Does not effect either light sulphur. The choice of dye class used seen that fabrics treated with these fastness or the shade of depends on factors such as their cost , products release formaldehyde into the treated material. ease of application and fastness atmosphere directly or during · Can be applied by exhaust as properties. processing and release formaldehyde well as pad. fabrics/garments. Formaldehyde Reactive dyes furnish a broad gamut of causes allergic reactions to skin on Application: shades with good light and excellent contact, demand for non formaldehyde Exhaust application wash fastness on cellulosic fibres, thus based fixing agents increased. After thorough soaping to remove are widely used to dye cellulosic fibres. However, because of the health hydrolyzed reactive dyestuff from dyed The main drawback is that it can react problems associated with formaldehyde or printed material, treat in a fresh bath not only with the fibre but also with water there is a market demand for non- with: present in dyebath and forms a formaldehyde dye fixing agents. Use of hydrolysed dye. In order to remove fixing agents on reactive dyed goods Fixanol (Conc) = 0.5- 2 % unreacted & hydrolysed dye from lead to improvement in contact water pH = 5 -5.5 fabrics, it is subjected to several and wash fastness. The extent of Temperature = 400 C for 15-30 min. washing off treatments or dyefixing improvement will depend on the dye and agent are applied for fixing of dyes. depth of shade. Continuous application: Although, washing off process is most Fixanol (Conc) = 5-20 g/l preferable but it is costly and time Sarex has developed concentrated non In padding alone or with other finishing consuming than dye fixing of reactive – formaldehyde dye fixing agent chemicals or on continuous soaper in dyed materials. Fixanol (conc) for reactive dyes. last chamber, pH 5-5.5 with acetic acid, at 35-400 C.

6 Saraquest, Issue 24, Oct 2013 Washing fastness study of dye - fixed WASHING FASTNESS BY ISO 105 C 03 fabric. The fabric was dye fixed with Fixanol DYED STAINING ON COTTON STAINING ON MULTIFIBRE (conc)by exhaust application at 0.4 % and COTTON 0.8 % concentration , pH- 5- 5.5 , M:L 1: 10 , BLANK Temperature 40 0C for time – 30 minutes The dye-fixed fabric was evaluated for 0.4 % fastness by ISO 105 C03 and E01(Fig 1) FIXANOL (CONC) Fabrics dye fixed with Fixanol (conc) 0.8 % shows no staining to very slight FIXANOL staining on multifibre depending on (CONC) concentration. WATER CONTACT BY ISO 105 E 01 Shade variation study of dye fixed DYED COTTON STAINING ON MULTIFIBRE fabric Cotton fabrics were dyed with various class BLANK of reactive dyes and then dye fixed with Fixanol (conc). The shade change were 0.4 % FIXANOL determined. (CONC) All the dye fixed fabrics do not show any 0.8 % shade changes irrespective of classes FIXANOL of dyes and concentration of Fixanol (CONC) (conc) (Table 1-4) Fig 1 Washing fastness by ISO 105 C03 &E01

FN Class 1.5 %Cibacron Yellow FN2R + 1.5 %Cibacron ME Class 1 % Yellow F3R + 1 % Red F3B + 1% Blue Red FNR + 1.5 % Cibacron Blue FNR BRF Dye Fixing Dye Fixing Agent Strength DE Da Db Agent Strength DE Da Db Soaped Soaped Sample 100 - - - Sample 100 - - - 0.25 % 0.25 % 104 0.480 0.096 0.293 103 0.386 -0.270 0.037 Fixanol(Conc) Fixanol(Conc) 0.5 % 0.5 % 102 0.287 104 0.566 Fixanol(Conc) 0.136 0.173 Fixanol(Conc) -0.264 0.067 1.0 % 105 0.719 0.349 0.010 1.0 % 101 0.321 -0.191 -0.261 Fixanol(Conc) Fixanol(Conc) Table 1 Shade changes and colourant strength of fabric Table 2 Shade changes and colorant strength of fabric with dyed with Cibacron FN dyes ME Dyes Vinyl Sulphone 1.0 % G.Yellow RNL + 1.0 % Blue BB HE Class 1 % Yellow HE4R + 1 % Red HE3B + 1 % Blue Dyes + 1.0 % Red CRBL HERD Dye Fixing Dye Fixing Agent Strength DE Da Db Agent Strength DE Da Db Soaped Soaped Sample 100 - - - Sample 100 - - - 0.25 % 0.25 % 104 0.651 0.352 0.375 101 0.230 0.033 0.163 Fixanol(Conc) Fixanol(Conc) 0.5 % 0.5 % Fixanol(Conc) 104 0.559 -0.026 0.215 Fixanol(Conc) 102 0.320 0.259 0.016 1.0 % 104 0.631 -0.239 0.255 1.0 % 102 0.629 -0.017 -0.477 Fixanol(Conc) Fixanol(Conc) Table 3 Shade changes and colorant strength of fabric with Table 4 Shade changes and colorant strength of fabric with Vinyl Sulphone Dyes HE Dyes 7 Saraquest, Issue 24, Oct 2013 ACID DONOR FOR POLYAMIDE : ACIDON PA

Polyamide is the first commercially At the end of dyeing process, a dyes in a conventional system. Although successful synthetic polymer. It is thermodynamic equilibrium is the pH – sliding takes longer and require condensation co-polymer formed by established between the dye dissolved s buffer and a control unit , it has proved reacting diamine and dicarboxylic acid. in the liquor and the dye diffused into the effective , especially for shades where it The fibre has outstanding durability and fibre. Incase of polyamide dyeing with is difficult to achieve level dyeing . The excellent physical properties. The amide metal complex / acid dyes , the two process also improves reproducibility group forms hydrogen bonding between types of processes are used viz. because it raises bath exhaustion. polyamide chains, imparting high constant pH process and sliding pH strength at elevated temperatures. The process . Specifically, increasing the temperature polyamide fabric has good strength, of the dye bath increases the diffusion compact molecular structure, resistance During dyeing of polyamide, the rate, while controlling the pH controls the to sunlight, softer hand, higher melting polyamide materials are placed in a dye number of dye sites that are available for point, excellent abrasion resistance. bath initially containing an acid dye and receiving the acid dye. At higher pH's, the an acid donor sufficient for dye dye is not readily accepted by the P o l y a m i d e f i b r e s h a v e b e e n exhaustion. When the dye bath polyamide fibre. At lower pH, equilibrium conventionally dyed using acid and temperature is increased the pH shifts and the dye becomes strongly metal- complex dyes by polyamide is gradually reduces and allow dye attracted to the polymer. temperature – dependent. The fibre takes diffusion of dyes. up the dye at temperatures above the glass transition point at which the Ideally , the pH of the bath is dropped at segments in the polymer chains become a rate which causes the dye to slowly more mobile at higher temperatures. The diffuse into the polymer substrate . if the fibres open and allow the dye , which pH can be effectively controlled , the dye attracted to the positive charge on the becomes evenly distributed throughout amino end groups in the fibre to penetrate the bath and substrate and is absorbed the polyamide. The dye is then bonded to by the substrate uniformly which the fibre through intermolecular forces. ensures uniform and reproducible shade against as against the rushing of

8 Saraquest, Issue 24, Oct 2013 Features and advantages of sliding pH bath exhaustion increases but Sarex has developed a unique acid process against constant pH process the migration and diffusion donar – Acidon – PA · Constant pH process ensures requires longer time. In case dye exhaustion onto the sliding pH the exhaustion is Acidic pH is obtained with increase in substrate by raising the controlled thus , migration and temperature unlike conventional buffer temperature while sliding pH diffusion requires less time. which maintained pH irrespective of process achieves exhaustion · The critical temperature range temperature. Acidon - PA is used for by combination of raising depends on the pH and in case dyeing of polyamide ,wool and their temperature and reducing pH . of sliding pH process critical blends with acid dyes. · Incase of constant pH process range temperature is higher suitable dyes with good than for the constant pH Unique feature of Acidon-PA compatibility is required and /or process . Robust technology with low auxillary to improve the affinity · A higher rate of heating upto maintenance required of the dye . while in case of the critical temperature range User Friendly and can be dosed sliding pH system irrespective can be used for sliding pH of the type of dye we will system than when using Application : achieve uniform dyeing. constant pH process , thus Dyeing of polyamide · In constant pH process rate of reducing total process time. Acidon – PA : 0.1 – 0.5 g/l

Table : 1 results of bath pH at different temperatures and concentrations

Table 1. indicates that initial pH 7.5 with increase in temperature to 90 0C for 30-45 minutes reduces to pH 5.28 , 4.67 and 4.3 at 0.1g/l ,0.2g/l and 0.5g/l respectively , which is required for the dyeing of polyamide.

Fig 1. pH versus temperature at various concentration of Acidon – PA

8

7.5 7

6.5

6 Acidon PA 0.1g/l 5.5 Acidon PA 0.2g/l Acidon PA 0.5g/l 5

4.5

4 Room 50deg 70deg 90deg 90/30' 90/45' Temp

9 Saraquest, Issue 24, Oct 2013 HYDROPHILLIC SILICONE SOFTENER HYDROSOFT-142

Softeners have gained great importance Functional textiles have to meet ever to epoxy and glycol makes it water in finishing; almost no piece of higher demands. A good towel should l o v i n g . A l s o s o f t n e s s a n d textile leaves the production facilities be both extraordinally soft and hydrophilicity are at two extreme ends. without being treated with a softener. hydrophilic. The same applies to If we increase softness, hydrophilicity This softening treatment is to give the modern clothing textiles: the wearer decreases.(Fig. 1) textiles the desired handle, A nice, soft expects a soft hand combined with optimal moisture management. handle is often the decisive criteria for Nowadays, no consumer will wear a A unique combination of long chain buying a textile and is therefore of most garment which doesn't feel good silicones and polyether glycols gives vital importance for marketing textiles. because it scratches or rubs,due to less rise to extremely flexible chains which softness, although offers perfect imparts soft handle coupled with Silicones permits unmatched effects hydrophilicity. hydrophilicity. such as softners, hydrophilicity, body to Sarex has developed a new mention just a few. The silicone The trend in modern textile finishing is generation hydrophillic micro softeners generally consists of linear definitely toward softness and polysiloxane softener Hydrosoft- aminopolydimethylsiloxanes. Basic hydrophilicity – a combination can 142. which combines and optimally units differ in the chain length, the achieved by right type of silicone balances softness and hydrophilicity. number of functional side groups and the softener. chain ends. The amino functional side groups results in optimum distribution of Generally silicones show no affinity the silicone on the fibre surface and thus towards water. But chemical ensures maximum softness. Amino modification of polydimethyl siloxanes functional silicone fluid impart a soft hand much more effectively than their methyl counter parts or silicone with caboxyl or epoxy group. Addition of polyglycol chains, pyrrolidone groups imparts hydrophilicity. Hydrophilic silicones differ from conventional silicone by greater compatibility with aqueous system. Fig 1. Relationship between softness & hydrophilicity

10 Saraquest, Issue 24, Oct 2013 Fig.2 Relationship between structure and properties of silicons

Hydrophilic segments directly attached Polymer strongly fixed on fiber Hydrophilic moieties far away to fiber surface surface from fiber surface. Very high hydrophilicity. It is not the best way to get Very high wash fastness Silicon segments exposed and far away hydrophilicity Old technology from fiber surface so got very soft feel Forms surfactant-like structure results in good stability.

Unique feature of Hydrosoft-142 Application: Exhaust application ·It gives inner softness and Hydrosoft-142 : 2-4 % outer smooth surface. ·It is suitable for exhaust as pH 5.5 - 6.0, Temp - 35 to 400C, treat for 20- well as pad application. 30 mins. ·Applicable on terrytowels, cotton knits and woven fabric. Pad application ·Fabric finished with Hydrosoft-142 : 20-40 g/l Hydrosoft-142 leads to soft, pH 5-6, pad with 65-70 % pick up, dry at hydrophilic finish. 140-1600C.

11 Saraquest, Issue 24, Oct 2013 Want to know more ? Sarex Chemicals