ECONOMICAL DYEING OF POLYESTER -COTTON BLENDS WITH MULTIFUNCTIONAL PROPERTY BY USING CYCLODEXTRINS

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ECONOMICAL DYEING OF POLYESTER -COTTON BLENDS WITH MULTIFUNCTIONAL PROPERTY BY USING CYCLODEXTRINS

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ECONOMICAL DYEING OF POLYESTER /COTTON BLENDS WITH MULTIFUNCTIONAL PROPERTY BY USING CYCLODEXTRINS ABSTRACT The present work illustrates the beneficial effects of applying a hybrid approach which includes the treating of P/C blended material with pure PEG (M.wt.400), PEG solution containing small concentration of NaOH and third one is treatment with CD after the later method. To realise this approach, P/C blended samples were padded in the above mentioned chemicals to wet pick up of 100% (o.w.f), and dried then subjected to saturated steam curing in the appropriate manner. Then the dyeing is performed using HTHP technique. The dyeing liquor was prepared using Dispersing agent, dye solution etc.The pH of the bath was maintained at 5.5 using acetic acid. Well wetted fabric was entered in to the dye vessel and the dyeing is performed for the prescribed time under definite temperature. Finally, the dyed samples were thoroughly soaped with non-ionic detergent (3 g/l of lissapol N), rinsed and dried (for the dark shades R/C treatment was given by using caustic and hydros each 1 g/l at 70 ºC). PEG & CD can be effectively used to dye P/C blends using disperse dyes only. So that it can conserve time, energy, man power etc. Nevertheless, CD plays in the following roles 1) To substitute surfactants in P/C processing; 2) When bound chemically with fibres, it provides hydrophilicity 3) To perform easy removal of sweat and sweat degradation products from the textiles. The successful application of disperse dyes on P/C Blend with the help of PEG & CD bring out numerous advantages such as a) Dyeing of P/C in a single stage process by using Disperse dyes only b)Saving of water, energy, time( due to single stage process) c)Replacing of conventional surfactants & thickeners by CD (It will give low BOD & COD Value than conventional one) d)Enhancement of functional property of the P/C fabric by means of CD e)Minimizing of the effluent problem due to shortening processes, re-placing of surfactants etc f)An economical process etc LIST OF SYMBOLS, ABBREVIATIONS or NOMENCLATURE SYMBOLS, ABBREVIATIONS or NOMENCLATURE EXPLANATION app Approximately BIS Bureau of Indian Standards BOD Biological Oxygen Demand CCM Computer Colour Matching β-CD Cyclodextrins COD β-Chemical Oxygen Demand g/l Grammes Per Liter M.wt Molecular Weight MR Moisture Regain NaOH Sodium Hydroxide o.w.f On Weight of the Fabric P/C Polyester Cotton PEG Polyethylene Glycol pH A measure of Acidity or Alkalinity R/C Reduction Clearing SHPI Sodium hypophosphite W/W Weight / Weight CHAPTER 1 INTRODUCTION The Multifunctional Auxiliaries and Energy Conservation processes are the Prime concern of the Textile Chemical processing industry. Attempts to utilize CD in textile applications started in the late 1980s.This was brought about by the recognition that the inclusion complex formation capability of CD can be applied to the deodorant , aroma, antimicrobial finishes that have recently popular and in treating effluents. Since then research and development of CD applications have become active, and the possibilities of using CD in textile finishing are being explored recently in the textile industry .With the trend in the textile industry demanding high quality and new properties, the range of application of CD is expected in P/C blends dyeing. In this study, for the coloration of P/C blend fabrics, so-called disperse dyes are used, which are very poorly soluble in water(0.1-10 mg/L).Without using solubility-enhancing agents(surfactants),uniform dyeing is not possible. CD however can replace the surfactant, and their COD in the waste water is lower than that of the usual textile surfactants 16 . With the scarcity as well as increasing prices of fuel, it has become one of the imperative duties of the present day researchers to cut-short the processes, without sacrificing the desirable properties of the product for economy in general and conservation of energy in particular. To meet the above objectiveness ,in the dyeing of P/C blends use of high boiling swelling agent like PEG can be used. In conventional process P/C dyeing involves various steps, viz. PET dyeing, reduction clearing, washing, drying; followed by cotton dyeing, washing, drying .If unfixed dyes is not removed properly during soaping/washing treatment will lead to poor fastness properties of the dyed material .Thus ,sever washing-off treatments ,reduction clearing and intermediate dyeing steps are involved in two bath P/C dyeing, which leads to more consumption of time, man-power ,energy and also declination in the productivity. In this study to conserve time and energy, it is desirable to develop an economical process which can dye both the portions of the blend without altering their viz _ properties. Therefore in the present investigation, an attempt can be made to dye P/C blends in a single bath with disperse dyes using high boiling swelling agent (PEG) Normal dyeing of P/C blends involves the elaborated process by using appropriated class of dyes for PET and Cotton portion. The proposed work aims to use Cyclodextrin (CD) and poly ethylene glycol(PEG) as a Pre-treatment to dye both polyester and cotton portion by only disperse dyes in the single stage process. Nevertheless, CD can cause some Multi functional property on the dyed fabric like hydrohilicity, anti soiling etc and the generation of COD and BOD also will be low compare with sodium alginate in the conventional process 31 And use of high boiling swelling agent like PEG is desirable in P/C dyeing to develop an economical process which can dye both the portions of the blend in a single stage with disperse dyes so that it can conserve time, energy, man power etc 1, 34 .As on today commercially, the blends of P/C are successively dyed by two bath process using disperse dyes and cellulosic dyes respectively. Even though one bath processes have been tried using various combinations of cellulosic dyes along with disperse dyes, none of the processes were not successful and are not practical commercially. The successful application of disperse dyes on P/C Blend with the help of PEG & CD bring out numerous advantages such as a) Dyeing of P/C Blend in a single stage Process by using Disperse dyes only b)Saving of water, energy, time( due to single stage process) c)Replacing of conventional surfactants & thickeners by CD (It will give low BOD & COD Value than Conventional one) d)Enhancement of functional property of the P/C fabric by means of CD e)Minimizing of the effluent problem due to shortening processes, re-placing of more polluting surfactants etc f) An Economical process etc.Poly-ethylene Glycol (PEG) & Cyclodextrin (CD) can be effectively used to dye P/C blends using disperse dyes only. Which can alter the nature of polyester & cellulosic fibres contained in the P/C Blends and making it viable to dye cellulosic fibre with disperse dyes along with hydrophobic PET. CHAPTER 2 LITERATURE OF REVIEW 2.1 POLYESTER Polyester fibres are widely used in the textile field, owing to its outstanding characteristics, i.e., high strength, high melting point, better crease resistance, high elastic modulus, better creep properties high wear resistance, better dimensional properties and stable for blending with other type of fibres. However, the fibres have low moisture absorption, high static built-up, high pilling tendency and are difficult to dye under practical conditions due to its compact physical structure and absence of chemical active groups etc. Extensive research has been carried out on the modification of the polymer chain to overcome some of the inherent drawback of the polyester (PET) fibres. It was reported that PET fibres desirable properties can be prepared (a) by modifying the chemical structure of the polymer during polymerization and (b) by modifying the fibre surface and the structure by treating with suitable chemical. In the first method, incorporating additives during the manufacture can modify the PET fibres. The modifying compounds may be mono-functional and di-functional or polymeric compounds 35 . At present this type of polyester fibres are well established commercially 33 . In the second method surface modification of PET fibres have been achieved using various methods such as alkaline hydrolysis 28 graft polymerization of hydrophilic monomers 14 , and steaming 12 Nevertheless, P/C blend enters in market because it has advantages of both PET and cellulose. P/C blend has got lot of advantages from user point of view but from dyers point of view it was difficult to dye the blends. And use of high boiling swelling agent like PEG is desirable in P/C dyeing to develop an economical process which can dye both the portions of the blend in a single stage with disperse dyes so that it can conserve time, energy, man power etc 1,34 Three factors are mainly responsible for making PET fiber difficult to dye: (a) high-fiber crystallinity, (b) a marked hydrophobic character, and (c) an absence of chemically reactive groups in the polymer. Owing to these factors, PET cannot be dyed with the same dyes that are generally employed for cellulosic, protein, nylon, or acrylic fiber. Since the ester groups content of cellulose acetate and polyester fiber is nearly the same (40-45%), attempts have been made to dye polyester fiber with disperse dyes by the same method used for cellulose acetate. However, it was observed that PET was not dyed at 80-100 o C. This was due to a very slow rate of diffusion of disperse dyes into the compact polyester fiber. In the early years attention was directed to finding a means of improving dyeability. The yield of a disperse dye on PET is limited and vastly inferior to the yield on nylon and cellulose acetate because of the low rate of dyeing rather than the low substantivity of early disperse dyes for PET. The problem is solved by using different approaches to increase the rate of dyeing. 1. Building up dye molecules inside PET (azoic dyeing). 2. Opening up the fiber structure to bring down the T g (carrier dyeing). 3. Using temperatures above 100°C [high-temperature (HT) dyeing]. 4. Heating the dye and the PET in the dry state together near the softening temperature of the fiber (thermosol or thermo fixation dyeing). 5. Replacing water with an organic solvent as a dyeing medium (solvent dyeing). Apart from the above approaches, chemical modification of PET (to impart affinity for dyes other than nonionic dyes is commercially practiced in order to get cationic dye able PET. Similarly, the transfer printing process is used to colour polyester in solid shades. The use of solvents for dyeing PET is intensively investigated in the early 1970’s. Even though PET can be dyed to any depth of shade using solvents, none of the solvent dyeing methods ever reached a state of a commercial feasibility. The azoic dyeing process was once used to colour PET, but with the development of disperse dyes and various dyeing methods; it has now lost its importance. It is now used mainly to produce black shades. 2.2 DYES FOR POLYESTER PET is now dyed with nonionic dyes specially synthesized to suit the dyeing processes. Nonionic dyes with low aqueous solubility at dyeing temperatures (100- 130 o C) are the best dyes for PET. The solubility of nonionic dyes in water is low such that these dyes are considered water insoluble. It is essential; however, these dyes should have some solubility in the dye bath to get dyed in the aqueous bath. These dyes are applied in the form of an aqueous dispersion. The small aqueous solubility and the particle size of a disperse dye plays a vital role in the rate of dissolution and the rate of adsorption of dye by PET. Dispersing agents play a vital role in dyeing process. Some disperse dyes are sensitive to heavy metals and form chelated compounds with calcium ions giving tonal variations. Soft water is therefore used for dyeing. Disperse dyes are available in two forms-micro disperse granules or powder and liquid dyes. The dispersion of a dye is spray dried to get solid granules and powders. The amount of dispersing agent required to get stable dispersions can be 40-90 % and usually 60% of the dried disperse dye- powder. This large proportion of a dispersing agent in the granules and powders of disperse dyes creates problems such as increasing aqueous solubility, inducing migration during drying of padded goods, lowering the exhaustion of dye bath and so on. The properties expected of micro disperse -dye granules include stability, dryness, uniformity, free flowing, non-dusting, and non-hygroscopic nature, good bulk density (app.0.5 or more), and ready dispersibility. Liquid dyes are dispersions with a low concentration of a dispersing agent. Dispersion stability, easy miscibility, proper pH., and free flowing nature are some of the prerequisites for liquid dyes. Since metering pumps can be used for liquid dyes the additions, weighing and so on not pose no problems. Liquid dyes are easy to dissolve and to use. They pose none of the problems that arc associated with the granular dyes. However liquid dyes are likely to dry up to settle, and to alter in concentration during storage. Special precautions are required to store and handle liquid dyes. Many times, disperse dyes have poor storage stability, particularly, if they are exposed to a humid atmosphere. Under these conditions, the dispersion breaks into lumps. Such a dye is likely to give uneven, specky dyeing. The state of the dye dispersion can be easily checked by dispersing the dye in water and dropping it on filter paper. If the dispersion is good, no particle will be visible on the filter paper. Improvements in the physical form of the dyes improve the final color results. Chemically, the disperse dyes come from various classes Such as azo, anthraquinone. Methine. and diphenylamine. The dyes usually have NO 2 , CN, OH, halogen and primary, secondary, and tertiary amines groups but they never have any polar groups which easily ionize in an aqueous bath. Some of the dyes have a free COOH group. Such dyes are usually applied by printing techniques under acidic pH so that this group does not ionize substantially. Free aliphatic hydroxyl groups that impart high aqueous solubility are esterified with acetic acid or a mixture of acids. These dyes generally have low molecular weight which facilitates their entry and diffusion into the highly crystalline polyester fiber. The higher the molecular weight of the dyes, the slower is the diffusion in the fiber. They have significant, though low vapor pressure. Particularly at elevated temperatures. Disperse dyes are sensitive to pH. Methine dyes hydrolyze or dimerize under alkaline conditions. The pH the dyebath for dyeing PET is therefore maintained on the acid side. A redox buffer is usually also added to the dyebath to avoid reduction of disperse dyes 25 The fastness properties and dyeing characteristics of disperse dyes are considered with particular reference to the subsequent treatments. In the case of yam dyeing and. to a lesser extent, piece dyeing, wet fastness after heat setting is important since the knitting or coning oils on dyed goods can lead to the migration of the dye into the oil. Besides the usual light and wash fastness, the sublimation fastness of disperse dyes is very important since dyes of low sublimation fastness give problems during subsequent treatments such as resin finishing. A similar high standard of fastness is required for dry and wet rubbing. Migration of dye to the surface of the fiber during the heat-setting process frequently results. Dyes with high sublimation fastness are therefore used for the dyeing of yarns. Similarly, dyes, auxiliaries and dyeing conditions are selected to give optimum coverage of small variations in dye affinity of textured yarns. Thus; dyes used for yarn dyeing must meet the following specifications: 1. Good dispersion properties, so that the dye is not filtered on a package of yarn that constitutes an effective filter. Paste brands of disperse dyes are usually preferred for yam dyeing. 2. Good stability in HT bath during dyeing (130°C/2 h). 3. Good leveling properties, at least with the addition of a surface-active agent. Use of certain carriers help in getting level dyeing of a yarn package. 4. Good sublimation fastness. 2.3 MECHANISM OF DYEING The mechanism of dyeing PET with nonionic dyes under different conditions of dyeing has some common features and some significant differences. HT dyeing and carrier dyeing involve dye transfer from aqueous baths, while in thermo fixation dyeing; the water in the pad liquor is completely expelled by a drying process before the dye is fixed on PET. The contribution of the PET structure to the dyeing mechanism remains the same for the three processes because the fiber does not absorb any significant amount of water and the presence or absence of water on the fibre does not play any significant role in the sorption of dye by PET. The dye is adsorbed only in the amorphous regions of PET, that is, it does not enter the crystalline regions. Thus, if calculated on the basis of the amorphous content of the PET materials, the fiber saturation values of a dye on different PET materials are similar (FIG.2.1). The percentage composition of the crystalline and non-crystalline regions in the fiber may vary from fiber to fiber and the fiber may exhibit apparent differences in its dyeing behavior. The penetration of dyes in the PET structure is explained by the free volume theory for the low-molecular-weight compounds in an amorphous polymer. The energy effects in dyeing show abrupt changes over a very short range of temperatures at T g . FIG.2.1 Temperature dependence of true saturation values of dyes on polyester material. [...]... formed by the vibrations of the chain segments of PET molecules, the shape and size of the dye molecule influences the rate of dyeing The higher the molecular size of dye, the higher is the space required for the dye of diffuse Because of this, as the temperature increases, the effect of the size of a dye molecule on the rate of dyeing decrease; that is, the activation energy of diffusion increases with. .. calculated for three polyesters on the basis of their amorphous content when the data on all polyesters lie on the same plot The concerted movements of Chain segments of polymer molecules are started at T g An increase temperature of above Tg, raise the frequency and amplitude of the movement of chain segments This facilities diffusion of dye and the rate of diffusion increase with the temperature... saturation values This is also the case with dyeing from an organic solvent 7 2.4 HT Dyeing The mechanism of dyeing PET with nonionic dyes in an aqueous dispersion has been investigated by many workers Earlier investigation shows that dyeing involves the attraction of positively charged particles of suspended dye to negatively charged fiber surfaces to build up a surface layer of dye particles Subsequently,... with the molecular weight of the dye The rate and extent of absorption of a dye are dedicated by the fiber structure, time and temperature of aqueous dyeing or thermo fixation 9 Disperse dyes are combined to produce mixed shades Neither the rate nor the equilibrium adsorption of dyes in mixture is influenced by the presence of the other dye 8The dyes build up on PET, independent of each other, up to their... no dyeing results However, the pore size in the fibre structure probably reduces in the presence of PEG, thereby allowing dyeing to occur On the other hand, the compact structure of polyester allows minimum pore size available for the penetration of dye molecule It is well established that for polyester, penetration of disperse dyes is more prominent at higher temperature due to more availability of. .. presence of PEG hinders the usual penetration of the dye molecules Effect of CD’s conc on Dye exhaustion (E %) and Colour strength (K/S) of treated and untreated P/C Blends dyed with Disperse dyes CD C Conc (gpl) 0 10 15 20 30 35 E% 24 37.8 44.2 48.2 52.5 52.1 K/S 2.4 4.2 4.8 4.2 5.2 5.2 Effect of Treatments on Dye exhaustion (E %) and Colour strength (K/S) of treated and untreated P/C Blends dyed with. .. hydrolysis of polyester takes place not only at their free ends, but also in other positions, thereby the increase in carboxylic content was continued and reached 290.6 m.eq./100 gr.treated samples The colour strength of samples dyed with basic dye is thus indication of hydrolysation and it can provide an assessment of the degree of hydrolysis It was found that K/S increased as the concentration of carboxylic... not exhibit any influence on the overall rate of dyeing and the diffusion of dyes within the fiber is the rate determining step Disperse dye has a tendency to deposit on the fiber surface In the course of dyeing, this deposited dye has to be desorbed to migrate to some other part of the fiber material to get the level uniform dyeing 22 This prolongs the dyeing process Significant surface deposition... improving fixation of disperse dyes to specific fibre type For example , cellulosic and cellulosic fibre blends exhibit improved dye ability when concentrations of up to 10% PEG(av M.w of 100-600) were used in the dye bath 26 Similar improvements were observed when PEG was used as dye bath additives in the dyeing of P/C fabrics with disperse dye 20 Cyclodextrins can be considered as a new class of Textile... steaming Fig-4 SEM for the surface of Samples Treated with a mixture of PEG and Sodium hydroxide solution (95.5%/4.5% w/w) to wet pick-up of 100 % expression then steaming Fig-5 SEM for the surface of Samples Treated with a mixture of PEG and Sodium hydroxide solution (95.5%/4.5% w/w) to wet pick-up of 100 % expression then steaming at 160º C for 2 min ; treated with CD then curing at 170º C for 2 . ECONOMICAL DYEING OF POLYESTER /COTTON BLENDS WITH MULTIFUNCTIONAL PROPERTY BY USING CYCLODEXTRINS ABSTRACT The present work illustrates the beneficial effects of applying a. least with the addition of a surface-active agent. Use of certain carriers help in getting level dyeing of a yarn package. 4. Good sublimation fastness. 2.3 MECHANISM OF DYEING The mechanism of dyeing. application of disperse dyes on P/C Blend with the help of PEG & CD bring out numerous advantages such as a) Dyeing of P/C Blend in a single stage Process by using Disperse dyes only b)Saving of

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  • LITERATURE OF REVIEW

  • 2.4 HT Dyeing

  • CHAPTER – 4

  • Bureau of Indian Standards.,(2001).,Handbook of Textile Testing, Part 4 Identification and Testing of Dyestuffs and Their Colour Fastness on Textile Materials( First Revision), Published by Bureau of Indian Standards, New Delhi 110002 ( July 2002), (Washing: IS: 687-1979 pp.137-138), (Rubbing: IS: 766 – 1988pp. 193-194),( Sublimation: IS: 975-1988 pp.203-204)

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