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The Pretreatment and Dyeing Technology of High-count Cotton Yarn Vector-based Water-soluble Polyvinyl Alcohol Fiber

Author: XuDouFeng
Tutor: HeZuoZuo
School: Donghua University
Course: Textile Chemistry and Dyeing and Finishing Engineering
Keywords: High-count cotton yarn Water-soluble PVA fiber Yarn dyed fabric Carrier Dissolving the carrier fiber Breaking strength
CLC: TS184.13
Type: Master's thesis
Year: 2011
Downloads: 64
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Abstract

The yarn dyed fabric products possess the characteristics of rich patterns, variety of colour styles,excellent and inexpensive performance, so widely used for textile materials and decorative cloth in domestic and foreign markets.The yarn dyed fabric weaving with high-count cotton yarn not only has excellent properties such as higher water absorbency and moisture,being comfortable to wear for cotton cellulose, but also has soft flimsy, brightly coloured and lustrous, and good color fastness. However, the high-count cotton yarn is difficult to weave for its high fineness and weak strength, and usually blend with water-soluble PVA fiber to enhance its strength,then dissolving the carrier PVA fiber followed dyeing and finishing processing,and achieve the development of high-count cotton yarn dyed fabric.There are two schemes of dissolve the carrier PVA fiber:the one is dissolving between spinning and dyeing stage,the other is dissolving followed dyeing and weaving process. This research study the two above-mentioned schemes by through evaluate breaking strength and dyeing properties of high-count yarn,and confirm the optimal dyeing and finishing process.To realize the dissolve carrier PVA fiber efficiently and conduct dyeing and finishing process rationally, this paper firstly study on the change of micro-morphology and construction of water-soluble PVA fiber in dissolving process and its influencing factors.The swelling-dissolution process of fully hydrolyzed PVA fiber was investigated by optical microscope(OM) and X-ray diffraction(XRD). The effects of dissolution temperature and time, sodium hydroxide,ammonia water and hydrogen peroxide concentrations on the dissolving capability of PVA fiber were discussed. The results showed that the solvent penetration into the inside of PVA fiber, weaken the hydrogen bonding of amorphous portion, and caused the PVA fiber swelling. PVA fiber dissolved completely followed crystal region were destroyed by absorbing enough energy. Temperature and time were the main influencing factors on the PVA fiber dissolving. The ion agglomeration result from the sodium ion within the PVA fiber would hinder its further dissolving. The oxidation of hydrogen peroxide, which could cut down the molecule chain of PVA fiber and reduce its degree of polymerization, increase dissolving capability.In the study of high-count cotton yarn vector-based water-soluble PVA fiber firstly dissolve the carrier fiber and then dyeing stage, spectrophotometer was used to quantitatively characterize the extent of dissolution of co-spinning PVA fiber.The dissolving process and dissolving technology were discussed and optimized.The result showed that the dissolution of co-spinning PVA fiber caused high-count cotton yarn shrink in length, which decreased the spacing resistance among fibers, and increased diffusion rate of PVA solution,then adsorptive PVA molecule extrication from cotton fiber and achieved dissolution process through oscillatory washing.The best dissolving process of carrier PVA fiber was dissolved in water solvent without any other additive, yarn sample was soaked into water at room temperature and heated at rate of 1℃/min to 100℃,20min constant temperature for fully dissolving at 100℃,then oscillatory washing at 80℃and 60℃hot water for 3min,room washing till without bubbles appearance.The high-count cotton yarn was treated with sodium hydroxide scouring and hydrogen peroxide bleaching in one bath for low damage after dissolving the carrier PVA fiber, and dyed with high absorbtion fluorine-functional reactive dyes.Breaking strength retention of high-count cotton yarn decreased rapidly to 50.8%after dyeing process than yarn sample without dissolving the carrier PVA fiber.In the study of high-count cotton yarn vector-based water-soluble PVA fiber firstly dyeing and then dissolve the carrier fiber process, mainly analyzed the influence from the pretreatment to the yarn, investigated the effect of various factors during the dyeing process, and compared the K/S value after the dissolving process.The results showed that the yarn treated with low temperature bioscouring and hydrogen peroxide/TAED bleaching had excellent capillary effect and whiteness. The yarn strength displayed no significant reduction, and was better than that of pure cotton yarn after dyeing, and the yarn fastness was close to that of pure cotton yarn. The dye fixation rate was slightly lower than that of pure cotton yarn because the exhaustion rate of the reactive dyes on the PVA fiber was low. The optimal comprises treatment of high count cotton yarn vector-based PAV fiber with an aqueous formulation consisting of alkaline pectinase enzyme 1g/L,TAED15g/L,H2O2 6g/L,The treatment is carried out bioscouring at 60℃for 60min,and then bleaching at same time and temperature. Its best dyeing conditions is studied and gave as: mid-temperature bifunctional reactive dyes,2% o.w.f, treatment at 70℃.In the study of intermeditate production of high-count cotton yarn dyed fabric vector-based water-soluble PVA fiber,effect of rolling density in soft rewinding process on dissolution co-spinning PVA fiber and dyeing high-count cotton was analysized. Used titration onling in dissolution process,and optimized technique of dissolution co-spinning PVA fiber,dyeing and weaving, and achieved the intermeditate production of high-count(360s/3) cotton yarn dyed fabric successfully.

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