In order to fully improve the added value of colored product, except add patten, high-count yarn & blended yarn and special dyeing process can also be used to achieve a unique style of colored cloth. Pure cotton blended yarn-dyed fabric: soft feel, breathable, strong water absorption. In recent years, it has been favored by the majority of consumers. Color cotton by mixing cotton, carding cotton, spinning, weaving to eliminate color difference, it is convenient production.
RAW MATERIAL REQUIREMENT
1. Raw cotton requirement
After the raw cotton dyeing, the color cotton should be mixed, combed, spun, and finally woven/knitted, and the requiements of color difference is not strictly, so it is suitable for any variety of raw cotton.
2. Dye compound
The dyestuffs and auxiliaries are used for cotton bleaching and dyeing: with fine particles and soluble in water, good diffusion and permeability.
DYEING
In order to obtain better color mixing effect of cotton textiles, pay attention to two important points in raw cotton dyeing: remove natural impurities of loose fiber and spinnability of dyed cotton fiber.
1. Pretreatment
Cotton fibers contain many symbionts, such as waxes, nitrogen, pectin, minerals and natural pigments, cottonseed shells, etc. The existence of these symbionts will seriously affect the wettability of cotton fiber, making it difficult to dyeing, so it must be removed first. The pre-treatment of raw cotton dyeing: boiling and bleaching and related washing. The purpose is to remove cotton impurities, fruit gum and natural pigments that hinder dyeing. After boiling and fully washing, it is necessary to check whether the concentration of alkali, residual hydrogen peroxide and whiteness meet the process requirements or not. Generally, the whiteness of the cotton fiber after pre-treatment are consistent, and the pH value is neutral.
2. Raw cotton dyeing
Using direct dyes and reactive dyes, considering the color fastness and convenience of use, using reactive dyes is better, because reactive dyes with bright color, complete chromatography and a certain wet processing fastness. The process control is stable and appropriate additives, the reproducibility of dyeing is good, cylinder (batch) difference is less. In addition, the use of reactive dyes dyeing, if it is combination of color, it is best to choose a better compatibility of reactive dyes for collocation.
3. Postprocessing
Post-treatment is an important part of raw cotton dyeing, after dyeing should do fully washed and soaping treatment, in order to remove impurities and residual chemical additives on the cotton fiber. When washing, detergent with strong decontamination ability and good permeability should be used to enhance the cleaning effect of the inner layer of the fiber. After washing, in order to increase the spinnability, softening agent should be added for softening treatment to improve the lubricity of the fiber.
DEHYDRATOR AND DRYING
After dehydration , the color cotton treated by softener is easy to loose, after production practice, the moisture return after drying is controlled at 6 to 8, with soft feel and good spinnability.
SPINNING TECHNOLOGY
After raw cotton dyeing, the cotton fiber lost spinnability processing of boiled and bleached, removed wax and oil, feel becomes coarse. In order to improve this situation, one the one hand, adding softener to loosen the cotton and improve its spinnability after full washing. On the other hand, reasonable cotton matching with raw cotton. There are two kinds of cotton matching between colored cotton and raw cotton: One is carried out in the cotton cleaning process, the color cotton and the raw cotton after grabbing cotton, mixing cotton, opening into rolls and strips, finally spinning and knitted or woven fabric; Another one is processing during combining, the color sliver with the raw cotton sliver, through two strips, so that it is mixed into a strip, finally spinning and weaving or knitting. Through experiment, the former method is better, color cotton and raw cotton through mixing , carding, spinning and weaving, basically eliminate color difference.No matter which one is adopted, the mixing ratio of color cotton and raw cotton is generally controlled at about 0.5-10 percent, spinnability is better, don't change the original production technology.
DYEING INTANCE
9.7tex red cotton using Shin Tong Yunn high temperature high pressure dyeing machine, bath ratio 1:15, internal and external cycle time ratio 5:3.
1. Process flow: raw cotton- boiling-washing-dyeing-washing-soft treatment-dehydration-drying - packing
2. pretreatment
Process prescription, (g/L)NaOH(36 'Be) 5 stabilizer FT 2OH202(27.5%) 8, Temperature 120℃ penetrant JFc 1.0 time 120min.
3. Raw cotton dyeing (bright red) process prescription, (g/L) Peregal O 015 reactive brilliant orange X-Gn 3. 575N a2CO 3 25 Bright Red X一3B 6．i25Na2SO． 70。
4. Soft treatment
Process prescription, (g/L) softener HC-8
5. Dyeing cotton by spinning process
Cotton blending - roll - carding - strip - roving - fine yarn - raw cotton - fine cotton
NOTE:
DF241 series high pressure cone yarn dyeing machine is suitable doing pre-treatment, post processing and dyeing of raw cotton(cotton fiber), only need change the carrier form.