1. Foreword
In order to fully improve the added value of yarn-dyed fabrics, in addition to adding colors and patterns In addition to the style, high-count yarns, blended yarns and special dyeing processes can also be used to achieve unique dyed fabric styles. Pure cotton blended yarn-dyed fabric, soft to the touch, breathable and highly absorbent. In recent years, it has been favored by consumers. Colored cotton can be produced through blending, carding, spinning, and weaving to eliminate color differences and facilitate production.
2. Requirements for raw materials
1. Requirements for raw cotton
After the raw cotton is dyed, the colored cotton needs to be blended, carded, spun, and finally woven. The requirements for color difference are not high, so it is suitable for any variety of raw cotton.
2. Dyeing materials
The dyeing materials and auxiliaries used for raw cotton bleaching and dyeing are required to be chemical raw materials with fine particles, soluble in water, and good diffusibility and permeability.
3. Dyeing
In order to obtain better quality for cotton fabrics For the mixed color effect, two important issues should be paid attention to when dyeing raw cotton: the removal of natural impurities in loose fibers and the spinnability of dyed colored cotton.
1. Pre-treatment
Cotton fiber contains many symbiotic organisms, such as waxy matter, nitrogenous matter, and pectin matter , minerals and natural pigments, cotton seed hulls, etc. The existence of these symbiotic organisms will seriously affect the wetting performance of cotton fibers and make subsequent dyeing difficult, so they must be removed first. The pre-treatment of raw cotton dyeing is boiling, bleaching and related washing of raw cotton. The purpose is to remove cotton impurities, pectin and natural pigments on the raw cotton that hinder dyeing. After boiling, bleaching and sufficient water washing, check whether the alkali concentration, residual hydrogen peroxide and whiteness meet the process requirements. Under normal circumstances, the whiteness of pre-treated cotton fibers should be consistent and the pH value should be neutral.
2. Dyeing
Raw cotton can be dyed with direct dyes and reactive dyes, in terms of color fastness and ease of use. Considering that it is better to use reactive dyes for dyeing, because reactive dyes have bright colors, complete chromatograms and a certain degree of wet processing fastness. As long as the process is properly controlled and the additives are appropriately selected, the reproducibility of the dyeing will be good and the vat (batch) difference will be small. . In addition, choose reactive dyes for dyeing. If it is color matching, it is best to use reactive dyes with good compatibility for dyeing.
3. Post-processing
Post-processing is an important part of raw cotton dyeing. After dyeing, raw cotton must be fully washed and soaped. Treatment to remove impurities and residual chemical additives on cotton fibers. When washing, detergents with strong decontamination capabilities and good penetrating properties should be used to enhance the cleaning effect on the inner layer of the fiber. After washing, in order to increase the spinnability, softener should be added for softening treatment to improve the lubricity of the fiber.
4. Dehydration and drying
After dehydration, soften The colored cotton treated with the agent is easy to loosen. After production practice, the moisture regain after drying is controlled at 6-8. It feels soft and has good spinnability.
5. Spinning Technology
After the raw cotton is dyed, the cotton fiber is scoured, bleached and dyed. The wax and grease on the fabric are removed, the hand feels thicker, and the spinnability is lost. In order to improve this situation, on the one hand, after the dyeing is fully washed, a softener is added to loosen the cotton and improve its spinnability; on the other hand, it is reasonably matched with raw cotton. There are two types of blending of colored cotton and raw cotton; one is carried out in the cotton cleaning process, where the colored cotton and raw cotton are picked, mixed, and opened into rolls and strips, and finally spun and weaved; the other is In the drawing process, the colored cotton slivers are matched with the original cotton slivers, and then drawn through two passes to mix them into strips, and finally spun and weaved. Through experimental comparison, the former method is better. The color difference between colored cotton and raw cotton is basically eliminated through blending, carding, spinning and weaving. However, no matter which method is used, the mixing ratio of colored cotton and raw cotton is generally controlled at 0. About 5 to 10%, the spinnability is good, and there is no need to change the original production process.
6. Dyeing Examples
Variety: 9.7tex Dahong raw cotton is used Hong Kong Lixin high-temperature and high-pressure dyeing machine has a liquor ratio of 1:15 and an internal and external cycle time ratio of 5:3.
Processing process
Cotton preparation – scouring – washing – dyeing – washing – softening – dehydration – drying – bales 2. Pre-treatment
7. Conclusion
1. Colored cotton treated with softener is easy to loosen , the drying moisture regain is controlled at 6-8, the hand feel is soft, the spinning neps are greatly reduced, and the spinnability is significantly improved.
2. Raw cotton can be dyed with direct dyes and acid dyes.
3. The dyeing of raw cotton does not have high requirements for color difference. The color cotton is mixed, carded and spun to eliminate the color difference.
4. It can be spun from colored cotton or blended with raw cotton. Generally, the blending ratio is 0.5-10%. </p
