Views: 0 Author: Site Editor Publish Time: 2024-01-19 Origin: Site
1.3 Cotton black and polyester black deepening
There are many dyes that can dye cotton fibers, such as reactive dyes, sulfur dyes, Shilin dyes, direct dyes, etc. Most of the black dyes are reactive black and sulfur black, especially sulfur black. Compared with reactive black, it has better fastness and better Deep color, especially environmentally friendly sulfur black is currently widely used. The sulfur black dye itself is insoluble in water. Under the action of the strong reducing agent sulfide alkali, the sulfur black can form a sodium salt leuco body and dissolve in the aqueous solution. This leuco body has strong directness to the fiber. After dyeing, the sulfur black dye itself is insoluble in water. After oxidation, it becomes an insoluble substance again and is firmly fixed on the fiber.
When dyeing with sulfur black, the amount of alkali added should not be too large. Alkali can help dissolve the dye and soften the water quality. However, if too much is added, the dye will be dyed too quickly, and color flowers and white core defects will easily appear.
During the dyeing and finishing production process, it is required that the sulfur dyes are fully reduced and dissolved. After the temperature is raised to 95-98°C for 20 minutes, Yuanming powder or salt is slowly added to promote dyeing. After being kept warm for a certain period of time, the temperature should not be cooled too fast to avoid color blooms. , color spots, chicken paw prints and other defects, after the dye solution naturally cools down to 80°C, slowly add clean water, drain the water and run it for 10 minutes until the tank is nearly full, and then drain the dye solution after dyeing.
During the dyeing process of sulfur black, the color of the leuco body in the dye bath should be checked frequently. The color of the leuco body before and after dyeing should be basically the same. If there is a difference, sulfide alkali (amount of the total amount of sulfide alkali during dyeing) can be added before terminating the dyeing. 20~50%), treat at 85℃ for 10 minutes, otherwise quality problems such as color flowers and erythema will occur; for defects such as erythema and red streaks that have appeared after dyeing, (5~10g/l) alkali sulfide solution can be used, 85~ Process at 90°C for 20 minutes.
If white spots appear after dyeing, 0.5 to 1% sodium sulfite can be added to the dye solution, which can cause the free sulfur floating on the surface of the dye solution that is prone to white spots to generate water-soluble sodium thiosulfate and be removed; make sulfide black after dyeing Anti-brittle and softening treatment process (softener 3~7%, urea 1%, 40℃×10min) to avoid damage to the fabric during storage. For cloth with colored patterns that need to be repaired, it is recommended to use 1 to 2% soda ash, 15 to 20% alkali sulfide, 3 to 5% sulfide black, and 5% salt or Yuanming powder.
The above formula process is for reference only and cannot be dogmatic. The equipment and raw materials used in each factory are different, and the details can be adjusted according to the actual situation. During the production process, it is necessary to strictly abide by the operating regulations, implement the production process well, improve the success rate, and reduce the repair rate.
After dyeing with sulfur black, the cloth surface will be dark and bright. However, customers have increasingly higher demands for product quality. Faced with new high demands from customers, dyeing factories can use darkening silicone oil for finishing. The finished black fabric will look visually , the color depth can be deepened by 30~50%
In the fabric market, polyester fiber is widely used in clothing and other industrial fields due to its excellent dimensional stability, resilience, and wear resistance. Its usage is increasing and its proportion is relatively large. The surface of polyester fiber is smooth (compared to cotton). fiber and other cellulose fibers), the refractive index and reflectivity are relatively large. When light shines on the surface of polyester fabric, a large amount of incident light is reflected on the surface of the fabric, and only part of the light is refracted into the fiber. This part of the light is colored light, giving People feel that the color depth of polyester is not enough, and the color looks lighter to the naked eye.
Especially the polyester fine-denier fiber used in the market, because the fiber surface area is larger than that of ordinary polyester fiber, it reflects more light, and finally the color of the fabric is lighter; in order to improve the color depth and increase product quality and grade, especially the most used polyester fiber on the market Black, in order to obtain bright and dark fabrics, darkening silicone oil can be used for finishing. Darkening silicone oil can reduce the refractive index of the polyester fiber surface, making the color of the fabric appear darker, meeting the customer's requirements for color depth.
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