Views: 1000 Author: Site Editor Publish Time: 2022-04-20 Origin: Site
In recent years, customers have higher and higher requirements for the color depth of dark fabrics (especially reactive black, vulcanized black, and dispersed black), which also poses new challenges for printing and dyeing enterprises in production technology! At present, there are two main methods for the dyeing factory to deepen the deep color of the fabric: one is to cationically modify the surface of the fabric to make the cationic fibers and anionic dyes more adsorbable, and to improve the dye uptake and the rate of dyeing on the fabric. Fixing rate, so as to achieve the purpose of dyeing dark colors; the second is to use optical principles to change human vision to achieve the purpose of darkening the appearance of dyeing.
Deepening silicone oil RD is to cover the surface of the fabric with a layer of organic substances with low refractive index, which weakens the ability of the fabric to reflect and scatter light, and uses optical principles to change human vision. The method of use is simple (used in the setting machine slot), and the effect is obvious, especially the black products that are currently used in dyeing factories, which are widely used.
1.1.1 Cationic modification of fibers
Cationic modification is performed on the fabric to be treated, so as to change the electronegativity of the fabric surface and generate a stronger adsorption force between the fiber and the dye. The cationic modification of the fiber is to make the fiber cationic, and combine with anionic dyes. Firm, so as to achieve the purpose of improving the dyeing rate and color fixing rate and increasing the color depth.
Substances that can modify fibers can be divided into two categories: organometallic compounds and nitrogen-containing cationic compounds; one is multivalent metal salts, which have electrostatic attraction and complexation with fibers; the other is nitrogen-containing cationic compounds, which can interact with fibers. The reactive groups form covalent bonds.
1.1.2 Using optical principles to change human vision
After the fabric is treated, a layer of low refractive index film is formed on the surface of the fiber, which changes the absorption, reflection and refraction of light by the fiber, and uses optical principles to change human vision, so as to obtain the effect of darker color to the naked eye. Resins and silicones, darkening silicone oil RD is an environmentally friendly special siloxane compound, suitable for darkening and brightening finishing after dyeing with reactive dyes, disperse dyes, sulfur dyes, direct dyes, etc. or after washing clothes.
Without adding dyes, after the fabric is treated with deepening silicone oil, a layer of film will be formed on the surface of the fabric, and the reflection and absorption of light will change. In the human eye, the color of the fabric is perceived to have deepened. Using darkening silicone oil to treat dyed fabrics can not only deepen the color of dyed products, reduce the amount of dyes used, and reduce production costs, but also reduce the content of colored substances in sewage and reduce the pressure on dyeing factories to treat sewage. This article focuses on the market black fabrics (sulfurized black dyed cotton and dispersed black dyed polyester), and it is necessary and meaningful to use darkening silicone oil.
1.1.3 Deepening of cotton black and polyester black
There are many dyes that can dye cotton fibers, such as reactive dyes, sulfur dyes, Shihlin dyes, direct dyes, etc. For black dyeing, reactive black and sulfur black are mostly used, especially sulfur black. Color depth, especially environmentally friendly sulfur black is widely used. Sulfur black dye itself is insoluble in water. Under the action of strong reducing agent sulfide alkali, sulfur black can form sodium salt leuco and dissolve in aqueous solution. This leuco has strong directness to fibers. After oxidation, it becomes an insoluble substance again, and it is firmly fixed on the fiber.
The amount of alkali added in sulfur black dyeing should not be too large. The alkali can help dissolve the dye and soften the water quality, but if it is added too much, the dye will be dyed too fast, and it is easy to appear color flowers and white core defects.
In the production process of dyeing and finishing, the reduction and dissolution of sulfur dyes are required to be sufficient. After heating up to 95-98 °C for 20 minutes, slowly add Yuanming powder or salt to promote dyeing. After holding for a certain period of time, the temperature should not be too fast to avoid color flowers. , color spots, chicken paw prints and other defects, after the dye liquor is naturally cooled to 80 ℃, slowly add water, run the water close to the full tank for 10 minutes, and release the dye liquor 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. 20～50%), 85℃ for 10min, otherwise there will be quality problems such as colored flowers and erythema; It is sufficient to treat at 90°C for 20 minutes.
If white spots appear after dyeing, 0.5-1% sodium sulfite can be added to the dye solution, which can make the free sulfur floating on the surface of the dye solution easy to produce white spots to generate water-soluble sodium thiosulfate to be removed; make sulfur black after dyeing Anti-brittleness and softening treatment process (softener 3-7%, urea 1%, 40℃×10min) to avoid damage to the fabric during storage. For the fabrics that need to be repaired, it is recommended to use 1-2% soda ash, 15-20% alkali sulfide, 3-5% sulfide black, and 5% salt or Yuan Mingfen.
The above formula process is only for reference and cannot be dogmatic. The equipment and raw materials used in each factory are different, and the specifics can be adjusted according to the actual situation. In the production process, it is necessary to strictly abide by the operation regulations, implement the production process well, improve the success rate and reduce the repair rate.
After sulphur black dyeing, the cloth surface is jet black and the color is bright, but the customer's demand for product quality is getting higher and higher. Facing the new high requirements of customers, the dyeing factory can use darkening silicone oil for finishing, and the finished black cloth is visually , the color depth can be deepened by 30 to 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. fiber and other cellulose fibers), the refractive index and reflectivity are relatively large. When the light hits the surface of the polyester fabric, a large amount of incident light is reflected on the surface of the fabric, and only a part of the light is refracted into the fiber. This part of the light is colored light, giving People feel that the depth of the polyester color is not in place, and the chroma is shallow to the naked eye.
Especially the polyester fine denier fibers used in the market, because the surface area of the fibers is larger than that of ordinary polyester fibers, the reflected light is more, and the final color of the fabric is lighter; in order to improve the color depth, increase the quality and grade of the product, especially the most used in the market. Black, in order to obtain bright and jet-black fabrics, darkening silicone oil can be used for finishing, which can reduce the refractive index of the polyester fiber surface, making the fabric look darker and meeting the customer's requirements for color depth.
Deepening silicone oil has more profound significance for the deepening treatment of polyester fiber and polyester fine fiber, and the deepening silicone oil is easy to use and has good effect, which is worthy of application and promotion in dyeing factories.
During the production and use of deepening silicone oil, always pay attention to the pH value change of the shaping tank and whether the silicone oil is demulsification, so as to avoid the occurrence of difficult to handle silicone oil spots and silicone oil spots, which will affect product production and product quality.