Soluble vat dye
Time:
2023/02/27
4. Soluble vat dyes Soluble vat dyes are derivatives of vat dyes that are soluble in water. After dyeing on the fiber, they need to undergo oxidation treatment in the acid solution to hydrolyze and oxidize the dye, and then revert to insoluble vat dyes for dyeing on the fiber. The dyeing process of soluble vat dyes is relatively simple, the dyeing is relatively uniform and the dyeing fastness is high. However, this kind of dye is expensive and mainly used for dyeing and printing of light and medium color cotton fabrics.
5. Sulfide dyes Sulfide dyes are insoluble in water, but can be dissolved in sodium sulfide solution and reduced to cryptochrome. After being absorbed by cotton fiber, cryptochrome is oxidized to insoluble dyes and fixed on cotton fiber. Sulfide dyes are mainly used for the dyeing of cotton fiber dark products, with good washing and sun exposure, simple dyeing method and cheap price, but their color fastness to rubbing is poor and the color is not bright enough. Some dyes (such as sulfur black) will cause fiber embrittlement during fabric storage, so anti-embrittlement treatment is required after dyeing. Yellow and orange sulfide dyes often have photosensitive embrittlement effect on fibers.
6. Insoluble azo dyes Insoluble azo dyes are composed of two upper dyes with a middle primer (naphthol) and a chromogenic agent (color base). When dyeing, the fabric is first primed with naphthol's caustic soda solution, and then colored with the color base's diazo solution. The naphthol on the fabric and the color base's diazo compound are coupled to form insoluble azo dyes, which are fixed on the fabric. Because ice is needed for diazotization reaction of color base, insoluble azo dyes are also called ice dyes. This kind of dye has bright color, good color fastness to soaping, good color fastness to sunlight, but poor color fastness to rubbing, and worse color fastness to wet rubbing.
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