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Introduction to Dyes Used for Dyeing Cotton Fabrics(Part 2)

Pulished on Nov. 09, 2020

4. Soluble vat dyes are derivatives of vat dyes, which are soluble in water. After dyeing on the fiber, they need to be oxidized in acid solution to hydrolyze and oxidize the dyes and return to insoluble vat dyes on the fiber. The dyeing process of soluble vat dyes is relatively simple, the dyeing is relatively even and the dyeing fastness is high. However, this dye is expensive and is mainly used for dyeing and printing light and medium-colored cotton fabrics.

5. Sulfur dyes are insoluble in water but can be dissolved in sodium sulfide solution and reduced to leuco body. After the leuco body is absorbed by cotton fiber, it is oxidized to insoluble dye and fixed on the cotton fiber. Sulfur dyes are mainly used for dyeing cotton fiber dark products. Washing and sun exposure is good. The dyeing method is simple and cheap, but its colorfastness to friction is poor and the color is not bright enough. Certain dyes (such as sulfur black) will make the fiber brittle during the storage of the fabric, so it needs to be treated with embrittlement prevention after dyeing. Yellow and orange sulfur dyes often have photosensitive and brittle effects on fibers.

Cotton Muslin Fabric

6. Insoluble azo dyes are composed of a primer (color phenol) and a developer (color base) between two dyes. When dyeing, the fabric is first made with naphthol's caustic soda solution, and then the color base's diazotization solution is used to develop the color. The naphthol and the color base are diazo compound on the fabric couple with melon to form insoluble azo dyes, which are fixed on the fabric on. Since ice is needed for the diazotization reaction of the color base, the insoluble azo dye is also called ice dye. This kind of dyes have bright color, good soaping fastness, and good light fastness, but the color fastness to rubbing is poor, and the fastness to wet rubbing is worse.

7. Stable insoluble azo dyes are a mixture of naphthol sodium salt and a temporarily stable diazo compound. Under normal circumstances, the two do not undergo a coupling reaction. After printing, after a certain treatment, the temporarily stable diazo compound is transformed into an active diazo compound, and it is coupled with naphthol to form a non-deep azo dye. This type of dye is mainly used to print small patterns.

The above information is provided by cotton printed fabric factory.