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Details Of Disperse Dyes

Date:Oct 17, 2020

When dyeing, it must disperse the dye evenly in the dyeing solution with the aid of dispersant, so as to dye polyester and other fibers. 


The main purpose of disperse dyes is to dye polyester (polyester), acetate (diacetate, triacetate) and polyamide (polyamide) fibers in chemical fibers, as well as polyacrylonitrile (Pan). 


The chemical fiber textile products processed by disperse dyes have bright color, good washing fastness and wide application. 


Because it is insoluble in water, it has no dyeing ability to cotton, hemp, wool and silk in natural fibers, and almost does not stain viscose fiber. 


Therefore, chemical fiber blended products usually need to use disperse dyes and other applicable dyes.


Structure

Disperse dyes have small molecules and no water-soluble groups in the structure. With the help of dispersant, they disperse uniformly in the dyeing solution. 


The polyester / cotton dyed with disperse dyes can dye polyester fiber, acetate fiber and polyamide fiber and become the special dye for polyester fiber.


Disperse dyes can be roughly divided into disperse orange, disperse blue, disperse yellow and disperse red. Disperse dyes such as disperse black, disperse green and disperse violet can be obtained by mixing several different disperse dyes in a certain proportion.


In the process of commodity dyeing, disperse dyes disperse rapidly into uniform colloid suspension in order to disperse commercial dyes. 


The fineness of dye particles must reach 1 microns. In addition, dispersants and wetting agents are added to the process of grinding. The postprocessing of disperse dyes is usually made up of sand, seasoning, spray drying and packaging.


 In the post-processing process, many additives are used, such as lignin, MF, anti settling agent (SOS), dustproof agent, dispersant NNO, and Canadian powder for strength adjustment.


Disperse dyes are the most important and main category in the dye industry. They do not contain strong water-soluble groups and disperse in the dyeing process.


 The particle size should be about 1 μ M. After the original dyes are prepared, commercial dyes can be prepared by post-processing, including stable crystal form and grinding with dispersant. It is mainly used for printing and dyeing of polyester and its blended fabrics. 


It can also be used for printing and dyeing of synthetic fibers such as acetate fiber, polyamide fiber, polypropylene fiber, chlorine fiber and acrylic fiber.



History

A kind of dye which is slightly soluble in water and highly dispersed in water by the action of dispersant. 


Disperse dyes do not contain water-soluble groups and have low molecular weight. Although molecular disperse dyes contain polar groups (such as hydroxyl group, amino group, hydroxyalkamido group, cyanoamino group, etc.), they are still nonionic dyes. This kind of dyestuff requires high post-treatment, which usually needs to be grinded by a grinder in the presence of dispersant to form highly dispersed and stable crystalline particles. 


The dyeing solution of disperse dyes is a uniform and stable suspension. Disperse dyes were produced in 1922 by Baden aniline soda company of Germany. 


They are mainly used for dyeing polyester fiber and acetate fiber. At that time, it was mainly used for dyeing acetate fiber. After the 1950s, with the emergence of polyester fiber, it has obtained rapid development and become a large category of products in the dye industry.


 Classification disperse dyes (see table) can be divided into azo type, anthraquinone type and heterocyclic type according to their molecular structure. They are named according to certain principles (see dyes) and numbered according to the dye index (C.I.). ① The chromatogram of azo type is more complete than reagent, with yellow, orange, red, purple, blue and other colors. Azo disperse dyes can be produced by the general synthetic method of azo dyes. The process is simple and the cost is low. ② Anthraquinone type has red, purple, blue and other colors. ③ Heterocyclic dyes are a kind of newly developed dyes with bright color. The production process of anthraquinone and heterocyclic disperse dyes is complex and the cost is high.



Classification

Disperse dyes can be divided into low temperature type, medium temperature type and high temperature type according to their heat resistance.


Low temperature dyes

It has low sublimation fastness and good levelness. It is suitable for exhaustion dyeing and is often called E-type dye;


High temperature dyes

High sublimation fastness, but poor levelness, suitable for hot melt dyeing, known as S-type dyes;


Medium temperature dyes

Sublimation fastness between the above two, also known as Se type dyes.

When polyester is dyed with disperse dyes, dyes should be selected according to different dyeing methods.


Nature

Disperse dyes have simple structure and are in non-ionic state with very low solubility in water. In order to disperse the dyes well in the solution, in addition to grinding the dye particles to less than 2 μ m, a large amount of dispersant should be added to make the dyes disperse stably in the solution as a suspension.