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Basic knowledge of dyes: disperse dyes

Views: 55     Author: Site Editor     Publish Time: 2021-05-12      Origin: Site Inquire

Disperse dyes are a very important and main category in the dye industry. They do not contain strong water-soluble groups and are a class of non-ionic dyes that are dyed in a dispersed state during the dyeing process. Mainly used for printing and dyeing polyester and its blended fabrics. It can also be used for the printing and dyeing of synthetic fibers such as acetate, nylon, polypropylene, chlorinated and acrylic.

Overview of disperse dyes


Disperse dye, a kind of dye that is slightly soluble in water and is highly dispersed in water by the action of a dispersant. Disperse dyes do not contain water-soluble groups and have a low molecular weight. Although they contain polar groups (such as hydroxyl, amino, hydroxyalkylamino, cyanoalkylamino, etc.), they are still nonionic dyes. Such dyes require high post-treatment, and usually need to be ground by a grinder in the presence of a dispersant to become highly dispersed and stable crystal particles before they can be used. The dye liquor of disperse dyes is a uniform and stable suspension.


2. History:

Disperse dyes were produced by the Baden Aniline Soda Company in Germany in 1922 and are mainly used for dyeing polyester fibers and acetate fibers. At that time, it was mainly used for dyeing acetate fibers. After the 1950s, with the emergence of polyester fiber, it developed rapidly and became a major product in the dye industry.

Classification of Disperse Dyes

1. Classified by molecular structure:

According to the molecular structure, it can be divided into three types: azo type, anthraquinone type and heterocyclic type.

The azo-type chromatogram is complete, with various colors such as yellow, orange, red, purple, and blue. Azo-type disperse dyes can be produced according to general azo dye synthesis methods, with simple process and low cost. (Accounting for about 75% of disperse dyes)

The anthraquinone type has colors such as red, purple, and blue. (Accounting for about 20% of disperse dyes) Anthraquinone dyes, a dye race known for their bright colors.

Heterocyclic dyes are a newly developed type of dyes with bright colors. (Heterocyclic type accounts for about 5% of disperse dyes)

The production process of anthraquinone-type and heterocyclic-type disperse dyes is more complicated and costly.

2. According to the heat resistance of the application:

Can be divided into low temperature type, medium temperature type and high temperature type.

Low-temperature dyes have low sublimation fastness and good levelling performance. They are suitable for exhaustion dyeing and are often called E-type dyes. High-temperature dyes have high sublimation fastness, but have poor leveling properties and are suitable for hot melt dyeing. , Called S-type dye; medium-temperature dye, sublimation fastness is between the above two, also known as SE-type dye.


Terms related to disperse dyes

1. Color fastness:

The color of textiles is resistant to various physical, chemical, and biochemical effects during the dyeing and finishing process, use or taking.

2. Standard depth:

The recognized depth standard series defines medium depth as 1/1 standard depth. The colors of the same standard depth are equal in psychological sense, so that the color fastness can be compared on the same basis. At present, it has developed to six standard depths of 2/1, 1/1, 1/3, 1/6, 1/12, and 1/25.

3. Dyeing depth:

Expressed as the percentage of dye weight to fiber weight, the dye concentration varies according to different colors. Generally, the dyeing depth is 1%, the dyeing depth of navy blue is 2%, and the dyeing depth of black is 4%.

4. Discoloration:

After a certain treatment, the color of the dyed fabric changes in shade, depth or brilliance, or the combined result of these changes.

5. Staining:

After a certain treatment, the color of the dyed fabric transfers to the adjacent lining fabric, contaminating the lining fabric.

6. Gray sample card for evaluating discoloration:

In the color fastness test, the standard gray sample card used to assess the degree of discoloration of the dyed material is generally called the color change sample card.

7. Gray sample card for staining evaluation:

In the color fastness test, the standard gray sample card used to evaluate the staining degree of the dyed material to the lining fabric is generally called the staining sample card.

8. Color fastness rating:

According to the color fastness test, the degree of discoloration of the dyed fabric and the degree of staining of the lining fabric, the color fastness properties of the textiles are rated. Except for the eight-level light fastness (except AATCC standard light fastness), the rest is a five-level system. The higher the number, the better the fastness.

9. Adhesive fabric:

In the color fastness test, to determine the degree of staining of the dyed fabric to other fibers, it is an undyed white fabric that is treated together with the dyed fabric.


Common color fastness of disperse dyes

1. Color fastness to light:

The color of textiles is resistant to artificial light.

2. Color fastness to washing:

The color of the textile is resistant to washing under different conditions.

3. Color fastness to rubbing:

The color resistance of textiles to rubbing can be divided into dry and wet rubbing fastness.

4. Color fastness to sublimation:

The degree to which the color of textiles resists heat and sublimates.

5. Color fastness to perspiration:

The color resistance of textiles to human sweat can be divided into acid and alkali perspiration fastness according to the acidity and alkalinity of the test sweat.

6. Fastness to smoke fading:

The color of the textile resists the ability of nitrogen and oxygen compounds in the flue gas. Among the disperse dyes, especially those with an anthraquinone structure, when encountering nitric oxide and nitrogen dioxide, the dye will change color.

7. Color fastness to heat pressure:

The color of the textile resists ironing and roller processing.

8. Color fastness to dry heat:

The color of textiles can resist dry heat treatment.

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