Dyes Are Classified According To Their Properties And Application Methods

Dyes can be classified as follows according to their properties and application methods:

l. Direct dyes dyestuff It is named because it can be directly dyed on cotton, linen, silk, wool and other fibers without relying on other agents.

2. Reactive dyes are also called reactive dyes. Its molecular structure contains one or more active genes. Under appropriate conditions, it can react with fibers to form covalent bonds.

3. The vat dyes are insoluble in water. They are dyed in strong alkaline solution with the help of reductant reduction and dissolution. After dyeing, they are oxidized and re converted into insoluble dyes and firmly fixed on the fibers.

4. Most of these dyes are insoluble in water and organic solvents, but can be dissolved in alkali sulfide solution, which can directly dye fibers. However, the dye solution is too alkaline to dye protein fibers.

5. Sulfide vat dyes The chemical structure and manufacturing method of sulfur vat dyes are the same as those of common sulfur dyes, but their dyeing fastness and dyeing performance are between those of sulfur and vat dyes, so they are called sulfur vat dyes. When dyeing, the dyes can be dissolved by caustic soda sodium hydrosulfite or sodium sulfite sodium hydrosulfite.

6. Oxidized dyes Some aromatic amine compounds fibre When complex oxidation and condensation reactions are carried out, they become insoluble dyes, called oxidized dyes.

7. Disperse dyes are non-ionic dyes with low solubility in water and fine particles, which are dispersed in the dye solution. They are mainly used for the dyeing of polyester fibers and have high dyeing fastness.

8. Dyes such as acid dyes are water-soluble, and most of them contain water-soluble genes such as sulfonic group and carboxyl group. It can dye protein fiber directly in acid, weak acid or neutral medium, but its wet treatment fastness is poor.

9. Basic and cationic dyes Basic dyes were called base dyes in the early days, which were the first kind of dyes synthesized. They are also called cationic dyes because they have a positive charge after being dissolved in water.

At present, there are more than 7000 kinds of dyes produced in the world, and more than 2000 kinds are commonly used. Due to the different structures, types and properties of dyes, dyes must be selected according to the requirements of dyeing products to determine the corresponding dyeing process conditions.

Nomenclature of dyes

In China, three paragraph naming method is used for the naming of dyes. The names of dyes are divided into three parts, namely, crown, color and endnote.

1. Crown name mainly refers to the names of dyes classified according to their application methods or properties, such as dispersion, reduction, activity, direct, etc.

2. Color scale means to use this dye to Textile The names of colors that can be obtained after dyeing are generally expressed in the following four ways

(1) Physical common names, such as red, green, blue, etc.

(2) Use plant names, such as orange, peach, grass green, rose, etc.

(3) Represented by natural phenomena, such as blue sky, golden yellow, etc.

(4) It is expressed by animal name, such as mouse grey, goose yellow, etc.

3. Endnotes indicate the shade, performance, state, concentration of dyes, and applicable fabrics, which are usually represented by letters and numbers.