Chemical preparation methods of various dyes



1. Direct dyes: The heat resistance and stability of direct dyes are relatively good. Soda ash and soft water can be added to help dissolve direct dyes. When converting materials, …

1. Direct dyes:

The heat resistance and stability of direct dyes are relatively good. Soda ash and soft water can be added to help dissolve direct dyes. When converting materials, use cold soft water to dissolve the dyes first. Make it into a slurry, boil it with soft water, stir and dissolve, dilute with heated water, add water to the specified liquid volume after cooling.

2. Reactive dyes:

This type of dye is not heat-resistant and is easily hydrolyzed at high temperatures. It is best to use cold soft water to make a slurry. Then use soft water of a suitable temperature to dissolve the dye according to the hydrolysis stability of different dyes. Heat the soft water to dilute it. After cooling, add soft water to the specified liquid volume.

Low temperature type (X type): use cold water or 30-35℃ warm water (already basically eliminated)

High temperature type (K Type, HE type, etc.) use 70-80℃ hot water

Medium temperature type (KN, M type) use 60-70℃ hot water

For low solubility, use 90 ℃ hot water

3. Vat dyes:

The dissolution process of vat dye is a reduction reaction process. When dissolving, the dissolution temperature must be determined according to the reducing conditions of the reducing agent used. For example, the commonly used reducing agent for vat dyes is insurance powder. The optimal use temperature in the solution is 60°C. Excessive temperature will cause a large amount of insurance powder to decompose.

(1) Full bath method:

Put the dye into the dyeing cup, add red oil and a small amount of warm soft water and mix thoroughly, then add the specified amount of caustic soda and Powder, add soft water to the required bath volume, and restore at 55°C.

(2) Dry cylinder method:

Put the dye into the dyeing cup, add red oil and a small amount of warm soft water and mix thoroughly, then Add two-thirds of the amount of caustic soda and insurance powder, so that the amount of dye solution is one-third of the total amount. The dissolution temperature should be determined according to the reducing conditions of the reducing agent used. Add the remaining caustic soda and insurance powder to the dye cup, and add soft water to the required bath volume.

4. Sulfur dyes:

Accurately weigh the required amount of dye into a beaker, mix it into a slurry with cold soft water, then add the pre-dissolved sodium sulfide dye solution and boil for 10 minutes. Heat soft water to dilute, add soft water to the specified liquid volume after cooling.

5. Disperse dyes:

If the temperature is too high, disperse dyes tend to crystallize and precipitate. When mixing the material, it is advisable to use cold soft water to mix the slurry first, then use cold soft water below 40°C to mix the material, and add soft water to the specified liquid volume.

6. Acid dyes:

Acid dyes have relatively good heat resistance and stability. When converting acid dyes into materials, first use cold soft water to make the dye into a slurry, then boil the soft water and stir to dissolve, heat the soft water to dilute, and after cooling, add soft water to the specified liquid volume.

7. Cationic dyes:

Cationic dyes have relatively good heat resistance and stability. When mixing the dye, first use concentrated acetic acid (solvent) to make the dye into a slurry, then boil soft water and stir to dissolve, dilute with heated water, and add soft water to the specified liquid volume after cooling. </p

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Author: clsrich

 
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