What is the role of sodium sulfate?

As direct dyes and other accelerating agents for cotton dyeing

When dyeing cotton with direct dyes, sulphur dyes, vat dyes and Yindioxin dyes, sodium sulfate can be used as a dye-promoting agent.

These dyes are easy to dissolve in the prepared dyeing liquor, but not easy to dye cotton fibers. Because the dye is not easy to be exhausted, there is a lot of dye remaining in the foot water.

The addition of sodium sulfate can reduce the solubility of the dye in water, thereby increasing the coloring power of the dye. In this way, the amount of dye can be reduced, and the dyed color will be deepened.

1. The amount of sodium sulfate

It depends on the coloring power of the dyes used and the desired color depth. Don't add too much or too fast, otherwise the dye in the dyeing solution will precipitate and cause staining spots on the cloth surface.

2. When dyeing cotton fabric

Yuanming powder is generally added in batches in the 3rd to 4th steps. Because the dye solution is very thick before dyeing, if it is added quickly, the dye will dye on the fiber too quickly and it is easy to produce unevenness, so dye it for a while and then add it. Proper.

3. Sodium sulfate before use

Yuanming powder should be fully deepened with water before use, and filtered before being added to the dyeing bath. It is more necessary to stir the dyeing bath and slowly add it to prevent the partial dyeing bath from contacting a large amount of accelerant and causing the dye to salt. Analyze role.

4. Sodium sulfate and salt are commonly used dye accelerators

Practice has proved that in direct dyeing, using sodium sulfate as a dye accelerator can get a bright color. The effect of using table salt is poor, which is related to the purity of table salt. In addition to more calcium and magnesium ions, general industrial salt also contains iron ions. Some dyes that are greatly affected by iron ions (such as direct turquoise blue GL, etc.) use salt as a dye accelerant, which will cause the color to be gray.

5. Some people think that the price of table salt is cheaper

Some people think that the price of table salt is cheaper, and table salt can be used to replace Yuanming powder. However, it is better to use Yuanming powder for light color than table salt, and for dark color, table salt is better. Whatever is appropriate, it must be applied after testing.

6. The relationship between sodium sulfate and the amount of salt

The relationship between sodium sulfate and salt consumption is roughly as follows:

6 parts anhydrous Na2SO4=5 parts NaCl

12 parts hydrate Na2SO4·10H20=5 parts NaCl

Used as a retarder for direct dyeing and silk dyeing

The application of direct dyes on protein fibers is mostly silk dyeing, and the dyeing fastness obtained is better than that of general acid dyes. Some direct dyes also have excellent dischargeability, so they are often used for discharge of ground color in silk fabric printing.

Direct dyeing of silk also often adds a small amount of sodium sulfate, but the role of sodium sulfate is different from that of cotton dyeing. It only acts as a slow dyeing agent.

As acid dye retarder

When acid dyes are used to dye silk, wool and other animal fibers, sulfuric acid and acetic acid are often added to promote the coloring of the pigment acid, but at the same time, the powder is also used as a dye retardant.

Used as ground color protectant for scouring of printed and dyed silk fabrics

When scouring printing or dyeing silk fabrics, the dye may be peeled off, so that it will stain the ground color or other synchronized fabrics. If sodium sulfate is added, the solubility of the dye can be reduced, so there is no danger of peeling off the dye and contaminating the ground color. Up.