What are the characteristics of substitute alkali?

1. When dyeing cellulose fibers with reactive dyes, it needs to be fixed under alkaline conditions. Currently, the reactive dyes used in dispersal dyeing are mostly medium-temperature heterobiactive reactive dyes. This type of dyes have a wide range of fixation temperature and fixation pH. Perspiration fastness, light fastness and wet rubbing fastness and other indicators are better and are widely used.

2. Double reactive dyes are generally fixed with soda ash or trisodium phosphate. At this stage, due to the impact of environmental protection requirements, sodium phosphate is rarely used, so most of them are soda ash.

3. The advantages of soda ash are moderate alkalinity, good buffering, good color reproducibility, and it is used in low, medium and high temperature reactive dyeing. The disadvantage is that the dosage is large, the operation is troublesome, and it is easy to generate dust.

4. Substitute alkali is a kind of mixed alkali composed of a variety of alkali agents and buffers. It can reach the pH of soda ash fixation in a small amount. The biggest advantage of using substitute alkali is to reduce labor and save costs.

Substitute alkali to replace soda ash, in addition to providing the pH that meets the needs of color fixation, it should also have the following points: good dye depth, small changes in shade, good brightness, and no decrease in fastness.

1) The color depth of soda ash dyeing can be completely achieved by using the substitute alkali as the alkali agent.

2) When the amount of substitute alkali is too large, the color depth will decrease instead, which is because the hydrolysis rate of reactive dyes increases faster when the amount of alkali agent increases.

3) The corresponding relationship between substitute alkali and soda ash should be between 1:8 and 1:10.

4) In the production application, the factory will adjust the pH value of the dye bath according to the actual production needs, according to the ratio of 1:10 substitute alkali, and add 2g/l soda ash to increase the depth of coloring.