What are the requirements for the base of dyes?

The reaction rate of dye and fiber depends not only on the size of the reaction of the dye, but also on the strength of the alkali agent. Different types of dyes use different alkali agents. Pushan MX dyes and domestic X dyes are fixed with soda ash and baking soda. If caustic soda is used for color fixing, the dyes will be hydrolyzed seriously; Remazol, Ciba clone F, Dai cotton resin R/K and domestic K type, KN Type and ME type dyes should be mixed with caustic soda and sodium silicate (water glass) to fix the color.

(1) Sodium silicate acts as a buffer to adjust the pH value of the lye solution, which can control the hydrolysis reaction of dyes, which is beneficial to improve the color fixing rate; when rolling, the "alkali absorption" of the fabric is greatly reduced, and the pH value tends to be Stable and avoid chromatic aberration.

(2) As an adsorbent, sodium silicate has emulsifying and colloidal protective properties. During rolling and stacking, it can protect the fabric from being eroded by acid gas and carbon dioxide in the air; it can be hydrolyzed into colloidal silicic acid in the post-washing process. Or fine particle alkaline earth silicate, which has better adsorption and hydrolysis reactive dyes and prevents stains on fabrics.

(3) If vinyl sulfone type reactive dye is used, according to the improvement plan of sodium silicate, find out the required amount of caustic soda from the dye materials. Alkali agents for cold rolling piles include pure caustic soda method, soda ash + caustic soda method, caustic soda + trisodium phosphate method, caustic soda + water glass method.

Pure caustic soda method, even if the color fixing rate of the sample is high, the storage time of the mixture is very short, and the hydrolysis is very obvious after 10min. In the caustic soda + water glass method, the color fixing rate is lower among the four alkali agents, and the shallow edge phenomenon of this method is better. This is that water glass can effectively prevent the influence of CO2 and SO2 gas in the air on the selvedge; but the caustic soda + water glass method is difficult to wash, and the machine equipment is easy to scale. In addition, the finished cloth feels hard.

Relatively speaking, the caustic soda + soda ash method and the caustic soda + trisodium phosphate method are all better, because the soda ash and trisodium phosphate are secondary ionization and tertiary ionization respectively when releasing hydroxide. Therefore, after mixing with caustic soda, it has a certain buffering effect on the pH value, and the stability of the dye liquor is relatively good. These two mixed alkali agents are ideal, but considering the impact of trisodium phosphate on the environment, the caustic soda + soda ash method is recommended.