9 Misunderstandings in Reactive Dyes Dyeing Operation

1 Why is it required to use a small amount of cold water to mix the slurry first, and the temperature of the chemical should not be too high?

(1) The purpose of first mixing with a small amount of cold water is to make the dye easily and fully soaked. If the dye is directly poured into the water, the outer layer of the dye will form a gel, and the dye particles will be wrapped, so that the inside of the dye particles is difficult to get wet and difficult to dissolve. , so it should be mixed with a small amount of cold water first, and then melted with hot water.

(2) If the temperature of the chemical material is too high, it will cause the hydrolysis of the dye and reduce the dye fixation rate.

2 Why should it be slow and uniform when feeding?

This is mainly to prevent the dye from being dyed too fast. If the dye is added quickly at one time, the dyeing rate will be too fast, which will make the outer layer of the fiber dark, and the inner light will easily cause colored flowers or streaks.

3 Why do you need to add salt after dyeing for a certain period of time (eg 10min) after adding dye?

Salt is a dye-accelerating agent. When the dye is dyed to a certain extent, it has reached saturation and it is difficult to continue dyeing. Adding salt is to break this balance, but it takes about 10-15 minutes before adding salt to promote dyeing. Fully penetrate evenly, otherwise it is easy to cause striped flowers and colored flowers.

4 Why should the salt be added in stages?

The purpose of adding salt in stages is to promote the dye evenly, so as not to promote the dye too quickly and cause color flowers.

5 Why does it take a certain time (such as 20 minutes) to fix the color after adding salt.

There are two main reasons: 1) Let the salt dissolve evenly in the tank and fully promote the dyeing; 2) After the dye-promoting enters the dyeing saturation and reaches a balance, add alkali to fix the color to achieve the highest dyeing amount.

6 Why does adding alkali become "fixed color"?

The addition of salt to reactive dyes only has the effect of promoting dyeing, but adding alkali will stimulate the activity of reactive dyes, so that the dyes and fibers react (chemically) under alkaline conditions, so that the dyes are fixed on the fibers, so the term "fixation" is also due to This kind of fixation undergoes a chemical reaction to achieve higher fastness. Once the solid color is printed, it is difficult to be uniform.

7 Why should the alkali be added in stages?

The purpose of adding in batches is to make the color fixation uniform and prevent color blooming. If it is added at one time, it is easy to cause the local residual liquid concentration is too high and the fiber reaction is accelerated, which will easily cause color flowers.

8 Why must the steam be turned off first when feeding?

a. The purpose of turning off the steam before feeding is to reduce the stripe and prevent the color flower.

b. When the temperature of the control cylinder exceeds 3°C, the dyeing will be affected. If the temperature exceeds 5°C, streaks will appear, and if the temperature exceeds 10°C, the machine will be shut down for maintenance.

c. Some people have tested that the temperature in the tank is basically uniform before and after the steam for 10-15 minutes, and is equal to the surface temperature, so adding materials, whether adding H202 during chlorine cooking or adding dyes, salt, and soda ash during dyeing, all The steam should be turned off before feeding.

9 Why do you ensure the process holding time after adding alkali?

The heat preservation time should be calculated from the time of adding alkali and heating up to the process heat preservation temperature. Only by cutting the plate according to the process heat preservation time, the quality can be guaranteed, because the heat preservation time is determined according to how much time it takes for a certain amount of dye to react. The laboratory is also proofing at this time.