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10 mistakes often made with reactive dyes!

Views: 50     Author: Site Editor     Publish Time: 2021-07-16      Origin: Site


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1. Why is it required to use a small amount of cold water to adjust the slurry and the temperature of the compound should not be too high?

(1) Use a small amount of cold water to adjust the slurry first. The purpose is to make the dye easy to fully wet out. If you pour the dye directly into the water, the outer layer of the dye will form a gel, and the dye particles will be wrapped to make the inside of the dye particles difficult to wet , So you should mix a small amount of cold water first, and then use hot water to melt.

(2) If the temperature of the chemical compound 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 dyeing 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 deep, and the light inside will easily cause colored flowers or streaks.

3. Why do we need to dye for a certain period of time (such as: 10min) after adding the dye before adding salt?

Salt is a dye accelerant. When the dye is dyed to a certain level, it has reached saturation and it is difficult to continue dyeing. Salt is added 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 streaks and color blurs.

4. Why do you need to add salt in batches?

The purpose of adding salt in batches is to evenly promote the dyeing, so as not to promote the dyeing too quickly and cause color blur.

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

There are two main reasons: A. Let the salt dissolve evenly in the tank and fully promote the dye. B. After the dye is saturated and reach equilibrium, alkali is added to fix the dye to achieve the highest dye uptake.

6. Why does alkali add become "fixed color"?

Adding salt to reactive dyes can only promote dyeing, but adding alkali will stimulate the activity of reactive dyes, causing the dye to react with the fiber under alkaline conditions (chemical reaction) to fix the dye on the fiber, so it is called "fixing" because This kind of fixation undergoes a chemical reaction to achieve a higher fastness. Once the color is fixed, it is difficult to print evenly.


7. Why do we need to add alkali in batches?

The purpose of adding in batches is to make the fixation uniform and prevent color blur.

If it is added at one time, it is easy to cause the local residual liquid to be too high in concentration and the fiber will react quickly, which will easily cause color blur.

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 color blur.

b. When the temperature of the control cylinder is increased, the temperature on both sides exceeds 3℃, which will affect the dyeing, and the streak will appear when the temperature exceeds 5℃.

The machine is repaired.

c. Someone has tested that the temperature in the cylinder is basically even before and after the cylinder is turned for 10-15 minutes after the steam, and equal to the surface temperature. Therefore, the material is added, regardless of whether H202 is added during the chlorine cooking or the dye salt or soda ash during dyeing. Turn off the steam before charging.

9. Why ensure the process holding time after adding alkali?

The holding time should start to calculate the holding time after the alkali is added and the temperature is raised to the process holding temperature. Only by cutting the plate according to the process holding time, the quality can be guaranteed, because the holding time is determined according to how much time a certain amount of dye needs to react. The laboratory is also making samples at this time.

10. Several types of cutting boards that do not follow the process regulations cause unstable quality.

Time is not up to "right" color cutting board.

Due to the boarding problem, the material counting problem, the cloth weight bath ratio and other problems, the color deviation will be caused. The abnormality of the "right" color before the time is up should be reported to the monitor or technician. In any case, shorten the process and heat preservation time , The dye reaction is not sufficient, the color is not changed, the color is not uniform, there is no sense of fullness, and the fastness is also a problem.

Cut the board early and the feed is not accurate.

The dye uptake can only be stabilized when it reaches the process holding time. The earlier the cutting time, the greater the change and the more unstable. If the time has not reached the cutting time, (after cooking, training, washing, and drying, it will be given to the craftsman for color In the period from billing and weighing, the actual holding time of this tank cloth has been extended, and the dyeing has also increased at this time. The tank cloth is too deep after adding the replenishment material, and it has to be lightened again.)

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