Analysis of reactive dyes dyeing operation 9 big misunderstanding

Reactive dyes dyeing operation precautions. According to the market survey, reactive dyes are one of the most used dyestuffs in the current market, this article mainly summarizes 10 points of common operation misunderstandings and solutions for your reference.


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


(1) The purpose of using a small amount of cold water to adjust the slurry is to make the dye easy to fully wet through, if the dye is poured directly into the water that is, the outer layer of the dye to form a gel, the dye particles wrapped up, so that the dye particles are difficult to wet through the internal hard to melt, so it should be a small amount of cold water to adjust the slurry, and then use hot water to melt away.

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


2 Why should the dyestuff be added slowly and evenly?


This is mainly to prevent the dyes from dyeing too fast, if the dyes are added quickly at one time, the dyeing rate will be too fast, which will make the outer layer of the fibers deep and the inner layer shallow and easily cause the color flower or strip flower.


3 Why should we add salt after adding dyes for a certain period of time (e.g. 10min)?


Salt is a dyeing agent, when the dyeing reaches a certain degree, it is saturated and difficult to continue dyeing, adding salt is to break this balance, but before adding salt to promote dyeing, there is also a time of about 10-15min, so that the dyestuff can fully penetrate uniformly, or else it is easy to cause stripe flower, color flower.


4Why should salt be added in stages?


The purpose of adding salt in stages is to promote dyeing evenly, so as not to promote dyeing too fast, resulting in color bloom.

5 Why do we need a certain period of time (e.g. 20 minutes) to fix the color after adding salt.

There are two main reasons: 1) to let the salt dissolve evenly in the tank, fully promote the dyeing; 2) to promote the dyeing into the dyeing saturation to achieve equilibrium, and then add alkali to fix the color in order to achieve the highest dyeing volume.


6 Why does adding alkali become “fixing color”?

Reactive dyes plus salt only promote the role of dyeing, but adding alkali will stimulate the activity of reactive dyes, so that the dyes and fibers react under alkaline conditions (chemical reaction) so that the dyes are fixed on the fiber, so that the “solid color” is also due to this kind of color fixing chemical reaction, to achieve a higher degree of fastness. Once the color fixation color flower printing is difficult to be uniform.


7 add alkali why should be added in stages?

The purpose of adding in stages is to make the solid color uniform, to prevent the color flower. If a one-time addition is easy to cause the local residual liquid concentration is too high and the fiber reaction speed up, it will be easy to cause the color flower.


8 Why must the steam be turned off first when adding materials?

  1. The purpose of shutting off the steam before adding is to reduce the stripe difference and prevent color bloom.
  2. Control cylinder temperature rise on both sides of the temperature more than 3 ℃ dyeing has an impact, more than 5 ℃ appeared stripe flower, more than 10 ℃ downtime for maintenance.
  3. Some people have tested, pulling the cylinder is steam after turning 10-15 minutes before and after the cylinder temperature is basically uniform, and equal to the surface temperature, so add materials, regardless of chlorine cooking when adding H202 or dyeing when adding dyes, salt, soda ash, should first shut off the steam before adding materials.

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

Holding time should be from the addition of alkali, and warmed up to the process holding temperature before starting to calculate the holding time, only according to the process holding time shear plate, the quality is guaranteed, because the holding time is formulated according to a certain amount of dyestuffs need to be how much time for the reaction to determine the laboratory is also the time to proofing.

One comment

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