10 points to note: precautions for reactive dye dyeing operations. According to market research, reactive dyes are one of the most widely used dyes in the market. This article mainly summarizes 10 common operating misunderstandings and solutions for your reference.
1. Why is it required to use a small amount of cold water to mix the slurry first when mixing the materials, and the temperature of the mixing materials cannot be too high?
(1) Use a small amount of cold water to mix the slurry first to make the dye easily fully wet. If you put it directly When the dye is poured into water, the outer layer of the dye will form a gel, which will wrap the dye particles, making it difficult for the inside of the dye particles to get wet and melt. Therefore, a small amount of cold water should be used to mix the slurry first, and then hot water should be used to melt it.
(2) If the temperature of the chemical material is too high, it will cause hydrolysis of the dye and reduce the dye fixation rate.
2. Why do you need to add ingredients slowly and evenly?
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 high. If it is too fast, the outer layer of the fiber will be dark and the inner layer will be shallow, which can easily cause colored flowers or streaks.
3. After adding the dye, why does it take a certain period of time (for example: 10 minutes) before adding salt?
Salt is a dye accelerator. When the dye is dyed to a certain extent, it has reached saturation and it is difficult to continue dyeing. Adding salt to dyeing is to break this balance, but it takes about 10-15 minutes before adding salt to promote dyeing, so that the dye can fully penetrate evenly, otherwise it will easily cause stripes and color flowers.
4. Why should salt be added in batches?
The purpose of adding salt in stages is to promote dyeing evenly, so as not to promote dyeing too quickly and cause color blooming.
5. Why does it take a certain period of time (such as 20 minutes) to solidify after adding salt.
There are two main reasons: A. To allow the salt to dissolve evenly in the tank and fully promote dyeing B. After the dyeing is allowed to reach dye saturation and equilibrium is reached, alkali is added to fix the color to achieve a high dye uptake.
6. Why does adding alkali become “fixed color”?
Adding salt to reactive dyes can only promote dyeing, but adding alkali will stimulate the activity of reactive dyes, causing the dyes to react with The fiber reacts (chemical reaction) under alkaline conditions to fix the dye on the fiber, so it is called “fixation” because of the chemical reaction that occurs in this fixation, achieving higher fastness. Once solidified, the color print will be difficult to achieve evenly.
7. Why should alkali be added in stages?
The purpose of adding in batches is to make the color solid evenly and prevent color blooming.
If added at one time, it will easily cause the local residual liquid to be too high in concentration and react with the fiber faster, which will easily cause color blooming. .
8. Why must the steam be turned off first when adding materials?
a. The purpose of turning off the steam before adding materials is to reduce the stripe difference and prevent color blooming.
b. When the temperature on both sides of the controlled cylinder rises above 3℃, dyeing will be affected, and stripes will appear when the temperature exceeds 5℃. If the temperature exceeds 10℃, stop the machine for maintenance.
c. Some people have tested that the temperature in the cylinder is about 10-15 minutes after the cylinder is turned. It is basically uniform and equal to the surface temperature, so when adding materials, whether adding H202 during chlorine boiling or adding dye salt or soda ash during dyeing, the steam should be turned off before adding materials.
9. Why ensure the process holding time after adding alkali?
The holding time should be calculated from when the alkali is added and the temperature is raised to the process holding temperature. Only Only by shearing the boards according to the process holding time can the quality be guaranteed, because the holding time is determined based on how long it takes for a certain amount of dye to react, and the laboratory also produces samples at this time.
10. Several types of board shearing that do not follow process regulations cause unstable quality.
The time is not up to cut the “right” color board.
Due to problems such as plate making, material weighing, cloth weight and bath ratio, etc., problems will cause color deviation and time. Abnormalities such as colors that have not been “corrected” should be reported to the squad leader or craftsman. In any case, the process and holding time are shortened, the dye reaction is not sufficient, the color does not change, the dyeing is uneven, there is no fullness, and the fastness is also a problem.
Cut the board early and replenish the material incorrectly.
The dyeing can only be stable when the process heat preservation time is reached. The earlier the cutting time, the greater the change and the more unstable. If the cutting time is not up, (after boiling, scouring, washing, and blow-drying) Craftsman looks at color , between the time of ordering and weighing, the actual heat preservation time of the vat cloth has been extended, and the dyeing has also increased. The vat cloth is too dark after adding the supplementary material, and it needs to be lightened again.)
There is no benefit in extending the time to cut the board.
When the board is cut by the insulator, the dye reaction has ended, and it is useless to dye it again. Instead, it will cause some Already dyed dyes are re-hydrolyzed.
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