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Why does acrylic dyeing cause fuzzy color? How to solve it?

From: FAQ | Date:2020/8/14 | Hit:

Core Tips: Reasons for blooming:

1. Improper selection of dyes

2. Improper selection and use of levelling agent

3. Differences in raw materials

4. Improper control of temperature rise

5. Changes in pH value

6. Impact of water quality

Reason for ochre flower:

1. Improper dye selection
Dyeing acrylic fiber is different from dyeing other fibers. If the dye is not selected properly, it is difficult to achieve the leveling effect even by adding more leveling agents or improving the dyeing conditions. Therefore, the cationic dyes should be selected with the same compatibility value, and the difference in the compatibility value of the dyes in the formula should be less than 0.5.

2. Improper selection and dosage of levelling agent
⑴Acrylic levelling agents are divided into two categories: slow dyeing levelling agents and transfer dyeing levelling agents
a. The retarding levelling agent is also called retarding agent. The retarding principle of retarding leveling agent is as follows: When dyeing, the retarding agent preempts the dyeing seat, and as the temperature gradually increases, the retarding agent is dyed. Instead, it can be combined with fibers to achieve the purpose of leveling.
的 Precautions for using retarder:
① If the amount is small, the leveling effect is not good, and it is easy to cause color bloom. If you use too much, it will cause bloom.
②The key temperature for most acrylic dyeing is about 90 ℃. If the amount of PAN is appropriate, it can be dyed at a constant speed by holding at 90 ° C for 20 minutes. If it is too much, it will cause the dyeing temperature to rise and the dyeing speed will increase, which will cause color bloom.
Take ZJ-CH13 cationic levelling agent as an example. Generally speaking, the amount of dark color is 1g / l, and the amount of medium light color is 0.2-0. 5g / l.
B. Transfer dye leveling agent: It has the performance of migration and transfer, which can transfer the dye from the dark place to the light place.

3. Differences in raw materials

Acrylic fibers produced by domestic companies have different dyeing properties. For example: Shanghai Jinshan Chemical Plant's acrylic fiber is colored fast, Lanzhou Petrochemical's acrylic fiber is colored slowly, which brings great difficulties to the dyeing plant.

4. Improper temperature control
Generally speaking, acrylic fiber starts to be colored from 80 ℃, and the key stage of coloring is between 87-92 ℃. During this period, the temperature must be slowly increased, and the speed is between 1 ℃ / 3 minutes --- 1 ℃ / 6 minutes. It is best to keep it at 90 ° C for 20 minutes.

5. PH value change
When dyeing acrylic, the pH value should be between 3.5-5.5. When the pH value is low, the dyeing speed is slow and it is not easy to dye flowers. However, the pH value is too low, and the fastness to dyeing is poor. When the pH value is high, the dyeing speed is fast and the color is high. However, when the pH is too high, it is easy to dye flowers. If the pH is higher than 6, it may cause discoloration.
Generally speaking, the pH value of dyed acrylic fiber is around 4.5. Acrylic acid is used for dyeing acrylic fiber. In order to ensure that the pH value tends to be stable during the whole dyeing process, sodium acetate is added as a pH buffering agent in the dyeing bath, so that the dyeing and coloring process does not change with the fluctuation of pH, and the leveling effect is achieved. The dosage of sodium acetate is generally 0.5g / l.

6. Impact of water quality
Soft water is used for dyeing acrylic fiber, and the total hardness value is below 75PPM. If the hardness of the water is high, it will cause dyeing. Some dyeing plants often experience dyeing, which may be caused by too high water hardness.
In summary, dyeing acrylic is compared to dyeing other fibers. The difficulty is higher, and many factors are considered when formulating the process. How to formulate an optimal dyeing process, it is recommended that the laboratory proof the process multiple times.
Normal temperature
This heating process is a more general dyeing process. Customers can make appropriate adjustments according to the type of cloth and yarn dyed. such as:
①The temperature of the cloth with a small gram is warmed up slowly, while the cloth with a large gram may heat up faster.
② The temperature of high count yarn should be slower, while the temperature of low count yarn can be faster.
③ darker colors can be warmed up faster, lighter ones should be warmed up more slowly
④ The dark color should be kept longer at 98 ℃, 45 minutes-60 minutes, but the light color only needs
Keep it warm for 15 minutes.

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