Dyeing Process of Flame Retardant Modacrylic Fabric

Dyeing Process of Flame Retardant Modacrylic Fabric

First, modacrylic fiber is dyed with cationic dyes. It has the advantages of bright color and good color fastness.

Principle of modacrylic dyeing: the dyeing of modacrylic fabric is mainly the combination of salt bond, hydrogen bond and van der Waals force.

Second, several aspects to pay attention to when dyeing modacrylic with cationic dyes:

1. Solubility of dyes.

The solubility of cationic dyes in water is not good, and it is necessary to add acid to help dissolve. Generally, 1/3 of the dyeing acid is used for cationic dyes to be pulped, and then diluted with hot soft water at 80-90 degrees. Filter with a sieve when dyeing the vat. If the dissolution is not good, it will produce stains.

2. Dye saturation value.

There is a dye saturation value in acrylic dyeing. The third monomer on acrylic fiber is the dye seat when dyeing, which only accounts for a few percent of acrylic fiber. Therefore, the acidic groups on acrylic fibers are limited. Because the cationic dye and the acid group are directionally combined, when the acid group reacts with the dye cation, the acrylic fiber loses its ability to react. Therefore, the amount of our cationic dyes for dyeing acrylic is limited, generally 3-4%. Exceeding the saturation value will cause waste of dyes, and its color fastness is not ideal.

3. Cationic compatibility.

The speed of dyeing acrylic fibers with different cationic dyes is different, so the use of different dyes for color matching will cause mutual dyeing, and the result is uneven dyeing of acrylic fibers and color flowers. In order to avoid this from happening, we must use color matching with similar dye compatibility values. Generally can not differ by 0.5. Generally, cationic dyes will mark their compatibility values for each dye when they leave the factory for reference by dyeing factories. Compatibility value is 1---5 grade, 1 grade means that the dye is dyed the fastest, easy to color flowers, pay attention to the dyeing process control. Level 5 means that the dye is slow to dye and has good levelness.

4. Acrylic dyeing is easy to dye flowers. Therefore, the following measures should be taken to control the dyeing conditions during dyeing to ensure the dyeing quality.

(1) Control the dyeing heating rate. The glass transition temperature of acrylic fiber is about 70-85 degrees. After the temperature is higher than 85 degrees, the acrylic fiber segment moves violently, and cationic dyes will enter the fiber in large quantities to react with the carboxyl groups on the fiber. Dyeing is fairly quick and the result is uneven shades. Therefore, strictly controlling the heating rate is the key to controlling the color flower. Generally 0.2---0.5 degrees per minute.

(2) Retarder. Adding a retarder has a better effect on controlling the dyeing color. The commonly used retarders are cationic retarders, such as 1227, PAN. Their retarding principle is that the retarder reacts with the acrylic fiber first, occupying the dye seat, and gradually releases the dye after the temperature rises. seat, allowing the dye to react with the acrylic. So as to achieve the purpose of slow dyeing. Strict attention should be paid to the dosage when using the retarder. Unreasonable dosage may affect the color yield of acrylic fiber.

(3) PH value control during dyeing. The level of PH value will affect the speed of dyeing and the amount of dye uptake. When the PH value is low, the dissociation of carboxyl groups on the fiber is less, and the dyeing amount of cationic dyes is reduced, so it will play a role in retarding dyeing. On the contrary, adding less acid and high PH value will speed up the dyeing, and it is easy to dye flowers. Therefore, when the color is light, it is easy to dye the flowers, so more acid should be added, 2.5-3%, and 2-3% when the color is dark.

(4) The role of electrolytes. Sometimes dyeing will add electrolytes, table salt, or Yuan Ming powder. They have a retarding effect. Table salt and Yuanming powder leave NA+ in the dye liquor, and NA+ first reacts with the carboxyl group on the acrylic fiber. After the temperature rises, the NA+ ion will dissociate, leaving the dye seat, so that the dye and the acrylic fiber react.