Disperse dyes are prone to problems such as uneven dyeing, recrystallization, agglomeration and coke aggregation. How to prevent them is as follows:

1. Uneven dyeing

The degree of uniformity of the absorbing dye is related to the ratio between the dye flow rate and the absorbance. In the color absorption phase, the flow direction is changed every 8 cycles. By reducing the bath ratio from 1:12 to 1:6, the uniformity of the migration phase can be changed, although the degree of unevenness in the beginning of the dyeing is more pronounced. When blending dyes, it is not sufficient to select only dyes with similar diffusion properties to ensure level dyeing.

At this time, the mixing ratio plays an important role. If the three dyes used in the color matching are the same amount, it is correct to use the dye with the same diffusion property. However, if the ratio of the two dyes is larger, and the diffusion of the third dye is lower, it will be faster than the other two dyes, and it is easy to cause uneven dyeing.

2. Recrystallization

Disperse dyes are often reheated and cooled, recrystallized particles larger than 1 nm, and additional dispersing agents are added to minimize recrystallization. When dyeing, when the dye bath is cooled from 130 ° C to 90 ° C, some dyes tend to recrystallize, resulting in poor rubbing fastness of the dye, and even clogging the filter in the high temperature and high pressure dyeing machine.

The preventive measures are:

1 Keeping 100 ° C for a long time, the dye is easy to agglomerate, and the temperature is raised from 100 ° C to 130 ° C;

2 If the dye is recrystallized in the dyebath after reaching the dyeing balance, more dispersing agent must be added;

3 Some onion-type red disperse dyes such as CI disperse red 53, 60, 92, 121, 132, 159, etc., at the end of dyeing, even if the concentration is much lower than the saturation level, it is prone to recrystallization, when dyeing darker colors Especially obvious. Especially when dyed with hard water, it is easy to chelate with metal ions. The resulting chelate is less soluble under dyeing conditions and leaves blue spots or colored stripes on the fabric.

The factors that cause recrystallization are:

Adding auxiliaries, winding oils, alkaline residues, etc. during spinning. These problems can be well avoided by refining before dyeing or by adding a chelating agent to the dye bath (Dongguan Hongqi produces well). Once the stain occurs, it can be eliminated by alkaline reduction cleaning or acid treatment.

3. Agglomeration and coke

The factors are: weakening the dissolution of the dispersant, reducing the mutual repulsion of the static electricity, and increasing the collision rate of the dye particles and increasing their kinetic energy. In general, the higher the dyeing concentration and temperature, the longer the dyeing time, the greater the possibility of agglomeration and coke. The dyeing assistants such as the carrier and the leveling agent (good in Dongguan Hongqi) are easy to displace the dispersing agent mixed in the dye, thereby reducing the dispersion stability.

Measures to improve the stability of dyeing are:

Disperse the dye at 140 ° C and use a concentrated dispersion;

2 temperature control is best when dyeing liquid is heated;

3 using a dispersing agent having a protective colloidal action;

4 no need for turbidity additives at high temperatures;

5 Wash all dyes and yarn auxiliaries including emulsifiers before dyeing;

6 When dyeing at high temperature, no carrier or non-ionic leveling agent should be added until most of the dye has been dyed on the fabric;

7 without salt, only adjust the pH with acetic acid;

8 yarn or piece dyed fabric should be properly shaped and laboratory tests to ensure dispersion stability of the disperse dye.

Changzhou Lingda Chemical Co., Ltd. main production and management: SORONA, Carpet adhesive, adhesive additives, silicone oil series, Carpet adhesive, polypropylene filament oil, polyester filament oil, polypropylene BCF plying stereotypes yarn, Carpet adhesive, Polypropylene carpet silk, polypropylene BCF yarn.