Why do disperse dyestuff stains appear? How to prevent and cure?

Author：admin   Date：2017-12-09

Condensation in disperse dyes can cause color spots, stains and contamination of cylinders. How to prevent condensation of disperse dyes in dyeing?
1. Principle of the production of dye condensation
The diameter of the general disperse dye is about 1pm, the diameter of the polyester fiber is about 15pm, and the gap between the single fiber is about 5um. Under normal conditions, dye particles can freely pass through the gap between single fibers. If condensation occurs, the diameter of dye particles may exceed 5um, which is blocked outside the single fiber gap and is difficult to achieve the dyeing reaction.
The coagulated dye stays on the fabric and becomes a visible spot (stained spot) when the length is more than 100um.
Two. Causes of dye condensation
The cause of the dye condensation is multi angle, usually because of the following reasons:
1, the cause of operation: the material is not complete;
2, polyester raw materials: polyester oligomers more;
3, dyeing water: the hardness is high, the influence of metal ions in the water;
4. The heating rate is too fast in the dyeing experience.
Three. How to avoid the condensation of dyestuffs
In order to prevent the condensation of the dye and strengthen the dispersion of the dye, the usual way is to add the dispersing agent. With the help of dispersant, the disperse dye can form a dispersed homogeneous phase in the dye and realize the dyeing effect.
In order to maintain good suspension and disperse state of dyestuff particles in dyeing experience, a lot of anionic surfactants, such as dispersant NNO, sodium lignosulfonate, etc., are dyed in commercial dyes. However, in high temperature and high pressure dyeing bath, diffuser NNO and so on are easy to be analyzed from the surface of disperse dye crystal particles, and dye particles will further coagulate and adhere to cloth surface, resulting in stain defects.
The following two angles can be done to solve the problem
1. Select the dispersant with good thermal stability. Sodium sulfonic acid, such as phenol or naphthol, and the condensation of formaldehyde.
2. Add other surfactants in the bath to increase the stability of the dye bath. Generally, nonionic or anionic surfactants can be added. Non ionic surfactant cloud point although most at 100 DEG C, penetrating agent JFC cloud point only 50 degrees Celsius, but because the existing anionic surface active agent, the cloud point will increase, also can be used in high temperature dyeing, as long as the varieties with proper dosage, not only can play a good dispersion. Also can play the retarding effect, achieve the leveling effect.