Polyester yarn

100% polyester 402 dyed spun yarn

The function and example of polyester dyeing reduction cleaning

Guide reading

The main reason is that the dyeing of polyester fiber is high temperature and high pressure. Although the disperse dye molecules are small, it can not guarantee that all dye molecules enter into the fiber during dyeing. Some disperse dyes will adhere to the fiber surface. If these floating colors are not removed, it will cause poor fastness. At this time, the strong reducing agent used for reduction cleaning will not destroy the dye molecules entering into the fiber, which can improve the fastness and improve the performance Color light.

Reduction cleaning classification of polyester

1、 Reduction cleaning in alkaline condition

Soaping agent + reducing agent (insurance powder or thiourea dioxide) + alkali (caustic soda or soda ash), however, many domestic dyeing factories do not use soaping agent.

Soaping agent: non-ionic surfactant, which is conducive to the solubilization, dispersion and re staining of floating color. The commonly used Pingjia O and nonylphenol polyoxyethylene ether np10 have good effect.

Cationic surfactant: it is especially suitable for completely removing the disperse dyes adsorbed in spandex, and significantly improving the color fastness of polyester / spandex dyes (especially dark color) (black nylon staining can reach 4-5 levels)

Reducing agent: compared with insurance powder, thiourea dioxide has the advantages of small odor, low dosage and high Sustainability (high unit price)

When the toner is used in the overflow dyeing machine, most of the reducing cleaning fluid will be consumed by oxygen in the air when spraying, while the open width washing can be used much less.

After the air in overflow dyeing machine was driven away by nitrogen in advance, it was found that the amount of powder can be greatly reduced.

2、 Reductive cleaning in acid condition

Soaping agent (same as above) + reducing agent (sulphites) + acid (acetic acid)

Advantages of reduction cleaning under acid conditions:

When the temperature is reduced to 80-90 ℃ after dyeing, the reductant used in acid condition is less consumed by air oxidation;

Reduction cleaning in acid condition is not omnipotent. In fact, compared with alkaline reduction cleaning process, reduction cleaning in acid condition is more effective for azo disperse dyes, while anthraquinone disperse dyes are sometimes not as effective as traditional alkaline reduction cleaning, which is why many dye factories use acid reducing agents to find that the effect is not as good as alkaline reduction cleaning.