What are the quality problems in the pre-treatment process?

1. The problem of poor whiteness and gross effect

Poor whiteness includes impure whiteness, unevenness and less than 8～10cm/30min in the wool effect. This is related to the quality of knitted fabrics. For example, if the content of low-grade cotton is high, the whiteness and wool effect are often not easy to do well. The key is the process formulation and the selection of additives.

In process development:

① The amount of H202 and NaOH must be sufficient

H202: After the pretreatment, it not only plays the role of bleaching the pigment, but also has the effect of removing impurities (including removing cottonseed hulls). If the amount of H202 is insufficient (including too fast decomposition), the whiteness cannot be guaranteed. NaOH not only provides the required H202 bleaching Alkalinity (PH), combined with scouring agent, has the greatest effect of removing impurities.

② Choose high-quality scouring agent

The scouring agent must have excellent comprehensive effects such as cleaning, emulsification, dispersion, and penetration to ensure that impurities are removed, and whiteness and hair effects are guaranteed.

③ Oxygen bleaching stabilizer and chelating dispersant

These two additives are mainly used to improve water quality, adsorb and complex metal ions such as Fe3+ in water, and prevent metal ions from catalyzing the rapid and ineffective decomposition of H202. If H202 decomposes quickly and ineffectively, its whiteness and gross effect will not reach Requirements, it will also cause fabric brittleness or even holes, so to achieve whiteness and wool effect, the oxygen bleaching stabilizer should choose excellent varieties, and the decomposition rate of H202 should be considered in the selection.

④ Process conditions: It takes a certain amount of time and temperature for the additives to react with the impurities. If the conditions are not enough, the pigment and impurities will not be removed cleanly, and the whiteness and hair effect will also not be achieved.

⑤ Washing: Washing after scouring and bleaching is very important. It is necessary to clean and remove impurities to ensure whiteness and hair effect.