How to deal with the yellowing of fluorescent whitening agent?

1. in the process of consumption, a series of corresponding measures should be taken, for example, in the process of boiling and bleaching, the water washing after pickling must be abundant; soaping should maximize the residue of soap; whitening should use soft water and control the pH value of alkaline (pH 8-9); fluorescent whitening agent should choose products with better acid resistance.

2. The traditional technological process is scouring and bleaching hot water washing peracid deoxidation water washing. Glacial acetic acid is used after hot water washing. Glacial acetic acid is a volatile acid, which can only neutralize the caustic soda on the surface of the fibers and is difficult to penetrate into the outside of the fibers. Especially for heavy fabrics, caustic soda is often left outside the fibers. Therefore, the use of neutralizing acid can not only neutralize the caustic soda on the outside of the fibers, but also neutralize the caustic soda on the outside of the fibers, so that the effect of complete neutralization can be achieved. At the same time, the time and temperature of overacid should be strictly controlled so as to neutralize thoroughly, so that overacid time can be properly extended. This is especially important for the bleaching of heavy fabrics.

3. Selection of softeners. Cationic softener, weak cationic softener and ordinary silicone oil can cause yellowing of white fabrics at different levels. Therefore, softeners should be selected and confirmed.

4. Fabrics should be processed to prevent contact with gases such as acid or chlorine.

5. To control water quality, soft water should be used as far as possible. Water quality has high hardness, whitening effect will decrease. Heavy metal ions such as acid, free chlorine, copper and iron in water can obviously affect the whitening effect.