Pre-treatment (bleaching) common quality problems with the selection of additives

Quality pre-treatment (bleaching) is not only related to product quality bleaching products, but also as semi-finished products, but also directly affect the dyeing, printing, finishing and other quality. Some experts say that the quality and finishing products, 70% are caused by poor pre-treatment, there is some truth in it, the quality and fabric dyeing and finishing, but not with the case and operate the equipment, and technology and the implementation of relevant and related dyes , and additives are also relevant, we focus on the effects of additives.

1.1 whiteness and capillary effect of poor problem
Including poor whiteness is not pure whiteness, uneven and 3Omin reach 8cm above the capillary effect, which is related to the quality of knitted fabric, such as lower cotton content more often whiteness and capillary effect is not easy to do, of course, the most critical is problem formulation and selection process aids in the development process in which:

(1) H2O2 and NaOH amount must be sufficient:
H2O2 treatment not only play the role of the former bleached pigment, but also has to miscellaneous effects (including to cottonseed hulls), H2O2 amount less (including decompose quickly), whiteness can not guarantee; NaOH H2O2 bleaching not only provide the necessary base (pH), and tie with a scouring agent, played the biggest role to miscellaneous insufficient amount of NaOH, to miscellaneous backward, first capillary effect can not meet the requirements. Of course, whiteness can not meet the requirements, so the amount of H2O2 and NaOH can be said that whiteness and capillary effect to ensure that the primary factor.

(2) high quality scouring agent:
Net wash scouring agent, emulsifying, dispersing, the combined effect of infiltration must be excellent in order to ensure the removal of impurities net to ensure whiteness and capillary effect, but the uneven quality of scouring agent on the market, we must choose the best products and the combined effect not just only for penetration and solid content, penetration is only one aspect to consider.

(3) oxygen bleach stabilizers and chelating dispersant:
This is mainly for two kinds of additives to improve the nature of water adsorption and complexation of Fe3 + and other metal ions to prevent the metal ion catalyzed decomposition of H2O2 produced rapid invalid, void if rapid decomposition of H2O2, its whiteness, capillary effect will reach requirements, but can cause damage or even holes in the fabric brittle. Therefore, to achieve whiteness and capillary effect, oxygen bleaching stabilizer to select the best varieties, important considerations in the selection of H2O2 decomposition rate. Join chelating dispersant is not only chelated iron, etc., and can chelate various impurities dispersed in water, so that these impurities are no longer re-stain fabric whiteness caused by phenomena such as dark gray, the chelating dispersant only to consider the metal ion chelating power but also consider the dispersion force.

(4) conditions:
Let additives react with impurities is take some time and temperature, if conditions fail, pigments and impurity removal without a net, the same whiteness and capillary effect can not be achieved.

(5) Washing:
After washing and bleaching is very important to clean down to remove impurities and ensure whiteness and capillary effect.

1.2 cottonseed hull removal without a net
Cottonseed hull removal mainly by NaOH under certain conditions, the expansion and swelling of the cottonseed hull, and then by some mechanical cleaning power to remove cottonseed hulls removed without a net is mainly caused by the temperature and time is not enough, it must be at a certain temperature sufficient time to completely remove the cotton seed hulls, H2O2 and scouring agent for cotton seed hull removal have some help, so there must be some pre-processing temperature and time to ensure that the cotton seed hull removal, while adding NaHSO3, or anthraquinone help in cottonseed hulls removed.

1.3 hole and brittle damage
Holes and brittle damage reason except singeing holes, processing tore the outer fabric of the original holes and other reasons, the main reason is H2O2 bleaching bath or cloth exist Fe3 +, Cu2 + and other metal ions; these metals fast ion catalyzed decomposition of H2O2, resulting in brittle fiber damage. If the metal ions to form holes, so in H2O2 bleaching elbow must choose high-quality oxygen bleach stabilizers and chelating dispersant (such as rust, etc.) are too concentrated in one place, then the fiber, yarn brittle damage to the complex, adsorption and fabric metal ions in the bleach bath, to prevent excessive decomposition of H2O2 cause holes or brittle damage. If you use bleach.

Of course, the cloth with alkali (to the base without a net) or with acid (acid not go to the net) can also cause brittle damage. Meanwhile, at high temperatures with a base case, the presence of air will be crisp fabric damage, this situation can be added NaHSO3 other weak reducing agent to prevent it.

In addition, the mold is also brittle and damaged one of the reasons the hole in the fabric damp.