The Common Quality Problems Of Knitting Dyeing And Finishing Products And The Selection Of Additives

The common quality problems of knitting dyeing and finishing products and the selection of additives

At present, the dyeing and finishing industry is booming and the industry situation is very good. However, with the expansion of production volume, the knitting and dyeing factories in various places reflect the quality of dyeing and finishing, and the disease of dyeing and finishing products is the quality of dyeing and finishing products. The important factors can also show the level of production level, management level and equipment technology of dyeing and finishing factories. In the production, due to grey cloth, semi-products, equipment, process level and implementation, quality of dyeing materials, etc., quality problems may occur. The selection and quality of additives directly affect the quality of dyeing and finishing products. Aiming at the problems of the common quality problems of dyeing and finishing products of knitted fabrics and the relationship between the selection of additives.

1 Pre-treatment common quality problems and selection of additives

The quality of pre-treatment (practice bleaching) is not only related to the quality of the finished product of bleaching, but also as a semi-product, it will directly affect the quality of dyeing, printing and finishing. Some experts said that 70% of the quality problems of dyeing and finishing products are caused by poor pre-treatment, and there are certain reasons. The quality of dyeing and finishing is related to the grey fabric, related to the equipment and operation, related to the process technology and execution, related to the dye, and related to the auxiliary. We focus on the influence of the additive.

1.1 Whiteness and poor hair efficiency

Poor whiteness, including whiteness is not pure, uneven and the hair effect is less than 8~10cm/30min. This is related to the quality of knitted fabrics. For example, low-grade cotton has many contents, and often whiteness and hairiness are not easy to do. Of course, most The key is the process development and the selection of additives. In the process development:

The amount of 1H202 and NaOH must be sufficient.

H202: not only plays the role of bleaching pigment after pre-treatment, but also has de-doping effect (including cottonseed shell), the amount of H202 is insufficient (including decomposition too fast), whiteness is impossible to guarantee, NaOH not only provides H202 bleaching Alkalinity (PH), and with the scouring agent, the maximum degumming effect, the amount of NaOH is insufficient, the impurity is poor, the wool effect can not meet the requirements first, of course, the whiteness can not meet the requirements, so the amount of H202 and NaOH It can be said that it is the primary factor to ensure whiteness and gross effect;

2 use high quality scouring agent:

The comprehensive effects of scouring agent such as cleansing, emulsifying, dispersing and infiltrating must be excellent to ensure the removal of impurities and ensure whiteness and gross effect. However, the quality of scouring agents on the market is uneven, we must choose products with excellent comprehensive effects. Not only the permeability and solid content are measured, but the penetration is only one aspect considered;

3 oxygen bleach 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 inefficient decomposition of H202. If H202 decomposes rapidly, its whiteness and gross effect will not be achieved. Requirements, at the same time will cause fabric brittleness or even hole, so to achieve whiteness and hair effect, oxygen bleach stabilizer should choose excellent varieties, in the selection should focus on the decomposition rate of H202. The addition of the chelating dispersing agent not only chelate iron or the like, but also chelate various impurities in the water, so that the impurities do not re-stain the fabric and cause whiteness and dark ash, so the chelating dispersing agent is not only Consider its chelation to metal ions and also consider its dispersing power;

4 Process conditions: It takes a certain time and temperature to react the auxiliary agent with the impurities. If the conditions are not enough, the pigment and impurities are not removed properly, and the whiteness and the gross effect can not be achieved:

5 Washing: It is very important to wash after bleaching. It is necessary to clean and remove the impurities to ensure whiteness and hairiness.

1.2 Cottonseed hull removal is not clean

The removal of cottonseed hull mainly relies on the expansion and swelling of cottonseed hull under certain conditions, and then removes the cottonseed hull by a certain mechanical washing power. The removal of uncleanness is mainly caused by insufficient temperature and time, so it must be sufficient at a certain temperature. Time can completely remove the cottonseed hulls. H202 and scouring agent can help the removal of cottonseed hulls. Therefore, there must be a certain temperature and time in the pretreatment to ensure the removal of cotton husks. At the same time, NaHS03 or guanidines can be added to help. Cottonseed hulls are removed.

1.3 Holes and fragility

The main reason is the presence of Fe3+, Cu2+ and other metal ions in the H202 bleaching bath or on the cloth surface, in addition to the singeing holes, the smashing during processing, the original holes in the grey cloth, etc. Metal ions catalyze the decomposition of H202 for rapid decomposition, resulting in fiber brittleness. If metal ions (such as rust, etc.) are too concentrated in one place, the fibers and yarns are fragile and form holes. Therefore, H202 bleaching must select high-quality oxygen bleach stabilizers and chelating dispersants to complex, adsorb fabrics and bleach baths. The metal ions in the metal prevent the H202 from decomposing too quickly to cause holes or brittleness. If the mercerizing base is used for bleaching, it is necessary to ensure that the alkali does not contain impurities such as rust.

Of course, the cloth with alkali (not alkali) or with acid (de-acidized) can also cause brittleness. At the same time, in the case of high temperature with alkali, the fabric will be brittle in the presence of air, which can be prevented by adding a weak reducing agent such as NaHS03.