Which desizing method is good for denim clothing

1. Sizing on denim fabrics and desizing in the processing stage of denim fabrics

Denim warp yarns are generally pure cotton yarns, and the yarns go directly into the dyeing tank for dyeing after simple refining. If the sizing and dyeing machine is used, the yarn dyeing and sizing are completed at one time; if the ball warping dyeing machine is used, it needs to be re-warped and then sizing after dyeing. Since most denim fabrics are thick and high-density fabrics, they are generally woven by rapier looms with high speed and high tension. At the same time, the warp yarns are dyed before weaving, and the yarns are greatly damaged by abrasion during weaving. Good adhesion and abrasion resistance. The commonly used sizes for denim warp sizing include starch, modified starch, PVA and acrylic size, and the sizing rate is generally 6-8%.

After the denim grey fabric is off the machine, it is generally subjected to post-finishing, in which singeing removes the hairiness on the fabric surface; pre-shrinking eliminates warp tension and reduces shrinkage; mercerizing improves the luster and stability of the fabric; softness improves the sewing performance of the fabric. In order to meet the requirements of shrinkage rate, amylase is generally used for partial desizing of fabrics. In order to facilitate the subsequent garment processing, desizing does not need to be too sufficient, and it can meet the requirements of shrinkage rate.

2. Why do denim clothing still need desizing?

Since the denim fabric is only half desizing during the finishing process, the fabric still has some pulp on the denim garment after it is made. The existence of these slurries leads to poor permeability of the fabric, and cannot absorb chemicals (dyes, fixatives, enzymes, softeners and anti-wrinkle agents, etc.) well in the subsequent processing, which affects the effect of subsequent processing; Fabrics with pulp are relatively stiff. When washed in a washing machine, the friction with the machine is prone to watermarks, white spots, creases and other defects. Therefore, desizing is an essential and important part in the washing and processing of denim garments.

3. Commonly used desizing methods and their effects

(1) Hot water wash

In order to save costs, many manufacturers use hot water desizing. Hot water can only dissolve some water-soluble pulp, can not degrade the pulp, the viscosity of the pulp can not be reduced, the desizing rate is low, and the pulp dissolved in the hot water will re-stick to the clothing, so the application of this method very limited.

(2) Alkali desizing

The ability of caustic soda to remove starch is strong, and at the same time, it has a certain decontamination ability. Due to the action of alkali and cotton cloth, it is difficult to remove the residual alkali on the cloth surface, and it is necessary to increase the number of cleanings. If the cleaning is not clean, it will affect the subsequent color registration and enzyme washing process. If the clothing fabric contains polyester components, the alkali will also cause damage to the polyester fibers.

(3) Softener desizing

Softeners are generally aliphatic cationic compounds or macromolecular silicone oils, which have no cleaning ability and no desizing effect. Some manufacturers use softener to desizing, in fact, the main function is to increase the lubrication of the clothing surface and prevent the appearance of washing marks. However, due to the cationic nature and water repellency of the softener, it is easy to cause problems such as difficulty in enzymatic washing, staining, and uneven horses.

(4) Desizing with detergent

Some manufacturers use washing powder for desizing. The washing powder has a good cleaning effect and has a certain ability to remove the pulp. However, when it is used for denim desizing, the staining phenomenon is serious. Large influence, easy to inactivate enzymes. Non-ionic sap oil has good wetting, emulsifying and cleaning functions, as well as anti-staining ability and smoothing effect. It is used by many manufacturers, but the desizing effect is general.

(5) Desizing enzyme desizing

Desizing enzyme is a complex with α-amylase as the main component. Generally, mesothermal amylase is used in washing plants. The effect of single amylase is not good. Desizing effect of pulp. Compared with other desizing methods, desizing enzyme can clean starch-containing pulp without damaging the fiber, has strong color retention ability, fluffy and soft hand feeling, and is especially suitable for color retention and washing.

(6) Desizing of stone powder

The stone grinding powder is composed of ultra-fine abrasives and a variety of organic components. It can be used for desizing of heavy denim. It can not only remove the slurry, but also abrad the surface of the fabric. In the desizing stage, a part of the stone grinding effect is produced. , which can greatly reduce the amount of enzymes in the subsequent fermentation process, shorten the fermentation time, and is especially suitable for denim desizing with high contrast requirements.

(7) Bleaching and desizing

Bleaching water itself has strong oxidative properties and a certain degree of alkalinity, which can degrade the pulp. At the same time, it has a certain bleaching effect, which can significantly improve the brightness of the cloth surface, but when used alone, the color will fade and the shade will also change. , It is necessary to add chlorine bleach protection agent to not only desizing, but also to ensure that the color does not fade. Using bleaching water and a small amount of caustic soda and chlorine bleaching protective agent together, to desizing denim fabric, the color does not change after desizing, the shade does not change, and the cloth surface does not flower, especially suitable for black cow desizing, which can effectively remove The sulfur smell of black bull.

4. What are the ways to solve denim wear marks?

Denim wear marks are mainly caused by the stiffness of the fabric, which is caused by friction with the machine after being squeezed and wrinkled. It can only be avoided by removing the pulp in a short period of time. Increasing the temperature, increasing the amount of desizing agent, increasing the bath ratio, and reducing the entanglement of clothing have certain effects. In addition, adding some special diffusing agents during desizing has obvious effects.

5. Is low temperature desizing feasible?

Whether low-temperature desizing is feasible or not depends on whether the slurry can be quickly removed at low temperature. At present, the use of bleaching water desizing and desizing enzyme desizing is better at low temperature. Compared with 50 ℃ desizing, low temperature desizing The color of clothing is pure and bright, which is more suitable for consumers' needs, and at the same time saves energy, it is worth trying.

6. How long is the desizing time appropriate?

At present, the desizing time of the factory is controlled at 10-20 minutes, but the current denim style tends to be more fluffy and natural tones. Properly extending the desizing time is the most effective method, but the premise is that the color must not fade too much, and low temperature can be used. Change to cold water after desizing or 50°C to quickly remove the slurry.