Several factors that affect the washing effect of denim
Strong trousers have endured for a long time due to their unique charm of rugged texture, nostalgic style, wear-resistance, crispness and comfortable wearing, not because of their style and production process. The changes in the process mainly lie in the ever-changing post-finishing process. In order to obtain a unique appearance of the firm trousers, the firm trousers must be washed using processes such as stone grinding, snowflake grinding, enzyme grinding, and sand washing.
The finishing process after washing is a key process to make the strong trousers obtain a unique style. Among the many factors that affect the washing effect of the strong trousers, the following are additives, pH value and liquor ratio. Factors are analyzed and discussed.
1. The influence of additives on the washing effect of strong woolen trousers
In the washing process of strong woolen trousers, additives play an important role in the washing effect. Denim fabrics are generally pure cotton fabrics. Chemical or physical additives interact with the fibers or dyes on the surface of the fabric to a certain extent. In addition, a certain mechanical external force causes a certain degree of wear and damage to the fibers on the surface of the cotton fabric, or removes the inner fibers of the cotton fabric. Some dyes and pigments are used to achieve a certain wear and fading effect.
1. The effect of additives on the stone grinding effect of firm trousers
1.1 General finishing mechanism after stone grinding
After stone grinding, the pumice stone containing sodium hypochlorite and the strong trousers that have been desized in advance are placed in an industrial washing machine for stone grinding treatment. The friction between the pumice and the solid trousers, the mutual friction between the solid trousers and the solid trousers, and the action of the drum wall of the clothes washing machine partially wear away the dye on the surface of the solid trousers, and at the same time, a large amount of ash containing sodium hypochlorite is produced. Slag powder. It can be seen that the main chemical additive for stone washing is sodium hypochlorite. Because it is a strong oxidant, it can destroy the indigo or sulfide melanin on the denim work clothes and play a certain role in stripping and bleaching. Since the ash powder stuck to the work clothes varies in weight and is extremely uneven, the shape, amount and size of the discoloration and whitening are also irregular.
1.2 Mechanism of finishing after snow grinding
Snowflake milling belongs to stone grinding. Its process principle is roughly the same as that of general stone grinding. The main difference lies in the selection of chemical additives. Generally, stone mills usually use sodium hypochlorite as a strong oxidant, while snowflake mills mostly use potassium permanganate. In addition to removing the dye on the surface through the friction between pumice, strong trousers, and the wall of the washing machine drum, it mainly releases oxygen through the reduction of the potassium permanganate solution in the pumice itself, resulting in strong oxidation of the pigment. Make it evenly decolorized and achieve a uniform snowflake shape effect. The size and shape of the snow-polished pumice particles should be similar, generally round and about the size of an egg. The size of the pumice stone for general stone washing is generally 1-2cm, and the sizes vary, thus forming an irregular white snowflake effect. The indigo firm trousers after snowflake polishing have a wide white surface, and the whiteness is whiter. The contrast between the blue background and the white surface is greater, unlike stone polished white which is more uniform, the blue and white contrast is small, and the snowflake polished surface is whiter. The white area is like a large pile of snowflakes, covering the pants, giving it a natural and romantic style like “blue sky and white clouds”.
2. The effect of additives on the sandblasting effect of strong trousers
The raw materials for sandblasting include emery and potassium permanganate. Both are sprayed at high pressure to the fixed parts of the trousers, usually on the front and rear sides of the thighs and buttocks, so that the color of the surface changes. Shallow to achieve a worn effect. The former is called sandblasting, and the latter is called sandblasting. Due to the different raw materials used in the two, different properties of fading reactions occur, resulting in differences in washing effects.
Sandblasting and spraying are both carried out before desizing and washing. Sandblasting is powered by compressed air. Through a spray gun, high-energy angular emery material is sprayed onto a certain part of the firm trousers. The sand material has a strong impact on the surface of the firm trousers, causing the surface pigment to fall off, thereby achieving a kind of fading. Effect. It can be seen that sandblasting mainly uses emery as the raw material, and causes the denim fabric to undergo a fading reaction through physical effects. Spraying maliu is to use a spray gun to spray chemical solvents such as potassium permanganate or sodium hypochlorite on fixed parts of strong trousers, such as the buttocks. Potassium permanganate droplets are evenly distributed on the surface of the denim fabric, causing the fabric to undergo a chemical reaction and fade. The mechanical impact of sandblasting causes the slurry layer of the strong trousers fabric to vibrate loosely or vibrate to achieve a soft and loose effect. Therefore, sandblasting causes physical damage to the surface layer of the fabric, and only has a fading effect on the surface layer without a sense of hierarchy. Spraying Magali uses potassium permanganate as an auxiliary, which has a strong oxidation effect with the pigment of denim fabrics. Therefore, Spraying Magali can achieve a strong fading effect, and the fading is even, both on the surface and inside.The layers are faded and have a layered feel.
2. The influence of liquor ratio and temperature on the washing effect of firm trousers
The washing process of strong trousers is mostly based on a series of complex chemical reactions. Different manipulations of temperature and solvent amount will have different effects on the washing effect. The liquor ratio is the ratio of the weight of the fabric to be washed and the auxiliary. It is used to express the amount of auxiliary in the dyeing and finishing profession. Taking the enzyme washing process as an example, the impact of two important factors, temperature and bath ratio, on the enzymatic washing effect is analyzed.
1. Enzyme washing mechanism of strong woolen pants
Enzyme washing uses cellulase as the main chemical additive. Based on the different pH values suitable for the enzyme, cellulase is divided into Denimax enzyme (neutral cellulase) and Denimax enzyme.
Acid enzyme (acid cellulase). Strong trousers are generally made of cotton fabric, which is composed of cellulose fibers. Enzyme washing uses cellulase to hydrolyze cellulose fibers, causing part of the fiber on the surface of the denim fabric to dissolve. Indigo, sulfur, vat and other dyes are also shed with the help of the friction and kneading of the washing equipment, thereby achieving a “worn-in” feeling. Effect. After enzyme washing, the fabric has little strength loss, the surface is clean, has a unique and bright appearance, and the fabric’s softness, drape, water absorption, etc. are also improved.
2. Effects of liquor ratio and temperature on enzyme washing effect
In the enzymatic washing process of strong trousers, the liquor ratio is a key factor. If the liquor ratio is too small, the fabric will have too little liquid and the friction will be uneven, which will affect the enzyme washing effect. If the liquor ratio is too high, the dosage of enzyme will be large, which will increase the cost. The large amount of liquid will make the fabric easily float on the liquid surface and interact with the enzyme. The contact is not close and the friction is not sufficient, which will greatly damage the fabric and reduce the strength of the strong fabric after enzyme washing. For common denim, the liquor ratio is generally controlled at 1:10-15. For thick, wear-resistant and strong trousers, a small amount of pumice can be added during cellulase treatment, which can improve the efficiency of enzyme washing and produce a unique stone-washed white style. Furthermore, the activity of the enzyme can only be maintained optimally under specific temperature conditions. If the temperature is too high or too low, the activity of the enzyme will decrease or even lose its activity. As a result, the hydrolysis reaction of the enzyme will be insufficient and the final fading effect cannot be achieved. Generally, the temperature when cellulase has optimal activity is 40℃-60℃. For example: the optimal operating temperature of acid enzyme is 55℃. 65℃ will cause the enzyme to lose activity, and 30℃ will reduce the enzyme performance. It can be seen that the two major factors of temperature and liquor ratio have an important impact on the effect of enzyme washing.
3. The influence of pH value and time on the washing effect of firm trousers
During the enzymatic scrubbing process, the indigo dye suspended in the aqueous solution will have a strong back-staining tendency on the surface of the strong trousers, and the seams and inner pockets of the garment will turn blue. . This back-staining tendency mainly depends on the pH value of the water bath. There is obvious back-staining phenomenon when the pH is below 6. It can be removed by light bleaching with sodium hypochlorite or hydrogen peroxide. The activity of acid enzyme is high, it has a high corrosive effect on cellulose fibers, and it has a large loss of strength on cotton fabrics, but it can complete the wear in a short period of time. Generally, the acid enzyme washing time is controlled at 45-90 minutes. The activity of neutral enzyme is low, the corrosion effect on cellulose fibers is weaker than that of acidic enzyme, and the loss of fabric strength is small. However, the washing time of neutral enzyme is longer, generally controlled at 60-120 minutes.
4. The influence of other factors on the washing effect of firm trousers
In addition to the above factors that have an important impact on the washing effect of firm trousers, there are other factors such as differences in process operation equipment that will also lead to differences in washing effects. For example, both of them have been groomed with whiskers, but they show different style effects. One is a cat whisker-like pattern, showing a white shadow effect, while the other cat whisker pattern is honeycomb-shaped, with a strong sense of standing and a sense of hierarchy than the former.
The difference between the two is mainly due to the different operating equipment and tools. The former is called hand-wiping cat whiskers, which is mainly done by hand. First, the area to be wiped by hand is placed on a rubber plate engraved with the shape of convex and concave cat whiskers, and then manually rubbed with sandpaper on the surface of the strong trousers, and the rubber plate is recessed. There is no or only slight friction with the sandpaper, basically retaining the original color of the denim fabric, while the protruding parts are directly rubbed, and the colored base layer on the surface of the friction area is destroyed, forming a slight white shadow effect. The standing whiskers are made by washing the strong woolen trousers, pressing out the required pattern with a high-temperature machine, spraying glue to set the shape, and drying them in a furnace. Therefore, the resulting whiskers are more solid and have strong stability. Not easily deformed.
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