Jeans with its rugged texture, nostalgic style, wear - resistant, crisp, comfortable unique charm and enduring, not in its style and production process changes, but in the ever-changing finishing process. In order to get the unique appearance effect of jeans, we must use stone mill, snowflake mill, enzyme mill wash, sand wash and other processes to wash the old jeans.
The finishing process of washing water is the key process to make jeans obtain unique style. among the factors affecting the washing effect of jeans, the following factors are analyzed and discussed from the aspects of additives, ph value and bath ratio.
First, the influence of additives on jeans washing effect
In the washing process of jeans, additives play an important role in the washing effect. Denim fabric generally belongs to pure cotton fabric, through chemical or physical additives and fabric surface fibers or dyes have a certain effect, coupled with a certain mechanical external force, on the surface of the cotton fabric fibers have a certain degree of wear and tear, or eliminate part of the dye pigments in the cotton fabric, so as to achieve a certain wear fade effect.
1. the influence of additives on the stone grinding effect of jeans
1.1 ordinary stone grinding finishing mechanism
Stone grinding is to put pumice containing sodium hypochlorite and jeans which have been desized in advance into an industrial washing machine for stone grinding treatment. By the interaction between pumice and jeans, jeans and jeans friction, and washing machine drum machine wall, partially grinding off the dye on the surface of jeans, at the same time will produce a lot of ash powder containing sodium hypochlorite. Visible, stone mill wash the main chemical assistant is sodium hypochlorite, because it is a strong oxidant, can destroy the indigo or sulfide melanin on cowboy clothing, played a certain role in stripping bleaching. Because of the different weight of the ash powder on the clothing, very uneven, so decolorization, white form, how much, size is also irregular.
1.2 snow grinding finishing mechanism
Snowflake mill belongs to stone mill wash, its process principle and ordinary stone mill is roughly the same, the main difference lies in the selection of chemical additives. Sodium hypochlorite is usually used as strong oxidant in common stone mill, while potassium permanganate is used in snowflake mill. In addition to removing the dye on the surface by the friction between pumice, jeans and the drum-type machine wall of the washing machine, oxygen is mainly released through the reduction of the potassium permanganate solution in the pumice to generate strong oxidation on the pigment so as to uniformly decolor the pigment and achieve the uniform snowflake shape effect. Snow mill wash pumice particle size and shape should be similar, generally round, like egg size is preferred. The pumice washed by ordinary stone mill is usually 1 - 2 cm in size, and the size is different, thus forming an irregular white snowflake effect. And the indigo jeans after snowflake grinding, its appearance white surface is wide, and white whiteness is more white, blue white surface contrast is bigger, unlike stone white more uniform, blue white contrast is small, and snowflake grinding the white place, like a lot of snowflakes, is full of trousers, there is a " blue sky white clouds" natural romantic style.
2. the influence of additives on the sandblasting effect of jeans
Sand blasting raw materials are carborundum and potassium permanganate, both are using high pressure spray to the fixed parts of jeans, generally in the front and back of the thigh and buttocks, make the surface color becomes shallow, achieve a grinding effect. The former is called sand blasting, the latter is called spray ma Qian. Due to the different raw materials used, the fading reaction of different properties occurs, which leads to the difference of washing water effect.
Sand blasting and horse-drawn blasting are carried out before desizing water. Sand blasting is to use compressed air as power, through the spray gun, high kinetic energy of angular carborundum material is sprayed to a certain part of jeans, sand material on the surface of jeans have a strong impact, causing the surface pigment off, so as to achieve a fading effect. It can be seen that sand blasting mainly takes carborundum as raw material, which makes denim fabric fade by physical action. Spray horse is the use of spray gun potassium permanganate or sodium hypochlorite and other chemical solvents, the fixed parts of jeans, such as hip spray. Potassium permanganate droplets are evenly distributed on the surface of denim fabric, causing the fabric to fade due to chemical reaction. The mechanical impact force of sand blasting makes the slurry layer of jeans fabric loose or split, so as to achieve the effect of softness and looseness. Therefore, sandblasting causes physical damage to the surface layer of the fabric, only has a fading effect on the surface layer, and has no layered feeling. The horsetail is sprayed with potassium permanganate as an auxiliary agent and has a strong oxidation effect on the pigment of the denim fabric, so that the horsetail can achieve a strong fading effect, has uniform fading, has fading in the inner layer of the surface layer and has layering feeling.
Second, bath ratio, temperature on jeans washing effect
Jeans washing process is mostly based on a series of complex chemical reactions. different control of temperature and solvent amount will have different effects on washing effect. The bath ratio is the weight ratio of the fabric to be washed to the auxiliary agent, which is used to represent the amount of auxiliary agent in dyeing and finishing specialty. Taking the enzymatic washing process as an example, the effects of temperature and bath ratio on the enzymatic washing were analyzed.
1. enzyme washing mechanism of jeans
Cellulase is used as the main chemical aid in enzyme washing, and can be divided into den IMAX enzyme ( neutral cellulase ) and den IMAX acid enzyme ( acidic cellulase ) according to the suitable ph value of the enzyme. Jeans are usually cotton fabric, cotton fabric is composed of cellulose fibers. Enzyme washing is to use cellulase hydrolysis reaction of cellulose fiber, make the denim fabric surface part of the fiber dissolved, indigo, vulcanization, reduction and other dyes also with the help of washing equipment friction and kneading effect, so as to achieve the effect of " wear old feeling". After enzyme washing, the fabric has little strength loss, bright and clean surface, unique and bright appearance effect, and the softness, drapability, water absorption and the like of the fabric are also improved.
2. the effect of bath ratio and temperature on enzyme washing
Bath ratio is a key factor in the enzymatic cleaning process of jeans. The bath ratio is too small, so that the fabric with too little liquid, uneven friction, affect the enzyme washing effect; The bath ratio is too large, the amount of enzyme is large, the cost is increased, the amount of liquid makes the fabric easy to float on the liquid surface, the mutual contact with the enzyme is not tight, the friction is not sufficient, and the fabric can be greatly damaged, so that the strength of the jeans fabric after enzyme washing is reduced. For common denim, bath ratio is generally controlled at 1: 10 - 15. For heavy, wear-resistant jeans, a small amount of pumice can be added to the cellulase treatment, which can improve the enzyme washing efficiency and produce a unique stone white style. In addition, the activity of the enzyme can be kept optimal only under certain temperature conditions, and if the temperature is too high or too low, the activity of the enzyme can be reduced or even lost, so that the hydrolysis reaction of the enzyme is insufficient, and the final fading effect cannot be achieved. In general, cellulase has the best activity when the temperature is 40 ℃ - 60 ℃. For example, the optimum reaction temperature of acid enzyme is 55 ℃, 65 ℃ will make the enzyme inactive, 30 ℃ will make the enzyme performance is reduced. It can be seen that temperature and bath ratio have important influence on enzyme washing effect.
Third, the influence of ph value and time on the washing effect of jeans
Indigo dye suspended in aqueous solution will show a strong tendency to stick back on the surface of jeans garment during the enzymatic scouring process, and the sewing rule and inner pocket of garment will turn blue. This tendency mainly depends on the ph value of water bath, ph below 6 has obvious phenomenon of back - dip. Can be removed by light bleaching of sodium hypochlorite or hydrogen peroxide. Acid enzyme activity is higher, has a high degree of erosion on cellulose fiber, on cotton fabric strength loss is big, but in a short period of time can be completed wear, acid enzyme washing time is generally controlled in 45 - 90 min. Neutral enzyme activity is low, the erosion of cellulose fiber is weaker than acid enzyme, the loss of fabric strength is small, but neutral enzyme washing time is longer, generally controlled in 60 - 120 min.
Four, the influence of other factors on jeans washing effect
In addition to the above factors have an important impact on jeans washing effect, there are other factors such as different process operation equipment will also lead to differences in washing effect. Such as the two are also after cat whisker finishing, but presents a different style effect. One is a strips of cat whisker pattern, showing a white shadow effect, while the other cat whisker pattern is honeycomb, stereo feeling is very strong, than the former has a hierarchical sense.
This difference is mainly due to differences in operating equipment and tools. The former said hand wipe cat whiskers, mainly by hand, first put the need to hand wipe the parts on the rubber plate engraved with convex and concave cat whisker shape, and then manually with sandpaper on the surface of jeans friction, rubber plate concave place did not occur or only slight friction with sandpaper, basic retain denim primary colors, and the protruding part is directly friction, friction on the surface of the dyeing base was destroyed, formed a slight white shadow effect. The three-dimensional cat whiskers are formed by washing jeans with water, pressing out required patterns by a high-temperature machine, spraying glue for shaping, and drying by a fan furnace, so that the generated cat whiskers are more three-dimensional in shape, strong in stability and difficult to deform.