The shrinkage rate of fabric refers to the percentage of fabric shrinkage after washing or immersion in water. Generally speaking, the fabrics with the lowest shrinkage rate are synthetic fibers and their blended fabrics, followed by wool fabrics and linen fabrics, cotton fabrics are in the middle, with larger shrinkage, and the largest are viscose fibers, artificial cotton, and artificial wool fabrics. Next, Shanghai Qianshi will bring you relevant introductions.

 

　　The shrinkage rate of general fabrics:

 

Cotton 4%-10%; chemical fiber 4%-8%; cotton polyester 3. 5%-5 5%; natural white cloth is 3%; wool blue cloth is 3-4%; poplin is 3-4.5%; Floral cloth is 3-3.5%; card gabardine is 4-5.5; twill cloth is 4%; whistle is 3-4%; labor cloth is 10%; artificial cotton is 10%.

 

　　 Factors that cause fabric shrinkage:

 

　　① Different fabric materials have different shrinkage rates. Generally speaking, for fibers with high moisture absorption, after being immersed in water, the fibers expand, their diameter increases, their length decreases, and the shrinkage rate is large. If the water absorption rate of some viscose fibers is as high as 13%, and the synthetic fiber fabric has poor moisture absorption, its shrinkage rate is small.

 

　　②The density of the fabric is different, and the shrinkage rate is also different. If the density in the warp and weft directions is similar, the shrinkage rate in the warp and weft directions is also close. Fabrics with a high warp density will shrink in the warp direction. Conversely, fabrics with a weft density greater than the warp density will shrink in the weft direction.

 

　　③ Different fabric yarn counts have different shrinkage rates. The shrinkage rate of fabrics with thick yarn counts is large, and the shrinkage rate of fabrics with fine yarn counts is small.

 

　　④ Different fabric production processes have different shrinkage rates. Generally speaking, in the process of weaving, dyeing and finishing of the fabric, the fiber has to be stretched many times, and the processing time is long. The shrinkage rate of the fabric with greater applied tension is greater, and vice versa.

 

　　For general cotton fabrics, in the dyeing and finishing process, the warp direction is stretched and the weaving shrinkage is reduced. Therefore, the warp shrinkage rate is easy to understand. When the warp yarn is in a relatively straight state due to tensioning, the weft yarn is forced to increase the degree of bending to surround the warp yarn, causing the weft yarn to shrink and increase. Assuming that the length of the weft yarn remains unchanged, the width of the door will become narrower. Pulling it to the width of the finished product, this range is also unstable and will cause serious weft shrinkage. In order to reduce the weft shrinkage rate of the fabric, the mercerizing process of the fabric must be properly controlled so that the width of the mercerized fabric can be adapted to the width of the finished product. Of course, the warp tension of the fabric during the processing is reduced as much as possible. very important.

 

　　 Although the above discussion is only the shrinkage mechanism of cotton fabrics, in fact, other types of fabrics such as wool and silk also have similar shrinkage phenomena. Therefore, loose equipment is often used when processing wool and silk fabrics. However, the shrinkage mechanism of certain fiber fabrics has its special features. For example, viscose fiber has a short molecular chain and a large amount of amorphous part, so the wet modulus is small and it is easy to be elongated when wet. If it is kept stretched and dry, there will be a higher "dry setting, deformation, and re-wetting, due to the internal stress relaxation will cause greater shrinkage. Therefore, in the viscose fabric, due to the inner fiber The shrinkage caused by stress relaxation is an important factor in fabric shrinkage. For example, a certain stretched viscose yarn may shrink as much as 9-10% after wetting.