Synthetic fibers and blended fabrics have the smallest shrinkage, followed by wool, hemp and cotton fabrics, and silk fabrics have the largest shrinkage, while viscose, rayon and rayon fabrics have the largest shrinkage. Objectively speaking, all cotton fabrics have shrinkage and fading problems. The key is the finishing. Therefore, most of the home textile fabrics are pre-shrunk. It is worth noting that pre-shrinking treatment does not mean no shrinkage, but that the shrinkage rate is controlled within 3% - 4% of the national standard, especially the natural fiber clothing will shrink. Therefore, in addition to selecting the quality, color and pattern of the fabric, the shrinkage of the fabric should also be When you know something.
2、 Reasons for shrinkage:
(1) When the fiber is spinning, or the yarn is weaving, dyeing and finishing, the yarn fiber in the fabric is stretched or deformed by external force, and the yarn fiber and fabric structure produce internal stress. In the static dry relaxation state, or static wet relaxation state, or in the dynamic wet relaxation state, or full relaxation state, the release of different degrees of internal stress will restore the yarn fiber and fabric to the initial state.
(2) Different fibers and their fabrics have different degree of shrinkage, which mainly depends on the characteristics of their fibers - hydrophilic fibers have a large degree of shrinkage, such as cotton, hemp, viscose and other fibers; However, hydrophobic fibers have less shrinkage, such as synthetic fibers.
(3) When the fiber is in the wet state, it will expand under the action of the soaking solution, which will make the fiber diameter larger. For example, on the fabric, it will force the fiber curvature radius of the fabric weaving point to increase, resulting in the shortening of the fabric length. For example, cotton fiber expands under the action of water, the cross-sectional area increases by 40~50%, and the length increases by 1~2%, while synthetic fiber generally shrinks by about 5% due to heat, such as boiling water.
(4) When the textile fiber is heated, the shape and size of the fiber changes and shrinks, and it cannot return to the initial state after cooling, which is called fiber thermal shrinkage. The percentage of length before and after thermal shrinkage is called thermal shrinkage, which is generally expressed by the percentage of fiber length shrinkage in boiling water at 100 ℃; It can also be used to measure the percentage of shrinkage in hot air of more than 100 μ m, and it can also be used to measure the percentage of shrinkage in steam of more than 100 ℃. The performance of the fiber is also different under different conditions such as internal structure, heating temperature and time. For example, the boiling water shrinkage of the processed polyester staple fiber is 1%, the boiling water shrinkage of the vinylon is 5%, and the hot air shrinkage of the chloroprene fiber is 50%. There is a close relationship between fiber processing and the dimensional stability of the fabric, which provides some basis for the design of the subsequent process.
