Sewing thread is the thread needed for knitted products. According to the raw materials, sewing thread can be divided into three categories: natural fiber sewing thread, synthetic fiber sewing thread and mixed sewing thread. With the development of polyester industry, more and more pure polyester fibers are used as raw materials for sewing thread. Polyester fiber is a kind of synthetic fiber with excellent quality. The stitches made from polyester fiber are second only to nylon thread in all kinds of stitches, and the strength will not be reduced in wet state. Its shrinkage is very small, and the shrinkage is less than 1% after proper setting, so the stitches can always keep flat and beautiful without shrinkage. Wear resistance is second only to nylon. Low moisture regain, good resistance to high temperature, low temperature, light and water. Therefore, polyester thread is widely used in many occasions, replacing cotton sewing thread. Sewing thread polyester thread is widely used in sewing cotton, chemical and blended fabrics, as well as knitted garments. The special polyester line is also an excellent line for shoe and cap leather industry. Polyester sealing line can be used in fertilizer bag, cement bag, flour bag, feed bag, various woven bags, sole thread, inner wrapping line of water transmission pipe, etc.

The strength of cotton lining mainly depends on the length of cotton fiber and the number of twists. The longer the fiber length is, the larger the twist number is. The stronger the finished product is, the better the wear resistance is. The strength of cotton lining is better than that of man-made fiber, but worse than other fibers. The elasticity of elastic cotton fiber is poor, so the cotton lining is easy to wrinkle. Hygroscopic cotton fiber is a kind of porous material with large molecular content and hydrophilic structure, so it has good hygroscopicity and permeability, and the lining made of it is soft. Thermal insulation cotton fiber is a bad conductor with hot tears. The inner cavity of cotton fiber is filled with stagnant air. Therefore, the thermal insulation of cotton lining is good and the wearability is excellent. The dyeable cotton lining has good dyeing performance, bright color and complete chromatogram, which can match with all kinds of fabrics. Other properties of cotton lining have poor alkali resistance and acid resistance, good heat resistance and light resistance.