Chemical fiber is a natural polymer compounds or synthetic polymer compounds as raw materials, after the preparation of spinning stock, spinning and post-processing and other processes to produce fibers with textile properties. Chemical fibers are divided into two categories: ① man-made fibers, natural high molecular chemical fiber spinning sub-compounds (such as cellulose) as raw materials made of chemical fibers, such as viscose fibers, vinyl ester fibers. ② synthetic fibers, synthetic polymer compounds as raw materials made of chemical fibers, such as polyester fiber, polyamide fiber, polyacrylonitrile fiber. Chemical fibers have high strength, wear resistance, low density, good elasticity, not moldy, not afraid of insects, easy to wash and quick drying, etc., but its shortcomings are poor dyeing, static electricity, poor light and weather resistance, poor water absorption. Synthetic fibers are mainly viscose fibers, nitrate fibers, acetate fibers, copper ammonium fibers and man-made protein fibers, etc., of which viscose fibers are divided into ordinary viscose fibers and new viscose fibers with outstanding performance (such as high wet modulus fiber, ultra-strong viscose fibers and permanently curled viscose fibers, etc.). Synthetic fibers are mainly polyamide 6 fiber (China said nylon or nylon 6), polyacrylonitrile fiber (China said acrylic), polyester fiber (China said polyester), polypropylene fibers (China said polypropylene), polyvinyl alcohol formaldehyde fibers (China said Velcro) as well as special fibers (including polymerization of polymerized tetrafluoroethylene made of corrosion-resistant fibers, high-temperature-resistant fibers resistant to temperatures of 200 ° C or more, strength greater than 10 g / denier, modulus greater than 200 g / denier). The modulus is greater than 200 g / dan of high strength, high modulus fiber, as well as flame retardant fibers, elastomer fibers, functional fibers, etc.). 1950s to carry out research on the modification of synthetic fibers, mainly physical or chemical methods to improve the synthetic fibers, moisture absorption, dyeing, antistatic, anti-flammable, anti-staining, anti-pilling, and other properties, and at the same time also increased the variety of chemical fibers.