Chemical fiber is a kind of fiber with textile properties, which is made of natural polymer compounds or synthetic polymer compounds through the processes of preparing spinning dope, spinning and post-treatment. Chemical fibers can be divided into two categories: ① artificial fibers, such as viscose fibers and acetate fibers, are made of natural polymer chemical fiber spinning compounds (such as cellulose). (2) Synthetic fibers, chemical fibers made of synthetic polymer compounds, such as polyester fibers, polyamide fibers and polyacrylonitrile fibers. The advantages of chemical fiber are high strength, wear resistance, low density, good elasticity, no mildew, no fear of moth, easy washing and quick drying, but the disadvantages are poor dyeability, large static electricity, poor light and weather resistance and poor water absorption. Man-made fibers mainly include viscose fiber, nitric acid fiber, acetate fiber, cuprammonia fiber and man-made protein fiber, among which viscose fiber is divided into ordinary viscose fiber and new viscose fiber with outstanding performance (such as high wet modulus fiber, super viscose fiber and permanently curled viscose fiber). ). Synthetic fibers mainly include polyamide 6 fiber (called nylon or nylon 6 in China), polyacrylonitrile fiber (called acrylic fiber in China), polyester fiber (called polyester fiber in China), polypropylene fiber (called polypropylene fiber in China), polyvinyl formal fiber (called vinylon in China) and special fibers (including corrosion-resistant fibers polymerized by tetrafluoroethylene and high-temperature resistant fibers with the strength greater than1). In 1950s, the research on the modification of synthetic fibers was carried out, which mainly used physical or chemical methods to improve the properties of synthetic fibers such as moisture absorption, dyeing, antistatic, flame retardant, antifouling and pilling resistance, and at the same time increased the variety of chemical fibers.