Polyurethane (PU), full name of polyurethane, is a kind of macromolecular compound. It was made by Otto Bayer in 1937. Polyurethane is divided into polyester type and polyether type. They can be made into polyurethane plastic (mainly foam plastic), polyurethane fiber (called spandex in China), polyurethane rubber and elastomer. Soft polyurethane is mainly a thermoplastic linear structure, which has better stability, chemical resistance, resilience and mechanical properties than PVC foam materials, and has less compression deformation. Good heat insulation, sound insulation, shock resistance and anti-virus performance. Therefore, it is used as packaging, sound insulation and filtering materials. Rigid polyurethane plastic is light in weight, excellent in sound insulation and heat insulation, chemical resistance, good in electrical performance, easy to process, and low in water absorption. It is mainly used in construction, automobile, aviation industry and thermal insulation structural materials. The performance of polyurethane elastomer is between plastic and rubber, which is resistant to oil, abrasion, low temperature, aging, high hardness and elasticity. It is mainly used in footwear industry and medical industry. Polyurethane can also be used to make adhesives, coatings, synthetic leather, etc