Polyurethane (PU) is a high-molecular material with amino carboxylic acid bonds in its main chain, which is formed by the stepwise addition polymerization reaction of isocyanate and polyol. It can be regarded as the “magician of elasticity and hardness” - by flexibly adjusting the ratio and structure of the soft segment (long-chain polyol) and the hard segment (isocyanate and chain extender), it can continuously adjust the properties from soft elastomer to high-hardness plastic over a wide range. Therefore, it has excellent wear resistance, high elasticity, excellent oil and solvent resistance, low-temperature toughness, and outstanding adhesion. Polyurethane can be made into various forms such as foaming, casting, thermoplastic, and spraying through formulation adjustment, and can also be combined with fibers, metals, etc. It is widely used in various diverse occasions covering almost all fields of industry and civilian life, such as elastomers (industrial rollers, seals, tires), soft and hard foams (sofa mattresses, insulation boards, car seats), coatings (wood paint, car paint, waterproof coating), adhesives (shoe materials, building sealants), and synthetic leather (shoe uppers, clothing, luggage).