Polyurethane is a kind of better thermal insulation material in the world. It is a kind of polymer with - nhcoo - repeated structure unit on the main chain, abbreviated as PU. It is polymerized by isocyanate (monomer) and hydroxy compound. Due to its strong polarity and insoluble in non-polar groups, carbamate has good oil resistance, toughness, wear resistance, aging resistance and adhesion. Materials suitable for wide temperature range (- 50-150 ℃) can be prepared from different materials such as elastomer, thermoplastic resin and thermosetting resin, which are not resistant to high temperature hydrolysis and alkaline medium.

Polyurethane elastomers are used as rollers, conveyors, hoses, auto parts, soles, synthetic leather, wires and cables, and medical artificial organs. Soft foam is used for rigid foam in vehicles, rooms, clothing and insulation, sound absorption, packaging, heat insulation, low foaming synthetic wood, advanced automotive coatings, furniture, wood and metal protection, dams and building anti leakage materials, fabric coatings, etc. The adhesive has good adhesion to metal, glass, ceramics, leather, fiber, etc. polyurethane can also be made into emulsion, magnetic material and so on.

Polyurethane oil seal is mainly used for oil cylinder. It is easy to install and can scrape off the dust stuck on the piston rod. The green polyurethane oil seal has lower hardness, and the blue one has higher hardness, which can bear larger pressure. Polyurethane oil seal has good physical and mechanical properties, wear resistance and oil resistance. It is suitable for severe working conditions and can prevent the entry of external impurities, so as to achieve excellent sealing performance. It is a common seal in medium and high pressure hydraulic cylinder.