Polyurethane abbreviation. The main chain of the polymer contains a repeating -HNCO-O- group-based resin, usually consisting of polyisocyanates, polyol polymers or aromatic diamines, and the like. As the polyurethane contains a strong polar carbamate group, adjust the formula NCO / OH ratio, can be made thermosetting polyurethane and thermoplastic polyurethane different products. According to their molecular structure can be divided into two kinds of linear and body. Body structure due to different cross-linking density, can show hard, soft or between the two properties, with high strength, high wear resistance and solvent resistance and so on.