Polypropylene, referred to as PP, is a polymer made of propylene by addition polymerization. White waxy material, transparent and light in appearance. The chemical formula is (C3H6)n, the density is 0.89 ~ 0.91g/cm3, flammable, the melting point is 164~170 ° C, the softening is about 155 ° C,
and the temperature range is -30 ~ 140 ° C. It can resist the corrosion of acid, alkali, salt solution and a variety of organic solvents below 80℃, and can decompose under high temperature and oxidation. Polypropylene is a thermoplastic synthetic resin with excellent performance. It is a colorless semi-transparent thermoplastic lightweight general plastic with chemical resistance, heat resistance, electrical insulation, high strength mechanical properties and good high wear resistance. It is widely used in the production of clothing, blankets and other fiber products, medical equipment, automobiles, bicycles, spare parts, transportation pipes, chemical containers and so on. It is also used for food and medicine packaging.