The main characteristics of plastics are: first, low density, high specific strength, and high packaging rate, that is, "packaging volume per unit mass or packaging area size. Second, most plastics have good chemical resistance, good acid resistance, alkali resistance, resistance to various types of organic solvents, long-term placement, no oxidation. Third, easy to form, the required energy consumption for molding is lower than steel and other metal materials. Fourth, it has good transparency and easy coloring.