Polymer materials are classified into natural, semi-synthetic (modified natural polymer materials) and synthetic polymer materials by source. Natural polymers are the basis of the origin and evolution of life. From the very beginning, human society used natural polymer materials as living materials and production materials, and mastered its processing technology. For example, silk, cotton, and wool are woven into fabrics, and wood, cotton, and hemp paper are used. In the late 1930s, it entered the stage of chemical modification of natural polymers, and semi-synthetic polymer materials appeared. In 1870, the American celluloid plastic made by American Hyatt using nitrocellulose and camphor was an epoch-making artificial polymer material. High syntheticity appeared in 1907 The rubber molecule phenolic resin truly marks the beginning of a purposeful synthetic polymer material for human application of chemical synthesis methods. In 1953, German scientist Zieglar and Italian scientist Natta invented a coordination polymerization catalyst, which greatly expanded the raw material source of synthetic polymer materials, and obtained a large number of new synthetic polymer materials such as polyethylene and polypropylene. General synthetic polymer materials have left thousands of households and established synthetic polymer materials as a symbol of the development stage of contemporary human social civilization. Modern, polymer materials have been the same as metal materials and inorganic non-metal materials, and have become important materials in science and technology and economic construction. Prepainted Galvalume Steel Coils,Aluminum Zinc Coated Steel,Zinc Plated Steel,Galvanized Steel Sheet Comat Metal Products Co., Ltd. , http://www.china-tinplate.com