Multilayer coextruded casting film can generally be divided into three layers: heat seal layer, support layer and corona layer. Compared with this, the development and application of CPE casting film production line in China started late, the foundation is relatively weak, and the introduction is mainly started. In the late 1970s, the introduction of single-layer salivating machines, mainly for the production of sanitary products films, began. After several years of development, the domestic casting machine has realized the historical leap from nothing to nothing, from single layer to multi-layer, from single variety to multi-variety, and has made great progress. According to incomplete statistics, as of 2006, China's CPP film production line has more than 77, with a production capacity of more than 390,000 tons; There are more than 150 domestic lines with a production capacity of more than 260,000 tons and a total production capacity of more than 650,000 tons. The imported equipment in the field of casting machine has occupied a leading position for a long time, and through continuous innovation, the domestic casting machine has greatly improved in mechanical structure and mechanical properties, and has been close to or begun to catch up with the international advanced level. With the increasing market demand at home and abroad, new plastic packaging materials, new processes, new technologies, new products continue to emerge. Casting film products and materials used are also constantly updated, China's casting machine professional manufacturers, in the brand, improve product quality and grade, and strive to catch up with the international advanced level at the same time, in order to avoid product homogenization, price war vicious competition, began to pay attention to the adjustment of product structure, as soon as possible to improve the technical content of existing products, and towards high performance, multi-functional, Actively adopt new raw materials, new technologies, expand application fields, and develop in the direction of coordinated development of plastic packaging and environmental protection. Develop new application areas of cast film, such as the development of new building materials for thermal insulation, heat insulation, waterproof, sound insulation for the construction industry cast film production line, conductive cast film production line for the electronics industry. And will be in the direction of high efficiency, energy saving, environmental protection, large, precision, multi-layer development. The production of CPE casting film includes single-layer casting and multi-layer co-extrusion casting