In the packaging industry, packaging materials greatly affect the performance of packaging bags. Whether the packaging bags are well done or not, in addition to design, the structure of packaging bags and the materials used are also very important. CPP is one of the most common packaging materials. , what are its features and usage scenarios. Composite packaging bag, aluminum foil bag, plastic packaging bag (1) Universal type. Multi-layer co-extruded cast film (“CPP”) is designed with different co-extruded texture orientations for different purposes. It is because of the nature of this process. Excellent clarity and gloss are developed on the film by rapid cooling on chill rolls. Application scenarios For example, used for bread packaging, clothing packaging, porous fruit packaging, etc., or printed marketing copy, etc., composite BOPP/CPP two-layer film, used for clothing, dry food (such as fast food noodle bags, bowl lids, etc.) Package. A common type of CPP is co-PP/homo-PP/co-PP or homo-PP. (2) Metal type. The appearance of the product is required to have strong adhesion strength to vapor-deposited metal (such as aluminum), and it can still maintain good dimensional stability and rigidity after high-temperature cooking. In addition, it has lower heat sealing temperature and higher heat sealing strength. It can be combined with BOPP, BOPA and other substrates for high-quality packaging of tea, fried crispy food, biscuits, etc. (3) Cooking type. The two-layer copolymer CPP used for cooking can withstand cooking and sterilization at 120°C and 0.15MPa pressure, and has high air tightness. It not only ensures that the nutritional components and taste of the product will not be lost, but also improves the shelf life of the product. The film will not crack, peel or stick in a high temperature environment, and has good stability. It is often compounded with nylon film or polyester film. Packaged foods containing soup, meatballs, dumplings and other foods or frozen foods processed before eating. The retortable three-layer composite film structure is BOPET/AL/CPP, BOPA/AL/CPP. The structure of the single-layer cooking three-layer PP film is copolymerized PP/copolymerized PP/copolymerized PP. (4) High temperature cooking type. Packaging roast chicken, roast pork ribs, jam, and beverages requires three-layer copolymer CPP film with high temperature sterilization at 121~135 °C, of which the co-PP requires better performance than the ordinary cooking type. In addition to the three-layer film, there are also five-layer casting barrier packaging, whose structure is: PP/adhesive/PA/adhesive/copolymerized PE; PP/adhesive/PA/adhesive/EVA; PP/adhesive/ EVOH/adhesive/PE; PP/adhesive/EVOH/adhesive/EVA; PP/adhesive/EVOH/adhesive/PP, etc. CPP film for retort packaging should be made of copolymerized polypropylene or blended modified polypropylene pellets, not homopolypropylene. Since the CPP film made of homopolypropylene will be crispy after being cooked at high temperature, the seal is easily broken during the drop test, resulting in leakage of the contents. In addition, the limit temperature for the adhesion of the inner layer film is 110°C for medium density polyethylene, 120°C for polyethylene, 125°C for polypropylene, and 140°C for polypropylene in particular. Good material greatly affects the quality of the packaging bag. By matching with various materials, it can have various characteristics, making the range of use very wide.