1. Polyethylene (PE), referred to as PE. It is a polymer organic compound made by addition polymerization of ethylene. Polyethylene is recognized as the best food contact material in the world. Non-toxic, tasteless and odorless, in line with food packaging hygiene standards. Polyethylene film, light and transparent, has the properties of moisture resistance, oxygen resistance, acid resistance, alkali resistance, general air tightness, excellent heat sealability, etc. Known as "the flower of plastic". It is the most important material for plastic packaging printing.
2. Polyvinyl chloride is abbreviated as PVC, and its molecular formula is (CH2-CH2CL) n, which is the most important type of vinyl polymer, and is the second largest plastic variety in the world after polyethylene. Domestic production ranks first among plastics. In the printing industry, PVC color calendered films and transparent glazing films are often used for packaging and decoration of covers such as books, periodicals, and tickets.
3. Shrinkfilm (Shrinkfilm) is a thermoplastic film that is stretched and oriented during the production process, and will shrink when subjected to hot air treatment or infrared radiation during use. After heat treatment, the film is tightly wrapped on the packaged object, the shrinkage force reaches the maximum during the cooling stage, and can be stored for a long time.
4. Low-density polyethylene, or LDPE for short, is the most widely used variety in the plastic packaging and printing industry in various countries. The specific gravity is 0.92 ～ 0.93, which can float in water. Low crystallinity (60%), bulk polymerization at a pressure of 1000-3000kg / C㎡, so it is also called high-pressure polyethylene. At 23 ° C, the density is around 0.92. The calendering formability is poor, and it is processed into a tubular film by the blow molding method. It is suitable for food packaging, fiber products packaging, daily chemical products packaging.
5. High-density polyethylene, referred to as HDPE. The density is 0.941 ~ 0.965g / cubic centimeter. Made with low-pressure polymerization, it is also called low-pressure polyethylene. Milky white, indicating a poor gloss. The film can be processed by blow molding and T-die extrusion process. It is heat-resistant and steam-resistant, cold-resistant and freeze-resistant. It has good moisture-proof, gas-proof and insulation properties, and is not easy to break. Very easy to open. Strong paper-like, known as "paper-like plastic film".
6. Biaxially stretched polypropylene film, also known as biaxially stretched polypropylene film, English abbreviation code BOPP, which is characterized by stretched molecular orientation, mechanical strength, half-fold strength, gas density, moisture barrier is better than ordinary plastic film . Compared with cellophane, the unit price is lower than cellophane. Due to the excellent transparency of this film, the color reproduction after printing is extremely bright and beautiful. It is an important substrate for plastic composite flexible packaging food bags.