Polyethylene (abbreviated PE), is a thermoplastic polymer consisting of long hydrocarbon chains. It is widely regarded as the world’s best material in contact with food since it is non-toxic, odorless, and tasteless which meets the hygienic standard for food packaging. Usually, polyethylene is transparent and has excellent chemical resistance, meaning that it is not attacked by strong acids or strong bases. It is also resistant to gentle oxidants and reducing agents. It can prevent water. As a result, it is the most widely used and important material in packaging and printing.

Polyvinyl chloride (abbreviated PVC), is a most important group of vinyl polymer, chemical formula is (-CH2-CHCL-) n. It is the third-most widely produced polymer, after polyethylene and polypropylene. In China, it ranks first in yield of various plastics. In printing industry, it is usually used as packaging and decoration of cover of books, folders, tickets and other things.

Shrink film,Shrink film is a thermoplastic film which is stretched in processing and will shrink if heat is applied. It shrinks tightly over whatever it is covering and exists in a long time.

Low-density polyethylene (abbreviated LDPE), is worldwide used in printing and packaging industry. It is suitable for food packaging, fiber products packaging and cosmetic packaging. LDPE is defined by a density range of 0.910–0.940 g/ cm3. Bulk polymerization takes at a range pressure of 1000～3000kg/cm2. It has a low crystallinity (60%) and poor calenderability. It can be processing into tubular film by blow molding.

High-density polyethylene (abbreviated HDPE), is defined by a density of greater or equal to 0.941 g/cm3. It cannot withstand high-pressure, so it is produced in low-pressure. In general, it is milky white and the surface gloss is poor. It can be produced by blow molding and T die extrusion process. It is resistant to high temperature and low temperature. It is not easy to break and twice the strength of LDPE. It is very easy to open it.

Biaxially Oriented Polypropylene (abbreviated BOPP) is a “heat-set” product (heat-setting is a process whereby a film is reheated in a constrained state such that the shrink properties are destroyed). The mechanical strength, bending strength, and barrier properties are better than ordinary plastic film. The price of BBOP is lower than cellophane in unit area. Because of excellent transparency, BOPP is an important backing material of soft plastic package.