What Is The Function Of Polyolefin Film?
What is the function of Polyolefin Film?
Polyolefin film made of polyvinyl chloride, polyethylene, polypropylene, polystyrene and other resins are used for packaging and as a coating layer. The share of plastic packaging and plastic packaging products in the market is increasing, especially composite plastic flexible packaging, has been widely used in food, medicine, chemical and other fields, and in which the largest proportion of food packaging, such as beverage packaging , frozen food packaging, cooking food packaging, fast food packaging, etc., these products have brought great convenience to people's lives.
The surface tension of the polyolefin film depends on the surface free energy of the polyolefin film, and the surface energy of the film depends on the molecular structure of the film material itself. Most plastic films such as polyolefin films (LDPE, HDPE, LLDPE, PP) are non-polar polymers, have a small surface free energy and a low surface wet tension, typically about 30 dyne/cm. In theory, if the surface tension of the object is lower than 33 dyne/cm, ordinary inks or adhesives cannot adhere firmly, so they must be treated on the surface. Polyesters (PET, PBT, PEN, PETG) are polar polymers with a high surface free energy and a surface wet tension of 40 dyne/cm or more. However, for high-speed color printing or for increasing the bonding force between the vacuum aluminizing layer and the BOPET film surface, it is also necessary to perform surface treatment on the BOPET film to further increase the surface wet tension.