In general, special equipment is used for the extrusion biaxial stretching of plastic film. The film formed by plasticizing melt material of extruder is stretched longitudinally first and then horizontally so that the film blank is elongated and widened to meet the film thickness required by the process. The raw materials used for extrusion and stretch molding of plastic film include the use of special equipment to extrude the thickness of plasticized melt forest out of the machine, that is, double PVC, polypropylene, polyester, polystyrene, polyethylene and polyamide.

 

 

 

Biaxial stretching of polypropylene film is a kind of polypropylene sheet (flat film) or tubular film with a certain thickness, which is drawn along its longitudinal and horizontal directions (respectively or simultaneously) under the state of softening temperature and melting temperature, and then shaped. Because polypropylene resin is a kind of crystalline polymer, when it is stretched at suitable temperature, its molecules will be reoriented, so as to improve or improve the mechanical properties of polypropylene film. For example, compared with ordinary polypropylene film, the crystallinity tensile strength impact strength tear strength of biaxially stretched polypropylene film is better In addition, the cold resistance, heat resistance, air tightness, moisture resistance, glossiness and electrical insulation of biaxially oriented films are also improved compared with those of common polypropylene films (CPP).