Made of polyethylene film process

Low-density polyethylene films are generally made by blow molding and casting processes. The thickness of cast polyethylene film is uniform, but because of the higher price and lower cost, it is the most widely used. Low-density polyethylene film is a semi-transparent, shiny, and soft film with excellent chemical stability, heat-sealability, water resistance and moisture resistance, freezing resistance, and boiling. Its main disadvantage is its poor barrier to oxygen. It is often used in the inner film of composite flexible packaging materials. It is also the most widely used and most used plastic packaging film, accounting for more than 40% of the consumption of plastic packaging films.

Since the polyethylene molecule does not contain polar groups, has high crystallinity and low surface free energy, the film has poor printing performance and poor adhesion to inks and adhesives, so it is necessary before printing and lamination Perform surface treatment. Polyester film is a film material made of polyethylene terephthalate as a raw material, made into thick sheets by extrusion, and then biaxially stretched. It is a colorless, transparent, glossy film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high and low temperature resistance, chemical resistance, oil resistance, air tightness and fragrance retention Good, one of the commonly used barrier composite film substrates. However, the price of polyester film is relatively high, and the thickness is generally 12 μm. It is often used as the outer layer material of retort packaging, and has better printability.