Protective film is a plastic film used for packaging, generally divided into single-layer and double-layer. A double-layer protective film is made by bonding two plastic films together, usually consisting of an inner layer, a middle layer, and an outer layer.

Common materials for double-layer protective films include PET, PP, and PE, among which PET material is widely used. The protective film of PET has the advantages of high transparency and strong toughness; The protective film of PP has the characteristic of low price; The protective film of PE is slightly inferior in toughness compared to the first two materials, but its transparency is very high.