Main plastic film substrates for composite films 2

(7) Cellophane is mainly used as the outer layer and middle layer in the composite film. It has good oxygen barrier, good rigidity, high transparency, good gloss, good stiffness, no static electricity, large polarity, good printability, excellent oil resistance, no yellowing due to light exposure, good heat resistance, and twisting resistance, but its moisture resistance is poor, so moisture prevention treatment or polyvinylidene oxide coating should be carried out before composite to improve moisture resistance and gas barrier.

(8) EVOH film includes both stretched and unstretched films. Unstretched EVOH is often used as the intermediate layer of the composite film. Biaxially stretched EVOH film has high tensile strength, impact strength, sharp resistance, transparency, excellent barrier properties, and good fragrance retention. As a base film, it is one of the high barrier materials in food and drug packaging.

EVOH film is a thin substrate with high barrier properties, which is not widely used in China due to the high cost of resin

(9) The main characteristics of polyvinyl alcohol film are its strong toughness, excellent mechanical properties, transparency, and high barrier to other gases in addition to high water vapor permeability. After being coated with polyvinylidene chloride, it improves moisture resistance and high barrier to water and gas. After being combined with heat sealing film, it forms a composite film material with high barrier and good fragrance retention

Polyvinyl alcohol is one of the high gas barrier materials, and its application still needs further development.

(10) EVA film is mainly used as a heat sealing inner layer in composite films. It has better low-temperature heat sealing performance, puncture resistance, cold resistance, softness, and impact resistance than polyethylene and polypropylene heat sealing layers, and is also one of the commonly used heat sealing inner layers

(11) Vacuum aluminum plating film is a vacuum aluminum plating film based on biaxially stretched polyester film, biaxially stretched polypropylene film, cast polypropylene film, polyethylene film, polyvinyl chloride film, etc. In addition to the properties of the base film, it also has a beautiful appearance, decorative properties, and high barrier properties. Compared with aluminum foil, it has excellent resistance to bending and cracking, but bending, rubbing, and other factors can cause the plating to fall off, resulting in a significant decrease in performance.