Polyester film (PET) has excellent insulating properties, and it is easy to generate static electricity during the printing process and is not easy to see. In serious cases, the film may be adsorbed on the roller and cannot be printed. Therefore, when printing at high speed, it is necessary to set Static elimination equipment. The monotonic temperature of polyester film (PET) can be set higher, but its surface temperature should not exceed 850C. When winding, the film should be sufficiently cooled to room temperature to prevent ink sticking.

The transparency, heat resistance and printing operability of polypropylene film (PP) are better than polyethylene film (PE), and its ink adhesion is also poor. Surface treatment is required before printing to improve ink adhesion. The critical surface treatment is The surface tension should be controlled at 40-44mN/m.

BOPP film has small tensile deformation, is not easy to wrinkle, has good printing operability, excellent transparency and gloss, excellent moisture resistance, but poor heat sealability and tear resistance; CPP film has good heat sealability, but is easy to pull during printing The tensile deformation and heat sealability of the PP film are between BOPP film and CPP film, and the transparency and gloss are good. , but the thickness uniformity is worse than BOPP and CPP. It is suitable for front printing and can be used for packaging of textiles.

Polyvinyl chloride film (PVC) has good transparency, gloss and printability, generally does not require surface treatment before printing, and has excellent adhesion to ink. Its disadvantages are poor heat resistance and cold resistance, and it is toxic. Pay attention to its safety and hygiene. According to the amount of plasticizer, PVC film can be divided into three categories: rigid, semi-rigid and soft, and their functions are slightly different.

The soft polyvinyl chloride film is rich in many plasticizers, these plasticizers will separate into the printing ink layer, causing the disadvantages of discoloration, adhesion and ink moving, and it is easy to stretch and deform, causing wrinkles, resulting in poor overprinting. Accurate, so the tension control should be light. In addition, it is more likely to stretch when heated, making printing operations difficult. Soft PVC film has excellent self-adhesion when it is thin enough, and is often used in fruit and vegetable packaging.

General consideration of the tensile strength, moisture resistance, heat sealability and resistance of the salt package; impact strength needs, it is better to use CPP and HDPE as the inner film of the package, it has good heat sealability and can supply satisfactory. strength and moisture resistance. As an outer film, PLT and OPP with high strength, moisture resistance and low elongation are better. Considering the quotation factors, PVC is also a usable film for packaging outer film.