The first time I saw children's shoes wrapped with film, I believe my first intuition is: "isn't this super large plastic wrap?" In fact, it is not. Although the materials of winding film and fresh-keeping film are similar, there are obvious differences in use, specification and production technology. Today I will tell you the difference between the two.

1. Different definitions

Winding film (tensile film and heat shrinkable film) is the first to produce PVC winding film in China with PVC as the base material, DOA as the plasticizer and self-adhesive. Due to environmental protection problems, high cost (relatively large proportion of PE, small unit packaging area), poor tensile property and other reasons, PE tensile film was phased out when it was produced in China from 1994 to 1995. PE stretch film first takes EVA as self-adhesive material, but it has high cost and taste. Later, PIB and VLDPE are developed as self-adhesive materials, and LLDPE is the main substrate, including C4, C6, C8 and Metallocene PE (MPE).

Preservative film is a kind of plastic packaging product, which is usually made by polymerization with ethylene as masterbatch. Preservative films can be divided into three categories: polyethylene PE, polyvinyl chloride PVC and polyvinylidene chloride PVDC. Among them, PVC fresh-keeping film contains carcinogens, which is harmful to human body. The generation cost of PVDC fresh-keeping film is too high, so PE fresh-keeping film is the most used in the market.

2. Different uses

Plastic wrap is generally used to wrap cooked food in the family, refrigerate in the refrigerator, preserve meat and protect small objects.

Winding packaging film is generally used for transportation packaging, such as winding packaging of large pallets, containers and boxes, as well as short-distance transportation and sales packaging, such as commodity packaging, winding packaging of stainless steel pipes, plastic pipes and profiles, winding packaging of plastic decorative plates, rolled floors, rolled carpets, etc. It is mainly used to prevent articles from scattering or scratching.

3. Different specifications

The thickness of the winding film is thicker than the fresh-keeping film, and the size is larger than the fresh-keeping film.

Household fresh-keeping film is generally large, with a width of 30cm and a thickness of about 10um; The general large-size width of industrial winding film is 50cm and the thickness is about 20um.

4. Different drawing ratio

The stretching degree of winding film is greater than that of fresh-keeping film. The winding film is directly blown by LDPE through blow molding machine, and its stretching ratio can reach 300% - 500%. At the same time, the fresh-keeping film is sticky to articles, while the winding film is self-adhesive, which is related to the amount of polyisobutylene used.