Why do stretch films need to be stretched before use?
Source：Mingye Packing Materials Co.,Ltd Release date：2021-01-28 Hits：2248
In our lives, we often see the use of stretch film to package items, the packaging of stretch film is very tight, enough to surface the good quality of the product. Generally, we must go through a stretching operation before using a stretch film for packaging. Many users do not understand why it is stretched. Today, the joypack stretch film manufacturer will introduce to you why the stretch film needs to be stretched before use.
1. The packaging of stretch film must be stretched. The stretch form of pallet mechanical packaging includes direct stretching and pre-stretching. There are two types of pre-stretching, one is roller pre-stretching, and the other is electric stretching. Direct drawing is completed between the tray and the drawing film. The drawing rate of this method is low, about 15%-20 %, if the stretch ratio exceeds 55%-60%, then the stretch of the stretched film will be exceeded, the width of the stretched film will be reduced, the perforation performance will also be lost, the stretched film is easy to break, and at 60% The tensile force is still very large at a stretching rate of, and for lightweight cargo, it is likely to deform the cargo.
2. The two-roller pre-stretching is linked by a gear mechanism, and the stretch ratio can be adjusted according to the gear ratio. The tensile force is generated by the turntable. Because the stretching is generated in a short distance, and the friction between the roller and the stretched film is large, the width of the stretched film does not shrink, and the original puncture performance of the stretched film is maintained. In, there is no stretching, which reduces the breakage caused by sharp corners. This pre-stretching can increase the stretch ratio to 110%.
3. The stretch film is a self-adhesive film, which is a single-sided or double-sided adhesive plastic film, which can stretch and wrap the package very tightly. The self-adhesive glue does not adhere to the surface of the package. Exist on the film and the surface of the film, with high tensile strength, high elongation, good self-adhesiveness and high transparency, widely used in export, bottle making, paper making, hardware and electrical appliances, plastics, chemicals, building materials, agricultural products, food, etc. industry.
In summary, the stretching needs to be pre-stretched before packaging the articles. This can not only improve the stretch performance of the stretch film, but also increase its puncture resistance and viscosity. If the stretch performance does not change, the packaging Some products are prone to insufficient tension problems. Some users will artificially buy stretch films that are unqualified, which indirectly affects the economic benefits of stretch film manufacturers. Therefore, pre-stretching must be done before packaging.
