One of the important ways to improve the packaging level and the safety of the packaged goods by using modern technology is to make rational use of the heat shrinkable film packaging machine. Shrink wrap is a packaging method in which a product or package is wrapped with a heat shrinkable plastic film and then heated to shrink and wrap the article or package. The heat shrink packaging machine is characterized by rapid packaging, quick work efficiency, low cost, convenient operation, convenient transportation and sales of products, and is widely used in the food processing industry. With the development of the economy, the promotion of green food, heat shrink packaging machines have quickly integrated into all walks of life. The following is a brief introduction to how to choose a heat shrinkable film in a heat shrinkable package.

In the normal working process of heat shrink packaging machine, the selection of heat shrinkable film material is very important. Firstly, the film is required to have a certain shrinkage rate in both the longitudinal and transverse directions. The shrinkage rate = (L1-L2) / L1 * 100%, L1 is The original length, L2 is the shrinkage length after immersion of 1 to 2S in water at 120 ° C. According to the heat-reducible plastic film, the film is made of a raw material when it is subjected to heat recovery. The film is heated and stretched in advance, and is cooled to become a shrink film. When the film is reheated, it shrinks and recovers.

Therefore, the film is required to have a shrinkage ratio of about 50% in the longitudinal and lateral directions, and has sufficient heat seal strength and tensile strength, impact strength, tear strength, proper moisture resistance and oil resistance. At present, the shrink film used in many applications is polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP), followed by polyvinylidene chloride (pvdc), polyester (PET), polystyrene (EPS). ), ethylene-vinyl acetate copolymer (EVA) and the like.

The heat-shrinkable plastic film has better strength, transparency and elongation than ordinary plastic films. When the temperature is extended, the elongation of the film is increased to 1:4 to 1:7 before condensation, while the elongation of the ordinary film is only 1:2. There are two types of heat shrinkable films, one of which is a biaxial type extended heat shrinkable film, which has almost the same axial and lateral axial extension.

This film can be used to package fresh food, food tray packaging and container closures. The other type is a one-axis type extended heat shrinkable film that extends in only one direction and is suitable for shrink packaging and label packaging of tubular films, such as label packaging for wine containers, sealed packaging for plastic bottles, glass bottles and lids, fresh Casing packaging of foods such as fruits and vegetables.