Why is heat shrinkable packaging machine so popular? I think the most important reason is that the packaging equipment is fast, efficient, low cost and easy to operate. The product is easy to transport and sell. With the development of economy, heat-shrinkable packaging machines have been rapidly integrated into all walks of life. The choice of shrinkable film for heat-shrinkable packaging machine is also a problem that many people are struggling with.

During the normal operation of the heat-shrinkable packaging machine, the selection of the heat-shrinkable film material is very important. First, the film is required to have a certain shrinkage rate in both vertical and horizontal directions. The shrinkage rate=(L1 － L2)/L1 * 100%, L1 is the original length, and L2 is the shrinkage length after immersion in 120 ℃ glycerol for 1~2S and water cooling. According to the heat-shrinkable plastic film has the characteristics of heat recovery, when the film is made from raw materials. The shrinkage film is formed after heating and stretching in advance and cooling. When the film is reheated, it will shrink and recover.

Therefore, it is required that the film should have a shrinkage rate of about 50% in both vertical and horizontal directions, and have sufficient heat sealing strength, tensile strength, impact strength, tear strength, appropriate moisture resistance and oil resistance. At present, the most widely used shrinkable films include polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP), followed by polyvinylidene chloride (PVdc), polyester (PET), polystyrene (EPS), and ethylene-vinyl acetate copolymer (EVA).

The strength, transparency and elongation of heat-shrinkable plastic film are better than those of ordinary plastic film. When it is extended, if the appropriate temperature is given, the elongation of the film will increase to 1:4~1:7 before condensation, while the elongation of the ordinary film is only 1:2. There are two types of heat shrinkable film, one is biaxial type extended heat shrinkable film, and its vertical and horizontal axial extensions are almost equal.

The film can be used for packaging fresh food, food tray packaging and sealing packaging of container bottle mouth. The other type is an axial extended heat-shrinkable film, which only extends in one direction and is applicable to the shrink packaging and label packaging of tubular film, such as the label packaging of alcohol containers, the sealed packaging of plastic bottles, glass bottles and caps, and the sleeve packaging of fresh fruits and vegetables and other foods.