In the early 1940s, it gradually developed into a plastic shrink bag and quickly became the main packaging method of poultry (Turkey). At the same time, it developed a vacuum shrink bag that can prolong the storage life of fresh meat in cooperation with the pioneer manufacturers of meat packaging. So far, shrink packaging has been widely used by food manufacturing industry and food exporting countries, especially in the global cold and fresh meat industry, Shrink packaging has become a standard. The following is a brief description of the main functions of shrinkage:

1) Exquisite and not easy to fall off printing technology: cooperate with marketing and brand building;

2) High oxygen resistance: extend the storage life of products prone to oxidation and corruption;

3) High external force resistance: it can withstand the collision and friction of heat shrinkable gun during transportation and treatment. It is suitable for products with large packaging, bone or hard and rough surface;

4) Good sealing performance: sealing can overcome the pollution of blood, oil and gravy and increase the success rate of sealing. It is suitable for salted meat and all kinds of processed cooked meat products;

5) Cooking resistance: after packaging, the BOPP heat sealing film can be boiled below 100 ℃, and after cooling, it can be packaged, stored and transported, so as to reduce the chance of secondary pollution and increase the storage life;

6) Low temperature shrinkage: fresh pork will be scalded after thermal shrinkage due to different production quality. Low temperature shrinkage bags can have the same shrinkage effect as thermal shrinkage films in hot water 4 ~ 5 ℃ lower than the general shrinkage temperature. They are mostly used for export fresh pork;

7) Anti bone puncture: the packing bag developed for bone products can be placed according to the positi