Heat shrinkable film, commonly known as shrinkable film, is a film that can shrink greatly after heating, so it can tightly wrap articles and maintain its shape for a long time. The heat shrinkable film is designed based on the principle of tensile orientation of polymer molecular chain and formed by rapid cooling. The physical principle is: after the plastic raw material is heated and plasticized and extruded into the parent film, the polymer is forcibly stretched along the vertical and horizontal directions between the glass transition temperature and the drilling flow temperature, so that the molecular chain of the polymer is oriented along the stretching direction, and then the polymer is suddenly cooled, and the molecular orientation is frozen. When the film is reheated to the "thawing" temperature, due to the stress relaxation caused by molecular motion, the molecules return to their original state and shrink.

What are heat shrinkable films in life? Heat shrinkable films are things we rarely know but often contact. The coke, paper drinks and instant noodles we usually buy are packaged with heat shrinkable films. In addition, when we buy a mobile phone, we tear off the film outside the packaging box. The plastic packaging film industry has experienced more than 20 years of development in China, During this period, a certain scale has been formed. The heat shrinkable film industry occupies an important position in the packaging market and plays a positive role in promoting the national economy.