Heat shrink film is a common packaging film, heat shrink film can be divided into two categories, barrier shrink film and non-barrier shrink film, non-blocking shrink film has a lot of classification. According to the raw materials and process, there are four categories (PVC heat shrink film, PE shrink film, POF shrink film, other shrinkfilm).
PVC heat shrink film features
PVC heat shrink film is one of the longest shrink films in history. It is produced using PVC through a double bubble process that blows twice. PVC thermal shrink film has the characteristics of high transparency, high stiffness and low shrinkage temperature. In recent years, POF shrink film in the field of display packaging occupied a large number of PVC heat shrink film market. However, in the shrink bottle label market, relying on low-cost, high shrinkage ratio, easy to print characteristics, PVC thermal shrink film still occupies the majority of the market share.
PE heat shrink film features
PE heat shrink film is another long-standing shrink film. As the name implies, PE heat shrink film is a heat shrink film produced with polyethylene as raw material. Unlike PVC shrink films, PE shrink films are produced by a common blowing membrane process. Due to the high processing temperature (far above the polyethylene melting point), low-density polyethylene (LDPE) containing a large number of long branch chain structures is generally used as raw materials for production.
In order to get enough lateral shrinkage of the film. In recent years, with the development of catalyst technology and polymerization process, some new polyethylene and linear low density polyethylene can also provide better lateral shrinkage performance while providing excellent mechanical properties. As a result, there are a large number of high-transparent, high-strength PE shrink film on the market.
POF heat shrink film features
POF shrink film has developed very rapidly in recent years. The ordinary POF shrink film is a three-layer co-extrusion structure of the ter-PP surface and the linear low density polyethylene (LLDPE) core layer. Similar to PVC heat shrink film, POF shrink film is also produced by double foam. Because the second membrane bubble is not easy to stabilize, the demand for linear low density polyethylene in the formulation is very high. Cross-linking membrane is a high-end product in POF shrink film. Unlike ordinary POF membranes, cross-linked membranes are pure PE structures.
The production process is also slightly different from the ordinary double bubble method, when producing cross-linked membrane, it is necessary to cross-link PE membrane bubbles with electron beam irradiation before the second membrane bubble. Compared with ordinary POF membranes, cross-linked membranes have better shrinkage and heat sealing properties, and can adapt to different packaging machines and contents. Coupled with the production process is complex, difficult, the added value is much higher than ordinary POF membrane.