Why does PVC Heat Shrink Film Shrink When it Encounters Heat?

21 Nov.,2022

 

pvc shrink film

Currently, Multi-purpose Shrink Film Manufacturers have developed shrink film technology that can be used to package a variety of goods. Protective properties of PVC heat shrinkable film packaging: During the production process, the PVC shrinkable film is directionally stretched, and the shrinkable film will be preheated during use. The PVC heat shrinkable film can be made into a cylindrical film or a folded film according to customer requirements. And the single film can also be processed into curved bags, flat bags, U-shaped bags, and other special-shaped bags. PVC shrink film is a Multi-purpose Shrink Film.

High Transparent PVC heat shrinkable film is a new type of packaging replacement product that has gradually risen and been accepted in recent years. Environmentally friendly co-extruded polyolefin PVC heat shrinkable film is a heat-shrinkable film with linear low-density polyethylene (LLDPE) as the intermediate layer and polypropylene (PP) as the inner and outer layers. It has the characteristics of high transparency, high shrinkage, and good heat-sealing performance. It also has the advantages of polyethylene (PE) and polybutene (PP), and its professional performance is far superior to pure polyethylene (PE) and polypropylene (PP) films. PVC heat shrinkable film has been widely used in the world and has been recognized by European and American markets.

PVC heat shrinkable film is a second blow molding made of ethylene PVC resin and more than 10 kinds of auxiliary materials. It has good transparency, easy shrinkage, and high strength. It is widely used indoors and windows, aluminum profiles, stainless steel tubes, electronic appliances, daily necessities, and crafts. , Building products, audio, and video products, medicine, stationery, toys, plastic hardware, glass ceramics, and other goods, outer packaging, make it more beautiful appearance, improve product packaging grade, and has dust, scratch resistance, insulation, and other functions. Is currently an ideal film packaging material.

Why does PVC heat shrink film shrink when exposed to heat? Do you also feel confused? Many people think that it is caused by thermal expansion and contraction. In fact, it is not true. Many people do not understand the real reason. So why do PVC heat shrinkable films shrink when they encounter heat?

In fact, the shrinkage of PVC heat shrinkable film after heating is a physical phenomenon, which needs some physical knowledge to explain. In short, it is the thermal movement of the molecules that causes the shrinkage of the PVC heat shrinkable film.

The macromolecules of ordinary plastic films are naturally curled and will not shrink when exposed to heat. The PVC heat shrinkable film is different. Its film formation has two steps. After the raw materials are melted, the film is stretched under the prescribed temperature and external force. The macromolecules cannot slide with each other and are frozen in an unnatural state.

At normal temperatures, the activity of plastic macromolecules is very poor, so we cannot rely on the movement of the molecules to eliminate this unnatural state, which is why PVC heat shrinkable films do not shrink at normal temperatures.

However, this is only a surface phenomenon, and the seemingly stable PVC heat shrinkable film actually has unstable factors hidden inside. When the PVC the heat-shrinkable film is reheated to a certain temperature, the frozen macromolecules start to move again and return to the natural state from the unnatural state, thereby causing shrinkage. The above is why the PVC heat shrinkable film will shrink after heating.

PCV Shrink Film