PVC heat shrinkage after heating is a physical phenomenon, need to be explained by certain physical knowledge, simply put, the thermal movement of molecules makes PVC heat shrinkage film.
The macromolecules of ordinary plastic film are in a naturally curled state, and generally do not shrink when heated. The situation of PVC heat shrinkable film is different, the film has undergone two steps, the raw material is melted at the specified temperature and stretched under the action of external force, the macromolecules can not slip from each other, and the unnatural state is frozen.
When the PVC heat shrinkable film is reheated to a certain temperature, its frozen macromolecules will start to move again, trying to return to the natural state from an unnatural state, resulting in shrinkage.
Extended Information:
Precautions for PVC heat shrinkable film production:
1. The die of PVC heat shrinkable film must be cleaned, and no charred plastic can fall in, and if it can be found by the naked eye, it must be removed immediately.
2. The paper tube must be right, not long and short.
3. When packing, pay attention not to collision, resulting in quality problems such as edge cracking.
4. Minimize the appearance of surface wrinkles and white pressing lines in the middle, so as not to affect the beauty.
5. The edge material should be cut neatly, and the uneven stretch film cannot be shipped as a finished product.
