Analysis on the shrinkage rate of heat shrinkable film

At present, the heat shrinkable film used in packaging generally requires the shrinkage in both longitudinal and transverse directions to be equal, about 50% shrinkage; but in special cases, there are also unidirectional shrinkage, with a shrinkage rate of about 25% to 50%. There are also heat-shrinkable films with unequal shrinkage rates in the longitudinal and transverse directions. The ratio of the shrinkage rate in the longitudinal and transverse directions is called the shrinkage ratio.

PVC heat shrinkable film is a shrink film with unequal shrinkage rates in the longitudinal and transverse directions. The transverse shrinkage rate is 35%-45%, and the longitudinal shrinkage rate is 20%-25%. It is mainly used in aluminum alloy door and window packaging, aluminum Profile packaging, wooden door and interior door packaging, electrical appliances, stainless steel packaging, furniture, medical equipment, boxes and other outer packaging.

In the packaging operation, the shrink film starts to shrink when it reaches a certain temperature after being heated, and stops shrinking when the temperature rises to a certain height. The temperature in this range is called the shrink temperature.