Characteristics of PVC heat shrinkable film packaging technology

Characteristics of PVC heat shrinkable film packaging technology

Shrinking films are usually produced by extrusion blow molding or extrusion tape casting, and then stretched longitudinally and transversely at a high elastic temperature above the softening temperature and below the melting temperature, or stretched only in one direction and not in the other direction. The former is called biaxial stretching shrinkage film, while the latter is called unidirectional shrinkage film. When in use, when it is higher than or close to the stretching temperature, it will shrink to wrap the packaged goods.

Factors of heat sealing strength of PVC heat shrinkable film

1. Heat sealing temperature: The heat sealing temperature directly affects the heat sealing strength of plastic composite packaging products.

2. Heat sealing time: The heat sealing time of automatic packaging machine or old bag-making machine is determined by the machine speed. When the heat sealing temperature and pressure are constant, the longer the heat sealing time, the stronger the combination between heat sealing layers. However, if the heat sealing time is too long, the heat sealing part of the composite film will be wrinkled and uneven, which will seriously affect the appearance quality of the product.

3, heat sealing pressure: for the heat sealing strength of plastic composite flexible packaging, the heat sealing pressure is yes. Therefore, the heat sealing pressure is required to be moderate and uniform in the heat sealing process. If the heat sealing pressure is not enough or uniform, bubbles will be generated in the heat sealing part, resulting in poor heat sealing.