With the rapid development of food, cosmetics, medicine, and other industries, the demand for plastic composite packaging products is increasing, and the quality requirements for plastic composite packaging products are also increasing. Packaging users not only focus on the aesthetics and logistics performance of packaging products but also the heat sealing strength of packaging products. Because the heat seal strength of the packaged product directly affects the packaging speed, transportation, and sales.

In actual production, all manufacturers, whether they are bag-making products or coil products used in automatic packaging production lines, control the heat seal strength as the most important quality index. The following combined with the actual production experience, a simple analysis of the factors that affect the heat seal strength of the heat shrinkable film:

  • 1. Heat sealing temperature: The heat sealing temperature directly affects the heat sealing strength of the plastic composite packaging product.
  • 2. Heat sealing time: The heat sealing time of automatic packaging machine or old-fashioned bag making machine is determined by the machine speed. In the case of constant heat sealing temperature and heat sealing pressure, the longer the heat sealing time, the stronger the bonding between the heat sealing layers. However, if the heat sealing time is too long, wrinkles and unevenness will occur in the heat sealing part of the composite film, which seriously affects the appearance quality of the product.

  • 3. Heat sealing pressure: To ensure the heat sealing strength of plastic composite flexible packaging, a certain heat sealing pressure is indispensable. Therefore, heat sealing pressure is required to be moderate and uniform during the heat sealing process. If the heat sealing pressure is insufficient or uneven, it will cause air bubbles in the heat sealing part and virtual welding, resulting in poor heat sealing.