The most important function of packaging is to protect the quality of all packaged goods, that is, to ensure that the goods will not be damaged, lost, leaked and spoiled.
This requires that the seal must have a certain strength and sealing performance in the process of bag making, and can withstand the pressure of a certain weight of content to ensure that the product does not crack or leak during the circulation process, so as to achieve the purpose of protecting the product. And bag making is the last production process before delivery to users, and quality control is more important.
Most of the non-heat-sealable materials are used, and materials with good heat resistance and small thermal deformation should be considered, such as BOPA, BOPET, BOPP, paper, etc.
That is, the heat-sealable material can be heat-sealed at a temperature 30°C lower than the heat-deformation temperature of the surface-layer material. If the temperature is low, the sealing fastness is poor and cannot meet the requirements. In order to improve the sealing fastness, the temperature is raised. Because the thermal deformation temperature difference between the inner and outer layers is too small, the surface material is easily scalded.
For the same heat-sealing material, its heat-sealing strength will increase as the thickness of the heat-sealing material increases. Therefore, the inner layer material of the back sealing bag and the stand-up bag should be more than 30μm thick. If the inner layer material is too thin, it will affect the sealing of the finished bag.
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