The key to material selection
We all know that the function of the bag is to protect the quality of the packaged goods, that is to say, so that the goods in the transportation and sales of the entire circulation process, through different links, in different environments, are not damaged, leakage and deterioration. This requires the bag-making process must have a certain strength and sealing performance, to withstand the pressure of a certain weight of the contents, to ensure that the goods in circulation without cracking, without leakage, to achieve the purpose of protecting the goods. So below, let’s take a look at how quality bags to grasp the quality of bags.
- The choice of packaging bag surface material
To non-heat sealing materials for more, should consider the choice of heat resistance, heat deformation of small amount of material is appropriate, such as BOPA, BOPET, BOPP, paper, etc..
- The inner layer material selection
That is, heat sealing materials, to the surface layer of material heat deformation temperature 30 ℃ lower than the appropriate heat sealing, if the surface layer of material and heat sealing layer of material heat deformation temperature difference is too small, it will bring difficulties to the bag-making temperature control, because the temperature is low, sealing fastness is poor, can not meet the requirements, in order to improve the sealing fastness, the temperature will be increased, due to the heat deformation of the inner and outer layer of material temperature difference is too small, easy to the surface layer of material burns.
For the same heat sealing material, its heat sealing strength will increase as the thickness of the heat sealing material increases. Therefore, back-sealed bags, stand-up pouches and its inner layer of material should be more than 30μm thickness is appropriate, if the inner layer of material is too thin, it will affect the sealing of the finished bag.
The zipper seal should be selected with a lower heat sealing temperature, generally better than the inner material can be heat sealed temperature 5 ~ 10 ℃ lower, such as PE L-101 zipper seal heat sealing temperature than its PE LL-201 about 10 ℃ lower, can be selected for different PE inner material bag making, in order to achieve the best state of heat sealing with the inner material.
Control of process
The quality of finished products should be checked continuously during the production process. In addition to size and appearance visual inspection, sealing strength and sealing performance should be checked. Problems found in time to adjust, and make detailed records. Take the three-sided seal zipper bag making as an example, the following items should be checked.
- Heat sealing strength.
- Bag size, flatness, appearance quality, bag front and back alignment and other specified requirements of the customer, such as the location of the tear opening; zipper placement direction, especially in the zipper connection section.
- The internal and external opening force of the zipper, the internal opening force of PE zipper generally requires ≥ 50N/50mm, and the internal opening force of PP zipper generally requires ≥ 60N/50mm.
- The sealing performance of the bag, its detection can be used to add a dye penetration solution sprayed on the seal to see whether it penetrates or not, or use the bag with water hanging upside down for 24 hours to see whether it is water seepage method of inspection.
- The flatness of the bag zipper.