The self-adhesive seal of mailing bags is mainly achieved by high-viscosity pressure-sensitive adhesive (self-adhesive adhesive). The adhesive layer is coated on the inner side of the bag flap and covered with a layer of peelable release paper (or release film). When in use, tear off the release paper and press the seal directly to bond.
1. Production process of self-adhesive seal
1.1 Gluing process: evenly apply pressure-sensitive adhesive on the bag flap area to ensure stable adhesion.
Release paper/release film covering: cover the adhesive layer with a layer of anti-adhesive release paper or release film to prevent the adhesive layer from sticking during transportation and storage.
1.2 Precise cutting and heat sealing: ensure that the sealing area is neat and the adhesive layer is intact to prevent leakage or uneven bonding.
2. Inspection method of self-adhesive seal quality
2.1 Adhesion strength test:
Tear off the release paper, press the bag mouth to seal, let it stand for a while, try to pull it open with force, and check whether it can be easily torn open.
The peeling force can be measured by a tensile tester, and the sealing peeling force is generally required to be ≥2.5N/cm (the specific standard can be adjusted according to customer needs).
2.2 High and low temperature adaptability test:
Put the sealed bag in high temperature (such as 60℃) and low temperature (such as -20℃) environments respectively to observe whether the viscosity is weakened or fails.
2.3 Durability test:
Perform multiple sealing-peeling cycle tests to check whether the adhesive layer still has good adhesion.
Storage stability test:
Put it under different humidity and storage conditions for a period of time to ensure that the release paper is easy to tear and the adhesive layer does not flow or solidify.
2.4 Anti-disassembly safety test (applicable to anti-counterfeiting or anti-tampering bags):
Once sealed, try to peel it off to see if the word "VOID" or other destructive marks are left to ensure that the anti-disassembly function is effective.
Ensuring the stable quality of the self-adhesive seal of the mailing bag will help improve the user experience, while ensuring the safety of package transportation and reducing the risk of disassembly.
