Quality-related issue:
A certain proportion of packaging bags for quick-frozen foods is broken up at the bag body(instead of the seal) during the storage, transportation and sales process.

Cause analysis:
- Packaging materials

Poor cold resistance – Under low temperature, flexibility of the packaging materials will decline, the fragility increase and the impact resistance go down. In the anti-pendulum impact test for instance, anti-impact energy of the same material varies greatly as before and after the freezing.
Poor flexibility – Due to poor flexibility, low elongation rate and great stiffness of the packaging material under normal environment, certain internal pressure may cause resistance and thus breakage in the packaging material.

Expert suggestions:
- Check the tensile, elongation and elasticity modulus, pendulum impact energy, cold resistance, fall resistance and explosive pressure(positive pressure) of the packaging bags.
- Re-choose packaging materials of good flexibility and cold resistance, or improve quality of existing packaging bags