Practical experience of repairing adhesive on corrugated cardboard boxes with broken lines: the path of selecting hot melt adhesive particles from a return rate of 3% to 0.2%

The cardboard box has broken production lines and there are continuous returns

At the beginning of 2026, an e-commerce packaging factory in Shenzhen approached Guangzhou Sunlife Trading, stating that their corrugated cardboard boxes frequently had broken lines during logistics transportation (cracking at the folding points of the boxes), with a return rate of 3% and monthly losses of tens of thousands.

The Sunlife technical team found during on-site inspection that only a small amount of cold glue was applied to the folding line of the cardboard box during assembly, and the cold glue layer became brittle and cracked after logistics turbulence. Solution: Add at the fold line positionhot melt adhesive pelletsGlue repair line, utilizing the high elasticity and impact resistance of hot melt adhesive to reinforce weak points.

Selection process

I tried three models: high hardness type (with sufficient adhesion but easy to bend and crack), universal type (with generally good adhesion and bending), and high elasticity type (with excellent adhesion and bending). Finally, the Sunlife hot melt adhesive particle high elasticity special model was selected. A 1mm diameter adhesive wire was extruded at the folding line and pressed for 5 seconds to cure.

Actual test results: The pass rate of the drop test (1.2m) increased from 92% to 99.8%, and the return rate decreased from 3% to 0.2%. Adding glue to each box increases the cost by 0.03 yuan, which is much lower than the return loss.

Frequently Asked Questions (FAQ)

Q: Does the adhesive line affect the folding of cardboard boxes?

A: No impact. After curing, the high elasticity adhesive thread has good flexibility and does not crack when folded along with the cardboard.

Q: Can the glue filling speed keep up with the packing line?

A: Okay. Hot melt adhesive particles solidify in 5 seconds, and the adhesive repair process can be integrated into the automatic packing line without adding workstations.