How to choose hot melt adhesive for repairing broken lines in corrugated cardboard boxes? Key points for reinforcement and selection of conversion lines

Corrugated cardboard boxes are prone to cracking (commonly known as “bursting”) at the folding line position during logistics transportation. The common reinforcement method is to add a hot melt adhesive line to the folding line, and use the high elasticity and impact resistance of the adhesive layer to reinforce the weak point at the folding point. The key to choosing glue isElastic priority——Hard is actually more prone to cracking.

Why is the folding line of cardboard boxes prone to bursting

Breakthroughs are rarely caused by a single factor, and the three common types are:

• The conversion line is not reinforced.The folding point is the weakest point of the cardboard box, which relies solely on the surface paper itself to withstand bending.
• The adhesive layer is too brittle.If only a small amount of cold glue is used at the folding point, the glue layer will become brittle when exposed to low temperatures or long-term bumps, and this is the first place to crack.
• The adhesive layer is hard.Even if hot melt adhesive is used, if a high hardness formula is selected, the adhesive layer will harden after curing, and the cardboard will bend, causing stress to concentrate on the folding line and making it more prone to cracking.

Glue reinforcement plan

Add a diameter of approximately 1 at the position of the fold line; The mm hot melt adhesive line is pressed and formed, and then bent together with the cardboard. Key points: The glue line should be thin and uniform, adhere to the folded line, and be pressed in place. Compared to only applying cold glue during assembly, the hot melt glue line forms a flexible connection at the fold, dispersing the force.

Selection points (priority given to flexibility)

On the same device, the performance of different formulas on the conversion line varies greatly:

Conclusion: Folding line reinforcement should be selectedHigh elasticity and impact resistanceHot melt adhesive; Suggestions for actual selection based on cardboard weight, equipment and local climateFirst, make a sample to confirm。

Frequently Asked Questions (FAQ)

Q: Will the glue line affect the folding of the cardboard box?
Answer: It doesn’t affect. The high elasticity adhesive line has good flexibility after curing, and when folded, it bends with the cardboard without any hard resistance.

Q: Can the glue filling speed keep up with the packing line?
Answer: Hot melt adhesive solidifies quickly, and the adhesive repair process can be integrated into the automatic packing line, generally without the need for additional workstations.

Guangzhou Sunlife Trading provides hot melt adhesive products for the packaging industry, supporting sample selection based on cardboard and equipment.