Is PUR and EVA hot melt adhesive mixed? 3 misconceptions that make your glue pot useless and fail to bond

Can PUR and EVA be mixed?

Some manufacturers want to save time by using the same glue pot alternately for PUR and EVA adhesives, or by “mixing and complementing each other’s strengths and weaknesses”. These three misconceptions not only fail to increase efficiency, but also cause equipment damage and adhesive failure.

• Misconception 1: “Two types of glue can be heated, melted, and mixed togetherThe chemical systems of PUR (reactive polyurethane) and EVA (ethylene vinyl acetate) are completely different, and there is no synergistic effect after mixing. Instead, they interfere with each other – the adhesion decreases by more than 50%, and the adhesive layer shows phase separation and micropores.
• Misconception 2: “Changing the same glue pot is not a problem”When PUR is heated, it will undergo cross-linking reaction with moisture in the air, and the residual glue will form a non melting cross-linking network in the glue pot, blocking the rubber hose and valve. After cutting back the EVA, these PUR residues cannot be removed, and the accumulation becomes more severe. It must be a specialized pot.
• Misconception 3: “PUR devices can also use EVA freely”The PUR glue machine has a sealed and moisture-proof design, while the EVA equipment does not. Although EVA is technically feasible to operate in PUR equipment, it is necessary to thoroughly clean the rubber path during switching, otherwise PUR cross-linking residue will mix into the EVA adhesive solution.

Frequently Asked Questions (FAQ)

Q: What should I do if I want to apply PUR to an existing EVA glue pot?

A: PUR specific glue pot and glue supply system need to be purchased separately, and they cannot share pipelines. Sunlifehot melt adhesive pelletsThe EVA series and PUR series each have dedicated equipment solutions.

Q: Should we choose PUR or EVA for book and magazine packaging?

A: 90% of the book and magazine binding scenes are fully equipped with EVA, which has high cost-effectiveness. PUR is suitable for products with extremely high weather resistance requirements (such as archives stored outdoors for a long time), but it requires large equipment investment and complex operation.