How to choose PA polyamide hot melt adhesive particles and EVA adhesive particles? Comparison of Six Indicators and Selection Suggestions

One sentence conclusion

For paper products such as book binding, cardboard box sealing, and quick printing of graphics and text, choose EVA for bonding Hot melt adhesive granulesOnly when the bonded parts need to withstand high temperatures above 80 ℃ for a long time, or when nylon, metal, or electronic components need to be bonded, do PA polyamide hot melt adhesive particles need to be applied. The price difference between the two can be two or three times. Using them in the wrong direction is not bad, but a waste of money.

First, distinguish what they are exactly

EVA hot melt adhesive granules are based on ethylene vinyl acetate copolymer, combined with thickening resin and wax, and are the most widely used category in the printing and packaging industry. PA hot melt adhesive particles (polyamide, also known as nylon hot melt adhesive or polyester amide hot melt adhesive) are formed by the condensation of dimer acids and polyamines, with amide bonds on the molecular chain. They have significantly stronger resistance to temperature and oil, and are commonly used in electronic sealing, automotive wiring harnesses, shoe materials, and special composites.

Horizontal comparison of six indicators

Why does the printing and packaging industry almost exclusively use EVA

The core requirements for paper product bonding are three: the adhesive should be able to quickly penetrate the paper fibers, the opening time should match the equipment speed, and the cost of a single book or box should be low. EVA is more suitable than PA in all three aspects. PA solidifies too quickly, and after the glue is applied, it forms a film before it can be folded, which can easily cause the spine to become weak and sticky; Moreover, PA’s high temperature resistance is not applicable to books, magazines, and cardboard boxes – books will not be placed in an environment of 100 ℃.

Under what circumstances should PA be considered

• Finished products need to be stored in high-temperature workshops, containers exposed to sunlight, or near heat sources for a long time, and EVA has softened and become sticky.
• The bonding objects include nylon cloth, plastic parts, and metal fasteners, such as sample books and folder hardware with plastic covers.
• Special packaging that requires resistance to oil stains or cleaning agents.

What should be done first instead of choosing materials

Many customers think that if they can’t stick firmly, they need to switch to a more expensive adhesive, but in fact, 80% of the problem lies in the process parameters: the melt adhesive temperature is 15 ℃ lower, the milling depth is not enough, the pressing time is too short, and the paper film is not treated with corona discharge. If these are not resolved, it will still open with PA. It is recommended to first perform a parameter calibration based on the existing EVA grade to confirm if it is truly temperature resistant or material mismatch, and then consider upgrading the adhesive type.

FAQ

Q: Can PA and EVA be mixed in the same glue pot?
Answer: No. The compatibility between the two is poor, and mixing them will result in delamination, black residue, and nozzle blockage. The glue must be thoroughly cleaned before changing.

Q: Do I have to change my PA when the exported books and magazines are exposed to 70 ℃ in the container?
Answer: Not necessarily. Try weather resistant or high softening point EVA first, which can solve the problem with limited cost increase and usually does not require crossing over to PA.

Selection suggestions

Guangzhou Sunlife TradingSunlife Hot Melt AdhesiveEVA adhesive particles are mainly used in three major scenarios: book binding, packaging and sealing, and quick printing of graphics and text. Different grades are available for side glue, back glue, sealing, and pasting boxes. The softening point and opening time can be matched according to the speed of the customer’s equipment; When encountering orders that require high temperature resistance, we can also cooperate with sample testing to finalize the plan. When selecting, informing the technology of the paper type, equipment model, workshop temperature, and finished product storage environment is much more accurate than just stating “to stick firmly”.