Can the hot melt adhesive particles on the BOPP coated surface not stick? Avoid these 3 misconceptions and double the bonding to improve performance

Misconception 1: Increasing the amount of glue applied can make it stick

Many operators find that the BOPP film surface cannot stick, and their first reaction is to add glue. In fact, increasing the adhesive amount from 40g/m ² to 80g/m ² does not increase the bonding strength by less than 20%, but instead causes overflow, waste, and slow curing. The fundamental reason is that the surface energy of BOPP film is only 30-34mN/m,hot melt adhesiveUnable to infiltrate – it’s not a lack of glue, it’s glue that can’t hold on.

The correct approachReplace with low surface energy specialized hot melt adhesive particles containing thickening resin and polar modifier, which can increase the adhesion of BOPP film by more than 3 times.

Misconception 2: The higher the temperature, the stronger the adhesion

When the coating temperature was increased from 170 ° C to 200 ° C, the BOPP film wrinkled and deformed, and the adhesive liquid penetrated the film layer, causing delamination. High temperature does not equal high viscosity, exceeding the upper limit of material temperature resistance can have the opposite effect.

The correct approachThe coating temperature should be controlled at 170-180 ° C, and the opening time should be 3-5 seconds for the model to allow sufficient time for the adhesive to wet the film surface.

Misconception 3: The same model of rubber particle packaging dominates the world

Some factories use universal hot melt adhesive particles to simultaneously bond kraft paper, copperplate paper, and BOPP film, resulting in only the BOPP surface being opened. The surface energy of different materials varies greatly, and targeted selection is necessary.

The correct approachBOPP film surface is individually coated with adhesive. Sunlife hot melt adhesive has BOPP specific models, and Guangzhou Sunlife Trading provides free comparative testing services. One set of samples can verify the difference in effectiveness.

Frequently Asked Questions

• Q: Can the BOPP film surface be polished first and then glued?
  A: Okay. Corona treatment or light sanding with fine sandpaper can increase the surface energy from 32 to over 38mN/m, but the efficiency is low. For mass production, it is recommended to directly replace it with specialized rubber particles.
• Q: How much can the bonding strength be improved after replacing with specialized adhesive particles?
  A: The typical improvement is 2-4 times, ranging from “easily torn open by hand” to “paper cannot be torn open by adhesive”, depending on the film surface treatment status and pressing conditions.