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Why does the TPU hot melt adhesive film bubble during bonding?
The factors affecting the bonding effect of TPU hot melt adhesive film mainly include selection and operation. Common bonding problems include degumming, weak bonding, and blistering after bonding. Degumming and weak bonding can be a matter of choice. The bubbles after bonding are mainly caused by operational problems.
2022-05-05
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Why does the TPU hot melt adhesive film bubble during bonding?

The factors affecting the bonding effect of TPU hot melt adhesive film mainly include selection and operation. Common bonding problems include degumming, weak bonding, and blistering after bonding. Degumming and weak bonding can be a matter of choice. The bubbles after bonding are mainly caused by operational problems.

Whether it is bonded with TPU hot melt adhesive film or bonded with other hot melt adhesive film materials, the main reason for blistering is that the air cannot be discharged. This situation is very common in the application of films and impermeable product materials. Because films and air-impermeable product materials cannot remove accumulated air from the surface like non-woven materials can.

Therefore, when the TPU hot melt adhesive film is bonded to the substrate, if the entire surface is directly pressed, the air in the middle is likely to cause a backlog, and it is also likely to cause foaming after bonding. The solution to the blistering phenomenon caused by gas accumulation is to use a roller laminator or an iron to slowly heat the lamination material and TPU hot melt adhesive film from one side. In this way, the air in the middle can be continuously discharged through the surrounding, and there will be no accumulation of air and air bubbles after bonding.

In addition to the backlog of air that cannot be discharged, the reason for the foaming after the TPU hot melt adhesive film is bonded to the substrate is the foaming caused by secondary heating. This situation is common in materials and industries that require a secondary compounding process. Normally, the material does not foam when it is first bonded, but the TPU hot melt adhesive film will melt again after the second heating, which will cause the product to foam if a certain pressure is not given.

When using TPU hot melt adhesive film, you should also pay attention to the heating temperature. If the temperature is not suitable, it may cause the TPU hot melt adhesive film to "deteriorate". Simply put, if the bonding temperature of the TPU hot melt adhesive film is too high, it is likely to cause the TPU hot melt adhesive film to be "burned", and the temperature far exceeds the high temperature upper limit of the corresponding TPU hot melt adhesive film itself. In the process of using TPU hot melt adhesive film, the bonding temperature is a very important factor, because TPU hot melt adhesive film can melt and become sticky only under certain temperature conditions.

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TPU hot melt adhesive film vs anaerobic adhesive: "Scene flexibility" difference in automotive interior bonding
2025-09-11
​From the perspective of curing conditions, TPU hot melt adhesive film does not need to rely on special environments, while anaerobic adhesives are severely restricted by "auerobicity". The curing principle of anaerobic glue is to undergo polymerization under conditions of lack of oxygen and catalyzed by metal ions (such as iron and copper). If it is in an environment where air circulation or metal substrates are not available, the curing speed will be greatly slowed down or even unable to cure. In automotive interiors, most bonding scenarios are "open" (such as bonding the door panel skin to PP substrate, and the ceiling fabric to the sponge), the air can freely contact the bonding surface, and the substrate is mostly non-metallic (PP, ABS, fabric, etc.), lacking metal ion catalysis, and additional catalyst is required when using anaerobic glue, and the curing time is as long as several hours, which is difficult to meet the needs of industrial production. The TPU hot melt adhesive film only needs to be melted by heating (120-160℃) and can be cured after pressurization and cooling. It does not need to rely on the ambient oxygen concentration or the base material. It can be cured stably in open or closed bonding scenarios, and the curing time only takes a few dozen seconds to a few minutes, adapting to the fast-paced needs of the interior production line.
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