During the production process of the hot melt adhesive machine, air bubbles sometimes appear. What is the cause of the bubbles? The cause of the bubbles may be that the colloid itself has bubbles, there are bubbles after melting, or the colloid contains water, which is easy to generate bubbles when heated.
The other is that the hot melt adhesive is destroyed due to high temperature and decomposes to produce gas and bubbles. Therefore, why the hot melt adhesive decomposes due to high temperature depends on the composition of the hot melt adhesive, and then take SBC (thermoplastic elastomer hot melt adhesive) as an example.
This hot melt adhesive is composed of thermoplastic elastomers, plasticizers and resins. Resins and plasticizers are small molecules. There are many unsaturated bonds in the molecule. The molecular bond is unstable. When the heating temperature is too high, they will react with oxygen in the air.
It produces gases such as carbon dioxide, causing bubbles.