The invisible killer of hot melt adhesive durability


       Internal stress is one of the important factors of hot melt adhesive bonding failure, and internal stress is the manifestation of bonding failure, which is often very hidden. It is very likely that the cause of failure will not be found temporarily through the phenomenon. This failure directly affects the durability of the bonding. It is often the case that the bonding is confirmed to have been firmly bonded together, but after a few days, it is found that there is a crack or the interface is separated. To eliminate and slow down this phenomenon, improvements need to be made by relaxing the internal stress. The general methods are as follows:

1. Choose materials with low elastic modulus, small shrinkage, and small thermal expansion coefficient 

2. Increase the toughness of hot melt adhesive

3. Reduce cross-linking

4. Add appropriate amount of inorganic substances to stabilize the volume change

5. Reduce the temperature change rate of the curing process

6. Carry out post-curing treatment