The importance of surface treatment to the bonding strength of hot melt adhesives

The significance of surface treatment to the bonding strength of hot melt adhesives: The quality of surface treatment is often the key to determining the success or failure of a good adhesive joint. This is because the wettability of the adhesive to the surface of the adherend and the intermolecular forces at the interface (i.e., the adhesive force) are the main reasons for achieving high bonding strength. During the production, transportation, storage and use of parts, their surfaces will be contaminated to varying degrees, which directly affects the penetration of glue on them and the bonding strength. The importance of surface treatment also includes the following points.

① Before bonding, when preparing the surface of building components with hot melt adhesives, there are often oil stains, release agents, weathering layers, carbonization layers, rust layers, etc. These unclean and fragile surface layers should not be removed. It will greatly affect the bonding performance.

② Roughening the surface of the adherend can increase the actual bonding area of the adherend. For instance, sandblasting can increase the bonding area of polished metal surfaces by 20 times. In addition, a rough surface can enable the cured adhesive to form more interlocking structures with the adherend, that is, to generate mechanical adhesive force and enhance the bonding strength. This has been confirmed by both theory and practical experience.