Лако-красочные материалы — производство

The gap between the parts and therefore the thickness of the adhesive film has an important bearing on the characteristics of the joint [4]. A thick bond line (>0.25 mm) will generally be a weakening feature for cyanoacrylates as the mechanical strength of the cured cyanoacrylate film is likely to be less than the plastic or other substrate bonded. For most applications where cyanoacrylates are involved, thin films (<0.05 mm) often give the best results. UV adhesives will fill gaps of several millimetres and this can be beneficial if parts are poorly fitting or if wide tolerances exist, however a thin joint line (<0.1 mm) will usually give the strongest joint. Where high peel or cleavage loads exist, a thicker bond line with a flexible or toughened adhesive can reduce the higher stress concentrations and thus increase the peel load.

Epoxies, polyurethanes, two-part acrylics and the adhesive/sealant products (silicones, and modified silanes) all have excellent gap-filling capabilities and some of these products will offer excellent resistance to impact loading and peel loads.

Assemblies with varying joint gaps should be avoided as much as possible. This practice will avoid uneven stress distributions, irregular pressures in the assembly and internal curing stresses.