Polyurethane structural adhesives (PUR)
Polyurethane adhesives are also part of the group of reactive adhesives and also addition-curing. The polymers offer a range of properties from low crosslinked (elastomers with high elongation at break) to strongly crosslinked (duromers). The use of polyurethane adhesives is virtually unlimited, depending on the pre-treatment of the substrates.
1-component polyurethane adhesives
The pasty prepolymers with terminal isocyanate groups, which crosslink to a high-strength and permanently elastic elastomer under the effect of sufficiently high humidity (40 to 70 %), are mostly used as adhesives for direct glazing or sealants in automotive engineering.
2-component polyurethane adhesives
The mostly low-viscosity isocyanate-terminated prepolymers and polyols harden by polyaddition to an elastomer or duromer within a period of a few hours to days, depending on the type. Temperature can accelerate curing and increase strength. They have stable mechanical properties over a wide temperature range.