Polyurethanes come as two-part systems or one-part moisture-curing pastes. They bond plastics, composites, wood and glass with good peel and impact and stay flexible at low temperature, which suits panels, automotive glass and dissimilar materials that expand at different rates. Isocyanates react with water too, so damp surfaces or high humidity can foam the bondline with carbon dioxide bubbles.
Windshield goes in with the one-part urethane, then no driving the van until the safe drive-away time.
Also heard as
- urethane
- PU adhesive
Related terms
Moisture cure
A cure triggered by humidity in the air or on the parts, used by silicones, urethanes and silane polymers.
PUR
Polyurethane reactive hot melt, applied molten like a hot melt, then moisture-cured into a heat-resistant bond.
MS polymer
A silane-modified polymer that moisture-cures into a flexible, paintable, isocyanate-free adhesive-sealant.
Two-part
Describing an adhesive supplied as a resin and a hardener that start curing only once mixed.