Polyurethane-hard foam composite, useful for making blocks and boards of high flame resistance, comprises hard foam particles and, as binder, isocyanate-containing prepolymer

摘要

Polyurethane-hard foam composite (A) comprises (a) 50-97.5wt.% polyurethane hard foam particles (P) and/or such particles of diameter 0.1-7.5 mm; (b) solid, isocyanate-containing prepolymer (PP), based on polyurethane solvolyzate that contains catalyst for the isocyanate reaction and optionally further additives and/or (c) other, N-containing powdered polymers and/or other additives. An independent claim is included for preparing (A) by subjecting a mixture of (i) (P) with (ii) isocyanate-containing oligourethanes, based on polyurethane solvolyzate, containing 5-15wt.% free isocyanate, solid at room temperature and containing catalysts, to pressure and temperature for 1-60 minutes.