Process for the Production of CFC-Free Hard Polyurethane Cell Plastics with a Reduced Heat Conductivity and Their Use

摘要

The prodn. of CFC-free rigid polyurethane (PU) foam with a low thermal conductivity comprises reacting (a) urethane gp-modified polyisocyanate(s) with (b) high-mol. wt. cpd(s). with at least two reactive H atoms and opt. (c) low-mol. wt. chain extenders and/or crosslinkers, in the presence of (d) blowing agents, (e) catalysts and opt. (f) additives. Component (a) consists of polyester-isocyanate semi-prepolymers with a NCO content of 31-20 wt.% obtd. by reacting excess aromatic polyisocyanate(s) (a1) with polyester-polyol(s) with a OH no., of 22-400 (a2), based on aromatic and/or aliphatic dicarboxylic acids and/or diacid derivs.