Rigid polyurethane foam with improved elasticity and wear resistance - by dissolving a high polymer, pref. polyvinyl butyral, in the poly:ol-di:isocyanate mixt. before foaming

摘要

A process is claimed for the prodn. of polyurethane (PU)-based rigid foam with improved elasticity and abrasion resistance (I), by dissolving a high polymer (II) in the mixt. of polyol and di-isocyanate before foaming. (II) is polyvinyl butyral (PVB), in amts. of 2-30 (pref. 5-15) wt.%. USE/ADVANTAGE - The process enables the prodn. of rigid PU foam with improved elasticity, impact resistance and abrasion resistance. This foam can be stepped on and driven over with heavy vehicles, and also fixed directly with nails and screws, and is therefore suitable for insulating surfaces which are subjected to loads (roofs, tanks, piping, refrigerators, etc.). In an example, 8.7 wt.% PVB was dissolved in a mixt. of 24.65 wt.% polyol contg. 11.5% OH and 24.65 wt.% polyol contg. 3.4% OH, then 42.00 wt.% di-isocyanate (31.5% NCO) was added with stirring, followed by 0.2-0.6 wt.% water as blowing agent. The prod. had density, 160-200 kg/m3 (depending on the amt. of water added); elongation 17-24%; flexural load (20mm deflection) 0.111-0.112 MPa. Corresp. values without PVB were: 182-201 kg/m3, 15.2-15.8%, 0.191-0.202 MPa (some samples fractured before reaching 20mm deflection).