| abstract |
Thermoplastic PU foams (I) are claimed, based on foamed, glass fibre-reinforced thermoplastic polyurethanes (II). Also claimed is a process for the prodn. of (I), by addn. of a blowing agent (III) to granules of (II). More specifically amt. of glass fibre (GF) is 5-50 (pref. 10-30) wt.% w.r.t. thermoplastic PU (TPU); for prodn. of (I) by injection moulding, (III) is azodicarbonamide, bicarbonate or 5-phenyl-tetrazole; the GF has length/thickness ratio (L/T) above 1, pref. (4:1)-(150:1), and the TPU is. based on long-chain cpd(s). (A) with at least 1.8 Zerewitinoff-reactive gps. and mol. wt. 400-10,000, chain extender(s) (B) with about 2 reactive gps. and mol. wt. 18-350 and diisocyanate(s) (C). USE/ADVANTAGE - (I) are useful as structural foam materials, esp. produced by injection moulding. They have relatively high-elastic modulus and low density, good surface appearance, a foam structure even at low wall thickness, and good noise protection -properties. The claims include thermoplastic mouldings produced from (I) by injection -moulding, esp. with wall thickness below 10 mm and density reduced by 5-50 wt.% due to foaming. (A) are, e.g. polyesters, polyethers, polyacetals, polycarbonates, etc. with about 2 reactive H, (B) is, e.g. ethylene glycol, butanediol, triethylene glycol, hexamethylene-diamine, IPDA, etc., (C) is, e.g. MDI, TDI, HMDI, IPDI, etc.; pref., (I) have Shore hardness 65A-75D. |