| 摘要 |
<p>Prepn. of polyisocyanurate rigid foams by reaction of (A) a polymethylene polyphenyl polyisocyanate contg. >=80 wt. % diisocyanato diphenyl methane with (B) a polyol mixt of (a) a polyether with OH value 28-112 and >=20 (30-50) wt. % of the alkylene oxide content consisting of ethylene oxide gps. and (b) a glycol of mol. wt. 62-200, in presence of usual isocyanate trimerisation catalyst, blowing agent and other usual additives. Amt. of (a) is 0.015-0.04 OH equivs. and of (b) 0.2-0.4 OH equivs., per NCO equiv. Used to make internal cover and impact-absorbing components of vehicles, tractors, cranes, etc., sound-absorbing roof and wall elements in building and for enclosing machines; thermal insulation for vessels, pipes, houses, etc; protective packaging of fragile equipment; furniture components, e.g. seat sheels, table tops, etc; orthopaedic aids, e.t. splints, protective pads; shoe components, e.g. inner soles. The foam is non-brittle and can be hot-formed at 150-210 degrees C, or embossed in sharp contours, undergoing large thickness reductions without damage.</p> |
