| abstract |
This invention provides a process for producing rigid polyurethane foams by reacting A) a polyol component with B) a polyisocyanate component in the presence of C) water, D) at least one catalyst, and, optionally, E) at least one blowing agent. This process specifically requires A) a polyol component which comprises: 1) a polyol containing at least two isocyanate-reactive hydrogen atoms and comprising: a) a mixture of i) an addition product having a OH number of at least 500 of diamines or polyamines containing primary and/or secondary amino groups with alkylene oxides, and ii) castor oil, and/or b) one or more reaction products obtained by reacting i) an addition product having a OH number of at least 500 of diamines or polyamines containing primary and/or secondary amino groups with alkylene oxides, and ii) castor oil; and 2) at least one compound containing at least two isocyanate-reactive hydrogen atoms. Suitable polyisocyanates B) for the present invention are those containing an NCO group content of from 20 to 48% by weight. |