| abstract |
Hydrophilic rigid polyurethane foams having a density of from 15 to 50 kg/m<3> are produced by reaction of A) 4,4', 2,4'- and/or 2,2'-diphenylmethane diisocyanate, polyphenylpolymethylene polyisocyanates or a mixture of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates with B) a mixture of relatively high- and low-molecular-weight polyhydroxyl compounds containing a) from 5 to 20 parts by weight of polyoxyethylene glycol having a hydroxyl number of from 100 to 500, b) from 10 to 40 parts by weight of at least one tetrafunctional oxypropylated aliphatic diamine having a hydroxyl number of from 500 to 800, c) from 10 to 30 parts by weight of diethylene glycol, d) from 0 to 10 parts by weight of at least one graft and/or filler polyether-polyol dispersion, e) from 0 to 40 parts by weight of at least one difunctional to octafunctional polyoxyalkylene ether polyol having an OH number of from 300 to 500 and f) from 0 to 30 parts by weight of trimethylolpropane, and C) water, in the presence of D) catalysts and optionally E) physical blowing agents, F) assistants and/or additives, where components A, B and C are reacted in such amounts that the NCO index is from 30 to 90. The products are used as substrates for plant cultivation, as support materials for biomasses, catalysts or ion exchangers, as support foams for cut flowers or as cleaning agents. |