| 摘要 |
In a process for producing rigid polyurethane foams having improved heat distortion resistance and reduced thermal conductivity by reacting a) polyisocyanates with b) compounds containing hydrogen atoms reactive toward isocyanates, in the presence of c) water, and, if desired, d) physically acting blowing agents and e) catalyst and known auxiliaries and/or additives, the compounds b) containing hydrogen atoms reactive toward isocyanates are a polyol mixture comprising b1) a polyol which can be prepared by addition of ethylene oxide and/or propylene oxide onto a hexitol or a hexitol mixture, with the total hexitol content of the polyol mixture being from 15 to 30 % by weight, based on the polyol mixture, and b2) a polyol which can be prepared by addition of ethylene oxide and/or propylene oxide onto one or more aromatic amines, with the total amine content of the polyol mixture being from 1 to 10 % by weight, based on the polyol mixture, and the amount of the polyol mixture in the component b) is from 60 to 100 parts by mass per 100 parts by mass of the component b).
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