| 摘要 |
<p>The invention relates to a method for producing polyurethane rigid foams or polyisocyanurate rigid foams by reacting at least one polyisocyanate A), polyether ester polyols b) based on aromatic dicarboxylic acids which can be obtained by esterification of b1) 10 to 70 mol-% of a dicarboxylic acid composition, comprising b11) 50 to 100 mol %, based on the dicarboxylic acid composition, of one or more aromatic dicarboxylic acids or derivatives thereof, b12) 0 to 50 mol %, based on the dicarboxylic acid composition b1), of one or more aliphatic dicarboxylic acids or derivatives thereof, b2) 2 to 30 mol-% of one or more fatty acids and/or fatty acid derivatives, b3) 10 to 70 mol-% of one or more aliphatic or cycloaliphatic diols with 2 to 18 C-atoms or alkoxylates thereof, b4) 2 to 50 mol % of a polyether polyol having a functionality greater than or equal to 2, produced by alkoxylation of a polyol having a functionality greater than or equal to 2 in the presence of an amine as a catalyst, optionally additional polyester polyols C), which are different from that of components B), and at least one polyether polyol D), wherein the mass ratio of the sum of the components B) and optionally C) to component D) is at least 7. The invention also relates to the resulting hard foams and to the use thereof for the production of sandwich elements with rigid or flexible cover layers. The invention further relates to the underlying polyol components.</p> |
