| 摘要 |
The invention relates to a method for producing polyurethane hard foams or polyisocyanurate hard foams by reacting at least one polyisocyanate A), polyether ester polyols B) based on aromatic dicarboxylic acids obtainable by esterification of b1) 10 to 70 mol% of a dicarboxylic acid composition containing b11) 50 to 100 mol%, in relation to the dicarboxylic acid composition, of one or a more aromatic dicarboxylic acids or derivatives thereof, b12) 0 to 50 mol%, in relation to the dicarboxylic acid composition b1), of one or a 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 having 2 to 18 C atoms or alkoxylates of the same, 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 2, where necessary further polyester polyols C), which differ from those of component B), and at least one polyether polyol D), wherein the mass ratio of the sum of components B) and, where applicable, C) to component D) is at least 7. The invention also relates to the hard foams obtainable in said manner and to the use thereof for producing sandwich elements having rigid or flexible covering layers. The invention further relates to the basic polyol components. |
