| abstract |
The present invention relates to a process for producing rigid polyurethane foams or rigid polyisocyanurate foams by converting at least one polyisocyanate and a polyol composition (PZ), wherein the polyol composition (PZ) comprising at least one compound having at least two hydrogen atoms reactive with isocyanate groups and at least one dicarboxylic acid diester selected from the group consisting of dicarboxylic acids having 2-18 carbon atoms and having 3-18 Compound (I) of a tricarboxylic acid triester of a tricarboxylic acid having three carbon atoms. At least one blowing agent is used in the conversion process. The invention also relates to rigid polyurethane foams or rigid polyisocyanurate foams obtained or obtainable by this method, and to polyol compositions (PZ) comprising at least one Compounds having at least two hydrogen atoms reactive towards isocyanate groups and at least one diester of dicarboxylic acids selected from the group consisting of dicarboxylic acids having 2-18 carbon atoms and tricarboxylic acids having 3-18 carbon atoms Compound (I) of the tricarboxylic acid triester. The invention also relates to the use of such a polyol composition (PZ) in the production of rigid polyurethane foams or rigid polyisocyanurate foams, and to rigid polyurethane foams or rigid polyisocyanurate foams of the invention Use of ester foams as thermal insulation materials or for the manufacture of thermal insulation materials, preferably thermal insulation panels, sandwich elements, hot water tanks, boilers, cooling plants, thermal insulation foams, cooling units or freezers. |