Process for the preparation of substantially closed-cell rigid foams containing urethane, urea, biuret, and isocyanurate groups and a method of use thereof

摘要

The present invention relates to a process for the preparation of substantially closed-cell rigid foams containing urethane, urea, biuret, and isocyanurate groups comprising reacting, at an index of greater than 110, organic polyisocyanates with relatively high molecular weight polyots consisting of mixtures of (i) polyesters containing at least two hydroxyl groups and having an OH value of greater than 150 and/or polyethers containing at least two hydroxyl groups and having an OH value of greater than 200, and (ii) polyoxyalkylene polyethers containing ethylene oxide residues and least two hydroxyl groups and having an OH value of less than 100, in the presence of isocyanate trimerization catalysts and water as blowing agent. The foams of the invention can optionally be prepared optionally, in the further presence chain-extending and/or crosslinking agents and auxiliaries. and/or additives. The present invention also relates to a method using the foams of the invention as insulating materials and/or for reinforcing mechanical structural components.