POLYOL BLEND FOR THE PREPARATION OF OPEN CELL RIGID POLYURETHANE FOAMS

摘要

Polyol blend comprising: (a) a polyol component having an average hydroxyl value of 150 to 850 mg KOH/g and (b) a polymer polyol comprising a polymer stably dispersed in a base polyol medium, which base polyol medium has an average primary hydroxyl content of less than 20 %. This polyol blend is suitably applied in a process for the preparation of open cell rigid polyurethane foams, wherein it is reacted with a polyisocyanate component in the presence of at least a catalyst, a foam stabilising agent and a blowing agent. The resulting open cell rigid polyurethane foam has a density of less than 50 kg/m<3> and a closed cell content of less than 10 %, preferably of less than 5 % and can suitably be applied as heat insulating material.