Preparation of urethane and isocyanurate foams in the presence of a low boiling point blowing agents

摘要

This invention relates to a process for preparing a rigid, closed-celled polyisocyanate-based foam in the presence of water and a blowing agent. The blowing agent comprises one or more organic compounds, particularly halocarbons, having a boiling point of from 222K to 272K at atmospheric pressure, and is substantially free of organic compounds having a boiling point of 273K or greater. Preferred halocarbons are chlorofluoroethanes, especially chlorodifluoroethane (R-142b) and fluoroethanes.