Open-celled rigid polyurethane foam

摘要

Disclosed is a process for preparing an open-celled rigid polyurethane foam by reacting a polyisocyanate with a polyol in the presence of a blowing agent, usually water, and a cell opening agent. The cell opening agent comprises a combination of a polyoxyalkylene polysiloxane having a cloud point of 65 DEG C. or less, and a second substance that has a critical surface free energy of less than about 23 mJ/m2. Highly preferred as second substance is fine particulate poly(tetrafluoroethylene) polymer.