Silicone surfactants for rigid polyurethane foam made with third generation blowing agents

摘要

A method for making a rigid polyurethane foam by reacting a polyisocyanate and a polyol in the presence of a urethane catalyst, a blowing agent and a silicone surfactant characterized by employing as a blowing agent a C1-C4 HFC or HCFC, preferably HFC-245fa, and as the silicone surfactant a polyether-polysiloxane copolymer having a total surfactant molecular weight of 12,000 to 100,000 g/mole, a wt% siloxane in the surfactant of 10 to 40 wt%, a molecular weight of the polyether portion of 1200 to 6,000 g/mole, and a wt% of ethylene oxide in the polyether portion of 30 - 100 wt%.