US Patent 7285577 Method for producing rigid polyurethane foam

A method to produce a rigid polyurethane foam includes emulsifying a nucleating agent by mixing the nucleating agent with a polyol and a foam stabilizer, preparing a polyol mixture by mixing water, a catalyst, and a blowing agent at one of: before the emulsifying, during the emulsifying and after the emulsifying, and reacting the polyol mixture with a polyisocyanate.