Abstract: A primary object of the invention is to provide a method of producing rigid polyurethane foams using 1,1-dichloro-1-fluoroethane (HCFC-141b) as the blowing agent while substantially avoiding the formation of decomposition products from HCFC-141b. The above object can be achieved by a method of producing rigid polyurethane foams which comprises reacting a polyol with an organic polyisocyanate for foaming in the presence of HCFC-141b and a stabilizer therefor and in the presence of an organic metal catalyst and/or an imidazole compound catalyst and by the thus-produced rigid polyurethane foams.

Abstract: A method of producing an open cell rigid polyurethane foam which comprises reacting a polymethylene polyphenylisocyanate prepolymer with a polyol at an NCO/OH equivalent ratio of 1.3 to 3.0 by use of a blowing agent substantially comprising water in the presence of a catalyst, a foam stabilizer and a cell opening agent.

Abstract: A method of producing an open cell rigid polyurethane foam which comprises reacting a polyol with a polymethylene polyphenyl polyisocyanate prepolymer with a monool exemplified by diethylene glycol monomethyl ether by use of a substitute such as 1,1-dichloro-1-fluoroethane or methylene chloride as a volatile blowing agent, or a mixture of the volatile blowing agent with water, for trichlorofluoromethane as a blowing agent in the presence of a catalyst, a foam stabilizer and a cell opening agent. The resultant open cell rigid polyurethane foam has a cell size of about 200-250 microns, and is suitable for use, for example, as a core material in a vacuum heat insulating material. The foam may be enclosed in a container under a vacuum of 0.1-0.01 mmHg readily attainable to provide a vacuum heat insulating material of a high heat insulating performance.

Abstract: A method for producing a fire-resistant, thermally insulating board, which comprises applying liquid hydrated sodium silicate (B) onto the inner surface of a facing material or sheet (A), spreading powdery hydrated sodium silicate (C) over the said applied surface, laying the said spread surface on(1) a facing material or sheet (D),(2) a facing material or sheet (D) applied in advance with liquid hydrated sodium silicate (B) or(3) a facing material or sheet having powdery hydrated sodium silicate (C) spread further over the applied surface of (2),implementing the heating and pressing procedure for gluing the assembly, and laminating the resulting fire-resistant board (E) with rigid isocyanurate foam (F).The fire-resistant, thermally insulating board shows reduced fusing and combustion of the rigid isocyanurate foam (F) even when exposed to flame and posseses superior mechanical properties.