Abstract: A method of manufacturing polyurethane foams comprising the steps of mixing a polyol and an organic isocyanate without causing them to substantially react with each other thereby to obtain a nonreacted mixture, mixing the nonreacted mixture with a foaming agent, a catalyst, a foam stabilizer and other necessary additives such as a pigment, a fire retardant and a filler, and injecting the resultant mixture to a mold to cause the resultant mixture to foam and crosslink. The polyol and the organic isocyanate may be preliminarily mixed with a gas such as an inert gas or air. The nonreacted mixture containing the polyol and organic isocyanate may be subjected to aging at a temperature of -10.degree. to 25.degree. C. for 12 to 27 hours.

Abstract: A method of producing polyurethane foam slab by allowing a urethane foam stock solution in a tank to expand in a reduced pressure. The flatness of the top of the polyurethane foam is secured by providing a lifting jig or a plate within the tank, or by rotating the tank. An apparatus for carrying out the method is also provided.

Abstract: A method of manufacturing a modified polyhydroxy compound, which is characterized in that a polyhydroxy compound is heated for 30 minutes or more at a temperature ranging from 150.degree. to 250.degree. C. under stirring and in the presence of tin, tin compounds such as tin halogenide, tin hydroxide and tin oxide. The polyhydroxy compound modified by this method is effective in improving the foamability and mechanical strength of urethane foam, when it is used as a raw material in the manufacture of urethane foam.

Abstract: An apparatus for continuously manufacturing polyurethane foam slabs in a batch, which comprises a cylindrical tank for developing polyurethane foam, having an inlet at the side wall thereof for introducing therein polyurethane feed solution; a stirring tank for forming polyurethane foam feed solution, which is mounted on a carriage movably placed in proximity to the cylindrical tank; stirring blades mounted within the stirring tank; a discharge pipe extending from a lower side of the stirring tank to discharge the feed solution through the inlet into the cylindrical tank; pipes for introducing raw materials into the stirring tank; and a pipe for introducing a washing solvent for removing the raw materials. The cylindrical tank is interchangeably connected with the stirring tank through the discharge pipe.

Abstract: An asphalt foam having open cells wherein asphalt mixed with an alkali metal silicate is fixed to the wall of the open cells. The asphalt foam is useful for a joint filler, a vehicle floor material, etc. A method of producing the asphalt foam, which comprises the steps of impregnating an open cell foam sheet with an aqueous mixture consisting of asphalt emulsion and an aqueous solution of an alkali metal silicate, and drying the impregnated foam sheet.