Process for preparing cement product (US Patent 4,152,168, 1979)

Naomichi Yano and Kuniaki Sato received US Patent No. 4,152,168 on May 1, 1979, filed November 3, 1977. It was assigned to Kubota Corp.

The patent's abstract:

A process comprising the steps of adding an inorganic foamed aggregate, an inorganic solid aggregate and a reinforcing fiber to cement to prepare a cement mixture, kneading the cement mixture with addition of 3 to 15% by weight of water based on the mixture to obtain a relatively hard kneaded mixture, press-molding the kneaded mixture at pressure of 200 to 600 kg/cm 2 , adding water to the molded piece to adjust the water content thereof, preheating the molded piece at a temperature of 40° to 70° C. before curing, spraying to the surface of the heated molded piece an aqueous dispersion prepared from resin and cement-type coloring material and containing inorganic particles 0.1 to 1.5 mm in size, drying the coated piece, applying a colored resin composition to the coating, and curing the resulting piece in an autoclave with pressurized steam, whereby a colored roofing panel or like cement product can be prepared.

Where it was listed

• Asbestos, November 1979, in its patents department (the year's issues)