Patent GB-448102-A (GB)
Title: Improvements in and relating to grinding and polishing bodies, and methods of manufacturing the same
IPC: C08L61/10
Filed: 1934-10-22
Abstract: Porous grinding bodies are produced from a mix comprising abrasive grains, a heat hardenable artificial resin of a nature such that it becomes soft or viscous but not thinly liquid during the subsequent heat treatment of the mix, and a substance which evolves gas on being heated.  The mix is heated in a closed mould, the upper part of which is provided with fine perforations which allow gas but not the mix to escape, to a temperature at which gas is evolved and then further heated until the mass is solidified. p  If the artificial resin is one which evolves gas on being heated the addition of a separate gas evolving substance may be omitted. Resins specified are phenol resins, resins of a phathalic acid basis and urea formaldehyde resins; they may be brought into a suitable condition for carrying out the process by heat treatment, with or without abrasive grains and if desired in the presence of a catalyst, e.g. phenol formaldehyde resins may be heated for some hours at about 150 DEG C., or by merely storing the resin for some time at the ordinary temperature.  Abrasive materials specified are corundum, silicon carbide, emery and powdered glass.  Gas generating substances specified are carbonates or bicarbonates of ammonia, the alkali metals or amines, and urea peroxide with or without manganese peroxide as a catalyst.  According to the Specification as open to inspection under Sect. 91 the mix of abrasive grains, artificial resin and gas generating substance may be heated in open moulds. This subject-matter does not appear in the Specification as accepted.ALSO:Porous grinding bodies are produced from a mix comprising abrasive grains, a heat hardenable artificial resin of a nature such that it becomes soft or viscous but not thinly liquid during the subsequent heat treatment of the mix, and a substance which evolves gas on being heated.  The mix is heated in a closed mould, the upper part of which is provided with fine perforations which allow gas but not the mix to escape, to a temperature at which gas is evolved and then further heated until the mass is solidified. If the artificial resin is one which evolves gas on being heated the addition of a separate gas evolving substance may be omitted.  Resins specified are phenol resins, resins of a phthalic acid basis and urea formaldehyde resins; they may be brought into a suitable condition for carrying out the process by heat treatment, with or without abrasive grains and if desired in the presence of a catalyst, e.g. phenol formaldehyde resins may be heated for some hours at about 150 DEG  C., or by merely storing the resin for some time at the ordinary temperature.  Abrasive materials specified are corundum, silicon carbide, emery and powdered glass.  Gas generating substances specified are carbonates or bicarbonates of ammonia, the alkali metals or amines, and urea peroxide with or without manganese peroxide as a catalyst.  According to the Specification as open to inspection under Sect. 91 the mix of abrasive grains, artificial resin and gas generating substance may be heated in open moulds. This subject-matter does not appear in the Specification as accepted.