Patent GB-634888-A (GB)
Title: Grinding wheels and other abrasive bodies and method of making the same
IPC: C08L61/06
Filed: 1947-09-30
Abstract: An abrasive article, e.g. a grinding or cutting wheel, particularly for use on stone, comprises abrading grains, e.g. fused alumina, corundum or silicon carbide, bonded by means of a composition comprising 50-90 per cent volume of shellac and the remainder of phenol-formaldehyde or polyhydric alcohol-polybasic acid resin or mixtures thereof, containing 5-50 per cent by weight of a nitroparaffin having 2-4 carbon atoms.  The nitroparaffin may be hydroxylated or halogenated (see Group IV (b)); suitable substances are 2-nitrobutanol, 1-nitropropane, 2-nitropropane and nitro-ethane. The abrasive grain is first mixed with the artificial resin and nitroparaffin, and powdered shellac is subsequently added, together, if required, with a filler such as cryolite.  A small amount of chinawood or tung oil may be added to retain dust.  The mixture is then cold pressed at a pressure not exceeding 2000 lbs. per square inch and is finally cured in an oven at 160 DEG  C. for twenty-four hours.ALSO:A nitro-paraffin having 2-4 carbon atoms, and which may be hydroxylated or halogenated, is added to a bond for an abrasive article comprising shellac and a phenol-formaldehyde and/or polybasic acid-polyhydric alcohol resin.  Suitable substances are 2-nitro-butanol, 1-nitro-propane, 2-nitro-propane, and nitroethane. The nitro-paraffins may be prepared from the appropriate alcohol, which is halogenated, if desired, and is then vaporized and passed with nitrogen dioxide through a zone heated to about 600 DEG  C. Alternatively, the paraffin or mixture of paraffins is passed through a hot zone with nitrogen dioxide.  If halogenated or hydroxylated products are desired, the resultant is halogenated and then hydroxylated by treatment with an alkali, thus leaving a double bond where the halogen was removed, and finally adding water containing sulphuric acid which hydroxylates the compound at the double bond. If fluorinated compounds are desired, a fluorinated paraffin, made by passing the paraffin through a fluorine generator, is used.  Other halogenated compounds are prepared by bubbling chlorine through, or adding bromine or iodine to, the nitro-paraffin in the presence of a catalyst such as phosphorus pentachloride.ALSO:An abrasive article, e.g. a grinding or cutting wheel particularly for use on stone, comprises abrading grains, e.g. fused alumina, corundum, or silicon carbide, bonded by means of a composition comprising 50-90 per cent volume of shellac and the remainder of phenol-formaldehyde or polyhydric alcohol-polybasic acid resin or mixtures thereof, containing 5-50 per cent by weight of a nitro-paraffin having 2-4 carbon atoms.  The nitro-paraffin may be hydroxylated or halogenated, (see Group IV (b)); suitable substances are 2-nitro-butanol, 1-nitro-propane, 2-nitro-propane, and nitro-ethane.  The abrasive grain is first mixed with the artificial resin and nitro-paraffin, and powdered shellac is subsequently added, together if required with a filler such as cryolite.  A small amount of chinawood or tung oil may be added to retain dust.  The mixture is then cold pressed at a pressure not exceeding 2,000 lb. per square inch and is finally cured in an oven at 160 DEG C. for twenty-four hours.