Patent GB-806414-A (GB)
Title: Friction material
IPC: F16D69/02
Filed: 1956-02-16
Abstract: A friction composition for use in the manufacture of vehicle brake linings comprises a mixture of carbonized and uncarbonized friction material, the carbonized material comprising a carbonized binder and a friction imparting filler, and the uncarbonized material comprising a carbonizable binder and optionally a friction-imparting filler.  In preparing the composition the friction imparting filler, e.g. asbestos fibre, may be mixed with a binder such as a thermosetting synthetic resin and a drying oil, polychloroprene, or butadiene-acrylonitrile copolymer, or other synthetic rubber, in a solvent for the synthetic resin and rubber.  The thermosetting synthetic resin may comprise the condensation product of an aldehyde with a phenol, a melamine, cashew nut-shell liquid, aniline, cyanamide, a ketone, urea, or tannin.  To the mix may be added other fillers, e.g. talc, clay, slate, rottenstone, mica, wood flour, metal chips (e.g. brass) and powders (e.g. copper and lead), glass fibre, felt metal oxides, silica, chalk, graphite, metal nitrides, barium sulphate, and carbon black, and curing agents (e.g. hexamethylene tetramine) for the binder.  The mix is then dried and ground and a portion is spread on trays and heated sufficiently to carbonize the binder. The carbonized portion is ground and mixed with the uncarbonized portion in proportions ranging from 20 to 80 per cent by weight of the one to 80 to 20 per cent of the other.  The blend may then be moulded under pressure into a desired brake lining shape and heated to set the uncarbonized binder without carbonizing it.  The preferred binder comprises 60 to 97 parts by weight of phenol-formaldehyde and 3 to 40 parts of butadiene-acrylonitrile copolymer.  In an example the raw friction composition comprises (in parts by weight) asbestos fibre 100, barium sulphate 20, copper powder 15, brass chips 100, lead powder 15, talc 25, and 100 parts of a binder prepared from a mix of phenol-formaldehyde 170, hexamethylenetetramine 10, butadiene-acrylonitrile 20, and methyl ethyl ketone as solvent 250.  A portion of the composition is carbonized in an oven at 650 DEG  F., and 50 parts of the carbonized material are mixed with 50 parts of the uncarbonized material and the mixture is moulded under pressure at 325 DEG  F.ALSO:A friction composition for use in the manufacture of vehicle brake linings comprises a mixture of carbonized and uncarbonized friction material, the carbonized material comprises a carbonized binder and a friction imparting filler, and the uncarbonized material comprising a carbonizable binder and optionally a friction-imparting filler.  In preparing the composition the friction imparting filler, e.g. asbestos fibre may be mixed with a binder such as a thermosetting synthetic resin and a drying oil, polychloroprene, or butadiene-acrylonitrile copolymer, or other synthetic rubber, in a solvent for the synthetic resin and rubber. The thermosetting synthetic resin may comprise the condensation product of an aldehyde with a phenol, a melamine, cashew nutshell liquid, aniline, cyanamide, a ketone, urea, or tannin.  To the mix may be added other fillers e.g. talc, clay, slate, rottenstone, mica, wood flour, metal chips and powders, glass fibre, felt, metal oxides, silica, chalk, graphite, metal nitrides, and carbon black, and curing agents for the binder.  The mix is then dried and ground and a portion is spread on trays and heated sufficiently to carbonize the binder.  The carbonized portion is ground and mixed with the uncarbonized portion in proportions ranging from 20 to 80 per cent. by weight of the one to 80 to 20 per cent. of the other.  The blend may then be moulded under pressure into a desired brake lining shape and heated to set the uncarbonized binder without carbonizing it.  The preferred binder comprises 60 to 97 parts by weight of phenol-formaldehyde and 3 to 40 parts of butadiene-acrylonitrile copolymer.  In an Example the raw friction composition comprises (in parts by weight) asbestos fibre 100, barium sulphate 20, copper powder 15, brass chips 100, lead powder 15, talc 25, and 100 parts of a binder prepared from a mix of phenol-formaldehyde 170, hexamethylenetretramine 10, butadiene-acrylonitrile 20, and methyl ethyl ketone as solvent 250. A portion of the composition is carbonized in an oven at 650 DEG F., and 50 parts of the carbonized material are mixed with 50 parts of the uncarbonized material and the mixture is moulded under pressure at 325 DEG F.