Patent GB-712074-A (GB)
Title: Improvements in or relating to a friction material composition and a method of producing the same
Inventor: NOVAK IZADOR JACOB
IPC: F16D69/02
Filed: 1952-07-09
Abstract: A friction material composition comprises 50-75 per cent. of short-fibre asbestos, 15-30 per cent. binder solids which include peptized synthetic rubber, and up to 35 per cent. of friction material fillers together with solvent for the binder in the proportion of from 5-15 per cent. of the composition solids. Specified rubbers are butadiene-acrylonitrile, butadiene-styrene and poly-2-chloro-1:3 butadiene, while specified fillers are hardwood pitch, talc, cashew nut shell liquid resins, graphite, brass chips, litharge, mica and rosin, and specified solvents are mineral spirits, gasoline and toluene.  The rubber may be peptized by treating with phenyl hydrazine, xylyl mercaptan and copper oleate or by air oxidation accompanied by heat.  Bodied linseed or china wood oil may also be present while the rubber may be vulcanized.ALSO:A friction material composition comprises from 50 to 75 per cent, by weight of short-fibre asbestos, from 15 per cent. to 30 per cent. by weight of binder solids including peptized natural rubber providing the composition with from 3 to 15 per cent. by weight of rubber, binder vulcanizing agent, 0 to 35 per cent. by weight of friction material fillers such as hardwood pitch, talc, cardolite powder (cashew nut shell liquid resin), graphite, brass, chips, litharge, mica and rosin and solvent for the binder in the proportion of from 5 to 15 per cent. by weight of the composition solids.  The binder solids, which may include other ingredients such as bodied or unbodied drying oils, e.g. bodied China wood oil and linseed oil, may be vulcanized or hardened by sulphur, accelerators, or other vulcanizing or hardening ingredients.  The peptized rubber material and solvent may be pre-mixed to form a cement, and the oil, fillers and the like are mixed therewith to a heavy slurry and which is then mixed with the asbestos fibres. Conveniently the peptized rubber material may be introduced in solid pieces with the solvent and filler materials into a dough mixer such as a Werner-Pfleiderer mixer and after the rubber has been thoroughly dissolved and mixed to a smooth slurry with the fillers, the asbestos fibres are mixed therewith until even distribution of the binder has been obtained, when the resulting mix is aged at room temperature for 1 or 2 days and then pulverized in a hammer mill to produce a mass of loose relatively uniform particles which flows by gravity, is highly compressible and the particles have strong tack on being pressed together.  In a preferred method this granular material is agitated in a mixer and flowed therefrom by gravity in controlled amounts to and between the nip of rotating rolls one of which is provided with a pair of flanges or confining walls, the other being spaced from the latter roll by projecting within the flanges of the latter so that the granular mix is compacted between the rolls and issues as strip material of a self-sustaining nature so that it can be rolled up and handled prior to curing without reinforcement or support.