Patent GB-478703-A (GB)
Title: Improvements in or relating to friction linings and elements
IPC: F16D69/02
Filed: 1936-07-20
Abstract: Brake linings and clutch facings comprise a filler, and a binder consisting wholly or partially of a vinyl-phenol-methylene resin obtained from a methylene-yielding compound, such as aldehydes (e.g. formaldehyde) or ketones, and a vinyl-phenol condensate obtained by condensing a vinyl compound with a phenol so that the product has a phenol group and an unsaturated group attached to the aromatic nucleus.  Vinyl compounds specified are vinyl acetate, vinyl chloride, styrene, amylene, divinyl, phenyl divinyl, isoprene, and divinyl acetylene: phenols specified are phenol and alkyl- or aryl-substituted phenols such as cresol, xylenol, tert.-butyl phenol, tert.-amyl phenol, and phenyl-phenol. The vinyl-phenol condensate may be polymerized or partly polymerized before, during, or after condensation with the methylene-yielding compound.  Suitable fillers are asbestos in woven or unwoven form, coke, crushed coal, metal particles.  The binder may also contain modifiers such as pitch, bitumen, tars, asphaltite, pyrogenous or other asphalts; drying, non-drying or semi-drying oils, e.g. castor oil, tung oil, linseed oil; polymerized drying oils, e.g. linseed oil; natural or synthetic resins, e.g. rosin, copal, coumarone; rubber, rubber latex, polymerized halogenated divinyl compounds; phthalates, abietates, e.g. ethyl abietate, benzoates, e.g. ethylene glycol dibenzoate, and glycols, e.g. diethylene glycol.  For the incorporation of the fillers and modifiers, the reaction between the vinyl-phenol and the methylene-yielding agent may be suspended in the liquid stage (e.g. by cooling) or be carried further and the product dissolved, e.g. in a drying oil; fibrous filler may be formed by weaving or pulping, given the desired shape, and impregnated with binder; the binder may be mixed with or coated on the filler and the composition shaped, e.g. the binder may be added to an aqueous pulp of the filler, the mixture formed into sheets, which are then folded or superimposed to form a thick sheet which may be shaped; or the binder may be incorporated with an aqueous pulp of the filler and moulded, e.g. by extrusion.  The lining or facing is heated to complete the condensation.  In examples: (1) m- and p-cresol are refluxed with vinyl acetate, if desired in the presence of oxalic acid, and then condensed with paraformaldehyde; (2) phenol and styrene in ethyl benzene solution are refluxed in the presence of oxalic acid and then condensed with paraformaldehyde; (3) woven asbestos tape (or other fabric as tapes, webs, or strips with or without wire reinforcement) is impregnated with a mixture of raw tung oil, raw linseed oil, asphalt, the resin of example 1, wood tar, and driers dissolved in coal-tar solvents or gasoline, freed from solvents and heated; (4) resin of example 2 is dissolved and mixed with short fibre asbestos, rolled to a sheet, and hot moulded.  The Specification as open to inspection under Sect. 91 refers to the use of "alkene-phenol" condensates.  By "alkene" is meant an unsaturated hydrocarbon or derivative thereof, e.g. linseed oil, tung oil, perilla oil, soya-bean oil, "siticica oil," the acids therefrom or their polyhydric alcohol esters; ethylenic compounds such as organic and inorganic esters of ethylenic alcohols, aryl and alkyl substituted ethylenes; "alkenynes, alkapolyenes, alkanynes and their substitution derivatives." Examples are included in which (1) commercial cresol is reacted with tung oil in the presence of boric acid, then condensed with hexamethylene-tetramine; (2) commercial phenol and tung oil are reacted in the presence of oxalic acid, then condensed with paraformaldehyde with the addition of zinc oxide; (3) commercial xylenol was reacted with linseed oil in the presence of zinc oxide then condensed with hexamethylenetetramine.  This subject-matter does not appear in the Specification as accepted.