Document 8ZKXgY1BdZB7a5DmgzZGg96a

United States Patent: 4,173,681 Page 1 of8 USPTO Patent Full-Text and Image Database ( 299 of 356 ) United States Patent Durrieu , et al. 4,173,681 November 6,1979 Brake pad with integral organic backplate Abstract A disc brake pad composes an organic friction matenal layer and an organic backplate layer. Both layers are formed of pulverulent materials compacted into "green" preforms at a pressure of 80-150 bars, which are then placed m a mold where heat and pressure are applied to create the integral disc brake lad Both layers use the same resin and they may even be of identical composition Inventors. Durrieu; Jean-Pierre (Noyon, FR), Pomes; Guy (Margny-les-Compiegne, FR) Assignee Societe Abex Pagid Equipement S.A. (Clichy, FR) Appl No.. 926050 Filed July 19,1978 Foreign Application Priority Data Jul 25, 1977[FR] 77 22752 Current U.S. Class: Intern'l Class: Field of Search: 428/409,188/218XL, 188/251A; 428/327, 428/331, 428/404; 428/443, 428/702 F16D 069/02, B32B 019/02, B32B 019/06 188/218 XL,251 A,251 R 428/411,407-409,325 329,331,404,443,539,492,500 References Cited [Referenced By] 2686146 572863 3897582 3956548 Aug, 1954 Mar, 1971 Jul,1975 May, 1976 U.S. Patent Documents Gaugue Josephson Olcott Kovac et al 428/328 428/443. 428/408. 428/408 SCF-ABEX-2300 ABEX-201 05 httn //natft usnto eov/netaopi/nnh-Parser^Sertl =PTO?#S>ert?=HTTOFF#ii=/nptahtm1A:pa 10/1 S/7003 Umted States Patent: 4,173,681 4029829 |M42085 ' *4044188 4098943 4119591 1347812 May., 1977 Weaver et al. Aug., 1977 Bjerk et al. Aug, 1977 Segal Jul, 1978 Deggmger et al Oct, 1978 Aldrich Foreign Patent Documents Nov, 1963 FR Primary Examiner Ansher, Harold Attorney, Agent or Firm Greenlee; David A , Baker, Jr , Thomas S Claims Page 2 of 8 428/409. 428/325. 428/409 428/409. 188/251 What is claimed is 1. A disc brake pad comprising an organic friction material layer and an organic backplate material layer integral therewith, characterized in that the backplate layer is an unbaked preform of compacted pulverulent material, the friction layer is an unbaked preform of compacted pulverulent material, each preform containing the same resin binder, and the brake pad is formed by placing both preforms in a mold and simultaneously applying heat and pressure to join the preforms into an integral disc brake pad 2 The disc brake pad of claim 1, further characterized by the backplate preform being formed by cold compression of the pulverulent material at a pressure of 80-150 bars 3 The disc brake pad of claim 1, further characterized by the backplate preform being composed of a pulverulent mix containing 10-60% fiber, 5-40% resin, 0-30% rubber, 5-10% accelerator and vulcanization agents and 20-50% filler 4 The disc brake pad of claim 2, further characterized by the friction material preform being composed of a pulverulent mix contaimng 20-60% fiber, 0-15% resin, 0-15% rubber, 1-8% accelerator and vulcanization agents, 10-30% barium sulfate, 0-25% metal and metal alloys, 10-30% metallic by products, 0-10% organic friction modifiers, 0-6% inorganic friction modifiers, 5-20% fillers and 0-10% solvents Description This invention relates generally to disc brake pads and more particularly to such pads having organic friction material Conventional disc brake pads are composed of two very distinct materials, l e , the friction material and the metallic backplate A metal backplate has several well-defined functions which include giving a general rigidity to the friction material, transmitting the braking torque and mounting the pad m the caliper However, pads with metal backplates have certain disadvantages During brake application, the pad http //patft uspto gov/netacgi/nph-Parser7Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent: 4,173,681 Page 3 of 8 vibrates relative to the disc at high frequencies and, because of the pressure applied by the piston, causes "squeal". This results from the stress of steel-on-steel contact between the metal backplate and the piston This noise is quite objectionable Also during long braking application and under high braking pressures, the friction material can reach temperatures from 600 degree to 800 degree C. The metal backplate conducts heat well and transmits this temperature to the metal caliper piston which causes the brake fluid to boil and turn to vapor This phenomenon is very serious, because braking pressure declines dramatically Automobile disc brakes are quite exposed and are frequently wetted during ramy weather and when traversing puddles of water The metal backplates, although they are usually protected with different coatings, often become oxidized or corroded This oxidation often occurs between the friction material and the backplate and can, in some cases, cause separation or delamination of the lining Automotive friction matenals are usually composed of a high percentage (20-60%) of asbestos, which has good heat resistance and also good mechamcal strength. However, environmentalists and others are requiring a reduction or elimination in the use of asbestos in wear parts such as friction material There has been a great effort to develop friction matenals using substitutes for asbestos Some substitutes used are metallic fibers, carbon fibers, iron powder, cast iron powder But these products are very heat conductive and do not have the insulating ability of asbestos; this accentuates the phenomenon of oil boiling in the brake cylinder In order to eliminate the disadvantage of metallic backplates, orgamc backplates have been developed which compnse layers of cloth bonded by a resin, as shown in French Pat No. 1,347,812 These laminated backplates are then bonded to the friction material and have the advantage of decreasing the height of the pads smce the specific gravity of the orgamc matenal forming the backplate is only 2 These brake pads are somewhat difficult and expensive to manufacture, since the backplate must first be completely formed and then be trimmed to size before bonding to the friction matenal Accordmg to the invention, a pulverulent organic mix is compacted to create a green backplate preform, while a pulverulent organic mix is compacted to create a green friction matenal preform These mixes may be identical The organic matenal backplate preform and the friction matenal preform are arranged in a mold and are simultaneously hot pressed at temperatures and pressures suitable to flow the mixes into the mold and to bond the backplate to the friction matenal The pad obtained from this process decreases the phenomenon of oil boiling m the brake system by replacing the heat-conductive metallic backplate with an organic heat-resistant backplate. These pads are also easier and cheaper to make than those using the laminated backplates It is to be noted that the composition of the backplate is not necessarily identical with the composition of the friction matenal, although they use a common resin binder The simultaneous molding of the backplate and the friction matenal enables a complete binding between both matenals, indeed, the shearing strength of a pad with organic matenal backplate according to the invention is identical, for the same type of pad, to that of one with metallic backplate Other charactenstics and advantages of the invention will be better understood by reading the following description of a preferred embodiment, with reference to the enclosed drawings in which ^FIG 1 is a schematic sectional view of a device for compacting a backplate matenal sheet, FIG 2 is a schematic sectional view of an alternate device for pressing a backing plate preform, http //patft uspto gov/netacgi/nph-Parser`?Sectl=PT02&Sect2=HITOFF&u=7netahtml/sea 10/18/2003 United States Patent 4,173,681 Page 4 of 8 tIG. 3 is a front elevation sectional view of a press and mold, showing the backplate and friction material preforms before pressing; FIG. 4 is a sectional view taken on line 4--4 of FIG 3; and FIG 5 is a perspective view of the finished disc brake pad of this invention A preform of the organic matenal backplate is made first As shown in FIG 1, the mix of organic material in a pulverulent form is made m a mixer 11 and is directed through an openmg 12 between two rollers 13, 13a where it is laminated into a continuous strip 14 of "green" unbaked organic matenal. This stnp 14 is then punched to produce a backing plate preform 19, shown in FIG 3, ready for molding Referring now to FIG. 2, it is also possible to produce a preform of the organic matenal backplate from a pulverulent mix 15 in a mold 16 by cold compression (80-150 bars) between the mold bottom 17 and a piston 18. In a similar manner, a pulverulent organic matenal mix is cold compacted to produce a green preform 21 of friction matenal Referring now to FIG 3, the backplate preform 19 is placed in the bottom of mold 20 The friction matenal preform 21 is then placed over it The mold 20 compnses a housing 20a corresponding to the finished shape of the backplate and a housing 20b corresponding to the finished shape of the friction matenal Housing 20a is provided with cores 20c to create caliper attachment openings 23 m the |packplate The mold 20 with respective backplates and friction matenal preforms 19 and 21, is placed between the ram 22 and bed 22a of a press The preforms 19 and 21 are hot pressed at temperatures, pressures and time conditions suitable for the compositions used The friction matenal may compnse vanous mixes of organic matenals containing the following ingredients- BASIC COMPONENTS % BY WT FIBERS Asbestos 7D - 5K - 5R grade Glass fibers, carbon fibers, boron, silica, ceramic 20-60 Metallic fibers (Fe, Cu, Al, Zn, Steel) Textile fibers (natural or synthetic) RESINS Formophenolic unmodified or organic modi fied (oils, rubber) 0-15 or inorganic (boron, silane, aluminum) from straight phenol or substituted phenols (cresols, xylenols) Formol urea, melamine, other nitrogenous by-products Resins from aldehydes other than formol (furfural, benzaldehyde, croton- aldehyde) Thermostable resins other than phenolic htto //oatft usDto eov/netacei/noh-Parser9Sectl =PT02&Sect2=HTT0FF&ii=/netahtmlAea 10/1R/9001 United States Patent' 4,173,681 (polyimide, polyesterimide, polyamide- imide, polybenzimidazole, polycarbon ate, polyphenyl-sulfide, polyamide, polyester) RUBBERS Natural Mix of 30% styrene + 70% Butadiene Nitriles and acrylo-nitriles Butyl Polychloroprene 0-15 Chlorobutyl Ethylene propylene terpolymer Polyolefin Regenerated Pulverized scraps ACCELERATORS, VULCANIZATION AGENTS Sulfur Zinc oxide Magnesium oxide Mercaptobenzothiazole sulfide 1-8 Cumates Alt ax Cobalt naphthenate Hexamethymenetetramine BARIUM SULPHATE (Barites) 10-30 METALS & ALLOYS Lead Copper, zinc, aluminum, brass Antimony, tin 0-25 Bismuth Iron powder, cast iron powder Steel wool METALLIC BY-PRODUCTS Litharge, galena 10-30 Lead silicate Lead carbonate Copper sulfides Copper oxide Antimony sulfide Molybdenum sulfide Iron oxides Iron sulfide Zinc sulfide Aluminum oxide Chromium oxide Titanium oxide FRICTION MODIFIERS AGENTS Organics Resins from cashew nut oil, modified or not 0-10 Graphite Inorganics Silica Aluminum oxides Cyanites Rottenstone Chromium oxides 0-6 Page 5 of 8 http //oatft usdto eov/netaci/nDh-Parser9Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 ' United States Patent 4,173,681 Scories Glass balls Zirconium silicate MISCELLANEOUS Calcium aluminate Potassium bichromate Anti-oxidizings (agente) Carbon black Wood flour 5-20 Petroleum coke Lime Coal Chalk, kaolin, marble powder Clays Talc Lead formiate SOLVENTS Water Aromatics Aliphatics 0-10 Chlorinated Alcohols Ketones Page 6 of 8 For backplates we are using mixes of organic materials with the following composition. % BY WT FIBERS Asbestos 7D - 5K - 5R 10-60 Glass, silica, boron and ceramic fibers Graphite and carbon fibers Chopped asbestos cloth, asbestos threads (single or multiple) Metallic fibers Textile fibers (natural or synthetic) RESINS Formophenolic resins, modified or unmodi fied from straight phenol or substi tuted phenols 5-40 Formol urea, melamines, other nitrogenous resins Resins from aldehydes other than formol (furfural, benzaldehyde, croton- aldehyde) Thermostable resins other than phenolic resins (polyimides, polyesterimides, polyamide-imide, polybenzimidazole, polyphenilsulfide, polycarbonates, polyamides, polyesters) RUBBERS Natural 0-30 30% styrene + 70% butadiene Nitriles and acrylonitriles Butyl http //path uspto gov/netacgi/nph-Parser?Sectl =PT02&Sect2=HIT0FF&u=/netahtml/sea 10/18/2003 United States Patent 4,173,681 Polychloroprene Chlorobutyl Ethylene propylene terpolymer Polyolefin Regenerated Pulverized scraps ACCELERATORS, VULCANIZATION AGENTS Sulfur 5-10 Hexamethylenetetramine FILLERS Lime 20-50 Chalk Marble powder Carbon black Wood flour Magnesium stearate EXAMPLES OF MIXES FOR BACKPLATE % BY WT 12 3 4 7D Asbestos 42 40 Chopped asbestos cloth Resin 88 30% styrene + 70% butadiene 13.7 13 7 Hexamethylenetetramine Sulfur 38 3.8 Natural chalk (blanc de champagne) 24 21 Carbon black 5 Zylene solvent 85 8.5 Wood flour Magnesium stearate Magnesium oxide Graphite 16 36 7 34 1 2 4 60 30 10 Page 7 of 8 It is to be noted that m the above-indicated compositions, the resins used in the friction material and in the organic backplate must be the same to secure a complete binding between both materials Various modifications can be made by one skilled in the art to the invention described above without departing from the spirit thereof ***** Images View Cart Add to Cart Prev. 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