Document nmdEx62pO70oRKkJEpg7o0vYX

' United States Patent 4,217,255 Page 1 of 9 USPTO Patent Full-Text and Image Database (286 of 356 ) United States Patent Griffith Composition railroad friction material with synthetic fiber content 4,217,255 August 12, 1980 Abstract Composition railroad fnction materials having low wear rates are characterized by the use of synthetic fiber and by the absence of lead and asbestos These friction matenals are particularly suitable for use in railroad brake shoes and contain, by approximate weight, 0 5-11% non-asbestos fiber, of which at least 0 5% is synthetic fiber, 66-81% filler and 14-21% organic binder Inventors Griffith; Arvon M. (Valley Cottage, NY) Assignee Abex Corporation (New York, NY) Appl No 030411 Filed April 16,1979 Current U.S. Class: Intern'1 Class: Field of Search: 3684062 3907729 3922241 3959194 IB967037 523/156, 188/251 A, 188/251R, 523/512, 523/514, 523/515; 523/516, 523/526, 523/527, 524/32, 524/63, 524/423; 524/566, 524/575 C08L 001/02, F16D 069/00 260/17 2,17 4 CL,38,42 18 References Cited [Referenced By] Aug, 1972 Sep , 1975 Nov, 1975 May, 1976 Jun, 1976 U.S. Patent Documents Johnson Burkey et al Barker et al Adelmann Marzocchi et al 188/251 260/17 260/17 188/251 428/392 Other References - SCF-ABEX-2385 ABEX-203 10 http //path uspto gov/netacgi/nph-Parser9Sectl=PT02&Sect2=HTTOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Page 2 of 9 vol 83 61074n, Less Abrasive Composition Railroad Brake Shoe Matenal, Adelmann C A vol 85 165565f, Glass-fiber-based friction matenal, Sasahara CA vol 79 8003 le, Fiber Strengthened Friction Matenal, Augustin Primary Examiner Woodberry, Edward M Attorney, Agent or Firm Greenlee, David A , Baker, Jr , Thomas S Parent Case Text This is a continuation of application Ser No 815,637, filed July 14, 1977, now abandoned Claims I claim 1. An asbestos-free and lead-free composition friction matenal, compnsing, by weight, 0 5-11% fiber, of which at least 0 5% is synthetic fiber, 66-81% filler and 14-21% organic binder The friction matenal of claim 1, wherein the fiber content includes at least 1% glass fiber 3 An asbestos-free and lead-free composition friction matenal, compnsmg, by weight, 1 5-10% fiber, of which at least 0 5% is synthetic fiber and at least 0 4% is cellulose fiber, 66-80% filler and 14-21% organic binder 4 The friction matenal of claim 3, wherein the fiber content includes at least 1 5% glass fiber 5 An asbestos-free and lead-free composition friction material, compnsmg, by weight, 5-10% fiber, of which at least 2 5% is synthetic fiber and at least 2 5% is cellulose fiber, 72-79% filler and 14-19% organic binder 6 The friction matenal of claim 5, wherein the synthetic fiber is glass fiber 7 An asbestos-free and lead-free composition friction material, compnsmg, by weight, 2-5% fiber, of which at least 1% is synthetic fiber and at least 0 5% is cellulose fiber, 72-82% filler and 14-21% organic binder 8 The friction matenal of claim 7, wherein the synthetic fiber is glass fiber 9 An asbestos-free and lead-free composition friction material, compnsmg, by weight, 0 5-7% synthetic fiber, 72-81% filler and 15-21% organic binder 0 The friction matenal of claim 9, wherein the synthetic fiber is glass fiber 11 An asbestos-free and lead-free composition friction material, compnsing, by weight, 0 5-2% synthetic fiber, 74-82% filler and 15-22% organic binder http //path uspto gov/netacgi/nph-Parser?Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Page 3 of 9 r The friction material of claim 11, wherein the synthetic fiber is polyester fiber 13 An asbestos-free and lead-free composition friction material, comprising, by weight, 1 4-3 5% synthetic fiber, 74-82% filler and 16-21% organic binder 14 The friction matenal of claim 13, wherein the synthetic fiber is glass fiber 15 The asbestos-free and lead-free composition friction material, comprising, by weight, 2 7-3 5% synthetic fiber, 74-82% filler and 16-19% organic binder 16 The friction matenal of claim 15, wherein the synthetic fiber is glass fiber Description This invention relates generally to composition type railroad friction matenals and, more particularly, to such matenals which feature the use of synthetic fibers and the absence of asbestos and lead BACKGROUND OF THE INVENTION Most of the composition type railroad friction matenals m use today include asbestos and lead An example of this type of matenal is shown in U S Pat No 3,168,487--Spokes et al Some Kivironmentalists have warned of possible problems caused by the use of lead in friction matenals As a suit, demand has developed for a lead-free friction matenal Examples of some composition fnction matenals which exclude lead are U S Pat Nos 3,492,262--Gnffith and 3,959,194--Adelmann The former patent discloses a composition which has no lead and includes up to 16 5% by weight asbestos fiber, while the latter patent discloses some compositions which delete lead and have up to 11 1 % by weight asbestos fiber More recently, certain environmentalists have pointed out that possible problems may be caused by the use of asbestos fiber in fnction matenals Thus, it may be desirable to eliminate asbestos as well as lead from composition friction materials US Pat No 3,959,194 has some examples which utilize cellulosic fiber in a range of 3 5-8 0% by weight as a substitute for asbestos, although the patent is not concerned with eliminating asbestos in friction matenals Asbestos has traditionally been used in friction matenals because of its high heat resistance and strength and its low cost. A direct substitution of other types of fiber for asbestos is expensive, since other fibers cost much more than asbestos, and difficult, since no known fiber combines all of the desirable qualities of asbestos noted above It is known to use high-content carbonized or graphitized fibers in aircraft fnction matenals, as shown in U S Pat No 3,552,533--Nitz The use of glass fiber in friction materials is disclosed m several patents U S Pat No 3,743,069--Barnett relates a clutch facing consisting almost entirely of bundles of continuous glass filaments US Pat No 3,627,606--Bentz teaches a glassfilament-reinforced fabnc clutch facing impregnated with a cement containing lead (litharge) U S Pat No 3,713,934--Morton discloses a clutch facing composed of glass and asbestos None of these friction matenals would be suitable for railroad brake shoe use, since they are either too expensive and/or Kontain lead or asbestos It is, therefore, an object of this invention to provide lead-free, asbestos-free, high coefficient of friction, composition friction matenals which feature a low fiber content including synthetic fiber and low wear http //patft uspto gov/netacgi/nph-Parser?Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Page 4 of 9 rates. UMMARY OF THE INVENTION I have discovered that railroad brake shoes that meet AAR (Association of American Railroads) standards for brake shoes can be made from compositions having a low, non-asbestos fiber content which includes synthetic fiber The friction matenals according to this invention compnse, by weight, 0 5-11 0% non-asbestos fiber, including at least 0 5% synthetic fiber, 66-81% filler and 14-21% organic binder A preferred embodiment of this composition friction material for railroad car use contains 2 7 3 5% synthetic fiber, 74-82% filler and 16-19% organic binder DETAILED DESCRIPTION OF THE INVENTION The criterion for suitability of a composition friction material for railroad car brake shoe use is the ability of the friction material to pass the standards set forth in the A A R Specification M-926-72, Feb 13, 1973 Revision Some of the pertinent dynamometer performance test criteria called for m this AAR Specification are as follows. 1 Instantaneous Retarding Force During 45 Minute Dynamometer Drag Test Drag Heavy load Light load Retarding Force 400 lbs min 300 lbs mm 2 Static Coefficient of Friction 9 Test Average--0 38 mm 3 Stop Distances From 90, 70, 50, 30, 10 mph Under Light and Heavy Brake Shoe Loads (all stop distances must be within varying tolerances) 4 Wear Loss Drag Tests (total)-O 60 in sup 3 max Test Stops (total per sequence)--1 20 in sup 3 max As used herein, the term "synthetic fiber" means fiber made from a substance which does not naturally occur in a fibrous state and includes glass, polyester and kaowool The term "synthetic fiber" excludes all forms of cellulose, which naturally occurs in a fibrous state, but which can also be processed into a different fibrous form (e g , rayon) Some example mixes used a single type of synthetic fiber, while others used several types of synthetic fibers in combination Other example mixes contained a mixture of synthetic and cellulose fibers All mixes were totally free of asbestos and lead Organic binders, such as styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and modified phenolic and cashew resins were used Cunng agents for the organic binders included sulfur, zinc oxide and hexamethylene tetramine http //patft uspto gov/netacgi/nph-Parser9Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Page 5 of 9 Ik number of filler materials were used in varying combinations to produce the necessary low wear rate, Tiardness and high coefficient of friction The fillers used were cast iron grit, kyanite, cashew nut particles, red iron oxide (hematite), black iron oxide, powdered alumina, graphite, barytes, coke, kaolin, cryolite, carbon black and zinc powder. Examples of the mixes formulated and tested are shown below and denoted Mixes A-R The compositions of ingredients are expressed in weight percentages Weight % MIX A Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina black iron oxide barytes coke MIX B Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite MIX C Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite MIX D Glass Fiber Organic Binder rubber resin 15 74 2 89 12 11 12 11 0 27 8 46 21 21 22 55 14 47 2 78 23 37 11 68 0 26 7 90 20 42 11 68 2 . 91 12 03 4 95 24 54 13 99 0 48 3 92 17 11 14 99 4 82 14 59 2 59 3 02 18 63 1 64 76 71 2 91 17 .25 1 62 78 22 1. 61 16 98 1 54 79 85 1 62 17 18 http //patft uspto gov/netacgi/nph-Parser9Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke MIX E Polyester Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite MIX F Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials kyanite hematite cashew particles powdered alumina graphite barytes coke MIX G Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite MIX H Fiber glass cellulose Organic Binder rubber resin Curative Agents Filler Materials graphite 24 75 14 11 0 26 7 65 16 22 15 12 10 98 7 95 13 36 20 60 0 53 8 73 19 10 11 44 5 35 16 68 3 06 12 84 16 04 1 28 0 28 6 40 22 44 16 04 14 95 2 74 23 02 11 51 0 26 5 74 20 12 14 38 2 87 3 06 0 53 6 64 11 17 6 99 3 08 78 13 0 71 18 93 1 24 79 11 3 20 19 74 1 74 75 32 2 87 17 69 1 56 77 90 3 59 17 81 2 39 76 22 Page 6 of 9 http //patft uspto go\7netacgi/nph-Parser9Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 barytes coke kaolin powdered alumina iron grit kyanite hematite MIX J Fiber glass cellulose Organic Binder rubber resin Curative Agents Filler Materials kyanite powdered alumina iron grit graphite barytes coke cryolite MIX L Fiber cellulose polyester kaowool Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite graphite barytes coke powdered alumina kaolin MIX M Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite carbon black MIX N Glass Fiber Organic Binder rubber resin 13 87 7 31 3 62 0 53 22 37 13 17 8 36 1 45 0 71 15 06 2 76 11 59 0 26 23 19 5 73 20 26 14 48 2 89 0 50 0 33 2 49 2 95 16 62 31 08 12 44 6 70 15 56 4 98 0 50 3 22 9 46 7 51 24 71 14 09 1 01 1 98 16 81 10 26 4 86 4 92 14 35 2 55 2 16 17 82 1 57 78 45 3 32 19 57 2 65 74 48 3 24 16 97 1.17 78 64 3 19 16 90 Page 7 of 9 http //path uspto gov/netacgi/nph-Parser?Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003  United States Patent 4,217,255 Curative Agents Filler Materials iron grit kyanite powdered alumina graphite barytes coke cryolite MIX 0 Glass Fiber Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite graphite barytes coke zinc powder MIX P Fiber glass cellulose Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite graphite barytes coke zinc powder MIX R Fiber glass cellulose Organic Binder rubber resin Curative Agents Filler Materials iron grit kyanite barytes coke powdered alumina carbon black 24 34 13 88 0 26 7 78 17 16 10 11 4 78 4 92 12 07 31 12 12 46 6 63 12 12 7 62 3 06 6 34 0 51 5 02 12 34 31 75 12 71 6 85 13 89 5 08 3 12 3 18 6 38 10 21 8 11 26 67 15 21 6 38 11 17 1 08 7 10 1 60 78 31 6 21 16 99 3.79 73 01 6 85 17 36 2 40 73 40 9 56 18 32 4 51 67 61 Page 8 of 9 The performance of these composition friction materials against the A A R standards is shown below, where P=passed test and F=failed test http //patft uspto gov/netacgi/nph-Parser?Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 *' United States Patent 4,217,255 TEST RESULTS-EXAMPLE MIXES Static Wear Loss Drag Tests Stop Distances Coeff of (in sup 3) Light Heavy Light Heavy Mix Friction Drag/Stops Drag Drag BSL BSL A 347 B 514 C 570 D 480 E 390 F 563 G 515 H 397 J 597 L 494 M 457 N 544 16/ 33 P P P P 09/ 33 P P P P 11/ 26 P P P P 23/ 56 P P P P 17/ 57 P P P P 33/ 18 P P P P 11/ 33 P P P P 23/ 56 P P P P 10/ 32 P P P P 17/1 03 P P P P 15/ 59 P P P P 12/ 31 P P P P Page 9 of 9 All of the above mixes passed all of the A A R performance tests, with the exception of Mix A which exhibited slightly low coefficients of friction Mix L showed a relatively high wear rate, although within ^he AAR standards It can be seen from the above test results that friction matenals made from compositions including vanous synthetic fibers along, in combination with other synthetic fiber, or in combination with cellulose fiber can meet ngorous AAR standards and exhibit low wear rates The best wear rates were exhibited by Mixes A, B, C, G and N, which contained from 1 61-3 19% of a single synthetic fiber, and by Mix J which contained a low total content fiber mixture of synthetic and cellulose fibers Overall fiber content ranged from 0 71% polyester (Mix E) to 9 56% glass and cellulose (Mix R) Binder content ranged from 16 90% (Mix N) to 19 74% (Mix F), while filler content was from 67 61% (Mix R) to 79.85% (Mix C) The amount and type of curative agents is mainly dependent on the amount and composition of the organic binder used In summation, I have discovered that composition friction matenals suitable for railroad use can be formulated, without the use of lead or asbestos, by using a relatively low content of various synthetic fibers alone, in combinations, or m combination with cellulose fiber if it k it k Images View Cart Add to Cart Prev 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