WO2019171325A1 - Friction material composition and associated brake pad - Google Patents
Friction material composition and associated brake pad Download PDFInfo
- Publication number
- WO2019171325A1 WO2019171325A1 PCT/IB2019/051858 IB2019051858W WO2019171325A1 WO 2019171325 A1 WO2019171325 A1 WO 2019171325A1 IB 2019051858 W IB2019051858 W IB 2019051858W WO 2019171325 A1 WO2019171325 A1 WO 2019171325A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- friction material
- material composition
- composition according
- friction
- siloxane
- Prior art date
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 64
- 239000002783 friction material Substances 0.000 title claims abstract description 63
- 239000011230 binding agent Substances 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 10
- 239000010425 asbestos Substances 0.000 claims abstract description 8
- 229910052895 riebeckite Inorganic materials 0.000 claims abstract description 8
- 239000000314 lubricant Substances 0.000 claims abstract description 7
- 239000000945 filler Substances 0.000 claims abstract description 6
- 239000003607 modifier Substances 0.000 claims abstract description 6
- 229920000914 Metallic fiber Polymers 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 20
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims description 17
- 239000000843 powder Substances 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 9
- 239000003082 abrasive agent Substances 0.000 claims description 7
- 229920001568 phenolic resin Polymers 0.000 claims description 5
- 239000005011 phenolic resin Substances 0.000 claims description 5
- 229920006231 aramid fiber Polymers 0.000 claims description 4
- 239000000835 fiber Substances 0.000 claims description 4
- 229920000642 polymer Polymers 0.000 claims description 4
- 239000010959 steel Substances 0.000 claims description 4
- 229920005573 silicon-containing polymer Polymers 0.000 claims description 3
- 229910001018 Cast iron Inorganic materials 0.000 claims description 2
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 2
- 239000003822 epoxy resin Substances 0.000 claims description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 2
- 229920000647 polyepoxide Polymers 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims 1
- 239000011863 silicon-based powder Substances 0.000 claims 1
- 239000000654 additive Substances 0.000 description 9
- 230000000996 additive effect Effects 0.000 description 9
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229920002050 silicone resin Polymers 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000006399 behavior Effects 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000002657 fibrous material Substances 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 239000010445 mica Substances 0.000 description 2
- 229910052618 mica group Inorganic materials 0.000 description 2
- 229920003986 novolac Polymers 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 229920002379 silicone rubber Polymers 0.000 description 2
- 239000004945 silicone rubber Substances 0.000 description 2
- 239000000454 talc Substances 0.000 description 2
- 229910052623 talc Inorganic materials 0.000 description 2
- 239000010456 wollastonite Substances 0.000 description 2
- 229910052882 wollastonite Inorganic materials 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical class [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 239000010428 baryte Substances 0.000 description 1
- 229910052601 baryte Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- -1 chromite Chemical compound 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 239000011490 mineral wool Substances 0.000 description 1
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 1
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004634 thermosetting polymer Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 239000011135 tin Substances 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
- F16D69/02—Composition of linings ; Methods of manufacturing
- F16D69/025—Compositions based on an organic binder
- F16D69/026—Compositions based on an organic binder containing fibres
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2200/00—Materials; Production methods therefor
- F16D2200/006—Materials; Production methods therefor containing fibres or particles
- F16D2200/0065—Inorganic, e.g. non-asbestos mineral fibres
Definitions
- the present invention relates to a friction material composition that is particularly suitable for the manufacturing of friction layers/blocks for friction elements such as braking elements, for example vehicle brake pads or shoes, and/or clutch discs.
- the invention further relates to an associated brake pad manufactured using such a friction material composition.
- the friction material composition of the present invention is suitable for the manufacture of asbestos free friction materials, having different compositions and performance, wherein the phenomenon known as "creep groan" is either limited or absent.
- Modern friction materials that are free of asbestos fibers and heavy metals, such as copper and alloys thereof, include five classes of components: a fibrous material consisting of inorganic and/or organic and/or metallic fibers, a binder, a "filler", one or more lubricants or friction modifiers, one or more abrasives.
- Fibrous materials that substitute asbestos are both inorganic, such as rock fiber or rock wool, wollastonite, glass fibers, and organic, such as aramid fibers and carbon fibers, or metallic, such as steel fibers.
- the binder is usually a thermosetting polymer, such as for example based on phenolic resins.
- the filler such as barite (barium sulfate) , calcium carbonate, talc, magnesium oxide, ver iculite; as the abrasive, zirconium silicate, zirconium oxide, alumina, silicon carbide, mica; as the friction modifier, metal sulfides such as molybdenum disulfide, iron sulfides, copper, tin, graphite and/or coke.
- Other classes of materials are then added in smaller percentages such as for example rubber in powder or granule form, "friction dust", other organic materials .
- the brake pads produced with these friction materials are subject to the so-called "creep groan” phenomenon.
- This phenomenon occurs in vehicles and consists in the low-frequency vibration of the frame that is found with very low pressure being exerted by the brake pads and at extremely low speed, giving the driver a very uncomfortable feeling.
- EP 959262 - in the name of Hitachi Chemical refers to a pad for a disk brake capable of reducing creep groan using a composition containing a fibrous base material, with the exception of asbestos, a binder and a friction adjusting agent, wherein the binder is entirely or in part consisting of a modified silicone resin and wherein, in combination, the composition of the friction material contains between 0.5 and 20% by volume of a zeolite as part of the friction adjustment agent, the modified silicone resin being contained within the composition of the friction material in the measure of 3% to 30% by volume of the total composition.
- the modified silicone resin is obtained by means of the reaction of an oil or a silicone rubber with a phenolic resin of the novolak type.
- JP 2002266915 - in the name of Hitachi Chemical relates to a friction material composition that is similar to EP959262, with the difference that, together with the modified silicone resin obtained by means of the reaction of oil or silicone rubber with a phenolic resin of the novolak type, an abrasive is used, having a Mosh hardness greater than 7.
- EP0821711B1 - in the name of Ameron Int. Corp. relates to a phenol-siloxane resin composition for the production of generic high impact resistance plastic products. Brake pads are also amongst the products mentioned. In this case, the phenol-siloxane resin constitutes the entire binder of the brake pad. It does not however mention any advantages in relation to the presence of siloxane as regards performance when used in brake pads.
- the object of the present invention is to provide a friction material composition to be used for the manufacturing of friction layers/blocks for friction elements such as brake elements, for example vehicle brake pads or shoes, and/or clutch discs, which when in use is not subject to the creep groan phenomenon, or that is subject to it in a reduced and negligible manner, and that contemporaneously is suitable for industrial production on a large scale and has tribological characteristics that are comparable to those of existing friction materials.
- brake elements for example vehicle brake pads or shoes
- clutch discs which when in use is not subject to the creep groan phenomenon, or that is subject to it in a reduced and negligible manner, and that contemporaneously is suitable for industrial production on a large scale and has tribological characteristics that are comparable to those of existing friction materials.
- a particular object of the invention is to identify, other than the presence of specific components within the friction material composition, any constructive parameters that make it possible to mitigate or eliminate the creep groan phenomenon, without requiring changes to known friction material compositions that may affect their braking performance on the vehicle or that may alter the behavior thereof in an unpredictable way.
- the invention therefore relates to a friction material composition to be used for manufacturing friction layers/blocks for friction elements such as braking elements, in particular brake pads, and to an associated brake pad, as defined within the attached claims.
- the invention also relates to a braking system comprising an element to be braked consisting of a brake disk or shoe made of cast iron or steel and at least one braking element consisting of a brake pad or shoe suitable for cooperating by means of friction with the element to be braked, wherein the braking element has a friction layer or block intended to cooperate with the element to be braked manufactured with the friction material composition according to the invention.
- the friction material according to the invention comprises as the composing materials thereof: inorganic and/or organic and/or metallic fibers; a binder; at least one friction modifier or lubricant, for example including sulfides; and at least one filler or abrasive.
- the asbestos free friction material composition has the composing materials thereof, including inorganic and/or organic and/or metallic fibers, at least a binder, at least a friction modifier or lubricant and at least a filler or abrasive, as well as the respective relative quantities of such composing material, chosen in such a way that, after curing, i.e., after a thermal forming treatment under pressure with subsequent crosslinking of the binder, the friction material composition forms a friction material block having a porosity of between 5 and 40% and a hydrophobicity (defined as will be seen) of more than (i.e. greater than) 20 minutes.
- the composing materials thereof including inorganic and/or organic and/or metallic fibers, at least a binder, at least a friction modifier or lubricant and at least a filler or abrasive, as well as the respective relative quantities of such composing material, chosen in such a way that, after curing, i.e., after a thermal forming treatment under pressure with
- the friction material composition forms a friction material block having a porosity of between 10 and 30%.
- the friction material composition comprises an additive in powder form consisting of silica particles coated with a siloxane polymer, which additive is present in an amount ranging from 0.1% to 5% by volume, the percentage being calculated based upon the total amount of the composition.
- the polymer siloxane is a methyl-silicone resin or a halogen free siloxane and functionalized methyl-acrylate.
- the additive is silica powder coated with siloxane and the total content thereof is, as indicated above, between 0.1 and 5% by volume, the percentage being calculated based upon the total amount of the composition.
- the binder consists of a phenolic or epoxy resin.
- the ratio between the abrasives and lubricants is between 3 and 10 and is preferably equal to 6.
- the friction material composition according to the invention comprises an aramid fiber, the ratio between the binder and the aramid fiber being between 0.5 and 8% by volume, and is preferably equal to 5.
- FIG. 1 illustrates a graph showing values related to the hydrophobicity of different compared friction material mixtures or compositions
- Figure 2 illustrates a graph showing values related to the porosity of the same compared friction material mixtures or compositions of figure 1;
- FIGS 3, 5 and 4, 6 illustrate an extract of the results of an AK-Master test performed on brake pads manufactured, respectively, with compounds or friction material compositions according to the invention and with traditional compounds or friction material compositions.
- Mild abrasives Mohs 1-3: talc, calcium hydroxide, potassium titanate, mica, kaolin
- Medium abrasives Mohs 4-6: barium sulfate, magnesium oxide, calcium fluoride, calcium carbonate, wollastonite, calcium silicate, iron oxide, silica, chromite, zinc oxide
- the hydrophobic additive consists of a silica powder coated with a siloxane consisting of a methyl-silicone polymer.
- the friction material compositions according to Table 1 were molded onto identical metal substrates and cured in a conventional manner, in order to form identical brake pads, except for the chemical composition of the friction material.
- the brake pad pressing was performed at a temperature of between 60 and 200°C at a pressure from 150 to
- the resulting pressed article is typically post-cured by means of heat treatment from 150 to 400 °C for a duration of between 10 minutes to 10 hours, it is then spray painted or powder-painted, kiln-dried and possibly machined where necessary to produce the final product.
- the effective braking area of each single pad is 26.8 cm 2 .
- Each pad is tested by means of a mercury porosi eter, according to the ASTM D 4404-84 Standard.
- the evaluation is performed on the previously obtained brake pads, mounted on a vehicle, by means of a "Mojacar" durability test, assigning a rating - the higher it is the lower the creep groan .
- the creep groan noise is evaluated in performing different braking operations in the morning (under cold conditions) by putting the vehicle on a ramp;
- the brakes are applied by pressing on the brake pedal with the vehicle pointing down the ramp (12% slope) with the engine off, after having applied and then released the handbrake;
- the initial pressure within the brake circuit is evaluated at about 10-15 bar; with the car stopped on the ramp, the brake is gradually released and creep groan appears when the pressure within the brake circuit decreases to around 5-7 bars;
- the ambient temperature at which the test is performed is between about 15-20 °C (early in the morning) and the relative humidity varies from 30 to 98%.
- Brake pads made with the friction material compositions of the preceding examples were subjected to various standard AK- Master tests according to the SAE J2522 standard. Summary and significant charts of the tests performed are shown in Figures 3 to 6.
- both the brake pads made according to the invention wherein the friction material composition includes the silica powder additive coated with a siloxane and which has the values of porosity and hydrophobicity highlighted in the previous examples
- the "traditional" brake pads, made with the substantially identical friction material composition, but lacking the hydrophobic additive according to the invention and therefore having hydrophobicity values egual to or less than 20 minutes have entirely comparable braking behaviors.
- an additive consisting of silica powder coated with a siloxane, which makes it possible to obtain a hydrophobicity of more than 20 minutes accompanied by low or absent creep groan noise and a porosity that is substantially unaffected, does not involve a significant variation, in a particular a decline, in braking performance.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
Asbestos free friction material composition including inorganic and/or organic and/or metallic fibers, at least a binder, at least a friction or lubricant modifier and at least a filler or abrasive, wherein these composing materials and the respective relative quantities are chosen in such a way that, after curing, the friction material composition forms a friction material block having a porosity of between 5 and 40% and a hydrophobicity of more than 20 min.
Description
FRICTION MATERIAL COMPOSITION AND ASSOCIATED BRAKE PAD
Cross-reference to related applications
This application claims priority from Italian Patent Application No. 102018000003343 filed on 07/03/2018, the disclosure of which is incorporated by reference.
Technical Field of the Invention
The present invention relates to a friction material composition that is particularly suitable for the manufacturing of friction layers/blocks for friction elements such as braking elements, for example vehicle brake pads or shoes, and/or clutch discs. The invention further relates to an associated brake pad manufactured using such a friction material composition.
The friction material composition of the present invention is suitable for the manufacture of asbestos free friction materials, having different compositions and performance, wherein the phenomenon known as "creep groan" is either limited or absent.
Prior Art
Modern friction materials that are free of asbestos fibers and heavy metals, such as copper and alloys thereof, include five classes of components: a fibrous material consisting of inorganic and/or organic and/or metallic fibers, a binder, a "filler", one or more lubricants or friction modifiers, one or more abrasives. Fibrous materials that substitute asbestos are both inorganic, such as rock fiber or rock wool, wollastonite, glass fibers, and organic, such as aramid fibers and carbon fibers, or metallic, such as steel fibers. The binder is usually a thermosetting polymer, such as for example based on phenolic resins. Various materials are used as the filler, such as barite (barium sulfate) , calcium carbonate, talc, magnesium oxide, ver iculite; as the abrasive, zirconium silicate, zirconium oxide, alumina, silicon carbide, mica; as the friction modifier, metal sulfides such as molybdenum disulfide, iron sulfides, copper, tin, graphite and/or coke. Other classes of materials
are then added in smaller percentages such as for example rubber in powder or granule form, "friction dust", other organic materials .
The brake pads produced with these friction materials are subject to the so-called "creep groan" phenomenon. This phenomenon occurs in vehicles and consists in the low-frequency vibration of the frame that is found with very low pressure being exerted by the brake pads and at extremely low speed, giving the driver a very uncomfortable feeling. It is the classic example of a self-excited braking vibration caused by the so-called "stick-slip" effect, i.e., by repeated "sticking" and subsequent slippage of the brake pad on the brake disc, or by the repeated passage between dynamic friction and static friction .
Several proposals for solutions are known in the art in order to reduce this phenomenon.
EP 959262 - in the name of Hitachi Chemical: refers to a pad for a disk brake capable of reducing creep groan using a composition containing a fibrous base material, with the exception of asbestos, a binder and a friction adjusting agent, wherein the binder is entirely or in part consisting of a modified silicone resin and wherein, in combination, the composition of the friction material contains between 0.5 and 20% by volume of a zeolite as part of the friction adjustment agent, the modified silicone resin being contained within the composition of the friction material in the measure of 3% to 30% by volume of the total composition. The modified silicone resin is obtained by means of the reaction of an oil or a silicone rubber with a phenolic resin of the novolak type.
JP 2002266915 - in the name of Hitachi Chemical: relates to a friction material composition that is similar to EP959262, with the difference that, together with the modified silicone resin obtained by means of the reaction of oil or silicone rubber with a phenolic resin of the novolak type, an abrasive is used, having a Mosh hardness greater than 7.
Finally, EP0821711B1 - in the name of Ameron Int. Corp. relates to a phenol-siloxane resin composition for the production of generic high impact resistance plastic products. Brake pads are also amongst the products mentioned. In this case, the phenol-siloxane resin constitutes the entire binder of the brake pad. It does not however mention any advantages in relation to the presence of siloxane as regards performance when used in brake pads.
Summary of the Invention
The object of the present invention is to provide a friction material composition to be used for the manufacturing of friction layers/blocks for friction elements such as brake elements, for example vehicle brake pads or shoes, and/or clutch discs, which when in use is not subject to the creep groan phenomenon, or that is subject to it in a reduced and negligible manner, and that contemporaneously is suitable for industrial production on a large scale and has tribological characteristics that are comparable to those of existing friction materials.
A particular object of the invention is to identify, other than the presence of specific components within the friction material composition, any constructive parameters that make it possible to mitigate or eliminate the creep groan phenomenon, without requiring changes to known friction material compositions that may affect their braking performance on the vehicle or that may alter the behavior thereof in an unpredictable way.
The invention therefore relates to a friction material composition to be used for manufacturing friction layers/blocks for friction elements such as braking elements, in particular brake pads, and to an associated brake pad, as defined within the attached claims.
The invention also relates to a braking system comprising an element to be braked consisting of a brake disk or shoe made of cast iron or steel and at least one braking element consisting of a brake pad or shoe suitable for cooperating by means of
friction with the element to be braked, wherein the braking element has a friction layer or block intended to cooperate with the element to be braked manufactured with the friction material composition according to the invention.
In particular, the friction material according to the invention comprises as the composing materials thereof: inorganic and/or organic and/or metallic fibers; a binder; at least one friction modifier or lubricant, for example including sulfides; and at least one filler or abrasive.
According to the main characteristic of the invention, the asbestos free friction material composition has the composing materials thereof, including inorganic and/or organic and/or metallic fibers, at least a binder, at least a friction modifier or lubricant and at least a filler or abrasive, as well as the respective relative quantities of such composing material, chosen in such a way that, after curing, i.e., after a thermal forming treatment under pressure with subsequent crosslinking of the binder, the friction material composition forms a friction material block having a porosity of between 5 and 40% and a hydrophobicity (defined as will be seen) of more than (i.e. greater than) 20 minutes.
In particular, after curing the friction material composition forms a friction material block having a porosity of between 10 and 30%.
According to an aspect of the invention, the friction material composition comprises an additive in powder form consisting of silica particles coated with a siloxane polymer, which additive is present in an amount ranging from 0.1% to 5% by volume, the percentage being calculated based upon the total amount of the composition.
The polymer siloxane is a methyl-silicone resin or a halogen free siloxane and functionalized methyl-acrylate.
Preferably, the additive is silica powder coated with siloxane and the total content thereof is, as indicated above, between 0.1 and 5% by volume, the percentage being calculated
based upon the total amount of the composition.
The binder consists of a phenolic or epoxy resin.
The ratio between the abrasives and lubricants is between 3 and 10 and is preferably equal to 6.
The friction material composition according to the invention comprises an aramid fiber, the ratio between the binder and the aramid fiber being between 0.5 and 8% by volume, and is preferably equal to 5.
By virtue of the selection of the parameters indicated above, i.e. by means of a combination of a selected porosity value combined with a selected value of hydrophobicity, measured, as will be seen, as the penetration time of a drop of water, surprisingly a net reduction in the "creep groan" phenomenon is obtained, reducing it to levels that are totally negligible and acceptable to the user. The net reduction in such a phenomenon occurs with different compositions of friction materials of differing natures, for example of the so-called "copper-free" or NAO or LS "low steel" or "semi met" type, all of which are asbestos free.
These implementation parameters are obtained, according to one exemplary and non-limiting embodiment of the invention, by means of the use of an additive consisting of silica powder covered with a siloxane polymer, which is then included within the friction material composition of the invention.
It is understood that the combination of physical parameters of the friction material obtainable from the friction material composition of the invention that, it has been surprisingly discovered, makes a dramatic reduction in creep groan possible, is independent of the specific chemical composition of the friction material composition and may possibly be obtainable also by acting upon other components of the composition.
Brief description of Figures
Further characteristics and advantages of the present invention will become clear from the following description of its exemplary non-limiting embodiments given purely by way of
example and with reference to the figures of attached drawings, in which:
- Figure 1 illustrates a graph showing values related to the hydrophobicity of different compared friction material mixtures or compositions;
- Figure 2 illustrates a graph showing values related to the porosity of the same compared friction material mixtures or compositions of figure 1; and
- Figures 3, 5 and 4, 6 illustrate an extract of the results of an AK-Master test performed on brake pads manufactured, respectively, with compounds or friction material compositions according to the invention and with traditional compounds or friction material compositions.
Detailed Description
Example 1
Various friction material compositions of two different types were prepared, as indicated in Table 1.
For each of the two families (known) of friction material compositions a reference was prepared (ref. in Table 1) according to the known composition currently in use and a same composition produced according to the parameters of the invention .
Table 1
• Mild abrasives (Mohs 1-3) : talc, calcium hydroxide, potassium titanate, mica, kaolin
• Medium abrasives (Mohs 4-6) : barium sulfate, magnesium oxide, calcium fluoride, calcium carbonate, wollastonite, calcium silicate, iron oxide, silica, chromite, zinc oxide
• Strong abrasives (Mohs 7-9) : silicon carbide, zirconium sand (zirconium oxide), zirconium silicate, zirconia, corundum, alumina, mullite.
The hydrophobic additive consists of a silica powder coated with a siloxane consisting of a methyl-silicone polymer.
Example 2
The friction material compositions according to Table 1 were molded onto identical metal substrates and cured in a conventional manner, in order to form identical brake pads, except for the chemical composition of the friction material.
In particular, the brake pad pressing was performed at a temperature of between 60 and 200°C at a pressure from 150 to
1800 kg/cm2 for a duration of between 3 and 10 minutes or else in preforming the mixing within a die and thereafter pressing at a temperature from 130 to 180 °C at a pressure from 150 to 500 kg/cm2 (14.7-49 MPa) for a duration of from 3 to 10 minutes.
The resulting pressed article is typically post-cured by means of heat treatment from 150 to 400 °C for a duration of between 10 minutes to 10 hours, it is then spray painted or powder-painted, kiln-dried and possibly machined where necessary to produce the final product.
The effective braking area of each single pad is 26.8 cm2.
The brake pads thus obtained by means of the friction material compositions numbered from 1 to 4 of Table 1, were subjected to the following tests.
A- Hydrophobicity test
(Falling water adsorption test)
The following operations were performed on each brake pad
constituting a test sample:
- Blowing and cleaning the raised surface of the brake pad (surface intended to come into contact with the brake disc) ;
- Drying the sample at 105 °C for 2 hours;
- Cooling the sample down to a temperature of 10-30 °C;
- Applying to a same point of the brake pad 20 +/- 5 pL of distilled water;
- Measuring the period of time required for complete absorption;
If necessary, repeating the measurements at different depths, removing the surface layer of the brake pad and repeating the previous operations.
B- Porosity Measurement
Each pad is tested by means of a mercury porosi eter, according to the ASTM D 4404-84 Standard.
C- Protocol Measurement of the Creep Groan
The evaluation is performed on the previously obtained brake pads, mounted on a vehicle, by means of a "Mojacar" durability test, assigning a rating - the higher it is the lower the creep groan .
- The vehicle is left in the garage during the night without applying the hand brake (the brake pad and disc are uncoupled) ;
- The creep groan noise is evaluated in performing different braking operations in the morning (under cold conditions) by putting the vehicle on a ramp;
- The brakes are applied by pressing on the brake pedal with the vehicle pointing down the ramp (12% slope) with the engine off, after having applied and then released the handbrake;
- The initial pressure within the brake circuit is evaluated at about 10-15 bar; with the car stopped on the ramp, the brake is gradually released and creep groan appears when the pressure within the brake circuit
decreases to around 5-7 bars;
The ambient temperature at which the test is performed is between about 15-20 °C (early in the morning) and the relative humidity varies from 30 to 98%.
The results of the test are given in Table 2.
Table 2
From the data in Table 2 it is evident that a high hydrophobicity (more than 20 minutes) accompanied by a suitable porosity (by maintaining a substantially unaltered porosity) makes it possible to drastically reduce the creep groan noise in both families of friction material compositions.
The tests were then repeated using various known compositions, with or without the addition of the hydrophobic additive consisting of silica powder coated with a siloxane consisting of a methyl-silicone polymer, or a halogen free siloxane and functionalized methyl-acrylate, obtaining results comparable to those of Table 2.
Example 3
Brake pads made with the friction material compositions of the preceding examples were subjected to various standard AK- Master tests according to the SAE J2522 standard. Summary and significant charts of the tests performed are shown in Figures 3 to 6.
As can immediately be appreciated, both the brake pads made according to the invention, wherein the friction material composition includes the silica powder additive coated with a siloxane and which has the values of porosity and hydrophobicity highlighted in the previous examples, and the "traditional" brake pads, made with the substantially identical friction material composition, but lacking the hydrophobic additive
according to the invention and therefore having hydrophobicity values egual to or less than 20 minutes, have entirely comparable braking behaviors.
Conclusions
Therefore, the addition of an additive consisting of silica powder coated with a siloxane, which makes it possible to obtain a hydrophobicity of more than 20 minutes accompanied by low or absent creep groan noise and a porosity that is substantially unaffected, does not involve a significant variation, in a particular a decline, in braking performance.
The objectives of the invention are therefore fully achieved.
Claims
1. Asbestos free friction material composition comprising, as composing materials thereof inorganic and/or organic and/or metallic fibers, at least a binder, at least a friction modifier or lubricant and at least a filler or abrasive, characterized in that the composing materials and the respective relative quantities are chosen in such a way that, after curing, the friction material composition forms a friction material block having a porosity of between 5 and 40% and a hydrophobicity of more than 20 minutes.
2. Friction material composition according to claim 1, characterized in that after curing the friction material composition forms a friction material block having a porosity of between 10 and 30% and a hydrophobicity of greater than 20 minutes .
3. Friction material composition according to claim 1 or 2, characterized in that it comprises silicon powder coated with a siloxane.
4. Friction material composition according to one of the preceding claims, characterized in that it comprises from 0.1% to 5% by volume of silica powder coated with a siloxane, the percentage being calculated based upon the total amount of the composition .
5. Friction material composition according to one of the preceding claims, characterized in that the siloxane is a methyl-silicone polymer.
6. Friction material composition according to one of the claims 1 to 4, characterized in that the siloxane is a halogen- free and methyl acrylate-functionalized siloxane.
7. Friction material composition according to one of the preceding claims, characterized in that the total content of silica powder covered with a siloxane polymer is between 0.1 and 5% by volume, the percentage being calculated based upon the
total amount of the composition.
8. Friction material composition according to one of the preceding claims, characterized in that the binder consists of a phenolic or epoxy resin
9. Friction material composition according to one of the preceding claims, characterized in that the ratio between the abrasives and lubricants is between 3 and 10.
10. Friction material composition according to one of the preceding claims, characterized in that it comprises an ara id fiber, the volume ratio between the binder and the aramid fiber being between 0.5 and 8.
11. Brake pad including a friction material block made with the friction material composition according to one of the claims from 1 to 10.
12. Braking system comprising an element to be braked consisting of a brake disc or shoe made of cast iron or steel and at least one braking element consisting of a brake pad or shoe, adapted to cooperate by friction with the element to be braked, characterized in that the braking element has a friction layer or block intended to cooperate with the element to be braked that is made with the friction material according to one of the claims from 1 to 10.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT102018000003343A IT201800003343A1 (en) | 2018-03-07 | 2018-03-07 | COMPOSITION OF FRICTION MATERIAL AND ASSOCIATED BRAKE PAD |
| IT102018000003343 | 2018-03-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2019171325A1 true WO2019171325A1 (en) | 2019-09-12 |
Family
ID=62386789
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2019/051858 WO2019171325A1 (en) | 2018-03-07 | 2019-03-07 | Friction material composition and associated brake pad |
Country Status (2)
| Country | Link |
|---|---|
| IT (1) | IT201800003343A1 (en) |
| WO (1) | WO2019171325A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022058942A1 (en) * | 2020-09-17 | 2022-03-24 | Itt Italia S.R.L. | Friction material block, in particular for equipping brake pads and associated brake pad and method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003003155A (en) * | 2001-06-20 | 2003-01-08 | Aisin Seiki Co Ltd | Friction material |
| EP1521010A2 (en) * | 2003-10-03 | 2005-04-06 | BorgWarner Inc. | Layered friction material |
| US20180017122A1 (en) * | 2016-07-15 | 2018-01-18 | Borgwarner Inc. | Friction material |
-
2018
- 2018-03-07 IT IT102018000003343A patent/IT201800003343A1/en unknown
-
2019
- 2019-03-07 WO PCT/IB2019/051858 patent/WO2019171325A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003003155A (en) * | 2001-06-20 | 2003-01-08 | Aisin Seiki Co Ltd | Friction material |
| EP1521010A2 (en) * | 2003-10-03 | 2005-04-06 | BorgWarner Inc. | Layered friction material |
| US20180017122A1 (en) * | 2016-07-15 | 2018-01-18 | Borgwarner Inc. | Friction material |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022058942A1 (en) * | 2020-09-17 | 2022-03-24 | Itt Italia S.R.L. | Friction material block, in particular for equipping brake pads and associated brake pad and method |
Also Published As
| Publication number | Publication date |
|---|---|
| IT201800003343A1 (en) | 2019-09-07 |
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