Abstract: A rubber composition of the present technology contains: diene rubber (A) containing a predetermined amount of specific conjugated diene rubber represented by a predetermined formula; silica having a CTAB adsorption specific surface area in a predetermined range; and a silane coupling agent represented by a predetermined formula.

Abstract: Provided is a rubber composition that can achieve excellent breaking resistance while having high operability. A rubber composition comprises: a rubber component containing a multicomponent copolymer that contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit; and an ?-olefin having a number-average molecular weight (Mn) of 50 to 1,000.

Abstract: [Object] To provide a friction material, which is manufactured by forming a non-asbestos-organic (NAO) friction material composition, used for a disc brake assembled in such as a passenger car, which does not degrade the inhibitory effect of rusting and prevents seizure due to corrosion even if the automotive while the parking brake in operation is left under a high humidity state for a long period of time. [Means to Resolve] A friction material, which is manufactured by forming the NAO friction material composition including a binder, a fiber base material, a friction modifier, a lubricant, a pH adjuster, and a filler, where the friction material composition contains 2-6 weight % of alkali metal salt and/or alkaline earth metal salt as the pH adjuster relative to the total amount of the friction material composition, 1-7 weight % of fibrillated organic fiber as the fiber base material relative to the total amount of the friction material composition, and 0-0.

Abstract: The present technology provides a rubber composition having: from 30 to 50 parts by mass of carbon black having a nitrogen adsorption specific surface area of from 100 to 130 m2/g, from 25 to 40 parts by mass of carbon black having a nitrogen adsorption specific surface area of from 37 to 60 m2/g, from 1.5 to 2.2 parts by mass of sulfur as a pure sulfur content, and from 110 to 200 mass % of a sulfenamide-based vulcanization accelerator relative to the pure sulfur content compounded in 100 parts by mass of diene rubber containing from 30 to 60 parts by mass of isoprene rubber and from 40 to 70 parts by mass of butadiene rubber.

Abstract: A rubber composition for tire tread or a rubber composition for tire sidewall, comprising one or more rubber components, and a composite powder which comprises a persimmon fruit extract and sodium carbonate and which is in an amount of 1.0 to 10 parts by mass when a total amount of the rubber component(s) is regarded as 100 parts by mass. In the rubber compositions, it is preferable that in the composite powder, a ratio by mass of the persimmon fruit extract to the sodium carbonate is from 1:1 to 5:1. Moreover, in the rubber compositions, it is preferable that when a total amount of the rubber component(s) is regarded as 100 parts by mass, an effective component amount of the persimmon fruit extract in the composite powder is from 0.01 to 8.0 parts by mass.

Abstract: The present disclosure relates to a rubber composition for tire tread and a tire manufactured by using the same, and the rubber composition for tire tread improves rolling resistance and abrasion resistant performance and can improve handling and braking performances on a wet road surface and an ice and snow road surface at the same time by comprising 100 parts by weight of raw rubber and 70 to 120 parts by weight of a reinforcing filler, wherein the raw rubber includes 0 to 50 parts by weight of natural rubber, 20 to 100 parts by weight of a melt grafting-functionalized styrene butadiene rubber, and 0 to 30 parts by weight of butadiene rubber.

Abstract: A friction material, such as those belonging to the NAO or LS classes. The friction material is substantially free from copper and includes non-spherical particles in the form of powders and/or fibres each constituted by a preferably ferrous metallic core and by an at least partial coating of core formed at least partially or totally by tin and/or tin compounds, such as intermetallic Fe—Sn compounds.

Abstract: Carbon blacks such as reinforcing-grade carbon blacks with high structure are described. The carbon black can have the following properties: a statistical thickness surface area (STSA) ranging from 80 m2/g to 150 m2/g, an oil absorption number (OAN) of at least 180 mL/100 g, and a crushed oil absorption number (COAN) of at least 110 mL/100 g. Rubber compounds which incorporate the carbon black also are described.

Abstract: The present invention is concerned with a frictional material composition not containing copper as an element or having the content of copper of 0.5 mass % or less, the composition containing (A) potassium titanate; and (B) one or more selected from the group consisting of lithium potassium titanate and magnesium potassium titanate, in a total content of the component (A) and the component (B) of 10 to 35 mass %, wherein on heating a molded product of the frictional material composition to 500° C. at a temperature rise rate of 10° C./min under an air atmosphere, the mass reduction rate is 5 to 20%.

Abstract: To provide a friction material used for a brake shoe of a drum brake for a passenger car, which continuously reduces generation of low frequency noise and provides excellent braking effectiveness and wear resistance and is manufactured by forming a friction material composition which contains no cleavage substance, 8-12 weight % of a phenolic thermosetting resin as the binder, 9-18 weight % of cashew dust as the organic friction modifier, 6-12 weight % of a rubber particle, where the total amount of the cashew dust and rubber particle is 18-25 weight %, and 4-10 weight % of the aluminum particle as the inorganic friction modifier, all relative to the total amount of the friction material composition. The friction material contains the phenolic thermosetting resin consists of a straight novolak phenolic resin and the unvulcanized nitrile rubber (NBR) particle.

Abstract: Provided is a rubber composition containing from 1 to 50 parts by mass of an organic microparticle having an average particle size of 0.001 to 100 ?m and having a crosslinked structure per 100 parts by mass of a diene rubber, the organic microparticle being a crosslinked microparticle of a copolymer formed from at least two types of segments having repeating units that are different each other, the at least two types of segments being formed from an oligomer or prepolymer having a functional group and having a molecular weight of 500 to 20000, and the functional group forming a crosslinked structure between the at least two types of segments.

Abstract: Processability and abrasion resistance are improved in a rubber composition having silica added thereto. The rubber composition for a tire comprises a diene rubber, silica and an ether ester that is monoester and/or diester of polyoxyalkylene glycerin fatty acid ester represented by the following formula (1): wherein R1, R2 and R3 each represent a hydrogen atom or an acyl group having a saturated or unsaturated alkyl group having 6 to 30 carbon atoms, provided that at least one of R1, R2 and R3 is an acyl group, R4, R5 and R6 each independently represent an alkylene group having 2 to 4 carbon atoms, a, b and c each independently represent an average number of moles added and 60 mass % or more of (R4O)a, (R5O)b and (R6O)c, consists of an oxyethylene group. A pneumatic tire manufactured using the rubber composition is disclosed.

Abstract: A diene-based rubber contains natural rubber and specific conjugated diene-based rubber. The content of the natural rubber in the diene-based rubber is 30 to 45 mass %. The content of the specific conjugated diene-based rubber in the diene-based rubber is 30 to 70 mass %. The specific conjugated diene-based rubber is conjugated diene-based rubber produced according to a specific production method. In the conjugated diene-based rubber, the aromatic vinyl unit content, the vinyl bond content, and the weight average molecular weight are within a predetermined range. The CTAB adsorption specific surface area of the silica is 180 m2/g or greater. The content of the silica is less than 60 parts by mass per 100 parts by mass of the diene-based rubber.

Abstract: A friction material comprising: (a) at least one lubricant, wherein the at least one lubricant includes an amount of graphite, and wherein at least about 30 percent by weight of the graphite has a particle size of greater than about 500 microns using a sieve analysis; (b) at least one metal containing constituent for imparting reinforcement, thermal conductivity, and/or friction when the friction material is brought into contact with a movable member, wherein the at least one metal containing constituent includes iron and an iron containing compound; (c) a micro-particulated material; (d) one or more filler materials; (e) optionally at least one processing aid; (f) a balance being an organic binder, wherein the organic binder has less than 1 percent by weight of free phenol; wherein the friction material is free of asbestos and substantially devoid of copper.

Abstract: A rubber composition for tires according to the present technology comprises: a natural rubber, a diene-based blended rubber containing a solution-polymerized SBR and an emulsion-polymerized SBR, an aromatic modified terpene resin, a silica, and a carbon black. The solution-polymerized SBR contains a specific solution-polymerized SBR having a block containing an isoprene unit at one terminal thereof and a modified terminal for silica at the other terminal thereof. The styrene unit content in the emulsion-polymerized SBR is from 35 to 50 mass %. The content of the natural rubber and the total content of the solution-polymerized SBR and the emulsion-polymerized SBR in the diene-based blended rubber are specified, and the contents of aromatic modified terpene resin, the silica, and the carbon black relative to the content of the diene-based blended rubber are specified.

Abstract: Provided are a rubber composition for tires that shows a balanced improvement in properties such as fuel economy, processability, heat aging resistance, abrasion resistance, wet-grip performance, performance on snow and ice, and handling stability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for tires, containing: a highly purified, modified natural rubber having a pH adjusted to 2 to 7, and a silica having a CTAB specific surface area of 180 m2/g or more and a BET specific surface area of 185 m2/g or more, and also relates to a pneumatic tire formed from the rubber composition.

Abstract: A rubber composition for a tire tread of the present technology comprises a rubber component containing not less than 30 mass % of a conjugated diene-based rubber (A), a silica (B), and a predetermined alkyltriethoxysilane (C), the conjugated diene-based rubber (A) containing not less than 5 mass % of a specified structural member (a), the silica (B) having a nitrogen adsorption specific surface area (N2SA) from 194 to 225 m2/g and a CTAB adsorption specific surface area (CTAB) from 180 to 210 m2/g, a content of the silica (B) being from 60 to 150 parts by mass per 100 parts by mass of the rubber component, and a content of the alkyltriethoxysilane (C) being from 2.5 to 8.0 mass % relative to the silica (B).

Abstract: A thermo-set resin composition comprising a Quebracho wood tannin extract, a furfuryl alcohol, a neoprene compound, a dimethicone, polyethylene glycol, abrasive particles, and a glycerol phosphate acidic ester and/or graphite. Further, a method of preparing the thermo-set resin composition including mixing Quebracho wood tannin extract with a furfuryl alcohol to form a primary mixture, adding additives and abrasive particles to the primary mixture, and reacting the primary mixture by adding a catalyst. The thermo-set resin composition is molded into a shape under heat and pressure to a Brinell hardness 8.5 daN/mm2 and 48 daN/mm2 and can be incorporated into a friction pad of a brake pad.

Abstract: Tire treads and tires having such tire treads are included, such treads manufactured with a rubber composition that includes mostly, if not entirely, a polybutadiene rubber having cis-1,4 bond content of at least 95%. The rubber composition further includes between 60 phr and 95 phr of a plasticizing resin having a Tg of at least 25° C. and between 0 phr and 15 phr of a liquid plasticizer. Additionally the rubber composition is reinforced with at least 90 phr of a silica reinforcing filler. Alternatively, in some embodiments, the rubber composition may be reinforced with an organic filler, an inorganic filler or combinations thereof. In some of these embodiments, the rubber composition includes at least 90 phr of such reinforcing filler.

Abstract: Disclosed are a modified conjugated diene polymer and a method for preparing the same. Provided are advantageously a modified conjugated diene polymer and a method for preparing the same which provide superior compatibility with an inorganic filler, heat generation, tensile strength and abrasion resistance, low fuel consumption and excellent resistance on wet roads.

Abstract: A rubber composition is provided that includes a partially halogenated diene polymer that has a controllable microstructure, and no more than about 50% of the n repeat units are in blocks of three or more consecutive units. In embodiments, a reinforcing filler is also included in the rubber composition. In embodiment, the rubber composition is formed into a tire component. A method of making the composition is also provided.

Abstract: A rubber compound for the manufacture of antistatic tires used in vehicles comprising a rubber component derived from epoxidized natural rubber, a white filler component for reducing rolling resistance of said tire, an electrically conductive filler component, and a vulcanization agent. An antistatic tire for vehicles comprising a body and a tread wherein said tread is produced from said rubber compound above.

Abstract: The present invention provides a copolymer of a conjugated diene compound and a non-conjugated olefin that is used for manufacturing a rubber excellent in crack growth resistance, heat resistance and ozone resistance and that includes a cis-1,4 bond at a unit derived from the conjugated diene compound, a rubber composition containing the copolymer, a rubber composition for tire treads using the rubber composition for tire tread members, a crosslinked rubber composition obtained by crosslinking the rubber composition, and a tire using the rubber composition or the crosslinked rubber composition. In the copolymer of a conjugated diene compound and a non-conjugated olefin, the cis-1,4 bond content of a unit derived from the conjugated diene compound is more than 92%.

Abstract: Disclosed are a modified conjugated diene polymer and a method for preparing the same. Provided are advantageously a modified conjugated diene polymer and a method for preparing the same which provide superior compatibility with an inorganic filler, heat generation, tensile strength and abrasion resistance, low fuel consumption and excellent resistance on wet roads.

Abstract: A tire rubber composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, a coupling agent providing the bonding between the inorganic filler and the diene elastomer, wherein the coupling agent is an azosilane compound of formula (I): (G1)3-a(G2)aSi—Z—NH—C(O)—N?N—C(O)—NH—Z—Si(G1)3-a(G2)a (I) wherein: G1, identical to or different, each represent a monovalent hydrocarbon group chosen from branched or unbranched, substituted or unsubstituted alkyls having from 1 to 18 carbon atoms, substituted or unsubstituted cycloalkyls or aryls having from 5 to 18 carbon atoms, G2, identical to or different, each represent a hydroxyl group or a monovalent group chosen from branched or unbranched, substituted or unsubstituted alkoxyls having from 1 to 18 carbon atoms, substituted or unsubstituted cycloalkoxyls having from 5 to 18 carbon atoms, Z represents a divalent linking group having from 1 to 18 carbon atoms, a is equal to 1, 2 or 3.

Abstract: A polymer having a carbon-carbon double bond in a main chain is decomposed by subjecting the carbon-carbon double bond to oxidative cleavage using an oxidizing agent such as periodic acid to decrease the molecular weight, polymer chains of the decomposed polymer are combined by changing acido-basic properties such that a system containing the decomposed polymer becomes basic when acidic and becomes acidic when basic, and a modified polymer in which the structure has been changed is obtained. By this, a functional group can be incorporated in the main chain structure of a polymer. A rubber composition comprising a rubber component containing the modified polymer, and a filler compounded therewith, and a pneumatic tire comprising the rubber composition are provided.

Abstract: A friction element for a synchronizing device as well as an apparatus for producing a friction element for a synchronizing device are disclosed.

Abstract: Method for preparing a silica/natural rubber masterbatch, including: doping the silica with magnesium; preparing at least one dispersion of the resulting doped silica in water; bringing a natural rubber field latex into contact with the aqueous doped-silica dispersion and mixing them together so as to obtain a coagulum; recovering the coagulum; and drying the recovered coagulum so as to obtain the masterbatch.

Abstract: Preparation of a masterbatch of diene elastomer and silica including preparing at least one silica dispersion in water; bringing into contact and mixing an elastomer latex and the aqueous silica dispersion in the presence of a metal salt in order to obtain a coagulum; and recovering the coagulum and drying the recovered coagulum in order to obtain the masterbatch. The molar content of zinc cations, defined as the number of moles of zinc cations of the zinc salt per BET unit area of the silica, is between 1.19*10?6 and 5.62*10?6 mol/m2.

Abstract: The present invention relates to a conjugated diene polymer end-modified with an alkoxysilane derivative. More particularly, the present invention relates to an end-modified conjugated diene polymer, wherein an alkoxysilane derivative having an ether group and a dialkylamino group is bonded as end modifier to an end of a conjugated diene polymer, which is useful as a rubber material for a tire tread owing to improved compatibility with an inorganic reinforcing agent and improves dynamic mechanical properties such as wet traction, rolling resistance, Mooney viscosity, processability, etc.

Abstract: A process for modifying natural rubber and modified natural rubber with improved processing performance. The process for modifying natural rubber includes at least the following process steps: comminuting the natural rubber in a first process step; blending and purifying the natural rubber in a second process step; further comminuting the natural rubber in a third process step; and, drying the natural rubber in a fourth process step. The modified natural rubber is modified by at least four process steps.

Abstract: This invention relates to a tire having a rubber tread containing functionalized carbon nanotubes and particulate reinforcement comprised of precipitated silica.

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of polymerizing monomer to form a reactive polymer, and reacting the reactive polymer with a polycyano compound.

Abstract: An elastomeric composition and method incorporating a hydrocarbon polymer modifier with improved permanence. The composition comprises elastomer, filler and silane-functionalized hydrocarbon polymer modifier (Si-HPM) adapted to couple the Si-HPM to the elastomer, filler or both, wherein the Si-HPM comprises an interpolymer of monomers chosen from piperylenes, cyclic pentadienes, aromatics, limonenes, pinenes, amylenes, and combinations thereof. The method comprises melt processing a mixture to form the elastomeric composition in the shape of an article, wherein the mixture comprises elastomer, Si-HPM, silica, bifunctional organosilane crosslinking agent; and curing the elastomeric composition to form the article. Also disclosed are a silylated hydrocarbon polymer modifier coupled with a bifunctional organosilane crosslinking agent, and a silica-coupled hydrocarbon polymer modifier coupled to the silica via the bifunctional organosilane crosslinking agent.

Abstract: A macromolecule includes a functional group including imine functionality bonded to a polymer chain. Where desired, the functional group also can contain additional (e.g., amine and/or silane) functionality. The material can be provided by reacting a polymer including carbonyl functionality with a compound including a primary amino group. The functional group can interact with particulate filler such as, e.g., carbon black and silica.

Abstract: A positive friction powder additive for modifying existing brake pad or brake shoe formulations to reduce squealing associated with braking. The positive friction powder additive comprises a friction modifier and a solid lubricant and is comprised of talc, barytes, aluminum oxide, and molybdenum disulphide. The positive friction powder additive can be formulated with binders and fillers to prepare a non-metallic brake pad or brake shoe formulation and a non-metallic brake pad or brake shoe. The positive friction powder additive, non-metallic brake pad or brake shoe formulation, and non-metallic brake pad or brake shoe have high and positive frictional characteristic which reduces vibrations and noise by reducing stick/slip oscillations by changing friction from negative to positive.

Abstract: A rubber composition for use in tire treads comprises a diene rubber including not less than 40% by weight of a modified conjugated diene polymer rubber and, per 100 parts by weight of the diene rubber, from 66 to 110 parts by weight of a filler. The filler comprises not less than 50% by weight of silica. The modified conjugated diene polymer rubber is obtained by copolymerizing a conjugated diene monomer unit and an aromatic vinyl monomer unit in a hydrocarbon solvent using an organic active metal compound as an initiator. A resulting active conjugated diene polymer chain thereof has a terminal modified group, obtained by reacting at least one type of compound having a functional group that is reactable with the active terminal of the polymer chain. Moreover, the terminal modified group has a functional group that interacts with the silica.

Abstract: The invention relates to a rubber composition that is free of zinc or that contains less than 0.5 phr of zinc, which can be used for the manufacture of tyres, based on at least: one diene elastomer; one sulphur-based crosslinking system; one inorganic filler as reinforcing filler; one blocked mercaptosilane of general formula I below: (HO)3-nR1n—Si—Z—S—C(?O)-A in which: R1, which are identical or different, each represent a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms; A represents hydrogen or a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms; Z represents a divalent bonding group comprising from 1 to 18 carbon atoms; n is an integer equal to 0, 1 or 2.

Abstract: The present invention provides a copolymer of a conjugated diene compound and a non-conjugated olefin that is used for manufacturing a rubber excellent in crack growth resistance, heat resistance and ozone resistance and that includes a cis-1,4 bond at a unit derived from the conjugated diene compound, a rubber composition containing the copolymer, a rubber composition for tire treads using the rubber composition for tire tread members, a crosslinked rubber composition obtained by crosslinking the rubber composition, and a tire using the rubber composition or the crosslinked rubber composition. In the copolymer of a conjugated diene compound and a non-conjugated olefin, the cis-1,4 bond content of a unit derived from the conjugated diene compound is more than 92%.

Abstract: A rubber composition comprises a diene rubber including not less than 25% by weight of a modified conjugated diene polymer rubber and, per 100 parts by weight of the diene rubber, from 25 to 65 parts by weight of a filler, the filler comprising not less than 50% by weight of silica. The silica has a DBP absorption number of 190 to 250 ml/100 g, an N2SA of 194 to 225 m/g, and a CTAB of 185 to 215 m2/g. A ratio of the N2SA to the CTAB is from 0.9 to 1.4. The modified conjugated diene polymer rubber has a terminal modified group including a functional group that interacts with the silica. In the modified conjugated diene polymer rubber, aromatic vinyl unit content is from 38% to 48% by weight, vinyl unit content is from 20% to 35%, and weight-average molecular weight is from 600,000 to 1,000,000.

Abstract: An automotive ceramic friction material free from asbestos and metal and preparation method thereof are provided. The material includes the following components: organic adhesive, reinforced fiber, friction-increasing agent, antifriction agent and fillers. The material has high coefficient of friction, stable braking performance, low heat fading, low wear resistance and long service life.

Abstract: The invention relates to a functionalized diene elastomer composed: a) of a diene elastomer functionalized, at the chain end or in the middle of the chain, by a tin functional group, exhibiting a monomodal distribution of molecular weights before functionalization and a polydispersity index before functionalization of less than or equal to 1.3, b) of a diene elastomer star-branched with a tin compound, exhibiting a monomodal distribution of molecular weights before star-branching and a polydispersity index before star-branching of less than or equal to 1.3, and c) of a content of less than 15% by weight, with respect to the total weight of the functionalized diene elastomer, of a non-tin-functional diene elastomer, the said diene elastomers a), b) and c) being, before optional functionalization or optional star-branching, the same in nature.

Abstract: This present invention relates to carbon nanotubes as fillers in composites with materials such as elastomers, thermosets and thermoplastics. A further feature of this invention relates to the development of a concentrate of carbon nanotubes with an elastomer wherein the concentrate can be further diluted with an elastomer and other polymers and fillers using conventional melt mixing.

Abstract: A composition includes a vulcanizable diene rubber, a silica filler, and a metal-functionalized polyisobutylene succinic anhydride derivative. In one embodiment the composition has a reduced amount of oil and may include no oil. A tire tread composition includes, a silica filler, a metal-functionalized polyisobutylene succinic anhydride derivative, a rubber matrix, an optional oil, and one or more components selected from the group consisting of carbon black, vulcanizing agent, vulcanization accelerator, tackifier resin, antioxidant, wax, peptizer, vulcanization retarder, activator, processing additive, plasticizer, pigments, and antiozonant. A method for making the rubber composition and the tire tread is also provided.

Abstract: A gelling agent, and a method of use for the same, for gelling a puncture repair material, the puncture repair material including a natural rubber latex, a resin emulsion, and an antifreezing agent, the gelling agent comprising a compound (?) of the following Formula (1). In the following Formula 1, R1 is an alkyl group having from 13 to 30 carbon atoms or an alkenyl group having from 13 to 30 carbon atoms.

Abstract: The invention discloses a copper-free ceramic friction material and a preparation method thereof. The friction material at least contains the following materials in mass content: 2-30% of alkaline earth-based metal compound and 2-30% of carbon fiber, wherein the alkaline earth-based metal compound is MxFeyTiOz, M is alkaline earth element Be, Mg, Ca, Sr or Ba, x is 0.2-2, y is 1-2, and z is 4-16. The friction material prepared according to the invention has excellent friction wear performance, high property of heat conductivity and excellent high temperature fading resistance. The temperature on the friction surfaces is effectively reduced during braking.

Abstract: The present invention is directed to a rubber composition comprising: a functionalized elastomer comprising: a polymeric backbone chain derived from a monomer comprising at least one conjugated diene monomer and optionally at least one vinyl aromatic monomer; and a functional group bonded to the backbone chain, the functional group comprising a multidentate ligand capable of complexing with a metal ion; and a metal ion. The invention is further directed to a pneumatic tire comprising the rubber composition.

Abstract: There is provided a friction material. The friction material includes a fibrous material, a friction modifier, and a binder. The friction material contains potassium titanate powders, steel fibers, calcium pyrophosphate and iron oxide. An amount of the potassium titanate powders may be 10 to 30 mass %. An amount of the steel fibers may be 1 to 7 mass %. An amount of the calcium pyrophosphate may be 5 to 20 mass %. An amount of the iron oxide may be 1 to 5 mass %.

Abstract: The present invention provides a rubber composition for an undertread, which has improved in processability, fuel economy, and tensile properties in a balanced manner, and also provides a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for an undertread, including: a rubber component containing a modified natural rubber having a phosphorus content of 200 ppm or less; and carbon black and/or a white filler, wherein the modified natural rubber is contained in an amount of 5% by mass or more per 100% by mass of the rubber component.

Abstract: In a wet friction material, inorganic filler of small particle size is added to fill clearances or space between fibers with the inorganic filler. The inorganic filler is attached to the fibers with each other to reinforce strength of the wet friction material when an impregnated resin is hardened. Absolute specific gravity of the inorganic filler is set at a fixed value so as to make its compounding quantity small, thereby assuring a pore diameter of a friction material substrate without filling pores of the friction material substrate with the inorganic filler.