Friction member, friction material composition, friction material, and vehicle

Abstract

A friction member having a friction material and a backing metal, wherein the friction material does not contain copper, or if it does contain copper, the copper content is less than 0.5 mass % as copper element, and the specific surface area is 15 to 100 m 2 The present invention relates to a friction member containing graphite having a surface roughness of 1 / g.

Description

Technical Field

[0001] The present invention relates to a friction member, a friction material composition, a friction material, and a vehicle.

Background Art

[0002] Conventionally, asbestos has been used in friction materials. However, in recent years, the harmfulness of asbestos has become a problem, and its use has been restricted. Friction materials are roughly classified into semi-metallic materials containing 30 to 60% by mass of steel fibers as a fiber base material to replace asbestos, low-steel materials containing less than 30% by mass of steel fibers, and NAO (Non-Asbestos Organic) materials containing no steel fibers. However, friction materials containing a trace amount of steel fibers may sometimes be classified as NAO materials.

[0003] For this NAO material, copper (including copper alloys) such as fibers and powders has been used for the purpose of imparting thermal conductivity and improving wear resistance. However, it has been suggested that friction materials containing copper contain a large amount of copper in the wear powder generated by braking, which may cause pollution of rivers, lakes, oceans, etc. Therefore, in some parts of North America, laws have been enacted to prohibit the sale and installation in new vehicles of friction materials containing 5% by mass or more of copper after 2021 and 0.5% by mass or more of copper after 2023. Therefore, in order to obtain friction materials that can be used in the United States and other foreign countries, there is a requirement to not contain copper or to significantly reduce the copper content.

[0004] Compositions that do not contain copper have problems such as an increase in the wear amount of the friction material, generation of brake vibration, etc. because the heat at the friction interface does not diffuse during braking at high temperatures due to a decrease in thermal conductivity. Patent Document 1 proposes a method of adding graphite having high thermal conductivity for the purpose of improving thermal conductivity, wear resistance, etc. in a friction material that does not contain copper.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-138273 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, according to the study by the present inventor, it has been found that there is room for improvement in the mechanical strength, particularly the shear strength, of a friction material containing graphite. That is, while a certain amount of graphite with high thermal conductivity is incorporated, it is desired to develop a friction material composition capable of further increasing the shear strength.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a friction material composition capable of providing a friction material having excellent shear strength using a material with a small environmental load, a friction material using the friction material composition, a friction member, and a vehicle. [Means for Solving the Problems]

[0008] As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by the following present invention, and has completed the present invention. The present invention relates to the following [1] to

[19] . [1] A friction member having a friction material and a backing plate, wherein the friction material contains no copper or, even if it contains copper, the copper content is less than 0.5% by mass as copper element, and has a specific surface area of 15 to 100 m 2 / g and contains graphite, the friction member. [2] The friction member according to the above [1], wherein the friction material contains 0.1 to 10% by mass of the graphite. [3] The friction member according to the above [1] or [2], wherein the friction material further contains 4 to 30% by mass of at least one fiber base material selected from the group consisting of organic fibers and inorganic fibers. [4] The friction member according to the above [3], wherein the friction material contains 6 to 25% by mass of mineral fibers as the inorganic fibers. [5] The friction member according to any one of [1] to [4] above, wherein the friction material further contains one or more selected from the group consisting of a binder, an organic filler, and an inorganic filler. [6] The friction member according to any one of [1] to [5] above, wherein the specific surface area of the graphite is 15 to 50 m 2 / g. [7] The friction member according to any one of [1] to [6] above, wherein the average particle diameter of the graphite is 2 to 200 μm. [8] The friction member according to any one of [1] to [7] above, which is for a disc brake pad or a drum brake lining. [9] A vehicle equipped with the friction member according to any one of [1] to [8] above.

[10] A friction material composition that does not contain copper, or even if it contains copper, the copper content is less than 0.5% by mass as elemental copper, and contains graphite with a specific surface area of 15 to 100 m 2 / g.

[11] The friction material composition according to

[10] above, which contains 0.1 to 10% by mass of the graphite.

[12] The friction material composition according to

[10] or

[11] above, which further contains 4 to 30% by mass of one or more fiber base materials selected from the group consisting of organic fibers and inorganic fibers.

[13] The friction material composition according to

[12] above, which contains 6 to 25% by mass of mineral fibers as the inorganic fibers.

[14] The friction material composition according to any one of

[10] to

[13] above, which further contains one or more selected from the group consisting of a binder, an organic filler, and an inorganic filler.

[15] The friction material composition according to any one of

[10] to

[14] above, wherein the specific surface area of the graphite is 15 to 50 m 2 / g.

[16] The friction material composition according to any one of

[10] to

[15] above, wherein the average particle diameter of the graphite is 2 to 200 μm.

[17] The friction material composition according to any one of

[10] to

[16] above, which is for a disc brake pad or a drum brake lining.

[18] A friction material comprising the friction material composition according to any one of

[10] to

[17] above.

[19] A vehicle equipped with the friction material described in

[18] .

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a friction material composition capable of providing a friction material having excellent shear strength using a material with a low environmental impact, a friction material using the friction material composition, a friction member, and a vehicle.

Brief Description of the Drawings

[0010]

Figure 1

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention (hereinafter also referred to as "the present embodiment") will be described in detail. However, in the following embodiments, the constituent elements are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the present invention. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. Further, the lower limit value and the upper limit value of the numerical range can be arbitrarily combined with the lower limit value and the upper limit value of other numerical ranges, respectively. Furthermore, in this specification, the content of each component in the friction material and the friction material composition means the total content of the plurality of substances present in the friction material and the friction material composition when there are a plurality of substances corresponding to each component, unless otherwise specified.

[0012] [Friction Material Composition] The friction material composition of the present embodiment does not contain copper, or even if it contains copper, the copper content is less than 0.5% by mass as copper element, and contains graphite having a specific surface area of 15 to 100 m 2 / g. In the following description, "graphite having a specific surface area of 15 to 100 m 2 / g" may be referred to as "graphite (I)".

[0013] <Graphite (I)> Graphite (I) is graphite with a specific surface area of 15 to 100 m 2 / g. The friction material formed from the friction material composition of this embodiment contains graphite (I) and thus has excellent shear strength. Generally, since graphite has low affinity with organic components such as binders, when a shear force is applied to a friction material containing graphite, it is considered that the interface between graphite and organic components becomes a starting point and fracture is likely to occur. From this, a method of increasing the specific surface area of graphite leads to an increase in the contact area between graphite and organic components, and it is also considered that the shear strength decreases. In contrast, the inventor of the present invention has found that, unexpectedly, the shear strength is improved by increasing the specific surface area of graphite, and has completed the friction material composition of this embodiment. The reason for the improvement in shear strength by blending graphite with a high specific surface area is not clear, but by increasing the specific surface area of graphite, while the contact area between graphite and organic components increases, the shape of the interface between graphite and organic components becomes complicated. When a shear force is applied, it is expected that the complicated-shaped interface functions like an anti-slip, resulting in an increase in shear strength. In this specification, the specific surface area of graphite is a value determined by the BET method by low-temperature and low-humidity physical adsorption of an inert gas, and specifically, it is a value measured by the method described in the examples.

[0014] From the viewpoint of further achieving both wear resistance and shear strength, the specific surface area of graphite (I) is preferably 15 to 70 m 2 / g, more preferably 15 to 50 m 2 / g. The specific surface area of graphite can be adjusted by, for example, a physical method of carbonizing at a high temperature (for example, 800 to 950 °C) in an atmosphere such as water vapor, carbon dioxide, air, etc.; a chemical method using zinc chloride, potassium hydroxide, etc.; a method of heating and expanding graphite by acid treatment, etc.

[0015] The average particle diameter of graphite (I) is preferably 2 to 200 μm, more preferably 5 to 100 μm, still more preferably 7 to 50 μm, even more preferably 10 to 35 μm, and particularly preferably 12 to 20 μm, from the viewpoint of further enhancing both wear resistance and shear strength. Here, in this specification, the average particle diameter means the value of D 50 (the median diameter of the volume distribution, the cumulative median value) measured using the method of laser diffraction particle size distribution measurement, and the same applies hereinafter. For example, it can be measured with a laser diffraction / scattering type particle size distribution measuring device, trade name: LA-920 (manufactured by Horiba, Ltd.).

[0016] The bulk density of graphite (I) is preferably 0.01 to 0.50 g / cm 3 more preferably 0.02 to 0.40 g / cm 3 still more preferably 0.04 to 0.30 g / cm 3 even more preferably 0.05 to 0.20 g / cm 3 and particularly preferably. The bulk density can be obtained by inserting the sample into a 100 mL glass graduated cylinder without compressing it and dividing the sample weight by the sample volume.

[0017] The ash content of graphite (I) is preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less. The ash content can be measured in accordance with JIS M 8812.

[0018] The content of graphite (I) in the friction material composition of this embodiment is preferably 0.1 to 10% by mass, more preferably 0.5 to 9% by mass, still more preferably 1 to 8% by mass, even more preferably 2 to 7% by mass, and particularly preferably 3 to 6% by mass. When the content of graphite (I) is at least the above lower limit value, the shear strength can be increased while improving the thermal conductivity, and when it is at most the above upper limit value, the friction coefficient can be kept good.

[0019] <Fiber base material> The friction material composition of this embodiment preferably contains a fiber base material. The fiber base material exhibits a reinforcing effect in the friction material. Examples of the fiber base material include organic fibers, inorganic fibers, and metal fibers. The fiber base material may be used alone or in combination of two or more. Here, the organic fiber is a fibrous material mainly composed of an organic substance. In this specification, the "metal fiber" means a fiber composed only of a metal and is not included in the definition of the "inorganic fiber".

[0020] The friction material composition of the present embodiment preferably contains at least one fiber base material selected from the group consisting of organic fibers and inorganic fibers. The content of at least one fiber base material selected from the group consisting of organic fibers and inorganic fibers in the friction material composition of the present embodiment is preferably 2 to 50% by mass, more preferably 4 to 30% by mass, still more preferably 8 to 20% by mass, and particularly preferably 10 to 15% by mass.

[0021] (Organic fiber) Examples of the organic fiber include hemp, cotton, aramid fiber, cellulose fiber, acrylic fiber, phenolic resin fiber (having a crosslinked structure), etc. Among these, aramid fiber is preferable from the viewpoint of heat resistance. The organic fiber may be used alone or in combination of two or more.

[0022] When the friction material composition of the present embodiment contains an organic fiber, its content is preferably 1 to 8% by mass, more preferably 1.5 to 7% by mass, and still more preferably 2 to 5% by mass. When the content of the organic fiber is not less than the above lower limit value, good shear strength, crack resistance, and wear resistance tend to be exhibited. When it is not more than the above upper limit value, deterioration of shear strength and crack resistance due to uneven distribution of the organic fiber and other materials in the friction material composition can be effectively suppressed.

[0023] (Inorganic fiber) The inorganic fiber can exhibit the effect of improving the mechanical strength and wear resistance of the friction material. Examples of the inorganic fibers include glass fibers, mineral fibers, carbon fibers, ceramic fibers, biodegradable ceramic fibers, sepiolite (α-type sepiolite and β-type sepiolite), attapulgite, potassium titanate fibers, silica alumina fibers, flame-resistant fibers, etc. Among these, mineral fibers are preferred from the viewpoint of abrasion resistance. The inorganic fibers may be used alone or in combination of two or more.

[0024] Examples of the mineral fibers include natural mineral fibers and artificial mineral fibers. The mineral fibers may be used alone or in combination of two or more. Examples of the artificial mineral fibers include artificial mineral fibers obtained by melt spinning using blast furnace slag such as slag wool, basalt such as basalt fiber, and other natural rocks as main components. Examples of the artificial mineral fibers also include artificial mineral fibers containing SiO2, Al2O3, CaO, MgO, FeO, Na2O, etc.; artificial mineral fibers containing one or more of these compounds. As the artificial mineral fibers, those containing an aluminum element are preferred, those containing Al2O3 are more preferred, and those containing Al2O3 and SiO2 are even more preferred.

[0025] Mineral fibers are preferably biopersoluble from the perspective of harmfulness to the human body. The biopersoluble mineral fibers referred to here are mineral fibers that have the characteristic of being partially decomposed and discharged outside the body in a short time even when taken into the human body. Specifically, in terms of chemical composition, the total amount of alkali oxides and alkaline earth oxides (the total amount of oxides of sodium, potassium, calcium, magnesium, and barium) is 18% by mass or more, and (a) in the in-vivo durability test by short-term inhalation exposure, the half-life of fibers with a length exceeding 20 μm is less than 10 days, (b) in the in-vivo durability test by short-term intratracheal injection, the half-life of fibers with a length exceeding 20 μm is less than 40 days, (c) there is no significant carcinogenicity in the intraperitoneal administration test, or (d) there are no pathological findings or tumor formations associated with carcinogenicity in the long-term inhalation exposure test. (Refer to Nota Q (exclusion of carcinogenicity application) of EU Directive 97 / 69 / EC). Examples of such biodegradable mineral fibers include mineral fibers containing at least two selected from SiO2, Al2O3, CaO, MgO, FeO, K2O, Na2O, etc. in any combination. Specifically, SiO2 - Al2O3 - CaO - MgO - FeO (-K2O - Na2O) - based fibers can be mentioned.

[0026] When the friction material composition of this embodiment contains mineral fibers as inorganic fibers, the content is preferably 1 to 30% by mass, more preferably 6 to 25% by mass, and even more preferably 8 to 20% by mass in the friction material composition. When the content of the mineral fibers is within the above range, the stability of the friction coefficient, wear resistance, and shear strength will be even more excellent.

[0027] When the friction material composition of this embodiment contains inorganic fibers, the content is preferably 1 to 30% by mass, more preferably 6 to 25% by mass, and even more preferably 8 to 20% by mass. When the content of the inorganic fibers is within the above range, the stability of the friction coefficient, wear resistance, and shear strength will be even more excellent.

[0028] (Metal fiber) Examples of the metal fibers include iron-based fibers, titanium fibers, zinc fibers, aluminum fibers, and the like. When the friction material composition of the present embodiment contains metal fibers, the content thereof is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of suppressing a remarkable increase in the aggressiveness to the disk rotor as the mating material. Further, from the same viewpoint, it is preferable that the friction material composition of the present embodiment does not contain metal fibers.

[0029] When the friction material composition of the present embodiment contains a fiber base material, the content thereof is preferably 0.5 to 50% by mass, more preferably 2 to 40% by mass, even more preferably 4 to 30% by mass, still more preferably 8 to 20% by mass, and particularly preferably 10 to 15% by mass.

[0030] The friction material composition of the present embodiment preferably further contains at least one selected from the group consisting of a binder, an organic filler, and an inorganic filler.

[0031] <Binder> The binder has a function of binding and integrating the respective components contained in the friction material composition to give a predetermined shape and strength. The binder may be used alone or in combination of two or more. There is no particular limitation on the binder contained in the friction material composition, but a thermosetting resin generally used as the binder of the friction material can be used. Examples of the thermosetting resin include phenol resins, modified phenol resins, elastomer-dispersed phenol resins, epoxy resins, polyimide resins, melamine resins, and the like. Here, examples of the modified phenol resin include acrylic-modified phenol resins, silicone-modified phenol resins, cashew-modified phenol resins, epoxy-modified phenol resins, alkylbenzene-modified phenol resins, and the like. Examples of the elastomer-dispersed phenol resin include acrylic elastomer-dispersed phenol resins, silicone elastomer-dispersed phenol resins, and the like. In particular, phenolic resins, acrylic-modified phenolic resins, silicone-modified phenolic resins, and alkylbenzene-modified phenolic resins are preferred because they impart good heat resistance, moldability, and coefficient of friction, and phenolic resins are more preferred. The thermosetting resin may be used alone or in combination of two or more.

[0032] When the friction material composition of the present embodiment contains a binder, its content is preferably 5 to 25% by mass, more preferably 6 to 20% by mass, still more preferably 7 to 15% by mass, and particularly preferably 8 to 12% by mass. When the content of the binder is within the above range, the balance of the strength, good coefficient of friction, wear resistance, etc. of the friction material tends to be further improved.

[0033] <Organic filler> The organic filler can exhibit a function as a friction modifier for improving vibration damping properties, wear resistance, etc. Here, in the present embodiment, the definition of the organic filler does not include fibrous ones (for example, organic fibers described later). The organic filler may be used alone or in combination of two or more.

[0034] As the organic filler, organic fillers generally used in friction material compositions can be used. Examples of the organic filler include cashew particles, rubber, and melamine particles. Among these, cashew particles and rubber are preferred from the viewpoints of improving the stability of the coefficient of friction and wear resistance and suppressing squeal. Cashew particles and rubber may be used in combination, or those in which cashew particles are coated with rubber may be used.

[0035] The cashew particles are obtained by pulverizing a cured product of cashew nut shell oil and are sometimes referred to as cashew dust. Cashew superparticles are generally classified into tea-based, tea-black-based, black-based, etc. according to the type of curing agent used in the curing reaction. By adjusting the molecular weight, etc., it is possible to easily control the heat resistance, sound vibration properties, and film-forming properties on the disk rotor, which is the friction object. As the cashew superparticles, commercially available products can be used. When the friction material composition of the present embodiment contains cashew superparticles, the content is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 7% by mass. When the total content of the cashew superparticles is equal to or higher than the above lower limit value, the sound vibration properties tend to be improved, and when it is equal to or lower than the above upper limit value, the decrease in heat resistance and crack resistance tends to be suppressed.

[0036] Examples of the rubber include rubbers commonly used in friction material compositions, such as natural rubber and synthetic rubber. Examples of the synthetic rubber include acrylonitrile-butadiene rubber (NBR), acrylic rubber, isoprene rubber, polybutadiene rubber (BR), styrene-butadiene rubber (SBR), silicone rubber, and pulverized powder of tire tread rubber. Among these, from the viewpoint of the balance of heat resistance, flexibility, and manufacturing cost, acrylonitrile-butadiene rubber (NBR) and pulverized powder of tire tread rubber are preferred.

[0037] When the friction material composition of the present embodiment contains rubber, the content is preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass, and even more preferably 1.5 to 5% by mass. When the rubber content is within the above range, the elastic modulus of the friction material tends to increase, and the vibration damping properties such as squeal tend not to deteriorate, and the deterioration of heat resistance and the strength reduction due to heat history tend not to occur.

[0038] When the friction material composition of the present embodiment contains an organic filler, the total content is preferably 2 to 20% by mass, more preferably 3 to 15% by mass, and even more preferably 5 to 10% by mass from the viewpoint of achieving a good balance between the above effects due to the addition of the organic filler and the effects of other components.

[0039] <Inorganic filler> The friction material composition of the present embodiment preferably further contains an inorganic filler. The inorganic filler can exhibit a function as a friction modifier for avoiding deterioration such as heat resistance, abrasion resistance, and stability of the friction coefficient. Here, in the present embodiment, the definition of the inorganic filler does not include fibrous materials (for example, the aforementioned inorganic fibers) and graphite. The inorganic filler may be used alone or in combination of two or more.

[0040] Examples of the inorganic filler include metal sulfides such as antimony trisulfide, tin sulfide, molybdenum disulfide, bismuth sulfide, and zinc sulfide; titanates such as potassium titanate, lithium potassium titanate, sodium titanate, and magnesium potassium titanate; mica, coke, calcium hydroxide, calcium oxide, sodium carbonate, calcium carbonate, magnesium carbonate, barium sulfate, dolomite, vermiculite, calcium sulfate, talc, clay, zeolite, chromite, zirconium oxide, titanium oxide, magnesium oxide, iron trioxide, zinc oxide, γ-alumina, etc.; metal powders such as iron powder, cast iron powder, aluminum powder, nickel powder, tin powder, zinc powder, and alloy powders containing at least one of the above metals. The shape of the inorganic filler is not particularly limited and may be granular, plate-like, etc. Examples of the granular one include granular potassium titanate, and examples of the plate-like one include plate-like potassium titanate.

[0041] When the friction material composition of the present embodiment contains alumina, its content is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, and still more preferably 0.5 to 3% by mass. When the content of alumina is within the above range, it tends to be easy to impart appropriate grindability.

[0042] When the friction material composition of the present embodiment contains a titanate, its content is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. When the content of the titanate is at least the above lower limit value, the stability of the friction coefficient tends to be improved and the wear resistance tends to be good. When it is at most the above upper limit value, a decrease in the mechanical strength and a decrease in the wear resistance of the friction material are suppressed.

[0043] When the friction material composition of the present embodiment contains zirconium oxide, its content is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. When the content of zirconium oxide is within the above range, it tends to be easy to impart appropriate grindability.

[0044] When the friction material composition of the present embodiment contains a metal sulfide, the content of the metal sulfide is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 7% by mass. When the content of the metal sulfide is within the above range, excellent stability of the friction coefficient can be obtained.

[0045] When the friction material composition of the present embodiment contains mica, the content of mica is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 7% by mass. When the content of mica is within the above range, it tends to be easy to impart appropriate grindability.

[0046] When the friction material composition of the present embodiment contains calcium hydroxide, its content is preferably 1 to 15% by mass, more preferably 1 to 10% by mass, and even more preferably 3 to 8% by mass. When the content of calcium hydroxide is within the above range, it tends to be easy to impart appropriate grindability.

[0047] When the friction material composition of the present embodiment contains barium sulfate, its content is preferably 1 to 40% by mass, more preferably 5 to 20% by mass, and even more preferably 10 to 15% by mass. Note that barium sulfate serves as a filler for adjusting the volume of the friction material composition. That is, the content of barium sulfate depends on the content of other components, and the balance can be supplemented with barium sulfate to make the friction material composition a predetermined amount. By containing barium sulfate, the bulk density of the friction material composition increases, and the handleability becomes good.

[0048] The friction material composition of the present embodiment may or may not contain metal powder. When it contains metal powder, its content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less. Also, the content of metal powder in the friction material composition of the present embodiment may be 1% by mass or more.

[0049] When the friction material composition of the present embodiment contains an inorganic filler, the total content of the inorganic filler is preferably 40 to 85% by mass, more preferably 50 to 80% by mass, and even more preferably 60 to 75% by mass, from the viewpoint of achieving a good balance between the above effects due to the addition of the inorganic filler and the effects of other components.

[0050] (Other materials) The friction material composition of the present embodiment may or may not contain other materials as needed in addition to the above-mentioned materials. Examples of other materials include organic additives such as fluorine-based polymers such as polytetrafluoroethylene (PTFE) from the viewpoint of improving wear resistance and thermal fade characteristics. When the friction material composition of the present embodiment contains the above-mentioned other materials, its content is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less.

[0051] (Copper content) The friction material composition of the present embodiment preferably does not contain copper. When it contains copper, by setting the copper content in the friction material composition to less than 0.5% by mass as copper element, even if it is released into the environment as wear powder, it can be made not to cause pollution of rivers and the like. The above copper content indicates the content of copper element (Cu) contained in fibrous, powdery copper, copper alloy and copper compound in the friction material composition of the present embodiment in the whole friction material composition. In the friction material composition of the present embodiment, the copper content is more preferably 0.2% by mass or less, and even more preferably 0.05% by mass or less as copper element.

[0052] (Iron content) In the friction material composition of the present embodiment, from the viewpoint of avoiding durability reduction due to rusting, etc., it is preferable not to contain iron-based metal. However, even when it contains iron-based metal, by setting the content of iron-based metal in the friction material composition to less than 0.5% by mass as iron element, the rust resistance can be made good. In the friction material composition of the present embodiment, the content of iron-based metal is more preferably 0.2% by mass or less, and even more preferably 0.05% by mass or less as iron element. Here, the iron-based metal is a metal mainly composed of iron, and refers to general steel. The above iron-based metal content indicates the content of iron element (Fe) contained in iron, iron alloy and iron compound in the friction material composition of the present embodiment in the whole friction material composition.

[0053] (Asbestos content) The friction material composition of the present embodiment is classified as an NAO (Non-Asbestos-Organic) material, and is a so-called non-asbestos friction material composition (a friction material composition that does not contain asbestos, or a friction material composition that contains asbestos but the asbestos content is extremely small). In the friction material composition of the present embodiment, from the viewpoint of harmfulness, it is preferable not to contain asbestos. However, even when it contains asbestos, the asbestos content in the friction material composition of the present embodiment is preferably 0.2% by mass or less.

[0054] [Friction material] The friction material of this embodiment is a friction material containing the friction material composition of this embodiment. The friction material of this embodiment may be formed only from the friction material composition of this embodiment, or may be a friction material having an upper layer material and a lower layer material, and at least one of the upper layer material and the lower layer material is formed from the friction material composition of this embodiment. When the friction material has an upper layer material and a lower layer material, the friction material composition of this embodiment is preferably used for the upper layer material. Referring to FIG. 1, the friction material having an upper layer material and a lower layer material will be described. The friction material composition of this embodiment is preferably used as the upper layer material 1 of the friction member in order to exhibit the stability of the friction coefficient during normal load braking. The upper layer material 1 is a friction material that becomes the friction surface of the friction member, and the lower layer material 2 is a layer for improving the shear strength and crack resistance in the vicinity of the adhesive portion between the friction material and the backing metal, which is interposed between the upper layer material 1 and the backing metal 3.

[0055] The friction material can preferably be manufactured by molding the friction material composition by hot pressing. The friction material having an upper layer material and a lower layer material is prepared by separately mixing the friction material composition for the upper layer material and the friction material composition for the lower layer material using a mixer such as a Lodige mixer (Lodige is a registered trademark), a kneader, or an Ehrlich mixer (Ehrlich is a registered trademark), and integrally preforming the mixture for the upper layer material and the mixture for the lower layer material in a molding die. Then, the obtained preform is molded for 2 to 10 minutes under conditions such as a molding temperature of 130 to 160°C and a molding pressure of 20 to 50 MPa, and the obtained molded product is heat-treated at 150 to 250°C for 2 to 10 hours. Also, if necessary, painting, scorch treatment, polishing treatment, etc. may be performed. Among the above steps, the preforming step may be omitted and the mixture may be directly hot-molded.

[0056] The friction material can be used as a friction material for disk brake pads of automobiles and the like, and a friction material for drum brake linings of automobiles and the like. Further, by performing steps such as molding, processing, and attaching the friction material composition into a target shape, it can also be used as a friction material for clutch facings, electromagnetic brakes, holding brakes, and the like. Since the friction material of this embodiment is excellent in the stability of the friction coefficient during normal load braking, it is suitable as a friction material for vehicle use, particularly for automobiles.

[0057] [Friction member] The friction member of this embodiment is a friction member having a friction material and a back metal, wherein the friction material does not contain copper, or even if it contains copper, the copper content is less than 0.5% by mass as copper element, and the specific surface area is 15 to 100 m 2 / g and contains graphite, and is a friction member. The description of each component contained in the friction material of the friction member of this embodiment is the same as the description of the components contained in the friction material composition of the above-described embodiment of this invention, except for the chemical state change such as the curable resin. For example, the content of each component in the friction material composition can be read as the content of each component in the friction material.

[0058] The back metal is used for the friction member in order to improve the mechanical strength of the friction member. Examples of the material of the back metal include metals such as iron and stainless steel; fiber reinforced plastics such as inorganic fiber reinforced plastics and carbon fiber reinforced plastics. The friction member of this embodiment may further have a primer layer for the purpose of surface modification to enhance the adhesion effect of the back metal and / or an adhesive layer for the purpose of adhesion between the back metal and the friction material between the back metal and the friction material. As the primer layer and the adhesive layer, those usually used for friction members such as brake pads and brake linings may be used.

[0059] In this embodiment, for the friction member 6 in FIG. 1, in the back metal 3, a friction member having a shim 4 on the side opposite to the side having the backing material 2 can also be provided. The shim 4 is generally a spacer used to improve the vibration damping property of the friction member.

[0060] [Vehicle] This embodiment also provides a vehicle equipped with the friction material or friction member of this embodiment. More specifically, a vehicle equipped with the friction material or friction member of this embodiment as a friction member such as a brake pad or a brake lining is also provided. Examples of the vehicle include an automobile and a motorcycle.

Example

[0061] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples.

[0062] [Measurement of Specific Surface Area of Graphite] The specific surface area of graphite was measured in accordance with the BET method (JIS Z 8830, single-point method) by nitrogen adsorption.

[0063] For each friction material obtained in the examples and comparative examples, measurement and evaluation were performed according to the following methods. [Measurement and Evaluation Methods] (1) Shear Strength of Friction Material In accordance with JIS D4422 (2007), the shear strength at room temperature (25 °C) was measured. (2) Abrasion Resistance of Friction Material In accordance with JASO C427, the wear amount of the friction material at a pre-brake temperature of 300 °C was measured.

[0064] [Manufacture of Disc Brake Pad] In manufacturing the disc brake pad, the components of the following friction material composition were prepared. Each component described in Table 1 is as follows. (Binder) · Resin A: Silicon-modified phenolic resin · Resin B: Acrylic-modified phenolic resin (Organic filler) · Cashew super particle · Rubber component: Tire rubber powder (Fiber substrate) · Aramid fiber · Mineral fiber A: Rock wool · Mineral fiber B: Ceramic fiber (Graphite) · Graphite 1: Specific surface area 15 - 25 m 2 / g, average particle diameter 16 μm · Graphite 2: Specific surface area 25 - 50 m 2 / g, average particle diameter 31 μm · Graphite 3: Specific surface area 50 - 100 m 2 / g, average particle diameter 3 μm · Graphite 4: Specific surface area less than 15 m 2 / g, average particle diameter 25 μm (Inorganic filler) · Alumina · Titanate · Zirconium oxide · Antimony trisulfide · Tin sulfide · Mica · Calcium hydroxide · Barium sulfate

[0065] [Examples 1 - 6, Comparative Examples 1 - 2] (Manufacture of disc brake pads) Each component was blended according to the blending amounts shown in Table 1 to obtain each friction material composition. This friction material composition was mixed with a Lodige mixer (manufactured by Matsubo Co., Ltd., trade name: Lodige mixer M20) to obtain a mixture. The obtained mixture was integrally preformed with a molding press (manufactured by Oji Seiko Co., Ltd.). The obtained preform was heated and pressure - molded together with an iron back plate (manufactured by Hitachi Automotive Systems, Ltd.) using a molding press (manufactured by Oji Seiko Co., Ltd.) under the conditions of a molding temperature of 145 °C, a molding pressure of 35 MPa, and a molding time of 5 minutes. The obtained molded product was heat - treated at 200 °C for 4.5 hours, polished using a rotary polisher, and subjected to a scorch treatment at 500 °C to obtain a disc brake pad. Note that the disc brake pads obtained in the examples and comparative examples have a friction material thickness of 9.5 mm. From the obtained disk brake pads, test pieces with a size of 20 mm × 45 mm square were produced using a cutting machine, and each measurement and evaluation were carried out according to the above method. The results are shown in Table 1.

[0066]

Table 1

[0067] From Table 1, the friction materials of this embodiment of Examples 1 to 6 were excellent in shear strength and wear resistance. On the other hand, the friction materials of Comparative Examples 1 and 2 using graphite with a specific surface area of less than 15 m 2 / g were particularly inferior in shear strength.

Industrial Applicability

[0068] The friction member and friction material of the present invention are friction materials that do not contain copper or contain a small amount of copper, have a low environmental load, and are excellent in the shear strength and wear resistance of the friction material. Therefore, they are particularly suitable as friction members and friction materials for vehicles and the like.

Explanation of Reference Numerals

[0069] 1 Upper sheet 2 Lower sheet 3 Backing plate 4 Shim 5 Friction material 6 Friction member

Claims

Claim 1 A friction member having a friction material and a backing plate, The friction material contains no copper or, even if it contains copper, the copper content is less than 0.5% by mass as elemental copper, and has a specific surface area of 15 to 50 m ２ / g, and contains graphite and inorganic fibers, the average particle diameter of the graphite being 7 to 50 μm, and the inorganic fibers containing 6 to 25% by mass of mineral fibers, a friction member. Claim 2 The friction member according to claim 1, wherein the friction material contains 0.1 to 10% by mass of the graphite. Claim 3 The friction member according to claim 1 or 2, wherein the friction material further contains organic fibers. Claim 4 The friction member according to claim 3, wherein the friction material contains 8 to 30% by mass of the inorganic fibers and the organic fibers. Claim 5 The friction member according to any one of claims 1 to 4, wherein the friction material further contains one or more selected from the group consisting of a binder, an organic filler, and an inorganic filler. Claim 6 The friction member according to any one of claims 1 to 5, which is for a disk brake pad or a drum brake lining. Claim 7 A vehicle equipped with the friction member according to any one of claims 1 to 6. Claim 8 Either does not contain copper or, even if it contains copper, the copper content is less than 0.5% by mass as elemental copper, and the specific surface area is 15 to 50 m ２ / g, and contains graphite and inorganic fibers, wherein the average particle diameter of the graphite is 7 to 50 μm, and the inorganic fibers contain 6 to 25% by mass of mineral fibers, a friction material composition. Claim 9 The friction material composition according to claim 8, which contains 0.1 to 10% by mass of the graphite. Claim 10 The friction material composition according to claim 8 or 9, which further contains organic fibers. Claim 11 The friction material composition according to claim 10, which contains 8 to 30% by mass of the inorganic fibers and the organic fibers. Claim 12 The friction material composition according to any one of claims 8 to 11, which further contains one or more selected from the group consisting of a binder, an organic filler, and an inorganic filler. Claim 13 The friction material composition according to any one of claims 8 to 12, which is for a disk brake pad or a drum brake lining. Claim 14 A friction material comprising the friction material composition according to any one of claims 8 to 13. Claim 15 A vehicle equipped with the friction material according to claim 14.

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