JP2017002185A - Friction material composition, friction material and friction member using friction material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material composition providing a friction material containing no copper as an element or with content of no more than 0.5 mass%, forming TF suitably even under low load braking represented by a regenerative cooperative brake with a composition low in environmental harmfulness and human body harmfulness and exhibiting stable friction coefficient.SOLUTION: There is provided a friction material composition containing a binder, an organic filler, an inorganic filler and a fiber substrate, no copper as an element or with content of the copper of no more than 0.5 mass%, cashew dust of 1 to 10 mass%, potassium titanate and further at least one kind of lithium potassium titanate and magnesium potassium titanate and at least one kind of zirconium silicate, zirconium oxide and magnesium oxide of 11 to 30 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a friction material composition suitable for friction materials such as disc brake pads and brake linings used in braking of automobiles, etc., a friction material using the friction material composition, and a friction member, and in particular, asbestos. The present invention relates to a so-called non-asbestos friction material.

  In automobiles and the like, friction materials such as disc brake pads and brake linings are used for braking. Friction materials such as a disc brake pad and a brake lining play a role of braking by friction with a disc rotor, a brake drum, or the like as a counterpart material. For this reason, friction materials not only require an appropriate coefficient of friction (effect characteristics) depending on the conditions of use, but also make brake noise less likely to occur (squeal characteristics) and have a longer life of friction material (wear resistance). Etc. are required.

  The friction material is roughly classified into a semi-metallic material containing 30 to 60% by mass of steel fibers as a fiber base material, a low steel material containing less than 30% by mass of steel fibers, and an NAO material containing no steel fibers. However, a friction material containing a small amount of steel fiber may be classified as a NAO material.

  Since NAOO material does not contain steel fibers or has a very low content of steel fibers, it has a feature that it is less aggressive against a disk rotor as a counterpart material than semi-metallic materials or low steel materials. Because of these advantages, NAO materials that are effective, squealed, and wear-resistant in Japan and the United States are currently mainstream. In Europe, low steel materials were often used from the viewpoint of maintaining the friction coefficient during high-speed braking, but recently, NAO materials are less likely to cause tire wheel dirt and brake noise in order to respond to a higher-grade market. Is increasingly being used.

  The NAO material generally contains copper in a powder or fiber state. However, the friction material containing copper or a copper alloy contains copper in the wear powder generated at the time of braking, and therefore it is suggested that the friction material may contaminate rivers and lakes. Since then, a bill has been passed to prohibit the sale of friction materials containing more than 5% by weight of copper, and after 2023 more than 0.5% by weight of copper, and to assemble them into new cars. There is an urgent need to develop NAO materials that do not contain or have a low copper content.

  In such a movement, several patents (Patent Documents 1, 2, etc.) have been proposed for friction materials that do not contain copper or have a low copper content.

JP 2002-138273 A Japanese Patent Laying-Open No. 2015-004037

  The NAO material forms a transfer film (TF) in which the friction material composition is transferred to the surface of the disk rotor. This TF contributes to stabilization of the friction coefficient and also to suppression of wear. For this reason, the formation of an appropriate amount of TF is extremely important in expressing the function of the NAO material.

  Examples of the components in the friction material forming TF include various organic substances and titanates. The phenol resin, rubber component, and organic matter such as cashew dust form a liquid decomposition product by heat generated during braking and form TF on the surface of the disk rotor. In addition, titanates represented by potassium titanate, lithium potassium titanate, and magnesium potassium titanate extend to the friction interface by braking and become a component of TF.

  In addition, copper is also mentioned as an important component in the friction material constituting TF. Copper is used as a friction material in the form of powder or fiber, but has high ductility and malleability, and extends to the friction material surface and the disk rotor surface by braking to form TF. Further, by crushing or filling in the polishing grooves remaining on the brake rotor surface at the time of a new article, there is an effect of forming a surface on which the above-mentioned organic decomposition products, titanates and the like are easily fixed as TF. However, a friction material that does not contain copper or has a low copper content does not have such an action and TF is difficult to be formed.

  Furthermore, in recent years, regenerative cooperative brakes have become popular in the automobile market. In the regenerative cooperative brake, not only the frictional resistance by the friction material as usual but also the resistance at the time of converting the rotational force of the tire into electric power is used as the braking force. In automobiles using such regenerative cooperative brakes, regenerative cooperative brakes are frequently used for braking in high-speed driving conditions because the tire's rotational force is high and power generation efficiency is increased. This is limited to a low-speed traveling state in which the power generation efficiency of the brake is low, and the ratio of braking by the friction material is significantly reduced.

  For this reason, in an automobile using a regenerative cooperative brake, the amount of heat generated at the friction interface during braking by the friction material is small, so that TF components such as organic decomposition products and titanates are difficult to transfer to the disk rotor surface. Moreover, since copper can no longer be used for the above reasons, it becomes even more difficult to form TF and to exhibit stable friction characteristics.

  In particular, since the braking is electronically controlled in the regenerative cooperative brake, a braking force exceeding the driver's assumption that the friction coefficient of the friction material is not stable may occur, resulting in a sudden braking. Conversely, the braking force required by the driver cannot be obtained and the braking distance may be extended, so that comfortable driving is impaired.

  From this point of view, Patent Documents 1 and 2 focus on the high thermal conductivity and high-temperature lubricity of copper and complement the friction characteristics during high-load braking during high-speed running. Low load braking from low speed running is not considered. For example, in Patent Document 1, in order to supplement heat conduction, magnesium oxide and graphite are contained in the friction material in an amount of 45 to 80% by volume instead of copper, and the ratio of magnesium oxide and graphite is 1/1 to 4/1. However, it is difficult to improve various friction characteristics in a well-balanced manner because the amount of magnesium oxide as an abrasive and the amount of graphite as a lubricant are extremely increased.

  Moreover, in patent document 2, while complementing high temperature lubricity, 1-15 mass% of ferrous sulfide is contained instead of copper, and flaky graphite with an average particle diameter of 1-100 micrometers is 0.3-5. Although a method for improving the friction coefficient and wear resistance during high-speed and high-load braking has been proposed by containing the mass%, it is difficult to improve the stability of the friction coefficient during light-load braking.

  Therefore, the present invention has a composition that does not contain copper as an element or has a low environmental hazard that does not exceed 0.5 mass%, and a low human hazard, and is a light load braking represented by a regenerative cooperative brake. However, an object of the present invention is to provide a friction material composition that appropriately forms TF and gives a friction material that exhibits a stable coefficient of friction. It is another object of the present invention to provide a friction material and a friction member using the friction material composition.

  The present inventors pay attention to cashew dust and titanate, and by setting the amount of cashew dust and the type and amount of titanate to an appropriate range, it is possible to form an appropriate amount of TF even with light load braking. I found it. Moreover, it discovered that the friction material which expresses the stable friction coefficient could be provided by using a specific grinding material together by specific amount. The friction material composition of the present invention is made from these findings, and specifically, is a friction material composition containing a binder, an organic filler, an inorganic filler, and a fiber substrate, and as an element The copper content does not exceed 0.5% by mass, the cashew dust is contained 1 to 10% by mass, the potassium titanate is contained, and further, lithium potassium titanate and magnesium potassium titanate It contains at least one of them, and contains 11 to 30% by mass of at least one of zirconium silicate, zirconium oxide and magnesium oxide.

  In the friction material composition of the present invention, the total content of potassium titanate, lithium potassium titanate and magnesium potassium titanate is preferably 10 to 35% by mass. Moreover, it is preferable to contain 0.5-5 mass% of at least 1 sort (s) among iron, tin, zinc, and aluminum as metal powder or metal fiber.

  The friction member of the present invention is formed by molding the friction material composition described above, and the friction member of the present invention integrates the friction material formed by molding the friction material composition and a back metal. It will be.

  According to the present invention, a light load braking represented by a regenerative cooperative brake or the like while having a composition having low environmental hazard and human injury when used in a friction material such as an automobile disc brake pad or brake lining. It is possible to provide a friction material composition that provides a friction material that sometimes forms a stable TF and develops a stable coefficient of friction. Moreover, according to this invention, the friction material and friction member which have the said characteristic can be provided.

  Hereinafter, the friction material composition of the present invention, the friction material using the same, and the friction member will be described in detail. The friction material composition of the present invention is a so-called non-asbestos friction material composition that does not contain asbestos and does not contain asbestos.

[Friction material composition]
The friction material composition of this embodiment is a friction material composition containing a binder, an organic filler, an inorganic filler, and a fiber base material, and does not contain copper as an element or has a copper content of 0. Not exceeding 5 mass%, containing 1 to 10 mass% of cashew dust, containing potassium titanate, and further containing at least one of lithium potassium titanate and magnesium potassium titanate, zirconium silicate, zirconium oxide And containing at least one of magnesium oxide in an amount of 11 to 30% by mass. In addition, said "copper as an element" shows the content rate in the total friction material composition of the copper element contained in copper, copper alloy, and a copper compound, such as fibrous form and a powder form.
* Since the friction material composition of the present invention is defined as a non-asbestos friction material composition in the previous stage, it is simply referred to as “friction material composition” hereinafter.

[Cashew dust (organic filler)]
The friction material composition of the present invention contains cashew dust as an organic filler. The organic filler is included as a friction modifier for improving the sound vibration performance and wear resistance of the friction material. Since cashew dust decomposes at a low temperature, TF can be formed on the disk rotor surface as a liquid decomposition product even during light load braking. The cashew dust is not particularly limited as long as it is obtained by pulverizing a cashew nut shell oil that has been polymerized and cured, and is usually used for a friction material. The cashew dust content is preferably 1 to 10% by mass, more preferably 1 to 8% by mass, and even more preferably 2 to 7% by mass. By setting the content of cashew dust to 1 to 10% by mass, it is possible to avoid deterioration in sound vibration performance such as squealing due to an increase in the elastic modulus of the friction material, deterioration in heat resistance, strength due to thermal history. Degradation can be avoided.

[Other organic fillers]
In the friction material composition of the present invention, in addition to the above cashew dust, a rubber component may be used as the organic filler. Examples of the rubber component include tire rubber, acrylic rubber, isoprene rubber, NBR (nitrile butadiene rubber), SBR (styrene butadiene rubber) and the like, and these can be used alone or in combination of two or more. In addition, when cashew dust and a rubber component are used in combination, cashew dust coated with a rubber component may be used, but from the viewpoint of sound vibration performance, the cashew dust and the rubber component may be separately provided. .

  The content of the organic filler in the friction material composition of the present invention is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, and 2 to 10% by mass. Further preferred. By setting the content of the organic filler in the range of 1 to 20% by mass, it is possible to avoid deterioration of sound vibration performance such as squeal due to an increase in the elastic modulus of the friction material, deterioration of heat resistance, heat It is possible to avoid a decrease in strength due to history.

[Binder]
The friction material composition of the present invention contains a binder. The binding material provides strength by integrating the organic filler and the fiber base material included in the friction material composition. As the binder contained in the friction material composition of the present embodiment, a thermosetting resin usually used for a friction material can be used. Examples of the thermosetting resin include various modified phenol resins such as phenol resin, acrylic rubber modified phenol resin, silicone rubber modified phenol resin, cashew modified phenol resin, epoxy modified phenol resin, and alkylbenzene modified phenol resin. It can be used alone or in combination of two or more. In order to provide good heat resistance, moldability and friction coefficient, it is preferable to use a phenol resin, an acrylic rubber-modified phenol resin, a silicone rubber-modified phenol resin, or an alkylbenzene-modified phenol resin.

  The content of the binder in the friction material composition of the present invention is preferably 5 to 20% by mass, more preferably 5 to 15% by mass, and further preferably 5 to 10% by mass. . By setting the content of the binder in the range of 5 to 20% by mass, it is possible to further suppress the strength reduction of the friction material, reduce the porosity of the friction material, and increase the elastic modulus. Vibration performance deterioration can be suppressed.

[Titanate (inorganic filler)]
The friction material composition of the present invention contains an inorganic filler. The inorganic filler is included as a friction modifier in order to avoid deterioration of the heat resistance of the friction material. In the friction material composition of the present invention, the inorganic filler contains titanate. As described above, the titanate extends to the friction interface by braking and has an effect of becoming a component of TF.

  The total content of the titanate is preferably 10 to 35% by mass, more preferably 10 to 30% by mass, and still more preferably 13 to 25% by mass. By setting the content of titanate to 10% by mass or more, the stability of the friction coefficient is improved, and by setting the content to 35% by mass or less, an extreme increase in porosity can be avoided. If the porosity is extremely increased, not only the mechanical strength of the friction material is reduced, but also the stability of the friction coefficient is reduced due to moisture absorption, and the risk that the friction material and the counterpart are fixed by rust increases. Further, as the titanate, 8 potassium titanate, 6 potassium titanate, lithium potassium titanate, magnesium potassium titanate, or the like can be used. However, when only potassium titanate is contained, deterioration of wear resistance may be a problem, and conversely, when only lithium potassium titanate or magnesium potassium titanate is contained, the friction coefficient is extremely lowered. May be a problem. Therefore, it is essential to contain not only potassium titanate but also at least one of lithium potassium titanate and magnesium potassium titanate. In addition, the titanate that can be used in the friction material composition of the present embodiment is not subject to restrictions on particle size, shape, and the like as long as extreme characteristics are not deteriorated. For example, there is no problem even if the shape is a needle shape, a plate shape, a granular shape, an amoeba shape, or the like.

[Zirconium silicate, zirconium oxide, and magnesium oxide (inorganic filler)]
The friction material composition of the present invention contains at least one of zirconium silicate, zirconium oxide, and magnesium oxide in addition to the titanate as an inorganic filler. Zirconium silicate, zirconium oxide, and magnesium oxide act as abrasives, and by making the total content of zirconium silicate, zirconium oxide, and magnesium oxide 11 mass% or more, the aggressiveness to the disk rotor that is the counterpart material Is appropriately applied, and a polishing groove in manufacturing remaining on the surface of the brake rotor at the time of a new article is polished, so that a surface on which TF can be easily fixed can be formed. On the other hand, if the contents of zirconium silicate, zirconium oxide, and magnesium oxide are excessive, the aggressiveness to the disk rotor, which is the counterpart material, becomes excessive and causes wear of the disk rotor, and the strength of the friction material decreases significantly. Then, the abrasive that has fallen off during friction acts as an abrasive powder, and the amount of wear of the friction material increases. For this reason, these problems are solved by setting the content of zirconium silicate, zirconium oxide, and magnesium oxide to 30% by mass or less. In addition, although content of zirconium silicate, a zirconium oxide, and magnesium oxide shall be 11-30 mass% in total as above-mentioned, it is more preferable that it is 11-25 mass%, and is 11-22 mass%. More preferably.

  The median diameter of the above-mentioned zirconium silicate, zirconium oxide, and magnesium oxide is preferably 0.5 to 30 μm, more preferably 0.5 to 20 μm, and further preferably 0.5 to 15 μm. . When the median diameter of zirconium silicate, zirconium oxide, and magnesium oxide is 0.5 μm or more, a good friction coefficient and aggressiveness to the disk rotor are expressed, and when it is 30 μm or less, the dispersibility at the friction interface is increased. In addition to stabilizing the friction coefficient, it is possible to avoid an extremely high attack on the mating material.

  The median diameter of the zirconium silicate, zirconium oxide, and magnesium oxide can be measured using a method such as laser diffraction particle size distribution measurement. For example, it can be measured with a laser diffraction / scattering particle size distribution measuring device, trade name: LA.920 (manufactured by Horiba, Ltd.). Moreover, as long as the effects of the present invention are not impaired, the titanate, zirconium silicate, zirconium oxide, and magnesium oxide of this embodiment can be used in combination with inorganic fillers that are usually used for friction materials. .

[Other inorganic fillers]
Examples of the inorganic filler other than the titanate, zirconium silicate, zirconium oxide, and magnesium oxide include, for example, tin sulfide, molybdenum disulfide, iron sulfide, bismuth sulfide, zinc sulfide, calcium hydroxide, calcium oxide, sodium carbonate. , Calcium carbonate, magnesium carbonate, barium sulfate, dolomite, coke, graphite, mica, iron oxide, vermiculite, calcium sulfate, talc, clay, zeolite, zirconium silicate, mullite, chromite, titanium oxide, silica, γ-alumina, etc. Alumina can be used, and these can be used alone or in combination of two or more.

  The total content of the inorganic filler, including titanate, zirconium silicate, zirconium oxide, and magnesium oxide, is preferably 20 to 80% by mass, and 30 to 80% by mass in the friction material composition. Is more preferably 40 to 80% by mass. When content of an inorganic filler shall be 20-80 mass%, a heat resistant deterioration can be avoided.

[Fiber base]
The friction material composition of the present invention contains a fiber base material. The fiber base material exhibits a reinforcing action in the friction material. Examples of the fiber base material include organic fibers, inorganic fibers, and metal fibers.

  In the friction material composition of the present invention, an aramid fiber, an acrylic fiber, a cellulose fiber, a phenol resin fiber, or the like can be used as an organic fiber, and these can be used alone or in combination of two or more. Among these, it is preferable to use an aramid fiber from the viewpoint of heat resistance and a reinforcing effect.

  As the inorganic fiber, wollastonite, ceramic fiber, biodegradable ceramic fiber, mineral fiber, carbon fiber, glass fiber, potassium titanate fiber, aluminosilicate fiber, etc. can be used, one or a combination of two or more types However, from the viewpoint of harm to the human body, it is preferable not to contain attractive potassium titanate fibers or the like.

The mineral fiber referred to here is a man-made inorganic fiber melt-spun mainly composed of blast furnace slag such as slag wool, basalt such as basalt fiber, and other natural rocks, and is a natural mineral containing Al element. Is more preferable. Specifically, those containing SiO ₂ , Al ₂ O ₃ , CaO, MgO, FeO, Na ₂ O, etc., or those containing one or more of these compounds can be used as mineral fibers. Of these, those containing an Al element are more preferred. Since the adhesive strength with each component in the friction composition tends to decrease as the average fiber length of the entire mineral fiber contained in the friction material composition increases, the average fiber length of the entire mineral fiber is preferably 500 μm or less, More preferably, it is 100-400 micrometers. Here, the average fiber length refers to a number average fiber length indicating an average value of the lengths of all corresponding fibers. For example, the average fiber length of 200 μm indicates that 50 mineral fibers used as a friction material composition raw material are randomly selected, the fiber length is measured with an optical microscope, and the average value is 200 μm.

The mineral fiber used in the present invention is preferably biosoluble from the viewpoint of human harm. The term “biosoluble mineral fiber” as used herein refers to a mineral fiber having a characteristic that even if it is taken into the human body, it is partially decomposed and discharged outside the body in a short time. Specifically, the chemical composition is alkali oxide, alkaline earth oxide total amount (total amount of oxides of sodium, potassium, calcium, magnesium, barium) is 18% by mass or more, and in a short-term biopermanent test by respiration, A fiber with a mass half-life of 20 μm or more that is less than 40 days or that has no evidence of excessive carcinogenicity in an intraperitoneal test or that has no associated pathogenicity or tumor development in a long-term respiratory test (EU Directive 97 / 69 / EC Nota Q (carcinogenic exclusion)). Examples of such biodegradable mineral fibers include SiO ₂ —Al ₂ O ₃ —CaO—MgO—FeO—Na ₂ O fibers and the like, and include SiO ₂ , Al ₂ O ₃ , CaO, MgO, FeO, Na. Examples thereof include fibers containing ₂ O or the like in any combination. As a commercial item, LAPINUS FIBERS B.M. V. Roxul series ("Roxul" is a registered trademark) manufactured by the same company. “Roxul” includes SiO ₂ , Al ₂ O ₃ , CaO, MgO, FeO, Na ₂ O and the like.

  As the metal fiber, iron-based fiber, titanium fiber, zinc fiber, aluminum fiber or the like can be used, and one kind or a combination of two or more kinds can be used.

  The fiber base material is preferably contained in the friction material composition in an amount of 5 to 40% by mass, more preferably 5 to 35% by mass, and further preferably 6 to 30% by mass. When the content of the fiber base is 5 to 40% by mass, there is an effect of imparting an appropriate reinforcing effect to the friction material without causing adverse effects such as a significant decrease in effectiveness characteristics.

[Metal powder]
Moreover, metal powder can be mix | blended with the friction material composition of this invention. Examples of the metal powder include iron powder, tin powder, zinc powder, aluminum powder, and alloy powder thereof, and these can be used alone or in combination of two or more. The total content of the metal powder is preferably 0.5 to 5% by mass, more preferably 0.5 to 4% by mass, and further preferably 1 to 4% by mass. By making the content of metal powder 0.5% by mass or more in total, the metal powder forms TF on the surface of the disk rotor, and polishes or fills the polishing grooves of the disk rotor when new, thereby filling organically. A disk rotor surface on which TF due to a material, titanate, etc. and metal powder is easily fixed is generated, and the friction coefficient during light load braking is stabilized. Moreover, by making the total amount of metal powder 5 mass% or less, excessive adhesion between metals etc. can be suppressed and extreme wear deterioration of a friction material and a disk rotor can be avoided.

  Further, the metal powder that can be used in the friction material composition of the present invention is not subject to restrictions such as particle size and shape as long as it does not cause extreme deterioration of properties. For example, the shape may be a spherical shape manufactured by a general atomizing method or the like, or a columnar shape manufactured by a general cutting method or the like. Moreover, although the purity as a metal is preferably 90% or more, there is no problem even if the surface of the metal powder is changed to a metal oxide or the like by long-term storage of the metal powder and the friction material composition.

[Other ingredients]
Moreover, the friction material composition of this invention can mix | blend other materials as needed other than the said material.

<Friction material and friction member>
The friction material composition of the present invention can be used as a friction material for disc brake pads, brake linings, etc. of automobiles, or by subjecting the friction material composition of the present embodiment to a desired shape by performing steps such as molding, processing, and pasting. It can also be used as a friction material for facings, electromagnetic brakes and holding brakes.

The friction material composition of the present invention can be used as a friction member itself that becomes a friction surface to obtain a friction material. Examples of the friction material using the same include the following configurations.
(1) Configuration of only friction member (2) Configuration having a back metal and a friction member formed on the back metal and made of the friction material composition of the present invention to be a friction surface (3) Configuration of (2) above In the structure, a primer layer for the purpose of surface modification for enhancing the adhesion effect of the back metal between the back metal and the friction member, a configuration in which an adhesive layer for the purpose of bonding the back metal and the friction member is further interposed, etc. Can be mentioned.

  The backing metal is usually used as a friction member in order to improve the mechanical strength of the friction member. As the material, metal or fiber reinforced plastic can be used. For example, iron, stainless steel, inorganic fiber Examples include reinforced plastic and carbon fiber reinforced plastic. As the primer layer and the adhesive layer, those usually used for friction members such as brake shoes may be used.

  The friction material composition of the present invention can be produced by using a generally used method, and can be produced by heating and pressing the friction material composition of the present invention. In detail, for example, the friction material composition of the present embodiment is mixed with a Laedige mixer (“Laedige” is a registered trademark), a pressure kneader, an Eirich mixer (“Eirich” is a registered trademark), or the like. The mixture is uniformly mixed using a machine, this mixture is preformed in a molding die, and the resulting preform is molded under conditions of a molding temperature of 130 to 160 ° C., a molding pressure of 20 to 50 MPa, and a molding time of 2 to 10 minutes. The friction material of this embodiment can be obtained by molding and heat-treating the resulting molded product at 150 to 250 ° C. for 2 to 10 hours. In addition, you may perform a coating, a scorch process, a grinding | polishing process, etc. as needed.

Since the friction material composition of the present invention is excellent in stability of friction coefficient, wear resistance at high temperature, etc., it is useful as a “upholstery material” for friction members such as disc brake pads and brake linings. It can also be molded and used as an “underlaying material”.
The “upper material” is a friction material that becomes the friction surface of the friction member, and the “underlay material” is a friction material that is interposed between the friction material that becomes the friction surface of the friction member and the back metal. It is a layer for the purpose of improving the shear strength and crack resistance in the vicinity of the adhesion part with the back metal.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these.

<Examples 1-7 and Comparative Examples 1-7>
[Production of disc brake pads]
The materials were blended according to the blending ratios shown in Tables 1 and 2, and the friction material compositions of Examples 1 to 7 and Comparative Examples 1 to 7 were obtained.

This friction material composition was mixed with a Laedige mixer (manufactured by Matsubo Co., Ltd., trade name: Ladige mixer M20), and this mixture was preformed with a molding press (manufactured by Oji Machinery Co., Ltd.), and obtained. The preform is heated and pressure-molded with a backing metal (made of iron) made by Hitachi Automotive Systems, Ltd. using a molding press (made by Sanki Seiko Co., Ltd.) under conditions of a molding temperature of 145 ° C., a molding pressure of 35 MPa, and a molding time of 5 minutes. The molded product thus obtained was heat-treated at 200 ° C. for 4.5 hours, polished using a rotary polishing machine, subjected to scorch treatment at 500 ° C., and a disc brake pad (friction material thickness 9.5 mm, friction Material projection area 52 cm ² ) was obtained.

Various materials used in Examples and Comparative Examples are as follows.
[Binder]
-Resin A (phenol resin): HP491UP manufactured by Hitachi Chemical Co., Ltd.
-Resin B (phenol resin): PR1950W manufactured by Hitachi Chemical Co., Ltd.
[Organic filler]
・ Cashew dust: FF-1051 manufactured by Tohoku Kako Co., Ltd.
Rubber component A (tire rubber powder): CarQuest powder TPA
Rubber component B (nitrile butadiene rubber): Nipol 1411 manufactured by Nippon Zeon Co., Ltd.
[Inorganic filler]
・ Titanate A (potassium 8 titanate): Terraces TF-S manufactured by Otsuka Chemical Co., Ltd.
・ Titanate B (lithium potassium titanate): Terraces L manufactured by Otsuka Chemical Co., Ltd.
-Titanate C (magnesium potassium titanate): Terraces PCS manufactured by Otsuka Chemical Co., Ltd.
Barium sulfate, graphite, tin sulfide, mica, calcium hydroxide, abrasive A (zirconium silicate): MZ1000B manufactured by Daiichi Rare Element Chemical Industries, Ltd.
・ Grinding material B (zirconium oxide): BR-QZ manufactured by Daiichi Rare Element Chemical Industries, Ltd.
・ Grinding material C (magnesium oxide): Industrial magnesium oxide 2000 manufactured by Kyowa Chemical Industry Co., Ltd.
[Fiber base]
・ Aramid fiber (organic fiber)
・ Mineral fiber (inorganic fiber)
[Metal powder, metal fiber]
・ Iron fiber: GMT # 0
-Zinc powder: Zn-At-200 manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.
-Tin powder: AT-Sn No. 200 manufactured by Yamaishi Metal Co., Ltd.
Aluminum powder: VA-40 manufactured by Yamaishi Metal Co., Ltd.

  Various performances of the disc brake pads of Examples 1 to 7 and Comparative Examples 1 to 7 produced by the above-described method were evaluated using a brake dynamo tester (manufactured by Shin Nippon Toki Co., Ltd.). In the experiment, a general pin slide type collet caliper and a ventilated disc rotor (FC250 (gray cast iron)) manufactured by Kiriu Co., Ltd. were used, and evaluation was performed with a moment of inertia half that of Nissan Motor Co., Ltd., Skyline V35. went.

[Evaluation of efficacy characteristics]
In the test, braking at a vehicle speed of 40 km / h and 0.1 G was repeated 100 times at a disc rotor temperature of 50 ° C. at the start of braking, and the friction coefficient at the 100th braking was evaluated. Generally, since the surface of the friction material at the time of a new article is not accustomed, the contact area with the disk rotor is small, and furthermore, TF is not formed, so the friction coefficient is low. The friction coefficient increases and stabilizes with repeated braking, but the friction coefficient is difficult to stabilize in light load braking where the vehicle speed and deceleration and the disk rotor temperature are low as described above. Here, regarding the evaluation of the coefficient of friction, 0.37 to 0.43 is excellent as “◎”, 0.34 to 0.36 and 0.44 to 0.47 are good as “◯”, less than 0.34, and “X” is described in Tables 1 and 2 with 0.48 or more being inappropriate.

[Evaluation of wear resistance]
The test was based on JASO C427, and the amount of wear of the disk pad when the brake temperature before braking was 400 ° C. was measured and evaluated as wear resistance. Here, with respect to the evaluation of the abrasion amount, less than 0.60 mm is regarded as “Excellent”, 0.60 to 0.99 mm is regarded as “Good”, 1.00 mm or more is unsuitable and “X” is represented as Table 1 and Table 2. Respectively.

  Examples 1 to 7 showed the same level of friction coefficient and wear resistance as Comparative Example 7 containing copper. Examples 1 to 7 are Comparative Example 1 in which the content of cashew dust is extremely small, Comparative Example 2 in which the amount of abrasives is extremely large, Comparative Example 3 in which only potassium titanate is contained as titanate, and titanic acid. Compared with Comparative Example 4 containing only lithium potassium titanate as a salt, Comparative Example 5 with an extremely low abrasive content, and Comparative Example 6 with an extremely high cashew dust content, the friction coefficient and wear resistance are excellent. It is clear.

  Compared with the conventional product, the friction material composition of the present invention expresses a stable friction coefficient by forming an appropriate amount of TF even in light load braking without using copper with high environmental load. Of course, it is suitable for a friction material and a friction member such as a brake pad for a passenger car equipped with a regenerative cooperative brake for a passenger car.

Claims (5)

A friction material composition comprising a binder, an organic filler, an inorganic filler, and a fiber substrate;
Does not contain copper as an element, or the copper content does not exceed 0.5 mass%,
1 to 10% by mass of cashew dust,
Contains potassium titanate,
Furthermore, it contains at least one of lithium potassium titanate and magnesium potassium titanate,
A friction material composition containing 11 to 30% by mass of at least one of zirconium silicate, zirconium oxide, and magnesium oxide.   The friction material composition according to claim 1, wherein the total content of potassium titanate, lithium potassium titanate, and magnesium potassium titanate is 10 to 35 mass%.   The friction material composition according to claim 1 or 2, comprising at least one of iron, tin, zinc, and aluminum as metal powder or metal fiber in an amount of 0.5 to 5 mass%.   The friction material formed by shape | molding the friction material composition in any one of Claims 1-3.   A friction member obtained by integrating the friction material according to claim 4 and a back metal.