Composition for friction material formation, friction material, friction member, and disc brake pad for automobile

Abstract

To provide a composition for friction material formation which has a stable friction coefficient by a small number of times of fitting, exhibits a friction coefficient even in low temperature braking at 50°C, and can maintain a friction coefficient during high temperature fading.SOLUTION: A composition for friction material formation contains an aralkyl-modified resin, an aramid fiber and a cellulose fiber, and contains no copper or has a percentage content of copper of more than 0 mass% and 0.5 mass% or less in terms of an element.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a friction material-forming composition, a friction material, a friction member, and an automotive disc brake pad. [Background technology]

[0002] Conventionally, disc brakes have been used as braking devices for passenger vehicles, and disc brake pads, which consist of a friction material attached to a metal base member, are used as friction members. Friction materials are manufactured using a friction material composition containing a fibrous base material, a friction modifier, a binder, etc., through a manufacturing process that includes steps such as preforming, thermoforming, and finishing.

[0003] As a friction material composition for use in automobile disc brake pads, for example, a friction material composition containing 1 to 25 mass % of a fibrous base material including regenerated cellulose fibers, of which the content of regenerated cellulose fibers is 0.5 to 10 mass %, has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6867783 Summary of the Invention [Problem to be solved by the invention]

[0005] Automotive disc brake pads (hereinafter also referred to as "brake pads"), especially friction materials used in electric vehicles, require the following friction coefficient conditions, taking into account two factors: the contribution of regenerative braking and the increased vehicle weight due to the loading of batteries. First, it is desirable for the friction coefficient to be stable with a small number of break-in cycles. Furthermore, it is desirable for the friction coefficient to be fully exhibited even during low-temperature braking. Finally, it is desirable for the friction coefficient to be able to be maintained during high-temperature fade, assuming situations where the brakes are applied continuously, such as when descending a mountain or slope.

[0006] For example, the stability of the friction coefficient after a small number of grinding cycles can be evaluated by the value of the friction coefficient after 50 grinding cycles. Also, low-temperature braking can be evaluated by the friction coefficient at 50°C, and high-temperature fade can be evaluated by the minimum value of the friction coefficient during a fade test.

[0007] However, it is difficult for a friction material to achieve all of the following: a stable coefficient of friction with a small number of grinding cycles, a coefficient of friction during low-temperature braking, and a coefficient of friction during high-temperature fading.

[0008] The present disclosure has been made in consideration of the above-mentioned conventional circumstances, and aims to provide a friction material-forming composition that stabilizes the friction coefficient with a small number of grinding cycles, exhibits a friction coefficient even during low-temperature braking at 50°C, and is capable of maintaining the friction coefficient during high-temperature fade; a friction material obtained by molding the composition; and a friction member and an automotive disc brake pad that include the friction material. [Means for solving the problem]

[0009] Specific means for achieving the above object are as follows. <1> The fiber contains an aralkyl-modified resin, an aramid fiber, and a cellulose fiber, A friction material-forming composition that does not contain copper or has a copper content of more than 0 mass % and not more than 0.5 mass % on an elemental basis. <2> It contains at least two types of graphite with different average particle sizes, the average particle size of the graphite with the smaller average particle size being 50 nm to 30 μm, and the average particle size of the graphite with the larger average particle size being 150 μm to 600 μm. <1> The friction material forming composition according to claim 1. <3> Also contains tin sulfide <1> or <2> The friction material forming composition according to claim 1. <4> Also contains iron fibers <1> ~ <3> 10. The friction material-forming composition according to claim 9, wherein the friction material-forming composition is a tungsten carbide (TFT) or a tungsten carbide (TFT). <5> <1> ~ <4> 1. A friction material obtained by molding the friction material-forming composition according to any one of the above. <6> <1> ~ <4> 1. A friction member comprising a friction material formed by molding the friction material-forming composition according to any one of 1 to 8 above, and a backing metal. <7> <5> A disc brake pad for an automobile comprising the friction material according to claim 1. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, there are provided a friction material-forming composition that stabilizes the friction coefficient with a small number of grinding cycles, exhibits a friction coefficient even during low-temperature braking at 50°C, and is capable of maintaining the friction coefficient during high-temperature fade; a friction material obtained by molding the composition; and a friction member and an automotive disc brake pad that include the friction material. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0012] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, the particles corresponding to each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, the term "layer" includes cases where the layer is formed over the entire area when the area in which the layer exists is observed, as well as cases where the layer is formed over only a portion of the area. The average particle size of particles refers to the 50% (median) diameter (D50) determined from the volume distribution of particle size distribution measured using a laser diffraction / scattering particle size distribution analyzer. The average particle size can be measured, for example, using an LA-920 (manufactured by Horiba, Ltd.).

[0013] [Composition for forming friction material] The friction material-forming composition of the present disclosure is a composition that contains an aralkyl-modified resin, aramid fibers, and cellulose fibers, and does not contain copper, or the copper content is greater than 0 mass% and not more than 0.5 mass% on an elemental basis. The friction material-forming composition of the present disclosure may contain other components in addition to the above components.

[0014] By including the above components in the friction material-forming composition of the present disclosure, the friction coefficient becomes stable with fewer grinding cycles, and the friction coefficient is maintained even during low-temperature braking at 50°C, and the friction coefficient can also be maintained during high-temperature fade.

[0015] (Aralkyl-modified resin) The friction material-forming composition of the present disclosure contains an aralkyl-modified resin. By combining the aralkyl-modified resin with aramid fibers and cellulose fibers, the friction material tends to have an excellent coefficient of friction even during low-temperature braking at 50°C. The friction material-forming composition of the present disclosure may contain one or more aralkyl-modified resins.

[0016] Examples of the aralkyl-modified resin include aralkyl-modified epoxy resins and aralkyl-modified phenolic resins.

[0017] In the friction material-forming composition of the present disclosure, the content of the aralkyl-modified resin may be 1 mass % to 10 mass %, 2 mass % to 8 mass %, 2.5 mass % to 7 mass %, 3 mass % to 6 mass %, or 3.5 mass % to 5 mass %, relative to the total amount of the friction material-forming composition.

[0018] In the friction material-forming composition of the present disclosure, the content of the aralkyl-modified resin may be 40% by mass to 80% by mass, 45% by mass to 75% by mass, or 50% by mass to 70% by mass, based on the total amount of the aralkyl-modified resin, aramid fibers, and cellulose fibers.

[0019] (aramid fiber) The friction material-forming composition of the present disclosure contains aramid fibers, which tend to improve the heat resistance of the friction material. The friction material-forming composition of the present disclosure may contain one or more types of aramid fibers.

[0020] The fiber length of the aramid fiber is not particularly limited, and may be 5000 μm or less, or from the viewpoint of dispersion, may be 2000 μm or less, or may be 1500 μm or less. The lower limit of the fiber length of the cellulose fibers is not particularly limited, and may be 500 μm or more, or 800 μm or more.

[0021] The fiber length of aramid fiber refers to the number-average fiber length, which indicates the average length of aramid fibers. The fiber length of aramid fiber refers to the arithmetic mean when 50 randomly selected aramid fibers are measured with an electron microscope. The fiber diameter of aramid fiber refers to the number-average fiber diameter, which indicates the average diameter of aramid fibers. The fiber diameter of aramid fiber refers to the arithmetic mean when 50 randomly selected aramid fibers are measured with an electron microscope.

[0022] The fiber diameter of the aramid fiber is not particularly limited, and may be 5 μm to 100 μm, 10 μm to 50 μm, or 15 μm to 30 μm.

[0023] In the friction material-forming composition of the present disclosure, the content of aramid fibers may be 0.5 mass % to 5 mass %, 1 mass % to 4 mass %, 1.2 mass % to 3 mass %, 1.5 mass % to 2.5 mass %, or 1.7 mass % to 2.3 mass % relative to the total amount of the friction material-forming composition.

[0024] In the friction material-forming composition of the present disclosure, the content of the aramid fiber may be 15% by mass to 40% by mass, 20% by mass to 35% by mass, or 25% by mass to 32% by mass, based on the total amount of the aralkyl-modified resin, the aramid fiber, and the cellulose fiber.

[0025] (cellulose fiber) The friction material-forming composition of the present disclosure contains cellulose fibers. The cellulose fibers contribute to the reinforcing effect of the friction material. By combining the cellulose fibers with the aralkyl-modified resin and the aramid fibers, the friction material tends to have an excellent coefficient of friction even during low-temperature braking at 50°C. The friction material-forming composition of the present disclosure may contain one or more types of cellulose fibers.

[0026] Examples of cellulose fibers include natural cellulose fibers, regenerated cellulose fibers, and pulp pulp products. Regenerated cellulose fibers are obtained by chemically dissolving natural cellulose contained in wood pulp, cotton, etc. using a solvent or the like, extracting the cellulose, spinning it, and then remaking it into fibers. Known cellulose fibers can be used.

[0027] Examples of regenerated cellulose fibers include rayon fibers, lyocell fibers, cupra fibers, and polynosic fibers.

[0028] The pulp powder is made by crushing kraft pulp, which has not been spun into fibers by chemical treatment, and any known product can be used. Crushed recycled paper pulp can also be used.

[0029] The fiber length of the cellulose fibers is not particularly limited, and may be 5000 μm or less, or from the viewpoint of dispersion, may be less than 2000 μm or may be 1000 μm or less. The lower limit of the fiber length of the cellulose fibers is not particularly limited, and may be 500 μm or more.

[0030] The fiber diameter of the cellulose fibers is not particularly limited, and may be 5 μm to 100 μm, 10 μm to 50 μm, or 15 μm to 30 μm.

[0031] The fiber length of cellulose fibers refers to the number-average fiber length, which indicates the average length of cellulose fibers. The fiber length of cellulose fibers is the arithmetic mean when 50 randomly selected cellulose fibers are measured with an electron microscope. The fiber diameter of cellulose fibers refers to the number-average fiber diameter, which indicates the average diameter of cellulose fibers. The fiber diameter of cellulose fibers refers to the arithmetic mean when 50 randomly selected cellulose fibers are measured with an electron microscope.

[0032] When the cellulose fibers are regenerated cellulose fibers, the fiber length or fiber diameter of the cellulose fibers can be adjusted by adjusting the concentration of the spinning dope during the production of the regenerated cellulose, adjusting the spinning conditions, etc.

[0033] From the viewpoint of suppressing fade, the content of cellulose fibers may be 0.1 mass % or more, 0.3 mass % or more, or 0.5 mass % or more, based on the total amount of the friction material-forming composition. The cellulose fiber content may be 5% by mass or less, 3% by mass or less, or 1.5% by mass or less, based on the total amount of the friction material-forming composition, and from the viewpoint of suppressing rotor wear, may be 1.2% by mass or less.

[0034] In the friction material-forming composition of the present disclosure, the content of cellulose fibers may be 2% by mass to 25% by mass, 3% by mass to 20% by mass, or 5% by mass to 15% by mass, based on the total amount of the aralkyl-modified resin, aramid fibers, and cellulose fibers.

[0035] In the friction material-forming composition of the present disclosure, the mass ratio of cellulose fiber to aramid fiber, cellulose fiber:aramid fiber, may be 1:1 to 1:10, 1:1.5 to 1:6, or 1:2 to 1:5.

[0036] The friction material-forming composition of the present disclosure may or may not contain fibers other than cellulose fibers and aramid fibers.

[0037] Examples of other fibers include inorganic fibers, metal fibers, organic fibers other than cellulose fibers and aramid fibers, and carbon-based fibers.

[0038] Examples of inorganic fibers include ceramic fibers, biodegradable ceramic fibers, mineral fibers, glass fibers, potassium titanate fibers, silicate fibers, and wollastonite.

[0039] The carbon fiber referred to here may be flame-resistant fiber, pitch-based carbon fiber, PAN (polyacrylonitrile)-based carbon fiber, activated carbon fiber, or the like.

[0040] The term "mineral fiber" as used herein refers to artificial inorganic fibers that are melt-spun using blast furnace slag such as slag wool, basalt such as basalt fiber, or other natural rocks as the main component. Mineral fibers are preferably fibers derived from natural minerals containing Al. Specific examples include SiO, AlO, CaO, MgO, FeO, and NaO. Of these, those containing Al are preferred.

[0041] As the metal fibers, copper or copper alloy fibers can be used in order to improve crack resistance and abrasion resistance. As the copper or copper alloy fibers, copper fibers, brass fibers, bronze fibers, etc. can be used. When the metal fibers include copper or copper alloy fibers, the copper content in the friction material-forming composition may be more than 0 mass % and 0.5 mass % or less on an elemental basis.

[0042] Furthermore, metal fibers other than copper and copper alloys may be used as the metal fibers. Metal fibers other than copper and copper alloys may be contained from the viewpoint of improving the coefficient of friction and crack resistance.

[0043] Examples of metal fibers other than copper and copper alloys include fibers of simple metals or alloys such as aluminum, iron, zinc, tin, titanium, nickel, magnesium, and silicone, and fibers primarily composed of metals such as cast iron fibers. The friction material-forming composition of the present disclosure preferably contains iron fibers from the viewpoint of improving the friction coefficient of the friction material during low-temperature braking at 50°C. When the friction material-forming composition of the present disclosure contains iron fibers, the content of the iron fibers may be 1 mass % to 10 mass %, 1.5 mass % to 5 mass %, or 2 mass % to 4 mass % relative to the total amount of the friction material-forming composition.

[0044] Examples of organic fibers include acrylic fibers and phenolic resin fibers which may have a crosslinked structure.

[0045] (Inorganic filler) The friction material-forming composition of the present disclosure contains an inorganic filler. The inorganic filler may be used alone or in combination of two or more kinds.

[0046] Examples of inorganic fillers include graphite, zirconia (zirconium dioxide), metal sulfides, mica, titanates, coke, calcium hydroxide (slaked lime), calcium oxide, sodium carbonate, calcium carbonate, magnesium carbonate, barium sulfate, dolomite, iron oxide, vermiculite, calcium sulfate, talc, clay, zeolite, zircon (zirconium silicate), mullite, chromite, titanium oxide, magnesium oxide, silica, iron oxide, garnet, aluminas such as α-alumina and γ-alumina, and silicon carbide.

[0047] Examples of graphite include artificial graphite such as petroleum pitch-based and coal pitch-based graphite, and natural graphite.

[0048] The friction material-forming composition of the present disclosure may contain graphite, or may contain two or more types of graphite. A preferred combination of the two or more types of graphite is one in which the graphite with a smaller average particle size (also referred to as small particle size graphite) has an average particle size of 50 nm to 30 μm and the graphite with a larger average particle size (also referred to as large particle size graphite) has an average particle size of 150 μm to 600 μm. By combining small particle size graphite and large particle size graphite, the coefficient of friction tends to be stabilized with fewer grinding cycles, and the coefficient of friction during high temperature fade also tends to improve.

[0049] When the friction material-forming composition of the present disclosure contains graphite (preferably small particle size graphite and large particle size graphite), the graphite content may be 1 mass % to 12 mass %, 2 mass % to 10 mass %, or 3 mass % to 8 mass % relative to the total amount of the friction material-forming composition.

[0050] When the friction material-forming composition of the present disclosure contains small particle size graphite and large particle size graphite, the mass ratio of the small particle size graphite to the large particle size graphite, small particle size graphite:large particle size graphite, may be 1:0.5 to 1:10, 1:1 to 1:6, or 1:2 to 1:5.

[0051] Examples of metal sulfides include antimony trisulfide, tin sulfide, tin disulfide, molybdenum disulfide, iron sulfide, iron disulfide, bismuth sulfide, zinc sulfide, and tungsten disulfide. The friction material-forming composition of the present disclosure preferably contains tin sulfide. When the friction material-forming composition of the present disclosure contains tin sulfide, the tin sulfide content may be 0.5% by mass to 6% by mass, 1% by mass to 5% by mass, or 1.5% by mass to 3% by mass, based on the total amount of the friction material-forming composition.

[0052] Examples of titanates include potassium titanate, lithium potassium titanate, sodium titanate, and magnesium potassium titanate.

[0053] The inorganic filler may include at least one selected from the group consisting of graphite, zirconia, metal sulfide, titanate, barium sulfate, calcium hydroxide, zircon, and alumina.

[0054] The content of the inorganic filler may be 30% by mass to 85% by mass, 50% by mass to 80% by mass, or 60% by mass to 80% by mass, based on the total amount of the friction material-forming composition.

[0055] The inorganic filler may include zirconia. The content of zirconia is preferably 40% by mass or less, more preferably 10% by mass to 35% by mass, and even more preferably 15% by mass to 30% by mass, based on the total amount of the friction material-forming composition. The average particle size of zirconia is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm.

[0056] The inorganic filler may include titanate (preferably potassium titanate, lithium potassium titanate, or magnesium potassium titanate). The content of titanate (preferably potassium titanate, lithium potassium titanate, or magnesium potassium titanate) is preferably 40 mass% or less, more preferably 10 mass% to 35 mass%, and even more preferably 15 mass% to 30 mass%, based on the total amount of the friction material-forming composition.

[0057] The inorganic filler may include barium sulfate. The content of barium sulfate is preferably 20% by mass or less, more preferably 5% by mass to 15% by mass, and even more preferably 5% by mass to 12% by mass, based on the total amount of the friction material-forming composition.

[0058] (organic filler) The friction material-forming composition of the present disclosure may contain an organic filler. Examples of organic fillers include friction dust and cashew dust. The organic filler may be used alone or in combination of two or more kinds.

[0059] The content of the organic filler may be 4% by mass to 20% by mass, 5% by mass to 15% by mass, or 6% by mass to 10% by mass, based on the total amount of the friction material-forming composition.

[0060] (Binding material) The friction material-forming composition of the present disclosure may contain a binder. The binder binds and integrates the components contained in the friction-material-forming composition, thereby providing the composition with a desired shape and strength. There are no particular limitations on the binder contained in the friction-material-forming composition of the present disclosure, and any known thermosetting resin used as a binder for friction materials can be used.

[0061] Examples of thermosetting resins include phenolic resins (resol-type phenolic resins and novolac-type phenolic resins), epoxy resins, polyimide resins, etc. Further examples include various modified phenolic resins such as acrylic-modified phenolic resins, silicone-modified phenolic resins, cashew-modified phenolic resins, and epoxy-modified phenolic resins. These may be used alone or in combination of two or more. It is particularly preferable to use at least one selected from the group consisting of phenolic resins, acrylic-modified phenolic resins, silicone-modified phenolic resins, and alkylbenzene-modified phenolic resins, as these resins provide good heat resistance, moldability, and coefficient of friction.

[0062] The binder content is preferably 4% by mass to 20% by mass, more preferably 5% by mass to 15% by mass, and even more preferably 6% by mass to 10% by mass, based on the total amount of the friction material-forming composition. By setting the binder content within the range of 4% by mass to 20% by mass, based on the total amount of the friction material-forming composition, a decrease in the strength of the friction material can be further suppressed.

[0063] (Other ingredients) The friction material-forming composition of the present disclosure may contain other materials in addition to the above-mentioned components, as needed. Other materials include fluorine-based polymers such as PTFE (polytetrafluoroethylene), rubber powder, and metal powder. The other materials may be used alone or in combination of two or more.

[0064] Examples of rubber components that make up rubber powder include tire rubber, natural rubber, acrylonitrile-butadiene rubber (NBR), acrylic rubber, isoprene rubber, polybutadiene rubber (BR), styrene butadiene rubber (SBR), and silicone rubber. It may also be tire powder made of ear rubber.

[0065] The form of the friction material-forming composition of the present disclosure is not particularly limited, and may be in the form of powder, tablet, or the like.

[0066] [Friction material] The friction material of the present disclosure is a member obtained by molding the friction-material-forming composition of the present disclosure. The friction material of the present disclosure can be used as a friction material for disc brake pads, brake linings, and the like used in automobiles, etc.

[0067] The friction material of the present disclosure can be produced by molding the friction material-forming composition of the present disclosure using a commonly used method. Preferably, it is produced by hot-press molding. Specifically, the friction material-forming composition of the present disclosure is mixed using a mixer such as a Lödige mixer, a pressure kneader, or an Eirich mixer, and the mixture is preformed in a molding die. The resulting preform is heated and molded at a molding temperature of 140°C to 160°C and a molding pressure of 20 MPa to 50 MPa for 4 to 10 minutes, and the resulting molded product is heat-treated at 180°C to 250°C for 2 to 10 hours. Furthermore, coating, scorching, polishing, etc. may be performed as needed.

[0068] [Friction material] The friction member of the present disclosure includes the friction material of the present disclosure. In the friction member of the present disclosure, the friction material of the present disclosure preferably constitutes a friction surface of the friction member. The friction member of the present disclosure may have, for example, the following configuration. (1) Composition of friction material only (2) A configuration including a backing metal and the friction material of the present disclosure that serves as a friction surface provided on the backing metal. (3) In the configuration of (2) above, a primer layer for surface modification to enhance the adhesive effect of the backing metal to the friction material and an adhesive layer for bonding the backing metal to the friction material are further interposed between the backing metal and the friction material. [Example]

[0069] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples in any way.

[0070] [Making disc brake pads] Friction material-forming compositions of Examples and Comparative Examples were obtained by blending materials according to the blending ratios (mass %, wt %) shown in Table 1. The blending amount of each component in Table 1 is expressed in mass % of the friction material-forming composition. In Table 1, "-" indicates that the corresponding component is not contained.

[0071] The silicone-modified resin used was a silicone-modified phenolic resin, the aralkyl-modified resin used was an aralkyl-modified phenolic resin, and the titanate used was a 1:1 mixture of potassium titanate and lithium potassium titanate. The following components were used as aramid fibers, cellulose fibers, small particle size graphite, and large particle size graphite. The average particle size refers to D50. Aramid fiber average fiber length: 1.17 mm Cellulose fiber average fiber length: 900 μm Small particle size graphite, average particle size: 8 μm Large particle size graphite, average particle size: 424 μm

[0072] This friction material-forming composition was mixed in a Lödige mixer (manufactured by Matsubo Corporation, product name: Lödige mixer M20), and this mixture was hot-pressed and molded together with an iron backing (thickness 6 mm) using a molding press (manufactured by Technomarusichi Corporation). The resulting molded product was heat-treated at 200°C for 3.5 hours and polished using a rotary polisher. The molded product was then scorched for 5 minutes at 500°C to produce a 10 mm thick, 60 cm projected area. 2 A disc brake pad having the above friction material was manufactured.

[0073] Using the disc brake pads manufactured in each example and each comparative example, tests were conducted in accordance with the test conditions in Table 2 to evaluate the minimum values ​​of μ after 50 grindings, μ at 50°C, 30 km / h, 0.3 G, and μ during fade. In Tables 2 and 3, the unit of rotor temperature before braking is °C, the unit of braking interval is seconds, the unit of initial speed is km / h, and the unit of deceleration is m / s. 2 is.

[0074] Table 1 shows the results of the 50th friction test, the friction at 50°C, 30km / h (kph) and 0.3G, and the minimum friction value (min-min μ) during the 1st Fade test, which is an indicator of fade suppression. The evaluation criteria for each of these items are as follows. A rating of B or higher for each item is considered good.

[0075] -50th round of negotiations μ- A: 0.40 or more B: 0.38 or more and less than 0.40 C: Less than 0.38 -50℃ 30km / h 0.3G μ- A: 0.40 or more B: 0.38 or more and less than 0.40 C: Less than 0.38 -Minimum μ value during 1st Fade test- A: 0.22 or more B: 0.20 or more and less than 0.22 C: Less than 0.20

[0076] [Table 1]

[0077] [Table 2]

[0078] As shown in Table 1, in each example, the evaluation results of μ at the 50th lapping, μ at 50° C., 30 km / h, 0.3 G, and the minimum value of μ during the 1st Fade test were all B or higher. On the other hand, in each of the comparative examples, at least one of the evaluation results of μ at the 50th grinding, μ at 50° C., 30 km / h, 0.3 G, and the minimum value of μ during fade was C.

Claims

1. The fiber contains an aralkyl-modified resin, an aramid fiber, and a cellulose fiber, A friction material-forming composition that does not contain copper or has a copper content of more than 0 mass % and not more than 0.5 mass % on an elemental basis.

2. 2. The friction material-forming composition according to claim 1, which contains at least two types of graphite having different average particle sizes, wherein the average particle size of the graphite having a smaller average particle size is 50 nm to 30 μm, and the average particle size of the graphite having a larger average particle size is 150 μm to 600 μm.

3. The friction material-forming composition according to claim 1, further comprising tin sulfide.

4. The friction material-forming composition according to claim 1 , further comprising iron fibers.

5. A friction material obtained by molding the friction material-forming composition according to any one of claims 1 to 4.

6. A friction member comprising a friction material formed by molding the friction material-forming composition according to any one of claims 1 to 4, and a backing metal.

7. A disc brake pad for an automobile, comprising the friction material according to claim 5.

Images