Friction member and method for manufacturing friction member

Abstract

Provided are: a friction member including a friction material composed of a thermoplastic resin composition and having a high friction coefficient; and a method for manufacturing the friction member. More specifically, provided is a method for manufacturing a friction member including at least a friction material and a back plate supporting the friction material, the method being characterized in that: the method includes a step for forming the friction material and the back plate in the same molding cycle by melt-molding a resin composition at the softening / pour temperature of a thermoplastic resin (A) or higher; and, in the resin composition, the thermoplastic resin (A), having a melt viscosity (V6) of 30 Pa•s or less and a flow softening temperature of 130°C or higher, and an inorganic filler (B) are blended as essential components, and the blending amount of the thermoplastic resin (A) is 50 parts by mass or less with respect to 100 parts by mass of the resin composition.

Description

Friction member and method of manufacturing the same

[0001] The present invention relates to a friction member and a method for manufacturing the friction member.

[0002] Friction members (or friction materials) used in brake materials (e.g., brake pads, brake discs) for vehicles, industrial machinery, robots, etc. are required to have various performance characteristics, such as a high friction coefficient, wear resistance, heat resistance, and mechanical strength. In recent years, efforts to reuse materials have been actively considered toward realizing a sustainable society, and the use of materials with excellent recyclability has become a design requirement. Conventionally, friction materials, which are one of the components of brakes, can be broadly divided into organic and inorganic types. Organic types primarily use thermosetting resin compositions containing fillers. For example, Patent Document 1 discloses a thermosetting resin composition for friction materials in which lignocellulose nanofibers are dispersed in a thermosetting resin. Patent Document 2 discloses a thermosetting resin composition for friction materials containing a phenolic resin, hexamethylenetetramine, and a triazine compound.

[0003] However, thermosetting resins have problems such as longer processing times and poor recyclability compared to thermoplastic resins. On the other hand, the development of engineering plastics and super engineering plastics, which are thermoplastic resins with higher melting points than conventional general-purpose thermoplastic resins, has made it possible to produce thermoplastic resin compositions with superior heat resistance, and it is now possible to achieve the heat resistance required for friction components such as those described above. In addition, depending on the compounding materials, it is expected that the friction and wear properties of these resin compositions can be improved, and there is a growing demand for material development.

[0004] JP 2018-131477 A JP 2020-169245 A

[0005] Therefore, an object of the present invention is to provide a friction member having a high friction coefficient, which includes a friction material made of a thermoplastic resin composition, and a method for manufacturing the friction member.

[0006] That is, the present disclosure relates to a method for manufacturing a friction member including at least a friction material and a backing plate that supports the friction material, the method comprising: a step of melt-molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A) to form the friction material and the backing plate in the same molding cycle; the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B); and the amount of the thermoplastic resin (A) blended is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0007] The present disclosure also relates to a method for manufacturing a friction member including at least a friction material and a backing plate that supports the friction material, the method comprising the steps of: melt-molding a resin composition into a mold into which the backing plate is inserted at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A) to form a friction material; the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B); and the amount of the thermoplastic resin (A) blended is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0008] The present disclosure also relates to a friction member including at least a friction material and a backing plate that supports the friction material, wherein the friction material and the backing plate are formed by melt-molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or higher, and an inorganic filler (B), and the amount of the thermoplastic resin (A) blended is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0009] The present disclosure also relates to a friction member including at least a friction material and a backing plate that supports the friction material, wherein the friction material is obtained by melt-molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the backing plate is at least one member selected from the group consisting of a metal member and a ceramic member, the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0010] According to the present invention, it is possible to provide a friction member having a high friction coefficient, which includes a friction material made of a thermoplastic resin composition, and a method for manufacturing the friction member.

[0011] Hereinafter, an embodiment of the present invention will be described in detail, but the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are specified for a specific parameter, any upper and lower limit values ​​can be combined to form a suitable numerical range.

[0012] A method for manufacturing a friction member according to this embodiment is a method for manufacturing a friction member comprising at least a friction material and a backing plate supporting the friction material, the method comprising the steps of melt-molding a resin composition to form the friction material and the backing plate in the same molding cycle, the resin composition comprising, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) blended is 50 parts by mass or less per 100 parts by mass of the resin composition. This will be explained below.

[0013] In this disclosure, a friction member refers to a brake pad in a disc brake, a brake shoe in a drum brake, or a rotor in an electromagnetic brake, and is composed of a friction material (brake lining) and a backing plate. The backing plate is a member that supports the friction material and is provided on the side of the friction member that does not come into contact with the braked member. The braked member refers to, for example, the brake drum in a drum brake, the disc rotor in a disc brake, or the armature in an electromagnetic brake.

[0014] In this embodiment, the method of melt-molding the resin composition to form the friction material and the backing plate is not particularly limited as long as it does not impair the effects of the present invention, and known methods and devices can be used. For example, various melt-molding methods such as injection molding, compression molding, extrusion molding of composites, sheets, pipes, etc., pultrusion molding, blow molding, and transfer molding are possible, but the composition is particularly suitable for injection molding applications due to its excellent releasability. When molding by injection molding, the molding conditions are not particularly limited, and molding can be performed using ordinary methods. For example, in an injection molding machine, the resin composition is melted at a temperature range above the softening flow temperature of the thermoplastic resin (A), preferably at a temperature range of above that temperature +10°C, more preferably at a temperature range of above that temperature +10°C to above that temperature +100°C, and even more preferably at a temperature range of above that temperature +20°C to above that temperature +50°C, and then the resin composition is injected into a mold through a resin discharge port and molded. In this case, the mold temperature can also be set to a known temperature range, for example, room temperature (23°C) to 300°C, preferably 130 to 190°C.

[0015] In this embodiment, the friction material and backing plate are formed in the same molding cycle. The same molding cycle means that they are molded within a single melt-solidification cycle. Specifically, the friction material and backing plate are molded by performing two steps in this order, once each: a plasticization step in which the resin is heated to a temperature above its melting point to melt it, and a cooling step in which the resin melted in the plasticization step is cooled and solidified in a mold at a temperature below its crystallization temperature. This does not include a case in which the friction material and backing plate are formed in separate molding cycles and then integrated in a subsequent process.

[0016] The method for manufacturing a friction member according to this embodiment also includes a configuration in which the friction material also functions as a backing plate.

[0017] Resin Composition: The method for producing a friction member of the present disclosure involves melt-molding a resin composition to form the friction material and the backing plate in the same molding cycle. The resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or higher, and an inorganic filler (B), and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition. This is explained below.

[0018] Thermoplastic Resin (A) In the present embodiment, the thermoplastic resin (A) is not particularly limited as long as it has a melt viscosity (V6) of 30 Pa·s or less and a flow softening temperature of 130°C or more, and known materials can be used. Examples of suitable thermoplastic resins include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamide-6 (nylon-6), polyamide-11 (nylon-11), polyamide-12 (nylon-12), polyamide-46 (nylon-46), polyamide-66 (nylon-66), polyamide-610 (nylon-610), polyamide-6T (nylon-6T), polyamide-6I (nylon-6I), polyamide-9T (nylon-9T), polyamide-M5T (nylon-M5T), and polymetaxylene adipamide (nylon-MXD6); and ethylene-unsaturated copolymers such as ethylene-vinyl ester copolymers and ethylene-unsaturated carboxylic acid ester copolymers. Examples of suitable thermoplastic resins include ester copolymers, ethylene-unsaturated carboxylic acid copolymers or ionomer resins thereof, chlorine-based resins such as polyvinyl chloride and polyvinylidene chloride, fluorine-based resins such as polytetrafluoroethylene, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride and polyvinyl fluoride, polystyrene resins such as syndiotactic polystyrene, polyether-based resins such as polyether ether ketone resin, polyether ketone resin and polyether ketone ketone, polycarbonate resins, polyarylene sulfide resins typified by polyphenylene sulfide resins, polyphenylene oxide resins, polyvinyl acetate resins, polyacrylonitrile resins, liquid crystal polymers (LCPs), etc. One selected from these thermoplastic resins may be used alone, or two or more may be used in combination. Among these, from the viewpoints of heat resistance and low water absorption, engineering plastics or super engineering plastics are preferred, and polybutylene terephthalate, polyamide-6T (nylon-6T), polyamide-9T (nylon-9T), polyamide-10T (nylon-10T), polymetaxylene adipamide (nylon-MXD6), and polyarylene sulfide resin (hereinafter abbreviated as PAS) are more preferred, with PAS resin being particularly preferred.

[0019] When a PAS resin is used as the thermoplastic resin (A), its non-Newtonian index is not particularly limited, but is preferably in the range of 0.90 to 2.00. However, in the present invention, the non-Newtonian index (N value) is a value calculated using the following formula after measuring the shear rate (SR) and shear stress (SS) using a capillograph under conditions of a melting point of +20°C and a ratio of the orifice length (L) to the orifice diameter (D), L / D = 40. The closer the non-Newtonian index (N value) is to 1, the more linear the structure is, and the higher the non-Newtonian index (N value), the more branched the structure is.

[0020] [where SR is the shear rate (sec －１ ), SS is the shear stress (dyne / cm ２ ), and K denotes a constant.

[0021] The melt viscosity (V6) of the thermoplastic resin (A) used in this embodiment has a good balance between processability and mechanical strength, and is measured at 300°C with a melt viscosity (V6) of 30 Pa s or less, preferably 20 Pa s or less, and more preferably 10 Pa s or less. There is no particular restriction on the lower limit of the melt viscosity (V6), but from the viewpoint of mechanical strength, 2 Pa s or more is preferred. However, the melt viscosity (V6) is measured using a Shimadzu CFT-500D flow tester for a PAS resin at a temperature equal to the softening flow temperature of the thermoplastic resin (A) + 20°C, under a load of 1.96 MPa, using an orifice having an orifice length / orifice diameter ratio of 10 / 1, and is the measured value of the melt viscosity after holding for 6 minutes. In the present disclosure, the temperature at which the thermoplastic resin (A) becomes softened and flowable upon heating (which may be the melting point in the case of a crystalline resin, or the glass transition point in the case of a non-crystalline resin) is simply referred to as the "softening and flow temperature."

[0022] From the viewpoint of excellent friction and wear properties and dimensional stability, the blending amount of the thermoplastic resin (A) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, relative to 100 parts by mass of the resin composition. From the viewpoint of moldability, the blending amount is more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, relative to 100 parts by mass of the resin composition.

[0023] The thermoplastic resin (A) used in this embodiment may also be a recycled thermoplastic resin. When the thermoplastic resin (A) used in this embodiment contains the recycled material, the proportion of the recycled material in the resin is not particularly limited, but is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. The processing of thermoplastic resin molded articles into recycled materials (recycling treatment) can be carried out by known methods. Examples include a method of fragmenting the molded article into chips or pellets by cutting or crushing, a method of dissolving the fragmented molded article in a solvent and then performing solid-liquid separation to remove fillers, and a method of contacting the fragmented molded article with a solvent to extract and remove components other than the thermoplastic resin. Recycling treatment is often carried out using recovered thermoplastic resin molded articles provided by consumers, out-of-spec thermoplastic resin molded articles provided by molded article manufacturers, and losses generated during molding (such as runners in injection molding). Using recycled thermoplastic resins reduces the amount of resin and molded article waste and reduces the environmental impact.

[0024] Inorganic filler (B) The inorganic filler (B) used in this embodiment can be any known or commonly used material as long as it does not impair the effects of the present invention, and examples thereof include fillers of various shapes such as granular, plate-like, and fibrous. For example, glass fiber, carbon fiber, glass beads, glass flakes, barium sulfate, clay, pyrophyllite, bentonite, sericite, mica, talc, attapulgite, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, zeolite, milled fiber, calcium sulfate, potassium titanate, lithium titanate, magnesium potassium titanate, sodium titanate, alumina, wollastonite, magnesium oxide, chromite, chromium oxide, copper, iron oxide, zirconium oxide, zirconium silicate, rock wool, and other fillers can also be used.

[0025] The amount of the inorganic filler (B) to be blended is not particularly limited, but from the viewpoint of excellent mechanical properties and dimensional stability, it is preferably 40 to 350 parts by mass, more preferably 50 to 320 parts by mass, and even more preferably 60 to 300 parts by mass relative to 100 parts by mass of the resin composition.

[0026]

[0033] In order to further improve the sliding properties, the resin composition according to this embodiment may contain a solid lubricant (C) as an optional component. In the present invention, the solid lubricant refers to a substance that is solid at room temperature (23°C) and has a dynamic friction coefficient of 0.2 or less.

[0027] The solid lubricant (C) applicable to this embodiment is not particularly limited and may be any known material. Examples include polytetrafluoroethylene (PTFE), polyethylene, graphite, boron nitride, molybdenum disulfide, carbon fiber, and melamine cyanurate. In particular, PTFE, polyethylene, and graphite are preferred from the viewpoints of sliding properties and processability.

[0028] When the resin composition according to the present embodiment contains the solid lubricant (C), the amount of the solid lubricant (C) is preferably 2 to 50 parts by mass, more preferably 4 to 40 parts by mass, per 100 parts by mass of the thermoplastic resin (A). This range is preferable because the resin composition has good processability and the molded product has excellent wear resistance and mechanical strength.

[0029] Organic Filler (D) From the viewpoint of further improving abrasion resistance and vibration damping properties, the resin composition according to this embodiment can contain an organic filler (D) as an optional component.

[0030] The organic filler (D) applicable to the present embodiment is not particularly limited and any known filler can be used. Examples thereof include aramid fiber, thermoplastic elastomer, thermosetting elastomer, ionomer, cashew particles, rosin, etc., and from the viewpoint of processability, thermoplastic elastomer, thermosetting elastomer, and ionomer are particularly preferred.

[0031] When the organic filler (D) is blended into the resin composition according to this embodiment, the blending amount thereof is preferably in the range of 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, per 100 parts by mass of the thermoplastic resin (A). In this range, the resin composition has good abrasion resistance and excellent vibration damping properties, which is preferable.

[0032] Examples of the thermoplastic elastomer include polyolefin elastomers, fluorine elastomers, and silicone elastomers, with polyolefin elastomers being preferred. Examples of the polyolefin elastomer include a homopolymer of an α-olefin, a copolymer of two or more α-olefins, and a copolymer of one or more α-olefins with a vinyl polymerizable compound having a functional group. Examples of the α-olefin include α-olefins having 2 or more to 8 or less carbon atoms, such as ethylene, propylene, and 1-butene. Examples of the functional group include a carboxy group, an acid anhydride group (—C(═O)OC(═O)—), an epoxy group, an amino group, a hydroxyl group, a mercapto group, an isocyanate group, and an oxazoline group. Examples of the vinyl polymerizable compound having a functional group include one or more of vinyl acetate; α,β-unsaturated carboxylic acids such as (meth)acrylic acid; alkyl esters of α,β-unsaturated carboxylic acids such as methyl acrylate, ethyl acrylate, and butyl acrylate; metal salts of α,β-unsaturated carboxylic acids such as ionomers (metals include alkali metals such as sodium, alkaline earth metals such as calcium, and zinc); glycidyl esters of α,β-unsaturated carboxylic acids such as glycidyl methacrylate; α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and derivatives of the above α,β-unsaturated dicarboxylic acids (monoesters, diesters, and acid anhydrides). The above-mentioned thermoplastic elastomers may be used alone or in combination of two or more.

[0033] In order to further increase the bonding strength, the resin composition according to the present embodiment may contain a silane coupling agent as an optional component, if necessary. The silane coupling agent is not particularly limited as long as it does not impair the effects of the present invention, but preferred examples include silane coupling agents having a functional group that reacts with a carboxy group, such as an epoxy group, an isocyanato group, an amino group, or a hydroxyl group. Examples of such silane coupling agents include epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, and γ-isocyanatopropyltrichlorosilane; amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane; and hydroxyl group-containing alkoxysilane compounds such as γ-hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane.

[0034] The resin composition according to the present embodiment may further contain, as optional components, known and commonly used additives such as colorants, antistatic agents, antioxidants, heat stabilizers, UV stabilizers, UV absorbers, foaming agents, flame retardants, flame retardant assistants, rust inhibitors, and mold release agents (metal salts or esters of fatty acids having 18 to 30 carbon atoms, including stearic acid or montanic acid, and polyolefin waxes such as polyethylene). These additives are not essential components, and may be used in an amount of, for example, preferably 0.01 part by mass or more, and preferably 1,000 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin (A), as appropriate for the purpose and application so as not to impair the effects of the present invention.

[0035] Another embodiment of the method for producing a friction member according to the present disclosure is a method for producing a friction member comprising at least a friction material and a backing plate supporting the friction member, the method comprising the steps of melt-molding a resin composition into a mold into which the backing plate is inserted at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A) to form a friction material, the resin composition comprising, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) blended is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0036] The configuration of the back plate used in this embodiment is not particularly limited, but for example, a resin material, a metal material, a ceramic material, or the like can be used.

[0037] In this embodiment, the resin member that can be applied to the back plate is not particularly limited as long as it does not impair the effects of the present invention, and can be made of a member made of a known resin composition.For example, thermoplastic resins such as polyester resin, polyamide resin, polyimide resin, polyetherimide resin, polycarbonate resin, polyphenylene ether resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyarylene sulfide resin, polyetherketone resin, polyarylate resin, polyethylene resin, polypropylene resin, polyethylene tetrafluoride resin, polyethylene difluoride resin, polystyrene resin, ABS resin, phenolic resin, urethane resin, liquid crystal polymer, etc.; epoxy resins such as bisphenol type epoxy resin, novolac type epoxy resin, epoxy resin having polyarylene ether structure, epoxy resin having alicyclic structure and aromatic structure in the repeating unit; silicone resins such as condensation type silicone resin, addition type silicone resin; resin compositions containing curable resins such as novolac type phenolic resin, bisphenol type phenolic resin, etc., can be used alone or in combination. In addition, as optional components, the above-mentioned thermoplastic elastomer, silane coupling agent, filler, additive, etc. can be blended. When a thermosetting resin is used, a curing agent (e.g., an amine-type curing agent, a phenolic resin-type curing agent, an acid anhydride-type curing agent, a latent curing agent, etc.), a curing accelerator (e.g., a phosphorus-based compound, a tertiary amine, an imidazole, an organic acid metal salt, a Lewis acid, an amine complex salt, etc.), etc. can also be blended. Among these, polyether ether ketone resin, polyarylene sulfide resin, and polyphenylene ether resin are preferred from the viewpoints of heat resistance, dimensional stability, and processability.

[0038] In this embodiment, the metal material that can be used for the back plate is not particularly limited as long as it does not impair the effects of the present invention, and any known metal material can be used, such as aluminum, copper, stainless steel, magnesium, iron, titanium, or an alloy containing any of these. More specifically, examples of the alloy include iron and alloys containing iron as the main component, such as stainless steel and steel, i.e., 20% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass, with carbon, silicon, manganese, chromium, tungsten, molybdenum, phosphorus, titanium, vanadium, nickel, zirconium, boron, etc. (hereinafter referred to as iron alloys); aluminum and alloys containing aluminum as the main component and also containing copper, manganese, silicon, magnesium, zinc, nickel, etc. (hereinafter referred to as aluminum alloys); magnesium and alloys containing magnesium as the main component and also containing zinc, aluminum, zirconium, etc. (hereinafter referred to as magnesium alloys); copper and alloys containing copper as the main component and also containing zinc, tin, phosphorus, nickel, magnesium, silicon, chromium, etc. (hereinafter referred to as copper alloys); and titanium and alloys containing titanium as the main component and also containing copper, manganese, silicon, magnesium, zinc, nickel, etc. (hereinafter referred to as titanium alloys). Among these, iron, iron alloys, aluminum alloys, magnesium alloys, copper alloys, and titanium alloys are more preferable, and iron alloys, aluminum alloys, and magnesium alloys are even more preferable. Of these, iron, iron alloys, and aluminum alloys are preferred from the viewpoints of strength and availability.

[0039] In this embodiment, the ceramic member that can be used for the back plate is not particularly limited as long as it does not impair the effects of the present invention, and members made of known ceramics can be used. Examples include oxide-based ceramics such as alumina, zirconia, and barium titanate; hydroxide-based ceramics such as hydroxyapatite; carbide-based ceramics such as silicon carbide; and nitride-based ceramics such as silicon nitride. Among these, zirconia and silicon carbide are preferred from the viewpoints of toughness and availability.

[0040] The surface of the member used for the back plate may also be roughened. Known surface roughening methods can be used, including (1) immersion in an aggressive aqueous solution or suspension, (2) anodizing, and (3) mechanical cutting by blasting or laser processing. Of these, (1) immersion in an aggressive aqueous solution or suspension or (2) anodizing is preferred for roughening the surface of metal members, and (3) mechanical cutting by blasting or laser processing is preferred for roughening the surface of resin or ceramic members. The surface roughness of the roughened back plate is not particularly limited, but an arithmetic mean roughness (Ra) of 5 μm or more is preferred.

[0041] A primer layer may be formed on the surface of a metal member that has undergone a metal surface treatment. The material constituting the primer layer is not particularly limited, but it is typically a primer resin material containing a resin component. The primer resin material is not particularly limited, and known materials can be used. Specific examples include known polyolefin-based primers, epoxy-based primers, and urethane-based primers. The primer layer can be formed by applying a solution or emulsion of the primer resin material to the metal member that has undergone the surface treatment. Examples of solvents used to prepare the solution include toluene, methyl ethyl ketone (MEK), and dimethylphosphoramide (DMF). Examples of emulsion media include aliphatic hydrocarbon media and water.

[0042] The process of melt-molding the resin composition into a mold with the backing plate inserted therein at a temperature equal to or higher than the softening flow temperature of the thermoplastic resin (A) to form a friction material is a so-called insert molding process, in which the backing plate is inserted into a mold of an injection molding machine, and then the backing plate is injection-molded using the resin composition. The apparatus and manufacturing method for the insert molding process are not particularly limited, and commercially available apparatus can be used, or the process can be carried out according to a conventional method.

[0043] The method for manufacturing a friction member according to the present disclosure may include a step of annealing the friction member. The optimal conditions for the annealing treatment are selected depending on the application or shape of the friction member. The annealing temperature is in a temperature range equal to or higher than the glass transition temperature of the thermoplastic resin (A), preferably in a temperature range equal to or higher than the glass transition temperature + 10°C, and more preferably in a temperature range equal to or higher than the glass transition temperature + 30°C. The annealing time is not particularly limited, but is preferably in a range of 0.5 hours or more, more preferably in a range of 1 hour or more. On the other hand, it is preferably in a range of 10 hours or less, more preferably in a range of 8 hours or less. This range is preferred because distortion of the resulting molded product is reduced. The annealing treatment may be performed in air, but is preferably performed in an inert gas such as nitrogen gas.

[0044] [Friction Member] The friction member of the present disclosure is a friction member including at least a friction material and a backing plate that supports the friction material, wherein the friction material and the backing plate are obtained by melt-molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the blending amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0045] Another embodiment of the friction member of the present disclosure is a friction member including at least a friction material and a backing plate that supports the friction material, wherein the friction material is obtained by melt-molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the backing plate is at least one member selected from the group consisting of a metal member and a ceramic member, the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the blending amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

[0046] Furthermore, the friction coefficient of the friction member according to this embodiment is not particularly limited, but both the maximum static friction coefficient and the dynamic friction coefficient are preferably 0.20 to 1.00, more preferably 0.30 to 0.80, and even more preferably 0.35 to 0.70. Within these ranges, the friction member has an excellent balance of friction characteristics, wear resistance, and sound vibration characteristics, which is preferable. The difference between the maximum static friction coefficient and the dynamic friction coefficient is preferably 0.50 or less, more preferably 0.30 or less, and even more preferably 0.25 or less. Within these ranges, the friction member has excellent friction characteristics and sound vibration characteristics, which is preferable. Specifically, if the difference between the maximum static friction coefficient and the dynamic friction coefficient is large, the friction behavior of the friction member will be unstable during use, and vibration and noise will likely occur.

[0047] The friction member according to this embodiment is characterized by excellent braking characteristics, such as frictional properties and wear resistance, and is therefore particularly suitable for use in braking parts such as brake parts and clutch parts. Specifically, it can be suitably used in parts such as electromagnetic brakes, electromagnetic clutches, disc brakes, drum brakes, rim brakes, servo brakes, roller brakes, and band brakes. The parts can be applied to braking systems used in a variety of fields, such as automobiles, motorcycles, bicycles, industrial machinery, agricultural machinery, railway vehicles, aircraft, elevators, and transportation devices.

[0048] The present invention will be described below using examples and comparative examples, but is not limited to these examples. Unless otherwise specified, "%" and "parts" are based on mass.

[0049] Examples 1-7, 9, and Comparative Examples 1-2: Each material was blended according to the composition and blending amounts listed in Table 1. These blended materials were then fed into a vented twin-screw extruder "TEX-30α (product name)" manufactured by The Japan Steel Works, Ltd., and melt-kneaded at a resin component output rate of 30 kg / hr, a screw rotation speed of 200 rpm, and a set resin temperature of 310°C to obtain pellets of the resin composition. Glass fiber was fed through a side feeder (S / T ratio 0.5), while the other materials were pre-mixed uniformly in a tumbler and then fed through the top feeder. The resulting pellets of the resin composition were dried for 2 hours in a gear oven at 140°C. The resulting pellets were fed into a Sumitomo Heavy Industries injection molding machine (SE-75D-HP) with a cylinder temperature set to 310°C, and injection molding was performed using a molding die (annular molded product with an inner diameter of 45 mm and an outer diameter of 60 mm) controlled at a mold temperature of 140°C. At that time, a back plate (disk-shaped, 60 mm in diameter) made of the material shown in Table 1 was placed in the mold in advance, and insert molding was performed on both sides of the back plate to obtain a friction member. When a resin member was used as the back plate, it was supplied to a Sumitomo Heavy Industries injection molding machine (SE-75D-HP) set at a cylinder temperature of 310 ° C., and injection molded using a molding mold (disk-shaped molded product, 60 mm in diameter, 3 mm in thickness) with the mold temperature adjusted to 140 ° C. The material of Comparative Example 1 had poor processability when produced with a twin-screw extruder, and pellets could not be obtained.

[0050] Example 8 Pellets were prepared in the same manner as above, and the obtained pellets were supplied to an injection molding machine (SE-75D-HP) manufactured by Sumitomo Heavy Industries, Ltd., whose cylinder temperature was set to 310°C. Then, injection molding was carried out using a molding die (a molded article having annular friction materials with an inner diameter of 45 mm and an outer diameter of 60 mm on both sides of a disc-shaped back plate with an outer diameter of 60 mm) whose die temperature was controlled to 140°C, and the friction material and back plate were molded together to obtain a friction member.

[0051] <Evaluation>

[0052] (1) Evaluation of Friction Coefficient A 10 mm wide and 10 mm long hole was drilled in the center of the friction member obtained in each Example and Comparative Example to prepare a test specimen. The obtained test specimen was sandwiched between two S-45C annular plates with an outer diameter of 70 mm, an inner diameter of 35 mm, and a thickness of 1 mm, and pressed at 0.1 MPa using a clamp to prepare a test member. In accordance with "5.4 Torque Test" of JIS B 1404-2:2005 "Electromagnetic Clutches and Electromagnetic Brakes - Part 2: Test Methods," a rotational torque was gradually applied through the hole in the test member, and the torque just before the test member rotated was measured as static friction torque, and the torque after rotation was measured as kinetic friction torque. The maximum static friction coefficient, kinetic friction coefficient, and the difference between the maximum static friction coefficient and the kinetic friction coefficient were calculated from each torque value.

[0053]

[0054] The blending ratios of the blending components in Table 1 were as follows: A-1: ​​PPS resin, linear type, melt viscosity (V6) 7 Pa·s A-2: PPS resin, linear type, melt viscosity (V6) 15 Pa·s A-3: PPS resin, linear type, melt viscosity (V6) 30 Pa·s A-4: PPS resin, linear type, melt viscosity (V6) 50 Pa·s B-1: Glass fiber, "T-717H" manufactured by Nippon Electric Glass Co., Ltd. B-2: Calcium carbonate, "Calcium Carbonate Grade 1" manufactured by Sankyo Flour Milling Co., Ltd. C-1: Graphite, "CNP15" manufactured by Ito Graphite Co., Ltd. D-1: Thermoplastic elastomer, ethylene-glycidyl methacrylate-methyl acrylate copolymer, "Bondfast 7L" manufactured by Sumitomo Chemical Co., Ltd. E-1: SUS304 E-2: A5052

[0055] - Production of PPS Resin <PPS Resin A-1> 35.839 kg (244 mol) of p-dichlorobenzene (hereinafter abbreviated as DCB), 4.332 kg (44 mol) of NMP, 27.300 kg of a 47.23 mass% NaSH aqueous solution (230 mol as NaSH), and 18.321 kg of a 49.21 mass% NaOH aqueous solution (225 mol as NaOH) were charged into a 150 L autoclave equipped with a pressure gauge, thermometer, condenser, decanter, and rectification column, and the temperature was raised to 173 ° C. over 5 hours under a nitrogen atmosphere with stirring. 26.760 kg of water was distilled off, and the kettle was then sealed. The DCB distilled by azeotropy during dehydration was separated using a decanter and returned to the kettle as needed. After completion of dehydration, the anhydrous sodium sulfide composition was dispersed in the DCB in the kettle. After the dehydration step was completed, the internal temperature was cooled to 160°C, 45.440 kg (458 mol) of NMP was charged, and the temperature was raised to 185°C. When the pressure reached 0.00 MPa, the valve connecting the distillation column was opened, and the internal temperature was raised to 200°C over 1 hour. During this time, the cooling and valve opening were controlled so that the outlet temperature of the distillation column was 110°C or less. The distilled mixed vapor of DCB and water was condensed in a condenser and separated in a decanter, and the DCB was returned to the kettle. The amount of distilled water was 180 g. The internal temperature was raised from 200°C to 230°C over 3 hours, stirred for 1 hour, and then raised to 250°C and stirred for 1 hour. After the reaction was completed, the bottom valve of the autoclave was opened and the mixture was flushed into a 150L vacuum agitator with an agitator blade to remove the NMP. Subsequently, the mixture was stirred under reduced pressure at 150 ° C for 4 hours to thoroughly remove the NMP, resulting in a mixture of powdered PPS resin and salts. 90 kg of 70 ° C ion-exchanged water was added to 30 kg of the obtained crude PPS mixture, stirred for 30 minutes, and then filtered. 90 kg of 70 ° C ion-exchanged water was added to the filtered cake for cake washing. Furthermore, the obtained hydrous cake and 60 kg of ion-exchanged water were charged into a 100L autoclave with an agitator blade, heated to 230 ° C over 2 hours with stirring, stirred for 30 minutes, extracted, and cooled to room temperature. The entire mixture obtained was filtered, and 90 kg of 70 ° C ion-exchanged water was added to the filtered cake for cake washing. This was then dried at 120 ° C for 4 hours to obtain a white powdered PPS resin.

[0056] <PPS Resin A-2> This was produced in the same manner as A-1, except that 34.824 kg (237 mol) of p-dichlorobenzene (p-DCB) was used.

[0057] <PPS Resin A-3> This was produced in the same manner as A-1, except that 33.810 kg (230 mol) of p-dichlorobenzene (p-DCB) was used.

[0058] <PPS Resin A-4> This was produced in the same manner as A-1, except that 33.472 kg (228 mol) of p-dichlorobenzene (p-DCB) was used.

[0059] Table 1 shows that the friction members of the examples have a friction material made of a thermoplastic resin composition and are excellent in maximum static friction coefficient and dynamic friction coefficient. Comparative Example 1, in which the melt viscosity of the thermoplastic resin was too high, had poor processability and it was difficult to manufacture the resin composition. Comparative Example 2, in which the blending amount of the thermoplastic resin was too high, had a large difference between the maximum static friction coefficient and the dynamic friction coefficient, and the friction behavior of the friction member was unstable and prone to vibration.

Claims

1. A method for manufacturing a friction member comprising at least a friction material and a backing plate supporting the friction material, comprising a step of melt molding a resin composition at or above the softening flow temperature of a thermoplastic resin (A) to form the friction material and the backing plate in the same molding cycle, wherein the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa·s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition. (Note that the melt viscosity (V6) represents the melt viscosity measured using a flow tester after holding the temperature at the softening flow temperature of the thermoplastic resin (A) + 20°C for 6 minutes under a load of 1.96 MPa and using an orifice with an orifice length / orifice diameter ratio of 10 / 1.) 2. A method for producing a friction member comprising at least a friction material and a backing plate supporting the friction material, comprising the steps of melt-molding a resin composition into a mold into which the backing plate is inserted at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A) to form a friction material, wherein the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa·s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

3. The method for producing a friction member according to claim 1 or 2, wherein the thermoplastic resin (A) is at least one selected from the group consisting of polybutylene terephthalate, polyamide 6T, polyamide 9T, polyamide 10T, polyamide MXD6, and polyarylene sulfide resins.

4. The method for producing a friction member according to claim 1 or 2, wherein the resin composition further comprises a solid lubricant (C) blended therein.

5. The method for producing a friction member according to claim 1 or 2, wherein the resin composition further comprises an organic filler (D).

6. The method for producing a friction member according to claim 2, wherein the back plate is at least one member selected from the group consisting of a resin member, a metal member and a ceramic member.

7. A friction member comprising at least a friction material and a backing plate supporting the friction material, wherein the friction material and the backing plate are formed by melt molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the resin composition contains, as essential components, a thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa·s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B), and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

8. A friction member comprising at least a friction material and a backing plate supporting the friction material, wherein the friction material is formed by melt molding a resin composition at a temperature equal to or higher than the softening flow temperature of a thermoplastic resin (A), the backing plate being at least one member selected from the group consisting of metal members and ceramic members, the resin composition comprising thermoplastic resin (A) having a melt viscosity (V6) of 30 Pa·s or less and a flow softening temperature of 130°C or more, and an inorganic filler (B) as essential components, and the amount of the thermoplastic resin (A) is 50 parts by mass or less per 100 parts by mass of the resin composition.

9. The friction member according to claim 6 or 7, wherein the thermoplastic resin (A) is at least one selected from the group consisting of polybutylene terephthalate, polyamide 6T, polyamide 9T, polyamide 10T, polyamide MXD6, and polyarylene sulfide resins.

10. The friction member according to claim 6 or 7, wherein the resin composition further contains a solid lubricant (C).

11. The friction member according to claim 6 or 7, wherein the resin composition further comprises an organic filler (D).

12. A method of using the friction member according to claim 6 or 7 as a braking part.

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