Resin composition for sliding, sliding member for wet lubrication, and retainer for bearing

Abstract

To provide a resin composition for sliding that, when applied to a sliding member, can enhance rigidity, impact resistance, and durability under high-speed sliding conditions in a wet lubrication mode.SOLUTION: A resin composition for sliding includes a polyphenylene sulfide resin (A), a melt-processable fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and a carbon fiber (D) having an average fiber length of 0.1 mm to 10 mm. The melt-processable fluororesin (B) and the olefin resin (C) have different reactive functional groups.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sliding resin composition containing polyphenylene sulfide resin, a sliding member for wet lubrication using the sliding resin composition, and a bearing cage.

Background Art

[0002] In recent years, the fields of use of synthetic resin bearings have expanded, and in particular, the performance required for bearing cages, such as exhibiting good friction and wear characteristics in a high-temperature atmosphere, has also increased. For example, in bearing cages used around engines and in transmissions, since they are close to heat sources, strength at high temperatures is required, and furthermore, slidability due to high-speed rotation and chemical resistance to oils and the like are required.

[0003] In rolling bearings such as tapered roller bearings, synthetic resin bearing cages may be used for the purpose of weight reduction, low torque, low wear, etc. As such a synthetic resin bearing cage, a molded body of a resin composition in which glass fiber is blended as a reinforcing material in a polyamide resin (such as polyamide 46 and polyamide 66) having excellent heat resistance is widely used.

[0004] In addition, although polyphenylene sulfide resin is inferior in toughness such as impact strength compared to polyamide resin, it is superior in heat resistance and chemical resistance to polyamide resin. Therefore, bearing cages using polyphenylene sulfide resin as a resin component are also being considered (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, a bearing cage provided with a sliding member made of a molded article of a resin composition containing a polyphenylene sulfide resin, as in Patent Document 1, may be damaged such as cracked when it is roughly handled or subjected to a large impact during bearing use. Further, since the bearing cage has not yet sufficient seizure life under high-speed sliding conditions of a lubrication method, a sliding member having more excellent durability is required.

[0007] The present invention has been made in view of the above circumstances, and when used for a sliding member, it is possible to improve rigidity, impact resistance, and durability under high-speed sliding conditions of a wet lubrication method. An object is to provide a sliding resin composition, a wet lubrication sliding member which is a molded article of the sliding resin composition, and a bearing cage using the wet lubrication sliding member.

Means for Solving the Problems

[0008] The present invention provides a sliding resin composition having the following configuration, a wet lubrication sliding member which is a molded article of the sliding resin composition, and a bearing cage using the wet lubrication sliding member.

[0009] Item 1 A sliding resin composition comprising a polyphenylene sulfide resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fibers (D) having an average fiber length of 0.1 mm to 10 mm, wherein the molten fluororesin (B) and the olefin resin (C) have different reactive functional groups.

[0010] Item 2 The sliding resin composition according to Item 1, further comprising inorganic fibers (E) having an average fiber length of 1 μm to 100 μm.

[0011] Item 3 The sliding resin composition according to Item 2, wherein the inorganic fibers (E) are at least one of potassium titanate fibers and wollastonite fibers.

[0012] Item 4. The sliding resin composition according to any one of Items 1 to 3, wherein the reactive functional group of the molten fluororesin (B) is an acidic group or an acid anhydride group.

[0013] Item 5. The sliding resin composition according to any one of Items 1 to 4, wherein the melt flow rate (MFR) of the molten fluororesin (B) at 297 °C and 5 kg load is 0.5 g / 10 min to 200 g / 10 min.

[0014] Item 6. The sliding resin composition according to any one of Items 1 to 5, wherein the reactive functional group of the olefin resin (C) is an epoxy group.

[0015] Item 7. The sliding resin composition according to any one of Items 1 to 6, wherein the melt flow rate (MFR) of the olefin resin (C) at 190 °C and 2.16 kg load is 0.5 g / 10 min to 500 g / 10 min.

[0016] Item 8. The sliding resin composition according to any one of Items 1 to 7, wherein the content of the carbon fiber (D) is 10% by mass to 40% by mass based on 100% by mass of the total amount of the sliding resin composition.

[0017] Item 9. The sliding resin composition according to any one of Items 1 to 8, wherein the tensile fracture strain measured in accordance with JIS K7161 of the sliding resin composition is less than 5%.

[0018] Item 10. A sliding member for wet lubrication, which is a molded body of the sliding resin composition according to any one of Items 1 to 9.

[0019] Item 11. A bearing cage that constitutes a rolling bearing together with an inner ring, an outer ring, and rolling elements, and rotatably holds the rolling elements, the bearing cage comprising the sliding member for wet lubrication according to Item 10.

Advantages of the Invention

[0020] According to the present invention, there can be provided a sliding resin composition that can improve rigidity, impact resistance, and durability under high-speed sliding conditions of a wet lubrication method when used for a sliding member, a wet lubrication sliding member that is a molded body of the sliding resin composition, and a bearing retainer using the wet lubrication sliding member.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, an example of a preferred embodiment in which the present invention is implemented will be described. However, the following embodiments are merely illustrative. The present invention is not limited to the following embodiments at all.

[0022] The sliding resin composition according to the present invention is a sliding resin composition used for a wet lubrication sliding member (hereinafter, may be simply referred to as a "sliding member") that slides under wet lubrication using a grease lubricant or an oil lubricant, and preferably is a sliding resin composition used for a sliding member that slides under wet lubrication using an oil lubricant. Examples of the oil lubricant include lubricating oils such as mineral oils such as engine oil, spindle oil, turbine oil, machine oil, cylinder oil, and gear oil; vegetable oils such as castor oil; animal oils such as whale oil; and synthetic oils such as silicone. These oil lubricants may be used alone or in combination of two or more.

[0023] The sliding resin composition is a resin composition containing polyphenylene sulfide resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fiber (D) having an average fiber length of 0.1 mm to 10 mm. Further, the molten fluororesin (B) and the olefin resin (C) have different reactive functional groups.

[0024] In the present specification, a member formed by molding a resin composition containing polyphenylene sulfide resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fiber (D) with an average fiber length of 0.1 mm to 10 mm is also referred to as a "sliding member". The "sliding member" may be manufactured by a general molding method such as injection molding, or may be manufactured by cutting or other processing methods.

[0025] The sliding resin composition of the present invention contains polyphenylene sulfide resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fiber (D) with an average fiber length of 0.1 mm to 10 mm. Since the molten fluororesin (B) and the olefin resin (C) have different reactive functional groups, when used for a sliding member, the rigidity, impact resistance, and durability under high-speed sliding conditions of the wet lubrication method can be improved. Further, since the sliding member, which is a molded body of such a sliding resin composition, has excellent sliding characteristics, it can be used for various applications without coating the sliding surface of the sliding member. Further, a bearing retainer constituted by such a sliding member is excellent in heat resistance and chemical resistance under high-speed sliding conditions of the wet lubrication method, and can further extend the seizure life even under severe conditions of high temperature and high-speed rotation.

[0026] In the sliding resin composition of the present invention, the mass ratio ((B)+(C)) / (A) of the total amount of the molten fluororesin (B) and the olefin resin (C) to the polyphenylene sulfide resin (A) is preferably 0.01 to 0.30, more preferably 0.05 to 0.30, and even more preferably 0.10 to 0.30. In this case, the rigidity, impact resistance, and durability of the obtained sliding member under high-speed sliding conditions of the wet lubrication method can be further improved.

[0027] In the sliding resin composition of the present invention, the mass ratio ((C) / (B)) of the olefin resin (C) to the molten fluororesin (B) is preferably 0.05 to 1. In this case, the rigidity, impact resistance, and durability under high-speed sliding conditions of the wet lubrication method of the obtained sliding member can be further improved.

[0028] Further, in the sliding resin composition of the present invention, the tensile fracture strain measured in accordance with JIS K7161 is preferably less than 5%, more preferably 4.5% or less. In this case, in the obtained sliding member, the rigidity can be further improved, and for example, a high flexural modulus that can withstand heat generation and deformation due to high-speed rotation can be obtained. Further, from the viewpoint of further improving the toughness of the obtained sliding member, the tensile fracture strain is preferably 0.1% or more, more preferably 0.5% or more.

[0029] Hereinafter, each component of the sliding resin composition of the present invention (hereinafter, may be simply referred to as "resin composition") will be described in more detail.

[0030] <Resin Composition> The resin composition of the present invention contains polyphenylene sulfide resin (A), molten fluororesin (B) having a reactive functional group, olefin resin (C) having a reactive functional group, and carbon fiber (D) having an average fiber length of 0.1 mm to 10 mm, and may further contain inorganic fiber (E) and other additives as required.

[0031] (Polyphenylene Sulfide Resin (A)) As the resin component in the resin composition of the present invention, polyphenylene sulfide resin (A) excellent in heat resistance and chemical resistance is used as the base resin. Further, the polyphenylene sulfide resin (A) has low water absorption and little swelling due to water absorption, and thus is also excellent in dimensional stability. The polyphenylene sulfide resin (A) includes a linear (straight-chain) type, a crosslinked (branched) type, and a semi-crosslinked (mixed type of straight-chain and branched) type. In the present invention, it can be used without being limited to these molecular structures and the like. Furthermore, as the polyphenylene sulfide resin (A), polymers having two or more types of molecular structures and molecular weights can be mixed and used. Among them, it is preferable to use a linear (straight-chain) polyphenylene sulfide resin (A). In addition, the polyphenylene sulfide resin (A) (hereinafter, may be referred to as "PPS resin") preferably has a molecular weight that enables injection molding even when containing inorganic fibers (E) in consideration of productivity.

[0032] The melt flow rate of the PPS resin (hereinafter, may be referred to as "MFR") is not particularly limited as long as melt kneading is possible. Since the molecular weight and the melt viscosity are correlated, the MFR can be used as an index of the molecular weight of the PPS resin. The MFR of the PPS resin measured under the conditions of 315 °C and a load of 5 kg is preferably 700 g / 10 min or less, more preferably 400 g / 10 min or less, still more preferably 350 g / 10 min or less, and particularly preferably 300 g / 10 min or less. In addition, the lower limit value of the MFR of the PPS resin is not particularly limited, but from the viewpoint of the melt viscosity, it is preferably 1 g / 10 min or more, more preferably 10 g / 10 min or more, still more preferably 15 g / 10 min or more, and particularly preferably 50 g / 10 min or more. By setting the MFR of the PPS resin within the above range, it is difficult to impair the moldability of the resin composition, and the wear amount during sliding in the obtained sliding member can be further reduced. The MFR of the PPS resin can be measured in accordance with JIS K7210.

[0033] The PPS resin used in the present invention is preferably a polymer containing, from the viewpoint of further improving heat resistance, crystallinity, and moldability, a repeating unit represented by the following formula (1) having a linear (straight-chain) molecular structure, preferably in an amount of 70 mol% or more, more preferably 90 mol% or more.

[0034]

Chemical formula

[0035] Further, in the PPS resin used in the present invention, less than 30 mol%, more preferably less than 10 mol% of the repeating unit may be composed of repeating units represented by the following formulas (2) to (8) and the like.

[0036]

Chemical formula

[0037] The PPS resin can be produced by conventionally known methods such as the method for obtaining a polymer with a relatively low molecular weight described in Japanese Patent Publication No. Sho 45-3368 and the method for obtaining a polymer with a relatively high molecular weight described in Japanese Patent Publication No. Sho 52-12240 and Japanese Unexamined Patent Publication No. Sho 61-7332. The PPS resin obtained by the above method may be used as it is, or may be used after crosslinking / higher molecular weight by heating in air, heat treatment in an inert gas atmosphere such as nitrogen or under reduced pressure, or washing with an organic solvent, hot water, an aqueous acid solution, etc.

[0038] The shape of the PPS resin is not particularly limited as long as melt kneading is possible, and it may be in any shape such as powder, granule, or pellet.

[0039] The content of the PPS resin in the resin composition of the present invention is preferably 30% by mass to 80% by mass, more preferably 35% by mass to 74% by mass, and even more preferably 40% by mass to 71% by mass based on 100% by mass of the total amount of the resin composition.

[0040] (Melt fluororesin (B)) The melt fluororesin (B) used in the resin composition of the present invention refers to a fluororesin to which molding means involving heat melting such as an extrusion molding method or an injection molding method performed on a general thermoplastic resin can be applied.

[0041] The structure of the melt fluororesin (B) used in the present invention is not particularly limited, but it is preferably composed of at least one kind of fluoroolefin. Examples of the melt fluororesin (B) include homopolymers such as chlorotrifluoroethylene, and copolymers of tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl ether), vinylidene fluoride, vinyl fluoride, and non-fluorine ethylenic monomers such as ethylene, propylene, butene, and alkyl vinyl ethers that do not contain fluorine. These melt fluororesins (B) may be used alone or in combination of two or more.

[0042] Specifically, examples of the melt fluororesin (B) include ethylene-tetrafluoroethylene copolymer (hereinafter sometimes referred to as "ETFE"), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (hereinafter sometimes referred to as "PFA"), tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter sometimes referred to as "FEP"), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride (hereinafter sometimes referred to as "PVDF"), polychlorotrifluoroethylene (hereinafter sometimes referred to as "PCTFE"), and the like. These melt fluororesins (B) may be used alone or in combination of two or more. Among them, from the viewpoint of further improving the melt moldability, the melt fluororesin (B) is preferably ETFE, PFA, FEP, or PVDF, and more preferably ETFE, PFA, or FEP.

[0043] The molten fluororesin (B) used in the present invention contains reactive functional groups. Therefore, the molten fluororesin (B) can more easily form intermolecular bonds with PPS resin or olefin resin (C).

[0044] The reactive functional groups are not particularly limited, and examples thereof include vinyl group, acidic groups such as carboxy group, acid anhydride group, ester group, aldehyde group, carbonyldioxy group, halocarbonyl group, alkoxycarbonyl group, amino group, hydroxyl group, styryl group, methacryl group, acrylic group, ureido group, mercapto group, sulfide group, isocyanate group, or hydrolyzable silyl group. Among them, the reactive functional group is preferably a hydroxyl group, epoxy group, acidic group (carboxy group), amino group, acid anhydride group, or isocyanate group, and more preferably an acidic group (carboxy group) or acid anhydride group. These reactive functional groups may be used alone or in combination of two or more.

[0045] Examples of the method for introducing reactive functional groups into the molten fluororesin include a method of blending a compound or resin that is compatible with the molten fluororesin and contains a functional group; a method of copolymerizing a polymerizable monomer containing a functional group or a functional group convertible to a functional group into the main chain, side chain, or terminal when polymerizing the molten fluororesin; a method of using an initiator containing a functional group or a functional group convertible to a functional group when polymerizing the molten fluororesin; a method of reacting the molten fluororesin with a polymerizable monomer containing a functional group or a functional group convertible to a functional group in the presence of a radical generator; a method of modifying the molten fluororesin by techniques such as oxidation and thermal decomposition. Among them, as a method for introducing reactive functional groups into the molten fluororesin, a method of copolymerizing a polymerizable monomer containing a functional group or a functional group convertible to a functional group into the main chain, side chain, or terminal when polymerizing the molten fluororesin, or a method of reacting the molten fluororesin with a polymerizable monomer containing a functional group or a functional group convertible to a functional group in the presence of a radical generator is preferable from the viewpoints of quality, cost, and control of the introduction amount.

[0046] The polymerizable monomer containing a functional group is not particularly limited. For example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, crotonic acid, hymic acid, acid anhydrides thereof, glycidyl acrylate, glycidyl methacrylate, glycidyl ethyl acrylate, glycidyl itaconate, vinyl acetate, vinyl propionate, vinyltrimethoxysilane, vinyltriethoxysilane, or γ-methacryloxypropyltrimethoxysilane, etc. may be mentioned. These polymerizable monomers may be used alone or in combination of two or more.

[0047] From the viewpoint of further promoting the reaction with the PPS resin or the olefin resin (C), the amount of the reactive functional group contained in the molten fluororesin (B) is preferably 0.01 mol% or more, more preferably 0.05 mol% or more, and even more preferably 0.1 mol% or more, based on 1 mol% of the molten fluororesin (B). The upper limit value of the amount of the reactive functional group is not particularly limited as long as the original properties of the molten fluororesin (B) are not impaired. However, considering the deterioration of the fluidity of the molten fluororesin (B), etc., it is preferably 10 mol% or less, more preferably 3 mol% or less, even more preferably 2 mol% or less, and particularly preferably 1 mol% or less.

[0048] The melting point of the molten fluororesin (B) used in the present invention is preferably 340 °C or lower, more preferably 300 °C or lower, and even more preferably 280 °C or lower. The lower limit value of the melting point of the molten fluororesin (B) is not particularly limited. However, from the viewpoint of further improving the heat resistance of the molten fluororesin at the processing temperature of the PPS resin, it is preferably 150 °C or higher, and more preferably 190 °C or higher. On the other hand, when the melting point of the molten fluororesin (B) exceeds the above upper limit value, the temperature for melt-kneading the resin composition becomes higher, so there is a risk that the PPS resin may deteriorate or the mechanical properties, etc. after molding of the resin composition may decrease.

[0049] The MFR of the molten fluororesin (B) used in the present invention at 297°C and a load of 5 kg is preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, preferably 200 g / 10 min or less, more preferably less than 200 g / 10 min, and even more preferably 100 g / 10 min or less. When the MFR of the molten fluororesin (B) is within the above range, good fluidity can be imparted to the molten fluororesin (B) during the melting of the PPS resin, and the compatibility between the molten fluororesin (B) and the PPS resin or the olefin resin (C) can be further enhanced. In this case, the rigidity, impact resistance, and durability of the obtained sliding member under high-speed sliding conditions of the wet lubrication method can be further improved.

[0050] When the MFR of the molten fluororesin (B) is less than the above lower limit value, not only is the fluidity during the melting of the PPS resin likely to be impaired, but also problems of poor appearance due to aggregation of the molten fluororesin (B) are likely to occur. When the MFR of the molten fluororesin (B) is greater than the above upper limit value, not only is the compatibility between the molten fluororesin (B) and the PPS resin or the olefin resin (C) during the melting of the PPS resin likely to be impaired, but also problems of layer separation of the molten fluororesin (B) during the molding of the resin composition are likely to occur. In addition, since the molecular weight of the molten fluororesin (B) becomes small, decomposition gas may be generated.

[0051] The MFR of the molten fluororesin (B) can be measured in accordance with JIS K7210. The temperature for measuring the MFR is 297°C, and the load is 5 kg. Note that the general load for measuring the MFR is 2.16 kg, but in this measurement, it is set to 5 kg. In the resin composition based on the PPS resin, a large shear force is applied to the molten fluororesin (B) during its melting, so the MFR under a high load is measured in consideration of this point.

[0052] The content of the molten fluororesin (B) in the resin composition of the present invention is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and even more preferably 2% by mass to 20% by mass based on 100% by mass of the total amount of the resin composition.

[0053] When the content of the molten fluororesin (B) is less than the above lower limit value, it tends to be difficult to impart the desired slidability and rigidity to the resulting sliding member. When the content of the molten fluororesin (B) exceeds the above upper limit value, the strength of the resin composition decreases, and it tends to be difficult to maintain the shape of the resulting sliding member. Further, when two or more kinds of molten fluororesins (B) are used in combination, it is more effective in imparting the characteristics of slidability and rigidity to the resulting sliding member.

[0054] (Olefin resin (C)) The olefin resin (C) used in the resin composition of the present invention can impart excellent impact resistance to the molded article of the resin composition.

[0055] Examples of the olefin resin (C) include homopolymers such as ethylene, propylene, and methylpentene; copolymers using two or more of α-olefins such as ethylene, propylene, methylpentene, 1-butene, 1-hexene, and 1-octene, and cycloolefins; and copolymers of one or more of α-olefins such as ethylene, propylene, methylpentene, 1-butene, 1-hexene, and 1-octene with vinyl acetate, ethyl acrylate, methyl acrylate, glycidyl methacrylate, butyl acrylate, methyl acrylate, styrene, etc. More specifically, examples of the olefin resin (C) include polyethylene, polypropylene, polymethylpentene, ethylene-butene copolymer, ethylene-propylene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-styrene copolymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, ethylene-ethyl acrylate-glycidyl methacrylate copolymer, or ethylene-vinyl acetate-glycidyl methacrylate copolymer.

[0056] Among them, as the olefin resin (C), an olefin-based elastomer such as an ethylene-butene copolymer, an ethylene-propylene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer, an ethylene-vinyl acetate copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-glycidyl methacrylate copolymer, an ethylene-butyl acrylate copolymer, an ethylene-methyl acrylate copolymer, an ethylene-styrene copolymer, an ethylene-methyl acrylate-glycidyl methacrylate copolymer, an ethylene-ethyl acrylate-glycidyl methacrylate copolymer, or an ethylene-vinyl acetate-glycidyl methacrylate copolymer is preferably used.

[0057] The olefin resin (C) used in the present invention has a reactive functional group. Therefore, the olefin resin (C) used in the present invention easily forms an intermolecular bond with the PPS resin or the molten fluororesin (B).

[0058] The reactive functional group in the olefin resin (C) is not particularly limited, and examples thereof include a vinyl group, an epoxy group, a glycidyl group, an ester group, an aldehyde group, a carbonyldioxy group, a halocarbonyl group, an alkoxycarbonyl group, an amino group, a hydroxyl group, a styryl group, a methacryl group, an acrylic group, a ureido group, a mercapto group, a sulfide group, an isocyanate group, or a hydrolyzable silyl group. Among them, the reactive functional group is preferably a hydroxyl group, an epoxy group, a glycidyl group, an acidic group (carboxy group), an amino group, or an isocyanate group, and more preferably an epoxy group or a glycidyl group. These reactive functional groups may be used alone or in combination of two or more.

[0059] As methods for introducing reactive functional groups into olefin resins, there are methods of blending a compound or resin that is compatible with the olefin resin and contains functional groups; methods of copolymerizing a polymerizable monomer that contains a functional group or a functional group convertible to a functional group in the main chain, side chain, or terminal when polymerizing the olefin resin; methods of using an initiator that contains a functional group or a functional group convertible to a functional group when polymerizing the olefin resin; methods of reacting an olefin resin with a polymerizable monomer that contains a functional group or a functional group convertible to a functional group in the presence of a radical generator; methods of modifying the olefin resin by techniques such as oxidation and thermal decomposition, and the like. Among these, methods of copolymerizing a polymerizable monomer that contains a functional group or a functional group convertible to a functional group in the main chain, side chain, or terminal when polymerizing the olefin resin, or methods of reacting an olefin resin with a polymerizable monomer that contains a functional group or a functional group convertible to a functional group in the presence of a radical generator are preferable from the viewpoints of quality, cost, and control of the introduction amount.

[0060] The polymerizable monomer containing a functional group is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, crotonic acid, hymic acid, acid anhydrides thereof, glycidyl acrylate, glycidyl methacrylate, glycidyl ethyl acrylate, glycidyl itaconate, vinyl acetate, vinyl propionate, vinyltrimethoxysilane, vinyltriethoxysilane, or γ-methacryloxypropyltrimethoxysilane, and the like.

[0061] The amount of the reactive functional group contained in the olefin resin (C) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 1% by mass or more, based on 100% by mass of the total amount of the olefin resin (C), from the viewpoint of facilitating the reaction with the PPS resin and the molten fluororesin (B). The upper limit of the amount of the reactive functional group contained in the olefin resin (C) is not particularly limited as long as the original properties of the olefin resin (C) are not impaired, but considering the deterioration of fluidity, etc., it is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0062] The melt flow rate of the olefin resin (C) (hereinafter, may be referred to as "MFR") is not particularly limited as long as melt kneading is possible, but the MFR measured under the conditions of 190 °C and a load of 2.16 kg is preferably 0.5 g / 10 min or more and preferably 500 g / 10 min or less. By setting the MFR value of the olefin resin (C) within the above range, good fluidity can be imparted to the olefin resin (C) during the melting of the PPS resin, and the compatibility between the olefin resin (C) and the PPS resin or the molten fluororesin (B) can be further enhanced. In this case, the rigidity, impact resistance, and durability of the obtained sliding member under high-speed sliding conditions of the wet lubrication method can be further improved. The MFR of the olefin resin (C) can be measured in accordance with JIS K7210.

[0063] The content of the olefin resin (C) is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and still more preferably 2% by mass to 20% by mass, based on 100% by mass of the total amount of the resin composition, from the viewpoint of achieving both impact resistance and toughness at a higher level. The olefin resin (C) can also be used in combination of two or more kinds.

[0064] When the content of the olefin resin (C) is less than the above lower limit value, the strength of the resin composition decreases, it becomes difficult to maintain the shape of the resulting sliding member, and durability under high-speed sliding conditions of the wet lubrication method may not be obtained. Further, when the content of the olefin resin (C) exceeds the above upper limit value, the impact resistance of the resulting sliding member may decrease.

[0065] (Carbon fiber (D)) As the carbon fiber (D) used in the resin composition of the present invention, for example, polyacrylonitrile (PAN)-based, pitch-based, cellulose-based, or carbon fibers grown by vapor phase growth using hydrocarbons, graphite fibers, etc. can be used. These carbon fibers (D) may be used alone or in combination of two or more. From the viewpoint of further improving the mechanical strength and slidability of the resulting sliding member, the carbon fiber (D) is preferably a polyacrylonitrile-based carbon fiber.

[0066] In the present invention, the average fiber length of the carbon fiber (D) is 0.1 mm or more, preferably 0.3 mm or more. By setting the average fiber length of the carbon fiber (D) to the above lower limit value or more, the flexural modulus (rigidity) of the resulting sliding member can be further improved. Further, from the viewpoint of further improving the moldability of the resin composition, the carbon fiber (D) is preferably a continuous fiber such as a long fiber or a milled fiber. Further, the average fiber length of the carbon fiber (D) is preferably 10 mm or less, more preferably 8 mm or less, and still more preferably 7.5 mm or less.

[0067] In the present invention, the average fiber diameter of the carbon fiber (D) is preferably 1 μm to 50 μm, more preferably 3 μm to 20 μm. When the average fiber diameter of the carbon fiber (D) is within the above range, even if the content of the carbon fiber (D) contained in the resin composition of the present invention is increased, a further decrease in the fluidity of the resin composition can be suppressed. Note that as long as the average fiber diameter of the carbon fiber (D) is within the above range, it may be in the form of a bundle of carbon fibers aggregated with a sizing agent or the like.

[0068] In the present invention, the tensile elastic modulus of carbon fiber (D) is preferably 190 GPa to 300 GPa, more preferably 230 GPa to 300 GPa. If the tensile elastic modulus of carbon fiber (D) is too small, the reinforcing effect of the sliding interface by carbon fiber (D) is small, excessive frictional powder is generated, and the friction coefficient of the obtained sliding member may become unstable. On the other hand, if the tensile elastic modulus of carbon fiber (D) is too large, there is a risk that the detached material on the sliding interface becomes a large resistance. The tensile elastic modulus of carbon fiber (D) indicates a value measured in accordance with Method A of JIS R7606 (2000).

[0069] The content of carbon fiber (D) is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less. When the content of carbon fiber (D) is within the above range, in the obtained sliding member, the performance related to rigidity such as flexural elastic modulus can be further enhanced, and the fluidity can be further enhanced. When the content of carbon fiber (D) is greater than the above upper limit value, in the obtained sliding member, the surface smoothness may deteriorate, and sufficient sliding characteristics (such as a low friction coefficient and suppression of sliding heat generation) and durability may not be obtained.

[0070] <Optional component of the resin composition> (Inorganic fiber (E)) The resin composition of the present invention may further contain inorganic fiber (E). The inorganic fiber (E) is not particularly limited, but from the viewpoint of further enhancing the sliding characteristics of the obtained sliding member, it is preferably an inorganic fiber having a Mohs hardness of 5 or less. The Mohs hardness is an index representing the hardness of a substance, and when minerals are rubbed against each other, the substance that is damaged is the one with a lower hardness. Examples of inorganic fibers having a Mohs hardness of 5 or less include inorganic fibers such as potassium titanate fiber, wollastonite fiber, zinc oxide fiber, basic magnesium sulfate fiber, alumina fiber, silicon carbide fiber, or boron fiber. These inorganic fibers may be used alone or in combination of two or more.

[0071] The inorganic fiber (E) is preferably a powder composed of fibrous particles. From the viewpoint of further enhancing the sliding characteristics of the obtained sliding member and further extending the seizure life even under severe conditions of high temperature and high-speed rotation, the average fiber length of the inorganic fiber (E) is preferably 100 μm or less, more preferably 1 μm to 100 μm, still more preferably 1 μm to 75 μm, even more preferably 3 μm to 50 μm, and particularly preferably 5 μm to 40 μm. The average aspect ratio of the inorganic fiber (E) is preferably 10 to 200, more preferably 10 to 100, still more preferably 10 to 50, and particularly preferably 10 to 40.

[0072] In the present invention, the fibrous particle means a particle in which, when the longest side of the rectangular parallelepiped with the smallest volume among the rectangular parallelepipeds circumscribing the particle (circumscribed rectangular parallelepiped) is defined as the major axis L, the next longest side is defined as the minor axis B, and the shortest side is defined as the thickness T (B > T), both L / B and L / T are 3 or more. The major axis L corresponds to the fiber length, and the minor axis B corresponds to the fiber diameter.

[0073] From the viewpoint of further enhancing the sliding characteristics of the obtained sliding member and further extending the seizure life even under severe conditions of high temperature and high-speed rotation, the inorganic fiber (E) is preferably at least one of potassium titanate fiber and wollastonite fiber, more preferably potassium titanate fiber or wollastonite fiber, and still more preferably potassium titanate fiber.

[0074] Potassium titanate fibers include, for example, single crystal fibers represented by the general formula K2O·nTiO2 (where n is an integer from 2 to 8) or the general formula K2O·nTiO2·1 / 2H2O (where n is an integer from 2 to 8). Specific examples of potassium titanate fibers include potassium 4-titanate fibers, potassium 6-titanate fibers, potassium 8-titanate fibers, etc., and mixtures thereof. The dimensions of the potassium titanate fibers are not particularly limited as long as they are within the range of the dimensions of the above-mentioned inorganic fibers (E). The average fiber length of the potassium titanate fibers is preferably 1 μm to 50 μm, more preferably 3 μm to 30 μm, and even more preferably 3 μm to 20 μm. The average fiber diameter of the potassium titanate fibers is preferably 0.01 μm to 1 μm, more preferably 0.05 μm to 0.8 μm, and even more preferably 0.1 μm to 0.7 μm. The average aspect ratio of the potassium titanate fibers is preferably 10 or more, more preferably 10 to 100, and even more preferably 15 to 35.

[0075] Wollastonite fibers are inorganic fibers composed of calcium metasilicate, and conventionally known ones can be widely used. The dimensions of the wollastonite fibers are not particularly limited as long as they are within the range of the dimensions of the above-mentioned inorganic fibers (E). The average fiber length of the wollastonite fibers is preferably 5 μm to 100 μm, more preferably 10 μm to 75 μm, and even more preferably 20 μm to 40 μm. The average fiber diameter of the wollastonite fibers is preferably 0.1 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 2 μm to 7 μm. The average aspect ratio of the wollastonite fibers is preferably 3 or more, more preferably 3 to 30, and even more preferably 3 to 15.

[0076] The average fiber length and average fiber diameter of the inorganic fiber (E) etc. can be measured by observation with a scanning electron microscope, and the average aspect ratio (average fiber length / average fiber diameter) can be calculated from the average fiber length and average fiber diameter. The above-mentioned average fiber length and average fiber diameter can be obtained, for example, by photographing a plurality of inorganic fibers (E) with a scanning electron microscope, arbitrarily selecting 300 inorganic fibers (E) from the observation image, measuring their fiber lengths and fiber diameters, integrating all the fiber lengths and dividing by the number to obtain the average fiber length, and integrating all the fiber diameters and dividing by the number to obtain the average fiber diameter.

[0077] From the viewpoint of further improving the dispersibility of the inorganic fiber (E) in the resin composition and further improving the adhesion between the PPS resin and the inorganic fiber (E), a treatment layer composed of a surface treatment agent may be formed on the surface of the inorganic fiber (E).

[0078] The surface treatment agent is not particularly limited, and examples thereof include silane coupling agents and titanium coupling agents. Among these, the surface treatment agent is preferably a silane coupling agent, and more preferably an amino-based silane coupling agent, an epoxy-based silane coupling agent, or an alkyl-based silane coupling agent. The surface treatment agent may be used alone or in combination of two or more.

[0079] Examples of the amino-based silane coupling agent include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, and the like.

[0080] Examples of epoxy-based silane coupling agents include 3-glycidyloxypropyl(dimethoxy)methylsilane, 3-glycidyloxypropyltrimethoxysilane, diethoxy(3-glycidyloxypropyl)methylsilane, triethoxy(3-glycidyloxypropyl)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like.

[0081] Examples of alkyl-based silane coupling agents include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, and the like.

[0082] As a method for forming a treatment layer composed of a surface treatment agent on the surface of the inorganic fiber (E), a conventionally known surface treatment method can be used. Examples of the method for forming a treatment layer composed of a surface treatment agent include a wet method in which the surface treatment agent is dissolved in a solvent that promotes hydrolysis (e.g., water, alcohol, or a mixed solvent thereof) to form a solution, and the solution is sprayed onto the inorganic fiber (E).

[0083] The amount of the surface treatment agent for treating the surface of the inorganic fiber (E) is not particularly limited. In the case of the wet method, for example, a solution of the surface treatment agent may be sprayed so that the surface treatment agent is 0.1 part by mass to 20 parts by mass with respect to 100 parts by mass of the total amount of the inorganic fiber (E).

[0084] The content of the inorganic fiber (E) is preferably 0.5% by mass or more, more preferably 5% by mass or more, and preferably less than 20% by mass. In this case, the rigidity of the obtained sliding member can be further improved.

[0085] (Other additives) The resin composition of the present invention can contain other additives as long as its preferable physical properties are not impaired. Examples of the other additives include non-fibrous inorganic fillers such as calcium carbonate, mica, muscovite, sericite, illite, talc, kaolinite, montmorillonite, boehmite, smectite, vermiculite, palygorskite, pyrophyllite, halloysite, diatomaceous earth, titanium dioxide, potassium titanate, sodium titanate, potassium magnesium titanate, or lithium potassium titanate; metal particles such as aluminum flakes, metal fibers, metal oxide particles, graphite, expanded graphite, flaky graphite, graphene, carbon black, graphitized carbon black, etc. carbon particles, or conductive fillers such as carbon nanotubes; antistatic agents; antioxidants and heat stabilizers; ultraviolet absorbers; light stabilizers; weathering agents; lightfast agents; mold release agents; lubricants; fluidity improvers; plasticizers; impact resistance improvers; flame retardants; dripping inhibitors; nucleating agents; dispersants; vibration damping agents; neutralizing agents; antiblocking agents, and the like. These other additives may be used alone or in combination of two or more.

[0086] When the resin composition used in the present invention contains other additives, the blending amount thereof is not particularly limited as long as the preferable physical properties of the resulting sliding member are not impaired. The content of the other additives is, for example, 10% by mass or less, preferably 5% by mass or less, based on 100% by mass of the total amount of the resin composition.

[0087] <Method for producing resin composition> The resin composition of the present invention contains polyphenylene sulfide resin (A), molten fluororesin (B) having a reactive functional group, olefin resin (C) having a reactive functional group, and carbon fiber (D) having an average fiber length of 0.1 mm to 10 mm. Optionally, a mixture containing inorganic fiber (E) and other additives can be produced by mixing and heating by melt kneading or the like. For melt kneading, for example, a known melt kneading apparatus such as a twin screw extruder can be used.

[0088] Specifically, the resin composition can be produced by the following methods: (1) preliminarily mixing each component with a mixer (such as a tumbler or a Henschel mixer), melt-kneading with a melt-kneading apparatus, and pelletizing with a pelletizing means (such as a pelletizer); (2) preparing a masterbatch of the desired components, mixing other components if necessary, and melt-kneading with a melt-kneading apparatus to pelletize; (3) supplying each component to a melt-kneading apparatus and pelletizing, etc.

[0089] The processing temperature in melt-kneading is not particularly limited as long as it is a temperature at which the polyphenylene sulfide resin (A) can melt. Usually, the cylinder temperature of the melt-kneading apparatus used for melt-kneading is adjusted within the range where the polyphenylene sulfide resin (A) can melt. In this way, a resin composition that exhibits the desired effects is produced.

[0090] <Method for manufacturing and use of sliding member for wet lubrication> The sliding member for wet lubrication of the present invention is a molded body of the resin composition of the present invention. The above resin composition can be molded into various molded products by known resin molding methods such as injection molding, insert molding, compression molding, blow molding, inflation molding, etc., according to the type, use, shape, etc. of the target molded body. Among them, the molding method of the resin composition is preferably injection molding or insert molding. Also, the molding method of the resin composition may adopt a method combining the above-mentioned molding methods.

[0091] The sliding member for wet lubrication of the present invention is excellent in rigidity, impact resistance, and durability under high-speed sliding conditions of the wet lubrication system. Also, the sliding member for wet lubrication of the present invention is excellent in heat resistance and chemical resistance under high-speed sliding conditions of the wet lubrication system, and can further extend the seizure life even under severe conditions of high temperature and high-speed rotation.

[0092] Therefore, the sliding member for wet lubrication of the present invention can be suitably used as a member for manufacturing a cage for a bearing. The sliding member for wet lubrication of the present invention, for example, constitutes a rolling bearing together with an inner ring, an outer ring, and rolling elements, and is used in a high-speed rotation (sliding) region that rotatably holds the rolling elements, and is suitably used for manufacturing a cage for a bearing for an automatic transmission and sliding parts that constitute a rolling bearing provided with the cage for a bearing.

[0093] The lubrication method of the sliding member for wet lubrication of the present invention is roughly classified into grease lubrication in which the member is lubricated by a grease lubricant enclosed in the bearing internal space (the annular space between the inner ring and the outer ring) and oil lubrication in which the member is lubricated by an oil lubricant successively supplied from the outside of the bearing to the bearing internal space. However, since it is necessary to improve the lubrication and cooling efficiency, the lubrication method of the sliding member for wet lubrication of the present invention is preferably an oil lubrication method. Furthermore, the oil lubrication method is roughly classified into jet lubrication, under-race lubrication, air-oil lubrication, oil mist lubrication, etc. However, since the supply amount of the oil lubricant per unit time is extremely small and the usage amount of the oil lubricant (the cost required for lubrication) can be suppressed, the oil lubrication method applied to the sliding member for wet lubrication of the present invention is preferably an air-oil lubrication or oil mist lubrication method.

[0094] <Cage for a bearing> The cage for a bearing of the present invention is a cage that constitutes a rolling bearing together with an inner ring, an outer ring, and rolling elements and rotatably holds the rolling elements. The cage for a bearing of the present invention includes the above-described sliding member for wet lubrication.

[0095] The sliding member for wet lubrication of the present invention is excellent in mechanical strength, particularly rigidity. When a bearing cage for a shaft is formed with this as a constituent member and the guiding type of the bearing cage for a shaft is rolling element guiding, even when the inner ring or the outer ring rotates at high speed under a lubrication method in which the supply amount of lubricating oil into the bearing is small, such as air-oil lubrication or oil mist lubrication, contact and sliding between the inner ring or the outer ring and the bearing cage for a shaft can be avoided. Thereby, it is possible to prevent malfunctions such as wear and seizure from occurring in the inner ring, the outer ring, and the bearing cage for a shaft as much as possible.

[0096] Combined with the above-described functions and effects, the rolling bearing provided with the bearing cage of the present invention can stably exhibit predetermined bearing performance over a long period of time and is highly reliable even when used under severe conditions where the supply amount of lubricating oil is small under high-speed sliding conditions of the wet lubrication method.

[0097] The bearing cage for a shaft provided with the sliding member for wet lubrication of the present invention is excellent in rigidity, impact resistance, and durability under high-speed sliding conditions of the wet lubrication method. According to the bearing cage for a shaft of the present invention, when the rolling bearing is rotated (slid) at high speed, the friction coefficient is small and sliding heat generation is suppressed. Further, the bearing cage for a shaft of the present invention is excellent in heat resistance and chemical resistance, and can further extend the seizure life. Furthermore, according to the bearing cage for a shaft of the present invention, reduction in deformation and breakage due to the centrifugal force of the rolling elements during high-speed sliding, and reduction in vibration and abnormal noise can be expected.

[0098] As another embodiment of the present invention, there is a rolling bearing for an automatic transmission including the above-described bearing cage as a component.

[0099] Among the components of the above-described rolling bearing, as the rolling elements, it is preferable to use balls, cylindrical rollers, or needle rollers, and it is more preferable to use needle rollers.

Example

[0100] Specific descriptions will be given below based on Examples and Comparative Examples. However, as long as the gist of the present invention is not impaired, it is not limited thereto. The raw materials used in the present Examples and Comparative Examples are specifically as follows.

[0101] <Raw material> (Polyphenylene sulfide (PPS) resin (A)) Polyphenylene sulfide (PPS) resin: melting point 280 °C, glass transition temperature: 90 °C, manufactured by Toray Industries, Inc., trade name "Torelina M2588", MFR: 300 g / 10 min (in accordance with JIS K7210, 315 °C, 5 kg load)

[0102] (Melt fluororesin (B)) Ethylene-tetrafluoroethylene copolymer containing acid anhydride group: maleic acid modified, MFR: 22 g / 10 min (in accordance with JIS K7210, 297 °C, 5 kg load), melting point 245 °C, amount of reactive functional group 0.4 mol%, specific gravity 1.78 g / cm 3 , manufactured by AGC Inc., trade name "Fluon AH-2000"

[0103] (Olefin resin (C)) Ethylene-glycidyl methacrylate copolymer 1: ethylene-glycidyl methacrylate copolymer, MFR: 3 g / 10 min (in accordance with JIS K7210, 190 °C, 2.16 kg load), melting point 105 °C, amount of reactive functional group: 6% by mass, specific gravity: 0.93 g / cm 3 , manufactured by Sumitomo Chemical Co., Ltd., trade name "Bondfast 2C" Ethylene-glycidyl methacrylate copolymer 2: ethylene-glycidyl methacrylate copolymer, MFR: 5 g / 10 min (in accordance with JIS K7210, 190 °C, 2.16 kg load), melting point 109 °C, amount of reactive functional group: 8% by mass, specific gravity: 0.94 g / cm 3 , manufactured by Arkema, trade name "Lotader AX8840" Ethylene-glycidyl methacrylate copolymer 3: ethylene-glycidyl methacrylate copolymer, MFR: 6 g / 10 min (in accordance with JIS K7210, 190 °C, 2.16 kg load), melting point 60 °C, amount of reactive functional group: 32% by mass, specific gravity: 0.95 g / cm3 , manufactured by Arkema, product name "Rotader AX8900" Ethylene-glycidyl methacrylate copolymer 4: Ethylene-glycidyl methacrylate copolymer, maleic acid modified (anhydride group-containing), MFR: 7 g / 10 min (in accordance with JIS K7210, 190 °C, 2.16 kg load), melting point 65 °C, amount of reactive functional groups: 1.3 mass%, specific gravity: 0.94 g / cm 3 , manufactured by Arkema, product name "Rotader AX4700"

[0104] (Carbon fiber (D)) Carbon fiber: Polyacrylonitrile (PAN)-based carbon fiber, tensile modulus of elasticity 300 GPa, average fiber length 200 μm, average fiber diameter 7 μm, manufactured by Nippon Polymer Industry Co., Ltd., product name: "CF EX1-LC-HS C6"

[0105] (Inorganic fiber (E)) Potassium titanate fiber: average fiber length 15 μm, average fiber diameter 0.5 μm, manufactured by Otsuka Chemical Co., Ltd., product name "Tismo D102" Note that the average fiber length, average fiber diameter, and aspect ratio of the potassium titanate fiber were determined from the average values of any 1000 measured by observation with a scanning electron microscope (SEM).

[0106] <Examples 1 to 7 and Comparative Examples 1 to 3> In each example and comparative example, the raw materials were melt-kneaded using a twin-screw extruder at the compounding ratios shown in Table 1 to produce pellets. The cylinder temperature of the twin-screw extruder was 300 °C. The obtained pellets were injection-molded to produce JIS test pieces and friction and wear test pieces (hollow cylinders with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm). The cylinder temperature of the injection molding machine was 320 °C, and the mold temperature was 130 °C.

[0107] <Evaluation> (Flexural strength, flexural modulus) For the fabricated JIS test specimens (bending test specimens), in accordance with JIS K7271, the flexural strength and flexural modulus were measured by a three-point bending test with a span of 60 mm using an autograph AG-5000 (manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0108] (Izod impact value (notched)) For the fabricated JIS test specimens, the Izod impact value (notched) was measured in accordance with JIS K7110. The results are shown in Table 1.

[0109] (Tensile fracture strain) For the fabricated JIS test specimens, in accordance with JIS K7161, the tensile fracture strain was measured using an autograph AG-5000 (manufactured by Shimadzu Corporation) with a span of 100 mm and a tensile speed of 10 mm / min.

[0110] (Limiting PV) For each of the JIS test specimens obtained above, ATF oil (manufactured by Toyota Motor Corporation, "T-IV") was applied, and in accordance with JIS K7218 Method A, using a Suzuki-type friction and wear tester (manufactured by Orientec Corporation), the test was conducted at a rotational speed of 3000 rpm (outer peripheral speed 4 m / s), with the mating material being SCM435C (carbon steel buff finish, φ8, 4 pieces (line contact)), an initial load of 40 N at room temperature, and pressurization in 10 N increments every hour. The maximum PV value at which abnormal wear or melting of the friction surface did not occur was determined as the limiting PV value. Here, V is the sliding speed (m / s) at 4 m / s, P is the Hertz stress (MPa), and the temperature is room temperature.

[0111]

Table 1

[0112] As is clear from Table 1, a resin composition containing polyphenylene sulfide (PPS) resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fiber (D) with an average fiber length of 0.1 to 10 mm, wherein the molten fluororesin (B) and the olefin resin (C) have different reactive functional groups. It can be seen that the molded articles (sliding members) of the sliding resin compositions of Examples 1 to 7 are excellent in mechanical properties (rigidity such as flexural strength and flexural modulus), and have an increased limiting PV (durability). Further, by comparing Example 1 and Example 7, it can be seen that an unexpected effect is achieved in that the limiting PV (durability) of the molded article (sliding member) is significantly increased by using carbon fiber (D) and potassium titanate fiber which is an inorganic fiber (E) in combination.

[0113] On the other hand, in Comparative Example 1 which is a molded article of a resin composition not containing the molten fluororesin (B) and the olefin resin (C) in the resin composition, Comparative Example 2 which is a molded article of a resin composition not containing the olefin resin (C), or a molded article of the resin composition of Comparative Example 3 in which the molten fluororesin (B) and the olefin resin (C) have the same reactive functional group, it can be seen that the limiting PV is not sufficiently increased.

[0114] Thus, the sliding resin composition of the present invention can improve rigidity, impact resistance, and durability under high-speed sliding conditions of a wet lubrication method when used for a sliding member. Further, a bearing retainer constituted by a wet lubrication sliding member which is a molded article of such a sliding resin composition is excellent in heat resistance and chemical resistance under high-speed sliding conditions of a wet lubrication method, and can further extend the seizure life even under severe conditions of high temperature and high-speed rotation.

Claims

1. A sliding resin composition comprising polyphenylene sulfide resin (A), a molten fluororesin (B) having a reactive functional group, an olefin resin (C) having a reactive functional group, and carbon fibers (D) having an average fiber length of 0.1 mm to 10 mm, wherein the molten fluororesin (B) and the olefin resin (C) have different reactive functional groups.

2. The sliding resin composition according to Claim 1, further comprising inorganic fibers (E) having an average fiber length of 1 μm to 100 μm.

3. The sliding resin composition according to Claim 2, wherein the inorganic fibers (E) are at least one of potassium titanate fibers and wollastonite fibers.

4. The sliding resin composition according to Claim 1 or Claim 2, wherein the reactive functional group of the molten fluororesin (B) is an acidic group or an acid anhydride group.

5. The sliding resin composition according to Claim 1 or Claim 2, wherein the melt flow rate (MFR) of the molten fluororesin (B) at 297 °C and 5 kg load is 0.5 g / 10 min to 200 g / 10 min.

6. The sliding resin composition according to Claim 1 or Claim 2, wherein the reactive functional group of the olefin resin (C) is an epoxy group.

7. The sliding resin composition according to Claim 1 or Claim 2, wherein the melt flow rate (MFR) of the olefin resin (C) at 190 °C and 2.16 kg load is 0.5 g / 10 min to 500 g / 10 min.

8. The sliding resin composition according to Claim 1 or Claim 2, wherein the content of the carbon fibers (D) is 10% by mass to 40% by mass based on 100% by mass of the total amount of the sliding resin composition.

9. The sliding resin composition according to Claim 1 or Claim 2, wherein the tensile fracture strain measured in accordance with JIS K7161 of the sliding resin composition is less than 5%.

10. A sliding member for wet lubrication, which is a molded body of the sliding resin composition according to Claim 1 or Claim 2.

11. A bearing cage that constitutes a rolling bearing together with an inner ring, an outer ring, and rolling elements, and rotatably holds the rolling elements, the bearing cage comprising the sliding member for wet lubrication according to Claim 10.

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