Sliding member

Abstract

A sliding member according to the present disclosure contains, in a sliding layer, a synthetic resin, a solid lubricant, and an additive. The synthetic resin is a polyimide, a polyamide imide, a polybenzimidazole, a polyphenyl sulfone, a polyether sulfone, a polyether ether ketone, or a combination thereof. The solid lubricant is a polytetrafluoroethylene, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, a tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof. The contained amount of the solid lubricant in the sliding layer is 5.0-40.0 vol.%. The additive is bentonite, smectite clay mineral, silica, a polyamide, or a combination thereof. The contained amount of the additive in the sliding layer is 0.1-9.0 vol.%.

Description

Sliding member

[0001] This application claims priority to Japanese Patent Application No. 2022-101433, filed on June 23, 2022, and incorporates by reference all of the contents of the above-mentioned Japanese application.

[0002] Wear resistance and heat resistance are required for sliding members provided in rotary devices and components, such as oil pumps that pump engine oil to various locations inside an engine. Cross-linked fluororesins have been disclosed as coating agents for rotors, which serve as sliding parts in such oil pumps. Prior art has proposed, for example, coating a substrate comprising the main body of a sliding member with a fluororesin irradiated with ionizing radiation (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2011-208802

[0004] A sliding member according to one aspect of the present disclosure is a sliding member including a sliding layer, the sliding layer containing a synthetic resin, a solid lubricant, and an additive, the synthetic resin being polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, or a combination thereof, the solid lubricant being polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof, the content of the solid lubricant in the sliding layer being 5.0 vol% or more and 40.0 vol% or less, the additive being bentonite, a smectite clay mineral, silica, polyamide, or a combination thereof, and the content of the additive in the sliding layer being 0.1 vol% or more and 9.0 vol% or less.

[0005] FIG. 1 is a schematic cross-sectional view showing a sliding member according to a first embodiment.

[0006] [Problem to be Solved by the Present Disclosure] In recent years, with the increasing demand for higher rotation speeds and improved fuel economy in internal combustion engines and the like, further improvements in the sliding properties of sliding members, such as wear resistance and abrasion resistance, are being demanded. In addition, because coating films using fluororesin paints as in conventional technology are relatively soft, metallic foreign matter such as iron powder is likely to penetrate and become embedded in the surface of the coating film. This poses a problem in that scratches, tears, etc. in the coating film can lead to an increase in the torque of rotary sliding members.

[0007] The present disclosure has been made in light of the above circumstances, and has an object to provide a sliding member that has high hardness, torque reduction effect, and excellent wear resistance.

[0008] [Effects of the Present Disclosure] A slide member according to one aspect of the present disclosure has high hardness, and is excellent in torque reduction effect and wear resistance.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] The present disclosure provides a sliding member: (1) a sliding member including a sliding layer, the sliding layer containing a synthetic resin, a solid lubricant, and an additive, the synthetic resin being polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, or a combination thereof, the solid lubricant being polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof, the content of the solid lubricant in the sliding layer being 5.0% by volume or more and 40.0% by volume or less, the additive being bentonite, a smectite clay mineral, silica, polyamide, or a combination thereof, and the content of the additive in the sliding layer being 0.1% by volume or more and 9.0% by volume or less.

[0011] The sliding member includes a sliding layer, and the sliding layer contains a synthetic resin selected from polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, and a combination thereof, thereby increasing the hardness of the sliding layer and suppressing the entrapment of foreign matter. This improves the abrasion resistance of the sliding layer during sliding, resulting in a sliding material that can withstand long-term use. Furthermore, the solid lubricant is polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof. By adjusting the content of the solid lubricant in the sliding layer to the above range, the wear resistance of the sliding member is improved. Furthermore, the additive is bentonite, smectite clay mineral, silica, polyamide, or a combination thereof. By adjusting the content of the additive in the sliding layer to the above range, the resin composition constituting the sliding layer is imparted with thixotropy. This improves the surface properties of the sliding layer and enhances its wear resistance, resulting in a sliding member with high hardness, torque reduction effect, and wear resistance.

[0012] (2) In the above (1), the skewness Ssk of the surface of the sliding layer may be -0.10 or more, and the level difference Sk of the core portion of the surface of the sliding layer may be 2.5 μm or less. When the skewness Ssk of the surface of the sliding layer is -0.10 or more and the level difference Sk of the core portion of the surface of the sliding layer is 2.5 μm or less, the torque reduction effect of the sliding member can be further enhanced. The "skewness (degree of deviation) Ssk" and the "level difference Sk of the core portion" are parameters of three-dimensional surface texture defined in ISO 25178 and can be measured using a laser microscope. Specifically, the "skewness (degree of deviation) Ssk" is a parameter of surface roughness defined in ISO 25178 surface texture and represents the symmetry of the height distribution. When Ssk = 0, the height distribution is symmetrical from top to bottom, when Ssk > 0, the surface has many fine peaks, and when Ssk < 0, the surface has many fine valleys. The "level difference Sk of the core part" is the value obtained by subtracting the minimum height from the maximum height of the core part in the load curve that represents the ratio of the actual part of the surface unevenness in the height direction to the void part.

[0013] (3) In the above (1) or (2), the content of the additive in the sliding layer may be 0.5 volume % or more and 4.0 volume % or less. By having the content of the additive in the above range, the surface properties of the sliding layer can be further improved, and the wear resistance can be further increased. Furthermore, in the sliding member, the hardness of the sliding layer can be further increased, and the effect of suppressing the entrapment of foreign matter can be further improved.

[0014] (4) In any of (1) to (3) above, the solid lubricant may have an average particle size of 0.1 μm or more and 10.0 μm or less. By having the average particle size of the solid lubricant within the above range, the surface properties can be improved and the amount of wear can be further reduced. Furthermore, the solid lubricant can be evenly distributed on the surface of the sliding layer, reducing the sliding resistance with the mating material, thereby reducing the amount of wear of the sliding layer.

[0015] The "average particle size" refers to the median diameter (D50), which is the value at which the volume-based cumulative distribution calculated in accordance with JIS-Z-8819-2:2001 is 50%. Specifically, the median diameter (D50) can be measured using the following method. Measurement is performed using a laser diffraction particle size distribution analyzer. A scattering measurement mode is employed, and a laser beam is irradiated onto a wet cell in which a dispersion liquid in which particles of the sample to be measured are dispersed in a dispersion solvent is circulated, to obtain a scattered light distribution from the measurement sample. The scattered light distribution is then approximated by a log-normal distribution, and the particle diameter at which the cumulative degree is 50% (D50) is taken as the median diameter.

[0016] [Details of Embodiments of the Present Disclosure] Hereinafter, a sliding member according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0017] <Sliding Member> A sliding member according to an embodiment of the present disclosure includes a sliding member body and a sliding layer laminated directly on the surface of the sliding member body. Fig. 1 is a schematic cross-sectional view showing a sliding member 1 according to an embodiment of the present disclosure. The sliding member 1 in Fig. 1 is plate-shaped. The sliding member 1 includes a sliding member body 2 in the form of a plate having a front surface (the upper surface of the sliding member body 2 in Fig. 1 ) and a back surface (the lower surface of the sliding member body 2 in Fig. 1 ), and a sliding layer 3 laminated directly on the surface of the sliding member body 2.

[0018] [Sliding Member Body] The main component of the sliding member body 2 is not particularly limited and may be, for example, a metal, super engineering plastic, ceramic, or carbon material. Examples of the metal include iron alloys such as stainless steel, nickel, aluminum, aluminum alloys, copper, and copper alloys. Among these, stainless steel or nickel may be used as the metal due to its excellent ductility and heat resistance. The metals may be used alone or in combination of two or more. Examples of the super engineering plastic include polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, liquid crystal polymer, polysulfone, and polyethersulfone. Examples of the ceramic include alumina, aluminum nitride, silicon nitride, boron nitride, silicon carbide, zirconia, cordierite, sialon, steatite, sapphire, and cermet. Examples of the carbon material include diamond, graphite, C / C composites, and C / SiC composites. The term "main component" refers to the component with the highest content in terms of mass, for example, a component with a content of 60 mass % or more.

[0019] The shape of the sliding member body 2 is not particularly limited and can be changed appropriately depending on the application. For example, it is not limited to a plate-like, cylindrical, conical, elliptical cone-like, pyramidal, gourd-like, elliptical cylinder-like, or rectangular cylinder-like shape, and various sliding member shapes such as a rotor can be adopted.

[0020] The average thickness of the sliding member body 2 is not particularly limited and can be changed appropriately depending on the application. The sliding member body 2 may have a through-hole.

[0021] [Sliding Layer] In this embodiment, the sliding layer 3 is laminated directly on the surface of the sliding member body 2. The sliding layer 3 contains a synthetic resin, a solid lubricant, and an additive. Since the sliding layer 3 contains a synthetic resin, a solid lubricant, and an additive, it has excellent wear resistance.

[0022] The sliding layer 3 does not need to be laminated on the entire surface of the sliding member body 2, but only needs to be laminated on at least the sliding surface of the sliding member body 2. For example, when the sliding member body 2 is plate-shaped as shown in Fig. 1 , the sliding layer 3 may be laminated directly on only a portion of the surface of the sliding member body 2, or may be laminated directly on the front and back surfaces of the sliding member body 2. Furthermore, when the sliding member body 2 is cylindrical, the sliding layer may be laminated directly on the entire outer peripheral surface of the sliding member body 2, or may be laminated directly on only a portion of the outer peripheral surface of the sliding member body. Furthermore, the sliding surface of the sliding layer 3 does not need to be flat, and a pattern such as grooves or dimples (depressions) may be formed on the surface.

[0023] The sliding layer 3 may be a coating layer or may be made of a film. When the sliding layer 3 is made of a coating layer or a film, it becomes easy to control the accuracy of the surface roughness of the sliding layer 3 and the average thickness of the sliding layer 3.

[0024] The lower limit of the average thickness of the sliding layer 3 may be 0.1 μm or 5 μm. On the other hand, the upper limit of the average thickness may be 70.0 μm or 50.0 μm. If the average thickness is less than 0.1 μm, there is a risk that the abrasion resistance when foreign matter is caught may decrease. On the other hand, if the average thickness exceeds 70.0 μm, there is a risk that the elasticity of the sliding member 1 may decrease. Here, the "average thickness" refers to the average value of thicknesses measured at any ten points.

[0025] The lower limit of the skewness Ssk on the surface of the slide layer 3 may be −0.10 or 0. When the skewness Ssk is −0.10 or more, the torque reduction effect can be improved. On the other hand, the upper limit of the skewness Ssk is not particularly limited, but may be, for example, 5.0 or 2.1.

[0026] The upper limit of the level difference Sk of the core portion may be 2.5 μm, 2.0 μm, or 1.8 μm. By making the level difference Sk of the core portion 2.5 μm or less, the torque reduction effect can be improved. On the other hand, the lower limit of the level difference Sk of the core portion is not particularly limited, but may be, for example, 0.1 μm or 0.5 μm.

[0027] (Synthetic Resin) The synthetic resin is polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, or a combination thereof. When the synthetic resin is polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, or a combination thereof, the hardness of the sliding layer 3 can be increased and foreign matter can be prevented from getting caught. Therefore, the abrasion resistance of the sliding layer 3 during sliding can be improved.

[0028] The lower limit of the content of the synthetic resin in the slide layer 3 may be 55 mass %, 60 mass %, or 70 mass %. If the content of the synthetic resin is less than 55 mass %, the slide layer 3 may not have sufficient hardness. On the other hand, the upper limit of the content of the synthetic resin in the slide layer 3 may be 95 mass %, 90 mass %, or 85 mass %. If the content of the synthetic resin exceeds 95 mass %, the proportion of the solid lubricant decreases relatively, and sufficient wear resistance may not be obtained.

[0029] (Solid Lubricant) The sliding layer 3 contains a solid lubricant. When the sliding layer 3 contains a solid lubricant, the wear resistance of the sliding member 1 is improved. The solid lubricant is polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or a combination thereof. Among these, polytetrafluoroethylene and tetrafluoroethylene-perfluoroalkoxyethylene copolymer can exhibit superior wear resistance.

[0030] The lower limit of the content of the solid lubricant in the slide layer 3 is 5.0 vol%, and may be 10 vol%, or 15 vol%. If the content of the solid lubricant is less than 5.0 vol%, the surface properties of the slide layer 3 may be deteriorated, and the wear resistance may be reduced. On the other hand, the upper limit of the content of the solid lubricant is 40.0 vol%, and may be 30 vol%, or 25 vol%. If the content of the solid lubricant exceeds 40.0 vol%, the hardness and surface properties of the slide layer 3 may be deteriorated, and the wear resistance may be reduced.

[0031] The lower limit of the average particle size of the solid lubricant may be 0.1 μm or 0.2 μm. When the average particle size of the solid lubricant is 0.1 μm or more, softening of the slide layer 3 can be suppressed, and the effect of suppressing deterioration of wear resistance and entrapment of foreign matter can be further improved. On the other hand, the upper limit of the average particle size of the solid lubricant may be 10.0 μm or 9.0 μm. When the average particle size of the solid lubricant is 10.0 μm or less, the surface roughness of the slide layer 3 can be further reduced, and an increase in the amount of wear and torque of the slide layer 3 can be suppressed.

[0032] (Additives) The sliding layer 3 contains an additive. The sliding layer 3 contains bentonite, smectite clay minerals, silica, polyamide, or a combination thereof as an additive, which imparts thixotropy to the resin composition constituting the sliding layer. This improves the surface properties of the sliding layer and enhances its wear resistance. The "smectite clay minerals" are a general term for swellable clay minerals, which have a laminated structure of thin-layered crystals. Examples of smectite clay minerals include montmorillonite, nontronite, saponite, and beidellite. The additives may be at least partially modified in structure, such as organically modified bentonite, organically modified montmorillonite, or urea-modified polyamide. The "organically modified bentonite" is bentonite reacted with an organic cation, and the organic cation functions as an organifying agent that imparts organic groups to the bentonite.

[0033] The lower limit of the content of the additive in the slide layer 3 is 0.1 vol%, or may be 0.2 vol%, or may be 0.5 vol%. If the content of the additive is less than 0.1 vol%, the surface properties of the slide layer 3 may be deteriorated, and the wear resistance may be reduced. On the other hand, the upper limit of the content of the additive is 9.0 vol%, or may be 7.0 vol%, or may be 5.0 vol%, or may be 4.0 vol%. If the content of the additive exceeds 9.0 vol%, the hardness and surface properties of the slide layer 3 may be deteriorated, and the wear resistance may be reduced.

[0034] If necessary, additive components other than the above-mentioned additives may be contained in the sliding layer 3. Specifically, additives such as anti-settling agents, dispersants, anti-foaming agents, coloring pigments, antioxidants, ultraviolet absorbers, antistatic agents, surfactants, leveling agents, and rheology control agents may be used.

[0035] [Method for Manufacturing Sliding Member] A method for manufacturing the sliding member according to one embodiment includes a step of directly laminating a sliding layer containing a synthetic resin, a solid lubricant, and an additive on the surface of the sliding member body.

[0036] (Laminating Step) In this step, a sliding layer containing a synthetic resin, a solid lubricant, and an additive is directly laminated on the surface of the sliding member body.

[0037] Examples of the lamination method include a method of applying a coating material to the outer peripheral surface of the sliding member body by dip coating, electrostatic coating, air spray coating, inkjet coating, dispenser coating, electrodeposition coating, screen printing, spin coating, die coating, roll coating, wire bar coating, blade coating, or gravure coating, and a method of thermocompression bonding a film containing a synthetic resin, a solid lubricant, and an additive to the sliding member body.

[0038] Examples of the paint include a paint in which a resin composition containing a synthetic resin, a solid lubricant, and an additive is dispersed or dissolved in a solvent. Examples of the solvent include amide-based solvents such as N-methylpyrrolidone, 2-pyrrolidone, dimethylacetamide, N,N-dimethylformamide, and N,N-diethylformamide, as well as mixtures of the amide-based solvents with other solvents such as water, alcohols, ketones, ethers, esters, amines, and combinations thereof. The resin composition can be prepared by blending predetermined amounts of the synthetic resin, solid lubricant, and additive, and mechanically stirring and mixing the mixture in the solvent.

[0039] The lower limit of the solids concentration of the coating material may be 5 mass%, 25 mass%, or 40 mass%, while the upper limit of the solids concentration of the coating material may be 60 mass%, 50 mass%, or 45 mass%. By setting the solids concentration of the coating material within the above range, the coatability can be improved, and as a result, a coating film with few coating defects can be easily and reliably formed.

[0040] The lower limit of the viscosity of the paint may be 100 cP or 180 cP. On the other hand, the upper limit of the viscosity of the paint may be 100,000 cP or 50,000 cP. By setting the viscosity of the paint within the above range, the coatability can be improved, and as a result, a coating film with few coating defects can be easily and reliably formed. Here, "viscosity" refers to a value measured in accordance with JIS-K5600-2-2:1999 "General Test Methods for Paints - Part 2: Properties and Stability of Paints - Section 2: Viscosity."

[0041] When a sliding layer made of a film is used in the lamination step, the lower limit of the heating temperature of the film in the step of thermocompression bonding of the film to the sliding member body may be the melting point of the fluororesin minus 20°C, or may be the melting point. On the other hand, the upper limit of the heating temperature may be the melting point of the fluororesin plus 60°C, or may be the melting point plus 30°C. If the heating temperature is below the lower limit, there is a risk that the adhesion between the film and the sliding member body will be insufficient. Conversely, if the heating temperature exceeds the upper limit, there is a risk that the releasability from the mold used for compression bonding will deteriorate, and the fluororesin will be torn off and transferred to the mold, resulting in an uneven compression surface.

[0042] When the film is thermocompression-bonded to the sliding member body, the upper limit of the pressing pressure may be 50 MPa or 10 MPa. On the other hand, the lower limit of the pressure may be 10 kPa or 100 kPa. If the pressure is below the lower limit, there is a risk of insufficient adhesion between the film and the sliding member body. Conversely, if the pressure exceeds the upper limit, there is a risk of damage to the sliding member body or the pressing jig, or an increase in equipment costs.

[0043] When the film is thermocompressed to the sliding member body, the heating and pressing time can be, for example, 5 minutes to 2 hours. In addition, the pressing time can be shortened by using a high-frequency welding machine to perform the pressure bonding while applying high frequency waves.

[0044] After coating the outer peripheral surface of the sliding member body with a paint or thermocompression bonding a film, the sliding member body is placed in a heating furnace and heated to bake the resin composition. The baking process can evaporate the solvent in the paint. The heating temperature for baking the coating film of the resin composition can be, for example, 350°C or higher and 450°C or lower. The heating time for baking the coating film can be, for example, 10 minutes or higher and 60 minutes or lower. By setting the heating temperature and heating time within the above ranges, a film with excellent density can be formed while suppressing decomposition of the synthetic resin. The sliding member body is then cooled, and a sliding layer is laminated on the surface of the sliding member body.

[0045] As described above, the sliding layer does not need to be laminated on the entire surface of the sliding member body, but it is sufficient that it is laminated at least on the sliding surface of the sliding member body.

[0046] The synthetic resin may be crosslinked by irradiating the sliding layer with ionizing radiation. The ionizing radiation is applied to the sliding layer in a low-oxygen atmosphere at a temperature equal to or higher than the melting point of the synthetic resin. The ionizing radiation is preferably applied before the lamination step. By applying the ionizing radiation before the lamination step, deterioration of the sliding member body due to the ionizing radiation can be suppressed.

[0047] The lower limit of the heating temperature for the ionizing radiation irradiation may be 5°C higher than the melting point of the synthetic resin, or may be 10°C higher than the melting point of the synthetic resin. Meanwhile, the upper limit of the heating temperature may be 50°C higher than the melting point of the synthetic resin, or may be 30°C higher than the melting point of the synthetic resin. The specific heating temperature can be appropriately changed depending on the type of synthetic resin, and the lower limit may be 320°C or 330°C. Meanwhile, the upper limit of the heating temperature may be 480°C or 350°C. Irradiating the synthetic resin with ionizing radiation at the above heating temperatures can promote intermolecular crosslinking while suppressing scission of the main chain of the synthetic resin. If the heating temperature exceeds the above upper limit, the synthetic resin may decompose. Here, the "melting point of the resin" refers to the peak melting point temperature measured by a differential scanning calorimeter (DSC) in accordance with JIS-K7121:2012, "Method for measuring transition temperatures of plastics."

[0048] The upper limit of the oxygen concentration in the low-oxygen atmosphere may be 100 ppm, 10 ppm, or 5 ppm. If the oxygen concentration exceeds the upper limit, the synthetic resin may be decomposed by irradiation with ionizing radiation.

[0049] Examples of the ionizing radiation include gamma rays, electron beams, X-rays, neutron beams, and high-energy ion beams, with electron beams being preferred. The lower limit of the ionizing radiation exposure dose may be 10 kGy, 70 kGy, or 200 kGy. Meanwhile, the upper limit of the exposure dose may be 2,000 kGy, 1,200 kGy, or 400 kGy. If the exposure dose is less than the lower limit, the crosslinking reaction of the synthetic resin may not proceed sufficiently. Conversely, if the exposure dose exceeds the upper limit, the main chain of the synthetic resin may be scissioned. Therefore, by setting the exposure dose within the above range, crosslinking can proceed sufficiently while suppressing scission of the main chain of the synthetic resin. The acceleration voltage may be, for example, 50 kV or more and 10,000 kV or less.

[0050] The sliding member has high hardness, excellent torque reduction effect, and excellent wear resistance, and is therefore suitable for use as a sliding member for rotor-type compressors such as vanes, shoes, and side plates, and as a sliding member provided in rotary devices and parts such as rotors for oil pumps.

[0051] [Other Embodiments] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the configurations of the above-described embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0052] In the above embodiment, the sliding layer is laminated directly on the surface of the sliding member body, but an intermediate layer may be further provided between the sliding member body and the sliding layer. By providing the sliding member with an intermediate layer, the hardness of the sliding layer can be further increased. An example of the intermediate layer is a resin layer containing the above synthetic resin as a main component.

[0053] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0054] <Sliding Members No. 1 to No. 35> [No. 1 to No. 34] A sliding layer containing a synthetic resin, solid lubricant, and additives in the amounts listed in Table 1 was directly laminated on a stainless steel plate with an average thickness of 1 mm as the sliding member body, using the following procedure. Note that a "-" in the table indicates that the corresponding material was not blended. First, the solid lubricant and additives listed in Table 1, as well as the surfactant "Ftergent 710FL" manufactured by Neos Corporation, were added to the synthetic resin listed in Table 1 so that the mass ratio relative to the solid lubricant was 0.12. The content of the synthetic resin was adjusted so that the total content of the solid lubricant, additive, and surfactant was 100% by mass. That is, the contents of the solid lubricant, additive, and surfactant were as described above, with the synthetic resin content being the remainder of 100% by mass. The mixture was then stirred at 1200 rpm for 3 hours using a magnetic stirrer. For the ball-on test in oil using a rheometer, a dedicated aluminum jig φ12 mm was coated with a non-wire bar coater OSP-120-L60 manufactured by AS ONE Corporation so that the dry film thickness was approximately 10 μm, and then dried at 100 ° C. for 10 minutes. After that, the test piece was baked at 360 ° C. for 15 minutes. Furthermore, for the pencil hardness and ring-on-disc tests, both left and right sides of a 40 mm x 40 mm, 1 mm thick SUS (Steel Use Stainless Steel) plate were fixed with 50 μm masking tape. Furthermore, three pieces of masking tape were stacked on top of the masking tape applied for fixation, and the masking tape was fixed so that the total height from the surface of the SUS plate was 200 μm. About 1 g of the prepared coating material was dropped onto the substrate and applied using AS ONE's "Non-Wire Bar Coater OSP-05-L60" so that the dry film thickness was approximately 20 μm. After drying at 100°C for 10 minutes, the substrate was baked at 360°C for 15 minutes to prepare a 40 x 40 mm test piece. The film thicknesses in Table 1 are dry film thicknesses.

[0055] [No. 35] No. 35 was prepared as a comparative example in the same manner as Nos. 1 to 34, except that no sliding layer was laminated on the sliding member body.

[0056] The materials used are as follows: (Synthetic Resins) (1) Polyimide 1 (PI) "UPIA-AT-1001" manufactured by UBE, glass transition temperature 274°C to 278°C (2) Polyimide 2 (PI) I.S. "Pyre M.L." manufactured by T Co., Ltd. Glass transition temperature: 300°C or higher (3) Polyimide 3 (PI) "UPIA-ST-1001" manufactured by UBE Co., Ltd. Glass transition temperature: 322°C to 324°C (4) Polyamideimide (PAI) "Vylomax HR-11NN" manufactured by Toyobo Co., Ltd. Glass transition temperature: 300°C (5) Polybenzimidazole (PBI) "MRS0810H" manufactured by PBI Advanced Materials Co., Ltd. Glass transition temperature: 427°C (6) Polyimide 1 and polyamideimide (PI / PAI) A blend of the above "UPIA-AT-1001" manufactured by UBE Co., Ltd. and "Vylomax HR-11NN" manufactured by Toyobo Co., Ltd. (Additives) (1) Modified bentonite 1 Organically modified bentonite: "GARAMITE-7305" manufactured by BYK Corporation (2) Modified Bentonite 2 Organically modified bentonite: "CLAYTONE-MPZ" manufactured by BYK Corporation (3) Modified Montmorillonite "CLAYTONE APA" manufactured by BYK Corporation (4) Polyamide The polyamide was prepared by the following procedure. First, 0.60 g of metaphenylenediamine was dissolved in a mixture of 6.50 g of methyl ethyl ketone, 1.20 g of water, and 1.00 g of dimethylethanolamine to prepare solution A. Next, 1.13 g of isophthaloyl chloride was dissolved in 3.20 g of methyl ethyl ketone to prepare solution B. Then, while stirring solution A with a magnetic stirrer, the entire amount of solution B was added, and the mixture was allowed to react for 3 minutes with continued stirring. Next, the entire amount of the solution after the reaction was added to 100 g of pure water to precipitate the synthesized polymer. The precipitated polymer was then filtered using filter paper, and the precipitated polymer was recovered. The recovered precipitate was then dried at 100° C. for 1 hour to obtain 0.85 g of polyamide.(5) Urea-modified polyamide BYK "BYK430" (6) Silica Tokuyama "QS-102" (Solid lubricant) (1) Polytetrafluoroethylene 1 (PTFE1) 3M Japan "TF9207Z", average particle size 4.0 μm (2) Polytetrafluoroethylene 2 (PTFE2) Kitamura "KTL-500f", average particle size 0.3 μm (3) Polytetrafluoroethylene 3 (PTFE3) 3M Japan "TF9201Z", average particle size 8.0 μm (4) Tetrafluoroethylene-perfluoroalkoxyethylene copolymer 1 (PFA1) AGC Inc. "EA-2000 PW10", average particle size 2.0 μm (5) Tetrafluoroethylene-perfluoroalkoxyethylene copolymer 2 (PFA2) Mitsui-Chemours Fluoro Products "MJ102", average particle size 20.0 μm (6) Molybdenum disulfide (MoS ２ ) Daizo "T Powder", average particle size 3.5 μm

[0057]

[0058] <Evaluation> Next, the sliding members No. 1 to No. 35 were evaluated for skewness Ssk, level difference Sk of the core portion, torque, amount of wear, pencil hardness, and limit PV value.

[0059] [Parameters of three-dimensional surface texture defined in ISO 25178] (1) Skewness Ssk For slide members No. 1 to No. 35, the skewness Ssk [ / mm ２] was measured. A Keyence VK-X1100 shape analysis laser microscope was used as the measuring device. Measurement conditions included a standard eyepiece type CF IC EPI Plan Apo50X on a 23-inch monitor screen at a total magnification of 1200x, measuring an area of ​​283.0971 x 212.3238 μm, and obtaining height data of 2048 x 1536 points. Reference plane correction was performed using the multi-analysis application software attached to the laser microscope, based on the central 200 x 200 μm portion of the measurement data. After reference plane correction, the skewness Ssk in the central 200 x 200 μm portion was calculated. (2) Core Level Difference Sk For slide members No. 1 to No. 35, the core level difference Sk [μm] of the slide layer surface was measured using the following procedure. The measurement device used was a Keyence VK-X1100 shape analysis laser microscope. Measurement conditions included a standard eyepiece type CF IC EPI Plan Apo50X, a total magnification of 1200x on a 23-inch monitor screen, and measurements were taken over an area of ​​283.0971 x 212.3238 μm, yielding height data of 2048 points x 1536 points. Reference plane correction was performed using the multi-analysis application software provided with the laser microscope, based on the central 200 μm x 200 μm portion of the measurement data. After reference plane correction, the level difference Sk of the core portion of the central 200 μm x 200 μm portion was calculated.

[0060] [Ball-on Test in Oil] (1) Torque: For sliding members No. 1 to No. 35, torque [cN·m] was measured using the following procedure. The mating member used for sliding against the test piece was made of SUJ2 (high-carbon chromium bearing steel) with a ball diameter of 1 mm. The measurement was performed at a temperature of 25±2°C, lubricated with poly-alpha olefin (viscosity equivalent to VG10), under a constant load of 3 N and a sliding speed of 3 mm / sec, and the reaction torque generated in the mating member was measured. The reaction torque is proportional to the coefficient of dynamic friction. An Anton Paar MCR302 rheometer was used as the test device for this measurement. Torque is an indicator of energy efficiency. A torque of 0.65 cN·m or less is considered acceptable, and a torque of 0.50 cN·m or less is considered even better. (2) Wear Amount: For sliding members No. 1 to No. 35, torque was measured using the Anton Paar MCR302 rheometer. The amount of wear [μm] was measured for each of the 35 samples using the following procedure. Using the rheometer, a 120-second sliding test was conducted under a constant load of 3 N and a sliding speed of 3 mm / sec. After the test, a circular sliding groove remained on the sliding member, and the difference in height between the bottom of the sliding groove and the non-sliding surface adjacent to the sliding groove (= the depth of the sliding groove) was measured as the amount of wear. The amount of wear was measured using a Keyence VK-X1100 shape analysis laser microscope and quantified using the "average step" mode of the included multi-analysis application software. The heights of both the sliding surface and the non-sliding surface were calculated over an area of ​​50 μm × 100 μm.

[0061] [Pencil hardness] After sharpening the tip of a pencil into a cone using an electric sharpener, the pencil was polished vertically on waterproof abrasive paper #2000 manufactured by Nihon Kenshi Co., Ltd., so that the flat portion of the tip of the lead was within φ0.9 mm to 1.1 mm. The polished pencil was pressed firmly against the test piece at an angle of about 45° and moved at a speed of approximately 100 mm / sec to evaluate whether the sliding layer was gouged and the substrate was exposed. Specifically, the evaluation was performed in order from 6B, and if the sliding layer was not gouged after three evaluations or the pencil lead broke, the number was considered to be pass. The evaluation was performed by increasing the pencil number until the sliding layer was gouged and the substrate was exposed. Mitsubishi Pencil uni 6B to 9H pencils were used. A rating of 4H or higher can be judged to be good and resistant to scratches, and a rating of 2H or lower can be judged to be easy to scratch and unsuccessful.

[0062] [Limiting PV Value by Dry Ring-on-Disk Wear Test] For sliding members No. 1 to No. 35, the limiting PV value [MPa m / min] of the sliding surface was measured by ring-on-disk wear testing using the following procedure. The measurements were performed under conditions of a constant load of 10 MPa at 23±2°C, with the speed increasing by one step every 3 minutes. Specifically, a ring-shaped mating member made of S45C (carbon steel for mechanical structures) with ring dimensions (outer diameter / inner diameter) of φ11.6 mm / φ7.4 mm was used. Then, under dry lubrication conditions, a load of 10 MPa (surface pressure: P) was applied to the mating member, and the test specimen was rotated at a predetermined speed (rotational speed: V), and the dynamic friction coefficient was measured based on the reaction torque generated in the mating member. At this time, the speed started at 1 m / min in step (1), increased to 5 m / min in step (2), and increased to 10 m / min in step (3). Thereafter, the speed was increased by 10 m / min for each step, and the limit PV value was measured. In the present disclosure, the PV value just before the sliding member body was exposed was defined as the limit PV value. For the above measurement, an "EFM-3-1010-S" test device manufactured by AND was used. The limit PV value of the sliding surface can be used to evaluate the seizure resistance and wear resistance.

[0063] Table 2 shows the evaluation results of the skewness Ssk, the level difference Sk of the core portion, the torque, the amount of wear, the pencil hardness, and the limit PV value for the sliding members No. 1 to No. 35. Note that "-" in Table 2 indicates that the corresponding evaluation was not performed.

[0064]

[0065] As shown in Table 2, Nos. 2 to 5, 7 to 11, 13 to 19, and 22 to 32, in which the sliding layer contained polyimide, polyamideimide, or polybenzimidazole as the synthetic resin, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, or molybdenum disulfide as the solid lubricant, and the additive contained bentonite, smectite clay mineral, silica, or polyamide, the content of the solid lubricant was 5.0% by volume or more and 40.0% by volume or less, and the content of the additive was 0.1% by volume or more and 9.0% by volume or less, showed good results in all of torque, wear amount, hardness, and limit PV value.

[0066] On the other hand, No. 1, which contained no additives and had an Sk of 3.16, exhibited high torque. No. 6, which contained more than 9.0% by volume of the additive, was poorly evaluated in all of torque, wear, hardness, and limit PV. No. 12, which contained less than 5.0% by volume of solid lubricant, exhibited high torque and a low limit PV. Nos. 20 and 21, which contained more than 40.0% by volume of solid lubricant, were poorly evaluated in wear, hardness, and limit PV. No. 33, which contained polytetrafluoroethylene as the synthetic resin but no solid lubricant or additives, was poorly evaluated in wear and hardness. No. 34, which contained no solid lubricant or additives, exhibited high torque and a low limit PV. No. 35, which did not have a sliding layer, exhibited high torque and a significant low limit PV.

[0067] From the above, it was shown that the sliding member has high hardness, and is excellent in torque reduction effect and wear resistance.

[0068] 1 Sliding member 2 Sliding member body 3 Sliding layer

Claims

1. A sliding member including a sliding layer, The sliding layer contains a synthetic resin, a solid lubricant, and an additive, the synthetic resin is polyimide, polyamideimide, polybenzimidazole, polyphenylsulfone, polyethersulfone, polyetheretherketone, or a combination thereof; the solid lubricant is polytetrafluoroethylene, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, a tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof; The content of the solid lubricant in the sliding layer is 5.0 vol. % or more and 40.0 vol. % or less, The additive is bentonite, a smectite clay mineral, silica, a polyamide, or a combination thereof; A sliding member, wherein the content of the additive in the sliding layer is 0.1 vol % or more and 9.0 vol % or less.

2. The skewness Ssk of the surface of the sliding layer is −0.10 or more, 2. The sliding member according to claim 1, wherein a level difference Sk of the surface of the sliding layer to the core portion is 2.5 μm or less.

3. 3. The sliding member according to claim 1, wherein the content of the additive in the sliding layer is 0.5% by volume or more and 4.0% by volume or less.

4. 3. The sliding member according to claim 1, wherein the average particle size of the solid lubricant is 0.1 μm or more and 10.0 μm or less.

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