Oil / seal lubrication system

Abstract

This oil / seal lubrication system comprises a seal member, and a slide member that moves relative to the seal member and comes into contact with the seal member via lubricating oil. The seal member contains an inorganic filler, and at least one of the seal member and the lubricating oil contains an ashless friction modifier.

Description

Oil / Seal Lubrication System

[0001] The present invention relates to an oil / seal lubrication system.

[0002] BACKGROUND ART Lubricating oils are used in mechanical elements such as hydraulic machines, compressors, turbines, gear elements, and bearings in automobiles, industrial machinery, and the like to improve the lubricity of sliding members, and sealing members (oil seals) are provided to prevent the lubricating oil from leaking from the mechanical elements.

[0003] Seal members come into contact with and slide on sliding members such as rotating shafts and hydraulic cylinders. Therefore, there is a demand for seal members that have high sealing performance while reducing friction so as to reduce sliding resistance. For example, Patent Document 1 discloses a fluororubber composition suitable for use as a sealing material that can achieve low friction while maintaining sealing performance as the oil pump volume increases from the initial use of an oil seal to after wear. The fluororubber composition contains 1 to 100 parts by weight of a needle-like or fibrous filler having an average particle diameter of 5 μm or less, an average particle length of 40 to 60 μm, and an aspect ratio of 10 to 12 per 100 parts by weight of the fluororubber.

[0004] International Publication No. 2014 / 024661

[0005] One aspect of the present invention aims to provide an oil / seal lubrication system that enables low friction between a seal member and a sliding member that moves relative to the seal member and contacts the seal member via lubricating oil.

[0006] According to the studies of the present inventors, it has been found that friction can be reduced by incorporating an inorganic filler into the seal member and incorporating an ashless friction modifier into at least one of the seal member and the lubricating oil.

[0007] The present invention includes the following aspects. [1] An oil / seal lubrication system comprising a seal member and a sliding member that moves relative to the seal member and contacts the seal member via a lubricating oil, wherein the seal member contains an inorganic filler, and at least one of the seal member and the lubricating oil contains an ashless friction modifier. [2] The oil / seal lubrication system according to [1], wherein both the seal member and the lubricating oil contain an ashless friction modifier. [3] The oil / seal lubrication system according to [1] or [2], wherein the inorganic filler is at least one selected from the group consisting of carbon black, metal oxides, metal hydroxides, and silicate minerals. [4] The oil / seal lubrication system according to any one of [1] to [3], wherein the ashless friction modifier is at least one selected from the group consisting of fatty acid ester-based compounds, phosphorus-based compounds, ether-based compounds, alcohol-based compounds, amide-based compounds, amine-based compounds, imide-based compounds, sulfur-based compounds, and phosphorus-sulfur-based compounds. [5] The oil / seal lubrication system according to any one of [2] to [4], wherein the friction modifier in the seal member and the friction modifier in the lubricating oil are fatty acid ester compounds. [6] The oil / seal lubrication system according to [5], wherein the fatty acid ester compound contains a compound having a hydrocarbon group, an ester group, and a hydroxyl group. [7] The oil / seal lubrication system according to any one of [1] to [6], wherein the lubricating oil contains at least one base oil selected from the group consisting of base oils classified in any one of API base oil classification groups I, II, III, IV, and V. [8] The oil / seal lubrication system according to any one of [1] to [7], wherein the lubricating oil contains a base oil having a viscosity index of 80 or more. [9] The oil / seal lubrication system according to any one of [1] to [7], wherein the lubricating oil contains at least one base oil selected from the group consisting of base oils classified in any one of API base oil classification groups I, II, III, IV, and V. Ｐ is 60 or more, and % C Ａ

[10] The oil / seal lubrication system according to any one of [1] to [8], wherein the lubricating oil contains an oxygen-containing base oil.

[11] The oil / seal lubrication system according to any one of [1] to

[10] , wherein the friction coefficient measured with an MTM testing machine using the seal member and the lubricating oil is 0.050 or less.

[0008] According to one aspect of the present invention, it is possible to provide an oil / seal lubrication system that enables low friction between a seal member and a sliding part that moves relative to the seal member and contacts the seal member via lubricating oil.

[0009] FIG. 1 is a schematic diagram illustrating one embodiment of an oil / seal lubrication system.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional view showing an embodiment of an oil / seal lubrication system;

[0011] 1, an oil / seal lubrication system 1 according to one embodiment is installed in an annular gap between a housing 2 and a rotating shaft (sliding member) 3, which are two members assembled concentrically and rotatably relative to each other, and seals the annular gap. This prevents leakage of the sealed object, such as lubricating oil present on the sealed object side O.

[0012] The oil / seal lubrication system 1 includes an annular seal member 5 that fits into the inner peripheral surface of a shaft bore provided in a housing 2, and a reinforcing ring 4 that provides fitting rigidity to the seal member 5. The reinforcing ring 4 is a metal annular member with an L-shaped cross section that has a cylindrical portion 4a that is provided along the inner peripheral surface of the shaft bore and an inward flange portion 4b that extends radially inward from the end of the cylindrical portion 4a on the atmosphere side A. The seal member 5 is made of a rubber-like elastic material that is baked and fixed integrally from the outer peripheral surface of the cylindrical portion 4a of the reinforcing ring 4 to the end face of the atmosphere side A and the end face of the inward flange portion 4b on the sealed side O.

[0013] Of the seal member 5, an outer circumferential seal portion 6 fixed to the outer circumferential surface of the cylindrical portion 4a of the reinforcing ring 4 has a predetermined interference with the inner circumferential surface of the axial hole of the housing 2. The outer circumferential seal portion 6 is firmly fixed to the inner circumferential surface of the axial hole by receiving fitting rigidity from the cylindrical portion 4a of the reinforcing ring 4, and prevents leakage of the sealed object from the inner circumferential surface of the axial hole. Note that in another embodiment, a configuration (metal fitting type) can be adopted in which the outer circumferential seal portion 6 is not provided and the cylindrical portion 4a of the reinforcing ring 4 is directly fitted into the inner circumferential surface of the axial hole.

[0014] On the rotating shaft 3 side of the seal member 5, there are provided a seal lip 7 extending radially inward from the inner end of the inward flange portion 4b of the reinforcing ring 4 toward the sealed side O, and a dust lip 8 extending radially inward conversely toward the atmosphere side A. The dust lip 8 has a plate-shaped cross section, and the tip of the dust lip 8 is in slidable sealing contact with the circumferential surface of the rotating shaft 3. This prevents dust from entering from the atmosphere side A.

[0015] The seal lip 7 has a sealed-side inclined surface 9 facing the sealed side O, an atmosphere-side inclined surface 11 facing the atmosphere side A, and a sliding surface 10 arranged between the sealed-side inclined surface 9 and the atmosphere-side inclined surface 11. The sealed-side inclined surface 9 of the seal lip 7 is inclined from the edge of the sealed side O of the sliding surface 10 toward the sealed side O so as to gradually increase the distance from the circumferential surface of the rotating shaft 3. The atmosphere-side inclined surface 11 of the seal lip 7 is inclined from the edge of the atmosphere side A of the sliding surface 10 toward the atmosphere side A so as to gradually increase the distance from the circumferential surface of the rotating shaft 3.

[0016] A sliding surface 10 is provided between the sealed side inclined surface 9 and the atmosphere side inclined surface 11 so as to follow the circumferential surface of the rotating shaft 3. That is, the lip tip portion of the seal lip 7 is formed such that the sealed side inclined surface 9, the sliding surface 10, and the atmosphere side inclined surface 11 are continuously formed from the sealed side O to the atmosphere side A, and constitutes a flat-type sliding portion with a substantially trapezoidal cross section.

[0017] The lip tip of the seal lip 7 has a predetermined interference with the circumferential surface of the rotating shaft 3. In addition, a garter spring 14 that applies tension to the lip tip of the seal lip 7 against the rotating shaft 3 is attached to the outer circumferential side of the seal lip 7, at a position that is the back surface of the sliding surface 10. Therefore, when the oil / seal lubrication system 1 is attached to the rotating shaft 3, the seal lip 7 is elastically deformed so as to expand in diameter, and its elastic restoring force makes slidable sealing contact with the circumferential surface of the rotating shaft 3.

[0018] A hard material is preferably used for the rotating shaft 3. Examples of hard materials include carbon steel, low-alloy steel, stainless steel, and surface-coated materials thereof. The hardness of the hard material may be 10 HRC or more, 20 HRC or more, or 30 HRC or more, and is preferably 40 HRC or more or 50 HRC or more under usage conditions that are prone to wear. The surface roughness of the circumferential surface of the rotating shaft 3 (the portion that comes into contact with the seal member 5) may be 1 μm Ra or less, 0.6 μm Ra or less, or 0.5 μm Ra or less, and is preferably 10 μm Rz or less, 6 μm Rz or less, or 4 μm Rz or less.

[0019] The oil / seal lubrication system 1 described above is preferably applied to rotating shafts of mechanical elements such as automobiles, electric vehicles, motorcycles, bicycles, aircraft, railroad vehicles, construction machinery, agricultural machinery, hydraulic machinery, compressors, robots, turbines, various industrial machinery such as semiconductor manufacturing equipment, information electronic devices, office automation equipment, home appliances, drones, gear elements, and bearings. The higher the rotation speed of the rotating shaft, the greater the durability of the seal members, lubricant, and rotating shaft due to energy savings and heat suppression achieved by reduced friction. Therefore, the oil / seal lubrication system 1 according to this embodiment is particularly preferably applied to such high-speed rotating shafts. While this embodiment has been described using an example of application to a rotating shaft, in another embodiment, the oil / seal lubrication system can also be applied to the above-mentioned mechanical elements, such as shock absorbers and hydraulic cylinders.

[0020] The oil / seal lubrication system 1 is suitable for use in electric vehicles (EVs). The oil / seal lubrication system 1 is particularly suitable for use in the motor drive unit of an EV drive unit (e-axle), where it can suppress torque and reduce wear on the seal member 5, enabling a longer lifespan. The oil / seal lubrication system 1 is also suitable for use in robots, which operate at slower speeds than automobile engines and require frequent rotational changes.

[0021] The sealing member 5 contains an inorganic filler. The shape of the inorganic filler may be, for example, particulate, fibrous, layered, blocky, rectangular, or columnar.

[0022] As the inorganic filler, for example, at least one selected from the group consisting of carbon black, metal oxides, metal hydroxides, and silicate minerals can be used. As the metal oxide, for example, iron (III) oxide (Fe ２ O ３ ), chromium (III) oxide (Cr ２ O ３ ), titanium dioxide (TiO ２ ), aluminum oxide (Al ２ O ３ ), magnesium oxide (MgO), zinc oxide (ZnO), etc. Examples of the metal hydroxides include magnesium hydroxide and aluminum hydroxide. Examples of the silicate minerals include silica, wollastonite, talc, mica, etc. Among these, from the viewpoints of availability and adsorption to ashless friction modifiers, metal oxides, metal hydroxides, or silicate minerals are preferred, with iron(III) oxide, chromium(III) oxide, titanium dioxide, aluminum hydroxide, silica, wollastonite, or talc being preferred, iron(III) oxide, chromium(III) oxide, titanium dioxide, aluminum hydroxide, or wollastonite being more preferred, and iron(III) oxide, chromium(III) oxide, titanium dioxide, or aluminum hydroxide being even more preferred. As the inorganic filler, from the viewpoint of obtaining a particularly significant effect of reducing friction by the friction modifier described below, an iron-based filler is preferred, and a filler containing iron(III) oxide is particularly preferred.

[0023] The content of the inorganic filler is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 50 parts by mass or more, relative to 100 parts by mass of the rubber component in the sealing member 5, and is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, and particularly preferably 150 parts by mass or less.

[0024] In one embodiment, the sealing member 5 may be a vulcanized molded product (also referred to as a cross-linked molded product) of a rubber composition containing a rubber component and an inorganic filler. In other words, the sealing member may further contain a rubber component (vulcanized (cross-linked) rubber) in addition to the inorganic filler. The sealing member 5 can be obtained by molding the rubber composition by, for example, heat pressing (primary vulcanization) at 160 to 200°C for 3 to 30 minutes, and, if necessary, secondary vulcanization at 150 to 250°C for 0.5 to 24 hours.

[0025] The type of rubber component is not particularly limited. Examples of the rubber component include natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber (nitrile rubber, NBR), hydrogenated nitrile rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), acrylic rubber (ACM), fluororubber (FKM), and silicone rubber. The rubber component is preferably at least one selected from the group consisting of fluororubber (FKM), acrylonitrile-butadiene rubber (nitrile rubber, NBR), silicone rubber, and acrylic rubber (ACM).

[0026] Examples of the fluororubber include polyol-vulcanizable fluororubber and peroxide-crosslinkable fluororubber. The fluororubber is preferably polyol-vulcanizable fluororubber.

[0027] Examples of polyol-vulcanizable fluororubbers include homopolymers and copolymers (e.g., alternating copolymers) of fluorine-containing monomers such as vinylidene fluoride, hexafluoropropene, pentafluoropropene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoroacrylic acid esters, perfluoroalkyl acrylate esters, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), as well as copolymers of these fluorine-containing monomers with propylene. Polyol-vulcanizable fluororubbers are preferably vinylidene fluoride-hexafluoropropene copolymers, vinylidene fluoride-hexafluoropropene-tetrafluoroethylene copolymers, and tetrafluoroethylene-propylene copolymers. Commercially available polyol-vulcanizable fluororubbers may be used as they are.

[0028] The peroxide-crosslinkable fluororubber may be a fluoroelastomer containing iodine and / or bromine in the molecule as a crosslinking site. The fluorine content in the peroxide-crosslinkable fluororubber may be 63 to 71% by weight. The Mooney viscosity ML of the peroxide-crosslinkable fluororubber １＋１０ (121°C) may be 20 to 100.

[0029] The introduction of iodine and / or bromine groups that enable peroxide crosslinking of fluororubber can be carried out by copolymerization reaction in the presence of an iodine and / or bromine group-containing saturated or unsaturated compound.

[0030] When the fluororubber is made to contain a bromine group and / or an iodine group in its side chain, a crosslinking site-forming monomer such as perfluoro(2-bromoethyl vinyl ether), 3,3,4,4-tetrafluoro-4-bromo-1-butene, 2-bromo-1,1-difluoroethylene, bromotrifluoroethylene, perfluoro(2-iodoethyl vinyl ether), or iodotrifluoroethylene can be copolymerized with the above-mentioned fluorine-containing monomer.

[0031] When the fluororubber has an iodine group and / or a bromine group at its terminal, the fluororubber may be a compound represented by the formula: X１ C ｎ F ２ｎ X ２ (X １ : F, Br or I, X ２ A terminally halogenated fluoroalkylene compound represented by the formula (n: Br or I, n: an integer of 1 to 12) is used. From the viewpoint of a balance between reactivity and handling, the terminally halogenated fluoroalkylene compound is preferably a compound in which n is 1 to 6. Specifically, a copolymer containing iodine groups and / or bromine groups is preferably used by copolymerizing a terminally halogenated fluoroalkylene compound such as 1-bromoperfluoroethane, 1-bromoperfluoropropane, 1-bromoperfluorobutane, 1-bromoperfluoropentane, 1-bromoperfluorohexane, 1-iodoperfluoroethane, 1-iodoperfluoropropane, 1-iodoperfluorobutane, 1-iodoperfluoropentane, or 1-iodoperfluorohexane with the above-mentioned fluorine-containing monomer.

[0032] X １ and X ２ When each is I or Br, a crosslinking point is introduced at the end of the fluororubber. １ and X ２ are I or Br, for example, 1-bromo-2-iodotetrafluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, monobromomonoiodoperfluoropentane, monobromomonoiodoperfluoro-n-hexane, 1,2-dibromoperfluoroethane, 1,3-dibromoperfluoropropane, 1,4-dibromoperfluorobutane, 1,5-dibromoperfluoropentane, 1,6-dibromoperfluorohexane, 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodoperfluoropentane, 1,6-diiodoperfluorohexane, and the like.

[0033] The peroxide-crosslinkable fluororubber is preferably a copolymer elastomer such as the following.

[0034] Fluororubber in which iodine groups and / or bromine groups have been introduced into a copolymer elastomer having a copolymerization composition of about 50 to 80 mol % vinylidene fluoride, about 15 to 50 mol % hexafluoropropene, and about 30 to 0 mol % tetrafluoroethylene. Examples of such fluororubbers that can be used include commercially available products such as Viton GAL200S, GBL200S, GBL600S, GF200S, and GF600S manufactured by DuPont; Tecnoflon P457, P757, P459, and P952 manufactured by Solvay-Solex; and Dai-el G952, G901, G902, G912, and G801 manufactured by Daikin Corporation.

[0035] about 50 to 85 mol % vinylidene fluoride, formula: CF ２ =CFORf (Rf: perfluoroalkyl group having 1 to 10 carbon atoms (preferably perfluoromethyl group) or perfluorooxyalkyl group having 1 to 10 carbon atoms and one or more ether bonds in the carbon chain), and about 50 to 0 mol % of tetrafluoroethylene. Fluororubber in which iodine groups and / or bromine groups have been introduced into a copolymer elastomer having a copolymerization composition of about 5 to 50 mol % of perfluorovinyl ether and about 50 to 0 mol % of tetrafluoroethylene. Examples of such fluororubbers that can be used include commercially available products such as Viton GLT200S, GLT600S, GBLT200S, GBLT600S, GFLT200S, and GFLT600S manufactured by DuPont; Tecnoflon PL455, PL855, PL557, PL458, and PL958 manufactured by Solvay-Solex; and Dai-el LT302 and LT301 manufactured by Daikin Corporation.

[0036] The rubber composition may further contain a vulcanizing agent (crosslinking agent). Examples of the vulcanizing agent (crosslinking agent) include polyol and organic peroxide. When the fluororubber is a polyol-vulcanizable fluororubber, polyol is preferably used. When the fluororubber is a peroxide-crosslinkable fluororubber, organic peroxide is preferably used.

[0037] Examples of polyols include 2,2-bis(4-hydroxyphenyl)propane (bisnol A), 2,2-bis(4-hydroxyphenyl)perfluoropropane (bisphenol AF), bis(4-hydroxyphenyl)sulfone (bisphenol S), 2,2-bis(4-hydroxyphenyl)methane (bisphenol F), bisphenol A-bis(diphenyl phosphate), 4,4'-dihydroxydiphenyl, and 2,2-bis(4-hydroxyphenyl)butane. The polyol is preferably bisphenol A or bisphenol AF. These polyols may be in the form of alkali metal salts or alkaline earth metal salts.

[0038] The content of the polyol may be 2 parts by mass or more, preferably 2.5 parts by mass or more, and may be 20 parts by mass or less, preferably 15 parts by mass or less, based on 100 parts by mass of the polyol-vulcanizable fluororubber.

[0039] The polyol may be used in combination with a vulcanization accelerator. That is, the rubber composition may further contain a vulcanization accelerator. The vulcanization accelerator may be a quaternary onium salt, such as a quaternary phosphonium salt or a quaternary ammonium salt, and is preferably a quaternary phosphonium salt. The content of the quaternary onium salt may be 0.5 parts by mass or more, preferably 1 part by mass or more, and may be 10 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the polyol-vulcanizable fluororubber.

[0040] The quaternary phosphonium salt has the formula: １ R ２ R ３ R ４ 〕 ＋ X － In the formula, R １ ~R ４ are each independently an alkyl group, an alkoxyl group, an aryl group, an alkylaryl group, an aralkyl group, or a polyoxyalkylene group having 1 to 25 carbon atoms; X － is Cl － ,Br － , I － , HSO ４ －, H ２ P.O. ４ － , RCOO － , ROSO ２ － , or CO ３ ２－ It is. １ ~R ４ Two or three of these may form a ring structure together with P.

[0041] Examples of quaternary phosphonium salts include tetraphenylphosphonium chloride, benzyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, triphenylmethoxymethylphosphonium chloride, triphenylmethylcarbonylmethylphosphonium chloride, triphenylethoxycarbonylmethylphosphonium chloride, trioctylbenzylphosphonium chloride, trioctylmethylphosphonium chloride, trioctylethylphosphonium acetate, tetraoctylphosphonium chloride, trioctylethylphosphonium dimethylphosphate, etc. The quaternary phosphonium salt may be an equimolar compound of a polyhydroxy aromatic compound and a quaternary phosphonium compound, as described in JP-A-61-12741.

[0042] The quaternary ammonium salt has the formula: １ R ２ R ３ R ４ 〕 ＋ X － In the formula, R １ ~R ４ and X － is R in the above quaternary phosphonium salt １ ~R ４ and X － As the quaternary ammonium salt, for example, 1-alkylpyridinium salt, 5-aralkyl-1,5-diazabicyclo[4,3,0]-5-nonenium salt, 8-aralkyl-1,8-diazabicyclo[5,4,0]-7-undecenium salt, etc. may be used.

[0043] Examples of organic peroxides include dicumyl peroxide, cumene hydroperoxide, p-methane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, m-toluyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 1,3 ... butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, (1,1,3,3-tetramethylbutylperoxy)2-ethylhexanoate, tert-butylperoxybenzoate, tert-butylperoxylaurate, di(tert-butylperoxy)adipate, di(2-ethoxyethylperoxy)dicarbonate, bis-(4-tert-butylcyclohexylperoxy)dicarbonate, and the like.

[0044] The content of the organic peroxide may be 0.5 parts by mass or more, preferably 1 part by mass or more, and may be 10 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the peroxide-crosslinkable fluororubber.

[0045] From the viewpoint of improving the mechanical strength, compression set, etc. of the sealing member, organic peroxides are preferably used in combination with polyfunctional unsaturated compounds. Examples of polyfunctional unsaturated compounds include tri(meth)allyl isocyanurate, tri(meth)allyl cyanurate, triallyl trimellitate, N,N'-m-phenylene bismaleimide, diallyl phthalate, tris(diallylamine)-s-triazine, triallyl phosphite, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and 1,3-polybutadiene. Here, (meth)allyl means allyl or methallyl. (Meth)acrylate means acrylate or methacrylate.

[0046] The content of the polyfunctional unsaturated compound may be 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and may be 20 parts by mass or less, preferably 10 parts by mass or less, relative to 100 parts by mass of the peroxide-crosslinkable fluororubber.

[0047] The seal member 5 may further contain other components, such as an ashless friction modifier (described in detail below) and a reinforcing agent.

[0048] The rubber composition is obtained by kneading the above-mentioned components using a kneader, an open roll, or the like. The sealing member is obtained by forming the obtained rubber composition into a ribbon-shaped or pellet-shaped preform using an extruder or the like as needed, and then appropriately molding and vulcanizing the preform. When an inorganic filler and an ashless friction modifier are contained in the sealing member, the ashless friction modifier and the inorganic filler may be added separately to the rubber component, or the surface of the inorganic filler may be treated in advance to adsorb the ashless friction modifier, and the treated inorganic filler may then be added to the rubber component.

[0049] The lubricating oil is present on the sealed side O of the oil / seal lubrication system 1, and also between the circumferential surface of the rotating shaft 3 and the sliding surface 10 of the lip tip of the seal lip 7 of the seal member 5. The rotating shaft 3 comes into contact with the seal member 5 (the sliding surface 10 of the lip tip of the seal lip 7) via the lubricating oil, and moves relative to the seal member 5.

[0050] Lubricating oils contain a base oil. Examples of base oils include hydrocarbon oils and oxygenated oils. Examples of hydrocarbon oils include mineral oils, alkylbenzenes, alkylnaphthalenes, polyα-olefins, polybutenes, and ethylene-α-olefin copolymers. Examples of oxygenated oils include esters and ethers. Examples of esters include polyol esters and complex esters. Examples of ethers include polyalkylene glycols and polyvinyl ethers, diphenyl ethers, dimethyl siloxanes, and perfluoropolyethers.

[0051] The hydrocarbon oil is preferably mineral oil or isoparaffin. Examples of mineral oil include paraffinic mineral oil (normal paraffin, isoparaffin, etc.), naphthenic mineral oil, aromatic mineral oil, etc., obtained by refining a lubricating oil fraction obtained by atmospheric distillation and / or vacuum distillation of crude oil through a single or suitable combination of two or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. The isoparaffin may contain, as a main component, isoparaffin obtained by hydrocracking and / or hydroisomerization of a paraffin wax component obtained by the dewaxing process or Fischer-Tropsch synthesis.

[0052] The oxygenated oil is preferably a polyol ester, which is an ester of a polyhydric alcohol and a carboxylic acid, and preferably an ester of a polyhydric alcohol and a fatty acid.

[0053] The polyhydric alcohol constituting the polyol ester may be a polyhydric alcohol having 2 to 6 hydroxyl groups. The number of carbon atoms in the polyhydric alcohol may be 4 to 12. Examples of polyhydric alcohols include hindered alcohols such as neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, and dipentaerythritol. The polyhydric alcohol is preferably at least one selected from the group consisting of trimethylolpropane, pentaerythritol, and dipentaerythritol.

[0054] The fatty acid constituting the polyol ester may be a saturated fatty acid or an unsaturated fatty acid. In one embodiment, when the polyhydric alcohol is trimethylolpropane, the fatty acid preferably comprises an unsaturated fatty acid. In another embodiment, when the polyhydric alcohol is pentaerythritol or dipentaerythritol, the fatty acid preferably comprises a saturated fatty acid.

[0055] The number of carbon atoms of the unsaturated fatty acid may be 14 or more and 20 or less. Examples of the unsaturated fatty acid include physeteric acid, myristoleic acid, palmitoleic acid, heptadecenylene acid, petroselaidic acid, elaidic acid, oleic acid, and vaccenic acid. The unsaturated fatty acid preferably includes oleic acid.

[0056] The number of carbon atoms in the saturated fatty acid may be preferably 4 or more, and preferably 20 or less, more preferably 18 or less, and even more preferably 9 or less. Examples of saturated fatty acids include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, and icosanoic acid. These saturated fatty acids may be linear or branched.

[0057] In one embodiment, the complex ester may be a complex ester of a polyhydric alcohol, a polycarboxylic acid, and at least one selected from the group consisting of a monocarboxylic acid and a monohydric alcohol. Examples of the polyhydric alcohol constituting the complex ester may be the same as the examples of the polyhydric alcohol constituting the polyol ester described above. The polycarboxylic acid constituting the complex ester may be a dicarboxylic acid. The carbon number of the dicarboxylic acid may be 2 or more, preferably 4 or more, and may be 12 or less, preferably 10 or less. Examples of the polycarboxylic acid include succinic acid, adipic acid, azelaic acid, and sebacic acid.

[0058] The monocarboxylic acid constituting the complex ester may be a fatty acid. Examples of the fatty acid may be the same as the examples of the fatty acid constituting the polyol ester described above. The number of carbon atoms of the monohydric alcohol constituting the complex ester may be 2 or more, preferably 4 or more, and 20 or less, preferably 10 or less. Examples of the monohydric alcohol include ethanol, butanol, hexanol, octanol, nonanol, decanol, etc.

[0059] The base oils are classified into API base oil Group I (viscosity index of 80 or more but less than 120, sulfur content exceeding 0.03% by mass and / or saturated content less than 90% by mass; solvent refined base oil), Group II (viscosity index of 80 or more but less than 120, sulfur content of 0.03% by mass or less, and saturated content of 90% by mass or more: hydrotreated base oil), Group III (viscosity index of 120 or more, sulfur content of 0.03% by mass or less, and saturated content of 90% by mass or more: hydrocracked / hydroisomerized oil), Group IV (poly-α-olefin base oil), and Group V (base oil not belonging to any of Groups I to IV).

[0060] The base oil may contain, as a main component, at least one selected from the group consisting of base oils classified into any of these groups. The group may preferably be the group consisting of base oils classified into any of Group II, Group III, Group IV, and Group V, or may be the group consisting of base oils classified into Group III, Group IV, and Group V, or may be the group consisting of base oils classified into Group III or Group IV.

[0061] As these base oils, a base oil having a saturated content of 90 mass% or more, preferably 94 mass% or more, 97 mass% or more, or 99 mass% or more and an aromatic content of 10 mass% or less, preferably 6 mass% or less, 3 mass% or less, or 1 mass% or less may be used as a main component, and %C Ｐ is 60 or more, 70 or more, 75 or more, or 80 or more, % C Ｎ is 40 or less, 30 or less, or 25 or less, % C Ａ However, the %C may be 5 or less, 3 or less, 1 or less, or 0.1 or less as the main component. Ｐ , %C Ｎ , %C ＡThe "total of 100" refers to the weight ratio of the paraffinic carbon content, naphthenic carbon content, and aromatic carbon content to the total carbon content, respectively (determined in accordance with ASTM D 3238). The viscosity index of these base oils is preferably 80 or higher, and may be 90 or higher, 100 or higher, 120 or higher, 130 or higher, 140 or higher, or 150 or higher. Base oils classified into Group V include aromatic hydrocarbon base oils such as alkylbenzenes and alkylnaphthalenes, and oxygen-containing base oils such as esters and ethers, with ester-based base oils or ether-based base oils being preferred. The viscosity index of at least one oxygen-containing base oil selected from ester-based base oils and ether-based base oils is preferably 50 or higher, 80 or higher, and may be 90 or higher, 100 or higher, 120 or higher, 130 or higher, 140 or higher, or 150 or higher.

[0062] The kinematic viscosity of the base oil at 40°C is 3 mm ２ / s or more, 4mm ２ / s or more, or 5 mm ２ / s or more, and ２ / s or less, 300mm ２ / s or less, or 100 mm ２ The kinematic viscosity of the base oil at 100°C may be 1 mm / s or less. ２ / s or more or 2 mm ２ / s or more, and 100 mm ２ / s or less or 50 mm ２ The kinematic viscosity in this specification means a kinematic viscosity measured in accordance with JIS K2283:2000.

[0063] The content of the base oil may be 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % or more, or 90 mass % or more based on the total amount of the lubricating oil.

[0064] The lubricating oil may contain only a base oil, or may further contain additives in addition to the base oil, such as ashless friction modifiers (described in detail below), antiwear agents, extreme pressure agents, metal-based friction modifiers, antioxidants, acid scavengers, metal deactivators, viscosity index improvers, pour point depressants, detergent-dispersants, antifoaming agents, and thickeners.

[0065] The total content of the additives may be 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, based on the total amount of the lubricating oil, and may be 40 mass % or less, 20 mass % or less, 10 mass % or less, or 5 mass % or less.

[0066] In the oil / seal lubrication system described above, at least one of the seal member and the lubricating oil contains an ashless friction modifier. That is, in one embodiment, the seal member may contain an ashless friction modifier, and the lubricating oil may not contain an ashless friction modifier. In another embodiment, the lubricating oil may contain an ashless friction modifier, and the seal member may not contain an ashless friction modifier. In another embodiment, both the seal member and the lubricating oil may contain an ashless friction modifier. From the viewpoint of obtaining a particularly significant effect of reducing friction, it is preferable that both the seal member and the lubricating oil contain an ashless friction modifier. When both the seal member and the lubricating oil contain an ashless friction modifier, the ashless friction modifier in the seal member and the ashless friction modifier in the lubricating oil may be the same or different from each other.

[0067] The ashless friction modifier may be, for example, at least one selected from the group consisting of fatty acid ester compounds, phosphorus compounds, ether compounds, alcohol compounds, amide compounds, amine compounds, imide compounds, sulfur compounds, and phosphorus-sulfur compounds. From the viewpoint of enabling further reduction in friction, the ashless friction modifier may preferably be at least one selected from the group consisting of fatty acid ester compounds, phosphorus compounds, amide compounds, amine compounds, imide compounds, sulfur compounds, and phosphorus-sulfur compounds. These friction modifiers may be compounds having a hydrocarbon group and a polar group. Examples of the hydrocarbon group include linear hydrocarbon groups, aromatic hydrocarbon groups, and alicyclic hydrocarbon groups. The hydrocarbon group may have two or more carbon atoms and may have 400 or less, 200 or less, or 40 or less. The hydrocarbon group may be a saturated or unsaturated hydrocarbon group. Examples of the polar group include ester groups, carboxy groups, amine groups, amide groups, imide groups, and phosphate groups. These polar groups can be adsorbed to the surface of inorganic fillers.

[0068] When both the seal member and the lubricating oil contain an ashless friction modifier, the combination of the ashless friction modifier in the seal member and the ashless friction modifier in the lubricating oil may be combinations C1 to C81 shown in Table 1 below.

[0069] Among the above combinations, the combinations (C1 to C9, C10, C19, C28, C37, C46, ​​C55, C64, C73) in which at least one of the ashless friction modifiers in the seal member and the lubricating oil is a fatty acid ester-based compound are preferred, and the combination (C1) in which both the ashless friction modifier in the seal member and the ashless friction modifier in the lubricating oil are fatty acid ester-based compounds is more preferred.

[0070] The fatty acid ester compound is at least one selected from esters of fatty acids and monohydric alcohols or polyhydric alcohols, preferably esters of fatty acids and polyhydric alcohols. The fatty acid ester compound has a hydrocarbon group derived from a fatty acid or alcohol. The number of carbon atoms in the hydrocarbon group may be 2 or more, preferably 6 or more or 12 or more, and may be 40 or less, preferably 20 or less or 18 or less.

[0071] In one embodiment, the fatty acid ester compound may have the hydrocarbon group, an ester group, and a hydroxyl group (i.e., may be a partial ester of a fatty acid and a polyhydric alcohol). The fatty acid ester compound may contain 10% by mass or more of the partial ester of a fatty acid and a polyhydric alcohol as a main component (e.g., 50% by mass or more, preferably 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, and 100% by mass or less).

[0072] The number of carbon atoms in the fatty acid constituting the fatty acid ester-based compound may be 2 or more, preferably 6 or more, and may be 30 or less, preferably 20 or less. The fatty acid may more preferably include a saturated or unsaturated fatty acid having 12 to 18 carbon atoms, and may include at least one selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid.

[0073] The monohydric alcohol constituting the fatty acid ester compound may be an aliphatic alcohol. The carbon number of the aliphatic alcohol may be 2 or more, preferably 6 or more, and may be 30 or less, preferably 20 or less. More preferably, the monohydric alcohol may include a saturated or unsaturated aliphatic alcohol having 12 to 18 carbon atoms, and may include at least one selected from the group consisting of lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol.

[0074] The polyhydric alcohol constituting the fatty acid ester-based compound may have 2 to 6 hydroxyl groups. The number of carbon atoms in the polyhydric alcohol may be 2 or more, preferably 3 or more, and may be 12 or less, preferably 6 or less. The polyhydric alcohol may more preferably include a polyhydric alcohol having 3 to 6 carbon atoms and 2, 3, or 4 hydroxyl groups, and may include at least one selected from the group consisting of glycerin, sorbitan, neopentyl glycol, trimethylolpropane, and pentaerythritol.

[0075] Specific examples of these fatty acid ester compounds include fatty acid monoesters having a hydrocarbon group containing 12 to 18 carbon atoms, such as oleyl oleate and stearyl stearate. Other specific examples of fatty acid ester compounds include polyhydric alcohol fatty acid esters having a hydrocarbon group containing 12 to 18 carbon atoms, such as glycerin fatty acid esters, sorbitan fatty acid esters, neopentyl glycol fatty acid esters, trimethylolpropane fatty acid esters, and pentaerythritol fatty acid esters. These polyhydric alcohol fatty acid esters may be partial esters, and more specifically, may be glycerin monooleate, sorbitan monooleate, trimethylolpropane decanoate (main components: monoesters and diesters), pentaerythritol oleate (main components: monoesters, diesters, and triesters), etc. Other specific examples of fatty acid ester compounds include polymethacrylic acid esters having a hydrocarbon group containing 1 to 40 carbon atoms.

[0076] The phosphorus-based compound is a compound containing phosphorus as a constituent element (excluding compounds containing sulfur as a constituent element). Examples of the phosphorus-based compound include phosphites, orthophosphates, amine salts of acidic phosphates, hydrogen phosphites, phosphonates, and phosphinates. The phosphorus-based compound may have a hydrocarbon group. The number of carbon atoms in the hydrocarbon group in the phosphorus-based compound may be 1 or more, 6 or more, or 12 or more, and may be 30 or less, 20 or less, or 18 or less.

[0077] The phosphorus-based compound is preferably at least one selected from the group consisting of phosphites, orthophosphates, and amine salts of acidic phosphates.

[0078] Examples of the phosphite include dialkyl hydrogen phosphite, dialkenyl hydrogen phosphite, diaryl hydrogen phosphite, trialkyl phosphite, trialkenyl phosphite, and triaryl phosphite. The phosphite is preferably at least one selected from the group consisting of dialkenyl hydrogen phosphite and diaryl hydrogen phosphite.

[0079] Examples of alkyl groups in dialkyl hydrogen phosphites and trialkyl phosphites include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and didodecyl groups. Examples of alkenyl groups in dialkenyl hydrogen phosphites and trialkenyl phosphites include oleyl groups. Examples of aryl groups in diaryl hydrogen phosphites and triaryl phosphites include phenyl and cresyl groups.

[0080] Examples of orthophosphate esters include trialkyl phosphate, trialkenyl phosphate, and triaryl phosphate. Examples of alkyl groups in trialkyl phosphates include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, decyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. Examples of alkenyl groups in trialkenyl phosphates include oleyl groups. Examples of aryl groups in triaryl phosphates include phenyl, cresyl, ethylphenyl, butylphenyl, and xylenyl groups. The orthophosphate ester is preferably triaryl phosphate, and more preferably tricresyl phosphate.

[0081] Examples of the acidic phosphate ester in the amine salt of an acidic phosphate ester include monoalkyl acid phosphate, monoalkenyl acid phosphate, dialkyl acid phosphate, and dialkenyl acid phosphate.

[0082] Examples of the alkyl group in the monoalkyl acid phosphate and dialkyl acid phosphate include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group. Examples of the alkenyl group in the monoalkenyl acid phosphate and dialkenyl acid phosphate include an oleyl group.

[0083] Examples of the amine in the amine salt of an acidic phosphoric acid ester include mono-, di-, and tri-alkylamines. Examples of the alkyl group in these amines include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl groups.

[0084] An ether-based compound is a compound having a hydrocarbon group and an ether group. The number of carbon atoms in the hydrocarbon group may be 1 or more, 6 or more, or 12 or more, and may be 30 or less, 20 or less, or 18 or less. Examples of the ether-based compound include etherified products of polyhydric alcohols having a hydrocarbon group with 6 to 18 carbon atoms, such as glycerin oleyl ether, glycerin stearyl ether, glycerin 2-ethylhexyl ether, and glycerin hexyl ether; and etherified products of monohydric alcohols having a hydrocarbon group with 6 to 18 carbon atoms, such as dioctyl ether and diphenyl ether.

[0085] The alcohol-based compound is a compound having a hydrocarbon group and a hydroxyl group. The number of carbon atoms in the hydrocarbon group may be 1 or more, 6 or more, or 12 or more, and may be 30 or less, 20 or less, or 18 or less. Examples of the alcohol-based compound include alcohol-based compounds having a hydrocarbon group with a carbon number of 6 to 18, such as oleyl alcohol, lauryl alcohol, decyl alcohol, stearyl alcohol, cyclohexyl alcohol, and phenol.

[0086] Examples of amide compounds include oleoyl sarcosine, fatty acid amides, fatty acid monoamides such as oleyl oleic acid monoamide and stearyl oleic acid monoamide, fatty acid diamides such as ethylene bisstearic acid diamide and ethylene bisoleic acid diamide, etc. The number of carbon atoms in the hydrocarbon group in the amide compound may be 1 or more, 6 or more, or 12 or more, and may be 30 or less, 20 or less, or 18 or less.

[0087] Examples of amine compounds include alkylamines, alkenylamines, and alkylene oxide adducts thereof, and alkanolamines. The alkylamines may be monoalkylamines, dialkylamines, or trialkylamines. The alkenylamines may be monoalkenylamines, dialkenylamines, or trialkenylamines.

[0088] The number of carbon atoms in the hydrocarbon group in the alkylamine or alkenylamine may be 1 or more, 6 or more, or 12 or more, and may be 30 or less, 20 or less, or 18 or less. An example of an alkylamine is stearylamine. An example of an alkenylamine is oleylamine. Examples of alkanolamines include N,N-bis(2-hydroxyethyl)stearylamine, oleyldiethanolamine, etc. An example of an alkylene oxide adduct is an ethylene oxide adduct of an alkyl or alkenylamine.

[0089] Examples of imide compounds include alkyl or alkenyl succinimides and their boron adducts. Specific examples of these include succinimides having a hydrocarbon group with 30 or less carbon atoms, such as oleyl succinimide, and boron adducts thereof, such as polymeric poly(iso)butenyl succinimide and boric acid-modified products thereof. The number of carbon atoms in the hydrocarbon group in the imide compound may be 1 or more, 6 or more, or 12 or more, and 30 or less, 20 or less, or 18 or less. The average number of carbon atoms in the poly(iso)butenyl succinimide group may be 40 or more, 60 or more, or 80 or more, and 400 or less, 200 or less, or 150 or less.

[0090] The sulfur-based compound is a compound containing sulfur as a constituent element (excluding compounds containing phosphorus as a constituent element). Examples of the sulfur-based compound include sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiazoles, thiadiazoles, dithiocarbamates, and sulfides. The sulfur-based compound may have a hydrocarbon group. The number of carbon atoms in the hydrocarbon group in the sulfur-based compound may be 1 or more, 6 or more, and 30 or less, 20 or less, or 18 or less.

[0091] The sulfur-based compound is preferably a sulfide. The sulfide may be a monosulfide or a polysulfide. An example of the sulfide is a dialkyl sulfide. The dialkyl sulfide is preferably a dialkyl polysulfide. The number of carbon atoms in the alkyl group in the dialkyl sulfide (dialkyl polysulfide) may be 1 or more, preferably 4 or more or 6 or more, and may be 12 or less, preferably 10 or less. The sulfur-based compound may be a dithiocarbamate. A specific example thereof is a dialkyldithiocarbamate ester. The number of carbon atoms in the alkyl group in the dialkyldithiocarbamate may be 1 or more, preferably 4 or more or 6 or more, and may be 12 or less, preferably 10 or less.

[0092] Phosphorus-sulfur compounds are compounds containing phosphorus and sulfur as constituent elements. Examples of phosphorus-sulfur compounds include thiophosphates or derivatives thereof having 1 to 3, preferably 1 or 2, sulfur atoms. The number of carbon atoms in the hydrocarbon group in the phosphorus-sulfur compound may be 1 or more, 4 or more, or 6 or more, and may be 30 or less, 20 or less, or 18 or less. Examples of phosphorus-sulfur compounds include thiophosphates such as phosphorothioate and triphenylphosphorothioate, and dialkyldithiophosphorylated carboxylic acids or esters thereof, such as 3-diisobutoxyphosphinothioylsulfanyl-2-methylpropanoic acid or esters thereof.

[0093] The content of the friction modifier contained in the seal member 5 is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component in the seal member 5, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0094] The content of the friction modifier contained in the lubricating oil may be 0.01 mass % or more, 0.05 mass % or more, or 0.1 mass % or more, based on the total amount of the lubricating oil, and may be 10 mass % or less, 5 mass % or less, or 3 mass % or less.

[0095] By using the sealing member and lubricating oil described above, it is possible to reduce friction. For example, the friction coefficient measured using the sealing member and lubricating oil with an MTM tester may be 0.050 or less, 0.048 or less, 0.046 or less, 0.044 or less, 0.042 or less, or 0.040 or less. The friction coefficient is measured using the friction coefficient measurement method described in the examples.

[0096] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0097] (Preparation of sealing member S1) Using FKM (fluororubber, Technoflon (registered trademark) P757 manufactured by Solvay) as the rubber component, 75 parts by mass of iron (III) oxide (Brown #601 manufactured by Resinocolor Kogyo Co., Ltd.) as the inorganic filler, and 5 parts by mass of glycerin monooleate as an ashless friction modifier relative to 100 parts by mass of FKM, the mixture was kneaded using a kneader and an open roll, and molded at 180°C for 6 minutes to prepare a sealing member S1 of 40 x 40 x 2 mm.

[0098] (Preparation of Seal Member S2) A seal member S2 was prepared in the same manner as the seal member S1, except that no friction modifier was used.

[0099] (Preparation of Seal Member S3) A seal member S3 was prepared in the same manner as the seal member S2, except that wollastonite (Wollastnite 1250 manufactured by IMERYS) was used instead of iron (III) oxide.

[0100] (Preparation of Seal Member S4) A seal member S4 was prepared in the same manner as the seal member S2, except that carbon black (acetylene black, "Denka Black" manufactured by Denka Co., Ltd.) was used instead of iron (III) oxide.

[0101] (Preparation of Seal Member S5) A seal member S5 was prepared in the same manner as the seal member S1, except that iron (III) oxide and glycerin monooleate were not added.

[0102] (Lubricant L1) Base oil (Group III mineral oil, kinematic viscosity at 40°C: 32 mm ２ / s, kinematic viscosity at 100 ° C: 6 mm ２ / s, viscosity index: 134, sulfur content: less than 1 mass ppm, saturated content 99.5 mass% or more, aromatic content 0.5 mass% or less, %C Ｐ : 79.2, % C Ｎ : 20.8, % C Ａ 99% by mass of a lubricating oil (0.0) was mixed with 1% by mass of an ester compound (glycerin monooleate) as an ashless friction modifier to prepare lubricating oil L1.

[0103] (Lubricant L2) The same base oil as lubricant L1 (group III mineral oil, kinematic viscosity at 40 ° C: 32 mm ２ / s, kinematic viscosity at 100 ° C: 6 mm ２ / s, viscosity index: 134, sulfur content: less than 1 mass ppm, saturated content 99.5 mass% or more, aromatic content 0.5 mass% or less, %C Ｐ : 79.2, % C Ｎ : 20.8, % C Ａ : 0.0) was used as lubricating oil L2.

[0104] (Lubricant L3) Lubricant L3 was prepared in the same manner as lubricant L1, except that a phosphorus-based compound (oleyl acid phosphate amine salt) was used as the ashless friction modifier instead of the ester-based compound.

[0105] (Lubricant L4) Lubricant L4 was prepared in the same manner as lubricant L1, except that an ether-based compound (glycerin oleyl ether) was used as the ashless friction modifier instead of the ester-based compound.

[0106] (Lubricant L5) Lubricant L5 was prepared in the same manner as lubricant L1, except that an alcohol-based compound (oleyl alcohol) was used as the ashless friction modifier instead of the ester-based compound.

[0107] (Lubricant L6) Lubricant L6 was prepared in the same manner as lubricant L1, except that an amide compound (oleoyl sarcosine) was used as the ashless friction modifier instead of the ester compound.

[0108] In Examples 1 to 13 and Comparative Examples 1 and 2, one of the above seal members S1 to S4 and one of the lubricating oils L1 to L6 were selected, and the friction coefficients were measured for the combinations shown in Tables 2 and 3.

[0109] (Measurement of Friction Coefficient) The friction coefficient was measured under the following conditions using an MTM (MiniTraction Machine) testing machine (manufactured by PCS Instruments). Ball: 1 / 2 inch steel ball Disk: seal member (40 x 40 x 2 mm) Load: 10 N Sliding ratio: 200% (complete sliding) Average speed: 0.1 m / s Oil temperature: 25°C Measurements were carried out three times for each combination of seal member and lubricating oil, and the average value of the friction coefficient obtained from the three measurements was calculated. The results are shown in Tables 2 and 3.

[0110]

[0111]

[0112] In Tables 2 and 3, "(present)" means that an ashless friction modifier is included, and "(absent)" means that an ashless friction modifier is not included. The same applies to Table 4 below.

[0113] In addition, in Examples 14 to 16 and Comparative Example 5, one of the above-mentioned seal members S1 to S2, S5 and the following lubricating oils L7 to L8 was selected for each, and the friction coefficient was measured in the same manner as above for the combinations shown in Table 4. The results are shown in Table 4.

[0114] (Lubricant L7) Base oil (Group V ester (trimethylolpropane trioleate), kinematic viscosity at 40°C: 47.7 mm ２ / s, kinematic viscosity at 100 ° C: 9.5 mm ２ 99% by mass of a lubricating oil (100% by mass of glycerin monooleate, 1% by mass of ester compound) was mixed with 99% by mass of a lubricating oil (100% by mass of glycerin monooleate, 1% by mass of ester compound) as an ashless friction modifier to prepare lubricating oil L7.

[0115] (Lubricant L8) The same base oil as lubricant L7 (Group V ester (trimethylolpropane trioleate)), kinematic viscosity at 40 ° C: 47.7 mm ２ / s, kinematic viscosity at 100 ° C: 9.5 mm ２ / s, viscosity index: 189, sulfur content: less than 1 ppm by mass) was used as lubricating oil L8.

[0116]

[0117] 1...oil / seal lubrication system, 2...housing, 3...rotating shaft (sliding member), 4...reinforcing ring, 4a...cylindrical portion, 4b...inward flange portion, 5...sealing member, 6...peripheral seal portion, 7...seal lip, 8...dust lip, 9...sealed object side inclined surface, 10...sliding surface, 11...atmosphere side inclined surface, 14...garter spring, A...atmosphere side, O...sealed object side

Claims

1. An oil / seal lubrication system comprising: a seal member; and a sliding member that moves relative to the seal member and contacts the seal member via a lubricating oil, wherein the seal member contains an inorganic filler, and at least one of the seal member and the lubricating oil contains an ashless friction modifier.

2. The oil / seal lubrication system of claim 1, wherein both said seal member and said lubricating oil contain said ashless friction modifier.

3. The oil / seal lubrication system according to claim 1 or 2, wherein the inorganic filler is at least one selected from the group consisting of carbon black, metal oxides, metal hydroxides, and silicate minerals.

4. The oil / seal lubrication system according to claim 1 or 2, wherein the ashless friction modifier is at least one selected from the group consisting of fatty acid ester-based compounds, phosphorus-based compounds, ether-based compounds, alcohol-based compounds, amide-based compounds, amine-based compounds, imide-based compounds, sulfur-based compounds, and phosphorus-sulfur-based compounds.

5. The oil / seal lubrication system of claim 2, wherein the friction modifier in the seal member and the friction modifier in the lubricating oil are fatty acid ester-based compounds.

6. The oil / seal lubrication system according to claim 5, wherein the fatty acid ester compound contains a compound having a hydrocarbon group, an ester group, and a hydroxyl group.

7. The oil / seal lubrication system according to claim 1 or 2, wherein the lubricating oil contains at least one base oil selected from the group consisting of base oils classified into any one of Group I, Group II, Group III, Group IV and Group V of the API base oil classification.

8. The oil / seal lubrication system of claim 1 or 2, wherein the lubricating oil contains a base oil having a viscosity index of 80 or greater.

9. The lubricating oil is Ｐ is 60 or more, and % C Ａ 3. The oil / seal lubrication system of claim 1, comprising a base oil having a β-amino acid content of 5 or less.

10. The oil / seal lubrication system of claim 1 or 2, wherein the lubricating oil contains an oxygenated base oil.

11. The oil / seal lubrication system according to claim 1 or 2, wherein the coefficient of friction measured by an MTM testing machine using said seal member and said lubricating oil is 0.050 or less.

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