Lubricating oil composition
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- IDEMITSU KOSAN CO LTD
- Filing Date
- 2022-05-16
- Publication Date
- 2026-08-03
Smart Images
Figure 0007898929000001 
Figure 0007898929000002 
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Abstract
Description
Technical Field
[0001] The present invention relates to a lubricating oil composition, an electric drive unit, the use of the lubricating oil composition, and a method for producing the lubricating oil composition.
Background Art
[0002] Various devices such as engines, transmissions, reducers, compressors, and hydraulic devices have mechanisms such as torque converters, clutches, gear bearing mechanisms, oil pumps, and hydraulic control mechanisms. In these mechanisms, lubricating oil compositions are used, and lubricating oil compositions capable of meeting various requirements have been developed. For example, Patent Document 1 aims to provide a lubricating oil composition for a transmission that enhances high-temperature stability and shear stability and suppresses a decrease in low-temperature fluidity associated with long-term use, and contains a predetermined base oil and a predetermined amount of poly(meth)acrylate and satisfies predetermined parameters. A lubricating oil composition for a transmission is disclosed. In recent years, the development of electric drive units including motors, gearboxes, and inverters has been underway, and a lubricating oil composition suitable for this electric drive unit has been demanded. For example, Patent Document 2 aims to provide a lubricating oil composition having high extreme pressure properties, exhibiting high levels of durability and anti-wear properties, and showing a high volume ratio low efficiency, and contains a predetermined phosphite ester and a thiadiazole derivative. A lubricating oil composition suitable for an electric drive unit is disclosed.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] The lubricating oil composition used in the above-mentioned electric drive unit requires properties such as resistance to scuffing and resistance to copper corrosion. In other words, there is a need for a novel lubricating oil composition that has properties suitable for lubricating the various mechanisms incorporated within the device (e.g., resistance to scuffing and resistance to copper corrosion). [Means for solving the problem]
[0005] The inventors have found that by setting the kinematic viscosity of the lubricating oil composition within a predetermined range and including a predetermined phosphite ester, it is possible to provide a lubricating oil composition that exhibits excellent copper corrosion resistance even in long-term copper corrosion resistance tests (for example, 168 hours in the example described later) without using thiadiazole compounds and without reducing scuffing resistance. The present invention was completed based on the above findings. In other words, the present invention provides the following embodiments [1] to [9]. [1] A lubricating oil composition comprising a base oil (A) and a phosphorous acid ester (B) having at least one sulfur atom-containing group having 2 to 20 carbon atoms, with at least one -(S)x- group (x is an integer of 1 or more) between two adjacent carbon atoms in the structure of an alkyl group, The thiadiazole compound content is less than 0.05% by mass on a total basis of the lubricating oil composition. The kinematic viscosity of the lubricating oil composition at 100°C is 4.2 mm². 2 A lubricating oil composition with a viscosity of / s or higher. [2] The lubricating oil composition according to [1], wherein the phosphite ester compound (B) comprises at least one selected from the compound (B1) represented by the following general formula (b-1) and the compound (B2) represented by the following general formula (b-2). [ka] (In the formula, R B11 , R B21 and R B22 Each of the following independently represents an alkyl group having 1 to 19 carbon atoms, and each of the following independently represents an integer from 1 to 10: [3] The lubricating oil composition according to [1] or [2], wherein the content of the benzotriazole compound is less than 0.05% by mass on a basis of the total amount of the lubricating oil composition. [4] The lubricating oil composition according to any one of the claims [1] to [3], wherein the content of phosphite ester compound (B) is 0.15% by mass or more and less than 1.00% by mass on a basis of the total amount of the lubricating oil composition. [5] The lubricating oil composition according to any one of the items [1] to [4], wherein the base oil (A) is one or more selected from the group consisting of mineral oil, poly-α-olefin, isoparaffin, polyalkylene glycol, ester-based synthetic oil, ether-based synthetic oil, alkylbenzene-based synthetic oil, alkylnaphthalene-based synthetic oil, GTL, CTL, and BTL. [6] A lubricating oil composition according to any one of [1] to [5], used for lubricating an electric drive unit which includes at least a gearbox and an electric motor. An electric drive unit comprising a gearbox and an electric motor, filled with a lubricating oil composition described in any one of items [7][1] to [5]. Use of a lubricating oil composition, wherein the lubricating oil composition described in any one of items [8][1] to [5] is applied to the lubrication of an electric drive unit including at least a gearbox and an electric motor. A method for producing a lubricating oil composition according to any one of the items [9][1] to [5], A base oil (A) is blended with a phosphite ester compound (B) having at least one group with 2 to 19 carbon atoms in an alkyl group having 3 to 20 carbon atoms, in which one -CH2- group bonded to carbon atoms at both ends is replaced with an -S- group, The thiadiazole compound content is less than 0.05% by mass on a total basis of the lubricating oil composition, and the kinematic viscosity of the lubricating oil composition at 100°C is 4.2 mm². 2 A method for producing a lubricating oil composition that is prepared to have a value of / s or higher. [Effects of the Invention]
[0006] A preferred embodiment of the present invention is a lubricating oil composition having properties suitable for lubricating various mechanisms incorporated within a device, and a more specific embodiment of the lubricating oil composition can improve scuffing resistance and copper corrosion resistance in a balanced manner. Therefore, these lubricating oil compositions can be suitably used for lubricating, for example, an electric drive unit including at least a gearbox and an electric motor. [Modes for carrying out the invention]
[0007] The numerical ranges described herein can be any combination of upper and lower limits. For example, if the numerical range is described as "preferably 30 to 100, more preferably 40 to 80," then the ranges of "30 to 80" and "40 to 100" are also included in the numerical range described herein. Similarly, if the numerical range is described as "preferably 30 or more, more preferably 40 or more, and also preferably 100 or less, more preferably 80 or less," then the ranges of "30 to 80" and "40 to 100" are also included in the numerical range described herein. In addition, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more and 100 or less." Furthermore, in the provisions for upper and lower limits described herein, the numerical range from the lower limit to the upper limit can be defined by appropriately selecting and combining options from each set of choices as appropriate. In addition, several of the requirements described as preferred embodiments in this specification can be combined.
[0008] Furthermore, in this specification, kinematic viscosity and viscosity index refer to values measured or calculated in accordance with JIS K2283:2000. The phosphorus (P) content refers to the value measured in accordance with JPI-5S-38-92. The sulfur atom (S) content refers to the value measured in accordance with JIS K2541-6:2013.
[0009] [Composition of the lubricating oil composition] A lubricating oil composition according to one aspect of the present invention contains a base oil (A) (hereinafter also referred to as "component (A)") and a phosphite ester (B) (hereinafter also referred to as "component (B)"), wherein the content of a thiadiazole compound is less than 0.05% by mass on a basis of the total amount of the lubricating oil composition, and the kinematic viscosity of the lubricating oil composition at 100°C is 4.2 mm². 2 It is / s or greater. A lubricating oil composition according to another aspect of the present invention contains component (A) and component (B), wherein the content of the thiadiazole compound and the benzotriazole compound is less than 0.05% by mass on a basis of the total amount of the lubricating oil composition, and the kinematic viscosity of the lubricating oil composition at 100°C is 4.2 mm². 2 It is / s or greater. A lubricating oil composition according to one aspect of the present invention contains a base oil (A) along with a phosphite ester (B) having a predetermined structure, which allows for a well-balanced improvement in scuffing resistance and copper corrosion resistance even when the content of thiadiazole compounds (C) and benzotriazole compounds (D) is limited or substantially absent at a predetermined kinematic viscosity at 100°C. Because a lubricating oil composition according to one embodiment of the present invention has such properties, it can be suitably used for lubricating, for example, an electric drive unit including at least a gearbox and an electric motor.
[0010] In a lubricating oil composition according to one aspect of the present invention, the total content of components (A) and (B) is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and may also be 100% by mass or less, 99.5% by mass or less, 99.0% by mass or less, or 98.0% by mass or less. The details of each component contained in a lubricating oil composition according to one embodiment of the present invention will be described below.
[0011] <Ingredients (A): Base oil> In one aspect of the present invention, the base oil (A) used as component may be one or more selected from mineral oil and synthetic oil. Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; refined oils obtained by subjecting the distillates to one or more refining processes such as solvent delamination, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining (hydrocracking); mineral oils (GTL) obtained by isomerizing wax (GTL wax (Gas To Liquids WAX)) produced from natural gas by the Fischer-Tropsch process, etc.; mineral oils (CTL) obtained by isomerizing wax (CTL wax (Coal To Liquids WAX)) produced from coal by the Fischer-Tropsch process, etc.; and mineral oils (BTL) obtained by isomerizing wax (BTL wax (Biomass To Liquids WAX)) produced from biomass by the Fischer-Tropsch process, etc.).
[0012] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (e.g., 8-14 carbon olefin copolymers such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester-based synthetic oils such as polyol esters, dibasic acid esters, and phosphate esters; ether-based synthetic oils such as polyphenyl ethers; alkylbenzene-based synthetic oils; and alkylnaphthalene-based synthetic oils.
[0013] A lubricating oil composition according to one aspect of the present invention may contain a cycloalkane-based synthetic oil as a base oil, or may not contain it substantially. More specifically, in a lubricating oil composition according to one embodiment of the present invention, the content of cycloalkane-based synthetic oil may be, for example, less than 0.05% by mass, less than 0.03% by mass, less than 0.01% by mass, or less than 0.001% by mass, based on the total amount of component (A) contained in the lubricating oil composition. Examples of cycloalkane-based synthetic oils include naphthene-based synthetic oils containing a cyclohexane ring, a cycloheptane ring, a bicycloheptane ring, a bicyclooctane ring, or the like.
[0014] Component (A) used in one aspect of the present invention preferably includes one or more selected from mineral oils classified into Group II and Group III of the API (American Petroleum Institute) base oil category, and synthetic oils.
[0015] From the viewpoint of obtaining a lubricating oil composition capable of reducing seizure on the sliding member, the kinematic viscosity of component (A) used in one aspect of the present invention at 100 °C is preferably 2.5 mm 2 / s or more, more preferably 2.7 mm 2 / s or more, still more preferably 2.9 mm 2 / s or more, particularly preferably 3.1 mm 2 / s or more. Also, from the viewpoint of obtaining a lubricating oil composition having excellent cooling properties, it is preferably 8.0 mm 2 / s or less, more preferably 7.5 mm 2 / s or less, still more preferably 7.0 mm 2 / s or less, even more preferably 6.5 mm 2 / s or less, particularly preferably 6.0 mm 2 / s or less.
[0016] Also, the viscosity index of component (A) used in one aspect of the present invention is preferably 70 or more, more preferably 80 or more, still more preferably 90 or more, and particularly preferably 100 or more.
[0017] Also, in one aspect of the present invention, when a mixed oil obtained by combining two or more base oils is used as component (A), it is preferable that the kinematic viscosity and viscosity index of the mixed oil are within the above ranges. Therefore, a low-viscosity base oil and a high-viscosity base oil may be used in combination to prepare the mixed oil so that the kinematic viscosity and viscosity index are within the above ranges. In this case, the mixed oil may be a mixed oil obtained by combining two or more base oils whose kinematic viscosity and viscosity index at 100°C fall within the above-mentioned range, or it may be a mixed oil obtained by combining a base oil whose kinematic viscosity and viscosity index at 100°C fall within the above-mentioned range with a base oil whose kinematic viscosity and viscosity index at 100°C fall within the above-mentioned range with a base oil whose kinematic viscosity and viscosity index at 100°C fall within the above-mentioned range with a high-viscosity base oil, and the mixture may be adjusted to fall within the above-mentioned range. Even if the kinematic viscosity and viscosity index of component (A) at 100°C do not fall within the above-mentioned range, it is acceptable as long as the kinematic viscosity and viscosity index of the lubricating oil composition at 100°C fall within the range described later.
[0018] In a lubricating oil composition according to one aspect of the present invention, the content of component (A) is preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and may also be 99.9% by mass or less, 99.5% by mass or less, 99.0% by mass or less, 98.5% by mass or less, or 98.0% by mass or less.
[0019] <Component (B): Phosphite ester> A lubricating oil composition according to one aspect of the present invention contains, as component (B), a phosphorous ester having at least one sulfur atom-containing group having 2 to 20 carbon atoms, wherein at least one -(S)x- group (where x is an integer of 1 or more, preferably an integer from 1 to 10, more preferably an integer from 1 to 5, even more preferably an integer from 1 to 3, even more preferably 1 or 2, and particularly preferably 1) is substituted between two adjacent carbon atoms in the structure of an alkyl group. By including component (B) in a lubricating oil composition having a predetermined kinematic viscosity at 100°C, a lubricating oil composition with improved scuffing resistance and copper corrosion resistance can be obtained. In one embodiment of the present invention, component (B) may be used alone or in combination of two or more. Furthermore, component (B) may have one sulfur atom-containing group or two sulfur atom-containing groups within the same molecule. Phosphite esters having one sulfur atom-containing group (phosphorous monoester) and phosphorous esters having two sulfur atom-containing groups (phosphorous diester) may be used alone or in combination, but from the viewpoint of obtaining a lubricating oil composition with improved scuffing resistance, it is preferable to use phosphorous monoester and phosphorous diester in combination.
[0020] Furthermore, from the above viewpoint, the sulfur atom-containing group of the phosphite ester of component (B) is preferably a group represented by the following general formula (bi). [ka]
[0021] In the above general formula (bi), R b A is a linear or branched alkyl group, b R is a linear or branched alkylene group, b and A b The total number of carbon atoms is between 2 and 20. x is an integer greater than or equal to 1. * indicates the bond position with the phosphorus atom. R b and A b The total number of carbon atoms is 2 to 20, but from the viewpoint of creating a lubricating oil composition with improved scuffing resistance, it is preferably 3 to 18, more preferably 4 to 16, even more preferably 5 to 14, and even more preferably 6 to 12. x is an integer greater than or equal to 1, but from the viewpoint of providing a lubricating oil composition with improved copper corrosion resistance, it is preferably an integer from 1 to 10, more preferably an integer from 1 to 5, even more preferably an integer from 1 to 3, even more preferably 1 or 2, and particularly preferably 1.
[0022] R bThe number of carbon atoms in the alkyl group that can be selected is preferably 1 to 18, more preferably 1 to 16, even more preferably 3 to 14, even more preferably 4 to 12, and particularly preferably 6 to 10. R b Examples of alkyl groups that can be selected include methyl group, ethyl group, propyl group (n-propyl group, isopropyl group), butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), pentyl group, hexyl group, 2-ethylhexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group, and the like.
[0023] A b The number of carbon atoms in the alkylene group that can be selected is preferably 1 to 18, more preferably 1 to 16, more preferably 1 to 12, even more preferably 1 to 10, even more preferably 1 to 8, even more preferably 1 to 6, and particularly preferably 2 to 4. A b Examples of alkylene groups that can be selected include methylene groups, various propylene groups such as 1,1-ethylene groups, 1,2-ethylene groups, 1,3-propylene, 1,2-propylene, and 2,2-propylene, various butylene groups, various pentylene groups, various hexylene groups, various heptylene groups, various octylene groups, various nonylene groups, various desilene groups, various undecylene groups, various dodecylene groups, various tridecylene groups, various tetradecylene groups, various pentadecylene groups, various hexadecylene groups, various heptadecylene groups, and various octadecylene groups. Among these, A b The alkylene group that can be selected as is -(CH2) n A base represented by -(n is an integer from 1 to 19, preferably an integer from 1 to 16, more preferably an integer from 1 to 12, even more preferably an integer from 1 to 10, even more preferably an integer from 1 to 8, even more preferably an integer from 1 to 6, and particularly preferably an integer from 2 to 4) is preferred.
[0024] In one aspect of the present invention, the phosphite ester used as component (B) is a phosphite ester represented by the following general formula (b-1) or (b-2). [ka]
[0025] In the above formula, R B11 , R B21 , and R B22 Each of these is independently a linear or branched alkyl group, and the number of carbon atoms of each is independently preferably 1 to 18, more preferably 1 to 16, even more preferably 3 to 14, even more preferably 4 to 12, and particularly preferably 6 to 10. Furthermore, bB11, bB21, and bB22 are each independently integers between 1 and 10, preferably between 1 and 19, more preferably between 1 and 16, more preferably between 1 and 12, even more preferably between 1 and 10, even more preferably between 1 and 8, even more preferably between 1 and 6, and particularly preferably between 2 and 4.
[0026] R B11 , R B21 , and R B22 The alkyl group that can be selected is R in the general formula (bi). B1 It is similar to the alkyl group that can be selected, and the preferred number of carbon atoms and specific group are also the same.
[0027] In one embodiment of the present invention, the phosphite ester used as component (B) may be in the form of an amine salt. The amine that forms the amine salt is preferably a compound represented by the following general formula (b-3). This amine may be used alone or in combination of two or more types. [ka]
[0028] In the above general formula (b-3), r is an integer between 1 and 3, and is preferably 1. R xEach of these is independently an alkyl group having 6 to 18 carbon atoms, an alkenyl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a hydroxyalkyl group having 6 to 18 carbon atoms. Note, R x If multiple R x They may be the same, or they may be different from one another.
[0029] In a lubricating oil composition according to one embodiment of the present invention, the total content of component (B) is, based on the total amount (100% by mass) of the lubricating oil composition, preferably 0.15% by mass or more, more preferably 0.16% by mass or more, even more preferably 0.17% by mass or more, and particularly preferably 0.18% by mass or more, from the viewpoint of providing a lubricating oil composition with improved scuffing resistance, and from the viewpoint of providing a lubricating oil composition with improved copper corrosion resistance, preferably less than 1.00% by mass, more preferably 0.95% by mass or less, more preferably 0.90% by mass or less, even more preferably 0.85% by mass or less, even more preferably 0.80% by mass or less, even more preferably 0.75% by mass or less, even more preferably 0.70% by mass or less, even more preferably 0.65% by mass or less, even more preferably 0.60% by mass or less, even more preferably 0.55% by mass or less, even more preferably 0.50% by mass or less, even more preferably 0.45% by mass or less, and particularly preferably 0.40% by mass or less.
[0030] In a lubricating oil composition according to one aspect of the present invention, from the viewpoint of providing a lubricating oil composition with a good balance of scuffing resistance and copper corrosion resistance, it is preferable that component (B) contains both compound (B1) represented by the general formula (b-1) and compound (B2) represented by the general formula (b-2). In one embodiment of the present invention, the content ratio of compound (B1) to compound (B2) [(B1) / (B2)] is preferably 1 / 20 to 20 / 1 by mass, more preferably 1 / 18 to 18 / 1, even more preferably 1 / 16 to 16 / 1, even more preferably 1 / 14 to 14 / 1, even more preferably 1 / 12 to 12 / 1, and particularly preferably 1 / 10 to 10 / 1.
[0031] From the above viewpoint, in a lubricating oil composition according to one embodiment of the present invention, the content of component (B) in terms of phosphorus atoms is preferably 20 ppm by mass or more, more preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 120 ppm by mass or more, even more preferably 150 ppm by mass or more, even more preferably 170 ppm by mass or more, particularly preferably 200 ppm by mass or more, and also preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 400 ppm by mass or less.
[0032] From the above viewpoint, in a lubricating oil composition according to one embodiment of the present invention, the content of component (B) in terms of sulfur atoms is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 150 ppm by mass or more, even more preferably 170 ppm by mass or more, even more preferably 200 ppm by mass or more, particularly preferably 230 ppm by mass or more, and also preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 400 ppm by mass or less.
[0033] <Thiadianol compounds> One embodiment of the present invention limits the content of the thiadiazole compound to less than 0.05% by mass on a total basis of the lubricating oil composition. If the content of the thiadiazole compound is 0.05% by mass or more, the copper will turn black in long-term copper corrosion tests. One embodiment of the present invention limits the content of thiadiazole as described above, contains the above component (B), and adjusts the kinematic viscosity of the lubricating oil composition at 100°C to a predetermined range, thereby providing a lubricating oil composition that improves both scuffing resistance and copper corrosion resistance in a well-balanced manner.
[0034] In a lubricating oil composition according to one embodiment of the present invention, the content of the thiadiazole compound is less than 0.05% by mass, more preferably less than 0.03% by mass, even more preferably less than 0.01% by mass, and particularly preferably less than 0.001% by mass, based on the total amount of the lubricating oil composition. Furthermore, in one embodiment of the present invention, it is preferable that the lubricating oil composition is substantially free of thiadiazole compounds. Here, "substantially free of thiadiazole compounds" means excluding lubricating oil compositions that intentionally contain thiadiazole compounds, and does not exclude embodiments in which thiadiazole compounds are inevitably included, but it is preferable that the content of such thiadiazole compounds be as low as possible. Specifically, the content of thiadiazole compounds that are inevitably mixed in is less than 0.05% by mass, more preferably less than 0.03% by mass, even more preferably less than 0.01% by mass, and particularly preferably less than 0.001% by mass, based on the total amount of the lubricating oil composition.
[0035] In one embodiment of the present invention, the thiadiazole compound is a compound having a thiadiazole ring, and may be, for example, a compound represented by any of the following general formulas (c-1) to (c-4).
[0036] [ka]
[0037] In the above formula, R c1 and R c2 Each of these is independently a hydrocarbon group. m and n may each be an integer between 1 and 10, an integer between 1 and 6, an integer between 1 and 4, or an integer between 2 and 3, independently of each other.
[0038] R c1 and R c2Examples of hydrocarbon groups that can be selected include linear or branched alkyl groups such as methyl group, ethyl group, propyl group (n-propyl group, isopropyl group), butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), pentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, 1,1-dimethylheptyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group; ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, do Examples include linear or branched alkenyl groups such as decenyl, tridecenyl, tetradecenyl, and pentadecenyl groups; cycloalkyl groups that may have alkyl groups such as cyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, propylcyclohexyl, butylcyclohexyl, and heptylcyclohexyl groups; aryl groups such as phenyl, naphthyl, anthracenyl, biphenyl, and terphenyl groups; alkylaryl groups such as tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, and dimethylnaphthyl groups; and arylalkyl groups such as phenylmethyl, phenylethyl, and diphenylmethyl groups.
[0039] R c1 and R c2 The number of carbon atoms in the hydrocarbon group that can be selected may be 1 or more, 2 or more, 3 or more, or 5 or more, and may also be 30 or less, 20 or less, 16 or less, or 12 or less.
[0040] <benzotriazole compounds> In one embodiment of the present invention, the content of the benzotriazole compound is limited to less than 0.05% by mass on a total basis of the lubricating oil composition. In one embodiment of the present invention, while limiting the content of the benzotriazole compound as described above, the lubricating oil composition contains the above component (B) and adjusts the kinematic viscosity of the lubricating oil composition at 100°C to a predetermined range, thereby providing a lubricating oil composition that improves both scuffing resistance and copper corrosion resistance in a well-balanced manner.
[0041] In a lubricating oil composition according to one embodiment of the present invention, the content of the benzotriazole compound is less than 0.05% by mass, more preferably less than 0.03% by mass, even more preferably less than 0.01% by mass, and particularly preferably less than 0.001% by mass, based on the total amount of the lubricating oil composition. Furthermore, in one embodiment of the present invention, it is preferable that the lubricating oil composition is substantially free of benzotriazole compounds. Here, "substantially free of benzotriazole compounds" means excluding lubricating oil compositions that intentionally contain benzotriazole compounds, and does not exclude embodiments in which benzotriazole compounds are inevitably included, but it is preferable that the content of such benzotriazole compounds be as low as possible. Specifically, the content of benzotriazole compounds that are inevitably mixed in is less than 0.05% by mass, more preferably less than 0.03% by mass, even more preferably less than 0.01% by mass, and particularly preferably less than 0.001% by mass, based on the total amount of the lubricating oil composition.
[0042] In one embodiment of the present invention, the benzotriazole compound is a compound having a benzotriazole structure, and for example, a compound represented by the following general formula (d-0) is an example. [ka]
[0043] In the general formula (d-0), R D1 This is a hydrocarbon group or hydrogen atom which may contain at least one atom selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atoms. R D2 Each of these is a hydrocarbon group that may independently contain at least one atom selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atoms. z1 may be an integer between 0 and 4, an integer between 0 and 2, or an integer between 0 and 1.
[0044] Examples of the hydrocarbon group include alkyl groups, alkenyl groups, cycloalkyl groups, aryl groups, and groups formed by combining two or more of these. R D1 The number of carbon atoms in the hydrocarbon group that can be selected is, for example, 1 to 30, but may also be 3 to 26 or 6 to 20. R D2 The number of carbon atoms in the hydrocarbon group that can be selected is, for example, 1 to 20, but may be 1 to 12, 1 to 6, or 1 to 2.
[0045] Examples of the alkyl groups include methyl group, ethyl group, propyl group (n-propyl group, i-propyl group), butyl group (n-butyl group, i-butyl group, s-butyl group, t-butyl group), pentyl group (n-pentyl group, i-pentyl group, neopentyl group), hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and the like. The alkyl group may be a linear alkyl group or a branched alkyl group.
[0046] Examples of the aforementioned alkenyl group include ethenyl group (vinyl group), propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, octadecenyl group (oleyl group), and the like. The alkenyl group may be a linear alkenyl group or a branched alkenyl group.
[0047] Examples of the cycloalkyl group include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, and adamantyl group.
[0048] Examples of the aryl group include phenyl, naphthyl, anthryl, phenanthryl, biphenyl, terphenyl, and phenylnaphthyl groups.
[0049] <Various additives> A lubricating oil composition according to one aspect of the present invention may contain various additives as needed, as long as they do not impair the effects of the present invention. Examples of such additives include pour point depressants, viscosity index improvers, antioxidants, metal-based detergents, ashless dispersants, rust inhibitors, and defoamers. These lubricating oil additives may be used individually or in combination of two or more types.
[0050] The content of each of these various additives can be adjusted as appropriate within a range that does not impair the effects of the present invention, but on a basis of the total amount (100% by mass) of the lubricating oil composition, the content of each additive is usually 0.001 to 15% by mass, preferably 0.005 to 10% by mass, and more preferably 0.01 to 8% by mass for each additive independently.
[0051] [Pour point depressant] A lubricating oil composition according to one embodiment of the present invention may further contain a pour point depressant. The pour point depressant may be used alone or in combination of two or more types. Examples of pour point depressants used in one aspect of the present invention include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrenes. The mass-average molecular weight (Mw) of the pour point depressant used in one aspect of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, 45,000 or more, 50,000 or more, 55,000 or more, or 60,000 or more, or 150,000 or less, 120,000 or less, 100,000 or less, 90,000 or less, or 80,000 or less.
[0052] [Viscosity index improver] A lubricating oil composition according to one embodiment of the present invention may further contain a viscosity index improver. The viscosity index improver may be used alone or in combination of two or more types. Examples of viscosity index improvers used in one aspect of the present invention include polymers such as non-dispersible polymethacrylate, dispersed polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymer, etc.), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymer, styrene-isoprene copolymer, etc.). The weight-average molecular weight (Mw) of the viscosity index improver used in one aspect of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, or 20,000 or more, or 1,000,000 or less, 700,000 or less, 500,000 or less, 300,000 or less, 200,000 or less, 100,000 or less, or 50,000 or less.
[0053] [Antioxidant] A lubricating oil composition according to one embodiment of the present invention may further contain an antioxidant. The antioxidant may be used alone or in combination of two or more types. Examples of antioxidants used in one aspect of the present invention include amine-based antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; phenol-based antioxidants such as 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; and sulfur-based antioxidants such as phenothiazine, dioctadecyl sulfide, dilauryl-3,3'-thiodipropionate, and 2-mercaptobenzimidazole.
[0054] [Metal-based cleaning agent] A lubricating oil composition according to one aspect of the present invention may further contain a metal-based detergent. The metal-based detergent may be used alone or in combination of two or more types. Examples of metal-based detergents used in one aspect of the present invention include metal salts such as metal sulfonates, metal salicylates, and metal phenates. Furthermore, the metal atoms constituting the metal salt are preferably selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium.
[0055] In a lubricating oil composition according to one embodiment of the present invention, the metal-based detergent preferably contains one or more selected from calcium sulfonate, calcium salicylate, and calcium phenate, and more preferably contains calcium sulfonate. The calcium sulfonate content is preferably 50-100% by mass, more preferably 60-100% by mass, even more preferably 70-100% by mass, and even more preferably 80-100% by mass, based on the total amount (100% by mass) of metal-based detergents contained in the lubricating oil composition.
[0056] The base number of the metal-based detergent is preferably 0 to 600 mg KOH / g. However, in a lubricating oil composition according to one aspect of the present invention, the metal-based detergent is preferably an overbasic metal-based detergent with a base number of 100 mg KOH / g or more. The base number of the overbasic metal-based detergent is 100 mg KOH / g or more, preferably 150 to 500 mg KOH / g, and more preferably 200 to 450 mg KOH / g. In this specification, "base number" refers to the base number measured by the perchloric acid method in accordance with JIS K2501:2003 "Petroleum products and lubricating oils - Neutralization number test method" 7.
[0057] [Ashless Dispersant] A lubricating oil composition according to one aspect of the present invention may further contain an ashless dispersant from the viewpoint of improving the dispersibility of component (B). The ashless dispersant may be used alone or in combination of two or more types. In one aspect of the present invention, alkenyl succinimides are preferred as ashless dispersants, and examples include alkenyl succinic acid bisimide represented by the following general formula (e-1), alkenyl succinic acid monoimide represented by the following general formula (e-2), and the like.
[0058] [ka]
[0059] In the above general formulas (e-1) and (e-2), R E1 , R E2 and R E3 Each of these is an alkenyl group having a mass-average molecular weight (Mw) of 500 to 3000 (preferably 900 to 2500). R E1 , R E2 and R E3 Examples of the alkenyl group that can be selected include polybutenyl group, polyisobutenyl group, ethylene-propylene copolymer, and among these, polybutenyl group or polyisobutenyl group is preferred. A E1 , A E2 and A E3 These are, independently, alkylene groups having 2 to 5 carbon atoms. e1 is an integer from 0 to 10, preferably an integer from 1 to 4, more preferably 2 or 3. e2 is an integer from 1 to 10, preferably from 2 to 5, more preferably 3 or 4.
[0060] Furthermore, the compound represented by the general formula (e-1) or (e-2) may be a modified alkenyl succinimide obtained by reacting it with one or more selected from boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids.
[0061] [Rust inhibitor] A lubricating oil composition according to one aspect of the present invention may further contain a rust inhibitor. The rust inhibitor may be used alone or in combination of two or more types. Examples of rust inhibitors used in one aspect of the present invention include fatty acids, alkenyl succinate half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers, and the like.
[0062] [Antifoaming agent] A lubricating oil composition according to one embodiment of the present invention may further contain an antifoaming agent. The antifoaming agent may be used alone or in combination of two or more types. Examples of defoaming agents used in one aspect of the present invention include alkyl silicone-based defoaming agents, fluorosilicone-based defoaming agents, and fluoroalkyl ether-based defoaming agents.
[0063] <Method for producing a lubricating oil composition> A method for producing a lubricating oil composition according to one aspect of the present invention is a step of blending component (B) with component (A), and a step of the kinematic viscosity of the lubricating oil composition at 100°C being 4.2 mm 2 The method includes a step of preparing the lubricating oil composition to be 1 / s or more. Furthermore, the method for producing a lubricating oil composition according to one embodiment of the present invention does not include a step of blending a thiadiazole compound. The method for producing a lubricating oil composition according to another embodiment of the present invention does not include a step of blending a benzotriazole compound. The lubricating oil composition according to yet another embodiment of the present invention does not include a step of blending a thiadiazole compound and a benzotriazole compound. A method for producing a lubricating oil composition according to one aspect of the present invention preferably includes a step of blending other additives as needed. The preferred compounds and their proportions for component (A), component (B), and various additives are as described above. Furthermore, it is preferable that additives such as viscosity index improvers, pour point depressants, and defoamers be added in a state where they are dissolved in the diluted oil.
[0064] [Properties of the lubricating oil composition] The kinematic viscosity of a lubricating oil composition according to one embodiment of the present invention at 100°C is preferably 4.2 mm, from the viewpoint of providing a lubricating oil composition with improved scuffing resistance. 2 / s or more, more preferably 4.3 mm 2 / s or more, more preferably 4.4 mm 2 From the viewpoint of providing a lubricating oil composition that is 1 / s or more and also has improved cooling performance, a ratio of 8.0 mm is preferred. 2 / s or less, more preferably 7.5 mm 2 / s or less, more preferably 7.0 mm 2 / s or less, more preferably 6.5 mm 2 / s or less, particularly preferably 6.0 mm 2 It is less than or equal to / s.
[0065] The viscosity index of the lubricating oil composition according to one embodiment of the present invention is preferably 90 or higher, more preferably 100 or higher, even more preferably 110 or higher, even more preferably 120 or higher, and particularly preferably 130 or higher.
[0066] [Uses of lubricating oil compositions] A lubricating oil composition according to one preferred embodiment of the present invention can improve both scuffing resistance and copper corrosion resistance in a well-balanced manner. Considering these characteristics, a lubricating oil composition according to one aspect of the present invention can be suitably used for lubrication in mechanisms such as torque converters, wet clutches, gear bearing mechanisms, oil pumps, and hydraulic control mechanisms incorporated into various devices such as engines, transmissions, reducers, compressors, and hydraulic systems. Among these, the lubricating oil composition according to one embodiment of the present invention is preferably used for lubricating various mechanisms of an electric drive unit, which includes at least a gearbox and an electric motor. The electric drive unit is installed in fuel cell vehicles, electric vehicles, and hybrid vehicles. A lubricating oil composition according to one aspect of the present invention, when applied to an electric drive unit, plays a role in cooling the electric motor and lubricating the gearbox. In particular, the lubricating oil composition according to one aspect of the present invention has excellent scuffing resistance and copper corrosion resistance, thereby improving the lubrication of the gearbox, and also has the characteristic of preventing corrosion of copper-based components constituting the electric motor when used for cooling the electric motor due to its excellent copper corrosion resistance.
[0067] Furthermore, considering the above-mentioned properties of a lubricating oil composition according to one embodiment of the present invention, the present invention may also provide the following [1] and [2]. [1] An electric drive unit comprising at least a gearbox and an electric motor, filled with the lubricating oil composition according to one embodiment of the present invention described above. [2] Use of a lubricating oil composition, wherein the lubricating oil composition according to one embodiment of the present invention described above is applied to an electric drive unit including at least a gearbox and an electric motor. Preferred embodiments of the lubricating oil compositions described in [1] and [2] above are as stated above. [Examples]
[0068] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples. The methods for measuring various physical properties are as follows.
[0069] (1)Kinematic viscosity, viscosity index Measurements and calculations were performed in accordance with JIS K2283:2000. (2) Content of phosphorus atoms Measurements were taken in accordance with JPI-5S-38-92. (3) Sulfur atom content Measurements were taken in accordance with JIS K2541-6:2013.
[0070] Examples 1-3, Comparative Examples 1-5 Components (A), (B) and other additives shown in Table 2 were added in the amounts shown in Table 1 and thoroughly mixed to prepare each lubricating oil composition. Details of each component used in the preparation of the lubricating oil composition are as follows. Note that none of the lubricating oil compositions in Examples 1 to 3 contained benzotriazole compounds.
[0071] <Ingredient (A)> • "Mineral oil (a1)": 70N mineral oil classified as Group II in the API base oil category, kinematic viscosity at 100°C = 3.1 mm² 2 / s, viscosity index=109. • "Mineral oil (a2)": 100N mineral oil classified as Group III in the API base oil category, kinematic viscosity at 100°C = 4.2 mm² 2 / s, viscosity index=122.
[0072] <Ingredient (B)> • "Phosphite ester (b)": R in the general formula (b-1) above B11 is an n-octyl group (-C8H 17 ), bB11 is 2(1,2-ethylene group (-C2H4-)), and the compound corresponding to component (B1) is the compound represented by the formula (b-1-1) below, and the R in the general formula (b-2) B11 , R B22 is an n-octyl group (-C8H 17 A mixture of sulfur atom-containing phosphite ester compounds obtained by mixing a compound corresponding to component (B2) (a compound represented by the formula (b-2-1) below), where bB11 and bB22 are 2 (1,2-ethylene groups (-C2H4-)), in a mass ratio of component (B1) / component (B2) = 9 / 1. Sulfur atom content = 10.7% by mass, phosphorus atom content = 10% by mass. <Other additives besides components (A) and (B)> • Extreme pressure agent: Thiadianazole (2,5-bis(1,1-dimethylheptyldithio)-1,3,4-thiadiazole, in the above general formula (c-1), m=n=2, R C1 and R C2 Thiadiazole (a compound represented by the following formula (c-1-1)) is a 1,1-dimethylheptyl group. [ka]
[0073] • Extreme pressure agent: Tritril phosphate. • Viscosity index improver: Polymethacrylate-based viscosity index improver (content in terms of resin content: 0.13% by mass). • "Additive mixture": An additive mixture prepared by mixing antioxidants, metal-based detergents, ashless dispersants, pour point depressants, and defoamers, and diluting them with 70N hydrocracking mineral oil.
[0074] The kinematic viscosity and viscosity index of the prepared lubricating oil compositions were measured or calculated, and the following tests were performed. The results are shown in Table 1.
[0075] (1) FZG scuffing test (A10 / 16.6R / 90) In accordance with ASTM D5182, using an A10 type gear, the load was gradually increased according to the specifications under conditions of a sample oil temperature of 90°C, a rotational speed of 2900 rpm, and an operating time of approximately 7.5 minutes. The load stage at which scuffing occurred was determined. A higher value for this stage indicates a lubricating oil composition with superior resistance to scuffing.
[0076] (2) Copper corrosion resistance test In accordance with the testing method of JIS K2513 "Test Method for Corrosion of Copper Plates in Petroleum Products," a copper plate corrosion test was conducted under conditions of a test temperature of 150°C and a test duration of 168 hours. The discoloration of the copper plate was observed, and the resistance to copper corrosion in the liquid phase was evaluated based on "Table 1 Classification of Corrosion According to Standards for Copper Plate Corrosion" of JIS K2513, as shown in Table 1 below. In Table 2, the discoloration is indicated by a "discoloration number (subdivision symbol)," where a smaller number indicates lower resistance to copper corrosion, and the degree of corrosion progression is indicated alphabetically.
[0077] [Table 1]
[0078] [Table 2]
[0079] Table 2 shows that the lubricating oil compositions prepared in Examples 1-3 exhibited excellent resistance to both scuffing and copper corrosion. On the other hand, Comparative Examples 1, 2, and 5 showed good resistance to copper corrosion but poor resistance to scuffing. Comparative Examples 3 and 4 also showed good resistance to scuffing but poor resistance to copper corrosion.
Claims
1. A lubricating oil composition comprising a base oil (A) and a phosphorous acid ester (B) having at least one sulfur atom-containing group having 2 to 20 carbon atoms, with at least one -(S)x- group (x is an integer of 1 or more) between two adjacent carbon atoms in the structure of an alkyl group, The thiadiazole compound content is less than 0.001% by mass on a total basis of the lubricating oil composition. The kinematic viscosity of the lubricating oil composition at 100°C is 4.4 mm. ２ / s or greater, A lubricating oil composition comprising a phosphite ester (B) containing a compound (B1) represented by the following general formula (b-1) and a compound (B2) represented by the following general formula (b-2). 【Chemistry 1】 (In the formula, R B11, R B21, and R B22 each independently represent an alkyl group having 1 to 19 carbon atoms, and b B11, b B21, and b B22 each independently represent an integer from 1 to 10.)
2. The lubricating oil composition according to claim 1, wherein the content of the benzotriazole compound is less than 0.05% by mass on a basis of the total amount of the lubricating oil composition.
3. The lubricating oil composition according to claim 1, wherein the content of phosphite ester (B) is 0.15% by mass or more and less than 1.00% by mass on a basis of the total amount of the lubricating oil composition.
4. The lubricating oil composition according to claim 1, wherein the base oil (A) is one or more selected from the group consisting of mineral oil, poly-α-olefin, isoparaffin, polyalkylene glycol, ester-based synthetic oil, ether-based synthetic oil, alkylbenzene-based synthetic oil, alkylnaphthalene-based synthetic oil, GTL, CTL, and BTL.
5. A lubricating oil composition according to any one of claims 1 to 4, used for lubricating an electric drive unit which includes at least a gearbox and an electric motor.
6. An electric drive unit comprising a gearbox and an electric motor, filled with the lubricating oil composition according to any one of claims 1 to 4.
7. Use of a lubricating oil composition, wherein the lubricating oil composition according to any one of claims 1 to 4 is applied to the lubrication of an electric drive unit including at least a gearbox and an electric motor.
8. A method for producing a lubricating oil composition according to any one of claims 1 to 4, A base oil (A) is blended with a phosphorous acid ester (B) having at least one sulfur atom-containing group having 2 to 20 carbon atoms, with at least one -(S)x- group (x is an integer of 1 or more) between two adjacent carbon atoms in the alkyl group structure, The thiadiazole compound content is less than 0.001% by mass on a total basis of the lubricating oil composition, and the kinematic viscosity of the lubricating oil composition at 100°C is 4.4 mm². ２ Prepare it so that it is 1 / s or more, A method for producing a lubricating oil composition, wherein the phosphite ester (B) comprises a compound (B1) represented by the following general formula (b-1) and a compound (B2) represented by the following general formula (b-2). 【Chemistry 2】 (In the formula, R B11, R B21, and R B22 each independently represent an alkyl group having 1 to 19 carbon atoms, and b B11, b B21, and b B22 each independently represent an integer from 1 to 10.)