Lubricating oil composition and method for producing the same

Abstract

To provide a lubricant composition that can exhibit excellent wear resistance in an internal-combustion engine and a high friction coefficient in a wet clutch even when the content of phosphorus atoms derived from an anti-wear agent is reduced.SOLUTION: Provided are: a lubricant composition that is for use in an internal-combustion engine and that contains a base oil (A), at least one imide compound (B) selected from monoimide succinates (B1) represented by general formula (b-1) and bisimide succinates (B2) represented by general formula (b-2), at least one metal-based cleanser (C) selected from metal sulfonates (C1) having a branched alkyl group and metal phenates (C2) having a branched alkyl group, and zinc dithiophosphate (D), wherein the content of phosphorus atoms derived from the component (D) is less than 800 ppm by mass with respect to the total amount of the lubricant composition; and a production method for the lubricant composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a lubricating oil composition and a method for producing the same.

Background Art

[0002] For a system that lubricates the engine lubricating oil and the power transmission lubricating oil of a two-wheeled vehicle equipped with a wet clutch with the same oil, in addition to the performance required for the engine lubricating oil, it is also necessary to have the performance as the power transmission lubricating oil. Specifically, for engine lubricating oil, various characteristics such as wear resistance, detergency, heat resistance, oxidation stability, low oil consumption, and low frictional loss are required. On the other hand, in order to improve the fuel efficiency performance of power transmission devices such as transmissions, an improvement in power transmission efficiency and a reduction in size and weight are required. In particular, from the viewpoints of ensuring clutch capacity and reducing the weight of the clutch, it is required to increase the friction coefficient between the clutch disk and the clutch plate.

[0003] Patent Document 1 discloses a lubricating oil composition for internal combustion engines that is excellent in increasing the friction coefficient for wet clutches, together with the required performance for engine systems, and contains (a) zinc dialkyldithiophosphate and (b) a boron-containing ashless dispersant, and the lubricating oil composition for internal combustion engines in which the phosphorus amount is limited to a specific range. Patent Document 2 discloses a lubricating oil composition that can achieve both a high clutch capacity and a long shudder prevention life, and contains a succinimide having an alkenyl group or an alkyl group, a primary amine having a hydrocarbon group with 12 or more and 24 or less carbon atoms, a fatty acid amide compound, and a specific amide compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as a method for improving the anti-wear property of lubricating oil, a method of adding an anti-wear agent containing a phosphorus atom such as zinc dithiophosphate is widely applied. However, it has been found that phosphorus atoms poison exhaust gas catalysts such as platinum installed to remove harmful substances in exhaust gas of automobiles and the like. In recent years, from the viewpoint of global environmental protection, exhaust gas regulations have been becoming increasingly strict, and measures to suppress poisoning of the exhaust gas catalyst by reducing the phosphorus atom content in engine lubricating oil are required. The lubricating oil compositions described in Patent Documents 1 and 2 have not been sufficiently studied from the viewpoint of exhibiting excellent anti-wear property in internal combustion engines and a high clutch friction coefficient even when the content of phosphorus atoms derived from the anti-wear agent is reduced (specifically, when the phosphorus atom content derived from the anti-wear agent is less than 800 mass ppm based on the total amount of the lubricating oil composition), and improvement is desired in these performances.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a lubricating oil composition and a method for producing the same that can exhibit excellent anti-wear property in an internal combustion engine and a high friction coefficient in a wet clutch even when the phosphorus atom content derived from the anti-wear agent is reduced.

Means for Solving the Problems

[0007] The present inventors have found that a lubricating oil composition containing a base oil, an imide compound having a specific structure, a metal-based detergent having a specific structure, and zinc dithiophosphate, and a method for producing the same can solve the above problems, and have completed the present invention. That is, the present invention provides the following [1] and [2]. [1] A base oil (A), An imide compound (B) which is at least one selected from a succinic monoimide (B1) represented by the following general formula (b-1) and a succinic bisimide (B2) represented by the following general formula (b-2), A metal detergent (C) which is at least one selected from a metal sulfonate (C1) having a branched alkyl group and a metal phenate (C2) having a branched alkyl group, Zinc dithiophosphate (D), A lubricating oil composition containing, The content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition, and the lubricating oil composition is used for an internal combustion engine. [Chemical formula] 〔In the above general formulas (b-1) and (b-2), R A , R A1 and R A2 are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 4000. R B , R B1 and R B2 are each independently an alkylene group having 2 to 5 carbon atoms. R C is an alkyl group having 1 to 10 carbon atoms, or a group represented by -(AO) n -H (wherein A is an alkylene group having 2 to 4 carbon atoms and n represents an integer of 1 to 10). x1 is an integer of 1 to 10, and x2 is an integer of 1 to 10.〕 [2]Base oil (A), An imide compound (B) which is at least one selected from a succinic monoimide (B1) represented by the following general formula (b-1) and a succinic bisimide (B2) represented by the following general formula (b-2), A metal detergent (C) which is at least one selected from a metal sulfonate (C1) having a branched alkyl group and a metal phenate (C2) having a branched alkyl group, Zinc dithiophosphate (D), A method for producing a lubricating oil composition by mixing, A method for producing a lubricating oil composition for an internal combustion engine, wherein the content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition.

Chemical formula

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a lubricating oil composition and a method for producing the same, which can exhibit excellent anti-wear properties in an internal combustion engine and a high friction coefficient in a wet clutch even when the phosphorus atom content derived from the anti-wear agent is reduced.

Modes for Carrying Out the Invention

[0009] In this specification, for preferred numerical ranges (for example, ranges such as content), the lower limit value and the upper limit value described stepwise can be combined independently of each other. For example, from the description "preferably 10 to 90, more preferably 30 to 60", it is also possible to combine the "preferred lower limit value (10)" and the "more preferred upper limit value (60)" to obtain "10 to 60". Similarly, in this specification, the numerical values of "above", "below", "less than", and "exceeding" regarding the description of numerical ranges are numerical values that can be arbitrarily combined. In the following description, "wear resistance" means wear resistance in an internal combustion engine, and "clutch friction characteristics" means the property of exhibiting a high friction coefficient with respect to a wet clutch.

[0010] In this specification, the contents of phosphorus atoms, calcium atoms, and molybdenum atoms mean the values measured in accordance with JPI-5S-38-03. Also, the content of nitrogen atoms means the value measured in accordance with JIS K 2609.

[0011] [Lubricating oil composition] The lubricating oil composition of the present embodiment includes a base oil (A) and an imide compound (B) which is one or more selected from succinimide (B1) represented by the above general formula (b-1) and succinimide (B2) represented by the above general formula (b-2), a metal detergent (C) which is one or more selected from a metal sulfonate (C1) having a branched-chain alkyl group and a metal phenate (C2) having a branched-chain alkyl group, zinc dithiophosphate (D), and is a lubricating oil composition containing a lubricating oil composition for an internal combustion engine, in which the content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the above lubricating oil composition. Hereinafter, each component contained in the lubricating oil composition of the present embodiment will be described.

[0012] [Base oil (A)] As the base oil (A) contained in the lubricating oil composition of the present embodiment, those containing one or more selected from mineral oils and synthetic oils may be used.

[0013] Examples of mineral oils include atmospheric residue obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate-base crude oil, and naphthenic crude oil; distillate oil obtained by vacuum distillation of these atmospheric residues; and mineral oils obtained by subjecting the distillate oil to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0014] Examples of the synthetic oil include poly-α-olefins such as α-olefin homopolymers and α-olefin copolymers (e.g., α-olefin copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers); isoparaffins; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenyl ethers; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes; and GTL base oils obtained by isomerizing waxes (GTL waxes (Gas To Liquids WAX)) produced from natural gas by the Fischer-Tropsch method or the like.

[0015] As the base oil used in this embodiment, base oils classified into Group 2 and Group 3 of the API (American Petroleum Institute) base oil category are preferable, and base oils classified into Group 2 are more preferable.

[0016] The base oil (A) may be used alone or in combination of two or more kinds of mineral oils, or may be used alone or in combination of two or more kinds of synthetic oils. Further, one or more kinds of mineral oils and one or more kinds of synthetic oils may be used in combination.

[0017] There are no particular restrictions on the kinematic viscosity and viscosity index of the base oil (A), but from the viewpoint of making the wear resistance of the lubricating oil composition better, the kinematic viscosity and viscosity index are preferably in the following ranges. The kinematic viscosity of the base oil (A) at 100 °C is preferably 4.0 to 20.0 mm 2 / s, more preferably 4.5 to 15.0 mm 2 / s, still more preferably 5.0 to 11.0 mm 2 / s. The viscosity index of the base oil (A) is preferably 80 or more, more preferably 90 or more, still more preferably 100 or more, and even more preferably 105 or more. In this specification, the kinematic viscosity and viscosity index mean values measured or calculated in accordance with JIS K 2283:2000. Further, when the base oil (A) is a mixed base oil containing two or more base oils, the kinematic viscosity and viscosity index of the mixed base oil may be within the above ranges.

[0018] In the lubricating oil composition of the present embodiment, the content of the base oil (A) is not particularly limited. However, from the viewpoint of making the anti-wear property better, based on the total amount (100% by mass) of the lubricating oil composition, it is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, and still more preferably 80 to 97% by mass.

[0019] <Imide compound (B)> The imide compound (B) is at least one selected from a succinimide (B1) represented by the following general formula (b-1) and a succinimide (B2) represented by the following general formula (b-2). Component (B) is classified as an ashless dispersant in the lubricating oil composition of the present embodiment. Component (B) is a succinimide or succinimide compound produced from a polyamine compound, and at least a part of the active amine hydrogen contained therein is a substituent such as an alkyl group (R in the following general formulas (b-1) and (b-2)) c ) having a substituted structure. The lubricating oil composition of the present embodiment can exhibit excellent anti-wear property and clutch friction characteristics by using component (B). As one of the reasons, in the succinimide having active amine hydrogen, the active amine hydrogen coordinates with zinc dithiophosphate (D), suppressing the anti-wear property improvement effect of component (D). However, it is considered that the coordination is suppressed by substituting the active amine hydrogen with a low-reactive substituent, and the original anti-wear property improvement effect of component (D) is achieved. At the same time, although the detailed mechanism is unclear, when component (B) is used in combination with a metal detergent (C) described later, it exhibits a synergistic effect of significantly improving the anti-wear property while maintaining good clutch friction characteristics.

[0020]

Chemical formula

[0021] In the above general formulas (b-1) and (b-2), R A , R A1 and R A2 are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 4000. Examples of the alkenyl group include a polybutenyl group, a polyisobutenyl group, an ethylene-propylene copolymer, etc. Among these, a polybutenyl group or a polyisobutenyl group is preferable. The mass average molecular weight (Mw) of the alkenyl group is 500 to 4000, preferably 900 to 3000, more preferably 1300 to 2500, and still more preferably 1800 to 2400. In the present invention, the mass average molecular weight (Mw) of the alkenyl group can be measured, for example, for the polyolefin which is the production source of the alkenyl group, using a GPC apparatus (HLC-8220 type) manufactured by Tosoh Corporation, attached with columns (2 TSKgel GMH-XL and 1 G2000H-XL) manufactured by Tosoh Corporation, detector: refractive index detector, measurement temperature: 40 °C, mobile phase: tetrahydrofuran, flow rate: 1.0 ml / min, concentration 0.5 mg / ml, and evaluated as the mass average molecular weight (Mw) in terms of standard polystyrene. As another method, after subtracting the theoretical molecular weight of the structure corresponding to other than the alkenyl group from the mass average molecular weight of the component (B) measured by the same measurement method as above, the value obtained by dividing by the number of alkenyl groups contained in one molecule can also be determined as the mass average molecular weight (Mw) of the alkenyl group.

[0022] R B , R B1 and R B2 are each independently an alkylene group having 2 to 5 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, various butylene groups, various pentylene groups, etc. In the present specification, "various" in various butylene groups, etc. means those including linear, branched, and their isomers.

[0023] RC is an alkyl group having 1 to 10 carbon atoms, or -(AO) n -H (wherein A is an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 10). Examples of the alkyl group include linear or branched alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, 1,1-dimethylhexyl group, 2-ethylhexyl group, nonyl group, 1,1-dimethylheptyl group, and decyl group. Examples of the alkylene group having 2 to 4 carbon atoms represented by A include methylene group, ethylene group, trimethylene group, and various butylene groups. Among these, an ethylene group is preferred. n is preferably an integer of 1 to 5, more preferably an integer of 2 to 4.

[0024] x1 is an integer of 1 to 10, preferably an integer of 2 to 5, more preferably 3 or 4. x2 is an integer of 1 to 10, preferably an integer of 3 to 7, more preferably 5 or 6.

[0025] Component (B) may be used alone or in combination of two or more kinds of component (B1), and may also be used alone or in combination of two or more kinds of component (B2). Furthermore, one or more kinds of component (B1) and one or more kinds of component (B2) may be used in combination.

[0026] Component (B) can be produced, for example, by reacting an alkenyl succinic anhydride obtained by reacting a polyolefin with maleic anhydride with a polyamine to prepare an alkenyl succinimide having active amine hydrogen (a compound in which R in the above general formula (b-1) or the above general formula (b-2) is a hydrogen atom), and substituting at least a part of the active amine hydrogen with a group represented by the above R c c Examples of the polyolefin include polymers obtained by polymerizing one or more selected from α-olefins having 2 to 8 carbon atoms, and a copolymer of isobutene and 1-butene is preferred.​​ Examples of the polyamine include single diamines such as ethylenediamine, propylenediamine, butylenediamine, pentylenediamine; polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine, dibutylenetriamine, tributylenetetramine, pentapentylenehexamine; piperazine derivatives such as aminoethylpiperazine; and the like. The substitution reaction of the active amine hydrogen may be carried out by a known method. For example, a method of reacting an alkenyl succinimide compound having the active amine hydrogen with an alkyl halide that provides R in the general formula (b-1) and the general formula (b-2) c is mentioned.

[0027] In the lubricating oil composition of the present embodiment, the content of component (B) in terms of nitrogen atom is not particularly limited. However, from the viewpoint of making the anti-wear property and clutch friction characteristics better, based on the total amount of the lubricating oil composition, it is preferably 100 to 1000 mass ppm, more preferably 120 to 800 mass ppm, still more preferably 130 to 600 mass ppm, and even more preferably 140 to 400 mass ppm.

[0028] In the lubricating oil composition of the present embodiment, the content of component (B) is preferably adjusted so that the content in terms of nitrogen atom is within the above range. Specifically, from the viewpoint of making the anti-wear property and clutch friction characteristics better, based on the total amount (100% by mass) of the lubricating oil composition, it is preferably 1.0 to 10.0% by mass, more preferably 1.2 to 8.0% by mass, still more preferably 1.3 to 6.0% by mass, and even more preferably 1.4 to 4.0% by mass.

[0029] The lubricating oil composition of the present embodiment may contain other ashless dispersants other than component (B) as long as the effects of the present invention are not impaired, or may not contain other ashless dispersants other than component (B). Examples of other ashless dispersants include, for example, the following component (B') and its boron compounds, benzylamines, boron-containing benzylamines, succinic esters, fatty acids or monovalent or divalent carboxylic acid amides represented by succinic acid, and the like. In the lubricating oil composition of the present embodiment, from the viewpoint of making the anti-wear property and clutch friction characteristics better, the content of component (B) in the ashless dispersant is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass with respect to the total amount (100% by mass) of the ashless dispersant contained in the lubricating oil composition. Further, in the lubricating oil composition of the present embodiment, the total content of the succinimide represented by the following general formula (i) and the succinimide bisimide represented by the following general formula (ii) (hereinafter, these are also referred to as "component (B')") is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, still more preferably less than 1 part by mass with respect to 100 parts by mass of the total amount of component (B) from the viewpoint of making the anti-wear property better. Further, the lubricating oil composition of the present embodiment may not contain component (B').

Chemical formula

[0030] <Metal detergent (C)> The metal detergent (C) is at least one selected from a metal sulfonate (C1) having a branched alkyl group and a metal phenate (C2) having a branched alkyl group. The lubricating oil composition of the present embodiment can increase the clutch friction coefficient by containing component (C). This is presumably because component (C) has a branched-chain alkyl group, and thus the resistance to shear force is greater than that of those having a straight-chain alkyl group. At the same time, although the detailed mechanism is unknown, component (C) exhibits a synergistic effect of significantly improving the wear resistance while imparting excellent clutch friction characteristics when used in combination with component (B) described above.

[0031] As the metal atom contained in the metal-based detergent (C), from the viewpoint of improving detergency, a metal atom selected from an alkali metal atom and an alkaline earth metal atom is preferable, a sodium atom, a calcium atom, a magnesium atom, and a barium atom are more preferable, a calcium atom and a magnesium atom are still more preferable, and a calcium atom is even more preferable. That is, the metal-based detergent (C) is preferably at least one selected from calcium sulfonate having a branched-chain alkyl group and calcium phenate having a branched-chain alkyl group (hereinafter, these are also referred to as "calcium-based detergents"). The content of the calcium-based detergent in the metal-based detergent (C) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass with respect to the total amount (100% by mass) of the metal-based detergent (C) contained in the lubricating oil composition.

[0032] The number of carbon atoms of the branched-chain alkyl group of component (C1) and component (C2) is preferably 3 to 26, more preferably 7 to 24, and still more preferably 10 to 20. Also, the number of carbon atoms of the branched chain of the branched-chain alkyl group is preferably 1 to 8, more preferably 2 to 6, and still more preferably 2 to 5.

[0033] As the metal sulfonate (C1) having a branched-chain alkyl group, a compound represented by the following general formula (c-1) is preferable, and as the metal phenate (C2) having a branched-chain alkyl group, a compound represented by the following general formula (c-2) is preferable.

[0034] [Chemical formula]

[0035] In the above general formulas (c-1) and (c-2), M is a metal atom selected from an alkali metal atom and an alkaline earth metal atom, preferably a sodium atom, a calcium atom, a magnesium atom, a barium atom, more preferably a calcium atom, a magnesium atom, and even more preferably a calcium atom. p is the valence of M and is 1 or 2. q is an integer of 0 or more, preferably an integer of 0 to 3. R 1 ~R 3 each independently represents a branched-chain alkyl group. The number of carbon atoms of the above branched-chain alkyl group is preferably 3 to 26, more preferably 7 to 24, and even more preferably 10 to 20. The number of carbon atoms of the branched chain of the branched-chain alkyl group is preferably 1 to 8, more preferably 2 to 6, and even more preferably 2 to 5.

[0036] Component (C) may be used alone or in combination of two or more of component (C1), or may be used alone or in combination of two or more of component (C2). Furthermore, one or more of component (C1) and one or more of component (C2) may be used in combination.

[0037] The metal detergent (C) may be any of a neutral salt, a basic salt, an overbased salt, or a mixture thereof. When the metal detergent (C) is a neutral salt, the base number of the neutral salt is preferably 0 to 30 mgKOH / g, more preferably 0 to 25 mgKOH / g, and even more preferably 0 to 20 mgKOH / g. When the metal-based detergent (C) is a basic salt or an overbased salt, the base number of the basic salt or overbased salt is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, still more preferably 160 to 500 mgKOH / g, and even more preferably 200 to 450 mgKOH / g. In this specification, the "base number" means the base number measured by the perchloric acid method in accordance with 7. of JIS K2501 "Petroleum products and lubricating oils - Neutralization value test method".

[0038] In the lubricating oil composition of this embodiment, the content in terms of metal atoms of component (C) is not particularly limited. However, from the viewpoint of making the anti-wear property and clutch friction characteristics better, based on the total amount of the lubricating oil composition, it is preferably 100 to 5000 mass ppm, more preferably 200 to 4000 mass ppm, still more preferably 300 to 3000 mass ppm, and even more preferably 500 to 2500 mass ppm.

[0039] In the lubricating oil composition of this embodiment, the content of component (C) is preferably adjusted so that the content in terms of metal atoms falls within the above range. Specifically, from the viewpoint of making the anti-wear property and clutch friction characteristics better, based on the total amount (100% by mass) of the lubricating oil composition, it is preferably 0.1 to 6.0% by mass, more preferably 0.3 to 4.0% by mass, still more preferably 0.4 to 3.5% by mass, and even more preferably 0.5 to 2.5% by mass.

[0040] In the lubricating oil composition of this embodiment, the content ratio [N / M] of the nitrogen atom (N) derived from component (B) to the metal atom (M) derived from component (C) is preferably 0.05 to 2.00, more preferably 0.06 to 0.50, and still more preferably 0.07 to 0.40 in terms of mass ratio, from the viewpoint of making the anti-wear property and clutch friction characteristics better.

[0041] The lubricating oil composition of this embodiment may contain other metal-based detergents other than component (C) as long as the effects of the present invention are not impaired, or may not contain other metal-based detergents other than component (C). Examples of other metal detergents include metal salicylates, metal detergents having a linear alkyl group, and the like. In the lubricating oil composition of the present embodiment, from the viewpoint of making the clutch friction characteristics better, the content of the metal salicylate is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, still more preferably less than 1 part by mass, based on 100 parts by mass of the total amount of component (C). Further, the lubricating oil composition of the present embodiment may not contain a metal salicylate. In the lubricating oil composition of the present embodiment, from the viewpoint of making the antiwear property and the clutch friction characteristics better, the content of the metal detergent having a linear alkyl group is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, still more preferably less than 1 part by mass, based on 100 parts by mass of the total amount of component (C). Further, the lubricating oil composition of the present embodiment may not contain a metal detergent having a linear alkyl group.

[0042] <Zinc dithiophosphate (D)> The lubricating oil composition of the present embodiment further contains zinc dithiophosphate (D). Zinc dithiophosphate (D) has the effect of improving the antiwear property. However, in the lubricating oil composition of the present embodiment, by using component (B) and component (C) in combination, even when the content of component (D) is reduced and the phosphorus content derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition, excellent antiwear property and clutch friction characteristics can be obtained. Zinc dithiophosphate (D) may be used alone or in combination of two or more.

[0043] Examples of zinc dithiophosphate (D) include compounds represented by the following general formula (d-1).

[0044] [Chemical formula] (In the formula, R 11 ~R 14Each independently represents a hydrocarbon group having 1 to 24 carbon atoms.)

[0045] R 11 ~R 14 Examples of the hydrocarbon group represented by ~R include linear or branched alkyl groups having 1 to 24 carbon atoms, linear or branched alkenyl groups having 3 to 24 carbon atoms, cycloalkyl groups or linear or branched alkylcycloalkyl groups having 5 to 13 carbon atoms, aryl groups or linear or branched alkylaryl groups having 6 to 18 carbon atoms, and arylalkyl groups having 7 to 19 carbon atoms. Among these, linear or branched alkyl groups having 1 to 24 carbon atoms are preferred, and branched alkyl groups having 1 to 24 carbon atoms are more preferred. The number of carbon atoms of the branched alkyl group is preferably 2 to 12, more preferably 3 to 6. Examples of the branched alkyl group having 1 to 24 carbon atoms include iso-propyl group, iso-butyl group, sec-butyl group, tert-butyl group, iso-pentyl group, tert-pentyl group, iso-hexyl group, 2-ethylhexyl group, iso-nonyl group, iso-decyl group, iso-tridecyl group, iso-stearyl group, iso-icosyl group, etc. Among these, sec-butyl group is preferred. As zinc dithiophosphate (D), zinc dialkyldithiophosphate is specifically preferred, and among them, secondary zinc dialkyldithiophosphate is more preferred.

[0046] In the lubricating oil composition of the present embodiment, the content of phosphorus atoms derived from component (D) is not particularly limited as long as it is less than 800 mass ppm based on the total amount of the lubricating oil composition. However, from the viewpoint of suppressing poisoning of the exhaust gas catalyst, it is preferably less than 700 mass ppm, more preferably less than 650 mass ppm, still more preferably less than 620 mass ppm. Also, from the viewpoint of improving anti-wear properties, it is preferably 100 mass ppm or more, more preferably 400 mass ppm or more.

[0047] In the lubricating oil composition of the present embodiment, the content of zinc dithiophosphate (D) is preferably adjusted so that the content in terms of phosphorus atoms falls within the above range. Specifically, from the viewpoint of suppressing poisoning of the exhaust gas catalyst, based on the total amount (100% by mass) of the lubricating oil composition, it is preferably less than 1.0% by mass, more preferably less than 0.9% by mass, still more preferably less than 0.8% by mass. Also, from the viewpoint of improving anti-wear properties, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more.

[0048] <Other additives for lubricating oil> The lubricating oil composition of the present embodiment may contain other additives for lubricating oil other than the above components as long as the effects of the present invention are not impaired. Examples of other additives for lubricating oil include antioxidants, viscosity index improvers, pour point depressants, anti-wear agents, extreme pressure agents, metal-based friction modifiers, rust preventives, metal deactivators, demulsifiers, defoamers, and the like. These additives for lubricating oil may be used alone or in combination of two or more.

[0049] Examples of antioxidants include amine-based antioxidants, phenol-based antioxidants, molybdenum-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like. Among these, one or more selected from amine-based antioxidants and phenol-based antioxidants are preferred.

[0050] Examples of viscosity index improvers include polymers such as non-dispersed polymethacrylates, dispersed polymethacrylates, olefin copolymers (e.g., ethylene-propylene copolymers, etc.), dispersed olefin copolymers, styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers, etc.).

[0051] Examples of pour point depressants include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, polyalkylstyrenes, and the like.

[0052] Examples of the antiwear agent or extreme pressure agent include sulfur-containing compounds such as molybdenum dithiocarbamate, molybdenum dithiophosphate, disulfides, sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiocarbonates, thiocarbamates, polysulfides, etc.; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and amine salts or metal salts thereof; sulfur- and phosphorus-containing compounds such as thiophosphites, thiophosphates, thiophosphonates, and amine salts or metal salts thereof.

[0053] Examples of the metal-based friction modifier include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid. However, from the viewpoint of obtaining excellent clutch friction characteristics, the content of the molybdenum-based friction modifier in the lubricating oil composition of the present embodiment is preferably as small as possible. In the lubricating oil composition of the present embodiment, the content of molybdenum atoms is preferably less than 50 mass ppm, more preferably less than 30 mass ppm, and still more preferably less than 10 mass ppm based on the total amount of the lubricating oil composition. Further, the lubricating oil composition of the present embodiment may not contain molybdenum atoms.

[0054] Examples of the rust inhibitor include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers, etc.

[0055] Examples of the metal deactivator include benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, pyrimidine-based compounds, etc.

[0056] Examples of the anti-emulsifier include anionic surfactants such as sulfuric acid ester salts of castor oil and petroleum sulfonates; cationic surfactants such as quaternary ammonium salts and imidazolines; polyoxyalkylene polyglycols and esters of dicarboxylic acids thereof; alkylene oxide adducts of alkylphenol-formaldehyde polycondensates; and the like.

[0057] Examples of the defoaming agent include silicone oil, fluorosilicone oil, fluoroalkyl ether, and the like.

[0058] The contents of the other lubricant additives described above can be appropriately adjusted within a range that does not impair the effects of the present invention. For each of them, based on the total amount (100% by mass) of the lubricant composition, it is usually 0.001 to 15% by mass, preferably 0.005 to 10% by mass, more preferably 0.01 to 7% by mass, and still more preferably 0.03 to 5% by mass. In this specification, additives such as viscosity index improvers and defoaming agents may be blended with other components in the form of a solution diluted and dissolved in a part of the above-described base oil (A) in consideration of handleability, solubility in the base oil (A), and the like. In such a case, in this specification, the above-described contents of additives such as defoaming agents and viscosity index improvers mean the contents in terms of the active ingredient (resin content) excluding the diluent oil.

[0059] In the lubricant composition of the present embodiment, the total content of component (A), component (B), component (C), and component (D) is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount (100% by mass) of the lubricant composition, and is usually 100% by mass or less.

[0060] [Various properties of the lubricant composition] The kinematic viscosity at 100 °C of the lubricant composition of the present embodiment is preferably 8.0 to 20.0 mm 2 / s, more preferably 9.0 to 18.0 mm 2 / s, still more preferably 10.0 to 15.0 mm 2 / s. Also, the kinematic viscosity at 40°C of the lubricating oil composition of the present embodiment is preferably 40.0 to 140.0 mm 2 / s, more preferably 60.0 to 130.0 mm 2 / s, still more preferably 80.0 to 120.0 mm 2 / s. The viscosity index of the lubricating oil composition of the present embodiment is preferably 80 or more, more preferably 85 or more, still more preferably 90 or more, and even more preferably 95 or more.

[0061] In the lubricating oil composition of the present embodiment, the wear width measured based on the methods and conditions of the examples described below is preferably 150 μm or less, more preferably 140 μm or less, still more preferably 135 μm or less, and even more preferably 130 μm or less. There is no particular limitation on the lower limit value of the wear width, but it may be 100 μm or more in consideration of the balance with other characteristics.

[0062] In the lubricating oil composition of the present embodiment, the friction coefficient measured based on the methods and conditions of the examples described below is preferably 0.147 or more, more preferably 0.148 or more, still more preferably 0.149 or more, and even more preferably 0.150 or more. There is no particular limitation on the upper limit value of the friction coefficient, but it may be 0.200 or less in consideration of the balance with other characteristics.

[0063] In the lubricating oil composition of the present embodiment, the phosphorus atom content is preferably less than 700 mass ppm, more preferably less than 650 mass ppm, still more preferably less than 620 mass ppm, from the viewpoint of reducing the load on the exhaust gas aftertreatment device, based on the total amount of the lubricating oil composition.

[0064] [Use of the lubricating oil composition] The lubricating oil composition of the present embodiment can exhibit excellent wear resistance in an internal combustion engine and a high friction coefficient in a wet clutch even when the phosphorus atom content derived from the anti-wear agent is reduced. The lubricating oil composition of the present embodiment is used in an internal combustion engine, and in particular, it is preferably used as an engine lubricating oil for an internal combustion engine of a two-wheeled vehicle. In addition, since the lubricating oil composition of the present embodiment has a reduced phosphorus atom content, it is also preferably used in an internal combustion engine equipped with a post-treatment device including an exhaust gas catalyst.

[0065] Further, the present embodiment can also provide the internal combustion engine shown in the following [1] and the usage method shown in the following [2]. [1] A base oil (A), An imide compound (B) which is at least one selected from the succinimide (B1) represented by the above general formula (b-1) and the succinimide (B2) represented by the above general formula (b-2), A metal-based detergent (C) which is at least one selected from a metal sulfonate (C1) having a branched-chain alkyl group and a metal phenate (C2) having a branched-chain alkyl group, Zinc dithiophosphate (D), A lubricating oil composition containing the same, An internal combustion engine using a lubricating oil composition in which the content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition. [2] A base oil (A), An imide compound (B) which is at least one selected from the succinimide (B1) represented by the above general formula (b-1) and the succinimide (B2) represented by the above general formula (b-2), A metal-based detergent (C) which is at least one selected from a metal sulfonate (C1) having a branched-chain alkyl group and a metal phenate (C2) having a branched-chain alkyl group, Zinc dithiophosphate (D), A lubricating oil composition containing the same, A usage method of the lubricating oil composition, wherein a lubricating oil composition in which the content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition is used in an internal combustion engine.

[0066] Regarding the lubricating oil compositions used in the above [1] and [2], the preferred embodiments of each component, the preferred properties of the lubricating oil compositions, etc. are as described above. Further, the internal combustion engines described in the above [1] and [2] are more preferably internal combustion engines of motorcycles.

[0067] [Method for producing lubricating oil composition] This embodiment is a method for producing a lubricating oil composition by mixing a base oil (A) with an imide compound (B) which is at least one selected from the succinimide (B1) represented by the above general formula (b-1) and the succinimide (B2) represented by the above general formula (b-2), a metal detergent (C) which is at least one selected from a metal sulfonate (C1) having a branched alkyl group and a metal phenate (C2) having a branched alkyl group, zinc dithiophosphate (D), and, also provides a method for producing a lubricating oil composition for use in an internal combustion engine, wherein the content of phosphorus atoms derived from component (D) is less than 800 mass ppm based on the total amount of the lubricating oil composition. The method for mixing the above components is not particularly limited. For example, a method having a step of blending component (B), component (C), and component (D) into base oil (A) can be mentioned. Also, the above other lubricating oil additives may be blended simultaneously with components (A) to (D). Further, each component may be blended after being made into a solution (dispersion) form by adding a diluent oil or the like. After blending each component, it is preferable to stir and uniformly disperse by a known method.

Examples

[0068] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples. The various properties of each component used in the examples and comparative examples and the obtained lubricating oil compositions were measured by the following methods.

[0069] [Kinematic viscosity, viscosity index] Measured or calculated in accordance with JIS K2283:2000. <Base number (perchloric acid method)> It was measured in accordance with JIS K2501. <Contents of phosphorus atom, calcium atom and molybdenum atom> It was measured in accordance with JPI-5S-38-03. <Content of nitrogen atom> It was measured in accordance with JIS K 2609.

[0070] Examples 1 to 7, Comparative Examples 1 to 4 The following base oils and various additives were added in the blending amounts shown in Table 1 and thoroughly mixed to prepare lubricating oil compositions, respectively. Details of the base oils and various additives used in the examples and comparative examples are as shown below.

[0071] (Component (A)) · "Base oil (a)": A 500N mineral oil that has been hydrorefined and classified into Group 2 in the API base oil category, kinematic viscosity at 40 °C = 91.4 mm 2 / s, kinematic viscosity at 100 °C = 10.5 mm 2 / s, viscosity index = 97.

[0072] (Component (B)) · Component (B2) "Modified alkenyl succinimide": The succinimide represented by the above general formula (b-2) (where R A1 and R A2 are polybutenyl groups with a mass average molecular weight (Mw) of 2300, R B1 and R B2 are ethylene groups, x2 is 5, and R C is a group represented by -CH 2 CH 2 OCH 2 CH 2 OH.). Content of nitrogen atom = 1.0 mass%.

[0073] (Component (B')) · Comparative component "Unmodified alkenyl succinimide": The succinimide represented by the above general formula (ii) (where R A1 and RA2 is a polybutenyl group with a mass average molecular weight (Mw) of 950, and R B1 and R B2 are ethylene groups, and x2 is 3.). Content of nitrogen atom = 1.9 mass%. · Comparative component "unmodified alkenyl succinimide": The succinimide represented by the above general formula (i) (R in formula (i) A is a polybutenyl group with a mass average molecular weight (Mw) of 950, and R B is an ethylene group, and x1 is 3.). Content of nitrogen atom = 1.8 mass%.

[0074] (Component (C)) · Component (C1) "branched Ca sulfonate": Calcium sulfonate having a branched-chain alkyl group (alkyl group mainly having 16 carbon atoms with a butyl group branch in the molecular structure), base number 300 mgKOH / g, calcium atom content 11.6 mass%. · Component (C2) "branched Ca phenate": Calcium phenate having a branched-chain alkyl group (alkyl group mainly having 12 carbon atoms with a branch of an ethyl group and / or a propyl group in the molecular structure), base number 250 mgKOH / g, calcium atom content = 9.3 mass%.

[0075] (Component (C')) · Comparative component "linear Ca sulfonate": Calcium sulfonate having a linear alkyl group (linear alkyl group mainly having 16 carbon atoms), base number 300 mgKOH / g, calcium atom content = 11.9 mass%.

[0076] (Component (D)) · ZnDTP: Zinc dialkyldithiophosphate having a sec-butyl group as an alkyl group (R in general formula (d-1) 11 ~R 14 is an alkyl compound having a sec-butyl group), phosphorus atom content = 7.1 mass%.

[0077] (Other lubricating additives) · Amine-based antioxidant: Dinonyldiphenylamine

[0078] In addition, the following tests were conducted on the prepared lubricating oil composition. The results are shown in Table 1.

[0079] [Evaluation of anti-wear property] Using an SRV tester (manufactured by Optimol), a friction test was carried out under the following conditions using the prepared lubricating oil composition, and the wear width (mm) at the center of the cylinder after the test time elapsed was measured. The smaller the value of the wear width, the better the anti-wear property. When the wear width was 150 μm or less, it was judged that the anti-wear property was good. · Material of cylinder: SUJ-2 · Material of disk: SUJ-2 · Frequency: 50 Hz · Amplitude: 1.5 mm · Load: 400 N · Oil temperature: 80 °C · Test time: 60 minutes

[0080] [Evaluation of friction coefficient] Using an MTM (Mini Traction Machine) tester, the friction coefficient was measured under the following conditions. When the value of the friction coefficient was 0.147 or more, which was the friction coefficient of JAFRE A16 (standard oil) under the same conditions, it was judged to be good. · Test piece: Standard test piece AISI 52100 (3 / 4 inch ball) · Disk: A disk with a clutch material (R4 material) attached to the surface of a steel disk · Running-in time: 10 minutes · Load: 3 N · Oil temperature: 100 °C · Speed: 100 mm / s · Slip ratio (SRR): 200%

[0081]

Table 1

[0082] Even when the content of phosphorus atoms derived from the antiwear agent ((D) component) in the lubricating oil compositions prepared in Examples 1 to 7 was reduced to 600 mass ppm, the wear width was small, the antiwear property was excellent, and they had a high coefficient of friction. On the other hand, the lubricating oil compositions of Comparative Examples 1 and 2 that did not use component (B) had a large wear width and were inferior in antiwear property. Also, the lubricating oil compositions of Comparative Examples 3 and 4 that did not use component (C) had a large wear width and were inferior in antiwear property, and the coefficient of friction was also low. Further, when comparing Comparative Examples 3 and 4 that used component (C’) with Comparative Example 4 that used component (B’), in Comparative Example 3 that used component (B), the wear width was reduced by 12 μm compared to Comparative Example 4 that used component (B’). On the other hand, when comparing Comparative Example 1 and Example 1 that used component (C), in Example 1 that used component (B), the wear width was reduced by 30 μm compared to Comparative Example 1 that used component (B’). Thus, it can be seen that when the lubricating oil composition of the present embodiment uses component (B) and component (C) in combination, even when the content of phosphorus atoms derived from the antiwear agent is reduced, it exhibits a synergistic effect of significantly improving the antiwear property while expressing a high coefficient of friction.

Claims

1. Base oil (A), An imide compound (B) which is one or more selected from succinimide bisimides (B2) represented by the following general formula (b-2), A metal detergent (C) which is a metal sulfonate (C1) having a branched alkyl group represented by the general formula (c-1), Zinc dithiophosphate (D), A lubricating oil composition containing the same, The content of the imide compound (B) is 1.0 to 10.0% by mass based on the total amount (100% by mass) of the lubricating oil composition, The content of the metal sulfonate (C1) is 0.1 to 6.0% by mass based on the total amount (100% by mass) of the lubricating oil composition, The content of the phosphorus atom derived from component (D) is less than 800 ppm by mass based on the total amount of the lubricating oil composition, The total content of the succinimide monoimide represented by the general formula (i) and the succinimide bisimide represented by the general formula (ii) is less than 10 parts by mass with respect to 100 parts by mass of the total amount of the imide compound (B). A lubricating oil composition used in an internal combustion engine. 【Chemical 1】 [In the general formula (b-2), R Ａ１ and R Ａ２ are each independently a polybutenyl group having a mass average molecular weight (Mw) of 1,800 to 2,400 or a polyisobutenyl group having an Mw of 1,800 to 2,400. R Ｂ１ and R Ｂ２ each independently represents a methylene group, an ethylene group, a trimethylene group, a linear butylene group, a branched butylene group, a linear pentylene group or a branched pentylene group. R Ｃ is a group represented by -(AO) ｎ -H (wherein A is a methylene group, an ethylene group, a trimethylene group, a linear butylene group or a branched butylene group, and n represents an integer of 2 to 4). x2 is 5 or 6.] 【Chemical Formula 2】 [In the above general formula (c-1), M is a metal atom selected from an alkali metal atom and an alkaline earth metal atom. p is 1 or 2. R １ is a branched alkyl group. 【Chemical 3】 In the above general formulas (i) and (ii), R Ａ , R Ａ１ and R Ａ２ are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 4000. R Ｂ , R Ｂ１ and R Ｂ２ is each independently an alkylene group having 2 to 5 carbon atoms. x1 is an integer from 1 to 10, and x2 is an integer from 1 to 10.]

2. The lubricating oil composition according to claim 1, wherein the content of component (B) in terms of nitrogen atom is 100 to 1000 ppm by mass based on the total amount of the lubricating oil composition.

3. The lubricating oil composition according to claim 1 or 2, wherein the content of component (C) in terms of metal atom is 100 to 5000 ppm by mass based on the total amount of the lubricating oil composition.

4. The lubricating oil composition according to any one of claims 1 to 3, wherein the content ratio [N / M] of the nitrogen atom (N) derived from component (B) to the metal atom (M) derived from component (C) is 0.05 to 2.00 in terms of mass ratio.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein component (C) is a calcium sulfonate having a branched alkyl group.

6. The lubricating oil composition according to any one of claims 1 to 5, wherein the content of the metal detergent having a linear alkyl group is less than 10 parts by mass with respect to 100 parts by mass of the total amount of component (C).

7. The lubricating oil composition according to any one of claims 1 to 6, wherein the content of molybdenum atoms is less than 50 ppm by mass based on the total amount of the lubricating oil composition.

8. The lubricating oil composition according to any one of claims 1 to 7, which is used for an internal combustion engine of a two-wheeled vehicle.

9. Base oil (A), An imide compound (B) which is one or more selected from succinimide bisimides (B2) represented by the following general formula (b-2), A metal detergent (C) which is a metal sulfonate (C1) having a branched alkyl group represented by the general formula (c-1), Zinc dithiophosphate (D), A method for producing a lubricating oil composition by mixing, The content of the imide compound (B) is 1.0 to 10.0% by mass based on the total amount (100% by mass) of the lubricating oil composition, The content of the metal sulfonate (C1) is 0.1 to 6.0% by mass based on the total amount (100% by mass) of the lubricating oil composition, The content of the phosphorus atom derived from the component (D) is less than 800 ppm by mass based on the total amount of the lubricating oil composition, A method for producing a lubricating oil composition for an internal combustion engine, wherein the total content of the succinimide monoimide represented by the general formula (i) and the succinimide bisimide represented by the general formula (ii) is less than 10 parts by mass with respect to 100 parts by mass of the total amount of the imide compound (B). 【Chemical Formula 4】 (In the above general formula (b-2), R Ａ１ and R Ａ２ are each independently a polybutenyl group having a mass average molecular weight (Mw) of 1800 to 2400 or a polyisobutenyl group having an Mw of 1800 to 2400.) R Ｂ１ and R Ｂ２ each independently represents a methylene group, an ethylene group, a trimethylene group, a linear butylene group, a branched butylene group, a linear pentylene group or a branched pentylene group. R Ｃ is a group represented by -(AO) ｎ -H (wherein A is a methylene group, an ethylene group, a trimethylene group, a linear butylene group or a branched butylene group, and n represents an integer of 2 to 4). x2 is 5 or 6. ] 【Chemical Formula 5】 〔In the above general formula (c-1), M is a metal atom selected from an alkali metal atom and an alkaline earth metal atom. p is 1 or 2. R １ is a branched alkyl group. ​ In the above general formulas (i) and (ii), R Ａ , R Ａ１ and R Ａ２ are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 4000. R Ｂ , R Ｂ１ and R Ｂ２ are each independently an alkylene group having 2 to 5 carbon atoms. x1 is an integer of 1 to 10, and x2 is an integer of 1 to 10. ]

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