Lubricant oil composition

Abstract

To provide a lubricant oil composition evaporating a smaller amount of oil at a lower temperature, and capable of improving fuel efficiency.SOLUTION: The lubricating oil composition includes base oil (A) in which a fraction including a hydrocarbon group having 14 or more and less than 16 carbon atoms is present within a range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and a fraction containing a hydrocarbon group having 16 or more and less than 18 carbon atoms is present within a range of 0.35 to 1.85 mass% based on the total amount of the base oil (A).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a lubricating oil composition. [Background technology]

[0002] The NOACK test at 250°C specified in ASTM D5800 is widely used as an index of oil volatility, but as engines become more sophisticated, it is sometimes difficult to obtain a correlation between the NOACK value and the amount of oil evaporation (consumption) under actual operating conditions.Under such circumstances, it has been reported that the value of oil volatility at lower temperatures is correlated with the actual amount of oil consumption (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Proceedings of the Society of Automotive Engineers of Japan, Vol.52, No.6, November 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] Under these circumstances, there has been a demand for the development of a lubricating oil composition that reduces the amount of oil evaporation at low temperatures and that can improve fuel economy. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have found that the above problems can be solved by using a predetermined amount of a base oil of a specific fraction, and have thus completed the present invention. That is, the present invention provides the following aspects. [1] A lubricating oil composition comprising a base oil (A) in which a fraction containing a hydrocarbon group having a carbon number of 14 or more and less than 16 is in the range of 0.10 to 0.60 mass % based on the total amount of the base oil (A), and a fraction containing a hydrocarbon group having a carbon number of 16 or more and less than 18 is in the range of 0.35 to 1.85 mass % based on the total amount of the base oil (A). Effect of the Invention

[0006] A preferred embodiment of the present invention provides a lubricating oil composition that reduces the amount of oil evaporation at temperatures below 250° C. In addition, a preferred embodiment of the present invention provides a lubricating oil composition that has a small kinetic viscosity at 40° C. and can improve fuel economy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The upper and lower limit values ​​of the numerical ranges described in this specification can be arbitrarily combined. For example, when the numerical range is described as "preferably 30 to 100, more preferably 40 to 80", the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described in this specification. In addition, when the numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less", the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described in this specification. In addition, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more (60 or more) and 100 or less (100 or less)." Furthermore, in defining the upper and lower limits described in this specification, a numerical range from the lower limit to the upper limit can be defined by appropriately selecting from the respective options and combining them in any desired manner. In addition, various features described as preferred embodiments in this specification may be combined in multiple ways.

[0008] [Constitution of lubricating oil composition] The lubricating oil composition of one embodiment of the present invention comprises a base oil (A) (hereinafter also referred to as "component (A)") in which a fraction containing hydrocarbon groups having a carbon number of 14 or more and less than 16 is in the range of 0.10 to 0.60 mass % based on the total amount of base oil (A), and a fraction containing hydrocarbon groups having a carbon number of 16 or more and less than 18 is in the range of 0.35 to 1.85 mass % based on the total amount of base oil (A). According to this configuration, since the NOACK value at 150°C can be made less than the specified value, it is possible to obtain a lubricating oil composition that consumes less oil even under practical use conditions. Also, according to this configuration, it is possible to obtain a lubricating oil composition that has a small kinetic viscosity at 40°C and is excellent in fuel saving properties. In this specification, the NOACK value at 150° C. means a value measured at 150° C. for 12 hours in accordance with ASTM D5800 (hereinafter, sometimes referred to as NOACK 150° C.). Each component contained in the lubricating oil composition according to one embodiment of the present invention will now be described in detail.

[0009] <Component (A): Base oil> The lubricating oil composition of the present invention uses as base oil (A) a fraction containing a hydrocarbon group having a carbon number of 14 or more and less than 16 in the range of 0.10 to 0.60 mass% based on the total amount of base oil (A), and a fraction containing a hydrocarbon group having a carbon number of 16 or more and less than 18 in the range of 0.35 to 1.85 mass% based on the total amount of base oil (A). By setting each fraction of base oil (A) in the above range, the NOACK 150°C value can be adjusted to 5 mass% or less, and oil consumption under the actual use environment of the engine can be improved. In addition, by setting each fraction of base oil (A) in the above range, the kinematic viscosity at 40°C can be adjusted to 25 mm 2 A lubricating oil composition having a fuel economy of less than 1 / s can be obtained. The fraction containing hydrocarbon groups having a carbon number of 14 or more and less than 16 is preferably 0.10 mass% or more, 0.15 mass% or more, and 0.60 mass% or less, from the viewpoint of satisfying the NOACK 150°C value and improving fuel economy. The fraction containing hydrocarbon groups having a carbon number of 16 or more and less than 18 is preferably 0.35 mass% or more, 0.40 mass% or more, or 0.50 mass% or more, while being 1.85 mass% or less, 1.80 mass% or less, 1.70 mass% or less, or 1.60 mass% or less, from the viewpoint of satisfying the NOACK 150°C value and improving fuel economy. The base oil (A) as described above can be used in accordance with the range of each fraction containing a hydrocarbon group having the above carbon number, based on the measurement results of each fraction measured by the method described in the Examples below. The base oil (A) of the present invention can be prepared, for example, by combining mineral oils, synthetic oils, or mineral oils and synthetic oils as described below, and adjusting the range of each fraction containing a hydrocarbon group with the above carbon number while taking into consideration the measurement results of each fraction measured by the method described in the Examples below.

[0010] The fractions containing a hydrocarbon group having a carbon number of 14 or more and less than 16, and the fractions containing a hydrocarbon group having a carbon number of 16 or more and less than 18, contained in the lubricating oil composition of the present invention, are, for example, obtained by mixing mineral oils and / or synthetic oils so as to contain a hydrocarbon group having the above carbon numbers. Examples of mineral oils constituting the fractions include atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate base crude oil, naphthenic crude oil, etc.; distillate oils obtained by vacuum distillation of these atmospheric residual oils; refined oils obtained by subjecting the distillate oils to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining; and the like. The base oil (A) used in the lubricating oil composition of one embodiment of the present invention may be one of these mineral oils used alone, or may be a mixed oil using a combination of two or more mineral oils.

[0011] The base oil (A) used in the lubricating oil composition of one embodiment of the present invention may be a synthetic oil of one kind alone, or may be a mixed oil of a plurality of synthetic oils in combination. The base oil (A) used in the lubricating oil composition of one embodiment of the present invention may be a mixed oil of a mineral oil and a synthetic oil in combination. Examples of synthetic oils include poly-α-olefins such as α-olefins and their homopolymers, or α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ether oils such as polyphenyl ethers; ester oils such as polyol esters, dibasic acid esters, and monoesters; alkylbenzenes; alkylnaphthalenes; synthetic oils (GTL) obtained by isomerizing wax (GTL wax (Gas To Liquids WAX)) produced from natural gas by the Fischer-Tropsch process or the like, and synthetic oils (Ethylene To Liquid (ETL)) obtained by oligomerizing olefins produced using gas as a raw material. These synthetic oils may be produced from renewable resources.

[0012] Among these, the base oil used in one embodiment of the present invention preferably contains at least one selected from mineral oils classified into Group 2 and Group 3 of the API (American Petroleum Institute) base oil category, and synthetic oils.

[0013] The lubricating oil composition of one embodiment of the present invention preferably further contains one or more base oils selected from the group consisting of poly-α-olefins (A1) and ester oils (A2). By containing these base oils, it is possible to obtain a lubricating oil composition that can improve fuel economy while satisfying the NOACK 150°C value. Specific examples of the poly-α-olefin (A1) include the above-mentioned α-olefins, homopolymers thereof, and α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers). Specific examples of the ester oil (A2) include the above-mentioned polyol esters, dibasic acid esters, and monoesters. More specific examples of the ester oil (A1) include trimethylolpropane tridecanoate, 2-ethylhexyl palmitate, and bis(2-ethylhexyl) sebacate. In one embodiment of the present invention, when the base oil (A) contains one or more base oils selected from the group consisting of poly-α-olefins (A1) and ester-based oils (A2), the content of the poly-α-olefins (A1) or ester-based oils (A2), or a mixture thereof, based on the total amount (100 mass%) of the lubricating oil composition is preferably 3.0 mass% or more, more preferably 5.0 mass% or more, and even more preferably 7.0 mass% or more, from the viewpoint of satisfying the NOACK 150°C value and improving fuel economy, and is preferably 10.0 mass% or less, more preferably 9.0 mass% or less, from the viewpoint of suppressing deterioration of rubber materials.

[0014] The base oil (A) used in one embodiment of the present invention preferably has a kinematic viscosity at 100°C of 2.5 mm 2 / s or more, preferably 2.8 mm 2 / s or more, more preferably 3.0 mm 2 / s or more, and preferably 4.5 mm 2 / s or less, preferably 4.1 mm 2 / s or less, more preferably 3.8 mm 2 / s or less. The kinetic viscosity of the base oil at 100°C is 2.5 mm 2 / s or more is preferable for maintaining the oil film. On the other hand, the kinematic viscosity of the base oil at 100°C is 4.5mm 2 / s or less is preferable because it is possible to suppress power loss due to viscous resistance and obtain an effect of improving fuel efficiency. In one embodiment of the present invention, when a mixed oil is used as the base oil (A), the 100°C kinematic viscosity of the mixed oil is preferably in the above range.

[0015] In addition, the viscosity index of the base oil used in one embodiment of the present invention is preferably 80 or more, more preferably 90 or more, even more preferably 100 or more, and still more preferably 110 or more, from the viewpoint of suppressing viscosity change due to temperature change and improving fuel economy. In this specification, kinematic viscosity and viscosity index refer to values ​​measured or calculated in accordance with ASTM D455.

[0016] In the lubricating oil composition of one embodiment of the present invention, the content of base oil (A) is, based on the total amount (100 mass%) of the lubricating oil composition, 70 mass% or more, 75 mass% or more, and 99.9 mass% or less, 98 mass% or less, or 95 mass% or less.

[0017] <Component (B): Viscosity index improver> The lubricating oil composition of one embodiment of the present invention further contains a viscosity index improver (B) containing a comb polymer (B1). By containing the comb polymer (B1) as the viscosity index improver (B), the fuel economy of the lubricating oil composition can be improved. The comb polymer (B1) may be any polymer having a structure in which the main chain has many three-way branching points from which high molecular weight side chains emerge. The comb polymer (B1) used in one embodiment of the present invention is preferably a polymer having at least a structural unit (X1) derived from a macromonomer (x1). This structural unit (X1) corresponds to the above-mentioned "high molecular weight side chain". In the present invention, the above-mentioned "macromonomer (x1)" means a high molecular weight monomer having a polymerizable functional group, and is preferably a high molecular weight monomer having a polymerizable functional group at its terminal.

[0018] The comb polymer (B1) used in one embodiment of the present invention may be a homopolymer consisting of only structural units (X1) derived from one type of macromonomer (x1), or may be a copolymer containing structural units (X1) derived from two or more types of macromonomers (x1). Furthermore, the comb polymer (B1) used in one embodiment of the present invention may be a copolymer that contains, in addition to a structural unit derived from the macromonomer (x1), a structural unit (X2) derived from a monomer other than the macromonomer (x1). A specific structure of such a comb polymer is preferably a copolymer having a main chain containing a structural unit (X2) derived from a monomer (x2) and a side chain containing a structural unit (X1) derived from a macromonomer (x1).

[0019] Examples of the monomer (x2) include alkyl (meth)acrylates, nitrogen atom-containing vinyl monomers, hydroxyl group-containing vinyl monomers, phosphorus atom-containing monomers, aliphatic hydrocarbon vinyl monomers, alicyclic hydrocarbon vinyl monomers, vinyl esters, vinyl ethers, vinyl ketones, epoxy group-containing vinyl monomers, halogen element-containing vinyl monomers, esters of unsaturated polycarboxylic acids, (di)alkyl fumarates, (di)alkyl maleates, and aromatic hydrocarbon vinyl monomers.

[0020] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​calculated as standard polystyrene measured by gel permeation chromatography (GPC).

[0021] In the lubricating oil composition of one embodiment of the present invention, the content of the comb polymer (B1) is preferably 5.0 mass% or more, more preferably 5.5 mass% or more, and even more preferably 6.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of improving fuel economy. The content of the comb polymer (B1) is preferably 14.0 mass% or less, more preferably 13.0 mass% or less, and even more preferably 12.5 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.

[0022] In addition, the viscosity index improver (B) used in one embodiment of the present invention may or may not contain a viscosity index improver made of a polymer other than the above-mentioned comb polymer (B1), as long as the effects of the present invention are not impaired. Examples of such other polymers include polymers that do not fall under the category of comb polymers, such as polymethacrylate, dispersed polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers, etc.), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers, etc.).

[0023] <Component (C): Friction modifier> The lubricating oil composition of one embodiment of the present invention further contains at least one friction modifier (C) selected from the group consisting of ashless friction modifiers (C1) and molybdenum friction modifiers (C2). By containing the friction modifier (C), it is possible to obtain a lubricating oil composition having excellent friction characteristics. From the viewpoint of further improving the friction characteristics, the lubricating oil composition of one embodiment of the present invention contains both the ashless friction modifier (C1) and the molybdenum friction modifier (C2) as the friction modifier (C).

[0024] <Ashless friction modifier (C1)> The ashless friction modifier (C1) used in one embodiment of the present invention is not particularly limited, and examples thereof include ashless friction modifiers (C1) such as amine compounds, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, fatty ethers, urea compounds, and hydrazide compounds. The ashless friction modifiers (C1) may be used alone or in combination of two or more. By including the ashless friction modifier (C1), it is possible to provide a lubricating oil composition with excellent friction characteristics. Furthermore, even if the lubricating oil composition of one embodiment of the present invention contains an ester oil (A2) as the base oil (A), by incorporating an ashless friction modifier (C1) having a specific weight average molecular weight (Mw), it is possible to maintain good friction characteristics and, as a result, good fuel economy performance.

[0025] In one embodiment of the present invention, the weight average molecular weight (Mw) of the ashless friction modifier (C1) is, from the viewpoint of improving friction characteristics, preferably 100 or more and less than 50,000, 100 or more and less than 10,000, 1000 or more and less than 10,000, or 10,000 or more and less than 50,000, and more preferably 1,000 or more and less than 50,000.

[0026] In one embodiment of the present invention, the total content of the ashless friction modifiers (C1) is, from the viewpoint of providing a lubricating oil composition with excellent friction properties, preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.3 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and may be 1.0 mass% or less, 0.8 mass% or less, or 0.5 mass% or less.

[0027] <Molybdenum-based friction modifier (C2)> Examples of the molybdenum-based friction modifier (C2) used in one embodiment of the present invention include molybdenum compounds such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid. The molybdenum-based friction modifier (C2) may be used alone or in combination of two or more. Among these, the lubricating oil composition of one embodiment of the present invention preferably contains molybdenum dithiocarbamate (MoDTC) as the molybdenum-based friction modifier (C2).

[0028] <<Molybdenum dithiocarbamate (MoDTC)>> An example of the molybdenum dithiocarbamate (MoDTC) used in one embodiment of the present invention is a compound represented by the following general formula (1). [ka]

[0029] In formula (1), R 1 ~R 4are each independently a hydrocarbon group having 4 to 18 carbon atoms, and are preferably an alkyl group having 5 to 18 carbon atoms, an alkenyl group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, an alkylaryl group having 7 to 18 carbon atoms, or an arylalkyl group having 7 to 18 carbon atoms.

[0030] Examples of the alkyl group having 5 to 18 carbon atoms include a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.

[0031] Examples of the alkenyl group having 5 to 18 carbon atoms include an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, and a pentadecenyl group.

[0032] Examples of the cycloalkyl group having 5 to 18 carbon atoms include a cyclohexyl group, a dimethylcyclohexyl group, an ethylcyclohexyl group, a methylcyclohexylmethyl group, a cyclohexylethyl group, a propylcyclohexyl group, a butylcyclohexyl group, and a heptylcyclohexyl group.

[0033] Examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and a terphenyl group.

[0034] Examples of the alkylaryl group having 7 to 18 carbon atoms include a tolyl group, a dimethylphenyl group, a butylphenyl group, a nonylphenyl group, a methylbenzyl group, and a dimethylnaphthyl group.

[0035] Examples of the arylalkyl group having 7 to 18 carbon atoms include a phenylmethyl group, a phenylethyl group, and a diphenylmethyl group.

[0036] In one embodiment of the present invention, the content of molybdenum dithiocarbamate (MoDTC) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.3 mass% or more, more preferably 0.5 mass% or more, and even more preferably 0.6 mass% or more, and may be 1.0 mass% or less, 0.9 mass% or less, or 0.8 mass% or less, from the viewpoint of providing a lubricating oil composition with excellent friction properties.

[0037] <Various additives> The lubricating oil composition according to one embodiment of the present invention may contain various additives as required, provided that the effects of the present invention are not impaired. Examples of such various additives include pour point depressants, antioxidants, metallic detergents, ashless dispersants, anti-wear agents, rust inhibitors, anti-foaming agents, extreme pressure additives, and the like. These lubricating oil additives may be used alone, or two or more of them may be used in combination.

[0038] The content of each of these various additives can be appropriately adjusted within a range that does not impair the effects of the present invention, but is usually 0.001 to 15 mass%, preferably 0.005 to 10 mass%, and more preferably 0.01 to 5 mass%, for each additive independently, based on the total amount (100 mass%) of the lubricating oil composition.

[0039] Furthermore, a compound having multiple functions as the above-mentioned additives (for example, a compound having functions as an antiwear agent and an extreme pressure additive) may be used.

[0040] [Pour point depressants] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressants may be used alone or in combination of two or more kinds. Examples of pour point depressants used in one embodiment of the present invention include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrenes.

[0041] [Antioxidants] The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant. The antioxidants may be used alone or in combination of two or more kinds. Examples of the antioxidant used in one embodiment 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.

[0042] [Metal-based cleaning agents] The lubricating oil composition of one embodiment of the present invention may further contain a metallic detergent. The metallic detergent may be used alone or in combination of two or more kinds. The metal-based detergent used in one embodiment of the present invention includes metal salts such as metal sulfonates, metal salicylates, and metal phenates. The metal atom constituting the metal salt is preferably a metal atom selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium or magnesium.

[0043] [Ashless dispersant] The lubricating oil composition of one embodiment of the present invention may further contain an ashless dispersant. The ashless dispersant may be used alone or in combination of two or more kinds. The ashless dispersant used in one embodiment of the present invention is preferably an alkenyl succinimide, and may be a modified alkenyl succinimide reacted with one or more selected from a boron compound, an alcohol, an aldehyde, a ketone, an alkylphenol, a cyclic carbonate, an epoxy compound, and an organic acid.

[0044] [Anti-wear agent] The lubricating oil composition of one embodiment of the present invention may further contain an anti-wear agent. The anti-wear agents may be used alone or in combination of two or more kinds. Examples of anti-wear agents used in one embodiment of the present invention include sulfur-containing compounds such as zinc dialkyldithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and amine salts or metal salts thereof; and sulfur- and phosphorus-containing anti-wear agents such as thiophosphites, thiophosphates, thiophosphonates, and amine salts or metal salts thereof.

[0045] [Rust inhibitor] The lubricating oil composition of one embodiment of the present invention may further contain a rust inhibitor. The rust inhibitor may be used alone or in combination of two or more kinds. Examples of the rust inhibitor used in one embodiment of the present invention include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, paraffin oxide, and alkyl polyoxyethylene ethers.

[0046] [Antifoaming agent] The lubricating oil composition of one embodiment of the present invention may further contain an antifoaming agent. The antifoaming agents may be used alone or in combination of two or more kinds. Examples of the defoaming agent used in one embodiment of the present invention include alkyl silicone defoaming agents, fluoro silicone defoaming agents, and fluoroalkyl ether defoaming agents.

[0047] [Extreme pressure additives] The lubricating oil composition of one embodiment of the present invention may further contain an extreme pressure additive. The extreme pressure additives may be used alone or in combination of two or more kinds. Examples of the extreme pressure additive used in one embodiment of the present invention include sulfur-containing compounds such as zinc dialkyldithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and amine salts or metal salts thereof; and sulfur- and phosphorus-containing antiwear agents such as thiophosphites, thiophosphates, thiophosphonates, and amine salts or metal salts thereof.

[0048] [Method for producing lubricating oil composition] The method for producing the lubricating oil composition of one embodiment of the present invention is not particularly limited, and is preferably a method that includes a step of blending various other additives with the base oil (A) as necessary. The order of blending the components can be appropriately determined.

[0049] [Properties of the lubricating oil composition] The lubricating oil composition of one embodiment of the present invention preferably has a kinematic viscosity at 100°C of 5.0 mm 2 / s or more, preferably 5.5 mm 2 / s or more, more preferably 6.1 mm 2 / s or more, and preferably 12.5 mm 2 / s or less, preferably 10.0 mm 2 / s or less, more preferably 9.3 mm 2 / s or less.

[0050] The lubricating oil composition of one embodiment of the present invention preferably has a NOACK value measured in accordance with ASTM D5800 at 150°C for 12 hours of 5 mass% or less, and although there is no particular limitation to the lower limit, it is, for example, 3 mass% or more.

[0051] The coefficient of friction measured using the lubricating oil composition according to one embodiment of the present invention as a sample oil by the method described in the Examples below is preferably 0.110 or less, more preferably 0.106 or less, even more preferably less than 0.085, and even more preferably 0.084 or less. A lubricating oil composition having a coefficient of friction within the above range can be said to have excellent friction characteristics.

[0052] [Uses of the lubricating oil composition] The lubricating oil composition of the present invention has a low oil evaporation amount, as indicated by the NOACK value at 150° C., and therefore can be suitably used for lubricating internal combustion engines. Therefore, the present invention also provides the following internal combustion engine [I] and the following method for using the lubricating oil composition [II]. [I] An internal combustion engine filled with the lubricating oil composition according to one embodiment of the present invention. [II] A method for using the lubricating oil composition according to one embodiment of the present invention described above, which comprises applying the lubricating oil composition to the lubrication of an internal combustion engine.

[0053] The present invention may include the following aspects. [1] A lubricating oil composition comprising a base oil (A) in which a fraction containing a hydrocarbon group having a carbon number of 14 or more and less than 16 is in the range of 0.10 to 0.60 mass % based on the total amount of the base oil (A), and a fraction containing a hydrocarbon group having a carbon number of 16 or more and less than 18 is in the range of 0.35 to 1.85 mass % based on the total amount of the base oil (A). [2] The lubricating oil composition according to [1], comprising an ashless friction modifier (C1), wherein the weight average molecular weight (Mw) of the ashless friction modifier (C1) is 100 or more and less than 50,000. [3] The lubricating oil composition according to [1], comprising an ashless friction modifier (C1), wherein the weight average molecular weight (Mw) of the ashless friction modifier (C1) is 1,000 or more and less than 50,000. [4] The lubricating oil composition according to any one of [1] to [3], further comprising, as the base oil (A), one or more base oils selected from the group consisting of poly-α-olefins (A1) and ester-based oils (A2). [5] The lubricating oil composition according to [4], comprising an ester-based oil (A2) as the base oil (A). [6] The lubricating oil composition according to any one of [1] to [5], further comprising a viscosity index improver (B) comprising a comb polymer (B1). [7] The lubricating oil composition according to any one of [1] to [6], further comprising a molybdenum-based friction modifier (C2). EXAMPLES

[0054] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The various physical properties of the components used in the examples and comparative examples and the lubricating oil compositions obtained were measured according to the following methods.

[0055] (1) Kinematic viscosity and viscosity index Measured and calculated in accordance with ASTM D455. Kinematic viscosity at 40°C is 25mm 2 / s or less was judged to be pass. (2) Weight average molecular weight (Mw), number average molecular weight (Mn) One Tosoh Corporation column, "TSKguardcolumn SuperHZ-L" and two Tosoh Corporation columns, "TSKSuperMultipore HZ-M", were attached to a Waters Corporation "1515 Isocratic HPLC Pump" and "2414 Refractive Index (RI) Detector" in that order from the upstream side. Measurements were performed under the following conditions: measurement temperature: 40°C, mobile phase: tetrahydrofuran, flow rate: 0.35 mL / min, sample concentration: 1.0 mg / mL, and the results were calculated in terms of standard polystyrene. (3) Amount of fraction containing hydrocarbon groups having carbon atoms of 14 or more and less than 16 and carbon atoms of 16 or more and less than 18 Using the following measuring equipment and under the following measuring conditions, the peak areas of fractions containing hydrocarbon groups of each carbon number were calculated in the ranges of carbon numbers from 8 to less than 10, from 10 to less than 12, and then increasing the carbon number by 2 each time up to 36 to less than 38, and the proportions of the fractions containing hydrocarbon groups with carbon numbers of 14 to less than 16 relative to all peak areas, and the proportions of the fractions containing hydrocarbon groups with carbon numbers of 16 to less than 18 relative to all peak areas were calculated. (Measuring Equipment) Equipment: Shimadzu Corporation GC-2014 Detector type: FID Column: Packed column Filler: Silicone OV-1 1.5% Shinwasorb-S 60 / 80 (Measurement conditions) Injector temperature: 360℃ Detector temperature: 360℃ Heating conditions: Initial temperature 60℃ Heating rate: 10℃ / min Final temperature: 350℃ Final temperature hold time: 5 min Gas flow rate: N245mL / min (4) NOACK 150℃ The measurement was performed at 150°C for 12 hours in accordance with ASTM D5800. Those with a NOACK value of 5% by mass or less at 150°C were judged to pass. (5) Friction coefficient [Evaluation of friction coefficient] The friction coefficient was measured using an SRV tester (manufactured by Optimol) under the following conditions when the prepared lubricating oil composition was used. First, the temperature was raised from 30°C to 140°C in 10°C increments, and the test was carried out for 5 minutes at each temperature under the following conditions. During the final minute of the test at 30° C., the friction coefficient was measured every second, and the average friction coefficient during the final minute was calculated. Cylinder: AISI52100 Mirror disc: AISI52100 (maximum height roughness (Rz): less than 0.20 μm) Frequency: 50Hz ·Amplitude: 1.5mm Load capacity: 400N Temperature: 30~140℃, increasing by 10℃ Test time: 5 minutes at each temperature The coefficient of friction was evaluated using the improvement rate calculated by the following formula as an index, based on the coefficient of friction at 30°C measured using the sample oil of Example 1. In Tables 1 and 2, "-" means that the coefficient of friction was not measured. Formula: Improvement rate = 100 - (friction coefficient of each example at 30°C / friction coefficient of example 1 at 30°C x 100)

[0056] Examples 1 to 18, Comparative Examples 1 to 4 Lubricating oil compositions were prepared by adding and mixing the various components and other additives shown in Tables 1 and 2 in the amounts shown in Tables 1 and 2. The amounts of viscosity index improvers in Tables 1 and 2 are listed as amounts including diluent oil. Details of each component used in the preparation of the lubricating oil compositions are as follows.

[0057] <Component (A): Base oil> Base oil (A): A base oil prepared by using base oils (1) to (22) shown in Tables 1 to 2 so that the fraction having a carbon number of 14 or more and less than 16 and the fraction having a carbon number of 16 or more and less than 18 have the values ​​shown in Tables 1 to 2, respectively. 2 / s and viscosity index ranged from 111 to 164. <Component (B): Viscosity index improver> Comb polymer (B1): A comb polymer with a structure that has many three-way branching points in the main chain from which high molecular weight side chains emerge (Mw=260,000, Mw / Mn=3.1, resin content=23%) <Component (C): Friction modifier> Ashless friction modifier (C1)(1): Stearyl diethanolamine (Mw=350, N content=4.2% by weight, resin content=99%) Ashless friction modifier (C1) (2) Polymethacrylate (Mw=9800, N content=0.25% by weight, resin content=78%). Ashless friction modifier (C1)(3): Polymethacrylate (Mw=18000, N content=0.24% by weight, resin content=67%). Ashless friction modifier (C1)(4): Polymethacrylate (Mw=57000, N content=0.40% by weight, resin content=33.2%) Molybdenum-based friction modifier (C2): molybdenum dithiocarbamate (MoDTC) (R in formula (1) 1 ~R 4are each independently 8 or 13 hydrocarbon groups; X 1 ~X 4 A compound in which the molybdenum atom content is 10.0 mass%, and the sulfur atom content is 11.5 mass%. <Other additives> An additive blend comprising a mixture of detergents, dispersants, ZnDTP, antioxidants, metal deactivators, antifoam agents, and friction modifiers.

[0058] [Table 1] [Table 2]

[0059] From the results in Tables 1 and 2, the lubricating oil compositions of Examples 1 to 18, which contain a base oil (A) in which the fraction containing a hydrocarbon group having a carbon number of 14 or more and less than 16 is in the range of 0.10 to 0.60 mass% based on the total amount of base oil (A) and the fraction containing a hydrocarbon group having a carbon number of 16 or more and less than 18 is in the range of 0.35 to 1.85 mass% based on the total amount of base oil (A), had a NOACK value of 5 mass% or less at 150°C and a small amount of oil evaporation. 2 / s or less, and were excellent in fuel economy. On the other hand, the lubricating oil compositions of Comparative Examples 1 to 4 did not satisfy the pass criteria for NOACK value at 150°C or kinematic viscosity at 40°C.

Claims

1. The lubricating oil composition comprises a base oil (A) in which a fraction containing a hydrocarbon group having a carbon number of 14 or more and less than 16 is in the range of 0.10 to 0.60 mass % based on the total amount of the base oil (A), and a fraction containing a hydrocarbon group having a carbon number of 16 or more and less than 18 is in the range of 0.35 to 1.85 mass % based on the total amount of the base oil (A).

2. 2. The lubricating oil composition according to claim 1, comprising an ashless friction modifier (C1), the ashless friction modifier (C1) having a weight average molecular weight (Mw) of 100 or more and less than 50,000.

3. 2. The lubricating oil composition according to claim 1, comprising an ashless friction modifier (C1), the ashless friction modifier (C1) having a weight average molecular weight (Mw) of 1,000 or more and less than 50,000.

4. The lubricating oil composition according to any one of claims 1 to 3, further comprising, as the base oil (A), one or more base oils selected from the group consisting of poly-α-olefins (A1) and ester-based oils (A2).

5. The lubricating oil composition according to claim 4, comprising an ester-based oil (A2) as the base oil (A).

6. The lubricating oil composition of any one of claims 1 to 5, further comprising a viscosity index improver (B) comprising a comb polymer (B1).

7. The lubricating oil composition according to any one of claims 1 to 6, further comprising a molybdenum-based friction modifier (C2).

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