Lubricating oil composition

Abstract

There has been a need for development of a lubricating oil composition which is reduced in the oil evaporation amount at lower temperatures, and is capable of improving the fuel consumption saving. Disclosed is a lubricating oil composition which includes a base oil (A) in which the content of a fraction containing hydrocarbon groups having not less than 14 but less than 16 carbon atoms is within the range of 0.10% by mass to 0.60% by mass based on the total amount of the base oil (A), and the content of a fraction containing hydrocarbon groups having not less than 16 but less than 18 carbon atoms is within the range of 0.35% by mass to 1.85% by mass based on the total amount of the base oil (A).

Description

Technical Field

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

[0002] As an index of oil evaporability, a NOACK test at 250°C specified by ASTM D5800 has been widely used, but with advancement of engines, a correlation between the NOACK value and the amount of oil evaporation (amount of consumption) in an actual usage environment is not obtained occasionally. Under such circumstances, it has been reported that there is a correlation between the value of oil evaporability at lower temperatures and the amount of actual oil consumption (Non Patent Literature 1)Citation ListNon Patent LiteratureNon Patent Literature 1

[0003] Transactions of the Society of Automotive Engineers of Japan, Inc., Vol. 52, No. 6, November 2021Summary of InventionTechnical Problem

[0004] Under such circumstances, development of a lubricating oil composition which is reduced in the amount of oil evaporation at lower temperatures and is capable of improving fuel consumption saving performance has been desired.Solution to Problem

[0005] As a result of earnest studies, the present inventors have found that by using a base oil of specific fractions in a given amount, the above problem can be solved, and have completed the present invention.

[0006] That is, the present invention provides the following embodiment. [1] A lubricating oil composition comprising, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A). Advantageous Effects of Invention

[0007] One preferred embodiment of the present invention provides a lubricating oil composition which is reduced in the amount of oil evaporation at temperatures lower than 250°C. In addition, one preferred embodiment of the present invention provides a lubricating oil composition having a low kinematic viscosity at 40°C and capable of improving fuel consumption saving performance.Description of Embodiments

[0008] Regarding the numerical range described in the present specification, the upper limit and the lower limit can be combined freely. For example, with the description "preferably 30 to 100, more preferably 40 to 80" as numerical ranges, the range of "30 to 80" and the range of "40 to 100" are also included in the numerical ranges described in the present specification. Alternatively, for example, with the description "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less" as numerical ranges, the range of "30 to 80" and the range of "40 to 100" are also included in the numerical ranges described in the present specification.

[0009] In addition, for example, the description of "60 to 100" as a numerical range described in the present specification means a range of "60 or more (60 or more than 60) and 100 or less (100 or less than 100)".

[0010] The numerical range of a lower limit to an upper limit can be defined by appropriately selecting values from among respective options and optionally combining them in the definition of the upper limit and the lower limit described in the present specification.

[0011] In addition, a plurality of various requirements described in the present specification as preferred embodiments can be combined.[Constitution of lubricating oil composition]

[0012] The lubricating oil composition according to one embodiment of the present invention includes, as a base oil (A) (also referred to as a "component (A)" hereinafter), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A).

[0013] According to the present constitution, the NOACK value at 150°C can be set to less than the defined value, and therefore, a lubricating oil composition which is reduced in the amount of oil consumption even in an actual usage environment can be obtained. According to the present constitution, moreover, a lubricating oil composition having a low kinematic viscosity at 40°C and having excellent fuel consumption saving performance can be obtained.

[0014] In the present specification, the NOACK value at 150°C means a value measured at 150°C for 12 hours in accordance with ASTM D5800 (also referred to as NOACK 150°C hereinafter).

[0015] Hereinafter, details of each component contained in the lubricating oil composition according to one embodiment of the present invention will be described.<Component (A): base oil>

[0016] The lubricating oil composition of the present invention uses, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A). By setting the amounts of the individual fractions of the base oil (A) to the above ranges, the value of NOACK 150°C can be adjusted to 5 mass% or less, and the oil consumption in an actual engine usage environment can be improved. In addition, by setting the amounts of the individual fractions of the base oil (A) to the above ranges, a lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less and having excellent fuel consumption saving performance can be obtained.

[0017] The amount of the fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is preferably 0.10 mass% or more, 0.15 mass% or more, and 0.60 mass% or less, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved.

[0018] The amount of the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is preferably 0.35 mass% or more, 0.40 mass% or more, 0.50 mass% or more, while it is preferably 1.85 mass% or less, 1.80 mass% or less, 1.70 mass% or less, 1.60 mass% or less, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved.

[0019] As such a base oil (A) as above, employable is a base oil in which the amounts of the fractions are set according to the ranges of the individual fractions containing hydrocarbon groups having the above numbers of carbon atoms based on the measurement results of the individual fractions measured by the method described in Examples described later.

[0020] The base oil (A) of the present invention can be manufactured by, for example, making a combination of mineral oils described below, a combination of synthetic oils, or a combination of a mineral oil and a synthetic oil, and keeping the individual fractions containing hydrocarbon groups having the above numbers of carbon atoms within the above ranges taking into consideration the measurement results of the individual fractions measured by the method described in Examples described later.

[0021] The fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms and the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms contained in the lubricating oil composition of the present invention are those obtained by, for example, mixing a mineral oil and / or a synthetic oil so as to contain hydrocarbon groups of the above numbers of carbon atoms. Examples of the mineral oils to constitute the fractions include atmospheric residual oils obtained by subjecting crude oils, such as paraffinic crude oils, intermediate base crude oils, and naphthenic crude oils, to atmospheric distillation; distillates obtained by subjecting these atmospheric residual oils to vacuum distillation; and refined oils obtained by subjecting the distillates to one or more of refining treatments, such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0022] The base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be a base oil using one of these mineral oils singly, or may be a mixed oil using a plurality of mineral oils in combination.

[0023] The base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be one using one synthetic oil singly, or may be a mixed oil using a plurality of synthetic oils in combination. Furthermore, the base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be a mixed oil using a mineral oil and a synthetic oil in combination. Examples of the synthetic oils include α-olefins, and poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffin; polyalkylene glycol; ether-based oils, such as polyphenyl ether; ester-based oils, such as polyol esters, dibasic acid esters, and monoesters; alkylbenzene; alkylnaphthalene; synthetic oils (GTL) obtained by isomerizing waxes (GTL waxes (Gas To Liquids WAX)) produced from natural gas through Fischer-Tropsch process or the like; and synthetic oils (Ethylene To Liquid (ETL)) obtained by oligomerizing olefins produced from a gas as a raw material. These synthetic oils may be produced from recyclable resources.

[0024] Among these, the base oil for use in one embodiment of the present invention preferably contains at least one selected from mineral oils and synthetic oils classified into Group 2 and Group 3 in the API (American Petroleum Institute) base oil category.

[0025] The lubricating oil composition according to one embodiment of the present invention preferably further contains at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2). Since these base oils are contained, a lubricating oil composition satisfying the value of NOACK 150°C and capable of improving fuel consumption saving performance can be obtained.

[0026] Specific examples of the poly-α-olefins (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).

[0027] Specific examples of the ester-based oils (A2) include the above-mentioned polyol esters, dibasic acid esters, and monoesters. More specific examples of the ester-based oils (A1) include trimethylolpropane tridecanoate, 2-ethylhexyl palmitate, and bis(2-ethylhexyl) sebacate.

[0028] When one embodiment of the present invention contains, as the base oil (A), at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2), the content of the poly-α-olefin (A1) or the ester-based oil (A2) contained or a mixture of these is preferably 3.0 mass% or more, more preferably 5.0 mass% or more, much more preferably 7.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved, and it is preferably 10.0 mass% or less, more preferably 9.0 mass% or less, from the viewpoint of suppressing deterioration of a rubber material.

[0029] The kinematic viscosity at 100°C of the base oil (A) for use in one embodiment of the present invention is preferably 2.5 mm 2< / s or more, more preferably 2.8 mm 2< / s or more, much more preferably 3.0 mm 2< / s or more, and preferably 4.5 mm 2< / s or less, more preferably 4.1 mm 2< / s or less, much more preferably 2.8 mm 2< / s or less.

[0030] The kinematic viscosity at 100°C of the base oil (A) is preferably 2.5 mm 2< / s or more because of retention of oil films. On the other hand, the kinematic viscosity at 100°C of the base oil (A) is preferably 4.5 mm 2< / s or less because power loss due to the viscous resistance can be suppressed, and the fuel consumption improving effect can be achieved. When a mixed oil is used as the base oil (A) in one embodiment of the present invention, the kinematic viscosity at 100°C of the mixed oil is preferably in the above ranges.

[0031] The viscosity index of the base oil for use in one embodiment of the present invention is preferably 80 or more, more preferably 90 or more, much more preferably 100 or more, even more preferably 110 or more, from the viewpoint of suppressing the viscosity change due to the temperature change and improving the fuel consumption saving performance.

[0032] In the present specification, the kinematic viscosity and the viscosity index mean values measured or calculated in accordance with ASTM D455.

[0033] In the lubricating oil composition according to one embodiment of the present invention, the content of the base oil (A) is 70 mass% or more, 75 mass% or more, and 99.9 mass% or less, 98 mass% or less, 95 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.<Component (B): viscosity index improver>

[0034] The lubricating oil composition according to one embodiment of the present invention further contains a viscosity index improver (B) containing a comb polymer (B1). Since the comb polymer (B1) is contained as the viscosity index improver (B), the fuel consumption saving performance of the lubricating oil composition can be improved. The comb polymer (B1) suffices if it is a polymer having a structure having, on a main chain, a large number of three-way branch points from which high-molecular weight side chains extend. The comb polymer (B1) for use in one embodiment of the present invention is preferably a polymer having at least a constitutional unit (X1) derived from a macromonomer (x1). This constitutional unit (X1) corresponds to the above-mentioned "high-molecular weight side chain".

[0035] In the present invention, the "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 the terminal.

[0036] The comb polymer (B1) for use in one embodiment of the present invention may be a homopolymer composed only of a constitutional unit (X1) derived from one kind of macromonomer (x1), or may be a copolymer containing a constitutional unit (X1) derived from two or more kinds of macromonomers (x1).

[0037] Further, the comb polymer (B1) for use in one embodiment of the present invention may be a copolymer containing, together with the constitutional unit derived from the macromonomer (x1), a constitutional unit (X2) derived from a monomer other than the macromonomer (x1).

[0038] Regarding the specific structure of such a comb polymer, preferable is a copolymer having a side chain containing the constitutional unit (X1) derived from the macromonomer (x1) on a main chain containing the constitutional unit (X2) derived from a monomer (x2).

[0039] Examples of the monomers (x2) include alkyl (meth)acrylates, nitrogen atom-containing vinyl monomers, hydroxyl group-containing vinyl monomers, phosphorus atom-containing monomers, aliphatic hydrocarbon-based vinyl monomers, alicyclic hydrocarbon-based 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-based vinyl monomers.

[0040] In the present specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are values in terms of standard polystyrene, which are measured by gel permeation chromatography (GPC) .

[0041] In the lubricating oil composition according to 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, much more preferably 6.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of improving the fuel consumption saving performance. The content of the comb polymer (B1) is preferably 14.0 mass% or less, more preferably 13.0 mass% or less, much more preferably 12.5 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.

[0042] The viscosity index improver (B) for use in one embodiment of the present invention may or may not contain viscosity index improvers composed of polymers other than the above-mentioned comb polymer (B1) as long as the effects of the present invention are not impaired.

[0043] Examples of such polymers include polymers not corresponding to the comb polymers, such as polymethacrylate, dispersed polymethacrylate, olefin copolymers (for example, ethylene-propylene copolymer), dispersed olefin copolymers, and styrene copolymers (for example, styrene-diene copolymer, styrene-isoprene copolymer).<Component (C): friction modifier)

[0044] The lubricating oil composition according to one embodiment of the present invention further contains at least one friction modifier (C) selected from the group consisting of an ashless friction modifier (C1) and a molybdenum-based friction modifier (C2). Since the above friction modifier (C) is contained, a lubricating oil composition having excellent friction characteristics can be obtained. From the viewpoint of more improving the friction characteristics, the lubricating oil composition according to one embodiment of the present invention contains both the ashless friction modifier (C1) and the molybdenum-based friction modifier (C2) as the friction modifiers (C).<Ashless friction modifier (C1)>

[0045] The ashless friction modifier (C1) for use in one embodiment of the present invention is not particularly restricted, and examples thereof include ashless friction modifiers (C1), such as amine compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea-based compounds, and hydrazide-based compounds. The ashless friction modifier (C1) may be used singly or in combination of two or more.

[0046] Since the ashless friction modifier (C1) is contained, a lubricating oil composition having excellent friction characteristics can be obtained, and besides, even if the lubricating oil composition according to one embodiment of the present invention contains an ester-based oil (A2) as the base oil (A), the friction characteristics can be favorably maintained by blending the ashless friction modifier (C1) having a specific weight-average molecular weight (Mw), and as a result, the fuel consumption saving performance can be favorably maintained.

[0047] In one embodiment of the present invention, the weight-average molecular weight (Mw) of the ashless friction modifier (C1) is preferably 100 or more and less than 50,000, 100 or more and less than 10,000, 100 or more and less than 1000, 1000 or more and less than 10,000, or 10,000 or more and less than 50,000, and more preferably 1000 or more and less than 50,000, from the viewpoint of improving friction characteristics.

[0048] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition having excellent friction characteristics, the total content of the ashless friction modifier (C1) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, much more preferably 0.3 mass% or more, and may be 1.0 mass% or less, 0.8 mass% or less, 0.5 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.<Molybdenum-based friction modifier (C2)>

[0049] Examples of the molybdenum-based friction modifiers (C2) for use in one embodiment of the present invention include molybdenum-based compounds, such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid. The molybdenum-based friction modifier (C2) may be used singly or in combination of two or more.

[0050] The lubricating oil composition according to one embodiment of the present invention preferably contains, among the above compounds, molybdenum dithiocarbamate (MoDTC) as the molybdenum-based frication modifier (C2).<<Molybdenum dithiocarbamate (MoDTC) >>

[0051] The molybdenum dithiocarbamate (MoDTC) for use in one embodiment of the present invention is, for example, a compound represented by the following general formula (1).

[0052] In the formula (1), R 1< to R 4< are each independently a hydrocarbon group having 4 to 18 carbon atoms, 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.

[0053] Examples of the alkyl groups 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.

[0054] Examples of the alkenyl groups 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.

[0055] Examples of the cycloalkyl groups 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.

[0056] Examples of the aryl groups having 6 to 18 carbon atoms include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and a terphenyl group.

[0057] Examples of the alkylaryl groups 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.

[0058] Examples of the arylalkyl groups having 7 to 18 carbon atoms include a phenylmethyl group, a phenylethyl group, and a diphenylmethyl group.

[0059] In one embodiment of the present invention, the content of the molybdenum dithiocarbamate (MoDTC) is preferably 0.3 mass% or more, more preferably 0.5 mass% or more, much more preferably 0.6 mass% or more, and may be 1.0 mass% or less, 0.9 mass% or less, 0.8 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of obtaining a lubricating oil composition having excellent friction characteristics.<Various additives>

[0060] The lubricating oil composition according to one embodiment of the present invention may contain various additives when needed, as long as the effects of the present invention are not impaired.

[0061] Examples of such various additives include pour point depressants, antioxidants, metal-based detergents, ashless dispersants, antiwear agents, rust inhibitors, anti-foaming agents, and extreme-pressure additives.

[0062] These lubricating oil additives may be each used singly, or may be each used in combination of two or more.

[0063] The content of each of these various additives can be appropriately adjusted as long as the effects of the present invention are not impaired, but the contents of these additives are each independently usually 0.001 to 15 mass%, preferably 0.005 to 10 mass%, more preferably 0.01 to 5 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0064] A compound having a plurality of functions of the above additives (for example, a compound having functions of an antiwear agent and an extreme-pressure additive) may be used.[Pour point depressant]

[0065] The lubricating oil composition according to one embodiment of the present invention may further contain a pour point depressant. The pour point depressant may be used singly, or may be used in combination of two or more.

[0066] Examples of the pour point depressants for use in one embodiment of the present invention include an ethylene-vinyl acetate copolymer, condensates of chlorinated paraffins and naphthalene, condensates of chlorinated paraffins and phenol, polymethacrylates, and polyalkylstyrenes.[Antioxidant]

[0067] The lubricating oil composition according to one embodiment of the present invention may further contain an antioxidant. The antioxidant may be used singly, or may be used in combination of two or more.

[0068] Examples of the antioxidants for use 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.[Metal-based detergent]

[0069] The lubricating oil composition according to one embodiment of the present invention may further contain a metal-based detergent. The metal-based detergent may be used singly, or may be used in combination of two or more.

[0070] Examples of the metal-based detergents for use in one embodiment of the present invention include metal salts, such as metal sulfonates, metal salicylates, and metal phenates. As a metal atom to constitute the metal salts is preferably a metal atom selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and much more preferably calcium or magnesium.[Ashless dispersant]

[0071] The lubricating oil composition according to one embodiment of the present invention may further contain an ashless dispersant. The ashless dispersant may be used singly, or may be used in combination of two or more.

[0072] The ashless dispersant for use in one embodiment of the present invention is preferably an alkenyl succinimide, and may be a modified alkenyl succinimide obtained by reacting an alkenyl succinimide with one or more selected from boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, organic acids, and the like.[Antiwear agent]

[0073] The lubricating oil composition according to one embodiment of the present invention may further contain an antiwear agent. The antiwear agent may be used singly, or may be used in combination of two or more.

[0074] Examples of the antiwear agents for use in one embodiment of the present invention include sulfur-containing compounds, such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds, such as phosphite esters, phosphate esters, phosphonate esters, and amine salts or metal salts of these; and sulfur-containing and phosphorus-containing antiwear agents, such as thiophosphite esters, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts of these.[Rust inhibitor]

[0075] The lubricating oil composition according to one embodiment of the present invention may further contain a rust inhibitor. The rust inhibitor may be used singly, or may be used in combination of two or more.

[0076] Examples of the rust inhibitors for use 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, oxidized paraffin, and polyoxyethylene alkyl ethers.[Anti-foaming agent]

[0077] The lubricating oil composition according to one embodiment of the present invention may further contain an anti-foaming agent. The anti-foaming agent may be used singly, or may be used in combination of two or more.

[0078] Examples of the anti-foaming agents for use in one embodiment of the present invention include alkyl silicone-based anti-foaming agents, fluorosilicone-based anti-foaming agents, and fluoroalkyl ether-based anti-foaming agents.[Extreme-pressure additive]

[0079] The lubricating oil composition according to one embodiment of the present invention may further contain an extreme-pressure additive. The extreme-pressure additive may be used singly, or may be used in combination of two or more.

[0080] Examples of the extreme-pressure additives for use in one embodiment of the present invention include sulfur-containing compounds, such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds, such as phosphite esters, phosphate esters, phosphonate esters, and amine salts or metal salts of these; and sulfur-containing and phosphorus-containing antiwear agents, such as thiophosphite esters, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts of these.(Method for producing lubricating oil composition)

[0081] The method for producing a lubricating oil composition according to one embodiment of the present invention is not particularly restricted, but is preferably a method including a step of blending, with the base oil (A), other various additives when needed. The order of blending the components can be appropriately set.[Properties of lubricating oil composition]

[0082] The kinematic viscosity at 100°C of the lubricating oil composition according to one embodiment of the present invention is preferably 5.0 mm 2< / s or more, more preferably 5.5 mm 2< / s or more, much more preferably 6.1 mm 2< / s or more, and preferably 12.5 mm 2< / s or less, more preferably 10.0 mm 2< / s or less, much more preferably 9.3 mm 2< / s or less.

[0083] The NOACK value of the lubricating oil composition according to one embodiment of the present invention, as measured at 150°C for 12 hours in accordance with ASTM D5800, is preferably 5 mass% or less, and the lower limit is not particularly limited, but is, for example, 3 mass% or more.

[0084] The value of friction coefficient, as measured by the method described in Examples described later using the lubricating oil composition according to one embodiment of the present invention as a sample oil, is preferably 0.110 or less, more preferably 0.106 or less, much more preferably less than 0.085, even more preferably 0.084 or less. The lubricating oil composition having a value of friction coefficient in the above range can be said to be excellent in friction characteristics.[Applications of lubricating oil composition]

[0085] The lubricating oil composition of the present invention is reduced in the amount of oil evaporation that uses the NOACK vale at 150°C as an index, and hence, it can be suitably used for lubrication of internal combustion engines.

[0086] On that account, the present invention also provides an internal combustion engine set forth in [I] below and a method of using a lubricating oil composition set forth in [II] below. [I] An internal combustion engine filled with the above-mentioned lubricating oil composition according to one embodiment of the present invention. [II] A method of using a lubricating oil composition, in which the above-mentioned lubricating oil composition according to one embodiment of the present invention is applied to lubrication of an internal combustion engine.

[0087] The present invention can include the following embodiments. [1] A lubricating oil composition comprising, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms 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 ashless friction modifier (C1) has a weight-average molecular weight (Mw) of 100 or more and less than 50,000. [3] The lubricating oil composition according to [1], comprising an ashless friction modifier (C1), wherein the ashless friction modifier (C1) has 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 [1] to [3], further comprising, as the base oil (A), at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2). [5] The lubricating oil composition according to [4], comprising, as the base oil (A), an ester-based oil (A2). [6] The lubricating oil composition according to any one of [1] to [5], further comprising a viscosity index improver (B) containing 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

[0088] Next, the present invention will be described in much more detail with reference to Examples, but the present invention is in no way limited to these Examples. Various physical property values, etc. of the components used in Examples and Comparative Examples and the lubricating oil compositions obtained therein were measured in accordance with the methods described below.(1) Kinematic viscosity and viscosity index

[0089] The kinematic viscosity and the viscosity index were measured and calculated in accordance with ASTM D455. A lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less was judged to be pass.(2) Weight-average molecular weight (Mw), number-average molecular weight (Mn)

[0090] On a "2414 differential refractive index (RI) detector" equipped with a "1515 isocratic HPLC pump" manufactured by Waters Corporation, one column of "TSKguardcolumn SuperHZ-L" and two columns of "TSKSuperMultipore HZ-M" manufactured by Tosoh Corporation were installed in this order from the upstream side, and the weight-average molecular weight and the number-average molecular weight were measured under the conditions of a measurement temperature of 40°C, a mobile phase of tetrahydrofuran, a flow rate of 0.35 mL / min, and a sample concentration of 1.0 mg / mL and were determined in terms of standard polystyrene.(3) Amount of fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms and that containing hydrocarbon groups having 16 or more and less than 18 carbon atoms

[0091] A peak area of a fraction containing hydrocarbon groups having the respective carbon atoms within the range of 8 or more and less than 10 carbon atoms, that within the range of 10 or more and less than 12 carbon atoms, after this, the number of carbon atoms being increased by 2, and that up to within the range of 36 or more and less than 38 carbon atoms, were calculated using the following measurement device under the following measurement conditions, and a ratio of a peak area of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms to all the peak areas, and a ratio of a peak area of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms to all the peak areas were each calculated.(Measurement device)

[0092] Device: Shimadzu Corporation GC-2014 Type of detector: FID Column: packed column Filler: Silicone OV-1, 1.5%.Shinwasorb-S, 60 / 80 (Measurement conditions)

[0093] Injector temperature: 360°C Detector temperature: 360°C Temperature increase conditions: initial temperature 60°C Temperature increase rate: 10°C / min Temperature increase terminal temperature: 350°C Temperature increase terminal temperature retention time: 5 min Flow rate of gas: N 2 45 mL / min (4) NOACK 150°C

[0094] The value of NOACK 150°C was measured at 150°C for 12 hours in accordance with ASTM D5800. A lubricating oil composition having a NOACK 150°C value of 5 mass% or less was judged to be pass.(5) Friction coefficient[Evaluation of friction coefficient]

[0095] Using an SRV tester (manufactured by Optimol Instruments Pluftechnik, GmBH)), a friction coefficient obtained when a lubricating oil composition prepared was used was measured under the following conditions.

[0096] First, while increasing the temperature to 140°C from 30°C every 10°C, the test was carried out by performing sliding for 5 minutes at each temperature under the following conditions.

[0097] During the last one minute in the above test at 30°C, a friction coefficient was measured every one second, and an average value of the friction coefficients in the last one minute was calculated. Cylinder: AISI 52100 Mirror surface disc: AISI 52100 (maximum height roughness (Rz): less than 0.20 µm) Vibration frequency: 50 Hz Amplitude: 1.5 mm Load: 400 N Temperature: 30 to 140°C, temperature increase every 10°C Testing time: 5 minutes at each temperature

[0098] The friction coefficient was evaluated using, as an index, an improvement rate calculated from the following equation, on the basis of a friction coefficient at 30°C measured using a sample oil of Example 1. In Tables 1 and 2, "-" means that measurement of a friction coefficient was not carried out. Examples 1 to 18, Comparative examples 1 to 4

[0099] Lubricating oil compositions were each prepared by adding and mixing various components and other additives shown in Tables 1 and 2 in the blending amounts shown in Tables 1 and 2. The blending amount of the viscosity index improver in Tables 1 and 2 is described as a blending amount containing a diluent oil. Details of the components used in the preparation of the lubricating oil composition are as follows.<Component (A): base oil>

[0100] Base oil (A): base oil adjusted by using any one of base oils (1) to (22) described in Tables 1 and 2 so that the fraction in which the number of carbon atoms was 14 or more and less than 16 and the fraction in which the number of carbon atoms was 16 or more and less than 18 would become the values described in Tables 1 and 2. The base oils (1) to (22) each had a 100°C kinematic viscosity in the range of 2.61 to 4.45 mm 2< / s and a viscosity index in the range of 111 to 164.<Component (B): viscosity index improver>

[0101] Comb polymer (B1): comb polymer having a structure having, on a main chain, a large number of three-way branch points from which high-molecular weight side chains extend (Mw = 260,000, Mw / Mn = 3.1, resin content = 23%)<Component (C): friction modifier>

[0102] Ashless friction modifier (C1) (1): stearyl diethanolamine (Mw = 350, N content = 4.2 wt%, resin content = 99%) Ashless friction modifier (C1) (2): polymethacrylate (Mw = 9800, N content = 0.25 wt%, resin content = 78%). Ashless friction modifier (C1) (3): polymethacrylate (Mw = 18000, N content = 0.24 wt%, resin content = 67%). Ashless friction modifier (C1) (4): polymethacrylate (Mw = 57000, N content = 0.40 wt%, resin content = 33.2%) Molybdenum-based friction modifier (C2): molybdenum dithiocarbamate (MoDTC) (compound of the formula (1) wherein R 1< to R 4< are each independently a hydrocarbon group of 8 or 13, and X 1< to X 4< are each an oxygen atom; content of molybdenum atoms = 10.0 mass%, content of sulfur atoms = 11.5 mass%. <Other additives>

[0103] Additive mixture obtained by mixing a detergent, a dispersant, ZnDTP, an antioxidant, a metal deactivator, an anti-foaming agent, and a friction modifier.[Table 1]

[0104] Table 1ItemUnitExample 1Example 2Example 3Example 4Example 5Example 6Example 7Example 8Example 9Example 10Example 11Example 12Formulation of lubricating oil compositionBase oil (A)Base oil 1Mineral oilmass%84.4-----------Base oil 2Mineral oilmass%-83.5----------Base oil 3Mineral oil + Synthetic oilmass%--81.4---------Base oil 4Mineral oil + Synthetic oilmass%---80.4--------Base oil 5Mineral oilmass%----82.8-------Base oil 6Mineral oilmass%-----82.5------Base oil 7Mineral oilmass%------83.0-----Base oil 8Synthetic oilmass%-------80.4----Base oil 9Synthetic oilmass%--------79.6---Base oil 10Synthetic oilmass%---------78.4--Base oil 11Synthetic oilmass%----------71.2-Base oil 12Mineral oilmass%-----------75.4Base oil 13Mineral oilmass%------------Base oil 14Mineral oilmass%------------Base oil 15Mineral oilmass%------------Base oil 16Mineral oil + Synthetic oilmass%------------Base oil 17Mineral oilmass%------------Base oil 18Mineral oilmass%------------Base oil 19Mineral oilmass%------------Base oil 20Mineral oilmass%------------Base oil 21PAO(A1)mass%----------9.09.0Base oil 22Monoester (A2)mass%------------Viscosity index improver (B)Comb polymer (B1)mass%6.57.49.510.57.98.27.910.511.312.510.56.3Friction modifier (C)Ashless friction modifier (C1) (1)mass%------------Ashless friction modifier (C1) (2)mass%------------Ashless friction modifier (C1) (3)mass%------------Ashless friction modifier (C1) (4)mass%------------Molybdenum-based friction modifier (C2)mass%0.60.60.60.60.80.80.60.60.60.60.80.8Other additivesAdditive mixturemass%8.58.58.58.58.58.58.58.58.58.58.58.5Totalmass%100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0Fraction of hydrocarbon groups in base oilRatio of fraction of 14 or more and less than 16 carbon atoms to total amount of base oilmass%0.450.530.360.360.400.410.180.330.330.300.300.53Ratio of fraction of 16 or more and less than 18 carbon atoms to total amount of base oilmass%1.061.360.590.611.501.430.900.570.600.800.801.36Properties of lubricating oil compositionNOACK value at 150°Cmass%443355333434Kinematic viscosity at 40°Cmm 2< / s25.424.722.822.622.422.523.222.522.420.820.424.2Improvement rate of friction coefficient%0000---0--0- [Table 2]

[0105] Table 2ItemUnitComparative Example 1Comparative Example 2Comparative Example 3Comparative Example 4Example 13Example 14Example 15Example 16Example 17Example 18Formulation of lubricating oil compositionBase oil (A)Base oil 1Mineral oilmass%----------Base oil 2Mineral oilmass%----------Base oil 3Mineral oil + Synthetic oilmass%----------Base oil 4Mineral oil + Synthetic oilmass%----------Base oil 5Mineral oilmass%----------Base oil 6Mineral oilmass%----------Base oil 7Mineral oilmass%----------Base oil 8Synthetic oilmass%----------Base oil 9Synthetic oilmass%----------Base oil 10Synthetic oilmass%----------Base oil 11Synthetic oilmass%----------Base oil 12Mineral oilmass%----------Base oil 13Mineral oilmass%83.0---------Base oil 14Mineral oilmass%-83.2--------Base oil 15Mineral oilmass%--87.2-------Base oil 16Mineral oil + Synthetic oilmass%---78.1------Base oil 17Mineral oilmass%----83.0-----Base oil 18Mineral oilmass%-----75.975.9---Base oil 19Mineral oilmass%-------76.4--Base oil 20Mineral oilmass%--------83.083.0Base oil 21PAO(A1)mass%----------Base oil 22Monoester (A2)mass%-----8.08.08.0--Viscosity index improver (B)Comb polymer (B1)mass%7.77.53.512.67.46.56.56.57.47.4Friction modifier (C)Ashless friction modifier (C1) (1)mass%---------0.5Ashless friction modifier (C1) (2)mass%----0.50.5----Ashless friction modifier (C1) (3)mass%--------0.5-Ashless friction modifier (C1) (4)mass%------0.5---Molybdenum-based friction modifier (C2)mass%0.80.80.80.80.60.60.60.60.60.6Other additivesAdditive mixturemass%8.58.58.58.58.58.58.58.58.58.5Totalmass%100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0Fraction of hydrocarbon groups in base oilRatio of fraction of 14 or more and less than 16 carbon atoms to total amount of base oilmass%0.700.600.310.900.530.540.540.520.550.51Ratio of fraction of 16 or more and less than 18 carbon atoms to total amount of base oilmass%1.901.910.310.701.361.391.381.331.401.31Properties of lubricating oil compositionNOACK value at 150°Cmass%6626344443Kinematic viscosity at 40°Cmm 2< / s23.424.028.721.824.823.023.122.525.224.8Improvement rate of friction coefficient%0---140-3-29164

[0106] The results of Tables 1 and 2 show that the lubricating oil compositions of Examples 1 to 18 each including, as a base oil (A), a base oil in which the amount of the fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms was in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A) and the amount of the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms was in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A) each had a NOACK value at 150°C of 5 mass% or less and had a small amount of oil evaporation. In addition, the lubricating oil compositions of Examples 1 to 18 each had a kinematic viscosity at 40°C of 25 mm 2< / s or less and had excellent fuel consumption saving performance. On the other hand, the lubricating oil compositions of Comparative Examples 1 to 4 did not satisfy the acceptability criteria for the NOACK value at 150°C and the kinematic viscosity at 40°C.

Examples

examples

[0088]Next, the present invention will be described in much more detail with reference to Examples, but the present invention is in no way limited to these Examples. Various physical property values, etc. of the components used in Examples and Comparative Examples and the lubricating oil compositions obtained therein were measured in accordance with the methods described below.

(1) Kinematic viscosity and viscosity index

[0089]The kinematic viscosity and the viscosity index were measured and calculated in accordance with ASTM D455. A lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less was judged to be pass.

(2) Weight-average molecular weight (Mw), number-average molecular weight (Mn)

[0090]On a "2414 differential refractive index (RI) detector" equipped with a "1515 isocratic HPLC pump" manufactured by Waters Corporation, one column of "TSKguardcolumn SuperHZ-L" and two columns of "TSKSuperMultipore HZ-M" manufactured by Tosoh Corporation were instal...

examples 1 to 18

Examples 1 to 18, Comparative examples 1 to 4

[0099]Lubricating oil compositions were each prepared by adding and mixing various components and other additives shown in Tables 1 and 2 in the blending amounts shown in Tables 1 and 2. The blending amount of the viscosity index improver in Tables 1 and 2 is described as a blending amount containing a diluent oil. Details of the components used in the preparation of the lubricating oil composition are as follows.

[0100]Base oil (A): base oil adjusted by using any one of base oils (1) to (22) described in Tables 1 and 2 so that the fraction in which the number of carbon atoms was 14 or more and less than 16 and the fraction in which the number of carbon atoms was 16 or more and less than 18 would become the values described in Tables 1 and 2. The base oils (1) to (22) each had a 100°C kinematic viscosity in the range of 2.61 to 4.45 mm 2< / s and a viscosity index in the range of 111 to 164.

[0101]Comb polymer (B1): comb polymer having a str...

Technical Field

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

[0002] As an index of oil evaporability, a NOACK test at 250°C specified by ASTM D5800 has been widely used, but with advancement of engines, a correlation between the NOACK value and the amount of oil evaporation (amount of consumption) in an actual usage environment is not obtained occasionally. Under such circumstances, it has been reported that there is a correlation between the value of oil evaporability at lower temperatures and the amount of actual oil consumption (Non Patent Literature 1)Citation ListNon Patent LiteratureNon Patent Literature 1

[0003] Transactions of the Society of Automotive Engineers of Japan, Inc., Vol. 52, No. 6, November 2021Summary of InventionTechnical Problem

[0004] Under such circumstances, development of a lubricating oil composition which is reduced in the amount of oil evaporation at lower temperatures and is capable of improving fuel consumption saving performance has been desired.Solution to Problem

[0005] As a result of earnest studies, the present inventors have found that by using a base oil of specific fractions in a given amount, the above problem can be solved, and have completed the present invention.

[0006] That is, the present invention provides the following embodiment. [1] A lubricating oil composition comprising, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A). Advantageous Effects of Invention

[0007] One preferred embodiment of the present invention provides a lubricating oil composition which is reduced in the amount of oil evaporation at temperatures lower than 250°C. In addition, one preferred embodiment of the present invention provides a lubricating oil composition having a low kinematic viscosity at 40°C and capable of improving fuel consumption saving performance.Description of Embodiments

[0008] Regarding the numerical range described in the present specification, the upper limit and the lower limit can be combined freely. For example, with the description "preferably 30 to 100, more preferably 40 to 80" as numerical ranges, the range of "30 to 80" and the range of "40 to 100" are also included in the numerical ranges described in the present specification. Alternatively, for example, with the description "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less" as numerical ranges, the range of "30 to 80" and the range of "40 to 100" are also included in the numerical ranges described in the present specification.

[0009] In addition, for example, the description of "60 to 100" as a numerical range described in the present specification means a range of "60 or more (60 or more than 60) and 100 or less (100 or less than 100)".

[0010] The numerical range of a lower limit to an upper limit can be defined by appropriately selecting values from among respective options and optionally combining them in the definition of the upper limit and the lower limit described in the present specification.

[0011] In addition, a plurality of various requirements described in the present specification as preferred embodiments can be combined.[Constitution of lubricating oil composition]

[0012] The lubricating oil composition according to one embodiment of the present invention includes, as a base oil (A) (also referred to as a "component (A)" hereinafter), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A).

[0013] According to the present constitution, the NOACK value at 150°C can be set to less than the defined value, and therefore, a lubricating oil composition which is reduced in the amount of oil consumption even in an actual usage environment can be obtained. According to the present constitution, moreover, a lubricating oil composition having a low kinematic viscosity at 40°C and having excellent fuel consumption saving performance can be obtained.

[0014] In the present specification, the NOACK value at 150°C means a value measured at 150°C for 12 hours in accordance with ASTM D5800 (also referred to as NOACK 150°C hereinafter).

[0015] Hereinafter, details of each component contained in the lubricating oil composition according to one embodiment of the present invention will be described.<Component (A): base oil>

[0016] The lubricating oil composition of the present invention uses, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A). By setting the amounts of the individual fractions of the base oil (A) to the above ranges, the value of NOACK 150°C can be adjusted to 5 mass% or less, and the oil consumption in an actual engine usage environment can be improved. In addition, by setting the amounts of the individual fractions of the base oil (A) to the above ranges, a lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less and having excellent fuel consumption saving performance can be obtained.

[0017] The amount of the fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is preferably 0.10 mass% or more, 0.15 mass% or more, and 0.60 mass% or less, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved.

[0018] The amount of the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms is preferably 0.35 mass% or more, 0.40 mass% or more, 0.50 mass% or more, while it is preferably 1.85 mass% or less, 1.80 mass% or less, 1.70 mass% or less, 1.60 mass% or less, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved.

[0019] As such a base oil (A) as above, employable is a base oil in which the amounts of the fractions are set according to the ranges of the individual fractions containing hydrocarbon groups having the above numbers of carbon atoms based on the measurement results of the individual fractions measured by the method described in Examples described later.

[0020] The base oil (A) of the present invention can be manufactured by, for example, making a combination of mineral oils described below, a combination of synthetic oils, or a combination of a mineral oil and a synthetic oil, and keeping the individual fractions containing hydrocarbon groups having the above numbers of carbon atoms within the above ranges taking into consideration the measurement results of the individual fractions measured by the method described in Examples described later.

[0021] The fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms and the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms contained in the lubricating oil composition of the present invention are those obtained by, for example, mixing a mineral oil and / or a synthetic oil so as to contain hydrocarbon groups of the above numbers of carbon atoms. Examples of the mineral oils to constitute the fractions include atmospheric residual oils obtained by subjecting crude oils, such as paraffinic crude oils, intermediate base crude oils, and naphthenic crude oils, to atmospheric distillation; distillates obtained by subjecting these atmospheric residual oils to vacuum distillation; and refined oils obtained by subjecting the distillates to one or more of refining treatments, such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0022] The base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be a base oil using one of these mineral oils singly, or may be a mixed oil using a plurality of mineral oils in combination.

[0023] The base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be one using one synthetic oil singly, or may be a mixed oil using a plurality of synthetic oils in combination. Furthermore, the base oil (A) for use in the lubricating oil composition according to one embodiment of the present invention may be a mixed oil using a mineral oil and a synthetic oil in combination. Examples of the synthetic oils include α-olefins, and poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffin; polyalkylene glycol; ether-based oils, such as polyphenyl ether; ester-based oils, such as polyol esters, dibasic acid esters, and monoesters; alkylbenzene; alkylnaphthalene; synthetic oils (GTL) obtained by isomerizing waxes (GTL waxes (Gas To Liquids WAX)) produced from natural gas through Fischer-Tropsch process or the like; and synthetic oils (Ethylene To Liquid (ETL)) obtained by oligomerizing olefins produced from a gas as a raw material. These synthetic oils may be produced from recyclable resources.

[0024] Among these, the base oil for use in one embodiment of the present invention preferably contains at least one selected from mineral oils and synthetic oils classified into Group 2 and Group 3 in the API (American Petroleum Institute) base oil category.

[0025] The lubricating oil composition according to one embodiment of the present invention preferably further contains at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2). Since these base oils are contained, a lubricating oil composition satisfying the value of NOACK 150°C and capable of improving fuel consumption saving performance can be obtained.

[0026] Specific examples of the poly-α-olefins (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).

[0027] Specific examples of the ester-based oils (A2) include the above-mentioned polyol esters, dibasic acid esters, and monoesters. More specific examples of the ester-based oils (A1) include trimethylolpropane tridecanoate, 2-ethylhexyl palmitate, and bis(2-ethylhexyl) sebacate.

[0028] When one embodiment of the present invention contains, as the base oil (A), at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2), the content of the poly-α-olefin (A1) or the ester-based oil (A2) contained or a mixture of these is preferably 3.0 mass% or more, more preferably 5.0 mass% or more, much more preferably 7.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint that the value of NOACK 150°C is satisfied and the fuel consumption saving performance is improved, and it is preferably 10.0 mass% or less, more preferably 9.0 mass% or less, from the viewpoint of suppressing deterioration of a rubber material.

[0029] The kinematic viscosity at 100°C of the base oil (A) for use in one embodiment of the present invention is preferably 2.5 mm 2< / s or more, more preferably 2.8 mm 2< / s or more, much more preferably 3.0 mm 2< / s or more, and preferably 4.5 mm 2< / s or less, more preferably 4.1 mm 2< / s or less, much more preferably 2.8 mm 2< / s or less.

[0030] The kinematic viscosity at 100°C of the base oil (A) is preferably 2.5 mm 2< / s or more because of retention of oil films. On the other hand, the kinematic viscosity at 100°C of the base oil (A) is preferably 4.5 mm 2< / s or less because power loss due to the viscous resistance can be suppressed, and the fuel consumption improving effect can be achieved. When a mixed oil is used as the base oil (A) in one embodiment of the present invention, the kinematic viscosity at 100°C of the mixed oil is preferably in the above ranges.

[0031] The viscosity index of the base oil for use in one embodiment of the present invention is preferably 80 or more, more preferably 90 or more, much more preferably 100 or more, even more preferably 110 or more, from the viewpoint of suppressing the viscosity change due to the temperature change and improving the fuel consumption saving performance.

[0032] In the present specification, the kinematic viscosity and the viscosity index mean values measured or calculated in accordance with ASTM D455.

[0033] In the lubricating oil composition according to one embodiment of the present invention, the content of the base oil (A) is 70 mass% or more, 75 mass% or more, and 99.9 mass% or less, 98 mass% or less, 95 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.<Component (B): viscosity index improver>

[0034] The lubricating oil composition according to one embodiment of the present invention further contains a viscosity index improver (B) containing a comb polymer (B1). Since the comb polymer (B1) is contained as the viscosity index improver (B), the fuel consumption saving performance of the lubricating oil composition can be improved. The comb polymer (B1) suffices if it is a polymer having a structure having, on a main chain, a large number of three-way branch points from which high-molecular weight side chains extend. The comb polymer (B1) for use in one embodiment of the present invention is preferably a polymer having at least a constitutional unit (X1) derived from a macromonomer (x1). This constitutional unit (X1) corresponds to the above-mentioned "high-molecular weight side chain".

[0035] In the present invention, the "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 the terminal.

[0036] The comb polymer (B1) for use in one embodiment of the present invention may be a homopolymer composed only of a constitutional unit (X1) derived from one kind of macromonomer (x1), or may be a copolymer containing a constitutional unit (X1) derived from two or more kinds of macromonomers (x1).

[0037] Further, the comb polymer (B1) for use in one embodiment of the present invention may be a copolymer containing, together with the constitutional unit derived from the macromonomer (x1), a constitutional unit (X2) derived from a monomer other than the macromonomer (x1).

[0038] Regarding the specific structure of such a comb polymer, preferable is a copolymer having a side chain containing the constitutional unit (X1) derived from the macromonomer (x1) on a main chain containing the constitutional unit (X2) derived from a monomer (x2).

[0039] Examples of the monomers (x2) include alkyl (meth)acrylates, nitrogen atom-containing vinyl monomers, hydroxyl group-containing vinyl monomers, phosphorus atom-containing monomers, aliphatic hydrocarbon-based vinyl monomers, alicyclic hydrocarbon-based 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-based vinyl monomers.

[0040] In the present specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are values in terms of standard polystyrene, which are measured by gel permeation chromatography (GPC) .

[0041] In the lubricating oil composition according to 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, much more preferably 6.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of improving the fuel consumption saving performance. The content of the comb polymer (B1) is preferably 14.0 mass% or less, more preferably 13.0 mass% or less, much more preferably 12.5 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.

[0042] The viscosity index improver (B) for use in one embodiment of the present invention may or may not contain viscosity index improvers composed of polymers other than the above-mentioned comb polymer (B1) as long as the effects of the present invention are not impaired.

[0043] Examples of such polymers include polymers not corresponding to the comb polymers, such as polymethacrylate, dispersed polymethacrylate, olefin copolymers (for example, ethylene-propylene copolymer), dispersed olefin copolymers, and styrene copolymers (for example, styrene-diene copolymer, styrene-isoprene copolymer).<Component (C): friction modifier)

[0044] The lubricating oil composition according to one embodiment of the present invention further contains at least one friction modifier (C) selected from the group consisting of an ashless friction modifier (C1) and a molybdenum-based friction modifier (C2). Since the above friction modifier (C) is contained, a lubricating oil composition having excellent friction characteristics can be obtained. From the viewpoint of more improving the friction characteristics, the lubricating oil composition according to one embodiment of the present invention contains both the ashless friction modifier (C1) and the molybdenum-based friction modifier (C2) as the friction modifiers (C).<Ashless friction modifier (C1)>

[0045] The ashless friction modifier (C1) for use in one embodiment of the present invention is not particularly restricted, and examples thereof include ashless friction modifiers (C1), such as amine compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea-based compounds, and hydrazide-based compounds. The ashless friction modifier (C1) may be used singly or in combination of two or more.

[0046] Since the ashless friction modifier (C1) is contained, a lubricating oil composition having excellent friction characteristics can be obtained, and besides, even if the lubricating oil composition according to one embodiment of the present invention contains an ester-based oil (A2) as the base oil (A), the friction characteristics can be favorably maintained by blending the ashless friction modifier (C1) having a specific weight-average molecular weight (Mw), and as a result, the fuel consumption saving performance can be favorably maintained.

[0047] In one embodiment of the present invention, the weight-average molecular weight (Mw) of the ashless friction modifier (C1) is preferably 100 or more and less than 50,000, 100 or more and less than 10,000, 100 or more and less than 1000, 1000 or more and less than 10,000, or 10,000 or more and less than 50,000, and more preferably 1000 or more and less than 50,000, from the viewpoint of improving friction characteristics.

[0048] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition having excellent friction characteristics, the total content of the ashless friction modifier (C1) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, much more preferably 0.3 mass% or more, and may be 1.0 mass% or less, 0.8 mass% or less, 0.5 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.<Molybdenum-based friction modifier (C2)>

[0049] Examples of the molybdenum-based friction modifiers (C2) for use in one embodiment of the present invention include molybdenum-based compounds, such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid. The molybdenum-based friction modifier (C2) may be used singly or in combination of two or more.

[0050] The lubricating oil composition according to one embodiment of the present invention preferably contains, among the above compounds, molybdenum dithiocarbamate (MoDTC) as the molybdenum-based frication modifier (C2).<<Molybdenum dithiocarbamate (MoDTC) >>

[0051] The molybdenum dithiocarbamate (MoDTC) for use in one embodiment of the present invention is, for example, a compound represented by the following general formula (1).

[0052] In the formula (1), R 1< to R 4< are each independently a hydrocarbon group having 4 to 18 carbon atoms, 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.

[0053] Examples of the alkyl groups 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.

[0054] Examples of the alkenyl groups 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.

[0055] Examples of the cycloalkyl groups 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.

[0056] Examples of the aryl groups having 6 to 18 carbon atoms include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and a terphenyl group.

[0057] Examples of the alkylaryl groups 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.

[0058] Examples of the arylalkyl groups having 7 to 18 carbon atoms include a phenylmethyl group, a phenylethyl group, and a diphenylmethyl group.

[0059] In one embodiment of the present invention, the content of the molybdenum dithiocarbamate (MoDTC) is preferably 0.3 mass% or more, more preferably 0.5 mass% or more, much more preferably 0.6 mass% or more, and may be 1.0 mass% or less, 0.9 mass% or less, 0.8 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of obtaining a lubricating oil composition having excellent friction characteristics.<Various additives>

[0060] The lubricating oil composition according to one embodiment of the present invention may contain various additives when needed, as long as the effects of the present invention are not impaired.

[0061] Examples of such various additives include pour point depressants, antioxidants, metal-based detergents, ashless dispersants, antiwear agents, rust inhibitors, anti-foaming agents, and extreme-pressure additives.

[0062] These lubricating oil additives may be each used singly, or may be each used in combination of two or more.

[0063] The content of each of these various additives can be appropriately adjusted as long as the effects of the present invention are not impaired, but the contents of these additives are each independently usually 0.001 to 15 mass%, preferably 0.005 to 10 mass%, more preferably 0.01 to 5 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0064] A compound having a plurality of functions of the above additives (for example, a compound having functions of an antiwear agent and an extreme-pressure additive) may be used.[Pour point depressant]

[0065] The lubricating oil composition according to one embodiment of the present invention may further contain a pour point depressant. The pour point depressant may be used singly, or may be used in combination of two or more.

[0066] Examples of the pour point depressants for use in one embodiment of the present invention include an ethylene-vinyl acetate copolymer, condensates of chlorinated paraffins and naphthalene, condensates of chlorinated paraffins and phenol, polymethacrylates, and polyalkylstyrenes.[Antioxidant]

[0067] The lubricating oil composition according to one embodiment of the present invention may further contain an antioxidant. The antioxidant may be used singly, or may be used in combination of two or more.

[0068] Examples of the antioxidants for use 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.[Metal-based detergent]

[0069] The lubricating oil composition according to one embodiment of the present invention may further contain a metal-based detergent. The metal-based detergent may be used singly, or may be used in combination of two or more.

[0070] Examples of the metal-based detergents for use in one embodiment of the present invention include metal salts, such as metal sulfonates, metal salicylates, and metal phenates. As a metal atom to constitute the metal salts is preferably a metal atom selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and much more preferably calcium or magnesium.[Ashless dispersant]

[0071] The lubricating oil composition according to one embodiment of the present invention may further contain an ashless dispersant. The ashless dispersant may be used singly, or may be used in combination of two or more.

[0072] The ashless dispersant for use in one embodiment of the present invention is preferably an alkenyl succinimide, and may be a modified alkenyl succinimide obtained by reacting an alkenyl succinimide with one or more selected from boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, organic acids, and the like.[Antiwear agent]

[0073] The lubricating oil composition according to one embodiment of the present invention may further contain an antiwear agent. The antiwear agent may be used singly, or may be used in combination of two or more.

[0074] Examples of the antiwear agents for use in one embodiment of the present invention include sulfur-containing compounds, such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds, such as phosphite esters, phosphate esters, phosphonate esters, and amine salts or metal salts of these; and sulfur-containing and phosphorus-containing antiwear agents, such as thiophosphite esters, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts of these.[Rust inhibitor]

[0075] The lubricating oil composition according to one embodiment of the present invention may further contain a rust inhibitor. The rust inhibitor may be used singly, or may be used in combination of two or more.

[0076] Examples of the rust inhibitors for use 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, oxidized paraffin, and polyoxyethylene alkyl ethers.[Anti-foaming agent]

[0077] The lubricating oil composition according to one embodiment of the present invention may further contain an anti-foaming agent. The anti-foaming agent may be used singly, or may be used in combination of two or more.

[0078] Examples of the anti-foaming agents for use in one embodiment of the present invention include alkyl silicone-based anti-foaming agents, fluorosilicone-based anti-foaming agents, and fluoroalkyl ether-based anti-foaming agents.[Extreme-pressure additive]

[0079] The lubricating oil composition according to one embodiment of the present invention may further contain an extreme-pressure additive. The extreme-pressure additive may be used singly, or may be used in combination of two or more.

[0080] Examples of the extreme-pressure additives for use in one embodiment of the present invention include sulfur-containing compounds, such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds, such as phosphite esters, phosphate esters, phosphonate esters, and amine salts or metal salts of these; and sulfur-containing and phosphorus-containing antiwear agents, such as thiophosphite esters, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts of these.(Method for producing lubricating oil composition)

[0081] The method for producing a lubricating oil composition according to one embodiment of the present invention is not particularly restricted, but is preferably a method including a step of blending, with the base oil (A), other various additives when needed. The order of blending the components can be appropriately set.[Properties of lubricating oil composition]

[0082] The kinematic viscosity at 100°C of the lubricating oil composition according to one embodiment of the present invention is preferably 5.0 mm 2< / s or more, more preferably 5.5 mm 2< / s or more, much more preferably 6.1 mm 2< / s or more, and preferably 12.5 mm 2< / s or less, more preferably 10.0 mm 2< / s or less, much more preferably 9.3 mm 2< / s or less.

[0083] The NOACK value of the lubricating oil composition according to one embodiment of the present invention, as measured at 150°C for 12 hours in accordance with ASTM D5800, is preferably 5 mass% or less, and the lower limit is not particularly limited, but is, for example, 3 mass% or more.

[0084] The value of friction coefficient, as measured by the method described in Examples described later using the lubricating oil composition according to one embodiment of the present invention as a sample oil, is preferably 0.110 or less, more preferably 0.106 or less, much more preferably less than 0.085, even more preferably 0.084 or less. The lubricating oil composition having a value of friction coefficient in the above range can be said to be excellent in friction characteristics.[Applications of lubricating oil composition]

[0085] The lubricating oil composition of the present invention is reduced in the amount of oil evaporation that uses the NOACK vale at 150°C as an index, and hence, it can be suitably used for lubrication of internal combustion engines.

[0086] On that account, the present invention also provides an internal combustion engine set forth in [I] below and a method of using a lubricating oil composition set forth in [II] below. [I] An internal combustion engine filled with the above-mentioned lubricating oil composition according to one embodiment of the present invention. [II] A method of using a lubricating oil composition, in which the above-mentioned lubricating oil composition according to one embodiment of the present invention is applied to lubrication of an internal combustion engine.

[0087] The present invention can include the following embodiments. [1] A lubricating oil composition comprising, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms 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 ashless friction modifier (C1) has a weight-average molecular weight (Mw) of 100 or more and less than 50,000. [3] The lubricating oil composition according to [1], comprising an ashless friction modifier (C1), wherein the ashless friction modifier (C1) has 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 [1] to [3], further comprising, as the base oil (A), at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2). [5] The lubricating oil composition according to [4], comprising, as the base oil (A), an ester-based oil (A2). [6] The lubricating oil composition according to any one of [1] to [5], further comprising a viscosity index improver (B) containing 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

[0088] Next, the present invention will be described in much more detail with reference to Examples, but the present invention is in no way limited to these Examples. Various physical property values, etc. of the components used in Examples and Comparative Examples and the lubricating oil compositions obtained therein were measured in accordance with the methods described below.(1) Kinematic viscosity and viscosity index

[0089] The kinematic viscosity and the viscosity index were measured and calculated in accordance with ASTM D455. A lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less was judged to be pass.(2) Weight-average molecular weight (Mw), number-average molecular weight (Mn)

[0090] On a "2414 differential refractive index (RI) detector" equipped with a "1515 isocratic HPLC pump" manufactured by Waters Corporation, one column of "TSKguardcolumn SuperHZ-L" and two columns of "TSKSuperMultipore HZ-M" manufactured by Tosoh Corporation were installed in this order from the upstream side, and the weight-average molecular weight and the number-average molecular weight were measured under the conditions of a measurement temperature of 40°C, a mobile phase of tetrahydrofuran, a flow rate of 0.35 mL / min, and a sample concentration of 1.0 mg / mL and were determined in terms of standard polystyrene.(3) Amount of fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms and that containing hydrocarbon groups having 16 or more and less than 18 carbon atoms

[0091] A peak area of a fraction containing hydrocarbon groups having the respective carbon atoms within the range of 8 or more and less than 10 carbon atoms, that within the range of 10 or more and less than 12 carbon atoms, after this, the number of carbon atoms being increased by 2, and that up to within the range of 36 or more and less than 38 carbon atoms, were calculated using the following measurement device under the following measurement conditions, and a ratio of a peak area of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms to all the peak areas, and a ratio of a peak area of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms to all the peak areas were each calculated.(Measurement device)

[0092] Device: Shimadzu Corporation GC-2014 Type of detector: FID Column: packed column Filler: Silicone OV-1, 1.5%.Shinwasorb-S, 60 / 80 (Measurement conditions)

[0093] Injector temperature: 360°C Detector temperature: 360°C Temperature increase conditions: initial temperature 60°C Temperature increase rate: 10°C / min Temperature increase terminal temperature: 350°C Temperature increase terminal temperature retention time: 5 min Flow rate of gas: N 2 45 mL / min (4) NOACK 150°C

[0094] The value of NOACK 150°C was measured at 150°C for 12 hours in accordance with ASTM D5800. A lubricating oil composition having a NOACK 150°C value of 5 mass% or less was judged to be pass.(5) Friction coefficient[Evaluation of friction coefficient]

[0095] Using an SRV tester (manufactured by Optimol Instruments Pluftechnik, GmBH)), a friction coefficient obtained when a lubricating oil composition prepared was used was measured under the following conditions.

[0096] First, while increasing the temperature to 140°C from 30°C every 10°C, the test was carried out by performing sliding for 5 minutes at each temperature under the following conditions.

[0097] During the last one minute in the above test at 30°C, a friction coefficient was measured every one second, and an average value of the friction coefficients in the last one minute was calculated. Cylinder: AISI 52100 Mirror surface disc: AISI 52100 (maximum height roughness (Rz): less than 0.20 µm) Vibration frequency: 50 Hz Amplitude: 1.5 mm Load: 400 N Temperature: 30 to 140°C, temperature increase every 10°C Testing time: 5 minutes at each temperature

[0098] The friction coefficient was evaluated using, as an index, an improvement rate calculated from the following equation, on the basis of a friction coefficient at 30°C measured using a sample oil of Example 1. In Tables 1 and 2, "-" means that measurement of a friction coefficient was not carried out. Examples 1 to 18, Comparative examples 1 to 4

[0099] Lubricating oil compositions were each prepared by adding and mixing various components and other additives shown in Tables 1 and 2 in the blending amounts shown in Tables 1 and 2. The blending amount of the viscosity index improver in Tables 1 and 2 is described as a blending amount containing a diluent oil. Details of the components used in the preparation of the lubricating oil composition are as follows.<Component (A): base oil>

[0100] Base oil (A): base oil adjusted by using any one of base oils (1) to (22) described in Tables 1 and 2 so that the fraction in which the number of carbon atoms was 14 or more and less than 16 and the fraction in which the number of carbon atoms was 16 or more and less than 18 would become the values described in Tables 1 and 2. The base oils (1) to (22) each had a 100°C kinematic viscosity in the range of 2.61 to 4.45 mm 2< / s and a viscosity index in the range of 111 to 164.<Component (B): viscosity index improver>

[0101] Comb polymer (B1): comb polymer having a structure having, on a main chain, a large number of three-way branch points from which high-molecular weight side chains extend (Mw = 260,000, Mw / Mn = 3.1, resin content = 23%)<Component (C): friction modifier>

[0102] Ashless friction modifier (C1) (1): stearyl diethanolamine (Mw = 350, N content = 4.2 wt%, resin content = 99%) Ashless friction modifier (C1) (2): polymethacrylate (Mw = 9800, N content = 0.25 wt%, resin content = 78%). Ashless friction modifier (C1) (3): polymethacrylate (Mw = 18000, N content = 0.24 wt%, resin content = 67%). Ashless friction modifier (C1) (4): polymethacrylate (Mw = 57000, N content = 0.40 wt%, resin content = 33.2%) Molybdenum-based friction modifier (C2): molybdenum dithiocarbamate (MoDTC) (compound of the formula (1) wherein R 1< to R 4< are each independently a hydrocarbon group of 8 or 13, and X 1< to X 4< are each an oxygen atom; content of molybdenum atoms = 10.0 mass%, content of sulfur atoms = 11.5 mass%. <Other additives>

[0103] Additive mixture obtained by mixing a detergent, a dispersant, ZnDTP, an antioxidant, a metal deactivator, an anti-foaming agent, and a friction modifier.[Table 1]

[0104] Table 1ItemUnitExample 1Example 2Example 3Example 4Example 5Example 6Example 7Example 8Example 9Example 10Example 11Example 12Formulation of lubricating oil compositionBase oil (A)Base oil 1Mineral oilmass%84.4-----------Base oil 2Mineral oilmass%-83.5----------Base oil 3Mineral oil + Synthetic oilmass%--81.4---------Base oil 4Mineral oil + Synthetic oilmass%---80.4--------Base oil 5Mineral oilmass%----82.8-------Base oil 6Mineral oilmass%-----82.5------Base oil 7Mineral oilmass%------83.0-----Base oil 8Synthetic oilmass%-------80.4----Base oil 9Synthetic oilmass%--------79.6---Base oil 10Synthetic oilmass%---------78.4--Base oil 11Synthetic oilmass%----------71.2-Base oil 12Mineral oilmass%-----------75.4Base oil 13Mineral oilmass%------------Base oil 14Mineral oilmass%------------Base oil 15Mineral oilmass%------------Base oil 16Mineral oil + Synthetic oilmass%------------Base oil 17Mineral oilmass%------------Base oil 18Mineral oilmass%------------Base oil 19Mineral oilmass%------------Base oil 20Mineral oilmass%------------Base oil 21PAO(A1)mass%----------9.09.0Base oil 22Monoester (A2)mass%------------Viscosity index improver (B)Comb polymer (B1)mass%6.57.49.510.57.98.27.910.511.312.510.56.3Friction modifier (C)Ashless friction modifier (C1) (1)mass%------------Ashless friction modifier (C1) (2)mass%------------Ashless friction modifier (C1) (3)mass%------------Ashless friction modifier (C1) (4)mass%------------Molybdenum-based friction modifier (C2)mass%0.60.60.60.60.80.80.60.60.60.60.80.8Other additivesAdditive mixturemass%8.58.58.58.58.58.58.58.58.58.58.58.5Totalmass%100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0Fraction of hydrocarbon groups in base oilRatio of fraction of 14 or more and less than 16 carbon atoms to total amount of base oilmass%0.450.530.360.360.400.410.180.330.330.300.300.53Ratio of fraction of 16 or more and less than 18 carbon atoms to total amount of base oilmass%1.061.360.590.611.501.430.900.570.600.800.801.36Properties of lubricating oil compositionNOACK value at 150°Cmass%443355333434Kinematic viscosity at 40°Cmm 2< / s25.424.722.822.622.422.523.222.522.420.820.424.2Improvement rate of friction coefficient%0000---0--0- [Table 2]

[0105] Table 2ItemUnitComparative Example 1Comparative Example 2Comparative Example 3Comparative Example 4Example 13Example 14Example 15Example 16Example 17Example 18Formulation of lubricating oil compositionBase oil (A)Base oil 1Mineral oilmass%----------Base oil 2Mineral oilmass%----------Base oil 3Mineral oil + Synthetic oilmass%----------Base oil 4Mineral oil + Synthetic oilmass%----------Base oil 5Mineral oilmass%----------Base oil 6Mineral oilmass%----------Base oil 7Mineral oilmass%----------Base oil 8Synthetic oilmass%----------Base oil 9Synthetic oilmass%----------Base oil 10Synthetic oilmass%----------Base oil 11Synthetic oilmass%----------Base oil 12Mineral oilmass%----------Base oil 13Mineral oilmass%83.0---------Base oil 14Mineral oilmass%-83.2--------Base oil 15Mineral oilmass%--87.2-------Base oil 16Mineral oil + Synthetic oilmass%---78.1------Base oil 17Mineral oilmass%----83.0-----Base oil 18Mineral oilmass%-----75.975.9---Base oil 19Mineral oilmass%-------76.4--Base oil 20Mineral oilmass%--------83.083.0Base oil 21PAO(A1)mass%----------Base oil 22Monoester (A2)mass%-----8.08.08.0--Viscosity index improver (B)Comb polymer (B1)mass%7.77.53.512.67.46.56.56.57.47.4Friction modifier (C)Ashless friction modifier (C1) (1)mass%---------0.5Ashless friction modifier (C1) (2)mass%----0.50.5----Ashless friction modifier (C1) (3)mass%--------0.5-Ashless friction modifier (C1) (4)mass%------0.5---Molybdenum-based friction modifier (C2)mass%0.80.80.80.80.60.60.60.60.60.6Other additivesAdditive mixturemass%8.58.58.58.58.58.58.58.58.58.5Totalmass%100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0Fraction of hydrocarbon groups in base oilRatio of fraction of 14 or more and less than 16 carbon atoms to total amount of base oilmass%0.700.600.310.900.530.540.540.520.550.51Ratio of fraction of 16 or more and less than 18 carbon atoms to total amount of base oilmass%1.901.910.310.701.361.391.381.331.401.31Properties of lubricating oil compositionNOACK value at 150°Cmass%6626344443Kinematic viscosity at 40°Cmm 2< / s23.424.028.721.824.823.023.122.525.224.8Improvement rate of friction coefficient%0---140-3-29164

[0106] The results of Tables 1 and 2 show that the lubricating oil compositions of Examples 1 to 18 each including, as a base oil (A), a base oil in which the amount of the fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms was in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A) and the amount of the fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms was in the range of 0.35 to 1.85 mass% based on the total amount of the base oil (A) each had a NOACK value at 150°C of 5 mass% or less and had a small amount of oil evaporation. In addition, the lubricating oil compositions of Examples 1 to 18 each had a kinematic viscosity at 40°C of 25 mm 2< / s or less and had excellent fuel consumption saving performance. On the other hand, the lubricating oil compositions of Comparative Examples 1 to 4 did not satisfy the acceptability criteria for the NOACK value at 150°C and the kinematic viscosity at 40°C.

Examples

examples

[0088]Next, the present invention will be described in much more detail with reference to Examples, but the present invention is in no way limited to these Examples. Various physical property values, etc. of the components used in Examples and Comparative Examples and the lubricating oil compositions obtained therein were measured in accordance with the methods described below.

(1) Kinematic viscosity and viscosity index

[0089]The kinematic viscosity and the viscosity index were measured and calculated in accordance with ASTM D455. A lubricating oil composition having a kinematic viscosity at 40°C of 25 mm 2< / s or less was judged to be pass.

(2) Weight-average molecular weight (Mw), number-average molecular weight (Mn)

[0090]On a "2414 differential refractive index (RI) detector" equipped with a "1515 isocratic HPLC pump" manufactured by Waters Corporation, one column of "TSKguardcolumn SuperHZ-L" and two columns of "TSKSuperMultipore HZ-M" manufactured by Tosoh Corporation were instal...

examples 1 to 18

Examples 1 to 18, Comparative examples 1 to 4

[0099]Lubricating oil compositions were each prepared by adding and mixing various components and other additives shown in Tables 1 and 2 in the blending amounts shown in Tables 1 and 2. The blending amount of the viscosity index improver in Tables 1 and 2 is described as a blending amount containing a diluent oil. Details of the components used in the preparation of the lubricating oil composition are as follows.

[0100]Base oil (A): base oil adjusted by using any one of base oils (1) to (22) described in Tables 1 and 2 so that the fraction in which the number of carbon atoms was 14 or more and less than 16 and the fraction in which the number of carbon atoms was 16 or more and less than 18 would become the values described in Tables 1 and 2. The base oils (1) to (22) each had a 100°C kinematic viscosity in the range of 2.61 to 4.45 mm 2< / s and a viscosity index in the range of 111 to 164.

[0101]Comb polymer (B1): comb polymer having a str...

Claims

1. A lubricating oil composition comprising, as a base oil (A), a base oil in which the amount of a fraction containing hydrocarbon groups having 14 or more and less than 16 carbon atoms is in the range of 0.10 to 0.60 mass% based on the total amount of the base oil (A), and the amount of a fraction containing hydrocarbon groups having 16 or more and less than 18 carbon atoms 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 claim 1, comprising an ashless friction modifier (C1), wherein the ashless friction modifier (C1) has a weight-average molecular weight (Mw) of 100 or more and less than 50,000.

3. The lubricating oil composition according to claim 1, comprising an ashless friction modifier (C1), wherein the ashless friction modifier (C1) has 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), at least one base oil selected from the group consisting of poly-α-olefin (A1) and an ester-based oil (A2).

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

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