Lubricating oil composition

Abstract

It is desirable to develop a lubricating oil composition having a low oil evaporation amount at lower temperatures and capable of improving fuel efficiency. The lubricating oil composition contains, as the base oil (A), a base oil in which a fraction containing a hydrocarbon group having 14 or more carbon atoms but less than 16 is in the range of 0.10-0.60 mass% based on the total amount of the base oil (A) and a fraction containing a hydrocarbon group having 16 or more carbon atoms but less than 18 is in the range of 0.35-1.85 mass% based on the total amount of the base oil (A).

Description

Technical Field

[0001] This invention relates to lubricating oil compositions. Background Technology

[0002] As an indicator of oil volatility, the NOACK test at 250°C as specified in ASTM D5800 is widely used. However, with the increasing sophistication of engines, the correlation between the NOACK value and the oil evaporation (consumption) under actual operating conditions is sometimes not obtained. In this case, there are reports that the oil volatility value at lower temperatures is correlated with the actual fuel consumption (Non-Patent Literature 1).

[0003] Existing technical documents Non-patent literature Non-patent document 1: Proceedings of the Automotive Technology Conference, Vol.52, No.6, November 2021. Summary of the Invention

[0004] The problem that the invention aims to solve Under these circumstances, it is desirable to develop lubricant compositions that reduce oil evaporation at lower temperatures and improve fuel efficiency.

[0005] Methods for solving problems Through repeated and in-depth research, the inventors discovered that by using a specified amount of base oil of a specific fraction, the above-mentioned problems could be solved, thus completing this invention.

[0006] That is, the present invention provides the following method.

[0007] [1] A lubricating oil composition, wherein, as a base oil (A), it comprises: a fraction containing hydrocarbon groups having 14 or more carbon atoms and less than 16 carbon atoms in a range of 0.10 to 0.60% by mass based on the total amount of base oil (A), and a fraction containing hydrocarbon groups having 16 or more carbon atoms and less than 18 carbon atoms in a range of 0.35 to 1.85% by mass based on the total amount of base oil (A).

[0008] Invention Effects One suitable embodiment of the present invention provides a lubricating oil composition with low oil evaporation at temperatures lower than 250°C. Additionally, another suitable embodiment of the present invention provides a lubricating oil composition with low kinematic viscosity at 40°C, which improves fuel efficiency. Detailed Implementation

[0009] The upper and lower limits of the numerical ranges described in this specification can be combined arbitrarily. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80", the range of "30 to 80" and the range of "40 to 100" are also included in the numerical range described in this specification. Furthermore, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less", the range of "30 to 80" and the range of "40 to 100" are also included in the numerical range described in this specification.

[0010] Furthermore, the numerical range described in this specification, such as "60~100", refers to the range of "60 or more (60 or more) and 100 or less (100 or less)".

[0011] Furthermore, the upper and lower limits specified in this specification can be appropriately selected and arbitrarily combined from various options to define the numerical range of the lower and upper limits.

[0012] Furthermore, the various conditions described as preferred embodiments in this specification can be combined in multiple ways.

[0013] [Composition of the lubricating oil composition] In one embodiment of the present invention, the lubricating oil composition comprises, as base oil (A) (hereinafter also referred to as "component (A)"), a fraction containing hydrocarbon groups having 14 or more but less than 16 carbon atoms in a range of 0.10 to 0.60% by mass based on the total amount of base oil (A), and a fraction containing hydrocarbon groups having 16 or more but less than 18 carbon atoms in a range of 0.35 to 1.85% by mass based on the total amount of base oil (A).

[0014] According to this configuration, the NOACK value at 150°C can be less than a specified value, thus obtaining a lubricating oil composition with low oil consumption even under actual operating conditions. Furthermore, according to this configuration, a lubricating oil composition with low kinematic viscosity at 40°C and excellent fuel efficiency can be obtained.

[0015] It should be noted that, in this specification, the NOACK value at 150°C refers to the value measured according to ASTM D5800 at 150°C for 12 hours (hereinafter sometimes referred to as NOACK 150°C).

[0016] The following describes in detail the components contained in a lubricating oil composition according to one aspect of the present invention.

[0017] <Ingredient (A): Base Oil> In the lubricating oil composition of the present invention, the base oil (A) uses a base oil containing a fraction of hydrocarbon groups having 14 or more but less than 16 carbon atoms, ranging from 0.10% to 0.60% by mass based on the total amount of base oil (A), and a fraction containing hydrocarbon groups having 16 or more but less than 18 carbon atoms, ranging from 0.35% to 1.85% by mass based on the total amount of base oil (A). By using the above-mentioned fractions of base oil (A), the NOACK value at 150°C can be adjusted to below 5% by mass, thereby improving fuel efficiency under actual engine operating conditions. Furthermore, by using the above-mentioned fractions of base oil (A), a kinematic viscosity of 25 mmHg at 40°C can be obtained. 2 A lubricating oil composition with excellent fuel efficiency (below 0.5 liters / s).

[0018] From the perspective of satisfying the NOACK 150℃ value and improving fuel efficiency, the fraction containing hydrocarbon groups with 14 or more but less than 16 carbon atoms is preferably 0.10% by mass or more, 0.15% by mass or more, and 0.60% by mass or less.

[0019] From the viewpoint of satisfying the NOACK 150℃ value and improving fuel efficiency, the fraction containing hydrocarbon groups with 16 or more but less than 18 carbon atoms is preferably 0.35% by mass or more, 0.40% by mass or more, or 0.50% by mass or more, and on the other hand, 1.85% by mass or less, 1.80% by mass or less, 1.70% by mass or less, or 1.60% by mass or less.

[0020] The base oil (A) described above can be a substance that corresponds to the range of various fractions containing the above-described number of carbon atoms, based on the determination results of various fractions obtained by the method described in the following examples.

[0021] Furthermore, regarding the base oil (A), the base oil (A) of the present invention can be produced by, for example, combining mineral oils, synthetic oils, or mineral oils and synthetic oils as described below, while taking into account the measurement results of various fractions obtained by the methods described in the following examples, and in conjunction with the range of various fractions containing the aforementioned number of carbon atoms of hydrocarbon groups.

[0022] The lubricating oil composition of the present invention comprises a fraction containing hydrocarbon groups with 14 or more but less than 16 carbon atoms and a fraction containing hydrocarbon groups with 16 or more but less than 18 carbon atoms, obtained, for example, by mixing mineral oil and / or synthetic oil in a manner containing hydrocarbon groups with the aforementioned number of carbon atoms. Examples of mineral oils constituting this fraction include, for instance, atmospheric residue obtained by atmospheric distillation of crude oils such as alkane-based crude oils, intermediate-based crude oils, and cycloalkane-based crude oils; distillate obtained by vacuum distillation of these atmospheric residues; and refined oil obtained by subjecting the distillate to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, and hydrogen refining.

[0023] The base oil (A) used in the lubricating oil composition of one aspect of the present invention can be one of these mineral oils alone, or it can be a mixture of multiple mineral oils.

[0024] Furthermore, the base oil (A) used in one embodiment of the lubricating oil composition of the present invention can be a single synthetic oil or a mixture of multiple synthetic oils. Moreover, the base oil (A) used in one embodiment of the lubricating oil composition of the present invention can be a mixture of mineral oil and synthetic oil. Examples of synthetic oils include, for instance, α-olefins and / or their homopolymers, or α-olefin copolymers (e.g., ethylene-α-olefin copolymers with 8 to 14 carbon atoms, etc.), polyα-olefins; isoparaffins; polyalkylene glycols; polyphenyl ethers and other ether oils; polyol esters, diesters, monoesters and other ester oils; alkylbenzenes; alkylnaphthalenes; synthetic oils (GTL) obtained by isomerization of waxes produced from natural gas using the Fischer-Tropsch process or similar methods (GTL wax), and synthetic oils obtained by oligomerizing olefins produced using gas as a raw material (Ethylene to Liquid (ETL)). These synthetic oils can be manufactured from renewable resources.

[0025] Among these, the base oil used in one aspect of the present invention preferably comprises at least one of mineral oils selected from Groups 2 and 3 of the API (American Petroleum Institute) base oil category and synthetic oils.

[0026] Furthermore, the lubricating oil composition of one aspect of the present invention preferably also contains one or more base oils selected from polyalphaolefin (A1) and ester oils (A2). By containing these base oils, a lubricating oil composition that can meet the NOACK value of 150°C and improve fuel efficiency can be produced.

[0027] As for poly-α-olefins (A1), specifically, examples include the above-mentioned α-olefins and / or their homopolymers, α-olefin copolymers (such as ethylene-α-olefin copolymers and other α-olefin copolymers with 8 to 14 carbon atoms), etc.

[0028] As ester oils (A2), examples include the aforementioned polyol esters, diesters, and monoesters. More specifically, as ester oils (A1), examples include trimethylolpropane tridecanoate, 2-ethylhexyl palmitate, and bis(2-ethylhexyl) sebacate.

[0029] In one aspect of the present invention, when the base oil (A) contains one or more base oils selected from polyalphaolefin (A1) and ester oil (A2), from the viewpoint of satisfying the NOACK 150°C value and improving fuel efficiency, the content of polyalphaolefin (A1) or ester oil (A2) or a mixture thereof, based on the total amount of the lubricating oil composition (100% by mass), is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 7.0% by mass or more. In addition, from the viewpoint of suppressing the deterioration of rubber materials, it is preferably 10.0% by mass or less, more preferably 9.0% by mass or less.

[0030] In one embodiment of the present invention, the base oil (A) preferably has a kinematic viscosity of 2.5 mm at 100°C. 2 / s or more, preferably 2.8mm 2 / s or higher, preferably 3.0mm 2 / s or higher, and preferably 4.5mm 2 / s or less, more preferably 4.1mm 2 / s or less, more preferably 3.8mm 2 / s or less.

[0031] If the kinematic viscosity of the base oil at 100°C is 2.5 mm 2 A viscosity of 4.5 m / s or higher is preferred to maintain the oil film. On the other hand, if the kinematic viscosity of the base oil at 100°C is 4.5 mm... 2 A viscosity of / s or less can suppress power loss caused by viscous resistance and improve fuel efficiency, thus it is preferred. In one aspect of the present invention, when using a blended oil as the base oil (A), the kinematic viscosity of the blended oil at 100°C is preferably within the range described above.

[0032] Furthermore, from the viewpoint of suppressing viscosity changes caused by temperature variations and improving fuel efficiency, the viscosity index of the base oil used in one aspect of the present invention is preferably 80 or higher, more preferably 90 or higher, further preferably 100 or higher, and even more preferably 110 or higher.

[0033] In this specification, kinematic viscosity and viscosity index refer to values ​​measured or calculated in accordance with ASTM D455.

[0034] In one embodiment of the present invention, the content of base oil (A) in the lubricating oil composition is, based on the total amount (100% by mass) of the lubricating oil composition, 70% by mass or more, 75% by mass or more, and 99.9% by mass or less, 98% by mass or less, or 95% by mass or less.

[0035] <Ingredient (B): Viscosity index improver> One aspect of the lubricating oil composition of the present invention further comprises a viscosity index improver (B) including a comb-shaped polymer (B1). As the viscosity index improver (B), the presence of the comb-shaped polymer (B1) improves the fuel efficiency of the lubricating oil composition. The comb-shaped polymer (B1) can be any polymer having a structure with multiple tripartite branches extending from the main chain. The comb-shaped polymer (B1) used in one aspect of the present invention is preferably a polymer having at least a structural unit (X1) derived from a macromolecular monomer (x1). This structural unit (X1) conforms to the aforementioned "high molecular weight side chain".

[0036] It should be noted that in this invention, the above-mentioned "macromonomer (x1)" refers to a high molecular weight monomer with polymerizable functional groups, preferably a high molecular weight monomer with polymerizable functional groups at the end.

[0037] The comb polymer (B1) used in one aspect of the present invention may be a homopolymer consisting only of structural units (X1) derived from one type of macromonomer (x1), or a copolymer containing structural units (X1) derived from two or more types of macromonomers (x1).

[0038] In addition, the comb polymer (B1) used in one aspect of the present invention may be a copolymer comprising structural units derived from macromonomers (x1) and structural units (X2) derived from other monomers besides macromonomers (x1).

[0039] As a specific structure of such comb polymer, a copolymer having side chains comprising structural units (X1) derived from macromonomers (x1) is preferred, relative to the main chain comprising structural units (X2) derived from monomers (x2).

[0040] Examples of monomers (x2) include alkyl (meth)acrylates, vinyl monomers containing nitrogen atoms, vinyl monomers containing hydroxyl groups, monomers containing phosphorus atoms, aliphatic hydrocarbon vinyl monomers, alicyclic hydrocarbon vinyl monomers, vinyl esters, vinyl ethers, vinyl ketones, vinyl monomers containing epoxy groups, vinyl monomers containing halogen elements, esters of unsaturated polycarboxylic acids, dialkyl fumarate, dialkyl maleate, and aromatic hydrocarbon vinyl monomers.

[0041] It should be noted that in this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are converted values ​​of standard polystyrene obtained by gel permeation chromatography (GPC).

[0042] Furthermore, in one embodiment of the lubricating oil composition of the present invention, the content of the comb-shaped polymer (B1), from the viewpoint of improving fuel efficiency, is preferably 5.0% by mass or more, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. Additionally, the content of the comb-shaped polymer (B1), based on the total amount (100% by mass) of the lubricating oil composition, is preferably 14.0% by mass or less, more preferably 13.0% by mass or less, and even more preferably 12.5% ​​by mass or less.

[0043] In addition, the viscosity index improver (B) used in one aspect of the present invention may contain a viscosity index improver comprising other polymers besides the comb polymer (B1) described above, or it may not contain any, without compromising the effect of the present invention.

[0044] Other examples of such polymers include polymethyl methacrylate, dispersed polymethyl methacrylate, olefin copolymers (e.g., ethylene-propylene copolymers), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers), which are not comb-shaped polymers.

[0045] <Ingredient (C): Friction modifier> One embodiment of the lubricating oil composition of the present invention further comprises at least one friction modifier (C) selected from ashless friction modifier (C1) and molybdenum-based friction modifier (C2). By including the above-mentioned friction modifier (C), a lubricating oil composition with excellent frictional properties can be prepared. In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of further improving frictional properties, both ashless friction modifier (C1) and molybdenum-based friction modifier (C2) are included as friction modifier (C).

[0046] <Gray-free friction modifier (C1)> The ashless friction modifier (C1) used as one aspect of the present invention is not particularly limited, and examples include amine compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea compounds, hydrazide compounds, and other ashless friction modifiers (C1). One type of ashless friction modifier (C1) may be used alone or in combination of two or more.

[0047] By including an ashless friction modifier (C1), a lubricating oil composition with excellent frictional properties can be prepared. Furthermore, even if an ester oil (A2) is included as a base oil (A) in a lubricating oil composition of one aspect of the present invention, the frictional properties can be well maintained by blending an ashless friction modifier (C1) with a specific weight-average molecular weight (Mw), thereby maintaining good fuel-saving performance.

[0048] In one aspect of the present invention, from the viewpoint of improving frictional properties, 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 1,000, 1,000 or more and less than 10,000, or 10,000 or more and less than 50,000, more preferably 1,000 or more and less than 50,000.

[0049] In one aspect of the present invention, from the viewpoint of producing a lubricating oil composition having excellent frictional properties, the total content of the ashless friction modifier (C1) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, it can be 1.0% by mass or less, 0.8% by mass or less, or 0.5% by mass or less.

[0050] <Molybdenum-based friction modifier (C2)> As one embodiment of the present invention, the molybdenum-based friction modifier (C2) may include molybdenum compounds such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid. One type of molybdenum-based friction modifier (C2) may be used alone or in combination of two or more types.

[0051] Among these, in one embodiment of the present invention, the lubricating oil composition preferably contains molybdenum dithiocarbamate (MoDTC) as a molybdenum-based friction modifier (C2).

[0052] <<Molybdenum dithiocarbamate (MoDTC)>> As one aspect of the present invention, molybdenum dithiocarbamate (MoDTC) can be exemplified by compounds of the following general formula (1).

[0053] [Chemistry 1] In equation (1), R 1 ~R 4 Each group is independently a hydrocarbon group with 4 to 18 carbon atoms, preferably an alkyl group with 5 to 18 carbon atoms, an alkenyl group with 5 to 18 carbon atoms, a cycloalkyl group with 5 to 18 carbon atoms, an aryl group with 6 to 18 carbon atoms, an alkylaryl group with 7 to 18 carbon atoms, or an arylalkyl group with 7 to 18 carbon atoms.

[0054] Examples of alkyl groups with 5 to 18 carbon atoms include pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, and octadecyl.

[0055] Examples of alkenyl groups with 5 to 18 carbon atoms include octenyl, nonenyl, decenyl, undecenyl, dodecaenyl, tridecenyl, tetradecenyl, and pentadecenyl.

[0056] Examples of cycloalkyl groups with 5 to 18 carbon atoms include cyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, methylcyclohexylmethyl, cyclohexylethyl, propylcyclohexyl, butylcyclohexyl, and heptylcyclohexyl.

[0057] Examples of aryl groups with 6 to 18 carbon atoms include phenyl, naphthyl, anthracene, biphenyl, and terphenyl.

[0058] Examples of alkylaryl groups with 7 to 18 carbon atoms include tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, and dimethylnaphthyl.

[0059] Examples of arylalkyl groups with 7 to 18 carbon atoms include phenylmethyl, phenylethyl, and diphenylmethyl.

[0060] In one aspect of the present invention, from the viewpoint of producing a lubricating oil composition having excellent frictional properties, the content of molybdenum dithiocarbamate (MoDTC), based on the total amount (100% by mass) of the lubricating oil composition, is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.6% by mass or more. Alternatively, it can be 1.0% by mass or less, 0.9% by mass or less, or 0.8% by mass or less.

[0061] <Various Additives> In one embodiment of the present invention, the lubricating oil composition may contain various additives as needed, without impairing the effects of the present invention.

[0062] Such additives include, for example, pour point depressants, antioxidants, metal detergents, ashless dispersants, wear-resistant agents, rust inhibitors, defoamers, and extreme pressure additives.

[0063] These lubricant additives can be used individually or in combination of two or more.

[0064] The content of each of these various additives can be appropriately adjusted within the range without impairing the effect of the present invention. Based on the total amount (100% by mass) of the lubricating oil composition, each additive is typically 0.001 to 15% by mass, preferably 0.005 to 10% by mass, and more preferably 0.01 to 5% by mass.

[0065] Alternatively, compounds that have multiple functions as the aforementioned additives can be used (e.g., compounds that function as wear-resistant agents and extreme pressure additives).

[0066] [Pour point depressant] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressant may be used alone or in combination of two or more types.

[0067] Examples of pour point depressants used as one aspect of the present invention include, for example, ethylene-vinyl acetate copolymers, condensates of chlorinated alkanes and naphthalene, condensates of chlorinated alkanes and phenol, polymethyl methacrylate, and polyalkyl styrene.

[0068] [Antioxidants] The lubricating oil composition of one aspect of the present invention may further contain an antioxidant. The antioxidant may be used alone or in combination of two or more.

[0069] Examples of antioxidants used in one aspect of this invention include amine antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; phenolic antioxidants such as 2,6-di-tert-butylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; and sulfur-based antioxidants such as phenothiazine, dioctadecyl sulfide, dilauryl 3,3'-thiodipropionate, and 2-mercaptobenzimidazole.

[0070] [Metallic-based detergent] One embodiment of the lubricating oil composition of the present invention may further contain a metallic detergent. The metallic detergent may be used alone or in combination of two or more.

[0071] As a metal-based detergent used in one aspect of the present invention, examples include metal salts such as metal sulfonates, metal salicylates, and metal phenolates. Furthermore, the metal atoms constituting the metal salt are preferably selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium or magnesium.

[0072] [Ash-free dispersant] The lubricating oil composition of one embodiment of the present invention may further contain an ashless dispersant. The ashless dispersant may be used alone or in combination of two or more.

[0073] As an ashless dispersant used in one aspect of the present invention, an alkenyl succinimide is preferably used, which can be a modified alkenyl succinic animide formed by reacting with one or more selected from boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds and organic acids.

[0074] [Abrasion-resistant agent] The lubricating oil composition of one aspect of the present invention may further contain a wear-resistant agent. The wear-resistant agent may be used alone or in combination of two or more types.

[0075] As a wear-resistant agent used in one aspect of the present invention, examples include sulfur-containing compounds such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfide compounds, sulfurized olefins, sulfurized oils, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfide compounds; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and their amine or metal salts; and wear-resistant agents containing sulfur and phosphorus such as thiophosphites, thiophosphates, thiophosphonates, and their amine or metal salts.

[0076] Rust Inhibitor The lubricating oil composition of one aspect of the present invention may further contain a rust inhibitor. The rust inhibitor may be used alone or in combination of two or more.

[0077] Examples of rust inhibitors used as one aspect of the present invention include, for example, fatty acids, alkenyl succinate half-esters, fatty acid soaps, alkyl sulfonates, polyol fatty acid esters, fatty acid amines, oxidized alkanes, alkyl polyoxyethylene ethers, etc.

[0078] [Defoamer] The lubricating oil composition of one aspect of the present invention may further contain an antifoaming agent. The antifoaming agent may be used alone or in combination of two or more.

[0079] Examples of defoamers used as one aspect of this invention include alkyl silicone defoamers, fluorosilicone defoamers, and fluoroalkyl ether defoamers.

[0080] [Extreme Pressure Additive] The lubricating oil composition of one embodiment of the present invention may further contain extreme pressure additives. Extreme pressure additives may be used alone or in combination of two or more.

[0081] Extreme pressure additives used in one aspect of the present invention include, for example, sulfur-containing compounds such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfide compounds, sulfurized olefins, sulfurized oils, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfide compounds; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and their amine or metal salts; and wear-resistant agents containing sulfur and phosphorus such as thiophosphites, thiophosphates, thiophosphonates, and their amine or metal salts.

[0082] [Method for manufacturing lubricating oil composition] The method for manufacturing the lubricating oil composition, as one aspect of the present invention, is not particularly limited, but is preferably a method that includes the step of blending various other additives into the base oil (A) as needed. The blending order of the components can be appropriately set.

[0083] [Properties of the lubricating oil composition] The kinematic viscosity of the lubricating oil composition of one embodiment of the present invention is preferably 5.0 mm at 100°C. 2 / s or higher, more preferably 5.5mm 2 / s or higher, more preferably 6.1mm 2 / s or higher, and preferably 12.5mm. 2 / s or less, more preferably 10.0mm 2 / s or less, more preferably 9.3mm 2 / s or less.

[0084] The NOACK value of the lubricating oil composition of one aspect of the present invention, measured according to ASTM D5800 at 150°C for 12 hours, is preferably 5% by mass or less, with no particular limitation on the lower limit, for example, 3% by mass or more.

[0085] Using a lubricating oil composition according to one aspect of the present invention as a sample oil, the coefficient of friction measured by the method described in the following examples is preferably 0.110 or less, more preferably 0.106 or less, further preferably less than 0.085, and even more preferably 0.084 or less. It can be said that lubricating oil compositions with a coefficient of friction within the above-mentioned range have excellent frictional properties.

[0086] [Uses of Lubricating Oil Compositions] The lubricating oil composition of the present invention has low oil evaporation, as indicated by the NOACK value at 150°C, and is therefore suitable for use in the lubrication of internal combustion engines.

[0087] Therefore, the present invention also provides the internal combustion engine described in [I] below and the method of using the lubricating oil composition described in [II] below.

[0088] [I] An internal combustion engine filled with a lubricating oil composition according to one aspect of the present invention.

[0089] [II] A method of using a lubricating oil composition, wherein the lubricating oil composition of one aspect of the present invention described above is applied to the lubrication of an internal combustion engine.

[0090] The present invention includes the following methods.

[0091] [1] A lubricating oil composition, wherein, as a base oil (A), it comprises: a fraction containing hydrocarbon groups having 14 or more carbon atoms and less than 16 carbon atoms in a range of 0.10 to 0.60% by mass based on the total amount of base oil (A), and a fraction containing hydrocarbon groups having 16 or more carbon atoms and less than 18 carbon atoms in a range of 0.35 to 1.85% by mass based on the total amount of base oil (A).

[0092] [2] The lubricating oil composition according to [1] contains an ashless friction modifier (C1) having a weight-average molecular weight (Mw) of 100 or more and less than 50,000.

[0093] [3] The lubricating oil composition according to [1] contains an ashless friction modifier (C1) having a weight-average molecular weight (Mw) of 1,000 or more and less than 50,000.

[0094] [4] The lubricating oil composition according to any one of [1] to [3], wherein, as base oil (A), it further comprises one or more base oils selected from polyalphaolefin (A1) and ester oil (A2).

[0095] [5] The lubricating oil composition according to [4], wherein, as the base oil (A), it comprises an ester oil (A2).

[0096] [6] The lubricating oil composition according to any one of [1] to [5] further comprises: a viscosity index improver (B) containing a comb polymer (B1).

[0097] [7] The lubricating oil composition according to any one of [1] to [6] further comprises a molybdenum-based friction modifier (C2). Example

[0098] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. It should be noted that the various physical property values of the respective components used in the examples and comparative examples and the obtained lubricating oil compositions were measured according to the following methods.

[0099] (1) Kinematic viscosity and viscosity index Measured and calculated according to ASTM D455. A kinematic viscosity at 40 °C of 25 mm 2 / s or less was judged as qualified.

[0100] (2) Weight-average molecular weight (Mw), number-average molecular weight (Mn) In a "1515 Isocratic HPLC pump" and a "2414 differential refractive index (RI) detector" manufactured by Waters Corporation, one column "TSKguardcolumn SuperHZ-L" and two columns "TSKSuperMultipore HZ-M" manufactured by Tosoh Corporation were installed in order from the upstream side. The measurement was carried out 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 calculated according to standard polystyrene conversion.

[0101] (3) Fraction amount of hydrocarbon groups having 14 or more and less than 16 carbon atoms and 16 or more and less than 18 carbon atoms Using the following measuring device and under the following measuring conditions, within the range of 8 or more and less than 10 carbon atoms, 10 or more and less than 12 carbon atoms, and then the carbon atoms increasing by 2 each time, and 36 or more and less than 38 carbon atoms, calculate the peak area of the fraction of hydrocarbon groups having each carbon atom number, and calculate the ratio of the fraction of hydrocarbon groups having 14 or more and less than 16 carbon atoms to the total peak area, and the ratio of the fraction of hydrocarbon groups having 16 or more and less than 18 carbon atoms to the total peak area, respectively.

[0102] (Measuring device) Device: GC-2014 manufactured by Shimadzu Corporation Type of detector: FID Column: Packed column Packing agent: Silicone OV-1 1.5%・Shinwasorb-S 60 / 80 (Measuring conditions) Syringe temperature: 360 °C Detector temperature: 360 °C Temperature rising condition: Initial temperature 60 °C Temperature rising rate: 10 °C / min Final temperature of temperature rising: 350 °C Final temperature hold time: 5 min Gas flow rate: N 245 mL / min (4) NOACK 150℃ According to ASTM D5800, the test is conducted at 150°C for 12 hours. A NOACK value of less than 5% by mass at 150°C is considered acceptable.

[0103] (5) Coefficient of friction [Evaluation of the coefficient of friction] The coefficient of friction of the prepared lubricating oil composition was determined using an SRV testing machine (manufactured by Optimol) under the following conditions.

[0104] First, the experiment was conducted by increasing the temperature by 10°C each time from 30°C to 140°C, while sliding the temperature under the following conditions for 5 minutes at each temperature.

[0105] In the final minute of the test at 30°C, the coefficient of friction was measured every second, and the average value of the coefficient of friction in the final minute was calculated.

[0106] • Cylinder: AISI52100 • Mirror finish: AISI 52100 (Maximum height roughness (Rz): less than 0.20 μm) • Vibration frequency: 50Hz • Amplitude: 1.5mm • Load: 400N • Temperature: 30~140℃, increasing by 10℃ each time • Test duration: 5 minutes at each temperature The coefficient of friction was evaluated as follows: the coefficient of friction measured at 30°C using the sample oil of Example 1 was used as a benchmark, and the improvement rate calculated using the following formula was used as the evaluation index. It should be noted that "-" in Tables 1-2 indicates that the coefficient of friction was not measured.

[0107] Formula: Improvement rate = 100 - (Friction coefficient of each example at 30°C / Friction coefficient of Example 1 at 30°C × 100) Examples 1-18, Comparative Examples 1-4 The various components and other additives shown in Tables 1 and 2 were added and mixed at the proportions shown in Tables 1 and 2 to prepare lubricating oil compositions. It should be noted that the proportions of viscosity index improvers in Tables 1 and 2 include the amount of diluent oil. Details of the components used to prepare the lubricating oil compositions are shown below.

[0108] <Ingredient (A): Base Oil> • Base oil (A): Base oils adjusted using base oils (1) to (22) listed in Tables 1 to 2, with the fraction having 14 or more but less than 16 carbon atoms and the fraction having 16 or more but less than 18 carbon atoms respectively having the values ​​listed in Tables 1 to 2. The kinematic viscosity of base oils (1) to (22) at 100°C is 2.61 to 4.45 mm. 2 / s, viscosity index in the range of 111~164.

[0109] <Ingredient (B): Viscosity index improver> • Comb polymer (B1): A comb polymer with a structure having multiple trifurcation points with high molecular weight side chains emerging from the main chain (Mw=260,000, Mw / Mn=3.1, resin content=23%). <Ingredient (C): Friction modifier> • Ashless friction modifier (C1) (1): Stearyl diethanolamine (Mw=350, N content=4.2 wt%, resin content=99%) • Ash-free friction modifier (C1) (2) Polymethyl methacrylate (Mw=9800, N content=0.25% by weight, resin composition=78%).

[0110] • Ashless friction modifier (C1) (3): Polymethyl methacrylate (Mw=18000, N content=0.24% by weight, resin composition=67%).

[0111] • Ash-free friction modifier (C1) (4): Polymethyl methacrylate (Mw=57000, N content=0.40% by weight, resin content=33.2%) • Molybdenum-based friction modifier (C2): molybdenum dithiocarbamate (MoDTC) (R in formula (1) 1 ~R 4 Each is independently an 8 or 13 hydrocarbon group, X 1 ~X 4 This is a compound containing oxygen atoms. The molybdenum atom content is 10.0% by mass, and the sulfur atom content is 11.5% by mass.

[0112] <Other Additives> • An additive mixture consisting of detergents, dispersants, ZnDTP, antioxidants, metal inerts, defoamers, and friction modifiers.

[0113] [Table 1]

[0114] [Table 2]

[0115] Based on the results in Tables 1-2, the lubricating oil compositions of Examples 1-18, which contain, as base oil (A), a fraction containing hydrocarbon groups with 14 or more but less than 16 carbon atoms at a mass percentage of 0.10-0.60% (based on the total amount of base oil (A)) and a fraction containing hydrocarbon groups with 16 or more but less than 18 carbon atoms at a mass percentage of 0.35-1.85% (based on the total amount of base oil (A)), have a NOACK value of 5% (based on the mass percentage) or less at 150°C, indicating low oil evaporation. Furthermore, the kinematic viscosity of the lubricating oil compositions of Examples 1-18 at 40°C is 25 mm. 2 The oil composition exhibits excellent fuel efficiency (at a speed of less than 1 / s). On the other hand, the lubricating oil compositions of Comparative Examples 1 to 4 do not meet the acceptable standards for NOACK value at 150°C or kinematic viscosity at 40°C.

Claims

1. A lubricating oil composition, wherein, As the base oil (A), a base oil containing a fraction containing a hydrocarbon group having 14 or more and less than 16 carbon atoms in a range of 0.10 to 0.60% by mass based on the total amount of the base oil (A), and a fraction containing a hydrocarbon group having 16 or more and less than 18 carbon atoms in a range of 0.35 to 1.85% by 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 (Cl), the weight average molecular weight (Mw) of the ashless friction modifier (Cl) being 100 or more and less than 50,000.

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

4. The lubricating oil composition of any of claims 1-3, wherein, As the base oil (A), one or more kinds of base oils selected from the group consisting of poly-alpha-olefins (Al) and ester-based oils (A2) are further included.

5. The lubricating oil composition of claim 4, wherein, As the base oil (A), an ester-based oil (A2) is included.

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 (Bl).

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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