Lubricant composition

Abstract

To provide a lubricant composition capable of suppressing metal corrosion on engine parts even when a fuel containing biofuel is used in an internal combustion engine.SOLUTION: A lubricant composition for use in an internal combustion engine using a fuel containing biofuel, comprises: (A) a base oil; (B) a non-boronated bis-imide dispersant; (C) an alkali metal borate; and (D) a primary zinc dialkyldithiophosphate, wherein the content of the non-boronated bis-imide dispersant (B) is 3.00 mass% or more based on the total amount of the lubricant composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to lubricating oil compositions for use in internal combustion engines using fuels including biofuels. [Background technology]

[0002] At present, environmental regulations are becoming increasingly strict on a global scale, and especially the situation surrounding automobiles is becoming increasingly strict in terms of fuel efficiency and exhaust gas regulations. Behind this lies environmental issues such as global warming, and the need to protect resources due to concerns about the depletion of petroleum resources. In response to the above problems, so-called biofuels, which are made from biological resources (biomass) such as plants, have been attracting attention in recent years as an alternative to fossil fuels such as petroleum. It is said that the carbon dioxide generated by burning biofuels is offset by the carbon dioxide absorbed by the plants that are the raw materials for the fuel during their growth. Therefore, it is expected that the use of biofuels will become more widespread in the future in order to reduce carbon dioxide emissions, which are the main cause of global warming. In preparation for the widespread use of biofuels, attempts have been made to improve lubricating oil compositions for use in automobile internal combustion engines in accordance with the characteristics of biofuels that differ from those of conventionally used petroleum, etc. For example, Patent Document 1 discloses a lubricating oil composition that contains a phenolic antioxidant and an amine antioxidant in combination, thereby effectively suppressing deterioration of the lubricating oil, particularly deterioration of cleaning performance, even when biodiesel fuel is mixed into the fuel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-024123 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, in internal combustion engines, especially diesel engines, particulate matter (PM; soot) and NOX Environmental pollution caused by exhaust gas components such as these is a problem. For this reason, automobiles equipped with diesel engines are equipped with exhaust gas purification devices such as diesel particulate filters (DPFs) and exhaust gas purification catalysts (oxidation or reduction catalysts). Generally, when a diesel engine is equipped with a DPF, post-injection of fuel is performed to burn the soot accumulated in the filter. This post-injection increases fuel dilution in the engine oil, which is expected to reduce engine oil performance. Here, when the above-mentioned biofuel is used as fuel, the biofuel easily accumulates in the engine oil due to its physical properties. In addition, polar compounds are produced when the biofuel decomposes. These factors are thought to have a significant adverse effect on corrosion of metal engine parts such as pistons. However, improvements in lubricating oil compositions with respect to inhibiting metal corrosion of engine parts caused by the contamination of biofuels are not sufficient, and further improvements in performance are required.

[0005] An object of the present invention is to provide a lubricating oil composition that can suppress metal corrosion of engine parts even when a fuel containing a biofuel is used in an internal combustion engine. [Means for solving the problem]

[0006] The present inventors have conducted extensive research in order to solve the above problems. As a result, it has been discovered that when a lubricating oil composition contains a certain amount of a non-boronated bisimide dispersant (B), and further contains an alkali metal borate (C) and a zinc primary dialkyldithiophosphate (D), it is possible to inhibit metal corrosion of engine parts in an internal combustion engine, even when fuels containing biofuels are used. Based on the above findings, the present inventors further conducted various studies and completed the present invention.

[0007] According to the present invention, the following [1] to [3] are provided. [1] A lubricating oil composition for use in an internal combustion engine using a fuel containing a biofuel, A lubricant composition comprising: a base oil (A); a non-boronated bisimide dispersant (B); an alkali metal borate (C); and a primary zinc dialkyldithiophosphate (D); A lubricating oil composition, wherein the content of the non-boronated bisimide dispersant (B) is 3.00 mass% or more based on the total amount of the lubricating oil composition. [2] A method for producing a lubricating oil composition for use in an internal combustion engine using a fuel containing a biofuel, comprising the steps of: The method includes the steps of: mixing a base oil (A), a non-boronated bisimide dispersant (B), an alkali metal borate (C), and a primary zinc dialkyldithiophosphate (D); In the above step, the non-boronated bisimide dispersant (B) is blended in an amount of 3.00 mass% or more based on the total amount of the lubricating oil composition. [3] A method for lubricating an internal combustion engine using a fuel containing a biofuel, comprising using the lubricating oil composition according to [1]. Effect of the Invention

[0008] According to the present invention, it is possible to provide a lubricating oil composition that is capable of suppressing metal corrosion of engine parts even when a fuel containing a biofuel is used in an internal combustion engine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The upper and lower limit values ​​of the numerical ranges described in this specification can be combined in any combination. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges "A to D" and "C to B" are also included in the scope of the present invention. In addition, unless otherwise specified, a numerical range of "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value. In this specification, the numerical values ​​in the examples are numerical values ​​that can be used as upper or lower limits.

[0010] [Embodiments of the lubricating oil composition] The lubricating oil composition of the present embodiment contains a base oil (A), a non-boronated bisimide dispersant (B), an alkali metal borate (C), and a primary zinc dialkyldithiophosphate (D), and the content of the non-boronated bisimide dispersant (B) is 3.00 mass% or more based on the total amount of the lubricating oil composition.

[0011] In the following description, the “base oil (A)”, the “non-boronated bisimide dispersant (B)”, the “alkali metal borate (C)”, and the “zinc primary dialkyldithiophosphate (D)” will also be referred to as “component (A)”, “component (B)”, “component (C)”, and “component (D)”, respectively.

[0012] The lubricating oil composition of the present embodiment may be composed only of component (A), component (B), component (C), and component (D), or may further contain components other than component (A), component (B), component (C), and component (D). In the lubricating oil composition of this embodiment, the total content of components (A), (B), (C) and (D) is, based on the total amount of the lubricating oil composition, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, still more preferably 80 mass% or more, even more preferably 85 mass% or more, and even more preferably 88 mass% or more.

[0013] Each component contained in the lubricating oil composition of this embodiment, and the biofuel used in internal combustion engines will be described in detail below.

[0014] <Biofuel> The biofuel used in the present embodiment is not particularly limited, and may include fuels containing one or more selected from the group consisting of natural fats and oils, hydrogenated products of natural fats and oils, transesterified products of natural fats and oils, and hydrogenated products of transesterified products of natural fats and oils. Note that the natural fats and oils in the present embodiment are not limited to those of plant origin, and may also include those of animal origin.

[0015] As natural fats and oils, various animal and vegetable fats that are widely present in nature can be used, including vegetable oils whose main component is an ester of fatty acid and glycerin, such as safflower oil, soybean oil, rapeseed oil, palm oil, palm kernel oil, cottonseed oil, coconut oil, rice bran oil, sesame oil, castor oil, linseed oil, olive oil, tung oil, camellia oil, peanut oil, kapok oil, cacao oil, Japan wax, sunflower oil, and corn oil. The hydrogenated products of natural fats and oils are those obtained by subjecting the above-mentioned fats and oils to so-called hydrogenation in the presence of a suitable hydrogenation catalyst. Examples of the hydrogenation catalyst include nickel-based catalysts and platinum group (Pt, Pd, Rh, Ru)-based catalysts, etc. Two or more of the above catalysts may be used in combination as the hydrogenation catalyst.

[0016] The transesterification product of natural fats and oils is an ester obtained by transesterification of triglycerides constituting natural fats and oils in the presence of a suitable ester synthesis catalyst. For example, fatty acid esters that can be used as biofuels are produced by transesterifying lower alcohols and fats and oils in the presence of the ester synthesis catalyst. The lower alcohol is used as an esterification agent, and examples of alcohols having 5 or less carbon atoms include methanol, ethanol, propanol, butanol, and pentanol, among which methanol is selected in terms of reactivity and cost. Such lower alcohols are generally used in an amount equivalent to or greater than the amount of fats and oils. The hydrogenated product of the transesterification of natural fats and oils is obtained by hydrogenating the above-mentioned transesterification product in the presence of a suitable hydrogenation catalyst. Natural fats and oils, hydrotreated natural fats and oils, transesterified natural fats and oils, and hydrotreated transesterified natural fats and oils can also be used as blended fuels by adding them to fuels composed of hydrocarbons such as diesel. When used as a mixed fuel, it can be suitably used in fuels such as B5, which is a fuel composed of hydrocarbons such as diesel and 5% biofuel mixed together, B30, which is a fuel composed of hydrocarbons such as diesel and 30% biofuel mixed together, and B40, which is a fuel composed of hydrocarbons such as diesel and 40% biofuel mixed together. Furthermore, it naturally does not contain any hydrocarbons such as diesel, and can be suitably used for B100 fuel, which is composed only of biofuel.

[0017] <Base oil (A)> The lubricating oil composition of the present embodiment contains a base oil (A). As the base oil (A), one or more oils selected from the group consisting of mineral oils and synthetic oils that have conventionally been used as base oils for lubricating oil compositions can be used without any particular limitation.

[0018] Examples of mineral oils include atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate base crude oil, or naphthenic crude oil; distillate oils obtained by vacuum distillation of these atmospheric residual oils; and mineral oils obtained by subjecting the distillate oils to one or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0019] As the synthetic oil, synthetic oils that have been used as base oils for lubricating oil compositions can be used without any particular restrictions. For example, polyolefins such as polybutene, 1-octene oligomer, 1-decene oligomer, and hydrogenated products thereof, ethylene-α-olefin copolymers, isoparaffin, various esters such as polyol esters and dibasic acid esters, various ethers such as polyphenyl ether, polyalkylene glycols, alkylbenzenes, alkylnaphthalenes, and GTL base oils obtained by isomerizing wax (gas-to-liquid (GTL) wax) produced from natural gas by the Fischer-Tropsch process, etc.

[0020] The mineral oils may be used alone or in combination of two or more. The synthetic oils may be used alone or in combination of two or more. Also, one or more mineral oils may be used in combination with one or more synthetic oils.

[0021] The kinematic viscosity of the base oil (A) is not particularly limited, but it is preferable that it is within the following range. The base oil (A) preferably has a kinetic viscosity at 40° C. (hereinafter also referred to as “40° C. kinetic viscosity”) of 13.5 mm 2 / s~506mm 2 / s, more preferably 28.8 mm 2 / s~352mm 2 / s, and more preferably 41.4 mm 2 / s~242mm 2 / s. The base oil (A) preferably has a kinetic viscosity at 100° C. (hereinafter also referred to as “100° C. kinetic viscosity”) of 4.0 mm 2 / s or more 26.1mm 2 / s, preferably less than 5.0 mm 2 / s or more 21.9mm 2 / s, more preferably less than 6.1 mm 2 / s or more 16.3mm 2 / s. In this specification, the 40° C. kinematic viscosity and 100° C. kinematic viscosity of the base oil (A) refer to values ​​measured in accordance with JIS K2283:2000. When the base oil (A) is a mixed base oil containing two or more kinds of base oils, the 40° C. kinematic viscosity and 100° C. kinematic viscosity of the mixed base oil are preferably within the above ranges.

[0022] In this embodiment, the content of the base oil (A) in the lubricating oil composition is preferably 60.00 mass% or more, more preferably 70.00 mass% or more, even more preferably 80.00 mass% or more, based on the total amount of the lubricating oil composition, and is preferably 95.00 mass% or less, more preferably 92.00 mass% or less, even more preferably 90.00 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the content is preferably 60.00 mass % to 95.00 mass %, more preferably 70.00 mass % to 92.00 mass %, and even more preferably 80.00 mass % to 90.00 mass %.

[0023] <Non-boronated bisimide dispersants (B)> The lubricating oil composition of this embodiment contains 3.00 mass% or more of the non-boronated bisimide dispersant (B) based on the total amount of the lubricating oil composition. The lubricating oil composition contains the non-boronated bisimide dispersant (B) in the above range, and also contains the alkali metal borate (C) and the primary zinc dialkyldithiophosphate (D), so that the metal corrosion inhibition of engine parts can be improved. The reason for this is unclear, but it is presumed that, for example, by containing the non-boronated bisimide dispersant (B) in the above range, polar compounds that are generated by the degradation and decomposition of biofuel, which cause metal corrosion, can be inactivated.

[0024] Specifically, the non-boronated bisimide dispersant (B) is preferably one or more compounds selected from the group consisting of non-boronated alkenyl succinic acid bisimides and non-boronated alkyl succinic acid bisimides.

[0025] Examples of the non-boronated alkenyl succinic acid bisimide and the non-boronated alkyl succinic acid bisimide include compounds represented by the following general formula (b1).

[0026] [ka]

[0027] In the above general formula (b1), R B1 and R B5 are each independently an alkenyl group or an alkyl group; R B2 and R B4 are each independently an alkylene group having 1 to 6 carbon atoms; R B3is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a group represented by -(A1O)xH (wherein A1 is an alkylene group having 2 to 4 carbon atoms, and x is an integer of 1 to 10), and n1 is an integer of 0 to 20. When n1 is 2 or more, multiple R B2 and R B3 may be the same or different.

[0028] The mass average molecular weight (Mw) of the compound represented by the above general formula (b1) is preferably 1,000 to 60,000, more preferably 3,000 to 50,000, and even more preferably 4,000 to 48,000, from the viewpoints of improving the solubility in the base oil (A) and making it easier to improve the effects of the present invention.

[0029] In the present invention, the mass average molecular weight (Mw) of the compound represented by the above general formula (b1) can be evaluated as the mass average molecular weight (Mw) in terms of standard polystyrene, for example, by measuring under the conditions of a GPC apparatus (apparatus name: 260Infinity, manufactured by Agilent Technologies) equipped with columns (product name: LF-404 x 2, manufactured by Shodex Co., Ltd.), a detector: a refractive index detector, a measurement temperature: 35°C, a mobile phase: chloroform, a flow rate: 0.3 mL / min, and a concentration of 0.2 wt%.

[0030] R B1 and R B5 Examples of the alkenyl group that can be selected as the alkyl group include a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer, and examples of the alkyl group include hydrogenated versions of these groups. The polybutenyl group is preferably a mixture of 1-butene and isobutene, or a polymer of high-purity isobutene. Among these, the alkenyl group is preferably a polybutenyl group or a polyisobutenyl group, and examples of the alkyl group include a hydrogenated polybutenyl group or a polyisobutenyl group. In the lubricating oil composition of the present embodiment, from the viewpoint of making it easier to improve the effects of the present invention, B1 and R B5The group that can be selected as is preferably an alkenyl group, and among alkenyl groups, a polybutenyl group is more preferable.

[0031] R B2 and R B4 As alkylene groups having 1 to 6 carbon atoms that can be selected from the viewpoints of improving the solubility in the base oil (A) and facilitating the improvement of the effects of the present invention, preferred are methylene groups, various ethylene groups such as 1,1-ethylene and 1,2-ethylene groups, various propylene groups such as 1,3-propylene, 1,2-propylene, and 2,2-propylene, various butylene groups, various pentylene groups, and various hexylene groups. In this specification, the term "various" in the various butylene groups and the like refers to linear and branched groups that are structural isomers thereof. From a similar perspective, R B2 and R B4 The alkylene group that can be selected for preferably has 2 to 5 carbon atoms, more preferably 2 to 4 carbon atoms, and even more preferably 2 or 3 carbon atoms.

[0032] R B3 Examples of the alkyl group that can be selected as the aryl group include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 1,1-dimethylhexyl group, a 2-ethylhexyl group, a nonyl group, a 1,1-dimethylheptyl group, and a decyl group. Examples of the alkylene group having 2 to 4 carbon atoms represented by A1 include an ethylene group, a trimethylene group, and various butylene groups, with an ethylene group being preferred. x is preferably an integer of 1 to 5, and more preferably an integer of 1 to 3.

[0033] In the above general formula (b1), n1 is preferably 1 to 15, more preferably 2 to 10, even more preferably 2 to 5, and even more preferably 3 or 4, from the viewpoint of improving the solubility of the component (B) represented by the above general formula (b1) in the base oil (A) and making it easier to improve the effects of the present invention.

[0034] Alkenylsuccinic acid bisimides or alkylsuccinic acid bisimides can be produced by reacting an alkenylsuccinic anhydride obtained by reacting a polyolefin with maleic anhydride, or an alkylsuccinic anhydride obtained by hydrogenating the alkenylsuccinic anhydride, with a polyamine. As the olefin monomer forming the polyolefin, one or more types selected from α-olefins having 2 to 8 carbon atoms can be mixed and used, and a mixture of isobutene and 1-butene can be preferably used. On the other hand, examples of polyamines include diamines such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine, and polyalkylenepolyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine, dibutylenetriamine, tributylenetetramine, and pentapentylenehexamine.

[0035] In this embodiment, the content of the non-boronated bisimide dispersant (B) is preferably 3.00 mass% or more, more preferably 3.50 mass% or more, even more preferably 4.00 mass% or more, and even more preferably 5.50 mass% or more, based on the total amount of the lubricating oil composition, and is preferably 12.00 mass% or less, more preferably 10.00 mass% or less, even more preferably 8.50 mass% or less, and even more preferably 7.00 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the content is preferably 3.00 mass% to 12.00 mass%, more preferably 3.50 mass% to 10.00 mass%, even more preferably 4.00 mass% to 8.50 mass%, and still more preferably 5.50 mass% to 7.00 mass%.

[0036] <Other dispersants (B')> From the viewpoint of improving detergency, the lubricating oil composition of the present embodiment may contain, in addition to the non-boronated bisimide dispersant (B), another dispersant (B') other than a compound corresponding to the non-boronated bisimide dispersant (B). As the other dispersant (B'), an imide dispersant other than the compound corresponding to the non-boronated bisimide dispersant (B) is preferable, and a boronated imide dispersant (B'2) is more preferable. The other dispersing agents (B') may be used alone or in combination of two or more.

[0037] <Boronated imide dispersant (B'2)> Specifically, the boronated imide dispersant (B'2) is preferably one or more compounds selected from the group consisting of boronated alkenyl succinic acid bisimides, boronated alkyl succinic acid bisimides, boronated alkenyl succinic acid monoimides, and boronated alkyl succinic acid monoimides. The boronated alkenyl succinimide or the boronated alkyl succinimide can be produced, for example, by reacting the alkenyl succinic anhydride or the alkyl succinic anhydride obtained by the reaction of the above-mentioned polyolefin with maleic anhydride with the above-mentioned polyamine and boron compound. Examples of the boron compound include boron oxide, boron halides, boric acid, boric anhydride, boric acid esters, and ammonium salts of boric acid.

[0038] The mass average molecular weight (Mw) of the boronated imide dispersant (B'2) is preferably from 1,000 to 60,000, more preferably from 3,000 to 50,000, and even more preferably from 4,000 to 50,000.

[0039] In the lubricating oil composition of this embodiment, the ratio of boron atoms to nitrogen atoms (B / N ratio) constituting the boronated imide dispersant (B'2) is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.6 or more, still more preferably 0.8 or more, and particularly preferably 0.9 or more.

[0040] In this embodiment, the content of the boronized imide dispersant (B'2) is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.10 mass% or more, and even more preferably 0.20 mass% or more, based on the total amount of the lubricating oil composition. Also, it is preferably 1.50 mass% or less, more preferably 1.00 mass% or less, even more preferably 0.70 mass% or less, and even more preferably 0.30 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 0.01 mass% to 1.50 mass%, more preferably 0.05 mass% to 1.00 mass%, even more preferably 0.10 mass% to 0.70 mass%, and still more preferably 0.20 mass% to 0.30 mass%.

[0041] <Non-boronated monoimide dispersant (B'1)> Examples of dispersants (B') other than the boronated imide dispersant (B'2) include non-boronated monoimide dispersants (B'1). Specific examples of the non-boronated monoimide dispersant (B'1) include one or more compounds selected from the group consisting of non-boronated alkenyl succinic acid monoimides and non-boronated alkyl succinic acid monoimides.

[0042] Examples of the non-boronated alkenyl succinic acid monoimide and the non-boronated alkyl succinic acid monoimide include compounds represented by the following general formula (b2).

[0043] [ka]

[0044] In the above general formula (b2), R B6 is an alkenyl group or an alkyl group, R B7 is an alkylene group having 1 to 6 carbon atoms, R B8is an alkyl group having 1 to 10 carbon atoms or a group represented by -(AO)H (wherein A is an alkylene group having 2 to 4 carbon atoms, and y is an integer of 1 to 10), and n is an integer of 1 to 20. When n is 2 or more, multiple R B7 and R B8 may be the same or different.

[0045] The mass average molecular weight (Mw) of the compound represented by the above general formula (b2) is, for example, 1,000 to 60,000, or 3,000 to 50,000, or 4,000 to 48,000.

[0046] In the present invention, the mass average molecular weight (Mw) of the compound represented by the above general formula (b2) can be determined by the method described in the above section on component (B).

[0047] R B6 Examples of the alkenyl group that can be selected as the alkyl group include a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer, and examples of the alkyl group include hydrogenated versions of these groups. Examples of the polybutenyl group include a mixture of 1-butene and isobutene, or a polymerized version of high-purity isobutene. Among these, examples of the alkenyl group include a polybutenyl group and a polyisobutenyl group, and examples of the alkyl group include a polybutenyl group and a hydrogenated version of a polyisobutenyl group. In the lubricating oil composition of this embodiment, R B6 Groups that can be selected for include alkenyl groups, and among alkenyl groups, for example, polybutenyl groups can be mentioned.

[0048] R B7 Examples of the alkylene group having 1 to 6 carbon atoms that can be selected as include a methylene group; various ethylene groups such as a 1,1-ethylene group and a 1,2-ethylene group; various propylene groups such as 1,3-propylene, 1,2-propylene, and 2,2-propylene; various butylene groups; various pentylene groups; and various hexylene groups. Also, R B7The number of carbon atoms of the alkylene group that can be selected as

[0049] R B8 Examples of the alkyl group that can be selected as the alkyl group include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 1,1-dimethylhexyl group, a 2-ethylhexyl group, a nonyl group, a 1,1-dimethylheptyl group, and a decyl group. Examples of the alkylene group having 2 to 4 carbon atoms represented by A2 include an ethylene group, a trimethylene group, and various butylene groups. y is, for example, an integer of 1 to 5, or an integer of 1 to 3.

[0050] In the above general formula (b2), n2 is, for example, 1 to 15, or 2 to 10, or 2 to 5, or 3 or 4.

[0051] Alkenylsuccinic acid monoimides or alkylsuccinic acid monoimides can be usually produced by reacting an alkenylsuccinic anhydride obtained by reacting a polyolefin with maleic anhydride, or an alkylsuccinic anhydride obtained by hydrogenating the alkenylsuccinic anhydride, with a polyamine. As the olefin monomer forming the polyolefin, one or more types selected from α-olefins having 2 to 8 carbon atoms can be mixed and used, for example, a mixture of isobutene and 1-butene is used. On the other hand, examples of polyamines include diamines such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine, and polyalkylenepolyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine, dibutylenetriamine, tributylenetetramine, and pentapentylenehexamine.

[0052] In this embodiment, the content of the non-boronated monoimide dispersant (B'1) is, for example, 1.00 mass % to 3.00 mass % based on the total amount of the lubricating oil composition.

[0053] <Content ratio of non-boronated bisimide dispersant (B) and boronated imide dispersant (B'2)> As described above, the lubricating oil composition of this embodiment exhibits the effects of the present invention and, from the viewpoint of improving the detergency of the lubricating oil composition, it is desirable to use a combination of a non-boronated bisimide dispersant (B) and a boronated imide dispersant (B'2). In this case, the content ratio of the non-boronated bisimide dispersant (B) to the boronated imide dispersant (B'2) [(B) / (B'2)], expressed by mass ratio, is preferably 12.0 to 35.0, more preferably 14.0 to 29.5, and even more preferably 16.0 to 24.0.

[0054] <Alkali metal borates (C)> The lubricating oil composition of this embodiment contains a certain amount of an alkali metal borate (C) in combination with a non-boronated bisimide dispersant (B) and a primary zinc dialkyldithiophosphate (D).

[0055] In the lubricating oil composition of this embodiment, the content (blended amount) of the alkali metal borate (C) is preferably 0.1 to 0.29 mass%, more preferably 0.15 to 0.28 mass%, and even more preferably 0.20 to 0.26 mass%, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of controlling the boron atom content in the lubricating oil composition to 200 ppm or less, based on the total amount of the lubricating oil composition.

[0056] The alkali metal atom contained in the alkali metal borate (C) is preferably a potassium atom or a sodium atom, and more preferably a potassium atom. A borate is an electropositive compound (salt) that contains boron and oxygen and is optionally hydrated. An example of a borate is the borate ion (BO 3- ) salts and metaborate ion (BO2 -) salts. In addition, borate ions (BO3 3- ) is, for example, the triborate ion (B3O5 - ), tetraborate ion (B4O7 2- ), pentaboric acid ion (B5O8 - ) can form various polymer ions.

[0057] Examples of the alkali metal borate (C) include sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, sodium diborate, potassium metaborate, potassium triborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, and potassium octaborate, and are preferably the alkali metal borate represented by the following general formula (c1). General formula (c1): MO 1 / 2 mBO 3 / 2 In the above general formula (c1), M represents an alkali metal atom, preferably a potassium atom or a sodium atom, and more preferably a potassium atom, and m represents a number from 2.5 to 4.5.

[0058] The alkali metal borate (C) may also be a hydrate. Examples of the hydrates of alkali metal borate include Na2B4O7·10H2O, NaBO2·4H2O, KB3O5·4H2O, K2B4O7·5H2O, K2B4O7·8H2O, and KB5O8·4H2O, and are preferably the hydrates of alkali metal borate represented by the following general formula (c2): General formula (c2): MO 1 / 2 mBO 3 / 2 pH2O In the above general formula (c2), M and m are the same as in the above general formula (c1), and p represents a number of 0.5 to 2.4.

[0059] In the lubricating oil composition of this embodiment, these alkali metal borates (C) may be used alone or in combination of two or more.

[0060] <Zinc primary dialkyldithiophosphate (D)> The lubricating oil composition of this embodiment further contains a certain amount of primary zinc dialkyl dithiophosphate (D). The lubricating oil composition contains a certain amount of primary zinc dialkyl dithiophosphate (D) in addition to the non-boronated bisimide dispersant (B) and the alkali metal borate (C), thereby improving metal corrosion inhibition. The reason is unclear, but it is presumed that, for example, primary zinc dialkyl dithiophosphate (D) prevents oxidation of the lubricating oil composition and biofuel, and inhibits the generation of polar compounds together with the component (B). As the primary zinc dialkyldithiophosphate (D), those that have been widely used as additives for lubricating oils can be used without any particular limitation. The primary zinc dialkyldithiophosphate (D) may be used alone or in combination of two or more.

[0061] An example of the primary zinc dialkyldithiophosphate (D) is a compound represented by the following general formula (d1).

[0062] [ka] (In the formula, R D1 ~R D4 each independently represents a hydrocarbon group.

[0063] In primary zinc dialkyldithiophosphate (D), R D1 ~R D4 The hydrocarbon group represented by is a linear alkyl group having 1 to 24 carbon atoms, and the number of carbon atoms in the linear alkyl group is preferably 4 to 12, more preferably 6 to 10, and further preferably 7 to 9. Examples of the linear alkyl group having 1 to 24 carbon atoms include a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, and an icosyl group, and among these, an octyl group is preferred.

[0064] (Content of primary zinc dialkyldithiophosphate (D)) In the lubricating oil composition of this embodiment, the content of primary zinc dialkyldithiophosphate (D) is preferably 0.10 mass% or more, more preferably 0.30 mass% or more, and even more preferably 0.40 mass% or more based on the total amount of the lubricating oil composition from the viewpoint of easily improving the effects of the present invention. Also, from the viewpoint of suppressing an increase in the friction coefficient, it is preferably 5.00 mass% or less, more preferably 3.00 mass% or less, and even more preferably 1.00 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 0.10 mass % to 5.00 mass %, more preferably 0.30 mass % to 3.00 mass %, and even more preferably 0.40 mass % to 1.00 mass %.

[0065] <Other zinc dithiophosphates (D')> The lubricating oil composition of this embodiment may further contain, in addition to the above-mentioned zinc primary dialkyldithiophosphate (D), another zinc dithiophosphate (D'). Other examples of zinc dithiophosphates (D') include compounds represented by the above general formula (d1) other than the primary dialkyl zinc dithiophosphates (D). D1 ~R D4 Examples of the hydrocarbon group represented by the formula (I) include a branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 3 to 24 carbon atoms, a cycloalkyl group or a linear or branched alkylcycloalkyl group having 5 to 13 carbon atoms, an aryl group having 6 to 18 carbon atoms, a linear or branched alkylaryl group having 7 to 19 carbon atoms, and an arylalkyl group having 7 to 19 carbon atoms.

[0066] (Other zinc dithiophosphate (D') content) In the lubricating oil composition of this embodiment, the content of the other zinc dithiophosphate (D') is, for example, 0.30 mass % to 3.00 mass % based on the total amount of the lubricating oil composition.

[0067] <Metal-based detergents (E), viscosity index improvers (F), and pour point depressants (G)> The lubricating oil composition of the present embodiment preferably contains, in addition to components (A) to (D), one or more selected from the group consisting of a metallic detergent (E), a viscosity index improver (F), and a pour point depressant (G), more preferably contains two or more, and even more preferably contains all of them.

[0068] <Metal-based cleaning agents (E)> The lubricating oil composition of this embodiment can further improve the detergency by containing a specified amount of the metallic detergent (E). From the viewpoint of improving detergency, the metal atom contained in the metal-based detergent (E) is preferably one or more metal atoms selected from the group consisting of alkali metal atoms and alkaline earth metal atoms, more preferably sodium atom, calcium atom, magnesium atom, and barium atom, even more preferably calcium atom and magnesium atom, and even more preferably calcium atom. In addition, the metal-based detergent (E) is preferably a metal phenate, a metal sulfonate, and a metal salicylate. That is, the metal-based detergent (E) is preferably one or more selected from the group consisting of calcium phenate, calcium sulfonate, and calcium salicylate, more preferably contains two or more, and even more preferably contains all of them. The content of the metallic detergent (E) is preferably 1.00 mass% or more, more preferably 1.50 mass% or more, and even more preferably 2.00 mass% or more, based on the total amount of the lubricating oil composition, and is preferably 4.00 mass% or less, more preferably 3.50 mass% or less, and even more preferably 3.00 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 1.00 mass % to 4.00 mass %, more preferably 1.50 mass % to 3.50 mass %, and even more preferably 2.00 mass % to 3.00 mass %.

[0069] The calcium phenate is preferably a compound represented by the following general formula (e1), the calcium sulfonate is preferably a compound represented by the following general formula (e2), and the calcium salicylate is preferably a compound represented by the following general formula (e3).

[0070] [ka]

[0071] In the above general formulas (e1) to (e3), R E1 ~R E4 are each independently a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms. q is an integer of 0 or more, and preferably an integer of 0 to 3. R E1 ~R E4 Examples of the hydrocarbon group that can be selected as the aryl group include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an aryl group having 6 to 18 ring carbon atoms, an alkylaryl group having 7 to 18 carbon atoms, and an arylalkyl group having 7 to 18 carbon atoms. These may be used alone or in combination of two or more.

[0072] <Calcium sulfide phenate (E1)> The calcium phenate is preferably a sulfurized calcium phenate (E1) containing a sulfur atom in its molecular structure. The content of the sulfur atom in the sulfurized calcium phenate (E1) is preferably 1.00 to 8.00 mass%, more preferably 2.00 to 6.00 mass%, even more preferably 2.30 to 5.00 mass%, and still more preferably 2.50 to 4.00 mass%. The sulfurized calcium phenate (E1) may be any of a neutral salt, a basic salt, an overbased salt or a mixture thereof, with a basic salt being particularly preferred. When the calcium sulfide phenate (E1) is a neutral salt, the base number of the neutral salt is preferably 0 to 30 mgKOH / g, more preferably 0 to 25 mgKOH / g, and further preferably 0 to 20 mgKOH / g. When the calcium sulfide phenate (E1) is a basic salt or an overbased salt, the base number of the basic salt or the overbased salt is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, even more preferably 160 to 500 mgKOH / g, and still more preferably 200 to 450 mgKOH / g. In this specification, the "base number" refers to the base number measured by the perchloric acid method in accordance with 9 of JIS K2501:2003 "Petroleum products and lubricants -- Determination of neutralization number". When the metallic detergent (E) contains the sulfurized calcium phenate (E1), the content of the sulfurized calcium phenate (E1) in the metallic detergent (E) is preferably 0.10 mass% to 1.00 mass%, more preferably 0.20 mass% to 0.80 mass%, and even more preferably 0.30 mass% to 0.60 mass%, based on the total amount of the lubricating oil composition.

[0073] <Overbased Calcium Sulfonate (E2)> The calcium sulfonate is particularly preferably an overbased calcium sulfonate (E2). The base number of the overbased calcium sulfonate (E2) is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, even more preferably 160 to 500 mgKOH / g, and still more preferably 200 to 450 mgKOH / g. When the metallic detergent (E) contains an overbased calcium sulfonate (E2), the content of the overbased calcium sulfonate (E2) in the metallic detergent (E) is preferably 0.50 mass% to 2.00 mass%, more preferably 0.60 mass% to 1.50 mass%, and even more preferably 0.75 mass% to 1.25 mass%, based on the total amount of the lubricating oil composition.

[0074] <Overbased calcium salicylate (E3)> The calcium salicylate is particularly preferably an overbased calcium salicylate (E3). The base number of the overbased calcium salicylate (E3) is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, even more preferably 140 to 500 mgKOH / g, and still more preferably 160 to 450 mgKOH / g. When the metallic detergent (E) contains an overbased calcium salicylate (E3), the content of the overbased calcium salicylate (E3) in the metallic detergent (E) is preferably 0.50 mass% to 2.00 mass%, more preferably 0.60 mass% to 1.50 mass%, and even more preferably 0.75 mass% to 1.25 mass%, based on the total amount of the lubricating oil composition.

[0075] <Content ratio of sulfurized calcium phenate (E1), overbased calcium sulfonate (E2), and overbased calcium salicylate (E3)> From the viewpoint of further improving detergency, as described above, the lubricating oil composition of the present embodiment preferably contains one or more compounds selected from the group consisting of the sulfurized calcium phenate (E1), the overbased calcium sulfonate (E2), and the overbased calcium salicylate (E3), more preferably contains two or more compounds, and even more preferably contains all of them. When two or more compounds selected from the group consisting of the sulfurized calcium phenate (E1), the overbased calcium sulfonate (E2), and the overbased calcium salicylate (E3) are contained, from the viewpoint of further improving detergency, the content ratio of the sulfurized calcium phenate (E1) to the overbased calcium sulfonate (E2) [(E1) / (E2)], expressed by mass, is preferably 0.1 to 1.5, more preferably 0.2 to 1.2, and even more preferably 0.3 to 0.6. The content ratio of the overbased calcium salicylate (E3) to the overbased calcium sulfonate (E2) [(E3) / (E2)], expressed by mass ratio, is preferably 0.2 to 2.0, more preferably 0.4 to 1.6, and even more preferably 0.6 to 1.2.

[0076] <Viscosity index improver (F)> Examples of the viscosity index improver (F) include non-dispersant polymethacrylate (PMA), dispersant polymethacrylate, olefin copolymers (olefin copolymers (OCPs); e.g., ethylene-propylene copolymers, etc.), dispersant olefin copolymers, and styrene copolymers (e.g., hydrogenated styrene-diene copolymers, etc.). These may be used alone or in combination of two or more. Here, as the viscosity index improver (F), it is preferable to use a hydrogenated styrene-diene copolymer. The mass average molecular weight (Mw) of the hydrogenated styrene-diene copolymer is preferably within a range of 100,000 to 1,100,000, and more preferably within a range of 200,000 to 1,000,000. The mass average molecular weight (Mw) of the viscosity index improver (F) is a value measured by gel permeation chromatography and calculated in terms of polystyrene. The content of the viscosity index improver (F) is preferably from 2.00 mass % to 8.00 mass %, and more preferably from 4.00 mass % to 6.00 mass %, based on the total amount of the lubricating oil composition.

[0077] <Pour point depressant (G)> Examples of the pour point depressant (G) include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, polyalkylstyrenes, and other polymers. These may be used alone or in combination of two or more. Here, it is preferable to use polymethacrylate as the pour point depressant (G). Moreover, the polymethacrylate preferably has a mass average molecular weight (Mw) within the range of 50,000 to 150,000. The mass average molecular weight (Mw) of the pour point depressant (G) is a value measured by gel permeation chromatography and calculated in terms of polystyrene. The content of the pour point depressant (G) is preferably 0.05 to 0.50 mass %, and more preferably 0.10 to 0.30 mass %, based on the total amount of the lubricating oil composition.

[0078] <Other additives> The lubricating oil composition of the present embodiment may or may not contain components other than component (A), component (B), component (C), component (D), component (E), component (F), and component (G) (hereinafter also referred to as "other additives"), provided that the effects of the present invention are not significantly impaired. Examples of other additives include antioxidants, rust inhibitors, metal deactivators, corrosion inhibitors, load-bearing additives (extreme pressure agents, friction modifiers, oiliness agents), and antifoaming agents. These may be used alone or in combination of two or more. In the lubricating oil composition of this embodiment, the total content of other additives is preferably 0.00 mass% to 10.00 mass%, more preferably 0.10 mass% to 5.00 mass%, even more preferably 0.50 mass% to 3.00 mass%, and still more preferably 0.50 mass% to 2.00 mass%, based on the total amount of the lubricating oil composition.

[0079] [Physical properties of lubricating oil composition] <40℃ kinematic viscosity, 100℃ kinematic viscosity> The lubricating oil composition of the present embodiment preferably has a kinematic viscosity at 40°C of 13.5 mm 2 / s~506mm 2 / s, more preferably 28.8 mm 2 / s~352mm 2 / s, and more preferably 41.4 mm 2 / s~242mm 2 / s. The lubricating oil composition of the present embodiment preferably has a kinematic viscosity at 100°C of 4.0 mm 2 / s or more 26.1mm 2 / s, preferably less than 5.0 mm 2 / s or more 21.9mm 2 / s, more preferably less than 6.1 mm 2 / s or more 16.3mm 2 / s. In this specification, the 40° C. kinematic viscosity and 100° C. kinematic viscosity of a lubricating oil composition refer to values ​​measured in accordance with JIS K2283:2000.

[0080] <Base number by perchloric acid method> The lubricating oil composition of the present embodiment has a base number of preferably 4.00 mgKOH / g or more, more preferably 6.00 mgKOH / g or more, even more preferably 8.00 mgKOH / g or more, and preferably 16.00 mgKOH / g or less, more preferably 14.00 mgKOH / g or less, even more preferably 12.00 mgKOH / g or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 4.00 mgKOH / g to 16.00 mgKOH / g, more preferably 6.00 mgKOH / g to 14.00 mgKOH / g, and even more preferably 8.00 mgKOH / g to 12.00 mgKOH / g. The base number of the lubricating oil composition is the base number measured by the perchloric acid method in accordance with 9 of JIS K2501:2003 "Petroleum products and lubricants -- Determination of neutralization number".

[0081] <Various atomic contents> (Nitrogen atom content) The nitrogen atom content in the lubricating oil composition of this embodiment is preferably 600 ppm by mass or more, more preferably 800 ppm by mass or more, and even more preferably 1000 ppm by mass or more, based on the total amount (100 mass%) of the lubricating oil composition. From the viewpoint of low viscosity, the nitrogen atom content is preferably 1600 ppm by mass or less, more preferably 1400 ppm by mass or less, and even more preferably 1200 ppm by mass or less, based on the total amount (100 mass%) of the lubricating oil composition. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 600 ppm by mass to 1600 ppm by mass, more preferably 800 ppm by mass to 1400 ppm by mass, and even more preferably 1000 ppm by mass to 1200 ppm by mass. The nitrogen atom content can be measured in accordance with JIS K 2609:1998.

[0082] (Boron atom content) From the viewpoint of making it easier to improve the effects of the present invention, the content of boron atoms in the lubricating oil composition of this embodiment is preferably 70 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 140 ppm by mass or more, and even more preferably 170 ppm by mass or more, based on the total amount (100 mass%) of the lubricating oil composition. Also, it is preferably 270 ppm by mass or less, more preferably 250 ppm by mass or less, even more preferably 200 ppm by mass or less, and even more preferably 190 ppm by mass or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 70 ppm by mass to 270 ppm by mass, more preferably 100 ppm by mass to 250 ppm by mass, even more preferably 140 ppm by mass to 200 ppm by mass, and even more preferably 170 ppm by mass to 190 ppm by mass. The boron atom content can be measured in accordance with JPI-5S-38-03.

[0083] <Amount of lead eluted after corrosion test> In the lubricating oil composition of this embodiment, after a corrosiveness test is carried out by the method described in the Examples described below, the amount of lead (Pb) eluted into the sample oil is preferably 300 ppm by mass or less, more preferably 270 ppm by mass or less, even more preferably 260 ppm by mass or less, and still more preferably 220 ppm by mass or less, based on the total amount (100 mass%) of the lubricating oil composition. The amount of lead (Pb) leaching can be measured in accordance with JPI-5S-38-03.

[0084] [Method of manufacturing lubricating oil composition] The method for producing the lubricating oil composition of this embodiment is not particularly limited. For example, a method for producing a lubricating oil composition of the present embodiment includes the steps of mixing a base oil (A), a non-boronated bisimide dispersant (B), an alkali metal borate (C), and a primary zinc dialkyldithiophosphate (D); In the above step, the non-boronated bisimide dispersant (B) is blended in an amount of 3.00 mass % or more based on the total amount of the lubricating oil composition. In the above steps, when additives other than components (A) to (D) are added, the additives may be added simultaneously with components (A) to (D) or may be added separately. Also, each component may be added with a diluent oil or the like to form a solution (dispersion) before being added. After mixing the components, it is preferable to stir them by a known method to disperse them uniformly. The preferred embodiments of each of the above components are as described above.

[0085] [Uses of lubricating oil composition] The lubricating oil composition of the present embodiment is excellent in inhibiting metal corrosion of engine parts, even when a fuel containing a biofuel is used in an internal combustion engine. Therefore, the lubricating oil composition of the present embodiment can be widely used in internal combustion engines that use fuels including biofuels, and among these, can be particularly suitably used in diesel engines. According to the present embodiment, there is also provided use of the lubricating oil composition as a lubricating oil composition for an internal combustion engine using a fuel containing a biofuel.

[0086] [Lubrication method using lubricating oil composition] The lubrication method of the present embodiment is a lubrication method in which the lubricating oil composition of the present embodiment is used in an internal combustion engine using a fuel containing a biofuel.

[0087] [One aspect of the present invention provided] In one embodiment of the present invention, the following [1] to [9] are provided. [1] A lubricating oil composition for use in an internal combustion engine using a fuel containing a biofuel, A lubricant composition comprising: a base oil (A); a non-boronated bisimide dispersant (B); an alkali metal borate (C); and a primary zinc dialkyldithiophosphate (D); A lubricating oil composition, wherein the content of the non-boronated bisimide dispersant (B) is 3.00 mass% or more based on the total amount of the lubricating oil composition. [2] The lubricating oil composition according to the above [1], further comprising 1.50 mass% or less of a boronated imide dispersant (B'2) based on the total amount of the lubricating oil composition. [3] The lubricating oil composition according to the above [1] or [2], wherein the content of the alkali metal borate (C) is 0.1 to 0.29 mass% based on the total amount of the lubricating oil composition. [4] The lubricating oil composition according to any one of the above [1] to [3], wherein the content of the zinc primary dialkyldithiophosphate (D) is 0.55 mass% or more based on the total amount of the lubricating oil composition. [5] The lubricating oil composition according to any one of the above [1] to [4], wherein the boron content in the lubricating oil composition is 200 ppm by mass or less based on the total amount of the lubricating oil composition. [6] The lubricating oil composition according to any one of the above [1] to [5], further comprising one or more selected from the group consisting of a metallic detergent (E), a viscosity index improver (F), and a pour point depressant (G). [7] The lubricating oil composition according to the above item [6], comprising, as the metallic detergent (E), one or more selected from the group consisting of sulfurized calcium phenate (E1), overbased calcium sulfonate (E2), and overbased calcium salicylate (E3). [8] A method for producing a lubricating oil composition for use in an internal combustion engine using a fuel containing a biofuel, comprising the steps of: The method includes the steps of: mixing a base oil (A), a non-boronated bisimide dispersant (B), an alkali metal borate (C), and a primary zinc dialkyldithiophosphate (D); In the above step, the non-boronated bisimide dispersant (B) is blended in an amount of 3.00 mass% or more based on the total amount of the lubricating oil composition. [9] A lubrication method comprising using the lubricating oil composition according to any one of the above [1] to [7] in an internal combustion engine using a fuel containing a biofuel. EXAMPLES

[0088] The present invention will be described in more detail with reference to the following examples, although the present invention is not limited to the following examples.

[0089] [Methods for measuring various physical properties] The properties of the raw materials used in each Example and Comparative Example and the lubricating oil compositions in each Example and Comparative Example were measured according to the procedures described below.

[0090] (1)Kinematic viscosity at 40℃, kinematic viscosity at 100℃ Measurements were performed in accordance with JIS K2283:2000. (2) Base number The measurement was performed using the perchloric acid method in accordance with 9. of JIS K2501:2003 "Petroleum products and lubricants - Test method for neutralization number". (3) Atomic content The nitrogen atom content was measured in accordance with JIS K 2609:1998. The boron atom content was measured in accordance with JPI-5S-38-03. (4) Mass average molecular weight (Mw) The mass average molecular weight (Mw) of each dispersant described later was calculated in terms of standard polystyrene using a GPC device (device name: 1260Infinity, manufactured by Agilent Technologies) under the following measurement conditions. Column: 2 "LF-404" (Shodex Co., Ltd.) Detector: Refractive index detector ·Measurement temperature: 35℃ Mobile phase: Chloroform ·Flow rate: 0.3mL / min ·Concentration: 0.2wt% The mass average molecular weight (Mw) of the viscosity index improver (F) and the pour point depressant (G) described below was calculated for each compound using a GPC apparatus (apparatus name: 1260Infinity, manufactured by Agilent Technologies) under the same measurement conditions as those described above, in terms of polystyrene.

[0091] [Examples 1 to 5, Comparative Examples 1 to 7] Lubricating oil compositions having the compositions shown in Table 1 were prepared by mixing the components below, and the following evaluations were carried out. The components used in preparing the lubricating oil compositions shown in Table 1 are described in detail below.

[0092] <Base oil (A)> ·Base oil A: Mineral oil (40℃ kinematic viscosity = 29.62mm 2 / s, 100℃ kinematic viscosity=5.366mm 2 / s) ·Base oil B: Mineral oil (40℃ kinematic viscosity = 91.50mm 2 / s, 100℃ kinematic viscosity=10.50mm 2 / s)

[0093] <Dispersant> Non-boronated imide dispersant: Non-boronated polybutenyl succinic acid bisimide (B-1): (mass average molecular weight (Mw): 26,000, nitrogen atom content: 1.0% by mass) Imide dispersant A: Non-boronated polybutenyl succinic acid bisimide (B-2) (mass average molecular weight (Mw): 26,000, nitrogen atom content: 1.0% by mass) Imide dispersant B: Non-boronated polybutenyl succinic acid bisimide (B-3) (mass average molecular weight (Mw): 15,000, nitrogen atom content: 1.08% by mass) Imide dispersant C: Non-boronated polybutenyl succinic acid bisimide (B-4) (mass average molecular weight (Mw): 45,000, nitrogen atom content: 1.2% by mass) Imide dispersant D: Non-boronated polybutenyl succinic acid bisimide (B-5) (mass average molecular weight (Mw): 5,200, nitrogen atom content: 2.0% by mass) Imide dispersant E: Non-boronated polybutenyl succinic acid bisimide (B-6): (mass average molecular weight (Mw): 5,700, nitrogen atom content: 1.15% by mass) Imide dispersant F: Non-boronated polybutenyl succinic acid monoimide (B'1-1): (mass average molecular weight (Mw): 38,000, nitrogen atom content: 2.13% by mass) Imide dispersant G: Non-boronated polybutenyl succinic acid monoimide (B'1-2): (mass average molecular weight (Mw): 36,000, nitrogen atom content: 2.1% by mass) Boronized imide dispersant: Boronized succinimide (B'2-1): (mass average molecular weight (Mw): 47,000, nitrogen atom content: 1.5 mass%, boron atom content: 0.49 mass%) Imide dispersant H: boronized succinimide (B'2-2): (mass average molecular weight (Mw): 47,000, nitrogen atom content: 1.5 mass%, boron atom content: 0.49 mass%) Imide dispersant I: boronized succinimide (B'2-3): (mass average molecular weight (Mw): 174,000, nitrogen atom content: 2.3 mass%, boron atom content: 1.9 mass%) Imide dispersant J: boronized succinimide (B'2-4): (mass average molecular weight (Mw): 16,000, nitrogen atom content: 1.23 mass%, boron atom content: 1.3 mass%) Imide dispersant K: boronized succinimide (B'2-5): (mass average molecular weight (Mw): 36,000, nitrogen atom content: 1.25 mass%, boron atom content: 1.3 mass%) Imide dispersant L: boronized succinimide (B'2-6): (mass average molecular weight (Mw): 136,000, nitrogen atom content: 1.76 mass%, boron atom content: 1.9 mass%)

[0094] <Alkali metal borates (C)> Potassium borate: Microparticle dispersion of potassium borate hydrate (Potassium atom content: 8.0% by mass, Boron atom content: 6.8% by mass)

[0095] <Zinc primary dialkyldithiophosphate (D)> Primary zinc dialkyldithiophosphate (phosphorus atom content: 7.4% by mass, zinc atom content: 9.03% by mass, sulfur atom content: 15% by mass, number of carbon atoms in alkyl group: 8) In the table, it is referred to as "primary ZnDTP."

[0096] <Metal-based cleaning agents (E)> Calcium sulfide phenate (E1): Basic calcium sulfide phenate (base number: 250 mg KOH / g, calcium atom content: 9.3 mass%, sulfur atom content: 3.3 mass%) Overbased calcium sulfonate (E2): Overbased calcium sulfonate (base number: 425 mg KOH / g, calcium atom content: 16.1% by mass) Overbased calcium salicylate (E3): Overbased calcium salicylate (base number: 170 mg KOH / g, calcium atom content: 6.1% by mass)

[0097] <Viscosity index improver (F)> Hydrogenated styrene-diene copolymer (mass average molecular weight (Mw): 600,000, (Mw / Mn): 1.9)

[0098] <Pour point depressant (G)> Polymethacrylate (VISCOPLEX (registered trademark) 1-156 (EVONIK))

[0099] <Other additives> Phenol-based antioxidants, benzotriazole derivatives, antifoaming agents, etc.

[0100] [Lead elution amount after corrosion test] As the lubricating oil composition for testing, a mixed oil was used in which 10 mass% of biofuel (fuel obtained by transesterifying palm oil with methyl alcohol) was blended with each of the above-mentioned lubricating oil compositions (new oil), assuming the mixing ratio of fuel and lubricating oil in an internal combustion engine. The corrosion test was carried out as follows. 100ml of each mixed oil sample was filled into a glass container (40mm diameter x 30mm height), and a polished lead plate (25mm x 25mm x 1.0mm) was immersed completely in the sample oil. Then, air was blown into the sample oil at 5l / hr while maintaining the oil temperature at 135°C. The amount of lead (Pb) dissolved in the sample oil was measured by inductively coupled plasma emission spectrometry (ICP) in accordance with JPI-5S-38-03. The smaller the amount of lead (Pb) dissolved, the better the corrosion inhibition.

[0101] The properties and corrosiveness test results of each lubricating oil composition are shown in Table 1. [Table 1]

[0102] <Evaluation Results> From Table 1, we can see the following: The lubricating oil compositions of Examples 1 to 5 had a small amount of lead (Pb) eluted in the corrosivity test, and are therefore excellent in corrosion inhibition properties. In contrast, lubricating oil compositions that do not contain 3.00 mass% or more of the non-boronated bisimide dispersant (B) based on the total amount of the lubricating oil composition, such as the lubricating oil compositions of Comparative Examples 1 to 7, eluted a larger amount of lead (Pb) in the corrosivity test than Examples 1 to 5, and were found to have inferior corrosion inhibition properties.

Claims

1. A lubricating oil composition for use in an internal combustion engine using a fuel containing a biofuel, comprising: A lubricant composition comprising: a base oil (A); a non-boronated bisimide dispersant (B); an alkali metal borate (C); and a primary zinc dialkyldithiophosphate (D); The lubricating oil composition has a content of the non-boronated bisimide dispersant (B) of 3.00 mass% or more based on the total amount of the lubricating oil composition.

2. 2. The lubricating oil composition according to claim 1, further comprising up to 1.50 mass % of a boronated imide dispersant (B'2), based on the total amount of the lubricating oil composition.

3. 3. The lubricating oil composition according to claim 1, wherein the content of the alkali metal borate (C) is 0.1 to 0.29 mass % based on the total amount of the lubricating oil composition.

4. The lubricating oil composition according to any one of claims 1 to 3, wherein the content of the primary zinc dialkyldithiophosphate (D) is 0.30 mass% or more based on the total amount of the lubricating oil composition.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein the boron content in the lubricating oil composition is 200 ppm by mass or less based on the total amount of the lubricating oil composition.

6. The lubricating oil composition according to any one of claims 1 to 5, further comprising one or more selected from the group consisting of a metal-based detergent (E), a viscosity index improver (F), and a pour point depressant (G).

7. 7. The lubricating oil composition according to claim 6, wherein the metal-based detergent (E) is one or more selected from the group consisting of sulfurized calcium phenate (E1), overbased calcium sulfonate (E2), and overbased calcium salicylate (E3).

8. A method for producing a lubricating oil composition for use in an internal combustion engine using a fuel including a biofuel, comprising the steps of: The method includes the steps of: mixing a base oil (A), a non-boronated bisimide dispersant (B), an alkali metal borate (C), and a primary zinc dialkyldithiophosphate (D); In the step, the non-boronated bisimide dispersant (B) is blended in an amount of 3.00 mass% or more based on the total amount of the lubricating oil composition.

9. A method of lubricating an internal combustion engine using a fuel containing a biofuel, comprising using a lubricating oil composition according to any one of claims 1 to 7.

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