Lubricating oil compositions and methods of use and manufacturing thereof

Abstract

Specifically disclosed is a lubricating oil composition which contains a vegetable oil (A), zinc dithiophosphate (B) and an amine-based antioxidant (C), and which is characterized in that: the total content of linoleic acid and linolenic acid among fatty acids constituting the vegetable oil (A) is less than 20% by mass based on the total amount of fatty acids constituting the vegetable oil (A); the content of the amine-based antioxidant (C) is 2.00 mass% or more based on the total amount of the lubricating oil composition, and when the lubricating oil composition further contains a phosphorus-free phenolic antioxidant (D), the content of the phosphorus-free phenolic antioxidant (D) is less than 2.00 mass% based on the total amount of the lubricating oil composition.

Description

Technical Field

[0001] The present invention relates to lubricating oil compositions and methods of using and making the same. Background Art

[0002] In recent years, the introduction of the concept of carbon neutrality has led to the flexible use of plant-derived raw materials. In the field of lubricants, the use of plant oils as base oils has also been studied.

[0003] For example, Patent Document 1 proposes an animal or vegetable lubricating oil having a low melting point, high viscosity and high stability, which has an isolated trans isomer content of 40% by mass or more in triglyceride-constituting fatty acids and an iodine value of 50 to 90.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 8-311466 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, Patent Document 1 only studies the base oil, and does not study the form of the lubricating oil composition including the additive ratio.

[0009] An object of the present invention is to provide a lubricating oil composition which uses a vegetable oil as a base oil and has excellent oxidation stability, and a method for using and a method for producing the same.

[0010] Means used to solve problems

[0011] According to the present invention, the following [1] to [3] are provided.

[0012] [1] A lubricating oil composition comprising a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C),

[0013] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0014] The content of the amine antioxidant (C) is 2.00 mass % or more based on the total amount of the lubricating oil composition.

[0015] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the content of the non-phosphorus-containing phenolic antioxidant (D) is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0016] [2] A method for using the lubricating oil composition, comprising using the lubricating oil composition described in [1] as an industrial equipment oil.

[0017] [3] A method for producing a lubricating oil composition, comprising: mixing a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C) to prepare the lubricating oil composition;

[0018] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0019] The amount of the amine antioxidant (C) is 2.00% by mass or more based on the total amount of the lubricating oil composition.

[0020] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the amount of the non-phosphorus-containing phenolic antioxidant (D) contained is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0021] Effects of the Invention

[0022] According to the present invention, a lubricating oil composition using a vegetable oil as a base oil and having excellent oxidation stability, and a method for using and a method for producing the same can be provided. DETAILED DESCRIPTION

[0023] The upper limit and lower limit of the numerical range described in this specification can be arbitrarily combined. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges of "A to D" and "C to B" are also included in the scope of the present invention.

[0024] In addition, the numerical range "lower limit value - upper limit value" described in this specification means more than the lower limit value and less than the upper limit value unless otherwise specified.

[0025] In addition, in this specification, the numerical values ​​of Examples are numerical values ​​that can be used as upper limits or lower limits.

[0026] [Embodiments of Lubricating Oil Composition]

[0027] The lubricating oil composition of the present embodiment contains a vegetable oil (A), zinc dithiophosphate (B), and an amine antioxidant (C).

[0028] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0029] The content of the amine antioxidant (C) is 2.00% by mass or more based on the total amount of the lubricating oil composition.

[0030] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the content of the non-phosphorus-containing phenolic antioxidant (D) is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0031] The present inventors have conducted intensive studies to solve the above problems and have found that the following (I) to (IV) are important in preparing a lubricating oil composition having excellent oxidation stability using a vegetable oil as a base oil.

[0032] (I) A vegetable oil in which the total content of linoleic acid and linolenic acid among the fatty acids constituting the vegetable oil is less than 20% by mass based on the total amount of the constituent fatty acids is used.

[0033] (II) Contains zinc dithiophosphate and an amine antioxidant.

[0034] (III) The content of the amine antioxidant is 2.00% by mass or more.

[0035] (IV) The content of the non-phosphorus-containing phenolic antioxidant is less than 2.00% by mass.

[0036] The mechanism by which the lubricating oil composition of the present embodiment has excellent oxidation stability is not yet clear, but it is presumed that, for a vegetable oil having a specific chemical structure satisfying the above-mentioned (I), the effect of improving oxidation stability by satisfying the above-mentioned specific additive ratios (II) to (IV) is extremely excellent, resulting in excellent oxidation stability of the lubricating oil composition.

[0037] It should be noted that in the following description, “vegetable oil (A)”, “zinc dithiophosphate (B)”, “amine antioxidant (C)” and “phosphorus-free phenolic antioxidant (D)” are also referred to as “component (A)”, “component (B)”, “component (C)” and “component (D)”, respectively.

[0038] The lubricating oil composition of the present embodiment may consist only of "component (A)", "component (B)" and "component (C)", and may or may not contain "component (D)" and one or more other components selected from "component (A)", "component (B)", "component (C)" and "component (D)" within the scope of the present invention.

[0039] In the lubricating oil composition of the present embodiment, the total content of "component (A)", "component (B)" and "component (C)" is preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total amount of the lubricating oil composition.

[0040] Hereinafter, each component constituting the lubricating oil composition according to the present embodiment will be described in detail.

[0041] <Vegetable Oil (A)>

[0042] The lubricating oil composition of the present embodiment contains a vegetable oil (A) as a base oil.

[0043] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A) (hereinafter also referred to as "Condition 1").

[0044] If the total content of linoleic acid and linolenic acid is 20% by mass or more, the lubricating oil composition is likely to be oxidatively degraded, and the oxidation stability of the lubricating oil composition is likely to be insufficient.

[0045] In addition, "the fatty acid constituting the vegetable oil (A)" refers to the fatty acid in the compound which ester-bonded the fatty acid and glycerin which constitute the vegetable oil.

[0046] Here, from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the total content of linoleic acid and linolenic acid is preferably 18% by mass or less, more preferably 16% by mass or less, and even more preferably 15% by mass or less, based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0047] In addition, from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the content of oleic acid among the fatty acids constituting the vegetable oil (A) is preferably 65% ​​by mass or more based on the total amount of the constituent fatty acids in the vegetable oil (A) (hereinafter also referred to as "Condition 2"). From the same viewpoint, the content of oleic acid is more preferably 70% by mass or more, and further preferably 75% by mass or more based on the total amount of the constituent fatty acids in the vegetable oil (A). In addition, the content of oleic acid is usually less than 85% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0048] Furthermore, from the viewpoint of making it easier to improve the oxidation stability of the lubricating oil composition, the content of saturated fatty acids among the fatty acids constituting the vegetable oil (A) is preferably 3% by mass or more (hereinafter also referred to as "Condition 3"), more preferably 4% by mass or more, and even more preferably 5% by mass or more, based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0049] Examples of the saturated fatty acid that may be contained in the fatty acids constituting the vegetable oil (A) include at least one selected from lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. Palmitic acid is particularly representative.

[0050] Examples of methods for measuring the fatty acid composition of the vegetable oil (A) include a method in which lipids are extracted from the vegetable oil (A) using an organic solvent, the organic solvent is removed by distillation, fatty acid methyl esters are prepared from the obtained lipids, and the extracted lipids are subjected to gas chromatography-mass spectrometry (GC-MS analysis).

[0051] It should be noted that the vegetable oil (A) used in the present embodiment can be listed as: crude oil obtained by pressing and extracting natural vegetable oil raw materials; refined oil after various refining treatments such as filtration to remove floating impurities contained in the crude oil, degumming to remove phospholipids, deacidification to remove free fatty acids, decolorization to remove pigments, and dewaxing to remove wax components; and processed oils and fats after solidification, fractionation, ester exchange, hydrogenation, etc.

[0052] Specific examples of the vegetable oil (A) include olive oil, sunflower oil (preferably high oleic acid type), safflower oil (preferably high oleic acid type), safflower seed oil (preferably high oleic acid type), palm oil, palm kernel oil, coconut oil and the like; and base oils derived from plants such as estolide esters.

[0053] The vegetable oil (A) may be composed of only one kind of vegetable oil, or may be a mixed vegetable oil composed of two or more kinds of vegetable oils. When the vegetable oil (A) is a mixed vegetable oil, the mixed vegetable oil only needs to satisfy the above-mentioned condition 1, preferably further satisfy at least one of the above-mentioned conditions 2 and 3, and more preferably satisfy all of the above-mentioned conditions 1, 2 and 3.

[0054] In the lubricating oil composition of the present embodiment, the content of the vegetable oil (A) is preferably 30% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, and still more preferably 90% by mass or more, based on the total amount of the lubricating oil composition. In addition, from the viewpoint of the blending margin of additives such as the component (B) and the component (C), the content of the vegetable oil (A) is preferably 97.9% by mass or less, based on the total amount of the lubricating oil composition.

[0055] <Zinc dithiophosphate (B)>

[0056] The lubricating oil composition of the present embodiment contains zinc dithiophosphate (B).

[0057] When the lubricating oil composition of the present embodiment does not contain zinc dithiophosphate (B), the lubricating oil composition is likely to be oxidatively degraded, and the oxidation stability of the lubricating oil composition is likely to be insufficient.

[0058] Preferred examples of the zinc dithiophosphate (B) include compounds represented by the following general formula (b-1).

[0059] [Chemistry 1]

[0060]

[0061] In the general formula (b-1), R b1 ~R b4 Each independently represents a monovalent hydrocarbon group. The hydrocarbon group is not particularly limited as long as it is a monovalent hydrocarbon group, and for example, from the viewpoint of improving oxidation stability, preferably alkyl, alkenyl, cycloalkyl, aryl, etc. can be listed. Among these, alkyl is preferred.

[0062] That is, as the zinc dithiophosphate (B) used in the present embodiment, zinc dialkyl dithiophosphate is preferable.

[0063] It should be noted that R b1 ~R b4 The cycloalkyl group and aryl group may be polycyclic groups such as decahydronaphthyl and naphthyl.

[0064] In addition, R b1 ~R b4 The monovalent hydrocarbon group may be a monovalent hydrocarbon group having a substituent containing an oxygen atom and / or a nitrogen atom, such as a hydroxyl group, a carboxyl group, an amino group, an amide group, a nitro group, a cyano group, or a monovalent hydrocarbon group partially substituted with a nitrogen atom, an oxygen atom, a halogen atom, or the like. When the monovalent hydrocarbon group is a cycloalkyl group or an aryl group, it may further have a substituent such as an alkyl group or an alkenyl group.

[0065] Optional R b1 ~R b4 The alkyl group and alkenyl group may be either linear or branched, and are preferably primary groups or secondary groups from the viewpoint of obtaining more excellent oxidation stability. Among them, primary alkyl groups and secondary alkyl groups are preferred, and primary alkyl groups are more preferred.

[0066] That is, the zinc dialkyl dithiophosphate used in the present embodiment is preferably a primary alkyl group or a secondary alkyl group or a combination thereof, more preferably a primary zinc dialkyl dithiophosphate or a secondary zinc dialkyl dithiophosphate or a combination thereof, and still more preferably a primary zinc dialkyl dithiophosphate.

[0067] From the viewpoint of improving oxidation stability, R b1 ~R b4 The number of carbon atoms of the hydrocarbon group is preferably 1 or more, more preferably 2 or more, and further preferably 3 or more, and the upper limit is preferably 24 or less, more preferably 18 or less, further preferably 12 or less, and further preferably 10 or less. When the monovalent hydrocarbon is an alkenyl group, it is preferably 2 or more, more preferably 3 or more, and the upper limit is preferably 24 or less, more preferably 18 or less, further preferably 12 or less, and further preferably 10 or less. In addition, when the monovalent hydrocarbon is a cycloalkyl group, the number of carbon atoms is preferably 5 or more, and the upper limit is preferably 20 or less. When the monovalent hydrocarbon is an aryl group, the number of carbon atoms is preferably 6 or more, and the upper limit is preferably 20 or less.

[0068] From the viewpoint of easily improving the oxidation stability of the lubricating oil composition, the content of the zinc dithiophosphate (B) is preferably 0.10% by mass or more, more preferably 0.20% by mass or more, further preferably 0.30% by mass or more, further preferably 0.40% by mass or more, and still further preferably 0.50% by mass or more, based on the total amount of the lubricating oil composition. From the viewpoint of suppressing sludge precipitation, the content is preferably 1.00% by mass or less, more preferably 0.90% by mass or less, and further preferably 0.80% by mass or less.

[0069] The zinc dithiophosphate (B) may be used alone or in combination of two or more.

[0070] <Amine Antioxidant (C)>

[0071] The lubricating oil composition of the present embodiment contains an amine antioxidant (C). In the lubricating oil composition of the present embodiment, the content of the amine antioxidant (C) must be 2.00% by mass or more based on the total amount of the lubricating oil composition.

[0072] When the amount of the amine antioxidant (C) is less than 2.00% by mass based on the total amount of the lubricating oil composition, the lubricating oil composition is likely to be oxidatively degraded, and the oxidation stability of the lubricating oil composition is likely to be insufficient.

[0073] Here, from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the content of the amine antioxidant (C) is preferably 3.00 mass % or more, more preferably 3.50 mass % or more, and even more preferably 3.80 mass % or more based on the total amount of the lubricating oil composition.

[0074] From the viewpoint of suppressing excessive addition of the amine antioxidant (C) and facilitating appropriate improvement of the oxidation stability of the lubricating oil composition, the content of the amine antioxidant (C) is preferably 8.00% by mass or less, more preferably 7.00% by mass or less, and even more preferably 6.00% by mass or less, based on the total amount of the lubricating oil composition.

[0075] As the amine antioxidant (C), an amine antioxidant generally used as an antioxidant for a lubricating oil composition can be used.

[0076] Here, from the viewpoint of improving the oxidation stability of the lubricating oil composition, the amine antioxidant (C) preferably contains a diphenylamine antioxidant (C1) and a naphthylamine antioxidant (C2).

[0077] From the same viewpoint, the total content of the diphenylamine antioxidant (C1) and the naphthylamine antioxidant (C2) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, further preferably 80% by mass to 100% by mass, further preferably 90% by mass to 100% by mass, and further preferably 95% by mass to 100% by mass, based on the total amount of the amine antioxidant (C).

[0078] Hereinafter, the diphenylamine antioxidant (C1) and the naphthylamine antioxidant (C2) will be described in detail.

[0079] In the following description, the "diphenylamine antioxidant (C1)" and the "naphthylamine antioxidant (C2)" are also referred to as "component (C1)" and "component (C2)", respectively.

[0080] (Diphenylamine antioxidant (C1))

[0081] As the diphenylamine antioxidant (C1), a diphenylamine antioxidant commonly used as an antioxidant for a lubricating oil composition can be used.

[0082] The diphenylamine antioxidant (C1) may be used alone or in combination of two or more.

[0083] Here, in the lubricating oil composition of the present embodiment, the diphenylamine antioxidant (C1) is preferably a compound represented by the following general formula (c1-1) from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition.

[0084] [Chemistry 2]

[0085]

[0086] In the above general formula (c1-1), R c11 and R c12 Each is independently an alkyl group having 1 to 30 carbon atoms.

[0087] When the alkyl group has 1 to 30 carbon atoms, the oxidation stability of the lubricating oil composition can be more easily improved.

[0088] From the viewpoint of making it easier to improve the effect of the present invention, R c11 and R c12 The number of carbon atoms of the alkyl groups is each independently preferably 1 to 20, more preferably 4 to 16, and even more preferably 4 to 14.

[0089] As an optional R c11 and R c12 Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl, etc. These may be linear or branched.

[0090] In the above general formula (c1-1), nc11 and nc12 are each independently an integer of 1 to 5.

[0091] From the viewpoint of making it easier to improve the oxidation stability of the lubricating oil composition, nc11 and nc12 are each independently preferably 1 to 3, more preferably 1 to 2, and even more preferably 1.

[0092] The compound represented by the general formula (c1-1) may be used alone or in combination of two or more.

[0093] (Naphthylamine antioxidant (C2))

[0094] As the naphthylamine antioxidant (C2), a naphthylamine antioxidant commonly used as an antioxidant for a lubricating oil composition can be used.

[0095] The naphthylamine antioxidant (C2) may be used alone or in combination of two or more.

[0096] Here, in the lubricating oil composition of the present embodiment, the naphthylamine antioxidant (C2) is preferably a compound represented by the following general formula (c2-1) from the viewpoint of more easily enhancing the effects of the present invention.

[0097] [Chemistry 3]

[0098]

[0099] In the above general formula (c2-1), R c21 It is an alkyl group having 1 to 30 carbon atoms.

[0100] When the alkyl group has 1 to 30 carbon atoms, the effects of the present invention are likely to be enhanced.

[0101] From the viewpoint of making it easier to improve the effect of the present invention, R c21 The number of carbon atoms of the alkyl groups is each independently preferably 1 to 20, more preferably 4 to 16, and even more preferably 4 to 14.

[0102] As an optional R c21 Specific examples of the alkyl group which can be selected as R include c11 and R c12 The alkyl group is exemplified by the alkyl group of alkyl group. The alkyl group may be linear or branched.

[0103] In the above general formula (c2-1), nc21 is an integer of 1 to 5 independently.

[0104] From the viewpoint of making it easier to enhance the effect of the present invention, nc21 is each independently preferably 1 to 3, more preferably 1 to 2, and even more preferably 1.

[0105] The compound represented by the general formula (c2-1) may be used alone or in combination of two or more.

[0106] (Content ratio of component (C1) and component (C2))

[0107] In the lubricating oil composition of the present embodiment, when the amine antioxidant (C) contains a diphenylamine antioxidant (C1) and a naphthylamine antioxidant (C2), the content ratio [(C1) / (C2)] of the diphenylamine antioxidant (C1) to the naphthylamine antioxidant (C2) is preferably 0.10 to 9.00, more preferably 0.25 to 4.00, further preferably 0.50 to 2.00, and further preferably 0.75 to 1.25 in terms of mass ratio, from the viewpoint of more easily enhancing the effect of the present invention.

[0108] <Content ratio of component (B) to component (C)>

[0109] In the lubricating oil composition of the present embodiment, from the viewpoint of more easily enhancing the effects of the present invention, the content ratio [(B) / (C)] of the zinc dithiophosphate (B) to the amine antioxidant (C) is preferably 0.01 to 0.50, more preferably 0.05 to 0.30, and even more preferably 0.10 to 0.20 in terms of mass ratio.

[0110] <Phosphorus-free phenolic antioxidant (D)>

[0111] The lubricating oil composition of the present embodiment may further contain a non-phosphorus-containing phenolic antioxidant (D). However, when the lubricating oil composition of the present embodiment further contains a non-phosphorus-containing phenolic antioxidant (D), the content of the non-phosphorus-containing phenolic antioxidant (D) must be less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0112] The present inventors have studied the effectiveness of antioxidants using vegetable oil (A) as a target and have found that the oxidation stability of the lubricating oil composition is significantly reduced when the content of the phosphorus-free phenolic antioxidant (D) is 2.00 mass % or more.

[0113] Therefore, the amount of the non-phosphorus-containing phenolic antioxidant (D) is preferably small.

[0114] Specifically, the content of the non-phosphorus-containing phenolic antioxidant (D) is preferably less than 1.50 mass %, more preferably less than 1.00 mass %, further preferably less than 0.50 mass %, further preferably less than 0.10 mass %, further preferably less than 0.05 mass %, further preferably less than 0.01 mass %, based on the total amount of the lubricating oil composition. It is most preferred that the lubricating oil composition does not contain the non-phosphorus-containing phenolic antioxidant (D).

[0115] Examples of the phosphorus-free phenolic antioxidant (D) include phosphorus-free phenolic antioxidants having a phenol skeleton and being generally used as antioxidants for lubricating oil compositions. For example, the phosphorus-free phenolic antioxidant (D) includes not only compounds having a phenol skeleton and consisting only of carbon atoms, hydrogen atoms, and oxygen atoms, but also compounds having a phenol skeleton and having sulfur atoms in addition to carbon atoms, hydrogen atoms, and oxygen atoms (sulfur-containing phenol compounds), and the like.

[0116] Here, in the lubricating oil composition of the present embodiment, the content of the compound represented by the following general formula (d-1) as the phosphorus-free phenolic antioxidant (D) is particularly preferably small from the viewpoint of improving the oxidation stability of the lubricating oil composition.

[0117] [Chemistry 4]

[0118]

[0119] In the above general formula (d-1), R d1 It is an alkylene group having 1 to 5 carbon atoms.

[0120] Optional R d1 The number of carbon atoms in the alkylene group may be 1-4, 1-3, or 1-2.

[0121] Optional R d1 Specific examples of the alkylene group include straight-chain alkylene groups such as methylene, ethylene, n-propylene, n-butylene, and n-pentylene; and branched-chain alkylene groups such as isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, and neopentylene.

[0122] In the above general formula (d-1), R d2 It is an alkyl group having 1 to 25 carbon atoms.

[0123] Optional R d2 The alkyl group may have 2 to 20 carbon atoms, 4 to 15 carbon atoms, or 6 to 10 carbon atoms.

[0124] As an optional R d2 Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, etc. These may be linear or branched.

[0125] In the above general formula (d-1), R d3 and R d4 Each independently represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms.

[0126] As an optional R d3 and R d4 The alkyl group may be selected from the above R c1 and R c2 The alkyl group is the same as the alkyl group.

[0127] Among them, as an optional R d3 and R d4 The number of carbon atoms of the alkyl group may be 1 to 20, 1 to 10, or 1 to 6, independently of one another.

[0128] Here, the phosphorus-free phenolic antioxidant (D) may have a hindered phenol skeleton. d3 and R d4 The alkyl group may be a branched alkyl group, may be a branched alkyl group having 1 to 6 carbon atoms, or may be a tert-butyl group.

[0129] <Zinc dithiocarbamate (E)>

[0130] The lubricating oil composition of the present embodiment preferably further contains zinc dithiocarbamate (E). By making the lubricating oil composition further contain zinc dithiocarbamate (E), the oxidation stability of the lubricating oil composition can be further improved.

[0131] Preferred examples of the zinc dithiocarbamate (E) include compounds represented by the following general formula (e-1).

[0132] [Chemistry 5]

[0133]

[0134] In the general formula (e-1), R e1 ~R e4 Each independently represents a monovalent hydrocarbon group. As the monovalent hydrocarbon group, the following can be used: b1 ~R b4 Same group.

[0135] In addition, from the viewpoint of easily improving the oxidation stability of lubricating oil additives, R e1 ~R e4 The alkyl group is preferably a primary alkyl group or a secondary alkyl group or a combination thereof, more preferably a primary alkyl group.

[0136] In addition, R e1 ~R e4 The alkyl group preferably has 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 3 to 8 carbon atoms.

[0137] Specifically, primary zinc dithiocarbamate or secondary zinc dithiocarbamate or a combination thereof is more preferred, and primary zinc dithiocarbamate is more preferred.

[0138] From the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the content of zinc dithiocarbamate (E) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.08% by mass or more, based on the total amount of the lubricating oil composition. From the viewpoint of a balance between the amount of zinc dithiocarbamate (E) added and the effect of improving oxidation stability, the content of zinc dithiocarbamate (E) is preferably 1.00% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less, based on the total amount of the lubricating oil composition.

[0139] The zinc dithiocarbamate (E) may be used alone or in combination of two or more.

[0140] (Phosphorus-containing phenolic antioxidant (F))

[0141] The lubricating oil composition of the present embodiment preferably further contains a phosphorus-containing phenolic antioxidant (F). This is because the phosphorus-containing phenolic antioxidant (F) interacts with the amine-based antioxidant (C) to further enhance the antioxidant performance of the amine-based antioxidant (C). As the phosphorus-containing phenolic antioxidant (F), from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the following preferably includes compounds represented by the general formula (f-1).

[0142] [Chemistry 6]

[0143]

[0144] In the above general formula (f-1), R f1 , R f2 , R f3 and R f4 Each independently represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms.

[0145] As an optional R f1 , R f2 , R f3 and R f4 The alkyl group may be selected from the above R c1 and R c2 The alkyl group is the same as the alkyl group.

[0146] Among them, as an optional R f1 , R f2 , R f3 and R f4The number of carbon atoms of the alkyl groups is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6, each independently.

[0147] Here, the phosphorus-containing phenolic antioxidant (F) preferably has a hindered phenol skeleton. f1 and R f2 The alkyl group is preferably a branched alkyl group, more preferably a branched alkyl group having 1 to 6 carbon atoms, and further preferably a tert-butyl group.

[0148] In the above general formula (f-1), R f5 It is an alkylene group having 1 to 5 carbon atoms.

[0149] Optional R f5 The number of carbon atoms in the alkylene group is preferably 1 to 4, more preferably 1 to 3, further preferably 1 to 2, and further preferably 1.

[0150] As an optional R f5 Specific examples of the alkylene group include straight-chain alkylene groups such as methylene, ethylene, n-propylene, n-butylene, and n-pentylene; branched-chain alkylene groups such as isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, and neopentylene. Among these, methylene is preferred.

[0151] From the viewpoint of making it easier to improve the oxidation stability of the lubricating oil composition, the content of the phosphorus-containing phenolic antioxidant (F) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.08% by mass or more, based on the total amount of the lubricating oil composition. In addition, the content of the phosphorus-containing phenolic antioxidant (F) is preferably 1.00% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less, based on the total amount of the lubricating oil composition.

[0152] <Other ingredients>

[0153] The lubricating oil composition of the present embodiment may contain other components in addition to the components (A) to (F) within a range not impairing the effects of the present invention.

[0154] Examples of the other components include metal inactivators, rust inhibitors, and defoamers, etc. These may be used alone or in combination of two or more.

[0155] Furthermore, a detergent dispersant may be contained as the other component.

[0156] Furthermore, as the other component, one or more selected from mineral oils and synthetic oils may be contained.

[0157] (Metal Inerting Agent)

[0158] Examples of the metal inactivating agent include benzotriazole compounds, tolyltriazole compounds, thiadiazole compounds, imidazole compounds, and pyrimidine compounds.

[0159] When the lubricating oil composition of the present embodiment contains a metal inactivating agent, the content of the metal inactivating agent is preferably 0.01 to 5.0% by mass, more preferably 0.15 to 3.0% by mass, based on the total amount of the lubricating oil composition.

[0160] The metal inactivating agent may be used alone or in combination of two or more.

[0161] (Rust Inhibitor)

[0162] Examples of the rust inhibitor include sulfonic acid metal salts, organic phosphites, organic phosphates, organic phosphate metal salts, alkenyl succinic acid esters, and alkenyl succinic acid polyol esters.

[0163] The metal sulfonate is a metal salt of various sulfonic acids. Various sulfonic acids forming the metal sulfonate include aromatic petroleum sulfonic acids, alkyl sulfonic acids, aryl sulfonic acids, alkyl aryl sulfonic acids, and the like. More specifically, preferred examples include dodecylbenzenesulfonic acid, dilauryl cetylbenzenesulfonic acid, paraffin-substituted benzenesulfonic acid, polyolefin-substituted benzenesulfonic acid, polyisobutylene-substituted benzenesulfonic acid, naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, and the like. Among them, dinonylnaphthalenesulfonic acid is more preferred.

[0164] Preferred examples of the metal forming the sulfonic acid metal salt include sodium, magnesium, calcium, zinc, and barium. Among them, calcium and barium are preferred, and barium is more preferred from the viewpoint of rust prevention, storage stability, and availability.

[0165] When the lubricating oil composition of the present embodiment contains a rust inhibitor, the content of the rust inhibitor is preferably 0.01% by mass to 10.0% by mass, and more preferably 0.030% by mass to 5.00% by mass, based on the total amount of the lubricating oil composition.

[0166] The rust preventive agent may be used alone or in combination of two or more.

[0167] (Defoaming Agent)

[0168] Examples of the defoaming agent include silicone-based defoaming agents, fluorine-based defoaming agents such as fluorosilicone oil and fluoroalkyl ether, and polyacrylate-based defoaming agents.

[0169] When the lubricating oil composition of the present embodiment contains an antifoaming agent, the content of the antifoaming agent (amount of effective ingredient) is preferably 0.001% by mass to 0.50% by mass, more preferably 0.01% by mass to 0.30% by mass, based on the total amount of the lubricating oil composition.

[0170] The defoaming agent may be used alone or in combination of two or more.

[0171] (Detergent and dispersant)

[0172] Examples of the detergent dispersant include metal sulfonates, metal salicylates, metal phenates, and succinimide.

[0173] The content of the detergent-dispersant is generally 0.01% to 10% by mass, preferably 0.1% to 5% by mass, based on the total amount of the lubricating oil composition.

[0174] (Mineral oil, synthetic oil)

[0175] Examples of the mineral oil include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate base crude oil or cycloparaffinic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and mineral oils obtained by subjecting the distillates to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing and hydrorefining.

[0176] Examples of synthetic oils include polyolefins such as polybutene, 1-octene oligomers and 1-decene oligomers, and hydrogenated products thereof, and ethylene-α-olefin copolymers; isoparaffins; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenylene ether; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes; GTL base oils obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process (gas-to-liquids (GTL) wax), etc.

[0177] The mineral oil may be used alone or in combination of two or more. The synthetic oil may be used alone or in combination of two or more. In addition, one or more mineral oils and one or more synthetic oils may be used in combination.

[0178] When the lubricating oil composition of the present embodiment contains one or more selected from mineral oils and synthetic oils, the content thereof is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the vegetable oil (A), from the viewpoint of the gist of the present invention of introducing the concept of carbon neutrality.

[0179] [Physical properties of lubricating oil composition]

[0180] <40°C Kinematic Viscosity and Viscosity Index of Lubricating Oil Composition>

[0181] The 40° C. kinematic viscosity of the lubricating oil composition of the present embodiment is preferably 19.8 mm 2 / s~352mm 2 / s, more preferably 28.8 mm 2 / s~242mm2 / s, more preferably 28.8 mm 2 / s to 165 mm 2 / s.

[0182] <Acid value after ISOT test>

[0183] In the following examples of the lubricating oil composition of this embodiment, the acid value after the ISOT test is preferably 20.0 mgKOH / g or less, more preferably 15.0 mgKOH / g or less, and further preferably 10.0 mgKOH / g or less.

[0184] <Millipore value after ISOT test>

[0185] In the following examples of the lubricating oil composition of this embodiment, the Millipore value after the ISOT test is preferably 20 mg / 100 mL or less, more preferably 10 mg / 100 mL or less, and further preferably 5 mg / 100 mL or less.

[0186] <Carbon content after varnish plate coking test>

[0187] In the following examples of the lubricating oil composition of this embodiment, the carbon content after the varnish plate coking test is preferably 60 mg or less, more preferably 50 mg or less, and further preferably 40 mg or less.

[0188] <Zinc content>

[0189] In the lubricating oil composition of this embodiment, from the viewpoint of more easily improving the oxidation stability of the lubricating oil composition, the zinc content is preferably 0.01% by mass to 0.15% by mass, more preferably 0.02% by mass to 0.12% by mass, and further preferably 0.03% by mass to 0.10% by mass based on the total amount of the lubricating oil composition.

[0190] In this specification, the zinc content in the lubricating oil composition can be measured, for example, in accordance with JPI-5S-38-03.

[0191] <Molybdenum content>

[0192] In the lubricating oil composition of this embodiment, the molybdenum content is preferably less than 0.01% by mass, more preferably less than 0.001% by mass, and further preferably free of molybdenum based on the total amount of the lubricating oil composition.

[0193] In this specification, the molybdenum content in the lubricating oil composition can be measured, for example, in accordance with JPI-5S-38-03.

[0194] <Viscosity index improver>

[0195] In the lubricating oil composition of the present embodiment, the content of the viscosity index improver is preferably less than 0.01 mass %, more preferably less than 0.001 mass %, and further preferably contains no viscosity index improver, based on the total amount of the lubricating oil composition.

[0196] [Method for producing lubricating oil composition]

[0197] The method for producing the lubricating oil composition of the present embodiment is not particularly limited.

[0198] For example, the method for producing a lubricating oil composition according to the present embodiment includes the steps of mixing a vegetable oil (A), a zinc dithiophosphate (B), and an amine antioxidant (C) to prepare a lubricating oil composition,

[0199] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0200] The amount of the amine antioxidant (C) is 2.00% by mass or more based on the total amount of the lubricating oil composition.

[0201] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the amount of the non-phosphorus-containing phenolic antioxidant (D) contained is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0202] The production method may further include a step of blending one or more selected from zinc dithiocarbamate (E) and a phosphorus-containing phenolic antioxidant (F), as necessary.

[0203] In addition, this production method may further include a step of blending the above-mentioned other components as necessary.

[0204] The method of mixing the components is not particularly limited, and examples thereof include a method of mixing the components in the vegetable oil (A). In addition, the components may be mixed after being prepared into a solution (dispersion) by adding a diluent oil or the like. Preferably, after mixing the components, the components are stirred by a known method to be uniformly dispersed.

[0205] In addition, the preferred embodiments of the component (A), the component (B), the component (C), the component (D), the component (E), and the component (F) are as described above.

[0206] In addition, the amounts and proportions of component (A), component (B), component (C), component (D), component (E) and component (F) are preferably those corresponding to the preferred contents and proportions of the above-mentioned components (A), component (B), component (C), component (D), component (E) and component (F).

[0207] [Use of lubricating oil composition]

[0208] The lubricating oil composition according to the present embodiment is excellent in oxidation stability. Therefore, the lubricating oil composition according to the present embodiment is less likely to cause various problems such as sludge generation due to oxidation degradation, and the lubricating oil composition can be used stably for a long period of time.

[0209] Therefore, the lubricating oil composition of the present embodiment is used as, for example, a lubricating oil composition for a machine device requiring excellent oxidation stability. Specifically, it is preferably used as an industrial equipment oil. Examples of the industrial equipment oil include hydraulic oil, turbine oil, compressor oil, machine oil, or gear oil.

[0210] Among these, from the viewpoint of the oxidation stability of the lubricating oil composition according to the present embodiment, the lubricating oil composition according to the present embodiment can be suitably used as a rotary air compressor oil or a reciprocating air compressor oil, and can be particularly suitably used as a reciprocating air compressor oil.

[0211] Therefore, the lubricating oil composition according to the present embodiment provides the following methods of use (1) to (4).

[0212] (1) A method for using a lubricating oil composition, wherein the lubricating oil composition according to the present embodiment is used as an industrial equipment oil.

[0213] (2) A method for using a lubricating oil composition, wherein the lubricating oil composition according to the present embodiment is used as hydraulic oil, turbine oil, compressor oil, machine oil, or gear oil.

[0214] (3) A method of using a lubricating oil composition, wherein the lubricating oil composition according to the present embodiment is used as a rotary air compressor oil or a reciprocating air compressor oil.

[0215] (4) A method of using a lubricating oil composition, wherein the lubricating oil composition according to the present embodiment is used as a reciprocating air compressor oil.

[0216] [One embodiment of the present invention provided]

[0217] One embodiment of the present invention provides the following [1] to

[12] .

[0218] [1] A lubricating oil composition comprising a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C),

[0219] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0220] The content of the amine antioxidant (C) is 2.00 mass % or more based on the total amount of the lubricating oil composition.

[0221] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the content of the non-phosphorus-containing phenolic antioxidant (D) is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0222] [2] The lubricating oil composition according to [1] above, wherein the content of oleic acid among the fatty acids constituting the vegetable oil (A) is 65% by mass or more based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0223] [3] The lubricating oil composition according to [1] or [2] above, wherein the content of the zinc dithiophosphate (B) is 0.10% by mass or more based on the total amount of the lubricating oil composition.

[0224] [4] The lubricating oil composition according to any one of [1] to [3] above, wherein the amine antioxidant (C) contains a diphenylamine antioxidant (C1) and a naphthylamine antioxidant (C2).

[0225] [5] The lubricating oil composition according to [4] above, wherein the diphenylamine antioxidant (C1) is a compound represented by the following general formula (c1-1).

[0226] [Chemistry 7]

[0227]

[0228] [In the above general formula (c1-1), R c11 and R c12 Each independently represents an alkyl group having 1 to 30 carbon atoms. nc11 and nc12 each independently represent an integer of 1 to 5.]

[0229] [6] The lubricating oil composition according to [4] or [5] above, wherein the naphthylamine antioxidant (C2) is a compound represented by the following general formula (c2-1).

[0230] [Chemistry 8]

[0231]

[0232] [In the above general formula (c2-1), R c21 is an alkyl group having 1 to 30 carbon atoms. nc21 is an integer of 1 to 5.]

[0233] [7] The lubricating oil composition according to any one of [1] to [6] above, further comprising zinc dithiocarbamate (E).

[0234] [8] The lubricating oil composition according to any one of [1] to [7] above, further comprising a phosphorus-containing phenolic antioxidant (F).

[0235] [9] The lubricating oil composition according to any one of [1] to [8] above, further comprising one or more selected from the group consisting of a metal inactivating agent, a rust inhibitor and a defoaming agent.

[0236]

[10] The lubricating oil composition according to any one of [1] to [9] above, which is used as an industrial equipment oil.

[0237]

[11] A method for using the lubricating oil composition, comprising using the lubricating oil composition according to any one of [1] to [9] as an industrial equipment oil.

[0238]

[12] A method for producing a lubricating oil composition, comprising: mixing a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C) to prepare the lubricating oil composition;

[0239] Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A).

[0240] The amount of the amine antioxidant (C) is 2.00% by mass or more based on the total amount of the lubricating oil composition.

[0241] When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the amount of the non-phosphorus-containing phenolic antioxidant (D) contained is less than 2.00% by mass based on the total amount of the lubricating oil composition.

[0242] Example

[0243] The present invention will be specifically described by the following examples, but the present invention is not limited to the following examples.

[0244] [Measurement methods of various physical property values]

[0245] The various properties of the base oils used in the examples and comparative examples were measured in the following manner.

[0246] <40℃ Kinematic Viscosity and Viscosity Index>

[0247] The measurement and calculation were performed in accordance with JIS K2283:2000.

[0248] [Examples 1 to 3, Comparative Examples 1 to 5]

[0249] The following components were mixed to prepare lubricating oil compositions having the compositions shown in Table 1.

[0250] In addition, the numerical unit of the compounding composition in Table 1 is "mass %".

[0251] <Vegetable Oil (A)>

[0252] · Refined olive oil (Summit Oil Mill, product name: Olive Oil RS)

[0253] ·High oleic sunflower oil (Summit Oil Mill, product name: High oleic sunflower oil)

[0254] <Vegetable Oil (A')>

[0255] · Rapeseed refined oil (Summit Oil Mill, product name: Rapeseed refined oil)

[0256] ·Salad oil (Summit Oil Mill, product name: High Oleic Safflower Oil)

[0257] In Table 1, among the fatty acids constituting the vegetable oil (A) and the vegetable oil (A'), "other components" refer to fatty acids other than linoleic acid, linolenic acid, oleic acid and palmitic acid among the fatty acids constituting the vegetable oil.

[0258] <Zinc dithiophosphate (B)>

[0259] As zinc dithiophosphate (B), R in the general formula (b-1) is used. b1 ~R b4 It is an alkyl zinc dialkyl dithiophosphate.

[0260] The zinc dialkyl dithiophosphate is a compound mainly composed of a primary zinc dialkyl dithiophosphate. The alkyl group constituting the zinc dialkyl dithiophosphate mainly contains a primary alkyl group (hexyl group) having 6 carbon atoms, and partially contains an isobutyl group and an isopropyl group.

[0261] The zinc content of the zinc dialkyldithiophosphate was 8.5% by mass.

[0262] <Amine Antioxidant (C)>

[0263] ·"Dioctyldiphenylamine"

[0264] Dioctyldiphenylamine is R in the general formula (c1-1) c11 and R c12 It is an octyl group, nc11=nc12=1, and is a compound that meets the requirements of a diphenylamine antioxidant (C1).

[0265] · "4-tert-octylphenyl-1-naphthylamine"

[0266] p-tert-octylphenyl-1-naphthylamine is R in the general formula (c2-1) c21 It is a tert-octyl group, nc21=1, and is a compound that meets the requirements of the naphthylamine-based antioxidant (C2).

[0267] <Phosphorus-free phenolic antioxidant (D)>

[0268] · "3,5-bis(1,1-dimethylethyl)-4-hydroxy-alkyl phenylpropanoate"

[0269] Phenylpropionic acid-3,5-bis(1,1-dimethylethyl)-4-hydroxyalkyl ester is R in the general formula (d-1) d1 is an alkylene group having 2 carbon atoms, R d2 is an alkyl group with 8 carbon atoms, R d3 and R d4 A tert-butyl compound.

[0270] <Zinc dithiocarbamate (E)>

[0271] As zinc dithiocarbamate (E), diamyl zinc dithiocarbamate is used. Diamyl zinc dithiocarbamate is R e1 ~R e4 A compound which is a pentyl group (pentyl group, a primary alkyl group having 5 carbon atoms).

[0272] The zinc content in zinc diamyldithiocarbamate was 6.2% by mass.

[0273] <Phosphorus-containing phenolic antioxidant (F)>

[0274] · "Diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate"

[0275] 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid diethyl ester is R in the general formula (f-1) f1 and R f2 is tert-butyl, R f3 and R f4 Ethyl, R f5 A compound containing methylene.

[0276] <Other ingredients>

[0277] ·Carboxylic acid amide

[0278] ·Alkenyl succinic acid polyol ester

[0279] ·Barium dinonylnaphthalenesulfonate (50% dilution)

[0280] ·Organic silicon defoamer (100 times diluted)

[0281] <Evaluation>

[0282] (1) ISOT test

[0283] Copper and iron pieces were added as catalysts to the test oil (lubricating oil composition), and the ISOT test based on JIS K2514-1:2013 was carried out to force the test oil to deteriorate. The test temperature (oil temperature) was set to 120°C. In addition, the increase rate of the 40°C kinematic viscosity, the acid value (mgKOH / g), and the Millipore value (mg / 100mL) were measured for the test oil from the start of the ISOT test to 240 hours later.

[0284] Regarding the increase rate of 40°C kinematic viscosity, the 40°C kinematic viscosity of the lubricating oil composition after the ISOT test (post-test oil) was calculated as a percentage of how much the 40°C kinematic viscosity increased relative to the lubricating oil composition before the ISOT test (new oil). It can be said that the lower the increase rate of 40°C kinematic viscosity, the better the oxidation stability of the lubricating oil composition.

[0285] The acid value of the lubricating oil composition after the ISOT test was measured according to the indicator method of JIS K2501:2003.

[0286] It can be said that the lower the acid value after the ISOT test, the better the oxidation stability of the lubricating oil composition.

[0287] The Millipore value of the lubricating oil composition after the ISOT test was measured in accordance with ASTM D7873 using a membrane filter of Millipore Corporation having an average pore diameter of 1.0 μm.

[0288] It can be said that the lower the Millipore value, the better the oxidation stability of the lubricating oil composition.

[0289] (2) Coking test of painted board

[0290] According to Fed. Test Method Std. 791-3462, the test was conducted for 3 hours with a spray time of 15 seconds and a rest time of 45 seconds under the conditions of a painted plate temperature of 270°C and an oil temperature of 80°C. After the test, the amount of carbon attached to the painted plate (carbon attachment amount (mg)) was evaluated.

[0291] It can be said that the smaller the amount of carbon deposition, the better the oxidation stability.

[0292] The results are shown in Table 1.

[0293] The zinc content in the lubricating oil compositions of Examples 1 and 3 was 0.0657 mass % (based on the total amount of the lubricating oil composition, calculated value), and the zinc content in the lubricating oil composition of Example 2 was 0.0595 mass % (based on the total amount of the lubricating oil composition, calculated value).

[0294] [Table 1]

[0295]

[0296] The following conclusions can be drawn from the results shown in Table 1.

[0297] It can be seen that the lubricating oil compositions of Examples 1 to 3 have low kinematic viscosity increase rate, acid value and Millipore value after the ISOT test (120°C×240 hours), and carbon adhesion amount in the lacquered plate coking test (270°C), and are lubricating oil compositions excellent in oxidation stability.

[0298] In contrast, it can be seen that for the lubricating oil compositions of Comparative Examples 1 to 5, at least any one of the kinematic viscosity increase rate, acid value and Millipore value after the ISOT test (120°C × 240 hours), and the carbon adhesion amount in the lacquered plate coking test (270°C) of the lubricating oil compositions is high or cannot be measured, and they are lubricating oil compositions with poor oxidation stability.

Claims

1. A lubricating oil composition comprising a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C), Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A). The content of the amine antioxidant (C) is 2.00 mass % or more based on the total amount of the lubricating oil composition. When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the content of the non-phosphorus-containing phenolic antioxidant (D) is less than 2.00% by mass based on the total amount of the lubricating oil composition.

2. The lubricating oil composition according to claim 1, wherein Among the fatty acids constituting the vegetable oil (A), the content of oleic acid is 65% by mass or more based on the total amount of the constituent fatty acids in the vegetable oil (A).

3. The lubricating oil composition according to claim 1 or 2, wherein The content of the zinc dithiophosphate (B) is 0.10% by mass or more 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 amine antioxidant (C) contains a diphenylamine antioxidant (C1) and a naphthylamine antioxidant (C2).

5. The lubricating oil composition according to claim 4, wherein The diphenylamine antioxidant (C1) is a compound represented by the following general formula (c1-1): [Chemistry 1] In the above general formula (c1-1), R c11 and R c12 Each of them is independently an alkyl group having 1 to 30 carbon atoms, and nc11 and nc12 are each independently an integer of 1 to 5.

6. The lubricating oil composition according to claim 4 or 5, wherein The naphthylamine antioxidant (C2) is a compound represented by the following general formula (c2-1): [Chemistry 2] In the above general formula (c2-1), R c21 is an alkyl group having 1 to 30 carbon atoms, and nc21 is an integer of 1 to 5. 7 . The lubricating oil composition according to claim 1 , further comprising zinc dithiocarbamate (E). 8 . The lubricating oil composition according to claim 1 , further comprising a phosphorus-containing phenolic antioxidant (F). 9 . The lubricating oil composition according to claim 1 , further comprising at least one selected from the group consisting of a metal inactivating agent, a rust inhibitor and a defoaming agent. 10 . The lubricating oil composition according to claim 1 , which is used as an industrial equipment oil.

11. A method for using a lubricating oil composition, comprising using the lubricating oil composition according to any one of claims 1 to 9 as an industrial equipment oil.

12. A method for producing a lubricating oil composition, comprising: a step of mixing a vegetable oil (A), a zinc dithiophosphate (B) and an amine antioxidant (C) to prepare a lubricating oil composition, Among the fatty acids constituting the vegetable oil (A), the total content of linoleic acid and linolenic acid is less than 20% by mass based on the total amount of the constituent fatty acids in the vegetable oil (A). The amount of the amine antioxidant (C) blended is 2.00% by mass or more based on the total amount of the lubricating oil composition. When the lubricating oil composition further contains a non-phosphorus-containing phenolic antioxidant (D), the amount of the non-phosphorus-containing phenolic antioxidant (D) contained is less than 2.00% by mass based on the total amount of the lubricating oil composition.

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