JP2009197135A - Antioxidant composition for lubricant and lubricant composition comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antioxidant composition for a lubricant, which is excellent in antioxidant properties at high temperature and to provide a lubricant composition in which the antioxidant composition is blended. <P>SOLUTION: The antioxidant composition for the lubricant comprises: an (X) component being an amine compound represented by general formula (1) (wherein R<SP>1</SP>is a hydrogen atom or a methyl group; R<SP>2</SP>is a 6-20C aliphatic hydrocarbon group; A is a hydrocarbon group which may comprise one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom; m and n are each the number of 1-5); and a (Y) component being a phenol compound having one or more ester groups. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antioxidant composition for lubricating oil that can cope with higher temperatures than ever and a lubricating oil composition containing the same.

  Lubricating oil is used in various applications such as engine oil, drive system oil, turbine oil, and grease. In any of these applications, there are deterioration factors such as heat, attack of acidic substances, and long-term use, and it is essential to add an antioxidant to the lubricating oil in order to prevent deterioration.

  An amine compound, a phenol compound, or the like is used as an antioxidant for the lubricating oil (see, for example, Patent Documents 1 and 2). Amine-based antioxidants have excellent antioxidant performance at high temperatures, and phenolic antioxidants are said to have excellent antioxidant properties at low temperatures. Usually, both antioxidants are used in combination. In recent years, the performance of engines and drive trains has improved, and the number of cases where lubricants have been exposed to higher temperatures has increased. As a result, high-temperature oxidation stability has increased as a requirement for antioxidants. .

  As described above, antioxidants effective at high temperatures are amine-based, but at higher temperatures than before, there are problems such as decomposition of antioxidants and the required performance cannot be satisfied. In addition, diphenylamine-based antioxidants that are particularly frequently used in secondary amine compounds have sublimation properties, which cause sublimation at high temperatures and extremely deteriorate the oxidation stability of lubricating oils. It was. Furthermore, when the temperature is higher than ever, the phenolic antioxidants are also affected by decomposition and the like, and there has been an increasing demand for antioxidant compositions that can cope with such high temperatures.

  On the other hand, it is known that hindered amine compounds can also be used as antioxidants for lubricating oils (see, for example, Patent Document 3). However, these compounds have no difference in antioxidant performance in the temperature range considered so far compared to the above-mentioned amine compounds and phenol compounds, and since they are more expensive, they were not usually used in lubricating oils. . In addition, it has not been known that some of the hindered amine compounds exhibit an antioxidant effect at high temperatures.

Japanese Patent Laid-Open No. 6-200277 JP 7-33270 A JP 60-28496 A

  Therefore, the problem to be solved by the present invention is to provide an antioxidant composition for lubricating oils excellent in antioxidant properties at high temperatures and a lubricating oil composition containing them.

  Thus, the present inventors have intensively studied and found a composition that exhibits excellent antioxidation performance at high temperatures, leading to the present invention. That is, the present invention provides the following general formula (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and A represents one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom) And m and n each represent a number of 1 to 5.)
(X) component which is an amine compound represented, and (Y) component which is a phenol compound containing one or more ester groups, It is the antioxidant composition for lubricating oil characterized by the above-mentioned.

  The effect of the present invention is to provide an antioxidant composition for a lubricating oil excellent in antioxidant properties at high temperatures and a lubricating oil composition containing the same.

  The component (X) of the antioxidant composition for lubricating oil of the present invention is represented by the following general formula (1).

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and A represents one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom) And m and n each represent a number of 1 to 5.)
R ^{1 in the} general formula (1) represents a hydrogen atom or a methyl group, and is preferably a hydrogen atom because of its high antioxidant performance.

R ² in the general formula (1) represents an aliphatic hydrocarbon group having 6 to 20 carbon atoms. Examples of such aliphatic hydrocarbon groups include hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and the like. , Nonadecyl group, eicosyl group, isohexyl group, 2-ethylhexyl group, isooctyl group, isononyl group, isodecyl group, isoundecyl group, isododecyl group, isotridecyl group, isotetradecyl group, isopentadecyl group, isoheptadecyl group, isooctadecyl group, Alkyl groups such as isononadecyl group and isoeicosyl group; hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecyl group Group, to Putadeseniru group, octadecenyl group, nonadecenyl group, and an alkenyl group such as eicosenyl groups. These aliphatic hydrocarbon groups may be one type or a mixture of two or more types, and have good antioxidant performance, so are alkyl groups having 6 to 20 carbon atoms, preferably 7 to 18 alkyl groups, and 7 to 7 18 branched alkyl groups are more preferred. When the carbon number is less than 6 or exceeds 20, good antioxidant performance cannot be obtained.

  M and n of General formula (1) are numbers of 1-5, respectively. Although the sum of m and n is 2 to 10, the sum of m and n is preferably 3 to 6 because the solubility in lubricating oil is good and the antioxidant performance is also good, and the sum of m and n is More preferably, it is 3-6 and the value of m is 2-5. When the sum of m and n is greater than 10, the molecular weight becomes too large and the solubility in the lubricating oil decreases, and as a result, the performance as an antioxidant cannot be exhibited. Further, when m is 0, it does not function as an antioxidant, and when n is 0, the antioxidant performance at high temperature is inferior compared with the case where n is 1 or more.

  Next, A in the general formula (1) will be described. A may be a group derived from any compound as long as it is a hydrocarbon group which may contain one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom, but the component (X) represented by the general formula (1) Since A can be easily synthesized, A is preferably a group derived from an organic polyvalent carboxylic acid represented by the following general formula (3).

(A represents a hydrocarbon group which may contain one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom, and q represents a number of 2 to 10.)

  The polyvalent carboxylic acid represented by the general formula (3) is a polyvalent carboxylic acid containing 2 to 10 carboxyl groups. Examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, and succinic acid. Acid, glutaric acid, adipic acid, suberic acid, sebacic acid, decamethylene dicarboxylic acid, maleic acid, itaconic acid, acetylenedicarboxylic acid, bis (3,5-di-tert-butyl-4-hydroxybenzyl) malonic acid, thio Dipropionic acid, thioglycolic acid, methylenebisthioglycolic acid, iminodiacetic acid, tartaric acid, malic acid, thiomalic acid, dihydrotartaric acid, epoxysuccinic acid, 3,4-dioxythiophenedicarboxylic acid, 1,4-biscarboxyethylpiperazine , Phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalate Divalent carboxylic acids such as acid, 5-bicyclo (2,2,1) heptene-2,3-dicarboxylic acid, 5-bicyclo (2,2,2) heptene-2,3-dicarboxylic acid; propanetricarboxylic acid, Trivalent carboxylic acids such as butanetricarboxylic acid, butenetricarboxylic acid, nitrotriacetic acid, citric acid, triscarboxyethyl isocyanurate, trimellitic acid; butanetetracarboxylic acid, ethylenetetracarboxylic acid, ethylenediaminetetraacetic acid, pyromellitic acid, 1, Tetravalent carboxylic acids such as 3-bis (aminomethyl) cyclohexane-N, N, N ′, N′-tetraacetic acid; hexavalent carboxylic acids such as 1,6,7,8,9,14-tetradecanehexacarboxylic acid Polymer of carboxylic acid-containing monomers such as acrylic acid and methacrylic acid (oligomer having 2 to 10 carboxyl groups) Etc. Among these polyvalent carboxylic acids, those that do not contain an oxygen atom, a nitrogen atom, and a sulfur atom are preferable because they have excellent antioxidant properties, do not contain an oxygen atom, a nitrogen atom, and a sulfur atom, and do not contain a carboxyl group. What contains 3-6 pieces is more preferable. Moreover, as carbon number of A, 2-20 are preferable and 3-10 are more preferable. Examples of such preferable polyvalent carboxylic acid include propanetricarboxylic acid, butanetricarboxylic acid, trimellitic acid, butanetetracarboxylic acid, and ethylenetetracarboxylic acid.

The method for synthesizing the component (X) represented by the general formula (1) of the present invention is not particularly specified, and any method may be used as long as it is a known method. Esterification reaction of an organic polyvalent carboxylic acid represented by the general formula (3) with an alcohol represented by 4-hydroxy-2,2,6,6-tetramethylpiperidine and R ² OH, or a general formula (3 ) And an alcohol represented by 4-hydroxy-2,2,6,6-tetramethylpiperidine and an alcohol represented by R ² OH. Any method can be used for these reactions as long as it is a known method, and the ratio of m and n can be adjusted by the mixing ratio of alcohol.

  The (Y) component of the antioxidant composition for lubricating oil of the present invention is a phenol compound containing one or more ester groups. As such a compound, any compound having a phenolic hydroxyl group and an ester group in the molecule may be used. However, since the antioxidant performance and the stability at high temperature are good, the following general formula (2) The compounds represented are preferred.

(B represents a hydrocarbon group which may contain one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom, R ³ represents an alkylene group having 1 to 5 carbon atoms, and p represents a number of 1 to 5) R ⁴ and R ⁵ each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, but R ⁴ and R ⁵ do not simultaneously become a hydrogen atom.)

R ^{3 in the} general formula (2) represents an alkylene group having 1 to 5 carbon atoms. Examples of such an alkylene group include a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a pentylene group, and an isopentylene group. Among these alkylene groups, R ³ is preferably an ethylene group because it is inexpensive as a raw material.

R ⁴ and R ^{5 in} the general formula (2) each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, and an isopentyl group. Among these alkyl groups, a tertiary butyl group is preferable because of its good antioxidant performance. R ⁴ and R ⁵ do not simultaneously become hydrogen atoms, and it is preferable that both R ⁴ and R ⁵ are alkyl groups.

B in the general formula (2) may be derived from any compound as long as it represents a hydrocarbon group that may contain one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom. Since (Y) component represented by (5) can be easily synthesized, B is preferably derived from a 1 to 5 valent alcohol represented by B (OH) _P. As the alcohol represented by B (OH) _P, for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, iso-pentanol, secondary pentanol, neo-pentanol , Tertiary pentanol, hexanol, secondary hexanol, heptanol, secondary heptanol, octanol, 2-ethylhexanol, secondary octanol, nonanol, secondary nonanol, decanol, secondary decanol, undecanol, secondary undecanol, dodecanol, 2 Grade dodecanol, tridecanol, isotridecanol, secondary tridecanol, tetradecanol, secondary tetradecanol, hexadecanol, secondary hexadecanol, stearyl alcohol, Sostearyl alcohol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol, myricyl alcohol, lasserol, tetratriacontanol, 2-butyloctanol, 2-butyldecanol, 2-hexyloctanol, 2-hexyldecanol, 2-octyldecanol, 2-hexyldodecanol, 2-octyldodecanol, 2-decyltetradecanol, 2-dodecylhexadecanol, 2-hexadecyloctadecanol, 2-tetradecyloctadecanol, cyclopen Monohydric alcohols such as butanol, cyclohexanol, cycloheptanol, methylcyclopentanol, methylcyclohexanol, methylcycloheptanol, benzyl alcohol;

  Ethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, isoprene glycol (3-methyl-1,3-butane Diol), 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,2-octanediol, octanediol (2-ethyl-1,3-hexanediol), 2-butyl-2-ethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 1,2-decanediol, 1,2-dodecanediol, 1,2-tetradecanediol, 1 , 2-hexadecanediol, 1,2-octadecanediol, 1,12-octadecanediol, 2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, sorbide, 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4 -Divalent, such as octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, bis (hydroxymethyl) benzene, N-methyldiethanolamine, N-ethyldiethanolamine alcohol;

  Glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 2-methyl-1,2,3-propanetriol, 1,2,3-pentanetriol, 1,2,4-pentanetriol 1,3,5-pentanetriol, 2,3,4-pentanetriol, 2-methyl-2,3,4-butanetriol, trimethylolethane, 2,3,4-hexanetriol, 2-ethyl-1 , 2,3-butanetriol, trimethylolpropane, 4-propyl-3,4,5-heptanetriol, pentamethylglycerin (2,4-dimethyl-2,3,4-pentanetriol), triethanolamine, triethanolamine Trihydric alcohols such as isopropanolamine; pentaerythritol, 1,2,3,4-pentanetetrol, 2,3,4, -Hexanetetrol, 1,2,4,5-pentanetetrol, 1,3,4,5-hexanetetrol, diglycerin, ditrimethylolpropane, sorbitan, N, N, N ', N'-tetrakis ( Examples include tetrahydric alcohols such as 2-hydroxypropyl) ethylenediamine and N, N, N ′, N′-tetrakis (2-hydroxyethyl) ethylenediamine; pentavalent alcohols such as adonitol, arabitol, xylitol, and triglycerin.

  Among these, the monovalent alcohol is preferable, the monovalent alcohol is more preferable, the monovalent alcohol is preferable because the solubility in the lubricating oil is good, the handling is easy, and the antioxidant property is good. More preferred are aliphatic saturated alcohols. Moreover, as carbon number of B for the same reason, 3-20 are preferable, 5-18 are more preferable, and 6-13 are still more preferable.

  As a method for synthesizing the component (Y) represented by the general formula (2), any known method can be used. However, since it can be easily synthesized with an inexpensive raw material, the following general formula (4) Compound of

(R ³ represents an alkylene group having 1 to 5 carbon atoms, R ⁴ and R ⁵ each represent a hydrogen atom and an alkyl group having 1 to 5 carbon atoms, and M represents a hydrogen atom or a methyl group.)
And an esterification reaction or transesterification reaction with an alcohol represented by B (OH) _P above. As the reaction, a known esterification reaction or transesterification reaction can be used.

  In the lubricating oil composition of the present invention, the (X) component and the (Y) component of the antioxidant composition for lubricating oil of the present invention are each 0.1% by mass to 5% by mass with respect to the base oil. It is a blend. When the blending amount of the (X) component and the (Y) component is less than 0.1% by mass, the antioxidant may not function. When the blending amount exceeds 5% by mass, the effect corresponding to the addition amount cannot be obtained or sludge. May occur. Moreover, it is preferable to mix | blend so that ratio of (X) component and (Y) component may become (X) / (Y) = 2 / 8-8 / 2 (mass ratio). It is more preferable to mix | blend so that it may become 4 (mass ratio).

  Examples of the base oil that can be used include mineral oil, synthetic oil, and mixtures thereof. More specifically, poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, Synthetic oils such as alkylene glycol, polyphenyl ether, alkyl-substituted diphenyl ether, polyol ester, dibasic acid ester, carbonate ester, silicone oil, fluorinated oil, GTL, etc .; paraffinic mineral oil, naphthenic mineral oil or refined mineral oils obtained by refining them Etc. These base oils may be used alone or in a mixture. Among these base oils, the performance as a base oil is high and does not adversely affect machines such as engines. Therefore, poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, paraffin Mineral oil, naphthenic mineral oil, and GTL are preferable, and poly-α-olefin, paraffinic mineral oil, naphthenic mineral oil, and GTL are more preferable. Moreover, it is preferable to use a base oil having a viscosity index of 100 or more, and poly-α-olefin, GTL, and refined mineral oil having a viscosity index of 100 or more are more preferable.

A more preferable poly-α-olefin is a polymer having at least one selected from α-olefins having 8 to 20 carbon atoms and having a number average molecular weight of 5,000 to 1,000,000. The viscosity is 1 mm ² / s to ²⁰ mm ² / s. Further, as a more preferable ethylene-α-olefin copolymer, at least one structural unit selected from α-olefins having 8 to 20 carbon atoms is 50 to 99% by mass, and a structural unit of ethylene is 1% by mass to 50% by mass. % in an amount of, a polymer having a number average molecular weight from 5,000 to 1,000,000, kinematic viscosity at 100 ° C. is of ^{1mm 2} / ^s~20mm 2 / s.

Mineral oil is refined by hydrorefining, solvent removal, solvent extraction, solvent dewaxing, catalytic dewaxing, hydrocracking, sulfuric acid washing, clay treatment, etc., and kinematic viscosity at 100 ° C. is 1 mm ² / s The thing of 20 mm < ² > / s is still more preferable.

Kinematic viscosity of the base oil is not particularly limited, the kinematic viscosity at 100 ° C., preferably from ^{2mm 2} / ^s~8mm 2 / s, more preferably 2.5mm ² / s~6mm ² / s, particularly preferably it is preferably adjusted to 3mm ² /s~4.5mm ² / s. If the kinematic viscosity at 100 ° C. of the base oil exceeds 8 mm ² / s, the low-temperature viscosity characteristics may be deteriorated. If the kinematic viscosity is less than 2 mm ² / s, the oil film formation at the lubrication point is insufficient. Therefore, the lubricity may be inferior or the evaporation loss of the base oil may increase.

  Further, as the engine oil, it is preferable to use a mineral oil or a synthetic oil having a viscosity index of 100 or more, preferably 110 or more, but 1 to 100 parts by mass of a synthetic oil is blended with respect to 100 parts by mass of the mineral oil. May be. The synthetic oil is preferably a poly-α-olefin or an ethylene-α-olefin copolymer, more preferably a poly-α-olefin.

  The lubricating oil composition of the present invention can also be used as a grease. As the grease, a thickener may be added to the lubricating oil composition of the present invention, and the component (X) of the antioxidant composition for lubricating oil of the present invention is added to the base grease (base oil + thickener). And (Y) component may be blended so as to be 0.1% by mass to 5% by mass, respectively. As the base grease that can be used, a thickener may be added to the base oils listed above. Preferred base oils include poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, paraffinic mineral oil, naphthenic mineral oil, GTL, and poly-α-olefin, paraffinic mineral oil, Naphthenic mineral oil and GTL are more preferable.

  Thickeners include soap thickeners such as aluminum, barium, calcium, lithium and sodium, complex soap thickeners such as complex lithium, complex calcium and complex aluminum, urea, diurea, triurea, tetraurea, arylurea, terephthalate. Organic non-soap thickeners such as taramate and inorganic non-soap thickeners such as bentonite and silica aerogel are used. These thickeners may be used alone or in combination of two or more. good. The amount of the thickener is not particularly limited, but is usually 3% by mass to 40% by mass, preferably 5% by mass to 20% by mass with respect to the base grease composed of the base oil and the thickener.

  The lubricating oil composition of the present invention does not refuse the addition of known lubricating oil additives, and depending on the intended use, friction reducer, extreme pressure agent, oiliness improver, detergent, dispersant, viscosity index improvement An agent, a pour point depressant, a rust inhibitor, a corrosion inhibitor, an antifoaming agent, and the like may be added as long as the effects of the present invention are not impaired.

  Examples of the friction reducing agent include organic molybdenum compounds such as sulfurized oxymolybdenum dithiocarbamate and sulfurized oxymolybdenum dithiophosphate. A preferable blending amount of these friction reducing agents is 30 mass ppm to 2,000 mass ppm, more preferably 50 mass ppm to 1,000 mass ppm in terms of molybdenum content with respect to the base oil. However, since phosphorus atoms adversely affect the catalyst of the engine, it is preferable to use sulfurized oxymolybdenum dithiocarbamate rather than sulfurized oxymolybdenum dithiophosphate containing phosphorus atoms, and sulfurized oxysulfides having an alkyl group having 8 to 13 carbon atoms. The use of molybdenum dithiocarbamate is more preferred.

  Examples of extreme pressure agents include sulfur additives such as sulfurized fats and oils, olefin polysulfides, and dibenzyl sulfide; phosphorus compounds such as monooctyl phosphate, tributyl phosphate, triphenyl phosphite, tributyl phosphite, and thiophosphate A metal salt of thiophosphate, a metal salt of thiocarbamate, an acid phosphate metal salt, an organic metal compound such as zinc dithiophosphate, and the like. A preferable blending amount of these extreme pressure agents is 0.01% by mass to 2% by mass, and more preferably 0.05% by mass to 1% by mass with respect to the base oil. Zinc dithiophosphate also has a function as an antiwear agent and a function as an antioxidant.

  Examples of the oil improver include higher alcohols such as oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid and stearic acid; esters such as oleyl glycerol ester, stearyl glycerol ester and lauryl glycerol ester; lauryl amide and oleyl amide Amides such as stearylamide; amines such as laurylamine, oleylamine, stearylamine; ethers such as laurylglycerol ether and oleylglycerol ether. The preferable compounding quantity of these oiliness improvers is 0.1 mass%-5 mass% with respect to base oil, More preferably, it is 0.2 mass%-3 mass%.

  Examples of the detergent include sulfonates such as calcium, magnesium, and barium, phenates, salicylates, phosphates, and overbased salts thereof. Among these, overbased salts are preferable, and among the overbased salts, those having a TBN (total basic number) of 30 mgKOH / g to 500 mgKOH / g are more preferable. Furthermore, salicylate-based detergents having no phosphorus and sulfur atoms are preferred. The preferable compounding quantity of these detergents is 0.5 mass%-10 mass% with respect to base oil, More preferably, they are 1 mass%-8 mass%.

  Examples of the dispersant include succinimide, succinic ester, benzylamine, and boron-modified products thereof to which an alkyl group or alkenyl group having a weight average molecular weight of about 500 to 3,000 is added. The preferable compounding quantity of these dispersing agents is 0.5 mass%-10 mass% with respect to base oil, More preferably, they are 1 mass%-8 mass%.

  Examples of the viscosity index improver include poly (C1-18) alkyl methacrylate, (C1-18) alkyl acrylate / (C1-18) alkyl methacrylate copolymer, diethylaminoethyl methacrylate / (C1-18) alkyl methacrylate copolymer. Polymers, ethylene / (C1-18) alkyl methacrylate copolymers, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymers, styrene / maleic ester copolymers, styrene / isoprene hydrogenated copolymers, and the like. . Alternatively, a dispersion type or multifunctional viscosity index improver imparted with a dispersion performance may be used. The weight average molecular weight is about 10,000 to 1,500,000. A preferable blending amount of these viscosity index improvers is 0.1% by mass to 20% by mass with respect to the base oil. More preferably, it is 0.3 mass%-15 mass%.

  Examples of the pour point depressant include polyalkyl methacrylate, polyalkyl acrylate, polyalkyl styrene, polyvinyl acetate and the like, and the weight average molecular weight is 1,000 to 100,000. The preferable compounding quantity of these pour point depressants is 0.005 mass%-3 mass% with respect to base oil, More preferably, it is 0.01 mass%-2 mass%.

  Examples of the rust preventive include sodium nitrite, oxidized paraffin wax calcium salt, oxidized paraffin wax magnesium salt, beef tallow fatty acid alkali metal salt, alkaline earth metal salt or amine salt, alkenyl succinic acid or alkenyl succinic acid half ester (alkenyl The molecular weight of the group is about 100 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt and the like. The preferable compounding quantity of these rust preventive agents is 0.01 mass%-3 mass% with respect to base oil, More preferably, it is 0.02 mass%-2 mass%.

  Examples of the corrosion inhibitor include benzotriazole, benzimidazole, benzothiazole, tetraalkylthiuram disulfide and the like. A preferable blending amount of these corrosion inhibitors is 0.1% by mass to 3% by mass, and more preferably 0.02% by mass to 2% by mass with respect to the base oil.

  Examples of the antifoaming agent include polydimethyl silicone, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy / propoxylate, fatty acid ethoxy / propoxylate, sorbitan partial fatty acid ester and the like. The preferable compounding quantity of these antifoaming agents is 0.001 mass%-0.1 mass% with respect to base oil, More preferably, it is 0.001 mass%-0.01 mass%.

  The lubricating oil composition of the present invention can be used for any lubricating application, such as engine oil, gear oil, turbine oil, hydraulic oil, flame retardant hydraulic fluid, refrigerator oil, compressor oil, It can be used for lubricating oil such as vacuum pump oil, bearing oil, insulating oil, sliding surface oil, rock drill oil, metal working oil, plastic working oil, heat treatment oil, grease. Among these, it can be suitably used in engine oil and turbine oil where the operating environment is severe and the lubricating oil tends to be hot. Grease is suitable as a bearing grease for automobiles that are subject to large loads and are likely to become hot. Can be used for

Hereinafter, the present invention will be specifically described by way of examples. In the following examples and the like,% and ppm are based on mass unless otherwise specified.
The compounds A-1 to D-3 used in the experiment are described below.
<Amine compound>
A-1: Tris (2,2,6,6-tetramethyl-4-piperidyl) mono (isotridecyl) -1,2,3,4-butanetetracarboxylate A-2: Bis (1,2, 2,6,6-pentamethyl-4-piperidyl) -di (isotridecyl) -1,2,3,4-butanetetracarboxylate A-3: bis (2,2,6,6-tetramethyl-4- Piperidyl) ・ di (isotridecyl) -1,2,3,4-butanetetracarboxylate A-4: bis (2,2,6,6-tetramethyl-4-piperidyl) ・ mono (isotridecyl) trimellitate A -5: Bis (2,2,6,6-tetramethyl-4-piperidyl) di (octyl)
1,2,3,4-butanetetracarboxylate A-6: bis (2,2,6,6-tetramethyl-4-piperidyl) di (linear tridecyl) -1,2,3,4 Butanetetracarboxylate A-7: Bis (2,2,6,6-tetramethyl-4-piperidyl) di (oleyl)-
1,2,3,4-butanetetracarboxylate A-8: mono (2,2,6,6-tetramethyl-4-piperidyl) mono (isotridecyl) -sebacate B-1: p, p'- Dioctyldiphenylamine B-2: Tris (2,2,6,6-tetramethyl-4-piperidyl) -trimellitate B-3: Tetra (2,2,6,6-tetramethyl-4-piperidyl) -1,2 , 3, 4
-Butanetetracarboxylate B-4: bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate

<Phenol compound>
C-1: Octadecyl-3- (3,5-ditertiarybutyl-4-hydroxyphenol) propionate C-2: Decyl-3- (3,5-ditertiarybutyl-4-hydroxyphenol) propionate C- 3: Tetrakis- (methylene-3- (3 ′, 5′-ditertiarybutyl-4′-hydroxyphenyl) propionate) methane D-1: 2,6-ditertiarybutyl-p-cresol D-2: 1,3,5-trimethyl-2,4,6-tris (3,5-ditertiarybutyl-4-hydroxybenzyl) benzene D-3: d-α-tocophenol

An amine compound that can be used in the present invention, for example, Compound A-1, was synthesized as follows.
In a 1-liter four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube, 51.3 g (0.3 mol) of 1,2,2,6,6-pentamethyl-4-hydroxypiperidine , 15.8 g (0.1 mol) of isotridecanol, and 3.35 g (0.0118 mol) of tetraisopropoxytitanium in 125 g of an aromatic solvent (Idemitsu Petrochemical Co., Ltd., Ipsol), A methanol solution of 23.4 g (0.1 mol) of 1,2,3,4-butanetetracarboxylic acid was added dropwise at 175 ° C. over 3 hours, and further reacted for 1 hour, followed by dehydration under reduced pressure for 4 hours. After completion of the reaction, the mixture was cooled to 130 ° C., 1.27 g of water was added to deactivate the catalyst, further cooled to 80 ° C., and washed with 20 g of water three times. After the oil / water separation, the organic layer was heated to 175 ° C. under reduced pressure to dehydrate and remove the solvent to obtain Compound A-1.

A phenol compound that can be used in the present invention, for example, Compound C-1, was synthesized as follows.
To a 3-liter four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was added 1000 g of methyl 3- (3 ′, 5′-ditert-butyl-4′-hydroxyphenyl) propionate ( 3.42 mol), 923.4 g (3.42 mol) of octadecanol, 2.1 g (55 mmol) of lithium methoxide, and IP-1620 (produced by Idemitsu Petrochemical Co., Ltd., aliphatic hydrocarbon solvent) 400 g of boiling point 166 ° C. to 205 ° C.) and stirred for 8 hours at 100 ° C. to 190 ° C. while gradually reducing the pressure to 10 mmHg. Further, the solvent was removed at 210 ° C. under reduced pressure to 2 mmHg, and then cooled to 100 ° C. and neutralized by adding acetic acid. After dissolving by adding 800 g of toluene, it was washed with 100 g of water three times. Thereafter, toluene was removed by heating under reduced pressure to obtain Compound C-1.

Said compound was melt | dissolved so that it might become the composition of Table 1 and Table 2 with respect to base oil (the unit of the number in a table | surface is the mass%), and they were made into test oil. Incidentally, the base oil used was a kinematic viscosity 4.24 mm ² / s (100 ℃), 19.65mm ² / s (40 ° C.), a mineral oil-based high VI oil viscosity index = 126.

<Test method>
The test oil blended as shown in Tables 1 and 2 above was subjected to an oxidation degradation test by the method of <Oxidation degradation test-2> below. The results are shown in Table 3. In addition, after the same test oil was forcibly oxidized at a high temperature by the following <Oxidation degradation test-1> method, an oxidation degradation test was conducted by the method <Oxidation degradation test-2>. The impact was compared. The results are shown in Table 4.

<Oxidation degradation test-1>
In accordance with JIS K-2514 (lubricating oil-oxidation stability test method), 250 ml of the sample is placed in a glass container containing a copper plate and an iron plate as a catalyst, and the above test oil is stirred so that air is involved at 1300 rpm. The test oil was oxidized and deteriorated by heating at 180 ° C. for 24 hours.

<Oxidation degradation test-2>
5 g of each of the above test oils was put into a 100 ml autoclave containing a glass inner tube, and sealed with a lid to which a pressure sensor and an exhaust pipe were attached. The air in the autoclave was exhausted from the exhaust pipe using a vacuum pump, and oxygen was introduced instead. The interior of the autoclave was brought into a 100% oxygen atmosphere, and at the same time, the pressure was set to 101 kPa. The autoclave was placed in a constant temperature bath at 150 ° C. and the pressure was checked every 1 hour. As the oxidative degradation progresses, oxygen is consumed and the pressure decreases, so that the progress of the oxidative degradation can be determined from the decrease in pressure. The test was terminated when the pressure dropped below 100 kPa. The reason why the pressure at 0 hour is 150 kPa is that the pressure in the container is increased by thermal expansion due to heating at 150 ° C. The equipment used for the analysis is as follows.
Pressure gauge: AP-10S, AP-V80 (manufactured by Keyence Corporation)
Data collection device: NR-600 (manufactured by Keyence Corporation)

  From Table 3, although the antioxidant performance does not change much in the system using the hindered amine compound and the phenol compound together, the system using only the hindered amine compound and the system using the amine compound and the phenol compound commonly used as an antioxidant in general. Then, it turns out that the antioxidant performance is a little inferior.

On the other hand, when Table 4 which is a test result after oxidative deterioration at high temperature is seen, the antioxidant performance is extremely deteriorated in a system using a phenol compound which does not have an ester bond (Comparative Examples 2 to 4). Similarly, the system using the hindered amine compound having no alkyl group or alkenyl group bonded by an ester bond (Comparative Examples 5 to 8) also has deteriorated antioxidant performance. Further, the antioxidant performance is also deteriorated in a system not containing a phenol compound (Comparative Example 1) and a system using a commonly used amine compound (Comparative Example 5). In addition, it was confirmed that the amine compound used for the comparative example 5 sublimated by the test of the oxidation deterioration test-1.

Claims (5)

The following general formula (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and A represents one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom) And m and n each represent a number of 1 to 5.)
(X) component which is an amine compound represented, and (Y) component which is a phenol compound containing 1 or more ester groups, The antioxidant composition for lubricating oil characterized by the above-mentioned. The component (Y) is represented by the following general formula (2)

(B represents a hydrocarbon group which may contain one or more atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom, R ³ represents an alkylene group having 1 to 5 carbon atoms, and p represents a number of 1 to 5) R ⁴ and R ⁵ each represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, but R ⁴ and R ⁵ do not simultaneously become a hydrogen atom.)
The antioxidant composition for lubricating oil according to claim 1, wherein The antioxidant composition for lubricating oil according to claim 1 or 2, wherein R ^{1 in the} general formula (1) is a hydrogen atom.   The total number of m and n of General formula (1) is 3-6, The antioxidant composition for lubricating oils as described in any one of Claims 1-3 characterized by the above-mentioned.   A lubricating oil composition comprising (X) component and (Y) component according to any one of claims 1 to 4 in an amount of 0.1% by mass to 5% by mass with respect to a base oil, respectively. .