JP2007277122A - Novel indole compound and lube oil composition comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel indole compound that can suppress oxidative deterioration of various lube oil compositions over a long period of time and a lube oil composition comprising the same. <P>SOLUTION: The novel indole compound is represented by general formula (1), wherein R<SP>1</SP>-R<SP>4</SP>are each a hydrogen atom or a hydrocarbon group and R<SP>1</SP>-R<SP>4</SP>are not a hydrogen atom simultaneously. The lube oil composition comprises the novel indole compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel indole compound and a lubricating oil composition containing the same.

  If lubricating oil such as engine oil, drive system oil, metalworking oil, etc. is used for a long time, it will be oxidized and deteriorated due to the presence of oxygen, heat and acid gas in the atmosphere. As the oxidative deterioration progresses, these lubricating oils cannot exhibit their ability before the oxidative deterioration, so attempts have been made to delay the oxidative deterioration so that they can be used for as long as possible. The most common practice is to add an antioxidant to these lubricating oils.

  Various types of antioxidants for lubricating oils are used, but at present, phenolic antioxidants, amine antioxidants, and zinc dithiophosphate are mainly used. Although lubricating oils containing these antioxidants have a certain effect, the lubricating oils are required to be further improved in antioxidant performance due to recent environmental problems.

  Under these circumstances, the only way to improve the antioxidant performance of current lubricants is to increase the amount of antioxidant. However, phenolic antioxidants have high activity and are effective in preventing initial oxidation, but break relatively quickly, so even if the amount is increased, the life is not prolonged. On the other hand, amine-based antioxidants have low activity and are relatively difficult to break, so they are suitable for long-term use. However, when the amount of amine-based antioxidant added increases, sludge is generated. In addition, increasing the amount of zinc dithiophosphate will increase the phosphorus content in the lubricating oil. For example, when used in automobile engine oil, it will adversely affect the exhaust gas catalyst, and metal elements may be released outdoors. was there.

で示される化合物と、合計で６０重量％（質量％）以上含むスチレン化ジフェニルアミン系化合物からなる潤滑剤酸化防止剤が開示されている。 Therefore, amine antioxidants having a relatively large molecular weight and non-aromatic amine antioxidants have been proposed as novel antioxidants.
For example, Patent Document 1 discloses that

And a lubricant antioxidant comprising a styrenated diphenylamine compound containing 60% by weight (mass%) or more in total.

（式中、Ｒ^１及びＲ^２はアルキレン基を表わし、Ｒ^３は水素原子又は炭化水素基を表わし、ｍは１以上の数を表わし、ｎは１以上の数を表わす。）で表わされるポリアミン化合物からなる酸化防止性潤滑油添加剤が開示されている。 Patent Document 2 discloses the following general formula (1).

(Wherein R ¹ and R ² represent an alkylene group, R ³ represents a hydrogen atom or a hydrocarbon group, m represents a number of 1 or more, and n represents a number of 1 or more). An antioxidant lubricating oil additive comprising a compound is disclosed.

JP-A-9-53087 Patent Claim Japanese Patent Laid-Open No. 11-302678 Claims

  However, the amine-based antioxidant as disclosed in Patent Document 1 has the same ease of oxidation prevention as the current product, and has no effect in terms of long life. Moreover, the non-aromatic amine-based antioxidant as disclosed in Patent Document 2 has low activity, and the antioxidant effect is not always sufficient.

（式中、Ｒ^１〜Ｒ^４は、水素原子又はアルキル基を表わし、Ｒ^５及びＲ^６は、水素原子、アルキル基又はオキシアルキル基を表わすが、Ｒ^５及びＲ^６が同時に水素原子であることはない）で表わされる新規インドール化合物及びこれを含有する潤滑油組成物を既に提案している（特許願２００６−１５１２１号）。 In order to solve the above problems, the present inventors have the following general formula.

(Wherein R ^{1 to} R ⁴ represent a hydrogen atom or an alkyl group, R ⁵ and R ⁶ represent a hydrogen atom, an alkyl group, or an oxyalkyl group, but R ⁵ and R ⁶ are simultaneously a hydrogen atom. Have already been proposed (Patent Application No. 2006-15121).

  Accordingly, an object of the present invention is to provide a novel indole compound capable of suppressing oxidative deterioration of various lubricating oil compositions over a long period of time and a lubricating oil composition containing the same.

（式中、Ｒ^１〜Ｒ^４は、水素原子又は炭化水素基を表わすが、Ｒ^１〜Ｒ^４が同時に水素原子であることはない）
で表わされる新規インドール化合物に係る。
また、本発明は、上記新規インドール化合物を含有する潤滑油組成物に係る。 Thus, the present inventors have intensively studied, found a novel indole compound, and reached the present invention. That is, the present invention provides the following general formula (1)

(Wherein R ^{1 to} R ⁴ represent a hydrogen atom or a hydrocarbon group, but R ^{1 to} R ⁴ are not simultaneously a hydrogen atom)
It relates to a novel indole compound represented by:
The present invention also relates to a lubricating oil composition containing the novel indole compound.

  The effect of the present invention is to provide a novel indole compound that can suppress oxidative deterioration of a lubricating oil composition for a long period of time.

In the novel indole compound of the present invention represented by the general formula (1), R ^{1 to} R ⁴ are a hydrogen atom or a hydrocarbon group. Examples of the hydrocarbon group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, secondary butyl group, tertiary butyl group, pentyl group, isopentyl group, secondary pentyl group, neopentyl group, Tertiary pentyl group, hexyl group, secondary hexyl group, heptyl group, secondary heptyl group, octyl group, 2-ethylhexyl group, secondary octyl group, nonyl group, secondary nonyl group, decyl group, secondary decyl group, Undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, isotridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl, hexadecyl, secondary hexadecyl, stearyl, eicosyl, docosyl Group, tetracosyl group, triacontyl group, 2-butyloctyl group, 2-butyldecyl Group, 2-hexyloctyl group, 2-hexyldecyl group, 2-octyldecyl group, 2-hexyldecyl group, 2-octyldodecyl group, 2-decyltetradecyl group, 2-dodecylhexadecyl group, 2-hexadecyl group Alkyl groups such as octadecyl group, 2-tetradecyloctadecyl group, monomethyl branched-isostearyl group; vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, pentenyl group, isopentenyl group, hexenyl group, Alkenyl groups such as heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl; phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl Group, cinnamyl group, benzhydride Group, trityl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, Aryl groups such as styrenated phenyl group, p-cumylphenyl group, phenylphenyl group, benzylphenyl group, alpha-naphthyl group, beta-naphthyl group; cyclopentyl group, cyclohexyl group, cycloheptyl group, methylcyclopentyl group, methylcyclohexyl group, Cycloalkyl groups such as methylcycloheptyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, methylcyclopentenyl group, methylcyclohexenyl group, methylcycloheptenyl group, and cycloalkenyl groups. Nyl group is mentioned. Alternatively, a structure in which R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ are wound around a ring may be used.

  Among these hydrocarbon groups, an alkyl group or a cycloalkyl group having no double bond is preferable and an alkyl group is more preferable because it is difficult to deteriorate. Moreover, 1-18 are preferable, 1-12 are more preferable, and 1-8 are still more preferable from the balance of the solubility to a base oil, and an antioxidant effect. When the number of carbon atoms is greater than 18, the molecular weight increases, so the effect per molecular weight is reduced, and the amount added must be increased, which is economically disadvantageous, or the melting point is increased, so the solubility in the base oil is increased. It may get worse.

Furthermore, it is preferable that any two groups of R ^{1 to} R ⁴ are hydrocarbon groups and the remaining two groups are hydrogen atoms, and any one group is a hydrocarbon group and the remaining three groups. Is more preferably a hydrogen atom, most preferably R ² is a hydrocarbon group and the remaining groups are hydrogen atoms.

  The novel indole compound of the present invention may be produced by any raw material and reaction method, and may be synthesized using a known raw material and a known reaction method. As a production method, for example, after dropping an acidic catalyst such as acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid or the like into a mixed solution of alkylcyclohexanone and phenylhydrazine, the mixture is reacted at 50 to 150 ° C. for about 1 hour and then cooled. Can be obtained as a precipitate. Moreover, a highly purified thing can be obtained by wash | cleaning the obtained deposit with solvents, such as ethanol. Among the acidic catalysts, a sulfuric acid catalyst is preferably used because it is easy to handle and easy to purify.

  Next, the lubricating oil composition of the present invention comprises the novel indole compound of the present invention as described above, and is an engine oil, gear oil, turbine oil, hydraulic oil, flame retardant hydraulic oil, refrigeration. It can be used as lubricating oil such as machine oil, compressor oil, vacuum pump, 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 as an engine oil or a turbine oil having a severe use environment.

  The lubricating base oil that can be used in the lubricating oil composition of the present invention is not particularly limited, and examples of general lubricating base oils conventionally used as lubricating base oils such as mineral oil, synthetic oil, and mixtures thereof Can do. More specifically, poly-alpha-olefin, ethylene-alpha-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, polyalkylene glycol, polyphenyl ether, alkyl-substituted diphenyl ether, polyol ester, dibasic acid ester, carbonate ester Synthetic oils such as silicone oils and fluorinated oils, paraffinic mineral oils, naphthenic mineral oils, or refined mineral oils obtained by purifying these can be used. Each of these base oils may be used alone or as a mixture.

  The content of the novel indole compound of the present invention relative to the total amount of the lubricating oil composition of the present invention is preferably 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, and further 0.1 to 3% by mass. preferable. When the content of the novel indole compound of the present invention is less than 0.01% by mass, the effect as an antioxidant may not be observed. When the content exceeds 5% by mass, an effect commensurate with the content is obtained. This is not preferable because there is a case where sludge is not generated.

  The antioxidant performance can be further improved by adding and blending the phenolic antioxidant to the lubricating oil composition of the present invention. Examples of phenolic antioxidants include 2,6-di-tert-butylphenol (hereinafter, tertiary butyl is abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol, 2, 6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 4,4′-methylenebis (2,6 -Di-t-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 4,4'-bis (2-methyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) 4,4′-isopropylidenebis (2,6-di-t-butylphenol), 2,2′-methylenebis (4-methyl-6-cyclohexylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,6-bis (2'-hydroxy-3'-t-butyl-5'-methylbenzyl) -4-methyl Phenol, 3-t-butyl-4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4 -Hydroxy-3,5-di-t-butylphenyl) stearyl propionate, 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate olei , Dodecyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, decyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4- Hydroxy-3,5-di-t-butylphenyl) octyl propionate, tetrakis {3- (4-hydroxy-3,5-di-t-butylphenyl) propionyloxymethyl} methane, 3- (4-hydroxy- 3,5-di-t-butylphenyl) propionic acid glycerin monoester, ester of 3- (4-hydroxy-3,5-di-t-butylphenyl) propionic acid and glycerin monooleyl ether, 3- (4 -Hydroxy-3,5-di-t-butylphenyl) propionic acid butylene glycol diester, 3- (4-hydroxy-3,5-di-t-butyl) Tilphenyl) propionic acid thiodiglycol diester, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 2,2′- Thiobis (4-methyl-6-tert-butylphenol), 2,6-di-tert-butyl-alpha-dimethylamino-p-cresol, 2,6-di-tert-butyl-4- (N, N′- Dimethylaminomethylphenol), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, tris {(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl-oxyethyl} isocyanurate, Tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4 Hydroxybenzyl) isocyanurate, bis {2-methyl-4- (alkylthiopropionyloxy) -5-tert-butylphenyl} sulfide, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6 -Dimethylbenzyl) isocyanurate, tetraphthaloyl-di (2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl disulfide), 6- (4-hydroxy-3,5-di-tert-butylanilino) -2,4-bis (octylthio) -1,3,5-triazine, 2,2-thio- {diethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl)} propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4-hydroxy -Benzyl-phosphate diester, bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, 3,9-bis [1,1-dimethyl-2- {beta- (3-tert-butyl- 4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5 -T-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis {3,3-bis- ( 4′-hydroxy-3′-t-butylphenyl) butyric acid} glycol ester and the like.

  The content of the phenolic antioxidant is preferably in the range of 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, and more preferably 0.1 to 3% by mass with respect to the total amount of the lubricating oil composition of the present invention. % Is more preferable. When the content of the phenolic antioxidant is less than 0.01% by mass, the effect of the phenolic antioxidant may not appear, and when the content exceeds 5% by mass, the effect corresponding to the addition amount is obtained. Since it may not be obtained or sludge may be generated, it is not preferable.

Furthermore, antioxidant performance can be further improved by blending the zinc dithiophosphate represented by the following general formula (2) into the lubricating oil composition of the present invention:

In the general formula (2), R ⁵ and R ⁶ represent a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, a cycloalkenyl group, and the like.

  Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, secondary pentyl, neopentyl, tertiary pentyl, hexyl, secondary hexyl, heptyl, 2 Secondary heptyl, octyl, 2-ethylhexyl, secondary octyl, nonyl, secondary nonyl, decyl, secondary decyl, undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, isotridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl , Hexadecyl, secondary hexadecyl, stearyl, eicosyl, docosyl, tetracosyl, triacontyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldecyl 2-octyldodecyl, 2-decyltetradecyl, 2-dodecyl-hexadecyl, 2-hexadecyl octadecyl, 2-tetradecyl-octadecyl, monomethyl branched - isostearyl and the like.

  Examples of the alkenyl group include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl and the like.

  As an aryl group, for example, phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, Nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, styrenated phenyl, p-cumylphenyl, phenylphenyl, benzylphenyl, alpha-naphthyl, beta-naphthyl group and the like can be mentioned.

  Examples of the cycloalkyl group and cycloalkenyl group include a cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl, methylcycloheptenyl group. Etc.

Among these hydrocarbon groups, R ⁵ and R ⁶ are preferably an alkyl group, more preferably a secondary alkyl group, and preferably have 3 to 14 carbon atoms and preferably 3 to 10 carbon atoms. More preferably, it is most preferably 3-8. R ⁵ and R ⁶ may be the same hydrocarbon group or different hydrocarbon groups.

  In the general formula (2), when a = 0, it is called neutral zinc dithiophosphate (neutral salt), and when a = 1/3, basic zinc dithiophosphate (basic salt) and being called. Since zinc dithiophosphate is a mixture of these neutral and basic salts, a is represented by a number from 0 to 1/3. The number of a varies depending on the production method of zinc dithiophosphate, but is preferably in the range of 0.08 to 0.3, more preferably 0.15 to 0.3, and most preferably 0.18 to 0.3. When a is larger than 0.3, the hydrolysis stability may be deteriorated. When a is smaller than 0.08, the wear resistance of the blended lubricating oil composition may be deteriorated.

  The content of zinc dithiophosphate is preferably in the range of 100 to 750 mass ppm, more preferably 100 to 600 mass ppm, still more preferably 100 to 500 mass ppm as the phosphorus content with respect to the total amount of the lubricating oil composition of the present invention. . When the content of zinc dithiophosphate is less than 100 ppm by mass, a synergistic effect with the novel indole compound of the present invention may not be obtained, and when it exceeds 750 ppm by mass, an effect commensurate with the addition amount may not be obtained. In addition, sludge may be generated, and when used for engine oil for automobiles, the exhaust gas catalyst may be adversely affected.

  The lubricating oil composition of the present invention does not refuse addition of other known lubricating oil additives, and other antioxidants, extreme pressure agents, antiwear agents, oiliness improvers, detergents depending on the intended use Further, a dispersant, a viscosity index improver, a pour point depressant, a rust inhibitor, a corrosion inhibitor, an antifoaming agent, and the like can be added as long as the effects of the present invention are not impaired.

  Other antioxidants include, for example, naphthylamine antioxidants, phenylenediamine antioxidants, diphenylamine antioxidants, amine antioxidants such as phenothiazine antioxidants, molybdenum dithiocarbamate, molybdenum dithiophosphate, A molybdenum amine complex etc. are mentioned. Some of these antioxidants have a plurality of effects such as extreme pressure agents, antiwear agents, and wear reducing agents, and the preferable blending amount is 0.001 with respect to the total amount of the lubricating oil composition. -3 mass%, More preferably, it is in the range of 0.01-1 mass%.

  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 An organic metal compound such as a thiophosphate metal salt, a thiocarbamic acid metal salt, and an acidic phosphate metal salt; A preferable blending amount of these extreme pressure agents is in the range of 0.01 to 1% by mass, more preferably 0.1 to 1% by mass, based on the total amount of the lubricating oil composition.

  Examples of the antiwear agent include phosphorus compounds such as phosphorus compounds such as molybdenum dithiophosphate, monooctyl phosphate, tributyl phosphate, triphenyl phosphite, tributyl phosphite, and thiophosphate. A preferable blending amount of these antiwear agents is in the range of 0.01 to 7% by mass, more preferably 0.05 to 5% by mass with respect to the total amount of the lubricating oil composition.

  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 preferred blending amount of these oiliness improvers is in the range of 0.1 to 5% by mass, more preferably 0.2 to 4% by mass, based on the total amount of the lubricating oil composition.

  Examples of the detergent include sulfonates such as calcium, magnesium, and barium, phenates, salicylates, phosphates, and overbased salts thereof. Of these, salicylate-based detergents having no phosphorus and sulfur atoms are preferred. The blending amount of these detergents is in the range of 0.5 to 10% by mass, more preferably 1 to 8% by mass with respect to the total amount of the lubricating oil composition.

  Examples of the dispersant include succinimide, succinic acid ester, benzylamine, and boron-modified products thereof to which an alkyl group or alkenyl group having a weight average molecular weight of about 700 to 3000, preferably 1000 to 2500 is added. . The preferable compounding amount of these dispersants is in the range of 0.5 to 10% by mass, more preferably 1 to 8% by mass with respect to the total amount of the lubricating oil composition.

  Examples of the viscosity index improver include poly (C1-C18) alkyl methacrylate, (C1-C18) alkyl acrylate / (C1-C18) alkyl methacrylate copolymer, diethylamino methacrylate / (C1-C18) alkyl methacrylate copolymer. , Ethylene / (C1-C18) alkyl methacrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymer, styrene / maleic acid ester copolymer, styrene / isoprene hydrogenated copolymer, 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, preferably about 20,000 to 1,000,000. A preferable blending amount of these viscosity index improvers is 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to the total amount of the lubricating oil composition.

  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, preferably 3,000 to 80,000. is there. A preferable blending amount of these pour point depressants is in the range of 0.005 to 3% by mass, more preferably 0.01 to 2% by mass with respect to the total amount of the lubricating oil composition.

  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 100 to 300, preferably about 150 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt and the like. The preferable compounding quantity of these rust preventives is 0.01-3 mass% with respect to lubricating oil composition whole quantity, More preferably, it exists in the range of 0.02-1 mass%.

  Examples of the corrosion inhibitor include benzotriazole, benzimidazole, benzothiazole, tetraalkylthiuram disulfide and the like. The preferable compounding amount of these corrosion inhibitors is in the range of 0.01 to 3% by mass, more preferably 0.02 to 1% by mass, based on the total amount of the lubricating oil composition.

  Examples of the antifoaming agent include polydimethyl silicone, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy / propoxylate, aliphatic ethoxy / propoxylate, sorbitan partial fatty acid ester, and the like. . The preferred blending amount of these antifoaming agents is in the range of 0.001 to 0.1% by mass, more preferably 0.001 to 0.05% by mass, based on the total amount of the lubricating oil composition.

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.
<Production Example 1>
10.8 g (0.1 mol) of phenylhydrazine and 15.4 g (0.1 mol) of 4-t-butylcyclohexanone were charged into a 100 ml flask equipped with a nitrogen introduction tube, a reflux tube, a stirrer, and a thermometer. To this, 367.5 g (0.75 mol) of 20 mass% sulfuric acid was added at room temperature, and then reacted by heating at 90 to 100 ° C. for 2 hours under reflux. After completion of the reaction, the reaction mixture was cooled to room temperature, and the precipitated suspended matter was collected by filtration and washed with ethanol. Then, it vacuum-dried and ethanol was removed and yellow powder was obtained as a reaction product. The yield of the obtained reaction product was 21.2 g. This reaction product is an indole compound (additive A) represented by the following (3) based on proton nuclear magnetic resonance spectrum [equipment used: JNM-LA400 (JEOL Datum Co., Ltd.)] and elemental analysis. confirmed. In addition, the result of a proton nuclear magnetic resonance spectrum is shown in FIG.

<Production Example 2>
The same reaction and purification were carried out using the same raw materials and reaction apparatus as in Production Example 1 except that 4-methylcyclohexanone was used instead of 4-t-butylcyclohexanone. The obtained reaction product was a yellow powder and was confirmed to be an indole compound (additive B) represented by the following (4) from proton nuclear magnetic resonance spectrum and elemental analysis.

<Production Example 3>
The same reaction and purification were performed using the same raw materials and reaction apparatus as in Production Example 1 except that 2-t-butylcyclohexanone was used instead of 4-t-butylcyclohexanone. The obtained reaction product was a yellow powder and was confirmed to be an indole compound (additive C) represented by the following (5) from proton nuclear magnetic resonance spectrum and elemental analysis.

<Production Example 4>
The same reaction and purification were performed using the same raw materials and reaction apparatus as in Production Example 1 except that 4-tridecylphenylhydrazine was used instead of 4-t-butylcyclohexanone. The obtained reaction product was a yellow powder and was confirmed to be an indole compound (additive D) represented by the following (6) from proton nuclear magnetic resonance spectrum and elemental analysis.

<Production Example 5>
The same reaction and purification were carried out using the same raw materials and reaction apparatus as in Production Example 1 except that 2,4-dioctylcyclohexanone was used instead of 4-t-butylcyclohexanone. The obtained reaction product was a yellow powder and was confirmed to be an indole compound (additive E) represented by the following (7) from proton nuclear magnetic resonance spectrum and elemental analysis.

  A lubricity test was carried out using the indole compounds of the formulas (3) to (7) produced in Production Examples 1 to 5 and the following additives F to I.

Additive F

Additive G

Additive H

Additive I
Zinc dithiophosphate [in the general formula (2), R ⁵ and R ⁶ = hexyl group, a = 0.2]

<Oxidation degradation test-1>
After adding the additives A to I to the base oil as shown in Table 1, stirring and dispersing / dissolving, add the base oil containing the additive to a 100 ml autoclave containing a glass inner tube. 5 g of each was put 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 reason why the pressure at 0 hour is 130 kPa is that the pressure in the container is increased by thermal expansion due to heating at 150 ° C.
The equipment, conditions of use, and properties of the base oil used in the analysis are as follows:
Base oil: Kinematic viscosity 4.24 mm ² / sec (100 ° C.), 19.65 mm ² / sec (40 ° C.), Viscosity index = 126 Mineral oil gauge Advanced VI oil pressure gauge: AP-10S, AP-V80 (Keyence Corporation) Made)
Data collection device: NR-600 (manufactured by Keyence Corporation)

＊（）内で表わされる添加剤の量は、組成物全体に対するそれぞれの添加剤の質量％。
＊比較例６は添加剤未添加で、基油のみで測定。

* The amount of additive represented in parentheses is the mass% of each additive relative to the total composition.
* Comparative Example 6 was measured with only the base oil without additives.

<Oxidation degradation test-2>
3. Gasoline engine oil is blended in the following composition, and JIS K 2514-1993 “Lubricating oil—Oxidation stability test method” 4. The oxidation stability of the blended gasoline engine oil was examined according to the ISOT test specified in 1. In the test, 250 ml of a sample was put into a glass container containing a copper plate and an iron plate as a catalyst, and the test oil was oxidatively deteriorated by heating at 165.5 ° C. for 168 hours while stirring so as to entrain air at 1300 rpm. From this result, the increase in the total acid value (the value obtained by subtracting the total acid value before deterioration from the total acid value after deterioration) was determined. The smaller the increase in total acid value, the higher the oxidation stability. The composition of the gasoline engine oil and the test results are shown in Table 2:

Base oil: mineral oil meter high VI oil with kinematic viscosity 4.24 mm ² / sec (100 ° C), 19.65 mm ² / sec (40 ° C), viscosity index = 126

  The lubricating oil composition containing the novel indole compound of the present invention includes engine oil, gear oil, turbine oil, hydraulic oil, flame retardant hydraulic oil, refrigerator oil, compressor oil, vacuum pump oil, bearing oil, insulating oil, soot It can be used as lubricating oil such as dynamic surface oil, rock drill oil, metal working oil, plastic working oil, heat treatment oil, grease oil.

1 is a diagram showing a proton nuclear magnetic resonance spectrum of a reaction product obtained in Example 1. FIG.

Claims (6)

The following general formula (1)

(Wherein R ^{1 to} R ⁴ represent a hydrogen atom or a hydrocarbon group, but R ^{1 to} R ⁴ are not simultaneously a hydrogen atom)
A novel indole compound represented by: The novel indole compound according to claim 1, wherein any one of R ^{1 to} R ⁴ is a hydrocarbon group.   A lubricating oil composition comprising the novel indole compound according to claim 1 or 2.   The lubricating oil composition according to claim 3, further comprising a phenolic antioxidant.   The lubricating oil composition according to claim 3 or 4, further comprising zinc dithiophosphate.   Furthermore, antioxidants (excluding phenolic antioxidants and zinc dithiophosphates), extreme pressure agents, antiwear agents, oiliness improvers, detergents, dispersants, viscosity index improvers, pour point depressants, The lubricating oil composition according to any one of claims 3 to 5, comprising one or more lubricating oil additives selected from the group consisting of rusting agents, corrosion inhibitors and antifoaming agents.

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