JP5406886B2 - Lubricating oil composition and hydraulic fluid - Google Patents

Description

  The present invention relates to a lubricating oil composition.

  Recently, the hydraulic operation system has become more sophisticated, and the case where the flow rate and direction of the hydraulic system are controlled by a valve such as a spool valve in order to perform high speed and high precision control. More cases are attached. The performance of such spool valves and servo valves is greatly reduced when sludge is generated in the hydraulic fluid. At the same time as wear, there is a strong demand for sludge-less hydraulic fluid that does not generate sludge.

  On the other hand, due to the revision of the Energy Conservation Law, energy reduction is an indispensable item in factories designated as energy management designated factories, and it is necessary to set a numerical target every year and execute energy conservation. As a part of such energy saving, reduction of power consumption of an operating motor in a hydraulic actuator widely used in a factory is an important issue. Therefore, the hydraulic fluid is required to improve its characteristics from the viewpoint of energy saving.

  Under such a background, development of a new hydraulic fluid is underway in order to meet the above demand. For example, conventionally, zinc antiwear agents such as zinc dithiophosphate (ZnDTP) have been widely used as antiwear agents for hydraulic fluids, but the use of zinc antiwear agents can cause sludge. In addition, the wear prevention effect due to the use of ZnDTP or the like is due to the formation of a hard coating such as iron phosphate on the metal surface. The formation of the coating increases the friction coefficient of the sliding part, so that the viewpoint of energy saving Is not preferable. Thus, various attempts have been made to improve the characteristics of hydraulic fluids without using zinc-based antiwear agents. For example, in Patent Document 1 below, in order to improve oxidation stability and lubrication performance under high pressure, an oil-based agent such as a complete ester or partial ester of a polyhydric alcohol, or a fatty acid amide, an amine-based antioxidant, A hydraulic fluid blended with a predetermined base oil together with a phenolic antioxidant and a phosphate ester is disclosed.

Japanese Patent Laid-Open No. 09-111277

  However, even with the above-described conventional hydraulic fluids, it is very difficult to achieve all of friction characteristics, wear resistance, sludge suppression and precipitation prevention at a high level in a well-balanced manner. In particular, the polyhydric alcohol ester described in Patent Document 1 is not necessarily sufficient in terms of the effect of improving friction characteristics. Moreover, when the blending amount of the polyhydric alcohol ester described in Patent Document 1 is increased in order to improve the friction characteristics, characteristics such as wear resistance, sludge suppression, and precipitation prevention properties of the hydraulic fluid may be impaired. is there.

  The present invention has been made in view of such circumstances, and a lubricating oil composition capable of achieving all of friction characteristics, wear resistance, sludge suppression, and precipitation prevention properties at a high level in a well-balanced manner. The purpose is to provide.

  As a result of diligent research to achieve the above-mentioned object, the inventors of the present invention, when adding a complete ester of a polyhydric alcohol and a fatty acid to a lubricating oil, make the composition of the constituent fatty acid of the ester satisfy a specific condition. As a result, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

  That is, the lubricating oil composition of the present invention is a complete ester of at least one base oil selected from mineral oil, fat and synthetic oil, polyhydric alcohol and fatty acid, and the constituent fatty acid has 1 to 4 carbon atoms. And an ester containing both a short-chain fatty acid and a C10-24 long-chain fatty acid.

  In the lubricating oil composition of the present invention, a short chain fatty acid having 1 to 4 carbon atoms and a long chain fatty acid having 10 to 24 carbon atoms are used in combination as a fatty acid constituting a complete ester of a polyhydric alcohol and a fatty acid. By setting the ratio of saturated fatty acid in the fatty acid to 60 mol% or more, the friction reducing effect of the complete ester can be exhibited to the maximum. Solubility can be improved sufficiently.

  Further, in the lubricating oil composition of the present invention, it is not necessary to excessively contain a polyhydric alcohol ester in order to obtain the above effects, so that the wear resistance, sludge suppression and precipitation prevention properties are maintained at a high level. be able to.

  Therefore, according to the present invention, it is possible to realize a lubricating oil composition that can achieve all of friction characteristics, wear resistance, sludge suppression, and precipitation prevention properties at a high level in a well-balanced manner. Further, by using the lubricating oil composition of the present invention as a hydraulic fluid, it is possible to improve the reliability and save energy of the hydraulic operation system.

  According to the present invention, it is possible to achieve all of friction characteristics, wear resistance, sludge suppression, and precipitation prevention in a balanced manner at a high level, which is useful for improving the reliability of a hydraulic system and saving energy. A lubricating oil composition is provided.

It is a figure explaining the arrangement | positioning and operation | movement of a disk and a ball | bowl in a SRV (micro reciprocating friction) test.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

    The lubricating oil composition of the present invention contains at least one selected from mineral oils, fats and oils as base oils.

  Among the base oils used in the present invention, as the mineral oil, the lubricating oil fraction obtained by subjecting the crude oil to atmospheric distillation and reduced pressure distillation, solvent removal, solvent extraction, hydrocracking, solvent dewaxing, Mention may be made of paraffinic or naphthenic mineral oils obtained by applying a suitable combination of one or more purification means such as catalytic dewaxing, hydrorefining, sulfuric acid washing and clay treatment. Examples of the fats and oils include beef tallow, lard, sunflower oil, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and hydrogenated products thereof.

  Synthetic oils include, for example, poly α-olefins (ethylene-propylene copolymer, polybutene, 1-octene oligomer, 1-decene oligomer, and hydrides thereof), alkylbenzene, alkylnaphthalene, monoester (butyl). Stearate, octyl laurate), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sepacate, etc.), polyester (trimellitic acid ester, etc.), polyol ester (Trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol Lumpur, polyphenyl ether, dialkyl diphenyl ether, phosphate ester (tricresyl phosphate, etc.), fluorine-containing compound (perfluoropolyether, fluorinated polyolefin and the like), silicone oils and the like. As a base oil of the lubricating oil composition of the present invention, the above base oils may be used alone or in combination of two or more.

  Among the above-mentioned base oils, it is preferable to use a mineral oil that has been subjected to hydrocracking treatment from the viewpoint of obtaining better sludge suppression.

The kinematic viscosity of the base oil used in the present invention is not particularly limited, but is usually kinematic viscosity at 40 ° C. from the viewpoints of excellent friction characteristics, cooling properties (heat removal properties), and low friction loss due to stirring resistance. Is preferably 5 to 1,000 mm ² / s, more preferably 7 to 500 mm ² / s, and still more preferably 10 to 200 mm ² / s. The viscosity index of the base oil is not particularly limited, but is preferably 80 to 500, and more preferably 100 to 300, from the viewpoint of suppressing oil film deterioration at high temperatures. Furthermore, although the pour point is also arbitrary, from the viewpoint of pump startability in winter, the pour point is usually preferably −5 ° C. or lower, more preferably −15 ° C. or lower.

  Moreover, the lubricating oil composition of the present invention is (A) a complete ester of a polyhydric alcohol and a fatty acid, and the constituent fatty acid is a short-chain fatty acid having 1 to 4 carbon atoms and a long-chain fatty acid having 10 to 24 carbon atoms. An ester containing both (hereinafter, simply referred to as “(A) polyhydric alcohol ester”) is contained.

  (A) As a polyhydric alcohol which comprises a polyhydric alcohol ester, a 2-10 valence normally, Preferably a 2-6 valent thing is used. Specific examples of the 2 to 10 polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 15 of propylene glycol). Monomer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3 -Dihydric alcohols such as propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2- Octamers such as diglycerin, triglyceride Phosphorus, tetraglycerin, etc.), trimethylolalkanes (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polyhydric alcohols; sugars such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and mixtures thereof That.

  Among these polyhydric alcohols, ethylene glycol, diethylene glycol, polyethylene glycol (ethylene glycol 3-10 mer), propylene glycol, dipropylene glycol, polypropylene glycol (propylene glycol 3-10 mer), 1,3- Propanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, glycerin, diglycerin, triglycerin, trimethylolalkane (trimethylolethane, trimethylolpropane, trimethylol Methylol butane and the like, and dimers and tetramers thereof, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol , 1,2,3,4 butane tetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, divalent to hexavalent polyhydric alcohols and mixtures thereof, such as mannitol and the like are preferable. Furthermore, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitan, and a mixture thereof are more preferable, and glycerin is particularly preferable in terms of superior friction characteristics.

  Moreover, (A) The fatty acid which comprises a polyhydric alcohol ester contains both a C1-C4 short chain fatty acid and a C10-C24 long chain fatty acid.

  Specific examples of short-chain fatty acids having 1 to 4 carbon atoms include saturated fatty acids such as formic acid, acetic acid, propionic acid, linear or branched butanoic acid, acrylic acid, linear or branched butenoic acid And unsaturated fatty acids such as acetic acid.

  Specific examples of the long chain fatty acid having 10 to 24 carbon atoms include linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched dodecanoic acid, direct Linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecanoic acid, direct Linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched henicosanoic acid, Saturated fatty acid such as linear or branched docosanoic acid, linear or branched tricosanoic acid, linear or branched tetracosanoic acid, linear or branched decenoic acid, linear or branched Undecenoic acid, linear or Branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear or branched pentadecenoic acid, linear or branched hexadecenoic acid, linear or Branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched nonadecenoic acid, linear or branched icosenoic acid, linear And unsaturated fatty acids such as linear or branched docosenoic acid, linear or branched tricosenoic acid, linear or branched tetracosenoic acid, etc. 12-18 long chain fatty acids are preferred.

  In addition, although the constituent fatty acid of (A) the polyhydric alcohol ester may further contain a fatty acid having 5 to 9 carbon atoms or a fatty acid having 25 or more carbon atoms, a fatty acid having 5 to 9 carbon atoms and a fatty acid having 25 or more carbon atoms can be used. The total ratio is preferably 5 mol% or less, more preferably 2 mol% or less, based on the total amount of constituent fatty acids. Furthermore, (A) the constituent fatty acid of the polyhydric alcohol ester is particularly preferably composed of only a short-chain fatty acid having 1 to 4 carbon atoms and a long-chain fatty acid having 10 to 24 carbon atoms.

  Moreover, the ratio of the said short chain fatty acid to the sum total of a C1-C4 short chain fatty acid and a C10-24 long chain fatty acid becomes like this. Preferably it is 50-80 mol%, More preferably, it is 60-75 mol%. More preferably, it is 65 to 70 mol%. When the proportion of the short chain fatty acid is less than 50 mol%, the solubility in the base oil tends to decrease. Moreover, when the ratio of the short chain fatty acid exceeds 80 mol%, the friction reducing effect tends to be reduced.

  In addition, in (A) the polyhydric alcohol ester, each of the short-chain fatty acid having 1 to 4 carbon atoms and the long-chain fatty acid having 10 to 24 carbon atoms may be either a saturated fatty acid or an unsaturated fatty acid, or saturated. A mixture of a fatty acid and an unsaturated fatty acid may be used, but the ratio of the saturated fatty acid in the total amount of the constituent fatty acids is preferably 60 mol% or more, more preferably 75 mol% or more, and still more preferably 90 mol% or more, Especially preferably, it is 95 mol% or more. In addition, when the ratio of the saturated fatty acid is less than 60 mol%, the friction reducing effect tends to be insufficient.

  The content of the (A) polyhydric alcohol ester in the lubricating oil composition of the present invention is arbitrary, but it is preferably 0.01% by mass or more, more preferably, based on the total amount of the composition from the viewpoint of excellent friction reduction effect. Is 0.05 mass% or more, more preferably 0.1 mass% or more. In addition, the content is preferably 10% by mass or less, more preferably 7.5% by mass or less, and further preferably 5% by mass or less, based on the total amount of the composition, from the viewpoint of precipitation prevention.

  The lubricating oil composition of the present invention may further contain an ester oily agent other than the above (A) polyhydric alcohol ester (hereinafter referred to as “(B) ester oily agent” for convenience).

  (B) The alcohol constituting the ester oily agent may be a monohydric alcohol or a polyhydric alcohol. Moreover, as carboxylic acid which comprises (B) ester oily agent, a monobasic acid or a polybasic acid may be sufficient.

  (B) As the monohydric alcohol constituting the ester oily agent, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. However, it may be branched, and may be saturated or unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, linear or branched pentanol, and linear Linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol, linear or branched Undecanol, linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched pentadecanol, linear or branched hexadecane Decanol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonadecanol, linear or branched icosa Lumpur, linear or branched Hen'ikosanoru, linear or branched Torikosanoru, such as linear or branched tetracosanol, and mixtures thereof.

  Moreover, as a polyhydric alcohol which comprises (B) ester oiliness agent, a 2-10 valence normally, Preferably a 2-6 valence thing is used. Specific examples of the 2 to 10 polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 15 of propylene glycol). Monomer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3 -Dihydric alcohols such as propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2- Octamers such as diglycerin, triglyceride Phosphorus, tetraglycerin, etc.), trimethylolalkanes (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polyhydric alcohols; sugars such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and mixtures thereof That.

  Among these polyhydric alcohols, ethylene glycol, diethylene glycol, polyethylene glycol (ethylene glycol 3-10 mer), propylene glycol, dipropylene glycol, polypropylene glycol (propylene glycol 3-10 mer), 1,3- Propanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, glycerin, diglycerin, triglycerin, trimethylolalkane (trimethylolethane, trimethylolpropane, trimethylol Methylol butane and the like, and dimers and tetramers thereof, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol , 1,2,3,4 butane tetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, divalent to hexavalent polyhydric alcohols and mixtures thereof, such as mannitol and the like are preferable. Furthermore, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitan, and a mixture thereof are more preferable because of their superior friction characteristics.

  The alcohol constituting the ester oily agent may be a monohydric alcohol or a polyhydric alcohol as described above, but is preferably a polyhydric alcohol from the viewpoint of superior friction characteristics.

  Of the acids constituting the ester oily agent, as the monobasic acid, a fatty acid having 1 to 24 carbon atoms is usually used, and the fatty acid may be linear or branched, and may not be saturated. It may be saturated. Specifically, for example, formic acid, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched Heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched Dodecanoic acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched Heptadecanoic acid, linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched Henicosanoic acid, linear or minute Docosanoic acid, linear or branched tricosanoic acid, saturated fatty acids such as linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched pentene Acid, linear or branched hexenoic acid, linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched nonenoic acid, linear or branched decene Acid, linear or branched undecenoic acid, linear or branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear or branched pentadecene Acid, linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched Nonadecenoic acid, linear or minute Unsaturated fatty acids such as linear icosenoic acid, linear or branched henicosenoic acid, linear or branched docosenoic acid, linear or branched tricosenoic acid, linear or branched tetracosenoic acid, And mixtures thereof.

  Examples of the polybasic acid include dibasic acid and trimellitic acid, and dibasic acid is preferable. The dibasic acid may be a chain dibasic acid or a cyclic dibasic acid. Further, in the case of a chain dibasic acid, it may be either linear or branched, and may be either saturated or unsaturated. The chain dibasic acid is preferably a chain dibasic acid having 2 to 16 carbon atoms. Specifically, for example, ethanedioic acid, propanedioic acid, linear or branched butanedioic acid, linear Or branched pentanedioic acid, linear or branched hexanedioic acid, linear or branched heptanedioic acid, linear or branched octanedioic acid, linear or branched nonane diacid Acid, linear or branched decanedioic acid, linear or branched undecanedioic acid, linear or branched dodecanedioic acid, linear or branched tridecanedioic acid, linear or Branched tetradecanedioic acid, linear or branched heptadecanedioic acid, linear or branched hexadecanedioic acid, linear or branched hexenedioic acid, linear or branched heptenedioic acid Linear or branched octene diacid, linear or branched nonene diacid, linear or branched Branched decenedioic acid, linear or branched undecenedioic acid, linear or branched dodecenedioic acid, linear or branched tridecenedioic acid, linear or branched tetradecenedioic acid And linear or branched heptacene diacid, linear or branched hexadecene diacid, and mixtures thereof. Examples of the cyclic dibasic acid include 1,2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and aromatic dicarboxylic acid. Among these, a chain dibasic acid is preferable from the viewpoint of stability.

  (B) The acid constituting the ester oily agent may be a monobasic acid or a polybasic acid as described above, but a monobasic acid is preferable from the viewpoint of frictional characteristics.

(B) The combination of the alcohol and the acid in the ester oily agent is arbitrary and not particularly limited, and examples thereof include esters by the following combinations (B-1) to (B-7).
(B-1) ester of monohydric alcohol and monobasic acid (B-2) partial ester of polyhydric alcohol and monobasic acid (B-3) ester of monohydric alcohol and polybasic acid (B-4) ) Esters of polyhydric alcohols and polybasic acids (B-5) Monohydric alcohols, mixtures of polyhydric alcohols and polybasic acids (B-6) Polyhydric alcohols and monobasic acids, polybasic acids Mixed ester (B-7) with monohydric alcohol, polyhydric alcohol and monobasic acid, polybasic acid.

  Each of the esters of (B-3) to (B-7) may be a complete ester in which all of the hydroxyl groups of the polyhydric alcohol or the carboxyl groups of the polybasic acid are esterified. It may be a partial ester remaining as a hydroxyl group or a carboxyl group.

  Among the esters of (B-1) to (B-7), a partial ester of (B-2) a polyhydric alcohol and a monobasic acid is preferable. Such an ester has a very high effect of improving the friction characteristics.

  The ester (B-2) is preferably a mixture of two or more partial esters having different degrees of esterification from the viewpoint of precipitation prevention, friction characteristics, wear resistance and rust resistance. Is more preferably a mixture of a partial ester of which is 1 and a partial ester of which the degree of esterification is 2 or more. The degree of esterification here means the number of ester bonds in one molecule. For example, when the polyhydric alcohol constituting the ester (B-2) is sorbitan, the partial ester having a degree of esterification of 1 is a sorbitan monoester, while the partial ester having a degree of esterification of 2 or more. Includes sorbitan diesters and sorbitan triesters.

  Furthermore, when the ester of (B-2) includes both a partial ester having an esterification degree of 1 and a partial ester having an esterification degree of 2 or more, the ester of the partial ester having a degree of esterification of 1 The ratio is preferably 10 to 70 mol%, more preferably 20 to 50 mol%, based on the total amount of both. Moreover, the ratio of the partial ester whose esterification degree is 2 or more is preferably 30 to 70 mol%, more preferably 50 to 80 mol%, based on the total amount of both.

  In addition, the monobasic acid constituting the ester of (B-2) may be either a linear fatty acid or a branched fatty acid, but is preferably a linear fatty acid from the viewpoint of frictional properties, and has anti-precipitation properties. From this point, branched fatty acids are preferred.

  In addition, the monobasic acid constituting the ester of (B-2) may be either a saturated fatty acid or an unsaturated fatty acid, but a saturated fatty acid is preferable from the viewpoint of friction characteristics and wear resistance, From the viewpoint of preventing precipitation, unsaturated fatty acids are preferred. Furthermore, when the monobasic acid contains both saturated fatty acid and unsaturated fatty acid, the ratio of the saturated fatty acid to the total of both is preferably 60 mol% or more from the viewpoint of friction characteristics (particularly reduction of the friction coefficient), More preferably, it is 75 mol% or more, More preferably, it is 90 mol% or more, More preferably, it is 95 mol% or more.

  Moreover, although carbon number of the monobasic acid which comprises the ester of the said (B-2) is not restrict | limited, From the point of precipitation prevention property, it is C1-C4, More preferably, it is C2-short-chain fatty acid and It is preferable to combine with a long chain fatty acid having 10 to 24 carbon atoms, more preferably 12 to 18 carbon atoms. Furthermore, when combining said short chain fatty acid and long chain fatty acid, the ratio of the short chain fatty acid to the sum total of both becomes like this. Preferably it is 50-80 mol%, More preferably, it is 60-75 mol%, More preferably, it is 65-65. 70 mol%.

Among the esters of the above (B-2), it is preferable to use the esters shown in the following (ii-1) to (ii-4) from the viewpoint that various properties such as friction properties and precipitation preventing properties can be achieved in a balanced manner.
(B-2-1) Monoester of polyhydric alcohol and unsaturated fatty acid (B-2-2) Partial ester of polyhydric alcohol and unsaturated fatty acid, the partial ester having a degree of esterification of 1 A partial ester of an ester (B-2-3) polyhydric alcohol and a branched saturated fatty acid containing both a partial ester having a degree of esterification of 2 or more and a ester having a degree of esterification of 1 An ester comprising both a partial ester having a degree of 2 or more.

  The ester (B-2-1) is preferable in that the friction characteristics and the precipitation preventing property can be achieved at a high level. The number of carbon atoms of the unsaturated fatty acid constituting the ester (B-2-1) is preferably 10 or more, more preferably 12 or more, and still more preferably 14 or more, from the viewpoint that frictional properties are further improved. In addition, the number of carbon atoms of the unsaturated fatty acid is preferably 28 or less, more preferably 26 or less, and still more preferably 24 or less, from the viewpoint of precipitation prevention. Examples of such esters include glycerin monooleate and sorbitan monooleate.

  Further, the ester (B-2-2) is preferable in that it can achieve all of friction characteristics, precipitation prevention, wear resistance, and rust prevention at a high level in a well-balanced manner. The polyhydric alcohol constituting the ester of (B-2-2) may be one kind or a mixture of two or more kinds. When the polyhydric alcohol contains a divalent alcohol, it is trivalent or more. It is necessary to further contain the polyhydric alcohol.

  In the ester (B-2-2), the ratio of the partial ester having an esterification degree of 1 is the total amount of the partial ester having an esterification degree of 1 and the partial ester having an esterification degree of 2 or more. As a reference | standard, Preferably it is 10-70 mol%, More preferably, it is 20-50 mol%. The proportion of the partial ester having an esterification degree of 2 or more is preferably 30 to 70 mol based on the total amount of the partial ester having an esterification degree of 1 and the partial ester having an esterification degree of 2 or more. %, More preferably 50 to 80 mol%. In addition, although the ester of (B-2-2) may further contain a complete ester, it achieves all of friction characteristics, precipitation prevention, wear resistance and rust prevention at a high level in a well-balanced manner. Is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total amount of the ester of (B-2-2), and (ii-2) It is particularly preferred that the esters of do not contain complete esters.

  Further, the ester (B-2-3) is preferable in that it can achieve all of friction characteristics, precipitation prevention, wear resistance, and rust prevention at a high level in a well-balanced manner. In addition, the polyhydric alcohol constituting the ester of (ii-4) may be one kind or a mixture of two or more kinds. However, when the polyhydric alcohol contains a divalent alcohol, a polyvalent alcohol having a valence of 3 or more. It is necessary to further contain a monohydric alcohol.

  In the ester (B-2-3), the ratio of the partial ester having an esterification degree of 1 is the total amount of the partial ester having an esterification degree of 1 and the partial ester having an esterification degree of 2 or more. As a reference | standard, Preferably it is 10-70 mol%, More preferably, it is 20-50 mol%. The proportion of the partial ester having an esterification degree of 2 or more is preferably 30 to 70 mol based on the total amount of the partial ester having an esterification degree of 1 and the partial ester having an esterification degree of 2 or more. %, More preferably 50 to 80 mol%. In addition, although the ester of (B-2-3) may further contain a complete ester, it achieves all of friction properties, precipitation prevention, wear resistance and rust prevention at a high level in a well-balanced manner. Is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total amount of the ester of (B-2-3), and more preferably (B-2-3). It is particularly preferred that the ester of 3) does not contain a complete ester.

  Among the esters of the above (B-2-1) to (B-2-3), the balance of friction characteristics, precipitation prevention and wear resistance is the best, and the rust prevention is excellent. The ester of B-2-2) is particularly preferred.

  In addition, the lubricating oil composition of the present invention has (C) an alcohol oil agent, (D) a carboxylic acid oil agent, (E) an ether oil agent, as long as the effects of the (A) polyhydric alcohol ester are not impaired. F) An amine oily agent and (G) an amide oily agent may further be contained.

  (C) Alcohol oily agents include the alcohols exemplified in the description of the above (A) polyhydric alcohol ester and (B) ester oily agent. The number of carbon atoms in the alcohol oil-based agent is preferably 6 or more, more preferably 8 or more, and most preferably 10 or more, from the viewpoint of improving the friction characteristics. Moreover, since there exists a possibility that it may precipitate easily when carbon number is too large, 24 or less are preferable, 20 or less are more preferable, and 18 or less are the most preferable.

  (D) The carboxylic acid oily agent may be a monobasic acid or a polybasic acid. Examples of such carboxylic acids include monobasic acids and polybasic acids exemplified in the description of the above (A) polyhydric alcohol ester and (B) ester oily agent. Among these, a monobasic acid is preferable from the viewpoint of improving the friction characteristics. In addition, the number of carbon atoms in the (D) carboxylic acid oil-based agent is preferably 6 or more, more preferably 8 or more, and most preferably 10 or more, from the viewpoint of improving the friction characteristics. Moreover, since there exists a possibility that it may precipitate easily when carbon number of a carboxylic acid oiliness agent is too large, 24 or less are preferable, 20 or less are more preferable, and 18 or less are the most preferable.

  Examples of (E) ether oily agents include etherified products of 3-6 valent aliphatic polyhydric alcohols, bimolecular condensates or trimolecular condensates of 3-6 valent aliphatic polyhydric alcohols, and the like. .

  Etherified products of 3 to 6-valent aliphatic polyhydric alcohols are represented by, for example, the following general formulas (1) to (6).

[Wherein R ^{1 to} R ²⁵ may be the same or different, and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms, an allyl group, an aralkyl group, — (R ^a O ) _N- R ^b (R ^a is an alkylene group having 2 to 6 carbon atoms, R ^b is an alkyl group having 1 to 20 carbon atoms, an allyl group, an aralkyl group, and n is an integer of 1 to 10) Indicates an ether residue. ]
Specific examples of the 3-6 valent aliphatic polyhydric alcohol include glycerin, trimethylolpropane, erythritol, pentaerythritol, arabitol, sorbitol, mannitol and the like. R ^{1 to} R ²⁵ in the general formulas (1) to (6) are methyl group, ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, Various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various heptadecyl groups, various octadecyl groups, phenyl groups, benzyl groups, etc. Is mentioned. The etherified product also includes a partially etherified product in which a part of R ^{1 to} R ²⁵ is a hydrogen atom.

  The etherified product of a bimolecular condensate or a trimolecular condensate of a 3-6 valent aliphatic polyhydric alcohol is the same or different condensate of the compounds represented by the general formulas (1) to (6). Is mentioned. For example, the bimolecular condensate and the etherified product of the trimolecular condensate represented by the general formula (1) are represented by the general formulas (7) and (8), respectively. Moreover, the etherified product of the alcohol bimolecular condensate and trimolecular condensate represented by the general formula (4) is represented by the general formulas (9) and (10), respectively.

[Wherein R ^{1 to} R ³ and R ^{11 to} R ¹³ have the same definition as R ^{1 to} R ³ in formula (1) and R ^{11 to} R ¹⁴ in formula (4), respectively. ]
Specific examples of bimolecular and trimolecular condensates of 3-6 valent aliphatic polyhydric alcohols include diglycerin, ditrimethylolpropane, dipentaerythritol, disorbitol, triglycerin, tritrimethylolpropane, tripentaerythritol. And trisorbitol.

  Specific examples of the ether oil agents represented by the general formulas (1) to (6) include glycerin trihexyl ether, glycerin dimethyl octyl triether, glycerin di (methyloxyisopropylene) dodecyl triether, Diphenyl octyl triether, di (phenyloxy isopropylene) dodecyl triether of glycerol, trihexyl ether of trimethylol propane, dimethyl octyl triether of trimethylol propane, di (methyloxy isopropylene) dodecyl triether of trimethylol propane, Pentaerythritol tetrahexyl ether, pentaerythritol trimethyloctyl tetraether, pentaerythritol tri (methyloxyisopropylene) dodecyltetra Ether, hexapropyl ether of sorbitol, tetramethyloctyl pentaether of sorbitol, hexa (methyloxyisopropylene) ether of sorbitol, tetrabutyl ether of diglycerin, dimethyldioctyl tetraether of diglycerin, tri (methyloxyisopropylene of diglycerin) ) Dodecyl tetraether, triglycerin pentaethyl ether, triglycerin trimethyldioctylpentaether, triglycerin tetra (methyloxyisopropylene) decylpentaether, ditrimethylolpropane tetrabutylether, ditrimethylolpropane dimethyldioctyltetraether, Tri (methyloxyisopropylene) dodecyltetraate of ditrimethylolpropane , Pentaethyl ether of tritrimethylolpropane, trimethyldioctylpentaether of tritrimethylolpropane, tetra (methyloxyisopropylene) decylpentaether of tritrimethylolpropane, hexapropylether of dipentaerythritol, pentamethyloctylhexaether of dipentaerythritol , Hexa (methyloxyisopropylene) ether of dipentaerythritol, octapropyl ether of tripentaerythritol, pentamethyloctyl hexaether of tripentaerythritol, hexa (methyloxyisopropylene) ether of tripentaerythritol, octamethyl of disorbitol Dioctyldecaether, Deca of disorbitol (methyloxyisopropylene) Examples include ether. Among these, diphenyl octyl triether of glycerin, di (methyloxyisopropylene) dodecyl triether of trimethylolpropane, tetrahexyl ether of pentaerythritol, hexapropyl ether of sorbitol, dimethyldioctyl tetraether of diglycerin, triglycerin Tetra (methyloxyisopropylene) decyl pentaether, hexapropyl ether of dipentaerythritol, and pentamethyloctyl hexaether of tripentaerythritol are preferred.

  (F) Examples of the amine oily agent include monoamines, polyamines, alkanolamines, etc. Among these, monoamines are preferable from the viewpoint of friction characteristics.

Specific examples of monoamines include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine (including all isomers), dipropylamine (including all isomers), Propylamine (including all isomers), monobutylamine (including all isomers), dibutylamine (including all isomers), tributylamine (including all isomers), monopentylamine (all including all isomers) Including isomers), dipentylamine (including all isomers), tripentylamine (including all isomers), monohexylamine (including all isomers), dihexylamine (including all isomers) ), Monoheptylamine (including all isomers), diheptylamine (including all isomers) ), Monooctylamine (including all isomers), dioctylamine (including all isomers), monononylamine (including all isomers), monodecylamine (including all isomers), monoundecyl (Including all isomers), monododecylamine (including all isomers), monotridecylamine (including all isomers), monotetradecylamine (including all isomers), monopentadecyl Amine (including all isomers), monohexadecylamine (including all isomers), monoheptadecylamine (including all isomers), monooctadecylamine (including all isomers), mononona Decylamine (including all isomers), monoicosylamine (including all isomers), monohenicosylamine (including all isomers), monodocosyl Min (including all isomers), monotricosylamine (including all isomers), dimethyl (ethyl) amine, dimethyl (propyl) amine (including all isomers), dimethyl (butyl) amine (all Isomers), dimethyl (pentyl) amine (including all isomers), dimethyl (hexyl) amine (including all isomers), dimethyl (heptyl) amine (including all isomers), dimethyl ( Octyl) amine (including all isomers), dimethyl (nonyl) amine (including all isomers), dimethyl (decyl) amine (including all isomers), dimethyl (undecyl) amine (all isomers) ), Dimethyl (dodecyl) amine (including all isomers), dimethyl (tridecyl) amine (including all isomers), dimethyl (tetradecyl) ) Amine (including all isomers), dimethyl (pentadecyl) amine (including all isomers), dimethyl (hexadecyl) amine (including all isomers), dimethyl (heptadecyl) amine (all isomers) ), Dimethyl (octadecyl) amine (including all isomers), dimethyl (nonadecyl) amine (including all isomers), dimethyl (icosyl) amine (including all isomers), dimethyl (henicosyl) Alkylamines such as amines (including all isomers), dimethyl (tricosyl) amine (including all isomers);
Monovinylamine, divinylamine, trivinylamine, monopropenylamine (including all isomers), dipropenylamine (including all isomers), tripropenylamine (including all isomers), monobutenylamine (Including all isomers), dibutenylamine (including all isomers), tributenylamine (including all isomers), monopentenylamine (including all isomers), dipentenylamine (all isomers) ), Tripentenylamine (including all isomers), monohexenylamine (including all isomers), dihexenylamine (including all isomers), monoheptenylamine (all isomers) ), Diheptenylamine (including all isomers), monooctenylamine (including all isomers), dioctenylamine (Including all isomers), monononenylamine (including all isomers), monodecenylamine (including all isomers), monoundecenyl (including all isomers), monododecenylamine (Including all isomers), monotridecenylamine (including all isomers), monotetradecenylamine (including all isomers), monopentadecenylamine (including all isomers), Monohexadecenylamine (including all isomers), monoheptadecenylamine (including all isomers), monooctadecenylamine (including all isomers), monononadecenylamine (all isomers) ), Monoicosenylamine (including all isomers), monohenicocenylamine (including all isomers), monodocosenylamine (including all isomers), Trichoderma cell (including all isomers) cycloalkenyl amines alkenyl amines, such as;
Dimethyl (vinyl) amine, dimethyl (propenyl) amine (including all isomers), dimethyl (butenyl) amine (including all isomers), dimethyl (pentenyl) amine (including all isomers), dimethyl ( Hexenyl) amine (including all isomers), dimethyl (heptenyl) amine (including all isomers), dimethyl (octenyl) amine (including all isomers), dimethyl (nonenyl) amine (all isomers) ), Dimethyl (decenyl) amine (including all isomers), dimethyl (undecenyl) amine (including all isomers), dimethyl (dodecenyl) amine (including all isomers), dimethyl (tridecenyl) Amine (including all isomers), dimethyl (tetradecenyl) amine (including all isomers), dimethyl (pen Decenyl) amine (including all isomers), dimethyl (hexadecenyl) amine (including all isomers), dimethyl (heptadecenyl) amine (including all isomers), dimethyl (octadecenyl) amine (all isomers) ), Dimethyl (nonadecenyl) amine (including all isomers), dimethyl (icosenyl) amine (including all isomers), dimethyl (henicosenyl) amine (including all isomers), dimethyl (tricosenyl) Monoamines having alkyl and alkenyl groups such as amines (including all isomers);
Monobenzylamine, (1-phenyltyl) amine, (2-phenylethyl) amine (also known as monophenethylamine), dibenzylamine, bis (1-phenethyl) amine, bis (2-phenylethylene) amine (also known as diphenethylamine) Aromatic substituted alkylamines such as
C5-C16 cycloalkylamines such as monocyclopentylamine, dicyclopentylamine, tricyclopentylamine, monocyclohexylamine, dicyclohexylamine, monocycloheptylamine, dicycloheptylamine;
Monoamines having an alkyl group and a cycloalkyl group, such as dimethyl (cyclopentyl) amine, dimethyl (cyclohexyl) amine, dimethyl (cycloheptyl) amine;
(Methylcyclopentyl) amine (including all substituted isomers), bis (methylcyclopentyl) amine (including all substituted isomers), (dimethylcyclopentyl) amine (including all substituted isomers), bis (dimethylcyclopentyl) ) Amine (including all substituted isomers), (ethylcyclopentyl) amine (including all substituted isomers), bis (ethylcyclopentyl) amine (including all substituted isomers), (methylethylcyclopentyl) amine ( All substituted isomers included), bis (methylethylcyclopentyl) amine (including all substituted isomers), (diethylcyclopentyl) amine (including all substituted isomers), (methylcyclohexyl) amine (all substituted isomers) Isomers), bis (methylcyclohexyl) amine (all substituted isomers) ), (Dimethylcyclohexyl) amine (including all substituted isomers), bis (dimethylcyclohexyl) amine (including all substituted isomers), (ethylcyclohexyl) amine (including all substituted isomers), bis (Ethylcyclohexyl) amine (including all substituted isomers), (Methylethylcyclohexyl) amine (including all substituted isomers), (Diethylcyclohexyl) amine (including all substituted isomers), (Methylcycloheptyl) ) Amine (including all substituted isomers), bis (methylcycloheptyl) amine (including all substituted isomers), (dimethylcycloheptyl) amine (including all substituted isomers), (ethylcycloheptylamine) (Including all substituted isomers), (methylethylcycloheptyl) amine (all substituted isomers) And alkyl cycloalkylamines such as (diethylcycloheptyl) amine (including all substituted isomers), etc. The monoamine also includes monoamines derived from fats and oils such as beef tallow amine. It is.

  Among the above monoamines, alkylamines, monoamines having alkyl groups and alkenyl groups, monoamines having alkyl groups and cycloalkyl groups, cycloalkylamines and alkylcycloalkylamines are particularly preferred from the viewpoint of friction characteristics, and alkylamines, alkylamines are preferred. Monoamines having a group and an alkenyl group are more preferred.

  Although there is no restriction | limiting in particular about carbon number of a monoamine, From the point of a friction characteristic, it is preferable that it is 8 or more, and it is more preferable that it is 12 or more. Moreover, it is preferable that it is 24 or less from the point of the solubility to base oil, and it is more preferable that it is 18 or less.

  Further, the number of hydrocarbon groups bonded to the nitrogen atom in the monoamine is not particularly limited, but it is preferably 1 or 2 and more preferably 1 from the viewpoint of friction characteristics.

  (G) As an amide oily agent, an amine compound containing only a fatty acid having 6 to 30 carbon atoms or an acid chloride thereof, ammonia, a hydrocarbon group having 1 to 8 carbon atoms or a hydroxyl group-containing hydrocarbon group in the molecule, etc. Examples include amides obtained by reacting nitrogen-containing compounds.

  The fatty acid here may be a linear fatty acid or a branched fatty acid, and may be a saturated fatty acid or an unsaturated fatty acid. The carbon number is 6-30, preferably 9-24.

  Specific examples of the fatty acid include heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, Saturated fatty acids such as icosanoic acid, henicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid, pentacosanoic acid, hexacosanoic acid, heptacosanoic acid, octacosanoic acid, nonacosanoic acid and triacontyl group (these saturated fatty acids may be linear or branched) ); Heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid (including oleic acid), nonadecenoic acid, icosenic acid, Henicosenoic acid Unsaturated fatty acids such as docosenoic acid, tricosenoic acid, tetracosenoic acid, pentacosenoic acid, hexacosenoic acid, heptacosenoic acid, octacosenoic acid, nonacenoic acid, triacontenoic acid (these unsaturated fatty acids may be linear or branched, The position of the heavy bond is also arbitrary); but the linear fatty acids derived from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, various fats and oils (coconut oil fatty acid etc.) A mixture of linear fatty acid and branched fatty acid synthesized by the oxo method or the like is preferably used.

  Specific examples of the nitrogen-containing compound to be reacted with the fatty acid include ammonia; monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine, monohexylamine, monoheptylamine, monooctylamine, dimethylamine, Alkylamines such as methylethylamine, diethylamine, methylpropylamine, ethylpropylamine, dipropylamine, methylbutylamine, ethylbutylamine, propylbutylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, etc. May be chain or branched); monomethanolamine, monoethanolamine, monopropanolamine, monobutanolamine, monopentanolamine, monohexene Noramine, monoheptanolamine, monooctanolamine, monononanolamine, dimethanolamine, methanolethanolamine, diethanolamine, methanolpropanolamine, ethanolpropanolamine, dipropanolamine, methanolbutanolamine, ethanolbutanolamine, propanolbutanolamine, di Examples thereof include alkanolamines such as butanolamine, dipentanolamine, dihexanolamine, diheptanolamine and dioctanolamine (the alkanol group may be linear or branched); and mixtures thereof.

  Specific examples of fatty acid amides include lauric acid amide, lauric acid diethanolamide, lauric acid monopropanolamide, myristic acid amide, myristic acid diethanolamide, myristic acid monopropanolamide, palmitic acid amide, palmitic acid diethanolamide, and palmitic acid. Acid monopropanolamide, stearic acid amide, stearic acid diethanolamide, stearic acid monopropanolamide, oleic acid amide, oleic acid diethanolamide, oleic acid monopropanolamide, coconut oil fatty acid amide, coconut oil fatty acid diethanolamide, coconut oil fatty acid mono Propanolamide, C12-13 synthetic mixed fatty acid amide, C12-13 synthetic mixed fatty acid diethanolamide, C12-13 synthetic blend Fatty acid mono-propanol amides, and mixtures thereof are particularly preferred.

  Among the above oil agents (B) to (G), (B) ester oil agents and (G) amide oil agents are particularly preferable from the viewpoint of friction characteristics.

  The content of the oiliness agents (B) to (G) in the lubricating oil composition of the present invention is not particularly limited as long as the effect of the (A) polyhydric alcohol ester is not impaired, but preferably based on the total amount of the composition. It is 0.01-1 mass%, More preferably, it is 0.05-0.5 mass%.

  Moreover, the lubricating oil composition of the present invention may further contain (H) a phosphorus-containing carboxylic acid. (H) The phosphorus-containing carboxylic acid compound is not particularly limited as long as it contains both a carboxyl group and a phosphorus atom in the same molecule. However, phosphorylated carboxylic acids are preferred from the standpoints of wear resistance and sludge suppression, or even frictional properties.

  Examples of the phosphorylated carboxylic acid include compounds represented by the following general formula (11).

[In Formula (11), R ²⁶ and R ²⁷ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and R ²⁸ represents an alkylene group having 1 to 20 carbon atoms. , R ²⁹ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and the carbon numbers X ¹ , X ² , X ³ and X ⁴ may be the same or different and each represents an oxygen atom or a sulfur atom. ]
In general formula (11), R ²⁶ and R ²⁷ each represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, an alkenyl group, a cycloalkyl group, a bicycloalkyl group, a tricycloalkyl group, an alkylcycloalkyl group, an alkylbicycloalkyl group, an alkyltricycloalkyl group, and a cycloalkylalkyl. Group, bicycloalkylalkyl group, tricycloalkylalkyl group, aryl group, alkylaryl group, arylalkyl group and the like. R ¹ and R ² may be bonded to form a divalent group represented by the following general formula (12). The two bonds of the divalent group are bonded to X ¹ and X ² , respectively.

[In Formula (12), R ³⁰ and R ³¹ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and both R ⁵ and R ⁶ are methyl groups. preferable. ]
The R ¹ and R ^2, Among these alkyl groups, cycloalkyl group, cycloalkylalkyl group, tricycloalkyl group, an aryl group, an alkylaryl group, the general formula and R ²⁶ and R ²⁷ are bonded (12 ) Is preferably a divalent group, and more preferably an alkyl group.

The alkyl group as R ²⁶ and R ²⁷ may be linear or branched. The alkyl group preferably has 1 to 18 carbon atoms. Specific examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, 2-ethylbutyl group, 1- Methylphenyl group, 1,3-dimethylbutyl group, 1,1,3,3-tetramethylbutyl group, 1-methylhexyl group, isoheptyl group, 1-methylheptyl group, 1,1,3-trimethylhexyl group and Examples include 1-methylundecyl group. Among these, a C3-C18 alkyl group is preferable and a C3-C8 alkyl group is more preferable.

Examples of the cycloalkyl group as R ²⁶ and R ²⁷ include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclododecyl group. Among these, a cycloalkyl group having 5 or 6 carbon atoms (cyclopentyl group and cyclohexyl group) is preferable, and a cyclohexyl group is particularly preferable.

The cycloalkylalkyl group as R ²⁶ and R ²⁷ is preferably a cycloalkylmethyl group, more preferably a cycloalkylmethyl group having 6 or 7 carbon atoms, and particularly preferably a cyclopentylmethyl group and a cyclohexylmethyl group.

As the bicycloalkylalkyl group as R ²⁶ and R ²⁷ , a bicycloalkylmethyl group is preferable, a bicycloalkylmethyl group having 9 to 11 carbon atoms is more preferable, and a decalinylmethyl group is particularly preferable.

The tricycloalkylalkyl group as R ²⁶ and R ²⁷ is preferably a tricycloalkylmethyl group, more preferably a tricycloalkylmethyl group having 9 to 15 carbon atoms, represented by the following formula (13) or (14). Particularly preferred are the groups

The aryl group and alkylaryl group as R ²⁶ and R ²⁷ are phenyl group, tolyl group, xylyl group, ethylphenyl group, vinylphenyl group, methylphenyl group, dimethylphenyl group, trimethylphenyl group, ethylphenyl group, isopropyl group. Examples thereof include a phenyl group, a tert-butylphenyl group, a di-tert-butylphenyl group, and a 2,6-di-tert-butyl-4-methylphenyl group. Among these, an aryl group having 6 to 15 carbon atoms and an alkylaryl group are preferable.

R ²⁸ represents an alkylene group having 1 to 20 carbon atoms. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 2 to 6, and further preferably 3 to 4. Moreover, as such an alkylene group, what is represented by following General formula (15) is preferable.

In the general formula (15), R ³² , R ³³ , R ³⁴ and R ³⁵ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and R ³² , R ³³ , R The total number of carbon atoms of ³⁴ and R ³⁵ is 6 or less. Preferably, R ³² , R ³³ , R ³⁴ and R ³⁵ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and R ³² , R ³³ , R ³⁴ and the total number of carbon atoms for R ³⁵ is 5 or less. More preferably, R ³² , R ³³ , R ³⁴ and R ³⁵ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 or 2 carbon atoms, and R ³² , R ³³ , R ³⁴ and R ³⁵ The total of ³⁵ carbon atoms is 4 or less. Particularly preferably, R ³² , R ³³ , R ³⁴ and R ³⁵ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms, and R ³² , R ³³ , R ³⁴ and R ³⁵ The total of ³⁵ carbon atoms is 3 or less. Most preferably, either R ³⁴ or R ³⁵ is a methyl group and the remaining three groups are hydrogen atoms.

Moreover, R < ²⁹ > in General formula (11) shows a hydrogen atom or a C1-C30 hydrocarbon group. Examples of the hydrocarbon group include the hydrocarbon groups exemplified in the description of R ²⁶ and R ²⁷ . From the viewpoint of wear resistance, R ²⁹ is preferably a hydrogen atom.

Moreover, X < ¹ >, X < ² >, X < ³ > and X < ⁴ > in General formula (11) may be same or different, and respectively show an oxygen atom or a sulfur atom. From the viewpoint of wear resistance, one or more of X ¹ , X ² , X ³ or X ⁴ are preferably sulfur atoms, more preferably two or more are sulfur atoms, and two are sulfur atoms. More preferably, the remaining two are oxygen atoms. In this case, it is arbitrary which of X ¹ , X ² , X ³ or X ⁴ is a sulfur atom, but X ¹ and X ² are oxygen atoms, and X ³ and X ⁴ are sulfur atoms. It is preferable.

  As mentioned above, although each group in General formula (11) was demonstrated, since it is more excellent in abrasion resistance and a friction characteristic, (beta) -dithio phosphorylated propionic acid represented by following General formula (16) is used preferably. Is done.

Wherein ^{(16), R 26, R} 27 represents the same definition as ^{R 26, R 27} each formula (11) ^{in, R 32, R 33, R} 34, R 35 is in each (5) The same definition contents as R ³² , R ³³ , R ³⁴ , and R ³⁵ are shown. ]
The content of the (H) phosphorus-containing carboxylic acid compound in the lubricating oil composition of the present invention is not particularly limited, but is preferably 0.001 to 1% by mass, more preferably 0.002 to 0.00%, based on the total amount of the composition. 5% by mass. When the content of the phosphorus-containing carboxylic acid compound is less than the lower limit value, the effect of improving the wear resistance and friction characteristics tends to be insufficient. On the other hand, when the content exceeds the upper limit value, the sludge inhibiting property tends to be lowered. In addition, among the phosphorylated carboxylic acids represented by general formula (11), the compound containing R ⁴ is a hydrogen atom (including β-dithiophosphorylated propionic acid represented by general formula (16)). The amount is preferably 0.001 to 0.1% by mass, more preferably 0.002 to 0.08% by mass, still more preferably 0.003 to 0.07% by mass, and still more preferably 0.004 to 0%. 0.06% by mass, particularly preferably 0.005 to 0.05% by mass. When the content is less than 0.001, the effect of improving wear resistance and friction characteristics tends to be insufficient. On the other hand, when the content exceeds 0.1% by mass, sludge suppression tends to be reduced.

  Moreover, the lubricating oil composition of the present invention comprises (I-1) a thiophosphate ester and (I-2) a phosphorus-based antiwear agent not containing sulfur as a constituent element in addition to the above (H) phosphorus-containing carboxylic acid compound. (Hereinafter, simply referred to as “(I-2) phosphorus-based antiwear agent”) and the like may further be contained.

  (I-1) Specific examples of the thiophosphate ester include tributyl phosphorothioate, tripentyl phosphorothionate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothioate, Trinonyl phosphorothioate, tridecyl phosphorothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothioate , Trihexadecyl phosphorothionate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphoroate Thionate, trixylenyl phosphorothioate, cresyl diphenyl phosphorothioate, xylenyl diphenyl phosphorothioate, tris (n-propylphenyl) phosphorothionate, tris (isopropylphenyl) phosphorothionate, tris (N-Butylphenyl) phosphorothionate, Tris (isobutylphenyl) phosphorothionate, Tris (s-butylphenyl) phosphorothionate, Tris (t-butylphenyl) phosphorothionate, and the like can be given.

  Among the thiophosphates described above, triphenyl phosphorothioate and tricresyl phosphorothionate are particularly preferable.

  The content of the component (I-1) in the lubricating oil composition of the present invention is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1.5% by mass or less, based on the total amount of the composition. is there. When the content exceeds 5% by mass, the thermal stability of the lubricating oil composition becomes insufficient, and the sludge inhibiting property tends to decrease. The content of the component (I-1) is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.05% by mass or more, based on the total amount of the composition. When the content is less than 0.005% by mass, the effect of improving the wear resistance tends to be insufficient.

  Examples of the (I-2) phosphorus wear inhibitor include phosphoric acid esters, acidic phosphoric acid esters, amine salts of acidic phosphoric acid esters, chlorinated phosphoric acid esters, phosphorous acid esters, and the like.

  Specific examples of phosphate esters include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl Phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and And xylenyl diphenyl phosphate.

  Specific examples of the acidic phosphate ester include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate , Monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid phosphate Dipentyl acid phosphate, dihexyl Ruacid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl phosphate, dipentadecyl phosphate Examples include dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, and dioleyl acid phosphate.

  Examples of the amine salt of acidic phosphate ester include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Examples include salts with amines such as dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine.

  Examples of the chlorinated phosphate ester include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, and polyoxyalkylene bis [di (chloroalkyl)] phosphate.

  As phosphites, dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl Phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite Phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite and the like can be mentioned.

  The content of the component (I-2) in the lubricating oil composition of the present invention is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and still more preferably 0.8%, based on the total amount of the composition. It is below mass%. When content exceeds the said upper limit, the thermal stability of a lubricating oil composition becomes inadequate, and it exists in the tendency for sludge suppression property to fall. The content of the component (I-2) is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.4% by mass or more, based on the total amount of the composition. When content is less than the said lower limit, it exists in the tendency for an abrasion-resistant improvement effect to become inadequate.

  Further, in the lubricating oil composition of the present invention, sulfur-based antiwear agents such as dihydrocarbyl polysulfide, sulfide ester, sulfide mineral oil, zinc dithiophosphate compound, zinc dithiocarbamate compound, molybdenum dithiophosphate, and molybdenum dithiocarbamate May further be contained.

  Dihydrocarbyl polysulfide is a sulfur compound generally called polysulfide or sulfurized olefin, and is preferably a compound represented by the following general formula (17).

R ³⁶ -S _x -R ³⁷ (17)
[Wherein, R ³⁶ and R ³⁷ may be the same or different, and each of them is a linear or branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 to 20 carbon atoms. Or an arylalkyl group having 6 to 20 carbon atoms, and x is an integer of 2 to 6, preferably 2 to 5. ]
Specific examples of the sulfur ester include animal and vegetable fats and oils such as beef tallow, pork tallow, fish tallow, rapeseed oil and soybean oil; unsaturated fatty acids (oleic acid, linoleic acid or fatty acids extracted from the above-mentioned animal and plant fats and the like) And an unsaturated fatty acid ester obtained by reacting various alcohols with each other; and a mixture thereof obtained by sulfiding by an arbitrary method.

  Sulfided mineral oil refers to one obtained by dissolving elemental sulfur in mineral oil. As the elemental sulfur, there are those in the form of lump, powder, molten liquid and the like.

  The zinc dithiophosphate compound, the zinc dithiocarbamate compound, the molybdenum dithiophosphate compound, and the molybdenum dithiocarbamate compound are represented by the following general formulas (18) to (21), respectively.

[Wherein R ^{38 to} R ⁵³ may be the same or different and each represents a hydrocarbon group having 1 or more carbon atoms, and Z represents an oxygen atom or a sulfur atom, respectively. ]
In addition, from the point of friction characteristics and sludge suppression, it is preferable to make content of the above-mentioned sulfur type antiwear agent as small as possible, and it is more preferable not to use a sulfur type antiwear agent.

  The friction coefficient is also used when the sulfur type antiwear agent is used in the presence of the component (A) according to the present invention or in the presence of the components (H), (I-1), (I-2) and the like. Therefore, the content of the sulfur-based antiwear agent is preferably 5% by mass or less, more preferably 1% by mass or less, based on the total amount of the composition. More preferably, it is 0.5% by mass or less, and most preferably no sulfur-based antiwear agent is contained.

  The lubricating oil composition of the present invention preferably further contains (J) a dispersion-type viscosity index improver. When the lubricating oil composition of the present invention contains (J) a dispersion type viscosity index improver, the water separation property is sufficiently maintained, and the wear resistance and sludge suppression property or further the friction property is at a high level. It can be achieved in a well-balanced manner and is suitable as a hydraulic fluid that may be mixed with water during use.

  (J) As the dispersion-type viscosity index improver, any compound used as a dispersion-type viscosity index improver for lubricating oil can be used. For example, a nitrogen-containing monomer having an ethylenically unsaturated bond is a copolymerization component. The copolymer containing as is preferable. More specifically, one or more monomers selected from compounds represented by the following general formula (22), (23) or (24) (hereinafter referred to as “monomer (J-1)”); The copolymer with the 1 type (s) or 2 or more types of monomer (henceforth "monomer (J-2)") chosen from the compound represented by the following general formula (25) or (26) is preferable.

[Wherein, R ⁵⁴ represents a hydrogen atom or a methyl group, and R ⁵⁵ represents an alkyl group having 1 to 18 carbon atoms. ]

[Wherein, R ⁵⁶ represents a hydrogen atom or a methyl group, and R ⁵⁷ represents a hydrocarbon group having 1 to 12 carbon atoms. ]

[Wherein Y ¹ and Y ² may be the same or different and each represents a hydrogen atom, an alkoxy group having 1 to 18 carbon atoms, or a monoalkylamino group having 1 to 18 carbon atoms. ]

[Wherein, R ⁵⁸ represents a hydrogen atom or a methyl group, R ⁵⁹ represents an alkylene group having 2 to 18 carbon atoms, a represents 0 or 1, and Y ³ represents 1 to 30 carbon atoms containing a nitrogen atom. An organic group of ]

[Wherein, R ¹⁷ represents a hydrogen atom or a methyl group, and Y ⁴ represents a C 1-30 organic group containing a nitrogen atom. ]
Specific examples of the alkyl group having 1 to 18 carbon atoms represented by R ⁵⁵ in the general formula (22) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, etc. alkyl groups (these alkyl groups may be linear or branched) Is mentioned.

Specific examples of the hydrocarbon group having 1 to 12 carbon atoms represented by R ⁵⁷ in the general formula (23) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, Alkyl groups such as octyl, nonyl, decyl, undecyl, dodecyl (these alkyl groups may be linear or branched); butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl Groups, decenyl groups, undecenyl groups, dodecenyl groups and the like (these alkenyl groups may be linear or branched); C5-C7 cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl Methylcyclopentyl group, dimethylcyclopentyl group, methylethylcyclopentyl group, diethylcyclopentyl group, methyl An alkylcycloalkyl group having 6 to 11 carbon atoms such as a cyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, a dimethylcycloheptyl group, a methylethylcycloheptyl group, or a diethylcycloheptyl group (alkyl The group may be linear or branched, and the bonding position to the cycloalkyl group is also arbitrary); aryl group such as phenyl group, naphthyl group; tolyl group, xylyl group, ethylphenyl group, propylphenyl group Each alkylaryl group having 7 to 12 carbon atoms such as butylphenyl group, pentylphenyl group, hexylphenyl group (the alkyl group may be linear or branched, and the bonding position to the aryl group is arbitrary) ); Benzyl group, phenylethyl group, phenylpropyl group C7-12 arylalkyl groups such as phenylbutyl group, phenylpentyl group, phenylhexyl group (the alkyl group may be linear or branched, and the bonding position of the aryl group to the alkyl group is arbitrary) ) And the like.

The alkoxy group having 1 to 18 carbon atoms represented by Y ¹ and Y ² in the general formula (24) is a residue obtained by removing a hydrogen atom from a hydroxyl group of an alkyl alcohol having 1 to 18 carbon atoms (—OR ⁶¹ ; R ⁶¹ Is an alkyl group having 1 to 18 carbon atoms. The alkyl group having 1 to 18 carbon atoms represented by R ^61, include the exemplified alkyl group in the description of the alkyl group having 1 to 18 carbon atoms represented by ^{R 55} in the general formula (22).

The monoalkylamino group having 1 to 18 carbon atoms represented by Y ¹ and Y ² in the general formula (24) is a residue (—NHR) obtained by removing a hydrogen atom from the amino group of a monoalkylamine having 1 to 18 carbon atoms. ^{62; R 62} is an alkyl group) having 1 to 18 carbon atoms. The alkyl group having 1 to 18 carbon atoms represented by R ^62, include the exemplified alkyl group in the description of the alkyl group having 1 to 18 carbon atoms represented by ^{R 55} in the general formula (22).

In the general formula (25), the alkylene group having 2 to 18 carbon atoms represented by R ^59, include an ethylene group, a propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, Nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and other alkylene groups (these alkylene groups may be linear or branched), etc. Can be mentioned.

Y ³ in the general formula (25) and Y ⁴ in the general formula (26) are each a C 1-30 organic group containing a nitrogen atom. The number of nitrogen atoms in the organic group represented by Y ³ and Y ⁴ is not particularly limited, but is preferably one. Further, the carbon number of the organic group represented by ^{Y 3} and ^{Y 4} are as defined above 30, preferably 1 to 20, more preferably 1 to 16.

The organic group represented by Y ³ and Y ⁴ is preferably a group further containing an oxygen atom, and is preferably a group having a ring. In particular, it is preferable that the organic groups represented by Y ³ and Y ⁴ have a ring containing an oxygen atom from the viewpoint of sludge suppression, wear resistance, and friction characteristics. Further, when the organic group represented by Y ³ and Y ⁴ is a group having a ring, the ring may be either an aliphatic ring or an aromatic ring, but is preferably an aliphatic ring. Furthermore, the ring of the organic group represented by Y ³ and Y ⁴ is preferably a 6-membered ring from the viewpoints of sludge suppression, wear resistance, and friction characteristics.

Specific examples of the organic group represented by Y ³ and Y ⁴ include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, and a benzoylamino group. Morpholino group, pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, pyrazino group, etc., among which morpholino group is particularly preferable .

  Preferred examples of the compounds represented by the above general formulas (22) to (24) include alkyl acrylates having 1 to 18 carbon atoms, alkyl methacrylates having 1 to 18 carbon atoms, olefins having 2 to 20 carbon atoms, styrene, Examples thereof include methylstyrene, maleic anhydride ester, maleic anhydride amide, and a mixture thereof.

  Preferred examples of the compound represented by the general formula (25) or (26) include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, Examples include morpholinomethyl methacrylate, morpholinoethyl methacrylate, N-vinylpyrrolidone, and mixtures thereof.

  Among the compounds represented by the general formulas (22) to (24), from the viewpoint of low temperature performance, the monomer (J-1) is preferably a compound represented by the general formula (22). On the other hand, the monomer (J-2) is represented by the general formula (25) among the compounds represented by the general formula (25) or (26) from the viewpoint of sludge suppression, wear resistance, and friction characteristics. Are preferred.

  When the monomer (J-1) and the monomer (J-2) are copolymerized, the polymerization ratio (molar ratio) between the monomer (J-1) and the monomer (J-2) is arbitrary, but 80:20 It is preferable to be within the range of ~ 95: 5. The copolymerization reaction method is also arbitrary. Usually, the monomer (J-1) and the monomer (J-2) are subjected to radical solution polymerization in the presence of a polymerization initiator such as benzoyl peroxide. This copolymer can be obtained easily and reliably. Although the number average molecular weight of the copolymer obtained is also arbitrary, Preferably it is 1,000-1,500,000, More preferably, it is 10,000-200,000.

  (J) The content of the dispersion type viscosity index improver is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 2% by mass or less, based on the total amount of the composition. Even if the content exceeds 10% by mass, no further improvement in sludge suppression, wear resistance and frictional properties commensurate with the content is observed, and viscosity reduction due to shear tends to occur. Further, the content of the (J) dispersion type viscosity index improver is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more, based on the total amount of the composition. It is. When the content is less than 0.01% by mass, the sludge inhibiting property, wear resistance and frictional properties tend to be lowered.

Further, the lubricating oil composition of the present invention is represented by the following general formulas (27) to (29) from the viewpoint of further improving the friction characteristics and improving the durability of the effect of improving the friction characteristics. It is preferable to further contain a compound.
^{_{R 63 -CO-NR 64 - (}} CH 2) p -COOW 1 (27)
[Wherein R ⁶³ is an alkyl group having 6 to 30 carbon atoms or an alkenyl group having 6 to 30 carbon atoms, R ⁶⁴ is an alkyl group having 1 to 4 carbon atoms, W ¹ is a hydrogen atom, and an alkyl having 1 to 30 carbon atoms. Group or an alkenyl group having 1 to 30 carbon atoms, p represents an integer of 1 to 4, respectively. ]
_{^{[R 65 -CO-NR 66 -}} (CH 2) q -COO] r W 2 (28)
[Wherein R ⁶⁵ is an alkyl group having 6 to 30 carbon atoms or an alkenyl group having 6 to 30 carbon atoms, R ⁶⁶ is an alkyl group having 1 to 4 carbon atoms, W ² is an alkali metal or alkaline earth metal atom, s Is an integer from 1 to 4, and r is 1 when W ² is an alkali metal atom, and ² when W ² is an alkaline earth metal atom. ]
_{^{[R 67 -CO-NR 68 -}} (CH 2) s -COO] t -W 3 - (OH) u (29)
[Wherein, R ⁶⁷ represents an alkyl group having 6 to 30 carbon atoms or an alkenyl group having 6 to 30 carbon atoms, R ⁶⁸ represents an alkyl group having 1 to 4 carbon atoms, and W ³ represents a hydroxyl group of a polyhydric alcohol having two or more valences. except residues, s represents an integer of 1 to 4, t is an integer of 1 or more, u is an integer of 0 or more, respectively, t + u is the valence of ^{W 3.} ]
In general formulas (27) to (29), R ⁶³ , R ⁶⁵ and R ⁶⁷ each represent an alkyl group having 6 to 30 carbon atoms or an alkenyl group having 6 to 30 carbon atoms. From the viewpoint of solubility in base oil, the alkyl group or alkenyl group must have 6 or more carbon atoms, preferably 7 or more carbon atoms, and more preferably 8 or more carbon atoms. Further, from the viewpoint of storage stability and the like, it is necessary that the alkyl group or alkenyl group has 30 or less carbon atoms, preferably 24 or less carbon atoms, and more preferably 20 or less carbon atoms. Specific examples of such alkyl groups and alkenyl groups include hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, Alkyl groups such as heptadecyl group, octadecyl group, nonadecyl group, icosyl group (these alkyl groups may be linear or branched); hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group Group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, icocenyl group and the like alkenyl groups (these alkenyl groups may be linear or branched, and the position of the double bond) Are also optional)

In General Formulas (27) to (29), R ⁶⁴ , R ⁶⁶ and R ⁶⁸ each represent an alkyl group having 1 to 4 carbon atoms. From the viewpoint of storage stability and the like, it is necessary that the alkyl group has 4 or less carbon atoms, preferably 3 or less carbon atoms, and more preferably 2 or less carbon atoms. In general formulas (27) to (29), p, q, and s each represent an integer of 1 to 4. From the viewpoint of storage stability and the like, it is necessary to be an integer of 4 or less, preferably 3 or less, and more preferably 2 or less.

In General Formula (27), W ¹ represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 1 to 30 carbon atoms. The alkyl group or alkenyl group represented by W ¹ needs to have 30 or less carbon atoms from the viewpoint of storage stability and the like, preferably 20 or less carbon atoms, and more preferably 10 or less carbon atoms. preferable. Specific examples of such an alkyl group or alkenyl group include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. (These alkyl groups may be linear or branched); alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group (these alkenyl groups) May be linear or branched, and the position of the double bond is arbitrary). Moreover, it is preferable that it is an alkyl group from points, such as being excellent in sludge resistance. X is preferably hydrogen, an alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 1 to 20 carbon atoms from the viewpoint of improving friction characteristics and improving the durability of the friction characteristic effect. Or it is more preferable that it is a C1-C20 alkyl group, and it is still more preferable that it is hydrogen or a C1-C10 alkyl group.

In the general formula (28), W ² represents an alkali metal atom or an alkaline earth metal atom, and specific examples thereof include sodium, potassium, magnesium, calcium and the like. Among these, alkaline earth metals are preferable from the viewpoint of improving the sustainability of the friction characteristic effect. In the general formula (28), r represents 1 when W ² is an alkali metal atom, and represents ² when W ² is an alkaline earth metal atom.

In the general formula (29), W ³ represents a residue excluding a hydroxyl group of a dihydric or higher polyhydric alcohol. Specific examples of such polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,2-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2- Octanediol, 1,8-octanediol, isoprene glycol, 3-methyl-1,5-pentanediol, sorbite, catechol, resorcin, hydroquinone, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, dimer diol Divalent alcohols such as glycerin, 2- (hydroxymethyl) -1,3-propanediol, 1,2,3-butanetriol, 1,2,3-pentanetriol, 2-methyl-1,2,3 -Propanetriol, 2-methyl-2,3,4- Tantriol, 2-ethyl-1,2,3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 4-propyl-3,4,5-heptanetriol, 2,4 -Trihydric alcohols such as dimethyl-2,3,4-pentanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, trimethylolethane, trimethylolpropane; pentaerythritol, erythritol, 1, 2,3,4-pentanetetrol, 2,3,4,5-hexanetetrol, 1,2,4,5-pentanetetrol, 1,3,4,5-hexanetetrol, diglycerin, sorbitan Tetrahydric alcohols such as adonitol, arabitol, xylitol, triglycerin, etc .; dipentaerythritol Le, sorbitol, mannitol, iditol, inositol, dulcitol, talose, hexavalent alcohols such as allose, polyglycerin or their dehydrated condensates and the like.

In the general formula (29), t is an integer of 1 or more, u is an integer of 0 or more, and t + u is the same as the valence of W ^3. That is, all of the hydroxyl groups of the polyhydric alcohol of W ³ may be substituted, or only a part thereof may be substituted.

  The component (K) is at least one compound selected from the above general formulas (27) to (29). From the viewpoint of improving the durability of the friction characteristic effect, the general formulas (27) and (K) It is preferable that it is at least one compound selected from 28). Further, only one compound selected from the general formulas (27) to (29) may be used alone, or a mixture of two or more compounds may be used.

  The content of the component (K) in the lubricating oil composition of the present invention is preferably 5% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less, based on the total amount of the composition. When the content exceeds 5% by mass, the frictional properties corresponding to the content are not further improved, and the storage stability is lowered, which is not preferable. The content of the component (K) is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and still more preferably 0.005% by mass or more, based on the total amount of the composition. When the content of the component (K) is less than 0.001% by mass, the effect of improving the friction characteristics is not observed, which is not preferable.

In addition, the lubricating oil composition of the present invention further includes (L) a compound represented by the following general formula (30) from the viewpoint of further improving the friction characteristics and improving the durability of the effect of improving the friction characteristics. It is preferable to contain.
R ⁶⁹ —CH ₂ COOH (30)
[Wherein, R ⁶⁹ represents an alkyl group having 7 to 29 carbon atoms, an alkenyl group having 7 to 29 carbon atoms, or a group represented by the general formula (31).
R ⁷⁰ -C ₆ H ₄ O- (31)
(Wherein R ⁷⁰ represents an alkyl group having 1 to 20 carbon atoms or a hydrogen atom.)]
In the general formula ^{(30), R 69} represents an alkyl group, a group represented by the alkenyl group or the general formula 7 to 29 carbon atoms (31) of 7 to 29 carbon atoms. The number of carbon atoms of the alkyl group represented by R ⁶⁹ is preferably 7 or more, more preferably 9 or more, from the viewpoint of solubility in base oil. In view of storage stability and the like, the alkyl group preferably has 29 or less carbon atoms, more preferably 22 or less, and even more preferably 19 or less. Specific examples of such alkyl groups include heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, A nonadecyl group and the like (these alkyl groups may be linear or branched).

The number of carbon atoms of the alkenyl group represented by R ⁶⁹ is preferably 7 or more, more preferably 9 or more, from the viewpoint of solubility in base oil. In view of storage stability, the alkenyl group preferably has 29 or less carbon atoms, more preferably 22 or less, and even more preferably 19 or less. Specific examples of such alkenyl groups include heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, A nonadecenyl group and the like (these alkenyl groups may be linear or branched).

In the general formula ^{(31), R 70} represents an alkyl group or a hydrogen atom having 1 to 20 carbon atoms. The number of carbon atoms of the alkyl group represented by R ⁷⁰ is preferably 20 or less, more preferably 19 or less, and even more preferably 15 or less, from the viewpoint of storage stability. In view of solubility in base oil, the number of carbon atoms of the alkyl group is preferably 3 or more, and more preferably 5 or more. In the case where R ⁷⁰ is an alkyl group, the substitution position is arbitrary, but the para-position or meta-position is preferred, and the para-position is more preferred from the viewpoint of excellent frictional properties. In General Formula (30), as described above, R ⁶⁹ is an alkyl group having 7 to 29 carbon atoms or an alkenyl group having 7 to 29 carbon atoms, and is represented by General Formula (31). Although it may be a group, it is preferably a group represented by the general formula (31) from the viewpoint of superior friction characteristics.

  In the lubricating oil composition of the present invention, the content of the component (L) is arbitrary, but if blended in a large amount, the sludge resistance may be lowered, so that it is 5% by mass or less based on the total amount of the composition. It is preferably 1% by mass or less, more preferably 0.5% by mass or less. On the other hand, it is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, based on the total amount of the composition from the viewpoint of sufficiently exerting the effect of improving the friction characteristics. It is still more preferable that it is 005 mass% or more.

Moreover, the lubricating oil composition of the present invention may further contain (M) an epoxy compound. (M) As an epoxy compound, the compound shown to the following (M-1)-(M-8) is mentioned.
(M-1) Phenyl glycidyl ether type epoxy compound (M-2) Alkyl glycidyl ether type epoxy compound (M-3) Glycidyl ester type epoxy compound (M-4) Allyl oxirane compound (M-5) Alkyl oxirane compound (M -6) Alicyclic epoxy compound (M-7) Epoxidized fatty acid monoester (M-8) Epoxidized vegetable oil.

  Specific examples of the (M-1) phenyl glycidyl ether type epoxy compound include phenyl glycidyl ether and alkylphenyl glycidyl ether. As used herein, the alkylphenyl glycidyl ether includes those having 1 to 3 alkyl groups having 1 to 13 carbon atoms, and those having one alkyl group having 4 to 10 carbon atoms, such as n-butylphenyl glycidyl. Ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, heptylphenyl glycidyl ether, octylphenyl glycidyl ether, nonylphenyl glycidyl ether, decylphenyl A glycidyl ether etc. can be illustrated as a preferable thing.

  (M-2) Specifically, as the alkyl glycidyl ether type epoxy compound, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl ether, neopentyl Examples include glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, and polyalkylene glycol diglycidyl ether. .

  Specific examples of the (M-3) glycidyl ester type epoxy compound include compounds represented by the following general formula (32).

[Wherein R ⁷¹ represents a hydrocarbon group having 1 to 18 carbon atoms]
In the above formula (32), R ⁷¹ represents a hydrocarbon group having 1 to 18 carbon atoms. Examples of such a hydrocarbon group include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, C5-C7 cycloalkyl group, C6-C18 alkylcycloalkyl group, C6-C10 aryl group, C7-C18 alkylaryl group, C7-C18 arylalkyl group, etc. Is mentioned. Among these, an alkylphenyl group having an alkyl group having 5 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, a phenyl group, and an alkyl group having 1 to 4 carbon atoms is preferable.

  Among the glycidyl ester type epoxy compounds, preferred examples include glycidyl-2,2-dimethyloctanoate, glycidyl benzoate, glycidyl-tert-butyl benzoate, glycidyl acrylate, glycidyl methacrylate, and the like.

  Specific examples of (M-4) allyloxirane compounds include 1,2-epoxystyrene, alkyl-1,2-epoxystyrene, and the like.

  Specific examples of (M-5) alkyloxirane compounds include 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, and 1,2-epoxyoctane. 1,2-epoxynonane, 1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane 1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, 1,2-epoxyicosane and the like.

  (M-6) Examples of the alicyclic epoxy compound include compounds in which the carbon atom constituting the epoxy group directly constitutes the alicyclic ring, as in the compound represented by the following general formula (33). .

  Specific examples of the (M-6) alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, Bis (3,4-epoxycyclohexylmethyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1.0] ] Hept-3-yl) -spiro (1,3-dioxane-5,3 ′-[7] oxabicyclo [4.1.0] heptane, 4- (1′-methylepoxyethyl) -1,2- Examples thereof include epoxy-2-methylcyclohexane and 4-epoxyethyl-1,2-epoxycyclohexane.

  Specific examples of the (M-7) epoxidized fatty acid monoester include esters of epoxidized fatty acids having 12 to 20 carbon atoms with alcohols or phenols having 1 to 8 carbon atoms and alkylphenols. In particular, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxy stearate are preferably used.

  Specific examples of the (M-8) epoxidized vegetable oil include epoxy compounds of vegetable oils such as soybean oil, linseed oil, and cottonseed oil.

  Among these epoxy compounds, phenyl glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, alicyclic epoxy compounds, and epoxidized fatty acid monoesters are preferable because glycidyl ether can be further improved in heat and hydrolysis stability. An ester type epoxy compound and an alicyclic epoxy compound are more preferable.

  (M) When an epoxy compound is contained in the lubricating oil composition of the present invention, the content is not particularly limited, but is preferably 0.1 to 5.0% by mass, more preferably 0.8%, based on the total amount of the composition. 2 to 2.0% by mass.

  Moreover, it is preferable that the lubricating oil composition of this invention further contains (N) phenolic antioxidant and / or (P) amine antioxidant from the point of oxidation stability and sludge suppression property.

  As the (N) phenolic antioxidant, any phenolic compound used as an antioxidant for lubricating oil can be used, and although not particularly limited, the following general formula (34) or (35 The alkylphenol compound represented by this is preferable.

[Wherein R ⁷² represents an alkyl group having 1 to 4 carbon atoms, R ⁷³ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁷⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, Or the group represented by the following general formula (i) or (ii) is shown.

(In the formula, R ⁷⁵ represents an alkylene group having 1 to 6 carbon atoms, and R ⁷⁶ represents an alkyl group or alkenyl group having 1 to 24 carbon atoms.)

(In the formula, R ⁷⁷ represents an alkylene group having 1 to 6 carbon atoms, R ⁷⁸ represents an alkyl group having 1 to 4 carbon atoms, and R ⁷⁹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) ]

[Wherein, R ⁸⁰ and R ⁸⁴ may be the same or different and each represents an alkyl group having 1 to 4 carbon atoms; R ⁸¹ and R ⁸⁵ may be the same or different and each represents a hydrogen atom or a carbon number; 1 to 4 represents an alkyl group, R ⁸² and R ⁸³ may be the same or different, each represents an alkylene group having 1 to 6 carbon atoms, and A represents an alkylene group having 1 to 18 carbon atoms or the following general formula ( The group represented by iii) is shown.

—R ⁸⁶ —S—R ⁸⁷ — (iii)
(In the formula, R ⁸⁶ and R ⁸⁷ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms.)]
Specific examples of R ⁷² in the general formula (34) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Although mentioned, a tert- butyl group is preferable from the point which is excellent in oxidation stability. Examples of R ⁷³ include a hydrogen atom or an alkyl group having 1 to 4 carbon atoms as described above, and a methyl group or a tert-butyl group is preferable from the viewpoint of excellent oxidation stability.

In the case where R ⁷⁴ in the general formula (34) is an alkyl group having 1 to 4 carbon atoms, R ⁷⁴ includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -Butyl group, tert-butyl group and the like can be mentioned, and from the viewpoint of excellent oxidation stability, a methyl group or an ethyl group is preferable.

Of the alkylphenol compounds represented by the general formula (34), 2,6-di-tert-butyl-p-cresol is particularly preferable as a compound when R ⁷⁴ is an alkyl group having 1 to 4 carbon atoms. 2,6-di-tert-butyl-4-ethylphenol and mixtures thereof.

In the case where R ⁷⁴ in the general formula (34) is a group represented by the general formula (i), the alkylene group having 1 to 6 carbon atoms represented by R ⁷⁵ in the general formula (i) is linear. However, it may be branched. Specifically, for example, methylene group, methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group, straight chain or branched A butylene group, a linear or branched pentylene group, a linear or branched hexylene group, and the like.

In that can be prepared in reaction step compound is less represented by the general formula (34), R ⁷⁵ is an alkylene group having 1 to 2 carbon atoms, and specific examples include a methylene group, methyl methylene group, ethylene group (dimethylene group) Etc. are more preferable.

On the other hand, the alkyl group or alkenyl group having 1 to 24 carbon atoms represented by R ⁷⁶ in the general formula (i) may be linear or branched, and specifically includes, for example, methyl group, ethyl group, propyl group. Group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, Alkyl groups such as icosyl group, henocosyl group, docosyl group, tricosyl group, tetracosyl group (these alkyl groups may be linear or branched); vinyl group, propenyl group, isopropenyl group, butenyl group, pentenyl group Hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl Group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, octadecadienyl group, nonadecenyl group, icocenyl group, henicosenyl group, alkenyl group such as dococenyl group, tricocenyl group, tetracocenyl group, etc. The alkenyl group may be linear or branched, and the position of the double bond is arbitrary).

R ⁷⁶ is an alkyl group having 4 to 18 carbon atoms, specifically, for example, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, because of its excellent solubility in base oils. Alkyl groups such as undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, and octadecyl group (these alkyl groups may be linear or branched), and have 6 carbon atoms. A linear or branched alkyl group having ˜12 is more preferable, and a branched alkyl group having 6 to 12 carbon atoms is particularly preferable.

Among the phenol compounds represented by the general formula (34), as a compound in the case where R ⁷⁴ is a group represented by the general formula (i), R ⁷⁵ in the general formula (i) has 1 to 2 carbon atoms. R ⁷⁶ is more preferably a linear or branched alkyl group having 6 to 12 carbon atoms, and R ⁷⁵ in the general formula (i) is an alkylene group having 1 to 2 carbon atoms. R ⁷⁶ is particularly preferably a branched alkyl group having 6 to 12 carbon atoms.

  Specific examples of preferred compounds include (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-hexyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isohexyl acetate, N-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-butyl) -4-hydroxyphenyl) acetic acid n-octyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isooctyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl , (3-Methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid n-nonyl (3-Methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid isononyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid n-decyl, (3-methyl-5-tert-butyl) -4-hydroxyphenyl) isodecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-undecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, 3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-dodecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate isododecyl, (3-methyl-5-tert-butyl- 4-Hydroxyphenyl) propionate n-hexyl, (3-methyl-5-tert-butyl) 4-Hydroxyphenyl) isohexyl propionate, n-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate N-octyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isooctyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5- tert-butyl-4-hydroxyphenyl) 2-ethylhexyl propionate, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4- Hydroxyphenyl) isononyl propionate, (3-methyl -5-tert-butyl-4-hydroxyphenyl) n-decyl propionate, isodecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4 -Hydroxyphenyl) n-undecyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoundecyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate n- Dodecyl, isododecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-hexyl, (3,5-di-) tert-butyl-4-hydroxyphenyl) isohexyl acetate, (3,5-di- ert-Butyl-4-hydroxyphenyl) acetic acid n-heptyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate isoheptyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-octyl, (3,5-di-tert-butyl-4-hydroxyphenyl) isooctyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-) -Tert-butyl-4-hydroxyphenyl) acetic acid n-nonyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid isononyl, (3,5-di-tert-butyl-4-hydroxyphenyl) N-decyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3,5-di-t rt-butyl-4-hydroxyphenyl) acetic acid n-undecyl, (3,5-di-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-dodecyl, (3,5-di-tert-butyl-4-hydroxyphenyl) isododecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-hexyl, (3,5- Di-tert-butyl-4-hydroxyphenyl) isohexyl propionate, n-heptyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4- Hydroxyphenyl) isoheptyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) N-octyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isooctyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) 2-ethylhexyl propionate, (3 , 5-Di-tert-butyl-4-hydroxyphenyl) n-nonyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isononyl propionate, (3,5-di-tert-butyl) -4-hydroxyphenyl) propionate n-decyl, (3,5-di-tert-butyl-4-hydroxyphenyl) isodecylpropionate, (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-undecyl, (3,5-di-tert-butyl-4-hydroxyphenyl) propion Isoundecyl, n-dodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, isododecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and mixtures thereof Can be mentioned.

In the case where R ⁷⁴ in the general formula (34) is a group represented by the general formula (ii), R ⁷⁷ in the general formula (ii) represents an alkylene group having 1 to 6 carbon atoms. As the alkylene group may be a branched be linear, and specific examples include various alkylene groups exemplified in the description of the R ^75. R ⁷⁷ is an alkylene group having 1 to 3 carbon atoms, specifically, for example, a methylene group, a methylmethylene group, ethylene, because the compound of the general formula (34) can be produced with few reaction steps and its raw materials are easily available. A group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group and the like are more preferable. Specific examples of R ⁷⁸ in the general formula (ii) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. However, a tert-butyl group is preferable from the viewpoint of excellent oxidation stability. Examples of R ⁷⁹ include a hydrogen atom or an alkyl group having 1 to 4 carbon atoms as described above, and a methyl group or a tert-butyl group is preferable from the viewpoint of excellent oxidation stability.

Of the alkylphenol compounds represented by the general formula (34), specific examples of preferred compounds when R ⁷⁴ is a group represented by the general formula (ii) include bis (3,5- Di-tert-butyl-4-hydroxyphenyl) methane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,2-bis (3,5-di-tert- Butyl-4-hydroxyphenyl) ethane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,2-bis (3,5-di-tert-butyl-4- Hydroxyphenyl) propane, 1,3-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) Nyl) propane, and mixtures thereof.

On the other hand, in the above general formula (35), R ⁸⁰ and R ⁸⁴ may be the same or different and are each an alkyl group having 1 to 4 carbon atoms, specifically, a methyl group, an ethyl group, or an n-propyl group. , An isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and the like. From the viewpoint of excellent oxidation stability, both are preferably tert-butyl groups. R ⁸¹ and R ⁸⁵ may be the same or different, and each includes a hydrogen atom or an alkyl group having 1 to 4 carbon atoms as described above. Or a tert-butyl group.

Further, the alkylene group having 1 to 6 carbon atoms which indicates the R ⁸² and R ⁸³ in the general formula (35) may be a branched be linear, specifically, independently for each occurrence, R ^The various alkylene groups illustrated in description of ⁷⁵ are mentioned. R ⁸² and R ⁸³ are each independently an alkylene group having 1 to 2 carbon atoms, in that the compound represented by the general formula (35) can be produced by a reaction process with few compounds and the raw materials are easily available. Specifically, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group) and the like are more preferable.

  Further, in the general formula (35), the alkylene group having 1 to 18 carbon atoms represented by X specifically includes, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, and a propylene group. (Methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group , Octadecylene groups and the like (these alkylene groups may be linear or branched). From the viewpoint of easy availability of raw materials, an alkylene group having 1 to 6 carbon atoms, specifically, for example, a methylene group , Methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, Pyrene group (methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group and the like (these alkylene groups may be linear or branched) are more preferable, ethylene group (dimethylene group), trimethylene group, A linear alkylene group having 2 to 6 carbon atoms such as a linear butylene group (tetramethylene group, linear pentylene group (pentamethylene group), linear hexylene group (hexamethylene group), etc. is particularly preferred. Of the alkylphenol compounds represented, a compound represented by the following formula (36) is particularly preferred as a compound when A is an alkylene group having 1 to 18 carbon atoms.

Moreover, when A in General Formula (35) is a group represented by General Formula (iii), an alkylene group having 1 to 6 carbon atoms represented by R ⁸⁶ and R ⁸⁷ in General Formula (iii) is may be a branched be linear, specifically, individually, it includes various alkylene groups as previously described above for R ^75. Since the raw materials for producing the compound of the general formula (35) are easily available, R ⁸⁶ and R ⁸⁷ are each independently an alkylene group having 1 to 3 carbon atoms, specifically, for example, methylene group, methyl More preferred are methylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group and the like. Among the alkylphenols represented by the general formula (35), a compound represented by the following formula (37) is particularly preferable as a compound when A is a group represented by the general formula (iii).

  Of course, as the component (N) of the present invention, one compound selected from alkylphenol compounds represented by the general formulas (34) and (35) may be used alone. Furthermore, a mixture or the like of any two or more compounds selected from the above may be used.

  The content of the (N) phenolic antioxidant is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less, based on the total amount of the composition. Even if the content exceeds 3% by mass, oxidation stability sufficient to meet the content and further improvement of the sludge formation inhibiting effect are not seen, and the solubility in the base oil tends to decrease. On the other hand, the content of the (N) phenolic antioxidant is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more, based on the total amount of the composition. is there. When the content is less than 0.01% by mass, the effect of improving the oxidation stability and sludge generation inhibiting property of the lubricating oil composition due to the addition tends to be insufficient.

  In addition, as the (P) amine-based antioxidant, any amine-based compound used as an antioxidant for lubricating oil can be used, and is not particularly limited. For example, the following general formula (38) ) -Represented by phenyl-α-naphthylamine or p, p′-dialkyldiphenylamine represented by the following general formula (39).

[Wherein R ⁸⁸ represents a hydrogen atom or an alkyl group having 1 to 16 carbon atoms. ]

[Wherein, R ⁸⁹ and R ⁹⁰ may be the same or different and each represents an alkyl group having 1 to 16 carbon atoms. ]
In the general formula (38) representing phenyl-α-naphthylamine, R ⁸⁸ represents a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms. When the number of carbon atoms in R ⁸⁸ exceeds 16, the proportion of functional groups in the molecule is small, and the antioxidant ability may be weakened. The alkyl group of R ^88, specifically, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, A tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group and the like (these alkyl groups may be linear or branched).

Among the compounds represented by the general formula (38), when R ⁸⁸ is an alkyl group, a branched alkyl group having 8 to 16 carbon atoms is preferable because of its excellent solubility of the oxidation product itself in the base oil. Further, a branched alkyl group having 8 to 16 carbon atoms derived from an oligomer of an olefin having 3 or 4 carbon atoms is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene and isobutylene, but from the viewpoint of excellent solubility of its own oxidation product in the base oil, Propylene or isobutylene is preferred.

When the phenyl-α-naphthylamine represented by the general formula (38) is used as the component (N) in the present invention, R ⁸⁸ is a branched octyl group derived from a hydrogen molecule or a dimer of isobutylene, propylene Branched nonyl group derived from trimer, branched dodecyl group derived from isobutylene trimer, branched dodecyl group derived from propylene tetramer, or propylene pentamer Branched pentadecyl groups are particularly preferred, branched octyl groups derived from hydrogen molecules or dimers of isobutylene, branched dodecyl groups derived from isobutylene trimers or branched dodecyl derived from propylene tetramers The group is particularly preferred.

When Np-alkylphenyl-α-naphthylamine in which R ⁸⁸ is an alkyl group is used as the phenyl-α-naphthylamine represented by the general formula (38), as this Np-alkylphenyl-α-naphthylamine, A commercially available product may be used. In addition, phenyl-α-naphthylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, or an olefin oligomer having 2 to 16 carbon atoms and phenyl-α-naphthylamine using a Friedel-Crafts catalyst. It can be easily synthesized by reacting. Specific examples of Friedel-Crafts catalysts in this case include metal halides such as aluminum chloride, zinc chloride, and iron chloride; sulfuric acid, phosphoric acid, phosphorus pentoxide, boron fluoride, acidic clay, activated clay, etc. Or an acidic catalyst.

On the other hand, in the general formula (39) representing p, p′-dialkyldiphenylamine, R ⁸⁹ and R ⁹⁰ may be the same or different and each represents an alkyl group having 1 to 16 carbon atoms. When one or both of R ⁸⁹ and R ⁹⁰ are hydrogen atoms, they themselves may settle as sludge due to oxidation. On the other hand, when the number of carbon atoms exceeds 16, the proportion of functional groups in the molecule is small. Therefore, the antioxidant ability may be weakened.

Specific examples of R ⁸⁹ and R ⁹⁰ include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, A tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group and the like (these alkyl groups may be linear or branched). Among these, as R ⁸⁹ and R ⁹⁰ , a branched alkyl group having 3 to 16 carbon atoms is preferable from the viewpoint of excellent solubility of the oxidation product itself in the base oil, and further an olefin having 3 or 4 carbon atoms, Alternatively, a branched alkyl group having 3 to 16 carbon atoms derived from the oligomer is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, isobutylene, and the like, but the solubility of its own oxidation product in a lubricating base oil is excellent. From the viewpoint, propylene or isobutylene is preferable.

When the p, p′-dialkyldiphenylamine represented by the general formula (39) is used as the component (P) in the present invention, R ⁸⁹ and R ⁹⁰ are derived from an isopropyl group derived from propylene or isobutylene. tert-butyl group, branched hexyl group derived from propylene dimer, branched octyl group derived from isobutylene dimer, branched nonyl group derived from propylene trimer, isobutylene 3 A branched dodecyl group derived from a mer, a branched dodecyl group derived from a tetramer of propylene or a branched pentadecyl group derived from a pentamer of propylene is particularly preferred, and tert-butyl derived from isobutylene. A branched hexyl group derived from a dimer of propylene, a branched hexyl group derived from a dimer of isobutylene Butyl group, a branched nonyl group derived from propylene trimer, is a branched dodecyl group derived from a tetramer of a branched dodecyl or propylene derived from a trimer of isobutylene particularly preferred.

  A commercially available product may be used as p, p'-dialkyldiphenylamine represented by the general formula (39). Further, similarly to the phenyl-α-naphthylamine represented by the general formula (38), diphenylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, an olefin having 2 to 16 carbon atoms, or these These oligomers and diphenylamine can be easily synthesized using a Friedel-Crafts catalyst. As the Friedel-Crafts catalyst at this time, specifically, for example, metal halides and acidic catalysts listed in the synthesis of phenyl-α-naphthylamine are used. As a matter of course, as the component (P) of the present invention, one compound selected from the aromatic amines represented by the general formulas (38) and (39) may be used alone. Furthermore, a mixture of two or more compounds selected from the above in an arbitrary mixing ratio may be used.

  The content of the (P) amine-based antioxidant is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less, based on the total amount of the composition. Even if the content exceeds 3% by mass, no further improvement in oxidation stability and sludge generation inhibition sufficient for the content is observed, and the solubility in base oil tends to decrease. On the other hand, the content of the (N) amine antioxidant is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more, based on the total amount of the composition. is there. When the content of the component (N) is less than 0.01% by mass, the effect of improving the oxidation stability and sludge generation suppression by the addition tends to be insufficient.

  In addition, in the lubricating oil composition of the present invention, for the purpose of further improving its performance, (J) a viscosity index improver other than a dispersion-type viscosity index improver, a detergent dispersant, a rust inhibitor, Various additives represented by metal deactivators, pour point depressants, antifoaming agents and the like may be further contained alone or in combination of several kinds.

  (J) As the viscosity index improver other than the dispersion type viscosity index improver, specifically, a copolymer of one or more monomers selected from various methacrylic acid esters or a hydrogenated product thereof, ethylene- α-Olefin copolymer (Examples of α-olefin include propylene, 1-butene, 1-pentene, etc.) or a hydride thereof, polyisobutylene or a hydrogenated product thereof, styrene-diene hydrogenated copolymer, and polyalkyl Examples include so-called non-dispersed viscosity index improvers such as styrene. Examples of the detergent dispersant other than (B) the dispersion type viscosity index improver include alkenyl succinimide, sulfonate, phenate, salicylate and the like. In the present invention, one or two or more compounds arbitrarily selected from these viscosity index improvers can be contained in any amount, but the content is usually the total amount of the composition. It is desirable that the content is 0.01 to 10% by mass.

  Specific examples of rust inhibitors include metal soaps such as fatty acid metal salts, lanolin fatty acid metal salts, and oxidized wax metal salts; partial alcohol esters such as sorbitan fatty acid esters; esters such as lanolin fatty acid esters; Examples thereof include sulfonates such as calcium sulfonate and barium sulfonate; oxidized wax; amines; phosphoric acid; In the present invention, one or two or more compounds arbitrarily selected from these rust inhibitors can be contained in any amount, but the content is usually based on the total amount of the composition. It is desirable that it is 0.01-1 mass%.

  Specific examples of the metal deactivator include benzotriazole, thiadiazole, and imidazole compounds. In the present invention, one kind or two or more kinds of compounds arbitrarily selected from these metal deactivators can be contained in any amount, but the content thereof is usually the composition. It is desirable that it is 0.001-1 mass% on the basis of the total amount.

  Specific examples of the pour point depressant include copolymers of one or more monomers selected from various acrylic esters and methacrylic esters or hydrogenated products thereof. In the present invention, one or two or more compounds arbitrarily selected from these pour point depressants can be contained in any amount, but usually the content is the total amount of the composition. It is desirable that the content is 0.01 to 5% by mass.

  Specific examples of the antifoaming agent include silicones such as dimethyl silicone and fluorosilicone. In the present invention, one or two or more compounds arbitrarily selected from these antifoaming agents can be contained in any amount, and the content is usually based on the total amount of the composition. It is desirable that it is 0.001-0.05 mass%.

The kinematic viscosity of the lubricating oil composition of the present invention is not particularly limited, but the kinematic viscosity at 40 ° C. is preferable from the viewpoints of excellent friction characteristics, cooling properties (heat removal properties), and low friction loss due to stirring resistance. Is from 5 to 1,000 mm ² / s, more preferably from 7 to 500 mm ² / s, still more preferably from 10 to ²⁰⁰ mm ² / s. In addition, the viscosity index of the lubricating oil composition of the present invention is not particularly limited, but is preferably 80 to 500, more preferably 100 to 300, from the viewpoint of suppressing oil film decrease at high temperature. Furthermore, although the pour point is also arbitrary, from the viewpoint of pump startability in winter, the pour point is usually preferably −5 ° C. or lower, more preferably −15 ° C. or lower.

  The lubricating oil composition of the present invention can be used as, for example, hydraulic fluid, turbine oil, compressor oil, gear oil, slip guide surface oil, bearing oil, and the like. Among these applications, when used as a hydraulic fluid for hydraulic equipment such as injection molding machines, machine tools, construction machines, steel making equipment, industrial robots, hydraulic elevators, etc., it is possible to exert more excellent effects. .

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.
[Examples 1-4, Comparative Examples 1-4]
In Examples 1 to 4 and Comparative Examples 1 to 4, lubricating oil compositions having the compositions shown in Tables 1 and 2 were prepared using the base oils and additives shown below, respectively.
Base oil:
Base oil 1: Paraffin-based highly solvent refined base oil (kinematic viscosity at 40 ° C .: 46.1 mm ² / s, viscosity index 100)
Base oil 2: Paraffinic hydrocracked base oil (kinematic viscosity at 40 ° C .: 46.1 mm ² / s, viscosity index 125)
(A) Polyhydric alcohol ester:
A1: Triester of glycerin and a mixed fatty acid of acetic acid, n-octadecanoic acid and oleic acid ((Z) -9-octadecenoic acid, the same shall apply hereinafter) (fatty acid composition: 66.6 mol% acetic acid, n-octadecanoic acid) 30 mol%, oleic acid 3.4 mol%)
A2: Triester of glycerin and mixed fatty acid of acetic acid, n-octadecanoic acid and oleic acid (fatty acid composition: acetic acid 67 mol%, n-octadecanoic acid 28 mol%, oleic acid 5 mol%)
A3: Triester of glycerin and a mixed fatty acid of acetic acid, n-hexadecanoic acid and (Z) -9-octadecenoic acid (oleic acid) (fatty acid composition: 66.7 mol% acetic acid, 30.1 mol n-hexadecanoic acid) %, Oleic acid 3.2 mol%)
(B) Ester oil-based agent:
B1: Monoester of glycerin and n-octadecanoic acid B2: Monoester of glycerin and oleic acid (H) Phosphorus-containing carboxylic acid compound:
H1: β-dithiophosphorylated propionic acid (I) thiophosphate ester and phosphorus antiwear agent:
I1: Triphenyl phosphate I2: Triphenylphosphorothionate (N) phenolic antioxidant:
N1: 2,6-di-tert-butyl-p-cresol (P) amine antioxidant:
P1: Dioctyldiphenylamine (X) dispersion type pour point depressant:
X1: Monotype polybutenyl succinimide obtained by reaction of polybutenyl succinic anhydride with tetraethylenepentamine.

[Thermal stability test]
For each of the lubricating oil compositions of Examples 1 to 4 and Comparative Examples 1 to 4, 50 ml of sample oil was sampled in a beaker having a capacity of 50 ml according to “Lubricating oil thermal stability method” defined in JIS K 2540, and iron and A copper coil catalyst was added, and a thermal stability test was performed for a certain period (10 days, 20 days) in an air constant temperature bath at 140 ° C. The sample oil after the test was filtered with a filter, and the amount of sludge in the sample oil was measured. The obtained results are shown in Tables 1 and 2.

[SRV (micro reciprocating friction) test]
About each lubricating oil composition of Examples 1-4 and Comparative Examples 1-4, the SRV test was done and the friction characteristic was evaluated. More specifically, as shown in FIG. 1, sample oil is applied to the point contact area between the disk 1 and the ball 2 disposed on the upper surface thereof, and the ball 2 is vertically directed downward (arrow A in the figure). The ball 2 was reciprocated relatively in the direction along the upper surface of the disk 1 (arrow B in the figure) while applying a load. The friction coefficient at this time was measured by a load cell (not shown) attached to the disk 1 cage (not shown). The disc 1 was made of SUJ2 having a diameter of 25 mm and a thickness of 8 mm, and the ball 2 was made of SUJ2 having a diameter of 10 mm. The load applied to the ball 2 was 1,200 N, the amplitude of the ball 2 was 1 mm, the frequency was 50 Hz, and the temperature was 80 ° C. The obtained results are shown in Tables 1-3.

"Abrasion resistance test"
About each lubricating oil composition of Examples 1-4 and Comparative Examples 1-4, the vane pump test prescribed | regulated to ASTMD2882 was implemented, the weight of the vane and ring before and behind a test was measured, and the amount of wear was measured. The test time was 100 hours. The obtained results are shown in Tables 1 and 2.

[Low temperature storage stability test]
100 ml of each lubricating oil composition of Examples 1 to 4 and Comparative Examples 1 to 4 was put in a glass container with a cap of 100 ml capacity, the glass container was sealed, and stored in a refrigerator at 0 ° C. The appearance of the lubricating oil composition after 60 days was observed and the presence or absence of precipitation was evaluated. The obtained results are shown in Tables 1 and 2.

  1 ... disk, 2 ... ball.

Claims (4)

At least one base oil selected from mineral oils, fats and oils, and synthetic oils;
A complete ester of a polyhydric alcohol and a fatty acid, the constituent fatty acid containing an ester containing both a short-chain fatty acid having 1 to 4 carbon atoms and a long-chain fatty acid having 10 to 24 carbon atoms,
A hydraulic fluid comprising a lubricating oil composition, wherein the ester content is 0.01 to 7.5% by mass based on the total amount of the composition. The hydraulic fluid according to claim 1, wherein the polyhydric alcohol is glycerin. The hydraulic fluid according to claim 1 or 2, wherein the base oil is at least one selected from mineral oil and synthetic oil (except monoester, diester, polyester, polyol ester and phosphate ester). The hydraulic fluid according to any one of claims 1 to 3, wherein the base oil is a mineral oil that has been hydrocracked.

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