JP7198229B2 - lubricating oil composition - Google Patents

Description

The present invention relates to lubricating oil compositions for use in turbomachinery, compressors, hydraulic equipment, or machine tools, and methods of using such lubricating oil compositions.

Lubricating oil compositions used in equipment such as various turbomachinery such as steam turbines and gas turbines, compressors such as rotary gas compressors and reciprocating compressors, hydraulic equipment, and hydraulic units of machine tools are subject to high temperatures. It may be used while circulating in an environmental system for a long period of time.
When a lubricating oil composition is used for a long period of time in a high-temperature environment, sludge is likely to deposit due to oxidative deterioration. Deposited sludge, for example, adheres to the bearings of the rotating body and generates heat, causing damage to the bearings, clogging of filters provided in the circulation line, and malfunction of the control system due to accumulation in the control valves. can cause problems.
Therefore, lubricating oil compositions that are used while circulating in a system under a high-temperature environment for a long time are required to improve the effect of suppressing sludge deposition.

For example, Patent Document 1 describes a synthetic base oil that is a mixed oil of a polyglycol synthetic oil and an ester synthetic oil, and one or more amine antioxidants selected from a specific compound group such as an asymmetric diphenylamine compound. An air compressor lubricating oil composition is disclosed containing a
According to Patent Literature 1, it is shown that the lubricating oil composition for air compressors can suppress sludge deposition while appropriately suppressing oxidation.

WO2013/146805

By the way, lubricating oil compositions used in equipment such as turbines, which are likely to be mixed with water or steam, are emulsified by contamination with water or steam, which causes troubles in the equipment.
Therefore, lubricating oil compositions used in such devices are required to be difficult to emulsify and to be easily separated from water even after emulsification, that is, to be excellent in water separability.
Note that Patent Document 1 does not discuss the water separability of the lubricating oil composition.

The present invention provides turbomachinery, compressors, hydraulic equipment, or machine tools that have excellent oxidation stability, high sludge deposition suppression effect, and excellent water separation even for long-term use in high-temperature environments. The object is to provide a lubricating oil composition for use in machinery.

The present inventors have provided a mixed base oil comprising a predetermined amount of mineral oil in combination with a synthetic oil containing polyalkylene glycols (hereinafter also referred to as "PAG") and polyol esters (hereinafter also referred to as "POE"). The inventors have found that a lubricating oil composition capable of solving the above-mentioned problems, and completed the present invention.
That is, the present invention provides the following [1] and [2].
[1] A lubricating oil composition containing a mineral oil (A) and a synthetic oil (B) containing a polyalkylene glycol (B1) and a polyol ester (B2),
The content of the mineral oil (A) is 5 to 95% by mass based on the total amount of the lubricating oil composition,
A lubricating oil composition for use in turbomachinery, compressors, hydraulic equipment or machine tools.
[2] A method of using the lubricating oil composition according to [1] above for turbomachinery, compressors, hydraulic equipment, or machine tools.

The lubricating oil composition of the present invention is excellent in oxidation stability, highly effective in suppressing sludge deposition, and excellent in water separation even when used for a long period of time in a high-temperature environment. As such, the lubricating oil composition is suitable for use in turbomachinery, compressors, hydraulic equipment, or machine tools.

In the following specification, kinematic viscosity and viscosity index mean values measured and calculated according to JIS K2283:2000.
The contents of phosphorus atoms and metal atoms are values measured according to JPI-5S-38-92.
The content of nitrogen atoms means a value measured according to JIS K2609.

[Lubricating oil composition]
The lubricating oil composition of the present invention is used for turbomachinery, compressors, hydraulic equipment, or machine tools, and comprises mineral oil (A), polyalkylene glycol (PAG) (B1) and polyol ester (POE). It contains a synthetic oil (B) containing (B2).
In the lubricating oil composition of the present invention, by using a mixed base oil in which a mineral oil (A) and a synthetic oil containing PAG and POE are used together as a base oil, it is possible to use it for a long time in a high temperature environment. , excellent in oxidation stability, highly effective in suppressing sludge deposition, and excellent in water separation.

Mineral oil is excellent in water separability, but has poor oxidation stability in a high-temperature environment and tends to produce degraded products, which precipitate as sludge and cause malfunctions in equipment.
PAG has the property of dissolving degraded substances that may be generated in a high-temperature environment and suppressing the precipitation of the degraded substances as sludge, but it has a problem in water separation. In addition, since the polarity is too high, the compatibility with non-polar base oils such as mineral oil is poor, so it is difficult for a mixed base oil of mineral oil and PAG to exhibit performances that complement each other's shortcomings.
On the other hand, POE is inferior to PAG in terms of the solubility of degraded substances that can occur in a high-temperature environment, but it has the property of being excellent in compatibility with other base oils, so it is compatible with both PAG and mineral oil. have good compatibility with POE also has a problem in water separation.
Therefore, in the present invention, by combining three types of base oils, mineral oil, PAG, and POE, the characteristics of "mineral oil" that is excellent in water separation, and the deterioration of "PAG" that can occur in a high-temperature environment It is possible to obtain a lubricating oil composition capable of exhibiting a well-balanced characteristic of being able to dissolve

When a base oil that contains PAG and POE but does not contain mineral oil is used, there is a problem with water separability, and addition of additives tends to lower the water separability.
On the other hand, when a base oil containing mineral oil and POE but not containing PAG is used, the solubility of degraded substances that may occur in a high-temperature environment is inferior to that when PAG is used alone.
Furthermore, when a base oil that contains mineral oil and PAG but does not contain POE is used, the compatibility between mineral oil and PAG is poor, so the characteristics of mineral oil and the characteristics of PAG are difficult to develop.
That is, in the present invention, since the three base oils of mineral oil, PAG, and POE are used in combination, it is possible to compensate for the disadvantages of each base oil with the other base oil while taking advantage of the advantages of each.
As a result, the lubricating oil composition of the present invention has excellent oxidation stability, high sludge deposition suppression effect, and excellent water separation even when used for a long period of time in a high-temperature environment.

From the viewpoint of providing a lubricating oil composition that has excellent oxidation stability and a high effect of suppressing sludge deposition even for long-term use in a high-temperature environment, the lubricating oil composition of one embodiment of the present invention further includes: It is preferable to contain an antioxidant (C) containing an amine antioxidant (C1).
Further, from the viewpoint of improving wear resistance, the lubricating oil composition of one embodiment of the present invention further includes a neutral phosphate (D1), an acidic phosphate (D2), and an amine salt of an acidic phosphate. It preferably contains one or more phosphorus compounds (D) selected from (D3).
The lubricating oil composition of one aspect of the present invention may contain lubricating oil additives other than components (C) and (D) within a range that does not impair the effects of the present invention.

In the lubricating oil composition of one aspect of the present invention, the total content of components (A) and (B) is usually 65% by mass or more, preferably 70% by mass, based on the total amount (100% by mass) of the lubricating oil composition. % by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually 100% by mass or less, preferably 99.9% by mass or less.

In the lubricating oil composition of one aspect of the present invention, the total content of components (A), (B), (C) and (D) is based on the total amount (100% by mass) of the lubricating oil composition, preferably is 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and even more preferably 97 to 100% by mass.
Each component contained in the lubricating oil composition of one embodiment of the present invention will be described below.

<Mineral oil (A)>
The mineral oil (A) used in the present invention includes, for example, atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oils, intermediate crude oils, and naphthenic crude oils; Distillate oil obtained by: Mineral oil obtained by subjecting the distillate oil to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining; Mineral oil (GTL) obtained by isomerizing wax (GTL wax (Gas To Liquids WAX)) produced from natural gas by the Fischer-Tropsch process or the like can be mentioned.
These mineral oils may be used alone or in combination of two or more.
As the mineral oil (A) used in one aspect of the present invention, a mineral oil classified into Group 2 or 3 of the API (American Petroleum Institute) base oil category is preferable.

The kinematic viscosity at 40° C. of the mineral oil (A) used in one aspect of the present invention is preferably 8 to 350 mm ² /s, more preferably 10 to 150 mm ² /s, still more preferably 12 to 100 mm ² /s, and more More preferably, it is 15 to 68 mm ² /s.

The mineral oil (A) used in one embodiment of the present invention preferably has a viscosity index of 80 or higher, more preferably 90 or higher, and even more preferably 100 or higher.

In the lubricating oil composition of the present invention, the content of component (A) is 5 to 95% by mass, preferably 10 to 95% by mass, based on the total amount (100% by mass) of the lubricating oil composition. It is preferably 20 to 93% by mass, more preferably 40 to 92% by mass, still more preferably 60 to 90% by mass.
If the content of component (A) is less than 5% by mass, the lubricating oil composition will have poor water separability.
On the other hand, if the content of component (A) exceeds 95% by mass, the content of components (B1) and (B2) cannot be sufficiently ensured, so sludge is likely to precipitate in a high-temperature environment, and oxidation stability is poor. It becomes a lubricating oil composition.

Further, in the lubricating oil composition of one aspect of the present invention, the content ratio of the component (A) to the total content of the component (B1) and the component (B2) [(A) / ((B1) + (B2) )] is preferably 0.05 or more, more preferably 0.10 or more, more preferably 0.30 or more, and still more preferably 0 0.70 or more, more preferably 1.50 or more, and particularly preferably 3.50 or more. From the viewpoint of obtaining a high lubricating oil composition, it is preferably 19.0 or less, more preferably 15.0 or less, and more preferably 12.0 or less.

<Synthetic oil (B)>
The synthetic oil (B) contained in the lubricating oil composition of the present invention contains polyalkylene glycol (B1) and polyol ester (B2).
The synthetic oil (B) used in one aspect of the present invention may further contain synthetic oils other than the components (B1) and (B2) within a range that does not impair the effects of the present invention.
However, in the lubricating oil composition of one aspect of the present invention, the total content of the components (B1) and (B2) in the synthetic oil (B) is the amount of the synthetic oil (B) contained in the lubricating oil composition. Based on the total amount (100% by mass), preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

In the lubricating oil composition of one aspect of the present invention, even for long-term use in a high temperature environment, from the viewpoint of a lubricating oil composition that has excellent oxidation stability and a high effect of suppressing sludge deposition, the component (B1 ) and component (B2) [(B1)/(B2)] is preferably 10/90 to 80/20, more preferably 15/85 to 70/30, and still more preferably 20/80 to 60/40, more preferably 25/75 to 55/45.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B) is based on the total amount (100% by mass) of the lubricating oil composition, even for long-term use in a high temperature environment. From the viewpoint of obtaining a lubricating oil composition that is excellent in stability and highly effective in suppressing sludge deposition, it is preferably 5% by mass or more, more preferably 6% by mass or more, still more preferably 7% by mass or more, and even more preferably 8% by mass. % or more, and from the viewpoint of making a lubricating oil composition excellent in water separation, preferably 95% by mass or less, more preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 60% by mass % or less, more preferably 40 mass % or less, particularly preferably 20 mass % or less.

[Polyalkylene glycol (B1)]
Examples of polyalkylene glycol (B1) include polymers obtained by polymerizing or copolymerizing alkylene oxides.
In addition, polyalkylene glycol (B1) may be used independently and may use 2 or more types together.

The number average molecular weight (Mn) of the polyalkylene glycol (B1) used in one aspect of the present invention is preferably 200 to 10,000, more preferably 240 to 5, from the viewpoint of improving the viscosity index of the lubricating oil composition. ,000, more preferably 280 to 3,000, and even more preferably 320 to 1,500.
In the present specification, the number average molecular weight (Mn) is a value converted to standard polystyrene measured by a gel permeation chromatography (GPC) method, and the measurement conditions include the conditions described in Examples. .

In addition, the polyalkylene glycol (B1) used in one aspect of the present invention is a polyalkylene having at least one or more of the terminals blocked with a substituent from the viewpoint of a lubricating oil composition having a further improved effect of suppressing sludge deposition. Glycols are preferred.
Examples of the substituents capable of blocking the ends of polyalkylene glycol include monovalent hydrocarbon groups having 1 to 10 carbon atoms, acyl groups having 2 to 10 carbon atoms, or heterocyclic groups having 3 to 10 ring atoms. A cyclic group can be mentioned, and a monovalent hydrocarbon group having 1 to 10 carbon atoms is preferable.
Specific examples of monovalent hydrocarbon groups, acyl groups, and heterocyclic groups that can be selected as the substituents, and suitable carbon number or ring-forming atom number ranges are described below. Same as the definition for R ^B1 and R ^B3 in (b-1).

In one aspect of the present invention, the polyalkylene glycol (B1) is a compound represented by the following general formula (b-1) from the viewpoint of providing a lubricating oil composition having a further improved effect of suppressing sludge deposition. is preferred.
R ^B1 -[(OR ^B2 ) _a -OR ^B3 ] _b (b-1)

In the above general formula (b-1), R ^B1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, a divalent to hexavalent hydrocarbon group having 1 to 10 carbon atoms, It is a hydrocarbon group or a heterocyclic group having 3 to 10 ring atoms.
R ^B2 is an alkylene group having 2 to 4 carbon atoms.
R ^B3 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or a heterocyclic group having 3 to 10 ring atoms.

b is an integer of 1-6, preferably an integer of 1-4, more preferably 1-3, still more preferably 1;
Incidentally, b is determined according to the number of bonding sites with R ^B1 in the general formula (b-1).
For example, b is 1 when R ^B1 is a monovalent hydrocarbon group such as an alkyl group or a cycloalkyl group or an acyl group. That is, when R ^B1 is a hydrocarbon group or a heterocyclic group and the valences of the group are 1, 2, 3, 4, 5, and 6, b is 1, 2, 3, 4, 5, respectively. and 6.

a is a number of 1 or more, and is a value appropriately set according to the value of the number average molecular weight of the compound represented by the general formula (b-1).
When two or more different compounds represented by the general formula (b-1) are used, the value of a is the average value (weighted average value), and the average value may be 1 or more.
Moreover, when a plurality of R ^B2 and R ^B3 are present, the plurality of R ^B2 and R ^B3 may be the same or different.

In one aspect of the present invention, at least one of R 1 ^B1 and R 2 ^B3 in the general formula (b-1) is a monovalent hydrocarbon group having 1 to 10 carbon atoms and an acyl group having 2 to 10 carbon atoms. , preferably a divalent to hexavalent hydrocarbon group having 1 to 10 carbon atoms, or a heterocyclic group having 3 to 10 ring atoms, and a monovalent hydrocarbon group having 1 to 10 carbon atoms. is more preferred.

Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms that can be selected as R 1 ^B1 and R 1 ^B3 include methyl group, ethyl group, propyl group (n-propyl group, isopropyl group), butyl group (n- butyl group, isobutyl group, s-butyl group, t-butyl group), pentyl group, hexyl group, heptyl group, octyl group, nonyl group, alkyl group such as decyl group; cyclopentyl group, cyclohexyl group, methylcyclohexyl group, ethyl Cycloalkyl groups such as cyclohexyl group, propylcyclohexyl group and dimethylcyclohexyl group; Aryl groups such as phenyl group, methylphenyl group, ethylphenyl group, dimethylphenyl group, propylphenyl group, trimethylphenyl group, butylphenyl group and naphthyl group; arylalkyl groups such as a benzyl group, a phenylethyl group, a methylbenzyl group, a phenylpropyl group, a phenylbutyl group; and the like.
The above alkyl group may be either linear or branched.
The number of carbon atoms in the monovalent hydrocarbon group is preferably 1-10, more preferably 1-6, still more preferably 1-4.

The hydrocarbon group portion of the acyl group having 2 to 10 carbon atoms which can be selected as R 1 ^B1 and R 1 ^B3 may be linear, branched or cyclic. Examples of the hydrocarbon group portion include those having 1 to 9 carbon atoms among the monovalent hydrocarbon groups that can be selected as R 1 ^B1 and R 2 ^B3 .
The acyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms.

The divalent to hexavalent hydrocarbon group that can be selected as R 1 ^B1 includes a residue obtained by removing 1 to 5 hydrogen atoms from the above monovalent hydrocarbon group that can be selected as R 1 ^B1 , and trimethylolpropane. , glycerin, pentaerythritol, sorbitol, 1,2,3-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, and other polyhydric alcohols from which hydroxyl groups have been removed.
The divalent to hexavalent hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 4 carbon atoms.

The heterocyclic group having 3 to 10 ring-forming atoms which can be selected as R 1 ^B1 and R 2 ^B3 is preferably an oxygen atom-containing heterocyclic group or a sulfur atom-containing heterocyclic group. In addition, the heterocyclic group may be a saturated ring or an unsaturated ring.
Examples of the oxygen atom-containing heterocyclic group include oxygen atom-containing saturated heterocyclic rings such as 1,3-propylene oxide, tetrahydrofuran, tetrahydropyran, and hexamethylene oxide, acetylene oxide, furan, pyran, oxycycloheptatriene, Examples thereof include residues obtained by removing 1 to 6 hydrogen atoms from an oxygen atom-containing unsaturated heterocyclic ring such as isobenzofuran and isochromene.
Examples of the sulfur atom-containing heterocyclic group include sulfur atom-containing saturated heterocycles such as ethylene sulfide, trimethylene sulfide, tetrahydrothiophene, tetrahydrothiopyran, and hexamethylene sulfide, acetylene sulfide, thiophene, thiapyran, and Examples thereof include residues obtained by removing 1 to 6 hydrogen atoms from a sulfur atom-containing unsaturated heterocyclic ring such as thiotripylidene.
The number of ring-forming atoms in the heterocyclic group is preferably 3-10, more preferably 3-6, still more preferably 5 or 6.

The alkylene group having 2 to 4 carbon atoms that can be selected as R ^B2 includes, for example, an alkylene group having 2 carbon atoms such as an ethylene group (--CH ₂ CH ₂ --); a trimethylene group (--CH ₂ CH ₂ CH ₂ -- ), 1-methylethylene group (propylene group) (—CH(CH ₃ )CH ₂ —) and other alkylene groups having 3 carbon atoms; tetramethylene group (—CH ₂ CH ₂ CH ₂ CH ₂ —), 1-methyl trimethylene group (-CH _{( CH3} ) _CH2CH2- ), _{2 -} methyltrimethylene group ( _-CH2CH ( _CH3 )CH2-), butylene group (-C( _CH3 ) _2CH2- ), 1-ethylethylene group (-CH(CH ₂ CH ₃ )CH ₂ -, 1,2-dimethylethylene group (-CH(CH ₃ )-CH(CH ₃ )-) and other alkylene groups having 4 carbon atoms is mentioned.
In addition, when a plurality of R 2 ^B2 are present, the plurality of R ^{2 B2} may be the same as each other, or may be a combination of two or more alkylene groups.
Among these, R ^B2 is preferably an ethylene group (--CH ₂ CH ₂ --) or a 1-methylethylene group (propylene group) (--CH(CH ₃ )CH ₂ --).

In the compound represented by the general formula (b-1), the content of the oxypropylene unit (—OCH(CH ₃ )CH ₂ —) is the oxyalkylene (OR ^B2 in the formula) in the structure of the compound. ) is preferably 50 to 100 mol%, more preferably 65 to 100 mol%, and still more preferably 80 to 100 mol% based on the total amount (100 mol%) of ).

The kinematic viscosity at 40° C. of component (B1) used in one aspect of the present invention is preferably 8 to 350 mm ² /s, more preferably 10 to 150 mm ² /s, still more preferably 12 to 100 mm ² /s, and more More preferably, it is 15 to 68 mm ² /s.

The viscosity index of component (B1) used in one aspect of the present invention is preferably 90 or higher, more preferably 100 or higher, even more preferably 120 or higher, and even more preferably 140 or higher.

In the lubricating oil composition of one aspect of the present invention, the content of component (B1) is preferably 1.0 to 70% by mass, more preferably 1.0 to 70% by mass, based on the total amount (100% by mass) of the lubricating oil composition. 2 to 50% by mass, more preferably 1.4 to 30% by mass, still more preferably 1.5 to 20% by mass, even more preferably 1.7 to 12% by mass, particularly preferably 1.9 to 6% by mass is.

[Polyol ester (B2)]
As the polyol ester (B2), for example, a hindered polyol having one or more quaternary carbon atoms in the molecule and having 1 to 4 methylol groups bonded to at least one of the quaternary carbon atoms; Hindered esters, which are esters with aliphatic monocarboxylic acids, are included.
The polyol ester (B2) may be used alone or in combination of two or more.

Incidentally, the polyol ester (B2) is usually a complete ester in which all the hydroxyl groups of the polyol are esterified. may contain a partial ester.

The hindered polyol is preferably a compound represented by the following general formula (b-2).

In the general formula (b-2), R 1 ^B11 and R 1 ^B12 are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a methylol group (--CH ₂ OH).
n represents an integer of 0 to 4, preferably 0 to 2, more preferably 0 to 1, still more preferably 0; When n=0, it becomes a single bond, resulting in a compound represented by the following general formula (b-2').

〔前記一般式（ｂ－２’）中、Ｒ^Ｂ１１及びＲ^Ｂ１２は、それぞれ独立に、炭素数１～６の一価の炭化水素基、又はメチロール基（－ＣＨ_２ＯＨ）である。〕

[In the general formula (b-2'), R ¹¹ and R ¹² are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a methylol group (-CH ₂ OH). ]

Examples of monovalent hydrocarbon groups having 1 to 6 carbon atoms that can be selected as R 1 ^B11 and R 1 ^B12 include alkyl groups having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group, , hexyl group), cyclopentyl group, cyclohexyl group, phenyl group and the like.
The above alkyl group may be either linear or branched.
Among these, the monovalent hydrocarbon group having 1 to 6 carbon atoms that can be selected as R 1 ^B11 and R 1 ^B12 is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. preferable.

Examples of compounds represented by the following general formula (b-2) include dialkylpropanediol (wherein the alkyl group has 1 to 6 carbon atoms) and trimethylolalkane (wherein the alkane has 2 to 7 carbon atoms). , pentaerythritol and other hindered polyols and dehydration condensates thereof, more specifically neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1 , 3-propanediyl, trimethylolethane, trimethylolpropane, trimethylolbutane, trimethylolpentane, trimethylolhexane, trimethylolheptane, pentaerythritol, 2,2,6,6-tetramethyl-4-oxa-1, 7-heptanediol, 2,2,6,6,10,10-hexamethyl-4,8-dioxa-1,11-undecadiol, 2,2,6,6,10,10,14,14-octamethyl -4,8,12-trioxa-1,15-pentadecadiol, 2,6-di(hydroxymethyl)-2,6-dimethyl-4-oxa-1,7-heptanediol, 2,6,10- tri(hydroxymethyl)-2,6,10-trimethyl-4,8-dioxa-1,11-undecadiol, 2,6,10,14-tetra(hydroxymethyl)-2,6,10,14- tetramethyl-4,8,12-trioxa-1,15-pentadecadiol, di(pentaerythritol), tri(pentaerythritol), tetra(pentaerythritol), penta(pentaerythritol) and the like.
Among these, trimethylolpropane, neopentylglycol, pentaerythritol, and bimolecular or trimolecular dehydration condensates thereof are preferred, trimethylolpropane, neopentylglycol, and pentaerythritol are more preferred, and trimethylolpropane is further preferred. preferable.

Examples of the aliphatic monocarboxylic acid include saturated aliphatic monocarboxylic acids having 5 to 22 carbon atoms.
The acyl group of the saturated aliphatic monocarboxylic acid may be linear or branched.
Examples of saturated aliphatic monocarboxylic acids include valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, linear saturated monocarboxylic acids such as stearic acid, nonadecanic acid, arachidic acid, behenic acid; 2-dimethylpentanoic acid, 2,2-dimethyloctanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,5,5-trimethyl-2 - branching of t-butylhexanoic acid, 2,3,3-trimethyl-2-ethylbutanoic acid, 2,3-dimethyl-2-isopropylbutanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, etc. saturated monocarboxylic acids and the like.
These aliphatic monocarboxylic acids may be used singly or in combination of two or more in the esterification.
The number of carbon atoms in the saturated aliphatic monocarboxylic acid is preferably 5-18, more preferably 6-14, still more preferably 8-10.

The kinematic viscosity at 40° C. of the polyol ester (B2) used in one aspect of the present invention is preferably 8 to 350 mm ² /s, more preferably 10 to 150 mm ² /s, still more preferably 11 to 100 mm ² /s, Even more preferably 12 to 68 mm ² /s.

The viscosity index of the polyol ester (B2) used in one embodiment of the present invention is preferably 90 or higher, more preferably 100 or higher, still more preferably 110 or higher, and still more preferably 120 or higher.

The number average molecular weight (Mn) of the polyol ester (B2) used in one embodiment of the present invention is preferably 100 to 8,000, more preferably 200 to 4,000, still more preferably 300 to 2,000, and still more It is preferably 400 to 1,000.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B2) is based on the total amount (100% by mass) of the lubricating oil composition, preferably 2.0 to 90% by mass, more preferably 2 .5 to 70% by mass, more preferably 3.0 to 55% by mass, still more preferably 3.5 to 40% by mass, even more preferably 4.0 to 30% by mass, particularly preferably 4.5 to 15% by mass %.

[Synthetic oil other than components (B1) and (B2)]
Synthetic oil (B) used in one aspect of the present invention may further contain synthetic oil other than components (B1) and (B2) within a range that does not impair the effects of the present invention.
Other synthetic oils include, for example, α-olefin homopolymers, α-olefin copolymers (eg, α-olefin copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers), etc. poly α-olefin; isoparaffin; dibasic acid ester (e.g., ditridecyl glutarate), aromatic ester (e.g., 2-ethylhexyl trimellitate, 2-ethylhexyl pyromellitic acid), components such as phosphate ester ( various esters other than B2); various ethers other than component (B1) such as polyphenyl ether; alkylbenzene; alkylnaphthalene;
These synthetic oils may be used alone or in combination of two or more.

<Antioxidant (C)>
The lubricating oil composition of one aspect of the present invention has good oxidation stability, suppresses the generation of deterioration products, and improves the effect of suppressing sludge deposition. It is preferable to contain an antioxidant (C) containing an antioxidant (C1).
The antioxidant (C) used in one aspect of the present invention may further contain an antioxidant other than the amine antioxidant (C1) together with the amine antioxidant (C1).

In the lubricating oil composition of one aspect of the present invention, the content of the component (C1) in the component (C) suppresses the generation of deterioration products, further improves the effect of suppressing sludge deposition, and oxidizes From the viewpoint of obtaining a lubricating oil composition with excellent stability, the total amount (100% by mass) of component (C) is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, and still more preferably 60 to 100% by mass, more preferably 70 to 100% by mass.

In the lubricating oil composition of one aspect of the present invention, the content of the component (C) suppresses the generation of deterioration products, further improves the effect of suppressing sludge deposition, and is a lubricating oil excellent in oxidation stability. From the viewpoint of the composition, based on the total amount (100% by mass) of the lubricating oil composition, preferably 0.01 to 10% by mass, more preferably 0.05 to 7% by mass, still more preferably 0.1 to 5% by mass.

[Amine antioxidant (C1)]
The amine-based antioxidant (C1) may be any amine-based compound having antioxidant performance, and includes naphthylamine (C11), diphenylamine (C12), and the like.
The amine antioxidant (C1) may be used alone or in combination of two or more.
In addition, in one aspect of the present invention, it is preferable that both naphthylamine (C11) and diphenylamine (C12) are included.

In the lubricating oil composition of one aspect of the present invention, the content ratio [(C11)/(C12)] of naphthylamine (C11) and diphenylamine (C12) is preferably 10/90 to 90/ 10, more preferably 15/85 to 85/15, more preferably 20/80 to 80/20, even more preferably 25/75 to 75/25.

Examples of naphthylamine (C11) include phenyl-α-naphthylamine, phenyl-β-naphthylamine, alkylphenyl-α-naphthylamine, alkylphenyl-β-naphthylamine and the like, and alkylphenyl-α-naphthylamine and alkylphenyl- β-naphthylamine is preferred.
The number of carbon atoms in the alkyl group of the alkylphenyl-α-naphthylamine and alkylphenyl-β-naphthylamine is preferably 1 to 30, but the solubility in mineral oil (A) and synthetic oil (B) is improved and , more preferably 1 to 20, still more preferably 4 to 16, still more preferably 6 to 14, from the viewpoint of further improving the effect of suppressing sludge deposition.

Diphenylamine (C12) is preferably a compound represented by the following general formula (c-1), more preferably a compound represented by the following general formula (c-2).

In general formulas (c-1) and (c-2), R ^x and R ^y are each independently substituted with an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 18 ring atoms. It is an alkyl group having 1 to 30 carbon atoms.
The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group.
In general formula (c-1), z1 and z2 are each independently an integer of 0 to 5, preferably 0 or 1, more preferably 1. In addition, when a plurality of R ^x and R ^y are present, the plurality of R ^x and R ^y may be the same or different from each other.

The number of carbon atoms in the alkyl group that can be selected for R ^x and R ^y is 1-30, preferably 1-20, more preferably 1-10.
Examples of the aryl group with which the alkyl group can be substituted include a phenyl group, a naphthyl group, and a biphenyl group, with the phenyl group being preferred.

Examples of alkyl groups possessed by alkylphenyl-naphthylamine and alkyl groups which may be possessed by diphenylamine include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, hexadecyl group, octadecyl group, nonadecyl group, icosyl group, tetracosyl group and the like.

In the lubricating oil composition of one aspect of the present invention, from the viewpoint of suppressing the generation of deterioration products, further improving the effect of suppressing sludge deposition, and providing a lubricating oil composition having excellent oxidation stability, amine-based The content of the antioxidant (C1) in terms of nitrogen atoms is preferably 50 to 3000 mass ppm, more preferably 100 to 2000 mass ppm, based on the total amount (100 mass%) of the lubricating oil composition. It is preferably 120 to 1500 ppm by mass, more preferably 150 to 1000 ppm by mass.

[Antioxidants other than amine antioxidant (C1)]
The antioxidant (C) may also contain antioxidants other than the amine-based antioxidant (C1) described above. Phenolic antioxidants are preferred as such antioxidants.

Phenolic antioxidants include, for example, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4,6-tri-t- Butylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2,6-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl- 4-(N,N-dimethylaminomethyl)phenol, 2,6-di-t-amyl-4-methylphenol, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) Monocyclic phenolic compounds such as propionate, 4,4′-methylenebis(2,6-di-t-butylphenol), 4,4′-isopropylidenebis(2,6-di-t-butylphenol), 2, 2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 4,4'-bis(2-methyl-6-t-butylphenol ), 2,2′-methylenebis(4-ethyl-6-t-butylphenol), and 4,4′-butylidenebis(3-methyl-6-t-butylphenol).

In the lubricating oil composition of one aspect of the present invention, the content of the phenolic antioxidant with respect to 100 parts by mass of the amine antioxidant (C1) is preferably 0 to 100 parts by mass, more preferably 0 to 60 parts by mass. parts by mass, more preferably 0 to 40 parts by mass.

<Phosphorus compound (D)>
From the viewpoint of improving wear resistance, the lubricating oil composition of one embodiment of the present invention further includes a neutral phosphate (D1), an acidic phosphate (D2), and an amine salt of an acidic phosphate (D3). , and sulfur-phosphorus compounds (D4) preferably contains one or more phosphorus compounds (D).
From the viewpoint of further improving rust resistance, it is preferable that component (D) contains one or more selected from component (D1) and component (D3). In addition, from the viewpoint of achieving both oxidation stability and wear resistance with a relatively small addition amount, it is preferable to contain one or more selected from component (D3) and component (D4).

In the lubricating oil composition of one aspect of the present invention, the content of component (D) in terms of phosphorus atoms is based on the total amount (100% by mass) of the lubricating oil composition, preferably 10 to 1600 mass ppm, more It is preferably 20 to 1200 mass ppm, more preferably 50 to 1000 mass ppm, still more preferably 100 to 800 mass ppm, and particularly preferably 150 to 600 mass ppm. When using one or more selected from component (D3) and component (D4), the content in terms of the phosphorus atom is based on the total amount (100% by mass) of the lubricating oil composition, preferably 10 It can be up to 50 mass ppm, more preferably 10 to 30 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the content of component (D) is based on the total amount (100% by mass) of the lubricating oil composition, preferably 0.01 to 2.0% by mass, more It is preferably 0.02 to 1.5% by mass, more preferably 0.05 to 1.0% by mass, and even more preferably 0.10 to 0.70% by mass. When one or more selected from component (D3) and component (D4) is used, the content of component (D) is preferably 0.1% based on the total amount (100% by mass) of the lubricating oil composition. 01 to 1.0 mass ppm, more preferably 0.01 to 0.2 mass ppm, more preferably 0.01 to 0.05 mass ppm.

[Neutral phosphate ester (D1)]
The neutral phosphate (D1) is preferably a compound (D11) represented by the following general formula (d1-1).

In general formula (d1-1), R ^D1 to R ^D3 are each independently an alkyl group having 1 to 18 carbon atoms (preferably 3 to 18), or an alkyl group having 1 to 18 carbon atoms (preferably 3 to 12 ) is an aryl group having 6 to 18 ring carbon atoms substituted with an alkyl group.
Examples of alkyl groups having 1 to 18 carbon atoms that can be selected as R ^D1 to R ^D3 include methyl group, ethyl group, propyl group (n-propyl group, isopropyl group), butyl group (n-butyl group, s -butyl group, t-butyl group, isobutyl group), pentyl group, hexyl group, 2-ethylhexyl 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 and the like.
These alkyl groups may be straight-chain alkyl groups or branched-chain alkyl groups.

Examples of the aryl group having 6 to 18 ring carbon atoms include phenyl group, naphthyl group, anthryl group, phenanthryl group, biphenyl group, terphenyl group, phenylnaphthyl group and the like, with phenyl group being preferred.
The "aryl group substituted with an alkyl group having 1 to 18 carbon atoms" which can be selected as R ^D1 to R ^D3 includes at least one hydrogen atom bonded to the ring-forming carbon atom of the above-mentioned aryl group. One is the group substituted by the above-mentioned alkyl group having 1 to 18 carbon atoms.

Compound (D11) is more preferably compound (D12) represented by general formula (d1-2) below.

In general formula (d1-2), R ^D11 to R ^D13 each independently represent an alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group include the same alkyl groups that can be selected for R ^D11 to R ^D13 described above.
The number of carbon atoms in the alkyl group that can be selected as R ¹¹ to R ¹³ is 1 to 18, preferably 3 to 12, more preferably 3 to 12, from the viewpoint of obtaining a lubricating oil composition with improved rust prevention properties. is 3 to 8, more preferably 3 to 6, even more preferably 3.
In addition, p1 to p3 are each independently an integer of 1 to 5, preferably an integer of 1 to 2, and more preferably 1.

[Acidic phosphate (D2)]
The acidic phosphate (D2) is preferably one or more selected from compounds represented by the following general formula (d2-1) and compounds represented by the following general formula (d2-2). .

In general formulas (d2-1) and (d2-2), R ^a and R ^b each independently represent an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group include the same alkyl groups having 1 to 12 carbon atoms among the alkyl groups that can be selected for R ^D1 to R ^D3 described above.
The number of carbon atoms in the alkyl group that can be selected for R ^a and R ^b is preferably 3-10, more preferably 6-10, and still more preferably 8-10.
R ^a and R ^b in general formula (d2-1) may be the same or different from each other.

[Amine salt of acidic phosphate (D3)]
The amine salt of acidic phosphoric acid ester (D3) is selected from the amine salt of the compound represented by the general formula (d2-1) and the amine salt of the compound represented by the general formula (d2-2). It is preferable that it is one or more kinds.
The amine that forms the amine salt is preferably a compound represented by the following general formula (d3). In addition, the said amine may be used independently and may use 2 or more types together.

In the general formula (d3), q represents an integer of 1-3.
Each R ^c is independently an alkyl group having 6 to 18 carbon atoms, an alkenyl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 ring carbon atoms, an arylalkyl group having 7 to 18 carbon atoms, or an arylalkyl group having 7 to 18 carbon atoms. It is a hydroxyalkyl group having 6 to 18 carbon atoms, preferably an alkyl group having 6 to 18 carbon atoms.
In addition, when a plurality of R ^c are present, the plurality of R ^c may be the same or different from each other.

Examples of the alkyl group that can be selected as R ^c include hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group and the like.
The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group.
The number of carbon atoms in the alkyl group that can be selected as R ^c is 6 to 18, preferably 7 to 16, more preferably 8 to 15, and still more preferably 10 to 13.

Examples of the alkenyl group that can be selected as R ^c include hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, hexadecenyl group and octadecenyl group. be done.
The alkenyl group may be a straight-chain alkenyl group or a branched-chain alkenyl group.
The alkenyl group that can be selected as R ^c has 6 to 18 carbon atoms, preferably 7 to 16 carbon atoms, more preferably 8 to 15 carbon atoms, and still more preferably 10 to 13 carbon atoms.

Examples of the aryl group that can be selected as R ^c include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group, a terphenyl group, and a phenylnaphthyl group.
The aryl group that can be selected as R ^c has 6 to 18 carbon atoms, preferably 6 to 16 carbon atoms, and more preferably 6 to 14 carbon atoms.

Examples of the arylalkyl group that can be selected as R ^c include groups in which a hydrogen atom of the above-mentioned alkyl group is substituted with the above-mentioned aryl group, and specific examples include a phenylmethyl group, a phenylethyl group, and the like. be done.
The arylalkyl group that can be selected as R ^c has 7 to 18 carbon atoms, preferably 7 to 16 carbon atoms, and more preferably 8 to 14 carbon atoms.

Examples of the hydroxyalkyl group that can be selected as R ^c include groups in which the hydrogen atoms of the above-mentioned alkyl groups are substituted with hydroxy groups, and specifically, hydroxyhexyl group, hydroxyoctyl group, and hydroxydodecyl group. , hydroxytridecyl group, and the like.
The hydroxyalkyl group that can be selected as R ^c has 6 to 18 carbon atoms, preferably 7 to 16 carbon atoms, more preferably 8 to 15 carbon atoms, and still more preferably 10 to 13 carbon atoms.

[Sulfur-phosphorus compound (D4)]
Examples of sulfur-phosphorus compounds (D4) include monothiophosphates, dithiophosphates, trithiophosphates, amine salts of monothiophosphates, amine salts of dithiophosphates, monothiophosphites, dithiophosphites, and trithiophosphates. Examples include phosphites, and among these, dithiophosphates are preferred.
From the viewpoint of improving wear resistance, among dithiophosphates, dithiophosphates having a terminal carboxyl group or an ester residue are preferred. Since the sulfur-phosphorus compound (D4) has a carboxyl group or an ester residue at its end, the polarity becomes high, so in this embodiment in which the above-described specific ester synthetic base oil (A) is used as the base oil Also, it becomes easier to exhibit the function as an extreme pressure agent.

式（ｄ４）において、Ｒ^ｄは炭素数１～８の直鎖又は分岐のアルキレン基を表し、Ｒ^ｅ及びＲ^ｆはそれぞれ独立に炭素数１～２０の炭化水素基を表す。またＲ^ｇは水素原子又は炭素数１～１０の炭化水素基を表す。Specific examples of the dithiophosphate having a terminal carboxyl group or an ester residue include compounds represented by the following general formula (d4).

In formula (d4), R ^d represents a linear or branched alkylene group having 1 to 8 carbon atoms, and R ^e and R ^f each independently represent a hydrocarbon group having 1 to 20 carbon atoms. ^Rg represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

In formula (d4), R ^d is preferably a linear or branched alkylene group having 1 to 8 carbon atoms from the viewpoint of improving solubility in the base oil, and a linear or branched alkylene group having 2 carbon atoms. An alkylene group having up to 4 carbon atoms is more preferable, and an alkylene group having 2 carbon atoms or a branched alkylene group having 3 to 4 carbon atoms is even more preferable. Specifically, -CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )-, -CH ₂ CH(CH ₂ CH ₃ )-, -CH ₂ CH(CH ₃ )CH ₂ -, and -CH ₂ CH(CH ₂ CH ₂ CH ₃ )- is preferred, and -CH ₂ CH ₂ -, -CH ₂ CH(CH ₃ )-, -CH ₂ CH(CH ₃ )CH ₂ - is more preferred, and -CH ₂ CH ₂ - and -CH ₂ CH(CH ₃ )- are more preferred.

Each of R ^e and R ^f is preferably a linear or branched alkyl group having 1 to 8 carbon atoms from the viewpoint of improving the solubility in the base oil while improving the extreme pressure performance. is more preferably an alkyl group having 3 to 6 carbon atoms. Specifically, it is selected from the group consisting of propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, hexyl, 2-ethylbutyl, 1-methylpentyl, 1,3-dimethylbutyl and 2-ethylhexyl groups. Among these, isopropyl, isobutyl and t-butyl are more preferred.

Further, R ^g is preferably a hydrogen atom or a linear or branched C 1-4 alkyl group from the viewpoint of improving extreme pressure performance and solubility in base oil. Specifically, hydrogen atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl and t-butyl groups are preferred, and among these, hydrogen atom, methyl group and ethyl group are more preferred.

<Other lubricating oil additives>
The lubricating oil composition of one aspect of the present invention may contain lubricating oil additives other than the components (B) to (D) as long as the effects of the present invention are not impaired.
Examples of such lubricating oil additives include rust preventives, detergent dispersants, viscosity index improvers, antifoaming agents, friction modifiers, and metal deactivators.
These lubricating oil additives may be used alone or in combination of two or more.

When these lubricating oil additives are blended, the content of each of the lubricating oil additives is appropriately adjusted according to the type of additive within a range that does not impair the effects of the present invention, but the lubricating oil Based on the total amount (100% by mass) of the composition, it is usually 0.001 to 10% by mass, preferably 0.005 to 5% by mass, more preferably 0.01 to 2% by mass.

A lubricating oil composition obtained by blending an alkenyl succinic acid ester with a base oil such as PAG or POE also causes a decrease in water separability.
However, since the lubricating oil composition of the present invention contains the mineral oil (A) that has good compatibility with the alkenyl succinate ester, it is possible to effectively express the rust prevention property of the alkenyl succinate ester. can. Moreover, even if an alkenyl succinic acid ester is blended, a lubricating oil composition having good water separability can be obtained.

In the lubricating oil composition of one aspect of the present invention, the content of the alkenyl succinate ester is based on the total amount (100% by mass) of the lubricating oil composition, preferably 0.001 to 5.0% by mass, and more It is preferably 0.005 to 2.0% by mass, more preferably 0.01 to 1.0% by mass, and even more preferably 0.02 to 0.50% by mass.

In addition, the lubricating oil composition of one aspect of the present invention preferably does not substantially contain a metal atom-containing compound, from the viewpoint of suppressing sludge that occurs with long-term use in a high-temperature environment.
Here, the metal atoms contained in the "metal atom-containing compound" refer to alkali metal atoms, alkaline earth atoms, and transition metal atoms.

In the present specification, the phrase "substantially does not contain a metal atom-containing compound" is a rule that denies the inclusion of a metal atom-containing compound for a given purpose, and the metal atom-containing compound is an impurity. It is not a provision that denies even the case of inclusion.
However, it is preferable that the content of the metal atom-containing compound contained as an impurity is as low as possible.

In the lubricating oil composition of one aspect of the present invention, the content of metal atoms is the total amount of the lubricating oil composition (100 mass% ) basis, preferably less than 100 ppm by mass, more preferably less than 50 ppm by mass, even more preferably less than 10 ppm by mass, and even more preferably less than 5 ppm by mass.
As used herein, the content of metal atoms means a value measured according to JPI-5S-38-92.

[Various physical properties of the lubricating oil composition]
The kinematic viscosity at 40° C. of the lubricating oil composition of one aspect of the present invention is preferably 5 to 300 mm ² /s, more preferably 10 to 200 mm ² /s, still more preferably 15 to 100 mm ² /s.

The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 90 or higher, more preferably 100 or higher, even more preferably 105 or higher, and even more preferably 110 or higher.

Sludge after 960 hours from the start of the test in an environment of 120 ° C., measured according to the oxidation stability test (Dry-TOST method) of ASTM D7873 for the lubricating oil composition of one embodiment of the present invention The amount produced is preferably 1.0 mg/100 ml or less, more preferably 0.7 mg/100 ml or less, and even more preferably 0.5 mg/100 ml or less.
The amount of sludge produced is a value measured using a membrane filter having an average pore size of 1.0 μm according to ASTM D7873.

RPVOT after 960 hours from the start of the test in an environment of 120 ° C., measured according to the oxidation stability test (Dry-TOST method) of ASTM D7873 for the lubricating oil composition of one embodiment of the present invention The residual rate is preferably 65% or higher, more preferably 70% or higher, and even more preferably 72% or higher.
The RPVOT residual rate is a value calculated from the following formula.
・ [RPVOT survival rate] (%) = [RPVOT time of sample after test] / [RPVOT time of sample before test] x 100

When the lubricating oil composition of one embodiment of the present invention was subjected to a water separation test at a temperature of 54 ° C. in accordance with JIS K2520, the demulsification degree representing the time until the emulsified layer reached 3 mL , preferably 15 minutes or less, more preferably 10 minutes or less, and even more preferably 5 minutes or less.

The lubricating oil composition of one aspect of the present invention preferably has a traction coefficient of 0.020 or less, more preferably 0.018 or less, as measured under the measurement conditions of Examples described later.

[Use of lubricating oil composition, lubrication method]
The lubricating oil composition of the present invention is used in turbomachinery, compressors (excluding refrigerators), hydraulic equipment, or machine tools.
Specifically, the lubricating oil composition of one aspect of the present invention is used for lubricating turbomachinery such as pumps, vacuum pumps, blowers, turbocompressors, steam turbines, nuclear turbines, gas turbines, hydroelectric turbines, and the like. Lubricating oil for turbo machinery (pump oil, turbine oil, etc.); Bearing oil, gear oil, and control system hydraulic oil used for lubricating compressors such as rotary compressors and reciprocating compressors; Hydraulic oil used in hydraulic equipment Hydraulic oil; lubricating oil for machine tools used in hydraulic units of machine tools; and the like.

That is, the present application can also provide the following usage method [1].
[1] A lubricating oil containing a mineral oil (A) and a synthetic oil (B) containing a polyalkylene glycol (B1) and a polyol ester (B2), wherein the content of the mineral oil (A) is 5 to 95% by mass. A method of using the lubricating oil composition wherein the composition is used in turbomachinery, compressors, hydraulic equipment, or machine tools.
The specific configuration of the lubricating oil composition of the present invention, and specific examples of turbomachinery, compressors, hydraulic equipment, and machine tools are as described above.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Methods for measuring various physical property values]
(1) Kinematic viscosity and viscosity index Measured and calculated according to JIS K2283:2000.
(2) number average molecular weight (Mn)
Under the following measurement conditions, Mn in terms of standard polystyrene was measured according to the gel permeation chromatography (GPC) method.
(Measurement condition)
・ Gel permeation chromatograph device: “1260 type HPLC” manufactured by Agilent Co., Ltd.
- Standard sample: Polystyrene Column: Two "LF404" columns manufactured by Shodex Co., Ltd. were connected in order.
・Column temperature: 35°C
・Developing solvent: chloroform ・Flow rate: 0.3 mL/min
(3) Phosphorus atom and metal atom content Measured according to JPI-5S-38-92.
(4) Nitrogen atom content Measured according to JIS K2609.

Examples 1-7, Comparative Examples 1-5
Mineral oils, synthetic oils, amine antioxidants, phosphorus compounds, and other additives shown below are added in the blending amounts shown in Table 1, mixed well, and lubricating oil compositions (I) ~ (VII) and (i)-(v) were prepared respectively.
The details of each component used in the preparation of these lubricating oil compositions are as follows.

(mineral oil)
• "150N mineral oil": mineral oil classified in Group 2 of the API base oil category, 40°C kinematic viscosity = 30.6 mm ² /s, viscosity index = 104.
(synthetic oil)
- "PAG": H-(OCH(CH ₃ )CH ₂ ) _a -OC ₄ H ₉ , one end of which is butyl ether-capped polypropylene glycol (in general formula (b-1) A compound in which R 1 ^B1 is a hydrogen atom, R ^{2 B2} is a propylene group, R 2 ^B3 is an n-butyl group, and b is 1). 40° C. kinematic viscosity=37.2 mm ² /s, viscosity index=173, Mn=800.
• "POE": trimethylolpropane triester (perfect ester of trimethylolpropane and a carboxylic acid having 8 to 10 carbon atoms). 40° C. kinematic viscosity=19.6 mm ² /s, viscosity index=138.
(Amine antioxidant)
- "Naphthylamine": p-octylphenyl-α-naphthylamine, nitrogen atom content = 4.2% by mass.
- "Diphenylamine": bis(p-octylphenyl)amine, a compound in which R ^x and R ^y in the general formula (c-2) are octyl groups, nitrogen atom content = 3.6% by mass.
(Phosphorus compound)
- "Neutral phosphate": tris(p-isopropylphenyl) phosphate, p1 to p3 in the general formula (d1-2) are 1, R ^D11 to R ^D13 are isopropyl groups, and the isopropyl A compound in which the group is attached in the para position. Phosphorus atom content = 6.8% by weight.
- "acidic phosphate ester amine": an amine salt of a mixture of the compounds represented by the general formulas (d2-1) and (d2-2) and the compound represented by the general formula (d3) (R ^a and R ^b in general formulas (d2-1) and (d2-2) are alkyl groups having 8 or 10 carbon atoms, and R ^c in general formula (d3) is an alkyl group having 12 carbon atoms, q is 1 or 2). Phosphorus atom content = 4.8% by weight.
• Thiophosphate ester 1: 3-diisobutoxyphosphinothioylsulfanyl-2-methylpropanoic acid, phosphorus atom content = 9.3% by weight.
· Thiophosphate ester 2: ethyl-3-[{bis(1-methylethoxy)phosphinothioyl}thio]propionate, phosphorus atom content = 9.9 mass%
(other additives)
・"Rust inhibitor": Half ester of alkenyl succinic acid.
- "Antifoaming agent": Silicone antifoaming agent, acrylic antifoaming agent.

For each of the prepared lubricating oil compositions, various physical property values shown in Tables 1 and 2 were measured based on the methods described above, and the following tests were conducted to evaluate various properties of the lubricating oil composition. These results are shown in Tables 1 and 2.

(1) Oxidation stability test (Dry-TOST)
In accordance with the oxidation stability test (Dry-TOST) of ASTM D7873, the amount of sludge produced and the residual rate of RPVOT were measured in an environment of 120° C. after 960 hours from the start of the test.
The amount of sludge produced was measured according to ASTM D7873 using a membrane filter manufactured by Millipore with an average pore size of 1.0 μm.
Also, the RPVOT residual rate was calculated from the following formula.
・ [RPVOT survival rate] (%) = [RPVOT time of sample after test] / [RPVOT time of sample before test] x 100

(2) Water Separability Test A water separation test was conducted at a temperature of 54° C. according to JIS K2520, and the time (demulsification degree, unit: minutes) for the emulsified layer to reach 3 mL was measured.

(3) Measurement of traction coefficient Using an EHD oil film measuring instrument (manufactured by PCS Instrumental), the traction coefficient was measured under the following measurement conditions.
・Disk: 46mm diameter, SAE AISI52100 steel ・Ball: 19mm diameter, SAE AISI52100 steel ・Load: 20N
・Rolling speed: 2.0m/s
・Oil temperature: 60℃
・Slip rate: 10%

(4) Abrasion resistance test Using an FZG gear tester, the load was increased stepwise according to the regulations in accordance with ISO 14635-1, and the load stage at which scoring occurred was evaluated. A higher load stage indicates better scoring resistance.

The lubricating oil compositions prepared in Examples 1 to 7 were excellent in oxidation stability, highly effective in suppressing sludge deposition, and excellent in water separation. In addition, the traction coefficient was low, and an effect of improving wear resistance was also observed.
On the other hand, the lubricating oil composition prepared in Comparative Example 1 was inferior in oxidation stability, resulting in a large amount of sludge formation and a low residual RPVOT rate as compared with the Examples. Moreover, it is also insufficient from the viewpoint of wear resistance.
In addition, the lubricating oil compositions prepared in Comparative Examples 2, 3, 4 and 5 have good oxidation stability and wear resistance, but have poor water separation properties. It was particularly bad, and the result was that the amount of sludge produced was considerably large.

Claims (10)

A lubricating oil composition containing a mineral oil (A) and a synthetic oil (B) containing a polyalkylene glycol (B1) represented by the following general formula (b-1) and a polyol ester (B2),
The content of the component (B1) is 1.0 to 70% by mass based on the total amount of the lubricating oil composition,
The content of the component (B2) is 2.0 to 90% by mass based on the total amount of the lubricating oil composition,
The content of the mineral oil (A) is 5 to 95% by mass based on the total amount of the lubricating oil composition,
A lubricating oil composition for use in turbomachinery, compressors, hydraulic equipment or machine tools.
R ^B1 -[(OR ^B2 ) _a -OR ^B3 ] _b (b-1)
(In the above general formula (b-1),
a is a number of 1 or more,
b is 1;
R ^B1 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms,
R ^B2 is an alkylene group having 3 or 4 carbon atoms,
R ^B3 is a propyl group, butyl group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group, methylcyclohexyl group, ethylcyclohexyl group, propylcyclohexyl group, dimethylcyclohexyl group, phenyl group, naphthyl group, benzyl group, phenylethyl group; , methylbenzyl, phenylpropyl or phenylbutyl. ) The lubricating oil composition according to claim 1, wherein the content ratio [(B1)/(B2)] of the component (B1) and the component (B2) is 10/90 to 80/20 in mass ratio. The content ratio of component (A) to the total content of component (B1) and component (B2) [(A)/((B1)+(B2))] is 0.05 to 19.0 by mass. 3. The lubricating oil composition according to claim 1 or 2, which is 0. The lubricating oil composition according to any one of claims 1 to 3, further comprising an antioxidant (C) containing an amine antioxidant (C1). The lubricating oil composition according to claim 4, wherein the content of component (C1) in terms of nitrogen atoms is 50 to 3000 mass ppm based on the total amount of the lubricating oil composition. Furthermore, at least one phosphorus compound (D ), the lubricating oil composition according to any one of claims 1 to 5. The lubricating oil composition according to claim 6, wherein the content of component (D) in terms of phosphorus atoms is 10 to 1600 mass ppm based on the total amount of the lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 7, wherein the content of metal atoms is less than 100 mass ppm based on the total amount of the lubricating oil composition. According to JIS K2520, when a water separation test is performed at a temperature of 54 ° C., the demulsification degree, which represents the time until the emulsified layer reaches 3 mL, is 15 minutes or less. The lubricating oil composition according to claim 1. A method of using a lubricating oil composition according to any one of claims 1 to 9 in turbomachinery, compressors, hydraulic equipment or machine tools.