JP2008266367A - Lubricating oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition that achieves both suppression of catalyst poisoning and enhancement of abrasion resistance in an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst. <P>SOLUTION: The lubricating oil composition comprises a lubricating base oil and at least one phosphorous compound selected from among metal salts of phosphorous compounds represented by formulae (1) and (2) with the content thereof of 0.005-0.5 mass% in terms of the phosphorus element based on the whole amount of the lubricating oil composition. In the formulae, R<SP>1</SP>and R<SP>4</SP>are each a 1-30C hydrocarbon group or a group containing at least one selected from among sulfur, oxygen and nitrogen; R<SP>2</SP>, R<SP>3</SP>, R<SP>5</SP>and R<SP>6</SP>are each a hydrogen atom, a 1-30C hydrocarbon group or a group containing at least one selected from among sulfur, oxygen and nitrogen; and m and n are each 0 or 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition.

  Conventionally, lubricating oil is used for an internal combustion engine, an automatic transmission, grease, and the like in order to make the operation smooth. Among these lubricating oils, the lubricating oil for internal combustion engines (also referred to as “engine oil”) has high performance due to the high performance, high output, and severe operating conditions of the internal combustion engine. It is becoming required.

In the conventional lubricating oil for internal combustion engines, various additives such as an antiwear agent, a metallic detergent, an ashless dispersant, and an antioxidant are blended in order to satisfy the above-mentioned required performance. Among them, zinc dialkyldithiophosphate has a function as an antiwear agent or an antioxidant, and is therefore used as an indispensable additive for lubricating oil for internal combustion engines (for example, see Patent Document 1 below).
Japanese Patent Laid-Open No. 08-302378

  However, the conventional lubricating oil composition containing zinc dialkyldithiophosphate has room for improvement in the following points.

  That is, the zinc dialkyldithiophosphate is a factor that poisons the three-way catalyst and the oxidation catalyst that are used as the exhaust gas purification catalyst. Since this poisoning is considered to be caused by the evaporation of phosphorus in the process of use and inclusion in the exhaust gas, the content of zinc dialkyldithiophosphate in the lubricating oil for internal combustion engines from the viewpoint of suppressing catalyst poisoning It is desirable to reduce However, merely reducing the content of zinc dialkyldithiophosphate will not reduce the wear resistance, which is the original purpose of adding zinc dialkyldithiophosphate, and therefore cannot be a fundamental solution.

  The present invention has been made in view of the above-described problems of the prior art, and in an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst, it is possible to achieve both suppression of catalyst poisoning and improvement of wear resistance. It is an object to provide a lubricating oil composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above problems can be solved by a lubricating oil composition containing a specific amount of a phosphorus compound having a specific structure, and to complete the present invention. It came.

［一般式（１）中、Ｒ^１は炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、Ｒ^２及びＲ^３は同一でも異なっていてもよく、それぞれ水素原子、炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、ｍは０又は１を示す。］

［一般式（２）中、Ｒ^４は炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、Ｒ^５及びＲ^６は同一でも異なっていてもよく、水素原子、炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、ｎは０又は１を示す。］ That is, the present invention provides at least one selected from a lubricating base oil, a metal salt of a phosphorus compound represented by the following general formula (1), and a metal salt of a phosphorus compound represented by the following general formula (2). A metal salt of the phosphorus compound, and the content of the metal salt of the phosphorus compound is 0.005 to 0.5% by mass in terms of phosphorus element based on the total amount of the lubricating oil composition, Provided is a lubricating oil composition used for an internal combustion engine equipped with a three-way catalyst.

[In General Formula (1), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ² and R ³ may be the same or different. And each represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a group containing at least one selected from sulfur, oxygen, and nitrogen, and m represents 0 or 1. ]

[In General Formula (2), R ⁴ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ⁵ and R ⁶ may be the same or different. It may be a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and n represents 0 or 1. ]

  In the present invention, the phosphorus concentration in the lubricating oil composition is preferably 0.01 to 0.10% by mass in terms of phosphorus based on the total amount of the lubricating oil composition. As a result, it is possible to more reliably achieve both the suppression of the poisoning of the oxidation catalyst or the three-way catalyst and the improvement of the wear resistance.

  According to the lubricating oil composition of the present invention, compared with the conventional lubricating oil using zinc dialkyldithiophosphate, in an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst, it is possible to suppress catalyst poisoning and wear resistance. Improvements can be achieved at a higher level.

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

  The lubricating base oil contained in the lubricating oil composition of the present invention is not particularly limited, and those used for ordinary lubricating oils can be used. Specifically, a mineral oil base oil, a synthetic oil base oil, or a mixture of two or more kinds of lubricant base oils selected from these can be used.

  Specifically, as the mineral base oil, the lube oil fraction obtained by distilling the atmospheric residue obtained by atmospheric distillation of the crude oil is subjected to solvent removal, solvent extraction, and hydrogenation. Examples include those refined by one or more treatments such as decomposition, solvent dewaxing, hydrorefining, etc., or base oils produced by isomerizing wax isomerized mineral oil, GTL wax (gas-tuly wax) it can.

  Specific examples of synthetic oils include polybutene or hydrides thereof; poly-α-olefins such as 1-octene oligomers and 1-decene oligomers or hydrides thereof; ditridecyl glutarate, di-2-ethylhexyl. Diesters such as adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate; polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate And aromatic synthetic oils such as alkylnaphthalene and alkylbenzene, or a mixture thereof.

The kinematic viscosity of the lubricating base oil is not particularly limited, but the kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 50 mm ² / s or less, more preferably 40 mm ² / s or less, and even more preferably 20 mm ² / s or less. Particularly preferably, it is 10 mm ² / s or less. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 50 mm ² / s, the low-temperature viscosity characteristics tend to be insufficient. The kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the lubricating base oil is less than 1 mm ² / s, oil film formation at the lubrication site tends to be insufficient and the lubricity tends to decrease, and the evaporation loss of the lubricating base oil The amount tends to increase.

  The viscosity index of the lubricating base oil is not particularly limited, but is preferably 80 or more from the viewpoint of low temperature viscosity characteristics. Further, from the viewpoint of obtaining excellent viscosity characteristics in a wide temperature range from low temperature to high temperature, the viscosity index of the lubricating base oil is more preferably 100 or more, further preferably 110 or more, particularly 120 or more. It is preferable that

  The sulfur content of the lubricating base oil is not particularly limited, but is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, 0.005% by mass or less, Particularly preferred are those which do not substantially contain (0.001% by mass or less). The “sulfur content” in the present invention is JIS K 2541-4 “radiation type excitation method” (usually in the range of 0.01 to 5% by mass) or JIS K 2541-5 “bomb type mass method”. , Annex (normative), inductively coupled plasma emission method "(usually 0.05% by mass or more) means a value measured.

  The total aromatic content of the lubricating base oil is not particularly limited, but is preferably 30% by mass or less, more preferably 15% by mass or less, still more preferably 5% by mass or less, and particularly preferably 2% by mass or less. It is. When the total aromatic content of the lubricating base oil exceeds 30% by mass, the oxidation stability tends to be insufficient. The “total aromatic content” as used in the present invention means an aromatic fraction content measured in accordance with ASTM D2549. Usually, this aromatic fraction includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene, and alkylated products thereof, compounds in which four or more benzene rings are condensed, or pyridines, quinolines, phenols, naphthols, etc. Examples include compounds having heteroaromatics.

［一般式（１）中、Ｒ^１は炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、Ｒ^２及びＲ^３は同一でも異なっていてもよく、それぞれ水素原子、炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、ｍは０又は１を示す。］

［一般式（２）中、Ｒ^４は炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、Ｒ^５及びＲ^６は同一でも異なっていてもよく、水素原子、炭素数１〜３０の炭化水素基又は硫黄、酸素及び窒素から選ばれる少なくとも１種を含有する基を示し、ｎは０又は１を示す。］ The lubricating oil composition of the present invention includes a metal salt of a phosphorus compound represented by the following general formula (1) and a metal salt of a phosphorus compound represented by the following general formula (2) in addition to the above lubricating base oil. The metal salt of the at least 1 sort (s) of phosphorus compound chosen from these is contained.

[In General Formula (1), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ² and R ³ may be the same or different. And each represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a group containing at least one selected from sulfur, oxygen, and nitrogen, and m represents 0 or 1. ]

[In General Formula (2), R ⁴ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ⁵ and R ⁶ may be the same or different. It may be a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and n represents 0 or 1. ]

Specific examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R ^{1 to} R ⁶ in the general formulas (1) and (2) include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkyl substitution. Mention may be made of cycloalkyl groups, aryl groups, alkyl-substituted aryl groups, and arylalkyl groups.

  Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like. Group, hexadecyl group, heptadecyl group, octadecyl group and other alkyl groups (these alkyl groups may be linear or branched).

  As said cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, can be mentioned, for example. Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, Examples thereof include an alkylcycloalkyl group having 6 to 11 carbon atoms such as a dimethylcycloheptyl group, a methylethylcycloheptyl group, and a diethylcycloheptyl group (the substitution position of the alkyl group with the cycloalkyl group is also arbitrary).

  Examples of the alkenyl group include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, An alkenyl group such as an octadecenyl group (these alkenyl groups may be linear or branched, and the position of the double bond is also optional).

  As said aryl group, aryl groups, such as a phenyl group and a naphthyl group, can be mentioned, for example. Examples of the alkylaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, and decylphenyl. A C7-C18 alkylaryl group such as a group, undecylphenyl group, dodecylphenyl group, etc. (the alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary) Can do.

  Examples of the arylalkyl group include arylalkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group. It may be branched).

When R ^{1 to} R ⁶ are a hydrocarbon group having 1 to 30 carbon atoms, R ^{1 to} R ⁶ are preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, and more Preferably it is a C3-C18 alkyl group, More preferably, it is a C4-C12 alkyl group.

^Further, as a specific example of R 1 to R ⁶ is a group containing at least one selected from sulfur, oxygen and nitrogen, RO- _{(AO) n} -, a group represented by, R- (S) a group represented by _n- R- (wherein R represents a hydrocarbon group, A represents an alkylene group, and n represents an integer of 1 or more).

  The metal salt of the phosphorus compound represented by the general formula (1) or (2) includes a metal compound, a metal hydroxide, a metal carbonate, a phosphorus compound represented by the general formula (1) or (2), It can be obtained by neutralizing part or all of the remaining acidic hydrogen by the action of a metal base such as metal chloride.

  Specific examples of the metal in the metal base include alkali metals such as lithium, sodium, potassium and cesium, alkaline earth metals such as calcium, magnesium and barium, zinc, copper, iron, lead, nickel, silver and manganese. And heavy metals such as molybdenum. Among these, alkaline earth metals such as calcium and magnesium, molybdenum and zinc are preferable, and zinc is particularly preferable.

［式中、Ｒは一般式（２）中のＲ^４〜Ｒ^６と同一の定義内容を示す。］ In addition, the structure of the metal salt of the phosphorus compound differs depending on the valence of the metal or the number of OH groups of the phosphorus compound, and therefore the structure of the metal salt of the phosphorus compound is not limited at all. For example, when 1 mol of zinc oxide and 2 mol of phosphoric diester (compound having one OH group) are reacted, a compound having a structure represented by the following formula (3) is considered to be obtained as a main component. Is also considered to exist.

[In formula, R shows the same definition content as R < ⁴ > -R < ⁶ > in General formula (2). ]

［式中、Ｒは一般式（２）中のＲ^４〜Ｒ^６と同一の定義内容を示す。］ Further, for example, when 1 mol of zinc oxide and 1 mol of phosphoric acid monoester (a compound having two OH groups) are reacted, it is considered that a compound having a structure represented by the following formula (4) is obtained as a main component. Polymerized molecules are also thought to exist.

[In formula, R shows the same definition content as R < ⁴ > -R < ⁶ > in General formula (2). ]

  In the present invention, the metal salt of the phosphorus compound represented by the general formula (1) or (2) may be used alone or in combination of two or more.

In the present invention, as the metal salt of the phosphorus compound represented by the general formula (1) or (2),
A salt of a phosphite diester having two alkyl or aryl groups having 3 to 18 carbon atoms and zinc, calcium or molybdenum;
A salt of a monoester of phosphoric acid having one alkyl group or aryl group having 3 to 18 carbon atoms and zinc, calcium or molybdenum;
A diester of phosphoric acid having two alkyl groups or aryl groups having 3 to 18 carbon atoms and a salt of zinc, calcium or molybdenum;
A salt of (hydrocarbyl) phosphonous acid and zinc or calcium having one alkyl group or aryl group having 1 to 18 carbon atoms;
A salt of (hydrocarbyl) phosphonous acid monoester having two alkyl or aryl groups having 1 to 18 carbon atoms and zinc, calcium or molybdenum;
A salt of (hydrocarbyl) phosphonic acid having one alkyl group or aryl group having 1 to 18 carbon atoms and zinc or calcium; and a (hydrocarbyl) phosphonic acid monoester having two alkyl groups or aryl groups having 1 to 18 carbon atoms Salts of esters with zinc or calcium or molybdenum are preferred.

  The above (hydrocarbyl) (sub) phosphonic acid, metal salt thereof, (hydrocarbyl) (sub) phosphonic acid monoester, metal salt thereof, and (hydrocarbyl) (sub) phosphonic acid diester have oil solubility and extreme pressure. Therefore, the total carbon number of the hydrocarbon group is preferably 12 to 30, more preferably 14 to 24, and still more preferably 16 to 20.

  In the lubricating oil composition of the present invention, the content of the metal salt of the phosphorus compound represented by the general formula (1) or (2) is 0.005 to 0 in terms of phosphorus element based on the total amount of the lubricating oil composition. 0.5% by mass, preferably 0.005 to 0.2% by mass, more preferably 0.005 to 0.1% by mass, and still more preferably 0.005 to 0.08% by mass. By controlling the content of the metal salt of the phosphorus compound represented by the general formula (1) or (2) within the above range, in an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst, it is possible to suppress catalyst poisoning and It becomes possible to achieve both improved wear. In addition, if the content of the metal salt of the phosphorus compound represented by the general formula (1) or (2) is less than the lower limit, abrasion resistance becomes insufficient, and if the content exceeds the upper limit, the evaporation of phosphorus The amount increases and catalyst poisoning cannot be sufficiently suppressed.

  In addition to the metal salt of the phosphorus compound represented by the general formula (1) or (2), the lubricating oil composition of the present invention can contain phosphorus such as zinc dialkyldithiophosphate as long as the effects of the present invention are not impaired. The content of the phosphorus-containing additive other than the metal salt of the phosphorus compound represented by the general formula (1) or (2) may be 0.1% based on the total amount of the composition. It is preferably at most mass%, more preferably at most 0.05 mass%, further preferably at most 0.02 mass%.

  Furthermore, the phosphorus concentration in the lubricating oil composition is preferably 0.01 to 0.10% by mass in terms of phosphorus element, based on the total amount of the lubricating oil composition, and 0.01 to 0.08% by mass. More preferably. When the phosphorus concentration in the lubricating oil composition exceeds the upper limit, the amount of phosphorus evaporation increases and the catalyst poisoning suppression effect tends to decrease.

  The lubricating oil composition of the present invention can contain various additives described below in addition to the lubricating base oil and the metal salt of the phosphorus compound represented by the general formula (1) or (2).

  The lubricating oil composition of the present invention preferably further contains a metallic detergent in order to further improve its acid neutralization properties, high temperature cleanability and wear resistance.

  Examples of the metal detergent include alkali metal sulfonate or alkaline earth metal sulfonate, alkali metal phenate or alkaline earth metal phenate, alkali metal salicylate or alkaline earth metal salicylate, alkali metal phosphonate or alkaline earth metal phosphonate, or These mixtures etc. are mentioned.

  More specifically, the alkali metal or alkaline earth metal sulfonate is an alkali metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 100 to 1500, preferably 200 to 700, for example. Alternatively, alkaline earth metal salts, particularly magnesium salts and / or calcium salts are preferably used. Specific examples of the alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids.

  As the petroleum sulfonic acid, those obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil or so-called mahoganic acid which is produced as a by-product when white oil is produced is used. As the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group obtained as a by-product from an alkylbenzene production plant that is a raw material for detergents or by alkylating polyolefin with benzene is used as a raw material. , Sulfonated ones thereof, sulfonated ones of dinonylnaphthalene and the like are used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but usually fuming sulfuric acid or sulfuric acid is used.

  More specifically, the alkali metal or alkaline earth metal phenate is an alkylphenol having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, and the alkylphenol and element. Alkyl metal salts or alkaline earth metal salts, especially magnesium salts and / or calcium salts of Mannich reaction products of alkylphenols obtained by reacting sulfur with alkylphenols obtained by reacting this alkylphenol with formaldehyde are preferably used. .

  More specifically, the alkali metal or alkaline earth metal salicylate is an alkali metal salt of an alkyl salicylic acid having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Alternatively, alkaline earth metal salts, particularly magnesium salts and / or calcium salts are preferably used.

  Alkali metal or alkaline earth metal sulfonate, alkali metal or alkaline earth metal phenate and alkali metal or alkaline earth metal salicylate include alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, alkyl Salicylic acid or the like is directly reacted with a metal base such as an oxide or hydroxide of an alkali metal or alkaline earth metal, or once converted to an alkali metal salt such as a sodium salt or potassium salt and then replaced with an alkaline earth metal salt In addition to the neutral salt (normal salt) obtained by, etc., these neutral salt (normal salt) and excess alkali metal or alkaline earth metal salt or alkali metal or alkaline earth metal base (alkali metal or Alkali earth metal hydroxides and acids Product) heated in the presence of water, or neutral salt (normal salt) of alkali metal or alkaline earth metal in the presence of carbon dioxide, boric acid or borate. An overbased salt (superbasic salt) obtained by reacting with a base such as a product is also included. These reactions are usually carried out in a solvent (an aliphatic hydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent such as xylene, a light lubricating base oil).

  In addition, metal detergents are usually marketed in a state diluted with a light lubricating base oil or the like, and are available, but generally the metal content is 1.0 to 20% by mass. It is desirable to use 2.0 to 16% by mass. The base number of the metal detergent is usually 0 to 500 mgKOH / g, preferably 20 to 450 mgKOH / g. The base number referred to here is 7. JIS K2501 “Petroleum products and lubricating oils-Neutralization number test method”. Means the base number measured by the perchloric acid method according to the above.

  In the present invention, one selected from sulfonates, phenates, salicylates and the like of alkali metals or alkaline earth metals can be used alone or in combination of two or more. As the metal detergent, alkali metal or alkaline earth metal salicylate is particularly preferred in that it has a large friction reducing effect and / or wear prevention effect due to low ashing and a long drain property. Moreover, it is especially preferable to use an alkali metal or alkaline earth metal sulfonate from the point which can suppress a viscosity increase more.

  The metal ratio of the metal-based detergent is not particularly limited, and usually 20 or less can be used. However, a metal having a metal ratio of 1 to 10 is preferable because it can further improve the friction reduction effect and the long drain property. It is preferable that it consists of 1 type (s) or 2 or more types chosen from a system detergent. The metal ratio here is represented by the valence of the metal element in the metal detergent × the metal element content (mol%) / the soap group content (mol%). The metal elements are calcium and magnesium. Etc., a soap group means a sulfonic acid group, a salicylic acid group, and the like.

  As the metal detergent, alkali metal or alkaline earth metal salicylate is particularly preferable in that it has a large friction reducing effect due to low ashing and is excellent in long drain properties.

  The upper limit of the content of the metallic detergent in the lubricating oil composition of the present invention is not particularly limited and is usually 0.5% by mass or less based on the total amount of the composition, but the composition based on the total amount of the composition It is preferable to adjust together with other additives so that the sulfated ash content of the product is 1.0% by mass or less. From such a viewpoint, the content of the metal detergent is preferably 0.3% by mass or less, more preferably 0.23% by mass or less, in terms of metal element, based on the total amount of the composition. Further, the content of the metal detergent is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and further preferably 0.15% by mass or more. When the content of the metal detergent is less than 0.01% by mass, it is difficult to obtain long drain performance such as high temperature cleanability, oxidation stability, and base number maintenance, which is not preferable.

  Moreover, 0.1-500 are preferable and, as for mass ratio (M / Mo) of the metal (M) contained in a metal type cleaning agent, and molybdenum (Mo) contained in an organic molybdenum compound, 2-100 are more preferable. 3 to 60 are more preferable, 5 to 50 are more preferable, and 10 to 40 are particularly preferable.

  The lubricating oil composition of the present invention preferably further contains an ashless dispersant.

  As the ashless dispersant, any ashless dispersant used in lubricating oils can be used. For example, at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms is included in the molecule. Examples thereof include nitrogen-containing compounds or derivatives thereof, or modified products of alkenyl succinimide. One type or two or more types arbitrarily selected from these can be blended.

  The alkyl group or alkenyl group has 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms. When the carbon number of the alkyl group or alkenyl group is less than 40, the solubility of the compound in the lubricating base oil decreases. On the other hand, when the carbon number of the alkyl group or alkenyl group exceeds 400, the low temperature of the lubricating oil composition Since fluidity | liquidity deteriorates, it is unpreferable respectively. This alkyl group or alkenyl group may be linear or branched, but specifically, preferred are derived from olefin oligomers such as propylene, 1-butene and isobutylene, and co-oligomers of ethylene and propylene. And a branched alkyl group and a branched alkenyl group.

Specific examples of the ashless dispersant include the following compounds. One or more compounds selected from these can be used.
(I) Succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof (II) At least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule A benzylamine having a derivative thereof (III) A polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof.

［式中、Ｒ^７は炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基を示し、ｍは１〜５、好ましくは２〜４の整数を示す。］

［式中、Ｒ^８及びＲ^９は、それぞれ個別に炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基、更に好ましくはポリブテニル基を示し、ｍは０〜４、好ましくは１〜３の整数を示す。］ More specifically, examples of the (I) succinimide include compounds represented by the following general formula (5) or (6).

[Wherein, R ⁷ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and m represents an integer of 1 to 5, preferably 2 to 4. ]

[Wherein R ⁸ and R ⁹ each independently represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, more preferably a polybutenyl group, and m is 0 to 4, preferably 1 to 1. An integer of 3 is shown. ]

  The succinimide is represented by the formula (5) in which succinic anhydride is added to one end of the polyamine, and the formula (6) in which a so-called monotype succinimide is added to both ends of the polyamine. The so-called bis-type succinimide represented by the formula (1) is included, but the lubricating oil composition of the present invention may contain only one of them or a mixture thereof.

  The method for producing the succinimide is not particularly limited. For example, an alkyl or alkenyl succinic acid obtained by reacting a compound having an alkyl group or alkenyl group having 40 to 400 carbon atoms with maleic anhydride at 100 to 200 ° C. is a polyamine. It can obtain by making it react. Specific examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

［式中、Ｒ^１０は、炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基を示し、ｐは１〜５、好ましくは２〜４の整数を示す。］ More specifically, examples of (II) benzylamine include compounds represented by the following general formula (7).

[Wherein, R ¹⁰ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and p represents an integer of 1 to 5, preferably 2 to 4. ]

  Although the manufacturing method of the said benzylamine is not limited at all, For example, after making polyolefin, such as a propylene oligomer, polybutene, and an ethylene-alpha-olefin copolymer, react with phenol to make alkylphenol, this is made into formaldehyde and It can be obtained by reacting polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine by Mannich reaction.

More specifically, examples of the (III) polyamine include compounds represented by the following general formula (8).
R ¹¹ —NH— (CH ₂ CH ₂ NH) _q —H (8)
[Wherein, R ¹¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and q represents an integer of 1 to 5, preferably 2 to 4. ]

  The method for producing the polyamine is not limited in any way. For example, after chlorinating a polyolefin such as propylene oligomer, polybutene, and ethylene-α-olefin copolymer, ammonia, ethylenediamine, diethylenetriamine, and triethylene are added thereto. It can be obtained by reacting polyamines such as tetramine, tetraethylenepentamine, and pentaethylenehexamine.

  Moreover, as a derivative of the nitrogen-containing compound mentioned as an example of the ashless dispersant, specifically, for example, the above-mentioned nitrogen-containing compound is a monocarboxylic acid having 1 to 30 carbon atoms (fatty acid, etc.), oxalic acid, phthalic acid, So-called acid modification in which a part or all of the remaining amino group and / or imino group is neutralized or amidated by the action of a polycarboxylic acid having 2 to 30 carbon atoms such as trimellitic acid or pyromellitic acid Compound: A so-called boron-modified compound obtained by allowing boric acid to act on the aforementioned nitrogen-containing compound to neutralize or amidate part or all of the remaining amino group and / or imino group; And a modified compound obtained by combining two or more kinds of modifications selected from acid modification, boron modification, and sulfur modification with the above-mentioned nitrogen-containing compound. Among these derivatives, boron-modified compounds of alkenyl succinimide are excellent in heat resistance and antioxidant properties, and are also effective in the lubricating oil composition of the present invention to further enhance base number maintenance and high temperature cleanability.

  When the ashless dispersant is contained in the lubricating oil composition of the present invention, the content is usually 0.01 to 20% by mass, preferably 0.1 to 10% by mass, based on the total amount of the lubricating oil composition. is there. When the content of the ashless dispersant is less than 0.01% by mass, the effect of maintaining the base number at high temperatures is small. On the other hand, when the content exceeds 20% by mass, the low-temperature fluidity of the lubricating oil composition is greatly increased. Since it deteriorates, it is not preferable respectively.

  Moreover, it is preferable that the lubricating oil composition of the present invention further contains a chain termination type antioxidant. Thereby, since the antioxidant property of a lubricating oil composition is improved more, the base number maintenance property and high temperature detergency in this invention can be improved more.

  Any chain-stopping antioxidant can be used as long as it is generally used in lubricating oils such as phenol-based antioxidants, amine-based antioxidants, and metal-based antioxidants.

  Examples of phenolic antioxidants include 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4 ′. -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl) 6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2, 6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6) -Tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4- Hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3-methyl-5-tert-butyl-4-hydroxyphenyl substituted fatty acid esters and the like are preferable examples. Can do. These may be used individually by 1 type, or may mix and use 2 or more types.

  Examples of amine-based antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine. These may be used individually by 1 type, or may mix and use 2 or more types.

  Further, the phenolic antioxidant and the amine antioxidant may be used in combination.

  When the chain-stopping antioxidant is contained in the lubricating oil composition of the present invention, the content is usually 5.0% by mass or less, preferably 3.0% by mass or less, based on the total amount of the lubricating oil composition. Yes, more preferably 2.5% by mass or less. When the content exceeds 5.0% by mass, it is not preferable because sufficient antioxidant properties corresponding to the content cannot be obtained. On the other hand, the content is preferably 0.1% by mass or more, preferably 1% by mass, based on the total amount of the lubricating oil composition, in order to further improve the base number maintenance property and high temperature cleanability in the process of lubricating oil deterioration. That's it.

  In addition, when the lubricating oil composition of the present invention contains a compound that does not dissolve in the lubricating base oil or an additive having low solubility (for example, zinc dialkyl phosphate that is solid at room temperature), lubrication of the additive Nitrogen-containing compounds (for example, amine compounds as ashless dispersants and amine-based antioxidants as chain-stopping antioxidants or the like from the viewpoint of improving solubility in oil base oils and shortening the production time of lubricating oil compositions) It is particularly preferable to mix a solution or reaction product obtained by mixing and dissolving or reacting with a phosphorus-based additive as an oil-soluble additive in a lubricating oil composition. As a production example of such an oil-soluble additive, for example, a phosphorus-based additive and the above nitrogen-containing compound are preferably 15 to 150 ° C., preferably 30 to 120 in an organic solvent such as hexane, toluene, decalin and the like. ℃, particularly preferably at 40 to 90 ° C. for 10 minutes to 5 hours, preferably 20 minutes to 3 hours, particularly preferably 30 minutes to 1 hour to dissolve or react, and the solvent is distilled off by distillation under reduced pressure or the like. can get.

In order to further improve the performance of the lubricating oil composition of the present invention, any additive commonly used in lubricating oils can be added depending on the purpose. Examples of such additives include wear inhibitors, friction modifiers, viscosity index improvers, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, antifoaming agents, and colorants. An agent etc. can be mentioned.
Antiwear agents include, for example, disulfides, sulfurized olefins, sulfurized fats and oils, dithiophosphoric acid metal salts (such as zinc salts and molybdenum salts), dithiocarbamic acid metal salts (such as zinc salts and molybdenum salts), dithiophosphoric acid esters and derivatives thereof (olefins). Reaction products with cyclopentadiene, (methyl) methacrylic acid, propionic acid, etc .; in the case of propionic acid, those added to the β-position are preferred.), Sulfur-containing compounds such as trithiophosphates and dithiocarbamates. These can usually be contained in the range of 0.005 to 5% by mass as long as the performance of the composition of the present invention is not significantly impaired, but from the viewpoint of low sulfur and long drain properties, the content thereof Is a sulfur conversion value, preferably 0.1% by mass or less, and more preferably 0.05% by mass or less.

  As the friction modifier, any compound usually used as a friction modifier for lubricating oils can be used. For example, molybdenum friction modifiers such as molybdenum disulfide, molybdenum dithiocarbamate, molybdenum dithiophosphate, carbon number 6 An amine compound, a fatty acid ester, a fatty acid amide, a fatty acid, a fatty alcohol, a fat having at least one alkyl group or alkenyl group of -30, in particular, a straight-chain alkyl group or straight-chain alkenyl group having 6 to 30 carbon atoms in the molecule. Ashless friction modifiers such as group ethers, hydrazides (eg oleyl hydrazide), semicarbazides, ureas, ureidos, biurets and the like. The content of these friction modifiers is usually 0.1 to 5% by mass.

  As the viscosity index improver, specifically, a so-called non-dispersed viscosity index improver such as a polymer or copolymer of one or more monomers selected from various methacrylates or a hydrogenated product thereof, Or a so-called dispersion-type viscosity index improver obtained by copolymerizing various methacrylic esters containing a nitrogen compound, a non-dispersion type or a dispersion type ethylene-α-olefin copolymer (propylene, 1-butene, 1 -Pentene, etc.) or a hydrogenated product thereof, polyisobutylene or a hydrogenated product thereof, a hydrogenated product of a styrene-diene copolymer, a styrene-maleic anhydride ester copolymer, and a polyalkylstyrene.

  The molecular weight of these viscosity index improvers needs to be selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is usually 5,000 to 1,000,000, preferably 100,000 to 900,000 in the case of dispersed and non-dispersed polymethacrylates, for example. In the case of polyisobutylene or a hydride thereof, usually 800 to 5,000, preferably 1,000 to 4,000, and in the case of an ethylene-α-olefin copolymer or a hydride thereof, usually 800 to 500. 3,000, preferably 3,000 to 200,000 are used.

  Further, among these viscosity index improvers, when an ethylene-α-olefin copolymer or a hydride thereof is used, a lubricating oil composition particularly excellent in shear stability can be obtained. One or two or more compounds arbitrarily selected from the above viscosity index improvers can be contained in any amount. The content of the viscosity index improver is usually 0.1 to 20% by mass based on the lubricating oil composition.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, and imidazole compounds.

  Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.

  Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

  Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.

  Examples of the antifoaming agent include silicone, fluorosilicone, and fluoroalkyl ether.

  When these additives are contained in the lubricating oil composition of the present invention, the content is based on the total amount of the lubricating oil composition, and 0.005 to 5% by mass for each of the corrosion inhibitor, rust inhibitor, and demulsifier. The metal deactivator is usually selected in the range of 0.005 to 1% by mass, and the antifoaming agent is usually selected in the range of 0.0005 to 1% by mass.

  The sulfur content in the lubricating oil composition of the present invention is preferably 0.3% by mass or less, more preferably 0.2% by mass or less, and still more preferably 0.1% by mass or less. By setting the sulfur content to the upper limit or less, a low sulfur lubricating oil composition having excellent long drain properties can be realized.

  Further, in order to enhance the long drain property of the lubricating oil composition of the present invention and to reduce the adverse effects on the exhaust gas aftertreatment device as much as possible, it is preferable that the sulfated ash content of the lubricating oil composition is 1.0 mass% or less. , 0.8% by mass or less, more preferably 0.6% by mass or less, and particularly preferably 0.5% by mass or less. Here, the sulfated ash is JIS K 2272 5. The value measured by the method specified in “Testing method for sulfated ash” is mainly attributable to the metal-containing additive.

  The lubricating oil composition of the present invention can exhibit excellent performance when used in an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst. Therefore, it can be preferably used as a lubricating oil for internal combustion engines such as motorcycles, automobiles, gasoline engines for power generation and marine use, diesel engines, gas engines and the like. The lubricating oil composition of the present invention has a sulfur content of 100 mass ppm or less, preferably 50 mass ppm or less, more preferably 20 mass ppm or less, particularly preferably 10 mass ppm or less, gasoline, light oil, kerosene, or sulfur. An internal combustion engine using a low sulfur fuel (for example, LPG, natural gas, dimethyl ether, alcohol-based fuel, GTL (gas-liquid) fuel (gasoline fraction, kerosene fraction, light oil fraction), etc.) having a content of 1 ppm by mass or less It can be particularly preferably used as a lubricant for use. In addition, other lubricants that require wear prevention performance and long drain performance, such as drive system lubricants such as automatic or manual transmissions, wet brakes, hydraulic fluids, turbine oils, compressor oils, bearing oils, refrigerator oils, etc. It can also be suitably used as a lubricating oil.

  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 1-6, Comparative Examples 1-3]
In Examples 1 to 6 and Comparative Examples 1 to 3, lubricating oil compositions having the compositions shown in Tables 1 and 2 were prepared using the lubricating base oil and additives shown below, respectively. Tables 1 and 2 also show the calcium and phosphorus concentrations (element-converted values based on the total amount of the lubricating oil composition) of the lubricating oil composition obtained in each example or comparative example.
(Lubricant base oil)
Base oil 1: hydrorefined mineral oil (kinematic viscosity at 100 ° C .: 4.7 mm ² / s, viscosity index: 120)
(Phosphorus-containing additive)
Phosphorus-containing additive 1: a zinc salt of a phosphorus compound in which R ⁴ and R ⁵ in the general formula (2) are 2-ethylhexyl groups, R ⁶ is a hydrogen atom, and n is 0 (phosphorus content: 9 0.1% by mass, zinc content: 9.5% by mass)
Phosphorus-containing additive 2: A zinc salt of a phosphorus compound in which R ⁴ and R ⁵ in the general formula (2) are butyl groups, R ⁶ is a hydrogen atom, and n is 1 (phosphorus content: 13.2) (Mass%, zinc content: 13.2 mass%)
Phosphorus-containing additive 3: R ⁴ and R ⁵ in the general formula (2) are 2-ethylhexyl groups, R ⁶ is a hydrogen atom, and n is 1, a molybdenum salt of a phosphorus compound (phosphorus content: 4 (Mass%, molybdenum content: 23 mass%)
Phosphorus-containing additive 4: A zinc salt of a phosphorus compound in which R ⁴ and R ⁵ in the general formula (2) are 2-ethylhexyl groups, R ⁶ is a hydrogen atom, and n is 1 (phosphorus content: 9 (Mass%, zinc content: 9 mass%)
Phosphorus-containing additive 5: zinc dialkyldithiophosphate (alkyl group = sec-butyl group / sec-hexyl group, phosphorus content: 7.2 mass%, sulfur content: 15.2 mass%, zinc content: 7. 8% by mass)
Phosphorus-containing additive 6: zinc dialkyldithiophosphate (alkyl group = iso-propyl group / sec-hexyl group, phosphorus content: 7.2 mass%, sulfur content: 15.2 mass%, zinc content: 7. 8% by mass)
(Metal-based detergent)
Metal detergent 1: calcium salicylate (base number: 170 mgKOH / g, calcium content: 6% by mass)
Metal detergent 2: Calcium sulfonate (base number: 300 mgKOH / g, calcium content: 12.7% by mass)
(Ashless dispersant)
Ashless dispersant 1: polybutenyl succinimide (weight average molecular weight: 3000, nitrogen content: 1.3% by mass).
(Antioxidant)
Antioxidant 1: 4,4'-methylenebis-2,6-di-tert-butylphenol Antioxidant 2: Octyl diphenylamine (other additives)
Additive package 1: Mixture of polymethacrylate viscosity index improver, antifoaming agent and the like.

[Performance evaluation test 1: JASO high temperature oxidation test]
The performance evaluation test of the lubricating oil compositions of Examples 1 to 4 and Comparative Example 1 was performed in accordance with JASO (Japan Automobile Standard Organization) high temperature oxidation stability test (JASO M333-93) which is a bench top actual machine engine. The engine used was an in-line 6-cylinder engine with a displacement of 2.0 dm ³ and a DOHC type. The operating conditions were an oil temperature of 149 ° C., a rotation speed of 4800 rpm and a full load, and the test time was 96 hours. Then, a fuel having a sulfur content of 0.04% by mass was used in consideration of future exhaust gas regulations. In this test, the concentrations of calcium and phosphorus in the test oil at the time of 32 hours, 64 hours and 96 hours from the start of the test (0 hour) were measured, and the phosphorus / calcium ratio (molar ratio) was determined. The obtained results are shown in Table 3.

  From the results shown in Table 3, in the case of the lubricating oil composition of Comparative Example 1, the phosphorus / calcium ratio was smaller than the initial value during the process of decomposition of the phosphorus-based additive 5 (zinc dialkyldithiophosphate). It can be seen that the phosphorus in the oil has evaporated. On the other hand, in the case of the lubricating oil compositions of Examples 1 to 4, it was confirmed that no substantial decrease in the phosphorus / calcium ratio with the passage of operating time was observed, and phosphorus evaporation was sufficiently suppressed. It was.

[Performance evaluation test 2: Seq. IIIG test]
The performance evaluation tests of the lubricating oil compositions of Examples 5 and 6 and Comparative Examples 2 and 3 were conducted according to the ASTM D7320 high-temperature oxidation stability test which is a bench-top actual machine engine. The engine used was an in-line 6-cylinder engine with a displacement of 3.8 dm ³ and an OHV type. The operating conditions were an oil temperature of 150 ° C., a rotation speed of 3600 rpm, a full load, and a test time of 100 hours. Then, a fuel having a sulfur content of 0.04% by mass was used in consideration of future exhaust gas regulations. In this test, the concentration of calcium and phosphorus in the test oil after 20 hours, 40 hours, 60 hours, and 80 hours from the start of the test (0 hour) was measured to determine the phosphorus / calcium ratio (molar ratio). . Moreover, the average value of the abrasion amount of a cam and a lifter was calculated | required. Table 4 shows the obtained results.

  From the results shown in Table 4, in the case of the lubricating oil compositions of Comparative Examples 2 and 3, the phosphorus / calcium ratio from the initial value in the process of decomposition of the phosphorus-based additives 5 and 6 (both zinc dialkyldithiophosphates). It can be seen that the phosphorus in the test oil has evaporated. On the other hand, in the case of the lubricating oil compositions of Examples 5 and 6, no substantial decrease in the phosphorus / calcium ratio was observed with the passage of operating time, and it was confirmed that the evaporation of phosphorus was sufficiently suppressed. It was. In addition, the lubricating oil compositions of Examples 5 and 6 exhibited sufficient wear resistance.

Claims (2)

A lubricating base oil, a metal salt of a phosphorus compound represented by the following general formula (1), and a metal salt of at least one phosphorus compound selected from a metal salt of a phosphorus compound represented by the following general formula (2): Containing,
The content of the metal salt of the phosphorus compound is 0.005 to 0.5 mass% in terms of phosphorus element, based on the total amount of the lubricating oil composition,
A lubricating oil composition used for an internal combustion engine equipped with an oxidation catalyst or a three-way catalyst.

[In General Formula (1), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ² and R ³ may be the same or different. And each represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a group containing at least one selected from sulfur, oxygen, and nitrogen, and m represents 0 or 1. ]

[In General Formula (2), R ⁴ represents a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and R ⁵ and R ⁶ may be the same or different. It may be a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms or a group containing at least one selected from sulfur, oxygen and nitrogen, and n represents 0 or 1. ]   The lubricating oil composition according to claim 1, wherein a phosphorus concentration in the lubricating oil composition is 0.01 to 0.10% by mass based on the total amount of the lubricating oil composition.