CN108699484A - Lubricating oil composition - Google Patents

Abstract

The lubricating oil composition of the present invention comprises, in addition to a base oil: an olefin oligomer (A) having a mass-average molecular weight of 500 to 5000 inclusive, an antioxidant (B) comprising a phenol antioxidant (B-1) and an amine antioxidant (B-2), and an alkaline earth metal detergent (C), wherein the alkaline earth metal detergent (C) is contained in an amount of 1700 to 2700 mass ppm in terms of alkaline earth metal atoms, based on the total amount of the lubricating oil composition, and has a kinematic viscosity of 4.0mm at 100 DEG C²6.0mm of a length of more than s²The ratio of the water to the water is less than s.

Description

lubricating oil composition

technical field

This invention relates to lubricating oil compositions.

Background technique

The present invention relates to a lubricating oil composition, and relates to a lubricating oil composition suitable for use in transmissions, for example.

In recent years, from the standpoint of reducing carbon dioxide gas emissions and reducing consumption of fossil fuels, fuel economy of automobiles has been strongly demanded. For example, even in lubricating oils for automotive gears, low viscosity is being promoted in order to reduce stirring resistance. However, lowering of the viscosity of lubricating oil lowers the strength of the oil film in the high-temperature region, and there is a concern that the seizure resistance, wear resistance, fatigue resistance, and the like may be lowered. On the other hand, it is effective to maintain the viscosity of the lubricating oil high in the high-temperature range and to lower the viscosity of the lubricating oil in the usual temperature range. That is, it is effective to increase the viscosity index.

However, in order to increase the viscosity index, it is necessary to add a viscosity index improver such as a polymer to the lubricating oil. These polymers are subjected to shear in use, thereby causing a decrease in the viscosity of the lubricating oil. Therefore, when a viscosity index improver is blended into a lubricating oil, it is necessary to take into account the above-mentioned decrease in viscosity when the actual vehicle is running.

In addition, downsizing and weight reduction have been promoted in the design of the transmission. Due to the reduction in size and weight of the transmission, the mechanical load on the lubricating part increases, so the lubricating oil filled is required to further improve the lubricity. In addition, the heat load is also increased, and therefore, further improvements in the heat resistance and oxidation stability of lubricating oils are required.

If the heat resistance and oxidation stability of the lubricating oil deteriorate, sludge is generated, which adheres to lubricated parts, resulting in poor lubrication. For example, operational failures of bearings and the like due to sludge adhesion can be mentioned. In addition, especially in manual transmissions, the adhesion of sludge in the synchromesh mechanism that performs the shifting function causes a decrease in shifting feeling due to a decrease in friction characteristics, and further causes a decrease in gear shifting due to the solidification of the synchronizer ring. Motion failure.

In Patent Documents 1 and 2, the low-viscosity base oil was blended with a viscosity index improver with excellent shear stability to further reduce the viscosity of lubricating oil (kinematic viscosity at 100°C: at least 6.2 mm ² /s) . However, since the decrease in the viscosity of the lubricating oil due to the actual running of the vehicle cannot be completely suppressed, there is a limit in reducing the viscosity of the new oil.

In Patent Document 3, without adding a polymethacrylate-based compound to the lubricating oil, low viscosity was achieved (kinematic viscosity at 100°C: about 6.0 mm ² /s or more in Examples) At the same time, by adding a molybdenum compound to the lubricating oil, wear in the synchromesh is prevented and the friction characteristics are maintained.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2012-193255

Patent Document 2: Japanese Patent Laid-Open No. 2014-177605

Patent Document 3: Japanese Patent Laid-Open No. 2014-98090.

Contents of the invention

The problem to be solved by the invention

The techniques described in Patent Documents 1 to 3 do not solve the concern of lowering the viscosity of lubricating oil. In addition, the demands for improvement in heat resistance and oxidation stability accompanying downsizing and weight reduction of devices have not been sufficiently satisfied.

The present invention is made in view of the above circumstances. That is, an object of the present invention is to provide a lubricating oil composition that achieves low viscosity, suppresses a decrease in viscosity when an actual vehicle is running, and improves heat resistance and oxidation stability.

means to solve the problem

As a result of intensive studies, the inventors of the present invention have found that a lubricating oil composition containing specific components (A) to (C) as essential components in addition to a base oil can solve the above-mentioned problems.

That is, the present invention provides the following [1] to [5].

[1] A lubricating oil composition comprising, in addition to a base oil:

An olefin oligomer (A) having a mass average molecular weight of 500 to 5000,

An antioxidant (B) comprising a phenolic antioxidant (B-1) and an amine antioxidant (B-2), and

Alkaline earth metal-based detergent (C),

The content of the alkaline earth metal-based detergent (C) in terms of alkaline earth metal atoms is 1700 mass ppm or more and 2700 mass ppm or less based on the total amount of the lubricating oil composition,

The kinematic viscosity at 100° C. is not less than 4.0 mm ² /s and not more than 6.0 mm ² /s.

[2] A transmission filled with the lubricating oil composition described in [1] above.

[3] A lubricating method using the lubricating oil composition described in [1] above.

[4] A method of using the lubricating oil composition described in the above [1] in a transmission.

[5] A method for producing a lubricating oil composition, comprising separately blending into a base oil: an olefin oligomer (A) having a mass average molecular weight of 500 to 5,000, a phenolic antioxidant (B-1) and an amine antioxidant The antioxidant (B) of the oxidizing agent (B-2), and the alkaline earth metal-based detergent (C), and the alkaline-earth metal-based detergent (C) is blended so that the alkaline earth metal atom is The converted content is not less than 1700 mass ppm and not more than 2700 mass ppm.

The effect of the invention

According to the present invention, it is possible to provide a lubricating oil composition that achieves low viscosity, suppresses a decrease in viscosity when an actual vehicle is running, and improves heat resistance and oxidation stability.

Detailed ways

Hereinafter, an embodiment of the present invention will be described in detail. In the present invention, the "kinematic viscosity at 100°C" and "kinematic viscosity at 40°C" of a base oil or lubricating oil composition refer to values measured based on the method described in JIS K 2283:2000.

In the present invention, the content of alkaline earth metal atoms in the lubricating oil composition refers to a value measured in accordance with JPI-5S-38-92.

In the present invention, "alkaline earth metal atom" refers to a beryllium atom, a magnesium atom, a calcium atom, a strontium atom, and a barium atom.

The lubricating oil composition according to this embodiment contains, in addition to a base oil, an olefin oligomer (A) having a mass average molecular weight of 500 to 5,000, a phenolic antioxidant (B-1) and an amine antioxidant. The antioxidant (B) of the antioxidant (B-2) and the alkaline earth metal-based detergent (C), the content of the alkaline-earth metal-based detergent (C) in terms of alkaline earth metal atoms is based on the total amount of the lubricating oil composition. The basis is 1700 mass ppm to 2700 mass ppm, and the kinematic viscosity at 100° C. is 4.0 mm ² /s to 6.0 mm ² /s.

In the lubricating oil composition of one aspect of the present invention, the total content of the base oil, olefin oligomer (A), antioxidant (B), and alkaline earth metal-based detergent (C) is calculated as the total amount of the lubricating oil composition Based on (100% by mass), preferably 70% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, Moreover, it is normally 100 mass % or less, Preferably it is 99.9 mass % or less, More preferably, it is 99 mass % or less.

Hereinafter, each component mixed with the lubricating oil composition of this embodiment is demonstrated.

＜Olefin Oligomer (A)＞

The lubricating oil composition of this embodiment contains an olefin oligomer (A), and the mass average molecular weight of this olefin oligomer (A) must be 500-5000.

The olefin oligomer (A) has fluidity in a high-temperature part of a device, such as a transmission, and has an effect of washing away generated sludge. If the molecular weight of an olefin oligomer (A) is less than 500, it will evaporate in a high-temperature range, and a sufficient washing|cleaning effect will not be exhibited. When the molecular weight of an olefin oligomer (A) exceeds 5000, the fluidity|fluidity in a high temperature range cannot be ensured, and the effect of washing|cleaning sludge cannot fully be exhibited.

The mass average molecular weight of the olefin oligomer (A) is preferably from 600 to 4500, more preferably from 700 to 4000, still more preferably from 800 to 3000.

The olefin oligomer (A) has a polyolefin skeleton and is not particularly limited as long as the molecular weight is 500 or more and 5000 or less. The olefin oligomer (A) preferably has a structural unit derived from an unsaturated hydrocarbon monomer having 2 to 5 carbon atoms, examples of which include propylene oligomers, isobutylene oligomers, polybutene, and polyisobutylene , octene oligomers, decene oligomers, and ethylene-propylene oligomers and other olefin oligomers. Among them, polybutene-1 is suitably used.

The olefin oligomer (A) may be used alone or in combination of two or more.

The olefin oligomer (A) can be blended within a range in which the kinematic viscosity at 100° C. of the lubricating oil composition of the present embodiment is 4.0 mm ² /s or more and 6.0 mm ² /s or less. Specifically, the content of the olefin oligomer (A) having a mass average molecular weight of 500 to 5000 in the lubricating oil composition of the present embodiment is preferably 0.8% by mass based on the total amount of the lubricating oil composition. It is more than or equal to 4.5 mass %, More preferably, it is 1 mass % or more and 4 mass % or less, More preferably, it is 1.2 mass % or more and 2.5 mass % or less.

＜Antioxidant (B)＞

The lubricating oil composition of this embodiment contains an antioxidant (B) containing a phenolic antioxidant (B-1) and an amine antioxidant (B-2). In the present embodiment, as the antioxidant (B), it is necessary to combine the phenolic antioxidant (B-1) and the amine antioxidant (B-2), and sufficient antioxidant performance cannot be obtained when only one is used.

The phenolic antioxidant (B-1) is not particularly limited as long as it has a phenolic structure and has an effect of inhibiting oxidation of a lubricating oil composition.

Examples of phenolic antioxidants (B-1) include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4,6 -Tri-tert-butylphenol, 2,6-di-tert-butyl-4-hydroxymethylphenol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2, 6-di-tert-butyl-4-(N,N'-dimethylaminomethyl)phenol, 2,6-di-tert-amyl-4-methylphenol, 2,6-di-tert-amyl-p-methylphenol Phenol, 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'-butylene bis(3-methyl-6-tert-butylphenol), 4,4'-isopropylidene bis(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), 2,4-dimethyl-6-tert-butylphenol, 4,4'-thiobis(2-methyl-6-tert-butyl phenylphenol), 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], 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate deca Trialkyl esters, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propane Octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl propionate, and 3-(3-methyl-5-tert-butyl-4-hydroxyphenyl) Octyl propionate etc.

In addition, in this embodiment, phenolic antioxidant (B-1) may be used individually by 1 type, and may use it in combination of 2 or more types.

The amine antioxidant (B-2) which can be used in this embodiment is not specifically limited. For example, the compound represented by the following general formula (B-2-1) is mentioned.

[chemical 1]

(In the ^formula , Ar and Ar each independently represent ^a carbon atom selected from phenyl, phenyl substituted by alkyl, phenyl substituted by aralkyl, naphthyl, and naphthyl substituted by alkyl The aryl group whose number is 6~24).

The amine antioxidant (B-2) is more specifically, preferably selected from phenyl-α-naphthylamines represented by the following general formula (B-2-2), and general formula (B-2-3 ) shown in the diphenylamines.

[Chem 2]

(In the formula, R ¹ represents a hydrogen atom or an alkyl group with 1 to 18 carbon atoms).

[Chem 3]

(In the ^formula , R2 and ^R3 each independently represent a hydrogen atom, an alkyl group with 1 to 18 carbon atoms, or an aralkyl group with 7 to 18 carbon atoms).

Examples of specific amine antioxidants (B-2) include monoalkyldiphenylamines such as monooctyldiphenylamine and monononyldiphenylamine; 4,4'-dibutyl Diphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyl dialkyldiphenylamine, 4,4'-dinonyldiphenylamine and other dialkyldiphenylamine series; tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine , tetranonyldiphenylamine and other polyalkylene diphenylamine series, α-naphthylamine, phenyl-α-naphthylamine and other naphthylamine series, butylphenyl-α-naphthylamine, pentylamine phenylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine, nonylphenyl-α-naphthylamine Alkyl substituted phenyl-α-naphthylamine such as phenylamine; diphenylamine, monobutylphenylmonoctylphenylamine, N-p-tert-octylphenyl-1-naphthylamine, 4,4 '-bis(α,α-dimethylbenzyl)diphenylamine, etc.

In addition, in this embodiment, the amine antioxidant (B-2) may be used individually by 1 type, and may use it in combination of 2 or more types.

Specific examples of the phenolic antioxidant (B-1) and the amine antioxidant (B-2) that can be used in combination as the antioxidant (B) include pentaerythritol tetrakis[3-(3,5- Di-tert-butyl-4-hydroxyphenyl) propionate] or (B-1) of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, and as Any combination of (B-2) of monobutylphenylmonooctylphenylamine or N-p-tert-octylphenyl-1-naphthylamine.

In the present embodiment, the content of the antioxidant (B) including the phenolic antioxidant (B-1) and the amine antioxidant (B-2) is preferably 0.5% by mass or more based on the total amount of the lubricating oil composition And 3.0 mass % or less, more preferably 0.5 mass % or more and 2.0 mass % or less, still more preferably 1 mass % or more and 2 mass % or less. Here, content of antioxidant (B) shows the total amount of phenolic antioxidant (B-1) and amine antioxidant (B-2).

If the content of the antioxidant (B) is 0.5% by mass or more, the antioxidant effect can be sufficiently exhibited. From the viewpoint of the antioxidant effect, it is sufficient that the upper limit of the content of the antioxidant (B) is 3.0% by mass.

In addition, the mass ratio [(B-2)/(B-1)] of the phenolic antioxidant (B-1) to the amine antioxidant (B-2) is not particularly limited, but is preferably 1/3 to 3/ About 1, more preferably about 1/2 to 2/1.

Furthermore, in this embodiment, the total content of the phenolic antioxidant (B-1) and the amine antioxidant (B-2) in the antioxidant (B) is preferably based on the total amount of the antioxidant (B). 60 mass % or more and 100 mass % or less, more preferably 70 mass % or more and 100 mass % or less, still more preferably 80 mass % or more and 100 mass % or less, still more preferably 90 mass % or more and 100 mass % or less, Still more preferably, it is 99% by mass or more and 100% by mass or less.

As described above, in the present embodiment, it is necessary to use the phenolic antioxidant (B-1) and the amine antioxidant (B-2) in combination as the antioxidant (B), but within the range that does not inhibit the effect of the present embodiment The inclusion of other antioxidants is not excluded. Examples of other antioxidants include molybdenum amine complex antioxidants.

As the molybdenum amine complex-based antioxidant, one obtained by reacting a hexavalent molybdenum compound, specifically, molybdenum trioxide and/or molybdic acid with an amine compound can be used, for example, according to JP 2003-252887 A The compound obtained by the production method described in .

＜Alkaline-earth metal-based detergent (C)＞

The lubricating oil composition of the present embodiment contains an alkaline earth metal-based detergent (C), and the content of the alkaline-earth metal-based detergent (C) in terms of alkaline earth metal atoms needs to be 1700% based on the total amount of the lubricating oil composition. Mass ppm or more and 2700 mass ppm or less.

The alkaline-earth metal-based detergent (C) suppresses the generation of sludge by the acid neutralization action of the degraded components generated in the oil, and also has a cleaning effect of dispersing the generated sludge.

If the content of the alkaline earth metal-based detergent (C) based on the total amount of the lubricating oil composition in terms of alkaline earth metal atoms is less than 1700 ppm by mass, the above-mentioned neutralization effect cannot be fully exhibited, and oxidation stability and resistance Poor heat. When the content of the alkaline earth metal-based detergent (C) exceeds 2700 mass ppm in terms of alkaline earth metal atoms, the amount of metal in the composition increases to form nuclei for sludge generation, resulting in poor heat resistance. The content of the alkaline earth metal-based detergent (C) in terms of alkaline earth metal atoms based on the total amount of the lubricating oil composition is preferably 1800 mass ppm to 2600 mass ppm, more preferably 1900 mass ppm to 2500 mass ppm Not more than, more preferably 2000 mass ppm or more and 2500 mass ppm or less.

As the alkaline-earth metal-based detergent (C), at least one selected from alkaline-earth metal sulfonates, alkaline-earth metal phenates, and alkaline-earth metal salicylates described in detail below may be used, or a mixture of two or more thereof may be used. . Among them, alkaline earth metal sulfonates are preferable in terms of heat resistance.

Examples of alkaline earth metal sulfonates include alkaline earth metal salts, especially magnesium salts, of alkylaromatic sulfonic acids obtained by sulfonating alkylaromatic compounds having a molecular weight of 300 to 1,500, preferably 400 to 700. and/or calcium salts, etc. Among them, calcium salts are preferably used. Examples of alkaline earth metal phenates include alkaline earth metal salts of alkylphenols, alkylphenol sulfides, and Mannich reactants of alkylphenols, especially magnesium salts and/or calcium salts, among which calcium salts are particularly preferred. Examples of alkaline earth metal salicylates include alkaline earth metal salts of alkylsalicylic acids, particularly magnesium salts and/or calcium salts, among which calcium salts are preferred.

The number of carbon atoms of the alkyl group constituting the alkaline earth metal-based detergent (C) is preferably 4 to 30, more preferably 6 to 18, and the alkyl group may be linear or branched. In addition, the above-mentioned alkyl group may be any of a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group.

In addition, the alkaline earth metal sulfonate, alkaline earth metal phenate, and alkaline earth metal salicylate may be any of neutral, basic, and overbased. As the neutral alkaline earth metal salt, for example, the Mannich reactant of the aforementioned alkyl aromatic sulfonic acid, alkyl phenol, alkyl phenol sulfide, alkyl phenol, alkyl salicylic acid, etc. Alkaline earth metal alkali reaction such as oxides and hydroxides of alkaline earth metals of calcium, or neutral alkaline earth metal sulfonates obtained by temporarily making alkali metal salts such as sodium salts and potassium salts and replacing them with alkaline earth metal salts, etc. neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates. As the basic alkaline earth metal salt, for example, by mixing the above-mentioned neutral alkaline earth metal sulfonate, neutral alkaline earth metal phenate and neutral alkaline earth metal salicylate with excess alkaline earth metal salt and alkaline earth metal alkali in water, Basic alkaline earth metal sulfonates, basic alkaline earth metal phenates and basic alkaline earth metal salicylates obtained by heating in the presence. As the overbased alkaline earth metal salt, for example, by making the above-mentioned neutral alkaline earth metal sulfonate, neutral alkaline earth metal phenate and neutral alkaline earth metal salicylate and alkaline earth metal carbonic acid in the presence of carbonic acid gas Overbased alkaline earth metal sulfonates, overbased alkaline earth metal phenates and overbased alkaline earth metal salicylates obtained by reacting salts or borates. Alkaline-earth metal-based detergents (C) are usually commercially available in a state diluted with light lubricating base oils, etc., and are generally available, and are generally preferably used with a metal content of 1.0 to 20% by mass, preferably 2.0 to 16% by mass. % of substances.

The metal ratio of the alkaline earth metal-based detergent (C) of the present embodiment is not particularly limited, and generally one kind or two or more kinds of metal ratios having a metal ratio of 20 or less can be used. The above-mentioned metal ratio is preferably 3 or less, more preferably 1.5 or less, particularly preferably 1.2 or less, and is preferable because it is excellent in oxidation stability, base number maintenance, and heat resistance at high temperatures.

It should be noted that the metal ratio referred to here is represented by the valence of the metal element in the metal-based detergent × metal element content (mol%)/soap base content (mol%), and the metal element refers to calcium, magnesium, etc., Soap group refers to sulfonic acid group, phenol group and salicylic acid group, etc.

The alkaline earth metal-based detergent (C) may be any of the above-mentioned neutral, basic, and overbased, and examples thereof include, for example, a detergent having a concentration of usually 10 mgKOH/g to 500 mgKOH/g, preferably 15 mgKOH/g to 450 mgKOH. Alkaline-earth metal-based detergents (C) having a base value of 1/g or less may be used alone or in combination of two or more. In the present embodiment, it is more preferably basic or overbasic, and preferably has a base value of not less than 150 mgKOH/g and not more than 450 mgKOH/g. By having a base value of not less than 150 mgKOH/g and not more than 450 mgKOH/g, it exhibits more excellent oxidation stability and is also excellent in heat resistance. In addition, the alkali value of the alkaline earth metal type detergent (C) referred to in this specification means the value measured by JISK2501:2003: Perchloric acid method. The alkali value of the alkaline earth metal-based detergent (C) is more preferably 200 mgKOH/g to 450 mgKOH/g, still more preferably 250 mgKOH/g to 400 mgKOH/g.

As the alkaline earth metal atoms contained in the alkaline earth metal detergent (C), one or more kinds selected from beryllium atoms, magnesium atoms, calcium atoms, strontium atoms, and barium atoms can be mentioned. From the viewpoint of properties, it is preferably calcium, magnesium, or barium, more preferably calcium or magnesium, and even more preferably calcium. As the alkaline earth metal-based detergent (C), calcium sulfonate is suitably used.

<Polymer (D) with a mass average molecular weight of more than 5,000>

The lubricating oil composition in this embodiment may contain a polymer (D) having a mass average molecular weight greater than 5,000. However, when the polymer (D) is contained, the content of the polymer (D) is preferably less than 50 parts by mass relative to 100 parts by mass of the olefin oligomer (A). If the ratio with respect to 100 mass parts of olefin oligomers (A) is the said range, heat resistance at the high temperature part of a transmission can be ensured, for example. In addition, as long as the amount of the polymer (D) is within the above range, the decrease in viscosity during the actual running of the vehicle due to shearing of the polymer compound or the like can be reduced without limitation. The content of the polymer (D) is more preferably less than 30 parts by mass, still more preferably less than 20 parts by mass relative to 100 parts by mass of the olefin oligomer (A). The mass average molecular weight of the polymer (D) is preferably 120,000 or less, more preferably 50,000 or less, still more preferably 40,000 or less.

The polymer (D) is not particularly limited, and examples thereof include polymethacrylate generally used as a pour point depressant. Since the lubricating oil composition according to the present embodiment can maintain stable oil film strength at high temperature even if it does not contain a viscosity index improver, it does not need to contain a viscosity index improver. Furthermore, even in the case of containing the polymer (D) classified as a viscosity index improver, excellent shear stability is achieved by setting it within the range of the above mass ratio.

＜Zinc dithiophosphate (E)＞

The lubricating oil composition in this embodiment may contain zinc dithiophosphate (E). As zinc dithiophosphate (E), what is represented by the following general formula (E-1) is used.

[chemical 4]

(In the formula, R ⁴ to R ⁷ each independently represent a straight chain, branched or cyclic alkyl group with 1 to 24 carbon atoms, and a straight chain with 1 to 24 carbon atoms, branched or cyclic alkenyl groups).

In the general formula (E-1), R ⁴ to R ⁷ each independently represent a linear, branched, or cyclic alkyl group with 1 to 24 carbon atoms, or a straight chain with 1 to 24 carbon atoms. The chain-like, branched-chain, and cyclic alkenyl groups may be different or the same, but are preferably the same from the viewpoint of ease of production.

R ⁴ to R ⁷ are preferably linear, and R ⁴ to R ⁷ are preferably alkyl.

Examples of the alkyl group in R ⁴ to R ⁷ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, Alkyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, hexadecyl, di Dodecyl, Tricosyl and Tetracosyl can be straight chain, branched or cyclic. In addition, examples of the alkenyl group include vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, deca Didecenyl, Tridecenyl, Tetradecenyl, Pentadecenyl, Hexadecenyl, Heptadecenyl, Octadecenyl, Nonadecenyl, Eicosyl Alkenyl, uncocenyl, dococenyl, tritricenyl, and tetradecenyl, which may be straight-chain, branched, or cyclic, and double The positions of the keys are also arbitrary.

When the lubricating oil composition of the present embodiment contains zinc dithiophosphate (E), its content is usually 0.05% by mass to 5% by mass, preferably 0.1% by mass to 3% by mass based on the total amount of the composition. % or less, more preferably 1 mass % or more and 2.5 mass % or less. When the content of zinc dithiophosphate (E) is within the above range, for example, when used as MTF (manual transmission fluid), the coefficient of friction (μ) can be increased during gear shifting, and shift feeling can be improved.

＜Base oil＞

The base oil used in this embodiment may be either mineral oil or synthetic oil, or a mixed oil of mineral oil and synthetic oil may be used.

Mineral oils include, for example, atmospheric residue obtained by atmospheric distillation of crude oil such as paraffinic crude oil, mixed crude oil, and naphthene crude oil; Oil; refined oils and waxes obtained by subjecting the distillate oil to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrogenation modification.

In the present embodiment, from the viewpoint of suppressing sludge formation, mineral oils classified as Type 2 or Type 3 in the base oil category of API (American Petroleum Institute) are preferable. Moreover, in order to make oxidation stability more favorable, it is more preferable to be classified into 3 types. It should be noted that the base oils classified as Class 2 have a saturated content of 90% or more, a sulfur content of 0.03% or less, and a viscosity index of less than 80 to 120. Base oils classified as Class 3 have a saturated content of 90% or more, a sulfur content of 0.03% or less, and a viscosity index of 120 or more.

The sulfur content is a value measured in accordance with JIS K2541-6:2013, and the saturated content is a value measured in accordance with ASTM D 2007. Furthermore, the viscosity index is a value measured according to JISK 2283:2000.

Examples of synthetic oils include polyhydric alcohol esters, dibasic acid esters (such as bis(tridecyl) glutarate, etc.), tribasic acid esters (such as 2-ethylhexyl trimellitate), phosphoric acid esters, etc. Various esters such as esters; various ethers such as polyphenylene ethers; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes; ) wax) synthetic oil obtained by isomerization, etc.

In the present embodiment, these base oils may be used alone or in combination of two or more. The kinematic viscosity at 100°C of the base oil used in the present embodiment is preferably 2.0 mm ² /s to 30 mm ² /s, more preferably 2.5 mm ² /s to 25 mm ² /s, still more preferably 3.0 mm ² /s or more and 20 mm ² /s or less.

The viscosity index of the base oil used in this embodiment is preferably 80 or more, more preferably 90 or more, more preferably 120 or more.

In addition, when using the mixed oil obtained by combining 2 or more types of base oils, it is preferable that the kinematic viscosity and viscosity index of this mixed oil are in the said range.

In addition, in the present embodiment, the content of the base oil is preferably 75% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, and more preferably 97% by mass based on the total amount of the composition. or less, more preferably 95% by mass or less.

＜Other additives＞

The lubricating oil composition for a transmission according to the present embodiment may contain additives such as a friction modifier, a dispersant, and an antifoaming agent. However, the pour point depressant is classified as a polymer (D) with a mass average molecular weight greater than 5,000, and is not included in other additives.

The compounding amount of the additive is preferably 10% by mass or less, more preferably 7.5% by mass or less, and still more preferably 5.0% by mass or less, based on the total amount of the composition.

<Physical properties of lubricating oil composition>

The kinematic viscosity at 100° C. of the lubricating oil composition of the present embodiment is not less than 4.0 mm ² /s and not more than 6.0 mm ² /s. If the kinematic viscosity at 100° C. is lower than 4.0 mm ² /s, the oil film strength decreases, resulting in decreased seizure resistance, wear resistance, fatigue resistance, and the like. If the kinematic viscosity at 100° C. exceeds 6.0 mm ² /s, the stirring resistance will increase, which is not preferable in terms of fuel efficiency.

The kinematic viscosity at 100° C. of the lubricating oil composition according to the present embodiment is more preferably 4.5 mm ² /s to 5.8 mm ² /s, still more preferably 4.6 mm ² /s to 5.5 mm ² /s.

＜Applications, lubrication methods, transmissions＞

The lubricating oil composition of the present embodiment can be suitably used for transmission oil applications.

The lubricating oil composition of the present embodiment has a low viscosity, suppresses a decrease in viscosity when an actual vehicle is running, and is excellent in heat resistance and oxidation stability. Therefore, in a small and lightweight transmission, for example, the adhesion of sludge in the synchromesh mechanism is suppressed, and a good shift feeling is obtained. In addition, the synchronizer ring action can be kept good. Therefore, this embodiment can also provide a lubrication method and a usage method using the above-mentioned lubricating oil composition.

In addition, the present embodiment can also provide a transmission filled with the lubricating oil composition described above.

<Manufacturing method of lubricating oil composition>

The lubricating oil composition of this embodiment can be produced by the following method of producing a lubricating oil composition: separately blending: an olefin oligomer (A) having a mass average molecular weight of 500 to 5000; Antioxidant (B) of oxidant (B-1) and amine antioxidant (B-2), and alkaline earth metal detergent (C), mix alkaline earth metal detergent (C) so that the aforementioned lubricating oil composition Based on the total amount of alkaline earth metal atoms, the content is not less than 1700 mass ppm and not more than 2700 mass ppm.

Example

Next, the present embodiment will be described more specifically by way of examples, but the present embodiment is not limited by these examples.

<Each measurement method>

(1) Mass average molecular weight (Mw)

It measures by standard polystyrene conversion by the GPC (gel permeation chromatography) method. Specifically, it measured on the following apparatus and conditions.

・GPC device: Waters 1515 Isocratic HPLC Pump + Waters 2414 Refractive IndexDetector (both made by Waters)

・Column: Connect two "TSKgel SuperMultiporeHZ-M" (manufactured by Tosoh Corporation)

・Column temperature: 40°C

・Eluent: Tetrahydrofuran

・Flow rate: 0.35mL/min

・Detector: Refractive index detector.

(2) Kinematic viscosity

According to JIS K2283:2000, the kinematic viscosity at each temperature was measured.

(3) Calcium atom content, nitrogen atom content, phosphorus atom content and sulfur atom content in the lubricating oil composition

The content of each of the above components was measured by the following method.

(3-1) Calcium atom (Ca) content and phosphorus atom (P) content

Measured according to JPI-5S-38-92.

(3-2) Nitrogen atom (N) content

Measured in accordance with JIS K2609:1998.

(3-3) Content of sulfur atom (S)

Measured in accordance with JIS K2541-6:2013.

＜Evaluation method＞

(I) Panel coking test

According to Federal test method 791B・3462, under the condition of panel temperature of 300°C and oil temperature of 100°C, the test was carried out for 3 hours with a cycle of splash time of 15 seconds and stop time of 45 seconds. After the end of the test, the weight (mg) of the coke adhering to the panel was measured.

(II) Oxidation stability

According to the ISOT test (165.5°C) of JIS K2514-1:2013, a copper piece and an iron piece are put into the test oil (lubricating oil composition) as a catalyst, and the test oil is forcibly deteriorated, and the base number after 96 hours is measured (perchloric acid method). The higher the value of the base number after the test, the higher the base number maintenance, and it is indicated as a long-lasting oil that can be used for a longer period of time. In addition, after the above-mentioned ISOT test, the n-pentane insoluble component was measured (A method).

(III) Shear stability

In accordance with JIS K2283:2000, the kinematic viscosity at 100° C. was measured before the test and after the shear test, and the shear stability was calculated from the following formula. In addition, the shear test was performed on the basis of the ultrasonic A method (JPI-5S-29-06), and was performed under the measurement conditions of ultrasonic irradiation time of 60 minutes, room temperature, and oil amount of 30 cc. The output voltage of the ultrasonic wave in the shear stability test was recorded as the output voltage at which the kinematic viscosity decrease rate at 100° C. was 25% after irradiating 30 cc of standard oil with ultrasonic waves for 10 minutes.

Shear stability (%)={([kinematic viscosity before test]-[kinematic viscosity after test])/[kinematic viscosity before test]}×100.

Embodiment 1～6 and comparative example 1～7

Lubricating oil compositions were prepared by blending the components shown in Tables 1 and 2, respectively. For the lubricating oil compositions prepared in each example and comparative example, on the basis of the determination of the acid value, 40°C kinematic viscosity, 100°C kinematic viscosity, calcium, nitrogen, phosphorus and sulfur content before various tests, the Tests shown in (I) to (III) above. These results are also presented together in the table.

[Table 1]

.

[Table 2]

.

Each compounding material of the said Example and a comparative example is as follows.

＜Compatible materials＞

(1) base oil

・Mineral oil classified as Group III of the API base oil category (kinematic viscosity at 40° C.: 18.9 mm ² /s, kinematic viscosity at 100° C.: 4.2 mm ² /s, viscosity index: 128).

(2) Olefin oligomers

ingredient (A)

・Oligomer 1: Polybutene-1 with a mass average molecular weight (Mw) of 940

・Oligomer 2: Polybutene-1 with a mass average molecular weight (Mw) of 2300

Olefin oligomers other than component (A)

・Oligomer 3: Decene oligomer with a mass average molecular weight (Mw) of 10,000

・Oligomer 4: Ethylene-propylene with a mass average molecular weight (Mw) of 12,000

- Oligomer 5: Ethylene-propylene having a mass average molecular weight (Mw) of 17,000.

(3) Antioxidant (B)

Phenolic antioxidant (B-1)

・Antioxidant (B-1-A): Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

・Antioxidant (B-1-B): Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]

Amine Antioxidant (B-2)

・Antioxidant (B-2-C): Monobutylphenylmonoctylphenylamine

・Antioxidant (B-2-D): N-p-tert-octylphenyl-1-naphthylamine.

(4) Alkaline earth metal-based detergent (C)

・Overbased calcium sulfonate (base value: 400 mgKOH/g, passed JISK 2501: 2003: Perchloric acid method).

(5) Zinc dithiophosphate (E)

・Zinc dihexyl dithiophosphate (n-hexyl).

(6) Other additives: sulfur-based extreme pressure agents, dispersants, ashless friction modifiers and defoamers.

As can be seen from Table 1, the lubricating oil compositions of Examples 1 to 6 have low kinematic viscosity at 100° C. and are excellent in heat resistance and oxidation stability. In addition, it was found that high molecular weight polymers such as viscosity index improvers that cause viscosity drop due to shearing are not required, so even after the shear test, the rate of viscosity drop was low, and the drop in viscosity when the actual vehicle was running was sufficiently suppressed.

On the other hand, from Table 2, the following are known. From Comparative Example 1, it can be seen that if the content in terms of calcium atoms of the component (C) based on the total amount of the lubricating oil composition is less than the present embodiment, the oxidation stability is poor. It can be seen that, as in Comparative Example 2, when the content of the component (C) in terms of calcium atoms based on the total amount of the lubricating oil composition is too high, the amount of sludge increases and the heat resistance is poor. It can be seen that, as in Comparative Examples 3 to 5, when an olefin oligomer having a mass average molecular weight outside the scope of the present application is used, the heat resistance is poor. In particular, in Comparative Example 5, an oligomer having a mass average molecular weight of 17,000 was used, so the shear stability was poor. As seen from Comparative Examples 6 and 7, when the antioxidant (B) is not used in combination with a phenolic antioxidant and an amine antioxidant, it is clear that the heat resistance is inferior.

Industrial Applicability

According to the present invention, it is possible to provide a lubricating oil composition that achieves low viscosity, suppresses a decrease in viscosity when an actual vehicle is running, and achieves improvements in heat resistance and oxidation stability accompanying downsizing and weight reduction of devices.

Claims (14)

1. lubricant oil composite, which is characterized in that while comprising base oil, including:

Matter average molecular weight be 500 or more and 5000 olefin oligomers (A) below,

Including the antioxidant (B) of phenolic antioxidant (B-1) and amine antioxidant (B-2) and

Alkaline-earth metal system detersive (C),

The content of alkaline-earth metal system detersive (C) counted by alkaline earth metal atom conversion is on the basis of the total amount of lubricant oil composite Be calculated as 1700 mass ppm or more and 2700 mass ppm hereinafter,

Kinematic viscosity at 100 DEG C is 4.0mm²/ s or more and 6.0mm²/ s or less.

2. lubricant oil composite according to claim 1, wherein the content of olefin oligomer (A) is with the lubricating oil group It is calculated as 0.8 mass % or more and 4.5 mass % or less on the basis of the total amount of conjunction object.

3. lubricant oil composite according to claim 1 or 2, wherein olefin oligomer (A) includes to be from carbon atom number The structural unit of 2 or more and 5 unsaturated hydrocarbon monomers below.

4. according to lubricant oil composite as claimed in any one of claims 1 to 3, wherein olefin oligomer (A) is polybutene.

5. the lubricant oil composite according to any one of claim 1 ~ 4, wherein alkaline-earth metal system detersive (C) is tool There is the alkali salt of 150mgKOH/g or more and 450mgKOH/g base numbers below.

6. the lubricant oil composite according to any one of claim 1 ~ 5, wherein alkaline-earth metal system detersive (C) is choosing From at least one kind of in alkaline earth metal sulfonate, alkaline earth phenate and alkaline earth metal salicylate.

7. the lubricant oil composite according to any one of claim 1 ~ 6, wherein the alkali of alkaline-earth metal system detersive (C) Earth metal atom is calcium atom or magnesium atom.

8. the lubricant oil composite according to any one of claim 1 ~ 7, wherein the content of antioxidant (B) is to lubricate 0.5 mass % or more and 3.0 mass % or less are calculated as on the basis of the total amount of fluid composition.

9. according to lubricant oil composite any one of claims 1 to 8, also contain zinc dithiophosphate (E).

10. according to lubricant oil composite any one of claims 1 to 9, it to be used for speed changer.

11. speed changer is filled with lubricant oil composite any one of claims 1 to 9.

12. lubricating method, wherein use the lubricant oil composite described in any one of claim 1 ~ 9.

13. the application method of lubricant oil composite any one of claims 1 to 9 in the transmission.

14. the manufacturing method of lubricant oil composite, is respectively cooperating with into base oil:Matter average molecular weight be 500 or more and 5000 with Under olefin oligomer (A), include the antioxidant (B) and alkali of phenolic antioxidant (B-1) and amine antioxidant (B-2) Earth metal system detersive (C), cooperation alkaline-earth metal system's detersive (C) is so that on the basis of the total amount of the lubricant oil composite It counts the content in terms of alkaline earth metal atom conversion and reaches 1700 mass ppm or more and 2700 mass ppm or less.