JP2021017559A - Lubricating oil additive and lubricating oil composition - Google Patents

Abstract

To provide a lubricating oil additive that is excellent in thick oil film forming capability and wear resistance.SOLUTION: A lubricating oil additive contains copolymer (A) that comprises, as essential constituent monomers, monomer (a) having an alicyclic structure, and monomer (b) represented by the following general formula (6). (R11 represents a hydrogen atom or a methyl group, X6 represents a group represented by -O- or -NH-, and R12O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer of 0 to 20, and when t is 2 or more, a plurality of R12O may be the same or different. R13 represents an alkyl group having 1 to 20 carbon atoms, and R14 represents an alkyl group having 1 to 20 carbon atoms.)SELECTED DRAWING: None

Description

The present invention relates to an additive for a lubricating oil and a lubricating oil composition.

Lubricating oils and hydraulic oils used in automobiles and the like have been reduced in viscosity in recent years in pursuit of fuel efficiency. The low viscosity reduces the frictional resistance in the fluid lubrication region and improves fuel efficiency, but causes problems such as liquid leakage and seizure.
In order to solve this problem, it is generally necessary to improve the oil film thickness of the lubricating oil and prevent the metal surface from being worn, and conventionally, cyclohexyl (meth) acrylates and alkyl (meth) having a linear alkyl group are required. ) Oil film improver (Patent Document 1) which is a copolymer of acrylate, long-chain fatty acid ester and fatty acid amide as oiliness improver, phosphoric acid ester as anti-wear agent, zinc dithiophosphate, organic as extreme pressure agent. Various additives such as sulfur, organic halogen compounds, and organic molybdenum compounds are used as friction control agents.
However, the above-mentioned lubricating oil additive has a problem that the oil film improving ability and the wear characteristics are not sufficient.

JP-A-61-238891

An object of the present invention is to provide a lubricating oil additive that imparts excellent oil film forming ability and wear characteristics to a lubricating oil composition.

The present inventors have arrived at the present invention as a result of studies for achieving the above object.
That is, in the present invention, the monomer (a1) represented by the following general formula (1), the monomer (a2) represented by the following general formula (2), the following general formula (3) or the general formula ( A group consisting of the monomer (a3) represented by 3'), the monomer (a4) represented by the following general formula (4), and the monomer (a5) represented by the following general formula (5). A monomer (a) having one or more alicyclic structures selected from the above, and a copolymer (A) containing the monomer (b) represented by the general formula (6) as an essential constituent monomer. Lubricating oil additive contained; and a lubricating oil composition containing this lubricating oil additive.

[R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a group represented by -O- or -NH-, and R ² independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n is an integer of 0 to 3, and m is an integer of 0 to 2. ]

[R ³ represents a hydrogen atom or a methyl group, X ² represents a group represented by -O- or -NH-, and R ⁴ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. j is an integer from 0 to 3. ]

[R ⁵ represents a hydrogen atom or a methyl group, X ³ represents a group represented by -O- or -NH-, and R ⁶ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. k is an integer from 0 to 3. ]

[R ⁷ represents a hydrogen atom or a methyl group, X ⁴ represents a group represented by -O- or -NH-, and R ⁸ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. p is an integer of 0 to 3, and q is an integer of 0 to 3. ]

[R ⁹ represents a hydrogen atom or a methyl group, X ⁵ represents a group represented by -O- or -NH-, and R ¹⁰ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. r is an integer of 0 to 3, and s is an integer of 0 to 1. ]

[R ¹¹ represents a hydrogen atom or a methyl group, X ⁶ represents a group represented by -O- or -NH-, and R ¹² O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer from 0 to 20, and when t is 2 or more, a plurality of R ¹² O may be the same or different. R ¹³ represents an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents an alkyl group having 1 to 20 carbon atoms. ]

The lubricating oil composition containing the lubricating oil additive of the present invention has an effect of being excellent in oil film forming ability and wear characteristics.

The lubricating oil additive of the present invention has a monomer (a1) represented by the following general formula (1), a monomer (a2) represented by the following general formula (2), the following general formula (3) or The monomer (a3) represented by the general formula (3'), the monomer (a4) represented by the following general formula (4), and the monomer (a5) represented by the following general formula (5). A copolymer (a) having one or more alicyclic structures selected from the group consisting of the above, and a monomer (b) represented by the general formula (6) as an essential constituent monomer. A) is contained.

[R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a group represented by -O- or -NH-, and R ² independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n is an integer of 0 to 3, and m is an integer of 0 to 2. ]

[R ³ represents a hydrogen atom or a methyl group, X ² represents a group represented by -O- or -NH-, and R ⁴ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. j is an integer from 0 to 3. ]

[R ⁵ represents a hydrogen atom or a methyl group, X ³ represents a group represented by -O- or -NH-, and R ⁶ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. k is an integer from 0 to 3. ]

[R ⁷ represents a hydrogen atom or a methyl group, X ⁴ represents a group represented by -O- or -NH-, and R ⁸ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. p is an integer of 0 to 3, and q is an integer of 0 to 3. ]

[R ⁹ represents a hydrogen atom or a methyl group, X ⁵ represents a group represented by -O- or -NH-, and R ¹⁰ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. r is an integer of 0 to 3, and s is an integer of 0 to 1. ]

[R ¹¹ represents a hydrogen atom or a methyl group, X ⁶ represents a group represented by -O- or -NH-, and R ¹² O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer from 0 to 20, and when t is 2 or more, a plurality of R ¹² O may be the same or different. R ¹³ represents an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents an alkyl group having 1 to 20 carbon atoms. ]

The copolymer (A), which is an essential component of the lubricating oil additive of the present invention, contains a monomer (a) having an alicyclic structure and a monomer (b) represented by the general formula (6). A copolymer as a monomer, the monomer (a) is a monomer (a1) represented by the general formula (1) and a single amount represented by the general formula (2). The body (a2), the monomer (a3) represented by the general formula (3) or the general formula (3'), the monomer (a4) represented by the general formula (4), and the general formula (a4). It is a monomer having one or more alicyclic structures selected from the group consisting of the monomer (a5) represented by 5).

Among the monomers (a) having an alicyclic structure as an essential constituent monomer of the copolymer (A) of the present invention, the monomer (a1) is represented by the above general formula (1).
X ¹ in the general formula (1) represents a group represented by -O- or -NH-.
R ¹ represents a hydrogen atom or a methyl group, R ² independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of R ² may be the same or different. n is an integer from 0 to 3.
m is an integer of 0 to 2, and represents a 5-membered ring when m = 0, a 6-membered ring when m = 1, and a 7-membered ring when m = 2.
Specific examples of the monomer (a1) include m = 0 {cyclopentyl (meth) acrylate, etc.}, m = 1 [n = 0 cyclohexyl (meth) acrylate, 2-, 3- or 4 -Methylcyclohexyl (meth) acrylate, 2,2-, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dimethylcyclohexyl (meth) acrylate, 2 , 2,3-, 2,2,4-, 2,2,5-, 2,2,6-, 3,3,4- or 3,3,5-, trimethylcyclohexyl (meth) acrylate, tetramethyl Cyclohexyl (meth) acrylate, pentamethylcyclohexyl (meth) acrylate, 2-, 3- or 4-t-butylcyclohexyl (meth) acrylate, N-cyclohexyl (meth) acrylamide, etc.}, n = 1 {(meth) Cyclomethylmethyl acrylate, etc.}, n = 2 {(meth) 2-cyclohexylethyl acrylate, etc.}, n = 3 {(meth) 3-cyclohexylpropyl acrylate, etc.}, etc.], m = 2 {(Meta) cycloheptyl acrylate, etc.} and the like can be mentioned.
Of these, cyclohexyl (meth) acrylate and 4-t-butylcyclohexyl (meth) acrylate are preferable from the viewpoint of oil film thickness forming ability.
As the monomer (a1), cyclohexyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., "light ester CH"), cyclohexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "Viscoat # 155, CHA"), 4 -T-Butylcyclohexylmethacrylate (manufactured by MCC Unitech Co., Ltd., manufactured by Tokyo Chemical Industry Co., Ltd.), 4-t-butylcyclohexylacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), etc. are commercially available and available. ..

The monomer (a2) is represented by the above general formula (2).
X ² in the general formula (2) represents a group represented by -O- or -NH-.
R ³ represents a hydrogen atom or a methyl group, R ⁴ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of R ⁴ may be the same or different. j is an integer from 0 to 3.
Specific examples of the monomer (a2) include isobornyl (meth) acrylate and the like.
In addition, isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), isobornyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and the like are commercially available and available.

The monomer (a3) is represented by the above general formula (3) or general formula (3').
X ³ in the general formula (3) and the general formula (3') represents a group represented by -O- or -NH-.
R ⁵ represents a hydrogen atom or a methyl group, R ⁶ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of R ⁶ may be the same or different. k is an integer from 0 to 3.
Specific examples of the monomer (a3) include dicyclopentanyl (meth) acrylate and the like.
In addition, dicyclopentanyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), dicyclopentanyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and the like are commercially available and available.

The monomer (a4) is represented by the above general formula (4).
X ⁴ in the general formula (4) represents a group represented by -O- or -NH-.
R ⁷ represents a hydrogen atom or a methyl group, R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, plurality is R ⁸ may be the same or different. p is an integer of 0 to 3, q is an integer of 0 to 3, a 3-membered ring when q = 0, a 4-membered ring when q = 1, a 5-membered ring when q = 2, and q. When = 3, it represents a 6-membered ring.
Specific examples of the monomer (a4) include glycidyl (meth) acrylate and tetrahydrofurfuryl (meth) acrylate.
In addition, glycidyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), tetrahydrofurfuryl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), tetrahydrofurfuryl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), etc. are commercially available and available. Is.

The monomer (a5) is represented by the above general formula (5).
X ⁵ in the general formula (5) represents a group represented by -O- or -NH-.
R ⁹ represents a hydrogen atom or a methyl group, R ¹⁰ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of R ^10s may be the same or different. r is an integer of 1 to 3, s is an integer of 0 to 1, and when s = 0, it represents a 5-membered ring including dioxo, and when s = 1, it represents a 6-membered ring.
Specific examples of the monomer (a5) include (2-methyl-2-ethyl-1,3-dioxolane-4-yl) methyl (meth) acrylate and (meth) acrylic acid (5-ethyl-1,3). -Dioxane-5-yl) Methyl and the like can be mentioned.
In addition, (2-methyl-2-ethyl-1,3-dioxolane-4-yl) methyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "MEDOL-10"), acrylic acid (5-ethyl-1,3) -Dioxane-5-yl) Methyl (manufactured by Tokyo Chemical Industry Co., Ltd.), Acrylic acid (5-ethyl-1,3-dioxane-5-yl) methyl (manufactured by Osaka Organic Chemical Industry Co., Ltd.), "Viscort # 200"") Etc. are commercially available and available.

One of these monomers (a) having an alicyclic structure may be used alone, or two or more thereof may be used in combination.

The essential constituent monomer (b) of the copolymer (A) of the present invention is a monomer represented by the above general formula (6), and R ¹³ in the general formula (6) has 1 to 1 carbon atoms. It is an alkyl group of 20 and R ¹⁴ is an alkyl group having 1 to 20 carbon atoms.
In R ^13, the alkyl group having 1 to 20 carbon atoms, a methyl group, an ethyl group, n- propyl group, n- butyl group, n- pentyl group, n- hexyl, n- heptyl, n- octyl group , N-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group. , Linear alkyl groups such as n-nonadesyl group and n-eicosyl group, branched alkyl groups such as isopropyl group, isobutyl group, 2-ethylhexyl group, isononyl group and isodecyl group.
In R ^14, the alkyl group having 1 to 20 carbon atoms and having 1 to 20 carbon atoms among the alkyl groups described above having 1 to 20 carbon atoms.
The R ^13, oil film thickness forming ability, wear characteristics, from the viewpoint of low-temperature viscosity characteristics and friction reducing effect, is preferably an alkyl group having 1 to 15 carbon atoms.
The R ^14, oil film thickness forming ability, wear characteristics, from the viewpoint of low-temperature viscosity characteristics and friction reducing effect, preferably an alkyl group having a carbon number of 7-20.
Sum of the number of carbon atoms of the number and ^{R 14} of carbon atoms of R ¹³ is an oil film thickness forming, wear characteristics, from the viewpoint of low-temperature viscosity characteristics and friction reducing effect, preferably 8-32, more preferably from 20 to 24.
In the copolymer (A), one type may be used alone as the monomer (b), or two or more types may be used in combination.

Among the constituent monomers of the copolymer (A), the content of the monomer (a) is the content of the monomer (a) and the monomer (b) from the viewpoint of oil film forming ability and wear characteristics. Based on the total weight, it is preferably 1 to 90% by weight, more preferably 1 to 70% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (a) is the monomer (a) and the monomer from the viewpoint of oil film forming ability, abrasion characteristics and low temperature viscosity characteristics. Based on the total weight of (b), it is preferably 1 to 40% by weight, more preferably 1 to 25% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (a) is the monomer (a) and the monomer from the viewpoint of oil film forming ability, wear characteristics and friction reducing effect. Based on the total weight of (b), it is preferably 10 to 90% by weight, more preferably 30 to 70% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (b) is the content of the monomer (a) and the monomer (b) from the viewpoint of oil film forming ability and wear characteristics. Based on the total weight, it is preferably 10 to 99% by weight, more preferably 30 to 99% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (b) is the monomer (a) and the monomer from the viewpoint of oil film forming ability, abrasion characteristics and low temperature viscosity characteristics. Based on the total weight of (b), it is preferably 60 to 99% by weight, more preferably 75 to 99% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (b) is determined from the viewpoint of oil film forming ability, wear characteristics, friction reducing effect, and solubility of (A) in the base oil. , It is preferably 10 to 90% by weight, more preferably 30 to 70% by weight, based on the total weight of the monomer (a) and the monomer (b).

The copolymer (A) of the present invention further has an alkyl group having 1 to 4 carbon atoms as a constituent monomer of (A) in addition to the monomer (a) and the monomer (b) (meth). ) Acrylic acid alkyl ester (d) may be contained.
Examples of the alkyl group having 1 to 4 carbon atoms in the (meth) acrylic acid alkyl ester (d) include a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group and an n-butyl group, an isopropyl group and an isobutyl group. And branched alkyl groups such as t-butyl group and the like.
The (meth) acrylic acid alkyl ester (d) is preferably methyl (meth) acrylic acid from the viewpoint of low-temperature viscosity characteristics.
The (meth) acrylic acid alkyl ester (d) having an alkyl group having 1 to 4 carbon atoms may be used alone or in combination of two or more.
Of the constituent monomers of the copolymer (A), the content of the (meth) acrylic acid alkyl ester (d) is preferably 1 to 20% by weight based on the weight of the copolymer (A). , More preferably 1 to 10% by weight.
The content of the (meth) acrylic acid alkyl ester (d) can be quantitatively measured by analyzing the copolymer (A) by thermal decomposition gas chromatography.

The weight average molecular weight of the copolymer (A) (hereinafter, may be abbreviated as Mw) is preferably 1,000 to 500,000 from the viewpoint of friction reducing effect, low temperature viscosity characteristics and shear stability. It is more preferably 1,000 to 100,000, further preferably 1,000 to 50,000, and most preferably 1,000 to 25,000. When Mw of (A) is 1,000 or more, the friction reducing effect tends to be good, and when it is 500,000 or less, shear stability, low temperature viscosity characteristics and viscosity characteristics tend to be good.
Mw is obtained by gel permeation chromatography and is obtained by converting it into polystyrene.
The measurement conditions for Mw of the copolymer (A) are as follows.
Equipment: "HLC-802A" [manufactured by Tosoh Corporation]
Column: 2 "TSK gel GMH6" [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C
Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection volume: 100 μl
Detector: Refractive index detector Reference material: Standard polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400 , 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]
The Mw of the copolymer (A) can be adjusted by the temperature at the time of polymerization, the monomer concentration (solvent concentration), the amount of catalyst, the amount of chain transfer agent, and the like.

The solubility parameter of the copolymer (A) (hereinafter sometimes abbreviated as “SP value”) is 7.3 to 9.6 (cal / cm ³ ) ^{1 /} from the viewpoint of solubility in lubricating oil. ² is preferable, and more preferably 8.8 to 9.5 (cal / cm ³ ) ^1/2 .

The SP value in the present invention is a value calculated by the method described in the Fedors method (Polymer Engineering and Science, February, 1974, Vol. 14, No. 2 P. 147 to 154).

The copolymer (A) can be obtained by a known production method, and specific examples thereof include a method obtained by solution-polymerizing the above-mentioned monomer in a solvent in the presence of a polymerization catalyst.
As the solvent, an organic solvent such as toluene, xylene, alkylbenzene having 9 to 10 carbon atoms, methyl ethyl ketone, ethyl acetate and 2-propanol;
Mineral oils (refined solvent oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil by hydrocracking of isoparaffin, naphthenic oil, etc.) and synthetic lubricating oil [hydrocarbon synthetic lubricating oil (poly α-olefin) Base oils such as synthetic lubricating oils, etc.) and ester synthetic lubricating oils, etc.] can be mentioned.
The solvent is preferably a base oil, more preferably a mineral oil.
Examples of the polymerization catalyst include azo catalysts (azobisisobutyronitrile, azobisvaleronitrile, etc.), peroxide catalysts (benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.), and redox catalysts (benzoyl peroxide, etc.). And a mixture of tertiary amines, etc.). Further, if necessary, a known chain transfer agent (alkyl mercaptan having 2 to 20 carbon atoms, etc.) can be used.
The polymerization temperature is preferably 25 to 140 ° C, more preferably 50 to 120 ° C. In addition to the above solution polymerization, (A) can be obtained by bulk polymerization, emulsion polymerization or suspension polymerization.
When (A) is a copolymer, the polymerization form may be either a random polymer or an alternating copolymer, or may be a graft copolymer or a block copolymer.

The lubricating oil additive of the present invention contains the above-mentioned copolymer (A), and may further contain a base oil (I). When the base oil (I) is used as a solvent for producing the copolymer (A), the mixture containing the obtained copolymer (A) and the base oil (I) is used as a lubricating oil additive as it is. You may use it. Further, the obtained mixture diluted with the base oil (I) may be used as a lubricating oil additive.

From the viewpoint of handleability, the content of the copolymer (A) in the lubricating oil additive is preferably 40 to 100% by weight, more preferably 40 to 60% by weight, based on the weight of the lubricating oil additive. %.

The base oil (I) includes mineral oils (refined solvent oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil by hydrocracking of isoparaffin, naphthenic oil, etc.), synthetic lubricating oil [hydrocarbon-based Synthetic lubricating oils (poly-α-olefin-based synthetic lubricating oils, etc.) and ester-based synthetic lubricating oils, etc.] and mixtures thereof can be mentioned. Of these, mineral oils and ester-based synthetic lubricating oils are preferable, and mineral oils are more preferable.
The base oil (I) may be used alone or in combination of two or more.

(Measured by JIS-K2283) kinematic viscosity at 100 ° C. of the base oil (I) is preferably from the viewpoint of the viscosity index improving effect is 1 to 15 mm ² / s, more preferably at 2 to 5 mm ² / s is there.
The viscosity index of the base oil (measured by JIS-K2283) is preferably 90 or more, and more preferably 100 or more.

The cloudiness point of the base oil (measured by JIS-K2269) is preferably −5 ° C. or lower, and more preferably −15 ° C. or lower. When the cloudiness point of the base oil is within this range, the low temperature viscosity of the lubricating oil composition is good.

The SP value of the base oil (I) is preferably 7.8 to 9.3 (cal / cm ³ ) ^1/2 , more preferably 8.0 to 8.5 (cal / cm ³ ) ^1/2 .

The lubricating oil additive of the present invention can impart excellent oil film forming ability and wear characteristics to the lubricating oil composition, and also has low temperature viscosity characteristics and a friction reducing effect in the low to medium temperature range (40 to 80 ° C.). Since it is excellent, it can be used as a friction and wear modifier, an oiliness improver, and the like.

The lubricating oil composition of the present invention contains the above-mentioned lubricating oil additive of the present invention.
The content of the copolymer (A) in the lubricating oil composition of the present invention is preferably based on the weight of the lubricating oil composition from the viewpoints of oil film forming ability, wear characteristics, low temperature viscosity characteristics and friction reducing effect. It is 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, and particularly preferably 1 to 10% by weight.

Kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 1 to 15 mm ² / s, more preferably from 2 to 5 mm ² / s.
The viscosity index of the lubricating oil composition of the present invention is preferably 90 or more, more preferably 100 or more.

In the lubricating oil composition, the absolute value of the difference between the SP value of the copolymer (A) and the SP value of the base oil (I) is 0.5 from the viewpoint of the solubility of (A) in (I). It is preferably ~ 3.0 (cal / cm ³ ) ^1/2 , and more preferably 0.8 to 1.6 (cal / cm ³ ) ^1/2 .
When two or more kinds of base oils (I) are used in combination, the calculated value of the arithmetic mean based on the weight ratios of the base oils as a mixture is used as the SP value.

The lubricating oil composition of the present invention includes gear oil (differential oil, industrial gear oil, etc.), transmission gear oil (MTF), transmission oil [ATF and belt-CVTF, etc.], traction oil (toroidal-CVTF, etc.), shock. It is suitably used for absorber oil, power steering oil, hydraulic oil (hydraulic oil for construction machinery, industrial oil, etc.), engine oil, and the like. Of these, gear oils, MTFs, transmission oils, traction oils and engine oils are preferred, further preferred are differential oils, MTFs, ATFs, belt-CVTFs and engine oils, with particular preference being MTFs, ATFs. , Belt-CVTF and engine oil.

The lubricating oil composition of the present invention further comprises a viscosity index improver, a cleaning agent, a dispersant, an antioxidant, an oiliness improver, an extreme pressure agent, an antifoaming agent, an anti-emulsifier, a corrosion inhibitor and a pour point lowering agent. It may contain one or more additives selected from the group. Specific examples of the additive include the following.
(1) Viscosity index improver:
C (hereinafter, the number of carbon atoms is abbreviated as C) 1 to 7 alkyl (meth) acrylate / C8 to 40 linear or branched alkyl (meth) acrylate copolymer, dispersed monomer (amine monomer, etc.) / C1 to 7 Alkyl (meth) acrylate / C8-40 linear or branched alkyl (meth) acrylate copolymer, hydroxy group-containing monomer / (C1-7) alkyl (meth) acrylate / C8-40 linear or branched alkyl (Meta) acrylate copolymer, comb polymer [alkyl (meth) acrylate of C1-7 / linear or branched alkyl (meth) acrylate / polyolefin macromonomer of C8-40], alkyl (meth) of ethylene / C1-18 Acrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymer, styrene / maleic acid ester copolymer, styrene / isoprene hydride copolymer, etc.;
(2) Cleaner:
Basic, hyperbasic or neutral metal salts [superbasic or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzenesulfonates, alkylnaphthalensulfonates, etc.)], salicylates, phenates, naphthenates, etc. Classes, carbonates, phosphonates and mixtures thereof;
(3) Dispersant:
Imides succinate (bis- or mono-polybutenyl succinate imides), Mannich condensates, borates, etc .;
(4) Antioxidant:
Hindered phenols and aromatic secondary amines, etc .;
(5) Oiliness improver:
Long chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long chain amines and their amides (oleylamine, oleylamide, etc.), etc .;
(6) Friction wear modifier:
Molybdenum-based and zinc-based compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, etc.), etc.;
(7) Extreme pressure agent:
Sulfur-based compounds (mono or disulfide, sulfoxide and sulfur phosphide compounds), phosphofide compounds and chlorinated compounds (chlorinated paraffin, etc.), etc.;
(8) Defoamer:
Silicone oil, metal soap, fatty acid ester, phosphate compound, etc .;
(9) Anti-emulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphates (polyoxyethylene-containing nonionic surfactants, etc.);
(10) Corrosion inhibitor:
Nitrogen atom-containing compounds (benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate, etc.);
(11) Pour point depressant:
Polyalkyl methacrylate, polyalkyl acrylate, polyalkyl styrene, polyvinyl acetate, etc.

The total content of the additives is preferably 0.1 to 20% by weight, more preferably 0, based on the weight of the lubricating oil composition from the viewpoint of oil film forming ability, wear characteristics, low temperature viscosity characteristics and friction reducing effect. .1 to 10% by weight.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified,% indicates a weight% and a part indicates a weight part.

Examples 1-9 and Comparative Examples 1-4
Mineral oil (I-1) (“Ultra S-2” manufactured by S-Oil, kinematic viscosity at 100 ° C.: 2.3 mm ² ) in a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer and a nitrogen introduction tube. / S, Viscosity index: 103) 40 parts, 60 parts of the formulations of various monomers (a) to (d) shown in Table 1, 2,2'-azobis (2,4-dimethylvaleronitrile) 0. After adding 5 parts by weight and 0.2 parts by weight of 2,2'-azobis (2-methylbutyronitrile) and performing nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature is 76 ° C. with stirring under sealing. The temperature was raised to 3 and the polymerization reaction was carried out at the same temperature for 5 hours. Then, the temperature was further raised to 90 ° C. and aged for 1 hour. After raising the temperature to 120 ° C., the unreacted monomer was removed over 2 hours under reduced pressure (0.027 to 0.040 MPa) at the same temperature, and the lubricating oil additives (R-1) to (R-1) of the present invention were removed. R-9) and lubricating oil additives (R'-1) to (R'-4) for comparison were produced.

The following monomers were used as the various monomers (a) to (d) shown in Table 1 and Table 3 below.
(A1-1): Cyclohexyl methacrylate (a1-2): 4-t-butylcyclohexyl methacrylate (a2-1): Isobornyl methacrylate (a3-1): Dicyclopentanyl methacrylate (a4-1): Tetrahydroflu Frill methacrylate (a5-1): Acrylic acid (5-ethyl-1,3-dioxane-5-yl) methyl ("Viscoat # 200" manufactured by Osaka Organic Industry Co., Ltd. "
(B-1): R ¹³ is a methyl group in the general formula (6), an aliphatic alcohol R ¹⁴ is a linear alkyl group having 8 to 10 carbon atoms, R ¹³ is an ethyl group general formula (6), R A mixture of a linear alkyl group having ¹⁴ having 8 to 10 carbon atoms with an aliphatic alcohol [ester of a higher alcohol "NEODOL 23" manufactured by Shell Chemicals) and a methacrylic acid).
(B-2): R ¹³ is a methyl group in the general formula (6), aliphatic alcohol of a straight chain alkyl group R ¹⁴ is a 10 to 12 carbon atoms, R ¹³ is an ethyl group general formula (6), R Ester (b-3) of a mixture of a linear alkyl group having ¹⁴ having 10 to 12 carbon atoms with an aliphatic alcohol [higher alcohol "NEODOL 45" manufactured by Shell Chemicals] and methacrylic acid: 2-dodecylhexadecyl methacrylate. (b-4): methacrylic acid 2-tetradecyl-octadecyl (b-5): straight-chain alkyl group ^{R 13} in the general formula (6) is 10 carbon ^{atoms, R 14} is a straight-chain alkyl group of 12 carbon atoms fat Ester of group alcohol [Sosol's higher alcohol "ISOFOL 24"] and methacrylic acid (b'-1): n-dodecyl methacrylate (b'-2): n-hexadecyl methacrylate (d-1): methacrylic acid Methyl (I-1): "Ultra S-2" manufactured by S-Oil
(I-2): "YUBASE4" manufactured by SK
The SP value and weight average molecular weight (Mw) of the copolymer (A) are shown in Tables 1 and 3.

Examples 10-18 and Comparative Examples 5-8
Lubricating oil additives (R-1) to (R-9) obtained in Examples 1 to 9 and lubricating oil additives (R'-1) to for comparison obtained in Comparative Examples 1 to 4 (R'-4) is a mineral oil (I-2) (“YUBASE3” manufactured by SK, 100 ° C. kinematic viscosity 3.1 mm ² / s, viscosity index: 112), and 100 ° C. kinematic viscosity is 5.4 mm ² Dilute to / s, and use the lubricating oil compositions (V-1) to (V-9) of the present invention and the lubricating oil compositions (V'-1) to (V'-4) for comparison. Obtained.

Lubricating oil compositions (V-1) to (V-9) of the present invention prepared in Examples 10 to 18, and lubricating oil compositions for comparison (V'-1) prepared in Comparative Examples 5 to 8. ~ (V'-4) was evaluated by measuring (1) oil film forming ability, (2) wear characteristics, and (3) low temperature viscosity characteristics by the following methods. The results are shown in Table 2.

<Oil film thickness forming ability>
The oil film thickness (nm) at a constant load and slip rate was calculated by the optical interferometry using an EHD tester (manufactured by PCS Instruments), and the oil film thickness forming ability of each lubricating oil composition was evaluated. ..
The test conditions of the EHD tester are shown below.
Disc: EHD Silicon Spacer Layer Disc
Ball: 3/4''Plan Steel Ball
Load: 30N
Ball speed: 10 mm to 3,000 mm / s Temperature: 100 ° C
Slip rate: 50%
A curve is obtained from the oil film thickness at each speed in the range of 10 mm to 3,000 mm / s, and the oil film thickness (nm) at 10 mm / s is used as the measurement result.

The measured oil film thickness (nm) was evaluated according to the following criteria.
⊚: 6 nm or more ○: 4 to 6 nm
Δ: 2 to 4 nm
×: Less than 2 nm

<Abrasion characteristics>
A high-frequency reciprocating rig test was conducted under the following conditions, and wear characteristics were evaluated from the wear mark diameter.
As an apparatus, High-Frequency-Reciprocating-Rig (HFRR; manufactured by PCS Instruments) was used, the material of the test steel ball was SUJ2, the diameter of the test steel ball was 6 mm, and the material of the test disk was SUJ2. The test was carried out at a load of 3.92 N (400 g), a stroke of 1000 μm, a frequency of 20 Hz, a test time of 60 minutes, and a temperature of 100 ° C., and the wear mark diameter was measured.

The wear marks were evaluated according to the following criteria.
⊚: Wear scar diameter is 180 μm or less ◯: Wear scar diameter is 180 to 200 μm
Δ: Wear scar diameter is 200 to 230 μm
X: Wear scar diameter exceeds 230 μm

<Low temperature viscosity characteristics>
Brookfield viscosity (BF) (mPa · s) at −40 ° C. was measured according to the method of ASTM D2983-2001.

It was evaluated from the Brookfield viscosity (mPa · s) according to the following criteria.
⊚: 5000 mPa · s or less ○: 5000-7000 mPa · s
Δ: 7,000 to 10,000 mPa · s
×: Over 10000 mPa · s

As is clear from the results in Table 2, the lubricating oil compositions of Examples 10 to 18 containing the lubricating oil additive of the present invention are excellent in film thickness forming ability and wear characteristics, and further have low temperature viscosity characteristics. Is excellent.
On the other hand, it can be seen that the lubricating oil composition of Comparative Example 5 containing the copolymer not containing the monomer (a) as the constituent monomer has poor oil film forming ability and wear characteristics. Further, the monomer (b'-1) and / or (b'-) in which the monomer (b) is not used in Example 11 (R ¹³ of the general formula (6) is a hydrogen atom instead of an alkyl group). Comparing with Comparative Examples 6 to 8 which are the same except for (2)), Comparative Example 6 (using n-dodecyl methacrylate) has both oil film forming ability and abrasion characteristics as compared with Example 11. It turns out to be inferior. Further, in Comparative Example 7 (using n-hexadecyl methacrylate) having a longer carbon number than that of Comparative Example 6, the oil film forming ability was about the same as that of Example 11, but the wear characteristics were good. It turns out that is extremely inferior. Further, it can be seen that Comparative Example 8 in which those having different carbon atoms are used in combination is inferior in oil film forming ability and wear characteristics as compared with Example 11. That is, when a monomer (b') in which R ^{13 of} the general formula (6) is a hydrogen atom instead of an alkyl group is used, a lubricating oil composition having excellent oil film forming ability and wear characteristics can be obtained. Turns out to be difficult. Further, it can be seen that Comparative Examples 6 to 8 are extremely inferior in low temperature viscosity characteristics.

Examples 19-28 and Comparative Examples 9-11
Mineral oil (I-2) (SK's "YUBASE3", 100 ° C. kinematic viscosity 3.1 mm ² / s, viscosity index: 112) in a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer and a nitrogen introduction tube. ) 50 parts, 50 parts of the formulations of various monomers (a) to (d) shown in Table 3, 0.5 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2. After adding 0.2 parts by weight of'-azobis (2-methylbutyronitrile) and performing nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76 ° C. with stirring under airtightness to the same temperature. The polymerization reaction was carried out for 5 hours. Then, the temperature was further raised to 90 ° C. and aged for 1 hour. After raising the temperature to 120 ° C., the unreacted monomer was removed over 2 hours under reduced pressure (0.027 to 0.040 MPa) at the same temperature, and the lubricating oil additive (R-10) to (R-10) of the present invention ( R-19) and lubricating oil additives (R'-5) to (R'-7) for comparison were produced.

Examples 29-38 and Comparative Examples 12-14
In a stainless steel container equipped with a stirrer, 10 parts by weight of an additive package for engine oil (manufactured by Infinium) and mineral oil [SP value: 8.3 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C. : 4.2 mm ² / s, viscosity index: 122] 90 parts by weight were added, and the lubricating oil additives (R-10) to (R-19) obtained in Examples 10 to 19 and Comparative Examples 9 to 9 to Lubricating oil additives (R'-5) to (R'-7) for comparison obtained in No. 11 are further added so that the content of the copolymer (A) is 1% by weight, respectively. A viscosity index improver (polyalkyl methacrylate, Mw 500,000, resin content 21% by weight) was added so that the HTHS viscosity at 150 ° C. of the oil composition was 2.60 ± 0.05 (mm ² / s). Mixing was performed to obtain lubricating oil compositions (V-10) to (V-19) of the present invention and lubricating oil compositions (V'-5) to (V'-7) for comparison.

Lubricating oil compositions of the present invention prepared in Examples 29 to 38 (V-10) to (V-19), and lubricating oil compositions for comparison prepared in Comparative Examples 12 to 14 (V'-5). ~ (V'-7) was evaluated by measuring (1) oil film forming ability and (2) wear characteristics by the above method. In addition, (3) MTM friction coefficient was measured and evaluated by the following method. The results are shown in Table 4.

Lubricating oil compositions (V-10) to (V-19) and (V'-5) to (V'-7) under low to medium temperature conditions at 40 ° C, 60 ° C and 80 ° C. Friction evaluation was measured by the following method. The results are shown in Table 4.
<Rolling friction characteristics-MTM (coefficient of friction)>
Equipment: PCS Instruments MTM-2
Disc: MTM polished disc (standard) (0.01 micron)
Ball: Drilled 3/4 AISI52100 precision steel ball
Speed: 10 mm / s to 3,000 mm / s
Temperature: 40 ° C, 60 ° C, 80 ° C
Sliding / rolling ratio: 50%
Load: 30N
A Stribeck curve was obtained as a result of the friction evaluation, and the friction coefficients of the velocities at each temperature: 10 mm / s, 100 mm / s, and 1,000 mm / s were used as the measurement results.

As is clear from the results in Table 4, the lubricating oil compositions of Examples 29 to 38 containing the lubricating oil additive of the present invention are excellent in film thickness forming ability and wear characteristics, and further have a friction reducing effect. Is excellent.
On the other hand, it can be seen that the lubricating oil composition of Comparative Example 12 containing the copolymer not containing the monomer (a) as the constituent monomer has poor oil film forming ability and wear characteristics. Further, the monomer (b'-1) and / or (b'-) in which the monomer (b) of Example 33 is not used (R ¹³ of the general formula (6) is a hydrogen atom instead of an alkyl group). Comparing with Comparative Examples 13 and 14 which are the same except for (2)), Comparative Example 13 (using n-dodecyl methacrylate) has both oil film forming ability and abrasion characteristics as compared with Example 33. It turns out to be inferior. Further, in Comparative Example 14 (using n-hexadecyl methacrylate) using a material having a longer carbon number than that of Comparative Example 13, although the oil film forming ability was as good as that of Example 33, the wear characteristics were good. It turns out that is inferior. That is, when a monomer (b') in which R ^{13 of} the general formula (6) is a hydrogen atom instead of an alkyl group is used, a lubricating oil composition having excellent oil film forming ability and wear characteristics can be obtained. Turns out to be difficult. Further, it can be seen that Comparative Examples 13 to 14 are extremely inferior in the friction reducing effect.

The lubricating oil composition of the present invention is excellent in oil film forming ability and wear characteristics, and is also excellent in low temperature viscosity characteristics and friction reducing effect in low temperature to medium temperature range (40 to 80 ° C.). It is suitable as MTF, differential gear oil, ATF and belt-CVTF, etc.), hydraulic oil (machine hydraulic oil, power steering oil, shock absorber oil, etc.), engine oil (for gasoline and diesel, etc.) and traction oil.

Claims (5)

It is represented by the monomer (a1) represented by the following general formula (1), the monomer (a2) represented by the following general formula (2), the following general formula (3) or the general formula (3'). One or more selected from the group consisting of the monomer (a3), the monomer (a4) represented by the following general formula (4), and the monomer (a5) represented by the following general formula (5). Lubricating oil additive containing a monomer (a) having an alicyclic structure and a copolymer (A) containing the monomer (b) represented by the general formula (6) as an essential constituent monomer. ..

[R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a group represented by -O- or -NH-, and R ² independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n is an integer of 0 to 3, and m is an integer of 0 to 2. ]

[R ³ represents a hydrogen atom or a methyl group, X ² represents a group represented by -O- or -NH-, and R ⁴ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. j is an integer from 0 to 3. ]

[R ⁵ represents a hydrogen atom or a methyl group, X ³ represents a group represented by -O- or -NH-, and R ⁶ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. k is an integer from 0 to 3. ]

[R ⁷ represents a hydrogen atom or a methyl group, X ⁴ represents a group represented by -O- or -NH-, and R ⁸ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. p is an integer of 0 to 3, and q is an integer of 0 to 3. ]

[R ⁹ represents a hydrogen atom or a methyl group, X ⁵ represents a group represented by -O- or -NH-, and R ¹⁰ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. r is an integer of 0 to 3, and s is an integer of 0 to 1. ]

[R ¹¹ represents a hydrogen atom or a methyl group, X ⁶ represents a group represented by -O- or -NH-, and R ¹² O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer from 0 to 20, and when t is 2 or more, a plurality of R ¹² O may be the same or different. R ¹³ represents an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents an alkyl group having 1 to 20 carbon atoms. ] The lubricating oil additive according to claim 1, wherein the copolymer (A) has a weight average molecular weight of 1,000 to 500,000. The lubricating oil additive according to claim 1 or 2, further comprising a base oil (I). A lubricating oil composition containing the lubricating oil additive according to any one of claims 1 to 3. Further, one or more additions selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, extreme pressure agents, defoamers, anti-emulsifiers, corrosion inhibitors and pour point lowering agents. The lubricating oil composition according to claim 4, which comprises an agent.