JP7256768B2 - Lubricating oil additive and lubricating oil composition - Google Patents

Description

The present invention relates to lubricating oil additives and lubricating oil compositions.

In recent years, the viscosity of lubricating oils and hydraulic oils used in automobiles and the like has been decreasing due to the pursuit of fuel efficiency. While reducing the viscosity reduces frictional resistance in the fluid lubrication region and improves fuel efficiency, it also 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 abrasion of the metal surface. ) An oil film improver (Patent Document 1) that is an acrylate copolymer, a long-chain fatty acid ester or fatty acid amide as an oiliness improver, a phosphate ester or zinc dithiophosphate as an antiwear agent, an organic Various additives such as sulfur, organic halogen compounds, and organic molybdenum compounds as friction control agents are used.
However, the lubricating oil additive described above has a problem that the oil film improving ability and the wear property are not sufficient.

JP-A-61-238891

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

The present inventors arrived at the present invention as a result of conducting studies to achieve the above object.
That is, the present invention provides 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 a general formula ( 3′), a group consisting of a monomer (a4) represented by the following general formula (4) and a monomer (a5) represented by the following general formula (5) A monomer (a) having one or more alicyclic structures selected from and a copolymer (A) having as essential constituent monomers a monomer (b) represented by the general formula (6) The lubricating oil additive contained, wherein the total weight ratio of the monomer (a) and the monomer (b) in the constituent monomers of the copolymer (A) is that of the copolymer (A) A lubricating oil additive that is 80% or more by weight based on the total weight of the constituent monomers ; and a lubricating oil composition containing the 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 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n is an integer of 0-3, m is an integer of 0-2. ]

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

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

[R ¹¹ represents a hydrogen atom or a methyl group, X ⁶ represents a group represented by —O 2 — , and R ¹² O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer of 0 , R ¹³ represents an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents an alkyl group having 8 to 20 carbon atoms. ]

A lubricating oil composition containing the lubricating oil additive of the present invention has the effect of being excellent in oil film-forming ability and wear properties.

The lubricating oil additive of the present invention includes 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 A monomer (a3) represented by the general formula (3′), a monomer (a4) represented by the following general formula (4) and a monomer (a5) represented by the following general formula (5) A monomer (a) having one or more alicyclic structures selected from the group consisting of a copolymer ( A).

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

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

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

[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 of 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, comprises a monomer (a) having an alicyclic structure and a monomer (b) represented by the general formula (6). A copolymer as a monomer, wherein the monomer (a) is a monomer (a1) represented by the general formula (1), and a monomer represented by the general formula (2) Body (a2), the monomer (a3) represented by the general formula (3) or general formula (3′), the monomer (a4) represented by the general formula (4) and the general formula ( 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 essential constituent monomers of the copolymer (A) of the present invention, the monomer (a1) is represented by the general formula (1).
X ¹ in general formula (1) represents a group represented by -O- or -NH-.
R ¹ represents a hydrogen atom or a methyl group, each 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 of 0-3.
m is an integer of 0 to 2, where m=0 represents a 5-membered ring, m=1 represents a 6-membered ring, and m=2 represents a 7-membered ring.
Specific examples of the monomer (a1) include those with m = 0 {cyclopentyl (meth) acrylate, etc.}, those with m = 1 [cyclohexyl (meth) acrylate with n = 0, 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) Cyclohexylmethyl acrylate, etc.}, n=2 {2-cyclohexylethyl (meth)acrylate, etc.}, n=3 {3-cyclohexylpropyl (meth)acrylate, etc.}, m=2 {(meth)acrylic acid cycloheptyl etc.} etc. are mentioned.
Among these, cyclohexyl (meth)acrylate and 4-t-butylcyclohexyl (meth)acrylate are preferred from the viewpoint of oil film forming ability.
As the monomer (a1), cyclohexyl methacrylate ("Light Ester CH" manufactured by Kyoeisha Chemical Co., Ltd.), cyclohexyl acrylate ("Viscoat #155, CHA" manufactured by Osaka Organic Chemical Industry Co., Ltd.), 4 -t-butyl cyclohexyl methacrylate (manufactured by MCC Unitec Co., Ltd., Tokyo Chemical Industry Co., Ltd.), 4-t-butyl cyclohexyl acrylate (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 general formula (2) represents a group represented by -O- or -NH-.
R ³ represents a hydrogen atom or a methyl group, each 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.
Isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), isobornyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and the like are commercially available.

The monomer (a3) is represented by the above general formula (3) or general formula (3').
X ³ in general formulas (3) and (3′) represents a group represented by —O— or —NH—.
R ⁵ represents a hydrogen atom or a methyl group, each 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.
Dicyclopentanyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), dicyclopentanyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and the like are commercially available.

The monomer (a4) is represented by the above general formula (4).
X ⁴ in general formula (4) represents a group represented by -O- or -NH-.
R ⁷ represents a hydrogen atom or a methyl group, each R ⁸ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of 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 =3 represents a 6-membered ring.
Specific examples of the monomer (a4) include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate and the like.
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. is.

The monomer (a5) is represented by the above general formula (5).
X ⁵ in general formula (5) represents a group represented by -O- or -NH-.
R ⁹ represents a hydrogen atom or a methyl group, each R ¹⁰ independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a plurality of R ¹⁰ may be the same or different. r is an integer of 1 to 3, s is an integer of 0 to 1, and s=0 represents a 5-membered ring including dioxo, and s=1 represents a 6-membered ring.
Specific examples of the monomer (a5) include (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (meth)acrylic acid (5-ethyl-1,3 -dioxan-5-yl)methyl and the like.
Incidentally, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "MEDOL-10"), acrylic acid (5-ethyl-1,3 -dioxan-5-yl) methyl (manufactured by Tokyo Chemical Industry Co., Ltd.), (5-ethyl-1,3-dioxan-5-yl) methyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "Viscoat # 200 ”) are commercially 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 general formula (6), and R ¹³ in the general formula (6) has 1 to 1 carbon atoms. 20 alkyl group, 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 includes methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group and 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 , n-nonadecyl group and n-eicosyl group, branched alkyl groups such as isopropyl group, isobutyl group, 2-ethylhexyl group, isononyl group and isodecyl group.
Examples of the alkyl group having 1 to 20 carbon atoms in R ¹⁴ include those having 1 to 20 carbon atoms among the above alkyl groups having 1 to 20 carbon atoms.
R ¹³ is preferably an alkyl group having 1 to 15 carbon atoms from the viewpoint of oil film forming ability, wear properties, low temperature viscosity properties and friction reducing effect.
R ¹⁴ is preferably an alkyl group having 7 to 20 carbon atoms from the viewpoint of oil film forming ability, wear properties, low temperature viscosity properties and friction reducing effect.
The total number of carbon atoms of R ¹³ and R ¹⁴ is preferably 8 to 32, more preferably 20 to 24, from the viewpoints of oil film forming properties, wear properties, low temperature viscosity properties and friction reducing effect.
In the copolymer (A), as the monomer (b), one type may be used alone, 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 ratio 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 1-90% by weight, more preferably 1-70% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (a) is the same as the monomer (a) and the monomer from the viewpoint of oil film formation ability, wear properties and low temperature viscosity properties. 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 same as the monomer (a) and the monomer from the viewpoint of the 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 ratio 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 10-99% by weight, more preferably 30-99% by weight.
Among the constituent monomers of the copolymer (A), the content of the monomer (b) is the same as the monomer (a) and the monomer from the viewpoint of oil film forming ability, wear properties and low temperature viscosity properties. Based on the total weight of (b), it is preferably 60-99% by weight, more preferably 75-99% 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 properties, friction reducing effect, and solubility of (A) in the base oil. , preferably 10 to 90% by weight, more preferably 30 to 70% by weight, based on the total weight of the monomers (a) and (b).

The copolymer (A) of the present invention has, in addition to the monomers (a) and (b), an alkyl group having 1 to 4 carbon atoms (meta ) may contain an acrylic acid alkyl ester (d).
The alkyl group having 1 to 4 carbon atoms in the (meth)acrylic acid alkyl ester (d) includes linear alkyl groups such as methyl group, ethyl group, n-propyl group and n-butyl group, isopropyl group and isobutyl group. and branched alkyl groups such as t-butyl group.
The (meth)acrylic acid alkyl ester (d) is preferably methyl (meth)acrylate 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.
Among 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 pyrolysis gas chromatography.

The weight average molecular weight (hereinafter sometimes abbreviated as Mw) of the copolymer (A) is preferably 1,000 to 500,000 from the viewpoint of friction reduction effect, low-temperature viscosity characteristics and shear stability, More preferably 1,000 to 100,000, still more preferably 1,000 to 50,000, and most preferably 1,000 to 25,000. When the Mw of (A) is 1,000 or more, the friction reducing effect tends to be good, and when it is 500,000 or less, the shear stability, low-temperature viscosity characteristics, and viscosity characteristics tend to be good.
Mw is based on gel permeation chromatography and is obtained in terms of polystyrene.
The conditions for measuring the Mw of the copolymer (A) are as follows.
Apparatus: "HLC-802A" [manufactured by Tosoh Corporation]
Column: 2 "TSK gel GMH6" [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C.
Sample solution: 0.25% by weight tetrahydrofuran solution Solution injection volume: 100 μl
Detection device: refractive index detector Reference material: 12 standard polystyrene (TSK standard POLYSTYRENE) (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 during polymerization, the monomer concentration (solvent concentration), the amount of the catalyst or the amount of the chain transfer agent, and the like.

The solubility parameter (hereinafter sometimes abbreviated as "SP value") of the copolymer (A) is 7.3 to 9.6 (cal/cm ³ ) ^{1/ 2} is preferred, and 8.8 to 9.5 (cal/cm ³ ) ^1/2 is more preferred.

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. 147-154).

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

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

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, from the viewpoint of handleability. %.

Base oils (I) include mineral oils (solvent-refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking isoparaffins, naphthenic oils, etc.), synthetic lubricating oils [hydrocarbon-based synthetic lubricating oils (poly-α-olefin synthetic lubricating oils, etc.) and ester synthetic lubricating oils, etc.] and mixtures thereof. Among these, mineral oils and ester-based synthetic lubricating oils are preferred, and mineral oils are more preferred.
The base oil (I) may be used alone or in combination of two or more.

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

The cloud point of the base oil (measured according to JIS-K2269) is preferably -5°C or lower, more preferably -15°C or lower. When the cloud point of the base oil is within this range, the low-temperature viscosity of the lubricating oil composition is favorable.

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 properties to the lubricating oil composition, and further has low-temperature viscosity properties and low-to-medium temperature (40 to 80 ° C.) friction reducing effects. 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 lubricating oil additive of the present invention.
The content of the copolymer (A) in the lubricating oil composition of the present invention, based on the weight of the lubricating oil composition, is preferably It is 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, particularly preferably 1 to 10% by weight.

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

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 from 3.0 (cal/cm ³ ) ^1/2 , more preferably from 0.8 to 1.6 (cal/cm ³ ) ^1/2 .
When two or more types of base oils (I) are used in combination, the SP value of the base oil as a mixture is calculated by calculating the arithmetic average based on the respective weight ratios.

The lubricating oil composition of the present invention includes gear oils (differential oils and industrial gear oils, etc.), transmission gear oils (MTF), transmission oils [ATF and belt-CVTF, etc.], traction oils (toroidal-CVTF, etc.), shock It is suitable for use in absorber oils, power steering oils, hydraulic oils (construction machine hydraulic oils, industrial hydraulic oils, etc.), engine oils, and the like. Among these, gear oil, MTF, transmission oil, traction oil and engine oil are preferred, differential oil, MTF, ATF, belt-CVTF and engine oil are more preferred, and MTF and ATF are particularly preferred. , belt-CVTF and engine oil.

The lubricating oil composition of the present invention further comprises viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors and pour point depressants. It may contain one or more additives selected from the group. Specific examples of additives include the following.
(1) Viscosity index improver:
C (hereafter abbreviated as C) 1-7 alkyl (meth)acrylate/C8-40 linear or branched alkyl (meth)acrylate copolymer, dispersed monomer (amine monomer etc.)/C1-7 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 (Meth)acrylate copolymer, comb polymer [C1-7 alkyl (meth)acrylate/C8-40 linear or branched alkyl (meth)acrylate/polyolefin macromonomer], ethylene/C1-18 alkyl (meth) acrylate copolymers, polyisobutylenes, polyalkylstyrenes, ethylene/propylene copolymers, styrene/maleic acid ester copolymers, styrene/isoprene hydrogenated copolymers, etc.;
(2) cleaning agents:
Basic, overbased or neutral metal salts [such as overbased or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzene sulfonates and alkylnaphthalene sulfonates, etc.)], salicylates, phenates, naphthenates , carbonates, phosphonates and mixtures thereof;
(3) Dispersant:
succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates and borates, etc.;
(4) Antioxidants:
hindered phenols and aromatic secondary amines;
(5) Oiliness improver:
Long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine and oleylamide, etc.), etc.;
(6) Friction and wear modifier:
molybdenum-based and zinc-based compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate, etc.);
(7) extreme pressure agent:
sulfur compounds (mono- or disulfides, sulfoxides and sulfur phosphide compounds), phosphide compounds and chlorine compounds (chlorinated paraffins, etc.);
(8) Defoamer:
Silicon oil, metallic soap, fatty acid ester and phosphate compound, etc.;
(9) Demulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphates (polyoxyethylene-containing nonionic surfactant phosphates, etc.), 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, polyalkylstyrene, polyvinyl acetate, and the like.

The total content of 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.

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, unless otherwise specified, % means % by weight, and part means part by weight.

Examples 1-9 and Comparative Examples 1-4
Mineral oil (I-1) ("Ultra S-2" manufactured by S-Oil Co., Ltd., kinematic viscosity at 100 ° C.: 2.3 mm ² /s, viscosity index: 103) 40 parts, 60 parts of a blend of various monomers (a) to (d) listed in Table 1, 2,2'-azobis(2,4-dimethylvaleronitrile)0. 5 parts by weight and 0.2 parts by weight of 2,2'-azobis(2-methylbutyronitrile) were charged, and after nitrogen replacement (gas phase oxygen concentration 100 ppm), the mixture was sealed and stirred at 76°C. and the polymerization reaction was carried out at the same temperature for 5 hours. After that, the temperature was further raised to 90° C. and aged for 1 hour. After heating to 120 ° C., under reduced pressure (0.027 to 0.040 MPa) at the same temperature, unreacted monomers are removed over 2 hours, and the lubricating oil additives (R-1) to ( R-9), and comparative lubricating oil additives (R'-1) through (R'-4) were prepared.

The following monomers were used for various monomers (a) to (d) listed 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): tetrahydrofuran Furyl methacrylate (a5-1): (5-ethyl-1,3-dioxan-5-yl) methyl acrylate ("Viscoat #200" manufactured by Osaka Organic Industry Co., Ltd.)
(b-1): R ¹³ in general formula (6) is a methyl group, R ¹⁴ is an aliphatic alcohol of a linear alkyl group having 8 to 10 carbon atoms, R ¹³ in general formula (6) is an ethyl group, and R ¹⁴ is a mixture of a linear alkyl group having 8 to 10 carbon atoms with an aliphatic alcohol [higher alcohol "NEODOL 23" from Shell Chemicals] and an ester of methacrylic acid)
(b-2): R ¹³ in general formula (6) is a methyl group, R ¹⁴ is an aliphatic alcohol of a linear alkyl group having 10 to 12 carbon atoms, R ¹³ in general formula (6) is an ethyl group, and R Ester of methacrylic acid (b-3): 2-dodecylhexadecyl methacrylate, a mixture of ¹⁴ with a linear alkyl group having 10 to 12 carbon atoms and an aliphatic alcohol [higher alcohol "NEODOL 45" from Shell Chemicals] (b-4): 2-tetradecyloctadecyl methacrylate (b-5): R ¹³ in general formula (6) is a straight-chain alkyl group with 10 carbon atoms, and R ¹⁴ is a straight-chain alkyl group with 12 carbon atoms. Ester of group alcohol [higher alcohol "ISOFOL 24" from Sasol] 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 comparative lubricating oil additives (R'-1) to obtained in Comparative Examples 1 to 4 (R′-4) is mineral oil (I-2) (manufactured by SK, “YUBASE3”, 100° C. kinematic viscosity 3.1 mm ² /s, viscosity index: 112), and 100° C. kinematic viscosity is 5.4 mm ² / s, lubricating oil compositions (V-1) to (V-9) of the present invention, lubricating oil compositions (V'-1) to (V'-4) for comparison Obtained.

The lubricating oil compositions (V-1) to (V-9) of the present invention made in Examples 10 to 18, and the comparative lubricating oil composition (V'-1) made in Comparative Examples 5 to 8 (V′-4) were measured and evaluated for (1) oil film forming ability, (2) wear characteristics, and (3) low-temperature viscosity characteristics by the following methods. Table 2 shows the results.

<Oil film forming ability>
The oil film thickness (nm) at a constant load and slip ratio was calculated by light interferometry using an EHD tester (manufactured by PCS Instruments), and the oil film formation ability of each lubricating oil composition was evaluated. .
The test conditions of the EHD tester are shown below.
Disc: EHD Silica Spacer Layer Disc
Ball: 3/4'' Plain 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 taken as the measurement result.

Based on the measured oil film thickness (nm), evaluation was made according to the following criteria.
◎: 6 nm or more ○: 4 to 6 nm
△: 2 to 4 nm
×: less than 2 nm

<Wear characteristics>
A high-frequency reciprocating motion rig test was performed under the following conditions, and wear characteristics were evaluated from the wear scar diameter.
High-Frequency-Reciprocating-Rig (HFRR; manufactured by PCS Instruments) was used as the apparatus, SUJ2 was used as the material of the test steel ball, the diameter of the test steel ball was 6 mm, and SUJ2 was used as the material of the test disk. The test was conducted under 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 scar diameter was measured.

The wear scar diameter was evaluated according to the following criteria.
◎: Wear scar diameter is 180 μm or less ○: Wear scar diameter is 180 to 200 μm
△: wear scar diameter 200 ~ 230μm
×: 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.

Brookfield viscosity (mPa·s) was evaluated according to the following criteria.
◎: 5000 mPa s or less ○: 5000 to 7000 mPa s
△: 7000 to 10000 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 have excellent film-forming ability and wear properties, and low-temperature viscosity properties is superior.
On the other hand, it can be seen that the lubricating oil composition of Comparative Example 5, which contains a copolymer that does not contain the monomer (a) as a constituent monomer, has poor oil film forming ability and wear properties. In addition, Example ¹¹ and monomer (b) were not used (monomer (b'-1) and/or (b'- 2) was used), Comparative Example 6 (using n-dodecyl methacrylate) was superior to Example 11 in both oil film formation ability and wear characteristics. know that it is inferior. In addition, Comparative Example 7 (using n-hexadecyl methacrylate), which uses a material having a carbon number longer than that of Comparative Example 6, has an oil film forming ability similar to that of Example 11 and is good, but wear characteristics is found to be extremely inferior. In addition, it can be seen that Comparative Example 8, in which different carbon numbers are used together, is inferior to Example 11 in oil film forming ability and wear characteristics. That is, when using the monomer (b') in which R ¹³ in the general formula (6) is a hydrogen atom instead of an alkyl group, it is possible to obtain a lubricating oil composition having excellent oil film forming ability and wear characteristics. is difficult. Furthermore, 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) ("YUBASE3" manufactured by SK, kinematic viscosity 3.1 mm ² /s at 100°C, viscosity index: 112) was added to a reaction vessel equipped with a stirrer, a heating and cooling device, a thermometer and a nitrogen inlet tube. ) 50 parts, 50 parts of blends of various monomers (a) to (d) listed in Table 3, 2,2′-azobis(2,4-dimethylvaleronitrile) 0.5 parts by weight and 2,2 0.2 parts by weight of '-azobis(2-methylbutyronitrile) was added, and after nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76 ° C. while stirring under a closed condition. for 5 hours. After that, the temperature was further raised to 90° C. and aged for 1 hour. After heating to 120 ° C., under reduced pressure (0.027 to 0.040 MPa) at the same temperature, unreacted monomers are removed over 2 hours, and the lubricating oil additives (R-10) to ( R-19), and comparative lubricating oil additives (R'-5) through (R'-7) were prepared.

Examples 29-38 and Comparative Examples 12-14
In a stainless steel container equipped with a stirrer, 10 parts by weight of an engine oil additive package (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, lubricating oil additives (R-10) to (R-19) obtained in Examples 10 to 19, and Comparative Examples 9 to The lubricating oil additives (R'-5) to (R'-7) for comparison obtained in 11 are respectively added so that the content of the copolymer (A) is 1% by weight, and further obtained lubrication Add a viscosity index improver (polyalkyl methacrylate, Mw 500,000, resin content 21% by weight) so that the 150° C. HTHS viscosity of the oil composition is 2.60±0.05 (mm ² /s) By mixing, lubricating oil compositions (V-10) to (V-19) of the present invention and comparative lubricating oil compositions (V'-5) to (V'-7) were obtained.

The lubricating oil compositions (V-10) to (V-19) of the present invention made in Examples 29 to 38, and the comparative lubricating oil composition (V'-5) made in Comparative Examples 12 to 14 (1) Oil film forming ability and (2) wear characteristics were measured and evaluated for (V'-7) by the above methods. In addition, (3) MTM friction coefficient was measured and evaluated by the following method. Table 4 shows the results.

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. Table 4 shows the results.
<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: 10mm/s to 3,000mm/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 coefficient of friction at speeds of 10 mm/s, 100 mm/s and 1,000 mm/s at each temperature was used as the measurement result.

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 have excellent film-forming ability and wear properties, and further have a friction-reducing effect. is superior.
On the other hand, it can be seen that the lubricating oil composition of Comparative Example 12, which contains a copolymer that does not contain the monomer (a) as a constituent monomer, has poor oil film forming ability and wear properties. In addition, Example ³³ and monomer (b) were not used (monomer (b'-1) and/or (b'- 2) was used), Comparative Example 13 (using n-dodecyl methacrylate) was superior to Example 33 in both oil film formation ability and wear characteristics. know that it is inferior. In addition, Comparative Example 14 (using n-hexadecyl methacrylate), which uses a material having a carbon number longer than that of Comparative Example 13, has a good oil film forming ability similar to that of Example 33, but wear characteristics is found to be inferior. That is, when using the monomer (b') in which R ¹³ in the general formula (6) is a hydrogen atom instead of an alkyl group, it is possible to obtain a lubricating oil composition having excellent oil film forming ability and wear characteristics. is difficult. Furthermore, it can be seen that Comparative Examples 13 and 14 are extremely inferior in friction reduction 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 low-to-medium temperature range (40 to 80 ° C.) friction reducing effect, so it is used as a drive system lubricating oil ( 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)

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 general formula (3′) One or more selected from the group consisting of a monomer (a3) represented by the following general formula (4), a monomer (a4) represented by the following general formula (4), and a monomer (a5) represented by the following general formula (5) A lubricating oil additive containing a monomer (a) having an alicyclic structure of and a copolymer (A) having a monomer (b) represented by the general formula (6) as an essential constituent monomer wherein the total weight ratio of the monomer (a) and the monomer (b) in the constituent monomers of the copolymer (A) is the sum of the constituent monomers of the copolymer (A) A lubricating oil additive that is at least 80% by weight on a weight basis .

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

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

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

[R ¹¹ represents a hydrogen atom or a methyl group, X ⁶ represents a group represented by —O 2 — , and R ¹² O represents an alkyleneoxy group having 2 to 4 carbon atoms. t is an integer of 0 , R ¹³ represents an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents an alkyl group having 8 to 20 carbon atoms. ] 2. The lubricating oil additive according to claim 1, wherein the copolymer (A) has a weight average molecular weight of 1,000 to 500,000. 3. The lubricating oil additive according to claim 1, further comprising base oil (I). A lubricating oil composition containing the lubricating oil additive according to any one of claims 1 to 3. Furthermore, one or more additives selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors and pour point depressants. 5. The lubricating oil composition according to claim 4, comprising an agent.