JP5032029B2 - Viscosity index improver and lubricating oil composition - Google Patents

Description

  The present invention relates to lubricating oil additives. Specifically, the present invention relates to a viscosity index improver comprising a nitrogen-containing poly (meth) acrylate polymer and a lubricating oil composition containing the same.

In recent years, the need for low-viscosity lubricants is increasing from the viewpoint of fuel efficiency of automobiles. However, simply lowering the viscosity deteriorates the lubricity at high temperatures and leads to troubles such as wear. Therefore, the addition of a viscosity index improver is effective as a means for maintaining a high viscosity at a high temperature and reducing the viscosity at a low temperature, and has been widely used in the past (see Patent Document 1).
However, conventional viscosity index improvers are insufficient to further reduce the viscosity, and improvements have been demanded.
JP-A-9-3131

  An object of the present invention is to provide a viscosity index improver having a viscosity index improving effect and abrasion resistance required when the viscosity is lowered.

As a result of intensive studies, the present inventors have found a viscosity index improver having a viscosity index improving ability and wear resistance, and have reached the present invention. That is, the present invention
(Meth) acrylic acid alkyl ester (a 4 ) having 19 to 36 carbon atoms in the alkyl group (branched) and aminoalkyl (2 to 6 carbon atoms) (meth) acrylate, alkyl (1 to 6 carbon atoms) aminoalkyl ( Essential constituent monomer of carbon number 2 to 6) (meth) acrylate, dialkyl (carbon number 1 to 4) aminoalkyl (carbon number 2 to 6) (meth) acrylate, or morpholinoethyl (meth) acrylate (b 2 ) And a viscosity index improver comprising a polymer (A) in which the proportion of (a 4 ) is 10 to 80% by weight and the proportion of (b 2 ) is 20 to 90% by weight based on the total mass of monomers; A viscosity index improver composition comprising the viscosity index improver and a diluent and / or additive; a lubricating oil composition comprising the viscosity index improver or viscosity index improver composition and a base oil; And a lubricating oil composition containing 0.5 to 30% by weight of the viscosity index improver based on the weight of the lubricating oil composition.

  The viscosity index improver of the present invention has a new wear prevention function in addition to the effect of improving the viscosity index which is the function of the conventional viscosity index improver.

  The polymer (A), which is an essential component of the viscosity index improver composition of the present invention, contains at least one of alkyl group (meth) acrylic acid alkyl ester (a) having 1 to 36 carbon atoms as an essential component. It is a polymer used as a polymer, and examples of (a) include the following (a1) to (a4).

(A1) (meth) acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group:
Methyl (meth) acrylate (of which methyl methacrylate is hereinafter abbreviated as MMA), ethyl (meth) acrylate, n- or (meth) acrylate, iso (propyl), (meth) acrylate n-, iso -Or sec-butyl.

(A2) (Meth) acrylic acid alkyl ester having 8 to 15 carbon atoms in the alkyl group (straight and / or branched):
N-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, n-isodecyl (meth) acrylate, n-undecyl (meth) acrylate, (meth) acrylic acid n-dodecyl, 2-methylundecyl (meth) acrylate, n-tridecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, n-tetradecyl (meth) acrylate, 2- (meth) acrylate 2- Methyltridecyl, n-pentadecyl (meth) acrylate, 2-methyltetradecyl (meth) acrylate, alcohol produced by oxo synthesis [for example, trade name “Dovanol 23” (Mitsubishi Chemical), “Neodol 23” (Shell Chemistry), “Tridecanol” (manufactured by Kyowa Hakko), “Oxocol 1213” (manufactured by Nissan Chemical), “Dobano” (Meth) acrylic acid ester with “Nole 45” (Mitsubishi Chemical), “Neodol 45” (Shell Chemical), “Oxocol 1415” (Nissan Chemical), etc. The acid ester is D23, and the methacrylic acid ester with “Neodol 45” is abbreviated as D45).
Among (a2), preferred is a (meth) acrylic acid alkyl ester having a linear and / or branched alkyl group having 12 to 15 carbon atoms.

(A3) Alkyl group (meth) acrylic acid alkyl ester having 16 to 36 (straight chain) alkyl groups and (meth) acrylic acid alkyl ester having 16 to 18 (branched) alkyl groups:
N-hexadecyl acrylate, n-hexadecyl methacrylate (hereinafter abbreviated as HMA), n-octadecyl acrylate, n-octadecyl methacrylate (hereinafter abbreviated as OMA), n-eicosyl (meth) acrylate, (meth) acrylic acid n-docosyl, 2-methylpentadecyl (meth) acrylate, 2-hexyldecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, 2-octyldecyl (meth) acrylate, (meth) acryl Examples include acid 2-hexyldecyl and 2-methylheptadecyl (meth) acrylate. Among (a3), a (meth) acrylic acid alkyl ester having a linear alkyl group having 16 to 18 carbon atoms is preferred.
(A4) (meth) acrylic acid alkyl ester having 19 to 36 (branched) carbon atoms in the alkyl group:
Examples include (meth) acrylic acid 2-methyloctadecyl group, (meth) acrylic acid 2-octyldodecyl group, acrylic acid 2-decyltetradecyl group, methacrylate 2-decyltetradecyl group (hereinafter abbreviated as DOM), and the like. Among (a4), 2-octyldodecyl (meth) acrylate and 2-decyltetradecyl (meth) acrylate are preferred.

(A5) Alkyl (meth) acrylic acid alkyl ester having 5 to 7 carbon atoms (linear and / or branched):
(Meth) acrylic acid n-, iso-, sec- and neopentyl, hexyl (meth) acrylate, heptyl (meth) acrylate, and the like.

Among (a), (a2) to (a4) and combinations of two or more of these are preferable.

  The polymer (A) is a polymer having at least one of the nitrogen atom-containing monomers (b) as an essential constituent monomer, and (b) includes the following (b1) to (b5): Can be mentioned.

(B) a nitrogen atom-containing monomer;

(B1) Nitro group-containing monomer:
For example, 4-nitrostyrene
(B2) A primary to tertiary amino group-containing vinyl monomer:
Primary amino group-containing vinyl monomers such as alkenylamines having 3 to 6 carbon atoms [(meth) allylamine, crotylamine etc.] and aminoalkyl (2 to 6 carbon atoms) (meth) acrylate [aminoethyl (meth) acrylate Etc.]; secondary amino group-containing vinyl monomer, for example, alkyl (C1-6) aminoalkyl (C2-6) (meth) acrylate [t-butylaminoethyl methacrylate, methylaminoethyl (meth) Acrylate etc.], diphenylamine (meth) acrylamide [4-diphenylamine (meth) acrylamide, 2-diphenylamine (meth) acrylamide etc.] and C6-C12 dialkenylamine [di (meth) allylamine etc.]; tertiary amino group Containing vinyl monomers, eg dialkyl (carbon 1-4) aminoalkyl (2-6 carbon atoms) (meth) acrylate [dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.], dialkyl (1-4 carbon atoms) aminoalkyl (2 carbon atoms) 6) (Meth) acrylamide [dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, etc.], tertiary amino group-containing aromatic vinyl monomer [N, N-dimethyl Aminostyrene, etc.] and nitrogen-containing heterocyclic ring-containing vinyl monomers [morpholinoethyl (meth) acrylate, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc. ];
(B3) Quaternary ammonium base-containing vinyl monomer:
For example, the above-mentioned tertiary amino group-containing vinyl monomer is quaternized with a quaternizing agent (alkyl chloride having 1 to 12 carbon atoms, dialkyl sulfuric acid, dialkyl carbonate, benzyl chloride, etc.). Can be mentioned. Specifically, examples of the alkyl (meth) acrylate quaternary ammonium salt include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyltriethylammonium chloride, and (meth) acryloyloxyethyldimethylbenzylammonium. Chloride, (meth) acryloyloxyethylmethylmorpholino ammonium chloride and the like; alkyl (meth) acrylamide quaternary ammonium salts include, for example, (meth) acryloylaminoethyltrimethylammonium chloride, (meth) acryloylaminoethyltriethylammonium chloride, (Meth) acryloylaminoethyldimethylbenzylammonium chloride, etc .; other quaternary ammonium salts The containing vinyl monomers, for example, dimethyl diallyl ammonium methyl sulfate, etc. trimethyl vinylphenyl ammonium chloride, and the like.
(B4) Amphoteric vinyl monomer:
N- (meth) acryloyloxy (or amino) alkyl (C1-10) N, N-dialkyl (C1-5) ammonium-N-alkyl (C1-5) carboxylate (or sulfate), For example, N- (meth) acryloyloxyethyl N, N-dimethylammonium N-methylcarboxylate, N- (meth) acryloylaminopropyl N, N-dimethylammonium N-methylcarboxylate, and N- (meth) acryloyloxy And ethyl N, N-dimethylammonium propyl sulfate.
(B5) Nitrile group-containing monomer:
Examples include (meth) acrylonitrile. ,

Among (b), (b2) to (b4) and a combination of two or more of these are preferable.
Of these, (b2) to (b4) are preferably (b2), more preferably a secondary amino group-containing vinyl monomer and a tertiary amino group-containing vinyl monomer, particularly preferably dimethylaminoethyl acrylate, Dimethylaminoethyl methacrylate (hereinafter abbreviated as DAE), diethylaminoethyl (meth) acrylate, morpholinoethyl acrylate and morpholinoethyl methacrylate (hereinafter abbreviated as MEM).

Examples of the monomer (c) other than (a) and (b) that can be used as the constituent monomer of (A) include the following (c1) to (c10).

(C1) Aliphatic hydrocarbon vinyl monomer:
For example, alkenes having 2 to 20 carbon atoms [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.] and alkadienes having 4 to 12 carbon atoms [butadiene, isoprene, 1,4- Pentadiene, 1,6-heptadiene, 1,7-octadiene, etc.]

(C2) Alicyclic hydrocarbon vinyl monomer:
For example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, and ethylidenebicycloheptene, etc.

(C3) Aromatic hydrocarbon vinyl monomer:
For example, styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4 -Crotylbenzene, 2-vinylnaphthalene, etc.

(C4) Vinyl esters, vinyl ethers, vinyl ketones:
For example, vinyl esters of saturated fatty acids having 2 to 12 carbon atoms [vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octoate, etc.], alkyl ethers having 1 to 12 carbon atoms, aryl or alkoxyalkyl vinyl ethers [methyl vinyl ether, ethyl vinyl ether , Propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl 2-methoxyethyl ether, vinyl 2-butoxyethyl ether, etc.], and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms [methyl vinyl ketone, ethyl vinyl] Ketone, phenyl vinyl ketone, etc.],

(C5) an epoxy group-containing vinyl monomer;
For example, glycidyl (meth) acrylate glycidyl (meth) allyl ether, etc.

(C6) a halogen element-containing vinyl monomer;
For example, vinyl chloride, vinyl bromide, vinylidene chloride, (meth) allyl chloride, halogenated styrene (dichlorostyrene, etc.)

(C7) an ester of an unsaturated polycarboxylic acid;
Examples thereof include alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids, and among them, alkyl diesters having 1 to 8 carbon atoms of unsaturated dicarboxylic acids [maleic acid, fumaric acid, itaconic acid, etc.] [dimethyl maleate, Dimethyl fumarate, diethyl maleate, dioctyl maleate]

(C8) hydroxyl group-containing vinyl monomer;
For example, hydroxyl group-containing aromatic vinyl monomer [p-hydroxystyrene etc.], hydroxyalkyl (2 to 6 carbon atoms) (meth) acrylate [2-hydroxyethyl (meth) acrylate, 2 or 3-hydroxypropyl (meta) ) Acrylates, etc.], mono- or di-hydroxyalkyl (1 to 4 carbon atoms) substituted (meth) acrylamide [N, N-dihydroxymethyl (meth) acrylamide, N, N-dihydroxypropyl (meth) acrylamide, N, N -Di-2-hydroxybutyl (meth) acrylamide etc.], vinyl alcohol (formed by hydrolysis of vinyl acetate unit), C3-C12 alkenol [(meth) allyl alcohol, crotyl alcohol, isocrotyl Alcohol, 1-octenol, 1-undece Etc.], C 4-12 alkene diol [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol etc.], hydroxyalkyl (C 1-6 ) Alkenyl (3 to 10 carbon atoms) ether [2-hydroxyethylpropenyl ether and the like], polyhydric (3 to 8 valent) alcohol (alkane polyol, intramolecular or intermolecular dehydrated product, saccharide such as glycerin, pentaerythritol, Alkitol (3 to 10 carbon atoms) ether or (meth) acrylate [sucrose (meth) allyl ether] of sorbitol, sorbitan, diglycerin, sucrose,

(C9) a polyoxyalkylene chain-containing vinyl monomer;
For example, polyoxyalkylene glycol (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 50), or polyoxyalkylene polyol [polyoxyalkylene ether of 3 to 8 valent alcohol (alkyl group having 2 to 4 carbon atoms) , Degree of polymerization 2-100)], or mono (meth) acrylates thereof (polyethylene glycol (molecular weight 100-300) mono (meth) acrylate, polypropylene glycol (molecular weight 130-500) Mono (meth) acrylate, methoxypolyethylene glycol (molecular weight 110-310) (meth) acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth) acrylate, mono (meth) acrylic acid polyoxyethylene (molecular weight 150-230 Sorbitan], etc.,

(C10) carboxyl group-containing vinyl monomer;
Monocarboxyl group-containing vinyl monomers such as unsaturated monocarboxylic acids [(meth) acrylic acid, α-methyl (meth) acrylic acid, crotonic acid, cinnamic acid, etc.], monoalkyls of unsaturated dicarboxylic acids (carbon number) 1-8) Esters [maleic acid monoalkyl esters, fumaric acid monoalkyl esters, itaconic acid monoalkyl esters, etc.]; vinyl monomers containing two or more carboxyl groups, such as maleic acid, fumaric acid, itaconic acid Citraconic acid and the like.

  Among these monomers (c1) to (c10), preferred are (c2), (c8) and a combination thereof.

  The proportion of (a) in the monomer constituting (A) is, from the viewpoint of solubility, the lower limit is usually 10% (hereinafter, unless otherwise specified,% is% by weight), preferably 20%, particularly The upper limit is preferably 30%, and the upper limit is usually 80%, preferably 75%.

The proportion of (b) in the monomer constituting (A) is, in terms of viscosity index improving ability and wear resistance, the lower limit is usually 20%, preferably 25%, and the upper limit is usually 90%, preferably Is 80%, particularly preferably 70%.
The proportion of (c) in the monomer constituting (A) is usually 20% or less, preferably 0% or 15% or less, from the viewpoints of viscosity index improving ability and wear resistance.

  The weight average molecular weight of the polymer (A) is preferably 1,000 to 500,000, more preferably 1,000 to 200,000, from the viewpoints of viscosity index improving ability and wear resistance.

  The rate of decrease in kinematic viscosity according to the shear stability test at 100 ° C. of the polymer (A) is preferably 0 to 10%, more preferably 0 to 8%, particularly preferably 0 to 5%, particularly preferably. It is preferable that it is 0 to 2%. The rate of decrease in kinematic viscosity according to the shear breaking stability test in the present invention is determined by the following method.

[Method of measuring rate of decrease in kinematic viscosity by shear stability test]
A polymer is dissolved in mineral oil (100 ° C. kinematic viscosity = 2.94 mm ² / s, 40 ° C. kinematic viscosity = 11.25 mm ² / s, viscosity index = 114), and the solution has a 100 ° C. kinematic viscosity of 6.0. The amount of the polymer added is adjusted so as to be ± 0.1 mm ² / s to obtain a mineral oil solution of the polymer.
About this solution, according to JASO M347-95, the decreasing rate of 100 degreeC kinematic viscosity is calculated | required.

  (A) can be obtained by a known production method. For example, the monomer can be obtained by radical polymerization in the presence of a polymerization catalyst using a diluent as required.

Diluents include aliphatic solvents [aliphatic hydrocarbons having 6 to 18 carbon atoms (hexane, heptane, cyclohexane, octane, decalin, kerosene, etc.)]; aromatic solvents {aromatic solvents having 7 to 15 carbon atoms [toluene] , Xylene, ethylbenzene, aromatic mixed solvent having 9 carbon atoms (mixture of trimethylbenzene, ethyltoluene, etc.), aromatic mixed solvent having 10 to 11 carbon atoms, etc.], mineral oil [for example, solvent refined oil, paraffin oil, isoparaffin And / or hydrocracking high viscosity index oils, naphthenic oils], synthetic lubricating oils [hydrocarbon-compatible lubricating oils (poly-α-olefin based synthetic lubricating oils), ester based synthetic lubricating oils], etc. Of these, mineral oil is preferred.
Although the diluent may be removed after polymerization by a method such as distilling off under reduced pressure, the method of leaving the diluent as it is is preferable from the viewpoint of handleability.
Examples of the polymerization catalyst include azo catalysts (for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile) (hereinafter abbreviated as AMBN), 2,2′-azobis. (2,4-dimethylvaleronitrile) (hereinafter abbreviated as ADVN), dimethyl 2,2-azobisisobutyrate, etc.) and peroxides (for example, t-butyl peroxypivalate, t-hexyl peroxypi Valate, t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-amyl peroxy 2- Ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, dibutylperoxytrimethyladipate, Emissions benzoyl peroxide, cumyl peroxide, lauryl peroxide, benzoyl peroxide, cumyl peroxide, lauryl peroxide) can be used.
Furthermore, if necessary, a chain transfer agent may be used in combination. Examples of such compounds include thiols (n-lauryl mercaptan (hereinafter abbreviated as DM), mercaptoethanol, mercaptopropanol, etc.), thiolic acids (thioglycolic acid). , Thiomalic acid, etc.), amines (dibutylamine, etc.) and the like. The amount of the chain transfer agent is preferably 0.001 to 5%, more preferably 0.05 with respect to the mass of the monomer. ~ 3%. The reaction temperature is 50 to 140 ° C, preferably 70 to 120 ° C. In addition to solution polymerization using the above diluent, it can also be obtained by bulk polymerization, emulsion polymerization or suspension polymerization. Further, the polymerization mode when (A) is a copolymer may be any of random copolymerization, alternating copolymerization or block copolymerization, and (A) may be either linear or branched.
Means for adjusting the shear stability of the polymer depending on the polymerization conditions include, for example, adjusting the temperature during polymerization, the monomer concentration (diluent concentration), the catalyst amount, the chain transfer agent amount, and the like.
From the viewpoint of the polymerization rate, the oxygen concentration in the gas phase is preferably 10 to 5,000 ppm, more preferably 100 to 2,000 ppm, and particularly preferably 100 to 1,000 ppm.

The viscosity index improver of the present invention usually comprises only the polymer (A).
The viscosity index improver composition of the present invention comprises a viscosity index improver comprising (A), and a diluent and / or an additive (additive other than a diluent).
As the diluent, the diluent used in the production of the above-mentioned (A) may be left as it is or may be newly added. When newly added, the diluent may have the same composition as the remaining diluent or a different composition.
The content of the diluent is not particularly limited, but the lower limit is preferably 10%, more preferably 30%, particularly preferably 40% based on the mass of (A), and the upper limit is the mass of (A). Is preferably 900%, more preferably 800%, particularly preferably 600%.
A higher ratio of diluent is preferred in that it dissolves easily in the base oil, but too much is not economical.

Production of the viscosity index improver composition of the present invention,
(1) A method in which a monomer is polymerized in the presence of a diluent or, if necessary, further diluted with a diluent.
(2) A method of diluting with a diluent later without using a diluent during polymerization.
Etc. The method (1) is preferable from the viewpoint of handling.

  Additives that can be contained in the viscosity index improver composition of the present invention include pour point depressants (for example, polymethacrylate pour point depressants, alkylnaphthalenes, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, α-olefin copolymer, alkenyl succinic acid amide, etc.), detergent (sulfonate-type, salicylate-type, phenate-type, naphthenate-type Ca and Mg salts, calcium carbonate), dispersant (succinimide type; bistype, Monotype, borate type, Mannich condensate, etc.), antioxidant (zinc dithiophosphate, amine, diphenylamine, hindered phenol, zinc thiophosphate, trialkylphenol, etc.), oil improver (long chain fatty acid; Oleic acid, long chain fatty acid ester; oleic acid ester, Chain amine type: oleylamine, etc., long chain amide; oleamide), low molecular type friction and wear modifier (molybdenum dithiophosphate, molybdenum carbamate, zinc dialkyldithiophosphate, etc.), low molecular type extreme pressure agent (sulfur phosphorus type, sulfur type) , Phosphorus-based, chlor-based, etc.), antifoaming agents (silicone oil, metal soap, fatty acid ester, phosphate ester, etc.), demulsifier (quaternary ammonium salt, sulfated oil, phosphate ester), and corrosion inhibitor ( Nitrogen compounds such as benzotriazole, sulfur and nitrogen-containing compounds such as 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate) and the like.

Among the additives, a pour point depressant is preferable from the viewpoint that the effect of the viscosity index improver of the present invention is easily exhibited.
Among the pour point depressants, preferred are polymethacrylate pour point depressants (hereinafter abbreviated as PMA pour point depressants), and particularly preferred is the number of carbon atoms in which at least one of the monomers is an alkyl group. Is a PMA pour point depressant containing 12-18 alkyl (meth) acrylates and having an average carbon number of 12-16.
Specifically, dodecyl methacrylate / hexadecyl methacrylate (10-50% / 50-90%) copolymer [average carbon number: 14.0-15.6], dodecyl methacrylate / tetradecyl methacrylate (90- 70% / 10-30%) copolymer [average carbon number: 12.2-12.6], and D23 / HMA / OMA (30-70% / 5-50% / 3-20%) copolymer [Average carbon number: 13.7 to 15.4].
In the viscosity index improver composition of the present invention, a preferred ratio of (A) / PMA pour point depressant is (99 to 85) / (1 to 15) from the viewpoint of low temperature viscosity.

The content of the additive based on the weight of the viscosity index improver composition is 0-20% for the pour point depressant, preferably 0.1-10%, more preferably 0.1-5%, and 0 for the detergent. ~ 30%, preferably 0.1-20%, dispersant 0-30%, preferably 0.2-20%, antioxidant 0-10%, preferably 0.1-2%, oiliness improver 0 to 5%, preferably 0.1 to 2%, low molecular type frictional wear modifier is 0 to 5%, preferably 0.1 to 3%, low molecular type extreme pressure agent is 0 to 40%, preferably 0.00. 1 to 10%, antifoaming agent is 2 to 1,000 ppm, preferably 10 to 700 ppm, demulsifier is 0 to 3%, preferably 0 to 1%, corrosion inhibitor is 0 to 3%, preferably 0 to 2% %.
The total content of additives based on the weight of the viscosity index improver composition is usually 0 to 50%, preferably 0 to 30%, more preferably 0 to 20%.

  The ratio of (A) / diluent / additive in the viscosity index improver composition of the present invention is usually 30 to 90/10 to 70/0 to 50, preferably 40 to 80/20 to 60/0 to 30, More preferably, it is 50-80 / 20-50 / 0-20.

The lubricating oil composition of the present invention contains a base oil and either the above viscosity index improver or the above viscosity index improver composition.
The base oil is not particularly limited. For example, solvent refined oil, high viscosity index oil containing isoparaffin and / or hydrocracking, hydrocarbon-based synthetic lubricating oil (poly-α-olefin-based synthetic lubricating oil), ester-based synthetic lubricating Oil, naphthenic oil, alkylaphthalene and the like. Among these, preferred are high viscosity index oils containing isoparaffins and / or hydrocracking, hydrocarbon-based synthetic lubricating oils (poly-α-olefin-based synthetic lubricating oils), and ester-based synthetic lubricating oils.
Also, of the base oil, kinematic viscosity at 100 ° C. is 1 to 15 mm ² / s, preferably 2 to 5 mm ² / s, the viscosity index of usually 80 or more, preferably 100 or more, more preferably 105 to 180 A base oil is preferred. A lubricating oil composition containing such a base oil has a higher viscosity index and good fuel economy.

  Further, the cloud point (JIS K2269-1993) of the base oil is preferably −5 ° C. or lower. More preferably, it is −15 ° C. to −60 ° C. When the cloud point of the base oil is within this range, the low temperature viscosity of the lubricating oil composition obtained with a small amount of wax precipitation is good.

  The lubricating oil composition of the present invention preferably contains 0.5 to 30% as (A) or a viscosity index improver based on the mass of the base oil.

When the lubricating oil composition is engine oil, 0.5 to 15% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 3 to 10 mm ² / s. .
In the case of gear oil, 3 to 30% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 3 to 10 mm ² / s.
In the case of automatic transmission oil (ATF, belt CVT oil), it is preferable to add 2 to 25% as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s. .
In the case of traction oil, 0.5 to 15% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 1 to 5 mm ² / s.
In the case of hydraulic oil, 0.5 to 25% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 1 to 10 mm ² / s.

  Lubricating oil compositions to which the viscosity index improver composition of the present invention is added include engine oil for transportation equipment, various machine tools, industrial gear oil, automotive gear oil (MT oil, differential oil, etc.), automatic transmission. Used for machine oil (ATF, CVT oil), traction oil, shock absorber oil, power steering oil, industrial hydraulic oil, etc. Among these, from the viewpoint of viscosity index and wear resistance, it is preferably used for gear oil.

The lubricating oil composition to which the viscosity index improver of the present invention is added has a kinematic viscosity at 3O <0> C of 3 to 20 mm < ² > / s.
The thickness is preferably 4 to 10 mm ² / s, particularly preferably 4.5 to 7 mm ² / s.

<Example>
The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In addition, the part in an Example and a comparative example represents a weight part.

Production Examples 1 to 5;
Into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, a dropping funnel, and a nitrogen blowing tube, 25 parts of toluene as a diluent was charged, and the monomers listed in Table 1 were placed in another glass beaker. 100 parts in total, dodecyl mercaptan (abbreviated as DM) as the chain transfer agent in the amount described in Table 1, and 2,2′-azobis (abbreviated as 2,4-dimethylvaleronitrile: ADVN) and / or radical polymerization initiator Alternatively, 2,2′-azobis (2-methylbutyronitrile: abbreviated as AMBN) was charged in the amount shown in Table 1, stirred and mixed at 20 ° C. to prepare a monomer solution, and charged into a dropping funnel. The gas phase portion of the reaction vessel was replaced with nitrogen, and the gas phase oxygen concentration was adjusted to 500 to 1,000 ppm. The monomer solution was added dropwise at 85 ° C. for 4 hours in a sealed state, and after aging at 85 ° C. for 2 hours from the end of dropping, the low-boiling components were retained for 2 hours at 130 ° C. for 3 hours and a reduced pressure of 4 kPa or less. The polymers (A-1) to (A-3) and comparative polymers (X-1) and (X-2) were obtained.

Evaluation Examples 1 to 3, Comparative Evaluation Examples 1 and 2;
Table 1 shows the results of the rate of decrease in kinematic viscosity measured by the method described above for the polymers (A-1) to (A-3) and the comparative polymers (X-1) and (X-2). Show.

Examples 1-3, Comparative Examples 1 and 2;
Polymers (A-1) to (A-3), comparative polymers (X-1), (X-2) and diluent (mineral oil D: kinematic viscosity at 100 ° C. is 2.3 mm ² / s, Viscosity index 83) was stirred and mixed at 100 ° C. for 2 hours in parts by weight shown in Table 2, and each of them was mixed with viscosity index improver compositions (CA-1) to (CA-3) and comparative viscosity index improver compositions ( CX-1) and (CX-2).

Examples 4-6 and Comparative Examples 3 and 4
Viscosity index improver compositions (CA-1) to (CA-3) and comparative viscosity index improver compositions (CX-1) and (CX-2) are added in the amounts shown in Table 3, and base oil (mineral) Oil E: The kinematic viscosity at 100 ° C. was stirred and dissolved until it became uniform at 4.3 mm ² / s, viscosity index 121), and the lubricating oil compositions of Examples 4 to 6 and Comparative Examples 3 and 4 were obtained. Table 3 shows the results of measuring the kinematic viscosity at 100 ° C. (JIS K2283), the viscosity index (JIS K2283) and the wear resistance (wear scar diameter) of these lubricating oil compositions.

[Measurement method of wear resistance]
Using SRV, the wear scar diameter of the ball is measured with a ball-on-disk.
Wear scar length: Average value of vertical and horizontal diameters of ball wear scar Equipment: Optimol SRV testing machine (Nihon Parkerizing Co., Ltd.)
Ball: 10mm in diameter
Disc: Diameter 24mm x Thickness 7.9mm
Load: 200N
Stroke width: 2mm
Frequency: 50Hz
Test time: 10 minutes

  Since the lubricating oil composition using the viscosity index improver of the present invention can be made lower in viscosity than a lubricating oil composition using a conventional PMA viscosity index improver, it meets the demand for fuel economy of automobiles. I can do it. Therefore, drive system lubricating oil (manual transmission oil, differential gear oil, automatic transmission oil, belt CVT oil, etc.), hydraulic oil (machine hydraulic oil, power steering oil, shock absorber oil, etc.), engine oil (for gasoline, diesel) For example), traction oil and the like.

Claims (7)

(Meth) acrylic acid alkyl ester (a 4 ) having 19 to 36 carbon atoms in the alkyl group (branched) and aminoalkyl (2 to 6 carbon atoms) (meth) acrylate, alkyl (1 to 6 carbon atoms) aminoalkyl ( Essential constituent monomer of carbon number 2 to 6) (meth) acrylate, dialkyl (carbon number 1 to 4) aminoalkyl (carbon number 2 to 6) (meth) acrylate, or morpholinoethyl (meth) acrylate (b 2 ) And a viscosity index improver comprising a polymer (A) having a ratio of (a 4 ) of 10 to 80% by weight and a ratio of (b 2 ) of 20 to 90% by weight based on the total mass of the monomers. Polymer (A) is, according to claim 1 Symbol placement ratio of a following based on the total weight of the monomer (c1) ~ (c10) monomer (c) is a polymer 20 wt% or less Viscosity index improver.
(C1) Aliphatic hydrocarbon vinyl monomer
(C2) Alicyclic hydrocarbon vinyl monomer
(C3) Aromatic hydrocarbon vinyl monomer
(C4) Vinyl esters, vinyl ethers, vinyl ketones
(C5) Epoxy group-containing vinyl monomer
(C6) Halogen element-containing vinyl monomer
(C7) Unsaturated polycarboxylic acid ester
(C8) Hydroxyl group-containing vinyl monomer
(C9) Polyoxyalkylene chain-containing vinyl monomer
(C10) Carboxyl group-containing vinyl monomer The viscosity index improver according to claim 1 or 2 , wherein the rate of decrease in kinematic viscosity at 100 ° C by the shear stability test specified below for the polymer (A) is 0 to 10%.
[Method of measuring rate of decrease in kinematic viscosity by shear stability test]
A polymer is dissolved in mineral oil (100 ° C. kinematic viscosity = 2.94 mm ² / s, 40 ° C. kinematic viscosity = 11.25 mm ² / s, viscosity index = 114), and the solution has a 100 ° C. kinematic viscosity of 6.0. The amount of the polymer added is adjusted so as to be ± 0.1 mm ² / s to obtain a mineral oil solution of the polymer.
About this solution, according to JASO M347-95, the decreasing rate of 100 degreeC kinematic viscosity is calculated | required. A viscosity index improver composition comprising the viscosity index improver according to any one of claims 1 to 3 , and a diluent and / or an additive. Claim 1 and a viscosity index improver or viscosity index improver composition according to any of 4, the lubricating oil composition comprising a base oil. A lubricating oil composition comprising the viscosity index improver according to any one of claims 1 to 3 in an amount of 0.5 to 30% by weight based on the weight of the lubricating oil composition. The lubricating oil composition according to claim 5 or 6 , which is used for gear oil.