JP5797543B2 - Viscosity index improver and lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition containing a viscosity index improver and a viscosity index improver.

Lubricating oils and hydraulic oils used in automobiles and the like have a lower viscosity as the temperature increases, but in practice, it is desirable that the viscosity does not change as much as possible over a wide range from a low temperature to a high temperature. Therefore, a method for improving the temperature dependence of viscosity by adding a viscosity index improver to lubricating oil is widely used. As such a viscosity index improver, a methacrylic acid ester copolymer (Patent Documents 1 to 3), an olefin copolymer (Patent Document 4) and the like are known.
However, the above-described viscosity index improver is not yet sufficiently effective in improving the viscosity index, and when added to the lubricating oil composition, there is a problem that the viscosity at a low temperature of the lubricating oil composition increases.

Japanese Patent No. 2732187 JP-A-8-53683 JP 2004-307551 A JP 2005-200454 A

  An object of the present invention is to provide a viscosity index improver that has a high effect of improving the viscosity index and hardly increases the low temperature viscosity of the lubricating oil composition.

As a result of intensive studies, the present inventors have arrived at the present invention. That is, the present invention provides a (co) polymer (A) having a polymerizable unsaturated group-containing polymer (Y) and a monomer (a) represented by the following general formula (1) as essential constituent monomers. (Y) is a polymer having at least one polymerizable unsaturated group-containing hydrocarbon compound (x) as a constituent monomer, and (Y) has A viscosity index improver having an average number of polymerizable unsaturated groups of 0.8 to 1.5 and a solubility parameter of (A) of 7.3 to 9.5 (cal / cm ³ ) ^1/2 , And a lubricating oil composition comprising the viscosity index improver and a base oil.

R ¹ is a hydrogen atom or a methyl group; R ² is a group represented by —O— or —NH—; R ³ is an alkylene group having 2 to 4 carbon atoms; m is a number from 0 to 20; R ^{3 in the} above cases may be the same or different, and the (R ³ O) _m moiety may be a random bond or a block bond; R ⁴ is a branched alkyl group having 16 to 60 carbon atoms.

  The lubricating oil composition containing the viscosity index improver of the present invention has a high viscosity index improving effect and exhibits an effect that it is difficult to increase the low temperature viscosity of the lubricating oil composition.

The viscosity index improver of the present invention comprises a polymerizable unsaturated group-containing polymer (Y) and a monomer (a) represented by the following general formula (1) as essential constituent monomers. (Y) is a polymer comprising at least one polymerizable unsaturated group-containing hydrocarbon compound (x) as a constituent monomer, and (Y) is a polymerizable non-polymerizable compound. The average value of the saturated group number is 0.8 to 1.5, and the solubility parameter of (A) is 7.3 to 9.5 (cal / cm ³ ) ^1/2 .

  As the polymerizable unsaturated group-containing hydrocarbon compound (x), (1) aliphatic unsaturated hydrocarbon [olefin having 2 to 36 carbon atoms (for example, ethylene, propylene, butene, isobutene, pentene, heptene, diisobutylene, octene) , Dodecene, octadecene, triacocene, hexatriacene, etc.) and dienes having 2 to 36 carbon atoms (for example, butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.), etc.], (2 ) Alicyclic unsaturated hydrocarbons [for example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, ethylidenebicycloheptene, etc.], (3) aromatic group-containing unsaturated hydrocarbons (for example, styrene, α -Methylstyrene, vinyltoluene, 2,4-dimethylstyrene, Methylstyrene, isopropyl styrene, butyl styrene, phenyl styrene, cyclohexyl styrene, benzyl styrene, crotyl benzene, vinyl naphthalene, divinyl benzene, divinyl toluene, divinyl xylene and trivinyl benzene), and the like.

  Of the unsaturated hydrocarbons, aliphatic unsaturated hydrocarbons are preferable from the viewpoint of solubility in the lubricating oil composition, and propylene, butene, isobutylene, butadiene, and isoprene are more preferable. The (co) polymer (A) may be a polymer obtained from only one kind of the unsaturated hydrocarbon or a copolymer obtained from two or more kinds. In the case of a copolymer, it may be a block polymer or a random polymer.

The polymerizable unsaturated group-containing polymer (Y) includes a mixture of those having and having no polymerizable unsaturated group in (Y), but the average value of the number of polymerizable unsaturated groups in (Y). Is 0.8 to 1.5. Here, the average value of the number of polymerizable unsaturated groups possessed by (Y) is a value obtained by dividing the total number of polymerizable unsaturated groups possessed by (Y) by the total number of molecules of (Y). The average value of the number of polymerizable unsaturated groups possessed by (Y) is preferably 0.85 to 1.3, more preferably 0.9 to 1.2, from the viewpoint of viscosity index improving ability and suppression of insoluble components. Particularly preferred is 0.9 to 1.1.
The average value of the number of polymerizable unsaturated groups possessed by (Y) can be calculated by the following formula.

[Average value of the number of polymerizable unsaturated groups possessed by (Y)] = [Number average molecular weight of (Y)] / [Iodine value of (Y)] / (2.54 × 10 ⁴ )
Here, the number average molecular weight (hereinafter abbreviated as Mn) of (Y) can be measured by the GPC method described later, and the iodine value of (Y) can be measured according to the method described in JISK0070.

  The polymerizable unsaturated group-containing polymer (Y) has an active hydrogen group-containing polymer (X) having (x) as a constituent monomer and a functional group capable of reacting with at least one active hydrogen group. A polymer obtained by bonding the polymerizable unsaturated compound (p) is preferable.

  Examples of the active hydrogen group-containing polymer (X) include a hydroxyl group-containing polymer (X1), an amino group-containing polymer (X2), a carboxyl group-containing polymer (X3), and a thiol group-containing polymer (X4). . Of these, (X1) and (X3) are preferable.

Examples of the hydroxyl group-containing polymer (X1) include the following.
Obtained by adding alkylene oxide (ethylene oxide, propylene oxide, etc.) to a polymer obtained by polymerizing alkylene oxide adduct (X1-1); (x) in the presence of an ion polymerization catalyst (sodium catalyst, etc.). Etc.
Hydroboration product (X1-2); hydroboration reaction product of polymer (x) having a terminal double bond (for example, those described in US Pat. No. 4,316,973) and the like.
Hydroformyl-hydride (X1-3): a product obtained by hydroformylating a polymer of (x) having a terminal double bond and then hydrogenating (for example, those described in JP-A-63-175096) etc.
Maleic anhydride-ene-aminoalcohol adduct (X1-4); a reaction product obtained by the ene reaction of a polymer (x) having a terminal double bond with maleic anhydride is imidized with aminoalcohol. What was obtained.
Among (X1), (X1-1), (X1-2) and (X1-4) are preferable, and more preferable are (X1-1) ethylene oxide adduct and (X1- 4).

  Examples of the carboxyl group-containing polymer (X2) include an ene reaction product of the polymer (x) having an unsaturated group at the terminal and anhydrous maleate.

  Examples of the amino group-containing polymer (X3) include those obtained by hydroformylating the polymer (x) having a terminal double bond and then amination (for example, those described in EP0628575). .

  The thiol group-containing polymer (X4) is obtained by polymerizing a polymer of (x) having a terminal double bond and a thiol group-containing monomer such as vinyl-2-ethylmercaptoethyl ether. (For example, those described in JP-A-2009-227982).

The amount of methyl groups in (X) is preferably from 200 to 500 (unit: / 1,000 C), more preferably from 220 to 500, from the viewpoint of the low-temperature viscosity characteristics of (A) and the solubility in the lubricating oil composition. 480, particularly preferably 250 to 450, most preferably 280 to 420.
Here, the amount of methyl groups in (X) is the total number of carbon atoms derived from methyl groups per unit carbon number (1,000 C) of (X), and “Nioclet FTIR system” [Thermo Fisher Scientific By Hook Co., Ltd.].

The polymerizable unsaturated compound (p) having a functional group capable of reacting with at least one active hydrogen group is a compound having one active hydrogen group and at least one polymerizable unsaturated group.
Examples of the active hydrogen group possessed by (p) include a hydroxyl group, an amino group, an imino group, a carboxyl group, and a thiol group.
(P) includes a hydroxyl group-containing polymerizable unsaturated compound (p1), an amino group-containing polymerizable unsaturated compound (p2), a carboxyl group-containing polymerizable unsaturated compound (p3), and a thiol group-containing polymerizable unsaturated compound ( p4) and the like.

  (P1) includes monohydroxy substituted unsaturated hydrocarbon (p1-1), monoester of unsaturated monocarboxylic acid and dihydric alcohol (p1-2), mono of unsaturated dihydric alcohol and monocarboxylic acid Examples include ester (p1-3), phenol (p1-4) having an alkenyl group, and unsaturated polyether monool (p1-5).

  Examples of the monohydroxy-substituted unsaturated hydrocarbon (p1-1) include alkenols having 3 to 6 carbon atoms such as (meth) allyl alcohol, 2-buten-1-ol, 3-buten-2-ol and 3-butene- 1-ol etc.]; and alkynols having 3 to 6 carbon atoms (for example, propargyl alcohol etc.) and the like. “(Meth) allyl” means allyl or methallyl.

As monoester (p1-2) of unsaturated monocarboxylic acid and dihydric alcohol, for example, C3-C8 unsaturated monocarboxylic acid (for example, acrylic acid) such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, etc. , Methacrylic acid, crotonic acid, itaconic acid and the like) and monoesters of the C2-C12 dihydric alcohols (e.g., ethylene glycol, propylene glycol and butylene glycol).
Specific examples of (p1-2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Examples include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. “(Meth) acrylate” means acrylate or methacrylate.

  As monoester (p1-3) of unsaturated dihydric alcohol and monocarboxylic acid, monoester of unsaturated dihydric alcohol having 3 to 8 carbon atoms and monocarboxylic acid having 2 to 12 carbon atoms (for example, butenediol Acetic acid monoester and the like).

Examples of the phenol (p1-4) having an alkenyl group include phenol having an alkenyl group having 2 to 8 carbon atoms.
Specific examples of (p1-4) include hydroxystyrene and hydroxy-p-methylstyrene.

  As the unsaturated polyether monool (p1-5), an alkylene oxide (having 2 to 8 carbon atoms) of 1 to 50 mol of the above (p1-1) or (p1-4) [for example, polyoxyethylene (degree of polymerization) 2-10) monoallyl ether] and the like.

  Examples of the amino group-containing polymerizable unsaturated compound (p2) include polymerizable unsaturated group-containing amines [mono- or di- (meth) allylamine and the like], aminoalkyl (2 to 4 carbon atoms) (meth) acrylate [aminoethyl]. (Meth) acrylates, etc.] and monoalkyl (C1-12) aminoalkyl (C2-4) (meth) acrylate (monomethylaminoethyl methacrylate, etc.).

Examples of the carboxyl group-containing polymerizable unsaturated compound (p3) include compounds having a carboxyl group and a polymerizable double bond.
Specific examples of (p3) include acrylic acid, methacrylic acid, crotonic acid and itaconic acid.

  Examples of the thiol group-containing polymerizable unsaturated compound (p4) include those in which the hydroxyl group of the (p1) is substituted with a thiol group.

  Examples of (p) include those having two or more polymerizable unsaturated bonds. Examples of such (p) include poly (meth) allyl ethers of polyhydric alcohols of 3 to 8 or more polyhydric alcohols or polyesters with unsaturated carboxylic acids [eg trimethylolpropane diallyl ether, pentaerythritol triallyl ether. And glycerin di (meth) acrylate and the like].

  Examples of the polymerizable unsaturated group possessed by (p) include a polymerizable double bond and a polymerizable triple bond. Of these, a polymerizable double bond is preferred. (P) The number of polymerizable unsaturated groups in one molecule is preferably 1 to 3, and more preferably 1.

  Of (p), (p1) and (p3) are preferred, (p1) is more preferred, and (p1-1), (p1-2) and (p1-4) are particularly preferred. Most preferred are monoesters of (meth) acrylic acid with ethylene glycol, propylene glycol or butylene glycol, allyl alcohol and hydroxy-α-methylstyrene, more preferred are 2-hydroxy Ethyl (meth) acrylate. “(Meth) acrylic acid” means acrylic acid or methacrylic acid.

  Mn of (p) is preferably 58 to 500, more preferably 58 to 300.

Although the manufacturing method of (Y) in case (Y) is a polymer by which (X) and (p) are couple | bonded, it does not specifically limit, The following are mentioned as a preferable manufacturing method.
(1) A carboxyl group-containing polymerizable unsaturated compound (p3) and an amino group-containing polymer (X3), a thiol group-containing polymer (X4) or a hydroxyl group-containing polymer (X1) are esterified and transesterified. A method of reaction, amidation reaction or thioesterification reaction.
(2) An amino group-containing polymerizable unsaturated compound (p2), a thiol group-containing polymerizable unsaturated compound (p4) or a hydroxyl group-containing polymerizable unsaturated compound (p1), and a carboxyl group-containing polymer (X2). Esterification reaction, transesterification reaction, amidation reaction or thioesterification reaction.
(3) A method in which polyisocyanate is added to a mixture of (X) and (p) and, if necessary, the reaction is carried out in the presence of a catalyst.
Among (1) to (3), (1) and (2) are preferable from the viewpoint that (Y) with a small amount of by-products can be obtained.

Mn of (Y) is preferably 500 to 50,000, more preferably 600 to 20,000, and particularly preferably 8,000 to 10,000 from the viewpoints of viscosity index improving ability and industrial productivity. The number average molecular weight (hereinafter abbreviated as Mw) of (Y) Mn and the (co) polymer (A) described later can be measured by gel permeation chromatography under the following conditions.
<Measurement conditions of Mn of (Y) and Mw of (A)>
Apparatus: “HLC-802A” [manufactured by Tosoh Corporation]
Column: Two “TSK gel GMH6” [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C.
Sample solution: 0.5 wt% tetrahydrofuran solution Solution injection amount: 200 μl
Detection device: 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]

(Y) preferably has a specific solubility parameter (hereinafter abbreviated as SP value) from the viewpoint of solubility in lubricating oil. The range of SP value becomes like this. Preferably it is 7.0-9.0 (cal / cm < ³ >) < ^1/2 >, More preferably, it is 7.1-8.5 (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 SP value of (Y) is calculated based on the SP value of each monomer constituting (Y) by the above-mentioned method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (Y) can be adjusted to a desired range by appropriately adjusting the SP value and the mole fraction of the monomer used.

When (X) constituting (Y) is a homopolymer of (x), the crystallization temperature of (Y) is preferably −40 ° C. or less from the viewpoint of the low temperature viscosity of the lubricating oil composition, More preferably, it is -50 degrees C or less, Most preferably, it is -55 degrees C or less, Most preferably, it is -60 degrees C or less.
The crystallization temperature of (Y) was determined by using a differential scanning calorimeter “Unix DSC7” (manufactured by PERKIN-ELMER), using (Y) 5 mg as a sample at an isothermal rate of 10 ° C./min. It is the crystallization temperature observed when cooled to 80 ° C.

The (co) polymer (A) in the present invention comprises the monomer (a) represented by the general formula (1) as an essential constituent monomer.
R ¹ in the general formula (1) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of improving the viscosity index.

R ² in the general formula (1) is a group represented by —O— or —NH—. Among these, the group represented by —O— is preferable from the viewpoint of the effect of improving the viscosity index.

R ³ in the general formula (1) is an alkylene group having 2 to 4 carbon atoms. Examples of the alkylene group having 2 to 4 carbon atoms include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3- or 1,4-butylene group. Among these, the ethylene group and the 1,2-propylene group are preferable from the viewpoint of the effect of improving the viscosity index.

M in the general formula (1) is a number from 0 to 20, preferably from 0 to 5, more preferably from 0 to 2 from the viewpoint of the effect of improving the viscosity index and low temperature viscosity.
When m is 2 or more, A may be the same or different, and the (R ³ O) _m moiety may be a random bond or a block bond.

R ⁴ in the general formula (1) is a branched alkyl group having 16 to 60 carbon atoms.
Examples of the branched alkyl group having 16 to 60 carbon atoms include isohexadecyl group, 2-octylnonyl group, 2-hexylundecyl group, 2-ethylpentadecyl group, 2- (3-methylhexyl) -7-methyl- Nonyl group, isooctadecyl group, 1-hexyltridecyl group, 2-ethylheptadecyl group, 2-octylundecyl group, isoicosyl group, 1-undecyldodecyl group, 1-octylpentadecyl group, 2-decyltridecyl group, 2-decyltetradecyl group, 2- (1,4,4-trimethylbutyl) -5,7,7-trimethyl-heptyl group, 2-dodecylpentadecyl group, isotricontyl group, 2-tetradecylheptadecyl group, 2 -Hexadecyl heptadecyl group, 1-heptyltricontyl group, 2-heptadecylicosyl group, 1-octadecylico Group, 2-hexadecyl docosyl group, 2- (1,4,4-trimethylbutyl) -5,7,7-trimethyl-tricontyl group, 2-icosyl docosyl group, 1-icosyl tetracosyl group, 2 -Ethyl-4-butyl-tetracontyl group, 2-tetracosylhexacosyl group, 2-methylpentacontyl group, 2-tetradecyltetracontyl group, 2-dodecylhexatetracontyl group, 2- (3- Methylhexyl) -7-ethyl-pentacontyl group, 1-octacosyltricontyl group, 1-icosyltetracontyl group, 2-decylpentacontyl group and olefin [for example, propylene oligomer (13 to 20-mer), ethylene / Propylene oligomer (18-28 mer, molar ratio 16/1 to 1/11) and isobutene oligomer (10-15 mer), etc.] Residue excluding hydroxyl group, and the like from oxo alcohols obtained al.
Of the branched alkyl groups having 16 to 60 carbon atoms, preferred are branched alkyl groups having 16 to 50 carbon atoms, and more preferred are branched alkyl groups having 16 to 44 carbon atoms, particularly from the viewpoint of improving the viscosity index. A branched alkyl group having 20 to 40 carbon atoms is preferred.

  Specific examples of the monomer (a) include isohexadecyl (meth) acrylate, 2-octylnonyl (meth) acrylate, ester of ethylene glycol mono-2-ethylpentadecyl ether and (meth) acrylic acid. , Isooctadecyl (meth) acrylate, 1-hexyltridecyl (meth) acrylate, 2-ethylheptadecyl (meth) acrylate, isoicosyl (meth) acrylate, 1-octylpentadecyl (meth) acrylate, ( (Meth) acrylic acid 2-decyltetradecyl, (meth) acrylic acid 2-dodecylpentadecyl, (meth) acrylic acid isotricontyl, (meth) acrylic acid 2-tetradecylheptadecyl, (meth) acrylic acid 2-hexadecylhepta Decyl, 2-heptadecyl icosyl (meth) acrylate, (meth) acrylic 2-hexadecyl docosyl, 2-methosyl acrylate (meth) acrylate, 2-tetracosyl hexacosyl (meth) acrylate, 2-methylpentacontyl (meth) acrylate, 2-tetradecyl (meth) acrylate Oxoalcohol and (meth) acrylic obtained from tetracontyl, (meth) acrylic acid 2-dodecylhexatetracontyl, (meth) acrylic acid 1-octacosyltricontyl, and propylene oligomer (13-20 mer) Examples include esters with acids.

(A) SP value is 7.3-9.5 (cal / cm < ³ >) < ^1/2 >, Preferably it is 9.0-9 from a viewpoint of the viscosity index improvement effect and the low temperature viscosity of a lubricating oil composition. 0.5 (cal / cm ³ ) ^1/2 , more preferably 9.1 to 9.3 (cal / cm ³ ) ^1/2 .
The SP value of (A) is calculated based on the SP value of each monomer constituting (A) by the above method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (A) can be adjusted to 7.3 to 9.5 (cal / cm ³ ) ^1/2 by appropriately adjusting the SP value and molar fraction of the monomer used.

The absolute value of the difference between the SP value of (A) and the SP value of the base oil is preferably 0.5 to 1.2 (cal / cm ³ ) from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. ^1/2, more preferably ^{0.6~1.0 (cal / cm 3) 1/2} , particularly preferably ^{0.7~0.9 (cal / cm 3) 1/2} .

  (A) is a (meth) acrylic acid alkyl ester (b) having a linear alkyl group having 1 to 4 carbon atoms and / or a linear alkyl group having 8 to 36 carbon atoms in addition to the monomer (a). It is preferable from a viewpoint of a viscosity index improvement effect that it is a copolymer which has the (meth) acrylic-acid alkylester (c) which has as a structural monomer.

Examples of the (meth) acrylic acid alkyl ester (b) having a linear alkyl group having 1 to 4 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) ) N-butyl acrylate.
Of these, (b) is preferably a (meth) acrylic acid ester having a linear alkyl group having 1 to 3 carbon atoms, more preferably methyl (meth) acrylate and ethyl (meth) acrylate, Particularly preferred is methyl (meth) acrylate.

As the (meth) acrylic acid alkyl ester (c) having a linear alkyl group having 8 to 36 carbon atoms, (meth) acrylic acid n-tetradecyl, (meth) acrylic acid n-pentadecyl, (meth) acrylic acid n- Hexadecyl, n-octadecyl (meth) acrylate, n-icosyl (meth) acrylate, n-tetracosyl (meth) acrylate, n-triacontyl (meth) acrylate, n-hexatriacontyl (meth) acrylate, etc. Is mentioned.
Among (c), (meth) acrylic acid alkyl ester having a linear alkyl group having 12 to 32 carbon atoms is preferred, and (meth) acrylic having a linear alkyl group having 16 to 30 carbon atoms is more preferred. Acid esters, particularly preferred are (meth) acrylic acid esters having linear alkyl having 18 to 28 carbon atoms.

(A) is a copolymer further comprising a nitrogen atom-containing vinyl monomer (d), a hydroxyl group-containing vinyl monomer (e) and / or a phosphorus atom-containing vinyl monomer (f) as a constituent monomer. It is preferable from the viewpoint of the effect of improving the viscosity index.
Examples of the nitrogen atom-containing vinyl monomer (d) include the following monomers (d1) to (d4).

Amide group-containing vinyl monomer (d1):
(Meth) acrylamide, monoalkylamino (meth) acrylamide [nitrogen atom having one alkyl group having 1 to 4 carbon atoms bonded thereto; for example, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N- Isopropyl (meth) acrylamide and Nn- or isobutyl (meth) acrylamide, etc.], monoalkylaminoalkyl (meth) acrylamide [aminoalkyl group in which one alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom (carbon number 2-6); for example N-methylaminoethyl (meth) acrylamide, N-ethylaminoethyl (meth) acrylamide, N-isopropylamino-n-butyl (meth) acrylamide and Nn- or isobutylamino- n-butyl (meth) acrylamide etc.], dialkyl Mino (meth) acrylamide [nitrogen atom having two alkyl groups having 1 to 4 carbon atoms bonded; for example, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-diisopropyl (Meth) acrylamide and N, N-di-n-butyl (meth) acrylamide, etc.], dialkylaminoalkyl (meth) acrylamide [aminoalkyl group in which two alkyl groups having 1 to 4 carbon atoms are bonded to a nitrogen atom (carbon Having 2 to 6); for example, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide and N, N-di -N-butylaminobutyl (meth) acrylamide etc.], N-vinylcarboxylic acid amide [ - vinyl formamide, N- vinyl acetamide, include those having a N- vinyl -n- or isopropionyl and N- vinyl-hydroxyacetamide etc.] amide groups only on the nitrogen atom and the like.

Nitro group-containing monomer (d2):
4-nitrostyrene etc. are mentioned.

Primary to tertiary amino group-containing vinyl monomer (d3):
Primary amino group-containing vinyl monomer {alkenylamine having 3 to 6 carbon atoms [(meth) allylamine, crotylamine, etc.], aminoalkyl (2 to 6 carbon atoms) (meth) acrylate [aminoethyl (meth) acrylate, etc.] }; Secondary amino group-containing vinyl monomer {monoalkylaminoalkyl (meth) acrylate [having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group having 1 to 6 carbon atoms is bonded to a nitrogen atom] For example, t-butylaminoethyl (meth) acrylate and methylaminoethyl (meth) acrylate, etc.], C 6-12 dialkenylamine [di (meth) allylamine, etc.}}; tertiary amino group-containing vinyl monomer {Dialkylaminoalkyl (meth) acrylate [Aminoalkyl having two alkyl groups having 1 to 6 carbon atoms bonded to a nitrogen atom] Having a sulfur group (2 to 6 carbon atoms); for example, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, etc.], alicyclic (meth) acrylate having a nitrogen atom [morpholinoethyl (meth) acrylate, etc. ], Aromatic vinyl monomers [diphenylamine (meth) acrylamide, N, N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc. ], And their hydrochlorides, sulfates, phosphates or lower alkyl (C 1-8) monocarboxylic acids (such as acetic acid and propionic acid) salts.

Nitrile group-containing vinyl monomer (d4):
Examples include (meth) acrylonitrile.

  Among (d), (d1) and (d3) are preferred, and diphenylamine (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) are more preferred. ) Acrylamide, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

Examples of the hydroxyl group-containing vinyl monomer (e) include the following monomers (e1) to (e2).
Hydroxyl group-containing vinyl monomer (e1);
Hydroxyl group-containing aromatic vinyl monomer (p-hydroxystyrene etc.), hydroxyalkyl (2 to 6 carbon atoms) (meth) acrylate [2-hydroxyethyl (meth) acrylate, and 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, C3-C12 alkenol [(meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1-undecenol etc.], C4-12 alkene monool or al Diols [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (1 to 6 carbon atoms) alkenyl (3 to 10 carbon atoms) ether (2 -Hydroxyethylpropenyl ether, etc.), polyvalent (3-8 valent) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, saccharides, sucrose, etc.) alkenyl (carbon number 3-10) ether or (meth) acrylate [Sucrose (meth) allyl ether etc.] etc. are mentioned.

Polyoxyalkylene chain-containing vinyl monomer (e2);
Polyoxyalkylene glycol (alkylene group having 2 to 4 carbon atoms, polymerization degree 2 to 50), polyoxyalkylene polyol [polyoxyalkylene ether of 3 to 8 valent alcohol (alkylene group having 2 to 4 carbon atoms, polymerization degree) 2-100)], mono (meth) acrylates of polyoxyalkylene glycol or polyoxyalkylene polyol alkyl (carbon number 1-4) ether [polyethylene glycol (Mn: 100-300) mono (meth) acrylate, polypropylene glycol ( Mn: 130-500) mono (meth) acrylate, methoxypolyethylene glycol (Mn: 110-310) (meth) acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth) acrylate and mono (meth) acryl Polyoxyethylene (Mn: 150 to 230), sorbitan, etc.] and the like.

  (E) is preferably (e1), more preferably 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, N, N-dihydroxypropyl (meth) acrylamide. And vinyl alcohol.

  Examples of the phosphorus atom-containing monomer (f) include the following monomers (f1) to (f2).

Phosphate group-containing monomer (f1):
(Meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphoric acid ester [(meth) acryloyloxyethyl phosphate and (meth) acryloyloxyisopropyl phosphate] and phosphoric acid alkenyl ester [vinyl phosphate, allyl phosphate, Propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, dodecenyl phosphate, etc.].

Phosphono group-containing monomer (f2):
(Meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphonic acid [(meth) acryloyloxyethylphosphonic acid etc.] and alkenyl (2 to 12 carbon atoms) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid and octenyl phosphonic acid Etc.].

  Of these, (f1) is preferred among (f), (meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphate is more preferred, and (meth) acryloyloxyethyl phosphate is particularly preferred. It is.

  In addition to the monomers (a) to (f), (A) may use the following monomers (g) to (m) as constituent monomers.

Aliphatic hydrocarbon vinyl monomer (g):
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 and 1,7-octadiene).

Alicyclic hydrocarbon vinyl monomer (h):
Examples include cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, and ethylidenebicycloheptene.

Aromatic hydrocarbon vinyl monomer (i):
Styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-chloro Examples include tilbenzene and 2-vinylnaphthalene.

Vinyl esters, vinyl ethers, vinyl ketones (j):
Vinyl esters of saturated fatty acids having 2 to 12 carbon atoms (such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl octoate), alkyl, aryl or alkoxyalkyl vinyl ethers having 1 to 12 carbon atoms (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether) Butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl-2-methoxyethyl ether and vinyl-2-butoxyethyl ether) and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms (methyl vinyl ketone, ethyl vinyl ketone and Phenyl vinyl ketone, etc.).

Epoxy group-containing vinyl monomer (k):
Examples thereof include glycidyl (meth) acrylate and glycidyl (meth) allyl ether.

Halogen element-containing vinyl monomer (l):
Examples thereof include vinyl chloride, vinyl bromide, vinylidene chloride, (meth) allyl chloride and halogenated styrene (dichlorostyrene and the like).

Unsaturated polycarboxylic acid ester (m):
Alkyl, cycloalkyl or aralkyl ester of unsaturated polycarboxylic acid [alkyl diester having 1 to 8 carbon atoms of unsaturated dicarboxylic acid (such as maleic acid, fumaric acid and itaconic acid) (dimethyl maleate, dimethyl fumarate, diethyl maleate) And dioctyl maleate)] and the like.

The proportion of (Y) constituting (A) is preferably 1 to 50% by weight, more preferably, based on the weight of (A), from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. Is 5 to 45% by weight, particularly preferably 10 to 40% by weight.
The proportion of (a) constituting (A) is preferably 1 to 50% by weight, more preferably, based on the weight of (A), from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. Is 5 to 45% by weight, particularly preferably 10 to 40% by weight.
The proportion of (b) constituting (A) is preferably 5 to 70% by weight, more preferably, based on the weight of (A), from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. Is 10 to 65% by weight, particularly preferably 20 to 60% by weight.
The proportion of (c) constituting (A) is preferably 0 to 70% by weight, more preferably, based on the weight of (A), from the viewpoint of the viscosity index improving effect and the low temperature viscosity of the lubricating oil composition. Is 10 to 60% by weight, particularly preferably 20 to 50% by weight.
The proportion of (d) to (f) constituting (A) is preferably 0 to 15% by weight based on the weight of (A), from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. More preferably 1 to 12% by weight, particularly preferably 2 to 10% by weight.
The proportion of (g) to (m) constituting (A) is preferably 0 to 10% by weight based on the weight of (A) from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. More preferably 1 to 7% by weight, particularly preferably 2 to 5% by weight.

  Mw of (A) is preferably 5,000 to 1,000,000 from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition, and the more preferable range varies depending on the use of the lubricating oil composition. The ranges are listed in Table 1.

*: Automatic transmission oil
**: Belt-Continuously variable transmission oil
***: Manual transmission oil

The crystallization temperature of (A) is preferably −30 ° C. or less, more preferably −40 ° C. or less, and particularly preferably −50 ° C. or less from the viewpoint of the low temperature viscosity of the lubricating oil composition.
In addition, the crystallization temperature of (A) can be measured by the method similar to the measuring method of the crystallization temperature of said (Y).

(A) can be obtained by a known production method, and specifically includes a method obtained by solution polymerization of the above monomer in a solvent in the presence of a polymerization catalyst.
Examples of the solvent include toluene, xylene, alkylbenzene having 9 to 10 carbon atoms, methyl ethyl ketone, and 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 a tertiary amine and the like. Furthermore, if necessary, a known chain transfer agent (such as an alkyl mercaptan having 2 to 20 carbon atoms) can also 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 addition polymer or an alternating copolymer, and may be either a graft copolymer or a block copolymer.

The viscosity index improver of the present invention may be used in combination with (A) and an alkyl (meth) acrylate (co) polymer (B) other than (A).
(B) is not particularly limited as long as it is an alkyl (meth) acrylic acid ester (co) polymer other than (A), but a (meth) acrylic acid alkyl ester having a linear alkyl group having 1 to 15 carbon atoms. Examples include (co) polymers.
Specific examples of (B) include n-octadecyl methacrylate / n-dodecyl methacrylate (molar ratio 10-30 / 90-70) copolymer, n-tetradecyl methacrylate / n-dodecyl methacrylate (molar ratio 10). -30 / 90-70) Copolymer, n-hexadecyl methacrylate / n-dodecyl methacrylate / methyl methacrylate (molar ratio 20-40 / 55-75 / 0-10) copolymer and n-dodecyl acrylate / N-dodecyl methacrylate (molar ratio 10 to 40/90 to 60) copolymer and the like, and these may be used alone or in combination of two or more.

  When (A) and (B) are used in combination, the amount of (B) used is preferably 0.01 to 30% by weight based on the weight of (A) from the viewpoint of the low temperature viscosity of the lubricating oil composition. More preferably, the content is 0.01 to 20% by weight, and particularly preferably 0.01 to 10% by weight.

  The lubricating oil composition of the present invention comprises the viscosity index improver of the present invention and a base oil. Base oils 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 synthetic lubricating oils) (Poly-α-olefin-based synthetic lubricating oil, etc.) and ester-based synthetic lubricating oil, etc.] and mixtures thereof. Of these, mineral oil is preferred.

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

  The cloud point (measured according to JIS-K2269) of the base oil 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 good.

The content of the viscosity index improver in the lubricating oil composition of the present invention is preferably 1 to 30% by weight in terms of the weight of (A) in the viscosity index improver based on the weight of the base oil. .
When the lubricating oil composition is used as an engine oil, a base oil having a kinematic viscosity at 100 ° C. of 4 to 10 mm ² / s and containing 2 to 10% by weight of (A) is preferable.
When the lubricating oil composition is used as a gear oil, a base oil having a kinematic viscosity at 100 ° C. of ² to 10 mm ² / s and containing 3 to 30% by weight of (A) is preferable.
When the lubricating oil composition is used as an automatic transmission oil (such as ATF and belt-CVTF), a base oil having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s and 3 to 25% by weight of (A) What is contained is preferable.
When the lubricating oil composition is used as a traction oil, a base oil having a kinematic viscosity at 100 ° C. of 1 to 5 mm ² / s and containing (A) of 0.5 to 10% by weight is preferable. .

The lubricating oil composition of the present invention may contain various additives. The following are mentioned as an additive.
(1) Detergent:
Basic, overbased or neutral metal salts [overbased or alkaline earth metal salts of sulfonates (such as petroleum sulfonates, alkylbenzene sulfonates and alkylnaphthalene sulfonates)], salicylates, phenates, naphthenates , Carbonates, phosphonates and mixtures thereof;
(2) Dispersant:
Succinimides (bis- or mono-polybutenyl succinimides), Mannich condensation products, borates and the like;
(3) Antioxidant:
Hindered phenols and aromatic secondary amines, etc .;
(4) Oiliness improver:
Long chain fatty acids and their esters (such as oleic acid and oleic acid esters), long chain amines and their amides (such as oleylamine and oleylamide), etc .;
(5) Friction and wear modifier:
Molybdenum and zinc compounds (such as molybdenum dithiophosphate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate);
(6) Extreme pressure agent:
Sulfur compounds (mono or disulfides, sulfoxides and sulfur phosphide compounds), phosphide compounds and chlorinated compounds (chlorinated paraffins, etc.);
(7) Antifoaming agent:
Silicon oil, metal soap, fatty acid ester and phosphate compound, etc .;
(8) Demulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphates (polyoxyethylene-containing nonionic surfactant phosphates, etc.);
(9) Corrosion inhibitor:
Nitrogen atom-containing compounds (such as benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate) and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
<Production Example 1>
Hydrogenated polybutadiene “NISSO-PB containing hydroxyl groups at both ends in a reaction vessel equipped with a temperature control device, a vacuum stirring blade, a decompression device, a Dimroth condenser, a fractionation tube, a flask for receiving a distillate, a nitrogen inlet and an outlet. GI-1000 "[Mn: 1,500, manufactured by Nippon Soda Co., Ltd.] 200 parts by weight, 9.2 parts by weight of methacrylic acid, 200 parts by weight of xylene and 1 part by weight of para-toluenesulfonic acid were added and stirred at 130 ° C. The temperature was raised to. Next, an esterification reaction was performed at 130 ° C. for 4 hours, and distillate water was separated. Further cooled to 25 ° ^C., it was confirmed esterification reaction product in 1 H-NMR (98 mol% yield). 300 parts by weight of a 10% by weight aqueous sodium hydrogen carbonate solution was added and stirred to sufficiently neutralize paratoluenesulfonic acid. The supernatant liquid was collected with a separatory funnel, heated to 120 to 130 ° C., and unreacted monomers and xylene were removed under reduced pressure (0.027 to 0.040 MPa) at the same temperature over 2 hours. 1) was obtained. Mn of (Y-1): 1600, polymerizable unsaturated group number: 0.8, methyl group number: 350 / 1,000 C, crystallization temperature of (Y-1): ≦ −80 ° C.

<Production Example 2>
In a reaction vessel equipped with a temperature control device, a vacuum stirring blade, a nitrogen inlet and an outlet, terminal unsaturated group-containing polybutene “Nissan Polybutene 3N” [Mn: 700, manufactured by NOF Corporation], 280 parts by weight, tetrahydrofuran- 400 parts by weight of a boron / tetrahydrofuran 1 mol / L solution [manufactured by Wako Pure Chemical Industries, Ltd.] and 400 parts by weight of tetrahydrofuran were added, and hydroboration was performed at 25 ° C. for 4 hours. Subsequently, 50 parts by weight of water, 50 parts by volume of 3N-NaOH aqueous solution, and 50 parts by volume of 30% by weight hydrogen peroxide were added to oxidize. The supernatant liquid was collected with a separatory funnel, and after raising the temperature to 50 ° C., tetrahydrofuran was removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 2 hours to obtain a hydroxyl group-containing polymer (X-2). Got.
(X-2) 200 parts by weight, methacrylic acid in a reaction vessel equipped with a temperature controller, vacuum stirring blade, decompressor, Dimroth condenser, fractionator, distillate receiving flask, nitrogen inlet and outlet 50 parts by weight, 200 parts by weight of xylene and 1 part by weight of paratoluenesulfonic acid were added, and the temperature was raised to 130 ° C. with stirring. Next, an esterification reaction was performed at 130 ° C. for 4 hours, and distillate water was separated. Further cooled to 25 ° ^C., it was confirmed esterification reaction product in 1 H-NMR (98 mol% yield). 300 parts by weight of a 10% by weight aqueous sodium hydrogen carbonate solution was added and stirred to sufficiently neutralize paratoluenesulfonic acid. The supernatant liquid was collected with a separatory funnel, heated to 120 to 130 ° C., and unreacted monomers and xylene were removed under reduced pressure (0.027 to 0.040 MPa) at the same temperature over 2 hours. 2) was obtained. Mn of (Y-2): 750, number of polymerizable unsaturated groups: 1.0, number of methyl groups: 380 / 1,000 C, crystallization temperature of (Y-2): ≦ −80 ° C.

<Production Example 3>
In a pressure-resistant reaction vessel made of SUS equipped with a temperature control device and a stirrer, 530 parts by weight of polyunsene containing terminal unsaturated group “Nissan Polybutene 200N” [Mn: 2,650, manufactured by NOF Corporation] and maleic anhydride [Japanese [Manufactured by Kojun Pharmaceutical Co., Ltd.] 25 parts by weight were added, the temperature was raised to 220 ° C. with stirring, and an ene reaction was performed at that temperature for 4 hours. Next, the mixture was cooled to 25 ° C., 20 parts by weight of 2-aminoethanol was added, the temperature was raised to 130 ° C. with stirring, and an imidization reaction was performed at the same temperature for 4 hours. Unreacted maleic anhydride and 2-aminoalcohol were removed over 2 hours at 120 to 130 ° C. under reduced pressure (0.027 to 0.040 MPa) to obtain a hydroxyl group-containing polymer (X-3).
(X-3) 200 parts by weight, methacrylic acid in a reaction vessel equipped with a temperature controller, vacuum stirring blade, decompression device, Dimroth condenser, fractionation tube, distillate receiving flask, nitrogen inlet and outlet 50 parts by weight, 200 parts by weight of xylene and 1 part by weight of paratoluenesulfonic acid were added, and the temperature was raised to 130 ° C. with stirring. Next, an esterification reaction was performed at 130 ° C. for 4 hours, and distillate water was separated. Further cooled to 25 ° ^C., it was confirmed esterification reaction product in 1 H-NMR (98 mol% yield). 300 parts by weight of a 10% by weight aqueous sodium hydrogen carbonate solution was added and stirred to sufficiently neutralize paratoluenesulfonic acid. The supernatant liquid was collected with a separatory funnel, heated to 120 to 130 ° C., and unreacted monomers and xylene were removed under reduced pressure (0.027 to 0.040 MPa) at the same temperature over 2 hours. 3) was obtained. Mn of (Y-3): 2,700, number of polymerizable unsaturated groups: 0.9, number of methyl groups: 400 / 1,000 C, crystallization temperature of (Y-3): ≦ −80 ° C.

<Examples 1-7, Comparative Examples 1-4>
Base oil (SP value: 8.3, kinematic viscosity at 100 ° C .: 4.2 mm ² / s, viscosity index: 128) 400 wt. Parts, 100 parts by weight of the monomer blend described in Table 2, 0.5 parts by weight of 2,2-azobis (2,4-dimethylvaleronitrile) and 2,2-azobis (2-methylbutyronitrile) ( (Hereinafter abbreviated as AIBN.) 0.2 parts by weight were added, and after nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76 ° C. with stirring in a sealed state, and the polymerization reaction was performed at the same temperature for 4 hours. Went. After raising the temperature to 120 to 130 ° C., unreacted monomers are removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 2 hours, and the copolymers (A1) to (A7), (H1) to (H Viscosity index improvers (R1) to (R7) and (S1) to (S4) comprising H4) were obtained. The SP values of the obtained copolymers (A1) to (A7) and (H1) to (H4) were calculated by the above method, and Mw and crystallization temperature were measured by the above method. Moreover, the base oil solubility of the viscosity index improver was evaluated by the following method. The results are shown in Table 2.

<Evaluation method of base oil solubility of viscosity index improver>
The appearance of the viscosity index improvers (R1) to (R7) and (S1) to (S4) was visually observed, and the base oil solubility was evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: Appearance is uniform and there is no insoluble matter in the copolymer ×: Appearance is inhomogeneous and insoluble matter in the copolymer is observed

The compositions of the monomers (a) to (f) described in Table 2 are as described below.
(A-1): 2-n-decyl methacrylate-n-tetradecyl methacrylate (b-1): methyl methacrylate (c-1): n-tetradecyl methacrylate (c-2): n-hexadecyl methacrylate (c -3): n-octadecyl methacrylate (d-1): N, N-dimethylaminoethyl methacrylate (e-1): hydroxyethyl methacrylate (f-1): methacryloyloxyethyl phosphate

<Examples 8 to 14 and Comparative Examples 5 to 8>
A base oil (SP value: 8.3, kinematic viscosity at 100 ° C .: 4.2 mm ² / s, viscosity index: 128) is charged into a stainless steel container equipped with a stirrer, and 150 of the resulting lubricating oil composition is obtained. Viscosity index improvers (R1) to (R31) and (S1) to (S12) were added so that the HTHS viscosity at 0 ° C. was 2.60 ± 0.05 (mm ² / s). Products (X1) to (X31) and (Y1) to (Y12) were obtained.
The viscosity index, HTHS viscosity (80 ° C.), and low temperature viscosity (−40 ° C.) of the lubricating oil compositions (X1) to (X31) and (Y1) to (Y12) were measured by the following methods. The results are shown in Table 3.

<Measuring method of viscosity index of lubricating oil composition>
It measured by the method of JIS-K2283.

<Method for Measuring HTHS Viscosity of Lubricating Oil Composition>
The measurement was performed at 80 ° C. by the method of ASTM D 5481.

<Method for measuring low temperature viscosity of lubricating oil composition>
The viscosity at −40 ° C. was measured by the method of JPI-5S-26-85.

  As is clear from the results in Table 3, the lubricating oil compositions (Examples 8 to 14) containing the viscosity index improver of the present invention were compared with the lubricating oil compositions of Comparative Examples 5 to 8, High viscosity index improvement effect and low temperature viscosity.

The lubricating oil composition containing the viscosity index improver of the present invention includes a drive system lubricating oil (manual transmission oil, differential gear oil, automatic transmission oil, belt CVT oil, etc.), hydraulic oil (mechanical hydraulic oil, power Steering oil, shock absorber oil, etc.), engine oil (gasoline, diesel, etc.) and traction oil.

Claims (11)

It comprises a polymerizable unsaturated group-containing polymer (Y) and a (co) polymer (A) having a monomer (a) represented by the following general formula (1) as an essential constituent monomer. Viscosity index improver, wherein (Y) is a polymer having at least one polymerizable unsaturated group-containing hydrocarbon compound (x) as a constituent monomer, and (Y) has the number of polymerizable unsaturated groups The average value of A is 0.8 to 1.5, the solubility parameter of (A) is 7.3 to 9.5 (cal / cm ³ ) ^1/2 , and (A) is a constituent monomer. Based on the weight of (A), 1 to 50% by weight of (Y), 1 to 50% by weight of (a), 5 to 50% by weight of (b) and 0 to 70% by weight of (c) A viscosity index improver that is a copolymer .
[R ¹ is a hydrogen atom or a methyl group; R ² is a group represented by —O— or —NH—; R ³ is an alkylene group having 2 to 4 carbon atoms; m is a number of 0 to 20; R ^{3 in} the case of 2 or more may be the same or different, and the (R ³ O) _m moiety may be a random bond or a block bond; R ⁴ is a branched alkyl group having 16 to 60 carbon atoms. ]   (Y) reacts with an active hydrogen group-containing polymer (X) having at least one polymerizable unsaturated group-containing hydrocarbon compound (x) as a constituent monomer, and at least one active hydrogen group. The viscosity index improver according to claim 1, which is a polymer formed by bonding a polymerizable unsaturated compound (p) having a functional group capable of being bonded.   The number average molecular weight of (Y) is 500 to 50,000, The viscosity index improver according to claim 1 or 2.   The viscosity index improver according to claim 2 or 3, wherein the crystallization temperature of (Y) when (X) constituting (Y) is a homopolymer of (x) is -40 ° C or lower.   The viscosity index improver according to any one of claims 2 to 4, wherein the amount of methyl groups in (X) is 200 / 1,000C to 500 / 1,000C. (A) is a (meth) acrylic acid alkyl ester (b) having a linear alkyl group having 1 to 4 carbon atoms and / or a linear alkyl group having 8 to 36 carbon atoms as a constituent monomer of (A). The viscosity index improver according to any one of claims 1 to 5, which is a copolymer comprising (meth) acrylic acid alkyl ester (c).   (A) further includes a nitrogen atom-containing vinyl monomer (d), a hydroxyl group-containing vinyl monomer (e) and / or a phosphate group-containing vinyl monomer (f) as a constituent monomer of (A). The viscosity index improver according to any one of claims 1 to 6, wherein the viscosity index improver is a copolymer. The viscosity index improver according to any one of claims 1 to 7 , wherein (A) has a weight average molecular weight of 5,000 to 1,000,000. A lubricating oil composition comprising the viscosity index improver according to any one of claims 1 to 8 and a base oil. The lubricating oil composition according to claim 9, further comprising at least one additive selected from the group consisting of a dispersant, a detergent, an antioxidant, an oiliness improver, a friction wear modifier, and an extreme pressure agent. . The lubricating oil composition according to claim 9 or 10 , wherein the base oil has a kinematic viscosity at 100 ° C of 1 to 15 mm ² / s, and the base oil has a viscosity index of 90 or more.