JP6767249B2 - 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.

In recent years, in order to reduce CO ₂ emissions and protect petroleum resources, fuel efficiency of automobiles has been further demanded. One of the fuel efficiency reductions is the reduction of viscous resistance by reducing the viscosity of engine oil. However, when the viscosity is lowered, problems such as liquid leakage and seizure occur. In cold regions, low temperature startability is required. This problem is stipulated in the US SAE engine oil viscosity standard (SAE J300), and in the 0W-20 grade, the 150 ° C. HTHS viscosity (ASTM D4683 or D5481) under high temperature and high shear is Min. .. It is specified in 2.6. In addition, the same grade is specified to have a low temperature viscosity of 60,000 mPa · s or less at -40 ° C and no yield stress (ASTM D4684) in order to guarantee startability in cold regions. In order to save fuel consumption, an engine oil having a lower HTHS viscosity in the effective temperature range of 80 ° C. or 100 ° C. after satisfying the above standards is required, and various viscosity index improvers have been conventionally proposed. Known examples of such a viscosity index improver include methacrylate copolymers (Patent Documents 1 to 4), olefin copolymers (Patent Document 5), comb-type copolymers (Patent Documents 6 to 8), and the like. ing.
However, the above-mentioned viscosity index improver is not yet sufficient for reducing the viscosity of HTHS at 80 ° C. when added to an engine oil composition, is susceptible to a decrease in viscosity due to shearing, and has a problem that the viscosity at a low temperature increases. was there.

Japanese Patent No. 2732187 Japanese Patent No. 2754343 Japanese Patent No. 3831203 Japanese Patent No. 3999307 Japanese Unexamined Patent Publication No. 2005-2004 Japanese Patent No. 3474918 Japanese Patent Publication No. 2008-546894 Special Table 2010-532805

An object of the present invention is to provide a viscosity index improver which is excellent in shear stability of a lubricating oil composition, has a low HTHS viscosity in an effective temperature range of the lubricating oil composition, and has a high viscosity index of the lubricating oil composition. is there.

［Ｒ^１は水素原子又はメチル基；−Ｘ^１−は−Ｏ−、−Ｏ（ＡＯ）_ｍ−又は−ＮＨ−で表される基であって、Ａは炭素数２〜４の直鎖又は分岐アルキレン基、ｍは１〜１０の整数であり、ｍが２以上の場合のＡは同一でも異なっていてもよく、（ＡＯ）_ｍ部分はランダム結合でもブロック結合でもよい；Ｒ^２はイソブチレン及び／又は１，２−ブチレンを必須構成単量体とする炭化水素重合体から水素原子を１つ除いた残基；ｐは０又は１の数；Ｍｎは１，０００以上］
［Ｒ ^７ は水素原子又はメチル基；−Ｘ ^３ −は−Ｏ−又は−ＮＨ−で表される基；Ｒ ^８ は炭素数２〜４の直鎖又は分岐アルキレン基；Ｒ ^９ は炭素数１〜８の直鎖アルキル基；ｒは１の整数である。］
As a result of diligent studies, the present inventors have reached the present invention. That is, the present invention is a (co) polymer containing the monomer (a) represented by the following general formula (1) and the monomer (e) represented by the following general formula (3) as essential constituent monomers. A viscosity index improver containing (A), wherein the ratio Mw / Mn of the weight average molecular weight (Mw) of the (co) polymer (A) to the number average molecular weight (Mn) is 1.6 or less. A certain viscosity index improver.

[R ¹ is a hydrogen atom or a methyl group; -X ^1- is a group represented by -O-, -O (AO) _m- or -NH-, and A is a linear or linear group having 2 to 4 carbon atoms. The branched alkylene group, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different, and the (AO) _m portion may be a random bond or a block bond; R ² is isobutylene and / Or a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing 1,2-butylene as an essential constituent monomer; p is the number of 0 or 1; Mn is 1,000 or more]
[R ⁷ is a hydrogen atom or a methyl group; -X ^3- is a group represented by -O- or -NH-; R ⁸ is a linear or branched alkylene group having 2 to 4 carbon atoms; R ⁹ is a 1 carbon atom. ~ 8 linear alkyl groups; r is an integer of 1. ]

The lubricating oil composition containing the viscosity index improver of the present invention has the effects of excellent shear stability, low HTHS viscosity in the effective temperature range, and excellent viscosity index of the lubricating oil composition.

The viscosity index improver of the present invention is a viscosity index improver containing a copolymer (A) containing the monomer (a) represented by the general formula (1) as an essential constituent monomer, and has a common weight. A lubricating oil composition containing a viscosity index improver having a ratio Mw / Mn of the weight average molecular weight Mw of the coalescence (A) to the number average molecular weight Mn of 1.6 or less, the viscosity index improver, and the base oil. Is.

R ¹ in the general formula (1) is a hydrogen atom or a methyl group. Of these, a methyl group is preferable from the viewpoint of HTHS viscosity in the effective temperature range.

-X ^1- in the general formula (1) is a group represented by -O-, -O (AO) _m- or -NH-.
A 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.
m is an integer of 1 to 10, preferably an integer of 1 to 4, and more preferably an integer of 1 to 2 from the viewpoint of HTHS viscosity in the effective temperature range.
When m is 2 or more, A may be the same or different, and the (AO) _m portion may be a random bond or a block bond.
Of −X ^{1−, the} groups represented by −O− and −O (AO) _m− are preferable from the viewpoint of HTHS viscosity in the effective temperature range, and more preferably −O− and −O ( CH ₂ CH ₂ O)-A group represented by −.

p is a number of 0s or 1s.

R ² in the general formula (1) has one hydrogen atom from a hydrocarbon polymer containing isobutylene and / or 1,2-butylene as an essential constituent monomer (hereinafter, abbreviated as “hydrocarbon polymer”). Residues removed.
Examples of the hydrocarbon polymer include polymers having the following (1) to (3) as constituent monomers in addition to isobutylene and / or 1,2-butylene. The hydrocarbon polymer may be a block polymer or a random polymer. When the hydrocarbon polymer has a double bond, a part or all of the double bond may be hydrogenated by hydrogenation.
(1) Aliphatic unsaturated hydrocarbons [olefins having 2-36 carbon atoms (for example, ethylene, propylene, 2,3-butylene, pentane, heptene, diisoprene, octene, dodecene, octadecene, triacosene, hexatriacene, etc.) and Dienes having 2-36 carbon atoms (for example, butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.)]
(2) Alicyclic unsaturated hydrocarbons [for example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, etylidene bicycloheptene, etc.]
(3) Aromatic group-containing unsaturated hydrocarbons (for example, styrene, α-methylstyrene, vinyltorene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotyl) Styrene, vinylnaphthalene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, etc.) and the like.

Based on the total number of constituent monomers of the hydrocarbon polymer, the total ratio of isobutylene and 1,2-butylene is preferably 30 mol% or more, more preferably from the viewpoint of HTHS viscosity, viscosity index and shear stability. It is 40 mol% or more, particularly preferably 50 mol% or more, and most preferably 60 mol% or more.

Based on the total number of constituent units of the hydrocarbon polymer, the total ratio of isobutylene and 1,2-butylene was calculated by analyzing the hydrocarbon polymer with a 13C-nuclear magnetic resonance spectrum and using the following mathematical formula (1). Can be decided. In the 13C-nuclear magnetic resonance spectrum, the peak derived from the methyl group of isobutylene is an integral value of 30-32 ppm (integral value A), and the branched methylene group of 1,2-butylene (-CH _2- CH (CH ₂ CH ₃ )). A peak derived from −) appears in the integrated value (integrated value B) of 26-27 ppm. It can be obtained from the integrated value of the above peaks and the integrated value (integrated value C) regarding the peak of total carbon of the hydrocarbon polymer.

The monomer (a) represented by the general formula (1) is an ester of a (co) polymer (Y) containing a one-terminal hydroxyl group having a hydroxyl group introduced at one end of a hydrocarbon polymer and (meth) acrylic acid. It can be obtained by a chemical reaction. In addition, "(meth) acrylic" means methacrylic or acrylic.

Specific examples of the one-terminal hydroxyl group-containing (co) polymer (Y) include the following.
An alkylene oxide adduct (Y1); an alkylene oxide (ethylene oxide, propylene oxide, etc.) is added to a (co) polymer obtained by polymerizing an unsaturated hydrocarbon (x) in the presence of an ion polymerization catalyst (sodium catalyst, etc.). Etc. obtained by adding.
Hydroboronized product (Y2); hydroboration reaction product of (co) polymer of (x) having a terminal double bond (for example, those described in US 4,316,973) and the like.
Maleic anhydride-ene-aminoalcohol adduct (Y3); The reaction product obtained by the ene reaction between the (co) polymer of (x) having a terminal double bond and maleic anhydride is imidized with an aminoalcohol. What was obtained.
Hydroformyl-hydride (Y4); the one obtained by hydroformylating the (co) polymer of (x) having a terminal double bond and then hydrogenating it (for example, the one described in JP-A-63-175096). )etc.
Of (Y), (Y1), (Y2) and (Y3) are preferable, and (Y1) is more preferable.

The number average molecular weight (hereinafter abbreviated as Mn) of the monomer (a) is 1,000 or more, preferably 1,000 to 25,000 from the viewpoint of shear stability and HTHS viscosity, and more preferably 1,000 to 25,000. It is 2,000 to 20,000, particularly preferably 2,000 to 15,000, and most preferably 2,500 to 10,000.
The Mn of the monomer (a), the Mn of the (co) polymer (A) described later, and the weight average molecular weight (hereinafter abbreviated as Mw) can be measured by gel permeation chromatography under the following conditions. it can.
<Measuring conditions for Mn of monomer (a) and Mw of (A)>
Equipment: "HLC-802A" [manufactured by Tosoh Corporation]
Column: 2 "TSK gel GMH6" [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C
Sample solution: 0.5 wt% tetrahydrofuran solution Solution injection volume: 200 μl
Detector: Refractive index detector Reference substance: Standard polystyrene (TSKstandardPOLYSTYRENE) 12 points (Molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18, 100, 37, 900, 96, 400, 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

The crystallization temperature of (A) is preferably −40 ° C. or lower, more preferably −50 ° C. or lower, particularly preferably −55 ° C. or lower, and most preferably −60 ° C. from the viewpoint of the low temperature viscosity of the lubricating oil composition. It is as follows.
The crystallization temperature of the (co) copolymer (A) can be measured using a differential scanning calorimeter "Unix (registered trademark) DSC7" (manufactured by PERKIN-ELMER), and 5 mg of (A) can be measured. This is the crystallization temperature observed when the sample is cooled from 100 ° C. to -80 ° C. at an isothermal rate of 10 ° C./min.

When the Mw / Mn of the (co) polymer (A) is 1.6 or less and the (co) polymer has the same Mw and the same SP value, it is preferable from the viewpoint of HTHS viscosity in the effective temperature range. It is 1.5 or less, more preferably 1.4 or less, still more preferably 1.3 or less.

The (co) polymer (A) in the present invention has a monomer (b) represented by the following general formula (2) and a linear alkyl group having 1 to 4 carbon atoms in addition to the monomer (a). From the (meth) acrylic acid alkyl ester (c), the (meth) acrylic acid alkyl ester (d) having a linear alkyl group having 12 to 36 carbon atoms, and the monomer (e) represented by the general formula (3). From the viewpoint of HTHS viscosity at the effective temperature, it is preferable that the copolymer is a constituent monomer containing one or more kinds of monomers selected from the above group.

［Ｒ^３は水素原子又はメチル基；−Ｘ^２−は−Ｏ−又は−ＮＨ−で表される基；Ｒ^４は炭素数２〜４の直鎖又は分岐アルキレン基；Ｒ^５及びＲ^６はそれぞれ独立に炭素数８〜２４の直鎖アルキル基；ｑは０〜２０の整数であり、ｑが２以上の場合のＲ^４は同一でも異なっていてもよく、（Ｒ^４Ｏ）_ｑ部分はランダム結合でもブロック結合でもよい。］

[R ³ is a hydrogen atom or a methyl group; -X ^2- is a group represented by -O- or -NH-; R ⁴ is a linear or branched alkylene group having 2 to ⁴ carbon atoms; R ⁵ and R ⁶ are. A linear alkyl group having 8 to 24 carbon atoms independently; q is an integer of 0 to 20, and R ⁴ when q is 2 or more may be the same or different, and the (R ⁴ O) _q portion is It may be a random join or a block join. ]

R ³ in the general formula (2) is a hydrogen atom or a methyl group. Of these, a methyl group is preferable from the viewpoint of the effect of improving the viscosity index.

-X ^2- in the general formula (2) is a group represented by -O- or -NH-. Of these, the group represented by −O− is preferable from the viewpoint of the effect of improving the viscosity index.

R ⁴ in the general formula (2) is an alkylene group having 2 to 4 carbon atoms. The alkylene group having 2 to 4 carbon atoms includes an ethylene group, an isopropylene group, a 1,2- or 1,3-propylene group, an isobutylene group, and a 1,2-, 1,3- or 1,4-butylene group. Can be mentioned.

Q in the general formula (2) is an integer of 0 to 20, preferably an integer of 0 to 5, and more preferably an integer of 0 to 2 from the viewpoint of the effect of improving the viscosity index.
When q is 2 or more, R ⁴ may be the same or different, and the (R ⁴ O) _q portion may be a random bond or a block bond.

R ⁵ and R ⁶ in the general formula (2) are independently linear alkyl groups having 8 to 24 carbon atoms. Specifically, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-eicosyl group and Examples thereof include an n-tetracosyl group.
Among the linear alkyl groups having 8 to 24 carbon atoms, a linear alkyl group having 8 to 20 carbon atoms is more preferable from the viewpoint of viscosity index, and a linear alkyl group having 8 to 16 carbon atoms is further preferable.

Specific examples of the monomer (b) include 2-octyldecyl (meth) acrylic acid, an ester of ethylene glycol mono-2-octylpentadecyl ether and (meth) acrylic acid, and 2-octyl (meth) acrylic acid. Dodecyl, 2-decyltetradecyl (meth) acrylate, 2-dodecylhexadecyl (meth) acrylate, 2-tetradecyl octadecyl (meth) acrylate, 2-dodecylpentadecyl (meth) acrylate, (meth) acrylic 2-Tetradecyl heptadecyl acid, 2-hexadecyl heptadecyl (meth) acrylate, 2-heptadecyl icosyl (meth) acrylate, 2-hexadecyldocosyl (meth) acrylate, 2 (meth) acrylic acid -Eikosyl docosyl and 2-eicosyl tetracosyl (meth) acrylate can be mentioned.
Among the monomer (b), a (meth) acrylic acid alkyl ester having a branched alkyl group having 18 to 36 carbon atoms is preferable from the viewpoint of viscosity index, and a branched monomer having 18 to 32 carbon atoms is more preferable. A (meth) acrylic acid alkyl ester having an alkyl group, particularly preferably a (meth) acrylic acid alkyl ester having a branched alkyl group having 18 to 28 carbon atoms.

Examples of the (meth) acrylic acid alkyl ester (c) having an alkyl group having 1 to 4 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and butyl (meth) acrylate. And so on.
Of (c), methyl (meth) acrylate and butyl (meth) acrylate are preferable, and butyl (meth) acrylate is particularly preferable.

Examples of the (meth) acrylic acid alkyl ester (d) having a linear alkyl group having 12 to 36 carbon atoms include (meth) acrylic acid n-dodecyl, (meth) acrylic acid n-tridecyl, and (meth) acrylic acid n-. Tetradecyl, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, n-icosyl (meth) acrylate, n-tetracosyl (meth) acrylate, (meth) Examples thereof include n-triacontyl acrylate and n-hexatriacontyl (meth) acrylate.
Of (d), a (meth) acrylic acid alkyl ester having a linear alkyl group having 12 to 32 carbon atoms is preferable, and a (meth) having a linear alkyl group having 12 to 28 carbon atoms is more preferable. Acrylic acid esters, particularly preferred are (meth) acrylic acid esters having a linear alkyl group having 12 to 22 carbon atoms.

［Ｒ^７は水素原子又はメチル基；−Ｘ^３−は−Ｏ−又は−ＮＨ−で表される基；Ｒ^８は炭素数２〜４の直鎖又は分岐アルキレン基；Ｒ^９は炭素数１〜８の直鎖アルキル基；ｒは１〜２０の整数であり、ｒが２以上の場合のＲ^８は同一でも異なっていてもよく、（Ｒ^８Ｏ）_ｒ部分はランダム結合でもブロック結合でもよい。］

[R ⁷ is a hydrogen atom or a methyl group; -X ^3- is a group represented by -O- or -NH-; R ⁸ is a linear or branched alkylene group having 2 to 4 carbon atoms; R ⁹ is a 1 carbon atom. A linear alkyl group of ~ 8; r is an integer of 1 to 20, and when r is 2 or more, R ⁸ may be the same or different, and the (R ⁸ O) _r moiety may be a random bond or a block bond. Good. ]

R ⁷ in the general formula (3) is a hydrogen atom or a methyl group. Of these, a methyl group is preferable from the viewpoint of the effect of improving the viscosity index.

-X ^3- in the general formula (3) is a group represented by -O- or -NH-. Of these, the group represented by −O− is preferable from the viewpoint of the effect of improving the viscosity index.

R ⁸ in the general formula (3) is a linear or branched alkylene group having 2 to 4 carbon atoms. The linear or branched alkylene group having 2 to 4 carbon atoms includes an ethylene group, an isopropylene group, a 1,2- or 1,3-propylene group, an isobutylene group, and 1,2-, 1,3- or 1, A 4-butylene group can be mentioned.

R in the general formula (3) is an integer of 1 to 20, preferably an integer of 1 to 5, and more preferably an integer of 1 to 2 from the viewpoint of the viscosity index improving effect and the low temperature viscosity.
When r is 2 or more, A may be the same or different, and the (R ⁸ O) _r portion may be a random bond or a block bond.

R ⁹ in the general formula (3) is a linear alkyl group having 1 to 8 carbon atoms. Specific examples thereof include methyl group, ethyl group, n-propyl, n-butyl group, n-heptyl group, n-hexyl group, n-pentyl group and n-octyl group.
Among the linear alkyl groups having 1 to 8 carbon atoms, the linear alkyl group having 1 to 6 carbon atoms is preferable from the viewpoint of the viscosity index, and the linear alkyl group having 1 to 5 carbon atoms is particularly preferable. A linear alkyl group having 1 to 4 carbon atoms is preferable, and a linear alkyl group having 2 to 4 carbon atoms is most preferable.

Specific examples of the monomer (e) include methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, methoxyheptyl (meth) acrylate, methoxyhexyl (meth) acrylate, methoxypentyl (meth) acrylate, and methoxyoctyl (meth). Meta) acrylate, ethoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, ethoxybutyl (meth) acrylate, ethoxyheptyl (meth) acrylate, ethoxyhexyl (meth) acrylate, ethoxypentyl (meth) acrylate, ethoxyoctyl (meth) ) Acrylate, proxymethyl (meth) acrylate, proxyethyl (meth) acrylate, proxypropyl (meth) acrylate, proxybutyl (meth) acrylate, proxyheptyl (meth) acrylate, proxyhexyl (meth) acrylate, proxypentyl (meth) Acrylate, Proxyloctyl (meth) acrylate, Butoxymethyl (meth) acrylate, Butoxyethyl (meth) acrylate, Butoxypropyl (meth) acrylate, Butoxybutyl (meth) acrylate, Butoxyheptyl (meth) acrylate, Butoxyhexyl (meth) acrylate , Butoxypentyl (meth) acrylate, butoxyoctyl (meth) acrylate, and alcohol having 1 to 8 carbon atoms plus 2 to 20 mol of alkylene oxides having 2 to 4 carbon atoms (ethylene oxide, propylene oxide, and butylene oxide). And (meth) acrylic acid ester with (meth) acrylic acid and the like.
Among the monomer (e), ethoxyethyl (meth) acrylate and butoxyethyl (meth) acrylate are preferable from the viewpoint of viscosity index.

The (co) polymer (A) in the present invention is, in addition to the monomers (a) to (e), further excluding nitrogen atom-containing monomers (excluding (a), (b) and (e)) (f). ), A copolymer containing one or more selected from the group consisting of a hydroxyl group-containing monomer (g) and a phosphorus atom-containing monomer (h) as a constituent monomer, HTHS in the effective temperature range. Preferred from the viewpoint of viscosity.
Examples of the nitrogen atom-containing monomers (excluding (a), (b) and (e)) (f) include the following monomers (f1) to (f4).

Amide group-containing monomer (f1):
(Meta) acrylamide, monoalkyl (meth) acrylamide [One alkyl group having 1 to 4 carbon atoms bonded to a nitrogen atom; for example, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (Meta) acrylamide and Nn- or isobutyl (meth) acrylamide, etc.], N- (N'-monoalkylaminoalkyl) (meth) acrylamide [One alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom. Those having an aminoalkyl group (2 to 6 carbon atoms); for example, N- (N'-methylaminoethyl) (meth) acrylamide, N- (N'-ethylaminoethyl) (meth) acrylamide, N- (N' -Isopropylamino-n-butyl) (meth) acrylamide and N- (N'-n- or isobutylamino-n-butyl) (meth) acrylamide, etc.], Dialkyl (meth) acrylamide [1 to 4 carbon atoms in the nitrogen atom Two alkyl groups bonded together; for example, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide and N, N-di-n-butyl. (Meta) acrylamide, etc.], N- (N', N'-dialkylaminoalkyl) (meth) acrylamide [Aminoalkyl group (carbon) in which two alkyl groups having 1 to 4 carbon atoms are bonded to the nitrogen atom of the aminoalkyl group. Those having the number 2 to 6); for example, N- (N', N'-dimethylaminoethyl) (meth) acrylamide, N- (N', N'-diethylaminoethyl) (meth) acrylamide, N- (N' , N'-dimethylaminopropyl) (meth) acrylamide and N- (N', N'-di-n-butylaminobutyl) (meth) acrylamide, etc.]; N-vinylcarboxylic acid amide [N-vinylformamide, N -Vinyl acetamide, N-vinyl-n- or isopropionic acid amide, N-vinyl hydroxyacetamide, etc.] and the like.

Nitro group-containing monomer (f2):
4-Nitrostyrene and the like can be mentioned.

1-3-class amino group-containing monomer (f3):
Primary amino group-containing monomer {alkenylamine with 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 monomer {monoalkylaminoalkyl (meth) acrylate [one 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. N-t-Butylaminoethyl (meth) acrylate and N-methylaminoethyl (meth) acrylate, etc.], Dialkenylamine with 6 to 12 carbon atoms [di (meth) allylamine, etc.]}; Body {Dialkylaminoalkyl (meth) acrylate [those having an aminoalkyl group (2-6 carbon atoms) in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom; for example, N, N-dimethylaminoethyl (meth). ) Acrylic and N, N-diethylaminoethyl (meth) acrylate, etc.], alicyclic (meth) acrylate having a nitrogen atom [morpholinoethyl (meth) acrylate, etc.], aromatic monomer [N- (N',) N'-diphenylaminoethyl) (meth) acrylamide, N, N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc.]}, and Examples thereof include these hydrochlorides, sulfates, phosphates, lower alkyl (1 to 8 carbon atoms) monocarboxylic acid (acetic acid, propionic acid, etc.) salts and the like.

Nitrile group-containing monomer (f4):
Examples include (meth) acrylonitrile.

Of (f), (f1) and (f3) are preferable, and N- (N', N'-diphenylaminoethyl) (meth) acrylamide and N- (N', N'are more preferable. -Dimethylaminoethyl) (meth) acrylamide, N- (N', N'-diethylaminoethyl) (meth) acrylamide, N- (N', N'-dimethylaminopropyl) (meth) acrylamide, N, N-dimethyl Aminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate.

Hydroxy group-containing monomer (g):
Hydroxy hydroxyl group-containing aromatic monomers (p-hydroxystyrene, etc.), hydroxyalkyl (2-6 carbon atoms) (meth) acrylate [2-hydroxyethyl (meth) acrylate, and 2- or 3-hydroxypropyl (meth) acrylate Etc.], mono- or bis-hydroxyalkyl (1 to 4 carbon atoms) substituted (meth) acrylamide [N, N-bis (hydroxymethyl) (meth) acrylamide, N, N-bis (hydroxypropyl) (meth) acrylamide , N, N-bis (2-hydroxybutyl) (meth) acrylamide, etc.], vinyl alcohol, alkenol with 3 to 12 carbon atoms [(meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1 -Undecenol, etc.], alkenemonool or alkenediol having 4 to 12 carbon atoms [1-buten-3-ol, 2-butene-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (carbon Numbers 1 to 6) Alkenes (3 to 10 carbon atoms) ethers (2-hydroxyethylpropenyl ethers, etc.), polyvalent (3 to 8 valent) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars, sugars, etc. ) Alkene (3 to 10 carbon atoms) ether or (meth) acrylate [sugar (meth) allyl ether, etc.];
Polyoxyalkylene glycol (2-4 carbon atoms of alkylene group, 2-50 degree of polymerization), polyoxyalkylene polyol [Polyoxyalkylene ether of the above 3-8 valent alcohol (2-4 carbon number of alkylene group, degree of polymerization) 2 to 100)], mono (meth) acrylate of alkyl (carbon number 1 to 4) ether of polyoxyalkylene glycol or polyoxyalkylene polyol [polyethylene glycol (Mn: 100 to 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) acrylic acid Polyoxyethylene (Mn: 150 to 230) sorbitan, etc.] and the like;

Examples of the phosphorus atom-containing monomer (h) include the following monomers (h1) to (h2).

Phosphate ester group-containing monomer (h1):
(Meta) acryloyloxyalkyl (2-4 carbon atoms) phosphate [(meth) acryloyloxyethyl phosphate and (meth) acryloyloxyisopropyl phosphate] and alkenyl phosphate [vinyl phosphate, allyl phosphate, Propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, dodecenyl phosphate, etc.] and the like can be mentioned. In addition, "(meth) acryloyloxy" means acryloyloxy or methacryloyloxy.

Phosphono group-containing monomer (h2):
(Meta) acryloyloxyalkyl (2-4 carbon atoms) phosphonic acid [(meth) acryloyloxyethyl phosphonic acid, etc.] and alkenyl (2-12 carbon atoms) phosphonic acid [vinylphosphonic acid, allylphosphonic acid and octenyl Phosphonate, etc.] and the like.

Of (h), (h1) is preferable, (meth) acryloyloxyalkyl (2-4 carbon atoms) phosphate is more preferable, and (meth) acryloyloxyethyl phosphate is particularly preferable. Is.

The effective temperature of (A) is that it is a copolymer containing the monomer (i) having two or more unsaturated groups in addition to the monomers (a) to (h) as a constituent monomer. It is preferable from the viewpoint of HTHS viscosity in the region.

Examples of the monomer (i) having two or more unsaturated groups include divinylbenzene, alkaziene having 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene and 1,7-). Octadiene, etc.), (di) cyclopentadiene, vinylcyclohexene and etylidenebicycloheptene, limonene, ethylenedi (meth) acrylate, polyalkylene oxide glycol di (meth) acrylate, pentaerythritol triallyl ether, trimethylpropanthry (meth) acrylate , An ester of an unsaturated carboxylic acid having a Mn of 500 or more and a glycol, an ester of an unsaturated alcohol and a carboxylic acid, and the like described in WO01 / 009242.

In (A), in addition to the monomers (a) to (i), the following monomers (j) to (p) may be used as constituent monomers.

Aliphatic hydrocarbon monomer (j):
Examples thereof include alkenes having 2 to 20 carbon atoms (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.).

Alicyclic hydrocarbon monomer (k):
Cyclopentene, cyclohexene, cycloheptene, cyclooctene, pinene and the like can be mentioned.

Aromatic hydrocarbon-based monomer (l):
Styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-chrome Examples thereof include tylbenzene, inden and 2-vinylnaphthalene.

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

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

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

Ester of unsaturated polycarboxylic acid (p):
Alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids [alkyl diesters of unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) with 1 to 8 carbon atoms (dimethyl maleate, dimethyl fumarate, diethyl maleate, etc.) And dioctyl maleate)] and the like.

The proportion of (a) constituting (A) is preferably 1 to 50% by weight, more preferably 5 to 40% by weight, based on the weight of (A) from the viewpoint of HTHS viscosity in the effective temperature range. %, Especially preferably 8-40% by weight, most preferably 10-30% by weight.
The proportion of (b) constituting (A) is preferably 0 to 40% by weight based on the weight of (A) from the viewpoint of the HTHS viscosity in the effective temperature range and the low temperature viscosity of the lubricating oil composition. , More preferably 1 to 30% by weight, and particularly preferably 1 to 25% by weight.
The proportion of (c) constituting (A) is preferably 1 to 80% by weight, more preferably 20 to 70% by weight, based on the weight of (A) from the viewpoint of HTHS viscosity in the effective temperature range. , Particularly preferably 30 to 65% by weight.
The proportion of (d) constituting (A) is preferably 1 to 40% by weight, more preferably 1 to 35% by weight, based on the weight of (A) from the viewpoint of HTHS viscosity in the effective temperature range. %, Especially preferably 2 to 30% by weight.
The proportion of (e) constituting (A) is preferably 0 to 80% by weight, more preferably 5 to 60% by weight, based on the weight of (A) from the viewpoint of HTHS viscosity in the effective temperature range. %, Especially preferably 10 to 35% by weight, most preferably 10 to 30% by weight.
The ratios of (f) to (h) constituting (A) are preferably 0 to 0 based on the weight of (A) from the viewpoint of the HTHS viscosity in the effective temperature range and the low temperature viscosity of the lubricating oil composition. It is 15% by weight, more preferably 1 to 12% by weight, and particularly preferably 2 to 10% by weight.
The proportion of (i) constituting (A) is preferably 0.01 to 200 ppm, more preferably 0.05 to, based on the weight of (A) from the viewpoint of HTHS viscosity in the effective temperature range. It is 50 ppm, particularly preferably 0.1 to 20 ppm.
The proportions of (j) to (p) constituting (A) are preferably 0 to 10% by weight 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. It is more preferably 1 to 7% by weight, and particularly preferably 2 to 5% by weight.

The (co) polymer (A) preferably has a specific solubility parameter (hereinafter abbreviated as SP value) from the viewpoint of solubility in lubricating oil. The SP value of (A) is 7.3 to 9.5 (cal / cm ³ ) ^1/2 , and is preferably 8.5 to 5 from the viewpoint of improving the viscosity index and solubility in the lubricating oil composition. 9.5 (cal / cm ³ ) ^1/2 , more preferably 8.8 to 9.4 (cal / cm ³ ) ^1/2 , particularly preferably 8.9 to 9.3 (cal / cm ³ ) ¹ It is ^{/ 2} .
For the SP value of (A), the SP value of each of the monomers constituting (A) is calculated by the above method, and the SP value of each monomer is based on the mole fraction of the constituent monomer unit. Is the average value.
The SP value of (A) can be reduced to 7.3 to 9.5 (cal / cm ³ ) ^1/2 by appropriately adjusting the SP value and mole fraction of the monomer used.
The SP value in the present invention is a value calculated by the method described in the Fedors method (Polymer Engineering and Science, Utility, 1974, Vol. 14, No. 2 P. 147 to 154).

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 1.6 (cal / cm ³ ) ^{1 /} from the viewpoint of HTHS viscosity and low temperature viscosity in the effective temperature range. It is ² , more preferably 0.6 to 1.4 (cal / cm ³ ) ^1/2 , and particularly preferably 0.7 to 1.1 (cal / cm ³ ) ^1/2 .

The Mw of (A) is preferably 5,000 to 2,000,000 from the viewpoint of HTHS viscosity and low temperature viscosity in the effective temperature range, and a more preferable range varies depending on the use of the lubricating oil composition, and is shown in the table. It is the range described in 1.

* ：オートマチックトランスミッション油
** ：ベルト−コンティニュアスリーバリュアブルトランスミッション油
*** ：マニュアルトランスミッション油

*: Automatic transmission oil
**: Belt-Continuously Valuable Transmission Oil
***: Manual transmission oil

(A) can be obtained by a known atom transfer radical polymerization (ATRP) method, and is described in, for example, WO05 / 087819. Specifically, the above-mentioned monomer is used in a solvent and / or a base oil to form a coordination compound with an atom transfer radical polymerization initiator, a reducing agent, and a transition metal catalyst in an inactive state in at least one oxidizing state. Examples thereof include a method obtained by solution polymerization in the presence of a ligand capable of producing.

Examples of the solvent include toluene, xylene, alkylbenzene having 9 to 10 carbon atoms, methyl ethyl ketone and the like.

The atom transfer radical polymerization initiator that can be used according to the present invention may be any compound having one or more atoms or atomic groups that can be transferred by radicals under polymerization conditions. The atoms or atomic groups that can be transferred by radicals are preferably halogens, more preferably Cl, Br and I. A star polymer can be obtained if there are three or more transferable atoms or atomic groups.

Specific examples of the atomic transfer radical polymerization initiator are propyl-2-bromopropionate, methyl-2-chloropropionate, ethyl-2-chloropropionate, methyl-2-bromopropionate, and ethyl-2. Examples thereof include −bromoisobutyrate, methyl-2-bromoisobutyrate, ethylenebis (2-bromoisobutyrate), 1,1,1-tris (2-bromoisobutyloxymethyl) ethane and the like.

Initiator is generally 10 ^-5 mol / L～3 mol / L range, preferably from 10 ^-4 mol / L～10 range of ² mol / L and particularly preferably 5 - 10 ^-4 mol / • L ^ It is used at concentrations in the range of ^5-10-3 mol / L, but should not be limited by this.

A reducing agent and a transition metal catalyst that is inactive in at least one oxidizing state are used to carry out the polymerization. At that time, the reducing agent can reduce the transition metal catalyst in the inactive state in the oxidized state to a lower active oxidation state, and is involved in the polymerization method with the transition metal catalyst in the lower active oxidation state. Form an oxidation product of the reducing agent. The transition metal catalyst in the active oxidizing state reacts with the atom transfer radical polymerization initiator to produce the transition metal catalyst in the inactive state in which radicals and halide anions are coordinated. The generated radicals may react with the monomer (growth reaction), react with each other (termination reaction), or react with the halide anion (inactivation reaction). Halogen-terminated polymer dormant species can be reactivated by reaction with a transition metal catalyst in an active oxidized state regenerated with a reducing agent.

In this case, advantageous transition metals include Cu, Fe, Co, Cr, Ne, Sm, Mn, Mo, Ag, Zn, Pd, Pt, Re, Rh, Ir, In, Yd and Ru. Metals can be used alone and as a mixture. These metals are expected to catalyze the redox cycle of polymerization, where, for example, the redox pair Cu ⁺ / Cu ²⁺ or Fe ²⁺ / Fe ³⁺ is effective. Correspondingly, the metal compound is added to the reaction mixture as a halide, eg, chloride or bromide, or as an alkoxide. Advantageous metal compounds are CuBr ₂ , CuCl ₂ , CuO, CrCl ₃ , Fe ₂ O ₃ and FeBr ₃ , and a particularly advantageous metal compound is CuBr ₂ .

The metal content of the transition metal catalyst used as the catalyst is less than 500 ppm, preferably less than 200 ppm, more preferably 100 ppm, based on the total weight of the constituent monomers constituting the (co) polymer (A). Is less than.

Reducing agents include ascorbic acid, ascorbic acid ester, organic tin (II) compound, sodium sulfite, low-oxidation sulfur compound, sodium hydrogen sulfite, hydrazine hydrate, acetylacetonate, hydroxyacetone, reduced sugar, monosaccharide, Inorganic salts containing tetrahydrofuran, dihydroanthracene, silane, 2,3-dimethylbutadiene, amines, formamidin sulfinic acid, borane compounds, aldehydes, and metals selected from Fe ²⁺ , Cr ³⁺ , Al ³⁺ , Ti ³⁺ and Ti ^4+. It is an inorganic compound or an organic compound selected from the group consisting of, preferably an organic tin (II) compound such as tin 2-ethylhexanoate.

The polymerization is carried out in the presence of a ligand capable of forming a coordination compound with one or more transition metal catalysts. These ligands are particularly useful for improving the solubility of transition metal compounds. Another important function of the ligand is to avoid the formation of stable organometallic compounds. This is especially important. This is because these stable compounds do not polymerize under selected reaction conditions. In addition, ligands are expected to facilitate the extraction of transmissible atomic groups.

Known ligands can be used and are described, for example, in WO 97/18247 and WO 98/40415.

Preferred ligands include triphenylphosphane, 2,2-bipyridine, alkyl-2,2-bipyridine, such as 4,4-di- (5-nonyl) -2,2-bipyridine, 4,4-di. -(5-Heptyl) -2,2-bipyridine, tris (2-aminoethyl) amine (TREN), tris (2-pyridylmethyl) amine (TPMA), N, N, N', N', N "- Pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine and / or tetramethylethylenediamine, but should not be limited by this. The ligands are used alone or as a mixture. be able to.

These ligands can form a coordination compound with the metal compound in the reaction system, or can be first prepared as a coordination compound and then subsequently added to the reaction mixture.

The ligand-to-transition metal ratio depends on the number of ligand conformations and the number of transition metal conformations. Generally, the molar ratio is in the range of 100: 1 to 0.1: 1, preferably 6: 1 to 0.1: 1, and particularly preferably 3: 1 to 0.5: 1. It should not be limited.

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, or may be a graft copolymer, a block copolymer or a star-type copolymer. ..

The viscosity index improver of the present invention may be a combination of (A) and an alkyl (meth) acrylic acid ester (co) polymer (B) other than (A).
The (B) is not particularly limited as long as it is an alkyl (meth) acrylic acid ester (co) polymer other than (A), but is a (meth) acrylic acid alkyl ester having a linear alkyl group having 1 to 18 carbon atoms. (Co) Polymers and the like can be mentioned.
Specific examples of (B) include n-octadecyl methacrylate / n-dodecyl methacrylate (molar ratio 10 to 30/90 to 70) copolymer and 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) copolymers and the like can be mentioned, 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, more preferably 0, from the viewpoint of low temperature viscosity, based on the weight of (A). It is 0.01 to 20% by weight, particularly preferably 0.01 to 10% by weight.

The lubricating oil composition of the present invention comprises the viscosity index improver and the base oil of the present invention. Base oils include mineral oils (refined solvent oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil by hydrocracking of isoparaffin, naphthenic oil, etc.), synthetic lubricating oil [hydrocarbon synthetic lubricating oil] (Poly α-olefin synthetic lubricating oil, etc.) and ester synthetic lubricating oil, etc.] and mixtures thereof. Of these, mineral oil is preferred.

Kinematic viscosity at 100 ° C. of the base oil (as measured by JIS-K2283) is preferably from the viewpoint of the HTHS viscosity at effective temperature is 1 to 15 mm ² / s, more preferably is 2 to 5 mm ² / s ..
The viscosity index of the base oil (measured by JIS-K2283) is preferably 110 or more from the viewpoint of HTHS viscosity in the effective temperature range.

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

The 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, it is preferable that the base oil having a kinematic viscosity of 4 to 10 mm ² / s at 100 ° C. contains 2 to 10% by weight of (A).
When the lubricating oil composition is used as a gear oil, it is preferable that the base oil having a kinematic viscosity of ² to 10 mm ² / s at 100 ° C. contains (A) in an amount of 3 to 30% by weight.
When the lubricating oil composition is used as an automatic transmission fluid (ATF, belt-CVTF, etc.), 3 to 25% by weight of (A) is added to a base oil having a kinematic viscosity of ² to 6 mm ² / s at 100 ° C. Those containing are preferable.
When the lubricating oil composition is used as a traction oil, it is preferable that the base oil having a kinematic viscosity of 1 to 5 mm ² / s at 100 ° C. contains 0.5 to 10% by weight of (A). ..

The lubricating oil composition of the present invention may contain various additives. Examples of the additive include the following.
(1) Cleaner:
Basic, hyperbasic or neutral metal salts [superbasic or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzenesulfonates, alkylnaphthalensulfonates, etc.)], salicylates, phenates, naphthenates, etc. Classes, carbonates, phosphonates and mixtures thereof;
(2) Dispersant:
Succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates, borates, etc .;
(3) Antioxidant:
Hindered phenols and aromatic secondary amines, etc .;
(4) Oiliness improver:
Long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine, oleylamide, etc.), etc .;
(5) Friction wear conditioner:
Molybdenum-based and zinc-based compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, etc.), etc.;
(6) Extreme pressure agent:
Sulfur-based compounds (mono or disulfide, sulfoxide and sulfur phosphide compounds), phosphofide compounds and chlorinated compounds (chlorinated paraffin, etc.), etc.;
(7) Defoamer:
Silicone oil, metal soap, fatty acid ester, phosphate compound, etc .;
(8) Anti-emulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils, phosphates (polyoxyethylene-containing nonionic surfactants, etc.), etc.;
(9) Corrosion inhibitor:
Nitrogen atom-containing compounds (benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate, etc.) and the like.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

<Manufacturing example 1>
In a reaction vessel equipped with a temperature controller, a vacuum stirring blade, a nitrogen inlet and an outlet, a terminal unsaturated group-containing polybutene (trade name; "Nichiyu Polybutene 10N", manufactured by Nichiyu Co., Ltd., Mn; 1,000) ] 280 parts by weight, tetrahydrofuran-boron / tetrahydrofuran 1 mol / L solution [manufactured by Wako Pure Chemical Industries, Ltd.] 400 parts by weight and 400 parts by weight of tetrahydrofuran were added, and hydroboration was carried out at 25 ° C. for 4 hours, and then water 50. 50 parts by weight, 50 parts by weight of 3N-NaOH aqueous solution and 50 parts by weight of 30 wt% tetrahydrofuran were added to oxidize. The supernatant was recovered by a liquid separation funnel, heated to 50 ° C., and then reduced under reduced pressure at the same temperature. Tetrahydrofuran (0.027 to 0.040 MPa) was removed over 2 hours to obtain a single-ended hydroxyl group-containing polymer (Y2-1).

<Manufacturing example 2>
In a pressure-resistant reaction vessel made of SUS equipped with a temperature controller and a stirrer, 530 parts by weight of a terminal unsaturated group-containing polybutene (trade name: "NOF Polybutene 200N", NOF Corporation, Mn: 2,650] and Maleic anhydride [manufactured by Wako Pure Chemical Industries, Ltd.] 25 parts by weight was added, the temperature was raised to 220 ° C. with stirring, and then an ene reaction was carried out at the same temperature for 4 hours. Then, the mixture was cooled to 25 ° C. and 2-aminoethanol. 20 parts by weight was added, the temperature was raised to 130 ° C. under stirring, and then the imidization reaction was carried out at the same temperature for 4 hours. Unreacted maleic anhydride under reduced pressure (0.027 to 0.040 MPa) at 120 to 130 ° C. The acid and 2-aminoalcohol were removed over 2 hours to obtain a single-ended hydroxyl group-containing polymer (Y3-1).

<Examples 1 to 4, Comparative Example 1>
Base oil A (SP value: 8.3 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C: 4.2 mm ^{2 in} a reaction vessel equipped with a stirrer, heating / cooling device, thermometer and nitrogen introduction tube / S, Viscosity index: 128) 500 parts by weight, 500 parts by weight of the monomer formulation shown in Table 2, 0.03 parts by weight of CuBr ₂ and 0.04 parts by weight of tris (2-pyridylmethyl) amine were added. After performing nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 70 ° C. with stirring under sealing. After raising the temperature, 0.35 g of the atom transfer radical polymerization initiator ethylenebis (2-bromoisobutyrate) and 1.38 parts by weight of the reducing agent tin 2-ethylhexanoate (Neostan U-28, manufactured by Nitto Kasei) were added. The polymerization reaction was carried out for 20 hours. After raising the temperature to 130 ° C., the unreacted monomer is removed under reduced pressure (0.03 MPa) at the same temperature over 2 hours, and the viscosity index containing the copolymers (A1) to (A4) and (H1) is contained. Improvers (R1) to (R4) and (S1) were obtained. The SP values of the obtained copolymers (A1) to (A4) and (H1) were calculated by the above method, and Mn and Mw were measured by the above method. In addition, the base oil solubility of the copolymer was evaluated by the following method. The results are shown in Table 2.

<Examples 5 to 9, Comparative Example 2>
Same as the method of Example 1 except that 0.19 parts by weight of methyl-2-bromoisobutyrate was used instead of 0.35 parts by weight of ethylenebis (2-bromoisobutyrate) as the atom transfer radical polymerization initiator. Then, the viscosity index improvers (R5) to (R9) and (S2) containing the copolymers (A5) to (A9) and (H2) were obtained. The SP values of the obtained copolymers (A5) to (A9) and (H2) were calculated by the above method, and Mn and Mw were measured by the above method. In addition, the base oil solubility of the copolymer was evaluated by the following method. The results are shown in Table 2.

<Examples 10 to 12, Comparative Example 3>
Except that 0.56 parts by weight of 1,1,1-tris (2-bromoisobutyloxymethyl) ethane was used instead of 0.35 parts by weight of ethylenebis (2-bromoisobutyrate) as an atom transfer radical polymerization initiator. Viscosity index improvers (R10) to (R12) and (S3) containing copolymers (A10) to (A12) and (H3) were obtained in the same manner as in the method of Example 1. The SP values of the obtained copolymers (A10) to (A12) and (H3) were calculated by the above method, and Mn and Mw were measured by the above method. In addition, the base oil solubility of the copolymer was evaluated by the following method. The results are shown in Table 2.

<Comparative Examples 4-9>
Base oil A (SP value: 8.3 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C.: 4.2 mm ^{2 in} a reaction vessel equipped with a stirrer, heating / cooling device, thermometer and nitrogen introduction tube. / S, Viscosity index: 128) 500 g, 500 parts by weight of the monomer formulation shown in Table 2, 2,2'-azobis (2,4-dimethylvaleronitrile) 2.50 parts by weight and 2,2'- After adding 1.50 parts by weight of azobis (2-methylbutyronitrile) and performing nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76 ° C. with stirring under sealing, and the temperature was the same for 4 hours. A polymerization reaction was carried out. After raising the temperature to 130 ° C., the unreacted monomer under reduced pressure (0.03 MPa) at the same temperature is removed over 2 hours, and the viscosity index improver (S4) containing the copolymers (H4) to (H9) is contained. )-(S9) were obtained. The SP values of the obtained copolymers (H4) to (H9) were calculated by the above method, and Mn and Mw were measured by the above method. In addition, the base oil solubility of the copolymer was evaluated by the following method. The results are shown in Table 2.

<Evaluation method of base oil solubility of copolymer>
The appearances of the viscosity index improvers (R1) to (R12) and (S1) to (S9) were visually observed, and the base oil solubility was evaluated according to the following evaluation criteria.
[Evaluation criteria]
◯: Uniform appearance, no insoluble material of copolymer ×: Non-uniform appearance, insoluble material of copolymer is observed

The compositions of the monomers (a) to (h) shown in Table 2 are as described below.
(Y1-1): One-terminal hydroxyl group-containing polymer of hydrogenated polybutadiene (trade name: KrasolHLBH-5000M, manufactured by Cray Valley, 1,2-butylene ratio: 65 mol%, hydroxyl value: 10.4 mgKOH / g, Mn: 6000)
(Y2-1): Hydroboronized product of one-ended unsaturated group-containing polybutene of Production Example 1 (Mn: 1200)
(Y3-1): Maleic anhydride-ene-aminoalcohol adduct of one-terminal unsaturated group-containing polybutene of Production Example 2 (Mn: 2700)
(A1-1): Methacrylic acid esterified product of (Y1-1) (a1-2): Methacrylic acid esterified product of (Y2-1) (a1-3): Methacrylic acid esterified product of (Y3-1) (b) -1): 2-n-decyltetradecyl methacrylate (b-2): 2-n-dodecylhexadecyl methacrylate (c-1): methyl methacrylate (c-2): butyl methacrylate (d-1) ): N-Dodecyl methacrylate (d-2): n-tetradecyl methacrylate (d-3): n-hexadecyl methacrylate (e-1): ethoxyethyl methacrylate (e-2): butoxyethyl methacrylate (e-2) f-1): N, N-dimethylaminoethyl methacrylate (g-1): hydroxyethyl methacrylate (h-1): methacrylicyloxyethyl phosphate

<Examples 13 to 24, Comparative Examples 10 to 18>
Base oil A (SP value: 8.3 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C.: 4.2 mm ² / s, viscosity index: 128) is put into a stainless steel container equipped with a stirrer. Then, the viscosity index improvers (R1) to (R12) and (S1) to so that the HTHS viscosity at 150 ° C. of the obtained lubricating oil composition is 2.60 ± 0.05 (mm ² / s), respectively. (S9) was added to obtain lubricating oil compositions (V1) to (V12) and (W1) to (W9).
The shear stability, HTHS viscosity (100 ° C.), and viscosity index of the lubricating oil compositions (V1) to (V12) and (W1) to (W9) were measured by the following methods. The results are shown in Table 3.

<Measurement method and calculation method of shear stability of lubricating oil composition>
It was measured by the method of ASTM D 6278 and calculated by the method of ASTM D 6022.

<Measuring method of HTHS viscosity of lubricating oil composition>
Measured at 100 ° C. by the method of ASTM D 5484.

<Calculation method of viscosity index of lubricating oil composition>
The kinematic viscosities at 40 ° C. and 100 ° C. were measured by the method of ASTM D 445 and calculated by the method of ASTM D 2270.

As is clear from the results in Table 3, the lubricating oil composition (Examples 13 to 24) containing the viscosity index improver of the present invention has excellent shear stability and a low HTHS viscosity in the effective temperature range. It can be seen that the viscosity index is high and excellent. On the other hand, it can be seen that the lubricating oil compositions of Comparative Examples 10 to 18 are inferior in at least one of the shear stability, the HTHS viscosity in the effective temperature range, and the viscosity index.

The lubricating oil composition containing the viscosity index improver of the present invention includes a drive system lubricating oil (MTF, differential gear oil, ATF, belt-CVTF, etc.), a hydraulic oil (machine hydraulic oil, power steering oil and shock). It is suitable as absorber oil, etc.), engine oil (for gasoline and diesel, etc.) and traction oil.

Claims (10)

Contains a (co) polymer (A) containing the monomer (a) represented by the following general formula (1) and the monomer (e) represented by the following general formula (3) as essential constituent monomers. A viscosity index improver having a ratio Mw / Mn of the weight average molecular weight (Mw) of the (co) polymer (A) to the number average molecular weight (Mn) of 1.6 or less. ..

[R ¹ is a hydrogen atom or a methyl group; -X ^1- is a group represented by -O-, -O (AO) _m- or -NH-, and A is a linear or linear group having 2 to 4 carbon atoms. The branched alkylene group, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different, and the (AO) _m portion may be a random bond or a block bond; R ² is isobutylene and / Or a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing 1,2-butylene as an essential constituent monomer; p is the number of 0 or 1; Mn is 1,000 or more]

[R ⁷ is a hydrogen atom or a methyl group; -X ^3- is a group represented by -O- or -NH-; R ⁸ is a linear or branched alkylene group having 2 to 4 carbon atoms; R ⁹ is a 1 carbon atom. ~ 8 linear alkyl groups; r is an integer of 1. ] R ² in the general formula (1) is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing isobutylene and / or 1,2-butylene as an essential constituent monomer, and the hydrocarbon polymer. The residue according to claim 1, wherein one hydrogen atom is removed from the hydrocarbon polymer in which the total ratio of isobutylene and 1,2-butylene is 30 mol% or more based on the total number of constituent monomers of the above. Viscous index improver. The viscosity index improvement according to claim 1 or 2, wherein (A) is a (co) polymer containing 1 to 50% by weight of (a) based on the weight of (A) as a constituent monomer. Agent. (A) is a (meth) acrylic acid alkyl ester having a monomer (b) represented by the following general formula (2) as a constituent monomer of (A) and a linear alkyl group having 1 to 4 carbon atoms. It is a copolymer comprising one or more monomers selected from (c) and having a linear alkyl group having 12 to 36 carbon atoms (meth) acrylic acid alkyl ester (d) or Ranaru group The viscosity index improver according to any one of claims 1 to 3.

[R ³ is a hydrogen atom or a methyl group; -X ^2- is a group represented by -O- or -NH-; R ⁴ is a linear or branched alkylene group having 2 to ⁴ carbon atoms; R ⁵ and R ⁶ are. A linear alkyl group having 8 to 24 carbon atoms independently; q is an integer of 0 to 20, and R ⁴ when q is 2 or more may be the same or different, and the (R ⁴ O) _q portion is It may be a random join or a block join. ] (A) is further derived from the nitrogen atom-containing monomer (excluding (a), (b) and (e)) (f), the hydroxyl group-containing monomer (g) and the phosphorus atom-containing monomer (h). The viscosity index improver according to any one of claims 1 to 4, which is a copolymer containing one or more monomers selected from the above group as constituent monomers. The viscosity index improver according to any one of claims 1 to 5, wherein the weight average molecular weight of (A) is 5,000 to 2,000,000. A lubricating oil composition containing the viscosity index improver and the base oil according to any one of claims 1 to 6. Furthermore, it contains one or more additives selected from the group consisting of detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, anti-emulsifiers and corrosion inhibitors. The lubricating oil composition according to claim 7. The lubricating oil composition according to claim 7 or 8, wherein the base oil has a kinematic viscosity at 100 ° C. of 1 to 15 mm ² / s and the viscosity index of the base oil is 110 or more. The method for producing a viscosity index improver according to any one of claims 1 to 6, which uses the atom transfer radical polymerization (ATRP) method.