JP2013203849A - Viscosity index improver composition and lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viscosity index improver composition (R) and a lubricating oil composition which has a viscosity index improving effect, and excellent fuel consumption property.SOLUTION: A viscosity index improver composition (R) which contains monomer (a) expressed by general formula (1) as an indispensable composition monomer, and which contains (co-)polymer (A) in which a solubility parameter is 7.3 to 11 (cal/cm), and ester-based lubricant base oil (S) whose kinematic viscosity at 100°C is 1 to 30 mm/s; a lubricating oil composition that contains the (R) and the base oil; and (co-)polymer (A) in which the solubility parameter is 7.3 to 11 (cal/cm)by polymerizing the monomer containing the (a) in the presence of the (S), are obtained, by a method for manufacturing the viscosity index improver composition (R) including the (co-)polymer (A) and the lubricant base oil (S).

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 for automobiles and the like generally decrease in viscosity as the temperature increases, but from the viewpoint of fuel economy, the viscosity is required not to change as much as possible over a wide range from room temperature to 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) and an olefin copolymer (Patent Document 4) are known.

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 composition and a lubricating oil composition that have a high viscosity index improving effect and excellent fuel economy.

Ｒ^１は水素原子又はメチル基；Ｘは炭素数２〜４のアルキレン基；ｎは０〜２０の数
であり、ｎが２以上の場合のＸは同一でも異なっていてもよく、（ＸＯ）ｎ部分はランダム結合でもブロック結合でもよい；Ｒ^２は一般式（２）、一般式（３）又は一般式（４）で表される炭素数４〜１３の分岐アルキル基である。

Ｒ^３及びＲ^４は、それぞれ独立に炭素数１〜１１の直鎖又は分岐アルキル基；Ｒ^５は水素原子又は炭素数１〜１０の直鎖若しくは分岐アルキル基であり、Ｒ^３〜Ｒ^５の合計炭素数が３〜１２である。

Ｒ^６及びＲ^７は、それぞれ独立に水素原子又は炭素数１〜８の直鎖若しくは分岐アルキル基；Ｒ^８、Ｒ^９及びＲ¹⁰は、それぞれ独立に炭素数１〜９の直鎖又は分岐アルキル基であり、Ｒ^６〜Ｒ¹⁰の合計炭素数が３〜１１である。

Ｒ¹¹、Ｒ¹²及びＲ¹³は、それぞれ独立に炭素数１〜８の直鎖又は分岐アルキル基であり、Ｒ¹¹〜Ｒ¹³の合計炭素数が３〜１０である。 As a result of intensive studies, the present inventors have arrived at the present invention. That is, in the present invention, the monomer (a) represented by the following general formula (1) is an essential constituent monomer, and the solubility parameter is 7.3 to 11 (cal / cm ³ ) ^1/2 . Viscosity index improver composition (R) comprising (co) polymer (A) and ester-based lubricating base oil (S) having a kinematic viscosity at 100 ° C. of 1 to 30 mm ² / s, R) and a lubricating oil composition containing a base oil, and a monomer containing (a) in the presence of (S) are polymerized to give a solubility parameter of 7.3 to 11 (cal / Cm ³ ) ^1/2 (co) polymer (A), characterized in that (A) and (S), a method for producing a viscosity index improver composition (R) comprising (S), It is.

R ¹ is a hydrogen atom or a methyl group; X is an alkylene group having 2 to 4 carbon atoms; n is a number from 0 to 20, and when n is 2 or more, X may be the same or different, and (XO) The n moiety may be a random bond or a block bond; R ² is a branched alkyl group having 4 to 13 carbon atoms represented by the general formula (2), the general formula (3), or the general formula (4).

R ³ and R ⁴ are each independently a linear or branched alkyl group having 1 to 11 carbon atoms; R ⁵ is a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, and R ^{3 to} R ⁵ The total carbon number is 3-12.

R ⁶ and R ⁷ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms; R ⁸ , R ⁹ and R ¹⁰ are each independently a linear or branched alkyl group having 1 to 9 carbon atoms; a ^group, the total number of carbon atoms of R 6 to R ¹⁰ is 3-11.

R ¹¹ , R ¹² and R ¹³ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms, and the total carbon number of R ^{11 to} R ¹³ is 3 to 10.

  The lubricating oil composition comprising the viscosity index improver composition (R) of the present invention has a high viscosity index improving effect, excellent fuel economy, and is difficult to increase the low temperature viscosity of the lubricating oil composition. Play.

  The viscosity index improver composition (R) of the present invention comprises a (co) polymer (A) having 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.

  X in General formula (1) is a C2-C4 alkylene group. Examples of the alkylene group having 2 to 4 carbon atoms include ethylene group, 1,2- or 1,3-propylene group, 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.

  In the general formula (1), n 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.

  X in the general formula (1) when n is 2 or more may be the same or different, and the (XO) n moiety may be a random bond or a block bond.

R ² is a branched alkyl group having 4 to 13 carbon atoms represented by the following general formula (2), general formula (3), or general formula (4).

一般式（２）におけるＲ^３及びＲ^４は、それぞれ独立に炭素数１〜１１の直鎖又は分岐アルキル基である。
炭素数１〜１１の直鎖又は分岐アルキル基としては、炭素数１〜１１の直鎖アルキル基及び炭素数３〜１１の分岐アルキル基が挙げられる。
炭素数１〜１１の直鎖アルキル基としては、メチル基、エチル基、ｎ−プロピル基、ｎ
−ブチル基、ｎ−ペンチル基、ｎ−へキシル基、ｎ−ヘプチル基、ｎ−オクチル基、ｎ−ノニル基、ｎ−デシル基及びｎ−ウンデシル基が挙げられる。
炭素数３〜１１の分岐アルキル基としては、イソプロピル基、イソブチル基、ｔ−ブチ
ル基、イソペンチル基、ネオペンチル基、イソヘキシル基、イソオクチル基、２−エチルヘキシル基、イソノニル基、３，５，５−トリメチルヘキシル基、２，４，６−トリメチルヘプチル基、２−メチル−ｎ−ノニル基、イソデシル基、２−メチル−ｎ−デシル基、２−エチル−ｎ−ノニル基及びイソウンデシル基等が挙げられる。
一般式（２）におけるＲ^５は、水素原子又は炭素数１〜１０の直鎖若しくは分岐アルキル基である。
炭素数１〜１０の直鎖又は分岐アルキル基としては、炭素数１〜１０の直鎖アルキル基及び炭素数３〜１０の分岐アルキル基が挙げられる。
炭素数１〜１０の直鎖アルキル基としては、Ｒ^３及びＲ^４として例示した炭素数１〜１１の直鎖アルキル基のうち、炭素数１〜１０の直鎖アルキル基として例示したものと同様のものが挙げられる。
炭素数３〜１０の分岐アルキル基としては、Ｒ^３及びＲ^４として例示した炭素数３〜１
１の分岐アルキル基のうち、炭素数３〜１０の分岐アルキル基として例示したものと同様のものが挙げられる。
一般式（２）におけるＲ^３〜Ｒ^５の合計炭素数は３〜１２であり、低温粘度の観点から好ましくは４〜１２、更に好ましくは５〜１２である。

R ³ and R ⁴ in the general formula (2) are each independently a linear or branched alkyl group having 1 to 11 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 11 carbon atoms include a linear alkyl group having 1 to 11 carbon atoms and a branched alkyl group having 3 to 11 carbon atoms.
Examples of the linear alkyl group having 1 to 11 carbon atoms include methyl group, ethyl group, n-propyl group, n
Examples include -butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group and n-undecyl group.
Examples of the branched alkyl group having 3 to 11 carbon atoms include isopropyl group, isobutyl group, t-butyl group, isopentyl group, neopentyl group, isohexyl group, isooctyl group, 2-ethylhexyl group, isononyl group, 3,5,5-trimethyl. Examples include a hexyl group, 2,4,6-trimethylheptyl group, 2-methyl-n-nonyl group, isodecyl group, 2-methyl-n-decyl group, 2-ethyl-n-nonyl group, and isoundecyl group.
R ⁵ in the general formula (2) is a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 10 carbon atoms include a linear alkyl group having 1 to 10 carbon atoms and a branched alkyl group having 3 to 10 carbon atoms.
Examples of the straight-chain alkyl group having 1 to 10 carbon atoms, among the exemplified straight chain alkyl group having 1 to 11 carbon atoms as R ³ and R ^4, similar to those exemplified as the linear alkyl group having 1 to 10 carbon atoms Can be mentioned.
Examples of the branched alkyl group having 3 to 10 carbon atoms include ³ to 1 carbon atoms exemplified as R ³ and R ^4.
Among the branched alkyl groups of 1, the same as those exemplified as the branched alkyl group having 3 to 10 carbon atoms can be mentioned.
The total carbon number of R ^{3 to} R ⁵ in the general formula (2) is 3 to 12, preferably 4 to 12 and more preferably 5 to 12 from the viewpoint of low temperature viscosity.

一般式（３）におけるＲ^６及びＲ^７は、それぞれ独立に水素原子又は炭素数１〜８の直鎖若しくは分岐アルキル基である。
炭素数１〜８の直鎖又は分岐アルキル基としては、炭素数１〜８の直鎖アルキル基及び炭素数３〜８の分岐アルキル基が挙げられる。
炭素数１〜８の直鎖アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数１〜１１の直鎖アルキル基のうち、炭素数１〜８の直鎖アルキル基として例示したものと同様のものが挙げられる。
炭素数３〜８の分岐アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数３〜１１の分岐アルキル基のうち、炭素数３〜８の分岐アルキル基として例示したものと同様のものが挙げられる。
一般式（３）におけるＲ^８、Ｒ^９及びＲ¹⁰は、それぞれ独立に炭素数１〜９の直鎖又は分岐アルキル基である。
炭素数１〜９の直鎖又は分岐アルキル基としては、炭素数１〜９の直鎖アルキル基及び炭素数３〜９の分岐アルキル基が挙げられる。
炭素数１〜９の直鎖アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数１〜１１の直鎖アルキル基のうち、炭素数１〜９の直鎖アルキル基として例示したものと同様のものが挙げられる。
炭素数３〜９の分岐アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数３〜１１の分岐アルキル基のうち、炭素数３〜９の分岐アルキル基として例示したものと同様のものが挙げられる。
一般式（３）におけるＲ^６〜Ｒ¹⁰の合計炭素数は３〜１１であり、低温粘度の観点から好ましくは４〜１１、更に好ましくは５〜１１である。

R ⁶ and R ⁷ in the general formula (3) are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 8 carbon atoms include a linear alkyl group having 1 to 8 carbon atoms and a branched alkyl group having 3 to 8 carbon atoms.
As a C1-C8 linear alkyl group, it is a C1-C8 linear alkyl group among the C1-C11 linear alkyl groups illustrated as R < ³ > and R < ⁴ > in General formula (2). The thing similar to what was illustrated as is mentioned.
The branched alkyl group having 3 to 8 carbon atoms, the general formula (2) Among the exemplified branched alkyl group having a carbon number of 3 to 11 as R ³ and R ⁴ in, exemplified as branched alkyl group having 3 to 8 carbon atoms The thing similar to a thing is mentioned.
R ⁸ , R ⁹ and R ¹⁰ in the general formula (3) are each independently a linear or branched alkyl group having 1 to 9 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 9 carbon atoms include a linear alkyl group having 1 to 9 carbon atoms and a branched alkyl group having 3 to 9 carbon atoms.
As a C1-C9 linear alkyl group, C1-C9 linear alkyl group among the C1-C11 linear alkyl groups illustrated as R < ³ > and R < ⁴ > in General formula (2). The thing similar to what was illustrated as is mentioned.
The branched alkyl group of 3-9 carbon atoms, the general formula (2) Among the exemplified branched alkyl group having a carbon number of 3 to 11 as R ³ and R ⁴ in, exemplified as branched alkyl group having 3 to 9 carbon atoms The thing similar to a thing is mentioned.
The total carbon number of R ^{6 to} R ¹⁰ in the general formula (3) is 3 to 11, preferably 4 to 11 and more preferably 5 to 11 from the viewpoint of low temperature viscosity.

一般式（４）におけるＲ¹¹、Ｒ¹²及びＲ¹³は、それぞれ独立に炭素数１〜８の直鎖又は分岐アルキル基である。
炭素数１〜８の直鎖又は分岐アルキル基としては、炭素数１〜８の直鎖アルキル基及び炭素数３〜８の分岐アルキル基が挙げられる。
炭素数１〜８の直鎖アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数１〜１１の直鎖アルキル基のうち、炭素数１〜８の直鎖アルキル基として例示したものと同様のものが挙げられる。
炭素数３〜８の分岐アルキル基としては、一般式（２）におけるＲ^３及びＲ^４として例示した炭素数３〜１１の分岐アルキル基のうち、炭素数３〜８の分岐アルキル基として例示したものと同様のものが挙げられる。
一般式（４）におけるＲ¹¹〜Ｒ¹³の合計炭素数は３〜１０であり、低温粘度の観点から好ましくは４〜１０、更に好ましくは５〜１０である。

R ¹¹ , R ¹² and R ¹³ in the general formula (4) are each independently a linear or branched alkyl group having 1 to 8 carbon atoms.
Examples of the linear or branched alkyl group having 1 to 8 carbon atoms include a linear alkyl group having 1 to 8 carbon atoms and a branched alkyl group having 3 to 8 carbon atoms.
As a C1-C8 linear alkyl group, it is a C1-C8 linear alkyl group among the C1-C11 linear alkyl groups illustrated as R < ³ > and R < ⁴ > in General formula (2). The thing similar to what was illustrated as is mentioned.
The branched alkyl group having 3 to 8 carbon atoms, the general formula (2) Among the exemplified branched alkyl group having a carbon number of 3 to 11 as R ³ and R ⁴ in, exemplified as branched alkyl group having 3 to 8 carbon atoms The thing similar to a thing is mentioned.
The total carbon number of R ^{11 to} R ¹³ in the general formula (4) is 3 to 10, preferably 4 to 10 and more preferably 5 to 10 from the viewpoint of low temperature viscosity.

Specific examples of R ² in the general formula (1) include 1,1-diisopropylmethyl group, 1,1-di (sec-butyl) methyl group, 1,1-di (t-butyl) methyl group, 1, 1-dineopentylmethyl group, 1,1-dimethyl-n-propyl group, 1,5-dimethyl-n-hexyl group, 1-methyl-1-n-propyl-n-hexyl group, 1,1-di -N-pentylethyl group, 1,4-dimethyl-1-ethyl-n-pentyl group, 1-isobutyl-1-methyl-n-hexyl group, 1- (1'-methylpropyl) -2-methyl-n -Pentyl group, 1,5-trimethyl-n-heptyl group, 1,1-diethyl-5-methyl-n-hexyl group, 1-methyl-1-n-propyl-n-octyl group, 4-ethyl-1 -Methyl-n-hexyl group, 1,2,2-trimethyl-n Hexyl group, 1,2,2-trimethyl-n-decyl group, 1,2,2,5-tetramethyl-n-hexyl group, 1,2,2,3,5-pentamethyl-n-heptyl group, 1 , 2,2,5,5-pentamethyl-n-hexyl group, 1-ethyl-1,4-dimethyl-n-hexyl group, 1-ethyl-2,2-dimethyl-n-nonyl group, 1,2- Diethyl-2-methyl-n-octyl group, 1-isopropyl-2,2-dimethyl-n-octyl group, 1-methyl-2,2-diisopropyl-n-pentyl group, 2,2-dimethyl-n-butyl Group, 2,2-dimethyl-n-heptyl group, 2,2-dimethyl-n-undecyl group, 2,2,3-trimethyl-n-pentyl group, 2,2,4-trimethyl-n-pentyl group, 2,2,5-trimethyl-n-hexyl group, 2,2 7-trimethyl-n-decyl group, 2,2,9-trimethyl-n-decyl group, 2,2,4,5-tetramethyl-n-hexyl group, 2,2-diethyl-n-pentyl group, 2 , 2-diethyl-n-nonyl group, 2-ethyl-2-methyl-n-hexyl group, 2-ethyl-2-methyl-n-decyl group, 2-ethyl-2-propyl-n-hexyl group, 2 -Isopropyl-2-methyl-n-heptyl group, 2-isopropyl-2-methyl-n-nonyl group, 2,2-diisopropyl-n-hexyl group, 1,1,2,2-tetramethyl-n-hexyl Group, 1,1,2,2-tetramethyl-n-nonyl group, 1,2-diethyl-1,2-dimethyl-n-butyl group, 1,2-diethyl-1,2-dimethyl-n-pentyl Group 1,2,2-diethyl-1-methyl-n-penty Group, 1,2,2-diethyl-1-methyl-n-hexyl group, 1-isopropyl-1,2,2-trimethyl-n-hexyl group, 2-isopropyl-1,1,2-trimethyl-n -Hexyl group, 1-isobutyl-1,2,2-trimethyl-n-hexyl group, 3,3-dimethyl-n-butyl group, 3,3-dimethyl-n-hexyl group, 3,3-dimethyl-n -Octyl group, 3,3-dimethyl-n-undecyl group, 3,3-diethyl-n-hexyl group, 3,3-diethyl-n-octyl group, 3-ethyl-3-methyl-n-hexyl group, 3-ethyl-3-methyl-n-octyl group, 3,3-diisopropyl-n-pentyl group, 3,3-diisopropyl-4-methyl-n-pentyl group, 3,3-diisopropyl-n-hexyl group, 3-methyl-3-isop Pills -n- pentyl, 3-methyl-3-isopropyl -n- octyl and 3-methyl -3-t-butyl -n- heptyl group.
Among these, a branched alkyl group having 4 to 13 carbon atoms is preferable from the viewpoint of the effect of improving the viscosity index and the low-temperature viscosity, a branched alkyl group having 5 to 12 carbon atoms is more preferable, and a carbon number is particularly preferable. 6 to 10 branched alkyl groups.

Specific examples of the monomer (a) include 1,1-diisopropylmethyl (meth) acrylate, 1,1-di (sec-butyl) methyl (meth) acrylate, and 1,1-di (t-butyl) methyl. (Meth) acrylate, 1,1-dineopentylmethyl (meth) acrylate, 1,1-dimethyl-n-propyl (meth) acrylate, 1,5-dimethyl-n-hexyl (meth) acrylate, 1-methyl- 1-n-propylhexyl (meth) acrylate, 1,1-di-n-pentylethyl (meth) acrylate, 1,4-dimethyl-1-ethyl-n-pentyl (meth) acrylate, 1-isobutyl-1- Methyl-n-hexyl (meth) acrylate, 1- (1′-methyl-n-propyl) -2-methyl-n-pentyl (meth) acrylate, 1,1, 5-trimethyl-n-heptyl (meth) acrylate, 1,1-diethyl-5-methyl-n-hexyl (meth) acrylate, 1-methyl-1-n-propyl-n-octyl (meth) acrylate, 4- Ethyl-1-methyl-n-hexyl (meth) acrylate, 1,2,2-trimethyl-n-hexyl (meth) acrylate, 1,2,2-trimethyl-n-decyl (meth) acrylate, 1,2, 2,5-tetramethyl-n-hexyl (meth) acrylate, 1,2,2,3,5-pentamethyl-n-heptyl (meth) acrylate, 1,2,2,5,5-pentamethyl-n-hexyl (Meth) acrylate, 1-ethyl-1,4-dimethyl-n-hexyl (meth) acrylate, 1-ethyl-2,2-dimethyl-n-nonyl (meth) acrylate Rate, 1,2-diethyl-2-methyl-n-octyl (meth) acrylate, 1-isopropyl-2,2-dimethyl-n-octyl (meth) acrylate, 1-methyl-2,2-diisopropyl-n- Pentyl (meth) acrylate, 2,2-dimethyl-n-butyl (meth) acrylate, 2,2-dimethyl-n-heptyl (meth) acrylate, 2,2-dimethyl-n-undecyl (meth) acrylate, 2, 2,3-trimethyl-n-pentyl (meth) acrylate, 2,2,4-trimethyl-n-pentyl (meth) acrylate, 2,2,5-trimethyl-n-hexyl (meth) acrylate, 2,2, 7-trimethyl-n-decyl (meth) acrylate, 2,2,9-trimethyl-n-decyl (meth) acrylate, 2,2,4 5-tetramethyl-n-hexyl (meth) acrylate, 2,2-diethyl-n-pentyl (meth) acrylate, 2,2-diethyl-n-nonyl (meth) acrylate, 2-ethyl-2-methyl-n -Hexyl (meth) acrylate, 2-ethyl-2-methyl-n-decyl (meth) acrylate, 2-ethyl-2-n-propylhexyl (meth) acrylate, 2-isopropyl-2-methyl-n-heptyl ( (Meth) acrylate, 2-isopropyl-2-methyl-n-nonyl (meth) acrylate, 2,2-diisopropyl-n-hexyl (meth) acrylate, 1,1,2,2-tetramethyl-n-hexyl (meth) ) Acrylate, 1,1,2,2-tetramethyl-n-nonyl (meth) acrylate, 1,2-diethyl-1,2-dimethyl Til-n-butyl (meth) acrylate, 1,2-diethyl-1,2-dimethyl-n-pentyl (meth) acrylate, 1,2,2-diethyl-1-methyl-n-pentyl (meth) acrylate, 1,2,2-diethyl-1-methyl-n-hexyl (meth) acrylate, 1-isopropyl-1,2,2-trimethyl-n-hexyl (meth) acrylate, 2-isopropyl-1,1,2- Trimethyl-n-hexyl (meth) acrylate, 1-isobutyl-1,2,2-trimethyl-n-hexyl (meth) acrylate, 3,3-dimethyl-n-butyl (meth) acrylate, 3,3-dimethyl- n-hexyl (meth) acrylate, 3,3-dimethyl-n-octyl (meth) acrylate, 3,3-dimethyl-n-undecyl (meth) a Relate, 3,3-diethyl-n-hexyl (meth) acrylate, 3,3-diethyl-n-octyl (meth) acrylate, 3-ethyl-3-methyl-n-hexyl (meth) acrylate, 3-ethyl- 3-methyl-n-octyl (meth) acrylate, 3,3-diisopropyl-n-pentyl (meth) acrylate, 3,3-diisopropyl-4-methyl-n-pentyl (meth) acrylate, 3,3-diisopropyl- n-hexyl (meth) acrylate, 3-methyl-3-isopropyl-n-pentyl (meth) acrylate, 3-methyl-3-isopropyl-n-octyl (meth) acrylate, 3-methyl-3-t-butyl- Examples include n-heptyl (meth) acrylate. These may be used alone or in combination of two or more.
Among (a), 1- (1′-methyl-n-propyl) -2-methyl-n-pentyl (meth) acrylate and 1-isobutyl-1 are preferable from the viewpoint of the effect of improving the viscosity index and low temperature viscosity. -Methyl-n-hexyl (meth) acrylate, 2-ethyl-2-n-propyl-n-hexyl (meth) acrylate and 1,1,5-trimethyl-n-heptyl (meth) acrylate. In addition, (meth) acrylate means an acrylate or a methacrylate.

(A) is a copolymer having (meth) acrylic acid alkyl ester (b) having an alkyl group having 1 to 4 carbon atoms in addition to monomer (a) as a constituent monomer, It is preferable from the viewpoint of the effect of improving the viscosity index.
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 and the like. Of these, methyl (meth) acrylate and ethyl (meth) acrylate are preferred, and methyl (meth) acrylate is more preferred.

(A) is a copolymer having (meth) acrylic acid alkyl ester (c) having a linear alkyl group having 8 to 28 carbon atoms as a constituent monomer in addition to monomer (a). Is preferable from the viewpoint of the effect of improving the viscosity index.
As the (meth) acrylic acid alkyl ester (c) having a linear alkyl group having 8 to 28 carbon atoms, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n- (meth) acrylic acid Decyl, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, (meth) Examples include n-octadecyl acrylate and n-triacontyl (meth) acrylate.
Among (c), preferred is a (meth) acrylic acid ester having a linear alkyl group having 10 to 18 carbon atoms. A (meth) acrylic acid ester having a linear alkyl group having 11 to 17 carbon atoms is more preferable, and a (meth) acrylic acid ester having a linear alkyl group having 12 to 16 carbon atoms is particularly preferable.

一般式（５）におけるＲ¹⁴は、水素原子又はメチル基である。
一般式（５）におけるＲ¹⁵及びＲ¹⁶は、それぞれ独立に炭素数９〜１８のアルキル基であり、Ｒ¹⁵とＲ¹⁶の合計炭素数が１８〜３０である。
炭素数９〜１８のアルキル基としては、炭素数９〜１８の直鎖アルキル基及び炭素数９〜１８の分岐のアルキル基が挙げられる。
炭素数９〜１８の直鎖アルキル基としては、ｎ−ノニル基、ｎ−デシル基、ｎ−ウンデシル基、ｎ−ドデシル基、ｎ−トリデシル基、ｎ−テトラデシル基、ｎ−ペンタデシル基、ｎ−ヘキサデシル基、ｎ−ヘプタデシル基及びｎ−オクタデシル基等が挙げられる。
炭素数９〜１８の分岐アルキル基としては、イソノニル基、３，５，５−トリメチルヘキシル基、イソデシル基、２，４，６−トリメチルヘプチル基、２−メチル−ｎ−ノニル基、イソウンデシル基、２−メチル−ｎ−デシル基、２−エチル−ｎ−ノニル基、イソドデシル基、２−エチル−ｎ−ドデシル基、２−エチル−ｎ−トリデシル基、２−メチル−ｎ−テトラデシル基、イソヘキサデシル基、２−オクチルノニル基、２−ヘキシルウンデシル基、２−エチルペンタデシル基、２−（３−メチルヘキシル）−７−メチル−ノニル基及びイソオクタデシル基等が挙げられる。 It is a base oil that (A) is a copolymer having the monomer (d) represented by the following general formula (5) as a constituent monomer in addition to the monomers (a) to (c) From the viewpoint of solubility in water.

R ¹⁴ in the general formula (5) is a hydrogen atom or a methyl group.
R ¹⁵ and R ¹⁶ in the general formula (5) are each independently an alkyl group having 9 to 18 carbon atoms, and the total carbon number of R ¹⁵ and R ¹⁶ is 18 to 30.
Examples of the alkyl group having 9 to 18 carbon atoms include a linear alkyl group having 9 to 18 carbon atoms and a branched alkyl group having 9 to 18 carbon atoms.
Examples of the linear alkyl group having 9 to 18 carbon atoms include n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n- Examples include a hexadecyl group, an n-heptadecyl group, and an n-octadecyl group.
Examples of the branched alkyl group having 9 to 18 carbon atoms include isononyl group, 3,5,5-trimethylhexyl group, isodecyl group, 2,4,6-trimethylheptyl group, 2-methyl-n-nonyl group, isoundecyl group, 2-methyl-n-decyl group, 2-ethyl-n-nonyl group, isododecyl group, 2-ethyl-n-dodecyl group, 2-ethyl-n-tridecyl group, 2-methyl-n-tetradecyl group, isohexa Examples include a decyl group, a 2-octylnonyl group, a 2-hexylundecyl group, a 2-ethylpentadecyl group, a 2- (3-methylhexyl) -7-methyl-nonyl group, and an isooctadecyl group.

  Specific examples of the monomer (d) include 2-n-nonyl-n-undecyl (meth) acrylate, 2-isononyl-n-undecyl (meth) acrylate, and 2-n-nonyl-n-tridecyl (meth). Acrylate, 2- (3,5,5-trimethyl-n-hexyl) -n-tetradecyl (meth) acrylate, 2-n-decyl-n-tetradecyl (meth) acrylate, 2- (2,4,6-trimethyl -N-heptyl) -6,8-dimethyl-n-tetradecyl (meth) acrylate, 2- (2-ethyl-n-dodecyl) -16-methyl-n-pentadecyl (meth) acrylate, 2-isodecyl-10- Methyl-n-undecyl (meth) acrylate, 2,4-di-n-octyl-n-undecyl (meth) acrylate, 2-n-dodecyl-n-hex Decyl (meth) acrylate, 2-n-tetradecyl-n-octadecyl (meth) acrylate, 2-n-pentadecyl-n-heptadecyl (meth) acrylate, 2-n-dodecyl-n-eicosyl (meth) acrylate and 2- (4-butyl-n-octyl) -n-eicosyl (meth) acrylate.

  Among (d), 2-n-decyl-n-tetradecyl (meth) acrylate and 2-n-dodecyl-n-hexadecyl (meth) acrylate are preferable from the viewpoint of improving the viscosity index and preventing crystallization. .

(A) is a copolymer having a nitrogen atom-containing vinyl monomer (e) as a constituent monomer in addition to the monomers (a) to (d), in view of improving the viscosity index. To preferred.
Examples of the nitrogen atom-containing vinyl monomer (e) include the following monomers (e1) to (e4).

Nitrogen atom-containing vinyl monomer (e);
Amide group-containing vinyl monomer (e1):
(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 (e2):
4-nitrostyrene etc. are mentioned.

Primary to tertiary amino group-containing vinyl monomer (e3):
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 (e4):
Examples include (meth) acrylonitrile.

  Among (e), preferred are (e1) and (e3), and more preferred are diphenylamine (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) ) Acrylamide, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

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

Aliphatic hydrocarbon vinyl monomer (f);
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 (g);
Examples include cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, and ethylidenebicycloheptene.

Aromatic hydrocarbon vinyl monomer (h);
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 (i);
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 (j);
Examples thereof include glycidyl (meth) acrylate and glycidyl (meth) allyl ether.

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

Phosphorus atom-containing monomer (l);
(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.], (meth) acryloyloxyalkyl (carbon number 2-4) phosphonic acid [(meth) Acryloyloxyethyl phosphonic acid, etc.] and alkenyl (C2-C12) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid, octenyl phosphonic acid, etc.] and the like.

An ester of an unsaturated polycarboxylic acid (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.

Hydroxyl group-containing vinyl monomer (n);
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-C12 alkenediol [1-bute -3-ol, 2-buten-1-ol, 2-butene-1,4-diol and the like], hydroxyalkyl (C1-6) alkenyl (C3-10) ether (2-hydroxyethylpropenyl ether) Etc.), alkenyl (3 to 10 carbon atoms) ethers or (meth) acrylates of polyhydric (3 to 8 valent) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, saccharides, sucrose, etc.) [sucrose (meth) Allyl ether] and the like.

Polyoxyalkylene chain-containing vinyl monomer (o);
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 to 100)], mono (meth) acrylates of polyoxyalkylene glycol or polyoxyalkylene polyol alkyl (C1 to C4) ether [polyethylene glycol (number average molecular weight 100 to 300) mono (meth) acrylate, polypropylene glycol (Number average molecular weight 130-500) mono (meth) acrylate, methoxypolyethylene glycol (number average molecular weight 110-310) (meth) acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth) acrylate and mono Meth) acrylic acid polyoxyethylene (number average molecular weight 150 to 230) sorbitan etc.] and the like.

The proportion of (a) constituting (A) is preferably 5 to 80% by weight, more preferably 10 to 70% by weight, based on the weight of (A), from the viewpoint of the viscosity index improving effect and low temperature viscosity. %, Particularly preferably 20 to 60% by weight, more preferably 20 to 50% by weight.
The proportion of (b) constituting (A) is preferably 0 to 45% by weight, more preferably 10 to 42.%, based on the weight of (A), from the viewpoint of the viscosity index improving effect and low temperature viscosity. 5% by weight, particularly preferably 20 to 40% by weight.
The proportion of (c) constituting (A) is preferably 0 to 60% by weight, more preferably 10 to 50% by weight, based on the weight of (A), from the viewpoint of the viscosity index improving effect and low temperature viscosity. %, Particularly preferably 15 to 45% by weight.
The proportion of (d) constituting (A) is preferably 0 to 45% by weight, more preferably 5 to 5%, based on the weight of (A), from the viewpoint of solubility in base oil and low temperature viscosity. It is 40% by weight, particularly preferably 10 to 35% by weight.
The proportion of (e) constituting (A) is preferably 0 to 10% by weight, more preferably 1 to 9% by weight, based on the weight of (A), from the viewpoint of the effect of improving the viscosity index and low temperature viscosity. %, Particularly preferably 2 to 8% by weight.
The proportion of (f) to (o) constituting (A) is preferably 0 to 20% by weight based on the weight of (A), respectively, from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity. Preferably it is 2 to 18 weight%, Most preferably, it is 5 to 15 weight%.

The solubility parameter (hereinafter abbreviated as SP value) of (A) is 7.3 to 11 (cal / cm ³ ) ^1/2 from the viewpoint of the effect of improving the viscosity index and the solubility in the base oil, preferably Is 8.0 to 10.0 (cal / cm ³ ) ^1/2 , more preferably 9.0 to 9.5 (cal / cm ³ ) ^1/2 , and particularly preferably 9.1 to 9.3 (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 (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 11 (cal / cm ³ ) ^1/2 by appropriately adjusting the SP value and molar fraction of the monomer used.

* ：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 The weight average molecular weight (hereinafter abbreviated as Mw) of (A) is preferably 5,000 to 1,000,000 from the viewpoint of the effect of improving the viscosity index and low temperature viscosity, and a more preferable range is the lubricating oil composition. Depending on the application, the range shown in Table 1.

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

In addition, Mw of (A) can be measured on condition of the following by gel permeation chromatography.
<Measurement conditions of Mw>
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
Detector: Refractive index detector Standard: Polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190, 000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

The crystallization temperature of (A) is preferably −20 ° C. or less, more preferably −30 ° C. or less, particularly preferably −40 ° C. or less, and most preferably −50 ° C. or less from the viewpoint of low temperature viscosity.
The crystallization temperature of (A) was determined by using a differential scanning calorimeter “UNIX (registered trademark) DSC7” (manufactured by PERKIN-ELMER), using 5 mg of a viscosity index improver as a sample, and an isothermal rate of 10 ° C./min. Is the crystallization temperature observed when cooled from 100 ° C. to −70 ° C.

(A) can be obtained by a known production method. Specific examples include a method obtained by solution polymerization of the 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.

In the viscosity index improver composition (R) of the present invention, (A) and an alkyl (meth) acrylate ester (co) polymer (B) other than (A) may be used in combination.
(B) is not particularly limited as long as it is an alkyl (meth) acrylate polymer other than (A), but (meth) acrylic acid alkyl ester having a linear alkyl group having 1 to 15 carbon atoms, etc. Can be mentioned.
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 to 30% by weight and more preferably 0.01% from the viewpoint of low temperature viscosity based on the weight of (A). -20% by weight, particularly preferably 0.01-10% by weight.

The viscosity index improver composition (R) of the present invention comprises an ester-based lubricating base oil (S) having a kinematic viscosity at 100 ° C. of 1 to 30 mm ² / s.

  Examples of the ester lubricant base oil (S) include monoester lubricant base oil (S1), diester lubricant base oil (S2), and polyester lubricant base oil (S3).

Examples of the monoester-based lubricating base oil (S1) include esters of monohydric alcohols having 1 to 24 carbon atoms and monovalent carboxylic acids having 2 to 24 carbon atoms.
The monohydric alcohol having 1 to 24 carbon atoms may be linear or branched, specifically, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, hexanol, heptanol, Octanol, 2-ethylhexanol, nonanol, decanol, isodecanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, 2-hexyldecanol, isostearyl alcohol, 2-octyldodecanol and 2-decyltetradecane And the like.

  The monovalent carboxylic acid having 2 to 24 carbon atoms may be linear or branched, and specifically, an aliphatic monovalent carboxylic acid having 2 to 24 carbon atoms (acetic acid, n-butanoic acid). , Isopentanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, n-decanoic acid, isodecanoic acid, n-dodecanoic acid, n- Tetradecanoic acid, n-pentadecanoic acid, n-hexadecanoic acid, 2-hexyldecanoic acid, n-stearic acid, n-eicosanoic acid, 2-octyldodecanoic acid and 2-decyltetradecanoic acid), and aromatics having 7 to 24 carbon atoms Group monovalent carboxylic acids (benzoic acid, ethylbenzoic acid, cinnamic acid, t-butylbenzoic acid and the like).

  Specific examples of the monoester-based lubricant base oil (S1) include n-ethyl butanoate, octyl n-hexanoate, ethyl 2-ethylhexanoate, methyl n-tetradecanoate, ethyl n-pentadecanoate, n-stearate. Examples include octyl acid and ethyl 2-decyltetradecanoate.

  Diester-based lubricating base oil (S2) includes diester (S2-1) of monohydric alcohol having 1 to 24 carbon atoms and divalent carboxylic acid having 2 to 24 carbon atoms, dihydric alcohol having 2 to 24 carbon atoms And diester (S2-2) of monovalent carboxylic acid having 2 to 24 carbon atoms and diester (S2-3) of dihydric alcohol having 1 to 24 carbon atoms and divalent carboxylic acid having 2 to 24 carbon atoms. Can be mentioned.

Examples of the monovalent alcohol having 1 to 24 carbon atoms constituting (S2-1) include those described above.
The divalent carboxylic acid having 2 to 24 carbon atoms may be linear or branched, and specifically, an aliphatic dicarboxylic acid having 2 to 24 carbon atoms (succinic acid, adipic acid, octane dicarboxylic acid). Acid, glutaric acid, malic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid and decylsuccinic acid), alicyclic dicarboxylic acid having 6 to 24 carbon atoms (1,4-dicarboxycyclohexane) And 1,4-dicarboxycycloheptanoic acid) and the like], and aromatic dicarboxylic acids having 8 to 24 carbon atoms (phthalic acid, isophthalic acid, terephthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid and 4 , 4′-biphenyldicarboxylic acid and the like).

  Specific examples of (S2-1) include diethyl adipate, di-n-octyl adipate, di-n-decyl adipate, di-n-nonyl octanedicarboxylate, di-n-octyl decanedicarboxylate, decane Examples include di-2-ethylhexyl dicarboxylate, di-n-octyl octadecane dicarboxylate, di-n-octyl sebacate, di-n-stearyl terephthalate, and dimethyl 4,4′-biphenyldicarboxylate.

  Examples of the dihydric alcohol having 2 to 24 carbon atoms constituting (S2-2) include alkylene ether glycols having 2 to 24 carbon atoms (ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12- Dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol, 1,2-propylene glycol, neopentyl glycol, 2,2-diethyl- 1,3-propanediol, alkylene ether glycol having 4 to 24 carbon atoms [diethylene Glycol, triethylene glycol, poly (degree of polymerization = 4-12) ethylene glycol, dipropylene glycol, poly (degree of polymerization = 3-8) propylene glycol, ditetramethylene glycol and poly (degree of polymerization = 2-6) tetramethylene Glycols, etc.], alicyclic diols having 4 to 24 carbon atoms (1,4-dihydroxymethylcyclohexane and hydrogenated bisphenol A, etc.), alkylene oxides of the above alicyclic diols (hereinafter abbreviated as AO) [ethylene oxide (hereinafter referred to as "Oxides") EO), propylene oxide (hereinafter abbreviated as PO), butylene oxide (hereinafter abbreviated as BO), etc.] adducts (addition moles 1 to 4); bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.) AO (EO, PO, BO, etc.) Adducts (addition molar number 1-4); polylactone diols (poly -ε- caprolactone diol); and polybutadiene diol.

  Examples of the monovalent carboxylic acid having 2 to 24 carbon atoms constituting (S2-2) include those described above.

  Specific examples of (S2-2) include a diester composed of 2 moles of n-stearic acid and 1 mole of ethylene glycol, a diester composed of 2 moles of 2-ethylhexanoic acid and 1 mole of dipropylene glycol, and Examples include diesters composed of 2 moles of n-butanoic acid and 1 mole of bisphenol A.

Examples of the divalent alcohol having 1 to 24 carbon atoms and the divalent carboxylic acid having 2 to 24 carbon atoms constituting (S2-3) include those described above.
Specific examples of (S2-3) include a diester composed of 1 mol of adipic acid and 1 mol of dipropylene glycol, and a diester composed of 1 mol of phthalic acid and 1 mol of triethylene glycol.

  Examples of the polyester-based lubricating base oil (S3) include esters (S3-1) of 3- to 6-carbon alcohols having 2 to 24 carbon atoms and monovalent carboxylic acids having 2 to 24 carbon atoms, 3 having 2 to 24 carbon atoms. Esters (S3-2) of hexavalent alcohols and C2-C24 divalent carboxylic acids, esters of C1-C24 monohydric alcohols and C2-C24 3-6 carboxylic acids ( S3-3), an ester (S3-4) of a dihydric alcohol having 2 to 24 carbon atoms and a 3 to 6 carboxylic acid having 2 to 24 carbon atoms, a 3 to 6 alcohol having 2 to 24 carbon atoms and the carbon number Examples include esters (S3-5) of 2 to 24 with 3-6 carboxylic acids.

The C2-24 trivalent alcohol constituting (S3-1) is a C2-24 trivalent alcohol [glycerin, 1,2,4-trihydroxybutane, 2,3,4- Trihydroxypentane, 1,1,1-tris (hydroxymethyl) ethane and 1,2,6-trihydroxyhexane, 1,2,3-trihydroxyheptane, etc.], tetravalent alcohols having 2 to 24 carbon atoms (penta Erythritol and the like), pentavalent alcohols having 2 to 24 carbon atoms (such as xylitol and arabitol), hexavalent alcohols having 2 to 24 carbon atoms (such as sorbitol and mannitol) and the like.
Examples of the monovalent carboxylic acid having 2 to 24 carbon atoms constituting (S3-1) include those described above.

  Specific examples of (S3-1) include triester composed of 1 mol of glycerin and 3 mol of acetic acid, tetraester composed of 1 mol of pentaerythritol and 4 mol of n-butanoic acid, 1 mol of sorbitol and acetic acid. Examples include hexaesters composed of 6 mol.

The above-mentioned thing is mentioned as C2-C24 3-6 hydric alcohol and C2-C24 divalent carboxylic acid which comprise (S3-2).
Specific examples of (S3-2) include a diester composed of 1 mol of glycerin and 1 mol of malic acid, a diester composed of 1 mol of sorbitol and 1 mol of adipic acid, and the like.

Examples of the monovalent alcohol having 1 to 24 carbon atoms constituting (S3-3) include those described above.
Examples of the tri- or hexavalent carboxylic acid having 2 to 24 carbon atoms include trimellitic acid, pyromellitic acid, ethylenediaminetetraacetic acid, cyclopentanetetracarboxylic acid, triethylenetetraminehexaacetic acid, and cyclohexanehexacarboxylic acid.

  Specific examples of (S3-3) include a triester composed of 1 mole of trimellitic acid and 3 moles of methanol, and a tetraester composed of 1 mole of pyromellitic acid and 4 moles of isopropanol.

Examples of the divalent alcohol having 2 to 24 carbon atoms and the 3- to 6-valent carboxylic acid having 2 to 24 carbon atoms constituting (S3-4) include those described above.
Specific examples of (S3-4) include a diester composed of 1 mol of triethylene glycol and 1 mol of trimellitic acid, a tetraester composed of 2 mol of triethylene glycol and 1 mol of pyromellitic acid, and the like. It is done.

The above-mentioned thing is mentioned as a C3-C24 3-6 hydric alcohol and C2-C24 3-6 carboxylic acid which comprise (S3-5).
Specific examples of (S3-5) include a diester composed of 1 mol of glycerin and 1 mol of trimellitic acid, a diester composed of 1 mol of sorbitol and 1 mol of trimellitic acid, and the like.

Of the ester-based lubricating base oil (S), the monoester-based lubricating base oil (S1) and the diester-based lubricating base oil (S2) are preferable from the viewpoint of the effect of improving the viscosity index. , (S1), (S2-1) and (S2-2), particularly preferred are (S2-1) and (S2-2).
In addition, (S) may be used individually by 1 type and may use 2 or more types together.

Kinematic viscosity at 100 ° C. of the ester-based lubricating oil base oil (S) is 1 to 30 mm ² / s, from the viewpoint of the viscosity index improving effect, preferably 1.5~20mm ² / s, more preferably 1.5 ˜10 mm ² / s.

  The viscosity index of (S) is preferably 80 or more, more preferably 100 or more, and particularly preferably 105 to 180, from the viewpoint of the effect of improving the viscosity index. The viscosity index of (S) can be measured by the method of JIS K2283-1993.

  The pour point of (S) is preferably −5 ° C. or lower, more preferably −15 to −70 ° C., from the viewpoint of the low temperature viscosity of the lubricating oil composition. In addition, the pour point of (S) can be measured by the method of JIS K2269-1993.

In addition to (A) and (S), the viscosity index improver composition (R) of the present invention contains a lubricating base oil (T) having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s. Also good. By containing (T), the viscosity index improving effect of the viscosity index improver composition (R) of the present invention is improved.
(T) includes mineral oil (solvent refined oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil by hydrocracking of isoparaffin, naphthenic oil, etc.), synthetic lubricant (hydrocarbon synthetic lubricant) Oil (poly-α-olefin based synthetic lubricating oil, etc.)] and mixtures thereof. Of these, mineral oil is preferred from the viewpoint of solubility of (A).

The kinematic viscosity (measured according to JIS-K2283) of (T) at 100 ° C. is preferably 1 to ²⁰ mm ² / s, more preferably 1.5 to 15 mm, from the viewpoint of the effect of improving the viscosity index and evaporation loss. ² / s, particularly preferably ² to 10 mm ² / s. The kinematic viscosity at 100 ° C. of (T) can be measured by the method of JIS-K2283.
The viscosity index of (T) is preferably 90 or more, more preferably 100 or more, from the viewpoint of the effect of improving the viscosity index. Moreover, from a viewpoint of the low temperature viscosity of a lubricating oil composition, Preferably it is 170 or less, More preferably, it is 160 or less. The viscosity index of (T) can be measured by the method of JIS K2283.
The cloud point (measured according to JIS-K2269) of (T) is preferably −5 ° C. or lower, more preferably −15 ° C. or lower, from the viewpoint of low temperature viscosity. In addition, the cloud point of (T) can be measured by the method by JIS-K2269.

The content of (A) in the viscosity index improver composition (R) of the present invention is preferably 10 to 99.9 based on the weight of the viscosity index improver composition (R) from the viewpoint of the effect of improving the viscosity index. % By weight, more preferably 15 to 90% by weight, particularly preferably 20 to 85% by weight, more preferably 30 to 80% by weight, and most preferably 40 to 75% by weight.
The content of (S) in the viscosity index improver composition (R) of the present invention is improved from the viewpoint of the effect of improving the viscosity index and the oxidation stability and storage stability of the viscosity index improver composition (R). Based on the weight of the agent composition (R), it is preferably 0.1 to 90% by weight, more preferably 1 to 80% by weight, particularly preferably 5 to 70% by weight, more preferably 10 to 60% by weight, Most preferably, it is 20 to 50% by weight.
The content of (T) in the viscosity index improver composition (R) of the present invention is preferably 0 to 50% by weight, more preferably 10 to 10% by weight, based on the weight of the viscosity index improver composition (R). It is 40% by weight, particularly preferably 20 to 30% by weight.

The manufacturing method of the viscosity index improver composition (R) of the present invention has a constitutional requirement that (A) is obtained by polymerizing a monomer containing (a) in the presence of (S). . In the presence of (S), a monomer comprising (a) is polymerized to obtain (A), whereby a monomer comprising (a) is polymerized to obtain (A). After that, the viscosity index improver composition (R) is more effective in improving the viscosity index than when the viscosity index improver composition (R) is prepared by mixing (A) and (S). .
Examples of (a) constituting (S) and (A) include those described above. Examples of the monomer copolymerizable with (a) include the above (b) to (o).

As a method for producing the viscosity index improver composition (R) of the present invention, in the presence of a polymerization catalyst, a monomer selected from (a) and, if necessary, (b) to (o) is contained in (S). And the following method may be mentioned.
[1] A method in which a monomer is previously dissolved in (S) and a polymerization catalyst is dropped.
[2] A method of dropping a monomer and a polymerization catalyst into (S).
[3] A method in which a monomer is dropped into (S) containing a polymerization catalyst.
[4] A method in which a monomer and a polymerization catalyst are charged into (S) in advance.

As a polymerization catalyst, the thing similar to what was illustrated with the manufacturing method of (A) is mentioned.
The polymerization temperature is preferably 25 to 140 ° C, more preferably 50 to 120 ° C. In addition to solution polymerization, (A) can be polymerized 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.

  In the method for producing the viscosity index improver composition (R) of the present invention, (A) is obtained by polymerizing a monomer containing (a) in the presence of (S) and (T). Is preferable because the viscosity index improving effect of the obtained viscosity index improver composition (R) is further excellent. Examples of (T) include those described above.

The total weight of the monomers used in the method for producing the viscosity index improver composition (R) of the present invention is 100 weights of the obtained viscosity index improver composition (R) from the viewpoint that the polymerization reaction proceeds easily. The amount is preferably 20 to 80 parts by weight, more preferably 20 to 70 parts by weight, and particularly preferably 25 to 50 parts by weight with respect to parts.
The weight of (S) used in the method for producing the viscosity index improver composition (R) of the present invention is 100 parts by weight of the resulting viscosity index improver composition (R) from the viewpoint that the polymerization reaction proceeds easily. Is preferably 20 to 80 parts by weight, more preferably 25 to 75 parts by weight, and particularly preferably 30 to 50 parts by weight.
The weight of (T) used in the method for producing the viscosity index improver composition (R) of the present invention is 100 parts by weight of the resulting viscosity index improver composition (R) from the viewpoint that the polymerization reaction proceeds easily. The amount is preferably 0 to 80 parts by weight, more preferably 5 to 55 parts by weight, and particularly preferably 20 to 45 parts by weight.

The lubricating oil composition of the present invention comprises the viscosity index improver composition (R) of the present invention and a lubricating base oil (U).
Examples of (U) include the same as (S) and (T). Kinematic viscosity at 100 ° C. of (U), from the viewpoint of the viscosity index improving effect, preferably from 1.5 to 15 mm ² / s, more preferably 1.5 to 10 mm ² / s.

The preferred range of the kinematic viscosity at 100 ° C. of (U) varies depending on the use of the lubricating oil composition of the present invention.
When the lubricating oil composition is engine oil or gear oil, the kinematic viscosity at 100 ° C. of (U) is preferably 3 to 10 mm ² / s.
When the lubricating oil composition is an automatic transmission oil (ATF, belt-CVTF and MTF), the kinematic viscosity at 100 ° C. of (U) is preferably ² to 6 mm ² / s.
When the lubricating oil composition is a traction oil, the kinematic viscosity at 100 ° C. of (U) is preferably 1 to 5 mm ² / s.

The preferable range of the content rate of the viscosity index improver composition (R) varies depending on the use of the lubricating oil composition of the present invention.
When the lubricating oil composition is an engine oil, the viscosity index improver composition (R) is contained so as to contain 0.5 to 15% by weight as (A) based on the weight of the lubricating oil composition. Is preferred.
When the lubricating oil composition is gear oil, it is preferable that the viscosity index improver composition (R) is contained so as to contain 3 to 30% by weight as (A) based on the weight of the lubricating oil composition. .
When the lubricating oil composition is an automatic transmission oil (ATF, belt-CVTF and MFT), the viscosity index improver composition (A) is contained in an amount of 2 to 25% by weight based on the weight of the lubricating oil composition ( R) is preferably contained.
When the lubricating oil composition is a traction oil, the viscosity index improver composition (R) is contained so as to contain 0.5 to 15% by weight as (A) based on the weight of the lubricating oil composition. Is preferred.
When the lubricating oil composition is a hydraulic oil, the viscosity index improver composition (R) is contained so as to contain 0.5 to 25% by weight as (A) based on the weight of the lubricating oil composition. Is preferred.

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 (benzotriazole and 1,3,4-thiodiazolyl-2,5-
Bisdialkyldithiocarbamate, etc.).

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

<Production Example 1>
In a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, a dehydration device, and an air introduction tube, 158.3 parts by weight of 3,5-dimethyl-4-octanol (manufactured by Aldrich), p-toluenesulfonic acid [Tokyo Kasei Co., Ltd.] 9 parts by weight, hydroquinone [Wako Pure Chemical Industries, Ltd.] 0.04 parts by weight and methacrylic acid [Kuraray Co., Ltd.] 111.9 parts by weight are introduced, and air is introduced into the liquid layer. The reaction was performed at 120 ° C. for 5 hours. The water produced during the reaction was removed with a dehydrator. After cooling to room temperature, the mixture was neutralized with 132 parts by weight of a 10% by weight aqueous sodium hydroxide solution, and the organic layer was collected. The organic layer was dried under reduced pressure (0.003 MPa) at 100 ° C. for 2 hours to obtain a monomer (a-1).

<Production Example 2>
In Production Example 1, the same procedure as in Production Example 1 was carried out except that 158.3 parts by weight of 5-dimethyl-4-octanol was changed to 172.3 parts by weight of 2,4-dimethyl-4-nonanol (manufactured by Aldrich). Thus, monomer (a-2) was obtained.

<Example 1>
In a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen introduction tube, 20 parts by weight of toluene, 100 parts by weight of the monomers listed in Table 2 [(a-1) 30 parts by weight, (b-1) ) 33 parts by weight, (c-1) 37 parts by weight of mixture], 0.33 parts by weight of azobisvaleronitrile as a radical polymerization initiator was added, and after nitrogen substitution, polymerization was carried out at 80 ° C. for 5 hours in a sealed state. Reaction was performed. After cooling to room temperature, 500 parts by weight of methanol was added to precipitate a copolymer, and methanol was removed by decantation. Further, 300 parts by weight of methanol was added, stirred for 10 minutes, and the process of removing methanol by decantation was repeated twice, followed by drying at 100 ° C. for 4 hours under reduced pressure (0.003 MPa). Thereto was added 100 parts by weight of the diluent oil (S-1) shown in Table 2, and the mixture was stirred at 120 ° C. for 3 hours to obtain a viscosity index improver (R1) comprising the copolymer (A1). The SP value of the obtained copolymer (A1) was calculated by the above method, and Mw was measured by the above method. The results are shown in Table 2.

<Examples 2-8, Comparative Examples 1-3>
In Example 1, 100 parts by weight of the monomer [mixture of 30 parts by weight of (a-1), 33 parts by weight of (b-1), 37 parts by weight of (c-1)] are each shown in Table 2. Copolymers (A2) to (A8) are obtained in the same manner as in Example 1 except that 100 parts by weight of the monomer is changed and 100 parts by weight of (S-1) is changed to the diluent oil shown in Table 2, respectively. Viscosity index improvers (R2) to (R8) and (V1) to (V3) comprising (H1) to (H3) were obtained. The SP values of the obtained copolymers (A2) to (A8) and (H1) to (H3) were calculated by the above method, and Mw was measured by the above method. The results are shown in Table 2.

The monomers listed in Table 2 are as follows.
(A-1): 1- (1′-methyl-n-propyl) -2-methyl-n-pentyl methacrylate (a-2): 1-isobutyl-1-methyl-n-hexyl methacrylate (b-1) : Methyl methacrylate (c-1): n-tetradecyl methacrylate (c-2): n-hexadecyl methacrylate (d-1): 2-n-decyl-n-tetradecyl methacrylate (e-1): dimethyl Aminoethyl methacrylate
(N-1): Hydroxyethyl methacrylate The diluent oil described in Table 2 is as follows.
(S-1): Dioctyl sebacate [100 ° C. kinematic viscosity: 3.23 mm ² / s, 40 ° C. kinematic viscosity: 11.56 mm ² / s, viscosity index: 151, manufactured by Toyokuni Oil Co., Ltd.]
(T-1): “YUBASE4” [mineral oil, kinematic viscosity at 100 ° C .: 4.25 mm ² / s, kinematic viscosity at 40 ° C .: 10.7 mm ² / s, viscosity index: 101, manufactured by SKOIL Corporation]

<Examples 9 to 16, Comparative Examples 4 to 6>
(T-1) is charged into a stainless steel container equipped with a stirrer, and the resulting lubricating oil composition has an HTHS viscosity at 150 ° C. of 2.60 ± 0.02 (mm ² / s). Viscosity index improver compositions (R1) to (R8) and (V1) to (V3) were added to obtain lubricating oil compositions (X1) to (X8) and (Y1) to (Y3), respectively.
The kinematic viscosity at 40 ° C. and 100 ° C., the viscosity index, the HTHS viscosity at 80 ° C. and 150 ° C., and the low temperature viscosity at −40 ° C. of the lubricating oil compositions (X1) to (X8) and (Y1) to (Y3) were measured. . Each measurement was performed by the following evaluation methods. The results are shown in Table 3.

<Measuring method of kinematic viscosity at 40 ° C. and 100 ° C. of lubricating oil composition>
It was measured by the method of ASTM D445.

<Measuring method of viscosity index of lubricating oil composition>
It measured by the method of JIS-K2283-1993.

<Method for Measuring HTHS Viscosity of Lubricating Oil Composition at 80 ° C. and 150 ° C.>
It was measured by the method of ASTM D4683.

<Method for Measuring Low Temperature Viscosity of Lubricating Oil Composition at −40 ° C.>
It was measured by the method of ASTM D5293.

  As is apparent from the results in Table 3, the lubricating oil compositions (Examples 9 to 16) containing the viscosity index improver composition (R) of the present invention are the lubricating oil compositions of Comparative Examples 4 to 6. Compared to the above, the effect of improving the viscosity index is high and the kinematic viscosity at 40 ° C. is low.

The lubricating oil composition comprising the viscosity index improver composition (R) of the present invention includes a drive system lubricating oil (MTF, differential gear oil, ATF, belt-CVTF, etc.), hydraulic oil (mechanical hydraulic oil, Power steering oil, shock absorber oil, etc.), engine oil (gasoline, diesel, etc.) and traction oil are suitable.

Claims (14)

A (co) polymer having the monomer (a) represented by the following general formula (1) as an essential constituent monomer and a solubility parameter of 7.3 to 11 (cal / cm ³ ) ^1/2 A viscosity index improver composition (R) comprising (A) and an ester-based lubricating base oil (S) having a kinematic viscosity at 100 ° C. of 1 to 30 mm ² / s.

[R ¹ is a hydrogen atom or a methyl group; X is an alkylene group having 2 to 4 carbon atoms; n is a number from 0 to 20, and when n is 2 or more, X may be the same or different, and (XO ) The n moiety may be a random bond or a block bond; R ² is a branched alkyl group having 4 to 13 carbon atoms represented by the general formula (2), the general formula (3), or the general formula (4). ]

[R ³ and R ⁴ are each independently a linear or branched alkyl group having 1 to 11 carbon atoms; R ⁵ is a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, and R ^{3 to} R ⁵ The total carbon number of is 3-12. ]

[R ⁶ and R ⁷ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms; R ⁸ , R ⁹ and R ¹⁰ are each independently a linear or branched group having 1 to 9 carbon atoms; an alkyl ^group, the total number of carbon atoms of R 6 to R ¹⁰ is 3-11. ]

[R ¹¹ , R ¹² and R ¹³ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms, and the total carbon number of R ^{11 to} R ¹³ is 3 to 10. ] The viscosity index improver composition (R) according to claim 1, further comprising a lubricating base oil (T) having a kinematic viscosity at 100 ° C of 1 to 20 mm ² / s.   The viscosity index improver composition (R) according to claim 1 or 2, wherein (S) is a monoester lubricant base oil (S1) and / or a diester lubricant base oil (S2).   The content of (A) based on the weight of (R) is 10 to 99.9% by weight, and the content of (S) is 0.1 to 90% by weight. Viscosity index improver composition (R). The solubility parameter of (S) is 8.5 to 10 (cal / cm ³ ) ^1/2. The viscosity index improver composition (R) according to any one of claims 1 to 4.   (A) is a copolymer containing (meth) acrylic acid alkyl (b) having an alkyl group having 1 to 4 carbon atoms as a constituent monomer of (A). The viscosity index improver composition (R) according to any one of the above.   (A) is a copolymer comprising (meth) acrylic acid alkyl ester (c) having a linear alkyl group having 8 to 28 carbon atoms as a constituent monomer of (A). The viscosity index improver composition (R) according to any one of 1 to 6. (A) is a copolymer further containing a monomer (d) represented by the following general formula (5) as a constituent monomer of (A). The viscosity index improver composition (R) described.

[R ¹⁴ is a hydrogen atom or a methyl group; R ¹⁵ and R ¹⁶ are each independently an alkyl group having 9 to 18 carbon atoms, the total number of carbon atoms in R ¹⁵ and R ¹⁶ is 18 to 30. ]   The viscosity index improvement according to any one of claims 1 to 8, wherein (A) is a copolymer further comprising a nitrogen atom-containing vinyl monomer (e) as a constituent monomer of (A). Agent composition (R).   The viscosity index improver composition (R) according to any one of claims 1 to 9, wherein the weight average molecular weight of (A) is 5,000 to 1,000,000.   The viscosity index improver composition (R) according to any one of claims 1 to 10, wherein the crystallization temperature of (A) is -20C or lower.   The (co) polymer (B) other than (A) is further contained in an amount of 0.01 to 30% by weight based on the weight of (A). Viscosity index improver composition (R).   A lubricating oil composition comprising (R) according to any one of claims 1 to 12 and a lubricating base oil (U). A (co) polymer (A) having a solubility parameter of 7.3 to 11 (cal / cm ³ ) ^1/2 by polymerizing a monomer containing (a) in the presence of (S) A method for producing a viscosity index improver composition (R) comprising (A) and (S).