JP2017031400A - Viscosity index improver composition and lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viscosity index improver composition excellent in shear stability of a lubricant composition, low in HTHS viscosity of the lubricant composition, hard to increase low temperature viscosity of the lubricant composition and easy to handle under ambient temperature.SOLUTION: There is provided a viscosity index improver composition containing a polymer (A) with a monomer (a) represented by the general formula (1) as a constitutional unit and a base oil and having a value (V1) of 40°C kinetic viscosity divided by 100°C kinetic viscosity in a range of 0.2 to 5.SELECTED DRAWING: None

Description

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

In recent years, in order to reduce CO ₂ emissions and protect petroleum resources, fuel consumption of automobiles has been further demanded. One way to save fuel is to reduce viscous resistance by reducing the viscosity of engine oil. However, when the viscosity is lowered, problems such as liquid leakage and seizure arise. In cold regions, low temperature startability is required. This problem is defined in the US SAE viscosity standard for engine oil (SAEJ300). In the 0W-20 grade, 150 ° C. HTHS viscosity (ASTM D4683 or D5481) under high temperature and high shear is Min. It is specified in 2.6. In addition, in order to guarantee startability in a cold region, the grade has a low-temperature viscosity at −40 ° C. of 60,000 mPa · s or less and no yield stress (ASTM D4684). For fuel saving, engine oil having a lower HTHS viscosity in an effective temperature range of 80 ° C. or 100 ° C. after satisfying the above standards is required, and various viscosity index improvers have been proposed. As such a viscosity index improver, methacrylic acid ester copolymers (Patent Documents 1 to 4), olefin copolymers (Patent Document 5), comb copolymers (Patent Documents 6 to 8) and the like are known. ing.
However, the above viscosity index improver is not yet sufficient for reducing the 100 ° C. HTHS viscosity when added to an engine oil composition, is susceptible to viscosity reduction due to shearing, and increases the viscosity at low temperatures. was there.
Further, the viscosity index improver is distributed in a state in which the polymer is diluted with a dilutable mineral oil or the like, but it is required to increase the polymer concentration in order to reduce the cost of transportation. On the other hand, when the polymer concentration is increased, the viscosity increases, and since it cannot be handled at the atmospheric temperature, it is necessary to heat, and there is a problem that a heating facility or the like is required.

Japanese Patent No. 2732187 Japanese Patent No. 2754343 Japanese Patent No. 3831203 Japanese Patent No. 3999307 JP 2005-200454 A Japanese Patent No. 3474918 Special table 2008-546894 gazette Special table 2010-532805 gazette

  The object of the present invention is to improve the shear stability of the lubricating oil composition, to lower the HTHS viscosity of the lubricating oil composition, to hardly increase the low temperature viscosity of the lubricating oil composition, and to maintain the active ingredient concentration at atmospheric temperature. It is an object to provide a viscosity index improver composition that is easy to handle.

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention relates to a viscosity index improver composition comprising a polymer (A) having the ethylenically unsaturated monomer (a) represented by the general formula (1) as a constituent monomer and a base oil. This is a viscosity index improver composition having a value (V1) obtained by dividing the 40 ° C. kinematic viscosity by the 100 ° C. kinematic viscosity in the range of 0.2 to 5.
[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 straight chain having 2 to 4 carbon atoms or a branched alkylene group, m is an integer of 0 to 20, a when m is 2 or more may be the same or different, (AO) _m moiety may be block also coupled with a random bond; R ² is A residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing isobutylene and / or 1,2-butylene as an essential constituent unit; p is a number of 0 or 1]

  The lubricating oil composition comprising the viscosity index improver composition of the present invention is excellent in shear stability, has a low HTHS viscosity in the effective temperature range, and is difficult to increase the low temperature viscosity of the lubricating oil composition. Play.

  The polymer (A) in the present invention is a copolymer having the monomer (a) represented by the general formula (1) as a 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 the HTHS viscosity in the effective temperature range.

M in the general formula (1) is an integer of 0 to 20, and is 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 and the low temperature viscosity.
When m is 2 or more, A may be the same or different, and (AO) _m part may be a random bond or a block bond.

R ² in the general formula (1) is an essential constituent of an isobutylene group (—CH ₂ C (CH ₃ ) ₂ —) and / or a 1,2-butylene group (—CH ₂ CH (CH ₂ CH ₃ ) —). It is a residue of a hydrocarbon polymer as a unit (hereinafter abbreviated as “hydrocarbon polymer”).
In addition, the residue of a hydrocarbon polymer means the part remove | excluding one hydrogen atom from the hydrocarbon polymer.

Examples of the hydrocarbon polymer include polymers having the following (1) to (3) as constituent monomers in addition to 1-butene, isobutene and / or butadiene.
The hydrocarbon polymer may be a block polymer or a random polymer.
(1) Aliphatic unsaturated hydrocarbon [olefin having 2 to 36 carbon atoms (for example, ethylene, propylene, 2-butene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, triacocene, hexatriacocene, etc.) and carbon number 2-36 dienes (for example, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.) and the like]
(2) Alicyclic unsaturated hydrocarbon [for example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, ethylidenebicycloheptene, etc.]
(3) Aromatic group-containing unsaturated hydrocarbon (for example, styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotyl) Benzene, vinyl naphthalene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, etc.).
When the hydrocarbon polymer has a double bond, a part or all of the double bond may be hydrogenated by hydrogenation.

Based on the total number of constituent monomers of the hydrocarbon polymer, the total ratio of isobutylene groups and 1,2-butylene groups is 50 mol% or more, more preferably 55 mol% or more, particularly preferably 60 mol% or more. It is.
The hydrocarbon polymer can be obtained by a known production method (Japanese Patent Publication No. 44-27469).

  The monomer (a) can be obtained by an esterification reaction between a one-terminal hydroxyl group-containing (co) polymer (Y) having a hydroxyl group introduced at one terminal of a hydrocarbon polymer and (meth) acrylic acid.

Specific examples of the one-terminal hydroxyl group-containing (co) polymer (Y) include the following.
Alkylene oxide adduct (Y1); (co) polymer obtained by polymerizing unsaturated hydrocarbon (x) in the presence of an ion polymerization catalyst (sodium catalyst, etc.) to alkylene oxide (ethylene oxide, propylene oxide, etc.) Obtained by adding.
Hydroboration product (Y2): (x) having a terminal double bond, a hydroboration reaction product of the (co) polymer (for example, those described in US Pat. No. 4,316,973) and the like.
Maleic anhydride-ene-aminoalcohol adduct (Y3); (x) having a terminal double bond, the reaction product obtained by the ene reaction between the (co) polymer and maleic anhydride is converted to amino Those obtained by imidization with alcohol.
Hydroformyl-hydride (Y4); (x) having a terminal double bond, obtained by hydroformylation of the (co) polymer and then hydrogenation (for example, JP-A-63-175096) Etc.).
Among (Y), (Y1), (Y2) and (Y3) are preferable, and (Y1) is more preferable.

The number average molecular weight (hereinafter abbreviated as Mn) of (Y) is preferably 1,000 to 25,000, more preferably 2,000 to 20,000, particularly preferably from the viewpoint of shear stability and HTHS viscosity. Is from 3,000 to 15,000, most preferably from 4,000 to 10,000. In addition, Mn of (Y) and the weight average molecular weight (hereinafter abbreviated as Mw) of the (co) polymer (A) described later can be measured by gel permeation chromatography under the following conditions.
<Measurement conditions of Mn and Mw of (Y), Mw of (A)>
Apparatus: “HLC-802A” [manufactured by Tosoh Corporation]
Column: Two “TSK gel GMH6” [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C.
Sample solution: 0.5 mass% tetrahydrofuran solution Solution injection amount: 200 μl
Detection device: Refractive index detector Reference material: Standard polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

  (V1) is a value obtained by dividing the 40 ° C. kinematic viscosity of the viscosity index improver composition by the 100 ° C. kinematic viscosity. Expressed by the calculation formula, (V1) = (40 ° C. kinematic viscosity) / (100 ° C. kinematic viscosity). From the viewpoint of handling properties of the viscosity index improver composition, it is usually 0.2 to 5, more preferably 0.2 to 4, particularly preferably 0.2 to 3, and most preferably 0.2 to 2. If (V1) is less than 0.2, there is a problem in handling properties at production (100 ° C. or more), and if it exceeds 5, there is a problem in handling properties at 40 ° C. (V1) can be adjusted by controlling the amount of monomer (a) used in the polymer (A) and the SP value.

  (V2) is a value obtained by dividing the 80 ° C. kinematic viscosity of the viscosity index improver composition by the 100 ° C. kinematic viscosity. Expressed by the calculation formula, (V2) = (80 ° C. kinematic viscosity) / (100 ° C. kinematic viscosity). From the viewpoint of handling properties of the viscosity index improver composition, it is preferably 0.2 to 10, more preferably 0.3 to 8. (V2) can be adjusted by controlling the amount of monomer (a) used in the polymer (A) and the SP value.

  The concentration of (A) is preferably from 10 to 50% by weight, more preferably from 10 to 40% by weight, particularly preferably from 15 to 50% by weight based on the weight of the viscosity index improver composition from the viewpoint of fluidity during the production of the lubricating oil. It is in the range of 30% by mass.

(A) preferably has a specific solubility parameter (hereinafter abbreviated as SP value) from the viewpoint of the viscosity index of the lubricating oil. The range of SP value becomes like this. Preferably it is 7.0-9.0 (cal / cm < ³ >) < ^1/2 >, More preferably, it is 7.3-8.5 (cal / cm < ³ >) ^1/2 . In addition, SP value in this invention is a value calculated by the method of Fedors method (Polymer Engineering and Science, February, 1974, Vol.14, No.2 P.147-154).
The SP value of (Y) is calculated based on the SP value of each monomer constituting (Y) by the above-mentioned method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (Y) can be adjusted to a desired range by appropriately adjusting the SP value and the mole fraction of the monomer used.

(Y) preferably has a specific solubility parameter (hereinafter abbreviated as SP value) from the viewpoint of solubility in lubricating oil. The range of SP value becomes like this. Preferably it is 7.0-9.0 (cal / cm < ³ >) < ^1/2 >, More preferably, it is 7.3-8.5 (cal / cm < ³ >) ^1/2 . In addition, SP value in this invention is a value calculated by the method of Fedors method (Polymer Engineering and Science, February, 1974, Vol.14, No.2 P.147-154).
The SP value of (Y) is calculated based on the SP value of each monomer constituting (Y) by the above-mentioned method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (Y) can be adjusted to a desired range by appropriately adjusting the SP value and the mole fraction of the monomer used.

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

  The (co) polymer (A) in the present invention is a copolymer having a monomer (b) represented by the following general formula (2) as a constituent monomer in addition to the monomer (a). Is preferable from the viewpoint of the HTHS viscosity at the effective temperature.

[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 Each independently a linear alkyl group having 8 to 24 carbon atoms; q is an integer of 0 to 20, and R ⁴ in the case where q is 2 or more may be the same or different, and the (R ⁴ O) _q moiety is Random coupling or block coupling may be used. ]

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

-X < ² >-in General formula (2) is group represented by -O- or -NH-. Of these, a 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 a linear or branched alkylene group having 2 to 4 carbon atoms. Examples of the linear or branched alkylene group having 2 to 4 carbon atoms include ethylene group, isopropylene group, 1,2- or 1,3-propylene group, isobutylene group, and 1,2-, 1,3- or 1, 4-butylene group etc. are mentioned. Of these, ethylene group and 1,2-propylene group are preferable from the viewpoint of improving the viscosity index.

Q in the general formula (2) is an integer of 0 to 20, and is 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 and the low temperature viscosity.
A in the case where q is 2 or more may be the same or different, and the (R ⁴ O) _q moiety may be a random bond or a block bond.

R ⁵ and R ⁶ in the general formula (2) are each independently a linear alkyl group 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 An n-tetracosyl group may be mentioned.
Among linear alkyl groups having 8 to 24 carbon atoms, from the viewpoint of HTHS viscosity in the effective temperature range, linear alkyl groups having 8 to 20 carbon atoms are preferable, and linear chains having 9 to 18 carbon atoms are more preferable. An alkyl group, particularly preferably a linear alkyl group having 10 to 14 carbon atoms.

  Specific examples of the monomer (b) include 2-octyldecyl (meth) acrylate, an ester of ethylene glycol mono-2-octylpentadecyl ether and (meth) acrylic acid, and 2-octyl (meth) acrylate. Dodecyl, (meth) acrylic acid 2-decyltetradecyl, (meth) acrylic acid 2-dodecylhexadecyl, (meth) acrylic acid 2-tetradecyloctadecyl, (meth) acrylic acid 2-dodecylpentadecyl, (meth) acrylic 2-tetradecylheptadecyl acid, 2-hexadecylheptadecyl (meth) acrylate, 2-heptadecylicosyl (meth) acrylate, 2-hexadecyldocosyl (meth) acrylate, (meth) acrylic acid 2 -Eicosyl docosyl, 2-tetracosyl hexacosyl (meth) acrylate and N-2-octi Decyl (meth) acrylamide.

  Among the monomers (b), from the viewpoint of the HTHS viscosity in the effective temperature range, 2-octyldodecyl (meth) acrylate, 2-decyltetradecyl (meth) acrylate, (meth) acrylic acid 2- Dodecyl hexadecyl, 2-tetradecyl octadecyl (meth) acrylate.

  The (co) polymer (A) in the present invention has a monomer (c) represented by the general formula (3) and a linear alkyl group having 1 to 4 carbon atoms in addition to the monomer (a). A copolymer comprising at least one selected from the group consisting of (meth) acrylic acid alkyl ester (d) and (meth) acrylic acid alkyl ester (e) having a linear alkyl group having 12 to 36 carbon atoms as a constituent monomer. A polymer is preferable from the viewpoint of HTHS viscosity at an effective temperature.

[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 carbon number 1 A linear alkyl group of ˜8; r is an integer of 1-20, and when r is 2 or more, R ⁸ may be the same or different, and (R ⁸ O) _r moiety may be a random bond or a block bond Good. ]

R ⁹ in the general formula (3) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of the HTHS viscosity in the effective temperature range.

—X ³ — in the general formula (3) is a group represented by —O— or —NH—, and —X ³ — is preferably —O— from the viewpoint of the HTHS viscosity in the effective temperature range. It is group represented by these.

R ⁹ in the general formula (3) is a linear or branched alkylene group having 2 to 4 carbon atoms, and is an ethylene group, 1,2- or 1,3-propylene group, and 1,2-, 1,3- Or a 1, 4- butylene group is mentioned. Among these, ethylene group and 1,2-propylene group are preferable from the viewpoint of HTHS viscosity in the effective temperature range.

In the general formula (3), r is an integer of 1 to 20, preferably an integer of 1 to 16, more preferably an integer of 1 to 12, from the viewpoint of HTHS viscosity in the effective temperature range.
When R is 2 or more, R ⁸ 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, and is a methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n -A heptyl group and n-octyl group are mentioned. Of 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 HTHS viscosity in the effective temperature range, and more preferably 1 to 5 carbon atoms. It is a linear alkyl group.

Specific examples of the monomer (c) include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-n-propoxyethyl (meth) acrylate, (meth) acrylic acid 2 -N-butoxyethyl, 2-n-pentoxyethyl (meth) acrylate, 2-n-hexoxyethyl (meth) acrylate, 2-n-heptoxyethyl (meth) acrylate, 2-n- (meth) acrylate Examples include octoxyethyl, 2-n-ethoxyethyl (meth) acrylamide, 2-n-butoxyethyl (meth) acrylamide, 2-n-hexoxyethyl (meth) acrylamide, and 2-n-octoxyethyl (meth) acrylamide. It is done.
Among (c), from the viewpoint of the HTHS viscosity in the effective temperature range, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-n-propoxyethyl (meth) acrylate is preferable. , 2-n-butoxyethyl (meth) acrylate and 2-n-pentoxyethyl (meth) acrylate.

Examples of the (meth) acrylic acid alkyl ester (d) having a linear alkyl group having 1 to 4 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate and (meth) ) N-butyl acrylate.
Of (d), methyl (meth) acrylate and butyl (meth) acrylate are preferred, and butyl (meth) acrylate is particularly preferred.

Examples of the (meth) acrylic acid alkyl ester (e) having a linear alkyl group having 12 to 36 carbon atoms include n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n- (meth) acrylate. Tetradecyl, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, n-icosyl (meth) acrylate, n-tetracosyl (meth) acrylate, (meth) Examples include n-triacontyl acrylate and n-hexatriacontyl (meth) acrylate.
Of these, (d) is preferably a (meth) acrylic acid alkyl ester having a linear alkyl group having 12 to 32 carbon atoms, and more preferably a (meth) acrylic acid having a linear alkyl group having 16 to 30 carbon atoms. An ester, particularly preferably a (meth) acrylic acid ester having a linear alkyl group having 18 to 24 carbon atoms.

In addition to the monomers (a) to (e), the (co) polymer (A) in the present invention further contains a nitrogen atom-containing monomer (f), a hydroxyl group-containing monomer (g), and a phosphorus atom-containing monomer. From the viewpoint of the HTHS viscosity in the effective temperature range, a copolymer having at least one selected from the group consisting of the monomers (h) as a constituent monomer is preferable.
Examples of the nitrogen atom-containing monomer (f) include the following monomers (e1) to (e4) excluding the monomers (a), (b), and (c).

Amide group-containing monomer (f1):
(Meth) acrylamide, monoalkyl (meth) acrylamide [one having an 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 (Meth) acrylamide and Nn- or isobutyl (meth) acrylamide etc.], N- (N′-monoalkylaminoalkyl) (meth) acrylamide [one alkyl group having 1 to 4 carbon atoms bound 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 [nitrogen atom having two C1-C4 alkyl groups bonded; for example, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meta ) Acrylamide, N, N-diisopropyl (meth) acrylamide and N, N-di-n-butyl (meth) acrylamide etc.], N- (N ′, N′-dialkylaminoalkyl) (meth) acrylamide [aminoalkyl group Having an aminoalkyl group (2 to 6 carbon atoms) in which two alkyl groups having 1 to 4 carbon atoms are bonded to the nitrogen atom of, for example, N- (N ′, N′-dimethylaminoethyl) (meth) acrylamide, N- (N ′, N′-diethylaminoethyl) (meth) acrylamide, N- (N ′, N′-dimethylaminopropyl) (meth) acrylic And N- (N ′, N′-di-n-butylaminobutyl) (meth) acrylamide etc.]; N-vinylcarboxylic acid amide [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or Isopropionic acid amide, N-vinylhydroxyacetamide and the like] and the like.

Nitro group-containing monomer (f2):
4-nitrostyrene etc. are mentioned.

Monomer having a primary to tertiary amino group (f3):
Primary amino group-containing monomer {C3-C6 alkenylamine [(meth) allylamine, crotylamine, etc.], Aminoalkyl (C2-C6) (meth) acrylate [Aminoethyl (meth) acrylate, etc.}} Secondary amino group-containing 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; Nt-butylaminoethyl (meth) acrylate and N-methylaminoethyl (meth) acrylate, etc.], C6-C12 dialkenylamine [di (meth) allylamine, etc.]}; tertiary amino group-containing single amount Body {dialkylaminoalkyl (meth) acrylate [an aminoalkyl group in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom (carbon Having 2 to 6); for example, N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate, etc.], alicyclic (meth) acrylate having a nitrogen atom [morpholinoethyl ( Meth) acrylates, etc.], aromatic monomers [N- (N ′, N′-diphenylaminoethyl) (meth) acrylamide, N, N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N -Vinyl pyrrole, N-vinyl pyrrolidone, N-vinyl thiopyrrolidone, etc.]} and their hydrochlorides, sulfates, phosphates or lower alkyl (C1-8) monocarboxylic acids (such as acetic acid and propionic acid) Examples include salts.

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

  Of these, (f1) and (f3) are preferable, and N- (N ′, N′-diphenylaminoethyl) (meth) acrylamide and N- (N ′, N′-dimethyl) are more preferable. Aminoethyl) (meth) acrylamide, N- (N ′, N′-diethylaminoethyl) (meth) acrylamide, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide, N, N-dimethylaminoethyl (Meth) acrylate and N, N-diethylaminoethyl (meth) acrylate.

Hydroxyl-containing monomer (g):
Hydroxyl group-containing aromatic monomer (p-hydroxystyrene and the like), hydroxyalkyl (2 to 6 carbon atoms) (meth) acrylate [2-hydroxyethyl (meth) acrylate, and 2- or 3-hydroxypropyl (meth) acrylate Etc.], mono- or bis-hydroxyalkyl (C1-C4) 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 having 3 to 12 carbon atoms [(meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1 -Undecenol and the like], an alkene monool having 4 to 12 carbon atoms, Lucenediol [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (C1-6) alkenyl (C3-10) ether (2 -Hydroxyethylpropenyl ether, etc.), polyvalent (3-8 valent) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, saccharides, sucrose, etc.) alkenyl (3 to 10 carbon atoms) ether or (meth) acrylate [Sucrose (meth) allyl ether etc.] etc .;
Polyoxyalkylene glycol (alkylene group having 2 to 4 carbon atoms, polymerization degree 2 to 50), polyoxyalkylene polyol [polyoxyalkylene ether of 3 to 8 valent alcohol (alkylene group having 2 to 4 carbon atoms, polymerization degree) 2-100)], mono (meth) acrylates of polyoxyalkylene glycol or polyoxyalkylene polyol alkyl (carbon number 1-4) ether [polyethylene glycol (Mn: 100-300) mono (meth) acrylate, polypropylene glycol ( Mn: 130-500) mono (meth) acrylate, methoxypolyethylene glycol (Mn: 110-310) (meth) acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth) acrylate and mono (meth) acryl Polyoxyethylene (Mn: 150 to 230), sorbitan, etc.] or the like; and the like.

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

Phosphate group-containing monomer (h1):
(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) acryloyloxy” means acryloyloxy or methacryloyloxy.

Phosphono group-containing monomer (h2):
(Meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphonic acid [(meth) acryloyloxyethyl phosphonic acid etc.] and alkenyl (2 to 12 carbon atoms) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid and octenyl Phosphonic acid, etc.].

  (H) is preferably (h1), more preferably (meth) acryloyloxyalkyl (C2-4) phosphate ester, and particularly preferably (meth) acryloyloxyethyl phosphate.

  In addition to the monomers (a) to (h), (A) is a copolymer having a monomer (i) having two or more unsaturated groups as a constituent monomer. From the viewpoint of HTHS viscosity in the region.

  Examples of the monomer (i) having two or more unsaturated groups include divinylbenzene, alkadiene having 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene, and 1,7- Octadiene, etc.), (di) cyclopentadiene, vinylcyclohexene and ethylidenebicycloheptene, limonene, ethylene di (meth) acrylate, polyalkylene oxide glycol di (meth) acrylate, pentaerythritol triallyl ether, trimethylolpropane tri (meth) acrylate Examples thereof include esters of unsaturated carboxylic acids and glycols and esters of unsaturated alcohols and carboxylic acids described in International Publication No. WO 01/009242, and esters having Mn of 500 or more.

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

Aliphatic hydrocarbon monomer (j):
C2-C20 alkene (ethylene, propylene, butene, isobutene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.) etc. are mentioned.

Alicyclic hydrocarbon monomer (k):
Examples include cyclopentene, cyclohexene, cycloheptene, cyclooctene, and pinene.

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

Vinyl esters, vinyl ethers, vinyl ketones (m):
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 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, (meth) allyl chloride and halogenated styrene (dichlorostyrene and the like).

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

The proportion of (a) constituting (A) is preferably 1 to 50% by mass, more preferably 5 based on the weight of (A) from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range. It is -45 mass%, Most preferably, it is 8-30 mass%, Most preferably, it is 10-20 mass%.
The proportion of (b) constituting (A) is preferably 0 to 50% by mass, more preferably 0, based on the weight of (A), from the viewpoint of HTHS viscosity and low temperature viscosity in the effective temperature range. It is -45 mass%, Most preferably, it is 0-30 mass%.
The proportion of (c) constituting (A) is preferably 1 to 50% by mass, more preferably 5 based on the weight of (A) from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range. It is -45 mass%, Most preferably, it is 10-40 mass%.
The proportion of (d) constituting (A) is preferably 1 to 70% by mass, more preferably 5 based on the weight of (A) from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range. It is -70 mass%, Most preferably, it is 10-65 mass%, Most preferably, it is 45-65 mass%.
The proportion of (e) constituting (A) is preferably 1 to 40% by mass, more preferably 5 based on the weight of (A), from the viewpoints of HTHS viscosity and low temperature viscosity in the effective temperature range. It is -35 mass%, Most preferably, it is 10-30 mass%.
The total ratio of (a) to (e) constituting (A) is preferably 50 to 100% by mass based on the weight of (A) from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range. More preferably, it is 70-100 mass%, Most preferably, it is 80-100 mass%.
Each ratio of (f) to (h) constituting (A) is 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 mass%, More preferably, it is 1-12 mass%, Most preferably, it is 2-10 mass%.
The proportion of (i) constituting (A) is preferably from 0.01 to 200 ppm, more preferably from 0.05 to 200 ppm, based on the weight of (A), from the viewpoint of the HTHS viscosity in the effective temperature range. 50 ppm, particularly preferably 0.1 to 20 ppm.
Each ratio of (j) to (p) constituting (A) is preferably 0 to 10% by mass based on the weight of (A) from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. More preferably, it is 1-7 mass%, Most preferably, it is 2-5 mass%.

(A) SP value is 7.3-9.5 (cal / cm < ³ >) < ^1/2 >, From a viewpoint of the viscosity index improvement effect and the low temperature viscosity of a lubricating oil composition, Preferably it is 8.5-9. ^{.5 (cal / cm 3) 1/2} , more preferably ^{8.8~9.3 (cal / cm 3) 1/2} , particularly preferably ^{9.0~9.2 (cal / cm 3) 1} / ² .
The SP value of (A) is calculated based on the SP value of each monomer constituting (A) by the above method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (A) can be adjusted to 7.3 to 9.5 (cal / cm ³ ) ^1/2 by appropriately adjusting the SP value and molar fraction of the monomer used.

The absolute value (ΔSP) of the difference between the SP value of (A) and the SP value of the base oil is preferably 1.0 to 1.5 (cal / cm ³⁾ from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range. ) ^1/2 .

  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. 1 is the range. It is preferable to use it for applications having Mw of 200,000 to 2,000,000.

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

(A) can be obtained by a known production method, and specifically includes a method obtained by solution polymerization of the above monomer in a solvent in the presence of a polymerization catalyst.
Examples of the solvent include toluene, xylene, alkylbenzene having 9 to 10 carbon atoms, methyl ethyl ketone, and mineral oil.
Examples of the polymerization catalyst include azo catalysts (2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), etc.), peroxide catalysts (benzoylper Oxide, cumyl peroxide, lauryl peroxide, etc.) and redox catalysts (a mixture of benzoyl peroxide and tertiary amine, etc.). Furthermore, if necessary, a known chain transfer agent (such as an alkyl mercaptan having 2 to 20 carbon atoms) can also be used.
The polymerization temperature is preferably 25 to 140 ° C, more preferably 50 to 120 ° C. In addition to the above solution polymerization, (A) can be obtained by bulk polymerization, emulsion polymerization or suspension polymerization.
When (A) is a copolymer, the polymerization form may be either a random addition polymer or an alternating copolymer, and may be either a graft copolymer or a block copolymer.

The viscosity index improver of the present invention may be used in combination with (A) and an alkyl (meth) acrylate (co) polymer (B) other than (A).
(B) is not particularly limited as long as it is an alkyl (meth) acrylic acid ester (co) polymer other than (A), but a (meth) acrylic acid alkyl ester having a linear alkyl group having 1 to 18 carbon atoms. Examples include (co) polymers.
Specific examples of (B) include n-octadecyl methacrylate / n-dodecyl methacrylate (molar ratio 10-30 / 90-70) copolymer, n-tetradecyl methacrylate / n-dodecyl methacrylate (molar ratio 10). -30 / 90-70) Copolymer, n-hexadecyl methacrylate / n-dodecyl methacrylate / methyl methacrylate (molar ratio 20-40 / 55-75 / 0-10) copolymer and n-dodecyl acrylate / N-dodecyl methacrylate (molar ratio 10 to 40/90 to 60) copolymer and the like, and these may be used alone or in combination of two or more.

  When (A) and (B) are used in combination, the amount of (B) used is preferably 0.01 to 30% by mass, more preferably 0, based on the weight of (A), from the viewpoint of low temperature viscosity. 0.01 to 20% by mass, particularly preferably 0.01 to 10% by mass.

  The viscosity index improver composition of the present invention comprises the viscosity index improver of the present invention and a base oil. Base oils include mineral oils (solvent refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking isoparaffins, naphthenic oils, etc.), synthetic lubricating oils (hydrocarbon synthetic lubricating oils) (Poly α-olefin-based synthetic lubricating oil, etc.) and ester-based synthetic lubricating oil, etc.] and mixtures thereof. Of these, base oils that are API group II, base oils that are API group III, and base oils that are API group III +, more preferably mineral oils of API group II, mineral oils of API group III, and API groups III + mineral oil.

(Measured by JIS-K2283) kinematic viscosity at 100 ° C. of the base oil is preferably from the viewpoint of the HTHS viscosity at effective temperature is 1 to 10 mm ² / s, more preferably 1.5~8mm ² / s , and particularly preferably from 1.5~6mm ² / s, most preferably 2 to 6 mm ² / s.
The viscosity index (measured according to JIS-K2283) of the base oil is preferably 110 or more from the viewpoint of the HTHS viscosity in the effective temperature range.

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

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

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

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

<Production Example 1> Production of single-end hydroxyl group-containing (co) polymer 330 parts by weight of n-hexane was charged into a reactor and cooled to -40 ° C. To this was added 28 parts by weight of a cyclohexane solution of sec-butyllithium (concentration: 10.6% by mass), followed by 84 parts by weight of butadiene liquefied at -78 ° C. and stirring for 2 hours, followed by 18 parts by weight of tetrahydrofuran (THF). Part was added and stirred at −20 ° C. for 30 minutes. Further 1.5 hours later, 125 parts by weight of ethylene oxide (1.1 mol / l, THF solution) was added. The reaction solution was warmed to room temperature and stirred for 40 minutes, and then 122 parts by weight of methanol was added.
This solution was washed twice with 300 parts by weight of 0.3% by mass hydrochloric acid, and then twice with 300 parts by weight of pure water. 11 parts by weight of anhydrous magnesium sulfate was added to the organic layer and allowed to stand for 30 minutes. Filtration is performed, the filtrate is concentrated, the solvent is distilled off, and then a known hydrogenation treatment is performed to obtain 89 parts by weight of a highly viscous one-terminal hydroxyl group-containing (co) polymer (Y1-1). It was.
The physical properties of the obtained resin were as follows.
Total ratio of 1,2-butylene groups 68 mol%
Mn = 5,800, Mw / Mn = 1.07

<Production Example 2>
In Production Example 1, 28 parts by weight of a cyclohexane solution of sec-butyllithium (concentration is 10.6% by mass), a THF solution of t-butoxypotassium (concentration of t-butoxypotassium is 7.5% by mass, and the addition amount is A one-terminal hydroxyl group-containing (co) polymer (Y2-2) was obtained in the same manner except that the amount was changed to 80 parts by weight (2 mol of n-butyllithium).
The physical properties of the obtained resin were as follows.
Total ratio of isobutylene group and 1,2-butylene group 50 mol%
Mn = 7,300, Mw / Mn = 1.19

<Examples 1-6, Comparative Examples 1-2>
In a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen introduction tube, 200 parts by weight of the base oil described in Table 2, 100 parts by weight of the monomer blend described in Table 2, Charge 0.5 parts by weight of azobis (2,4-dimethylvaleronitrile) and 0.2 parts by weight of 2,2′-azobis (2-methylbutyronitrile) and perform nitrogen substitution (gas phase oxygen concentration 100 ppm). Then, the temperature was raised to 76 ° C. with stirring in a sealed state, and a polymerization reaction was performed at the same temperature for 4 hours. After raising the temperature to 120 to 130 ° C., the unreacted monomer was removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 2 hours, so that the concentrations shown in Table 2 were obtained so that the concentrations shown in Table 2 were obtained. Viscosity index improver compositions (R1) to (R6) and (S1) to (S2) containing copolymers (A1) to (A6) and (H1) to (H2) diluted with oil were obtained. SP values of the obtained copolymers (A1) to (A6) and (H1) to (H2) were calculated by the above method, and Mw was measured by the above method. Further, the kinematic viscosity of the viscosity index improver composition at 40 ° C., 80 ° C. and 100 ° C. was measured (JIS-K2283), and V1 and V2 were calculated. 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 appearance of the viscosity index improver compositions (R1) to (R6) and (S1) to (S2) was visually observed, and the base oil solubility was evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: Appearance is uniform and there is no insoluble matter in the copolymer ×: Appearance is inhomogeneous and insoluble matter in the copolymer is observed

<Evaluation method for handling (handling properties) under high temperature>
The handling properties of the viscosity index improver compositions (R1) to (R6) and (S1) to (S2) were evaluated according to the following evaluation criteria.
[Evaluation criteria]
Good: Kinematic viscosity (measured according to JIS-K2283) under atmospheric temperature (20 ° C) is 3,000 mm ² / s or less Impossible: Kinematic viscosity under atmospheric temperature (20 ° C) (measured according to JIS-K2283) Thing) exceeds 3,000 mm ² / s

The base oils listed in Table 2 are as follows.
Base oil A: YUBASE4 PLUS made by SK, SP value 8.10, 100 ° C. kinematic viscosity 4.16 mm ² / s, viscosity index 132 (API group III +)
Base oil B: YUBASE6 made by SK, SP value 8.10, kinematic viscosity at 100 ° C. 6.3 mm ² / s, viscosity index 130 (API group III)
Base oil C: YUBASE2, made by SK, SP value 8.10, kinematic viscosity at 100 ° C. 2.54 mm ² / s, viscosity index 100 (API group II)

The compositions of the monomers (a) to (g) described in Table 2 are as described below.
(A-1): Methacrylate ester of (Y1-1) (b-1): 2-n-decyltetradecyl methacrylate (c-1): 2-butoxyethyl methacrylate (c-2): methacryl 2-ethoxyethyl acid (d-1): butyl methacrylate (d-2): methyl methacrylate (e-1): n-dodecyl methacrylate (e-2): n-tetradecyl methacrylate (e-3) : N-hexadecyl methacrylate

<Examples 7 to 12 and Comparative Examples 3 to 4>
Viscosity index improver composition (R1) so that the base oil A is charged into a stainless steel container equipped with a stirrer and the HTHS viscosity at 150 ° C. is 2.60 ± 0.05 (mm ² / s). To (R6) and (S1) to (S2) were added to obtain lubricating oil compositions (T1) to (T6) and (W1) to (W2), respectively.
The shear stability, HTHS viscosity (80 ° C. and 100 ° C.), and low temperature viscosity (−40 ° C.) of the lubricating oil compositions (T1) to (T6) and (W1) to (W2) were measured by the following methods. Moreover, the kinematic viscosity of the viscosity index improver composition at 40 ° C. and 100 ° C. was measured (JIS-K2283), and the viscosity index was calculated. The results are shown in Table 3.

<Measurement method and calculation method of shear stability of lubricating oil composition>
Measured by ASTM D 6278 method and calculated by ASTM D 6022 method.

<Method for Measuring HTHS Viscosity of Lubricating Oil Composition>
Measurements were made at 80 ° C. and 100 ° C. by the method of ASTM D 5481.

<Method for Measuring Low Temperature Viscosity and Yield Stress of Lubricating Oil Composition>
Viscosity and yield stress at −40 ° C. were measured by the method of ASTM D 4684. Here, a yield stress of 35 Pa or less indicates no yield stress. Note that N. D indicates that measurement could not be performed.

  As is clear from the results in Table 3, the lubricating oil compositions (Examples 7 to 12) containing the viscosity index improver of the present invention are excellent in shear stability and have an HTHS viscosity in the effective temperature range. Low and low temperature viscosity is low. On the other hand, the lubricating oil composition of Comparative Example 3 has poor low temperature viscosity. The lubricating oil composition of Comparative Example 4 is inferior in HTHS viscosity in the effective temperature range.

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.), hydraulic oil (mechanical hydraulic oil, power steering oil, and shock). Absorber oil etc.), engine oil (gasoline and diesel etc.) and traction oil are suitable.

Claims (12)

A viscosity index improver composition comprising a polymer (A) having a monomer (a) represented by the general formula (1) as a constituent monomer and a base oil, and having a kinematic viscosity at 40 ° C. Viscosity index improver composition having a value (V1) obtained by dividing by a kinematic viscosity at 100 ° C. is in the range of 0.2-5.
[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 straight chain having 2 to 4 carbon atoms or a branched alkylene group, m is an integer of 0 to 20, a when m is 2 or more may be the same or different, (AO) _m moiety may be block also coupled with a random bond; R ² is A residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing isobutylene and / or 1,2-butylene as an essential constituent unit; p is a number of 0 or 1]   The viscosity index improver composition according to claim 1, wherein a value (V2) obtained by dividing the 80 ° C kinematic viscosity by the 100 ° C kinematic viscosity is in the range of 0.2 to 10. The base oil has a kinematic viscosity at 100 ° C. of 1 to 10 mm ² / s, and is at least one selected from the group consisting of a base oil that is API Group II, a base oil that is API Group III, and a base oil that is API Group III + The viscosity index improver composition according to claim 1, which is a base oil.   The viscosity index improver composition according to any one of claims 1 to 3, wherein the concentration of (A) is 15 to 30% by mass based on the mass of the viscosity index improver composition. The absolute value (ΔSP) of the difference between the SP value of (A) and the SP value of the base oil is 1.0 to 1.5 (cal / cm ³ ) ^1/2 . Viscosity index improver composition. (A) is a copolymer which uses the monomer (c) represented by General formula (3) as a structural monomer, The viscosity index improver composition in any one of Claims 1-5.
[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 carbon number 1 A linear alkyl group of ˜8; r is an integer of 1-20, and when r is 2 or more, R ⁸ may be the same or different, and (R ⁸ O) _r moiety may be a random bond or a block bond Good. ]   (A) is a (meth) acrylic acid alkyl ester (d) and / or a linear alkyl group having 12 to 36 carbon atoms, which further has a linear alkyl group having 1 to 4 carbon atoms as a constituent monomer of (A). The viscosity index improver composition according to any one of claims 1 to 6, which is a copolymer containing (meth) acrylic acid alkyl ester (e).   (A) is 1-50 mass%, (c) is 1-50 mass%, (d) is 1-70 mass%, and (d) based on the weight of (A) as a constituent monomer. The viscosity index improver composition according to claim 7, which is a copolymer containing 1 to 40% by mass of e). (A) is a copolymer which further contains the monomer (b) represented by General formula (2), The viscosity index improver composition in any one of Claims 1-8.
[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 Each independently a linear alkyl group having 8 to 24 carbon atoms; q is an integer of 0 to 20, and R ⁴ in the case where q is 2 or more may be the same or different, and the (R ⁴ O) _q moiety is Random coupling or block coupling may be used. ]   The viscosity index improver composition according to any one of claims 1 to 9, wherein the weight average molecular weight of (A) is 200,000 to 2,000,000.   The viscosity index improver composition according to any one of claims 1 to 10, wherein the base oil has a viscosity index of 110 or more.   The viscosity index improver composition according to any one of claims 1 to 11, a detergent, a dispersant, an antioxidant, an oil improver, a friction wear modifier, an extreme pressure agent, an antifoaming agent, an anti-emulsifier and corrosion. A lubricating oil composition comprising one or more additives selected from the group consisting of inhibitors.