JP2016065222A - Viscosity index improver composition and lubrication oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viscosity index improver that gives an excellent shear stability to a lubrication oil composition, gives a low HTHS viscosity to the lubrication oil composition, and hardly increases the low temperature viscosity of the lubrication oil composition.SOLUTION: Provided is a viscosity index improver composition comprising a base oil, and a (co)polymer (A) having a (meth)acrylate monomer comprising a branched alkyl group of 10 or more carbon atoms, as a constitutional unit, which contains the (co)polymer (A) whose degree of branching (CB) of the branched alkyl group in the (meth)acrylate monomer, derived from formula (1), satisfies the following formula (2) and formula (3) derived from an absolute value (ΔSP) of a solubility parameter difference between the solubility parameters of (A) and the base oil. (CB)=Σ[(BC)/(AC)×(BWT)]/(LCWT) (1), 0.83×(ΔSP)-0.75<(CB) (2), and 0.25≤(CB)<0.5 (3).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 (SAE J300). In the 0W-20 grade, the 150 ° C. HTHS viscosity (ASTM D4683 or D5481) under high temperature and high shear is Min. . It is specified in 2.6. In addition, 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 80 ° 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.

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

  An object of the present invention is to provide a viscosity index improver composition that is excellent in shear stability of a lubricating oil composition, has a low HTHS viscosity of the lubricating oil composition, and does not easily increase the low-temperature viscosity of the lubricating oil composition. .

As a result of intensive studies, the present inventor has reached the present invention. That is, the present invention relates to a viscosity index improver composition comprising a (co) polymer (A) having a (meth) acrylate monomer having a branched alkyl group having 10 or more carbon atoms as a structural unit and a base oil. From the absolute value (ΔSP) of the difference between the solubility parameter of (A) and the solubility parameter of the base oil, the degree of branching (CB) of the branched alkyl group of the (meth) acrylate monomer derived by the formula (1) A viscosity index improver composition comprising a (co) polymer (A) that satisfies the following formulas (2) and (3):
(CB) = Σ [(BC) / (AC) × (BWT)] / (LCWT) (1)
0.83 × (ΔSP) −0.75 <(CB) (2)
0.25 ≦ (CB) ≦ 0.5 (3)
BC: In each constituent monomer of the (meth) acrylate monomer, the number of carbon atoms in the branched alkyl group side chain AC: In each constituent monomer of the (meth) acrylate monomer, a branched alkyl group is added. Number of total carbon atoms constituting BWT: Weight ratio of each constituent monomer of (meth) acrylate monomer to weight of (A) (%)
LCWT: Weight ratio (%) of the total constituent monomers of the (meth) acrylate monomer to the weight of (A)

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

The viscosity index improver composition of the present invention is an improved viscosity index comprising a (co) polymer (A) having a (meth) acrylate monomer having a branched alkyl group having 10 or more carbon atoms as a constituent unit and a base oil. In the agent composition, the degree of branching (CB) of the branched alkyl group of the (meth) acrylate monomer derived by the following formula (1) is the difference between the solubility parameter of (A) and the solubility parameter of the base oil. A viscosity index improver composition comprising a (co) polymer (A) satisfying the following formulas (2) and (3) derived from an absolute value (ΔSP).
(CB) = Σ [(BC) / (AC) × (BWT)] / (LCWT) (1)
0.83 × (ΔSP) −0.75 <(CB) (2)
0.25 ≦ (CB) ≦ 0.5 (3)
BC: In each constituent monomer of the (meth) acrylate monomer, the number of carbon atoms in the branched alkyl group side chain AC: In each constituent monomer of the (meth) acrylate monomer, a branched alkyl group is added. Number of total carbon atoms constituting BWT: Weight ratio of each constituent monomer of (meth) acrylate monomer to weight of (A) (%)
LCWT: Weight ratio (%) of the total constituent monomers of the (meth) acrylate monomer to the weight of (A)
The branched alkyl group of the (meth) acrylate monomer has 10 or more carbon atoms, preferably from 10 to 2,000 carbon atoms from the viewpoint of shear stability and HTHS viscosity, and more preferably from 10 to 10 carbon atoms. 1,500, particularly preferably 10 to 1,000 carbon atoms.

  The (co) polymer (A) is preferably a monomer (a) represented by the general formula (1), a monomer (b) represented by the general formula (2), and the general formula (3). (Co) polymer having at least one monomer selected from the group of monomers (c) represented by

[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 an alkylene group having 2 to 4 carbon atoms. M is an integer of 0 to 20, and when m is 2 or more, A may be the same or different, and (AO) _m moiety may be a random bond or a block bond; R ² is 1,2- A residue obtained by removing one hydrogen atom from a hydrogenated polybutadiene having butylene as an essential constituent unit and a number average molecular weight of 1,000 or more; p is a number of 0 or 1. ]

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.

-X < ¹ >-in General formula (1) is group represented by -O-, -O (AO) _m-, or NH-.
A is an alkylene group having 2 to 4 carbon atoms.
Examples of the alkylene group having 2 to 4 carbon atoms include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3- or 1,4-butylene group.
m is an integer of 0 to 20, and preferably an integer of 0 to 4, more preferably an integer of 0 to 2, from the viewpoint of the HTHS viscosity in the effective temperature range.
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.
Of the —X ¹ —, a group represented by —O— and —O (AO) _m — is preferable from the viewpoint of the HTHS viscosity in the effective temperature range, and more preferably —O— and —O ( CH ₂ CH ₂ O) —.

  p is a number of 0 or 1.

R ² in the general formula (1) is obtained by removing one hydrogen atom from a hydrocarbon polymer having isobutylene and / or 1,2-butylene as an essential constituent unit (hereinafter abbreviated as “hydrocarbon polymer”). Residue.
Examples of the hydrocarbon polymer include polymers having the following (1) to (3) as constituent monomers in addition to isobutylene and / or 1,2-butylene.
The hydrocarbon polymer may be a block polymer or a random polymer.
(1) aliphatic unsaturated hydrocarbon [olefin having 2 to 36 carbon atoms (for example, ethylene, propylene, 2,3-butylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, triacocene, hexatriacocene, etc.) and C2-C36 dienes (for example, butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.)
(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 of isobutylene and / or 1,2-butylene is 30 mol% or more, more preferably 40 mol% or more, particularly preferably 50 mol% or more, Most preferably, it is 60 mol% or more.

  The monomer (a) represented by the general formula (1) is an ester of a hydroxyl group-containing (co) polymer (Y) having a hydroxyl group introduced at one end of a hydrocarbon polymer and (meth) acrylic acid. It can be obtained by a chemical reaction. “(Meth) acryl” means methacryl or acryl. “(Co) polymer” means a homopolymer or copolymer of monomers.

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) hydroboration reaction product of (co) polymer having a terminal double bond (for example, those described in US Pat. No. 4,316,973) and the like.
Maleic anhydride-ene-aminoalcohol adduct (Y3); imidation of a reaction product obtained by ene reaction of (co) polymer (x) having a terminal double bond and maleic anhydride with aminoalcohol And so on.
Hydroformyl-hydride (Y4); a product obtained by hydroformylating (co) polymer (x) having a terminal double bond and then hydrogenating (for example, those described in 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 1,000 or more, preferably 1,000 to 25,000 from the viewpoint of shear stability and HTHS viscosity, and more preferably 2, 000 to 20,000, particularly preferably 3,000 to 15,000, and most preferably 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 of (Y) and Mw of (A)>
Apparatus: “HLC-802A” [manufactured by Tosoh Corporation]
Column: Two “TSK gel GMH6” [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C.
Sample solution: 0.5 wt% tetrahydrofuran solution Solution injection amount: 200 μl
Detection device: Refractive index detector Reference material: Standard polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400) , 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

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

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.

As the (co) polymer (A) in the present invention, the monomer (b) represented by the general formula (2) can be used.
[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 is independently A linear alkyl group having 4 to 24 carbon atoms; q is an integer of 1 to 20, and when q is 2 or more, R ⁴ may be the same or different, and the (R ⁴ O) _q moiety may be a random bond Block combination may be used. ]

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

-X < ² >-in General formula (2) is group represented by -O- or -NH-. Among these, the group represented by —O— is preferable from the viewpoint of the effect of improving the viscosity index.

R 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 is mentioned.

Q in the general formula (2) is an integer of 1 to 20, preferably an integer of 1 to 5, more preferably an integer of 1 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 in the general formula (2) is each independently a linear alkyl group having 4 to 24 carbon atoms. Specifically, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, Examples include n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-eicosyl group, and n-tetracosyl group.
Of the linear alkyl groups having 8 to 24 carbon atoms, the linear alkyl group having 8 to 20 carbon atoms is preferable from the viewpoint of the HTHS viscosity in the effective temperature range, and more preferably 9 to 18 carbon atoms. Straight chain alkyl groups, particularly preferred are straight chain alkyl groups 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), preferred from the viewpoint of the HTHS viscosity in the effective temperature range are 2-octyldodecyl (meth) acrylate, 2-decyltetradecyl (meth) acrylate, (meth) acrylic acid 2 -Dodecylhexadecyl, 2-tetradecyloctadecyl (meth) acrylate.

  In the copolymer (A) in the present invention, the monomer (c) represented by the general formula (3) can be used as a constituent monomer.

[R ⁶ is a hydrogen atom or a methyl group; —X ³ — is a group represented by —O— or —NH—; R ⁷ is a hydrogen atom or a methyl group; — [CH (R ⁷ )] _n —CH ₃ Carbon number of the group represented is 14 to 40; n is an integer of ^{7 to} 38, n pieces of R ⁷ are each independently a hydrogen atom or a methyl group, and at least one of n pieces of R ⁷ Is a methyl group. ]

R ⁶ in the general formula (3) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of improving the viscosity index.

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

R ⁷ in the general formula (3) is a hydrogen atom or a methyl group.

Formula in _{^{(3) - [CH (R}} 7)] The number of carbon atoms of the groups represented by n -CH ₃ is 14 to 40. n is an integer of ^{7 to} 38, n R ^{7 s} are each independently a hydrogen atom or a methyl group, and at least one of n R ⁷ is a methyl group.

Specific examples of the monomer (c) include 1-methyltridecyl (meth) acrylate, 2-methyltridecyl (meth) acrylate, 3-methyltridecyl (meth) acrylate, and (meth) acrylic acid. 4-methyltridecyl, 5-methyltridecyl (meth) acrylate, 6-methyltridecyl (meth) acrylate, 7-methyltridecyl (meth) acrylate, 8-methyltridecyl (meth) acrylate, (Meth) acrylic acid 9-methyltridecyl, (meth) acrylic acid 10-methyltridecyl, (meth) acrylic acid 11-methyltridecyl, (meth) acrylic acid 1-methylheptadecyl, (meth) acrylic acid 2 -Methylheptadecyl, 3-methylheptadecyl (meth) acrylate, 4-methylheptadecyl (meth) acrylate, 5-methaacrylate (meth) acrylate Ruheptadecyl, 6-methylheptadecyl (meth) acrylate, 7-methylheptadecyl (meth) acrylate, 8-methylheptadecyl (meth) acrylate, 9-methylheptadecyl (meth) acrylate, (meth) acryl Acid 10-methylheptadecyl, (meth) acrylic acid 11-methylheptadecyl, (meth) acrylic acid 12-methylheptadecyl, (meth) acrylic acid 13-methylheptadecyl, (meth) acrylic acid 14-methylheptadecyl 15-methylheptadecyl (meth) acrylate, 1-methylheneicosyl (meth) acrylate, 2-methylheneicosyl (meth) acrylate, 3-methylheneicosyl (meth) acrylate, (meta ) 4-methylhenecosyl acrylate, 5-methylhenecosi (meth) acrylate 6-methylheneicosyl (meth) acrylate, 7-methylheneicosyl (meth) acrylate, 8-methylheneicosyl (meth) acrylate, 9-methylheneicosyl (meth) acrylate, ( (Meth) acrylic acid 10-methylheneicosyl, (meth) acrylic acid 11-methylheneicosyl, (meth) acrylic acid 12-methylheneicosyl, (meth) acrylic acid 13-methylheneicosyl, (meth) 14-methylhenecosyl acrylate, 15-methylheneicosyl (meth) acrylate, 17-methylheneicosyl (meth) acrylate, 19-methylheneicosyl (meth) acrylate, (meth) acrylic acid 1-methyltricosyl, 3-methyltricosyl (meth) acrylate, 5-methyltricosyl (meth) acrylate, 7-methyltricosyl (meth) acrylate, 9-methyltricosyl (meth) acrylate, 11-methyltricosyl (meth) acrylate, 13-methyltricosyl (meth) acrylate, (meth) acrylic 15 -Methyltricosyl, 17-methyltricosyl (meth) acrylate, 19-methyltricosyl (meth) acrylate, 21-methyltricosyl (meth) acrylate, and the like.
Among the monomers (c), from the viewpoint of HTHS viscosity in the effective temperature range, 11-methyltridecyl (meth) acrylate, 15-methylheptadecyl (meth) acrylate, and (meth) acrylic acid are preferable. 19-methylheneicosyl.

  The (co) polymer (A) in the present invention includes the monomer (d) represented by the general formula (4) and / or the number of carbon atoms in addition to the monomers (a), (b) and (c). A copolymer having a (meth) acrylic acid alkyl ester (e) having a linear alkyl group of 12 to 36 as a constituent monomer is preferable from the viewpoint of HTHS viscosity at an effective temperature.

[R ⁸ is a hydrogen atom or a methyl group; —X ⁴ — is a group represented by —O— or —NH—; R ⁹ is an alkylene group having 2 to 4 carbon atoms; R ¹⁰ is an alkyl having 1 to 6 carbon atoms; Group; r is an integer of 0 to 10, and R ⁹ when r is 2 or more may be the same or different, and the (R ⁹ O) _r moiety may be a random bond or a block bond. ]

R ⁸ in the general formula (4) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of improving the viscosity index.

-X ⁴ in the general formula (4) - is a group represented by -O- or -NH-. Among these, the group represented by —O— is preferable from the viewpoint of the effect of improving the viscosity index.

R ⁹ in the general formula (4) is an alkylene group having 2 to 4 carbon atoms. Examples of the 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. Is mentioned.

In the general formula (4), r is an integer of 0 to 10, and preferably an integer of 0 to 5, more preferably an integer of 0 to 2, most preferably from the viewpoint of the viscosity index improving effect and low temperature viscosity. Is 0 or 1.
A in the case where r is 2 or more may be the same or different, and the (R ⁹ O) _r moiety may be a random bond or a block bond.

R ¹⁰ in the general formula (4) is an alkyl group having 1 to 6 carbon atoms. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, n-heptyl, isoheptyl, and n-hexyl groups Can be mentioned.
Among the alkyl groups having 1 to 6 carbon atoms, the alkyl group having 1 to 5 carbon atoms is preferable from the viewpoint of the viscosity index, the alkyl group having 1 to 4 carbon atoms is more preferable, and the carbon number is particularly preferable. 4 alkyl groups.

As the monomer (d), methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and butyl (meth) acrylate, methoxyethyl (meth) acrylate, (meth) acrylic acid n-ethoxyethyl, n-propyloxyethyl (meth) acrylate, isopropyloxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, n-butoxy-1,2-propyl (meth) acrylate, Examples include (meth) acrylic acid n-butoxybutyl, isobutoxyethyl (meth) acrylate, and alcohols having 1 to 6 carbon atoms added with 1 to 10 moles of ethylene oxide to butylene oxide, and (meth) acrylic acid esters. It is done.
Among (d), preferred are methyl (meth) acrylate, butyl (meth) acrylate, and n-butoxyethyl (meth) acrylate, and particularly preferred are butyl (meth) acrylate and (meth) acrylic. The acid n-butoxyethyl.

Specific 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 (meth) acrylic. N-tetradecyl acid, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, n-icosyl (meth) acrylate, n-tetracosyl (meth) acrylate, Examples include (meth) acrylic acid n-triacontyl and (meth) acrylic acid n-hexatriacontyl.
Of these, (e) is preferably a (meth) acrylic acid alkyl ester having a linear alkyl group having 12 to 32 carbon atoms, and more preferably a (meth) having a linear alkyl group having 12 to 28 carbon atoms. Acrylic acid esters, particularly preferred are (meth) acrylic acid esters having a linear alkyl group having 12 to 22 carbon atoms.

The copolymer (A) in the present invention includes, in addition to the monomers (a) to (e), a nitrogen atom-containing monomer (excluding (a) to (d)) (f), a hydroxyl group-containing monomer One or more selected from the group consisting of a body (g), a phosphorus atom-containing monomer (h), a silicon atom-containing monomer (i), and a sulfur atom-containing monomer (j) are used as constituent monomers. A copolymer is preferred from the viewpoint of HTHS viscosity in the effective temperature range.
Examples of the nitrogen atom-containing monomer (f) include the following monomers (f1) to (f4) excluding the monomers (a), (b), (c), and (d).

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.

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

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, or 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) phosphate ester [(meth) acryloyloxyethyl phosphate in which one or two alkyl groups or alkylphenyl groups having 1 to 30 carbon atoms are bonded to phosphate ester , (Meth) acryloyloxyisopropyl phosphate, (meth) acryloyl-polyethylene glycol (r = 4-5) phosphate, (meth) acryloyl-polypropylene glycol (r = 5-6) sulfate, dimethyl- [2- (meth) Acryloyloxyethyl] phosphate, diethyl- [2- (meth) acryloyloxyethyl] phosphate and diphenyl- [2- (meth) acryloyloxyethyl] phosphate] and phosphoric acid alkenyl esters [vinyl phosphate, allyl phosphate, phosphoric acid] Propenyl, phosphoric acid Sopuropeniru, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, and phosphoric acid dodecenyl, etc.] and the like. “(Meth) acryloyloxy” means acryloyloxy or methacryloyloxy.

Phosphono group-containing monomer (h2):
(Meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphonic acid [(meth) acryloyloxyethylphosphonic acid in which one or two alkyl groups or alkylphenyl groups having 1 to 30 carbon atoms are bonded to phosphonic acid, etc. And alkenyl (having 2 to 12 carbon atoms) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid, octenyl phosphonic acid, dimethyl vinyl phosphonate, diethyl vinyl phosphonate, diphenyl vinyl phosphonate, and the like].

  Among (h), (h1) is preferable, (meth) acryloyloxyalkyl (2 to 4 carbon atoms) phosphate is more preferable, and (meth) acryloyloxyethyl phosphate is particularly preferable. And diphenyl- [2- (meth) acryloyloxyethyl] phosphate.

  Silicon atom-containing monomer (i): (meth) acryloyloxyalkyl (2 to 4 carbon atoms) alkoxysilyl [3-methacryloxypropylmethyldimethylsilane, 3-methacryloxypropyltrimethylsilane, 3-methacryloxypropylmethyl Diethyl silane, 3-methacryloxypropyl triethyl silane, etc.].

  Sulfur atom-containing monomer (j): (meth) acryloyloxyalkyl (2 to 4 carbon atoms) poly (alkylthioether) alkyl [2-methacryloxyethylpoly (ethylenethioether) methyl, 2-methacryloxyethylpoly ( Ethylenethioether) ethyl and the like].

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

  Examples of the monomer (k) 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 And an ester of an unsaturated carboxylic acid and a glycol having an Mn of 500 or more and an ester of an unsaturated alcohol and a carboxylic acid described in International Publication WO01 / 009242.

  In (A), in addition to the monomers (a) to (k), the following monomers (l) to (r) may be used as constituent monomers.

Aliphatic hydrocarbon monomer (l):
C2-C20 alkene (Ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.) etc. are mentioned.

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

Aromatic hydrocarbon monomer (n):
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 (o):
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 (p):
Examples thereof include glycidyl (meth) acrylate and glycidyl (meth) allyl ether.

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

Unsaturated polycarboxylic acid ester (r):
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 weight, more preferably 5 to 50% by weight, based on the weight of (A), from the viewpoint of the HTHS viscosity in the effective temperature range. %, Particularly preferably 8 to 40% by weight, most preferably 10 to 30% by weight.
The proportion of (b) constituting (A) is preferably 1 to 60% by weight, more preferably 5 to 60% by weight, based on the weight of (A), from the viewpoint of the HTHS viscosity in the effective temperature range. %, Particularly preferably 10 to 55% by weight, most preferably 10 to 50% by weight.
The proportion of (c) constituting (A) is preferably 0 to 50% by weight, more preferably 1 to 40% by weight, based on the weight of (A), from the viewpoint of the HTHS viscosity in the effective temperature range. Particularly preferred is 1 to 30% by weight, and most preferred is 1 to 20% by weight.
The proportion of (d) constituting (A) is preferably 1 to 70% by weight, more preferably 5 to 65% by weight based on the weight of (A), from the viewpoint of the HTHS viscosity in the effective temperature range. %, Particularly preferably 10 to 60% by weight, most preferably 20 to 50% by weight.
The sum of the proportions of (a), (b), (c) and (d) constituting (A) is preferably about the lower limit based on the weight of (A) from the viewpoint of the HTHS viscosity in the effective temperature range. Is 5% by weight, more preferably 30% by weight, particularly preferably 40% by weight, and the upper limit is preferably 95% by weight, more preferably 90% by weight, particularly preferably 88% by weight.
The proportion of (e) constituting (A) is preferably 1 to 40% by weight based on the weight of (A) from the viewpoint of the HTHS viscosity in the effective temperature range and the low temperature viscosity of the lubricating oil composition. More preferably, it is 1 to 30% by weight, particularly preferably 1 to 25% by weight.
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% by weight, more preferably 1 to 12% by weight, and particularly preferably 2 to 10% by weight.
The proportion of (i) constituting (A) is preferably 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 (r) constituting (A) is preferably 0 to 10% by weight based on the weight of (A) from the viewpoint of the effect of improving the viscosity index and the low temperature viscosity of the lubricating oil composition. More preferably, it is 1 to 7% by weight, particularly preferably 2 to 5% by weight.

The degree of branching (CB) of the branched alkyl group of the (meth) acrylate monomer can be calculated by the following formula (1).
(CB) = Σ [(BC) / (AC) × (BWT)] / (LCWT) (1)
BC: In each constituent monomer of the (meth) acrylate monomer, the number of carbon atoms in the branched alkyl group side chain AC: In each constituent monomer of the (meth) acrylate monomer, a branched alkyl group is added. Number of total carbon atoms constituting BWT: Weight ratio of each constituent monomer of (meth) acrylate monomer to weight of (A) (%)
LCWT: Total weight ratio of each constituent monomer of the (meth) acrylate monomer to the weight of (A) (%)

  The number of carbon atoms in the branched alkyl group side chain is a number obtained by subtracting the number of carbon atoms in the branched alkyl group main chain from the number of all carbon atoms constituting the branched alkyl group. The main chain is a carbon chain selected so as to maximize the chain length, and the number of carbon atoms in the carbon chain is the number of carbon atoms in the main chain. The side chain carbon atoms are carbon atoms other than the main chain carbon atoms. When there are two or more side chains, the number of carbon atoms in the side chain is the total number of carbon atoms in each side chain. In addition, when there are two or more carbon chains selected so as to maximize the chain length, one of them is defined as the main chain.

  Here, (BC) is, for example, a 2-decylhexadecyl group in which the number of all carbon atoms constituting the branched alkyl group is 24, and has a branched structure at the 2-position, and the carbon atom of the branched alkyl group main chain The number of is 14. The number of carbon atoms in the other branched alkyl group side chain is 10 since it is 10 from the 2nd branch. Moreover, in the hexamethyldodecyl group in which the number of all carbon atoms constituting the branched alkyl group is 18, the number of carbon atoms in the branched alkyl group main chain is 12, and the number of methyl groups in the branched side chain is 6 Therefore, the number of carbon atoms in the branched alkyl group side chain is 6.

In (A), the relationship between CB and ΔSP satisfies the following relational expression (2).
0.83 × (ΔSP) −0.75 <(CB) (2)

The SP value of (A) is 7.3 to 9.5 (cal / cm ³ ) ^1/2 , and is preferably 8.5 to 8.5 from the viewpoint of improving the viscosity index and solubility in the lubricating oil composition. 9.5 (cal / cm ³ ) ^1/2 , more preferably 8.8 to 9.4 (cal / cm ³ ) ^1/2 , and particularly preferably 8.9 to 9.3 (cal / cm ³ ) ^{1 / 2} .
The SP value of (A) is calculated based on the SP value of each monomer constituting (A) by the above method, and the SP value of each monomer is based on the mole fraction of the constituent monomer units. The average value.
The SP value of (A) can be adjusted to 7.3 to 9.5 (cal / cm ³ ) ^1/2 by appropriately adjusting the SP value and molar fraction of the monomer used.

(A) and ΔSP of the base oil are preferably 1.1 to 1.5 (cal / cm ³ ) ^1/2 from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range, and more preferably 1. ^{1~1.4 (cal / cm 3) 1/2} , particularly preferably ^{1.1~1.3 (cal / cm 3) 1/2} .

(CB) in (A) satisfies the following formula (3).
0.25 ≦ (CB) ≦ 0.5 (3)
(CB) in (A) is preferably 0.25 to 0.40 from the viewpoint of the HTHS viscosity and the low temperature viscosity in the effective temperature range.

(A) is preferably dissolved in a base oil of API group III having a kinematic viscosity at 100 ° C. of 4 to 6 mm ² / s. Here, dissolution means that 100 parts by weight of (A) is dissolved in 400 parts by weight of base oil, the appearance is uniform, and there is no insoluble matter of (A).

  (A) is a spectrum obtained by nuclear magnetic resonance analysis (13C-NMR), wherein the peak total area M1 between the chemical shift 29-31 ppm relative to the total area of all peaks and the peak between the chemical shift 67-73 ppm. The ratio M1 / M2 of the total area M2 is 1.0 or more.

  M1 / M2 needs to be 1.0 or more, preferably 2.0 or more, more preferably 3.0 or more, particularly preferably 4.0 or more, and most preferably 5.0 or more. M1 / M2 is preferably 20 or less, more preferably 18 or less, particularly preferably 16 or less, and most preferably 14 or less. When M1 / M2 is less than 1.0, the required fuel economy cannot be obtained, and the low-temperature viscosity characteristics may be deteriorated. On the other hand, when M1 / M2 exceeds 14, the required fuel economy may not be obtained, and the solubility and storage stability may be deteriorated.

  (A) is a spectrum obtained by nuclear magnetic resonance analysis (13C-NMR), wherein the peak total area M3 between the chemical shift 10-20 ppm relative to the total area of all peaks and the peak between the chemical shift 25-35 ppm. The ratio M3 / M4 of the total area M4 is 0.20 or more.

  M3 / M4 needs to be 0.20 or more, preferably 0.3 or more, more preferably 0.4 or more, particularly preferably 0.5 or more, and most preferably 0.6 or more. M3 / M4 is preferably 5.0 or less, more preferably 3.0 or less, particularly preferably 2.0 or less, and most preferably 1.5 or less. When M3 / M4 is less than 0.20, not only the required fuel saving performance is not obtained, but also the low-temperature viscosity characteristics may be deteriorated. Moreover, when M3 / M4 exceeds 5.0, there exists a possibility that the required fuel-saving property may not be acquired, and there exists a possibility that solubility and storage stability may deteriorate.

  (A) is a spectrum obtained by nuclear magnetic resonance analysis (13C-NMR), wherein the peak total area M5 between the chemical shift 44-46 ppm relative to the total area of all peaks and the peak between the chemical shift 63-72 ppm. The ratio M5 / M6 of the total area M6 is 0.20 or more.

  M5 / M6 needs to be 0.20 or more, preferably 0.3 or more, more preferably 0.4 or more, particularly preferably 0.5 or more, and most preferably 0.6 or more. M5 / M6 is preferably 3.0 or less, more preferably 2.0 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. When M5 / M6 is less than 0.20, not only the required fuel economy is not obtained, but also the low-temperature viscosity characteristics may be deteriorated. Moreover, when M5 / M6 exceeds 3.0, there exists a possibility that the required fuel-saving property may not be acquired, and there exists a possibility that solubility and storage stability may deteriorate.

  The nuclear magnetic resonance analysis (13C-NMR) spectrum is obtained from a polymer obtained by separating the diluent oil by rubber membrane dialysis or the like when the diluent oil is contained in (A).

In addition, the total area (M1) of the peak between the chemical shifts 29-31 ppm with respect to the total area of all the peaks is the side chain of the poly (meth) acrylate with respect to the total integrated intensity of all the carbons measured by 13C-NMR. It means the proportion of integrated intensity derived from a specific ethylene structure. The total area (M2) of the peak between chemical shifts 67-73 ppm relative to the total area of all peaks is the specific ether of the poly (meth) acrylate side chain relative to the total integrated intensity of all carbons, as measured by 13C-NMR. It means the ratio of integral intensity derived from the structure.
The total peak area (M3) between 10-20 ppm chemical shift relative to the total area of all peaks is the specific methyl of the poly (meth) acrylate side chain relative to the total integrated intensity of all carbons, as measured by 13C-NMR. It means the ratio of integral intensity derived from the structure.
The total peak area (M4) between 25-35 ppm chemical shift relative to the total area of all peaks is the specific methylene of the poly (meth) acrylate side chain relative to the total integrated carbon total intensity, as measured by 13C-NMR. It means the ratio of integral intensity derived from the structure.
The total peak area (M5) between 44-46 ppm chemical shift relative to the total area of all peaks is the specific methine of the poly (meth) acrylate side chain relative to the total integrated carbon total intensity as measured by 13C-NMR. It means the ratio of integral intensity derived from the structure.
The total area of the peak (M5) between chemical shifts 63-72 ppm relative to the total area of all peaks is the oxygen atom of the poly (meth) acrylate side chain relative to the total integrated intensity of all carbons, as measured by 13C-NMR. It means the ratio of integrated intensity derived from adjacent carbon atoms.

  M1 / M2 means the ratio of the specific methylene structure and the specific ether structure of the poly (meth) acrylate side chain, but other methods may be used as long as equivalent results are obtained. In the 13C-NMR measurement, 0.1 g of a sample diluted with 2 ml of deuterated chloroform was used as a sample, the measurement temperature was room temperature, the resonance frequency was 100 MHz, and the measurement method was a decoupling method with a reverse gate. It was used.

From the above analysis,
(A) Sum of integral intensities with chemical shifts of about 10-74 ppm (sum of integral intensities due to total carbon of hydrocarbons), and (b) Sum of integral intensities with chemical shifts of 29-31 ppm (for specific β-branch structures) Sum of integral intensities resulting from), and (c) sum of integral intensities of chemical shifts 67-73 ppm (sum of integral intensities due to specific linear structures)
(D) Sum of integral intensities with chemical shift of 10-20 ppm (sum of integral intensities resulting from specific β-branch structure), and (e) Sum of integral intensities of chemical shifts of 29-31 ppm (with particular linear structure) Sum of integral intensities)
(F) Sum of integral intensities with chemical shifts 44-46 ppm (sum of integral intensities due to specific β-branch structure), and (g) Sum of integral intensities with chemical shifts of 63-72 ppm (because of specific linear structure) Sum of integral intensities)
Were measured, and the ratio (%) of (b) when (a) was set to 100% was calculated as M1. Similarly, the ratio (%) of (c), (d), (e), (f), and (g) when (a) is set to 100% is calculated, and M2, M3, M4, M5, M6.

  The shear stability index of (A) is preferably 50 or less, more preferably 40 or less, still more preferably 35 or less, and particularly preferably 30 or less. Moreover, it is preferable that it is 5 or more, More preferably, it is 10 or more, More preferably, it is 15 or more, Most preferably, it is 20 or more. When the shear stability index is less than 5, the viscosity index improvement effect is small and the cost may increase, and when the shear stability index exceeds 50, the shear stability and storage stability may be deteriorated.

  Mw of (A) is preferably 100,000 or more, more preferably 200,000 or more, particularly preferably 250,000 or more, and most preferably 300,000 or more. Further, it is preferably 1,000,000 or less, more preferably 700,000 or less, particularly preferably 600,000 or less, and most preferably 500,000 or less. If the Mw is less than 100,000, the effect of improving the viscosity temperature characteristic and the effect of improving the viscosity index are small and the cost may increase. If the Mw exceeds 1,000,000, the shear stability and the base oil may be increased. There is a possibility that the solubility and storage stability of the resin may deteriorate.

  Mn in (A) is preferably 50,000 or more, more preferably 80,000 or more, particularly preferably 100,000 or more, and most preferably 120,000 or more. Further, it is preferably 500,000 or less, more preferably 300,000 or less, particularly preferably 250,000 or less, and most preferably 200,000 or less. When Mn is less than 50,000, the effect of improving the viscosity temperature characteristics and the effect of improving the viscosity index are small and the cost may increase. When Mn exceeds 500,000, the shear stability and dissolution in the base oil are likely to occur. And storage stability may be deteriorated.

The ratio (Mw / PSSI) of Mw and PSSI in (A) is preferably 0.8 × 10 ⁴ or more, preferably 1.0 × 10 ⁴ or more, more preferably 1.5 × 10 ⁴ or more, More preferably, it is 1.8 × 10 ⁴ or more, and particularly preferably 2.0 × 10 ⁴ or more. When Mw / PSSI is less than 0.8 × 10 ⁴ , the viscosity temperature characteristic may be deteriorated, that is, the fuel economy may be deteriorated.

  The ratio (Mw / Mn) of Mw and Mn in (A) is preferably 0.5 or more, preferably 1.0 or more, more preferably 1.5 or more, still more preferably 2.0 or more, particularly Preferably it is 2.1 or more. Further, Mw / Mn is preferably 6.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and particularly preferably 3.0 or less. When Mw / Mn is less than 0.5 or exceeds 6.0, the viscosity temperature characteristic may be deteriorated, that is, the fuel economy may be deteriorated.

(A) kinematic viscosity at 40 ° C. and kinematic viscosity at 100 ° C. ΔKV40 / ΔKV100 is preferably 4.0 or less, more preferably 3.5 or less, still more preferably 3.0 or less. Particularly preferred is 2.5 or less, and most preferred is 2.3 or less. Further, ΔKV40 / ΔKV100 is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.5 or more, and particularly preferably 2.0 or more.
If ΔKV40 / ΔKV100 is less than 0.5, the effect of increasing viscosity and solubility may be small and the cost may increase. If it exceeds 4.0, the effect of improving viscosity temperature characteristics and low temperature viscosity characteristics may be obtained. May be inferior.

  Here, ΔKV40 means an increase in kinematic viscosity at 40 ° C. when 1.0% of (co) polymer (A) is added to SK Corporation YUBASE4, and ΔKV100 is SK Corporation YUBASE4 (both). It means an increase in kinematic viscosity at 100 ° C. when 1.0% of the polymer (A) is added.

  The (A) HTHS viscosity at 100 ° C. and HTHS viscosity at 150 ° C. ΔTHHS100 / ΔHTHS150 is preferably 2.0 or less, more preferably 1.7 or less, still more preferably 1.6 or less, Especially preferably, it is 1.55 or less. ΔHTHS100 / ΔHTHS150 is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.2 or more, and particularly preferably 1.4 or more. If ΔHTHS100 / ΔHTHS150 is less than 0.5, the effect of increasing viscosity and solubility may be small and the cost may increase, and if it exceeds 2.0, the effect of improving viscosity temperature characteristics and low temperature viscosity characteristics may be obtained. May be inferior.

  Here, ΔHTHS100 means an increase in HTHS viscosity at 100 ° C. when 1.0% of (co) polymer (A) is added to SK YUBASE4, and ΔHTHS150 is SKBASE YUBASE4 (co). It means an increase in HTHS viscosity at 150 ° C. when 1.0% of the polymer (A) is added. ΔHTHS100 / ΔHTHS150 means the ratio of the increase in HTHS viscosity at 100 ° C. to the increase in HTHS viscosity at 150 ° C. The HTHS viscosity at 100 ° C. here refers to a high-temperature high-shear viscosity at 100 ° C. as defined in ASTM D4683. Further, the HTHS viscosity at 150 ° C. means a high temperature high shear viscosity at 150 ° C. as defined in ASTM D4683.

  The content of (A) in the lubricating oil composition of the present invention is preferably 0.01 to 25% by mass, more preferably 0.2 to 20% by mass, and still more preferably based on the total amount of the lubricating oil composition. It is 0.5-15 mass%, Most preferably, it is 1-10 mass%. When the content of (A) is less than 0.01% by mass, the effect of improving the viscosity index and the effect of reducing the product viscosity are diminished, and thus there is a possibility that the fuel economy cannot be improved. On the other hand, if the amount exceeds 50% by mass, the product cost is significantly increased and the HTHS viscosity is decreased.

Kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably from 4 to 12 mm ² / s, more preferably 4.5 mm ² / s or more as a lower limit, more preferably ^{5 mm} 2 / s or more, Especially preferably, it is 6 mm < ² > / s or more, Most preferably, it is 7 mm < ² > / s or more. The upper limit is preferably 11 mm ² / s or less, more preferably 10 mm ² / s or less, particularly preferably 9 mm ² / s or less, and most preferably 8 mm ² / s or less. If the kinematic viscosity at 100 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 12 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

(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 weight and more preferably 0 based on the weight of (A) from the viewpoint of low temperature viscosity. 0.01 to 20% by weight, particularly preferably 0.01 to 10% by weight.

In the lubricating oil composition of the present invention, a lubricating base oil having a kinematic viscosity at 100 ° C. of 1 to 10 mm ² / s can be used.
The lubricating base oil according to the present invention is not particularly limited as long as the kinematic viscosity at 100 ° C. satisfies the above conditions. Specifically, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and / or vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid Among paraffinic mineral oils, normal paraffinic base oils, isoparaffinic base oils, etc. purified by combining one or more of purification processes such as washing and clay treatment alone or in combination, have a kinematic viscosity at 100 ° C. A base oil that satisfies the above conditions can be used.

  A preferred example of the lubricating base oil according to the present invention is obtained by refining a raw oil and / or a lubricating oil fraction recovered from the raw oil by a predetermined refining method and recovering the lubricating oil fraction. Can be mentioned.

  The above-mentioned predetermined purification methods include hydrorefining such as hydrocracking and hydrofinishing; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; acid clay and activated clay White clay refining; chemical (acid or alkali) cleaning such as sulfuric acid cleaning and caustic soda cleaning are preferred. In the present invention, one of these purification methods may be performed alone, or two or more may be combined. Moreover, when combining 2 or more types of purification methods, the order in particular is not restrict | limited, It can select suitably.

  Further, the catalyst used for the hydrocracking is not particularly limited, but a binder comprising a composite oxide having cracking activity (for example, silica alumina, alumina boria, silica zirconia, etc.) or a combination of one or more of the composite oxides. A hydrocracking catalyst in which a metal having a hydrogenation ability (for example, one or more metals such as Group VIa metal and Group VIII metal in the periodic table) supported on a carrier bonded with a catalyst is used, or zeolite ( For example, a hydroisomerization catalyst in which a metal having a hydrogenation ability including at least one of Group VIII metals is supported on a support including ZSM-5, zeolite beta, SAPO-11, etc. is preferably used. . The hydrocracking catalyst and the hydroisomerization catalyst may be used in combination by stacking or mixing.

The 100 ° C. kinematic viscosity of the lubricating base oil according to the present invention needs to be 10 mm ² / s or less, preferably 9 mm ² / s or less, more preferably 7 mm ² / s or less, and still more preferably 5. It is 0 mm ² / s or less, particularly preferably 4.5 mm ² / s or less, and most preferably 4.0 mm ² / s or less. On the other hand, the 100 ° C. kinematic viscosity needs to be 1 mm ² / s or more, preferably 1.5 mm ² / s or more, more preferably 2 mm ² / s or more, and further preferably 2.5 mm. ² / s or more, particularly preferably 3 mm ² / s or more. The kinematic viscosity at 100 ° C. here refers to the kinematic viscosity at 100 ° C. as defined in ASTM D-445. If the 100 ° C. kinematic viscosity of the lubricating base oil component exceeds 10 mm 2 / ^s, the worse the low temperature viscosity characteristics, also does not provide a sufficient fuel economy, the following cases 1 mm 2 / ^s at lubricating sites Insufficient oil film formation results in poor lubricity and increases the evaporation loss of the lubricating oil composition.

Further, the kinematic viscosity at 40 ° C. of the lubricating base oil according to the present invention is preferably 80 mm ² / s or less, more preferably 50 mm ² / s or less, still more preferably 20 mm ² / s or less, and particularly preferably 18 mm ² / s. s or less, most preferably 16 mm ² / s or less. On the other hand, the 40 ° C. kinematic viscosity is preferably 6.0 mm ² / s or more, more preferably 8.0 mm ² / s or more, further preferably 12 mm ² / s or more, and particularly preferably 14 mm ² / s or more. Most preferably, it is 15 mm ² / s or more. When the 40 ° C. kinematic viscosity of the lubricating base oil component exceeds 80 mm ² / s, the low-temperature viscosity characteristics deteriorate, and sufficient fuel economy cannot be obtained. When the lubricating base oil component is 6.0 mm ² / s or less, lubrication occurs. Insufficient oil film formation at the locations results in poor lubricity and increases the evaporation loss of the lubricating oil composition.

  The viscosity index of the lubricating base oil according to the present invention is preferably 120 or more. More preferably, it is 120-180, More preferably, it is 120-160. When the viscosity index is less than the lower limit, the heat / oxidation stability, volatilization prevention property and friction coefficient tend to increase. On the other hand, when the viscosity index exceeds the upper limit, the low-temperature viscosity characteristics tend to decrease.

  In addition, the viscosity index as used in the field of this invention means the viscosity index based on ASTM D-2270.

Further, the density (ρ15) at 15 ° C. of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil component, but is not more than the value of ρ represented by the following formula (A), that is, ρ15. It is preferable that ≦ ρ.
ρ = 0.0025 × kv100 + 0.816 (A)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil component at 100 ° C. ]

  When ρ15> ρ, the viscosity-temperature characteristics and thermal / oxidation stability, as well as the volatilization prevention properties and low-temperature viscosity characteristics tend to be lowered, which may deteriorate fuel economy.

  Specifically, the density (ρ15) at 15 ° C. of the lubricating base oil according to the present invention is preferably 0.860 or less, more preferably 0.850 or less, still more preferably 0.840 or less, and particularly preferably 0. .822 or less.

  In addition, the density in 15 degreeC said by this invention means the density measured in 15 degreeC based on JISK2249-1: 2011.

  Further, the pour point of the lubricating base oil according to the present invention is preferably −10 ° C. or lower, more preferably −12.5 ° C. or lower, and further preferably −15 ° C. or lower. When the pour point exceeds the upper limit, the low temperature fluidity of the entire lubricating oil tends to be reduced. In addition, the pour point as used in the field of this invention means the pour point measured based on JISK2269: 1987.

Further, the aniline point (AP (° C.)) of the lubricating base oil according to the present invention is preferably not less than the value of A represented by the following formula (B), that is, AP ≧ A.
A = 4.3 × kv100 + 100 (B)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil at 100 ° C. ]

  When AP <A, thermal / oxidative stability, volatilization prevention properties and low-temperature viscosity characteristics tend to decrease, and when an additive is added to the lubricating base oil, the additive The effect tends to decrease. In addition, the aniline point as used in the field of this invention means the aniline point measured based on JISK2256: 2013.

  The iodine value of the lubricating base oil according to the present invention is preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, particularly preferably 0.9 or less, and most preferably 0.8. It is as follows. Moreover, from the relationship with economy, it is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.03 or more, and particularly preferably 0.05 or more. By setting the iodine value of the lubricating base oil component to 3 or less, the thermal and oxidation stability can be improved. In addition, the iodine value as used in the field of this invention means the iodine value measured by the indicator titration method of JISK0070: 1992.

  Further, the sulfur content in the lubricating base oil according to the present invention is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, and even more preferably 10 mass ppm or less, It is particularly preferably 5 ppm by mass or less.

  Further, the content of nitrogen in the lubricating base oil according to the present invention is preferably 7 ppm by mass or less, more preferably 5 ppm by mass or less, and even more preferably 3 ppm by mass or less. If the nitrogen content exceeds 5 ppm by mass, the thermal and oxidation stability tends to decrease. In addition, the nitrogen content as used in the field of this invention means the nitrogen content measured based on JISK2609: 1998.

  Further, the% CA of the lubricating base oil according to the present invention needs to be 5 or less, more preferably 2 or less, still more preferably 1 or less, and particularly preferably 0.5 or less. When the% CA of the lubricating base oil exceeds the upper limit, the thermal / oxidation stability and the frictional characteristics tend to deteriorate.

  The% Cp of the lubricating base oil according to the present invention is preferably 70 or more, preferably 80 to 99, more preferably 85 to 95, still more preferably 87 to 94, particularly preferably 90 to 94. is there. When the% Cp of the lubricating base oil is less than the lower limit, the thermal / oxidation stability and the friction characteristics tend to be lowered. Moreover, when% Cp of lubricating base oil exceeds the said upper limit, it exists in the tendency for the solubility of an additive to fall.

  The% CN of the lubricating base oil according to the present invention is preferably 30 or less, more preferably 4 to 25, still more preferably 5 to 13, and particularly preferably 5 to 8. When the% CN of the lubricating base oil exceeds the upper limit, the thermal / oxidative stability and the friction characteristics tend to be lowered. Moreover, when% CN is less than the said lower limit, it exists in the tendency for the solubility of an additive to fall.

  In addition,% Cp,% CN, and% CA as used in the present invention are percentages of the total number of paraffin carbons determined by a method (ndM ring analysis) based on ASTM D 3238-85, It means the percentage of the total number of naphthene carbons and the percentage of the total number of aromatic carbons. That is, the preferable ranges of% Cp,% CN and% CA described above are based on the values obtained by the above method. For example, even if the lubricating base oil does not contain naphthene, the% CN obtained by the above method is used. May show a value greater than zero.

  Further, the content of the saturated component in the lubricating base oil according to the present invention is not particularly limited as long as the kinematic viscosity at 100 ° C. satisfies the above conditions, but preferably 90% by mass based on the total amount of the lubricating base oil. Or more, preferably 95% by mass or more, more preferably 99% by mass or more, and the ratio of the cyclic saturated component in the saturated component is preferably 40% by mass or less, preferably 35% by mass or less. Preferably, it is 30 mass% or less, More preferably, it is 25 mass% or less, More preferably, it is 21 mass% or less. When the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, the viscosity-temperature characteristics and the thermal / oxidative stability can be improved. When the additive is blended, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricating base oil. Furthermore, according to the present invention, it is possible to improve the friction characteristics of the lubricating base oil itself, and as a result, it is possible to achieve an improvement in the friction reduction effect and an improvement in energy saving.

  The saturated content in the present invention is measured by the method described in the ASTM D 2007-93.

  The aromatic content in the lubricating base oil according to the present invention is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and preferably 0.1% by mass. Above, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, particularly preferably 1.5% by mass or more. If the aromatic content exceeds the upper limit, the heat / oxidation stability and friction characteristics, as well as volatilization prevention properties and low-temperature viscosity characteristics tend to decrease.

  In addition, the aromatic component as used in the field of this invention means the value measured based on ASTM D 2007-93. In general, the aromatic component includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, as well as compounds in which four or more benzene rings are condensed, pyridines, quinolines, phenols and naphthols. Aromatic compounds having atoms are included.

  The urea adduct value of the lubricating base oil according to the present invention is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2.5% by mass or less, and particularly preferably 2% by mass. It is as follows. Further, from the viewpoint of sufficient low-temperature viscosity characteristics, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 0.8% by mass or more.

  Here, the “urea adduct value” in the present invention means a value measured by the following method. 100 g of weighed sample oil (lubricating base oil) is placed in a round bottom flask, 200 mg of urea, 360 ml of toluene and 40 ml of methanol are added and stirred at room temperature for 6 hours. As a result, white granular crystals are produced as urea adducts in the reaction solution. The reaction solution is filtered through a 1 micron filter to collect the produced white granular crystals, and the obtained crystals are washed 6 times with 50 ml of toluene. The recovered white crystals are put in a flask, 300 ml of pure water and 300 ml of toluene are added, and the mixture is stirred at 80 ° C. for 1 hour. The aqueous phase is separated and removed with a separatory funnel, and the toluene phase is washed three times with 300 ml of pure water. A desiccant (sodium sulfate) is added to the toluene phase for dehydration, and then toluene is distilled off. The ratio (mass percentage) of the urea adduct thus obtained to the sample oil is defined as the urea adduct value.

  In the lubricating oil composition of the present invention, the lubricating base oil according to the present invention may be used alone, and the lubricating base oil according to the present invention may be one or more of other base oils. You may use together. When the lubricating base oil according to the present invention is used in combination with another base oil, the ratio of the lubricating base oil according to the present invention in the mixed base oil is preferably 30% by mass or more. 50% by mass or more is more preferable, and 70% by mass or more is still more preferable.

As another base oil used in combination with the lubricating base oil according to the present invention, the mineral oil base oil has, for example, a kinematic viscosity at 100 ° C. of 1 to 100 mm ² / s, solvent refined mineral oil, hydrocracked mineral oil Hydrorefined mineral oil, solvent dewaxing base oil and the like.

  Synthetic base oils include polyα-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (ditridecylglutarate) whose kinematic viscosity at 100 ° C. does not satisfy the above conditions. Rate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyol esters (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, Pentaerythritol pelargonate), polyoxyalkylene glycol, dialkyldiphenyl ether, polyphenyl ether, etc. Is preferred. As the poly α-olefin, typically, an α-olefin oligomer or co-oligomer having 1 to 32 carbon atoms, preferably 6 to 16 (1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, etc.) and the like. Of the hydrides.

  The production method of the poly-α-olefin is not particularly limited. For example, Friedel Crafts containing a complex of aluminum trichloride or boron trifluoride with water, alcohol (ethanol, propanol, butanol, etc.), carboxylic acid or ester. The method of superposing | polymerizing an alpha olefin in presence of a polymerization catalyst like a catalyst is mentioned.

  The viscosity index of the lubricating oil composition of the present invention is preferably in the range of 200 to 350, more preferably 210 to 300, still more preferably 220 to 300, particularly preferably 240 to 300, and most preferably 260. ~ 300. When the viscosity index of the lubricating oil composition of the present invention is less than 200, it may be difficult to improve fuel economy while maintaining the HTHS viscosity, and the low temperature viscosity at −35 ° C. is further reduced. May be difficult. In addition, when the viscosity index of the lubricating oil composition of the present invention is 350 or more, low temperature fluidity is deteriorated, and there is a risk that problems due to insufficient solubility of the additive and compatibility with the sealing material may occur. There is.

  In addition to the kinematic viscosity and viscosity index at 100 ° C. satisfying the above requirements, the lubricating oil composition of the present invention preferably satisfies the following requirements.

The kinematic viscosity at 40 ° C. of the lubricating oil composition of the present invention is preferably 4 to 50 mm ² / s, preferably 45 mm ² / s or less, more preferably 40 mm ² / s or less, and still more preferably 35 mm ² / s. s or less, particularly preferably 30 mm ² / s or less, and most preferably 27 mm ² / s or less. On the other hand, the 40 ° C. kinematic viscosity is preferably 5 mm ² / s or more, more preferably 10 mm ² / s or more, further preferably 15 mm ² / s or more, and particularly preferably 20 mm ² / s or more. If the kinematic viscosity at 40 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 50 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

  The HTHS viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 6.0 mPa · s or less, more preferably 5.5 mPa · s or less, and even more preferably 5.3 mPa · s or less. Particularly preferably, it is 5.0 mPa · s or less, and most preferably 4.5 mPa · s or less. Further, it is preferably 3.0 mPa · s or more, preferably 3.5 mPa · s or more, more preferably 3.8 mPa · s or more, particularly preferably 4.0 mPa · s or more, and most preferably 4.2 mPa · s or more. s or more. The HTHS viscosity at 100 ° C. here refers to the high temperature and high shear viscosity at 100 ° C. defined in ASTM D4683. When the HTHS viscosity at 100 ° C. is less than 3.0 mPa · s, there is a risk of high evaporability and insufficient lubricity. When it exceeds 6.0 mPa · s, the necessary low temperature viscosity and sufficient fuel saving Performance may not be obtained.

  The lubricating oil composition of the present invention has an HTHS viscosity at 150 ° C. of preferably 3.5 mPa · s or less, more preferably 3.0 mPa · s or less, and even more preferably 2.8 mPa · s or less. Particularly preferably, it is 2.7 mPa · s or less. Further, it is preferably 2.0 mPa · s or more, preferably 2.3 mPa · s or more, more preferably 2.4 mPa · s or more, particularly preferably 2.5 mPa · s or more, and most preferably 2.6 mPa · s. s or more. The HTHS viscosity at 150 ° C. here refers to the high temperature and high shear viscosity at 150 ° C. defined in ASTM D4683. When the HTHS viscosity at 150 ° C. is less than 2.0 mPa · s, there is a risk of high vaporization and insufficient lubricity. When it exceeds 3.5 mPa · s, the necessary low-temperature viscosity and sufficient fuel saving Performance may not be obtained.

In the lubricating oil composition of the present invention, it is preferable that the ratio of the HTHS viscosity at 100 ° C. to the HTHS viscosity at 150 ° C. satisfies the condition represented by the following formula (A).
HTHS (100 ° C.) / HTHS (150 ° C.) ≦ 2.04 (A)
[Wherein, HTHS (100 ° C.) represents the HTHS viscosity at 100 ° C., and HTHS (150 ° C.) represents the HTHS viscosity at 150 ° C. ]

  HTHS (100 ° C.) / HTHS (150 ° C.) is preferably 2.04 or less, more preferably 2.00 or less, still more preferably 1.98 or less, still more preferably 1.80 or less, and particularly preferably 1.70 or less. If HTHS (100 ° C.) / HTHS (150 ° C.) exceeds 2.04, sufficient fuel saving performance and low temperature characteristics may not be obtained. Further, HTHS (100 ° C.) / HTHS (150 ° C.) is preferably 0.50 or more, more preferably 0.70 or more, still more preferably 1.00 or more, and particularly preferably 1.30 or more. When HTHS (100 ° C.) / HTHS (150 ° C.) is less than 0.50, there is a possibility that the cost of the substrate is significantly increased and the solubility of the additive cannot be obtained.

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

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

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

<Production Example 1>
In a reaction vessel equipped with a temperature control device, a vacuum stirring blade, a nitrogen inlet and an outlet, a terminal unsaturated group-containing polybutene (trade name: “NOF Polybutene 10N”, manufactured by NOF Corporation, Mn: 1,000 280 parts by weight, 400 parts by weight of tetrahydrofuran-boron-tetrahydrofuran 1 mol / L solution [manufactured by Wako Pure Chemical Industries, Ltd.] and 400 parts by weight of tetrahydrofuran were added, and hydroboration was performed for 4 hours at 25 ° C. Next, water 50 Part by weight, 50 parts by volume of a 3N-NaOH aqueous solution and 50 parts by weight of 30% by weight hydrogen peroxide were added to oxidize, and the supernatant was recovered with a separatory funnel, heated to 50 ° C., and then depressurized at the same temperature. Lower (0.027-0.040 MPa) tetrahydrofuran was removed over 2 hours to obtain a hydroxyl group-containing polymer (Y2-1) having one terminal.

<Production Example 2>
In a pressure-resistant reaction vessel made of SUS equipped with a temperature control device and a stirrer, polyunsene containing terminal unsaturated groups (trade name; “NOF Polybutene 200N”, manufactured by NOF Corporation, Mn: 2,650], 530 parts by weight, and 25 parts by weight of maleic anhydride [manufactured by Wako Pure Chemical Industries, Ltd.] was added, the temperature was raised to 220 ° C. with stirring, and an ene reaction was carried out for 4 hours at the same temperature. 20 parts by weight was added, the temperature was raised to 130 ° C. with stirring, and an imidization reaction was carried out for 4 hours at the same temperature, and an unreacted anhydrous maleate under reduced pressure (0.027 to 0.040 MPa) at 120 to 130 ° C. The acid and 2-aminoalcohol were removed over 2 hours to obtain a one-terminal hydroxyl group-containing polymer (Y3-1).

<Examples 1-5, Comparative Examples 1-6>
In a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen introduction tube, API group III base oil A [SP value: 8.10 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C .: 4.2 mm ² / s, viscosity index: 128] 400 parts by weight, 100 parts by weight of the monomer composition described in Table 1, 0.2 part by weight of 2,2′-azobis (2-methylbutyronitrile) Then, after nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76 ° C. with stirring in a sealed state, and a polymerization reaction was carried out at the same temperature for 4 hours. After raising the temperature to 120 to 130 ° C., unreacted monomers are removed under reduced pressure (0.027 to 0.040 MPa) at the same temperature over 2 hours, and the copolymers (A1) to (A5), (H1 ) To (H6), viscosity index improvers (R1) to (R5) and (S1) to (S6) were obtained. SP values of the obtained copolymers (A1) to (A5) and (H1) to (H6) were calculated by the above method, and Mw was measured by the above method. Moreover, the base oil solubility of the copolymer was evaluated by the following method. The results are shown in Table 1.

<Evaluation method of base oil solubility of copolymer>
The appearance of the viscosity index improvers (R1) to (R5) and (S1) to (S6) was visually observed, and the base oil solubility was evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: Appearance is uniform and there is no insoluble matter in the copolymer ×: Appearance is inhomogeneous and insoluble matter in the copolymer is observed

The compositions of the monomers (a) to (h) described in Table 1 are as described below.
(Y1-1): One-terminal hydroxyl group-containing polymer of hydrogenated polybutadiene (trade name: Krasol HLBH-5000M, manufactured by Cray Valley, 1,2-butylene ratio: 65 mol%, hydroxyl value: 10.4 mg KOH / g, Mn 5400)
(Y2-1): Hydroboration product of polybutene containing unsaturated group at one end in Production Example 1 (Y3-1): Maleic anhydride-ene-aminoalcohol adduct of polybutene containing unsaturated group at one end of Production Example 2 a1-1): (Y1-1) Methacrylate ester (a1-2): (Y2-1) Methacrylate ester (a1-3): (Y3-1) Methacrylate ester
(B-1): 2-n-decyltetradecyl methacrylate (b-2): 2-n-dodecyl hexadecyl methacrylate (c-1): methyl tridecyl methacrylate (2-methyl tridecyl methacrylate 30) % By weight, a mixture of 70% by weight of 5-methyltridecyl methacrylate)
(C-2): methyl heptadecyl methacrylate (mixture of 50% by weight of 5-methylheptadecyl methacrylate and 50% by weight of 13-methylheptadecyl methacrylate)
(D-1): methyl methacrylate (d-2): butyl methacrylate (d-3): ethoxyethyl methacrylate (d-4): butoxyethyl methacrylate (e-1): n-dodecyl methacrylate ( e-2): n-tetradecyl methacrylate (e-3): n-hexadecyl methacrylate (f-1): N, N-dimethylaminoethyl methacrylate (g-1): hydroxyethyl methacrylate (h-1): Methacryloyloxyethyl phosphate

<Examples 6 to 10 and Comparative Examples 7 to 12>
In a stainless steel container equipped with a stirrer, API group III base oil A [SP value: 8.10 (cal / cm ³ ) ^1/2 , kinematic viscosity at 100 ° C .: 4.2 mm ² / s, viscosity index: 128], and viscosity index improvers (R1) to (R5), respectively, so that the HTHS viscosity at 150 ° C. of the resulting lubricating oil composition is 2.60 ± 0.05 (mm ² / s), (S1) to (S6) were added to obtain lubricating oil compositions (V1) to (V5) and (W1) to (W6).
The shear stability, HTHS viscosity (100 ° C.), and viscosity index of the lubricating oil compositions (V1) to (V5) and (W1) to (W6) were measured by the following methods. The results are shown in Table 2.

<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>
The measurement was performed at 100 ° C. by the method of ASTM D 5481.

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

  As is clear from the results in Table 2, the lubricating oil compositions (Examples 4 to 6) containing the viscosity index improver of the present invention are excellent in shear stability and have a low HTHS viscosity in the effective temperature range. It can be seen that the viscosity index is high and excellent. On the other hand, it can be seen that the lubricating oil compositions of Comparative Examples 7 to 12 are inferior in at least one of shear stability, HTHS viscosity in the effective temperature range, and viscosity index.

The lubricating oil composition containing the viscosity index improver of the present invention includes a drive system lubricating oil (MTF, differential gear oil, ATF, belt-CVTF, etc.), 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)

In a viscosity index improver composition comprising a (co) polymer (A) having a (meth) acrylate monomer having a branched alkyl group having 10 or more carbon atoms as a constituent monomer and a base oil, the following formula (1) The degree of branching (CB) of the branched alkyl group of the (meth) acrylate monomer derived from (1) is derived from the absolute value (ΔSP) of the difference between the solubility parameter of (A) and the solubility parameter of the base oil. A viscosity index improver composition comprising a (co) polymer (A) satisfying the formulas (2) and (3).
(CB) = Σ [(BC) / (AC) × (BWT)] / (LCWT) (1)
0.83 × (ΔSP) −0.75 <(CB) (2)
0.25 ≦ (CB) ≦ 0.5 (3)
BC: In each constituent monomer of the (meth) acrylate monomer, the number of carbon atoms in the branched alkyl group side chain AC: In each constituent monomer of the (meth) acrylate monomer, a branched alkyl group is added. Number of total carbon atoms constituting BWT: Weight ratio of each constituent monomer of (meth) acrylate monomer to weight of (A) (%)
LCWT: Weight ratio (%) of the total constituent monomers of the (meth) acrylate monomer to the weight of (A)   The viscosity index improver composition according to claim 1, wherein ΔSP of (A) and the base oil is 1.1 to 1.5. The viscosity index improver composition according to claim 1 or 2, wherein (A) is essential to be dissolved in a base oil of API group III having a kinematic viscosity of 4 to 6 mm ² / s at 100 ° C. The (meth) acrylate monomer is represented by the monomer (a) represented by the general formula (1), the monomer (b) represented by the general formula (2), and the general formula (3). The viscosity index improver composition according to any one of claims 1 to 3, which is at least one monomer selected from the group of monomers (c).
[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 Residue obtained by removing one hydrogen atom from a hydrocarbon polymer having a number average molecular weight of 1,000 or more having isobutylene and / or 1,2-butylene as an essential constituent unit; p is a number of 0 or 1]
[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 is independently A linear alkyl group having 4 to 24 carbon atoms; q is an integer of 0 to 20, and when q is 2 or more, R ⁴ may be the same or different, and the (R ⁴ O) _q moiety may be a random bond Block combination may be used. ]
[R ⁶ is a hydrogen atom or a methyl group; —X ³ — is a group represented by —O— or —NH—; R ⁷ is a hydrogen atom or a methyl group; — [CH (R ⁷ )] _n —CH ₃ Carbon number of the group represented is 14 to 40; n is an integer of ^{7 to} 38, n pieces of R ⁷ are each independently a hydrogen atom or a methyl group, and at least one of n pieces of R ⁷ Is a methyl group. ] (A) is a copolymer containing the monomer (d) represented by the general formula (4) as a constituent monomer of (A), and The viscosity index improvement according to any one of claims 1 to 4, wherein the sum of the proportions of monomers (a), (b), (c) and (d) is 5 to 95% by weight based on the weight of Agent composition.
[R ⁸ is a hydrogen atom or a methyl group; —X ⁴ — is a group represented by —O— or —NH—; R ⁹ is an alkylene group having 2 to 4 carbon atoms; R ¹⁰ is an alkyl having 1 to 6 carbon atoms; Group; r is an integer of 0 to 10, and R ⁹ when r is 2 or more may be the same or different, and the (R ⁹ O) _r moiety may be a random bond or a block bond. ]   (A) is a copolymer comprising (meth) acrylic acid alkyl ester (e) having a linear alkyl group having 12 to 36 carbon atoms as a constituent monomer of (A). -Viscosity index improver composition in any one of -5.   The viscosity index improver composition according to claim 6, wherein (A) is a copolymer containing 1 to 40% by weight of (e) based on the weight of (A) as a constituent monomer.   (A) is further selected from the group consisting of a nitrogen atom-containing monomer (except (a) to (d)) (f), a hydroxyl group-containing monomer (g), and a phosphorus atom-containing monomer (h). The viscosity index improver composition according to claim 6 or 7, which is a copolymer having at least one selected monomer as a constituent monomer.   The viscosity index improver composition according to any one of claims 1 to 8, wherein the weight average molecular weight of (A) is 100,000 to 1,000,000.   Furthermore, the (co) polymer (B) other than (A) is contained in an amount of 0.01 to 30% by weight based on the weight of (A). Agent composition.   Furthermore, it contains at least one additive selected from the group consisting of detergents, dispersants, antioxidants, oiliness improvers, friction wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers and corrosion inhibitors. The lubricating oil composition according to any one of claims 1 to 10. The lubricating oil composition according to claim 11, wherein the base oil has a kinematic viscosity at 100 ° C. of 1 to 10 mm ² / s and the base oil has a viscosity index of 120 or more.