JP2022184773A - Lubricant composition - Google Patents

Abstract

To provide a lubricant composition that makes it possible to reduce a viscosity at low temperatures (at 60-100°C) while keeping a relatively high viscosity at high temperatures even when the NOACK evaporation is kept in a low range, and also to reduce a rolling frictional coefficient (MTM frictional coefficient).SOLUTION: A lubricant composition contains a (co)polymer (A) that includes a main chain having a polymerizable monomer-derived repeat unit and a side chain having a polyolefin structure, an ester oil (B), a sanitizer and/or a dispersant and an antioxidant. The lubricant composition has an HTHS viscosity of 2.55-2.80 mPa s at 150°C. The lubricant composition has an HTHS viscosity of 3.0-5.0 mPa s at 100°C. The lubricant composition has an HTHS viscosity of 4.0-6.5 mPa s at 80°C. The lubricant composition has an HTHS viscosity of 8.0-11.0 mPa s at 60°C. The lubricant composition has a NOACK evaporation of 15-25 wt.%.SELECTED DRAWING: Figure 1

Description

The present invention relates to lubricating oil compositions.

In recent years, in order to reduce CO ₂ emissions and conserve petroleum resources, there has been an increasing demand for fuel-saving automobiles. 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. For this problem, the US SAE engine oil viscosity standard (SAE J300) stipulates the minimum guaranteed viscosity, and in the 0W-20 grade, the viscosity under high temperature and high shear (HTHS viscosity) is 150 °C HTHS viscosity (ASTM D4683 or D5481) is specified as 2.6 mPa·s or more and 0W-16 grade as 2.3 mPa·s or more.

Regarding fuel efficiency, there is a demand for engine oils that meet the above standards and have lower viscosity (HTHS viscosity) under high temperature and high shear conditions at 100°C, 80°C and 60°C. A method of using a large amount of low-viscosity base oil is also known. However, there is a problem that the evaporation loss rate of the engine oil (NOACK evaporation amount [engine oil evaporation test method, ASTM D5800]) is worsened. On the other hand, in order to reduce _CO2 emissions and conserve petroleum resources, hybrid vehicles and electric vehicles are rapidly becoming popular. In particular, with the spread of hybrid vehicles, the frequency of engine operation has decreased and the frequency of low oil temperature operation has increased. Therefore, while the HTHS viscosity on the low temperature side is important for improving fuel efficiency, the reliability on the high temperature side is also required from the viewpoint of reliability during high-speed operation, although the frequency is low. Therefore, it is necessary to ensure a relatively high HTHS viscosity that is appropriate even on the high temperature side (Patent Documents 1 to 4).
On the other hand, conventional lubricating oil compositions have the problem that their viscosities increase at low temperatures and exhibit high coefficients of friction even in rolling friction tests. It has been difficult to reduce HTHS viscosity at low temperatures, exhibit low friction in rolling friction tests, and maintain relatively high HTHS viscosities at high temperatures while keeping NOACK evaporation low.

JP 2013-147608 A WO2015/129732 JP 2017-57378 A JP 2020-105347 A

The object of the present invention is to reduce fuel consumption, and even when the NOACK evaporation amount is suppressed to a low range, while maintaining a relatively high HTHS viscosity at high temperature (150 ° C), at low temperature (60 to 100 ° C). It is an object of the present invention to provide a lubricating oil composition capable of reducing the HTHS viscosity of , and reducing the rolling friction coefficient (MTM friction coefficient).

The present inventors arrived at the present invention as a result of earnest studies.
That is, the present invention
a (co)polymer (A) having a main chain having a repeating unit derived from a polymerizable monomer and a side chain having a polyolefin structure;
an ester oil (B);
A lubricating oil composition containing a detergent and/or dispersant and an antioxidant,
The HTHS viscosity of the lubricating oil composition at 150° C. is 2.55 to 2.80 mPa s, and the HTHS viscosity of the lubricating oil composition at 100° C. is 3.0 to 5.0 mPa s. The lubricating oil composition has an HTHS viscosity of 4.0 to 6.8 mPa s at 80 ° C., and a lubricating oil composition having an HTHS viscosity of 8.0 to 11.0 mPa s at 60 ° C. The NOACK evaporation of the composition is 15-25% by weight.

The lubricating oil composition of the present invention maintains a relatively high HTHS viscosity at high temperatures (150° C.) and maintains a relatively high HTHS viscosity at low temperatures (60 to 100° C.) even when NOACK evaporation is suppressed to a low range. , the rolling friction coefficient (MTM friction coefficient) can be reduced, and the fuel consumption can be reduced.

1 is a graph showing the relationship between the HTHS viscosity at 60° C. (horizontal axis) and the MTM friction coefficient at 40° C. (vertical axis) of the lubricating oil compositions obtained in Examples and comparative examples. . 1 is a graph showing the relationship between the HTHS viscosity at 100° C. (horizontal axis) and the MTM friction coefficient at 100° C. (vertical axis) of lubricating oil compositions obtained in Examples and comparative examples. .

The lubricating oil composition of the present invention comprises a (co)polymer (A) having a main chain having a repeating unit derived from a polymerizable monomer and a side chain having a polyolefin structure,
an ester oil (B);
A lubricating oil composition containing a detergent and/or dispersant and an antioxidant,
The HTHS viscosity of the lubricating oil composition at 150° C. is 2.55 to 2.80 mPa s, and the HTHS viscosity of the lubricating oil composition at 100° C. is 3.0 to 5.0 mPa s. The lubricating oil composition has an HTHS viscosity of 4.0 to 6.8 mPa s at 80 ° C., and a lubricating oil composition having an HTHS viscosity of 8.0 to 11.0 mPa s at 60 ° C. The NOACK evaporation of the composition is 15-25% by weight.

<(Co)polymer (A)>
In the present invention, the (co)polymer (A) has a main chain having a repeating unit derived from a polymerizable monomer and a side chain having a polyolefin structure.
Polymerizable monomers include those having a radically polymerizable carbon-carbon double bond {vinyl group (H ₂ C=CH-), vinylidene group or vinylene group (-HC=CH-)}, for example, ( meth)acryloyl group, carbon-carbon double bond {-OC(O)HC=CH-C(O)O-} in mono- or diester of (anhydride) maleic acid or fumaric acid, vinyl ether group, styryl group, etc. monomers having Among these, monomers having a (meth)acryloyl group are preferred. When the polymerizable monomer has a (meth)acryloyl group, the (co)polymer has a highly polar group (ester group, amide group, etc.) near the main chain skeleton and a non-polar polyolefin structure as a side chain. At a high temperature (150 ° C. ), the long side chains of the (co)polymer (A) spread and can be as high as 2.55 to 2.80 mPa s. The polymer chains of the polymer (A) tend to be small and grouped around the main chain, and the increase in the viscosity of the base oil due to a decrease in temperature can be suppressed. 0 to 6.8 mPa s and 8.0 to 11.0 mPa s at 60°C. It is speculated that the MTM coefficient of friction can be reduced.

［一般式（１）においてＲ^１は水素原子又はメチル基；－Ｘ^１－は－Ｏ－、－Ｏ（ＡＯ）_ｍ－又は－ＮＨ－で表される基であって、Ａは炭素数２～４のアルキレン基であり、ｍは１～１０の整数であり、ｍが２以上の場合のＡは同一でも異なっていてもよい；Ｒ^２は１，２－ブチレン基を構成単位として含む炭化水素重合体から水素原子を１つ除いた残基；ｐは０又は１の数である。］ In the present invention, the (co)polymer (A) is a constituent monomer having a polyolefin structure having 50 to 1,000 carbon atoms at one end and a (meth)acryloyl group at the other end. is preferably a (co)polymer containing as, more preferably containing a monomer (a) represented by the following general formula (1) as a constituent monomer.
When the monomer (a) represented by the following general formula (1) is used as a constituent monomer, R ² of the monomer (a) is the "side having a polyolefin structure" in the (co)polymer (A) chain. One type of the monomer (a) may be used, or two or more types may be used in combination.

[In general formula (1), 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 has 2 carbon atoms; is an alkylene group of ∼4, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R ² is a carbonization containing a 1,2-butylene group as a structural unit A residue obtained by removing one hydrogen atom from a hydrogen polymer; p is a number of 0 or 1; ]

R ¹ in the general formula (1) is a hydrogen atom or a methyl group, which increases the molecular behavior of (A) with respect to temperature (low temperature (60 to 100°C) HTHS when the viscosity of 150°C HTHS is adjusted to be constant) A methyl group is preferable from the viewpoint of lowering the viscosity (same below).

-X ¹ - in general formula (1) is a group represented by -O-, -O(AO) _m - or -NH-.
A is an alkylene group having 2 to 4 carbon atoms.
Examples of the alkylene group having 2 to 4 carbon atoms include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3- or 1,4-butylene group.
m is an integer of 1 to 10, preferably an integer of 1 to 4, more preferably an integer of 1 to 2 from the viewpoint of solubility in the base oil (ester oil (B), etc., the same applies hereinafter). be.
When m is 2 or more, A may be the same or different, and the (AO) _m portion may be a random bond or a block bond.
-X ¹ - is preferably a group represented by -O- or -O(AO) _m -, more preferably -O- or -O( It is a group represented by CH ₂ CH ₂ O) _m —.

p in the general formula (1) is a number of 0 or 1, preferably 0 from the viewpoint of solubility in the base oil.

R ² in general formula (1) is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit. The number of carbon atoms in the hydrocarbon polymer is preferably 50 to 1,000 from the viewpoint of increasing the molecular behavior of (A) with respect to temperature.
The 1,2-butylene group is a group represented by -CH ₂ CH(CH ₂ CH ₃ )- or -CH(CH ₂ CH ₃ )CH ₂ -.
Hydrocarbon polymers having 1,2-butylene groups as constituent units include polymers using 1-butene as constituent monomers (unsaturated hydrocarbon (x)), and 1 obtained by polymerizing 1,3-butadiene. , a polymer obtained by hydrogenating the double bond of a 2-adduct.
In addition to 1-butene and 1,3-butadiene, the hydrocarbon polymer may contain one or more of the following (1) to (3) as unsaturated hydrocarbons (x) as constituent monomers.
(1) aliphatic unsaturated hydrocarbons [olefins having 2 to 36 carbon atoms (e.g., ethylene, propylene, isobutene, 2-butene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, triacosene, hexatriacosene, etc.) and dienes having 4 to 36 carbon atoms (e.g., isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.), etc.]
(2) alicyclic unsaturated hydrocarbons [e.g. cyclohexene, (di)cyclopentadiene, pinene, limonene, indene, vinylcyclohexene and ethylidenebicycloheptene, etc.]
(3) aromatic group-containing unsaturated hydrocarbons (e.g. styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotyl benzene, vinylnaphthalene, divinylbenzene, divinyltoluene, divinylxylene and trivinylbenzene, etc.)
The hydrocarbon polymer composed of these may be a block polymer or a random polymer. Further, when the hydrocarbon polymer has double bonds, it may be obtained by hydrogenating part or all of the double bonds by hydrogenation. In one embodiment, the hydrocarbon polymer for R ² may be a hydrocarbon polymer using only a monomer having 4 carbon atoms as a constituent monomer, and the monomer having 4 carbon atoms is 1-butene and 1,3-butadiene.

The number average molecular weight (hereinafter abbreviated as Mn) of the monomer (a) is preferably 800 to 10,000, more preferably 1,000 to 9,000, still more preferably 1,200 to 8, 500, particularly preferably 2,000 to 8,000. When the Mn of the monomer (a) is 800 or more, the solubility in the base oil tends to be good, and when it is 10,000 or less, the copolymerizability with other monomers tends to be good. There is

In the present invention, the weight average molecular weight (hereinafter abbreviated as Mw) and Mn can be measured by gel permeation chromatography (hereinafter abbreviated as GPC) under the following conditions.
<Mw and Mn measurement conditions>
Apparatus: "HLC-8320GPC" [manufactured by Tosoh Corporation]
Column: 2 "TSKgel GMHXL" [manufactured by Tosoh Corporation]
"TSKgel Multipore H _XL -M 1 measurement temperature: 40 ° C
Sample solution: 0.25% by weight tetrahydrofuran solution Injection amount: 10.0 µl
Detection device: Refractive index detector Standard substance: Standard polystyrene (TS Standard substance: Standard polystyrene (TSKstandard POLYSTYRENE)
12 points (molecular weight: 589, 1,050, 2,630, 9,100, 19,500, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,110,000 , 4,480,000) [manufactured by Tosoh Corporation]

The monomer (a) is an esterification reaction between a polymer (Y) containing a hydroxyl group at one end obtained by introducing a hydroxyl group at one end of a hydrocarbon polymer and (meth)acrylic acid, or It can be obtained by transesterification with an alkyl (meth)acrylate (preferably having 1 to 4 carbon atoms) such as methyl (meth)acrylate. In addition, "(meth)acryl" means "acryl and/or methacryl".

Specific examples of the polymer (Y) containing a hydroxyl group at one end include the following (Y1) to (Y4).
Alkylene oxide adduct (Y1): A hydrocarbon polymer obtained by polymerizing an unsaturated hydrocarbon (x) in the presence of an ionic polymerization catalyst (such as a sodium catalyst) is added with an alkylene oxide (such as ethylene oxide and propylene oxide). Those obtained by addition (in this case, the monomer (a) is a compound in which -X ¹ - is -(AO) _m - and p=0 in general formula (1)).
Hydroboride (Y2); a hydroboration reaction product of a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end (for example, those described in U.S. Pat. No. 4,316,973) ) and the like (in this case, the monomer (a) is a compound in which -X ¹ - is -O- and p=0 in the general formula (1)).
Maleic anhydride-ene-aminoalcohol adduct (Y3); a reactant obtained by an ene reaction between a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end and maleic anhydride, Those obtained by imidization with an amino alcohol (in this case, the monomer (a) is a compound in which -X ¹ - is -O- and p is 1 in general formula (1)).
Hydroformyl hydride (Y4); obtained by hydroformylating a hydrocarbon polymer of unsaturated hydrocarbon (x) having a double bond at one end and then hydrogenating it (for example, JP-A-63-175096 (In this case, the monomer (a) is a compound in which —X ¹ — is —O— and p=0 in general formula (1)).
Among these polymers (Y) containing a hydroxyl group at one end, alkylene oxide adducts (Y1) and hydroborides (Y2) are preferred from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. , and more preferred is the alkylene oxide adduct (Y1).

Ratio of 1,3-butadiene (hereinafter sometimes abbreviated as butadiene) to all monomers constituting R ² in general formula (1) (carbonization containing 1,2-butylene group as a structural unit In the hydrogen polymer, the weight ratio of 1,3-butadiene in all constituent monomers) is preferably 50% by weight or more, more preferably 75% by weight, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. Above, more preferably 85% by weight or more, particularly preferably 90% by weight or more.

The hydrocarbon polymer containing 1,2-butylene groups in general formula (1) as structural units may have an isobutylene group from the viewpoint of enhancing the molecular behavior of (A) with respect to temperature.
The total amount of isobutylene groups and 1,2-butylene groups is 30 mol% or more based on the total number of moles of structural units of the hydrocarbon polymer, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. preferably 40 mol % or more, and still more preferably 50 mol % or more.
As a method for increasing the ratio of the total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer, for example, the following method can be employed. In the case of the above alkylene oxide adduct (Y1), for example, in the anionic polymerization using 1,3-butadiene, the reaction temperature is lowered {for example, the boiling point of 1,3-butadiene (−4.4° C.) or lower}, In addition, by reducing the amount of the polymerization initiator charged relative to 1,3-butadiene, the ratio of the total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer can be increased. In the case of the above hydroboride (Y2), maleic anhydride-ene-aminoalcohol adduct (Y3) and hydroformyl-hydride (Y4), the degree of polymerization of the hydrocarbon polymer having a double bond at one end is increased. By doing so, the above ratio can be increased.

The total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer containing 1,2-butylene groups as structural units in general formula (1) can be measured by ¹³ C-NMR. Specifically, for example, when only a monomer having 4 carbon atoms is used, the hydrocarbon polymer is analyzed by ¹³ C-NMR and calculated using the following formula (1). It is possible to determine the total mole % of the isobutylene group and the 1,2-butylene group based on the total number of moles of the constitutional units. In ¹³ C-NMR, the peak derived from the methyl group of the isobutylene group is the integrated value (integral value A) of 30 to 32 ppm, the branched methylene group (-CH ₂ CH (CH ₂ CH ₃ )- of the 1,2-butylene group) Alternatively, a peak derived from —CH(CH ₂ CH ₃ )CH ₂ —) appears at an integral value (integral value B) of 26 to 27 ppm. The total mol % of the isobutylene group and the 1,2-butylene group based on the total number of moles of the structural units of the hydrocarbon polymer is the integrated value of the above peak and the integrated value of the total carbon peak of the hydrocarbon polymer ( It can be obtained from the integrated value C).
Total amount of isobutylene group and 1,2-butylene group (mol%) = 100 x {(integral value A) x 2 + (integral value B) x 4}/(integral value C) (1)

When the hydrocarbon polymer in R ² contains butadiene, or ^butadiene and 1-butene as constituent monomers, butadiene or butadiene and 1 -In the structure derived from butene, the molar ratio of 1,2-adduct and 1,4-adduct (1,2-adduct/1,4-adduct) increases the molecular behavior of (A) with respect to temperature And from the viewpoint of copolymerizability with other monomers, it is preferably 5/95 to 95/5, more preferably 20/80 to 80/20, and still more preferably 30/70 to 70/30.

When the hydrocarbon polymer for R ² contains butadiene, or ^butadiene and 1-butene as constituent monomers, butadiene or butadiene and 1 The molar ratio of 1,2-adduct/1,4-adduct in the structure derived from -butene can be measured by ¹ H-NMR, ¹³ C-NMR, Raman spectroscopy, or the like.

単量体（ａ）に由来する構成単位のＳＰ値は、単量体（ａ）に由来する構成単位の分子構造に基づいて、前記パラメータを用いて算出することができ、使用する単量体（不飽和炭化水素（ｘ））、単量体（不飽和炭化水素（ｘ））の重量分率を適宜調整することにより所望の範囲にすることができる。
また、（共）重合体（Ａ）が２種以上の単量体（ａ）を併用している場合は、（ａ）を構成する複数の単量体（炭素－炭素二重結合が単結合になった構成単位）それぞれのＳＰ値を前記の方法で算出し、それぞれの単量体（ａ）のＳＰ値を、構成単量体単位の重量分率に基づいて相加平均値した値が前記単量体（ａ）のＳＰ値の範囲を満たすことが好ましい。 The solubility parameter (hereinafter abbreviated as SP value) of the structural unit derived from the monomer (a) (the structure in which the carbon-carbon double bond of (a) reacts to form a single bond) is (A ) is preferably 7.0 to 9.0 (cal/cm ³ ) ^1/2 , more preferably 7.3 to 8.5, from the viewpoint of moderate SP value and solubility in base oil. (cal/cm ³ ) ^1/2 .
For example, the SP value tends to be smaller when the degree of branching of R ² is high and the number of carbon atoms is large, and tends to be large when the degree of branching is low and the number of carbon atoms is small.
The SP value in the present invention is the numerical value (atom or functional group (heat of vaporization at 25°C and molar volume of
Specifically, from the numerical values of Δe _i and v _i described in Table 1 below, which are parameters of the Fedors method, numerical values corresponding to the types of atoms and atomic groups in the molecular structure are used and applied to the following formula. can be calculated.
SP value = (ΣΔe _i /Σv _i ) ^1/2

The SP value of the structural unit derived from the monomer (a) can be calculated using the parameters based on the molecular structure of the structural unit derived from the monomer (a). A desired range can be obtained by appropriately adjusting the weight fractions of (unsaturated hydrocarbon (x)) and monomer (unsaturated hydrocarbon (x)).
Further, when the (co)polymer (A) uses two or more types of monomers (a) in combination, a plurality of monomers constituting (a) (carbon-carbon double bond is a single bond The SP value of each structural unit) was calculated by the above method, and the SP value of each monomer (a) was arithmetically averaged based on the weight fraction of the constituent monomer units. It is preferable to satisfy the SP value range of the monomer (a).

In the present invention, the (co)polymer (A) preferably contains a (meth)acrylic acid alkyl ester (b) having an alkyl group having 1 to 4 carbon atoms as a constituent monomer.
Examples of alkyl groups having 1 to 4 carbon atoms include methyl group, ethyl group, propyl group (n-propyl group, isopropyl group, etc.), butyl group (e.g., n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, etc.).
Among these, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature, an alkyl group having 2 to 4 carbon atoms is preferable, and a combination of an ethyl group and/or a propyl group and a butyl group is more preferable, and particularly preferable. is a combination of an ethyl group and/or an n-propyl group and an n-butyl group, particularly preferably a combination of an ethyl group and an n-butyl group.

(Meth)acrylic acid alkyl ester (b) includes, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate and the like.
Among these, at least one selected from the group consisting of ethyl (meth)acrylate, propyl (meth)acrylate and butyl (meth)acrylate is preferable, more preferably, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. The combination of ethyl (meth)acrylate and/or propyl (meth)acrylate and butyl (meth)acrylate is particularly preferred, and the combination of ethyl (meth)acrylate and butyl (meth)acrylate is particularly preferred.
When the (co)polymer (A) has a side chain having a polyolefin structure with low polarity (SP value), (A) contains butyl (meth)acrylate with high polarity (SP value) as a constituent monomer. , the behavior of polymer chains (polyolefin side chains aggregate to cover butyl (meth)acrylate, which is highly polar with respect to the base oil, at low temperatures, and the polyolefin structure expands at high temperatures) tends to be more temperature dependent. Therefore, it is preferable. In addition, by including ethyl (meth) acrylate and / or propyl (meth) acrylate having a higher polarity (SP value) than butyl (meth) acrylate as a constituent monomer, aggregation at low temperature in the base oil of (A) It is speculated that the force can be higher and the low temperature (eg 40° C.) viscosity can be lower. Ethyl (meth)acrylate and/or propyl (meth)acrylate are also not too polar (SP value) compared to methyl (meth)acrylate, can spread at high temperatures and have high temperature (e.g. 100°C) viscosity can be increased.

When the (co)polymer (A) contains ethyl (meth)acrylate and/or propyl (meth)acrylate and butyl (meth)acrylate as constituent monomers, the constituent monomers of the (co)polymer (A) The weight ratio ( _{X 2-3} /X 4 ) of the total weight of ethyl (meth)acrylate and propyl (meth)acrylate in the body (X _2-3 ) and the weight of butyl (meth)acrylate (X ₄ ) is From the viewpoint of increasing the molecular behavior of (A) with respect to temperature and the solubility in the base oil, the lower limit is preferably 0.1 or more, more preferably 0.2 or more, and particularly preferably 0.3 or more. The upper limit is preferably 1.0 or less, more preferably 0.9 or less, and particularly preferably 0.85 or less.

When the (co)polymer (A) contains ethyl (meth)acrylate and/or propyl (meth)acrylate and a monomer (a) as constituent monomers, the constituent units of the (co)polymer (A) Weight ratio (X _2-3 /X a) of the total weight (X _2-3 ) of ethyl (meth)acrylate and propyl (meth)acrylate in the monomer and the weight (X _a ) of the monomer (a ₎ ) has a lower limit of preferably 0.6 or more, more preferably 0.7 or more, and particularly preferably 1.5 from the viewpoint of increasing the molecular behavior of (A) with respect to temperature and solubility in base oil. It is 0 or more, and the upper limit is preferably 2.5 or less, more preferably 2.2 or less, and particularly preferably 2.0 or less.

［一般式（２）においてＲ^３は水素原子又はメチル基；－Ｘ^２－は－Ｏ－又は－ＮＨ－で表される基；Ｒ^４は炭素数２～４のアルキレン基；Ｒ^５は炭素数１～８のアルキル基；ｑは１～２０の整数であり、ｑが２以上の場合のＲ^５は同一でも異なっていてもよい。］ In the present invention, the (co)polymer (A) preferably contains a monomer (c) represented by the following general formula (2) as a constituent monomer. Since the monomer (c) has a relatively high polarity (SP value), the use of (c) makes it possible to adjust the SP value of the (co)polymer (A) to a high value. One type of the monomer (c) may be used, or two or more types may be used in combination.

[In the general formula (2), R ³ is a hydrogen atom or a methyl group; -X ² - is a group represented by ^-O- or -NH-; R ⁴ is an alkylene group having 2 to 4 carbon atoms; an alkyl group of numbers 1 to 8; q is an integer of 1 to 20, and when q is 2 or more, R ⁵ may be the same or different; ]

R ³ in general formula (2) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of increasing the molecular behavior of (A) with respect to temperature.

—X ² — in general formula (2) is a group represented by —O— or —NH—. Among these, the group represented by —O— is preferable from the viewpoint of enhancing the molecular behavior of (A) with respect to temperature.

R ⁴ in general formula (2) is an alkylene group having 2 to 4 carbon atoms.
Examples of alkylene groups having 2 to 4 carbon atoms include ethylene group, isopropylene group, 1,2- or 1,3-propylene group, isobutylene group, and 1,2-, 1,3- or 1,4-butylene group. etc.
R ⁴ O is an alkyleneoxy group having 2 to 4 carbon atoms, and is an ethyleneoxy group, a 1,2- or 1,3-propyleneoxy group, and a 1,2-, 1,3- or 1,4-butyleneoxy group. and the like.
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 increasing the molecular behavior of (A) with respect to temperature. .
When q is 2 or more, R ⁴ O may be the same or different, and the bonding form of (R ⁴ O) _q moieties may be random or block.

R ⁵ in general formula (2) is an alkyl group having 1 to 8 carbon atoms. Linear or branched alkyl groups are included, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n- Examples include heptyl group, isoheptyl group, n-hexyl group, 2-ethylhexyl group, n-pentyl group and n-octyl group.
Among alkyl groups having 1 to 8 carbon atoms, alkyl groups having 1 to 7 carbon atoms are preferable from the viewpoint of increasing the molecular behavior of (A) with respect to temperature, and alkyl groups having 1 to 6 carbon atoms are more preferable. particularly preferred are alkyl groups having 1 to 5 carbon atoms, most preferred are alkyl groups having 2 or 4 carbon atoms.

Specific examples of the monomer (c) include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, pentyloxyethyl (meth)acrylate, hexyloxy ethyl (meth)acrylate, heptyloxyethyl (meth)acrylate, octyloxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, propoxypropyl (meth)acrylate, butoxypropyl (meth)acrylate, Pentyloxypropyl (meth)acrylate, hexyloxypropyl (meth)acrylate, heptyloxypropyl (meth)acrylate, octyloxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, propoxybutyl (meth)acrylate ) acrylate, butoxybutyl (meth)acrylate, pentyloxybutyl (meth)acrylate, hexyloxybutyl (meth)acrylate, heptyloxybutyl (meth)acrylate and octyloxybutyl (meth)acrylate, and alcohols having 1 to 8 carbon atoms Esterified product of (meth)acrylic acid and 2 to 20 moles of alkylene oxide having 2 to 4 carbon atoms (at least one selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide), N-methoxyethyl (Meth)acrylamide, N-ethoxyethyl(meth)acrylamide, N-butoxyethyl(meth)acrylamide and the like.
Of the monomers (c), ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate are preferred from the viewpoint of enhancing the molecular behavior of (A) with respect to temperature.
In the present invention, "(meth)acrylate" means "acrylate and/or methacrylate", and "(meth)acrylamide" means "acrylamide and/or methacrylamide".

［一般式（３）においてＲ^６は水素原子又はメチル基；－Ｘ^３－は－Ｏ－又は－ＮＨ－で表される基；Ｒ^７Ｏは炭素数２～４のアルキレンオキシ基；Ｒ^８及びＲ^９はそれぞれ独立に炭素数１～２４の直鎖アルキル基であり、Ｒ^８及びＲ^９の合計炭素数は７～３４；ｒは０～２０の整数であり、ｒが２以上の場合のＲ^７Ｏは同一でも異なっていてもよい。］ In the present invention, the (co)polymer (A) may contain a (meth)acryloyl monomer (d) having a linear or branched alkyl group having 9 to 36 carbon atoms as a constituent monomer. preferable. Containing the monomer (d) as a constituent monomer is preferable because the polarity (SP value) of the (co)polymer (A) can be moderately adjusted.
As the monomer (d), other than (a), a (meth)acryloyl monomer (d1) having a linear alkyl group having 9 to 36 carbon atoms and represented by the following general formula (3) (meth)acryloyl monomer (d2) having a branched alkyl group having 9 to 36 carbon atoms.
In addition, monomer (d) may use 1 type, and may use 2 or more types together.

[In general formula (3), R ⁶ is a hydrogen atom or ^a methyl group; -X ³ - is a group represented by -O- or -NH-; R ⁷ O is an alkyleneoxy group having 2 to 4 carbon atoms; and R ⁹ are each independently a linear alkyl group having 1 to 24 carbon atoms, the total number of carbon atoms of R ⁸ and R ⁹ is 7 to 34; r is an integer of 0 to 20, and r is 2 or more of R ⁷ O may be the same or different. ]

Examples of the (meth)acryloyl monomer (d1) having a linear alkyl group having 9 to 36 carbon atoms include (meth)acrylic acid alkyl ester {a linear alkyl alcohol having 9 to 36 carbon atoms and acrylic acid Esterified products such as n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-(meth)acrylate tridecyl, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, n-icosyl (meth)acrylate, (meth)acrylate n-docosyl acrylate, n-tetracosyl (meth)acrylate, n-triacontyl (meth)acrylate and n-hexatriacontyl (meth)acrylate}, alkylene of linear alkyl alcohol having 9 to 36 carbon atoms Oxide (C2-4) 1-20 mol adducts and (meth)acrylic acid esters, and (meth)acrylic acid alkylamides {amides of linear alkylamines having 9-36 carbon atoms and acrylic acid compound etc.}.
Of the monomers (d1), from the viewpoint of increasing the molecular behavior of (A) with respect to temperature, (meth)acrylic acid alkyl esters having a linear alkyl group having 12 to 28 carbon atoms are preferred, and more preferred. is a (meth)acrylic acid ester having a straight-chain alkyl group of 12 to 24 carbon atoms, and particularly preferred is a (meth)acrylic acid ester having a straight-chain alkyl group of 12 to 20 carbon atoms.
One type of the monomer (d1) may be used, or two or more types may be used in combination.

In monomer (d2), ^R6 in general formula (3) is a hydrogen atom or a methyl group. Among these, a methyl group is preferable from the viewpoint of enhancing the molecular behavior of (A) with respect to temperature.
—X ³ — in general formula (3) is a group represented by —O— or —NH—. Among these, the group represented by —O— is preferable from the viewpoint of improving the viscosity index.
R ⁷ in general formula (3) is an alkylene group having 2 to 4 carbon atoms. Examples of alkylene groups having 2 to 4 carbon atoms include ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene and 1,2-, 1,3- or 1,4-butylene. groups.
R ⁹ O is an alkyleneoxy group having 2 to 4 carbon atoms, such as ethyleneoxy group, 1,2- or 1,3-propyleneoxy group, and 1,2-, 1,3- or 1,4- butyleneoxy group and the like.
r in the general formula (3) is an integer of 0 to 20, preferably an integer of 0 to 5, more preferably an integer of 0 to 2, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature.
R ⁷ O when r is 2 or more may be the same or different, and the (R ⁷ O) _r moieties may be a random bond or a block bond.
R ⁸ and R ⁹ in general formula (3) are each independently a linear alkyl group having 1 to 24 carbon atoms. Specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-heptyl group, n-hexyl group, n-pentyl group, n-octyl group, n-nonyl group, n-decyl group , n-undecyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-eicosyl group and n-tetracosyl group. From the viewpoint of improving the viscosity index, at least one of R ⁸ and R ⁹ in general formula (3) is preferably a linear alkyl group having 6 to 24 carbon atoms, more preferably at least R ⁸ and R ⁹ One of them is a straight-chain alkyl group having 6 to 20 carbon atoms, and particularly preferably at least one of R ⁸ and R ⁹ is a straight-chain alkyl group having 8 to 16 carbon atoms.
The total carbon number of R ⁸ and R ⁹ is 7 to 34, preferably 8 to 30, more preferably 10 to 30, from the viewpoint of enhancing the molecular behavior of (A) with respect to temperature.

Specific examples of the monomer (d2) include 2-octyldecyl (meth)acrylate, an ester of ethylene glycol mono-2-octylpentadecyl ether and (meth)acrylic acid, and 2-(meth)acrylic acid. n-octyldodecyl, 2-n-decyltetradecyl (meth)acrylate, 2-n-dodecylhexadecyl (meth)acrylate, 2-n-tetradecyloctadecyl (meth)acrylate, (meth)acrylic acid 2 -n-dodecylpentadecyl, 2-n-tetradecylheptadecyl (meth)acrylate, 2-n-hexadecylheptadecyl (meth)acrylate, 2-n-heptadecylicosyl (meth)acrylate, ( 2-n-hexadecyl docosyl meth)acrylate, 2-n-eicosyl docosyl (meth) acrylate, 2-n-tetracosylhexacosyl (meth) acrylate and N-2-octyldecyl ( meth) acrylamide and the like.
As the monomer (d2), from the viewpoint of increasing the molecular behavior of (A) with respect to temperature, 2-n-decyldodecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, (meth) ) 2-n-decylhexadecyl acrylate, 2-n-decyloctadecyl (meth)acrylate, 2-n-dodecyltetradecyl (meth)acrylate, 2-n-dodecylhexadecyl (meth)acrylate, ( 2-n-dodecyloctadecyl (meth)acrylate and 2-n-tetradecylhexadecyl (meth)acrylate are preferred, more preferably 2-n-decyltetradecyl (meth)acrylate and 2-(meth)acrylate n-dodecylhexadecyl and 2-n-tetradecylhexadecyl (meth)acrylate.
One type of the monomer (d2) may be used, or two or more types may be used in combination.

As the monomer (d), an ester of (meth)acrylic acid and a mixture of alcohols having a linear or branched alkyl group of 9 to 36 carbon atoms may be used. Mixtures of alcohols include, for example, non-ethoxylated linear C 9-17 primary alcohol mixtures sold by Shell Company under the trade name NEODOL (e.g., NEODOL 23, NEODOL 91). , NEODOL 25, NEODOL 45, NEODOL 135, NEODOL 67 and NEODOL 1, etc.), the ethoxylates of said NEODOL (after the product name of said alcohol mixture, carrying a number indicating the average number of moles of ethylene oxide added) For example, NEODOL 23-1, NEODOL 23-3, NEODOL 23-6.5, NEODOL 23-2, NEODOL 91-8, NEODOL 91-2.5, NEODOL 91-5, NEODOL 91-6, NEODOL 25-2.5, NEODOL 25-3, NEODOL 25-7, NEODOL 25-9, NEODOL 25-5, NEODOL 25-1.3, NEODOL 45-4, NEODOL 45-7, NEODOL 45-6.8 and NEODOL 1-9, etc.).
Among these, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature, (meth)acrylic acid esters of non-ethoxylated linear primary alcohol mixtures having 9 to 17 carbon atoms are preferred, and NEODOL 23 is more preferred. , NEODOL 25 and NEODOL 45.

In the present invention, the (co)polymer (A) includes a nitrogen atom-containing monomer (e), a hydroxyl group-containing monomer (f), and a phosphorus atom, excluding the monomers (a) to (d). Containing monomer (g), aliphatic hydrocarbon monomer (h), alicyclic hydrocarbon monomer (i), aromatic hydrocarbon monomer (j), vinyl compound (k), epoxy At least one selected from the group consisting of group-containing monomers (l), halogen element-containing monomers (m) and unsaturated polycarboxylic acid esters (n) may be included as a constituent monomer.

Examples of the nitrogen atom-containing monomer (e) include the following monomers (e1) to (e4).
Amido group-containing monomer (e1):
(Meth)acrylamide, monoalkylamino (meth)acrylamide [one in which one alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom; for example, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N- Isopropyl (meth)acrylamide and Nn- or isobutyl (meth)acrylamide, etc.], monoalkylaminoalkyl (meth)acrylamide [aminoalkyl group in which one alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom (carbon number 2 to 6); for example N-methylaminoethyl (meth)acrylamide, N-ethylaminoethyl (meth)acrylamide, N-isopropylamino-n-butyl (meth)acrylamide and Nn- or isobutylamino- n-butyl (meth)acrylamide, etc.], dialkylamino (meth)acrylamide [those in which two alkyl groups having 1 to 4 carbon atoms are bonded to a nitrogen atom; for example, N,N-dimethyl (meth)acrylamide, N,N- diethyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide and N,N-di-n-butyl (meth)acrylamide], dialkylaminoalkyl (meth)acrylamide [alkyl having 1 to 4 carbon atoms on the nitrogen atom Those having an aminoalkyl group (having 2 to 6 carbon atoms) in which two groups are bonded; for example, N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylamino propyl (meth)acrylamide and N,N-di-n-butylaminobutyl (meth)acrylamide, etc.], N-vinylcarboxylic acid amide [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionyl amide, N-vinylhydroxyacetamide, etc.] and those having a nitrogen atom only in the amide group.

Nitro group-containing monomer (e2):
4-nitrostyrene and the like.

Primary to tertiary amino group-containing monomer (e3):
Primary amino group-containing monomers {alkenylamines having 3 to 6 carbon atoms [(meth)allylamine, crotylamine, etc.], aminoalkyl (carbon atoms 2 to 6) (meth)acrylates [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.], dialkenylamine having 6 to 12 carbon atoms [di(meth)allylamine, etc.]}; tertiary amino group-containing monomer body {dialkylaminoalkyl (meth)acrylate [those having an aminoalkyl group (2 to 6 carbon atoms) in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom; ) acrylates and N,N-diethylaminoethyl (meth)acrylate, etc.], alicyclic (meth)acrylates having a nitrogen atom [morpholinoethyl (meth)acrylate, etc.], aromatic monomers [N-(N', N′-diphenylaminoethyl)(meth)acrylamide, N,N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone and N-vinylthiopyrrolidone, etc.]}, and Hydrochlorides, sulfates, phosphates, or lower alkyl (C1-8) monocarboxylic acid (acetic acid, propionic acid, etc.) salts thereof are included.

Nitrile group-containing monomer (e4):
(Meth)acrylonitrile and the like.

Among the monomers (e), preferred are (e1) and (e3), more preferred are N-(N',N'-diphenylaminoethyl)(meth)acrylamide, N-(N' , N'-dimethylaminoethyl) (meth)acrylamide, N-(N',N'-diethylaminoethyl) (meth)acrylamide, N-(N',N'-dimethylaminopropyl) (meth)acrylamide, N, N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate.

Hydroxyl group-containing monomer (f):
Hydroxyl group-containing aromatic monomer (p-hydroxystyrene, etc.), hydroxyalkyl (C2-C6) (meth)acrylate [2-hydroxyethyl (meth)acrylate, and 2- or 3-hydroxypropyl (meth)acrylate etc.], mono- or bis-hydroxyalkyl (1 to 4 carbon atoms) substituted (meth)acrylamide [N,N-bis(hydroxymethyl)(meth)acrylamide, N,N-bis(hydroxypropyl)(meth)acrylamide , N,N-bis(2-hydroxybutyl) (meth)acrylamide, etc.], vinyl alcohol, alkenols having 3 to 12 carbon atoms [(meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1 -undecenol, etc.], alkene monools or alkenediols having 4 to 12 carbon atoms [1-butene-3-ol, 2-buten-1-ol and 2-butene-1,4-diol, etc.], hydroxyalkyls (carbon Numbers 1-6) Alkenyl (C 3-10) ethers (2-hydroxyethyl propenyl ether, etc.), polyhydric (tri- to octahydric) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars and 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, degree of polymerization 2 to 50), polyoxyalkylene polyol [polyoxyalkylene ether of the above tri- to octahydric alcohol (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 100)], mono (meth) acrylate of polyoxyalkylene glycol or alkyl (carbon number 1 to 4) ether of polyoxyalkylene polyol [polyethylene glycol (Mn: 100 to 300) mono (meth) acrylate, polypropylene glycol ( Mn: 130-500) mono(meth)acrylate, methoxypolyethylene glycol (Mn: 110-310) (meth)acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth)acrylate and mono(meth)acrylic acid polyoxyethylene (Mn: 150 to 230) sorbitan, etc.] and the like;

Examples of the phosphorus atom-containing monomer (g) include the following monomers (g1) to (g2).

Phosphate ester group-containing monomer (g1):
(Meth)acryloyloxy alkyl (C2-C4) phosphate [(meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate] and alkenyl phosphate [vinyl phosphate, allyl phosphate, propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, dodecenyl phosphate, etc.] and the like.

Phosphono group-containing monomer (g2):
(Meth)acryloyloxyalkyl (2-4 carbon atoms) phosphonic acid [(meth)acryloyloxyethyl phosphonic acid, etc.] and alkenyl (2-12 carbon atoms) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid and octenyl phosphonic acid etc.] and the like.

Among the phosphorus atom-containing monomers (g), (g1) is preferable, and (meth)acrylic is more preferable from the viewpoint of copolymerizability with other monomers and solubility in base oil. Loyloxyalkyl (C2-4) phosphate esters, and (meth)acryloyloxyethyl phosphate is particularly preferred.

Aliphatic hydrocarbon monomer (h):
Alkenes with 2 to 20 carbon atoms (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.) and alkadiene with 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1 , 6-heptadiene and 1,7-octadiene).

Alicyclic hydrocarbon monomer (i):
cyclohexene, (di)cyclopentadiene, pinene, limonene, vinylcyclohexene, ethylidenebicycloheptene and the like.

Aromatic hydrocarbon-based monomer (j):
Styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, indene, 4 -crotylbenzene and 2-vinylnaphthalene.

Vinyl compounds (vinyl esters, vinyl ethers, vinyl ketones) (k):
Vinyl esters of saturated fatty acids with 2 to 12 carbon atoms (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, etc.), alkyl, aryl or alkoxyalkyl vinyl ethers with 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 (l):
glycidyl (meth)acrylate, glycidyl (meth)allyl ether, and the like.

Halogen-containing monomer (m):
Examples include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrene (dichlorostyrene, etc.).

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

The ratio of the monomer (a) constituting the (co)polymer (A) is determined from the viewpoint of increasing the molecular behavior of (A) with respect to temperature and the solubility in the base oil. It is preferably 10 to 20% by weight, more preferably 10 to 17% by weight, particularly preferably 12 to 15% by weight, based on the total weight of the polymer.
From the viewpoint of increasing the molecular behavior of (A) with respect to temperature, the ratio of the monomer (b) constituting (A) is preferably 40 to 40, based on the total weight of the monomers constituting (A). 85% by weight, more preferably 40 to 80% by weight, particularly preferably 42 to 74% by weight.
From the viewpoint of increasing the molecular behavior of (A) with respect to temperature, the ratio of the monomer (c) constituting (A) is preferably 5 to 5, based on the total weight of the monomers constituting (A). 40% by weight, more preferably 8 to 38% by weight, particularly preferably 10 to 35% by weight.
From the viewpoint of increasing the molecular behavior of (A) with respect to temperature, the ratio of the monomer (d) constituting (A) is preferably 2 to 2, based on the total weight of the monomers constituting (A). 20% by weight, more preferably 3 to 18% by weight, particularly preferably 5 to 14% by weight.
From the viewpoint of increasing the molecular behavior of (A) with respect to temperature, the total content of the monomers (e) to (g) constituting (A) is the total weight of the monomers constituting (A). Based on the above, it is preferably 15% by weight or less, more preferably 10% by weight or less.
The total content of the monomers (h) to (n) constituting (A) is preferably 10, based on the total weight of the monomers constituting (A), from the viewpoint of improving the viscosity index. % by weight or less, more preferably 7% by weight or less.
The total weight ratio of the monomers (a) and (b) constituting (A) is based on the total weight of the monomers constituting (A) from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. , preferably 50 to 95% by weight, more preferably 50 to 90% by weight, particularly preferably 54 to 86% by weight.
The total weight ratio of the monomers (c) and (d) constituting (A) is based on the total weight of the monomers constituting (A) from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. , preferably 5 to 50% by weight, more preferably 10 to 50% by weight, particularly preferably 14 to 46% by weight.

The SP value of the (co)polymer (A) is preferably 9.1 to 9.5 (cal/cm ³ ) ^1/2 , more preferably 9.2 to 9.5 (cal/cm ³ ) ^{1/ 2} , and particularly preferably 9.3 to 9.5 (cal/cm ³ ) ^1/2 . The SP value of the (co)polymer (A) tends to improve the behavior of the polymer chain (cohesion at low temperature and spreading at high temperature) when the difference between the SP value of the (co)polymer (A) and the base oil is increased within the range of solubility in the base oil. , means that it tends to dissolve in the base oil if it is less than the above upper limit, and that the behavior of the polymer chain tends to be good if it is more than the above lower limit.

In addition, the SP value of the (co)polymer (A) in the case of a copolymer consisting of two or more monomers is obtained by The SP value of each monomer (constituent unit with a single bond) is calculated by the above method, and the SP value of each monomer (constituent unit with a carbon-carbon double bond as a single bond) is calculated as the constituent monomer. It is an arithmetic mean value calculated based on the weight fraction of the unit. The SP value of (A) can be adjusted by appropriately adjusting the SP value and weight fraction of the monomer used (constituent unit in which carbon-carbon double bonds are single bonds).
For example, when the monomer is methyl methacrylate, the constitutional unit derived from methyl methacrylate has 2 _CH3 , 1 _CH2 , 1 C, and ₁ CO2 as atomic groups. From the following formula, it can be seen that the SP value of the structural unit derived from methyl methacrylate is 9.933 (cal/cm ³ ) ^1/2 . A similar calculation reveals that the SP value of the structural unit derived from ethyl methacrylate is 9.721 (cal/cm ³ ) ^1/2 .
ΣΔe _i =1125×2+1180+350+4300=8080
Σv _i =33.5×2+16.1−19.2+18.0=81.9
δ=(8080/81.9) ^1/2 =9.933 (cal/cm ³ ) ^1/2
When the copolymer is a polymer of 50% by weight of methyl methacrylate and 50% by weight of ethyl methacrylate, the SP value of the copolymer is the weight of the SP value of the structural unit derived from each monomer as follows. Calculated by arithmetic averaging based on fractions.
SP value of the copolymer = (9.933 × 50 + 9.721 × 50) / 100 = 9.827
Further, when two or more (co)polymers (A) are used, the weight fraction is calculated based on the SP value of each (co)polymer (A), and the arithmetic average value is the above SP value. is preferably satisfied.

Mw of the (co)polymer (A) is preferably 100,000 to 1,000,000, more preferably 200,000 to 800,000, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. , particularly preferably 300,000 to 700,000, most preferably 400,000 to 600,000. Mw of (A) can be measured by GPC under the above conditions.

The (co)polymer (A) can be obtained by a known production method, specifically a method of solution polymerization of the above monomers 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, ethyl acetate, 2-propanol, base oil (ester oil, mineral oil, etc.) and the like.
Polymerization catalysts include azo catalysts (azobisisobutyronitrile, azobisvaleronitrile, etc.), peroxide catalysts (benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.) and redox catalysts (benzoyl peroxide and a mixture of tertiary amines, etc.). Further, if necessary, a known chain transfer agent (alkylmercaptan having 2 to 20 carbon atoms, etc.) can be used.
The polymerization temperature is preferably 25-140°C, more preferably 50-120°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 form of polymerization may be either a random addition polymer or an alternating copolymer, and may be either a graft copolymer or a block copolymer.

In addition to the (co)polymer (A), the lubricating oil composition of the present invention may further contain a (meth)acrylic acid alkyl ester (co)polymer (C) other than (A), It is preferable to contain the (co)polymer (C) from the viewpoint of low-temperature viscosity.
The (co)polymer (C) includes a (co)polymer that does not contain the monomer (a), such as an alkyl (meth)acrylate having a linear or branched alkyl group having 9 to 36 carbon atoms. Examples thereof include (co)polymers having an ester (d) as an essential constituent monomer. Specifically, n-dodecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate and n-octadecyl (meth)acrylate copolymer, n-(meth)acrylate -octadecyl/n-dodecyl (meth)acrylate (molar ratio 10 to 30/90 to 70) copolymer, n-tetradecyl (meth)acrylate/n-dodecyl (meth)acrylate (molar ratio 10 to 30/ 90-70) copolymer, n-hexadecyl (meth)acrylate/n-dodecyl (meth)acrylate/methyl (meth)acrylate (molar ratio 20-40/55-75/0-10) copolymer and n-dodecyl acrylate/n-dodecyl methacrylate (molar ratio 10 to 40/90 to 60) copolymers and the like, and these may be used alone or in combination of two or more.

The content of the (co)polymer (C) is preferably 0.01 to 30% by weight, more preferably 0.01 to 30% by weight, based on the weight of the (co)polymer (A), from the viewpoint of low-temperature viscosity. 10% by weight.

Mw of the (co)polymer (C) is preferably 5,000 to 100,000, more preferably 10,000 to 80,000, from the viewpoint of lowering the pour point temperature.
The SP value of the (co)polymer (C) is preferably 7.0 to 10, more preferably 8.0 to 9.5, from the viewpoint of solubility in the base oil.
The conditions for measuring the Mw of the (co)polymer (C) are the same as the conditions for measuring the Mw of the monomer (a).

<Ester oil (B)>
The lubricating oil composition of the present invention contains an ester oil (B).
By containing the ester oil (B) as the base oil, the behavior of the polymer chain of the (co)polymer (A) in the base oil (at low temperatures, the highly polar portion with respect to the base oil (e.g., ester group, etc.) The polyolefin chain aggregates so as to cover the , and the polyolefin chain spreads at high temperatures). It is assumed that it is possible to reduce the rolling friction coefficient (MTM friction coefficient). In addition, although the base oil used for the lubricating oil tends to have a high NOACK evaporation amount when the viscosity is low, the ester oil (B) has the same viscosity as the hydrocarbon oil, for example, but the intermolecular interaction due to the ester group Therefore, the NOACK evaporation amount tends to be low, and it is presumed that there is a tendency to easily adjust the HTHS viscosity to be low while reducing the NOACK evaporation amount.
One type of the ester oil (B) may be used, or two or more types may be used in combination. It is preferable to use two kinds together.

As the ester oil (B), an ester compound with a lubricating function that has been conventionally used as a lubricating oil can be used. A diester of a monohydric carboxylic acid (x2) and a dihydric alcohol (y2), an ester of a monohydric alcohol (y1) and a monohydric carboxylic acid (x2), a monohydric carboxylic acid (x2) and a trihydric or higher Examples thereof include an esterified product with a polyhydric alcohol (y3) and an esterified product with a trihydric or higher polycarboxylic acid (x3) and a monohydric alcohol (y1).
From the viewpoint of lowering the viscosity, the ester oil (B) is preferably a diester of a divalent carboxylic acid (x1) and a monohydric alcohol (y1), a monovalent carboxylic acid (x2) and a dihydric alcohol (y2 ) and an esterified product of a monohydric alcohol (y1) and a monovalent carboxylic acid (x2).

Examples of the divalent carboxylic acid (x1) include aliphatic dicarboxylic acids having 2 to 24 carbon atoms [linear saturated aliphatic dicarboxylic acids {e.g., ethanedioic acid (oxalic acid), propanedioic acid (malonic acid, ), n-butanedioic acid (succinic acid), n-heptanedioic acid (glutaric acid), n-hexanedioic acid (adipic acid), n-heptanedioic acid, n-octanedioic acid, n-nonanedioic acid ( azelaic acid), n-decanedioic acid (sebacic acid), n-undecanedioic acid, n-dodecanedioic acid, n-tridecanedioic acid, n-tetradecanedioic acid, n-pentadecanedioic acid and n-hexadecanedioic acid, etc. }, branched saturated aliphatic dicarboxylic acid {e.g., 3-methyladipic acid, etc.}, unsaturated aliphatic divalent carboxylic acid {e.g., maleic acid, fumaric acid, etc.}, alicyclic saturated divalent carboxylic acid {e.g., 1,2- or 1,3-cyclopentanedicarboxylic acid, 1,2-, 1,3- or 1,4-cyclohexanedicarboxylic acid, etc.}, aromatic ring-containing divalent having 8 to 24 carbon atoms Carboxylic acid {eg, phthalic acid, isophthalic acid, terephthalic acid, etc.} and the like.
Among these, from the viewpoint of lowering the viscosity, a linear saturated aliphatic dicarboxylic acid having 2 to 24 carbon atoms is preferable, more preferably a linear saturated aliphatic dicarboxylic acid having 6 to 15 carbon atoms. and particularly preferred are adipic acid and sebacic acid.

The monovalent carboxylic acid (x2) includes aliphatic monovalent carboxylic acids having 2 to 25 carbon atoms [linear saturated aliphatic monovalent carboxylic acids {e.g., n-propanoic acid, n-butanoic acid, n-pentanoic acid, , n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid , n-hexadecanoic acid, n-heptadecanoic acid, n-octadecanoic acid, n-nonadecanoic acid, eicosanoic acid, docosanoic acid and tetracosanoic acid}, branched saturated aliphatic monovalent carboxylic acids having 2 to 25 carbon atoms {for example , 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, isoundecanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isopentadecanoic acid, isohexadecanoic acid, isoheptadecanoic acid, isooctadecanoic acid and isononadecanoic acid}, alicyclic Monovalent carboxylic acid {eg, cyclohexanecarboxylic acid, etc.} etc.], aromatic ring-containing monovalent carboxylic acid {eg, benzoic acid etc.}, etc., can be mentioned.
Among these, branched saturated aliphatic monovalent carboxylic acids having 2 to 25 carbon atoms are preferred from the viewpoint of lowering the viscosity, more preferably branched saturated aliphatic monovalent carboxylic acids having 5 to 20 carbon atoms. 2-ethylhexanoic acid and isodecanoic acid are particularly preferred.

The monohydric alcohol (y1) includes aliphatic monoalcohols having 1 to 24 carbon atoms [linear saturated aliphatic monoalcohols {e.g., methanol, ethanol, n-propanol, n-butanol, n-pentanol, n- Hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecyl alcohol, n-dodecyl alcohol, n-tridecyl alcohol, n-tetradecyl alcohol, n-pentadecyl alcohol, n-hexa Decyl alcohol, n-heptadecyl alcohol, n-octadecyl alcohol, n-nonadecyl alcohol, n-icosanol, n-heneicosanol, n-docosanol and n-tetracosanol}, branched saturated aliphatic mono Alcohol {e.g., 2-ethylhexanol, isononyl alcohol, isodecyl alcohol, isoundecyl alcohol, isododecyl alcohol, isotridecyl alcohol, isotetradecyl alcohol, isopentadecyl alcohol, isohexadecyl alcohol, isoheptadecyl alcohol , isooctadecyl alcohol and isononadecyl alcohol, etc.}, alicyclic monoalcohols {for example, cyclohexanol, 2-, 3- or 4-t-butylcyclohexanol, menthol, cyclohexaneethanol, 2-, 3- or 4- isopropylcyclohexanol, etc.], aromatic ring-containing monoalcohols having 7 to 24 carbon atoms {eg, benzyl alcohol, etc.}, and the like.
Among these, branched saturated aliphatic monoalcohols having 1 to 24 carbon atoms are preferred from the viewpoint of lowering the viscosity, more preferably branched saturated aliphatic monoalcohols having 6 to 12 carbon atoms are particularly preferred. are 2-ethylhexyl alcohol and isodecyl alcohol.

The dihydric alcohol (y2) includes aliphatic dihydric alcohols having 2 to 24 carbon atoms [linear saturated aliphatic diols {eg, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12 -dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,15-pentadecanediol and 1,16-hexadecanediol, etc.}, branched saturated aliphatic diols {e.g., 2-methyl-1 , 3-propanediol, 2-methyl-1,4-butanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 3-methyl-1,5-pentanediol, 1 ,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2-undecanediol, 1,2-dodecanediol, 1,2-tridecanediol, 1 , 2-tetradecanediol, 1,2-pentadecanediol and 1,2-hexadecanediol, etc.}, alicyclic diols {e.g., 1,2-, 1,3- or 1,4-cyclohexanediol, etc.}, etc.], Examples thereof include aromatic ring-containing dihydric alcohols having 8 to 24 carbon atoms {eg, ethylene oxide adducts of dihydroxybenzene, etc.}.
Among these, from the viewpoint of lowering viscosity, linear saturated aliphatic diols having 2 to 24 carbon atoms are preferable, linear saturated aliphatic diols having 4 to 10 carbon atoms are more preferable, and 1 , 6-hexanediol.

As the ester oil (B), from the viewpoint of lowering the viscosity, a diester product of a dihydric carboxylic acid (x1) and a monohydric alcohol (y1) is preferable, more preferably a linear saturated fat having 6 to 15 carbon atoms. is a diester of a group divalent carboxylic acid and a branched saturated aliphatic monoalcohol having 6 to 12 carbon atoms, particularly preferably bis(2-ethylhexyl) adipate and/or bis(2-ethylhexyl sebacate) ).
The ester oil (B) is preferably an ester compound having 10 to 40 carbon atoms, more preferably an ester compound having 15 to 35 carbon atoms, from the viewpoint of lowering the viscosity.

The SP value of the ester oil (B) is preferably 8.1 to 10.1 (cal/cm ³ ) ^1/2 , more preferably 8.2, from the viewpoint of the solubility of the (co)polymer (A). 9.5 (cal/cm ³ ) ^1/2 , particularly preferably 8.4 to 9.2 (cal/cm ³ ) ^1/2 .
When two or more ester oils (B) are used, the SP value and weight fraction of each ester oil are calculated, and the arithmetic average value preferably satisfies the above SP value.

The kinematic viscosity of the ester oil (B) at 100° C. (measured according to JIS-K2283) (unit: mm ² /s, abbreviated hereinafter) is preferably 2.0 to 4.0 from the viewpoint of reducing fuel consumption. It is more preferably 2.0 to 3.5. When multiple kinds of ester oils (B) are included, the 100° C. kinematic viscosity of the mixture is preferably within the above range.
When two types of ester oils (B) are used in combination, from the viewpoint of reducing fuel consumption and moderate NOACK transpiration amount, an ester oil having a kinematic viscosity at 100 ° C. of 1.00 to 2.50 mm ^/ s and a kinematic viscosity at 100 ° It is preferable to use an ester oil having a viscosity of 2.51 to 5.00 mm ² /s, more preferably an ester oil having a kinematic viscosity at 100°C of 2.00 to 2.50 mm ² /s and a kinematic viscosity at 100°C. It is used in combination with an ester oil having a viscosity of 3.00 to 4.00 mm ² /s.
As the lubricating oil composition, the kinematic viscosity of the ester oil (B) at 100 ° C. is in the above range, based on the weight of the ester oil (B) contained in the lubricating oil composition. more preferably 90% by weight or more, particularly preferably 95% by weight or more.
The kinematic viscosity at 100° C. of the ester oil (B) can be adjusted by adjusting the carbon number and the degree of branching of the carboxylic acid and the alcohol when synthesizing (B). is higher, and the kinematic viscosity tends to be lower if one with a smaller number of carbon atoms is used. Further, those with a small degree of branching tend to have high kinematic viscosity, and those with a large degree of branching tend to have low kinematic viscosity.

The kinematic viscosity of the ester oil (B) at 40° C. (measured according to JIS-K2283) (unit: mm ² /s, abbreviated hereinafter) is preferably 5.0 to 20.0 from the viewpoint of reducing fuel consumption. It is more preferably 7.0 to 15.0.
The kinematic viscosity of the ester oil (B) at 40° C. can be adjusted by adjusting the carbon number and branching degree of the carboxylic acid and the alcohol when synthesizing (B). is higher, and the kinematic viscosity tends to be lower if one with a smaller number of carbon atoms is used. Further, those with a small degree of branching tend to have high kinematic viscosity, and those with a large degree of branching tend to have low kinematic viscosity.

As the ester oil (B), specifically, a diester of a dihydric carboxylic acid (x1) and a monohydric alcohol (y1) {for example, bis(2-ethylhexyl) sebacate (100° C. kinematic viscosity: 3.2, 40°C kinematic viscosity: 11.6), bis(2-ethylhexyl) dodecanedioate (100°C kinematic viscosity: 3.7, 40°C kinematic viscosity: 13.7), ditridecyldodecanedioic acid (100°C kinematic viscosity: 5.1, 40° C. kinematic viscosity: 24.0), bis(2-ethylhexyl) adipate (100° C. kinematic viscosity: 2.3, 40° C. kinematic viscosity: 7.7), bis azelate (2- ethylhexyl) (100°C kinematic viscosity: 3.0, 40°C kinematic viscosity: 10.4), 2-ethylhexyl-n-octyl azelate (100°C kinematic viscosity: 3.1, 40°C kinematic viscosity: 10.8) , 2-ethylhexyl-n-octyl sebacate (100°C kinematic viscosity: 3.6, 40°C kinematic viscosity: 11.7), diisodecyl adipate (100°C kinematic viscosity: 3.6, 40°C kinematic viscosity: 14.4) etc.}, a diester of a monohydric carboxylic acid (x2) and a dihydric alcohol (y2) {for example, bis(octanoic acid)-3-methyl 1,5-pentanediyl (100° C. kinematic viscosity: 2.41 , 40 ° C kinematic viscosity: 7.4), bis (nonanoic acid) -3-methyl 1,5-pentanediyl (100 ° C kinematic viscosity: 2.7, 40 ° C kinematic viscosity: 8.9), bis (decanoic acid) -3-methyl 1,5-pentanediyl (100°C kinematic viscosity: 3.2, 40°C kinematic viscosity: 10.7), diester of neopentyl glycol and isooctanoic acid (100°C kinematic viscosity: 2.9, 40°C kinematic viscosity: 11.4), diesters of neopentyl glycol and 2-ethylhexanoic acid (100°C kinematic viscosity: 2.1, 40°C kinematic viscosity: 7.5), etc.}, monohydric alcohol (y1) and monoesters with a carboxylic acid (x2) {for example, isooctanol oleate (100°C kinematic viscosity: 2.7, 40°C kinematic viscosity: 8.3), etc.} and the like.

The viscosity index (measured according to JIS-K2283) of the ester oil (B) is preferably 90 or more, more preferably 100 or more, from the viewpoint of improving the viscosity index of the lubricating oil composition.

The cloud point (as measured by JIS-K2269) of the ester oil (B) is preferably -5°C or lower, more preferably -15°C or lower. When the cloud point of the ester oil (B) is within this range, the low-temperature viscosity of the lubricating oil composition tends to be good.

<Base oil (G)>
The lubricating oil composition of the present invention may contain a base oil (G) other than the ester oil (B).
As the base oil (G), for example, hydrocarbon oil {mineral oil (solvent refined oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil obtained by hydrocracking isoparaffin, naphthenic oil, hydrocarbon Synthetic lubricating oils (polyα-olefin synthetic lubricating oils, GTL base oils, etc.), non-hydrocarbon synthetic oils (ether synthetic lubricating oils, silicone synthetic lubricating oils, etc.), and mixtures thereof. Of these, hydrocarbon oils are preferred from the viewpoint of the solubility of the (co)polymer (A), and mineral oils, poly-α-olefin synthetic lubricating oils, and GTL base oils are more preferred.

The 40° C. kinematic viscosity (mm ² /s) of the base oil (G) is preferably 10-25, more preferably 12-20, from the viewpoint of reducing fuel consumption.
The 100° C. kinematic viscosity (mm ² /s) of the base oil (G) is preferably 2.0 to 5.0, more preferably 2.5 to 4.5, from the viewpoint of reducing fuel consumption.
The content of the base oil (G) in the lubricating oil composition is preferably 45 to 85% by weight, based on the weight of the lubricating oil composition, from the viewpoint of the solubility of the (co)polymer (A). It is preferably 48 to 83% by weight, particularly preferably 50 to 81% by weight.

The 40° C. kinematic viscosity (mm ² /s) of the base oil (ester oil (B) or mixture of (B) and base oil (G)) in the lubricating oil composition is 13.5 from the viewpoint of reducing fuel consumption. ~16.5 is preferable, and 13.8 to 16.3 is more preferable.
The 100° C. kinematic viscosity (mm ² /s) of the base oil (ester oil (B) or mixture of (B) and base oil (G)) in the lubricating oil composition is 3.0 from the viewpoint of reducing fuel consumption. ~4.0 is preferable, and 3.3 to 3.8 is more preferable.

The SP value {(cal/cm ³ ) ^1/2 } of the base oil (ester oil (B) or mixture of (B) and base oil (G)) in the lubricating oil composition is the (co)polymer ( From the viewpoint of solubility of A), it is preferably 8.3 to 8.7, more preferably 8.3 to 8.6, and particularly preferably 8.4 to 8.6.
When two or more kinds of base oils are used, it is preferable that the SP value of each base oil is calculated, and the arithmetic average value according to the weight fraction satisfies the above SP value.

<Additive>
The lubricating oil composition of the present invention contains detergents and/or dispersants and antioxidants.
In general, when a lubricating oil composition is used as an engine oil or the like, from the viewpoint of effects other than the MTM friction coefficient, which is the effect of the present invention (for example, oxidation stability, etc.), a detergent and / Or where it is essential to contain a dispersant and an antioxidant, when the HTHS viscosity at 150 ° C. is adjusted within a certain range without containing a detergent and / or a dispersant and an antioxidant Even if the kinematic viscosity at 100°C and the kinematic viscosity at 40°C are within the numerical ranges of the present invention, the kinematic viscosity at 100°C and the kinematic viscosity at 40°C can be reduced by adding a detergent and/or a dispersant and an antioxidant. becomes higher. On the other hand, in the present invention, when a detergent and/or dispersant and an antioxidant are contained, the HTHS viscosity at 150° C. is adjusted within a certain range while suppressing the NOACK evaporation amount to a low range. (60 to 100° C.) can be adjusted low, the MTM friction coefficient can be lowered, and the fuel consumption can be reduced.
"Containing a detergent and/or dispersant and an antioxidant" means including a detergent and an antioxidant, a dispersant and an antioxidant, or a detergent, a dispersant and an antioxidant. It is meant to include inhibitors. It may also be contained in the lubricating oil composition as a lubricating oil package additive in which a plurality of additives are blended.
In addition to detergents, dispersants and antioxidants, other additives such as oiliness improvers, friction and wear modifiers, extreme pressure agents, antifoam agents, demulsifiers, corrosion inhibitors, and at least one selected from the group consisting of pour point depressants).
Lubricating oil package additives containing detergents and/or dispersants and antioxidants include, for example, DI (Detergent Inhibitor) packages.
DI packages include products manufactured by Lubrizol Co., Ltd. {for example, LUBRIZOL PV series (product name PV1510, etc.) for gasoline vehicles}, products manufactured by INFINEUM {for example, Infinium P5741 for engine oil}, products manufactured by Chevron Corporation { For example, product names OLOA55501, OLOA55503, etc. for passenger car motor oil}, manufactured by Afton Chemical Co. {for example, HiTEC 9800 series for engine oil, etc.} are commercially available.

Examples of each component of the additive include the following.
(1) Detergency:
Basic, overbased or neutral metal salts [such as overbased or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzene sulfonates and alkylnaphthalene sulfonates, etc.)], salicylates, phenates, naphthenates , carbonates, phosphonates and mixtures thereof;
(2) Dispersant:
succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates and borates, etc.;
(3) Antioxidants:
hindered phenols and aromatic secondary amines;
(4) Oiliness improver:
Long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine and oleylamide, etc.), etc.;
(5) Pour point depressant polyalkyl methacrylate, ethylene-vinyl acetate copolymer, etc.;
(6) Friction and wear modifier:
molybdenum-based and zinc-based compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate, etc.);
(7) extreme pressure agent:
sulfur compounds (mono- or disulfides, sulfoxides and sulfur phosphide compounds), phosphide compounds and chlorine compounds (chlorinated paraffins, etc.);
(8) Defoamer:
Silicon oil, metallic soap, fatty acid ester and phosphate compound, etc.;
(9) Demulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphates (polyoxyethylene-containing nonionic surfactant phosphates, etc.), hydrocarbon solvents (toluene, xylene, ethylbenzene), etc.;
(10) metal deactivator nitrogen atom-containing compounds (benzotriazole, etc.), nitrogen atom-containing chelate compounds (N,N'-disalitidene-1,2-diaminopropane, etc.), nitrogen/sulfur atom-containing compounds (2-(n - dodecylthio) benzimidazole, etc.);
(11) Corrosion inhibitor:
nitrogen atom-containing compounds (benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate, etc.);

<Lubricating oil composition>
The lubricating oil composition of the present invention contains the (co)polymer (A), the ester oil (B), a detergent and/or dispersant and an antioxidant, and contains 150% of the lubricating oil composition. The HTHS (high temperature high shear) viscosity at ° C. is 2.55 to 2.80 mPa s, and the HTHS viscosity at 100 ° C. of the lubricating oil composition is 3.0 to 5.0 mPa s. A lubricating oil composition having an HTHS viscosity of 4.0 to 6.8 mPa s at 80 ° C., and a lubricating oil composition having an HTHS viscosity of 8.0 to 11.0 mPa s at 60 ° C. The NOACK evaporation amount of the product is 15-25% by weight.
The HTHS viscosity of the lubricating oil composition at 150 ° C. is 2.55 to 2.80 mPa s, which is the SAE specified 0W-20 {“0W” is the viscosity index at low temperature cold (when the engine is started) (Winter Grade), and "20" indicates the viscosity of the engine oil when the engine is warm.
In the present invention, although the lubricating oil composition contains additives that increase the viscosity such as detergents and / or dispersants and antioxidants, the (co)polymer (A) and the ester oil (B ), the HTHS viscosity at 60 to 100 ° C. when adjusting the HTHS viscosity at 150 ° C. is adjusted to the above range while keeping the NOACK evaporation amount of the lubricating oil composition as low as 15 to 25% by weight. As a result, the rolling friction coefficient in the fluid region at low temperatures (40 to 100° C.) can be reduced, contributing to the reduction of fuel consumption.

The HTHS viscosity of the lubricating oil composition at 150° C. (according to ASTM D4683) is 2.55-2.80 mPa·s.
The HTHS viscosity at 150 ° C. was obtained by applying shear to the lubricating oil composition at a high temperature of 150 ° C. in a narrow gap between metals, and the polymer chains of the (co)polymer (A) were oriented in the direction of flow and elongated. It is the viscosity of the state, and is adjusted by the content of (co)polymer (A), the molecular weight of (co)polymer (A), the SP value of (co)polymer (A), the viscosity of the contained base oil, etc. can do. For example, the content of (A) is reduced, the molecular weight of (A) is reduced, the SP value of the (co)polymer (A) is increased, the base oil with low viscosity (one with a small number of carbon atoms) etc.), the content of (A) can be increased, the molecular weight of (A) can be increased, the SP value of the (co)polymer (A) can be decreased, or the viscosity can be increased by using a base oil with a high .

The HTHS viscosity of the lubricating oil composition at 100° C. (according to ASTM D4683) is 3.0 to 5.0 mPa s, preferably 3.5 to 4.5 mPa s, more preferably 3.5 to 4.5 mPa s, from the viewpoint of reducing fuel consumption. is 3.8 to 4.3 mPa·s. When the HTHS viscosity at 100° C. exceeds 5.0 mPa·s, the rolling friction coefficient increases, and when it is less than 3.0 mPa·s, the NOACK evaporation amount increases.

The HTHS viscosity of the lubricating oil composition at 80° C. (according to ASTM D4683) is 4.0 to 6.8 mPa s, preferably 4.5 to 6.3 mPa s, more preferably 4.5 to 6.3 mPa s, from the viewpoint of reducing fuel consumption. is 5.5 to 6.1 mPa·s. When the HTHS viscosity at 80° C. exceeds 6.8 mPa·s, the rolling friction coefficient increases, and when it is less than 4.0 mPa·s, the NOACK evaporation amount increases.

The HTHS viscosity of the lubricating oil composition at 60° C. (according to ASTM D4683) is 8.0 to 11.0 mPa s, preferably 9.0 to 10.8 mPa s, more preferably 9.0 to 10.8 mPa s, from the viewpoint of reducing fuel consumption. is 10.0 to 10.5 mPa·s. When the HTHS viscosity at 60° C. exceeds 11.0 mPa·s, the rolling friction coefficient increases, and when it is less than 8.0 mPa·s, the NOACK evaporation amount increases.
The HTHS viscosities at 100°C, 80°C and 60°C are the HTHS viscosities at each temperature when the HTHS viscosity at 150°C is adjusted to the above range, and the (co)polymer (A) in the base oil. It can be adjusted by adjusting the ease of aggregation or spreading. For example, when a large number of highly polar monomers are used as the constituent monomers of (A) and the temperature is lowered, aggregation is facilitated, or the difference between the SP value of (A) and the SP value of the base oil is increased. It can be lowered by making it easier to aggregate when the temperature is lowered, and it is difficult to aggregate by using a large amount of monomers with low polarity as the constituent monomers of (A), or (A ) can be increased by reducing the difference between the SP value of the base oil and the SP value of the base oil to make aggregation difficult. Moreover, it can be lowered by using a base oil with low viscosity, and can be raised by using a base oil with high viscosity.

Specifically, a method of adjusting the SP value of (A) within the above range, a method of adjusting the molecular weight of (A), and determining the difference between the SP value of the (co)polymer (A) and the SP value of the base oil Examples include a method of adjusting the absolute value within the range described below, a method of adjusting the weight ratio (A/B) within the range described below, and a combination of these methods. In addition, a method of adjusting the weight ratio (X _2-3 /X ₄ ) to the above range, a method of adjusting the weight ratio (X _2-3 /X _a ) to the above range, a monomer constituting (A) ( When the method of adjusting the total weight ratio of a) and (b) within the above range is used, there is a tendency that (A) spreads further at 150°C, but aggregates at 60 to 100°C, resulting in greater molecular behavior.

The NOACK evaporation amount of the lubricating oil composition (measured by the method of ASTM D5800, the value measured at 250 ° C. for 1 hour) is 15 to 25% by weight from the viewpoint of damage to the engine due to the decrease in the volatile residue of the engine oil. It is preferably 17 to 25% by weight, more preferably 19 to 24% by weight.

The kinematic viscosity at 100° C. of the lubricating oil composition is preferably 6.9 to 9.3 mm ² /s, more preferably 6.9 to 8.5 mm ² /s, from the viewpoint of reducing fuel consumption. It is preferably 6.9 to 7.5 mm ² /s, then more preferably 7.0 to 7.5 mm ² /s.
The kinematic viscosity at 100 ° C. is the viscosity at 100 ° C. of the lubricating oil composition when the HTHS viscosity at 150 ° C. is adjusted to the above range, and when the kinematic viscosity of the base oil is the same, the base oil at 100 ° C. It can be adjusted by adjusting the ease of aggregation or spreading of the (co)polymer (A) in the medium. For example, by using a large number of highly polar monomers (for example, monomers (b) and (c)) as constituent monomers of (A) within the above range, the SP value of (A) is increased to facilitate aggregation. or by increasing the difference between the SP value of (A) and the SP value of the base oil within the range described later to facilitate aggregation. Further, within the above range, a monomer with low polarity (for example, monomer (a) or (d)) is used as a constituent monomer of (A) in large amounts to lower the SP value of (A) and make it difficult to aggregate. Alternatively, it can be increased by reducing the difference between the SP value of (A) and the SP value of the base oil within the range described below to make aggregation difficult. Moreover, it can be increased by increasing the content of a highly polar base oil (ester oil (B)) within the range described later and increasing the solubility of (A) at 100°C. If the difference between the SP value of (A) and the SP value of the base oil is too large, (A) becomes difficult to dissolve in the base oil, or (A) does not spread even at a high temperature of 150 ° C. The amount added when adjusting the HTHS viscosity in the is preferably within the range of Moreover, it can be lowered by using a large amount of base oil with low 100°C kinematic viscosity, and can be raised by using a large amount of base oil with high 100°C kinematic viscosity.

If the molecular weight of the (co)polymer (A) is increased, the amount of (A) added decreases, and the HTHS viscosity at 60 to 100°C tends to decrease. The thickening effect due to the increase in the molecular weight is greater than the decrease in viscosity due to the decrease in the molecular weight, and the kinematic viscosity tends to increase. Therefore, when the constituent monomers of (A) are the same, the kinematic viscosity (100° C.) can be increased and the HTHS viscosity (60 to 100° C.) can be lowered by adjusting the molecular weight.

The kinematic viscosity at 40° C. of the lubricating oil composition is preferably 20.0 to 23.8 mm ² /s, more preferably 20.2 to 23.8 mm ² /s, still more preferably from the viewpoint of reducing fuel consumption. 20.5 to 23.8 mm ² /s.
The kinematic viscosity at 40 ° C. is the viscosity at 40 ° C. of the lubricating oil composition when the HTHS viscosity at 150 ° C. is adjusted to the above range, and when the kinematic viscosity of the base oil is the same, the base oil at 40 ° C. It can be adjusted by adjusting the easiness of aggregation or spreading of the (co)polymer (A) therein. For example, a large number of highly polar monomers are used as constituent monomers of (A) to facilitate aggregation, or the difference between the SP value of (A) and the SP value of the base oil is increased to facilitate aggregation. can be lowered by In addition, a large number of monomers with low polarity are used as constituent monomers of (A) to make aggregation difficult, or the difference between the SP value of (A) and the SP value of the base oil is made small to make aggregation difficult. can be made higher. In addition, the NOACK evaporation amount can be reduced by using a large amount of base oil having a low kinematic viscosity at 40°C within the range of the amount that can be kept within the above range.

The ratio of the kinematic viscosity at 40 ° C. and the kinematic viscosity at 100 ° C. of the lubricating oil composition (40 ° C. kinematic viscosity / 100 ° C. kinematic viscosity) is preferably 2.5 to 3.5, more preferably from the viewpoint of reducing fuel consumption. is between 2.8 and 3.4, then more preferably between 2.9 and 3.3.
The ratio can be lowered, for example, by adjusting (A) in the lubricating oil composition so that it spreads at 100°C but aggregates at 40°C.

The viscosity index of the lubricating oil composition is preferably 280 or more, more preferably 285-380, further preferably 305-360, and particularly preferably 310-350, from the viewpoint of reducing fuel consumption.

The MTM friction coefficient of the lubricating oil composition (measurement temperature 100 ° C., measurement conditions below) is preferably 0.053 or less, more preferably 0.051 or less, and particularly preferably 0.050 from the viewpoint of reducing fuel consumption. It is below.
The MTM friction coefficient of the lubricating oil composition (measurement temperature 40 ° C., measurement conditions below) is preferably 0.060 or less, more preferably 0.058 or less, and particularly preferably 0.057 from the viewpoint of reducing fuel consumption. It is below.

The content of the (co)polymer (A) in the lubricating oil composition is, based on the weight of the lubricating oil composition, from the viewpoint of increasing the molecular behavior of (A) with respect to temperature and from the viewpoint of cost. 10% by weight is preferred, more preferably 0.1 to 5% by weight, still more preferably 0.5 to 4.0% by weight, and particularly preferably 0.8 to 3.5% by weight.
The content of the ester oil (B) in the lubricating oil composition is preferably 5 to 40% by weight, more preferably 8 to 40% by weight, based on the weight of the lubricating oil composition, from the viewpoint of fuel consumption reduction and cost. and particularly preferably 10 to 40% by weight.
The content of the base oil (G) in the lubricating oil composition is preferably 40 to 90% by weight, more preferably 45 to 85% by weight, based on the weight of the lubricating oil composition, from the viewpoint of fuel consumption reduction and cost. and particularly preferably 50 to 81% by weight.
The content of additives (total of detergents, dispersants, antioxidants and other additives) in the lubricating oil composition is 3, based on the weight of the lubricating oil composition, from the viewpoint of fuel consumption reduction and cost. ~12% by weight is preferred, 4 to 12% by weight is more preferred, and 5 to 12% by weight is particularly preferred.
The weight ratio (B/A) of the ester oil (B) and the (co)polymer (A) in the lubricating oil composition is preferably 3 to 20, more preferably 4 to 4, from the viewpoint of fuel consumption reduction and cost. 19, particularly preferably 4.5 to 18.5.
The weight ratio (A/G) between the (co)polymer (A) and the base oil (G) in the lubricating oil composition is preferably 0.01 to 0.05 from the viewpoint of fuel consumption reduction and cost, and further It is preferably 0.02 to 0.04, particularly preferably 0.025 to 0.045.
The weight ratio (B/G) between the ester oil (B) and the base oil (G) in the lubricating oil composition is preferably 0.1 to 1.0, more preferably 0, from the viewpoint of fuel consumption reduction and cost. 0.2 to 0.9, particularly preferably 0.2 to 0.8.

The absolute value of the difference {(cal/cm ³ ) ^1/2 } between the SP value of the (co)polymer (A) and the SP value of the ester oil (B) in the lubricating oil composition is (A) From the viewpoint of increasing the molecular behavior of the, it is preferably 0.2 to 0.7, more preferably 0.3 to 0.6.
When the lubricating oil composition contains the base oil (G), the SP value of the (co)polymer (A) and the SP value of the base oil {SP value of the ester oil (B) and the base oil (G) The absolute value {(cal/cm ³ ) ^1/2 } of the difference between the SP value and the arithmetic average value based on the weight fraction} is 0.6 from the viewpoint of increasing the molecular behavior of (A) with respect to temperature. ~1.1 is preferable, and 0.7 to 1.0 is more preferable.

The lubricating oil composition of the present invention can be suitably used as a lubricating oil composition for internal combustion engines, particularly a lubricating oil composition for hybrid vehicles.

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

<Production Example 1>
400 parts by weight of degassed and dehydrated hexane, 0.5 parts by weight of tetrahydrofuran, 90 parts by weight of 1,3-butadiene, and 0 part of n-butyllithium were placed in a 1 L SUS pressure-resistant reaction vessel equipped with a temperature controller and a stirrer. After charging 9 parts by weight, polymerization was carried out at a polymerization temperature of 50°C.
After the polymerization rate reached approximately 100%, 2 parts by weight of ethylene oxide was added and the mixture was reacted at 50° C. for an additional 3 hours. To stop the reaction, 50 parts by weight of water and 25 parts by weight of 1N-hydrochloric acid aqueous solution were added and stirred at 80° C. for 1 hour. The organic phase of the reaction solution was collected with a separating funnel, heated to 70° C., and the solvent was removed under reduced pressure of 0.027 to 0.040 MPa over 2 hours.
The obtained polybutadiene containing a hydroxyl group at one end was transferred to a reaction vessel equipped with a temperature control device, a stirrer and a hydrogen introduction tube, and 150 parts by weight of tetrahydrofuran was added to uniformly dissolve the polybutadiene. After pouring a suspension prepared by mixing 10 parts by weight of palladium carbon and 50 parts by weight of tetrahydrofuran in advance, the mixture was reacted at room temperature for 8 hours while supplying hydrogen into the liquid at a flow rate of 30 mL/min from the hydrogen introduction pipe. rice field. After that, palladium carbon is removed by filtration, and the resulting filtrate is heated to 70° C. and tetrahydrofuran is removed under reduced pressure of 0.027 to 0.040 MPa to remove hydrogenated polybutadiene one-end hydroxyl group-containing polymer (Y1). got
The molecular weight of the obtained (Y1) was measured by GPC, and the 1,2-butylene ratio was measured by ¹³ C-NMR. The results were Mw = 7,000, Mn = 6,500, 1,2-butylene ratio = 45 mol%, and molar ratio (1,2-adduct/1,4-adduct) = 45/55.

<Production Example 2>
400 parts by weight of degassed and dehydrated hexane, 2 parts by weight of tetrahydrofuran, 90 parts by weight of 1,3-butadiene, and 0.9 of n-butyllithium were placed in a 1 L SUS pressure-resistant reaction vessel equipped with a temperature controller and a stirrer. After charging the weight part, polymerization was carried out at a polymerization temperature of -0°C.
After the polymerization rate reached approximately 100%, 2 parts by weight of ethylene oxide was added and reacted at 50° C. for 3 hours. In order to stop the reaction, 50 parts by weight of water and 25 parts by weight of 1N-hydrochloric acid aqueous solution were added and stirred at 80° C. for 1 hour. The organic phase of the reaction solution was collected with a separating funnel, heated to 70° C., and the solvent was removed under reduced pressure of 0.027 to 0.040 MPa over 2 hours.
The obtained polybutadiene containing a hydroxyl group at one end was transferred to a reaction vessel equipped with a temperature control device, a stirrer and a hydrogen introduction tube, and 150 parts by weight of tetrahydrofuran was added to uniformly dissolve the polybutadiene. After pouring a suspension prepared by mixing 10 parts by weight of palladium carbon and 50 parts by weight of tetrahydrofuran in advance, the mixture was reacted at room temperature for 8 hours while supplying hydrogen into the liquid at a flow rate of 30 mL/min from the hydrogen introduction pipe. rice field. After that, palladium carbon is removed by filtration, and the obtained filtrate is heated to 70° C. and tetrahydrofuran is removed under reduced pressure of 0.027 to 0.040 MPa to remove hydrogenated polybutadiene having one terminal hydroxyl group (Y2). got
The molecular weight of the obtained (Y2) was measured by GPC, and the 1,2-butylene ratio was measured by ¹³ C-NMR. The results were Mw = 7,000, Mn = 6,500, 1,2-butylene ratio = 65 mol%, and molar ratio (1,2-adduct/1,4-adduct) = 65/35.

<Preparation of compositions containing (co)polymers (A-1) to (A-27) and (A'-1) to (A'-2)>
400 parts by weight of the hydrocarbon oil 1 described above and a total of 100 parts by weight of the monomer blends described in Tables 2 to 4 are placed in a reaction vessel equipped with a stirring device, a heating and cooling device, a thermometer, and a nitrogen inlet tube. 2,2-azobis (2,4-dimethylvaleronitrile), 2,2-azobis (2-methylbutyronitrile), t-butylperoxy-2-ethylhexyl monocarbonate as catalysts Table 2- 4, and after nitrogen substitution (gas phase oxygen concentration: 100 ppm), the temperature was raised to 76° C. while stirring in a sealed state, and the polymerization reaction was carried out at the same temperature for 4 hours. After heating to 120 to 130° C., unreacted monomers were removed over 2 hours under reduced pressure (0.027 to 0.040 MPa) at the same temperature, containing copolymer (A) and hydrocarbon oil 1. An additive composition was obtained. The SP value of the obtained copolymer (A) was calculated by the method described above, and the Mw was measured by the method described above.

<Examples 1 to 23, Comparative Examples 1 to 7>
Lubricating oil compositions were obtained by blending the (co)polymer (A)-containing composition obtained in the above preparation, other additives, and base oil in amounts shown in Tables 2 to 4. The content of the (co)polymer (A) in the table means the pure content of the (co)polymer (A) contained in the lubricating oil composition when the total amount of the lubricating oil composition is 100% by weight. (% by weight).

The compositions of monomers (a) to (f) listed in Tables 2 to 4 are as described below.
(a-1): Methacrylic acid ester of hydrogenated polybutadiene polymer containing hydroxyl group at one end obtained in Production Example 1 (ratio of 1,2-butylene = 45 mol%) (Y1) [Mn: 6,600]
(a-2): Methacrylic acid ester of hydrogenated polybutadiene polymer containing hydroxyl group at one end obtained in Production Example 2 (ratio of 1,2-butylene = 65 mol%) (Y2) [Mn: 6,600]
(a-3): One-end hydroxyl group-containing hydrogenated polybutadiene manufactured by CrayValley (Paris, France) [trade name; Krasol HLBH-5000M, 1,2-butylene ratio = 65 mol%, molar ratio isomer/1,4-adduct) = 65/35, crystallization temperature -60°C or less] and esterified product of methacrylic acid [Mn: 4,800]
(b-1): n-butyl methacrylate (b-2): methyl methacrylate (b-3): ethyl methacrylate (c-1): ethoxyethyl methacrylate (c-2): butoxyethyl methacrylate (d- 1): n-dodecyl methacrylate (Neodol 25 (manufactured by Shell Chemicals)
and methacrylic acid)
(d-2): A mixture of linear and branched alkyl methacrylates having 12 to 15 carbon atoms (Neodol 23 (manufactured by Shell Chemicals, a linear or branched alkyl alcohol having 12 to 13 carbon atoms (weight ratio = linear C12: branched C12: Straight chain C13: mixture of branched C13 = 40:10:40:10)) and esterified product of methacrylic acid)
(d-3): n-hexadecyl methacrylate (d-4): n-octadecyl methacrylate (d-5): 2-n-decyltetradecyl methacrylate (d-6): 2-n-dodecyl methacrylate Hexadecyl (d-7): 2-n-tetradecyl octadecyl methacrylate (f-1): styrene

The base oils and DI packages listed in Tables 2-4 are as follows.
Ester oil 1: bis(2-ethylhexyl) adipate (SP value: 8.9, kinematic viscosity at 100°C: 2.3 mm ² /s, kinematic viscosity at 40°C: 7.7 mm ² /s)
Ester oil 2: bis(2-ethylhexyl) sebacate (SP value: 8.9, kinematic viscosity at 100°C: 3.2 mm ² /s, kinematic viscosity at 40°C: 11.6 mm ² /s)
Ester oil 3: diisodecyl adipate (SP value: 8.9, kinematic viscosity at 100°C: 3.6 mm ² /s, kinematic viscosity at 40°C: 14.4 mm ² /s)
Hydrocarbon oil 1: SK Lubricants, product name “Yubase4”, Group III (SP value: 8.3, kinematic viscosity at 100°C: 4.2 mm ² /s, kinematic viscosity at 40°C: 19.6 mm ² /s )
Hydrocarbon oil 2: SK Lubricants, product name “Yubase3”, Group III (SP value: 8.3, kinematic viscosity at 100°C: 3.1 mm ² /s, kinematic viscosity at 40°C: 12.3 mm ² /s )
PV1510: DI package manufactured by Lubrizol Co., Ltd., package additive containing detergent, dispersant, antioxidant, etc. Infinium P5741: manufactured by INFINEUM, package additive containing detergent, dispersant, antioxidant, etc.

（１）の構造
ΣΔｅ_ｉ＝１１２５（ＣＨ_３）＋１１８０（ＣＨ_２）＋３５０（Ｃ）＋４３００（ＣＯ_２）＝６９５５
Σｖ_ｉ＝３３．５（ＣＨ_３）＋１６．１（ＣＨ_２）－１９．２（Ｃ）＋１８．０（ＣＯ_２）＝４８．４
（２）の構造
ΣΔｅ_ｉ＝１１８０（ＣＨ_２）×２＋８００（Ｏ）＝３１６０
Σｖ_ｉ＝１６．１（ＣＨ_２）×２＋３．８（Ｏ）＝３６
（３）の構造
ΣΔｅ_ｉ＝１１８０（ＣＨ_２）×２＋１１２５（ＣＨ_３）＋８２０（ＣＨ）＝４３０５
Σｖ_ｉ＝１６．１（ＣＨ_２）×２＋３３．５（ＣＨ_３）－１．０（ＣＨ）＝６４．７
（４）の構造
ΣΔｅ_ｉ＝１１８０（ＣＨ_２）×４＝４７２０
Σｖ_ｉ＝１６．１（ＣＨ_２）×４＝６４．４
ここで、１，２－ブチレン基及び１，４－ブチレン基の合計個数は下記である。
１，２－ブチレン基（（３）の構造）及び１，４－ブチレン基（（４）の構造）の合計個数＝（６６００－８６（（１）の構造）－４４（（２）の構造））／５６＝１１５．５５
したがって、（ａ－１）に由来する構成単位のパラメータは下記である。
ΣΔｅ_ｉ＝６９５５＋３１６０＋４３０５×１１５．５５×０．４５＋４７２０×１１５．５５×０．５５＝５３３９４８．２
Σｖ_ｉ＝４８．４＋３６＋６４．７×１１５．５５×０．４５＋６４．４×１１５．５５×０．５５＝７５４１．６４９７
ＳＰ値＝（ΣΔｅ_ｉ／Σｖ_ｉ）^１／２＝（５３３９４８．２／７５４１．６４９７）^１／２＝８．４１４ The SP value of a structural unit (structure in which a carbon-carbon double bond reacts to form a single bond) derived from each monomer was calculated based on the following formula.
Structural unit derived from (a-1)

Structure of (1) ΣΔe _i =1125( _CH3 )+1180( _CH2 )+350(C)+4300( _CO2 )=6955
Σv _i =33.5(CH ₃ )+16.1(CH ₂ )−19.2(C)+18.0(CO ₂ )=48.4
Structure of (2) ΣΔe _i =1180(CH ₂ )×2+800(O)=3160
Σv _i =16.1(CH ₂ )×2+3.8(O)=36
Structure of (3) ΣΔe _i =1180(CH ₂ )×2+1125(CH ₃ )+820(CH)=4305
Σv _i =16.1(CH ₂ )×2+33.5(CH ₃ )−1.0(CH)=64.7
Structure of (4) ΣΔe _i =1180(CH ₂ )×4=4720
Σv _i =16.1(CH ₂ )×4=64.4
Here, the total number of 1,2-butylene groups and 1,4-butylene groups is as follows.
Total number of 1,2-butylene groups (structure (3)) and 1,4-butylene groups (structure (4)) = (6600-86 (structure (1)) - 44 (structure (2) ))/56=115.55
Therefore, the parameters of the structural unit derived from (a-1) are as follows.
ΣΔe _i =6955+3160+4305×115.55×0.45+4720×115.55×0.55=533948.2
Σv _i =48.4+36+64.7×115.55×0.45+64.4×115.55×0.55=7541.6497
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(533948.2/7541.6497) ^1/2 =8.414

１，２－ブチレン基及び１，４－ブチレン基の合計個数＝（６６００－８５－４４）／５６＝１１５．５５
ΣΔｅ_ｉ＝６９５５＋３１６０＋４３０５×１１５．５５×０．６５＋４７２０×１１５．５５×０．３５＝５２４３５７．３
Σｖ_ｉ＝４８．４＋３６＋６４．７×１１５．５５×０．６５＋６４．４×１１５．５５×０．３５＝７５４８．５８３
ＳＰ値＝（ΣΔｅ_ｉ／Σｖ_ｉ）^１／２＝（５２４３５７．３／７５４８．５８３）^１／２＝８．３３５ Structural unit derived from (a-2)

Total number of 1,2-butylene groups and 1,4-butylene groups = (6600-85-44)/56 = 115.55
ΣΔe _i =6955+3160+4305×115.55×0.65+4720×115.55×0.35=524357.3
Σv _i =48.4+36+64.7×115.55×0.65+64.4×115.55×0.35=7548.583
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(524357.3/7548.583) ^1/2 =8.335

１，２－ブチレン基及び１，４－ブチレン基の合計個数＝（４８００－８５）／５６＝８４．２０
ΣΔｅ_ｉ＝６９５５＋４３０５×８４．２０×０．６５＋４７２０×８４．２０×０．３５＝３８１６５０．２
Σｖ_ｉ＝４８．４＋６４．７×８４．２０×０．６５＋６４．４×８４．２０×０．３５＝５４８７．０６８
ＳＰ値＝（ΣΔｅ_ｉ／Σｖ_ｉ）^１／２＝（３８１６５０．２／５４８７．０６８）^１／２＝８．３４０ Structural unit derived from (a-3)

Total number of 1,2-butylene groups and 1,4-butylene groups = (4800-85)/56 = 84.20
ΣΔe _i =6955+4305×84.20×0.65+4720×84.20×0.35=381650.2
Σv _i =48.4+64.7×84.20×0.65+64.4×84.20×0.35=5487.068
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(381650.2/5487.068) ^1/2 =8.340

Structural unit straight chain C12 derived from (d-2)
ΣΔe _i =6955+1180×11+1125=21060
Σv _i =48.4+16.1×11+33.5=259
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(21060/259) ^1/2 =9.017
Branch C12
ΣΔe _i =6955+1180×9+1125×2+820=20645
Σv _i =48.4+16.1×9+33.5×2−1.0=259.3
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(20645/259.3) ^1/2 =8.923
Linear C13
ΣΔe _i =6955+1180×12+1125=22240
Σv _i =48.4+16.1×12+33.5=275.1
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(22240/275.1) ^1/2 =8.991
Branch C13
ΣΔe _i =6955+1180×10+1125×2+820=21825
Σv _i =48.4+16.1×10+33.5×2−1.0=275.4
SP value=(ΣΔe _i /Σv _i ) ^1/2 =(21825/275.4) ^1/2 =8.902
SP value of structural unit derived from (d-2) = (9.017 × 40 + 8.923 × 10 + 8.991 × 40 + 8.902 × 10) / 100 = 8.986

<Method for measuring NOACK evaporation amount of lubricating oil composition>
It was measured according to the method of ASTM D 5800 (measurement conditions: 250°C, 1 hour).

<Method for measuring HTHS viscosity of lubricating oil composition>
It was measured at 60°C, 80°C, 100°C and 150°C according to the method of ASTM D 4683.

<Method for measuring dynamic viscosity of lubricating oil composition and method for calculating viscosity index>
Kinematic viscosities at 40° C. and 100° C. were measured by the method of JIS-2283, and the viscosity index was calculated by the method of JIS-2283. It means that the larger the value of the viscosity index, the higher the effect of improving the viscosity index.

<Rolling friction characteristics - MTM (coefficient of friction)>
Equipment: PCS Instruments MTM-2
Disc: MTM polished disc (standard) (0.01 micron)
Ball: Drilled 3/4 AISI52100 precision steel ball
Speed: 10mm/s to 3,000mm/s
Temperature: 40°C, 100°C
Sliding/rolling ratio: 50%
Load: 30N
A Stribeck curve was obtained as a result of the friction evaluation, and the friction coefficient at a speed of 100 mm/s at each temperature was used as the measurement result. If the friction coefficient at the measurement temperature of 100 ° C. is 0.055 or less and the friction coefficient at the measurement temperature of 40 ° C. is 0.060 or less, it means that the fuel consumption reduction effect is high. means high. A low coefficient of friction at each temperature means that friction loss can be reduced in that temperature range, and fuel efficiency is improved.

From the results in Tables 2 to 4, it can be seen that the lubricating oil composition of the present invention has an excellent rolling friction reducing effect at 100°C and 40°C while maintaining appropriate evaporability at 250°C.
On the other hand, it can be seen that the lubricating oil compositions of Comparative Examples 1 to 7, which fall outside the scope of the present invention, have extremely high coefficients of friction and inferior friction properties compared to the Examples. In particular, from the results of Comparative Example 3, it can be seen that when the HTHS viscosity is lowered without using the ester oil, not only the NOACK evaporation amount increases but also the rolling friction coefficient is inferior. From these results, it can be seen that the lubricating oil resin composition that satisfies the scope of the present invention is excellent in the effect of reducing rolling friction and highly effective in reducing fuel consumption.

Since the lubricating oil composition containing the viscosity index improver of the present invention has excellent frictional properties, it is expected to reduce fuel consumption. [ATF, DCTF and belt-CVTF, etc.], traction oil (toroidal-CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (construction machine hydraulic oil and industrial hydraulic oil, etc.) and engine oil (gasoline and For diesel), it can be suitably used as a lubricating oil composition for internal combustion engines, especially a lubricating oil composition for hybrid vehicles.

Claims (16)

a (co)polymer (A) having a main chain having a repeating unit derived from a polymerizable monomer and a side chain having a polyolefin structure;
an ester oil (B);
A lubricating oil composition containing a detergent and/or dispersant and an antioxidant,
The HTHS viscosity of the lubricating oil composition at 150° C. is 2.55 to 2.80 mPa s, and the HTHS viscosity of the lubricating oil composition at 100° C. is 3.0 to 5.0 mPa s. The HTHS viscosity at 80 ° C. of is 4.0 to 6.8 mPa s, the HTHS viscosity at 60 ° C. of the lubricating oil composition is 8.0 to 11.0 mPa s, and the NOACK evaporation amount of the lubricating oil composition is 15 to 25% by weight. The (co)polymer (A) contains, as constituent monomers, a monomer having a polyolefin structure having 50 to 1,000 carbon atoms at one end and a (meth)acryloyl group at the other end. A lubricating oil composition according to claim 1, which is a (co)polymer. 3. The lubricating oil composition according to claim 1, wherein the (co)polymer (A) has a weight average molecular weight of 100,000 to 1,000,000. 3. The lubricating oil composition according to claim 1, wherein the (co)polymer (A) has a solubility parameter (SP value) of 9.1 to 9.5 (cal/cm ³ ) ^1/2 . The (co)polymer (A) comprises a monomer (a) represented by the following general formula (1) and a (meth)acrylic acid alkyl ester (b) having an alkyl group having 1 to 4 carbon atoms. 3. The lubricating oil composition according to claim 1, which is a copolymer containing as a monomer.

[In general formula (1), 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 has 2 carbon atoms; is an alkylene group of ∼4, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R ² is a carbonization containing a 1,2-butylene group as a structural unit A residue obtained by removing one hydrogen atom from a hydrogen polymer; p is a number of 0 or 1; ] Based on the total weight of the monomers constituting the (co)polymer (A), the total weight ratio of the monomers (a) and (b) constituting (A) is 50 to 90% by weight. A lubricating oil composition according to claim 5 . The (co)polymer (A) contains ethyl (meth)acrylate and/or propyl (meth)acrylate and butyl (meth)acrylate as constituent monomers, and ethyl (meth)acrylate in the constituent monomers and the weight ratio (X _{2-3 /X 4 ) of the total weight (X 2-3 ) of} propyl (meth)acrylate and the weight (X ₄ ) of butyl (meth)acrylate is 0.1 or more and 1.0 or less A lubricating oil composition according to claim 5. The (co)polymer (A) contains ethyl (meth)acrylate and/or propyl (meth)acrylate as constituent monomers, and ethyl (meth)acrylate and propyl (meth)acrylate in the constituent monomers 6. The weight ratio (X _{2-3 /} X _a ) between the total weight (X _2-3 ) and the weight (X _a ) of the monomer (a) is 0.6 or more and 2.5 or less. The lubricating oil composition described. The lubricating oil composition according to claim 5, wherein the (co)polymer (A) is a copolymer containing a monomer (c) represented by the following general formula (2) as a constituent monomer.

[In the general formula (2), R ³ is a hydrogen atom or a methyl group; -X ² - is a group represented by ^-O- or -NH-; R ⁴ is an alkylene group having 2 to 4 carbon atoms; an alkyl group having a number of 1 to 8; q is an integer of 1 to 20, and when q is 2 or more, R ⁵ may be the same or different; ] The (co)polymer (A) is a copolymer containing as a constituent monomer a (meth)acryloyl monomer (d) having a linear or branched alkyl group having 9 to 36 carbon atoms. A lubricating oil composition according to claim 5. 3. The lubricating oil composition according to claim 1, containing 0.1 to 10% by weight of the (co)polymer (A). 3. The lubricating oil composition according to claim 1, wherein the ester oil (B) has a kinematic viscosity at 100° C. of 2.0 to 4.0 mm ² /s. 3. The lubricating oil composition according to claim 1, wherein the ester oil (B) is bis(2-ethylhexyl) adipate and/or bis(2-ethylhexyl) sebacate. Claim 1 or 2, further comprising at least one additive selected from the group consisting of oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors and pour point depressants. The lubricating oil composition described. 3. The lubricating oil composition according to claim 1, wherein the lubricating oil composition has a viscosity index of 280 or more. 3. The lubricating oil composition according to claim 1, which is for internal combustion engines.

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