Viscosity index improver composition and lubricating oil composition

Abstract

The purpose of the present invention is to provide a viscosity index improver composition that does not readily produce a gel. The present invention pertains to a viscosity index improver composition and the like, the viscosity index improver composition containing: a copolymer (A) containing, as essential constituent monomers, a polyolefin monomer (a) represented by general formula (1) and an alkyl (meth) acrylate (b) having a C1-4 alkyl group, and a Fischer-Tropsch-derived base oil (B) having a kinematic viscosity at 100 DEG C of 4.0 mm2 / s or less, the content of the monomer (a) is 1-20 wt% and the content of the alkyl (meth) acrylate (b) is 45-85 wt%, based on the total weight of the monomers constituting the copolymer (A). # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a viscosity index improver composition and a lubricating oil composition. Background Art

[0002] In recent years, in order to achieve the reduction of CO2 emissions and the protection of oil resources, there is a further demand for automobiles to be more fuel-efficient. As one of the measures to save fuel, the low viscosity of engine oil can be cited. However, if the viscosity is too low, especially on the high-temperature side, problems such as leakage and burning of bearings will occur. In response to this problem, the U.S. SAE's engine oil viscosity standard (SAEJ300) stipulates a minimum guaranteed viscosity. In the 0W-20 grade, as the viscosity under high temperature and high shear (HTHS viscosity), the 150°C HTHS viscosity (ASTM D4683 or D5481) is stipulated to be 2.6 mPa·s or more, and in the 0W-16 grade it is stipulated to be 2.3 mPa·s or more.

[0003] In addition, in recent years, hybrid vehicles and plug-in hybrid vehicles that combine electricity and gasoline have also been fuel-efficient based on hardware. Such hybrid vehicles are different from existing gasoline vehicles in that the temperature of the engine oil during driving is low. Specifically, in the case of gasoline vehicles, the temperature is usually 80 to 100°C during driving, while in hybrid vehicles, it is 40 to 80°C. Therefore, for engine oils used in hybrid vehicles, etc., there is a further requirement for low viscosity in the 40 to 80°C region. Therefore, a method of adding a viscosity index improver to the lubricating oil to improve the temperature dependence of viscosity is widely used. As viscosity index improvers, methacrylate copolymers (Patent Documents 1 to 3) and comb-type copolymers (Patent Documents 4 to 6) are used. In particular, comb-type copolymers are known to be highly effective in improving the temperature dependence of viscosity.

[0004] From the viewpoint of handling, viscosity index improvers are generally distributed in the form of viscosity index improver compositions containing a high concentration of a copolymer in a base oil. However, viscosity index improver compositions containing a high concentration of a comb-type copolymer have a problem of generating gels when exposed to high temperatures in summer or low temperatures in winter or in cold regions.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 2732187

[0008] Patent Document 2: Japanese Patent No. 2754343

[0009] Patent Document 3: Japanese Patent No. 3831203

[0010] Patent Document 4: Japanese Patent No. 3474918

[0011] Patent Document 5: Japanese Patent Application No. 2008-546894

[0012] Patent Document 6: Japanese Patent Application No. 2010-532805 Summary of the invention

[0013] Problems to be solved by the invention

[0014] An object of the present invention is to provide a viscosity index improver composition that is less likely to produce gel.

[0015] Means for solving problems

[0016] The present inventors have conducted intensive studies and, as a result, have accomplished the present invention.

[0017] That is, the present invention relates to: a viscosity index improver composition comprising a copolymer (A) and a 100° C. kinematic viscosity of 4.0 mm 2 / s or less, the copolymer (A) comprising a polyolefin monomer (a) represented by the following general formula (1) and an alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms (b) as essential constituent monomers, wherein the content of the monomer (a) is 1 to 20% by weight and the content of the alkyl (meth)acrylate (b) is 45 to 85% by weight based on the total weight of the monomers constituting the copolymer (A); and a lubricating oil composition comprising the viscosity index improver composition and at least one additive selected from the group consisting of a detergent, a dispersant, an antioxidant, an oiliness improver, a pour point depressant, a friction and wear modifier, an extreme pressure agent, a defoamer, an anti-emulsifier, a metal deactivator and a corrosion inhibitor.

[0018] [Chemistry 1]

[0019]

[0020] [In the general formula (1), R 1 is a hydrogen atom or a methyl group; -X 1 - is -O-, -O(AO) m - or -NH-, A is an alkylene group having 2 to 4 carbon atoms, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R 2 It is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit; p is a number of 0 or 1.]

[0021] Effects of the Invention

[0022] The viscosity index improver composition of the present invention exhibits an effect of preventing gel from being generated. DETAILED DESCRIPTION

[0023] The viscosity index improver composition of the present invention comprises a copolymer (A) and a 100° C. kinematic viscosity of 4.0 mm 2 / s or less, the copolymer (A) comprising a polyolefin monomer (a) represented by the following general formula (1) and an alkyl (meth)acrylate (b) having an alkyl group with 1 to 4 carbon atoms as essential constituent monomers, wherein the content of the monomer (a) is 1 to 20% by weight and the content of the alkyl (meth)acrylate (b) is 45 to 85% by weight, based on the total weight of the monomers constituting the copolymer (A).

[0024] [Chemistry 2]

[0025]

[0026] [In the general formula (1), R 1 is a hydrogen atom or a methyl group; -X 1 - is -O-, -O(AO) m - or -NH-, A is an alkylene group having 2 to 4 carbon atoms, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R 2 It is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit; p is a number of 0 or 1.]

[0027] <Copolymer (A)>

[0028] The copolymer (A) in the present invention contains the polyolefin monomer (a) represented by the above general formula (1) and the (meth)acrylic acid alkyl ester (b) having an alkyl group having 1 to 4 carbon atoms as essential constituent monomers.

[0029] The polyolefin monomer (a) in the present invention is a monomer obtained by modifying a hydrocarbon polymer described below and reacting the modified hydrocarbon polymer with (meth)acrylic acid. In addition, "(meth)acrylic acid" means methacrylic acid or acrylic acid.

[0030] R in the general formula (1) 1 It is a hydrogen atom or a methyl group. Among these, a methyl group is preferred from the viewpoint of the viscosity index improvement effect.

[0031] -X in the general formula (1) 1 - is -O-, -O(AO) m - or -NH-.

[0032] A is an alkylene group having 2 to 4 carbon atoms.

[0033] Examples of the alkylene group having 2 to 4 carbon atoms include ethylene, 1,2-propylene or 1,3-propylene, and 1,2-butylene, 1,3-butylene or 1,4-butylene.

[0034] m is an integer of 1 to 10, and is preferably an integer of 1 to 4, and more preferably an integer of 1 to 2, from the viewpoint of HTHS viscosity in the effective temperature range (80 to 150° C.).

[0035] When m is 2 or more, A may be the same or different, (AO) m The parts may be randomly bonded or block bonded.

[0036] -X 1 -, from the viewpoint of HTHS viscosity in the effective temperature range (80 to 150°C), -O- and -O(AO) are preferred. m The group represented by - is more preferably a group represented by -O- and -O(CH2CH2O)-.

[0037] p is a number of 0 or 1.

[0038] R in the general formula (1) 2 It is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group (-CH2CH(CH2CH3)- or -CH(CH2CH3)CH2-) as a structural unit.

[0039] Examples of the hydrocarbon polymer containing a 1,2-butylene group as a structural unit include a polymer containing 1-butene as a constituent monomer and a polymer obtained by hydrogenating the terminal double bond of a 1,2-adduct obtained by polymerizing 1,3-butadiene.

[0040] The hydrocarbon polymer may be a block polymer or a random polymer.

[0041] The hydrocarbon polymer including a 1,2-butylene group as a structural unit may be a hydrocarbon polymer further including a structural unit other than the 1,2-butylene group.

[0042] Examples of the monomers constituting the hydrocarbon polymer include (1) aliphatic unsaturated hydrocarbons, (2) alicyclic unsaturated hydrocarbons, and (3) aromatic group-containing unsaturated hydrocarbons. When the hydrocarbon polymer has double bonds, part or all of the double bonds may be hydrogenated by hydrogenation.

[0043] Examples of the monomers constituting the hydrocarbon polymer include:

[0044] (1) Aliphatic unsaturated hydrocarbons [olefins with 2 to 36 carbon atoms (such as ethylene, propylene, isobutene, 1-butene, 2-butene, pentene, heptene, diisobutene, octene, dodecene, octadecene, tricosene, hexacosene, etc.), dienes with 2 to 36 carbon atoms (such as 1,2-butadiene, 1,3-butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.)]

[0045] (2) Alicyclic unsaturated hydrocarbons [such as cyclohexene, (di)cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, ethylidenebicycloheptene, etc.]

[0046] (3) Unsaturated hydrocarbons containing aromatic groups (such as styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, vinylnaphthalene, divinylbenzene, divinyltoluene, divinyldimethylbenzene, trivinylbenzene, etc.) etc.

[0047] The hydrocarbon polymers composed of them can be block polymers or random polymers. In addition, when the hydrocarbon polymer has double bonds, a part or all of the double bonds can be hydrogenated by hydrogenation. In one embodiment, the hydrocarbon polymer in R 2 can be a hydrocarbon polymer using only monomers with 4 carbon atoms as the constituent monomers, and the monomers with 4 carbon atoms can be at least one selected from the group consisting of 1-butene and 1,3-butadiene, or a combination of isobutene and at least one selected from the group consisting of 1-butene and 1,3-butadiene.

[0048] The number average molecular weight (hereinafter simply referred to as Mn) of monomer (a) is preferably 800 to 10,000, more preferably 1,000 to 9,500, further preferably 1,200 to 9,000, and particularly preferably 2,000 to 8,700. If the Mn of monomer (a) is 800 or more, it has a tendency to have good solubility in the Fischer-Tropsch derived base oil (B), and if it is 10,000 or less, it has a tendency to have good copolymerizability with other monomers.

[0049] In the present invention, the weight average molecular weight (hereinafter simply referred to as Mw) and Mn can be measured by gel permeation chromatography (hereinafter simply referred to as GPC) under the following conditions.

[0050] <Measurement conditions of Mw and Mn>

[0051] Apparatus: "HLC-8320GPC" [manufactured by Tosoh Corporation]

[0052] Column: "TSKgel GMHXL" [manufactured by Tosoh Corporation] 2 columns

[0053] "TSKgel Multipore H XL -M"1 root

[0054] Measurement temperature: 40℃

[0055] Sample solution: 0.25 wt% tetrahydrofuran solution

[0056] Solution injection volume: 10.0μl

[0057] Detection device: Refractive index detector

[0058] Reference material: Standard polystyrene (TS Reference material: Standard polystyrene (TSKstandardPOLYSTYRENE))

[0059] 12 types (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]

[0060] The monomer (a) can be obtained by 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. Alternatively, it can be obtained by an ester exchange reaction between a polymer (Y) containing a hydroxyl group at one end and an alkyl (meth)acrylate (preferably having 1 to 4 carbon atoms) such as methyl (meth)acrylate.

[0061] Specific examples of the polymer (Y) having a hydroxyl group at one end include the following (Y1) to (Y4).

[0062] Alkylene oxide adduct (Y1): a compound obtained by polymerizing an unsaturated hydrocarbon (x) in the presence of an ionic polymerization catalyst (such as a sodium catalyst) to obtain a hydrocarbon polymer and adding an alkylene oxide (such as ethylene oxide and propylene oxide) to the hydrocarbon polymer (in this case, the monomer (a) is -X in the general formula (1) 1 -for-(AO) m -, p=0).

[0063] Borohydride (Y2): a hydroboration reaction product of a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end (e.g., a compound described in U.S. Patent No. 4,316,973) (in this case, monomer (a) is -X in the general formula (1) 1 - is -O-, p=0).

[0064] Maleic anhydride-ene-amino alcohol adduct (Y3): a compound obtained by imidizing a reaction product obtained by reacting a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end with an ene of maleic anhydride with an amino alcohol (in this case, the monomer (a) is -X in the general formula (1) 1 - is -O-, p=1).

[0065] Hydroformylation-hydrogenation product (Y4): a compound obtained by hydroformylating a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end and then subjecting it to a hydrogenation reaction (e.g., a compound described in Japanese Unexamined Patent Publication No. 63-175096) (in this case, monomer (a) is -X in the general formula (1) 1 - is -O-, p=0).

[0066] Among these polymers (Y) containing a hydroxyl group at one end, the alkylene oxide adduct (Y1) and the borohydride (Y2) are preferred from the viewpoint of the viscosity index improvement effect, and the alkylene oxide adduct (Y1) is more preferred.

[0067] From the viewpoint of the viscosity index improvement effect, R in the general formula (1) is 2 The proportion of butadiene in all monomers (the weight proportion of 1,3-butadiene in all constituent monomers in a hydrocarbon polymer containing 1,2-butylene groups as structural units) is preferably 50% by weight or more, more preferably 75% by weight or more, further preferably 85% by weight or more, and particularly preferably 90% by weight or more.

[0068] The hydrocarbon polymer containing a 1,2-butylene group as a structural unit in the general formula (1) may have an isobutylene group from the viewpoint of the effect of improving the viscosity index.

[0069] From the viewpoint of the viscosity index improving effect, the total amount of isobutylene groups and 1,2-butylene groups is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more based on the total number of moles of monomers constituting the hydrocarbon polymer.

[0070] As a method for increasing the ratio of the total amount of isobutylene groups and 1,2-butylene groups in a hydrocarbon polymer, for example, the following method can be adopted. In the case of the above-mentioned alkylene oxide adduct (Y1), for example, in anionic polymerization using 1,3-butadiene, by lowering the reaction temperature {for example, the boiling point of 1,3-butadiene (-4.4°C) or less} and reducing the amount of polymerization initiator added 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-mentioned borohydride (Y2), maleic anhydride-ene-amino alcohol adduct (Y3) and hydroformylation-hydride (Y4), the above ratio can be increased by increasing the degree of polymerization of the hydrocarbon polymer having a double bond at one end.

[0071] Regarding the structure derived from 1-butene and / or 1,3-butadiene of the hydrocarbon polymer in the general formula (1), from the perspective of the viscosity index improvement effect and copolymerizability with other monomers, the proportion of 1,2-butylene groups (number of moles of 1,2-butylene groups / total number of moles of constituent monomers×100) is preferably 30 mol% or more, more preferably 30 to 70 mol%, based on the total number of moles of the constituent monomers of the hydrocarbon polymer.

[0072] The proportion of 1,2-butylene can be determined by 13 Specifically, for example, when only monomers with 4 carbon atoms are used as monomers, the 13 The hydrocarbon polymer was analyzed by C-NMR, and the mole % of 1,2-butylene groups was calculated and determined based on the total mole number of the structural units of the hydrocarbon polymer using the following mathematical formula (1). 13 In C-NMR, the peak of the tertiary carbon atom (-CH2CH(CH2CH3)-) derived from the 1,2-butylene group appears at an integral value (integral value B) of 26 to 27 ppm. The proportion of the 1,2-butylene group can be determined from the integral value of the peak and the integral value of the peak of the total carbon of the hydrocarbon polymer (integral value C).

[0073] Ratio of 1,2-butylene group (mol%) = {(integral value B) × 4} / (integral value C) × 100 (1)

[0074] It should be noted that in order to increase the proportion of 1,2-butylene groups, for example, in anionic polymerization using 1,3-butadiene, the reaction temperature is set below the boiling point of 1,3-butadiene (-4.4°C) and the amount of polymerization initiator added is reduced relative to 1,3-butadiene; in order to reduce the proportion of 1,2-butylene groups, the reaction temperature is set above the boiling point of 1,3-butadiene and the amount of initiator is increased.

[0075] The total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer containing 1,2-butylene groups as structural units in the general formula (1) can be expressed by 13 Specifically, for example, when only monomers with 4 carbon atoms are used as monomers, the 13 The hydrocarbon polymer was analyzed by C-NMR, and the total molar % of the isobutylene group and the 1,2-butylene group was determined based on the total molar number of the structural units of the hydrocarbon polymer by calculation using the following mathematical formula (2). 13 In C-NMR, the peak of the methyl group derived from the isobutylene group appears at an integral value of 30 to 32 ppm (integral value A), and the peak of the branched methylene group (-CH2CH(CH2CH3)- or -CH(CH2CH3)CH2-) derived from the 1,2-butylene group appears at an integral value of 26 to 27 ppm (integral value B). The total molar % of the isobutylene group and the 1,2-butylene group based on the total molar number of the structural units of the hydrocarbon polymer can be determined from the integral value of the above peaks and the integral value of the peak of the total carbon of the hydrocarbon polymer (integral value C).

[0076] Total amount of isobutylene group and 1,2-butylene group (mol%) = 100 × {(integral value A) × 2 + (integral value B) × 4} / (integral value C) (2)

[0077] In R 2 When the hydrocarbon polymer in the general formula (1) contains butadiene or butadiene and 1-butene as the constituent monomers, from the viewpoint of the viscosity index improvement effect and copolymerizability with other monomers, some or all of R 2 In the structure derived from butadiene or from butadiene and 1-butene, the molar ratio of 1,2-adduct to 1,4-adduct (1,2-adduct / 1,4-adduct) is preferably 5 / 95 to 95 / 5, more preferably 20 / 80 to 80 / 20, and further preferably 30 / 70 to 70 / 30.

[0078] In R 2 When the constituent monomers of the hydrocarbon polymer in the formula (1) include 1,3-butadiene, or include 1,3-butadiene and 1-butene, a part or all of R 2 The molar ratio of the 1,2-adduct from 1,3-butadiene or the 1,4-adduct from the structure of 1,3-butadiene and 1-butene can be determined by 1 H-NMR, 13 C-NMR, Raman spectroscopy, etc.

[0079] From the viewpoint of making the SP value of the copolymer (A) moderate and the solubility in the Fischer-Tropsch derived base oil (B), the solubility parameter (hereinafter referred to as SP value) of the structural unit derived from the monomer (a) (the structure in which the (meth)acryloyl group of the monomer (a) reacts to form a single bond) is preferably 7.0 to 9.0 (cal / cm 3 ) 1 / 2 , more preferably 7.3 to 8.5 (cal / cm 3 ) 1 / 2 .

[0080] Regarding the SP value, for example, if R 2 The SP value tends to decrease when the degree of branching is large and the number of carbon atoms is large, and the SP value tends to increase when the degree of branching is small and the number of carbon atoms is small.

[0081] It should be noted that the SP value in the present invention refers to the value recorded in page 152 (Table.5) of the Fedors method (Polymer Engineering and Science, February, 1974, Vol. 14, No. 2, P147-154) (heat of vaporization and molar volume of an atom or functional group at 25°C), and the value calculated by the mathematical formula (28) on page 153. Specifically, it can be calculated based on the Δe recorded in the following Table 1 as a parameter of the Fedors method. i and v i The numerical value of is calculated by substituting the numerical value corresponding to the types of atoms and atomic groups in the molecular structure into the following mathematical formula.

[0082] SP value = (ΣΔe i / Σv i ) 1 / 2

[0083] [Table 1]

[0084] Parameters of Fedors Method

[0085] Atom or group of atoms <![CDATA[Δe i [cal / mol]]]> <![CDATA[v i [cm 3 / mol]]]> <![CDATA[CH3]]> 1125 33.5 <![CDATA[CH2]]> 1180 16.1 CH 820 -1.0 C 350 -19.2 <![CDATA[H2C=]]> 1030 28.5 -CH= 1030 13.5 C＝ 1030 -5.5 HC≡ 920 27.4 -C≡ 1690 6.5 Phenyl 7630 71.4 Phenylene (o, m, p) 7630 52.4 Phenyl (trisubstituted) 7630 33.4 Phenyl (tetrasubstituted) 7630 14.4 Phenyl(pentasubstituted) 7630 -4.6 Phenyl(hexasubstituted) 7630 -23.6 Ring closed with 5 or more atoms 250 16 Ring closed with 3 or 4 atoms 750 18 <![CDATA[CO3 (Carbonate)]]> 4200 22.0 COOH 6600 28.5 <![CDATA[CO2]]> 4300 18.0 CO 4150 10.8 CHO (aldehyde) 5100 22.3 <![CDATA[CO2CO2 (oxalate)]]> 6400 37.3 <![CDATA[C2O3 (anhydrous)]]> 7300 30.0 HCOO (Formate) 4300 32.5 <![CDATA[CONH2]]> 10000 17.5 CONH 8000 9.5 CON 7050 -7.7 HCON 6600 11.3 HCONH 10500 27.0 COCl 5000 38.0 <![CDATA[NH2]]> 3000 19.2 NH 2000 4.5 N 1000 -9.0 -N＝ 2800 5.0 CN 6100 24.0 <![CDATA[NO2 (aliphatic)]]> 7000 24.0 <![CDATA[NO2 (aromatic)]]> 3670 32.0 <![CDATA[NO3]]> 5000 33.5 <![CDATA[NO2 (Nitrite)]]> 2800 33.5 CSN 4800 37.0 NCO 6800 35.0 <![CDATA[NF z ]]> 1830 33.1 <![CDATA[NF2]]> 1210 24.5 O 800 3.8 OH 7120 10.0 OH (disubstituted or on adjacent carbon atoms) 5220 13.0

[0086] The SP value of the structural unit derived from the monomer (a) can be calculated using the above parameters based on the molecular structure of the structural unit derived from the monomer (a), and can be adjusted to a desired range by appropriately adjusting the weight fraction of the monomer (unsaturated hydrocarbon (x)) used.

[0087] In addition, when the copolymer (A) uses two or more monomers (a) in combination, the SP values ​​of the various structural units constituting the monomer (a) are calculated by the above method, and the value obtained by arithmetically averaging the SP values ​​of the structural units from each monomer (a) based on the weight fraction of the constituent monomer units preferably satisfies the above range of the SP values ​​of the structural units from the monomer (a).

[0088] Examples of the (meth)acrylic acid alkyl ester (b) having an alkyl group having 1 to 4 carbon atoms (hereinafter sometimes referred to as monomer (b)) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, 1-methylpropyl (meth)acrylate, 2-methylpropyl (meth)acrylate, and 1,1-dimethylethyl (meth)acrylate.

[0089] Among these, from the viewpoint of the effect of improving the viscosity index, ethyl (meth)acrylate, n-butyl (meth)acrylate and isobutyl (meth)acrylate are preferred, ethyl (meth)acrylate and n-butyl (meth)acrylate are more preferred, and n-butyl (meth)acrylate is particularly preferred.

[0090] In the present invention, the copolymer (A) may contain a (meth)acryloyl monomer (c) having an alkyl group having 9 to 36 carbon atoms and / or a monomer (d) represented by the following general formula (2) as constituent monomers.

[0091] [Chemistry 3]

[0092]

[0093] [In 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; R 5 is an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 20 carbon atoms; q is an integer of 1 to 20, and when q is 2 or more, R 4 Can be the same or different.]

[0094] Examples of the (meth)acryloyl monomer (c) having an alkyl group with 9 to 36 carbon atoms include (meth)acrylic acid alkyl esters having a linear alkyl group {e.g., n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, n-eicosyl (meth)acrylate, n-docosyl (meth)acrylate, n-tetracosyl (meth)acrylate, n-triacontyl (meth)acrylate, and n-hexadecyl (meth)acrylate} esters, etc.}, (meth)acrylamide having a straight-chain alkyl group {for example, N-nonyl (meth)acrylamide, N-decyl (meth)acrylamide, N-dodecyl (meth)acrylamide, N-tridecyl (meth)acrylamide, N-tetradecyl (meth)acrylamide, N-pentadecyl (meth)acrylamide, N-hexadecyl (meth)acrylamide, etc.}, alkyl (meth)acrylate having a branched alkyl group {for example, 2-methylundecyl (meth)acrylate, isododecyl (meth)acrylate, 2-methyldodecyl (meth)acrylate, isotridecyl (meth)acrylate, 2-methyltridecyl (meth)acrylate, isotetradecyl (meth)acrylate, 2-methyl -methyltetradecyl (meth)acrylate, isopentadecyl (meth)acrylate, 2-methylpentadecyl (meth)acrylate, isohexadecyl (meth)acrylate, 2-octyldecyl (meth)acrylate, ester of ethylene glycol mono-2-octylpentadecyl ether and (meth)acrylic acid, 2-n-octyldodecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, 2-n-dodecylhexadecyl (meth)acrylate, 2-n-tetradecyloctadecyl (meth)acrylate, 2-n-dodecylpentadecyl (meth)acrylate, 2-n-tetradecylheptadecyl (meth)acrylate, 2-n-hexadecylheptadecyl (meth)acrylate, 2-n-hexadecyltadecyl (meth)acrylate alkyl esters, 2-n-hexadecylbehenyl (meth)acrylate, 2-n-eicosylbehenyl (meth)acrylate, 2-n-tetracosylhexacosyl (meth)acrylate, etc., (meth)acrylamide having a branched alkyl group {for example, N-2-methylundecyl (meth)acrylamide, N-isododecyl (meth)acrylamide, N-2-methyldodecyl (meth)acrylamide, N-isotridecyl (meth)acrylamide, N-2-methyltridecyl (meth)acrylamide, N-isotetradecyl (meth)acrylamide, N-2-methyltetradecyl (meth)acrylamide, N-isopentadecyl (meth)acrylamide, N-2-methylpentadecyl (meth)acrylamide,N-isohexadecyl (meth) acrylamide, etc., esters of (meth) acrylic acid and 1 to 20 mol of alkylene oxide (2 to 4 carbon atoms) adducts of alkyl alcohols having 9 to 36 carbon atoms.

[0095] As the monomer (c), linear alkyl (meth)acrylates (alkyl (meth)acrylates having a linear alkyl group) and branched alkyl (meth)acrylates (alkyl (meth)acrylates having a branched alkyl group) are preferred from the viewpoint of the viscosity index improving effect.

[0096] As the monomer (c), (meth)acrylates of mixtures of alkyl alcohols such as Neodol (registered trademark) 23 (a mixture of linear and branched alkyl alcohols having 12 to 13 carbon atoms, manufactured by Shell), Neodol (registered trademark) 45 (a mixture of linear and branched alkyl alcohols having 14 to 15 carbon atoms, manufactured by Shell) can be used.

[0097] R in the general formula (2) 3 It is a hydrogen atom or a methyl group. Among these, a methyl group is preferred from the viewpoint of the viscosity index improvement effect and the HTHS viscosity reduction at 100°C.

[0098] -X in the general formula (2) 2 - is a group represented by -O- or -NH-. Among these, a group represented by -O- is preferred from the viewpoint of the viscosity index improvement effect and the HTHS viscosity reduction at 100°C.

[0099] R in the general formula (2) 4 It is an alkylene group having 2 to 4 carbon atoms.

[0100] Examples of the alkylene group having 2 to 4 carbon atoms include ethylene, isopropylene, 1,2-propylene or 1,3-propylene, isobutylene, and 1,2-butylene, 1,3-butylene or 1,4-butylene.

[0101] R 4 O is an alkyleneoxy group having 2 to 4 carbon atoms, and examples thereof include ethyleneoxy, 1,2-propyleneoxy or 1,3-propyleneoxy, 1,2-butyleneoxy, 1,3-butyleneoxy or 1,4-butyleneoxy.

[0102] q in the general formula (2) is an integer of 1 to 20, and is preferably an integer of 1 to 5, and more preferably an integer of 1 to 2, from the viewpoint of reducing the HTHS viscosity at 100°C.

[0103] When q is 2 or more, R 4 O can be the same or different, (R 4 O) qThe bonding form of the parts may be random or block-like.

[0104] R in the general formula (2) 5 is an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 20 carbon atoms. 5 Examples include alkyl groups having 1 to 4 carbon atoms (straight-chain or branched alkyl groups having 1 to 4 carbon atoms) {e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, etc.}, alkyl groups having 5 to 18 carbon atoms {e.g., pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, etc.}, aryl groups having 6 to 20 carbon atoms {e.g., phenyl, benzyl, phenethyl, tolyl, naphthyl, naphthylmethyl, anthracenyl, phenanthrenyl, fluorenyl, etc.}, and the like.

[0105] Among these, from the viewpoint of reducing the HTHS viscosity at 100° C., a linear alkyl group having 1 to 4 carbon atoms is preferred, and a linear alkyl group having 4 carbon atoms (n-butyl group) is more preferred.

[0106] Specific examples of the monomer (d) include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate {e.g., 2-(n-butoxy)ethyl (meth)acrylate, 2-(tert-butoxy)ethyl (meth)acrylate, 2-(sec-butoxy)ethyl (meth)acrylate, 2-(isobutoxy)ethyl (meth)acrylate, etc.}, phenoxyethyl (meth)acrylate, benzyloxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, propoxypropyl (meth)acrylate, butoxypropyl (meth)acrylate {e.g., 2-(n-butoxy)propyl (meth)acrylate, -2-(tert-butoxy)propyl (meth)acrylate, 2-(sec-butoxy)propyl (meth)acrylate, 2-(isobutoxy)propyl (meth)acrylate, etc.}, phenoxypropyl (meth)acrylate, benzyloxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, propoxybutyl (meth)acrylate, butoxybutyl (meth)acrylate, phenoxybutyl (meth)acrylate, benzyloxybutyl (meth)acrylate, and esters of (meth)acrylic acid with 2 to 20 mol of at least one selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide added to a linear or branched alkyl alcohol having 1 to 18 carbon atoms or an aromatic compound having a hydroxyl group (for example, phenol, benzyl alcohol, etc.).

[0107] Among the monomers (d), ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate are preferred, and n-butoxyethyl (meth)acrylate is more preferred, from the viewpoint of the viscosity index improvement effect and the reduction in HTHS viscosity at 100°C.

[0108] The copolymer (A) in the present invention may further contain other monomers other than the monomers (a) to (d), such as a nitrogen atom-containing monomer (e), a hydroxyl group-containing monomer (f), a phosphorus atom-containing monomer (g), an aromatic ring-containing vinyl monomer (h), and other monomers (i) to (m) as constituent monomers.

[0109] The monomers (e) to (m) may be used alone or in combination of two or more.

[0110] Examples of the nitrogen atom-containing monomer (e) include the following monomers (e1) to (e4) other than the monomers (a) to (d).

[0111] Monomer containing an amide group (e1):

[0112] Examples include (meth)acrylamide, N-(N'-monoalkylaminoalkyl) (meth)acrylamide [monomers having an aminoalkyl group (having 2 to 6 carbon atoms) in which one alkyl group having 1 to 4 carbon atoms is bonded to a nitrogen atom; for example, N-(N'-methylaminoethyl) (meth)acrylamide, N-(N'-ethylaminoethyl) (meth)acrylamide, N-(N'-isopropylamino-n-butyl) (meth)acrylamide, and N-(N'-n- or isobutylamino-n-butyl) (meth)acrylamide, etc.], and dialkyl (meth)acrylamide [(meth)acrylamide 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, amine and N,N-di-n-butyl(meth)acrylamide, etc.], N-(N',N'-dialkylaminoalkyl)(meth)acrylamide [(meth)acrylamide having an aminoalkyl group (having 2 to 6 carbon atoms) in which two alkyl groups having 1 to 4 carbon atoms are bonded to the nitrogen atom of the aminoalkyl group; for example, N-(N',N'-dimethylaminoethyl)(meth)acrylamide, N-(N',N'-diethylaminoethyl)(meth)acrylamide, N-(N',N'-dimethylaminopropyl)(meth)acrylamide and N-(N',N'-di-n-butylaminobutyl)(meth)acrylamide, etc.]; N-vinylcarboxylic acid amides [N-vinylformamide, N-vinylacetamide, N-vinyl-n-propionamide or N-vinylisopropionamide, and N-vinylhydroxyacetamide, etc.], etc.

[0113] Monomers containing nitro groups (e2):

[0114] Examples thereof include 4-nitrostyrene.

[0115] Monomers containing primary to tertiary amino groups (e3):

[0116] Examples include monomers containing primary amino groups {alkenylamines having 3 to 6 carbon atoms [(meth)allylamine and crotylamine, etc.], aminoalkyl(meth)acrylates (having 2 to 6 carbon atoms) [aminoethyl(meth)acrylate, etc.]}; monomers containing secondary amino groups {monoalkylaminoalkyl(meth)acrylates [(meth)acrylates having aminoalkyl(2 to 6 carbon atoms) groups with one alkyl group having 1 to 6 carbon atoms bonded to a nitrogen atom; for example, N-tert-butylaminoethyl(meth)acrylate and N-methylaminoethyl(meth)acrylate, etc.], dienylamines having 6 to 12 carbon atoms [dimethylallylamine, etc.]}; monomers containing tertiary amino groups {dialkylaminoalkyl(meth)acrylates [having two alkyl groups having two carbon atoms bonded to a nitrogen atom; for example, N-tert-butylaminoethyl(meth)acrylate and N-methylaminoethyl(meth)acrylate, etc.]; (Meth)acrylates of aminoalkyl (carbon number 2 to 6) formed by an alkyl group having 1 to 6 atoms; for example, N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate, etc.], alicyclic (meth)acrylates having nitrogen atoms [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 their hydrochlorides, sulfates, phosphates or lower alkyl (carbon number 1 to 8) monocarboxylic acid (acetic acid, propionic acid, etc.) salts, etc.

[0117] Monomer containing nitrile group (e4):

[0118] (Meth)acrylonitrile and the like are mentioned.

[0119] Among monomers (e), (e1) and (e3) are preferred, and N-(N',N'-diphenylaminoethyl)(methyl)acrylamide, N-(N',N'-dimethylaminoethyl)(methyl)acrylamide, N-(N',N'-diethylaminoethyl)(methyl)acrylamide, N-(N',N'-dimethylaminopropyl)(methyl)acrylamide, N,N-dimethylaminoethyl(methyl)acrylate and N,N-diethylaminoethyl(methyl)acrylate are more preferred.

[0120] Hydroxyl-containing monomer (f):

[0121] Examples include aromatic monomers containing a hydroxyl group (p-hydroxystyrene, etc.), hydroxyalkyl (meth)acrylates (having 2 to 6 carbon atoms) [2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, etc.], monohydroxyalkyl or bishydroxyalkyl (having 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, olefin alcohols having 3 to 12 carbon atoms [(meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1-undecenol, etc.], olefin monools or olefin diols having 4 to 12 carbon atoms [1-butene-3-ol, 2-butene-1-ol and 2-butene-1,4-diol, etc.], hydroxyalkyl (1 to 6 carbon atoms) alkenyl (3 to 10 carbon atoms) ethers (2-hydroxyethyl propenyl ether, etc.), poly(3 alkylene glycol (the number of carbon atoms is 2 to 4 and the degree of polymerization is 2 to 50), polyoxyalkylene polyol [polyoxyalkylene ether of the above 3 to 8 valent alcohols (the number of carbon atoms of the alkylene group is 2 to 4 and the degree of polymerization is 2 to 100)], polyoxyalkylene glycol or polyoxyalkylene polyol Mono(meth)acrylates of alkyl (carbon number 1 to 4) ethers [polyethylene glycol (Mn: 100 to 300) mono(meth)acrylate, polypropylene glycol (Mn: 130 to 500) mono(meth)acrylate, methoxypolyethylene glycol (Mn: 110 to 310) (meth)acrylate, lauryl alcohol ethylene oxide adduct (2 to 30 mol) (meth)acrylate, and polyoxyethylene mono(meth)acrylate (Mn: 150 to 230) sorbitan ester, etc.], etc.

[0122] Examples of the phosphorus atom-containing monomer (g) include the following monomers (g1) to (g2).

[0123] Monomer containing phosphate group (g1):

[0124] Examples include (meth)acryloyloxyalkyl (carbon number 2 to 4) phosphates [(meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate] and alkenyl phosphates [vinyl phosphate, allyl phosphate, propylene phosphate, isopropylene phosphate, butyl phosphate, pentyl phosphate, octenyl phosphate, decenyl phosphate, and dodecenyl phosphate, etc.]. It should be noted that "(meth)acryloyloxy" means an acryloyloxy group or a methacryloyloxy group.

[0125] Monomer containing a phosphonyl group (g2):

[0126] Examples thereof include (meth)acryloyloxyalkyl (carbon number 2-4)phosphonic acid [such as (meth)acryloyloxyethylphosphonic acid] and alkenyl (carbon number 2-12)phosphonic acid [such as vinylphosphonic acid, allylphosphonic acid and octenylphosphonic acid].

[0127] Among the monomers (g), (g1) is preferred, (meth)acryloyloxyalkyl (carbon number 2 to 4) phosphate is more preferred, and (meth)acryloyloxyethyl phosphate is particularly preferred.

[0128] Vinyl monomers containing aromatic rings (h):

[0129] Examples thereof include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-crotylbenzene, indene, and 2-vinylnaphthalene.

[0130] Among the monomers (h), styrene and α-methylstyrene are preferred, and styrene is more preferred.

[0131] Monomer (i) having two or more unsaturated groups (sometimes simply referred to as monomer (i)):

[0132] Examples thereof include divinylbenzene, dienes having 4 to 12 carbon atoms (such as butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene and 1,7-octadiene), (di)cyclopentadiene, vinylcyclohexene and ethylidene bicycloheptene, limonene, ethylene di(meth)acrylate, polyoxyalkylene glycol di(meth)acrylate, pentaerythritol triallyl ether, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, esters of unsaturated carboxylic acids and diols having an Mn of 500 or more as described in International Publication No. WO01 / 009242, and esters of unsaturated alcohols and carboxylic acids.

[0133] Vinyl esters, vinyl ethers, vinyl ketones (j) (sometimes referred to as monomers (j)):

[0134] Examples include vinyl esters of saturated fatty acids having 2 to 12 carbon atoms (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, etc.), alkyl, aryl or alkoxyalkyl vinyl ethers having 1 to 12 carbon atoms (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl-2-methoxyethyl ether, vinyl-2-butoxyethyl ether, etc.), and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms (methyl vinyl ketone, ethyl vinyl ketone, phenyl vinyl ketone, etc.).

[0135] Epoxy group-containing monomer (k) (sometimes referred to simply as monomer (k)):

[0136] Examples thereof include glycidyl (meth)acrylate and glycidyl (meth)allyl ether.

[0137] Monomer (l) containing a halogen element (sometimes simply referred to as monomer (l)):

[0138] Examples thereof include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrene (such as dichlorostyrene).

[0139] Ester of unsaturated polycarboxylic acid (m) (sometimes referred to simply as monomer (m)):

[0140] Examples include alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids [alkyl diesters of unsaturated dicarboxylic acids (such as maleic acid, fumaric acid and itaconic acid) having 1 to 8 carbon atoms (dimethyl maleate, dimethyl fumarate, diethyl maleate and dioctyl maleate)] and the like.

[0141] In the copolymer (A), from the perspective of preventing gelation, the weight ratio of the monomer (a) in the monomers constituting the copolymer (A) is 1 to 20% by weight, preferably 5 to 20% by weight, more preferably 8 to 18% by weight, and particularly preferably 10 to 17% by weight based on the total weight of the monomers constituting the copolymer (A). If the weight ratio of the monomer (a) is less than 1% by weight, the viscosity index improving effect tends to be easily reduced. If the weight ratio of the monomer (a) is greater than 20% by weight, the viscosity index improver composition tends to be easily gelated.

[0142] In the copolymer (A), the weight ratio of the monomer (b) in the monomers constituting the copolymer (A) is 45 to 85% by weight, preferably 50 to 85% by weight, and more preferably 55 to 80% by weight, based on the total weight of the monomers constituting the copolymer (A), from the viewpoint of preventing gelation and improving solubility in the base oil. If the weight ratio of the monomer (b) is less than 45% by weight, the viscosity index improver composition tends to gel easily, and if it is more than 85% by weight, the solubility of the copolymer (A) in the base oil (Fischer-Tropsch derived base oil (B) and other base oils) tends to deteriorate.

[0143] In the copolymer (A), from the viewpoint of the effect of reducing the HTHS viscosity at 100° C. and improving the viscosity index, the weight proportion of the monomer (c) in the monomers constituting the copolymer (A) is preferably 1 to 54% by weight, more preferably 1 to 53% by weight, further preferably 1 to 45% by weight, further more preferably 1 to 37% by weight, further preferably 1 to 35% by weight, and particularly preferably 2 to 30% by weight, based on the total weight of the monomers constituting the copolymer (A).

[0144] In the copolymer (A), from the viewpoint of the effect of reducing the HTHS viscosity at 100° C. and improving the viscosity index, the weight proportion of the monomer (d) in the monomers constituting the copolymer (A) is preferably 1 to 35% by weight, more preferably 1 to 20% by weight, and particularly preferably 5 to 15% by weight based on the total weight of the monomers constituting the copolymer (A).

[0145] In the copolymer (A), from the viewpoint of the effect of reducing the HTHS viscosity at 100° C. and improving the viscosity index, the total weight ratio of the monomers (e) to (m) in the monomers constituting the copolymer (A) is preferably 5% by weight or less, more preferably 1% by weight or less based on the total weight of the monomers constituting the copolymer (A).

[0146] The weight ratio of each of the monomers (b) to (m) in the copolymer (A) can be measured by a method such as thermal decomposition GC / MS. The weight ratio of the monomer (a) in the copolymer (A) can be determined, for example, as the weight ratio of the remaining components obtained by subtracting the weight of the monomers other than the monomer (a) measured by a method such as thermal decomposition GC / MS from the weight of the entire copolymer (A).

[0147] The Mw of the copolymer (A) is preferably 5,000 to 2,000,000 from the viewpoint of HTHS viscosity in the effective temperature range and low-temperature viscosity. The more preferred range varies depending on the use of the viscosity index improver composition and the lubricating oil composition containing the viscosity index improver composition, but is the range described in Table 2.

[0148] [Table 2]

[0149]

[0150] *: Automatic transmission oil

[0151] **: Belt-type continuously variable transmission oil

[0152] ***: Manual transmission fluid

[0153] The molecular weight distribution (Mw / Mn) of the copolymer (A) is preferably 1.0 to 4.0, more preferably 1.5 to 3.5, from the viewpoint of shear stability.

[0154] The measurement conditions of Mw and molecular weight distribution (Mw / Mn) of the copolymer (A) are the same as the measurement conditions of Mw and Mn of the above-mentioned monomer (a).

[0155] The SP value of the copolymer (A) is preferably 8.0 to 10.0 (cal / cm2) from the viewpoint of solubility in base oils (Fischer-Tropsch derived base oil (B) and other base oils) and viscosity index improvement effect. 3 ) 1 / 2 , more preferably 9.0 to 9.5 (cal / cm 3 ) 1 / 2 .

[0156] The SP value of the copolymer (A) is the value obtained by calculating the SP value of the structural unit (a structure in which the vinyl group becomes a single bond through polymerization reaction) derived from each monomer constituting the copolymer (A) using the above-mentioned SP value calculation method, and performing arithmetic averaging based on the weight fraction of each constituent monomer at the time of charging. For example, in the case where the monomer is methyl methacrylate, the structural unit derived from methyl methacrylate has 2 CH3, 1 CH2, 1 C, and 1 CO2 in terms of atomic groups. Therefore, the SP value of the structural unit derived from methyl methacrylate is 9.933 (cal / cm 3 ) 1 / 2 Calculated in the same way, the SP value of the structural unit derived from ethyl methacrylate is 9.721 (cal / cm 3 ) 1 / 2 .

[0157] ΣΔe i =1125×2+1180+350+4300=8080

[0158] Σv i =33.5×2+16.1-19.2+18.0=81.9

[0159] δ=(8080 / 81.9) 1 / 2 =9.933(cal / cm 3 ) 1 / 2

[0160] 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 calculated by taking the arithmetic mean based on the weight fraction of the SP value of the structural unit derived from each monomer as follows.

[0161] SP value of copolymer = (9.933 × 50 + 9.721 × 50) / 100 = 9.827

[0162] In addition, the SP value of the copolymer (A) can be adjusted to the desired range by appropriately adjusting the monomers and weight fractions used. Specifically, the SP value can be reduced by using more monomers with a large number of carbon atoms in the alkyl group, and the SP value can be increased by using more monomers with a small number of carbon atoms in the alkyl group.

[0163] The viscosity index improver composition of the present invention can be obtained by a known production method. Specifically, an example of a method in which the above-mentioned monomer is obtained by solution polymerization in a base oil (Fischer-Tropsch derived base oil (B), a base oil other than the Fischer-Tropsch derived base oil (B) described later, etc.) in the presence of a polymerization catalyst can be mentioned.

[0164] When the base oil during polymerization contains a Fischer-Tropsch derived base oil (B), the weight proportion of the Fischer-Tropsch derived base oil (B) in the base oil is preferably 20 to 100 wt %, more preferably 50 to 100 wt %, based on the weight of the base oil, from the perspective of preventing gelation.

[0165] Examples of polymerization catalysts include azo catalysts (2,2'-azobis(2-methylbutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile), peroxide catalysts (benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.), and redox catalysts (a mixture of benzoyl peroxide and a tertiary amine, etc.). In addition, a known chain transfer agent (alkyl mercaptan having 2 to 20 carbon atoms, etc.) may be used as needed to adjust the molecular weight.

[0166] The polymerization temperature is preferably 25 to 140° C., more preferably 50 to 120° C. In addition to the solution polymerization in the above base oil, the copolymer (A) can be obtained by bulk polymerization, emulsion polymerization or suspension polymerization and then dissolved in a base oil including a Fischer-Tropsch derived base oil (B) as required.

[0167] The copolymer (A) contained in the viscosity index improver composition may be in the form of a random addition polymer or an alternating copolymer, or may be a graft copolymer or a block copolymer.

[0168] <Fischer-Tropsch derived base oil (B)>

[0169] The viscosity index improver composition of the present invention comprises a 100°C kinematic viscosity of 4.0 mm 2 / s or less Fischer-Tropsch derived base oil (B). "Fischer-Tropsch derived" means that the base oil is a synthetic product of the Fischer-Tropsch process, or the base oil is derived from a synthetic product of the Fischer-Tropsch process. The Fischer-Tropsch process refers to the process of first producing a synthesis gas (or "syngas") containing carbon monoxide and hydrogen, and then converting it into hydrocarbons using a Fischer-Tropsch catalyst. For example, a substance obtained by producing synthesis gas from natural gas and converting it into hydrocarbons using a Fischer-Tropsch catalyst is called GTL oil (gas to liquid), a substance obtained by producing synthesis gas from coal and converting it into hydrocarbons using a Fischer-Tropsch catalyst is called CTL oil (coal to liquid, cold to liquid), and a substance obtained by producing synthesis gas from biomass and converting it into hydrocarbons using a Fischer-Tropsch catalyst is called BTL oil (biomass to liquid). These are all hydrocarbons with a narrow molecular weight distribution produced by reorganizing the molecular structure of synthesis gas, and their common point is that there are very few aromatic, nitrogen-based, sulfur-based compounds, etc. contained in mineral oils, etc.

[0170] In the present invention, it is presumed that the viscosity index improver composition contains the above-mentioned copolymer (A) in a base oil including the above-mentioned Fischer-Tropsch derived base oil (B) having a relatively low viscosity (small number of carbon atoms), and thus becomes a viscosity index improver composition that is less likely to produce a gel derived from the copolymer (A) due to the components in the above-mentioned Fischer-Tropsch derived base oil (B).

[0171] The Fischer-Tropsch derived base oil (B) may be at least one base oil selected from the group consisting of GTL oil, CTL oil and BTL oil. The Fischer-Tropsch derived base oil (B) may be a GTL oil and / or a CTL oil, or may be a GTL oil.

[0172] Kinematic viscosity of Fischer-Tropsch derived base oil (B) at 100°C (measured in accordance with JIS-K2283 (2000)) (unit: mm 2 When the kinematic viscosity of the Fischer-Tropsch derived base oil (B) at 100° C. is 4.0 or less, a viscosity index improver composition that is less likely to generate gel can be obtained.

[0173] From the viewpoint of preventing gelation, the Fischer-Tropsch derived base oil (B) has a kinematic viscosity at 100° C. of preferably 2.0 to 3.9, more preferably 2.4 to 3.5, and particularly preferably 2.7 to 3.5.

[0174] From the viewpoint of preventing gelation, the kinematic viscosity of the Fischer-Tropsch derived base oil (B) at 40°C (measured in accordance with JIS-K2283 (2000)) (unit: mm 2 / s, hereinafter abbreviated) is preferably 5.0 to 15.0, more preferably 6.0 to 12.0.

[0175] The viscosity index (measured in accordance with JIS-K2283 (2000)) of the Fischer-Tropsch derived base oil (B) is preferably 100 or more from the viewpoint of the viscosity index and low-temperature fluidity when prepared as a lubricating oil composition.

[0176] Whether the viscosity index improver composition contains the Fischer-Tropsch derived base oil (B) can be confirmed by, for example, the following method.

[0177] First, only the base oil is separated from the viscosity index improver composition by membrane separation or column treatment. Then, the contents of paraffins, cycloalkanes and aromatic compounds in the separated base oil are analyzed by mass spectrometry and NMR, thereby determining whether the base oil is a Fischer-Tropsch derived base oil or a base oil other than the Fischer-Tropsch derived base oil, such as a mineral oil. The kinematic viscosity of the Fischer-Tropsch derived base oil separated by the above method at 100°C is measured by the method of JIS-K2283 (2000), and it is determined whether the kinematic viscosity at 100°C is 4.0 mm / s. 2 / s or less, it can be confirmed that the viscosity index improver composition contains the Fischer-Tropsch derived base oil (B).

[0178] The viscosity index improver composition of the present invention may contain, in addition to the above-mentioned copolymer (A) and the above-mentioned Fischer-Tropsch derived base oil (B), a base oil other than the Fischer-Tropsch derived base oil [e.g., hydrocarbon oil {mineral oil (solvent refined oil, paraffin oil, high viscosity index oil containing isoparaffin, high viscosity index oil obtained by hydrogenation and decomposition of isoparaffin, and cycloparaffin oil, etc.), poly-α-olefin synthetic lubricating oil, etc.}, ester oil, etc.], (meth)acrylate alkyl ester (co)polymer (C) other than the above-mentioned copolymer (A), etc.

[0179] As the base oil other than the Fischer-Tropsch derived base oil (B), a base oil of Group I to V of the API (American Petroleum Institute) classification is preferred from the viewpoint of the solubility of the copolymer (A).

[0180] From the viewpoint of viscosity index and HTHS viscosity at operating temperature, the kinematic viscosity at 100°C (measured in accordance with JIS-K2283 (2000)) (unit: mm 2 / s, hereinafter abbreviated) is preferably 1.5 to 6.0, more preferably 2.0 to 5.0.

[0181] The viscosity index (measured in accordance with JIS-K2283 (2000)) of the base oil other than the Fischer-Tropsch derived base oil (B) is preferably 100 or more, more preferably 110 or more, from the viewpoint of HTHS viscosity in the effective temperature range.

[0182] From the viewpoint of viscosity index and HTHS viscosity at the operating temperature, the kinematic viscosity at 40°C (measured in accordance with JIS-K2283 (2000)) (unit: mm 2 / s, hereinafter abbreviated) is preferably 5.0 to 38.0, more preferably 7.0 to 25.0.

[0183] When the viscosity index improver composition contains a base oil other than the Fischer-Tropsch derived base oil (B), the kinematic viscosity (measured in accordance with JIS-K2283 (2000)) at 100° C. (unit: mm) of the base oil as a whole (the base oil as a whole blended with the Fischer-Tropsch derived base oil (B) and the base oil other than the Fischer-Tropsch derived base oil (B)) contained in the viscosity index improver composition is 100° C. from the viewpoint of preventing gelation. 2 / s, hereinafter abbreviated) is preferably 1.5 to 5.0, more preferably 2.0 to 4.5, and particularly preferably 2.4 to 4.3.

[0184] When the viscosity index improver composition contains a base oil other than the Fischer-Tropsch derived base oil (B), the kinematic viscosity (measured in accordance with JIS-K2283 (2000)) at 40° C. (unit: mm) of the base oil as a whole (the base oil as a whole blended with the Fischer-Tropsch derived base oil (B) and the base oil other than the Fischer-Tropsch derived base oil (B)) contained in the viscosity index improver composition is 100% by weight from the viewpoint of preventing gelation. 2 / s, hereinafter abbreviated) is preferably 5.0 to 15.0, more preferably 6.0 to 12.0.

[0185] <(Co)polymer (C)>

[0186] From the viewpoint of reducing the low-temperature viscosity, the viscosity index improver composition preferably contains an alkyl (meth)acrylate (co)polymer (C).

[0187] The (co)polymer (C) includes a (co)polymer that does not contain the monomer (a), and examples thereof include a (co)polymer having a (meth)acryloyl monomer (c) having an alkyl group having 9 to 36 carbon atoms as an essential constituent monomer. Specifically, there can be mentioned n-dodecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate and n-octadecyl (meth)acrylate copolymers, n-octadecyl (meth)acrylate / n-dodecyl (meth)acrylate (molar ratio 10 to 30 / 90 to 70) copolymers, n-tetradecyl (meth)acrylate / n-dodecyl (meth)acrylate (molar ratio 10 to 30 / 90 to 70) copolymers, n-hexadecyl (meth)acrylate / n-dodecyl (meth)acrylate / methyl (meth)acrylate (molar ratio 20 to 40 / 55 to 75 / 0 to 10) copolymers, and n-dodecyl acrylate / n-dodecyl methacrylate (molar ratio 10 to 40 / 90 to 60) copolymers, and the like. These may be used alone or in combination of two or more.

[0188] From the viewpoint of lowering the pour point temperature, the Mw of the (co)polymer (C) is preferably 5,000 to 100,000, more preferably 10,000 to 80,000.

[0189] 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 Fischer-Tropsch derived base oil (B).

[0190] In addition, the measurement conditions of Mw of the (co)polymer (C) are the same as the measurement conditions of Mw of the above-mentioned monomer (a).

[0191] <Viscosity Index Improver Composition>

[0192] The viscosity index improver composition of the present invention comprises the above copolymer (A) and a 100° C. kinematic viscosity of 4.0 mm 2 / s or less.

[0193] From the viewpoint of handling properties, the content of the copolymer (A) in the viscosity index improver composition of the present invention is preferably 10 to 30% by weight, more preferably 15 to 25% by weight, based on the weight of the viscosity index improver composition.

[0194] From the aspect of handling, the content of the Fischer-Tropsch derived base oil (B) in the viscosity index improver composition of the present invention is preferably 2% by weight or more, more preferably 5% by weight or more, further preferably 20% by weight or more, and particularly preferably 25% by weight or more, based on the weight of the viscosity index improver composition. As an upper limit, it is preferably 90% by weight or less, and further preferably 85% by weight or less. As a preferred range, it is preferably 2 to 90% by weight, more preferably 5 to 90% by weight, further preferably 20 to 90% by weight, and particularly preferably 25 to 90% by weight.

[0195] From the viewpoint of handling properties, the content of the base oil other than the Fischer-Tropsch derived base oil (B) in the viscosity index improver composition of the present invention is preferably 78 wt % or less, more preferably 68 wt % or less, based on the weight of the viscosity index improver composition.

[0196] From the perspective of handling, the ratio of the weight of the copolymer (A) to the weight of the Fischer-Tropsch derived base oil (B) {(A) / (B)} in the viscosity index improver composition of the present invention is preferably 0.05 to 10, more preferably 0.1 to 4.0, further preferably 0.1 to 2.5, particularly preferably 0.1 to 1.1, and most preferably 0.1 to 1.0.

[0197] From the viewpoint of handling properties, the content of the Fischer-Tropsch derived base oil (B) in the viscosity index improver composition of the present invention is preferably 5 wt% or more, more preferably 25 wt% or more, particularly preferably 50 wt% or more, based on the total weight of the base oils contained in the viscosity index improver composition.

[0198] From the viewpoint of handling properties, the content of the base oil other than the Fischer-Tropsch derived base oil (B) in the viscosity index improver composition of the present invention is preferably 95 wt% or less, more preferably 75 wt% or less, particularly preferably 50 wt% or less, based on the total weight of the base oil contained in the viscosity index improver composition.

[0199] From the viewpoint of reducing low-temperature viscosity, the content of the (co)polymer (C) in the viscosity index improver composition of the present invention is preferably 0.01 to 30% by weight, more preferably 0.01 to 10% by weight, based on the weight of the copolymer (A).

[0200] The viscosity index improver composition of the present invention does not easily generate gel, and the lubricating oil composition containing the viscosity index improver composition of the present invention can be suitably used in gear oil (differential oil and industrial gear oil, etc.), MTF, transmission oil [ATF, DCTF and belt CVTF, etc.], traction oil (annular CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (hydraulic oil for construction machinery and industrial hydraulic oil, etc.) and engine oil (for gasoline engines and diesel engines), and can be particularly suitably used as a lubricating oil composition for internal combustion engines, especially a lubricating oil composition for hybrid vehicles.

[0201] <Lubricating Oil Composition>

[0202] The lubricating oil composition of the present invention contains the viscosity index improver composition of the present invention and at least one additive selected from the group consisting of a detergent, a dispersant, an antioxidant, an oiliness improver, a pour point depressant, a friction and wear modifier, an extreme pressure agent, a defoamer, an anti-emulsifier, a metal deactivator and a corrosion inhibitor.

[0203] It is presumed that by using the viscosity index improver composition of the present invention, the extension of the side chain derived from the monomer (a) as a constituent monomer of the copolymer (A) is influenced by the presence of the components in the Fischer-Tropsch derived base oil (B), and the viscosity index of the lubricating oil composition can be further improved.

[0204] From the viewpoint of viscosity index and HTHS viscosity, the content of the viscosity index improver composition in the lubricating oil composition is preferably 1.5 to 30% by weight, more preferably 2 to 20% by weight, based on the weight of the lubricating oil composition.

[0205] From the viewpoint of viscosity index improvement effect and cost, the content of the copolymer (A) in the lubricating oil composition of the present invention is preferably 0.1 wt% or more and less than 10 wt%, more preferably 0.5 to 3 wt%, based on the weight of the lubricating oil composition.

[0206] From the viewpoint of reducing fuel consumption and cost, the content of the Fischer-Tropsch derived base oil (B) in the lubricating oil composition is preferably 0.4 to 27% by weight, more preferably 1 to 20% by weight, based on the weight of the lubricating oil composition.

[0207] From the viewpoint of reducing low-temperature viscosity, the content of the (co)polymer (C) in the lubricating oil composition of the present invention is preferably 0.01 to 5% by weight based on the weight of the lubricating oil composition.

[0208] From the viewpoint of reducing fuel consumption and cost, the content of the base oil other than the Fischer-Tropsch derived base oil (B) in the lubricating oil composition of the present invention is preferably 43 to 94 wt %, more preferably 57 to 93 wt %, based on the weight of the lubricating oil composition.

[0209] Examples of the additives in the present invention include the following additives.

[0210] (1) Cleaning agent:

[0211] Basic, overbased or neutral metal salts [overbased or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzene sulfonates and alkylnaphthalene sulfonates, etc.)], salicylates, phenates, naphthenates, carbonates, phosphonates and mixtures thereof;

[0212] (2) Dispersant:

[0213] Succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates and borates, etc.;

[0214] (3) Antioxidants:

[0215] Hindered phenols and aromatic secondary amines, etc.;

[0216] (4) Oiliness improver:

[0217] 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.;

[0218] (5) Pour Point Depressant

[0219] Polyalkyl methacrylate, ethylene-vinyl acetate copolymer, etc.;

[0220] (6) Friction and wear modifier:

[0221] Molybdenum and zinc compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate and zinc dialkyl dithiophosphate, etc.);

[0222] (7) Extreme pressure agent:

[0223] Sulfur compounds (monosulfide or disulfide, sulfoxide and sulfur-phosphorus compounds), phosphorus compounds and chlorine compounds (chlorinated paraffins, etc.);

[0224] (8) Defoaming agent:

[0225] Silicone oil, metal soap, fatty acid ester and phosphate compounds, etc.;

[0226] (9) Anti-emulsifier:

[0227] Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphate esters (phosphate esters containing polyoxyethylene nonionic surfactants, etc.), hydrocarbon solvents (toluene, xylene, ethylbenzene), etc.;

[0228] (10) Metal passivator

[0229] Compounds containing nitrogen atoms (benzotriazole, etc.), chelated compounds containing nitrogen atoms (N,N'-disalicylidene-1,2-diaminopropane, etc.), compounds containing nitrogen / sulfur atoms (2-(n-dodecylthio)benzimidazole, etc.), etc.;

[0230] (11) Anticorrosive agents:

[0231] Compounds containing nitrogen atoms (benzotriazole and 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, etc.)

[0232] Only one of these additives may be added, or two or more additives may be added as needed. In addition, a mixture of these additives is sometimes referred to as a performance additive or a packaging additive, and such additives may be added.

[0233] The content of each of these additives is preferably 0.1 to 15% by weight based on the total amount of the lubricating oil composition. The total content of each additive is preferably 0.1 to 30% by weight, more preferably 0.3 to 20% by weight, and even more preferably 3 to 10% by weight based on the total amount of the lubricating oil composition.

[0234] When the lubricating oil composition is used as an engine oil (0W-16), the viscosity index (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 250 to 290, more preferably 260 to 280 from the viewpoint of fuel efficiency.

[0235] When the lubricating oil composition is used as an engine oil (0W-20), the viscosity index (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 300 to 330, more preferably 310 to 325, from the viewpoint of fuel efficiency.

[0236] It should be noted that "0W-16" and "0W-20" refer to the viscosity of the oil that meets the SAE regulations of 0W-16 or 0W-20 {"0W" refers to the viscosity index (Winter Grade) when the engine is cold (when the engine is started), and "16" and "20" indicate the viscosity of the oil when the engine is hot}.

[0237] When the lubricating oil composition is used as engine oil (0W-16), the HTHS viscosity (100° C.) (based on ASTM D4683) of the lubricating oil composition is preferably 3.50 to 4.50 mPa·s, more preferably 3.60 to 4.30 mPa·s, from the viewpoint of fuel efficiency.

[0238] When the lubricating oil composition is used as engine oil (0W-20), the HTHS viscosity (100° C.) (based on ASTM D4683) of the lubricating oil composition is preferably 4.00 to 5.00 mPa·s, more preferably 4.10 to 4.70 mPa·s, from the viewpoint of fuel efficiency.

[0239] When the lubricating oil composition is used as an engine oil (0W-16), the kinematic viscosity (100° C.) (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 6.00 to 6.70 mm / s from the viewpoint of fuel efficiency. 2 / s, more preferably 6.10 to 6.60 mm 2 / s.

[0240] When the lubricating oil composition is used as an engine oil (0W-20), the kinematic viscosity (100° C.) (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 7.40 to 7.80 mm / s from the viewpoint of fuel efficiency. 2 / s, more preferably 7.50 to 7.70 mm 2 / s.

[0241] When the lubricating oil composition is used as an engine oil (0W-16), the kinematic viscosity (40° C.) (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 21.0 to 23.5 mm / s from the viewpoint of fuel efficiency. 2 / s, more preferably 21.2 to 23.0 mm 2 / s.

[0242] When the lubricating oil composition is used as an engine oil (0W-20), the kinematic viscosity (40° C.) (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition is preferably 22.0 to 25.0 mm / s from the viewpoint of fuel efficiency. 2 / s, more preferably 22.2 to 24.5 mm 2 / s.

[0243] The lubricating oil composition of the present invention is suitable for use in gear oils (differential oils and industrial gear oils, etc.), MTF, transmission oils [ATF, DCTF, belt-type CVTF, etc.], traction oils (annular CVTF, etc.), shock absorber oils, power steering oils, hydraulic oils (hydraulic oils for construction machinery and industrial hydraulic oils, etc.) and engine oils (for gasoline engines and diesel engines), and can be particularly suitably used as a lubricating oil composition for internal combustion engines, especially a lubricating oil composition for hybrid vehicles.

[0244] The following matters are disclosed in this specification.

[0245] The present disclosure (1) relates to a viscosity index improver composition comprising a copolymer (A) and a 100° C. kinematic viscosity of 4.0 mm 2 / s or less, the copolymer (A) comprising a polyolefin monomer (a) represented by the following general formula (1) and an alkyl (meth)acrylate (b) having an alkyl group with 1 to 4 carbon atoms as essential constituent monomers, wherein the content of the monomer (a) is 1 to 20% by weight and the content of the alkyl (meth)acrylate (b) is 45 to 85% by weight, based on the total weight of the monomers constituting the copolymer (A).

[0246] [Chemistry 4]

[0247]

[0248] [In the general formula (1), R 1 is a hydrogen atom or a methyl group; -X 1 - is -O-, -O(AO) m - or -NH-, A is an alkylene group having 2 to 4 carbon atoms, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R 2 It is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit; p is a number of 0 or 1.]

[0249] The present disclosure (2) relates to the viscosity index improver composition described in the present disclosure (1), wherein the ratio of the weight of the above-mentioned copolymer (A) to the weight of the above-mentioned Fischer-Tropsch derived base oil (B) {(A) / (B)} contained in the viscosity index improver composition is 0.05 to 10.

[0250] The present disclosure (3) relates to the viscosity index improver composition described in the present disclosure (1) or (2), wherein the solubility parameter of the copolymer (A) is 8.0 to 10.0 (cal / cm 3 ) 1 / 2 .

[0251] The present disclosure (4) relates to the viscosity index improver composition according to any one of the present disclosures (1) to (3), wherein the copolymer (A) is a copolymer containing a (meth)acryloyl monomer (c) having an alkyl group having 9 to 36 carbon atoms as a constituent monomer.

[0252] The present disclosure (5) relates to the viscosity index improver composition described in the present disclosure (4), wherein the copolymer (A) is a copolymer containing a monomer (d) represented by the following general formula (2) as a constituent monomer.

[0253] [Chemistry 5]

[0254]

[0255] [In 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; R 5 is an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 20 carbon atoms; q is an integer of 1 to 20, and when q is 2 or more, R 4 Can be the same or different.]

[0256] The present disclosure (6) relates to the viscosity index improver composition described in the present disclosure (5), wherein the copolymer (A) contains 1 to 53% by weight of the monomer (c) and 1 to 35% by weight of the monomer (d) as constituent monomers based on the total weight of the monomers constituting (A).

[0257] The present disclosure (7) relates to the viscosity index improver composition according to any one of the present disclosures (1) to (6), wherein the weight average molecular weight of the copolymer (A) is 5,000 to 2,000,000.

[0258] The present disclosure (8) relates to the viscosity index improver composition according to any one of the present disclosures (1) to (7), which contains a base oil of API Groups I to V other than the Fischer-Tropsch derived base oil (B).

[0259] The present disclosure (9) relates to a lubricating oil composition comprising the viscosity index improver composition described in any one of the present disclosures (1) to (8), and at least one additive selected from the group consisting of a detergent, a dispersant, an antioxidant, an oiliness improver, a pour point depressant, a friction and wear modifier, an extreme pressure agent, a defoamer, an anti-emulsifier, a metal deactivator and a corrosion inhibitor.

[0260] Example

[0261] The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0262] <Production Example 1>

[0263] In a SUS pressure-resistant reaction vessel equipped with a temperature control device and a stirrer, 400 parts by weight of degassed and dehydrated hexane, 1 part by weight of tetrahydrofuran, 75 parts by weight of 1,3-butadiene, and 2 parts by weight of n-butyllithium were charged, and polymerization was then carried out at a polymerization temperature of 70°C.

[0264] 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 3 hours. To stop the reaction, 50 parts by weight of water and 25 parts by weight of a 1N hydrochloric acid aqueous solution were added and stirred at 80°C for 1 hour. The organic phase of the reaction solution was recovered with a separatory funnel, heated to 70°C, and the solvent was removed under a reduced pressure of 0.027 to 0.040 MPa for 2 hours.

[0265] 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 make it uniformly dissolved. After injecting a suspension prepared by mixing 10 parts by weight of palladium carbon and 50 parts by weight of tetrahydrofuran in advance, hydrogen was supplied to the liquid at a flow rate of 30 mL / min from the hydrogen introduction tube, and the reaction was carried out at room temperature for 8 hours. After that, the palladium carbon was removed by filtration, and the obtained filtrate was heated to 70°C, and tetrahydrofuran was removed under a reduced pressure of 0.027 to 0.040 MPa to obtain a polymer (Y1-1) containing a hydroxyl group at one end of hydrogenated polybutadiene (total ratio of isobutylene and 1,2-butylene: 45 mol%, 1,2-adduct / 1,4-adduct (molar ratio): 45 / 55, hydroxyl value: 8.0 mgKOH / g, crystallization temperature: -60°C or less).

[0266] 245 parts by weight of a polymer (Y1-1) containing a hydroxyl group at one end of hydrogenated polybutadiene, 245 parts by weight of methacrylic acid, and 98 parts by weight of an inorganic porous body supporting a sulfonic acid group (acid value 45 mgKOH / g, particle size 240 μm) were added, and esterification was carried out at 120°C. Next, the inorganic porous body supporting a sulfonic acid group was removed by filtration, and excess methacrylic acid was removed from the reaction solution under reduced pressure (0.027 to 0.040 MPa) to obtain a monomer (a-1). The molecular weight of the obtained monomer (a-1) was measured by GPC, and the molecular weight of the obtained monomer (a-1) was measured by 13 The ratio of 1,2-butylene groups was measured by C-NMR. The results showed that Mw = 6,900, Mn = 6,800, the ratio of 1,2-butylene groups = 45 mol%, and -X in the general formula (1) 1 - is a group represented by -O(CH2CH2O)1-, and p=0.

[0267] <Production Example 2>

[0268] Into a 1L SUS pressure-resistant reaction vessel equipped with a temperature control device and a stirrer, 400 parts by weight of degassed and dehydrated hexane, 1 part by weight of tetrahydrofuran, and 0.4 parts by weight of n-butyl lithium were placed, and then cooled to -40°C. 90 parts by weight of 1,3-butadiene liquefied at -40°C was added thereto, and the polymerization temperature was set at -40°C for polymerization. Thereafter, the same process as in Production Example 1 was carried out to obtain a polymer (Y1-2) containing a hydroxyl group at one end of a hydrogenated polybutadiene (total ratio of isobutylene and 1,2-butylene: 65 mol%, 1,2-adduct / 1,4-adduct (molar ratio): 65 / 35, hydroxyl value: 13.1 mgKOH / g, crystallization temperature: below -60°C). (Y1-2) was further esterified with methacrylic acid to obtain a monomer (a-2). The molecular weight of the obtained monomer (a-2) was measured by GPC, and the molecular weight was determined by 13 The ratio of 1,2-butylene groups was measured by C-NMR. The results showed that Mw = 6,900, Mn = 6,800, the ratio of 1,2-butylene groups = 65 mol%, and -X in the general formula (1) 1 - is a group represented by -O(CH2CH2O)1-, and p=0.

[0269] <Example 1>

[0270] In Example 1, a viscosity index improver composition (R-1) described in Table 4 and containing the copolymer (A-1) described in Table 3 was obtained by the following method. First, a total of 100 parts by weight of the monomer mixture for producing the copolymer (A) described in Table 3 and a total of 200 parts by weight of the base oil described in Table 4 were added to a reaction vessel equipped with a stirring device, a heating and cooling device, a thermometer, and a nitrogen inlet pipe. After nitrogen substitution (gas phase oxygen concentration 100 ppm), the temperature was raised to 76° C. while stirring in a sealed state, and then a polymerization catalyst (2,2'-azobis(2-methylbutyronitrile)) in an amount described in Table 3 was added, and a polymerization reaction was carried out at the same temperature for 4 hours. The temperature was raised to 90° C., reacted for 2 hours, and then raised to 120 to 130° C. The dilution base oil described in Table 4 was added thereto to obtain a viscosity index improver composition (R-1) containing the copolymer (A-1). The SP value of the obtained copolymer (A-1) was calculated by the above method, and Mw and Mn were measured by the above method. The results are shown in Table 4. In addition, KV100 in Tables 4 to 12 means the kinematic viscosity at 100°C.

[0271] <Examples 2 to 17, Comparative Examples 1 to 13>

[0272] Viscosity index improver compositions (R-2 to R-17, S-1 to S-13) containing the copolymer (A) were obtained in the same manner as in Example 1 except that the amounts of the monomer compound and the polymerization catalyst were as shown in Table 3, and the amounts of the base oil and the dilution base oil during polymerization were as shown in Tables 4 to 12.

[0273] [Table 3]

[0274]

[0275] Table 4

[0276]

[0277] [Table 5]

[0278]

[0279] [Table 6]

[0280]

[0281] [Table 7]

[0282]

[0283] [Table 8]

[0284]

[0285] [Table 9]

[0286]

[0287] [Table 10]

[0288]

[0289] [Table 11]

[0290]

[0291] [Table 12]

[0292]

[0293] The compositions of the monomers (a) to (d) described in Table 3 are as follows.

[0294] (a-1): Methacrylate of (Y1-1) [Mn: 6800]

[0295] (a-2): Methacrylate of (Y1-2) [Mn: 6800]

[0296] (b-1): Methyl methacrylate

[0297] (b-2): Ethyl methacrylate

[0298] (b-3): n-Butyl methacrylate

[0299] (c-1): n-Dodecyl methacrylate

[0300] (c-2): a mixture of linear and branched alkyl methacrylates having 12 to 13 carbon atoms (methacrylate of Neodol 23 manufactured by Shell (mixture of weight ratio = linear C12: branched C12: linear C13: branched C13 = 40:10:40:10))

[0301] (c-3): a mixture of linear and branched alkyl methacrylates having 14 to 15 carbon atoms (methacrylate of Neodol 45 manufactured by Shell (mixture of weight ratio = linear C14: branched C14: linear C15: branched C15 = 40:10:40:10))

[0302] (c-4): n-hexadecyl methacrylate

[0303] (c-5): n-octadecyl methacrylate

[0304] (d-1): n-Butoxyethyl methacrylate

[0305] The SP value of the structural unit (a-1), (a-2), (c-2), and (c-3) derived from each monomer (a-1), (a-2), (c-2), and (c-3) is calculated based on the following mathematical formula.

[0306] Structural unit from (a-1)

[0307] ΣΔe i =1125(CH3)+1180(CH2)+350(C)+4300(CO2)=6955

[0308] Σv i =33.5(CH3)+16.1(CH2)-19.2(C)+18.0(CO2)=48.4

[0309] ΣΔe i =1180(CH2)×2+800(O)=3160

[0310] Σv i =16.1(CH2)×2+3.8(O)=36

[0311] ΣΔe i=1180(CH2)×2+1125(CH3)+820(CH)=4305

[0312] Σv i =16.1(CH2)×2+33.5(CH3)-1.0(CH)=64.7

[0313] ΣΔe i =1180(CH2)×4=4720

[0314] Σv i =16.1(CH2)×4=64.4

[0315] Here, the total number of 1,2-butylene groups and 1,4-butylene groups is as follows.

[0316] Total number of 1,2-butylene and 1,4-butylene = (6800-85-44) / 56 = 119.125

[0317] Therefore, the parameters of the structural unit derived from (a-1) are as follows.

[0318] ΣΔe i =6955+3160+4305×119.125×0.45+4720×119.125×0.55=550138.4

[0319] Σv i =48.4+36+64.7×119.125×0.45+64.4×119.125×0.55=7772.132

[0320] SP value = (ΣΔe i / Σv i ) 1 / 2 =(550138.4 / 7772.132) 1 / 2 =8.413

[0321] Structural unit from (a-2)

[0322] Total number of 1,2-butylene and 1,4-butylene = (6800-85-44) / 56 = 119.125

[0323] ΣΔe i =6955+3160+4305×119.125×0.65+4720×119.125×0.35=540251

[0324] Σv i=48.4+36+64.7×119.125×0.65+64.4×119.125×0.35=7779.279

[0325] SP value = (ΣΔe i / Σv i ) 1 / 2 =(540251 / 7779.279) 1 / 2 =8.334

[0326] Structural unit from (c-2)

[0327] Straight chain C12

[0328] ΣΔe i =6955+1180×11+1125=21060

[0329] Σv i =48.4+16.1×11+33.5=259

[0330] SP value = (ΣΔe i / Σv i ) 1 / 2 =(21060 / 259) 1 / 2 =9.017

[0331] Branched C12

[0332] ΣΔe i =6955+1180×9+1125×2+820=20645

[0333] Σv i =48.4+16.1×9+33.5×2-1.0=259.3

[0334] SP value = (ΣΔe i / Σv i ) 1 / 2 =(20645 / 259.3) 1 / 2 =8.923

[0335] Straight chain C13

[0336] ΣΔe i =6955+1180×12+1125=22240

[0337] Σv i =48.4+16.1×12+33.5=275.1

[0338] SP value = (ΣΔe i / Σv i ) 1 / 2=(22240 / 275.1) 1 / 2 =8.991

[0339] Branched C13

[0340] ΣΔe i =6955+1180×10+1125×2+820=21825

[0341] Σv i =48.4+16.1×10+33.5×2-1.0=275.4

[0342] SP value = (ΣΔe i / Σv i ) 1 / 2 =(21825 / 275.4) 1 / 2 =8.902

[0343] SP value of the structural unit derived from (c-2) = (9.017×40+8.923×10+8.991×40+8.902×10) / 100 = 8.986

[0344] Structural unit from (c-3)

[0345] Straight chain C14

[0346] ΣΔe i =6955+1180×13+1125=23420

[0347] Σv i =48.4+16.1×13+33.5=291.2

[0348] SP value = (ΣΔe i / Σv i ) 1 / 2 =(23420 / 291.2) 1 / 2 =8.968

[0349] Branched C14

[0350] ΣΔe i =6955+1180×11+1125×2+820=23005

[0351] Σv i =48.4+16.1×11+33.5×2-1.0=291.5

[0352] SP value = (ΣΔe i / Σv i ) 1 / 2 =(23005 / 291.5) 1 / 2 =8.884

[0353] Straight chain C15

[0354] ΣΔe i =6955+1180×14+1125=24600

[0355] Σv i =48.4+16.1×14+33.5=307.3

[0356] SP value = (ΣΔe i / Σv i ) 1 / 2 =(24600 / 307.3) 1 / 2 =8.947

[0357] Branched C15

[0358] ΣΔe i =6955+1180×12+1125×2+820=24185

[0359] Σv i =48.4+16.1×12+33.5×2-1.0=307.6

[0360] SP value = (ΣΔe i / Σv i ) 1 / 2 =(24185 / 307.6) 1 / 2 =8.867

[0361] SP value of the structural unit derived from (c-3) = (8.968×40+8.884×10+8.947×40+8.867×10) / 100 = 8.941

[0362] In addition, the base oils described in Tables 4 to 12 used were as follows.

[0363] Hydrocarbon oil-1: manufactured by SK Lubricants, product name "Yubase 4", API Class III (kinematic viscosity at 100°C: 4.21 mm 2 / s, kinematic viscosity at 40°C: 19.12mm 2 / s)

[0364] Hydrocarbon oil-2: manufactured by SK Lubricants, product name "Yubase 3", API Class III (kinematic viscosity at 100°C: 3.06 mm 2 / s, kinematic viscosity at 40°C: 12.25mm 2 / s)

[0365] Hydrocarbon oil-3: manufactured by S Oil Co., Ltd., product name "Ultra S-2", API Class II (kinematic viscosity at 100°C: 2.28 mm 2 / s, kinematic viscosity at 40°C: 7.79mm 2 / s)

[0366] GTL oil-1: manufactured by Shell, XHVI4, kinematic viscosity at 100°C: 4.08 mm 2 / s, kinematic viscosity at 40°C: 18.22mm 2 / s

[0367] GTL oil-2: Shell, Ondina X415, kinematic viscosity at 100°C: 2.70 mm 2 / s, kinematic viscosity at 40°C: 9.80mm 2 / s

[0368] GTL oil-3: Shell Chemicals, GS310, kinematic viscosity at 100°C: 2.05 mm 2 / s, kinematic viscosity at 40°C: 6.02mm 2 / s

[0369] GTL oil-4: manufactured by Shell Chemicals, GS270, kinematic viscosity at 100°C: 1.32 mm 2 / s, kinematic viscosity at 40°C: 3.38mm 2 / s

[0370] CTL oil-1: manufactured by Shanxi Lu'an Taihang Lubrication Technology Co., Ltd., ICCSYN3, kinematic viscosity at 100°C: 2.96mm 2 / s, kinematic viscosity at 40°C: 11.20mm 2 / s

[0371] Ester oil-1: API Classification V (di(2-ethylhexyl) sebacate, kinematic viscosity at 100°C: 3.23 mm 2 / s, kinematic viscosity at 40°C: 11.53mm 2 / s)

[0372] Among the base oils described in Tables 4 to 12, GTL oil-2, GTL oil-3, GTL oil-4, and CTL oil-1 contain a base oil having a kinematic viscosity of 4.0 mm at 100°C. 2 / s or less in the Fischer-Tropsch derived base oil (B). The 100°C kinematic viscosity in Tables 4 to 12 is 4.0 mm 2The content (weight %) of the Fischer-Tropsch derived base oil (B) having a viscosity index improver composition of 0.0447 W / s or less is the total value of the contents of GTL oil-2, GTL oil-3, GTL oil-4 and CTL oil-1.

[0373] <Method for measuring kinematic viscosity of the entire blended base oil>

[0374] For the viscosity index improver compositions of Examples 1 to 17 and Comparative Examples 1 to 13, only the base oil for polymerization and the base oil for dilution were separately mixed to obtain base oil blends. The kinematic viscosity of the base oil blends at 40° C. and 100° C. was measured by the method of JIS-K2283 (2000). The viscosity index was also calculated by the method of JIS-K2283 (2000).

[0375] <Gelation Test of Viscosity Index Improver Composition - Rheometer>

[0376] The gelation test of the viscosity index improver composition in the present specification was carried out under the following conditions using a rheometer (rheometer "Physica MCR302" manufactured by Antonpaar).

[0377] Measuring fixture: parallel plate (diameter 50mm)

[0378] Temperature control: Peltier on lower surface

[0379] Gap: 0.5mm

[0380] Dependence: 1%

[0381] Frequency: 1Hz

[0382] Heating speed: 5℃ / min (10-100℃)

[0383] Cooling speed: 2℃ / min (100-10℃)

[0384] Heating / cooling pattern before gelling judgment: Heating → Cooling → Heating → Cooling

[0385] <Weight Ratio (A) / (B) in Viscosity Index Improver Composition>

[0386] Tables 4 to 12 show the ratio of the weight of the copolymer (A) to the weight of the Fischer-Tropsch derived base oil (B) contained in the viscosity index improver composition.

[0387] <Solubility Test of Samples after Gelation Test>

[0388] The sample (30.0 g) immediately after the gelation test and hydrocarbon oil-1 (Yubase 4, kinematic viscosity at 100° C.: 4.21 mm) were placed in a reaction container equipped with a stirring device, a heating and cooling device, and a thermometer. 2 / s, kinematic viscosity at 40°C: 19.12mm 2 / s), the stirring speed was 50 rpm, the temperature was adjusted to 50°C, and sampling (3 g) was performed every 15 minutes. The kinematic viscosity (40°C) of the sampled sample was measured, and the time when the difference in kinematic viscosity between the two measurements was within 0.5% was taken as the end point of solubility. The time from the start of stirring to the sampling of the first sample of the two samples with a kinematic viscosity difference within 0.5% was taken as the dissolution time of the sample after the gelation test, and is shown in Tables 4 to 12. The shorter the dissolution time of the sample after the gelation test, the less gel is produced in the viscosity index improver composition.

[0389] The kinematic viscosity (40° C.) was measured using a Stabinger viscometer (SVM3001) manufactured by Anton-Paar in accordance with the method of ASTM D 7042.

[0390] <Examples 18 to 25, Comparative Example 14 (Evaluation as 0W-16 Grade)>

[0391] In a stainless steel container equipped with a stirring device, Yubase 4 (100° C. kinematic viscosity: 4.21 mm 2 / s, kinematic viscosity at 40°C: 19.12mm 2 / s), Yubase3(3.06mm 2 / s, kinematic viscosity at 40°C: 12.25mm 2 / s) and a packaged additive for engine oil (Infineum P-5741, 10 wt% of the total), the kinematic viscosity of the lubricating oil composition obtained at 100°C was 6.5 mm 2 The viscosity index improver compositions (R-1) to (R-9), (R-12) or (S-1) were added respectively so that the NOACK evaporation amount was 22% to obtain lubricating oil compositions (V-1) to (V-8) and (W-1).

[0392] The shear stability, HTHS viscosity (150°C, 100°C), kinematic viscosity (40°C, 100°C), viscosity index, and solubility in the base oil containing additives of the lubricating oil compositions (V-1) to (V-8) and (W-1) were measured by the following methods. The results are shown in Table 13.

[0393] <Method for measuring NOACK evaporation amount of lubricating oil composition>

[0394] The measurement was performed in accordance with the method of ASTM D 5800 (measurement conditions: 250° C., 1 hour).

[0395] <Method for measuring HTHS viscosity of lubricating oil composition>

[0396] The measurement was carried out at 150°C and 100°C by the method of ASTM D 4683.

[0397] <Method for measuring viscosity of lubricating oil composition>

[0398] The kinematic viscosity at 40°C and 100°C was measured by the method of JIS-K2283 (2000), and the viscosity index was calculated by the method of JIS-K2283 (2000). A larger value of the viscosity index means a greater effect of improving the viscosity index.

[0399] <Method for measuring and calculating shear stability of lubricating oil composition>

[0400] The shear stability is measured by the method of ASTM D 6278 and calculated by the method of ASTM D 6022. The smaller the value, the higher the shear stability.

[0401] <Evaluation Method of Solubility of Copolymer in Base Oil Containing Additives>

[0402] The appearances of the lubricating oil compositions (V-1) to (V-8) and (W-1) were visually observed, and the base oil solubility was evaluated according to the following evaluation criteria.

[0403] [Evaluation criteria]

[0404] ○: Uniform appearance, no insoluble matter

[0405] ×: Uneven appearance, insoluble matter observed

[0406]

[0407] From the results in Tables 4 to 12, it can be seen that the following copolymer (A) has a kinematic viscosity of 4.0 mm at 100°C. 2 The viscosity index improver composition of a Fischer-Tropsch derived base oil (B) with a viscosity index of less than 1:1 is not easy to produce gels and has a fast dissolution time when preparing lubricating oil. The copolymer (A) contains a polyolefin monomer (a) represented by the general formula (1) and an alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms (b) as essential constituent monomers, wherein the content of the monomer (a) is 1 to 20% by weight and the content of the monomer (b) is 45 to 85% by weight.

[0408] Furthermore, as can be seen from the results of Table 13, the viscosity index improver composition of the present invention has a high viscosity index improving effect when added to a lubricating oil composition, and is extremely excellent as a viscosity index improver composition.

[0409] Industrial Applicability

[0410] The viscosity index improver composition of the present invention does not easily generate gel, and the lubricating oil composition containing the viscosity index improver composition of the present invention can be suitably used in gear oil (differential oil and industrial gear oil, etc.), MTF, transmission oil [ATF, DCTF and belt CVTF, etc.], traction oil (annular CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (hydraulic oil for construction machinery and industrial hydraulic oil, etc.) and engine oil (for gasoline engines and diesel engines), and is particularly suitable as a lubricating oil composition for internal combustion engines, especially a lubricating oil composition for hybrid vehicles.

Claims

1. A viscosity index improver composition comprising a copolymer (A) and a 100° C. kinematic viscosity of 4.0 mm 2 / s or less, the copolymer (A) comprising a polyolefin monomer (a) represented by the following general formula (1) and an alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms (b) as essential constituent monomers, wherein: Based on the total weight of the monomers constituting the copolymer (A), the content of the monomer (a) is 1 wt% to 20 wt%, the content of the (meth)acrylic acid alkyl ester (b) is 45 wt% to 85 wt%, [Chemistry 1] In the general formula (1), R 1 is a hydrogen atom or a methyl group; -X 1 - is -O-, -O(AO) m - or -NH-, A is an alkylene group having 2 to 4 carbon atoms, m is an integer of 1 to 10, and when m is 2 or more, A is the same or different; R 2 It is a residue obtained by removing one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit; p is a number of 0 or 1.

2. The viscosity index improver composition according to claim 1, wherein The ratio of the weight of the copolymer (A) to the weight of the Fischer-Tropsch derived base oil (B) {(A) / (B)} contained in the viscosity index improver composition is 0.05 to 10.

3. The viscosity index improver composition according to claim 1 or 2, wherein The solubility parameter of the copolymer (A) is 8.0 (cal / cm 3 ) 1 / 2 ~10.0(cal / cm 3 ) 1 / 2 .

4. The viscosity index improver composition according to claim 1 or 2, wherein The copolymer (A) is a copolymer containing a (meth)acryloyl monomer (c) having an alkyl group having 9 to 36 carbon atoms as a constituent monomer.

5. The viscosity index improver composition according to claim 4, wherein The copolymer (A) is a copolymer containing a monomer (d) represented by the following general formula (2) as a constituent monomer, [Chemistry 2] 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; R 5 is an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 20 carbon atoms; q is an integer of 1 to 20, and when q is 2 or more, R 4 Same or different.

6. The viscosity index improver composition according to claim 5, wherein The copolymer (A) contains, as constituent monomers, 1 to 53% by weight of the monomer (c) and 1 to 35% by weight of the monomer (d) based on the total weight of the monomers constituting (A).

7. The viscosity index improver composition according to claim 1 or 2, wherein The weight average molecular weight of the copolymer (A) is 5,000 to 2,000,000.

8. The viscosity index improver composition according to claim 1 or 2, wherein The present invention further contains a base oil of Group I to V of API classification other than the Fischer-Tropsch derived base oil (B).

9. A lubricating oil composition comprising the viscosity index improver composition according to claim 1 or 2, and at least one additive selected from the group consisting of a detergent, a dispersant, an antioxidant, an oiliness improver, a pour point depressant, a friction and wear modifier, an extreme pressure agent, a defoamer, an anti-emulsifier, a metal deactivator and a corrosion inhibitor.

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