Lubricating oil composition for automobile transmissions

Abstract

To provide a lubricant composition for an automobile transmission capable of improving fuel economy performance, that has an excellent temperature-viscosity property, that is, an oil film retention property at high temperatures and a low-temperature viscosity property, and maintains performance continuously during long-term use.SOLUTION: A lubricant composition for an automobile transmission having a kinematic viscosity at 100°C of 4 to 10 mm2 / s comprises: a lubricant base oil consisting of a mineral oil having a kinematic viscosity at 100°C of 2 to 8 mm2 / s, a viscosity index of 90 or more, and a pour point of 0°C or less, and / or, a synthetic oil having a kinematic viscosity at 100°C of 2 to 8 mm2 / s, a viscosity index of 110 or more, and a pour point of -30°C or less; and an ethylene-α-olefin co-polymer having ethylene mole content in the range of 30 to 70 mol %, rotational viscosity at 150°C of 200 to 8,000 mPa*s, Hazen chromaticity of 30 or less, molecular weight distribution of (Mw / Mn) of 2.5 or less, and a B value of 1.1 or greater.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil composition for automobile transmissions. [Background technology]

[0002] Lubricating oils such as gear oils, transmission oils, hydraulic oils, and greases are required to provide various performance characteristics, including wear resistance, heat resistance, sludge resistance, lubricant consumption characteristics, and fuel economy, in addition to performance requirements such as heat dissipation and protection of internal combustion engines and machine tools. Furthermore, in recent years, the performance requirements have become increasingly sophisticated due to the increasing performance, power output, and harsher operating conditions of the internal combustion engines and industrial machinery used. In particular, while the operating environment of lubricating oils has become more severe recently, there is a trend toward longer life due to environmental concerns. This has led to demands for improved heat resistance and oxidation stability, as well as suppression of viscosity reduction due to shear stress from engines and machines, i.e., improved shear stability of lubricating oils. On the other hand, in order to improve the energy conversion efficiency of engines or ensure good lubrication of engines in extremely low temperature environments, temperature-viscosity characteristics, such as maintaining a lubricating oil film at high temperatures and maintaining better fluidity at low temperatures, are becoming increasingly important. As one index of the temperature viscosity characteristics described here, the temperature viscosity characteristics can be quantified by a viscosity index calculated by the method described in JIS K2283, and a higher viscosity index indicates better temperature viscosity characteristics.

[0003] Therefore, lubricating oils are required to have excellent heat resistance, oxidation stability, and shear stability, as well as good temperature-viscosity characteristics.

[0004] In particular, transmission fluids used in automobiles are being required to have better temperature viscosity characteristics than ever before, as well as high fluidity at extremely low temperatures such as -40°C, i.e., excellent low-temperature viscosity characteristics. These viscosity characteristics are directly linked to the fuel efficiency of automobiles, and the demand for improved performance has grown since the adoption of the Kyoto Protocol in 1997, as governments around the world have recently established carbon dioxide emission and fuel efficiency regulations for passenger cars, or set future targets.

[0005] Based on this, in order to achieve fuel efficiency targets, the engine components in automobile transmissions have been downsized to improve fuel efficiency, and the amount of lubricating oil used has been reduced. As a result, the load on the lubricating oil has increased, and there is a demand for even longer lubricating oil life. In addition, especially for automobile transmission oils for standard automobiles, there has been a demand in recent years for transmission oils to be able to be replaced without replacement, so further extending the life of lubricating oils has become an urgent issue.

[0006] Automotive transmissions include manual transmissions, automatic transmissions, continuously variable transmissions, and dual-clutch transmissions. In all transmissions, transmission fluids are subjected to shear stress from gears or metal belts. This causes the molecules of the base material used in the lubricant to break down over time, resulting in a decrease in lubricant viscosity. This decrease in lubricant viscosity can lead to gear-to-gear and metal-to-metal contact, causing significant gear damage. Therefore, it is necessary to anticipate viscosity decline over time and increase the initial viscosity of the lubricant at the time of manufacturing to ensure optimal lubrication after use and deterioration. Naturally, if the base material used in the lubricant has excellent shear stability, i.e., a long lifespan, there is no need to increase the initial viscosity. This reduces the agitation resistance of the lubricant against the gears, thereby improving fuel economy.

[0007] Furthermore, in recent years, measures to improve fuel economy have been implemented to reduce the viscosity of transmission fluids, thereby reducing the stirring resistance of lubricating oils. Not only does increasing the initial viscosity to prepare for viscosity reduction contradict this measure, but lowering viscosity also increases the risk of metal-to-metal contact in gears, so there is a demand for materials with extremely high shear stability that do not cause viscosity reduction.

[0008] The Society of Automobile Engineers (SAE) specifies that automotive gear oils must "stay-in-grade" after the shear test specified in CRC L-45-T-93, in accordance with its viscosity standard J306. However, in recent years, the risk of metal-to-metal contact has increased due to lower viscosity transmission oils. This has led to a need to specify a minimum viscosity after shear testing to prevent insufficient lubrication performance after transmission use and deterioration.

[0009] Furthermore, the high oil film retention ability of the base material used in the transmission fluid is also an important performance factor for the low-viscosity transmission fluids mentioned above, because the higher the oil film retention ability of the base material, the lower the viscosity can be, which in turn leads to improved fuel economy.

[0010] Furthermore, if the temperature viscosity characteristics are excellent, i.e., if the temperature dependency of the lubricating oil viscosity is low, viscosity increase can be suppressed even in low temperature environments, resulting in relatively lower gear resistance due to the lubricating oil compared to conventional technology, thereby improving fuel efficiency.

[0011] Conventionally, lubricating oil compositions have been known that use methacrylate copolymers, methacrylic acid ester copolymers, or the like as viscosity modifiers or viscosity index improvers to improve the temperature viscosity characteristics of lubricating oils as a measure to improve fuel economy, as exemplified in Patent Documents 1 to 4. Such copolymers are collectively called polymethacrylates.

[0012] It has been known that the shear stability of a lubricating oil composition depends on the molecular weight of the components it contains. That is, lubricating oil compositions containing components with higher molecular weights are more likely to experience viscosity loss due to shear stress, and this viscosity loss rate correlates with the molecular weight of the components it contains.

[0013] On the other hand, the temperature viscosity characteristics and low-temperature viscosity characteristics of a lubricating oil composition are improved by including a higher amount of high-molecular-weight components. That is, the viscosity modifier or viscosity index improver used in a lubricating oil composition has a trade-off relationship in that as the molecular weight increases, the temperature viscosity characteristics improve, but the shear stability decreases. In this regard, there is room for improvement from the perspective of achieving both shear stability and temperature viscosity characteristics.

[0014] In particular, dual-clutch transmission oils that use wet clutches have a gear mechanism similar to that of manual transmission oils, which means that the transmission oil is subjected to high shear stress.However, because the transmission oil uses wet clutches, the filling volume is significantly greater than that of manual transmissions, and the stirring resistance of the transmission oil has a greater effect, so it is necessary to achieve both very high shear stability and excellent temperature viscosity characteristics.

[0015] Patent Document 5 discloses a lubricating oil composition containing a specific lubricating base oil and a specific ethylene-α-olefin copolymer, which has both of these properties and is suitable for use in automobile transmissions.

[0016] Patent Document 6 also describes that a lubricating oil composition containing an ethylene-α-olefin (co)polymer produced using a specific catalyst and satisfying specific conditions has extremely high shear stability, as well as well-balanced high-level viscosity characteristics and low-temperature viscosity characteristics, and also has excellent thermal oxidation resistance, making it suitable for use as an automobile transmission oil. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Japanese Patent Application Publication No. 8-53683 [Patent Document 2] Patent No. 4414123 [Patent Document 3] Patent No. 3816847 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-256665 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-69405 [Patent Document 6] International Publication No. 2020 / 194547 Summary of the Invention [Problem to be solved by the invention]

[0018] In view of the problems in the prior art, the problem that the present invention aims to solve is to provide a lubricating oil composition for automobile transmissions that has extremely superior temperature viscosity characteristics compared to conventional lubricating oils containing the same lubricating base oil, i.e., that has both oil film retention at high temperatures and low temperature viscosity characteristics, and that is capable of maintaining lubricating oil performance over long periods of use, i.e., that has excellent shear stability and is capable of improving fuel economy performance. [Means for solving the problem]

[0019] The present inventors have found that a lubricating oil composition that satisfies certain conditions can solve the above problems, and have completed the present invention. Specific embodiments of the present invention include the following.

[0020] [1] A lubricating oil base oil comprising (A) a mineral oil having the following characteristics (A1) to (A3) and / or (B) a synthetic oil having the following characteristics (B1) to (B3), and (C) an ethylene-α-olefin copolymer having the following characteristics (C1) to (C5), and having a kinematic viscosity at 100°C of 4 to 10 mm 2 A lubricating oil composition for automobile transmissions, comprising: (A1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s (A2) Viscosity index is 90 or more (A3) The pour point is 0°C or less (B1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s (B2) Viscosity index is 110 or more (B3) The pour point is -30°C or less (C1) The ethylene molar content is in the range of 30 to 70 mol%. (C2) Rotational viscosity at 150°C is 200 to 8,000 mPa·s (C3) Hazen color scale is 30 or less (C4) The molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) and calculated as polystyrene is 2.5 or less. (C5) The following formula [1]

number

[0021] [2] The lubricating oil composition for automobile transmissions according to [1] above, wherein the ethylene molar content of the ethylene-α-olefin copolymer (C) is in the range of 40 to 60 mol %.

[0022] [3] The lubricating oil composition for automobile transmissions according to [1] or [2] above, wherein the rotational viscosity of the ethylene-α-olefin copolymer (C) at 150°C is 1,000 to 5,000 mPa·s.

[0023] [4] The lubricating oil composition for automobile transmissions according to any one of [1] to [3] above, wherein the α-olefin in the ethylene-α-olefin copolymer (C) is propylene. [5] The lubricating oil composition for automobile transmissions according to any one of [1] to [4] above, wherein the content of the ethylene-α-olefin copolymer (C) is 1 to 10 mass %. [Effects of the Invention]

[0024] The lubricating oil composition for automobile transmissions of the present invention has extremely superior temperature viscosity characteristics compared to conventional lubricating oils containing the same lubricating base oil, i.e., it has both oil film retention at high temperatures and low temperature viscosity characteristics, and can maintain its lubricating oil performance over long periods of use, i.e., it has excellent shear stability and can improve fuel economy performance. DETAILED DESCRIPTION OF THE INVENTION

[0025] The lubricating oil composition for automobile transmissions according to the present invention (hereinafter also simply referred to as "lubricating oil composition") will be described in detail below.

[0026] [Lubricant composition for automobile transmissions] The lubricating oil composition for automobile transmissions according to the present invention contains a lubricating base oil consisting of (A) a mineral oil and / or (B) a synthetic oil, and (C) an ethylene-α-olefin copolymer, and is characterized by having a kinematic viscosity and viscosity index at 100°C within specific ranges.

[0027] <(C) Ethylene-α-olefin copolymer> (C) The ethylene-α-olefin copolymer has the following characteristics (C1) to (C5). (C1) The ethylene molar content is in the range of 30 to 70 mol%.

[0028] The ethylene molar content of the ethylene-α-olefin copolymer (C) is usually 30 to 70 mol%, preferably 40 to 60 mol%, and particularly preferably 45 to 58 mol%. If the ethylene molar content is outside this range, crystallization occurs at low temperatures, the low-temperature viscosity increases, and the low-temperature viscosity characteristics of the lubricating oil composition deteriorate.

[0029] (C) The ethylene molar content of ethylene-α-olefin copolymer was determined according to the method described in "Polymer Analysis Handbook" (published by Asakura Publishing, pp. 163-170). 13 It is measured by C-NMR. It is also possible to measure the sample determined by this method as a known sample using Fourier transform infrared spectroscopy (FT-IR).

[0030] (C2) Rotational viscosity at 150°C is 200 to 8,000 mPa·s This rotational viscosity value is measured according to the method described in JIS Z8803. The rotational viscosity of the (C) ethylene-α-olefin copolymer at 150°C is 200 to 8,000 mPa·s, preferably 800 to 6,000 mPa·s, more preferably 1,000 to 5,000 mPa·s, even more preferably 1,200 to 4,500 mPa·s, and particularly preferably 1,500 to 4,000 mPa·s. If the (C) ethylene-α-olefin copolymer has a rotational viscosity at 150°C above the above range, the shear stability and heat resistance of the lubricating oil composition deteriorate, and it becomes difficult to dissolve the copolymer uniformly in the lubricating base oil. If the rotational viscosity is below the above range, low-temperature fluidity deteriorates, resulting in a significant deterioration in fuel economy during startup in low-temperature environments. In addition, when producing the lubricating oil composition, the fluidity of the (C) ethylene-α-olefin copolymer increases, making stable metering difficult and significantly reducing weighing accuracy, which is undesirable.

[0031] (C3) Hazen color scale is 30 or less This Hazen color index value is measured by the method described in JIS K 0071. The Hazen color index of the (C) ethylene-α-olefin copolymer is not more than 30, preferably not more than 25, and more preferably not more than 20. If the (C) ethylene-α-olefin copolymer has a Hazen color index exceeding this range, it means that there are excessive oxygen-containing functional groups in the molecules of the (C) ethylene-α-olefin copolymer, and the heat resistance of the resulting lubricating oil composition will be impaired.

[0032] (C4) Molecular weight distribution is 2.5 or less The molecular weight distribution of the (C) ethylene-α-olefin copolymer is measured by gel permeation chromatography (GPC) according to the method described below, and calculated as the ratio (Mw / Mn) of the weight average molecular weight (Mw) obtained in terms of standard polystyrene to the number average molecular weight (Mn). This Mw / Mn is 2.5 or less, preferably 2.3 or less, and more preferably 2.2 or less. A molecular weight distribution outside this range means that the composition contains a large amount of low molecular weight and high molecular weight components. If the composition contains a large amount of low molecular weight components, the amount of easily volatile components increases, which increases the evaporation loss in the lubricating oil composition and reduces the thickening effect. If the composition contains a large amount of high molecular weight components, the shear stability and heat resistance stability of the lubricating oil composition deteriorate.

[0033] (C5) B value is 1.1 or more The B value of the ethylene-α-olefin copolymer (C), represented by the following formula [1], is 1.1 or more, and preferably 1.2 or more.

[0034]

number

[0035] The B value is an index showing the randomness of the copolymerization monomer sequence distribution in the copolymer, and is expressed by P in the above formula [1]. E , P O and P OE teeth, 13The B value can be determined by measuring the C-NMR spectrum and based on known literature such as reports by J.C. Randall [Macromolecules, 15, 353 (1982)] and J. Ray [Macromolecules, 10, 773 (1977)], "Polymer Analysis Handbook" (published by Asakura Publishing, pp. 163-170). The larger the B value, the fewer the chain structures of ethylene and α-olefins, the more uniform the distribution of ethylene and α-olefins, and the narrower the composition distribution of the copolymer. As a result, the larger the B value, the lower the pour point of the (C) ethylene-α-olefin copolymer, and the better the low-temperature viscosity characteristics of the lubricating oil composition. Specific conditions for measuring the B value are described in the Examples.

[0036] The ethylene-α-olefin copolymer (C) preferably further has at least one of the following characteristics (C6) and (C7):

[0037] (C6) Weight average molecular weight is 10,000 to 50,000 The weight-average molecular weight (Mw) of the (C) ethylene-α-olefin copolymer is measured by gel permeation chromatography (GPC) according to the method described below, and is calculated in terms of standard polystyrene. This weight-average molecular weight (Mw) is preferably 12,000 to 40,000, more preferably 15,000 to 35,000, and even more preferably 20,000 to 30,000. When the (C) ethylene-α-olefin copolymer has a weight-average molecular weight (Mw) of 10,000 or more, the lubricating oil composition has a low volatile content, resulting in low evaporation loss and excellent thickening effect and temperature-viscosity characteristics. When the (C) ethylene-α-olefin copolymer has a weight-average molecular weight (Mw) of 50,000 or less, the lubricating oil composition has a low pour point, excellent shear stability and heat resistance, and it is easy to uniformly dissolve the (C) ethylene-α-olefin copolymer in the lubricating base oil.

[0038] (C7) No melting point is observed It is preferable that the (C) ethylene-α-olefin copolymer has no observable melting point in differential scanning calorimetry (DSC). Here, "no observable melting point (Tm)" means that the heat of fusion (ΔH) (unit: J / g) measured by differential scanning calorimetry (DSC) is substantially not measurable. "Substantially no measurable heat of fusion (ΔH)" means that no peak is observed in DSC measurement, or the observed heat of fusion is 1 J / g or less. The melting point (Tm) and heat of fusion (ΔH) of the (C) ethylene-α-olefin copolymer are determined by analyzing the DSC curve with reference to JIS K7121 after measuring with a differential scanning calorimeter (DSC) and cooling to -100°C and then heating to 150°C at a heating rate of 10°C / min. If no melting point is observed, no crystalline components are formed at low temperatures, suppressing the increase in low-temperature viscosity, and the lubricating oil composition has excellent low-temperature viscosity characteristics.

[0039] Examples of the α-olefin used in the (C) ethylene-α-olefin copolymer include linear or branched α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and vinylcyclohexane. The α-olefin is preferably a linear or branched α-olefin having 3 to 10 carbon atoms, more preferably propylene, 1-butene, 1-hexene, and 1-octene. From the viewpoint of the shear stability of the lubricating oil using the resulting copolymer, propylene is most preferred. These α-olefins may be used alone or in combination.

[0040] The polymerization can also be carried out in the presence of at least one other monomer selected from a polar group-containing monomer, an aromatic vinyl compound, and a cyclic olefin in the reaction system. The other monomer can be used in an amount of, for example, 20 parts by mass or less, preferably 10 parts by mass or less, per 100 parts by mass of the total of ethylene and the α-olefin having 3 to 20 carbon atoms.

[0041] Examples of polar group-containing monomers include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, and maleic anhydride, and metal salts thereof such as sodium salts; α,β-unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate, and ethyl methacrylate; vinyl esters such as vinyl acetate and vinyl propionate; and unsaturated glycidyls such as glycidyl acrylate and glycidyl methacrylate.

[0042] Examples of aromatic vinyl compounds include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, methoxystyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylbenzyl acetate, hydroxystyrene, p-chlorostyrene, divinylbenzene, α-methylstyrene, and allylbenzene.

[0043] Examples of the cyclic olefin include cyclic olefins having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, and tetracyclododecene.

[0044] The method for producing the ethylene-α-olefin copolymer (C) in the present invention is not particularly limited, but examples include methods using a vanadium catalyst comprising a vanadium compound and an organoaluminum compound, as described in Japanese Patent Publication Nos. 2-1163 and 2-7998. Alternatively, methods for producing copolymers with high polymerization activity may include methods using a catalyst system comprising a metallocene compound such as zirconocene and an organoaluminum oxy compound (aluminoxane), as described in Japanese Patent Laid-Open Publication Nos. 61-221207, 7-121969, and Japanese Patent Publication No. 2796376. This method is preferred because it reduces the chlorine content of the resulting copolymer and the 2,1-insertion of propylene. Compared to methods using metallocene catalysts, methods using vanadium catalysts require a larger amount of chlorine compound as a cocatalyst, which may result in trace amounts of chlorine remaining in the resulting ethylene-α-olefin copolymer (C).

[0045] On the other hand, in the method using a metallocene catalyst, substantially no chlorine remains, so there is no need to consider the possibility of corrosion of metal parts in machines, etc. The chlorine content is preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 20 ppm or less, and particularly preferably 5 ppm or less. The chlorine content can be quantified by various known methods. Specific measurement methods in the present invention are as described in the Examples.

[0046] Furthermore, the reduction in 2,1-insertion of propylene makes it possible to further reduce the ethylene chains in the copolymer molecule, and suppress the intramolecular crystallinity of ethylene, thereby improving the viscosity-temperature characteristics and low-temperature viscosity characteristics of the lubricating oil composition. The amount of 2,1-insertion of propylene can be determined according to the method described in JP-A-7-145212. 13 It is determined by C-NMR measurement and analysis, and is preferably less than 1%, further preferably 0 to 0.5%, and even more preferably 0 to 0.1%. It is particularly preferable that no peak is observed in the range of 15.0 to 17.5 ppm.

[0047] In particular, by using the following method, it is possible to obtain (C) an ethylene-α-olefin copolymer having a good balance of performance in terms of molecular weight control, molecular weight distribution, amorphousness, and B value.

[0048] The ethylene-α-olefin copolymer (C) of the present invention can be produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst containing a bridged metallocene compound (a) represented by the following general formula [I] and at least one compound (b) selected from the group consisting of an organometallic compound (b-1), an organoaluminum oxy compound (b-2), and a compound (b-3) that reacts with the bridged metallocene compound (a) to form an ion pair.

[0049] [ka]

[0050] <Bridged metallocene compounds> The bridged metallocene compound (a) is represented by the above formula [I]. 1 ~R 14 , Q, n and j are explained below.

[0051] (Y, M, R 1 ~R 14 , Q, n and j) Y is a Group 14 atom, examples of which include a carbon atom, a silicon atom, a germanium atom and a tin atom, and is preferably a carbon atom or a silicon atom, and more preferably a carbon atom.

[0052] M is a titanium atom, a zirconium atom or a hafnium atom, and is preferably a zirconium atom. R 1 ~R 12 are atoms or substituents selected from the group consisting of hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups, and may be the same or different.1 From R 12 Adjacent substituents up to may be bonded to each other to form a ring, or may not be bonded to each other.

[0053] Here, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, a chain unsaturated hydrocarbon group having 2 to 20 carbon atoms, a cyclic unsaturated hydrocarbon group having 3 to 20 carbon atoms, an alkylene group having 1 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms.

[0054] Examples of alkyl groups having 1 to 20 carbon atoms include linear saturated hydrocarbon groups such as methyl, ethyl, n-propyl, allyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decanyl, and branched saturated hydrocarbon groups such as isopropyl, isobutyl, s-butyl, t-butyl, t-amyl, neopentyl, 3-methylpentyl, 1,1-diethylpropyl, 1,1-dimethylbutyl, 1-methyl-1-propylbutyl, 1,1-propylbutyl, 1,1-dimethyl-2-methylpropyl, 1-methyl-1-isopropyl-2-methylpropyl, and cyclopropylmethyl. The number of carbon atoms in the alkyl group is preferably 1 to 6.

[0055] Examples of cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms include cyclic saturated hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornenyl, 1-adamantyl, and 2-adamantyl, and groups in which hydrogen atoms of cyclic saturated hydrocarbon groups are replaced with hydrocarbon groups having 1 to 17 carbon atoms such as 3-methylcyclopentyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 4-cyclohexylcyclohexyl, and 4-phenylcyclohexyl. The number of carbon atoms in the cyclic saturated hydrocarbon group is preferably 5 to 11.

[0056] Examples of the chain unsaturated hydrocarbon group having 2 to 20 carbon atoms include alkenyl groups such as ethenyl group (vinyl group), 1-propenyl group, 2-propenyl group (allyl group), 1-methylethenyl group (isopropenyl group), etc., and alkynyl groups such as ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), etc. The number of carbon atoms in the chain unsaturated hydrocarbon group is preferably 2 to 4.

[0057] Examples of cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms include cyclic unsaturated hydrocarbon groups such as cyclopentadienyl, norbornyl, phenyl, naphthyl, indenyl, azulenyl, phenanthryl, and anthracenyl; groups in which hydrogen atoms of cyclic unsaturated hydrocarbon groups are replaced with hydrocarbon groups having 1 to 15 carbon atoms, such as 3-methylphenyl (m-tolyl), 4-methylphenyl (p-tolyl), 4-ethylphenyl, 4-t-butylphenyl, 4-cyclohexylphenyl, biphenylyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, and 2,4,6-trimethylphenyl (mesityl); and groups in which hydrogen atoms of linear or branched saturated hydrocarbon groups are replaced with cyclic saturated or unsaturated hydrocarbon groups having 3 to 19 carbon atoms, such as benzyl and cumyl. The number of carbon atoms in the cyclic unsaturated hydrocarbon group is preferably 6 to 10.

[0058] Examples of alkylene groups having 1 to 20 carbon atoms include methylene, ethylene, dimethylmethylene (isopropylidene), ethylmethylene, methylethylene, n-propylene, etc. The alkylene group preferably has 1 to 6 carbon atoms.

[0059] Examples of the arylene group having 6 to 20 carbon atoms include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4'-biphenylylene group, etc. The arylene group preferably has 6 to 12 carbon atoms.

[0060] Examples of silicon-containing groups include alkylsilyl groups such as trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, and triisopropylsilyl, which are hydrocarbon groups having 1 to 20 carbon atoms and in which a carbon atom has been replaced with a silicon atom; arylsilyl groups such as dimethylphenylsilyl, methyldiphenylsilyl, and t-butyldiphenylsilyl; pentamethyldisilanyl; and trimethylsilylmethyl. The alkylsilyl group preferably has 1 to 10 carbon atoms, and the arylsilyl group preferably has 6 to 18 carbon atoms.

[0061] Examples of the nitrogen-containing group include an amino group, a group in which the =CH- structural unit in the above-mentioned hydrocarbon group or silicon-containing group having 1 to 20 carbon atoms is replaced with a nitrogen atom, a group in which the -CH2- structural unit is replaced with a nitrogen atom bonded to a hydrocarbon group having 1 to 20 carbon atoms, or a group in which the -CH3 structural unit is replaced with a nitrogen atom or a nitrile group bonded to a hydrocarbon group having 1 to 20 carbon atoms, such as a dimethylamino group, diethylamino group, N-morpholinyl group, dimethylaminomethyl group, cyano group, pyrrolidinyl group, piperidinyl group, pyridinyl group, N-morpholinyl group, and nitro group. Preferred nitrogen-containing groups are dimethylamino group and N-morpholinyl group.

[0062] Examples of the oxygen-containing group include a hydroxyl group, a group in which the -CH2- structural unit in the above-mentioned hydrocarbon group having 1 to 20 carbon atoms, silicon-containing group or nitrogen-containing group is replaced with an oxygen atom or a carbonyl group, or a group in which the -CH3 structural unit is replaced with an oxygen atom bonded to a hydrocarbon group having 1 to 20 carbon atoms, such as a methoxy group, ethoxy group, t-butoxy group, phenoxy group, trimethylsiloxy group, methoxyethoxy group, hydroxymethyl group, methoxymethyl group, ethoxymethyl group, t-butoxymethyl group, 1-hydroxyethyl ... Examples of oxygen-containing groups include 1-methoxyethyl group, 1-ethoxyethyl group, 2-hydroxyethyl group, 2-methoxyethyl group, 2-ethoxyethyl group, n-2-oxabutylene group, n-2-oxapentylene group, n-3-oxapentylene group, aldehyde group, acetyl group, propionyl group, benzoyl group, trimethylsilylcarbonyl group, carbamoyl group, methylaminocarbonyl group, carboxy group, methoxycarbonyl group, carboxymethyl group, ethoxycarboxymethyl group, carbamoylmethyl group, furanyl group, and pyranyl group. As the oxygen-containing group, a methoxy group is preferred.

[0063] Examples of halogen atoms include fluorine, chlorine, bromine, iodine, etc., which are elements of Group 17. Examples of halogen-containing groups include trifluoromethyl, tribromomethyl, pentafluoroethyl, and pentafluorophenyl groups, which are groups in which a hydrogen atom in the above-mentioned hydrocarbon group, silicon-containing group, nitrogen-containing group, or oxygen-containing group having 1 to 20 carbon atoms is substituted with a halogen atom.

[0064] Q may be the same or different and may be selected from a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an anionic ligand, and a neutral ligand capable of coordinating with a lone electron pair. Details of the halogen atom and the hydrocarbon group having 1 to 20 carbon atoms are as described above. When Q is a halogen atom, it is preferably a chlorine atom. When Q is a hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group preferably has 1 to 7 carbon atoms.

[0065] Examples of the anionic ligand include alkoxy groups such as methoxy, t-butoxy, and phenoxy groups, carboxylate groups such as acetate and benzoate, and sulfonate groups such as mesylate and tosylate.

[0066] Examples of neutral ligands capable of coordinating with lone electron pairs include organic phosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine, and diphenylmethylphosphine, and ether compounds such as tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxyethane.

[0067] j is an integer of 1 to 4, and is preferably 2. n is an integer of 1 to 4, preferably 1 or 2, and more preferably 1. R 13 and R 14 are atoms or substituents selected from the group consisting of hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, aryl groups, substituted aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms, and halogen-containing groups, and may be the same or different. 13 and R 14 may be bonded to each other to form a ring, or may not be bonded to each other.

[0068] Details of the hydrocarbon group having 1 to 20 carbon atoms, the silicon-containing group, the nitrogen-containing group, the oxygen-containing group, the halogen atom and the halogen-containing group are as described above. Examples of aryl groups partially overlap with the examples of the cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms described above, but include substituents derived from aromatic compounds, such as phenyl, 1-naphthyl, 2-naphthyl, anthracenyl, phenanthrenyl, tetracenyl, chrysenyl, pyrenyl, indenyl, azulenyl, pyrrolyl, pyridyl, furanyl, and thiophenyl. Preferred aryl groups are phenyl and 2-naphthyl.

[0069] Examples of the aromatic compounds include aromatic hydrocarbons and heterocyclic aromatic compounds such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, pyrene, indene, azulene, pyrrole, pyridine, furan, and thiophene.

[0070] The substituted aryl group partially overlaps with the examples of the cyclic unsaturated hydrocarbon group having 3 to 20 carbon atoms described above, but examples include groups in which one or more hydrogen atoms of the aryl group are substituted with at least one substituent selected from the group consisting of hydrocarbon groups having 1 to 20 carbon atoms, aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms, and halogen-containing groups. Specific examples include a 3-methylphenyl group (m-tolyl group), a 4-methylphenyl group (p-tolyl group), a 3-ethylphenyl group, a 4-ethylphenyl group, a 3,4-dimethylphenyl group, a 3,5-dimethylphenyl group, a biphenylyl group, a 4-(trimethylsilyl)phenyl group, a 4-aphenyl group, a 4-phenylsilyl ... Examples include an aminophenyl group, a 4-(dimethylamino)phenyl group, a 4-(diethylamino)phenyl group, a 4-morpholinylphenyl group, a 4-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-phenoxyphenyl group, a 3,4-dimethoxyphenyl group, a 3,5-dimethoxyphenyl group, a 3-methyl-4-methoxyphenyl group, a 3,5-dimethyl-4-methoxyphenyl group, a 3-(trifluoromethyl)phenyl group, a 4-(trifluoromethyl)phenyl group, a 3-chlorophenyl group, a 4-chlorophenyl group, a 3-fluorophenyl group, a 4-fluorophenyl group, a 5-methylnaphthyl group, and a 2-(6-methyl)pyridyl group.

[0071] In the bridged metallocene compound (a) represented by the above formula [I], n is preferably 1. Such a bridged metallocene compound (hereinafter also referred to as "bridged metallocene compound (a-1)") is represented by the following general formula [II].

[0072] [ka] In formula [II], Y, M, R 1 ~R 14The definitions of Q and j are as described above.

[0073] The bridged metallocene compound (a-1) has an advantage that the production process is simpler and the production cost is reduced compared to the compound in the above formula [I] where n is an integer of 2 to 4, and therefore the use of this bridged metallocene compound (a-1) has the advantage of reducing the production cost of the ethylene-α-olefin copolymer (C).

[0074] In the bridged metallocene compound (a-1) represented by the above formula [II], R 1 , R 2 , R 3 and R 4 are preferably all hydrogen atoms. Such a bridged metallocene compound (hereinafter also referred to as "bridged metallocene compound (a-2)") is represented by the following general formula [III].

[0075] [ka] In formula [III], Y, M, R 5 ~R 14 The definitions of Q and j are as described above.

[0076] The bridged metallocene compound (a-2) is a metallocene compound represented by the formula [I] 1 , R 2 , R 3 and R 4and (b) are substituted with a substituent other than a hydrogen atom, the production process is simplified and the production cost is reduced, and as a result, the use of this bridged metallocene compound (a-2) has the advantage of reducing the production cost of the ethylene-α-olefin copolymer (C). Furthermore, although it is generally known that high-temperature polymerization reduces the randomness of the ethylene-α-olefin copolymer (C), when ethylene and one or more monomers selected from α-olefins having 3 to 20 carbon atoms are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-2), the resulting ethylene-α-olefin copolymer (C) has the advantage of having high randomness even when polymerized at high temperature.

[0077] In the bridged metallocene compound (a-2) represented by the above formula [III], R 13 and R 14 Preferably, either one of R is an aryl group or a substituted aryl group. 13 and R 14 In comparison with the case where all of the substituents are other than an aryl group or a substituted aryl group, the resulting ethylene-α-olefin copolymer (C) has the advantage of having a smaller number of double bonds.

[0078] In the bridged metallocene compound (a-3), R 13 and R 14 It is more preferable that one of R is an aryl group or a substituted aryl group, and the other is an alkyl group having 1 to 20 carbon atoms. 13 and R 14 It is particularly preferred that one of R is an aryl group or a substituted aryl group, and the other is a methyl group. Such a bridged metallocene compound (hereinafter also referred to as "bridged metallocene compound (a-4)") can be obtained by 13 and R 14are all aryl groups or substituted aryl groups, the balance between the amount of double bonds in the resulting ethylene-α-olefin copolymer (C) and the polymerization activity is excellent, and the use of this bridged metallocene compound offers the advantage of reducing the production cost of the ethylene-α-olefin copolymer (C).

[0079] When polymerization is carried out under certain conditions of total pressure and temperature in a polymerization reactor, an increase in hydrogen partial pressure due to hydrogen introduction causes a decrease in the partial pressure of the olefin, which is the polymerization monomer, resulting in a problem of a decrease in the polymerization rate, particularly in the region where the hydrogen partial pressure is high. Because the allowable internal total pressure of a polymerization reactor is limited by its design, if excessive hydrogen introduction is required, particularly when producing a low-molecular-weight olefin polymer, the olefin partial pressure may decrease significantly, resulting in a decrease in polymerization activity. However, when the bridged metallocene compound (a-4) is used to produce the ethylene-α-olefin copolymer (C) of the present invention, the amount of hydrogen introduced into the polymerization reactor is reduced compared to when the bridged metallocene compound (a-3) is used, resulting in improved polymerization activity and reduced production costs for the ethylene-α-olefin copolymer (C).

[0080] In the bridged metallocene compound (a-4), R 6 and R 11 is preferably an alkyl group having 1 to 20 carbon atoms or an alkylene group having 1 to 20 carbon atoms, which may be bonded to adjacent substituents to form a ring. Such a bridged metallocene compound (hereinafter also referred to as "bridged metallocene compound (a-5)") can be obtained by the method described above. 6 and R 11 is substituted with a substituent other than an alkyl group having 1 to 20 carbon atoms or an alkylene group having 1 to 20 carbon atoms, the production process is simplified and the production cost is reduced. Consequently, the use of this bridged metallocene compound (a-5) offers the advantage of reducing the production cost of the ethylene-α-olefin copolymer (C).

[0081] In the bridged metallocene compound (a) represented by the general formula [I] above, the bridged metallocene compound (a-1) represented by the general formula [II] above, the bridged metallocene compound (a-2) represented by the general formula [III] above, and the bridged metallocene compounds (a-3), (a-4), and (a-5) above, M is more preferably a zirconium atom. When ethylene and one or more monomers selected from α-olefins having 3 to 20 carbon atoms are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound in which M is a zirconium atom, the polymerization activity is higher than when M is a titanium atom or a hafnium atom, and the production cost of the ethylene-α-olefin copolymer (C) is advantageously reduced.

[0082] Examples of such bridged metallocene compounds (a) include: [Dimethylmethylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [dimethylmethylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [dimethylmethylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [dimethylmethylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [dimethylmethylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [cyclohexylidene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [cyclohexylidene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [cyclohexylidene(η 5 -cyclopentadienyl)(η5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [cyclohexylidene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [cyclohexylidene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [diphenylmethylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [diphenylmethylene(η 5 -cyclopentadienyl)(η5-2,7-di-t-butylfluorenyl)]zirconium dichloride, diphenylmethylene(η 5 -2-methyl-4-t-butylcyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [diphenylmethylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [diphenylmethylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, diphenylmethylene{η 5 -(2-methyl-4-i-propylcyclopentadienyl)}(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [diphenylmethylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [methylphenylmethylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [methylphenylmethylene(η 5 -cyclopentadienyl)(η 5-2,7-di-t-butylfluorenyl)]zirconium dichloride, [methylphenylmethylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [methylphenylmethylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [methylphenylmethylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [methyl(3-methylphenyl)methylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [methyl(3-methylphenyl)methylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [methyl(3-methylphenyl)methylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [methyl(3-methylphenyl)methylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [methyl(3-methylphenyl)methylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [diphenylsilylene(η 5 -cyclopentadienyl)(η5-fluorenyl)]zirconium dichloride, [diphenylsilylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [diphenylsilylene(η 5 -cyclopentadienyl)(η 5-3,6-di-t-butylfluorenyl)]zirconium dichloride, [diphenylsilylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [diphenylsilylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [bis(3-methylphenyl)silylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [bis(3-methylphenyl)silylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [bis(3-methylphenyl)silylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [bis(3-methylphenyl)silylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [bis(3-methylphenyl)silylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [dicyclohexylsilylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [dicyclohexylsilylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [dicyclohexylsilylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [dicyclohexylsilylene(η 5 -cyclopentadienyl)(η 5-octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [dicyclohexylsilylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, [ethylene(η 5 -cyclopentadienyl)(η 5 -fluorenyl)]zirconium dichloride, [ethylene(η 5 -cyclopentadienyl)(η 5 -2,7-di-t-butylfluorenyl)]zirconium dichloride, [ethylene(η 5 -cyclopentadienyl)(η 5 -3,6-di-t-butylfluorenyl)]zirconium dichloride, [ethylene(η 5 -cyclopentadienyl)(η 5 -octamethyloctahydrodibenzofluorenyl)]zirconium dichloride, [ethylene(η 5 -cyclopentadienyl)(η 5 -tetramethyloctahydrodibenzofluorenyl)]zirconium dichloride, and the like.

[0083] Examples of the bridged metallocene compound (a) include compounds in which the zirconium atom of these compounds is replaced with a hafnium atom, or compounds in which the chloro ligand is replaced with a methyl group, but the bridged metallocene compound (a) is not limited to these examples. 5 -Tetramethyloctahydrodibenzofluorenyl is 4,4,7,7-tetramethyl-(5a,5b,11a,12,12a-η 5 )-1,2,3,4,7,8,9,10-octahydrodibenzo[b,H]fluorenyl group, η 5 -Octamethyloctahydrodibenzofluorenyl is 1,1,4,4,7,7,10,10-octamethyl-(5a,5b,11a,12,12a-η 5 )-1,2,3,4,7,8,9,10-octahydrodibenzo[b,H]fluorenyl group, respectively.

[0084] <Compound (b)> The polymerization catalyst used in the present invention contains at least one compound (b) selected from the group consisting of the above crosslinked metallocene compound (a), an organometallic compound (b-1), an organoaluminum oxy compound (b-2), and a compound (b-3) that reacts with the crosslinked metallocene compound (a) to form an ion pair.

[0085] As the organometallic compound (b-1), specifically, organometallic compounds of Groups 1, 2, 12, and 13 of the periodic table as described below are used.

[0086] (b-1a) General formula R a m Al(OR b ) n H p X q (In the formula, R a and R b may be the same or different from each other and represent a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, X represents a halogen atom, m is a number where 0 < m ≦ 3, n is a number where 0 ≦ n < 3, p is a number where 0 ≦ p < 3, q is a number where 0 ≦ q < 3, and m + n + p + q = 3) an organoaluminum compound represented by.

[0087] Such compounds include tri-n-alkylaluminums such as trimethylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-branched alkylaluminums such as triisopropylaluminum, triisobutylaluminum, trisec-butylaluminum, tri-t-butylaluminum, tri-2-methylbutylaluminum, tri- Trimethylhexylaluminum, tri-2-ethylhexylaluminum, etc., tricycloalkylaluminums such as tricyclohexylaluminum, tricyclooctylaluminum, etc., triarylaluminums such as triphenylaluminum, tri(4-methylphenyl)aluminum, etc., dialkylaluminum hydrides such as diisopropylaluminum hydride, diisobutylaluminum hydride, etc., general formula (i-C4H9)x Al y (C5H 10 ) z (wherein x, y, and z are positive numbers, and z≦2x), alkenyl aluminum such as isoprenyl aluminum, alkyl aluminum alkoxides such as isobutyl aluminum methoxide and isobutyl aluminum ethoxide, dialkyl aluminum alkoxides such as dimethyl aluminum methoxide, diethyl aluminum ethoxide, and dibutyl aluminum butoxide, alkyl aluminum sesquialkoxides such as ethyl aluminum sesquiethoxide and butyl aluminum sesquibutoxide, and compounds represented by the general formula R a 2.5 Al(ORb) 0.5 Examples of the alkylaluminum include partially alkoxylated alkylaluminums having an average composition represented by the formula (I) or (II), alkylaluminum aryloxides such as diethylaluminum phenoxide and diethylaluminum (2,6-di-t-butyl-4-methylphenoxide), dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide and diisobutylaluminum chloride, alkylaluminum sesquihalides such as ethylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide, partially halogenated alkylaluminums such as alkylaluminum dihalides such as ethylaluminum dichloride, dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride, alkylaluminum dihydrides such as ethylaluminum dihydride and propylaluminum dihydride, and other partially hydrogenated alkylaluminums, and partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxychloride, butylaluminum butoxychloride and ethylaluminum ethoxybromide. a m Al(ORb) n H p X qCompounds similar to the compound represented by the formula (1) can also be used, such as organoaluminum compounds in which two or more aluminum compounds are bonded via nitrogen atoms. Specific examples of such compounds include (C2H5)2AlN(C2H5)Al(C2H5)2.

[0088] (b-1b) General formula M 2 AlR a 4 (in the formula, M 2 indicates Li, Na, or K, and R a represents a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms.) A complex alkylation product of aluminum and a metal of Group 1 of the periodic table represented by the formula: Such compounds include LiAl(C2H5)4, LiAl(C7H 15 ) 4 can be exemplified.

[0089] (b-1c) General formula R a R b M 3 (In the formula, R a and R b may be the same or different and represent a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms; M 3 is Mg, Zn, or Cd. Dialkyl compounds of metals from Group 2 or 12 of the periodic table, represented by

[0090] As the organoaluminum oxy compound (b-2), a conventionally known aluminoxane can be used as it is. Specific examples include compounds represented by the following general formula [IV] and compounds represented by the following general formula [V].

[0091] [ka] In the formulas [IV] and [V], R represents a hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 2 or more.

[0092] In particular, methylaluminoxanes in which R is a methyl group and n is 3 or more, preferably 10 or more, are used. There is no problem if these aluminoxanes contain a small amount of an organoaluminum compound.

[0093] In the present invention, when copolymerization of ethylene with an α-olefin having 3 or more carbon atoms is carried out at high temperatures, benzene-insoluble organoaluminum oxy compounds such as those exemplified in JP-A-2-78687 can also be used. Also suitable are the organoaluminum oxy compounds described in JP-A-2-167305 and the aluminoxanes having two or more alkyl groups described in JP-A-2-24701 and JP-A-3-103407. The "benzene-insoluble organoaluminum oxy compounds" that may be used in the present invention are compounds that are insoluble or poorly soluble in benzene, with an Al atom solubility of typically 10% or less, preferably 5% or less, and particularly preferably 2% or less.

[0094] Further, examples of the organoaluminum oxy compound (b-2) include modified methylaluminoxanes represented by the following general formula [VI].

[0095] [ka] In formula [VI], R represents a hydrocarbon group having 1 to 10 carbon atoms, and m and n each independently represent an integer of 2 or more.

[0096] This modified methylaluminoxane is prepared using trimethylaluminum and an alkylaluminum other than trimethylaluminum. This compound is commonly referred to as MMAO. This MMAO can be prepared by the methods described in U.S. Patents 4,960,878 and 5,041,584. Tosoh Finechem Corporation and other companies also offer commercially available MMAO and TMAO, where R is an isobutyl group, prepared using trimethylaluminum and triisobutylaluminum. These MMAOs have improved solubility in various solvents and storage stability. Specifically, unlike the compounds represented by formulas [IV] and [V] above, which are insoluble or poorly soluble in benzene, they are soluble in aliphatic and alicyclic hydrocarbons.

[0097] Further, the organoaluminum oxy compound (b-2) may also include a boron-containing organoaluminum oxy compound represented by the following general formula [VII].

[0098] [ka] In formula [VII], R c R represents a hydrocarbon group having 1 to 10 carbon atoms. d may be the same or different and represent a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0099] Examples of the compound (b-3) that reacts with the bridged metallocene compound (a) to form an ion pair (hereinafter, sometimes abbreviated as "ionized ionic compound" or simply "ionic compound") include Lewis acids, ionic compounds, borane compounds, and carborane compounds described in JP-T-1-501950, JP-T-1-502036, JP-A-3-179005, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, and U.S. Patent No. 5,321,106. Further examples include heteropoly compounds and isopoly compounds.

[0100] The ionizing ionic compound preferably used in the present invention is a boron compound represented by the following general formula [VIII].

[0101] [ka] In formula [VIII], R e+ As for H + , carbenium cation, oxonium cation, ammonium cation, phosphonium cation, cycloheptyltrienyl cation, ferrocenium cation having a transition metal, etc. f ~R i may be the same or different and are substituents selected from hydrocarbon groups having 1 to 20 carbon atoms, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups, and are preferably substituted aryl groups.

[0102] Specific examples of the carbenium cation include trisubstituted carbenium cations such as triphenylcarbenium cation, tris(4-methylphenyl)carbenium cation, and tris(3,5-dimethylphenyl)carbenium cation.

[0103] Specific examples of the ammonium cation include trialkyl-substituted ammonium cations such as trimethylammonium cation, triethylammonium cation, tri(n-propyl)ammonium cation, triisopropylammonium cation, tri(n-butyl)ammonium cation, and triisobutylammonium cation; N,N-dialkylanilinium cations such as N,N-dimethylanilinium cation, N,N-diethylanilinium cation, and N,N-2,4,6-pentamethylanilinium cation; and dialkylammonium cations such as diisopropylammonium cation and dicyclohexylammonium cation.

[0104] Specific examples of the phosphonium cation include triarylphosphonium cations such as triphenylphosphonium cation, tris(4-methylphenyl)phosphonium cation, and tris(3,5-dimethylphenyl)phosphonium cation.

[0105] R e+ Of the above specific examples, preferred are carbenium cations and ammonium cations, with triphenylcarbenium cation, N,N-dimethylanilinium cation and N,N-diethylanilinium cation being particularly preferred.

[0106] Among the ionizable ionic compounds preferably used in the present invention, examples of compounds containing a carbenium cation include triphenylcarbenium tetraphenylborate, triphenylcarbenium tetrakis(pentafluorophenyl)borate, triphenylcarbenium tetrakis{3,5-di-(trifluoromethyl)phenyl}borate, tris(4-methylphenyl)carbenium tetrakis(pentafluorophenyl)borate, and tris(3,5-dimethylphenyl)carbenium tetrakis(pentafluorophenyl)borate.

[0107] Among the ionizable ionic compounds preferably used in the present invention, compounds containing a trialkyl-substituted ammonium cation include triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, trimethylammonium tetrakis(4-methylphenyl)borate, trimethylammonium tetrakis(2-methylphenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(2,4-dimethylphenyl)borate, tri(n-butyl)ammonium tetrakis(3,5-dimethylphenyl)borate, tri(n-butyl)ammonium tetrakis{4-(trifluoromethyl)phenyl}borate, tri Examples of the tetrakis include (n-butyl)ammonium tetrakis{3,5-di(trifluoromethyl)phenyl}borate, tri(n-butyl)ammonium tetrakis(2-methylphenyl)borate, dioctadecylmethylammonium tetraphenylborate, dioctadecylmethylammonium tetrakis(4-methylphenyl)borate, dioctadecylmethylammonium tetrakis(4-methylphenyl)borate, dioctadecylmethylammonium tetrakis(pentafluorophenyl)borate, dioctadecylmethylammonium tetrakis(2,4-dimethylphenyl)borate, dioctadecylmethylammonium tetrakis(3,5-dimethylphenyl)borate, dioctadecylmethylammonium tetrakis{4-(trifluoromethyl)phenyl}borate, dioctadecylmethylammonium tetrakis{3,5-di(trifluoromethyl)phenyl}borate, and dioctadecylmethylammonium.

[0108] Among the ionizable ionic compounds preferably used in the present invention, examples of compounds containing an N,N-dialkylanilinium cation include N,N-dimethylanilinium tetraphenylborate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis{3,5-di(trifluoromethyl)phenyl}borate, N,N-diethylanilinium tetraphenylborate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis{3,5-di(trifluoromethyl)phenyl}borate, N,N-2,4,6-pentamethylanilinium tetraphenylborate, and N,N-2,4,6-pentamethylanilinium tetrakis(pentafluorophenyl)borate.

[0109] Among the ionizable ionic compounds preferably used in the present invention, examples of compounds containing a dialkylammonium cation include di-n-propylammonium tetrakis(pentafluorophenyl)borate and dicyclohexylammonium tetraphenylborate.

[0110] In addition, the ionic compounds exemplified in JP-A-2004-51676 can also be used without any restrictions. The ionic compound (b-3) may be used alone or in combination of two or more.

[0111] As the organometallic compound (b-1), trimethylaluminum, triethylaluminum and triisobutylaluminum are preferred, as they are commercially available and therefore easily available, with triisobutylaluminum being particularly preferred because it is easy to handle.

[0112] As the organoaluminum oxy compound (b-2), methylaluminoxane, which is commercially available and therefore easily available, and MMAO prepared from trimethylaluminum and triisobutylaluminum are preferred. Among these, MMAO, which has improved solubility in various solvents and storage stability, is particularly preferred.

[0113] As the ionic compound (b-3), triphenylcarbenium tetrakis(pentafluorophenyl)borate and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate are preferred because they are easily available as commercial products and contribute greatly to improving polymerization activity.

[0114] As the compound (b), a combination of triisobutylaluminum and triphenylcarbenium tetrakis(pentafluorophenyl)borate, and a combination of triisobutylaluminum and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate are particularly preferred because they greatly improve the polymerization activity.

[0115] <Carrier (c)> In the present invention, a carrier (c) may be used as a constituent component of the olefin polymerization catalyst, if necessary.

[0116] The carrier (c) that may be used in the present invention is an inorganic or organic compound, which is a granular or particulate solid. Among these, the inorganic compound is preferably a porous oxide, an inorganic chloride, a clay, a clay mineral, or an ion-exchangeable layered compound.

[0117] Specific examples of porous oxides that can be used include SiO2, Al2O3, MgO, ZrO, TiO2, B2O3, CaO, ZnO, BaO, and ThO2, as well as composites or mixtures containing these, such as natural or synthetic zeolites, SiO2-MgO, SiO2-Al2O3, SiO2-TiO2, SiO2-V2O5, SiO2-Cr2O3, and SiO2-TiO2-MgO. Of these, those containing SiO2 and / or Al2O3 as the main components are preferred. While the properties of such porous oxides vary depending on the type and production method, the carriers preferably used in the present invention have a particle size of 0.5 to 300 μm, preferably 1.0 to 200 μm, and a specific surface area of ​​50 to 1000 m. 2 / g, preferably 100 to 700m 2 / g, and the pore volume is in the range of 0.3 to 3.0 cm 3 The carrier is calcined at 100 to 1000°C, preferably 150 to 700°C, as required, before use.

[0118] Examples of inorganic chlorides that can be used include MgCl, MgBr, MnCl, and MnBr. The inorganic chlorides may be used as they are, or may be pulverized using a ball mill or a vibration mill. Alternatively, the inorganic chlorides may be dissolved in a solvent such as alcohol and then precipitated into fine particles using a precipitating agent.

[0119] Clay is usually composed primarily of clay minerals. Ion-exchangeable layered compounds are compounds with a crystalline structure in which constituent planes are stacked parallel to one another with weak bonding forces, such as ionic bonds, and the ions contained therein are exchangeable. Most clay minerals are ion-exchangeable layered compounds. These clays, clay minerals, and ion-exchangeable layered compounds are not limited to natural products, and artificial synthetic compounds can also be used. Examples of clays, clay minerals, and ion-exchangeable layered compounds include clays, clay minerals, and ionic crystalline compounds with layered crystalline structures, such as hexagonal close-packed, antimony, CdCl2, and CdI2 types. Examples of such clays and clay minerals include kaolin, bentonite, kibushi clay, gairome clay, allophane, hisingerite, pyrophyllite, ummo group, montmorillonite group, vermiculite, ryokudeite group, palygorskite, kaolinite, nacrite, dickite, and halloysite. Examples of ion-exchange layered compounds include crystalline acid salts of polyvalent metals such as α-Zr(HAsO)·H0, α-Zr(HPO), α-Zr(KPO 3H0, α-Ti(HPO), α-Ti(HAsO)·H0, α-Sn(HPO), H0, γ-Zr(HPO), γ-Ti(HPO), and γ-Ti(NHPO). It is also preferable to chemically treat the clays and clay minerals used in the present invention. The chemical treatment can be any of surface treatments that remove impurities adhering to the surface, treatments that affect the crystalline structure of the clay, etc. Specific examples of chemical treatments include acid treatment, alkali treatment, salt treatment, and organic treatment.

[0120] The ion-exchangeable layered compound may be a layered compound in which the interlayer spacing is expanded by utilizing the ion exchange property and exchanging the exchangeable ions between the layers with other large, bulky ions. Such bulky ions act as supports supporting the layered structure and are usually called pillars. The introduction of another substance (guest compound) between the layers of a layered compound is called intercalation. Examples of guest compounds include cationic inorganic compounds such as TiCl4 and ZrCl4, metal alkoxides such as Ti(OR)4, Zr(OR)4, PO(OR)3, and B(OR)3 (where R is a hydrocarbon group, etc.), and [Al 13 O4(OH) 24 ] 7+ , [Zr(OH) 14 ] 2+ , [Fe3O(OCOCH3)6] + Examples of suitable pillars include metal hydroxide ions such as those mentioned above. These compounds can be used singly or in combination of two or more. When intercalating these compounds, polymers obtained by hydrolysis and polycondensation of metal alkoxides (R is a hydrocarbon group, for example) such as Si(OR)4, Al(OR)3, and Ge(OR)4, and colloidal inorganic compounds such as SiO2, can also be present. Examples of suitable pillars include oxides produced by intercalating the above metal hydroxide ions between layers and then dehydrating them with heat.

[0121] Among these, clay or clay minerals are preferred, and montmorillonite, vermiculite, pectolite, taeniolite, and synthetic mica are particularly preferred. Examples of organic compounds as carriers (c) include granular or particulate solids with particle sizes ranging from 0.5 to 300 μm. Specific examples include (co)polymers primarily composed of α-olefins having 2 to 14 carbon atoms, such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene, or (co)polymers primarily composed of vinylcyclohexane and styrene, as well as modified products thereof.

[0122] High-temperature polymerization is possible using a polymerization method using an olefin polymerization catalyst capable of producing a highly random ethylene-α-olefin copolymer (C). In other words, the use of this olefin polymerization catalyst can suppress the decrease in randomness of the ethylene-α-olefin copolymer (C) produced during high-temperature polymerization. In solution polymerization, the viscosity of the polymerization solution containing the produced ethylene-α-olefin copolymer (C) decreases at high temperatures, making it possible to increase the concentration of the ethylene-α-olefin copolymer (C) in the polymerization vessel compared to low-temperature polymerization, resulting in improved productivity per polymerization vessel. The copolymerization of ethylene and α-olefins in the present invention can be carried out using either a liquid-phase polymerization method such as solution polymerization or suspension polymerization (slurry polymerization) or a gas-phase polymerization method. However, solution polymerization is particularly preferred from the viewpoint of maximizing the benefits of the present invention.

[0123] The method of use and order of addition of each component of the olefin polymerization catalyst may be selected arbitrarily, and at least two or more of the components in the catalyst may be contacted in advance. The bridged metallocene compound (a) (hereinafter also referred to as "component (a)") is usually used in an amount of 10 -9 ~10 -1 moles, preferably 10 -8 ~10 -2 It is used in molar amounts.

[0124] The organometallic compound (b-1) (hereinafter also referred to as "component (b-1)") is used in an amount such that the molar ratio of component (b-1) to the transition metal atom (M) in component (a) [(b-1) / M] is generally 0.01 to 50,000, preferably 0.05 to 10,000.

[0125] The organoaluminum oxy compound (b-2) (hereinafter also referred to as "component (b-2)") is used in an amount such that the molar ratio of aluminum atoms in component (b-2) to transition metal atoms (M) in component (a) [(b-2) / M] is generally 10 to 5,000, preferably 20 to 2,000.

[0126] The ionic compound (b-3) (hereinafter also referred to as "component (b-3)") is used in an amount such that the molar ratio of component (b-3) to the transition metal atom (M) in component (a) [(b-3) / M] is generally 1 to 10,000, preferably 1 to 5,000.

[0127] The polymerization temperature is usually -50°C to 300°C, preferably 30 to 250°C, more preferably 100°C to 250°C, and even more preferably 130°C to 200°C. Within this polymerization temperature range, as the temperature increases, the solution viscosity during polymerization decreases and the heat of polymerization is easily removed. The polymerization pressure is usually atmospheric pressure to 10 MPa gauge pressure (MPa-G), and preferably atmospheric pressure to 8 MPa-G.

[0128] The polymerization reaction can be carried out in any of batch, semi-continuous, and continuous modes. Furthermore, the polymerization can be carried out continuously in two or more polymerization vessels with different reaction conditions. The molecular weight of the resulting copolymer can be adjusted by changing the hydrogen concentration in the polymerization system or the polymerization temperature. Furthermore, it can also be adjusted by the amount of component (b) used. When hydrogen is added, the amount is preferably about 0.001 to 5,000 nL per kg of the copolymer produced.

[0129] The polymerization solvent used in liquid-phase polymerization is usually an inert hydrocarbon solvent, preferably a saturated hydrocarbon having a boiling point of 50°C to 200°C under normal pressure. Specific examples of polymerization solvents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene, and alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane. Hexane, heptane, octane, decane, and cyclohexane are particularly preferred. The α-olefin itself to be polymerized can also be used as the polymerization solvent. Aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated hydrocarbons such as ethylene chloride, chlorobenzene, and dichloromethane can also be used as polymerization solvents, but their use is undesirable from the standpoint of reducing the burden on the environment and minimizing the impact on human health.

[0130] The kinematic viscosity at 100°C of an olefin polymer depends on the molecular weight of the polymer. That is, a high molecular weight results in a high viscosity, and a low molecular weight results in a low viscosity. Therefore, the kinematic viscosity at 100°C is adjusted by adjusting the molecular weight as described above. In addition, the molecular weight distribution (Mw / Mn) of the obtained polymer can be adjusted by removing low molecular weight components from the obtained polymer using a conventionally known method such as vacuum distillation. Furthermore, the obtained polymer may be subjected to hydrogenation (hereinafter also referred to as hydrogenation) using a conventionally known method. If the double bonds of the obtained polymer are reduced by hydrogenation, the oxidation stability and heat resistance are improved.

[0131] The resulting ethylene-α-olefin copolymer (C) may be used alone, or two or more types having different molecular weights or different monomer compositions may be used in combination. The ethylene-α-olefin copolymer (C) may be graft-modified with a functional group, or may be further secondarily modified by methods such as those described in JP-A-61-126120 and Japanese Patent No. 2593264, and examples of secondary modification include the method described in JP-A-2008-508402.

[0132] <(A) Mineral oil> (A) Mineral oil has the following characteristics (A1) to (A3). (A1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s This value of kinematic viscosity at 100°C is measured according to the method described in JIS K2283. (A) The kinematic viscosity of mineral oil at 100°C is 2 to 8 mm 2 / s, preferably 2 to 6 mm 2 / s, preferably 3 to 5 mm 2 When the kinematic viscosity at 100°C is within this range, the lubricating oil composition of the present invention is excellent in terms of the balance of volatility and temperature-viscosity characteristics.

[0133] (A2) Viscosity index is 90 or more This viscosity index value is measured according to the method described in JIS K 2283. The viscosity index of (A) mineral oil is 90 or higher, preferably 100 or higher, and more preferably 105 or higher. When the viscosity index is within this range, the lubricating oil composition of the present invention has excellent temperature-viscosity characteristics.

[0134] (A3) The pour point is 0°C or less This pour point value is measured according to the method described in ASTM D97. The pour point of (A) mineral oil is 0° C. or lower, preferably −5° C. or lower, more preferably −10° C. or lower, and even more preferably −12° C. or lower. When the pour point is within this range, the lubricating oil composition of the present invention has excellent low-temperature viscosity characteristics.

[0135] <(B) Synthetic oil> (B) Synthetic oil has the following characteristics (B1) to (B3). (B1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s This value of kinematic viscosity at 100°C is measured according to the method described in JIS K2283. (B) The kinematic viscosity of synthetic oil at 100°C is 2 to 8 mmH 2 / s, preferably 2 to 6 mm 2 / s, preferably 3 to 5 mm 2 When the kinematic viscosity at 100°C is within this range, the lubricating oil composition of the present invention is excellent in terms of the balance of volatility and temperature-viscosity characteristics.

[0136] (B2) Viscosity index is 110 or more This viscosity index value is measured according to the method described in JIS K 2283. The viscosity index of (B) synthetic oil is 110 or higher, preferably 115 or higher, and more preferably 120 or higher. When the viscosity index is within this range, the lubricating oil composition of the present invention has excellent temperature-viscosity characteristics.

[0137] (B3) The pour point is -30°C or less This pour point value is measured according to the method described in ASTM D97. The pour point of (B) synthetic oil is −30° C. or lower, preferably −40° C. or lower, more preferably −50° C. or lower, and even more preferably −60° C. or lower. When the pour point is within this range, the lubricating oil composition of the present invention has excellent low-temperature viscosity characteristics.

[0138] The lubricating base oils used in the present invention vary in performance and quality, such as viscosity characteristics, heat resistance, and oxidation stability, depending on their production method and refining method, but are generally broadly classified as mineral oils and synthetic oils. The American Petroleum Institute (API) classifies lubricating base oils into five categories: Groups I, II, III, IV, and V. These API categories are defined in API Publication 1509, 15th Edition, Appendix E, April 2002, and are shown in Table 1. (A) Mineral oils may be any of API categories I to III, and (B) synthetic oils may be any of API categories IV and V. Details are provided below.

[0139] [Table 1]

[0140] *1:Measured according to ASTM D445 (JIS K2283) *2:Measured according to ASTM D3338 *3:Measured according to ASTM D4294 (JIS K2541) *2: Mineral oils with saturated hydrocarbons less than 90% by volume and sulfur content exceeding 0.03% by weight are also included in Group I.

[0141] <(A) Mineral oil> (A) Mineral oils are classified into Groups I to III in the above API categories. (A) The quality of mineral oil is as described above, and mineral oils of the respective qualities described above can be obtained by the refining method. Specific examples of mineral oils include those obtained by subjecting lubricating oil fractions obtained by vacuum distillation of atmospheric residue obtained by atmospheric distillation of crude oil to one or more treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, and hydrorefining, and by refining these fractions, as well as lubricating oil base oils such as wax isomerized mineral oil.

[0142] Gas-to-liquid (GTL) base oils obtained by the Fischer-Tropsch process are also suitable as Group III mineral oils. Such GTL base oils, sometimes referred to as Group III+ lubricant base oils, are described, for example, in patent documents EP 0776959, EP 0668342, WO 97 / 21788, WO 00 / 15736, WO 00 / 14188, WO 00 / 14187, WO 00 / 14183, WO 00 / 14179, WO 00 / 08115, WO 99 / 41332, EP 1029029, WO 01 / 18156, and WO 01 / 57166.

[0143] <(B) Synthetic oil> (B) Synthetic oils are classified in Group IV or Group V of the above API categories.

[0144] Poly-α-olefins belonging to Group IV can be obtained by oligomerization using an acid catalyst such as boron trifluoride or a chromic acid catalyst, as described in U.S. Pat. Nos. 3,382,291, 3,763,244, 5,171,908, 3,780,128, 4,032,591, JP-A-1-163136, 4,967,032, and 4,926,004. It can also be obtained by a method using a catalyst system that uses a transition metal complex of zirconium, titanium, hafnium, or the like containing a metallocene compound, as described in JP-A Nos. 63-037102, 2005-200447, 2005-200448, JP-A Nos. 2009-503147, and 2009-501836. When a poly-α-olefin is used as the lubricating oil base oil, a lubricating oil composition that is extremely excellent in temperature viscosity characteristics, low-temperature viscosity characteristics, and heat resistance can be obtained.

[0145] Poly-α-olefins are commercially available and have a kinematic viscosity of 5mm at 40°C. 2 / s~4,000mm 2 / s are commercially available. 2 The use of poly-α-olefins with a viscosity of 1 / s is preferred because it provides lubricating oil compositions with excellent temperature-viscosity characteristics. Examples include the NEXBASE2000 series manufactured by NESTE, Spectrasyn manufactured by ExxonMobil Chemical, Durasyn manufactured by Ineos Oligmers, and Synfluid manufactured by Chevron Phillips Chemical.

[0146] Examples of synthetic oils belonging to Group V include alkylbenzenes, alkylnaphthalenes, isobutene oligomers or hydrogenated products thereof, paraffins, polyoxyalkylene glycols, dialkyldiphenyl ethers, polyphenyl ethers, and esters.

[0147] The majority of alkylbenzenes and alkylnaphthalenes are dialkylbenzenes or dialkylnaphthalenes, typically having alkyl chain lengths of 6 to 14 carbon atoms. These alkylbenzenes or alkylnaphthalenes are produced by the Friedel-Crafts alkylation reaction of benzene or naphthalene with an olefin. The alkylated olefin used in the production of alkylbenzenes or alkylnaphthalenes may be a linear or branched olefin or a combination thereof. The production methods are described, for example, in U.S. Pat. No. 3,909,432.

[0148] Furthermore, the ester is preferably a fatty acid ester from the viewpoint of compatibility with the (C) ethylene-α-olefin copolymer. The fatty acid ester is not particularly limited, but examples thereof include fatty acid esters consisting only of carbon, oxygen, and hydrogen, such as monoesters produced from monobasic acids and alcohols; diesters produced from dibasic acids and alcohols, or from diols and monobasic acids or acid mixtures; and polyol esters produced by reacting diols, triols (e.g., trimethylolpropane), tetraols (e.g., pentaerythritol), hexaols (e.g., dipentaerythritol), or the like with monobasic acids or acid mixtures. Examples of these esters include ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, tridecyl pelargonate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, trimethylolpropane caprylate, trimethylolpropane pelargonate, trimethylolpropane triheptanoate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, pentaerythritol tetraheptanoate, and the like.

[0149] From the viewpoint of compatibility with (C) ethylene-α-olefin copolymer, the alcohol moiety constituting the ester is preferably an alcohol having a hydroxyl group with two or more functional groups, and the fatty acid moiety is preferably a fatty acid having eight or more carbon atoms. However, in terms of production costs, fatty acids having 20 or fewer carbon atoms, which are easily available industrially, are advantageous. The ester may be composed of a single fatty acid, or the effects of the present invention can be fully achieved even when a fatty acid ester produced using a mixture of two or more acids is used. More specific examples of fatty acid esters include trimethylolpropane lauric acid stearic acid mixed triester and diisodecyl adipate, which are preferred from the viewpoint of compatibility with saturated hydrocarbon components such as (C) ethylene-α-olefin copolymer and stabilizers having polar groups, such as antioxidants, corrosion inhibitors, antiwear agents, friction modifiers, pour point depressants, rust inhibitors, and antifoaming agents, which will be described later.

[0150] When the lubricating oil composition of the present invention uses (B) a synthetic oil, particularly a poly-α-olefin, as the lubricating oil base oil, it preferably contains 1 to 20 mass% of fatty acid ester, based on 100 mass% of the total lubricating oil composition. By containing 1 mass% or more of fatty acid ester, good compatibility with lubricating oil sealants such as resins and elastomers used in various internal combustion engines and industrial machinery can be achieved. Specifically, swelling of the lubricating oil sealant can be suppressed. From the viewpoint of oxidation stability or heat resistance, the amount of ester is preferably 20 mass% or less. When a mineral oil is contained in the lubricating oil composition, fatty acid ester is not necessarily required, since the mineral oil itself has the effect of suppressing swelling of the lubricating oil sealant.

[0151] (B) Synthetic oil is preferred because it has superior heat resistance and temperature-viscosity characteristics compared to (A) mineral oil. In the lubricating oil composition of the present invention, either (A) mineral oil or (B) synthetic oil may be used alone as the lubricating base oil, or an arbitrary mixture of two or more lubricating oils selected from (A) mineral oil and (B) synthetic oil may be used.

[0152] The lubricating oil composition for automobile transmissions according to the present invention contains the (A) mineral oil and / or (B) synthetic oil and the (C) ethylene-α-olefin copolymer, and has the following characteristic (D1):

[0153] (D1) Kinematic viscosity at 100 ° C is 4 to 10 mm 2 / s The kinematic viscosity at 100°C (measured in accordance with the method described in JIS K2283) is 4 to 10 mm 2 / s, preferably 4 to 7.5 mm 2 / s, more preferably 4 to 6.5 mm 2 / s, more preferably 4.2 to 6 mm 2 The kinematic viscosity of the lubricating oil composition for automobile transmissions at 100°C is 10mm / s. 2 If the lubricant is excessively exceeded, the agitation resistance of the lubricant to the gears or metal chains will increase, resulting in poor fuel efficiency. 2 If / s is too small, metal contact between gears or metal chains may occur.

[0154] The lubricating oil composition for automobile transmissions according to the present invention preferably further has the characteristics (D2) and (D3). (D2) Viscosity index is 120 or more This viscosity index (measured according to the method described in JIS K2283) is preferably at least 120, more preferably at least 130, even more preferably at least 140, and particularly preferably at least 150. When the viscosity index is within this range, the lubricating oil composition has excellent temperature viscosity characteristics, making it possible to achieve both energy saving and lubricity over a wide temperature range.

[0155] (D3) The pour point is -20°C or less The pour point of the lubricating oil composition for automobile transmissions according to the present invention (pour point measured according to the method described in ASTM D97) is preferably −20° C. or lower, more preferably −30° C. or lower, and even more preferably −40° C. or lower. A low pour point indicates that the lubricating oil composition has excellent low-temperature properties.

[0156] The lubricating oil composition for automobile transmissions of the present invention preferably contains 90 to 99 mass% of the lubricating base oil consisting of the (A) mineral oil and / or (B) synthetic oil, and 10 to 1 mass% of the (C) ethylene-α-olefin copolymer, where the total of the lubricating base oil and the (C) ethylene-α-olefin copolymer is taken as 100 mass%. The lubricating oil composition for automobile transmissions of the present invention preferably contains 92 to 99 mass% of the lubricating base oil and 8 to 1 mass% of the (C) ethylene-α-olefin copolymer, more preferably 95 to 99 mass% of the lubricating base oil and 5 to 1 mass% of the (C) ethylene-α-olefin copolymer, and even more preferably 96 to 99 mass% of the lubricating base oil and 4 to 1 mass% of the (C) ethylene-α-olefin copolymer.

[0157] In one preferred embodiment, 30 to 100 mass% of the lubricating base oil is (A) mineral oil. When the proportion of (A) mineral oil in the lubricating base oil is high, the solubility of the additives described below is excellent, and it is easy to obtain and economical. It is more preferable that the proportion is 50 to 100 mass%, and even more preferable that the proportion is 80 to 100 mass%. Among mineral oils, Group III in the API category is preferred because it has excellent temperature viscosity characteristics and can achieve both oil film retention at high temperatures and low torque at low temperatures.

[0158] Another preferred embodiment is one in which 30 to 100 mass% of the lubricating base oil is (B) synthetic oil, and the (B) synthetic oil is poly-α-olefin and / or ester oil. It is more preferable that the (B) synthetic oil accounts for 50 to 100 mass%, and even more preferable that the (B) synthetic oil accounts for 80 to 100 mass%. A high proportion of (B) synthetic oil in the lubricating base oil is preferred because it provides excellent heat resistance, temperature-viscosity characteristics, and low-temperature characteristics.

[0159] The lubricating oil composition for automobile transmissions of the present invention may also contain additives such as extreme pressure agents, detergents and dispersants, viscosity index improvers, antioxidants, corrosion inhibitors, anti-wear agents, friction modifiers, pour point depressants, rust inhibitors and anti-foaming agents.

[0160] Examples of additives that can be used in the lubricating oil composition of the present invention include the following, which can be used alone or in combination of two or more. Extreme pressure agents are a general term for substances that have the effect of preventing seizure when metals are exposed to high load conditions, and include, but are not limited to, sulfur-based extreme pressure agents such as sulfides, sulfoxides, sulfones, thiophosphinates, thiocarbonates, sulfurized oils and fats, and sulfurized olefins; phosphoric acids such as phosphate esters, phosphites, phosphate ester amine salts, and phosphites ester amines; and halogen-based compounds such as chlorinated hydrocarbons. Two or more of these compounds may also be used in combination.

[0161] Furthermore, before extreme-pressure lubrication conditions are reached, hydrocarbons or other organic components constituting the lubricating oil composition may carbonize due to heating and shearing, forming a carbide film on the metal surface. Therefore, when an extreme-pressure agent is used alone, the carbide film may inhibit contact between the extreme-pressure agent and the metal surface, and the full effect of the extreme-pressure agent may not be expected.

[0162] Although the extreme pressure agent may be added alone, since the lubricating oil composition for automobile transmissions in the present invention is mainly composed of saturated hydrocarbons such as copolymers, it is preferable from the viewpoint of dispersibility to add it in a state where it is dissolved in a lubricating base oil such as a mineral oil or a synthetic hydrocarbon oil together with other additives to be used in advance. Specifically, it is more preferable to select a so-called additive package in which various components such as the extreme pressure agent component are blended in advance and further dissolved in a lubricating base oil such as a mineral oil or a synthetic hydrocarbon oil, and then add it to the lubricating oil composition.

[0163] For automatic transmission fluids and continuously variable transmission fluids, so-called DI packages are supplied industrially in which various necessary additives are blended for this purpose and concentrated and dissolved in lubricating oils such as mineral oils or synthetic hydrocarbon oils. For example, DI packages for automatic transmission fluids include HITEC 3419D and HITEC 2426 manufactured by Afton Chemical Corporation, and DI packages for continuously variable transmission fluids include Lubrizol 6373 manufactured by Lubrizol Corporation. These DI packages can also be used in the lubricating oil composition of the present invention.

[0164] The extreme pressure agent is used in an amount of 0 to 10% by mass based on 100% by mass of the lubricating oil composition, as needed. Examples of anti-wear agents include inorganic or organic molybdenum compounds such as molybdenum disulfide, graphite, antimony sulfide, and polytetrafluoroethylene. The anti-wear agent is used in an amount of 0 to 3% by mass based on 100% by mass of the lubricating oil composition, as needed.

[0165] Examples of friction modifiers include amine compounds, imide compounds, fatty acid esters, fatty acid amides, and fatty acid metal salts, each of which has at least one alkyl or alkenyl group having 6 to 30 carbon atoms, particularly at least one linear alkyl or alkenyl group having 6 to 30 carbon atoms, in the molecule.

[0166] Examples of amine compounds include linear or branched, preferably linear, aliphatic monoamines having 6 to 30 carbon atoms, linear or branched, preferably linear aliphatic polyamines, and alkylene oxide adducts of these aliphatic amines. Examples of imide compounds include succinimides having linear or branched alkyl or alkenyl groups having 6 to 30 carbon atoms and / or compounds thereof modified with carboxylic acid, boric acid, phosphoric acid, sulfuric acid, etc. Examples of fatty acid esters include esters of linear or branched, preferably linear, fatty acids having 7 to 31 carbon atoms and aliphatic monohydric alcohols or aliphatic polyhydric alcohols. Examples of fatty acid amides include amides of linear or branched, preferably linear, fatty acids having 7 to 31 carbon atoms and aliphatic monoamines or aliphatic polyamines. Examples of fatty acid metal salts include alkaline earth metal salts (magnesium salts, calcium salts, etc.) and zinc salts of straight-chain or branched, preferably straight-chain, fatty acids having 7 to 31 carbon atoms.

[0167] Friction modifiers are used as needed in a range of 0.01 to 5.0 mass% relative to 100 mass% of the lubricating oil composition. Examples of detergent-dispersants include metal sulfonates, metal phenates, metal phosphanates, and succinimides. Detergent-dispersants are used as needed in a range of 0 to 15 mass% relative to 100 mass% of the lubricating oil composition.

[0168] Viscosity index improvers include ethylene-α-olefin copolymers (excluding (C) ethylene-α-olefin copolymers), as well as olefin copolymers with a molecular weight exceeding 50,000, methacrylate copolymers, liquid polybutene, and viscosity improvers with a kinematic viscosity of 15 mm at 100°C. 2 A known viscosity index improver such as a poly-α-olefin having a viscosity index of 1 / s or more can be used in combination. The viscosity index improver is used in an amount of 0 to 50% by mass relative to 100% by mass of the lubricating oil composition, as needed.

[0169] Examples of antioxidants include phenolic and amine compounds such as 2,6-di-t-butyl-4-methylphenol, and the antioxidant is used in an amount of 0 to 3 mass % relative to 100 mass % of the lubricating oil composition, as needed.

[0170] Examples of corrosion inhibitors include compounds such as benzotriazole, benzimidazole, thiadiazole, etc. The corrosion inhibitor is used in an amount of 0 to 3% by mass relative to 100% by mass of the lubricating oil composition, as required.

[0171] Examples of the rust inhibitor include various amine compounds, metal carboxylates, polyhydric alcohol esters, phosphorus compounds, sulfonates, etc. The rust inhibitor is used in an amount of 0 to 3 mass % relative to 100 mass % of the lubricating oil composition, as needed.

[0172] Examples of antifoaming agents include silicone compounds such as dimethylsiloxane and silica gel dispersions, alcohol-based or ester-based compounds, etc. Antifoaming agents are used in an amount of 0 to 0.2% by mass relative to 100% by mass of the lubricating oil composition, as needed.

[0173] As the pour point depressant, various known pour point depressants can be used. Specifically, a polymer compound containing an organic acid ester group is used, and a vinyl polymer containing an organic acid ester group is particularly preferably used. Examples of the vinyl polymer containing an organic acid ester group include alkyl methacrylate (co)polymers, alkyl acrylate (co)polymers, alkyl fumarate (co)polymers, alkyl maleate (co)polymers, and alkylated naphthalene.

[0174] Such pour point depressants have a melting point of -13°C or lower, preferably -15°C or lower, and more preferably -17°C or lower. The melting point of the pour point depressant is measured using a differential scanning calorimeter (DSC). Specifically, about 5 mg of a sample is placed in an aluminum pan, heated to 200°C, held at 200°C for 5 minutes, cooled to -40°C at 10°C / min, held at -40°C for 5 minutes, and then heated at 10°C / min. The melting point is determined from the endothermic curve.

[0175] The pour point depressant further has a weight average molecular weight, as determined by gel permeation chromatography in the range of 20,000 to 400,000, preferably 30,000 to 300,000, and more preferably 40,000 to 200,000, as calculated in terms of polystyrene.

[0176] The pour point depressant is used as needed in an amount of 0 to 2 mass % relative to 100 mass % of the lubricating oil composition. In addition to the above additives, demulsifiers, colorants, oiliness agents (oiliness improvers), etc. may be used as needed.

[0177] <Application> The lubricating oil composition of the present invention can be suitably used in automotive transmission oils such as manual transmission oils, automatic transmission oils, continuously variable transmission oils, and dual clutch transmission oils, and has extremely excellent temperature viscosity characteristics, i.e., oil film retention at high temperatures and low temperature viscosity characteristics, compared to conventional lubricating oils containing the same lubricating base oil, and greatly contributes to improving the fuel economy of transmissions.In addition, because of its excellent shear stability, it is possible to reduce the viscosity of automatic transmission oils, which can contribute to further improving fuel economy.The lubricating oil composition of the present invention is particularly useful as a dual clutch transmission oil, where high shear stress is applied to the transmission oil and the stirring resistance of the transmission oil is greatly affected. [Example]

[0178] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.

[0179] [Evaluation method] In the following examples and comparative examples, the physical properties of the ethylene-α-olefin copolymers and lubricating oils for automobile transmissions were measured by the following methods.

[0180] <Ethylene content (mol%)> Using a Fourier transform infrared spectrophotometer FT / IR-610 or FT / IR-6100 manufactured by JASCO Corporation, the absorbance ratio (D1155 cm -1 near 1155 cm -1 / D721 cm -1 near 721 cm -1 ) based on the absorption near 721 cm due to the wagging vibration of the long-chain methylene group and the absorption near 1155 cm due to the skeletal vibration of propylene was calculated, and the ethylene content (wt%) was determined from a calibration curve prepared in advance (prepared using a standard sample in ASTM D3900). Next, using the obtained ethylene content (wt%), the ethylene content (mol%) was determined according to the following formula. <000092​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ In formula [1], P E indicates the mole fraction of ethylene component, and P O indicates the mole fraction of α-olefin components, and P OE indicates the mole fraction of ethylene-α-olefin chains in all dyad chains.

[0186] <Molecular weight distribution> The molecular weight distribution was measured using a Tosoh Corporation HLC-8320GPC as follows. Four TSKgel SuperMultiporeHZ-M columns were used as separation columns. The column temperature was 40°C, the mobile phase was tetrahydrofuran (Wako Pure Chemical Industries, Ltd.), the development rate was 0.35 ml / min, the sample concentration was 5.5 g / L, the sample injection volume was 20 microliters, and a differential refractometer was used as the detector. Tosoh Corporation PStQuick MP-M polystyrene standards were used. According to the general-purpose calibration procedure, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were calculated in terms of polystyrene molecular weight, and the molecular weight distribution (Mw / Mn) was calculated from these values.

[0187] <Melting point> Using a Seiko Instruments X-DSC-7000, approximately 8 mg of ethylene-α-olefin copolymer was placed in a sealable aluminum sample pan and placed in a DSC cell. The DSC cell was heated from room temperature to 150°C at 10°C / min under a nitrogen atmosphere, then held at 150°C for 5 minutes and cooled at 10°C / min to -100°C (cooling down process). The sample was then held at 100°C for 5 minutes and then heated at 10°C / min. The temperature at which the enthalpy curve obtained during the heating process reached its maximum was defined as the melting point (Tm), and the sum of the endotherms associated with melting was defined as the heat of fusion (ΔH). If no peak was observed or the heat of fusion (ΔH) was less than 1 J / g, the melting point (Tm) was considered absent. The melting point (Tm) and heat of fusion (ΔH) were determined according to JIS K7121.

[0188] <Chlorine content> Using a Thermo Fisher Scientific ICS-1600, an ethylene-α-olefin copolymer was placed in a sample boat and subjected to combustion decomposition in an Ar / O gas flow at a furnace set temperature of 900°C. The generated gas was absorbed in an absorption liquid and quantified by ion chromatography.

[0189] <Weighing accuracy> 100 g of polymer heated to 80°C was added using a gear pump to a 2 L separable flask placed on an electronic balance. After stopping the pump, dripping from the discharge port was confirmed, and if there was a difference of 5% or more from the specified weight, it was considered that there was dripping during measurement.

[0190] <Solubility> 100 g of polymer was weighed into a 2 L separable flask, and 900 g of mineral oil (described later) was added. After heating to 80°C, the mixture was stirred at 100 rpm with a stirring rod, and the time required for complete homogeneous dissolution was measured visually every 30 minutes. If undissolved material was still observed after 3 hours of stirring, the result was recorded as "not dissolved."

[0191] <Kinematic viscosity> The kinematic viscosity at 100°C and the kinematic viscosity at 40°C were measured according to the method described in JIS K2283.

[0192] <Low temperature viscosity> The low-temperature viscosity was measured at -40°C according to the method described in ASTM D6821. Viscosity exceeding 20,000 mPa·s was deemed unmeasurable.

[0193] <Shear stability> With regard to the shear stability of the lubricating oil compositions, a shear test was carried out on the lubricating oil compositions using a KRL shear tester in accordance with the method described in CRC L-45-T-93 under shear conditions of a test time of 20 hours, a test temperature of 60°C, and a bearing rotation speed of 1450 rpm, and the kinematic viscosity at 100°C after the test was measured.

[0194] [Production of ethylene-α-olefin copolymer (B)] The ethylene-α-olefin copolymer (B) was produced according to the following polymerization example: The resulting ethylene-α-olefin copolymer (B) was hydrogenated as required by the following method.

[0195] <Hydrogenation operation> A 1 L stainless steel autoclave was charged with 100 mL of a hexane solution of 0.5 mass % Pd / alumina catalyst and 500 mL of a 30 mass % hexane solution of ethylene-α-olefin copolymer, and the autoclave was sealed and then purged with nitrogen. The temperature was then raised to 140°C with stirring, and the system was purged with hydrogen. The pressure was then raised to 1.5 MPa with hydrogen, and the hydrogenation reaction was carried out for 15 minutes.

[0196] <Synthesis of metallocene compounds> [Synthesis Example 1] [Methylphenylmethylene (η 5 -cyclopentadienyl)(η 5 Synthesis of [(2,7-di-t-butylfluorenyl)]zirconium dichloride (i) Synthesis of 6-methyl-6-phenylfulvene Under a nitrogen atmosphere, 7.3 g (101.6 mmol) of lithium cyclopentadiene and 100 mL of dehydrated tetrahydrofuran were added to a 200 mL three-neck flask and stirred. The solution was cooled in an ice bath, and 15.0 g (111.8 mmol) of acetophenone was added dropwise. The mixture was then stirred at room temperature for 20 hours, and the resulting solution was quenched with dilute aqueous hydrochloric acid. 100 mL of hexane was added to extract the soluble matter. This organic layer was washed with water and saturated brine and then dried over anhydrous magnesium sulfate. The solvent was then distilled off, and the resulting viscous liquid was separated by column chromatography (hexane) to obtain the target product (red viscous liquid).

[0197] (ii) Synthesis of methyl(cyclopentadienyl)(2,7-di-t-butylfluorenyl)(phenyl)methane Under a nitrogen atmosphere, 2.01 g (7.20 mmol) of 2,7-di-t-butylfluorene and 50 mL of dehydrated t-butyl methyl ether were added to a 100 mL three-neck flask. While cooling in an ice bath, 4.60 mL (7.59 mmol) of a 1.65 M n-butyllithium / hexane solution was gradually added, and the mixture was stirred at room temperature for 16 hours. 1.66 g (9.85 mmol) of 6-methyl-6-phenylfulvene was then added, and the mixture was heated to reflux and stirred for 1 hour. While cooling in an ice bath, 50 mL of water was gradually added, and the resulting bilayer solution was transferred to a 200 mL separatory funnel. 50 mL of diethyl ether was added, and the mixture was shaken several times. The aqueous layer was removed, and the organic layer was washed three times with 50 mL of water and once with 50 mL of saturated brine. The mixture was dried over anhydrous magnesium sulfate for 30 minutes, and the solvent was evaporated under reduced pressure. A small amount of hexane was added to the resulting solution, and the resulting solution was sonicated, resulting in the precipitation of a solid. This solid was collected and washed with a small amount of hexane. After drying under reduced pressure, 2.83 g of methyl(cyclopentadienyl)(2,7-di-t-butylfluorenyl)(phenyl)methane was obtained as a white solid.

[0198] (iii) [methylphenylmethylene (η 5 -cyclopentadienyl)(η 5 Synthesis of [(2,7-di-t-butylfluorenyl)]zirconium dichloride Under a nitrogen atmosphere, 1.50 g (3.36 mmol) of methyl(cyclopentadienyl)(2,7-di-t-butylfluorenyl)(phenyl)methane, 50 mL of anhydrous toluene, and 570 μL (7.03 mmol) of THF were sequentially added to a 100 mL Schlenk tube. While cooling in an ice bath, 4.20 mL (6.93 mmol) of a 1.65 M n-butyllithium / hexane solution was slowly added, and the mixture was stirred at 45 °C for 5 hours. The solvent was evaporated under reduced pressure, and 40 mL of anhydrous diethyl ether was added to obtain a red solution. While cooling in a methanol / dry ice bath, 728 mg (3.12 mmol) of zirconium tetrachloride was added, and the mixture was stirred for 16 hours while gradually warming to room temperature, resulting in a red-orange slurry. The solvent was evaporated under reduced pressure, and the resulting solid was brought into a glove box, washed with hexane, and then extracted with dichloromethane. After concentrating the mixture by distilling off the solvent under reduced pressure, a small amount of hexane was added and the mixture was left at -20°C, whereupon a reddish-orange solid precipitated. This solid was washed with a small amount of hexane and then dried under reduced pressure to obtain [methylphenylmethylene(η)] as a reddish-orange solid. 5 -cyclopentadienyl)(η 5 1.20 g of 2,7-di-t-butylfluorenyl)]zirconium dichloride was obtained.

[0199] [Synthesis Example 2] [Ethylene (η 5 -cyclopentadienyl)(η 5 Synthesis of [(2,7-di-t-butylfluorenyl)]zirconium dichloride [Ethylene (η 5 -cyclopentadienyl)(η 5 [-2,7-di-t-butylfluorenyl)]zirconium dichloride was synthesized by the method described in Japanese Patent No. 4367687.

[0200] <Polymerization Example 1> A 2 L stainless steel autoclave was charged with 910 mL of heptane and 50 g of propylene, and the temperature inside the system was raised to 130°C. After that, 0.082 MPa of hydrogen and 0.082 MPa of ethylene were added to the system to adjust the total pressure to 1 MPaG. Next, 0.4 mmol of triisobutylaluminum and [methylphenylmethylene (η 5 -cyclopentadienyl)(η 5 0.0006 mmol of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (2,7-di-t-butylfluorenyl)zirconium dichloride and 0.006 mmol of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were introduced under nitrogen pressure, and the agitation speed was increased to 400 rpm to initiate polymerization. Subsequently, the total pressure was maintained at 1 MPaG by continuously supplying only ethylene, and polymerization was carried out for 5 minutes at 130 °C. The polymerization was terminated by adding a small amount of ethanol to the system, after which unreacted ethylene, propylene, and hydrogen were purged. The resulting polymer solution was washed three times with 1000 mL of 0.2 mol / L hydrochloric acid and then three times with 1000 mL of distilled water. After drying over magnesium sulfate, the solvent was removed by distillation under reduced pressure. The obtained polymer was dried overnight under reduced pressure at 80°C, and then further subjected to thin-film distillation using a Kobe Steel Pantec 2-03 thin-film distillation apparatus, maintaining the reduced pressure at 400 Pa, setting the temperature at 180°C, and flow rate at 3.1 ml / min, to obtain 26 g of ethylene-propylene copolymer.

[0201] <Polymerization Example 2> A 2 L stainless steel autoclave was charged with 910 mL of heptane and 50 g of propylene, and the temperature inside the system was raised to 130°C. After that, hydrogen (0.047 MPa) and ethylene (0.085 MPa) were added to the system to adjust the total pressure to 1 MPaG. Next, 0.4 mmol of triisobutylaluminum and [methylphenylmethylene (η 5 -cyclopentadienyl)(η 50.0006 mmol of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (2,7-di-t-butylfluorenyl)zirconium dichloride and 0.006 mmol of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were introduced under nitrogen pressure, and the agitation speed was increased to 400 rpm to initiate polymerization. Subsequently, the total pressure was maintained at 1 MPaG by continuously supplying only ethylene, and polymerization was carried out for 5 minutes at 130 °C. The polymerization was terminated by adding a small amount of ethanol to the system, after which unreacted ethylene, propylene, and hydrogen were purged. The resulting polymer solution was washed three times with 1000 mL of 0.2 mol / L hydrochloric acid and then three times with 1000 mL of distilled water. After drying over magnesium sulfate, the solvent was removed by distillation under reduced pressure. The obtained polymer was dried overnight under reduced pressure at 80°C, and then further subjected to thin-film distillation using a Kobe Steel Pantec 2-03 thin-film distillation apparatus, maintaining the reduced pressure at 400 Pa, setting the temperature at 180°C, and flow rate at 3.1 ml / min, to obtain 26 g of ethylene-propylene copolymer.

[0202] <Polymerization Example 3> A 1 L glass polymerization vessel was charged with 250 mL of heptane and thoroughly purged with nitrogen. The temperature inside the system was raised to 50°C, and then ethylene was continuously fed into the vessel at a flow rate of 25 L / hr, propylene at 75 L / hr, and hydrogen at 100 L / hr. The vessel was stirred at 600 rpm. Next, 0.2 mmol of triisobutylaluminum was charged into the vessel, followed by 0.688 mmol of MMAO and [ethylene (η 5 -cyclopentadienyl)(η 5Polymerization was initiated by charging 0.00230 mmol of (2,7-di-t-butylfluorenyl)zirconium dichloride, which had been premixed in toluene for over 15 minutes, into the polymerization vessel. Ethylene, propylene, and hydrogen were then continuously supplied, and polymerization was carried out for 15 minutes at 50°C. The polymerization was terminated by adding a small amount of isobutyl alcohol to the system, after which unreacted monomer was purged. The resulting polymer solution was washed three times with 100 mL of 0.2 mol / L hydrochloric acid and then three times with 100 mL of distilled water. After drying over magnesium sulfate, the solvent was removed under reduced pressure. The resulting polymer was dried overnight at 80°C under reduced pressure, yielding 1.43 g of ethylene-propylene copolymer. This ethylene-propylene copolymer was then hydrogenated.

[0203] <Polymerization Example 4> A 1 L glass polymerization vessel was charged with 250 mL of decane and the temperature in the system was raised to 130°C. Ethylene was continuously fed into the vessel at a flow rate of 25 L / hr, propylene at 75 L / hr, and hydrogen at 100 L / hr, and the vessel was stirred at 600 rpm. Next, 0.2 mmol of triisobutylaluminum was charged into the vessel, followed by 1.213 mmol of MMAO and [methylphenylmethylene (η 5 -cyclopentadienyl)(η 5 Polymerization was initiated by charging 0.00402 mmol of (2,7-di-t-butylfluorenyl)zirconium dichloride, which had been premixed in toluene for over 15 minutes, into the polymerization vessel. Ethylene, propylene, and hydrogen were then continuously supplied, and polymerization was carried out at 130°C for 15 minutes. The polymerization was terminated by adding a small amount of isobutyl alcohol to the system, and unreacted monomer was purged. The resulting polymer solution was washed three times with 100 mL of 0.2 mol / L hydrochloric acid and then three times with 100 mL of distilled water. After drying over magnesium sulfate, the solvent was removed under reduced pressure. The resulting polymer was dried overnight at 80°C under reduced pressure, yielding 0.77 g of ethylene-propylene copolymer. This ethylene-propylene copolymer was then hydrogenated.

[0204] The ethylene-propylene copolymers obtained in Polymerization Examples 1 to 4 are designated Polymer 1 to Polymer 4, respectively, and the physical properties of polymethacrylate (PMA), polybutene (PIB), and olefin copolymer (OCP), as well as the evaluation results of their solubility in mineral oil, are shown in Table 2. In addition, the accuracy of weighing for blending was evaluated for liquid polymers excluding OCP, which is solid, and the results are also shown in Table 2. The PMA, PIB, OCP, and mineral oil used are as follows: Polymethacrylate (PMA): Polymethacrylate (Viscoplex 0-220, manufactured by Evonik) with a weight average molecular weight of 41,800 as measured by GPC, similar to that of ethylene-α-olefin copolymer. Polybutene (PIB): A high molecular weight liquid polybutene (Nisseki Polybutene HV-1900 manufactured by ENEOS Corporation) with a weight average molecular weight of 8,400 and a molecular weight distribution of 2.6, as measured by GPC, similar to ethylene-α-olefin copolymer. Olefin copolymer (OCP): a solid olefin copolymer (PARATONE 8900, manufactured by ExxonMobil Chemical Co.) with a weight average molecular weight of 155,000 and a molecular weight distribution of 2.1, as measured by GPC, similar to that of the ethylene-α-olefin copolymer. (A) Mineral oil; Kinematic viscosity at 100℃: 4.3mm 2 / s, viscosity index: 126, pour point: -15°C API (American Petroleum Institute) Group III mineral oil (Yubase-4 manufactured by SK Lubricants) [Table 2]

[0205] [Preparation of Lubricating Oil Composition for Automobile Transmissions] In preparing the lubricating oil composition for automobile transmissions, the following were used in addition to the above-mentioned (C) ethylene-α-olefin copolymer, PMA, PIB, and (A) mineral oil. Pour point depressant: BASF Irgaflow 720P Automotive Transmission Fluid (ATF) Additive Package; Afton Chemical HITEC-3419D

[0206] <Lubricant composition for automobile transmissions> [Example 1] (A) Mineral oil and (C) Polymer 1 are used as an ethylene-α-olefin copolymer, and these, together with an ATF additive package and a pour point depressant, have a kinematic viscosity at 100°C of 6.3 to 6.7 mmHg. 2 Lubricating oil compositions for automobile transmissions were prepared in the blending amounts shown in Table 3 so that the viscosity of the lubricating oil compositions fell within the range of 1 / s. The physical properties of the obtained lubricating oil compositions for automobile transmissions are shown in Table 3.

[0207] [Example 2] A lubricating oil composition for automobile transmissions was formulated and prepared in the same manner as in Example 1, except that Polymer 1 was replaced with Polymer 2 shown in Table 2. The physical properties of the lubricating oil composition for automobile transmissions are shown in Table 3.

[0208] [Example 3] A lubricating oil composition for automobile transmissions was formulated and prepared in the same manner as in Example 1, except that Polymer 1 was replaced with Polymer 3 shown in Table 2. The physical properties of the lubricating oil composition for automobile transmissions are shown in Table 3.

[0209] [Comparative Example 1] Except for replacing Polymer 1 with polymethacrylate (PMA), a lubricating oil composition for automobile transmissions was formulated and prepared in the same manner as in Example 1. The physical properties of the lubricating oil composition for automobile transmissions are shown in Table 3.

[0210] Comparative Example 2 A lubricating oil composition for automobile transmissions was formulated and prepared in the same manner as in Example 1, except that Polymer 1 was replaced with Polymer 4 shown in Table 2. The physical properties of the lubricating oil composition for automobile transmissions are shown in Table 3.

[0211] Comparative Example 3 Except for replacing Polymer 1 with polybutene (PIB), a lubricating oil composition for automobile transmissions was formulated and prepared in the same manner as in Example 1. The physical properties of the lubricating oil composition for automobile transmissions are shown in Table 3. [Table 3]

[0212] The lubricating oil compositions for automobile transmissions of Examples 1 to 3, which contain the ethylene-α-olefin copolymer (C), are different from the lubricating oil composition for automobile transmissions of Comparative Example 1, which contains PMA instead of the ethylene-α-olefin copolymer (C), in that they have a kinematic viscosity at 100°C after a shear test of 6mm. 2 / s or more. That is, the lubricating oil composition for automobile transmissions of the present invention can prevent metal-to-metal contact between gears in automobile transmissions, which have recently been downsized and are increasingly subject to higher loads on gear teeth, thereby providing better gear protection. In addition, lubricating oils for automatic transmissions must be formulated taking into account the viscosity loss due to shear stress during actual use. However, the lubricating oil composition of the present invention exhibits only a small viscosity loss in response to shear stress, making it possible to lower the viscosity during formulation, thereby contributing to the fuel-saving performance of the transmission. Furthermore, the lubricating oil composition for automobile transmissions of Comparative Example 2, which uses Polymer 4, and the lubricating oil composition for automobile transmissions of Comparative Example 3, which contains PIB instead of (C) the ethylene-α-olefin copolymer, have significantly poor low-temperature fluidity and therefore cannot be used in low-temperature environments.

Claims

1. The lubricating oil comprises a lubricating base oil (A) consisting of a mineral oil having the following characteristics (A1) to (A3) and / or a synthetic oil (B) having the following characteristics (B1) to (B3), and an ethylene-α-olefin copolymer (C) having the following characteristics (C1) to (C5), and has a kinematic viscosity at 100°C of 4 to 10 mm 2 A lubricating oil composition for automobile transmissions, comprising: (A1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s (A2) Viscosity index is 90 or more (A3) The pour point is 0°C or less. (B1) Kinematic viscosity at 100 ° C. is 2 to 8 mm 2 / s (B2) The viscosity index is 110 or more. (B3) The pour point is -30°C or less. (C1) The ethylene molar content is in the range of 30 to 70 mol%. (C2) Rotational viscosity at 150°C is 200 to 8,000 mPa·s (C3) Hazen color index is 30 or less (C4) The molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) and calculated as polystyrene is 2.5 or less. (C5) The following formula [1] [Equation 1] (In the formula, P E represents the mole fraction of the ethylene component, and P O represents the molar fraction of the α-olefin component, and P OE indicates the mole fraction of ethylene-α-olefin chains in all dyad chains.) The B value expressed by the formula is 1.1 or more.

2. 2. The lubricating oil composition for automobile transmissions according to claim 1, wherein the ethylene molar content of the ethylene-α-olefin copolymer (C) is in the range of 40 to 60 mol %.

3. 3. A lubricating oil composition for automobile transmissions according to claim 1, wherein the rotational viscosity of the ethylene-α-olefin copolymer (C) at 150° C. is 1,000 to 5,000 mPa·s.

4. 4. The lubricating oil composition for automobile transmissions according to claim 1, wherein the α-olefin in the ethylene-α-olefin copolymer (C) is propylene.

5. 5. The lubricating oil composition for automobile transmissions according to claim 1, wherein the content of the ethylene-α-olefin copolymer (C) is 1 to 10% by mass.

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