US20250171704A1 - Lubricating oil composition - Google Patents

Lubricating oil composition Download PDF

Info

Publication number
US20250171704A1
US20250171704A1 US18/842,784 US202318842784A US2025171704A1 US 20250171704 A1 US20250171704 A1 US 20250171704A1 US 202318842784 A US202318842784 A US 202318842784A US 2025171704 A1 US2025171704 A1 US 2025171704A1
Authority
US
United States
Prior art keywords
group
ethylene
lubricating oil
oil composition
olefin copolymer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
US18/842,784
Other languages
English (en)
Inventor
Hirotaka Kanaya
Shota Abe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsui Chemicals Inc
Original Assignee
Mitsui Chemicals Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsui Chemicals Inc filed Critical Mitsui Chemicals Inc
Assigned to MITSUI CHEMICALS, INC. reassignment MITSUI CHEMICALS, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ABE, SHOTA, KANAYA, Hirotaka
Publication of US20250171704A1 publication Critical patent/US20250171704A1/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M101/00—Lubricating compositions characterised by the base-material being a mineral or fatty oil
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M143/00—Lubricating compositions characterised by the additive being a macromolecular hydrocarbon or such hydrocarbon modified by oxidation
    • C10M143/02—Polyethylene
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M107/00—Lubricating compositions characterised by the base-material being a macromolecular compound
    • C10M107/02—Hydrocarbon polymers; Hydrocarbon polymers modified by oxidation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M111/00—Lubrication compositions characterised by the base-material being a mixture of two or more compounds covered by more than one of the main groups C10M101/00 - C10M109/00, each of these compounds being essential
    • C10M111/02—Lubrication compositions characterised by the base-material being a mixture of two or more compounds covered by more than one of the main groups C10M101/00 - C10M109/00, each of these compounds being essential at least one of them being a non-macromolecular organic compound
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M143/00—Lubricating compositions characterised by the additive being a macromolecular hydrocarbon or such hydrocarbon modified by oxidation
    • C10M143/04—Lubricating compositions characterised by the additive being a macromolecular hydrocarbon or such hydrocarbon modified by oxidation containing propene
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/04—Mixtures of base-materials and additives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
    • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
    • C10M2203/1006—Petroleum or coal fractions, e.g. tars, solvents, bitumen used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/0206—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/022—Ethene
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/026—Butene
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/028—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
    • C10M2209/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C10M2209/08—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type
    • C10M2209/084—Acrylate; Methacrylate
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/011—Cloud point
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/02—Viscosity; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/04—Molecular weight; Molecular weight distribution
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/02—Pour-point; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/08—Resistance to extreme temperature
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/20—Colour, e.g. dyes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/40—Low content or no content compositions
    • C10N2030/41—Chlorine free or low chlorine content compositions
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/68—Shear stability
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/04—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/25—Internal-combustion engines
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2060/00—Chemical after-treatment of the constituents of the lubricating composition
    • C10N2060/02—Reduction, e.g. hydrogenation

Definitions

  • the present invention relates to a lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle.
  • Electric vehicles are one of the mainstream technologies in such fuel saving. Examples thereof include electric automobiles, plug-in hybrid vehicles, hybrid vehicles, and fuel cell vehicles, which are expected to spread rapidly in the future. Electric vehicles are characterized by having electric motors, and run partially or entirely on electric motors.
  • ATF automatic transmission fluid
  • CVTF continuously variable transmission fluid
  • lubricating oil compositions a variety of additives are blended to impart characteristics that control friction in wet clutches and suppress metal-to-metal wear (metal-to-metal wear resistance), and the volume resistivity is about 10 ⁇ 7 ⁇ m. Also, there is a problem of the volume resistivity of these lubricating oil compositions decreasing significantly with the lubricating oil itself deteriorating.
  • lubricating oil compositions used for electric vehicles are required not only to have excellent metal-to-metal wear resistance, but also to have excellent electric insulation in order to maintain reliability over a long period of time in terms of the insulation of electric motors. Furthermore, due to the recent needs for improved fuel saving performance and simplified lubrication systems for transmissions and electric motors, lubricating oil compositions are required to have lower viscosity than that of existing ATF and CVTF, as well as to improve power transmission efficiency and reduce size and weight, resulting in an even higher load being applied to transmissions. Therefore, along with insulation, high wear resistance and durability performance such as shear stability and thermal stability of lubricating oil compositions are also increasingly required.
  • lubricating oil compositions containing specific phosphorous compounds or specific sulfur compounds are proposed in Patent Literatures 1 and 2, and electrical characteristics such as volume resistivity are discussed in addition to lubricating oil performance such as wear resistance and extreme pressure performance of the lubricating oil compositions.
  • In-wheel motors as motors driven inside the wheels of electric vehicles, are increasingly being installed as the power train in electric automobiles and fuel cell vehicles.
  • driving power is transmitted directly to the wheels, thus reducing energy loss due to gears, drive shafts, etc., as in conventional gasoline engine automobiles.
  • In-wheel motors which have low energy loss, require higher heat dissipation since it is difficult for such a mechanism to dissipate heat generated by the transmission and motor.
  • Patent Literature 3 describes that lubricating oils used for in-wheel motors are in a smaller amount compared to ATF and CVTF, and thus their viscosity easily decreases when subjected to severe shear, and lubrication performance tends to be particularly valued.
  • Patent Literature 4 provides an in-wheel motor that can improve fuel saving, as there is a need for lubricating oils used in in-wheel motors to extend the driving distance per battery charging as much as possible, such as for electric wheelchairs.
  • chassis-type systems in which an electric motor and a transmission that transfers power from the electric motor to the drive unit, or a speed reduction mechanism are integrated, and an increasing number of vehicles are employing this type of system. Therefore, in addition to the conventional lubricating function, lubricating oils are now required to have a cooling function to suppress excessive heat generation in the electric motor. For this reason, there has been a demand for improvement in the electric motor cooling performance of lubricating oils.
  • Patent Literatures do not sufficiently discuss the cooling performance for electric motors, such as heat generation and heat dissipation suppression, and there is still room for improvement in the cooling performance of lubricating oil compositions.
  • an object to be solved by the present invention is to provide a lubricating oil composition that is extremely excellent in shear stability and is excellent, with a good balance at a high level, in temperature viscosity characteristics such as oil film retention performance at a high temperature and pourability at a low temperature, compared to conventional lubricating oils containing the same lubricating base oil, the lubricating oil composition also having high heat dissipation performance from the viewpoint of cooling of an electric motor.
  • a lubricating oil composition containing a specific ethylene- ⁇ -olefin (co)polymer with a specific lubricating base oil and satisfying specific conditions can solve the aforementioned problems, and thus have completed the present invention. Specifically, the following aspects are included:
  • a lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle including: a lubricating base oil composed of a (A) mineral oil having the following characteristics (A1) to (A3) and/or a (B) synthetic oil having the following characteristics (B1) to (B3); and an (C) ethylene- ⁇ -olefin copolymer having the following characteristics (C1) to (C5), the composition having a kinematic viscosity at 100° C. of 4 to 10 mm 2 /s:
  • P E represents a molar fraction of ethylene component
  • P O represents a molar fraction of ⁇ -olefin component
  • P OE represents a molar fraction of ethylene- ⁇ -olefin sequence in the total dyad sequence
  • the lubricating oil composition according to any of [1] to [5], wherein the content of the (C) ethylene- ⁇ -olefin copolymer is 1 to 10% by mass based on the total amount of the lubricating base oil and the (C) ethylene- ⁇ -olefin copolymer of 100% by mass.
  • the lubricating oil composition of the present invention is a lubricating oil composition that is, compared to conventional lubricating oils containing the same lubricating base oil, extremely superior in temperature viscosity characteristics, that is, excellent, with a good balance at a high level, in temperature viscosity characteristics such as oil film retention at a high temperature and pourability at a low temperature, that is also extremely excellent in shear stability, and that can maintain lubricating oil performance over a long period of use.
  • it has high heat dissipation performance, and therefore can be suitably applied to cooling of an electric motor and lubrication of a gear in an electric vehicle.
  • lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle according to the present invention (hereinafter, also referred to simply as “lubricating oil composition”) will be described in detail below.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle is characterized in that the composition includes a lubricating base oil composed of a (A) mineral oil and/or a (B) synthetic oil, and an (C) ethylene- ⁇ -olefin copolymer, and has a kinematic viscosity at 100C within a specific range.
  • the (C) ethylene- ⁇ -olefin copolymer has the following characteristics (C1) to (C5).
  • the ethylene molar content rate of the (C) ethylene- ⁇ -olefin copolymer is usually 30 to 70 mol %, preferably 40 to 60 mol %, and particularly preferably 45 to 58 mol %. Outside this range of the ethylene molar content rate, crystals easily form from the ethylene- ⁇ -olefin copolymer at low temperature, a low temperature viscosity increases, and the fuel saving properties of the lubricating oil composition deteriorate.
  • the ethylene molar content rate of the (C) ethylene- ⁇ -olefin copolymer is measured by 13 C-NMR according to the method described in “Polymer Analysis Handbook” (Asakura Publishing Co., Ltd., P163-170).
  • a sample obtained by this method can also be measured by Fourier transform infrared spectroscopy (FT-IR) as a known sample.
  • FT-IR Fourier transform infrared spectroscopy
  • the kinematic viscosity of the (C) ethylene- ⁇ -olefin copolymer at 100° C. is 10 to 5,000 mm 2 /s, preferably 20 to 4,000 mm 2 /s, more preferably 25 to 3,500 mm 2 /s, still more preferably 30 to 3,000 mm 2 /s, and particularly preferably 35 to 2,500 mm 2 /s.
  • the shear stability of the lubricating oil composition decreases and fuel saving properties deteriorate. Below the above range, the low temperature pourability decreases, and fuel efficiency deteriorates significantly upon startup in a low temperature environment.
  • This value of the Hasen chromaticity is that measured by the method described in JIS K0071.
  • the Hasen chromaticity of the (C) ethylene- ⁇ -olefin copolymer is 30 or lower, preferably 0 to 30, more preferably 0 to 25, and still more preferably 0 to 20.
  • the Hasen chromaticity of the (C) ethylene- ⁇ -olefin copolymer exceeding this range means that an oxygen-containing functional group is excess in amount in a molecule of the (C) ethylene- ⁇ -olefin copolymer, whereby heat resistance and electric insulation of the resulting lubricating oil composition deteriorate.
  • the molecular weight distribution of the (C) ethylene- ⁇ -olefin copolymer is measured by gel permeation chromatography (GPC) according to the method described below and calculated as a ratio (Mw/Mn) of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn) obtained in terms of standard polystyrene.
  • Mw/Mn is 2.5 or less, preferably 1.0 to 2.5, more preferably 1.0 to 2.3, and still more preferably 1.0 to 2.2.
  • the molecular weight distribution exceeding this range means that low molecular weight components and high molecular weight components are included more, and containing low molecular weight components more increases a component that is easy to volatilize, increases the amount of evaporation loss in the lubricating oil composition, and lowers a thickening effect, and containing high molecular weight components more causes deterioration of shear stability and thermal stability of the lubricating oil composition.
  • the B value represented by the following formula [1] of the (C) ethylene- ⁇ -olefin copolymer is 1.1 or more, preferably 1.1 to 1.5, and more preferably 1.2 to 1.4.
  • the B value exceeding this range means that the alternating polymerization of ethylene or ⁇ -olefin in the (C) ethylene- ⁇ -olefin copolymer decreases, and the (C) ethylene- ⁇ -olefin copolymer crystallizes at low temperature, resulting in deterioration of the low temperature characteristics of the lubricating oil composition and significant deterioration of fuel saving properties.
  • P E represents a molar fraction of ethylene component
  • P O represents a molar fraction of ⁇ -olefin component
  • P OE represents a molar fraction of ethylene- ⁇ -olefin sequence in the total dyad sequence.
  • the B value is an index of randomness of a comonomer sequence distribution in a copolymer
  • P E , P O , and P OE in the above formula [1] can be determined by measuring 13 C-NMR spectra and based on known literature such as reports of J. C. Randall [Macromolecules, 15, 353 (1982)] and J. Ray et al. [Macromolecules, 10, 773 (1977)], and “Polymer Analysis Handbook” (published by Asakura Publishing Co, pp. 163-170).
  • the larger the B value the lower the pour point of the (C) ethylene- ⁇ -olefin copolymer and the more favorable the low temperature viscosity characteristics of the lubricating oil composition.
  • the specific measurement conditions of the B value are as described in Examples.
  • the (C) ethylene- ⁇ -olefin copolymer preferably further has at least one characteristic of (C6) to (C8)
  • This value of the thermal diffusivity at 50C is represented by the following formula by determining each of the thermal conductivity, specific heat, and density.
  • Thermal ⁇ diffusivity ⁇ ( m 2 / s ) [ Thermal ⁇ conductivity ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ] [ Specific ⁇ heat ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ] ⁇ [ Density ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ]
  • the thermal conductivity is measured at a test temperature of 50° C. in accordance with JIS R2616.
  • the specific heat is measured continuously under adiabatic conditions between 30° C. and 80° C. in an air atmosphere using a specific heat measuring apparatus (for example, specific heat measuring apparatus SH-3000 model manufactured by SHINKU-RIKO Inc.), and the specific heat at 50C is employed.
  • the density is measured at 50° C. in accordance with JIS K2249.
  • the thermal diffusivity of the (C) ethylene- ⁇ -olefin copolymer at 50° C. is preferably 8.5 ⁇ 10 ⁇ -5 to 9.8 ⁇ 10 ⁇ -5 m ⁇ 2/s, more preferably 8.8 ⁇ 10 ⁇ -5 to 9.6 ⁇ 10 ⁇ -5 m ⁇ 2/s, and still more preferably 9.0 ⁇ 10 ⁇ -5 to 9.4 ⁇ 10 ⁇ -5 m ⁇ 2/s.
  • the thermal diffusivity of the (C) ethylene- ⁇ -olefin copolymer at 50° C. is at or above the lower limit value described above, the heat generation in the motor is inhibited, and the lubricating oil composition has good heat resistance and electric insulation.
  • volume resistivity at 50C and 250 V is that in the case when measured at a test temperature of 50C and at 250 V by the method described in JIS C2101.
  • the volume resistivity of the (C) ethylene- ⁇ -olefin copolymer at 50C and 250 V is 1.0 ⁇ 10 ⁇ 15 to 1.0 ⁇ 10 ⁇ 17 ⁇ cm, preferably 2.0 ⁇ 10 ⁇ 15 to 9.0 ⁇ 10 ⁇ 16 ⁇ cm, and more preferably 3.0 ⁇ 10 ⁇ 15 to 8.0 ⁇ 10 ⁇ 16 ⁇ cm.
  • the volume resistivity of the (C) ethylene- ⁇ -olefin copolymer at 50° C. and 250 V is at or above the lower limit value described above, the lubricating oil composition has high electric insulation, and thus the safety of electric vehicles can be maintained.
  • (C8) A relative permittivity at 50° C. of 2.00 to 2.30 This value of the relative permittivity at 50C is that in the case when measured at a test temperature of 50° C. by the method described in JIS C2138.
  • the relative permittivity of the (C) ethylene-( ⁇ -olefin copolymer at 50C is 2.00 to 2.30, preferably 2.00 to 2.27, and more preferably 2.00 to 2.25.
  • the relative permittivity of the (C) ethylene- ⁇ -olefin copolymer at 50° C. is at or below the upper limit value described above, the lubricating oil composition has high electric insulation, and thus the safety of electric vehicles can be maintained.
  • the (C) ethylene- ⁇ -olefin copolymer more preferably further has at least one characteristic of (C9) and (C10).
  • (C9) A weight-average molecular weight of 1,000 to 30,000
  • the weight-average molecular weight (Mw) of the (C) ethylene- ⁇ -olefin copolymer is measured by gel permeation chromatography (GPC) according to the method described below and obtained in terms of standard polystyrene.
  • This weight-average molecular weight (Mw) is preferably 1,200 to 25,000, more preferably 1,400 to 20,000, and still more preferably 1,500 to 16,000.
  • the (C) ethylene- ⁇ -olefin copolymer with a weight-average molecular weight (Mw) of 1,000 or higher has a few components that are easy to volatilize, whereby the lubricating oil composition has less evaporation loss and is excellent in viscosity thickening effect and temperature viscosity characteristics, and the (C) ethylene- ⁇ -olefin copolymer having a Mw of 30,000 or lower allows the lubricating oil composition to have a low pour point, excellent shear stability and heat resistance.
  • Mw weight-average molecular weight
  • the (C) ethylene- ⁇ -olefin copolymer preferably has no melting point observed in differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • Tm melting point
  • ⁇ H heat of fusion
  • OH heat of fusion
  • DSC differential scanning calorimetry
  • the melting point (Tm) and heat of fusion ( ⁇ H) of the (C) ethylene- ⁇ -olefin copolymer are obtained by carrying out differential scanning calorimetry (DSC), and analyzing a DSC curve obtained when a specimen is cooled to ⁇ 100° C., and then raised to 150° C. at a rate of temperature rise of 10° C./min, referring to JIS K7121. If the melting point is not observed, no crystalline components are generated at a low temperature, thereby inhibiting a rise in low temperature viscosity, and the lubricating oil composition has excellent low temperature viscosity characteristics.
  • DSC differential scanning calorimetry
  • Examples of an ⁇ -olefin used in the (C) ethylene- ⁇ -olefin copolymer include linear or branched C3-C20 ⁇ -olefins 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.
  • linear or branched C3-C20 ⁇ -olefins 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-hex
  • the ⁇ -olefin is preferably a linear or branched C3-C10 ⁇ -olefin, more preferably propylene, 1-butene, 1-hexene, and 1-octene, and most preferably propylene from the standpoint of shear stability of the lubricating oil with the resulting copolymer.
  • These ⁇ -olefins can be used singly or in combinations of two or more thereof.
  • Polymerization can also proceed by coexisting in the reaction system at least one type of an optional monomer selected from the group consisting of a polar group-containing monomer, an aromatic vinyl compound, and a cyclic olefin.
  • the optional monomer can be used, for example, in an amount of 20 parts by mass or less and preferably 10 parts by mass or less, based on 100 parts by mass in total of ethylene and a C3-C20 ⁇ -olefin.
  • Examples of the polar group-containing monomer include ⁇ , ⁇ -unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, and maleic anhydride, and metal salts such as sodium salts thereof, ⁇ , ⁇ -unsaturated carboxylic 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 glycidyl compounds such as glycidyl acrylate and glycidyl methacrylate.
  • carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, and maleic anhydride
  • metal salts such as sodium salts thereof
  • ⁇ , ⁇ -unsaturated carboxylic esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate
  • aromatic vinyl compound examples include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, methoxystyrene, vinyl benzoate, vinyl methyl benzoate, vinyl benzyl acetate, hydroxystyrene, p-chlorostyrene, divinylbenzene, ⁇ -methylstyrene, allylbenzene, for example.
  • cyclic olefin examples include C3-C30 cyclic olefins such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, and tetracyclododecene and preferably C3-C20 cyclic olefins.
  • the origin of a monomer used for the (C) ethylene- ⁇ -olefin copolymer is not particularly limited, but for example, monomers derived from fossil fuel or monomers derived from biomass can be used, and these monomers may be used singly or in combinations of two or more thereof.
  • the (C) ethylene- ⁇ -olefin copolymer may be constituted solely with a monomer derived from fossil fuel, may be constituted solely with a monomer derived from biomass, or a monomer derived from fossil fuel and a monomer derived from biomass may be used in combination.
  • the fossil fuel is petroleum, coal, natural gas, shale gas, or a combination thereof.
  • the biomass is any renewable natural raw material and residues thereof, such as of plant origin or animal origin, including fungi, yeasts, algae, and bacteria.
  • the method for producing the (C) ethylene- ⁇ -olefin copolymer in the present invention is not particularly limited, and include methods such as those described in patent literature JPH2-1163B and JPH2-7998B wherein using a vanadium-based catalyst including a vanadium compound and an organoaluminum compound.
  • a method for producing a copolymer with high polymerization activity methods using a catalyst system composed of a metallocene compound such as zirconocene and organoaluminum oxy compounds (aluminoxanes) as described in patent literature JPS61-221207A, JPH7-121969B, and JP2796376B can be employed.
  • This method can reduce the chlorine content of the resulting copolymer and 2,1-insertion of propylene, which is more preferred.
  • the method by the vanadium-based catalyst uses more chlorine compounds as an auxiliary catalyst than the method using the metallocene-based catalyst, whereby a trace amount of chlorine may remain in the resulting the (C) ethylene- ⁇ -olefin copolymer.
  • the method using the metallocene-based catalyst leaves no residual chlorine substantially, eliminating the need to consider the possibility of corrosion of metal parts in machines, for example.
  • the chlorine content is preferably 100 ppm or less, more preferably 50 ppm or less, still 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 Examples.
  • the reduction of 2,1-insertion of propylene can further decrease the amount of ethylene sequence in a copolymer molecule and inhibit intramolecular crystallinity of ethylene, thereby enabling improvement on the viscosity/temperature characteristics and the low temperature viscosity characteristics of the lubricating oil composition.
  • an (C) ethylene- ⁇ -olefin copolymer having a favorable performance balance in terms of molecular weight control, molecular weight distribution, amorphous properties, and the B-value can be obtained.
  • the (C) ethylene- ⁇ -olefin copolymer can be produced by copolymerizing ethylene and a C3-C20 ⁇ -olefin in the presence of an olefin polymerization catalyst including a bridged metallocene compound (a) represented by the general formula [I] below, 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.
  • 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.
  • the bridged metallocene compound (a) is represented by the above formula [I]. Y, M, R 1 to R 14 , Q, n and j in formula [I] will be described below.
  • Y is a Group XIV atom, is, for example, a carbon atom, a silicon atom, a germanium atom, or a tin atom, and is preferably a carbon atom or a silicon atom, more preferably a carbon atom.
  • M is a titanium atom, a zirconium atom, or a hafnium atom, preferably a zirconium atom.
  • R 1 to R 12 are each an atom or a substituent selected from the group consisting of a hydrogen atom, a C1-C20 hydrocarbon group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom, and a halogen-containing group, and may be the same as or different from each other.
  • the substituents R 1 to R 12 that are adjacent to each other may also be bonded together to form a ring or may not be bonded to each other.
  • Examples of the C1-C20 hydrocarbon group include C1-C20 alkyl groups, C3-C20 cyclic saturated hydrocarbon groups, C2-C20 linear unsaturated hydrocarbon groups, C3-C20 cyclic unsaturated hydrocarbon groups, C1-C20 alkylene groups and C6-C20 arylene groups.
  • Examples of the C1-C20 alkyl groups include linear saturated hydrocarbon groups such as a methyl group, an ethyl group, a n-propyl group, an allyl group, a n-butyl group, a n-pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group and a n-decanyl group, and branched saturated hydrocarbon groups such as an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, a t-amyl group, a neopentyl group, a 3-methylpentyl group, a 1,1-diethylpropyl group, a 1,1-dimethylbutyl group, a 1-methyl-1-propylbutyl group, a 1,1-propylbut
  • Examples of the C3-C20 cyclic saturated hydrocarbon groups include cyclic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a norbornenyl group, a 1-adamantyl group and a 2-adamantyl group, and groups resulting from the substitution of cyclic saturated hydrocarbon groups with a C1-C17 hydrocarbon group in place of a hydrogen atom, such as a 3-methylcyclopentyl group, a 3-methylcyclohexyl group, a 4-methylcyclohexyl group, a 4-cyclohexylcyclohexyl group and a 4-phenylcyclohexyl group.
  • the number of carbon atoms in such a cyclic saturated hydrocarbon group is preferably 5 to 11.
  • Examples of the C2-C20 linear unsaturated hydrocarbon groups include alkenyl groups such as an ethenyl group (vinyl group), a 1-propenyl group, a 2-propenyl group (allyl group) and a 1-methylethenyl group (isopropenyl group), and alkynyl groups such as an ethynyl group, a 1-propynyl group and a 2-propynyl group (propargyl group).
  • the number of carbon atoms in such a linear unsaturated hydrocarbon group is preferably 2 to 4.
  • Examples of the C3-C20 cyclic unsaturated hydrocarbon groups include cyclic unsaturated hydrocarbon groups such as a cyclopentadienyl group, a norbornyl group, a phenyl group, a naphthyl group, an indenyl group, an azulenyl group, a phenanthryl group and an anthracenyl group, groups resulting from the substitution of cyclic unsaturated hydrocarbon groups with a C1-C15 hydrocarbon group in place of a hydrogen atom, such as a 3-methylphenyl group (m-tolyl group), a 4-methylphenyl group (p-tolyl group), a 4-ethylphenyl group, a 4-t-butylphenyl group, a 4-cyclohexylphenyl group, a biphenylyl group, a 3,4-dimethylphenyl group, a 3,5-dimethylphenyl group and a 2,4,6-trimethylphen
  • Examples of the C1-C20 alkylene groups include a methylene group, an ethylene group, a dimethylmethylene group (isopropylidene group), an ethylmethylene group, a methylethylene group and a n-propylene group.
  • the number of carbon atoms in such an alkylene group is preferably 1 to 6.
  • Examples of the C6-C20 arylene groups include an o-phenylene group, a m-phenylene group, a p-phenylene group and a 4,4′-biphenylylene group.
  • the number of carbon atoms in such an arylene group is preferably 6 to 12.
  • Examples of the silicon-containing group include groups resulting from the substitution of C1-C20 hydrocarbon groups with a silicon atom in place of a carbon atom, for example, alkylsilyl groups such as a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group and a triisopropylsilyl group, arylsilyl groups such as a dimethylphenylsilyl group, a methyldiphenylsilyl group and a t-butyldiphenylsilyl group, and a pentamethyldisilanyl group and a trimethylsilylmethyl group.
  • the number of carbon atoms in such an alkylsilyl group is preferably 1 to 10
  • the number of carbon atoms in such an arylsilyl group is preferably 6 to 18.
  • nitrogen-containing group examples include an amino group, groups resulting from the substitution of the above C1 to C20 hydrocarbon groups or silicon-containing groups with a nitrogen atom in place of a ⁇ CH— structural unit, groups resulting from the substitution of the above C1 to C20 hydrocarbon groups or silicon-containing groups with a nitrogen atom to which a C1 to C20 hydrocarbon group is bonded in place of a —CH 2 — structural unit, and groups resulting from the substitution of the above C1 to C20 hydrocarbon groups or silicon-containing groups with a nitrogen atom to which a C1 to C20 hydrocarbon group is bonded or a nitrile group in place of a —CH 3 structural unit, such as a dimethylamino group, a diethylamino group, an N-morpholinyl group, a dimethylaminomethyl group, a cyano group, a pyrrolidinyl group, a piperidinyl group, and a pyridinyl group, for example, and
  • oxygen-containing group examples include a hydroxide group, groups resulting from the substitution of the above C1 to C20 hydrocarbon groups, silicon-containing groups, or nitrogen-containing groups with an oxygen atom or a carbonyl group in place of a —CH 2 — structural unit, and groups resulting from the substitution of the above C1 to C20 hydrocarbon groups, silicon-containing groups, or nitrogen-containing groups with an oxygen atom to which a C1 to C20 hydrocarbon group is bonded in place of a —CH 3 structural unit, such as a methoxy group, an ethoxy group, a t-butoxy group, a phenoxy group, a trimethylsiloxy group, a methoxyethoxy group, a hydroxymethyl group, a methoxymethyl group, an ethoxymethyl group, t-butoxymethyl group, a 1-hydroxyethyl group, a 1-methoxyethyl group, a 1-ethoxyethyl group, a 2-hydroxyethyl group
  • halogen atom examples include Group XVII atoms such as fluorine, chlorine, bromine, and iodine.
  • halogen-containing group examples include groups resulting from the substitution of the above C1-C20 hydrocarbon groups, silicon-containing groups, nitrogen-containing groups, or oxygen-containing groups with a halogen atom in place of a hydrogen atom, such as a trifluoromethyl group, a tribromomethyl group, a pentafluoroethyl group and a pentafluorophenyl group.
  • Q is selected as a combination of the same or different members of a halogen atom, a C1-C20 hydrocarbon group, an anion ligand, and a neutral ligand capable of coordinating to a lone electron pair.
  • the details of the halogen atom and the C1-C20 hydrocarbon group are as described above.
  • Q is the halogen atom
  • Q is preferably a chlorine atom.
  • the number of carbon atoms in the hydrocarbon group is preferably 1 to 7.
  • anion ligand examples include alkoxy groups such as a methoxy group, a t-butoxy group, and a phenoxy group, carboxylate groups such as acetate and benzoate, and sulfonate groups such as methylate and tosylate.
  • Examples of the neutral ligand capable of coordinating to a lone electron pair include phosphororganic compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine and diphenylmethylphosphine, and ether compounds such as tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxyethane.
  • phosphororganic compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine and diphenylmethylphosphine
  • ether compounds such as tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxyethane.
  • 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 still more preferably 1.
  • R 13 and R 14 are each an atom or a substituent selected from the group consisting of a hydrogen atom, a C1 to C20 hydrocarbon group, an aryl group, a substituted aryl group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group, and R 13 and R 14 may be the same as or different from each other. Moreover, R 13 and R 14 may be bonded to each other to form a ring or may not be bonded to each other.
  • Examples of the aryl group are partially overlapped with examples of the C3-C20 cyclic unsaturated hydrocarbon groups, and include aromatic compound-derived substituents such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthracenyl group, a phenanthrenyl group, a tetracenyl group, a chrysenyl group, a pyrenyl group, an indenyl group, an azulenyl group, a pyrrolyl group, a pyridyl group, a furanyl group and a thiophenyl group.
  • the aryl group is preferably a phenyl group or a 2-naphthyl group.
  • aromatic compound examples include aromatic hydrocarbon and heterocyclic aromatic compounds, such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, pyrene, indene, azulene, pyrrole, pyridine, furan and thiophene.
  • aromatic hydrocarbon and heterocyclic aromatic compounds such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, pyrene, indene, azulene, pyrrole, pyridine, furan and thiophene.
  • Examples of such a substituted aryl group are partially overlapped with examples of the C3-C20 cyclic unsaturated hydrocarbon groups, and include groups resulting from the substitution of the aryl group with at least one substituent selected from the group consisting of a C1-C20 hydrocarbon group, an aryl group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group in place of one or more hydrogen atoms, and specifically 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-aminophenyl group, a 4-(dimethylamino
  • bridged metallocene compound (a) represented by the above formula [I] n is preferably 1.
  • bridged metallocene compound ( ⁇ -1) is represented by the following general formula [II]:
  • the bridged metallocene compound ( ⁇ -1) allows production steps to be simplified and production cost to be lowered, compared to a compound in which n in the above formula [I] is an integer of 2 to 4, and furthermore, use of this bridged metallocene compound ( ⁇ -1) provides an advantage of production cost of the (C) ethylene- ⁇ -olefin copolymer being lowered.
  • bridged metallocene compound ( ⁇ -1) represented by the above formula [II]
  • R 1 , R 2 , R 3 and R 4 are preferably all hydrogen.
  • Such a bridged metallocene compound (hereinafter also referred to as “bridged metallocene compound ( ⁇ -2)”) is represented by the following general formula [III].
  • the bridged metallocene compound ( ⁇ -2) allows production steps to be simplified and production cost to be lowered, compared to the compound in which any one or more of R 1 , R 2 , R 3 , and R 4 in the above formula [I] is substituted with a substituent other than a hydrogen atom, and furthermore, use of this bridged metallocene compound ( ⁇ -2) provides an advantage of the production cost of the (C) ethylene- ⁇ -olefin copolymer being lowered.
  • high temperature polymerization has been generally known to decrease randomness of the (C) ethylene- ⁇ -olefin copolymer, however, in a case in which ethylene and one or more types of monomers selected from C3-C20 ⁇ -olefins are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound ( ⁇ -2), an advantage of high randomness of the obtained (C) ethylene- ⁇ -olefin copolymer even in high temperature polymerization, is obtained.
  • either one of R 13 and R 14 is preferably an aryl group or a substituted aryl group.
  • Such a bridged metallocene compound ( ⁇ -3) provides an advantage that the amount of double bonds in the generated (C) ethylene- ⁇ -olefin copolymer is smaller than when both R 13 and R 14 are substituents other than aryl groups and substituted aryl groups.
  • R 13 and R 14 is an aryl group or a substituted aryl group and the other is a C1-C20 alkyl group, and particularly preferably either one of R 13 and R 14 is an aryl group or a substituted aryl group and the other is methyl group.
  • bridged metallocene compound ( ⁇ -4) has an excellent balance between the amount of double bonds and polymerization activity in an (C) ethylene- ⁇ -olefin copolymer formed, compared to the case where both RU and R 14 are both aryl groups or substituted aryl groups, and use of this bridged metallocene compound provides an advantage of the production cost of the (C) ethylene- ⁇ -olefin copolymer being lowered.
  • the bridged metallocene compound ( ⁇ -4) is used to produce the (C) ethylene- ⁇ -olefin copolymer in the present invention, the amount of hydrogen introduced in the polymerization reactor is reduced and the polymerization activity is improved, compared to the case of using the above bridged metallocene compound ( ⁇ -3), whereby an advantage of the production cost of the (C) ethylene- ⁇ -olefin copolymer being reduced is obtained.
  • R 6 and R 11 are preferably a C1-C20 alkyl group or a C1-C20 alkylene group, which may be bonded to an adjacent substituent to form a ring.
  • Such a bridged metallocene compound (hereinafter referred to as a “bridged metallocene compound ( ⁇ -5)”) simplifies the production process more and further reduces the production cost, compared to a compound in which R 6 and R 1 are substituted with substituents other than the C1-C20 alkyl group or the C1-C20 alkylene group, and furthermore use of this bridged metallocene compound ( ⁇ -5) provides an advantage of the production cost of the (C) ethylene- ⁇ -olefin copolymer being reduced.
  • M is preferably a zirconium atom.
  • bridged metallocene compound (a) examples include
  • bridged metallocene compound (a) examples include compounds resulting from the substitution of the above compounds with a hafnium atom in please of a zirconium atom or with a methyl group in place of a chloro ligand, but the bridged metallocene compound (a) is not limited thereto.
  • ⁇ 5 -tetramethyloctahydrodibenzofluorenyl and ⁇ 5 -octamethyloctahydrodibenzofluorenyl as constituent moieties of the bridged metallocene compound (a) exemplified, respectively represent a 4,4,7,7-tetramethyl-(5a, 5b, 11a, 12,12 ⁇ - ⁇ 5 )-1,2,3,4,7,8,9,10-octahydrodibenzo[b,H]fluorenyl group and a 1,1,4,4,7,7,10,10-octamethyl-(5a,5b,11a,12,12 ⁇ - ⁇ 5 )-1,2,3,4,7,8,9,10-octahydrodibenzo[b,H]fluorenyl group.
  • the olefin polymerization catalyst includes the above bridged metallocene compound (a) 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.
  • organometallic compound (b-1) specifically, the following organometallic compounds of Groups I and II and Groups XII and XIII of the periodic table, are used.
  • a compound analogous to those represented by the above general formula R a m Al(OR b ) n H p X q can also be used, and examples thereof include an organoaluminum compound in which two or more aluminum compounds are bonded via a nitrogen atom.
  • organoaluminum compound in which two or more aluminum compounds are bonded via a nitrogen atom.
  • Specific examples of such a compound include (C 2 H 5 ) 2 AlN(C 2 H 5 )Al(C 2 H 5 )—, for example.
  • (b-1b) A complex alkylated compound of a Group I metal of the periodic table and aluminum, represented by the general formula M 2 AlR a 4 wherein in the formula, M 2 represents Li, Na or K, and R a represents a C1-C15 hydrocarbon group, preferably a C1-C4 hydrocarbon group.
  • Examples of such a compound include LiAl(C 2 H 5 ) 4 and LiAl(C 7 H 15 ) 4 , for example.
  • R a R b M 3 A dialkylated compound of a Group II or Group XII metal of the periodic table, represented by the general formula R a R b M 3 wherein in the formula, R a and R b may be the same as or different from each other and represent a C1-C15 hydrocarbon group, preferably a C 1 -C 4 hydrocarbon group, and M3 is Mg, Zn or Cd.
  • organoaluminum oxy compound (b-2) conventionally known aluminoxanes can be used as they are. Specific examples thereof include the compound represented by the following general formula [IV] and the compound represented by the following general formula [V].
  • R is a C1-C10 hydrocarbon group and n is an integer of 2 or more.
  • methylaluminoxane is utilized in which R is a methyl group and n is 3 or more, preferably 10 or more.
  • An organoaluminum compound is allowed to be slightly incorporated in such aluminoxane.
  • a benzene-insoluble organoaluminum oxy compound exemplified in patent literature JP H2-78687A can also be applied.
  • An organoaluminum oxy compound described in patent literature JP H2-167305A, or aluminoxane having two or more alkyl groups, described in patent literature JP H2-24701A and JP H3-103407A, can also be suitably utilized.
  • the “benzene-insoluble organoaluminum oxy compound” that may be used in the present invention is a compound that usually contains 10% or less, preferably 51 or less, particularly preferably 21 or less of an A1 component to be dissolved in benzene at 60° C., in terms of A1 atom, and that is insoluble or hardly soluble in benzene.
  • organoaluminum oxy compound (b-2) can also include a modified methylaluminoxane represented by the following general formula [VI], for example.
  • R is a C1-C10 hydrocarbon group, and m and n each independently represent an integer of 2 or more.
  • This modified methylaluminoxane is prepared by using trimethylaluminum and alkylaluminum other than trimethylaluminum.
  • a compound is commonly referred to as MMAO.
  • MMAO can be prepared by the methods described in patent literature U.S. Pat. Nos. 4,960,878 and 5,041,584.
  • a compound prepared by using trimethylaluminum and triisobutylaluminum, is commercially available from Tosoh-Finechem Corporation, for example, under the names MMAO and TMAO wherein R is an isobutyl group.
  • MMAO is aluminoxane with improved solubility in various solvents and storage stability, and is specifically soluble in an aliphatic hydrocarbon or an alicyclic hydrocarbon, unlike the compounds that are insoluble or difficult to be soluble in benzene, among the compounds represented by the above formula [IV] and those represented by the above formula [V].
  • organoaluminum oxy compound (b-2) can also include an organoaluminum oxy compound containing boron, represented by the following general formula [VII].
  • R C represents a C1-C10 hydrocarbon group.
  • R 4 may be the same as or different from each other and represents a hydrogen atom, a halogen atom or a C1-C10 hydrocarbon group.
  • Examples of the compound (b-3) that reacts with the bridged metallocene compound (a) to form an ionic pair include Lewis acids, ionic compounds, borane compounds and carborane compounds, for example, which are described in patent literature JPH1-501950A, JPH1-502036A, JPH3-179005A, JPH3-179006A, JPH3-207703A, JPH3-207704A, U.S. Pat. No. 5,321,106, for example. Examples thereof can further include heteropoly compounds and isopoly compounds.
  • the ionized ionic compound preferably used in the present invention is the boron compound represented by the following general formula [VIII].
  • examples of R e+ include H + , a carbenium cation, an oxonium cation, an ammonium cation, a phosphonium cation, a cycloheptyltrienyl cation, and a ferrocenium cation with transition metal, for example.
  • R f to R 1 may be the same as or different from each other and are substituents selected from C1-C20 hydrocarbon groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups and R f to R l are preferably substituted aryl groups.
  • carbenium cation examples include tri-substituted carbenium cations such as triphenylcarbenium cation, tris(4-methylphenyl)carbenium cation and tris(3,5-dimethylphenyl) carbenium cation.
  • ammonium cation examples 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.
  • trialkyl-substituted ammonium cations such as trimethylammonium cation, triethylammonium cation, tri(n-propyl)ammoni
  • phosphonium cation examples include triarylphosphonium cations such as triphenylphosphonium cation, tris(4-methylphenyl)phosphonium cation and tris(3,5-dimethylphenyl)phosphonium cation.
  • a carbenium cation and an ammonium cation is preferred among the above specific examples, and particularly a triphenylcarbenium cation, a N,N-dimethylanilinium cation and a N,N-diethylanilinium cation are preferred.
  • Examples of compounds containing the carbenium cation as the ionized ionic compounds preferably used in the present invention 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.
  • Examples of compounds containing the trialkyl-substituted ammonium cation as the ionized ionic compounds preferably used in the present invention 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
  • Examples of compounds containing a N,N-dialkylanilinium cation as the ionized ionic compounds preferably used in the present invention 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, N,N-2,4,6-pentamethylanilinium
  • Examples of compounds containing the dialkylammonium cation as the ionized ionic compounds preferably used in the present invention include di-n-propylammonium tetrakis(pentafluorophenyl)borate and dicyclohexylammonium tetraphenylborate.
  • the above ionic compound (b-3) may be used singly or combined for use with two or more types thereof.
  • organometallic compound (b-1) trimethylaluminum, triethylaluminum, and triisobutylaluminum, which are readily available as commercial products, are preferred. Of these, triisobutylaluminum is particularly preferred for its handleability.
  • organoaluminum oxy compounds (b-2) methylaluminoxane that is readily available as a commercial product and MMAO prepared with trimethylaluminum and triisobutylaluminum are preferred. Of these, MMAO is particularly preferred because of its improved solubility in various solvents and storage stability.
  • triphenylcarbenium tetrakis(pentafluozophenyl)borate and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate are preferred because they are readily available as commercial products and significantly contribute to polymerization activity.
  • 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 polymerization activity.
  • a carrier (c) may be used as a constituent of the olefin polymerization catalyst, if necessary.
  • the carrier (c) that may be used in the present invention is an inorganic or organic compound, which is a granular or particulate solid.
  • the inorganic compound is preferably a porous oxide, an inorganic chloride, clay, a clay mineral or an ion-exchangeable layered compound.
  • porous oxides specifically SiO 2 , Al 2 O 3 , MgO, ZrO, TiO 2 , B 2 O 3 , CaO, ZnO, BaO, and ThO 2 , for example, or composites or mixtures containing these materials, such as natural or synthetic zeolite, SiO 2 —MgO, SiO 2 —Al 2 O 3 , SiO 2 —TiO 2 , SiO 2 —V 2 O 5 , SiO 2 —Cr 2 O 3 , SiO 2 —TiO 2 —MgO, for example, can be used. Of these, those with SiO 2 and/or Al 2 O 3 as major components are preferred.
  • the carrier preferably used in the present invention has a particle size of 0.5 to 300 ⁇ m, preferably 1.0 to 200 ⁇ m, a specific surface area in a range of 50 to 1000 m 2 /g, preferably 100 to 700 m 2 /g, and a pore volume in a range of 0.3 to 3.0 cm 3 /g.
  • a carrier is, if necessary, fired at 100 to 1000° C., preferably 150 to 700° C., and then used.
  • the inorganic chlorides that are MgCl 2 , MgBr 2 , MnCl 2 , and MnBr 2 , for example, are used.
  • the inorganic chloride may be used as it is, or may be pulverized by a ball mill or a vibrating mill, and then used.
  • the inorganic chloride which is dissolved in a solvent such as an alcohol and then precipitated in the form of fine particles by a precipitating agent, may also be used.
  • Clay is usually composed of clay minerals as a main component.
  • the ion-exchangeable layered compound is a compound having a crystal structure in which surfaces configured are mutually stacked in parallel by a weak force with, for example, an ionic bond, and includes an exchangeable ion.
  • Most clay mineral corresponds to such an ion-exchangeable layered compound.
  • Such clay, clay mineral, and ion-exchangeable layered compounds here used are not limited to natural products, and can also be artificially synthesized products.
  • Examples of the clay, clay mineral, or ion-exchangeable layered compound include clay, clay mineral, and also ion crystalline compounds with layered crystal structures such as hexagonal fine packing type, antimony type, CdCl 2 type, and CdIL type, for example.
  • clay and clay mineral examples include kaolin, bentonite, kibushi clay, gairome clay, allophane, hisingerite, pyrophyllite, micas, montmorillonites, vermiculite, chlorite rocks, parigorskite, kaolinite, nacrite, dickite, and haloysite, for example, and examples of the ion-exchangeable layered compounds include crystalline acidic salts of polyvalent metals such as ⁇ -Zr(HAsO 4 ) 2 ⁇ H 2 O, ⁇ -Zr(HPO 4 ) 2 , ⁇ -Zr(KPO 4 ) 2 ⁇ 3H 2 O, ⁇ -Ti(HPO 4 ) 2 , ⁇ -Ti(HAsO 4 ) 2 ⁇ H 2 O, ⁇ -Sn(HPO 4 ) 2 ⁇ H 2 O, ⁇ -Zr(HPO 4 ) 2 , ⁇ -Ti(HPO 4 ) 2 , and
  • the clay and the clay mineral for use in the present invention are also preferably subjected to a chemical treatment.
  • the chemical treatment here used can be any treatment such as a surface treatment for removal of impurities attached to a surface, or a treatment having an effect on the crystal structure of the clay.
  • Specific examples of the chemical treatment include an acid treatment, an alkali treatment, a salt treatment and an organic substance treatment.
  • the ion-exchangeable layered compound may be a layered compound where a space between layers is enlarged by exchanging an exchangeable ion in the space between layers with another large and bulky ion by means of ion exchangeability.
  • a bulky ion serves as a shore supporting a layered structure, and is usually referred to as pillar.
  • intercalation introduction of another substance (guest compound) into the space between layers in the layered compound.
  • the guest compound examples include cationic inorganic compounds such as TiCl 4 and ZrCl 4 , metal alkoxides such as Ti(OR) 4 , Zr(OR) 4 , PO(OR) 3 , and B(OR) 3 (R is a hydrocarbon group, for example.), and metal hydroxide ions such as [A 13 O 4 (OH) 24 ] 7+ , [Zr 4 (OH) 14 ] 2+ , and [Fe 3 O(OCOCH 3 ) 6 ] + .
  • cationic inorganic compounds such as TiCl 4 and ZrCl 4
  • metal alkoxides such as Ti(OR) 4 , Zr(OR) 4 , PO(OR) 3 , and B(OR) 3 (R is a hydrocarbon group, for example.
  • R is a hydrocarbon group, for example.
  • metal hydroxide ions such as [A 13 O 4 (OH) 24 ] 7+ , [Zr 4 (OH) 14 ] 2+
  • a polymerization product obtained by hydrolytic polycondensation of metal alkoxides such as Si(OR) 4 , Al(OR) 3 , and Ge(OR) 4 (R is a hydrocarbon group, for example.), or a colloidal inorganic compound such as SiO 3 can be co-present.
  • the pillar include oxide generated by intercalation of the metal hydroxide ion into the space between layers and then heating and dehydration.
  • the clay or the clay mineral is preferable, and montmorillonite, vermiculite, pectolite, tainiolite and synthetic mica are particularly preferable.
  • Examples of the organic compound as the carrier (c) include a granular or particulate solid with a particle size in a range of 0.5 to 300 ⁇ m.
  • Specific examples include a (co)polymer generated with as a main component a C2-C14 ⁇ -olefin such as ethylene, propylene, 1-butene or 4-methyl-1-pentene, a (co)polymer generated with vinylcyclohexane or styrene as a main component, and modified products thereof.
  • a polymerization method using an olefin polymerization catalyst capable of producing the (C) ethylene- ⁇ -olefin copolymer with high randomness enables high temperature polymerization.
  • the use of the olefin polymerization catalyst can inhibit decrease in randomness of the (C) ethylene- ⁇ -olefin copolymer formed upon the high temperature polymerization.
  • the viscosity of the polymerization solution containing the (C) ethylene- ⁇ -olefin copolymer formed decreases at high temperatures, whereby a concentration of the (C) ethylene- ⁇ -olefin copolymer in a polymerizer can be increased compared to that of low temperature polymerization, resulting in higher productivity per unit of polymerizer.
  • Copolymerization of ethylene and ⁇ -olefin in the present invention can be carried out by either liquid-phase polymerization methods such as solution polymerization and suspension polymerization (slurry polymerization) or by gas-phase polymerization methods, however, the solution polymerization is particularly preferred from the viewpoint of maximizing the effects of the present invention in such a manner.
  • a method of use and order of addition of each component of the olefin polymerization catalyst may be arbitrarily selected. At least two or more components in the catalyst may be contacted with each other in advance.
  • the bridged metallocene compound (a) (hereinafter also referred to as “component (a)”) is usually used in an amount of 1 ⁇ 10 ⁇ 9 to 1 ⁇ 10 ⁇ 1 moles and preferably 1 ⁇ 10 ⁇ 8 to 1 ⁇ 10 ⁇ 2 moles per liter of reaction volume.
  • the organometallic compound (b-1) (hereinafter also referred to as “component (b-1)”) is used in an amount such that a molar ratio of the component (b-1) to a transition metal atom (M) in the component (a) [(b-1)/M] is usually 0.01 to 50,000 and preferably 0.05 to 10,000.
  • the organoaluminum oxy compound (b-2) (hereinafter also referred to as “component (b-2)”) is used in an amount such that a molar ratio of an aluminum atom in the component (b-2) to a transition metal atom (M) in the component (a) [(b-2)/M] is usually 10 to 5,000 and preferably 20 to 2,000.
  • the ionic compound (b-3) (hereinafter also referred to as “component (b-3)”) is used in an amount such that a molar ratio of the component (b-3) to a transition metal atom (M) in the component (a) [(b-3)/M] is usually 1 to 10,000 and preferably 1 to 5,000.
  • the polymerization temperature is usually ⁇ 50° C. to 300° C., preferably 30 to 250° C., more preferably 100C to 250° C., and still more preferably 130° C. to 200° C. As the temperature in the polymerization temperature region in the above range is higher, the solution viscosity during polymerization is lower, and removal of heat of polymerization is also easier.
  • the polymerization pressure is usually ordinary pressure to 10 MPa-gauge pressure (MPa-G), preferably ordinary pressure to 8 MPa-G.
  • the polymerization reaction can be carried out in any method of batchwise, semi-continuous, and continuous methods. Such polymerization can also be continuously carried out in two or more polymerization instruments different in reaction conditions.
  • the molecular weight of the resulting copolymer can be regulated by the changes in hydrogen concentration and polymerization temperature in a polymerization system. Furthermore, the molecular weight can be adjusted according to the amount of component (b) used. In the case of addition of hydrogen, the amount added is properly about 0.001 to 5,000 NL per kg of the copolymer.
  • the polymerization solvent for use in a liquid phase polymerization method is usually an inert hydrocarbon solvent, and is preferably a saturated hydrocarbon having a boiling point of 50C to 200C under ordinary pressure.
  • Specific examples of the polymerization solvent include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane and kerosene oil, and alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane, and particularly preferably include hexane, heptane, octane, decane and cyclohexane.
  • the ⁇ -olefin to be polymerized by itself, can also be used as the polymerization solvent. While an aromatic hydrocarbon such as benzene, toluene or xylene, or a halogenated hydrocarbon such as ethylene chloride, chlorobenzene or dichloromethane can also be used as the polymerization solvent, use thereof is not preferable in terms of a reduction in load on the environment and in terms of minimization of the influence on human health.
  • the kinematic viscosity at 100C of the olefin polymer depends on the molecular weight of the polymer. In other words, a high molecular weight leads to a high viscosity and a low molecular weight leads to a low viscosity, and thus the kinematic viscosity at 100C is adjusted by the above molecular weight adjustment.
  • a low molecular weight component in a polymer obtained can be removed by a conventionally known method such as distillation under reduced pressure, to thereby allow for adjustment of the molecular weight distribution (Mw/Mn) of the polymer obtained.
  • the polymer obtained may be further subjected to hydrogen addition (hereinafter, also referred to as hydrogenation.) by a conventionally known method. If the number of double bonds in the polymer obtained by such hydrogenation is reduced, oxidation stability and heat resistance are enhanced.
  • the resulting (C) ethylene- ⁇ -olefin copolymer may be used singly or combined for use with two or more types of those with different molecular weights or with different monomer compositions.
  • the (C) ethylene- ⁇ -olefin copolymer may undergo graft-modification in its functional group and may further undergo secondary modification.
  • examples thereof include, for example, the method described in patent literature JPS61-126120A and JP2593264B, for example, and examples of the secondary modification include the method described in patent literature JP2008-508402A, for example.
  • the (A) mineral oil has the following characteristics (A1) to (A3).
  • the kinematic viscosity of (A) mineral oil at 100° C. is 2 to 8 mm 2 /s, preferably 2.3 to 5.5 mm 2 /s, and more preferably 2.8 to 5 mm 2 /s. Within this range of the kinematic viscosity at 100° C., the lubricating oil composition of the present invention is excellent in terms of a balance of volatility and temperature viscosity characteristics.
  • the viscosity index of (A) mineral oil is 105 or more, preferably 110 or more, and still more preferably 115 or more. Within this range of the viscosity index, the lubricating oil composition of the present invention is excellent in temperature viscosity characteristics.
  • the pour point of (A) mineral oil is ⁇ 5° C. or lower, more preferably ⁇ 10° C. or lower, and still more preferably ⁇ 12° C. or lower. Within this range of the pour point, the lubricating oil composition of the present invention is excellent in low temperature viscosity characteristics.
  • the (B) synthetic oil has the following characteristics (B1) to (B3).
  • the kinematic viscosity of (B) synthetic oil at 100° C. is 1 to 9 mm 2 /s, preferably 1.5 to 7 mm 2 /s, and more preferably 1.8 to 5 mm 2 /s. Within this range of the kinematic viscosity at 100° C., the lubricating oil composition of the present invention is excellent in terms of a balance of volatility and temperature viscosity characteristics.
  • the viscosity index of (B) synthetic oil is 110 or more, preferably 115 or more, and more preferably 120 or more. Within this range of the viscosity index, the lubricating oil composition of the present invention is excellent in temperature viscosity characteristics.
  • the pour point of (B) synthetic oil is ⁇ 30° C. or lower, preferably ⁇ 40° C. or lower, more preferably ⁇ 50° C. or lower, and still more preferably ⁇ 60° C. or lower. Within this range of the pour point, the lubricating oil composition of the present invention is excellent in low temperature viscosity characteristics.
  • the lubricating base oil used in the present invention is different in its performance and quality, such as viscosity characteristics, heat resistance, and oxidation stability, depending on its production methods and refining methods, for example.
  • the lubricating base oil is generally classified into mineral oil and synthetic oil. In the American Petroleum Institute (API), lubricating base oil is also classified into five categories: Group I, II, III, IV, and V. These API categories are defined in API Publication 1509, 15th Edition, Appendix E, April 2002 and are as shown in Table 1.
  • the (A) mineral oil can be any of Groups I to III in the API categories
  • the (B) synthetic oil can be any of Groups IV and V in the API categories. The details will be described below:
  • the (A) mineral oil belongs to Groups I to III in the API categories described above.
  • the quality of (A) mineral oil is as described above, and mineral oil of the respective qualities described above will be obtained by refining methods.
  • specific examples of the mineral oil include a lubricating base oil obtained by a process in which the lubricating oil fraction obtained by vacuum distillation of the atmospheric residual oil obtained by atmospheric distillation of crude oil is refined by carrying out one or more processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, and hydrogenation refining or a lubricating base oil such as wax isomerized mineral oil.
  • Gas-to-liquid (GTL) base oil obtained by the Fischer-Tropsch method is also suitable base oil that can be used as Group III mineral oil.
  • Such GTL base oil may be treated as Group III+lubricating base oil and is described, for example, in Patent Literatures of EP0776959, EP0668342, WO97/21788, WO00/15736, WO00/14188, WO00/14187, WO00/14183, WO00/14179, WO00/08115, WO99/41332, EP1029029, WO01/18156 and WO01/57166.
  • the (B) synthetic oil belongs to Group IV or Group V in the API categories described above.
  • the poly- ⁇ -olefin belonging to Group IV can be obtained by acid catalyzed oligomerization using boron trifluoride, a chromic acid catalyst, for example, as described in patent literature U.S. Pat. Nos. 3,382,291, 3,763,244, 5,171,908, 3,780,128, 4,032,591, JPH1-163136A, U.S. Pat. Nos. 4,967,032, and 4,926,004.
  • the poly- ⁇ -olefin can also be obtained by methods, for example, such as employing a catalyst system using complexes of transition metal such as zirconium, titanium, and hafnium, including a metallocene compound as described in patent literature JPS63-037102A, JP2005-200447A, JP2005-200448A, JP2009-503147A, and JP2009-501836A.
  • a lubricating oil composition extremely excellent in temperature viscosity characteristics and low temperature viscosity characteristics, and even heat resistance, can be obtained.
  • the poly- ⁇ -olefin is also industrially available and a poly- ⁇ -olefin with 100C kinematic viscosity of 2 mm 2 /s to 300 mm 2 /s is commercially available. Among them, use of poly- ⁇ -olefin with 2 to 6 mm 2 /s is preferred in terms of providing a lubricating oil composition excellent in temperature viscosity characteristics. Examples thereof include NEXBASE 2000 series manufactured by NESTE Corporation, Spectrasyn series manufactured by ExxonMobil Chemical Company, Durasyn series manufactured by Ineos Oligmers, and Synfluid series manufactured by Chevron Phillips Chemical Co LLC., for example.
  • Examples of synthetic oil belonging to Group V include, for example, alkyl benzenes, alkyl naphthalenes, isobutene oligomers or their hydrides, paraffins, a polyoxyalkylene glycol, a dialkyl diphenyl ether, and polyphenyl ether and esters.
  • alkylbenzenes and alkylnaphthalenes are typically a dialkylbenzene or a dialkylnaphthalene with a C6-C14 alkyl chain length, and such alkylbenzenes or alkylnaphthalenes are produced by the Friedel-Craft alkylation reaction of benzene or naphthalene with an olefin.
  • An alkylated olefin used in production of alkylbenzenes or alkylnaphthalenes may be a linear or branched olefin or combinations thereof.
  • a fatty acid ester is preferred as the esters in terms of compatibility with the (C) ethylene- ⁇ -olefin copolymer.
  • the fatty acid ester is not particularly limited, but examples thereof include the following fatty acid esters composed solely of carbon, oxygen, and hydrogen, such as a monoester produced from a monobasic acid and an alcohol; a diester produced from a dibasic acid and an alcohol, or from a diol and a monobasic acid or an acid mixture; a polyol ester produced by reacting a diol, a triol (for example, trimethylolpropane), a tetraol (for example, pentaerythritol), or a hexanol (for example, dipentaerythritol), for example, with a monobasic acid or an acid mixture.
  • a triol for example, trimethylolpropane
  • a tetraol for example, pentaerythri
  • esters examples 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, and pentaerythritol tetraheptanoate, for example.
  • an alcohol with two or more functional hydroxyl groups is preferred as the alcohol moiety constituting the ester, and a C8 or more fatty acid is preferred as the fatty acid moiety.
  • a C20 or less fatty acid that is readily industrially available is more preferred in terms of production cost.
  • the fatty acid constituting the ester may be of one type, and use of a fatty acid ester produced by using a mixture of two or more types of acids allows an effect of the present invention to be sufficiently exhibited.
  • the fatty acid ester include a trimethylolpropane lauric acid-stearic acid mixed triester and diisodecyl adipate, for example, which are preferred due to compatibility between a saturated hydrocarbon component such as the (C) ethylene- ⁇ -olefin copolymer and stabilizers such as an antioxidant, a corrosion inhibitor, an antiwear agent, a friction modifier, a pour point depressant, a rust inhibitor and an antifoaming agent, which have a polar group as described below.
  • a saturated hydrocarbon component such as the (C) ethylene- ⁇ -olefin copolymer
  • stabilizers such as an antioxidant, a corrosion inhibitor, an antiwear agent, a friction modifier, a pour point depressant, a rust inhibitor and an antifoaming agent, which have a polar group as described below.
  • the lubricating oil composition of the present invention preferably contains a fatty acid ester in an amount of 1 to 20% by mass based on the total lubricating oil composition of 100% by mass. Containing 1. by mass or more of the fatty acid ester renders favorable compatibility with lubricating oil sealing materials such as resins and elastomers in an electric vehicle. Specifically, swelling of the lubricating oil sealing material can be inhibited. From the viewpoint of oxidation stability or heat resistance, the amount of ester is preferably 20% by mass or less.
  • the mineral oil is contained in the lubricating oil composition, the fatty acid ester is not necessarily required because the mineral oil itself has an effect of inhibiting swelling of the lubricating oil sealing material.
  • the (B) synthetic oil is preferred compared to the (A) mineral oil in terms of superior heat resistance and temperature viscosity characteristics.
  • one type of (A) mineral oil or (B) synthetic oil may be used singly as the lubricating base oil, or an arbitrary mixture of two or more types of lubricating oil selected from among the (A) mineral oil and the (B) synthetic oil, for example, may be used.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle contains the (A) mineral oil and/or (B) synthetic oil, and the (C) ethylene- ⁇ -olefin copolymer, and has the following characteristic (D1).
  • a kinematic viscosity at 100C is 4 to 10 nm/s.
  • This kinematic viscosity at 100° C. is 4 to 10 mm 2 /s, preferably 4 to 7.5 mm 2 /s, more preferably 4 to 6.5 mm 2 /s, and still more preferably 4.2 to 6 mm 2 /s.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle according to the present invention preferably further has characteristics (D2) and (D3).
  • This viscosity index (the viscosity index measured according to the method described in JIS K2283) is preferably 110 or more, more preferably 120 or more, still more preferably 125 or more, and particularly preferably 130 or more. Within this range of the viscosity index, the lubricating oil composition has excellent temperature viscosity characteristics and can achieve both the aforementioned energy saving and lubricity over a wide range of temperatures.
  • the pour point (the pour point measured according to the method described in ASTM D97) of the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle according to the present invention is preferably ⁇ 40° C. or lower, more preferably ⁇ 45° C. or lower, and still more preferably ⁇ 50° C. or lower.
  • a low pour point indicates that the lubricating oil composition has excellent low temperature characteristics.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle of the present invention preferably contains the lubricating base oil including the (A) mineral oil and/or (B) synthetic oil at a proportion of 90 to 99Z by mass, and the (C) ethylene- ⁇ -olefin copolymer at a proportion of 10 to 1f by mass.
  • the total of the lubricating base oil and the (C) ethylene- ⁇ -olefin copolymer is taken as 100% by mass.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle of the present invention preferably contains the lubricating base oil at a proportion of 92 to 99% by mass and the (C) ethylene- ⁇ -olefin copolymer at a proportion of 8 to 1% by mass, more preferably contains the lubricating base oil at a proportion of 95 to 99L by mass and the (C) ethylene- ⁇ -olefin copolymer at a proportion of 5 to 1Z by mass, and still more preferably contains the lubricating base oil at a proportion of 96 to 99% by mass and the (C) ethylene- ⁇ -olefin copolymer at a proportion of 4 to 1% by mass.
  • Examples of one preferred aspect include an aspect in which 30 to 100% by mass of the lubricating base oil is the (A) mineral oil.
  • a high proportion of (A) mineral oil occupied in the lubricating base oil provides excellent solubility of the additives described below, as well as facilitation of availability and excellent economic efficiency. 50 to 100% by mass of mineral oil is more preferred, and 80 to 100% by mass of mineral oil is still more preferred.
  • the Group III in the API categories is preferred because the Group III has excellent temperature viscosity characteristics and can achieve both oil film retention at a high temperature and a low torque at a low temperature.
  • Examples of another preferred aspect include an aspect in which 30 to 100% by mass of the lubricating base oil is the (B) synthetic oil, and the (B) synthetic oil is a poly- ⁇ -olefin and/or ester oil. 50 to 100t by mass of synthetic oil is more preferred, and 80 to 100% by mass of synthetic oil is still more preferred. A high proportion of the (B) synthetic oil occupied in the lubricating base oil is preferred since it renders heat resistance, temperature viscosity characteristics, and low temperature characteristics excellent.
  • the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle of the present invention may also contain additives such as an extreme pressure agent, a detergent dispersant, a viscosity index improver, an antioxidant, a corrosion inhibitor, an antiwear agent, a friction modifier, a pour point depressant, a rust inhibitor, and an antifoam agent.
  • additives such as an extreme pressure agent, a detergent dispersant, a viscosity index improver, an antioxidant, a corrosion inhibitor, an antiwear agent, a friction modifier, a pour point depressant, a rust inhibitor, and an antifoam agent.
  • additive used in the lubricating oil compositions of the present invention include the following additives, and one type of these additives can be used singly or in combinations of two or more thereof.
  • the extreme pressure agent is a general term for those having an anti-seizing effect when metals with each are exposed to a high load condition, and the agent is not particularly limited, and examples thereof include sulfur-based extreme pressure agents such as sulfides, sulfoxides, sulfones, thiophosphinates, thiocarbonates, sulfide oil and fat, and a sulfide olefin; phosphates such as a phosphate, a phosphite, a phosphate amine salt, and phosphite amines; halogene-based compounds such as a chlorinated hydrocarbon. These compounds may also be used in combinations of two or more types thereof.
  • a hydrocarbon or other organic components constituting the lubricating oil composition may be carbonized before the extreme pressure lubrication conditions due to heating and shearing, whereby a carbide coating may be formed on a metal surface. Therefore, a single use of the extreme pressure agent inhibits contact between the extreme pressure agent and a metal surface by the carbide coating, whereby the extreme pressure agent may not be expected to be fully effective.
  • a single extreme pressure agent may be added, however, since the lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle in the present invention is mainly composed of a saturated hydrocarbon such as the copolymer, it is preferable for the extreme pressure agent to be added in a state of being dissolved in advance in lubricating base oil such as mineral oil or synthetic hydrocarbon oil, together with other additive to be used, from the viewpoint of dispersibility. Specifically, more preferred is a method for selecting a so-called additive package in which various components such as an extreme pressure agent component are preliminarily compounded and further dissolved in lubricating base oil such as mineral oil or synthetic hydrocarbon oil, followed by adding the package to a lubricating oil composition.
  • DI packages are industrially supplied, in which various necessary additives for automatic transmission fluid and continuously variable transmission fluid are blended, and concentrated and dissolved in a lubricating oil such as mineral oil or synthetic hydrocarbon oil.
  • a lubricating oil such as mineral oil or synthetic hydrocarbon oil.
  • DI packages for automatic transmission fluid include HITEC 3419D manufactured by Afton Chemical Corporation and HITEC 2426 manufactured by Afton Chemical Corporation
  • DI packages for continuously variable transmission fluid include Lubrizol 6373 manufactured by Lubrizol Corporation.
  • the extreme pressure agent is used in a range of 0 to 10f by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • the antiwear agent include an inorganic or organic molybdenum compound such as molybdenum disulfide, graphite, antimony sulfide, and polytetrafluoroethylene.
  • the antiwear agent is used in a range of 0 to 3% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • friction modifier examples include amine compounds, imide compounds, fatty acid esters, fatty acid amides, and fatty acid metal salts, for example, which have at least one C6-C30 alkyl or alkenyl group in the molecule and particularly a linear C6-C30 alkyl or linear C6-C30 alkenyl group.
  • Examples of the amine compound include a linear or branched, preferably linear C6-C30 aliphatic monoamine, a linear or branched, preferably linear aliphatic polyamine, or an alkylene oxide adduct of these aliphatic amines, for example.
  • Examples of the imide compound include succinic imide having a linear or branched C6-C30 alkyl or alkenyl group and/or its modified compounds by carboxylic acid, boric acid, phosphoric acid, and sulfuric acid, for example.
  • Examples of the fatty acid ester include an ester of a linear or branched, preferably linear C7-C31 fatty acid and an aliphatic monovalent alcohol or an aliphatic polyhydric alcohol, for example.
  • fatty acid amide examples include an amide of a linear or branched, preferably linear C7-C31 fatty acid and an aliphatic monoamine or an aliphatic polyamine, for example.
  • fatty acid metal salt examples include alkaline earth metal salts (a magnesium salt and a calcium salt, for example) and zinc salts, for example, of linear or branched, preferably linear C7-C31 fatty acids.
  • the friction modifier is used in a range of 0.01 to 5.0Z by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • detergent dispersant examples include a metal sulfonate, a metal phenate, a metal phosphanate, and succinimide, for example.
  • the detergent dispersant is used in a range of 0 to 15% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • viscosity index improver in addition to an ethylene- ⁇ -olefin copolymer (excluding the (C) ethylene- ⁇ -olefin copolymer), known viscosity index improvers such as an olefin copolymer having a molecular weight exceeding 50,000, a methacrylate-based copolymer, a liquid polybutene, and a poly- ⁇ -olefin with 100C kinematic viscosity of 15 mm 2 /s or higher, can be combined for use.
  • the viscosity index improver is used in a range of 0 to 10% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • antioxidants examples include phenolic and amine-based compounds such as 2,6-di-t-butyl-4-methylphenol.
  • the antioxidant is used in a range of 0 to 3% by mass relative to 100Z by mass of the lubricating oil composition, if necessary.
  • the corrosion inhibitor examples include compounds such as benzotriazole, benzimidazole, and thiadiazole.
  • the corrosion inhibitor is used in a range of 0 to 3% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • rust inhibitor examples include compounds such as various amine compounds, carboxylic acid metal salts, polyhydric alcohol esters, phosphorus compounds, and sulfonates.
  • the rust inhibitor is used in a range of 0 to 3% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • the antifoaming agent examples include silicone-based compounds such as dimethylsiloxane and a silica gel dispersion, and an alcohol-based or ester-based compound.
  • the antifoaming agent is used in a range of 0 to 0.2% by mass relative to 100% by mass of the lubricating oil composition, if necessary.
  • pour point depressants can be used as the pour point depressant.
  • a polymer compound containing an organic acid ester group is used, and a vinyl polymer containing an organic acid ester group is particularly suitably used.
  • the vinyl polymer containing an organic acid ester group include (co)polymers of an alkyl methacrylate, (co)polymers of an alkyl acrylate, (co)polymers of an alkyl fumarate, (co)polymers of an alkyl maleate, and alkylated naphthalenes. It is preferably a (co)polymer of an alkyl acrylate, and more preferably a (co)polymer of an alkyl acrylate that is an ester compound of a C1-C10 alcohol and acrylic acid.
  • Such a pour point depressant has a melting point of ⁇ 13° C. or lower, preferably ⁇ 15° C., and still more preferably ⁇ 17° C. or lower.
  • the melting point of the pour point depressant is measured by using a differential scanning calorimeter (DSC). Specifically, the melting point is determined from the endothermic curve obtained when approximately 5 mg of a sample was filled in an aluminum pan, raised to a temperature of 200° C., held at 200° C. for 5 minutes, then cooled to ⁇ 40° C. at 10° C./min, held at ⁇ 40° C. for 5 minutes, and then heated at 10° C./min.
  • DSC differential scanning calorimeter
  • the aforementioned pour point depressant further has a weight-average molecular weight in terms of polystyrene, obtained by gel permeation chromatography, in a range of 20,000 to 400,000, preferably 30,000 to 300,000, and more preferably 40,000 to 200,000.
  • the pour point depressant is used in a range of 0 to 2% by mass, preferably 0.01 to 1% by mass, more preferably 0.02 to 0.4% by mass, and still more preferably 0.05 to 0.35% by mass, relative to 100% by mass of the lubricating oil composition, if necessary.
  • amount of the pour point depressant added exceeds the above range, shear stability of the lubricating oil composition may decrease, and lubricity may deteriorate due to lower viscosity. The pour point depressing ability may also be impaired.
  • an antiemulsifier a coloring agent, and an oily agent (oiliness agent), for example, can be used, if necessary.
  • DI packages may also be used, in which various necessary additives used in automatic transmission fluid and continuously variable transmission fluid are blended, and concentrated and dissolved in a lubricating oil such as mineral oil or synthetic hydrocarbon oil.
  • DI packages are industrially supplied, and examples of DI packages for automatic transmission fluid include HITEC 3419D manufactured by Afton Chemical Corporation and HITEC 2426 manufactured by Afton Chemical Corporation, and examples of DI packages for continuously variable transmission fluid include Lubrizol 6373 manufactured by Lubrizol Corporation. These DI packages can also be applied to the lubricating oil composition of the present invention.
  • the lubricating oil composition of the present invention can be used, for example, for cooling of an electric motor and lubrication of a gear installed in an electric vehicle such as an electric automobile, a plug-in hybrid vehicle, a hybrid vehicle, or a fuel cell vehicle, and has extremely superior temperature viscosity characteristics compared to conventional lubricating oils containing the same lubricating base oil, that is, oil film retention at a high temperature and low temperature viscosity characteristics, and can greatly contribute to energy saving in electric vehicles.
  • electric vehicles it is particularly useful in electric vehicles equipped with in-wheel motors, where the distance between the gear and the electric motor is short, that is, high heat dissipation is required.
  • the lubricating oil composition of the present invention is extremely excellent in heat dissipation performance, and thus has high electric motor cooling performance as well as lubricating performance for a gear and a bearing in an electric vehicle.
  • the lubricating oil composition of the present invention is extremely useful in cooling of an electric motor and lubrication of a gear in an electric vehicle.
  • Ethylene ⁇ molar ⁇ content ⁇ rate ⁇ ( mol ⁇ % ) [ Ethylene ⁇ weight ⁇ content ⁇ rate ⁇ ( wt ⁇ % ) + 28 ] [ Ethylene ⁇ weight ⁇ content ⁇ rate ⁇ ( wt ⁇ % ) + 28 ] + [ Propylene ⁇ weight ⁇ content ⁇ rate ⁇ ( wt ⁇ % ) + 42 ]
  • the 100° C. kinematic viscosity, the 40° C. kinematic viscosity, and the viscosity index were measured by the method described in JIS K2283.
  • the molecular weight distribution was measured by using a HLC-8320 GPC manufactured by Tosoh Corporation as follows. TSKgel SuperMultipore HZ-M columns (4 columns) were used as separation columns, a column temperature was 40° C., tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a mobile phase, an expansion rate was set at 0.35 ml/min, a sample concentration was 5.5 g/L, sample injection volume was 20 ⁇ l, and a differential refractometer was used as a detector. Standard polystyrenes manufactured by Tosoh Corporation (PStQuick MP-M) were used.
  • PStQuick MP-M Standard polystyrenes manufactured by Tosoh Corporation
  • the weight-average molecular weight (Mw) and the 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.
  • the APHA value was determined according to the method described in JIS K0071.
  • P E represents a molar fraction of ethylene component
  • Pc represents a molar fraction of ⁇ -olefin component
  • Pot represents a molar fraction of ethylene- ⁇ -olefin sequence in the total dyad sequence.
  • the thermal diffusivity is represented by the following formula by determining each of the thermal conductivity, specific heat, and density of the lubricating oil composition.
  • Thermal ⁇ diffusivity ⁇ ( m 2 / s ) [ Thermal ⁇ conductivity ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ] [ Specific ⁇ heat ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ] ⁇ [ Density ⁇ of ⁇ lubricating ⁇ oil ⁇ composition ]
  • the thermal conductivity was measured at a test temperature of 50° C. in accordance with JIS R2616.
  • the specific heat was measured continuously under adiabatic conditions between 30° C. and 80C in an air atmosphere using a specific heat measuring apparatus SH-3000 model manufactured by SHINKU-RIKO Inc., and the specific heat at 50C was employed.
  • the density was measured at 50° C. in accordance with JIS K2249.
  • the volume resistivity was measured at a test temperature of 50C and at 250 V in accordance with JIS C2101.
  • the relative permittivity was measured at a test temperature of 50° C. in accordance with JIS C2138.
  • melting point (Tm) a temperature at which the enthalpy curve obtained during a temperature raising process exhibits the maximum value was determined as a melting point (Tm), and the total endothermic value accompanying melting was defined as heat of fusion ( ⁇ H). No peak observed or a value of heat of fusion ( ⁇ H) of 1 J/g or less was deemed to indicate no melting point (Tm).
  • Tm melting point
  • ⁇ H heat of fusion
  • ICS-1600 an ethylene- ⁇ -olefin copolymer was placed in a sample boat, and underwent fire decomposition at a combustion furnace at a set temperature of 900C in an Ar/O 2 gas stream. The generated gas obtained was absorbed into an absorbent solution, and the chlorine content was determined by ion chromatography.
  • the pour point was measured according to the method described in ASTM D97. Note that when the pour point was below ⁇ 50° C., it was described as ⁇ 50.
  • the low temperature viscosity at ⁇ 40° C. was measured by the method described in ASTM D6821.
  • the lubricating oil composition was subjected to ultrasonic irradiation for 60 minutes in accordance with JASO M347, a test method for automatic transmission fluid shear stability, and the rate of decrease in kinematic viscosity at 100C due to irradiation (rate of decrease in viscosity after shear test) represented by the following formula was evaluated.
  • Rate ⁇ of ⁇ decrease ⁇ in ⁇ viscosity after ⁇ shear ⁇ test ⁇ ( % ) [ 100 ⁇ ° ⁇ C . kinematic ⁇ viscosity ⁇ before ⁇ ultrasonic ⁇ irradiation ] - [ 100 ⁇ ° ⁇ C . kinematic ⁇ viscosity ⁇ after ⁇ ultrasonic ⁇ irradiation ] [ 100 ⁇ ° ⁇ C . kinematic ⁇ viscosity ⁇ before ⁇ ultrasonic ⁇ irradiation ] ⁇ 100
  • Ethylene- ⁇ -olefin copolymers (B) were produced according to the following Polymerization Examples. Note, however, the obtained ethylene- ⁇ -olefin copolymer (B) underwent hydrogenation operation, if necessary, by the following method.
  • a stainless steel autoclave with an internal volume of 1 L was added with 100 mL of a hexane solution of a 0.5% by mass Pd/alumina catalyst and 500 mL of a 30% by mass hexane solution of the ethylene- ⁇ -olefin copolymer, and was sealed followed by nitrogen substitution.
  • the mixture was then raised to a temperature of 140° C. under stirring, and then the inner system was substituted with hydrogen and was increased to a pressure of 1.5 MPa with hydrogen to carry out a hydrogenation reaction for 15 minutes.
  • a 100 mL Schlenk tube was sequentially added with 1.50 g (3.36 mmol) of methyl (cyclopentadienyl) (2,7-di-t-butylfluorenyl) (phenyl)methane, 50 mL of dehydrated toluene and 570 ⁇ L (7.03 mmol) of THF. While cooling it in an ice bath, a n-butyl lithium/hexane solution (1.65 M) 4.20 mL (6.93 mmol) was added gradually, and stirred at 45° C. for 5 hours. The solvent was removed under reduced pressure and 40 mL of dehydrated diethyl ether was added to prepare a red solution.
  • the polymerization was completed by having added a small amount of ethanol to the system, and then the unreacted ethylene, propylene, and hydrogen were purged.
  • the resulting polymer solution was washed with 1000 mL of 0.2 mol/l hydrochloric acid three times and then with 1000 mL of distilled water three times, dried over magnesium sulfate, and the solvent was removed under reduced pressure.
  • the resulting polymer was dried overnight under reduced pressure at 80° C., to obtain 22.2 g of an ethylene-propylene copolymer. Furthermore, the ethylene-propylene copolymer was subjected to the hydrogenation operation, and thus a polymer 1 was obtained.
  • the polymerization was completed by having added a small amount of ethanol to the system, and then the unreacted ethylene, propylene, and hydrogen were purged.
  • the resulting polymer solution was washed with 1000 mL of 0.2 mol/l hydrochloric acid three times and then with 1000 mL of distilled water three times, dried over magnesium sulfate, and the solvent was removed under reduced pressure.
  • the resulting polymer was dried overnight under reduced pressure at 80° C., to obtain 34.2 g of an ethylene-propylene copolymer. Furthermore, the ethylene-propylene copolymer was subjected to the hydrogenation operation, and thus a polymer 2 was obtained.
  • the polymerization was completed by having added a small amount of ethanol to the system, and then the unreacted ethylene, propylene, and hydrogen were purged.
  • the resulting polymer solution was washed with 1000 mL of 0.2 mol/l hydrochloric acid three times and then with 1000 mL of distilled water three times, dried over magnesium sulfate, and the solvent was removed under reduced pressure.
  • the resulting polymer was dried overnight under reduced pressure at 80° C., to obtain 52.2 g of an ethylene-propylene copolymer. Furthermore, the ethylene-propylene copolymer was subjected to the hydrogenation operation, and thus a polymer 3 was obtained.
  • a fully nitrogen-substituted glass polymerizer with an internal volume of 1 L was charged with 250 mL of heptane, a temperature in the system was raised to 50° C., and then ethylene, propylene, and hydrogen at a flow rate of 25 L/hr, 75 L/hr, and 100 L/hr, respectively, were continuously fed into the polymerizer, and the mixture was stirred at a stirring speed of 600 rpm.
  • PAO Poly- ⁇ -olefin
  • a lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle was compounded and prepared so that viscosity thereof was equivalent to ISO 46 and the total amount of the (A) mineral oil and the polymer 1 as the (C) ethylene- ⁇ -olefin copolymer, together with the DI package and pour point depressant, was 100Z by mass.
  • the amounts of each component added and the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the polymer 2 and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the polymer 3 and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the polymer 4 and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the polymethacrylate (PHA), no pour point depressant was added, and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the poly- ⁇ -olefin (PAO) and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • a lubricating oil composition was compounded and prepared in the same manner as in Example 1, except that the polymer 1 was replaced with the polybutene (PIB) and the amount of each component added was adjusted as described in Table 3.
  • the physical properties of the lubricating oil composition are shown in Table 3.
  • Example Example Comparative Comparative Comparative 1 2 3 4 Example 1 Example 2 Example 3 Polymer 1 % by mass 5.0 Polymer 2 % by mass 3.5 Polymer 3 % by mass 1.9 Polymer 4 % by mass 1.4 PMA % by mass 2.6 PAO % by mass 3.0 PIB % by mass 4.8 Pour point depressant % by mass 0.3 0.3 0.3 0.3 0.3 DI package % by mass 12.0 12.0 12.0 12.0 12.0 12.0 12.0 Mineral oil % by mass 82.7 84.2 85.8 86.3 85.4 84.7 82.9 100° C. kinematic mm 2 /s 4.38 4.36 4.35 4.39 4.32 4.36 4.38 viscosity 40° C.
  • the lubricating oil compositions of Comparative Examples 2 and Comparative Example 3, which contain PAO or PIB instead of the (C) ethylene- ⁇ -olefin copolymer have a thermal diffusivity below 7.0 ⁇ 10 ⁇ 2 , which does not provide sufficient motor cooling performance.
  • the (C) ethylene- ⁇ -olefin copolymer has a methylene sequence as the main backbone, and the degree of freedom at the molecular ends is smaller than that of PAO and PIB, which inhibits heat generation due to molecular vibration. Therefore, when used in lubricating oil compositions, it is thought to exhibit excellent cooling and/or heat dissipation performance. In addition, they have poor pourability at a low temperature, resulting in significantly inferior fuel saving properties in a low temperature environment.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Lubricants (AREA)
US18/842,784 2022-03-03 2023-03-03 Lubricating oil composition Pending US20250171704A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2022-032865 2022-03-03
JP2022032865 2022-03-03
PCT/JP2023/007952 WO2023167307A1 (ja) 2022-03-03 2023-03-03 潤滑油組成物

Publications (1)

Publication Number Publication Date
US20250171704A1 true US20250171704A1 (en) 2025-05-29

Family

ID=87883835

Family Applications (1)

Application Number Title Priority Date Filing Date
US18/842,784 Pending US20250171704A1 (en) 2022-03-03 2023-03-03 Lubricating oil composition

Country Status (6)

Country Link
US (1) US20250171704A1 (https=)
EP (1) EP4488348A4 (https=)
JP (1) JPWO2023167307A1 (https=)
KR (1) KR20240137667A (https=)
CN (1) CN118742629A (https=)
WO (1) WO2023167307A1 (https=)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025197525A1 (ja) * 2024-03-22 2025-09-25 三井化学株式会社 潤滑油組成物

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6459005B1 (en) * 1999-04-09 2002-10-01 Mutsui Chemicals, Inc. Ethylene/α-olefin copolymer, method for producing the same, and use thereof
JP2016069404A (ja) * 2014-09-26 2016-05-09 三井化学株式会社 潤滑油組成物
US11155768B2 (en) * 2017-01-16 2021-10-26 Mitsui Chemicals, Inc. Lubricant oil compositions for automotive gears

Family Cites Families (50)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3382291A (en) 1965-04-23 1968-05-07 Mobil Oil Corp Polymerization of olefins with bf3
US3780128A (en) 1971-11-03 1973-12-18 Ethyl Corp Synthetic lubricants by oligomerization and hydrogenation
US3763244A (en) 1971-11-03 1973-10-02 Ethyl Corp Process for producing a c6-c16 normal alpha-olefin oligomer having a pour point below about- f.
US3909432A (en) 1973-11-26 1975-09-30 Continental Oil Co Preparation of synthetic hydrocarbon lubricants
US4032591A (en) 1975-11-24 1977-06-28 Gulf Research & Development Company Preparation of alpha-olefin oligomer synthetic lubricant
JPS5771532U (https=) 1980-10-16 1982-05-01
JPS5779376U (https=) 1980-11-04 1982-05-17
JPH0224701A (ja) 1988-07-13 1990-01-26 Sekisui Chem Co Ltd 電気機器の駆動制御装置
JP2741893B2 (ja) 1988-09-14 1998-04-22 三井化学株式会社 ベンゼン不溶性の有機アルミニウムオキシ化合物の製造方法
JP2693517B2 (ja) 1988-09-14 1997-12-24 三井石油化学工業株式会社 ベンゼン不溶性の有機アルミニウムオキシ化合物の製造方法
US5041584A (en) 1988-12-02 1991-08-20 Texas Alkyls, Inc. Modified methylaluminoxane
US4960878A (en) 1988-12-02 1990-10-02 Texas Alkyls, Inc. Synthesis of methylaluminoxanes
US4926004A (en) 1988-12-09 1990-05-15 Mobil Oil Corporation Regeneration of reduced supported chromium oxide catalyst for alpha-olefin oligomerization
US4967032A (en) 1989-09-05 1990-10-30 Mobil Oil Corporation Process for improving thermal stability of synthetic lubes
JPH03103407A (ja) 1989-09-18 1991-04-30 Idemitsu Kosan Co Ltd オレフィン系重合体の製造法
JP2796376B2 (ja) 1989-10-18 1998-09-10 出光興産株式会社 合成潤滑油の製造法
JP2545006B2 (ja) 1990-07-03 1996-10-16 ザ ダウ ケミカル カンパニー 付加重合触媒
JP2593264B2 (ja) 1990-12-14 1997-03-26 三井石油化学工業株式会社 イミド基含有低分子量エチレン共重合体、その製造方法およびその利用
US5171908A (en) 1991-11-18 1992-12-15 Mobil Oil Corporation Synthetic polyolefin lubricant oil
EP0668342B1 (en) 1994-02-08 1999-08-04 Shell Internationale Researchmaatschappij B.V. Lubricating base oil preparation process
EP1365005B1 (en) 1995-11-28 2005-10-19 Shell Internationale Researchmaatschappij B.V. Process for producing lubricating base oils
CA2237068C (en) 1995-12-08 2005-07-26 Exxon Research And Engineering Company Biodegradable high performance hydrocarbon base oils
US6090989A (en) 1997-10-20 2000-07-18 Mobil Oil Corporation Isoparaffinic lube basestock compositions
US6059955A (en) 1998-02-13 2000-05-09 Exxon Research And Engineering Co. Low viscosity lube basestock
US6008164A (en) 1998-08-04 1999-12-28 Exxon Research And Engineering Company Lubricant base oil having improved oxidative stability
US6165949A (en) 1998-09-04 2000-12-26 Exxon Research And Engineering Company Premium wear resistant lubricant
US6080301A (en) 1998-09-04 2000-06-27 Exxonmobil Research And Engineering Company Premium synthetic lubricant base stock having at least 95% non-cyclic isoparaffins
US6103099A (en) 1998-09-04 2000-08-15 Exxon Research And Engineering Company Production of synthetic lubricant and lubricant base stock without dewaxing
US6475960B1 (en) 1998-09-04 2002-11-05 Exxonmobil Research And Engineering Co. Premium synthetic lubricants
US6332974B1 (en) 1998-09-11 2001-12-25 Exxon Research And Engineering Co. Wide-cut synthetic isoparaffinic lubricating oils
FR2798136B1 (fr) 1999-09-08 2001-11-16 Total Raffinage Distribution Nouvelle huile de base hydrocarbonee pour lubrifiants a indice de viscosite tres eleve
US7067049B1 (en) 2000-02-04 2006-06-27 Exxonmobil Oil Corporation Formulated lubricant oils containing high-performance base oils derived from highly paraffinic hydrocarbons
JP2004051676A (ja) 2002-07-16 2004-02-19 Mitsui Chemicals Inc エチレン系共重合体の製造方法
JP4367687B2 (ja) 2002-11-26 2009-11-18 三井化学株式会社 オレフィン重合用の架橋メタロセン化合物およびそれを用いたオレフィンの重合方法
JP2005200447A (ja) 2004-01-13 2005-07-28 Mitsui Chemicals Inc 潤滑油添加剤および潤滑油組成物
JP2005200448A (ja) 2004-01-13 2005-07-28 Mitsui Chemicals Inc 潤滑油添加剤および潤滑油組成物
JP5070049B2 (ja) 2004-07-30 2012-11-07 ザ ルブリゾル コーポレイション 芳香族アミンを含有する分散剤粘度調整剤
JP2006325369A (ja) * 2005-05-20 2006-11-30 Nissan Motor Co Ltd 電動モータの冷却装置
US8748361B2 (en) 2005-07-19 2014-06-10 Exxonmobil Chemical Patents Inc. Polyalpha-olefin compositions and processes to produce the same
JP4142060B2 (ja) 2006-04-17 2008-08-27 新日本石油株式会社 自動変速機用潤滑油組成物
JP2012031359A (ja) * 2009-12-28 2012-02-16 Idemitsu Kosan Co Ltd 機器冷却用基油、該基油を配合してなる機器冷却油、該冷却油により冷却される機器、および該冷却油による機器冷却方法
WO2011080970A1 (ja) 2009-12-29 2011-07-07 出光興産株式会社 潤滑油組成物
JP5779376B2 (ja) 2011-03-29 2015-09-16 Ｊｘ日鉱日石エネルギー株式会社 潤滑油組成物
JP2012244810A (ja) 2011-05-20 2012-12-10 Alphana Technology Co Ltd インホイールモータ
JP5906710B2 (ja) * 2011-12-14 2016-04-20 日産自動車株式会社 回転電機
JP6320262B2 (ja) * 2014-09-26 2018-05-09 三井化学株式会社 潤滑油組成物
JP6228104B2 (ja) * 2014-12-04 2017-11-08 東燃ゼネラル石油株式会社 潤滑油組成物
FR3072685B1 (fr) * 2017-10-20 2020-11-06 Total Marketing Services Composition pour refroidir et lubrifier un systeme de motorisation d'un vehicule
JP2019154115A (ja) * 2018-03-01 2019-09-12 本田技研工業株式会社 回転電機の冷却システムおよびこれを備えた回転電機
JP7392551B2 (ja) * 2020-03-31 2023-12-06 ニデック株式会社 駆動装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6459005B1 (en) * 1999-04-09 2002-10-01 Mutsui Chemicals, Inc. Ethylene/α-olefin copolymer, method for producing the same, and use thereof
JP2016069404A (ja) * 2014-09-26 2016-05-09 三井化学株式会社 潤滑油組成物
US11155768B2 (en) * 2017-01-16 2021-10-26 Mitsui Chemicals, Inc. Lubricant oil compositions for automotive gears

Also Published As

Publication number Publication date
KR20240137667A (ko) 2024-09-20
WO2023167307A1 (ja) 2023-09-07
EP4488348A4 (en) 2026-03-11
EP4488348A1 (en) 2025-01-08
CN118742629A (zh) 2024-10-01
JPWO2023167307A1 (https=) 2023-09-07

Similar Documents

Publication Publication Date Title
JP6618891B2 (ja) エチレン／α−オレフィン共重合体および潤滑油
JP6741790B2 (ja) 自動車ギア用潤滑油組成物
JP6320262B2 (ja) 潤滑油組成物
JP6392055B2 (ja) 潤滑油組成物
JP6326337B2 (ja) 工業ギア用潤滑油組成物
JP6326340B2 (ja) グリース組成物
JP6326339B2 (ja) 作動油用潤滑油組成物
JP6490086B2 (ja) 潤滑油組成物
JP6326354B2 (ja) 潤滑油組成物
US20250171704A1 (en) Lubricating oil composition
JP6326338B2 (ja) 圧縮機油用潤滑油組成物
US12398338B2 (en) Viscosity modifier for lubricating oil and lubricating oil composition for hydraulic fluid
JP6773567B2 (ja) 自動車ギア用潤滑油組成物
JP7785531B2 (ja) 自動車変速機用潤滑油組成物
JP6773566B2 (ja) 自動車ギア用潤滑油組成物
JP6840544B2 (ja) 自動車変速機用潤滑油組成物

Legal Events

Date Code Title Description
AS Assignment

Owner name: MITSUI CHEMICALS, INC., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KANAYA, HIROTAKA;ABE, SHOTA;REEL/FRAME:068447/0094

Effective date: 20240820

STPP Information on status: patent application and granting procedure in general

Free format text: NON FINAL ACTION MAILED

STPP Information on status: patent application and granting procedure in general

Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER

STPP Information on status: patent application and granting procedure in general

Free format text: FINAL REJECTION COUNTED, NOT YET MAILED

STPP Information on status: patent application and granting procedure in general

Free format text: FINAL REJECTION MAILED

STPP Information on status: patent application and granting procedure in general

Free format text: FINAL REJECTION MAILED

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION