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
  • 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
  • C10M137/00—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing phosphorus
• • 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
  • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
  • C10M171/02—Specified values of viscosity or viscosity index
• • 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
• • 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
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant compositions
  • C10M2215/086—Imides
• • 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
  • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant compositions
  • C10M2215/28—Amides; Imides
• • 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
  • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
  • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
  • C10M2223/04—Phosphate esters
  • C10M2223/045—Metal containing thio derivatives
• • 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
  • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
  • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
  • C10M2223/049—Phosphite
• • 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
  • 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
  • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
• • 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
  • C10N2030/10—Inhibition of oxidation, e.g. anti-oxidants
• • 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
  • C10N2040/042—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives for automatic transmissions

Definitions

• the present invention relates to a lubricant composition for automatic transmissions, in particular, to a lubricant composition for automatic transmissions, particularly for vehicles, which prolongs fatigue life of gears irrespective of its low viscosity, and which is excellent and well-balanced in sustainability of anti-shudder property, low-temperature viscosity characteristics, oxidation stability, and durability of friction characteristics.
• One means for making automatic transmissions energy-conserving is to lower the viscosity of a lubricant used therein.
• a vehicle automatic transmission for example, which has a torque converter, a wet clutch, gear-bearing mechanisms, an oil pump, and a hydraulic control mechanism, the agitation resistance and friction resistance in these parts are reduced, which results in improvement in power transmission efficiency and thus in vehicle fuel efficiency.
• the lowered viscosity of lubricants used in these parts may remarkably shorten their fatigue life, causing seizure or the like to result in troubles in the transmission.
• a phosphorus extreme pressure agent is used for improving extreme pressure property of a low-viscosity lubricant, fatigue life of gears is remarkably impaired, so that it is usually hard to lower the viscosityof such lubricant.
• a sulfur extreme pressure agent may improve fatigue life of gears, but impairs oxidation stability, so that a large amount of antioxidants is required.
• compositions are not intended to improve fuel efficiency, and thus have a high kinematic viscosity.
• There are recently proposed automatic transmission fluids having a lowered viscosity for example, in JP-2004-169025-A , JP-2004-155924-A , and JP-2004-155873-A .
• These lubricants have excellent sustainability of anti-shudder property, low-temperature viscosity characteristics, and oxidation stability, but are yet to be improved in excellence and balance of durability of friction characteristics, contribution to energy conservation, and anti-fatigue performance on gears.
• the present inventors have made intensive studies for solving the above problems to find out that a low-viscosity lubricant composition for automatic transmissions wherein particular base oils and particular additives are combined, may solve the above problems, thereby completing the present invention.
• a lubricant composition for automatic transmissions comprising:
• the present composition is capable of prolonging fatigue life of gears irrespective of its low viscosity, has excellent sustainability of anti-shudder property, low-temperature viscosity characteristics, and oxidation stability, and is excellent and well-balanced in durability of friction characteristics, energy-conserving performance, and anti-fatigue performance on gears.
• the present composition is particularly suitable for vehicle automatic transmissions, has both energy-conserving performance and anti-fatigue performance on gears, and is capable of achieving energy conservation of vehicles.
• the present composition is characterized in that the particular lubricant base oil (A) and particular components (B) to (E) are contained at a good balance, and the kinematic viscosity at 100 °C is in the range of 5.6 to 5.8 mm 2 /s.
• the present composition is capable of prolonging fatigue life of gears irrespective of its low viscosity, and is excellent and well-balanced in sustainability of anti-shudder property, low-temperature viscosity characteristics, oxidation stability, and durability of friction characteristics.
• the kinematic viscosity at 100 °C of the present composition is higher than 5.8 mm 2 /s, the energy-conserving performance given by reduction of agitation resistance and excellent low-temperature viscosity characteristics cannot be achieved sufficiently. If the kinematic viscosity is lower than 5.6 mm 2 /s, fatigue life of gears cannot be prolonged sufficiently.
• the lubricant base oil (A) includes lubricant base oil (A1) having a kinematic viscosity at 100 °C of 2.5 to 4.5 mm 2 /s (sometimes referred to as component (A1) hereinbelow), i.e. one or more lubricant base oils (A1) selected from the group consisting of mineral and synthetic base oils having the particular kinematic viscosity, and lubricant base oil (A2) having a kinematic viscosity at 100 °C of 10 to 40 mm 2 /s (sometimes referred to as component (A2) hereinbelow).
• the mineral base oil may be, for example, paraffin or naphthene mineral base oils refined by atmospheric-distilling crude oil followed by vacuum-distillation of the atmospheric residue, and refining the resulting lubricant fraction by one or a suitable combination of solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, washing with sulfuric acid, and clay treatment; or normal paraffin or isoparaffin.
• solvent deasphalting solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, washing with sulfuric acid, and clay treatment
• normal paraffin or isoparaffin one or a combination of two or more of these base oils at any ratio may be used.
• Examples of preferred mineral base oils may be as follows:
• the ordinary refining processes as used herein are not particularly limited, and any refining processes used in production of lubricant base oils may be employed.
• Examples of the ordinary refining processes may include (a) hydrorefining, such as hydrocracking or hydrofinishing; (b) solvent refining, such as furfural solvent extraction; (c) dewaxing, such as solvent dewaxing or contact dewaxing; (d) clay refining using acid clay or activated clay; and (e) chemical (acid or alkali) refining, such as washing with sulfuric acid or caustic soda.
• hydrorefining such as hydrocracking or hydrofinishing
• solvent refining such as furfural solvent extraction
• dewaxing such as solvent dewaxing or contact dewaxing
• clay refining using acid clay or activated clay such as washing with sulfuric acid or caustic soda.
• chemical (acid or alkali) refining such as washing with sulfuric acid or caustic
• Particularly preferred mineral base oils may be those obtained by subjecting a base oil selected from above (1) to (8) to the following treatment.
• hydrocracked mineral oils and/or wax-isomerized isoparaffin base oils may preferably be used, which are obtained by subjecting the lubricant fraction of a base oil selected from above (1) to (8) to hydrocracking or wax-isomerization, then subjecting the resulting product or the lubricant fraction thereof to dewaxing, such as solvent or contact dewaxing, followed by solvent refining, or to solvent ref ining followed by dewaxing, such as solvent or contact dewaxing.
• the hydrocracked mineral oil and/or wax-isomerized isoparaffin base oil is preferably used in an amount of not less than 30 mass%, more preferably not less than 50 mass%, most preferably not less than 70 mass% of the total amount of the mineral base oil.
• the synthetic base oil may be, for example, poly- ⁇ -olefin or hydrides thereof, isobutene oligomer or hydrides thereof, isoparaffin, alkylbenzene, alkylnaphthalene; diesters, such as ditridecyl glutarate, di-2-ethylhexyl adipate, isodecyl adipate, ditridecyl adipate, or di-2-ethylhexyl sebacate; polyol esters, such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, or pentaerythritol pelargonate; polyoxyalkylene glycols, dialkyldiphenyl ethers, or polyphenyl ethers.
• poly- ⁇ -olefin or hydrides thereof may preferably be used.
• Poly- ⁇ -olefin may be an oligomer or a co-oligomer of ⁇ -olefin having usually 2 to 32, preferably 6 to 16 carbon atoms. More specifically, 1-octene oligomer, 1-decene oligomer, ethylene-propylene co-oligomer, or hydrides thereof, may be used.
• the poly- ⁇ -olefin may be prepared by any process without specific limitation, for example, by polymerizing ⁇ -olefin in the presence of a polymerization catalyst, such as a Friedel-Crafts catalyst, including aluminum trichloride, boron trifluoride, or a complex of boron trifluoride with water, alcohol, such as ethanol, propanol, or butanol, carboxylic acid, or an ester, such as ethyl acetate or ethyl propionate.
• a polymerization catalyst such as a Friedel-Crafts catalyst, including aluminum trichloride, boron trifluoride, or a complex of boron trifluoride with water, alcohol, such as ethanol, propanol, or butanol, carboxylic acid, or an ester, such as ethyl acetate or ethyl propionate.
• component (A1) contains at least one mineral or synthetic base oil.
• at least one mineral or synthetic base oil For example, two or more mineral base oils, two or more synthetic base oils, a mixture thereof, or a mixture of at least one mineral base oil and at least one synthetic base oil may be used.
• component (A1) is a mixture, the mixing ratio of the base oils therein may be selected arbitrarily, as long as the kinematic viscosity at 100 °C of each base oil is 2.5 to 4.5 mm 2 /s.
• Component (A1) may preferably be one or more base oils selected from the following base oils (A1a) to (A1c):
• the %C A of component (A1) is not particularly limited, and may preferably be not higher than 3, more preferably not higher than 2, and particularly preferably not higher than 1. With the %C A of component (A1), or even lubricant base oil (A), of not higher than 3, a composition having still more excellent oxidation stability may be obtained.
• %C A refers to a percent of the number of aromatic carbons with respect to the total carbon number determined in accordance with ASTM D 3238-85.
• the viscosity index of component (A1) is not particularly limited, and may preferably be not lower than 80, more preferably not lower tan 90, particularly preferably not lower than 110, and usually not higher than 200, more preferably not higher than 160.
• the viscosity index of not lower than 80 a composition exhibiting excellent viscosity characteristics from lower temperatures to higher temperatures may be obtained, but with too high a viscosity index, the effect of the composition on fatigue life of gears may be lowered.
• the sulfur content of component (A1) is not particularly limited, and may preferably be not higher than 0.05 mass%, more preferably not higher than 0.02 mass%, particularly preferably not higher than 0.005 mass% of the total amount of component (A1). With a reduced sulfur content of component (A1), a composition having still more excellent oxidation stability may be obtained.
• Each of base oils (A1a) to (A1c) may be used alone or mixed in any combination or ratio. It is particularly preferred to use a combination of base oil (A1a) and base oil (A1b) and/or (A1c).
• the content of base oil (A1c) is preferably 1 to 50 mass%, more preferably 3 to 20 mass%, particularly preferably 5 to 15 mass% of the total amount of lubricant base oil (A). With the content of base oil (A1c) being about 5 to 15 mass%, a composition having excellent anti-fatigue performance, low-temperature characteristics, and oxidation stability may be obtained effectively at low cost.
• component (A2) acts for further improving fatigue life of gears, and may be one or more base oils selected from the following base oils (A2a) to (A2c) :
• the %C A of component (A2) is usually 0 to 40 but not particularly limited, and may preferably be not lower than 2, more preferably not lower than 4, particularly preferably not lower than 6, and preferably not higher than 15, more preferably not higher than 10, particularly preferably not higher than 8, for balancing good oxidation stability and anti-fatigue performance.
• the viscosity index of component (A2) is not particularly limited, and may preferably be not lower than 80, more preferably not lower than 90, particularly preferably not lower than 95, and usually not higher than 200, preferably not higher than 120, more preferably not higher than 110, particularly preferably not higher than 100.
• the viscosity index of not lower than 80 a composition exhibiting excellent viscosity characteristics from lower temperatures to higher temperatures may be obtained, but with too high a viscosity index, the effect of the composition on fatigue life of gears may be lowered.
• the sulfur content of component (A2) is not particularly limited, and may usually be 0 to 2 mass%, preferably 0.05 to 1.5 mass%, more preferably 0.3 to 1.2 mass%, still more preferably 0.5 to 1 mass%, particularly preferably 0.7 to 1. 0 mass% of the total amount of component (A2).
• component (A2) having a relatively high sulfur content, anti-fatigue performance may be improved, whereas with component (A2) preferably having a sulfur content of not higher than 1.0 mass%, a composition having still more excellent oxidation stability may be obtained.
• component (A2) it is preferred to use, as component (A2), base oil (A2b) or (A2c) for improving anti-fatigue performance, and base oil (A2b) for balancing the oxidation stability and anti-fatigue performance.
• base oil (A1c) used as component (A1) a composition having excellent oxidation stability and low-temperature viscosity characteristics and anti-fatigue performance, may be obtained.
• the contents of components (A1) and (A2) are not particularly limited, and the content of component (A1) may preferably be 70 to 97 mass%, more preferably 85 to 95 mass%, and the content of component (A2) may preferably be 3 to 30 mass%, more preferably 5 to 15 mass%, of the total amount of lubricant base oil (A) .
• Lubricant base oil (A) which is composed of components (A1) and (A2), has a kinematic viscosity at 100 °C of 3.7 to 4.1 mm 2 /s, preferably 3.9 to 4.1 mm 2 /s .
• a kinematic viscosity at 100 °C of not higher than 4.1 mm 2 /s fluid resistance is lowered, so that a lubricant composition exhibiting still lower friction resistance at lubricating sites may be obtained.
• a composition having excellent low-temperature viscosity for example, a Brookfield viscosity at -40 °C of not higher than 15000 mPa ⁇ s, may be obtained.
• a composition may be obtained which is capable of forming a sufficient oil film, has still more excellent lubricity and anti-fatigue performance, and exhibits still lower base oil evaporation loss under high-temperature conditions.
• the %C A of lubricant base oil (A) is not particularly limited, and may preferably be not higher than 3, more preferably not higher than 2, particularly preferably not higher than 1, and preferably not lower than 0.1, more preferably not lower than 0.5. With the %C A of lubricant base oil (A) of not higher than 3, a composition having still more excellent oxidation stability may be obtained.
• the viscosity index of lubricant base oil (A) is not particularly limited, and may preferably be not lower than 80, more preferably not lower than 90, particularly preferably not lower than 110. With the viscosity index of not lower than 80, a composition exhibiting excellent viscosity characteristics from lower temperatures to higher temperatures may be obtained.
• the sulfur content of lubricant base oil (A) is not particularly limited, and may preferably be 0 to 0.3 mass%, more preferably 0.03 to 0.2 mass%, particularly preferably 0.06 to 0.1 mass%. With the sulfur content of lubricant base oil (A) in the above range, in particular 0.03 to 0.2 mass%, anti-fatigue performance and oxidation stability may be balanced.
• component (B) is a poly(meth)acrylate viscosity index improver having a weight average molecular weight of 15000 to 30000, which is obtained by diluting a poly (meth) acrylate compound with a diluent.
• the weight average molecular weight of the poly(meth)acrylate compound may preferably be 17000 to 25000, more preferably 18000 to 24000, for further improvement in anti-fatigue performance.
• the weight average molecular weight means a weight average molecular weight measured with 150-C ALC/GPC system manufactured by WATERS CORPORATION equipped with two GMHHR-M (7.8 mmID x 30 cm) columns manufactured by TOSOH CORPORATION arranged in series, using tetrahydrofuran as a solvent, at 23 °C, at a flow rate of 1 mL/min, a sample concentration of 1 mass%, sample injection volume of 75 ⁇ L, and determined with a differential refractive index detector (RI) against a calibration curve obtained from polystyrene standard.
• RI differential refractive index detector
• the poly(meth)acrylate in the poly(meth)acrylate compound constituting component (B) maypreferably be those having a structural unit represented by the formula (1):
• R 1 stands for a hydrogen atom or a methyl group, preferably a methyl group
• R 2 stands for a hydrocarbon group having 1 to 30 carbon atoms or a group represented by the formula - (R) a-E, wherein R stands for an alkylene group having 1 to 30 carbon atoms, E stands for an amine or heterocyclic residue having 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, and a is 0 or 1.
• Examples of the alkyl group having 1 to 30 carbon atoms represented by R 2 may include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, icosyl, docosyl, tetracosyl, hexacosyl, and octacosyl groups. These alkyl groups may be either straight or branched.
• Examples of the alkylene group having 1 to 30 carbon atoms represented by R may include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, and octadecylene groups. These alkylene groups may be either straight or branched.
• Examples of the amine residue represented by E may include dimethylamino, diethylamino, dipropylamino, dibutylamino, anilino, toluidino, xylidino, acetylamino, and benzoylamino groups.
• Examples of the heterocyclic residue represented by E may include morpholino, pyrrolyl, pyrrolino, pyridyl, methylpyridyl, pyrrolidinyl, piperidinyl, quinonyl, pyrrolidonyl, pyrrolidono, imidazolino, and pyrazino groups.
• Examples of the monomers represented by the formula (1a) may include the following monomers (Ba) to (Be).
• Monomer (Ba) is a (meth) acrylate having an alkyl group with 1 to 4 carbon atoms, and may specifically be methyl(meth)acrylate, ethyl(meth)acrylate, n- or i-propyl(meth)acrylate, n-, i-, or sec-butyl (meth) acrylate, with methyl(meth)acrylate being preferred.
• Monomer (Bb) is a (meth)acrylate having an alkyl or alkenyl group with 5 to 15 carbon atoms, and may specifically be octyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, undecyl(meth)acrylate, dodecyl(meth)acrylate, tridecyl(meth)acrylate, tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, octenyl(meth)acrylate, nonenyl(meth)acrylate, decenyl(meth)acrylate, undecenyl(meth)acrylate, dodecenyl(meth)acrylate, tridecenyl(meth)acrylate, tetradecenyl(meth)acrylate, or pentadecenyl(meth)acrylate. These may be either straight or branched. (Meth
• Monomer (Bc) is a (meth) acrylate having a straight alkyl or alkenyl group with 16 to 30 carbon atoms, preferably a straight alkyl group with 16 to 20 carbon atoms, more preferably a straight alkyl group with 16 or 18 carbon atoms.
• monomer (Bc) may include n-hexadecyl(meth)acrylate, n-octadecyl(meth)acrylate, n-icosyl(meth)acrylate, n-docosyl(meth)acrylate, n-tetracosyl(meth)acrylate, n-hexacosyl(meth)acrylate, and n-octacosyl(meth)acrylate, with n-hexadecyl(meth)acrylate and n-octadecyl(meth)acrylate being preferred.
• Monomer (Bd) is a (meth) acrylate having a branched alkyl or alkenyl group with 16 to 30 carbon atoms, preferably a branched alkyl group with 20 to 28 carbon atoms, more preferably a branched alkyl group with 22 to 26 carbon atoms.
• monomer (Bd) may include branched hexadecyl(meth)acrylate, branched octadecyl(meth)acrylate, branched icosyl(meth)acrylate, branched docosyl(meth)acrylate, branched tetracosyl(meth)acrylate, branched hexacosyl(meth)acrylate, and branched octacosyl(meth)acrylate.
• (Meth)acrylates represented by the formula -C-C(R 3 )R 4 having a branched alkyl group with 16 to 30, preferably 20 to 28, more preferably 22 to 26 carbon atoms are preferred.
• R 3 and R 4 are not particularly limited as long as the carbon number of -C-C (R 3 ) R 4 is 16 to 30, and R 3 may preferably be a straight alkyl group having 6 to 12, more preferably 10 to 12 carbon atoms, and R 4 may preferably be a straight alkyl group having 10 to 16, more preferably 14 to 16 carbon atoms.
• monomer (Bd) may include (meth)acrylates having a branched alkyl group with 20 to 30 carbon atoms, such as 2-decyl-tetradecyl (meth) acrylate, 2-dodecyl-hexadecyl(meth)acrylate, and 2-decyl-tetradecyloxyethyl(meth)acrylate.
• (meth)acrylates having a branched alkyl group with 20 to 30 carbon atoms such as 2-decyl-tetradecyl (meth) acrylate, 2-dodecyl-hexadecyl(meth)acrylate, and 2-decyl-tetradecyloxyethyl(meth)acrylate.
• Monomer (Be) is a monomer having a polar group.
• Examples of monomer (Be) may include vinyl monomers having an amido group, monomers having a nitro group, vinyl monomers having a primary to tertiary amino group, or vinyl monomers having a nitrogen-containing heterocyclicgroup;chlorides, nitrides, or phosphates thereof; lower alkyl monocarboxylates, such as those having 1 to 8 carbon atoms, vinyl monomers having a quaternary ammonium salt group, amphoteric vinyl monomers containing oxygen and nitrogen, monomers having a nitrile group, vinyl aliphatic hydrocarbon monomers, vinyl alicyclic hydrocarbon monomers, vinyl aromatic hydrocarbon monomers, vinyl esters, vinyl ethers, vinyl ketones, vinyl monomers having an epoxy group, vinyl monomers having a halogen, unsaturated carboxylates, vinyl monomers having a hydroxyl group, vinyl monomers having a polyoxyalkylene chain, vinyl monomers having an i
• monomers containing nitrogen are preferred among these, which may be, for example, 4-diphenylamine (meth)acrylamide, 2-diphenylamine (meth)acrylamide, dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, morpholinomethyl methacrylate, morpholinoethyl methacrylate, 2-vinyl-5-methylpyridine, or N-vinylpyrrolidone.
• 4-diphenylamine (meth)acrylamide 2-diphenylamine (meth)acrylamide, dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, dimethyl
• Component (B) in the present invention may preferably be a viscosity index improver containing a poly(meth)acrylate compound obtained by polymerizing or copolymerizing one or more monomers selected from above monomers (Ba) to (Be).
• poly(meth)acrylate compound More preferred examples of such poly(meth)acrylate compound may include:
• non-dispersant type poly(meth)acrylate compounds 1) to 3) above are more preferred, and non-dispersant type poly(meth)acrylate compounds 2) and 3) are still more preferred, and non-dispersant type poly (meth) acrylate compound 3) is particularly preferred.
• component (B) is usually provided in a state wherein the poly (meth) acrylate compound has been diluted to about 10 to 80 mass% with a diluent in light of easy handling and solubility in lubricant base oil (A) .
• the content of component (B) including the diluent is 1 to 20 mass%, preferably 2 to 12 mass%, more preferably 3 to 8 mass% of the total amount of the composition.
• component (B) If the content of component (B) is over the above range, improvement in anti-fatigue performance in proportion to the content may not be expected, shear stability is poor, the initial extreme pressure property is hard to be maintained for a prolonged period of time, and the effect on fuel efficiency resulting from the reduction of viscosity may be lowered.
• component (B) may suitably be selected from the above range depending on the kind of the poly (meth) acrylate compound or the ratio of the diluent, so that the kinematic viscosity at 100 °C of the present composition is 5.6 to 5.8 mm 2 /s.
• component (C) is an imide friction modifier having a hydrocarbon group with 8 to 30 carbon atoms.
• Component (C) is not particularly limited as long as it is a compound having an imide structure and a hydrocarbon group with 8 to 30 carbon atoms, and may preferably be, for example, a succinimide represented by the formula (2) or (3) and/or a derivative thereof:
• R 5 stands for a straight or branched hydrocarbon group having 8 to 30 carbon atoms
• R 6 stands for a hydrogen atom or a straight or branched hydrocarbon group having 1 to 30 carbon atoms
• R 7 stands for a hydrocarbon group having 1 to 4 carbon atoms
• m is an integer of 1 to 7.
• R 8 and R 9 independently stand for a straight or branched hydrocarbon group having 8 to 30 carbon atoms
• R 10 and R 11 independently stand for a hydrocarbon group having 1 to 4 carbon atoms
• n is an integer of 1 to 7.
• R 5 in the formula (2) and R 8 and R 9 in the formula (3) independently stand for a straight or branched hydrocarbon group having 8 to 30, preferably 12 to 25 carbon atoms.
• a hydrocarbon group may include alkyl and alkenyl groups, with an alkyl group being preferred.
• the alkyl and alkenyl groups may include octyl, octenyl, nonyl, nonenyl, decyl, decenyl, dodecyl, dodecenyl, octadecyl, and octadecenyl groups, as well as straight or branched alkyl group having up to 30 carbon atoms.
• the hydrocarbon group is a branched alkyl group having 8 to 30, more preferably 10 to 25 carbon atoms. With a branched alkyl group having 8 to 30 carbon atoms, deterioration of torque capacity of various wet clutches may be decreased compared to the case with a straight alkyl group, and a composition excellent in both capability of maintaining torque capacity and sustainability of anti-shudder property, may be obtained.
• R 7 in the formula (2) and R 10 and R 11 in the formula (3) independently stand for a hydrocarbon group having 1 to 4 carbon atoms.
• the hydrocarbon group may be an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 2 or 3 carbon atoms, such as an ethylene or propylene group.
• R 6 in the formula (2) may be, for example, a straight or branched alkyl or alkenyl group having 1 to 30 carbon atoms, preferably a branched alkyl or alkenyl group having 1 to 30, more preferably 8 to 30, and particularly preferably 10 to 25 carbon atoms, with the branched alkyl group being particularly preferred.
• n and m each denote an integer of 1 to 7.
• n and m each preferably denote 1, 2, or 3, particularly preferably 1.
• the succinimide compound represented by the formula (2) or (3) may be prepared by a known method, for example, by reacting an alkyl or alkenyl succinic anhydride and polyamine.
• monosuccinimide represented by the formula (2) wherein R 6 is a hydrogen atom may be prepared, for example, by gradually adding dropwise 1 mole of succinic anhydride having a straight or branched alkyl or alkenyl group with 8 to 30 carbon atoms to 1 mole or more of polyamine, such as diethylenetriamine, triethylenetetramine, or tetraethylenepentamine, in a nitrogen atmosphere at 130 to 180 °C, preferably 140 to 175 °C, allowing to react for 1 to 10 hours, preferably 2 to 6 hours, and distilling off the unreacted polyamine.
• Monosuccinimide represented by the formula (2) wherein R 6 is a hydrocarbon group having 1 to 30 carbon atoms maybe prepared, for example, by reacting N-octadecyl-1,3-propanediamine and the succinic anhydride mentioned above in the same way as outlined above.
• Bissuccinimide represented by the formula (3) may be prepared by adding dropwise 0.5 mole of the polyamine mentioned above to 1 mole of the succinic anhydride mentioned above under the same conditions as outlined above, allowing to react in the same way, and evaporating the generated moisture.
• Examples of the derivatives of the succinimide represented by the formula (2) or (3) may include compounds resulting from modification of the succinimide with boric acid, phosphoric acid, carboxylic acid, or derivatives thereof, sulfuric compounds, or triazoles. Specific examples of and methods for producing the derivatives may be those specifically disclosed in JP-2002-105478-A .
• component (C) use of bis-type succinimide represented by the formula (3) is particularly preferred compared to use of mono-type succinimide represented by the formula (2), for its capability of giving higher sustainability of anti-shudder property to the composition.
• the content of component (C) is 2 to 4 mass%, preferably 2.5 to 3.5 mass% of the total amount of the composition.
• the sustainability of anti-shudder property may not be made to achieve the higher goal of the present invention, for example, 1000 hour or longer life of anti-shudder property, whereas at a content of more than 4 mass%, anti-fatigue performance may be impaired.
• Component (D) in the present composition is a phosphorus extreme pressure agent.
• component (D) may include monophosphates, diphosphates, and triphosphates, monophosphites, diphosphites, triphosphites, having an alkyl or aryl group with 3 to 30, preferably 4 to 18 carbon atoms, and amine or alkanolamine salts thereof.
• phosphates and phosphites having an alkyl group with 3 to 30 carbon atoms are preferred, and phosphites having an alkyl group with 3 to 30 carbon atoms are particularly preferred.
• the content of component (D) is 0.01 to 0.04 mass%, preferably 0.02 to 0.04 mass% of the total amount of the composition in terms of phosphorus. If the content of component (D) in terms of phosphorus is less than the above range, sustainability of anti-shudder property tends to be lowered, whereas if the content is over the above range, anti-fatigue performance tends to be impaired.
• component (E) is an ashless dispersant having at least one alkyl or alkenyl group of a number average molecular weight of not lower than 2000.
• component (E) may include succinimide, benzylamine, or polyamine ashless dispersants having at least one alkyl or alkenyl group of a number average molecular weight of not lower than 2000.
• succinimide ashless dispersants having at least one alkyl or alkenyl group are preferred, and bis-type succinimide ashless dispersants having at least two alkyl or alkenyl groups are particularly preferred.
• the number average molecular weight of the alkyl or alkenyl group may preferably be 2000 to 5000, more preferably 2100 to 3500, still more preferably 2200 to 3000.
• the alkyl or alkenyl group may be either straight or branched.
• succinimide having at least one alkyl or alkenyl group of a number average molecular weight of not lower than 2000 may include compounds represented by the formula (4-a) or (4-b):
• R 12 , R 13 , and R 14 independently stand for an alkyl or alkenyl group having a number average molecular weight of not lower than 2000, preferably 2000 to 5000, more preferably a poly(iso)butenyl group; r is an integer of 1 to 5, preferably 2 to 4; and s is an integer of 0 to 4, preferably 1 to 3.
• the above-mentioned succinimide includes so-called monosuccinimides represented by the formula (4-a) wherein succinic anhydride is added to one end of polyamine, and so-called bissuccinimides represented by the formula (4-b) wherein succinic anhydride is added to both ends of polyamine.
• succinimides represented by the formula (4-a) wherein succinic anhydride is added to one end of polyamine
• bissuccinimides represented by the formula (4-b) wherein succinic anhydride is added to both ends of polyamine either one of or a mixture of these succinimides may be contained, and bis-type succinimides composed mainly of the bissuccinimides are particularly preferred.
• the succinimide may be prepared by any process without particular limitation, for example, by reacting polybutene or polyisobutylene having a number average molecular weight of not lower than 2000 with maleic anhydride at 100 to 200 °C, and reacting the resulting poly(iso)butenyl succinate with polyamine.
• the polyamine may be, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine.
• benzylamine having at least one alkyl or alkenyl group of a number average molecular weight of not lower than 2000 may include compounds represented by the formula (4-c):
• R 15 stands for an alkyl or alkenyl group having a number average molecular weight of not lower than 2000, preferably 2000 to 5000, more preferably a poly(iso)butenyl group, and t is an integer of 1 to 5, preferably 2 to 4.
• the benzylamine represented by the formula (4-c) may be prepared by any process without particular limitation, for example, by reacting polyolefin, such as propylene oligomer, polybutene, or ethylene- ⁇ -olefin copolymer, with phenol to give alkylphenol, which is then reacted with formaldehyde and polyamine, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine, by the Mannich reaction or the like.
• polyolefin such as propylene oligomer, polybutene, or ethylene- ⁇ -olefin copolymer
• formaldehyde and polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine
• polyamine having at least one alkyl or alkenyl group with a number average molecular weight of not lower than 2000 may include compounds represented by the formula (4-d): R 16 -NH-(CH 2 CH 2 NH) q -H (4 - d)
• R 16 stands for an alkyl or alkenyl group having a number average molecular weight of not lower than 2000, preferably 2000 to 5000, more preferably a poly(iso)butenyl group, and q is an integer of 1 to 5, preferably 2 to 4.
• the polyamine represented by the formula (4-d) may be prepared by any process without particular limitation, for example, by chlorinating polyolefin, such as propylene oligomer, polybutene, or ethylene- ⁇ -olefin copolymer, and reacting with ammonia or polyamine, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine.
• polyolefin such as propylene oligomer, polybutene, or ethylene- ⁇ -olefin copolymer
• ammonia or polyamine such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine.
• Component (E) also includes derivatives of the above nitrogen-containing compounds, such as succinimide, benzylamine, or polyamine.
• derivatives may include so-called acid-modified compounds obtained by reacting, to the nitrogen-containing compounds, monocarboxylic acid having 2 to 30 carbon atoms, such as aliphatic acid, polycarboxylic acid having 2 to 30 carbon atoms, such as oxalic, phthalic, trimellitic, or pyromellitic acid, or anhydrides or esters thereof, alkylene oxide having 2 to 6 carbon atoms, or hydroxy(poly)oxyalkylenecarbonate or the like, to neutralize or amidify all or part of the residual amino and/or imino groups; so-called boron-modified compounds obtained by reacting, to the nitrogen-containing compounds, boroncompounds, suchasboricacid, boratesalts, orboronic esters, to neutralize or amidify all or part of the residual amino and/or imino groups; sulfur-
• boron-modified compounds of alkyl- or alkenylsuccinimide having a number average molecular weight of not lower than 2000 give finest anti-fatigue performance on gears, so that it is particularly preferred that component (E) contains such boron-modified compounds as an essential component.
• the mass ratio of boron to nitrogen (B/N ratio) of the boron-modified compounds of the nitrogen-containing compounds is not particularly limited, and may preferably be not lower than 0.1, more preferably not lower than 0.2, and preferably not higher than 0.6, more preferably not higher than 0.3.
• B/N ratio The mass ratio of boron to nitrogen
• the nitrogen content of component (E) is arbitrary, and may usually be 0.01 to 10 mass%, preferably 0.1 to 3 mass%, particularly preferably 0.2 to 1 mass%, in light of abrasion resistance, oxidation stability, and friction characteristics.
• the minimum content of component (E) is not lower than 0.01 mass%, preferably 0.02 mass% of the total amount of the composition in terms of nitrogen, while the maximum content is not higher than 0.04 mass%, preferably 0.035 mass% of the total amount of the composition in terms of nitrogen.
• component (E) If the content of component (E) is less than 0.01 mass%, durability of friction characteristics and torque capacity are hard to be maintained, and oxidation stability tends to be deteriorated. Even if the content is more than 0. 04 mass%, sufficient effect in proportion to the content is not achieved, and low-temperature fluidity of the composition or anti-fatigue performance on gears may be deteriorated, thus not being preferred.
• a boron-modified compound of the nitrogen-containing compound is essentially contained as component (E)
• the minimum content thereof is not lower than 0.003 mass%, preferably not lower than 0.004 mass% of the total amount of the composition in terms of boron, while the maximum content thereof is not higher than 0.01 mass%, preferably not higher than 0.008 mass% of the total amount of the composition in terms of boron.
• boron-modified compound as component (E) With the content of the boron-modified compound as component (E) within the above-mentioned preferred range in terms of boron, durability of friction characteristics, torque capacity, low-temperature fluidity, and anti-fatigue performance on gears may be maintained at high levels in good balance.
• the viscosity index of the present composition is preferably 95 to 200, more preferably 150 to 180 for excellent viscosity-temperature characteristics. Further, a suitable kinematic viscosity at 40 °C of the composition is 25 to 30 mm 2 /s.
• the present composition in order to further improve its performance, or to impart performances necessary as a lubricant oil for automatic transmissions, may optionally contain various additives, such as viscosity index improvers, friction modifiers other than component (C), extreme pressure agents other than component (D), dispersants other than component (E), metal detergents, antioxidants, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, pour point depressants, seal swelling agents, foam inhibitors, and coloring agents, alone or in combination, as necessary.
• various additives such as viscosity index improvers, friction modifiers other than component (C), extreme pressure agents other than component (D), dispersants other than component (E), metal detergents, antioxidants, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, pour point depressants, seal swelling agents, foam inhibitors, and coloring agents, alone or in combination, as necessary.
• viscosity index improver may include known non-dispersant or dispersant type polymethacrylates (other than component (B)), non-dispersant or dispersant type ethylene- ⁇ -olefin copolymers or hydrides thereof, polyisobutylene or hydrides thereof, styrene-diene hydrogenated copolymers, styrene-maleic anhydride ester copolymers, and polyalkylstyrenes.
• the content of the viscosity index improver other than component (B), if contained, in the present composition is not particularly limited as long as the conditions of the kinematic viscosity at 100 °C of the composition is fulfilled, and may usually be 0.1 to 15 mass%, preferably 0.5 to 5 mass% of the total amount of the composition.
• the friction modifier other than component (C) may be any compound usually used as a friction modifier for a lubricant, and may preferably be, for example, amine compounds, fatty acids, fatty acid esters, fatty acid amides, or fatty acid metal salts, having in their molecule at least one alkyl or alkenyl group having 6 to 30 carbon atoms, preferably at least one straight alkyl or alkenyl group having 6 to 30 carbon atoms.
• any one or more compounds selected from the friction modifiers mentioned above may be contained at any content, which may usually be 0.01 to 5.0 mass%, preferably 0.03 to 3.0 mass% of the total amount of the composition.
• an extreme pressure agent composed of at least one sulfur extreme pressure agent selected from the group consisting of sulfurized oils and fats, sulfurized olefins, dihydrocarbyl polysulfides, dithiocarbamates, thiadiazoles, and benzothiazoles, and/or at least one phosphorus-sulfur extreme pressure agent selected from the group consisting of thiophosphorous acids, thiophosphorous monoesters, thiophosphorous diesters, thiophosphorous triesters, dithiophosphorous acids, dithiophosphorous monoesters, dithiophosphorous diesters, dithiophosphorous triesters, trithiophosphorous acids, trithiophosphorous monoesters, trithiophosphorous diesters, trithiophosphoroustriesters, and salts thereof.
• sulfur extreme pressure agent selected from the group consisting of sulfurized oils and fats, sulfurized olefins, dihydrocarbyl polysulfides, dithiocarbamates, thiadiazoles, and
• the content of the extreme pressure agent other than component (D), if contained, in the present composition may suitably be selected depending on its kind.
• the dispersant other than component (E) maybe an ashless dispersant, such as succinimide, benzylamine, polyamine, and/or boron compound derivatives thereof, having a hydrocarbon group with 40 to 400 carbon atoms, other than component (E).
• an ashless dispersant such as succinimide, benzylamine, polyamine, and/or boron compound derivatives thereof, having a hydrocarbon group with 40 to 400 carbon atoms, other than component (E).
• any one or more compounds selected from the dispersants mentioned above may be contained at any content, which may usually be 0.01 to 15 mass%, preferably 0.1 to 8 mass% of the total amount of the composition.
• metal detergents may include alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates.
• any one or more compounds selected from the metal detergents mentioned above may be contained at any content, which may usually be 0.01 to 10 mass%, preferably 0.1 to 5 mass% of the total amount of the composition.
• the antioxidants may be those commonly used for lubricants, such as phenol or amine compounds.
• antioxidants may include alkylphenols, such as 2,6-di-tert-butyl-4-methylphenol, bisphenols, such as methylene-4,4-bisphenol(2,6-di-tert-butyl-4-methylphenol), naphthylamines, such as phenyl- ⁇ -naphthylamine, dialkyldiphenylamines, zinc dialkyl dithiophosphates, such as zinc di-2-ethylhexyl dithiophosphate, and esters of (3,5-di-tert-butyl-4-hydroxyphenyl) fatty acid (such as propionic acid) or (3-methyl-5-tert-butyl-4-hydroxyphenyl) fatty acid (such as propionic acid) and monohydric or polyhydric alcohols, such as methanol, octanol, octadecanol, 1,6-hexadiol, neopentyl glycol,
• any one or more of the compounds selected from the above may be contained at any content, which may usually be 0.01 to 5 mass%, preferably 0.1 to 3 mass% of the total amount of the composition.
• corrosion inhibitor examples include benzotriazol, tolyltriazole, thiadiazole, and imidazole compounds.
• Examples of the rust inhibitor may include petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinates, and esters of polyhydric alcohols.
• demulsifier may include polyalkylene glycol nonionic surfactants, such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylnaphthyl ethers.
• polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylnaphthyl ethers.
• metal deactivator may include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazolepolysulfides, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamates, 2-(alkyldithio)benzoimidazoles, and ⁇ -(o-carboxybenzylthio)propionitrile.
• the pour point depressant may be selected from known pour point depressants depending on the lubricant base oil, and may preferably be polymethacrylates having a weight average molecular weight of 20000 to 500000, more preferably 50000 to 300000, particularly preferably 80000 to 200000.
• the foam inhibitor may be any compound usually used as a foam inhibitor for lubricants, for example, silicones, such as dimethyl silicon or fluorosilicon.
• the seal swelling agent may be any compound usually used as a seal swelling agent for lubricants, for example, ester, sulfur, or aromatic seal swelling agents.
• the coloring agent may be any compound usually used, and may be contained at any content, which may usually be 0.001 to 1.0 mass% of the total amount of the composition.
• the contents of the above additives, if contained, in the present composition are: 0.005 to 5 mass% for the corrosion inhibitors, rust inhibitors, or demulsifiers; 0.005 to 2 mass% for the pour point depressants or metal deactivators; 0.01 to 5 mass% for the seal swelling agents; and 0.0005 to 1 mass% for the foam inhibitors.
• Lubricant compositions for automatic transmissions of the present invention (Examples 1 to 3) were prepared with the compositions shown in Table 1. The following performance evaluation tests were conducted on these compositions. The results are also shown in Table 1.
• Lubricant compositions for automatic transmissions for comparison (Comparative Examples 1 to 9) were also prepared with the compositions shown in Table 1. The same performance evaluation tests were conducted on these compositions. The results are shown in Table 1.
• the low velocity friction test was conducted at an oil temperature of 120 °C during the durability test to evaluate the life of the anti-shudder property of the compositions of Examples and Comparative Examples.
• the life of the reference oil provided in this test procedure is 72 hours, so that the life of the anti-shudder property equivalent to or longer than this is determined to be excellent.
• the present invention aimed at 1000 hour or longer life, and after 1500 hours, the test was discontinued.
• test oils were subjected to forced degradation by ISOT test (150 °C, 96 hours) in accordance with JIS K 2514, and the increase in acid number (mgKOH/g) was measured.
• the clutch was idled at 3000 rpm with an inertial mass of 0.5 kg ⁇ m 2 , and then pressed with applied pressure to stop the rotation.
• the friction coefficient was calculated from the torque generated at a relative revolution of 1200 rpm of the clutch, and recorded.
• the cycle number at which the kinematic friction coefficient was decreased for 0.02 or more from the average kinematic friction coefficient of 1 to 100 cycles was taken as a durable life cycle of each composition.
• the durability was evaluated as extremely excellent at 8000 cycles or more, and the test was discontinued at 12000 cycles.
• the transmission was overhauled every 1000000 cycles, and the cycle number at which pitching occurred was taken as the life.
• the lubricant compositions for automatic transmissions according to the present invention (Examples 1 to 3) containing the particular amounts of components (A) to (E) of the present invention provided long fatigue life irrespective of their low viscosity, exhibited excellent sustainability of anti-shudder property, low-temperature viscosity characteristics, and oxidation stability, and were excellent and balanced in durability of friction characteristics, energy-conserving performance, and anti-fatigue performance on gears.
• the components defined in the present invention were not contained in good balance, any one or more of the above performances were not satisfactory (Comparative Examples 1 to 9).

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