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
  • C10M141/00—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential
  • C10M141/06—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential at least one of them being an organic nitrogen-containing compound
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  • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/02—Hydroxy compounds
  • C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/026—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings with tertiary alkyl groups
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/10—Carboxylix acids; Neutral salts thereof
  • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
  • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
  • C10M2207/126—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/26—Overbased carboxylic acid salts
  • C10M2207/262—Overbased carboxylic acid salts derived from hydroxy substituted aromatic acids, e.g. salicylates
• • 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
  • C10M2215/02—Amines, e.g. polyalkylene polyamines; Quaternary amines
  • C10M2215/06—Amines, e.g. polyalkylene polyamines; Quaternary amines having amino groups bound to carbon atoms of six-membered aromatic rings
  • C10M2215/064—Di- and triaryl amines
• • 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 [having hydrocarbon substituents containing less than thirty 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
  • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions
  • C10M2215/24—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions having hydrocarbon substituents containing thirty or more carbon atoms, e.g. nitrogen derivatives of substituted succinic acid
  • 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
  • C10M2219/00—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions
  • C10M2219/04—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions containing sulfur-to-oxygen bonds, i.e. sulfones, sulfoxides
  • C10M2219/046—Overbased sulfonic acid salts
• • 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
  • 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
  • C10N2030/40—Low content or no content compositions
  • C10N2030/42—Phosphor free or low phosphor 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
  • C10N2030/40—Low content or no content compositions
  • C10N2030/43—Sulfur free or low sulfur 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
  • C10N2030/40—Low content or no content compositions
  • C10N2030/45—Ash-less or low ash content
• • 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
  • C10N2030/54—Fuel economy
• • 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
  • C10N2040/252—Diesel engines

Definitions

• the present invention relates to a lubricating oil composition for lubricating internal combustion engines, particularly, a diesel engine. More specifically, the invention relates to a lubricating oil composition suitably employable for lubricating a diesel engine mounted to a car driven using fuel of a low sulfur content and enabling operation of the diesel engine with high fuel economy.
• Conventional lubricating oil compositions employed for lubricating a gasoline engine or a diesel engine generally comprise a major amount of a base oil having a lubricating viscosity and various additive components, depending upon specific function or formulators requirements.
• additive components include a metal-containing detergent, metal containing multifunctional addititves, ashless compounds such as ashless dispersant, oxidation inhibitors, etc.
• the metal-containing detergent has a function to neutralize sulfuric acid produced by burning fuel and is necessarily incorporated into a lubricating oil composition for lubricating a diesel engine which uses a fuel having a higher sulfur content as compared with a fuel used for a gasoline engine.
• the metal-containing detergent is incorporated into a lubricating oil composition for diesel engines in an amount of TBN (total base number) in the range of 2 to 15 mg•KOH/g.
• Zinc dithiophosphates (particularly, zinc dihydrocarbyldithiophosphate and zinc dialkyldithiophosphoate) which have multiple functions such as wear inhibition and extreme pressure resistance have been almost necessarily employed for preparation of the lubricating oil composition for diesel engines.
• zinc dihydrocarbylphosphate has been recently developed as a multi-functional additive replacing the zinc dithophosphate.
• the above-mentioned multi-functional additives have a drawback in having all of a metal element, a sulfur element, and a phosphorus element. Therefore, it is necessary to limit the amount of these multi-functional additives when the lubricating oil compositions having a low sulfated ash content, a low sulfur content, and a low phosphorus content are formulated.
• sulfur-containing organic molybdenum compound friction modifiers such as molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP) show a practically satisfactory friction modifying function and hence are used widely.
• MoDTC molybdenum dithiocarbamate
• MoDTP molybdenum dithiophosphate
• the sulfur-containing organic molybdenum compound friction modifiers also have drawbacks in having a metal element and a sulfur element.
• the sulfur-containing organic molybdenum compound friction modifiers have additional drawbacks in that the friction reducing function disappears within a relatively short period of time, additionally these compounds are quickly rendered ineffective with soot loading.
• Japanese Patent Provisional Publication 2004-155881 describes a fuel economy-type lubricating oil composition for internal combustion engines.
• the lubricating oil composition is prepared by combining a base oil having a viscosity index of 110 or more, a whole aromatic component content in the range of 2 to 15 wt.% and a sulfur content of 0.05 wt.% or more and a mixture of 1.2 to 5.0 wt.% of a fatty acid ester-type ashless friction modifier and/or a fatty amine-type ashless friction modifier and 0.02 to 0.15 wt.% (in terms of phosphorus content) of zinc dialkyldithiophosphate. It is described that the disclosed lubricating oil composition shows an improved friction reducing function, an improved wear resistance, and an improved storage stability. However, these types of frictions modifers have not been found to be effective at higher soot loading in the engines oil.
• the lubricating oil composition of the invention has a low sulfated ash content, a low phosphorus content and a low sulfur content and show an excellent friction-modifying function (friction -reducing function) even in the case in that a large amount of soots have migrated in the lubricating oil composition Further, the lubricating oil composition of the invention causes no corrosion of the metallic engine parts.
• the corrosion of the metallic engine parts is a problem known in the lubricating oil compositions containing an amine compound and a fatty acid.
• a lubricating oil composition for lubricating internal combustion engines which has a sulfated ash content of 1.1 wt.% or less, a sulfur content of 0.5 wt.% or less, and a phosphorus content of 0.12 wt.% or less and which comprises a base oil having a lubricating viscosity and the following additive components:
• the lubricating oil composition of the invention is favorably employable for lubricating diesel engines mounted to cars which are driven using a low sulfur fuel. Moreover, the lubricating oil composition of the invention is very advantageous as a lubricating oil composition for lubricating diesel engines demonstrating high fuel economy. Particularly for diesel engines which are expected to experience a high soot loading in the lubricating oil, such as for diesel engines equipped with EGR system or a diesel engine using a lubricating oil with a long service period, the lubricating oil compositions of the present invention can extend the service life and maintain the fuel economy.
• a preferred friction modifier is a neutralized salt of a fatty acid having 8 to 30 carbon atoms and a fatty amine having 8 to 30 carbon atoms.
• the fatty acid is an unsaturated fatty acid, such as a linear chain fatty acid, more preferably oleic acid; while the fatty amine is a saturated linear chain fatty amine, more preferably stearyl amine.
• the neutral salt of a fatty acid with a fatty amine is contain in an amount to provide a friction modifying effect, more preferably in an amount of 0.1 to 2 wt.%. Soot loading in the lubricating oil composition can be greater than 0.5 wt%, such as greater than 1 wt%, or greater than 2 wt%, up to about 5 wt%.
• the lubricating oil composition of the invention is also advantageous as a lubricating oil composition for lubricating gasoline engines with high fuel economy.
• the present invention is directed in part to fuel economy lubricating oil compositions particularly suited for diesel engines. More specifically the components have been selected to impart a high friction modifying function (high friction reducing function) in the use for lubricating diesel engines, particularly diesel engines mounted to cars driven using a low sulfur content diesel fuel.
• a high friction modifying function high friction reducing function
• a lubricating oil composition for gasoline engines and a lubricating oil composition for diesel engines both are classified into a lubricating oil composition for internal combustion engines, there are some differences in the required lubricating functions. For instance, in the case of a lubricating oil composition for diesel engines, there is a problem in that produced soots likely migrate into the lubricating oil. The soots easily agglutinate to form hard solid mass, which disturbs lubrication in the engine. The resulting lowering of lubricating function causes decrease of fuel economy.
• the lubricating oil composition should show enough friction modifying function (friction reducing function) less influenced by the migration of soots.
• the conventionally employed zinc dithiophosphate should not be used in a large amount.
• a lubricating oil composition for lubricating internal combustion engines which has a sulfated ash content of 1.1 wt.% or less, a sulfur content of 0.5 wt.% or less, and a phosphorus content of 0.12 wt.% or less and which comprises a base oil having a lubricating viscosity and the following additive components:
• the base oil of the lubricating oil composition according to the invention is a mineral oil and/or a synthetic oil which has a saturated component of 85 wt.% or more (preferably 90 wt.% or more), a viscosity index of 110 or more (preferably 120 or more, more preferably 130 or more), and a sulfur content of 0.01 wt.% or less (preferably 0.001 wt.% or less).
• the mineral oil preferably is an oil which is obtained by processing a lubricating oil distillate of a mineral oil by solvent refining, hydrogenation, or their combination.
• a highly hydrogenated refined oil corresponding to a hydrocracked oil, typically has a viscosity index of 120 or more, an evaporation loss (ASTM D5800) of 15 wt.% or less, a sulfur content of 0.01 wt.% or less, and an aromatic component content of 10 wt.% or less).
• the hydrocracked oil includes a high viscosity index oil (such as having a viscosity index of 140 or more, specifically 140 to 150) which is obtained by subjecting mineral oil-origin slack wax or synthetic wax prepared from natural gas to isomerization and hydrocracking and a gas-to-liquid base oil.
• the hydrocracked oil has a low sulfur content and a low residual carbon content and shows a low evaporation property, and therefore is preferred for the use in the lubricating oil composition of the invention.
• synthetic oils examples include poly- ⁇ -olefin such as a polymerized compound of ⁇ -olefin having 3 to 12 carbon atoms; a dialkyl ester of a di-basic acid such as sebacic acid, azelaic acid, or adipic acid and an alcohol having 4 to 18 carbon atoms, typically dioctyl sebacate; a polyol ester which is an ester of 1,1,1-trimethylolpropane or pentaerythritol and a mono-basic acid having 3 to 18 carbon atoms; and alkylbenzene having an alkyl group of 9 to 40 carbon atoms.
• poly- ⁇ -olefin such as a polymerized compound of ⁇ -olefin having 3 to 12 carbon atoms
• a dialkyl ester of a di-basic acid such as sebacic acid, azelaic acid, or adipic acid and an alcohol having 4 to 18 carbon atoms, typically dio
• the synthetic oil generally contains essentially no sulfur, shows good stability to oxidation and good heat resistance, and gives less residual carbon and soot when it is burned. Therefore, the synthetic oil is preferably employed for the lubricating oil composition of the invention. Particularly preferred is poly- ⁇ -olefin, from the viewpoint of the object of the invention.
• Each of the mineral oil and synthetic oil can be employed singly. If desired, two or more mineral oils can be employed in combination, and two or more synthetic oils can be employed in combination. The mineral oil and synthetic oil can be employed in combination at an optional ratio.
• the lubricating oil composition of the invention contains as the metal-containing detergent an alkylsalicylate and/or an alkylcarboxylate of an alkali metal or an alkaline earth metal.
• the metal-containing detergent comprises an alkylsalicylate and/or an alkylcarboxylate of an alkali metal or an alkaline earth metal.
• the alkylsalicylate and/or alkylcarboxylate may be employed in combination with a sulfonate and/or a phenate of an alkali metal or an alkaline earth metal.
• the alkylsalicylate and/or alkylcarboxylate of an alkali metal or an alkaline earth metal functions to increase dispersion of the soots and assists reduction of friction.
• alkylsalicylate and an alkylcarboxylate of an alkaline earth metal Preferred are an alkylsalicylate and an alkylcarboxylate of an alkaline earth metal.
• the alkaline earth metal preferably is calcium, barium, or magnesium. Calcium is most preferred.
• the alkaline earth metal-containing salicylate generally is a an alkaline earth metal salt of an alkyl-salicylic acid, which can be prepared from an alkylphenol by Kolbe-Schmidt reaction.
• the alkylphenol is obtained by a reaction of ⁇ -olefin having approx. 8 to 30 carbon atom (mean value) with phenol by Kolbe-Schmidt reaction.
• the alkaline earth metal salts can be ordinarily produced by subjecting their Na salt or K salt to double-decomposition or sulfuric acid decomposition, to give their Ca salt or Mg salt.
• the double decomposition using calcium chloride (CaCl 2 ) or the like is not preferred because chlorine is apt to migrate in the resulting product.
• an alkylphenol is directly neutralized to give its Ca salt, and then subjecting the Ca salt to a carbonation process to give the calcium salicylate.
• This process gives the desired compound in a low yield, in comparison with the Kolbe-Schmidt reaction. Therefore, it is preferred to combine the Kolbe-Schmidt reaction and sulfuric acid decomposition.
• a non-sulfurized alkylsalicylate alkaline earth metal salt having a TBN in the range of 30 to 300 mg•KOH/g.
• the alkaline earth metal carboxylate can be prepared, for instance, by neutralizing alkylphenol with an alkaline earth metal base in the presence of a carboxylic acid having 1 to 4 carbon atoms but in the absence of an alkali metal base, and carboxylating the resulting alkyl-phenate.
• the carboxylate can be a mono-aromatic ring hydrocarbylsalicylate-carboxylate which can be produced by treating an aromatic hydrocarbylsalicylate with a long chain carboxylic acid before, during, or after the aromatic hydrocarbylsalicylate is subjected to overbasing treatment. In these producing procedures, no Kolbe-Schmidt reaction (which includes production of an alkali metal salt) is performed. These producing procedures are described in Japanese Patent Provisional Publications 2000-63867 and 2000-87066 , incorporated herein by reference in their entirety.
• the nitrogen-containing ashless dispersant employed in the lubricating oil composition of the invention preferably has a weight average molecular weight or 4,500 to 20,000.
• the weight average molecular weight used in the specification is a molecular weight determined by GPC analysis using polystyrene as a reference compound.
• nitrogen-containing dispersants examples include alkenyl- or alkyl-succinimide or a derivative thereof which is derived from polyolefin.
• the nitrogen-containing dispersant is incorporated into the lubricating oil composition in an amount of 0.01 to 0.3 weight percent in terms of a nitrogen content, based on the total amount of the lubricating oil composition.
• a representative succinimide is obtained by the reaction between succinic anhydride having a substituent of an alkenyl group or an alkyl group which has a high molecular weight and polyalkylenepolyamine containing 4 to 10 nitrogen atoms (preferably 5 to 7 nitrogen atoms) per one molecule.
• the alkenyl group or an alkyl group which has a high molecular weight is preferably derived from polyolefin, particularly polybutene, having a number average molecular weight in the range of approx. 900 to 5,000.
• the process for obtaining the polybutenyl-succinic acid anhydride by the reaction of polybutene and maleic anhydride is generally performed by the chlorination process using a chloride compound.
• the chlorination process is advantageous in its reaction yield.
• the reaction product obtained by the chlorination process contains a large amount (for instance, approx. 2,000 ppm) of chlorine. If the thermal reaction process using no chloride compound is employed, the reaction product contains only an extremely small chlorine (for instance, 40 ppm or less).
• a highly reactive polybutene containing a methylvinylidene structure at least approx.
• the thermal reaction process can give a high reaction yield. If the reaction yield is high, the reaction product necessarily contains a reduced amount of the unreacted polybutene. This means that a dispersant containing a large amount of the effective component (succinimide) is obtained. Accordingly, it is preferred that the polybutenyl succinic acid anhydride is produced from the highly reactive polybutene by the thermal reaction and that the produced polybutenyl succinic acid anhydride is reacted with polyalkylenepolyamine having an average nitrogen atom number in the range of 4 to 10 (in one molecule) to give the succinimide.
• the succinimide further can be reacted with boric acid, alcohol, aldehyde, ketone, alkylphenol, cyclic carbonate, organic acid or the like, to give a modified succinimide.
• a borated alkenyl(or alkyl)-succinimide which is obtained by the reaction with boric acid or a boron compound is advantageous from the viewpoints of thermal and oxidation stability.
• nitrogen-containing ashless dispersants include polymeric succinimide dispersants derived from ethylene- ⁇ -olefin copolymer (for instance, the molecular weight is 1,000 to 15,000), and alkenyl-benzyl amine ashless dispersants.
• the nitrogen-containing ashless dispersant can be replaced with a nitrogen-containing dispersive viscosity index improver.
• a nitrogen-containing dispersive viscosity index improver a nitrogen-containing olefin copolymer or a nitrogen-containing polymethacrylate each having a weight mean molecular weight of 90,000 or more (in terms of polystyrene converted-molecular weight determined by GPC analysis). In consideration of thermal stability, the former is preferred.
• the lubricating oil composition of the invention necessarily contains a nitrogen-containing ashless dispersant and/or a nitrogen-containing dispersive viscosity index improver.
• the other ashless dispersants such as an alkenylsuccinic acid ester dispersant can be employed in combination.
• the lubricating oil composition of the invention contains a neutral salt (or neutralized salt) of a fatty acid and a fatty amine as a friction modifier (friction reducing agent).
• the fatty acid preferably is a linear chain fatty acid having 8 to 30 carbon atoms.
• the fatty amine preferably is a linear chain fatty amine having 8 to 30 carbon atoms. It is preferred that the fatty group of one of the fatty acid and fatty amine is an unsaturated group (e.g., oleyl). It is also preferred that the fatty group of both of the fatty acid and fatty amine is an unsaturated group (e.g., oleyl). It is further preferred for the neutral salt of fatty acid and fatty amine that a difference between the acid value (unit: mg•KOH/g) and the amine value (unit: mg•KOH/g) is not more than 20, specifically not more than 15.
• Examples of the preferred neutral salts of fatty acid and fatty amine include a salt of oleic acid with stearylamine, a salt of oleic acid with laurylamine, a salt of oleic acid with oleylamine, and a salt of a dioleic acid with N-oleylpropylenediamine.
• Both of the fatty acid and fatty amine can be employed their derivatives such as alkyleneoxide adducts or sulfides.
• the neutral acid salt of fatty acid and fatty amine according to the invention include salts of these derivatives.
• the oxidation inhibitor preferably is at least one oxidation inhibitor selected from the group consisting of the known phenolic oxidation inhibitor and the known amine oxidation inhibitor.
• a representative phenolic oxidation inhibitor is a hindered phenol compound, and a representative amine oxidation inhibitor is a diarylamine compound.
• the hindered phenol compound and diarylamine compound are advantageous because both further provide high detergency at a high temperature.
• the diarylamine oxidation inhibitor is particularly advantageous because it has a base number derived from the contained nitrogen which serves to increase detergency at a high temperature.
• the hindered phenol oxidation inhibitor is effective to reduce oxidative deterioration caused by NO x .
• hindered phenol oxidation inhibitors examples include 2,6-di-t-butyl-p-cresol, 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-methylenebis(6-t-butyl-o-cresol), 4,4'-isopropylidenebis(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-thiobis(2-methyl-6-t-butylphenol), 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydoxyphenyl)-propionate], octyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)prop
• diarylamine oxidation inhibitors examples include alkyldiphenylamine having a mixture of alkyl groups of 4 to 9 carbon atoms, p,p'-dioctyldiphenylamine, phenyl- ⁇ -naphthylamine, phenyl- ⁇ -naphthylamine, alkylated ⁇ -naphthylamine, and alkylated phenyl- ⁇ -naphthylamine.
• Each of the hindered phenol oxidation inhibitor and diarylamine oxidation inhibitor can be employed singly or in combination. If desired, other oil soluble oxidation inhibitors can be employed in combination with the hindered phenol oxidation inhibitor and/or the diarylamine oxidation inhibitor.
• the lubricating oil composition of the invention can further contain a basic nitrogen-containing compound-oxymolybdenum complex.
• a basic nitrogen-containing compound-oxymolybdenum complex include an oxymolybdenum complex of succinimide and an oxymolybdenum complex of carboxylamide.
• the basic nitrogen-containing compound-oxymolybdenum complex can be prepared by the following process:
• the lubricating oil composition of the invention may contain zinc dihydrocarbylditiophosphate or zinc dihydrocarbylphosphate both of which are known as multi-functional additives having an oxidation inhibition function and a friction reducing function. These additives can be incorporated into the lubricating oil composition in an amount of not more than 0.12 wt.% (in terms of phosphor content), preferably in the range of 0.01 to 0.12, more preferably in the range of 0.01 to 0.08.
• a zinc dialkyldithiophosphate having a primary or secondary alkyl group is used.
• a zinc dialkyldithiophosphate having a secondary alkyl group which is derived from a secondary alcohol having 3 to 18 carbon atoms is preferred in its excellent heat resistance and friction reducing function.
• the zinc dialkyldithiophosphate having a secondary alkyl group and the zinc dialkyldithiophosphate having a primary alkyl group can be used in combination.
• a zinc dialkyldithiophosphate having a primary alkyl group and a secondary alkyl group which can be obtained using a mixture of a primary alcohol and a secondary alcohol can also be favorably employed.
• a zinc dialkylaryldithiophosphate e.g., zinc dialkylaryldithiophosphate obtainable using dodecylphenol
• zinc dialkylaryldithiophosphate obtainable using dodecylphenol
• a zinc dihydrocarbylphosphate can be employed in place of the zinc dihyrocarbyldithiophosphate.
• the former zinc dihydrocarbylphosphate may be advantageous from the viewpoint of minimizing sulfur content, because it contains no sulfur atoms.
• molybdenum-containing compounds In combination with the basic nitrogen-containing compound-oxymolybdenum complex, other molybdenum-containing compounds can be used.
• molybdenum-containing compounds include sulfurized oxymolybdenum dithiocarbamate and sulfurized oxymolybdenum dithiophosphate.
• the lubricating oil composition of the invention may further contain an alkali metal borate hydrate for increasing stability at a high temperature and a basic number.
• the alkali metal borate hydrate can be contained in an amount of 5 wt.% or less, particularly 0.01 to 5 wt.%.
• Some alkali metal borate hydrates contain an ash component and a sulfur component. Therefore, the alkali metal borate hydrate can be used in an appropriate amount in consideration of the composition of the resulting lubricating oil composition.
• the lubricating oil composition of the invention preferably contains a viscosity index improver in an amount of 20 wt.% or less, preferably 1 to 20 wt.%.
• a viscosity index improver examples are polymers such as polyalkyl methacrylate, ethylene-propylene copolymer, styrene-butadiene copolymer, and polyisobutylene.
• a dispersant viscosity index improver and a multi-functional viscosity index improver which are produced by providing dispersant properties to the above-mentioned polymer are preferably employed.
• the viscosity index improvers can be used singly or in combination.
• the lubricating oil composition of the invention may further contain a small amount of various auxiliary additives.
• auxiliary additives are described below:
• the auxiliary additives can be preferably incorporated into the lubricating oil composition in an amount of 3 wt% or less (particularly, 0.001 to 3 wt.%).
• the lubricating oil composition of the invention is preferably formulated to give a multi-grade engine oil of a relatively low viscosity, such as 0W20, 0W30, 0W40, 5W20, 5W30, 5W40, 10W20, or 10W30 (SAE viscosity grade), by incorporating a viscosity index improver, from the viewpoint of fuel economy.
• SAE viscosity grade a relatively low viscosity
• a lubricating oil composition of the invention having an SAE viscosity grade of 5W20 was prepared using the following additives and base oil.
• Example 1 The procedures of Example 1 were repeated except that the friction modifier is not used, to give a lubricating oil composition for comparison.
• Example 1 The procedures of Example 1 were repeated except that the friction modifier was replaced with the same amount (0.6 wt.%) of a fatty acid (oleic acid), to give a lubricating oil composition for comparison.
• a fatty acid oleic acid
• Example 2 The procedures of Example 1 were repeated except that the friction modifier was replaced with the same amount (0.6 wt.%) of a fatty amine (stearyl amine), to give a lubricating oil composition for comparison.
• a fatty amine stearyl amine
• Example 1 The procedures of Example 1 were repeated except that the friction modifier was replaced with the same amount (0.6 wt.%) of a fatty acid ester (glycerol monooleate), to give a lubricating oil composition for comparison.
• a fatty acid ester glycerol monooleate
• Example 2 The procedures of Example 1 were repeated except that the friction modifier was replaced with the 1.1 wt.% of sulfurized oxymolybdenum dithiocarbamate (MoDTC, Mo: 4.5 wt.%, S: 4.7 wt.%), to give a lubricating oil composition for comparison.
• MoDTC sulfurized oxymolybdenum dithiocarbamate
• Example Comparison Example 1 The characteristics of the lubricating oil compositions obtained in Example 1 and Comparison Examples 1 to 5 are set forth in Table 1.
• Table 1 Example Comparison Example 1 1 2 3 4 5 Sulfated ash 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 N 0.14 0.12 0.12 0.16 0.12 0.13 Ca 0.26 0.26 0.26 0.26 0.26 0.26 P 0.08 0.08 0.08 0.08 0.08 S 0.20 0.20 0.20 0.20 0.27 TBN 10.4 9.8 9.8 10.9 9.8 9.9
• carbon black (mean particle diameter: 22 nm, specific surface area: 134 m 2 /g, carbon particles produced by incomplete combustion of fuel) in an amount of 0 wt.%, 1 wt.%, or 2 wt.%) was blended in the lubricating oil composition by means of a high speed agitator to give a test oil.
• the test oil containing carbon black was then subjected to the HFRR test by means of a HFRR tester under the conditions of 105°C for oil temperature, 400 g of load, 1,000 ⁇ m for friction length, 20 Hz for frequency of reciprocating motion, and one hour for test period, to determine a friction coefficient.
• Table 2 The results are set forth in Table 2.
• the corrosion of non-iron metal by the diesel engine oil was evaluated.
• the test was carried out by introducing air into the test oil containing copper, lead, and phosphor bronze at 135°C (oil temperature) for 168 hours.
• the amount of copper, lead and tin having been dissolved in the test oil was measured.
• the test results and criteria are set forth in Table 2.

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