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
  • C10M163/00—Lubricating compositions characterised by the additive being a mixture of a compound of unknown or incompletely defined constitution and a non-macromolecular compound, each of these compounds being essential
• • 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
  • C10M169/048—Mixtures of base-materials and additives the additives being a mixture of compounds of unknown or incompletely defined constitution, non-macromolecular and macromolecular compounds
• • 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
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/087—Boron oxides, acids or 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
  • 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
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/1006—Petroleum or coal fractions, e.g. tars, solvents, bitumen used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
  • C10M2205/0206—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/283—Esters of polyhydroxy compounds
  • C10M2207/2835—Esters of polyhydroxy compounds used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • 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
  • C10M2215/24—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
  • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
  • C10M2229/02—Unspecified siloxanes; Silicones
• • 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
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/04—Groups 2 or 12
• • 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
  • C10N2030/04—Detergent property or dispersant property
• • 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
  • 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
  • C10N2030/68—Shear stability

Definitions

• the present invention relates to a lubricating oil composition for internal combustion engines, more particularly a lubricating oil composition for internal combustion engines having a superlow-ash oil composition suitable for diesel engines equipped with an exhaust gas post-treatment device, e.g., diesel particulate filter (DPF) or catalytic system for simultaneously abating particulate matter and NOx (DPNR).
• an exhaust gas post-treatment device e.g., diesel particulate filter (DPF) or catalytic system for simultaneously abating particulate matter and NOx (DPNR).
• DPF diesel particulate filter
• DPNR catalytic system for simultaneously abating particulate matter and NOx
• lubricating oils for diesel engines generally contain a metal-base detergent and ashless dispersant as essential components, which may cause troubles, e.g., clogging and malfunctions of DPFs by a metal in oils. Reducing metal content may cause insufficient cleaning of engines.
• Patent Document 1 JP-A-8-253782 , Patent Document 1 discloses a lubricating oil composition for diesel engines, having a sulfated ash content of 1.5% by mass or less, wherein the composition comprises a lubricating base oil incorporated with additives of (a) boron-containing low-ash dispersant, (b) metal-base detergent agent and, as required, (c) ester of an aromatic carboxylic acid containing hydroxyl group and hydroxyl compound and/or boron-containing compound in a [B]/[M] mass ratio of 0.15 or more ([B]: boron content in the composition and [M]: content of total metals based on the metal-base detergent(s) in the composition).
• the composition is considered not to achieve sufficient reduction of metals judging from the description saying that it needs 0.18% by mass of calcium.
• Prior Art 2 JP-A-9-111275 , Patent Document 2 discusses that a combination of specific metal-base detergent and ashless dispersant achieves good characteristics, e.g., cleanability, for a lubricating oil having an ash content of 0.4 to 0.8% by mass. However, it still needs 0.07% of a metal-base detergent component to keep its cleanability.
• Prior Art 3 JP-A-2002-60776 , Patent Document 3) reduces the ash content in a low-sulfur oil composition incorporated with a Mo compound. This technique, however, aims at improved combustion of PM, and fails to achieve a superlow ash content viewed from prevention of DPF clogging, because it contains a metallic component derived from a metal-base detergent at around 0.2%.
• Patent Document 4 intends to secure good cleanability at a low ash content by use of specific calcium salicylate. However, it needs at least 0.03% by mass of calcium, as is the case with the conventional technique, and fails to sufficiently reduce an ash content to a low level. Under these situations, there are strong demands for oil compositions of lower ash content viewed from extending DPF serviceability, in consideration of exhaust gas regulations becoming increasingly stringent and future regulations on sub-micron particles.
• the inventors of the present invention have proposed a diesel engine oil composition which can secure low ash content and cleanability at high temperature by use of a heavy fraction having a GCD boiling temperature of 550°C or higher (hereinafter referred to as the GCD550°C + heavy fraction) contained at 6% by volume or more, instead of optimizing an additive composition (Prior Art 5, ( JP-A-2003-201496 , Patent Document 5).
• Patent Document 1 JP-A-8-253782
• Patent Document 2 JP-A-9-111275
• Patent Document 3 JP-A-2002-60776
• Patent Document 4 JP-A-2004-35652
• Patent Document 5 JP-A-2003-201496
• a superlow-ash lubricating oil composition for internal combustion engines substantially free of metal derived from a metal-base detergent or containing the metal at a very low content, can exhibit cleanability not only for a carbonaceous component deposited on a piston but also for a lacquer component deposited on lower-temperature portions in engines, in spite of its low viscosity, by incorporating the GCD550°C + heavy fraction at 6% by mass or more and, at the same time, a specific boron-base additive, achieving the present invention based on the above findings.
• the present invention provides a lubricating oil composition for internal combustion engines, characterized by containing the GCD550°C + heavy fraction at 6% by volume or more, and having a sulfated ash content of 0.6% by mass or less and content of an additive containing a boron-base compound of 0.02% by mass or more as boron.
• the present invention provides a lubricating oil composition for internal combustion engines, containing, as essential components, the GCD550°C + heavy fraction at 6% by volume or more and an additive containing a boron-base compound at 0.02% by mass or more as boron. It includes more preferable embodiments 1) to 8) described below.
• the lubricating oil composition of the present invention exhibits a notable effect for improving cleanability at high temperature in spite of its superlow-ash composition substantially free of a metal-base detergent , as discussed above.
• the present invention provides a suitable engine oil for diesel engines quipped with an exhaust gas post-treatment device, e.g., DPF, because it can prevent clogging of the DPF with ashes.
• the present invention provides a lubricating oil composition excellent in cleanability at high temperature in spite of its low viscosity and superlow-ash composition substantially free of a metal-base detergent.
• the lubricating oil composition for internal combustion engines is achieved by incorporating a lubricating oil with a base oil of high boiling point and an additive containing a boron-base compound, while using substantially no metal-base detergent.
• the present invention can provide a lubricating oil composition for internal combustion engines, having an SAE viscosity grade of 0W-20, 0W-30, 5W-20, 5W-30 or 10W-30, preferably 0W-20, 0W-30, 5W-20 or 5W-30.
• the present invention can provide a low-viscosity lubricating oil composition for internal combustion engines, having an HTHS viscosity of below 2.6 mPa ⁇ s at 150°C and a shear rate of 10 6 s -1 .
• the above characteristic (1) of "containing the GCD550°C + heavy fraction at 6% by volume or more” means that the composition can exhibit a notable effect of improving cleanability at high temperature when it contains the fraction at 6% by volume or more.
• the critical content has been confirmed by the panel coking test for measuring deposit formed, the results indicating that the effect sharply decreasing when the content is below 6% by volume.
• the upper content level is 50% by volume, preferably 25% by volume. At above 50% by volume, the viscosity-related properties at low temperature, cold startability and fuel economy may deteriorate.
• the "GCD550°C + heavy fraction" is determined by gas chromatography carried out by a procedure under conditions described later in Examples.
• the function of the GCD550°C + heavy fraction is not fully substantiated, but conceivably comes from its function of cleaning carbonaceous substance deposited on, e.g., upper portion of piston.
• the above characteristic (2) is a sulfated ash content of 0.6% by mass or less, preferably 0.5% by mass or less.
• the sulfated ash content means a constant mass of char resulting from combustion of sample oil, after it is treated with sulfuric acid under heating. The procedure for determining the sulfated ash content is described later in Examples. It is generally derived from a metal in a metal-base additive contained in a lubricating oil composition. It is necessary to limit it to 1.0% by mass, because a DPF tends to be clogged with ashes when a lubricating oil composition has a sulfated ash content exceeding 1.0% by mass.
• the present invention can further reduce the content to 0.6% by mass or less to provide a lubricating oil composition of superlow ash content.
• the characteristic (3) is a content of additive containing a boron-base compound of 0.02% by mass or more as boron. Incorporation of the lubricating oil composition with a boron-base compound at a specific content, i.e., 0.02% by mass or more as boron, notably improves cleanability of removing deposited lacquer, determined by the hot tube test carried out at 290°C.
• This characteristic coupled with the characteristic (1) of containing the GCD550°C + heavy fraction at 6% by volume or more, secures cleanability at high temperature over a wider range.
• the upper limit of a boron-base compound is set at 0.2% by mass as boron, preferably 0.1% by mass, because increasing boron content beyond the above level will lead to increased ash content.
• the boron-base compounds include boron-containing polyalkenyl succinimide and borate of an alkaline metal, which are described later in detail.
• a lubricating base oil as a component of the lubricating oil composition of the present invention contains a high-boiling fraction having fluidity at high temperature at a specific content. More specifically, it contains the GCD550°C + heavy fraction at 6% by volume or more based on the lubricating oil composition.
• the base oil having the specific properties can be produced by blending various base stocks.
• the base stock is not limited so long as it has a given fraction. It may be a mineral base oil, synthetic base oil, hydroisomerized/isomerized dewaxed base oil, gas-to-liquid (GTL) base oil, asphalt-to-liquid (ATL) base oil, vegetable base oil or a mixture thereof.
• the mineral base oil is produced by treating a lubricating oil fraction as a vacuum distillate from a paraffinic, intermediate or naphthenic crude.
• the treatment methods include solvent refining, hydrocracking, hydrogenation, hydrorefining, catalytic dewaxing and clay treatment.
• the mineral base oils useful for the present invention include solvent-refined raffinate or hydrotreated oil treated by one or more of the above methods; vacuum residue treated by solvent deasphalting and then by one or more of the above methods; isomerized wax; hydroisomerized/isomerized dewaxed oil; gas-to-liquid (GTL) oil; asphalt-to-liquid (ATL) oil; and a mixture thereof.
• the solvent refining may use an aromatic extraction solvent, e.g., phenol, fulfural, or N-methylpyrrolidone.
• the solvent dewaxing may use a solvent, e.g., liquefied propane or MEK/toluene.
• the catalytic dewaxing may use a dewaxing catalyst, e.g., shape-selective zeolite.
• the base oil for the present invention may be composed of, totally or partly, hydrodewaxed oil, mixed hydroisomerized/catalytic (or solvent) dewaxed base stock, mixed GTL base stock or a mixture thereof, preferably mixed GTL base stock.
• a lubricating oil fraction isolated from a liquid product from an ATL process which treats heavy residue component, e.g., asphalt may be also used.
• the above-described refined mineral oil, hydroisomerized/isomerized dewaxed base oil, GTL base oil and ATL base oil include light or medium neutral oil. These base oils can be adequately blended to satisfy the required properties, in order to produce the desired base oil for the present invention.
• Examples of synthetic base oils include:
• - ⁇ -olefin oligomer examples include homopolymers of ⁇ -olefin of 6 to 12 carbon atoms (e.g., 1-hexene, 1-octene and 1-decene polymers described above), and copolymers of mixed monomers, having a kinematic viscosity of 2 to 3000 mm 2 /s at 100°C.
• a liquid copolymer of ethylene and an ⁇ -olefin may be used as a base oil, selected from commercial viscosity grades of 8, 10, 20, 40, 100, 150, 600, 2000 mm 2 /s at 100°C, and so forth.
• polyol esters examples include those of hindered alcohol of 5 to 30 carbon atoms and fatty acid.
• the hindered alcohols include neopentyl glycol, 2,2-diethylpropane-1,3-diol, 2,2-dibutylpropane-1,3-diol, 2-methyl-2-propylpropane-1,3-diol, 2-ethyl-2-butylpropane-1,3-diol, trimethylol ethane, trimethylol propane, ditrimethylol propane, tritrimethylol propane, tetratrimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, tetrapentaerythritol and pentapentaerythritol.
• the preferable hindered alcohols have 5 to 20 carbon atoms, and the particularly preferable ones include trimethylol propane, ditrimethylol propane, tritrimethylol propane, pentaerythritol, dipentaerythritol and tripentaerythritol.
• Examples of the fatty acids include linear or branched ones of 4 to 20 carbon atoms.
• the linear fatty acids include n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic aicd, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid, n-hexadecanoic acid, n-heptadecanoic acid, n-octadecanoic acid, n-nonadecanoic acid and eicosanic acid.
• branched fatty acids examples include 2-methylpropanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-di-methylpropanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid, 2,3-dimethylbutanoic acid, 2-ethylpentanoic acid, 2,2-dimethylpentanoic acid, 2-ethyl-2-methylbutanoic acid, 3-methylhexanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 2-propylpentanoic acid, 2,2-dimethylhexanoic acid, 2-ethyl-2-methylpentanoic acid, 2-methyloctanoic acid, 2,2-dimethylheptanoic acid, 2-ethylheptanoic acid, 2-methylnonanoic acid, 2,2-dimethyloctanoic acid, 2-eth
• the hindered ester can be produced by conventional method, e.g., (a) direct esterification in which a polyol and fatty acid is dehydrated/condensed in the absence of catalyst or in the presence of acidic catalyst, (2) reaction of a fatty acid chloride with a polyol, or (3) transesterification between a lower alcohol/fatty acid ester and polyol ester.
• polyol esters examples include the following compounds, wherein neopentyl glycol, trimethylol propane, dimethylol propane, pentaerythritol, dipentaerythritol and tripentaerythritol are abbreviated by respective NPG, TMP, DTMP, PE, DPE and TPE.
• the base oil for the lubricant oil composition of the present invention for internal combustion engines can be produced from the above-described base stocks, which may be used either individually or in combination in such a way to secure desired properties, e.g., kinematic viscosity of 2 to 15 mm 2 /s at 100°C, preferably 3 to 13 mm 2 /s, and GCD550°C + heavy fraction content of 6 to 50% by volume, inclusive, based on the lubricating oil composition, preferably 25% by volume or less, more preferably 20% by volume or less.
• desired properties e.g., kinematic viscosity of 2 to 15 mm 2 /s at 100°C, preferably 3 to 13 mm 2 /s, and GCD550°C + heavy fraction content of 6 to 50% by volume, inclusive, based on the lubricating oil composition, preferably 25% by volume or less, more preferably 20% by volume or less.
• the present invention can provide a low-viscosity lubricating oil composition having an SAE viscosity grade of 0W-20, 0W-30, 5W-20, 5W-30 10W-30 or the like by adequately selecting one or more lubricant base oils. Moreover, it can provide a lubricating oil composition having an HTHS viscosity of below 2.6 mPa ⁇ s.
• SAE J300 SAE: US's Society of Automotive Engineers.
• Examples of the additive containing a boron-base compound as a component of the lubricating oil composition of the present invention for internal combustion engines include boron-containing dispersants based on polyalkenyl succinimide and additives based on potassium borate.
• Boron-containing dispersants based on polyalkenyl succinimide are produced by treating a mono or bis type polyalkenyl succinimide, represented by the respective general formulae (1) and (2), with a boron compound. These mono and bis succinimide types may be used in combination.
• the boron compounds include boric acid, boric anhydride, boron oxide, halogenated boron, boric acid ester and so forth.
• R 1 , R 3 and R 5 are each a polyalkenyl group, preferably polybutenyl group, having a number-average molecular weight of 800 to 2600, preferably 900 to 2400, which may be the same or different;
• R 2 and R 4 are each an alkylene group of 2 to 5 carbon atoms, which may be the same or different; and
• X is an integer of 1 to 10.
• the mono and bis type polyalkenyl succinimides are generally produced by the reaction between a polybutenyl succinic anhydride and polyamine, the former being produced by the reaction between polybutene and maleic anhydride.
• the polyamine include single diamines, e.g., ethylenediamine, propylenediamine, butylenediamine and pentylenediamine; and polyalkyene polyamines, e.g., diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine, dibutylenetriamine, tributylenetetramine and pentapentylenehexamoine.
• the boron-containing dispersant based on polyalkenyl succinimide preferably contains boron at 0.2% by mass or more.
• Each of the mono type represented by the general formula (1) and bis type represented by the general formula (2) may be used, the latter being more preferable.
• the additive based on borate of an alkaline metal containing a hydrated borate of an alkaline metal
• M is an alkaline metal
• x is 2.5 to 4.5
• y is 1.0 to 4.8
• examples of the compound include hydrated lithium borate, hydrated sodium borate, hydrated potassium borate, hydrated rubidium borate and hydrated cesium borate, of which hydrated potassium borate and hydrated sodium borate are more preferable, and hydrated potassium borate is particularly preferable.
• the hydrated borate generally has an average particle diameter of 1 ⁇ m or less.
• the alkaline metal borate for the present invention preferably has a boron/alkaline metal ratio in a range from about 2.5/1 to 4.5/1.
• a dispersion of hydrated alkaline metal borate in oil is generally produced by a process comprising steps for forming a solution of the alkaline metal hydroxide and boric acid in deionized water in the presence of an optional small quantity of alkaline metal carbonate; for incorporating the solution in a lubricant oil composition composed of a lubricant oil, dispersant and optional additive(s) to form an emulsion; and for dehydrating the emulsion.
• the present invention may also use a dispersion of fine particles of alkaline metal borate produced by a process comprising steps for carbonating an alkaline or alkaline-earth, neutral sulfonate in the presence of an alkaline metal hydroxide to form the ultrabasic sulfonate; and for reacting boric acid with the resulting sulfonate.
• the carbonation process may be carried out in the presence of an ashless dispersant, e.g., succinimide.
• the more preferable hydrated alkaline metal borate for the composition component are potassium borate and sodium borate in the form of dispersion, produced using neutral calcium sulfonate or an ashless dispersant, e.g., succinimide.
• the hydrated alkaline metal borates may be used either individually or in combination.
• the boron-base additive for the lubricating oil composition of the present invention for internal combustion engines may be the above-described boron-containing polyalkenyl succinimide, borate of an alkaline metal or a mixture thereof, of which the additive of borate of an alkaline metal is particularly preferable.
• the boron-base additive is incorporated at least at 0.02% by mass based on the whole lubricant oil composition. At a lower content, the composition may have insufficient cleanability, as demonstrated in Examples and Comparative Examples.
• the upper limit is preferably set at 0.2% by mass, above which sulfated ash content increases to possibly clog a DPF and viscosity-related properties of the composition may be deteriorated by the succinimide component.
• the lubricating oil composition of the present invention for internal combustion engines can be structured to exhibit sufficient cleanability at high temperature in the absence of a metal-base cleaning agent as a constituent, but will have improved cleanability in the presence of a detergent without substantially increasing sulfated ash content so long as it is incorporated at 0.1% by mass or less, preferably 0.01% by mass or less.
• the useful metal-base detergent is an alkaline-earth metal sulfonate, alkaline-earth salicylate, alkaline-earth phenate or a mixture thereof.
• An alkaline-earth sulfonate is a salt of sulfonic acid with an alkaline-earth metal, e.g., long-chain alkylbenzene, alkylnaphthalene or the like.
• An alkaline-earth salicylate is a salt of alkylsalicylic acid, which may be sulfided, with an alkaline-earth metal.
• An alkaline-earth phenate is a salt of alkylphenol, which may be sulfided, with an alkaline-earth metal.
• the alkaline-earth metals for the sulfonate, salicylate and phenate include calcium, magnesium, barium and so forth, of which calcium is more preferable.
• the alkaline-earth metal salt may be neutral or basic.
• the lubricating oil composition of the present invention for internal combustion engines is required to satisfy diversified requirements, and may be incorporated with one or more additives described below within limits not harmful to the object of the present invention.
• Non-boron-base dispersants include those containing succinimide, succinamide, benzylamine, succinic acid ester, succinic acid ester/amide or the like, of which succinimide-base one is more preferable.
• a succinimide-base dispersant is incorporated at 0.001 to 0.5% by mass based on the whole composition, preferably 0.04 to 0.2% by mass.
• the wear inhibitors useful for the present invention generally include zinc dithiophosphate, a metallic salt of dithiophosphoric acid (Sb, Mo or the like), metallic salt of dithiocarbamic acid (Zn, Sb, Mo or the like), metallic salt of naphthenic acid, metallic salt of fatty acid, boron compound, phosphoric acid ester, phosphorous acid ester, amine salt of phosphoric acid, metallic salt of phosphoric acid, metallic salt of phosphoric acid ester, metallic acid of phosphorous acid ester and so forth. It is incorporated generally at 0.1 to 5% by mass. Of these compounds, zinc dialkyl dithiophosphate is more preferable.
• the wear inhibitor is incorporated at 0.01% by mass or more as phosphorus based on the whole composition, particularly preferably 0.05 to 0.2% by mass.
• the oxidation inhibitors useful for the present invention generally include amine-base ones, e.g., alkylated diphenylamine, phenyl- ⁇ -naphthylamine and alkylated phenyl- ⁇ -naphthylamine; phenol-base ones, e.g., 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol and isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; sulfur-base ones, e.g., dilauryl-3,3'-thiodipropionate; phosphorus-base ones, e.g., phosphite; molybdenum-base ones; and zinc dithiophosphate, of which an amine-base one, phenol-base one and mixture thereof are more preferable.
• the oxidation inhibitor is incorporated generally at 0.04 to 5%
• the viscosity index improvers useful for the present invention generally include polymethacrylate, which may be in the form of dispersion, olefin copolymer (polyisobutylene/propylene or ethylene/propylene copolymer), which may be in the form of dispersion, polyalkylstyrene, hydrogenated styrene/butadiene copolymer, styrene/maleic anhydride ester copolymer and star-shape isoprene, of which an olefin copolymer (polyisobutylene/propylene or ethylene/propylene copolymer) is more preferable.
• polymethacrylate which may be in the form of dispersion
• olefin copolymer polyisobutylene/propylene or ethylene/propylene copolymer
• polyalkylstyrene hydrogenated styrene/butadiene copolymer
• Particularly preferable one is a polyisobutylene/propylene or ethylene/propylene copolymer having a GPC-determined weight-average molecular weight of 100,000 or more as polystyrene.
• a dispersion type olefin copolymer is the one having oxygen or nitrogen in the molecular structure.
• the viscosity index improver is incorporated generally at 0.01 to 30% by mass.
• the pour point depressants useful for the present invention generally include ethylene/vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate and polyalkylstyrene, of which polymethacrylate is particularly preferable.
• the pour point depressant is incorporated generally at 0.01 to 5% by mass.
• the friction-reducing agents useful for the present invention include organomolybdenum-base compound, fatty acid, higher alcohol, fatty acid ester, oil or fat, amine, amide, ether, sulfide ester, phosphoric acid ester, phosphorous acid ester and amine salt of phosphoric acid ester.
• the friction-reducing agent is incorporated generally at 0.05 to 3% by mass.
• the extreme pressure agents useful for the present invention generally include ashless sulfide, sulfided oil or fat, phosphoric acid ester, phosphrous acid ester and amine salt of phosphoric acid ester.
• the extreme pressure agent is incorporated generally at 0.05 to 3% by mass.
• the corrosion inhibitors useful for the present invention include benzotriazole, triazole derivative, benzotriazole derivative, thiazole, thiazole derivative, thiadiazole and thiadiazole derivative.
• the corrosion inhibitor is incorporated at 0.001 to 3% by mass.
• the rust inhibitors useful for the present invention include fatty acid, alkenylsuccinic acid half-ester, fatty acid soap, alkylsulfonate, polyhydric alcohol/fatty acid ester, fatty acid amine, oxidized paraffin and alkylpolyoxyethylene ether.
• the rust inhibitor is incorporated generally at 0.01 to 3% by mass.
• the defoaming agents useful for the present invention include dimethyl polysiloxane and polyacrylate.
• the defoamiong agent is incorporated generally at a very low content, e.g., about 0.002% by mass.
• the lubricant oil composition of the present invention for internal combustion engines may be incorporated with another additive, e.g., colorant, as required.
• a sample incorporated with commercial carbon black at 3% is dropped at 1.0 g/hour onto a sloping panel under conditions of slope angle: 8°, panel temperature: 310°C and test time: 3 hours.
• the sample is charred on the panel to form the deposit, which is treated with petroleum ether to extract the oil remaining in the deposit.
• Amount of the deposit is determined from the panel differential weight before and after the test.
• a sample oil and air are passed into a glass tube (inner diameter: 2 mm) at respective 3 mL/hour and 10 mL/hour, while the tube temperature is kept at 280 or 290°C.
• Color of the lacquer attaching to the tube is compared with the color standard to evaluate the sample according to the following standards, transparent: 10 points and black: 0 points. The higher the point number, the higher performance the sample has.
• the base oil composed of 78.8% of the mineral base oil and 5.1% of the synthetic base oil 1 was incorporated with the DI package (free of a metallic cleaning agent) at 10.1%, viscosity index improver at 5.1%, pour point depressant at 0.1%, defoaming agent at 0.02% and boron-base additive 1 at 0.8% to form Sample (A) of superlow-ash composition, containing the GCD550°C + heavy fraction at 8.0% by volume, boron at 0.02% and sulfated ash content at 0.34%. It had an HTHS viscosity of 3.2 mPa ⁇ s at 150°C, and fell under the SAE viscosity grade of 5W-30.
• Sample (A) was subjected to the hot tube test (carried out at 280°C for 16 hours or 290°C for 16 hours) and panel coking test. The results are given in Table 1. These results indicate that Sample (A) is excellent in cleanability at high temperature and cleanability with lacquer preventing it from depositing on a piston at a low-temperature portion.
• Sample (B) was prepared in the same manner as in Example 1 for preparing Sample (A), except that the boron-base additive 1 was replaced by the boron-base additive 2 which was incorporated at 0.2%. Its composition is given in Table 1. The results of the hot tube test and panel coking test are also given in the table.
• Sample (C) was prepared in the same manner as in Example 1 for preparing Sample (A), except that the synthetic base oil 1 was replaced by the synthetic base oil 2 which was incorporated at 9%. Its composition is given in Table 1. The results of the hot tube test and panel coking test are also given in the table.
• Sample (D) was prepared in the same manner as in Example 1 for preparing Sample (A), except that the synthetic base oil 1 was replaced by the synthetic base oil 2 which was incorporated at 15%. Its composition is given in Table 1. The results of the hot tube test and panel coking test are also given in the table.
• Sample oils (a) to (e) were prepared in respective Comparative Examples 1 to 5 using the base oils and additives to have compositions given in Table 1. Each of these samples lacks at least one of the compositional properties which the present invention requires or has a component out of a content range which the present invention specifies. They were found to fail simultaneously pass the hot tube and panel coking tests, as shown in Table 1, and were notably inferior in performance to the samples of the present invention.
• Sample (a) prepared in Comparative Example 1 although containing the GCD550°C + heavy fraction at 7.6% by volume, contained no boron-base additive. It had the deposited amount sufficiently decreased in the panel coking test, but had the deposited lacquer of black in color in the hot tube test carried out at 290°C, resulting in an evaluation point of 1.0.
• Sample (e) prepared in Comparative Example 5 contained the GCD550°C + heavy fraction at 5.5% by volume, and produced a large amount of the deposit in the panel coking test.
• Sample (d) prepared in Comparative Example 4 although containing GCD550°C + heavy fraction at a content reaching 8.0% by volume, showed a very low evaluation point in the hot tube test carried out at 290°C because of absence of boron (which should be contained at least at 0.02% by mass):
• the sample oil simultaneously satisfying the GCD550°C + heavy fraction content of 6% by volume or more, sulfated ash content of 0.6% by mass or less and boron content of at least 0.02% by mass as the compositional properties can have a high evaluation point in the hot tube tests carried out at 280 and 290°C, and greatly suppressed formation of the deposit in the panel coking test. As such, it exhibits high cleanability in spite of its superlow ash composition and brings very notable effects.

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• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)

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