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
  • C10M137/02—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing phosphorus having no phosphorus-to-carbon bond
  • C10M137/04—Phosphate esters
  • C10M137/10—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
  • 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
  • C10M2207/02—Hydroxy compounds
  • C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/028—Overbased salts thereof
• • 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
  • C10M2215/24—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
  • C10M2219/044—Sulfonic acids, Derivatives thereof, e.g. neutral 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
  • 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
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/04—Molecular weight; Molecular weight distribution
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/12—Inhibition of corrosion, e.g. anti-rust agents or anti-corrosives
• • 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
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/25—Internal-combustion engines

Definitions

• the present invention is related, in part, to a lubricating oil composition. More particularly, the present invention relates to a low phosphorus lubricating oil composition employing a mixture of zinc dithiophosphates and wherein the lubricating oil composition has less than about 0.06 wt % total phosphorus content based on the total weight of the lubricating oil composition.
• the low phosphorus lubricating oil composition of the present invention is effective in lead corrosion control when used as a lubricating oil composition in internal combustion engines.
• Catalytic converters are now universally employed with gasoline powered vehicles and the efficiency of these converters is directly related to the ability of the catalyst to effect conversion of unburnt or partially burnt hydrocarbons generated during combustion to carbon dioxide and water.
• One problem arising with the use of such converters is poisoning of the catalyst resulting in reduced catalyst efficiency. Since catalytic converters are intended for extended use, catalyst poisoning results in higher levels of atmospheric discharges of pollutants from internal combustion engines over prolonged periods of time.
• standards for fuels have included the use of unleaded gasoline in order to avoid lead poisoning of the catalyst as well as lead discharge into the environment. See, for example, Buckley, Ill, " Long Chain Aliphatic Hydrocarbyl Amine Additives Having an Oxyalkylene Hydroxy Connecting Group", U.S. Patent No. 4,975,096, issued December 4, 1990 .
• phosphorus-containing additives such as zinc dithiophosphate wear inhibitors used lubricant compositions employed to lubricate internal combustion engines.
• phosphorus-containing additives reach the catalytic converter as a result of, for example, exhaust gas recirculation and/or oil blow-by processes as well as other methods known in the art. See, for example, Beck, et al. "Impact of Oil-Derived Catalyst Poisons on FTP Performance of LEV Catalyst Systems"; SAE Technical Paper 972842 (1997 ) and Darr et al.
• One well known class of antiwear additives are metal alkylphosphates, especially zinc dialkyl dithiophosphates, are generally employed in lubricating oils at phosphorous levels above 0.1 weight percent when used for wear control. At lower levels, it is not found to be an effective antiwear additive. For instance, as exemplified in U.S. Patent No.
• Zinc dithiophosphates have either dialkyl or diaryl groups. Zinc dialkyl dithiophosphates are further subdivided into primary alkyl and secondary alkyl zinc dithiophosphates. Pentan-1-ol and 3-methylbutan-2-ol are illustrative of the primary and secondary alcohols used to prepare primary and secondary zinc dithiophosphates Different zinc dithiophosphate chemical types perform differently (See below).
• EP 1 403 359 discloses a low ash lubricating oic composition inhibiting lead corrosion.
• the present invention is related, in part, to a lubricating oil composition. More particularly, the present invention relates to a low phosphorus lubricating oil composition employing a mixture of zinc dithiophosphates in a certain ratio and wherein the lubricating oil composition has less than about 0.06 wt % total phosphorus content, based on the total weight of the lubricating oil composition.
• the low phosphorus lubricating oil composition of the present invention is effective in lead corrosion control when used as a lubricating oil composition in internal combustion engines.
• the present invention is related to a lubricating oil composition
• a lubricating oil composition comprising a major amount of base oil of lubricating viscosity and a minor amount of at least 0.1 wt% to 1.5 wt% of a mixture of a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate wherein the respective ratio, based on the phosphorus content, of the zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is from about 2:1 to about 1:2 and the ratio of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 6:1 to about 1:1 and wherein the total phosphorus content of the lubricating oil composition is less than about 0.06 wt %, based on the total weight of the lubricating oil composition.
• the minor amount of the mixture of a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate employed in the lubricating oil composition of the present invention is from about 0.1 wt % to about 1.5 wt %, preferably from about 0.3 wt % to about 1.2 wt % and more preferably about 0.5 wt % to about 1.0 wt %, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.05 wt % to about 1.2 wt % of a zinc primary dialkyl dithiophosphate, from about 0.05 wt % to about 1.2 wt % of a zinc secondary dialkyl dithiophosphate and from about 0.02 wt % to about 0.7 wt % of a zinc diaryl dithiophosphate, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.1 wt % to about 0.7 wt % of a zinc primary dialkyl dithiophosphate, from about 0.1 wt % to about 0.7 wt % of a zinc secondary dialkyl dithiophosphate and from about 0.05 wt % to about 0.5 wt % of a zinc diaryl dithiophosphate, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.2 wt % to about 0.5 wt % of a zinc primary dialkyl dithiophosphate, from about 0.2 wt % to about 0.5 wt % of a zinc secondary dialkyl dithiophosphate and from about 0.1 wt % to about 0.3 wt % of a zinc diaryl dithiophosphate, based on the total weight of the lubricating oil composition.
• the primary alkyl group of the zinc primary dialkyl dithiophosphate has from about C 1 to about C 13 carbon atoms, preferably from about C 3 to about C 10 carbon atoms and more preferably, from about C 6 to about C 8 carbon atoms.
• the secondary alkyl group of the zinc secondary dialkyl dithiophosphate has from about C 3 to about C 13 carbon atoms, preferably from about C 3 to about C 8 carbon atoms and more preferably, from about C 3 to about C 6 carbon atoms.
• the aryl group of the zinc diaryl dithiophosphate has from about C 6 to about C 30 carbon atoms preferably from about C 6 to about C 24 carbon atoms and more preferably, from about C 6 to about C20 carbon atoms.
• the respective ratio, based on the phosphorus content, of zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is from about 3:2 to about 2:3. More preferably, the ratio is about 1:1.
• the respective ratio, based on the phosphorus content, of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 4:1 to about 1:1. More preferably, the ratio is bout 2:1.
• the respective ratio, based on the phosphorus content, of the mixture of zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is 1:1:1.
• the total phosphorus content in the lubricating oil composition of the present invention is preferably less than about 0.05 wt %, more preferably, based on the total weight of the lubricating oil composition.
• the sulfur content in the lubricating oil composition of the present invention is less than about 0.5 wt % and, preferably, less than about 0.2 wt %, based on the total weight of the lubricating oil composition and the total sulfated ash contest in the lubricating oil composition of the present invention is less than about 1.2 wt %, preferably, less than about 1.0 wt %, and more preferably less than about 0.8 wt %, based on the total weight of the lubricating oil composition.
• the present invention further relates to a method for improving lead corrosion.
• the method involves operating an internal combustion engine with a lubricating oil composition comprising a major amount of base oil of lubricating viscosity and a minor amount of a mixture of a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate wherein the respective ratio, based on the phosphorus content, of the zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is from about 2:1 to about 1:2 and the ratio of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 6:1 to about 1:1 and wherein the total phosphorus content of the lubricating oil composition is less than about 0.06 wt %, based on the total weight of the lubricating oil composition.
• the present invention provides a low phosphorus lubricating oil composition containing a mixture of zinc dithiophosphates in a certain ratio surprisingly yields improved lead corrosion.
• the mixture of zinc dithiophospates contains a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate.
• the synergistic combination of mixed zinc dithiophosphates wherein the respective ratio, based on the phosphorus content, of the zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is from about 2:1 to about 1:2 and the ratio of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 6:1 to about 1:1 when used in a lubricating oil composition having a total phosphorus content less than about 0.06 wt %, based on the total weight of the lubricating oil composition, greatly reduces lead corrosion when used to lubricate internal combustion engines.
• the present invention is related, in part, to a lubricating oil composition. More particularly, the present invention relates to a low phosphorus lubricating oil composition employing a mixture of zinc dithiophosphates containing a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate wherein the respective ratio, based on the phosphorus content, of the zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is from about 2:1 to about 1:2 and the ratio of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 6:1 to about 1:1 and wherein the lubricating oil composition has less than about 0.06 wt % total phosphorus content, based on the total weight of the lubricating oil composition.
• the low phosphorus lubricating oil composition of the present invention is effective in lead corrosion control when used as a lub
• alkyl refers to both straight- and branched-chain alkyl groups.
• aryl refers to a substituted or unsubstituted aromatic group, such as the phenyl, tolyl, xylyl, ethylphenyl and cumenyl groups.
• low phosphorus refers to the phosphorus content of the lubricating oil composition of the present invention.
• the phosphorus content is in the range of about 0.005 weight percent to about 0.06 weight percent based on the total weight of the lubricating oil composition.
• total phosphorus refers to the total amount of phosphorus in the lubricant composition regardless of whether such phosphorus is present as part of an oil-soluble, phosphorus-containing, anti-wear compound or in the form of a contaminant in the lubricant composition such as residual phosphorus remaining due to the presence of P 2 S 5 used to prepare metal dihydrocarbyl dithiophosphates. In either event, the amount of phosphorus permitted in the lubricant composition is independent of source. Preferably, however, the phosphorus is part of a lubricant additive.
• the lubricating oil composition of the present invention will employ, in part, a mixture of zinc dithiophosphates.
• the zinc dithiophosphates are independently characterized by formula I: wherein each R is independently a group containing from about 1 to about 30 carbon atoms.
• the R groups in the dithiophosphate can independently be about C 1 to about C 13 primary alkyl, about C 3 to about C 13 secondary alkyl and about C 6 to about C 30 aryl group.
• the R groups in the dithiophosphate can independently be about C 3 to about C 10 primary alkyl, about C 3 to about C 8 secondary alkyl, and about C 6 to about C 24 aryl group.
• the R groups in the dithiophosphate can independently be about C 6 to about C 8 primary alkyl, about C 3 to about C 6 secondary alkyl, and about C 6 to about C 20 aryl group.
• the R groups may be a substantially hydrocarbon group.
• substantially hydrocarbon is meant hydrocarbons that contain substituent groups such as ether, ester, nitro, or halogen which do not materially affect the hydrocarbon character of the group.
• the R group of the zinc dithiophosphate may be derived, for example, from a primary alcohol such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, octadecanol, propenol, butenol, 2-ethylhexanol; a secondary alcohol such as isopropyl alcohol, secondary butyl alcohol, isobutanol, 3-methylbutan-2-ol, 2-pentanol, 4-methyl-2-pentanol, 2-hexanol, 3-hexanol, amyl alcohol; an aryl alcohol such as phenol, substituted phenol (particularly alkylphenol such as butylphenol, octylphenol, nonylphenol, dodecylphenol), disubstituted phenol.
• a primary alcohol such as
• the R group will be independently a primary alkyl, a secondary alkyl or an aryl group.
• the mixture of a zinc primary dialkyl dithiophosphate, a zinc secondary dialkyl dithiophosphate and a zinc diaryl dithiophosphate will be in a respective ratio, based on the phosphorus content, in the Lubricating oil composition of the present invention.
• the ratio of zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate will be from about 2:1 to about 1:2 and the ratio of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is from about 6:1 to about 1:1.
• the respective patio, based on the phosphorus content, of zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate is a range from about 3:2 to about 2:3, more preferably about 1:1.
• the respective ratio, based on the phosphorus content, of the mixture of zinc primary dialkyl dithiophosphate and zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is a range from about 4:1 to about 1:1, more preferably about 2:1.
• the respective ratio, based on the phosphorus content, of the mixture of zinc primary dialkyl dithiophosphate to zinc secondary dialkyl dithiophosphate to zinc diaryl dithiophosphate is 1:1:1.
• zinc dithiophosphates useful in the present invention are available commercially. However, zinc dithiophosphates are widely known in the art and a skilled artisan can readily synthesize such compounds for the purpose of the present invention.
• zinc dithiophosphates can be made by initial reaction of phosphorous pentasulfide and an alcohol or phenol or mixtures of alcohols and/or phenols such as those illustrated above for the R group. The reaction involves four moles of the alcohol or phenol per mole of phosphorous pentasulfide, and may be carried out within the temperature range from about 50°C to about 200°C.
• the preparation of O,O-di-n-hexyl phosphorodithioic acid involves the reaction of phosphorous pentasulfide, with four moles of n-hexyl alcohol at about 100°C for about two hours. Hydrogen sulfide is liberated and the residue is phosphorodithioic acid.
• the preparation of the metal salt of this acid may be effected by reaction with either zinc oxide or zinc hydroxide to yield the zinc dithiophosphate. Simply mixing and heating these two reactants is sufficient to cause the reaction to take place and the resulting product is sufficiently pure for the purposes of the present invention.
• Patents describing the synthesis of such zinc dithiophosphates include U.S. Patent Nos. 2,680,123 ; 3,000,822 ; 3,151,075 ; 3,385,791 ; 4,377,527 ; 4,495,075 arid 4,778,906 . Each of these patents is incorporated herein by reference in their entirety.
• the mixture of zinc dithiophosphates of the present invention is typically added to a base oil in sufficient amounts to provide lead corrosion control in internal combustion engines.
• the lubricating oil composition of the present invention will contain a major amount of base oil of fabricating viscosity and a minor amount of the mixture of zinc dithiophosphates of the present invention.
• Base oil as used herein is defined as a base stock or blend of base stocks which is a lubricant component that is produced by each manufacturer to the same specifications (independent of feed source or manufacturer's location); that meets the same manufacturer's specification; and that is identified by a unique formula, product identification number, or both.
• Base stocks may be manufactured using a variety of different processes including but not limited to distillation, solvent refining, hydrogen processing, oligomerization, esterification, and redefining.
• the base oil of this invention may be any natural or synthetic lubricating base oil fraction particularly those having a kinematic viscosity at 100° Centigrade, (°C) and about 4 centistokes (cSt) to about 20 cSt.
• Hydrocarbon synthetic oils may include, for example, oils prepared from the polymerization of ethylene, polyalphaolefin or PAO, or from hydrocarbon synthesis procedures using carbon monoxide and hydrogen gasses such as in a Fisher-Tropsch process.
• a preferred base oil is one that comprises little, if any, heavy fraction; e.g., little, if any, lube oil fraction of viscosity about 20 cSt or higher at about 100°C Oils used as the base oil will be selected or blended depending on the desired end use and the additives in the finished oil to give the desired grade of engine oil, e.g.
• a lubricating oil composition having an SAE Viscosity Grade of 0W, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30, or 15W-40.
• the base oil may be derived from natural lubricating oils, synthetic lubricating oils or mixtures thereof.
• Suitable base oil includes base stocks obtained by isomerization of synthetic wax and stack wax, as well as hydrocrackate base stocks produced by hydrocracking (rather than solvent extracting) the aromatic and polar components of the crude.
• Suitable base oils include those in all API categorizes I, II, III, IV and V as defined in API Publication 1509, 14th Edition, Addendum I, December 1998. Saturates levels and viscosity indices, for Group I, II and 111 base oils are listed in Table I.
• Group IV base oils are polyalphaolefins (PAO).
• Group V base oils include all other base oils not included in Group I, II, III, or IV.
• Group III base oils are preferred. TABLE I. SATURATES, SULFUR AND VISCOSITY INDEX OF GROUP I, II, III, IV AND V BASE STOCKS Group Saturates (As determined by ASTM D2007) Viscosity Index Sulfur (As determined by ASTM D2270) (As determined by ASTM D4294, ASTM D4297 or ASTM D3120) I. Less than 90 % saturates and/or Greater than to 0.03 % sulfur Greater than or equal to 80 and less than 120 II.
• Natural lubricating oils may include animal oils, vegetable oils (e.g., rapeseed oils, castor oils and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale.
• vegetable oils e.g., rapeseed oils, castor oils and lard oil
• petroleum oils e.g., mineral oils, and oils derived from coal or shale.
• Synthetic oils may include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and inter-polymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogues and homologues thereof, and the like.
• Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification, etherification, etc.
• Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids with a variety of alcohols.
• Esters useful as synthetic oils also include those made from about C 5 to about C 12 monocarboxylic acids and polyols and polyol ethers Tri-alkyl phosphate ester oils such as those exemplified by tri-n-butyl phosphate and tri-iso-butyl phosphate are also suitable for use as base oils.
• Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxysiloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils.
• Other synthetic lubricating oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.
• the base oil may be derived from unrefined, refined, rerefined oils; or mixtures thereof.
• Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sand bitumen) without further purification or treatment: Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which may then be used without further treatment.
• Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties.
• Suitable purification techniques include distillation, hydrocracking, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art
• Rerefined oils are obtained by treating used oils in processes similar to those used to obtain the refined oils. These rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.
• Base oil derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforesaid natural and/or synthetic base oil.
• Such wax isomerate oil is produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst.
• a major amount of base oil as defined herein comprises about 40 wt % or more.
• Preferred amount of base oil comprise about 40 wt % to about 97 wt %, preferably greater than about 50 wt % to about 97 wt %, more preferably about 60 wt % to about 97 wt % and most preferably about 80 wt % to about 95 wt % of the lubricating oil composition. (when weight percent is used herein, it is referring to weight percent of the lubricating oil unless otherwise specified.)
• the amount of the mixture of zinc dithiophosphates employed in the lubricating oil composition of the present invention will be in a minor amount compared to the base oil of lubricating viscosity. Generally, it will be in an amount from about 0.1 wt % to about 1.5 wt%, preferably from about 03.3 wt % to about 1.2 wt % and more preferably from about 0.5 wt % to about 1.0 wt %, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.05 wt % to about 1.2 wt %, preferably from about 0.1 wt % to about 0.7 wt %, and more preferably from about 0.2 wt % to about 0.5 wt % of a zinc primary dialkyl dithiophosphate, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.05 wt % to about 1.2 wt %, preferably from about 0.1 wt % to about 0.7 wt %, and more preferably from about 0.2 wt % to about 0.5 wt % of a zinc secondary dialkyl dithiophosphate, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will contain from about 0.02 wt % to about 0.7 wt %, preferably from about 0.05 wt % to about 0.5 wt %, and more preferably from about 0.1 wt % to about 0.3 wt % of a zinc primary diaryl dithiophosphate, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will have a phosphorus content preferably less than about 0.05 wt %, based on the total weight of the lubricating oil composition.
• the lubricating oil composition of the present invention will further have a sulfur content less than about 0.5 wt % and, preferably less than about 0 2 wt %, based on the total weight of the lubricating oil composition and the total sulfated ash content in the lubricating oil composition of the present invention is less than about 1.2 wt %, preferably, less than about 1.0 wt %, and more preferably less than about 0.8 wt %, based on the total weight of the lubricating oil composition.
• additive components are examples of components that can be favorably employed in combination with the lubricating additive of the present invention. These examples of additives are provided to illustrate the present invention, but they are not intended to limit it.
• the low phosphorus lubricating oil composition of the present invention was prepared by blending a 0.78 wt % mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate (0.24 wt%, primary), zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate (0.15 wt %, secondary) and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate (0.39 wt %, aryl) with a Group II base oil of lubricating viscosity.
• the ratio of zinc bis(O,O'-di(2-ethyl-1-hexyl) dithiophosphate to zinc bis(O,O'-di-(2-butyl/4-methy)-2-pentyl) dithiophosphate was about 1:1, based on the phosphorus content.
• the ratio of the mixture of zinc bis(O,O'-di(2-ethyl-1-hexyl) dithiophosphate and zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate to zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate was about 2:1, based on the phosphorus content.
• the resulting ratio of the three-way mixture of zinc bis(O,O'-di(2-ethyl-1-hexyl) dithiophosphate to zinc bis(O,O'-di'-(2-butyl/4-methyl-2-pentyl) dithiophosphate to zinc bis(O,O'-di(dodecylphenyl) dithiophosphate was 1:1:1, based on the phosphorus content.
• the wt % of phosphorus in the prepared lubricating oil composition was less than about 0.06 wt % based on the total weight of the lubricating oil composition.
• the sulfur content and sulfated ash content were 0.2 wt% and 0.8 wt%, respectively, based on the total weight of the lubricating oil composition.
• the wt % balance of the lubricating oil composition containing a 1200 molecular weight (MW) isobutylene bis-succinimide dispersant, a 2300 MW isobutylene bis-succinimide dispersant, a neutral sulfonate detergent, an overbased calcium phenate, a molybdenum oxidation inhibitor, diphenylamine oxidation inhibitor, a phenolic oxidation inhibitor, anti-foam agent, pour point depressant and a viscosity index improver to complete the 100 wt % lubricating oil composition.
• MW molecular weight
• 2300 isobutylene bis-succinimide dispersant
• a neutral sulfonate detergent an overbased calcium phenate
• Comparative Example A was prepared according to Example 1 except only about 1.16 wt % aryl zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate was added, instead of the mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate, zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate.
• Comparative Example B was prepared according to Example 1 except only about 0.46 wt % zinc bis(O,O'-di-(2-butyl-4-methyl-2-pentyl) dithiophosphate was added, instead of the mixture of zinc-bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate, zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate.
• Comparative Example C was prepared according to Example 1 except only about 0.71 wt % zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate was added, instead of the mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate, zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate.
• Comparative Example D was prepared according to Example 1 except about 0.81 wt % of a mixture of zinc bis (O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis (O,O'-di-(dodecylphenyl) dithiophosphate in about a 1:1 ratio were added, instead of the mixture of zinc bis(O,O-di-(2-ethyl-1-hexyl) dithiophosphate zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis (O,O'-di-(dodecylphenyl) dithiophosphate.
• Comparative Example E was prepared according to Example 1 except about 0.94 wt % of a mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate in about a 1:1 ratio were added, instead of the mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate, zinc bis (O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate.
• Comparative Example F was prepared according to Example 1 except about 0.59 wt% of a mixture of zinc bis (O,O'-di-(2-ethyl-1-hexyl) dithiophosphate and zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate in about a 1:1 ratio were added, instead of the mixture of zinc bis(O,O'-di-(2-ethyl-1-hexyl) dithiophosphate, zinc bis(O,O'-di-(2-butyl/4-methyl-2-pentyl) dithiophosphate and zinc bis(O,O'-di-(dodecylphenyl) dithiophosphate.
• Example 1 and Comparative Example A-F were tested for lead corrosion using the High Temperature Corrosion Bench Test (HTCBT)(ASTM D6594) which is an industry standard bench test to measure corrosion performance of a motor oil. Briefly, four metal specimens of copper, lead, tin, and phosphor bronze are immersed in a measured amount of engine oil. The oil, at an elevated temperature, is blown with air for a period of time. When the test is completed, the lead specimen and the stressed oil are examined to detect corrosion and corrosion products, respectively. A reference oil is tested with:each group of tests to verify test acceptability.
• HTCBT High Temperature Corrosion Bench Test
• Example 1 containing a mixture of zinc primary dialkyl dithiophosphate, zinc secondary dialkyl dithiophosphate and zinc diaryl dithiophosphate in a 1:1:1 ratio, and wherein the phosphorus content of the lubricating oil composition is less than 0.06 wt%, provides excellent lead corrosion performance when compared to the comparative examples not having a mixture of all three dithiophosphates. The amount of lead corrosion is significantly reduced by the lubricating oil composition of the present invention.

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