MARINE DIESEL ENGINE LUBRICATING OIL COMPOSITION

FIELD OF INVENTION

[0001] The present invention relates to lubricating oil compositions for a marine application, particularly for use as marine diesel lubricants for both cross-head engines and trunk piston engines. The lubricating oil compositions exhibit improved oxidative stability, viscosity increase control, detergency performance and water tolerance.

BACKGROUND OF THE INVENTION

Diesel engines are employed as internal combustion engines for the operation of marine vessels and are generally classified as slow-speed, medium-speed, or high-speed engines.

[0002] Slow-speed diesel engines are unique in size and method of operation. The output of these engines can reach as high as 100,000 brake horsepower with engine revolutions of 60 to about 200 revolutions per minute. They are typically of the crosshead design and operate on the two-stroke cycle. Due to the design and construction of these engines, in which the crosshead separates the firing cylinder from the crankcase and a stuffing box completes the seal, the cylinders and crankcases are lubricated separately by a marine cylinder oil and marine system oil, respectively.

[0003] The primary function of a marine cylinder lubricant is to provide a strong oil film between the cylinder liner and the piston rings. A marine cylinder lubricant is consumed during operation of the engine and therefore lubricates the cylinders on a total loss basis. Although fresh lubricant oil is supplemented periodically to compensate for the consumed portion, the exposure to thermal and other stresses, such as the use of residual fuels, cause increased amounts of sulfur oxide compounds and combustion residues which increase and remain in the lubricating oil . Therefore, after the engine is operated continuously for a long period of time, the lubricating oil suffers from deterioration and viscosity increase due to deposit contamination and oxidation of the oil.

[0004] A marine system oil lubricates the crankcase of a crosshead marine diesel engine and may cool parts of the engine, especially the undercrown of the pistons. In some engines, the system oil also performs the function of lubricating gears and fuel pumps. Properties that are typically important to system oils are oxidative stability, viscosity increase control and detergency of the oil. [0005] Medium-speed trunk piston engines, on the other hand, typically operate in the range of about 250 to about 1 100 rpm and typically operate on the four-stroke cycle. These engines are typically of the trunk piston design. In contrast to the slow-speed engines, the connecting rod is attached directly to the piston. Therefore, a single lubricant is used for both crankcase and cylinder lubrication in trunk piston engines. Therefore, these oils are required to have the ability to form a protective layer between moving surfaces, neutralize acids and keep contaminants suspended in the oil, properties which are adversely affected by oxidation of the oil resulting in viscosity increase, loss of neutralization capacity and loss of detergency.

[0006] There is a need in the art for lubricating oil compositions that exhibit improved oxidative stability, viscosity increase control, detergency performance and water tolerance in a variety of marine applications. The use of overbased metal-containing detergents such as alkaline earth metal sulfonate, phenates and salicylates are known in the art as additives used to neutralize sulfur oxide produced by combustion of the fuel and disperse combustion deposits such as sludge.

[0007] Medium to long chain alkyl aromatics are used to make high volume additives and surfactants. Examples of such compounds are alkyl aromatic phenates used in lubricant additives. Phenates are widely used for their detergency and antioxidant properties.

[0008] Low molecular weight alkylphenols such as tetrapropenyl phenol (TPP) have been used as a raw material by producers of sulfurized, overbased phenates. When sulfurized, overbased phenates are made generally there is unreacted alkylphenol in the final reaction product. A recent reproductive toxicity study in rats sponsored by the Petroleum Additives Panel of the American Chemistry Counsel shows that in high concentrations unreacted TPP may cause adverse effects in males and female reproductive organs.

[0009] To reduce any potential health risks to customers and avoid potential

regulatory issues there is a need to reduce the amount of unreacted low molecular weight alkyl hydroxyaromatic compounds in overbased, sulfurized salts of alkylated hydroxyaromatic compounds. Linear olefins are a possible alternative to avoid reprotoxicity in the derived alkylphenols; however, the linearity of the olefin can lead to poor low temperature properties in lubricating oils containing the derived sulfurized, overbased phenates.

[0010] The present invention is directed to achieving improvements in performance of marine diesel lubricants by employing a specific combination of overbased detergents at optimum ratios.

SUMMARY OF THE INVENTION

[0011] A first aspect of the invention is a marine diesel lubricant composition having a TBN of about 5 to about 120 comprising:

(a) a major amount of a base oil of lubricating viscosity;

(b) a first detergent that is an alkaline earth metal salt of an overbased Cio-40 alkylarylsulfonate detergent; and

(c) a second detergent that is an alkaline earth metal salt of an overbased isomerized C 10-40 normal alpha olefin based sulfurized phenate detergent;

wherein the weight ratio of the first detergent to the second detergent ranges from 1 :9 to 9: 1.

[0012] A second aspect of the invention is a marine diesel lubricating oil additive concentrate containing a compatible organic diluent, a first detergent that is an overbased alkaline earth metal C 10-40 alkylaryl sulfonate detergent; and a second detergent that is an overbased alkaline earth metal isomerized Cio-40 normal alpha olefin based sulfurized phenate detergent; wherein the weight ratio of the first detergent to the second detergent ranges from 1 :9 to 9: 1.

[0013] A third aspect of the invention relates to a method of producing the marine diesel lubricating oil composition of the invention by blending together a mixture of the components of the lubricating oil composition. The resulting lubricating oil compositions exhibit improved oxidative stability, viscosity increase control, detergency performance and water tolerance.

[0014] A fourth aspect of the invention is a method of operating a marine diesel engine comprising lubricating the engine with a lubricating oil composition having a TBN of about 5 to about 120 comprising:

(a) a major amount of a base oil of lubricating viscosity;

(b) a first detergent that is an alkaline earth metal salt of an overbased Cio-40 alkylarylsulfonate detergent; and

(c) a second detergent that is an alkaline earth metal salt of an overbased isomerized C 10-40 normal alpha olefin based sulfurized phenate detergent;

wherein the weight ratio of the first detergent to the second detergent ranges from 1 :9 to 9: 1.

[0015] A fifth aspect of the invention is a method of lubricating the cylinder of a marine diesel engine comprising lubricating the cylinder with a lubricating oil composition having a TBN of about 5 to about 120 comprising:

(a) a major amount of a base oil of lubricating viscosity;

(b) a first detergent that is an alkaline earth metal salt of an overbased Cio-40 alkylarylsulfonate detergent; and

(c) a second detergent that is an alkaline earth metal salt of an overbased isomerized C 10-40 normal alpha olefin based sulfurized phenate detergent;

wherein the weight ratio of the first detergent to the second detergent ranges from 1 :9 to 9: 1.

[0016] In one embodiment, the alkaline earth metal in the overbased alkaline earth metal alkylaryl sulfonate detergent and the overbased alkaline earth metal isomerized normal alpha olefin based sulfurized phenate detergent is calcium.

[0017] In one embodiment, the alkyl substituent of the overbased isomerized normal alpha olefin based phenate detergent is made by isomerizing a mixture of C14-C24 normal alpha olefins.

[0018] In one embodiment, the weight ratio of the overbased alkaline earth metal alkylaryl sulfonate detergent to the overbased alkaline earth metal isomerized normal alpha olefin based sulfurized phenate detergent ranges from 1 :9 to 9: 1.

DETAILED DESCRIPTION OF THE INVENTION

[0019] In its broadest aspect, the present invention relates to a lubricating oil composition for a marine application.

[0020] Definitions:

[0021] To facilitate the understanding of the subject matter disclosed herein, a number of terms, abbreviations or other shorthand as used herein are defined below. Any term, abbreviation or shorthand not defined is understood to have the ordinary meaning used by a skilled artisan contemporaneous with the submission of this application.

[0022] The term "major amount" as used herein refers to a concentration within the lubricating oil composition of at least about 40 wt. %. In one embodiment, the term "major amount" refers to a concentration within the lubricating oil composition of at least about 50 wt. %. In another embodiment, the term "major amount" refers to a concentration within the lubricating oil composition of at least about 60 wt. %. In yet another embodiment, the term

"major amount" refers to a concentration within the lubricating oil composition of at least about 70 wt. %. In still another embodiment, the term "major amount" refers to a concentration within the lubricating oil composition of at least about 80 wt. %. In another embodiment, the term "major amount" refers to a concentration within the lubricating oil composition of or at least about 90 wt. %.

[0023] The term "alkaline earth metal" refers to calcium, barium, magnesium, and strontium.

[0024] The term "alkali metal" refers to lithium, sodium, potassium, rubidium, and cesium.

[0025] The term "olefins" refers to a class of unsaturated aliphatic hydrocarbons having one or more carbon-carbon double bonds. Those containing one double bond are called mono-alkenes, and those with two double bonds are called dienes, alkyldienes, or diolefins. Alpha olefins are particularly reactive because the double bond is between the first and second carbon of the hydrocarbon chain. Examples of alpha olefins include 1-octene and 1- octadecene, which are used as the starting point for medium-biodegradable surfactants.

Linear and branched olefins are also included in the definition of olefins.

[0026] The term "normal olefins," which include normal alpha olefins, refers to olefins which are straight chain, non-branched hydrocarbons with at least one carbon-carbon double bond present in the chain.

[0027] The term "isomerized olefins" refers to olefins obtained by isomerizing olefins.

Generally isomerized olefins have double bonds in different positions than the starting olefins from which they are derived, and may also have different characteristics.

[0028] The term "lime" refers to calcium hydroxide, also known as slaked lime or hydrated lime.

[0029] The term "phenate" means a salt of a phenol.

[0030] The term "overbased" is used to describe a metal detergent in which the ratio of the number of equivalents of the metal moiety to the number of equivalents of the acid moiety is greater than one. The phrase "highly overbased" means a TBN of about 250 or more.

[0031] The term "overbased calcium salt of a detergent" means an overbased detergent in which the metal cations of the metal salt are essentially calcium cations. Small amounts of other cations may be present in the metal salt, but typically at least 80, more typically at least 90, for example at least 95, mole %, of the cations in the metal salt, are calcium ions.

[0032] The term "Total Base Number" or "TBN" or "BN" refers to the equivalent number of milligrams of KOH needed to neutralize 1 gram of a product. Therefore, a high TBN reflects strongly overbased products and, as a result, a higher base reserve for neutralizing acids. The TBN of a product can be determined by ASTM Standard No. D2896 or equivalent procedure.

[0033] The phrase "charge molar ratio" or "CMR," when referring to a phenate detergent, is the ratio of the moles of alkylphenol detergent/moles of lime used during the over-basing process.

[0034] All concentrations of materials and ratios disclosed in this application, unless otherwise specified, are on an "actives" basis; that is, additive material that is not diluent or solvent.

[0035] The Base Oil of Lubricating Viscosity:

[0036] The base oil of lubricating viscosity for use in the lubricating oil compositions of this invention, also referred to as a base oil, is typically present in a major amount, e.g., an amount of greater than 50 wt. %, preferably greater than about 70 wt. %, more preferably from about 80 to about 99.5 wt. % and most preferably from about 80 to about 98 wt. %, based on the total weight of the composition. The expression "base oil" as used herein shall be understood to mean a base stock or blend of base stocks which is a lubricant component produced by a single manufacturer to the same specifications (independent of feed source or ma ufacturer's location) that meets the same ma ufacturer's specification and is identified by a unique formula, product identification number, or both. The base oil for use herein can be any presently known or later-discovered oil of lubricating viscosity used in formulating lubricating oil compositions for marine diesel engines.

[0037] In one embodiment, the lubricating base oil has a kinematic viscosity of 22 to 300 ninrV's at 40° C, preferably 22 to 140 mnfVs at 40° C, and kinematic viscosity of 2 to 40 mm /s at 100 ° C, preferably 3 to 15 nsitf/s at 100° C.

[0038] Base stocks may be manufactured using a variety of different processes including, but not limited to, distillation, solvent refining, hydrogen processing, oligomerization, esterification, and rerefining. Rerefined stock shall be substantially free from materials introduced through manufacturing, contamination, or previous use. The base oil of the lubricating oil compositions of this invention may be any natural or synthetic lubricating base oil.

[0039] The base oil may be deri ved from natural lubricating oils, synthetic lubricating oils, or mixtures thereof. Suitable base oil includes base stocks obtained by isomerization of synthetic wax and slack wax, as well as hvdrocracked base stocks produced by hydrocrackmg (rather than solvent extracting) the aromatic and polar components of the crude. Suitable base oils include those in all API categories I, II, III, IV, and V as defined in API Publication 1509, 14th Edition, Addendum I, December 1998. Group IV base oils are polyalphaolefms (PAO). Group V base oils include all other base oils not included in Group I, II, ITT, or IV. In one embodiment, the base oil of lubricating viscosity is a Group Ϊ and/or a Group II base oil.

|0040] Useful natural oils include mineral lubricating oiis such as, for example, liquid petroleum oils; solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic, or mixed paraffinic-naphthenic types: oils derived from coal or shale: animal oils; and vegetable oils (e.g., rapeseed oils, castor oils and lard oil).

[0041] Useful synthetic lubricating oils include, but are not limited to, hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, e.g. , polybutylenes, polypropyienes, propylene-isobutylene copolymers, chlorinated

polybutylenes, poly(l -hexenes), poly(l-octenes), poly(l -decenes), and mixtures thereof, alkyibenzenes such as dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, and di(2- ethyihexyi)-benzenes, poiyphenyis such as biphenyls, terphenyls, and alkylated polyphenols, alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivative, analogs and horaologs thereof. Such synthetic lubricating oiis include, but are not limited to, oiis made by polymerizing olefins of less than 5 carbon atoms such as ethylene, propylene, butylenes, isobutene, pentene, and mixtures thereof. Methods of preparing such polymer oils are well known to those skilled in the art.

[0042] Suitable hydrocarbon synthetic oils include, but are not limited to, oiis prepared from the polymerization of ethylene or from the polymerization of 1 -olefins to provide polymers such as polyalphaolefin or PAO oils, or from hydrocarbon synthesis procedures using carbon monoxide and hydrogen gases such as in a Fischer-Tropsch process.

[0043] Additional useful synthetic hydrocarbon oils include liquid polymers of alpha olefins having the proper viscosity. Especially useful synthetic hydrocarbon oils are the hydrogenated liquid oligomers of C ₆ to Ct ₂ alpha olefins such as, for example, 1-decene trimer.

[0044] Another class of useful synthetic lubricating oils include, but are not limited to, aiky iene oxide polymers, i.e., homopoivmers, interpolymers, and derivatives thereof where the terminal hydroxy! groups have been modified by, for example, esterifi cation or etherification. These oils are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and phenyl ethers of these polyoxyalkylene polymers (e.g., methyl poly propylene glycol ether having an average molecular weight of 1,000, diphenyl ether of polyethylene gly col having a molecular weight of 500 to 1000, and diethyl ether of polypropylene glycol having a molecular weight of 1,000 to 1,500) or mono- arid poly carboxy lie esters thereof such as, for example, the acetic esters, mixed Cj-Cg fatty acid esters, or the Cr, oxo acid diester of tetraethylene glycol.

|0045] Yet another class of useful synthetic lubricating oils include, but are not limited to, the esters of dicarboxylic acids e.g., phthaiic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acids, alkyl malonic acids, and alkenyl malonic acids, with a variety of alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, di ethylene glycol monoether, and propylene glycol. Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by- reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2- ethylhexanoic acid.

[0046] Esters useful as synthetic oils also include, but are not limited to, those made from carboxylic acids having from about 5 to about 12 carbon atoms with alcohols, e.g., methanol, and ethanol, polyois and polyol ethers such as neopentyi glycol, trimethylol propane, pentaerythritol, dipentaerythntol, and tripentaerythritol.

[0047] Silicon-based oils such as, for example, polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxy-siloxane oils and silicate oils, comprise another useful class of synthetic lubricating oils. Specific examples of these include, but are not limited to, tetraethyl silicate, tetra-isopropyl silicate, tetra-(2-ethylhexyi) silicate, tetra-(4-methyl-hexyl)silicate, tetra-(p- tert-butylphenyl)silieate, hex l -(4-meth l-2-pentoxy)disil oxane, poly(methyl)siloxanes, and poly(methyiphenyi)siloxanes. Still yet other useful synthetic lubricating oils include, but are not limited to, liquid esters of phosphorus containing acids, e.g., tricresyl phosphate, trioctyl phosphate, and diethyl ester of decane phosphonic acid, and polymeric tetrahydrofurans.

[0048] The lubricating oil may be derived from unrefined, refined, and rerefmed oils, either natural, synthetic, or mixtures of two or more of any of these of the type disclosed hereinabove. Unrefined oils are those obtained directly from a natural or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include, but are not limited to, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. These purification techniques are known to those of skill in the art and include, for example, solvent extractions, secondary distillation, acid or base extraction, filtration, percolation, hydrotreating, dewaxing.

erefined oils are obtained by treating used oils in processes similar to those used to obtain refined oils. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.

[0049] Lubricating oil base stocks derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforesaid natural and/or synthetic base stocks. Such wax isomerate oil is produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst.

[0050] Natural waxes are typically the slack waxes recovered by the solvent dewaxing of mineral oils. Synthetic waxes are typically the wax produced by the Fischer-Tropsch process.

[0051] The Overbased Alkylaryl Sulfonate Detergent:

[0052] The overbased alkylaryl sulfonate detergent is an alkaline earth alkylaryl sulfonate having a BN of at least 250, wherein the aryl radical is other than phenol and the alkyl group is a linear chain that contains between 14 to 40 carbon atoms. The overbased alkylaryl sulfonate detergent may be incorporated in the lubricating oil composition in an amount of 0.2 to 20.0 wt. %, preferably 2.5 to 10.0 wt. %, based on the total amount of the lubricating oil composition.

[0053] The overbased alkylaryl sulfonate detergent is preferably a high overbased detergent and has a Total Base Number (TBN, in terms of mg KOH/g as defined by ASTM 2896) of at least 250, preferably greater than 350, and more preferably greater than 450.

[0054] The aryl group in the overbased alkylaryl sulfonate detergent may be one aromatic compound or a mixture of aromatic compounds. Suitable aromatic compounds or the aromatic compound mixture comprise at least one of monocyclic aromatics, such as benzene, toluene, xylene, cumene or mixtures thereof. In one preferred embodiment the at least one aromatic moiety of the alkyl aromatic sulfonic acids or salts contains no hydroxyl groups. In one preferred embodiment, the at least one aromatic moiety of the alkyl aromatic sulfonic acids or salts compound is not a phenol. In one embodiment, the at least one aromatic compound or aromatic compound mixture is toluene.

[0055] The linear alkyl chain in the overbased alkylaryl sulfonate detergent contains between 14 and 40 carbon atoms, preferably from 14 to 24 carbon atoms, preferably from 20 to 24 carbon atoms. Preferably, the alkaline earth alkylaryl sulfonate is derived from a C-.4- C40 normal alpha olefin, more preferably from a C20-C24 normal alpha olefin.

[0056] The overbased alkylaryl sulfonate detergent may be prepared using any method known in the art. Generally, alkylaryl sulfonate detergents may be prepared by employing the following steps:

a. Neutralizing the alkylaryl sulfonic acid with a base;

b. Carbonating the neutralized alkylaryl sulfonic acid with a base and CO2 to produce an overbased alkylaryl sulfonate;

c. Removing any sediment and solvents.

[0057] In one embodiment, the overbased alkylaryl sulfonate detergent may be prepared by the method described in U.S. Patent No. 6,479,440 Example 1, the contents of which are herein incorporated by reference.

[0058] The source of base may be an alkaline earth metal base. Suitable alkaline earth metal bases that may be used for carrying out this step include the oxides or hydroxides of calcium, magnesium, barium, or strontium, and particularly of calcium oxide, calcium hydroxide, magnesium oxide, and mixtures thereof. In one embodiment, the alkaline earth metal base is slaked lime (calcium hydroxide).

[0059] The Overbased Isomerized Normal alpha Olefin Based Phenate Detergent:

[0060] The overbased isomerized normal alpha olefin based phenate detergent is an alkylated hydroxyl compound wherein the alkyl substituent of the hydroxyl compound is a residue of at least one olefin having from about 15 to about 99 wt. % branching. The isomerized olefin can be a C10-C40 olefin. In one embodiment, the isomerized olefin is a C ₁₄ - C24 olefin. In another embodiment, the isomerized olefin is a C20-C24 olefin.

[0061] The overbased isomerized normal alpha olefin based phenate detergent can be prepared by the processes described in U.S. Patent No. 8,580,717, Examples 1-13, the contents of which are herein incorporated by reference. The overbased isomerized normal alpha olefin based phenate detergent may be prepared by the following process:

a) alkylating at least one hydroxy aromatic compound with at least one isomerized olefin having from about 15 to about 99 wt. % branching obtained by isomerizing at least one normal alpha olefin having from about 10 to about 40 carbon atoms, to provide at least one alkylated hydroxy aromatic compound;

(b) neutralizing and sulfurizing the alkylated hydroxy aromatic compound in any order to provide at least one neutralized, sulfurized alkylated hydroxy aromatic compound; and

(c) overbasing the at least one neutralized, sulfurized alkylated hydroxy aromatic compound; wherein the hydroxy aromatic compound is a phenol, cresoi, xylenol, or a mixture thereof.

[0062] The alkaline earth metal bases that may be used for carrying out the overbasing process include the oxides or hydroxides of calcium, magnesium, barium, or strontium, and particularly of calcium oxide, calcium hydroxide, magnesium oxide, and mixtures thereof. In one embodiment, the alkaline earth metal base is slaked lime (calcium hydroxide).

[0063] The overbased isomerized normal alpha olefin based phenate detergent has a Total Base Number (TBN, in terms of mg KOH/g as defined by ASTM 2896) greater than 200, preferably greater than 250.

[0064] The amount of the overbased isomerized normal alpha olefin based phenate detergent in the lubricating oil composition ranges from 0.1 wt. % to about 20 wt. %, based on the total weight of the lubricating oil composition. In one embodiment, the amount of the overbased isomerized normal alpha olefin based phenate detergent in the lubricating oil composition ranges from about 0.1 wt. % to about 5 wt. %, based on the total weight of the lubricating oil composition.

[0065] The weight ratio of the overbased alkylaryl sulfonate detergent to the overbased isomerized normal alpha olefin based phenate detergent ranges from 1 :9 to 9: 1, preferably 1 : 1.5 to 9: 1, preferably 1 :5 to 8: 1, more preferably 1 :2 to 6: 1.

[0066] Other Additives:

[0067] The lubricating oil compositions of the present invention may also contain other conventional additives for imparting auxiliary functions to give a finished lubricating oil composition in which these additives are dispersed or dissolved. For example, the lubricating oil compositions can be blended with antioxidants, anti-wear agents, detergents such as metal detergents, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, antifoaming agents, co-solvents, package compatibilisers, corrosion-inhibitors, ashless dispersants, dyes, extreme pressure agents, and mixtures thereof. A variety of the additives are known and commercially available. These additives, or their analogous compounds, can be employed for the preparation of the lubricating oil compositions of the in vention by the usual blending procedures.

[0068] Examples of antioxidants include, but are not limited to, aminic types, e.g., di phenyl amine, phenyl-alpha-napthyl-amine, N,N-di(alkylphenyl) amines, and alkylated phenylene-diamines: phenolics such as, BHT, stericaliy hindered alkyl phenols, such as 2,6- di-teri-butyiphenol, 2,6-di-teri-but l-p-cresol and 2,6-di-tert-butyl-4-(2-octyl-3-propanoic) phenol; and mixtures thereof. The amount of the antioxidant may vary from about 0.01 wt% to about 5 wt.%.

[0069] Examples of antiwear agents include, but are not limited to, zinc

dialkyldithiophosphates and zinc diaryldithiophosphates, e.g., those described in an article by- Bora et al. entitled "Relationship between Chemical Structure and Effectiveness of Some Metallic Dialkyl- and Diaryl-dithiophosphates in Different Lubricated Mechanisms,' ^" appealing in Lubrication Science 4-2 Jan. 1992, see, for example, pages 97-100; aryl phosphates and phosphites; sulfur-containing esters; phosphosulfur compounds; metal or ash- free dithiocarbamates, xanthates, alkyl sulfides, and mixtures thereof. The amount of the antiwear agent may vary from about 0.01 to about 5 wt.%.

[0070] Examples of rust inhibitors include, but are not limited to, noniomc polyoxyalkylene agents, e.g., polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether,

poly oxy ethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oieyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate; stearic acid and other fatty acids; dicarboxylic acids; metal soaps; fatty acid amine salts; metal salts of heavy sulfonic acid; partial carboxylic acid ester of polyhydric alcohol; phosphoric esters; (short- chain) alkenyl succinic acids, partial esters thereof and nitrogen-containing derivatives thereof; synthetic alkaryisulfonates, e.g., metal dinonylnaphthalene sulfonates; and mixtures thereof. The amount of the rust inhibitor may vary from about 0.01 wt. % to about 10 wt. %

[0071] Examples of friction modifiers include, but are not limited to, alkoxylated fatty amines; berated fatty epoxides; fatty phosphites; fatty epoxides; fatty amines; borated alkoxylated fatty amines; metal salts of fatty acids; fatty acid amides; and fatty imidazolines as disclosed in U.S. Pat. No. 6,372,696, the contents of which are incorporated herein by reference; friction modifiers obtained from a reaction product of a C4 to C 75, preferably a C ₆ to€24, and most preferably a Ce to C20, fatty acid ester and a nitrogen-containing compound selected from the group consisting of ammonia, an alkanolamine: and mixtures thereof. The amount of the friction modifier may vary from about 0.01 wt. % to about 10 wt. % [0072] Examples of antifoaming agents include, but are not limited to, polymers of alkyl methacrylate; polymers of dimethylsilicone, and mixtures thereof. The amount of the antifoaming agent may vary from about 0.01 to about 1 wt. %.

[0073] Examples of a pour point depressant include, but are not limited to,

polymethacrylates, alkyl acrvlate polymers, alkyl methacrylate polymers, diftetra-paraffin phenol )ph thai ate, condensates of tetra-paraffin phenol, condensates of a chlorinated paraffin with naphthalene, and combinations thereof. In one embodiment, a pour point depressant comprises an ethylene-vmyl acetate copolymer, a condensate of chlorinated paraffin and phenol, polyalkyl styrene, and combinations thereof. The amount of the pour point depressant may vary from about 0.01 wt. % to about 10 wt. %.

[0074] Examples of a demulsifier include, but are not limited to, anionic surfactants (e.g., alkyl-naphthalene sulfonates and alkyl benzene sulfonates), noniomc alkoxylated aikylphenol resins, polymers of alkyl en e oxides (e.g., polyethylene oxide, polypropylene oxide, and block copolymers of ethylene oxide and propylene oxide), esters of oil soluble acids,

poly oxy ethylene sorbitan ester, and combinations thereof. The amount of the demulsifier may vary from about 0.01 wt. % to about 10 wt. %.

[0075] Examples of a corrosion inhibitor include, but are not limited to, half esters or amides of dodecylsuccinic acid, phosphate esters, t iophosphates, alkyl imidazoli es, sarcosines, and combinations thereof. The amount of the corrosion inhibitor may vary from about 0.01 wt. % to about 5 wt. %.

[0076] Examples of an extreme pressure agent include, but are not limited to, sulfurized animal or vegetable fats or oils, sulfurized animal or vegetable fatty acid esters, fully or partially esterified esters of tnvalent or pentavalent acids of phosphorus, sulfurized olefins, dihydrocarbyl po!ysulfides, sulfurized Diels-Alder adducts, sulfurized dicyclopentadiene, sulfurized or co-sulfurized mixtures of fatty acid esters and monounsaturated olefins, co- sulfunzed blends of fatty acid, fatty acid ester and alpha-olefin, functionally-substituted dihydrocarbyl polysuliides, thia- aldehydes, thia-ketones, epithio compounds, sulfur- containing acetal derivatives, co-sulfurized blends of terpene and acyclic olefins, polysulfide olefin products, amine salts of phosphoric acid esters or thiophosphoric acid esters, and combinations thereof. The amount of the extreme pressure agent may vary from about 0.01 wt. % to about 5 wt. %.

[0077] The lubricating oil compositions of the invention can be prepared by admixing, through conventional techniques, an appropriate amount of the first detergent and second detergent and any optional additives with a base oil of lubricating viscosity.

[0078] The TBN of lubricating oil composition of the invention is 5 to 120, preferably 5- 100, preferably 10-100, preferably 15-100, preferably 20-100, preferably 5 to 70, more preferably 15 to 40, more preferably 5 to 40, more preferably 20 to 70, more preferably 20 to 50, and morepreferably 15 to 70 mgKOH/g.

[0079] The viscosity grade of the lubricating oil composition of the invention is SAE 20- 50. In one embodiment, the lubricating oil has a viscosity grade of SAE 20. In one embodiment, the lubricating oil has a viscosity grade of SAE 30. In one embodiment, the lubricating oil has a viscosity grade of SAE 40. in one embodiment, the lubricating oil has a viscosity grade of SAE 50.

[0080] The lubricating base oil has a kinematic viscosity at 100° C of 5.6 to 21.9 ratf/s. preferably 9.3 to 21.9 rnn /s, preferably 9.3 to 16.3 mm /s, preferably 9.3 to 12.5 mrn ² /s, preferably 12,5 to 16.3 mm ² /s, preferably 16.3 to 21 .9 mm ² /s.

EXAMPLES

[0081] The following non-limiting examples are illustrative of the invention.

[0082] Lubricating oil compositions were formulated by blending the components indicated in Tables 1-3.

[0083] The resulting compositions were tested using the following test methods:

[0084] Kornatsu Hot Tube (KHT) Test: A lubricating oil composition is passed through a temperature-controlled glass tube for a period of time by employing a suitable air flow. The glass tube is then cooled and washed, and the color of any lacquer deposition remaining on the inner surface of the glass tube is determined using a color merit rating ranging from 0 to 10 (0=black and 10=clean). In cases in which the glass tubes are completely blocked with deposits, the test result is recorded as "blocked". Superior detergency is illustrated by higher KHT values sustained over higher temperature ranges.

[0085] Differential Scanning Calorimetry: This test is used to evaluate thin film oxidation stability of test oils, in accordance with ASTM D-6186. Heat flow to and from test oil in a sample cup is compared to a reference cup during the test. The Oxidation Onset Temperature is the temperature at which the oxidation of the test oil starts. The Oxidation Induction Time is the time at which the oxidation of the test oil starts. The oxidation reaction results in an exothermic reaction which is shown by the heat flow. The Oxidation Induction Time is calculated to evaluate the thin film oxidation stability of the test oil. A copy of this test method may be obtained from ASTM International at 100 Barr Harbor Drive, PO Box 0700, West Conshohocken, Pa. 19428-2959 and is herein incorporated by reference for all purposes. Better thin film oxidation stability is evident by overall higher oxidation induction times.

[0086] Modified Institute of Petroleum 48 (MIP-48) Test, Viscosity Increase: Two samples of lubricating oil composition are heated for a period of time. Nitrogen is passed through one of the test samples while air is passed through the other sample. The two samples are then cooled, and the viscosities of each sample determined. The oxidation-based viscosity increase for each lubricating oil composition is calculated by subtracting the kinematic viscosity at 100°C for the nitrogen-blown sample from the kinematic viscosity at 100°C for the air-blown sample, and dividing the subtraction product by the kinematic viscosity at 100°C for the nitrogen blown sample. Better stability against oxidation-based viscosity increase is evidenced by lower viscosity increase.

[0087] Modified Institute of Petroleum 48 (MIP-48) Test, BN Depletion: Two samples of the test lubricant are heated for a specified period of time. Nitrogen is passed through one of the test samples while air is passed through the other. The samples are cooled and the TBN of both samples is determined. The MIP-48 TBN Depletion is calculated by subtracting the TBN for the nitrogen blown sample from the TBN for the air blown sample, dividing the result of the subtraction product by the TBN for the nitrogen blown sample, and multipl ing the result by 100 to obtain the % MIP-48 TBN Depletion. Lower percentage of BN depletion is desired.

[0088] Centrifuge Water Tolerance: A centrifuge containing 5100g oil at 80°C is constantly recirculated at 50L/h. Fresh water is fed to the oil continuously at lL/h during 3 hours of centrifuging. The final weight of deposits on the centrifuge disc, distributor and bowl is measured. Calcium, phosphorous, zinc, and water contents of the oil are measured before and after testing. Better water tolerance performance is indicated by higher retention of calcium, phosphorous, or zinc in the lubricating oil.

[0089] The following components are used below in formulating a marine diesel lubricant composition of the examples.

[0090] Detergent A: An oil concentrate of an overbased calcium alkyltoluene sulfonate detergent; wherein the alkyl group is derived from C20 to C24 linear alpha olefins. This additive concentrate contained 16.1 wt. % Ca, and about 38.7 wt. % diluent oil, and had a TBN of 420. On an active basis, the TBN of this additive (absent diluent oil) is 685. [0091] Detergent B: An oil concentrate of an overbased sulfurized calcium phenate derived from propylene tetramer. This additive contained 9.6 wt. % Ca, and about 31.4 wt. % diluent oil, and had a TBN of 260.

[0092] Detergent C: An oil concentrate of an overbased sulfurized calcium phenate derived from Ci4 normal alpha olefin with an isomerization level no less than 85% and a CMR of 0.44. This additive contained 9.8 wt. % Ca, and about 31.4 wt. % diluent oil and had a TBN of about 260.

[0093] Detergent D: An oil concentrate of an overbased sulfurized calcium phenate derived from Ci4 normal alpha olefin with an isomerization level no less than 85% and a CMR of 0.57. This additive contained about 10.2 wt. % Ca, and about 31.4 wt. % diluent oil and had a TBN of about 260.

[0094] Detergent E: An oil concentrate of an overbased sulfurized calcium phenate derived from C20-24 normal alpha olefin with an isomerization level of 65% and a CMR of 0.32. This additive contained about 9.45 wt. % Ca, and about 31.4 wt. % diluent oil and had a TBN of about 260.

[0095] Detergent F: An oil concentrate of an overbased sulfurized calcium phenate derived from C20-24 normal alpha olefin with an isomerization level of 65% and a CMR of 0.46. This additive contained 9.9 wt. % Ca, and about 31.4 wt. % diluent oil and had a TBN of about 260.

[0096] Wear inhibitor: Secondary zinc dithiophosphate (ZnDTP) derived from a mixture of C4 and Ce alcohols, available from Chevron Oronite Company (San Ramon, CA)

[0097] Group I base oil was ExxonMobil CORE® 600N basestock, available from ExxonMobil (Irving, TX.).

[0098] Chevron RLOP 600N: Group II-based lubricating oil was Chevron RLOP 600N basestock, available from Chevron Products Company (San Ramon, CA.).

[0099] Example 1: The lubricating oil compositions of Example 1 were formulated by blending the components indicated in Table 1. Table 1

Type 20 BN Experimental Oil

SAE grade SAE 30/40

Components (m%) Comparative Comparative Test Example Test Example Test Example Test Example

Example 1 Example 2 1 2 3 4

Detergent A 4.90 4.41 4.41 4.42 4.41 4.42

Detergent B -- 0.74 -- -- -- --

Detergent C -- -- 0.73 -- -- --

Detergent D -- -- -- 0.71 -- --

Detergent E -- -- -- -- 0.74 --

Detergent F -- -- -- -- -- 0.72

Wear inhibitor 0.70 0.70 0.70 0.70 0.70 0.70

Foam inhibitor 0.04 0.04 0.04 0.04 0.04 0.04

Group I base oil 94.36 94.11 94.12 94.13 94.11 94.12

Ratio of -- 5.4 5.4 5.4 5.4 5.4 sulfonate/phenate

Test Results

Komatsu Hot Tube 7.5 7.0 9.0 7.0 7.0 6.0 (300° C), rating

Komatsu Hot Tube 5.0 5.0 1.5 2.5 blocked 5.5 (310° C), rating

Komatsu Hot Tube blocked 0.0 blocked Blocked Not blocked (320° C), rating applicable

Differential Scanning 7.00 18.36 17.00 15.64 16.16 17.74 Calorimetry,

oxidation induction

time (min)

Modified IP-48, 116.9 95.1 95.2 83.2 94.4 90.7 vis 100 increase (%)

Modified IP-48, BN 35.5 37.3 36.0 36.7 35.5 36.2 depletion (%)

[00100] Example 2: The lubricating oil compositions of Example 2 were formulated by blending the components indicated in Tables 2. Table 2

Type 20 BN Experimental Oil

SAE grade SAE 30/40

Components (m%) Comparative Comparative Test Example Test Example Test Example Test Example

Example 3 Example 4 5 6 7 8

Detergent A 4.90 3.92 3.92 3.93 3.93 3.93

Detergent B -- 1.49 -- -- -- --

Detergent C -- -- 1.47 -- -- --

Detergent D -- -- -- 1.42 -- --

Detergent E -- -- -- -- 1.47 --

Detergent F -- -- -- -- -- 1.45

Wear inhibitor 0.70 0.70 0.70 0.70 0.70 0.70

Foam inhibitor 0.04 0.04 0.04 0.04 0.04 0.04

Group I base oil 94.36 93.85 93.87 93.91 93.86 93.88

Ratio of -- 2.4 2.4 2.4 2.4 2.4 sulfonate/phenate

Test Results

Komatsu Hot Tube 7.5 7.0 7.0 7.5 7.5 7.0 (300° C), rating

Komatsu Hot Tube 5.5 5.5 5.5 5.5 5.5 5.5 (310° C), rating

Komatsu Hot Tube blocked blocked blocked blocked blocked blocked (320° C), rating

Differential Scanning 9.18 16.03 19.92 19.85 18.81 20.37 Calorimetry, oxidation

induction time (min)

Modified IP-48, vis 100 108.0 81.6 68.4 76.0 86.8 66.0 increase (%)

Modified IP-48, BN 34.6 38.3 37.6 38.8 37.9 38.0 depletion (%)

[00101] Example 3: The lubricating oil compositions of Example 3 were formulated by

blending the components indicated in Tables 3. Table 3

Type 20 BN Experimental Oil

SAE grade SAE 30/40

Components Comparative Comparative Test Example Test Example Test Example Test Example (m%) Example 5 Example 6 9 10 11 12

Detergent A 4.90 2.94 2.94 2.94 2.94 2.94

Detergent B -- 2.97 -- -- -- --

Detergent C -- -- 2.94 -- -- --

Detergent D -- -- -- 2.86 -- --

Detergent E -- -- -- -- 2.94 --

Detergent F -- -- -- -- -- 2.91

Wear inhibitor 0.70 0.70 0.70 0.70 0.70 0.70

Foam Inhibitor 0.04 0.04 0.04 0.04 0.04 0.04

Group I base 94.36 93.35 93.38 93.46 93.38 93.41 oil

Ratio of 0.89 0.89 0.89 0.89 0.89 sulphonate/phen

ate

Test Results

Komatsu Hot 7.5 7.5 7.0 7.5 6.5 7.5 Tube (300° C),

rating

Komatsu Hot 5.5 5.5 4.5 5.0 4.5 4.5 Tube (310° C),

rating

Komatsu Hot 4.0 4.0 3.5 4.0 3.0 3.5 Tube (320° C),

rating

Differential 8.22 21.76 21.43 22.49 20.96 22.23

Scanning

Calorimetry,

oxidation

induction time

(min)

Modified IP- 122.5 63.2 67.8 60.7 72.3 48.4 48, visl00

increase (%)

Modified IP- 34.8 38.3 43.3 43.8 42.5 42.6 48, BN

depletion (%) Centrifuge 33.2 29.7 30.9 34.8 30.7 31.6 Water

Tolerance, total

deposits (g)

Centrifuge 96.1 98.9 99.3 94.1 98.5 95.6 Water

Tolerance, Ca

retention (%)

Centrifuge 79.25 50.0 63.3 79.2 75.5 73.5 Water

Tolerance, P

retention (%)

Centrifuge 94.5 98.2 101.8 96.4 98.2 98.2 Water

Tolerance, Zn

retention (%)

Centrifuge 0.47 0.36 0.38 0.27 0.34 0.33 Water

Tolerance,

water (m%)

[00102] Example 4: The lubricating oil compositions of Example 4 were formulated by blending the components indicated in Table 4.

[00103] Table 1-4 demonstrate that test examples which involve the phenates derived from isomerized olefin show comparable performance in Komatsu Hot Tube and MIP test with the comparative examples. The test examples also show comparable or improved water tolerance comparing to the comparative examples.

[00104] Example 5: The lubricating oil compositions of Example 5 were formulated by blending the components indicated in Table 5.

[00105] Table 5 demonstrate that at high BN the test examples which involve the phenates derived from isomerized olefin show comparable performance in Komatsu Hot Tube and MIP test with the comparative examples.

[00106] It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the functions described above and implemented as the best mode for operating the present invention are for illustration purposes only. Other arrangements and methods may be implemented by those skilled in the art without departing from the scope and spirit of this invention. Moreover, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.