(12) United States Patent
`Hartley et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,723,685 B2
`Apr. 20, 2004
`
`US006723685B2
`
`(54) LUBRICATING OIL COMPOSITION
`
`(75) Inventors: Rolfe J. Hartley, Cranbury, NJ (US);
`Malcolm waddoups, west?eld, NJ
`(Us)
`
`.
`_
`.
`(73) Asslgnee' In?neum Internatlonal Ltd‘ (GB)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U'S'C' 154(k)) by 0 days‘
`
`(21) APP1-N0-r10/117,679
`.
`(22) Filed:
`Apr. 5, 2002
`
`4,702,850 A * 10/1987 Gutierrez et a1. ......... .. 508/197
`6,074,993 A * 6/2000 Waddoups et a1. ........ .. 508/364
`6,143,701 A 11/2000 Bo?a
`RE37,363 E * 9/2001 Gatto et a1. ............... .. 508/364
`6,300,291 B1
`10/2001 Hartley et a1. .... ..
`6,329,328 B1 * 12/2001 Koganei et a1. .......... .. 508/365
`6,444,624 B1
`9/2002 Walker et a1. ............ .. 508/363
`6,500,786 B1 * 12/2002 Hartley et a1. ............ .. 508/365
`
`EP
`EP
`EP
`WO
`WO
`
`FOREIGN PATENT DOCUMENTS
`0 855 437 A1
`7/1998
`C10M/135/18
`1 013 749 A2
`6/2000
`...... .. C10M/141/08
`1 013 749 A3
`1/2001
`...... .. C10M/141/08
`Wo95/07962 A1
`3/1995
`...... .. C10M/141/06
`W099 60080 A1 11 1999
`...... .. C10M 141 10
`/
`/
`/
`/
`
`(65)
`
`Prior Publication Data
`
`*
`
`'
`'t d b
`C1 6
`y exammer
`
`Us 2OO3/O199399 A1 Oct‘ 23’ 2003
`
`Primary Exammer—Ellen M McAvoy
`
`(51) Int. c1.7 ........................................... .. C10M 141/12
`(52) U-S- Cl- --------------------- -- 508/365; 508/371; 508/372;
`508/374; 508/379; 508/391; 508/445; 508/501
`(58) Field of Search ........................................ .. 508/365
`_
`References Clted
`U'S' PATENT DOCUMENTS
`
`(56)
`
`8/1979 Coupland et a1. ..... .. 252/32.7 E
`4,164,473 A
`4,176,073 A 11/1979 Ryer et a1. ............ .. 252/327 E
`4,176,074 A 11/1979 Coupland et a1. ..... .. 252/32.7 E
`4,192,757 A
`3/1980 Brewster ............. .. 252/327 E
`4,201,683 A
`5/1980 Brewster ............. .. 252/32.7 E
`4,248,720 A
`2/1981 Coupland et a1. ........ .. 252/427
`4,289,635 A
`9/1981 Schroeck ........ ..
`.. 252/327 E
`4,479,883 A 10/1984 Shaub et a1. .......... .. 252/32.7 E
`
`ABSTRACT
`(57)
`A lubricating oil composition comprising a) an oil of lubri
`cating viscosity having a viscosity index of at least 95; b) at
`least one calcium detergent; c) at least one oil soluble
`molybdenum compound; d) at least one organic ashless
`nitrogen-free friction modi?er; and e) at least one metal
`dihydrocarbyldithiophosphate compound, the composition
`havmg a Noack volatility of about 15 Wt. % or less, from
`0.05 to 0.6 Wt. % calcium from the calcium detergent,
`molybdenum in an amount of at least 10 ppm from the
`molybdenum Compound, and phosphorus from the metal
`dihydrocarbyldithiophosphate Compound in an mount up to
`about 0 1 Wt %
`'
`'
`'
`
`20 Claims, N0 Drawings
`
`ORONITE EXHIBIT 1001
`
`Page 1 of 8
`
`

`

`US 6,723,685 B2
`
`1
`LUBRICATING OIL COMPOSITION
`
`The present invention relates to lubricating oil compo
`sitions. More particularly, the present invention relates to
`lubricating oil compositions, Which exhibit simultaneously
`improved loW temperature valve train Wear performance,
`excellent compatibility With ?uoroelastomer materials com
`monly used for seals in modern internal combustion engines,
`and improved fuel economy properties.
`BACKGROUND OF THE INVENTION
`Lubricating oil compositions used to lubricate internal
`combustion engines contain base oil of lubricating viscosity,
`or a mixture of such oils, and additives used to improve the
`performance characteristics of the oil. For example, addi
`tives are used to improve detergency, to reduce engine Wear,
`to provide stability against heat and oxidation, to reduce oil
`consumption, to inhibit corrosion, to act as a dispersant, and
`to reduce friction loss. Some additives provide multiple
`bene?ts, such as dispersant-viscosity modi?ers. Other
`additives, While improving one characteristic of the lubri
`cating oil, have an adverse effect on other characteristics.
`Thus, to provide lubricating oil having optimal overall
`performance, it is necessary to characteriZe and understand
`all the effects of the various additives available, and care
`fully balance the additive content of the lubricant.
`It has been proposed in many patents and articles (for
`example, US. Pat. Nos. 4,164,473; 4,176,073; 4,176,074;
`4,192,757; 4,248,720; 4,201,683; 4,289,635; and 4,479,883)
`that oil-soluble molybdenum compounds are useful as lubri
`cant additives. In particular, the addition of molybdenum
`compounds to oil, particularly molybdenum dithiocarbam
`ate compounds, provides the oil With improved boundary
`friction characteristics and bench tests demonstrate that the
`coef?cient of friction of oil containing such molybdenum
`compounds is generally loWer than that of oil containing
`organic friction modi?ers. This reduction in coef?cient of
`friction results in improved antiWear properties and may
`contribute to enhanced fuel economy in gasoline or diesel
`?red engines, including both short- and long-term fuel
`economy properties (i.e., fuel economy retention
`properties). To provide antiWear effects, molybdenum com
`pounds are generally added in amounts introducing from
`about 350 ppm up to 2,000 ppm of molybdenum into the oil.
`While molybdenum compounds are effective antiWear
`agents and may further provide fuel economy bene?ts, such
`molybdenum compounds are expensive relative to more
`conventional, metal-free (ashless) organic friction modi?ers
`US. Pat. No. 6,300,291 discloses a lubricating oil com
`position having a speci?ed Noack volatility containing a
`base oil of a speci?ed viscosity index, calcium-based
`detergent, Zinc dihydrocarbyldithiophosphate (ZDDP) anti
`Wear agent, a molybdenum compound and a nitrogen
`containing friction modi?er. The molybdenum compound
`Was used in an amount providing the formulated lubricant
`With up to 350 ppm of molybdenum. The claimed materials
`are described as providing fuel economy bene?ts compared
`to compositions containing only molybdenum compounds.
`Modern internal combustion engines include numerous
`gaskets and other seals formed of ?uoroelastomer materials,
`such as VitonTM. Nitrogen-containing additives are sus
`pected of, over time, contributing to the deterioration of such
`materials. Therefore, it Would be desirable to ?nd a lubri
`cating oil composition that provides improved fuel economy
`bene?t; demonstrates excellent Wear protection
`characteristics, is relatively loW in cost, and is free of
`nitrogen-containing friction modi?ers.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`It has noW been found that the addition of small amounts
`of one or more oil soluble molybdenum compounds, in
`combination With an ashless, organic nitrogen-free friction
`modi?er, ZDDP and a calcium detergent provide loW cost
`lubricating oils having a demonstrable fuel economy bene?t;
`excellent Wear protection characteristics, and reduced
`adverse effects on engine seals formed of VitonTM and
`similar ?uoroelastomers.
`The present invention also provides many additional
`advantages that shall become apparent as described beloW.
`
`SUMMARY OF THE INVENTION
`
`In accordance With a ?rst aspect, the invention provides a
`lubricating oil composition displaying excellent loW tem
`perature valve train Wear performance, improved fuel
`economy retention properties and compatibility With
`?uoroelastomer-based engine seals, Which composition
`comprises an oil of lubricating viscosity having a viscosity
`index (VI) of at least 95; a calcium detergent in an amount
`introducing from about 0.05 to about 0.6 Wt. % calcium into
`the composition; an amount of a metal dihydrocarbyldithio
`phosphate compound introducing up to 0.1 Wt. % (1000
`ppm) of phosphorus into the composition; at least one
`molybdenum compound in an amount suf?cient to provide
`the composition With at least 10 ppm of molybdenum; and
`an effective amount of at least one organic, nitrogen-free,
`ashless friction modi?er; the composition having a Noack
`volatility of less than 15%.
`In accordance With a second aspect, the invention is
`directed to a method of improving the fuel economy, seal life
`and/or the Wear characteristics of an internal combustion
`engine, Which method comprises the steps of lubricating an
`internal combustion engine With a lubricating oil composi
`tion of the ?rst aspect and operating the engine.
`In accordance With a third aspect, the invention is directed
`to the use of a lubricating oil composition of the ?rst aspect
`to improve the fuel economy, seal life and/or the Wear
`characteristics of an internal combustion engine.
`Other and further objects, advantages and features of the
`present invention Will be understood by reference to the
`folloWing.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`The oil of lubricating viscosity can be at least one oil
`selected from the group consisting of Group I, Group II, or
`Group III base stocks or base oil blends of the aforemen
`tioned base stocks provided that the viscosity of the base oil
`or base oil blend is at least 95 and alloWs for the formulation
`of a lubricating oil composition having a Noack volatility,
`measured by determining the evaporative loss in mass
`percent of an oil after 1 hour at 250° C. according to the
`procedure of ASTM D5880, of less than 15%. In addition,
`the oil of lubricating viscosity may be one or more Group IV
`or Group V base stocks or combinations thereof or base oil
`mixtures containing one or more Group IV or Group V base
`stocks in combination With one or more Group I, Group II
`and/or Group III base stocks.
`The most preferred oils for fuel economy retention, are:
`(a) Base oil blends of Group III base stocks With Group
`I or Group II base stocks, Where the combination has a
`viscosity index of at least 110; or
`(b) Group III, IV or V base stocks or base oil blends of
`more than one Group III, IV or V base stocks, Where the
`viscosity index is betWeen about 120 to about 140.
`
`Page 2 of 8
`
`

`

`US 6,723,685 B2
`
`3
`De?nitions for the base stocks and base oils in this
`invention are the same as those found in the American
`Petroleum Institute (API) publication “Engine Oil Licensing
`and Certi?cation System”, Industry Services Department,
`Fourteenth Edition, December 1996, Addendum 1, Decem
`ber 1998. Said publication categorizes base stocks as fol
`loWs:
`a) Group I base stocks contain less than 90 percent
`saturates and/or greater than 0.03 percent sulfur and have a
`viscosity index greater than or equal to 80 and less than 120
`using the test methods speci?ed in Table E-1.
`b) Group II base stocks contain greater than or equal to 90
`percent saturates and less than or equal to 0.03 percent sulfur
`and have a viscosity index greater than or equal to 80 and
`less than 120 using the test methods speci?ed in Table E-1.
`c) Group III base stocks contain greater than or equal to
`90 percent saturates and less than or equal to 0.03 percent
`sulfur and have a viscosity index greater than or equal to 120
`using the test methods speci?ed in Table E-1.
`d) Group IV base stocks are polyalphaole?ns (PAO).
`e) Group V base stocks include all other base stocks not
`included in Group I, II, III, or IV.
`
`TABLE E-1
`
`Analytical Methods for Base Stock
`
`Property
`
`Saturates
`Viscosity Index
`Sulfur
`
`Test Method
`
`ASTM D 2007
`ASTM D 2270
`ASTM D 2622
`ASTM D 4294
`ASTM D 4927
`ASTM D 3120
`
`For the lubricating oil compositions of this invention, any
`suitable oil-soluble organo-molybdenum compound having
`friction modifying and/or anti-Wear properties in lubricating
`oil compositions may be employed. As an example of such
`oil-soluble organo-molybdenum compounds, there may be
`mentioned the dithiocarbamates, dithiophosphates,
`dithiophosphinates, xanthates, thioxanthates, sul?des, and
`the like, and mixtures thereof. Particularly preferred are
`molybdenum dithiocarbamates, dialkyldithiophosphates,
`alkyl xanthates and alkylthioxanthates.
`The molybdenum compound may be mono-, di-, tri- or
`tetra-nuclear. Dinuclear and trinuclear molybdenum com
`pounds are preferred. The molybdenum compound is pref
`erably an organo-molybdenum compound. More preferably,
`the molybdenum compound is selected from the group
`consisting of molybdenum dithiocarbamates (MoDTC),
`molybdenum dithiophosphates, molybdenum
`dithiophosphinates, molybdenum xanthates, molybdenum
`thioxanthates, molybdenum sul?des and mixtures thereof.
`Most preferably, the molybdenum compound is present as a
`molybdenum dithiocarbamate or a trinuclear organo
`molybdenum compound.
`Additionally, the molybdenum compound may be an
`acidic molybdenum compound. These compounds Will react
`With a basic nitrogen compound as measured by ASTM test
`D-664 or D-2896 titration procedure and are typically
`hexavalent. Included are molybdic acid, ammonium
`molybdate, sodium molybdate, potassium molybdate, and
`other alkaline metal molybdates and other molybdenum
`salts, e.g., hydrogen sodium molybdate, MoOCl4, MoO2Br2,
`Mo2O3Cl6, molybdenum trioxide or similar acidic molyb
`denum compounds. Alternatively, the compositions of the
`present invention can be provided With molybdenum by
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`molybdenum/sulfur complexes of basic nitrogen compounds
`as described, for example, in US. Pat. Nos. 4,263,152;
`4,285,822; 4,283,295; 4,272,387; 4,265,773; 4,261,843;
`4,259,195 and 4,259,194; and WO 94/06897.
`Among the molybdenum compounds useful in the com
`positions of this invention are organo-molybdenum com
`pounds of the formulae
`
`Mo(ROCS2)4 and
`MO(RSCS2)4
`Wherein R is an organo group selected from the group
`consisting of alkyl, aryl, aralkyl and alkoxyalkyl, generally
`of from 1 to 30 carbon atoms, and preferably 2 to 12 carbon
`atoms and most preferably alkyl of 2 to 12 carbon atoms.
`Especially preferred are the dialkyldithiocarbamates of
`molybdenum.
`One class of preferred organo-molybdenum compounds
`useful in the lubricating compositions of this invention are
`trinuclear molybdenum compounds, especially those of the
`formula Mo3SkLnQZ and mixtures thereof Wherein L are
`independently selected ligands having organo groups With a
`suf?cient number of carbon atoms to render the compound
`soluble or dispersible in the oil, n is from 1 to 4, k varies
`from 4 through 7, Q is selected from the group of neutral
`electron donating compounds such as Water, amines,
`alcohols, phosphines, and ethers, and Z ranges from 0 to 5
`and includes non-stoichiometric values. At least 21 total
`carbon atoms should be present among all the ligands’
`organo groups, such as at least 25, at least 30, or at least 35
`carbon atoms.
`The ligands are independently selected from the group of
`
`and mixtures thereof, Wherein X, X1, X2, and Y are inde
`pendently selected from the group of oxygen and sulfur, and
`Wherein R1, R2, and R are independently selected from
`hydrogen and organo groups that may be the same or
`different. Preferably, the organo groups are hydrocarbyl
`groups such as alkyl (e.g., in Which the carbon atom attached
`to the remainder of the ligand is primary or secondary), aryl,
`substituted aryl and ether groups. More preferably, each
`ligand has the same hydrocarbyl group.
`The term “hydrocarbyl” denotes a substituent having
`carbon atoms directly attached to the remainder of the ligand
`and is predominantly hydrocarbyl in character Within the
`context of this invention. Such substituents include the
`folloWing:
`
`Page 3 of 8
`
`

`

`US 6,723,685 B2
`
`5
`1. Hydrocarbon substituents, that is, aliphatic (for
`example alkyl or alkenyl), alicyclic (for example cycloalkyl
`or cycloalkenyl) substituents, aromatic-, aliphatic- and
`alicyclic-substituted aromatic nuclei and the like, as Well as
`cyclic substituents Wherein the ring is completed through
`another portion of the ligand (that is, any tWo indicated
`substituents may together form an alicyclic group).
`2. Substituted hydrocarbon substituents, that is, those
`containing non-hydrocarbon groups Which, in the context of
`this invention, do not alter the predominantly hydrocarbyl
`character of the substituent. Those skilled in the art Will be
`aWare of suitable groups (e.g., halo, especially chloro and
`?uoro, amino, alkoxyl, mercapto, alkylmercapto, nitro,
`nitroso, sulfoxy, etc.).
`3. Hetero substituents, that is, substituents Which, While
`predominantly hydrocarbon in character Within the context
`of this invention, contain atoms other than carbon present in
`a chain or ring otherWise composed of carbon atoms.
`Importantly, the organo groups of the ligands have a
`sufficient number of carbon atoms to render the compound
`soluble or dispersible in the oil. For example, the number of
`carbon atoms in each group Will generally range betWeen
`about 1 to about 100, preferably from about 1 to about 30,
`and more preferably betWeen about 4 to about 20. Preferred
`ligands include dialkyldithiophosphate, alkylxanthate, and
`dialkyldithiocarbamate, and of these dialkyldithiocarbamate
`is more preferred. Organic ligands containing tWo or more of
`the above functionalities are also capable of serving as
`ligands and binding to one or more of the cores. Those
`skilled in the art Will realiZe that formation of the com
`pounds of the present invention requires selection of ligands
`having the appropriate charge to balance the core’s charge.
`Compounds having the formula Mo3SkLnQZ to have cat
`ionic cores surrounded by anionic ligands and are repre
`sented by structures such as
`
`s'MO ‘s
`
`S
`
`s//MO\\$,
`XLLiZ
`\g7
`
`and have net charges of +4. Consequently, in order to
`solubiliZe these cores the total charge among all the ligands
`must be —4. Four monoanionic ligands are preferred. With
`out Wishing to be bound by any theory, it is believed that tWo
`or more trinuclear cores may be bound or interconnected by
`means of one or more ligands and the ligands may be
`multidentate. This includes the case of a multidentate ligand
`having multiple connections to a single core. It is believed
`that oxygen and/or selenium may be substituted for sulfur in
`the core(s).
`Oil-soluble or dispersible trinuclear molybdenum com
`pounds can be prepared by reacting in the appropriate
`liquid(s)/solvent(s) a molybdenum source such as (NH4)
`2Mo3S13.n(H2O), Where n varies betWeen 0 and 2 and
`includes non-stoichiometric values, With a suitable ligand
`
`6
`source such as a tetralkylthiuram disul?de. Other oil-soluble
`or dispersible trinuclear molybdenum compounds can be
`formed during a reaction in the appropriate solvent(s) of a
`molybdenum source such as of (NH4)2Mo3S13.n(H2O), a
`ligand source such as tetralkylthiuram disul?de,
`dialkyldithiocarbamate, or dialkyldithiophosphate, and a
`sulfur abstracting agent such as cyanide ions, sul?te ions, or
`substituted phosphines. Alternatively, a trinuclear
`molybdenum-sulfur halide salt such as [M‘]2[Mo3S7A6],
`Where M‘ is a counter ion, and Ais a halogen such as Cl, Br,
`or I, may be reacted With a ligand source such as a dialky
`ldithiocarbamate or dialkyldithiophosphate in the appropri
`ate liquid(s)/solvent(s) to form an oil-soluble or dispersible
`trinuclear molybdenum compound. The appropriate liquid/
`solvent may be, for example, aqueous or organic.
`A compound’s oil solubility or dispersibility may be
`in?uenced by the number of carbon atoms in the ligand’s
`organo groups. In the compounds of the present invention,
`at least 21 total carbon atoms should be present among all
`the ligands’ organo groups. Preferably, the ligand source
`chosen has a suf?cient number of carbon atoms in its organo
`groups to render the compound soluble or dispersible in the
`lubricating composition.
`The terms “oil-soluble” or “dispersible” used herein do
`not necessarily indicate that the compounds or additives are
`soluble, dissolvable, miscible, or capable of being sus
`pended in the oil in all proportions. These do mean,
`hoWever, that they are, for instance, soluble or stably dis
`persible in oil to an extent suf?cient to exert their intended
`effect in the environment in Which the oil is employed.
`Moreover, the additional incorporation of other additives
`may also permit incorporation of higher levels of a particular
`additive, if desired.
`The lubricating compositions of the present invention
`contain the molybdenum compound in an amount providing
`the composition With at least 10 ppm of molybdenum. An
`amount of at least 10 ppm of molybdenum from a molyb
`denum compound has been found to be effective to provide
`a fuel economy bene?t in combination With an ashless,
`organic nitrogen-free friction modi?er. Preferably, the
`molybdenum from a molybdenum compound is present in
`an amount of from about 10 ppm to about 750 ppm, such as
`10 ppm to 350 ppm, more preferably from about 30 ppm to
`200 ppm, still more preferably in an amount of from about
`50 ppm to about 100 ppm, based on the total Weight of the
`lubricating composition. Because such molybdenum com
`pounds also provide antiWear credits to lubricating oil
`compositions, the use thereof alloWs for a reduction in the
`amount of metal dihydrocarbyl dithiophosphate antiWear
`agent (e.g., ZDDP) employed. Industry trends are leading to
`a reduction in the amount of ZDDP being added to lubri
`cating oils to reduce the phosphorous content of the oil to
`beloW 1000 ppm, such as to 250 ppm to 750 ppm, or 250
`ppm to 500 ppm. To provide adequate Wear protection in
`such loW phosphorous lubricating oil compositions, the
`molybdenum compound should be present in an amount
`providing at least 50 ppm by mass of molybdenum. The
`amount of molybdenum and/or Zinc may be determined by
`Inductively Coupled Plasma (ICP) emission spectroscopy
`using the method described in ASTM D5185.
`Organic, ashless (metal-free), nitrogen-free organic fric
`tion modi?ers useful in the lubricating oil compositions of
`the present invention are knoWn generally and include esters
`formed by reacting carboxylic acids and anhydrides With
`alkanols. Other useful friction modi?ers generally include a
`polar terminal group (eg carboxyl or hydroxyl) covalently
`bonded to an oleophilic hydrocarbon chain. Esters of car
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Page 4 of 8
`
`

`

`US 6,723,685 B2
`
`7
`boxylic acids and anhydrides With alkanols are described in
`US. Pat. No. 4,702,850. Examples of other conventional
`organic friction modi?ers are described by M. BelZer in the
`“Journal of Tribology” (1992), Vol. 114, pp. 675—682 and M.
`BelZer and S. Jahanmir in “Lubrication Science” (1988),
`Vol. 1, pp. 3—26.
`The organic friction modi?er is included in the lubricating
`oil compositions of the present invention in an amount
`effective to alloW the composition to reliably pass a
`Sequence VIB fuel economy test in combination With the
`molybdenum compound. For example, the organic ashless
`nitrogen-free friction modi?er may be added to the
`molybdenum-containing lubricating oil composition in an
`amount suf?cient to obtain a retained fuel economy
`improvement of at least 1.7% for an SAE 5W-20 lubricant,
`1.1% for a 5W-30 lubricant, and 0.6% for a 10W-30 lubri
`cant as measured at 96 hours (Phase II performance) in the
`ASTM Sequence VIB Fuel Economy Test. Typically, to
`provide the desired effect, the organic ashless nitrogen-free
`friction modi?er is added in an amount of from about 0.25
`Wt. % to about 2.0 Wt. % (AI), based on the total Weight of
`the lubricating oil composition. Preferred organic ashless
`nitrogen-free friction modi?ers are esters; a particularly
`preferred organic ashless nitrogen-free friction modi?er is
`glycerol monooleate (GMO).
`Ashless aminic friction modi?ers excluded from compo
`sitions of the present invention include oil-soluble alkoxy
`lated mono- and di-amines, Which improve boundary layer
`lubrication, but may contribute to the deterioration over time
`of ?uoroelastomer seal materials. One common class of such
`metal free, nitrogen-containing friction modi?er comprises
`ethoxylated amines. These amines are also excluded When in
`the form of an adduct or reaction product With a boron
`compound such as a boric oxide, boron halide, metaborate,
`boric acid or a mono-, di- or tri-alkyl borate.
`Metal-containing or ash-forming detergents function both
`as detergents to reduce or remove deposits and as acid
`neutraliZers or rust inhibitors, thereby reducing Wear and
`corrosion and extending engine life. Detergents generally
`comprise a polar head With a long hydrophobic tail, With the
`polar head comprising a metal salt of an acid organic
`compound. The salts may contain a substantially stoichio
`metric amount of the metal in Which they are usually
`described as normal or neutral salts, and Would typically
`have a total base number (TBN), as may be measured by
`ASTM D-2896 of from 0 to 80. It is possible to include large
`amounts of a metal base by reacting an excess of a metal
`compound such as an oxide or hydroxide With an acid gas
`such as carbon dioxide. The resulting overbased detergent
`comprises neutraliZed detergent as the outer layer of a metal
`base (e.g., carbonate) micelle. Such overbased detergents
`may have a TBN of 150 or greater, and typically from 250
`to 450 or more.
`KnoWn detergents include oil-soluble neutral and over
`based sulfonates, phenates, sulfuriZed phenates,
`thiophosphonates, salicylates, and naphthenates and other
`oil-soluble carboxylates of a metal, particularly the alkali or
`alkaline earth metals, e.g., sodium, potassium, lithium,
`calcium, and magnesium. The most commonly used metals
`are calcium and magnesium, Which may both be present in
`detergents used in a lubricant, and mixtures of calcium
`and/or magnesium With sodium. Particularly convenient
`metal detergents are neutral and overbased calcium sul
`fonates having TBN of from 20 to 450 TBN, and neutral and
`overbased calcium phenates and sulfuriZed phenates having
`TBN of from 50 to 450.
`In the present invention, one or more calcium-based
`detergents are used in an amount introducing from about
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`0.05 to about 0.6 Wt. % calcium into the composition. The
`amount of calcium may be determined by Inductively
`Coupled Plasma (ICP) emission spectroscopy using the
`method described in ASTM D5185. Preferably, the calcium
`based detergent is overbased and the total base number of
`the overbased calcium based detergent is betWeen about 150
`to 450. More preferably, the calcium-based detergent is an
`overbased calcium sulfonate detergent. The compositions of
`the present invention may further include either neutral or
`overbased magnesium-based detergents, hoWever,
`preferably, the lubricating oil compositions of the present
`invention Will be magnesium free.
`Metal dihydrocarbyl dithiophosphate antiWear agents that
`may be added to the lubricating oil composition of the
`present invention comprise dihydrocarbyl dithiophosphate
`metal salts Wherein the metal may be an alkali or alkaline
`earth metal, or aluminum, lead, tin, molybdenum,
`manganese, nickel, copper or preferably, Zinc. The Zinc salts
`are most commonly used in lubricating oil.
`Dihydrocarbyl dithiophosphate metal salts may be pre
`pared in accordance With knoWn techniques by ?rst forming
`a dihydrocarbyl dithiophosphoric acid (DDPA), usually by
`reaction of one or more alcohol or a phenol With P2S5 and
`then neutraliZing the formed DDPA With a metal compound.
`For example, a dithiophosphoric acid may be made by
`reacting mixtures of primary and secondary alcohols.
`Alternatively, multiple dithiophosphoric acids can be pre
`pared Where the hydrocarbyl groups on one are entirely
`secondary in character and the hydrocarbyl groups on the
`others are entirely primary in character. To make the metal
`salt, any basic or neutral metal compound could be used but
`the oxides, hydroxides and carbonates are most generally
`employed. Commercial additives frequently contain an
`excess of metal due to the use of an excess of the basic metal
`compound in the neutraliZation reaction.
`The preferred Zinc dihydrocarbyl dithiophosphates
`(ZDDP) are oil soluble salts of dihydrocarbyl dithiophos
`phoric acids and may be represented by the folloWing
`formula:
`
`R0 5 \LS
`
`, /
`RO
`
`Zn
`
`Wherein R and R‘ may be the same or different hydrocarbyl
`radicals containing from 1 to 18, preferably 2 to 12, carbon
`atoms and including radicals such as alkyl, alkenyl, aryl,
`arylalkyl, alkaryl and cycloaliphatic radicals. Particularly
`preferred as R and R‘ groups are alkyl groups of 2 to 8
`carbon atoms. Thus, the radicals may, for example, be ethyl,
`n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl,
`i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl,
`phenyl, butylphenyl, cyclohexyl, methylcyclopentyl,
`propenyl, butenyl. In order to obtain oil solubility, the total
`number of carbon atoms (i.e. R and R‘) in the dithiophos
`phoric acid Will generally be about 5 or greater. The Zinc
`dihydrocarbyl dithiophosphate can therefore comprise Zinc
`dialkyl dithiophosphates.
`To limit the amount of phosphorus introduced into the
`lubricating oil composition by ZDDP to no more than 0.1 Wt.
`% (1000 ppm), the ZDDP should preferably be added to the
`lubricating oil compositions in amounts no greater than from
`about 1.1 to 1.3 Wt. %, based upon the total Weight of the
`lubricating oil composition.
`Other additives, such as the folloWing, may also be
`present in lubricating oil compositions of the present inven
`tion.
`
`Page 5 of 8
`
`

`

`US 6,723,685 B2
`
`10
`
`15
`
`20
`
`25
`
`30
`
`Ashless dispersants comprise an oil soluble polymeric
`hydrocarbon backbone having functional groups that are
`capable of associating With particles to be dispersed.
`Typically, the dispersants comprise amine, alcohol, amide,
`or ester polar moieties attached to the polymer backbone
`often via a bridging group. The ashless dispersants may be,
`for example, selected from oil soluble salts, esters, amino
`esters, amides, imides, and oxaZolines of long chain hydro
`carbon substituted mono and dicarboxylic acids or their
`anhydrides; thiocarboxylate derivatives of long chain hydro
`carbons; long chain aliphatic hydrocarbons having a
`polyamine attached directly thereto; and Mannich conden
`sation products formed by condensing a long chain substi
`tuted phenol With formaldehyde and a polyalkylene
`polyamine.
`Viscosity modi?ers (VM) function to impart high and loW
`temperature operability to a lubricating oil. The VM used
`may have that sole function, or may be multifunctional.
`Multifunctional viscosity modi?ers that also function as
`dispersants are also knoWn. Suitable viscosity modi?ers are
`polyisobutylene, copolymers of ethylene and propylene and
`higher alpha-ole?ns, polymethacrylates,
`polyalkylmethacrylates, methacrylate copolymers, copoly
`mers of an unsaturated dicarboxylic acid and a vinyl
`compound, inter polymers of styrene and acrylic esters, and
`partially hydrogenated copolymers of styrene/isoprene,
`styrene/butadiene, and isoprene/butadiene, as Well as the
`partially hydrogenated homopolymers of butadiene and iso
`prene and isoprene/divinylbenZene.
`Oxidation inhibitors or antioxidants reduce the tendency
`of base stocks to deteriorate in service Which deterioration
`can be evidenced by the products of oxidation such as sludge
`and varnish-like deposits on the metal surfaces and by
`viscosity groWth. Such oxidation inhibitors include hindered
`phenols, alkaline earth metal salts of alkylphenolthioesters
`having preferably C5 to C12 alkyl side chains, calcium
`nonylphenol sul?de, ashless oil soluble phenates and sulfu
`riZed phenates, phosphosulfuriZed or sulfuriZed
`hydrocarbons, phosphorus esters, metal thiocarbamates and
`oil soluble copper compounds as described in US. Pat. No.
`4,867,890.
`Rust inhibitors selected from the group consisting of
`nonionic polyoxyalkylene polyols and esters thereof, poly
`oxyalkylene phenols, and anionic alkyl sulfonic acids may
`be used.
`Copper and lead bearing corrosion inhibitors may be
`used, but are typically not required With the formulation of
`the present invention. Typically such compounds are the
`thiadiaZole polysul?des containing from 5 to 50 carbon
`atoms, their derivatives and polymers thereof. Derivatives of
`1,3,4 thiadiaZoles such as those described in US. Pat. Nos.
`2,719,125; 2,719,126; and 3,087,932; are typical. Other
`similar materials are described in US. Pat. Nos. 3,821,236;
`3,904,537; 4,097,387; 4,107,059; 4,136,043; 4,188,299; and
`4,193,882. Other additives are the thio and polythio sulfe
`namides of thiadiaZoles such as those described in UK
`55
`Patent Speci?cation No. 1,560