Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Nitrogen and heavy metal – or nitrogen and aluminum – in the...
Reexamination Certificate
1997-04-18
2001-05-15
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Nitrogen and heavy metal, or nitrogen and aluminum, in the...
C508S364000, C508S370000, C508S379000, C508S445000, C556S038000, C556S057000
Reexamination Certificate
active
06232276
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improved lubricating compositions. The present invention also relates to lubricant compositions containing trinuclear molybdenum compounds.
BACKGROUND OF THE INVENTION
Molybdenum disulfide is a known lubricant additive. Unfortunately, it has certain known disadvantages some of which are caused by its insolubility in lubricating oils. Therefore, oil-soluble molybdenum sulfide-containing compounds have been proposed and investigated as lubricant additives. For example, U.S. Pat. No. 2,951,040 discloses an oil-soluble molybdic xanthate as useful in lubricating compositions.
U.S. Pat. No. 3,419,589 discloses the use of certain “sulfurized” molybdenum (VI) dithiocarbamates as lubricant additives. These additives are described as being oil-soluble or at least capable of being easily suspended in oils.
U.S. Pat. No. 3,840,463 discloses the use of certain metal dithiocarbamates or dithiophosphates in combination with metal-free additives that contain sulfur and phosphorus.
U.S. Pat. No. 4,966,719, U.S. Pat. No. 4,995,996, and U.S. Pat. No. 4,978,464 all relate to the preparation and use of molybdenum-sulfur compounds. However, the materials described in those patents are prepared from starting materials that are themselves either relatively expensive or difficult to prepare.
The foregoing patents are listed as representative of the very many known lubricant additives containing both molybdenum and sulfur.
As is known in the art, some lubricant additives function as antiwear agents, some as antioxidants, some as friction modifiers, and some as extreme pressure agents. Indeed, some additives may satisfy more than one of these functions. For example, metal dithiophosphates represent a class of additives which are known to exhibit antioxidant and antiwear properties. The most commonly used additives in this class are the zinc dialkyldithiophosphates (ZDDP) which provide excellent oxidation resistance and exhibit superior antiwear properties. Unfortunately, they do not have the most desirable lubricity. Therefore, lubricating compositions containing these zinc compounds may also require inclusion of friction modifiers, which may lead to other problems, such as additive compatibility, in formulating effective lubricant compositions. Additives may lose their effectiveness when combined with incompatible additives in a lubricating composition. Generally, extreme care must be exercised in combining various additives to assure both compatibility and effectiveness. For example, some friction modifiers affect metal surfaces differently than antiwear agents do. When both are present, friction-reducing and antiwear additives may compete for the surface of the metal parts which are subject to lubrication. This competition can produce a lubricant that is less effective than is suggested by the individual properties of the additive components.
Trinuclear molybdenum compounds have been reported, but they are either ionic or have ligands with short chain alkyl groups. The reported compounds are consequently not oil soluble, and they have not been reported as lubricating oil additives.
Thus, there remains a need for improved lubricating oil additives that can be used with standard lubricating oils, are compatible with other conventional lubricant additives, and can be made from readily available starting materials.
SUMMARY OF THE INVENTION
The invention is a lubricating composition comprising a major amount of an oil of lubricating viscosity and a minor amount of at least one trinuclear molybdenum compound. Preferably, the trinuclear molybdenum compound has a sulfur containing core and is represented by the formula Mo
3
S
k
L
n
Q
z
, wherein L represents independently selected ligands, n varies from 1 to 4 and is preferably 4, k varies from 4 through 7 and is preferably 4 or 7, Q is selected from the group consisting of neutral electron donating compounds including water, amines, alcohols, phosphines, and ethers, and z ranges from 0 to 5.
In another embodiment, the invention relates to mixtures of such compounds.
The lubricant compositions according to this invention have excellent antiwear, antioxidant, and friction-reducing properties. The lubricant compositions of the present invention may also be compatible with other standard additives used in formulating commercial lubricating compositions and can be made from readily available starting materials.
In still another embodiment, the invention relates to a composition having the formula Mo
3
S
k
L
n
Q
z
, wherein L represents independently selected ligands, n varies from 1 to 4, k varies from 4 through 7, Q is selected from the group consisting of neutral electron donating compounds including water, amines, alcohols, phosphines, and ethers, and z ranges from 0 to 5.
DETAILED DESCRIPTION OF THE INVENTION
The lubricant compositions of the present invention include a major amount of oil of lubricating viscosity. This oil may be selected from vegetable, animal, mineral, or synthetic oils. The oils may range in viscosity from light distillate mineral oils to heavy lubricating oils such as gas engine oil, mineral lubricating oil, motor vehicle oil, and heavy duty diesel oil. The oils may be unrefined, refined, and re-refined.
In general, the viscosity of the oil will range from about 2 centistokes to about 30 centistokes and especially in the range of 5 centistokes to 20 centistokes at 100° C.
The lubricant compositions of the present invention include a minor amount of a compound selected from compounds having the formula Mo
3
S
k
L
n
Q
z
and mixtures thereof wherein the L are independently selected ligands having organo groups with a sufficient 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, X
1
, X
2
, and Y are independently selected from the group of oxygen and sulfur, and wherein R
1
, R
2
, 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 remaider of the ligand and is predominantly hydrocarbyl in character within the context of this invention. Such substituents include the following:
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 fluoro, 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 o
Coyle Catherine Louise
Francisco Manuel A.
Guzi Peter John
Leta Daniel Paul
McConnachie Jonathan M.
Infineum USA L.P.
Johnson Jerry D.
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