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
1999-06-17
2001-04-03
McAvoy, Ellen M. (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...
C508S368000, C508S383000
Reexamination Certificate
active
06211123
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to lubricating oil compositions and concentrates therefor containing tungsten compounds and methods of making them.
BACKGROUND OF THE INVENTION
Molybdenum sulfur-containing compounds have been proposed and investigated as lubricant additives. U.S. Pat. Nos. 2,951,040; 3,419,589; 3,840,463; 4,966,719; 4,995,996; and 4,978,464 are representative of patent specifications describing both molybdenum and sulfur.
Molybdenum compounds for use as lubricant additives described in the art are principally dinuclear molybdenum compounds, characterised by the oxidation state Mo(V). However, International Patent Application No. PCT/IB97/01656 describes use of trinuclear molybdenum compounds as lubricant additives, i.e. characterised by a different oxidation state (Mo(IV); trinuclear molybdenum compounds have improved properties as lubricating additives compared with dinuclear molybdenum compounds as evidenced by test results in the above International Patent application, thus ameliorating the problem of providing improved lubricant performance in response to demands from original equipment manufacturers (OEM's).
The present invention provides tungsten analogues of the aforementioned trinuclear molybdenum compounds that are useful as additives in lubricating oil compositions.
SUMMARY OF THE INVENTION
In a first aspect, the invention is a lubricating oil composition comprising, or made by mixing, a major amount of an oil of lubricating viscosity and a minor amount of, as an additive, at least one compound comprising a trinuclear tungsten core and bonded thereto a ligand or ligands capable of rendering the compound oil-soluble or oil-dispersible. Preferably, the core, e.g. as a cluster, contains non-metallic atoms consisting wholly or partly of sulfur and more preferably it consists of trinuclear tungsten and sulfur. The additive may be in the form of mixtures of such compounds.
The compound may provide at least 1, for example 1 to 2,000, such as 5 to 1,000, preferably 20 to 1,000, ppm by mass of the tungsten, expressed as tungsten atoms, based on the mass of the composition.
The lubricating oil compositions according to the first aspect of the invention may have excellent antiwear, antioxidant, and friction-reducing properties; also they may be compatible with other additives used in formulating commercial lubricating oil compositions and can be made from readily available starting materials.
In a second aspect, the invention is an additive concentrate for blending with an oil of lubricating viscosity comprising, or made by mixing, an oleaginous carrier and from 1 to 200,000, for example 50 to 150,00 such as 50 to 100,000, ppm by mass of the tungsten, expressed as tungsten atoms, of an additive defined in the first aspect of the invention, based on the mass of the concentrate.
In a third aspect, the invention is a compound having the formula W
3
S
k
L
n
Q
z
wherein L represents a ligand or independently selected ligands, n is from 1 to 4, k is at least 4, for example from 4 to 10, such as 4 to 7, Q is a neutral electron donating compound, and z ranges from 0 to 5, wherein the compound has a core having the structure
In a fourth aspect, the invention is a method of lubricating an internal combustion engine comprising operating the engine and lubricating the engine with a lubricating oil composition of the first aspect of the invention.
In a fifth aspect, the invention is use of an additive as defined in the first aspect of the invention for enhancing one or more lubricating oil properties of a lubricating oil composition.
In a sixth aspect, the invention is a method for preparing a compound comprising a trinuclear thiotungsten core and bonded thereto a ligand or ligands capable of rendering the compound oil-soluble or oil-dispersible, which method comprises reacting a trinuclear thiotungsten source and a source of said ligand or ligands, to form said compound. The thiotungsten source may, for example, be a compound containing the [W
3
S
4
or
7
X
6
]
2−
ion where X represents halogen such as chlorine or bromine.
In a seventh aspect, the invention is a method of preparing a lubricating oil composition or an additive concentrate comprising mixing an additive defined in the first aspect of the invention with an oil of lubricating viscosity or an oleaginous carrier.
In particular, use, at least partly, may be made of the processes described by V. P. Fedin et al in Polyhedron, II, (24), 3159 (1992) and in Inorg. Chim. Acta, 18781 (1991). For example, the compound containing the [W
3
S
7
X
6
]
2−
ion, where the cation may be a quaternary ammonium ion, may be reacted with an alkali metal compound of the ligand. Such ion-containing compound may be made from the compound W
3
S
7
X
4
by reacting it with a quaternary ammonium halide/hydrogen halide mixture. Alternatively, the trinuclear tungsten compounds may be made directly from the compound W
3
S
7
X
4
by reacting with a phosphonium halide and then an alkali metal compound of the ligand.
The compound W
3
S
7
X
4
may be made by reacting tungsten, sulphur and a halogen, or by reacting a tungsten sulphide (e.g. WS
3
) and a phosphorus halide, both under conditions of high temperature,
Furthermore, use may be made of the process described by Shibahara T et al in Inorg. Chem. 1992, 31, 640-647 which, in particular, describes making the trinuclear tungsten aquo complex cation, [W
3
S
4
(H
2
O)
9
]
4+
. Most members of the series, [W
3
O
x
S
4-x
(H
2
O)
9
]
4+
where x is from 0 to 4, may be similarly synthesised. The ligands of the invention, e.g. dithiocarbamate (“dtc”), are combined with these cations, eg by reacting with dithiocarbamic acid (e.g. 4.4 moles) in the presence of sodium hydroxide to form compounds used in the invention.
Additionally, use may be made of the process described by Shibahara T et al in Inorg. Chem. 1994, 33, 292-301 to prepare compounds comprising a mixed metal trinuclear molybdenum/tungsten core, which compounds are within the scope of the present invention. Thus, there is described making the aquo complex cations, [MoW
2
S
4
(H
2
O)
9
]
4+
and [Mo
2
WS
4
(H
2
O)
9
]
4+
, which are combined with the ligands of the present invention, eg “dtc”, by reacting with dithiocarbamic acid (eg 4.4 moles) to form compounds useful in the present invention.
In this specification:
“comprising” or any cognate word is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof;
“major amount” means in excess of 50 mass % of the composition;
“minor amount” means less than 50 mass % of the composition, both in respect of the stated additive and in respect of the total mass % of all of the additives present in the composition, reckoned as active ingredient of the additive or additives;
the invention also provides the product obtained or obtainable as a result of any reaction between the various additive components of the composition or concentrates, essential as well as customary and optimal, under the conditions of formulation, storage or use;
“oil-soluble” or “dispersible” used herein do not necessarily indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. These do mean, however, that they are, for instance, soluble or stably dispersible in oil to an extent sufficient 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.
DETAILED DESCRIPTION OF THE INVENTION
Oil of Lubricating Composition
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 o
Bell Ian A. W.
Brown Alisdair J.
Cleverley John A.
Gomes Jose M. G.
McConnachie Jonathan M.
Infineum USA L.P.
McAvoy Ellen M.
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