Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
2002-08-01
2004-02-24
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S291000, C508S232000, C508S375000, C508S376000, C508S377000
Reexamination Certificate
active
06696393
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed, in part, to lubricant compositions for reducing wear in internal combustion engines lubricated with a low phosphorus content lubricating oil, and to methods employing such. The lubricant compositions of this invention comprise a synergistic combination of a complex of a molybdenum
itrogen containing compound and at least one oil-soluble, phosphorus-containing, anti-wear compound wherein the total phosphorus employed in the composition is no more than about 0.06 weight percent based on the total weight of the composition.
REFERENCES
The following references are cited in this application as superscript numbers:
1
Buckley, III, Long Chain Aliphatic Hydrocarbyl Amine Additives Having an Oxyalkylene Hydroxy Connecting Group, U.S. Pat. No. 4,975,096, issued Dec. 4, 1990
2
Buckley, Methods and Compositions for Preventing the Precipitation of Zinc Dialkyldithiophosphates Which Contain High Percentages of a Lower Alkyl Group, U.S. Pat. No. 4,495,075, issued Jan. 22, 1985
3
Beck, et al., Impact of Oil-Derived Catalyst Poisons on FTP Performance of LEV Catalyst Systems, SAE Technical Paper 972842 (1997)
4
Johnson, et al., Effects of Oil-Derived Contaminants on Emissions from TWC-Equipped Vehicles, SAE 200-01-1881 (2000)
All of the above references are herein incorporated by reference in their entirety to the same extent as if each individual reference was specifically and individually indicated to be incorporated by reference in its entirety.
STATE OF THE ART
Emissions arising from automotive exhaust has been a problem for several decades and approaches for addressing this problem have included the use of unleaded fuel (to deal, in part, with lead pollution arising from leaded fuels), oxygenated fuel (to reduce hydrocarbon emissions), the use of catalytic converters (also to reduce hydrocarbon emissions), etc.
Catalytic converters are now universally employed with gasoline powered vehicles and the efficiency of these converters is directly related to the ability of the catalyst to effect conversion of unburnt or partially burnt hydrocarbons generated during combustion to carbon dioxide and water. One problem arising with the use of such converters is poisoning of the catalyst resulting in reduced catalyst efficiency. Since catalytic converters are intended for extended use, catalyst poisoning results in higher levels of atmospheric discharges of pollutants from internal combustion engines over prolonged periods of time.
In order to minimize such poisoning, the industry has set standards for both fuel and lubricant contents. For example, standards for fuels have included the use of unleaded gasoline in order to avoid lead poisoning of the catalyst
1
as well as lead discharge into the environment.
As to the lubricants, one additive family currently being addressed by industry standards is the phosphorus-containing additives used in lubricant compositions employed to lubricate internal combustion engines. Specifically, phosphorus-containing additives reach the catalytic converter as a result of, for example, exhaust gas recirculation and/or oil blow-by processes as well as other methods known in the art. See, for example, Beck, et al. and Johnson, et al.
3.4
In any event, the phosphorus is known to accumulate in the catalytic converter, at active metal sites; thus reducing catalyst efficiency and effectively over time, poisoning the catalyst. As a result of the above, a new focus is to lower phosphorus in the lubricating oils. For example, the draft GF-4 specifications for lubricant compositions have proposed significantly lower phosphorus contents than heretofore employed.
A problem arises when the level of phosphorus is reduced in a lubricant composition containing an oil-soluble, phosphorus-containing, anti-wear compound in that there is a significant reduction in anti-wear performance arising from this diminution in phosphorus content. One well known class of antiwear additives are metal alkylphosphates, especially zinc dialkyl dithiophosphates are generally employed in lubricating oils at phosphorous levels above 0.1 weight percent when used for wear control. At lower levels, it is not found to be an effective antiwear additive. For instance, as exemplified herein, lowering the level of phosphorus due to the presence of a metal dithiophosphate additive in a lubricant composition by one-half from 0.095 weight percent to 0.048 weight percent phosphorus results in about a seven-fold increase in engine wear.
This invention is directed to the discovery that lubricant compositions comprising a combination of a complex of a molybdenum
itrogen-containing compound and low levels of one or more oil-soluble, phosphorus-containing, anti-wear compounds synergistically reduce wear levels when used to lubricate gasoline engines.
With regard to the above, both metal dihydrocarbyl dithiophosphates, also referred to herein as metal dithiophosphates, and molybdenum
itrogen containing complexes, including the preferred molybdenum succinimide complexes are well known in the art. In addition, lubricant compositions comprising combinations of alkyl or alkenyl succinimides and zinc dialkyl dithiophosphate are disclosed, for example, by Buckley.
2
Still further, lubricant compositions comprising both molybdenum succinimide and zinc dialkyl dithiophosphate and having a total phosphorus content of at least 0.07 weight percent based on the total weight of the composition have been hereto commercialized.
SUMMARY OF THE INVENTION
As noted above, this invention is directed, in part, to lubricant compositions comprising a combination of a complex of a molybdenum
itrogen-containing compound and at least one oil-soluble, phosphorus-containing anti-wear compound wherein the total phosphorus employed in the composition is no more than about 0.06 weight percent based on the total weight of the composition. This combination of additives synergistically reduces wear levels when used in lubricant compositions to lubricate internal combustion engines.
Accordingly, in one of its composition aspects, this invention is directed to a lubricating oil composition comprising a major amount of an oil of lubricating viscosity,
at least one oil-soluble, phosphorus-containing, anti-wear compound wherein the weight percent of total phosphorus in the composition is no more than about 0.06 weight percent based on the total weight of the composition; and
an anti-wear effective amount of a complex of a molybdenum
itrogen containing compound.
In a preferred embodiment, the total phosphorus in the composition is no more than 0.05 weight percent based on the total weight of the composition.
Preferably, the oil-soluble, phosphorus-containing, anti-wear compound is selected from the group consisting of metal dithiophosphates, phosphorus esters (including phosphates, phosphonates, phosphinates, phosphine oxides, phosphites, phosphonites, phosphinites, phosphines and the like), amine phosphates and amine phosphinates, sulfur-containing phosphorus esters including phosphoro monothionate and phosphoro dithionates, phosphoramides, phosphonamides and the like. More preferably, the phosphorus-containing compound is a metal dithiophosphate and, even more preferably, a zinc dithiophosphate.
The complex of a molybdenum
itrogen-containing compound is preferably a molybdenum succinimide. The complex includes both sulfurized and non-sulfurized forms and, preferably, the complex is sulfurized.
A particularly preferred complex of a molybdenum
itrogen containing compound is disclosed in commonly assigned U.S. Ser. No. 10/159,446 filed on May 31, 2002 as and entitled “Reduced Color Molybdenum-Containing Composition and a Method of Making Same” which application is incorporated herein by reference in its entirety.
In one of its method aspects, this invention is directed to a method for controlling wear during operation of an internal combustion engine, which method comprises operating the engine with a lubricant composition comprising a major amount of an oil of lubricating viscosity, at least one o
Caroli Claude J.
Chevron Oronite Company LLC
Foley Joseph P.
Howard Jacqueline V.
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