Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2001-11-29
2004-06-29
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S322000, C508S342000, C508S502000
Reexamination Certificate
active
06756348
ABSTRACT:
BACKGROUND
This invention relates to an antioxidant system and lubricating oil comprising the antioxidant system. The lubricating oil of this invention may be used as a lubricant for any lubricating application, however its enhanced properties makes it particularly applicable for use as a lubricant for natural gas fueled engines.
Natural gas fueled engines are engines that use natural gas as a fuel source. Lubricating oil with high resistance to oxidation, nitration and viscosity increase is preferred for lubricating oils used in natural gas engines because of the conditions related to this type of engine.
Natural gas has a higher specific heat content than liquid hydrocarbon fuels and therefore it burns hotter than liquid hydrocarbon fuels under typical conditions. In addition, since it is already a gas, natural gas does not cool the intake air by evaporation as liquid hydrocarbon fuel droplets do. Furthermore, many natural gas fueled engines are run either at or near stoichiometric conditions, where less excess air is available to dilute and cool combustion gases. As a result, natural gas fueled engines generate higher combustion gas temperatures than engines burning liquid hydrocarbon fuels. Since the rate of formation of NO
x
increases exponentially with temperature, natural gas fueled engines may generate NO
x
concentrations high enough to cause severe nitration of lubricating oil.
In most cases, natural gas fueled engines are used continuously at 70 to 100% load, whereas an engine operating in vehicular service may only spend 50% of its time at full load. Lubricating oil drain intervals may vary in vehicular service, but are typically shorter than those for natural gas fueled engines.
Natural gas fueled engines may be located in remote areas where service is not readily available and may be expensive. Because of this it is important to ensure the reliability of natural gas fueled engines. High resistance to oxidation and nitration is therefore required for lubricating oils used in natural gas engines.
Good valve wear control is important for keeping engine operating costs down and may be achieved by providing the proper amount and composition of ash. Minimizing combustion chamber deposits and spark plug fouling are also considerations in setting the ash content and composition in these oils. Lubricating oil ash levels are limited, so detergents must be carefully selected to minimize piston deposits and ring sticking. Good wear protection is required to prevent scuffing and corrosion.
If lubricating oils for natural gas fueled engines are not formulated to handle typical environments for those engines, the lubricating oil will deteriorate rapidly during use. This deterioration will typically cause the lubricating oil to thicken which results in engine sludge, piston deposits, oil filter plugging, and in severe cases, accelerated ring and liner wear.
The general industry approach to reduce deterioration of lubricating oil and the resultant engine sludge, piston deposits, oil filter plugging and accelerated ring and liner wear is to add antioxidants such as hindered phenols as well as diphenyl amines and sulfurized compounds. Increasing the amount of these antioxidants in lubricating oil is increasingly effective to avoid lubricating oil deterioration. But at some point the solubility limit of the additive reaches maximum effectiveness and detrimental effects can be also noticed in piston deposit control.
While it is no surprise that increasing the amount of antioxidant is effective in increasing the antioxidant properties of a finished oil, the antioxidant system of this invention provides a method to enhance the antioxidant properties without increasing the amount of antioxidant. This method involves use of an antioxidant system that comprises sulfurized isobutylene and an antioxidant system that comprises sulfurized isobutylene and hindered phenol.
SUMMARY
One embodiment of this invention comprises an antioxidant system comprising sulfurized isobutylene. Another embodiment of this invention comprises an antioxidant system comprising sulfurized isobutylene and one or more hindered phenols. The hindered phenols of this antioxidant system may comprise butylated hydroxy toluene (BHT), 3,5-di-t-butyl 4-hydroxy phenol propionate and one or more antioxidants have the general formula:
wherein R is a C
7
to C
9
alkyl group.
Another embodiment of this invention is an additive formulation comprising one or more of the additive systems of this invention and other additives.
The lubricating oil of this invention may comprise base oil and one or more of the additive formulations of this invention. The lubricating oil of this invention may comprise base oil and one or more of the additive systems of this invention. One embodiment of this invention may comprise a method of lubricating engines comprising contacting one or more of the lubricating oils of this invention with one or more engines. One embodiment of this invention may comprise a method of lubricating natural gas fueled engines comprising contacting one or more of the lubricating oils of this invention with one or more natural gas fueled engines. This invention comprises methods for making any embodiments of the lubricating oil or additive systems or additive formulations of this invention comprising combining the components in any order at a temperature sufficient to encourage mixing of the components, but not sufficient to degrade the components. This invention comprises methods for making any embodiments of the lubricating oil of this invention comprising combining the components in any order at a temperature of about 140 degrees F.
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed to one or more antioxidant systems for use in lubricating oils. One embodiment of the invention may be lubricating oil that comprises sulfurized isobutylene as an antioxidant. Another embodiment of the invention may be an additive formulation that comprises sulfurized isobutylene as an antioxidant, and one or more dispersants, one or more detergents, and one or more wear inhibitors. Another embodiment of this invention may be lubricating oil comprising one or more of the antioxidant systems of this invention. Another embodiment of this invention may be a lubricating oil comprising one or more of the additive formulations of this invention. These antioxidant systems, additive formulations and lubricating oils may be particularly useful in natural gas fueled engines.
Another embodiment of the invention may be lubricating oil that comprises sulfurized isobutylene in combination with an antioxidant such as hindered phenol. One embodiment of the invention may be an additive formulation that comprises sulfurized isobutylene, an antioxidant such as hindered phenol, and one or more dispersants, one or more detergents, and one or more wear inhibitors. Another embodiment of this invention may be lubricating oil comprising one or more of the antioxidant systems of this invention. Another embodiment of this invention may be lubricating oil comprising one or more of the additive formulations of this invention. These antioxidant systems, additive formulations and lubricating oils may be particularly useful in natural gas fueled engines.
Another embodiment of this invention may be a method to make a lubricating oil comprising the antioxidant systems of this invention by combining the components and mixing them together and heating at a temperature sufficient to encourage mixing of the components, but not sufficient to degrade the components. Another embodiment of this invention is a method of using the lubricating oils of this invention to lubricate an engine by contacting the engine with the lubricating oil of this invention. Another embodiment of this invention is a method of using the lubricating oils of this invention to lubricate a natural gas engine by contacting a natural gas engine with the lubricating oil of this invention.
I. Antioxidant System
One embodiment of the antioxidant system of this invention may comprise sulfurized isob
Logan Mark R.
Palazzotto John D.
Chevron Oronite Company LLC
Fallon Martin
Howard Jacqueline V.
Jones Josetta
Stokley Linda
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