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
2003-11-04
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
C508S415000, C508S519000, C508S584000
Reexamination Certificate
active
06642191
ABSTRACT:
BACKGROUND
This invention relates to lubricating oil comprising a combination of a hindered phenol and Group II, III and IV base oil. The lubricating oil of this invention may be used in any manner, however its enhanced properties make it particularly applicable for use in engines fueled by natural gas.
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 intake air by evaporation as liquid hydrocarbon fuel droplets do. Furthermore, many natural gas fueled engines are run either at or near stoichiometric conditions, at which 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.
It is important to ensure the reliability of natural gas fueled engines because natural gas fueled engines may be located in remote areas where service is not readily available. Lubricating oil used in natural gas engines therefore requires high resistance to oxidation and nitration.
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 additional antioxidant reaches maximum effectiveness and at times further addition of antioxidant may even detrimentally affect piston deposit control.
While it is no surprise that increasing the amount of antioxidant is effective in increasing the life of lubricating oil, this invention provides a method to increase the life of lubricating oil with out necessarily increasing the amount of antioxidant.
SUMMARY
The lubricating oil of this invention may comprise a minor amount of one or more hindered phenols of the general formula:
and a major amount of at least one of Group II, III and IV base oils. More specifically, the lubricating oil of this invention may comprise about 0.20 wt. % to about 3 wt. % of one or more hindered phenols having this general formula. Liquid hindered phenols are preferred. One embodiment of the lubricating oil of this invention may comprise one or more molybdenum oxidation sulfide inhibitors in an amount no more than 0.5% wt. Unless otherwise specified the term “wt. %” as used herein means wt. % of lubricating oil. One embodiment of this invention comprises a lubricating oil of claim
1
having a total base number of about 2.15 milligrams Potassium Hydroxide per gram of sample (mg KOH/gr) to about 8.88 mg KOH/gr as determined by ASTM D 2896. One embodiment of this invention comprises a lubricating oil having a total ash content of about 0.10 wt. % to about 1.50 wt. % as determined by ASTM D874. Lubricating oil of this invention may have less than 4000 ppm sulfur. One embodiment of this invention comprises combining the hindered phenol of the invention with the base oil in any order and mixing. Another embodiment of this invention comprises a method of lubricating engines comprising contacting one or more engines with the lubricating oil of this invention. Lubricating oil of this invention may comprise a major amount of at least one of Group II, III and IV base oil and a minor amount of 3,5-di-t-butyl 4-hydroxy phenol propionate. Lubricating oil of this invention may comprise about 0.20 wt. % to about 3 wt. % 3,5-di-t-butyl 4-hydroxy phenol propionate, preferably about 0.6 wt % to about 2.5 wt. %. The 3,5-di-t-butyl 4-hydroxy phenol propionate may be liquid. One embodiment of this invention may comprise an additive formulation comprising 3,5-di-t-butyl 4-hydroxy phenol propionate; one or more dispersants; one or more wear inhibitors; and one or more detergents. Lubricating oil of this invention may comprise about 1 wt. % to about 8 wt. % of one or more dispersants, about 1 wt. % to about 8.5 wt. % of one or more detergents, about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors, about 0.5 wt. % to about 3 wt. % 3,5-di-t-butyl 4-hydroxy phenol propionate, and about 40 wt. % to about 97 wt. % of at least one of Group II, III and IV base oil or preferably about 80 wt. % to about 97 wt. % of at least one of Group II, III and IV base oil or more preferably about 60 wt. % to about 97 wt. % of at least one of Group I, III and IV base oil. Lubricating oil of this invention may comprise about 1.25 wt. % to about 6 wt. % of one or more dispersants; about 2 wt. % to about 6 wt. % of one or more detergents; about 0.3 wt. % to about 0.8 wt. % of one or more wear inhibitors, about 0.6 to about 2.5 wt. % 3,5-di-t-butyl 4-hydroxy phenol propionate and about 40 wt. % to about 97 wt. % of at least one of Group II, III and IV base oil or preferably about 80 wt. % to about 97 wt. % of at least one of Group II, III and IV base oil or more preferably about 60 wt. % to about 97 wt. % of at least one of Group II, III and IV base oil.
DETAILED DESCRIPTION OF THE INVENTION
This invention provides lubricating oil that may be used in any engine, but that has exhibited a surprisingly long life when tested in a natural gas fueled engine.
The lubricating oil of this invention may comprise one or more of the hindered phenols described herein and Group II, III and IV base oils. A preferred lubricating oil of this invention comprises a major amount of one or more base oils from Groups II through IV and a minor amount of the hindered phenols described herein. The term “major amount” when used herein means more than 40 wt. %. The term “minor amount” when used herein means less than 20 wt. %.
One embodiment of this invention comprises an additive formulation comprising one or more of the hindered phenols described herein, one or more dispersants, one or more detergents and one or more wear inhibitors.
A preferred lubricating oil of this invention may comprise a major amount of base oils from Group II through Group IV, a minor amount of one or more of the additive formulations comprising the hindered phenols described herein, one or more detergents, one or more dispersants and one or more wear inhibitors.
Another embodiment of this invention comprises lubricating oils comprising additive formulations comprising the hindered phenols described herein.
Preferred lubricating oil of this invention may comprise the hindered phenols described herein and Group II through IV base oils in a formulation that has about 0.10 wt. %
Logan Mark R.
Palazzotto John D.
Chevron Oronite Company LLC
Fallon Martin C.
Howard Jacqueline V.
Jones Josetta
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