Chemistry of hydrocarbon compounds – Product blend – e.g. – composition – etc. – or blending process...
Reexamination Certificate
2000-02-08
2001-07-03
Howard, Jacqueline V. (Department: 1764)
Chemistry of hydrocarbon compounds
Product blend, e.g., composition, etc., or blending process...
C585S007000, C585S302000, C508S110000
Reexamination Certificate
active
06255546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to functional fluids having low Brookfield Viscosities comprising a mixture of base stocks and containing performance additives.
2. Description of the Related Art
Functional fluids comprise a broad range of lubricants that are used in automotive and industrial hydraulic systems, automotive transmissions, power steering systems, shock absorber fluids, and the like. These fluids transmit and control power in mechanical systems, and thus must have carefully controlled viscometric characteristics. In addition, these fluids may sometimes be formulated to provide multigrade performance so as to ensure year round operation in variable climates. Among the most important requirements for a functional fluid is low temperature fluidity, which can be measured by, for example, the Brookfield viscometer.
Automatic transmission fluids are one of the most common functional fluids, and an integral part of all automatic transmissions. Automatic transmissions are used in about 80% to 90% of all vehicles in North America and Japan and their use is becoming more commonplace in other parts of the world. They are the most complex and costly sub-assemblies of a vehicle and the major OEMs have stringent specifications to control all aspects of the components that go into their manufacture.
An automatic transmission comprises a torque converter, planetary gears, output drives and hydraulic system. The ATF acts as a hydraulic fluid to transfer power in the torque converter and to actuate complex controls to engage the gears to give the correct vehicle speed. The fluid must have the right viscometrics at ambient start-up temperatures, while maintaining sufficient viscosity at higher operating temperatures. ATF must also be very oxidation stable because it is subjected to high temperatures and is expected to remain in service for up to 100,000 miles in some cases.
Whereas in the past automatic transmission fluids generally used solvent neutral base stocks, and their use is still common in some applications, over the past few years, with the increasing performance demands being made on automatic transmission fluids, the use of hydrocracked base stocks have become more widespread. These base stocks tend to give improved low temperature performance and longer oxidation life.
It has now been found that particular blends of hydrocracked base stocks, which may also contain some minor amount of solvent neutral base stocks, give excellent low temperature Brookfield performance.
DESCRIPTION OF THE INVENTION
The present invention is directed to a functional fluid comprising:
(A) a mixture of at least two hydrocracked base stocks, said mixture comprising
(i) at least one first hydrocracked base having a kinematic viscosity of about 3.5 to about 6.5 mm
2
/sec at 100° C., a viscosity index of about 100 to about 120, a pour point of about −12° C. maximum, an aniline point of about 100° C. to about 120° C., a saturates content of about 92 to about 99 mass %;
(ii) at least one second hydrocracked base stock having a kinematic viscosity of about 1.5 to about 3.5 mm
2
/sec at 100° C., a viscosity index of about 90 or higher, a pour point of about −30° C. maximum, an aniline point of about 95° C. to about 110° C., a saturates content of about 90 to about 99 mass %;
said first and second hydrocracked base stocks being mixed in an amount of about 60 to about 90 vol % of the first hydrocracked base stock (i) and about 10 to about 40 vol % of the second hydrocracked base stock (ii), based on hydrocracked stock;
wherein the first hydrocracked base stock (i) and second hydrocracked base stock (ii) are not the same; and
(B) zero up to about 45 vol % of one or more conventional solvent neutral base stock(s), the conventional solvent neutral base stock(s) having a kinematic viscosity of about 2.5 to about 5.5 mm
2
/sec at 100° C., a viscosity index of about 90 to about 105, a pour point of about −12° C. maximum, an aniline point of about 95° C. to about 105° C., a saturates content of about 75 to about 85 mass %; wherein
said mixture of base stocks has a kinematic viscosity of about 3.7 to about 5 mm
2
/sec at 100° C., a viscosity index of about 100 to about 115, a pour point of about −24° C. maximum;
(C) an additive package, the resulting additized functional fluid having, a kinematic viscosity of about 6.8 to about 8.0 mm
2
/sec at 100° C., a viscosity index of about 150 to about 200, a pour point of about <−42° C. maximum, and a Brookfield viscosity of about 15,000 cP or less at −40° C.
The hydrocracked base stocks may be prepared by use of any of the hydrocracking process procedures currently used in the art, as well as any processes yet to be developed. It is believed the performance and function of the hydrocracked base stocks in the present invention are independent of the particular procedural techniques employed in the production of the base stocks. Typically hydrocracked base stocks are made starting with distillate from the atmosphere/vacuum pipestills and/or coker distillate, optionally subjecting such distillate to an aromatics removal step using an aromatics selective solvent such as phenol, furfural, NMP, etc. The distillate is then subjected to hydroconversion in at least one hydroconversion zone, more typically two zones whereas the distillate is exposed to a catalyst in the presence of hydrogen at high temperature and pressure to effect the saturation of aromatics, open rings and reduce sulfur and nitrogen content.
If the previously recited, optional aromatics removal step was not produced, the stream from the hydroconversion stage(s) can now be subject to an aromatics removal step such as solvent extraction employ a selective solvent such as phenol, furfural, NMP, etc. This stream can then be subjected to wax removal employing solvent dewaxing or catalytic dewaxing or isomerization. The stream, either before or after such dewaxing can also be subjected to hydro-finishing to further reduce the sulfur and nitrogen content.
Examples of suitable hydrocracking processes can be found in “All Hydroprocessing Route for High Viscosity Index Lubes” Zakarian et al Energy Progress, Vol. 7, No. 1, pp. 59-64; “Hydrotreated Lube Oil Base Stocks” Cashmore et al, SAE Paper 821235; “Lube Facility Makes High Quality Lube Oil from Low Quality Feed” Farrell et al, Oil and Gas Journal May 19, 1986, Technology, pp. 47-51; U.S. Pat. No. 5,976,353.
The first hydrocracked stock employed is one or more stocks having a kinematic viscosity of about 3.5 to about 6.5 mm
2
/s at 100° C., preferably about 3.8 to about 5 mm
2
/s at 100° C., more preferably about 4.2 to about 4.8 mm
2/
s at 100° C., a viscosity index in the range of about 100 to about 120, preferably about 105 to about 120, more preferably about 110 to about 120, a pour point of about −12° C., preferably about −15° C., more preferably about −18° C., an aniline point of about 100 to about 120° C., preferably about 105 to about 115° C., and a saturates content of about 92 to about 99 mass %, preferably about 93 to about 99 mass %, more preferably about 94 to about 96 mass %.
The second hydrocracked stock employed is one or more stocks having a kinematic viscosity of about 1.5 to about 3.5 mm
2
/s at 100° C., preferably about 2.0 to about 3.0 mm
2/
s at 100° C., a viscosity index of about 90 or higher, preferably about 90 to about 105, a pour point of about −30° C. maximum, an aniline point of about 95 to about 110° C., and a saturates content of about 90 to about 99 mass %, preferably about 95 mass % or higher, most preferably about 97 mass % or higher.
The first hydrocracked base stock is used in an amount in the range of about 60 to about 90 vol %/o, preferably about 65 to about 90 vol % and the second hydrocracked base stock is used in an amount in the range of about 10 to about 40 vol %, preferably about 10 to about 35 vol % based on the hydrocracked oil, provided that, if a solvent neutral base stock is present, the amount
Allocca Joseph J.
ExxonMobile Research and Engineering Company
Howard Jacqueline V.
LandOfFree
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