Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting a...
Reexamination Certificate
2002-04-05
2003-03-18
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting a...
C508S291000, C508S442000, C508S554000
Reexamination Certificate
active
06534451
ABSTRACT:
This invention relates to a composition and a method of improving the extreme pressure lubrication characteristics of a power transmission fluid without sacrificing the oxidation resistance of the fluid.
The continuing quest for improved vehicle fuel economy forces manufacturers to make transmissions smaller, thereby lighter, and utilize them in less ventilated environments. The consequences of these designs are that transmission power throughput is increased, loads on gear surfaces are increased, energy dissipation in the transmission increases while airflow around the transmission decreases due to aerodynamic improvements to the vehicle that reduce convective cooling. Smaller transmissions mean smaller lubricant volumes are required to handle the cooling of the transmission. The net result of these factors is that the demands on the lubricant become very severe. Higher power throughputs, at higher torque levels, increase the needs for excellent extreme pressure characteristics in the lubricant. Reduced cooling with higher transmission energy losses and reduced fluid volume, means higher lubricant temperatures and increased need for oxidation resistance of the fluid and additives.
One solution to this problem is to produce additives with enhanced extreme pressure lubrication characteristics. The problem is more complicated, however, in that in the situation described above oxidation resistance is also a critical aspect of the fluid performance. Therefore, any new extreme pressure agents must also possess excellent oxidation resistance. This has classically presented a problem to lubricant formulators since most extreme pressure agents contain large amounts of sulfur and/or phosphorus; elements that are associated with poor resistance to oxidation.
We have found a class of materials, produced by direct sulfurization of dialkylphosphites followed by neutralization with certain polyamine-containing species, that significantly improve the extreme pressure characteristics of lubricants in which they are used, while having no deleterious effects on the oxidation resistance of the lubricant.
For the purposes of this invention a power transmission fluid is defined as any lubricant used in contact with gears involved in the transmission of mechanical energy. Commonly these devices would include, but not be limited to, automatic transmissions, manual transmissions, continuously variable transmissions, automated manual transmissions, transfer cases, axles and differentials used in mobile applications. They would also include fluids used in conjunction with stationary gearing used in industrial applications and industrial transmissions as well as hydraulic fluids.
In accordance with this invention, there has been discovered a power transmission fluid which exhibits improved antiwear properties comprising a major amount of an oil of lubricating viscosity containing effective amounts of:
(a) an ashless dispersant;
(b) a friction modifier;
(c) an antioxidant;
(d) a viscosity modifier; and
(e) an antiwear agent which is the product formed by reacting elemental sulfur and a dialkyl phosphite of the formula R
1
OR
2
OPOH, where R
1
and R
2
may be alkyl of 1 to 18 carbon atoms, at a temperature of 45-75° C., in the presence of an acylated amine compound selected from the group consisting of:
wherein R
1
and R
2
in Structure A can be the same or different hydrocarbyl group from 4 to 200 carbon atoms, branched or linear alkyl or alkenyl, such as polyisobutenyl, preferably polyisobutenyl of Mn 300-2500 or C
12
-C
20
alkenyl, and z is an integer from 1 to 8, and
wherein R
3
and R
4
are the same or different alkyl groups of from 4 to 30 carbon atoms each, branched or linear, and z is an integer from 1 to 8, with the proviso that said antiwear agent provides to the composition 5 to 5000 ppm sulfur and 5 to 5000 ppm phosphorus.
Further embodiments of this invention are the thiophosphite antiwear agent itself and a power transmitting apparatus, such as the devices listed above, containing the fluid of this invention.
Lubricating oils useful in this invention are derived from natural lubricating oils, synthetic lubricating oils, and mixtures thereof. In general, both the natural and synthetic lubricating oil will each have a kinematic viscosity ranging from about 1 to about 100 mm
2
/s (cSt) at 100° C., although typical applications will require the lubricating oil or lubricating oil mixture to have a viscosity ranging from about 2 to about 8 mm
2
/s (cSt) at 100° C.
Natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale. The preferred natural lubricating oil is mineral oil.
Suitable mineral oils include all common mineral oil basestocks. This includes oils that are naphthenic or paraffinic in chemical structure. Oils that are refined by conventional methodology using acid, alkali, and clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents such as phenol, sulfur dioxide, furfural, dichlorodiethyl ether, etc. They may be hydrotreated or hydrofined, dewaxed by chilling or catalytic dewaxing processes, or hydrocracked. The mineral oil may be produced from natural crude sources or be composed of isomerized wax materials or residues of other refining processes.
Typically the mineral oils will have Kinematic viscosities of from 2.0 mm
2
/s (cSt) to 8.0 mm
2
/s (cSt) at 100° C. The preferred mineral oils have Kinematic viscosities of from 2 to 6 mm
2
/s (cSt), and most preferred are those mineral oils with viscosities of 3 to 5 mm
2
/s (cSt) at 100° C.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as oligomerized, polymerized, and interpolymerized olefins [e.g., polybutylenes, polypropylenes, propylene, isobutylene copolymers, chlorinated polylactenes, poly(1-hexenes), poly(1-octenes), poly-(1-decenes), etc., and mixtures thereof]; alkylbenzenes [e.g., dodecyl-benzenes, tetradecylbenzenes, dinonyl-benzenes, di(2-ethylhexyl)benzene, etc.]; polyphenyls [e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.]; and alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs thereof, and the like. The preferred oils from this class of synthetic oils are oligomers of &agr;-olefins, particularly oligomers of 1-decene.
Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc. This class of synthetic oils is exemplified by: polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide; the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of polypropylene glycol having a molecular weight of 1000 to 1500); and mono- and poly-carboxylic esters thereof (e.g., the acetic acid esters, mixed C
3
-C
8
fatty acid esters, and C
12
oxo acid diester of tetraethylene glycol).
Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoethers, propylene glycol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebasic acid with t
Gorda Keith R.
Nibert Roger K.
Watts Raymond F.
Howard Jacqueline V.
Infineum International Ltd.
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