Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting an...
Reexamination Certificate
1997-04-22
2002-07-16
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting an...
C508S465000, C554S165000, C554S126000
Reexamination Certificate
active
06420322
ABSTRACT:
BACKGROUND OF THE INVENTION
Vegetable oils are obtainable in large volumes from renewable resources and in general are characterized as readily biodegradable or “environmentally friendly”. As a result, such oils and related materials are at least theoretically desirable for use in a wide variety of applications.
With respect to use for lubrication purposes, especially as machine lubricants, vegetable oils have not been fully desirable. Many vegetable oils do not possess the desired spectrum of characteristics relating to: viscosity index; pour point; oxidative stability; compatibility with additives; and, flash point/volatility among others.
Vegetable oils, such as a soybean oil (“SBO”), do however possess many desirable properties for use as a lubricant. In particular, SBO provides good boundary lubrication, good viscosity, high viscosity index and high flash point. In addition, SBO is nontoxic and readily biodegradable. For example, under standard test conditions (e.g., OCED 301D test method), SBO biodegrades up to 80% into carbon dioxide and water in 28 days, compared to 25% or less for typical petroleum-based lubricating fluids.
However, as exemplified by SBO, two characteristics, which are often major limitations for the utilization of vegetable oils as lubricants, relate to stability and low temperature behavior. In particular, vegetable oils such as SBO often contain substantial amounts of unsaturation (i.e., one or more carbon-carbon double bonds distributed along the fatty acyl chains). The sites of unsaturation may be associated with sufficient oxidative reactivity to render the oils insufficiently stable for use as lubricants. If efforts are made to reduce the unsaturation, for example by hydrogenation, generally undesirable changes in pour point and/or viscosity index result.
SUMMARY OF THE INVENTION
The present invention relates to unsaturated triacylglycerol oils, such as unsaturated vegetable oils. It particularly concerns modifications of selected vegetable oils to produce liquid products with preferred properties for use, for example as lubricant base stocks or in related uses. The unsaturated triacylglycerol oil is typically derived from plants, such as an oil seed, or an animal, such as tallow.
A process for modifying an unsaturated triacylglycerol oil, such as an unsaturated vegetable oil stock, to enhance its fluidity and/or oxidative stability is provided. The process includes (i) reacting the unsaturated triacylglycerol oil with an olefinic hydrocarbon to form a cycloaddition product and, optionally, (ii) at least partially hydrogenating the cycloaddition product to form a hydrogenated cycloaddition product. The cycloaddition product formed from the reaction with the olefinic hydrocarbon includes triacylglycerols which have at least one fatty acyl chain modified to include a cycloaddition adduct. If desired, either the cycloaddition product or the hydrogenated cycloaddition product may be fractionated using conventional techniques to alter the spectrum of modified and unmodifed triacylglycerols present. For example, the hydrogenated cycloaddition product may be fractionated to remove at least a portion of the saturated triacylglycerols, thereby enhancing the fluidity properties of the fractionated cycloaddition product with respect to the hydrogenated cycloaddition product.
Herein, when reference is made to the term “unsaturated triacylglycerol oil”, the intent is to refer to a material comprising triacylglycerols, whether altered or not, derived from various plant and animal sources, such as oil seed sources. The term at least includes within its scope: (a) such materials which have not been altered after isolation; (b) materials which have been refined, bleached and/or deodorized after isolation; (c) materials obtained by a process which includes fractionation of an unsaturated triacylglycerol oil; and, also, (d) oils obtained from plant or animal sources and altered in some manner, for example through partial hydrogenation. It will be understood that the unsaturated triacylglycerol oil may include a mixture of triacylglycerols, and a mixture of triacylglycerol isomers. By the term “triacylglycerol isomers”, reference is meant to triacylglycerols which, although including the same esterified acid residues, may vary with respect to the location of the residues in the triacylglycerol. For example, an unsaturated triacylglycerol oil such as a vegetable oil stock can include both symmetrical and unsymmetrical isomers of a triglyeride which includes two different fatty acyl chains (e.g., includes both stearate and oleate groups).
Herein, the result of adding an olefinic hydrocarbon to an unsaturated triacylglycerol oil, such as a vegetable oil stock, will be referenced as a “cycloaddition product.” The term “cycloaddition product” includes within its scope practices which involve adding one or more olefinic hydrocarbons (e.g., dienic and/or monoolefinic hydrocarbons), on an average per molecule basis, to the unsaturated triacylglycerol oil. As used herein, the term “cycloaddition adduct” refers to an adduct produced by the reaction of an olefinic hydrocarbon and a double bond in a fatty acyl chain of a triacylglycerol. One example of a cycloaddition adduct is the adduct produced by a Diels-Alder reaction between a dienic hydrocarbon and a double bond in a triacylglycerol fatty acyl chain. Of course, it will be understood that the cycloaddition of the olefinic hydrocarbon will not necessarily be uniform in the mixture, but rather the result of the cycloaddition may be cycloaddition to some triacylglycerol molecules, and not to others. Nor will the cycloaddition product necessarily include the formation of at least one (on an average molecular basis) cycloaddition adduct per triacylglycerol molecule. For example, the cycloaddition product will typically include a number of unmodified triacylglycerols, i.e., triacylglycerols with fatty acyl chains lacking a cycloaddition adduct.
The cycloaddition adducts and hydrogenated cycloaddition adducts have an oxidative stability (as evidenced by their AOM value and/or active methylene content) which is increased with respect to the oxidative stability of the unsaturated triacylglycerol oil. The pour point of the hydrogenated cycloaddition adduct is generally less than the pour point of a product obtained from hydrogenation of the the unsaturated triacylglycerol oil by a corresponding amount. In some instances, the pour point of a hydrogenated cycloaddition adduct may even be reduced with respect to the pour point of the corresponding unsaturated triacylglycerol oil. The present method typically reduces the active methylene content of the unsaturated triacylglycerol oil at least about 10% and preferably by at least about 25% with respect to that of the corresponding unsaturated triacylglycerol oil.
The olefinic hydrocarbons used to form the cycloaddition product may include a diene and/or a monoolefinic hydrocarbon. The diene can react with a double bond (“dienophile”) in a fatty acyl chain of a triacylglycerol molecule to form a 4+2 cycloadduct (Diels-Alder adduct). Similarly, monoolefinic hydrocarbons can act as a dienophile and react with triacylglycerol molecules having a fatty acyl chain which includes a diene moiety to form a 4+2 cycloadduct. Suitable monoolefinic compounds include cyclohexene, propene and butene. Alternatively, one of the double bonds of a diene such as cyclopentadiene or isoprene can act as a dienophile and react with a diene moiety within a fatty acyl chain of a triacylglycerol molecule. The diene moiety may exist naturally in the fatty acyl chain. More commonly, the double bonds of a polyunsaturated fatty acyl chain may be isomerized (e.g., by heating and/or by the addition of a catalyst such a iodine) to form a conjugated diene group within the chain. The olefinic hydrocarbons typically have a molecular weight of up to about 250 and preferably include no more than about 12 carbon atoms.
Lubricants including unsaturated triacylglycerols modified to have at least one fatty acyl chain
Cargill Incorporated
Medley Margaret
Merchant & Gould P.C.
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