Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
2000-08-16
2001-05-22
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S244000
Reexamination Certificate
active
06235686
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to lubricating compositions and, in particular, to lubricating compositions containing antioxidants.
It is well known that lubricants are susceptible to deterioration due to oxidation resulting in a decline of performance. The oxidation process leads to a loss of lubricating properties and an inadequate protection of a device or machinery to be lubricated. A general description of lubricants and lubricant oxidation can be found in Kirk-Othmer's Encyclopedia of Chemical Technology, Vol. 15, pp. 463-515 (4th Edition, 1995). The oxidation of lubricants normally proceeds via a free-radical mechanism. To inhibit oxidation, various compounds are added to lubricants to serve as oxidation inhibitors. The oxidation inhibitors function by breaking the free-radical chain reactions which lead to lubricant oxidation.
An example of one type of oxidation inhibitor is non-aromatized polymers of 2,2,4-trimethyl-1,2-dihydroquinoline (known as TMDQ). The polymerization of 2,2,4-trimethyl-1,2-dihydroquinoline and the use of TMDQ polymers with non-aromatic terminal units as oxidation inhibitors are disclosed in U.S. Pat. No. 2,908,646 to Roach et al., which is herein incorporated by reference.
Despite the availability of oxidation inhibitors, such as non-aromatized TMDQ polymers, there is a continuing need for new oxidation inhibitors that provide improved performance for lubricating compositions. Accordingly, it is an object of the present invention to provide lubricating compositions with increased performance.
SUMMARY OF THE INVENTION
It has now been discovered that TMDQ polymers and their homologs containing aromatized terminal units exhibit improved antioxidation properties in comparison with the non-aromatized TMDQ polymers. In accordance with the present invention, there is provided a lubricating composition containing a major amount of a base oil and an effective amount of an additive component which includes one or more compounds of formula (I):
The additive component containing the compound of formula (I) is present in a quantity between 0.01 and 10 percent by weight of the composition. Preferably, the additive component is present in a quantity of 0.1-5% by weight with 1-3% by weight being more preferred. The compound of formula (I) has a value for “n” ranging from 0-8. Preferably, “n” has a value of 0-6 with a value of 0-4 being more preferred. The base oil is preferably a base oil of lubricating viscosity.
In one preferred embodiment, the lubricating composition of the present invention contains an effective amount of an additive component which includes one or more compounds of formula (II):
In another preferred embodiment, the lubricating composition of the present invention contains an effective amount of an additive component which contains one or more compounds of formula (III):
The lubricating compositions of the present invention can also include one or more additional antioxidants and other conventional additives. Accordingly, lubricating compositions with improved performance are provided as will be further illustrated below.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides lubricating compositions that includes an additive component having one or more compounds with the formula (I):
where R is one of the following radicals: methyl, ethyl, n-propyl or i-propyl, or combinations thereof, and “n” has a value in the range of 0-8. Preferably “n” ranges from 0 to 6 with a range from 0 to 4 being more preferred.
The additive component containing the compound of formula (I) is added to the desired base oil of lubricating viscosity in an amount effective to prevent oxidation. An effective amount of the additive component can range, for example, from about 0.01 to about 10 percent by weight of the lubricating composition with about 0.1 to about 5.0 percent by weight being preferred, and with about 1 to about 3 percent by weight being more preferred.
In accordance with the present invention, the compositions of the present invention include lubricating oils and lubricating greases containing a major amount of base oil. The base oil may be, for example, a petroleum-based hydrocarbon oil or a synthetic oil, or mixture thereof. Any base oil of lubricating viscosity, as known in the art, can be used in accordance with the present invention. The representative petroleum-based oils are, for example, naphthenic, aromatic, and paraffinic mineral oils. The representative synthetic oils are, for example, the oils synthesized from alkylene polymers, carboxylic acid esters, polyglycol ethers, poly-&agr;-olefins, Pennzane (i.e., multiply alkylated cyclopentanes), and silahydrocarbons. Particularly preferred are the lubricant compositions based on a diester synthetic oil.
The non-aromatized dihydroquinoline (i.e., TMDQ) polymers are known in the art and may be obtained by polymerization of TMDQ or its analogs, as described by the Reaction
While not wishing to be bound by any one theory, it is believed that the polymerization reaction may proceed either through the 3-position or the 4-position carbon. The 4-position intermediates are stabilized by the alkyl R-group in the 4-position. However, the polymerization of TMDQ and its homologs can also produce polymers formed through the 3-position intermediates and mixtures polymers formed from the 3-position and 4-position carbons.
The compounds of formula (I) are obtained by aromatization of the terminal structural unit of TMDQ polymers or homologous polymers, as shown in the Reaction Scheme 2:
To obtain the aromatized polymers, the non-aromatized TMDQ or homologous polymers may be treated with strong base, for example, with sodium aniline to yield the corresponding aromatized polymers and methane. Alternatively, the aromatization is conducted in acidic conditions by treating the non-aromatized TMDQ polymers with an equivalent amount of hydrochloric acid.
As will be apparent from Reaction Scheme 2, the chemical structure of the compounds of formula (I) will depend upon the chemical structure of the starting TMDQ polymers. Therefore, it will be also apparent to one skilled in the art that the compounds of formula (I) may include polymers derived through the 4-position intermediates, 3-position intermediates, polymers with randomly alternating 3-position and 4-position-derived structural units, as well as a mixture of corresponding polymers with varying numbers of structural units.
Residual amounts of TMDQ or homologous monomers, corresponding aromatized monomers and non-aromatized TMDQ polymers may also be present due to the presence of these compounds in the reaction mixtures leading up to the aromatized polymers of formula (1). However, the TMDQ monomer should be present in an amount of less than 1 percent and preferably less than 0.1 percent.
In a preferred embodiment of the present invention, there is provided a lubricating composition containing a major amount of a mineral or synthetic oil, and an additive component containing one or more compounds of formula (II):
where R is one of the following radicals methyl, ethyl, n-propyl or i-propyl, or mixtures thereof and “n” ranges from 0 to 8, with 0 to 6 being preferred. More preferably, the additive component of this embodiment of the present invention contains one or more compounds of formula (II) with the number of structural units ranging from two to six (i.e., n=0-4). The additive component containing the compound of formula (II) is added to the base oil in an amount effective to prevent oxidation. An effective amount of the additive component can range, for example, from about 0.01 to about 10 percent by weight of the lubricating composition with about 0.1 to about 5.0 percent by weight being preferred, and with about 1 to about 3 percent by weight being more preferred.
In another preferred embodiment of the present invention, there is provided a lubricating composition containing a major amount of a mineral or synthetic oil, and an additive component containing one or more compounds of formula (III):
where
Donnelly Steven G.
Karol Thomas J.
McAvoy Ellen M.
Norris McLaughlin & Marcus P.A.
R.T. Vanderbilt Company, Inc.
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