Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2001-01-05
2003-04-22
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S496000
Reexamination Certificate
active
06551968
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to synthetic ester basestock blends based on polyneopentyl polyol (“PNP”) esters and, more particularly, to basestocks including PNP esters mixed with a coupling agent to increase compatibility with standard lubricant additive packages and provide a highly biodegradable lubricant formulation suitable for use in 2-stroke engines.
There is a continuing need to provide lubricant compositions which are highly biodegradable and are fully miscible with gasoline. This is particularly true with respect to lubricants for 2-stroke engines. These engines are often small gasoline engines used in recreational vehicles, such as motorboats, mono-skis for water use, snowmobiles and in lawn equipment. Thus, all such uses are in sensitive environments subject to pollution. Absent an acceptable biodegradabability level, exhaust and leakage of fuel mixed with the lubricant would tend to pollute forests, rivers, lakes and other waterways.
In order for lubricants for 2-stroke engines to be acceptable, they must provide a high viscosity index, acceptable biodegradability, miscibility with gasoline and be compatible with standard lubricant additive packages. Suitable viscometrics include good cold flow properties, such as a pour point less than about −40° C. and a viscosity at −40° C. of less than 36,000 cps and a suitably high flash point, greater than about 240° C.
Biodegradability is measured pursuant to ASTM- 5864 which is similar to the accepted Modified Sturm test adopted by the Organization for Economic Cooperation Development in 1979. These biodegradability tests involve the measurement of the amount of CO
2
produced by the test compound, which is, in turn, expressed as a percent of the theoretical CO
2
the compound could produce calculated from the carbon content of the test compound. The test is performed to measure released CO
2
trapped as BaCO
3
and is well known to those in the art and will not be set forth herein in detail. However, the generally accepted ASTM test procedure is incorporated herein by reference.
Generally, lubricants having a biodegradability of over 60% pursuant to ASTM-5864 or the Modified Sturm test are considered to have acceptable biodegradability characteristics.
Examples of biodegradable basestocks based on branched chain synthetic esters and lubricants formed therefrom are disclosed in U.S. Pat. No. 5,681,800. Here, branched chain fatty acids provide the desired viscometrics, low temperature properties, lubricity, biodegradability and solubility of additives therein.
While such biodegradable products are available, it remains desirable to provide a synthetic ester basestock providing all these desirable properties without the use of significant amounts of esters of branched chain acids which do not biodegrade as readily as esters based on straight chain acids.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, improved synthetic biodegradable polyneopentyl polyol (“PNP”) based ester basestocks and lubricants including conventional additive packages soluble therein are provided. The synthetic ester basestocks include PNP esters mixed with a coupling agent to aid in solubility of standard lubricant additive packages in the basestock. The PNP ester and coupling agent may then be blended further with lesser amounts of at least one additional high molecular weight linear or branched chain ester. The additional high molecular weight synthetic ester may be a polyol ester of a linear or branched chain monocarboxylic acid, a dicarboxylic acid ester of linear and/or branched chain monoalcohols, a linear and/or branched monocarboxylic acid ester of linear and/or branched chain monoalcohols, or mixtures thereof.
The PNP ester-coupling agent component of the basestock is a mixture of a polyneopentyl polyol ester, such as a polypentaerythritol ester (“poly PE ester”) and a coupling agent. The coupling agent is a compound of intermediate polarity between a hydrocarbon and the polyneopentyl polyol ester, such as esters having an oxygen content from about 4 to 16 weight percent, preferably from about 7 to 13 weight percent. In the preferred embodiment of the invention the coupling agent is an ester which is the reaction product of a dicarboxylic acid having between about 18 to 36 carbon atoms and a mono-alcohol having between about 6 to 14 carbon atoms. Most preferably, the coupling agent is a dimer acid ester which is the reaction product formed by the esterification of dimer acid with a monoalcohol, such as 2-ethylhexanol.
The PNP ester is present in the PNP ester-coupling agent mixture between about 55 to 80 weight percent. The preferred lubricant basestock also includes additional esters blended with the PNP ester and coupling agent mixture. The additional esters are added to adjust the viscometrics of the basestock and modify the lubricity and fluidity of the blend. Typically, the lubricant basestock includes between about 65 to 85 weight percent of the PNP ester-coupling agent mixture with the additional esters being the linear and/or branched chain alcohol-dicarboxylic acid esters, polyol-linear and/or branched monocarboxylic acid esters, linear and/or branched monocarboxylic acid-monoalcohol esters, or mixtures thereof as desired. The synthetic ester blends based on these compositions are then mixed with a standard lubricant additive package to form the biodegradable 2-stroke lubricant.
Accordingly, it is an object of the invention to provide a synthetic ester basestock having improved biodegradability suitable for use in 2-stroke lubricant formulations.
Another object of the invention is to provide an improved 2-stroke lubricant basestock based on polyneopentyl polyol based synthetic esters.
A further object of the invention is to provide an improved 2-stroke lubricant basestock including polyneopentyl polyol esters and a coupling agent to increase solubility of standard lubricant additive packages in the blend.
Yet a further object of the invention is to provide an improved 2-stroke lubricant basestock including polyneopentyl polyol esters and coupling agent admixed with additional high molecular weight esters for adjusting the viscometrics of the lubricant.
Yet another object of the invention is to provide an improved biodegradable polyneopentyl polyol ester based synthetic ester blend which provides the desired viscometrics, low temperature properties, lubricity, miscibility with gasoline and solubility of additives in the finished formulation.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises a composition of matter possessing the characteristics, properties, and the relation of components which will be exemplified in the compositions hereinafter described, and the scope of the invention will be indicated in the claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The biodegradable 2-stroke synthetic ester basestocks and lubricants prepared in accordance with the invention are blends which include at least two synthetic esters. These esters are a polyneopentyl polyol (PNP) ester admixed with a coupling agent. The coupling agent is a molecule that increases the solubility of standard lubricant additive packages in the PNP ester based lubricant. The coupling agent is a compound of intermediate polarity between a hydrocarbon and the polyneopentyl polyol ester, such as esters having an oxygen content from about 4 to 16 weight percent, preferably from about 7 to 13 weight percent. In order to attain the desired viscosity, pour point, flash point and other properties of the final basestock blend, one or more additional esters such as a polyol ester of a linear and/or branched chain monocarboxylic acid, a dicarboxylic acid ester of a linear and/or branched chain monoalcohol, or a linear and/or branched monocarboxylic acid ester of linear and/or branched chain monoalcohols, or mixtures thereof is additionally added to the PNP ester-coupling agent mixture.
In the
Carr Dale D.
McHenry Michael A.
Styer Jeremy P.
Hatco Corporation
McAvoy Ellen M.
Reed Smith LLP
Wolfson Michael I.
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