Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and...
Reexamination Certificate
1997-02-28
2003-08-26
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
C208S014000, C208S019000, C585S002000, C585S014000
Reexamination Certificate
active
06610634
ABSTRACT:
This invention relates to a lubricant composition useful as a two-cycle oil. More particularly the invention relates to two-cycle oil characterized in that it has a significantly reduced additive content, but provides an oil which complies with certain test standards for land equipment, gasoline fueled, two-cycle engines, such as motorcycle engines, moped engines, snowmobile engines, lawn mower engines and the like. Two-stroke-cycle gasoline engines now range from small, less than 50 cc engines, to higher performance engines of 200 to 500 cc. The development of such high performance engines has created the need for new two-cycle oil standards and test procedures.
Two-cycle engines are lubricated by mixing the fuel and lubricant and allowing the mixed composition to pass through the engine. Various types of two-cycle oils, compatible with fuel, have been described in the art. Typically, such oils contain a variety of additive components in order for the oil to pass industry standard tests to permit use in two-cycle engines.
U.S. Pat. No. 5,330,667 issued Jul. 19, 1994 to Tiffany et al. discloses a multi-component two-cycle oil comprising an acylated polyamine, a polyalkylene polyamine—polyisobutylene succinic anhydride reaction product, a polyolefin, a sulfurized alkylphenol and a phosphorous containing anti-wear agent.
U.S. Pat. No. 3,953,179 issued Apr. 27, 1976 to Souillard et al. discloses a two-stroke oil composed of hydrogenated or non-hydrogenated polybutene or polyisobutylene having a molecular weight of 250 to 2,000, 0.5 to 10% by weight of a triglyceride of an unsaturated carboxylic acid and 3 to 10 % by weight of conventional additives.
U.S. Pat. No. 5,049,291 issued Sep. 17, 1991 to Miyaji et al. teaches a two-cycle oil made up of 40 to 90% of a polymer or copolymer being either ethylene or ethylene alpha olefin polymers, 0 to 50% by weight of a polybutene, 5 to 50% by weight of a hydrocarbonaceous solvent and 2 to 20% by weight of a lubricating oil additive for two-cycle engines.
U.S. Pat. No. 5,321,172 issued Jun. 14, 1994 to Alexander et al. discloses solvent-free two-cycle oils composed of two different types of basestocks, 3 to 15% by weight of a polyisobutylene of Mn 400 to 1050, 3 to 15% by weight of polyisobutylene of Mn 1150 to 1650. This reference discloses that solvents may be deleted, thereby avoiding the safety risk associated with such materials.
U.S. Pat. No. 5,308,524 discloses a two-cycle oil exhibiting good miscibility with gasoline and superiority in detergency composed of an ester of a hindered alcohol and a C
5
-C
14
fatty acid, a polyoxyalkylene amino carbamate or an alkanol succinimide and a third component being a hydrocarbon having a boiling point of 500° or lower or an ether having an aromatic content of 2% below.
Japanese Kokai No. 7409504 published Jan. 28, 1974 discloses two-cycle engine oils which contain 5 to 50% by weight of a petroleum or synthetic hydrocarbon solvent and 10 to 95% by weight of a polyolefin having an average molecular weight of 200 to 200,000 and being soluble in the solvent. Such oils may also contain up to 40% by weight of a mineral oil. Three examples of the aforementioned publication shows polybutenes being present in amounts of 80%, 50% and 50% when the molecular weight is in the range of 570 to 1260 and another example shows the use of 30% polyisobutylene when the molecular weight is very high, that is, 100,000. The present invention is considered distinguished from this reference in that the polybutene used must be present in a very narrow range of 25 to 35% by weight and the molecular weight is only within the range of 300 to 1500.
The present invention is based on the discovery that the proper balance of a polybutene polymer, solvent and mineral oil can provide a two-cycle engine oil suitable for air-cooled two-stroke engines used commonly for land equipment. This invention avoids the need for complex and expensive additive systems.
Accordingly, there has been discovered a two-cycle lubricating oil composition having a viscosity of 6.5-14 cSt at 100° C. and a flash point greater than 70° C. consisting of:
a) 25 to 35% by weight of a polybutene polymer being a polybutene, polyisobutylene or a mixture of polybutenes and polyisobutylenes having a number average molecular weight of about 300 to 1500;
b) 20 to 35% by weight of a normally liquid solvent having a boiling point of up to 300° C.;
c) 30 to 40% by weight of a lubricating oil having a viscosity 20-40 cSt at 40° C.; and
d) 0-2% by weight of lubricating oil additives other than a polybutene.
The mixture of polybutenes preferably useful in the lubricating oil compositions of this invention is a mixture of poly-n-butenes and polyisobutylene which normally results from the polymerization of C
4
olefins and generally will have a number average molecular weight of about 300 to 1500 with a polyisobutylene or polybutene having a number average molecular weight of about 400 to 1300 being particularly preferred, most preferable is a mixture of polybutene and polyisobutylene having a number average molecular weight of about 950. Number average molecular weight (Mn) is measured by gel permeation chromatography. Polymers composed of 100% polyisobutylene or 100% poly-n-butene are also within the scope of this invention and within the meaning of the term “a polybutene polymer”.
A preferred polybutene polymer is a mixture of polybutenes and polyisobutylene prepared from a C
4
olefin refinery stream containing about 6 wt.% to 50 wt.% isobutylene with the balance a mixture of butene (cis- and trans-) isobutylene and less than 1 wt %. butadiene. Particularly, preferred is a polymer prepared from a C
4
stream composed of 6-45 wt. % isobutylene, 25-35 wt. % saturated butenes and 15-50 wt.% 1- and 2-butenes. The polymer is prepared by Lewis acid catalysis.
The solvents useful in the present invention may generally be characterized as being normally liquid petroleum or synthetic hydrocarbon solvents having a boiling point not higher than about 300° C. at atmosphere pressure. Such a solvent must also have a flash point in the range of about 60-120° C. such that the flash point of the two-cycle oil of this invention is greater than 70° C. Typical examples include kerosene, hydrotreated kerosene, middle distillate fuels, isoparaffinic and naphthenic aliphatic hydrocarbon solvents, dimers, and higher oligomers of propylene butene and similar olefins as well as paraffinic and aromatic hydrocarbon solvents and mixtures thereof. Such solvents may contain functional groups other than carbon and hydrogen provided such groups do not adversely affect performance of the two-cycle oil. Preferred is a naphthenic type hydrocarbon solvent having a boiling point range of about 91.1° C.-113.9° C. (196°-237° F.) sold as “Exxsol D80” by Exxon Chemical Company.
The third component of the lubricating compositions of this invention is an oil of lubricating viscosity, that is, a viscosity of about 55-180 cSt at 40° C., to provide a finished two-cycle oil in the range of 6.5-14 cSt at 100° C.
These oils of lubricating viscosity for this invention can be natural or synthetic oils. Mixtures of such oils are also often useful. Blends of oils may also be used so long as the final viscosity is 55-180 cSt at 40° C.
Natural oils include mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.
Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof.
Oils made by polymerizing olefins of less than 5 carbon atoms and mixtures thereof are typical synthetic polymer oils. Methods of preparing such polymer oils are well known to those skilled in the art as is shown by U.S. Pat. Nos. 2,278,445; 2,301,052; 2,318,719; 2,329,714; 2,345,574; and 2,422,443.
Al
L'Heureux George Conrad
Smythe John Henry
Tiffany, III George Mortimer
Exxon Chemical Patents Inc.
Medley Margaret
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