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
2000-06-02
2001-10-09
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...
C508S572000, C508S591000
Reexamination Certificate
active
06300290
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 contains a VI improver, but provides an oil which complies with certain test standards and viscosity requirements 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 exceeding 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. 3,544,466 issued Dec. 1, 1970 to McDowell et al. discloses two cycle oils with VI improvers but not in combination with solvents.
Similarly, GB 2,081,299 (1982) discloses two cycle oils containing lower alkanols which may also have VI improvers, but not in combination with solvents.
The present invention is based on the discovery that the proper balance of a polybutene polymer, solvent and a VI improver can provide a two-cycle engine oil of superior viscosity properties.
Accordingly, there has been discovered a two-cycle lubricating oil composition having a Brookfield viscosity of less than 17,000 cP at −40° C. and a kinematic viscosity of at least 6.5 mm
2
/s (cSt) at 100° C. comprising an admixture of:
(a) 3 to 50% 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 400 to 1500;
(b) 5 to 45% by weight of a normally liquid hydrocarbon solvent having a boiling point of up to 380° C.;
(c) 0.01 to 1% by weight of a viscosity index improver;
(d) 20 to 70% by weight of a mineral or synthetic oil of lubricating viscosity; and
(e) 1 to 25% by weight of an additive package for two cycle lubricating oil additives such additives being present in an amount to satisfy the JASO M345 standards for two cycle lubricating oil compositions.
All percentages are by weight on an active ingredient basis based on the weight of the fully formulated lubricating oil composition.
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 380° 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 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 192° C.-250° C. sold as “Exxsol D80” by Exxon Chemical Company. Preferably, there will be employed 10-40% by weight of the solvent or a mixture of solvents.
Suitable viscosity index improvers that may be added to the present lubricating oil compositions include oil soluble polymers having a weight average molecular weight of from about 10,000 to 1,000,000, preferably 20,000 to 500,000, as determined by gel permeation chromatography or light scattering methods. They are used in amounts of from 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight.
Representative examples of such polymers include polyisobutylene, copolymers of ethylene and propylene and higher alpha-olefins, polymethacrylates, methacrylate copolymers, polyalkylmethacrylates, copolymers of styrene and acrylic esters, copolymers of a vinyl compound and an unsaturated dicarboxylic acid, and partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, and isoprene/butadiene, as well as the partially hydrogenated homopolymers of butadiene and isoprene and copolymers of isoprene/divinylbenzene.
Preferred viscosity index improvers are ethylene copolymers containing from 15 to 90 wt. % ethylene, preferably 30 to 80 wt. % of ethylene and 10 to 85 wt. %, preferably 20 to 70 wt. % of one or more C
3
to C
28
, preferably C
3
to C
18
, more preferably C
3
to C
8
, alpha-olefins. While not essential, such copolymers preferably have a degree of crystallinity of less than 25 wt. %, as determined by X-ray and differential scanning calorimetry. Copolymers of ethylene and propylene are most preferred. Terpolymers, tetrapolymers, etc., of ethylene, said C
3
-C
28
alpha-olefin, and a non-conjugated diolefin or mixtures of such diolefins may also be used. The viscosity modifiers may also be derivatized to include other properties or functions, such as the addition of dispersancy properties. These oil soluble viscosity modifying polymers will generally have number average molecular weight of from 1,000 to 1,000,000, e.g. 20,000 to 250,000, as determined by gel permeation chromatography or osmometry.
The fourth component of the lubricating compositions of this invention is an oil of lubricating viscosity, that is, a viscosity of about 20-180, preferably 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 20-180 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.
L'Heureux George C.
Tiffany George M.
Infineum International LTD
McAvoy Ellen M.
LandOfFree
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