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
2000-12-11
2002-09-24
Howard, Jacqueline V. (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...
C508S390000, C508S502000, C508S586000
Reexamination Certificate
active
06455477
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 relatively low amount of polyisobutylene, but provides an oil which complies with certain smoke generation 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.
The present invention is based on the discovery that the proper balance of a polybutene polymer, solvent and lubricating oil basestock can provide a two-cycle engine oil of suitable viscosity properties which exceeds the JASO (Japan Automobile Standards Organization) M342 Smoke Index test.
Accordingly, there has been discovered a two-cycle lubricating oil composition having a kinematic viscosity of at least 6.5 mm
2
/s (cSt) at 100° C. and a JASO M342 Smoke Index of at least 85 comprising an admixture of:
(a) 5 to 20% 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 2200;
(b) 30 to 45% by weight of a normally liquid hydrocarbon or mineral oil solvent having a viscosity of 2 to 12 mm
2
/s (cSt) at 40° C.;
(c) 0 to 10% by weight of an additive package for two cycle lubricating oil additives such additives being present in such amounts to satisfy the JASO M345 detergency standards for two cycle lubricating oil compositions; and
(d) the balance a lubricating oil having a viscosity of 20 to 180 mm
2
/s (cSt) at 40° C.
All percentages are by weight on an active ingredient basis based on the weight of the fully formulated lubricating oil composition, unless otherwise stated.
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 400 to 2200 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”. Preferably there is employed 10 to 20%, most preferably 12 to 15% by weight of the 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 natural or synthetic hydrocarbon or mineral oil solvents having a viscosity of 2 to 12, preferably 3 to 5 mm
2
/s (cSt) at 40° C. 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 paraffinic, isoparaffinic and naphthenic aliphatic hydrocarbon or mineral oil solvents. 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 paraffinic mineral oil solvent having a viscosity of 3.5 to 4.0 mm
2
/s (cSt) at 40° C. sold as “Sun HPO 40” by Sun Oil Company. Preferably, there will be employed 35-40% by weight of the solvent or a mixture of such solvents, such as 38 or 39%.
The proper balance of solvent and polybutene polymer is the essential aspect of the present invention. Traditionally in the two cycle lubricating field, formulations have required 22-30% polybutene polymer with a lower viscosity solvent such as kerosene in order to satisfy the JASO M342 Smoke Index value of at least 85. However, use of a relatively low viscosity solvent such as kerosene, while contributing to smoke performance, adversely affects kinematic viscosity (KV) which must be 6.5 mm
2
/s (cSt) or higher at 100° C. to meet JASO requirements for a commercially useful product. The formulation of this invention, which is kerosene-free, and free of solvents having viscosity less than 2.0 mm
2
/s (cSt) at 40° C., preferably less than 3.0 mm
2
/s (cSt) at 40° C., achieves a cost reduction by minimizing the amount of the polybutene polymer, an expensive ingredient, but at the same time satisfying the KV and JASO Smoke Index requirements.
The invention further comprises as a third component the presence of 0-10%, preferably 1-7%, by weight of an additive package which contains one or more conventional two-cycle lubricating oil additives, and these may be any additive normally included in such lubricating oils for a particular purpose.
Such conventional additives for the additive package component which may be present in the composition of this invention include corrosion inhibitors, oxidation inhibitors, friction modifiers, dispersants, antifoaming agents, antiwear agents, pour point depressants, metal detergents, rust inhibitors, lubricity agents, which are preferred, and the like. All percentages are by weight on an active ingredient (a.i.) basis.
A preferred additive package will comprise (i) polyisobutenyl (Mn 400-2500, preferably Mn 950) succinimide or another oil soluble, acylated, nitrogen containing lubricating oil dispersant present in such amount to provide 0.2-5 wt. %, preferably 1-3 wt. % dispersant in the lubricating oil and (ii) a metal phenate, sulfonate or salicylate oil soluble detergent additive, which is a neutral metal detergent or overbased such that the Total Base Number is 200 or less, present in such amount so as to provide 0.1-2 wt. %, preferably 0.2-1 wt. % metal detergent additive in the lubricating oil. The metal is preferably calcium, barium or magnesium. Neutral calcium salicylates are preferred present in amounts of about 0.5 to 1.5 wt. % in the lubricating oil.
Corrosion inhibitors are present in the oil in amounts of 0.01-3 wt. %, preferably 0.01-1.5 wt. %, and are illustrated by phosphosulfurized hydrocarbons and the products obtained by reacting a phosphosulfurized hydrocarbon with an alkaline earth metal oxide or hydroxide. Benzotriazole (35 wt. % active ingredient in propylene glycol) is preferred for use in this invention.
Oxidation inhibitors are present in the oil in amounts of 0.01-5 wt. %, preferably 0.01-1.5 wt. % and are antioxidants exemplified by alkaline earth metal salts of alkylphenol thioesters having preferably C
5
-C
12
alkyl side chain such as calcium nonylphenol sulfide, barium t-octylphenol sulfide, dioctylphenylamines as well as sulfurized or phosphosulfurized hydrocarbons. Also included are oil soluble antioxidant copper compounds such as copper salts of C
10
to C
18
oil soluble fatty acids.
Friction modifiers are present in the oil in amounts of 0.01-3 wt. %, preferably 0.01-1.5 wt. %, and include fatty
Howard Jacqueline V.
Infineum International Ltd.
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