Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic nitrogen compound
Reexamination Certificate
1994-11-23
2001-06-05
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic nitrogen compound
C508S542000, C508S557000, C508S561000
Reexamination Certificate
active
06242394
ABSTRACT:
SUMMARY OF THE INVENTION
This invention relates to lubricant compositions, and fuel-lubricant mixtures useful in two-stroke cycle engines. The invention also includes a method of controlling piston scuffing.
INTRODUCTION TO THE INVENTION
Over the past several decades the use of sparkignited two-cycle (two-stroke) internal combustion engines has steadily increased. They are presently found in power lawn mowers and other power-operated garden equipment, power chain saws, pumps, electrical generators, marine outboard engines, snowmobiles, motorcycles and the like.
The increasing use of two-stroke cycle engines coupled with increasing severity of the conditions in which they have operated has led to an increased demand for oils to adequately lubricate such engines. Among the problems associated with two-stroke cycle engines is piston lubricity, scuffing or scoring. This condition is generally controlled by adding relatively high viscosity oils (greater than or equal to 100 centistokes (cSt) at 40° C.) or bright stock. The higher viscosity oils and bright stock act to increase viscosity and prevent piston seizure. A problem associated with the use of these materials is deposit or varnish formation in the combustion chamber which may lead to preignition. High molecular weight polymers may be used to replace some or all of bright stock in two-stroke cycle engines. The polymer acts to increase viscosity and prevent piston seizure. The problem associated with the use of bright stock or high viscosity oils or high molecular weight polymers is that the products tend to cause fouling of the spark plug in a two-stroke cycle engine.
Aminophenols are useful in two-stroke cycle engines. U.S. Pat. Nos. 4,320,020 and 4,320,021 issued to Lange, relate to aminophenols and their use in lubricants. Aminophenols have been used in combination with dispersants and detergents. U.S. Pat. Nos. 4,100,082 and 4,200,545 relate to aminophenols used in combination with neutral or basic metal salts and amine dispersants in two-stroke cycle lubricants. U.S. Pat. No. 4,379,065 issued to Lange relates to aminophenols used in combination with ashless ester dispersants. U.S. Pat. No. 4,425,138 relates to aminophenols used in lubricant-fuel mixtures for two-stroke cycle engines.
U.S. Pat. Nos. 4,663,063 and 4,724,091 issued to Davis relate to a combination of an alkyl phenol and an amino compound in two-stroke cycle engines. The former relates to an alkyl phenol together with an amino compound other than an aminophenol. The latter relates to an alkyl phenol together with an aminophenol.
The unique problems and techniques associated with the lubrication of two-cycle engines has led to the recognition by those skilled in the art of two-cycle engine lubricants as a distinct lubricant type. See, for example, U.S. Pat. Nos. 3,085,975; 3,004,837; and 3,753,905.
The compositions of the present invention are effective in controlling piston scuffing. These benefits are obtained without requiring the use need of high molecular weight polymers, bright stock or high viscosity oils.
SUMMARY OF THE INVENTION
This invention relates to a lubricant composition for two-stroke cycle engines comprising:
a major amount of at least one oil of lubricating viscosity which is free of oils having a viscosity greater than or equal to 100 cSt at 40° C.,
an amount sufficient to reduce or prevent piston scuffing of a mixture of (A) at least one phenol selected from (A-1) an aminophenol and (A-2) a reaction product of a nitrophenol and an amino compound, and (B) at least one ashless dispersant. The compositions may also include up to about 10% by weight of (C) at least one polyalkene having a number average molecular weight from about 400 to about 2500.
Since lubricant compositions for two-stroke cycle engines are often mixed with fuels before or during combustion, Applicants' invention also includes fuel-lubricant mixtures. Applicants have discovered that the above compositons of the present invention act to control piston scuffing while also contributing to piston lubrication, deposit control, ring stick protection, reduced exhaust port blockage and reduced visible smoke emission. These lubricant compositions use oils which have a substantially lower viscosity than traditionally used oils. In another embodiment of the invention, the lubricant compositions are free of isostearic acid, or derivatives thereof.
The present invention further provides a lubricant composition suitable for fuel injected two-stroke cycle engines, comprising at least one oil of lubricating viscosity; an amount, sufficient to reduce or prevent piston scuffing, of a mixture of (A) at least one phenol selected from (A-1) an aminophenol and (A-2) a reaction product of a nitrophenol and an amino compound; and (B) at least one Mannich dispersant, amine dispersant, nitrogen-containing carboxylic dispersant, or ester dispersant; the composition further comprises (C′) an amount, sufficient to reduce degradation of the lubricant composition upon exposure to oxygen or to oxides of nitrogen, of a nitrogen-containing inhibitor, a hindered phenol inhibitor, or a sulfur-containing organic inhibitor.
DETAILED DESCRIPTION OF THE INVENTION
The term “hydrocarbyl” includes hydrocarbon, as well as substantially hydrocarbon groups. Substantially hydrocarbon describes groups which contain non-hydrocarbon substituents which do not alter the predominately hydrocarbon nature of the group.
Examples of hydrocarbyl groups include the following:
(1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, aromatic-, aliphatic- and alicyclic-substituted aromatic substituents and the like as well as cyclic substituents wherein the ring is completed through another portion of the molecule (that is, for example, any two indicated substituents may together form an alicyclic radical);
(2) substituted hydrocarbon substituents, that is, those substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent; those skilled in the art will be aware of such groups (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, sulfoxy, etc.);
(3) hetero substituents, that is, substituents which will, while having a predominantly hydrocarbon character within the context of this invention, contain other than carbon present in a ring or chain otherwise composed of carbon atoms. Suitable heteroatoms will be apparent to those of ordinary skill in the art and include, for example, sulfur, oxygen, nitrogen and such substituents as, e.g., pyridyl, furyl, thienyl, imidazolyl, etc. In general, no more than about 2, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group. Typically, there will be no such non-hydrocarbon substituents in the hydrocarbyl group. Therefore, the hydrocarbyl group is purely hydrocarbon.
When a substituent is defined as having an average number of carbon atoms, that average number of carbon atoms is based on number average molecular weight. However, the substituent does not have to have an average number of carbon atoms. The substituent may have a specific single number of carbon atoms, e.g., 18 carbon atoms.
(A) Phenols
The compositions of the present invention include an aminophenol or reaction product of a nitrophenol and an amino compound. The term “phenol” is used in this specification in its art-accepted generic sense to refer to hydroxy-aromatic compounds having at least one hydroxyl group bonded directly to a carbon of an aromatic ring. The aminophenols used in this invention contain at least one of each of the following substituents: a hydroxyl group and an R group as defined herein. Each of the foregoing groups must be attached to a carbon atom which is a part of an aromatic nucleus in the Ar moiety. They need not, however, each be attached to the same aromatic ring if more than one aromatic nucleus is present in the Ar moie
Esposito Michael F.
McAvoy Ellen M.
Shold David M.
The Lubrizol Corporation
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