Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heavy metal or aluminum in an organic phosphorus compound...
Reexamination Certificate
2001-09-19
2004-06-15
McAvoy, Ellen M (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heavy metal or aluminum in an organic phosphorus compound...
C508S378000, C508S501000, C508S503000, C508S563000
Reexamination Certificate
active
06750184
ABSTRACT:
The present invention relates to improved lubricant compositions, which are highly resistant to oxidative degradation, and which comprise selected phenolic and amine antioxidants. The invention also relates to the use of these lubricant compositions for improving the performance properties of lubricants, such as greases, metalworking fluids, gear fluids and hydraulic fluids.
It is known that additives improve the performance properties of lubricants, such as mineral oils or synthetic or semi-synthetic oils. Particularly additives are highly desirable which reduce the formation of oxidative degradation products and promote a long shelf life and high performance stability of lubricants.
The technical requirements for modern motor oils under the conditions of high temperature oxidation, as expressed by recent technical specifications, have become more severe. According to recent developments in the construction of combustion engines, particularly spark ignition internal combustion engines, higher amounts of nitrogen oxides (NO
x
) are produced which reenter the crankcase as blow-by gases.
The lubricating oil also functions in the combustion chamber as a tight seal between the up-stroke of the piston and the cylinder head resulting in a contamination with high-boiling fuel components. These functions deteriorate in the presence of NO
x
-gases.
Blow-by gases with increasing NO
x
-content enhance the susceptibility of the lubricating oil to oxidation and the formation of undesirable oxidation products. Nuclei for deposits are formed which ultimately generate undesirable deposits, popularly known as black sludge. It is assumed that this degradation process is caused by NO
x
-initiated autooxidation of the lubricating oil. Many attempts have been made to improve the performance of lubricating oils by the addition of different antioxidants.
EP-A-0 346 283 discloses phosphite-free lubricating oil compositions which comprise, among others, phenolic antioxidants in combination with different aromatic amines and mixtures of these amines. So-called sterically hindered phenolic antioxidants are specifically disclosed wherein the phenolic group is substituted in 3- and 5-position with tert.-butyl groups.
EP-A-0 781 834 discloses lubricating oil compositions which comprise 5-tert.-butyl-4-hydroxy-3-methylphenyl substituted fatty acid ester in combination with conventional oil additives other than diphenylamines.
The Japanese Published Patent Application Hei 11-209777 discloses lubricating oil compositions which comprise 3-(5-tert.-butyl-4-hydroxy-3-methylphenyl)propionic acid C
5
- and -C
13
alkyl esters in combination with alkylated diphenylamines. No additional additives are specifically disclosed. The composition is used for preventing the discoloration of lubricating oils. No other technical uses and applications or improved antioxidative properties are disclosed.
EP-A-0 896 050 discloses lubricating oil compositions which comprise a large group of different phenolic antioxidants of divergent structures in combination with different aromatic amines and sulfur containing oil additives. Among them zinc dithiophosphates are disclosed.
Novel lubricant compositions have now been found which possess improved antioxidative properties as compared with the prior art compositions. The novel lubricant compositions comprise a selected group of 5-tert.-butyl-4-hydroxy-3-methylphenyl substituted fatty acid esters in combination with specific diphenylamines and zinc dithiophosphates. The novel lubricant compositions are highly resistant to oxidative degradation and are capable of reducing the negative effects of deposits, such as black sludge, in motor combustion engines, particularly spark ignition internal combustion engines.
The present invention relates to a composition, which comprises:
a) a base oil of lubricating viscosity;
b) at least one phenol of the formula:
wherein
R
1
represents branched C
8
-C
22
alkyl;
c) at least one aromatic amine of the formula:
wherein R
1
and R
2
represent hydrogen or together represent the group:
and one of R
3
and R
3
′ represents hydrogen and the other one C
2
-C
30
alkyl or both R
3
and R
3
′ represent C
2
-C
30
alkyl; and
d) at least one zinc dithiophosphate of the formula
wherein R
1
and R
2
represent straight chained or branched C
3
-C
20
alkyl.
The compositions defined above containing 5-tert.-butyl-4-hydroxy-3-methylphenyl substituted fatty acid esters are characterized by their superior antioxidative properties as compared with the corresponding compositions containing 3,5-di-tert.-butyl-4-hydroxyphenyl substituted fatty acid esters. This can be demonstrated in various commonly accepted tests such as Deposit and Oxidation Panel Test (DOPT) and Pressurized Differential Scanning Calorimetry (PDSC).
The compositions according to the instant invention are particularly suitable for use as lubricants having excellent antioxidative properties in internal combustion engines, such as spark-ignition internal combustion engines (popularly known as Otto motor engines) or self-ignition internal combustion engines (popularly known as Diesel motor engines).
The compositions are particularly suitable as motor oils which correspond in the API (American Petroleum Institute) classification to the categories SF, SG and CD, in the CRC (Coordinating Research Council) classification to the standardized Caterpillar Tests 1-G 1 or 1-G 2 and in the CCMC (Committee of Common Market Automobile Constructors) classification to the specifications G 1, G 2, G 3, D 1, D 2, D 3 and/or PD 1.
The definitions and general terms used in the description of the present invention preferably have the following meanings:
Component a)
A base oil of lubricating viscosity can be used for the preparation of engine oils, gear fluids, or hydraulic fluids, but also for fuel additives, greases or metal working fluids.
Suitable engine oils, gear fluids and hydraulic fluids are based, for example, on mineral oils or synthetic oils or mixtures thereof. The lubricants are known and familiar to the person skilled in the art and are described in standard reference books, such as in
Chemistry and Technology of Lubricants
; Mortier, R. M. and Orszulik, S. T. (Editors); 1992 Blackie and Son Ltd. for GB, VCH-Publishers N.Y. for U.S., ISBN 0-216-92921-0, pages 208 et seq. and 269 et seq.; in
Kirk
-
Othmer Encyclopedia of Chemical Technology
, Fourth Edition 1969, 1. Wiley & Sons, New York, Vol. 13, page 533 et seq. (Hydraulic Fluids);
Performance Testing of Hydraulic Fluids
; R. Tourret and E. P. Wright, Hyden & Son Ltd. GB, on behalf of The Institute of Petroleum London, ISBN 0 85501 317 6
; Ullmann's Encydopedia of Ind. Chem., Fifth Completely Revised Edition
, Verlag Chemie, DE-Weinheim, VCH-Publishers for U.S., Vol. A 15, page 423 et seq. (lubricants), Vol. A 13, page 165 et seq. (hydraulic fluids).
The base oil of lubricating viscosity is preferably a mineral oil derived lubricating base oil containing 80% by mass or more of a saturated hydrocarbon component. Various methods for producing the mineral oil derived lubricating base oil are available. For example, the lubricating base oil may be a paraffin oil or a naphthenic oil obtainable by subjecting a lubricating oil fraction derived from an atmospheric or vacuum distillation of crude oil to refining processes such as deasphalting, solvent refining such as solvent extraction with furfural, hydrocracking, solvent or catalytic dewaxing, such as solvent or catalytic dewaxing, hydrotreating, such as hydrocracking or hydrofinishing, clay treatment, such as washing with acid treated or activated clay, or chemical refining such as washing with caustic soda or sulfuric acid and the like. Combinations of these methods are also available for producing the mineral oil derived lubricating base oil.
Preferred methods for producing the mineral oil derived lubricating base oil consists of the following technical procedures, wherein one of the following oils is used as feedstock oil:
1) a distillate derived from the atmospher
Dubs Paul
Laemlin Serge
Ribeaud Marc
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
McAvoy Ellen M
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