Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Nitrogen and heavy metal – or nitrogen and aluminum – in the...
Reexamination Certificate
1997-04-22
2001-10-23
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Nitrogen and heavy metal, or nitrogen and aluminum, in the...
Reexamination Certificate
active
06306802
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to lubricating oil additives, and to lubricating oil compositions and concentrates prepared therefrom. More specifically it relates to an additive containing a combination of a molybdenum compound and an aromatic amine compound as an antioxidant.
DESCRIPTION OF THE PRIOR ART
Lubricating oils as used in, for example, the internal combustion engines of automobiles or trucks are subjected to a demanding environment during use. This environment results in the oil suffering oxidation which is catalysed by the presence of impurity species in the oil such as iron compounds and is also promoted by the elevated temperatures experienced by the oil during use. This catalysed oxidation of the oil contributes to the formation of corrosive oxidation products and sludge in the oil but can also cause the viscosity of the oil to increase or even cause the oil to solidify. This oxidation of lubricating oils during use is usually controlled to some extent by the use of antioxidant additives which may extend the useful life of the oil particularly by reducing or preventing unacceptable viscosity increases.
There is, however, a continuing need for new antioxidants and antioxidant systems which offer improved performance and which are effective at low levels. There are a number of factors which have contributed to this continuing need. One such factor is that in recent years internal combustion engines are often operated at higher temperatures which tends to increase the rate of oxidation and so shorten the useful life of the oil. In addition there is a strong desire to use cheaper base stocks for lubricating oil compositions which have inferior resistance to oxidation and require more efficient and effective antioxidants. There is also a need for lubricating oils to have a longer in service life span due to the service intervals for motor vehicles becoming longer. There is also a desire to find antioxidants and antioxidant systems which meet the above requirements and at the same time are not detrimental to other aspects of motor vehicle performance. In this respect there is a desire for antioxidants which do not contribute to the phosphorus content of motor vehicle exhausts as phosphorus is detrimental to the performance of catalyst based exhaust purification systems. In addition some antioxidants such as for example diphenylamines cannot be used at relatively high concentrations as this may result in sedimentation or deposits in hot engine areas such as the diesel ring areas in diesel engines. The invention is concerned with the problem of providing an improved antioxidant for use in lubricating oils.
We have now discovered that a combination of certain molybdenum containing compounds and certain aromatic amines is a highly effective regenerative antioxidant system for use in lubricating oils and especially in lubricating oils for gasoline and diesel engines.
There have been a number of proposals for the use of molybdenum compounds as antioxidants for lubricating oils such as those described in U.S. Pat. No. 3,356,702, U.S. Pat. No. 4,098,705, U.S. Pat. No. 4,265,773, U.S. Pat. No. 4,285,882, U.S. Pat. No 4,369,119, U.S. Pat. No. 4,370,246, U.S. Pat. No. 4,394,279, U.S. Pat. No. 4,846,983 and EP 0,205,165. Both U.S. Pat. No. 4,370,246 and U.S. Pat. No. 4,394,279 describe the use of combinations of specific molybdenum compounds with aromatic amines wherein the molybdenum compounds are prepared from the reaction of an acidic molybdenum compound with a basic nitrogen compound selected from either Mannich bases phosphonamides, thiophosphonamide, phosphoramide, succinamide, carboxylic acid amide, dispersant viscosity index improvers or mixtures thereof and either carbon disulfide or other sulphur containing compounds.
SUMMARY OF THE INVENTION
According to the present invention there is provided a lubricating oil additive which comprises a combination of an oil-soluble molybdenum containing and of general formula I:
wherein R
1
, R
2
, R
3
and R
4
may be the same or different and each independently represent a C
7
to C
24
hydrocarbyl radical, X and X
1
may be the same or different and independently represent S or O, and the Mo is in oxidation state five or less; and at least one oil-soluble aromatic amine.
By the term hydrocarbyl radical is meant an organic moiety which comprises hydrogen and carbon and which unless the context states otherwise may be aliphatic (including alicyclic), aromatic or a combination thereof. It may be substituted or unsubstituted, alkyl, aryl or alkaryl and may optionally contain unsaturation or heteroatoms such as O, N or S. It is preferred that the hydrocarbyl radical does not contain heteroatom substitution. It is preferred that the hydrocarbyl radical is a hydrocarbyl radical of C
10
to C
18
and most preferably is a C
12
aliphatic hydrocarbyl radical. Examples of suitable aliphatic hydrocarbyl radicals include, 2-ethyihexyl, nonylphenyl, dodecyl, pentyl, cyclohexyl, phenylmethyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, or t-butyl. The choice of R
1
, R
2
, R
3
and R
4
must be such that the resulting molybdenum compound of general structure I is oil-soluble.
It is preferred that X and X
1
are the same. It is most preferred that X and X
1
are S.
By the term aromatic amine is meant any secondary amine with at least one aromatic group; such an amine gives a synergistic antioxidant effect when used in combination with a molybdenum compound of general formula I.
It is preferred that the oil-soluble secondary aromatic amines are diphenylamines of general formula II:
wherein R
5
and R
6
may be the same or different and each independently represents a hydrocarbyl radical as hereinbefore defined. It is preferred that R
5
and R
6
are C
1
to C
28
aliphatic hydrocarbyl radicals. A and B may be the same or different and may equal 0, 1, 2 or 3. It is preferred that A and B are the same and that they equal 1. It is also preferred that the diphenylamines have a nitrogen content of between 2.5 and 5% by weight. It is preferred that R
5
and R
6
are located in the meta or para positions relative to the amino substitution in the aromatic rings of the diphenylamines. Examples of suitable diphenylamines include di-octyidiphenylamine, t-pentyldiphenylamine, diisobornyidiphenyiamine, didecyidiphenylamine, didodecyldiphenylamine, dihexyldiphenylamine, di-t-butyidiphenylamine, di-t-octyldiphenylamine, dinonylamine, dibutyldiphenylamine, distyryidiphenylamine. Other suitable diphenylamines include di-substituted derivatives wherein the R
5
and R
6
are different and independently represent hydrocarbyl radicals such as for example t-butyl, t-octyl, styryl, n-butyl or n-octyl. Some of these diphenylamines are commercially available and are sold under the trademarks, Vanlube DND, Naugalube 438L, Pearsall OA502, Lubrizol 5150A, Vanlube SL, Naugalube 680, Inganox L-57 and Vanlube 848. Vanlube DND, Naugalube 438L, Pearsall OA502 and Lubrizol 5150A nominally have structures as represented by general formula II wherein R
5
and R
6
are C
9
hydrocarbyl groups and A=B=1. Vanlube SL and Naugalube 680 nominally have structures as represented by general formula II wherein R
5
and R
6
are either one of C
4
, C
8
or styryl hydrocarbyl groups and A=B=1; these are mixed diphenyl amines. Irganox L-57 and Vanlube 848 nominally have structures as represented by general formula II wherein R
5
and R
6
are either one of t-butyl or t-octyl groups and A=B=1.
Some of the oil-soluble molybdenum compounds of Formula I are commercially available. For example products where X and X
1
are O and where R
1
, R
2
, R
3
and R
4
are C
13
H
27
aliphatic hydrocarbyl groups and where the molybdenum is in oxidation state V are sold under the trademarks Molyvan 807 and Molyvan 822 as antioxidants and friction reducing additives by R.T. Vanderbilt Company Inc. Norwalk Conn. USA. These molybdenum compounds may be prepared by the methods described in U.S. Pat. No. 3,356,702 wherein MoO
3
is converted to solubl
Exxon Chemical Patents Inc.
Medley Margaret
Toomer Cephia D.
LandOfFree
Mixed antioxidant composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mixed antioxidant composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mixed antioxidant composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2615932