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
2002-11-12
2004-05-11
Howard, Jacqueline V. (Department: 1764)
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...
C508S363000, C508S501000, C508S503000
Reexamination Certificate
active
06734150
ABSTRACT:
This invention relates to lubricating oil compositions, especially lubricants used in internal combustion engines, comprising base oils high in saturates which are resistant to oxidation.
Lubricating oil compositions are used for the smooth operation of internal combustion engines, power transmission components including automatic transmissions, shock absorbers and power steering devices and gears. The engine oils for internal combustion engines in particular serve to (i) lubricate various sliding interfaces eg between the piston ring and cylinder liner, in bearings of the crank shaft and the connecting rod, and in the valve driving mechanism including cams and valve lifters, (ii) cool the engine, (iii) clean and disperse the combustion products and (iv) prevent corrosion and consequent rust formation. The stringent requirements for high performance engines in recent years has meant greater demand from lubricants used in such engines. Lubricating oils used in such engines usually deteriorate due to oxidation by oxygen and nitrogen oxides (NOx) formed during combustion of fuels and lubricants and that contained in blow-by gas in turn formed by leakage of combustion gases into the crankcase via the piston and cylinder interface. The concentration of NOx increases in the blow-by gas with increasing demand in performance of the engine. The deleterious effects of oxidation can be and have been mitigated by the use of various additives including antioxidants, anti-wear agents, ash-free detergent dispersants, friction modifiers and the like.
Hitherto these have been mitigated to some extent by the use of lubricating compositions which comprise a Group I base oil which is relatively low in saturated hydrocarbons (hereafter “saturates”) in spite of its relatively high propensity to oxidation. Whilst this has meant that the base oil itself is relatively inexpensive, it has had to be supplemented with relatively large amounts of additives/antioxidants to achieve the desired performance. However, by using a relatively more refined feedstock such as the Group II & Group III basestocks high in saturates, it is possible to achieve the desired performance without unduly supplementing the additives/antioxidants used.
It has now been found that by using a specific combination of antioxidants, it is possible to use Group II and Group III base stocks high in saturates with enhanced performance in respect of oxidation stability and fuel efficiency.
Accordingly, the present invention is a lubricating oil composition comprising a base stock and an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula:
Mo
3
S
x
—(Q) (I)
wherein x is from 4 to 10, preferably 7, and Q is a core group, which may be a ligand, and at least one other compound selected from a phenolic and an aminic compound characterised in that the base stock has a kinematic viscosity at 100° C. (KV
100
) from about 2 cSt to 20 cSt (2×10
−6
to 20×10
−6
m
2
/sec) and a saturates content of at least 85%.
The lubricating oil compositions of the present invention are those that comprise a major amount of a Group II or Group III base stock which may be a natural or synthetic lubricating oil having a KV
100
of 2-20 cSt, preferably from 2-12 cSt and a saturates content of at least 85%, preferably at least 88%. Specific examples of Group II basestock high in saturates include inter alia RLOP 500R and Mobil Jurong 500N (with >97% saturates), and MXT 5 (with 92% saturates); and examples of Group III basestock include inter alia Yubase 4 (with saturate contents of 99.5%) and Yubase 6 (with saturate contents of 97.5%).
According to a further embodiment, the present invention is a method of stabilizing a lubricant composition against oxidative degradation, said composition comprising a base stock which has a kinematic viscosity at 100° C. (KV
100
) from about 2 cSt to 20 cSt (2×10
−6
to 20×10
−6
m
2
/sec) and a saturates content of at least 85% said method comprising adding to the basestock an effective amount of an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula:
Mo
3
S
x
—(Q) (I)
wherein x is from 4 to 10, preferably 7, and Q is a core group, which may be a ligand, and at least one other compound selected from a phenolic and an aminic compound.
The trinuclear molybdenum compounds are of formula (I)
Mo
3
S
x
—(Q) (I)
wherein x is from 4 to 10, preferably 7, and Q is a core group. These compounds are relatively new and are claimed and described in our prior published U.S. Pat. No. 5,906,968. The matter disclosed in this prior U.S. patent on the structure, preparation and properties of the trinuclear molybdenum compounds is incorporated herein by reference. In these compounds the core group (Q) may be a ligand capable of rendering the organomolybdenum compound of formula (I) oil soluble and ensuring that said molybdenum compound is substantially charge neutral. The core group (Q) is generally associated with suitable ligands such as L, wherein L is the ligand and y is of a sufficient number, type and charge to render the compound of formula (I) oil soluble and to neutralise the charge on the compound of formula (I) as a whole. Thus, more specifically, the trinuclear molybdenum compound used in the compositions of the present invention may be represented by the formula (II):
Mo
3
S
x
L
y
(II)
The ligands “L” are suitably dihydrocarbyl dithiocarbamates of the structure (—S
2
CNR
2
) wherein the dihydrocarbyl groups, R
2
impart oil solubility to the molybdenum compound. In this instance, the term “hydrocarbyl” denotes a substituent having carbon atoms directly attached to the remainder of the ligand and is predominantly hydrocarbyl in character within the context of this invention. Such substituents include the following:
(1) hydrocarbon substituents, ie, aliphatic (for example alkyl or alkenyl), alicyclic (for example cycloalkyl or cycloalkenyl), aromatic-, aliphatic- and alicyclic-substituted aromatic nuclei and the like, as well as cyclic substituents wherein the ring is completed through another portion of the ligand (that is, any two indicated substituents may together form an alicyclic group);
(2) substituted hydrocarbon substituents, ie, those containing nonhydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbyl character of the substituent. Those skilled in the art will be aware of suitable groups (eg halo (especially chloro), amino, alkoxyl, mercapto, alkylmercapto, nitro, nitroso, sulphoxy etc.); and
(3) hetero substituents, ie, substituents which, while predominantly hydrocarbon in character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms.
The hydrocarbyl groups are preferably alkyl (e.g. in which the carbon atom attached to the remainder of the ligand “L” is primary, secondary or tertiary), aryl, substituted aryl and/or ether groups.
Importantly, the hydrocarbyl groups of the ligands should be such that they have a sufficient number of carbon atoms to render the compound (I) soluble or dispersible in the oil to which the trinuclear organomolybdenum compound containing the ligand is added. The total number of carbon atoms present among all of the hydrocarbyl groups of the organomolybdenum compounds' ligands is suitably at least 21, preferably at least 25, more preferably at least 30 and even more preferably at least 35, typically e.g., 21 to 800. For instance, the number of carbon atoms in each hydrocarbyl group will generally range from 1 to 100, preferably from 1 to 40 and more preferably from 3 to 20.
The antioxidant in the compositions of the present invention suitably also include at least one other compound selected from a phenolic compound and an aminic compound. Among the phenolic compounds, hindered phenols are preferred.
Examples of such phenolic compounds include inter alia:
4,4′-methylene bis(2,
Gao Jason Zhisheng
May Christopher John
Torkelson Jeffrey Robert
Woolley Paul Simon
ExxonMobil Research and Engineering Company
Foss Norby L.
Howard Jacqueline V.
LandOfFree
Lubricating oil compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lubricating oil compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lubricating oil compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3260024