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
2000-05-18
2002-06-25
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...
C508S262000, C508S279000, C508S281000
Reexamination Certificate
active
06410490
ABSTRACT:
The instant invention is directed to a lubricant composition stabilized against the deleterious effects of heat and oxygen, said composition comprising a hydrotreated or hydrodewaxed oil and an effective antioxidant stabilizing amount of a mixture of a phenolic antioxidant; an N,N-disubstituted aminomethyl-1,2,4triazole; an aromatic amine antioxidant; an alkyl phenoxy alkanoic acid; and an N-acyl sarcosine derivative.
The instant compositions find utility in industrial lubricant applications such as, for example, compressor, hydraulic, turbine oils and the like.
BACKGROUND OF THE INVENTION
It is known that lubricants are readily susceptible to decomposition and thus require the addition of various stabilizers and other additives in order to improve performance characteristics. Degradation of the lubricant is primarily due to the action of heat, mechanical stress, especially induced boy shear forces, and chemical reagents, especially atmospheric oxygen. Deterioration of the lubricant results in an increase in total acidity, formation of gums, discoloration and loss of physical properties such as viscosity, loss of potency, polymerization, rancidity and/or unpleasant odor. In the case of lubricating oils used at elevated temperatures, it is particularly desirable for the lubricant to resist oxidation, especially to minimize the formation of sludge and increase in total acidity of the oil, and the consequent lowering of the lubricating ability of the oil and lubricating system in general.
Accordingly, stabilizers are added to the lubricant in order to retard or eliminate degradation, thereby extending the life of the lubricant. For example, U.S. Pat. No. 5,580,482 relates to the stabilization of triglyceride oils subject to oxidative degradation by the addition of either an N,N-disubstituted aminomethyl-1,2,4-triazole or an N,N-disubstituted aminomethylbenzotriazole; a higher alkyl substituted amide of dodecylene succinic acid; a phenolic antioxidant; and an aromatic amine antioxidant. U.S. Pat. No. 4,652,385 discloses that hydrotreated oils are stabilized by addition thereto of a phosphite or diphosphite and a sterically hindered phenolic antioxidant.
It has now been found that incorporating in a hydrotreated or hydrodewaxed oil a certain combination of metal deactivator, metal corrosion inhibitor, sterically hindered phenolic antioxidant, aromatic amine antioxidant leads to surprisingly outstanding performance characteristics.
OBJECTS OF THE INVENTION
One object is to provide a lubricant composition which meets the requirements of oxidative, corrosion and thermal stability, robustness in use and calcium compatibility by incorporating therein the stabilizer package in accordance with the instant invention.
Another object is to provide a process for stabilizing a lubricant by incorporating therein an effective stabilizing amount of the stabilizer mixture in accordance with the instant invention.
DETAILED DISCLOSURE
The present invention pertains to a lubricant composition stabilized against the deleterious effects of heat and oxygen, which composition comprises
(a) a hydrotreated oil or a hydrodewaxed oil;
(b) (i) an effective stabilizing amount of a metal deactivator of the formula (I)
wherein
R
1
is hydrogen or C
1
-C
12
alkyl, and
R
2
and R
3
, each independently of the other, are hydrogen, C
1
-C
20
alkyl, C
3
-C
20
alkenyl, C
5
-C
12
cycloalkyl, C
7
-C
13
aralkyl, C
6
-C
10
aryl, hydroxy, or
R
2
and R
3
, together with the nitrogen to which they are bonded, form a 5-, 6- or 7-membered heterocyclic residue or
R
2
and R
3
is each a residue of the formula (II)
R
4
X[(alkylene)O]
n
(alkylene)— (II),
wherein
X is O, S or NR
4
;
R
4
is hydrogen or C
1
-C
20
alkyl;
alkylene is a C
1
-C
12
alkylene residue; and
n is 0 or an integer from 1 to 6; or
R
2
is as defined above and R
3
is a residue of the formula (III)
or is a residue of the formula (II) as defined above and R
2
is a residue of the formula (IV)
-[alkylene]
n
—N(R
5
)—A—[N(R
5
)
2
]
m
(IV),
wherein m is 0 or 1 and,
when m is 0, A is a residue of the formula (III) and,
when m is 1, A is alkylene or C
6
-C
10
arylene; and
alkylene and n have their above-mentioned meanings; and
R
5
is a residue of the formula (III), as defined above; or
(ii) an effective stabilizing amount of a metal deactivator of the formula (V)
wherein R
2
and R
3
are as defined above;
(c) an effective stabilizing amount of a sterically hindered phenolic antioxidant;
(d) an effective stabilizing amount of an aromatic amine antioxidant;
(e) an effective stabilizing amount of an alkyl phenoxy alkanoic acid of the formula (VI)
wherein R
6
, R
7
, R
8
, R
9
and R
10
are, each independently of the other, hydrogen or C
1
-C
20
alkyl and
Y is a divalent C
1
-C
20
hydrocarbon radical, saturated or unsaturated, selected from the group consisting of
(f) an effective stabilizing amount of an N-acyl sarcosine derivative of the formula (VII)
wherein
the acyl group R
11
—C(═O)— is the residue of a fatty acid having 10 to 20 carbon atoms and X
+
is the hydrogen ion, an alkali metal ion or an ammonium ion.
The compositions of the invention are prepared from hydrotreated or hydrodewaxed lubricating oil. The hydrotreated oils are prepared from vacuum gas oil fractions which have been subjected to a two-stage high-hydrogen-pressure hydrotreating process in the presence of active zeolite catalysts. The disclosures of U.S. Pat. Nos. 3,493,493; 3,562,149; 3,761,388; 3,763,033; 3,764,518; 3,803,027; 3,941,680; and 4,285,804, each herein incorporated by reference, provide various details of such hydrotreating process. In the first stage of a typical hydrotreatment process, the hydrogen pressure is in the vicinity of 20 Mpa and the temperature is maintained at about 390° C., using a fluorided Ni—W catalyst on a silica-alumina support; nitrogen-, sulfur- and oxygen-containing compounds are almost entirely removed from the feedstock, and other effects include a high degree of saturation of aromatics and a high degree of ring scission of the polycyclic intermediates. Lubricating oil fractions from the first stage are dewaxed and subjected to further hydrogen treatment in the presence of a catalyst, for example, Ni—W on a silica aluminum support, at lower temperature than the first stage. Aromatics and olefins are further saturated in this stage. The product oil contains substantially no sulfur or nitrogen, and only trace amounts of aromatics, being substantially entirely composed of saturates including paraffins and cycloparaffins. The compositions can also be used in solvent refined base stocks. Solvent refined oils are defined as Group I oils.
The hydrodewaxed oils are prepared from a hydrocracked, solvent dewaxed lube oil base stock by contacting the base stock with hydrogen in the presence of a multilayered catalyst system. In the first layer, the hydrocracked, solvent dewaxed stock is catalytically dewaxed, using, for example, an aluminosilicate catalyst. In the second layer, the catalytically dewaxed stock is hydrofinished, using, for example, a palladium hydrotreating catalyst having alumina or siliceous matrix. U.S. Pat. No. 4,822,476, herein incorporated by reference, discloses the details of this process.
The resulting hydrotreated lubricant base oils obtained by the processes described above are defined as Group II oils when their viscosity index, an indication of the change in viscosity with temperature, is equal to or below 120. They are defined as Group III oils when their viscosity index is above 120.
The metal deactivator which is used in accordance with the instant invention is an N,N-disubstituted aminomethylbenzotriazole of the formula (I) or an N,N-disubstituted aminomethyl-1,2,4-triazole, or mixtures thereof. To those mixtures or products unsubstituted tolutriazole or benzotriazole may be added. The N,N-disubstituted aminomethylbenzotriazole can be prepared by known methods, as described, for example, in U.S. Pat. No. 4,701,273, such as reacting a benzotriazole with formaldehyde
Fletschinger Michael
Hamblin Peter Collen
Hutchings Miles J.
Lichtenberg Frederick T.
Oshode Adesola O.
Hall Luther A. R.
Howard Jacqueline V.
Stevenson Tyler A.
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