BACKGROUND OF THE INVENTION
U.S. Pat. Nos. 3,617,484 (Nov. 12, 1971), 3,663,427 (Max 16, 1972) and 3,666,657 (May 30, 1972), for example, describe the production of high viscosity index, hydrocracked lube oils and a process of improving the stability of such oils, when exposed to ultraviolet light (especially in the presence of oxygen), by selective extraction of the hydrocracked oil with an aromatic selective solvent (e.g., furfural, phenol, etc.).
It has been discovered that certain "stabilized" hydrocracked oils can be characterized as having a shorter life (to an acid number end point) in the ASTM D-943 test (with an oxidation inhibitor) than do similar unstabilized hydrocracked oils. However, compositions containing such a stabilized oil and an oxidation inhibitor have a better D-943 life (as to an increased acid number of 2.0) than does a similar composition containing a conventional solvent refined oil instead of the stabilized hydrocracked oil.
SUMMARY OF THE INVENTION
Hydrocracked lub oils, especially those having as ASTM viscosity index greater than 85 (typically at least 100) and containing in the range of 3-30 wt. percent aromatics, are especially useful components of petroleum based lubricant compositions and/or functional fluids. Such hydrocracked lubes are especially useful in compositions which also contain an antioxidant, particularly the phenolic types, e.g., ditertiarybutyl paracresol or "DBPC," the amine types, the carbamate types (e.g., antimony or zinc dibutyl carbamate) and the organo thiophosphate types (e.g., zinc dialkyl dithiophosphate), or mixtures of such inhibitors. Such compositions are especially useful in engine oils, refrigeration oils, transmission fluids, turbine oils (especially with DBPC as the major inhibitor), hydraulic oils, textile machinery lubricants, mist lubricants, etc. It can also be useful to add to a hydrocracked paraffinic lube an unhydrorefined naphthenic distillate in amount effective to improve oxidation inhibitor response of the hydrocracked lube.
An especially useful lubricant composition comprises an unhydrorefined naphthenic distillate and a hydrocracked lube oil which has been solvent extracted or hydrorefined to reduce or inhibit sludging on exposure to light and having a viscosity in the range of 80-3,000 SUS at 100°F., and an oxidation inhibitor in amount effective to permit said composition to pass the ASTM D-943 oxidation test (to a total acid number increase of 2.0) for a period of at least 300 hours (more preferred, 500 hours), said amount being less than would be required to permit the same D-943 test performance for a similar composition wherein the hydrocracked lube oil is replaced by an unhydrocracked solvent refined lube of the same viscosity, VGC and viscosity index. In such a composition, where the hydrocracked oil is stabilized by extraction or hydrorefining, said D-943 life will be less than if an unstabilized hydrocracked lube were used. However, the formation of sludge in the D-943 test (which, for example is important in turbine oils) is less for compositions containing the stabilized hydrocracked oil.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel composition, comprising a stabilized hydrocracked lube and an antioxidant, is especially useful in such lubricants as mist oils, textile machinery lubricants, engine oils and hydraulic oils, which contain a high molecular weight polymer of the viscosity index "builder" class, such as polyacrylates, polymethacrylates, dispersant polyacrylates and polymethylacrylates (typically grafted with N-vinyl-2-pyrrolidinone), polystyrenes (e.g., polymethyl styrenes), polyolefins (e.g., polybutenes), or moxtures of two or more of such polymers. The accompanying drawings FIGS. 1 and 2, are typical infra-red absorption spectra (or "scana") of two such commercial polymers, which are especially useful in engine oils to improve the viscosity index thereof. FIG. 3 is an IR scan of a typical engine oil additive "package" of the "DI" or dispersant-inhibitor type.
As articles of commerce, such polymers are well known and readily available but are generally trade secret compositions which require expensive analytical work to completely characterize and can require expensive laboratory work to duplicate. An important laboratory tool for identifying a particular commercial polymer is the infra-red (IR) scan. The scans of all of the FIGS. 1-3 are of commercially available additives and are provided in order to facilitate practice of the embodiment of the present invention wherein the commercial additives can be used.
FIG. 1 is an IR scan of a typical commercial dispersant type polymethacrylate viscosity index "builder," or "improver," marketed by Rohm and Haas as Acryloid 954. This VI builder and other typical builder polymers are described further in pending U.S. application Ser. No. 246,997 (filed Apr. 24, 1972) now U.S. Pat. No. 3,855,135, issued Dec. 17, 1974 [generally, the lower molecular weight materials are preferred in mist lubricants or in "shear stable" engine oils].
FIG. 2 is an IR scan of another commercial VI builder which is marketed by Lubrizol Corporation as "3702" and termed a dispersant type styrene copolymer (note, the IR scan shows a high carbonyl content).
FIG. 3 is an IR scan of Lubrizol 27563 and represents another class of commercial engine oil additive, the Dispersant-Inhibitor package or "DI package." Typically, a DI package can contain a magnesium petroleum sulfonate, an ashless dispersant, and an oxidation inhibitor (e.g., zinc dialkyldithiophosphate). Lubrizol 27563 analyzes 2.40 weight percent zinc, 1.9% magnesium, 2.15% phosphorous, 0.17% nitrogen and 5.0% sulfur.
The following Table I presents typical properties of stabilized hydrocracked oils which can be used in practice of the present invention.
TABLE I ______________________________________ Properties of Hydrocracked Oils* Aniline Viscosity ASTM Gravity Wt.% Point (SUS, 100°F) VI API Aromatics °F. ______________________________________ 100 103 34.2 12 220 200 107 33.3 11 235 500 107 31.5 13 250 ______________________________________ *All oils dewaxed to a 0°F. pour point by chilling in a solvent, and stabilizing by extraction with furfural.
In general, such hydrocracked and stabilized hydrocracked oils (of high VI and low pour point) can be substituted in whole or in part for the hydrorefined paraffinic oil or solvent refined paraffinic lube component in the compositions (or process where applicable) of U.S. pat. No. 3,502,567 of Ivor W. Mills and Glenn R. Dimeler, issued Mar. 24, 1970, for example. In such compositions the oxidation inhibitor concentration can be reduced when 85-100% of the solvent refined lube is replaced by the stabilized hydrocracked oil.
For example, in a mist lubricant formulation which contains a solvent refined paraffinic lube, the partial or whole substitution of a hydrocracked (preferably, a stabilized hydrocracked) lube permits the use of a lower concentration of the polymeric additive for a given degree of stray fog. This provides improved reclassification performance (for a given degree of stray fog) in the composition containing the hydrocracked lube. Alternatively, a lower molecular weight polymer can be used in the composition containing the hydrocracked lube.
In hydraulic oils, whether soap or polymer thickened, a preferred oil contains mainly DBPC (e.g., 0.5 weight percent) as the antioxidant and a minor amount (e.g., 0.01-0.1% Zn) of zinc dialkyl dithiophosphate to impart antiwear properties.
In turbine oils, the use of a stabilized hydrocracked oil in combination with an ashless or virtually ashless inhibitor improves the performance in test where sludging is measured (as in Mil-L-17672B). In engine oils, the composition containing an antioxidant (preferably zinc dialkyl dithiophosphate at levels imparting 0.1-3% Zn in the final composition) and a stabilized hydrocracked oil provides better performance in the Sequence IIIc test. Also, when tested in a natural gas burning engine, the composition containing the stabilized hydrocracked oil is superior.
As an additional component (to hydrorefined oils and unhydrorefined oils) in textile oils or refrigeration oils, high viscosity index hydrocracked oils and/or hydrogenated polyolefin oils (e.g., polybutene in the C16 -C40 range) can be used. The polyolefin or hydrocracked oil can be partially or fully hydrogenated.
The following automatic transmission fluid is prepared by blending each of the components with stirring at room temperature:
88.8 wt. % of a blend of "furfural stabilized" hydrocracked paraffinic oil having a 0°F. pour point, a viscosity of 140 SUS at 100°F. and 105 ASTM VI;
0.5 wt. % of dilauryl thiodipropionate (antioxidant);
0.2 wt. % of "Naugatuck 438," manufactured by Uniroyal, an amine antioxidant;
0.3 wt. % "Lubrizol 1097" (zinc dialkyl dithiophosphate) (an antioxidant and wear inhibitor);
0.5 wt. % "Amoco 121" (barium alkyldiphosphonate) (a detergent);
0.3 wt. % overbased magnesium petroleum sulfonate having a base number of 300;
0.1 wt. % tricresylphosphate;
3.0 wt. % a refined petroleum oil containing 95% aromatics as a seal swell agent;
10 p.p.m. dimethyl silicone defoamer having a viscosity of 60,000 cs at 68°F.;
3.0 wt. % of synthetic sulfurized sperm (see Canadian Ser. No. 134,156) and
3,75 wt. % dispersant polymethacrylate viscosity index improver which is a copolymer of laurylmethacrylate and methylmethacrylate having grafted thereon n-vinyl-2-pyrrolidinone.
This automatic transmission fluid provides superior performance (compared to a similar formulation containing solvent refined lube of the same viscosity) in the General Motors T-12 Powerglide Low Energy Transmission Cycling Test.
A limited slip differential fluid is prepared by blending the following components at room temperature:
70.0 vol. % furfural stabilized hydrocracked oil having a viscosity of 500 SUS at 100°F. VI of;
21.6 vol. % unstabilized hydrocracked bright stock (2,500 SUS at 100°F.);
0.5 vol. % Friedel-Crafts condensation products of chlorinated paraffinic wax with phenol (pour depressant)
7.4 vol. % an chlorinated pressure additive comprising a mixture of zinc phosphorodithioate and cholorinated hydrocarbons containing 3% Zn, 3% P, 16.5% Cl and 16% S;
0.5 vol. % di-n-butyl tin dilaurate; and
10 p.p.m. dimethyl silicone defoamer having a viscosity of 60,000 cs at 68°F.
The high traction components of U.S. Pat. No. 3,608,385 of Irl N. Duling et al, issued Sept. 28, 1971, can be added to this fluid to increase the traction coefficient thereof.
A turbine oil is prepared by blending each of the following components (in parts by weight) with stirring:
99.4 furfural stabilized hydrocracked oil having an SUS viscosity of 150 at 100°F.;
0.2 enjay Paraflow 149 (pour depressant); and
0.4 ditertiary butyl paracresol.
Enjay Paraflow 149 is a Friedel-Crafts reaction product of chlorinated biphenyl.
This oil passes all turbine requirements for low sludge except for M-L-17642B. If 0.75 parts Vanderbuilt Vanalube 664 is used instead of the DBPC, the formulation can pass M-L-1762B.
This oil passes over 2000 hours of the D-943 test. A similar turbine oil containing a solvent refined paraffinic lube failed after 1500 hours of the D-943 test.
Vanalube 664 is a mixture of DBPC and amine type oxidation inhibitors and also includes a small amount of Butyl Zinate (zinc di-n-butyl carbamate).
An expecially high quality 10W-40 engine oil is made by blending the following (in parts by weight) with stirring:
42.2 solvent refined paraffinic oil viscosity of 110 SUS at 100°F., ASTM VI of 104;
42.2 solvent refined paraffinic oil of 210 SUS at 100°F., ASTM VI of 103;
9.0 Acryloid 954, VI builder; and
6.6 Lubrizol 4446. Lubrizol 4446 is the more common commercial designation of the product previously referred to as Lubrizol 27563 and further identified by the IR scan of FIG. 3 herein. Properties of this oil are shown in Table II below.
TABLE II ______________________________________ ASTM Test Characteristics Method Results ______________________________________ No. Viscosity, cP/0°F. D2602 2100 Viscosity, SUS/100°F. D2161 447 No. Viscosity, SUS/210°F. D2161 83.5 Viscosity Index D2270 105 Viscosity, cSt/210°F. D445 16.40 Gravity, °API D287 30.0 Flash COC°F. D92 410 Pour, °F. D97 -45 Color D1500 14.5 pH 7.8 Total Acid No., mgKOH/g D664 3.6 Total Base No., mgKOH/g D664 6.9 Sulfur, % D129 0.44 Conradson Carbon % D189 1.2 Foam, Tend/Stab D892 Sequence I, ml 5/0 Sequence II, ml 20/0 Sequence III, ml 5/0 No. Appearance Visual Bright Magnesium, % 0.146 No. Zinc, % 0.185 Phosphorous, % D1091 0.165 Sulfated Ash, % D874 1.0 ______________________________________ SAE 10W-40 API Service Classification SE, CB
When 110 and 210 SUS stabilized hydrocracked oils are substituted for 90-100% of the solvent refined oils, the zinc dialkyl dithiophosphate content of the oil can be reduced by 20% (e.g., 0.18% Zn to 0.14% Zn in final oil) and the oil will perform at least as well in the Sequence IIIc test. Furthermore, the Acryloid 954 can be reduced to 8.5% and the oil will still perform at least as well as is indicated in Table II.
Preferably, with the stabilized hydrocracked oil, engine oils can contain 0.07-0.18% Zn (as zinc dithiophosphate), depending on desired performance.
The VI builder of FIG. 2 can be substituted in whole or in part for the Acryloid 942.
The oxidation stability of hydrocracked paraffinic lube oils is improved by the addition of small amounts (up to 15%) of unhydrorefined naphthenic distillate. Such improvement is observed in the rotary bomb oxidation test (RBOT)**as follows
Vol. % of 100 SUS (at 100°F.) naphthenic distillate* 0 10 15 ______________________________________ RBOT, 300°F. minutes hydrocracked lube oil 205 264 257 Solvent refined lube oil 190 160 -- ______________________________________ *Naphthenic acid-free (i.e., total acid number or "neutralization number" less than 0.2 mg. KOH/g). ** ASTM D2272.
The test oils also contain 1.25% Vanlube 664, antioxidant and rust inhibitor package. The data indicate that the naphthenic distillate improves the oxidation inhibitor response of hydrocracked lubes, while reducing the oxidation inhibitor response of the conventional solvent refined lubes. However, the addition of hydrorefined naphthenic oils to conventional solvent refined lubes does improve inhibitor response.
As used herein, the term "hydrocracked paraffinic lube" refers to a hydrocracked oil having a viscosity-gravity constant no greater than 0.819. Naphthenic (including relatively naphthenic oils) have a VGC in the range of 0.820 to 0.899, the more preferred naphthenic oils being in the range of 0.840-0.899. The hydrocracked paraffinic oils can be obtained by hydrocracking a naphthenic charge stock since hydrocracking can cause reduction of the VGC.
Motor lubricants containing hydrocracked lubes (compared to conventional solvent refined lubes) can also provide decreased consumption and, thus, greater oil economy. For example, a 5W-40 motor oil having excellent oil economy in both suburban and turnpike service in passenger automobiles was made according to the following formulation:
Component Volume % ______________________________________ Hydrocracked 110 SUS (at 100°F.) lube 81.8 Zinc dialkyl dithiophosphate in carr- ier (Amoco 5959 containing 9.0% Zn) 0.6 VI improver (Acryloid 954) 11.5 Motor oil package, Lubrizol 4441, containing a detergent, antioxidant and dispersant and analyzing S, Mg, Zn, P and N 6.1 ______________________________________
Table III herein presents typical data of commercially available naphthenic distillate oils which can be blended with a hydrocracked lube to provide improved oxidation stability (including improved response to additives which are oxidation inhibitors).
TABLE III __________________________________________________________________________ TYPICAL DATA COMMERCIALLY AVAILABLE NAPHTHENIC DISTILLATE OILS ASTM ASTM Property Designation Oil A Oil No. 3 Oil B Oil C Oil D Oil E Oil F Oil Oil __________________________________________________________________________ H Viscosity, SUS at 100°F D-2161-66 108 156 208 310 515 780 1276 2525 5945 Viscosity, SUS at 210°F D-2161-66 38.2 41 43.2 46.8 52.4 58.8 68 87.2 135 API Gravity at 60°F D- 287-67 22.2 22.1 21.0 20.1 19.6 19.1 18.4 17.6 17.3 Specific Gravity at 60°F D-1250-56 .9206 .9194 .9279 .9334 .9365 .9396 .9440 .9490 .9509 Flash Point, COC, F D- 92-66 320 330 345 355 380 390 405 430 495 Volatility 22 hrs. at 225 Wt. % D- 972-56 7.58 5.96 5.40 4.35 3.08 2.11 1.67 0.16 0.02 Pour Point, F D- 97-66 -45 -35 -30 -15 -10 -5 0 +10 +20 Color, ASTM D-1500 D-1500-64 1.25 1.75 1.75 2.0 2.0 2.5 3.0 3.5 5.75 Molecular Weight D-2502-67 295 325 325 345 355 370 380 395 450 Viscosity-Gravity Constant D-2501-67 0.884 0.878 0.884 0.887 0.885 0.885 0.885 0.889 0.884 Refractive Index D20 D-1747-62 1.5081 1.5079 1.5121 1.5160 1.5167 1.5190 1.5210 1.5222 1.5250 Refractivity Intercept D-2159-64 1.0502 1.0479 1.0500 1.0511 1.0503 1.0510 1.0508 1.0495 1.0495 Carbon Type Analysis D-2140-62 Aromatic Carbon Atoms, Ca % -- 21 20 21 22 21 22 22 21 20 Naphthenic Carbon Atoms Cn % -- 37 36 37 36 37 36 36 39 38 Paraffinic Carbon Atoms Cp % -- 42 44 42 42 42 42 46 40 42 Molecular Type Analysis (Clay Gel) D-2007-56T Asphaltenes, Wt. % -- 0 0 0 0 0 0 0 0 0 Polar Compounds, Wt.% -- 1.1 1.2 1.8 2.0 2.5 2.7 3.0 2.7 4.2 Aromatics, Wt.% -- 43.0 41.7 44.0 44.0 43.8 43.6 44.0 44.8 44.7 Total Aromatics % -- 44.1 42.9 45.8 46.0 46.3 46.3 47.0 47.5 48.9 Saturates, Wt. % -- 55.9 57.1 54.2 54.0 53.7 53.7 53.0 52.5 51.1 Analine Point, F D- 611-64 145 156 152 153 156 162 166 172 183 ASTM Type D-2226-69 103 103 103 103 103 103 103 103 103 __________________________________________________________________________ Oils, B, C, E and F are blends of oils A and G