US2280450A - Lubricant - Google Patents

Description

Patented Apr. 21, 1942 UlTE LUBBICAN T Raymond Renter, Mediord Lakes, N. J., assignor to The Atlantic Refining Company, Philadelphia, Pa., a. corporation of Pennsylvania No Drawing.

7 Claims.

This invention relates to the treatment of hydrocarbon products such as mineral oils to im- Appiication February 20, 1940, Serial N0. 319,840

prove their characteristics, and particularly to the addition to petroleum lubricating oils of certain materials which improve their ability to resist the deteriorating efiect of oxidation and their ability to lubricate bearing surfaces which are subjected to extreme pressures such as are now commonly encountered in the newer types of machinery.

Moderately refined oils, such as motor oils and other moderately refined lubricating oils and moderately refined turbine oils normally used under conditions of exposure to oxidation in the presence of metals, oxidize, giving rise to sludge and/or acidic oxidation products frequently-corrosive to the metals which they encounter in use, as for example bearing metals in automotive use. and copper and-copper alloys in turbine use. It has now been found that stabilization of these oils against such oxidation effects may be conveniently accomplished .by addition to the oils of certain materials which substantially retard the oxidation of the oils, whether or not metal is present, and which apparently have-the ability to inhibit the catalytic effect of metals in promoting oxidation reactions and thus prevent the formation of sludge and/or acidic constituents and the like under normal conditions of use.

Recent changes in automotive engine design, tending toward higher bearing pressures, higher rotative speeds, higher engine temperatures, and

the like, have occasioned departure from the use of the usual bearing metals such as babbitt. The newer bearing metals are of different nature, than those less recently developed and while harder, are in general more susceptible to destructive agencies of a corrosive nature. Typical of these newer bearings are those composed of a cadmium-silver alloy supported upon a steel back,

fining lubricant oils for automotive use. The demand for oils having lesser changes in viscosity with temperature change; i. e., higher viscosity index (frequently designated as V. 1.), has been met by refining lubricants intended for motor oils by certain solvent refining or solvent extraction processes, wherein advantage is taken of the selective solvent power for hydrocarbons of various types which is possessed by certain liquid reagents, for example, dichlorodiethylether, cresylic acid, phenol, chloraniline, chlorophenol, phenetidine, benzyl alcohol, nitrobenzene, benzonitrile, furfural, aniline, benzyl acetate, liquid sulphur dioxide, mixtures of liquid sulphur dioxide or aniline with benzol, and the like. Those solvent refining processes are designed to concentrate in the ,desired lubricant fraction those compounds of aI parafilnic nature possessed of the ability to suffer only a small change of viscosity with change of temperature, and to reject the compounds of naphthenic" nature which do suffer such change of viscosity to such a marked degree. These refining processes have provided a supply of oil of quite desirable general characteristics definitely far superior to any oil previously produced from mixed base or asphaltic crudes, and superior to a like, though lesser, degree over oils previously produced from paraffin base crudes.

It has been found that the solvent refined motor oils referred to above are definitely corrosive to the newer bearing metals referred to above under extreme conditions of automotive use, due to oxidation during use, sometimes resulting in bearing failure after only a few thousand miles of driving. Dimculties are frequently encountered due to bearing corrosion in automotive equipment operated at sustained high speeds of the order of to M. P. H., or under other conditions conducive to high crankcase temperatures of the order of 275 F. or higher. It is further known that the same reaction, viz., corrosion of alloy bearing metals such as cadmium-silver, also occurs in good paraiiinic base oils which have" not been subjected to solvent refining. The higher the V. I. of the lubricating oil, the more pronounced is the tendency to corrosion of the kind referred to above. Generally speaking, the prob- 'lem is encountered in oils having a V. I. of or and the like, there is a similar tendency toward the use of high unit pressures of a degree which are near or beyond the limit at which mineral oils, alone, will maintain effective lubrication. This invention is therefore specifically concerned with the production of lubricants capable of withstanding the high unit loadings which occur in such instances. Such lubricants are generally spoken of as extreme pressure lubricants.

Extreme pressure lubricants are normally produced by adding to a hydrocarbon lubricant a small amount of some characterizing substance which enables it to maintain a lubricant film unruptured under conditions which would cause the breakdown of a film formed of oil alone. Such additive substances arespoken of as E. P. (extreme pressure) bases, or E. P. ingredients. Many commonly used E. P. bases are composed of sul phur dissolved in mineral oil, sulphurized vegetable or animal oils, chlorinated compounds, metallic soaps, and the like. This invention is specifically concerned with the use, as E. P. characterizing ingredients, of compounds new and novel for this purpose, and not heretofore so used or known to be useful for this purpose.

It isan object of this invention to provide an extreme pressure lubricant, which lubricant is superior to lubricants of this class heretofore commonly known, particularly in load-carrying capacity, stability, and maintenance of extreme pressure lubricating properties under sustained conditions of high loading. It is an object of this invention to prepare novel and valuable ingredients and to combine them with hydrocarbon lubricant oils to produce lubricants having high load bearing capabilities, to prepare such ingredients which have good characteristics of stability, which are less corrosive, and which impart a greater influence when present in much smaller amounts than are required with extreme pressure ingredients now commercially available. Further objects are the provision of methods of making the ingredient or ingredients, methods of prepar- -ing lubricants containing these novel characterizing ingredients, and methods of lubrication making use of the lubricants so produced.

It is an important object of this invention to provide means for satisfactorily inhibiting or preventing corrosion from taking place to a serious degree particularly in oils of relatively high viscosity index. It is also an object of this invention to alter or modify a highly refined motor oil, normally corrosive, by the use of an additive ingredient capable of substantially inhibiting this corrosion. It is a further object of this invention to provide a substantially noncorrosive motor oil of high V. I. Still another object of this invention is to provide an additive reagent or ingredient capable of inhibiting the corrosive properties of these oils. The production of solvent refined oils of low corrosivepropv erties under conditions of automotive use is a major object of this invention, as well as the method of production of such oils which combine a relatively high viscosity index with a relatively low tendency to produce such corrosion.

A further object of this invention is the provision of lubricating oils, particularly oils for use in internal combustion engines, which do not deposit gummy or resinous films or lacquers" upon pistons, rings, valves, and cylinderwalls of engines, and especially those operated at relatively high temperatures and/or for long periods of time.

I have found that hydrocarbon oils of the aasaaeo classes defined above can be stabilized against the formation of acidic and/or corrosive and/or sludge bodies by the addition to said oils of a relatively small amount of a substantially stable, oil-soluble, water-insoluble reaction product of tricresyl phosphite and octyl phenoxyethanol. I have also found that novel lubricants having extreme pressure lubricating characteristics can be produced by adding to oil a suflicient quantity of said reaction product.

The above mentioned substantially stable oilsoluble, water-insoluble reaction product is adapted, as I have discovered, to be added directly to or dissolved in a hydrocarbon oil for the purpose of inhibiting or eliminating the normal tendency of said oil to corrode the metal bearings and parts hereinbefore mentioned, to stabilize said oil against the accelerating action of metals on the deteriorating effects of oxidation reactions under normal conditions of use and/or handling and/or storage and to increase the ability of the oil to withstand high unit loadings. By substantially stable, I mean stable under the normal conditions of use and/or handling and/or storage to which this corrosion inhibitor and oxidation inhibitor is ordinarily subjected, after manufacture, either before it is added to the hydrocarbon oil to be stabilized or after it is added to such an oil.

In preparing the reaction product to be employed in accordance with my invention, I may admix the tricresyl phosphite with the octyl phenoxyethanol and thereafter bring the mixture to a temperature sufi'icient to cause reaction of the ingredients, whereby there is introduced into the tricresyl phosphite at least one octyl phenoxyethanol group. The moi ratio of tricresyl phosphite to octyl phenoxyethanol employed may vary from about 1:1 to about 1:2.5, and is preferably of the order of about 1:1.4. The admixture of ingredients may be heated at atmospheric pressure under a reflux condenser to a temperature sufficient to effect reaction, for example, temperatures of the order of from about 200 F. to about 500 F., and'the resulting oil-soluble, water-insoluble reaction product may be separated from the byproducts of the reaction by distillation under reduced pressure, or by recrystallization from a suitable solvent, or by washing with a solvent having selective solvent power for either the reaction product or the undesirable byproducts. Preferably, however, the reaction between the ingredients is carried on at elevated temperatures of the order of from about 200 F. to about 350 F., under reduced pressures of the order of 10 m. m. or less. Depending upon the ratio of tricresyl phosphite to octyl phenoxyethanol employed, and upon the temperature and time of reaction, at least one and in some instances two octyl phenoxyethanol groups may be introduced into the tricresyl phosphite. The reaction product so produced may be re -garded as complex ester of phosphorous acid tion, air blowing, or by washing with a suitable solvent.

The reaction product produced in accordance with my invention may be added to hydrocarbon oils in varying amounts, depending upon the qualities it is desired to impart to the oil. For example, in order to inhibit oxidation of hydrocarbon oils such as lubricating oil, turbine oil, or electrical insulating oil suchas transformer or cable oil, I may incorporate in the oil from about 0.05% to about 0.5% of my reaction product. In the case of lubricating oils for internal combustion engines, quantities of reaction product of the order of 0.1% to about 0.7% will inhibit the formation of color bodies and acidity, and will inhibit corrosion of bearing metals such as cadmium-silver and copper-lead alloys. tion product, when employed in quantities of the order of 0.4% to about 0.7% will inhibit the formation of sludge, resinous bodies, or lacquers, and will impart to the oils a moderate degree of film strength or extreme pressure characteristics. Where a considerable degree of improvement in My reacfilm strength or extreme pressure characteristics is required, my product may be employed in amounts of the order of 1% to 2%, or more. In those cases where it is desirable, from an economic point of view, to employ only sufficient quantities of my-reaction product to inhibit oxidation of the oil, and to obtain a high degree of film strength by the addition of other agents, I may add to the oil, for example, 0.4% of my reaction product and 0.6% of a film strength agent such as tricresyl phosphate. Other film strength agents, of course, may be employed in lieu of or in addition to tricresyl phosphate, and the quantities of such agents may be varied, as desired.

My invention may be further illustrated by the following examples, which, however, are not intended as limiting the scope thereof.

1 mol of tricresyl pho phite and 1.4 mols of octyl phenoxyethanol were admixed and introduced into a vacuum still. Heat was applied to the still and the admixture was brought to a temperature of about 150 F., whereupon the pressure within the still was reduced to about 5 m. m. by means of a' vacuum pump connected to the condensing system associated with the still. The admixture was then heated, under the reduced pressure aforesaid, to a temperature of the order of about 240 F., at which temperature reaction between the tricresyl phosphite and the octyl phenoxyethanol was initiated. The temperature of the reaction mixture was then progressively raised to about 320 F., and the mixture was maintained at such temperature until substantially all of the cresol liberated during the reaction (about 1 mol of cresol or 30.7% by weight of the tricresyl phosphite initially charged) has been distilled from the reaction mixture. Traces of residual cresol may be removed from the heated reaction mixture, while under reduced pressure, by bubbling a small quantity of air or inert gas such as carbon dioxide or nitrogen through the reaction mixture. The cresol distilled from the mixture may be condensed and disposed of as desired. The reaction product obtained by the above process appears to be a complex ester of phosphorous acid containing at, least one octyl phenoxyethanol group, and possibly a small amount of unreacted octyl phenoxyethanol.

The inhibiting effect of the above describedreaction product uponthe formation of sludge due to oxidation of lubricating oil is illustrated 76 by the data presented in the following table. The blank oil and the 011 containing various percentages of my reaction product were subjected to an oxidation test which comprised heat g a cc. sample of the oil at a temperatu e of 340 F. for a period of 96 hours,while bubbling air through the heated sample at a rate of 3 liters per hour. The insoluble sludge was separated from the oil, washed with a solvent to remove adhering oil, and dried to constant weight. The amount of sludge is reported as milligrams per 10 grams of oil. The oil employed was a solvent refined S. A. E. 20 motor oil having a Saybolt universal viscosity of 312 seconds at 100 F., and

Blank oil +04% by vol. of reaction product Blank oil +0.7% by vol. of reactionproduct The inhibiting effect. of my reaction product upon change of color of the oil subjected to the oxidation test above set forth is shown in the following table. The blank oil and the oil containing 0.4% by weight of my reaction product were examined for color change at intervals of one hour until the color of the blank oil became undeterminable- A. S. '1. M. color hours heating Oil composition Blank oil 2y; 5 8 8 Black. Blank oil 0.4% by vol. of reaction product 2% 23 1 2% 3 3% To demonstrate the inhibiting action of my reaction product upon corrosion of bearing metals by refined lubricating oil, the following data is presented. The test utilized comprised subloss in weight, due to corrosion, is reported in milligrams. The oil employed in this test was a selective solvent refined oil having a Saybolt universal viscosity of 312 seconds at 100 F., and and A. P. I. gravity of 293.

Weight loss of bearings in mgs. Oil composition Cadmium- Coppersilver lead Blank 011.: e0 27 Blank oil+0.4% by vol. of reaction product 0. 3 4. 7

The efiectiveness of my reaction product in increasing the film strength or load-bearing capacity of lubricating oil is illustrated by the results tabulated below. The blank oil and the oils containing various percentages of' my reaction product were tested in an Almen extreme pressure lubricant testing machine operated at" 200 R. P. M. The pressures are expressed as lbs./sq. in, projected bearing area sustained before seizure of the test bearing. The lubricating oil employed was the same as used in the preceding test for corrosion inhibition.

Oil composition 'igj fi fi Blank oil 4, 000 Blank oil+0.4% by vol. of reaction product 12, 000 Blank oil+0.7% by vol. of reaction product 17, 000

Oil-+0.47 reacgfii tion pr zzduct Properties 3 (used), hours A. P. I. gravity degrees" 28.9 23.6 23.3 S. U. v|s./100 F.

inches 325 395 511 697 785 361 405 486 617 S. U. vis./210 F.

inches- 53 76 70 Viscosity index 93 93 98 Neut. number (mgs.

OH/gnL}. .02 3.85 G.39.4510.3 1.9 3.3 5.9 9.15v Carbon residue .01 .58 1.17 1.57 1.97 .43 .68 1.10 1.67 Asphaltenes- .00 .09 .27 .35 .72.02.05 .13 .24 Sediment .00 .11 .19 .53 1.07 .06 .07 .06 .51

loss in mgs 4,861 2,832

The results obtained in the Lauson engine test are tabulated below. The Lauson engine was run for 24 hours at 1765 R. P. M., at a ,crankcase oil temperature of 310 F., and the test oils were examined at the end of the 24 hour run.

'1 0'1 l 1 reac ion I mpefl'ms (new) (used) product P. I. gravity "degrees" 28.9 27. 7 28.5 S. U. VlS./100 F -inches 325 381 326 S. U. vis./210 F... do 53 57 55 Viscosity index 93 99 106 Neut. number (mgs .02 2.1 .40 Carbon residue 01 47 Asphaltenes 00 .37 12 Sediment 00 17 02 Resin deposit on pistonhmilligramsfl 1, 925 263 Piston ring weight loss .do 107 Bearing weight loss do From the results of the'tests above set forth, it will be apparent that in all respects the oils containing small amounts of my reaction product are markedly superior to oils to which no reaction product has been added.

The reaction product of my invention may be utilized not only as an inhibitor or film strength agent for hydrocarbon oils, but also for similar purposes in other products such as thickenedoils or greases, cutting oils, petrolatums, waxes, animal and vegetable oils, or mixtures thereof with hydrocarbon oils.

What I claim is:

1. A hydrocarbon oil composition comprising a relatively large proportion of a refined hydro-' carbon oil normally tending to. deteriorate by oxidation under normal conditions of use and in intimate admixture therewith a relatively small amount sulficient to inhibit such deterioration, of an oil soluble, water-insoluble reaction product of tricresyl phosphite and octyl phenoxyethanol.

2. A lubricant comprising hydrocarbon lubricating oil and a small amount of an oil-soluble,-

4. A lubricant comprising hydrocarbon lubrieating oil and from about 0.05% to about 2.0% ofan oil-soluble, water-insoluble reaction product of tricresyl phosphite and octyl phenoxyethanol. 5. A lubricant comprising hydrocarbon lubricating oil and from about 0.4% to about 0.7% of an oil-soluble, water fnsoluble reaction product of tricresyl phosphite and octyl phenoxyethanol.

6. A lubricant'comprising hydrocarbon lubricating oil and a small amount of an oil-soluble, water-insoluble reaction product of tricresyl phosphite and octyl phenox'yethanol, and a small amount of tricresyl phosphate.

7. The method of lubricating bearing'surfaces, which comprises maintaining between bearing surfaces, one of which is an alloy selected from the class consisting of cadmium-silver, cadmiumnickel, cadmium-zinc, cadmium-zinc-lead-antimony, copper-lead, copper-lead-tin, and high lead babbitts, a film of lubricating oil which initially produces an effective lubricating action but which would normally tend to corrode the aforesaid alloy, and maintaining the effectiveness of the lubricating oil by incorporating therein a small amount, sufficient to substantially retard corrosion, of an oil-soluble, water-insoluble reaction product oi tricresyl phosphite and octyl phenoxyethanol.

RAYMOND REUTER.