US2353558A - Addition agent for lubricating oil and method of making same - Google Patents

Description

Patented July 11, 944

ADDITION AGENT FOR LUBRIOATING OIL AND METHOD OF MAKING SAME Felix C. Glemski, Philadelphia. Pa.. aseignor to The Atlantic Refining Company, Philadelphia, Pa... a corporation of Pennsylvania No Drawing. Original application February 20,

1940, Serial No. 319,841. Divided and this application December 7, 1940, Serial No. 389,130

4 Claims. (01. 260-461) This invention relates to the treatment of hydrocarbon products such as mineral oils to improve their characteristics, and particularly'to the addition to petroleumfilubricating. oils of certain materials which'improve their ability to resist the deteriorating eflectof 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.

This application is a division of my application Serial No. 319,841, filed February 20, 1940, en-

titled Lubricant.

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 or acidic oxidation products, or a combination thereof as the case may be, 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 These changes in engine design have been concurrent with marked advances in methods of refining lubricant oils for automotive use. demand for oils having lesser changes in viscosity with temperature change; i. e., higher viscosity index (frequently designated as V. I.), 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, pheoxidation of the oils, whether or not metal is present, and which apparently have the ability to inhibit the catalytic effectof metals in promoting oxidation reactions and thus prevent the formation of sludge or acidic constituents and the like, or a combination thereof as the case may be, 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. Thenewer bearing metals are of diflerent 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, which are now widely installed in certain makes of automobiles. Others of these relatively new bearing metals which may, be mentioned are copper-lead alloys, copper-lead-tin alloys, cadmium-nickel alloys, cadmium-zinc alloys, cadmium-zinc alloys modified by the presence of lead, antimony, or both,and a general class of alloys consisting mainly of lead and hardened with calcium, barium, potassium, antimony, and the like, known generically as high lead babbittsi iii) netidine, benzyl alcohol, nitrobenzene, benzonitrile, furfural, aniline, benzyl acetate, liquid sulphur dioxide, mixtures of liquid sulphurdioxide or aniline with benzol, and the like. Those solvent refining processes are designed to concentrate in the desired lubricant fraction those compounds of a paraillnic 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, degr'ee over oils previously produced from paraflln 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. Difliculties are frequently encountered due to hearing' 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 bearingmetals such as cadmiumthe problem is encountered in oils having a V. I.

of or higher, particularly at elevated temperatures of engine operation.

Furthermore, the present trend in automotive design toward lower body styles, rapid accelera- The ' tion, and the use of hypoid gears has increased theunit loadi'ngs'qn rear axles. In some cases the unit pressures encountered become great enough to rupture the oil film of ordinary mineral oil lubricants, with consequent metal to metal contact. In other lines of power transmission 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 eflective 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 prothread 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 fllm formed of oil. alone.

Such additive substances are spoken of as E. P. (extreme pressure) bases, or- E. P. ingredients. Many commonly used E. P. bases are composed oi sulphur-dissolved in mineral oil, sulphurized vegetable or animal oils, chlorinated compounds, metallic soaps, and the like. Thisinventi'on is specifically concerned with the use, as E. P. characterizlng ingredients, of compounds new and novel for this purpose, and not heretofore so used or known to be useful for this purpose.

It is an 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 preparing 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 oi this invention to alter or modify a highly refined motor oil, normally corrosiv bythe use of an additive ingredient capable oi' substantially inhibiting this corrosion. It is a nirther'obiect of this invention to provide a substantially non-corrosive motor oil tion is to provide an additive. reagent or ingredient capable-of inhibiting the corrosive propas trimethyl phosphite,

assaess l in internal combustion engines, which do not deposit gummy or resinous films or "lacquers" upon pistons, rings, valves, and cylinder walls of engines, and especially those operated at relatively high temperatures or for long periods of time, or a combination thereof as the case may be.

I have found that hydrocarbon oils of the classes defined above can be stabilized against the formation of acidic or corrosive or sludge bodies, or a combination thereof as the case may be, by the addition to said oils of a relatively small amount of a substantially stable, oil-soluble, water-insoluble reaction product of an ester of phosphorous acid and a relatively high boiling aliphatic alcohol. 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. Among the esters of phosphorous acid which may be suitably employed in the production of my reaction products are the aryl phosphites such as triphenyl phosphite, trinaphthyl phosphite, trianthryl phosphite; the alkylated aryl phosphites such as the tricresyl phosphites, trixylenyl phosphites, triethyl phenyl phosphites, tripropyl phenyl phosphites, tributyl phenyl phosphites, trlamyl phenyl phosphites, and the isomers and higher homophosphites in the production oimy reaction products, I may also utilize th alkyl phosphites such iethyl phosphite, tributyl phosphite, and triamyl phosphite. Mixed alkyl-aryl phosphites and hydro-aromatic phosphites, as well as aryl or alkyl mono and diphosphites and the esters of hypophosphorous, pyrophosphorous, and thiophosphorous acids may also be employed.

The relatively high boiling aliphatic alcohols which I utilize in theipreparation of'my reaction 'of highv. I. Still another object of this invenerties of these oils. The production of solvent products include the Imono and polyhydric alcohols, preferably those having boiling points above about 200 C. Representative examples of such compounds are octyl alcohol, nonyl alcohol, decyl alcohol, undecyl or lauryl alcohol, oleyl alcohol, stearyl alcohol, ceryl alcohol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, and glycerol. I may likewise employ high boiling ether alcohols such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and the like.

The above mentioned substantially stable oilsoluble, water-insoluble reaction products are said oils against the accelerating action of metals. on the deteriorating effects or oxidationreactions under normal conditions oi use or handling or in reparing the reaction product to be em-' played in accordance with my invention, 1 pro for to a the ester ofphosphorous acid with the relatively high boiling alcohol and thereafter bring the mixture to a temperature suficient to cause reaction of the ingredients, whereby there is introduced into the ester of phosphorous acid at least one high boiling alcohol group. The mol ratio of ester to alcohol employed may vary from 1:1 to 1:25, and is preferably of the order of about 121.4. The admixture of ester and alcohol may be heated at atmospheric pressure under a reflux condenser to a temperature suillcient to eflect reaction, for example, temperatures oi. the order of from 200 F. to 500 F., and the re-,

sulting oil-soluble, water-insoluble reaction product may be separated from the byproducts of the reaction by distillation under reduced pressure, or by recrystallization from asuitable solvent, or by washing with a solvent having selective solvent power for either the reaction product or the undesirable byproducts. Or, if both the ester I and the alcohol are relatively high boiling, the

reaction may be carried on at elevated temperatures of the order ofirom 200 F. to 350 F., under reduced pressures of the order of m. m. or less. On the other hand, if the ester is relatively low boiling and the alcohol is relatively high boiling, the reaction may be carried on at elevated temperature and under a suitable superatmospheric pressure. Depending upon the ratio of ester to alcohol employed, and upon the temperature and time of reaction, at least one and in some instances two alcoholic groups may be introduced into the ester'oi' phosphorous acid. The reaction products so produced may be regarded as complex esters of phosphorous acid which may or may not contain unreacted high boiling alcohol. Such reaction products have a wider range or utility and eflectiveness as inhibitors and the like than the simple esters from which they are prepared.

Alternatively, my reaction product may be produced directly in hydrocarbon. oil by adding thereto suitable quantities of ester and high boiling alcohol, and then heating the mixture to a temperature suflicient to cause the reaction of the ester with the. alcohol, undesirable byproducts of the reaction being removed by distillation or by washing with a suitable solvent.

The reaction products produced in accordance with my invention maybe added to hydrocarbon oils invarying 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 such as transformer or cable 011, I may incorporate in the oil from 0.05 per cent to 0.5 per cent of my reaction products. In the case of lubricating oils for internal combustion engines, quantities of reaction product of the order oi 0.1 per cent to 0.7 per cent willinhibit the formation of color bodies and acidity, and will inhibit corrosion of hairing metals such as cadmium-silver and copperlead alloys. My reaction products, when employed in quantities of the order of 0.4 per cent to 0.7 per cent, will inhibit the formation of sludge, resinous bodies, or "lacquers, and will impart to the oils moderatedegree of film strength or extreme pressure characteristics.

Where a considerable degree or improvement in film strength or extreme pressure characteristics is required, my products may be employed in amounts of the order of 1 per cent to 2 per cent, or more. In those cases where it is desirable, from an economic point of view, to employ only sufllcient quantities of my reaction products to degree of film strength by the addition of other agents, I may add to the oil, for example, 0.4

per cent of my reaction products and 0.6 per cent 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 phosphite and 1.3 mol oi! cetyl alcohol 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 cetyl alcohol was initiated. The temperature of the reaction mixture was then progressively raised to about 340 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 per cent 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. 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 cetyl alcohol group.

The inhibiting effect of the above described reaction product upon the formation of sludge due to oxidation of lubricating oil is illustrated by the data presented in the following table. The

remove adhering oiL'and dried to constant weight. The amount of sludge is reported as milligrams per 10 grams of oil. The oil emplayed was a solvent refined S. A. E. 20 motor oil having a Saybolt Universal viscosity 01 313 seconds at F. and an A. P. I. gravity of 293.

Oil composition Mgs. sludge Blunkoil.. 197 Blank oil+0.i% by vol. of reaction product 99 Blank oil+0.3% by vol. of reaction product. 78 Blank oil+0.7/,, by vol. of reaction product. 59 Blank oil+l.5% by vol. of reaction product. 42

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 submerging in the oil samples to be tested a weighed cadmium-silver bearing, and heating the samples at a temperature of 340 F. for 24 The cresol distilled from the 4' assaass v hours while bubbling air through the samples test oils being withdrawn and examined at 8 at the rate or 3 liters per hour. At the comhour intervals. The results of the Chevrolet pletion of the heating period the bearings were engine tests are presented in the following table.

on 0.7 reaction rod. (used) on Oil (used) hours hours 9 Properties (now) a 10 a a2 s 16 24 a2 A.P.I vi new" use 25.2 26.1 s. U. vi: A003 an an 41s 4411 an ass 437 471 500 s U as as 61 as so s4 .02 2.0 as 4.9 as 1.6 2.8 4.1 4.1 .01 .42 '.83 .95 1.08 .as .59 .33 .91 .00 -11 .22 .42 .85 .18 .06 .18 .16 .oo .10 .07 .23 .18 .03 09 .05 .19 e, 002 2,677

removed from the oil samples, washed, dried and weighed. The loss 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 313 seconds at 100 F., and an A. P. I. gravity of The eiiectiveness 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 oi my reaction product were tested in an Almen extreme pressure lubrlcant'testing machine operated at 200 R. P. M. The pressures are expressed as lbs. per sq. in. projected bearing area sustained before seizure of the test bearing. The lubri-' eating oil employed was the same as used in the preceding test icr'corrosion inhibition.

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.

Oil composition Film strength LbL/eq. in. Blank oil 4,000 Blank oil+0.3 by vol. oi raaction product 12,000 Blank oil+1.li o by vol. of reaction product 17,000

To iurther demonstrate the eflectiveness of my novel reaction product, under actual conditions or use, tests were made employing a Chevrolet engine. The Chevrolet engine was run for 32hours at'3,000 R. P. M.. at a cranlrcase oil temperature oi 280 F., samples of the 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 thickened oils or greases, cutting oils, petrolatums, waxes, animal and vegetable oils, or mixtures thereof with hydrocarbon oils.

What 'I claim is:

1; The method of, producing an addition agent for hydrocarbon oils, which comprises reacting an ester of phosphorous acid with a relatively high boiling aliphatic 111001101 at such temperature and for such period of time as to introduce into said ester at least one high boiling aliphatic alcohol group.

2. The method of producing an addition agent for hydrocarbon oils, which comprises reacting an aryl ester of phosphorous acid with a'relatively high boiling aliphatic alcohol at such temperature and for such period of time as to introduce into said ester at least one high boiling aliphatic alcohol group.

3. The method of producing-an addition agent for hydrocarbon oils, which comprises heating an aryl ester of phosphorous acid with a relatively high boiling aliphatic alcohol at a temperature within the range of from 200 F. to

- phorous acid with from 1 to 2.5 mols of a relatively high boiling aliphatic alcohol at a temperature within the range or from 200' F. to 500 F.. or a period of time suflicient to introduce into said ester at least one high boiling aliphatic alcohol group.

FELIX C. GZEMSKI.