US2253399A - Lubricating oil composition - Google Patents

Description

Pale-nies' @3.19.1941

- N Iulu'r'isn {STATES- Alali'liazii Lonarcsrmo 'r OFFICE `Olli` COMPOSITION John E. Schott. New York, N. Y., and leonard B. Churchill, Cranford. Nfl., :migliorato Tide y Water Anocia'tcd 0il Company. New York. N.Y.,aoorporationotDelawal-e No .Accusation april s, lass. serai Nazoaovz schim. icl; e-437) y Y t l hydmcarbon lubricating oil, aluminum stearato This invention reines to the. lubrication or internal combustion engines; and is particularly directed, although not restricted, to satisfactory and improved lubrication in' the Diesel type AoiL engine wherein extreme service wn'ditions of temperature and pressure are encountered.l To y and triethanolamine," "hydrocarbon lubricatingl oil compounded with aluminum stearate and triethanolaminef or the like are'intended to desigl nate and embrace any liquid hydrocarbon'lubri- Veating oil v composition in which aluminum steathe attainmentof these and other ends, the

" i invention provides and encompasses compounded liquid. petroleum compositions consisting essentially of motor-'lubricating oil with aluminum rate and triethanolamine have been incorporated regardless of what complex compoundor mixture may actually exist -in the compoimdedpnoduct.

' stearatefand triethanolamine as compounding ingredients. -The compounded products retain substantially theviscoslty and owcharacte'risi l .tics of an oill and thereby distinguish from other compounded `li'lliricants of the plastic ilow type such as greases and so-called liquid greases. i

design has made lubrication of Modern e internal co ustion engines an increasingly diiiicul't and speciilc problem. fIn high speed units and-especially in Diesel engines lubrication Yis 4required under service conditions'of such severity as to approach the limit o't safe and emcient operation with straight mineral oils. High temperaturesand pressures, the catalytic eifect of hot metallic surfaciescontinuously contacted' under these conditions, accumulating concentra- .tion of oxidizing agents and autocatalytic eiect developing asdeterioration progressesv all con` tribute to lubricant degradation. The lubricating capacity ofthe oil is rapidly diminished by chemical and thermal"deterioration, and the products of deterioration create seriousoperating problems.A Gummy for lacquer-like products,

`sluclges. asphaltenes and coke are formed and the accumulation of such material 'has a lnnturally'harmful effect jupon engine parts and operation. Ringsticking. ineirective cylinder lu iirication. increased wear, scoring of cylinder 'walls and like trouble results, andirequent-shut- 'down forV cleaning. overhauling and often replacing oi' engine partsmay be necessary.

According tothe present invention, the foregains dimculues are obviatea by lubricating internal combustion egines with a compounded lubricant comprising hydrocarbonlubricating oil,

aluminum stearate and'triethanolamine.

Thereisevidence that triethanolamine reacts with or n'iodiiiesaluminum stearate; and we believe that our compounded lubricating compo-4 sition containsa modified aluminum stearate or o an. aluminumr stearate-triethanolamine complex along with which mayl be some proportion of the `respective compounding ingredients as added. f-

t is to be, understood; therefore,` that such 'expressionslas "lubricating composition comprising 'The exact chemical mechanism oi' mineral oil deterioration in internal combustion engine service is-not clear although authorities have reasonably concluded that such .phenomena as polymerization. oxidation and thermal decomposition are predominant factors. however. to limit or attempt an explanation of 4results attending lubrication o! internal combustion engines with the compounded, olllof the inlvenizion on the basis. ot these or other theories.

Results marking' a distinction between success and failure in engine performance animi lubrication are suilicient evidence that the compoundl ing oi aluminum stearate and triethanolamine with hydrocarbon lubricating oil performs novel and highly useful function.4

lEngine tests are to be preferred for the comparative evaluation of motor oils, especially when intended foiservice in the lubrication of -Diesel Y engines, although the well known Indiana oxida- "tion test or a modiiicationthereof in which the test is carried out in the presence of aweighed quantity' of steel wool may serve to provide an index. Sludge values do not seem tohave particular significance but the character of the oxidation products at -the end of a 7i) hour run at 341 F. is .an indication of-conditionsthat may be expected in engine service. Good Diesel engine lubricants-generally give a clean tube with'- .out resinous or products adhering to the walls. `Ii.' the sludge is sticky, gummy and uniilterable, the probabilityds that the oil will cause,

ring sticking in engine service. Inthemodied.. -Indianai test there is usually ay slight decrease in weight ot the steel wool' with promising oils' and the steel wool when washed clean-with hot 'y `kerosene followed by naphtha has a bright appearancee In the case ofunsuitable oils the steel It is not intended.

with the Indiana oxidation test and with the modified form of this in which the test is carriedl out in the presence of a weighed quantity of steel wool.- In all test operations, comparison was with blank-'runs in which straight mineral oil as used in the compounding of a given lubricant according to the invention supplied the lubrication.

The compounding of aluminum stearate and triethanolam'ine with a hydrocarbon motor oil intended for service in the lubrication of inter-i nal combustion engines gave consistently im-y hour, agitation boing continued throughout the treatment. Aluminum stearate is but sparingly soluble in mineral oil of lubricating oil viscosity,

and when added at room temperatures tends to agglomerate-hence the desirability of thoroghly stirring the soap-oil mixture prior to addition of triethanolamine. If the soap-oil mixture is heated prior to triethanolamine addition, visccs- 1 ity builds up and at about 190 F.220 F. there proved results in all tests. In both automotive and Diesel engine service ring stickingY and related diiliculties were substantially to entirely eliminated, with the lubricant continuing to perform its lubricating function satisfactorily over extended test periods under rigorous operating conditions. Good general engine condition was observed upon inspection at the termination of y the tests. In comparative test runs, straight mineral oils were markedly inferior, especially in Diesel engine service where relatively short runs resulted in badly stuck rings, inadequate lubrication and poor general engine condition at shutdown.

The invention has general utility in the art of motor oil preparation and use. The base stock which is compounded as disclosed herein may comprise anyl'hydrocarbon lubricating oil and is not restricted to particular crude petroleum g sources or to particular degrees of refining. For

example, aluminum stearate and triethanolamine have been compounded with motor oil from Pennsylvania crude and with motor oil froman asphaltic-naphthenic 'California crude. In each case like beneit in the way of improved lubrication and 'elimination of ring sticking or like engine trouble ensued. This is a particularly advantageous feature of the invention. Many compounds proposed for addition to petroleum oils are, as is well known, eective or compatible only with certain specific oils of prescribed crude origin.

In general it is preferred that the base stock used in preparing lubricating. compositions as herein be a motor oil which has had a good or superior degree of rening in the course ofproduction.- In the case of naphthenic or asphaltic base stocks a reilning treatment with sulfuric acid or a combination of solvent extraction and acid treatment is recommended. With Pennsylvania and like paraillnic base stocks less rigorous renningtreatment is necessary. One reason for the stated preference is the conventional desirability of good or quality lubricating oil simply from the viewpoint of .superior capacity as a? lubricant. In a more pertinent aspect, however, we believe thatour compounded lubricating composition has greater general utility in internal combustion engine service and'gives better overall performance when vwell renned base stockl is used.

In one embodiment'. the lubricating composi-v tions of the invention niay be prepared by introducing suitable proportions of aluminum stearate (for example. 1% by weight based on theV oil) into a selected motor oil at ordinary temperature, agitating thoroughlyfor sumclent time to 4is a marked gelling eiect which oiers considerable resistance to agitation at this tempera- -ture stage. As heating is continued, the gel thins out somewhat and themixture may be stirred without excessive power consumption. If desired, this procedure may of course be used and triethanolamine added after the mixture has been raised to elevated temperature.

It is far more desirable, however, to introduce the triethanolamine to an agitated soap-oil mixture before applying heat to the latter since in this procedure no abnormal viscosity increase or gelformation occurs during the heat treatment and a fully fluid mixture is maintained through out. Apparently some reaction between the compounding agents or ingredients is initiated immediately upon admixture, and this progresses as heat is applied.

As.indicated above, the mixture of oil and both compounding ingredients is heated at elevated temperaturepreferably 270 F.300 F. for about one-half hour which is usually sufilcient to complete reaction of the triethanolamlne. If the heat treatment has been .insuilicient for necessary completeness ofreaction,fthe oil upon coolr ing to room temperature will be turbid and some further heating is required. Ordinarily, however,

' atures a longer period of heat treatment naturally is required. v

Aluminum stearato of high purity is preferred. Commercial aluminum stearates usually contain from 0.5% to 3% of sulfate as sodium sulfate which is not especially objectionable, although with some oils the higher proportions of sulfate in the aluminum stearate may occasion a small degree of dimcultly removable ysedimentation' upon prolonged storage of the compounded lubricating composition. Ihis does not, however,

- seem to have any particularly deleterious eil'ect obtain a well disseminated mixtureof soap infA oil, adding suitable proportions of trlethanolaa' mine (for example, 0.1% by weight based on the oil) to the still agitated mixture, applyingA heat sumcient to raise the temperature 'to about t t 270 '1H-300 F., and maintaining theA mixture at in engine service although the oil naturally is inferioi in appearance to compoundedioils which are clear solutions'as are usually y,obtained in the preparation of lubricatingcompositions according to the invention. l

The mono, di, and' tri-stearates 'of aluminum are marketed l :ommercially and are separately available.' aIn each instaiieitisfprobable that the product contains some impurity of one or both of the otherv forms with possibly some free stearic acid as well. In most of our exploratory practice of` the invention we have used the product marketed commercially as such temperature for approximately one-half 15 aluminum distearate. but the mono-stearateand the tri-stearate likewise have'utility in the preparation of compounded lubricating oilsas herein. The ash content, of course,v diiers with the three forms and when motor oil specications include a maximum allowable ash, this must be given consideration in selecting the proportion of V a particular aluminum stearate to4 be used in the :preparation of the compounded oil. For examy ple, the mono-stearate naturally gives a higher percentage of ash than the di-stearate, and therefore a larger Weight proportion (based on the oil) of the latter can bevused whilestiil meeting a prescribed ash 'in the compounded oil.

vThe lubricating compositions ofthe invention have a higher viscosity and visocity index than the motor oil used as a base stock. If, the increase in viscosity is reasonably limited, this is a distinct advantage, but the necessity of avoiding too4 great a deviation from given specifications for different grades of motor oil makes it undesirable to have excessive viscosity increase in the compounded-product. We have found that advantages in the way of improved lubrication and engine operation are readily, and consistently obtained with Ilubricating compositions of the invention when the viscosity of the compounded product is increased only to a reasonable and desirable degree.

t Proportions of aluminum stearate and of triethanolamine to be used as compounding'ingredients for the purposes of the present invention compounded with about 1.0%-1.5% by weight of aluminum stearate and proportions by weight of triethanolamine equal to about 8-10% of the soap will provide lubricating compositions acwill varywith oils from diilerentcrude'sources `v and with differently 'refined oils from the same crude source. In any given instance a degree of latitude is available in respect of desiredfproportions, and the amounts of each ingredient are selected with regard both to relative and conjoint effect. Where percentage ash vis a xed specica- (as is sometimes speciedfor Diesel engine lubri- -cantsi this will determine the upper limit o'f 4 aluminum stearate that can be used. More generally, the viscosity of the compounded product may. be regarded as a limiting factor. Beyond about 2% or 3% ofjaluminumv stearate, the

viscosity is increased by the soap to some'degree independently of the triethanolamine.

`ing at high sustained Vspeeds and under extreme l tion for an oil to be used in'particular service l Relative to each other, the proportion of triethanolamine must be sumcient to avoid `more than moderate increase in viscosity due to the addition' of aluminum stearate but must be below a proportion effective to vimpart turbidity to the compounded'oil. As a general proposition, we,

havel found-,that with goodA quality commercial aluminum di-stearate'effective and suitable proportions of triethanolamine fall in the range of about 5% to about 20%, and preferably about 8% to about 15%, ofthe soap. 4In many experiments using a -well reiined Pennsylvania base motor oil of S. A. E. 20grade as a base stock we have found that triethanoiamine. as 10% of the soap (e. g.

` aluminum stearate 1% and hiethanolamine 0.1%,

both by weight basedon the weight of mowion used in the eompoimdins) gives very satisfactory cord'ng to the invention which are entirely satisfactory for the majority of contemplated services.

In any given instance, however, the desired prooil of suitable viscosity for the intended service which has' been compounded and heated with approximately 1% by weight of aluminum stearate and a quantity of triethanolamine, in the range of about 5% to about 20% by Weight of said aluminum stearate, sufiicient to improve the lubricating eiiiciency-of the oil, said compounded oil having substantially the viscosity and fluidity characteristics of the uncompounded oil.

2. Substantially liquid and non-stringy lubricating oil for internal combustion engines operatservice conditions of temperature and pressure` lsuch as may be encountered in Diesel engine 111 brication, which comprises a hydrocarbon lubricating oil of suitable nominal viscosity for an intended service compounded and heated with small amounts of aluminum stearate and of triethan- 01am-ine in proportions such that the normal viscosity of the oil is not increased beyond' a,

reasonable and desirable degree for its intendedv tion engines, which comprises compounding hydrocarbon lubricating oil of suitable viscosity for the intended service with approximately 1% by weight of aluminum stearate anda quantity of triethanolamine, in the range of about 5% to about 20% by weight of said aluminum stearate, sumcient to improve the lubricating emciency of the oil, and then subjecting the resulting mixture to a period of heat treatment at a temperature not substantially lower than 270 F.

-' JOHN n. scHQ'I'r. LEONARD a. cnuncmu..