US2260341A - Lubricating oil composition - Google Patents

Description

Patented Oct. 28, 1941 2,260,341 v LUBRICATING on. COMPOSITION John E Schott, New York, N. Y., ass ignor to [lide Water Associated Oil Company, Bayonne, N. J a corporation of Delaware No Drawing. Application April 5, 1938,

Serial No. 200,073

3 Claims.

This invention relates to the lubrication of internal combustion engines; and is particularly directed, although not restricted, to satisfactory and improved lubrication in the Diesel type of engine wherein extreme service conditions of temperature and pressure are encountered. To the attainment of these and other ends, the invention provides and encompasses compounded liquid petroleum compositions consisting essentially of motor lubricating oil with aluminum stearate and butyl carbitol (hydroxy butyloxyethyl ether) as compounding ingredients. The compounded products retain substantially the viscosity and fiow characteristics of an oil, and thereby distinguish from other compounded lubricants of the plastic flow type such as greases and so-called liquid greases.

Modern engine design has made lubrication of internal combustion engines an increasingly difficult and specific problem. In high speed units and especially in Diesel engines lubrication is re- .quired under service conditions of such severity as to approach'the limit of safe and efficient operation with straight mineral oils. High temperatures and pressures, the catalytic effect of hot metallic surfaces continuously contacted under these conditions, accumulating concentration of oxidizing agents, and auto-catalytic effect developing as deterioration progresses all contribute to lubricant. degradation. The lubricating capacity of the oil is, rapidly diminished by chemical and thermal deterioration, and the products of deterioration create serious operating problems. Gummy or lacquer-like products, sludges, asphaltenes and coke are formed and the accumulation of such material has a naturally harmful effect upon engine parts and operation. Ring sticking, ineffective cylinder lubrication, increased wear, scoring ofcylinder walls and like. trouble results, and frequent shutdown for cleaning, overhauling, and-often replacing of engine parts may be necessary. I

Accordingto the present invention, the fore- ,going difliculties -are obviated by lubricating inas lubricating composition comprising hydro carbon lubricating. oil, aluminum stearate and butyl carbitol, hydrocarbon lubricating oil compounded with aluminumstearate and'butyl carnbito or the like are intended to designate and embrace any liquid hydrocarbon lubricating oil composition in which aluminum stearate and butyl carbitol have been incorporated regardless of what complex compound or mixture may actually exist in the compounded product.

The exact chemical mechanism of 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. It is not intended, however, to limit or attempt an explanation of results attending lubrication of internal combustion engines with the compounded oil of the invention on the basis of these or other theories. Results marking a distinction between success and failure in engine performance and lubrication are sufiicient evidence that the compounding of aluminum stearate and butyl carbitol with a quantity of steel wool may serve to provide anindex. Sludge values do not seem to have particular significance but the character of the oxidation products at the end of a; 70 hour run at 341 F. is an indication of conditions that may be expected in engine service. Good Diesel "engine lubricants generally give a clean tube without resinous or gummy products adhering to the walls. If the sludge is sticky, gummy and unfilterable, the probability is that the oil willof compounded lubricants according to the pres ent invention, actual lubrication of engines both of the spark ignition and .of the compression ignition type was relied upon 'as the significant criterion. Collateral indications were obtained with the Indiana oxidation test and with the modified form of this in which the test is carried 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 usedin the compounding of a given lubribrication.

The compounding of aluminum stearate and butyl carbitol with a hydrocarbon motor oil intended for service, in the lubrication of internal combustion engines gave consistently improved results in all tests. In both automotive and Diesel engine service ring sticking and related difllculties 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 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 part of motor oil preparation and use. The base stock which is compounded as disclosed herein may comprise any hydrocarbon lubricating oil and is not restricted to particular crude petroleum sources or to particular degrees of refining. For example, aluminum stearate and butyl carbitol have been compounded with motor oil from Pennsylvania crude and with motor oil from an asphaltic-naphthenic California crude. In each case like benefit in the way of improved lubrication and elimination of ring sticking or like engine trouble ensued. This is a particularly butyl carbitol. If the soap-oil mixture is heated prior to butyl carbitol addition, viscosity builds up and at about 190 Ill-220 '25. there is a marked gelling efiect which offers considerable resistance to agitation at this temperature stage. As heating is continued, the gel thins out somewhat and the mixture may be stirred without excessive power consumption. If desired, this pro; cedure may of course be used and butyl carbitol added after the mixture has been raised to elevated temperature.

It is' far more desirable, however, to introduce the butyl carbitol to an agitated soap-oil mixture before applying heat to the latter since in this procedure no abnormal viscosity increase or gel formation occurs during the heat treatment and a fully fiuid mixture is maintained throughout. 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 temperature preferably 300 LEE-340 F. for

about two hours which is usually sumcient. If.

the heat treatment has been insuflicient for necessary cc mpleteness of reaction, the oil upon cooling to room temperature will be turbid and advantageous feature of the invention. "Many compounds proposed for addition to petroleum oils are, as is well known, efiective or compatible only with certain specific oils of prescribed crude c gln.

In general it is preferred that the base stock used in preparing lubricating compositions as herein be a motor ofl which has had a good or superior degree of refining in the course of production. In thecase of .naphthenic or as'phaltic base stocks a refining treatment with sulfuric acid or a combination of solvent extraction and acid treatment is recommended. With Pennsylvania and like parafllnic' base stocks less rigorbus refining treatment is necessary. One reason for the stated preference is the conventionaldesirability of good or quality lubricating oil simply from the viewpoint of superior capacity as a lubricant. In a more pertinent aspect. however, I believe-that my compounded lubricating composition has greater general utility in internal' combustion engine service and gives better overall performance when well refinedbase stock tation being continued throughout the treatment.

Aluminum stearate'is but sparingly soluble in mineral oil of lubricating oil viscosity, and when added at room temperatures tends tofazglomeratehence the. desirability of thoroughly stirthe soap-oil mixture prior to addition of some further heating is required. Ordinarily, however, the indicated temperature and time of heating suffices to prepare a clear oil solution comprising the improved motor oil'of the invention. Additional heating not unduly prolonged does no harm.

With most oils a temperature above about 340 F. might be used if care is exercised but this is not regarded as particularly desirable since the objectives of the invention are satisfactorily attained with greater certainty and economy when the temperature does not exceed 340 F. Temperatures somewhat below 300 F, may be used successfully but with lower temperatures a longer period of heat treatment naturally is required.

Aluminum stearate of high purity is preferred. a

degree of difiicultly removable sedimentation upon prolonged storage of the compounded lubricating composition. This does not, however, seem to have any particularly deleterious effect in engine service although the oil naturally is inferior in appearance to compounded oils which are clear solutions as are usually obtained in the preparationof lubricating compositions according to the invention.

' The mono-, di-, and tri-stearates of aluminum are marketed commercially and are separately available. In each instance it is probable that the product contains some impurity. percentage ticular aluminum stearate to be used in the prep aration of the compounded oil. For example. the

In most of our E have a higher viscosity and viscosity index than of aluminum stearate and proportions by weight the motor oil used as a base stock. If the in- V crease in viscosity is reasonably limited, this is a distinct advantage, but the necessity of avoiding too great a deviation from given specifications for diiferentgrades of'motor oil makes it undesirable to have excessive viscosity increase in the compounded product. I have found that advantages in the way of improved lubrication and engine operation are readily and consistently obtained with lubricating compositions. of the invention' when the viscosity of the compounded product is increased only to a reasonable and desirable degree. e

Proportions of aluminum stearate and of butyl carbitol to be used as compounding ingredients for the purposes of the present invention will vary with oils from different crude sources and with differently refined oils from the same crude source. In any given instance a degree of latitude is available'in respect of desired proportions: and the amounts of each ingredient are selected with regard both to relative and conjoint effect. Where percentage of ash is a fixed specification for an oil to be used in particular service (as is sometimes specified for Diesel engine lubricants) this will determine the upper limit, of 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% of aluminum stearate, the viscosity is increased by the soap to some degree independently of the butyl carbitol.

a Relative to each other, the proportion of butyl carbitol must be sufficient to avoid more than moderate increase in viscosity due to the addition of aluminum stearate. Butyl carbitol is soluble per se in hydrocarbon lubricating oil to a degree well in excess of the requirements of the present invention and may therefore be used in compounding proportion greater than that necessary for-conjoint action with aluminum stearate as herein. Some degree of benefit results from the presence of butyl. carbitol in mineral oils, and

an economical excess of this constituent consequently may be desirable.

As a general proposition, I have found that with good quality commercial aluminum distearate effective and suitable proportions of butyl carbitol fall in the range of about 5% to about 20%, and preferablyabout 8% to about 15%, of the soap. Inmany experiments using a well refined Pennsylvania'base motor oil of S. A. E. 20 grade as a base stock I have found that butyl carbitol as 10% of the soap e. g. aluminum stearate 1% and-butyl carbitol 0.1%,

of butyl carbitol equal to about 8-10% of the soap will provide-lubricating compositions according to the invention, which are. entirely satisfactory for the majority of contemplated services. In anygiven instance, however, the

desired proportions of materials may be readily determined by simple experiment, and specific illustrative disclosures herein'are not intended in v a limitative sense. 1

In my copending application Serial No. 404,720, filed July 30, 1941, as a continuation-in-part of the instant application, I have disclosed and claimed certain generic aspects of the present invention, to wit, a lubricating composition compounded with an aluminum soap of a saturated fatty acid and a glycol or diglycol mono-ether of which the here claimed composition compounded with aluminum stearate and hydroxy butyloxy-ethyl ether is one species.

I claim:

1. Substantially liquid and non-stringy lubricating oil for internal combustion engines operating at high sustained speeds and under extreme service conditions of temperature 'and pressure such as may be encountered'in Diesel engine-lubrication, which comprises a hydrocarbon motor oil of suitable viscosity for the intended service compounded with approximately. 1% by weight of aluminum stearate and a quantity of hydroxy butyloxy-ethyl ether, in the range of about 5% to 20% by weight of said aluminum stearate, sufficient to improve the lubricating efiiciency of the oil, the ingredients of said compounded oil being subjected to a-heat-' engine lubrication, which comprises a hydrocarbon lubricating oil of suitable nominal viscosity for an intended service compounded and heated with small amounts of aluminum stearate and hydroxy butyloxy-ethyl ether in proportions ,such that thenormal viscosity of the oil is not increased beyond a reasonable and desirable degree for its intended service,' the aluminum stearate being introduced in an amount not less than one percent. 3. Method of preparing motor oil composition suitable for the lubricating of internal combustion engines, which comprises compounding hydrocarbon lubricating oil ofsuitable viscosity for the intended service with approximately 1% both by weight based on the weight of motor oil used in thecompounding) gives very satisfactory results in every regard. Optimum proportions of butyl carbitol relative to aluminum stearate will vary when different motor oils comprise the base stock; and likewise will vary to some extent depending upon the amount of soap. With larger proportions of soap the butyl proportion generally should be larger. I believe the motor oils compounded with about 1.0%-1.5% by weight by Weight of aluminum stearate and a quantity of hydroxy butyloxy-ethyl ether, in the range of about 5% to about 20% by weight of said aluminum stearate, sufficient to improve the lubricating efiiciencyof the oil, and then subjecting the resulting mixture to a heat treatment at a temperature not, substantially lower than 300 F. for a period of time sufiicient to produce a resulting product which has substantially the viacosity and fluidity characteristics of the uncompounded oil. n JOHN E. SCHO'I'I.