US2202364A - Lubricating oil - Google Patents

Description

Patented May 28, 1940 PATENT .oF Ics LUBRICATIN G 01L Peter J. Wielevich, now by judicial change of name to Peter J. Gaylor, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. ApplicationApril 3, 1937, 1 Serial No. 134.838

4 01...... (Cl. si-a) sired. For the purposes of the present inven- This invention relates to lubricating oils for use in internal combustion engines, and is more I particularly concerned withimproved addition agents therefor.

5 It is known that, small quantities, that is, between 0.1 and 2%, of metallic soaps suchas aluminum stearate, improve the properties of lubricating oils particularly with respect to lowering the pour point, decreasing the tendency to 10 cause sludge deposits in the engine, and increasing There is a serious objection to the use of these soaps, namely, that they do not remain dispersed in the oil but tend to settle out or cause gel formation on standing. This ob-- l5 jection canbe overcome to some extent by adding to the oil certain -solubilizing agen which have the effect of retaining the metallic soaps in more or less complete dispersion in the oil.

It has now been found that 'metallic soaps, if

II prepared from certain acids, will remain completely dispersed in lubricating oils, such as waxfree lubricating fractions of petroleum, without the necessity 'of using a'solubilizing agent and without sacrificing in any way the valuable 'prop-.

38 erties imparted to the oil by the ordinary soaps such as aluminum stearate- The presentinvention is directed to these improved soaps and tion. so I 7 According to the present invention the metallic soaps are prepared from crude acids derived from. the oxidation of wax, petrolatum or other wan hydrocarbons. These crude acids may be obtained in the following manner: Par- 35 aflln wax is oxidized with air or other gas containing free oxygen at a substantially low temperature of between 200 and 350 F; for a period of 2 to 4 hours,'pre ferably in an aluminum tower. Various catalytic materials such as potassium permanganate, manganese stearate or soda ash may be usedas catalysts to promote the oxidation. The reaction\ product is then saponified "with caustic soda preferably containing some The liberated acids are washed'and dlstilled and the product no obtained-is the-crude acid de-- method disclosed above.

willbe fully understood from the following description, the C10 to C20 fraction is preferred. The distillation is continued to about 480 F. under a 29 inch vacuum.- and the acids so obtained have an acid number of about 190 and a saponiflcation 'number of. about 240. Either the crude acids, or their fractions may be employed.

It has been found that it is desirable to employ acids substantially free of high molecular weight acids, say those above CzoOl' C24, sincethe soaps of the latter do tend to settle out from oil.

From these crude acids metallic soaps are pre- 3 pared. Aluminum is the preferred metal. Chromium, tin and manganese may also be used i but they are not as effective as aluminum. Since the acids obtained by the oxidation of wax are generally considered to be similar chemically to fatty acids, it would be expected that the aluminum soaps would behave in the same manner as aluminum stearate- But this is not the. case, especially with the crude acids obtained by'the Since it does not take very much soap to cause a. gel-like formation in oil, it is' essential for the purpose of this invention to remove any traces of gel-forming compounds by dissolving the aluminum soaps of the crude acid or its fractions in naphtha or similar suitable solvent, and filtering out the small amount of insoluble soap which is present and. which otherwise would cause gelformationin a-lubricating oil. 1 I

when the metallic soaps of the crude acids are added to lubricating oils in amounts from 0.5

to about 5%, there results an improved lubricating oil of increased oiliness, and decreased sliid ng tendency. The latter property is especially observed when such blends are employed for the lubrication of Diesel engines. Apparent- 1 ly, thecombustion characteristics of Diesel engines areconsiderably different from those encountered in the usual spar}: ignition automobile engines so that ordinary lubricants deteriorate much more rapidly and form a peculiar type of coating on the pistons. -'1 he-soap prepar ed according to the invention remains completely dispersed in the oil and shows no tendencyto separate cut or gel on standing.

There is an'indlcation that the presence of lactones or lactone-like materials are desirablein maintaining a non -stringy consistency in mineral oils. Hence, it is desirable, during saponiflcation of the wax acids, to avoid excess alkali and thereby to prevent hydrolysis of such lactones or-lactides. The best procedurex is to make the 2 acids neutral to litmus f with alkali, and then some free wax acids are added to make certain that free alkalinity does not exist. It is also possible to add additional lactones or lactides to the wax acids prior to saponiflcation or conversion to aluminum or other soap.

It will be understood that other agents may also be added to these oils, not for the purpose of solubilizing thesoap, for this is not necessary;

pounds such as phenol sulfldes or polysulfldes is tion of the invention:

' moval but rather to improve the oil with respect to other properties. Thus other oiliness agents, pour inhibitors, V. I. improvers, extreme pressure agents, voltolized products, corrosion inhibitors, and

sludge preventors may also be added as well as other agents such as oxidation inhibitors, thickeners, dyes, etc. The addition of corrosion inhibltors such as soluble peroxides or sulfur comespecially useful. The effective compounds in the latter category are phenol sulfides having the formulav H OH where B. may be H, or an alkyl radical, R

alkyl, alkyl-aryl, or arylra'dical, and n is an integer from 1 to 4;

The use of these improved soaps is not re-.

,stricted to any particular type of lubricating oil but is applicable generally to all lubricating oil fractions whether obtained'by the distillation, cracking, hydrogenation or other treatment of petroleum, coals, tars. lignites or fractions thereof. However, as' pointed out above, the. greatest .value for-such compositions is in the Diesel lubrication field.

It will be understood that wherever the term crude acids" is ,used'in the specification or ap-v pended claims, it means the product of oxidation of paraflin wax or other waxy hydrocarbons after removal of ,unoxidized wax but before the renon-saponiflable material may be removed, but it is desirable to allows portion or all of it to remain inthe crude acid mixture.

The following examples illustrate the applica- 200 gramsof crude acid derivedfrom the products of oxidation-of wax and having the following characteristics are reacted with grams of NaOH, an amount greater than that calculated to be necessary from the acid number. Sinceit is preferable vto avoid excess alkali, some additional wax acid is added until the mixture is neutral to litmus. The soap solution is placed in a separatory funnel and is .slowly added to a relatively large vquantity of hot water. The mass is agitated vigorously and simultaneously a concentrated solution or aluminum sulfate (1.00 grams of,Al:(S04) a) is added. The insoluble aluminum soap thereby formed is separated, and is' washed first with aluminum sulfate solution .and then with water, followed by dissolving it in Varsol (heavy naphtha) and of any other constituents. Some of thehlterlng. The-soap contains 4.32% Al by-analysis. It is dissolved in lubricating oil by heating for 3 hours at a temperature between 200 and 400 F. a V

1% of this aluminum soap is added to a lubricating oil. The following table shows the comparativeinspections of the oil with and without the soap:

y when the 011 without any soap was run in a C. F. R. engine it had .a demerit rating of 1.43. On the other hand. when the oil containing 1 of the Al soap was run in the same engine, it

a demerit rating of only 0.93. I

Example II In another experiment 1% of an Al soap of the crude acid containing only 2.92% Al was added to the same oil as used in Example 1. time following table shows the comparative inspections:

when the oil without any soap was run in a C. F. R. engine it had. ademerit rating of 1.43. The oil containing 1% of the Al soap had a demerit rating of only 1.30 under the same conditions.

The term"demerit rating" as used in the above examples is a value arrived at after inspection of the used oil and all of the engine parts in contact therewith. The value is such that the smaller the number, the better the performance.

In the runs using the oil containing 1% of the aluminum soap, no ring sticking occurred and "the "varnish formation was considerably less than with the unblende'd oils, especially in th'.

7 case of, the soap containing the greater amount of aluminum. The carbon formation was also the unblended.

This invention is notdimited by any theories of the mechanism of the action of metallic soaps onlubricating oils nor by any details which have been given merely ,forpurposes of illustration, but is limited only in and by the following claims Oil Al soap 0! crude acid Gravity m. P. 1-, 21.8 22.3 Flash 410 425 Fire, I 470 475 Saybolt via. l00- 726 771 Baybolt vls. @210" F 62. 2 65 Pour point, 5 0 Olou g int, F.. None 0010: b n 12% 42: 8t'b nradso I 0. 0 20 a: n o n Neutralization number .04 l. 94 Ssponlflcation number 2. 00

considerably less with the blended oils than with in which it is intended to claim all novelty inherent in the invention.

I claim: 1. An improved motor oil comprising stantially wax-free viscous mineral oil and 'a .l

small percentage of a soluble'no'n-gellin'g aluminum soap of'acids derived from the product of hydrocarbons, acids mild oxidation of waxy p v 2,202,884 I i 3 having not over 24 carbon atoms, and possessing soap having the property of increasing the oxidathe property of increasing the oxidation rate of the mineral oil.

2. Composition according to claim 1'in which of Al soaps of crude acids obtained by low. temthe aluminum' soap is present in amounts between 0.5 and 5%.

3-. An improved motor oil' comprising a viscous wax-free mineral oil and a small percentage of an aluminum soap of crude acids inthe Cm to C20 molecular weight range derived from the 0 product of mild oxidation of paraifin wax said tion rate or the, mineral oil.

4. A substantially wax-tree lubricating oil for Diesel engine lubrication containing 0.5 to 3% perature oxidation of petroleum wax, substantially free of. acids of over 24 carbon atoms and possessing the property of increasing the oxidation rate of the mineral oil.

PETER J. wmzEvren.