US2081075A - Lubricating oil composition - Google Patents

Description

Patented May 18, 1937 UNITED STATES LUBRICATING on. oomosrr oN Arnold G. Vobach; Whiting, Ind., assignor to" Sinclair Refining Company, New York, N. Y.

a. corporation 01' Maine No Drawing. Application July 6, 1936, Serial No. 89,120

My invention relates to improvements in compounded petroleum lubricating oils. The improved lubricating oil compositions of my invention'consist essentially of a petroleum lubricat- 5 ing oil and calcium phenyl stearate, or calcium phenyl stearate together with calcium stearate, or calcium phenyl stearate or a mixture of calcium phenyl stearate and calcium stearate together with phenyl stearic acid, in amount, or amounts, insuificient materially to alter the normally liquid character of the petroleum lubricating oil itself, 05-25% on the oil for example.

Calcium phenyl, stearate, and its production, have been described in the chemical literature, see for example Journal of the American Chemical Society, 49, 1103-1106, (1927), and 52, 1172- 1174, (1930). Calcium stearate has long been used in compounded petroleum lubricating greases. This invention relates to improvements upon the oils used for their lubrication, particularly, with respect to operating temperatures 30 and pressures. At present, the Diesel type of engine probably represents extreme requirements in both of these respects, but it is not alone in the imposition of severe burdens upon the lubrieating oil used. The useful operating life of,a lubricating oil, in such service, is determined, in large measure, by its thermal stability and by its physical capacity to continue functioning as a lubricant, at the high temperatures and high pressures encountered. One measure of thermal stability is resistance to oxidatiomand the consequent tendency to form sludge, but in another aspect the efiect of thermal instability is determined not only by the extent of oxidation or de- -composition but also by the character of the products of such decomposition or oxidation and by the extent and location, within the engine, of deposits of such products.

The improved lubricating oil compositions of my invention have, in addition to the lubricating 50 properties of thepetroleum oils of which they are compounded, a high solvent capacity for sludge, of the character formed by oxidation of petroleum lubricating oils and, perhaps of even greater incident of the normal operation of the engine.

In this aspect, the lubricating oil compositions of my invention render the engines in which they 10 are used self-cleaning to an important extent.

In the Diesel typeof engine, for example, the

-.high temperatures to which the lubricating oil is subjected, particularly at the top of the stroke, frequently causes deposition of sludge and car- 5 bonization in the groove forand behind one or.

more of the piston rings. Using parafilnic type lubricating oils such difflculties are usually more pronounced with respect to the uppermost ring; using naphthenic type lubricating oilthey are usually more pronounced with respect to the lower rings. consequent sticking oi the rings rapidly deprives the piston and cylinder wall of proper lubrication inducing excessive wear and, frequently, scoring of the cylinder wall. The formationof such carbon deposits, hard enough and coherent enough to involve sticking of the rings, is materially retarded, if not avoided, by the use of the improved lubricating oil compositions of my invention, and in this aspect the self-cleaning properties of the lubricating oil compositions of my invention, with respect to the engine, make a mere change of oil a substitute, economical with respect both to loss of service time and cost, for

many otherwise necessary cleaning and repair jobs.

I minimum 96% free fatty acid as oleic acid and having a maximum cloud test of 45 F., is added to this mixture with'stirring, the addition being made over a period of about an hour. 1 This retained at a temperature 'of -180 F. for 6 or' '7 hours. For at least the last half hour of this period the reaction mixture is held at'180 F. to insure completion of the reaction and to assist in stripping hydrochloric acid from the reaction mixture. The reaction product, a pasty liquid,

- is'then added to about $4 of its volume of aqueous hydrochloric acid,- 20% HCl, at ordinary temperature. The ensuing reaction brings the temperature, for example, to about 170 F. This reaction mixture is thoroughly stirred and the aqueous acid solution is then separated from the oily product of the reaction, by decantation for example. This separated oily product is thoroughly washed with water, advantageously with hot water, in two successive stages with about 01' its volume of hot water in each stage for example. This washing should in any event be continued until a quantitative test for aluminum in the wash water is negative. After this washing, the reaction product is a thin, oily, dark green liquid. It is allowed to stand to settle out 640650 F.for any period long enough to'involve decomposition. When effecting the distillation under a vacuum of 4 millimeters of mercury absolute pressure, a first cut of about 25% is taken on up to the point at which the temperature of the liquid in the still reaches 466 F. and a second cut of about 53% is taken off as the temperature of the liquid in the still rises from 466 F. to 590 F. The second of these two distillate fractions can be saponified with lime to produce the material to which I refer as calcium phenyl stearate, or these two distillate fractions can be combined and together saponified with lime to produce a mixture of this calcium phenyl stearate and calcium stearate. For example, 4 parts of the second fraction, or 4 parts of the first and second fractions together, diluted with an equal weight of petroleum naphtha boiling between about 200 F. and 322 F., can be saponifled with about 1 part of hydrated lime, added in 2 or 3 portions with thorough stirring. The temperature of the reaction mixture rises to about 160 F., for example, and then by external heating with reflux-condensation of the naphtha diluent is maintained at about 190 F. until the saponification is complete. This reaction mixture is further diluted with about twice its volume of the same petroleum naphtha and unreacted lime is separated by centrifuging. Benzol may be used perature of the liquid in the still to about 375 F., I

carrying out the distillation under a vacuum if necessary to keep within this temperature limitation. This undistilled liquid product is used as calcium phenyl stearate,'or asa mixture of calcium phenyl stearate and calcium stearate if tion or fractions to 1 part of hydrated lime for example without dilution until the saponification is completed and the reaction mixture then diluted prior to separation of um'eacted lime, the saponificatiorr being otherwise carried out as just described. Or, it is also possible to use that amount of hydrated lime just necessary to complate the saponification, and to effect the saponification without dilution either during the sa'- poniflcation or following the saponification.

In referring to phenyl stearic acid herein, I refer to the calcium compound constituting the major component of the saponification of the second distillate fraction from the condensation of oleic acid with benzol as described in the preceding paragraph although, of course, I intend to refer by this term to this same material by whatever process it may be made. I believe this calcium phenyl stearate to be the calcium salt of 9,10 phenyl stearic acid, but I do not predicate my invention upon this identification of the compound as a matter of terminology. The refractive indices, acid numbers, saponification numbers and iodine numbers of the total reaction product of the oleic acid-benzol'condensation, of the first and second distillate fractions and of the residual fraction produced as described in the preceding paragraph, as determined in one instance, were as follows:

Total reac- First Second Resition cut cut due product Refractive index at 20 C 1. 4875 l. 4610 l. 4880 l. 5171 Acid number 166 193 127. 5 Saponiflcation number 168. 1 192. 6 161. 7 Iodine number; 10 1. 96 4. 08 23. 6

In compounding the improved lubricating oil compositions of my invention with the usual petroleum lubricating oils, the calcium phenyl stearate, .or the mixture including calcium phenyl stearate and calcium stearate, are added to the lubricating oilin proportions ranging from about 0.5% up to about 2.0% or 2.5% by weight on the of 500 seconds at. 100 F., Saybolt universal and.

boiling 10% up to 700 F. and 90% up to 900 F.,

approximately, and 1%% by weight on the oil of a mixture of calcium phenyl stearate and calcium stearate produced by saponifying together the first and second distillate fractions from the vacuum distillation of the reaction mixture from the condensation of oleic acid with benzol as described in the second preceding paragraph to be particularly advantageous. The Indiana Oxidation Test with this composition was 24-25 hours as compared to 14 hours for the petroleum lubricating oil alone. This Indiana Oxidation Test is described inthe S. A. E. Journal, 34, 172-173 (1934). In service in a Diesel type engine,'this lubricating oil composition left the engine free from sludge or carbon deposits except for a slight discoloration of the piston just above the lowermost compression ring and adequately lubricated -the moving parts of the engine. The properties of this particular lubricating oil composition, as compared to that of the petroleum lubricating oil alone, as determined in one instance, were as follows:

Viscosity at 210 F., Ssybolt universal.

Seponiiication Number.

While the lubricating oil composition of the foregoing example embodies specifically a South Texas lubricating oil, my invention is also useful in lubricating oil compositions embodying petroleum lubricating oil from paraflin base crudes, asphaltic base crudes and mixed base crudes.

For some purposes, the properties of the compounded lubricating oil of my invention may be improved by stopping the saponiflcation of the phenyl stearic acid, or phenyl stearic acid mix ture, somewhat short of completion to produce a calcium phenyl stearate mixture including a minor proportion, 7% of the total mixture for example, of phenyl stearic acid and addingthis mixture including some unsaponifled phenyl 64.8seconds.

stearic acid to the petroleum lubricating oil inproportions ranging from about 0.5% up to about 2.5% by weight on the oil. The presence of unsaponified phenyl stearic acid in the mixture re duces any tendency of the compounding agent abnormally to increase the viscosity of the oil to which it is added, and may with some oils improve the viscosity index. The foregoing proportion of free phenyl stearic acid in the mixture is particularly advantageous; it may be usefully included in proportions up to about 20% of the total mixture. Instead of stopping the saponification short oi completion, tree phenyl stearic acid may be added to calcium phenyl stearate to produce similar mixtures.

While I predicate my invention upon the results obtained in its practical application, and not upon'any hypothesis, it now appears that the calcium soaps of aromatic stearic acids, generally, are useful for the purposes of my invention. Other aromatic stearic acids, tolyl stearic acid, xylyl stearic acid, naphthyl stearic acid, and anthracyl stearic acid for example, may be made by methods generally similar to the method above described for the production of phenyl stearic acid, and may similarly be saponifled with lime to produce the corresponding calcium soaps. The

presence of the aromatic group in the calcium soap seems to promote the solvent capacity of,

the lubricating oil composition with respect to sludge, and may assist in improving its thermal stability. Soaps of these organic acids containing an aromatic group also have the property of decomposing at a temperature approximating the end point, or carbonization temperature, of the petroleum lubricating oils used in the lubricating oil compositions of my invention. I do not at present know with certainty what if anyrelation may exist between this property and the proper ties of the improved lubricatingoils of my invention of rendering deposits of carbon and sludgewithin the engine soft and friable and disintegrating such deposits, butI believe them to be closely related to each other and to the bringing oi the calcium oxide equivalent oi the calcium soap into the regions within the engine in which such deposits occur and might otherwise remain in a form effective to give thelubricating oil composition of my invention these properties.

1. A liquid lubricating oil composition comprising a petroleum lubricating oil and calcium phenyl stearate.

2. A liquid'lubricating oil composition comprising a petroleumlubricating oil, calcium phenyl stearate and calcium stearate.

\ 3. A liquid lubricating oil composition comprising a petroleum lubricating oil, calcium phenyl stearate and phenyl stearic acid.

4. A liquid lubricating oil composition comprising s a petroleum lubricating oil calcium phenyl stearate, calcium stearate and phenyl stearic acid.

5. A liquid lubricatingoll composition comprising a petroleum lubricating oil and a calcium,

soap, of a stearicacidcontaining an aromatic group, said soap having a decomposition tempera- V ture approximating the end point of said oil.

.6. A. liquid lubricating oil-composition comprising a petroleum lubricating oil and a calcium soap oi anaromatic-stearw' acid v V,

' ARNOLD C. VOBA CH'.