US2337380A - Lubricating oil composition - Google Patents

Description

?atented Dec. 21, 1943 LUBRICATING on. coMrosrrmN Willard L. Finley, Edgewood Arsenal, Md., Milton Paul Kleinholz,

East

Chicago, Ind., and

Franklin M. Watkins, Chicago, Ill., asslgnors to Sinclair Refining Company, New York, N. Y., a corporation of Maine No Drawing. Application December 19, 1941,

Serial No. 423,694

4 Claims.

This invention relates to improvements in compounded petroleum lubricating oils. The improved lubricating oil compositions of the invention consist essentially of a petroleum oil base and an addition agent comprising a calcium salt of a dialkyl salicyclic acid amide, calcium diamyi salicylamide for example, the addition agent being present in an amount insuifleient materially to alter the normally liquid character of the petroleum lubricating oil itself, 0.5-5.0% on the oil for example. Thesecompounds have the following structure:

'( E-O Oil-Nut):

where R is an aliphatic chain of three or more carbon atoms.

The trend of development in internal combustion engines has imposed increasing burdens upon the oils used for their lubrication, particularly with respect to the operating temperatures and pressures. Extreme requirements in both of these respects are represented by the Diesel type of engine and supercharged aircraft engines. The useful operating life of a lubricating oil, in such severe services, is determined in a large measure by its thermal stability and by its physical capacity to continue functioning as a lubricant at the high temperatures and pressures encountered.

One measure of thermal stability is resistance tocompounded, a high solvent capacity for sludge of the character formed by oxidation of petroleum lubricating oils, and, perhaps of even greater-importance, the property of rendering deposits of sludge and "carbon" withinfthe engine soft and friable rather than hard and coherent and of disintegrating and removing such deposits as an incident of the normal operation of the engine. In engines of this type the high temperature to which lubricating oil is subjected, particularly at the top of the stroke, frequently causes deposition of sludge and earbonization in the groove for and behind one or more of the piston rings. Consequent sticking of the rings rapidly deprives, the piston and cylinder wall of proper lubrication inducing excessive wear and, frequently, scoring of the cylinder wall. The formation of 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.

In the lubricating compositions of the present invention the calcium dialkyl salicylamides function not only to inhibit sludge formation and to modify the character of the carbon" deposits, but they also function as strong anti-oxidants effective to reduce, at least over a prolonged induction period, the rate of oxygen absorption at elevated temperatures, thus rendering such lubricating oil compositions non-corrosive, or less corrosive, to alloy bearing metals. Moreover, these addition agents are compatible with known film strength agents such as chlorinated diphenyL' brominated diphenyl, sulphurized sperm oil, and the like. In lubricating oil blends including such film strength agents, the calcium dialkyl salicylamides inhibit the pro-oxidant effect that many of these film strength agents exert.

In applications of William L. Finley, Serial No. 368,992, filed December 7, 1940, and Serial No. 407,002, filed August 15, 1941, respectively, lubricatingcompositions are disclosed which include as addition agents calcium salts of normal and iso-alkyl esters of salicyciic acid. However, we have found that a lubricating composition including the calcium salt of a dialkyl salicylic acid amide is in certain respects superior to a lubricating composition comprising the same base oil and the calcium salt of an alkyl' ester of salicylic acid, particularly for service under extreme temperature conditions. This superiority apparently is due to the greater thermal stability of the calcium dialkyl salicylamides.

The greater thermal stability of the lubricating compositions of the present invention iswell illustrated by a comparison of two lubricating compositions compounded from the same base oil when heaetd at 500 F. for 45 minutes. The base oil used for these comparative tests was a twice solvent treated Pennsylvania bright stock having a viscosity of approximately 120 seconds at 210 F. Saybolt Universal. One of the lubricating compositions tested in this manner consisted of a sample of the base oil just d. scribed with 1% of calcium n-diamyl salicylamide incorporated therein. The other consisted of a sample of the same base oil with 1% of calcium iso-octyl salicylate incorporated therein. The heat treatment above described produced no visible precipitate in the oil containing calcium diamyl salicylamide whereas the oil containing the calcium iso-octyl salicylate became cloudy due to precipitation of decomposition products. Both blends were allowed to cool and were then filtered. The composition containing calcium diamyl salicylamide was found to have retained all of its original calcium whereas the composition containing the calcium iso-octyl salicylate was found to have retained only 26% of its original calcium content.

The oxidation inhibiting characteristics of the addition agents used in the compositions of the present invention are strikingly illustrated by comparison of the oxygen absorption rates of a blank base oil and of a sample of the same base oil having 3.5% calcium n-diamyl salicylamide incorporated therein. The base oil, in this case a solvent treated Pemisylvania type base oil having a viscosity rating of S. A. E. 30, when subjected to the oxygen absorption test at 400 F., absorbed oxygen at a rate of 16.3 cc. per minute per 100 grams of oil. Under the same test conditions the same base oil with 3.5% of calcium diamyl salicylamide incorporated therein absorbed oxygen at a rate of only 9.6 cc. per minute per 100 grams of oil.

The sludge dispersing properties of the addition agents employed in the lubricating oil compositions of the present invention are illustrated by a comparison of the results of the Indiana sludging test applied to samples of blank base oils and to samples of lubricating compositions compounded from the same base oils in accordance with the present invention. Thus the Indiana sludging time of a 30 S. A. E. petroleum lubricating oil stock derived from a South Texas crude was increased by the addition of 1.33% of calcium diamyl salicylamide from 12 hours for the blank oil to 52 hours for the compounded oil. Similarly, the Indiana sludging time for a 30 S. A. E. solvent-refined petroleum lubricating oil stock derived 'from a Pennsylvania type crude.

was increased by the addition of 1.33% of calcium diamyl salicylamide from 200 for the blank oil to 330 for the compounded oil.

The addition agents employed in the lubricating oil compositions of our invention may be prepared by first reacting salicylic acid with thionyl chloride in the presence of an aluminum chloride catalyst, thereby producing salicylic acid chloride, then reacting the calicylic acid chloride with the selected dialkyl amine to produce the corresponding dialkyl salicylic acid amide, and thereafter preparing the calcium salt either by direct reaction of the dialkyl salicylic acid amide with calcium hydroxide, preferably in admixture with at 30 in one instance and in least a portion of the eventual base oil, or by first reacting the dialkyl salicylic acid amide with sodium hydroxide in an alcohol-benzene solution to form the sodium phenolate and thereafter reacting the sodium phenolate with calcium chloride to form the calcium salt by double decomposition. The calcium dialkyl salicylic acid amides are easily soluble in oil, even in highly solvent refined parafiin base oils of high viscosity index, and they are more stable at high temperatures than other known salicylic acid derivatives.

The following example will serve to illustrate the preparation of a specific addition agent suitable for use in the lubircating oil composition of our invention. In this preparation 414 grams (3 mols) of salicylic acid were mixed with 848 grams (7.11 mols) of thionyl chloride to provide a large excess of the latter. Aluminum chloride (0.75 gram) was added as a catalyst and the mixture was allowed to react at 40 F. for seven hours. Excess thionyl chloride was then removed by distillation in a high vacuum so that the temperature did not exceed 50 C. The salicylic acid chloride which remained as a residue in this distillation was then filtered to remove the catalyst and any unreacted salicylic acid.

A-solution comprising 469.5 grams (3 mols) oi salicylic acid chloride prepared as above described in 500 cc. of dry benzene was slowly added to 950 grams (6 mols) of diamyl amine. The resulting mixture was cooled and rapidly stirred during addition of the benzene solution. After a. four hour reaction period an additional 500 cc. of benzene was added and the benzene layer was carefully washed with a dilute hydrochloric acid solution. Benzene was then removed by distillation and the diamyl alicylic acid amide was thereafter distilled at 320-350 F. under a pressure of 2 mm. of mercury.

A lubricating oil composition embodying our invention was prepared, from the diamyl salicylic acid amide obtained as above described, in the following manner: A concentrate containing 12% of calcium diamyl salicylamide first was prepared by placing in a flask equipped with a stirrer and an oil bath 352 grams of the base oil, a petroleum lubricating 011 stock having a viscosity rating of S. A. E. 30 derived from a Pennsylvania type crude. Calcium hydroxide (12 grams or .162 mol) was added to the oil and suspended in the oil by rapid stirring while heating the mixture to -190 F. 45 grams of the diamyl salicylic acid amide (.166 mol) and 2 grams of water were then added and the resulting mixture was stirred for 2 hours While continuing the heating. At the end of 2 hours the temperature of the mixture was increased to 280 F. to remove water and the mixture was then filtered to remove excess lime.- This concentrate was found to have a calcium content of 0.765% as compared to a theoretical calcium content of 0.81%. The concentrate thus produced finally was diluted with additional oil until the content of calcium diamyl salicylamide in the blend was. reduced to 1.33% by weight on the oil.

Two lubricating oil compositions embodying our invention were prepared by the above-described procedure from different base oils, the base oil comprising a Pennsylvania type lubricating oil stock having a viscosity rating of S. A. E. the other a lubricating oil stock of approximately the same viscosity derived from a Mid-Continent type crude. In each instance the blend contained 1.33% of the addition agent. Conventional laboratory tests, made on both of these lubricating compositions and on the lubricating oil stocks from which they were prepared, are given in the following table:

{ South Texas Pennsylvania ing a petroleum lubricating oil and as an addition agent a calcium salt of a dialkyl salicylic Type of base oil 1.33% 1.33% acid amide in which the alkyl groups contain at addm agent Blank 31 5 3 Blank 93 5 least 3 carbon atoms, the addition agent being salicylsalicylpresent in an amount sufiicient to improve the amide properties of the petroleum lubricating oil effecting its use as a lubricant but insuflicient mateggg S 35 35 2- 8 rially to alter the normally liquid character of r re IIIIIII;IFII 450 435 500 490 the petroleum lubricating oil.

$3. 2 253 2? 3 2 "32:2 2. A liquid lubricating oil composition com- Po B-lO 13-10 '5 0 15 prising a petroleum lubricating oil and calcium .iiiitfiffii: 132% Basic 1. 3% legit diamyl salicylamide; t calcium diamyl g Nitrqgen --Pe cent amide being present in an amount sufficient to gffgfig gg' a' improve the properties of the petroleum lubri- 32g eating oil effecting its use as a lubricant but insufvisosit at'fi'liEs'II e312 e312 7812 72.0 ficient materially to alter the normally liquid character of the petroleum lubricating oil.

Another sample of the diamyl salicylic acid ester prepared as above described was treated to form the sodium phenolate by reaction with sodium hydroxide in an alcohol-benzene solution. The calcium phenolate was then formed by reacting the sodium phenolate with calcium chloride. The calcium diamyl salicylamide thus formed was obtained as a residue by distilling off the benzene and alcohol. The final product was a reddish resinous solid which was easily soluble in substantial proportions even in oils of high viscosity index. Upon analysis, the reddish resinous solid was found to have a calcium content of Patent No. 2,537,580.

4.72%, a nitrogen content of 4.09% and a chlorine content of 0.37%.

We claim:

1. A liquid lubricating oil composition compris- 3. A liquid lubricating oil composition comprising a petroleum lubricating oil containing about 0.5-5.0% of a calcium salt of a dialkyl salicylic acid amide in which the alkyl groups contain at least 3 carbon atoms.

4. A liquid lubricating oil composition comprising a petroleum lubricating oil and as an addition agent about 0.5-5.0% calcium diamyl salicylamide.

WILLARD L. FINLEY. MILTON PAUL KLEINHOLZ. FRANKLIN M. WATKINS.

CERTIFICATE OF CORRECTION.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 2, first column, line 7, for "heaetd' read -heated-; line 70, for "calicylic acid" resid -salicylic acid--; second column, line 11;, for "lubiroating" readlubricating-; page 5, first column, line 17, in the table, third column thereof, for "0.1.5" read --.Ol 5--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of March, A. D. 19th.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,537,580. December 21, 191 .5.

WILLARD L. FINLEY,.ET AL.

It is hereby certified that error appears in the printed. specification of the above numbered patent requiring correction as follows Page 2, first column, line 7, for "heaetd" read -heated--- line 70, for "calicylic acid" 1 read -salicylic acid-; second column, line 114., for "lubircating" reed 1ubr.icating-- page}, first column, line 17, in the table, third column thereof, for "0.15" read --.oL; and that the said Letters Patent should be read with this correction therein that the same may conform to the rec- 0rd of the case in the Patent Office.

Signed and sealed this 28th day of March, A. D. 19%.

Leslie Frazer (Seal) Acting Commissioner of Patents.