March 22, 1960 L. W. SPROULE ET AL PHYSICAL COMBINATION OF CALCIUM AND LITHIUM 2,929,782 HYDROXY STEARATES FOR FORMING GREASES Filed July 17, 1957 38O 360 340 MIXTURE 32O 7– - APREPARED BY CO-SAPONFICATION 3OO 4O 6O 8O IOO % LITHIUM SOAP 6O 40 2O % CACUM SOAP Lorne W. Sproule inventors Worren C. Pottenden By 3 oz. Sizzlace-é Attorney 2,929,782 United States Patent Office Patented Mar. 22, 1960 2 These greases are valued for their high dropping points. 2,929,782 Their water resistance leaves something to be desired, the PHYSICAL COMBINATION OF CALCUM AND conventional calcium greases usually giving better service LITHIUM HYDROXY SEARATES FOR FORM in the presence of water. In order to use a minimum NG GREASES 5 amount of thickener in a grease, the lithium soaps must be prepared at a temperature above 400 F. Lorne W. Sproule, Sarnia, Lambton, Ontario, and War ren C. Pattenden, Courtright, Lambton, Ontario, Can Ca 12-hydroxy stearate greases have also been dis ada, assignors to Essa Research and Engineering Comic closed in the art, and are valued because they do not have pany, a corporation of Delaware to be plasticized with water. Their dropping points, O however, do not exceed 290 F., and they must be pre Application July 17, 1957, Seria No. 672,432 pared at relatively low temperatures in the order of 275 F. It has also been found, and this is believed to be un 3 Claims. (C. 252-40) appreciative by the art, that calcium 12-hydroxy stearate greases are very water sensitive. They will breakdown The present invention is concerned with improved 5 and fluidize in the presence of more than 0.4 wt. percent lubricating greases based on the use of a thickening water when worked at temperatures above about 190 F. amount of a novel "physical combination' of calcium and This is objectionable, for example, in equipment such as lithium 12-hydroxy stearates. food can closing units wherein the grease must lubricate This application is a continuation-in-part of Serial No. at 200 F. in the presence of condensed steam. 316,302, "Calcium-Lithium Hydroxy Fatty Acid Soap 20 From this knowledge of the art, it is believed that in Greases,' filed October 22, 1952, by the present inventors the present invention, it is unexpected that a superior and now abandoned. grease thickener comprising lithium and calcium soaps in brief compass, this invention proposes a lubricating in a novel physical combination could be prepared at a grease composition comprising a lubricating oil thickened relatively low temperature using only 20 wt. percent with a grease thickener formed at a temperature in the 25 lithium through the use of 12-hydroxy stearic acid in range of 275 to 315 F. by saponification of 12-hydroxy place of the unsubstituted acids. It has also been found stearic acid with a base comprising about 20% lithium that this novel physical combination permits a lesser hydroxide and 80% calcium hydroxide, so that the cal amount of total soap to be used in forming the grease. cium and lithium soaps are simultaneously formed in a This use of such a minor amount of lithium in the thick proper ratio to obtain a novel physical combination of 8 ener, the use of less thickener, and the lower manufactur the two soaps having properties unexpectedly different ing temperature, are very important from an economic from the known properties of the individual soaps. This standpoint, as will be appreciated by those skilled in the new physical combination of the soaps is an excellent art. grease thickener in itself, but it can also be combined with other conventional grease thickening soaps, especial One unexpected feature of this invention is that the ly with additional amounts of lithium 12-hydroxy stearate. water sensitivity of the calcium 12-hydroxy stearate As the art of grease manufacturing has become more grease is completely overcome by modifying it by phy sophisticated, it has been realized that greases having sically combining it with a minor amount of the lithium greatly improved properties over the simple Soap greases soap. It would have been expected that the lithium soap could be prepared by judicious combinations of different 40 would not improve the water sensitivity of the calcium basic materials, different soaps of perhaps different chain soap, because the latter is generally considered to be lengths, configuration and substituent groups, and/or superior in water resistance. For example, lithium oleate salts, either inorganic salts or salts of low molecular will practically dissolve in water, while calcium oleate weight carboxylic acids. Quite often it has been found will not. that such combinations of materials unexpectedly result Another unexpected feature of this invention is that in new types of thickeners, usually broadly termed "com this novel physical combination can be prepared at mod plexes,” which account for the improved properties of erate temperatures in the range of 275-315 F. This the grease products. These "complexes” often have prop is above the maximum temperature permissible in the erties, such as X-ray diffraction patterns, inconsistent manufacture of the calcium soaps, and well below the with a mere physical blend of the components and can be 50 high temperatures, 400 F. --, necessary to form the of many types. It is believed, for example, that the com lithium soaps. It would have been expected that, at plex formed between a C or higher carboxylic acid soap this lower temperature, the lithium soap molecules would arid calcium acetate at a temperature above 425 F. is of not have been sufficiently mobile to enter into a physical the ionic type, and results in a new crystalline soap struc combination. ture. “Chemical complexes” of various natures are be 55 It must be appreciated that this new physical combina lieved to be formed between low molecular weight di tion of the soaps cannot be arrived at by simple blend carboxylic acid salts and soaps. ing of the individual soaps, whether or not this is fol The art of grease manufacture has not evolved to a lowed by heating. An unsatisfactory product is obtained point where these complexes are so well known that the by simply blending the components. The two soaps must “tailor making of a product involves the simple selec be simultaneously formed by a co-saponification of the tion of known ingredients. Extensive experimentation 12-hydroxy stearic acid at a temperature in the range of and development are still called for, and quite often un 275°-315 F. in order to achieve the desired physical expected results are obtained. combination. The two saponifying agents can be added Mixed calcium and lithium stearate greases have been simultaneously to the acid solution, or one can be added known to the art. In order to make a satisfactory grease, 65 after the other, so long as the saponification bacause of the lithium component must be present in the thickener the first added agent is not substantially complete. The in an amount in excess of about 50 wt. percent, which two saponifying agents are preferably blended in plant makes the grease excessively expensive. These greases scale operations with the acid solution within 10 minutes also are deficient in their mechanical stability and oxida of each other. tion resistance. () The formation of the novel physical combination of Lithium 12-hydroxy stearate greases have also been soaps of this invention occurs uniquely at about a 20% known to the art, but are also excessively expensive. lithium soap content, although to permit a little latitude N- 3,929,782 3 4. this is given as being in the range of 18 to 22% in the was checked for free alkali and found to be 0.2%. This attached claims. Greater amounts of lithium soap do not was considered satisfactory. After heating at 290-300 cause the formation of further amounts of the physical F. for about 5 hours, the steam was turned off and the combination and the thickener partakes of the properties kettle contents allowed to cool. A test on the grease for of a blend between the 20% lithium/80% calcium physi water content at this stage was negative. While cooling cal combination, and the remaining lithium soap that is from 300 F. to about 200 F., 1181 pounds of mineral present. If a lesser amount of lithium soap is used, say oil were slowly added, along with 10 pounds of phenyl 15 wt. percent, the calcium 12-hydroxy stearate is not alpha-naphthylamine dissolved in 10 pounds of oil. The modified sufficiently to overcome the above described finished grease was drawn from the mixer into containers water sensitivity. O at 190 F. This grease required no milling. The com This invention will become clear from the following position and properties of the grease are summarized in examples and description with reference to the drawing - able , attached to and forming a part of this specification. The drawing is a graphical presentation of the relation Table I ship between the calcium and lithium ratio of the soap 5 Formula, percent by weight: and the worked penetration of the grease product, at a 12-hydroxy stearic acid------------------ O.8 total soap content of 10 wt. percent. This graph demon Lithium hydroxide monohydrate --------- 0.36 strates the formation of the novel physical combination Hydrated lime ------------------------ 1.26 of soaps of this invention. Mineral oil' -------------------------- 87.08 Greases in accordance with the present invention can Phenyl-alpha-naphthylamine ------------- 0.5 be prepared as follows: 12-hydroxy stearic acid or an equivalent material is charged to a grease kettle and heated therein to about 180°-200 F., preferably in the presence inspections: of an equal weight of lubricating oil, while stirring.