US2451039A - Lubricant - Google Patents

Description

Patented Oct. 12, 1948 Arnold J. Morway,

Clark Township,

Union County, and John C. Zimmer, Union, N. J assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 27, 1941, Serial No. 424,590

Claims.

The present invention is concerned with the production of improved lubricating grease compositions. The invention more particularly relates to a grease composition which is especially adapted for use under extreme variations in climatic conditions, such as wide variations in temperature and humidity. The preferred composition comprises a mineral oil base thickened to a grease consistency with a mixture'of saturated fatty acid soaps of lithium and aluminum It is known in the art to prepare various lu bricating grease compositions adapted for partic ular uses. The uses in which grease compositions are employed present a wide variety of conditions and generally a grease prepared with a given set of conditions in mind is not suitable for use under a difierent set of conditions. Airplanes are controlled in flight by special mechanisms such as rudders, elevators, and ailerons which are attached to the main portions of the airplane such as fuselage and wings by specially designed hinges. These hinges have metal to metal contact'bearing surfaces which offer a very difficult lubrication problem. Airplanes are operated under the most severe changes in climatic conditions and since the failure of even one part of the mechanism might well result in a catastrophe, it is imperative that all parts of the plane be maintained in as perfect a mechanical condition as possible. In order to be in good mechanical condition all movable parts should be free and well lubricated at all times. It is not uncommon for a plane during a single trip to be subjected to extremely high ground temperatures, subzero temperatures in the upperatmosphere as well as conditions of high humidity such as rain, snow, or ice.v Any lubricant used upon the control mechanisms of the plane must be capable of withstanding these conditions without disintegration.

High temperature greases such as the sodium soap greases are known to the art, however they are quite water-soluble and readily disintegrate under humid conditions. Water insoluble greases, such as the calcium soap greases, are also known, but these compositions will not withstand high temperatures. Aluminum soap greases are also water insoluble but have a relatively low transient point where they become fluid or rubbery and run or pull out of the bearing.

It is an object of this invention to produce a grease composition which will provide adequate lubrication at both high and low temperatures and will not decompose in the presence of excessive moisture. This and other objects will be apparent to those skilled in the art upon reading the following description.

The grease composition made in accordance with the present invention comprises essentially a low pour point lubricating mineral oil distillate, a lithium soap of a saturated fatty acid and an aluminum soap of a saturated fatty acid, although it is preferred to use from 10 to 20% of the lithium soap and from 0.25 to 2% of the aluminum soap based upon the total composition. A small amount of an anti-oxidant, say 0.2%, such as phenyl alpha naphthylamine, may be used if desired. 7

Although any of the numerous types of low pour point lubricating oils may be used as the base for compositions made in accordance with this invention, it is preferred to use a Coastal type oil having a viscosity, in the range of from about 58 seconds to seconds S. U. V. at 100 F. and a cold test below 40 F.

For the formation of the soap utilized in the production of the greases, any saturated fats or saturated fatty acids derived therefrom, such as stearin or stearic'acid may be used, although it is preferred to use the saturated acids derived from hydrogenated fish 011.

Any of the methods customarily employed in the compounding of greases may be used in the production of the compositions of this invention. The soaps may be produced separately and then mixed with the oil by heat and agitation; or preferably the saturated fat or fatty acid to be combined with the lithium may be dissolved in a portion of the lubricating oil by heating the oil sufficiently to dissolve the fat or acid in the oil, reacting thefat or fatty acid with lithium hydroxide and then the remainder of the lubricating oil having the aluminum soap dispersed therein may be added after which the mixture is brought to a clear solution and the water driven off by heating and stirring, the anti-oxidant added and the mixture permitted to cool. It is preferred to make the aluminum soap separately and then dissolve it in a portion of the lubricating oil although the aluminum soap can be produced from the saturated fatty acid and aluminum hydroxide in situ EXAMPLE 1 Percent Hydrogenated fish oil acids 13.00 Lithiumhydroxide (monohydrate) 2.00 Aluminum stearate 1 -i 0.50

Lubricating oil (low viscosity, low pour oil) 42.125 Lubricating oil (low pour Coastal oil) 42.125 Phenyl alpha naphthylamine 0.2

In compounding the above formula the acid and approximately one-fourth of. the oil are charged into a fire-heated kettle equipped with agitators. The mixture is then heated and stirred to a temperature of about 150 F, or until all the acid is melted and dissolved in the oil and then the lithium hydroxide dissolved in boiling water'is added to the acid-oil solution. Heating andagitation is continued and the temperature permitted to slowly rise until'all of the water is boiled ofi. During this continued heating small additional amounts of the oil are intermittently added. The aluminum soap is then dissolved in approximately one-fourth of the lubricating oil and this solution together with the remainder of the lubricating oilis-added to the kettle after the water has been boiled. off. The temperature of the kettle is then raised to within 'therange of from-350 to 400 F. or preferably about-370 R, at which temperature the grease is completely melted. The phenyl alpha .naphthylamine-is then added. after which agitation and heating is discontinued and the grease permitted to coolforming a smooth almost transparent block. The grease is then worked to a smooth paste in the kettle, filtered and packaged. The grease thus produced has the following characteristics:

A.S."T. M.worked penetration at77" F. 23'0 Melting point F. 374 Free acidity per 'cent 1 0.21

1 Calculated as oleic acid.

Low temperature testat 60 F.

:Test and-apparatus :described in paper presented .before the-44th annual meeting of the American Society for Testing Materials held :in Chicago, Illinois, 6/23-27 /41, Performance Specifications for Greases, Robert C. Adams and Harrison Patten.

Force to Approximate Time for 1 Turn 3 Bear- Torque Revolution ings Gins. Gms.-Cm. Secs.

EXAMPLEZ 100 parts of hydrogenated fish oil acids are neutralized with 15.73 parts of a lithium hydroxide (monohydrate) dissolved in Water. The resulting lithium soap is dried and powdered.

Percent Lithium soap (described above) 15.00 Aluminum stearate 0.60 Phenyl alpha naphthylamine 0.50 Lubricating oil (low pour,Coastal oil -40'F. pour point, 588. S. U. viscosity at 100 F.) 83.90

"The lithium soap and aluminum stearate are added to a fire-heated kettle, and one-fourth of the oil added. These ingredients are Worked to a smooth paste and the temperature raised to 300 F. The balance of the oil is added and the kettle covered and the temperature raised to 400 F. Stirring and heating is discontinued and the material cooled to room temperature. When cool the solid mass is worked to a smooth plastic homogeneous grease.

The physical properties of this product closely resemble those for the grease described inExample. 1.

What is claimed is:

1. Anlimproved lubricating grease composition comprising a major proportion of a low pour point lubricating mineral oil distillate, aminor proportion, sufiicient to thicken said oil to a grease consistencymf a lithium soap of a saturated fatty acid and an aluminum soap of a saturated fatty acid, said aluminum soap being present in an amount substantially smaller than that of said lithium soap but not less than 0.25% of the total composition.

.2. A composition as defined by claim 1, in which the lithium soap or a saturated fatty acid isthe lithium soap of hydrogenated 'fish oil acids.

.3.. Acomposition as definedby claim 1 in which the aluminumsoap is aluminum stearate.

4.. An improved lubricating grease composition comprising :a major proportion of a low pour point lubricating mineral oil distillate, a minor proportion ofa lithium soap of a saturatedfatty acid amounting to about'lO to 20% of thetotal compositionand a minor proportion of an aluminumsoa-pofa saturated fatty acid amounting to about 0.25 to 1% of theatotal composition.

5. A composition as defined by claim 1 in which said. low pour point mineral oil distillate is a low viscosity distillate,

ARNOLD J. MORWAY. JOHN 'C. ZIMMER.

REFERENCES 'CITED The following references are of record in the file .ofthis patent:

UNITED STATES PATENTS Number Name Date 1,989,196 I-Iil-liker Jane 29, 1935 2,024,990 Kaufman Dec.-17,.-1935 2,066,958 Brownback Jan. 5, 1937 2,186,514 Yagle Jan. 9,-1940 2,197,433 Lutz Apr. 16, 1940 2,274,673 Earle Mar. 3, 1942 2,293;052 Earle Aug. 18, 1942