US2477296A

US2477296A - Lithium-aluminum soap lubricating grease and the method of making the same

Info

Publication number: US2477296A
Application number: US710947A
Authority: US
Inventors: Carl W Georgi
Original assignee: ENTPR OIL Co Inc
Current assignee: ENTERPRISE OIL COMPANY Inc; ENTPR OIL Co Inc
Priority date: 1946-11-19
Filing date: 1946-11-19
Publication date: 1949-07-26
Anticipated expiration: 1966-07-26

Description

Patented July 26, 1949 LITHIUM-ALUMINUM GREASE AND THE M THE SAME Carl W. Georgi, Eggertsville, N.

Enterprise Oil Company, Inc.,

SOAP LUBRICATING ETHOD OF MAKING Y., asslgnor to Bufl'alo, N. Y.

No Drawing. Application November 19, 1946,

' Serial No. 710,947

Claims.

This invention relates to lubricating grease compositions of the type which comprise a soap base compounded with a mineral oil, and to processes of making the same.

The three most commonly used types of lubricating greases have been those composed of sodium, calcium or aluminum soap bases compounded with mineral oils of various types and viscosities, depending upon the use to which the particular finished grease is to be put. Each of these three types of greases has certain advantages or desirable properties but also has certain disadvantages and limitations. Sodium base greases have the advantage of high melting points, usually exceeding 300 degrees F., but are subject to emuisification and washing when exposed to water or wet operating conditions. Calcium or aluminum base greases are resistant to emulsiflcation and washing by water but have quite low melting points in the order of 200 degrees F.

More recently certain other metal soaps have been used for preparation of lubricating greases, such as barium or lithium base greases, and which have the desirable combination of properties'of both high melting point and resistance to emulsiflcation by water. However, barium and lithium base greases have the disadvantages of expensive raw materials, dimculty of manufacture, and/or high soap base content for any given grease consistency grade.

It is an object of this invention to provide greases possessing combined advantageous properties of high melting point and good resistance to water emulsification, coupled with simplicity of manufacture, economical raw material costs and low soap base content for any given grade of grease consistency. Another object of this invention is to provide improved greases having a soap base comprising a complex lithium-aluminum salt or soap of fatty acids. A further object is to provide processes for preparing my improved complex lithium-aluminum soap base and for preparing finished greases containing same. Other objects and advantages of this invention will become evident in the following description and claims.

I have found that new and improved lubricating greases can be made by using as a soap base,

a complex lithium-aluminum soap of fatty acids in which the molecules of soap contain both the elements of lithium and aluminum. Any desired fatty acids may be employed in producing this soap base, such, for example, as stearic, palmitic or other fatty acids of either natural or synthetic origin, or mixtures of the same. I may use commercial stearic acid, which is largely a mixture of palmitic and stearic acids together with smaller percentages of saturated and unsaturated fatty acids of both lower and higher numbers of carbon atoms. I may also use hydrogenated fish oil fatty acids which are quite similar to commercial stearic acid in general characteristics and the term stearic acid or stearate is hereinafter used to designate any of these fatty acids.

In compounding greases according to this invention, the oil component may be selected and used from those petroleum and synthetic oils Which have heretofore been used in grease making, suchselection depending largely upon the particular application for which the finished grease is intended.

While aluminum stearate and lithium stearate base greases are well known and methods for their preparation well understood by those skilled in the art, I have discovered that greases prepared with my new and improved soap base possess very marked advantages over either aluminum base or lithium base greases or mixtures of the same.

I have round that these complex lithium aluminum soap bases may be made by reacting an 3 aluminum stearate, preferably an aluminum mono-stearate with lithium hydroxide, or by reacting a mixture of aluminum hydroxide and follows, it being understood that the term 'stearate as hereinafter used is intended to lithium hydroxide with a fatty acid. In either case, these complex lithium-aluminum soaps are formed in which both lithium and aluminum atoms are present in the soap molecules. These complex soaps ,when used in grease making, produce greases that are very superior to greases made by using mixtures of lithium soap and aluminum map} as will hereinafter be shown.

Referring in the first place to the making of these complex lithium-aluminum soaps by reacting an aluminum stearate with lithium hydroxide, the term "aluminum stearate" may refer to any one of three forms of aluminum soap, and in the equations herein used the symbol St represents any fatty acid radicle:

(a) A1(0H)2St=Aluminum mono-stearate (bl' AlHStz=Aluminum di-stearate (c) AlSta=Aluminum tri-stearate Commercial aluminum stearates used for grease making are often mixtures of two or more of the above, although quite pure forms of each of the three varieties are also available. I have discovered that lithium hydroxide will react with aluminum mono-stearate to form a complex double metal soap base, apparently in accord with the following equation:

Twopossible additional reactions suggested by the foregoing are:

' Reactions 2 and 3' either do not carry to completion or else-are not as effective for grease bases as reaction 1 and aluminum tri-stearate does not appear to be usable for carrying out my invention. v In Examples 1, 2 and 3, I have prepared greases using the reactions 1, 2 and 3 above referred to. 'Thegreases in these examples were prepared as apply to any fatty acid customarily used for grease making.

The aluminum stearate. lithium hydroxide mono-hydrate, water, and a portion of mineral oil approximately equal to the weight of the aluminum ,stearate were charged into a grease making kettle. The water may be omitted or smaller quantities thereof may be used, but I have found that stiffer greases can be developed when at least some water is used in the initial kettle charge. These ingredients were thoroughly mixed cold by agitating for several minutes, after which heating was started. The tempera ture of the batch was increased cautiously until I most of the water was boiled off and frothing and steaming had substantially ceased, after which the temperature was raised to about 300 degrees F. The balance of mineral oil required in the final grease was then added slowly with the heating contlnued, such that the temperature of the batch was about 400 degrees F., after all of the mineral oil had been introduced. The batch was then maintained at about 400 degrees to 420 degrees F. for one to three hours, after which it was drawn ofl into shallow pans and allowed to cool. After thorough cooling to about atmospheric temperature, the grease was worked or milled in the same manner customarily used in making many types and kinds of greases. Similar results can be obtained by charging into the kettle the correct mole proportions of stearic acid, aluminum hydroxide and lithium hydroxide, with or without a portion of the mineral oil, as described in detail in subsequent paragraphs. The grease of Example 2 was made by the same procedure as above described, except that twice as much lithium hydroxide mono-hydrate was used as in Example 1 and a somewhat larger quantity of water, so that the reaction mixture contained two mole equivalents of lithium hydroxide per mole of aluminum mono-stearate.

The grease of Example 3 was made by utilizing one mole equivalent of commercial aluminum di-stearate per mole of lithium hydroxide monohydrate. Otherwise the three batches were as nearly identical as possible. In all of these examples the heating is not suflicient to came oxidation of the soaps. as will be obvious to those skilled in the art. The following table shows the ingredients used and also test data on the three greases:

Exam pie 1 2 3 Soap lmole 'Al Mono Steamte per lmoleAlMono Stearate per 1 mole Al Di Stearate per 1 mole Ll Hydroxide (per 2mole Li Hydroxide (per 1 mole Li Hydroxide (per Equation 1). Equation 2). Equation 3).

, Formula, Pam bi Weight Al Mono Stearate (Mailincr'odt A1 Stearate M)--- 400 40 Al Di Stearate-(Mailincrodt Al 8t Di 40m Water 250 450 150.

Lithium H xide Monohydnite 48.7-- 97.4 27.5. 300 See. S. U. 6 1?. Mineral Oil 5,300-- 5,300 5,300.

Approx. Per Cent Soap Base in Finished Grease-- 7 1 7 .2.- 7.1.

' Tom on Eniiltddreaie Worked Gonsistencg (ASTM Method D-2i7) 331 Droppingloint (A TM Method 13-566 360 F 330 F. Free Aci or Alkali (ASTM Method.D-l28).--.-. 3% Free Acid 1% Free Alb 2.9% Free Acid. appear-mm Smootgieggussgy, unctuous, Soft, grainy, tendedtoblecd. Soft, soupy, tended to bleed.

' non- Resistance to Emnlsiflcation and Washing by Good Goo Good. I Water. Strip Teatlf i The grease made according to Example 1, wherein my complex lithium-aluminum soap was prepared by reaction of one mole commercial aluminum mono-stearate and one mole commercial lithium hydroxide monohydrate, was of stiff consistency, and smooth, glossy and unctuous in character. The grease made according to Example 2 and utilizing two moles of lithium hydroxide per mole of aluminum mono-stearate was much softer in consistency and of somewhat grainy, unstable character. It also contained an appreciable concentration of free alkali which was probably unreacted lithium hydroxide. The grease of Example 3 was still softer in consistency, of poor texture and stability and contained a large amount of free fatty acid. It is possible that a partial rearrangement of the ingredients occurred such that a mixture of aluminum mono-stearate, lithium stearate, free stearic acid and/or some complex lithium-aluminum soap base resulted rather than a lithiumaluminum di-stearate soap as suggested by Equation 3;

The tests of the greases made according to Example 1, 2 and 3 show clearly that the grease Greases having good resistance to emulsiflcaw tion and washing by water will show practically no change in appearance or condition, will remain adherent on the metal strip and the hot 5 water will not be oily or cloudy. Greases having poor water resistance will, on the other hand, be washed more or less completely off the metal strip and the water will be oily or milky from emulsified oil and soap base.

Results secured by this strip test method show that greases made with aluminum, calcium, lithium and my improved complex lithium-aluminum base soaps have good resistance to emulsiilcation and washing. The grease on the metal strip remains practically unchanged and the water is clear and free from oil. However, grease made with a sodium base soap has very poor resistance to water. Practically all of the grease is washed off the metal strip and the water becomes milky due to emulsified soap and oil.

I have also found that the most effective lithium-aluminum soap bases are made by reaction of approximatel 1 mole aluminum monostearateand 1 mole lithium hydroxide as illustrated by the following examples:

Example 4 5 6 I 7 Soap Base .5 Mole Li Hydroxide 1.1 Mole Li Hydrox- 1.25 Mole Li Hydrox- 1,5 Mol LiH d perlmole Al Mono ide per 1 mole Al ide per 1 mole Al e per 1 mole Al St. Mono St. Mono St. Mono St.

Formula, Parts By Weight Al Mono Stearate 400 400 400. Li Hydroxide Mono Hydrate 53.6 73.1. Water 250 350. 300 Sec. 8. S. U.@ 100 F. Mineral O 5,300 5,300 Approx. Per cent Soap Base in Finished 7.1 7.2.

Grease.

Tests on Finished Grease Worked consistency (ASTM Method D- 430 273 305 300'.

21 Dropping Point (ASTMMethod D566) 300 F 365 F 360 F 3 Free Acid or Alkali (ASTM Method D- 2.5% Free Acid 05% Free Alkali .11% Free alkali 3% Free alkali.

128). Appearance Smooth, soft and Slightly grainybutstifi Slightly grainy, soft, Grainy, sort consistsoupy. consistency and consistency, nonency tended to nonbleeding. bleeding. blee Resistance to Emulsification and Washing Fair Good Good Good.

by Water Strip Test.

made according to Example 1 is decidedly superior to those made according to Examples 2and 3.

All of the greases per Examples 1, 2 and 3 possessed good resistance to emulsification and washing by water. One method I use to evaluate this property is the so-called strip test, which is conducted as follows:

6 A polished metal strip about inch Wide by 4 inches long and 1% inch thick is coated on one side with a thin layer of the grease to be tested, the layer being in the order of 1 5 inch thick. The grease coated metal strip is then inserted in a small beaker of water such that about onehalf the length of the strip is immersed. The beaker and contents are then placed on a steam bath or hot plate and heated to the point of incipient or gentle boiling. It is preferable to raise the temperature rather gradually such that the time required to reach incipient boiling is in the order of fifteen to thirty minutes. When this point is reached the beaker and its contents are removed from the heating plate and examined.

The greases in Examples 4, 5, 6 and 7 were 5 prepared in substantially the same manner as Examples 1, 2 and 3. It will be noted that the formulae utilizing either appreciably less or appreciably more lithium hydroxide than 1 mole per mole of aluminum mono-stearate were ma- 0 terially softer in consistency and of relatively poor stability as to resistance to separation or bleeding. I have found, furthermore that my improved lithium-aluminum base greases which contain appreciable concentrations of free alkali, which results from substantially greater amounts of lithium hydroxide than the ratio of about 1 mole per 1 mole of aluminum mono-stearate, tend to be grainy in texture and relatively poor in resistance to separation and bleeding. I prefer accordingly, to utilize fromabout .8 to 1.1 mole lithium hydroxide permole of aluminum monostearate for preparing the Lithal soap bases, so that the finished greases will be substantially neutral or contain small amounts of free fatty 75 acid as indicated by titration according to Method 7 D-128 of the American Society for Testing Materials.

Instead of utilizing a commercial grade of aluminum mono-stearate, I have found it is possible to use other grades of commercial aluminum stearates which are commonly used for grease manufacture, and which are apparently mixtures of aluminum mono and di-stearates. Example 8 illustrates a lithium-aluminum base grease 8 to produce a finished grease which is substantially neutral or slightly acid by titration, it is thus possible to utilize various types of commercial aluminum stearates to manufacture my improved lithium aluminum base grease compositions.

To further establish the fact that the soap bases prepared according to my invention are actually complex double metal soap and not just a mixture of lithium stearate and aluminum prepared according to my invention from a comstearate, I made the following test batches:

Example 9 10 11 12 3 3p B e 1 mole Al Mono Steal-ate Aluminum Mono- LlHydroxide reactedwlth Aluminum Mono Stearate per 1 mole Li Hydrox- Stearate. omit- Stearic Acid to form Li plus Li Hydroxide reide. ting Li Hydrox- Stearate. N o Alumiacted separately with ide. num present. Stearic Acid to form Li Stearato.

Formula, Parts by Weight A1 Mono Stcarate Li Hydroxide Mono Hydrate Commercial Stearic Acid...-. Water 300Sec.S.S. U.@ 100 Mineral on 150 Sec. s. s. U. F. Steam 1:

Refined Stock.

mitates? e Base in tnrwifiiiefitf Tests on Finished Grease llao k igg nsistency (ASTM Meth- 278 375, bgpping Point (ASTM Method 372 F 345 F, Free Acid or Alkali (ASTM Meth- 23% 7 od D428) merciai aluminum steal-ate of this type. This product contained 10.5% A120: by analysis, indicating it was a mixture of approximately 25% aluminum di-stearate and 5% aluminum monostearate.

Example 8 Formula, Parts by Weight Commercial Al Stcarate, approximately 25% di and 75% monostearete Lithium Hydroxide Monohydrate 300 Sec. S S U. 100 F. Mineral 011.... 5,300. Water 300.

Approx. Percent Soap Base in Finished Grease 7.1

Tests on Finished Grease Worked Consistency (AS'IM Method D-2i7) 260. Dropping Point (AS'IM Method .3 Free Acid.

Appearance Smooth, glossy, stifi consistency, Stable and non bleeding.

Resistance to Emulsiiication and Washing by Water "Strip Test" Good.

The grease of Example 9 was made by substantially the same procedure as Example 1. The greases of Examples 10, 11 and 12 were prepared according to procedures customarily used for manufacture of typical aluminum soap base, lithium soap base and mixed aluminum soaplithium soap base greases respectively.

It is noteworthy that my improved lithiumaluminum soap base grease of Example 9 was considerably stiffer in consistency and of higher melting point than any of the other three greases, which would indicate formation of a different soap base structure than either lithium soap, alumium soap, or a mixture of lithium and aluminum soaps. Comparison of the formulae and finished grease properties of Examples 9 and 11 further indicates that grease soap bases prepared accordin to this invention are complex double metal soaps substantially in accord with Equation 1, and are not mere mixtures of lithium stearate and aluminum stearate.

In the preparation of my improved complex lithium-aluminum base greases by the reaction of aluminum hydroxide, lithium hydroxide and commercial stearicacid or similar fatty acid and attendant compounding with the selected lubricating oil constituent, I use a reactive form of gelatinous aluminum hydroxide containing approximately 16% AMOH): dispersed in water. Any reactive form of Al(OH): may be used in preparing my improved soap bases, the principal requirement being that the AMOH): be substantially pure and free of extraneous ingredients other than water and that it be sufficiently reactive to form soaps with fatty acids when processed according to the procedures described herein, and as per the following examples.

. Hydrogenated Fish ter Example 13 -14 1s 16 11 1s 19 Soap Base-Mole Ratios LiHydroxide 1.0 1.0 s .s .1 .7 .6.

Al Hydroxide- 1.0 .s 1.0 .a 1.0 .85 .ss.

FattyAcid 1.0 g 1.0. 1.0 1.0 1.0 1.0 1.0.

Formula. Parts by Weight Li Hydroxide Mono Hydrate Al Hydroxide (Dry Basis) w 011 Fatty Acids...

300 Sec. 8. S. U. 100 F. Mineral Oil... S. S. U. 210? Steam Refined Approx. percent Soap Base in Finished Grease.

Tests on Finished Grease Wfirirfid Consistency (ASTM Method 311 308 314 315 355 361 410. Dgggping Point (ASTM Method D- 360 F 356 F 355 F 357 F 335? F 340 F 330 F. I Free lcidorAllmlHASTM Method .OZFreeAl- .13 Free 5 Free .27 Free 1.0 Free 1.0 Free 1.5 Free D-l28). kall. Acid. Acid. Acid. Acid. A d. Acid. ResistancetoEmulsificatlonandWash- Good Good. Good Good Good Fair.

ing by Water "Strip Test."

the initial kettle charge. The above ingredients were mixed thoroughly cold by agitating for several minutes after which heating was started. The temperature of the batch was raised cautious- 1y until the water was largely boiled off and frothing and steaming had substantially ceased. If

excessive frothing and foaming of the batch occurred during this phase of processing, I added a silicone polymer having a viscosity of about 350 centistokes at 77 degrees F. in a concentration of about one to 100 parts of silicone polymer per 1,000,000 parts of soap base in the kettle, but this polymer may be omitted if desired. This polymer was found to minimize excessive frothing, foaming and expansion and to facilitate the heating and dehydration.

If the soap base became excessively stiff during this reaction and dehydration phase, small quantities of additional mineral oil were added to maintain the mass soft and pliable in the kettle. When the batch was substantially dehydrated, heating was continued until a temperature of about 400 F. was attained, whereupon the balance of the mineral oils was added as rapidly as possible while maintaining the batch temperature within a range of about .380 to 410 F. When all of the mineral oil was added, the batch was maintained at about 400 to 420 F. for one to three hours to complete the reaction and to assure a thoroughly homogeneous grease composition. The batch was then drawn off into shallow pans for cooling. After thorough cooling to about atmospheric temperature, the grease was worked or milled in the same manner customarily used in making many types and kinds of greases.

The greases per Examples 13 through 19 were all smooth, glossy, unctuous lubricants of excellent stability and freedom from separation or bleeding. It will be noted the ratios of aluminum hydroxide and lithium hydroxide-to fatty acid are not particularly critical and may be varied from about .8 mole aluminum hydroxide and .8 mole lithium hydroxide per 1 mole fatty acid to substantially 1 mole each of the two hydroxides per 1 mole of fatty acid. In this range, the finished point, as shown by Examples 17, 18 and 19. Since it is desirable to use the minimum concentration of soap base for any given consistency of finished grease, it is accordingly desirable to utilize hydroxide-fatty acid ratios of the order illustrated by Examples 13 through 16. The amount ofcomplex lithium-aluminum soap used will, of course vary, depending upon the consistency or degree of stiffness desired in the finished grease. From 3% up to 20% or more of the complex soap base may be used, the lower percentages yielding soft greases and higher percentages producing correspondingly stiffer or harder greases.

It will be apparent from the foregoing that another advantage of my lithium-aluminum soap base greases is their low soap content for any given finished consistency grade. By way of comparison, following are approximate soap base contents of typical varieties of greases of No. 2 consistency by the classification of the National Lubricating Grease Institute:

Many lubrication experts have pointed out that the oil constituent of lubricating greases provides the lubrication and that the soap base constituent serves primarily to maintain the lubricating oil in a non-fluid or drip-resistant state. Accordingly, in formulating lubricating greases it is desirable to have the maximum possible lubricating oil content and the minimum of soap base thickener for any given consistency grade. In addition, the fats.

fatty acids and alkalies required to form soap bases are appreciably more expensive than the lubricating oil constituents normally used in grease manufacture, so that a minimum of soap base for a given consistency grade of finished grease is of importance in economical grease manufacturing.

My lithium-aluminum soap greases accordingly possess the advantage of requiring mateterially lower soap base contents for a given consistency grade than is the case with other types of soap bases heretofore used. By proper formulation as required by the particular raw materials used, my lithium-aluminum soap base greases can be made in No. 2 N. L. G. I. consistency grade with about 6% to 9% lithium-aluminum soap; in No. 1 N. L. G. I. consistency grade with about 4 to 6% lithium-aluminum soap base; and in No. N. L. G. I. consistency grade with about 3 to lithium-aluminum soap base. Greases of stifler consistency than No. 2 grade may be made by incorporating cor-. respondingly higher concentrations of lithiumaluminum soap, so that the resulting grease may contain from 3% to 20% of lithium-aluminum soap base.

It will be apparent that the above concen trations of soap base for the respective consistency grades are exceptionally low compared to other soap bases heretofore used, and that my lithium-aluminum soap bases will accordingly provide greases having excellent lubricating properties as well as economical manufacturing 4 costs.

Another advantage of lithium-aluminum soap base greases lies in the fact that they are not difllcult to manufacture. The proportions of the various ingredients utilized to form the com- "plex soaps are not critical and a wide variety of oils of lubricatin viscosity may be utilized. Furthermore, the method of preparation is relatively simple and requires no special or unusual equipment other than that normally available in a reasonably well equipped grease manufacturing plant and the procedures for manufacture are essentially similar to those heretofore used for many years in making such greases as lithium base and aluminum base types. My lithium-alumimnn soap base greases are not particularly sensitive to cooling rate and may be drawn from the kettle into shallow pans in depths varying from about 1 inch up to 6 inches or more with little or no material effect on the properties and consistency of the finished greases. I have found that more rapid rates of cooling as provided by thinner layers in the cooling pans will sometimes produce greases of somewhat heavier consistency, but this difference is not great and there is little indication of crust ing, graininess or excessive oil separation with 6 the more rapid rates of cooling.

The relatively limited importance of cooling rate on the properties of lithium-aluminum soap base greases may allow them to be processed by continuous coolers or chillers, which have been been receiving considerable attention of late.

A further advantage of lithium-aluminum soap base greases lies in the fact they are substantially anhydrous and do not depend upon combined or free water for maintenance of the 7 12 ing or exceeding their melting points, and then cooled without being appreciably altered in structure, consistency and stability or freedom from separation.

A further advantage of my lithium-aluminum soap base greases is that they will prevent rusting of iron and steel parts lubricated therewith. This property is illustrated by the following tests: No. 204 size ball hearings were packed with various typical greases and were then operated for one hour at a speed of about 600 R. P. M. during which time a stream of water was splashed over the hearing so that the bearing and its contents of grease could become thoroughly admixed with water. Following this operation, the wet test bearings were stored in a humid atmosphere at room temperature for several weeks, after which they were examined. Following are typical test results:

Type of Grease (All No. 2 N. L. G. I. Consistency Grade) Bearing Conditions Calcinm'Base Aluminum Base..-

Bearings locked. Found to have badly rusted balls and races.

Bearings tree turning to slightly rough turning. Found to have scattered spots of pin point It is noteworthy that my lithium-aluminum soap base greases possess excellent rust preventing properties under wet operating conditions or humid storage. It is also noteworthy that although sodium base greases possess poor resistance to emulsiilcation and washing by water, they nevertheless do have good rust preventing properties, even when only small amounts of grease are left after operation in presence of water. Almost the exact reverse is true of the calcium and aluminum base greases.

To further evaluate the lubricating characteristics of my lithium-aluminum soap base greases, I ran tests according to the performance requirement of United States Army specification 2-1083, Grease, General Purpose, No. 2, and United States Army Ordnance Department tentative specification test procedure AXS-1574. This test procedure consists essentially of running the given grease sample for six hours at a temperature of about 220 F. in a test fixture which simulates the wheel bearing and hub assembly of an automotive vehicle. In such tests, my lithium-aluminum soap base greases performed satisfactorily, showing essentially no grease seepage or leakage from the test hub, adequate bearing lubrication, and no undesirable deterioration or breakdown of the grease itself. In this test my lithium-aluminum soap base greases of No. 2 N. L. G. I. consistency grade performed equally as well as the better types of sodium base, high temperature wheel bearing greases. By contrast, typical aluminum soap base, and calcium soap base greases of No. 2 N. L. G. I. consistency grade, when tested according to this procedure. melted, liquefied and leaked from the test hub to such an extent that grease was spattered over the interior of the cabinet enclosing the test apparatus.

I have conducted numerous additional tests on my lithium-aluminum soap base greases and have found they possess desirable properties equivalent to well made sodium base greases for lubrication of bearings and other mechanisms which are operated at elevated temperatures wherein calcium and aluminum base greases cannot be used because of their melting point limitations. I have also found that my lithium-aluminum soap base greases will perform at least as well and in some instances in a superior fashion to typica-lcalcium or aluminum base greases in applications which involve exposure to water and moisture, wherein sodium base greases do not perform satisfactorily because of their water resistance limitations.

In conclusion, it will be appreciated that the essential features of this invention relate to new and useful lubricating grease compositions which have an unusual combination of desirable properties including high melting points, resistance to washing and emulsification by water, and rust preventing properties; and which are anhydrous and thermally reversible. of low soap base content for a given consistency grade and hence economical in raw material cost; and which are relatively simple to manufacture and require no special or unusual equipment of a type not already common to grease manufacturing operations.

Although specific examples of compositions, methods of preparation and the like have been given, it will be appreciated that numerous modifications may be made which will not basically depart from this invention nor alter appreciably the end results.

Addition agents such as oxidation inhibitors, inorganic fillers, adhesiveness or string imparting agents, extreme pressure additives and the like may be incorporated in greases of this invention where it is desirable to impart special properties and in accord with such practices frequently followed heretofore in grease formulation and manufacture.

It will be obvious to those skilled in the art that numerous modifications of my methods of preparation of my improved complex lithiumaluminum soap base greases may be utilized without altering appreciably the end results. The methods of preparation are given as examples of a preferred means of production and are not intended to limit the scope of this invention.

I claim as my invention:

1. A lubricating grease composition comprising a lubricating oil compounded with a lithium-" aluminum soap of a saturated fatty acid selected from a group consisting of stearic acid, palmitic acid and hydrogenated fish oil fatty acids, said soap being the reaction product of substantially equal mole equivalents of aluminum hydroxide and said fatty acid and from one to two mole equivalents of lithium in the form of lithium hydroxide heated gradually to a temperature of about 300 F. in the presence of a quantity of mineral oil approximately equal in weight to the aluminum hydroxide-and fatty acid, said grease composition containing suiiicient lubricating oil added to said soap base and heated therewith from one to three hours to a temperature between 400 F. and 420 F. to form a final composition containing about 3% to 20% by weight of said soap base.

2. A grease composition according to claim 1, in which said soap is the reaction product of hydrous aluminum hydroxide, lithium hydroxide and said fatty acid.

3. A grease composition according to claim 1, in which said soap is the reaction product ,of a commercial grade of aluminum mono-stearate, and lithium hydroxide.

4. A grease composition according to claim 1,

in which said soap is. the reaction product of aluminum hydroxide, fatty acid and lithium hydroxide in the ratio of from 0.8 to 1.1 mole equivalents of lithium hydroxide and 0.8 -to 1.1 mole equivalents of aluminum hydroxide to one mole equivalent of fatty acid.

5. A process of making a grease composition comprising the steps of making a lithium-aluminum soap by reacting substantially one mole equivalent each of a saturated fatty acid selected from a. group consisting of stearic acid, palmitic acid and hydrogenated fish oil fatty acid, aluminum hydroxide and lithium hydroxide, by mixing the ingredients in the presence of a quantity of mineral oil approximately equal in weight to the aluminum hydroxide and fatty acid and gradually raising the temperature thereof to approximately 300 F., and gradually adding lubricating oil to the soap mixture while hot to produce a grease containing from 3% to 20% of said soap, and heating the resulting material to a temperature of from 400 F. to 420 F. for a timeinterval of one to three hours.

6. A process according to claim 5, in which the lithium-aluminum soap is prepared by reacting aluminum hydroxide, fatty acid and lithium hydroxide in the ratio of from .8 to 1.1 mole equivalent of lithium hydroxide and .8 to 1.1 mole equivalent of aluminum hydroxide per mole equivalent of fatty acid.

7. A process of making a grease composition comprising the steps of mixing a commercial grade of aluminum mono-stearate with lithium hydroxide in the mole ratios of from 0.8 to 1.1 mole of lithium hydroxide per mole of said aluminum stearate, heating said mixture of ingredients in the presence of a quantity of mineral oil approximately equal in weight to the aluminum stearate gradually to a temperature not materi ally exceeding 300 F., gradually adding lubricating oil to the reaction mixture while hot to produce a grease containing from 3% to 20% of said complex soap, and heating the resulting material to a temperature from 400 F. to 420 F. for a time interval of from one to three hours.

8. A process of making a grease composition comprising the steps of mixing a commercial grade of aluminum mono-stearate with lithium hydroxide in the ratios of from 0.8 to 1.1 mole of lithium hydroxide per mole of aluminum monostearate, together with a quantity of water, adding a quantity equal approximately to five times the weight of lithium hydroxide of mineral oil approximately equal to the weight of the aluminum stearate, heating the mixture gradually to form a, lithium-aluminum soap, and evaporating said water, said soap being heated to a temperature not exceeding 300 F., gradually adding lubricating oil to the reaction mixture whilehot to produce a grease containing from 3% to 20% of said soap, and heating the resulting material to a temperature of from 400 F. to 420 F. for a time interval of from one to three hours.

9. A process of making a grease composition comprising the steps of making a lithium-aluminum soap of a saturated fatty acid selected from a group consisting of stearic acid, palmitic acid and a hydrogenated fish oil fatty acid, by mixing the fatty acid with aluminum hydroxide and lithium hydroxide in the presence of a quantity of mineral oil approximately equal in weight to the aluminum hydroxide and fatty acid and gradually raising the temperature thereof to approximately 300 F., said soap being produced by reacting 0.8 to 1.1 mole equivalents each of alumiequal to about five times the weight oflithium 10 hydroxide to the mixture of fatty acid, aluminum hydroxide and lithium hydroxide before heating the same.

CARL W. GEORGI.

REFERENCES cn'nn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,363,013 MOIWB-Y et a1. Nov. 21, 1944 2,390,450 Morgan Dec. 4, 1945 2,406,655 Bax et a1. Aug. 2'7, 1946 2,417,429 McLennan Mar. 18. 194':