US2654710A

US2654710A - Polysiloxane-aluminum soap greases

Info

Publication number: US2654710A
Application number: US233113A
Authority: US
Inventors: Bruce W Hotten
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1951-06-22
Filing date: 1951-06-22
Publication date: 1953-10-06
Anticipated expiration: 1970-10-06
Also published as: GB721468A

Description

Patented Oct. 6, 1 953 PDLYSILOXANEeALUMINUM SOAP .GREASES Bruce Hottem-Qrinda, Calil-.,assignor to Ca'livfornia Research Corporation,

San Francisco,

Calif.,.a corporation of Delaware Noj'Drawing. ApplicationjJunejZQ, .1951, jSerial'No. 233,113

10 1 Claims. Cl. 2525373) 1 This invention pertains to a grease composition prepared from a polysiloxane (-e. g., methyl phenylipolysiloxane) and a complex basic aluminum soap; that is, this "invention pertains to the use of a complex basica'luminum soap as-a-grease thickening agent for a polysiloxane base-oil.

Not too long ago, the lubrication art was con- 'fronted with the problem of preparing grease compositions which could-be used at both low-and hig'htemperatures. It-was the inherent desire of the petroleum industry to prepare grease compositions With petroleum base oils, the petroleum ;oils"being as highly refined aspossible to increase the viscosity index to its maximum. However,

even with the *most highly refined petroleum :base oils, it has been diificult to prepare greases which give adequate lubrication-at extremely low and high temperatures.

Greases which are plas'tic at-high temperatures as well as low temperatures are useful in such severe variations of weather conditions as are encountered -in-airplane operations, in the opera- 'tion of military equipment in extreme cold weather and hot weather, etc. It is extremely advantageous to beable to use-one grease composition which is plastic at low and high temperatures, and is further characterized-by'ahigh resistance to emulsificat-ionin water.

Numerous synthetic oils have been placed upon the market inrecen-t 'years'to'satisfycertain-re qu'irements in thelubrication field. For example, a p'o'lysiloxane oil is normally useful under .extremely warm -or-co1-d conditions. The thick-ening'agents normally us'ed to thicken petroleum hydrocarbon oils to form greases are .disp'ersible in polysiloxane oils only with great 'difiiculty. .A

most successful method :found to disperse the normally used soaps .in polysiloxanes to form greasesinvolves a dispersal of the soap inavolatile hydrocarbon oil, then slowly working this soap dispersion into :a polysiloxane, after :which "the volatile hydrocarbon is removed by :distilla- 't'ion. This method, which is normally-usedi-n dis.- persing lithium soaps in polysiloxane :oils, is

cumbersome and unnecessarily costly. Furth'ermore,'the oxidation resistance of'the lithium soap 'thickened polysiloxane grease is not as great :as that which couldbe desired.

It is an object of this invention to prepare a grease composition which is serviceable at low and hightemperatures.

Itis another object ofthis invention-to prepare a po'lysiloxane base oil grease composition with considerably greater ease than has been :done heretofore.

It :is a still further object of this invention :to prepare a highly oxidation resistant polysiloxan'e base oil grease composition which can :be -.pre pared directly without-any "intermediate :steps involving additional solvents.

These and -further objects of this invention :will be apparent "from the following description and theappended-claims.

It has been discovered :that 'a grease composition resistant to emulsification in .water an dxuse- .ful at '=1ow and high temperatures :can be ;obtained by incorporating a polysil'oxane :oil :a complex basic aluminum soap containingat least two anions substantially organic in character, the aluminum soaps :of saidiorgano anions abeing water-insoluble and diiterent appreciably in the extent of their solubilities in "hydrocarbon-oils.

"The grease composition of this invention. comprises a polysiloxane base oil.andaecomplexrbasic aluminum soap.

'By fcomplex :basic aluminum soap is meant that the complex ial-uminum soap ;mo1ecu1e contains atleast onehydroxylanionforeach aluminum cation, and :at ileast two dissimilar anions substantially hydrocarbonaceous :in cha act The term f'essentially hydrocarbon (-substantially hydrocarbonaceous) means those radicals whichare composedzmainlyof hydrogen andcarbon, and :includessuch:radicals which contain, in addition, minor amounts of substituents such ,as chlorine, bromine, oxygen, ;.nitrogen, etc.

The polysiloxane hasez ls be repr sented by the formula indicative of -,the structure of a8 wherein It represents an alkyl radical containing no morethan :5 carbon atoms, R'-represents an aromatic radical, analkaryl radicalor-anaralkyl radical, and n, having a value of at least ll), represents the number of monomeric units present -'in the polymer. When R"is-a-n alkaryl radical .or an arallgyl radical, thealkyl groups attached to the aromatic "nucleus contain 110 more than 3 carbon atoms. It is particularly preferred that the polysiloxane base oil be -a methyl phenyl-polysiloxa-r1e; that i is; in the/above formula, R represents a methyl radical, :andtR" representsa phenyl radical.

"In the actual formation of a polysi1oxane,;a11:l of the monomeric-units may not havezthesame formula as that represented hereinabove. ,Eor example, "in some of j the monomeric omits. there may be two R radicals attached to the silicon atom; in other monomeric units, there may be two R, radicals attached to the silicon atom. However, the majority of the monomeric units are as represented in the above formula.

Examples of R radicals include the radicals derived from methane, ethane, propane, propene, butane, butene, pentane, pentene, etc.

Examples of R. radicals include the radicals derived from benzene, anthracene, phenyl methane, phenyl ethane, phenyl propane, methyl benzene, ethyl benzene, propyl benzene, etc.

The polysiloxane base oil is used as the major component of the composition of the present invention.

The organo anions or groups in the aluminum soaps of this invention are generally oleophilic (i. e., groups derived from or residues of acids, which are oil-soluble); however, one of the organo anions has a greater solubility in lubricating oil than another organo anion. For purposes of simplification of the discussion of the characteristics of the organo anions of the complex aluminum soap, the organo anions of greater oil solubility will be designated as relatively oleophilic anions, and the organo anions of lesser oil solubility will be designated as relatively oleophobic anions. That is, the organo acids of the relatively oleophilic anions are relatively oilsoluble, whil the organo acids of the relatively oleophobic anions are relatively oil-insoluble, i. e., less oil-soluble as compared to the oleophilic organo acids.

In order to characterize further the organo anions of the aluminum soaps of this invention, characteristic properties of each of the organo anions are noted as follows:

Th aluminum di-soaps of each of the organo anions (i. e., the aluminum di-soaps of the oleophilic anion and the aluminum di-soaps of the oleophobic anion) are insoluble in water. For example, in the aluminum-benzoate-stearate example of this invention, the aluminum di-soap oi the benzoate anion (i. e., aluminum di-benzoate) and the aluminum di-soap of the stearate anion (i. 6., aluminum di-stearate) are insoluble in water. The aluminum di-soaps of the more soluble organo am'ons (i. e., the relatively oleophilic anions) are soluble in a petroleum hydrocarbon lubricating oil (e. g., a California solvent-refined paraffinic oil having a viscosity of 485 SSU at 100 F.) in an amount of at least at 400 F. That is, at 400 F., 5% of the aluminum soap of the oleophilic organo anion will form a true solution in a petroleum hydrocarbon lubricating oil. On the other hand, the aluminum soaps of the less soluble organo anions (i. e., the relatively oleophobic anions) are soluble in a petroleum hydrocarbon lubricating oil in an amount of less than 1% at 400 F. That is, at 400 F., less than 1% (from 0% to about 1%) of the aluminum soap containing the oleophobic anions will dissolve in a petroleum hydrocarbon lubricating oil to form a true solution.

Furthermore, the aluminum soaps of the relatively oleophobic anions melt at a temperature above 400 F., and the aluminum soaps of th relatively oleophilic anions melt at a temperature less than 350 F.

The complex aluminum soaps of this invention are polymeric in structure, that is, the complex aluminum soaps have more than one aluminum atom and at least two dissimilar organo anions throughout the polymeric structure. It

is possible for the complex aluminum soaps to contain as many as 1,000 or more monomeric units, each monomeric unit containing one aluminum atom having all of its valences satisfied by at least on hydroxyl group and two organo anions. Thus, it is readily understood that although aluminum has a valence of +3, it is not meant herein to limit the complex aluminum soap of this invention to one containing only three specific anions. In the over-all average, the valence bonds of the aluminum atoms can be directed to more than three specific anions, that is, to more than one hydroxyl anion and more than two organo anions. The average molecule in the soap may contain a plurality of relatively oleophilic anions or a plurality of relatively oleophobic anions per aluminum atom. For example, it may be advantageous in some instances to use a complex aluminum soap as exemplified by aluminum benzoate-stearate-caprlyate.

Suitable relatively oleophilic anions are anions of aliphatic (saturated and unsaturated) aromatic, aralkyl, andcycloaliphatic carboxylic acids. The acids must be sufiiciently hydrocarbonaceous in character to impart the desired oil solubility. Thus, the aliphatic (saturated and unsaturated) carboxylic acids may contain from 8 to about 30 carbon atoms, preferably from 12 to 18 carbon atoms. The aliphatic substituent in the various cyclic carboxylic acids may contain at least 4 carbon atoms on the aliphatic group attached to the ring. The aralkyl, alkaryl and cycloaliphatic carboxylic acids preferably contain a total of about 16 carbon atoms. The relatively oleophilic anion may be an alkyl phenol containing at least 4 carbon atoms in the alkyl group, preferably 15 carbon atoms in the alkyl group; e. g., cetyl phenol. It is preferred that the organo-substituted acids of sulfur and phophorus contain at least 14 carbon atoms, and more especially at least 20 carbon atoms, in the organo substituent. The oleophilic acid anions may contain various substituents, such as hydroxy, amino, alkoxy, e. g., methoxy, and like radicals, so long as the anion remains substantially hydrocarbonaceous in character.

Examples of the carboxylic acids from which the oleophilic anions are derived are: caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, lZ-hydroxy stearic acid, arachidic acid, melissic acid, oleic acid, linolec acid, butyl benzoic acid, hexyl benzoic acid, octyl benzoic acid, dodecyl benzoic acid, phenyl butyric acid, phenyl hexanoic acid, phenyl decanoic acid, cetyl benzene sulfonic acid, a di-dodecyl benzene sulfonic acid (e. g., a dipolypropylene benzene sulfonic acid), an alkane phosphonic acid having at least 24 carbon atoms in the alkane group, cetyl thiophosphoric acid, naphthenic acids, etc. Of these, stearic acid, hydroxy stearic acids, naphthenic acids of molecular weight above about 250, and alkyl benzene sulfonic acids having at least 20 carbon atoms in the alkyl substituents are preferred.

The relatively oleophobic anions are substantially hydrocarbon in structure and may be selected from anions of aliphatic (saturated and unsaturated), aromatic, aralkyl, alkaryl and cycloaliphatic monoand polycarboxylic acids. Acids having up to two carboxyl groups are pre ferred, the monocarboxylic acids being especially preferred. For the desired properties, aliphatic monocarboxylic acids of 4 to 7 carbon atoms are employed. When the carboxylic acid contains 2 carboxyl groups, the acid contains at least 2 carbon atoms, preferably from 8 to 11 carbonatoms, and in some cases up to carbon .atoms, so long as the anion resulting therefrom is relatively oleophobic as compared tothe oleophilic anion employed. The alkyl groups of the aralkyl and alkaryl carboxylic acids contain no more than 3 carbon atoms. Thus, the alkaryl and the aralkyl carboxylic acids contain a total of not more than 9 carbon atoms,. preferably a total of 7 carbon atoms.

Suitable oleophobic anions are derived from benzoic acid, methyl \benzoic acid, ethyl benzoic acid, toluic acid, phenyl acetic acid, phenyl propionic acid, oxalic acid, malonio acid, isosuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, salicylic acid, carboxy methyl cellulose, polyacrylic acid, etc. Of these, the benzoic, azelaic and toluic acids are preferred.

Because of the increased effectiveness in obtaining a high melting, high water resistant grease, it is preferred that the oleophilic anion of the aluminum soap of this invention be an anion of an aliphatic carboxylic acid (e. g., stearic acid), and that the olephobic anion be an anion of an aromatic carboxylic acid (e. g., benzoic acid).

It is essential to the success of this invention that the more oil-soluble organo anion (i. e., the relatively oleophilic group) and the less oilsoluble organo anion (i. e., the relatively oleophobic group) be present in such proportions to each other that the complex aluminum soap of this invention will have the desired dispersibility in the base oil to bring about the formation of a grease structure.

When petroleum hydrocarbon oils are used as the base oils for greases thickened with the complex basic aluminum soaps of this invention, those greases become more gelatinous (i. e., increase in consistency) as the oleophobic-oleophilic anion ratio is decreased, Conversely, the grease compositions of this invention wherein polysiloxanes are used as the base oils increase in consistency (i. e., become more gelatinous) as the oleophobic-oleophilic anion ratio increases. The ratio of oleophobic to oleophilic anions in the average molecule of the soap may range from 1.0 to 10.0.

The ratio of oleophobic anion to oleophilic anion (on an average molecule basis) can be altered so that the desired grease structure may be obtained in polysiloxane oils of varying solvency characteristics. That is, it is generally desirable when using a polysiloxane oil of high solvent capacity to employ a basic aluminum soap which is less oil-soluble than the basic aluminum soap preferred when the polysiloxane oil is of a low solvent capacity. For example, when using a polysiloxane lubricating oil which is almost devoid of aromatic hydrocarbons, it is usually desirable to use a basic aluminum soap of this invention wherein the oleophilic anion is considerably more oil-soluble than the oleophobic anion. On the other hand, when using a polysiloxane lubricating oil having considerable quantities of aromatic hydrocarbons present, it is desirable to use a basic aluminum soap of this invention wherein the oleophilic anion is not too highly oil-soluble.

The number of free hydroxyl groups present in the basic aluminum soap of this invention may vary from 1.0 to 1:5 hydroxyl groups for each aluminum atom in the soap. When the number of .free hydroxyl groups present is less than about 1, the resulting aluminum soap is of a higher acidic character than normally is desired in greases. If the number of free hydroxyl groups reaches as high as 2 hydroxyl groups per aluminum atom, the grease prepared from such an aluminum soap is somewhat granular. Thus. it is preferred to use a basic aluminum soap of this invention wherein the free hydroxyl groups range from about 1 to about 1.5 hydroxyl groups per aluminum cation.

Although it is preferred to use oleophobic anions derived from carboxylic acids because ot the improved texture of the greases prepared therefrom, the relatively oleophobic anion may on the average be partly an anion of an inorganic acid of phosphorus, e. g., phosphoric acid, an inorganic acid of boron, e. g., boric acid, or in some cases an anion of inorganic acid of silicon, e. g., silicic acid. For example, the oleophobic anion portion of the average molecule may contain, in part, a phosphate '(PO4) anion. Furthermore, the relatively oleophobic anion may :be derived from phenol; that is, the relatively oleophobic anion may be an alkyl phenol containing no more than 3 carbon atoms in the alkyl group.

Examples of complex basic aluminum soaps of this invention are: aluminum benzoate stearate, aluminum benzoate oleate, aluminum -benzoate 12-hydroxy stearate, aluminum toluate stearate, aluminum benzoate naphthenate, aluminum benzoate hydrogenated rosin, aluminum benzoate sulfonate, aluminum azelate stearate, aluminum phosphate benzoate stearate, aluminum benzoate hydroxy stearate, etc. Of these, aluminum azelate stearate, aluminum toluate stearate, and aluminum benzoate stearate are preferred, the last being especially preferred.

The aluminum soaps of this invention can be prepared according to methods involving coprecipitation. For example, aqueous solutions of mixtures of the watersoluble soaps (e. g., sodium soaps) in the desired proportion of relatively oleophilic and relatively oleophobic anions are admixed with an aqueous solution of an alum'i-' num salt (e. g., aluminum sulfate). The resulting precipitate of the basic aluminum complex soap is then preferably purified to remove the salts such as sodium sulfate. Basic aluminum complex soaps yielding greases of high water resistance, high melting point and excellent chemical and physical stability may also be prepared in situ according to the method described in Jones Patent No. 2,469,041, wherein a 'fatty'acid (e. g., stearic acid), is added to a mineral oil solution of an aluminum alcoholate (e. g., aluminum butoxide), to form aluminum stearate.

The following examples illustrate the preparation of the complex aluminum soaps described herein:

Example 1.-The preparation of almnmum azelaic stearate .the B. group was a phenyl radical.

Example 2.Preparatiou of aluminum toluate stearate A mixture of 28.6 parts by weight of toluic acid containing a 2:1 mixture of the meta and para isomers, 27 parts by weight of commercial stearic acid, and 18 parts by weight of sodium hydroxide was dissolved in 400 parts by weight of water at about 180 F. This solution was slowly added, with stirring, to 50 parts by weight of aluminum sulfate octadeca-hydrate in 300 parts by weight of water at the same temperature. The resulting complex polyvalent metal soap was filtered, washed and dried as described in Example 1. On ashing, the soap left 13.9% A1203 (theoretical for the aluminum toluate stearate is 13.6%).

Example 3.-Preparation of aluminum benzoate stearate A mixture of 12.2 parts by weight of benzoic acid, 27.1 parts by Weight of commercial stearic acid and 16.8 parts by weight of potassium hydroxide was dissolved in about 500 parts by weight of water at 150 F., forming a clear solution. To this solution was added 33.3 parts by weight of aluminum sulfate octadecahydrate dissolved in about 300 parts by weight of water. The resulting aluminum benzoate stearate was obtained by filtering, washing and drying the precipitate as above in Example 1. On ashing, the soap left 11.6% A1203 (theoretical for AlC24H39O5=1L4 While the true basic aluminum complex soaps of the present invention produce greases having high water resistance and high melting points as well as excellent texture, physical mixtures of aluminum soaps from the relatively oleophilic acids, e. g., stearic acid, with aluminum soaps or the relatively oleophobic acids, e. g., benzoic acid, do vnot yield satisfactory greases, even though such mixture of soaps is exposed to prolonged heating. The complex basic aluminum soaps of this invention can be used in polysiloxanes to form grease compositions in amounts of from to 40%; however, it is preferred to use from to 35% by weight based on the finished composition.

The grease compositions of this invention can be prepared according to numerous processes. An advantageous process includes the addition of the complex basic aluminum soap to a polysiloxane at room temperatures and heating, with agitation, to temperatures ranging from 400 F. to 600 F., then cooling the mixture to room temperature.

The following Table I presents data to illustrate the efiect of (1) complex basic aluminum soap concentration, and (2) oleophobic anion/ oleophilic anion ratio on the texture and consistency of grease compositions of this invention.

The polysiloxane used as the base oil was a polymethylphenyl siloxane, wherein the R group in the above formula was a methyl radical and V This particularpolymethylphenyl siloxane is known as Dow Corning- 550 and has a boiling point of 250 C.

b olut ressure of less than 15 mm. of

mercury, a viscosity in the range of 300-400 SSU at F., a specific gravity of 1.08 (25 C./25 C.) a freezing point of -54 F., and a refractive index of 1.487. The complex basic aluminum soap was aluminum benzoate stearate. The soap concentration in the greases was 34% by weight based on the final composition. The greases were prepared by dispersing the aluminum benzoate stearate in the polysiloxane at temperatures ranging from 500 F. to 525 F., then cooling to room temperature.

TABLE I Benzoate/ stearate Ratio Consistency (ASTM Worked Penetration) In following Table II, data are presented to show the effect of the change in the relatively oleophobic anion. The complex basic aluminum soap used in this grease preparation was a basic aluminum toluate stearate having a toluate/ stearate ratio of 3.0. The base oil used was the same base oil as used in Table I, and the soap concentration was 32% by weight of the final composition. The grease was prepared by dispersing the soap in the polysiloxane at a temperature of 525 F., then cooling to room temperature.

TABLE II Consistency Soap Used gfafiggg Penetration) 1. o-toluate-stearate 283 2. p-toluate-stearate 382 TABLE III oleophobicl S Consistency Soap Used Oleophilic gg g gfigg Ratio Penetration) 1. Aluminum benzoate stearate 3. 0 30 296 In addition to the complex basic aluminum soaps, the polysiloxane base oils may contain other agents which increase the oxidation resistance still further, improve further the extreme pressure characteristics, etc.

I claim:

1. A grease composition comprising a major proportion of a polysiloxane base oil and a complex basic aluminum soap in an amount sufficient to thicken the polysiloxane base oil to the consistency of a grease, said complex basic aluminum soap having at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of at least at 400 F., and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of less than 1% at 400 F.

2. A grease composition comp-rising a major proportion of a polysiloxane oil and a complex basic aluminum soap in an amount suificient to thicken the polysiloxane oil to the consistency of a grease, said polysiloxane oil being derived from monosiloxanes containing alkyl radicals and aromatic radicals, said complex basic aluminum soap having at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of at least 5% at 400 F., and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of less than 1% at 400 F.

3. A grease composition comprising a major proportion of a polysiloxane oil and a complex basic aluminum soap in an amount suflicient to thicken the polysiloxane oil to the consistency of a grease, said polysiloxane oil being derived from monosiloxanes, the major proportion of which contains an alkyl radical and an aromatic radical, said complex basic aluminum soap having at least two unlike organo-anions, one organeanion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of at least 5% at 400 F., and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of less than 1 at 400 F.

4. The composition of claim 3, wherein the alkyl radical is a methyl radical, and the aromat ic radical is a phenyl radical.

5. A grease composition comprising a major proportion of a polysiloxane base oil of the formula wherein R represents an alkyl radical containing no more than 5 carbon atoms, R," represents a radical containing an aromatic nucleus, and n represents the number of monosiloxane units present in the polysiloxane, and a small amount, sufiicient to thicken the polysiloxane base oil to the consistency of a grease, of a complex basic aluminum soap, said complex basic aluminum soap having at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of at least 5% at 400 F., and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of less than 1% at 400 F.

6. A grease composition comprising a major proportion of a polysiloxane base oil of the formula henyl wherein n represents the number of monosiloxane units present in the polysiloxane base oil, and a small amount, sufiicient to thicken the polysiloxane base oil to the consistency of a grease, of a complex basic aluminum soap having at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of at least 5% at 400 F., and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by an oil solubility of less than 1% at 400 F.

7. A grease composition comprising a major portion of a methyl, phenyl-polysiloxane lubricatin oil and about to about 40% of a complex basic aluminum soap containing at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by a white oil solubility of at least 5% at 400 F. and another organo-anion derived from an organic acid, the aluminum (ii-soap of which acid is characterized by a white oil solubility of less than 1% at 400 F. substantially organic in character and differing appreciably in their solubilities in petroleum hydrocarbon oils, at least one anion being relatively oleophilic and another anion being relatively oleophobic.

8. A grease composition comprising a major portion of a methyl, phenyl-polysiloxane lubricating oil and about to about of a complex basic aluminum soap containing at least two unlike organo-anions, one organo-anion derived from an organic acid, the aluminum disoap of which acid is characterized by a white oil solubility of at least 5% at 400 F. and another organo-anion derived from an organic acid, the aluminum di-soap of which acid is characterized by a white oil solubility of less than 1% at 400 F. substantially organic in character and differing appreciably in their solubilities in petroleum hydrocarbon oils, at least one anion being relatively oleophilic and another anion being relatively oleophobic.

9. A grease composition comprising a major proportion of a methyl, phenyl-polysiloxane lubricating oil and about 15% to about of an aluminum benzoate stearate.

10. A grease composition comprising a major proportion of a methyl, phenyl-polysiloxane lubricating oil and about 25% to about 35% of an aluminum benzoate stearate.

BRUCE W. HOTTEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,186,346 Ricketts Jan. 9, 1940 2,223,127 Prutton Nov. 26, 1940 2,446,177 Hain Aug. 3, 1948 2,456,642 Merker Dec. 21, 1948 2,469,003 Rocchini May 3, 1949

Claims

1. A GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A POLYSILOXANE BASE OIL AND A COMPLEX BASIC ALUMINUM SOAP IN AN AMOUNT SUFFICIENT TO THICKEN THE POLYSILOXANE BASE OIL TO THE CONSISTENCY OF A GREASE, SAID COMPLEX BASIC ALUMINUM SOAP HAVING AT LEAST TWO UNLIKE ORGANO-ANIONS, ONE ORGANO-ANION DERIVED FROM ANORGANIC ACID, THE ALUMINUM DI-SOAP OF WHICH ACID IS CHARACTERIZED BY AN OIL SOLUBILITY OF AT LEAST 5% AT 400* F., AND ANOTHER ORGANO-ANION DERIVED FROM THE ORGANIC ACID, THE ALUMINUM DI-SOAP OF WHICH ACID IS CHARACTERIZED BY AN OIL SOLUBILITY OF LESS THAN 1% AT 400* F.