US 2719826 A
Description (OCR text may contain errors)
2,719,826 g ALUMINUM SOAP GREASE coMPosmoNs Bruce W. Hotten, Orinda, Calif assignorto California Research Corporation, San Francisco, Calif., 11 corporation of Delaware 1 No Drawing. Application January 24, 1952,
Serial No. 268,135
9 Claims. (Cl. 252-18) This invention pertains to the use of a stabilized dispersionof calcium oxide or hydroxide. to enhance the anti-wear characteristics of an aluminum soap grease composition. 1 The'antiwear characteristics of aluminum soap (e. g., aluminum stearate and aluminum benzoate stearate) greases can be enhanced by dispersing calcium oxide or hydroxide therein, the dispersion being stabilized by a polyvalent metal sulfonate (e. g., calcium petroleum sulfonate).
Aluminum soap thickened greases are beneficially used where'it is essential to have grease compositions of high water-resistance. Normal aluminum soaps (e. g.,aluminun'i stearate) have a mild resistance to emulsification in water, but the normal aluminum soap greases are not beneficially used at high temperatures, such as above 160 F. Particularly efiective aluminum soaps which can be used to produce grease compositions having combined characteristics of high water-resistance and high melting points are the complex aluminum soaps, e. g., basic aluminum benzoate stearate.
In addition to the thickening agents, numerous secondary agents are incorporated in grease compositions to improve their resistance to oxidation, to improve their extreme pressure properties, to enhance their anti-wear characteristics, etc.
It' is a primary object of this invention to produce aluminum ,soap grease compositions having enhanced anti-wear, characteristics.
It is' an object of this invention to set forth a new class of anti-wear agents for grease compositions;
It is another object of this invention to prepare grease compositions havinginhibited wear characteristics.
It is also an object of this invention to provide a highmelting; water-resistant grease composition having enhanced anti-wear characteristics.
These'and further objects of this invention will be apparent from'the following description and the -ap- I pended claims.
According to this invention, it has been found that the anti-wear characteristics of aluminum soap grease compositionscan be enhanced by incorporating therein a dispersionof lime, said dispersion stabilized by-a polyvalent metal sulfonate.
The grease composition of this invention comprises, in particular,' an oil of lubricating viscosity, an aluminum soap thickening agent, calcium oxide and/or hydroxide, and a polyvalent metal sulfonate.
Suitable lubricating oils useful as base oils in the preparation of the greases thickened according to this in ventio ninclude a wide variety of oilssuch asnaphthenic base, parafiin base and mixed base mineral oils, synthetic-oils, e. g., alkylene oxide polymers such as polypropylene oxide polymers, and other hydrocarbon lubricants, e. g., lubricating oils-derived from coal products. Other synthetic oils include esters of alkylene oxide type polymers, e. g., acetylated propene oxide polymers prepared by acetylating propene oxide polymers containing 2,719,826 Patented .Oct. 4, 1955 2 esters.oi ;polyhydricqalcohol and liquid esters-of'acids of phosphorus and silicon. p 1 Al houg the anti-wear characteristics of: aluminum soap, greases in general areenhanced by incorporating therein. stable, dispersions of calcium oxide and/ or .hydroxid e, the anti-wear, characteristics.of grease composi: tionsthickened with. complex basic aluminum soaps are particularly enhanced by. dispersionsmi calcium oxide and/or hydroxide.
The. aluminum soapsused herein to thicken lubricating oils to the consistency -of..a grease include the normal aluminum soaps (e'. g., aluminum stearate) and complex basic aluminum soaps .(e. g.,, aluminum benzoate stearate). .7 Y w a 1 .-By ,complex basic aluminumsoaps. is meantthat the aluminum soap molecule-contains atleastone hydroxyl anion foreachaluminumcation, andat least two dissimilar anions substantially hydroca'rbonaceous inv character.
those anions whichlare composed mainly. of hydrogen and carbon, and include such anions 'which contain, in addition, minor amounts of. substituentssuch as oxygen, nitrogen,. etc.
'The' complex-basic aluminurnlsoaps are described in theHotten-Echols patent,applicationHSerialNo. 112,584,
has ,a greater solubility inlubricatingoil than another hydroxyl groups, 'dicarboxylic acid esters, polyesters,
organo anion. For purposes ofsimplification, theorgano anions of. greater ,oil 's olubility will be designated as relativey bleophilicfanions, f and the organo anions of lesser oil solubility will be designated as "relatively olet .,In order to characterize further the organo anions of thealuminum soapsof this invention, characteristic properties of each of the organo, anions are noted as follows:- .The aluminum divsoaps, of each of. the organo anions (i. e., the aluminum di-soaps of the oleophilic anion vand the aluminum di-soaps oLt he oleophobic anion) are in soluble in Wa er. For example, in th e 'alurninum-benzoate-stearate example of this: invention, the aluminum disoap of the benzoate anion-(inn, aluminum'di-benz'oate) andthe aluriiinurndi-soap of the stearate anion (i. e., aluminum, di-stearate) are insoluble in water.
The" aluminum di-soaps of the more soluble organo ani0nsj(i. e.,.the relatively oleophilic anions) are soluble in a petroleum hydrocarbon lubricating oil, (e. g., a Califoruia solvent-refined parafiinic oil having a viscosity of 485 ,SSUat F.) inan amount of at least 5% at 400 Thatlis, at 400, F., 5% of the aluminum soap of the oleophilic organo anion will form a true solution in a petrol'umihydrocarbon 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 l at 400 F. That-is, at 400 F., less than 1% (from 0% to about 1%) of 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 'the 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 By substantially. hydrocarbonaceous anions is meant units, each monomeric unit containing one aluminum atom having all of its valences satisfied byat least one 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. Inthe over-all averag 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-caprylate.
Suitable relatively oleophilic anions are anions of aliphatic (saturated and unsaturated), aromatic, aralkyl, and cycloaliphatic carboxylic acids. The acids must be sufficiently 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 phosphorus contain at least 14 carbon atoms, and more especially at least 20 carbon atoms, in the organo substituent. 'Ihe 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, lauri'c acid, myristic acid, palmitic acid, stearic acid, 12-
phenyl acetic acid, phenyl hydroxy stearic acid, arachidic acid, melissic acid, oleic I acid, linoleic 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 di-poly1 ropylen).=. benzene sulfonic acid),
'an alkane phosphonic acid having at least 24 carbon atoms in the alkane, group, cctyl thiophosphoric acid, ap t ic a tc.- e. te ric id, hydroxy stc i c pht en c a ds oi m lec lar weight above ab u 25.0, and. a yl b z ne l n ci h i g a le s ca b n atoms in he alky ub tvents a e Prefar d,
The relatively oleophobic anions are substantially hydrocarbon in structure and may be selected from ni n f l p c a rated an un atur e aromatic, aralkyl, alkaryl and cycloaliphatic monoand polycarboxylic acids. Acids having up to tw C rboxyl groups are preferred, 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 from 8 to 11 carbon atoms, and in some cases up to 20 carbon atoms, so long as the anion resulting therefrom is relatively oleophobic as compared to the 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 a alk-yl ca boay i ac d contain. a tal not more than 9 carbo at ms. p ef r bly a total o 7 arbon atoms-.
Suitable oleophobio anions are derived from benzoic acid, methyl benzoic acid, ethyl benzoic acid, toluic acid,
4 propionic acid, suberic acid, azelaieacid, sebacic acid, phthalic acid, salicylic acid, carboxy methyl cellulose, polyacrylic acid, etc. Of these, the benzoic, azelaic and toluic acids are preferred.
Examples of aluminum soaps which are effective thickening agents for grease compositions according to this invention include aluminum laurate, aluminum oleate, aluminum stearate, 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 steatatfi, aluminum benzoate hydroxy stearate, etc.
Polyvalent metal sulfonates are used to stabilize the dispersions of calcium oxide and hydroxide. These polyvalent metal sulfonate dispersants include calcium and barium salts of sulfonic acids derived from petroleum, polypropylene, polybutylene, and benzene or naphthalene alkylated with high molecular weight, oil-soluble hydrocarbon groups. The molecular weight of the hydrocarbon used in the preparation of the sulfonic acid ranges from about 350 to about 900. By petroleum sulfonate" is meant the mahogany sulfonates, as described in US. Patent 2,450,633.
Examples of suitable hydrocarbonaceous radicals which can be used to alkylate benzene or naphthalene are the following: dodecane, hexadecanc, eicosane, triacontane radicals; radicals derived from petroleum hydrocarbons, such as white oil, Wax, or olefin polymers (e. g., polypropylene and polybutylene, etc.). The sulfonic acids used in preparing the sulfonates of this invention also. include the oil-soluble sulfonic acids obtained from petroleum, such as mahogany acids," and the synthetic sulfonic acids prepared by various'methods of synthesis (e. g., sulfonic acids prepared by reacting a chlorinated white oil with benzene, using hydrofluoric acid as a catalyst, then treating the resulting white oil alkylated benzene with chlorosulfonic acid or fuming sulfuric acid, to form a white oil benzene sulfonic acid).
The dispersants (i. e. the polyvalent metal sulfonates) are used in amounts of 0.1% to 10%. by weight of the total composition. However, because. grease compositions containing from 0.3% to 2% of the dispersants markedly improve anti-wear characteristics, it is preferred to use these latter amounts. The amount of calcium oxide and hydroxide which can be stably dispersed in the lubricating oil depends upon the effectiveness of the particular dispersants used. 1 a percentage basis depending on the particular dispersant used, from 0.02% to 7% by weight of oxide or hydroxide can be dispersed .in the lubricating oil composition.
In addition to the above considerations, the type of base oil; of; the grease, will influence the amount of calcium oxide and hydroxide which is dispersible in the oil. For exa ple, a p y alent met l s lf n is m re sol le ina base oil of aromatic or naphthenic contentthan in a basev Oil having only a minor aromatic or naphthenic content. Therefore, a greater amount of calcium oxide or hydroxide can be dispersed in an oil, of high aromatic content.
In preparing the grease compositions of this invention, it is preferred to initially prepare a stable dispersion of calcium oxide or hydroxide in. a lubri at g l- T i dispersion of calcium oxide and/ or hydroxide in lubricating oil is then incorporated into an aluminum soaprthick ened grease in amounts sufficient to. enhance the, anti-wear characteristics of the aluminum soap greases.
The dispersion of calcium oxide and/or hydroxide lubricating oil can be prepared bythe method outlined in the Lindstrom and Woodrutf patent application Serial No. 203,783., filed December 30, 1950, now Patent No. 2,676,928. That is, colloidal dispersions (colloidal solutions) of calcium o ide a d/0r hy roxide in lubricati g oils can be obtain d by e use of. ihy ric al hol a 5.,
ethylene glycol. Calcium oxide or hydroxide is dissolved (or dispersed) in a dihydricalcohol. The dihydric alcohol solution (or dispersion) is then thoroughly blended with lubricating oil to form a' dispersionof calcium oxide or hydroxide in lubricating oil, which dispersion is then stabilized by a dispersant -(e. g.-," a" polyvalent metal sulfonate). The dihydric alcohol is removed by distillation, and the mixture is filtered to remove undispersed calcium oxide or hydroxide.
As set forth in the Woodrufi et al. patent application Serial No. 218,284, filed March 29, 1951, the filtration rate of dispersions of calcium oxide or hydroxide in lubricating oils can be increased by the use of alphahydroxy acids (e. g., glycolic acid, lactic acid, etc.) (or the calcium salts of these acids) in the preparation of the dispersions.
It isdesirable that the alpha-hydroxy acids (or the calcium salts thereof) be present in an amount such that the mol ratio of alpha-hydroxy acids (or the calcium salts thereof) to the calcium oxide (or hydroxide) dispersed has a value from about 0.1 to about 4.0.
The grease compositions of this invention can be prepared in the usual manner; for example, an aluminum soap and a lubricating oil can be heated, with agitation, then cooled to room temperature and the stabilized dispersion of calcium oxide and/or hydroxide in a lubricating oil can be incorporated into the aluminum soap grease. On the other hand, a stabilized dispersion of calcium oxide and/or hydroxide in oil may be incorporated into the grease prior to the heating step.
The data presented herein in Table I illustrate the eifectiveness of a stable dispersion of calcium oxide for enhancing the anti-wear characteristics (increasing the film strength) of a grease composition thickened with basic aluminum benzoate stearate. A calcium petroleum sulfonate was used as a dispersant to stabilize the calcium oxide dispersion. The film strength data were obtained with a slightly modified Almen test machine as described on page 145 in Lubricants and Lubrication by Clower, published by McGraw-Hill Book Co. in 1939. In the present test, the drill-rod journal was prepared from bronze. The data show the weight loss, in milligrams, of the bronze journal under a constant load of 8 pounds for a period of minutes.
1 Grease A contained 12% by weight of basic aluminum benzoate stearate, 32.3% by weight of a California solvent-refined parafiinic base oil having a viscosity of 480 SSU at 210 F., and 55.7% by weight of a Califo rri ia solvent-refined paraflinic base oil having a viscosity of 90 SSU at 210 1 Grease B" contained 11% aluminum stearate and 89% of a Cali iornia naphthenic base oil having a viscosity of 1100 SSU at 100 F.
1 A dispersion in oil of 2.6% calcium oxide stabilized with 20% calcium petroleum sulfonate, the dispersion containing 8.9% calcium glycolate used as an aid from the filtering step in the preparation of the dispersion.
4 A dispersion in oil of 1.2% calcium oxide stabilized with 20% calcium petroleum sulfonate, the dispersion containing 6.8% calcium lactate used as an aid for the filtering step in the preparation of the dis ersion.
5 A dispersion in oil of 1.7% calcium oxide stabilized with 20 0 calcium petroleum sulfonate. In the preparation of this dispersion. nothing was used to aid the filtration.
l The average of 2 test results.
7 The average 01 3 test results.
also enhance the anti-wear characteristics of aluminum soap greases In addition to' the components already noted herein, other agents may be incorporated into the greases; such' as rust inhibitors, oxidation inhibitors, corrosion inhibitors, extreme pressure agents, other anti Wea r agents, etc.
1. A grease composition comprising a major proportion of an'oil' of'lubricating viscosity, and aluminum soap in an amount suificient to thicken" said" oil to the consistency of a grease, from about 0.02%,vto about 7%,;by weight of an inorganic material selected from the group consisting of calcium oxide and calcium hydroxide, and from 0.1% to 10% by weight of an oil-soluble alkaline earth metal sulfonate, wherein said aluminum soap is a basic complex aluminum soap having at least two unlike organo anions, one of said organo anions being selected from the group consisting of aromatic monocarboxylic acid anions containing from 1 to 3 non-aromatic carbon atoms, and another of said organo anions being selected from the group consisting of monobasic aliphatic acid anions containing from 8 to 30 carbon atoms.
2. A grease composition comprising a major proportion of an oil of lubricating viscosity, a complex basic aluminum soap in an amount sufficient to thicken said oil to the consistency of a grease, from about 0.02% to about 7% by weight of an inorganic material selected from the group consisting of calcium oxide and calcium hydroxide, and from 0.1% to 10% by weight of an oil-soluble alkalineearth metal sulfonate, wherein said aluminum soap contains at least two unlike organo anions, one of said organo anions, the relatively oleophobic anion, being selected from the group consisting of aromatic carboxylic acid anions containing from 1 to 3 non-aromatic carbon atoms, and another of said organo anions, the relatively oleophilic anion, being selected from the group consisting of monobasic aliphatic acid anions containing from 8 to 30 carbon atoms, the mole ratio of said oleophobic anions to said relatively oleophilic anions having a value from about 0.2 to about 5.0.
3. The grease composition of claim 2, wherein the aluminum soap is a complex basic aluminum soap containing a plurality of anions derived from monobasic carboxylic acids, at least one of said carboxylic acids being an aromatic carboxylic acid containing from 1 to 3 non-aromatic carbon atoms, and another of said carboxylic acids being an aliphatic carboxylic acid containing from 12 to 18 carbon atoms.
4. The grease composition of claim 2, wherein the aluminum soap is aluminum benzoate stearate and wherein the inorganic material is calcium oxide.
5. The grease composition of claim 2, wherein the aluminum soap is aluminum benzoate stearat'e and wherein the inorganic material is calcium hydroxide.
6. The grease composition of claim 2, wherein the alkaline earth metal sulfonate is a calcium petroleum sulfonate.
7. A grease composition comprising a major proportion of an oil of lubricating viscosity, a complex basic aluminum soap in an amount sufl'icient to thicken said oil to the consistency of a grease, from about 0.02% to about 7% by weight of inorganic material selected from the group consisting of calcium oxide and calcium hydroxide, and from about 0.1% to about 10% by weight of an alkaline earth metal sulfonate, said aluminum soap having at least two unlike organo anions, one of said organo anions, the relatively oleophobic anion, being selected from the group consisting of aromatic carboxylic acid anions containing from 1 to 3 non-aromatic carbon atoms, and another of said organo anions being selected from the group consisting of aliphatic acid anions containing from 8 to 30 carbon atoms, the mole ratio of said aromatic carboxylic acid anions tovaliphatic acid anions having a value from 0.2 to about 5, said grease composition having incorporated therein a calcium salt of an alphahydroxy acid.
r atio of the said calcium salt of alphahydroxy acid to said inorganic material has a value from about 0.1 to about 4.0.
References Cited in the, file of this patent UNITED STATES PATENTS 2,079,051 Sullivan et a1. May 4, 1931 8 Campbell et. a1. Oct. 25, 19,49 Knowles et at. "m n..." Oct. 3 1, 19 50 Stross et a1. Apr 29, 1952, .Hotten June 10,1952 Cook Oct. 21,. 195 2 Beerbower et a1 Oct. 21, 1952