US2504717A - Reversible lubricating grease composition - Google Patents

Description

Patented Apr. 18, 1950 castes;

REVERSIBLE LUBRICATING GREASE COMPO SITIO-N Alillflid Js Morway,- Clark, and John cmzimmer,

Union, .N. 1., .assignors to Standard;

DgYBlOP a mentrCompana, a orpor tion. of. De aware N oDi-awingw Application September 32031947; Serial-No. 77553103 The ep resen-teiiwention-relates;tonalreversible.t

position-although fundamentally; they consist .of

soap; mixed-swith. ordinaryalubricating oil-.1 Both: that oilaandethe type andequantity e01 soap nmay be widely variedatomeet the acomiitions-of. a are ticular r lubrication zp roblern ,requiring the useof as semiefluido lubricants- Thee lubrication prob-, lems towhich thegreaselcompositions are-applied: are-:2 almost 1- as, numerous..- as the compositions: themselves. Oneetroublesomesproblem =presents itself -.witla-- the. attempttto .-lubrioate bearings on: v t t temperaturessin,,thee neighborhood;- of, theeboiling; point-.01. ,water; and, often above andespeciallv-those rhearings which; operate-at tome peratures tbetweenslimw 2x11113001 Fa" in the re eneeeofi waters. Gneasessfor;the most part. are-a1 either dispersions on; solutions, or; metallic. soaps: insaa-minerahmbricating oiLwhich will rangeeinsviscosity from 60s seconds Saybolt at 100 F. for the light oils toe-about ififluseconds; .Eiaylaoltsat-4100 F) for;theebrightsstockss The soaps ordinariiy usedavforrthermaking of greases consistbt ithewa1ka1inmetaL-:SOapS,- alkal-inmeartn, soaps k or. mixtures thereonz, Sometimes special soaps suchraszaluminumssoaps are-remplo-yed. Intheapreparationnotithe soaps am excess of themetal 1 is sometimes; employed which 1results= in the production of a basic soap. ln-tthe lubricae tiomoixbearingsoperating attempemturesaboi e 140 ithevordinary typengrleaseslaretfound to haveemany imperfectionsm For instance thellinel soap.greases..requixevtha.presencevor in orporate tiionaonagsmall amount .;0;Wa e1= athe compmw sitionlto secureetnevgreaserlike struaturel When. temperatures ,around. 2123] Bears obt ineds ha water present sin a ,lime ,so pr liease evaporates.

andvlthe limejsoap, which is ,insolublein the, .oil F 6:01am. ((31. zsz ssz:

theapresence of water they are s onidissolved outs and ,removed f1 Om. .the -bearing, W-ithuthe re;v moslalgof.,theesoam which Junctions.- to-hold the oil,,-the .oilt isnolonger retained inthe bearing It vhas:,.p 1 :eviousl; z -been =suggested thatagreasess might. be vpreparedsfrom bariumesoapss y In; gthes- Prior. art, however, difiicu1ty ,has, been; encoun teredr.sin"pteparing .stableesoapseor-,barium-.baSQs nd it has.be n he1.d sen.era11v hat only thabasios bariumsoaps, i. ,e-kthose; containing-an excess-otbariuml hydroxide, couldabe -g used-Vito prepare;

reases... Basic 4 barium, soap; reases; althoughe possessingarelatively high meltingipointsgofteng reachinaaslhi h aseooz depend n -u on h e amount and kindofnbasiczbarium soap; presentingv theoil losetheir-greasestructurewhensubiectggk tovtempelfatures ins thea neighborhood? of th eini melting pointsand revert vtoaa:mixturemfistnatim fled oillandz soap. Afterlthe melting-:point-mf was invention includes "as" one aspect a method of preparingva mechanically stable grease having the otherwise desirable properties ofbariumbasegreases-without using an excess of the barium' c oxide or hydroxide witlrit's accompanying disad-f 4 vantages:

Mixed alkaline earth soapgreases suchas are calcium-barium greases possess the faults of? bbth lime soap greases and the basic bariumsoap; greases. Aluminum soap greases although often" used in life-time bearings, tend to emulsify with water or become sem-ifi'uid and rubbery atele= vated temperatures,- such as above 140 F: and-Tor; these=reasons cannotbe retainedin a bearing;v operatingmnder such conditions; Since the re tention of fluid oil in a bearing ofiers mechanical? problems, it isapparent that the greases asabpve; described are notparticularlv adaptable to ,th eg lubrication of life time"bearings land that an irhproved grease devoid of-theseimperfectionsjsv especially desirable,

The. principal object of j this invention is the v en 1 1 a bari m s ansrea epf excellent tructures eesyo o.preparaaml which ssrev rsihle'e wa nres s udl hermellxjstebl ese andotherxoblectsa nts ianssa nt and mecha icall will be apparent to those skilled in the art upon reading the following description.

A further object of this invention is to compound barium soap greases in a manner which avoids the introduction of objectionable ingredients which appear to have given rise to diificulties encountered in prior art attempts to prepare barium base greases.

It has now been discovered that greases compounded of neutral and/or acid barium soaps and mineral lubricating oils produce greases which are water insoluble, transparent, mechanically and thermally stable and reversible, provided certain procedures are observed during their preparation. These greases can be used at any temperature up to 212 F. in the presence of water without decomposition and at. temperatures above the boiling point of water, not to exceed the ignition or decomposition temperature of the constituents themselves, and may be liquefied and solidified innumerable times without the loss of lubricating quality or grease structure.

' It appears that two special procedures are desirable in the preparation of mechanically stable barium greases having the otherdesirable properties mentioned above. In the first place it appears to be desirable to avoid the introduction of barium carbonate when the barium oxide or hydroxide is used as a saponifying agent. Apparently commercial barium oxide. or hydroxide, tends to react with carbon dioxide in the air over a period of time to revert to the somewhat more stable carbonate. If, a barium oxide which includes an appreciable quantity of the carbonate is employed in forming the grease, or in forming. the soa to be incorporated in grease. the diffic'ulties known to the prior art'in securing proper grease structure, mechanical stabilty, reversibility. etc., appear to arise. Hence it is desirable to'use either a freshly calcined barium oxide (or freshly hydrated oxide which has been kept away from the air since calcination) or to keep the calcined barium oxide in an inert atmosphere, for example in a nitrogen atmosphere, after cal cination.

A further requisite which appears to be quite essential to securing a good stable, reversible grease'structure, appears to be the formation of the soap. or the saponification of fatty material, direc ly in the mineral oil which is to serve as the liquid lubricating element of the finished grease com osition. The use of preformed soap has been found to be unsatisfactory and in fact it is commonly impossible to secure a grease structure at all when it is attempted to incorporate' a reformed barium soap into lubricating oil. This is particularly true with respect to the basic barium soaps used in the prior art. g

1y calcined by heating barium carbonate, or the impure oxide, to a sufiicient temperature to drive off the carbon dioxide. Barium carbonate is not easily decomposed but the calcination appears 4 to be facilitated by the addition of a small amount of carbon such as charcoal, carbon black or other carbonaceous materials, with heating to a fairly high temperature. In the absence of carbon or carbonaceous materials, it may be necessary to heat the carbonate to a temperature as high as 1350 C. if heating is carried out under atmospheric pressure. By using reduced pressures, and/or an atmosphere free from carbon dioxide, the temperature may be somewhat lower. In any case heating is carried out at a sufficiently elevated temperature and over a period sufiiciently extended to decompose substantially all of the carbonate and obtain a substantially pure oxide. Assuggested above, if the calcined oxide is not to be used promptly, it should be protected from access to air, preferably by storing it in a nitrogen atmosphere.

The barium oxide, preferably substantially free from the carbonate as mentioned above, may be hydrated to the hydroxide, preferably in an inert medium suchasoil, before adding the fatty maaqueous slurry to the soap stock in mineral oil solution. However, a fairly. pure commercial barium hydroxide appears to be satisfactory although it is preferred to use the freshly hydrated oxide. Conventional methods for grease'manufacture may be employed with the exception and the added advantage that after the soaps are completely formed and dispersed in the mineral oil the grease may be placed in final package containers and permitted to cool without the necessity of further working.

Preferably, the soap stock or fatty material is first dissolved by stirring it into at least a portion and preferably all of the lubricating oil, accompanied by heating, if necessary, to a temperature at least equal to the melting point of the soap stock. Thereafter, for a neutral soap grease the stoichiometrical proportions of hydrated barium oxide are added, or slightly less if an acid grease is desired. During the formation of the soap, the ingredients are heated. moderately, e. g., to a temperature around 200 F.v

erably may be the final shipping containers toavoid further handling.

The total amount of soap in the grease made in accordance with this invention will range from about 5% to about 50% by weight based upon the total grease composition depending upon the properties desired in the finished grease, the:

type and viscosity of the oil used and the character of the fat or acid employed in the produc tion of the soap. Y

Although a wide range of lubricating oils may be employed as the lubricant in the grease, in general the base oil comprises an oil having a S. U. V. in the range of from about 35 to 220 seconds at 210 F. However, forthe production of most greases of the type contemplated by this;

invention it is preferred to use a base oil having a viscosity of from to 2400 at 100 F.

The usual types of soap stocks, such as animal or vegetable fats or commercial stearic, palmitic,

and oleic acids, as well as fatty acids split from hydrogenated fats such as hydrogenated fish oil acids, which soap stocks contain at least 12 car,-' bon atoms to the molecule, usually 12 to 22 or 24 oarborratornsr may 'fie used' for tiie production of tlie soaps' usenit for'the -purposes of tiii's" ira/en tion: Other-additives such as anti oxidants," ad liesives and rust preventing agents may' be" in corpoiattachwitldvsmt departing 'from tlie scope oi' use invention. 7

The" fdilowing exanmlswill I serveasfiliustra tionsoftypicalcompositions accordiiigfi to'this in ventinr- 10.00 %;by; weight .commercialoleic. acid- 8.0!? byyweight i barium hydroxidee eil mixtu-re 81.93 by; weighttlubricating oils (1cw.;cold..test

coastal ltypeioil) BSA/ m; (retainedbarium o xi'dg. 332 91,?

The oleiciacid'ian'dethechomogeneoustemulsiorr Exampte z i A'hardergrease was prepared'b'y' the samegen' eral method asitl'iatiirrrEiiamplesli using the following.,. ingredients- Percentages 1 given are .by weight;v as in Eiiampll. 1'.

znifaicommer'cialioleici acids l95/5i-bazriuicd'il'l'ydrcside on1mixturv 61%.1lubricatingroi1 i( lowa'colrl .tc'st coastal) 1 28.5% calcined"bari1im" oxid; 2835 70" Water, 4320 7 0 lubricating o An excellent hard grease resulted which ran for 1 hour in the Annular Bearing Engineers Committee test machine at temperatures above 230 F, with no leakage and with good lubrication. The grease showed some tendency to ball up and to become somewhat brittle at temperatures above 200 F. This grease, which con tains less mineral oil than that of Example 1, appears to be particularly suitable Where a hard grease is needed for service at moderate temperatures.

Example 3 The grease of Example 2 was modified by incorporating additional 011 and a small amount of an aluminum soap. Thus 2 grams of aluminum stearate were slurried with 48 grams of mineral lubricating oil and the slurry was added to 200 grams of the grease. The mixture was heated to the melting point and thereafter cooled slowly. An excellent product of homogeneous structure was obtained.

Example 4 20.00% hydrogenated fish oil acids 19.00% barium hydroxide-oil mixture 1 61.00% low cold test coastal type lubricating oil 28.5% calcined barium oxide, 28.5% Water, 43.0%

lubricating oil.

The grease was made according to the procedure outlined in Example 1 above, resulting in a product having a penetration of 265/280 at 77 F. and a melting point of 250 F. The charone" However: when again cooled to-be1ow the 'boilin'gF point of water thegrease will turn to a smoothlromogenecusflubricantf- With reference=--to-the barium compounds,- it appears" that trie calcined bariurn' oxide is more-active "than" commercial "b arium hydroxide, probamy because of the presence of perceptiblequantitis of bariumcarb'o'nate in the latterr For this" reason i it is preferred-" to hydrate? the oxid'e freslily' irrthe" absence of carbon dioxid' a The" hydraticrr' oil, as suggested 1 above; convenient way to 1 exclu'dcarbon dioxide but there-"are various other waysof excludingit: as will be"-apparent to*those skilled ifith'e a-r It appears-to bedesirableto "use an excess' of watihydrating and; as-=indicatedfabovei there suiting soap is preferably neutralor siightly-acidifeapHatleastas low'as 7.0. 7

The expr'essiorr consisting essentiallyfias used er the claims; meansthat the composition is up-substantiauy entirel of"theingredints recited. and that such irigredintsmre==tlie=niaiff ones' an'd tnose wnich characterize tiie compesition; This does-'notexclude minorcuantitis ofother" conventional ingredients? are rela irtsuch small. quantities that"th'e essentia'l' prop erties of the comp osition" are substantially u -1- affected.

While specific procedures and tem eratures havdbeenrecite'd inthe foregoing*'examp1es;.it will he? understood that these may be varied somewhat? Slow cooling. of the" barium greases appears to beessen'tial: hence-the process *is-znot as"satisfactorilyfconducted with fast 'coolingfcoii tiriuou's" process apparatus." Citherwisefthe" com tinnous roeesv appears some applicable: Iir general the barium soaps "will comprise prefer ably from 15 to about by weight of the greases, but greases having soap content of 5 to may be prepared satisfactori1y. The addition of a small amount of aluminum 'soap, e. g. aluminum stearate, tends to make a smoother and more homogeneous product. The alum num soap is preferably employed in proportions of 0.2 to 4% by weight, based on the total composition, but very satisfactory grease may be prepared without its use.

We claim:

1. An anhydrous, reversible lubricating grease composition consisting essentially of 50 to by weight, based on the total composition, of a low cold test mineral oil thickened to a smooth homogeneous solid grease structure with 10 to 50% of barium soap of fatty acid having 12 to 24 carbon atoms, said barium soap having a pH value at least as low as 7.0 and being prepared by dissolving said fatty acid in said mineral oil, adding an aqueous-oil slurry of carbonate-free barium hydroxide in not more than stoichiometrical proportions, based on the fatty acid, and heating the ingredients to a temperature of about 200 F. to form barium soap in situ.

2. A reversible anhydrou lubricating grease composition consisting essentially of a mineral base lubricating oil thickened to a smooth homogeneous solid grease consistency by 10 to 35% by weight, based on the total composition,

"- of barium soap of aliphatic fatty acid having between about 12 and about 24 carbon atoms, said soap havin a pH value at least as low as 7.0, said soap being prepared by dissolving said fatty acid in said oil, adding not more than a theoretical quantity of a carbonate-free barium hydroxide in an aqueous-oil slurry to saponify said acid, heating the ingredients to a temperature of. about.200 F. to form the soap in situ, and thereafter heating to a temperature Within therange of about 275 to 425 F. to remove water and leave a smooth grease structure.

3, A process for making a reversible lubricating grease composition substantially free of soaps other than barium soap which consisting essentially of the steps of dissolving aliphatic fatty material having between 12 and 24 carbon atoms per molecule in mineral lubricating oil, neutralizing said fatty material with not more than a stoichiometrical quantity of freshly hydrated barium oxide which is substantially free of barium carbonate, heating said composition to a temperature between 275 F. and 425 F., and slowly cooling said composition to a soap forming temperature of about 200 F., and thereafter removingwater by heatin further to substantially ambient temperature to obtain a smooth homogeneous solid grease product having a pH value not greater than 7.0.

4. A process for preparing a reversible lubricating grease of barium soap and mineral lubricating 0 oil 'base substantially free of other soaps, which consists essentially of calcining a barium-oxygen compound containing CO2 to substantially remove said CO2 and leave a substantially pure barium oxide, hydrating said oxide in a manner substantially to protect said oxide from contact with CO2, incorporating said hydrate together with at least a theoretical proportion of C12 to C24 fatty acid in -mineral base lubricating oil, heating to an elevated temperature to form a nonbasic substantially pure barium soap in situ in said oil, and slowly cooling the oil and soap mixture thereby forming a stable smooth homogeneous solid grease structure.

5. A process for preparing a smooth solid homogeneous reversible lubricating grease of barium soap and mineral oil base substantially free of other soaps, which consists essentially of the steps of mixing a suflicient quantity of saponifi-' ARNOLD J. MORWAY. JOHN C. ZIMMER.

REFERENGES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,154,383 Ott et al Apr. 11, 1939 2,303,256 Camelford Nov. 24, 1942 2,332,247 Morway et al. Oct. 19, 1943 2,417,433 McLennan Mar. 18, 1947 2,434,539 Beerbower et a1. Jan. 13, 1948 2,450,224 Bergmann et a1. Sept. 28, 1948 OTHER REFERENCES Boner: Metallic Soaps for Thickening Mineral Oils, article in Industrial and Engineering Chemistry, vol. 29, pp. 58, 59, and 60, Jan. 1937.

McLennan: Methods of Compounding Barium Greases, article in National Petroleum News, R-234, R-236, R-238, R-239, April 5, 1944.

Claims (1)

1. AN ANHYDROUS, REVERSIBLE LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF 50 TO 90% BY WEIGHT, BASED ON THE TOTAL COMPOSITION, OF A LOW COLD TEST MINERAL OIL THICKENED TO A SMOOTH HOMOGENEOUS SOLID GREASE STRUCTURE WITH 10 TO 50% OF BARIUM SOAP OF FATTY ACID HAVING 12 TO 24 CARBON ATOMS, SAID BARIUM SOAP HAVING A PH VALUE AT LEAST AS LOW AS 7.0 AND BEING PREPARED BY DISSOLVING SAID FATTY ACID IN SAID MINERAL OIL, ADDING AN AQUEOUS-OIL SLURRY OF CARBONATE-FREE BARIUM HYDROXIDE IN NOT MORE THAN STOICHIOMETRICAL PROPORTIONS, BASED ON THE FATTY ACID, AND HEATING THE INGREDIENTS TO A TEMPERATURE OF ABOUT 200*F. TO FORM BARIUM SOAP IN SITU.