US2600058A

US2600058A - Lubricant containing soap of phosphated hydroxy fatty acid or glyceride

Info

Publication number: US2600058A
Application number: US80574A
Authority: US
Inventors: Edwin C Knowles; Oney P Puryear; George W Eckert
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1949-03-09
Filing date: 1949-03-09
Publication date: 1952-06-10
Anticipated expiration: 1969-06-10

Description

Patented June l0, 1952 UNITED STAT ES m1 ENT' oF-Frca LUBRICANT CONTAINING SOAP [HOS- PHATVED- HYDROXY FATTY ACID 0R.

GLYOERIDE 11Claims. (01252-325) l Thisinvention relatesto a lubrioating composition' and particularly a lubric'a'ting grease-prepared'froma soapof a-phosphated'hydroxy fatty acid or glycerid'e;

Qne ofthe principal objects' of the presen't-invention is to provide alubrica'tin'g composition containing as an additive to improye the-lubricating characteristics thereofa-metal soap of: a phosphated: soap-forming hydroxy'fatty acid or glyceride thereof, such as phosphated castor' oil or 'pho'sphated hydrogenated" caster: oil.

Another object" of the invention is to provide alubr-icating grease-compri'sing-an olea'g'in'ous' liquid lubricatingbase containing; a sufiicient proportion-of asoa'p ofa phosphated hydroxy: fatty acid or glyceride of this charac'ter to thicken the lubricating base to a gel-like-consistencya Other objects and.- advantages: of the invention will be apparent from thefollowing-description andthe accompanying claims.

In accordance with thepresent-invention a novel type of metal-soap of a plibsphated hydro'xy fatty acid" or glyceride isemploy'ed I as an additive to' impart-enhancedlubricating characteristics-pr to thicken the-"mineral lubric'atiIig -oilo": other oleag'inous liquid lubricating baSe 'tUatgel-like consistency to -form a lubricating greas'e; In the preparation of 0 this i additive or soap the yario'us soap -forming *hydrox'y fatty acid glycerides and their corresponding hydroxy fa'ttyacids are first modified by phos'phadsio'n to substitute a pentavalent phosphate groupfor the hydroxy group' o'f the glyceride" or acid with the splitting off"o'f Water. This produces acomplex compound containing both the carboxylic aeid radical (as a glyceride where thestarting material is a glyceride) and the phosphate acid radicals. The-re sulting compound is then reacted with a sufli'cient proportion of a basic metallic'compound, such as an oxide or hydroxide, for neutralizationof the phosphate radical and for saponificatio-n of the glyceride or fatty acid radical.

z. forming fatty material, phosphated: caste il and'phosphated hydrogenated castor oiL-are specifically mentioned. In the following description, phosphated castor oil will lee-specifically discussed by way'of preferred example butdtis to be understood that the .inyentionvapplies in the same manner to the phosphated hydrogenat ed-castor oil and to thephosphat-ed hydroxy fatty acids enumerat'edabove.

Castor: oil contains the-,glyceride of. ricinoleic acid, an unsaturatedhydroxyiCm: acid having the'formula 7 3 onko imoniomion o'mcm) '10 'ofon Phosphated casterv oil. has the phosphate1group linked to the iglyceride 'of tl'lCln01elC &Cid':'by-;1'8- placing the hydroxy; group j in the: .12- position, as follows: t-

, g a: L

' HKC EMEHYOHE.GH;=@fi );,y;,do; A 'phosphated a t r qil product available corn"- memially ives the following tests: c

Neutraliz'a'tionnumber 136 saponification' number 290 150 310 Iodine number 75101280 Phosphorus 1(tota1)',=per cent 3E5 to ="4;6

accepts hydroxy fatty acid glyceride, phosphated castor oil, phosphated hydrogenated castor oil and similar expressions are employed in the following description and claims, it is to be understood that each designates the type of compound described above wherein a pentavalent ortho-phosphate group has been substituted for a hydroxy group attached to the carbon chain remote from the carboxyl group of the hydroxy fatty acid or glyceride thereof, with the splitting off of water. The resulting phosphated compound thus contains the unmodified COOI-I group of the hydroxy fatty acid (or the corresponding glyceride thereof) as well as unneutralized OH radicals of the ortho-phosphate group, with both the COOH group and the OH radicals of the orthophosphate group of the compound being available for neutralization in the formation of the metal soap.

Alkali, alkaline earth, and polyvalent metal soaps of the phosphated hydroxy acids can be employed in accordance with the present invention in relatively small proportions of the order of 0.1-5.0% or greater in a mineral lubricating oil as an additive to impart enhanced lubricating properties. Low concentrations of these soaps in lubricating oil to provide a liquid lubricant impart added body, greater load carrying capacity (extreme pressure properties), and better corrosion and rust resistanc as compared with the base oil. As specific examples, an improved textile lubricant is produced by the addition of about -0.5-2.0% of the sodium soap of phosphated castor oil to a mineral lubricating oil having a SUS. viscosity at 100 F. of about 50-120 to give a heavier bodied oil; and, for protective coatings, the addition of about 1.55.0% of the calcium or other alkaline earth or heavy metal soap of the phosphated castor oil to a similar mineral lubricating oil can be employed to give products having a definite yield point or even a gel-like structure.

Moreover, the metal soaps, particularly those of such elements as sodium, lithium, magnesium, zinc and aluminum and the mixed base soaps, such as sodium-calcium and sodium-lead, have been found to produce lubricating greases having advantageous, and in certain respects, unusual properties when added in suificient proportion to thicken the mineral lubricating oil or other oleaginous liquid lubricating base to a gel-like consistency. Ordinarily, a proportion of soap in excess of about up to about 40-45% by weight on the weight of the grease composition is employed to produce greases meeting the specifications of the different grades. Any of the various mineral lubricating oils customarily employed for grease making, as well as the various types of synthetic liquid oleaginous lubricating bases having comparable viscosities can be employed as part or all of the lubricating bas with these particular soaps. Among the types of synthetic oleaginous liquid lubricating bases which are suitable may be mentioned the oil-soluble high boiling high molecular weight aliphatic ethers, aromatic esters, aliphatic monoand dicarboxylic acid esters, phosphorus acid esters and halogenated aromatic compounds which possess lubricating properties and also have small change in viscosity for a given change in temperature. Of th various synthetic oleaginous compounds specified, those falling within the category of aliphatic dicarboxylic acid esters and particularly the branched chain aliphatic esters, such as di-2-ethylhexyl sebacate, are preferred. In the following description and claims, the expression oleaginous 4 liquid lubricating base is employed to designate both the mineral lubricating oils and the synthetic lubricating bases specified.

In the preparation of a grease in accordance with the present invention, the particular phosphated hydroxy fatty acid or glyceride is heated with a metal oxide or hydroxide in the presence of water and a portion or all of the mineral lubrieating oil or other liquid oleaginous vehicle at a temperature of about 175-240" F. for a period of about 1-2 hours, utilizing suiilcient of the metallic base to effect complete neutralization of the acid groups of both the phosphate radical and the carboxylic acid radical. Following this saponification period the product is then dehydrated by heating at a higher temperature up to about 300- 330 F. for a-further period of about /2-3 hours. Any further oil addition is made to the saponified product during dehydration, or following dehydration and as it gradually cools, with continual stirring to obtain the desired consistency; and additional ingredients or additives, such as antioxidants, anti-corrosives, extreme pressure agents, dyes and the like, can be incorporated. The product is ordinarily drawn after cooling to a temperatur of about 200-l00 F. to provide the ultimate gel-like grease.

Also, in accordance with the present invention, the properties of ,the resulting phosphated hydroxy acid soap greas can be desirably modified by utilizing a mixture of the phosphated hydroxy fatty acid or glyceride with a conventional soapi'orming fatty acid or glyceride for the saponification step. Any of the ordinary saturated and unsaturated soap-forming fatty acids and fate or of the hydroxy fatty acids or hydroxy fats, including the hydrogenated fats and fatty acids, such as hydrogenated fish oil acids, can be employed for this purpose. A mixture consisting essentially of substantial portions each of the phosphated hydroxy fatty acid or glyceride and an unmodified hydroxy fatty acid or glyceride, as well as the foregoing mixture in major proportion together with a minor but modifying proportion of a conventional soap-forming fatty acid, have been found particularly advantageous in accordance with the present invention. In addition to saponifying a mixture of the phosphated hydroxy acid and other carboxylic acid with the desired metal base or mixture of metal bases, satisfactory greases can also be produced by separately preforming the two or more types of soap specified and then mixing them with the addition of further oleaginous liquid lubricating base to produce a grease of the required consistency.

The following examples are set forth as representative and illustrative of the present inven- EXAMPLE I A sodium base grease of phosphated castor oil was prepared as follows: 200 grams of water, 3'75 grams of a naphthene base lubricating oil having an SUS. viscosity at F. of 307, and 370 grams of the abov mentioned commercial phosphated castor oil containing 3.7 by weight of combined phosphorus and having a neutralization number of 156, a sapcnification number of 295 and an iodine number of '79, were charged to a grease kettle, and heating and stirring were initiated. When a temperature of the kettle contents of 200 F. had been reached, 157 grams of a 50% aqueous solution of sodium hydroxide was added dropwise over a period of /2 hour, and an additional 100 grams of rinse water was added in a further period of 5 minutes. The saponiiication reaction gaseous was continuedat"2 '-206 F.- for a furtherperiod of 1 hour? 'Ihe tempe'rature was then gradually raised to 300 Rover aperiod of hour, and a further quantity of 1900 grams of the said naphthene base lubricating" oil was introduced slowly.

grease to texture change when worked undershearing stress, the test being carried out a scribed in U. S. Patent No. 2,450,219, Ashburn and Puryear, in column 5, lines 6-19. A small change in miniature penetration of the sampleafter' test Then heating-and stirring at about 300-309 F. in comparison with the original is indicative nf for 'dehyclration with continued oil addition was excellent texture stability under highshearing carried out over a period of about 4 hours, when a stress. The miniature penetration test is'dec ontrol sample taken for-penetration showed an scribed in Ind. Eng. Chem., Analytical-Edition. ASTM iuiworked. penetration of 123 at '77" F. and 10 vol. II, page 108, February 15, 1939. a worked penetration of 210 at 80 F. The heat The grease breakdown machine-testis used -to was then cut and the temparature dropped slowly determine-the lubricating'properties of'b'all bearwith continued stirring to about'210? F. over a ing greases at various temperatures. "The inaperiod of 1% hours. A solution of 13.5 grams of chine employed consists essentially of a'standdiphenylamine in 50 grams of the naphthene ard motor-driven rotating ball be'aringQQ-ir'im. base lubricating oil, together with V 500 grams borer: 47 mm. diameter x 14 mm. widthymountadditional or the lubricating oil were then-slowly ed vertically andenclosed in an oil jacketje'onadded atthis temperature over a period of'-% taining an electric immersion coil with adjiist- "hour. The resulting procluct-wasthen' drawn to able rheostat f0r temperaturecontrol. Thef upobtain anexcellent yield of a transparent light per face of the bearing is not covered, so -that yellow stiff buttery'grease. observations of performance during operation A'series of other metal soap greases of the comcan be made. The bearing is charged withfi 'mercial phosphated castor oil, including alithium grams of the grease initially. With the system base grease, a magnesium base grease, a zinc at atmospheric temperature, rotationof {the base grease, an aluminum base grease, a 3:1 5 packed test bearing is'started at 3450 R. P.-"M. sodium-calcium mixed base grease and a 3:1 and allowed to proceed for 3 minutes, during sodium-lead mixed base grease were also prewhich time observations are taken of the general "pared in a similar manner and "utilizing the same nature of lubrication provided, i. e., whether or naphthene base lubricating oil. Typical tests not the grease folds over the bearing, channels, *a'nd the characteristic appearance of the above slings away from the bearing, tends to b a1l up,'" described sodium base and the other'metal base etc."-Then heat is applied tothe bearing'asqit "greases so obtained are set'forthin-the following continues to rotate at the same speedso as to Table I: gradually raise the temperature of the-bearing Table I Soap, AS/TM a vMetal are are tat-d lated nworked sodium 5 185 .144 293 transparent namilow, stifi, buttery. lithium 12.6 500+ 138 '269 clear amber, light .feather. magnesium 20 340 275 344 transparent amber, U "stringy. zinc 20 233 201 274 opaque ivory, soft,

buttery. 'alumimum. 23.8 224 191 -24!) amber, transparent gel. sodium-calcium. 10 407 128 273 transparent'pale yellow, hard, buttery. sodium-lead.-. 15 268 157 286 tan,stifl, buttery;

In addition to the foregoing tests for dropping 50 until the grease fails to lubricate (the breakdown point and penetration, other tests were obtained onthis series of greases asset forth in appended Table II:

Table II Na Li Mg Zn NazCa 'Na:Pb

Dyn'emieShear Test, r iature Penetration: I

Original 41 45 4O 83 Final 34 113 35 -36 Lubrication-Grease Break- "down Machine-R. T. to v 300 -I; A E E E E -E Lo ;TemperatureTorque. seal/rev;

Minus 20 F 18- 11.8 l9: 6 Minus 30F. -67 -87 =6 2 .5 04.3 "Liibrfcation lorque Break- "down Machine:

Timken Bearing 80 .F F E E E E It Timk'en Bearing 80250 V F G E E P E E Federal Bearing 80 F. G E G G E E "FederallBcaring80-250' F G E P G G The dynamicshear resistancetest oi the forepoint) or until a temperature of 300"F. :is

reached in about 40minutes from the start of the test; Beginning at a bearing temperature 'of100 F., observations of performance are'recordedaior every 25 F. temperature rise or for any significant development such as 1 texture change, expansion in volume, air'entrainment, channeling, leakage,

melting and consequent thinning, separation, 'discoloration, vaporization, etc. After completing the run, the bearing is' removed and cooled;- and grease'remainingon the bearing is examined for texture and consistency change, discoloration,

etc. and compared with" the original g'rease. The

i1 results obtainedare compared 'with those-secured in'the same test'on a -standardpremium balhand roller bearing grease of known excellent periormance; and the performanceoi the test-grease is rated on a comparative basis as E for excellent, G for good, A'foradequate, F for fairand'r-P for poor. I

The low temperature torque test 'of the: foregoing table is essentially a measure of the resistance of the greaseto cori'gealing 'anda'ofiits 'abilityto aiford proper-lubrication under ae'xtremelylowtemperature cond'itions' such-"as are fixed outer race.

. The apparatus employed for the test consists essentially of a vertically mounted hollow spindle with a No. 204K Conrad type S-ball bearing mounted on the bottom, and a drum on which is wrapped a coiled line for applying torque mounted on the top. The bearing packed with a 60% capacity charge of the grease to be tested is clamped at the inner race to the spindle, while the outer race is clamped immovably to a stationary cup within which the bearing is inserted. The assembly is inserted with the lower bearing end in a low temperature bath containing isopropyl alcohol, and the desired temperature of the bath and bearing is attained by dropping 1 Dry Ice in the bath. The drum and drum extension carried at the upper end of the hollow spindle and protruding from the bath are held in vertical position by a tapered roller bearing. The line coiled around the drum extends over a pulley to hours is utilized to cool the bearing to the test temperature, and an additional soaking period at the test temperature is permitted such that the test is not run until three hours from the start of cooling. When the desired bearing temperature and soaking period are attained, a 2000 gram-centimeter torque load is applied in both clockwise and counterclockwise directions, and the number of seconds for one rotation in each direction is observed and the readings averaged.

The torque breakdown machine test is designed to evaluate the lubricating properties of greases used for the lubrication of anti-friction bearings. Two standard 3.9370 inch Timken tapered roller bearings packed with about g. each of the grease under test, and a standard Federal Precision Ball Bearing No. 1211 packed with about 32 g. of the grease are employed, the packed bearings being weighed before test. In the test -i of each bearing, the bearing is assembled on a motor driven shaft supported by pillow blocks within a bearing housing mounted within an insulated chamber, with a system of levers connected to register any movement of the bearing .3;

housing in grams on a platform scale, whereby both the starting torque and the running torque can be measured. The insulated chamber is equipped with a copper coil tubing for the circulation of a cooling or heating medium, and

also with an insulated cover equipped with an electric heater and a motor driven fan, whereby the temperature of the chamber and bearing under test can be accurately controlled. The test of the Timken bearings at 80 F. is made at 900 R. P. M., and the test of the Federal bearing at 80 F. ismade at 1750 R. P. M., each for a period of two hours. The instant the motor driving the test bearing is started, the first torque reading is recorded as the starting torque. Then running torque and temperature readings of the hearing are recorded at one minute intervals for the first minutes, and at 10 minute intervals for the remaining 1 /2 hours, while the temperature within the chamber is adjusted to maintain the bearing temperature within 2 of 80 F. At the end of the run, the bearing is removed from the housing and weighed, whereby the weight of the grease remaining on the bearing can be computed. The weight of the grease on the housing A time of not less than two is also determined; and grease leakage (grease escaping from both the bearing and housing) is determined by actual weight measurement or by difference. A visual inspection is made of the grease remaining on the bearing to ascertain whether any structure or texture change has taken place; and the penetration of a sample of the grease taken from the bearing after test is compared with the original penetration of the grease. A second test procedure is conducted on the same machine in this manner, except that in this case the temperature of the chamber and of the bearing is raised gradually from an initial 80 F. to a temperature of 250 F. at the end of an hour. The test is then run at 250 F. for an additional two hours before terminating the test. Similar readings are made as previously described. The results thus obtained are compared with those secured in the same tests on a standard premium ball and roller bearing grease of known excellent performance; and overall lubricating performance of the test grease is generally reported on the basis of this comparison as E for excellent, G for good, F for fair and P for poor.

The foregoing Tables I and 11 show that the phosphated castor oil soap greases of the present invention show advantageous and, in certain respects, unusual properties. The sodium, lithium and sodium-calcium greases have high dropping points, with the lithium base grease having the unusual dropping oint above 500 F. Most of the greases tested by the dynamic shear test show excellent to fair resistance to working down; and practically all of the greases showed excellent performance in the rigorous grease breakdown and torque breakdown machine tests. A sample of the 3:1 sodium-calcium grease containing 0.5% by weight of diphenylamine gave adequate lubrication in a 168 hour continuous run at 228 F. in the torque breakdown machine using a Federal ball bearing. In addition to the tests listed, tests were made on the Timkin E. P. Machine on the sodium base grease with various loads ranging from 10 to pounds OK being obtained, which indicates that the phosphated castor oil soap greases possess extreme pressure characteristics.

EXAMPLE II The following example is listed as representative of a lithium base grease of phosphated castor oil possessing excellent low temperature and lubricating properties which adapt it for specialized ball and roller bearing uses. 100 grams of water, 375 grams of an acid-treated light pressed distillate paraffin base lubricating oil having an SUS viscosity at 100 F. of 101, and 370 grams of the above mentioned commercial phosphated castor oil having a phosphorus content of 4,54%

by weight, a neutralization number of 146, a

saponification number of 301, and an iodine number of were charged to the grease kettle and heating and stirring started. When the temperature of the kettle contents reached 196 F., 470 grams of a 10.1% aqueous lithium hydroxide solution were slowly added over a period of hour and an additional 50 grams of rinse water then introduced. iSaponification proceeded for 1 hour at 200-202" F., when the temperature was raised to about 300 F. for dehydration. With the temperature maintained at 301-304" F. over a period of about 2 hours, 1700 grams of ell-2- ethylhexyl sebacate having an SUS viscosity at F. of 68 and a pour point below 80 F. were gradually added to bring. the grease to debaselubricating oilin the final product. The heat was then cut and the product gradually cooled with continued stirring, during which time 13'grams of phenyl alpha-naphthylamine in 50 gramsof the parafiin base .oil and 0.1 gram of, a suitable dye were added. The resulting product was drawn at 225'F.. to obtain a hard; gel-like orange-colored grease having the following calculated composition:

Per cent byweight th ml p f h spbat dc stere l "tie-.3.

..-T--.-re-Prz: r-srfire-rf- Parafiinb e z u iea neo l 4-8 .-.2:ethr h x ;sebeeate -4 1 benyla ph n ht y min Dye; 0.002

Low temperature torque-minus 97 F.,

s'ec /rv. 11.1 Oil separation test SO' hr. at 212 'F.:

Separatiom per cent' 5.2 Evaporation; per cent 0.18 T l. separ i te t s e ri ed nArmv- Navy Aeronautical Specification AN+G3G, Low em e u r atine G a pag 5, M rch 6, 1943, This is a measure of the resistance of the grease to oil bleeding and'evaporation, In this test grams of the greaseare placed in a weighed 60 mesh screen cone supported from the rim of aweighedlQO milliliter beaker so that the pointed bottom of the screen cone containing the rease is substantially above the bottom of the ker- Th as m isthe pla e n a r v y convection oven maintained. at 212 F. for a p rio oifio 119 15. t the endi f t period, t e assembly is removed, cooledin a desiccator, and the b aker an c ne w ehe it e t andthe' a er. hed s p r telr: h a We t the beaker minus theinitial' weight of the beaker divided by the initial weight of the grease sample times 100 is reportedasper cent bleeding. The

n a weieht he eaker l s ,eene. a ase.

m nust final we e te-fp h e ke l mine.

nd. r a e i e b ein ti W t O the.

grease sample'timeslOOis reported as per cent Th cr ee ne st ncl n t e e eep q e ly h dr p int a ove. 500 F5, t a i ieer r r e 1the xc t ow, t p rat re t ue;-

(operable at 497 F. and probably at lower temperatures); the-low oil separation and evaporation at 212 F for a light oil as employed,,and the excellent lubricating properties for ball and roller-bearingsover wide ranges of temperature show that this .is a premium type ofgrease of unusual character.

tioned commercial phosphated castor oil with aa.

minor proportion of a conventional, fatty acid,',, such as stearic acid, particularly for the production of a-grease having exceptional low. tempera-. ture properties in addition to providing excel-H lent lubrication overa wide temperaturerange.

324 grams of phosphated castor oil of the char-L acter specified above; grams of triple pressed" stearicacid, 310 grams of anacid-treatedlight pressed distillate parafiin base lubricating oil have ing an SUSviscosity at 100 F. of 101, 200 grams: of water, and 513 grams of a 10.1%. aqueous, lithiumhydroxide-solution Were charged. to at greasekettle and'heating and stirring-started".- Saponification was effected at a temperatureiof -190 F. over a period of 2 hours. Thenthe temperature wasraisedrapidly to above 300 F. and maintainedxat-about BIL-324 F. for 2hours to eifect dehydration. 930 grams of di-2-ethyl-e hexyl sebacate were-then added slowly over a; period of-4 hours with continued stirring as-the... temperature dropped to about 220 F. with 6.6" grams of phenylalphanaphthylamine included in the final portion of the added di-2-ethylhexyt' sebacate. During continued stirringand. asthe temperature dropped to'about 180 F., 100 grams of a blend-of the di-Z-ethylhexyl sebacate witlr theparafiin base oil in the ratio-of 3:1 and'con-i taining 0.5 grams of phenylalphanaphthylamine'a were added, followed by an additional 50 grams; of the 3:1 blend containing 0.25 grams of phenyl'e alph'anaphthyla'mine. The grease was drawn .at a temperature of 1'74 F. and a final product of a"- brown smooth. glossy buttery medium feather" greaseobtained, having the following calculated;- composition:

Per cent by weight" Lithium soap of phosphated castoroil 17:3". Lithium stearate 6.0: Di-2-ethylhexy1 sebacate 56.0 Paraffin base lubricating oil 18.6 Glycerine 1.5 Phenylalphanaphthylamine 0.5 Excess LiOI-I 0.1

Dropping P0in't,-'F.-. Penetration AS'IM, 77 F.:

Unworked .\Vorke'(1 Free Alkali (LiOH), per cent. Free fatty acid (01eic), per cent Oil.separation30 hrsl-at 212 F., per cent. Moisture Test l0 sec. immersion Oxidatio11Norma-Hofim ann Bomb:

(a) 110 5.1., 210713, 400 hrs, lbs.- 5max 3.-

drop per 100 hrs. (0) copper catalyzed, 110 p. s. i.; 210 I F:, 20'hoursl -4.-- passes'.- Low Temperature torque.v67 F., 2000 g. cm;, 3 g. of grease, sec/rev 117. Working Stability (100,000 strokes):

Penetration, ASTM,.77 F. 0 inal '(unworked) 198: Final r 267.; Dynamic Water Resistance Loss, per cent.

1 Noclouding or emulsificaticn. 9 No change ingrease or stain on copper. I

The moisturetest as set forth in; the foregoing; 2434 Specification is 'made by taking to gram of the grease on the end of a stirring rod and immersing for 10 seconds in water in a 200 milliliter beaker. During the period of immersion, the water is observed visually to detect any appearance of cloudiness or other evidence of emulsification of the grease.

The Norma-Hofimann oxidation test is a measure of the resistance to oxidation of lubricating greases when stored under static condition for long periods of time, as when coated in thin films on anti-friction bearings, motor parts, etc. In this test, five four-gram samples of the grease are put in flat sample dishes and placed in a stainless steel bomb sealed with a lead gasket in an atmosphere of oxygen under an initial pressure of 110 pounds per square inch at a temperature of 210 F. The pressure drop in pounds within the bomb is then recorded at intervals of 100 hours up to 400 hours or until a pressure drop of 55 pounds per square inch occurs.

The copper catalyzed test of the foregoing table is conducted in the same apparatus, except that a strip of copper is partially immersed in the grease sample. At the end of 20 hours at 210 F. the grease is examined for decomposition or any change in color or consistency, and the copper strip is examined for evidence of corrosion or stain.

The Working Stability test is described in the Army-Navy Aeronautical Specification AN-G-25 for Low Temperature Aircraft Lubricating Grease, October 9, 1947, and is a measure of the texture stability of the grease under shearing stress. In this test a mechanical worker consisting of a cylinder filled with the grease sample to be tested and containing a plunger plate having approximately 270 holes of 5 inch diameter each is employed, and the plunger is worked back and forth through the grease at the rate of 60 double strokes per minute until 100,000 double strokes have been completed. The final penetration of the worked grease is then taken and compared with the original unworked sample.

The dynamic water resistance test of the foregoing table is that described in Army-Navy Aeronautical Specification AN-G-25, Low Temperature Aircraft Lubricating Grease, Item F-df, October 9, 1947. This measures the resistance of the grease against being washed out of the beaning in the presence of water. Briefly, the test involves the 204K Conrad ball bearing mentioned above pack with 4 grams of the grease and clamped in a tight fitting housing which allows th inner race to rotate. The latter is mounted on a horizontal shaft and rotated at 600 R. P. M. while a fine stream of distilled water is directed against the end plate of the bearing housing just above the outer opening of the bearing housing. This operation is continued for one hour, when the loss in weight of the dried bearing is then reported as grease loss; and this loss in weight divided by the weight of the grease used in packing the bearing is reported as the percent loss.

The tests of the foregoing table show that this grease easily passes the difficult requirements of the 2-134 Specification. In addition, the high dropping point, the very low tim required for one revolution at 67 F. in the low temperature torque test, and the excellent working stability and water resistance of this grease make it outstanding.

Another batch of this lithium base grease of the same formulation was tested in comparison with a conventional lithium base low temperature grease prepared from hydrogenated castor oil and now on the market, with the results shown in The mean Hertz load test is mad with the so-called four-ball EP machine as described in the U. S. Naval Engineering Experiment Station Report on Cooperative Evaluation of EP Lubricants, May 3, 1946. This machine comprises essentially a ball pot in which three inch diameter bearing balls SKF Grade 1, are locked in place by a lock ring and nut. A vertical driving shaft terminating in a ball chuck holder, into which is inserted a ball chuck containing a fourth bearing ball of the same type, extends downwardly into the ball pot so that the fourth ball rotates as it is pressed against the three stationary balls. The ball pot is attached to a mounting disc supported on a thrust bearing, so that the ball pot assembly is free to rotate about its vertical axis; and the ball pot assembly is forced upwardly to engage the balls at predetermined pressures by means of weights applied to a counterweighted lever arm acting through a pressure pin, step bearing and cross-head, the latter supporting the said thrust bearing. In each run, the balls are coated with the greas under test; and the vertical shaft is driven at 1800 R. P. M. for 10 seconds at an applied load. The three balls in the ball pot assembly are thenremoved for measurement of the scars formed by rubbing of the top or fourth ball on the three lower balls. A new set of four balls is used for each run. This is a measure of the extreme pressure properties of the grease and the empirical figures of the table set forth the so-called extreme pressure value, termed the mean Hertz load, which latter is based on a relationship between the wear-load diagram obtained with the lubricant tested and that of a theoretically perfect lubricant, as described by the so-called Hertz line of elastic deformation. Each determination requires 20 to 27 ten-second runs at prescribed increasing loads up to welding, with subsequent measurement of wear-spot diameters formed on the test balls. The division of a factor, supplied for each applied load, by the wear-spot diameter is made; and the results are averaged to yield a numerical evaluation of the extreme pressure properties of the grease. A higher numerical value represents a closer approach to the theoretically perfect lubricant.

The salt spray test is designed to evaluate the ability of a coating of the grease to protect metal specimens, such as boiler steel specimens, against corrosion in the presence of salt or sea water spray. In this test the metal specimens coated with the protective layer of the grease under test are supported at a angle in an enclosed salt spray box held in an inclined position. An atomizer consisting of two nozzles arranged at right angles is mounted in the lower portion of the inclined box, one nozzle being connected to a source of clean compressed and water-saturated air under a pressure of 12-15 pounds Per square inch, with the other nozzle opening into the bottom of the box to draw salt solution up through this nozzle, atomizing it in the form of a very fine mist. An inclined baille is mounted between the atomizer and the specimens under test to keep the spray from impinging directly on the specimens. A synthetic sea water solution is used as the salt spray, this synthetic sea water solution being prepared as follows. A stock solution containing 10 grams of KCl, 45 grams of KBr, 550 grams of MgC12.6H2O and 110 grams of CaClz.6HzO with sufiicient distilled water to make 1 liter, is prepared. Twenty milliliters of this stock solution is then mixed with 23 grams of NaCl and 8 grams of NazSO4.lH2O, and with suflicient distilled water to make up to 1 liter. As shown by the table, the operation is continued for 100 hours at 95 F., and then the specimens are removed and the percentage area of the specimens coated by rust is determined.

As shown by the foregoing Table V, this lithium base grease of the present invention has a higher dropping point, higher load carrying capacity (mean Hertz load), greater resistance to salt spray, and better copper corrosion protection than the premium type of lithium base low temperature grease now employed.

While the foregoing examples illustrate preferred types of greases prepared from the commercial phosphated castor oil, which consists roughly of about equal proportions of phosphated castor oil with unmodified castor oil, it is to be understood that advantageous types of greases as well as improved liquid lubricants can be prepared from phosphated castor oil alone, or phosphated hydrogenated castor oil alone, or mixtures thereof. Likewise, the various other mentioned phosphated soap-forming hydroxy fatty acids or their glycerides can be used in a similar manner. In order to obtain the advantages of the phosphated type of soap in the preparation of lubricants or greases of the present invention, it is desirable to employ as the soap-forming carboxylic acid or glyceride constituents a mixture containing at least about 25% by weight of the phosphated hydroxy fatty acid or glyceride, with the balance being composed of unmodified hydroxy fatty acid or glyceride, or conventional soap-forming fatty acid or glyceride, or mixtures thereof.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as ar indicated in the appended claims.

We claim:

1. A lubricating grease comprising an oleaginous liquid lubricating base containing in excess of 5% and up to 45% by weight based on the grease of a metal soap of a phosphated soapforming material selected from the group consisting of a phosphated soap-forming hydroxy fatty acid and a phosphated soap-forming hydroxy fatty acid glyceride sufficient to thicken said lubricating base to a gel-like consistency.

2. A lubricating grease comprising an oleaginous liquid lubricating base thickened to a gellike consistency with a proportion in excess of 5% and up to 45% by weight based on the grease of a metal soap of phosphated castor oil having the formula 0 o ornwrnm in.oH,-oH=oH oH2 1 -orr where M is an alkali metal. 132..-

3. A lubricating grease according to claim 2, wherein the oleaginous liquid lubricating base consists of a major proportion of an oil-soluble high molecular weight high boiling liquid aliphatic dicarboxylic acid ester within the lubricating oil viscosity range and possessing lubricating properties and a minor proportion of a mineral lubricating oil, and M of the metal soap is lithium.

4. A lubricating grease according to claim 3, wherein the said aliphatic dicarboxylic acid ester is di-2-ethylhexyl sebacate.

5. A lubricating grease comprising an oleaginous liquid lubricating base thickened to a gellike consistency with a proportion in excess of 5% and up to 45% by weight based on the grease of lithium soap consisting of a major proportion of the lithium soap of phosphated castor oil and a minor proportion of lithium soap of a saturated soap-forming fatty acid.

6. A lubricating grease according to claim 5, wherein the lithium soap of the saturated soapforming fatty acid is lithium stearate.

7. A lubricating grease comprising an oleaginous liquid lubricating base thickened to a gellike consistency with a proportion in excess of 5% and up to 45% by weight based on the grease a sodium soap of phosphated castor oil.

8. A lubricating grease comprising an oleaginous liquid lubricating base thickened to a gellike consistency with a proportion in excess of 5% and up to 45% by weight based on the grease a mixed base sodium-calcium soap of phosphated castor oil.

9. A lubricating grease comprising an oleaginous liquid lubricating base containing in excess of 5% and up to 4. 5% by weight based on the grease of a metal sOap of a phosphated hydrogenated castor oil sumcient to thicken said lubricating base to a gel-like consistency.

10. A lubricating grease comprising an oleaginous liquid lubricating base as the major constituent and a proportion in excess of 5% and up to 45% by weight based on the grease of metal soaps of a mixture consisting essentially of phosphated castor oil and castor oil to thicken said lubricating base to a gel-like consistency, said phosphated castor oil constituting at least 2 5% by weight of said mixture.

11. A lubricating grease according to claim 10, wherein said mixture consists essentially of about 45-50% by weight of phosphated castor oil and 55-50% by weight of castor oil, and the metal of said soaps is lithium.

EDWIN C. KNOWLES. ONEY P. PURYEAR. GEORGE W. ECKERT.

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

UNITED STATES PATENTS Number Name Date 2,128,946 Katzman Sept. 6, 1938 2,142,998 Chittick Jan. 10, 1939 2,228,658 Farrington et al Jan. 14, 1941 2,294,817 Van Dijck Sept. 1, 1942 2,345,734 Dickey et al Apr. 4, 1944 2,356,754 Farrington et a1. Aug. 29, 1944 2,450,222 Ashburn et a1 Sept. 28, 1948 2,450,254 Puryear et al Sept. 28, 1948 2,450,255 Puryear et al Sept. 28, 1948 FOREIGN PATENTS Number Country Date 424,380 Great Britain Feb. 20, 1935