US2755256A

US2755256A - Wide temperature range alkali metal grease containing excess alkali metal hydroxide

Info

Publication number: US2755256A
Application number: US223430A
Authority: US
Inventors: John P Dilworth; Oney P Puryear
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1951-04-27
Filing date: 1951-04-27
Publication date: 1956-07-17
Anticipated expiration: 1973-07-17

Description

United States Patent WIDE TEMPERATURE RANGE ALKALI METAL GREASE CONTAINING EXCESS ALKALI METAL HYDROXIDE John P. Dilworth and Oney P. Puryear, Fishkill, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application April 27, 1951, Serial No. 223,430

18 Claims. 01. 252-333 I This invention relates to ball and roller bearing greases which are characterized by high dropping points and outstanding performance over a wide temperature range. The novel alkali metal greases of this invention are suitable for operation at temperatures as low as 20 F. and as high as 500 F. and upwards.

The novel wide temperature range greases of this in vention result from elevated temperature digestion of a mixture comprising mineral oil, alkali metal soaps of a fatty material of prescribed composition, and a critical amount of excess alkali metal hydroxide. The crtical factors in the production of the wide temperature range greases of this invention are the critical quantity of excess alkali metal hydroxide present during the high temperature digestion, the composition of the fatty material from which the alkali metal soaps are formed, the temperature and duration of the digestion.

The novel wide temperature range greaeses of this invention are prepared by digesting at a temperature of 480 to 550 F. for a period of 2 to 5 hours a dehydrated reaction mixture comprising 15 to 25 per cent alkali metal soaps of a fatty material having an iodine number of at least 90, 60 to 80 per cent mineral oil and 1.3 to 2.3 per cent alkali metal hydroxide. After digestion at the prescribed temperature, the grease is stirred down to a temperature of about 200 F. at which temperature it is drawn. Additives comprising 1 to per cent of the total grease composition may be added during the cooling of the grease after the elevated temperature diges-v tion. Additives comprising 1 to 10 per cent of the total grease composition may be added during the cooling of the grease after the elevated temperature digestion.

The alkali metal greases produced in this invention are characterized by dropping points over 500 F. and possess good low temperature torque properties so that they are properly classified as wide temperature range ball and roller bearing greases. The low temperature properties of the grease produced in accordance with this invention can be improved by milling. An improvement of 10 F. in the low temperature properties results from milling the drawn grease.

Accordingly, it is recommended that the greases of this invention be milled if they are to be utilized in lubricacomposition prescribed in this invention are buttery-type greases with dropping points over 500 F. The preparation of alkali metal greases characterized by the aforesaid properties represents a significant advance in the art of grease making.

Patented July 17, 1956 "ice , the added petroleum mahogany sulfonate salt amounts to about 0.25 to 4 per cent of the final calculated grease composition. The sodium petroleum mahogany sulfomate is added to the reaction mixture together with the parafiin base oil and is present during saponification and dehydration of the reaction mixture. When naphthene base oils, commonly known as pale oils, are employed,

it is not necessary to employ stabilizing agents such as petroleum mahogany sulfonate salts since greases of high stability are prepared without the use of a stabilizing 7 agent.

The mineral oil content of the novel greases of this invention comprise 60 to per cent of the total calculated grease composition. Advantageously, the mineral oil content comprises approximately 65 to 75 per cent of the total grease composition.

Soap-forming materials possessing a substantial olefin content are required for the formation of the alkali metal greases of this invention. The soap-forming stock, which can be soap-forming fatty acids, fatty esters .or mixtures thereof, should possess an iodine number of at least and preferably between 90 and 130.

A particularly preferred soap-forming material comprises a mixture of menhaden oil and hydrogenated fish oil fatty acids, which latter are commercially known as Snodotte acids. A 3 to 1 menhaden oil-Snodotte acid mixture having an iodine value of approximately has proven particularly useful as a soap-forming stock.

Commercially available Snodotte acids have approximately the following soap composition:

. Other unsaturated soap-forming acids and esters having an iodine number higher than 90, such as castor oil, linoleic and linolenic acids, may also be useful in the preparation of greases of this invention.

The soap-forming material of this invention is employed in such amounts that the alkali metal soap content of the final grease composition comprises approximately 15 to 25 per cent of the total grease composition. Ordinarily the soap content of the grease is within the range of 18 to 22 per cent.

As indicated previously, the concentration of excess alkali metal hydroxide present during the elevated temperature digestion is critical and lies in a very small range. It is necessary to maintain concentration of excess alkali between the ranges of 1.3 and 2.3 per cent of the final calculated composition of the grease in order to produce a high dropping point grease. If the excess alkali metal hydroxide concentration is below or above the prescribed range, there is a significant lowering of the dropping point of the product grease.

It has been discovered that the viscosity of the paraf finic mineral oil determines what is the optimum amount of excess alkali metal hydroxide to be used. When more viscous parafiinic mineral oils, for example, SAE grade 30 or 40, are employed in formulating the. grease, best results from the viewpoint of dropping point are obtained if the excess alkali metal hydroxide concentration is in the range of 1.4 to 1.6 weight per cent whereas with less viscous paratfinic mineral oils, such as SAE grade 10 to 20 oils, optimum results from the viewpoint of product quality are obtained if the excess alkali metal hydroxide concentration is in the range of 1.7 to 2.1 weight per cent. However, regardless of the viscosity of the paraffinic mineral oil employed, the. total amount of excess alkali metal hydroxide falls within the prescribed range of 1.3 to 2.3 weight per cent of the final calculated grease composition.

The excess alkali. metal hydroxide may be added either in its entirety prior to elevated temperature digestion of the grease mixture or in two. separate fractions, with the major fraction being introduced prior to digestion. and a minor fraction being added during the stirred cooling of the grease. The entire excess alkali metal hydroxide or the major fraction thereof is added to the grease. mixture together with the stoichiometric quantity of alkali required to saponify the soap-forming. material. The split feed incorporation of the excess alkali metal hydroxide is the preferred procedure and' produces a grease having. superior high temperature properties. 'In the split feed addition.

of excess alkali, approximately 60 to 80 per cent of the total excess alkali metal hydroxide is added together with stoichiometric quantity of alkali required for neutralization of the soap-forming material; the remaining 20 to 40 per cent of total excess alkali is added during the stirred cooling of the grease at. a temperature of about 300 F. A saturated aqueous solution. of alkali metal hydroxide serves as the means of introducing the excess alkali and the stoichiometric alkali required for saponification of the soap-forming material.

The novel greases of this invention may be prepared from all alkali metal hydroxides and the resulting greases are characterized by wide temperature range properties. Sodium and lithium base greases possess exceptionally high dropping. points and good low temperature torque properties.

The temperature and duration of the digestion of the mineral oil, alkali. metal soaps and excesscaustic are also decisive in determining the quality ofthe grease. digestion must be effected at temperatures between. 480

and 550 F. to produce greases characterized by dropping points over 500 F. and good low temperature torque properties. A temperature between 500 and 550 F. is particularly preferred for the digestion. periodof 2 /2 to 5 hoursis prescribed-but digestion times of 3 to.4. hours have proven particularly advantageous.

After. the elevated temperature digestion, the grease is cooledwith stirringto a. temperature of about 200 F. at which temperature it is drawn. Itis important to stir the grease duriugthev cooling period to prevent it from becoming stiff during a phase change which occurs at about 350 F. It has been discovered that cooling the grease kettle at a rate of 50 to 60 F. per hour while the grease Various additives are blended into the. grease after the elevated temperature digestion. of the saponified. dehy- Thc A digestion r' drated mixture. For example, diphenylamine, an oxidation inhibitor, may be blended into the grease at a temperature of about 220 to 250 F. during the stirred cooling of the grease. Aluminum stearate, which imparts water resistance, is added at about 500 F. or at the end of elevated temperature digestion. Ordinarily the final grease composition contains 0.5 to 3 weight per cent diphenylamine and 3 to 7' weight per cent aluminum stearate.

The saponification procedure employed in manufacturing the greases of this invention is effected at conventional conditions. The mineral lubricating oil fraction and the soap-forming stock are heated with stirring to a temperature of approximately to 160 F. to effect good distribution of the reagents. If a paratfin base mineral oil is employed, the stabilizing petroleum mahogany sulfonate salt is added to the mixture at this time. At approximately F. all or a major portion of aqueous solution of alkali metal hydroxide is added to the reaction mixture. In small scale preparations, a small amount of silicone-anti-foam agent may be added together with the caustic solution to minimize foaming. The

saponification is effected at a temperature between. 150

and200 F. in a period of about one hour.

Dehydration of the saponified reaction mixture is effected at a temperature between about 290 and 350 F..

and ordinarily takes approximately 1 to 2 hours. The preferred temperature range for dehydrating the saponified reaction mass is 300 to 330 F.

The. manufacture of the novel greases of this invention is illustrated in,Examples 1 and 2; in Example 1 the grease is prepared with SAE grade 30 paratfinic lubricating oil and the total excess alkali metal hydroxide content, about 1.5 per cent, is incorporated in the grease mixture together with the stoichiometric quantity of alkali required for saponification; in Example ll, an SAE grade 20 paraffinic oil is employed and the excess alkali metal hydroxide, which is about 1.9 per cent, is added in two increments, the major portion being added with stoichiometric amount of alkali and the minor portion during the stirred cooling of the grease.

Example I A mixture of 18 lbs. of SAE grade 30 paratfinic mineral lubricating oil. fraction, 1.8 lbs. of pale oil solution containing 30.5 weight per cent sodium petroleum mahogany sulfonate, 11.6 lbs. of a 3:1 mixture of menhaden oil- S'nodotte acids were charged to a fire-heated kettle wherein they were heated to about a temperature of 150 F. and 6 grams of methyl silicone (Dow Corning Antifoam A) were added; At 150" F. 5.45 lbs. of. a 49.5 per cent solution of sodium hydroxide, and 7 lbs. of water were added to the reaction mixture. The added caustic comprises the stoichiometric amount required to saponify the soapforming constituents and in addition 1.5 per cent excess sodium hydroxide. to' 450 F. over a two-hour period with the resulting saponification and dehydration of. the mixture; at this.

temperature, 2116 lbs. of SAE grade 30 paratfinic lube oil were added over a /2 hour period. The mixture was then raised to 550 F. in a 1% hour period and held at this temperature for approximately three hours. The reaction mixture. was then cooled with stirring to a tcmperature of 500 F. during a period of about 1 hour whereupon 3.0 lbs. of aluminum stearate was then added over a /2 hour period. The reaction mixture was then stirred down to a temperature of 250 F. over a 2 /2 hour period at which temperature 0.6 lb. of diphenyl amine dissolved in SAE grade 30 paratfinic lube oil was added. The reaction mixture was then=further stirred down to a temperature of 200- F. over a 1% hour period at which temperaturethe grease was drawn from the kettle and pumpedthrough three 60-mesh screens into containers. The high temperature grease thus, prepared had the following calculated composition:

The reaction mixture was raised 3:1 menhaden oil-Snodotte acid soap c s 20.2

Excess alkali in charge 1.7 Glycerin (from fat) 1.6 Parafl'inic mineral oil SAE 30 67.5 Aluminum stearate 5.0 Sodium petroleum mahogany sulfonate 3.0 Diphenylamine 1.0 D. C. Anti-foam A p. p. m 220 The properties of the sodium base grease thus prepared are as follows:

Appearance, dark brown, smooth, glossy, buttery.

Min. pene. after 102-103 Torque breakdown machine No. 1, 80-250 F.:

Timken bearing Grease on brg 74 Leakage Overall rating Good Federal bearing- Grease on brg 28 Leakage 0 Good Overall rating Example II I A mixture of 18 lbs. of SAE grade 20 paraffinic mineral lubricating oil fraction, 1.8 lbs. of pale oil solution containing 30.5 weight per cent sodium petroleum mahogany sulfonate, 11.6 lbs. of a 3:1 mixture of menhaden oil-Snodotte acids were charged to a fire-heated kettle wherein they were heated to about a temperature of 150 F. and 6 grams of methyl silicone (Dow Corning Anti-foam A) were added. At 150 F., 5.45 lbs. of a 49.5 per cent solution of sodium hydroxide and 7 lbs. of wash water were added to the reaction mixture. The added caustic comprised the stoichiometric amount required to saponify the soap-forming constituents and 80 per cent of the total 1.9 per cent excess sodium hydroxide. The reaction mixture was raised to 450 F. over a two hour period with the resulting saponification and dehydration of the mixture; at this temperature, 21.6 lbs. of SAE grade 20 parafiinic lube oil was added over a V2 hour period. The mixture was then raised to 550 F. in a 1% hour period and held at this temperature for approxi mately three hours. The reaction mixture was then cooled with stirring to a temperature of 500 F. during a period of about 1 hour whereupon 3.0 lbs. of aluminum stearate was then added over a /2 hour period. The reaction mixture is then stirred down over a three hour period to a temperature of 300 F. whereupon 168 g. of 49.5% solution of sodium hydroxidethe remaining excess sodium hydroxide-and 50 cc. of water were added. After the reaction mixture was stirred down during a 45 minute period to a temperature of 250 F., 0.6 lbs. of diphenylamine dissolved in 1.08 lbs. of 20 grade paraffinic oil was added. After the reaction mixture had been further cooled with stirring over a 1% hour period to 200 F., the grease was drawn and pumped through three 60 mesh screens into containers. The grease thus prepared had the following calculation composition:

Na 3:1 menhaden oil-Snodotte acid soap 20.2 Excess alkali in charge 1.6

Added later 0.3- Glycerin 1.6 Parafiinic mineral oil SAE 20 67.4 Aluminum stearate 5 .0 Sodium petroleum mahogany sulfonate 3.0 Diphenylamine 1.0 D. C. Anti-foam A p. p. m 220 The properties of the sodium base grease thus prepared are as follows:

Appearance, brown, smooth, glossy, buttery.

Dropping point, "F 500+ Unworked pene 305 Worked pene 286 Low Temp. Torque, see./rev. atcw. cew.

0 F 1.8 1 6 -10 F 5. 0 4 2 -20 F 19 17 3o F 72 47 40 F 120 120 Norma Hofiman oxidation, lb./ drop in 500 hr 17-17 Dynamic water resistance, per cent loss 10-17 Torque breakdown machine No. 1, -250 F.:

The foregoing examples illustrate the excellent wide temperature range ball and roller bearing alkali metal greases of this invention. The high dropping points and the good low temperature torque properties are particularly significant. The wide temperature range ball and roller bearing alkali metal greases of this invention find a wide variety of uses because of their excellent properties.

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 are indicated in the appended claims.

We claim:

1. A wide temperature range ball and roller bearing grease characterized by high dropping point and good low temperature torque properties comprising a mixture of 15 to 25 per cent alkali metal soaps of a soap-forming material having an iodine number of at least 90, 60 to 80 per cent mineral oil, 1.3 to 2.3 per cent alkali metal hydroxide, said grease having been prepared by incorporating said soap-forming material in said mineral oil, adding to said mixture an amount of alkali metal hydroxide equivalent to the sum of the stoichiometric quantity required for saponification plus the prescribed excess alkali metal hydroxide, saponifying said mixture,.

ture of menhaden oil and hydrogenated fish oil fatty.

acids, 60 to 80 per cent mineral oil, and 1.3 to 2.3 per cent alkali metal hydroxide, said grease having been prepared by incorporating said soap-forming material in said mineral oil, adding to said mixture an amount of alkali' metal hydroxide equivalent to the sum of the stoichiometric quantity required for saponification plus the prescribed excess alkali metal hydroxide, saponifying; said mixture, raisingsaid mixtureto a temperature of 480 to 550 R, digestingthe mixture at atemperature between 480 and -50- F. for 2 /2 to 5- hours, cooling said digested mixture with stirring toatemperature of about 200 F., and drawingsaid grease about 200 F.

3. A grease according toclaim 2 wherein sodium soaps are employed;

4. A wide temperature range ball and roller bearing grease characterized by high dropping point and good low temperature torque properties comprising a mixture of 15 to 25 per cent alkali metal soaps of a soap-forming material having an iodine number between 90 and 130, 60 to 80 per cent parafiinic. mineral. oil, 0.25 to 4 per cent petroleum. mahogany sultonate salt, l.3 to. 2.3 per cent alkali metal hydroxide and 1 to per cent additives, said grease having been prepared by incorporating said soap-forming material in said mineral oil, adding to said mixture an amount of alkali metal hydroxide equivalent to the sum of the stoichiometric quantity required for saponification plus the prescribed excess alkali metal hydroxide, saponifying said mixture, raising said mixture. to a temperature of 480 to 550 F., digesting the mixture at a temperature between 480 and 550 F. for 2 /2 to 5 hours, cooling said digested mixture with stirring to a temperature ofabout 200 F., incorporating said additives in said grease after said elevated temperature digestion while the grease is being stirred down to a temperature of about 200 F. and drawing said grease about 200 F.

5. A grease. according to claim 4 wherein. the soap formingmaterial comprises a 3 to 1 mixture of menhaden oil and hydrogenated fish oil fatty acids.

6. A grease according to claim 4' wherein the additives are diphenylamine and aluminum stearate.

7. A grease according to claim 4 in which the paraffinic mineral oil is at lease SAE grade 30 and the excess alkali metal hydroxide is in the range of 1.4- to 1.7 weight per cent.

8'. A wide temperature range ball and roller bearing grease characterized by high dropping point and good low temperature torque properties comprising a mixture of to- 25 per cent alkali metal soaps of a soap-forming material having an iodine number between 90 and 130, 60 to 80-per cent paraffinic mineral oil, 0.25 to 4 per cent petroleum mahogany sult'onate salt, 1.3 to 2.3 per cent alkali metal hydroxide, and l to 10 per cent additives, said ,grease having been prepared by incorporating said soapforming material in said mineral oil, adding to said mixture an amount ofalkali metal hydroxide equivalent to the sum of the stoichiometric quantity required for saponificationplus 60 to 80 per cent prescribed excess alkali metal hydroxide, saponifying said mixture, raising said mixture to-a temperature of'480 to 550 F., digesting mixture at a temperature between 480 and 550 F. for 2V2 to 5 hours, cooling said grease mixture with stirring, adding to 40' per cent of said excess alkali metal hydroxide at a temperature of about 300 F., stirring said grease down to a temperature of about 200 F., incorporating said additives in said grease after said elevated temperature digestion while the grease is stirred down to a temperature. of about 200 F., and drawing said grease, about 200 F.

9'. A grease, according to claim 8 wherein the additives are diphenylamine and aluminum stearate.

10. A grease according to claim 8 in which the soapforming material comprises a 3 to 1 mixture of menhaden oil andhydrogenated fish oil fatty acids.

ll. A grease according to claim'8 in which the parafiinic mineral oil is below about SAE grade 20 and the alkali metal hydroxide, content is in the range of 1.7 to 2.1.

12. A grease comprising a wide temperature range ball and roller bearing grease characterized'by high dropping point and good low temperature properties comprising a mixture of 15 to per cent sodium soaps of 3 to- 1 mixture of menhaden oil and hydrogenated fish oil fatty acids, saidmixture having an iodine number of about 110; 60 to 80 per cent parafiinic mineral oil, 0.25 to 4 per cent sodiumpetroleum mahogany sulfonate salt, 1.3- to- 2.3 per centsodium hydroxide, 3 to- 7 per cent aluminum stearate and 0.5 to 3 per cent diphenylamine, said grease having been prepared by incorporating said menhaden oil-hydrogenated fish oil fatty acid mixture in said paraffinic oil, adding to said mixture an amount of sodium hydroxide equivalent to the sum of the stoichiometric quantity required for saponification plus 60 to 80 per cent of the excess sodium hydroxide, saponifying said mixture, raising said mixture to a temperature of 480 to 550 F., digesting the mixture at a temperature between 480 and 550 F. for a period of 3 to 4 hours, cooling said grease mixture with stirring, adding 20 to 40 per cent of said excess sodium hydroxide during said stirred cooling at a temperature of about 300' F., incorporatingsaid diphenylamine and aluminum stearatc in said grease after elevated temperature digestion. during the stirred cooling and drawing said grease after it has been stirred down to a temperature of about 200 F.

13. A grease according to claim 12 in which parafiinic mineral oil is SAE grade and the excess sodium hydroxide is about 1.5 weight per cent.

14. A grease according to claim 12 in which the parafiinic mineral oil is SAE grade 20 and the excess sodiumhydroxide is about L9 per cent.

15. A grease according to claim 12 in which the drawn grease is milled with a resulting 10 F. improvement in its low temperature torque properties.

16. A process for preparing alkali metal greases characterized by high dropping point and good low temperature torque properties which comprises digesting at an elevated temperature of 480 to 550 F. for a period of 2 /2 to 5 hours a saponified dehydrated mixture comprising 15 to 25 per cent alkali metal soaps of a soap-forming material having an iodine number of at least 90, 60 to 80 per cent mineral oil and 1.3 to 2.3 per cent excess alkali metal hydroxide, cooling said digested mixture with stirring to a temperature of about 200 F. and drawing said grease.

17. A process for preparing wide temperature range ball and roller bearing greases characterized by high dropping point and good low temperature torque properties and comprising 15 to 25 per cent alkali metal soaps of a. soap-forming material having an iodine number between 90 and 130, 60 to 80 per cent mineral oil and 1*.3 to 2.3 per cent excess alkali metal hydroxide which comprises adding to a mixture of said soap-forming material and said mineral oil an amount of alkali metal hydroxide equivalent to the sum of the stoichiometric quantity required for saponification plus 60 to 80 per cent of the prescribed excess alkali metal hydroxide, saponifying and dehydrating said mixture, digesting said dehy dratedmixture at a temperature of 480 to 550 F. for a period of 2 /1 to 5 hours, cooling said grease with stirring to a temperature of about 300 F., whereat the residual. 20 to per cent of said alkali metal hydroxide is added, cooling said grease with stirring to a temperature of about 200 F. and drawing said grease.

18. A process for preparing alkali metal greases characterized by high dropping point and good low temperature torque properties which comprises digesting at an elevated: temperature of 480 to 550 F. for a period of 2% to 5 hours a saponified dehydrated mixture comprising 15 to 25' per cent alkali metal soaps of a 3 to 1 mixture of menhaden oil and hydrogenated fish oil fatty acids. to per cent mineral oil and 1.3 to 2.3 per cent excess alkali metal hydroxide, cooling said digested mixture with stirring to a temperature of about 200 F. and drawing said grease.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Zimmer et a1. Dec. 9, 1941 Woods June 13, 1944 5 Morgan Oct. 16, 1945 Zimmer et a1 Dec. 18, 1945 Liehe Feb. 12, 1946 10 Beerbower Nov. 25, 1947 Morway et a1 Apr. 26, 1949 Butcosk Jan. 24, 1950 Rudel Apr. 11, 1950 Morway July 4, 1950 Puryear et a1. Feb. 20, 1951 Morway et a1 Apr. 29, 1952

Claims

1. A WIDE TEMPERATURE RANGE BALL AND ROLLER BEARING GREASE CHARACTERIZED BY HIGH DROPPING POINT AND GOOD LOW TEMPERATURE TORQUE PROPERTIES COMPRISING A MIXTURE OF 15 TO 25 PER CENT ALKALI METAL SOAPS OF A SOAP-FORMING MATERIAL HAVING AN IODINE NUMBER OF AT LEAST 90, 60 TO 80 PER CENT MINERAL OIL, 1.3 TO 2.3 PER CENT ALKALI METAL HYDROXIDE, SAID GREASE HAVING BEEN PREPARED BY INCORPORATING SAID SOAP-FORMING MATERIAL IN SAID MINERAL OIL, ADDING TO SAID MIXTURE AN AMOUNT OF ALKALI METAL HYDROXIDE EQUIVALENT TO THE SUM OF THE STOICHIOMETRIC QUANTITY REQUIRED FOR SAPONIFICATION PLUS THE PRESCRIBED EXCESS ALKALI METAL HYDROXIDE, SAPONIFYING SAID MIXTURE, RAISING SAID MIXTURE TO A TEMPERATURE OF 480 TO 550* F., DIGESTING THE MIXTURE AT A TEMPERATURE BETWEEN 480 AND 550* F. FOR 2 1/2 TO 5 HOURS, COOLING SAID DIGESTED MIXTURE WITH STIRRING TO A TEMPERATURE OF ABOUT 200* F. AND DRAWING SAID GREASE.