US2628938A

US2628938A - Production of greases using reaction products of alpha-hydroxy fatty acids

Info

Publication number: US2628938A
Application number: US150355A
Authority: US
Inventors: William B Whitney
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1950-03-17
Filing date: 1950-03-17
Publication date: 1953-02-17
Anticipated expiration: 1970-02-17

Description

and the resulting cooled material is :then ,to produce asmooth: grease;

Patented Feb. 17, 1953 UNITED STATES PATENT OFFICE PRODUCTION "OF GREASES 'USIN G REAG- .TION- PRODUCTS F- ALPHA-.HYDROXY FATTY ACIDS William Bpwhitney, Bartlesville, 0kla., assignmto Phillips Petroleum Companypa corporation oflDelaware yNoiDrawing. Application'March17,1950,

. Serial No. 150,355

smoothgrase with little tendency to bleed.- .In

l14'Claims. (01.252441) '2 I have also found that the "reaction product, formed. upon esterifieation of the hydroxy group of the'hydroxy fattyacid'with one or more molecules of such an acid, when convertedto a metal salt, is an excellent gelation agent forlubricat- *ingoil greases.

Thus, accordin to the invention, ajuncture I product of a hydroxy fatty acid, preferably an still another of itsaspects the invention relates .to noveligel type lubricatin greases having. little te'ndencyto bleed. It is well known that greases can be made by dissolving :or dispersing under suitable conditions a "fatty acidsoap in a suitable hydrocarbon oil The particular type of grease produced'depends, of course, upon the method by which it is produced. A fiber grease isusually produced by l'IllX- ing th'e proper? proportions of oil,ifat, andaqueous caustic soda'and heating to saponify the fat and to evaporate the water formed as .well'as any duced by slow cooling and mixing withadditional oil. Agel grease is produced by mixing a suitable fatty'acid soap, usually in an amountfrom 5 to per cent, witha hydrocarbon oil and heating to a temperature somewhat above the solution temperature. Upon effecting solution, the mate- :rialiscooled sufiiciently rapidly that substantiallyino separationof. soap and. oil takes place, worked ;In making.:ge1 greases, the soap'is usuallyan alkali metal :salt of a fatty. acidof 18 carbon atoms or higher. The "sodium and potassium salts of 'palmitic acid (16 carbon atoms) can only occasionally be used, .and those of less than 16 carbon atoms do not appear to be compatible with the oils insofar asmakinggrease isconcerned.

Lithium salts of fatty acids having 16, 14, and

.sometimes .12 carbon atoms per molecule can often be used. The oil used in the 'manufacture of the grease determines how short a chain can be successfully used.

[I have now found thatmetal salts of jthereac- 'tion'pro'cluct of an hydroxy fatty acid, especially alph'a-hydroxy fatty acid, with "at least one-other molecule of such an acid, and/or with another fatty acid, is produced; converted to a metal salt and then used in the production-of a gel type lu'bricating grease. In place of the fatty acidother acylating agents can also *be used. For example, the acid anhydrides -or the-acid chlorides of the fatty acids can be used. Also a polymerized hydroxy fatty acid can 'be reacted to "form a mixture of a metal saltof the polymer and a metal salt of a fatty acid and-said'mixturecan-thenbe-used as a grease gelation'agent.

The following description and examples read in conjunction with the preceding portion 'of-this specification will indicate fully and clearly the scope of theappendecl claims to the invention so that one skilled in the grease production art will be enabledto prepare any of the products to which reference is made. A now-preferred elation agent of the "invention is that which is formed by the reaction of analpha-hydroxy fatty acid with a fatty acid. Therefore, the following portion of the'descriptionrelates-to said reaction.

The general process for the production'of the gelation agents from an alpha-hydroxy fatty'acid and a fatty acid comprisesheating the fatty acid and alpha-hydroxy-fatty acid'in the liquid phase "for a sufiicient length of time to efiect'reaction,

usually from 1 to 12 hours. A condensation'cata- "lyst suchas zinc chloride'can be used. [Thereac- Operation at atmospheric pressure is ordinarily preferred, but elevated pressure can be used Where necessary.

The reaction which takes place, at least 'to a large extent-appears to be ROOOH +R'CHOHCOOH R-CH,COOH +"H,o

Rooo wherein R and "R' represent alkyl-grou and total number ofcarbonatomsin R'+R is: at 'leas "16 and 'preferably'at leas't 18.

Several specific procedures, not necessarily either as separate streams or as a mixture.

molecule.

completely equivalent methods, for carrying out the reaction can be used. In some instances one or more of these methods will be found to be preferred over another.

The simplest method for carrying out the illustrated reaction is to heat a mixture of the fatty acid and hydroxy fatty acid, the fatty acid being present at least in an amount molecularly equivalent to the hydroxy fatty acid. The product is then neutralized to produce the sodium salt, and the neutral product is used to produce a gel grease with a hydrocarbon oil.

In a second method, the reaction vessel initially contains only a heated quantity of fatty acid, and the alpha-hydroxy fatty acid is then slowly added with agitation. In this manner, the concentration of the reactive hydroxy acid is kept low and the reaction is directed toward juncture of the fatty acid and hydroxy fatty acid, because the opportunity for two hydroxy fatty acid molecules to react has been minimized. After the reaction has been effected, neutralization of the acid constituents to form sodium salts and the making of the grease is carried out.

The reaction may also be carried out in a continuous system. In such a method, the fatty acid and hydroxy fatty acid are continuously charged to a reaction zone in the desired proportions, A stream of the reaction mixture equal to the materials charged is continuously drawn off. Neutralization and making of the grease is carried out as before.

In some instances, it may be desirable to effect even further direction of the reaction to that of the fatty acid with the alpha-hydroxyl group. This may be done by maintaining at all times the fatty acid in molecular excess over the unreacted alpha-hydroxy fatty acid in the reaction zone. The excess fatty acid may be removed from the reaction mixture, withdrawn and recycled to the reaction zone prior to neutralization. However, in those instances where this excess is not objectionable in the final utilization, none or only a part may be removed prior to neutralization.

In choosing the starting reactants, it is desirable to choose a pair which will yield a juncture product of at least 16 carbon atoms per molecule, and preferably 18 or more carbon atoms per As noted,. a partial esterification of the alpha-hydroxy fatty acid with itself can occur. However, these dimers should be considered on the basis of total available monomer,

disregarding any dimerization, when calculating the moles in any given quantity of hydroxy fatty acid. 7

Although not as desirable a method as those previously described, an alpha-hydroxy fatty acid can be polymerized and subsequently reacted to form a mixture of the sodium salts of the polymer I acid that may be converted to a soap suitable for use in a grease.

These gelation agents can also be used with the synthetic ester, diester and polyester lubricating oils, or with polyalkalene oxide lubricating oils,

although it is noted especially that an ester oil is no t required and that according to the inven- 4 tion greases with lubricating oils can be prepared with little or no working by simple admixture and heating of the gelation agent and a lubricating oil.

It is to be noted thatthe gelation agents of this invention produce greases of excellent resistance to bleeding.

Example I Example II In a second trial, it was attempted to produce a gel grease from the mixed sodium salts of lauric acid and alpha-hydroxydecanoi-c acid. This mixture of salts did not produce a grease. These salts individually are not gelation agents.

Example III In another test, alpha-hydroxydecanoic acid as the only reactant was heated for three hours at C. and one hour additional at' 200 C.

The resulting material was neutralized with sodium hydroxide and this sodium salt mixed with sodium laurate. The mixed salts were then used successfully as a gelation agent in making a gel grease from a hydrocarbon oil.

Example IV Portions of alpha-hydroxydecanoic acid were separately reacted by the previously-described procedure in mixture with stearic acid and in mixture with oleic acid. Each product was converted to the sodium salt and then successfully used as the gelation agent for making a gel grease from hydrocarbon oil.

From Examples I and II it can be noted that the neutralized reaction product of lauric acid and alpha-hydroxydecanoic acids acted as a gelation agent whereas a mixture of the sodium salts of these acids did not so act. However, in Example III, where the alpha-hydroxydecanoic acid was the only reactant and it was reacted with itself, then neutralized and then mixed with sodium laurate a successful gelation agent was obtained. Example IV shows that substitution of stearic and oleic acids, respectively, for the lauri-c acid of Example I was successful.

Although this specification is directed mainly to the use of sodium soaps of the disclosed condensed acids, it should be understood that other metal soaps may be used. These include soaps of other alkali metals, suchas potassium and lithium, soaps of the alkaline earth metals, such as calcium, strontium, and barium, and also soaps of aluminum and of magnesium. The soaps of the difierent metals are not necessarily full equivalents, and this fact must be borne in mind when specific applications of the invention are contemplated. Mixtures of the soaps of two or more metals may be used as grease gelation agents within the broad scope of this invention.

- Other alpha-hydroxyacids usable in the process of the invention are alpha-hydroxyoctanoic acids, alpha-hydroxydodecanoic acids, alpha-hydr-oxy hexadecanoic acids.

Variation and modification are possible within the scope of the foregoing disclosure and the appended claims to the invention the essence of which is that certain hydroxy fatty acid, preferably alpha-hydroxy fatty acid, reaction products have been prepared, and when converted to sodium salts, these products have been found to produce smooth gel type lubricating greases with little or no working being required and the grease having little or no appreciable tendency to bleed; this without necessary recourse to any ester oil.

I claim:

1. The production of a gel type lubricating grease which comprises effecting an esterification juncture of an hydroxy fatty acid with at least one of an hydroxy fatty acid and another fatty acid to produce a juncture product having at least sixteen car's-on atoms to the molecule; converting the juncture product to a metal salt; and admixing said salt with a suitable lubricating oil to produce said grease.

2. A production according to claim 1 wherein the juncture is effected at an elevated temperature suilicient to cause reaction to occur and the reaction mass is maintained at said temperature for a time suflicient to complete the reaction.

3. A production according to claim 2 wherein the temperature is in the range 125 to 250 C.

4. A production according to claim 3 wherein the temperature initially is lower than finally and the initial temperature is maintained for a substantial period of the reaction.

5. The production of a gel type lubricating grease which comprises effecting an esterification juncture of alpha-hydroxydecanoic acid (2-hydroxy-4,6,6-trimethylheptanoic acid) with at least one material selected from the group consisting of said acid itself and another fatty acid to produce a juncture product having at least sixteen carbon atoms to the molecule; converting the juncture product to sodium salt; and then admixing said salt with a suitable lubricating oil to produce said grease.

6. A production according to claim 5 wherein the other fatty acid when used is selected from the group consisting of lauric, stearic and oleic acids.

7. A production according to claim 6 wherein the juncture is effected at a temperature in the approximate range 125 to 250 C.

8. A gel type lubricating grease the essential gelation agent of which is a metal salt of an and 'esterificatiorri-juncture product of an hydroxy fatty acid with a material selected from the group consisting of an hydroxy fatty acid and another fatty acid said product containing at least sixteen carbon atoms.

9. A grease according to claim 8 consisting essentially of said gelation agent and a suitable lubricating oil.

10. A grease according to claim 8 wherein the hydroxy fatty acid is 2-hydroxy-4,6,G-trimethylheptanoic acid and the other fatty acid is selected from the group consisting of lauric, stearic and oleic acids.

11. A gel type lubricating grease the gelation agent of which is an admixture of the sodium salt of an esterificati on juncture product of alphahydroxydeoanoic acid (2-hydroxy-4,6,6-trimethylheptanoic acid) with itself and sodium laurate.

12. The preparation of a gel-type lubricating grease which comprises heating an hydroxy fatty acid with at least one of an hydroxy fatty acid and another fatty acid, in the liquid phase at-a temperature in the approximate range -250 0., for a time in the range of from about 1 hour to about 12 hours, to produce a product having at least 16 carbon atoms to the molecule; converting the product thus produced to a metal salt; admixing the salt thus obtained with a lubricating oil; heating the admixture to form a blend of said salt and said lubricating oil; and then cooling said blend sufficiently rapidly, so that no substantial separation of the salt and oil can occur, to form said grease.

13. A preparation according to claim 12 wherein the hydroxy fatty acid is at least one acid selected from the group consisting of alpha-hydroxy-octanoic acid, alpha-hydroxydecanoic acid, alpha-hydroxydodecanoic acid, and alpha-hydroxyhexadecanoic acid and the said another fatty acid is at least one acid selected from the J group consisting of lauric acid, palmitic acid,

stearic acid and oleic acid.

14. A preparation according to claim 12 in which a small amount of zinc chloride is employed as a catalyst during the first heating step.

WILLIAM B. WHITNEY.

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

UNITED STATES PATENTS Number Name Date 1,927,296 Powers Sept. 19, 1933 2,334,274 Meadows Nov. 16, 1943 2,375,530 De Groote et al. May 8, 1945 2,397,956 Fraser Apr. 9, 1946 2,450,220 Ashburn et al Sept. 28, 1948 2,452,092 Ault Oct. 26, 1948 FOREIGN PATENTS Number Country Date 615,188 Great Britain Jan. 3, 1949

Claims

1. THE PRODUCTION OF A GEL TYPE LUBRICATING GREASE WHICH COMPRISES EFFECTING AN ESTERIFICATION JUNCTURE OF AN HYDROXY FATTY ACID WITH AT LEAST ONE OF AN HYDROXY FATTY ACID AND ANOTHER FATTY ACID TO PRODUCE A JUNCTURE PRODUCT HAVING AT LEAST SIXTEEN CARBON ATOMS TO THE MOLECULE; CONVERTING THE JUNCTURE PRODUCT TO A METAL SALT; AND ADMIXING SAID SALT WITH A SUITABLE LUBRICATING OIL TO PRODUCE SAID GREASE.