US2612473A - Lubricating grease compositions - Google Patents

Description

of the type mentioned abovev may- Patented Sept. 30, 1952 2,612,473 LUBRICATING GREASE COMPOSITIONS Railway.v and Paul v. Smith, 4 J., assignors to Standard Oil Development Company,

ware

No Drawing. Application August 4, 1951,

v Serial 14 Claims.

- 1 The present invention relates to lubricatin grease compositions and particularly to improvements in lubricating greases of the type which comprise lubricating oil thickened to grease con sistency with a combination of high and low molecular weight soaps and salts. The invention relates also to a process for making lubricating greases of soft consistency and a stable physical structure having improved properties over the prior art compositions.

This application is a co-pending application Serial No. on May 28, 1949. i

In the prior art, a number of suggestions have been made for combining the usual soaps, which are used to thicken lubricating oils in the preparation of greases, with certain low molecular weight compounds to improve high temperature properties, increase the yield value or thickening effect of a given soap content, and to secure other advantages. Such suggestions have been applied to various types of lubricating greases. A particular application of practical value has been the addition of such low molecular weight compounds to the alkali metal soap'greases, particularly the soda base greaseaand, to a lesser extent, to the lithium base greases. Lubricating compositions of this type are found to have superior stability at high temperatures, higher dropping points, a firmer consistencyfor a given soap or salt content and certain other useful properties. Along with'the usual :metal soaps continuation-in-part of 96,136, filed of the higher fatty acids, it has been suggested that the corresponding metal salts of acetic acid, acrylic acid, crotonic acid, furoic acid,.and other homologous and analogous compounds may be advantageously combined. The combination of salts of the low molecular weight .acids with the conventional soaps has one common disadvantage in that when suflicient soap is employed to give them structural stabil'ty, the greases tend to be of hard consistency under some conditions, making them somewhat difficult ,toqdispense in certain commercialtypes of grease dispensing equipment. This tends somewhat to limit the utility of the soap-salt type greases. An object of the present invention .is to improve-greases of this type in this: rrespect without adversely affecting their desirableproperties,

According to the present invention, by using a small amount of certainbranched chain aliphatic acids containing sulfur or oxygen, greases be materially improved. The quantities usedare fromabout 1 to 10% bywei'gha-base'd on thetotal com a corporation of Delaposition, along with the usualquantities of fatty late, furoate. orthe like.

the combination of soap and salt" me 4 ing to the present invention a superior acid soap and low molecular weight 581115,. Usin such acids as are describedbelow greasqs of softer consistency may be made with the same general properties of high temperaturestability, high melting point, and the like; In effect, soaps of these branched chain sulfuror oxy gnrbear ing acids are substituted forpartpf the conventional soap.

In general, the invention contemplates the use of small amounts of the; soaps of branched chain sulfuror oxygen-bearing acids alongwith the low molecular weight salts and the conventional metal soap of fatty acids. The latter conventional soaps are preferably thoseadeflved from the fatty acids of between,-12,;;and 24 carbon atoms,'especially'those hayingbetween 14 and 20 carbon atoms. The ;soaps-;of the saturated long chain acids-.orthQSe which are substantially saturated are normally' preferred. allowever, ,soapsof the -long,chain unsaturated acids may be usedfoli many purposes ,ias the-principal thickening ingredient; ,Witlrsuchsoapis combined preferably a somewhat smaller quantity of the pr f red low: molecul r wgi htsa Such as thepacetate. propi n t a ma amethwy- The metal ion ;is,..pref erably but .notnecessarily the same asthat of the principal soap. Proportions of 2 or 3 to 2 0 or 25% by weight of conventional soap, i plus 1 may th total composition, the preferred range be g;;between abouts l or to 20%, Qap. I9 .lq,% .l

to 15% oftheloyv molecular weight salt or approximately in ,1 1 molar ratio for most applications. I I

Greases thickened to a solid consistenc with .99 msv o exture and better softness and stability, may ,besecurfed by combining l to ,'10%, preferably: 2 ted "by above, ,haye fairly good properties, bu t weight, based on'tlieitotal composition-of av high molecular weight branched aliphatic? ainlioizygen-or sulfur-bearingsoap. A suitable te for this latterpurpo'se is one .which is prepared, by

neutralizing with anappropriate'metal base an wherein X is selected from the group consisting of oxygen and -sulfur,: R is an-alkyl radicalcon taining at least two tertiary. carbonratoms, and

R and n are of .suchvaluethat the total-,rmmber 12 to 18 carbon atoms.

acids may be neutralized with sodium hydroxide {well-known Cannizzaro reaction.

'furfural may be obtained the corresponding 'furoic acid salt and furfuryl alcohol. This aspect of the process has previously been covered in a acids.

. a 3 20. The oxygen or sulfur atom may be positioned at various points in the chain.

The acids of the type exemplified in the above formula may be prepared by reacting aliphatic alcohols and mercaptans, preferably branched chain .s'i bstantially saturated aliphatic com.- pounds nf-this type, with a suitable acidogenic material, preferably an aliphatic unsaturated acidogenic material such as acrylonitrile. The mercaptans themselves may be obtained from various sources, a preferred source being by the reaction of polyolefins with hydrogen sulfide. For example, diisobutylene, triisobutylene, polypropylene and analogous polymers and copoly- 'mers of appropriate molecular weight (about 8 to 16 carbon atoms, preferably) may be converted to mercaptans and reacted with acryloni trile or equivalent acidic or acidogenic materials, as pointed out more fullybelow. Thesoaps (or salt) of such mercaptan type acids may be formed: by neutralization with a suitable metal base in an obvious manner.

The soap, the low molecular weight salt,- and the salt of-the'branched chain oxygenor sulfurbearing acid may all be formed simultaneously by combining the acids first, preferably in the presence of a quantity of mineral lubricatin oil, and then coneutralizing the various acids with a saponifying agent. Thus, there may be combined inmineral oil a commercial mixture of hydrogenated fish-oil acids varying from about 14 to 22 carbon atoms in chain length and of an average of about 18 carbon atoms, together with acrylic, g'lycollic or furoic acid as a low molecular weight acid, and with a sulfur or oxygen bearing acid described more fully below but having about This combination. of

to produce a grease containing all three soaps (salts) which is a very satisfactory product. Alternatively, the low molecular weight acid may, in effect, be added to-the other ingredients by I jfirst adding the corresponding aldehyde which, i when treated with a stronger alkaline base such as sodium hydroxide, simultaneously with the neutralization of the other acids, undergoes the Thusv from copending application, Serial N0.'60,615', filed Nove'm ber 17, 1948, by Morway, one of the-present inventors, and a co-inventor Kolfenbach, now

"United States Patent No. 2,516,137, issuedJuly v 25,1950, where there is disclosed a process for preparing greases containing furoic acid salts and analogous products, by using the Cannizzaro reaction. The Cannizzaro reaction is equally useful in the present case, the product being "beneficially modified, howev'en'by the-addition of the "high molecular weight, branched chain,

' sulfure (or oxygen-) bearingsalt which'gives the lubricant the desirable soft consistency and other properties mentioned above.

Another aspect of the present invention intvolves the preparation of the sulfur bearing 'An aliphatic unsaturatednitrile having the unsaturation adjacent the nitrile group, such as acrylonitrile, methacrylonitrile, ethacrylonit'rile, etc., may be reacted with a branched chain aliphatic mercaptan derived as suggested above or fromany other suitable sourceto produce a sulfur-bearingacid of the type, desired fonpreparin the salt referred to above. The alcohols may :be used in place ofthe. mercaptanslf de-.,

= temperature of 300 rapidly by using 'ture preferably below about 45 C., for example.

The thionitrile thus formed is thereafter hydrolyzed to the sodium soap or salt of the acid by adding an alcoholic-aqueous NaOH solution. If the soap of another metal is desired, the solution is acidified, e. g., with HCl. Upon acidification in a conventional manner, the acid is produced, although if desired the sodium salt may be employed directly in the grease, in which event, acidification is not necessary.

The oxygenor sulfur-bearing acid derived as above, in proportions of about 1 to 10 parts, preferably 2 to 5 parts by weight,- is combined with 2 to 20, preferably 3 gar-4 to 15, parts of saponifiable fatty acid and l to. 15, preferably 2 to 10 parts of the low molecular weight acid;

Theoxygenor;sulfur-bearing acids, or their salts, may also be formed directly in the grease by incorporating the nitrile and the mercaptan or alcohol and hydrolyzing with sodium hydroxide or other appropriate strong base In this case, ammonia is evolvedwhile the sulfur-bearing salt (or soap), the conventional soap, and the. low molecular Weight salt are all bein formed in situ.

As previously noted, the low molecular weight acid may be a saturatedacid such as acetic or propionic acid, an unsaturated acid such as acrylic acid, or a cyclic or heterocyclic acid such as furoic acid. Alternatively, acidogenic ingredients may be used which will result in the production of such acids. For-example, the appropriate aldehydes may be used which are subjected to the Cannizzaro reaction.

The, various acids are preferably mixed together as a solution or slurry in at least a part of the lubricatin oil, usually a mineral base lubricating oil. The quantity of oil used initially during soap, and salt formation may be varied rather widely. Preferably-it is of about the same order as .the added acids and should usually be less than the total quantity of oil used in the final-grease so that a further quantity of oil may be worked intothe soap-salt composition later. The acidic ingredients are then saponified or coneutralized in the presence of the oil, and the remainder of the oil desiredin the finished product is added after neutralization is substantially complete. Thereafter, the: whole mixture is cooked in-the usual manner, forexample, to a to 500.2101: more. When cooking-is completed, other conventional ingredients such as an anti-oxidant, e.ig., phenyl alpha naphthylamine metal deactivators, tackiness agents, load bearing may be added.

compounds, and the like, .The product may .be'cooled a continuous cooler .or may be allowed to stand for cooling in: pans ma conventional mannerb-Preferably, .the. grease is stirred or homogenized. after-cooling and it is then readyforpackaging... 1 i

It will thus be appreciated. theta distinct reainvention is, the use of oxygen- Which are preferablydewhich contain alcohol which contains stage a total of about '10 to about 2 carbons atoms per lubricating grease is expected to perform extreme pressure functions. In such cases, ,sulfurized mer- ..captans or acids may be used. In other cases, an

sulfur atom in the chain is quite satisfactory. The high molecular weight oxa-acids, i. e., those of 8 or more carbon atoms branching in the hydrocarbon chain, have the branched chain characteristics desired and 'ar'e'qu'ite useful.

acid containing one Qxa-acids of the-following ,gjeneralformulas may be used; v .(1) Br-O CHICHi QOH (2) .R QwH-CODH 3)" 0H,

arm d-coon wherein R1 is an alkyl radical derived from an branched groups as heretofore described. Specific acids include 717,9,9- tetramethyl 4 oxade'canoic acid; "1,99,11,11-

pentamethyl-l-oxa dod-ecanoic acid; 6,6,8',Btetramethyl 3 o-xa-nonanoic acid; 6,8,-8,10,1 0-pentamethyl 3 oxa undecanoicacid and the like. Acids derived from oxo alcohols will generally be mixtures of highly-branched compounds containing at least two tertiary carbons atoms per molecule, I

These sulfur-bearing or oxygen-bearing acids may be prepared also by reacting the C3 or higher oxo alcoholsior-other branched chain alcohols) or mercaptans, with-laetones, such as fl-propiolactone. They may be formed also by reacting salts ofmercaptans or alkoxides with halonitriles or halo-acids, e. g., chloroacetonitrile, ,B-chloropropionic acid, etc.

The invention may be more fully understood by reference to the following specific examples: I I Example I I i A mixed" C13 of low molecular weight olefins with carbon monoxide and hydrogen. The alcohol included a mixture of highly branched, isomeric C13 alcohols having at least two tertiary carbon atoms in the chain, Substantially equimolar amounts of the alcohol and B-chloropropionic acid were reacted to form an acid having the generalformula canaownmcoon Thefollowing formulation was then prepared.

15.0 weight percent C13H2'1O(CH2)J2COOH 6.0"weight percentiuroic acid.

5.2:weight percentNaOH.

1.0 weightpercentphenyl alpha naphthyla-mine 72.8 weight percent mineral lubricating oil (55 S. S. U. vis. at 210 F.)

until the soap-oil mixture was dehydrated (to "6x0" alcohol was prepared by conventional catalytic oxonation of C12 polymers tion of the balance of the oil F.) The-grease was cooled to F. and passed smooth, sh

form a firm and'stable grease.

"abode asoi-isoo firo j} eantime or "thefts-was slowly addedf, 'and heating was'continued until the temperature reached 5 00" j The naphthylamine joxidationiinhibitor 'was then 'adde'd. The molten in fthe'pans. .The cooledfgrease had the following properties: 4 I Appearance... excellent,':smooth, short fibers Penetration,:mm./i0,*779 p 1 Unworked 265 Worked (60 strokes) 2'70 a Worked (100,000 strokes) :-.290 Dropping'point; PE. 1 500+ Norma Hoffmann oxidation, hours- 15:00 1

1 Tea 5 p. s. 1. drop in oxygeu'pressure. Example :11

v The following formulation was prepared: 10.00 weight percent furfu-ral 10.00 weight percent fattyacids (hydrogenated fish oil acids having Cmaverage chainlength) 5.00 weight percent ether carboxylic acid (of. the

same type usedin Example!) 5.18 weight percent NaQI-I j 5 e e 1.00 weight percent phenyl alpha naphthylamine 68.82. weight percent mineral oil (sameasi that usedinExampleI) V a Q The. fatty acid and ether acid and one-halfo-f the mineral oil were charged to a steam-heated grease kettle and sodium hydroxide (33 /3970 aqueous solution) was added in a manner similarto theprocedure used inExample I. After theheat of reaction had subsided, the furf-ural was added and reacted with the excess NaOH that had not reacted with the previously added acids. After completion of the Cannizzaro reaction, the mass was heated to 250' F. to dehydrate the soap. Heating-was continued during addi- (upto about 325 through a Lancaster disperser. It had excellent, ort fibers, a-dropping point above 500 F. and penetrations of 275, 2-80 and- 335, respectively, for unworked grease and grease worked at 60 strokes and. 100,000" strokes. Thegrease was insoluble in water up to a temperature of F.

Examples for grease preparations, including thioethertype carboxylic acids, are given in aforementioned Ser1alNo.'96 ,136, which examples are incorporated herein by reference for convenience. a A.

Apparently "the ether type acid alone is not an adequate grease thickening. ingredient'an-d the composition requires at least amodest proportion of the fatty acids of the usual type to This is true whether the low molecular weight salts are used or notQWithout the latter, larger quantities of fatty acid soaps usually are needed.

The low molecular weight acids shouldhave a molecular weight in the acid radical of not more than about and preferably not more than about 120. The best compositions apparently arethose which contain all three acid salt or soap ingredients, namely, the conventional long chain fatty acid soap, the salt of low molecular weight, and the soap of the branched chain sulfuroroxygen-bearing aliphatic acid of 10 to 20 carbon atoms. While the alkali metal soaps and salts of these acids are preferred formed in situ by reacting cohols of 8 to about waste 7 and specifically thesoda or lithium compounds; other metals mayjbe used anclamixtureof the soaps of one metal, salts of another metal, andthesulfur-bearing soap of either, both or a third'and difierent metal may be combined. Ordinarily, and preferably as a matter of convenience, the soaps and salts are I a single metal base therewith, and they are therefore most easily formed simultaneously. Simultaneous neutralization is not preferred, however, when the Cannizzaro reaction is employed, in which case the low molecular weight salt should, of course, be prepared first. However, for economy, the sodium salt or a concentrated aqueous solution may be employed with no degradation in the quality of I the product. a

While, in general, the oxygenor sulfur-bearing acid has a preferred molecular content of about '15 carbon atoms, suitable acids may be prepared by reacting aliphatic unsaturated nitriles, or the like, of 3 to about 10 carbon atoms with branched chain aliphatic mercaptans or al- 18 carbon atoms, the reactants being so' selected that the resulting acid will have not more than 20 nor less than 10 carbon atoms, as previously stated.

The usual or conventionalmodifiers or additives such as antioxidants, metal deactivators, tackiness or stringiness agents, extreme pressure compounds, and the like, may be employed, as is 'Well understood by those skilled in the art. The

lubricating oil is preferably a mineral base oil, but may be a synthetic ester or polyglycoloil in many cases. Where the Cannizzaro reaction is used, the oil which is present during the reaction should be a hydrocarbon or substantially hydrocarbon product since esters are hydrolyzed under the conditions of the C'annizzaro reaction. In such cases, esters may be added after the soap and salt forming reactions-are substantially com,

pleted.

What is claimed is:

1. A lubricating grease composition comprising a major proportion of lubricating oil thickened to a'grease consistency with a combination of a metal soap of'fatty acids having between 12- and 24 carbon atoms, a metal salt of an-organic acid having a molecular weight below about 160, and a metal soap of a branched chain aliphatic'carare tertiary and having at age in the chain.

2. A lubricating least one ether linkgrease composition comprising I a'major proportion of lubricating oil and a minor boxylic acid having between about 10 and about 20 carbon atoms, of which at least 2 carbon atoms acid having between 12 and 24 carbon atoms, an

alkali metal salt of an organic acid of molecular weight below about 160, and an alkali metal salt of a branched chain aliphatic carboxylic' acid having between 10 and 20 "carbon atoms, of which at least 2 carbon atoms are tertiary, and having at least one ether linkage in the chain.

is an alkaline] earth metal.

metal is lithium.

5. Composition as in claim 1 wherein the metal 6. Composition as in'claim 1 wherein the acid of molecular weight below is a heterocyclic acid. .'J

7. Composition as in claim 1 wherein the acid of molecular weight'below l60'is furoic acid.

' 8;."A lubricatinggre'ase composition comprising a major proportion of mineral base lubricating oil thickened to a grease consistency with a thickener consisting essentially of 2 to 20%1by weight, based on the total composition, of a metal soap of fatty acid, said acid-having a molecular chain length within thei range of 12 to 24 carbon atoms, 1 to 15% of a metal salt of organic acid which has a molecular weight below about 160, and 1 to 15% of metalisoap of branched chain aliphatic carboxylic acid having between 10 and 20 carbon atoms and one ether linkage in the chain. v

9. Composition as in claim 8 wherein the metals are alkali metals.

10. Composition, as in claim v8 wherein all .of the metals are the same metal.

' 11. Composition asin, claim 8 wherein the metals are alkaline .earth'metals.

12. Composition asin claim 8 wherein all the metals are sodium.-

13. Composition as in metals arelithium:

14. The process of preparing a lubricating grease composition which comprises simultaneously forming a soap,.a low molecular weight salt, and a salt of high molecular weight oxygen bearing aliphatic acid, by reacting a combination of fatty acid, an aldehyde having a low molecular weight radical corresponding to said first. mentioned salt, and a branched chain aliphatic carboxylic acid having at least one ether linkage in the chain, with a saponifying compound of metal base to convert saidfatty acid to soap, convert said ,aldehyde'to acid and alcohol and thence said last mentioned acid to salt, and convert said aliphatic carboxylic acid to salt in the presence of a lubricating oil, thereby thickening said oil to grease consistency.

ARNOLD J. MORWAY.

7 h PAUL v. SMITH, JR.

' REFERENCES CITEDI claim 8 wherein all the file of this patentz.

UNITED STATES PATENTS Number Name Date 2,455,892 Fraser Dec. 7, 1948 2,468,099 Morway Apr. 26, 1949 2,514,286 Morway July 4, 1950 2,516,136 Morway et al. July 25, 1950 2,516,137 Morway et al. July 25, 1950 2,586,693 Morway et al Feb. 19, 1952

Claims (1)

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A COMBINATION OF A METAL SOAP OF FATTY ACIDS HAVING BETWEEN 1I AND 24 CARBON ATOMS, A METAL SALT OF AN ORGANIC ACID HAVING A MOLECULAR WEIGHT BELOW ABOUT 160, AND A METAL SOAP OF A BRANCHED CHAIN ALIPHATIC CARBOXYLIC ACID HAVING BETWEEN ABOUT 10 AND ABOUT 20 CARBON ATOMS, OF WHICH AT LEAST 2 CARBON ATOMS ARE TERTIARY AND HAVING AT LEAST ONE ETHER LINKAGE IN THE CHAIN.