US2801969A - Lubricating greases thickened with soaps obtained by alkali fusion of amino alcohols - Google Patents

Description

LUBRICATING GREASES THICKENED WITH SOAPS OBTAINED BY ALKALI FUSION OF AMINO ALCOHOLS A rnold J. Morway, Rallway, and Jefirey H. Bartlett, West field, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware Application February 2, 1953, Serial No 334,717

11 Claims. (Cl. 252-33.6)

No Drawing.

The present invention relates to an improved method of preparing lubricating greases and to grease compositions produced by this method. More specifically, the invention pertains to improvements in the manufacture of grease thickeners and to greases containing such thickeners. In its broadest aspect, the invention provides an improved method of preparing amino acids and grease thickeners by fusing high molecular weight amino derivatives having a primary alcohol group, particularly amino ether alcohols, with caustic alkali, producing a metal soap from the amino acid so formed and incorporating this metal soap into a lubricating oil in grease making proportions. In a preferred embodiment of the invention, the fusion is carried out in the presence of lubricating oil.

Lubricating greases normally consist of lubricating oils thickened by alkali and alkaline earth metal soaps or other thickeners to a solid or semi-solid consistency. The soaps may be prepared by the neutralization of high molecular Weight fatty acids or by the saponification of fats which is usually carried out in a portion of the oil to be thickened.

The present invention pertains to highly valuable, stable lubricating greases in which the high molecular weight fatty acids are replaced or at least supplemented by a new grease making material. It has now been found that such greasesmay be prepared by incorporating into lubricating oils a grease thickener obtained by fusing high molecular weight amino derivatives having. a primary alcohol group, particularly amino ether alcohols, with alkali, particularly caustic soda or potash at temperatures of about 400620 F., preferably about 500-575 F. fora time sufiicient to form the alkali metal salt ofthe acid corresponding to the amino alcohol used. The chemical reaction taking place during the fusion process may be illustrated by the following equation:

E- CHzCI-IzOH-l-MOH 2Hz-l-E- CHzCOOM (1) wherein E may be an amino or an amino ether radical containing 1 or more carbon atoms and M is an alkali metal, such as sodium or potassium. The amino or amino ether alcohol should contain a total of at least carbon atoms per molecule.

The discovery of the utility of alkali fusion of high molecular weight amino alcohols for grease making greatly increases the Wealth of raw materials available for grease production. Heretofore, ester-type fats, oils or high molecular Weight fatty acids have been used almost exclusively in the manufacture of soap-thickened greases and these starting materials have been believed indispensable for the purpose. All these materials have numerous other industrial uses, a situation conducive to the development of shortages forcing undesirable variations in grease making procedures and grease characteristics. The discovery of an entirely new and large class of suitable raw materials cases this situation considerably.

The use of high molecular weight amino alcohols as grease making materials introduces no complication into the grease making procedure. While alkali fusion of the ice amino alcohol may be carried out in a separate preliminary acid-forming stage, the greases are preferably produced essentially in a single process step in which the high molecular weight amino alcohol is fused with alkali in the lubricating oil base in greasemaking proportions and atgrease making conditions, although at somewhat higher temperatures. At the conclusion of the fusion process a finished grease is obtained.

Quite generally, amino alcohols, particularly amino ether alcohols, may be used which have about 10-50 or,

more carbon atoms per molecule and a s'utficiently high boiling point to prevent excessive volatilization during the fusion process. The amino alcohols suitable for the invention have the general formula and yield upon alkali fusion ether acids of the formula wherein R=a hydrocarbon group containing from 1-40 carbon atoms selected from the group consisting of alkyl, alkylene, naphthenyl, aryl, alkaryl and aralkyl R and R: H or one of the groups represented by R y=an integer from 0-50 x=0 or 1, z=l or 2, and x+z=2.

These amino alcohols include the amino derivatives of alkylene or polyalkylene (e. g. ethylene, propylene, polyethylene, polypropylene) glycols. Specific examples of these compounds are:

TYPE B R-N- (C HO H2- O) ,C H-CH OH monoalkylamino alkoxy i alkanol H II RI I or monoalkylamlno alkanol =alkylamino bis (alkoxy alkanol) or alkylamino bis alkanol Examples:

Monoethylamino-decapropoxypropanol Monolaurylamino octadecapropoxydodecaethoxyi ethanol Mono-coco-amino -eicosaethoxyethanol Mono-stearylamino-ethanol Toluino-pentadecaethoxyethanol TYPE C R.N-(CH-C Hz-O) OE-43H; OH= dialkylamino alkoxy alkanol I R V I RI! or dialkylamlno alkanol perived from mon0-cocoamine made by reduction of the nitnles of cocoanut oil acids.

Patented Aug. 6, 1957? 3 Examplesi Diethylamino-pentadecaethoxyethanol Dioctylaminodecaethoxyethanol Octyl laurylamino-decaethoxyethanol Diphenylamino-triacontaethoxyethanol Dicetylamino-tetraethoxyethanol Dilaurylaminodipropoxypropanol Di-coco-amino ethanol Di-coco-amino pentapropoxydiethoxyethanol Di coco amino ---triethoxydipropoxytetraethoxyethanol Didodecylamino-ethanol Particularly desirable starting materials are the amino and amino ether alcohols obtained from primary or secondary aliphatic amines, particularly straight chain amines, such as octadecyl amine, lauryl amine, etc.

"The amino and amino ether alcohols to be subjected to alkali fusion in accordance with the invention may be prepared from these starting materials quite generally by a reaction with alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, nonylene oxide, hexadecene oxide, butadiene monoxide, styrene monoxide, etc., at temperatures of about 2l2 F. in the presence or absence of catalysts, for example an alkaline type catalyst, to form monoglycol or polyglycol ethers having a primary alcohol group. The amount of alkylene oxide used may be as high as 50 or more mols for each mol of the amino compound used as the starting material.

The water and oil solubility of this end product may be controlled to a certain degree by a proper choice of the molecular Weight of the alkylene oxide used. In general, the higher the molecular weight of the alkylene oxide the lower the water solubility and the higher the oil solubility of theend product. Thus, water insoluble, oil soluble end products may be produced by combining the low molecular weight amino compounds with high molecular weight alkylene oxides.

The reactions involved in the formation of suitable amino alcohols from amino compounds and alkylene oxides may be illustrated by the following equations: R-IFH (11-1-1) R"-CHCH2 The amino or amino ether alcohols produced in this manner may then be converted into the corresponding carboxylic acids or their soaps by fusion with alkali as described above and illustrated with reference to Equation 1. While the acids and soaps may be produced in a separate process step and the preformed products incorporated into lubricating oils in grease making proportions, a particular advantage of the present invention resides in the fact thatthe new grease thickeners may be prepared in situ in the lubricating oil as an integral stage of the grease making process. In other words, the amino alcohols may be converted into soaps by alkali fusion in'the grease kettle using the lubricating oil base of the grease as a reaction medium.

When carrying out this preferred embodiment of the invention, it has been observed that the alkali has a strong tendecy to settle out of the reaction mixture to the bottom of the reactor in the form of a cake which does not fully participate in the reaction. Highly efiicient stirring or agitation will counteract this tendency. However, in many cases more efficient stirring is required than may be obtained in conventional grease kettles and special equipment is necessary.

This settling tendency of the alkali in the lubricating oilamino alcohol mixture is negligible when a sufficient amount of a solid suspending agent is present in the reaction mixture. Most desirable suspending agents are those which serve simultaneously as grease thickeners, such as soaps of high molecular weight fatty acids, silica gel, carbon black, bentones, Attapulgus clay modifications, etc.

Soaps, particularly sodium soaps of high molecular Weight fatty acids, are preferred for this purpose. Howin accordance with a speclfic embodiment of the invention by using the salt, preferably the alkali metal salt, of a low molecular weight acid in addition to the high molecular weight fatty acid soap. In this manner, soapsalt complexes are formed which melt well above 500 F. and thus form an excellent suspending agent.

These soaps or soap-salt complexes are preferably formed in situ by neutralization of the corresponding acids in the amino alcohol-oil mixture with alkali added in amounts sufficient ,for this neutralization and the subsequent fusion which takes place at considerably higher temperatures. High molecular weight acids useful for this purpose include hydrogenated fish oil acids, C1z-Cz2 naturally occurring acids of animal or vegetable origin, etc. These acids may be used in amounts ranging from about 2-30 wt. percent based on the finished product. Suitable low molecular weight acids include acetic, furoic, acrylic and similar acids to be used in proportions of about 1-10 wt. percent based on the finished product. Esters, e. g. glycerides of the high and/or low molecular weight acids, particularly those containing mono basic acid esters may be used in place of the free acids in corresponding proportions. In this case, the alcohol portions of the esters are converted into acids and the corresponding soaps by alkali fusion. If esters of low molecular weight alcohols are used, elevated pressures may be employed to prevent volatilization of the alcohols. Of course, esters of nonvolatile low molecular weight alcohols, such as polyhydroxy alcohol esters, e. g. sorbitol acetate, glycol acetate, etc., may be used. Particularly the high molecular weight type of acids or their esters used for this purpose may also be prepared by alkali fusion of amino alcohols. In this case, a portion of the product of the alkali fusion process in which the principal grease thickener is prepared in accordance with the invention may be returned to the fusion stage to serve as an agent preventing settling of the alkali.

Soaps of high molecular Weight fatty acids and/or soap-salt complexes of the type specified may be incorporated in the greases of the present invention to improve high temperature or other characteristics even if no suspending agents are required. Thus, when soaps derived from branched-chain amino alcohols are employed it is often desirable to incorporate soaps derived from straight-chain fatty acids in order to obtain greases having particular structure characteristics.

The soaps formed by alkali fusion of amino alcohols in the presence of other fatty acid soaps yield excellent smooth greases. Other conventional thickeners, antioxidants, corrosion inhibitors, tackiness agents, loadcarrying compounds, viscosity index improvers, oiliness agents, and the like may be added prior, during and/ or after the fusion process as will be apparent to those skilled in the art.

The'base oil used as rnenstruum during the fusion process should'be a mineral lubricating oil. After the fusion is completed, synthetic lubricating oils, such as a dibasic acid ester (e. g. di-Z-ethyl hexyl sebaca te, adipate, etc.), polyglycol type synthetic oils, esters of dibasic acids and polyhydric alcohols, etc, as well as alkyl silicates,--carbonates, formals, acetals, etc., may be This difiiculty may be overcome;

.="alkali per mol of amino alcohol.

. t used alone or in addition to mineral lubricating oil to bring the grease to the desired consistency. The oil base preferably comprises about 50 to about 95% of the total weight of the finished grease.

. As indicated above, the alkali fusion of the invention may becarried out in two stages. When so operating,

theamino alcohol to be fused may be added in the initial charge or over a period of 1-8 hours to a molten rrliixture of alkali and mineral oil, maintained atfusion tegrnperatures of, 'say, about 400-620 F. The amount of alkali employed may be substantially stoichiometric hr somewhat higher, for example from 1-3 mols of When all the amino alcohol has been added, heating may be continued at these temperatures until 1 gas evolution substantially ceases. The acid formed may be recovered from the reaction mixture after cooling, by dilution with water or with 50% isopropanol, followed by extraction of the oil and any unreacted alcohol with a suitable solvent,

such as heptane or the like, and acidification. If desired, the free acid may be purified by vacuum distillation.

The acid so prepared may then be introduced into a alkali, preferably in aqueous solution, to neutralize the acids present. Conventional grease making conditions including temperatures of about 350-500 F. may be used in this stage. The soap derived from the amino alcohol by alkali fusion should form at least wt. percent and preferably about -50 wt. percent of the grease thickener or about 20-20 wt. percent of the finished grease. is preferably made up by a suitable soap-salt complex of the type described above. The proportion of soap derived from amino alcohol to soaps and salts derived from other acids may be about 1:4 to 4:1 and preferably is about 1:1. i

The free amino polyether acids and also their soaps may be used as additives in lubricating oils. By controlling the length of the alkyl group and the polyether groups, the resulting acids may be valuable in the production of oil soluble chelates and the soaps may be valuable as detergents. A

In order to prepare a grease by alkali fusion of the amino alcohol in situ in accordance with a more desirable embodiment of the invention, procedure may be quite generally as follows. A mineral lubricating oil base is mixed with the amino alcohol and the mixture is heated to about 130-180 F.

The alkali is added preferably in the form of an aqueous solution of about 3050% concentration. The mass is then dehydrated at temperatures of about 300-400 F. for about 1-6 hours, depending upon the size of the batch. Thereafter, the temperature is increased to a fusion temperature of about 400-620 F. and maintained within this range until gas formation has receded appreciably, which takes place usually after about 1-2 hours. The grease may then be allowed to cool under stirring to about 200 250 F. at which level further additives may be introduced. Finally, the grease may be poured into pans to be cooled to room temperature.

A similar procedure is employed when the amino alcohol is subjected to alkali fusion in situ in the pres ence of suspending agents, such as soaps of high mo- 'lecular weight fatty acids or complexes of such soaps with salts of low molecular weight acids in accordance with the preferred embodiment of the invention. In

The remainder of the grease thickener the grease making.

this case, the high molecular weight acids are added to the mineral oil together with the amino alcohol while the low molecular weight acid may be added after the initial heating stage immediately prior to. the alkali addition.

Thereafter, sufficient caustic alkali to neutralize the acids 6. and convert the amino alcohol to soap is added, preferably in the form of an aqueous solution of about 40-50% and the mixture is heated at a. saponification temperature of about 300 400 F. until the acids are converted to soaps and salts and all the water is volatilized. Alkali fusion is then carried out substantially as described above, except that less violent stirring is required.

The invention will be best understood by reference to the following specific examples which represent preferred modifications of the invention.

Example I Dicocoaminoethanol having the formula N-GHz-CHzOH (average molecular weight approximately 425) was prepared by reacting ethylene oxide with dicocoamine manufactured by Armour and Company by reduction of the nitriles of coconut oil acids. The dicocoaminoethanol was used in grease manufacture as follows:

1 Hydrogenated-fish oil acids, having a degree of unsaturation corresponding approximately to commercial stearic acid.

PREPARATION The dicocoaminoethanol, the Hydrofol acids 54 and /2 of the mineral oil were charged to a fire heated kettle equipped with means of good agitation. The ingredients were warmed to 170 F. and the acetic acid. was charged thereto, followed immediately by a 40% aqueous solution of the sodium hydroxide. Heating was continued at 400 F. until the mixture was dehydrated. The balance of the mineral oil was added and heating continued to 560 F. At this temperature a suddenlarge expansion in the kettle contents occurred, which slowly subsided. Heating at 560 F. was continued for minutes. The grease was solid at this temperature Heating was discontinued but stirring continued while cooling to 250 F. wherethe phenyl alpha-naphthylamine was added. Cooling was then continued to 200 F. Properties:

Dropping point, F 500+. Penetration, mm./10; 77 F:

Unworked 136. Worked 60 strokes 160. Worked 100,000 strokes Water washing test, per- 1 cent loss Norma Hoifmann oxidation test, hours to 5 p. s. i. Drop in oxygen pressure Appearance None.

Excellent smooth uniform 7 Example II the aai ae assi t ssssl i2 thi as nsta Eth meea 17 a 259W; 9?? A .1 @1251. @qitipans li q ae n "W in? he BRSQ I ta genera ormu a (9191 E: It st nds, for a h drocarbon ra aldesired. iit talle and con sti g o b u saturated C16 groups, 70%, saturated Q1}; groups and 5% unsaturated C18 groups. This amino alcohol is made by reacting tallow acids with ammonia to form the ammonium Salt t these ear s heatin t9. dehydrate the sa to the amide, further dehydrating the latter to form the nitrile, reducing the nitrile to the amine and reacting this amine with ethylene oxide per mol of amine.

Ingredients: Weight percent .rli liylaaiias t H Blend of nap "nic type mineral oil distillate having a viscosity of 55 S. S. U. at 210 FL- 68.50

PREPARATION Th Hydrofol i s ,.Et119mea li. and. 4 he, miIiTI-IaI'5i'1V5i 5h S'UQ afii t h ated; rea ke tl war'md to l SO FI acetic acid,was;added, fol;- lo'w'ed immediateIybyYaAQWO agueous solution of NaOH; The temperature was raised to 400 E., volatilizing water. iil l he ama he netal;q li asadd d at g wascontinued to- 560--F-. and: the temperature heldabove 500 F. for 2 hours. Then heatingwas discontinued and the mass allowed to cool while agitating. When a temperature of 275-f was reachedl' the inhibitor (phenyl alphaY- naphthylamine was added and the mass I cooled to throughaliomogeuiier, filteredfand packaged. ress? Dropping point F 500+ Penetrations, 77- F.- mm./ 10:

Unwor ked- 199- Worked- 60 strokes 7 Worked 60,;000 strokes Water .washing test, percent loss None;

=b 1a1 qPfi=fih-. isasa sft ii-t e ket l s ilu e as follows? 50% above described product 50% solvent extracted Mid-Conti-nent distillate+solvent Q extracted Bright Stock, havinga viscosity of 57' S. S; U. at 210 F. and a V. I.=' 0f;102.*

This product was homogeniged, filtered and packaged.

Properties:

Dropping point, F 47.2 Penetrations, 77 F. mm./10.! v

Unworked 310 Worked 60 strokes 320 Worked 100,000 strokes 33,2

Water; a i-ngtes per e t 0 Q n in. pxxsenp e surs 214 The invention is not limited to theaspeoific figures of wherein R is. an alkyl hydrocarbon group containing fronzi l carbon atoms, 3! is an integer from 0-50,v x is at;

integer from. 0 to 1, z is an integer from 1 to 2, and

grease thickner is made up of, about 30 to wt. percent of the alkali metal soap derived from the amino alcohol,. and the remainder is made up of an alkali metal soap of a high molecular weight fattyacid.

3. A grease according to. claim 1, wherein said grease thickener is made up of. about 30 to 50 wt. percent oithe alkali metal soap derivedfrom: the amino alcohol. and the remainder is-made up of: a complex of. a: high molecular Weight fatty acid soap with a low molecular Weight fatty acid salt;

4. Agrease according to-claim: l. which containsa minor amount ofa suspending agent, whichis solid at the: conditiqns of fusion, suflicientitoprevent the alkali fI01'nS6ttling; out; of the: reactionlmixture during said fusion.

5 A; grease according; to; claim=1 in which. said alcohol has. the general: formula,

6; Agreaseaccording-toyclaim- 1; in which" said: alcohol aSal'tta eneral. formula 7.- The-process: of preparing a a: lubricating; grease com position which comprises admixing a major proportion'of. a mineral lubricating; oilgwith; an. amino. alcohol having about 101050, carbon-atoms; per; molecule and having. he general. formula,

wherein Ris an alkylhydroearbon group. containing from carbon atom s,,y is.,an integer. from 0 5 0;,x is.an integer from 0j toll, zuis aninteger from'1.to.2,.andx+ z is 2, heating saidmixturento a-temperature ofabout 130to 180 Ff, then adding ,an. amount ofialkalisufli cienttorfusing said jaminotaljcohol, dehydrating theresulting mixtureata temperatu-reofabout 300"to 400F'.,.. continuing heating at a temperature off about 400 to 620TF'. until gas evolution substantially ceases and-Jth'en cooling the resulting grease composition, said amino. alcohol being employ ed in anamount sufficientto form about 2",to 20;;wt.. p ercent, of'a grease thick'eningalkali" metal soap 8: The process for preparing lubricating grease compositions, which comprises admixing a major proportion of a mineral lubricating oil, about 2 to,30 wt. percent, based on the finished grease composition, ofla high molecular weight fatty acid and an amino alcohol having about 10" to 50carbon atoms per molecule and having thegeneral formula 2, hea-tin'g 'saidrniXture -to a temperature of about 130 10 adding to the heated mixtureeabout 1 "to 10%"- A re se according to claim 1 wherein the said by weight; based on the finished "grease cornposition tof-a ent alkali for fusing said amino alcohol and for nutralizing said high and low molecular weight carboxylic acids, dehydrating the resulting mixture at a temperature of about 300 to 400 F., continuing heating at a temperature of about 400 to 620 F. until gas evolution substantially ceases and then cooling the resulting grease composition, said amino alcohol being employed in an amount suflicient to form about 2 to 20 wt. percent of a grease-thickening alkali metal soap.

9. The process of claim 8 wherein the high molecular weight/fatty acid is a hydrogenated fish oil acid and said low molecular weight carboxylic acid is acetic acid.

10. The process of claim 8 wherein said amino alcohol is dicocoamino ethanol.

11. The process of claim 9 wherein said amino alcohol has a molecular weight of 491 and the approximate formula CHIOH2Oh-B wherein R is a hydrocarbon radical of tallow acid.

References Cited in the file of this patent UNITED STATES PATENTS Kokatnur Apr. 24, 1928 Reid May 3, 1932 Pelton et a1 Sept. 12, 1933 Strosacker et a1 Sept. 12, 1933 Strosacker et al. Nov. 7, 1933 Wilmanns Feb. 14, 1939 Platz et al. July 4, 1939 Haussmann et a1 Dec. 19, 1939 Stephenson et a1 Apr. 9, 1940 Kokatnur Aug. 20, 1940 Curme et al Sept. 18, 1945 Chitwood Sept. 18, 1945 Curme et al Sept. 18, 1945 Billman Jan. 6, 1948 Bryant eta]. July 22, 1952 Bryant June 2, 1953

Claims (1)

1. A LUBRICATING GREASE COMPRISING A LUBRICATING OIL AND A GREASE MAKING PROPORTION OF A GREASE THICKENER COMPPRISING AN ALKALI METAL SOAP OF AN ORGANIC ACID PRODUCED BY FUSING AN AMINO ALCOHOL WITH ALKALI AT A TEMPERATURE IN THE RANGE OF 400 TO 620* F. UBTIL GAS EVELUTION SUBSTANTIALLY CEASES, SAID ALCOHOL HAVING ABOUT 10 TO 50 CARBON ATOMS PER MOLECULE AND HAVING THE GENERAL FORMULA