US2417428A - Lubricating composition - Google Patents

Description

Fatentecl 18, 194? OFFICE LUBRICATING COMPOSITION Lester W. McLennan, El Cerrito, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application September 19, 1946, Serial No. 697,911

16 Claims.

This invention relates to lubricating composi tions containing metal soap complex" and processes for their production and is a continuationin-part of my copending applications, Serial Nos. 586,028, 586,029 and 586,030, which in turn are continuations-in-part of my prior application, Serial No. 469,894; Serial No. 588,719 which is a continuation-in-part of my prior application Serial No. 473 217 and Serial No. 589,941.

The object of the invention is to obtain all the benefits in such lubricants and greases as are peculiar to metal soap complexes. Such complexes produce stable greases which have excellent melting point and penetration characteristics, do not require hydration, have exceptional resistance to deterioration by the action of heat and by the action of moisture, including boiling water, and generally have unusual thickening effects on lubricating oils, even at relatively low concentrations. An especialy important fact is that in general stable greases are formed with high viscosity oils of both paraflinic and naphthenic types. Another object of this invention is to provide processes for the manufacture of basic metal soap lubricants.

By the term metal soap complex as used in this application, it is meant to include products which are substantially neutral or substantially free from readily titratable excess alkalinity, at least beyond a relatively small amount; and in which the ratio of equivalents of combined metal to equivalents of saponified higher molecular weight organic acids is greater than 1.1 to 1 and preferably is greater than about 1.2 to 1. De-

pending upon the particular saponifiable material, saponification reagent and upon the characteristics of the mineral oil employed, it is preferred that this ratio be between about 1.2 to 1 and 2 to l but it may be as high as 3 to 1 or even as high as 4 to 1.

By the term normal metal soap as used in this application, it is meant to include those products which result when one equivalentof a metal hydroxide or other basically reacting metal compound is reacted with one equivalent of a saponifiable material to form a soap, said soap being the normal metal salt of the higher molecular weight organic acid, present as such or derivable by saponification from thesaponifiable material.

By the terms saponification reagent, base, basic metal compound or basically reacting metal com pound used herein, it is meant to include the various oxides, hydroxides and/or hydrated oxides of those metals which will form salts or soaps with fatty acids, such as stearic acid, oleic acid, etc.

Among others the terms saponification reagent, base, basic metal compound or basically reacting metal compound will include the oxides, hydroxides and/or hydrated oxides of the "strongly basic metals, namely, the alkali metals, i. e., lithium, sodium and potassium and the alkaline earth metals, i. e., calcium, strontium and barium and the weakly basic metals, such as the metals of the right hand column of group II of the periodic table, i. e., beryllium, magnesium, zinc and cadmium, the metals of the right hand column of group III, i. e., aluminum, indium and gallium, the metals of the right hand column of group IV, i. e., lead, tin and germanium, the metals of the left hand column of group VI, i. e., chromium and molybdenum and the metals of the iron group of group VIII, i. e., iron, cobalt and nickel. The periodic table referred to is that form of Mendeleeffs periodic arrangement of the elements shown in Handbook of Chemistry and Physics, 25th edition, 1941-1942, pages 308-309.

Examples of saponifiable materials containing higher molecular weight organic acids present as such or readily derivable therefrom by saponification include fats such as tallow, lard oil, hog fat, horse fat, etc., higher molecular weight organic acids such as stearic acid, oleic acid, the higher molecular weight acids resulting from the oxidation of petroleum fractions (for example, parafiin wax and mineral oil), rosin and related products, higher molecular weight naphthenic acids, sulfom'c acids, etc., and saponifiable waxes such as beeswax, sperm oil, degras, etc.

The present invention resides in lubricating compositions, especially greases, which contain metal soap complexes which are substantially neutral or substantially free from readily titratable excess alkalinity. While the invention may be extended to freely fluid lubricants, such as Diesel engine lubricating oils containing small proportions of metal soap complexes, it includes more particularly the use of such metal soap complexes in proportions to thicken lubricating oils appreciably for the purpose of producing liquid greases or solid greases of varying consistencies. More articularly, the invention resides in mineral oil lubricants containing thickening proportions of metal soap complexes where the ratio of equivalents of combined metal to equivalents of saponified higher molecular weight organic acids is between about 1.2 and 2, although it extends to the upper limit above indicated, 1. e., 4 to 1, and may be as low as 1.1 to 1. Especially stable metal soap complex greases have been found to have a ratio within the range of 1.3 to 1 and 1.9 to 1. The invention also comprises the method oi! making such lubricants.-

The invention also includes the use of metal soap complexes to produce lubricants employinghigh viscosity mineral oils, ,e. g., 50 or 70 S. A. E.

grade or even bright stocks as well as lower visconditions it is possible to react one equivalent weight of a saponifiable material (as determined by its saponlflcation number) with more than about 1.1 and up to about twice the equivalent.

weight (or even up to a ratio of 4, as above in-' dicated) of a saponiflcation reagent such as a basically reacting metal compound, for example,

a metal hydroxide .or hydrate, at elevated temperatures in the presence of oxygen and preferably in the presence of a polar solvent such as water, to produce a material which is substan-- tially neutral or free from readily titratable excess alkalinity. Similarly it is possible to react 1 equivalent weight of a normal soap with more than about 0.1 and up to about 2 equivalents, or

even as high as 3 equivalents of a'basically reacting metal compound to produce a material which is with strontium hydroxide. Thi complex has a diflerent solubility in oil than normal strontium soap alone but still contains the strontium hydroxide in a readily titratable form.v It is probable, therefore, that the material actually undergoing oxidation is the normal metal soap-metal hydroxide complex.

One of the principal oxidation products which results when one equivalent of a fat, saponifiable wax, or a higher molecular weight saponifiable organic acid is reacted with about 1.1 or more equivalents of a basically reacting metal compound under the conditions as disclosed in the present invention and illustrated in the subsequent examples, is acetic acid present in the final product as metal acetate. In addition, appreciable amounts of carbon dioxide and relatively smaller amounts of other low molecular weight carboxylic acids, such as formic acid, propionic acid, oxalic acid, etc.,,also. appear to be formed and are present in the final product as the corsubstantially neutral or free from readily titrat-f able excess alkalinity. This reaction is carried as described herein.

In preparing greases the above-described-reae 40 tion may be carried-out in the presence of a part or all of themineralbii be employed injthe final productzunderdahese'eonditions the mineral out inthegres'ence of oxygen and will preferably be carriedout in the'presence of a n'elar solvent;

responding metal salts.- of oxidation coming within the scope of the present invention, metal carbonatemay be the principal salt formed and may be preferred for certain combinations of mineral oil and saponifiable materials. V

I have also discoveredthat metal soap complex greases having some of the desirable prop erties of metal soap complex'greases formed by reacting, for example, 2.0 equivalents of a basically reacting metal compound with one equivalent of a fat, saponifiable wax, 'or a higher molecular weight saponiiiablaorganic acid, can be ob-- tained'by-mixin'g one-moi of the normal metal of the same fat, saponifiable wax, or higher molecular weight saponifiable organic acid with lubricating (oil, adding one. moi of an aqueous solution of: metal acetate and then heating to an elevated. t

a perature to eiTect dehydration and "dispersion in. the lubricating oil. Also, greases,

even more closely resembling those obtained by reacting about 2.0 equivalents, of a basically reoil appears toserve essentially as an inert dil'uent. On the other hand, the 'saponifiiablema terial can be reacted withthe saponiflcation, re-

agent in the absence of mineral oil thereby form ing a "concentra which can be subsequently compounded with mineral oil to form a grease.

The purposes of the polar solvent, oxygen and excess saponification reagent will become evident in the following disclosure.

Although I do'not wish to be limited by the theories advanced herein, the net reaction which appears to occur and which results in the formation of the improved greases forming the subject of this invention is the oxidation of a portion of the saponiflable material and reaction of the excess saponiflcation reagent with the acidic products formed. It is likely that the initial reaction which occurs is the formation of a normal metal soap by the saponification of the saponifiable material with an equivalent amount of the basically reacting metal compound. Subsequently, a portion of the normal soap which may be in the formof a soap-base complex is oxidized by oxygen and the excess basically reacting metal compound present combines with the acidic materials formed. The character of the oxidation reaction which occurs is undoubtedly influenced by the presence of the excess basically reacting metal compound and by the presence of a polar solvent, such as water or glycerine. In this connection evidence has been obtained indicating that in the presence of a polar solvent such as water, normal strontium soap forms a complex lactin's' metal compound itn e equivalent r r a fat, 's'aponifiable wax, or higher molecular weight --Isaponifiable organic acidyand having substan- "tially all of the desirable characteristics of those vgreases have beenobtaine d by combining v one "mol of a normal metal soap'ofthe same fat, sa. ponifiable ,wax, or higher molecular weight saponifiable organic acid with 0.5 mol of metal acetate and 0.5 mol of metal carbonate and dispersing the resultant product in lubricating'oil.

I have also discovered that metal soap complex greases can be formed, not only by the addition of normal metal soap and metal acetate to a lubricating oil or normal metal soap, metal acetate, and metalcarbonate to lubricating oil, but also by compounding normal metal soap, lubricating oil, and a variety of other metal salts.

Metal salts which are useful for the foregoing purpose include preferably the simple reaction products resulting from the combination of one equivalent of a metal oxide orhydroxide, with one equivalent of a mineral acid or of an organic acid of relatively low molecular weight. However, I may also employ acidic or basic salts in which one equivalent of metal oxide or hydroxide has been reacted with more or less than one equivalent of a mineral acid or acid anhydride such as sulfuric acid, hydrochloric acid, orthophosphoric acid, pyrophosphoric acid, sulfurous acid, carbonic acid, boric acid, thiosulfuric acid, etc., S02, S03, 002, etc. I-may also employ metal salts of organic acids of relatively Under some conditions low molecular weight which are relatively insoluble in lubricating oil. As examples may be cited the metal salts of monocarboxylic and polycarboxylic acids containing less than about '7 carbon atoms per molecule, such as formic, acetic, propionic, valeric, oxalic, malonic, succinic, etc., acids, the low molecular weight alkyl and aryl sulfonic acids, the low molecular weight substituted carboxylic acids, such as glyceric, glycolic, thioglycolic, etc., acids, the low molecular weight phenolic and thiophenolic compounds such as phenol, cresol, thiophenol, etc.

In the case of greases coming within the scope of the present invention, I prefer to employ a complex of a normal metal soap with a metal carbonate -or with a metal salt of a monocarboxylic acid having less than about 7, carbon atoms or a mixture of any two or more of such complexes, either as such or in admixture with normal metal soap. In the case of greases to be used under acidic conditions, such as are encountered in the canning industry, it may be desirable to employ a complex of a normal metal soap with a metal oxide, or hydroxide in conjunction with the preferred complexes listed above. It is also within the scope of my invention to incorporate an alkaline-type filler, such as zinc oxide in the finished grease in order to overcome the efiects of any acid liquors with which the greases may come in contact. In accordance with the present invention of using as lubricants metal soap complexes compounded in mineral oil, I prefer to employ more than 0.1 equivalents and preferably more than 0.2 equivalents and desirably between 0.3 and 0.9 equivalents and as high as 2.0 equivalents or even as much as 3.0 equivalents of a metal salt in conjunction with one equivalent of a normal metal soap as the metal soap complex to be compounded with mineral oil to form the lubricants of the present invention.

It is not meant to intimate that any given metal salt is the full equivalent of any other metal salt of the same or different metal for modifying the characteristics of a dispersion of normal metal soap in lubricating oil. In fact, the complexes of various metal salts with a given normal metal soap vary over a wide range as regards their respective solubilities in a given mineral lubricating oil. For example, a normal metal stearate-metal carbonate complex is more solu ble in a given mineral oil than is a normal metal stearate-metal formate complex. Likewise, the latter' complex appears to be more soluble than one formed from normal metal stearate and metal acetate. Complexes of a given normal metal soap with certain metal salts will possess just the proper characteristics to form with a specific mineral oil a grease of the improved properties described herein. Other complexes of the same normal metal soap with different metal salts will be either too soluble or insufliciently soluble to form desirable greases in the given mineral oil. In the latter case it is possible and desirable to form excellent greases coming within the scope of the present invention by mixing a complex which is too soluble in the specific mineral oil with one possessing inadequate solubility. The exact proportions of the two complexes will depend upon the relative solubilities of the two complexes and can be readily determined by one skilled in the grease-making art.

It has also been noted that even though the final grease is to be substantially anhydrous, a product of improved characteristicscanoften be obtained by adding a small amount of water, for example, in the range of 0.1 to 3.0% by weight or even as high as 10% by weight of the grease charge at a suitable temperature and subsequently increasing the temperature to effect substantially complete dehydration. The grease may be at a temperature of about 210 F. or less when such Water additions are made, although temperatures as high as 230 F. or even as high as 300 F. or higher may be used, and subsequent dehydration has been accomplished by heating to temperatures in the neighborhood of 250 F. or higher when necessary. With certain saponification reagents the greases produced by the processes of the present invention have a granular appearance, but by employing the hydration-dehydration technic, products of smooth buttery texture are obtained often accompanied by an increase in consistency and melting point. Fur-- ther improvements in grease texture can likewise usually be obtained by working the grease at temperatures below about 200 F. and preferably below about F. prior to final packaging.

Normally in reacting a saponifiable material with an excess of a basically reacting metal compound the extent of the oxidation reaction is controlled so as to produce a final grease which is substantially neutral or free from readily titratable excess alkalinity, that is, one having a free acid or free alkali content less than about the equivalent of 5.0 mg. KOH per gram of soap present. In other Words, the oxidation is so controlled that it results in the formation of at least about 0.1 equivalent of acidic oxidation products and preferably about 0.2 to 1.0 equivalent of acidic oxidation products or even as high as about 3.0 equivalents of acidic oxidation products. The

progress of the oxidation reaction can be followedby periodically titrating to determine the proportion of metal hydroxide present in the reacting mass, which was not combined with acidic oxidation products and when this has reached the desired value, the oxidation may be arrested such as by rapidly cooling to a temperature below about 250 F. to 300 F, While it is preferred that the soaps in greases of this invention be substantially neutral, they may contain a small amount of free acidity or alkalinity. The finished grease may have a free alkali content calculated as metal hydroxide as high as about 0.5% by weight of grease or a free acid content equivalent to about 2.0 mg. K0 per gram of grease. A grease having a free acid content may be obtained by either continuing the oxidation to produce an excess of acidic reaction products over that required to neutralize the free metal hydroxide or the oxidation reaction can be stopped at an earlier stage, such as while free metal hydroxide is still prescut, and fatty acid or other acidic materials added in sufficient quantity to give a grease of the desired free acid content. In order to obtain a free alkali content the oxidation can be stopped at an intermediate point or it can be continued to produce a substantially neutral oreven acidic soap and the desired excess of .free hasically reacting metal compound then added.

Usually the hydration-dehydration technique to produce a final substantially anhydrous grease is most effective on a slightly acidic grease. Subsequently the grease can be adjusted to the desired acidity or alkalinity by the addition of metal hydroxide or acid, as the case may be. In a similar manner metal soap complex greases prepared by compounding normal metal soaps with metal salts can be rendered acidic or alkaline as de- 7 i sired by adding fatty acids or other acidic materials or metal hydroxide or otherbasically reacting metal compounds, as the case may be.

Free alkalinity is measured in accordance with A. S. T. M. method of test No. D-128-40, section temperatures favor the formation of metal: salts of low molecular .weightcarboxylic acids'so that 18, except that titration is conducted in the cold and the titration is made directly with standard HCl solution rather than byadding an excess of HCl solution and then back titrating with alcoholic'potassium hydroxide solution; Free acidity is measured in accordance with A. S. T. M. method of test No. D-128-40, section 20. Briefly, the methods of test employed are as follows:

A 10 gram sample of the grease is weighed to the nearest tenth of a gram into a 250 ml. Erlenmeyer flask. To the flask is then added 75 ml. of petroleum ether and 50 ml. of 95% alcohol containing phenolphthalein indicator, which has been previously made neutral as indicated by the phenolphthalein indicator. The flask is stoppered and shaken vigorously in the cold until the grease has completely disintegrated and no lumps remain. The solution is then allowed to settle and free alkali or free acid, as observed by the color of the alcoholic layer, is titrated carefully in the cold to the phenolphthalein end point with 0.5 normal H] or alcoholic KO H, as required. Free alkalinity is calculated in terms of metal hydroxide; free acidity in terms of oleic acid or acetic acid. Free alkalinity and free acidity may also be expressed in terms of equivalent mg. of KOH per gram of grease or soap as desired.

Since the formation of metal soap complexes from a fat, saponifiable wax or higher molecular weight saponifiable organic, acid and an excess of a basically reacting metal compound involves an oxidation reaction, it is necessary that this reaction be conducted in the presenceof air or other oxygen-containing gas. The oxidation may be eifected in open kettles at ordinary atmospheric pressure in which case air or oxygen may be blown into the kettle charge or the charge may be aerated by agitation designed to incorporate sufficient amounts of air into the kettle charge to effect the desired oxidation. The open kettle method is generally employed in those instances in which the ingredients selected have an affinity for the polar solvent and can retain the required proportions of polar solvent to promote the desired reactions at the temperatures employed. In

some instances, however, and particularly when the reactions are slow or when the reacting mass will not retain suflicient polar solvent, the saponification and the oxidation may be conducted under superatmospheric pressure in a closed ket-' tie to which the necessary polar solvent and oxygen or oxygen-containing gases are supplied. 0peration in a closed vessel generally permits closer control of the oxidation reaction because in this case the evaporation. of polar solvent can be prevented and the quantity of oxygen employed can be closely regulated. Moreover, the use of superatmospheric pressures, such as are obtainable in closed kettles, generally permits a reduction in the temperature required to efiect the desired oxidation.

The oxidation is conducted preferably at temperaturesbetween about 300 F. and 550 F., however, the particular temperature employed in any given case will depend upon other conditions, such as pressure, the particular saponiflcation reagent and saponifiable material employed and upon the amount and character of the mineral oil employed. In general, the higher temperatures favor the formation of metal carbonate and lower it is possible by control of temperature to vary the relative proportions .of soap-carbonate and s0aI carboxylate complexes in the oxidation product.

indicated herein'above, in order-for the desired'oxidation' reaction and nonnal metal soapmetal salt complex formation'to proceed within the preferred temperature range it is desirable.

that at least a small percentageof a polar sol-. vent, in the neighborhood of at least about 0.1%

by weight of the reacting mass, be present. Further, it appears that preferably this polar solvent should be water, although under some conditions and particularly in the case of oxidizing alkali metal soaps in the presence of alkali metal hydroxide the oxidation and complex formation proceeds more readily in the presence of amixture of water and glycerine, water and glycol, or

with some hydroxy or polyhydroxy organic compound, such as ethyl alcohol, diethylene glycol, etc. Preferably the proportion of polar solvent present should be in the range of 0.5% to 4.0% by weight of the reacting mass, but under some conditions smaller quantities, such as about 0.1% and higher quantities, such as about 10% can be used. As an indication of the desirability of having at least a small percentage of a polar solvent present, I have observed in the case of certain an- I hydrous normal strontium soaps that when mixed with anhydrous strontium hydroxide and heated in the presence of oxygen at a temperature of 350 F. to 500 F. for three hours and the'mixture subsequently analyzed, it was found that little or no reaction had occurred and substantially all of the strontium hydroxidecould be recovered unchanged. Further, if the same mixtures containing an added 0.5% of water were heated in a closed kettle under the same conditions'but with oxygen excluded, little or no reaction was observed to take place. However,

when the same mixture containing 0.5% of added water was heated for three hours in contact with" air or oxygen and at a temperature of 350" F. to

500 F., the resulting product contained normalstrontium soap along with strontium carbonate and the strontium salts of organic acidic oxidation products, and a corresponding amount. of the strontium hydroxide had disappeared.

One of the preferred methods of forming metal soap complex lubricants from a normal metal soap, a metal salt, and mineral oil is to dissolve the normal metal soap in all or only a portion of the mineral oil to be used and subsequently add a solution or a dispersion of the desired metal salt or metal salts in a polar solvent, intimately mix and then while continuing the mixing boil oil. or evaporate all or a portion of the polar solvent. Additional oil can be added during or after the removal of the polar solvent, if desired. The normal metal soap can be preformed or it can be made in the presence or absence of the mineral oil by reacting a saponifiable material with a basically reacting metal compound, by methods known to those skilled in the art.

Another preferred method of forming a metal soap complex lubricant from a normal metal soap, a metal salt, or salts, and mineral oil is to dissolve the desired normal metal soap in mineral oil or form the normal soap from the desired saponifiable material and a basically reacting metal compound in the presence of all or a part of the desired mineral oil. Subsequently, a complex is formed between the normal metalsoap and metal oxide or hydroxide, added in an amount equivalent to the amount of salt which it is desired to complex with the normal metal soap, in the manner described in the preceding paragraph, except that the polar solvent need not be removed. Finally the acid of the desired salt in an amount equivalent to the added metal oxide or hydroxide is introduced and all or a part of the polar solvent, then removed by heating to a temperature within the range of about 200 F. to 600 F. Additional mineral oil can be added at any or all stages of the compounding as will be obvious to one skilled in the art.

As a special case of the preferred method described in the preceding paragraph, the desired saponifiable material can be reacted with an amount of a basically reacting metal compound such as a metal oxide or hydroxide equal to that required to react with the saponifiable material and with the acid whose salt is desired in the complex. After the saponification has been completed the acid of the desired metal salt can be added in quantity just suflicient to neutralize the excess metal oxide or hydroxide present. It is also possible under this special case to mix the desired saponifiable material with the acid whose metal salt is desired in the complex and then add an amount of metal oxide or hydroxide or other basically reacting metal compound sufliclent to finally effect the saponification, form the salt and produce the complex. If it is desired to produce a final product having afree alkali or free acid content the desired acidity or alkalinity can be introduced at any of several stages as will be obvious to one skilled in the art.

Another preferred method of forming the metal soap complex lubricant is to dissolve a normal metal soap in mineral oil, add to the soap-oil solution a quantity of basically reacting compound and adding to this mixture an amount of a low molecular weight carboxylic acid suflicient to neutralize a portion of the basically reacting metal compound and finally contacting the resulting mixture with carbon dioxide to neutralize the remaining basicallyreacting compound. A modification of this method is to mix mineral oil, normal metal soap, metal salt of low molecular weight carboxylic acids, saponification reagent and water, and contact the mixture with carbon dioxide until the product is substantially neutral. The neutral product may then be dehydrated.

Still another preferred method of forming a metal soap complex lubricant is to dissolve a normal metal soap in mineral oil or to form the normal soap from the desired saponifiable material and basically reacting metal compound in the presence of all or a part of the desired mineral oil and add to this solution of soap in oil a quantity of basically reacting metal compound equivalent to the amount of salt which it is desired to complex with the normal metal soap. The resulting mixture, which will preferably contain the herein described amounts of polar solvent, is then blown with carbon dioxide gas to convert the free basically reacting metal compound to the corresponding metal carbonate. The resulting substantially neutral product may then be heated with stirring to evaporate the polar solvent and dehydrate the grease. This method may be modified by partially neutralizing the added free basically reacting metal compound with a low molecular weight carboxylic acid and converting the remaining saponification reagent into the carbonate by blowing the mass with carbon dioxide. The batch may then be lubricants of this inventlon'comprises oxidizing a mixture of normal metal soap and excess free basically reacting metal compound by blowing the mixture with a gas containing free oxygen in the presence of a polar ,solvent at temperatures between about 300 F. and 550 F. to produce acidic oxidation products in quantities sufilcient to partially neutralize the excess basic metal compound producing salts of the acidic oxidation products and then neutralizing the remaining basic metal compound by blowingthe oxidized mixture with carbon dioxide to form carbonates of the remaining free basic metal compound and dispersing the resulting substantially neutral product in mineral oil. In the above method in place of neutralizing the remaining free basic metal compound with carbon dioxide it may be neutralized with a low molecular weight carboxylic acid. Moreover, in either of these two latter processes the oxidation step may be effected in the presence of all or a part of the mineral oil required in the final product and in such cases the neutralized product may be dehydrated directly or the remainder of the required mineral oil may be added prior to or during the dehydration.

It is of particular interest to note that the greases constituting the subject of this invention can usually be produced as substantially anhydrous products having a stable grease structure. However, under some conditions and in order to obtain certain specific characteristics it may be desirable to produce greases containing small amounts of water, for example, less than about 1.0% and preferably less than about 0.5%. It will be obvious to one skilled in the art that this amount of water can be incorporated at any of several stages in the process of making the grease. For example, if the grease has less than the desired amount of water, the required additional Water can be added and worked into the grease at a temperature of 200 F. or less prior to drawing. On the other hand, if desired, an excess of water can be added to the grease before or after all of the oil has been incorporated or even during addition of oil and when the temperature is in the neighborhood of 210 F. or less or even at more elevated temperatures such as 220 F. to 300 F. and the excess water subsequently removed by increasing the temperature of the grease if necessary and then cooling after the desired water content has been reached.

The formation of the metal soap complex greases of this invention generally requires high temperatures, preferably in the region of about 400 F. to 550 F., although they can be formed over a wider temperature range such as about 300 F. to 600 F. In forming normal metal soaps, or in forming the metal soap complexes, the base sence of mineral oil.

may be added as a powder, in a granular form in water solution, or as an oil slurry as desired depending upon the character of the basically reacting metal compound employed. The soap or soap complex'iormation ispreferably carried out in the presence of at least a part of the mineral oil to be used in the finished lubricant, although it is sometimes desirable to carry out the saponification and/or oxidation reactions in the ab- In such cases the soap or soap complexes may be dissolved or dispersed in the mineral oil. In place of mineral oil, low boiling solvents may be employed under presgines; especially Diesel engines.

11 sure, the solvents subsequently being evaporated to leave a pure soap or soap complex residue.

The amount of metal soap complex to be incorporated in mineral oil to prepare desirable greases may be in the range of about to about 50%, althoughconcentrations as low as about 2% and as high as about 75% may be desirable for certain special combinations and applications.

The metal-soap complexes of this invention may also be used in relatively small proportions to produce liquid greases and fluid lubricants, such as, lubricating oil for internal combustion encentrations in such applications are usually below about 5% and are normally in the range'of 0.2% to about 2.0%. However by a proper choice of saponiflable material, metal salt, and mineral oil, it is possible to produce a fluid lubricant containing as high as by weight of metalsoap complex or even higher.

Materials other than metal soap complexes may also be added to the lubricating compositions of this invention, such as water, alcohols, and other solvents, antioxidants, flllers, etc'., as desired. An especially hard grease, for example, was prepared by the incorporation of an oil containing about 40% of asphalt instead of the usual lubricating oil to yield a satisfactory grease composition; Additions of petrolatum and solvent extracts from lubricating oil stocks have been helpful in some instances.

In addition to using both light and heavy mineral lubricating oils to make metal soap complex lubricants, I may also employ the light lubricating-type oil which is recovered as heavy bottoms from the distillation of residuals obtained in modern alkylation processes employed in making alkylated motor fuels from some stocks. In some such processes the mentioned residuals are recovered in fairly large proportions. About 80% thereof is then distilled off to be used for various purposes, thereby leaving about 20% of the heavy alkylated bottoms mentioned. This 20% fraction may be further cut to yield lighter and heavier fractions. These fractions have viscosities in the order of that of spray oil and of very The soap con-" light lubricating oil, e. g., SAE 10. In view of the properties of the metal soap complexes hereof, such heavy alkylated bottoms may be used as the lubricating fraction, especially where a light oil is desirable for a given fluid or greaselike product having a low pour point. The described bottoms may, for example, be recovered from the sulfuric acid alkylation process described in the "Refiner for September, 1941, 'vol. 20, page 378. Suitable bottoms are obtained, for example, after recovery of the motor fuel alkylate. Some stocks yield larger amounts of such alkylate bottomsthan others. These bottoms may in turn be fractionated for the present pur IJOSB.

The lubricants of this invention which comprise mineral oil containing metal soap complexes may be prepared using a single metal such as any of the metals mentionedin connection with the '12 lubricant. similarly, a normal soap of one metal may be combined with a low molecular weight carboxylic salt of a second metal and the. car- I bonate of a third metal to produce the finished lubricant. Moreover, in those instances in which the lubricants are prepared by contacting mixtures of saponifiable material and saponification reagent with oxygen, the saponification reagent may consist of a mixture of basically reacting metal compounds of two or more different metals.

Although the greases of this invention are generally stable and for most uses do not require the addition of antioxidants it is within the scope of the invention to include in the grease composition materials which tend to improve the oxidation resistance of the grease. Thus I may in,-

corporate small proportions, in the range of about 0.05% to about 1.5% and preferably between about 0.1% and 1.0% of antioxidants. Antioxidants which have been shown to have particular merit include amino compounds, such as phenylalpha-naphthylamine, phenyl beta naphthylamine, benzidine and tetramethyldiaminodiphenylmethane. As an example of the value of antioxidants in my greases, a sample of grease in which the thickening agent, amounting to about 28% by weight of the grease, comprised a normal barium soap-barium acetate-barium carbonate complex was tested alone and after the incorporation of 0.3% by weight of phenyl-betanaphthylamine for resistance to oxidation. The tests were carried out in a Norma-Hofiman oxidation bomb having a capacity of 180 cc. using 20 gram samples of the greaseaccording to the method described in the Proceedings of the Forty- First Annual Meeting of the American Society for Testing Materials, Part E, Technical Papers, pages 536-537. With an initial oxygen pressure of pounds per square inch and at a temperature of 210 F. the inhibited grease absorbed Example I Thefollowing ingredients were charged to a small, conventional-type, Steam-jacketed grease kettle equipped with an agitator:

, Pounds Tallow fatty acids 50.0 Glycerol 5.0 Calcium oxide 9.5 Water 50.0

The proportion of calcium oxide in the above charge represents 1.9 equivalents of base per equivalent of tallow fatty acids. In order to effeet the saponification of the fatty acids by the lime and partially dehydrate the product, the

350 F. Under these conditions the free calcium hydroxide content decreased to a value of 0.1%

by weight and the water content to a value of 0.1% by weight. The oxidized mixture was cooled to room temperature and again powdered. The

resultant product was a finished calcium soap.

complex concentrate.

Approximately 20 parts by weight of the above described calcium soap complex concentrate was charged to a steam-jacketed grease kettle equipped with an agitator and 80 parts by weight of oil of the following characteristics was added:

Color, NPA'. 4 Viscosity, Sayboit Univ. sec. at 100 F 600 Viscosity index 25 While mixing the kettle contents, the temperature was increased to 400 F. and as a result a uniform dispersion of the soap complex in the oil was obtained. This mixture was subsequently cooled to room temperature and cold-worked in the kettle to produce a stable anhydrous calcium grease having the following characteristics:

17.0 Nil A sample of the above grease when placed on a hot plate at 310 F. softened to some extent but maintained a characteristic body, did not gel and showed no tendency for the soap and oil to separate. Another sample of the same grease after standing at room temperature for three months showed no bleeding of oil, thereby demonstrating that this anhydrous calcium soap grease is stable.

Example II The followingingredients were employed for the preparation of a conventional type calcium soap grease using a procedure familiar to those skilled in the art:

' Pounds Prime tallow 171.0 Hydrated lime 26.0 Lubricating oil 764.0 Water 18.0

The lubricating oil employed in the above preparation was similar in characteristics to the oil described under Example I. The quantity of lime amounted to approximately 1.0 equivalent per equivalent of tallow.

The resultant grease had the following characteristics:

Calcium soap content, per cent by weight 18.0

Free fat, per cent by weight 0.4 Free base, calculated as calcium hydroxide,

' per cent by weight Trace Water, per cent by weight 1.8 A. S. T. M. penetration at 77 F 235 A. S. T. M. dropping point, F. 210 Appearance An opaque grease of smooth texture and light yellow color.

The above product is a typical cup grease. A sample of this grease placed on a hot plate at 310 F. rapidly melted to a clear liquid having no grease body even though it has approximately the same soap content as the product described in Example I.

14 Example III The following ingredients were charged to a steam-jacketed kettle equipped with an agitator:

Pounds Prime tallow 200.0 Sodium hydroxide, 50% solution 100.0 Pennsylvania 600 S. R. oil 200.0

The proportion of sodium hydroxide added represents 1.8 equivalents of base per equivalent of tallow. The above ingredients were mixed and heated to a temperature of 275 F. in order to efiect saponification and partial dehydration. Subsequently, the temperature was increased to 450 F. to 500 F. and maintained in this range for four hours while continuously circulating air over the kettle contents. Under these conditions the free alkali content decreased from 4.85% to 1.07%. Approximately 75 parts by weight of the saponifled and oxidized product was subsequently compounded with 125 parts of oil, similar in character to that described in Example I, at a temperature of 325 F. The material was then cooled to room temperature and cold-worked yielding a grease having the following characteristics:

Soap content, per cent by weight 20.0 Free base, calculated as sodium hydroxide,

per cent by weight 0.4 A. S. T. M. penetration at 77 F 248 A. S.'T. M. dropping point, F. 400+ This grease had a smooth non-fibrous texture and a translucent appearance. When placed on a hot plate at 310F. it maintained a characteristic grease body and showed no tendency to separate. Another sample of the finished grease which was permitted to stand for six months at room temperature showed no oil separation.

Erample IV A strontium grease produced in accordance with the present invention was prepared from the following ingredients:

Kilograms Prime tallow 30.0 Strontium hydrate 26.5

Pennsylvania 600 S. R. oil 139.7

35 kilograms of oil was added to the kettle and the temperature subsequently increased to 500 F. with continued agitation. Air was circulated over the kettle contents and the temperature maintained at 500 F. until analysis indicated that the quantity of free base had decreased to 0.4% by weight. Heating was then discontinued and the'remaining oil added slowly in order to maintain a homogeneous system. During this stage additional cooling is desirable in order to maintain as heavy a grease body as the equipment will handle. Circulation of the grease through a gear pump and a perforated plate is also helpful. After all of the oil had been added and the grease cooled to 200 F., 1.5% by weight of water was added to the kettle while continuing to mix the grease with the paddle agitator and circulating with gear pump through istics of the finished grease were as follows:

Soap content, per cent by weight 21.6 Free base, calculated as strontium hydroxide, per cent by weight 0.48 A. S. T. M. penetration at 77 F. .330 A. S. T. M. dropping point, F. 400+ This grease had a smooh buttery texture and maintained a characteristic grease structure when heated to 310 F. on'a hot plate. A sample which was stored at room temperature for six months showed no separation of oil.

Example V A mixed-metal grease was prepared from the following ingredients:

Pounds Prime tallow 200.0 Strontium hydrate 97.0 Lithium hydrate 23.6

Pennsylvania 600 S. R. oil -1- 20.0.0

The quantities of strontium hydrate and lithium hydrate represent one equivalent and 0.8 equivalents of base per equivalent of fat, respectively. 7

The above materials were charged to a kettle and heated to 212 F. to effect saponiflcation and partial dehydration. Subsequently, while circulating air in contact with the kettle contents the temperature was increased to 400-450 F. and maintained in this range until the free alkali content, calculated as strontium hydroxide, had decreased to a value of 0.2%. This operation required about ten hours. Subsequently, 50 parts by weight of this concentrate was compounded with 50 parts by weight of 600 S. R. oil thereby yielding a grease having the following characteristics:

Soap content, per cent by weight 26.0 Free alkali, calculated as strontium hydroxide, per cent by weight 0.14 A. S. T. M. dropping point, F. 370

A. S. T. M. penetration at 77 F 280 This grease had a smooth buttery texture and showed no tendency for separation of soap and oil.

Example VI By the methods of this invention an unusually stable lithium soap complex grease was prepared from the following ingredients:

Pounds Prime tallow 145.0 Lithium hydrate 30.0 Oil 100.0

While agitating the kettle contents in contact- 7 with air, the temperature was increased to 400- 550 F. and maintained in this range for a period 16 of five hours. cooled to about 300 F., compounded with an additional 400 parts by weight of oil, and then further cooled to F. The material was finally cold-Worked and drawn into packages. The resulting grease had the following characteristics:

Soap content, percent by welght 24.0 Free alkali, calculated as lithium hydroxide, percent by weight---" 0.4 A.-S. T. M. penetration at 77 F A. S. T. M. dropping point, F 377 The greasehad a smooth buttery texture and showed no tendency toseparate oil even after standing for prolonged periods of time.

' Example VII A lithium soap complex grease was prepared from the following ingredients: I

Grams Stearic acid Sperm oil Lithium monohydrate-u Waxy gas oi The stearic acid, sperm oil and 5000 grams of I the gas oil were mixed in an open steam-jacketed kettle equipped with an agitator, a slurry of lithium hydrate with 1060 grams of the gas oil was added and the mixture subsequently heated to a temperature of 300 F. to effect saponiflcation. After saponification had been completed the material was cooled to a temperature of 200 F. and 780 grams of acetic acid, slightly more than that required to neutralize the free lithium hydroxidebodied up when heated to 200 F.300 F. and yet when it was cooled to room temperature the grease returned to a soft unctuous consistency. The following A. S. T. M, penetrationvalues show the characteristics of this material.

A. S. T. M. penetration at 77 F -870 A S. T. M. penetration at 250 F 280 A. S. T. M. penetration at 77 F 360 (Cooled material from a previous test.) The following is the calculated composition of the finished grease:

Lithium sperm oil soap, percent by weight 14.2 Lithium stearate, percent by weight 3.5 Lithium acetate, percent by weight 2.7 Free acid, calculated as acetic acid 0.1

Waxy gas oil and unsaponifiable materia1 79.5

Example VIII A calcium soap complex grease was prepared from the following ingredients:

Subsequently, the material was Grams The acetic acid was added to a mixture of the hydrated lime and 100 grams of the lubricating oil and the mixture was heated to 200 F. The prime tallow was added to the product and the heating continued until saponiiicatlon of the tallow was substantially complete, The saponified product was heated to 300 F. and carbon dioxide was then blown through the mixture to neutralize the remaining hydrated lime. The remaining 315 grams of lubricating oil was added slowly to the neutral mixture while continuing the agitation. With the grease at a temperature of 300 F., 20 grams of water was added and the heating and mixing continued until the product was substantially anhydrous. The product was a smooth unctuous transparent grease with an A, S. T. M. penetration of 100 at 77 F.

Example IX A calcium soap complex grease was prepared in a manner similar to that described in Example VIII, except that glycolic acid was employed in place of the acetic acid. The resulting grease was similar in appearance to the product of Example VIlI although it had a somewhat greater consistency.

Example X Example XI A barium soap complex grease was prepared according to the method outlined in ExampleVIII for the calcium grease except that an equivalent amount of barium hydrate was used in place of the hydrated lime and an equivalent amount of propionic acid was used in place of half of the acetic acid. The finished grease contained approximately 0.25 equivalents of barium acetate, 0.25 equivalents of barium propionate and 0.5 equivalents of barium carbonate per equivalent of normal barium soap. The product was a smooth unctuous grease having an A. S. T. M. penetration of 150 at 77 F.

The foregoing description and examples are not to be taken as in any way limiting but merely illustrative of my-invention for many variations may be made by those skilled in the art without departing from the spirit or scope of the following claims.

I claim:

1. In the process of producing a lubricant the steps of reacting 1.0 equivalent of a saponifiable material with more than 1.1 equivalents'of a basic metal compound in order to effect saponification of the saponifiable material, subsequently increasing the temperature and contacting the reacting mass with oxygen in order to cause a partial oxidation of the soap present, and finally adding mineral oil.

2. A method of producing a lubricating composition comprising oxidizing a metal soap with a gas containing free oxygen in the presence of at least 0.1 equivalent of free basic metal compound per equivalent of metal soap and in the presence of a polar solvent until the product is 18 substantially neutral and mixing the substantially neutral product with mineral oil.

3. A method of producing a lubricating composition according to claim 2 in which said basic metal compound is a compound of a metal of group II of the periodic table.

4. A method of producing a lubricating composition according to claim 2 in which said basic metal compound is a compound of a metal of the iron group of group VIII of the periodic table.

5. A method or producing a lubricating composition according to claim 2 in which said basic metal compound is a compound or an alkali metal.

6. A method of producing a lubricating composition comprising oxidizing a metal soap with a gas containing free oxygen in the presence of at least 0.1 equivalent of free saponiilcation reagent per equivalent of metal soap and in the presence of a polar solvent to form acidic oxidation products in quantities suflicient to substantially completely neutralize said free saponification reagent thereby producing a. mixture comprising metal soap and salts of said acidic oxidation products and dispersing said mixture com prising metal soap and salts of acidic oxidation products in mineral oil.

7. A method of producing a lubricating composition comprising oxidizing a metal soap with a gas containingfree oxygen in the presence of at least 0.1 equivalent of free basic metal compound per equivalent of metal soap and in the presence of a polar solvent to produce acidic oxidation products in quantities sufllcient to partially neutralize said free basic metal compound thereby producing salts of said acidic oxidation products, neutralizing the remaining free basic metal compound by contacting the oxidized mixture with carbon dioxide, thereby forming carbonates of the remaining tree basic metal compound and dispersing the resulting substantially neutral product in mineral oil.

8. A method of producing a lubricating composition comprising contacting a mixture of mineral oil, metal soap and free basically reacting metal compound with carbon dioxide until the product is substantially neutral to form a metal soap complex.

9. A method of producing a lubricating com- 50 position comprising mixing mineral oil, metal soap and basically reacting metal compound, adding thereto an amount 01. a low molecular weight carboxylic acid suflicient to neutralize a portion of said basically reacting metal compound and 55 contacting the resulting mixture with carbon dioxide to neutralize the remaining basically reacting compound to form a metal soap complex.

10. A method of producing a lubricating composition comprising mixing mineral oil, metal 50 soap, metal salt of low molecular weight carboxylic acid, saponification reagent and water, contacting the mixture with carbon dioxide until the product is substantially neutral to form a metal soap complex, and dehydrating the sub- 05 stantially neutral product.

11. A method of producing a lubricating composition comprising saponifying one equivalent of a saponifiable material with more than 1.1 equivalents of a basically reacting metal compound, 70 contacting the saponified mixture with carbon dioxide until the mixture is substantially neutral to form a metal'soap complex and subsequently dispersing the substantially neutral mixture in mineral oil.

12. A method of producing a lubricating composition comprising oxidizing a metal soap with a gas containing free oxygen in the presence of v at least 0.1 equivalent of free basic meta1 com-' pound per equivalent of metal soap and in the presence of a polar solvent to produce acidic oxidation products in quantities sufllcient to partially neutralize said free basic metal compound thereby producing salts of said acidic oxidation products, neutralizing the remaining free basic metal compound with a low molecular weight carboxylic acid thereby forming carboxylic acid salts of the remaining free basic metal compound and dispersing the resulting substantially neutral product in mineral oil.-

13. A method of producing lubricating grease which comprises oxidizing an alkali metal soap in the presence of at least 0.1 equivalents of basic-metal compound per equivalent, of alkali metal soap at a temperature substantially between 300 F. and 550 F. with a gas containing free oxygen and subsequently adding mineral oil to said oxidized soap.

14. A method of producing a lubricating composition comprising contacting a mixture of mineral oil, normal alkali metal soap and free basically reacting alkali metal compound with a low molecular weight carboxylic acid at temperatures of from 300 to 600 F. until the product is substantially neutral to form a metal soap complex containing normal alkali metal soap and alkali metal salt of low molecular weight carboxylic acid dispersed in said oil.

15. A method of producing a lubricating composition comprising mixing mineral oil, normal alkali metal soap and alkali metal salt of low molecular weight carboxylic acid in the presence of water at temperatures of from 300 to 600 F. to produce a substantially neutral product of an alkali metal soap complex containing normal alkali metal soap and alkali metal salt of low molecular weight carboxylic acid dispersed in said oil, and dehydrating the substantially neutral product.

16. The method as set forth in claim 10, in which the metal of the soap and of the salt is an alkali metal and the saponification reagent is a basically reacting alkali metal compound.

LESTER. W. McLENNAN.