US2012252A

US2012252A - Grease

Info

Publication number: US2012252A
Application number: US567527A
Authority: US
Inventors: Arthur W Burwell
Original assignee: Alox Corp
Current assignee: Alox Corp
Priority date: 1920-11-12
Filing date: 1931-10-07
Publication date: 1935-08-20
Anticipated expiration: 1952-08-20

Description

a soap,

Patented Aug. 20, 1.935

UNITED STAT-ES GREASE Arthur W. Burwell, Niagara Falls, N. Y., assignor to Alox Corporation, New York, N. Y., a corporation of New York No Drawing. Application October '1, 1931,

Serial No. 567,527 r l 8 Claims. (01. 81- 9) This invention relates to lubricating greases and to a process for preparing the same.

By the expression lubricating grease is meant a semi-solid lubricant comprising a mixture of such for instance as a calcium soap ora sodium soap made from tallow, and a lubricating oil, such for instance as a mineral oil of medium viscosity, which mixture may or may not be an emulsion. According to their constitutions and uses, they are, known variously as cup greases", driving journal compounds, fiber greases, gear greases, axle greases, and by many other names.

Typical of such lubricating greases, and of the methods commonly employed in their manufacture, is the following:

To about 90 pounds of stearic acid (single pressed), or to an equivalent amount of good stearine or tallow, in a steam-jacketed kettle provided with a stirrer, is added nearly a like quantity, say 100 pounds, of steam-refined cylinder stock, and the resulting mixture is agitated until a homogeneous mixture results. To this homogeneous mixture there is then added suflicient caustic soda solution (say, 50% solution) to saponify all the saponifiable constituents thereof, and the mixture is then heated, with constant stirring, until not more than about 1% of water remains in the mass. The progress of the reaction is indicated by the evolution of steam, and the heating temperature is so regulated that the reaction mixture does not boilv over. The resulting extremely viscous, sometimes crumbly, mixture is then withdrawn into suitable containers in which it, upon cooling, solidifies. This product, a so-called driving ioumal compound", has a dark brown to black color, and a fibrous fracture, is sticky and harsh to the touch, and

may be "worked between the fingers to a rather stifibut slightly spongy mass. It begins to flow readily at about 475 to 500 F.; at temperatures substantially below this flow point it does not readily yield lubricant films. In use, a cake of the material is placed in the "cellar of a locomotive driving journal upon a spring-actuated feeding device which forces the cake against and through a perforated plate or coarse screen (e. g., one having openings from A; to inch) which plate or screen is immediately under the bearing surface of the journal.

Lubricating greases similar to the above-described have various disadvantages, aside from that just noted, including chiefly a tendency to leak or give up their contents of lubricating oil more readily than their contents of soap, with unctious rather the result that the partially used cake or mass has a too-high soap content and an unduly high melting point so that the journal itself must be heated to still higher temperatures before the mass will feed properly and form an interface.

It 'is the common practice to evaluate such greases on the basis of the relative value of their lubricating oil constituents, as it is commonly understood that the lubricating value of the grease is dependent mainly upon the oil therein: consequently in well made greases only high grade lubricating oil stocks commonly are employed.

I have found that the above, and other disadvantages may be .overcome, and that a very material economy may be secured, by preparing lubricating greases from lubricating oils and soaps of certain acidic mixtures obtained by the partial, liquid-phase, oxidation of hydrocarbons of mineral origin. The'lubricating greases, embodying the present invention readily give off lubricant films at temperatures materially below their flow points; do not leal-r" their lubricating oil contents but persist as constant com-- positions; and are further characterized by an than a sticky .feel, slipperiness, a conchoidal fracture, and a rubbery as opposed to fibrous structure.

As starting material for the preparation of the soaps employed in preparing my greases I use acidic mixtures, consisting essentially of relatively high-molecular-weight carboxylic acids soluble in petroleum hydrocarbons but insoluble in water, which acidic mixtures are found in and may or may not be separated from reaction mixtures from the' partial oxidation of such hydrocarbon mixtures as 36-40" Baum petroleum distillate,'45 Baum petroleum distillate, and other mineral hydrocarbons, including parafin wax, but especially the semi-solid product, known variously as dark green petrolatum, Sharples wax, or amorphous wax, which is obtainable from crude petroleum oil by diluting the topped crude with a relatively large amount of gasoline,

chilling the 'mixture to say to 40 below zero F., and centrifuging liquids from the so-chilled mass.

Thus, the starting material for the preparation of these soaps may be the whole mass, resulting from the protracted oxidation of paramn wax,

or it may be an acidic mixture separated from solution described in Method I above, is treated a saponification value of from about 110 to about 1'75 or an acidic mixture separable therefrom or it may be an acidic mixture separable from the reaction mixture from the partial oxidation of one or another of the other mineral hydrocarbons referred to above.

The process of oxidation, which forms no part of the present invention, and the compositions of the resulting reaction mixtures, are fully described in my U. S. Patent No. 1,768,523. These reaction mixtures consist essentially of the aforesaid petroleum-soluble high-molecular-weight saturated aliphatic carboxylic acids, unsaponiflable but readily emulsifiable oxygen-compounds of hydrocarbons including compounds of alcoholic and/or ketonic constitutiomand unoxidized hydrocarbons, all in varying amounts. Preferably I oxidize under such conditions and for such a period of time that the reaction mixture has a saponification equivalent of from about 110 or 120 to about 1'75.

From the aforesaid reaction mixtures I may, and preferably do, separate a product rich in, or substantially consisting of, the said aliphatic carboxylic acids by one of a number of operable methods including the following preferred methods:

I. Saponiflcation method To the reaction mixture is added sufficient saponifying agent, e. g., caustic soda solution, to saponify all of the saponiflable constituents thereof, the resulting soapy solution is separated from oily, unsaponified and non-emulsified components of the mixture, and the soapy solution is treated with an amount of an acid, e. g., sulphuric acid, sufficient to'decompose or break" the soaps precipitating the water-insoluble organic compounds thereby released, and separating the precipitated organic compounds from the aqueous solution; The organic compounds which constitute the separated mixture consist essentially of the aforesaid high-molecular-weight aliphatic carboxylic acids together with a material amount ofunsaponifiable, non-acidic, oxidized hydrocarbons which readily emulsify with the aforesaid soaps and persistently associate with them.

II. Alcoholic separation method The aforesaid reaction mixture, or the soapy with alcohol (e. g., to ethyl alcohol of constituents thereof, the alcoholic solution is.

separated from the constituents insoluble in alcohol, and the solvent is removed (as by distillation) from the so-separated compounds. By this method a resulting product is obtainedwhich is considerably richer-in, or consists substantially of, the aforesaid acids.

By whichever of the above methods produced, the product rich in the aforesaid acids may readily be saponified by treatment with an appropriate amount, that is, the theoretical amount, of an alkaline saponifying agent such as caustic soda to neutralize the acidic constituents thereof, whereby to produce soaps (or neutral products consisting largely or essentially of soaps) of theacids, which soap mixture, or soapy mixture, is freely soluble in or miscible with the commonly known and used lubricating oils or their equivalents to the production of lubricating greases having the desirable properties hereinbefore de: scribed. 7

Illustrative of the manner in which the greases forming the basis of the present invention are prepared is the following:

Example I steam-refined lubricating oil stock (10 pounds),

and the dehydrated mixture is saponified by treatment with 14.4 pounds of a 50% caustic soda solution, either at room temperature or at an elevated temperature of the order of 200 F., with thorough stirring. To the dehydrated mixture there is then added, with agitation and while the mixture is maintained at a temperature above about 220 R, an amount of the lubricating oil stock sufficient to bring the total content of lubricating oil to the proportion desired, say 40 pounds. I may, and preferably do, subject the mixture to a milling treatment or its equivalent to smooth out any lumps or granules in the grease product. The resulting composition is then drawn off into suitable molds or other containers and there solidified by cooling.

The above-described dehydration step is not essential and, of course, is not practiced in the case where the acidic starting material contains practically no water.

The. lubricating grease so produced is a driving journal compound having a melting point of about 540 F. but begins to deform at about 460-475" F.: it is much more unctious to the touch than a sodium stearate grease, is not sticky, and does not leak its lubricating oil constituent either in storage or under the conditions of use, breaks (cold) with a conchoidal fracture, and is slippery to the touch. .From the standpoint of economy, it may be prepared at an actual cost materially below that of the commonly used sodium stearate grease.

The foregoing specific example may be modified by the substitution of an acidic mixture separated from the reaction mixture produced by the oxidation of paraifin wax or of one or another of the various distillates of petroleum, or by the substitution of the acidic reaction mixtures as such, for the acidic mixture there specifically disclosed. As was indicated in the foregoing general description of the invention, I may subject the oxidized masses, as such, to saponification treatment, whereby to transform into soaps their whole content of saponiflable constituents, there by producing a soapy product consisting of, on r oil, in the manner described in the foregoing specific example, to the production of greases.

The relative consistency or hardness of the greases forming the basis of the present invention may be modified in any one of several ways:

scribed. Thus, there may be made in substantially the same manner relatively softer greases,

having lower. melting and deforming points, in-.

cluding cup greases, roller bearing greases,

'- greases adapted for use in lubricating floating bushing bearings, and the like. Also, a relatively very hard grease may be prepared by combining with the soap described in Example I above a suitable amount, say 40%, of unoxidized dark. green petrolatum or Sharples wax". This latpetroleum lubricating oil of about 200 viscosity (at 100 C.) with the soap produced by treating with calcium hydroxide the acidic mixture obtained from oxidized parafllne wax. This latter is a transparent, light-colored, grease of excellent lubricating properties.

The grease from the calcium soaps oi the petroleum acids" are preparedln a manner similar to that commonly employed in the making of lime greases" from stearic acid or tallow, it being desirable, however, on account of the tendency of the calcium' hydroxide to seize the petroleum acids" to mix a small amount oi lubricating oil stock with the acids before adding the calcium hydroxide, and then to introduce the latter into the mixture as an emulsion of the cal? cium hydroxide in a further amount of the lubricating oil: after the soap is well dispersed the necessary further additions of lubricating oil may be made. This reaction preferably is conducted at a temperature below 212 F. and under vigorous agitation. The resulting products are remarkably unctious, of short shear, and of a more or less buttery consistency.

Example H A leaded transmission grease" may be prepared by the following method:

The oxidation reaction mixtureohtained from Sharples wax is saponified in the manner set out in Example ll above, the soap solution isseparated from unsaponiflable constituents or the reaction mixture and is largely diluted with water whereby to precipitate emulsified but unsaponified bodies persisting with the soap solution, and the resulting purified soap solution is treated with an appropriate amount of a lead salt, such, for instance, as lead nitrate, in aqueous solution. Thereby there is precipitated a mixture of lead soaps of the acids, which mixture may be dehydrated inknown manner. at about 245 to 265 F. These lead soaps are admixed without difficulty, in the warm, with a lubricating oil stock, producing what apparently is a true solution of the lead soaps in the oil.

Instead of the above method, these lead soaps may be prepared by treating the separated acidic mixtures with lead carbonate or an equivalent lead salt, or, with less facility, even litharge. In the last-mentioned case, it is difllcult to dissolve or suspend suflicient litharge in the acidic mixture to obtain as high a lead content in the resulting soap as is possible when practicing the --double-decomposition method above described.

My researches with other metallic soaps of these "petroleum acids" has demonstrated that the soaps of iron, aluminum, manganese and other metals all are either soluble, or at least distensible, in lubricating oils whereby to make lubricating greases. Furthermore, soda-lime greases, and other so-called mixed greases and "sett greases have been made in accordance with this process.

By the expression a salt of. a petroleum acid' as used in the appended claims I mean to include not only a" single salt of a single isolated petroleum acid but also either salts of a plurality oi'petro- By petroleum acid" as used in the appended claims I mean a relatively high-molecular weight, saturated, aliphatic, carboxylic acid soluble in petroleum but insoluble in water, which acid was derived from an aliphatic hydrocarbon of mineral origin by controlled liquid-phase partial oxidation of the latter. See the disclosures in U. S. Patents 1,828,356, 1,863,004 and 1,770,876.

I claim:

1. Process which comprises treating with a saponifying agent a relatively high molecular weight saturated aliphatic petroleum acid derived from a reaction mixture obtained by the controlled partial oxidationloi a mixture of aliphatic petroleum hydrocarbons and incorporating in the resulting soap -a petroleum lubricating oil in an amount substantially greater than that of the soap but restricted to the production of a product which is solid-to semi-solid at normal room temperature. I

2. A lubricating grease composition consisting essentially of from about 35 to about 50% by weight of a hydrocarbon mixture of mineral origin and having lubricating properties containing dissolved therein from about 65 to about 50% by weight of oil-soluble salts of a mixture of relatively high molecular weight saturated aliphatic carboxylic acids derived from an aliphatic hydrocarbon mixture oi mineral origin bycontrolled liquid-phase partial oxidation of the latter, said composition being a solid grease.

3. As a new product, a lubricating grease con-' sisting essentially of a substantially anhydrous solution 01' a soap the acid radical of which is a saturated aliphatic carboxylic petroleum acid derived from a reaction mixture obtained by the controlled liquid phase partial oxidation of a mixture of aliphatic petroleum hydrocarbons and the basic radical of which is a metallic element or the group consisting of sodium, potassium, calcium, iron, aluminum, manganese and lead in a substantially anhydrous medium consisting of a mineral lubricating oil, which grease is semisolid to solid at normal room temperature.

- 4. The product defined in claim 3 characterized in that the basic radical is sodium.

5. The product defined in claim 3 characterized in that the basic radical is calcium.

petroleum hydrocarbons rich in petroleum acids.

6. The product defined in claim 3 characterized oxidation of ,a mixture of aliphatic petroleum hydrocarbons with a reactive compound of a metal oi the group consisting of sodium, potassium, calmixture obtained by the controlled liquid-phase cium, iron, aluminum, manganese and lead, partial oxidation of a mixture of aliphatic pewhereby a salt of said metal and said acid is troleum hydrocarbons with an alkaline saponifyproduced and dispersing the so-iormed salt in a ing agent in an amount to neutralize the said acid petroleum lubricating oil in such relative proporwith formation of a soap therefrom, and dissolv- 5 tions as to yield a product which is solid to semiing the so-formed soap in a petroleum lubricating solid at normal room temperature. oil in such relative proportions as to yield a prod- 8. Process which comprises reacting a dehyuct which is solid to semi-solid at normal room drated sodium soap of a saturated aliphatic cartemperature.

i boxylic petroleum acid derived from a reaction ARTHUR W. BURWEIL. 10-