US 2151641 A
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. one solution. Usually,
Patented Mar. 21, 1939 UNITED STATE GREASE Bass AND METHOD or MAKING Latimer D. Myers, Cincinnati, Ohio, asslgnor to Emery Industries, Inc., Cincinnati, Ohio, a corporation or Ohio.
No Drawing. Application December 21, 1936, Serial No. 116,996
9' Claims. (olfs'z-s v This invention relates to the preparation of bases particularly adapted to be used in the manufacture of lubricating greases. The invention comprehends a new series of grease bases, or substances adapted to use inthepreparation of greases from mineral oils, and comprehends also a new method by means of which these bases are prepared.
In the past it has been conventional to manufacture greases from mineral oil, soap and water. In the more or less conventional types of greases adapted to use for general lubricating purposes, the calcium soaps have been used quite extensively. Greases of this nature essentially comprise emulsions of oil and water in which the water isheldin the oil by the action of the soap.
More recently, it has been determined that the greases which are'in anhydrous condition possess qualities which are not possessed by the greases of the moisture variety. The greases which contain moisture essentially comprise emulsion of water in oil, in which the soap is present to maintain the emulsion in the established state. In these greases the tendency is for the emulsion to break and the oil to separate during periods of storage or long standing. The body and consistency of these greases permanently is lost if or when the greases are subjected to tempera-l I tures sufilciently high to drive off any substantial quantity ofthe water which is present.
The anhydrous greases on. the other hand are not dependent upon the presence of water for their stability, but to the contrary, the less water they contain, the more eiiiciently they seem to function. The primary objective of the present. invention has been to provides. series of bodies which are-dry and which are particularly adaptedtobeusedinmakinggreaseswhicharedry.
By reason of the fact that the presentinvention provides a series of anhydrous bases, comprised of metal soaps of fatty acids, which are very much superior to the soaps .which heretotore havebeen available and which possess the capacity to 'make better greases than thou which have been available, a brief analysis of. various methozh tor making the metallic soaps of fatty acids is'requisite to understanding of the'present advance. i
In the pastiit has been conventional to prepare the soaps used'for making greases '9! the calcium soap variety by the double decomposition of a watersoluble soap, for-example, a sodium soap with-a water soluble calcium salt,'in aquesolve in mineral oil at elevated temperature. 01
the other hand, at ordinary room 952,! have disclosed a process hydrous greases which are stable and which'are strong in lattice structure.- According to this pared in the ordinary manner, then these soaps are dissolved in water, and flnallythe calcium. salt (for example, calcium chloride) gradually is added to the solution to cause precipitation of insoluble calcium soap, which then is filtered off 5 or separated from the remaining liquid in any convenient manner. This soap next is washed free of inorganic salts and finally is dried. The process obviously is expensive; it requires extensive equipment; and a proportionately large 10 quantity of sodium chloride, which has little or no value, is left as a by-product or waste.,
Another method of preparing the calcium soaps of fatty acids involves the saponification of fats with lime. While this process in general is less 15 expensive than the method of double decomposi- 'tion, still, pressure is required during the saponifying procedure, the saponiflcation is relatively difiicult to conduct and still more diiiicult to complete and the final product is not in an an- 20 hydrous state.
Still another process for preparing calcium soaps of fatty acids is predicated on the fusion of fatty acids with lime. According to this procture. During the reaction, a heavy moltenfimass continues, and as the fatty acid content in the admixture is reduced, this mass becomes less molten and more viscous. Thorough stirring and mixing becomes diificult, and some of the material in the vessel sticks to-the sides of the container and "tends to become charred or otherwise badly discolored. The process as a whole is not well suited to commercial production methods.
The pure dry fatty acid soaps of calcium, zinc. magnesium; and the like can be made to distemperatures these same soaps are almost totally insoluble. If, solutions of the soaps temperature and-are allowed to cool and set to gels, the difliculty is that these gels are broken easily by stirring or other mechanical disruption, and, when. this occurs, the body lost and the soaps precipitate.
Inmy copending patent application Serial No.. for preparing an-' process an. auxiliary material is used which effects dissolution of the soap in the oil at ordinary. temperature. I have in this copendinsess, the fatty acids are melted and fusion with 25 the lime takes place at relatively high temper'aare madein oil at high of thegrease is tion of poly dric and dihydric alcohols. with higher fatty acids, are well suited to the purpose.
The grease bases of the present invention are anhydrous products which are characterized by their solubility in mineral'oil at relatively low temperature, next by the presence of a quota of a metallic soap of a fatty acid, and furthermore by the presence of a quota of a substance containing free hydroxyl groups adapted to eifect dissolution of the soapof the base in mineral oils at ordinary temperatures. The provision of bases for making greases which are thus characterized, and a tained "comprise the primary objectives of the invention. a
Briefly, the concept or the principle upon which the present invention is predicated resides in a process in which two reactions are caused to take place substantially conjointly. In the first of these reactions a quantity of metallic soap of fatty acid isformed by the fusion method but the quantity of fatty acid which is present during the fusion is-in excess of that required to make the soap; In the other reaction this excess or free quantity of fatty. acid is changed in situ to a fatty acid derivative which is soluble in mineral oil; which is relatively nonvolatile and which has a'solvent action or tendency in relation to the fatty acid soap.
According to my copenqing patent application previously identified, I have disclosed that typical compounds having free hydroxyl groups suitable for the purpose of eflecting dissolution of the calcium soap in the mineral oil under the conditions preferred, are the partial esters of fatty acids such as stearic, and the polyhydric or dihydric alcohols. These esters commonly are preparedby- 'heating to a relatively high temperature (around the fusion or reaction of a dry metal salt with fatty acid is-difllcult to conductbecause of the encountered in stirring and handling the mass which becomes more and more viscous as the reaction proceeds to completion. 1
Paradoxically, however, it is the concept of the present invention to combine two reactions, each slow and diillcult to conduct individually, and
' 1 provide a process for making the products desired.
' which is conducted with much more ease and with much greater convenience than in either process and which proceeds to completion much more rapidly. Thus, a conjoint reaction-is established,
* desired anhydrous condition of the base isaccomplished. v
In-the practice of the present inyentiomthe use of a quota of fatty acidin excess ofwthat required to produce the metallic soap has two-fold -In the first place, if the quantity of fatty acid is in the right amount to combine with thealkali tomakethe soap then as the reaction proceeds, the mixture becomes very difli cult to handle. The excess of fatty acid, however, in a same has the function of a diluentorgsolvent. Whenthisexcessispresentitthinsdownthemixies is representative of .which is specifie to the generic principlewhich and consequently the diiliculties in stirring and handling are obviated. 7
On the other hand the excess provides a quota of fatty acid from which to derive a substance which renders the metallic soap soluble in mineral oil and which also acts as a solvent for the metallic soaps with the result thatthe mix remains relatively fiuid at all stages of the operation. Thus, the process is characterized by two features. The consistency of the mass is relatively thin and workable even as the free fatty acid content is lowered by the formation of soap, and the agent for stabilizing the soap and eifecting its dissolution in mineral oil at room temperature is provided in the mass with ease and convenience. process by means of which these bases are ob- The present invention particularly is disclosed in relation to the formation of the partial esters of the polyhydric and dihydric alcohol and fatty acids as the bodies adapted particularly to effect the dissolution and stabilization of the metallic soap in mineral oil. The disclosure of these boda preferred embodiment is involved.
The following examples illustrate the procedure for making various grease bases in accordancewith the present invention:
Example 1Lime soap base in' which gluceryl' mono stearate is present- The optimum proportion of calcium stearate and glyceryl mono stearate for any given oil which is to be used forthe manufacture of a grease is determined empirically before hand, that isby making greases and determining the mixture which yields the most desirablej product.- The fatty acid, which preferably is stearic acid, is thenintroduced into a suitable container either direct-fired or steam-jacketed and heated to about C. Next, the requisite quantity of dry powdered lime is added slowly. Reaction occurs very readily and the mass remains fluid due to the presence of the excess of fatty acid.
The quantity of polyhydric alcohol required to combine-with the remaining fatty acid is added, mole for mole, preferably after a short period of time with continued heating, the temperature being raised to C. The reaction proceeds smoothly and th mass remains fluid as the hydr'oxy ester which is formed is also asolvent for the soap produced in the prior step. After about two hours the free fatty acid usually is less than 5% and the resulting product is poured into molds to solidify or may be poured over a flaking roll.
The peculiar thing which will be u the metallic soap which is formed seems to catalyze the reaction between'the excess of fatty acid and the alcohol. Ordinarily, it is' relatively difllcult to accomplish partial esteriflcation in a relatively reasonable time. Still, in the presence of the fatty acid spap esterlficationproceeds rela'-. tively rapidly. 'And as the excess of fatty acid is esterified the fluidity, or workability of the-mass as a whole does not change appreciably in view of the fact that the fatty acid esters at the reaction temperature themselves are in relatively fiuid isthat condition. This aspect of the invention is, .of
tion of the hydroxy ester when no calciumsoap l is present, particularly in view oftne fact. that v thetheoretical quantity, or only veryslightlyover higher fatty alcohol' time the fatty acid the theoretical quantity of is employed. At the same esters which are formed maintain the calcium soaps in fluid condition.
r Example 2-Preparation of a base consming of four parts calcium stearate and one part glyceryl mono stearatesomewhat during the last few minutes of the run.
This incorporates air in the product, which finally is moulded. The entrained air renders the product friable and easily powdered.
' Other proportions of calcium stearate and 25 glyceryl mono stearate are prepared by the use" of the proper amounts of lime and glycerine. A
ratio of six parts of calcium stearate to one part of glyceryl mono stearateis about the maximum which can be prepared conveniently as this mix- 30 ture contains about the minimum quantity of mono stearate which is capable of keeping the fused mass in a relatively fluid state.
In the practice -of the invention, it ispreferred to saponify the fatty acid with one of the usual 2 calcium salts, such as lime, in order toprovide the corresponding calciun'f soap. However, the process of the invention is adapted to use in the production of bases for making greases in which other soaps than the calcium soaps are used.
40 magnesium, zinc, ,lead cobalt and similar soaps of high titre fatty acids such as stearic or palmitic may be used as "substitutes for the calcium salts.
Other substances likewise can be used in place of the glycerine to react with the excess of fatty acid toprovide, fatty acid esters thereof mingled with fatty acid soap.
In general, it is theconcept of the invention to esterify this excess ggfatty acid to a substance which has the genegfilformula A -OH in which OH represents a hydfioxyl group and in which A is an organic radi f such nature that the A-OH compound is soluble in mineral oil, relatively nonvolatile\and has a soluble action or 55 tendency in relation to fatty acid soap.
- The A-'OH compound preferably consists of a partial ester of a polyhydric or dihydric alcohol and a fatty acid. Examples of substances which may be used in place of glycerineto produce this compound are ethylene glycol, diethylene glycol, propylene glycol and the like.
Example 3- To prepare a grease basacomiisting of 4 parts of calcium stearate and one part of diethylene glycol monostearate, about- 2'70 parts of stearic acid are melted and heated to approximately 160 C. and about 32 parts of hydrated lime added slowly over a period of about one-half an hour to prevent lumping. When 7 practicaliy all'of the lime has reacted, which may requirefrom to 1 hour depending upon the degree and'type of agitation, about 18' parts of diethylene glycol is added and the temperature raised to 180 0.. The heating is continued until 75 the free fatty acid content has dropped to below reaction proceeds show 30.9%
fifteen minutes. After an ad-' Thus, the salts appropriate to the production of 3 and 4. The final free fatty If the heating is carried out in an open vessel additional diethylene glycol may be required to compensate for loss by evaporation.
Free fatty acid tests on the material as the free'fatty acid after the lime is added, 16.5% after V 14.4% after one hour heating and 13.5% after 1% hours. The addition of 9 parts of diethylene glycol to compensate for evaporation followed by hour heating gives a final free fatty acid of 6% The reaction product is a syrupy mass when hot and upon cooling forms a tan-colored hard waxy mass.
7.5% of this product dissolved in 200 sec. mineral "oil produces a grease. Example 4-To prepare a grease base consisting clear transparent water-free.
hour heating of 4 parts of calcium stearate and one part 0! ethylene glycol stearate, about-'- 276 partsof stearic acid 32 parts of calcium hydroxide, and 121 parts of ethylene glycol are processed as described in Example 3. The reaction progresses about as shown by free fatty acid determinations as follows:
After lime added FFA 29.5 hour heating 14.7 l hour heating; 12.2
6 parts additional glycol 1% hrs. heating 7.6
The product has substantially the same appearance as that described in Example 3. 7.5 parts of this base dissolved in 200 sec. mineral oil gives a clear anhydrous grease considerably are treated in the manner disclosed in Examples about 11.5%.
and has more of the ordinary soap-like feel. It
acid content is is not suitable by itself for preparing a .grease but can be added to oil in small proportions along with the grease bases already described to impart astringy characteristic to the greases.
The grease bases which are made in accordance with the process of the present invention are anhydrous or substantially so. Small quantities of water may be included in them without necessarily destroying their value or their utility. of course, it is recommended that the bases beused in a condition as nearly anhydrous as possible for the reason that the greases which they themselves are adapted tovprovideare in general of improved appearance and superior stability, more uniform in consistency and more easily manufactured to precise specifications. y
In making greases from the grease bases'which I have provided, it'is necessary only to dissolve the base in the requisite quantity-,pf-oil, then cool this mixture either by pouring it into containers or by passing it over a chilling roll- It is recommended that the grease base be dissolved completely in the oilbefore the mixture is chilled, to form the grease. If desired, the oil can be heated to a temperature of around more or less,
to increase'the rate ofdissolution. The greases which are made from the grease bases of the present invention are anhydrous or substantially so. The grease base component, when once dis- 5 solved in the mineral 011, does 'not tend to pre-' cipitate from the grease as in the greases of the moisture variety; and therefore, these greases are particularly well adapted to use for lubricating purposes, under relatively high temperature condltions.
Having. described my invention, I claim:-
1. A method of making a body which is'soluble in mineral oil at room temperature which method comprises, conjointlyfusing fatty acid with calcium oxide lesser in amount than that required r to react with the fatty acid to make a soap; and
esterifylng the balance of the fatty acid with an aliphatic n lyimiric alcohol, to produce a fatty acid at least one free hydroxyl groupf 2. The method of making a grease base which is substantially anhydrous, which method comprhes, reacting a fatty acid with a calcium'salt, reactive with fatty acid to form a soap, but int in amount to react with all of the fatty acid, then reactlng, in situ, the uncornbined fatty acid with a high boiling alcohol, whereby to provide a mas comprised of calcium salt of fatty acid mingled with a fatty acid ester having at :10 least one free hydroxy1 3101111 3, The method which consists in substantially conjointly reacting a fatty acid with lime, insufficient in amount to react with all of the fatty acid, and with a high boiling alcohol adapted to :25 esterify the remainder of the fatty acid, to provide a body consisting of the calcium salt of fatty acid mingled with a fatty acid ester having at least one free hydroxyl group.
4. The method which comprises, reacting lime 49 withaquotaofstearicacidinexcess of thequota required to combine with the lime, then reacting the excess of fatty acid with a high boiling alcohol to pmvide,in the presence of the calcium salt farms;- moms.
from, which method forming a dry soap of a fatty acid in the presence of a quantity. of fatty acid in excess of that required to form the soap and reacting the excess of fatty acid: withan aliphatic alcohol which is reactive. inrespect thereto to form, in situ, a fatty acid ester having at least one free hydroxyl group.
6. A method of making a grease base which comprises, heating a mass of fatty acid partially saponifled with lime with a polyhydric alcohol to esterify the saponiiled component of the fattyacid, to provide in the mass a quota of fatty acid ester having at least one free hydroxyl group, which is soluble in mineral' oil and which possesses the capacity to dissolve the fatty acid component which is saponifled.
- 7. The method ofmaking an anhydrousgrease basewhich comprises, forming a mass containing free fatty acid and fatty acid soap adapted to make a grease with mineral oil, and heating this -mass with a quota of material reactive in respect to the free fatty acid, to provide a reaction ponent in the mass which has at least one free hydroxyl group and which is solublein mineral oil and which is a solvent for thefatty acid soap.
8. A method of making an anhydrous grease base which consists in forming a fatty acid soap adapted to make a grease with mineral oil, and forming a; partial ester of fatty acid which has at least one free hydroxyl group, in situ,durlng at least a portion of the time that thev soap is being formed, the amount of ester formed being sufficient to solubilize the soap in mineral oil suilicient in quantity to make a grease therewith.
9. The method of making an anhydrous body soluble in mineral oil to form a grease therefrom,
which method consists in saponifying a major portion oi. a body of fattyacidito form 'a sub stantially anhydrous fatty acid soap. and in reacting the remaining minor portion of fatty acid with a body adapted. to provide therefrom a reaction component which has at least one freehydroxyl group, which is soluble in mineral oilr which is a .solvent for fatty acid soap and-which is present in suflicient quantity to render all of the said soap soluble in mineral oil.
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