Patented May 12, 1936 UNITED STATES PATENT OFFlCE PREPARATION OF EMULSIFYING SOAI'S Jack Robinson, Wood River, 111., assignor to I Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application January 25, 193

Serial No. 653,477

6 Claims. (01. 875)' This invention relates to the purification of I I may repeatedly treat a. Mid-Continent lubricatsulfonic soaps and it pertains more particularly ing oil stock with concentrated or fuming sulfuric to the removal of salts from preferentially oilacid, separating and withdrawing the sludge from soluble petroleum sulfonic soaps of the type emthe treated oil. I may then'neutralize-the sour ployed in the preparation of soluble oils, deteroil with caustic, thereby forming mahogany soap gents, wetting agents, etc. and large quantities of sodium sulfate. If I en- The sulfonic soaps which are hereinafter called deavor to wash out the sodium sulfate with water mahogany soaps may be prepared in the I immediately run into emulsion difficulties and manner described by U. S. Patents 1,196,274 and I find that such separation is impossible. Alcohol 10 1,286,17 9, or they may be prepared by neutralizwill remove the mahogany soaps from the oil but 10 ing the sulfonic acids prepared by the method of it removes the sodium sulfate therewith. U. S. Patent 1,087,888. These mahogany soaps' In accordance with my invention I wash the may be used as emulsifiers as described in U. S. neutralized oil with a, 3-10% solution of sodium Patent 1,230,599. I have found that the mahydroxide, preferably using a number of dumps l5 hogany soaps as heretofore produced contain or using acountercurrent washing system. With large amounts of sodium sulfate and other salts, this percentage of sodium hydroxide I prevent and that these salts and impurities are extremely emulsification and I also efiect the separation of detrimental, particularly'when the soaps are to the sodium sulfate from the mahogany soap. be used as wetting agents, detergents, emulsifying After counter-current treatment with from one- 29 agents and the like. The object of my invention half to four volumes of the caustic solution, or is to provide a mahogany soap which is substanafter one or more dumps with about one-half totially free of salts and therim rities, two volumes of the caustic solution I may extract A further object of the invention is to avoid the mahogany soap from the oil with alcohol in the expense and trouble of using high proof accordance with well known refinery practice.

(70%) alcohol for the extraction of mahogany The extracted mahogany soap, however, will be 25 'soaps from impurities. A further object is to substantially different from mahogany soap hereavoid emulsion difliculties in the purification of tofore extracted because it will not contain apmahogany soap and to recover the purified soap preciable amounts of sodium sulfate. The slight in a form which is particularly desirable for the alkalinity of the finished product may be neupreparation of emulsifying agents, wetting agents tralized with rosin acid or a fatty acid to prepare 30 and the like. the finished emulsifying compound, wetting agent Prior attempts to remove sodium sulfate from or detergent. -mahoganysoap have indicated that there is a dis- Instead of washing a neutralized oil prior to persion of the sodium sulfate in the oil phase the extraction of themahogany soap, I may wash from which mahogany soap is extracted, and the extract per so with caustic. In fact, this 35 there is some indication that the sodium sulfate procedure is highly desirable because it requires forms a salt with the mahogany soap which furmuch smaller equipment and a smaller amount ther interferes with the separation. The sodium of caustic wash liquor. I prefer to use about a sulfate cannot be washed from the mahogany 5% solution of sodium hydroxide'but the concen- 40 soap solution with water chiefly because of the tration of said solution may vary from about 40 emulsion difliculties. I have discovered that by 3% to 10% or more. Here again I may use a maintaining the concentration of electrolyte continuous countercurrent washing system, or I above a certain-minimum value, I-mayeffectively may employ a plurality of separate dumps;in prevent emulsification, and furthermore, I have which ease I may use t caustic which has been fmmd sodmmsmfateandmahoganyoapmay used for removing the final traces of salt'from be read Separated by means of an alkalme one body of mahogany to extract further amounts tion More speclficaliy I found that W of salt from a less pure'mahogany soap. The the impure.mahga'n.y Soap 15 Washed i mechanicalv features and details of my opera- 3-10% solution of sodium hydroxide, there is no ti f t f the resent inventi n and 50 emulsification difficulty and the sodium sulfate is on no par 0 p 0 50 they will not therefore be described in detail. readily removed. Iprefer to carry out the washing step in a 10-20% solution of soap in naphtha. I f also efiect the wasmng p caustlc The process is applicable to the mahogany soap tion in the presence of a light hydrocarbon dilelther before or after the soap is extracted from 1161113, Such as naphtha, and the amount of thls the oil in which it is first formed. For example, diluent may be varied Within Wide limits I prefer 55 to use about -90 of naphtha in washing. soap from a lubricating oil of intermediate viscosity.

When removing impurities from extracted mahogany soap I prefer to avoid the use of naphtha diluent and to eifect the removal of sodium sulfate in a hot aqueous solution. The impure soap may be dissolved in hot waterto form a 20-30% solution. I add to this solution, with stirring, sufilcient strong sodium hydroxide to bring the concentration of the aqueous phase to.3-10%. The mixture is allowed to settle while it is hot. I have found that the use of hot water in combination with the regulation of the alkalinity of pH value makes it possible to obtain a better separation of impurities, freedom from emulsion difliculties and an improved product.

An important use of my purified mahogany soap is in the preparation of oil emulsions; An oil emulsion or a soluble oil which enjoys wide commercial use has about the following composition: about 3% soda rosin soap, about 10% mahogany soap, 1.5% water, 1.5% alcohol, and 84% light mineral oil (viscosity about 50-80 seconds at F.) interfereswith the emulsification of. the oil, and it impairs the stability of the finished emulsion. By eliminating this impurity I overcome these difficulties, and I have evendiscovered that the alcohol contentmay be reduced or even eliminated without impairing the quality or stability of the emulsion. It will be seen from the above formula that a small amount of water and of soda rosin soap is necessary. I find that this amount of water and the amount of soda for making the soap may be left in the mahogany soap when the sodium sulfate is being removed therefrom, and thus I merely have toadd a little rosin'acid and light mineral oil with perhaps a small amount of alcohol to prepare the finished soluble oil composition. Another method of making soluble oils takes advantage of the diluent efiect of the oil which is to be emulsified. I combine the impure mahogany soap and the mineral oil in the proportions specified in the formula. I then wash this mixture with 13-10% sodium hydroxide solution, neutralize the excess alkalinity with rosin acids, etc. and add other necessary ingredients.

The alkalinity of the washed mahogany soap may also be utilized in the preparation of detergents and wetting agents. However, if it is desired to obtain pure mahogany soap, this final The presence of sodium sulfate oils, such as sulfonated oastor oil,-also that other alkalies such as potassium or ammonium hydroxide may be used. Other expedients will be apparent to those skilled in the art.

I claim:

1. The method of making a soluble oil from mahogany soap, which comprises washing impure mahogany soap with a 3% to 10% aqueous solution of sodium hydroxide, removing the aqueous washing solution and impurities from the slightly alkaline mahogany soap, neutralizing the alkalinity of the washed mahogany soap with a soapforming acid, and admixing said neutral soap with a light mineral oil.

2. The method of preparing an emulsifying composition from oil soluble mineral oil sulphonic soaps which comprises washing said soaps containing sodium sulfate and other impurities with a 3%; to 10% aqueous solution of alkali metal hydroxide whereby the formation of serious emulsions is avoided, separating the sulphonic soap from the aqueous layericontaining sulfates and impurities, and neutralizing the alkalinity of the soap by adding a soap-forming acid thereto.

3. The method of claim 2 wherein the ma- 5.

hogany soap is diluted with a large amount of light mineral oil.

4. The method of claim 2 wherein the soapforming acid is a fatty acid.

5. The method of claim 2 wherein the soapforming acid is a rosin acid.

6. The method of making a soluble oil from impure mahogany soap which comprises adding to said soap the light mineral oil to be used in the soluble oil, washing the mixture of mineral oil and impure mahogany soap with a 3% to 10% aqueous alkali metal hydroxide solution, separating the aqueous phase and impurities from the oil phase, and neutralizing excess alkalinity in the oil phase with a soap-forming acid to form an emulsifying soap which will supplement the mahogany soap in the soluble oil.

JACK ROBINSON.