US2411468A - Manufacture of soap - Google Patents

Description

Nov. 19, 1946. L. sENDER MANUFACTURE 0F SOAP Filed Nov. 25, 1943 .Q Q QN mmh@ k UNITED STATES PATENT MANUFACTURE F SOAP Leopold Sender, Baltimore, Md., assignor to The Sharples Corporation, Philadelphia, Pa., a corporation of Delaware Application November 25, 1943, Serial No. 511,705

OFFICE 1 claim. (c1. 25o-4.18,)

The present invention relates to the art of soap making, and was conceived as a method of making soap continuously with the aid of centrifugal separators.

Processes for the manufacture of soap by passing a saponifying reagent continuously into coniiuence with a source of fat, saponifying the fat by passage of the mixture at saponifying temperature continuously through mixing apparatus, and separating spent reagent from soap by centrifugation are described and claimed in the patents of Ashton T. Scott, 2,300,749 and 2,300,750, of November 3, 1942. The present invention is primarily a development and improvement with respect to the procedure of these two patents.

In the processes of the above-mentioned Scott patents, the fat is continuously saponied by treatment with a saponifying reagent such as lye, the saponilication being accomplished by intensely mixing the fat and lye while passing them at a saponifying temperature through mixing apparatus. The resulting soap-containing mass is maintained under intensive agitation until it is passed into a centrifugal separator for removing the spent aqueous reagent from the soap. The soap is grained, and thus conditioned for removal of the spent aqueous reagent, prior to centrifugation, by the addition of a salt solution, or an excess of saponifying reagent which serves as a salting-out agent. In the process of Patent 2,300,750 the salting-out operation is accomplished by addition of the salting-out agent before the start of the saponiication reaction.

The present invention may include any or` all of the features of either of the prior patents to Scott discussed above. It includes steps of effecting continuous saponication by passage of the fat and saponifying reagent together through a saponifying mixer, graining the mixture by addition of a salting-out agent either simultaneously with the saponifying reagent or subsequently to addition thereof, and centrifugation of the mixture of spent saponifying reagent and grained soap resulting from the saponication while the grained soap is in a condition of substantially uniform dispersion in the spent saponifying reagent.

'Ihe novel feature of the present invention consists in the fact that the mixing step by which intimate contact of the saponifying reagent with the fat is attained to cause the saponification and to bring the soap formed by the saponifying reaction into a state of uniform dispersion is divided into two steps, and a step of aging is interposed between these two mixing steps. In the practice of the present invention, the fat and reagent are rst mixed during maintenance of a saponifying temperature to cause saponilcation, and the soap formed as a result of the reaction is grained. The resulting mixture is then subjected to aging by maintenance of a period of relative quiescence or lesser degree of agitation, and the mixture of grained soap and spent saponifying reagent is then subjected to a further period of agitation in order to provide sufficient dispersion of the soap in the aqueous phase to afford substantially uniform distribution of the Soap in that phase as the mixture is passed to the centrifugal separator for separation of the spent reagent from the grained soap.

The succession of steps of the invention as described above, may be performed both in the rst stage of soap making as described in connection with the rst stages of the respective prior patents to Scott discussed above, and in any or all of the series of subsequent saponifying stages of which each involves addition of saponifying reagent, graining and separation as described in the prior Scott patents. Each' stage in which a saponifying reagent is added is thus referred to as a saponifying stage herein, eventhough the addition of saponifying reagent in the last such stage may be wholly or partly for the purposes of recovering glycerine and preparation for finish-J ing, and `no actual saponication occurs in such stage.

By the practice of the invention as discussed above, the following advantages are attained. The quiescent treatment or churning obtained in the aging step causes a change in the mixture which facilitates subsequent centrifugation.Y It has been found that, in cases in which saponied and grained mixtures presenting substantial difculty of separation are obtained in the practice of the Scott patents, the practice of the intervening aging step in accordance with the present invention assists in avoidance of these difficulties.

'Ihe aging treatment also provides a longer time of contact between the fat and lye, or the formed soap and lye, and this longer period of contact with the saponifying reagent tends to destroy constituents of the mixture which would otherwise cause rancidity of the soap after the soap-making operation has been completed.

In addition to the above advantages, the aging treatment, by giving a longer time of contact of the unsaponified fat with the lye, assists in depletion of the lye and attainment of a higher degree of saponication.

The detailed nature of the invention and its attendant advantages will be better understood by consideration of the following detailed description in the light of the attached flow sheet, in which the single figure illustrates a preferred embodiment of the invention.

Referring to the flow sheet by reference characters, fat from container lil is passed into conluence with saponifying reagent from container I I. This saponifying reagent may be an aqueous solution of lye and salt, designed to effect saponication of the fat and graining of the soap formed by the saponifying reaction, as described in Scott Patent 2,300,750. As illustrated in the flow sheet, the solution of lye and brine employed in the rst stage of saponification may be a solution derived in whole or in part from the step of separation of a subsequent stage; i. e., the process may involve counter-,current operation as described in the prior Scott patents. The fat from container Il] and saponifying reagent from container il may be pumped into confluence with eachother' by'` pumps I2 and i3, which pump these' material-s to' and .through the mixer' Ill in' the desired ratio. The reaction mixture, or its constituents, isv (are) heated to a temperature (e. gv., 200 F.) sufficiently high to effect saponiication of most of the fat during passage through the mixer iii. The mixture is maintained in a state of intensive agitation during passage through'l the mixer' iii in order to insure rapid saponiiication of the fat.V When a graini-ng' agent suoliY as salt 'isi included with the saponifying reagent-y the' soap i's lgrained promptly upon formation thereof. It is possibile, however, to introduce the saponifying reagent and graining agent separately, as described in Scott Patent- 2,00,749, and when operation of this type is accomplished, the grain'ing agent is preferably added before the' reaction mixture leaves the mixer it, orat least before it enters the ager I5.

'The reaction mixture is passed continuously from mixer id through an aging tank i5. The mixer it is' preferably provided with agitating blades to' insure violent agitation, but the ager I need not be' provided with such elements. It isi desire-bie' that the mixture be gently agitated during 'passage through the' ager i5,` but this result can be accomplished. either by the" natural movement of the' mixture through th'a't tank, or by provision of agitating blades which provide much: less violence: than that maintained in' the mixerV I4.

As the? result of the' aging step performed dur'- in'g' passage of the mixture through the ager f the material flowing from that mixer will ordinarily be le'ss' nearly uniform in composition than that flowing into container i5 fron'i mixer M; In order' to insure eii'cient centrifugation of this material, it isdesirable to a higher degree of agitation that maintained in container le, atleast for a brie'ff period before centri-fugationi.4 This iis accomplished: by passingl the 'material through a'. mixer I6 which provides the desired degree' of agitation and' ef'- fects uniform`-l dispersion of the soapin th'e' aqueousl phase before the` materiali enter-si the'.` centrifugal'. f

From mixer'Y I6, the' mixture of spent' reagent and graine'dl soap'li's passed tocentrifugal. l'! for separation of the spent reagent fromI the soapas in the YtwoSco'tt pa'terlits referred toi above'.

After discharge from centrifugal I'l th'e largely saponiied mass containing the soap formed in the first stage is subjected to a second stage of saponication in order to complete conversion -of the source of fat into soap. As in the prior Scott patents, this may be accomplished by introduction of the saponifying reagent into the cover of centrifugal Ii. Thus, a solution of lye and brine, which may either be a fresh solution or a solution derived from' a subsequent stage of treatment, is introduced into the cover of centrifugal H by pump IB, and the resulting mixture is passed thence by pump 2e to mixer ZI, through this mixer 2l to ager 22, and from ager 22` through mixer' 23 to centrifugal 24, these elements of the iiow sheet accomplishing the same functions as are performed by the pumps and elements I4, I5, I6 and I'l of the rst stage of the process, as described'above. y

The soap discharged from the second stage centrifugal 24 may be subjected to further treatment, as described in the' two Scott patents referred to above, andif such further treatment includes further steps of saponification, they will preferably include an aging step, as described above with respect to the first two stages of treatment. The performance of the step o'f aging has a particular advantage in the' last stage of soap making, since the maintenance of` the fully saponiiiedl soap-containing mixture in contact with an excess of the free alkali for' al substantialpe'riodl of time? assists in avoiding rancidity, as discussed. above, and it is therefore desirable to provide an aging period after the fat has been fully saponi'fied.

The partly' spent aqueous solution discharged from the centrifugal 24 may be passed by pump 25A to' container' ifi for re-use in the first stage of the' process, in order to make the' process truly counter-current, as' described in the Scott patents referredv to above.

Various modifications" in the' above-described procedure are available to the person skilled in the art', and are' hence within the scope of the invention. For' example, instead of including the graining reagent' as a part Yof the saponifying solution, this grain'ing" reagent may he'V added subsequently to' the saporliifying reagent, as described iii Scott Patent 2,300,749.- pos'sib'ilities for'modic'atiorl falll within the scope of tine invention,- and' Ido not therefore, wish' to be' limite'dl excep-tibythe scope olf the following claim.

In the manufacture of soap, the' process comprising continuously converting fat into soap by mixing'said fat vigorously with ai sa'ponifyin'greagent' at a' saponifyin'g temperature during passage' through a mixing Zone,graining. the soap resulting from .said mixing' step', thereafter passing.' the resulting mixture of grainedvsoap and aqueous phase' through an aging zone in: which th'e mixture is' churne'd by agitation 'of a' degrl'ee less than. that maintained in the' preceding mix'.

ing zone', passingv a'q'e'ous phase andv grained soap v from said'. aging zone into a secondi n'rrixingiv aon'e in which they are agitatedV more vigorfousl'y than in the aging Zone until substantially uniform dispersion of. the soapri's obtained, and' fina'ily passing the mixture resulting from agitation in saidi last-mentionedY mixing ZoneA to a centrifugal separator and thereby separating th'e grained soapfrom aqueous phase.

VLit'oroLD- senese'.

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