US2235628A - Process of making soap - Google Patents

Description

PROCESS OF MAKING SOAP Filed Aug. 1, 1959 Japan/rum: JAPO/WFYl/VG Patented Mar. 18, 1941 UNITED STATES 2,235,628 I raooass or MAKING SOAP Benjamin Clayton, Houston, Tex., assignor to Refining, Inc., Reno, Nev., a corporation of Nevada Application August 1,

14 Claims.

This invention relates to a process of making soap and more particularly to a rapid process in which the saponification reaction is carried on at a relatively high temperature.

The step of reacting a saponifying'reagent such as, for example, a caustic soda solution, with saponifiable materials such as glycerides of fatty acids, other esters of fatty acids, fatty acids, or other saponifiable acids, is a slow and time consuming operation in conventional kettle processes. small amounts of the saponifying reagent and saponifia-ble material are brought into thorough contact, the saponification of glycerides or other esters goes forward at a relatively low rate at temperatures ordinarily employed in. making soap. Since a high quality soap must be substantially neutral, no appreciable excess of saponifying reagent canbe employed and it is difficult to carry the reaction to substantial completion. When saponifying fatty acids, although the reaction is ordinarily quite rapid, a thick viscous reaction product which is difllcult to handle is usually obtained and unsaponifled acids are occluded in the soap massesformed so as to render complete saponification extremely difficult.

i The process of the present invention contemplates separating the glycerine or other volatiles, resulting from the sapon'ification of glycerides or other esters, from the soap byvaporization. The temperaturesnecessary for such vaporization, even if carried on under vacuum conditions, are usually sufficient to damage esters or acids remaining in the saponified mixture. The resulting degraded products contaminate the soap and volatile materials and it is therefore important to produce substantially complete saponificationi prior to raising the temperature of the mixture to vaporizing temperatures for the unsaponifiable materials such as glycerine or higher fatty alcohols. Even in the saponificae tion-of fatty acids, it is many times desirable to increase the temperatures of thesaponified mixture above'the decomposition point of the fatty acids particularly with lower grade fatty acids materials frequently contain sterols and other ization at high, temperatures.

higher alcohols which can be removed by vapor- Also, the high I temperatures in the vaporizing'step bleach and de-odorizethe soap. By employing rapid heating steps ,such as stream heating steps, high temperatures which would cause degrading of Even in continuous processes where 1 1939, Serial No.287,857

the saponifiable materials in batch heating steps can be employed.

By preheating the materials-employed in the soap making process to a relatively high temperature prior to contacting the same, it has been found that the reaction is rapidly carried to completion-both with the esters and acids or mixtures thereof since the high temperaturereduces the viscosity of both the reacting materials and the reaction products' The reaction temperatures contemplated are considerably higher than those ordinarily employed in conventional soap making steps and are preferably just below the temperatures which would cause degrading 0f the saponifiable materials. A high quality soap, substantially free of uncombined saponifiable materials and alkali, can be rapidly produced. Also the resulting saponified mixture can be heated to temperatures higher than those which will damage the esters or acids employed, in order to remove vaporizable impurities such as glycerine and sterols therefrom and also to bleach and de-odorize the soap. No degrading of the saponifiable materials results and the resultant soap and other products are not contaminated with degraded materials. Also materials whichreact very slowly, if, at all, with s'aponifying reagents under ordinary low temperature conditions are rapidly saponified by preheating the reacting materials to the relatively high temperatures contemplated 'by the I present invention. 7

It is therefore an object of the present invention. to provide a process in which extremely rapid substantially, complete saponification is effected. I

Anotherobject of the invention is to provide a process, of making soap in which vaporizable impurities are removed from the soap by evaporation at high temperatures and substantially complete saponification is effected before reach- -ing these high temperatures so that damage to .saponifiable materials is prevented. I Another-object of v the invention is to provide a process of making soap in which at least the saponlfiable material is heated to a relatively high temperature below that, at which the saponifia-ble-material is damaged prior to contacting the same with the saponifying reagent.

Another object of the invention is to provide a process by which difilcultly saponifiable materials are rapidly and substantially completely converted into soap.

A further object. of the invention is to provide a.process ofmaking soap in which saponifiable materials and a saponifying reagent are contacted at a relatively high temperature below that at which damage to the saponifiable material occurs to produce substantially complete saponification in a brief period of time.

A still further object of the invention is to provide a process of making soap in which the soap making materials are heated to a relatively high temperature approaching temperatures at which the saponifiable material is damaged prior to contacting the materials in order to reduce the viscosity of the reacting materials and reaction products so that substantially complete saponification can be efiected.

Other objects and advantages of the invention will appear in the following description of the preferred embodiments of the invention described in connection with the attached drawin which is a diagram of an apparatus suitable for carrying out the present invention.

Referring to the drawing, a saponifiable material may be withdrawn from a source of supply shown as a tank ill by a proportioning pump II and delivered by a pipe i2 to a heating device indicated as a heating coil iii. The saponifiable material is forced by the pump ll through the heating coil l3 to a mixer I4 where it is thoroughly mixed in flow with the saponifying reagent. The saponifying reagent may be withdrawn from the tank l5 by a proportioning pump l6 and delivered by a pipe H to a heating coil [8 through which it is forced and delivered by a pipe I! to the mixer l4. The proportioning pumps H and I6 may be driven by any suitable means, for example, a variable speed motor 2! with a variable speed device indicated at 22 positioned between the pumps so that the speed of both pumps as well as the relative speed of the pumps may be varied. Any other type of proportioning device which will deliver accurately proportioned amounts to the mixing device [4 can, of course, be employed.

The mixture from the mixer I4 is forced by the pumps 2! and I6 through one or more heating coils indicated at 23 and delivered by a pipe 24 containing a valve 25 into the interior of an evaporating chamber 26. Heat may be supplied to the heating coils l3, l8 and 23 by any suitable means such as burners 21 for gaseous or liquid fuel or by immersing the heating coils in a heated liquid such as mineral oil or low melting point alloys. Saponifiable material and saponifying reagent are thus heated in the coils i3 and It to a relatively high temperature, and are thoroughly admixed in flow in the mixer l4. The saponification reaction begins in the mixer l4 and is substantially completed in the mixer, or at least before the temperature is substantially increased in a heating coil 23. The substantially completely reacted mixture is heated in one or more coils 23 to a temperature suflicient to cause separation of vaporizable material as vapors in the evaporating chamber 26. The coil 23 should be sufficiently long to provide enough time so that enough heat can be imparted to the mixture to cause substantially complete separation of vapors in the vapor separating zone and if necessary two or more coils in series, heated to progressively higher temperatures, may be employed in lieu of the single coil 23 depending upon the time necessary to increase the temperature of the material being treated. The pressure in the final heating coil is preferably sufficiently low that substantial vapor formation takes place therein. This enables a greater amount of heat to be imparted to the mixture at a given temperature so that separation of vaporizable materials in vapor form can be rapidly accomplished in the vapor separating zone.

The evaporating chamber 26 is preferably surrounded by a heating jacket 28 through which any desired heated medium such as steam or heated mineral oil may be circulated by the pipes 29 and 30 and the heated materials entering the evaporating chambers are preferably discharged against the heated walls thereof by the nozzles 3|. These heated materials flow down the heated walls of the evaporating chamber 26, vapors are liberated therefrom and pass upwardly through the central portion of the evaporating chamber through a substantially unimpeded path to the vapor pipe 32 by which it is delivered to the condenser 33. A portion of the vaporizable material is condensed in the condenser 33 and delivered to the receiver 34 while vaporizable materials having lower boiling points are withdrawn from receiver 34, condensed in the condenser 35 and delivered to the receiver 36. The vacuum is maintained in the evaporating chamber by the vacuum pump 31 withdrawing uncondensed vapors from the receiver 36. The condensed materials are withdrawn from the receivers 34 and 36 through pipes 36 and 33 by any suitable means such as pumps (not shown).

The soap is delivered into the housing 40 of a screw conveyor 4| by which it is pushed from the evaporating chamber and discharged to the atmosphere at 42. The soap is cooled during its passage through the conveyor housing 40, for example, by the cooling jacket 43 so as to form a vacuum seal in the conveyor housing and also lower the temperature of the soap below that at which it will be damaged by contact with the atmosphere. A valve 44 adjacent the discharge end of the conveyor is provided so that the vacuum can be maintained under starting conditions before a vacuum seal is formed by the soap in the conveyor.

If the saponifiable material is solid at ordinary temperatures, it may be maintained at a temperature sufficiently high in the tank [0 to render it fluid. This is unnecessary for saponifiable materials liquid at ordinary temperatures but solid fats or other solid saponifiable materials can be heated to temperatures of to 212 F. and with some materials somewhat higher without damage due to contact with the atmosphere. The saponifiable material is, however, heated in the coil l3 to temperatures higher than those permissible when the saponifiable material is in contact with the atmosphere. For example. temperatures of 250 to 420 F. have been successfully employed. The saponifiable material is maintained under super-atmospheric pressure in the coil l3, out of contact with the air and sufficient velocity is maintained therein to prevent local overheating. The highest temperature which can be employed without degrading the glyc'erides of fatty acids and fatty or other soap making acids is in the neighborhood of 480 F. although the temperature will vary somewhat with different materials and the degrading temperature of the material being saponiiied determines the upper limit to which the material may be heated in the coil [3. It is also desirable to preheat the saponifying reagent, in order to maintain the temperature of the resultant mixture as high as possible after the saponifiable material and reagent have been contacted. The

' saponifying reagent is preferably heated in coil l8 to approximately the same temperature as the saponifiable material discharged from coil l3, but because of the corrosive nature of the saponifying reagent, particularly if aqueous solutions of caustic alkalies are employed, a lower temperature may have to be employed unless the heating coil 21 is corrosion resistant. Thus, with certain apparatus it may be found impractical to go above 220 F.

When glycerides of fatty acids are being saponified, the preheating of the glyceride with or without preheating the saponifying reagent, such as caustic soda, decreases the viscosity of the glyceride, promotes better mixing of the materials and speeds up the reaction. For example, it has been found by actual test that the extent of saponification is approximately twice as great at 370 F. as it is at 270 F. Thus, the higher temperatures insure substantially complete saponification whereas such substantially complete saponification is very difficult to obtain at lower temperatures. Thus with the higher temperatures substantially complete saponification can readily be obtained prior to heating the reacted mixture to glycerine vaporizing temperatures. .Also the higher temperatures reduce the pressure necessary to force the initial materials and the soap mixture through the process. This enables more accurate proportioning of the materials to be effected as it is difficult to accurately proportion when working against very high pressures. It is important that the proportions be such that a substantially neutral soap is produced as excess alkali tends to decompose glycerine and other alcohols while excess fatty materials tend to be degraded to produce an inferior soap.

- In order to insure that substantially all of the glycerine and other vaporizable materials are removed from the soap, it is, in general, necessary to raise the temperature of' the mixture in the discharge portion of the coil 23 above the melting point of the soap produced when the soap is in anhydrous form. Such temperatures range between approximately 480 F. to 620 F. depending upon the soap and volatiles being produced. These temperatures must usually be also maintained in the evaporating chamber 26 so that the soap is deposited in the bottom of the chamber in molten form after glycerine, water, and other vaporizable materials have been removed therefrom. Such temperatures are usually above th degrading temperatures of the glycerides or acids. When fatty acids are being saponified, the reaction with a saponifying reagent such as caustic soda is extremely rapid, but, unless the fatty acids and preferably the saponifying reagent, are preheated, solid or viscous soap is formed in large masses as soon as the materials are contacted and uniform saponification is diffi. cult as unsaponifiable fatty acids are occluded within the masses of soap formed. Preheating of at least the fatty acids so as to maintain a relatively high temperature reduces the viscosity of the soap formed until thorough admixture can be effected and substantially complete saponification rapidly produced. This temperature need not be above the melting point of anhydrous soap, since considerable water is always present during the saponiflcation step such that the soap is in fluid form below the melting point of anhydrous soap, and should be below the decomposition temperature of the fatty acids.

High quality soaps from fatty acids can, therefore, be rapidly made and if no appreciable vaporizable impurities are contained in the fatty acids, the resultant heated soap can be discharged directly into a cooling device, for example, the conveyor housing 40 and thereby cooled and extruded to the atmosphere as a hydrated soap. Ifit is desired to remove at least a portion of the moisture from said soap, it may be discharged at the temperature of reaction into an evaporat ing zone such as the evaporating chamber 26. No vacuum is necessary although preferably the soap must be maintained out of contact with the atmosphere until it is cooled to a lower temperature, for example 120 F. as soap is readily damaged by contact with the atmosphere at substantially higher temperatures. As hereinbefore indicated, the color and odor of the soap can be markedly improved, particularly Where impure fatty acids are being saponified, by raising the temperature in the discharge portion of the coil 23 to temperatures between, for example, 450 to 620 F. and then discharging the same into the vacuum chamber 26. Certain colored and odorous compounds are apparently destroyed by such higher temperature and constituents such 'as sterols and other higher alcohols are evaporated from the soap and condensed in the condenser- s 33 and 35.

When saponifying materials containing substantial quantities of other esters of fatty acids for example, a wax such as sperm oil, which contains primarily cetyl palmitate, saponification is rapid and substantially complete and cetyl alcohol is separated in vapor form from the soap. Preheating temperatures of approximately 300 F. and vaporization temperatures of approximately 575 F. have been successfully employed without substantial degrading of the saponifiable material.

Thus, by the present process, rapid and substantially complete saponification of glycerides or other alcoholicesters of fatty acids or fatty or other saponifiable acids can be effected in an extremely brief period of time. The saponifiable material is heated out of contact with the atmosphere in the coil l3 to temperatures which would damage the saponifiable material if in contact with the atmosphere. The heating is carried out with sufficient rapidity and the saponifiable material is subjected to the high temperatures for such a brief period that no damage thereto is caused. The saponification step is carried out at high temperatures, and out of contact with the atmosphere such that a high quality of soa is a rapidly produced. Also, if glycerine or other vaporizable materials are to be removed from the soap, the saponified mixture can be heated to temperatures above the degrading point of the esters or acids without danger of contaminating the soap or vaporizable materials with degraded products of the saponifiable materials, since substantially complete saponification is effected before the higher temperatures are reached. Heating in the coil 23 is also under pressure and out of contact with the atmosphere and suflicient velocity is maintained in the coil to prevent local overheating. The materials in the process are subjected to the high temperatures employed for brief periods of time only. Thus, the entire system is closed from the atmosphere from the entrance of the saponifiable and saponifying materials to the points of discharge of the cooled soap .and condensed vaporizable materials and high quality substantially neutral soap free of volatile materials 'is produced in a few minutes. As before indicated other saponiflable acids or esters of such acids, for example, other vegetable or animal waxes such as wool fat or acids such as abietic acids can be treated to produce soap and, if desired, remove volatile materials from the resultant soap by the process of the present invention.

The saponification reagent will vary with the type of soap desired. Thu aqueous solutions of alkali metal compounds such as hydroxides or carbonates can be employed to produce soluble soaps while solutions or slurries of alkaline earth metal compounds, such as calcium hydroxide, can be employed to produce insoluble soaps. Other solvents or suspending liquids such as alcohol can, of course, be employed instead of water with the saponiflcation reagent. The temperatures of preheat and the vaporizing temperatures will, of course, vary with the materials being treated and may in some instances exceed the temperatures hereinbefore given.

The vaporizable materials removed from the soap can usually be recovered in substantially pure form and substantially free from water by fractional condensation of the vapors from the evaporating chamber. Thus, if relatively pure glycerides are being saponifled, highly concentrated substantially pure glycerine can be produced or all or a part of the water can be condensed with the glycerine and later removed, if desired, by fractional distillation. The higher alcohols which occur either free or combined in other saponifiable materials such as animal or vegetable waxes are usually insoluble in water and can be separated by gravity or salting out even if condensed with the water. Centrifugal separation of such condensed mixtures is particularly effective either with or without a salting out agent such as sodium chloride or sulfate. Mixtures of glycerides, fatty acids, abietic acids, waxes, etc., may, of course, be saponified by the present process and the condensed volatile materials separated by fractional condensation or distillation, gravity or centrifugal separation with or without salting out agents or various combinations of these steps.

rom the foregoing it will be apparent that an important feature of the invention resides in preheating the fats or fatty acids or other saponifiable material to a temperature greatly in excess of that required to render it flowable, for the purpose thereby of securing instant and complete saponification when admixed with the saponifying reagent. The saponified mixture therefore, when later subjected to the drastic distillation or vaporization temperature in the coil 23, being free of unsaponified material, is not discolored or injured by such drastic second stage treatment. Thus, the invention contemplates a twostage process in which saponificaticn takes place prior to the drastic temperature imparted by heat treatment in the coil 23.

By preheating th oils or fatty acids or other saponifiable materials, saponification occurs with rapidity and the viscosity of both the reacting materials and the soap is decreased such that occlusion of unreacted materials in masses of the soap is prevented. A lower pump pressure is therefore eniployable. Proportioning of thesaponifiable and saponifying materials is likewise facilitated. This enables a substantially neutral mixture to be produced such that excesses of either alkali or saponifiable materials are not present. An excess of saponifiable material fying reagent.

would be degraded by the drastic temperatures and also an excess of alkali tends to attack and degrade the glycerine or other alcohols present. By rapidly preheating to temperatures just short of the degrading temperature for the saponifiable material, the saponiflcation reaction takes place so quickly that the drastic temperatures may be applied substantially immediately after mixing and the time at which high temperatures are applied to the materials in the process is drastically reduced.

The preheating temperature is applied in stream flow whereby to prevent injury to the fats. This temperature must be considerably higher than that required to make the fats flowable in order that the fats or fatty acids are instantly saponifled when admixed with the sapcni- Although the preheating necessarily varies in accordance with the saponifiable materials employed, it isnevertheless critical for any given oil. Thus, for the usual saponifiable fats, the preheating temperature should be not less than 250 F. Nevertheless this preheating temperature should be less than the temperature which is imparted to the mixture following saponiflcation in order to render the soap molten when anhydrous.

As hereinbefore recited, the process is operable when fatty acids are employed as a saponiflable material without imparting additional heat after the saponification step. This is for the reason of glycerine or similar vaporizable materials and therefore it is unnecessary, in all instances, when employing the process with fatty acids, to impart the drastic distillation temperature in the second stage coil treatment, represented by numeral 23. The preheating temperature must nevertheless be of high order when employing fatty acids and desirably not less than 250 F. to overcome the tendency of viscous masses of soap being formed which would occur at .the lower conventional temperatures.

When employing fatty acids as a saponifiable material and when omitting the second stage distillation step, the saponified material may be spray dried into the chamber 26 and may be continuously removed therefrom without breaking the vacuum because it is not necessary to remove all of the moisture. The means for removing the spray dried particles without breaking the vacuum may be similar to that disclosed in Thurman Serial No. 42,348, filed September 26, 1935. Thus, soap of any desired moisture content may be directly produced.

By the employment of the term saponifiable as used in the claims, we intend to embrace and include either saponiflable fats or saponifiable fatty acids or mixtures containing either or both. The term is thus used in the commercially accepted sense to embrace divers materials reactive with alkali to produce soap.

This application is a continuation in part of my application Serial No. 166,161, field Septem-.

ber 28, 1937.

It is understood that the invention is not to be limited to the details disclosed but may be varied within the scope of the following claims:

I claim:

1. A continuous process for making soap which comprises the steps of: preheating a saponifiable material to a temperature not substantially below 250 F., and sufficiently high to cause rapid and substantially complete saponification thereof when admixed with a saponifying reagent, mixthat fatty acids contain no substantial amounts mg a saponifying reagent with said preheated saponifiable material in stream fiow and in a zone substantially closed from the atmosphere whereby the saponification of said material is rapidly carried to substantial completion to form soap, thereafter advancing said mixture to a heating zone to rapidly heat the same to a temperature sufficiently high to cause the impurities to be separated in vapor form when said mixture is introduced into a vapor separating zone and above the melting point of soap when said impurities have been separated, introducing. the mixture into a separating zone, continuously withdrawing vapors of said impurities and promptly removing the purifiedsoap from said chamber before the same is damaged by high temperatures.

2. A continuous process of making soap which comprises the steps of preheating a saponifiable material under super-atmospheric pressure and out of contact with-the atmosphere to a temperature substantially above that at which said material is damaged in contact with air and sufficient to cause rapid and substantially complete saponification thereof when mixed with a saponifying reagent but insuflicient to render the soap moltenwhen anhydrous, admixing the saponifying material with a saponifying reagent, advancing a stream of the heated and substantially completely saponified mixture through a separate heating zone and there heating the mixture during its advancement therethrough to a temperature in excess of that maintained in the saponification step and sufficient to render the soap molten when anhydrous, discharging the mixture into a vapor separating zone, withdrawing the vapors. therefrom and removing the anhydrous molten soap before injury thereto.

3. A quick and continuous process for makingsoap comprising the steps of: pumping saponifiable material in a heated condition of notless than 250 F. into contact with a stream of saponifying reagent and there effecting substantially immediate and complete saponification in a zone substantially closed from the atmosphere of the saponifiable material whereby to avoid the formation of viscous masses of soap and the presence of unreacted materials, introducing the thus saponified mixture, by superatmospheric pressure, to a vapor separating chamber while at a temperature suiiicient to remove, as vapors, the vaporizable material from the mixture, withdrawing vapors from said chamber and withdrawing the thus purified soap therefrom before injury thereto.

4. The process of making soap which comprises: preheating a saponifiable material to a temperature between approximately 250 F. to 480 F., continuously mixing a saponifying reagent with said preheated material, while excluding air, whereby to eifect rapid and substantiallycomplete saponification thereof free from substantial quantities of unsaponified saponifiable materials, thereafter heating said soap to a temperature between approximately 480 F. and 620 F., introducing the mixture to a vapor separating chamber and removing the vaporizable material in vapor form from said soap.

5. The process as defined in claim 4 in which the purified soap is continuously cooled to a temperature below approximately 120 F; before contacting the same with the atmosphere.

6. A continuous process for making soap and pressure on said stream of recovering glycerine comprising the steps of: pumping streams of saponifiable and saponifying materials to a mixing zone, preheating at least the saponifiable material in its stream fiow'advancement to said mixing zone to a temperature substantially above the fiow point of said material and not substantially less than 250 F., mixing the preheated saponified material with the saponifying reagent in stream flow to effect immediate and substantially complete saponification thereof while excluding substantial quantities of air, advancing the mixture by pump pres: sure through a second heating zone and there elevating the temperature to an extent sufficient to render the soap molten when anhydrous, ad-

' vancing the resultant mixture continuously to a vapor separating zone and there continuously re moving the vaporized glycerine and removing the thus purified soap before damage thereto.

7. A process of making soap which comprises the steps of: preheating saponifiable material to a temperature above 250 F., continuously admixing a stream of said material with a stream of saponifying reagent in a zone substantially closed from the atmosphere whereby rapid and substantially complete saponification occurs while the mixture passes through said zone, continuously advancing, under superatmospheric pressure, a stream of said saponified mixture to a vapor separating zone, introducing the mixture to said zone while at a temperature sufficient to remove at least part of the vaporizable material as vapor from the soap, withdrawing the vapors and removing the soap from said vapor separating zone.

8. The process as defined in claim 7 in which the saponiflable material is preheated in stream flow and in the absence of air.

9. The process as defined in claim 7 in which the saponifiable material is preheated to a temperature above 420 F.

10. The process as defined in claim 7 in which the preheating temperature is sufllcient to cause vaporization of the vapori'zable component of the saponified mixture when the same is introduced to said vapor separating chamber.

11. The process as defined in claim '7 in which the saponified mixture is introduced at a temperature suificient to volatilize vaporizable materials therefrom and to produce soap powder.

12. The process as defined in claim 7 in which the saponifiable material is preheated while in a state of movement.

13. The process as defined in claim 7 in which substantially no heat is applied to the saponifie'd mixture and in which sumcient heat is supplied to the saponifiable material to maintain the mixture at a temperature suilicient to remove the vaporizable material as vapor from the soap upon delivery to said vapor separating zone.

14. The process as defined in claim '1 in which the pressure in said vapor separating zone is substantially less than said super-atmospheric said saponified mixture whereby the pressure is suddenly released upon discharge into said chamber, and in which sufficient heat is stored in said saponifiable material to cause at least a portion of said vaporizable material to flash into vapors upon said release, substantially no heat being supplied to said stream of said saponified mixture prior to said release.

BENJAMIN CLAYTON.

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