US3835058A

US3835058A - Process of preparing bar soap compositions and products thereof

Info

Publication number: US3835058A
Application number: US00326230A
Authority: US
Inventors: R White
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1970-12-21
Filing date: 1973-01-23
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10

Abstract

A PROCESS OF PREPARING AERATED FREE FATTY ACID-CONTAINING SOAP COMPOSITIONS HAVING UNIFORM TEXTURE, APPERAANCE AND DENSITY WHICH COMPRISES SUBJECTING AN ADMIXTURE OF SOAP AND FREE FATTY ACID, THE FREE FATTY ACID COMPRISING FROM ABOUT 0.75% TO ABOUT 15% OF THE MIXTURE, TO HIGH-INTENSITY SHEARING. THE SHEARED SOAP MIXTURE IS PROCESSED INTO BARS IN KNOWN MANNER BY COOLING, EXTRUDING, CUTTING AND STAMPING. THE REUSULTING SOAP BARS ARE CHARACTERIZED BY DESIRABLE LATHERING AND FEEL CHARACTERISTICS AND ARE UNIFORM IN SURFACE TEXTURE, COLOR AND DENSITY.

Description

slpt. 10, 1974 w E 3,835,058

PROCESS OF PREPARING BAR SOAP COMPOSITIONS AND PRODUCTS THEREOF Original Filed Dec. '21. 1970 Perfume, e1c.

Air

Confinu'bus Crurcher Coolihg and Aghufing Device INVENTOR. Ronald E. White BY a ATTOR EY United States Patent Int. Cl. Clld 9/32, 17/02 U.S. Cl. 252121 20 Claims ABSTRACT OF THE DISCLOSURE A process of preparing aerated free fatty acid-containing soap compositions having uniform texture, appearance and density which comprises subjecting an admixture of soap and free fatty acid, the free fatty acid comprising from about 0.75% to about 15% of the mixture, to high-intensity shearing. The sheared soap mixture is processed into bars in known manner by cooling, extruding, cutting and stamping. The resulting soap bars are characterized by desirable lathering and feel characteristics and are uniform in surface texture, color and density.

CROSS-REFERENCE TO RELATED APPLICATION 'This application is a continuation of my application U.S. Ser. No. 99,883, filed Dec. 21, 1970, and now abandoned.

This invention relates to a process for preparing bar soap compositions and to the bars resulting therefrom.

More particularly, this invention relates to a process for preparing free fatty acid-containing aerated bar soap compositions of desirable lathering and feel characteristics and uniformity of surface texture, color and density.

The preparation of soap bars in a more or less continuous manner by crutching soap or a mixture of soap and non-soap synthetic detergents and thereafter processing the mixture into bars, as by extruding, stamping and cutting, has been well known in the art. The preparation ofbar soap compositions having a compatible gas such as air distributed throughout and characterized by the tendency to float has also been known. The incorporation of free fatty acids into soap bar compositions for their effects in improving the quantity and quality of lather and feel-on-skin characteristics has been described in numerous patents and other literature. Bar soaps containing such acids have been referred to as superfatted bar compositions. While the advantages of the employment of free fatty acid in soap bars have been known, attempts to provide aerated soap bars having the advantages of added free fatty acid have not been entirely satisfactory. Generally, attempts to secure the desirable benefits of free fatty acid in aerated bars have been attended by the loss of one or more of the benefits or advantages characteristic of aerated bar compositions. Thus, aerated bars having sufiicient free fatty acid content to provide the known lather and feel benefits of free fatty acid have been characterized by having an undesirable surface texture and appearance. Such bars have tended to be yellowed or off-white in appearance and have been characterized by a non-uniform distribution of macroscopic andcoalescing air bubbles throughout the bar.'The result has been an undesirable increase in the density of the' bars and a generally undesirable bar or surface appearance.

It is an object of this invention to provide aerated detergent bars comprising in combination a water-soluble' alkali metal soap and a free fatty acid.

It is a further object of this invention to provide a process whereby free fatty acid-containing bar soap compositions, uniform in appearance and texture, can be prepared.

It is another object of this invention to provide a process for incorporating free fatty acid into aerated water-soluble alkali metal bar soap compositions having uniformity of texture, appearance, air dispersion and density.

Other objects of the present invention will be apparent from consideration of the invention described in greater detail hereinafter.

SUMMARY OF THE INVENTION In its process aspect, the present invention is based in part upon the discovery that aerated free fatty acidcontaining bar compositions of desirable uniformity of texture and appearance can be effected by subjecting an admixture of aerated soap and free fatty acid to high intensity shearing. The high-shear mixing thereby incorporates into the admixture a compatible gas in the form of a stable and macroscopic dispersion of non-coalescing bubbles. The resulting sheared soap mixture is then processed in known manner, as by cooling, extruding, cutting and stamping to provide bars of uniform texture and appearance.

In its product aspect, the present invention resides in the aerated free fatty acid-containing bar soap composition prepared by the aforesaid process.

DETAILED DESCRIPTION OF THE INVENTION The process of the present invention can be conveniently practiced by preparing a slurry or crutcher mix of soap, free fatty acid and water and crutching or mixing the components according to well-known soap-making procedures. This crutching operation is a normal and essential part of any soapor detergent-making process where it is desired to incorporate a number of similar or dissimilar materials into the finished product.

The crutcher mix is formulated so as to provide a semifluid and easily-pumpable homogeneous slurry. The amount of moisture or water in the crutcher mix will depend on the desired moisture level of bars prepared therefrom, the nature and relative proportions of ingredients in the crutcher, temperature and the like. A crutcher mix suitable for preparing the free fatty acid-containing soap bars of the invention will normally contain from about 20% to about 35% water, by weight.

A suitable crutcher mix for preparing bar compositions of the invention will comprise from about 40% to about preferably about 65% to about 70%, alkali metal fatty acid soap having from 8 to 18 carbon atoms; from about 0.75% to about 15%, preferably about 3% to about 7%, free fatty acid of from 8 to 18 carbon atoms; from about 20% to about 35% water; from 0 to about 20%, preferably 5% to 15%, water-soluble synthetic organic detergent; and from 0 to about 5%, preferably 1% to 4%, glycerine.

The crutcher mix is formulated at a temperature of about F. to about F. so as to keep the crutcher mix in a molten or semi-fluid and pumpable condition. The soapmixture can then be pumped while in the liquid state to-a drying apparatus, such as a conventional drum drier or vacuum flash-drier, so as to reduce the moisture content to the desired level in the finished bar composition. The soap mixture is dried to a moisture content-of from 18% to 30%. Inasmuch as the drying operation will normally involve some compacting action, the .soap mixture is dried prior to aeration.

The soap mixture is aerated by introducing a compatible gas, such as air, nitrogen, or the like while subjecting the soap mass to high-shear mixing. Sufficient air is incorporated to provide a soap mass which can be processed in bars having a density less than that of Water and which will float in water. After high-shear mixing, the soap mass is cooled, as by passage through a scraped-Wall heat exchanger or the like, and is extruded into a strip which can be cut and stamped into bars in the usual manner. I

The high-shear mixing step of the present invention can be provided by passing the soap mixture through a homogenizing valve, high-speed mechanical agitator or other high-intensity shearing device effective to provide a stable and substantially uniform distribution of microscopic and substantially non-coalescing gaseous bubbles throughout the soap mixture. Especially suited for this purpose is a dual high-speed turbine-stator mixer, commercially available as the Gifford-Wood Tandem Shear Pipeline Mixer (Gifford-Wood Inc., Hudson, N.Y.).

The precise amount of high-intensity shearing required to accomplish the objects of the invention, and thereby make possible the combined realities of aerated and free fatty-containing soap compositions of desirable texture, color and density characteristics, is not capable of accurate measurement. The suitability of a high-shear mixing device from the standpoint of the present invention can be determined by visual or microscopic examination of the finished bar composition. Suitable high-shear mixing devices provide an amount of shear effective to sufficiently shear the soap mass as to result in the formation of bar soap compositions having a bar surface free of minute surface imperfections in the nature of pits or pores which are uniform and homogeneous in texture, color and density throughout. The result is the production of bars having a smooth and uniform suface texture and uniform whiteness. A cross-section examination shows the bars of the invention to have a uniform dispersion of substantially non-coalescing gaseous bubbles of substantially uniform microscopic size.

While any high-shear apparatus capable of providing the requisite shearing effects described hereinbefore as being suitable to the attainment of the desired objectives of the invention can be employed, devices which provide an energy input of from two to five watt-hours per pound of sheared soap mass are especially suited herein. Preferably, about three to four watt-hours per pound are employed.

The high-shear mixing of the present invention is effected on an aerated soap mass. Thus, the soap mass is aerated prior to or simultaneously with the application of the high-shear mixing described hereinbefore. Partial or complete aeration can be effected prior to shearing. Preferably, from the standpoint of convenience, the soap mixture and high-shear mixing step are effected simultaneously. The aeration of a soap mix which has a free fatty acid content and which has been previously subjected to high-shear mixing will not provide bar soap compositions having the desirable uniformity of texture, appearance and density that is obtained in accordance with the practice of the present invention. Accordingly, high-shear mixing of a soap mass'previously or simultaneously aerated is believed to be material to the attainment of the objectives of the invention.

The alkali metal soap components suitable foruse in the'process of the present invention include any of the water-soluble soaps normally used in bar soap processing. These include the sodium and potassium soaps of higher fatty acids or mixtures thereof. The sodium soaps, particularly those derived from mixtures of coconut and tallow oils are preferred. Water-solublesoaps made fro-mother fats or fatty acids can also be used as will be evident to those skilled in the art.

4 I The soaps of the present invention will normally con: tain from 8 to 18 carbon atoms. Commercial soaps preferred herein are generally based upon mixtures of fatty acids obtained from various natural sources. Coconut oil, for example, is a materialwhich has found considerable use in high-quality soap compositions. Similarly,tallow is a useful source of high-quality soaps. Other suitable sources include palm kernel oil and babassu kernelgioil which are included within the term ""coconut oilff olive oil and synthetic fatty acids simulating, for example, tal; low. Particularly useful herein are'the-sodium and 'potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap. Preferred soap mixtures are the tallo'w/ coconut soaps ranging in proportions from :30 to 50:50 by weight. These soap mixtures are preferred from the standpoint of ready availability, ease of processing and their desirably optimum physical and performance characteristics. 7

The term coconut as used herein in connection with soap or free fatty acid mixtures refers to materials having an approximate carbon chain length distribution of:"8% C3; C10; C12; C14; C16; C13; oleic and 2% linoleic (the first six fatty acids: being saturated). 1 1 The term tallow as used herein refers'to a mixturue of soaps having an approximate chain-length distribution of: 2.5% C 29% C 23% C 2% palmitoleic; 41.5% oleic acnd 3% linoleic (the first three fatty acids being saturated). i

The fatty acids which can be used in the process of the invention are those having from 8 to 18 carbon atoms. Normally a mixture of. free fatty. acids derived from natural sources is employed. Preferred mixtures of fatty acids are the coconut/tallow fatty acid mixtures herein before described. I

The fatty acids improve the quantity and quality. of the lathering characteristics of bars prepared in accordance with the process of the present invention. The ad: vantage of free fatty acids in tending to provide a lather of desirable stability and having small air bubbles so as to provide a rich or creamy lather has been known inthe art. Fatty acids also provide an emollient effect which tends to soften the skin or otherwise improve feel-on-skin characteristics.

The amount of fatty acid incorporated into the finished bars of the invention ranges from about 1% to 15%. Below about 1%, the desirable advantages described herein-.- before are not readily apparent. Amounts greaterthan about 15% provide little further benefit without corresponding economic advantage. A preferred amount. of fatty acid ranges from about 3% to about 7%. r The free fatty acid can be incorporated into bars of the present invention in a number of suitable ways. The free fatty acid component is desirably incorporated into the soap mixture either prior to or simultaneously with the high-shear mixing step described hereinbefore. .Uni form distribution of the free fatty acid throughout the finished bar composition is facilitated by thehigh-shearing action. The free fatty acid component can be addedsubsequent to the high-shear mixing step if other subsequent mixing means are employed so as to substantiallyuniformly distribute the free fatty acid throughoutthe soap mixture or resulting bar composition. I f The free fatty acid componentis preferably inti oducd into the soap mixtures of the present invention by addi tion of thefre'e fatty a'cidfto the soap fmixture in the initial crutching stage. Alternatively, the free fatty acid component can be introduced prior to or during thejaeral tipp stage where perfume and other additives, if desired, are incorporated into the soap mixture. The-free. fatty, acid component can also beintroduced as a prepared mixture of soap and free fatty acid, such as an, acid-reaCtlng.- f X-. ture of soap and free fatty acid prepared by-. under neutralization in the soap-making process.

The bar soap compositions of the present invention can contain other additives commonly included in toilet bars such as perfumes'isanitizing or antimicrobial agents-',1dyes, andfltheIli-kefThese additives make thefinished bar com positions either more attractive or effective withoufdetractin'gfronithe desirable attributes of the bare The bar compositions of the'p'resent invention can additionally' contain a water-soluble organic" non-soap synthetic detergent. Normally the soap/ synthetic bars are prepared to contain a ratio of 'soap'to synthetic detergent of from 35 1 to 9:1. Ihelc'hoiceof suitable ratios will depend uponthe-particul'arsynthetic detergent, the desired performance and physical characteristics of the finished bar, .temperature,,moistureand like processing considerations. preferred ratio is from 5:1 to 7: 1.

Thesynthetic' detergent constituent of the bar'compositions of the invention can be designated as being a det'ergent from-the class 'consisting of anionic, nonionic, airi'pholytic and zwitterionic synthetic detergents. Examples of suitable synthetic detergents for use herein are those described in-U.S.;Pat..3,35l,558 (Nov. 7, 1967) at column 6, line 70 to column 9, line 74, incorporated herein by reference. v

Preferred-herein are the water-soluble salts of organic, sulfonic acids and of aliphatic sulfuric acid esters, that is, water-soluble salts ofprganic sulfuric reaction products having in the molecular structure an alkyl radical of from 10 to 22- carboii atoms' and a radical selected from the group consistingqo'f sulfonic acid and sulfuric acid ester radicals. n- 't' Synthetic-,sulfate .detergentsof special interest are the normallyzsolid alkali metal salts of'sulfuric acid esters of normal primaryialiphatic alcohols having from 10 to 22 carbon atoms. Thus, the sodium and potassium salts of alkyl sulfuric acids-obtained from the mixed higher alcohols derivedby the reduction of tallow or by the reductioriof coconut oil, palm kernel oil, babassu kernel oil or other-oils of the coconut group can be used hereinQ :r-Other aliphatic sulfuric'acid esters which can be suitably employed include the water-soluble salts of sulfuric acid esters of polyhydric alcohols'incompletely esterified with high. molecular lweight soap-forming carboxylic acids. Such synthetic' detergents include the Water-soluble.alkali metal} salts of sulfuric'acid esters of higher molecular weight fatty acid monoglycerides such as the sodium' and potassiumsalts of the coconut oil fatty acid mono'ester of 1,2 'hydro'xypropane-3-sulfuric acid ester, sodiumand potassium monornyristoyl ethylene glycol sulfate, and sodium and potassium r'nonolauroyl diglycerol sulfate. a I *f Preferred sulfonate detergents include the alkyl glycerylethel"sulfo'nate detergents (i.e;, water-soluble salts of alkyl glyceryl ether sulfonic acid) having from 10 to 18 carbon atoms in the alkyl group. These sulfonates provide thebars of the invention with desirable lime soapor scum-dispersing properties and can be conveniently pfoces's'ed to provide soap/synthetic bar compositions having the desirable uniformity of texture and appearaiicdescr'ibed hereinbefore. Preferably, they comprise from about 5% to 15% of the finished barcompositio'n s. 1l 1es esulfonates canbem ade by first reacting fatty alcohols with epichlor'ohydrin and then reacting the alkyl chlorg fglyceryl etherssoffofimed with sodium or potassium 's'ul fites. ,The 'pre'jfe'rredisourc of the fatty alcohols which are used in' the foregoingreaction is coconut oil 'and" like "l hols. The "alkyl glyceryl'ether sulfonates" are described detailin'fILSjPat. 2,989,547 (June 20,1961). 'lu addition to the incorporation ofjminor amounts of materials? to improve fcolorjodor or theli ke,.is the additioif of from tip to about 5% 'glyce'rine byflweight of the finished bar composition, A preferred arnount'is from about "1% to :about 4%; The in'corporationof glycerine into a Soap mixtui'e materially aids the processing' of .bar soap corripositionsflt has been found that the incorporation of glycerinelin the initial crutchenm ix facilitates processingby making the soapmass more readily-pump able and easily handled.'The soap mass is rendered less sticky, thereby facilitating processing.by avoidanee of sticking of the rnass on processing equipmengsuchas m xers. x rfi er sr p s n belts. and the i T v elm-1 ployment of glycerine, thus, constitu tes a preferred practice of the present invention...

. Although not limitedthereto, this invention has been found to .be particularly applicabletand.beneficial .in-the preparation of a floating, aerated, detergent bar, consisting essentially of; about 65% of a water-soluble soap, a 1:1 mixture ofsoap coconut and tallowrsoaps; about 10% of a sodium alkylglyceryl ether sulfonate, wherein the alkyl group is derived from the middle-cut fatty alcohols obtained from coconut oil; about 3% glycerine; from about 1.0% to about 1.5% of sodium chloride; and about 21% moisture. The middle-cut coconut alcohols are derived from the coconut oil fraction having the following approximate composition: C 2%; C 66%; C ,23%; C 9%.

The following examples illustrate the practice of this invention. All percentages, parts and ratios herein are by weight unless otherwise specified. Reference is made to the Figure which shows diagrammatically the various component parts of an apparatus which can be used in the process of the invention.

EXAMPLE I 102 parts of sodium soap (a 50/50 mixture of sodium coconut oil soap and sodium tallow soap, having about 30% moisture and about 0.5% sodium chloride) was supplied in molten condition to crutcher l'along with 7.0 parts free fatty acid derived from coconut oil. The soap/fatty acid mixture, maintained at a temperature of about 185 F. in the crutcher was pumped by pump 2 to heater 3, wherein the soap mixture was heated to about 325 F. The heater 3, conforming in structure to known types of heat exchange devices for raising the temperature of liquids, was a shell and tube exchanger permitting the fiow of the soap/fatty acid mixture through the tube and supplied with high-pressure steam in the outer or shell side. The steam pressure was such that the mixture discharged from the heat exchanger was 325 F. The hot soap/fatty acid mixture was sprayed through spraynozzle 4 into flash chamber 5.

Following the reduction of moisture content of the soap/fatty acid mixture in the flash chamber 5 to about 21.5% by weight of the crutcher mix, the flash-dried mixture was conveyed by pump 6 to and through a continuous crutcher 7 where air, perfume and other additives were incorporated into the mixture, and then to a highshear mixer 8 where it was subjected to a high-shear stress of about 3.4 watt-hours per pound of the mixture. The high-shear mixer 8 has a tandem high-speed mechanical agitator, commercially available as the Gifford-Wood Tandem Shear Pipeline Mixer. The sheaied mixture was conveyed to acooling device 9, which was of the type more fully described in Mills patent, US. 2,295,594 (Sept. 15, 1942). The mixture was cooled and agitated and was finally extrudedin' acontinu'ous strip through outlet orifice 10, at a temperature of about 145 Fjomo a traveling conveyor belt -113" The' continuous stripwas then separated into individual bar lengths'by the cutter indicated schematically at 1 2 g t r V Qn'examination, the bars were found to b'e 'very. white and uniform in' 'texture. The air bubbles wefe distributed uniformly throughout thebar' ina finely dispersed state. The air bubbles were microscopic imsize. p The indiv idualbar lengths were. then cooled under controlled conditions of temperature and humidity the humidity being controlled at about relative humidity to 'prevent the bars from drying duringcooling and the temperature of the ambient cooling air being controlled at about 75 F Underthese conditions, the .terriperature of the individualbar lengths remained in a temperature 7 r'an'ge' of' about-110 'Fi'to about 120 FQfor less thanlS mihUtS. z ai l-Z Bars ':of soap were prepared usingt'he materials and apparatus described in"Example"I except that no 'highshe'armixing"- was employed." Th'eiuaterials and propor tio'ns wereas described 'inE'xampie I. Bars were prepared by either by-passing the high-shear mixing (it bypassing the soap mass"through an"i'nopeirative mixer. Both instances resulted in the preparation of bars having variations "indensity and noticeably-poor' 'air dispersion: The air dispersion was observed to be non-uniform and*com prised a dispersion of air bubbles of substantially-varying sizes. The poor-quality air dispersion was readily apparent to the unaided eye. The bars were also characterized by a yellow appearance when compared to the whiteness of the bars prepared in accordance with Example I of the invention.

EXAMPLE II The apparatus and procedure of Example I was employed in the present example except for the following. A 70/30 mixture of tallow and coconut sodium soaps was employed. An amount of about 3% coconut free fatty acid was employed but was introduced immediately prior to the high-shear mixer 8. The following process conditions were employed:

Temperature of soap out of heat exchanger F.) 317 Final soap moisture (percent) 20.5 Amount of sheartwatt hours/lb.) 3.0 Strip extrusion temperature F.) 150 Examination of the resulting bars showed the surface texture to be smooth and uniform. The color was white and uniform. The bubbles were uniformly distributed and microscopic in size. The density of the resulting bars was uniform. I

Soap bars were prepared in the same manner as those in Example II except that no high-shear mixing was employed. Inspection of the resulting. bars showed the surface texture to be unsmooth and non-uniform. The, bars were slightly yellow and non-uniform in color. The air bubbles were non-uniformly distributed and of sufi'icient size as'to be visible to the human eye. The density of the bars was variable.

EXAMPLE III Soap bars were prepared in the manner described in Example I. The following composition was supplied to crutcher 1: I

Components: Parts by Weight 50/50 mixture of tallow and coconut soaps 55 Water 35 Sodium chloride 1 Sodium middle-coconut-alkyl glyceryl ether sulfonate l2 Coconut-alkyl fatty acid 7 Glycerine 4 The following processing conditions were employed: Temperature of soap out of heat exchanger- F.) 320 Final soap moisture (percent) 19 Amount of shear (watt hours/lb.) 4.1 Strip extrusion temperature F.) -c :155

s' .EXaMRL fW 3;"-

r as 'na s;

des r b s in Exam ep th t rt swi rs ppl s io tc ls r: Components Rams y-weight 50/50,, mixture of. tallow and coconut-alkylsoig I dium soaps Water as I Sodium h i s i m i cs uiyq t e fonate a...

V Coconut-alkylfree iatty acidg The following processing conditions' were employed Temperature of soap out ofhe atexchanger Final soap moisture (percent) Amount of shear (watthours/lb.) Q Strip extrusion temperature F.)

Examination of the resulting .bars' showed th'e bars "to be smooth in surface appearance w itlr some stickiness and bar surface cracking. The resulting bars were try white and uniform in appearance. Air bubbles were m roscopic in size and uniformly distributed/Ehe den the bars was also uniform.

EXAMPLE Soap bars were prepared .inthecmanner described "in Example IV except that threeparts of 'glycerine we: nin cluded in the mixture charged to crutcher 1. I.

The resulting bars exhibited theJsamedesirable:characteristics of the bars of Example IVgexcept-rthat-there was no apparent stickiness or -surface ;cracking;;

What is claimed is:

1. A process for preparing an -aer;ated-.free-.;fatty acidcontaining soap composition which comprises-.the. steps of. preparing at a temperature offrom about .1'40=.F.to about 190 F. a soap mixture.consisting.essentially of from about 40% to about 75% of an alkali metalufatty acid soap having from 8- to 1.8 oarbon-atoms,.-from about 0.75% to 15%- of a free fatty acidhavingjfrom -8. to..'l8 carbon atoms and frorn l8% to 30%:water; as iiting'the soap mixture by introducing a. Compatible gas". in. an amount sufficient to provide a soap, mass h'avingUa density less than that of water; and shearing the-raerated;mixture with sutficient high-shear mixing to1incorp'0rate. the com; patible gas into the soap mixture in the form. -.of;,sub;- stantially uniformly distributed microscopic and substan-v tially non-coalescing bubbles. I H

2. The process of Claim 1 wherein the soap is a mi of sodium coconut and sodium tallow soaps.. g.

' thefree a 3. The process of Claim 2 wherein is a mixture of coconut .fatty acids.

ing corresponds to from: 2.0 to watt hours per pound of soap mixture.

5. The process of Claim 1 wherein thestep's other and shearing are eir'ectedsimultaneOuSIy. 2

6. The process of Claim 1 wherein the compatib'l is air. v 7. The process of Claim 1 wherein the soap mixt, prepared by providing a compositi onconsisting essen (I of from about 40% to 75% of an jalkalilfrnetal fatty soap of frOm'S to -18,carbon atoms; from about toabout' 15% free "fatty acid havingj ff rom' "8. to lh car atoms, from about j'20%i tot about 3 5 %.fwate about 20% of a'fwater- 'soluble s'y'nthe and from 0 to about 5% glycer n I y I moisture content thereof prior to aeration and mixing by drying to wiinnime'raa of to about 30% 9 carbon atoms and is present in an amount of from about to about 10. The process of Claim 7 wherein the soap mixture is aerated with sufiicient air to provide a floating soap mass having a density lower than that of water and the amount of high-shear mixing corresponds to about 2.0 to about 5.0 watt-hours per pound of soap mixture.

11. The process of Claim 7 wherein the aerated and sheared soap mixture is cooled, extruded and cut and stamped into soap bars.

12. The process of Claim 1 wherein the soap mixture is prepared by providing a soap composition consisting essentially of from about 65% to about 70% of a mixture of sodium coconut and tallow soaps; from about to about water; from 3% to 7% coconut free fatty acid; from 5% to 15% sodium coconut-alkyl glyceryl ether sulfonate; and from about 1% to 4% glycerine; and reducing the moisture content thereof by drying to within the range of from about 18% to about 30%.

13. The process of Claim 12 wherein the soap mixture is aerated with sufiicient air to provide a floating soap mass having a density lower than that of water and the amount of high-shear mixing corresponds to about 3.0 to about 4.0 watt-hours per pound of soap mixture.

14. The process of Claim 12 wherein the aerated and sheared soap mixture is cooled, extruded, cut and stamped into soap bars.

15. An aerated free fatty acid-containing soap composition consisting essentially of from about to about of an alkali metal higher fatty acid soap having from 8 to 18 carbon atoms; from about 0.75% to about 15% free fatty of from 8 to 18 carbon atoms; from 18% to 30% water; from 0 to about 20% of a watersoluble organic non-soap synthetic detergent; from 0 to about 5% glycerine; and a compatible gas in an amount sufiicient to provide a density of the composition less than that of water; said compatible gas being present in the form of substantially uniformly-distributed microscopic and substantially non-coalescing bubbles.

16. The composition of Claim 15 wherein the soap is a mixture of sodium coconut and sodium tallow soaps.

17. The composition of Claim 16 wherein the free fatty acid is a mixture of coconut fatty acids.

18. The composition of Claim 15 wherein the ratio of soap to synthetic detergent is from 3 :1 to 9: 1.

19. The composition of Claim 18 wherein the synthetic detergent is an alkali metal alkyl glyceryl ether sulfonate where the alkyl has from 10 to 18 carbon atoms and is present in an amount of from about 5% to about 15% 20. The composition of Claim 15 wherein the glycerine is present in an amount of from about 1 to 4%.

UNITED STATES PATENTS References Cited 3,481,880 12/1969 Austin et al 252539 3,494,869 2/1970 Armstrong 252,-Dig #16 3,089,197 5/1963 Chatfee et al 252370 WILLIAM E. SCHULZ, Primary Examiner US. Cl. X.R.

252-l74, Digest #16