US2820768A - Soaps and their methods of preparation - Google Patents

Soaps and their methods of preparation Download PDF

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US2820768A
US2820768A US53125755A US2820768A US 2820768 A US2820768 A US 2820768A US 53125755 A US53125755 A US 53125755A US 2820768 A US2820768 A US 2820768A
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soap
triethanolamine
fatty acid
acid
soaps
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Fromont Louis Edmond Ge Hubert
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    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D9/00Compositions of detergents based essentially on soap
    • C11D9/04Compositions of detergents based essentially on soap containing compounding ingredients other than soaps
    • C11D9/22Organic compounds, e.g. vitamins
    • C11D9/30Organic compounds, e.g. vitamins containing nitrogen
    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D1/00Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
    • C11D1/38Cationic compounds
    • C11D1/46Esters of carboxylic acids with amino alcohols; Esters of amino carboxylic acids with alcohols
    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D10/00Compositions of detergents, not provided for by one single preceding group
    • C11D10/04Compositions of detergents, not provided for by one single preceding group based on mixtures of surface-active non-soap compounds and soap
    • C11D10/047Compositions of detergents, not provided for by one single preceding group based on mixtures of surface-active non-soap compounds and soap based on cationic surface-active compounds and soap
    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D17/00Detergent materials characterised by their shape or physical properties
    • C11D17/0095Solid transparent soaps or detergents
    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/16Organic compounds
    • C11D3/26Organic compounds containing nitrogen
    • C11D3/30Amines; Substituted amines ; Quaternized amines
    • CCHEMISTRY; METALLURGY
    • C11ANIMAL AND VEGETABLE OILS, FATS, FATTY SUBSTANCES AND WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11DDETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D9/00Compositions of detergents based essentially on soap
    • C11D9/002Non alkali-metal soaps

Description

In E Q ggg td assures Patented Jan. 21, 1958 2,820,768 SOAPS'AND TIER WTHUDS (3F PREPARATION Louis Edmond Georges Hubert Fremont, Molenbeek St-iiean, Belgium N Drawing. Application August 29, 1955 Serial No. 531,257 Claims priority, application Belgium May 13, 1952 3 Claims. (Cl. 252118) The present application is a continuation-in-part of copending application, Serial No. 298,833, filed July 14, 1952 (and abandoned since the filing of the present application) This invention relates to an improved soap which is obtained in solid form suitable for toilet use and to the preparation of the same.

It is well known that the conventional alkali metal soaps in current use for toilet purposes are alkaline, that is to say their water solutions show a pH value of at least 9.5. Such soap water solutions assume a red color in the presence of a few drops of phenolphthalein solution, which indicates the presence of free alkali metal ions. Even soaps free from sodium or potassium carbonate have an alkaline reaction and the pH value of their water solution is never below 8.5. If products such as lanoline are incorporated in these soaps with a view to producing so-called super-faded soaps, the pH value of such soaps is not modified to any material extent and remains appreciably high.

It has been found that conventional alkali metal soaps, owing to the presence of free alkali metal ions in their aqueous solutions, react with ordinary and complex amino-acids, such as the keratin of the skin, hair and nails, to replace the amino groups of these acids by alkali metal atoms or to form addition products. Said reaction tends to impair the chemical and biological properties or" such amino-acids.

Furthermore, according to recent research findings by Macheboeuf and Robert at the Institut Pasteur of Paris, keratin, like every protein containing cystin in its molecule, is apt to absorb oxygen from the air when placed in a medium having a pH value equal to or above 9.5, such as that provided by water solutions of alkali metal soaps. Once started, this reaction proceeds even after the environment is no longer alkaline. In this way also, therefore, the contact of the skin with water solutions of alkali metal soaps causes the keratin to lose its chemical and biological properties.

The consequence of both detrimental effects above mentioned is a desquamation of the injured surface layers, which is conducive to shriveling and wrinkling the skin and matting and felting the hair.

It is also known that the epidermis has the power of secreting fatty materials which are acid or become acid by auto-oxidation, as is the case with sebaceous fats. By accumulating upon the skin such acid secretions may cause physiological inconveniences, amongst which are objectionable body odors. The action of conventional alkali metal soaps on such secretions is limited to emulsifying the fatty acids contained therein, whilst at the same time they are partially decomposed themselves with liberation of their own fatty acids. These in their turn react with the calcium and magnesium salts of hard water to form insoluble soaps which deposit on the part that is being washed, for example on the skin or in the hair, and on the container used for the washing operation,

for example baths, sinks and the like. Thus the use of conventional alkali metal soaps does not enable the skin to get entirely free from fatty acids, which leave a slight rancid smell upon it.

It is further known that lower molecular weight fatty acid soaps, such as cocoa-nut soaps, have an irritating effect upon the skin owing to the exceedingly penetrative power of their molecules into pores and between cellular sheets, while higher molecular weight fatty acid soaps, such asstearic acid soaps, are comparatively kind to the skin and mucous membranes.

Finally, it has been found that the detergent and dis.- solving power with regard to the skin of alkaline combinations commonly used with soap compositions decreases according to the following series: sodium hydroxide, sodium carbonate, ammonia, monoethanolamine, diethanolamine, triethanolamine, triethanolamine soaps being substantially without any detrimental eifect upon the skin.

It is the primary purpose of this invention to provide an improved soap in solid form which possesses more favorable properties with respect to the skin than do conventional alkali metal soaps and which is free from, or offers in lesser degree, the above mentioned disadvantages of known soaps.

It is a further object to provide an improved hard and transparent soap which is substantially non-alkaline, has excellent but harmless detergent action and is capable of neutralizing a substantial quantity of an acid andof a base Without its foarning power and its pH being affected.

I have found that a soap with advantageous properties can be obtained by mixing a transparent alkali metal soap with the product of the reaction of a soap-forming fatty acid having no less than 18 carbon atoms with triethanolamine in excess, that is more tricthanolamine than required to fully neutralize said fatty acid in form of a salt thereof, the proportions of ingredients and the reacting conditions being controlled to obtain a hard, transparent, substantially non-alkaline soap. To produce a mixed soap having the characteristics above mentioned, it is essential thatthe proportion of tricthanolamine employed should be no less than two mols, but no more than three mols per mol of soap-forming fatty acid, the preferred ratio of triethanolamine to fatty acid being-2.5 mols of triethanolarnine to one mol of fatty acid.

According to this inventiomtherefore, I provide a mixed, hard, transparent soap comprising essentially a transparent alkali metal soap, a triethanolammonium salt of a soap-forming. fatty acid having no less than 18 carbon atoms, and an excess quantity of triethanolamine equal to at least the stoichiometric quantity of triethanolamine combined with said fatty acid in form of a salt thereof and to-at most twice said stoichiometric quantity, said mixed soap having a pH value of approximately7;5 in 10% aqueous solution and being capable of neutralizing a substantial quantity of an acid and of a base without its foaming power and its pH being affected.

The improved mixed soap embodying this invention may be made in the following manner: one molecular proportion of a soap-forming fatty acid having no less than 18 carbon atoms is mixed with between two and three molecular proportions of triethanolamine and with the desired quantity of a transparent alkali metal soap. The mixture is heated at a temperature withinthe range of-l20 C., preferably C., until the reaction is complete, that is until the mixture exhibits a homogeneous transparency which is maintained on cooling'and a pH value of approximately 7.5 in 10% aqueous solution. The-"duration of the period of heating; varies to neutralize both acids and bases.

proper point indicated above.

dispersing agents "The'y invariably show' an alkaline pH which is recognized inversely with the temperature, but it is imperative to stop heating when the reaction has proceeded to the proper point indicated above. Theperiod of heating may be readilydetermined. for any particular mixture by simple preliminary experiments. to ascertain whether 'theprodnot obtained after any particular period .of heating complies with thevtwo criteria setout 'above.. The product obtained is a mixture of a transparent alkali metal soap with a triethanolamine' fatty acid soap andan excess triethanolamine amounting to between one and two. molecular proportions per molecular proportion of fatty acid combined in the triethanolamine fatty acid soap. The proportion of alkali metal soap in the mixture should be so chosen that the product has the required characteristics in addition to complying with the criteria mentioned above, that is the product should be sutficiently hard and transparent.

I have found that if thefinal product contains at most I 60% of transparent alkali metal soap, very good results are obtained.

According to a feature of this invention, I provide a process for the preparation of a mixed, hard, transparent soap, which comprises mixing a soap-forming fatty acid having no less than 18 carbon atoms with at least two and at most three molecular proportions of triethanolamine per molecular proportion of said fatty acid, and with a transparent alkali metal soap, and then heating the mixture at a temperature within the range of 100- 120 C. until it exhibits a homogeneous transparency which is maintained on cooling and a pH value of approximately 7.5 in 10% aqueous solution.

I am aware that it has been'previously proposed to manufacture soaps from triethanolamine and fattyacids, and more particularly triethanolamine-fatty acid soaps of the type containing an excess of free triethanolamine, and that it has been suggested to incorporate such soaps in alkali metal soaps to produce mixed soaps. Examples of such prior proposals are found .in the Hoyt Patent 1,833,899 of December 1, 1931, Harvey Patent 1,828,736 of October 27, 1931 and Ulrich Patent 1,935,217 of November 14, 1933. The known processes for preparing such mixed soaps exemplified in the above specifications, result, however,-in reaction products which are substantially different from my improved soap, owing mainly to the fact that the prior workers fail todisclose or to suggest theamounts of triethanolamine as are'set forth in this invention. and particularly fail to show the importance of the maximum amount which is essential in order to obtain a mixed soap having the peculiar properties of my improved soap. If the ratio of triethanolamineto fatty. acid is below the lower limit specified above, the product obtained is not transparent and unable If the ratio of triethanolamine to fatty acid is above the upper limit specified above, the resulting product has too soft a consistency and contains free triethanolamine which raises its pH value to a pointwhichrenders the product detrimental to the skin. Further, none of the prior workers suggests the peculiar reacting conditions employed in this invention, and particularly the essential importance of withdrawing heat when the reaction'has proceeded to the if higher temperature and/or longer periods of heating are employed, excessive quantities'of water are split out of the mixture, which tends to eliminate the soap addition product from the reactionmixture and is conducive to condensation derivatives which do'not exhibit the properties inherent in the improved soap according to this invention.

It'must also be pointed out that the products of the prior proposals are intended principally for use as improved detergents'suitable as cleansing, emulsifying and for the textile'andrelated industries.

as imparting a substantial improvement to their activity "for such purposes, but renders them essentially difierent from my improved soap and admittedly unsuitable for toilet purposes for the reasons" set out above.

It should further be emphasized that in one of the prior proposals it is stated that a triethanolamine-fatty acid soap containing an excess triethanolamine can have a pH value of approximately 7.5. When it is known that triethanolamine-fatty acid soaps, if fully neutralized, have a pH value of about 8, and that if mixed in small proportions with alkali metal soaps they tend to bulfer their alkalinity, such small quantities, and even largerones, could hardly be expected to' lower the pH value of the mixed soap to approximately the neutral point.

Finally it is well worth mentioning that the prior teachings fail to disclose the factithat the product is capable of neutralizing a substantial quantity of an acid and of a base without its foaming power and its pH being affected. Triethanolamine-fatty acid soaps or mixed soaps according to prior proposals are destroyed by acid, while my improved soap is not, and are unable, having an alkaline pH value, to neutralize bases, while my improved soap possesses this peculiar feature. a h

- I believe that the ability to neutralize both acids and bases while having a practically neutral pH value is peculiar'to', my improved soap and is due to the peculiar ratio of triethanolamine to fatty acid and reaction conditions employed in making such a soap. It is assumed that both special features above mentioned are due to the excess triethanolamine being combined with the triethanolammonium salt of mine the exact nature of thejproduct which I obtain. While the mechanism of the reactions which take place is exceedingly complex, present indications point to the probability that such an ether is formed. It is my present view that the mechanism of the reactions as indicated hereafter represents possibly the most reasonableqexplanation of what occurs in the process and of the special features of my improved soap. I do not, however, wish to be bound by these statements since may more definitely fix the nature of the reaction product of this invention. Thus while I do not wish to be limited by theroetical explanations, I provide the following equations as an illustration of the probable chemical composition of my improved soap and of what occurs in the 7 process for its preparation. In these equations R rep resents an aliphatic group having at least 18 carbon atoms.

i When the fatty acid is heated with triethanolamine,

a triethanolamrnonium'salt of said fatty acid is probably first produced:

- o 'onlornon onlornon (1 fatty acid triethanolarnrnonium triethanolammonium salt hydroxide of fatty acid 1 1 CHaCHiOH RCOON-CH2CH:OH 12-00011 CHaCHzOH H CHzCHnOH Mono-fatty acid ether of trlethanolammonium salt qfiettyecid.

fatty acid in form of an ether thereof. I have found it impossible up to the present timeto deterfurther 1 research H CH2CH2O 0-18 R-COON-CHaCHsOH di-fatty acid ether of methanolammonium salt of fatty acid Said jelly then dissolves in the excess triethanolamine and products of the following probable formulae are believed to result according to the molar excess of triethanolamine present in the mixture:

H CHzCHsOH H CHzCHzOH R-COON-CH2GH2OH N-CHgCHgOH CH2CH;OOCR 0H CHaCHaOH H CHsCHzOH R-COON-CHzCEbOH R-COOH H1O CHzCHnO CHzCHz (A) HO CHzCHz-N HO CHzCH:

H CHgCHzOOCR H CHzCHgOH RCOONCH2OHzOH +2N-CH2CHzOH CHzCHaOOC-R O CHzCHzOH HOCHzCHg HOCH:CH2N

H CHzCHzOCHzCH:

R-COON-CHzOHnOH CHQCHnOCHzCH:

HOCHaCHQ-N HOCHzCH:

The Products A and B may be referred to as triethanolammonium ethers of triethanolammonium salt of fatty acid. Their pH value in aqueous solution has been found equal to approximately 7.5, thus close to neutrality. The pH of the products is in no way affected by the presence of the fatty acid (RCOOH) liberated, since said fatty acid at once reacts with further triethanolamine, as exemplified in Equation 1.

I have found that products of the probable Formulae A and B have too soft a consistency to be used as toilet soaps, but I have discovered that a hard, transparent soap which retains its shape and is quite suitable for toilet purpose may be obtained by preparing the Products A and B in the presence of a transparent alkali metal soap, that is thoroughly mixing a transparent alkali metal soap with the starting materials. The resulting mixed soap exhibits physical and chemical properties different from those shown by each of its components taken separately.

With regard to its physical properties, the mixed soap is transparent and of such a hard consistency that it can hardly be cut with a steel wire, while sodium soaps are hard but are out quite readily with a steel wire and soaps of the Formulae A and B are of soft consistency. Further, the mixed soap melts at about 60 C. while sodium soaps do not melt.

With regard to its chemical properties, tests have shown that the pH value of the mixed soap in 10% aqueous solution is substantially neutral while the pH value of a 10% aqueous solution of a sodium soap is about 9.5. To account for this, it is believed that the mixed soap has a chemical structure similar to that of alums and miscellaneous complex salts known in inorganic chemistry. In fact, large molecules appear to be formed in the reaction mixture by adsorption between one mol of the Product A or B and one mol of alkali metal soap. This 2R-COOH H2O 'kind of linkage occurs with alums, and it is believed that t e mixed soap may be represented by the following for-' mulae, in which R is an aliphatic group containing no less than 18 carbon atoms:

R-COONa H CHzCHzOH RCOON-CH2CH2OH CHzCHzO CHzCHz HOCHzCIh-N HOCHQOHQ R-COONa In aqueous solution, the alkali metal soap is ionized, but the free RCOO- and Na+ ions are believed to be neutralized respectively by the basic (amine) functions of the nitrogenous groups and by the free hydroxyl groups of the combined triethanolamine. The pH value of the mixed soap thus remains'close to neutrality.

It can be seen from Equations 4 and formulae 5 that the excess triethanolamine in the mixed soap must not theoretically exceed the 3 mols of triethanolamine capable of combining with the free hydroxyl groups of the tri ethanol-ammonium salt of fatty acid in form of ethers thereof, as otherwise the final product would contain an excess of free triethanolamine and its pH value would rise abruptly to about 11.5, which represents the pH value of free triethanolamine. In practice, however, the excess triethanolamine combined in form of ether should not exceed 2 mols, as I have found that a triethanolammonium salt of fatty acid having its three hydroxyl groups etherified with triethanolamine is already too alkaline (pH=9.5) to achieve the essential object of the pres ent invention.

The following tests will illustrate the ability of my improved soap to neutralize both acids and bases.

A few drops of an acid, for example dilute hydrochloric acid, are smeared on the hand and 2 drops of methyl-orange indicator are added thereto: the hand assumes a red color due to the acidity of the medium. If lather derived from my improved mixed soap is applied to the hand, the red color disappears, giving way to a yellow color, which indicates that the soap has neutralized the hydrochloric acid. A further characteristic feature of the mixed soap wish this test illustrates is that no fatty acid is liberated, which can be seen from the absence of sticky film on the hand, and that the lather persists. If the same test is carried out with dilute caustic soda and a few drops of phenolphthalein solution as indicator, the hand first assumes an intense red color due to the alkalinity of the medium. If the lather of my improved soap is then applied to the hand, the red color disappears and the hand turns colorless, which indicates that the soap has neutralized the caustic soda.

A further illustration is shown by tie following experiments: in a glass tube, 1 gram of my improved soap is dissolved by means of heat in 9 gm. of distilled Water and a few drops of methyl-orange are added thereto, whereby the contents of the tube assume a dark yellow color. If a 10% hydrochloric acid solution is then allowed to flow drop by drop into the tube, the red color first produced immediately turns yellow again on shaking the tube, which indicates that my improved soap has 1 neutralized the acid. More than 10 drops of hydrochloric I is required to produce 7 Soap is capable of neutralizing a substantial q'uantityof an acid. In a glass tube (tube 1), 1 gram of my improved soap is dissolved in 9 gm. of distilled water and a few drops of phenolphthalein solution are added thereto: the contents of the tube remain colorless, which indicates a pH value close to neutrality, i. e. below 8. In another glass tube (tube 2), 1 gm. of any known toilet soap is dissolved in 9 gm. of distilled water and a few drops of phenolphthalein are added thereto: the contents of tube 2 exhibit a red color, which shows a pH value of about 9 to 10. Part of the contents of tube 2 is then poured out into tube 1: on shaking tube 1 the red color disappears, which indicates that a 10% water solution of my improved soap is not only substantially neutral, but further capable of neutralizing Further, a few drops of phenolphthalein solution are run gently along the inside walls of tube 1 and then a sodium hydroxide solution is allowed to flow drop by drop into the tube: an intense red color first appears due to the contact of caustic soda with phenolphthalein. Upon shaking the tube, however, the red color immediately disappears, which indicates that my improved soap has the power of neutralizing a substantial amount of a base. If additional caustic soda solution is added drop by drop into tube l,'it is observed that a substantial excess-of base a reddishvcolor. If, however, as little as one drop of caustic soda solution is added to tube 2, the red tint does not disappear, but is intensified, which indicates that alkali metal soaps basic media.

My improved soap, which may be referred to as neutrogenous, thus effectively possesses the property, which as far as I know is novel, of being capable of neutralizing a substantial quantity of an acid and of a base without its foaming power and its pH being affected. A possible explanation of this property is illustrated by the following equations, in which R represents an aliphatic group having at least 18 carbon atoms, the molecule of alkali metal soap which, it is believed, forms a part of the complex molecule of mixed soap, being omitted for the purpose of simplification. V

In the presence of a mineral or an organic acid, such as hydrochloric acid or sebacic acid, the ether functions of the mixed soap, which are in reversible equilibrium, are believed to be decomposed more readily than the salt function. The triethanolamine is thus liberated from its ether functions and forms a salt With the acid while the tn'ethanolammonium salt remains unchanged.

no orncm no amour-N H CH2CH1OCHzCH: m-coorM-Gmomon CHzCHzO onion,

no among-N- 1 1 cmcmon nocmcn, n n-o o ONCH2CH:OH 2110 ornom-N-m c'HioHioH noorrgoni triethanolammonium salt triethanolammonium of fatty acid, hydrochloride basic media[ are unable to neutralize.

posed and the fatty acid is liberated, whensthe lathering power is thus destroyed:

11 cnionion R-COONfCHfiHaOH-l-HCl orricmon V, H CH2CH1OH C1-NCH2CH2OH n-ooon oniomorr In the presence of an alkali such as a sodium hydroxide solution, the alkali metal ions are believed to'combine Withone ormore free hydroxyl groups of the mixed soap to produce sodium derivatives whichmay be related to alcoholates. The reaction is incomplete and reversible and of the type occurring when ethyl alcohol is reacted with sodium hydroxide, or glucose with sodium carbonate:

nocmcm noomom-n H CHZCHXOCHZCHQ CHzCHzO CHzCHr HO CHzCHz-N HO CH2CH2 HQCHzCHz HOCHaGHz-N The presence of a the decomposition of of a sodium salt of the is liberated and the pH value rises up to about 11.5. Neutralisation of conventionalalkalimetal soaps by my improved soap takes placein the same'manne'r-as alkali metal ions are present in aqueous solution of said soaps.

As has been stated, all above equations and formulae are purely illustrative and are meant only torprovide a possible explanation ofthe peculiar chemical. composition and reactions of my improved soap, They do not claim to fully account for reactions which, in fact, may be more complicated and'in the course of which side re actions, such as polymerisations, may occur.

Instead of employing a free soap'forming fatty, acid having no lessthan 17 carbonatoms a triethanolammonium salt of such a fatty acid may be used as one of the starting materials in the process according to this invention, provided the ratio of excess triethanolamine to fatty acid isreduced accordingly to'between one and v twomolecular proportionsof triethanolamine per molecular proportion of fatty acid in said salt.

Soap embodying my invention may also be made by completely saponifying miscellaneous vegetable and/or animal fatsor oils which preferably include about 30% of castor oil and .are previously mixed with a suitable quantity of triethanolamine, with an excess caustic alkali at a temperature within the range of l00120 C., then neutralizing the uncombined caustic alkali and part of the triethanolamine with an appropriate quantity of a soap-forming fatty acid having no lessthan 17 carbon atoms, and finally heating the mixture at a temperature within the range of 120 C. until it exhibits a-homogeneous transparency which is maintained on cooling and a pH value of approximately 7.5 in 10% aqueous solution. The quantities of fatty acid and triethanolamine employed should be so chosen that/there will be between two and three molecular proportions of triethanolamine per molecular proportion of fatty acidnot required. to neutralize the uncombined caustic alkali.

fatty acid, while triethanolamine 1 It has been found that if a proportion of said soapforming fatty acid is added to the fats and oils in the starting mixture prior to saponification the hardness of the final product is increased and its action on the skin is further improved.

It is preferred that the mixture of fats or oils used should contain approximately 30% of castor oil as a more attractive transparency is imparted to the final product thereby. I have found that ricinoleates, which are obtained from castor oil by the saponification process, tend to dissolve higher fatty acid salts, such as stearates, and thus inhibit crystallisation of the latter inside the final soap on cooling.

Any suitable alkali metal soap may be used for the purpose of the present invention, those based on sodium stearate being preferred. The vegetable and/or animal fats or oils used may be olive oil, castor oil, pea-nut oil, palm gernel oil, cocoa-nut oil, beef tallow and the like. Suitable soap-forming fatty acids having no less than 17 carbon atoms are, for example, stearic acid and behenic acid.

In addition to the above ingredients it is understood that the incorporation into my improved mixed soap of other components commonly used with soap composition, such as glycerine, perfumes, coloring matters and foaming agents for example alkylsulfonates, alkylarylsulfonates, sulfonated fatty alcohols and the like, provided that such additional components do not conflict with obtaining the criteria set out above, is within the scope of this invention.

In order that the invention may be Well understood, the following examples, in which the parts are by weight, will serve to illustrate the method of procedure, it being understood that the invention is not limited thereto:

Example 1 10 kg. of a transparent alkali metal soap are mixed with 6.7 kg. of stearic acid, 8.3 kg. of triethanolamine and 3 kg. of the sodium salt of laurylsulfuric acid. The mixture is heated at 110 C. until it exhibits a homogeneous transparency which is maintained on cooling and a pH of approximately 7.5 in 10% aqueous solution. After 0.2 kg. of perfume have been added, the mixture is run into frames, cooled, cut and pressed into cakes or bars. The resulting product is suitable for use as toilet soap. It is particularly well adapted for shaving purposes owing to its heavy ratio of stearates.

Example 2 10 kg. of a transparent alkali metal soap are mixed with 10 kg. of triethanolamine stearate, 5 kg. of triethanolamine and 3 kg. of sodium alkylsulfonate, and the mixture is worked as in Example 1. The resulting product is suitable for toilet and shaving purposes.

Example 3 3.5 kg. of beef tallow, 2.5 kg. of cocoa-nut oil and 2 kg. of castor oil are mixed with kg. of triethanolamine and 2.5 kg. of 50% sodium hydroxide. The mixture is heated at 100-110 C. until saponification is completed. Then 7 kg. of stearic acid are added and the mixture is heated at 110 C. until it exhibits a homogeneous transparency which is maintained on cooling and a pH of approximately 7.5 in 10% aqueous solution. After 0.2 kg. of perfume have been added, the mixture is run into frames, cooled, cut and pressed into cakes. product is suitable for use as toilet soap.

Instead of using a single fatty acid having no less than 18 carbon atoms, it is evident that several fatty acids of this type in admixture, or natural substances containing such fatty acids and/or triethanolamine, may be employed.

What I claim is:

1. A transparent toilet soap composition in solid form, consisting essentially of (1) a transparent sodium soap prepared by saponification of a mixture of tallow, cocoanut oil and castor oil, (2) a triethanolammonium salt of stearic acid, and (3) a quantity of triethanolamine in excess over the theoretical and amounting to no less than one mol and no more than two mols per mol of soap-forming fatty acid, said transparent sodium soap (1) constituting about 35 to about 40% by weight of the composition and said triethanolammoniurn salt (2) constituting about 35 to about 40% by weight of the composition, said soap composition having a pH value of approximately 7.5 in 10% aqueous solution and having the ability to neutralize a substantial amount of an acid and of a base without its lathering potency and its pH being affected.

2. A process for the preparation of a soap composition as claimed in claim 1, which consists essentially of (l) mixing one mol of stearic acid with no less than two and no more than three mols of triethanolamine, and with a transparent sodium soap prepared by saponification of a mixture of tallow, cocoanut oil and castor oil, and then (2) heating the mixture at a temperature within the range of l00120 C. for a period not exceeding two to four hours, the duration of which period varies inversely The resulting with the temperature, until the mixture exhibits a ho-- mogeneous transparency whch is maintained on cooling, and a pH value of approximately 7.5 in 10% aqueous solution.

3. A process for the preparation of a soap composition as claimed in claim 1, which consists essentially of (1) saponifying completely with a quantity of caustic soda in excess over the theoretical, and at a temperature within the range of -120 C., a mixture of tallow,

References Cited in the file of this patent UNITED STATES PATENTS 1,828,736 Harvey Oct. 27, 1931 1,833,899 Hoyt Dec. 1, 1931 1,935,217 Ulrich et al Nov. 14, 1933 2,404,298 Kroll et a1. July 16, 1946 OTHER REFERENCES Emulsions, Booklet of Carbide and Carbon Chem. Corp, N. Y., 4th ed. (1934), pages 6 and 7.

Claims (1)

1. A TRANSPARENT TOILET SOAP COMPOSITION IN SOLID FORM, CONSISTING ESSENTIALLY OF (1) A TRANSPARENT SODIUM SOAP PREPARED BY SAPONIFICATION OF A MIXTURE OF TALLOW, COCOANUT OIL AND CASTOR OIL, (2) A TRIETHANOLAMMONIUM SALT OF STERIC ACID, AND (3) A QUANTITY OF TRIETHANOLAMINE IN EXCESS OVER THE THEORETICAL AND AMOUNTING TO NO LESS THAN ONE MOL AND NO MORE THAN TWO MOLS PER MOL OF SOAP-FORMING FATTY ACID, SAID TRANSPARENT SODIUM SOAP (1) CONSISTING ABOUT 35 TO ABOUT 40% BY WEIGHT OF THE COMPOSITION, SAID SOAP SAID TRIETHANOLAMMONIUM SALT (2) CONSTITUTING ABOUT 35 TO ABOUT 40% BY WEIGHT OF THE COMPOSITION, SAID SOAP COMPOSITION HAVING A PH VALUE OF APPROXIMATELY 7.5 IN 10% AQUEOUS SOLUTION AND HAVING THE ABILITY TO NEUTRALIZE A SUBSTANTIAL AMOUNT OF AN ACID AND A BASE WITHOUT ITS LATHERING POTENCY AND ITS PH BEING AFFECTED.
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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3793214A (en) * 1971-10-22 1974-02-19 Avon Prod Inc Transparent soap composition
US4290904A (en) * 1980-12-01 1981-09-22 Neutrogena Corporation Transparent soap
US4468338A (en) * 1983-06-13 1984-08-28 Purex Corporation Transparent soap composition
WO1988006617A1 (en) 1987-02-26 1988-09-07 Finetex, Inc. Transparent combination soap-synthetic detergent bar
US4969925A (en) * 1989-04-19 1990-11-13 Chesebrough-Pond's Usa Co., Division Of Conopco, Inc. Soap bars with polymeric additives
US5041234A (en) * 1988-03-31 1991-08-20 Lever Brothers Company, Division Of Conopco, Inc. Transparent soap bars which may contain short chain monohydric alcohols, and a method of making the same
US5217639A (en) * 1991-12-05 1993-06-08 Elizabeth Arden Company, Division Of Conopco, Inc. Dual phase toilet bar containing a clear portion and an opaque portion joined along a single curvelinear shaped surface
US5310495A (en) * 1986-11-04 1994-05-10 Lever Brothers Company, Division Of Conopco, Inc. Transparent soap bar
US5417876A (en) * 1993-10-25 1995-05-23 Avon Products Inc. Transparent soap formulations and methods of making same
US5529714A (en) * 1993-10-25 1996-06-25 Avon Products Inc. Transparent soap formulations and methods of making same
US5728663A (en) * 1996-07-02 1998-03-17 Johnson & Johnson Consumer Products, Inc. Clear, colorless soap bar with superior mildness, lathering and discolorization resistence
US5750481A (en) * 1996-01-17 1998-05-12 Calgene, Inc. Soaps produced from high laurate canola oil-based fatty acids
US5993371A (en) * 1996-01-22 1999-11-30 Henkel Corporation Transparent soap bars containing alkyl polyglycosides
US6297205B1 (en) 1999-08-30 2001-10-02 Amway Corporation Monohydric alcohol-free transparent moisturizing bar soap
US6730643B2 (en) 2001-07-23 2004-05-04 Unilever Home & Personal Care Usa Division Of Conopco, Inc. Detergent bar and a process for manufacture
US20050000046A1 (en) * 2003-07-03 2005-01-06 Michael Popovsky Cleansing pad
US20060122081A1 (en) * 2003-06-04 2006-06-08 Hindustan Lever Limited Cleaning composition
US20080045438A1 (en) * 2006-08-21 2008-02-21 D/B/A Unilever, A Corporation Of New York Softening laundry detergent
US20080223413A1 (en) * 2007-03-14 2008-09-18 Radford Philip T Color changing soap

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* Cited by examiner, † Cited by third party
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US4758370A (en) * 1987-04-30 1988-07-19 Neutrogena Corp. Compositions and processes for the continuous production of transparent soap

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US1935217A (en) * 1926-11-09 1933-11-14 Gen Aniline Works Inc Washing and cleansing textile fibers
US1828736A (en) * 1930-02-03 1931-10-27 Carbide & Carbon Chem Corp Degumming silk
US1833899A (en) * 1930-02-07 1931-12-01 Larkin Company Inc Soap
US2404298A (en) * 1945-08-10 1946-07-16 Alrose Chemical Company Saponaceous detergent having improved hard-water characteristics

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3793214A (en) * 1971-10-22 1974-02-19 Avon Prod Inc Transparent soap composition
US4290904A (en) * 1980-12-01 1981-09-22 Neutrogena Corporation Transparent soap
EP0053222A1 (en) * 1980-12-01 1982-06-09 Neutrogena Corporation Transparent soap
US4468338A (en) * 1983-06-13 1984-08-28 Purex Corporation Transparent soap composition
US5310495A (en) * 1986-11-04 1994-05-10 Lever Brothers Company, Division Of Conopco, Inc. Transparent soap bar
WO1988006617A1 (en) 1987-02-26 1988-09-07 Finetex, Inc. Transparent combination soap-synthetic detergent bar
US4851147A (en) * 1987-02-26 1989-07-25 Finetex, Inc. Transparent combination soap-synthetic detergent bar
US5041234A (en) * 1988-03-31 1991-08-20 Lever Brothers Company, Division Of Conopco, Inc. Transparent soap bars which may contain short chain monohydric alcohols, and a method of making the same
US4969925A (en) * 1989-04-19 1990-11-13 Chesebrough-Pond's Usa Co., Division Of Conopco, Inc. Soap bars with polymeric additives
US5217639A (en) * 1991-12-05 1993-06-08 Elizabeth Arden Company, Division Of Conopco, Inc. Dual phase toilet bar containing a clear portion and an opaque portion joined along a single curvelinear shaped surface
US5417876A (en) * 1993-10-25 1995-05-23 Avon Products Inc. Transparent soap formulations and methods of making same
US5529714A (en) * 1993-10-25 1996-06-25 Avon Products Inc. Transparent soap formulations and methods of making same
US5750481A (en) * 1996-01-17 1998-05-12 Calgene, Inc. Soaps produced from high laurate canola oil-based fatty acids
US5993371A (en) * 1996-01-22 1999-11-30 Henkel Corporation Transparent soap bars containing alkyl polyglycosides
US5728663A (en) * 1996-07-02 1998-03-17 Johnson & Johnson Consumer Products, Inc. Clear, colorless soap bar with superior mildness, lathering and discolorization resistence
US5962382A (en) * 1996-07-02 1999-10-05 Johnson & Johnson Consumer Products, Inc. Clear, colorless soap bar with superior mildness, lathering and discoloration resistance
US6297205B1 (en) 1999-08-30 2001-10-02 Amway Corporation Monohydric alcohol-free transparent moisturizing bar soap
US6462002B2 (en) 1999-08-30 2002-10-08 Access Business Group International Llc Monohydric alcohol-free transparent moisturizing bar soap with plastic packaging mold
US6730643B2 (en) 2001-07-23 2004-05-04 Unilever Home & Personal Care Usa Division Of Conopco, Inc. Detergent bar and a process for manufacture
US20060122081A1 (en) * 2003-06-04 2006-06-08 Hindustan Lever Limited Cleaning composition
US20050000046A1 (en) * 2003-07-03 2005-01-06 Michael Popovsky Cleansing pad
WO2005007789A2 (en) 2003-07-03 2005-01-27 Spongetech, Inc. Improved cleansing pad
US20060282966A1 (en) * 2003-07-03 2006-12-21 Michael Popovsky Cleansing pad
US7987547B2 (en) 2003-07-03 2011-08-02 Spongeables Llc Cleansing pad
US20080045438A1 (en) * 2006-08-21 2008-02-21 D/B/A Unilever, A Corporation Of New York Softening laundry detergent
US20080223413A1 (en) * 2007-03-14 2008-09-18 Radford Philip T Color changing soap

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GB729568A (en) 1955-05-11 application
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