US2674580A - Liquid shampoo - Google Patents

Description

Patented Apr. 6, 1954 UNITED STATES PATENT OFFICE gate-Palmolive Delaware Company,

a corporation of No Drawing. Application July 20, 1950,. Serial No. 175,013

Claims. 1

The present invention relates to opaque liquid shampoos and, more particularly, to such liquid shampoo compositions of the type of the anionic synthetic sulfated and sulfonated detergent salts.

Many varied types of shampoo compositions have been developed in the past. They generally contain as the active ingredient or principal cleansing agent either soap, i, e. water soluble salts of fatty acids, or various synthetic detergents, usually the anionic sulfates and sulfonates as a base.

Most shampoos are generally clear, relatively viscous solutions. Within recent years, however, shampoos of the creamy or milky type have been developed and possess a number of advantages. In general, they have a pleasing creamy-like appearance, are relatively good emulsifiers, lather profusely, etc.

These cream-type shampoos have generally been manufactured in the form of a paste; and by reason of their high consistency they are usually sold in collapsible tubes or jars.

It has been attempted recently to prepare shampoos having the desirable features of both the liquid and paste types of shampoo whereby there may be unitarily obtained a creamy opaquelike appearance of such consistency that the material flows from a suitable container at normal temperature.

There are still a number of problems which are of general concern however with regard to liquid cream shampoos. A primary consideration has been the general instability of these liquid types, such that at temperatures of up to about 110 F., phase separation occurs and translucen-cy results. It has been said that such types of shampoos are better known for their perversity than for their stability.

It has been common to add various thickeners or hair conditioning aids to shampoo compositions with stearic acid being preferred in many instances. While it is relatively effective for some purposes it also renders or at least does not retard the characteristic instability of liquid cream shampoos at elevated temperatures.

It has now been discovered that opaque liquid shampoos consisting essentially of a detersive salt from the group consisting of the anionic sulfated and sulfonated detersive salts, an aqueous medium, and having a minor proportion of behenic acid present therein exhibts a high degree of stability, particularly at elevated temperatures, in addition to a number of other desirable characteristics. The novel liquid compositions of the present invention are further characterized by high foaming power, excellent cleansing properties when applied to human hair in soft and hard water, and in their physical appearance by milky, pearly, or creamy consistency or body. It is an added feature of the present invention that the behenic acid may be present in a partially neutralized state whereb the resulting mixture of free behenic acid and behenic acid soap proves also to be effective in the relationship set forth. It is highly desirable that the pH of the liquid shampoo composition be within the range of about a pH of 5 to about 7.5 and preferably less than about 7, in order to insure the presence of adequate amounts of free behenic acid, prevent or minimize irritation to the skin due to excess alkalinity, maintain high foaming power, etc. More particularly, the use of a mixture of behenic acid and amine soaps thereof yield highly desirable resutls.

The novel compositions of the present invention contain as the active ingredient the anionic sulfated and sulfonated detergents (including suitable mixtures thereof). Included therein are the aliphatic sulfated 0r sulfonated agents, such as the aliphatic acyl-containing compounds wherein the acyl radical has about 8 to about 22 carbon atoms, and more particularly, the aliphatic carboxylic ester type, containing at least about 10 and preferably about 12 to about 26 carbon atoms to the molecule. Among the aliphatic detersive compounds, it is preferred to use the sulfated aliphatic compounds having about 12 to about 22 carbon atoms. As suitable examples of aliphatic detergents may be found the sulfuric acid. esters of polyhydric alcohols incompletely esterified with higher fatty acids, e. g.

- coconut oil monoglyceride monosulfate, tallow diglyceride monosulfate; the long chain pure or mixed higher alkyl sulfates, e. g. lauryl sulfate, cetyl sulfate, higher fatty alcohol sulfates derived from reduced coconut oil fatty acids; the hydroxy sulfonated higher fatty acid esters, e. g, higher fatty acid esters of 2,3 di-hydroxy propane sulfonic acid; the higher fatty acid esters of low molecular weight alkylol sulfonic acids, e. g. oleic acid amides of amino alkyl sulfonic acids, e. g. lauric amide of taurine, and the like.

Within the ambit of the invention are the alkyl aryl sulfonate detergents also though these are not preferred generally because of their great drying power. These aromatic sulfonate detergents are also known in the art. They may be mononuclear or polynuclear in structure. More particularly the aromatic nucleus may be derived from benzene, toluene, xylene, phenol, cresols,

naphthalene, etc. The alkyl substituent on the aromatic nucleus may vary widely, as long as the desired detergent power of the active ingredient is preserved. While the number of sulfonic acid groups present on the nucleus may vary it is usual to have one such group present in order to preserve as much as possible a balance between the hydrophilic and hydrophobic portions of the molecule.

More specific examples of suitable alkyl aromatic sulfonate detergents are the higher alkyl aromatic sulfonates. The higher alkyl substituent on the aromatic nucleus may be branched or straight-chain in structure; it comprises moreover such groups as decyl, dcdecyl, keryl, pentadecyl, hexadecyl, mixed long-chain alkyls derived from long-chain fatty materials, cracked paraffin wax olefins, polymers of lower monoolefins, etc. Preferred examples of this class are the higher alkyl mononuclear aryl sulfonates wherein the alkyl group is about 8 to about 22, and preferably about 12 to 18 carbon atoms.

These various anionic detergents are to be used in the form of their Water soluble salts such as the amine, alkali metal and alkaline earth metal salts. While the sodium, potassium salts and the like may be suitably employed, it is preferred to use the ammonium, lithium, amine including alkylolamine salts in view of their generally greater solubility in aqueous solution. More particularly it is preferred to use the ammonium, monoethanolamine, diethanolamine, triethanolamine salts and mixtures thereof because of the excellent results attained with their use, particularly with the higher alkyl sulfates, the higher fatty acid monoglycerides sulfates (and mixtures thereof) as the active ingredients. Their concentration in the liquid compositions of the present invention is generally at least about and usually between about -35%, though it is preferred to use from about -30% by weight of the total composition. in liquid shampoos, these synthetic detergents in general act to dry the scalp and hair excessively, and leave it unmanageable unless modified in some manner.

The behenic acid in the liquid compositions of the present invention performs a multiplicity of functions. It acts as an opacifier to keep the liquid shampoo opaque and creamy at temperatures of the order of up to about 110 F. with maintenance of proper fluidity, it assists in the stabilization of such liquid emulsions, acts as a hair conditioner to leave the hair lustrous and manageable, etc. The amount of behenic acid to be used in formulation is variable and should be integrated with the concentration of the de tergent in the liquid mixture in order to maintain the proper consistency. Where maximum amounts of detergents are used, minimum acceptable amounts of behenic acid should be employed, with this general guide varying inversely also. The amount of behenic acid will ordinarily be up to about 10% by weight of the final composition, the ingredients being so proportioned to form an opaque liquid emulsion. Generally highly satisfactory results may be obtained in amounts of behenic acid of about 1 to about 5%. Where excessive amounts of behenic acid are employed, the liquid shampoo becomes too thick to pour, in addition to other disadvantages, thus destroying the characteristic features of the present invention.

These ingredients are proportioned and mixed with an equeous base to form an opaque emulsion, generally of the oil-in-water type, wherein the detergent is partially dissolved in the aqueous phase and partially dispersed in line particles throughout said solution to yield a milky or creamy liquid. The amount of aqueous base is variable but must be sufficient to yield proper fluidity or pourability to the composition, using controlled amounts of solid ingredients. The amount of water will usually be above about 50% by weight and preferably above about 60% for optimum results.

Itis a feature of the present invention that the behenic acid may be present in a partially neutralized state with certain advantages. Thus an appropriate alkali may be added to the mixture to partially neutralize the free behenic acid and produce thereby a mixture of free behenic acid and behenic acid soap. By this means, the acidity of the composition may be controlled so that it is neither excessively acid nor alkaline in character, and the composition is further stabilized since the formed soap'is an added emulsifying agent.

As the appropriate alkali, it is preferred to use the lower amines, e. g. up to about 5 carbons, and particularly, alkylolamines such as mono-, di, and triethanolamine, mono-isopropanolamine, etc. The soaps of these amines posses the added advantages of lowering the freezing point of the composition, and possess a normal pH in aqueous solution closer to I than the corresponding sodium soaps for example. The alkali metal bases such as sodium and potassium hydroxide may be used however. Of the latter, it is preferred to use the potassium base in View of the greater solubility of its soaps.

It is within the scope of this invention that the mixture of behenic acid and its corresponding soap may be prepared by the total or partial addition of behenic acid soap to the composition, with prior, simultaneous or subsequent adjustment of the pH of the composition to insure the presence of desired amounts of free behenic acid. It is preferred however for optimum results generally to prepare the mixture in situ by the addition of free behenic acid and minor amounts of alkali for partial neutralization as indicated.

For optimum results, the pH of the liquid shampoo should be within the range of about 5 to about 7.5 and preferably less than about '7, e. g. 5.8 to '7. Compositions which are excessively acid or alkaline have adverse effects on the scalp and hair. The use of pH values of the order indicated, moreover, insures the presence of adequate amounts of free behenic acid to accomplish the purposes set forth. The use of highly alkaline values substantially above the order indicated tends to convert the behenic acid more substantially to the form of soap. Extremely large amounts of soap in combination with the synthetic detergents in these compositions are undesirable since they appear to adversely modify the foaming power, tend to leave a soapy film on the hair etc.

It is considered for optimum results that the pH should be less than about 7. Such a shampoo composition in use would tend to neutralize alkaline residues on the hair and scalp and serve to tone up the stratum by restoring to it a beneficial mild acidity. Moreover, the formation of soap particularly the insoluble types of soap produced in hard water is inhibited by the maintenance of pH values generally unsuitable for their production. Such pH ranges appear to be eminently suitable for the stabilization of the active ingredients per se, particularly for the I aliphatic carboxylic ester type of detergent salts such as the higher fatty acid monoglyceride monosulfates which are more liable to decomposition on the alkaline side.

It is common to add various adjuvant materials to shampoo compositions. Thus, the shampoo ordinarily will contain a perfume which should be selected so as to be compatible with the character of the shampoos. It is preferred also to include a small amount of a buffer material to aid in the adjustment and maintenance of the desired pH of the finished product. Suitable buffering materials include borax, the various inorganic water soluble phosphates such as disodium phosphate, trisodium phosphate, sodium tripolyphosphate, sodium hexametaphosphate, the corresponding potassium or ammonium compounds thereof, etc. Other ingredients which may be used in shampoos for imparting desired qualities -to the hair after washing may be incorporated in the present compositions. Thus, hair conditioners or superfatting materials such as lanolin, fatty alcohols, fatty amides, fatty acids, etc. may generally be used in minor proportions, e. g. up to about 5%. The higher fatty alcohols such as myristyl, cetyl-and stearyl alcohols have the advantage of maintaining the foaming properties of the composition at a desirable high level usual 1y. Among suitable amides are the higher fatty acid amides such as myristamide, palmitylamide,

stearyl amide, palmitylethanolamide, myristylpropanolamide, etc. Glycerine may be added up to about generally. Coloring materials or dyes may be added to tint the liquid if desired. Similarly, whitening agents may be used if desired. Preservatives such as sodium benzoate and the like may be added to prevent mold growth. Gum mucilages such as carboxymethylcellulose, tragacanth and the like ma be used as desired similarly.

The following specific examples are further illustrative of the nature of the present invention, but it is to be understood that the invention is not limited thereto.

Example I The following composition is a white opaque liquid cream shampoo.

Per cent Detergent salt 1 25.0 Behenic acid 3.5 Lanolin 0.5 Triethanolamine 1.2 Methyl p-hydroxy benzoate 0.15 Perfume oil 0.4 Water 69.25

1 Sodium salt of sulfated monoglyceride of hydrogenated coconut oil fatty acids. It contained about 10% by weight of inorganic sulfate formed in its manufacture.

The detergent salt in the form of dry chips, the preservative and water are heated to 180 F.; and the lanolin and behenic acid are melted at a temperature of about 200 F., and added to the de tergent solution. The ingredients are mixed to form a homogeneous mixture and the triethanolamine is added reacting partially with the behenic acid in situ. The perfume is added at 115 F. and the batch is cooled with continuous stirring at 80 to 90 F. The resulting liquid cream shampoo has a pH of about 6.5.

This formulation having an acidic pH, and a mixture of free behenic acid and triethanolamine soap thereof, is subjected to oven storage at 110 F. Under such conditions, the composition main- 'tained its creaminess with no separation for over one month.

A similar formulation substituting stearic acid for the behenic acid turns translucent at F. overnight and separates within several days.

Example II The following i another satisfactory opaque liquid shampoo.

1 Sodium salt of sulfated monoglyceride of hydrogenated coconut oil fatty acids. It contained about 10% by weight of inorganic sulfate formed in its manufacture. The composition has a pH of about 6.5.

Example III A further satisfactory liquid cream shampoo may be prepared from the following formulation:

Per cent Detergent salt 1 15.0 Behenic acid 3.5 Water Balance 1 Sodium lauryl sulfate. The composition is adjusted to a pH of about 7.5 by addition of sodium hydroxide.

Example lV 7 Per cent Detergent salt 25.0 Behenic acid 3.0 Triethanolamine 1.0 Water Balance 1 Triethanolamine lauryl sulfate. The composition has a pH of about 7.

Example V Per cent Detergent salt 1 20.0 Behenic acid 2.0 Triethanolamine 0.7 Water Balance Ammonium salt of sulfated monoglyceride of hydrogenated coconut oil fatty acids. It contained about 10% inorganic salts. The composition has a pH of about 6.5.

As indicated above in Example I, the method of manufacture is relatively simple. In general, the solid ingredients are to be melted and stirred into the aqueous medium at elevated temperatures to form a homogeneous mixture, perfume added, whereupon the opaque liquid shampoo may be cooled and bottled or otherwise prepared for use. Other methods of manufacture may be employed if desired including continuous proportioning of the ingredients into a mixing apparatus where the ingredients are thoroughly blended at elevated temperatures and thereafter cooled to the desired temperature.

The term consisting essentially of as used in the definition of the ingredients present in the composition claimed is intended to exclude the presence of other materials in such amounts as to interfere substantially with the properties and characteristics possessed by the composition set forth but to permit the presence of other materials in such amounts as not substantially to affect said properties and characteristics adversely.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention.

Having described the invention, what is desired to be securedby Letters Patent is:

1. An opaque liquid shampoo having a pH from about 5 to 7.5 and consisting essentially of watersoluble detergent selected from the group consisting of the anionic organic sulfated and sulfonated detergent salts, an aqueous medium, and a minor amount of behenic acid therein sufficient to maintain said liquid shampoo opaque, creamy and stable against separation at elevated temperatures.

2. An opaque liquid shampoo in accordance with claim 1 which contains a minor amount of an ethanolamine.

3. An opaque liquid shampoo consisting essentially of water-soluble aliphatic anionic sulfated detergent salt, an aqueous medium, and i a minor amount of behenic acid therein sufficient to maintain said shampoo opaque, creamy and stable against separation at elevated temperatures, said shampoo having a pH from about 4. An opaque liquid shampoo consisting essentially of water-soluble higher fatty acid monoglyceride sulfate detergent salt, an aqueous medium, and a minor amount of behenic acid suflicient to maintain said liquid shampoo opaque, creamy and stable against separation at elevated temperatures, said shampoo having a pH from about 5 to 7.

'5. An opaque liquid shampoo consisting essentially of water-soluble higher alkyl sulfate detergent salt, an aqueous medium, and a minor amount of behenic acid sufficient to maintain said liquid shampoo opaque, creamy and stable against separation atelevated temperatures, said shampoo having a pH from about 5 to 7.5.

6. An opaque liquid shampoo consisting essentially of water-soluble hydrogenated coconut fatty acid monoglyceride sulfate detergent salt, an aqueous medium and a minor amount of behenic acid therein suificient to maintain said 1iquid shampoo opaque, creamy and stable against '8 separation at elevated temperatures, said liquid shampoo having a 'pH of about 5;8 to 7.

'7. An opaque liquid shampoo consisting essentially of about 10-35% by weight of watersoluble detergent selected from the group consisting of the anionic organic sulfated and sulfonated detergent salts and about 110% by weight of behenic acid in an aqueous medium, said shampoo having a pH of about 5 to 7.5.

3. An opaque liquid shampoo consisting essentially of about 10-35% by Weight of watersoluble higher fatty acid monoglyceride sulfate detergent salt and about 1-10% by weight of behenic acid in an aqueous medium, said shampoo having a pH from about 5 to 9. An opaque liquid shampoo in accordance with claim 8 which contains a minor amount of triethanolamine.

10. An opaque liquid shampoo consisting essentially of about 10-35% by weight of Watersoluble higher alkyl sulfate detergent salt and about 1-10% by weight of behenic acid in an aqueous medium, said shampoo having a pH from about 5 to 7.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,086,479 Schrauth July 6, 1937 2,144,884 Kritchevsky Jan. 24, 1939 2,164,717 Kritchevsky Jan. 24, 1939 2,519,062 Miskel Aug. 15, 1950 FOREIGN PATENTS Number Country Date 53, Switzerland Feb. 1 10 723,775 France Apr. 14, 1932 833,932 France Nov. 4, 1938 OTHER REFERENCES Martin: Modern Soap and Detergent Industry, vol. 1 (1931), Section 1, page 19. (Copy in Div. 64.)

Bennett: Chemical Formulary (1941), vol. V, page 63. (Copy in Div. 64.)

Claims (2)

1. AN OPAQUE LIQUID SHAMPOO HAVING A PH FROM ABOUT 5 TO 7.5 AND CONSISTING ESSENTIALLY OF WATERSOLUBLE DETERGENT SELECTED FROM THE GROUP CONSISTING OF THE ANIONIC ORGANIC SULFATED AND SULFONATED DETERGENT SALTS, AN AQUEOUS MEDIUM, AND A MINOR AMOUNT OF BEHENIC ACID THEREIN SUFFICIENT TO MAINTAIN SAID LIQUID SHAMPOO OPAQUE, CREAMY AND STABLE AGAINST SEPARATION AT ELEVATED TEMPERATURES.

2. AN OPAQUE LIQUID SHAMPOO IN ACCORDANCE WITH CLAIM 1 WHICH CONTAINS A MINOR AMOUNT OF ETHANOLAMINE.