US3001949A - Shampoo composition - Google Patents

Description

United States Patent 3,001,949 SHAMPOO COMPOSITION Kenneth Richard Hansen, Staten Island, N .Y., assignor to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Jan. 24', 1957, Ser. No. 635,932 5 Claims. (Cl. 252-153) This invention relates to new improved shampoo compositions. More particularly it relates to those shampoos consisting essentially of a water soluble higher fatty acid monoglyceride monosulfate detergent and a minor proportion of water soluble polyacrylamide.

Many types of shampoos are on the market at present. Although those based on soaps are still of great commercial importance synthetic detergent preparations account for a substantial proportion of all shampoos sold. Of such detergent preparations the organic sulfates and sulfonates are most popular. These synthetic detergent compositions are favored by many consumers because they clean more thoroughly and do not leave dulling lime soaps on the hair when used in hard water.

Although, under the conditions of use, the synthetic detergents are better cleaners, they are often disadvantageous in other respects when compared to soaps and these shortcomings should be corrected to make them entirely suitable in shampoos. Because of their superior detersive effect the synthetics often remove the natural oils from the hair, leaving it dry and difiicult to manage. In addition, the viscosities of synthetic detergent solutions are often lower than desirable. Low viscosity, coupled with the characteristically low surface tension, results in a product that is often difiicult to use because of a tendency to flow too readily and spill or run through the fingers and off the hair of the consumer.

To correct the defects noted above shampoos may be formulated to contain conditioning agents to improve manageability of the hair, viscosity modifiers and the like. Sometimes these additives are not compatible with the particular shampoo and might react with the other ingredients to develop precipitates or cause the clouding of clear shampoos. Because the various synthetic detergents are different chemically from each other, specific formulations often involve unique problems. Consequently improvements in formulas are not necessarily considered by those skilled in the art to be generally applicable but rather, to a large extent, are specific to the particular formulation and detergent composition employed.

In accordance with the present invention there is provided a liquid shampoo composition consisting essentially of water soluble higher fatty acid monoglyceride monosulfate and 0.210.0% Water soluble polyacrylamide in an aqueous medium.

Such compositions are of desirable viscosity and flow characteristics. They are pourable but still are thick enough so that they do not flow too readily between the fingers of a cupped hand or drip from the hair when applied in normal quantities in the usual manner. They possess excellent foaming power, are mild but cleanse the hair thoroughly and seem to leave some types of hair more manageable after shampooing.

In the novel compositions of this invention the essential detersive ingredient is a water soluble higher fatty acid monoglyceride sulfate detergent. Such compounds are well known in the art as excellent foamers and cleansers while still being mild to the hair and scalp. They may be prepared in any suitable manner. According to one method, glycerine and oleum are reacted and the product is admixed with a fatty oil. The resulting product, the

'tnonosulfuric acid ester of higher fatty acid mono glyceride, may be neutralized with any suitable base to form the desired water soluble detergent salt.

As sources of the higher fatty acyl group one may use the normal soap-making fats or mixtures thereof. Generally those fats will be employed whose constituent acyl groups are almost entirely within the 8 to 18 carbon atom range. Of the sulfated monoglyceride detergents those containing fatty acyl groups of about 12 to 14 carbon atoms are most suitable, especially for clear shampoos, and can be obtained by use of coconut oil, a term which includes that oil which has been hydrogenated to minimize unsaturation.

The various water soluble salts of the monosulfuric acid ester of higher fatty acid monoglycer-ide may be used in the invented compositions. Among the salt forming radicals and ions the most desirable are the ammonium, alkali metal, e.g., sodium, potassium, and lower alkylolamine containing up to about 9 carbon atoms, e.g., mono-, di and tri-ethanolamine. The ammonium detergent salt is the preferred detersive active ingredient when clear or transparent shampoos are desired, while the sodium salt is preferred for making opaque liquid shampoos, such as lotion or cream shampoos.

Due to the methods of manufacture of the sulfated monoglycerides there will usually be a large amount of water soluble inorganic salt present in these detergents after neutralization. Generally, this amount is capable of being reduced considerably by a single separation step, e.g., alcohol extraction. By repeated separations there can be produced a pure detergent free of inorganic salts but in practice such detergents are not used, largely because of the expense of the additional purification. Satisfactory shampoos based on the higher fatty acid monoglyceride sulfates and made according to the present invention may contain 0.53.5% water soluble inorganic salts, preferably about 05-25% thereof. The water soluble inorganic salts, usually principally sulfates of the detergent cation, should not constitute more than 3.5% of the shampoo or 50% of the detergent active ingredient, whichever is the lesser. To make such shampoos the synthetic detergent should usually contain less than 15%, preferably less than 10%, of water soluble inorganic salt on a detergent solids basis. More than the allowable limit of salt in a shampoo of the present type tends to decrease the stability of shampoo, as evidenced by higher cloud points of clear liquid shampoos and earlier phase separation of emulsion shampoos. Even less salt than the allowable maximum tends to render unstable similar shampoos containing other well-known thickeners.

The term detergent solids, used above, includes detergent active ingredient, water soluble inorganic salt and ether solubles (unreacted oil, free fatty acid, and other materials soluble in diethyl ether). The ether solubles content should be less than about 10% of the detergent solids. If the ether solubles are appreciably higher than 10% the cloud point of a clear shampoo of limited content of alcohol (or other suitable organic solvent for the ether solubles) will be raised, indicating instability. Emulsion or lotion shampoos will also tend to separate earlier. Both types of shampoos will darken on aging. On the other hand, the ether solubles sometimes perform a useful function. A limited amount in a formula (over 2% of the detergent solids) aids in improving hair manageability and decreasing dryness of the shampooed hair.

The essential polyacrylamide component of the invented shampoos must be of the water soluble type to be useful in these products. Such materials are mixtures of compounds of the formula,

I I C-NHz where n (the average number of acrylamide units per molecule) may vary widely. Preferably n will be such that the weight average molecular weight of the polyacrylamide will be within the range of 10,000 to 300,000 but those products outside this range whose weights are as low as 1,000 or as high as 3,000,000 may also find use, although usually they will constitute only a minor part of a mixture of polyacrylamides.

Polyacrylamide is an odorless, white solid, the most useful forms of which are soluble in water up to -20% by weight at room temperature, the rate of solution being limited by the solution viscosity. Polyacrylamide is relatively insoluble in the common organic solvents.

Polyacrylamides of various viscosity-modifying powers are made by altering the chain length of the compound, which is easily done by changing amount of catalyst, solvent, reaction time or severity of the conditions used in the polymerization step. Thus, an increase in the amount of catalyst, e.g., potassium persulfate in isopropanol, added to an aqueous reaction solution of acrylamide, will result in shorter chain lengths and lower average molecular weights, while longer reaction times, higher temperatures and less catalyst will lengthen the polymer chain.

When polyacrylamide and higher fatty acid monoglyceride monosulfate detergents are used in combination, changing of the proportions of these materials or the quantity or type of polyacrylamide will allow accurate control of the viscosity of the finished product. The higher the polyacrylamide molecular weight the more viscous the shampoo. Very close viscosity regulation may also be had by blending different polyacrylamides. Thus, a thick but flowable product of syrupy consistency can be made, or, as is more often desirable, a thinner, more free-flowing but still non-spilling shampoo can be obtained.

Clear shampoos thickened with polyacrylamide are stable for prolonged periods of time, shelf lives of over one year at room temperature (80 F.) being typical. Such a high degree of stability is unexpected since almost all gums and gum-like materials are incompatible with the detergent or else do not appreciably and reproducibly alter the viscosity or consistency of aqueous solutions thereof.

Although satisfactory clear and cream shampoos can be made from the monoglyceride sulfate detergent and polyacrylamide with water as the sole solvent, better clear products result when a lower alcohol such as ethanol, isopropanol or propylene glycol is employed as a co-solvent. The lower alcohols serve to solubilize perfumes, dyes and other hydrophobic materials which are more soluble in alcohol. They lower the cloud point .of monoglyceride sulfate shampoos. In addition they exert a solvent action on dirt on the hair and thereby supplement the emulsifying action of the detergent. The detergent, being surface-active, also increases the wetting power of the alcohol and thereby promotes better contact and more rapid solution of the soil. The lower alcohol may be added to the present shampoos during formulation. However, to effect manufacturing economies it is very desirable to utilize an alcohol-water mixture to cause phase separation of most of the inorganic salt from the neutralized organic detergent in the manner known to the art. Some alcohol remains in the detergent solution after alcohol recovery and constitutes all or a part of the alcohol content of the finished shampoo.

Although the alcohols perform useful functions in thickened monoglyceride sulfate shampoos in most instances they also tend to reduce the stability of these shampoos when viscosity modifiers other than polyacrylamide are used, apparently by decreasing the solubility of many of the viscosity modifying agents. In addition, the lower alcohol solvents also sometimes exert a thinning effect opposed to the thickening action of the modifying agent. In the case of monoglyceride sulfate shampoos containing polyacrylamide, however, controlled viscosity and stable shampoos are obtainable even in the presence of alcohols.

To secure a satisfactory shampoo the monoglyceride monosulfate detergent and polyacrylamide should both be employed within certain ranges of concentrations and proportions. When less than 5% detergent is employed there is usually no special problem in modifying the shampoo viscosity by use of the ordinary thickeners but above that concentration use of most of those products results in a shampoo of poor stability, especially in the presence of lower alcohol and water soluble salts. Shampoos containing less than 5% detergent are found to be deficient in cleansing power and are commercially unacceptable compared to shampoos of greater detergent content. Detergent solutions having over 35% higher fatty acid monoglyceride monosulfate detergent will often gel, becoming non-pourable and unsalable. Even when the detergent used does not gel at such high concentrations it tends to become cloudy and often a flocculent material separates out, which adversely affects the appearance of the shampoo. In general, therefore, it has been found that the invented shampoos should contain about 5 to 35% detergent. Usually they will contain 10 to 35% and preferably 10 to 25% of detergent for maximum effectiveness.

The proportion of polyacrylamide used is between 0.2 and 10%, preferably between 0.2 and 5% by weight. Below 0.2% no significant increase in viscosity occurs. Above 10% the shampoos tend to become too thick, gummy and gelatinous, losing the essential character of the product as a smooth, homogeneous, pourable liquid.

The amount of polyacrylamide in the present compositions should be chosen relative to the concentration of detergent and the molecular weight or chain length of the polymer. Thus, if a high molecular weight polyacrylamide is used, less will be required to produce a shampoo of given viscosity than will be needed of a corresponding compound of lower molecular weight. In selecting the particular polyacrylamide or mixture of polyacrylamides it should be kept in mind that a large proportion, even within the allowable range, of high molecular weight polymer (such as one of molecular weight of 300,000) would be difficult to dissolve efliciently and might make a jelled, rather than liquid shampoo. Correspondingly the use of a minimal proportion (0.2%) of polyacrylamidc of very low molecular weight (about 1,000) will have only a negligible influence on shampoo viscosity.

In those clear shampoo formulations in which alcohol is employed the amount used should be less than about 20%. Above that amount the shampoo will lose aesthetic qualities, will be of prohibitive cost and the alcohol will exert too great a drying effect on the hair, introduce its own odor, thin the shampoo and tend to insolubilize the viscosity modifying agent. There is no lower limit on alcohol content but to secure a cleansing and solvent effect at least 5% should usually be present in the liquid shampoos.

It is preferred to use deionized water in the present shampoos but distilled water or natural waters may also be used although with the latter a sequestering agent should usually be employed to tie up hardness and prevent clouding of the shampoo by insolubles derived therefrom. For satisfactory results the present shampoos should contain over 50% and preferably more than 66% water.

The pH of these shampoos should be kept between 5 and 7.5 to avoid both alkaline hydrolysis of the detergent and excessive acidity. Preferably, the pH should be slightly acidic, approximately 6.0. Urea, in small quantities, enough to hold the pH between 5 and 7.5, preferably around 6.0, is a suitable buffering agent.

Various compatible adjuvants may be present in the present shampoo compositions. Thus, perfume and coloring material, wetting agents, hair conditioners or superfatting agentsisuch as lanolin, fatty alcohols, fatty acids,

fatty amides, etc, may be used in minor proportions but their total should preferably not exceed about Minor amounts of water soluble phosphates such as disodium phosphate, sodium tripolyphosphate or other compounds such as the water soluble salts of ethylene diamine tetra-acetic acid may be added for their sequestering activity. Preservatives may be used to inhibit mold and fungus as well as bacterial growth during storage. Bactericides may be added for germicidal treatment of hair and scalp.

The invented shampoo compositions may be made in any suitable liquid state pourable at room temperature. Usually the thinner of these liquids will have a viscosity of about 20 centipoises at 80 F. The flow time, which is by definition the time in seconds that it takes a volume of shampoo to flow by gravity out of a certain cylindrical container under a certain liquid head through a standard tube is a more accurate measure than viscosity of the flow characteristics of a shampoo of importance to the consumer because it measures all flow resisting forces, not just the resistance of the liquid to shear.

The flow time is determined in the following manner.

A graduated glass 100 milliliter cylinder with the bottom removed, of 24 centimeters length and 2.5 cm. internal diameter is held vertically. Both ends of the cylinder are open. A No. 2 rubber stopper is used to close ofi the lower opening; the stopper is bored axially and in the hole is inserted a metal tube of 14 cm. length and 4 millimeters inside diameter, leading from a point near the bottom of the cylinder to the atmosphere. The cylinder is filled to the 100 ml. mark with shampoo, the metal tube also being filled, and being closed off at its outlet. The outlet is opened and the time is recorded when 10 ml. shampoo has flowed out of the cylinder. The time is again recorded when 60 ml. have been drained. The difference is the flow time. The liquid at the 10 ml. height is 15.8 cm. above the tube top and at the 60 ml. height is only 6.3 cm. above that point.

Water at 80 F. has a flow time of 3 seconds while the present shampoos will flow in about 8 to 200 seconds, preferably from to 100 seconds at the same temperature.

Either clear liquid shampoos or liquid cream shampoos may be made. In either case the polyacrylamide is preferably first dissolved in some hot water after which it may be added to the balance of the composition or, before compounding, to the solution of detergent base (which may contain both water and alcohol). Clear shampoos made from ingredients containing no cloudforming impurities, are sparkling. If filtration is considered desirable to remove insoluble impurities which sometimes might be in the various ingredients the shampoo will be found filterable and the final product will be transparent.

The following specific examples are further illustrative of the invention but it is not limited thereby. All amounts or percentages throughout this specification and in the claims are by weight unless otherwise indicated.

Example I 10.9 parts of acrylamide were dissolved in 87.4 parts of deionized water. The solution was warmed to 68 C. under a stream of nitrogen, at which point a solution of 0.021 part of potassium persulfate catalyst in 1.68 parts isopropanol was added, the temperature rising to 8090 C. The reaction mixture was held at this temperature for 2 hours, after which analysis disclosed it to contain 10.7 parts polymer of an average molecular weight of about 15,500, the yield being over 98%. The polymer was diluted with water and spray-dried.

From this dried polyacrylamide were made shampoos of the following formulas:

1 Ammonium salt of coconut oil fatty acids monoglyceride monosulfate detergent. It contains about 10% ammonium sulfate and about 10% ether soluble material due to the method of manufacture.

2 As detergent concentrate=56.1%.

The shampoos are made by dissolving the required amount of polyacrylamide in boiling deionized water, cooling to room temperature or slightly above and then admixing wit-h detergent concentrate in which the perfume has previously been dissolved. The pI-Is of the resulting products were adjusted to 6.1 and 6.2 respectively by addition of sulfuric acid.

Clear stable shampoos resulted. Flow times at F. were 8 and 21 seconds respectively.

Example II A 10% aqueous solution of polyacrylamide of a weight average molecular weight of about 200,000 was used to make the following shampoos, the compounding being done at room temperature.

O D E Detergent I 21.0 2 21.0 2 21.0 Ethanol 3 9.8 2 9. 8 2 9.8 Water I 24. 0 2 24.0 2 24. 0 10% Aqueous (M.V V.=200,000) 40. 0 20. 0 15. O Delonized Water 4.8 24.8 29.8 Perfume 0. 4 O. 4 0. 4

1 Ammonium salt of coconut oil fatty acids monoglyceride monosulfate detergent. It contains about 10% ammonium sulfate and about 10% ether soluble material due to the method of manufacture.

2 As detergent concentrate=54.8%.

To make Formula C the detergent concentrate, perfume, and deionized water were mixed and the resulting solution was added to the polyacrylamide solution at room temperature. Formulas D and E are dilutions of C with a low viscosity shampoo containing no polyacrylamide.

Shampoos made were stable and clear. D and E gave fiow times of 42 and 20 seconds respectively at 80 F.

Example 111 A dry powdered polyacrylamide of weight average molecular weight approximating 200,000 was employed to regulate the viscosities of the following shampoos.

Detergent 1 2 21.0 3 21. 0 Ethanol 2 9. 3 2 9. 3 Water i! 25. 1 2 25. 1 Polyacrylamide (M.W.=200,000) 2.0 0.5 Laurie Myristic Diethanolamide (a mixture) 5. 0 5.0 Deionized Water 37. 2 88. 7 Perfume O. 4 0. 4

l Ammonium salt of coconut oil fatty acids monoglyceride monosulfate detergent. It contains about 10% ammonium sulfate and about 10% ether soluble material due to the method of manufacture.

2 As detergent concentrate=55.4%.

The detergent concentrate, lauric myristic diethanolamide and perfume were mixed at room temperature. The dried high molecular weight (200,000) polyacrylamide was dissolved in very hot water and was admixed with the rest of the shampoo components. The resulting products were adjusted in pH to 6.l-6.2 by addition of acid. Flow times at 80 F. were 71 and 23 seconds, the latter being a reading corrected to 80 F. by interpolation. The shampoos were filtered to remove some insoluble impurities. The finished shampoos were sparkling clear in appearance.

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 made and substituted therefor without departing from the principles and true spirit of the invention or going outside the scope of the claims.

What is claimed is:

1. A liquid shampoo consisting essentially of about 5 to 35 of a water soluble higher fatty acid monoglyceride monosulfate detergent having 8 to 18 carbon atoms in the higher fatty acid group and a minor proportion of water soluble polyacrylamide, in an aqueous medium, the proportion of water soluble polyacrylamide being sufficient to-form a stable shampoo of increased viscosity.

2. A liquid shampoo consisting essentially of about 5 to 35% of a water soluble higher fatty acid monoglyceride monosulfate detergent having 8 to 18 carbon atoms in the higher fatty acid group and about 0.2 to 10% of water soluble polyacrylarnide of molecular weight distribution within the range 1,000 to 3,000,000, in an aqueous solution.

3. A clear liquid shampoo consisting essentially of about 10 to 35% of an ammonium higher fatty acid monoglycen'de monosulfate detergent having 8 to 18 carbon atoms in the higher fatty acid group and about 0.2 to 5% of water soluble polyacrylarnide of molecular weight distribution within the range 10,000 to 300,000, in an aqueous solution.

4. A clear liquid shampoo comprising, aqueous solution, 10 to 35 of the ammonium salt of monosulfuric acid ester of higher fatty acid monoglyceride of 8 to 18 carbon atoms, 0.2 to 10% of water soluble polyacrylamide of molecular weight within the range 10,000 to 300,000, 5-20% of a lower aliphatic alcohol, the shampoo being at a pH in the range 5-7.5.

5. A clear liquid shampoo comprising, in aqueous solution, 10 to 35 of the ammonium salt of the monosulfuric acid ester of the monoglyceride of coconut oil fatty acid, 0.2-5% of water soluble polyacrylamide of molecular weight within the range 10,000 to 300,000, 520% of a lower aliphatic alcohol selected from the group consisting of ethanol and isopropanol and 05-25% of a water soluble inorganic salt, the shampoo being at a pH in the range 5-7.5.

References Cited in the file of this patent UNITED STATES PATENTS 1,976,679 Fikentscher et al. Oct. 9, 1934 2,607,740 Vitale et al Aug. 19, 1952 2,674,580 Henkin Apr. 6, 1954 2,706,180 Sylvester Apr. 12, 1955 2,773,834 Henkin Dec. 11, 1956 2,827,964 Sandiford Mar. 25, 1958 2,879,231 Allen et a1 Mar. 24, 1959 FOREIGN PATENTS 807,280 France Oct. 12, 1936 889,373 France Oct. 4, 1943 OTHER REFERENCES Surface Active Agents by Schwartz et al., pages 444 446, Interscience Publishers, Inc., NY. (1949).

Lesser: Shampoos Soap and Sanitary Chemicals, January 1951, pages 38-41, 115, 117 and 119.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,001,949 September 26, 1961 Kenneth Richard l-lalrlsen It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below. 1

Column 4, line 64, for "66%" read 60% column 8, line 1, before "aqueous" insert in Signed and sealed this 7th day of Aggilst'l962'.

(SEAL) Attestz I L. LADD ERNEST w. SWIDER v P Attesting Officer Comrmssmner of Patents

Claims (1)

1. A LIQUID SHAMPOO CONSISTING ESSENTIALLY OF ABOUT 5 TO 35% OF A WATER SOLUBLE HIGHER FATTY ACID MONOGLYCERIDE MONOSULFATE DETERGENT HAVING 8 TO 18 CARBON ATOMS IN THE HIGHER FATTY ACID GROUP AND A MINOR PROPORTION OF WATER SOLUBLE POLYACRYLAMIDE, IN AN AQUEOUS MEDIUM, THE PROPORTION OF WATER SOLUBLE POLYACRYLAMIDE BEING SUFFICIENT TO FORM A STABLE SHAMPOO OF INCREASED VISCOSITY.