GB2257907A - Cosmetic gel comprising a glycyrrhizic acid compound and a polymer - Google Patents

Abstract

A cosmetic gel comprising a glycyrrhizic acid compound and a gelation accelerating high polymeric compound, which may further contain a surface active agent and an oil-soluble component, is described.

Description

TITLE OF THE INVENTION Cosmetic Gel DETAILED EXPLANATION OF THE INVENTION: Field of the Invention: This invention relates to a cosmetic gel and, more particularly to an aqueous gel cosmetic that excels in long-term stability and feel on use. The invention further relates to an aqueous gel cosmetic capable of containing an oil-soluble component in a relatively large proportion.

The invention furthermore relates to an aqueous gel cosmetic comprising ingredients that require no aging in the production process.

Prior Art: It is known that an aqueous solution of a glycyrrhizic acid component (e.g., glycyrrhizic acid and its sodium.

potassium or ammonium salt as described in KESHOHIN GENRYO KIJUN and HAN-YO KESHOHIN GENRYOSHU) has the property of forming a gel (coagulation) in a pH range of from 2.5 to 5.8.

For example, Japanese Patent Publication No. Sho-45-21397 discloses a cosmetic aqueous gel obtained by adjusting a 0.1 to 10% aqueous solution of glycyrrhizin compound to a pH between 2 and 6. Japanese Patent Application Laid-Open No. Sho-58-163429 discloses an emulsified composition containing glycyrrhizic acid or a salt thereof, a water-soluble polyhydric alcohol, and an oil-phase component. It is stated that the composition is a transparent or semi-transparent viscous liquid or gel.

Problems to be Solved by the Invention: However, aqueous gels prepared from glycyrrhizic acid compounds have had the disadvantage of poor long-term preservability due to poor gel stability. Besides, they lack a non-tacky and light feel on use and have been unsatisfactory as cosmetics. An increase in the amount of the glycyrrhizic acid compound for the purpose of improving gel stability, though accomplishing the purpose, results in production of gels which when applied to the skin, have deteriorated spreadability and feel tacky, thus failing to provide products favorable as cosmetics.

On the other hand, where an oil-soluble component is incorporated in an aqueous gel containing a glycyrrhizic acid compound as a gelling agent while retaining the transparency of the gel, a permissible amount of incorporation is only about 0.1% at the highest. That is, components useful as cosmetics such as oil-soluble vitamins cannot be incorporated in an effective proportion (i.e., up to about 1%). This is because incorporation of any surface active agent into such aqueous gels in order to solubilize the oil-soluble component results in reduction in gel strength and deterioration of long-term stability.

In addition, aqueous gels containing a glycyrrhizic acid compound have a production problem in that an aging step is necessary. For example, a formulation must be cooled to about lOC and allowed to stand overnight at that temperature.

Accordingly, an object of the present invention is to provide an aqueous gel cosmetic excellent in long-term stability and feel on use.

Another object of the present invention is to provide an aqueous gel cosmetic capable of containing a relatively large amount of an oil-soluble component.

A further object of the present invention is to provide an aqueous gel cosmetic having such a formulation that obviates the need for aging.

Means for Solving the Problems: The inventors have conducted extensive investigations for obtaining an aqueous gel cosmetic free from the abovementioned disadvantages while using a glycyrrhizic acid compound as a gelling agent. As a result, it has now been found that the combination of a glycyrrhizic acid compound and a specific high polymeric compound having a gelation accelerating function affords an aqueous gel cosmetic that excels in long-term stability and feel on use. It has also been found that these components may be supplemented with a surface active agent thereby making it possible to incorporate a relatively large quantity of an oil-soluble component without adversely affecting the stability of the gelling agent.

The present invention relates to a cosmetic gel comprising a glycyrrhizic acid compound and a gelation accelerating high polymeric compound.

The present invention also relates to a cosmetic gel comprising a glycyrrhizic acid compound, a gelation accelerating high polymeric compound, a surface active agent, and an oil-soluble component.

Glycyrrhizic acid compounds which can be used in the present invention include glycyrrhizic acid and salts thereof. The glycyrrhizic acid salts preferably include inorganic salts, e.g., a potassium salt, a sodium salt, a lithium salt, and an ammonium salt; and basic amine salts, e.g., a monoethanolamine salt and a triethanolamine salt.

The glycyrrhizic acid compound is used in an amount of from 0.5 to 10% by weight, and preferably from 2 to 8% by weight, based on the total weight of the cosmetic. If its amount is less than 2% by weight, the resulting gel is poor in long-term stability. If it exceeds 10% by weight, the resulting gel is unsuitable as a cosmetic, feeling tacky and exhibiting poor spreadability on the skin.

High polymeric compounds which can be used in the present invention have a function of enhancing and accelerating gelation of the glycyrrhizic acid compound and they include gums, natural water-soluble high polymeric compounds, and synthetic high polymeric compounds. Specific examples of gums are gum arabic, gum benzoin, gum dammar, gum guaiac, Irish moss, gum karaya, gum tragacanth, galactomannan, and quince extract. Specific examples of natural water-soluble high polymeric compounds are agar, casein, dextrin, gelatin, pectin, sodium pectate, starch, sodium alginate, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

Specific examples of synthetic high polymeric compounds are polyvinyl alcohol, polyvinyl methyl ether, polyvinylpyrrolidone, polyacrylic acid, polyacrylates, carboxyvinyl polymers, and polyethyleneimine.

The high polymeric compound is used in an amount of from 0.01 to 5.0% by weight, and preferably from 0.1 to 2.0% by weight, based on the total weight of the cosmetic. If its amount is less than 0.01% by weight, the resulting gel has a reduced gel strength. If it exceeds 5.0% by weight, the gel has too a high gel strength, lacking in spreadability, and is unsuitable as a cosmetic.

Surface active agents which can be used in the present invention include nonionic, anionic, cationic and amphoteric surface active agents. The kind and amount of the surface active agent to be incorporated are subject to variation depending on the kind and amount ratio of an oil-soluble component to be incorporated. The surface active agent preferably has an HLB value ranging from 8 to 18.

Oil-soluble components which can be used in the cosmetics of the present invention include those which are commonly employed in cosmetics, such as perfumes, hormones, and oil-soluble vitamins. Other oil-soluble components may also be used according to the end use.

Examples: EXAMPLES 1 AND 2 Cosmetic preparations having the composition shown in Table 1 below were prepared. Ease of preparation, properties of the resulting preparations, long-term gel stability, and rheological characteristics were examined.

TABLE 1 Compar. Compar.

Example Example Example Example Composition 1 2 1 2 (wt%) (wt%) (wt%) (wt%) Component A: Monoammonium glycyrrhizate 4.0 4.0 4.0 Purified water 85.0 83.4 83.8 87.4 Carboxyvinyl polymer 0.3 0.3 0.3 Sodium hydroxide 0.1 0.1 0.1 Component B: Alcohol 10.0 10.0 10.0 10.0 Polyoxyethylene glyceryl pyroglutamate 0.5 1.5 1.5 1.5 (25 E.O) Vitamin E 0.05 0.1 0.1 0.1 Octyl p-dimethyl- 0.5 0.5 0.5 aminob enzoat e Perfume 0.05 0.1 0.1 0.1 Preparation: To a prescribed amount of Component A uniformly dissolved at 70'C was added dropwise a prescribed amount of uniformly dissolved Component B while maintaining at 70C with stirring.After the dropwise addition, the stirring was further continued at an ambient temperature to cool the mixture to 30it. When necessary, the mixture was cooled to 5iC and subjected to aging for gelation at that temperature.

The ease of preparation, properties of the resulting preparations, and long-term stability of the gels are shown in Table 2 below.

TABLE 2 Compar. Compar.

Example Example Example Example 1 2 1 2 6-hour 6-hour Ease of' gelled gelled aging aging Preparation without without needed for needed for aging aging gellation gellation easily easily easily Properties disintegrable disintegrable disintegrable creamy gel gel gel state Long-term gel excellent excellent poor stability The term "easily disintegrable" as used herein means the property of a gel exhibiting such high thioxotropy that a strong stress (resistance) is initially exhibited on loading, with the stress (resistance) being abruptly lost when the load exceeds a certain limit.

As can be seen from the results in Table 2, each of the compositions of Examples 1 and 2 (containing 0.7% of an oil-soluble component in Example 2) gelled without requiring an aging step to have a jelly-like easy-to-disintegrate property, a desirable property of cosmetic gels. Further, the resulting gel exhibited excellent long-term stability. On the other hand, the composition of Comparative Example 1 using the glycyrrhizic acid compound alone required aging for gelation. Besides, the resulting gel was somewhat hard like agar and was poor in longterm stability. The composition of Comparative Example 2 using the gelation accelerating high polymeric compound alone did not gel and produced only a creamy preparation, failing to provide a cosmetic gel.

Rheological Characteristics: Rheological characteristics of each preparation at 25"C were determined by means of a rheometer manufactured by Fudo Kogyo K.K. using a pin having a pressure area of 1 cm2 under conditions of 6 cm/min in upstroke speed of the sample holder and 5 cm/min in chart speed.

The rheological characteristic curve is shown in Fig. 1. As is clear from Fig. 1, each of the compositions of Examples 1 and 2 and Comparative Example 1 exhibiting an easily disintegrable state experienced a steep rise in stress and then an abrupt drop to a constant level.

EXAMPLES 3 TO 6 OrganolePtic Test: An organoleptic test as to feel on use was conducted by 20 panel members consisting of 12 females aged from 21 to 32 and 8 males aged from 25 to 29. Cosmetic gels having the formulation shown in Table 3 below were prepared in the same manner as described above.

TABLE 3 Compar. Compar. Compar. Compar.

Example Example Example Example Example Example Example Example 3 4 5 6 3 4 5 6 Composition (%): Monoammonium 4.0 4.0 6.0 8.0 4.0 - 6.0 8.0 glycyrrhizate Purified water 85.0 83.4 81.4 79.4 83.8 87.4 81.8 79.8 Carboxyvinyl polymer 0.3 0.3 0.3 0.3 - 0.3 - Sodium hydroxide 0.1 0.1 0.1 0.1 - 0.1 - Alcohol 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Polyoxyethylene glyceryl pyroglutamate 0.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Vitamin E 0.05 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Octyl p-dimethylaminobenzoate - 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Perfume 0.05 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Since the preparation of Comparative Example 4 was not a gel but a creamy product, it was not subjected to the organoleptic test.

Not informed of the formulation of each sample, the panel members were inquired as to the feel on use of the sample. Judgements were made with respect to five items of "easy picking on a hand", "spreadability", "feel after application", "liking", and "easy disintegrability" and each item was rated as follows: +1 for "good", 0 for "moderate", and -1 for "bad". All the points for each item were added together to obtain an overall rating. The results obtained are shown in Table 4 below.

TABLE 4 Compar. Compar. Compar. Compar.

Example Example Example Example Example Example Example Example 3 4 5 6 3 4 5 6 Easy picking on a hand 14 14 10 9 12 - 7 6 Spreadability 15 17 12 10 9 - 7 8 Feel after application 15 17 6 4 15 - 7 3 Liking 13 15 9 7 12 - 6 4 Easy disintegrability 15 18 10 5 14 - 8 1 ------------------------------------------------------------------------------------------------------------- Overall rating 72 81 44 32 62 - 29 17 As can be seen from Table 4, the cosmetics according to the present invention achieved very satisfactory results as compared with the corresponding comparative formulations having the same monoammonium glycyrrhizate content, i.e., Comparative Example 3 vs Example 3, Comparative Example 5 vs Example 5, and Comparative Example 6 vs Example 6.

Test on Long-Term Stability: Among the formulations used above, those having an overall rating with 50 points or more were further subjected to testing for long-term stability as follows.

Each sample was stored in a thermostatic vessel set at 4OC, 20 C, or 100C for 2 months. The sample was taken out of the vessel at the 1st and 2nd months and evaluated according to the following rating system.

Bad ... Fluidity of the gel was observed.

Moderate ... Slight fluidity of the gel was observed.

Good ... Fluidity of the gel was not observed.

The results obtained are shown in Table 5 below.

TABLE 5 Compar.

Term of Example Example Example Storage Temp. 3 4 3 1 month 40iC good good bad 20iC good good good lOC good good good 2 months 400C good good bad 20iC good good moderate lO'C good good good As can be seen from Table 5, the samples of Examples 3 and 4 were excellent in long-term stability whereas the sample of Comparative Example 3 using a glycyrrhizic acid compound as the sole gelling agent was inferior in long-term stability.

EXAMPLE 7 Non-Alcohol Emollient Lotion Gel: A non-alcohol cosmetic having the following composition was prepared in the same manner as in Example 1.

Component Amount (wt%) Component A: Monoammonium glycyrrhizate 4.0 Purified water 93.5 Sodium carboxymethyl cellulose 0.3 Component B: Polyoxyethylene (20) sorbitan monolaurate 1.5 Vitamin E 0.1 Squalane 0.5 Perfume 0.1 The resulting cosmetic gave a good feel on use and exhibited excellent gel stability for a long time.

EXAMPLE 8 Sunscreening Lotion Gel: A cosmetic having the following composition was prepared in the same manner as in Example 1.

Component Amount (wt%) Component A: Monoammonium glycyrrhizate 4.0 Purified water 88.1 Xanthan gum 0.3 Component B: Alcohol 5.0 Polyoxyethylene (20) sorbitan monolaurate 1.7 Vitamin E 0.1 Octyl p-dimethylaminobenzoate 0.6 Oxobenzone 0.1 Perfume 0.1 The resulting cosmetic gave a good feel on use and was excellent in long-term gel stability.

EXAMPLE 9 Sunscreening Lotion Gel (Non-Alcohol): A non-alcohol cosmetic having the following composition was prepared in the same manner as in Example 1.

Component Amount (wt%) Component A: Monosodium glycyrrhizate 5.0 Purified water 91.7 Hydroxyethyl cellulose 0.3 Component B: Polyoxyethylene (20) oleyl ether 2.0 Menthol 0.1 Vitamin E 0.1 Octyl p-dimethylaminobenzoate 0.6 Oxobenzone 0.1 Perfume 0.1 The resulting cosmetic gave a good feel on use and was excellent in long-term gel stability.

EXAMPLE 10 Beauty Lotion Gel: A cosmetic having the following composition was prepared in the same manner as in Example 1.

Component Amount (wt%) Component A: Monosodium glycyrrhizate 5.0 Purified water 85.6 Xanthan gum 0.6 Component- B: Alcohol 7.0 Polyoxyethylene glyceryl (25 E.O) pyroglutamate isostearate 1.5 Vitamin E 0.1 Tocopherol acetate 0.1 Perfume 0.1 The resulting cosmetic gave a good feel on use and was excellent in long-term gel stability.

BRIEF EXPLANATION OF THE DRAWING: Figure 1 shows rheological characteristic curves of the compositions obtained in Examples 1 and 2 and Comparative Examples 1 and 2, in which the ordinate plots stress and the abscissa, time (min).

Claims (3)

1. A cosmetic gel comprising a glycyrrhizic acid compound and a gelation accelerating high polymeric compound.

2. A cosmetic gel as claimed in Claim 1, wherein said gelation accelerating high polymeric compound is selected from the group consisting of a gum, a natural water-soluble high polymeric compound, and a synthetic high polymeric compound.

3. A cosmetic gel as claimed in Claim 1, wherein said gel further contains a surface active agent and an oil-soluble component.