JPS58110512A - Cosmetic composition - Google Patents

Abstract

PURPOSE:The titled stable composition having an adjusted pH of a system of 1.5-6, properties mild to the skin, suppressing hydrolysis at high temperature, obtained by adding a compound having a specific inductive capacity to a cosmetic composition comprising an amino acid alkyl ester salt as a base. CONSTITUTION:A cosmetic composition comprising an amino acid alkyl ester salt as a base material is blended with 5.0-50.0wt% preferably 20.0-50.0wt% compound having a specific inductive capacity at 25 deg.C of 5.0-40.0, and adjusted to pH of 1.6-6. For example, an inorganic acid such as hydrochloric acid, sulfuric acid, and organic acid such as acetic acid, tartaric acid, etc. is used as the pH adjustor. Isopropyl alcohol, propylene glycol, 1,3-butylene glycol, etc. may be cited as the compound having a specific inductive capacity of 5.0-40.0. Glycinecetyl ester hydrochloride, etc. may be cited as the base material of the cosmetic composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low hydrolyzable cosmetic composition for use as an amino acid alkyl ester salt t-base.

Amino acid alcohol ester salts derived from amino acids and higher alcohols have been widely used in recent years due to their usefulness as skin-friendly cosmetic base materials. As a result, emulsion stability deteriorates, and furthermore, viscosity decreases and phase separation occurs, resulting in negative effects on the product. Therefore, when amino acid alkyl ester salts are used as cosmetic base materials, hydrolysis is generally suppressed by adjusting the - of the system to acidity. It is difficult to say that it can be suppressed.

Generally, the acid-base catalyst rate constant, which represents the degree of hydrolysis rate of an amino acid alkyl ester salt, is expressed as follows.

K, = (fly) (OH-) (ko: non-catalytic rate constant, kI: acid catalyzed rate constant, kO
H: Alkaline catalyst rate constant) On the other hand, the acid and base catalyst constants of various esters are the values shown in the table below.

From the table above, it can be seen that for all esters, kM is larger on the J''ON side, that is, hydrolysis occurs on the alkaline side.As mentioned above, generally speaking, as the limit 1 is lowered, the hydrolysis rate tends to decrease. It is difficult to sufficiently suppress hydrolysis at high temperatures of 40°C or 50°C. The present invention was made to address these technical problems, and it The purpose is to provide a stable cosmetic composition that minimizes hydrolysis at high temperatures.

The cosmetic composition of the present invention is a cosmetic composition that uses an amino acid alkyl ester salt as a base material, and contains a compound having a dielectric constant of 5.0 to 40.0 at 25°C.
It is characterized in that it contains 0.0 weight and is adjusted to 1.5 to 6 weight.

Examples of the amino acid alkyl ester medium used as a base material in the cosmetic composition of the present invention include glycine cetyl ester hydrochloride, glycine stearyl ester hydrochloride, glycine cetyl ester hydrochloride, and glycine cetyl ester #! J? #Salt s Salt % /” Lysine behenyl ester hydrochloride, glycine hardened beef tallow ester hydrochloride, alanine cetyl ester hydrochloride, alanine stearyl ester hydrochloride, alanine behenyl ester hydrochloride,
Alanine cetostearyl ester hydrochloride, nonorin cetyl ester sulfate, z49n stearyl ester sulfate, palincetostearyl sulfate, sulfur sulfate, valine behenyl ester sulfate, leucine cetyl ester hydrochloride, leucine stearyl 7 Lyle ester hydrochloride, leucine setostearyl ester salt Wt salt, leucine behenyl ester hydrochloride, glutanic acid dicetyl ester hydrochloride, glutamic acid distearyl ester sulfate, glutamic acid dicetostearyl ester hydrochloride, glutamic acid dibehenyl ester hydrochloride, glycine Betaine cetyl ester sulfate, glycine betaine stearyl ester hydrochloride,
Glycine betaine behenyl sulfate, etc. are also mentioned. Organic acids such as P-)luenesulfonic acid and fatty acids are used.

As a compound having a relative permittivity of 5.0 to 40.0 at 25°C, isopropyl alcohol (relative permittivity 18.3
), globylene glycol (32), 1,3-butylene glycol (31), ethanol (24,3), methanol (32,6), etc., and have a special dielectric constant of 20.0 at 25°C. ~40.0 compounds are preferred. 25
Compounds with a dielectric constant of less than 5.0 at °C have no effect of inhibiting hydrolysis of amino acid alkyl ester salts, and even compounds with a dielectric constant of more than 40.0 have a small hydrolysis inhibiting effect.

The compounding amount of the compound having a dielectric constant of 5.0 to 40.0 at 25°C is 5.0 to 50.0% by weight based on the total amount of the cosmetic composition, and a particularly preferable amount is 20.0 to 50.0% by weight. 0 weight. When this amount is less than 5.0% by weight, the hydrolysis inhibitory effect of the amino acid alkyl ester salt at high temperatures is hardly observed, and when it exceeds SO,O weight%, the hydrolysis inhibitory effect remains almost constant. However, when the viscosity of the cosmetic composition becomes abnormally high, for example when applied to a skin cream,
It spreads poorly onto the skin, making it undesirable in terms of prescription.

In addition, in the cosmetic composition of the present invention, simply adding a compound having a dielectric constant of 5.0 to 40.0 at 25°C will not suppress the hydrolysis of the amino acid alkyl ester salt used as the base material. However, the effect of the present invention was not achieved until both the conditions of blending a compound with a specific dielectric constant such as 7 and adjusting the - of the system to 1.5 to 6 were satisfied. It is possible to suppress the hydrolysis of the amine acid alkyl ester salt at a certain high temperature.

The cosmetic composition of the present invention can be applied to hair cosmetics such as the above-mentioned skin cosmetics, hair conditioners, hair rinses, and hair creams.

Next, four examples of the present invention and a comparative example will be shown, and the effects of the present invention will be explained in more detail. In addition to the explanations provided by each side, the test methods adopted by each side will be explained below.

Test method (hydrolysis rate) After storing the cosmetic composition sample in a constant temperature bath at 50°C for one month, the hydrolysis rate of the amino acid alkyl ester salt contained as a base material was measured. 3 below
Based on stage evaluation criteria.

Evaluation criteria ◎: Hydrolysis rate 90-5chi Q: #5-15chi The hydrolysis rate of amino acid alkyl ester salts contained in The results are shown in the same table. As is clear from the same table, glopylene glycol, which is a compound having a dielectric constant of 32 at 25°C,
When it was included in the range of , the hydrolysis rate could be suppressed to θ~51G.

Table-1 *1 Relative dielectric constant 32 (25°C), *2 PH: 2 Test Example 2 Six types of hair cosmetics having the formulation shown in Table-2 below were prepared, and the alkyl amino acids contained in these cosmetics were evaluated. The hydrolysis rate of the ester salt was tested. The results are shown in the same table.

From the same table, it is clear that chlorophyllene glycol and glopylene glycol are 5 to 5.
It can be seen that even if 50eIk is blended, hydrolysis cannot be suppressed when - is greater than 6, and the hydrolysis rate can be suppressed to 0 to 55G only by adjusting - to 1.5 to 6.

Test Example 3 Eight types of cosmetic compositions containing compounds with various dielectric constants and having the formulation shown in Table 3 below were prepared, and the hydrolysis rate of amino acid alkyl ester salts contained in these cosmetics was tested. did. The results are shown in the same table. As is clear from the same table, the hydrolysis rate can be suppressed when 5.0 to 50.0% by weight of a compound having a dielectric constant of 5.0 to 40.0 at 25° C. is blended.

Table-3 Test examples 5.0 to 40. A cream based on an amino acid alkyl ester salt containing a compound having a dielectric constant of O (25° C.) was prepared and the hydrolysis rate of the amino acid alkyl ester salt was tested. This cream is an excellent cosmetic material with suppressed 4-hydrolysis at high temperatures.

Table-4 -7;

Claims (1)

[Claims] A cosmetic composition using an amino acid alkyl ester salt as a base material, which has a dielectric constant of 5.0 to 4 at 25°C.
A cosmetic composition containing 5.0 to 50.0% by weight of a 0.0 compound and adjusted to -1.5 to 6.