JPH11302146A - External preparation for skin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject external preparation having proper viscosity, uniformly applicable to the skin, having an excellent feeling in use, by including a specific lower alcohol, water and a salt of a copolymer of acrylic acid and an alkyl methacrylate. SOLUTION: This cosmetic contains (A) 40-90 wt.% of a lower alcohol (especially preferably ethyl alcohol), (B) preferably 10-59.95 wt.% of water and (C) 0.05-5 wt.% of a salt of a copolymer of acrylic acid and an alkyl methacrylate. The pH of the external preparation is preferably 5.5-7.5, especially preferably 6-7. The external preparation for skin is produced by dissolving or dispersing the copolymer of acrylic acid/the alkyl methacrylate into water or an aqueous solution of the lower alcohol, adding the residual lower alcohol and then neutralizing the solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a gel-like external preparation for skin which contains a large amount of lower alcohol, has a suitable viscosity, can be uniformly applied on the skin, and has excellent usability.
In particular, the present invention relates to a gel-like external preparation for skin which is suitable as a non-washable type of skin disinfecting composition.

[0002]

2. Description of the Related Art As a method for thickening a lower alcohol aqueous solution, carboxyvinyl polymer, polyacrylic acid,
Eudragit (methacrylic acid, alkyl methacrylate, quaternary ammonium methacrylate, alkyl acrylate and aminoalkyl methacrylate)
A method using a thickener such as polyvinylpyrrolidone, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, carrageenan and locust bean gum, and a clay mineral such as bentonite is known.

[0003] However, many of these thickeners cannot provide a sufficient thickening effect when the content of alcohol is large, so that they are difficult to use by dripping when applied on the skin and to dry. There was a problem of stickiness. The carboxyvinyl polymer, polyacrylic acid and Eudragit were excellent in the thickening effect, but were similar in that they were sticky when dried. Furthermore, when these conventionally used thickeners are blended in a large amount in order to obtain a sufficient thickening effect, they become solid like a pudding, and it is difficult to spread them evenly on the skin. .

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a gel-like skin which has an appropriate viscosity that does not cause dripping despite its high alcohol concentration, can be applied uniformly on the skin, and does not stick when dried. It is intended to provide an external preparation.

[0005]

Means for Solving the Problems The present inventors use a copolymer of acrylic acid and alkyl methacrylate as a thickening agent to increase the viscosity of the gel to a liquid gel suitable for application to the skin. We have found that we can do this and completed the present invention.

That is, the present invention relates to a method for preparing a lower alcohol 40 to 90
It is intended to provide a gel-like skin external preparation characterized by containing, by weight, water and a salt of a copolymer of acrylic acid and alkyl methacrylate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the term "gel" refers to a transparent or translucent preparation having an appropriate viscosity, and the viscosity is such that it does not drip and can be uniformly applied to the skin. From 3,000 to 12,000 cps, especially 5,000
Preferably, it is 0 to 10,000 cps.

Examples of the lower alcohol include ethyl alcohol and isopropyl alcohol, and from the viewpoint of safety and smell, ethyl alcohol is particularly preferable.

The amount of the lower alcohol is preferably 40 to 90% by weight, more preferably 50 to 80% by weight, particularly preferably 60 to 70% by weight in the external preparation of the present invention. If the lower alcohol content is less than 40% by weight, the drying speed after application becomes slow and the germicidal effect becomes insufficient. If the lower alcohol content exceeds 90% by weight, the drying speed becomes too fast and the skin becomes more irritating.

The amount of water in the composition of the present invention is from 10 to 10 in that the copolymer of alkyl methacrylate and acrylic acid can be uniformly dispersed, a uniform gel can be obtained by neutralization, and the feeling of use is good. 59.95% by weight, especially 20-40% by weight, is preferred.

As a salt of a copolymer of acrylic acid and alkyl methacrylate (hereinafter referred to as "acrylic acid / alkyl methacrylate copolymer salt"), for example, a salt of a polymer having the following structure is preferable. It is listed as.

[0012]

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[Wherein, R represents an alkyl group having 10 to 30 carbon atoms, and X and Y represent mol% of each unit in the copolymer.
Where X = 80.0 to 99.9 mol% and Y = 0.1 to 20.0 mol%. ]

Examples of commercially available acrylic acid / alkyl methacrylate copolymers include Carbopol ET.
D2020, Ultrez10, Pemulen TR-1, Pemulen TR-2 (BF
Goodrich Co., Ltd.).

The acrylic acid / alkyl methacrylate copolymer is neutralized with a base and used as a salt. As the neutralizing agent, alkanolamines, especially triethanolamine, aminomethylpropanolamine, etc. are preferably used. preferable. When neutralization is performed using a basic substance containing a metal ion such as sodium hydroxide or potassium hydroxide, the acrylic acid / alkyl methacrylate copolymer tends to precipitate as a metal salt. Accordingly, alkanolamine salts such as triethanolamine salt and aminomethylpropanolamine salt are preferable as the salt.

The amount of the acrylic acid / alkyl methacrylate copolymer salt is from 0.05 to 5% by weight, preferably from 0.1 to 3% by weight, more preferably from 0.1 to 3% by weight, in the external preparation of the present invention, since an appropriate viscosity is obtained.
0.2-1% by weight is preferred.

The gel-like external preparation for skin of the present invention may contain, in addition to the above-mentioned lower alcohol, water and a salt of acrylic acid / alkyl methacrylate copolymer, a fragrance, an anti-inflammatory, a bactericide, an astringent, a humectant, An extract or the like can be blended. In particular, if a bactericide such as chamomile extract is added, the bactericidal effect can be further enhanced. When a compound that generates cations such as Na ⁺ , K ⁺ , Ca ²⁺ by ionization (sodium chloride, potassium chloride, etc.) is added, as in the case of neutralization with sodium hydroxide, alkyl acrylate / alkyl methacrylate is added. It is desirable not to add such a compound because the copolymer is likely to precipitate as a salt of these metals.

The pH of the gel external preparation for skin of the present invention is preferably from 5.5 to 7.5, particularly preferably from 6 to 7, from the viewpoint of stability.

The skin external preparation of the present invention can be produced by dissolving or dispersing an acrylic acid / alkyl methacrylate copolymer in water or an aqueous lower alcohol solution, adding the remaining lower alcohol, and then neutralizing the resulting mixture.

The gel-like external skin preparation of the present invention thus obtained has an action of disinfecting the skin by the lower alcohol contained in a large amount and, when used, is applied uniformly to the skin without dripping. Yes, no stickiness when drying. The gel-like skin external preparation of the present invention is a skin cosmetic,
It can be applied to any of the external preparations, and is particularly suitable as a non-rinsing type skin disinfecting composition.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Examples 1 to 5 and Comparative Examples 1 to 3 The gel compositions for disinfecting the skin of the type shown in Table 1 were prepared, and their viscosity was increased, their elongation on the skin, and the stickiness when dried. Was evaluated according to the following method.
The results are shown in Table 1.

(Evaluation Method) Ten panelists took 1 g of each gel composition on their fingers, spread them with both hands, dried them without washing, and evaluated them according to the following criteria. Table 1 shows the most frequently evaluated.

Evaluation Criteria: Thickening ○: Increase in viscosity due to the incorporation of a thickener was observed, and no dripping occurred, making it suitable for use. Δ: A slight increase in viscosity due to the incorporation of the thickener was observed, but the liquid dripped. ×: No increase in viscosity due to the addition of the thickener was observed.

Elongation on the skin ：: Uniform application on the skin. ×: Elongation was partially poor and uniform application was not possible.

-Stickiness at the time of drying O: No stickiness when the alcohol evaporates after application. ×: Sticky when the alcohol evaporates after application.

[0027]

[Table 1]

As is evident from Table 1, when carboxyvinyl polymer or Eudragit was used as a thickening agent, the viscosity and elongation were good, but there was stickiness when drying, and the carboxyvinyl polymer showed thickening. While it is hard to grow and sticky when dry,
The product of the present invention using the acrylic acid / alkyl methacrylate copolymer salt was excellent in thickening, elongation and non-stickiness, and was excellent in usability.

[0029]

EFFECTS OF THE INVENTION The gel-like external preparation for skin of the present invention has an appropriate viscosity without dripping despite its high alcohol concentration, can be applied uniformly on the skin, and has no stickiness when dried. It is particularly useful as a non-rinsable type of skin disinfecting composition.

Claims (4)

[Claims] 1. A gel-like external preparation for skin comprising 40 to 90% by weight of a lower alcohol, water and a salt of a copolymer of acrylic acid and alkyl methacrylate. 2. The salt of a copolymer of acrylic acid and alkyl methacrylate is an alkanolamine salt.
The gel-like external preparation for skin according to the above. 3. The gel-like external preparation for skin according to claim 1, wherein the pH is 5.5 to 7.5. 4. The gel-like external preparation for skin according to any one of claims 1 to 3, which is a composition for disinfecting the skin which is not washed away.