JPH04295409A - Skin protective agent - Google Patents

Abstract

PURPOSE:To obtain a skin protective agent, containing a silicone/acrylic copolymer, a specific cyclic dimethylpolysiloxane and a lower alcohol, homogeneously applicable and having excellent touch and improved ultraviolet ray protective and humectant effects. CONSTITUTION:A skin protective agent is composed of a silicon/acrylic copolymer, e.g. a copolymer obtained by copolymerizing a silicon-containing monomer expressed by formula I [X is radically polymerizable group; R<1> is 1-20C hydrocarbon, halogenated hydrocarbon, etc.; R<2> is 1-20C hydrocarbon, etc.; (m) is 1-10; (n) is 5-100] with an alkyl acrylate, an alkyl methacrylate and a carboxyl group- containing monoethylenically unsaturated monomer, a cyclic dimethylpolysiloxane expressed by formula II [(a) is 1-8] and an alcohol (e.g. preferably the alcohol such as methanol or ethanol). The aforementioned skin protective agent is in the form of a solution prepared by dissolving 5-15wt.% silicone/acrylic copolymer in a mixed solvent composed of 3-20wt.% cyclic dimethylpolysiloxane and 65-90wt.% alcohol.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a skin protective agent comprising a silicone/acrylic copolymer, a cyclic dimethylpolysiloxane and an alcohol.

0002

2. Description of the Related Art In order to protect the skin from irritating substances, skin protective agents containing polymeric substances having film-forming ability have been developed. However, conventional skin protectants have the disadvantage of poor feel and moisturizing properties. On the other hand, cyclic dimethylpolysiloxane is used in the hair care field and in cosmetic creams as a substance that provides good texture and moisturizing properties. Cyclic dimethylpolysiloxane is
It is stable, causes little skin irritation, is non-sticky, and gives a refreshing feeling.

[0003] Generally, however, when a skin protective agent contains cyclic dimethylpolysiloxane, the film-forming substance is not uniformly compatible with the cyclic dimethylpolysiloxane at room temperature;
The drawback is that the skin protectant cannot be applied evenly. Another disadvantage is that the cyclic dimethylpolysiloxane evaporates in the formed film in a short period of time, and the properties of the cyclic dimethylpolysiloxane, such as good feel, UV protection effect, and moisturizing properties, do not last for a long time.

0004

SUMMARY OF THE INVENTION An object of the present invention is to provide a skin protective agent that can be applied uniformly, has an excellent feel, an excellent ultraviolet protection effect, and an excellent moisturizing property.

[0005]

[Means for Solving the Problems] The gist of the present invention is (i)
Silicone/acrylic copolymer, (ii) general formula:

embedded image [where a is a number from 1 to 8]. ] and (iii) alcohol.

Silicone/acrylic copolymers are produced by polymerizing a silicon-containing monomer having one radically polymerizable group in the molecule, an alkyl (meth)acrylate, and a monoethylenically unsaturated monomer containing a carboxyl group. can be obtained. The silicone/acrylic copolymer has, for example, the general formula (A):

[In the above formula, X is a radically polymerizable group;

embedded image (R3 is the same or different and is a hydrocarbon group or halogenated hydrocarbon group having 1 to 20 carbon atoms, p is a number of 5 to 100), and among all R1, Y is The number of groups is 0
, 1 or 2. ), R2 is a hydrocarbon group or halogenated hydrocarbon group having 1 to 20 carbon atoms, m is a number from 1 to 10, and n is a number from 5 to 100. ] 1 to 30% by weight of a silicon-containing monomer, (B) 30 to 70% by weight of an alkyl acrylate, (C) 0 to 30% by weight of an alkyl methacrylate, and (D) a carboxyl group-containing monoethylenic monomer. It is a copolymer obtained by polymerizing 5 to 45% by weight of an unsaturated monomer.

In component (A), X is, for example,

[C5
] etc. Particularly preferable examples of X include methacryloxy group and acryloxy group.

[0008] m is a number from 1 to 10, preferably a number from 1 to 6, and more preferably 3. When m is larger than 10, the effect of silicone (organopolysiloxane) is hindered.

Examples of R1 being a hydrocarbon group or a halogenated hydrocarbon group include a methyl group, an ethyl group, a phenyl group, a trifluoropropyl group, and preferably a methyl group. An example where R1 is Y is

[C6] (p=5 to 100, preferably 5 to 50).

[0010] n is a number from 5 to 100, preferably from 5 to 5
It is the number of 0. If there is less organopolysiloxane,
Characteristics such as functionality, lubricity, and water repellency will not be exhibited, and if too much, film-forming properties, solubility, and adhesion to other substances will be lost.

R2 is, for example, a methyl group, an ethyl group, a phenyl group, a trifluoropropyl group, etc., and is preferably a methyl group.

[0012] Component (A) is, for example,

[Chemical 7] It is.

[0013] By incorporating component (A) into the copolymer, ease of spreading when applied on the skin,
When applying it, you can get a good feel after applying it. Ingredients (A
) is 1% based on the total weight of components (A) to (D).
-30% by weight, preferably 3-20% by weight, more preferably 5-15% by weight. The amount of component (A) is 1% by weight
When the amount is less than 30% by weight, sufficient lubricity cannot be obtained in the film, and when it is more than 30% by weight, it becomes difficult to produce the copolymer. The higher the content of component (A) in the copolymer, the higher the retention of cyclic dimethylpolysiloxane in the film.

Component (B) is an alkyl acrylate, preferably an acrylate ester of an alkyl having 1 to 6 carbon atoms,
Particularly preferred are ethyl acrylate, propyl acrylate and butyl acrylate. The amount of component (B) is 30 to 70% by weight based on the total weight of components (A) to (D),
Preferably it is 50 to 65% by weight. When the amount of component (B) is less than 30% by weight, the flexibility of the film is insufficient and it becomes difficult to dissolve in ordinary solvents, and when it is more than 70% by weight, film formation is insufficient.

Component (C) is an alkyl methacrylate, preferably a methacrylic ester of an alkyl having 1 to 6 carbon atoms, particularly preferably methyl methacrylate and ethyl methacrylate. The amount of component (C) is the amount of components (A) to (D
), preferably 1 to 30% by weight based on the total weight of
It is 30% by weight. When the amount of component (C) is more than 30% by weight, the film becomes hard.

Since alkyl acrylate is flexible and alkyl methacrylate is hard, the rigidity and flexibility of the film can be adjusted over a wide range by using both components in combination.

Component (D) is a carboxyl group-containing monoethylenically unsaturated monomer, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, maleic acid half ester, fumaric acid half ester, etc. Component (D) further enhances the adhesion to the skin, reduces electrostatic charge, and provides swelling or dispersibility in weak alkalis such as amines and aqueous ammonia, thereby further facilitating the removal of the copolymer. make it easier. The amount of component (D) is from component (A) to (D
), preferably 10 to 45% by weight based on the total weight of
-40% by weight, more preferably 10-20% by weight. If the amount of component (D) is less than 5% by weight, the film cannot be easily removed. When the amount is more than 45% by weight, water repellency and water resistance decrease, and the film becomes hard.

[0018] The silicone/acrylic copolymer can also be copolymerized with monomers other than the above-mentioned components. Examples of other monomers are vinyl monomers such as vinyl acetate, 2-hydroxyethyl methacrylate, N-vinylpyrrolidone. The amount of other monomers is preferably 20 parts by weight or less based on 100 parts by weight of the total weight of components (A) to (D) so as not to impair the effects of the present invention.

The weight average molecular weight of the silicone/acrylic copolymer is usually 50,000 to 13,000 as measured by GPC method.
00,000, preferably 100,000 to 800,000.

The silicone/acrylic copolymer can be easily produced from the above-mentioned monomers by a commonly known polymerization method. The polymerization method may be either solution polymerization or emulsion polymerization. As an example, solution polymerization involves, in the presence of a medium,
The monomer is heated and stirred in the presence of a polymerization initiator. Examples of the medium include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, ethylene glycol monoalkyl ether, and the like. The polymerization initiator is, for example, an oil-soluble polymerization initiator such as dibenzoyl peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, and azobisisobutyronitrile.

Emulsion polymerization is carried out by heating and stirring a dispersion liquid consisting of water, an emulsifier, a water-soluble polymerization initiator, and a monomer. The emulsifier is preferably an anionic or nonionic surfactant, such as sodium lauryl sulfate, sodium lauroyl sarcosine, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate, sorbitan sesquioleate, glyceryl monostearate. , sucrose fatty acid ester, etc. Examples of water-soluble polymerization initiators include ammonium persulfate, potassium persulfate, hydrogen peroxide, and t-butyl hydroperoxide, and sometimes a reducing agent such as sodium bisulfite or L-ascorbic acid may be used in combination. .

The amount of silicone/acrylic copolymer is from 1 to 30% by weight, preferably from 3 to 20% by weight, more preferably from 5 to 15% by weight, based on the weight of the skin protectant. If the amount of silicone/acrylic copolymer is more than 30% by weight, the feel during application will be poor.

In the cyclic dimethylpolysiloxane, a
is preferably 1 to 6, more preferably 1 to 4, especially 2 to
It is 3. The amount of cyclic dimethylpolysiloxane is from 0.1 to 50% by weight, preferably from 1 to 30% by weight, more preferably from 3 to 20% by weight, based on the weight of the skin protectant. When the amount is less than 0.1% by weight, moisture retention is insufficient. When the amount is more than 50% by weight, the tensile tension of the film is low.

The alcohol is preferably a lower alcohol, more preferably a lower monohydric alcohol. Particularly preferred alcohols are ethanol or isopropanol. The amount of alcohol is from 20 to 98.9% by weight, preferably from 50 to 98.9% by weight, based on the weight of the skin protectant.
96% by weight, more preferably 65-90% by weight.

The skin protective agent of the present invention is in the form of a solution in which a silicone/acrylic copolymer is dissolved in a mixed solvent consisting of cyclic dimethylpolysiloxane and alcohol. The alcohol solution of silicone/acrylic copolymer is
It may be used as a skin protectant by simply adding cyclic dimethylpolysiloxane, but preferably water, ethylene glycol, or a hydrocarbon solvent (
For example, n-hexane), etc. are added, and to the emulsion polymerization solution, an acid, an aqueous salt solution such as sodium sulfate, calcium chloride, etc. are added to precipitate the copolymer, and after washing, purification, and drying, the solid copolymer is Cyclic dimethylpolysiloxane and alcohol are added to the skin protectant.

[0026] Other resins can be easily incorporated into the skin protective agent.
Addition of cellulosic derivatives such as ethyl cellulose, hydroxypropyl cellulose, etc. is useful for improving film properties.

[0027] The film formed by the copolymer is resistant to stains such as edible oil, oil mist, food (eg, ketchup, sauce, soy sauce), ink, crayon, marker ink, etc., or is easily removed. The film can be completely removed with weak alkaline water or ethanol.

[0028]

PREFERRED EMBODIMENTS OF THE INVENTION The present invention will be specifically explained below with reference to Production Examples, Examples, and Comparative Examples. Production Example Preparation of Copolymer A A copolymer having the following monomer composition was produced by solution polymerization in ethyl acetate using diisopropyl peroxydicarbonate as a catalyst. A closed reactor equipped with a stirrer was purged with nitrogen, 75 parts by weight of ethyl acetate was charged, and the temperature inside the reactor was adjusted to 55°C. 1.0 parts by weight of diisopropyl peroxydicarbonate was added, and then the following monomers were added. mixture■
silicon-containing monomer
10 parts by weight ■ Methyl methacrylate (MMA)
15〃■Ethyl acrylate (EA
) 60 〃■Methacrylic acid (MAA) 15
〃 and 100 parts by weight of 0.5% diisopropyl peroxydicarbonate ethyl acetate solution were added to the reactor.
The addition was carried out over a period of 4 hours while maintaining the temperature. Stirring was continued in the reactor at 55°C for 2 hours and then at 77°C for 3 hours to complete the reaction, and the mixture was cooled to room temperature. The above reaction solution was placed in a mixer, and 1000 parts by weight of n-hexane was gradually added while stirring with shear to precipitate a copolymer, which was filtered, washed with n-hexane, and dried. The yield of copolymer was 94%. The weight average molecular weight of the copolymer by GPC is 12.
It was 2 x 104. This copolymer was dissolved in ethanol at a concentration of 30% to obtain a clear solution.

Preparation of copolymers B to E Copolymers were prepared by repeating the same procedure as in Example 1 except for using the monomers shown in Table 1.
A 30% ethanol solution of E was obtained.

[0030]

[Table 1]

Example 1 30% of silicone/acrylic copolymer (copolymer A)
Cyclic dimethylpolysiloxane (
KF994 manufactured by Shin-Etsu Chemical Co., Ltd., 20 g of the compound represented by chemical formula 2 (a=2)) and 50 g of ethanol were added and mixed with stirring at room temperature for 1 hour to prepare a skin protective agent. The dissolution uniformity of the skin protective agent and the residual rate of cyclic dimethylpolysiloxane were measured, and the results are shown in Table 2, FIG. 1, and FIG. 2.

[0032] The dissolution uniformity of the skin protective agent and the residual rate of cyclic dimethylpolysiloxane were measured as follows. 1) Uniformity of dissolution After the skin protective agent was left in an atmosphere at 5°C and 25°C for one day, the state of dissolution was visually confirmed. ○: Transparently dissolved △: Cloudy dispersion ×: Separated

2) Residue rate of cyclic dimethylpolysiloxane Approximately 0.5 g of the skin protectant was accurately weighed on a Petri dish with a diameter of 43 mm, and this was placed on a water bath kept at 37°C. After a certain period of time, the cyclic dimethylpolysiloxane The residual rate of siloxane was measured by gas chromatography. Note that the residual rate was also measured for only cyclic dimethylpolysiloxane, and the results are shown in FIG.

Example 2 30% of silicone/acrylic copolymer (copolymer A)
Cyclic dimethylpolysiloxane (
30 g of KF994) and 40 g of ethanol were added and mixed with stirring at room temperature for 1 hour to prepare a skin protectant. The dissolution uniformity of the skin protective agent was measured and the results are shown in Table 2.

Example 3 A skin protective agent was prepared in the same manner as in Example 1, except that Copolymer B was used as the silicone/acrylic copolymer. The dissolution uniformity and the residual rate of cyclic dimethylpolysiloxane were measured, and the results are shown in Table 2 and FIG. 2.

Examples 4 and 5 A skin protective agent was prepared in the same manner as in Example 1, except that Copolymer C (Example 4) and Copolymer D (Example 5) were used as silicone/acrylic copolymers. was prepared. The dissolution uniformity was measured and the results are shown in Table 2.

Examples 6 to 8 Except for using copolymer B (example 6), copolymer C (example 7), and copolymer D (example 8) as silicone/acrylic copolymers, A skin protectant was prepared in the same manner as in Example 2. The dissolution uniformity was measured and the results are shown in Table 2.

Comparative Example 1 20 g of cyclic dimethylpolysiloxane (KF994) and 50 g of ethanol were added to 30 g of a 30% ethanol solution of acrylic copolymer E, and the mixture was stirred and mixed at room temperature for 1 hour to prepare a skin protection agent. The dissolution uniformity and residual rate of cyclic dimethylpolysiloxane of this skin protective agent were measured, and the results are shown in Table 2, FIG. 1, and FIG. 2.

Comparative Example 2 A skin protective agent was prepared in the same manner as in Example 2, except that acrylic copolymer E was used instead of silicone/acrylic copolymer A. Measuring the dissolution uniformity of skin protectants,
The results are shown in Table 2.

[0040]

[Table 2]

[0041]

Effects of the Invention The skin protective agent of the present invention is a homogeneous solution, has good stability, and can be applied uniformly to the skin. The formed film has good water resistance, acid resistance, and irritant blocking effects. In addition, in the formed film, the cyclic dimethylsiloxane is well retained for a long period of time, so the properties of the cyclic dimethylsiloxane, such as good feel, UV protection effect, and moisturizing properties, especially good moisturizing properties, are maintained for a long time. Lasts for a long time.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the elapsed time and the residual rate of cyclic dimethylpolysiloxane in Example 1 and Comparative Example 1.

FIG. 2 is a graph showing the relationship between the proportion of silicon-containing monomer in a copolymer and the residual rate of cyclic dimethylpolysiloxane.

Claims (2)

[Claims] Claims 1: (i) silicone/acrylic copolymer; (ii) general formula: [Formula 1] [wherein a is a number from 1 to 8]; A skin protective agent comprising a cyclic dimethylpolysiloxane represented by the following formula, and (iii) alcohol. 2. Based on the weight of the skin protective agent, the amount of silicone/acrylic copolymer is 1 to 30% by weight, the amount of cyclic dimethylpolysiloxane is 0.1 to 50% by weight, and the amount of alcohol is 20 to 30% by weight. The skin protective agent according to claim 1, which is 98.9% by weight.