JP2686484B2 - Ultraviolet absorbent-containing microcapsules, method for producing the same, and cosmetics containing the microcapsules - Google Patents

Description

TECHNICAL FIELD The present invention relates to a microcapsule containing an ultraviolet absorber, a method for producing the microcapsule, and a cosmetic containing the microcapsule containing the ultraviolet absorber. Is.

(Prior Art) As is well known, it is known that ultraviolet rays have various effects on the skin.

That is, the ultraviolet rays in the UV-B region (290 to 320 nm) cause erythema and blisters on the skin, resulting in blackening of the skin after inflammation.

UV rays in the UV-A region (320 to 400 nm) cause almost no erythema, but UV in terms of blackening.
It is the same as the case of the ultraviolet ray of -B.

Further, ultraviolet rays cause pigmentation such as spots and freckles on the skin, or cause aging and degeneration of the skin.

Therefore, in order to solve such various problems,
Conventionally, various ultraviolet absorbers have been developed and are also contained in, for example, cosmetics.

In particular, in the case of cosmetics, there is a great demand for blocking the ultraviolet rays from the skin, and therefore, other than the above-mentioned ultraviolet absorbers (mainly organic ones such as para-aminobenzoate derivatives, benzotriazole derivatives, benzophenone derivatives, cinnamate derivatives, etc.) For example, cosmetics which prevent skin irradiation of ultraviolet rays by containing an inorganic pigment such as titanium dioxide or zinc oxide capable of reflecting ultraviolet rays are commercially available.

(Problems to be Solved by the Invention) (a) However, in the case of a cosmetic containing the organic ultraviolet absorber, the compatibility of the ultraviolet absorber with the cosmetic base and the feeling of use are not always good. It wasn't something.

Further, when applied to the skin, there is a problem that the ultraviolet absorbent itself causes irritation to the skin, and even when such an ultraviolet absorbent absorbs light energy, it causes temporary irritation to the skin.

In any case, conventional cosmetics containing an ultraviolet absorber have any of the problems described above, and therefore are limited to a specific type when actually used on the skin. It was

(B) On the other hand, in the case of a cosmetic containing the above-mentioned inorganic pigment, there is no problem with respect to skin irritation, etc., but it is not originally contained in the cosmetic with a planned UV absorbing effect. It has a drawback that it cannot block UV rays sufficiently and cannot prevent UV irradiation on the skin.

In particular, cosmetics containing an inorganic pigment having a particle size in a region that blocks visible light (having a relatively large particle size) have weak absorption in the ultraviolet region.

On the other hand, when fine particle titanium dioxide is added, the light-scattering effect provides a UV-shielding effect, but on the contrary, the light scattering causes the skin to appear whitish. Moreover, since it has poor adhesion to the skin and lacks spreadability, it adheres thickly to the skin, and thus the so-called make-up state gives a finish without transparency.

In any case, conventionally, almost no cosmetics have been developed which prevent skin irradiation of ultraviolet rays and satisfy various conditions such as safety and compatibility with the skin.

The present invention has been made in order to solve all the problems as described above, has a good effect of absorbing and shielding harmful ultraviolet rays to the skin, prevents the skin from being irradiated with ultraviolet rays, and is safe and It is an object of the present invention to provide a cosmetic which is excellent in adhesiveness to and spreadability, and is excellent in usability and transparency.

(Means for Solving the Problems) The inventors of the present invention have conducted diligent research to solve such problems, and as a result, include a certain type of organic ultraviolet absorber in a certain type of inorganic spherical fine particles. It has been found that the above-mentioned problems can be solved by microcapsuling at least and incorporating this into a cosmetic, and thus the present invention has been completed.

That is, the present invention, in order to solve the above problems, is made as a microcapsule containing an ultraviolet absorber, and a method for producing the microcapsule, and a cosmetic containing the microcapsule. General formula In the formula, m X and n Y are the same or different and each represent an alkyl group having 1 to 24 carbon atoms, an alkoxy group, a sulfonic acid group or an alkali metal salt thereof, and m and n are integers of 0 to 3. , K + 1 is an integer of 1 to 4), and the benzophenone derivative is contained in spherical fine particles containing silica as a main component and having an average particle diameter of 0.1 to 30 μm.

A feature of the method for producing microcapsules is that a benzophenone derivative having the above chemical structure is dissolved in an aqueous solution of an alkali metal silicate, and the aqueous solution and an organic solvent having a solubility of 5% or less in water and the benzophenone derivative are used. A W / O emulsion is prepared by mixing with a solvent, and then an acidic aqueous solution capable of forming a water-insoluble precipitate by the neutralization reaction with the alkali metal silicate and the alkali solution of the benzophenone derivative is added to the emulsion. The benzophenone derivative is mixed with, and if necessary, the benzophenone derivative with an average particle diameter of 0.1 to 30 containing silica as a main component.
It is intended to be manufactured by being encapsulated in spherical fine particles of μm.

Furthermore, the feature of the cosmetic is that it contains the above-mentioned microcapsules.

Examples of the benzophenone derivative represented by the above general formula include the following.

(A) 2,2'-dihydroxy-4-methoxybenzophenone (b) 2-hydroxy-4-methoxybenzophenone (c) 2-hydroxy-4-methoxybenzophenone-
5-sulfonic acid (d) 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (e) 2,2 ', 4,4'-tetrahydroxybenzophenone (f) 2,2'-dihydroxy-4,4 '-Dimethoxybenzophenone-5-sulfonate sodium (to) 2,4-dihydroxybenzophenone (thi) 2-hydroxy-4-methoxybenzophenone-
Sodium 5-sulfonate (ri) 2-hydroxy-4-octyloxybenzophenone (nu) 2-hydroxy-4'-methoxybenzophenone (l) 2-hydroxybenzophenone (wo) 4-hydroxybenzophenone (wa) 2-hydroxy- 4-methylbenzophenone (f) 2-hydroxy-5-methylbenzophenone (yo) 2,5-dihydroxybenzophenone (ta) 2-hydroxy-5-methoxybenzophenone However, the types of the benzophenone derivative in the present invention are the above (a) to It is not limited to (ta).

Further, in the method for producing a microcapsule of the present invention, examples of the alkali metal silicate include JI
Examples include S1 sodium silicate, JIS No. 2 sodium silicate, JIS No. 3 sodium silicate, sodium metasilicate, potassium silicate (K ₂ O · nSiO ₂ , n = _{2 to} 3.8).

The organic solvent used in the above-mentioned production method is an aliphatic saturated hydrocarbon such as n-hexane, decane or octane, or an aromatic hydrocarbon such as toluene, benzene or xylene,
Further, alicyclic hydrocarbons such as cyclohexane and the like can be mentioned.

Of course, these solvents may be used alone or in combination of two or more.

Further, as the emulsifier used in the production method, a nonionic surfactant having an HLB value in the range of 3.5 to 6.0 can be preferably used. Typical examples include sorbitan sesquioleate, sorbitan monooleate,
Examples include polyoxyethylene sorbitan trioleate.

Further, the acidic aqueous solution used in the production method is preferably one containing a polyvalent anion such as a sulfate ion or a phosphate ion. For example, if the above benzophenone derivative is 2,
In the case of 4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, etc., the pH after the reaction is 5 or less, especially An acidic aqueous solution of 3 or less is preferable, and the higher the concentration, the more preferable.

However, types of the alkali metal silicate, organic solvent, emulsifier, acidic aqueous solution, etc. are not limited to the above.

(Operation) (1) Regarding Preparation Mechanism FIG. 1 is an explanatory view showing a process of producing fine particles of the microcapsule of the present invention.

First, a benzophenone derivative is dissolved in an alkali metal silicate aqueous solution, and the aqueous solution and an organic solvent are mixed, and as shown in FIG. 1 (a), the benzophenone derivative and the alkali metal silicate aqueous solution are mixed. A W / O type emulsion in which the mixed solution of (1) is used as the dispersoid 1 and the organic solvent is used as the dispersion medium 2 is prepared.

 Next, this emulsion is mixed with the above acidic aqueous solution.

At this time, the following chemical reaction occurs at the interface between the dispersoid 1 and the acidic aqueous solution.

^{_{(A) SiO 3 2- + 2H}} + → SiO 2 + H 2 O (Si 2 O 5 2- + 2H + → 2SiO 2 + H 2 O) and ^{(b) R-O - +} H + → R-OH ( wherein R is In the reaction of (b), R is, for example, 2,4-
In the case of dihydroxybenzophenone, The chemical reaction at the interface in the present invention is a coprecipitation reaction in which the two chemical reactions proceed simultaneously as in the above reaction formula.

However, in terms of reaction rate, the reaction of (a) is (b)
Since the reaction proceeds faster than the reaction described above, first, the silica thin film 3 is formed at the interface, and then, with the passage of time, the interface reaction proceeds inside the inner aqueous phase, and the product 4 of the benzophenone derivative is encapsulated in the silica. The microcapsule 5 is manufactured in this state.

(2) Prevention of Elution of Encapsulated Benzophenone Derivative Since the microcapsules in which the benzophenone derivative is encapsulated in the spherical fine particles containing silica as a main component obtained by the above reaction mechanism contain a large amount of attached water, It is preferable to dry at a high temperature of 100 ° C. or higher so that the benzophenone derivative does not deteriorate. By this operation, elution of the encapsulated benzophenone derivative is suppressed as much as possible.

Further, after that, a known surface treatment such as a silicone oil treatment can be performed if necessary, and the elution of the encapsulated benzophenone derivative is suppressed.

(Example) Hereinafter, an example of the present invention will be described.

[Examples of microcapsules]

Example 1 This example is an example of a microcapsule containing 2,2 ′, 4,4′-tetrahydroxybenzophenone, which is an example of the benzophenone derivative in the present invention.

That is, the microcapsules in this example, in the spherical fine particles containing silica as a main component, 2,2 ', 4,
It was constituted by incorporating 18.22% by weight of 4'-tetrahydroxybenzophenone, and its average particle diameter is 1.8 μm.

Example 2 This example is an example of a microcapsule containing 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, which is an example of the benzophenone derivative according to the present invention.

That is, the microcapsules in this example, in the spherical fine particles containing silica as a main component, the following formula 2,2'-
Dihydroxy-4,4'-dimethoxybenzophenone 22.
The average particle size is 04% by weight.
2.2 μm.

Example 3 This example is an example of a microcapsule containing 2,4-dihydroxybenzophenone, which is an example of the benzophenone derivative in the present invention.

That is, the microcapsules in this example are composed of spherical fine particles containing silica as a main component and containing 19.5% by weight of 2,4-dihydroxybenzophenone of the above formula, and the average particle diameter thereof is 3.1 μm. Is.

Incidentally, the particle size of the microcapsules of the present invention is not limited to the above examples, the point is that the average particle size of the spherical fine particles constituting the outer wall of the microcapsules is 0.1 to 3
It may be formed to have a thickness of 0 μm.

Reference Example The ultraviolet absorption spectra of the microcapsules of Examples 1 to 3 were measured, and the sliding friction test was performed.

(1) Ultraviolet Absorption Spectra 20 parts of the sample powder of each of the above-mentioned examples was added to white petrolatum
% By weight, kneaded and dispersed sufficiently, applied between quartz plates, and made to have a thickness of 15 μm, and the ultraviolet absorption spectrum was measured.

As a result, as shown in FIG. 3, the microcapsules of each of the above-mentioned examples show an absorption spectrum corresponding to the ultraviolet absorption spectrum of the benzophenone derivative contained therein, and UV-A or UV which is problematic in relation to skin irradiation. -It shows a sufficient ultraviolet absorbing ability for ultraviolet rays in the B region.

(2) Sliding friction When the sample of each of the above-mentioned examples was thinly applied on a glass plate and further placed on a flat glass plate having a weight of 200 g placed thereon, when it was pulled horizontally, when sliding The magnitude of the force was measured, and the relative value was shown as a bar graph as shown in FIG.

As a result, it was found that the sliding friction was smaller than that of talc, sericite, red iron oxide, and titanium oxide contained in general cosmetics.

It is presumed that this is because the microcapsules have a true spherical shape and therefore have a better rolling effect (rolling property) than the above talc and the like.

[Example of manufacturing method of microcapsule]

Example 4 This example is an example of a method for producing microcapsules containing 2,2 ′, 4,4′-tetrahydroxybenzophenone of Example 1 above.

First, 4.05 g of 2,2 ′, 4,4′-tetrahydroxybenzophenone was added to 90 ml of a 1.5 mol / l sodium silicate No. 1 solution.
Pour into 150 ml of a 5% toluene solution of a mixture of sorbitan sesquioleate and polyoxyethylene sorbitan trioleate (mixing ratio 4: 1) and emulsify with a homomixer for 5 minutes to prepare a W / O type milk. Prepare a suspension.

Next, this emulsion was added with 1.2 mol / l ammonium sulfate, 0.88 m
It is poured into 450 ml of a mixed aqueous solution of ol / l sodium dihydrogen phosphate and 0.72 mol / l phosphoric acid, stirred for 1 hour and left standing overnight. After that, solid-liquid separation is performed by centrifugation, filtration, washing with water, and drying at 120 ° C.

As a result, in the spherical fine particles mainly composed of silica
2,2 ', 4,4'-tetrahydroxybenzophenone was added to 18.22
Microcapsules with an average particle size of 1.8 μm 1
9.7 g were obtained.

When the microcapsules of this example were observed with a scanning electron microscope, it was confirmed that they had a true spherical shape as shown in FIG.

Example 5 This example is an example of a method for producing microcapsules containing 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, which is an example of the benzophenone derivative of the present invention.

First, 13.5 g of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone was dissolved in 225 ml of 1.5 mol / l sodium silicate No. 1 solution, and this aqueous solution was dissolved in sorbitan sesquioleate and polyoxyethylene sorbitan trioleate. Pour 400 ml of a 4% benzene solution of the mixture (3: 1) and emulsify with a homomixer for 5 minutes to prepare a W / O type emulsion.

Next, add this emulsion to 1.5 mol / l ammonium sulfate, 0.75 m
It is poured into 1200 ml of a mixed aqueous solution of ol / l sodium dihydrogen phosphate and 0.75 mol / l phosphoric acid, stirred for 1 hour and left standing for 12 hours. After that, the same operation as in Example 4 was performed, and microspheres having an average particle diameter of 2.2 μm containing 22.04% by weight of 2,2′-dihydroxy-4,4′-dimethoxybenzophenone in spherical fine particles containing silica as a main component. 50.7 g of capsules were obtained.

Example 6 This example is an example of a method for producing microcapsules containing 2,4-dihydroxybenzophenone, which is an example of the benzophenone derivative of the present invention.

First, 10.0 g of 2,4-dihydroxybenzophenone was added to 1.
It was dissolved in 200 ml of 5 mol / l sodium silicate No. 1 solution, and this aqueous solution was mixed with sorbitan monooleate and polyoxyethylene sorbitan monooleate (mixing ratio 6:
Pour into 350 ml of the 5% n-hexane solution of 1) and emulsify with a homomixer for 3 minutes to prepare a W / O type emulsion.

Next, this emulsion was poured into 1000 ml of a mixed aqueous solution of 1.2 mol / l sodium dihydrogen phosphate and 1.8 mol / l phosphoric acid,
Stir for hours and let stand overnight. After that, the same operation as in Example 4 was performed to obtain 2, in the spherical fine particles containing silica as a main component.
45.2 g of microcapsules containing 19.52% by weight of 4-dihydroxybenzophenone and having an average particle diameter of 3.1 μm were obtained.

[Examples of cosmetics]

The microcapsules as described above can be incorporated into cosmetics, pharmaceuticals, etc. for the purpose of preventing the harmful effects of ultraviolet rays on the skin.

The content of the microcapsules of the present invention in cosmetics varies depending on the type of cosmetics, but is generally 0.1 to 20% by weight, especially 0.5 to 10% by weight as a benzophenone derivative.
It is preferable that

The cosmetic of the present invention is prepared by blending the above-mentioned microcapsules with a known cosmetic base by a conventional method to prepare various dosage forms such as creams, solutions, sticks, emulsions, foundations and ointments. It

That is, by selectively using the above-mentioned microcapsules in accordance with the cosmetic base, an oil-based cosmetic oil, an oily cream containing a large amount of an oil base, an oily emulsion, and a weak mixture containing a large amount of water are used. Manufactures all forms of cosmetics that have an ultraviolet absorbing effect, from basic cosmetics such as oily creams, weakly oily emulsions and water-based lotions to various makeup cosmetics such as oil-based foundations and lipsticks It becomes possible.

 Next, examples of the cosmetics of the present invention will be described.

Example 7 This example is an example of a cosmetic in which the microcapsules of the present invention are mixed in a so-called powder foundation.

That is, the composition of the cosmetic of this example is as follows.

Ingredients wt% Microcapsule of Example 1 30.0 Talc balance Mica 30.0 Titanium oxide 1.0 Titanium oxide 8.0 Bengala 0.7 Yellow iron oxide 1.8 Black iron oxide 0.2 Crystalline cellulose 0.2 Methylpolysiloxane 4.0 Liquid paraffin 3.0 Squalane 4.0 Perfume suitable amount Preservative, antioxidant Agent In the case of producing the cosmetics of this example, while thoroughly stirring the above-mentioned with a Henschel mixer, uniformly add the mixture of the other ingredients thereto, and treat with a crusher,
It is manufactured by compression molding.

The cosmetic of this example had a transparent feeling and adhesiveness, and was able to adhere thinly and evenly to the skin.

It was also found that the ultraviolet ray shielding effect was extremely large.

Moreover, like cosmetics containing conventional inorganic pigments,
The whitiness does not stand out.

Furthermore, a soft feeling of use was obtained and the makeup lasting property was also good.

Example 8 This example is an example of a cosmetic composition in which the microcapsules of the present invention were mixed with a W / O type emulsion foundation.

That is, the composition of the cosmetic of this example is as follows.

Ingredients% by weight Microcapsule of Example 2 10.0 Microcapsule of Example 3 10.0 Titanium dioxide 8.0 Kaolin 2.0 Talc 5.0 Solid paraffin 5.0 Lanolin 10.0 Liquid paraffin 27.0 Sorbitan sesquioleate 5.0 Purified water Remaining perfume Suitable amount Preservative, antioxidant Trace amount In order to manufacture the cosmetic of this example, first, are mixed and treated with a pulverizer to obtain a powder. Next, add a portion of the above to this powder, evenly disperse with a homomixer, heat the other components except to add to this, 70 ℃
(Oil phase). Then, is heated to 70 ° C., added to the oil phase, uniformly emulsified and dispersed with a homomixer, and cooled to 40 ° C. with stirring after stirring.

The cosmetic of this example has a great effect of blocking ultraviolet rays, and is excellent in usability and transparency.

In addition, the effect of preventing whitening from floating was excellent, and the durability of makeup was also good.

Example 9 This example is an example of a cosmetic in which the microcapsules of the present invention were mixed in a W / O cream.

That is, the composition of the cosmetic of this example is as follows.

Ingredients wt% Microcrystalline wax 11.0 Beeswax 4.0 Vaseline 6.0 Solid paraffin 5.0 Squalane 30.0 Hexadecyl adipate 10.0 Glycerin monooleate 3.0 Polyoxyethylene (20) sorbitan oleate 1.0 Propylene glycol 2.5 Microcapsule of Example 1 10.0 Purified water Remaining amount Fragrance Suitable amount Preservative, antioxidant Trace amount To manufacture the cosmetics of this example, first, and are added and heated to keep at 80 ° C. (water phase). Also, mix other ingredients, heat decompose and keep at 80 ° C (oil phase). After uniformly dispersing in the aqueous phase with a homomixer, the aqueous phase is added to the oil phase, the mixture is uniformly emulsified with a homomixer, and after the emulsification, the cosmetic is produced by stirring while cooling.

The cosmetic of this example has an excellent ultraviolet shielding effect and is more safe than conventional cosmetics.

In addition, it adheres evenly and thinly to the skin, has adhesiveness, and has excellent usability and transparency.

In addition, the effect of preventing whitening from floating was excellent, and the durability of makeup was also good.

Example 10 This example is an example of a cosmetic composition in which the microcapsules of the present invention are mixed in an O / W type cream.

That is, the composition of the cosmetic of this example is as follows.

Ingredients% by weight Beeswax 10.0 Cetyl alcohol 5.0 Hydrogenated lanolin 8.0 Squalane 32.5 Glycerin monostearate 2.0 Polyoxyethylene (20) sorbitan monolaurate 2.0 1,3-Butylene glycol 5.0 Microcapsules of Example 10 Purified water Remaining amount Fragrance Suitable amount Preservative, antioxidant Trace amount To manufacture the cosmetic of this example, first, and are added and heated to 70 ° C. (water phase). In addition, other ingredients are mixed and dissolved by heating and kept at 70 ° C (oil phase). After uniformly dispersing in the aqueous phase with a homomixer, the oil phase is added to the aqueous phase, the mixture is uniformly emulsified with a homomixer, and after the emulsification, the cosmetic is produced by stirring while cooling.

The cosmetic of this example has an excellent ultraviolet shielding effect and is more safe than conventional cosmetics.

In addition, it adheres evenly and thinly to the skin, has adhesiveness, and has excellent usability and transparency.

In addition, the effect of preventing whitening from floating was excellent, and the durability of makeup was also good.

Example 11 This example is an example of a cosmetic composition containing the microcapsules of the present invention in an emulsion.

That is, the composition of the cosmetic of this example is as follows.

Ingredients wt% Stearic acid 2.5 Cetyl alcohol 1.5 Vaseline 5.0 Liquid paraffin 10.0 Polyoxyethylene (10) monooleate 2.0 Polyethylene glycol 1500 3.0 Triethanolamine 2.0 Carboxyvinyl polymer 0.15 Microcapsules of Example 3 Purified water Remaining fragrance Suitable amount Preservatives and Antioxidants Traces To manufacture the cosmetics of this example, firstly, (i) and (ii) are added, and the mixture is heated and melted and kept at 80 ° C (aqueous phase). Also, other ingredients are mixed, heated and dissolved to keep at 80 ° C (oil phase). After homogenously dispersing in the aqueous phase with a homomixer, the oil phase is added to the aqueous phase, the mixture is uniformly emulsified with a homomixer, and after the emulsification, the mixture is cooled to 30 ° C. with stirring to produce the above cosmetic composition. It

The cosmetic of this example has an excellent ultraviolet shielding effect and is more safe than conventional cosmetics.

In addition, it adheres evenly and thinly to the skin, has adhesiveness, and has excellent usability and transparency.

In addition, the effect of preventing whitening from floating was excellent, and the durability of makeup was also good.

Example 12 This example is an example of a cosmetic composition in which the microcapsules of the present invention are blended in a lip balm.

That is, the composition of the cosmetic of this example is as follows.

Ingredients wt% Microcapsules of Example 2 3.0 Microcapsules of Example 4.0 Candelilla wax 2.9 Ceresin 14.9 Resiner 4.8 Octyldodecanol 7.0 Diisostearyl arelate 35.5 Glycerin tri-2-ethylhexanoate 22.2 Neopentyl glycol dioctanoate 5.6 Fragrance Suitable amount Preservative, Antioxidant Trace amount To manufacture the cosmetic of this example, first, is added to a part of and treated with three rollers to form a pigment part. Next, the other components are mixed and dissolved by heating, and then the above pigment part is added and uniformly dispersed by a homomixer. Then, after dispersion, the mixture is poured into a mold and rapidly cooled, and a stick-shaped product is inserted into a container for framing. In this way, the cosmetic material is manufactured.

The cosmetic of this example has an excellent ultraviolet shielding effect and is more safe than conventional cosmetics.

In addition, it adheres to the lips thinly and uniformly, and has excellent usability and transparency.

 Furthermore, the makeup durability was also good.

(Effects of the Invention) (a) As described above, in the microcapsule of the present invention, the benzophenone derivative which is an ultraviolet absorber is encapsulated in spherical fine particles containing silica as a component and having an average particle diameter of 0.1 to 30 μm. Since the UV absorber does not come into direct contact with the skin because it is composed, the irritation to the skin is reduced, and the safety is greatly increased compared to conventional UV absorbers. There is a remarkable effect.

Therefore, even a cosmetic containing such a microcapsule has an advantage that a stimulating effect on the skin can be obtained.

(B) Further, since the microcapsules themselves are powders, there is an effect that it becomes possible to easily mix them with a cosmetic base, which has been difficult to mix with conventional ultraviolet absorbers.

(C) Furthermore, since the microcapsules are spherical powders, the spreadability of cosmetics containing such microcapsules is very good as compared with conventional cosmetics containing inorganic pigments. There is an effect that it adheres thinly and evenly to the skin without sticking it thickly and does not burden the skin.

(D) Moreover, in such cosmetics, the spherical fine particles constituting the outer wall of the contained microcapsules are made of silica having a refractive index of light substantially equal to that of the oil solvent in the cosmetic base. Therefore, there is an advantage that the skin does not give the impression of being white due to the scattering of light unlike the conventional cosmetics containing titanium oxide.

(E) Further, the above-mentioned cosmetics have the advantages that they are excellent in transparency, press-fillability, and long-lasting makeup.

(F) Furthermore, in the production method of the present invention, the benzophenone derivative is dissolved in an aqueous solution of an alkali metal silicate, and the aqueous solution and an organic solvent are mixed to prepare a W / O emulsion, and then Since a method for producing microcapsules is obtained by mixing an acidic aqueous solution capable of forming a water-insoluble precipitate by a neutralization reaction of the alkali metal silicate and the alkali solubilization of the benzophenone derivative with the emulsion, the benzophenone derivative is obtained. The microcapsules can be produced by being encapsulated in spherical fine particles containing silica as a main component.

In particular, following the coprecipitation reaction at the interface ^{_{(a) SiO 3 2- + 2H}} + → SiO 2 + H 2 O (Si 2 O 5 2- + 2H + → 2SiO 2 + H 2 O) and ^{(b) R-O - +} H + → In R-OH (where R represents a benzophenone skeleton), the reaction of (a) above proceeds faster than the reaction of (b), so that the benzophenone derivative is surely included in the spherical fine particles, and thus the microcapsule There is an effect that manufacturing can be reliably performed.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manufacturing process of microcapsules. FIG. 2 is a chart of the ultraviolet absorption spectrum of the microcapsules of one example. FIG. 3 shows a graph of a sliding friction test of microcapsules of one example.

Claims (3)

(57) [Claims] (1) General formula (In the formula, m X and n Y are the same or different and each represent an alkyl group having 1 to 24 carbon atoms, an alkoxy group, a sulfonic acid group or an alkali metal salt thereof, and m and n are 0.
To 3 and k + 1 is an integer of 1 to 4), and a benzophenone derivative represented by the formula (3) is encapsulated in spherical fine particles containing silica as a main component and having an average particle diameter of 0.1 to 30 μm. Microcapsules containing UV absorbers. 2. The general formula (In the formula, m X and n Y are the same or different and each represent an alkyl group having 1 to 24 carbon atoms, an alkoxy group, or a sulfonic acid group or an alkali metal salt thereof, and m and n are 0 to 3 Benzophenone derivative represented by an integer, and k + 1 represents an integer of 1 to 4) is dissolved in an aqueous solution of an alkali metal silicate, and the solubility in the aqueous solution, water and the benzophenone derivative is 5% or less. A W / O type emulsion is prepared by mixing with an organic solvent, and then an acidic aqueous solution capable of forming a water-insoluble precipitate by the neutralization reaction with the alkali metal silicate and the alkali dissolved substance of the benzophenone derivative is added to the emulsion. Mix with the suspension, then filter if necessary,
A method for producing a microcapsule containing an ultraviolet absorber, which comprises rinsing and drying the benzophenone derivative in spherical fine particles containing silica as a main component and having an average particle size of 0.1 to 30 μm. 3. The general formula (In the formula, m X and n Y are the same or different, each represents an alkyl group having 1 to 24 carbon atoms, an alkoxy group, or a sulfonic acid group or an alkali metal salt thereof, and m and n are 0 to 3; Benzophenone derivative represented by an integer, k + 1 is an integer of 1 to 4) and microcapsules containing silica as a main component in spherical fine particles having an average particle diameter of 0.1 to 30 μm. Cosmetics characterized by that.