JP3073887B2 - External preparation for skin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external preparation for skin which has an excellent ultraviolet protection effect and transparency, has no whitening after application, and is excellent in moisturizing properties, durability and feeling of use.

[0002]

2. Description of the Related Art Conventionally, zinc oxide and titanium oxide have been widely used as UV protection materials from the viewpoints of high sustainability and safety, and are widely used as components for cosmetics and paints. Among them, zinc oxide is particularly useful as an inorganic ultraviolet protection material because it has absorption not only in the UV-B region but also in the UV-A region. It is desired that the UV protection material be transparent in the visible region and have a strong UV protection power from the application. As such a material, finely divided zinc oxide having a particle size of 0.1 μm or less is known. However, this zinc oxide has a problem that dispersibility is poor due to easy aggregation and it is difficult to mix it into cosmetics and paints. When it is mixed, zinc oxide has poor elongation and is not practical.

[0003] In order to solve such a problem, a particle size of 0.1 to 1 µm is used to prevent agglomeration, and by forming flaky (plate-like) particles, an excellent feeling is obtained even when blended in cosmetics. And a plate-like zinc oxide powder that is transparent and absorbs ultraviolet light has been proposed (Japanese Patent Laid-Open Publication No. 1-2).
No. 30431). However, this plate-like zinc oxide powder has not been sufficiently satisfactory in terms of the effect of preventing ultraviolet rays and transparency.

Further, an aqueous solution containing zinc and a doping element (tin, aluminum, indium) is neutralized with an alkali,
A method has also been proposed in which a precipitate is formed and then heat treated at 400 to 700 ° C. (see Japanese Patent Application Laid-Open No. 2-169885). However, this method also requires heat treatment at a high temperature, and at that time, the flaky form is broken, the thickness of the particles is increased, and aggregates that cannot be dispersed are generated. Therefore, it is not suitable as a cosmetic ingredient.

Further, JP-A-6-72821 and JP-A-6-80421 disclose an average transfer diameter of 1 to 100.
A flaky zinc oxide powder containing aluminum and / or iron in a flaky zinc oxide having a volume resistivity of at least 10 6 Ωcm is disclosed. However, the purpose of this powder is to improve the mechanical strength, and even if flaky zinc oxide powder having an average diameter of 1 to 100 μm and aluminum and / or iron are mixed and fired, UV protection is not possible. It does not contribute to the effect or the transparency of the visible part.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems and is excellent in ultraviolet protection and transparency.
An object of the present invention is to provide a skin external preparation which does not cause whitening after application and has excellent moisturizing properties, sustainability and feeling upon use.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, combined a flaky zinc oxide powder having a specific shape with a specific element having +2 or more valence, In addition, it has been found that a powder having a specific light transmittance can be used to obtain a skin external preparation having an excellent ultraviolet protection effect and transparency, no whitening after application, and an excellent feeling upon use. Was completed.

[0008] That is, the present invention provides an average particle size of 0.1 µm
A flaky zinc oxide powder having an average particle thickness of 0.01 to 0.2 μm and an average plate-like ratio of 3 or more, excluding zinc integrated with the flaky zinc oxide powder and an element having a valence of +2 or more, 0.005 to 1.0 with respect to 100 mol of zinc
Molar content, 70% light transmittance at 500nm
It is intended to provide a skin external preparation characterized by containing the powder described above (hereinafter, this powder is referred to as “element-holding zinc oxide powder”).

Hereinafter, the present invention will be described. In the present invention, “integral” means that a very small amount of element having a valence of +2 or more binds to the surface of flaky zinc oxide powder as a base particle or to the inside thereof.・ It means that it is held. Therefore, the average particle diameter, the average particle thickness, and the average plate-like ratio of the flaky zinc oxide powder as the base particles and the element-holding zinc oxide powder in which the element having +2 or more valence is bonded and held as described above. value is,
The ranges are substantially the same.

The flaky zinc oxide powder constituting the element-holding zinc oxide powder has the following specific ranges of average particle size, average particle thickness, and average plate ratio. The average particle size is 0.1 μm or more and less than 1 μm, preferably 0.1 μm.
It is 1 to 0.8 μm, more preferably 0.2 to 0.7 μm. When the average particle size is less than 0.1 μm, the particles are aggregated to reduce the dispersibility, and when the average particle size is 1 μm or more, the transparency and the ultraviolet absorption are reduced. Average particle thickness is 0.01 to 0.2
μm, preferably 0.01 to 0.15 μm, more preferably 0.015 to 0.1 μm. When the average particle thickness is less than 0.01 μm, the flaky form is easily broken, and when the average particle thickness is more than 0.2 μm, it is not practical because it causes discomfort when incorporated into cosmetics. The average plate ratio is 3 or more, preferably 5 or more, and more preferably 1 or more.
0 or more. When the plate ratio is less than 3, the transparency is reduced. In the present invention, the average particle diameter is determined as the arithmetic mean of the major axis and the minor axis from the transmission electron micrograph, and the plate ratio is also obtained by reading the plate thickness from the transmission electron micrograph and calculating the average particle diameter / It is determined as the average grain thickness.

Examples of the element having a valence of +2 or more excluding zinc constituting the element-holding zinc oxide powder include iron, zirconium, calcium, germanium, manganese, magnesium, and yttrium. These may be used alone or in combination of two or more. They can be used in combination. Of these, iron, zirconium, and magnesium are preferred because of their good optical properties. When these elements are used in combination, zirconium and iron, zirconium and magnesium, iron and magnesium, iron and calcium,
A combination of magnesium and germanium is preferred.

The content of the element having a valence of +2 or more is 0.005 to 0.005 mol per 100 mol of zinc in the flaky zinc oxide powder.
1.0 mol, preferably 0.01 to 0.5 mol. When the content is less than 0.005 mol, the improvement in ultraviolet protection is small, and when it exceeds 1.0 mol, the ultraviolet absorption is rather reduced. Note that the content of the element having a valence of +2 or more can be determined by dissolving the powder in an acid or alkali solution that dissolves the contained element, and performing IPC emission analysis or the like.

The element-holding zinc oxide powder has a thickness of 500 nm.
Is required to be 70% or more, preferably 80% or more. If the light transmittance is less than 70%, whitening occurs, which is unsuitable as an external preparation component.

The method for producing the element-holding zinc oxide powder used in the present invention is not particularly limited. For example, the following first step to third step;
First, a water-soluble alkali metal salt is added and dissolved in water by adding 0.05 to 1.0 mol of a salt containing +2 or more valent element other than zinc and 0.05 to 1.0 mol based on the amount of zinc. Step 1 Add the alkaline solution to the solution obtained in the previous step
It can be manufactured according to the second step of adding the precipitate in ~ 300 seconds to form a precipitate at a pH of 11 or more, and the third step of collecting and heating and drying the precipitate formed in the previous step after aging if necessary. .

First, in the first step, a zinc salt, a salt containing an element having a valence of +2 or more other than zinc, and a water-soluble alkali metal salt are dissolved in water. Examples of the zinc salt used in this step and a salt containing an element having a valence of +2 or more other than zinc include:
These sulfates, nitrates or chlorides can be exemplified. The water-soluble alkali metal salt is a component for obtaining an element-holding zinc oxide powder that hardly causes aggregation, and examples thereof include sodium sulfate, potassium sulfate, sodium chloride, and potassium chloride. Also, a sulfuric acid aqueous solution or the like can be used instead of water.

The amount of the element having a valence of +2 or more is 10
The amount is 0.005 to 1.0 mol, preferably 0.01 to 0.5 mol, per 0 mol. The amount of the water-soluble alkali metal salt used is 0.05 to 1.0 with respect to the amount of zinc.
Mole, preferably 0.1 to 0.5 mole.

In the second step, an alkaline solution is added to the solution obtained in the previous step under vigorous stirring to adjust the pH to 11 or more, and a precipitate is formed. The alkaline solution is 1 to 300
Seconds, preferably 1 to 60 seconds, under strong stirring, for example, about 2000 to 800 when using a homomixer type stirrer.
Add under stirring at a stirring speed of 0 rpm. Addition time 3
When the time exceeds 00 seconds, when stirring is not performed, or when stirring is slow, a desired element-holding zinc oxide powder cannot be obtained, and a trace element having a different precipitation pH from zinc is precipitated simultaneously with zinc. And it becomes difficult to keep the trace elements uniform in zinc. The temperature at the time of precipitation generation in this step is preferably 60 ° C or lower, more preferably 40 ° C or lower. If the temperature is higher than 60 ° C., zinc oxide, which will eventually become base particles in the element-holding zinc oxide powder, is not easily formed into flakes and tends to be spherical or massive particles, which is not preferable.

In the third step, after aging treatment, if necessary, the precipitate is collected and dried by heating. The ripening treatment is performed by maintaining the mixture after the precipitation, while heating as necessary. In this treatment, it is preferable to carry out the treatment at about 60 to 100 ° C. for 30 minutes to 5 hours to obtain an element-holding zinc oxide powder having better crystallinity. After aging, the precipitate is washed with water if necessary, and the precipitate is collected by means such as filtration and dried. The drying temperature should not be too high, preferably at about 200-300 ° C, more preferably at 220-250 ° C for about 1-20 hours, especially about 5-1
It is preferably performed for 5 hours.

The element-holding zinc oxide powder can be used as it is as a component of the external preparation for skin, but if necessary, a surface-treated one by a known method can be used. As the surface treatment, methyl hydrogen methylpolysiloxane, trimethylsiloxysilicic acid, silicone treatment such as methylpolysiloxane, fluorine treatment with perfluoroalkyl phosphate, perfluoro alcohol, etc., amino acid treatment with N-acyl glutamic acid, etc.,
Lecithin treatment, metal soap treatment, fatty acid treatment, alkyl phosphate ester treatment and the like can be mentioned.

The element-holding zinc oxide powder may be used alone or in combination with the element-holding zinc oxide powder in an average particle diameter of 10 to 300.
A composite with other powders can be used together with the fine particle titanium oxide of nm. In this case, other powders include nylon resin powder, polyethylene powder, polyester powder, silicone resin powder, polystyrene powder, epoxy resin powder and the like. As a method of compounding, element-holding zinc oxide powder or element-holding zinc oxide powder and fine particle titanium oxide having an average particle diameter of 10 to 300 nm and other powders, using various ball mills, ong mills, screen mills, hybridizers and the like A method of mixing can be applied. In addition, in the case of this compounding, bases such as cosmetics and external medicines can be mixed.

In the skin external preparation of the present invention, the amount of the element-holding zinc oxide powder varies depending on the kind of the skin external preparation and the like, but is preferably 0.1 to 50% by weight as the element-holding zinc oxide powder in the skin external preparation. And particularly preferably 0.5 to 30% by weight, more preferably 1 to 25% by weight.

The external preparation for skin of the present invention may further contain a water-soluble polyhydric alcohol in order to further enhance the moisturizing effect. Such a water-soluble polyhydric alcohol is not limited as long as it has two or more hydroxyl groups in a molecule. For example, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, dipropylene Glycol, glycerin or diglycerin, polyglycerin such as triglycerin and tetraglycerin, glucose, maltose, maltitol, sucrose, fructose, xylitol, sorbitol, maltotriose, threitol, erythritol, sugar alcohols and the like, These can be used alone or in combination of two or more. The content of these water-soluble polyhydric alcohols in the external preparation for skin is preferably 0.1 to 75% by weight, particularly 0.5 to 4% by weight.
0% by weight, more preferably 1 to 25% by weight.

The skin external preparation of the present invention may further contain an ultraviolet protection component such as an organic ultraviolet absorber or an inorganic ultraviolet scattering agent in order to further improve the ultraviolet protection effect.

Examples of the organic ultraviolet absorber include para-aminobenzoic acid (PABA), PABA monoglycerin ester, N, N-dipropoxy PABA ethyl ester,
Benzoic acid derivatives such as N, N-diethoxy PABA ethyl ester; anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; salicylic acid derivatives such as amyl salicylate, menthyl salicylate, homomenthyl salicylate; 2-ethylhexyl-p-methoxycinna Cinnamate derivatives such as mate, octyl cinnamate, ethyl-α-cyano-β-phenyl cinnamate;
4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-
Benzophenone derivatives such as 4-methoxybenzophenone-5-sulfonic acid; 3- (4′-methylbenzylidene)
Camphor derivatives such as -d, l-camphor; 4-methoxy-4'-t-butyldibenzoylmethane, 1-
UV absorbers such as (3,4-dimethoxyphenyl) -4,4'-dimethyl-1,3-pentadione; dietalamine-p-methoxycinnamate, 2-hydroxy-
Water-soluble ultraviolet absorbers such as sodium 4-methoxybenzophenone-5-sulfonate, tetrahydroxybenzophenone, sodium 3-hydroxy-4-methoxycinnamate and sodium ferulate can be used. These may be used alone or in combination of two or more. They can be used in combination. The compounding amount of the organic ultraviolet absorber is preferably 0.1 to 40% by weight in the external preparation for skin, particularly 0.5 to 2% by weight.
0% by weight is preferred.

As the inorganic ultraviolet scattering agent, titanium oxide,
Examples thereof include iron oxide, zinc oxide, talc, mica, barium sulfate, alumina, silica, and the like. Of these, titanium oxide is preferable. These can be used alone or in combination of two or more. The titanium oxide preferably has a particle size of 0.1 to 100 nm, and may be used as it is or after a surface treatment similar to that of the element-holding zinc oxide powder. The compounding amount of the inorganic ultraviolet scattering agent is 0.01 to 2 in the external preparation for skin.
0% by weight is preferable, and particularly preferably 0.05 to 10% by weight.

Of these, organic UV absorbers are particularly preferred from the viewpoint of high UV protection effect and feeling of use of external preparations. When an organic ultraviolet absorber and an inorganic ultraviolet scattering agent are used in combination, it is preferable to add 1 to 40% by weight of the total amount in the skin external preparation as an ultraviolet protection component.

The external preparation for skin of the present invention may be blended with silicone oil or ether-modified silicone in order to enhance the durability and the durability of the ultraviolet protective effect. The silicone oil is not particularly limited as long as it is blended in ordinary cosmetics. For example, octamethylpolysiloxane, tetradecamethylpolysiloxane, methylpolysiloxane, highly polymerized methylpolysiloxane, methylphenylpolysiloxane In addition to siloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, etc., trimethylsiloxysilicic acid, the following general formulas (1) and (2);

[0028]

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(Wherein R ¹ and R ² each have 1 carbon atom)
And R ³ represents a linear, branched or cyclic alkyl group, alkenyl group or fluoroalkyl group having 1 to 40 carbon atoms, and R ⁴ represents a linear or branched chain having 7 to 40 carbon atoms. A chain or cyclic alkyl group, alkenyl group or fluoroalkyl group, e is a number of 2 or more, f is a number of 3 or more, and e + f = 5 to 6000) Organopolysiloxane and the like can be mentioned.

The amount of these silicone oils is preferably 2 to 80% by weight in the external preparation for skin, and more preferably 10 to 80% by weight.
60% by weight is preferred.

The ether-modified silicone is not particularly limited as long as it is a compound in which at least a part of the siloxane is substituted with a group having an ether bond, and examples thereof include the following.
More than one species can be used in combination.

The following general formula (3):

[0033]

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[Wherein R¹¹, R¹²And R¹³Less of
One of the following formulas: R¹⁴(OC_ThreeH₆)_b(OC_TwoH _Four)_aO (CH_Two)_p-(R
¹⁴Represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms,
a and b are average values, each of which represents a number from 0 to 35;
Represents a group of 1 to 5), and the remainder is methyl.
And m and n are average values, and m is 1 to 200
And n represents a number from 0 to 50].
Ter-modified silicone. Of these, the molecular weight is 2000
５０50,000¹¹~ R¹³Is occupied by molecular weight
Is preferably 5 to 40%. Furthermore, the general formula
In (3), m is 50 to 80, n is 0 to 2, and a is 9-1.
0, b is 0, p is 3, R¹⁴Is a hydrogen atom or m
90 to 110, n is 0, a is 11 to 13, b is 0, p
Is 3, R¹⁴Is preferably a hydrogen atom. like this
As an ether-modified silicone represented by the following formula (3):
Is a SH-3775 series manufactured by Dow Corning Toray
Commercially available products such as powders can also be used.

The following general formula (4):

[0036]

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Wherein R ²¹ represents a hydrocarbon group having 1 to 5 carbon atoms, R ²² represents a hydrocarbon group having 6 to 16 carbon atoms,
Represents an alkylene group, and R ²³ represents the following formula:-(OC ₂ H ₄ ) _q- (OC
_{^{3 H 6) r -OR 2 4}} (R 24 represents a hydrogen atom or a lower alkyl group, with q and r q ≦ r, and _{- (OC 2 H 4) q} - (OC 3 H 6) molecular weight of _r Represents a number that represents 600 to 3500), z represents a number of 1 to 3, and x and y represent x <3y
And x + y + z = 30 to 400. _{However, - (OC 2 H 4)} q - (OC 3 H 6) the total weight of _r 1 of the total weight of the polyether alkyl-modified silicone represented by formula (4)
/ 3 or less].

C 1-5 represented by R ²¹ in the formula (4)
Examples of the hydrocarbon group include an alkyl group or an alkenyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a butyl group, a pentyl group, or a vinyl group. Groups are preferred. The hydrocarbon group having a carbon number of 6 to 16 represented by R ^22, a hexyl group, heptyl group, octyl group, nonyl group,
Examples include linear alkyl groups such as decyl group, undecyl group, dodecyl group, tetradecyl group, and hexadecyl group, and branched-chain alkyl groups such as isooctyl group, s-octyl group, and 2-ethylhexyl group. Of these, dodecyl group Is preferred. When y> 1, R ²² may be the same or arbitrarily different for each repeating unit. Examples of the alkylene group represented by Q in the formula (4) include a methylene group, an ethylene group, a propylene group, a trimethylene group, and a tetramethylene group. Among them, a propylene group and a trimethylene group are preferable.
In the formula (4), R ²⁴ in the group representing R ²³ represents a hydrogen atom or a lower alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group). preferable. Also, q and r are q
= 15 and r = 0, q = r = 25 or q = 29 and r = 7 is preferred. In the formula (4), x is preferably from 0 to 100, particularly preferably 0, and y is preferably a number such that y + z = 30 to 70, and z
Is preferably 2 or more.

As the polyether / alkyl-modified silicone represented by the formula (4), “DC Q2-2” sold by Dow Corning Toray Silicone Co., Ltd.
500 "(lauryl methicone copolyol; in formula (4), R ²¹ is a methyl group, R ²² is a dodecyl group, x = 0), and the like.

The following general formula (5):

[0041]

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[Wherein R³¹, R³², R³³And R³⁴Out of
At least one of the following formula (6): -A-OCH_Two CH (O
R⁴¹) CH_Two OR⁴²(Where A is 2 to 3 carbon atoms)
A divalent hydrocarbon group;⁴¹And R⁴²Are hydrogen sources
And a hydrocarbon group having 1 to 5 carbon atoms. Where R⁴¹
And R⁴²One of them represents a hydrogen atom)
Represents a group, and the balance is a straight or branched chain having 1 to 30 carbon atoms.
Is a cyclic hydrocarbon group or the following formula: -BR⁴³(Where B is
Divalent carbonization containing ether bond and / or ester bond
Represents a hydrogen group;⁴³Is a straight or branched chain having 1 to 30 carbon atoms
Or a cyclic hydrocarbon group).
s, t and u each represent a number from 0 to 200, and s + t
R when + u = 0³¹One or more of the above is represented by the above formula (6).
(Where R is³¹One of which is in equation (6)
A is a trimethylene group and R⁴¹And R ⁴²Is a hydrogen atom
And the remaining R³¹, R³², R³³And R³⁴Is all
Alkyl glyceryl represented by
Ruether-modified silicone.

In the above formula (5), the compound having 3 to 3 carbon atoms represented by A
The divalent hydrocarbon group of 20 includes a trimethylene group,
Tramethylene group, pentamethylene group, hexamethylene
Group, heptamethylene group, octamethylene group, nonametyl
Group, decamethylene group, undecamethylene group, dodecamene
Tylene group, tetradecamethylene group, hexadecamethylene
Linear alkylene group such as octadecamethylene group,
Pyrene group, 2-methyltrimethylene group, 2-methyltet
Ramethylene group, 2-methylpentamethylene group, 3-pen
Examples include a branched chain alkylene group such as a tamethylene group.
Wear. R⁴¹And R ⁴²A hydrocarbon having 1 to 5 carbon atoms represented by
As the group, methyl group, ethyl group, propyl group, butyl
Group, pentyl group, isopropyl group, s-butyl group, t-
Butyl, neopentyl, cyclopentyl, etc.
Chain, branched or cyclic alkyl groups.
Wear. Further, an ether bond represented by B and / or
As the divalent hydrocarbon group containing a ter bond, the following formula:-(CH
_Two)_h-(OC_TwoH_Four)_i-(OC_ThreeH₆)_j-O-,-(CH_Two)_h-O-CO-,-(CH_Two)_h-C
OO- (in these, h represents an integer of 3 to 20, i
And j represent a number from 0 to 50).
be able to. Also, R ⁴³Having 1 to 30 carbon atoms
Linear, branched or cyclic hydrocarbon groups include methyl
Group, ethyl group, isopropyl group, butyl group, pentyl
Group, hexyl group, heptyl group, octyl group, nonyl group,
Decyl, undecyl, dodecyl, tetradecyl
Group, hexadecyl group, octadecyl group, eicosyl group,
Doeicosyl group, tetraeicosyl group, hexaeicosyl
Linear groups such as octyl, octa eicosyl, and triaconsyl groups
Alkyl group, isopropyl group, s-butyl group, t-butyl
Group, neopentyl group, 1-ethylpropyl group, 1-f
Branched alkyl groups such as butyldecyl group, cyclopentyl
Group, cyclohexyl group, abiethyl group, cholesteryl group
And the like. like this
An alkyl glyceryl ether-modified resin represented by the formula (5)
The cone is manufactured by the method described in Japanese Patent Application Laid-Open No. 5-112424.
Can be manufactured.

The amount of the ether-modified silicone is preferably 0.05 to 20% by weight, more preferably 1 to 10% by weight, in the external preparation for skin.

The external preparation for skin of the present invention may contain other components in addition to the above components within a qualitative and quantitative range which does not impair the object of the present invention. Such other components include, for example, hydrocarbons such as solid or liquid paraffin, crystal oil, ceresin, ozokerite or montan wax; vegetable oils or animal fats and waxes such as olive, carnauba wax, lanolin, squalane, squalene;
Examples thereof include stearic acid, palmitic acid, oleic acid, glycerin monostearate, glycerin distearate, glycerin monooleate, isopropylstearate, and neopentyl glycol dicaprate. Also, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene hydrogenated castor oil alkyl sulfate, polyoxyalkyl sulfate, alkyl phosphate, Surfactants such as oxyethylene alkyl phosphates, fatty acid alkali metal salts, sorbitan fatty acid esters, glycerin fatty acid esters, alkyl glyceryl ethers; mica, talc, sericite,
Powders of extenders such as kaolin, nylon powder, polymethylsilsesquioxane and the like, and powders of organic pigments and the like, which are surface-treated in the same manner as described above; ethanol, isopropyl alcohol, cetyl alcohol, stearyl alcohol, palmityl alcohol , Alcohols such as hexyldecyl alcohol; inorganic salts such as magnesium sulfate, calcium sulfate, sodium sulfate, magnesium chloride, and sodium chloride; viscosity modifiers such as polyvinyl alcohol, carboxyvinyl polymer, carboxymethylcellulose, gelatin, tracant gum, xanthan gum; And the like, preservatives, pH adjusters, wetting agents, dyes and the like.

The dosage form of the external preparation for skin of the present invention is not particularly limited, and can be a skin cosmetic such as cream, emulsion, lotion, foundation, lipstick, aerosol cosmetic and the like.

[0047]

The skin cosmetic of the present invention is excellent in ultraviolet ray protective effect and transparency, and also excellent in persistence of these effects. In addition, there is no whitening after application, and the moisture retention and the feeling of use are excellent. Furthermore, it does not cause aggregation and has excellent dispersibility.

[0048]

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. The average particle size, average particle thickness, and average plate ratio in the following synthesis examples, as well as the content of additional elements, ultraviolet light absorption, and transparency in the visible part were measured by the following methods.

(1) Average Particle Size, Average Particle Thickness, and Average Plate Ratio The average particle size is obtained by measuring the average of the particle sizes of 20 arbitrary particles in an arbitrary field of view in a transmission electron micrograph. Was repeatedly determined. The average particle thickness was determined by reading the thickness in the same field of view of a transmission electron micrograph and calculating the arithmetic average of the thickness of all readable particles. Table 1
The display of the average grain thickness is omitted. The average plate-like ratio was determined by the average particle diameter / average particle thickness, and the value was rounded off to the nearest whole number.

(2) Additive element content A certain amount of dry powder was dissolved in 6N hydrochloric acid, and a solution obtained by diluting the solution to a certain volume was subjected to ICP emission analysis to determine the zinc concentration and other additive element concentrations. Further, the molar ratio of the additive element to zinc was determined.

(3) UV-absorbing property and transparency Glycerin / water = 9 so that the powder becomes 0.03% by weight.
/ 1 (weight ratio), the dispersion was placed in a cell having an optical path length of 1 mm, and the transmission spectrum at 190 nm to 700 nm was measured using a spectrophotometer. The ultraviolet absorptivity was evaluated at a light transmittance of 363 nm, and the transparency was evaluated at a light transmittance of 500 nm. Here, the smaller the value of the light transmittance at 363 nm, the higher the ultraviolet absorbing power, and the larger the value of the light transmittance at 500 nm, the higher the transparency.

The following five types of ether-modified silicones were used. (A) Ether-modified silicone A: a dimethylsiloxane / methyl (polyoxyethylene) siloxane copolymer represented by the formula (3). However, R ¹¹ = R ¹² = methyl group, R
_{^{13 = H (OC 3 H 6}} ) b (OC 2 H 4) a O (CH 2) p (a = 7~15, b =
0, p = 3), m = 50-100, n = 1-5. (B) Ether-modified silicone B: dimethylsiloxane / methyl (polyoxyethylene) siloxane copolymer represented by the formula (3). However, R ¹¹ = R ¹² = methyl group, R
_{^{13 = H (OC 3 H 6}} ) b (OC 2 H 4) a O (CH 2) p (a = 2~5, b = 0,
p = 3), m = 20-30, n = 2-5.

(C) Ether-modified silicone C: Formula
Dimethylsiloxane methyl (poly) represented by (3)
(Xylene) siloxane copolymer. Where R¹¹= R
¹²= Methyl group, R¹³= C_FourH₉(OC_ThreeH₆)_b(OC_TwoH_Four)_aO (CH_Two)
_p(A = 0, b = 7 to 13, p = 3), m = 4 to 10,
n = 1-6. (D) Ether-modified silicone D: represented by the formula (4)
Lauryl methicone copolyol. Where R^{twenty one}= Methyl
Group, R^{twenty two}= Dodecyl group, R^{twenty three}=-(OC_TwoH_Four)_q-(OC_ThreeH₆)_r-OH
(Q = 10-30, r = 10-30), Q = trimethyle
Group, x = 0, y = 30-70, z = 1-6. (E) Ether-modified silicone E: represented by the formula (5)
Alkyl glyceryl ether-modified silicone. However,
R ³⁴One of them is -A-OCH_TwoCH (OR⁴¹) CH_TwoOR⁴²(A = C₁₁H_{twenty three},
R⁴¹= R⁴²= H), s + t = 60, u = 40.

Synthesis Example 1 Zinc sulfate 1.6 × 10 ^-1 mol, sodium sulfate 3.8 ×
^10-2 mol and ferrous sulfate 1.6 × as a salt of the additional element
10 ⁻⁵ mol was dissolved in 315 ml of 5 × 10 ⁻² mol aqueous sulfuric acid. Next, this solution was mixed with a homomixer to 6000.
2N sodium hydroxide aqueous solution 2 while stirring at rpm
30 ml was charged in 15 seconds (pH = 12.8), and after a precipitate was formed, stirring was continued for 10 minutes. Then 10
Aged at 0 ° C for 90 minutes, filtered, washed with water,
After drying for 0 hour, an element-holding zinc oxide powder was obtained. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 2 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^except that the amount of ferrous sulfate added was changed to 8 × 10 ⁻⁵ mol. Observing the powder thus obtained with a scanning electron microscope,
It was confirmed that the particles were flaky particles. About this powder,
The measurements (1) to (3) were performed. Table 1 shows the results.

Synthesis Example 3 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^except that the amount of ferrous sulfate added was 1.6 × 10 ⁻⁴ mol.
The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 4 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^except that the amount of ferrous sulfate added was 1.6 × 10 ⁻³ mol.
The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 5 1.6 × zirconium oxychloride was used instead of ferrous sulfate.
An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^{except that 10-5} mol was used. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 6 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 except that 8 × 10 ^-5 mol of zirconium oxychloride was used instead of 1.6 × 10 ^-5 mol of ferrous sulfate. Was. The powder thus obtained was observed with a scanning electron microscope and confirmed to be flaky particles (see FIG. 1). This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 7 Ferrous sulfate 1.6 × 10^-FiveJil oxychloride instead of mole
Conium 1.6 × 10 ^-FourSynthesis Example 1 was used except that a mole was used.
Similarly, element-holding zinc oxide powder was obtained. in this way
Observe the powder obtained by scanning electron microscope
The particles were confirmed to be particles. About this powder,
(1) to (3) were measured. Table 1 shows the results.

Synthesis Example 8 Element-holding zinc oxide powder was prepared in the same manner as in Synthesis Example 1 except that 1.6 × 10 ⁻³ mol of zirconium oxychloride was used instead of 1.6 × 10 ⁻⁵ mol of ferrous sulfate. I got The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 9 1.6 × 10 ^-1 mol of zinc nitrate was used in place of zinc sulfate.
Element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^except that 1.6 × 10 ⁻⁵ mol of magnesium nitrate was used instead of ferrous sulfate. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 10 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 9 ^except that the amount of magnesium nitrate was changed to 1.6 × 10 ⁻⁴ mol. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 11 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 9 ^except that the amount of magnesium nitrate added was 1.6 × 10 ⁻³ mol. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 12 Calcium nitrate was replaced with 8 × 10 ^{−5 in place of} magnesium nitrate
An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 9 except that mol was used. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 13 An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 except that germanium chloride was used in an amount of 8 × 10 ⁻⁵ mol instead of 1.6 × 10 ⁻⁵ mol of ferrous sulfate. . The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. About this powder, said (1)-
The measurement of (3) was performed. Table 1 shows the results.

Synthesis Example 14 Manganese sulfate 8 was used in place of 1.6 × 10 ^-5 mol of ferrous sulfate.
An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 ^except that × 10 ⁻⁵ mol was used. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Synthesis Example 15 An element-bearing zinc oxide powder was obtained in the same manner as in Synthesis Example 1, except that 4 × 10 ^-5 mol of yttrium chloride was used instead of 1.6 × 10 ^-5 mol of ferrous sulfate. . The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. About this powder, said (1)-
The measurement of (3) was performed. Table 1 shows the results.

Synthesis Example 16 Synthesis Example 1 was repeated except that 1.6 × 10 ^-5 mol of ferrous sulfate was replaced by 8 × 10 ^-5 mol of zirconium oxychloride and 8 × 10 ^-6 mol of ferrous sulfate. Similarly, element-holding zinc oxide powder was obtained. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3).
Table 1 shows the results.

Synthesis Example 17 8 × 10 ^-5 mol of zirconium oxychloride and 8 × 10 ^-6 magnesium sulfate in place of 1.6 × 10 ^-5 mol of ferrous sulfate
An element-holding zinc oxide powder was obtained in the same manner as in Synthesis Example 1 except that mol was used. The powder thus obtained was observed with a scanning electron microscope to confirm that it was flaky particles. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.

Comparative Synthesis Example A flaky zinc oxide powder was obtained in the same manner as in Synthesis Example 1 except that no element having a valence of +2 or more was added. This powder was subjected to the above measurements (1) to (3). Table 1 shows the results.
A method of depositing or adhering a trace element to the flaky zinc oxide powder and diffusing it by a subsequent heat treatment was attempted, but a heat treatment exceeding at least 500 ° C. was required. As a result, the flaky zinc oxide collapsed or deformed. In addition, the flaky zinc oxide powder agglomerated during the heat treatment, and the trace elements could not be sufficiently diffused.

[0072]

[Table 1]

As is clear from Table 1, Synthesis Examples 1 to 17
The element-holding zinc oxide powder was excellent in both ultraviolet absorption and transparency as compared with the powder of Comparative Synthesis Example using only flaky zinc oxide. This result indicates that the element having a valence of +2 or more acts to promote the thinning of the particle form, and as a result, the particle thickness is reduced (that is, the plate ratio is increased). Is estimated to decrease.

Example 1 and Comparative Example 1 The components having the compositions shown in Table 2 were mixed to obtain an O / W type cream. With respect to these O / W type creams, the UV protection effect and the change in appearance (whiteness) after application were tested. The UV protection effect was evaluated by the UV protection index of a Hartley white guinea pig determined by the following formula. The change in appearance after application was measured by measuring the change in color (ΔE value) after application to the skin with a color difference meter. Table 2 shows the results.

[0075]

(Equation 1)

[0076]

[Table 2]

As is clear from Table 2, the cream of Example 1 had an excellent ultraviolet protection effect, and did not become white after application. Also, it was excellent in moisturizing property and feeling of use.

Example 2 and Comparative Example 2 The components having the compositions shown in Table 3 were mixed to obtain an O / W type cream. For these O / W creams, the UV protection effect and the change in appearance (whiteness) after application were tested in the same manner as in Example 1. Further, the moisturizing effect and the feeling upon use were tested by the following methods. Table 3 shows the results. (Moisturizing effect and feeling of use) When 20 O / W-type creams were used by 20 specialized panelists, the evaluation was made based on the number of persons having a moisturizing effect or the number of persons having a good feeling of use. ◎: 15 to 20 ○: 10 to less than 15 △: 5 to less than 10 ×: less than 5

[0079]

[Table 3]

As is clear from Table 3, the cream of Example 2 had an excellent ultraviolet protection effect, and did not cause whitening after application. Also, the moisturizing effect and the feeling of use were good.

Example 3 and Comparative Examples 3 and 4 The components having the compositions shown in Table 4 were mixed to obtain an O / W type cream. For these O / W creams, the UV protection index was measured in the same manner as in Example 1. Table 4 shows the results.

[0082]

[Table 4]

As is evident from Table 4, the cream of Example 3 was excellent in UV protection effect. Further, there was no whitening after application, and the feeling of use was good.

Example 4 A W / O-type cream having the following composition was produced, and the sustainability of the ultraviolet protection effect and the feeling of use were sensory evaluated by 20 specialized panelists. As a result, it was determined that the durability of the ultraviolet protection effect was good for 16 to 20 persons, and the feeling of use was 4 to 1
0 people were determined to be good.

(Composition) (% by weight) Element-holding zinc oxide of Synthesis Example 2 10.0 Squalane 10.0 Myristyl octyl dodecyl 15.0 α-monomethyl branched isostearyl glyceryl ether 1.0 Lipophilic glyceryl monostearate 1 0.0 Magnesium sulfate 0.5 Glycerin 5.0 Butylparaben 0.1 Methylparaben 0.1 Fragrance 0.1 Purified water Balance

Example 5 A W / O-type cream having the following composition was produced, and the sustainability of the ultraviolet protection effect and the feeling upon use were sensory evaluated by 20 specialized panelists. As a result, it was determined that 16 to 20 persons were good for both the durability of the ultraviolet protection effect and the feeling of use.

(Composition) (% by weight) Element-holding zinc oxide of Synthesis Example 2 10.0 Ether-modified silicone A (manufactured by Toray Dow Corning Co., Ltd., SH-3775C) 2.0 α-monomethyl branched isostearyl glyceryl ether 2.0 Methylpolysiloxane (6cSt) 5.0 Octamethyltetracyclosiloxane 20.0 Magnesium sulfate 0.5 Glycerin 5.0 Butylparaben 0.1 Methylparaben 0.1 Perfume 0.1 Purified water Balance

Example 6 A lotion having the following composition was produced by a conventional method. This lotion had an excellent UV protection effect and did not appear white after application. In addition, the moisturizing property and feeling of use were also good.

(Composition) (% by weight) Ethanol 30.0 Glycerin 5.0 Polyethylene glycol (1500) 3.0 Polyoxyethylene oleyl ether (20EO) 1.0 Polyoxyethylene hydrogenated castor oil (30EO) 0.7 Synthesis Element-holding zinc oxide of Example 2 5.0 Fragrance Trace amount Purified water Balance

Example 7 A W / O emulsion having the following composition was produced by a conventional method. This emulsion had an excellent ultraviolet protection effect, and did not appear white after application. In addition, the moisturizing property and feeling of use were also good.

(Composition) (% by weight) Silicon-coated element-holding zinc oxide of Synthesis Example 2 10.0 Polyether-modified silicone C (FZ-2110C, manufactured by Nippon Yunika) 1.5 Polyether-modified silicone B (Shin-Etsu Silicone) 1. KF-6015) 1.0 Polyether-modified silicone D (Toray Dow Corning, DC Q2-2500) 2.0 Methylpolysiloxane (6cSt) 20.0 Decamethylcyclopentasiloxane 20.0 Squalane 2. 0 Myristyl octyl dodecyl 1.0 Glycerin 3.0 Butylparaben 0.1 Methylparaben 0.1 Purified water Balance

Example 8 A W / O type cream having the following composition was produced by a conventional method. This cream had an excellent UV protection effect and did not whiten out after application. In addition, the moisturizing property and feeling of use were also good.

(Composition) (% by weight) Silicon-coated element-holding zinc oxide of Synthesis Example 3 10.0 Ether-modified silicone E 1.5 Polyether-modified silicone (KF-6015, manufactured by Shin-Etsu Silicone Co., Ltd.) 0.5 methyl poly Siloxane (6cSt) 5.0 Octamethyltetracyclosiloxane 20.0 Squalane 2.0 Myristyl octyl dodecyl 1.0 Dextrin fatty acid ester 0.5 Glycerin 3.5 Butylparaben 0.1 Methylparaben 0.1 Perfume 0.1 Purified water balance

Example 9 An O / W emulsion having the following composition was produced by a conventional method. This emulsion had an excellent ultraviolet protection effect, and did not appear white after application. In addition, the moisturizing property and feeling of use were also good.

(Composition) (% by weight) Silicon-coated element holding zinc oxide of Synthesis Example 6 10.0 Cetanol 1.0 Squalane 5.0 Olive oil 8.0 Jojoba oil 2.0 Polyoxyethylene hydrogenated castor oil (10EO) 1.0 Sorbitan monostearate 1.0 Ethanol 3.0 Glycerin 2.0 Butylparaben 0.1 Methylparaben 0.1 Purified water Balance

Example 10 An oily foundation having the following composition was produced by a conventional method. This oil-based foundation had an excellent ultraviolet protection effect, and did not appear white after application. In addition, the moisturizing property and feeling of use were also good.

(Composition) (% by weight) Silicon-coated element holding zinc oxide of Synthesis Example 9 20.0 myristyl octyl dodecyl 5.0 squalane 34.0 maocrocrystalline wax 6.0 kaolin 10.0 talc 10.0 coloring Pigment 15.0 Fragrance Trace

Example 11 An aerosol cosmetic having the following composition was produced by a conventional method. This aerosol cosmetic had an excellent ultraviolet protection effect, and did not appear white after application.

(Composition) (% by weight) Silicon-coated element-holding zinc oxide of Synthesis Example 12 20.0 Myristylisopropyl 2.0 Triclosan 0.01 Aluminum hydroxychloride 1.5 Talc 1.0 Fragrance 0.1 Propellant Balance

[Brief description of the drawings]

FIG. 1 is a micrograph showing the particle structure of an element-holding zinc oxide powder obtained in Synthesis Example 6.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Kinuda, Inventor 1130 Nishihama, Wakayama-shi, Wakayama (56) References JP-A-5-139930 (JP, A) JP-A-6-72821 (JP, A)

Claims (5)

(57) [Claims] 1. A flaky zinc oxide powder having an average particle diameter of 0.1 μm or more and less than 1 μm, an average particle thickness of 0.01 to 0.2 μm, and an average plate-like ratio of 3 or more, and an integral part of the flaky zinc oxide powder. Except for the zinc that has become
0.005 to 1.0 mole per 0 mole,
An external preparation for skin, comprising a powder having a light transmittance of at least 70% at 500 nm. 2. The external preparation for skin according to claim 1, wherein the element having a valence of +2 or more is at least one selected from the group consisting of iron, zirconium, calcium, germanium, manganese, magnesium and yttrium. 3. The external preparation for skin according to claim 1, further comprising a water-soluble polyhydric alcohol. 4. The external preparation for skin according to claim 1, further comprising an ultraviolet protection component. 5. The skin external preparation according to claim 1, further comprising a silicone oil and / or an ether-modified silicone.