JP6143640B2 - Acicular zinc oxide particles, production method thereof, and cosmetics - Google Patents

Description

  The present invention relates to acicular zinc oxide particles suitable for use as, for example, a cosmetic composition, a method for producing the same, and a cosmetic.

  In recent years, zinc oxide particles have been used, for example, as an ultraviolet shielding agent or to provide covering power in makeup cosmetics such as sunscreens, foundations, eye shadows, and lipsticks. Needle-like particles are used for the purpose of improving the effect of hiding wrinkles when applied to the skin. In addition, the said zinc oxide particle is used also for industrial uses, such as a filler, and is mix | blended for the purpose of provision of rigidity, the provision of a damping effect, etc.

  Zinc oxide particles used in these cosmetics and fillers are those having a uniform particle shape and particle diameter, those provided with a high wrinkle concealing effect due to their needle-like shape, and further have a high ultraviolet shielding effect. What you have is required.

  However, it is difficult to control the particle diameter of the zinc oxide particles currently used, most of them have a wide particle size distribution, and the form is not uniform. In addition, there is a problem that not a monodispersed state but an aggregate in which a plurality of particles overlap each other is formed, and the characteristics of zinc oxide cannot be sufficiently exhibited.

  In addition, zinc oxide is used as a UV-A shielding agent due to the band gap of zinc oxide, particularly among UV-A and UV-B, which are ultraviolet rays that reach the ground and are directly exposed to humans. However, although it has an effect as a UV-A shielding agent, it is poor in concealing effect such as wrinkles, and when blended in a foundation or the like, it needs to be used together with other materials having concealing effect.

  Zinc oxide is known to have photocatalytic activity. Zinc oxide can absorb the ultraviolet rays in sunlight and remove the direct influence of the ultraviolet rays in sunlight on the skin, while active oxygen free from a large amount of free electrons and holes. There are concerns about various adverse effects on the skin, ie phototoxicity, due to radicals. Therefore, surface protection and surface treatment of photocatalytically active particles, and the incorporation of radical trapping agents have been proposed as a protection method against phototoxicity caused mainly by active oxygen and free radicals in photocatalytically active powders. There is no need for zinc oxide particles having low photocatalytic activity.

By the way, various methods are known about the manufacturing method of zinc oxide. In general, a production method called French method is known as a dry method, and a production method called German method is known as a wet method.
In the French method, molten metal zinc is heated to about 1000 ° C. in a retort, the generated zinc vapor is oxidized with air, sent to an air cooling tube with a blower, cooled, and separated with a cyclone and a bag filter. It is a method of collecting.
The German method is a method in which a white basic zinc carbonate precipitate formed by adding a soda ash solution to an aqueous solution of zinc sulfate or zinc chloride is washed with water, dried, and calcined.

  However, the zinc oxide produced by these methods has a problem that the particle size is not uniform. In addition, since treatment at a high temperature is required, there are problems in that the environment is affected and the cost of the reaction apparatus is increased.

The acicular zinc oxide particles are conventionally produced by using a dry method (see, for example, Patent Document 1). However, as described above, in the dry method, zinc oxide has a problem that the particle size is non-uniform, and because it requires treatment at a high temperature, it has an impact on the environment and the cost of the reactor is high. There is a problem of becoming.
As an alternative to the dry method, a method of obtaining acicular zinc oxide particles by dissolving a water-soluble zinc salt with urea and subjecting it to heat treatment (for example, see Patent Document 2) has been proposed. The form cannot be controlled uniformly. Furthermore, the concentration at the time of synthesis is less than 0.01 mol / liter, so the yield is very low and the production efficiency is low.

Japanese Patent Laid-Open No. 56-120518 JP 2002-274847 A

  The present invention has been made in view of the above-mentioned problems, and acicular zinc oxide particles excellent in ultraviolet shielding property and wrinkle concealing effect, and an environmentally-friendly and simple and low-cost method to form the particle form. It is an object to provide a method for producing acicular zinc oxide particles that can be needle-shaped and whose particle diameter can be controlled, and a cosmetic that has a high ultraviolet shielding effect and is excellent in transparency and wrinkle concealing effect. To do.

In order to achieve the above object, the present inventors have intensively studied. As a result, a zinc compound solution obtained by re-dissolving zinc oxide with a strong acid such as nitric acid is heated to 40 ° C. or more, and an amine compound is added to the solution for 10 minutes or more. The inventors have found a method for producing acicular zinc oxide particles that can be controlled to have a needle shape by dripping while being hung and can also make the particle diameter uniform. Further, needle-like zinc oxide particles doped with a metal oxide can be obtained by adding a metal salt of a metal ion having a charge of +4 or less to the zinc compound solution and reacting under the above reaction conditions.
The acicular zinc oxide particles obtained by the above production method may be calcined at 300 ° C. to 1500 ° C. By performing this calcining treatment, the crystallinity of zinc oxide is improved, and the catalytic activity, etc. Can be controlled.
Furthermore, the needle-shaped zinc oxide particles obtained can be obtained by subjecting the obtained needle-shaped zinc oxide particles to a surface coating treatment with a compound such as polysiloxane, an alkylalkoxysilane compound, an alkyl titanate compound, or a fluorine compound. In addition, it has been found that by blending the needle-shaped zinc oxide particles into the cosmetic, it is possible to provide a cosmetic excellent in ultraviolet shielding effect, transparency, wrinkle concealing effect and feeling of use, and the present invention. It came to complete.

  In short, the acicular zinc oxide particles according to the first invention have an average major axis of 10 μm or less, an average minor axis of 1.0 μm or less, an aspect ratio of 4 or more, and 20% by mass dispersed in dimethylpolysiloxane. The diffuse transmittance when a sample having a thickness of 0.025 mm is measured with a haze meter is 40% or more.

Next, the acicular zinc oxide particles according to the second invention are characterized in that the acicular zinc oxide particles according to the first invention are doped with metal ions having a charge of +4 or less.
Here, the dope means that a metal oxide is added to the acicular zinc oxide particles in some form, and the addition state does not matter, and a part of the metal oxide enters the acicular zinc oxide particles. The dope concept encompasses both the state of being exposed and the state of acicular zinc oxide particles coated with a metal oxide.

  Next, in the method for producing acicular zinc oxide particles according to the third invention, a water-soluble zinc compound obtained by re-dissolving zinc oxide with an acidic solution is heated to 40 ° C. or more, and an amine compound is dropped into the solution in 10 minutes or more. It is characterized by combining.

  Next, the cosmetic according to the fourth invention is characterized by containing the acicular zinc oxide particles according to the first invention or the second invention.

  According to the acicular zinc oxide particles of the first invention, the average major axis is 10 μm or less, the average minor axis is 1.0 μm or less, the aspect ratio is 4 or more, and 20% by mass is dispersed in dimethylpolysiloxane, Since the diffuse transmittance when a sample having a film thickness of 0.025 mm is measured with a haze meter is 40% or more, in addition to the high UV shielding performance inherent in zinc oxide particles, high wrinkle concealment due to its shape The effect is imparted, and there is an effect of being excellent in ultraviolet shielding property, transparency, and wrinkle hiding effect. In addition, by baking the obtained acicular zinc oxide particle at 300-1500 degreeC, while being able to improve crystallinity, photocatalytic activity can be controlled.

  According to the second invention, since the needle-like zinc oxide particles are doped with metal ions having a charge of +4 or less, the particle size and photocatalytic activity can be suppressed.

  By adopting the method for producing acicular zinc oxide particles according to the third aspect of the invention, acicular zinc oxide particles having a uniform form and particle size can be produced, and the method is environmentally friendly, simple and low-cost. Acicular zinc oxide particles can be obtained.

  According to the cosmetic of the fourth invention, since the needle-like zinc oxide particles according to the first or second invention are blended, it is possible to obtain a cosmetic that has a high ultraviolet shielding effect and excellent transparency and wrinkle concealing effect. it can.

2 is an electron micrograph of multi-needle zinc oxide particles obtained in Production Example 1. FIG.

  Next, specific embodiments of acicular zinc oxide particles, a method for producing the same, and a cosmetic according to the present invention will be described below.

  The acicular zinc oxide particles of the present invention have an average major axis of 10 μm or less and an average minor axis of 1.0 μm or less, the aspect ratio of which can be controlled to 4 or more, and the size of the particle diameter can be controlled depending on reaction conditions. Can be controlled. Moreover, the average particle diameter of the needle-like zinc oxide particles of the present invention is measured by observing with a scanning electron microscope (SEM), measuring the diameter of any 20 particles, and calculating the average value. be able to. In addition, when the sample dispersed in 20% by mass with dimethylpolysiloxane and prepared to a film thickness of 0.025 mm using an applicator was measured with a haze meter, the diffuse transmittance was 40% or more, It is a powder with a high wrinkle concealing effect.

The acicular zinc oxide particles of the present invention are produced as follows. That is, it can be synthesized by heating a water-soluble zinc compound in which zinc oxide is redissolved with an acidic solution to 40 ° C. or more and dropping the amine compound into the solution in 10 minutes or more. The concentration of the zinc salt solution redissolved by the acidic solution is 0.01 to 0.5 mol / liter, and the concentration of the amine compound as a precipitant is also in the range of 0.01 to 0.5 mol / liter. Prepare as follows. The obtained precipitate is washed with water, filtered, dried, and pulverized to obtain acicular zinc oxide particles. In addition, you may stir during a heating reaction.
In addition, when doping a metal oxide, the metal salt to be doped is mixed in a zinc salt solution, and then precipitated by dropping the amine compound solution over 10 minutes at a temperature of 40 ° C. or higher. A thing is obtained. Acicular particles can be obtained by washing the resulting precipitate with water, filtering, drying and grinding. In addition, you may stir during a heating reaction.

Nitric acid, sulfuric acid, acetic acid, hydrochloric acid and the like can be used as the acidic solution for dissolving the zinc oxide.
Examples of the amine compound include ammonia, ethylamine, ethanolamine, diethylamine, diethanolamine, triethylamine, triethanolamine, hexamethylenetetramine, and the like. Of these, hexamethylenetetramine is particularly preferred.
In addition, as metal salts of metal ions having a valence of +4 or less when doped with metal oxide, iron nitrate, zirconium nitrate, magnesium nitrate, cobalt nitrate, nickel nitrate, aluminum nitrate, calcium nitrate, copper nitrate, chromium nitrate , Manganese nitrate, calcium chloride, silver chloride, chromium chloride, cobalt chloride, tin chloride, iron chloride, copper chloride, nickel chloride, magnesium chloride, aluminum sulfate, calcium sulfate, silver sulfate, tin sulfate, iron sulfate, copper sulfate, sulfuric acid Although nickel, magnesium sulfate, manganese sulfate, etc. are mentioned, it will not specifically limit as long as the conditions of supplementing a free electron and a hole are satisfied by dope of the metal oxide synthesize | combined from these.

  The ratio of the metal oxide doped into the acicular zinc oxide particles is preferably 0.05 to 10% by mass of the entire powder of acicular zinc oxide particles doped with the metal oxide. When the proportion of the metal oxide to be doped is less than 0.05% by mass, the effect of suppressing phototoxicity by the metal oxide cannot be exhibited. On the other hand, when it exceeds 10% by mass, the ultraviolet shielding effect is reduced. There's a problem.

  The reaction temperature is preferably 40 ° C. or higher, but the best condition is 80 ° C. or higher.

  As firing conditions when firing the acicular zinc oxide particles obtained by the above production method, it is preferable to carry out in a temperature range of 300 to 1500 ° C. More preferably, it is the range of 400-800 degreeC. As a result of analysis by X-ray diffraction even when the firing temperature is less than 300 ° C., the crystal structure of zinc oxide can be confirmed, but the orientation of the crystal is improved by firing at 400 ° C. or higher. As a result, defects such as oxygen defects in the crystal are reduced. Further, the ultraviolet ray shielding effect can also shield the ultraviolet ray from the longer wavelength side wavelength. On the other hand, when the temperature is higher than 1500 ° C., the treatment is performed at a high temperature, the load on the environment is increased, and the shape of the zinc oxide cannot be melted to maintain the needle shape.

  Next, in order to impart hydrophobicity and oleophobicity to the needle-like zinc oxide particles of the present invention, surface treatment may be performed with polysiloxane, an alkylsilane compound, an alkyl titanate compound, a fluorine compound, or the like. In addition to the above compounds, various conventionally known surface treatments can be applied. A plurality of these processes can be combined. The hydrophobic and oleophobic acicular zinc oxide particles (coated particles) will be described.

  In the present invention, when the needle-shaped zinc oxide particles are used as a foundation or sunscreen agent, after applying to the skin, water resistance and oil resistance are required. Therefore, the needle-shaped zinc oxide particles are hydrophobic or oleophobic. Must be granted. In order to impart hydrophobicity to the powder, the surface of the particles is coated with a compound such as polysiloxane, an alkylsilane compound, or an alkyl titanate compound. In order to impart hydrophobicity and oleophobicity to the particles, the surface of the particles is coated with a compound such as a fluorine compound.

Examples of the surface treatment include the following treatments.
a) Fluorine compound treatment: perfluoroalkyl phosphate treatment, perfluoroalkylsilane treatment, perfluoropolyether treatment, fluorosilicone treatment, fluorinated silicone resin treatment, etc. b) Silicone treatment: methyl hydrogen polysiloxane Treatment, dimethylpolysiloxane treatment, vapor phase tetramethyltetrahydrogencyclotetrasiloxane treatment, etc. c) pendant treatment: treatment to add alkyl chain after vapor phase silicone treatment d) silane coupling agent treatment e) titanium Treatment with coupling agent f) Treatment with aluminum coupling agent g) Treatment with oil agent h) Treatment with N-acylated lysine i) Treatment with polyacrylic acid j) Treatment with metal soap ... Treatment with stearate or myristate k) Acrylic Resin treatment l) Metal oxide Management m) polysaccharide processing n) naturally occurring component processing

  In addition, as a treatment method for coating the surface of a hydrophobic compound or an oleophobic compound, the particles to be coated are stirred in a suitable mixer, and the compound to be coated is added under a droplet or by spraying for a certain period of time. Stir vigorously at high speed. Then, the method of performing the reaction surface coating process by making it heat-ripen at 80-200 degreeC, continuing stirring is common. Alternatively, the surface coating compound is dissolved in alcohols such as ethanol, isopropyl alcohol and isobutanol, hydrocarbon organic solvents such as toluene, n-hexane and cyclohexane, polar organic solvents such as acetone, ethyl acetate and butyl acetate. In addition, after adding and stirring the cosmetic powder during stirring of this solution, the organic solvent is completely evaporated and removed, and then a method of performing surface coating treatment by heating and aging at 80 to 200 ° C. is also mentioned. It is done.

  As the mixing and dispersing method, an appropriate method can be selected according to the concentration and viscosity of the solution. Suitable examples include a method using a mixer such as a disper, a Henschel mixer, a Redige mixer, a kneader, a V-type mixer, a roll mill, a bead mill, or a biaxial kneader, or water and particles are sprayed into heated air. It is possible to select a spray drying method or the like that removes at a stroke. When pulverization is performed, a normal pulverizer such as a hammer mill, a ball mill, a sand mill, or a jet mill can be used. Since any of these pulverizers can obtain the same quality, it is not particularly limited.

  When performing said surface coating process, it is preferable that the mass ratio of the component which is a compound used for the surface coating process of particle | grains is 0.5-30 mass% with respect to the particle | grains which are coated. When the mass ratio is less than 0.5% by mass, the long lasting effect and the uniform adhesion to the skin are not sufficient, and when it exceeds 30% by mass, the feel becomes very oily and moisturized. Is not suitable.

  The form of the cosmetic compounding the surface-coated needle-shaped zinc oxide particles (coated needle-shaped zinc oxide particles) of the present invention is not particularly limited, but foundation, sunscreen, cosmetic liquid, lotion, lipstick, cosmetic cream , Facial cleanser, perfume, mouth freshener, mouth odor prevention agent, mouthwash, toothpaste, bath preparation, antiperspirant, soap, shampoo, rinse, body soap, body lotion, deodorant agent, hair cream agent, fair skin agent, skin cleanser And hair restorer.

  In addition, in cosmetics containing the acicular zinc oxide particles of the present invention, in addition to the powders, oils, powders (pigments, pigments, resins), fluorine compounds, resins, surfactants used in ordinary cosmetics Components such as an agent, a sticking agent, a preservative, a fragrance, a humectant, a physiologically active ingredient, a salt, a solvent, a chelating agent, a neutralizing agent, and a pH adjusting agent can be blended at the same time.

  Here, as the powder, for example, red 104, red 201, yellow 4, blue 1, black 401 and other dyes, yellow 4 aluminum lake, yellow 203 barium lake and other lake dyes, Nylon powder, silk powder, urethane powder, Teflon powder (Teflon: registered trademark), silicon powder, cellulose powder, polymers such as silicon elastomer, yellow iron oxide, red iron oxide, black iron oxide, chromium oxide, carbon black, ultramarine , Colored pigments such as bitumen, white pigments such as titanium oxide and cerium oxide, extender pigments such as talc, mica, sericite and kaolin, pearl pigments such as mica titanium, barium sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, Metal salts such as magnesium silicate, inorganic powders such as silica and boron nitride, Particles of titanium oxide, fine particles of iron oxide, alumina-treated fine titanium oxide particles, silica treated ultrafine titanium dioxide, bentonite, smectite, and the like. There are no particular restrictions on the shape and size of these powders. These powders may or may not be subjected to various conventionally known surface treatments. Examples of surface treatments include, for example, acrylic silicon treatment, methyl hydrogen polysiloxane treatment, silicone resin treatment, octyltriethoxysilane treatment, N-acylated lysine treatment, organic titanate treatment, silica treatment, alumina treatment, cellulose treatment, par Various hydrophilic, lipophilic, and water-repellent treatments such as fluoropolyether treatment and fluorinated silicone resin treatment can be used.

  Examples of the oil agent include higher alcohols such as cetyl alcohol, isostearyl alcohol, lauryl alcohol, hexadecyl alcohol, and octyldodecanol, fatty acids such as isostearic acid, undecylenic acid, and oleic acid, glycerin, sorbitol, ethylene glycol, and propylene. Polyols such as glycol and polyethylene glycol, myristic myristate, hexyl laurate, decyl oleate, isopropyl myristate, hexyl decyl dimethyloctanoate, glyceryl monostearate, diethyl phthalate, ethylene glycol monostearate, oxystearic acid Esters such as octyl, hydrocarbons such as liquid paraffin, petrolatum, squalane, lanolin, reduced lanolin, wax such as carnauba wax, Ink oil, cacao oil, coconut oil, balm kernel oil, camellia oil, sesame oil, castor oil, oils such as olive, ethylene-alpha-olefin co-oligomer, and the like. In addition, methyl hydrogen polysiloxane, dimethyl polysiloxane, methyl phenyl polysiloxane, polyether-modified organopolysiloxane, fluoroalkyl / polyoxyalkylene co-modified organopolysiloxane, alkyl-modified organopolysiloxane, fluorine-modified organopolysiloxane, amodimethicone , Silicon compounds such as amino-modified organopolysiloxane, silicon gel, acrylic silicon, trimethylsiloxysilicic acid, silicon RTV rubber, and fluorine compounds such as perfluoropolyether, fluorinated pitch, fluorocarbon, fluoroalcohol, and fluorinated silicone resin It is done.

  Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a betaine surfactant.

  Examples of the solvent include purified water, ethanol, light liquid isoparaffin, lower alcohol, ethers, LPG, fluorocarbon, N-methylpyrrolidone, fluoroalcohol, perfluoropolyether, alternative chlorofluorocarbon, and volatile silicon.

  Next, specific examples of acicular zinc oxide particles, a method for producing the same, and cosmetics according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the Example described below. Hereinafter, an example in which acicular zinc oxide particles are prepared is referred to as a “manufacturing example”, and an example in which a cosmetic is prepared using the acicular zinc oxide particles is simply referred to as an “example”.

(Preparation of 1 mol / liter zinc solution)
81.4 g of zinc oxide (fine zinc oxide: manufactured by Sakai Chemical) was weighed and dispersed in 500 ml of water. To the dispersion, 180 g of 69% nitric acid was gradually added with stirring to completely dissolve the zinc oxide. Thereafter, water was added to make up to 1000 ml, and a 1 mol / liter zinc solution was prepared.

(Production Example 1)
Water was added to 50 ml of the above 1 mol / liter zinc solution to make 500 ml and heated to 85 ° C. 500 ml of a 0.1 mol / liter hexamethylenetetralin solution was dropped into the solution at a flow rate of 8.3 ml / min, and the reaction was carried out for 3 hours. The precipitate was washed with water, filtered and dried to obtain acicular zinc oxide particles having an average major axis of 3 μm and an average minor axis of 0.5 μm. Then, it baked at 400 degreeC for 3 hours.
FIG. 1 shows a photograph of needle-like zinc oxide particles obtained in Production Example 1 observed with a scanning electron microscope.

(Production Example 2)
Water was added to 25 ml of the above 1 mol / liter zinc solution to 500 ml and heated to 85 ° C. A total amount of a 0.05 mol / liter hexamethylenetetralin solution (500 ml) was dropped into the solution at a flow rate of 8.3 ml / min, followed by reaction for 3 hours. The precipitate was washed with water, filtered and dried to obtain acicular zinc oxide particles having an average major axis of 4 μm and an average minor axis of 0.3 μm. Then, it baked at 400 degreeC for 2 hours.

(Production Example 3)
Water was added to 25 ml of the above 1 mol / liter zinc solution and dissolved in 500 ml. After 0.06 g of magnesium nitrate hexahydrate was completely dissolved in the zinc solution, the solution was heated to 85 ° C. A total amount of a 0.05 mol / liter hexamethylenetetralin solution (500 ml) was dropped into the solution at a flow rate of 8.3 ml / min, followed by reaction for 3 hours. The precipitate was washed with water, filtered and dried to obtain acicular zinc oxide particles doped with magnesium oxide having an average major axis of 3 μm and an average minor axis of 0.3 μm. Then, it baked at 400 degreeC for 2 hours.

(Production Example 4)
The acicular zinc oxide particles obtained in Production Example 1 were subjected to a surface coating treatment with methyl hydrogen polysiloxane. The surface coating treatment here is as follows.
That is, 1000 parts by mass of the powder of acicular zinc oxide particles obtained in Production Example 1 was put in a Henschel mixer, and then 20.4 parts by mass of methyl hydrogen polysiloxane was dissolved in 125 parts by mass of isopropyl alcohol. Were mixed well and mixed well with the multi-needle zinc oxide powder. Thereafter, the inside of the Henschel mixer was heated and decompressed to remove isopropyl alcohol. The treated powder was taken out from the Henschel mixer, pulverized and heat-treated to obtain coated multi-needle zinc oxide particles having a surface coating treatment of 2% by mass of the silicone compound.

  The acicular zinc oxide particles obtained in Production Examples 1 to 3 were mixed with dimethylpolysiloxane so as to be 20% by mass, and dispersed with a Hoovermarler at 100 rpm for 3 times. The dispersion was applied onto a quartz plate, a coating film having a film thickness of 0.025 mm was prepared using an applicator, and the diffuse transmittance was measured using a haze meter (HR-100, manufactured by Murakami Color Research Laboratory). .

  As is clear from the results shown in Table 1, the needle-like zinc oxide particles according to Production Examples 1 to 3 according to the present invention show a high diffuse transmission rate as compared with the comparative product (commercial product). . This proved to be excellent in transparency and wrinkle concealing effect.

The acicular zinc oxide of Production Example 3 and a comparative product were measured for photocatalytic activity. As a method for measuring the photocatalytic activity, a photooxidation test of nitric oxide was used. In other words, nitric oxide gas adjusted to a concentration of 1 ppm is passed through a container containing photocatalyst powder, and the photocatalyst powder is irradiated with light of 290 nm or more or 400 nm or more to generate active oxygen and free radicals. The photocatalytic activity was measured using the phenomenon that nitric oxide was decomposed into nitrate ions.
The test piece of photocatalyst powder was made into a flat plate of 20 mm × 15 mm, placed in a sealed container, and nitrogen monoxide gas having a concentration of 1 ppm was passed through the container containing the test piece at a flow rate of 200 ml / min. Thereafter, the concentration of nitric oxide gas when the test piece was irradiated with light of 290 nm or more and 400 nm or more was measured. The measurement results of photocatalytic activity are shown in Table 2.

  As can be seen from the results shown in Table 2, it can be seen that the acicular zinc oxide particles doped with the metal oxide have a high residual ratio of nitric oxide. This proved that the phototoxicity generated by light irradiation was suppressed.

Example 1
[Production of sunscreen]
A sunscreen was prepared according to the formulation shown in Table 3 and the following production method. In addition, the unit of the compounding quantity in a table | surface is the mass%.

<Manufacturing method>
Components A and B are mixed at 80 ° C., and after confirming that they are uniformly dispersed, they are cooled to 30 ° C. After cooling, component B was added little by little to component A while stirring with a homomixer, and mixed well until uniform to obtain a needle-shaped powder blended sunscreen.

(Comparative Example 1)
A product was obtained in the same manner as in Example 1 except that commercially available zinc oxide treated with silicone was used instead of the coated multi-needle zinc oxide produced in Production Example 4.

  About the cosmetics produced in Example 1 and Comparative Example 1, the sensory evaluation test regarding a usability | use_condition was implemented by 10 female panelists. The test was conducted in a questionnaire format, and each item was scored between 0 and 5 points, 0 points were badly evaluated, 5 points were evaluated as excellent, and the result was expressed as the average score of all panelists. . Therefore, it shows that evaluation is excellent, so that a score is high. The evaluation results are shown in Table 4.

  From the results shown in Table 4, it can be seen that Example 1 is superior to Comparative Example 1 in all of the wrinkle hiding effect, makeup retention, skin transparency, and elongation / spreadability.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the acicular zinc oxide particle which was excellent in the transparent feeling and wrinkle concealment effect which have formed the acicular shape, and dope an oxide to the acicular zinc oxide particle. Thus, it is possible to provide acicular zinc oxide particles with suppressed photocatalytic activity. In addition, by blending coated needle-like zinc oxide particles with a surface coated with a hydrophobic compound, it provides a cosmetic with excellent wrinkle concealment effect when applied to the skin, long-lasting skin, translucency of skin, and excellent elongation and spreadability. Is possible.

The acicular zinc oxide particles of the present invention are suitable for use as a makeup cosmetic composition or sunscreen cosmetic composition such as foundation, eye shadow, cheek red, lipstick, etc., and has great industrial applicability. is there.

Claims (4)

  A sample having an average major axis of 10 μm or less, an average minor axis of 1.0 μm or less, an aspect ratio of 4 or more, and a paste of 20% by mass dispersed in dimethylpolysiloxane having a thickness of 0.025 mm. Needle-like zinc oxide particles having a diffuse transmittance of 40% or more as measured by   The acicular zinc oxide particles according to claim 1, wherein the acicular zinc oxide particles are doped with a metal ion having a charge of +4 or less.   It is a manufacturing method of the acicular zinc oxide particle of Claim 1, Comprising: The water-soluble zinc compound which melt | dissolved zinc oxide with the acidic solution is heated at 40 degreeC or more, and an amine compound is dripped at the solution over 10 minutes or more. A method for producing acicular zinc oxide particles, characterized in that it is synthesized. A cosmetic comprising the acicular zinc oxide particles according to claim 1 or 2.