JP2000191490A - Ultrafine particulate zinc oxide silicone dispersion, its production and ultraviolet screening cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an ultrafine particulate zinc oxide silicone dispersion capable of manifesting high levels of dispersibility and dispersion stability and having both excellent visible light transmittance and excellent ultraviolet screening properties, to provide a method for producing the dispersion and further to obtain an ultraviolet screening cosmetic containing the dispersion as an active ingredient and having excellent performances. SOLUTION: This ultrafine particulate zinc oxide silicone dispersion comprises an ultrafine particulate zinc oxide powder having 0.001-0.2 μm average particle diameter, a dispersing agent and a silicone-based oil as a dispersion medium. The amounts of the ingredients are preferably 20-60 wt.% of the ultrafine particulate zinc oxide powder, 2-10 wt.% of the dispersing agent and 30-78 wt.% of the silicone based oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine zinc oxide / silicone dispersion and a method for producing the same, and an ultraviolet shielding cosmetic containing the dispersion as an ultraviolet shielding component.

[0002]

2. Description of the Related Art In recent years, not only ultraviolet B region but also ultraviolet A
There is increasing interest in UV protection in the field, and attention has been paid to ultrafine zinc oxide. Ultrafine zinc oxide has a higher visible light transmittance than titanium oxide, which has a strong hiding power, and also has an excellent ultraviolet shielding ability, in particular, an excellent shielding ability in the ultraviolet A region, and is highly safe. Used for fees. However, in general, ultrafine zinc oxide has a very small primary particle diameter of 0.1 μm or less, and tends to become coarse particles by secondary aggregation, so that it is difficult to sufficiently exhibit the original ultraviolet shielding ability and visible light transmittance. .

[0003] Therefore, when it is blended into cosmetics,
A large amount of dispersion energy is required to finely disperse the sub-aggregated oxide again. Also, in recent years, silicone oils having good usability and excellent water repellency and water resistance have been frequently used as a base for cosmetics. There is a strong demand for a dispersion in which zinc oxide is highly dispersed in a silicone oil.

Conventional methods for obtaining a dispersion containing zinc oxide fine particles include various types of media such as a bead mill, a ball mill, a paint shaker, a sand mill and other media media type dispersers, a colloid mill and a high-speed disperser such as a stirring type disperser. Dispersers have been used.

[0005] However, these media type dispersers and stirring type dispersers each have their advantages and disadvantages, and depending on their mechanism and type, 1) sufficient atomization cannot be performed, 2) media or lining or the like. Inevitability of impurities due to collision or friction with substances is inevitable, 3) deterioration due to heat generation, 4) loss of effective components, especially in volatile components, etc., 5) extremely high power cost and running. High, 6) Long time required for processing, especially when atomization is aimed at, processing efficiency per unit time is very low, 7) Continuous processing is difficult, 8) Detergency is poor, 9 ) It is difficult to handle due to work, 10) There is a high possibility of foreign matter being mixed because it can not be a closed system, 11) The installation location is limited because the device is large or heavy, etc. Question The it has.

[0006] When a silicone dispersion of ultrafine zinc oxide is obtained by using the above dispersing apparatus, the ultrafine zinc oxide is strongly agglomerated due to its high surface energy, and the primary particle diameter or primary particle diameter is high. It is not easy to produce a uniform fine particle dispersion dispersed to a particle diameter close to the diameter, and it is often a problem that zinc oxide particles cause inconvenient phenomena such as aggregation, sedimentation, aggregation, separation, and chalking. I have.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. The present invention provides an ultrafine zinc oxide / silicone dispersion which exhibits high dispersibility and dispersion stability without agglomeration when compounded in an agent, etc., and has both excellent visible light transmittance and ultraviolet shielding properties, and a method for producing the same. It is still another object of the present invention to provide a UV-shielding cosmetic having excellent performance, which contains the dispersion as an active ingredient.

[0008]

The ultrafine zinc oxide / silicone dispersion according to the present invention, which has solved the above problems, has an ultrafine zinc oxide powder having an average particle diameter of 0.001 to 0.2 μm. And a suspension containing a dispersant and a silicone-based oil as a dispersion medium.

In the above-mentioned dispersion of the present invention, the contents of the essential components are as follows: ultrafine zinc oxide: 20 to 60% by weight, dispersant: 2 to 10% by weight, and silicone oil: 30 to 78% by weight. % Is particularly preferable, and it is desirable that the surface of the ultrafine zinc oxide is subjected to a hydrophobic treatment with at least one selected from siloxanes and higher fatty acids.

Among the above essential components, dimethyl silicone oil is particularly preferable as the silicone oil.
It is at least one selected from the group consisting of cyclic dimethyl silicone oil, methylphenyl silicone oil, and trimethylsiloxysilicic acid, and particularly preferred as a dispersant is a polyether-modified silicone oil.

[0011] Further, according to the production method of the present invention, a suspension containing zinc oxide powder surface-treated with a hydrophobizing agent, a dispersant, and a silicone oil as a dispersion medium is subjected to a wet jet mill to obtain a suspension of 65 to 250 MPa. At a pressure of and / or at a flow rate of 180 to 350 m / sec, the suspensions collide with each other and / or with the wall surface, so that the zinc oxide powder is crushed into ultrafine particles and the presence of the dispersing agent is combined. Thus, it is characterized in that the ultrafine zinc oxide is uniformly finely dispersed in a dispersion medium.

In carrying out this method, the preferred contents of the above components are as follows: surface-treated zinc oxide powder: 20 to 60% by weight, dispersant: 2 to 10% by weight, and silicone oil: It is in the range of 30 to 78% by weight, and as the hydrophobizing agent, at least one selected from siloxanes and higher fatty acids is preferably used.

Among the silicone oils, particularly preferred are at least one selected from the group consisting of dimethyl silicone oil, cyclic dimethyl silicone oil, methylphenyl silicone oil and trimethylsiloxysilicic acid. The agent is a polyether-modified silicone oil.

The ultraviolet shielding cosmetic containing the above-mentioned ultrafine particulate zinc oxide / silicone dispersion as an active ingredient has excellent use in all of dispersion stability, ultraviolet shielding ability, visible light transmission, and touch. As an invention, it is included in the technical scope of the present invention.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the ultrafine zinc oxide / silicone dispersion according to the present invention has an average particle diameter of 0.1.
001-0.2 μm ultrafine zinc oxide powder, a surface treating agent for the zinc oxide powder, a siloxane-based dispersant,
And a suspension containing, as an essential component, a silicone oil as a dispersion medium. The effects of these components are as follows.

First, ultrafine zinc oxide powder is an essential component for providing ultraviolet shielding performance when used as a sunscreen cosmetic or the like, but at the same time, it has good transparency to visible light. It is necessary that the particles have an average particle diameter of 0.2 μm or less. On the other hand, when the average particle diameter exceeds 0.2 μm, it exhibits excellent shielding performance against ultraviolet rays, but has poor transparency to visible rays, and has a stable dispersion in a state of being dispersed in a silicone oil or the like. In addition, zinc oxide is easily separated and settled after standing for a short period of time, and the feel when practically used as a cosmetic or the like becomes poor.

On the other hand, the smaller the average particle diameter of the zinc oxide powder is, the higher the above-mentioned properties are.
It is extremely difficult to reduce the size to less than μm, even if a method as described later is employed, or the processing cost for atomization becomes extremely high and is not suitable for practical use.

In consideration of both practicality and performance, the more general ultrafine zinc oxide has an average particle diameter of 0.01 to 0.1.
The range is 1 μm. The zinc oxide itself may be manufactured by any method, but those manufactured by a French method, an American method, a wet method, or the like, having a small particle size and a relatively small particle size distribution. preferable.

The preferred content of the ultrafine zinc oxide is 20 to 20% by weight in the dispersion according to the present invention.
If it is less than 20% by weight, satisfactory absolute ultraviolet ray shielding performance cannot be obtained because the absolute amount is insufficient. On the other hand, if it exceeds 60% by weight, sufficient atomization cannot be performed. Due to the presence of the coarse particles, there arises a problem that it is difficult to sufficiently exhibit the original ultraviolet ray shielding ability and visible light transmittance. In consideration of such advantages and disadvantages, the lower limit of the more preferable content of the ultrafine zinc oxide is 40% by weight, and the more preferable upper limit is 55% by weight.

Next, the hydrophobizing agent for the zinc oxide powder is an indispensable component for acting on the surface of the ultrafine zinc oxide to enhance the affinity with the silicone oil.

In order to uniformly disperse ultrafine zinc oxide in silicone oil, the dispersibility can be increased to some extent by adding an appropriate amount of a dispersant to the dispersion. However, in order to uniformly disperse the ultrafine zinc oxide in the silicone oil in a finely dispersed state without adhering to each other and maintain a stable dispersion state, the surface of the ultrafine zinc oxide is made hydrophobic. It must be processed.

Incidentally, ultrafine zinc oxide which has not been subjected to hydrophobizing treatment has a poor affinity for silicone-based oil, so that the zinc oxide powders adhere to each other to form a large floc, resulting in poor dispersion stability. In addition, when used as cosmetics, etc., the skin feel becomes poor, and it cannot withstand market demands.

The hydrophobizing agent used here includes:
For example, siloxanes, higher fatty acids and the like can be mentioned, and these may be used alone or in combination of two or more as necessary.

In order to effectively exert the effect of the hydrophobizing agent, the hydrophobizing agent is contained in an amount of 0.5% by weight or more, more preferably 2% by weight or more, based on the zinc oxide in the form of ultrafine particles. Should. However, if the content is too high, some will not react with the powder surface, and the surplus hydrophobizing agent will remain in the dispersion or cosmetic and react with other components, accelerating the deterioration of other components. Therefore, it is desirable that the content be suppressed to preferably 10% by weight or less, more preferably 6% by weight or less.

In the present invention, the above-mentioned hydrophobizing treatment of the zinc oxide powder may be carried out by any method, but the most common one is a dry method, in which the zinc oxide powder is stirred with a mixer or the like. In this method, a hydrophobizing agent diluted with a suitable solvent is added and mixed to volatilize and remove the solvent, and then heat-treat as necessary.

Next, the dispersing agent is essential for uniformly dispersing the ultrafine zinc oxide finely in the silicone oil serving as a dispersion medium and ensuring excellent dispersion stability to withstand long-term storage. The type of the component is not particularly limited as long as it is a component that cannot be dispersed and has a function of promoting the dispersion of ultrafine zinc oxide in a silicone oil in a coexistence system with the hydrophobizing agent. And polyoxyethylene / methylpolysiloxane copolymers and poly (oxyethylene / oxypropylene) / methylpolysiloxane copolymers. These can be used alone or in combination of two or more if necessary. Can be.

In order to effectively exhibit the above-mentioned action of the dispersant, the content of the dispersant should be at least 2% by weight, more preferably at least 4% by weight, based on the total amount of the dispersion. Since a phenomenon in which aggregation of zinc oxide particles is rather induced by a dispersant appears, it is preferable that
% By weight, more preferably 15% by weight or less.

The silicone-based oil is a dispersion medium for the above-mentioned ultrafine zinc oxide, and has recently been widely used as a cosmetic base material having a good feeling in use and excellent water repellency and water resistance. Preferably, dimethyl silicone oil, cyclic dimethyl silicone oil,
Examples include methylphenylsilicone oil, trimethylsiloxysilicic acid and the like, and particularly preferred are octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane and the like. These silicone oils can be used alone or in combination of two or more in some cases.

The preferred content of the silicone oil as a dispersion medium cannot be determined uniformly because it varies depending on the dosage form of cosmetics and the like.
The dispersion is selected from the range of 78% by weight.
78% by weight, 40 to 65% by weight when blended in cream or paste UV shielding cosmetics, 3 when blended in foundation UV shielding cosmetics
It is selected from the range of 0 to 40% by weight.

The ultrafine zinc oxide / silicone dispersion of the present invention comprises the above-mentioned hydrophobized ultrafine zinc oxide, a suspension containing a dispersant and a silicone oil as essential components. However, in putting this into practical use as an ultraviolet shielding cosmetic, if necessary, higher alcohols, fatty acid esters, higher fatty acids,
Appropriate amounts of hydrocarbons, sterols, phospholipids, humectants, emulsifiers, pigments, colorants, fragrances, antioxidants, preservatives, organic ultraviolet absorbers, other inorganic powders, and the like can be added.

Next, a method for producing the above-described ultrafine zinc oxide / silicone dispersion will be described.

In the present invention, a suspension containing a hydrophobized zinc oxide powder and a silicone oil as a dispersing agent and a dispersing medium is subjected to a wet jet mill, and the suspension is subjected to 65-65.
250 MPa pressure and / or 180-350 m / se
At a flow rate of c, the suspensions collide with each other and / or against the walls, so that the zinc oxide powder has an average particle size of 0.1.
It is finely dispersed in a silicone-based oil via a dispersant while forming ultrafine particles in the range of 001 to 0.2 μm.

In this fine dispersion step, in order to efficiently and finely pulverize and finely disperse the zinc oxide in a short time without introducing foreign matter into the dispersion, a wet jet mill is used.
Pressure of 5 to 250 MPa and / or 180 to 350 m /
The suspension is treated at a flow rate of sec.

In the wet jet mill used here, the suspension to be treated is pumped at a high pressure to a nozzle arranged in a sealed state in a pressure vessel and a jet stream is formed in the nozzle to form a jet stream. The zinc oxide powder in the suspension is pulverized into ultrafine particles and finely dispersed in a silicone oil together with a dispersant.

Incidentally, a dry or wet jet mill has been conventionally known as a powder atomizer.
Of these, a dry jet mill is used to atomize particles by collision between particles of a substance to be treated or particles and a flow path wall in a gas phase flow, while a wet jet mill is used in a liquid phase flow. Particles are atomized by collision between particles of the substance to be treated or particles and the channel wall. In the case of a wet jet mill, cavitation and turbulence generated in the liquid phase in addition to the atomization by the collision -The compounding action such as shearing is also added, and the atomization of zinc oxide is remarkably promoted.

That is, the wet-type jet mill used in the present invention generates a high-pressure / high-speed flow by an arbitrary method, causes collision between liquids or a fluid and a flow path wall, and generates a turbulence generated by the high-pressure / high-speed flow. A device having a function of effectively utilizing flow, shear, and cavitation effects, and having a function of promoting the crushing and dispersion by atomizing a suspension to be treated.

As such a wet jet mill, there is a high-pressure homogenizer. Specifically, there is a method in which a suspension to be treated is jetted from a nozzle by a plunger pump or a rotary pump or the like to impinge on a fixed plate at a high speed. There is a method in which the suspensions to be processed collide with each other from the front. Then, when the suspension to be processed passes through the flow path at high speed or passes while colliding with the flow path wall, it is subjected to turbulence and shear,
The dispersoid (zinc oxide powder) contained in the suspension to be treated is finely pulverized, and when released under reduced pressure immediately after the collision, a cavitation effect occurs. , And are uniformly dispersed in the processing system while being pulverized into ultrafine particles.

As such a wet jet mill, a type utilizing high-speed injection by a valve plate commercially available as a "high-pressure homogenizer" (manufactured by APV Gaulin, Runny, Soavi, Nippon Seiki, etc.) A type in which a high-speed collision occurs in a slit-shaped flow path ("Microfluidizer" manufactured by Microfluidics Co., Ltd.), and a type in which a high-speed collision occurs in a single-character flow path that is communicated with a phase shift of 90 degrees ("" Nanomizer (manufactured by Nanomizer), a type that generates multiple collisions between fluids in the same nozzle ("Nanomaker"
Engineering Co., Ltd.), a type in which fluids collide with each other in a flat channel element (“Aqua” manufactured by Aquatech Co., Ltd.), or a type in which a jet is ejected from an opposing orifice into a room with an aspheric structure (“Ultimizer”). Sugino Machine Co., Ltd.)
As "Y", an ultra-high-speed / high-pressure wet-type jet mill and the like are commercially available.

Although these wet-type jet mills cause a slight difference in the pulverizing and dispersing effects of the zinc oxide powder depending on the characteristics of the device type, the dispersing devices such as the conventional media type dispersing machine as described above are used. Compared with the case of using, the atomization and fine dispersion can be advanced at a remarkably high efficiency, and an extremely stable ultrafine particle dispersion can be obtained.

At this time, in order to reduce the average particle diameter of the ultrafine zinc oxide finely dispersed in the silicone dispersion to 0.2 μm or less, the flow rate in the ultrahigh pressure / high speed processing section of the wet jet mill is set to 180 m / sec. As described above, it is necessary to secure the pressure more preferably to 200 m / sec or more and / or to secure the pressure to 65 MPa or more, more preferably 100 MPa or more. By the way, the flow velocity is 180m / se
When the pressure is less than c and / or the pressure is less than 65 MPa, the zinc oxide powder in the suspension is hardly pulverized to an average particle size of 0.2 μm or less, which is not the purpose of the present invention.

The effect of the fine pulverization and fine dispersion by the wet jet treatment is improved as the operation pressure and flow rate are increased. In some cases, the average particle diameter of the zinc oxide particles is reduced to 0.001 μm.
Although it is possible to reduce the size to ultra-miniaturized levels, if the pressure and flow rate are excessively increased, the pressure resistance and abrasion resistance of the equipment become extremely intense, which not only increases the equipment cost but also increases the cost of the nozzle. Is extremely short, and even if the average particle size of the zinc oxide particles is reduced to about 0.001 μm or less, the performance is not necessarily improved more than practical use. The upper limit of the pressure during the wet jet treatment is about 250 MPa or less, more generally 180M.
The pressure is about Pa or less, and the upper limit of the flow velocity is about 350 m / sec or less, and more generally about 300 m / sec or less.

The specific structure of the wet jet mill is not particularly limited as long as the above flow rate and / or pressure can be ensured, but it is preferable to achieve the object of the present invention.
For example, JP-A-9-201521 and JP-A-9-20152
No. 2 and the like, and among them, particularly preferable is a product name “Genus P
This is an ultra-high-speed and high-pressure wet jet mill commercially available as "Y". The use of this apparatus makes it possible to easily achieve the above-described ultra-high-speed and high-pressure processing conditions. Depending on the processing conditions, zinc oxide can be super-processed in a single pass and, if necessary, in two or more passes. It is possible to easily obtain a dispersion which is finely dispersed uniformly and stably.

When such a wet jet mill is used, the efficiency of crushing and dispersion is remarkably improved as compared with the case where dispersion processing is performed using a dispersing apparatus such as a conventional media type disperser. A very stable ultrafine zinc oxide / silicone dispersion can be obtained in a short time.

As described above, the ultrafine zinc oxide / silicone dispersion of the present invention has an average particle diameter of 0.001 to 0.001.
Extremely fine zinc oxide of 0.2 μm or less is uniformly emulsified and dispersed in silicone oil, and has high dispersibility and dispersion stability, and also has excellent visible light transmittance and ultraviolet shielding properties. Therefore, as will be specifically described later, this emulsified dispersion is used as an ultraviolet ray shielding component to form emulsion type, emulsion type, cream type, W / O type or O / W type foundation type, stick type, etc. Therefore, it can be widely used for various cosmetics such as sunscreen, makeup, and lipstick.

[0045]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited by the following examples. In the following, “%” means
Unless otherwise specified, it means "% by weight". The methods for measuring the average particle diameter and light transmission characteristics of the dispersions shown in the following examples are as follows.

(Average Particle Diameter of Dispersion) A sample was diluted about 3,000 times with silicone oil and measured using a laser diffraction particle size distribution analyzer.

(Light transmission characteristics) The sample was diluted with silicone oil and stirred with a homogenizer so that the concentration of ultrafine zinc oxide in the solution was 10%, and the diluted solution was coated on a quartz plate to a thickness of 5 μm. After coating, the transmittance at 700 to 250 nm was measured with a spectrophotometer.

Example 1 A surface treatment was carried out with a hydrophobizing agent (methylhydrogenpolysiloxane, 4% by weight based on zinc oxide particles) using Disper (trade name "TK. Robomix" manufactured by Tokushu Kika Kogyo Co., Ltd.). 45 parts by weight of zinc oxide particles having an average particle diameter of 2.18 μm (measured by laser diffraction), 7 parts by weight of a dispersant (polyoxyethylene / methylpolysiloxane copolymer), and a dispersion medium (decamethylcyclopentasiloxane) 48 parts by weight were uniformly mixed and suspended.

Next, this suspension was subjected to a pressure of 80 MPa (flow rate of 200 m / sec) and a pressure of 1 MPa using an ultra-high speed / high pressure wet jet mill “Genus PY” manufactured by Genus Corporation.
30MPa (flow rate 250m / sec) or pressure 200
One pass of pulverization / dispersion treatment was performed at MPa (flow rate: 320 m / sec) to obtain an ultrafine zinc oxide silicone dispersion.

Example 2 55 parts by weight of the same hydrophobicized zinc oxide powder as used in Example 1, 9 parts by weight of a dispersant (polyoxyethylene / methylpolysiloxane copolymer) and a dispersion medium (dimethyl 36 parts by weight of polysiloxane) were mixed and suspended with a disper (same as above), and the suspension was subjected to a pressure of 100 MPa (flow rate 22) using "Genus PY".
0m / sec), pressure 180MPa (flow rate 300m / s)
ec) or pressure of 220 MPa (flow rate of 330 m / sec)
One pass of pulverization and dispersion treatment was performed in c) to obtain an ultrafine zinc oxide silicone dispersion.

Example 3 Using a disper (trade name "TK. Robomix" manufactured by Tokushu Kika Kogyo Co., Ltd.), the surface was treated with a hydrophobizing agent (methyl hydrogen polysiloxane, 4% by weight based on zinc oxide particles). 45 parts by weight of zinc oxide particles having an average particle diameter of 1.36 μm (measured by laser diffraction), 7 parts by weight of a dispersant (polyoxyethylene / methylpolysiloxane copolymer), and a dispersion medium (decamethylcyclopentasiloxane) 48 parts by weight were uniformly mixed and suspended.

Next, this suspension was subjected to a pressure of 80 MPa (flow rate of 200 m / sec) and a pressure of 1 MPa using an ultra-high speed / high pressure wet jet mill “Genus PY” manufactured by Genus.
30MPa (flow rate 250m / sec) or pressure 200
One pass of pulverization / dispersion treatment was performed at MPa (flow rate: 320 m / sec) to obtain an ultrafine zinc oxide silicone dispersion.

Comparative Example 1 In Example 1, the pulverization using “Genus PY”
The dispersion treatment is performed at a pressure of 20 MPa (flow rate: 100 m / sec).
In the same manner as described above, a particulate zinc oxide silicone dispersion was obtained.

Comparative Example 2 In Example 2, the preparation of a silicone dispersion was attempted using zinc oxide powder that had not been hydrophobized.
When the zinc oxide powder was added to the mixture of the dispersion medium and the dispersant, the suspension lost its fluidity, and the pulverization / dispersion treatment using “Genus PY” was not possible. Therefore, the amount of the zinc oxide powder was reduced from 55 parts by weight to 30 parts by weight, and the amount of the dispersion medium was increased from 36 parts by weight to 61 parts by weight to prepare a suspension. And pressure 18
One pass of pulverization / dispersion treatment was performed at 0 MPa (flow rate 300 m / sec).

Comparative Example 3 The use of 45 parts by weight of the same hydrophobically treated zinc oxide powder as above was added to 55 parts by weight of decamethylcyclopentasiloxane as a dispersion medium without using a dispersant, and the mixture was uniformly dispersed by a disper. Tried to prepare a silicone dispersion,
The dispersibility of the zinc oxide powder in the dispersion medium was poor, and the fluidity of the suspension was extremely poor, and the pulverization and dispersion treatment by "Genus PY" could not be performed. Therefore, the mixing amount of the zinc oxide powder is set to 45.
Parts by weight to 33 parts by weight, and
A suspension was prepared by increasing the amount from 5 parts by weight to 67 parts by weight, and thereafter, the pressure was set to 180 MPa (flow rate 3
(00 m / sec), one pass of pulverization / dispersion treatment was performed.

The average particle diameter of zinc oxide in each of the silicone dispersions obtained above and the light transmittance of the dispersions are shown in Table 1.

[0057]

[Table 1]

From Table 1, the following can be considered.

Examples 1 to 3 satisfy all the requirements of the present invention. The transmittance at 550 nm in the visible light region is very high, while the transmittance at 300 nm in the ultraviolet region is very low. It can be seen that the film has good properties and excellent ultraviolet shielding performance.

On the other hand, in Comparative Example 1, the pressure and the flow rate by the wet jet treatment were insufficient, so that the zinc oxide powder was insufficiently formed into ultrafine particles, the transmittance in the visible light region was insufficient, and the ultraviolet shielding ability was sufficient. Not. In Comparative Example 2, zinc oxide powder not subjected to hydrophobization treatment was used. However, despite the use of a dispersant, the dispersibility of the dispersoid was poor, and the zinc oxide powder was not wet after wet jet treatment. Has caused secondary agglomeration and the average particle size in the dispersion exceeds the specified range of the present invention, and also has insufficient transparency in the visible light region and poor ultraviolet shielding ability. Comparative Example 3 was an example in which no dispersant was used. Without the dispersant, even if the zinc oxide powder had been hydrophobized, the dispersibility in the silicone oil was poor, and the zinc oxide fine particles were secondary aggregated. This causes coarsening, which reduces the visible light transmittance and poor ultraviolet shielding properties.

Next, examples of cosmetics using the ultrafine zinc oxide / silicone dispersion according to the present invention will be described. In addition, the makeup holding in the examples as the following cosmetics, S
PF (Sun Protection Factor) and PF (Protect
The evaluation / measurement method of ion Factor for UVA) is as follows.

Long-lasting makeup: Each of the cosmetics obtained in the examples was used for 12 professional paranets, and the degree of satisfaction was evaluated according to the following criteria. ：: 10 or more of 12 satisfied: ○ ⁺ : 12 8 to 9 out of 6 satisfied: 6 to 7 out of 12 satisfied Δ: 4 to 5 out of 12 satisfied ×: 3 or more out of 12 unsatisfied SPF, PF values: using SPF- _290S analyzer And
The measurement was performed according to the FDA (The Food and Drug Admistration) method (0.2 μl / cm ² was applied to a medical tape).

Example 4 The following ingredients (1) to (11) were weighed, kneaded at 80 ° C., and dissolved and dispersed (formulation liquid A). On the other hand, the following ingredients (1
5) is heated to 70 ° C, and the following ingredients (12) to
Add (14) and mix and dissolve (formulation B). The mixed liquids A and B were placed in a disper (same as above), stirred and emulsified, then defoamed and cooled to obtain a sample cosmetic (W / O type sun cream).

(1) Ultrafine zinc oxide / silicone dispersion 20 obtained in Example 1 (2) Decamethylcyclopentasiloxane 16.5 (3) Caprylic / capric triglyceride 12. 1 (4) trimethylsiloxysilicate 5 (5) polyoxyethylene / methylpolysiloxane copolymer 2 (6) octyl methoxycinnamate 5 (7) sorbitan monostearyl 3 (8) dimethyl distearyl ammonium bentonite 1 (9) isostearin Acid 1 (10) Methyl paraben 0.2 (11) 2-Phenoxyethanol 0.2 (12) 1,3-butylene glycol 5 (13) Sodium citrate 0.8 (14) Citric acid 0.2 (15) Water 28 The evaluation results of the obtained cosmetics were as follows: cosmetic durability: ○, SPF:
19, PF value: 13, SPF 15-20, PA ++
Display was possible.

Example 5 The following ingredients (1) to (12) were weighed, kneaded at 80 ° C., dissolved and dispersed, and the ingredients (13) to (16) were added thereto. Knead uniformly (mixed liquid A). On the other hand, a hydrogel of the following compounding raw materials (17) and (18) is prepared, and added to the above-mentioned compounding solution A and mixed and dissolved (mixing solution B). Further, the following compounding material (22) is heated to 70 ° C., and the following compounding materials (19) to (21) are added thereto and mixed and dissolved (mixing liquid C). The mixed liquids B and C were placed in a disper (same as above), stirred and emulsified, then defoamed and cooled to obtain a sample cosmetic (emulsion-type sunscreen cream).

(1) Ultrafine particulate zinc oxide / silicone dispersion obtained in Example 11 (2) Decamethylcyclopentacyclohexane 11.85 (3) Trimethylsiloxysilicate 5 (4) Mica (Silicone treatment) 3 (5) Kindelilla wax 3 (6) Celesin 4 (7) Microcrystalline wax 2 (8) Glyceryl tristearate 12 (9) Octyl methoxycinnamate 5 (10) Methyl paraben 0.2 (11) 2-phenoxyethanol 0.2 (12) Caprylic / capric triglyceride 3 (13) Titanium oxide (silicon treated) 9 (14) Bengala (silicon treated) 0.3 (15) Yellow iron oxide (silicon treated) 28 (16 ) Black iron oxide (silicon treatment) 0.3 (17) glyceryl monooleate 3 (18) sorbitol solution (70%) 5 (19) 1,3-butylene glycol 4 (20) citrate Sodium 0.6 (21) Citric acid 0.15 (22) Water 15 resulting cosmetic evaluation results makeup: ○, SPF:
10 to 15, PF + display was possible.

Example 6 The following ingredients (1) to (9) were weighed, heated, melted, and uniformly mixed. The ingredients (10) to (15) were added thereto, and the mixture was added to a roll mill. Knead evenly. The kneaded product was heated and re-melted, and the following ingredients (16) and (17) were added to the mixture to adjust the color.Then, the foam was floated and separated by slow stirring, and then slowly cooled to room temperature. (Oil-based stick type foundation).

Ingredients (% by weight) (1) Triisostearate malate 5 (2) Dimethylpolysiloxane (degree of polymerization 16, viscosity 10 cst at 25 ° C.) 10 (3) Liquid lanolin 4 (4) Microcrystalline wax 4.5 (5) Ceresin 10 (6) Carnauba wax 2 (7) Methyl paraben 0.1 (8) Sorbitan sesquiolate 2 (9) Octyl methoxycinnamate 5 (10) Titanium oxide (silicon treatment) 15 (11) Kaolin (silicon treatment) 15 (12) Talc (silicon treatment) 10 (13) Bengala (silicon treatment) 1.1 (14) Yellow iron oxide (silicon treatment) 2.6 (15) Black iron oxide (silicon treatment) 0 2 (16) Decamethylcyclopentasiloxane 2.5 (17) Ultrafine zinc oxide / silicone dispersion 11 obtained in Example 1 The evaluation results of the obtained cosmetic are as follows:
With 10 to 15, PA + display was possible.

Example 7 The following ingredients (1) to (13) were weighed, kneaded at 80 ° C., dissolved and dispersed, and the ingredients (14) to (19) were added thereto. Disperse uniformly with a disper (dispersion liquid A). On the other hand, the following compounding raw material (20) is heated to 70 ° C., and the following compounding raw materials (21) to (23) are added thereto and mixed and dissolved (mixture B). The mixture (B) was added to the dispersion (A), mixed and emulsified by a disper, then defoamed and cooled to obtain a sample cosmetic (liquid type eye shadow).

(1) Ultrafine zinc oxide / silicone dispersion obtained in Example 11 (2) Decamethylcyclopentasiloxane 15.1 (3) Caprylic / capric triglyceride 16. 8 (4) Trimethylsiloxysilicate 5 (5) Polyoxyethylene / methylpolysiloxane copolymer 2.9 (6) Octyl methoxycinnamate 5 (7) Sorbitan monostearyl 3 (8) Dimethyl distearyl ammonium bentonite 0.5 (9) Isostearic acid 0.5 (10) Liquid paraffin 3.9 (11) Trimethylolpropane triisostearate 0.5 (12) Methyl paraben 0.2 (13) 2-phenoxyethanol 0.2 (14) Titanium oxide (Silicon treatment) 2.1 (15) Bengala (Silicon treatment) 0.2 (16) Black iron oxide (Silicon treatment) 0.2 (17) Ultramarine Lou (silicon treatment) 1.6 (18) Red No. 201 0.3 (19) Titanium mica (silicon treatment) 5 (20) Water 20 (21) 1,3-butylene glycol 5 (22) Sodium citrate 0. 8 (23) Citric acid 0.2 The evaluation results of the obtained cosmetics were as follows:
With 10 to 15, PA + display was possible.

Example 8 The following ingredients (1) to (9) were weighed, heated and melted to mix uniformly, and then the ingredients (10) to (14) were added thereto, and the mixture was roll-milled. Knead evenly. The kneaded material is heated and re-melted, and the following compounding ingredients (16) to (19) are added to the mixture to adjust the color.Then, the foam is floated and separated by slow stirring, and is poured into a mold at 75 ° C. to be molded. Thus, a sample cosmetic (lipstick that does not fall off) was obtained.

(1) paraffin wax 4.5 (2) ceresin 3 (3) microcrystalline wax 3 (4) candelilla wax 4 (5) tocopherol acetate 0.2 (6) dimalate Isostearyl 10 (7) Trimethylolpropane triisostearate 10 (8) Glyceryl triisostearate 10 (9) Octyl methoxycinnamate 5 (10) Titanium oxide (silicon treatment) 1.3 (11) Bengala (silicon treatment) 1.3 (12) Black iron oxide (silicon treatment) 1.1 (13) Red 202 No. 1.6 (14) Red 223 0.1 (15) Titanium mica (silicon treatment) 2.5 (16) Deca Methylcyclopentasiloxane 17.4 (17) Trimethylsiloxysilicate 10 (18) Silica anhydride 4 (19) Ultrafine particulate zinc oxide / silicone dispersion obtained in Example 1 11 Cosmetic (lipstick) obtained Of the evaluation results, makeup: ○,
With SPF: 10 to 15, PA + display was possible.

[0073]

The present invention is constituted as described above, and essentially comprises ultrafine zinc oxide powder having been subjected to a hydrophobic treatment and having a specified average particle diameter, a dispersant, and a silicone oil as a dispersion medium. By containing them as components and preferably containing them in appropriate amounts, it is possible to obtain an ultrafine zinc oxide / silicone dispersion which is extremely useful for ultraviolet shielding cosmetics and the like. This makes it possible to obtain an ultraviolet shielding cosmetic having extremely high commercial value.

In particular, if a method of performing atomization treatment under predetermined pressure and flow rate conditions using a wet jet mill is adopted, the above-described high-quality ultrafine zinc oxide / silicone dispersion can be easily treated. It can be manufactured easily and with high productivity.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C083 AA122 AB172 AB211 AB212 AB232 AB242 AB432 AB442 AC012 AC022 AC122 AC132 AC152 AC241 AC242 AC262 AC302 AC342 AC352 AC372 AC422 AC442 AC482 AC792 AC842 AC911 AC912 AD151 AD152 AD161 AD162 AD171 AD172 AD512 AD662 BB26 CC01 CC05 CC12 CC13 CC14 CC19 DD11 DD23 DD30 DD32 EE17 FF01 FF05

Claims (11)

[Claims] 1. Ultrafine particles comprising ultrafine zinc oxide powder having an average particle diameter of 0.001 to 0.2 μm, a suspension containing a dispersant, and a silicone oil as a dispersion medium. Zinc oxide / silicone dispersion. 2. The dispersion according to claim 1, wherein the dispersion is ultrafine zinc oxide: 2
The ultrafine zinc oxide / silicone dispersion according to claim 1, comprising 0 to 60% by weight, a dispersant: 2 to 10% by weight, and a silicone oil: 30 to 78% by weight. 3. The dispersion according to claim 1, wherein the ultrafine zinc oxide has a surface subjected to a hydrophobic treatment with at least one selected from siloxanes and higher fatty acids. 4. The silicone oil is at least one selected from the group consisting of dimethyl silicone oil, cyclic dimethyl silicone oil, methylphenyl silicone oil, and trimethylsiloxysilicic acid.
A dispersion according to any one of claims 1 to 3. 5. The dispersion according to claim 1, wherein the dispersant is a polyether-modified silicone oil. 6. A suspension containing the zinc oxide powder surface-treated with a hydrophobizing agent, a dispersant, and a silicone oil as a dispersion medium is subjected to a wet jet mill to form a suspension of 65 to 25.
A method for producing an ultrafine zinc oxide / silicone dispersion, characterized in that the suspensions are caused to collide with each other and / or with a wall surface at a pressure of 0 MPa and / or a flow rate of 180 to 350 m / sec. 7. The suspension according to claim 1, wherein the zinc oxide powder: 20 to 6
7. A composition containing 0% by weight, a dispersant: 2 to 10% by weight, and a silicone oil: 30 to 78% by weight.
Production method described in 1. 8. The method according to claim 6, wherein the hydrophobizing agent is at least one selected from siloxanes and higher fatty acids. 9. The silicone oil is at least one selected from the group consisting of dimethyl silicone oil, cyclic dimethyl silicone oil, methylphenyl silicone oil and trimethylsiloxysilicic acid.
9. The method according to any one of items 1 to 8. 10. The method according to claim 6, wherein the dispersant is a polyether-modified silicone oil. 11. An ultraviolet shielding cosmetic comprising the ultrafine particulate zinc oxide / silicone dispersion according to any one of claims 1 to 5.