JPH03183620A - Zinc oxide and cosmetic material - Google Patents

Abstract

PURPOSE:To obtain the zinc oxide having good transparency and a high UV shielding effect and useful as cosmetic material by coating the surfaces of the fine particles of zinc oxide with the (hydro)oxide of Al Si, Zr of Sn. CONSTITUTION:The surfaces of the fine particles of zinc oxide having <=0.1mu average diameter are coated with 0.1-20wt.%, based on the zinc oxide, of one or plural kinds among the oxides or hydroxides of Al Si, Zr or Sn to obtain the zinc oxide. The average diameter of the fine particles of zinc oxide is controlled to <=0.1mu. The UV shielding effect is not sufficiently produced at >0.1mu, the visible rays are absorbed and scattered and the transparency is remarkably deteriorated. Cosmetic material having good preservability and sufficient smoothness are obtained by incorporating 0.1-40wt.% of the coated zinc oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to particulate zinc oxide and a UV-shielding cosmetic prepared by blending the same, specifically A12.Si.

Surface-modified zinc oxide in which the surface of finely divided zinc oxide is coated with Zr or Sn oxide or hydroxide to improve various physical properties, and cosmetics made by blending the same - "Prior art" The sunlight shining on the ground contains mid-ultraviolet rays (280~
32 orui; uv-B) and near ultraviolet light (325-4
00ne; UV-A). Among these, medium ultraviolet rays are known to cause inflammation such as erythema chickenpox on the skin, while near ultraviolet rays promote melanin production and cause browning of the skin. In order to deal with such adverse effects on the human body (skin), sunscreen cosmetics and sunscreen cosmetics containing ultraviolet screening agents have been known.

Ultraviolet screening agents used in such cosmetics include:
Broadly divided into benzophenone type, benzotriazole type,
They are classified into two types: ultraviolet absorbers such as salicylic acid, and ultraviolet scattering agents such as zinc oxide, titanium oxide, and cerium oxide. Among these, ultraviolet absorbers, which are mainly organic compounds, have an absorption edge around 330 to 350 na, so they do not have a sufficient shielding effect against near ultraviolet rays, and therefore, sunscreens are often used in cosmetics. There are many L). In addition, this ultraviolet absorber may be irritating to the skin, so if it is combined with 2 spears, it may cause skin allergies.
However, since the UV absorber itself deteriorates by absorbing UV rays, there are problems such as the UV a-blocking effect does not last long.

In addition to this, X, t L, the number of ultraviolet rays, which are mainly inorganic compounds,
1-1 (Since soil absorbs and scatters near-ultraviolet rays, it has the advantage of blocking ultraviolet rays over a wide area, including near-violet rays. Therefore, 1-1 Baked i
-+ +L- It is effective when blended into 11 products. Manokoko's ultraviolet ray number is 11' + 14 agent.
・Since it is an inorganic compound, it does not cause allergic reactions to the skin. 1 fish 1 with Nout')! A commonly used material is titanium oxide. Titanium oxide (
Because it has a high refractive index of 25, it has good hiding power and is very eye-catching, so it is used in cosmetics and is transparent! 7g is lost and the finish becomes whitish and unrecognizable. Since titanium oxide has various disadvantages as described above, it has been proposed to use zinc oxide in place of titanium oxide.

Here, FIG. 1 shows the respective spectral reflectances of ultrafine titanium oxide having an average particle size of about 0.02 μm and ultrafine zinc oxide having the same size. From Figure 1, zinc oxide is 400g.
Since absorption begins near x and has an absorption edge near 380 μm, it can be seen that it has a shielding effect over a wider ultraviolet range than titanium oxide.

Furthermore, since zinc oxide has a refractive index of about 1.9, which is considerably smaller than titanium oxide, the degree of scattering is reduced and the transparency greatly exceeds that of titanium oxide. If the particle size is adjusted to ultrafine particles of 0.1 μm or less, the wavelength will be much smaller than the wavelength of visible light, so visible light will hardly be absorbed, resulting in increased transparency. In this way, fine-particle zinc oxide has superior features compared to conventional UV-shielding materials, namely titanium oxide, in terms of a wider UV-shielding area, transparency, safety for the skin, and durability of the UV-shielding effect. I have it.

``Is it an invention or an explanation?'' Since the only L2 level is L2, when this fine particle zinc oxide is added to cosmetics as an ultraviolet ray, I, and L agent, the following results are obtained. There are some problems to mention.

Fine particles of lead oxide (11E) have a high catalytic activity, but because they are fine particles and have a large surface area, their catalytic activity is limited. When this fine-particle zinc oxide is blended into cosmetics, it is usually mixed with a fiR vehicle, but since the fine-particle zinc oxide has catalytic activity as mentioned above, it is difficult to preserve it. During this period, fine particulate zinc oxide alters the organic vehicle and functions as a U-filter catalyst, which improves the preservation of cosmetics (7).
It will ruin the forest as it used to be.

Furthermore, when fine-particle zinc oxide is blended into cosmetics, the smoothness of the cosmetics is reduced. 1- In other words, zinc oxide originally has a poor adhesive strength and a poor coefficient of dynamic friction and slippage compared to alumina and the like. Since these become fine particles, the coefficient of dynamic friction becomes thicker than ever before, resulting in a decrease in smoothness and a worsening of the feel.

Since the invention was made to solve the above problems,
The purpose is to provide cosmetics with good transparency, high UV shielding effect, long shelf life and sufficient smoothness, and to provide zinc oxide to obtain this. It's about doing.

"Means for Solving the Problems" In the zinc oxide according to claim 1 of the present invention, 0.1μ
Al, Si, Z? Alternatively, the above-mentioned problem was solved by coating zinc oxide with one type of Sn oxide or hydroxide or 'flk type in a weight ratio of 0.1 to 20%.

In addition, in the cosmetic composition according to claim 2, the solution to the above problem is that the zinc oxide according to claim I is blended in an amount of 0.1 to 40% by weight.

The present invention will be explained in detail below. The zinc oxide according to claim 13L of the present invention is a particulate sacrificial lead oxide coated with a metal hydroxide, which seems to be a metal oxide.

The fine particle zinc oxide to be blended has an average particle size of 0.1
A material of μm or less is used. Here, the average particle size is 0.1
The reason why it is set to be less than .mu.m is because if the wavelength is larger than this, the ultraviolet shielding effect will be insufficient, and if the wavelength approaches the visible light, visible light will also be absorbed and scattered, resulting in a significant decrease in transparency.

Various methods can be adopted to produce such fine zinc oxide particles, but for example, it may be produced based on the method for producing ultrafine zinc oxide proposed earlier by Ganto Ohta (Japanese Patent Application No. 1130422). can. That is, in this method, hydrogen sulfide is passed through a mixed solution of zinc acid salt and ammonium acetate, soluble salts are removed from the resulting precipitate, the precipitate is then fractionated into a non-aqueous solvent, and this is heated in an autoclave for 250 min. The gas content is removed by heating at ~400°C, and the resulting dry powder is then heat-treated at 500~800°C to obtain ultrafine zinc oxide particles.

As the metal element of the metal oxide or metal hydroxide used to coat the particulate zinc oxide, Af2. S
One or a combination of i, Zr, and Sn is used. Among these, the oxides or hydroxides of si and zr mainly reduce the catalytic activity of zinc oxide and inactivate it by coating the zinc oxide. On the other hand, A12. Zr, Sn
The oxide or hydroxide coats zinc oxide to reduce its coefficient of dynamic friction. In other words, this is AQ.

7.? This is because the coefficient of dynamic friction of Sn oxide or hydroxide is small. Furthermore, the crystal type of fine-particle zinc oxide is 60,000 particles, and the particle shape is prismatic. becomes rounded and approaches a spherical shape as a whole, so the decrease in the coefficient of dynamic friction mentioned above becomes even more remarkable. By incorporating zinc oxide coated with these oxides or hydroxides into cosmetics, the slippage of the cosmetics can be improved.

The coating m of the oxide or hydroxide on the surface of zinc oxide should be in the range of 0.1% by weight to 20% by weight. That is, if the coating amount is less than 0.1% by weight, the effect of the surface coating will not be sufficiently exhibited, and it will not be possible to sufficiently reduce the catalyst activity or improve the coefficient of dynamic friction.
On the other hand, if it exceeds 20% by weight, the amount of zinc oxide contained will be relatively reduced and the ultraviolet shielding effect will not be sufficient.

Oxidation with hydroxide, such as Si or Zr oxide [2] The coating of the milead surface is carried out, for example, in the case of Si oxide, by the following procedure.

First, add a predetermined amount of particulate zinc oxide to an aqueous solution of sodium silicate overnight, stir the solution strongly to form a suspension, and gradually add diluted hydrochloric acid to the aqueous solution while paying attention to the pH of the solution. Then, when p I-1 reaches about 7, the addition is stopped and the mixture is allowed to stand for a while.

Then, Si oxide gradually precipitates on the surface of the zinc oxide particles, forming a film. Next, this suspension? −Q=
:m7+k+,h,'+-k&Nil
% +-= +^c: Or -y= ++r+ hk
Dry and get dry powder.

Also, A12. The surface of zinc oxide is coated with a hydroxide such as an oxide of Zr or Sn, for example, in the case of an oxide of AQ, by the following procedure.

First, a predetermined amount of particulate zinc oxide is added to an aqueous solution of sodium aluminate, the solution is strongly stirred to form a suspension, and a diluted hydrochloric acid solution is gradually added dropwise while being careful not to cause the pH of the solution to fall below 7. . Then, on the surface of the zinc oxide particles,
A Q t O3 gel precipitates. After the dropwise addition is completed, the mixture is allowed to stand for a while, filtered and washed, and further heated and dried at a temperature of about 105° C. to obtain a dry powder.

The cosmetic according to claim 2 contains 0.1 to 40% by weight of zinc oxide after the coating treatment. Here, the cosmetics are intended to prevent sunburn and IL, and various forms such as creams, lotions, lactic acid, etc. are used. The reason why the amount of zinc oxide was set to 0.1 to 40% by weight was that less than 0.1% by weight would result in acid loss.
1) 4← Su? ↓, h ^bm beat)
This is because the effects of zinc oxide on the cosmetics themselves are not fully demonstrated, and if the concentration exceeds 40% by weight, the effectiveness of the cosmetics themselves decreases, and the cost of zinc oxide after coating is high. This is because the cost becomes high.

The catalytic activity of the zinc oxide obtained in this way and after the coating treatment is lower than that without the coating,
In addition, the properties of fine-particle zinc oxide have been greatly improved, including a reduction in the coefficient of dynamic friction. If this is blended to produce an ultraviolet-shielding cosmetic composition for preventing sunburn, it will have the following advantages over conventional cosmetic compositions.

4. However, by incorporating conventional fine particle zinc oxide into cosmetics,
When used in combination with various cosmetic bases, if the catalytic activity is high, such as fine particulate zinc oxide, one
By accelerating the decomposition and polymerization of bokmin, zinc oxide-containing cosmetics cause changes over time such as discoloration, hardening, and generation of off-flavors. However, in cosmetics containing zinc oxide after the two-layer coating treatment, the catalytic activity of zinc oxide has decreased, so the above-mentioned changes over time are not accelerated, and the cosmetics are It is possible to make a difference over the course of one's lifespan. Also,
Conventional fine-particle zinc oxide has a large coefficient of dynamic friction, so when incorporated into cosmetics, it causes poor slippage, making it impossible to obtain a smooth and pleasant feel when used. However, cosmetics containing zinc oxide after coating treatment have a small dynamic friction coefficient, and therefore can provide a smooth feel when used. Furthermore, the cosmetic containing zinc oxide after this coating treatment is extremely transparent and has a shielding effect over almost the entire ultraviolet region, including the near ultraviolet region, which is very close to the visible region.

(Experimental Example) Changes in catalytic activity before and after surface coating treatment of particulate zinc oxide were investigated, and the results are shown in Table 1. As a measure of the catalytic activity, the conversion rate of isopropyl alcohol to acetone by dehydrogenation reaction when using a microreactor was used.

No.! Table 1 (Rano with an average particle size of 0.015 μR was used as zinc oxide.) From Table 1, uncoated zinc oxide has an isopropyl alcohol conversion rate of 58 mol%, and has a large catalytic activity. It can be seen that it has On the other hand, Sin or Zr0. The catalytic activity of zinc oxide coated on the surface was significantly reduced, confirming the effect of the surface coating treatment.

In addition, fine particle zinc oxide, A17. The changes in the coefficient of dynamic friction before and after surface coating treatment with oxides or hydroxides such as Zr, Sn, etc. were investigated, and the results are shown in Table 2.

The coefficient of dynamic friction was measured by moving a loaded movable attachment back and forth over the zinc oxide particles and reading the shear stress with a strain meter.

Table 2 (However, as the zinc oxide, Rano with an average particle size of 0.015 μm was used.) From Table 2, it can be seen that zinc oxide without a coating has a dynamic friction coefficient of 0.95, which is extremely large, partly because the particle size is small. Therefore, when cosmetics are prepared by blending them, it is presumed that the slippage of the cosmetics will be poor. On the other hand, when the surface of zinc oxide is coated with A (2zO3゜ZrOt, SnOt), the coefficient of dynamic friction is about 1/2 to 173 compared to that without coating, so these are mixed. It can be inferred that if a cosmetic is prepared using this method, the slipperiness will be significantly improved compared to when uncoated zinc oxide is blended.

"Example" Examples of the cosmetic according to claim 2 of the present invention are shown below.

(Example 1) A cream was prepared using the following formulation.

Fine particle zinc oxide 5% by weight (5iOy on the surface of zinc oxide with an average particle size of 0.02μm)
3% by weight, A (Shinobu coated with 2% by weight of !to3) Kaolin 2% by weight Cetyl alcohol 3% by weight Vaseline
6% by weight liquid paraffin
12% silicone oil by weight
2% by weight glycerol monostearate 2.5% by weight polyoxyethylene
(25 mol) Cetyl alcohol ether 2.
5% by weight Propylene gellicol Purified water Fragrance Pigment Preservative 6% by weight 59% by weight Appropriate amount Appropriate amount The cream was prepared according to the following procedure.

First, fine particulate zinc oxide with an average particle size of 0.02μ is prepared, and the surfaces of these are coated with Sin and A by the method described above.
Each was coated with 12 tOz. In addition, the amount of coverage is 5i
de was 3% by weight, and AILOs was 2% by weight. next,
The coated fine particles of zinc oxide, kaolin, and pigment were mixed in a blender to form a powder part.

Next, add propylene glycol to purified water and heat at 70°C.
, add the above powder part and disperse with a homomixer,
It was made into an aqueous phase. Further, other components in the above formulation were mixed, heated and dissolved, and kept at 70°C to form an oil phase.

Thereafter, an oil phase was added to the aqueous phase, uniformly emulsified and dispersed using a homomixer, and after emulsification, the mixture was stirred while cooling to obtain a cream.

When the resulting cream was applied to the skin, it blended well with the skin and had a smooth feel. Furthermore, when this cream was irradiated with ultraviolet rays to examine its shielding effect, it was confirmed that it had a sufficient ultraviolet shielding effect.

(Example 2) A lotion was prepared using the following formulation.

Fine particle zinc oxide 5% by weight (5iO
Coated with 3% by weight of y and 5% by weight of Zr0t. ) Polyethylene glycol 400 15% by weight glycerin 7% by weight polyoxyethylene (60 mol) Hydrogenated castor oil
1.5% by weight ethyl alcohol
50% by weight Jouseisui
21.5% fragrance by weight
The appropriate amount dye appropriate amount lotion was prepared using the following procedure.

First, fine-particle zinc oxide with an average particle size of 0.02 μm is prepared, and SiOx and Z are applied to the surface by the method described above.
rOs and were coated, respectively. Note that the coating amount is SiOx
was set at 3% by weight, and ZrO was set at 5% by weight. Next, polyethylene glycol and glycerin were added to purified water and dissolved therein to form an aqueous phase. Additionally, other components except the dye were added to ethyl alcohol and dissolved, forming an oil phase.

Thereafter, the above-mentioned coating-treated fine zinc oxide and oil phase were added to the aqueous phase to solubilize it, and the mixture was further colored with a dye to obtain a lotion.

When the resulting lotion was applied to the skin, it spread well and had a smooth feel. Furthermore, when this lotion was irradiated with ultraviolet rays to remove its shielding effect, it was confirmed that it had a sufficient ultraviolet shielding effect.

(Example 3) A milky lotion was prepared using the following formulation.

@La-r Zinc oxide 7% by weight (f
On the surface of zinc oxide with a diameter of 0.0211 ff,
7. Otsu Q) coated with 3% rO and 2% S n O2 by volume. ) Stearic acid 3% by weight Cedyl alcohol 2% by weight Vaseline
6% by weight Norikonura
2 tons m% liquid paraffin
12% by weight taliceryl monostearate Nisder-1 myrioquinoethylene heptanooleic acid ester polyethylene glycol 1500 Veegum 1+'r water fragrance 1v preservative 15% by weight (25 moles 1.5% by weight 4% by weight 0. 5% by weight 605% by weight Appropriate amount Electrical emulsion was prepared (performed in the following steps).

First, fine particle zinc oxide with a flat particle size of 0.0271 m was prepared, and '1 rot' was applied to the surface by the method described above.
and S n Oz, respectively. The coating amount was 3% by weight of ZtO* and 2% by weight of Sr+Ot.

Next, bu-a-pyrene glycol was added to the purified water and dissolved by heating, then the coated zinc oxide and Beega were added, uniformly dispersed with a homomixer, and kept at 70°C to form an aqueous phase. . Further, - the other components in the above formulation were mixed, heated and melted and kept at 70°C to form the Le 11 phase.

After that, add the oil phase to the above water phase, emulsify and disperse it uniformly with a homomixer, and after emulsification, mix it at 35 degrees.
A milky lotion was obtained by cooling to C.

When the resulting emulsion was applied to the skin, it spread well and had a smooth feel. Further, when this emulsion was irradiated with ultraviolet rays and its shielding effect was examined, it was confirmed that the emulsion had an ultraviolet ray shielding effect of 1 minute.

"Effects of the Invention" As explained above, the zinc oxide used in the present invention is
On the particle surface of fine-particle zinc oxide having an average grain size -F of less than μm, oxides of AQ, Si, Zr and Sn (one or more of the above hydroxides are added to the zinc oxide). χ, t L weight is coated with 1 to 20% O.Then, the catalytic activity of zinc oxide decreases compared to when it is not coated. , and the coefficient of dynamic friction is small.

Claim F (I 2 Cosmetics IJ, 1. Since it contains 0.1 to 40% lead oxide 1111 after overturning, it is very transparent and (
14゜゛rum, and the catalytic activity of the blended zinc oxide.
Since the coefficient of kinetic friction of zinc oxide is low, it does not accelerate the aging of other ingredients and has a high shelf life.Furthermore, the coefficient of dynamic friction of the zinc oxide is small, so when used It gives a smooth feel.

[Brief explanation of drawings]

'tcc I 11! /l 1 15 1%
It is a graph showing the spectral reflectance of ultrafine zinc oxide particles of size Zr-M9.

Claims (2)

[Claims] (1) One or more of the oxides or hydroxides of Al, Si, Zr, or Sn are added to the surface of fine zinc oxide particles having an average particle diameter of 0.1 μm or less at a weight relative to zinc oxide. Zinc oxide characterized by being coated with a ratio of 0.1 to 20%. (2) 0.1 to 40% by weight of zinc oxide according to claim 1;
Cosmetics characterized by being formulated with