JP2007182382A - Method for producing ultraviolet-screening zinc oxide excellent in transparency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To find a metal oxide which enables effective UV-screening; i.e. which has excellent screening ability against ultraviolet rays, particularly against long-wavelength ultraviolet rays, as well as excellent visible-light transmission and to provide a method for producing thereof. <P>SOLUTION: The method for producing zinc oxide aggregate is obtained by causing a reaction between zinc ions (Zn<SP>2+</SP>), carbonate ions (CO<SB>3</SB><SP>2-</SP>), and hydroxide ions (OH<SP>-</SP>) in water serving as a solvent while the pH of the aqueous reaction solution is maintained at 7-9 and the molar ratio of hydroxide ion to carbonate ion is fixed to be not greater than 4 (excluding 0) and calcinating basic zinc carbonate formed in the aqueous reaction solution. Furthermore, the zinc oxide aggregate is crushed in order to obtain a method for producing zinc oxide, so as to find the solution of the problem. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In particular, the present invention relates to a method for producing zinc oxide which is excellent in shielding effect against long wavelength ultraviolet rays (UV-A).

  Specifically, the present invention is an oxidation in which primary particles having an average particle diameter of 50 to 100 nm are aggregated in a planar shape, and further have an ultraviolet shielding ability, particularly a long wavelength ultraviolet shielding ability, and an excellent visible light transmittance. This invention relates to a method for producing zinc. Zinc oxide produced by the production method of the present invention is excellent in transparency and ultraviolet shielding properties, and is suitable for blending into an external composition.

  In recent years, it has become widely known about the adverse effects of ultraviolet rays in sunlight on the human body, and countermeasures have been studied from various aspects.

  Ultraviolet rays are dermatologically classified into long wavelength ultraviolet rays (UV-A) of 320 to 400 nm, medium wavelength ultraviolet rays (UV-B) of 290 to 320 nm, and short wavelength ultraviolet rays (UV-C) of 290 nm or less.

  Among these ultraviolet rays, UV-C is an ultraviolet ray that has a detrimental effect on humans and other living organisms, but for now it is absorbed by the ozone layer in the upper atmosphere and reaches the ground directly. There are few (however, there are concerns that the recent destruction of the ozone layer may adversely affect the natural world).

  On the other hand, UV-A and UV-B, which are ultraviolet rays that reach the ground and are directly exposed to humans, are known to have a number of actions on the human body.

  In these effects, there are overwhelmingly more adverse effects on the human body than beneficial effects such as promoting the production of vitamin D in the body.

Among UV-A and UV-B, it was UV-B that was focused on from an early stage and actively developed its protective agent. Recently, however, attention has been paid to the adverse effects of UV-A on skin aging, and various means for effectively shielding UV-A have been proposed.
JP-A-4-280814

  Currently, when an inorganic substance is used as a means for shielding ultraviolet rays, typically, a metal oxide having excellent ultraviolet shielding effect such as titanium dioxide or zinc oxide is mainly contained in an external composition such as cosmetics, A method of protecting the human body from ultraviolet rays in sunlight by the ultraviolet shielding effect of the metal oxide has been performed. However, if this metal oxide is used to improve the shielding effect of UV-A that is close to the wavelength of visible light, the nature of the metal oxide generally scatters visible light. The problem arises that the coated surface of the coating becomes unnaturally white. For this reason, there is a limit to the content of the metal oxide in the external composition, and as a result, a sufficient UV-A shielding effect has not been exhibited in the external composition.

  That is, at present, it cannot be said that the UV-A shielding means has been sufficiently established.

  The problem to be solved by the present invention is to provide a metal oxide that can more effectively shield ultraviolet rays, has excellent ultraviolet shielding ability, particularly UV-A shielding ability, and has excellent transparency to visible light. Finding the means.

  The present inventor has intensively studied to solve this problem. As a result, it was found that zinc oxide having a characteristic form that can be produced by a specific production method has a very excellent UV-A shielding ability and an excellent transparency to visible light. completed.

That is, the present invention uses zinc as a reaction solvent to maintain zinc ions (Zn ²⁺ ), carbonate ions (CO ₃ ²⁻ ), and hydroxide ions (OH ⁻ ) at a pH of 7-9 in the reaction aqueous solution, The molar ratio of hydroxide ion to carbonate ion is set to 4 or less (excludes 0) for carbonate ion 1 to react with carbonate ion 1, and the basic zinc carbonate produced in this reaction aqueous solution is calcined. The present invention provides a method for producing a zinc oxide aggregate (hereinafter also referred to as this production method).

  Furthermore, by pulverizing the zinc oxide aggregate produced by the production method, zinc oxide having excellent transparency and ultraviolet shielding properties (hereinafter also referred to as the present zinc oxide) can be produced.

Zinc oxide produced by the present production method is a zinc oxide primary particles having an average particle diameter of 50~100nm are assembled into a planar shape, and its _{lnT 360nm / lnT 400nm (T xnm} : Xnm transmitted light Zinc oxide having a transmittance value of 10 or more, particularly the above zinc oxide having the following morphological characteristics.

(1) Zinc oxide having an uneven surface with a thickness corresponding to one of these primary particles, in which primary particles of zinc oxide having an average particle diameter of 50 to 100 nm are gathered in a planar shape.
(2) The passing diameter of the zinc oxide described in the above (1) is 0.01 to 5 μm.
(3) Irregularities of 10 to 200 nm are irregularly formed every 10 to 200 nm on the edge portion of the zinc oxide surface described in (1) and (2) above.

  Here, the “passing diameter” of zinc oxide means a distance (longest diameter) between two points selected so that the distance is maximum in zinc oxide in which primary particles are assembled in a planar shape.

In this production method, water is used as a reaction solvent, zinc ions (Zn ²⁺ : provided by a strong acid salt of zinc such as zinc chloride, zinc sulfate, zinc nitrate, etc.), carbonate ions (CO ₃ ^2- : for example, (Provided by a carbonate such as sodium carbonate or potassium carbonate) and hydroxide ions (OH ⁻ : donated by a strong base such as sodium hydroxide or potassium hydroxide). And the molar ratio of hydroxide ion to carbonate ion is set to within 4 times (excluded when hydroxide ion is 0 mol, approximately 2.5 to 3.5 times) and allowed to react (preferably Is reacted at 40 ° C. to 70 ° C.), and the basic zinc carbonate formed in the reaction aqueous solution is calcined (150 ° C. to 450 ° C.), whereby the zinc oxide aggregate according to the present invention (hereinafter referred to as the present zinc oxide coagulum) Collection Is manufactured).

  In addition, the present inventor provides an ultraviolet shielding composition containing the above zinc oxide, which can be used as an external composition such as a makeup cosmetic or a sunscreen cosmetic, and the above zinc oxide. An ultraviolet shielding composition containing the aggregate is also provided.

When the ultraviolet shielding composition containing the present zinc oxide aggregate is used as an external composition, the frictional force generated by applying the zinc oxide aggregate contained in the external composition on the skin, by milling above, in the ground zinc oxide, lnT _360nm / lnT _400nm: the value of (T _{x nm} transmittance of transmitted light of X nm) is 10 or more, expressed as, transparency and UV shielding property Can be exerted on the skin of the user of the composition for external use.

  INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for producing zinc oxide aggregates and zinc oxide, which is excellent in transparency and in particular, a shielding effect against long wavelength ultraviolet rays (UV-A).

Zinc This oxidation, as described above, a zinc oxide primary particles having an average particle diameter of 50~100nm are assembled into a planar shape, and its _{lnT 360nm / lnT 400nm (T xnm} : transmitted light of Xnm Of zinc oxide having a value of 10 or more.

In the present invention, lnT _{360 nm} / lnT _{400 nm} of zinc oxide: the value of (T _{x nm} transmittance of transmitted light of X nm) is the zinc oxide is whether the indicator has the desired properties.

That is, lnT _360nm / lnT _400nm is an index that represents the relationship between the shielding property against long-wavelength ultraviolet rays and the transmission property against visible light. That is, by taking the ratio of the logarithm of transmittance for long-wavelength ultraviolet light (λ = 360 nm) to the logarithm of transmittance for visible light (λ = 400 nm), the transparency of the target zinc oxide and the shielding against long-wavelength ultraviolet light are taken. Both gender factors are taken into account at the same time.

If the value of this lnT _{360 nm} / lnT _{400 nm} is large, excellent transmittance high transparency to visible light, and the transmittance of UVA is low, the better the shielding of the long-wave ultraviolet light.

In the present invention, the value of this lnT _{360 nm} / lnT _{400 nm} is, as one of main themes to provide a manufacturing method of the present zinc oxide is 10 or more.

In other words, this zinc oxide is zinc oxide having at least one unit of “zinc oxide in which primary particles are assembled in a planar shape”, and the value of “lnT _360nm / lnT _400nm ” is 10 or more. The shape as a whole is not particularly limited as long as it has the property “. The “zinc oxide aggregate” and this zinc oxide have the property that the present zinc oxide has a value of “lnT _360nm / lnT _{400 nm} of 10 or more”, whereas “zinc oxide aggregate” Such a difference is that the shielding property against long-wavelength ultraviolet light and the transmission property against visible light are not accompanied by itself. In this specification, “%” is attached when the transmittance is expressed in percentage. In other cases, it is handled as a number of 1 or less.

The present zinc oxide generally contains zinc ion (Zn ²⁺ ), carbonate ion (CO ₃ ²⁻ ), and hydroxide ion (OH ⁻ ) using water as a reaction solvent, maintaining the pH of the reaction aqueous solution at 7 to 9, The reaction is carried out by setting the molar ratio of hydroxide ion to carbonate ion within 4 times (except when the hydroxide ion is 0 mol), and firing the basic zinc carbonate produced in the reaction aqueous solution. The zinc oxide aggregates of the form in which the present zinc oxide aggregates with each other like a carnation flower (hereinafter referred to as the present zinc oxide aggregates) are usually produced by known means. Manufactured by grinding.

  Examples of the zinc ion donating substance include strong zinc acid salts such as zinc chloride, zinc sulfate, and zinc nitrate. Examples of the carbonate ion donating substance include carbonates such as sodium carbonate and potassium carbonate. Furthermore, examples of the hydroxide ion donating substance include strong bases such as sodium hydroxide and potassium hydroxide.

  Usually, the basic zinc carbonate produced | generated by the said process maintains the aqueous solution in which the zinc ion melt | dissolves, the aqueous solution in which the carbonate ion and the hydroxide ion are melt | dissolving, and the pH of reaction aqueous solution is 7-9. Thus, it can manufacture by mixing.

  The molar ratio of the carbonate ion to the hydroxide ion is preferably 4 or less (except when the hydroxide ion is 0 mol) with respect to the carbonate ion 1, and is also a strong base with respect to the carbonate 1. Is particularly preferably 2.5 to 3.5.

  In this molar ratio of both alkali ions, when carbonate ions become excessive, the carbonate ions that remain without reacting in the reaction solution accumulate, and as a result, the microscopic form of the above-mentioned zinc oxide aggregates is increased. It is not preferable because it becomes a card shape or a plate shape instead of a carnation flower shape, and even if this is pulverized, only zinc oxide having reduced permeability to visible light is provided. In addition, when the hydroxide ions become excessive, huge rice-like particles are observed in the above zinc oxide aggregate, and even if this is pulverized, the UV-A shielding ability and the visible light permeability are extremely reduced. This is not preferable because it provides zinc oxide.

  The aspect of the basic zinc carbonate production step in the reaction aqueous solution is not particularly limited as long as the consumption of carbonate ions in the reaction aqueous solution is appropriate. That is, as described above, an alkaline mixed solution containing carbonate ions and hydroxide ions and an acidic zinc ion solution can be dropped, and the carbonate ion solution and the hydroxide ion solution are dropped separately. In consideration of the accumulation of carbonate ions in the aqueous reaction solution over time, the amount of carbonate ions in the alkaline mixed solution may be gradually reduced according to the amount of carbonate ions accumulated in the reaction aqueous solution. Is possible.

  As described above, the pH of the aqueous reaction solution is suitably 7-9. When this pH exceeds 9, in the above-mentioned zinc oxide aggregate to be produced, rice-like particles and tetrapot-like particles are generated, and even if this is pulverized, UV-A shielding ability and transparency to visible light are generated. This is not preferable because it provides zinc oxide having a very low level. Moreover, when this pH is less than 7, the production | generation efficiency of basic zinc carbonate will fall extremely, and it is unpreferable.

  Moreover, it is preferable that the temperature of aqueous reaction solution is 40-70 degreeC. When this temperature is less than 40 ° C., the production efficiency of basic zinc carbonate decreases, and when it exceeds 70 ° C., rice-like particles and tetrapot-like particles are generated, and UV-A shielding ability and transparency to visible light are generated. This is not preferable because it provides zinc oxide having a very low level.

  Calcination for producing the present zinc oxide aggregate from basic zinc carbonate is preferably carried out in the range of approximately 150 ° C to 450 ° C. When the firing temperature exceeds 450 ° C., the sintering of the zinc oxide particles proceeds excessively, and the produced zinc oxide aggregate is not preferable because it does not have the desired properties in the present invention. In addition, if the firing temperature is less than 150 ° C., the progress of the decarboxylation reaction due to firing becomes extremely slow, and the practicality is poor, which is not preferable.

  In addition, the zinc oxide derived from the zinc oxide aggregate obtained by setting the firing temperature to a low temperature tends to have better transparency to visible light, but it balances with the above-described decarboxylation reaction progress rate. In view of the above, the firing temperature is preferably 250 ° C to 400 ° C, and particularly preferably around 250 ° C to 260 ° C.

  The firing time can be appropriately selected according to the set firing temperature. That is, when the firing temperature is set low, firing for a long time is required (for example, firing at 150 ° C. requires several days), and when it is set high, the decarboxylation reaction is completed in a short firing time. (For example, the decarboxylation reaction is completed by baking for several hours at 250 ° C.).

  Thus, by firing basic zinc carbonate, it is possible to obtain the present zinc oxide aggregate in which the present zinc oxide is aggregated so as to have a flower-like microscopic form of carnation.

  The microscopic form of the present zinc oxide aggregate is a carnation flower shape (refer to an electron micrograph image described later), and the overall form of one unit of the aggregate is the reaction conditions described above. It can be changed depending on the case, and is not particularly limited.

  By pulverizing the present zinc oxide aggregate obtained through the above-described steps, the present zinc oxide can be produced.

  As the pulverizing means, a conventionally known pulverizing means used in powder pulverization can be used. Specifically, a three-roller, an ultrasonic crusher, a bead mill, a motor mill, a ring mill, an atomizer, a pulverizer, etc., preferably, mechanical grinding by a three-roller, motor mill is applied to the zinc oxide aggregate. By performing this, the present zinc oxide can be produced.

In this way, the average primary particle diameter is 50~100nm is a zinc oxide and forming a planar shape, and its _{lnT 360nm / lnT 400nm (T xnm} : transmittance of transmitted light of X nm) of The present zinc oxide having a value of 10 or more, excellent shielding property against UV-A, and excellent transparency to visible light is provided.

This zinc oxide has the following appearance (see the examples described later).
(1) Zinc oxide having an uneven surface with a thickness corresponding to one of these primary particles, in which primary particles of zinc oxide having an average particle diameter of 50 to 100 nm are assembled in a planar shape.
(2) The passing diameter of the zinc oxide described in the above (1) is 0.01 to 5 μm.
(3) Irregularities of 10 to 200 nm are irregularly formed every 10 to 200 nm on the edge portion of the zinc oxide surface described in (1) and (2) above.

  The zinc oxide and zinc oxide aggregates described above are treated with fatty acid soap such as aluminum stearate treatment and zinc myristate treatment as necessary; wax treatment such as candelilla wax treatment and carnauba wax treatment; Hydrophobic treatment by commonly known surface treatment methods such as methylpolysiloxane treatment, silicone treatment such as cyclic silicone oil treatment; fatty acid dextrin treatment such as dextrin palmitate treatment; various fatty acid treatments such as myristic acid treatment and stearic acid treatment To give water repellency.

  The present invention provides an ultraviolet shielding composition (hereinafter referred to as the present ultraviolet shielding composition) containing the present zinc oxide and / or the present zinc oxide aggregate thus obtained and having an ultraviolet shielding effect. .

  The present ultraviolet shielding composition is a composition having at least one purpose of shielding ultraviolet rays (which is a concept including scattering and absorption). The embodiment is not particularly limited. Specifically, the composition for external use which is externally applied to the skin such as cosmetics and protects the human body from ultraviolet rays; the resin composition having an aspect such as a resin having an ultraviolet shielding effect; A coating composition or the like for imparting an effect is exemplified as the present ultraviolet shielding composition.

  Among the modes that the present ultraviolet shielding composition can take, the present zinc oxide, which is contained as an essential component, has high ultraviolet shielding ability and transparency. It is particularly suitable for being used as

  Hereinafter, the composition for external use according to the present invention (hereinafter referred to as the composition for external use) will be described.

  The blending amount of the zinc oxide and / or the zinc oxide aggregate in the composition for external use should be appropriately blended according to the specific form of the composition for external use, etc., but is generally 0 with respect to the composition. 0.001% by weight or more, usually from 10 to 30.0% by weight. When the blending amount is less than 0.001% by weight with respect to the composition, it is often difficult to impart an expected UV-A shielding effect to the external composition.

  The upper limit of blending is about 30.0% by weight with respect to the composition as described above, but this amount is merely a guide and can be up to 100% by weight. As described above, since the present zinc oxide is highly transparent to visible light and excellent in transparency, even if it is incorporated in a large amount in a composition for external use, it is not excessively white at the time of use. It is possible to mix | blend in a composition for external use much rather than.

  Thus, by including the present zinc oxide and / or the present zinc oxide aggregate in the composition for external use, it has an excellent UV-A shielding effect at the time of use and is excellent in transparency. A composition is provided.

  In addition, since the above-described excellent UV-A shielding ability and excellent visible light transmittance are recognized before use, the composition for external use containing the present zinc oxide is excellent in transparency.

  On the other hand, the composition for external use containing the present zinc oxide aggregate is accompanied by the above-described excellent UV-A shielding ability and excellent visible light transmittance as it is. Therefore, it is difficult to exhibit the desired effect, and the above-described effect can be exhibited only by the use.

That is, the composition for external use containing the present zinc oxide aggregate is crushed on the skin by the frictional force generated by applying the zinc oxide aggregate contained in the external composition on the skin. by, in this ground zinc oxide, the values of lnT _{360 nm} / lnT _{400 nm} is 10 or more, represented, transparency and UV shielding property, it is exerted on the skin of a user of the external composition as a Is possible.

  In this invention, the usage method of this composition for external use is also provided in this way.

  In the composition for external use, as long as the desired effect of the present invention is not impaired, other components usually incorporated in the composition for external use such as cosmetics can be blended.

  For example, petrolatum, lanolin, ceresin, carnauba wax, candelilla wax, solid or semi-solid oil such as higher fatty acid, higher alcohol, fluid oil such as squalane, liquid paraffin, ester oil, triglyceride, oil such as silicone oil, sodium hyaluronate , Humectants such as glycerin, surfactants such as cationic surfactants and nonionic surfactants, pigments, preservatives, fragrances, activators, and ultraviolet shielding agents other than the present zinc oxide can be appropriately blended.

  The composition for external use can take the form of powder, cake, pencil, stick, ointment, liquid, etc. For example, facial cosmetics such as skin lotion, emulsion, cream, etc .; foundation Makeup cosmetics such as lipstick, eye shadow, blusher, eyeliner, nail enamel and mascara; hair cosmetics such as hair treatments, hair liquids and set lotions; and skin external preparations containing various active ingredients. The composition for external use can be applied.

  Among these, in the cosmetics, in particular, makeup cosmetics or sunscreen cosmetics primarily intended to prevent sunburn by actively shielding ultraviolet rays from the sun, the present zinc oxide and / or Or, by including this zinc oxide agglomeration suspension, at least when it is used, it exhibits the shielding effect of ultraviolet rays, especially long wavelength ultraviolet rays, and the excellent transparency to visible light, which are the characteristics of this zinc oxide. Is possible.

  Hereinafter, the present invention will be described more specifically with reference to examples and the like, but the technical scope of the present invention should not be construed as being limited by these examples.

[Production Example] Production of the present zinc oxide An alkali adjusting solution in which sodium carbonate (sodium carbonate decahydrate) and sodium hydroxide were dissolved in 200 ml of water at a molar ratio shown in Table 1 was prepared.

  Separately, 1000 ml of water is put into a reaction vessel, and this is heated to 60 ° C. and maintained at this temperature, while maintaining the pH of the reaction aqueous solution at 8.0 using a pH controller connected to a pump. 1.0M zinc chloride aqueous solution (containing 0.1M hydrochloric acid) and the alkali adjusting solution were added dropwise.

  When a predetermined amount (see Table 1) of an aqueous zinc chloride solution was dropped, the reaction was terminated, and the reaction solution was filtered with a 0.4 μm filter, followed by repeated washing with water three times.

  The residue was dried at 150 ° C. for 12 hours and then calcined at 400 ° C. for 2 hours to obtain each desired zinc oxide aggregate.

  Next, each of the obtained zinc oxide aggregates was dispersed in castor oil at a ratio of 40%, and this was ground with a three-roller (EXAKT: manufactured by Otto Hermann (Germany)), and the oxidation to be tested. Zinc was obtained.

[Test Example 1]
A. Alkaline solution ratio and zinc oxide appearance evaluation Each zinc oxide aggregate obtained in the above production example was magnified 10,000 times or 50000 times with a scanning electron microscope, and its microscopic form was grasped and evaluated. .

Evaluation Criteria O: Zinc oxide units having the following morphological features (1) to (3) aggregate, and the microscopic form of the microscopic appearance is as if it were a carnation flower (FIG. 1: 10000). Double metal structure photograph, Fig. 2: Refer to 50000 times metal structure photograph).
(1) Zinc oxide having an uneven surface with a thickness corresponding to one of these primary particles, in which primary particles of zinc oxide having an average particle diameter of 50 to 100 nm are assembled in a planar shape.
(2) The passing diameter of the zinc oxide described in the above (1) is 0.01 to 5 μm.
(3) Irregular irregularities of 10 to 200 nm are irregularly formed on the edge portion of the zinc oxide surface described in (1) and (2) every 10 to 200 nm.

(Triangle | delta): The rice grain huge particle was recognized (refer FIG. 3: 10,000 times as many metal structure photographs, FIG. 4: 50000 times as many metal structure photographs).

X: Appearance of a card-like appearance (see FIG. 5: 10000-fold metal structure photograph, FIG. 6: 50000-fold metal structure photograph).

  The results are shown in Table 1 (in the table, “-” means unmeasured).

  From this result, in order to obtain the desired carnation flower-like microscopic form of zinc oxide aggregates, the molar ratio of sodium carbonate to sodium hydroxide in the alkali adjustment solution is more than 1: 4 sodium hydroxide. It has been found that the ratio of 1 is preferably 2.5 to 1: 3.5.

B. Relationship between Appearance Evaluation and Light Transmittance of Zinc Oxide Next, visible light (400 nm) transmittance of each of the obtained zinc oxides (obtained by grinding the above zinc oxide aggregates), and UV-A The transmittance of (360 nm) was examined.

  The results are shown in Table 2. [Flower-like zinc oxide] is obtained by arbitrarily sampling zinc oxide obtained by grinding zinc oxide aggregates having a flower-like microscopic form of carnation in the above results. "Curd Zinc Oxide" shows the result of grinding a zinc oxide agglomerate which also has a card-like microscopic morphology, arbitrarily sampled, and "rice granular zinc oxide" Shows the results of a random sample of zinc oxide aggregates, which were also found to have rice-like giant particles.

  Commercial product 1 is ZnO-350 (manufactured by Sumitomo Osaka Cement), and commercial product 2 is FINEX-50 (manufactured by Sakai Chemical).

  Further, as described above, the transmittance at 400 nm and the transmittance at 360 nm were determined by a conventional method [a sample carefully ground with a three-roller was dispersed in a dispersion solvent and further diluted appropriately with oil ( 5-10%), and the transmittance of light of each wavelength in this dispersion was measured].

From this result, the present zinc oxide derived from the carnation flower-like zinc oxide aggregates clearly masks UV-A more efficiently than other zinc oxides and is visible. It has been found that light rays are better transmitted and have better transparency. Further, this aspect of lnT _{360 nm} / lnT _{400 nm} of the zinc oxide: the value of (T _{x nm} X nm transmittance in the transmitted light) have been shown to be 10 or more.

  FIG. 7 is a metallographic photograph (50000 times) of the zinc oxide produced by grinding the carnation flower-like zinc oxide with three rollers as described above, using a scanning electron microscope. . This metal structure photograph revealed that the zinc oxide particles had a form of zinc oxide in which primary particles having an average particle diameter of 50 to 100 nm were assembled in a planar shape.

  FIG. 8 is a chart in which the transmittance of the present zinc oxide and other zinc oxides at each wavelength was confirmed. From this result, the present zinc oxide was superior to the whole ultraviolet rays compared to other zinc oxides. It has been revealed that it has a shielding effect and exhibits excellent transparency to visible light, particularly visible light having a short wavelength.

C. Relationship between calcination temperature and light transmittance In the above production example, the molar ratio of sodium carbonate and sodium hydroxide in the alkaline solution is 3.25 sodium hydroxide with respect to sodium carbonate 1, and the dropping amount of the aqueous zinc chloride solution is is fixed to 1000 ml, the changing the firing temperature resulting zinc oxide aggregate, in the same manner as described above milled lnT optical transparency of the zinc oxide obtained by _{360nm / lnT 400nm (T xnm:} Xnm transmitted light The transmittance was evaluated with The firing was performed until it was recognized that the decarboxylation reaction was sufficiently completed at each temperature.

  The results are shown in Table 3.

In this test system, the firing temperature was around 450 ° C., and lnT _360nm / lnT _400nm was 10.0. When the firing temperature exceeds 450 ° C., zinc oxide particles are sintered, and although the transmittance for visible light is reduced, the shielding property for long-wavelength ultraviolet light is hardly improved, and lnT _{360 nm.} It was revealed that the value of / lnT _400nm would be less than 10.

In addition, when the firing temperature was set to 150 ° C., a high lnT _360nm / lnT _400nm value was obtained, but in the test system 1, the firing times of the test systems 2 and 3 were 1 to 2 hours. It took a whole day to complete the decarboxylation, and it became clear that the production efficiency was inferior.

  When the calcination temperature was less than 150 ° C., it took several days until the decarboxylation reaction was completed, and it became clear that the production efficiency was remarkably inferior.

  In addition, when the zinc oxide obtained at each calcination temperature in this test was subjected to X-ray diffraction, the peak indicating zinc oxide obtained by setting the calcination temperature to a low temperature (150 ° C.) was broad, and this zinc oxide It was shown that the state of is close to amophylls, and the transmittance of visible light was extremely excellent. On the contrary, the peak at a baking temperature of 400 ° C. was relatively sharp, and it became clear that the transmittance of visible light was slightly reduced, but the shielding property of long-wavelength ultraviolet rays was good (the chart is not shown).

  From these results, the zinc oxide having the desired light transmittance (visible light transmittance and long-wavelength ultraviolet light shielding property) is produced by adjusting the firing temperature when preparing the zinc oxide. It was shown that

  Specific formulation examples of the composition for external use (cosmetics) containing the zinc oxide thus obtained are described as examples (both comparative examples), and tests on the composition for external use of these formulations are conducted. went. In addition, all these external compositions were prepared using a conventional method.

  In addition, in the prescriptions of these examples, “the present zinc oxide” is the flower-like zinc oxide produced in the above production example and used in Test Example 1, and “card-like zinc oxide” and “rice granular zinc oxide” Are zinc oxides as defined in Test Example 1, respectively.

[Example 1] O / W cream
Compounding ingredients blending amount (% by weight)
(Water phase)
Purified water remaining 1,3-butylene glycol 7.0
Zinc oxide 5.0
Edetate disodium 0.05
Triethanolamine (99%) 1.0
(Oil phase)
Oxybenzone 2.0
Octyl paramethoxycinnamate 5.0
Squalane 10.0
Vaseline 5.0
Stearyl alcohol 3.0
Stearic acid 3.0
Glyceryl monostearate 3.0
Polyethyl acrylate 1.0
Antioxidant appropriate amount Preservative appropriate amount Fragrance appropriate amount

  In the blending components of Example 1, (1) O / W type cream in which an equal amount of curd-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 1-1, and (2) rice grains instead of the present zinc oxide. O / W type cream containing an equal amount of zinc oxide as Comparative Example 1-2, and (3) O / W type cream containing equal amount of fine particle titanium dioxide instead of the present zinc oxide as Comparative Example 1-3 did.

[Example 2] O / W type emulsion
Compounding ingredients blending amount (% by weight)
(Water phase)
Purified water remaining amount Dipropylene glycol 6.0
Ethanol 3.0
Hydroxyethyl cellulose 0.3
Zinc oxide 5.0
(Oil phase)
Octyl paramethoxycinnamate 6.0
Glyceryl octyl paramethoxycinnamate 2.0
4- tert -Butyl-4'-methoxydibenzoylmethane 2.0
Oxybenzone 3.0
Oleyl oleate 5.0
Dimethylpolysiloxane 3.0
Vaseline 0.5
Cetyl alcohol 1.0
Sorbitan sesquioleate 0.8
Polyoxyethylene (20) oleyl alcohol 1.2
Antioxidant Appropriate amount Preservative Appropriate amount Perfume Appropriate amount

  In the blending components of Example 2, (1) O / W type emulsion containing equal amount of card-like zinc oxide instead of the present zinc oxide was used as Comparative Example 2-1, and (2) rice grains instead of the present zinc oxide. O / W type emulsion containing equal amount of zinc oxide as Comparative Example 2-2, and (3) O / W type emulsion containing equal amount of fine particle titanium dioxide instead of the present zinc oxide as Comparative Example 2-3 did.

[Example 3] W / O type cream
Compounding ingredients blending amount (% by weight)
(Water phase)
Purified water remaining 1,3-butylene glycol 10.0
(Oil phase)
Zinc oxide (hydrophobized) 20.0
Squalane 20.0
Glycerin diisostearate 5.0
Organically modified montmorillonite 3.0
Preservative Appropriate amount Fragrance Appropriate amount

  In this blending component of Example 3, (1) a W / O cream containing equal amounts of hydrophobized card-like zinc oxide instead of the present zinc oxide was referred to as Comparative Example 3-1, and (2) the present zinc oxide. Instead of this, W / O type cream containing equal amounts of hydrophobized rice granular zinc oxide was used as Comparative Example 3-2. (3) Commercially available product of zinc oxide hydrophobized in place of zinc oxide [FINEX -50 (manufactured by Sakai Chemical Co., Ltd.)] was used as Comparative Example 3-3.

[Example 4] Oil type cosmetic
Compounding ingredients blending amount (% by weight)
This zinc oxide 10.0
Liquid paraffin 60.0
Cetyloctanoate 28.0
Antioxidant Appropriate amount Perfume Appropriate amount

  In the blending component of this Example 4, (1) oil type cosmetics containing equal amounts of card-like zinc oxide in place of the present zinc oxide is referred to as Comparative Example 4-1, and (2) rice granules in place of the present zinc oxide. An oil type cosmetic containing an equal amount of zinc oxide is referred to as Comparative Example 4-2, and (3) an oil type containing an equivalent amount of a commercially available zinc oxide [FINEX-50 (manufactured by Sakai Chemical)] instead of the present zinc oxide. The cosmetic was designated as Comparative Example 4-3.

[Example 5] Oil type cosmetic
Compounding ingredients blending amount (% by weight)
This zinc oxide (hydrophobized) 10.0
Liquid paraffin 48.0
Isopropyl myristate 10.0
Silicone oil 30.0
Silicone resin 2.0
Antioxidant Appropriate amount Perfume Appropriate amount

  In this blending component of Example 5, (1) an oil-type cosmetic containing an equal amount of hydrophobized card-like zinc oxide instead of the present zinc oxide is referred to as Comparative Example 5-1, and (2) the present zinc oxide Instead, an oil-type cosmetic containing an equal amount of hydrophobized rice granular zinc oxide was used as Comparative Example 5-2, and (3) a commercial product of hydrophobized zinc oxide instead of the present zinc oxide [FINEX-50 An oil-type cosmetic containing an equal amount (made by Sakai Chemical Co., Ltd.) was designated as Comparative Example 5-3.

[Example 6] Gel
Compounding ingredients blending amount (% by weight)
This zinc oxide 10.0
Liquid paraffin 60.0
Olive oil 20.0
Organically modified montmorillonite 5.0
BHT (antioxidant) appropriate amount perfume appropriate amount

  In the blending component of this Example 6, (1) Gel in which an equal amount of curd-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 6-1, and (2) Rice granular zinc oxide was replaced with the present zinc oxide. An equal amount blended gel was referred to as Comparative Example 6-2, and (3) a zinc oxide commercial product [FINEX-50 (manufactured by Sakai Chemical Co.)] instead of the present zinc oxide was blended in an equal amount with Comparative Example 6-3. did.

[Example 7] Lotion
Compounding ingredients blending amount (% by weight)
Purified water remaining amount Zinc oxide 5.0
Dipropylene glycol 5.0
1,3-butylene glycol 10.0
Polyethylene glycol 400 10.0
Ethyl alcohol 20.0
Polyoxyethylene (60) hydrogenated castor oil 3.0
Octyl paramethoxycinnamate 1.0
Perfume appropriate amount

  In the blending components of Example 7, (1) a lotion in which an equal amount of card-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 7-1, and (2) rice granular zinc oxide was replaced with the present zinc oxide. A lotion containing an equal amount of Comparative Example 7-2 was used, and (3) a lotion containing an equal amount of a commercial product of zinc oxide [FINEX-50 (manufactured by Sakai Chemical)] instead of the present zinc oxide was compared with Comparative Example 7-3. did.

[Example 8] Dual-use foundation
Compounding ingredients blending amount (% by weight)
Silicone-treated talc 19.2
Silicone-treated mica 40.0
Zinc oxide (hydrophobized) 5.0
Silicone-treated titanium dioxide 15.0
Silicone-treated red iron oxide 1.0
Silicone-treated yellow iron oxide 3.0
Silicone-treated black iron oxide 0.2
Zinc stearate 0.1
Nylon powder 2.0
Squalane 4.0
Solid paraffin 0.5
Dimethylpolysiloxane 4.0
Glycerin triisooctanoate 5.0
Octyl methoxycinnamate 1.0
Antiseptic appropriate amount Antioxidant appropriate amount Fragrance appropriate amount

  In the blending components of this Example 8, (1) a dual-use foundation in which an equal amount of hydrophobized card-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 8-1, and (2) the present zinc oxide was replaced. A dual-use foundation containing equal amounts of hydrophobized rice granular zinc oxide was used as Comparative Example 8-2, and (3) a hydrophobized zinc oxide commercial product [FINEX-50 (manufactured by Sakai Chemical Co., Ltd.) instead of this zinc oxide. )] Was blended in equal amounts to make a comparative example 8-3.

[Example 9] Cake type foundation
Compounding ingredients blending amount (% by weight)
Talc 36.9
Kaolin 15.0
Sericite 10.0
Zinc flower 7.0
This zinc oxide 10.0
Red iron oxide 1.0
Yellow iron oxide 2.9
Black iron oxide 0.2
Squalane 8.0
Monooleic acid POE sorbitan 3.0
Isocetyl octoate 2.0
Isostearic acid 4.0
Preservative Appropriate amount Antioxidant Appropriate amount Fragrance Appropriate amount

  In the blending components of Example 9, (1) a cake type foundation in which an equal amount of curd-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 9-1, and (2) rice granular oxide was substituted for the present zinc oxide. A cake type foundation containing an equal amount of zinc was used as Comparative Example 9-2, and (3) a cake type foundation containing an equivalent amount of a commercial product of zinc oxide [FINEX-50 (manufactured by Sakai Chemical)] instead of this zinc oxide was used. It was set as Comparative Example 9-3.

[Example 10] O / W emulsion type foundation (liquid type)
Compounding ingredients blending amount (% by weight)
Talc 3.0
Zinc oxide 15.0
Red iron oxide 0.5
Yellow iron oxide 1.4
Black iron oxide 0.1
Bentonite 0.5
Polyoxyethylene sorbitan monostearate 0.9
Triethanolamine 1.0
Propylene glycol 10.0
Purified water Residual amount Stearic acid 2.2
Isohexadecyl alcohol 7.0
Glycerol monostearate 2.0
Liquid lanolin 2.0
Liquid paraffin 2.0
Preservative Appropriate amount Fragrance Appropriate amount

  In the blending components of Example 10, (1) O / W emulsified foundation (liquid type) in which an equal amount of card-like zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 10-1, and (2) the present oxidation. An O / W emulsion type foundation (liquid type) containing equal amounts of rice granular zinc oxide instead of zinc was used as Comparative Example 10-2, and (3) a commercial product of zinc oxide [FINEX-50 ( An O / W emulsified foundation (liquid type) containing an equal amount of Sakai Chemical Co., Ltd.) was designated as Comparative Example 10-3.

[Example 11] O / W emulsified foundation (cream type)
Compounding ingredients blending amount (% by weight)
Hydrophobized sericite 5.36
Hydrophobized kaolin 4.0
This zinc oxide (hydrophobized) 9.32
Hydrophobized red iron oxide 0.36
Hydrophobized yellow iron oxide 0.8
Hydrophobized black iron oxide 0.16
Liquid paraffin 5.0
Decamethylcyclopentasiloxane 12.0
Polyoxyethylene-modified dimethylpolysiloxane 4.0
Purified water residual amount dispersant 0.1
1,3-butylene glycol 5.0
Preservative appropriate amount stabilizer 2.0
Perfume appropriate amount

  In the blending component of this Example 11, (1) an O / W emulsified foundation (cream type) in which an equal amount of hydrophobized card-like zinc oxide was blended in place of the present zinc oxide was referred to as Comparative Example 11-1. 2) O / W emulsified foundation (cream type) containing equal amounts of hydrophobized rice granular zinc oxide in place of the present zinc oxide was designated as Comparative Example 11-2, and (3) hydrophobized in place of the present zinc oxide. Comparative Example 11-3 was an O / W emulsified foundation (cream type) containing an equal amount of a commercially available zinc oxide product [FINEX-50 (manufactured by Sakai Chemical)].

[Example 12] W / O emulsion type foundation (two-layer dispersion type)
Compounding ingredients blending amount (% by weight)
Hydrophobic talc 7.0
Zinc oxide (hydrophobized) 12.0
Silica anhydride 2.0
Nylon powder 4.0
Color pigment 2.0
Octamethylcyclotetrasiloxane 10.0
Rosin acid pentaerythritz 1.5
Neopentyl glycol diisooctanoate 5.0
Squalane 2.5
Glycerin triisooctanoate 2.0
Polyoxymethylene-modified dimethylpolysiloxane 1.5
Purified water remaining 1,3-butylene glycol 4.0
Ethanol 7.0

  In this blending component of Example 12, (1) a W / O emulsified foundation (two-layer dispersion type) in which an equal amount of hydrophobized card-like zinc oxide was blended instead of the present zinc oxide was defined as Comparative Example 12-1. (2) A W / O emulsified foundation (two-layer dispersion type) containing equal amounts of hydrophobized rice granular zinc oxide in place of the present zinc oxide is referred to as Comparative Example 12-2, and (3) the present zinc oxide Instead, a W / O emulsified foundation (two-layer dispersion type) containing an equal amount of a commercially available zinc oxide commercial product [FINEX-50 (manufactured by Sakai Chemical)] was used as Comparative Example 12-3.

[Example 13] Powdery foundation
Compounding ingredients blending amount (% by weight)
Talc 20.3
Mica 30.0
Kaolin 5.0
This zinc oxide 10.0
Titanium dioxide 5.0
Zinc stearate 1.0
Red iron oxide 1.0
Yellow iron oxide 3.0
Black iron oxide 0.2
Nylon powder 10.0
Squalane 6.0
Lanolin acetate 1.0
Octyldodecyl myristate 2.0
Diisooctanoic acid neopentyl glycol 2.0
Sorbitan monooleate 0.5
Preservative Appropriate amount Fragrance Appropriate amount

  In the blending component of Example 13, (1) a powdery foundation in which an equal amount of curd zinc oxide was blended instead of the present zinc oxide was used as Comparative Example 13-1, and (2) rice granular zinc oxide was substituted for the present zinc oxide. Comparative Example 13-2 is a powdery foundation containing equal amounts of (3), and (3) a powdery foundation containing equal amounts of a commercial product of zinc oxide [FINEX-50 (manufactured by Sakai Chemical)] instead of the present zinc oxide is Comparative Example 13. -3.

[Test Example 2] Evaluation of composition for external use (cosmetics) Evaluation by lnT _360nm / lnT _400nm Each cosmetic was formed on a quartz plate to a thickness of 5 μm. Using this as a measurement sample, using a spectrophotometer (with Hitachi UV3410 integrating sphere), transmittance at λ = 360 nm as an evaluation index of long-wavelength ultraviolet shielding property, and at λ = 400 nm as an evaluation index of transmittance for visible light The transmittance was measured. Based on these, lnT _360nm / lnT _400nm was calculated, and Examples 1 to 7 (including comparative examples related thereto) were evaluated.

Evaluation criteria ○: When lnT _360nm / lnT _400nm is 10 or more Δ: When lnT _360nm / lnT _400nm is less than 10 or more than 8 ×: When lnT _360nm / lnT _400nm is less than 8 The results of this test are shown in Table 4 .

As is apparent from Table 4, the cosmetics formulated with this zinc oxide, regardless of whether or not they have been hydrophobized, each have an lnT _360nm / InT _400nm of 10 or more, but each comparison All examples were less than 10.

  That is, it has been clarified that the cosmetic containing the present zinc oxide satisfies desired properties in terms of transparency to visible light and shielding properties against long-wavelength ultraviolet rays.

B. Evaluation by transmittance at λ = 360 nm For cosmetics of Examples 8 to 13 (including comparative examples related thereto), only the transmittance at λ = 360 nm related to long wavelength ultraviolet shielding was used as an evaluation index ( The measurement method is the same as A above).

Evaluation criteria ○: When T _{360 nm} is less than 30% Δ: When T _{360 nm} is 30% or more and less than 40% x: When T _{360 nm} is 40% or more The results of this test are shown in Table 5.

  As is apparent from Table 5, the cosmetics blended with the present zinc oxide were all evaluated to be equal to or better than the best in the comparative examples in terms of long-wavelength ultraviolet shielding properties.

  That is, this zinc oxide has a long wavelength equivalent to or longer than that of the conventional zinc oxide that has the best long-wavelength ultraviolet shielding effect even when blended in a foundation that does not directly cause visible light transmittance. It became clear that it showed an ultraviolet shielding effect.

It is drawing which showed the metal structure photograph in the magnification of 10000 time of this zinc oxide aggregate. It is drawing which showed the metal structure photograph in the magnification of 50000 times of this zinc oxide aggregate. It is drawing which showed the metal structure photograph in the magnification of 10000 times of the zinc oxide aggregate in which the rice granular giant particle is recognized. It is drawing which showed the metal structure photograph in the magnification of 50000 times of the zinc oxide aggregate by which a rice granular giant particle is recognized. It is drawing which showed the metal structure photograph in the magnification of 10000 times of the zinc oxide aggregate in which card-like appearance is recognized. It is drawing which showed the metal structure photograph in the magnification of 50000 times of the zinc oxide aggregate in which card-like appearance is recognized. It is drawing which showed the metal structure photograph in the magnification of 50000 times of this zinc oxide. It is the chart which confirmed the transmittance | permeability of this zinc oxide and another zinc oxide in each wavelength.

Claims (6)

Using water as a reaction solvent, zinc ions (Zn ²⁺ ), carbonate ions (CO ₃ ²⁻ ), and hydroxide ions (OH ⁻ ) are maintained at a pH of 7-9 in the reaction aqueous solution, and carbonate ions of the hydroxide ions. Produced by calcining basic zinc carbonate formed in this reaction aqueous solution by reacting with a molar ratio of ions set to 4 or less (excluding 0) for hydroxide ions to carbonate ions 1. A method for producing a zinc oxide aggregate characterized by the above. 2. The zinc oxide aggregate according to claim 1, wherein the molar ratio of hydroxide ion to carbonate ion is 2.5 to 3.5 with respect to carbonate ion 1. Manufacturing method. In the above production method, (1) the zinc ion donating substance in the reaction aqueous solution is zinc chloride, zinc sulfate or zinc nitrate, (2) the carbonate ion donating substance is sodium carbonate or potassium carbonate, and ( 3) The method for producing a zinc oxide aggregate according to claim 1 or 2, wherein the hydroxide ion donating substance is sodium hydroxide or potassium hydroxide. In the said manufacturing method, the temperature of reaction aqueous solution is 40 to 70 degreeC, The manufacturing method of the zinc oxide aggregate in any one of Claims 1-3 characterized by the above-mentioned. In the said manufacturing method, the calcination temperature of basic zinc carbonate is 150 to 450 degreeC, The manufacturing method of the zinc oxide aggregate in any one of Claims 1-4 characterized by the above-mentioned. A method for producing zinc oxide, comprising pulverizing a zinc oxide aggregate produced by the production method according to claim 1.