JP2000086210A - Boron nitride-oxide composite particles, their production and ultraviolet ray cut-off agent using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain boron nitride-oxide composite particles and boron nitride- multiple oxide composite particles excellent in dispersibility, lubricative property, transparency, weather resistance, heat resistance and UV cut-off property. SOLUTION: An oxide, a multiple oxide or a mixture of these is dispersed in an aq.soln. or alcoholic soln. contg. dissolved boric acid and urea, the solvent is evaporated and the resultant precursor is heated in a nonoxidizing atmosphere to obtain the objective boron nitride-oxide composite particles or boron nitride- multiple oxide composite particles excellent in dispersibility, lubricative property, transparency, weather resistance, heat resistance and UV cut-off property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to boron nitride / oxide composite particles excellent in dispersibility, lubricity (slipperiness), transparency, weather resistance, heat resistance, and ultraviolet blocking properties, and a method for producing the same.
And an ultraviolet blocking agent using the same.

[0002]

2. Description of the Related Art Ultraviolet rays not only degrade organic materials such as plastics, but also have a strong adverse effect on living organisms. Ultraviolet rays in the UV-B region having a wavelength of 280 to 320 nm cause inflammation of the skin. 320-400
Ultraviolet light in the UV-A range of nm is known to brown the skin. As one of the prevention methods, various organic ultraviolet absorbers and inorganic ultraviolet scattering agents have been developed.

[0003] Organic UV absorbers have been widely used because they are colorless and transparent when incorporated into plastics and cosmetics. However, in recent years, safety due to lack of heat resistance and weather resistance and toxicity of decomposition products have been reported. There are many problems in terms of use and use is restricted. On the other hand, titanium oxide, which is an inorganic ultraviolet scattering agent, shows an effective ultraviolet shielding effect against ultraviolet rays in the UV-B region, but has almost no effect on ultraviolet rays in the UV-A region, and has a cosmetic effect. However, they often have a pale tint when blended into the ingredients. Conversely, although zinc oxide has high transparency, it has a problem that its blocking effect on ultraviolet rays in the UV-B region is not sufficient.

[0004] In order to solve the above-mentioned problems, various types of inorganic ultraviolet blocking agents have been devised. For example,
JP-A-1-190626, JP-A-5-330825
As described in Japanese Patent Application Laid-Open No. 9-45528, a technique of coating or compounding the surface of titanium oxide with various oxides is known. The use feeling and safety were insufficient, such as irritation to the skin.

Recently, Japanese Patent Application Laid-Open No. 6-145645 has disclosed
JP-A-7-207251, JP-A-9-11861
As can be seen in No. 0, techniques utilizing a cerium compound as an ultraviolet blocking agent have been developed, but with these methods, although the ultraviolet blocking ability and the dispersibility of the particles are improved,
There was a problem that the obtained powder exhibited pale yellow or yellow.

[0006]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide dispersibility, lubricity, transparency, weather resistance, heat resistance, and ultraviolet ray blocking properties which could not be achieved by the conventional techniques and manufacturing methods. An object of the present invention is to provide an excellent boron nitride / oxide composite particle, a method for producing the same, and an ultraviolet ray blocking agent using the same.

[0007]

Means for Solving the Problems and Actions / Effects In order to solve the above-mentioned problems, the boron nitride-oxide composite particles of the present invention can be used as an oxide, a composite oxide, or a mixture thereof, in an amorphous or crystalline form. It is characterized by compounding a conductive boron nitride. According to this configuration, since they are a combination of mutually chemically stable substances, composite particles having excellent weather resistance and heat resistance can be obtained. For example, they are suitably used as ultraviolet absorbers even in applications exposed to severe environments. it can.

[0008] The composite particles have a structure in which the surfaces of oxide particles made of an oxide, a composite oxide, or a mixture thereof are coated with boron nitride. By coating the surface of the oxide particles with boron nitride, lubricity and dispersibility are improved, and further, there is an effect of suppressing or suppressing the catalytic activity.

The proportion of boron nitride in the above composite particles can be set arbitrarily. However, when the volume fraction of boron nitride in the obtained composite particles is adjusted to be 1 to 60% by volume, lubrication becomes smooth. This has the effect that the effect of suppressing the properties, ultraviolet blocking properties and catalytic activity is further increased.

Further, the ultraviolet blocking agent of the present invention comprises an oxide,
It is characterized in that the composite oxide or a mixture thereof contains boron nitride / oxide composite particles in which amorphous and / or crystalline boron nitride is composited. The boron nitride of the present invention
By applying the oxide composite particles as an ultraviolet ray blocking agent,
UV-B to UV without compromising the transparency of the visible region
-It shows an excellent ultraviolet blocking effect over almost the entire region of -A region, and has high stability and safety because the catalytic activity is suppressed.

The boron nitride / oxide composite particles of the present invention
The surface of the oxide particles made of an oxide, a composite oxide, or a mixture thereof may be coated with boron nitride. Thereby, there is an effect that the raw material is very inexpensive, and an effect that only the oxide is immersed in the solution and heat treatment is performed, and the production is easy.

The above-mentioned composite particles can be configured to cover the surface of the oxide particles with amorphous boron nitride. Here, the amorphous boron nitride in the present invention means boron nitride having an amorphous and / or turbostratic structure. By making the boron nitride layer amorphous, there is an effect that the heat treatment temperature at the time of manufacturing can be lowered.

Next, the average particle size of the composite particles is not particularly limited, but is, for example, 0.001 μm to 50 μm.
It can be adjusted to 0 μm. For example, 0.001 μm
By selecting the above particle size, handling and synthesis become easy, and therefore it is more preferable. On the other hand, by selecting a particle size of 500 μm or less, it is possible to suppress deterioration of dispersibility and roughness when blended in plastics or cosmetics as an ultraviolet blocking agent.

The type of oxide used is not particularly limited. For example, solid oxides of typical elements, amphoteric elements, transition metal elements, rare earth elements, and actinoids, preferably barium oxide, calcium oxide, strontium oxide, silicon oxide, Aluminum oxide, magnesium oxide, iron oxide,
Copper oxide, silver oxide, nickel oxide, palladium oxide, cobalt oxide, titanium oxide, zinc oxide, molybdenum oxide, tungsten oxide, zirconium oxide, hafnium oxide,
Vanadium oxide, niobium oxide, tantalum oxide, scandium oxide, yttrium oxide, and lanthanum oxide,
One or more of the oxides of the rare earth elements having atomic numbers 57 to 71, including cerium oxide, and a composite oxide containing at least one of the above-mentioned elements or a mixture thereof can be used. In particular, if an oxide selected from cerium oxide, titanium oxide, zinc oxide and zirconium oxide is used, there is an advantage that the ultraviolet ray blocking effect is large.

The composite particles of the present invention as described above can be easily produced by the following production method of the present invention. That is,
After dispersing the oxide, composite oxide or a mixture thereof in an aqueous solution or an alcohol solution in which boric acid and urea are dissolved, the solvent is evaporated and dried to form a precursor, and the precursor is placed in a non-oxidizing atmosphere. By heating, boron nitride / oxide composite particles are obtained. Hereinafter, the present invention will be described in more detail.

By the operation and manufacturing process shown in FIG. 1, various oxides including transition metal oxides and rare earth oxides, and composite particles of a composite oxide and boron nitride can be manufactured.

In the method for producing boron nitride / oxide composite particles of the present invention, various oxides, composite oxides, or a mixture thereof are dispersed in an aqueous solution in which boric acid and urea are dissolved or in an alcohol solution. The method is characterized in that the solvent is evaporated and the obtained precursor is heated in a non-oxidizing atmosphere.

In order to produce the boron nitride / oxide composite particles of the present invention, it is necessary to produce various oxides and composite oxides.

The oxides and composite oxides used as starting materials in the present invention include precipitation, coprecipitation, uniform precipitation, hydrothermal synthesis, hydrolysis, chemical vapor transport,
Various oxides, composite oxides, and oxide particles (including fine particles and ultrafine particles) prepared by a thermal decomposition method, a spray drying method, a sputtering method, a gas evaporation method, a microemulsion method, an emulsion method, a laser synthesis method, and the like. The same applies hereinafter), composite oxide particles, or mixtures thereof, commercially available oxides, composite oxides, oxide particles, composite oxide fine particles, or mixtures thereof, or commercially available hydroxides, oxalates, Of carbonates, acetates, citrates, nitrates, chlorides, sulfates, alkoxides, acetylacetonato complexes, various organometallic compounds, oxides obtained by calcining, composite oxides or mixtures thereof, Any of these may be used, but preferably, in order to enhance the dispersibility and eliminate the feel of the particle size, regardless of the preparation or commercial product, oxide fine particles having a particle size of 10 μm or less. Composite oxide fine particles is used.

The form of the primary particles and the secondary particles constituting the oxide and composite oxide particles used in the present invention is not particularly limited, and may be spherical, acicular, columnar, polyhedral, porous, hollow, or hollow. These aggregates and the like can be used by changing the form of the particles according to the application. For example, when used in paints and cosmetics, it is desirable to use hollow particles because of their low apparent specific gravity and high dispersibility.

The average particle diameter of the boron nitride / oxide composite particles obtained in the present invention is 0.001 μm to 500 μm depending on the average particle diameter of the oxide or composite oxide used and the thickness of the boron nitride layer to be composited. Can be adjusted to the range. For example, when used as fine particles for cosmetics, it is desirable to make the average particle diameter 0.05 μm or less from the viewpoint of increasing the transparency in the visible region.

In the present invention, the amount of boron nitride to be composited can be controlled at an arbitrary ratio to the oxide powder to be composited by changing the mixing ratio of the raw materials, the reaction temperature and the reaction time. Although not particularly limited, it is desirable to adjust so that the volume fraction of boron nitride in the obtained composite particles is 1 to 60%. The reason is that by selecting a volume fraction of 60% or more, it becomes difficult to obtain a high ultraviolet blocking effect, and on the other hand, by selecting a volume fraction of 1% or less, suppression of catalytic activity and lubricity can be achieved. This is because it becomes difficult to improve the quality.

When the surface of the oxide or composite oxide is coated with boron nitride in the present invention, the thickness of the boron nitride layer may be from several nm to several nm depending on the reaction temperature, reaction time, type of oxide to be coated, and the like. It changes in the range of 10 nm. This is not particularly limited, but is preferably adjusted to 1 to 20 nm in order to simultaneously achieve a high ultraviolet blocking effect, suppression of catalytic activity, and excellent lubricity.

In the present invention, water or alcohol can be used as a solvent. When an alcohol is used, any alcohol having 1 or more carbon atoms may be used, but preferably, methanol or ethanol which is inexpensive and easily available is used.

In the present invention, as the raw material of the boron nitride to be composited, any material can be used as long as it is a nitrogen- or boron-containing compound dissolved in a solvent of water or alcohol, but boric acid and urea are preferably used. In this case, the ratio of boric acid and urea to be dissolved in the solvent can be arbitrarily set. However, in order to increase the production yield of boron nitride, the stoichiometric ratio of boron nitride is preferably 1: 1. The amount of urea is excessively increased to about twice the amount of boric acid based on the ratio of

In the present invention, the precursor composed of boric acid, urea and oxide particles is obtained by dissolving boric acid and urea in water or alcohol as a solvent and dispersing the oxide particles in the solution. Obtained by evaporating the solvent. Evaporation of the solvent may be performed by using a thermostatic drier, a rotary evaporator, or the like, in addition to natural evaporation and heat evaporation. In addition, an ultrasonic dispersing device is used for dispersing the oxide particles, but in addition, a stirrer such as a magnetic stirrer or a homogenizer may be used.

The precursor particles produced in the present invention are subjected to a reduction treatment in a non-oxidizing or inert gas atmosphere such as nitrogen, hydrogen, ammonia, argon, helium or the like or in a vacuum, and boron nitride is converted from unreacted boric acid and urea to boron nitride. Is generated. At this time, the oxygen partial pressure is 0.01% of the total gas pressure.
% Is desirable. The processing temperature at this time is 20
Although it can be carried out at any temperature in the range of 0 to 1500 ° C., it is desirable to carry out at 200 to 700 ° C. in order to suppress the aggregation of particles. At a temperature of 200 ° C. or lower, the efficiency of boron nitride formation is remarkably reduced due to a decrease in the reaction rate.
If the temperature is higher than 500 ° C., sintering and grain growth occur between the particles, and the dispersibility and the transparency are reduced. The particles after the treatment are washed with water, hydrocarbon, alcohol, acetone, petroleum ether or the like. The washing means may be a centrifugal separation, filtration and decantation, or a fine powder washing apparatus using a ceramic filter or an ultrafiltration membrane. The washed particles are dried by natural drying at room temperature or by heating and drying using an oven or the like. At this time, a vacuum dryer or a spray dryer may be used.

In this way, to obtain boron nitride / oxide composite particles and / or boron nitride / composite oxide composite particles having excellent dispersibility, lubricity, transparency, weather resistance, heat resistance, and ultraviolet blocking properties. However, in the production method of the present invention, the boron nitride-oxide composite particles or the boron nitride-composite oxide composite particles obtained by the drying may be fired as necessary. This calcination is particularly effective when oxide particles that are easily reduced are used, and the oxide reduced by the heat treatment in a non-oxidizing atmosphere returns to the original state. The firing temperature at this time is 150 to 1000 ° C., preferably 300 ° C.
To 600 ° C., the heating rate is 500 ° C./hour or less, preferably 100 ° C./hour, and the firing time is 30 minutes to 12 hours, preferably 1 to 3 hours. Firing temperature,
It can be said that it is desirable to set the upper limit and the lower limit of the firing time and the heating time so that reoxidation is not insufficient in any case, and aggregation, grain growth, and sintering due to the firing process are not likely to occur. .

Next, a plastic using the boron nitride / oxide composite particles and / or the boron nitride / composite oxide composite particles obtained by the present invention as an ultraviolet shielding material will be described. In general, it is known that plastics deteriorate when absorbing ultraviolet rays contained in sunlight. As a countermeasure, the photodeterioration can be prevented or reduced by blending the boron nitride / oxide composite particles or the boron nitride / composite oxide composite particles of the present invention.

The plastic mentioned here includes a synthetic resin such as polyvinyl chloride, polycarbonate, and polypropylene, a natural resin, and a paint containing at least one of them.

Also, boron nitride / oxide composite particles and / or
Alternatively, the mixing ratio of the boron nitride / composite oxide composite particles to the plastic can be arbitrarily set, but is preferably adjusted to a range of 0.5 to 50% by weight. If the compounding ratio is less than 0.5% by weight, it is too small to obtain a sufficient ultraviolet ray blocking effect, while if it is more than 50% by weight, the dispersibility decreases. Further, an additive such as a dispersant may be added at the time of compounding.

Next, a cosmetic using the boron nitride / oxide composite particles and / or boron nitride / composite oxide composite particles obtained by the present invention as an ultraviolet ray blocking material will be described.
The cosmetic containing the boron nitride-oxide composite particles or the boron nitride-oxide composite particles of the present invention has high transparency and exhibits an excellent ultraviolet light shielding effect. The cosmetic formulation can be used in foundations, lipsticks, eye shadows, emulsions, creams, lotions, hair cosmetics, and the like, and is preferably used as a sunscreen cosmetic. The mixing ratio is not particularly limited, but is preferably adjusted to 0.1 to 70% by weight. If the compounding ratio is 0.5% by weight or less, it may be difficult to obtain a sufficient ultraviolet ray blocking effect, while
If the content is 70% by weight or more, the dispersibility and the transparency may be reduced.

When used as a cosmetic, boron nitride-oxide composite particles and / or boron nitride-oxide composite particles further subjected to a surface treatment may be used. Examples of the surface treatment include amino acid treatment, collagen treatment, lecithin treatment, triglyceride treatment, silicone treatment, metal soap treatment, and chitin / chitosan treatment.

The boron nitride obtained by the present invention
In cosmetics using the oxide composite particles and / or the boron nitride / composite oxide composite particles as an ultraviolet shielding material, other ultraviolet absorbers and ultraviolet scattering agents are used within a range that does not cause problems caused by the use thereof. It may be added. Benzophenone, salicylic acid, PABA
, Dibenzoylmethane, cinnamate, etc., and at least one kind of UV scattering agent is preferably titanium oxide, zinc oxide, cerium oxide, or the like, and more preferably 50 or more.
at least one of titanium oxide, zinc oxide, and cerium oxide having a size of at most nm.

Further, when the boron nitride / oxide composite particles and / or boron nitride / composite oxide composite particles of the present invention are used in cosmetics as an ultraviolet ray blocking material, a dispersant, a surfactant, an oil agent, a gelling agent, Additives such as polymers, humectants, cosmetic ingredients, pigments, preservatives, powders, and fragrances can be used within a range that does not impair the effects of the present invention.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 200 ml of 1 mol / l cerium nitrate aqueous solution and 200 ml of 3 mol / l ammonia water were prepared. Both were simultaneously charged into a 1 liter container and mixed with stirring. The pH of this solution was about 11. After stirring for 2 hours, decantation and water washing were repeated, dried at 120 ° C., and calcined at 500 ° C. for 1 hour to obtain a cerium oxide powder.

Next, boric acid which theoretically becomes 50% by volume of boron nitride with respect to the obtained cerium oxide,
An ethanol solution in which twice the amount of urea was dissolved was prepared, and the above-mentioned cerium oxide powder was added thereto. After dispersion by an ultrasonic disperser for 12 hours, 100 ml of deionized water was added, and drying was performed using a rotary evaporator. went.
Thereafter, the resulting dry powder was pulverized, dried in a dryer at 80 ° C. for 7 days, and then subjected to a reduction nitriding treatment in nitrogen at 500 ° C. for 10 hours. The obtained powder was washed three times with deionized water and then dried at 120 ° C. in air.

The powder obtained by calcining the boron nitride / cerium oxide composite particles thus obtained at 400 ° C. for 3 hours was almost white. FIG. 2 shows the result of X-ray diffraction. In addition to the diffraction pattern of cerium oxide, 2θ = 20-
At 25 °, a peak specific to boron nitride having a turbostratic structure was observed. High-resolution TEM observation of the obtained boron nitride / cerium oxide composite particles showed that the surface of the cerium oxide particles was covered with another layer having a turbostratic structure. The particle surface was qualitatively and quantitatively analyzed by XPS measurement. As a result, the surface of the cerium oxide was covered with boron nitride, and the surface composition was 3% of cerium oxide and 97% of boron nitride.

FIG. 3 shows the results of measuring the light reflectance of the boron nitride / cerium oxide composite particles. From this figure, it can be seen that the boron nitride / oxide composite particles of the present invention have excellent blocking ability in the ultraviolet region. It is clear that
Therefore, the production method of the present invention is also useful for producing an ultraviolet ray blocking agent. Furthermore, the boron-cerium oxide composite particles obtained in the present invention did not undergo strong aggregation, and were extremely excellent in dispersibility.

FIG. 4 shows the results of measuring the light transmittance of the above-mentioned boron nitride / cerium oxide composite particles and various inorganic ultraviolet blocking agents, wherein A is the boron nitride / cerium oxide composite particles, and B is the fine particle oxidized particles. Titanium and C are particulate zinc oxide. Castor oil 2.0 g for each inorganic UV-blocker
And 10.0 g of a clear lacquer were mixed with each other so that the transmittance at 390 nm was equal, and this solution was applied to a transparent quartz plate to a thickness of 40 μm, and was measured by a spectrophotometer (UV-2200 manufactured by Shimadzu Corporation). It was measured. FIG. 4 shows that the boron nitride / cerium oxide composite particles of the present invention had higher transparency in the visible region than other inorganic ultraviolet blocking agents.

Example 2 The same procedure as in Example 1 was carried out except that the amount of boric acid added was changed to 20% by volume of boron nitride. As a result, boron nitride was 76% with respect to cerium oxide 24%, and cerium oxide fine particles whose surface was covered with boron nitride were obtained although the amount of boron nitride was smaller than that in Example 1.

Example 3 The same procedure as in Example 1 was carried out except that a commercially available titanium oxide powder was used as the oxide. As a result, titanium oxide fine particles whose surface was covered with boron nitride were obtained.

Example 4 The same procedure as in Example 1 was carried out except that a commercially available zinc oxide powder was used as the oxide. As a result, zinc oxide fine particles whose surface was coated with boron nitride were obtained.

Example 5 A cerium nitrate aqueous solution was changed to a mixed aqueous solution of cerium nitrate and zirconyl nitrate.
Performed in the same manner as in Example 1. As a result, cerium oxide-zirconium oxide composite oxide particles whose surfaces were covered with boron nitride were obtained.

[0046]

The boron nitride / oxide composite particles of the present invention,
And boron nitride / composite oxide composite particles are excellent in dispersibility, lubricity, transparency, weather resistance, heat resistance, and ultraviolet ray blocking properties, so that paints, pigments, cosmetics, phosphor materials, ceramic materials It is useful as a catalyst, an optical material, and an ultraviolet ray blocking agent.

[Brief description of the drawings]

FIG. 1 is a process chart for producing boron nitride / oxide composite particles and boron nitride / composite oxide composite particles according to the present invention.

FIG. 2 is an X-ray diffraction diagram of the boron nitride / cerium oxide composite particles produced in Example 1.

FIG. 3 is a curve diagram showing an ultraviolet blocking effect of the boron nitride / cerium oxide composite particles produced in Example 1.

FIG. 4 is a curve diagram showing the transparency of the boron nitride / cerium oxide composite particles produced in Example 1.

Claims (7)

[Claims] 1. A boron nitride-oxide composite particle obtained by compounding amorphous and / or crystalline boron nitride with an oxide, a composite oxide or a mixture thereof. 2. The boron nitride / oxide composite particles according to claim 1, wherein the surfaces of the oxide particles comprising an oxide, a composite oxide, or a mixture thereof are coated with boron nitride. 3. The boron nitride-oxide composite particles according to claim 2, wherein the surface of the oxide particles is covered with amorphous and / or crystalline boron nitride. 4. The boron nitride / oxide composite particles according to claim 1, wherein the average particle diameter is adjusted to 1 nm to 500 μm. 5. The boron nitride / oxide composite particles according to claim 1, wherein the oxide is selected from the group consisting of cerium oxide, titanium oxide, zinc oxide and zirconium oxide. 6. An oxide, a composite oxide or a mixture thereof is dispersed in an aqueous solution or an alcohol solution in which boric acid and urea are dissolved, and then the solvent is evaporated and dried to form a precursor. The boron nitride according to any one of claims 1 to 5 by heating in a non-oxidizing atmosphere.
A method for producing boron nitride / oxide composite particles, characterized by obtaining oxide composite particles. 7. An ultraviolet ray blocking agent characterized by containing boron nitride / oxide composite particles in which amorphous and / or crystalline boron nitride is composited into an oxide, a composite oxide or a mixture thereof.