JPH09132409A - Production of dispersion of ultrafine particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a dispersion of ultrafine particles having high visible ray transparency and UV ray shielding ability and excellent in dispersibility and dispersion stability of the ultrafine particles by dispersing a raw material of ultrafine particles in a medium with an agitating mill and/or ball mill in the presence of SiO2 sol, Al2 O3 sol and TiO2 sol. SOLUTION: The raw material of ultrafine particles is dispersed in the medium by interposing a media with an agitating mill and/or ball mill in the presence of more than one kind among sols of SiO2 , Al2 O3 and TiO2 . In this way, the dispersion of the ultramicro particles good in dispersibility and dispersion stability is produced efficiently. This dispersion of the ultramicro particles exhibits a high light transmissivity at a visible ray region and manifests a high shielding property at an UV ray region and also this dispersion is excellent in dispersion stability with time.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an ultrafine particle dispersion having excellent dispersibility and dispersion stability. More specifically, it relates to a method for producing an ultrafine particle dispersion having excellent dispersibility and dispersion stability, high transparency in the visible light region, and high ultraviolet ray shielding property.

[0002]

2. Description of the Related Art Sunlight reaching the earth (infrared rays, visible rays,
Of the (UV), 5-6% is UV. It is known that ultraviolet rays are electromagnetic waves having a short wavelength and hence high energy, have a decomposability for many substances, and widely damage living organisms.

In recent years, TiO ₂ and ZnO having characteristics such as visible light transparency, ultraviolet shielding ability, chemical stability and nontoxicity.
The fine particles are applied to the fields of food / pharmaceutical packaging and cosmetics. A dispersion containing fine particles having such properties can also prevent the loss of color due to the packaging material in the case of the packaging field by increasing the transparency in the visible light region, and can prevent the whitening in the case of cosmetics. It is desirable to block ultraviolet rays while maintaining transparency in the visible light range.

In order to effectively exhibit the shielding ability in the ultraviolet region while maintaining the high transparency in the visible light region, it is necessary to miniaturize the fine particles into ultrafine particles and bring them into a highly dispersed state. However, when ultrafine particles of TiO ₂ and ZnO are used, dispersibility and dispersion stability due to their strong cohesiveness pose problems. In order to enhance the dispersibility, for example, the pH of the dispersion medium is changed, a dispersant such as sodium hexametaphosphate or sodium pyrophosphate or a surfactant is added, and the surface of TiO ₂ ultrafine particles is SiO ₂ or Al ₂ O ₃ etc. A known method is a method of coating and modifying with.

Further, a method for producing a titanium oxide dispersion liquid (Japanese Patent Laid-Open No. 6-279725) discloses a method of dispersing TiO ₂ in a binder and using TiO ₂ or ZrO ₂ as the material of the dispersion medium. There is. Furthermore, in pigment dispersion stabilization by adsorption of ultrafine particles (Fujitani, Kato; Journal of Coloring Materials, Vol. 68, No. 8, pp. 463-472 (1995)), BaSO ₄ ultrafine particle powder was added to disperse TiO _2, etc. The result of doing is reported.

However, even when these methods are used,
It is difficult to completely disperse the aggregated ultrafine particles, and the dispersibility and dispersion stability of the manufactured dispersion liquid are not always sufficient. Therefore, the visible light transparency of the dispersions obtained by these methods was not satisfactory.

On the other hand, in the ultraviolet-shielding composite fine particles, the method for producing the same, and the cosmetic (WO95 / 09895),
An example in which MgF ₂ sol is added to disperse TiO ₂ by a stirring mill and an example in which SiO ₂ sol is added to disperse ZnO by a high pressure disperser (nanomizer) are disclosed. However, at present, MgF ₂ sol is not industrially produced and is expensive, and in addition, SiO ₂ sol and Al
Compared with ₂ O ₃ sol and TiO ₂ sol, there is a problem that the effect of improving dispersibility and dispersion stability is low, and the high-pressure disperser has a lower dispersion capacity than a stirring mill or a ball mill and completely disperses aggregated ultrafine particles. It was difficult to do.

[0008]

Accordingly, the present invention provides
An object of the present invention is to provide a method for producing an ultrafine particle dispersion, which is excellent in dispersibility and dispersion stability of ultrafine particles having high visible light transparency and ultraviolet ray shielding ability.

[0009]

Means for Solving the Problems As a result of studying dispersion conditions of ultrafine particles, the present inventors have found that SiO ₂ sol,
In the presence of Al ₂ O ₃ sol and TiO ₂ sol, the ultrafine particle raw material was dispersed in the medium through a medium by a stirring mill or a ball mill. As a result, an ultrafine particle dispersion liquid having good dispersibility and dispersion stability was obtained. They have found that they can be manufactured and have completed the present invention.

That is, the gist of the present invention is (1) SiO
Characterized in that the ultrafine particle raw material is dispersed in the medium through a medium by a stirring mill and / or a ball mill in the presence of one or more sol selected from the group consisting of ₂ sol, Al ₂ O ₃ sol and TiO ₂ sol. A method for producing an ultrafine particle dispersion, (2) the ultrafine particle raw material is TiO ₂ , ZnO,
CeO ₂ , BaTiO ₃ , CaTiO ₃ , SrTiO ₃
And the production method according to (1) above, which is one or more substances selected from the group consisting of SiC, and (3) above, wherein the average particle size of the primary particles of the ultrafine particle raw material is 0.001 to 0.5 μm. ) Or (2) the production method, (4) the concentration of ultrafine particles in the resulting dispersion is 0.1 to 20% by weight.
The production method according to any one of (1) to (3) above,
(5) The production method according to any one of (1) to (4) above, wherein the amount of solid content in the sol of the sol used is 10 to 10,000 parts by weight relative to 100 parts by weight of ultrafine particles.
(7) The production method according to any one of (1) to (5) above, wherein the average particle size of the medium is 0.001 to 1.0 mm.
The production method according to any one of the above (1) to (6), wherein the filling amount of the medium is 50 to 95% by volume of the apparatus volume, and (8) the obtained ultrafine particle dispersion liquid has a particle concentration of 0.
When the light transmittance was measured by UV-visible spectroscopic analysis using an optical cell with an optical path length of 1 mm adjusted to 5% by weight, a wavelength of 3
The manufacturing method according to any one of (1) to (7) above, wherein the minimum transmittance at 20 to 400 nm is 5% or less, and the average transmittance at wavelengths of 410 nm and 800 nm is 10% or more. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an ultrafine particle dispersion of the present invention comprises a stirring mill and a stirring mill in the presence of at least one sol selected from the group consisting of SiO ₂ sol, Al ₂ O ₃ sol and TiO ₂ sol. It is characterized in that the ultrafine particle raw material is dispersed in the medium through a medium by a ball mill.

1) Ultrafine particle raw material The ultrafine particle raw material used in the present invention is not particularly limited, but a substance that does not absorb in the visible light region and at the same time has an absorptivity for ultraviolet rays is preferable. That is, a substance having an exciton absorption edge based on the bandgap energy in the wavelength region of ultraviolet rays, that is, a semiconductor compound having a bandgap energy of 3.0 to 4.0 eV is preferable.
For example, TiO ₂ , ZnO, CeO ₂ , BaTiO ₃ , C
Since aTiO ₃ , SrTiO ₃ and SiC strongly exhibit their properties, one or more substances selected from the group consisting of these substances are preferably used. Among these, Ti
Generally, O ₂ , ZnO and CeO ₂ are often used as an ultraviolet shielding agent, one or more selected from the group consisting of these is more preferable, and TiO ₂ or ZnO is particularly preferable.

The ultrafine particle raw material can be added to a stirring mill and / or a ball mill in a state where the primary particles are agglomerated, that is, in the form of lumps, particles, powder, mud and suspension. The ultrafine particles may be surface-modified by coating, topochemical reaction, mechanochemical reaction, encapsulation, precipitation reaction, or the like.

The particle size of the ultrafine particles used in the present invention is not particularly limited as long as the ultrafine particles are dispersed in the medium, but the average particle size of the primary particles of the ultrafine particle raw material is 0.001 to 0. It is preferably 5 μm. The average particle size is preferably 0.001 μm or more from the viewpoint that the degree of improvement in the visible light transparency and the ultraviolet shielding property is smaller than the increase in the energy required for dispersion, and from the viewpoint of forming a stable dispersion liquid, It is preferably 5 μm or less. Further, from the viewpoint of more satisfying the transparency in the visible light region and the shielding property in the ultraviolet region, 0.003 to 0.1 μm
Is more preferable, and 0.005-0.05 μm is particularly preferable.

In the present specification, the average particle size of the primary particles of ultrafine particles is the arithmetic average of the major axis diameter and the minor axis diameter in plane projection, and is a value measured by an electron microscope. The ultrafine particles are ultrafine particles contained in the raw material for the ultrafine particles. The shape of the ultrafine particles is not particularly limited and may be spherical, plate-shaped or needle-shaped.

The concentration of ultrafine particles in the resulting dispersion is not particularly limited, but is preferably 0.1 to 20% by weight,
5 to 10% by weight is more preferable, and 1 to 8% by weight is particularly preferable. 20% by weight from the viewpoint of suppressing re-aggregation of ultrafine particles
The following is preferable, and 0.1% by weight or more is preferable from the viewpoint of productivity. When the re-aggregation of ultrafine particles occurs, the dispersibility and dispersion stability are significantly reduced, and it tends to be difficult to obtain the target dispersion liquid having high visible light transparency. In the present specification, the term “dispersion liquid” refers to a mixture of ultrafine particles and a medium in the presence of a sol according to the method of the present invention, unless otherwise specified.
Dispersed.

2) Sols Sols used in the present invention include SiO ₂ sol and Al.
1 selected from the group consisting of ₂ O ₃ sol and TiO ₂ sol
It is a sol of more than one species. Fine particles having a relatively small particle size, such as the ultrafine particles used in the present invention, tend to agglomerate, and thus it is difficult to disperse them in a medium to exhibit their function well. Also in the present invention, when the ultrafine particles to be used are aggregated, the transparency in the visible light region is impaired, so it is important to sufficiently disperse the ultrafine particles in the medium. Therefore, SiO which is a sol having good dispersibility
By dispersing the ultrafine particle raw material in the medium in the presence of one or more sol selected from the group consisting of ₂ sol, Al ₂ O ₃ sol and TiO ₂ sol, the dispersibility and dispersion stability of the ultrafine particles in the medium It is possible to improve the sex. This is S
When an iO ₂ sol, Al ₂ O ₃ sol or TiO ₂ sol is added to the ultrafine particle suspension, (1) it serves as a medium, and (2) it is adsorbed on the surface of the ultrafine particles and electrostatic repulsion force is exerted. It is considered that it has a role like a dispersant to be imparted.

The quantitative relationship between the sol and the ultrafine particles in the present invention is not particularly limited, but the more the sol is, the more preferable from the viewpoint of dispersibility of the ultrafine particles. Specifically, the amount of solid content in the sol of the sol used, that is, SiO ₂ sol, Al
1 selected from the group consisting of ₂ O ₃ sol and TiO ₂ sol
The amount of the solid content in the sol of one kind or more is preferably 10 to 10,000 parts by weight with respect to 100 parts by weight of the ultrafine particles, and 50
˜5000 parts by weight is more preferred, and 100 to 1000 parts by weight is even more preferred. The amount is preferably 10 parts by weight or more from the viewpoint of exerting the effect of dispersing the ultrafine particles, and is preferably 10,000 parts by weight or less from the viewpoint of maintaining the visible light transparency and the ultraviolet shielding property.

The particle size of the particles constituting the sol is not particularly limited as long as the dispersibility and dispersion stability of the ultrafine particles are good, but the average particle size of the primary particles of the particles is 0.0
01 to 0.5 μm is preferable. From the viewpoint of forming a stable dispersion, it is preferably 0.5 μm or less, and more preferably 0.001 μm or more from the viewpoint of easy preparation. Further, from the viewpoint of further satisfying the transparency in the visible light region and the shielding property in the ultraviolet region, 0.002 to 0.1 μm is more preferable,
0.003 to 0.05 μm is particularly preferable.

In the present specification, the average particle diameter of the primary particles of the particles constituting the sol is the arithmetic average of the major axis diameter and the minor axis diameter in plane projection, and is a value measured by an electron microscope. The shape of the particles forming the sol is not particularly limited, and may be spherical, plate-like, needle-like, or the like. Further, the concentration of particles constituting the sol is not particularly limited, and it is preferable that the concentration of the sol and the ultrafine particles is satisfied. The medium constituting the sol may be water or an organic solvent, and may be the same as or different from the medium in the dispersion liquid.

3) Medium As the medium for preparing the dispersion liquid used in the present invention, either water or an organic solvent can be used. Further, in order to improve dispersibility and dispersion stability of the ultrafine particles, a dispersant or a thickener may be added. Examples of organic solvents include methanol,
Alcohols such as ethanol, chloroform, 1, 2
Examples include halogen-based hydrocarbons such as dichloroethane and trichloroethylene, aromatics such as toluene and xylene, amides such as N, N-dimethylformamide, dimethylsulfoxide, and hexamethylphosphoramide, and mixed solvents thereof. Of these, water, alcohols and mixed solvents thereof are preferable, and water, ethanol and mixed solvents thereof are more preferable.

4) Stirring mill and ball mill In dispersing the ultrafine particles, the dispersing machine is a stirring mill and / or
Alternatively, a ball mill can be used to produce the dispersion liquid most efficiently, and it is preferable to use a stirring mill. At that time, it is also possible to combine the preliminary dispersion with another disperser such as a homomixer or a homogenizer. The reason is that by preliminarily dispersing, the agglomerated ultrafine particles are crushed and crushed, whereby the load required for the subsequent dispersion can be reduced and the ultrafine particles can be efficiently dispersed.

The stirring mill is a crushing machine in which a medium is put in a container and a force is transmitted by a stirring mechanism inserted in the medium to perform crushing, and a tower type mill, a stirring tank type mill, a flow tube type mill, It is classified as a circular mill. Among the stirring mills, examples of stirring tank type mills are Attritor (manufactured by Mitsui Mining Co., Ltd.) and Sand Grinder (IMEX Co., Ltd.).
There are Dino Mill (made by Willy A. Bakofen AG), Super Apex Mill (made by Kotobuki Giken Kogyo Co., Ltd.), and Ultra Visco Mill (made by AIMEX Co., Ltd.). , An example of a circular mill is a pearl mill (made by Dreiswerke GmbH),
There is a diamond fine mill (manufactured by Mitsubishi Heavy Industries, Ltd.). The ball mill is a crusher that normally puts a medium in a mill of a cylindrical container and crushes by moving the mill, and is classified as a rolling mill, a vibrating ball mill, a planetary mill and the like. Examples of such ball mills include AQUAMIZER (manufactured by Hosokawa Micron Co., Ltd.) and HEIGY (manufactured by Kurimoto Iron Works Co., Ltd.).

When the ultrafine particles are dispersed using a stirring mill and / or a ball mill, the disperser may be either an open type or a closed type. The medium used is not particularly limited, but its average particle size is preferably 0.001 to 1.0 mm, more preferably 0.01 to 0.5 mm. Since the smaller the particle size, the higher the dispersion efficiency, 1.0 mm or less is preferable, and 0.001 from the viewpoint of the separability of the dispersion liquid and the medium.
mm or more is preferable. The average particle size of the medium is the arithmetic average of the major axis diameter and the minor axis diameter at the time of plane projection, and is a value measured by a microscope.

The medium filling amount (bulk volume basis) is not particularly limited, but the filling amount is preferably 50 to 95% by volume of the apparatus volume (total volume in the case of the open type), and 60 to 92.
Volume% is more preferable, and 70 to 90 volume% is further preferable. As the amount of media increases, the distribution efficiency increases, so
50% by volume or more is preferable, and 95% by volume or less is preferable from the viewpoint of reduction in volumetric efficiency and increase in power. As the material of the medium, glass, ceramics such as zirconia, metal such as stainless steel, and the like can be used, but it is preferable to use glass because it is inexpensive and chemically stable.

5) Manufacturing process As a first step, the sol, the ultrafine particle raw material and the medium are mixed to obtain a raw material liquid. The mixer used for mixing is not particularly limited, and a stirring mill and / or a ball mill used for dispersion may be used.

In the next step, the obtained raw material liquid is treated with a stirring mill and / or a ball mill through the medium to disperse the ultrafine particles in the medium. When using a stirring mill, the number of revolutions of the stirrer is not particularly limited,
The higher the peripheral speed of the tip of the stirring blade, the better, 7-10
It is preferably 0 m / s, more preferably 10 to 60 m / s, and further preferably 13 to 30 m / s. When a ball mill is used, for example, when a planetary mill is used, the centrifugal acceleration is not particularly limited, but the higher the centrifugal acceleration, the better.
It is preferably 50G. The processing time by the mill is not particularly limited and may be 1 minute to 10 hours. When both the stirring mill and the ball mill are used, either one may be used first.

The ultrafine particle dispersion obtained by the above method has a high transparency in the visible light region and a high ultraviolet ray shielding property. Such optical characteristics can be quantified by, for example, measuring the light transmittance by ultraviolet / visible light spectroscopic analysis. As preferable optical characteristics of the ultrafine particle dispersion liquid, the obtained ultrafine particle dispersion liquid is diluted with water to a particle concentration of 0.
When the light transmittance was measured by UV-visible spectroscopic analysis using an optical cell with an optical path length of 1 mm adjusted to 5% by weight, a wavelength of 3
The minimum transmittance at 20 to 400 nm is 5% or less, and the average transmittance at wavelengths of 410 nm and 800 nm is 10% or more. The average value of the transmittances at 410 nm and 800 nm is more preferably 30% or more, and particularly preferably 50% or more. With this performance, it is possible to satisfy the transparency in the visible light region and the shielding property in the ultraviolet region.

The ultrafine particle dispersion obtained by the method of the present invention is also excellent in dispersion stability and can retain desired properties for a long period of time. Therefore, it can be suitably used in the fields of packaging materials and cosmetics.

[0030]

The present invention will be described in more detail with reference to examples and comparative examples of the present invention, but the present invention is not limited to these examples.

Example 1 43.75 g of TiO ₂ sol (manufactured by Taki Chemical Co., Ltd., TiO ₂ concentration 4% by weight, average particle size 0.01 μm), ZnO ultrafine particles (FINEX75, manufactured by Sakai Chemical Industry, average particle size 0) .01μ
m) 1.75 g and water were mixed to obtain 175 g, which was used as a raw material liquid (that is, the concentration of TiO ₂ and ZnO in the raw material liquid was 1.0% by weight, respectively, and the TiO ₂ sol had a solid content of ZnO). It contains the same amount).

To this raw material solution, 325 g of glass beads (BZ-1, manufactured by Iuchi Seieidou Co., Ltd.) having an average particle diameter of 0.1 mm was added, and an open type sand grinder (TS
G-6H, manufactured by IMEX Co., Ltd., was used to measure the peripheral speed of 7
The dispersion treatment was performed for 2 hours under the condition of m / s. The filling amount of glass beads was 55% by volume of the volume of the sand grinder. The concentration of ZnO ultrafine particles in the obtained dispersion was 1.0% by weight.

The dispersion thus obtained was diluted with water to prepare 10 g of a suspension in which 0.5% by weight of ZnO was suspended. About this UV-visible spectrophotometer (UV-160 manufactured by Shimadzu Corporation)
The light transmittance was measured according to A). The result of measuring the light transmittance in the wavelength range of 200 to 800 nm using a quartz cell having an optical path length of 1 mm is as shown in FIG.

In this figure, the minimum transmittance (value at 320 nm) in the wavelength range of 320 to 400 nm is 0%, and at the same time, the average value of the transmittances at 410 nm and 800 nm is 71%, which means that light is transmitted in the entire visible light range. The rate was extremely high, and it was found that the ultrafine particle dispersion had high transparency in the visible light region and high shielding property in the ultraviolet light region. Further, the obtained dispersion was allowed to stand at room temperature for 3 months, and then the transmittance was measured by the same method. However, there was no change in the transmittance, and no remarkable precipitation of ultrafine particles was observed. The stability was confirmed.

Example 2 64 g of Al ₂ O ₃ sol (alumina sol-520, manufactured by Nissan Chemical Industries, Ltd., Al ₂ O ₃ concentration 20.5% by weight, average particle size 0.04 μm), TiO ₂ ultrafine particles (Ishihara) Sangyo Co., Ltd. TTO-51 (A), rutile type, average particle size 0.
02 μm) 4.375 g of water and 175 g of water were mixed to obtain a raw material liquid (that is, the concentrations of Al ₂ O ₃ and TiO _{2 in} the raw material liquid were 7.5% by weight and 2.5% by weight, respectively, Al ₂ O ₃ sol has ₃ % of TiO ₂ as solid content.
It contains double the amount).

This raw material liquid was subjected to a dispersion treatment for 4 hours under the same conditions as in Example 1. The concentration of TiO ₂ ultrafine particles in the obtained dispersion was 7.5% by weight. The obtained dispersion liquid was diluted with water, and the wavelength range 2 was obtained by the same method as in Example 1.
When the light transmittance at 00 to 800 nm was measured, the minimum transmittance at a wavelength of 320 to 400 nm (320 nm
Value) is 2.3% and at the same time 410
The average value of the transmittance at 31 nm and 800 nm is 31% and the light transmittance is high in the entire visible light range, and the ultrafine particle dispersion liquid has high transparency in the visible light region and high shielding property in the ultraviolet light region. I found out. The transmittance of the obtained dispersion was allowed to stand for 3 months at room temperature, and then the transmittance was measured by the same method. However, there was no change in the transmittance and no remarkable precipitation of ultrafine particles was observed, and the dispersion was stable. The sex was confirmed.

Example 3 SiO ₂ sol (ST-C, SiO manufactured by Nissan Chemical Industries, Ltd.)
₂ Concentration 20.5% by weight, average particle diameter 0.01 μm) 128
g, ZnO ultrafine particles (FINEX75, manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.01 μm) 8.75 g and water were mixed to obtain 175
g as a raw material liquid (that is, the concentrations of SiO ₂ and ZnO in the raw material liquid are 15% by weight and 5% by weight, respectively, and the SiO ₂ sol contains 3 times the solid content of ZnO). .

This raw material liquid was subjected to a dispersion treatment for 2 hours under the same conditions as in Example 1. The concentration of the ZnO ultrafine particles in the obtained dispersion was 5% by weight. The obtained dispersion liquid was diluted with water and treated in the same manner as in Example 1 in the wavelength range of 200 to 8
When the light transmittance at 00 nm was measured, a wavelength of 320 to
The minimum transmittance at 400 nm (value at 320 nm) is 0%, while at the same time 410 nm and 80 nm.
The average value of the transmittance at 0 nm is 90% and the light transmittance is extremely high in the entire visible light range, and the ultrafine particle dispersion liquid has high transparency in the visible light region and high shielding property in the ultraviolet light region. I found out. The transmittance of the obtained dispersion was allowed to stand for 3 months at room temperature, and then the transmittance was measured by the same method. However, there was no change in the transmittance and no remarkable precipitation of ultrafine particles was observed, and the dispersion was stable. The sex was confirmed.

Example 4 SiO ₂ sol (ST-C, SiO manufactured by Nissan Chemical Industries, Ltd.)
₂ concentration 20.5% by weight, average particle diameter 0.01 μm) 4.8
8 kg of TiO ₂ ultrafine particles (TTO- manufactured by Ishihara Sangyo Co., Ltd.)
51 (A), rutile type, average particle size 0.02 μm) 1 kg
And water were mixed to obtain 10 kg, which was used as a raw material liquid (that is,
The concentration of SiO ₂ and TiO _{2 in} the raw material liquid is 1 each.
0% by weight, and the silica sol contains an equal amount of TiO ₂ as a solid content).

KDL-PILO, which is a stirring mill, is prepared by filling the raw material liquid with glass beads having an average particle size of 0.25 mm (UB1113L, manufactured by Union Co., Ltd.) to a volume of 80%.
Using a T-type Dyno mill (manufactured by Willie A. Bakofen), 8-pass operation was carried out under the conditions of a peripheral speed of 14 m / s and a residence time of 8 minutes to carry out a dispersion treatment. The concentration of TiO ₂ ultrafine particles in the obtained dispersion was 10% by weight.

The obtained dispersion was diluted with water and the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as in Example 1. The minimum transmittance in the wavelength of 320 to 400 nm (value at 320 nm) ) Is 0%, and the average value of the transmittances at 410 nm and 800 nm is 59%, which means that the light transmittance is high in the entire visible light range, and the ultrafine particle dispersion has a high transparency in the visible light range. It has been found that it has a high light blocking effect and a high shielding property in the ultraviolet region. The transmittance of the obtained dispersion was allowed to stand for 3 months at room temperature, and then the transmittance was measured by the same method. However, there was no change in the transmittance and no remarkable precipitation of ultrafine particles was observed, and the dispersion was stable. The sex was confirmed.

Example 5 SiO_TwoSol (ST-C, manufactured by Nissan Chemical Industries, Ltd., Si
O_Two(Concentration 20.5% by weight, average particle diameter 0.01 μm) 61
g, TiO_TwoUltrafine particles (MT-600B, Teika Co., Ltd.)
Made, MT-600B, rutile type, average particle size 0.05μ
m) 87.5g and water are mixed to make 1000g,
Liquid (that is, SiO of the raw material liquid)_TwoAnd TiO_Twoof
The concentrations were 1.25 wt% and 8.75 wt% respectively.
, SiO _TwoSol is TiO as solid content_Two0.14 times
The amount is contained).

A homogenizer (TK-RO) was added to this raw material liquid.
1200 using BOMICS, Tokushu Kika Kogyo (manufactured)
After preliminary dispersion at 90 rpm for 90 minutes, the dispersion treatment was performed under the same conditions as in Example 4 while stirring at 7,000 rpm.

The resulting dispersion (the concentration of TiO ₂ was 8.7
5% by weight) was diluted with water, and the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as in Example 1. The minimum transmittance in the wavelength of 320 to 400 nm was 0.
At the same time, the average value of the transmittances at 410 nm and 800 nm is 16% and the light transmittance is high in the entire visible light range, and the ultrafine particle dispersion liquid has high transparency in the visible light range and ultraviolet rays. It was found to have a high shielding property in the area.

Further, the dispersion thus obtained was allowed to stand at room temperature for 3 months, and then the transmittance was measured by the same method. However, there was no change in the transmittance and no remarkable precipitation of ultrafine particles was observed. ,
The stability of dispersion was confirmed.

Example 6 SiO ₂ sol (ST-C, manufactured by Nissan Chemical Industries, Ltd., Si
O ₂ concentration 20.5% by weight, average particle diameter 0.01 μm) 2
1.3 g, CeO ₂ ultrafine particles (Seriguard S-3018
-02, manufactured by Japan Inorganic Chemical Industry Co., Ltd., CeO ₂ concentration 2
4.6% by weight, 3.56 g of CeO ₂ average particle size 0.04 μm (Seriguard average particle size 2 μm) and water were mixed to obtain 1
The raw material liquid was set to 75 g (that is, SiO 2 of the raw material liquid).
The concentrations of ₂ and CeO ₂ are 2.5% by weight and 0.
5% by weight, and the SiO ₂ sol has a solid content of TiO ₂
5 times the amount of).

A planetary ball mill (Heidi B
X254, manufactured by Kurimoto Iron Works Co., Ltd., was used for dispersion treatment for 4 hours under the conditions of a filling amount of 50% by volume and 100 G. The obtained dispersion liquid (concentration of CeO ₂ is 0.5% by weight) is diluted with water, and the same procedure as in Example 1 is carried out to obtain a wavelength range of 200-80.
When the light transmittance at 0 nm was measured, the wavelength was 320-4.
The minimum transmittance at 00 nm is 0%, and at the same time, the average transmittance at 410 nm and 800 nm is 12%, which is a high light transmittance over the entire visible light range. It was found that it has high transparency in the light region and high shielding property in the ultraviolet region.

Further, the resulting dispersion was allowed to stand at room temperature for 3 months, and then the transmittance was measured by the same method. However, there was no change in the transmittance and remarkable precipitation of ultrafine particles was observed. The stability of dispersion was confirmed.

Comparative Example 1 SiO ₂ sol (ST-C, SiO manufactured by Nissan Chemical Industries, Ltd.)
₂ Concentration 20.5% by weight, average particle diameter 0.01 μm) 122
g, TiO ₂ ultrafine particles (TTO-51 manufactured by Ishihara Sangyo Co., Ltd.)
(A), rutile type, 5 g of average particle size 0.02 μm) and water were mixed to make 1000 g to make a raw material liquid (that is, the concentration of SiO ₂ and TiO _{2 in} the raw material liquid was 2.5, respectively).
Wt% and 0.5 wt%, and the SiO ₂ sol contains 5 times the amount of TiO ₂ as a solid content).

This raw material liquid was subjected to a pressure of 1 using a high pressure disperser (Nanomizer LA31, Nanomizer (manufactured by Co.)).
The dispersion treatment was performed under the conditions of 300 kgf / cm ² and 20 passes. The resulting dispersion was diluted with water and used in Example 1.
When the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as described above, the minimum transmittance (value at 320 nm) in the wavelength of 320 to 400 nm was 0%, but the TiO ₂ ultrafine particles were completely removed. Since it was not dispersed, the average value of the transmittances at 410 nm and 800 nm was 4%, which was a low value in the entire visible light range, and did not show high transparency in the visible light range.

Comparative Example 2 TiO ₂ ultrafine particles (TTO-51 manufactured by Ishihara Sangyo Co., Ltd.)
(A), rutile type, average particle size 0.02 μm) 4.375
g and water were mixed to make 175 g, which was used as a raw material liquid (that is, the raw material liquid had a TiO ₂ concentration of 2.5 wt%, and did not contain SiO ₂ sol and Al ₂ O ₃ sol. is there).

This raw material liquid was dispersed for 4 hours under the same conditions as in Example 1. The obtained dispersion was diluted with water, and the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as in Example 1. As a result, TiO ₂ ultrafine particles were aggregated and immediately precipitated, Wavelength 320-40
The minimum transmittance at 0 nm was 96% in the ultraviolet region with a wavelength of 320 nm, and the high transmittance was not shown in the ultraviolet region.

Comparative Example 3 ZnO ultrafine particles (FINEX75, manufactured by Sakai Chemical Co., Ltd., average particle diameter 0.01 μm) 4.375 g and water were mixed to obtain 175 g.
To obtain a raw material liquid (that is, the concentration of TiO _{2 in} the raw material liquid is 2.5% by weight, and SiO ₂ sol and Al ₂ O ₃
It does not contain a sol).

This raw material liquid was subjected to a dispersion treatment for 2 hours under the same conditions as in Example 1. The obtained dispersion was diluted with water, and the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as in Example 1. The ZnO ultrafine particles were immediately aggregated because they were aggregated, and the wavelength was measured. 320-400
The minimum transmittance in nm (value at 320 nm) was 99%, which means that the film did not exhibit high shielding properties in the ultraviolet region.

Comparative Example 4 TiO ₂ ultrafine particles (TTO-51 manufactured by Ishihara Sangyo Co., Ltd.)
(A), rutile type, average particle size 0.02 μm) 4.375
g and water were mixed to make 175 g, which was used as a raw material liquid (that is, the raw material liquid had a TiO ₂ concentration of 2.5% by weight and contained neither SiO ₂ sol nor Al ₂ O ₃ sol. is there).

780 g of zirconia beads having an average particle diameter of 0.31 mm (Microhaika Z300, manufactured by Showa Shell Sekiyu KK) was added to this raw material liquid, and the dispersion treatment was carried out for 4 hours under the same conditions as in Example 1 except for the above. The amount of beads filled was 55% by volume of the volume of the sand grinder.

The obtained dispersion was diluted with water, and the light transmittance in the wavelength range of 200 to 800 nm was measured by the same method as in Example 1. As a result, TiO ₂ ultrafine particles were aggregated and immediately precipitated. And the minimum transmittance (value at 320 nm) at wavelengths of 320 to 400 nm is 97%.
And did not show high shielding properties in the ultraviolet range.

From the above results, the ultrafine particle dispersion obtained by the method of the present invention was dispersed without the ultrafine particles settling, and the sedimentation of the ultrafine particles was hardly observed in the dispersion after 3 months. It has been found to exhibit suitable optical characteristics. On the other hand, it was found that the ultrafine particle dispersions in Comparative Examples have poor dispersibility such as precipitation of ultrafine particles and do not exhibit desired optical characteristics.

[0059]

According to the method of the present invention, it is possible to obtain an ultrafine particle dispersion having extremely high dispersibility and dispersion stability. Such an ultrafine particle dispersion has a high light transmittance in the visible light region, exhibits a high shielding property in the ultraviolet region, and is excellent in dispersion stability over time.

[Brief description of the drawings]

FIG. 1 is a diagram showing the measurement results of light transmittance of an ultrafine particle dispersion obtained in Example 1 by an ultraviolet-visible spectrophotometer.

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Claims (8)

[Claims] 1. SiO ₂ sol, Al ₂ O ₃ sol and Ti
A method for producing an ultrafine particle dispersion, which comprises dispersing an ultrafine particle raw material into a medium through a medium with a stirring mill and / or a ball mill in the presence of at least one sol selected from the group consisting of O ₂ sols. . 2. Ultrafine particle raw material is TiO ₂ , ZnO, Ce
The production method according to claim 1, wherein the material is one or more substances selected from the group consisting of O ₂ , BaTiO ₃ , CaTiO ₃ , SrTiO ₃ and SiC. 3. The production method according to claim 1, wherein the primary particles of the ultrafine particle raw material have an average particle size of 0.001 to 0.5 μm. 4. The production method according to claim 1, wherein the concentration of ultrafine particles in the obtained dispersion is 0.1 to 20% by weight. 5. The method according to claim 1, wherein the amount of solid content in the sol of the sol used is 10 to 10,000 parts by weight with respect to 100 parts by weight of the ultrafine particles. 6. The average particle size of the media is 0.001-1.
It is 0 mm, The manufacturing method in any one of Claims 1-5. 7. The filling amount of media is 50 to 9 of the apparatus volume.
It is 5 volume%, The manufacturing method in any one of Claims 1-6. 8. The ultrafine particle dispersion obtained is adjusted to a particle concentration of 0.5% by weight with water, and the light transmittance is measured by ultraviolet-visible spectroscopic analysis using an optical cell having an optical path length of 1 mm. The manufacturing method according to claim 1, wherein the minimum transmittance at 400 nm is 5% or less, and the average value of the transmittances at wavelengths 410 nm and 800 nm is 10% or more.