JP3301690B2 - Method for producing ultrafine particle dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an ultrafine particle dispersion having excellent dispersibility and dispersion stability. More specifically, the present invention 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 shielding properties against ultraviolet rays.

[0002]

2. Description of the Related Art Sunlight (infrared rays, visible rays,
5 to 6% of ultraviolet rays are ultraviolet rays. Ultraviolet rays are short-wavelength, high-energy electromagnetic waves, are decomposable to many substances, and are widely known to damage living organisms.

In recent years, TiO ₂ and ZnO having characteristics such as transparency of visible light, ultraviolet shielding ability, chemical stability and non-toxicity have been developed.
Fine particles have been applied to the fields of food and pharmaceutical packaging, cosmetics, and the like. Dispersions containing fine particles having such properties can also prevent loss of color due to the packaging material in the case of the packaging field and can prevent whitening in the case of cosmetics by increasing the transparency in the visible light region. It is desirable to shield the ultraviolet rays while maintaining the transparency in the visible light region.

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

In a method for producing a titanium oxide dispersion (JP-A-6-279725), a method is disclosed in which TiO ₂ or ZrO ₂ is used as a dispersion medium when TiO ₂ is dispersed in a binder. I have. Further, in the stabilization of pigment dispersion by adsorption of ultrafine particles (Fujitani, Kato; Journal of the Japan Society of Color Materials, Vol. 68, No. 8, pp. 463-472 (1995)), BaSO ₄ ultrafine particle powder is added to disperse TiO _{2 and the} like. Have been 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 produced dispersion 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, a method for producing the same, and a cosmetic (WO95 / 09895),
It discloses an example in which MgF ₂ sol is added and TiO ₂ is dispersed by a stirring mill, and an example in which SiO ₂ sol is added and ZnO is dispersed by a high-pressure disperser (Nanomizer). However, at present, MgF ₂ sol is not industrially produced, is expensive, and has SiO ₂ sol, Al
There is a problem that the effect of improving dispersibility and dispersion stability is lower than ₂ O ₃ sol and TiO ₂ sol, and the high-pressure disperser has a lower dispersing ability 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 liquid, which is excellent in dispersibility and dispersion stability of ultrafine particles having high visible light transparency and ultraviolet shielding ability.

[0009]

Means for Solving the Problems The present inventors have studied the dispersion conditions of ultrafine particles and 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 via a medium by a stirring mill or a ball mill, and an ultrafine particle dispersion having good dispersibility and dispersion stability was efficiently obtained. They found that they could be manufactured and completed the present invention.

That is, the gist of the present invention is that “ SiO ₂ sol,
Al ₂ O ₃ sol and one or more sol selected from the group consisting of TiO ₂ sol, primary particles are aggregated, agglomerated, granular addition
Prepares raw material liquid by mixing powdery ultrafine particle raw material and medium
, And the resultant mixture stirred mills and / or a ball mill by treatment with disperser through the media, the resulting ultrafine <br/> particle child you characterized by dispersing in a medium ultrafine particle dispersion related to the production method "of liquid.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing an ultrafine particle dispersion according to 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. And / or dispersing the ultrafine particle material in a medium by a ball mill through a medium.

1) Raw material of ultrafine particles The raw material of ultrafine particles used in the present invention is not particularly limited, but a substance which does not absorb in the visible light region and has an ultraviolet absorbing property at the same time is preferable. That is, a substance in which the exciton absorption edge based on the band gap energy exists in the ultraviolet wavelength region, that is, a semiconductor compound having a band gap 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 exhibit strong properties, at least one substance selected from the group consisting of these substances is preferably used. Among them, Ti
O ₂ , ZnO and CeO ₂ are commonly used as ultraviolet shielding agents, and one or more selected from the group consisting of these are more preferred, and TiO ₂ or ZnO is particularly preferred.

The raw material for ultrafine particles is in a state in which the primary particles are aggregated, that is, in a lump, granular or powder form, and is stirred by a stirring mill and / or
Or put into a ball mill. The ultrafine particles may be surface-modified by coating, topochemical reaction, mechanochemical reaction, encapsulation, precipitation reaction and 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 a medium. Preferably it is 5 μm. The average particle size is preferably 0.001 μm or more from the viewpoint that the degree of improvement in visible light transparency and ultraviolet shielding properties is smaller than the increase in energy required for dispersion, and from the viewpoint of forming a stable dispersion. 5 μm or less is preferable. Furthermore, 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 to 0.05 μm is particularly preferable.

In the present specification, the average particle diameter of the primary particles of the ultrafine particles is an arithmetic average of the major axis diameter and the minor axis diameter when projected on a plane, and is a value measured by an electron microscope. The ultrafine particles refer to ultrafine particles contained in the ultrafine particle raw material. The shape of the ultrafine particles is not particularly limited, such as a sphere, a plate, or a needle.

The concentration of the ultrafine particles in the obtained 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 wt% or more is preferable from a viewpoint of productivity. When the re-aggregation of the ultrafine particles occurs, the dispersibility and the dispersion stability are remarkably reduced, and it tends to be difficult to obtain the intended 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.
It refers to what is dispersed.

2) Sol The sol used in the present invention is SiO ₂ sol, Al
1 selected from the group consisting of ₂ O ₃ sol and TiO ₂ sol
More than one kind of sol. Fine particles having a relatively small particle diameter, such as ultrafine particles used in the present invention, have a property of easily agglomerating, and it is difficult to disperse them in a medium to express their functions well. Also in the present invention, if the ultrafine particles used are aggregated, the transparency in the visible light region is impaired. Therefore, it is important to sufficiently disperse the ultrafine particles in the medium. Therefore, SiO, which is a sol having good dispersibility, is used.
Dispersion and dispersion stability of the ultrafine particles in the medium by dispersing the ultrafine particle material in the medium in the presence of one or more sols selected from the group consisting of ₂ sol, Al ₂ O ₃ sol and TiO ₂ sol Performance can be improved. This is S
When the TiO ₂ sol, Al ₂ O ₃ sol, or TiO ₂ sol is added to the ultrafine particle suspension, (1) a role as a medium, and (2) an electrostatic repulsion force is adsorbed on the surface of the ultrafine particles. It is considered that it has a role as a dispersant to be applied.

The quantitative relationship between the sol and the ultrafine particles in the present invention is not particularly limited, but the more the sol, the more preferable from the viewpoint of the dispersibility of the ultrafine particles. Specifically, the amount of solids in the sol of the sol to be 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 or more species is preferably 10 to 10000 parts by weight, and
-5000 parts by weight is more preferable, and 100-1000 parts by weight is further preferable. It is preferably at least 10 parts by weight from the viewpoint of exhibiting the effect of dispersing the ultrafine particles, and is preferably at most 10,000 parts by weight from the viewpoint of maintaining the visible light transparency and the ultraviolet shielding property.

The particle diameter of the particles constituting the sol is not particularly limited as long as the dispersibility and dispersion stability of the ultrafine particles are good.
It is preferably from 0.01 to 0.5 μm. The thickness is preferably 0.5 μm or less from the viewpoint of forming a stable dispersion, and is preferably 0.001 μm or more from the viewpoint of ease of preparation. Furthermore, from the viewpoint of more 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 preferred.

In the present specification, the average primary particle diameter of the particles constituting the sol is the arithmetic average of the major axis diameter and the minor axis diameter when projected on a plane, and is a value measured by an electron microscope. The shape of the particles constituting the sol is not particularly limited, such as a sphere, a plate, or a needle. Further, the concentration of the particles constituting the sol is not particularly limited, and is preferably such that the above-mentioned quantitative relationship between the sol and the ultrafine particles is satisfied. The medium constituting the sol may be either water or an organic solvent, and may be the same as or different from the medium in the dispersion.

3) Medium As the medium for preparing the dispersion used in the present invention, either water or an organic solvent can be used. In order to improve the 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
Solvents such as halogenated 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. Among them, water, alcohols or a mixed solvent thereof is preferable, and water, ethanol or a mixed solvent thereof is more preferable.

4) Stirring Mill and Ball Mill In dispersing the ultrafine particles, a dispersing machine uses a stirring mill and / or a ball mill.
Alternatively, the dispersion can be most efficiently produced by using a ball mill, and among them, 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 and a homogenizer. The reason is that, by disintegrating and pulverizing the aggregated ultrafine particles by the preliminary dispersion, the load required for the subsequent dispersion can be reduced, and the ultrafine particles can be efficiently dispersed.

The stirring mill is a crusher in which a medium is placed in a container and crushed by transmitting a force by a stirring mechanism inserted into the medium, and includes a tower mill, a stirring tank mill, a flow tube mill, Classified as annular mills. Among the stirring mills, examples of the stirring tank type mill include an attritor (manufactured by Mitsui Mining Co., Ltd.) and a sand grinder (IMEX Co., Ltd.)
Examples of the flow tube type mill include a Dyno mill (manufactured by Willy A. Bakkofen AG), a super apex mill (manufactured by Kotobuki Giken Kogyo Co., Ltd.), and an ultra biscomil (manufactured by Imex Co., Ltd.) Examples of the annular mill include a pearl mill (manufactured by Dry Swerke GmbH),
There is a diamond fine mill (Mitsubishi Heavy Industries, Ltd.). A ball mill is a pulverizer that usually performs a pulverization by placing a medium in a mill of a cylindrical container and moving the mill to perform pulverization, and is classified into a rolling mill, a vibrating ball mill, a planetary mill, and the like. Examples of such a ball mill include Aquamizer (manufactured by Hosokawa Micron Co., Ltd.) and Heidi (manufactured by Kurimoto Iron Works).

When dispersing the ultrafine particles using a stirring mill and / or a ball mill, the disperser may be either an open type or a closed type. The media used is not particularly limited, but the 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, the diameter is preferably 1.0 mm or less.
mm or more is preferable. The average particle diameter of the medium is an arithmetic average of the major axis diameter and the minor axis diameter when projected on a plane, and is a value measured by a microscope.

The filling amount (based on bulk volume) of the medium 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 an open type), and 60 to 92% by volume.
% Is more preferable, and 70 to 90% by volume is more preferable. As the amount of media increases, the dispersion efficiency increases.
It is preferably at least 50% by volume, and more preferably at most 95% by volume from the viewpoint of lowering volumetric efficiency and increasing power. As the material of the media, glass, ceramics such as zirconia, metals such as stainless steel, and the like can be used. However, glass is preferably used because it is inexpensive and chemically stable.

5) Manufacturing Process As a first step, a sol, a raw material of ultrafine particles and a 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 processed through a medium by a stirring mill and / or a ball mill to disperse ultrafine particles in the medium. When using a stirring mill, the rotation speed of the stirrer is not particularly limited,
The higher the peripheral speed at the tip of the stirring blade, the better, 7-10
It is preferably 0 m / s, more preferably 10 to 60 m / s, even more preferably 13 to 30 m / s. In the case of using a ball mill, for example, when using a planetary mill, the centrifugal acceleration is not particularly limited.
Preferably, it is 50G. The processing time by the mill is not particularly limited, and may be 1 minute to 10 hours. When both a stirring mill and a ball mill are used, either one may be used first.

The ultrafine particle dispersion obtained by the above method has high transparency in the visible light region and high shielding properties against ultraviolet rays. Such optical properties can be quantified, for example, by measuring light transmittance by ultraviolet / visible light spectroscopy. As preferable optical characteristics of the ultrafine particle dispersion, the obtained ultrafine particle dispersion is prepared by adding water to a particle concentration of 0.1%.
When adjusted to 5% by weight and the light transmittance was measured by UV-visible spectroscopy using an optical cell having an optical path length of 1 mm, the wavelength was 3
The minimum transmittance at 20 to 400 nm is 5% or less, and the average value of the transmittance at wavelengths 410 nm and 800 nm is 10% or more. The average value of the transmittance 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.

Further, the ultrafine particle dispersion obtained by the method of the present invention has excellent dispersion stability and can maintain desired properties for a long period of time. Therefore, it can be suitably used in the field 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 Kagaku Co., Ltd., TiO ₂ concentration 4% by weight, average particle size 0.01 μm), ultrafine ZnO particles (FINEX 75, manufactured by Sakai Chemical Co., average particle size 0) .01μ
m) 1.75 g and water were mixed to make 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 was made of ZnO as a solid content. Are contained in equal amounts).

325 g of glass beads having an average particle size of 0.1 mm (BZ-1, manufactured by Iuchi Seieido Co., Ltd.) were added to this raw material liquid, and an open sand grinder (TS) as a stirring mill was added.
G-6H, manufactured by Imex Co., Ltd.)
Dispersion processing was performed for 2 hours under the condition of m / s. The filling amount of the 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 obtained dispersion was diluted with water to prepare 10 g of a 0.5% by weight suspension of ZnO. About this, an ultraviolet-visible spectrophotometer (UV-160 manufactured by Shimadzu Corporation)
The light transmittance was measured according to A). FIG. 1 shows the results of measuring the light transmittance in a wavelength range of 200 to 800 nm using a quartz cell having an optical path length of 1 mm.

In this figure, the minimum transmittance (value at 320 nm) at a wavelength of 320 to 400 nm is 0%, and the average value of the transmittance at 410 nm and 800 nm is 71%. The ratio was a very high value, indicating that the ultrafine particle dispersion had high transparency in the visible light region and high shielding property in the ultraviolet region. After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured by the same method. However, there was no change in the transmittance and no remarkable sedimentation of ultrafine particles was observed. 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 TTO-51 (A) manufactured by Sangyo Co., Ltd., rutile type, average particle size of 0.
(2 μm) 4.375 g and water were mixed to make 175 g, which was used as 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 of TiO ₂ 3 as solids
Twice as much).

This raw material liquid was subjected to a dispersion treatment for 4 hours under the same conditions as in Example 1. The concentration of the TiO ₂ ultrafine particles in the obtained dispersion was 7.5% by weight. The obtained dispersion was diluted with water, and the wavelength region 2 was reduced in the same manner 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) was measured.
At the same time as 2.3%)
The average value of the transmittance at 31 nm and 800 nm is 31%, which is a high value in the entire visible light range, and the ultrafine particle dispersion has high transparency in the visible light range and high shielding property in the ultraviolet range. I understood that. After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured by the same method. The transmittance was unchanged, and no remarkable sedimentation of ultrafine particles was observed. 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 size 0.01 μm) 128
g, 8.75 g of ZnO ultrafine particles (FINEX 75, manufactured by Sakai Chemical Co., average particle size 0.01 μm) and water were mixed together for 175 g.
g, and used as a raw material liquid (that is, the concentrations of SiO ₂ and ZnO in the raw material liquid were 15% by weight and 5% by weight, respectively, and the SiO ₂ sol contained three times the amount of ZnO as a solid). .

This raw material liquid was subjected to a dispersion treatment for 2 hours under the same conditions as in Example 1. The concentration of ZnO ultrafine particles in the obtained dispersion was 5% by weight. The obtained dispersion is diluted with water, and a wavelength range of 200 to 8 is obtained in the same manner as in Example 1.
When the light transmittance at 00 nm was measured,
The minimum transmission at 400 nm (value at 320 nm) is 0%, while at 410 nm and 80 nm.
The average value of the transmittance at 0 nm is 90%, which is a very high value in the entire visible light range, and the ultrafine particle dispersion has high transparency in the visible light range and high shielding property in the ultraviolet range. I understood that. After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured by the same method. The transmittance was unchanged, and no remarkable sedimentation of ultrafine particles was observed. 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 size 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 to make a 10 kg raw material liquid (that is,
The concentration of SiO ₂ and TiO _{2 in} the raw material liquid was 1
0% by weight, and the silica sol contains the same amount of TiO ₂ as solid content).

KDL-PILO, a stirring mill, in which 80% of the volume of this raw material liquid was filled with glass beads (UB1113L, manufactured by Union Co., Ltd.) having an average particle size of 0.25 mm.
Using a T-type dyno mill (manufactured by Willy A. Bakkofen), an 8-pass operation was performed under the conditions of a peripheral speed of 14 m / s and a residence time of 8 minutes to perform dispersion treatment. The concentration of the 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 in the same manner as in Example 1. The minimum transmittance at the wavelength of 320 to 400 nm (the value at 320 nm) was measured. ) Is 0%, and at the same time, the average value of the transmittance at 410 nm and 800 nm is 59%, which is a high value in the entire visible light range, and the ultrafine particle dispersion is highly transparent in the visible light range. It was found that it had high light-shielding properties in the ultraviolet region. After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured by the same method. The transmittance was unchanged, and no remarkable sedimentation of ultrafine particles was observed. Sex was confirmed.

Example 5 SiO_TwoSol (ST-C, manufactured by Nissan Chemical Industries, Ltd., Si
O_TwoConcentration 20.5% by weight, average particle size 0.01 μm) 61
g, TiO_TwoUltra fine particles (MT-600B, Teika Corporation)
, MT-600B, rutile type, average particle size 0.05μ
m) Mix 87.5 g and water to make 1000 g,
Liquid (that is, SiO 2 of the raw material liquid)_TwoAnd TiO_Twoof
The concentrations were 1.25% by weight and 8.75% by weight, respectively.
, SiO _TwoThe sol is TiO_Two0.14 times of
Content).

This raw material solution was homogenized (TK-RO).
BOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.)
After pre-dispersion at 90 rpm for 90 minutes, dispersion treatment was carried out under the same conditions as in Example 4 while stirring at 7000 rpm.

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

After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured in the same manner. The transmittance was unchanged, and no remarkable sedimentation of ultrafine particles was observed. ,
The stability of the 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 size 0.01 μm) 2
1.3 g, CeO ₂ ultrafine particles (Serigard S-3018)
-02, manufactured by Nippon Inorganic Chemical Industry Co., Ltd., CeO ₂ concentration 2
4.65% by weight, 3.56 g of CeO ₂ average particle size 0.04 μm (Serigard average particle size 2 μm)) and water were mixed, and 1
75 g, and used as a raw material liquid (that is, SiO 2 of the raw material liquid)
₂ and CeO ₂ concentrations of 2.5% by weight and 0.
5% by weight, and the SiO ₂ sol is TiO ₂ as a solid content.
5 times the amount of the above).

This raw material liquid was mixed with a planetary ball mill (Higie B
Using X254 (manufactured by Kurimoto Ironworks Co., Ltd.), a dispersion treatment was performed for 4 hours under the conditions of a filling amount of 50% by volume and 100G. The obtained dispersion (the concentration of CeO ₂ is 0.5% by weight) is diluted with water, and the wavelength range of 200 to 80 is obtained in the same manner as in Example 1.
When the light transmittance at 0 nm was measured,
The minimum transmittance at 00 nm is 0%, and at the same time, the average value of the transmittance at 410 nm and 800 nm is 12%, which is a high value over the entire visible light range. It was found to have high transparency in the light ray range and high shielding property in the ultraviolet ray range.

After the resulting dispersion was allowed to stand at room temperature for 3 months, the transmittance was measured in the same manner. The transmittance was unchanged, and remarkable sedimentation of ultrafine particles was observed. And the dispersion stability was confirmed.

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

This raw material liquid was subjected to a pressure of 1 using a high-pressure disperser (Nanomizer LA31, manufactured by Nanomizer Co., Ltd.).
Dispersion treatment was performed under the conditions of 300 kgf / cm ² and 20 passes. The resulting dispersion was diluted with water,
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 (the value at 320 nm) in the wavelength range of 320 to 400 nm was 0%, but the TiO ₂ ultrafine particles were completely removed. Since the particles were not dispersed, the average value of the transmittance 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 Ultrafine TiO ₂ particles (TTO-51 manufactured by Ishihara Sangyo Co., Ltd.)
(A), rutile type, average particle size 0.02 μm) 4.375
g and water to obtain 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 did not contain SiO ₂ sol and Al ₂ O ₃ sol). is there).

This raw material liquid was subjected to a dispersion treatment for 4 hours under the same conditions as in Example 1. The obtained dispersion was diluted with water, and the light transmittance in a wavelength range of 200 to 800 nm was measured by the same method as in Example 1. As a result, TiO ₂ ultrafine particles settled out immediately because they were aggregated, Wavelength 320-40
The minimum transmittance at 0 nm was 96% in the ultraviolet region with a wavelength of 320 nm, indicating no high shielding property in the ultraviolet region.

COMPARATIVE EXAMPLE 3 4.375 g of ultrafine ZnO particles (FINEX 75, manufactured by Sakai Chemical Co., average particle size 0.01 μm) and 175 g of water were mixed.
(That is, the TiO ₂ concentration of the raw material liquid was 2.5% by weight, and the SiO ₂ sol and Al ₂ O ₃
It does not contain 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 a wavelength range of 200 to 800 nm was measured in the same manner as in Example 1. As a result, the ZnO ultrafine particles precipitated immediately because they were aggregated. 320-400
The minimum transmittance in nm (value at 320 nm) was 99%, indicating no high shielding property in the ultraviolet region.

Comparative Example 4 Ultrafine TiO ₂ particles (TTO-51 manufactured by Ishihara Sangyo Co., Ltd.)
(A), rutile type, average particle size 0.02 μm) 4.375
g and water to obtain 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 did not contain SiO ₂ sol and Al ₂ O ₃ sol). is there).

To this raw material liquid, 780 g of zirconia beads having an average particle diameter of 0.31 mm (Micro Haica Z300, manufactured by Showa Shell Sekiyu KK) were added, and dispersion treatment was carried out for 4 hours under the same conditions as in Example 1 except for the above. The filling amount of the beads 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 in the same manner as in Example 1. As a result, the TiO ₂ ultrafine particles immediately settled out due to aggregation. The minimum transmittance (value at 320 nm) at a wavelength of 320 to 400 nm is 97%.
And did not show high shielding properties in the ultraviolet region.

From the above results, the ultrafine particle dispersion obtained by the method of the present invention was dispersed without sedimentation of the ultrafine particles, and the dispersion after three months showed almost no sedimentation of the ultrafine particles. It turned out that it shows suitable optical characteristics. On the other hand, it was found that the ultrafine particle dispersion in the comparative example had poor dispersibility, such as precipitation of ultrafine particles, and did 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 liquid has a high light transmittance in the visible light region, exhibits high shielding properties in the ultraviolet light region, and has excellent dispersion stability over time.

[Brief description of the drawings]

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

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-298520 (JP, A) JP-A-3-215312 (JP, A) JP-A-5-178606 (JP, A) JP-A-5-178606 170424 (JP, A) JP-A-6-127932 (JP, A) JP-A-7-89710 (JP, A) JP-A 5-132309 (JP, A) JP-A 8-268707 (JP, A) JP-A-6-100358 (JP, A) JP-A-6-279725 (JP, A) JP-A-8-12961 (JP, A) JP-A-6-115924 (JP, A) International publication 95/9895 ( WO, A1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C01B 33/00-33/193

Claims (8)

(57) [Claims] 1. An SiO ₂ sol, an Al ₂ O ₃ sol and Ti
One or more sols selected from the group consisting of O ₂ sols , primary
Agglomerated, aggregated, granular or powdered ultrafine particles
And a medium are mixed to prepare a raw material liquid, and the obtained mixed liquid is
Stir mill and / or ball mill via media
Method for producing ultrafine particle dispersion liquid characterized in that treated with disperser, to disperse the generated ultra fine particles in the medium. 2. The raw material for ultrafine particles is TiO ₂ , ZnO, Ce.
_{O 2, BaTiO 3, CaTiO 3} , SrTiO 3 and the manufacturing method of one or more Tona Ru claim 1 selected from the group consisting of SiC. 3. The method according to claim 1, wherein the average particle diameter of the primary particles of the ultrafine particle raw material is 0.001 to 0.5 μm. 4. A method according claim 1 or you adjust the concentration of ultrafine particles 0.1 to 20 wt% in dispersion obtained. (5) The amount of solids in the sol is 10 to 10000 parts by weight based on 100 parts by weight of ultrafine particles.
4. The manufacturing method according to any one of the above items. 6. The media having an average particle size of 0.001 to 1.
The method according to claim 1, wherein the thickness is 0 mm. 7. The production method according to claim 1, wherein the filling amount of the medium is 50 to 95% by volume of the apparatus capacity of the dispersing machine . 8. When 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 wavelength is 320 to The manufacturing method according to any one of claims 1 to 7, wherein the minimum transmittance at 400 nm is 5% or less, and the average value of the transmittance at wavelengths 410 nm and 800 nm is 10% or more.