JPH11147036A - Aqueous dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion of inorganic particles having good dispersion stability without thickening and gelling even when stored for a long time, and without generating a sediment. . SOLUTION: It is formed by dispersing vapor-phase inorganic particles in an aqueous medium, and the dispersed inorganic particles have an average particle diameter of 0.05 to 0.05.
In the range of 0.9 μm and in saline
1 to 30 μm particles dispersed in 1% by weight and passing through the pores of the aperture tube were counted for 30 seconds.
Aqueous dispersion of not more than 000. However, it is assumed that the measuring machine is a Coulter Multitizer (2) type manufactured by Coulter Co., Ltd., and the size of the aperture of the aperture tube is 50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used for polishing slurries of cosmetics, paints, semiconductor wafers, etc.,
No problems such as thickening, gelling or sedimentation during storage,
It relates to an aqueous dispersion having excellent stability, for example, an aqueous colloid of inorganic particles.

[0002]

2. Description of the Related Art Conventionally, polishing slurries for cosmetics, paints, semiconductor wafers, and the like have been synthesized as high-purity raw materials having extremely few impurities by a gas phase method such as the fumed method (high-temperature flame hydrolysis method). Inorganic particles (hereinafter referred to as “fumed inorganic particles”) are used. However, since the fumed inorganic particles undergo strong secondary agglomeration, it is necessary to destroy and crush the agglomerates in water when producing an aqueous dispersion thereof. If the aggregates are insufficiently broken and disintegrated, and the number of coarse particles is large, the aqueous dispersion thickens over time during storage or gels and loses its fluidity, making it unusable. Also, there is a problem that the aggregate precipitates and separates during storage. Conventionally, as a method for producing an aqueous dispersion by breaking and crushing aggregates of fumed inorganic particles, a method using a high-speed stirring type dispersing apparatus such as a Waring blender or a high shear mixer (Japanese Patent Laid-Open No. 50112/1991). ) And a device combining a powder introduction mixing and dispersing machine such as a jet stream mixer and a toothed colloid mill / dissolver / skim stirrer (Nippon Aerosil Co., Ltd., Catalog No. 19, “Handling method of Aerosil”, page 38). ing. However, any of these methods has a problem that the aggregates cannot be sufficiently broken or broken, and a large number of coarse particles are present.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical problems, and the viscosity or gelation or sedimentation occurs due to thickening even when stored for a long time. An object of the present invention is to provide an aqueous dispersion of inorganic particles having good dispersion stability without causing any dispersion.

[0004]

The present invention relates to an aqueous dispersion obtained by dispersing inorganic particles synthesized by a gas phase method in an aqueous medium, wherein the dispersed inorganic particles have an average particle diameter of 0.0
The count value of 1 to 30 μm particles in the range of 5 to 0.9 μm and dispersed in physiological saline at 0.01% by weight and passing through the pores of the aperture tube for 30 seconds is 2000 or less. It is an aqueous dispersion. However, the measuring device of the count value is a Coulter Multitizer (2) type (type number is described in Roman numerals) of Coulter Co., Ltd., and the size of the aperture of the aperture tube is 50 μm. The average particle size is “LAZER PRACTICE ANALZER” manufactured by Otsuka Electronics Co., Ltd.
PAR-3). The dispersed inorganic particles of the present invention are composed of secondary particles or secondary particles and primary particles. If the average particle size of the inorganic particles after dispersion is less than 0.05 μm, the viscosity of the aqueous dispersion is too large and handling becomes difficult. If it exceeds 0.9 μm, the stability becomes poor and sedimentation occurs. The particle size can be controlled by selecting the type of raw material of the inorganic particles, the solid concentration at the time of kneading, and the like. Aqueous colloid (aqueous dispersion) of the present invention
Can be used, for example, for cosmetics, paints, coating agents, slurries for polishing semiconductor wafers, and the like.

[0005] 1. Counting with Coulter Multitizer. FIG. 1 shows the measurement principle of the Coulter Multitizer Type 2 (manufactured by Coulter Co., Ltd.). The Coulter Multitizer (2) type measures the number of slurry particles passing through an aperture (pores, openings) of an aperture tube within a predetermined time based on the value of current flowing between electrodes provided inside and outside the aperture tube. It is a device for counting. That is, when the slurry particles pass through the pores of the aperture tube,
The impedance of both electrodes changes according to the volume of the slurry particles, and this is observed as a change (pulse) in the current value flowing between both electrodes. The pulses are accumulated for each channel (size), and the particle size distribution is determined based on the accumulated pulses. The diameter of the slurry particles passing through the aperture is 2 to 60% of the aperture size (opening diameter). For example, when the aperture size is 50 μm,
Slurry particles of 1 to 30 μm will pass.

[0006] 2. Vapor phase inorganic particles. Inorganic particles synthesized by a gas phase method such as a fumed method (high-temperature flame hydrolysis method) or a nanophase technology company method (metal evaporation oxidation method) have a high purity and are therefore suitably used in the present invention. As the vapor-phase inorganic particles, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, antimony oxide,
Examples thereof include metal oxides such as chromium oxide, germanium oxide, vanadium oxide, tungsten oxide, iron oxide, and cerium oxide. Among them, particularly preferred are silicon oxide, aluminum oxide, titanium oxide and cerium oxide. The vapor phase inorganic particles to be dispersed are generally powders, and exist as aggregates (secondary particles) of small particles (primary particles). The average particle diameter of the primary particles is usually 0.005 to 1 μm.

[0007] 3. Example of distribution method. (A) Outline. The aqueous dispersion of the present invention, for example, the above-mentioned inorganic particles are added to an aqueous medium in a kneading tank of a kneader of a type in which a sub-rotating shaft is rotated by a main rotating shaft while a stirring blade is rotated by a sub-rotating shaft. And disperse them. The method of rotating the sub-rotation axis by the main rotation axis while rotating the stirring blade by the sub-rotation axis is generally called a planetary method.

(B) Planetary kneader. FIG. 2 schematically shows a planetary kneader, wherein (a) is a top view and (b) is a side view. As shown, kneading tank of planetary kneading machine
A stirring blade 11a that rotates around the sub-rotating shaft a in the direction of the arrow and a stirring blade 11b that rotates around the sub-rotating shaft b in the direction of the arrow are provided in 10, and these two sub-rotating shafts are provided. A main rotation axis c for rotating the axes a and b in the direction of the arrow is provided. That is, with the planetary kneader, the stirring blade rotates (rotates) around the auxiliary rotation shaft, and
This is a kneading machine in which the sub-rotating shaft rotates (revolves) around the main rotating shaft. Since the stirring blades 11a and 11b provided in this way move along a complicated trajectory, the fluid in the kneading tank is uniformly kneaded, the agglomerates are sufficiently separated, and as a result, a large amount of powder is removed in a relatively small amount. Can be efficiently dispersed in the liquid. In FIG. 2, the auxiliary rotation axis is a
2 and b, the number of auxiliary rotation shafts may be one or three or more. When a plurality of sub-rotating shafts are provided, the sub-rotating shafts may be provided at equal intervals or may not be at equal intervals. In FIG. 2, two stirring blades are provided as one set per one sub-rotating shaft.
One stirring blade may be provided, or three or more stirring blades may be provided as one set. In addition, a high-speed rotating blade is provided coaxially with the sub-rotating shaft of the stirring blade or on a separate axis from the sub-rotating shaft of the stirring blade.
The dispersing ability may be further improved. FIG. 2 shows a case where both the main rotation axis c and the sub rotation axes a and b rotate counterclockwise when viewed from above, but the rotation directions of the main rotation axis and the sub rotation axis are mutually changed. May be set in the opposite direction to change the trajectory of the movement of the stirring blade. FIG. 2 shows a case in which the stirring blades 11a and 11b are so-called twisted shapes that are curved and twisted between both ends.
As the shape of the stirring blade, the fluid in the kneading tank can be uniformly kneaded, and the aggregate can be sufficiently separated, and as a result,
Other shapes may be employed as long as a large amount of powder can be efficiently dispersed in a relatively small amount of liquid. Examples of the planetary kneader satisfying the above requirements include a kneader provided under the following name. For example, a universal mixing stirrer (Dalton Co., Ltd.), a universal mixer (Powrex Co., Ltd.), a KPM Power Mix (Kurimoto Steel Works, Ltd.), a planetary kneader mixer (Ashizawa Co., Ltd.), T.K. K. Hibis Dispers Mix (manufactured by Tokushu Kika Kogyo Co., Ltd.), Planetary Dispers (Asada Iron Works Co., Ltd.) and the like are preferably used. In particular, a planetary disper, which is a device combining a stirring blade that rotates and revolves, and a high-speed rotating blade (disper); K. Hibis Dispermix is preferable because a large amount of powder can be uniformly dispersed in a relatively small amount of liquid in a short time.

(C) Concentration at dispersion. The concentration at which the vapor phase inorganic particles (powder) are dispersed in the aqueous medium is 30 to 70.
%, Preferably 35 to 60% by weight, more preferably 40 to 50% by weight. When the solid concentration is 30% by weight or less, the dispersion efficiency is poor, so that a large amount of aggregates remain in the obtained aqueous dispersion (aqueous colloid), causing a problem of sedimentation / separation during storage or an increase in viscosity. It may gel. On the other hand, if the concentration is too high, such as 70% by weight or more, the load on the dispersing device is too large, causing a problem that the stirring operation is stopped, or if the stirring operation is forcibly continued in this state, excessive dispersion is caused. In some cases, a large amount of coarse particles of 10 μm or more are generated by aggregation.

(D) Addition method. It is desirable that the inorganic particles synthesized by the fumed method be dispersed in an aqueous medium while being added continuously or intermittently. If the required amount of powder is added from the beginning, not only is it difficult to uniformly disperse the powder, but also there is a problem that the load is too large and the stirrer stops. As a method for adding the powder, the powder is rapidly charged up to a solid content concentration of about 20% by weight, and then the powder is continuously or intermittently monitored so as not to be overloaded while monitoring the current value (load) of the kneader. It is good to add. Examples of the powder feeding apparatus include a method of conveying with a screw.

(E) Addition of alkali or acid. It is preferable to add an acid or an alkali to the above-mentioned dispersion, since the stability of the finally obtained aqueous colloid of inorganic particles (aqueous dispersion) is improved. When an acid is added, the pH of the aqueous colloid (aqueous dispersion) of inorganic particles obtained after final dilution is preferably in the range of 7 to 2. When an alkali is added, the pH of an aqueous colloid (aqueous dispersion) of inorganic particles obtained after final dilution is preferably in the range of 7 to 12. pH below 2 or pH 12
If it is higher, problems such as dissolution of the inorganic particles and aggregation of the particles occur. The acid or alkali may be added in any of the following steps: a method in which the acid or the alkali is added to the aqueous dispersion medium, a step in the course of adding the inorganic powder, a step in the course of the addition of the inorganic powder, a step in the kneading, and a step in the kneading. Preferably, during kneading or before dilution after kneading (the dilution will be described later). Addition during the kneading or before the dilution after the kneading can prevent the formation of aggregates due to the addition. Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid,
Organic acids such as acetic acid, phthalic acid, acrylic acid, methacrylic acid, crotonic acid, polyacrylic acid, maleic acid, and sorbic acid can be used. Preferably, monovalent acids such as hydrochloric acid, nitric acid and acetic acid are used. As the alkali, for example, inorganic bases such as potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonia, and amines such as ethylenediane, triethylamine, and piperazine can be used.

(F) Dilution etc. It is desirable that the aqueous dispersion (inorganic colloidal dispersion) obtained in the dispersion step be diluted after the kneading step. The degree of dilution depends on the type of dispersed inorganic particles and the solids concentration during kneading,
By diluting with an aqueous medium, it is desirable to lower the solid content concentration by about 5% by weight or more from the solid content concentration at the time of kneading. If the solid content concentration during the kneading step remains unchanged, handling is difficult due to the high viscosity, and further, there is a problem in that the viscosity further increases during storage and gelation occurs. As a method for dilution, a method in which an aqueous medium is directly charged into the kneader is preferable because it can be easily taken out from the kneader. After the kneading step, in order to further improve the uniformity, the aqueous dispersion of the present invention can be obtained by performing a dispersion treatment using another kneader or a dispersing device. In that case, for example, a Coreless high-speed stirring / dispersing machine, a homomixer, a high-pressure homogenizer, or a bead mill can be preferably used. The kneading machine, the dispersing device, and the powder feeding device used in the above-mentioned dispersing step include lining of polyurethane, Teflon, epoxy resin, etc., and zirconia in order to prevent metal contamination in the aqueous dispersion (inorganic colloid) as much as possible. It is preferable to apply a ceramic lining such as that described above to the liquid-contacting portion and powder-contacting portion such as the inner wall and the stirring blade to enhance the abrasion resistance.

(G) Another example of the apparatus used in the dispersion step. In addition to the above-mentioned planetary system, in the dispersion process, for example,
(B) A powder introduction mixing / dispersing machine (trade name: Jet Stream Mixer (Mitamura Riken Kogyo Co., Ltd.) etc.) that can directly disperse inorganic particles in an aqueous medium while sucking them by gas-phase method, (b)
A high-pressure homogenizer (trade name: Mantongaulin homogenizer (Doei Shoji Co., Ltd.)) that disperses fluid by collision, a belt rehomogenizer (Nippon Seiki Seisakusho Co., Ltd.), a microfluidizer (Mizuho Industry Co., Ltd.), a nanomizer ( Tsukishima Kikai Co., Ltd.), Genus PY (Hakusui Chemical Industry Co., Ltd.), a system organizer (Nippon BEE Co., Ltd.), an ultimateizer (Itochu Industrial Machinery Co., Ltd.) and the like can be used. Further, a dispersing machine such as a bead mill can also be used. As the material of the beads, for example, alkali-free glass, alumina, zircon, zirconia, titania, and silicon nitride are preferable.
In the distribution processing, one type of disperser may be used, or two or more types of dispersers may be used plural times. In addition to the planetary system, when using a device other than the planetary system in the dispersion process, in order to prevent metal contamination of the aqueous dispersion of inorganic particles as much as possible, lining such as polyurethane, Teflon, epoxy resin, or zirconia. As in the case of the above-mentioned planetary system device, it is preferable that a ceramic lining is applied to a liquid contact portion such as an inner wall or a stirring blade to increase abrasion resistance.

4. filtration. In order to sufficiently remove the coarse particles present in the aqueous dispersion of the inorganic particles of the present invention, it is preferable to further carry out a filtration treatment with a filter after the dispersion. As the filter, a filter of a filter back type (ISP) can be used in addition to a depth type depth cartridge filter (Advantech Toyosha, Nippon Pall, etc.). What is a depth filter?
The filter has a filter material in which the pore structure is coarse on the inlet side, fine on the outlet side, and finer continuously or stepwise from the inlet side to the outlet side. That is, since the filter medium is sufficiently thick (for example, 0.2 to 2 cm), the filter can collect a large amount of foreign substances from the fluid passing through the filter medium. For example, as shown in FIG. 3 (b), the pore structure is coarse on the fluid ingress (inlet) side and fine on the discharge (outlet) side.
In addition, the filter material is designed to have a thickness d which is designed to become finer continuously or stepwise (steps may be one step or two or more steps) from the entry side to the discharge side. As a result, among the coarse particles, relatively large particles are collected near the entry side, relatively small particles are collected near the discharge side, and as a whole, coarse particles are collected at each part in the thickness direction of the filter. You. As a result, there is an effect that the collection of the coarse particles is reliably performed, and the filter is hardly clogged, and the life of the filter can be extended. Desirably, as shown in FIG. 3 (b), the thickness of the fibers is designed to be thicker on the inflow (inlet) side of the fluid and thinner on the discharge (outlet) side, so that the porosity is reduced. A filter material that is substantially uniform between the entry side and the discharge side is used. Here, the porosity is the ratio of the porosity per unit cross-sectional area in a plane orthogonal to the direction in which the fluid passes. Since the porosity is substantially uniform as described above, the pressure loss during filtration is small, and the conditions for collecting coarse particles are substantially uniform in the thickness direction. Further, a relatively low pressure pump can be used. The depth type filter may be a cartridge type filter 201 having a hollow cylindrical shape as shown in FIG. 3 (a), and FIG. 4 (b)
A bag-type filter 202 as shown in FIG. In the case of the hollow cylindrical filter 201, there is an advantage that the thickness of the filter medium can be designed to a desired thickness. In the case of the bag type, the filter section should allow the fluid to pass from inside the bag to outside the bag.
200 (see FIG. 4 (a)).
There is an effect that the substance to be filtered can be removed together with the filter 202. Such a depth filter, for example,
By setting and using in the filter section 200 shown in FIG. 4 (a), coarse particles having a particle diameter exceeding 5 μm are removed from the dispersion in which the vapor-phase inorganic particles are added and dispersed in an aqueous medium. can do. FIG. 4A shows a dispersing machine 10.
After adding and dispersing the vapor-phase inorganic particles in the aqueous medium in 1 and storing this dispersion in the tank 102,
Pumped out of the filter unit 200 by the pump P to the filter unit 200, and the filter set in the filter unit 200.
After repeating the circulation of filtering through 201 (or 202), and returning to the tank 102 again via the valve V1, the coarse particles in the dispersion are sufficiently removed, and then the valve V1 is closed and the valve V2 is opened to open the coarse particles. The aqueous dispersion after removing the particles is placed in a tank 30.
Shows the system to store in 0. Although FIG. 4A shows a circulation system, a one-pass system may be used. In the case of the one-pass method, the tank may be pressurized by air pressure or the like instead of the pressurizing pump P to perform the filtering process. In addition, you may use combining a centrifugation method. Further, when a filter having a large pore structure is used in combination with the former stage as a pre-filter, clogging is harder to occur, and there is an effect that the life of the depth type filter can be extended.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION For each of the aqueous dispersions of Examples 1 to 5 described later and the aqueous dispersions of Comparative Examples 1 to 3 described below, a coulter in which the aperture size of the aperture tube at the particle size detecting portion is 50 μm. Multitizer ▲ 2 ▼
Using a mold (manufactured by Coulter Co., Ltd.),
The number of particles of ３０30 μm was measured. First, Isoton 2 (physiological saline solution manufactured by Coulter, Inc.) was added to the measuring cell for 10 minutes.
0 cc, a 20% by weight aqueous solution of potassium hydroxide in 0.1%
1 cc was added, and a blank measurement for determining the count number A was performed. The count number A is a count value of the number of particles passing through an aperture (aperture having an aperture size of 50 μm) of the aperture tube for 30 seconds. Next, 0.1 c of a slurry adjusted to 10% by weight (preparation of each product (aqueous dispersion) of Examples 1 to 5 and Comparative Examples 1 to 3) was added by a micropipette and stirred for 30 seconds. Thereafter, measurement for obtaining the count number B was performed. In this measurement, the aperture of the aperture tube (opening having a diameter of 50 μm) is measured in 30 seconds.
Is the count value of the number of particles passing through. Next, the net count number N (the Coulter counter value N) was determined as (count number B−count number A = net count number N).

The storage stability and scratch of each aqueous dispersion were evaluated in relation to the Coulter counter value N measured as described above. Table 1 shows the evaluation results. Here, the storage stability was evaluated by the presence or absence of a precipitate when stored at 25 ° C. As a result, as shown in Table 1, in each of the products of Examples 1 to 5 where the Coulter counter value N was 1000 or less (within a preferable range), no precipitate was observed even after 2 months or more, and the product was stored well. Demonstrated stability. On the other hand, when the Coulter counter value N is 200 out of the range of the present invention.
In each of the products of Comparative Examples 1 to 3 having 0 or more, a precipitate was observed within 7 days, and the result was that storage stability was lacking. In addition, the scratch is used as a lap master SFT as a polishing machine.
Using LM-15 having a platen diameter of 380 mm manufactured by the company, a pad IC1000 manufactured by Rodel Nitta was attached to the platen of the polishing machine, and a silicon wafer was mounted on the pad. Each of the products 1 to 3 (aqueous dispersion) was diluted to a concentration of 10% and polished for 30 minutes, and after polishing, the silicon wafer was washed and dried, and the surface was visually observed using a differential interference microscope. The presence or absence of surface defects (scratch) was examined. The polishing conditions were a processing pressure of 10
0 g / cm ² , platen rotation speed 30 rpm, abrasive supply 1
00 cc / min. As a result, as shown in Table 1, when each product of Examples 1 to 5 having a Coulter counter value N of 1000 or less was used as an abrasive, there was obtained a result that there was no scratch and the abrasive was suitable. On the other hand, when each of the products of Comparative Examples 1 to 3 having a Coulter counter value N of 2500 or more was used as an abrasive, a result was obtained in which there was a scratch and was not suitable as an abrasive.

1. Embodiment 1 FIG. Aerosil # 50 (fumed silica (silicon dioxide) manufactured by Nippon Aerosil Co., Ltd.)
Using a planetary kneader (trade name: TK Hibis Dispermix, HDM-3D-20, manufactured by Tokushu Kika Kogyo Co., Ltd.), 6 kg of ion-exchanged water with a twist blade in 6 kg of water The mixture was rotated at a rotation speed of 10 rpm and a sub-rotation shaft of 30 rpm, and continuously added over 30 minutes while kneading. After the addition, the kneading operation of rotating the sub-rotation axis of the twist blade at 30 rpm and the sub-rotation axis of the coreless high-speed rotary blade with a diameter of 80 mm at 2,000 rpm for an additional hour at a solid concentration of 50% by weight. The rotating dispersing process was simultaneously performed while rotating the main rotating shaft at 10 rpm, and continued for 60 minutes. Then 2
0.3108k of 0% by weight potassium hydroxide aqueous solution
g, the kneading operation of rotating the sub-rotation axis of the twist blade at 30 rpm, and the dispersing process of rotating the sub-rotation axis of the coreless high-speed rotary blade with a diameter of 80 mm at 2000 rpm, and rotating the main rotation axis at 10 rpm, respectively. The operation to be performed simultaneously was performed for 10 minutes. The obtained slurry was diluted with ion-exchanged water to obtain a 30% by weight aqueous colloid of silicon oxide (aqueous dispersion). This was further processed by a depth cartridge filter having a pore size of 5 μm to remove coarse particles. The obtained silicon dioxide aqueous dispersion has a volume-based average particle diameter of 0.20.
μm, pH was 10.6. The measured value N is 67
It was 0. Here, the average particle diameter is measured on a volume basis, but substantially the same result is obtained on a weight basis. 2. Embodiment 2. FIG. In Example 2, an aqueous colloid was obtained in the same manner as in Example 1, except that the concentration of the solid content at the time of kneading was 40% by weight. The volume-based average particle diameter of the obtained silicon dioxide aqueous dispersion was 0.25 μm, and the pH was 10.5. The measured value N was 530. 3. Embodiment 3 FIG. In Example 1, the point that the solid content concentration at the time of dispersion by kneading was set to 45% by weight, and the aqueous dispersion after dispersion by kneading was used as a high-pressure homogenizer equipped with a unit made of single crystal diamond (trade name)・ Genus P
Example 1 Example 1 was repeated except that the dispersion treatment was further performed using Y model PRO2-15 (manufactured by Hakusui Chemical Industry Co., Ltd.) and the depth cartridge filter treatment with a pore size of 5 μm was performed.
An aqueous colloid was obtained in the same manner as described above. The volume-based average particle diameter of the obtained silicon dioxide aqueous dispersion was 0.23 μm, and the pH was 10.6. The measured value N was 330. 4. Embodiment 4. FIG. An aqueous colloid was obtained in the same manner as in Example 3 except that a 20% by weight aqueous solution of potassium hydroxide was added to ion-exchanged water before Aerosil dispersion. The volume-based average particle diameter of the obtained silicon dioxide aqueous dispersion was 0.23 μm, and the pH was 10.6. The measured value N was 1,000. 5. Embodiment 5 FIG. In Example 1, Aerosil # 50
(9 kg of fumed silica (silicon dioxide) is mixed with a planetary kneader (trade name: TK Hibis Dispermix, H
Using a DM-3D-20, manufactured by Tokushu Kika Kogyo Co., Ltd.), in 9 kg of ion-exchanged water, rotate the twist blade with a main rotation shaft of 10 rpm and a sub rotation shaft of 30 rpm, and knead for 60 minutes. An aqueous colloid was obtained in the same manner as in Example 1, except that the aqueous colloid was continuously added. The volume-based average particle size of the obtained silicon dioxide aqueous dispersion is 0.22 μm, p
H was 10.6. The measured value N was 330.

6. Comparative Example 1 In Comparative Example 1, dispersion was performed only by the high-pressure method without using the kneading method or the filter treatment method. Here, the high-pressure method refers to treatment at 500 kg / cm ² using a high-pressure homogenizer (trade name: Genus PY Model PRO2-15 (manufactured by Shirasu Chemical Industry Co., Ltd.)) equipped with a unit made of single crystal diamond. That is, 8 kg of ion-exchanged water was weighed and measured in a 10-liter plastic container, and 2 kg of Aerosil # 50 (fumed silica (silicon dioxide)) was stirred with an acrylic resin rod to perform preliminary dispersion. After treating once at 500 kg / cm ² using a high-pressure homogenizer (trade name: Genus PY model PRO2-15 (manufactured by Shirasu Chemical Co., Ltd.)) equipped with a unit made of single crystal diamond, potassium hydroxide having a concentration of 20% by weight was used. 0.1036 kg of the aqueous solution was added, and further added with a high-pressure homogenizer.
This was repeated to obtain an aqueous dispersion of silicon dioxide. The obtained silicon dioxide aqueous dispersion has a volume-based average particle diameter of 0.25.
μm, pH was 10.6. The measured value N is 44
00. 7. Comparative Example 2. In Example 4, an aqueous dispersion of fumed silica was prepared by performing the same treatment as in Example 4 except that the high-pressure method was not performed and the filter treatment was not performed. The obtained silicon dioxide aqueous dispersion has a volume-based average particle diameter of 0.21 μm and a pH of 1
0.7. The measured value N was 50,000. 8. Comparative Example 3 In Example 5, an aqueous dispersion of fumed silica was prepared by performing the same treatment as in Example 5 except that the filter treatment was not performed.
The obtained silicon dioxide aqueous dispersion had a volume-based average particle diameter of 0.24 μm and a pH of 10.5. The measured value N was 2500.

[0019]

[Table 1]

[0020]

The aqueous dispersion of vapor-phase inorganic particles of the present invention has good dispersion stability without gelling due to thickening even when stored for a long period of time and no sediment is generated. It is.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the measurement principle of a Coulter Multitizer (2) type.

FIG. 2 shows a planetary kneader, wherein (a) is a top view,
(B) is a side view.

3A is a perspective view schematically illustrating a depth-type filter cartridge having a hollow cylindrical shape, and FIG. 3B is a schematic view illustrating a hole structure and a transition diameter in a thickness direction of the depth-type filter.

4A is a configuration diagram illustrating an example of a system that performs filtration using the depth filter of FIG. 2, and FIG. 4B is a perspective view schematically illustrating a depth filter of a bag tablet.

[Explanation of symbols]

 10 kneading tank of planetary kneader a sub-rotating shaft 11a stirring blade 11a b sub-rotating shaft 11b stirring blade c main rotating shaft

Claims (2)

[Claims] An aqueous dispersion obtained by dispersing inorganic particles synthesized by a gas phase method in an aqueous medium, wherein the dispersed inorganic particles have an average particle size of 0.05 to 0.9 μm.
, Which are dispersed in physiological saline at 0.01% by weight and pass through the pores of the aperture tube.
An aqueous dispersion in which a value obtained by counting 0 μm particles for 30 seconds is 2000 or less. However, the measuring machine of the count value is Coulter Co., Ltd. Coulter Multi-Tiser (2) type,
The aperture size of the pores of the aperture tube is 50 μm. 2. An aqueous dispersion, wherein gas-phase inorganic particles are added to an aqueous medium in a kneading tank of a kneader of a system in which a stirring blade is rotated by a sub-rotation shaft while a sub-rotation shaft is rotated by a main rotation shaft. The aqueous dispersion according to claim 1, which is obtained by dispersing the aqueous dispersion.