JP3849261B2 - Method for producing aqueous dispersion - Google Patents

Description

【００２０】
【発明の効果】
本発明の製造方法により製造した無機粒子の水性分散体は、長時間保管しておいても増粘してゲル化したり、沈降物が発生したりすることが無く分散安定性が良好である。
【図面の簡単な説明】
【図１】コールターマルチタイザー▲２▼型の測定原理を示す説明図。
【図２】遊星方式の混練機を示し、（ａ）は上面図、（ｂ）は側面図。
【図３】（ａ）は中空円筒形状のデプス型のフィルターカートリッジを模式的に示す斜視図、（ｂ）はデプス型フィルターの厚み方向の孔構造と遷移径を説明する模式図。
【図４】（ａ）は図２のデプス型フィルターを用いて濾過するシステムの一例を示す構成図、（ｂ）は袋錠のデプス型フィルターを模式的に示す斜視図。
【符号の説明】
１０ 遊星方式の混練機の混練槽
ａ 副回転軸
１１ａ 攪拌ブレード11a
ｂ 副回転軸
１１ｂ 攪拌ブレード
ｃ 主回転軸[0001]
BACKGROUND OF THE INVENTION
The present invention can be used for polishing slurries for cosmetics, paints, semiconductor wafers, etc., and has no problems such as thickening, gelation or sedimentation during storage, and is an aqueous dispersion excellent in stability, such as inorganic Aqueous colloid of particlesManufacturing methodAbout.
[0002]
[Prior art]
Conventionally, for polishing slurries such as cosmetics, paints, and semiconductor wafers, inorganic particles synthesized by a vapor phase method such as the fumed method (high-temperature flame hydrolysis method) as a high-purity raw material with very few impurities (hereinafter referred to as “ "Fumed inorganic particles"). However, since the fumed inorganic particles are severely secondary agglomerated, it is necessary to break and crush the agglomerates in water when producing the aqueous dispersion. When there are many coarse particles due to insufficient destruction and crushing of the aggregates, the problem is that the aqueous dispersion thickens over time during storage or gels and loses its fluidity so that it cannot be used. In addition, there is a problem that aggregates are precipitated and separated during storage.
Conventionally, as a method for producing an aqueous dispersion by breaking and crushing the aggregates of fumed inorganic particles, a method using a high-speed stirring type dispersion device such as a Waring blender or a high shear mixer (Japanese Patent Laid-Open No. 3-50112). ), And a device incorporating 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 “Aerosil Handling Method” P38) is known. ing. However, in any of the methods, there is a problem that the aggregates cannot be sufficiently broken and crushed and a large number of coarse particles are present.
[0003]
[Problems to be solved by the invention]
The present invention has been made against the background of the above-mentioned conventional technical problems, and has good dispersion stability without thickening and gelling or generating sediment even after storage for a long time. Aqueous dispersion of inorganic particlesManufacturing methodThe purpose is to provide.
[0004]
[Means for Solving the Problems]
  The production method of the present invention includes the following [1] to [8].
[1] While rotating the stirring blade by the auxiliary rotating shaftTheRotate the sub rotation shaft by the main rotation shaftHaveRuPlanetInorganic particles synthesized by the vapor phase method in the aqueous medium in the kneading tank of the kneading machineContinuously or intermittently while monitoring the kneader to avoid overloadingAdd solid content concentrationBut30% to 70% by weightFirst dispersion step to obtain an aqueous dispersion in the range,
  The aqueous dispersion after the first dispersion step is rotated while the stirring blade is rotated by the sub-rotating shaft, the sub-rotating shaft is rotated by the main rotating shaft, and the high-speed rotating blade is rotated by the sub-rotating shaft. A second dispersion step of further dispersing in a kneading tank of a planetary kneader rotating a rotation shaft by the main rotation shaft over a longer time than the first dispersion step;
  A dilution step in which the aqueous dispersion after the second dispersion step is diluted with an aqueous medium to reduce the solid content concentration by 5% by weight or more;
  The aqueous dispersion after the dilution step is designed so that the pore structure of the filter medium is rough on the inlet side, finer on the outlet side, and finer continuously or stepwise from the inlet side to the outlet side. A filtration step of filtering using a depth type filter,
  By carrying out in order,The inorganic particles have an average particle diameter in the range of 0.05 to 0.9 μm, and are dispersed in physiological saline at 0.01% by weight and pass through pores having an aperture tube diameter of 50 μm. Manufacture characterized in that an aqueous dispersion having a count value of 2000 or less obtained by detecting 30 μm particles based on a change in current value flowing between electrodes provided inside and outside the aperture tube is obtained. Method.
[2]In the above [1],
  An acid or an alkali is added during the second dispersion step;
  The manufacturing method characterized by the above-mentioned.
[3]In the above [1] or [2],
  Performing a third dispersion step using a high-pressure homogenizer for further dispersing by causing the aqueous dispersion after the dilution step to flow and collide, and then performing the filtration step;
  The manufacturing method characterized by the above-mentioned.
[4]In the above [1],
  Prior to the first dispersion step, acid or alkali is added to the aqueous medium in the kneading tank of the planetary kneader,
  Performing a third dispersion step using a high-pressure homogenizer for further dispersing by causing the aqueous dispersion after the dilution step to flow and collide, and then performing the filtration step;
  The manufacturing method characterized by the above-mentioned.
[5]In any one of the above [1] to [4],
  Performing the first dispersion step over at least 30 minutes and performing the second dispersion step over at least 70 minutes;
  The manufacturing method characterized by the above-mentioned.
[6]In any one of the above [1] to [5]
  Carrying out the first dispersion step so as to obtain an aqueous dispersion having a solids concentration in the range of 35% to 60% by weight;
  The manufacturing method characterized by the above-mentioned.
[7] In any one of [1] to [6],
  The inorganic particles are fumed silica particles.
  The manufacturing method characterized by the above-mentioned.
[8] In any one of [1] to [7],
  By carrying out the steps in order, the average particle diameter of the inorganic particles is in the range of 0.05 to 0.9 μm, and the aperture tube has a diameter of 50 μm by being dispersed in physiological saline at 0.01% by weight. 1 to 30 μm particles passing through the pores are detected based on the change in the current value flowing between the electrodes provided inside and outside the aperture tube and counted for 30 seconds. A production method characterized in that an aqueous dispersion having a viscosity of 1000 or less is obtained.
  The average particle diameter was measured using “LAZER PRACTICE ANALTZER PAR-3” manufactured by Otsuka Electronics Co., Ltd.
  The inorganic particles after dispersion by the production method of the present invention are composed of secondary particles or secondary particles and primary particles.
  When 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 kind of inorganic particle raw material, the solid content concentration during kneading, and the like.
  The aqueous colloid (aqueous dispersion) produced by the production method of the present invention can be used, for example, in cosmetics, paints, coating agents, semiconductor wafer polishing slurries and the like.
[0005]
1. Counting with Coulter Multitizer.
FIG. 1 shows the measurement principle of Coulter Multitizer (2) type (manufactured by Coulter Co., Ltd.). The Coulter Multitizer type (2) is based on the number of slurry particles that pass through the aperture (pores, openings) of the aperture tube within a predetermined time based on the value of the current flowing between the 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 impedances of both electrodes change according to the volume of the slurry particles, and this is observed as a change (pulse) in the current value flowing between the two electrodes. This pulse is accumulated for each channel (size), and the particle size distribution is obtained based on this. 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, 1 to 30 μm of slurry particles pass through.
[0006]
2. Gas phase inorganic particles.
Inorganic particles synthesized by a gas phase method such as the fumed method (high-temperature flame hydrolysis method) or the nanophase technology method (metal evaporation oxidation method) have high purity, and thus are suitably used in the present invention. Examples of vapor phase inorganic particles include metal oxides such as silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, antimony oxide, chromium oxide, germanium oxide, vanadium oxide, tungsten oxide, iron oxide, and cerium oxide. Of these, silicon oxide, aluminum oxide, titanium oxide, and cerium oxide are particularly preferable.
The vapor phase inorganic particles used for dispersion are generally powders and exist as aggregates (referred to as secondary particles) of small particles (referred to as primary particles). The average particle diameter of the primary particles is usually 0.005 to 1 μm.
[0007]
3. Examples of distribution methods.
(A) Overview.
waterFor example, the above-mentioned inorganic particles are added to and dispersed in an aqueous medium in a kneading tank of a kneader of a type in which the auxiliary rotating shaft is rotated by the main rotating shaft while the stirring blade is rotated by the auxiliary rotating shaft. ByManufacturebe able to. A method of rotating the sub-rotation shaft by the main rotation shaft while rotating the stirring blade by the sub-rotation shaft is generally called a planetary method.
[0008]
(B) Planetary kneader.
FIG. 2 schematically shows a planetary kneader, where (a) is a top view and (b) is a side view. As shown in the figure, in the kneading tank 10 of the planetary kneader, the stirring blade 11a that rotates around the sub-rotating shaft a in the direction of the arrow, and the stirring blade 11b that rotates around the sub-rotating shaft b in the direction of the arrow. And a main rotation shaft c for rotating these two auxiliary rotation shafts a and b in the direction of the arrow. That is, the planetary kneader is a kneader configured such that the stirring blade rotates (rotates) around the sub-rotating shaft, and the sub-rotating shaft rotates (revolves) around the main rotating shaft. is there.
Since the stirring blades 11a and 11b provided in this manner move along a complicated trajectory, the fluid in the kneading tank is uniformly kneaded and the aggregates are sufficiently divided, and as a result, a large amount of powder is relatively small. It becomes possible to disperse efficiently in the liquid.
FIG. 2 shows the case where there are two sub-rotating shafts a and b, but there may be one sub-rotating shaft or three or more sub-rotating shafts. In addition, when a plurality of sub-rotation shafts are provided, the sub-rotation shafts may be provided at equal intervals or not at equal intervals.
In FIG. 2, two stirring blades are provided as one set per sub-rotating shaft. However, one stirring blade may be provided, or three or more stirring blades may be provided as one set. . Further, a high-speed rotary blade may be provided coaxially with the sub-rotating shaft of the stirring blade or on a different shaft from the sub-rotating shaft of the stirring blade, and the ability to separate and disperse the aggregates may be further improved by the high-speed rotating blade.
FIG. 2 shows the case where the main rotation shaft c and the sub rotation shafts a and b both rotate counterclockwise when viewed from above. However, the rotation directions of the main rotation shaft and the sub rotation shaft are mutually different. The direction of the movement of the stirring blade may be changed by setting the direction to the opposite direction.
FIG. 2 shows a so-called twisted shape in which the stirring blades 11a and 11b are curved and twisted between both end portions. The shape of the stirring blade is such that the fluid in the kneading tank is uniform. Other shapes may be adopted as long as the shape can be kneaded and the aggregate can be sufficiently divided, and as a result, 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 (Powrec Co., Ltd.), KPM Power Mix (Kurimoto Corporation), a planetary kneader mixer (Ashizawa Co., Ltd.), K. Hibis Disper mix (manufactured by Tokushu Kika Kogyo Co., Ltd.), planetary disper (Asada Tekko Co., Ltd.) and the like are preferably used. In particular, planetary dispersers, which are a combination of agitation blades that rotate and revolve, and high-speed rotating blades (dispers), K. Hibisdisper mix is preferable because a large amount of powder can be uniformly dispersed in a relatively small amount of liquid in a short time.
[0009]
(C) Concentration at dispersion.
The concentration at which the vapor phase inorganic particles (powder) are dispersed in the aqueous medium is 30 to 70% by weight, preferably 35 to 60% by weight, and more preferably 40 to 50% by weight. Since the dispersion efficiency is poor at a solid content concentration of 30% by weight or less, a large amount of agglomerates remain in the obtained aqueous dispersion (aqueous colloid), causing problems such as sedimentation and separation during storage, and thickening. It may gel. On the other hand, if the concentration is too high, such as 70% by weight or more, the load of the dispersing device is too large, causing a problem that the stirring operation stops, or if the stirring operation is forcibly continued in that state, excessive dispersion will occur. In some cases, a large amount of coarse particles of 10 μm or more are generated due to aggregation.
[0010]
(D) Adding method.
The inorganic particles synthesized by the fumed method are desirably dispersed in an aqueous medium while being continuously or intermittently added. When a necessary amount of powder is added from the beginning, not only is it difficult to disperse uniformly, but there is also a problem that the stirrer stops due to an excessive load. As a method of addition, the solid content concentration is rapidly charged up to about 20% by weight, and thereafter the powder is continuously or intermittently monitored so as not to overload while monitoring the current value (load) of the kneader. It is good to add. Examples of the powder input device include a method of conveying with a screw.
[0011]
(E) Addition of alkali or acid.
It is preferable to add an acid or an alkali to the above-mentioned dispersion because stability of the aqueous colloid (aqueous dispersion) of the finally obtained inorganic particles is improved. When the acid is added, the pH of the aqueous colloid (aqueous dispersion) of the inorganic particles obtained after the final dilution is preferably in the range of 7 to 2. Moreover, when adding an alkali, the pH of the aqueous colloid (aqueous dispersion) of the inorganic particle obtained after the final dilution is preferably in the range of 7-12. When the pH is lower than 2 or the pH is higher than 12, there arises a problem that the inorganic particles are dissolved or the particles are aggregated.
The timing of addition of the acid or alkali may be any of the method of adding in advance to the aqueous dispersion medium, the process of adding the inorganic powder, the process of adding the inorganic powder, the process of kneading, and the process of kneading. Preferably, in the middle of kneading or before dilution after kneading (dilution will be described later). When added during the kneading or at the time before dilution after kneading, the generation of aggregates due to the addition can be prevented.
Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as acetic acid, phthalic acid, acrylic acid, methacrylic acid, crotonic acid, polyacrylic acid, maleic acid, and sorbic acid. Can be used. Preferred are hydrochloric acid, nitric acid and acetic acid which are monovalent acids.
Examples of the alkali that can be used include inorganic bases such as potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonia, and amines such as ethylenedian, triethylamine, and piperazine.
[0012]
(F) Dilution, etc.
The aqueous dispersion (inorganic colloidal dispersion) obtained in the dispersion step is preferably diluted after the kneading step. The degree of dilution varies depending on the type of dispersed inorganic particles and the solid content concentration during kneading, but by diluting with an aqueous medium, the solid content concentration is reduced by about 5% by weight or more from the solid content concentration during kneading. It is desirable. If the solid content concentration in the kneading step is still high, the viscosity is high, so that it is difficult to handle, and there is a problem of further thickening or gelation during storage. As a method for diluting, a method in which an aqueous medium is directly fed into a kneader is preferable because it becomes easier to take out from the kneader. After the kneading step, the aqueous dispersion of the present invention can also be obtained by carrying out a dispersion treatment using another kneader or a dispersing device in order to further improve the uniformity. In that case, for example, a Coreless type high-speed stirring disperser, a homomixer, a high-pressure homogenizer, or a bead mill can be preferably used.
In addition, as a kneading machine, a dispersing device, and a powder charging device used in the above-described dispersion process, in order to prevent metal contamination in the aqueous dispersion (inorganic colloid) as much as possible, lining of polyurethane, Teflon, epoxy resin, etc., zirconia It is preferable to apply a ceramic lining such as an inner wall or a stirring blade to a wetted part or a wetted part to improve wear resistance.
[0013]
(G) Other examples of apparatuses used in the dispersion step.
In addition to the planetary system described above, in the dispersion process, for example, (a) a powder introduction mixing and dispersing machine (trade name: Jetstream Mixer (Mitamura), which can directly disperse vapor phase inorganic particles in an aqueous medium while sucking them. Riken Kogyo Co., Ltd.), (b) High-pressure homogenizer (product name: Manton Gaurin homogenizer (Doei Shoji Co., Ltd.), Belt Rehomogenizer (Nippon Seiki Seisakusho Co., Ltd.), Micro Fluidizer (Mizuho Kogyo Co., Ltd.), Nanomizer (Tsukishima Kikai Co., Ltd.), Genus PY (Shiramizu Chemical Co., Ltd.), System Organizer (Japan EE Co., Ltd.), Ultimateizer (ITOCHU INDUSTRY CO., LTD.) Etc.) can be used. A disperser such as a bead mill can also be used. As the material for the beads, for example, alkali-free glass, alumina, zircon, zirconia, titania, and silicon nitride are preferable.
In the dispersion processing, one type of disperser may be used, or two or more types of dispersers may be used a plurality of times. In addition to the planetary system, when using a non-planetary system in the dispersion process, in order to prevent metal contamination of the aqueous dispersion of inorganic particles as much as possible, lining of polyurethane, Teflon, epoxy resin, etc., zirconia, etc. As in the case of the above-mentioned planetary system, it is preferable to apply ceramic lining to the wetted parts such as the inner wall and the stirring blade to improve wear resistance.
[0014]
4). filtration.
Of the present inventionIn the manufacturing method,In order to sufficiently remove the coarse particles present in the aqueous dispersion of inorganic particles, it is preferable to further perform filtration with a filter after the dispersion. As the filter, in addition to a depth type depth cartridge filter (Advantech Toyo Co., Ltd., Nippon Pole Co., Ltd.), a filter back type (ISP Co.) filter can be used.
The depth type filter is a filter in which the pore structure of the filter medium is rough on the inlet side, finer on the outlet side, and becomes finer continuously or stepwise from the inlet side toward 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 matters from the fluid passing through the filter medium.
For example, as shown in FIG. 3B, the pore structure is rough on the intrusion (inlet) side of the fluid, finer on the discharge (outlet) side, and continuously or stepwise from the intrusion side to the discharge side. The filter medium has a thickness d designed to be finer (the number of steps may be one or two or more). As a result, relatively large particles of coarse particles are collected near the intrusion 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. The As a result, it is possible to reliably collect coarse particles and to prevent the filter from being clogged and to prolong its life.
Desirably, as shown in FIG. 3 (b), the fiber thickness is designed to be thicker on the fluid ingress (inlet) side and thinner on the outlet (outlet) side, so that the porosity is reduced. A filter medium that is substantially uniform between the intrusion side and the discharge side is used. Here, the porosity is the ratio of the void per unit cross-sectional area in a plane orthogonal to the fluid passage direction. Thus, since the porosity is substantially uniform, the pressure loss at the time of filtration becomes small, and the collection conditions of coarse particles become substantially uniform in the thickness direction. Furthermore, a relatively low pressure pump can be used.
The depth type filter may be a hollow cylindrical cartridge type filter 201 as shown in FIG. 3A or a bag type filter 202 as shown in FIG. 4B. 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, since the fluid is provided in the filter unit 200 (see FIG. 4A) so that the fluid passes from the inside of the bag to the outside of the bag, the object to be filtered can be removed together with the filter 202 at the time of replacement. There is an effect.
For example, by using such a depth filter set in the filter unit 200 shown in FIG. 4 (a), from the dispersion in which the vapor phase inorganic particles are added and dispersed in the aqueous medium, Coarse particles having a particle diameter exceeding 5 μm can be removed.
FIG. 4A shows a case where vapor phase inorganic particles are added and dispersed in an aqueous medium in a disperser 101, the dispersion is stored in a tank 102, then sent out from the tank 102 and filtered by a pump P. After being filtered by the filter 201 (or 202) set in the filter unit 200 and returned to the tank 102 again through the valve V1, the coarse particles in the dispersion are sufficiently removed. Then, the system is shown in which the valve V1 is closed and the valve V2 is opened to store the aqueous dispersion after removal of coarse particles in the tank 300. In FIG. 4A, a circulation system is shown, but a one-pass system may be used. Further, in the case of the single pass method, instead of the pressurizing pump P, the tank may be pressurized with air pressure or the like and filtered.
A centrifugal separation method may be used in combination. Further, when a filter having a large pore structure is combined in the previous stage and used as a pre-filter, it becomes more difficult to clog, and there is an effect that the life of the depth filter can be extended.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
For each of the aqueous dispersions of Examples 1 to 5 to be described later and the aqueous dispersions of Comparative Examples 1 to 3 to be described later, Coulter Multitizer (2) type in which the aperture size of the aperture tube of the particle size detection portion was 50 μm ( Using Coulter Co., Ltd., the number of particles of 1 to 30 μm was measured as follows.
First, 100 cc of Isoton 2 (saline solution manufactured by Coulter Co., Ltd.) and 0.1 cc of a 20 wt% potassium hydroxide aqueous solution were added to the measurement cell, and blank measurement was performed to determine the count number A. The count number A is a count value of the number of particles passing through the aperture of the aperture tube (opening having a diameter of 50 μm) for 30 seconds.
Next, 0.1 c of slurry adjusted to 10 wt% (prepared products of each of Examples 1 to 5 and Comparative Examples 1 to 3 (aqueous dispersion)) was added with a micropipette and stirred for 30 seconds. Then, the measurement which calculates | requires the count number B was performed. This measurement is a count value of the number of particles passing through the aperture of the aperture tube (opening having a diameter of 50 μm) in 30 seconds.
Next, the net count number N (Coulter counter value N) is
(Count B-Count A = Net Count N)
As sought.
[0016]
The storage stability and scratch of each aqueous dispersion were evaluated in relation to the Coulter counter value N measured as described above. The evaluation results are shown in Table 1.
Here, the storage stability was evaluated by the presence or absence of precipitates when stored at 25 ° C. As a result, as shown in Table 1, in each of the products of Examples 1 to 5 having a Coulter counter value N of 1000 or less (within a preferable range), no precipitate was observed even after 2 months or more, and good storage was achieved. Showed stability. On the other hand, in each of the products of Comparative Examples 1 to 3 having a Coulter counter value N of 2000 or more outside the range of the present invention, precipitates were observed within 7 days, and the storage stability was lacking.
Scratch uses LM-15 with a 380 mm surface plate diameter manufactured by Lapmaster SFT as a polishing machine, and a pad IC 1000 manufactured by Rodel Nitta is attached to the surface plate of the polishing machine, and a silicon wafer is attached to the pad. Then, each product (aqueous dispersion) of Examples 1 to 5 and Comparative Examples 1 to 3 was diluted to a concentration of 10% and polished for 30 minutes, and after polishing, the silicon wafer was washed and dried to obtain differential interference. The surface was visually observed using a microscope, and the presence or absence of surface defects (scratches) was examined. The polishing conditions are a processing pressure of 100 g / cm.²The rotation speed of the platen was 30 rpm, and the abrasive supply rate was 100 cc / min. As a result, as shown in Table 1, when each of the products of Examples 1 to 5 having a Coulter counter value N of 1000 or less was used as an abrasive, there was no scratch and it was suitable as an abrasive. On the other hand, when each product of Comparative Examples 1 to 3 having a Coulter counter value N of 2500 or more was used as an abrasive, there was a result that there was a scratch and it was not suitable as an abrasive.
[0017]
1. Example 1.
Aerosil # 50 (fumed silica (silicon dioxide) 6 kg manufactured by Nippon Aerosil Co., Ltd.) is mixed with a planetary kneader (trade name: TK Hibis Disper Mix, HDM-3D-20, Special Machine Industries Co., Ltd.) The twist blade was rotated at 10 rpm and the sub-rotation shaft 30 rpm in ion exchange water 6 kg, and continuously added over 30 minutes while kneading. A kneading operation in which the sub-rotating shaft of the twisting blade is rotated at 30 rpm in a state where the solid content concentration is 50% by weight, and a disper treatment in which the sub-rotating shaft of the coreless high-speed rotating blade having a diameter of 80 mm is rotated at 2000 rpm, respectively. It was carried out simultaneously while rotating the main rotating shaft at 10 rpm, and continued for 60 minutes.
Thereafter, 0.3108 kg of 20 wt% potassium hydroxide aqueous solution was added, the kneading operation for rotating the auxiliary rotating shaft of the twist blade at 30 rpm, and the auxiliary rotating shaft of the coreless high-speed rotary blade having a diameter of 80 mm were rotated at 2000 rpm. The operation of simultaneously performing the disper treatment to be performed while rotating the main rotating shaft at 10 rpm was performed for 10 minutes.
The obtained slurry was diluted with ion-exchanged water to obtain an aqueous colloid (aqueous dispersion) of silicon oxide having a concentration of 30% by weight. This was further subjected to a depth cartridge filter treatment with a pore size of 5 μm to remove coarse particles.
The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.20 μm and a pH of 10.6. The measured value N was 670. Here, the average particle diameter is measured on a volume basis, but substantially the same result is obtained on a weight basis.
2. Example 2
In Example 2, an aqueous colloid was obtained in the same manner as in Example 1 except that the solid content concentration during kneading was 40% by weight. The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.25 μm and a pH of 10.5. The measured value N was 530.
3. Example 3 FIG.
In Example 1, the solid content concentration at the time of dispersion by kneading was 45% by weight, and the aqueous dispersion after dispersion by kneading was treated with a high-pressure homogenizer (trade name) having a unit made of single crystal diamond. An aqueous colloid was obtained in the same manner as in Example 1 except that the dispersion treatment was further performed using Genus PY model PRO2-15 (manufactured by Hakusui Chemical Co., Ltd.) and the depth cartridge filter treatment with a pore size of 5 μm was further performed. The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.23 μm, a pH of 10.6, and a measured value N of 330.
4). Example 4
In Example 3, an aqueous colloid was obtained in the same manner as in Example 3 except that a 20% by weight aqueous potassium hydroxide solution was added to ion-exchanged water before the dispersion of Aerosil. The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.23 μm and a pH of 10.6. The measured value N was 1000.
5). Example 5 FIG.
In Example 1, Aerosil # 50 (fumed silica (silicon dioxide) 9 kg was mixed with a planetary kneader (trade name: TK Hibis Disper Mix, HDM-3D-20, Special Machine Industries Co., Ltd.) Except that the twisting blade was rotated at 10 rpm and the auxiliary rotating shaft 30 rpm in the ion exchange water 9 kg and continuously added over 60 minutes while kneading. A volume-based average particle diameter of the obtained silicon dioxide aqueous dispersion was 0.22 μm, pH was 10.6, and measured value N was 330.
[0018]
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 processing method. The high-pressure method referred to here is 500 kg / cm using a high-pressure homogenizer (trade name: Genus PY model PRO2-15 (manufactured by Hakusui Chemical Co., Ltd.)) equipped with a unit made of single crystal diamond.²It means processing with.
That is, 8 kg of ion-exchanged water was measured in a 10-liter plastic container, and 2 kg of Aerosil # 50 (fumed silica (silicon dioxide)) was stirred with an acrylic resin rod for preliminary dispersion. Next, 500 kg / cm using a high-pressure homogenizer (trade name: Genus PY model PRO2-15 (manufactured by Hakusui Chemical Co., Ltd.)) equipped with a unit made of single crystal diamond.²Then, 0.1036 kg of a 20 wt% aqueous potassium hydroxide solution was added, and further treated once with a high-pressure homogenizer to obtain an aqueous silicon dioxide dispersion.
The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.25 μm and a pH of 10.6. The measured value N was 4400.
7). Comparative Example 2
In Example 4, an attempt was made to prepare an aqueous dispersion of fumed silica by carrying out the same treatment as in Example 4 except that the high-pressure method was not carried out and the filter treatment was not carried out.
The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.21 μm and a pH of 10.7. The measured value N was 50000.
8). Comparative Example 3
In Example 5, except for not performing the filter treatment, an aqueous dispersion of fumed silica was prepared by the same treatment as in Example 5.
The obtained silicon dioxide aqueous dispersion had a volume-based average particle size of 0.24 μm and a pH of 10.5. The measured value N was 2500.
[0019]
[Table 1]

[0020]
【The invention's effect】
Of the present inventionManufactured by manufacturing methodThe aqueous dispersion of inorganic particles has good dispersion stability without thickening and gelling or generating precipitates even when stored for a long time.
[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 kneading machine, in which (a) is a top view and (b) is a side view.
FIG. 3A is a perspective view schematically illustrating a hollow cylindrical depth type filter cartridge, and FIG. 3B is a schematic diagram illustrating a hole structure and a transition diameter in the thickness direction of the depth type filter.
4A is a configuration diagram showing an example of a system for filtering using the depth type filter of FIG. 2, and FIG. 4B is a perspective view schematically showing a depth filter of a bag tablet.
[Explanation of symbols]
10 Kneading tank of planetary kneading machine
a Sub-rotating shaft
11a Stirring blade 11a
b Secondary shaft
11b Stirring blade
c Main shaft

Claims (8)

Stirring blades in an aqueous medium in the kneading tank kneader Tei Ru planetary system is rotated by the main rotating shaft the auxiliary rotary shaft while rotating the auxiliary rotary shaft, the kneader inorganic particles synthesized by gas phase method A first dispersion step in which an aqueous dispersion having a solid content concentration in the range of 30% by weight to 70% by weight is added continuously or intermittently while monitoring to prevent overloading .
The aqueous dispersion after the first dispersion step is rotated while the stirring blade is rotated by the sub-rotating shaft, the sub-rotating shaft is rotated by the main rotating shaft, and the high-speed rotating blade is rotated by the sub-rotating shaft. A second dispersion step of further dispersing in a kneading tank of a planetary kneader rotating a rotation shaft by the main rotation shaft over a longer time than the first dispersion step;
A dilution step in which the aqueous dispersion after the second dispersion step is diluted with an aqueous medium to reduce the solid content concentration by 5% by weight or more;
The aqueous dispersion after the dilution step is designed so that the pore structure of the filter medium is rough on the inlet side, finer on the outlet side, and finer continuously or stepwise from the inlet side to the outlet side. A filtration step of filtering using a depth type filter,
Are carried out in order, the average particle size of the inorganic particles is in the range of 0.05 to 0.9 μm, and the aperture tube has a diameter of 50 μm dispersed in physiological saline at 0.01% by weight. An aqueous dispersion in which 1 to 30 μm particles passing through the pores are detected based on a change in current value flowing between electrodes provided inside and outside the aperture tube and counted for 30 seconds is 2000 or less. The manufacturing method characterized by obtaining. In claim 1,
An acid or an alkali is added during the second dispersion step;
The manufacturing method characterized by the above-mentioned. In claim 1 or claim 2,
Performing a third dispersion step using a high-pressure homogenizer for further dispersing by causing the aqueous dispersion after the dilution step to flow and collide, and then performing the filtration step;
The manufacturing method characterized by the above-mentioned. In claim 1,
Prior to the first dispersion step, acid or alkali is added to the aqueous medium in the kneading tank of the planetary kneader,
Performing a third dispersion step using a high-pressure homogenizer for further dispersing by causing the aqueous dispersion after the dilution step to flow and collide, and then performing the filtration step;
The manufacturing method characterized by the above-mentioned. In any one of Claims 1-4,
Performing the first dispersion step over at least 30 minutes and performing the second dispersion step over at least 70 minutes;
The manufacturing method characterized by the above-mentioned. In any one of Claims 1-5,
Carrying out the first dispersion step so as to obtain an aqueous dispersion having a solids concentration in the range of 35% to 60% by weight;
The manufacturing method characterized by the above-mentioned. In any one of Claims 1-6,
The inorganic particles are fumed silica particles.
The manufacturing method characterized by the above-mentioned. In any one of Claims 1-7,
By carrying out the steps in order, the average particle diameter of the inorganic particles is in the range of 0.05 to 0.9 μm, and the aperture tube has a diameter of 50 μm by being dispersed in physiological saline at 0.01% by weight. An aqueous dispersion in which 1 to 30 μm particles passing through the pores are detected based on a change in the current value flowing between the electrodes provided inside and outside the aperture tube, and the counted value counted for 30 seconds is 1000 or less A method for producing a body.

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