JP2009240871A - Ceramic filter and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic filter which is equipped with an NF membrane or a UF membrane and can reduce the number of calcination times to reduce manufacturing cost, and a method of manufacturing this ceramic filter. <P>SOLUTION: The ceramic filter comprises a substrate 111 obtained by sintering substrate particles Q<SB>ij</SB>having an average particle diameter of 2-60 μm, and a gap filling layer 141 embedded to a certain depth from the upper part of the substrate 111 and filling gaps between the substrate particles Q<SB>ij</SB>with gap filling particles Q<SB>rs</SB>having an average particle diameter 1/10-1/7 times that of the substrate particles Q<SB>ij</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ceramic filter having a nanofiltration membrane (NF membrane) or an ultrafiltration membrane (UF membrane), and a method for producing the ceramic filter.

  Conventionally, various methods for forming an ultrafiltration membrane (UF membrane) on a ceramic element made of a porous substrate are known. For example, in a ceramic element having a columnar shape and having a plurality of flow paths that axially penetrate between both end faces of the columnar shape, or a honeycomb-shaped integrated structure (monolith), each of the plurality of flow paths A method of forming a UF membrane on the inner surface by crossflow filtration is known (see Patent Documents 1 and 2).

  According to the definition of the International Union of Pure and Applied Chemistry (IUPAC), filtration membranes that block particles and polymers larger than 0.1 μm are “microfiltration membranes (MF membranes)”, particles in the range of 0.1 μm to 2 nm and high Filter membranes that block molecules are “ultrafiltration membranes (UF membranes)”, and filtration membranes that block particles and polymers that are smaller than 2 nm are “nanofiltration membranes (NF membranes)”. The development of filters is ongoing. However, if the ceramic filter has a pore size of 0.05 μm or less, molding with ceramic particles becomes difficult, and at present, a complicated structure and process are required to achieve a fine pore size of 0.05 μm or less. is there.

  In FIG. 9, a first UF film having a particle diameter of 1 μm is formed as an intermediate layer on the surface of a porous substrate to be an MF film having a particle diameter of 10 μm, and a second UF film having a particle diameter of 0.1 μm is formed on the intermediate layer. The state formed as a film layer is shown typically. In the case of the multilayer structure shown in FIG. 9, after forming the base material to be an MF film having a particle size of 10 μm, the base material is dried, and then the base material is fired, and further, as an intermediate layer with respect to the base material. The first UF film having a particle diameter of 1 μm is formed, the first UF film is dried, and then the first UF film is fired. Further, the second UF film having a particle diameter of 0.1 μm is formed as a film layer on the first UF film. Since the number of firings is increased, such as the second UF film is fired after the second UF film is dried, there is a problem that the manufacturing cost increases. If the particle diameter is uniform, the gap between the particles is theoretically 1/6 to 1/7 of the particle diameter, and therefore an NF film cannot be realized with a particle diameter of 0.1 μm.

As shown in FIG. 10, there is known a gradient method in which the particle diameter is successively reduced, but there is a problem that it is difficult to prepare particles by the gradient method.
JP-A-3-267129 JP-A 61-238315

  An object of this invention is to provide the ceramic filter provided with the NF film | membrane or UF film | membrane which can reduce the frequency | count of baking and can reduce manufacturing cost, and the manufacturing method of this ceramic filter.

  In order to achieve the above object, the first aspect of the present invention includes (a) a base material obtained by sintering base material particles having an average particle diameter of 2 to 60 μm, and (b) a constant depth from the upper part of the base material. It is a ceramic filter provided with a gap filling layer filled with gap filling particles having an average particle diameter of 1/10 to 1/7 of the average particle diameter of the base particles in the gap formed by the base particles. The gist.

  In the second aspect of the present invention, (i) the surface of the base material obtained by sintering the base particles having an average particle diameter of 2 to 60 μm by the cross-flow filtration method is 1/10 to the average particle diameter of the base particles. A film-forming coating liquid containing gap filling particles having an average particle diameter of 1/7 is adhered and penetrated into the inside of the substrate from the surface of the substrate, and the gap filling particles are filled into the gaps formed by the substrate particles. (B) a drying step for drying the film-forming coating solution that has penetrated into the base material after the adhesion / filling step; and (c) after the drying step, the gap filling particles and the base material particles are separated. And a firing process for forming a gap filling layer in which gap filling particles are filled in gaps formed by base material particles at a certain depth from above the base material. .

  ADVANTAGE OF THE INVENTION According to this invention, the frequency | count of baking can be reduced and the manufacturing cost can be provided, The ceramic filter provided with the NF film | membrane or UF film | membrane, and the manufacturing method of this ceramic filter can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The following embodiments of the present invention exemplify apparatuses and methods for embodying the technical idea of the present invention. The technical idea of the present invention is based on the material and shape of component parts. The structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

(Ceramic filter)
FIG. 2 illustrates an example of the ceramic filter 11f using the gap filling layer obtained by the method for manufacturing a ceramic filter according to the embodiment of the present invention.

  The ceramic filter 11f according to the embodiment of the present invention has a lotus-like monolithic structure (monolith) having a plurality of flow paths (cells) 113 that are defined by partition walls 114 and form axial fluid passages. . In the ceramic filter 11f according to the embodiment of the present invention, the flow path (cell) 113 has a circular cross section.

  FIG. 3 is a partially enlarged view of a cross-sectional view taken along the longitudinal direction of the ceramic filter 11f. Along the inner wall of a flow path (cell) 113 provided in a lotus shape on the base material 111 having a monolith structure, FIG. A gap filling layer 141 is embedded from the surface of 111 to a certain upper depth.

The flow path (cell) 113 may be formed to have a hexagonal cross section or a square cross section. According to the structure shown in FIG. 2, for example, when the mixture is introduced into the flow channel (cell) 113 from the end surface on the inlet side, one of the mixture is formed on the inner wall of the flow channel (cell) 113. Since it is separated in the gap filling layer 141 and passes through the porous partition wall 114 and is discharged from the outermost wall of the ceramic filter 11f, the mixture can be separated. That is, the gap filling layer 141 formed (embedded) from the surface of the base material 111 constituting the ceramic filter 11f to a certain depth above the base material 111 can be used as a separation membrane.

FIG. 1 is a schematic cross-sectional view showing a state in which gap filling particles Q _rs having an average particle diameter D ₂ are filled in gaps in a substrate 111 made of base particles Q _ij having an average particle diameter D ₁ . The average particle diameter of the base particle Q _ij can be arbitrarily selected within the range of 2 to 60 μm. The average particle diameter of the base particle Q _ij may be 60 μm or more, but the separation performance as a filter is lowered, which is not preferable in that the effect of the present invention is not significant. Although it is theoretically possible to set the average particle size of the base particle Q _ij to 2 μm or less, as will be described later, the average particle size of the gap filling particles Q _rs is set to 1 / of the average particle size of the base particle Q _ij. In consideration of selecting 10 to 1/7, in an industrial sense, difficulty increases at present. However, if such difficulty can be overcome, the average particle diameter of the base particles Q _ij may be 2 μm.

As mentioned at the beginning, if the particle diameter of the substrate particles Q _ij constituting the substrate 111 is uniform, the gap d between the substrate particles Q _ij is theoretically:
d = 1 / 6D ₁ to 1 / 7D ₁ (1)
Therefore, if D ₂ <d, the base material 111 can be filled with the gap filling particles Q _rs .

However, in reality, the base material particles Q _ij and the gap filling particles Q _rs constituting the base material 111 each have a particle size distribution as shown in FIG. As shown in FIG. 4, the particle size distribution of the fine particles can be approximated by a lognormal distribution in many cases. In FIG. 4, it is assumed that the mode diameter d _mod which is the maximum value of the frequency distribution is equal to the average particle diameter (median diameter) D _{50 at} which the cumulative frequency is 50%, but in reality, d _mod = D ₅₀ is not _satisfied. There are many cases. Even if the average particle diameter D ₅₀ is the same, the standard deviation σ ₂ of the particle size distribution shown in FIG. 4A is larger than the standard deviation σ ₁ of the particle size distribution shown in FIG. Therefore, in the particle size distribution shown in FIG. 4A, the particle size is distributed over a wide range of 0.1 μm to 0.7-1 μm, but in the particle size distribution shown in FIG. The particle size distribution is narrower than the particle size distribution shown in FIG. Considering the particle size distribution of the base particle Q _ij and the gap filling particle Q _rs , that is, the standard deviation, the gap filling particle Q having an average particle diameter of 1/10 to 1/7 of the average particle diameter of the base particle Q _ij It is preferable to use _rs .

Table 1 is an average pore diameter d _1, gap filling particles having an average particle diameter D ₁ and substrate particles Q _ij of substrate particles Q _ij constituting the substrate 111 of the ceramic filter according to an embodiment of the present invention provides the average particle diameter D ₂ and Q _rs, filter constituted by filling the gap filler particles Q _rs an average particle diameter D ₂ in a gap between the substrate 111 made of base material particles Q _ij an average particle diameter D ₁ (filtration membrane ) Average pore diameter d ₂ is shown for Example 1 and Example 2, respectively.

In Example 1, the average particle diameter D ₁ of the base particle Q _ij = 2.5 μm, the average pore diameter d ₁ = 0.8 μm, the average particle diameter D ₂ of the gap filling particles Q _rs = 0.29 μm, the filter ( It can be seen that the average pore diameter d ₂ of the filtration membrane) is 0.02 μm. On the other hand, in Example 2, the average particle diameter D ₁ of the base particle Q _ij = 47 μm, the average pore diameter d ₁ = 10 μm, the average particle diameter D ₂ of the gap filling particles Q _rs = 5.7 μm, and the filter (filtration membrane) ) Average pore diameter d ₂ = 0.15 μm. Here, the average particle diameters D ₁ and D ₂ are measured by a light scattering type particle size distribution measuring apparatus using laser diffraction, and an average particle diameter (median diameter) D ₅₀ that has a cumulative frequency of 50% is defined as an average particle diameter. In Table 1, the “average particle diameter” means the median diameter D ₅₀ measured with a light scattering type particle size distribution measuring device. A specific measuring device for the average particle diameters D ₁ and D ₂ is a LA-910 type laser diffraction / scattering type particle size distribution measuring device manufactured by HORIBA. On the other hand, the average pore diameters d ₁ and d ₂ were measured by a mercury intrusion method using an auto pore 9200 type mercury porosimeter manufactured by Shimadzu Corporation.

The solid line in FIG. 5 shows the particle size distribution of the gap-filling particles Q _rs used in Example 1. Although it can be seen that the logarithmic normal distribution has an average particle diameter D ₂ = 0.29 μm, the standard deviation σ ₁ is about 0.1 μm due to the particle size adjustment according to the embodiment of the present invention. It can be seen that the standard type standard deviation σ ₂ by the conventional particle size preparation method shown is smaller than about 0.25 μm, and the particle size distribution range is narrow. The standard deviation σ ₂ of the standard type according to the conventional particle size preparation method is about the same as the average particle size or 60 to 70%, but the standard deviation σ ₁ is the average particle size by the particle size preparation according to the embodiment of the present invention. It can be seen that it can be reduced to 40% or less, preferably about 35% or less. The lower limit of the standard deviation σ ₁ is actually about 5%, but may ideally be 5% or less.

The solid line in FIG. 6 shows the particle size distribution of the gap filling particles Q _rs used in Example 2. Although it can be seen that the logarithmic normal distribution has an average particle diameter D ₂ = 5.7 μm, the standard deviation σ ₁ = 1 μm is obtained by the particle size adjustment according to the embodiment of the present invention, which is indicated by a broken line. It can be seen that the standard type standard deviation σ ₂ by the conventional particle size preparation method is smaller than about 4 μm, and the particle size distribution range is narrow. The standard deviation σ ₂ of the standard type according to the conventional particle size preparation method is about the same as the average particle size or 60 to 70%, but the standard deviation σ ₁ is the average particle size by the particle size preparation according to the embodiment of the present invention. It can be seen that it can be reduced to about 20% or less.

The solid line in FIG. 7 shows the particle size distribution of the base material particles Q _ij constituting the base material 111 used in Example 1. Although it can be seen that the logarithmic normal distribution has an average particle diameter D ₁ = 2.5 μm, the standard deviation σ ₁ is about 0.5 μm by the particle size adjustment according to the embodiment of the present invention. Standard type standard deviation σ ₂ = 1 by the conventional particle size preparation method shown is smaller than about 5 μm and the particle size distribution range is narrow, thereby providing a uniform gap with an average pore diameter d ₁ = 0.8 μm. I understand that I can do it. The standard deviation σ ₂ of the standard type according to the conventional particle size preparation method is about the same as the average particle size or 60 to 70%, but the standard deviation σ ₁ is the average particle size by the particle size preparation according to the embodiment of the present invention. It can be seen that it can be reduced to about 30% or less. Although the particle size distribution of the base material particles Q _ij constituting the base material 111 used in Example 2 is not shown, similarly, by the particle size adjustment according to the embodiment of the present invention, according to the conventional particle size preparation method. The standard type particle size distribution range is narrow, thereby providing a uniform gap with an average pore diameter d ₁ = 10 μm.

  According to the ceramic filter according to the embodiment of the present invention, as shown in Table 1, an NF can be obtained with a simple structure without using a multilayer structure (see FIG. 9) or a gradient method (see FIG. 10). It can be seen that a membrane or a UF membrane can be realized. Since the structure is simple, the number of firings can be reduced and the manufacturing cost can be reduced. Moreover, since the same material can be used, self-sintering is possible, and the technical effect that corrosion resistance is improved is also obtained.

  The base material 111 serving as the main body of the ceramic filter 11f is formed as a lotus-shaped filter element made of a porous material by extrusion molding or the like. As the porous material, the corrosion resistance and the change in the pore diameter of the filtration portion due to the temperature change are included. For example, alumina can be used from the viewpoint of a small amount and sufficient strength, but ceramic materials such as cordierite, mullite, and silicon carbide can also be used in addition to alumina.

(Cross flow filtration device)
As shown in FIG. 8, the cross-flow filtration device used in the method for manufacturing a ceramic filter according to the embodiment of the present invention includes a film forming chamber 12 that houses a base material 111 and a bottom portion that is upstream of the film forming chamber 12. An upstream pipe 21a connected to the flange 123b, a circulating liquid pipe 21e connected to the upper flange 123a on the downstream side of the film forming chamber 12, and an air vent valve 18 connected to the circulating liquid pipe 21e in a T-branch manner. And the return pipe 21f, the first decompression pipe 21g branched from the bottom flange 123b of the film forming chamber 12, the vacuum trap 16 connected to the first decompression pipe 21g, and the second decompression pipe 21h connected to the vacuum trap 16. , A vacuum pump connected to the second decompression pipe 21h, and a drain pipe 21 connected to the upstream side pipe 21a by T-branching. And a supply pipe 21b, a drain valve 13 connected to the drain pipe 21d, a circulation pump 14 connected to the supply pipe 21b, a tank pipe 21c connected to the circulation pump 14, and a circulation connected to the tank pipe 21c. A tank 15. The film forming coating liquid is fed from the bottom flange 123b to the flange 123a by the circulation pump 14, and the film forming coating liquid returns to the circulation tank 15 through the circulation liquid pipe 21e and the return pipe 21f. While performing this circulation, vacuum suction is performed by the vacuum pump 17 through the first decompression pipe 21g, the vacuum trap 16, and the second decompression pipe 21h. When a predetermined amount of the film-forming coating solution obtained by filtering the substrate 111 is stored in the vacuum trap 16, the circulation pump 14 is stopped, the drain valve 13 is opened, and the film-forming coating liquid is passed through the upstream pipe 21a and the drain pipe 21d. Drain the liquid. Even if the suction by the vacuum pump 17 is stopped, it is filtered excessively with the residual pressure, so when a certain amount of the film-forming coating solution is stored in the vacuum trap 16, the primary side (circulation side) of the base 111 is obtained. The film-forming coating solution is discharged. After the film forming coating solution on the primary side of the substrate 111 is discharged, the drain valve 13 is closed, and the secondary side (filtration side) of the substrate 111 is held in vacuum.

  The film forming chamber 12 is a cylindrical storage case for storing the base material 111. A cylindrical upper element holding ring 122 a is provided above the film forming chamber 12, and a cylindrical lower element is provided below the film forming chamber 12. A retaining ring 122b is provided. The glaze seal 112a of the base material 111 is fixed in a vacuum sealed state by an upper element holding ring 122a by an O-ring 121a, and the glaze seal 112b of the base material 111 is vacuum-sealed by a lower element holding ring 122b by an O-ring 121b. It is fixed with. The circulating fluid pipe 21e is provided with a flow meter F1, and monitors and controls the linear speed (liquid feeding speed) when the film forming coating liquid is fed. Further, a pressure gauge P1 is connected to the upper part of the film forming chamber 122 to monitor and control the pressure when the film forming coating liquid is fed.

  The penetration depth from the surface of the base material 111 of the gap filling layer 141 shown in FIG. 3 can be adjusted by adjusting the vacuum pressure, the linear velocity and the time during the cross flow filtration.

(Outline of ceramic filter manufacturing method)
Below, the outline of the manufacturing method of the ceramic filter which concerns on embodiment of this invention is demonstrated. The method for manufacturing a ceramic filter described below is an example, and it is needless to say that the method can be realized by various other manufacturing methods including this modification example:
(A) First, a monolith substrate is formed by extrusion molding. For example, the particle size of a dry mixture obtained by mixing coarse-grained alumina and aluminum metal is adjusted with a trommel mixed pulverizer using alumina cobblestone. In addition, a lubricant such as stearic acid may be added to facilitate extrusion, and an organic binder may be added to impart strength to the extruded product and facilitate handling of the green body. Also good. For example, a batch of a mixture in which a liquid component prepared by adding a stearic acid / ethanol solution to a water / ethylene glycol / polyvinyl alcohol solution and stirring is added to a dry component is fed into an extruder, for example, length A monolithic base material 111 having a cylindrical shape of 1000 mm and a diameter of 30 mm and having 37 lotus-like holes penetrating the inside in the axial direction is extruded.

  (B) Next, the extruded base material 111 is gradually dried over at least 24 hours, and further periodically weighed to maintain the drying until the mass is kept constant.

  (C) Furthermore, the dried base material 111 is put into a firing furnace, heated to a firing temperature of 1425 to 1625 ° C. at 120 ° C./h to 200 ° C./h, and held at the firing temperature for 12 to 24 hours, The temperature is lowered at 120 ° C./h to 200 ° C./h.

  (D) On the other hand, after mixing coarse alumina, pure water and an organic binder at a predetermined ratio, the particle size is adjusted with a trommel mixing and grinding machine using alumina cobblestone. The film forming raw material after the particle size adjustment is diluted to a predetermined moisture concentration to prepare a film forming coating solution made of ceramic sol. The film-forming coating liquid contains gap-filled particles having an average particle diameter of 1/10 to 1/7 of the average particle diameter of the base particles after particle size adjustment.

(E) Then, in order to deposit the film-forming coating liquid on the base material 111 exposed on the surface of the inner wall of the flow path (cell) 113 of the base material 111 by the cross-flow filtration method, the base material 111 is shown in FIG. It is installed vertically in the film forming chamber 12 of the crossflow filtration apparatus shown. In the cross flow filtration, the liquid is fed from the bottom up to the base material 111 installed in the film forming chamber 12 of the cross flow filtration apparatus. For example, in the case of the substrate 111 having a diameter of 3 × 37 holes, the liquid feeding speed is controlled by the flow meter F1 so as to circulate at 1 L / min (linear speed 0.06 m / s). While circulating the circulating liquid (film forming coating liquid), the vacuum is pumped by the vacuum pump 17 from the secondary side (filtration side) of the substrate 111 through the first pressure reducing pipe 21g, the vacuum trap 16 and the second pressure reducing pipe 21h. Suction. By vacuum suction, a film-forming coating liquid containing gap filling particles having an average particle diameter of 1/10 to 1/7 of the average particle diameter of the substrate particles adheres to the surface of the substrate 111. The base material 111 penetrates into the inside of the substrate 111, and the gap filling particles are filled in the gaps formed by the base material particles. The vacuum pressure is set to 0.08 MPa or more using the pressure gauge P1. For example, in the case of the substrate 111 having a length of 1 m (membrane area 0.35 m ² ), about 70 to 100 mL of filtrate (film-forming coating solution) is placed in the vacuum trap 16. ) Is stored, the vacuum pump 17 is stopped (actually, a stop valve (not shown) provided in the second decompression pipe 21h may be closed while the vacuum pump 17 is operated), and the base 111 is removed. The circulating fluid (film formation coating solution) is discharged through the upstream piping 21a and the drain piping 21d by opening the drain valve 13. Even if the suction by the vacuum pump 17 is stopped, it is filtered excessively by the residual pressure. Therefore, when about 30 to 50 mL of filtrate (film formation coating solution) is accumulated, the primary side (circulation side) of the substrate 111 ) Is discharged by opening the drain valve 13. After the primary side (circulation side) circulating liquid (film forming coating liquid) of the substrate 111 was discharged, the drain valve 13 was closed and the vacuum pump 17 was operated again (actually, the vacuum pump 17 was operated). The stop valve (not shown) provided in the second pressure-reducing pipe 21h may be opened, and the secondary side (filtration side) of the base material 111 is vacuum-held for about 10 minutes. After the vacuum holding of the base material 111 is completed, the base material 111 is taken out from the cross flow filtration device.

  (F) After removing the base material 111 from the cross flow filtration device and wiping off the remaining liquid of the base material 111, the base material 111 is housed in a dryer (constant temperature bath) and dried using a dryer (constant temperature bath). The treatment is carried out to dry the film forming coating solution that has penetrated into the inside of the substrate. The drying treatment is performed for 20 to 30 hours by controlling the inside of the dryer at 25 to 60 ° C. and a humidity of 45 to 55%, preferably a humidity of 48 to 52%.

  (G) After completion of the drying treatment, the temperature of the base material 111 is increased to a firing temperature of 1850 to 1950 ° C. at a rate of 100 to 300 ° C./h, and the holding time of the base material 111 is 45 minutes to 3 hours at the firing temperature. Preferably, the gap filling particles and the base material particles are fired by holding for about 1 to 2.5 hours, and then the base material 111 is cooled to room temperature at 100 to 300 ° C./h to obtain the base material 111. That is, as shown in FIG. 3, the gap filling layer 141 is formed (embedded) in the vicinity of the surface of a certain depth (predetermined penetration depth) from the top of the base material 111.

  In addition, the vacuum pressure and linear velocity at the time of the cross flow filtration described above are examples, and the penetration of the gap filling layer 141 from the surface of the base material 111 by adjusting the vacuum pressure, the linear velocity and the time at the time of cross flow filtration. The depth can be adjusted.

(Other embodiments)
As described above, the present invention has been described according to the above-described embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

The ceramic filter which concerns on embodiment of this invention WHEREIN: The typical expansion explaining the micro structure where the gap | interval of the base material was filled with the space | gap filling particle | grains with an average particle diameter smaller than the base material particle | grains which comprise a base material. It is sectional drawing. It is a bird's-eye view explaining the schematic structure of the ceramic filter which concerns on embodiment of this invention. FIG. 4 is a partially enlarged view of a cross section along the longitudinal direction of the ceramic filter according to the embodiment of the present invention, and a gap filling layer on an upper wall of a flow path (cell) provided in a lotus shape on a base material of a monolith structure The structure with embedded is schematically shown. In many cases, the particle size distribution of the fine particles can be approximated by a logarithmic normal distribution. Even if the average particle size is the same, the standard deviation of the particle size distribution shown in FIG. It shows that it is larger than the standard deviation of the particle size distribution shown in b). The standard deviation of the particle size distribution of the gap-filled particles used in Example 1 indicated by the solid line is smaller than the standard deviation of the standard type by the conventional particle size preparation method indicated by the broken line, which is approximately equal to the average particle size, and the particle size distribution It is a figure explaining that the range is narrow. The standard deviation of the particle size distribution of the gap-filled particles used in Example 2 shown by the solid line is smaller than the standard deviation of the standard type by the conventional particle size preparation method shown by the broken line, the average particle size being almost equal, and the particle size distribution It is a figure explaining that the range is narrow. The standard deviation of the particle size distribution of the base material particles constituting the base material used in Example 1 indicated by the solid line is equal to the standard deviation of the standard type by the conventional particle size preparation method indicated by the broken line, with the same average particle diameter. It is a figure explaining that it is small and the particle size distribution range is narrow. It is a schematic diagram explaining the outline of the crossflow filtration apparatus used for the manufacturing method of the ceramic filter which concerns on embodiment of this invention. As an explanation of the prior art, a first UF film having a particle diameter of 1 μm is formed as an intermediate layer on the surface of a porous substrate that becomes an MF film having a particle diameter of 10 μm, and a second UF having a particle diameter of 0.1 μm is formed on the intermediate layer. It is a figure which shows typically the state which formed the film | membrane as a film layer. It is a schematic diagram explaining the inclination method which makes a particle diameter small sequentially as description of a prior art.

Explanation of symbols

11f ... Ceramic filter 12 ... Deposition chamber 13 ... Drain valve 14 ... Circulation pump 15 ... Circulation tank 16 ... Vacuum trap 17 ... Vacuum pump 18 ... Air vent valve 21a ... Upstream piping 21b ... Supply piping 21c ... Tank piping 21d ... Drain Piping 21e ... Circulating fluid piping 21f ... Return piping 21g ... 1st decompression piping 21h ... 2nd decompression piping 111 ... Base material 112a, 112b ... Glaze seal 114 ... Partition 121a, 121b ... O-ring 122 ... Deposition chamber 122a ... Upper part Element retaining ring 122b ... Lower element retaining ring 123a ... Flange 123a ... Upper flange 123b ... Bottom flange 141 ... Gap filling layer F1 ... Flow meter P1 ... Pressure gauge

Claims (8)

A base material obtained by sintering base material particles having an average particle diameter of 2 to 60 μm;
A gap filling particle having an average particle diameter of 1/10 to 1/7 of the average particle diameter of the base material particles was filled in the gap formed by the base material particles at a certain depth from the top of the base material. A ceramic filter comprising a gap filling layer.   2. The ceramic filter according to claim 1, wherein a standard deviation of the base particles in a log normal distribution is 5 to 40% of an average particle diameter of the base particles.   3. The ceramic filter according to claim 1, wherein a standard deviation of the gap filling particles in a lognormal distribution is 5 to 40% of an average particle diameter of the gap filling particles.   The base material has a columnar shape and includes a plurality of flow paths that penetrate between both end faces of the columnar shape in the axial direction, and the gap filling layer is provided along each inner wall of the plurality of flow paths. The ceramic filter according to any one of claims 1 to 3, wherein the ceramic filter is provided. Filling the surface of a base material obtained by sintering base particles having an average particle diameter of 2 to 60 μm by a cross-flow filtration method with an average particle diameter of 1/10 to 1/7 of the average particle diameter of the base particles An adhesion / filling step of adhering a film-forming coating liquid containing particles, penetrating from the surface of the base material into the base material, and filling the gap filling particles into gaps formed by the base material particles;
After the adhesion / filling step, a drying step of drying the film-forming coating solution that has penetrated into the base material;
After the drying step, the gap filling particles and the base material particles are fired to form a gap filling layer in which the gap filling particles are filled in a gap formed by the base material particles at a certain depth from the upper part of the base material. A method for producing a ceramic filter, comprising: a firing step to be formed.   6. The method for producing a ceramic filter according to claim 5, wherein a standard deviation of the base particles in a log normal distribution is 5 to 40% of an average particle diameter of the base particles.   The film-forming coating solution is prepared by adjusting the particle size of the gap filling particles so that the standard deviation of the gap filling particles in the logarithmic normal distribution is 5 to 40% of the average particle diameter of the gap filling particles. The method for producing a ceramic filter according to claim 5 or 6, wherein:   The base material has a columnar shape, and includes a plurality of flow paths that penetrate axially between both end faces of the columnar shape, and the film-forming coating liquid is formed on the base material from the inner walls of the plurality of flow paths. The method for manufacturing a ceramic filter according to any one of claims 5 to 7, wherein the gap filling layer penetrates inside and is formed along inner walls of the plurality of flow paths.