JP3916021B2 - Manufacturing method of ceramic filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a ceramic filter, and more specifically, a porous sintered ceramic filtration membrane layer having a fine pore diameter is formed on the inner surface of a tubular porous ceramic substrate such as a tube or a cylinder, and an open end surface thereof. Manufacturing method of a ceramic filter sealed with the sintered ceramic film layer, particularly a ceramic filter that significantly reduces the manufacturing cost compared with the conventional method by simultaneously performing the formation of the filtration film layer and the sealing of the end face It relates to the manufacturing method.
[0002]
[Prior art]
Ceramic filters are widely used for air purification, gas purification, etc. in other fields as well as for dust removal in the precision industry such as the semiconductor manufacturing industry. .
Conventionally, a ceramic filter is generally formed by sintering a ceramic sintered membrane layer (filtration membrane layer) having a pore size smaller than the pore size of the porous substrate on one side of the surface of the substrate made of permeable porous ceramics. Made.
[0003]
For example, in the case of a tubular ceramic filter with both ends open, the film layer is usually formed after sintering the film layer on one side of the inner and outer surfaces of a long circular tube base. The substrate tube was cut into a predetermined length, and both end faces were sealed to obtain a product.
That is, in the state where the long circular tube with the filtration membrane layer formed is cut, the cut surface (end surface) is in a state where the ceramic porous material of the substrate is exposed on the surface, and this portion is used when the ceramic filter is used. This causes the inconvenience that leaks occur and complete filtration and separation cannot be performed.
Further, due to stress strain caused by mechanical force applied at the time of cutting, the film layer at the end of the substrate often peels off or is damaged. In this case as well, as described above, there was a problem in that when this ceramic filter was used, a leak occurred from this portion and complete filtration and separation could not be performed.
[0004]
In order to avoid this inconvenience, the tubular ceramics filter needs to seal both end faces. The inconvenience described above also occurs at the open end of the cylinder type filter. Therefore, in a tubular ceramic filter such as a tube or cylinder, generally, a sealing process of the open end cross section is performed.
Such an open end sealing process is generally performed by selecting an appropriate inorganic material such as glaze or alumina-based ceramic bond as a sealing adhesive material, preparing a slurry thereof, and opening the filter. The part is immersed in this slurry, and the attached material is sintered to form a sealing layer.
[0005]
For example, in Japanese Patent Laid-Open No. 1-284316, ceramic fine particle slurry is adhered to both end surfaces after cutting of a cylindrical multilayer ceramic filter in which filtration layers are laminated by a method such as dipping or brushing. A method of manufacturing a ceramic filter by firing and forming a sealing layer made of a ceramic fine particle sintered layer on the end face is disclosed. Japanese Patent Application Laid-Open No. 62-132518 has a filter membrane layer formed on the inner surface side. An invention of an end-sealed porous filter in which an end surface of a porous ceramic filter is sealed with a sealing agent such as glaze is disclosed.
Japanese Patent Laid-Open No. 3-270704 discloses that the end of a ceramics tubular filter composed of a coarse particle layer and a fine particle layer is immersed in a sealing slurry liquid (glaze), and the filter inner hole is vacuum-sucked. Thus, an end sealing method for a ceramic tubular filter is disclosed in which a sealing film is formed on the outer peripheral surface of the filter end.
[0006]
[Problems to be solved by the invention]
However, in the conventional ceramic filter manufacturing methods described above, fine particles for forming a filtration membrane layer are deposited in layers on the inner or outer surface of a porous ceramic substrate formed in a predetermined shape, and then this is fired once. Then, a fine porous sintered filtration membrane layer is formed on the adhering surface, cut and processed, and then a sealing material is adhered to the open end surface portion and further sintered. For this reason, two sintering steps are required until the ceramic filter product is completed.
Therefore, the labor, time, and cost required for the two firings are increased accordingly, and the reduction of the manufacturing cost has become a major technical problem in manufacturing the ceramic filter.
Therefore, the present invention performs the sintered filtration membrane layer formation and the end face sealing at the same time in the manufacturing process of the ceramic filter in which the cylindrical open end face such as a tube or cylinder is sealed. An object of the present invention is to provide a ceramic filter manufacturing method for completing a product filter.
[0007]
[Means for Solving the Problems]
According to the present invention, at least one end face of the cylindrical porous ceramic base is opened at its open end with a lid composed of a bottom plate and a side body, and a slurry of ceramic particles is supplied to the inside of the base. A ceramic filter in which ceramic particles are adhered in a layer form on the inner peripheral surface of the substrate, and fired after removing the lid to form a porous ceramic sintered film layer having a pore diameter smaller than the pore diameter of the substrate on the inner peripheral surface of the substrate In mounting the lid body, the lid body is mounted so that a gap is formed between the inner surface of the lid bottom plate portion and the end surface of the base body when the cover body is mounted, and the supply slurry is passed between the inner peripheral surface and the end surface of the base body. A ceramic film is characterized in that a porous ceramic sintered film layer is simultaneously formed on the inner peripheral surface and the end surface of the substrate during the sintering by contacting the ceramic particles with the ceramic particles. Method for producing chromatography is provided.
[0008]
The method for producing a ceramic filter of the present invention is a production process of a ceramic filter for sealing an end face, wherein the formation of a microporous porous filtration membrane layer and the open end face sealing are simultaneously performed, and the ceramic filter is sintered. It is a remarkable feature that it can be done at once.
In order to achieve this, in the present invention, a lid made of rubber or the like is attached to the open end of a tubular porous ceramic substrate such as a tube or a cylinder, and the lid is provided inside, for example, the lid. A slurry of mixed particles is supplied from a supply pipe to a sintered filter membrane layer such as alumina or silica by a roller pump, and the slurry is brought into contact with the inner peripheral surface of the ceramic substrate to adhere the ceramic particles in layers. Let
[0009]
In this case, in the method for manufacturing a ceramic filter of the present invention, as shown in FIG. 2, the inner surface of the lid bottom plate portion 2d and the substrate end surface 1a are positioned to be separated from each other to some extent, thereby forming a gap between both surfaces. It is important that the slurry formed and infiltrated into this portion comes into contact with the end face of the substrate, and as a result, the ceramic particles adhere to form an adhered particle layer.
After supplying a predetermined amount of slurry, the slurry is discharged, and after drying, the substrate on which the particle layer is formed on the inner peripheral surface and the open end surface is fired, and porous firing with a fine pore diameter is performed on the inner peripheral surface and the end surface. A conjunctiva is formed.
In this way, if the filtration membrane layer formation and the end sealing are performed at the same time, the sintering process may be completed once, thereby achieving a significant reduction in manufacturing cost. Moreover, since the filtration membrane layer and the end face sealing film layer are formed as a continuous film layer of the same quality, the end face sealing film layer also functions as a filtration membrane layer, and the filtration efficiency is improved. In addition, by manufacturing the lid in accordance with the dimensions of the substrate, it is possible to cope with small lots and many kinds of products.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, the manufacturing method of the ceramic filter concerning this invention is demonstrated in detail based on drawing.
FIG. 1 is an explanatory view of an embodiment of the ceramic particle slurry supply apparatus for forming a sintered film layer used in the present invention, and FIG. 2 is an enlarged view of the main part (filter base mounting part).
1 and 2, reference numeral 1 denotes a filter base (tubular ceramic porous base), and lids 2 are attached to both ends of the filter base 1. Reference numeral 3 denotes a slurry supply pipe for supplying a slurry to the filter base 1 to which the lid 2 is attached. The slurry is attached to the slurry 2 from a slurry storage tank 5 via a roller pump 4 for slurry supply. Supplied to the inside of the filter base 1. Reference numeral 6 denotes a water tank filled with water.
[0011]
As apparent from FIG. 1, in the method for manufacturing a ceramic filter according to the present invention, an end portion 1a of a filter base 1 made of porous ceramics, in the example shown in FIG. The lid body 2 is attached to both end portions 1a, and is installed in a water tank 6 filled with water.
Further, since a slurry supply port 2b connected to the slurry supply pipe 3 is provided on one side of the lid 2, the slurry of the filter layer and the ceramic particles for forming the sealing layer is transferred from the slurry storage tank 5 to the roller. The pump 4 is supplied to the inside of the filter substrate 1 via the supply pipe 3, and the slurry is brought into contact with the inner peripheral surface of the substrate to adhere particles.
When a predetermined amount of slurry is supplied and a particle layer having a thickness sufficient for forming a sintered film layer is adhered to the slurry contact surface, the slurry supplied to the inside of the substrate 1 is discharged, and after discharging, the substrate 1 is removed from the water tank. Take out.
After removing the lid 2 from the base, it is dried and then fired to sinter the adhering ceramic particle layer to form a sintered film layer of fine porous ceramic on its inner peripheral surface and open end surface.
[0012]
In the method for manufacturing a ceramic filter according to the present invention, as shown in FIG. 2, the lid 2 has an inner surface 2a of the lid bottom plate portion 2d and is separated from the filter base end surface 1a. The lid 2 is mounted so that a gap 7 is formed between the two.
That is, by mounting the lid body 2 in this way, the supply slurry is also supplied and filled into the gap 7, the slurry comes into contact with the filter substrate end surface 1 a, and the substrate end surface 1 a is also in the inner periphery of the substrate 1. The adhered particle layer is formed in the same manner as the surface 1b.
Therefore, by sintering the adhered particle film layer, the sintered film layer made of the fine porous ceramic is transformed into the inner peripheral surface (filtration membrane layer) 1b of the filter base 1 and the open end surface (sealing) in a single sintering process. Layer) 1a.
[0013]
The interval between the inner surface of the lid bottom plate and the substrate end surface set when the lid is mounted is such that the supply slurry can enter the gap 7 formed between both surfaces, and the ceramic particles can sufficiently adhere to the substrate end surface. Is set as appropriate according to the diameter, thickness, etc. of the filter substrate, but is usually 0.5 mm or more and about 1/4 to 4/4, preferably 1/4 with respect to the thickness of the filter substrate. The interval is set to 2 to 2/2.
[0014]
The filter base used in the method of the present invention is not particularly limited as long as it is a tubular porous ceramic having a gas permeability, such as a tubular or cylindrical shape, and is used as a normal material for a gas filter base. For example, a porous ceramic made of alumina, mullite, silica, silicon carbide, silicon nitride or the like is used.
Such a gas-permeable porous ceramic filter substrate is, for example, a tube or cylinder having a predetermined length, outer diameter and wall thickness of a powder having a particle size of about 10 to 30 μm, such as alumina, mullite, silica, silicon carbide, silicon nitride and the like. For example, this green molded body is produced by firing at a temperature of about 1700 to 1900 ° C. in a reducing atmosphere.
[0015]
In the case of a tubular filter with both ends open, a long tubular green molded body may be fired, and the resulting porous ceramic long tube may be cut into a predetermined length to form a substrate. In the case of a cylinder-type filter with one end closed, it is closed by joining a porous ceramic bottom plate of the same material to one end face of the cut ceramic tube, or a bottomed hollow with both ends closed It may be produced by cutting a ceramic long tube.
[0016]
As a molding method of these green molded bodies, for example, a molding method such as CIP molding or extrusion molding is used. In the case of CIP molding, it is usually preferable to blend a binder to the raw material particles at about several percent. In the case of molding, it is preferable to add about 1 to 2% of a lubricant, a plasticizer and the like.
[0017]
The ceramic filter substrate preferably has an average pore diameter of about 5 to 20 μm, and those having a pore diameter of less than 5 μm are inferior in air permeability as a filter. The ceramic particles in the slurry enter the pores and fill the pores, or it becomes difficult to form a uniform filtration membrane layer.
In the method of the present invention, it is preferable that the lid is attached to the open end of the ceramic filter base with the inner peripheral surface of the side body closely contacting the outer peripheral surface of the filter base without any gap. When a gap is formed in the mounting portion, slurry enters the portion, and an adherent particle film layer is also formed in the slurry intrusion portion on the outer peripheral surface of the substrate, a film formed on the outer peripheral surface of the substrate when the lid is detached. If the layer is partially peeled or damaged by friction with the inner peripheral surface of the lid or by being pulled to the inner peripheral surface of the lid, the end surface continuous with the film layer on the outer peripheral surface of the substrate The formed film layer may be partially peeled or damaged due to the influence.
[0018]
As the material used for the lid, stainless steel, other metals, polytetrafluoroethylene, other synthetic resins, rubber or composite materials combining these can be used. When used, it is preferable that at least the portion in contact with the slurry inside the lid is not made of stainless steel or other metals.
When the part in contact with the slurry is made of metal, the ceramic particles in the supply slurry collide with the metal surface, wear the metal, and the generated metal fine particles are mixed into the slurry, adversely affecting the semiconductor manufacturing environment when using the filter. This is because there is a possibility.
[0019]
As a preferred example of the lid used in the present invention, as shown in FIG. 3, the outer surface side of the lid body 2 is made of a metal layer such as stainless steel, and the inner surface 2a of the lid body side body portion 2c which is a contact portion with the base. The side can be a two-layer structure made of a synthetic resin such as polytetrafluoroethylene or a flexible material 9 such as rubber, and a lid provided with a screw 8 on the metal layer side trunk can be exemplified.
As shown in FIG. 3, for example, a rubber material 9 is attached to the inner surface of the lid-side body, and the inner surface of the lid-side body and the outer peripheral surface of the base are brought into close contact with each other by tightening screws 8 from the outer surface side of the lid. If the screw 8 is sometimes loosened to remove the lid 2, the object of the present invention can be suitably achieved without damaging the adhered particle film layer.
[0020]
In the present invention, the kind of ceramic particles used for the slurry for forming the sintered film layer is preferably the same type as the ceramic particles used for forming the ceramic filter substrate, but is not particularly limited. Further, those having a smaller particle size than the ceramic particles for forming the substrate are used.
In general, it is preferable to use an average particle size in the range of 0.1 to 2.0 μm. If the average particle size is less than 0.1 μm, the particle size is too small and the film becomes too dense, resulting in a large pressure loss. On the other hand, if it exceeds 2.0 μm, the particles are too large and the filtration performance such as the particle removal function becomes insufficient.
The slurry is preferably an aqueous slurry having a ceramic particle concentration of about 1 to 20% by weight, and more preferably, polyethylene glycol or the like is added to adjust the slurry viscosity to about 100 to 300 cps. If it is less than 100 cps, the ceramic particles in the slurry pass through the pores of the porous substrate and are discharged to the outer peripheral side of the substrate, or the ceramic particles enter the pores of the substrate and fill the pores. On the other hand, if it exceeds 300 cps, the particle adhesion layer is difficult to form and the solvent in the slurry is difficult to be removed.
[0021]
The method for supplying the slurry is not limited to that using the supply device shown in FIG. 1, and the slurry can be supplied to any inner side of the substrate as long as the slurry can be brought into contact with the filter substrate to adhere the ceramic particles. The slurry may be discharged by gravity at a stage where the particle layer having a sufficient thickness for forming a sintered film layer is attached for a certain period of time.
In addition, since the slurry is supplied by a pump in the supply device shown in FIG. 1, pressure is applied to the inside of the substrate. In addition to this, according to the method of applying pressure to the inside of the substrate, the slurry is formed on the inner periphery of the porous substrate. It is preferable because it can be pressed against a surface or an end surface to form an adhered particle film layer having a uniform thickness, and the solvent in the slurry is easily discharged to the outer peripheral side of the porous substrate.
When the slurry is supplied using a pump, the slurry supply rate to the inside of the filter substrate is preferably about 0.03 to 0.3 ml / second. If the supply rate is higher than this, the ceramic particles in the slurry are porous substrate. The ceramic particles pass through the pores and are discharged to the outer peripheral side of the substrate, or ceramic particles enter the pores of the substrate and fill the pores. On the other hand, if the speed is too slow, the thickness of the formed particle adhesion layer becomes non-uniform.
Further, as shown in FIG. 4, it is more preferable to chamfer the corner 1c on the inner peripheral surface side of the end portion of the filter base 1 or to form an alarm so that the slurry can easily flow into the base end face 1a.
[0022]
Moreover, it is preferable to supply the slurry after impregnating the filter base with water in advance, or to supply the slurry after the filter base is immersed in the water tank 6 as shown in FIG.
As described above, when air does not exist in the pores of the porous filter substrate 1 and water is impregnated, the air existing in the pores passes through the particle adhesion film layer during the sintering and escapes. As a result, generation of defects in the film can be prevented. Further, it is possible to prevent the ceramic particles in the slurry from passing through the pores of the substrate and being discharged to the outer peripheral side of the substrate, or entering the pores of the substrate and filling the pores.
[0023]
The filter substrate on which the ceramic particle adhesion film layer is formed is dried at 70 to 80 ° C. for 1 to 3 hours, and the sintering after drying varies depending on the type of the ceramic particles. The temperature is set to 1400 to 1600 ° C., 1250 to 1400 ° C. for silica particles, and 1200 to 1350 ° C. for zirconia.
When the temperature is lower than the lower limit of each of the above ranges, the sintering is insufficient and the bonding strength between the base and the sintered film layer is insufficient. On the other hand, when the upper limit temperature is exceeded, the pore size of the sintered film becomes too large due to grain growth. .
[0024]
The thickness of the sintered film layer on the end face of the substrate is preferably in the range of 20 to 30 μm. If the thickness of the sealing film layer is less than 20 μm, leakage is likely to occur. When the sheet is pressed with a built-in gasket (sealing member), the end film may be destroyed.
Moreover, the average pore diameter of the fine porous membrane layer (inner peripheral surface filtration membrane layer and end face sealing membrane layer) formed by sintering is 0.1 to 1.5 μm, more preferably 0.2 to 0.00. A range of 8 μm is preferable from the viewpoint of filtration performance of the product filter and gas permeation pressure loss (usually evaluated as a bubble point).
[0025]
The ceramic filter with the sealed end face manufactured by the above-described method for manufacturing a ceramic filter of the present invention is incorporated into a module, for example, for dust removal in gas in the precision industry field such as the semiconductor manufacturing industry field, etc. It can be suitably used for applications such as air purification and gas purification in the above fields.
[0026]
【Example】
A binder (polyvinyl alcohol 2% by weight) in a mixed alumina powder in which coarse alumina having an average particle size of 18 μm and a particle size range of 10 to several tens of μm and fine alumina having an average particle size of 0.2 μm are mixed at a mixing ratio of 9: 1. Was molded into a circular tube by CIP molding, and this was fired in a reducing atmosphere at 1800-1870 ° C. for 2 hours.
The obtained sintered circular tube was cut to produce a tubular porous ceramic filter substrate having an outer diameter of 19 mm, an inner diameter of 15 mm, a length of 40 cm, and an average pore diameter of 12 μm. Synthetic rubber lids were attached to both ends of the filter base material as shown in FIG. 2, and set in the water tank of the ceramic sintered film forming slurry supply apparatus shown in FIG.
[0027]
Separately, an aqueous slurry (viscosity: 300 cps) consisting of 10% by weight of alumina powder having an average particle size of 1.2 μm, 50% by weight of polyethylene glycol, 2% by weight of diethylene glycol and the balance being water is prepared. Was supplied at a transfer rate of 0.1 ml / sec, and an adhered alumina particle layer was formed on the inner peripheral surface and end surface of the substrate.
The substrate to which the alumina particle layer is adhered is dried at 80 ° C., and then fired at 1500 ° C. for 2 hours in an air atmosphere to form a porous sintered film having an average pore diameter of 0.8 μm on the inner peripheral surface and end surface of the substrate. Then, an end face-sealed ceramic filter (φ19 × φ15 × 400 mm), which is an embodiment of the present invention, was produced.
[0028]
As a result of mounting this filter on the module and evaluating its performance, the gas flow rate characteristics were 24 nl / min (original pressure 0.5 kgf / cm ³ ), bubble point (measured in ethanol) 4,000 mmH ₂ O or more. It was. This bubble point is the pressure when the gas is bubbled out of the filter when the filter is immersed in the liquid (here ethanol) and the gas is fed into the filter. Means.
In addition, the particle capturing ability is such that when particle air with a total particle size of 0.07 μm to 1.0 μm is passed through 20,000 to 60,000 particles / min, the number of particles in the gas after passing is zero. there were.
[0029]
【The invention's effect】
As described above, according to the method for manufacturing a ceramic filter according to the present invention, the end-face-sealed ceramic filter that conventionally required two sintering steps can be completed by one sintering, and the manufacturing process can be shortened. At the same time, the cost required for sintering can be saved accordingly, so that the manufacturing cost can be greatly reduced.
In addition, the filter manufactured by the method of the present invention, the filtration membrane layer and the end-face sealing membrane layer are formed as a homogeneous continuous membrane layer, so the end-face sealing membrane layer also functions as a filtration membrane layer, Filtration efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a schematic view for explaining one embodiment of a slurry supply apparatus for forming a sintered ceramic film layer used in the present invention.
FIG. 2 is an enlarged cross-sectional view of a portion where a lid is attached to the filter base in FIG.
FIG. 3 is a cross-sectional view showing a preferred example of the lid of the present invention.
FIG. 4 is a cross-sectional view showing a filter base according to the present invention.
[Explanation of symbols]
1 Filter base (tubular porous ceramic base)
1a Substrate end face (end)
1b Base inner peripheral surface 1c Chamfer (corner)
2 Lid 2a Lid inner surface 2b Slurry supply 2c Lid side trunk 2d Lid bottom plate 3 Slurry supply pipe 4 Roller pump 5 Slurry storage tank 6 Water tank 7 Air gap (gap)
8 Screw 9 Flexible material (rubber material)

Claims (11)

At least one end face of the cylindrical porous ceramic base body is opened at its open end with a lid made of a bottom plate portion and a side body, and a slurry of ceramic particles is supplied to the inside of the base body to provide an inner peripheral surface of the base body. In the method of manufacturing a ceramic filter, the ceramic particles are attached in a layer form, and fired after the lid is removed to form a porous ceramic sintered film layer having a pore size smaller than the pore size of the substrate on the inner peripheral surface of the substrate.
When attaching the lid, the lid is attached so that a gap is formed between the inner surface of the lid bottom plate and the end face of the base, and the supply slurry is brought into contact with the inner peripheral face and the end face of the base. A method for producing a ceramic filter, comprising attaching a ceramic particle to simultaneously form a porous ceramic sintered film layer on an inner peripheral surface and an end surface of a substrate during the sintering. 2. The method for manufacturing a ceramic filter according to claim 1, wherein when the lid is attached, an inner peripheral surface of a side body portion of the lid is brought into close contact with the outer peripheral surface of the base body. The method for manufacturing a ceramic filter according to claim 1 or 2, wherein the lid is made of rubber or synthetic resin. The lid body has a two-layer structure in which a side body outer surface side is formed of a metal layer provided with a screw, and a side body inner surface side in contact with the base is formed of a synthetic resin layer or a rubber layer. A method for producing a ceramic filter according to claim 2. 5. The interval between the inner surface of the lid bottom plate portion and the end surface of the substrate is set to an interval of 1/4 to 4/4 with respect to the thickness of the ceramic substrate. A method for producing a ceramic filter according to any one of the above. 6. The method for producing a ceramic filter according to claim 1, wherein the cylindrical porous ceramic base has an average pore diameter of 5 to 20 [mu] m. The method for producing a ceramic filter according to any one of claims 1 to 6, wherein the porous ceramic sintered film layer has an average pore diameter of 0.1 to 1.5 µm. The method for producing a ceramic filter according to any one of claims 1 to 7, wherein a thickness of the sintered film layer on the end face of the substrate is 20 to 30 µm. 9. The method for producing a ceramic filter according to claim 1, wherein the slurry is supplied after the porous ceramic substrate is impregnated with water in advance. The method for producing a ceramic filter according to any one of claims 1 to 9, wherein the slurry is supplied after the porous ceramic substrate is immersed and set in a water tank in advance. The method for manufacturing a ceramic filter according to any one of claims 1 to 10, wherein an end portion of the inner peripheral surface of the open end of the porous ceramic substrate is chamfered or formed into an alarm shape.

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