Manufacturing method of water purification membrane structure

Abstract

To provide a production method of a film structure for water purification having an increased filtration cell area per unit floor area.SOLUTION: A production method of a film structure for water purification 1 comprises a step of forming a porous material and a step of forming a seal. In the step of forming the porous material, a plurality of filtration cells 11 to which raw water is supplied and a porous material 10 having a water collection hole 15 through which purified water is collected are formed. In the step of forming the seal, a seal 20 made of impermeable material which covers approximately the whole surface of the porous material 10 excluding each of the filtration cells 11 and the water collection hole 15 is formed.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for producing a water purification membrane structure. [Background technology]

[0002] Patent Document 1 discloses a ceramic pervaporation membrane that includes a columnar porous body and a filtration membrane as a water purification membrane structure for producing purified water from raw water.

[0003] The cylindrical porous body has a number of filtration cells that are open on both end faces and to which raw water is supplied, a number of water collection cells that are not open on both end faces and to which purified water is collected, and slits that penetrate each of the water collection cells and open to the side. A filtration membrane is formed on the inner surface of each filtration cell. The purified water that permeates the filtration membrane is discharged to the outside from the side face and the slits of the porous body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2010 / 134514 Summary of the Invention [Problem to be solved by the invention]

[0005] In the ceramic pervaporation membrane described in Patent Document 1, purified water is released from the sides and slits of the porous body, so the entire ceramic pervaporation membrane needs to be sealed in a watertight casing.

[0006] Therefore, when a casing with a sealed ceramic pervaporation membrane is actually installed, the filtration cell area per unit floor area becomes small due to the large size of the casing.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a manufacturing method for a water purification membrane structure that can increase the filtration cell area per unit floor area. [Means for solving the problem]

[0008] The method for manufacturing a water purification membrane structure according to the present invention is a method for manufacturing a water purification membrane structure for producing purified water from raw water, and includes a porous body forming step and a seal forming step. In the porous body forming step, a porous body is formed that is a columnar body having a first end face, a second end face opposite to the first end face, and a side face connected to the first end face and the second end face, and has therein a plurality of filtration cells to which raw water is supplied and a water collection hole through which purified water is collected. In the seal forming step, a seal is formed that has a first end face seal covering the first end face, a second end face seal covering the second end face, and a side face seal covering the side face, and is made of a water-impermeable material. The plurality of filtration cells penetrate the porous body from the first end face to the second end face, and open to the first end face seal and the second end face seal, respectively. The water collection hole penetrates the porous body from the first end face to the second end face, and opens to the first end face seal. Effect of the Invention

[0009] According to the present invention, a method for producing a water purification membrane structure capable of increasing the filtration cell area per unit floor area can be provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a water purification membrane structure. [Diagram 2] FIG. 2 is a perspective view of the water purification membrane structure. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line BB of FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line CC of FIG. [Figure 6] FIG. 6 is a vertical cross-sectional view of the water purification membrane structure. [Figure 7] FIG. 7 is a cross-sectional view of the water purification membrane structure. [Figure 8] FIG. 8 is an enlarged view of the area AR in FIG. [Figure 9]FIG. 9 is a schematic diagram for explaining a method for producing a water purification membrane structure. [Figure 10] FIG. 10 is a cross-sectional view of an extruder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Configuration of water purification membrane structure 1) The configuration of the water purification membrane structure 1 will be described with reference to the drawings.

[0012] Fig. 1 and Fig. 2 are perspective views of the water purification membrane structure 1. Fig. 3 is a cross-sectional view taken along line AA in Fig. 1. Fig. 4 is a cross-sectional view taken along line BB in Fig. 1. Fig. 5 is a cross-sectional view taken along line CC in Fig. 1. Fig. 6 is a cross-sectional view of the water purification membrane structure 1 partially cut vertically. Fig. 7 is a cross-sectional view of the water purification membrane structure 1 partially cut horizontally.

[0013] The water purification membrane structure 1 is used to produce purified water from raw water. The water purification membrane structure 1 is used while immersed in a storage tank in which raw water is stored.

[0014] The water purification membrane structure 1 has a monolith structure. The monolith structure refers to a structure having a plurality of cells penetrating in the longitudinal direction, and is a concept that includes a honeycomb structure.

[0015] The water purification membrane structure 1 includes a columnar porous body 10 and a seal 20 .

[0016] 1.Porous body 10 The porous body 10 according to this embodiment is a cylinder extending in the longitudinal direction. The external shape of the porous body 10 is not particularly limited, and may be, for example, an elliptical cylinder, a polygonal cylinder, a rectangular parallelepiped, or a square. The size of the porous body 10 is not particularly limited, and may be, for example, a length of 100 to 1500 mm and a diameter of 10 to 200 mm.

[0017] As shown in Figures 1 and 2, the porous body 10 has a first end face S1, a second end face S2, and a side face S3. The second end face S2 is provided on the opposite side of the first end face S1. The side face S3 is connected to the first end face S1 and the second end face S2. The outer edge of one end of the side face S3 is connected to the outer edge of the first end face S1. The outer edge of the other end of the side face S3 is connected to the outer edge of the second end face S2.

[0018] As shown in FIGS. 1 to 6, the porous body 10 has a plurality of filtration cells 11, a plurality of water collecting cells 12, a plurality of first water collecting slits 13, a plurality of second water collecting slits 14, and water collecting holes 15 therein.

[0019] As shown in Fig. 6, each filtration cell 11 penetrates the porous body 10 from the first end face S1 to the second end face S2. Each filtration cell 11 extends in the longitudinal direction of the porous body 10. Both ends of each filtration cell 11 open to a first seal 21 and a second seal 22, which will be described later, of the seal 20. Thus, each filtration cell 11 opens to both end faces of the water purification membrane structure 1. Raw water is supplied to each filtration cell 11 from the opening on the first seal 21 side and the opening on the second seal 22 side.

[0020] As shown in Fig. 3 to Fig. 5, the cross section of each filtration cell 11 according to this embodiment is circular. The cross-sectional shape of each filtration cell 11 is not particularly limited, and may be, for example, an ellipse or a polygon. The inner diameter (circumscribed circle diameter) of each filtration cell 11 is not particularly limited, and may be, for example, 1.0 mm or more and 3.0 mm or less. The number and positions of the filtration cells 11 can be set appropriately.

[0021] As shown in Figures 5 and 6, each water collecting cell 12 is provided inside the porous body 10. Each water collecting cell 12 extends in the longitudinal direction of the porous body 10. As shown in Figure 6, both ends of each water collecting cell 12 communicate with first and second water collecting slits 13, 14 inside the porous body 10. Purified water that has permeated the porous body 10 is collected in each water collecting cell 12.

[0022] As shown in Fig. 5, the cross section of each water-collecting cell 12 according to this embodiment is circular. The cross-sectional shape of each water-collecting cell 12 is not particularly limited, and may be, for example, elliptical or polygonal. The inner diameter (circumscribed circle diameter) of each water-collecting cell 12 is not particularly limited, and may be, for example, 0.5 mm or more and 3.0 mm or less. The number and positions of the water-collecting cells 12 can be set appropriately.

[0023] The first water collecting slits 13 collect purified water from the water collecting cells 12. A plurality of first water collecting slits 13 are provided to collect purified water evenly from the water collecting cells 12. As shown in Figs. 3 and 6, each first water collecting slit 13 is provided inside the end of the porous body 10 on the first end face S1 side. Each first water collecting slit 13 extends in a short direction perpendicular to the longitudinal direction of the porous body 10. The outer edge of each first water collecting slit 13 is sealed by a first plugging portion 13a. The outer surface of the first plugging portion 13a is covered by a first seal 21 of the seal 20, which will be described later. Each first water collecting slit 13 penetrates one or more water collecting cells 12.

[0024] As shown in Fig. 3, the multiple first water collection slits 13 include ten first communication slits 131 and six first non-communication slits 132. As shown in Figs. 6 and 7, each first communication slit 131 directly communicates with the water collection hole 15. Each first communication slit 131 opens into the water collection hole 15. Each first non-communication slit 132 does not directly communicate with the water collection hole 15. Each first non-communication slit 132 directly communicates with one or more first communication slits 131. Each first non-communication slit 132 indirectly communicates with the water collection hole 15 via one or more first communication slits 131.

[0025] The length of each first water collecting slit 13 in the longitudinal direction is not particularly limited, but may be, for example, 1% to 20% of the total length of the porous body 10. The number and positions of the first water collecting slits 13 can be appropriately set according to the number and positions of the water collecting cells 12.

[0026] The second water collecting slits 14 collect purified water from the water collecting cells 12. A plurality of second water collecting slits 14 are provided to collect purified water evenly from the water collecting cells 12. As shown in FIG. 4 and FIG. 6, each second water collecting slit 14 is provided inside the end of the porous body 10 on the second end face S2 side. Each second water collecting slit 14 extends in the short direction of the porous body 10. The outer edge of each second water collecting slit 14 is sealed by a second plugging portion 14a. The outer surface of the second plugging portion 14a is covered by a second seal 22 of the seal 20, which will be described later. Each second water collecting slit 14 penetrates one or more water collecting cells 12. Each second water collecting slit 14 collects purified water from each water collecting cell 12.

[0027] As shown in FIG. 4, the plurality of second water collection slits 14 include ten second communication slits 141 and six second non-communication slits 142. As shown in FIG. 6, each second communication slit 141 directly communicates with a water collection hole 15. Each second communication slit 141 opens into the water collection hole 15. Each second non-communication slit 142 does not directly communicate with the water collection hole 15. Each second non-communication slit 142 directly communicates with one or more second communication slits 141. Each second non-communication slit 142 indirectly communicates with the water collection hole 15 via one or more second communication slits 141.

[0028] The length of each second water collecting slit 14 in the longitudinal direction is not particularly limited, but may be, for example, 1% to 20% of the total length of the porous body 10. The number and positions of the second water collecting slits 14 can be appropriately set according to the number and positions of the water collecting cells 12.

[0029] As shown in FIG. 6, the water collection hole 15 is a bottomed recess that opens into the first end seal 21. The water collection hole 15 extends in the longitudinal direction inside the porous body 10. The second end face S2 side of the water collection hole 15 is sealed by a packing 15a. Therefore, in this embodiment, the bottom of the water collection hole 15 is formed by the packing 15a. In this manner, the water collection hole 15 opens only on one end face side of the water purification membrane structure 1. An O-ring (not shown) for connecting a purified water discharge pipe (not shown) is attached to the opening of the water collection hole 15 formed in the first end seal 21. The outer edge of the opening of the water collection hole 15 is preferably chamfered. This makes it easier to attach the O-ring and prevents the outer edge of the opening from being chipped when the O-ring is attached.

[0030] When the first seal 21 of the seal 20 is viewed in plan, the water collection hole 15 is disposed in the center of the first end surface S1 of the porous body 10. The water collection hole 15 is formed along the axial center of the porous body 10. A plurality of filtration cells 11 are disposed around the water collection hole 15.

[0031] The cross section of the water collection hole 15 according to this embodiment is circular. The cross-sectional shape of the water collection hole 15 is not particularly limited, and may be, for example, elliptical or polygonal. The inner diameter (circumscribed circle diameter) of the water collection hole 15 is not particularly limited, and may be, for example, 15% to 45% of the outer diameter (circumscribed circle diameter) of the porous body 10.

[0032] 6, first communication slits 131 and second communication slits 141 are opened on the inner peripheral surface of the water collection hole 15. The water collection hole 15 collects purified water from each of the first communication slits 131 and each of the second communication slits 141. The purified water collected in the water collection hole 15 is discharged to the outside through a purified water discharge pipe (not shown).

[0033] Here, Fig. 8 is an enlarged view of an area AR in Fig. 7. As shown in Fig. 8, the porous body 10 has a substrate 31 and a filtration layer 32.

[0034] The substrate 31 is the main body of the porous body 10. In the substrate 31, the water collecting cells 12, the first water collecting slits 13, the second water collecting slits 14, and the water collecting holes 15 described above are formed.

[0035] The base material 31 is made of a porous material and contains an aggregate and a binder.

[0036] Examples of the aggregate that can be used include alumina, silicon carbide, titania, mullite, cerium oxide, and cordierite. The binder is an inorganic oxide material that melts at a lower temperature than the aggregate components and bonds the aggregates together. The content of the aggregate in the base material 31 is not particularly limited, but can be, for example, 80% by volume or more and 99% by volume or less, and preferably 85% by volume or more and 95% by volume or less.

[0037] The binder may be an alumina or silica-based inorganic oxide material containing an alkali metal or an alkaline earth metal. The alkali metal may be at least one of sodium (Na), potassium (K) and lithium (Li). The alkali metal may exist in the form of an oxide. The alkaline earth metal may be at least one of magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba). The alkaline earth metal may exist in the form of an oxide. The binder preferably contains both an alkali metal and an alkaline earth metal. The content of the binder in the base material 31 is not particularly limited, but may be, for example, 1% by volume or more and 20% by volume or less, and preferably 5% by volume or more and 15% by volume or less.

[0038] The porosity of the substrate 31 is not particularly limited, but may be, for example, 25% to 50%, and preferably 30% to 45%. The porosity of the substrate 31 can be measured by mercury intrusion porosimetry. The average pore size of the substrate 31 is not particularly limited, but may be, for example, 0.1 μm to 50 μm, and preferably 1 μm to 10 μm from the viewpoint of improving the film formability of the filtration layer 32.

[0039] The filtration layer 32 is formed in a cylindrical shape. The space inside the filtration layer 32 is the filtration cell 11 described above.

[0040] In this embodiment, the filtration layer 32 includes a first filtration layer 32a and a second filtration layer 32b.

[0041] The first filtration layer 32a is formed on the inner surface of the base material 31. The first filtration layer 32a can be made of the above-mentioned porous material that can be used for the base material 31. The average pore diameter of the first filtration layer 32a may be smaller than the average pore diameter of the base material 31, and can be, for example, 0.005 μm or more and 5 μm or less. The average pore diameter of the first filtration layer 32a can be measured by a perm porometer. The porosity of the first filtration layer 32a is not particularly limited, but can be, for example, 20% or more and 60% or less. The thickness of the first filtration layer 32a is not particularly limited, but can be, for example, 1 μm or more and 300 μm or less.

[0042] The second filtration layer 32b is formed on the inner surface of the first filtration layer 32a. The second filtration layer 32b can be made of the above-mentioned porous material that can be used for the base material 31. The average pore size of the second filtration layer 32b may be smaller than the average pore size of the first filtration layer 32a, and can be, for example, 0.001 μm or more and 2 μm or less. The average pore size of the second filtration layer 32b can be measured by a perm porometer. The porosity of the second filtration layer 32b is not particularly limited, but can be, for example, 20% or more and 60% or less. The thickness of the second filtration layer 32b is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0043] 2. Seal 20 The seal 20 covers almost the entire surface of the porous body 10 except for the openings of each filtration cell 11 and the water collection holes 15. The seal 20 is made of a water-impermeable material. Examples of the water-impermeable material that can be used include glass, resin, metal, and rubber. Considering compatibility with the thermal expansion coefficient of the porous body 10, glass is suitable as the water-impermeable material.

[0044] As shown in FIGS. 1 and 2, the seal 20 according to this embodiment includes a first end face seal 21, a second end face seal 22, and a side seal .

[0045] The first end face seal 21 covers the first end face S1 of the porous body 10. However, the first end face seal 21 does not block the filtration cells 11 and the water collection holes 15, and as described above, the filtration cells 11 and the water collection holes 15 open into the first end face seal 21.

[0046] The second end face seal 22 covers the second end face S2 of the porous body 10. However, the second end face seal 22 does not block the filtration cells 11 and the water collection holes 15, and as described above, the filtration cells 11 and the water collection holes 15 open to the second end face seal 22.

[0047] The side seal 23 covers the side surface S3 of the porous body 10. The side seal 23 has no opening formed therein.

[0048] By covering the entire surface of the porous body 10 in this manner with the seal 20, a configuration is realized in which raw water is supplied to the inside only from each filtration cell 11, and purified water is discharged only from the water collection hole 15.

[0049] (Method of manufacturing water purification membrane structure 1) Next, a method for manufacturing the water purification membrane structure 1 will be described with reference to the drawings.

[0050] FIG. 9 is a schematic diagram illustrating a method for producing the water purification membrane structure 1. As shown in FIG.

[0051] The method for manufacturing the water purification membrane structure 1 includes a porous body forming step of forming the porous body 10, and a seal forming step of forming the seal 20. Each step will be described in detail below.

[0052] 1. Porous body formation process (1) Extrusion molding process First, a porous material for the substrate 31 is prepared and placed in the extrusion molding machine 50 .

[0053] Next, the porous material is extruded by an extrusion molding machine 50 to extrude a columnar base molding body 31X. The base molding body 31X has a plurality of filtration cell through holes (not shown) for forming a plurality of filtration cells 11, a plurality of water collection cell through holes (not shown) for forming a plurality of water collection cells 12, and a water collection hole through hole 15X.

[0054] FIG. 10 is a cross-sectional view of an extrusion molding machine 50. The extrusion molding machine 50 has a case 51, a material accommodation space 52, a die 53, and a pressing plate 54. The material accommodation space 52 is provided inside the case 51. A porous material is accommodated in the material accommodation space 52. The die 53 is disposed inside the case 51. Inside the die 53, slits corresponding to the patterns of the through holes for the water collection cells and the through holes for the water collection holes 15X are formed. A recess 53a is formed on the front surface of the die 53. A fixing plate 53b is accommodated in the recess 53a. The fixing plate 53b is a member for fixing the die 53. The pressing plate 54 is an annular member in which an opening is formed for defining the cross-sectional shape and dimensions of the base material molded body 31X.

[0055] Here, the bottom surface 53R of the recess 53a formed in the nozzle 53 includes an abutment surface r1 and an annular surface r2. The abutment surface r1 is the area of ​​the bottom surface 53R with which the fixed plate 53b abuts. The annular surface r2 is an annular area that corresponds to the inner wall of the water collection hole 15. It is preferable that the annular surface r2 is generally flat. Although the reason is not clear, by making the annular surface r2 flat, it is possible to suppress the occurrence of cracks in the inner wall of the water collection hole 15 compared to when the annular surface r2 is an inclined surface.

[0056] (2) Drying process The base material molded body 31X is dried. The base material molded body 31X may be dried forcibly by blowing hot air onto the base material molded body 31X placed on a stand, or may be dried naturally on the stand.

[0057] After drying the base material molded body 31X, both ends of the base material molded body 31X may be appropriately cut to adjust the length of the base material molded body 31X.

[0058] (3) Primary slit forming process A plurality of primary slits 13X penetrating the respective water collecting cell through holes are formed in a first end face of the base material molding 31X. Then, a plurality of primary slits 14X (not shown) penetrating the respective water collecting cell through holes are formed in a second end face of the base material molding 31X.

[0059] Each primary slit 13X ultimately becomes a part of each first water collecting slit 13, and each primary slit 14X ultimately becomes a part of each second water collecting slit 14.

[0060] There are no particular limitations on the depth of each of the primary slits 13X, 14X, but if it is too deep, deformation is likely to occur at both ends of the base material molding 31X, and if it is too shallow, the benefit of forming the primary slits in advance is diminished, so it is preferable to adjust the depth within a range that achieves both of these.

[0061] (4) Temporary filling process Each primary slit 13X is temporarily filled by forcing a temporary filling material into each primary slit 13X from a first end face side of the base material molding 31X to a predetermined depth. Then, each primary slit 14X is temporarily filled to a predetermined depth by forcing a temporary filling material into each primary slit 14X from a second end face side of the base material molding 31X to a predetermined depth. The porous material for the base material 31 can be used as the temporary filling material.

[0062] When pushing in the temporary packing material, it is preferable to push in the temporary packing material with the stoppers 57 inserted in the primary slits 13X and 14X. This allows the temporary packing material to be filled to a predetermined depth with a desired density.

[0063] (5) Substrate baking process The substrate molded body 31X is fired under predetermined conditions (for example, at 800° C. to 1500° C., for 10 hours to 200 hours) to form the substrate 31.

[0064] (6) Filtration layer formation process A slurry for the first filtration layer 32a is prepared by mixing a porous material for the first filtration layer 32a with water. Then, the slurry for the first filtration layer is pumped into each filtration cell through hole of the base material 31 under a negative pressure environment to form a first filtration layer molded body on the inner surface of each filtration cell through hole. Then, the base material 31 on which the first filtration layer molded body has been formed is fired under predetermined conditions (e.g., 800°C to 1500°C, 10 hours to 200 hours) to form the first filtration layer 32a.

[0065] Next, a slurry for the second filtration layer 32b is prepared by mixing a porous material for the second filtration layer 32b with water. The slurry for the second filtration layer is then pumped to the inside of the first filtration layer 32a under a negative pressure environment to form a second filtration layer molded body on the surface of the first filtration layer 32a. The base material 31 on which the second filtration layer molded body has been formed is then fired under predetermined conditions (e.g., 800°C to 1500°C, 10 hours to 200 hours) to form the second filtration layer 32b.

[0066] (7) Secondary slit forming process A cutting tool is used to cut each primary slit 13X deeper from the first end face side of the base material 31, thereby forming a plurality of secondary slits 13Y. Then, a cutting tool is used to cut each primary slit 14X deeper from the second end face side of the base material 31, thereby forming a plurality of secondary slits 14Y (not shown). As a result, a plurality of water collecting cells 12 are formed inside the base material 31.

[0067] In this process, the temporary packing material filled in each of the primary slits 13X, 14X is removed. Since each of the primary slits 13X, 14X is formed in advance, each of the secondary slits 13Y, 14Y can be formed relatively easily, and the tool life can be extended.

[0068] (8) Filling process Each secondary slit 13Y is sealed by forcing the weatherstripping material into a portion of each secondary slit 13Y that opens to the outer surface of the base material 31. In this way, a plurality of first water collecting slits 13 are formed inside the base material 31.

[0069] Next, each secondary slit 14Y is sealed by pushing the weatherstripping material into a portion of each secondary slit 14Y that opens to the outer surface of the base material 31. In this way, a plurality of second water collecting slits 14 are formed inside the base material 31.

[0070] As the main weatherstripping material, the porous material for the base material 31 can be used.

[0071] Through the above steps, the porous body 10 is completed.

[0072] 2.Seal formation process (1) End seal formation process A water-impermeable material is applied or printed on the first end surface S1 of the porous body 10 to form a first end surface seal body 21X.

[0073] Next, a water-impermeable material is applied or printed on the second end surface S2 of the porous body 10 to form a second end surface seal body 22X.

[0074] (2) Side seal forming process A water-impermeable material is applied or printed on the side surface S3 of the porous body 10 to form a side seal molding 23X.

[0075] In this step, it is preferable to apply or print the non-permeable material in a state where the porous body 10 is suspended by inserting the support member 56 into the through hole 15X for the water collection hole of the porous body 10. This allows the side seal molding 23X to be formed uniformly overall.

[0076] (3) Seal baking process Thereafter, the porous body 10 on which the seal moldings 21X, 22X, and 23X are formed is fired under predetermined conditions (e.g., 800°C to 1500°C, 10 hours to 200 hours). Thereafter, the second end face S2 side of the through hole 15X for water collection hole is sealed with a packing 15a, thereby completing the water purification membrane structure 1.

[0077] (Features) (1) The manufacturing method of the water purification membrane structure 1 includes a porous body forming step and a seal forming step. In the porous body forming step, a porous body 10 is formed having a plurality of filtration cells 11 to which raw water is supplied and water collection holes 15 through which purified water is collected. In the seal forming step, substantially the entire surface of the porous body 10 except for the filtration cells 11 and the water collection holes 15 is covered to form a seal 20 made of a water-impermeable material.

[0078] In this way, since the entire surface of the porous body 10 is covered with the seal 20, it is possible to manufacture a water purification membrane structure 1 that supplies raw water to the inside only from each filtration cell 11 and discharges purified water only from the water collection hole 15. Since such a water purification membrane structure 1 does not need to be sealed separately in a watertight casing, for example, when the water purification membrane structure 1 is installed in a water storage tank, the filtration cell area per unit floor area can be increased compared to when a casing is required.

[0079] (2) In the extrusion molding step, an extrusion molding machine 50 having a die 51 with a flat annular surface r3 corresponding to the inner wall of the water collection hole 15 is used to extrude a base molded body 31X having a plurality of filtration cell through holes and the water collection hole 15. This makes it possible to prevent cracks from occurring on the inner peripheral surface of the water collection hole 15. Note that a commonly known method of improving the flow of the porous material by inclining the annular surface r3 is, however, it has been experimentally confirmed that this method is prone to cracks occurring on the inner peripheral surface of the water collection hole 15.

[0080] (3) In the temporary filling step, with the stopper 57 inserted in the primary slit 13X, the temporary filling material is pushed into the primary slit 13X from the first end face side of the base material molded body 31X. This allows the temporary filling material to be filled to a predetermined depth with a desired density.

[0081] (4) The drying step and the firing step are performed in a state where the support member 56 is inserted into the water collecting hole 15 and suspended. This makes it possible to prevent the base molded body 31X and the base material 31 from being deformed.

[0082] (5) The side seal forming step is performed in a state where the support member 56 is inserted into and suspended from the water collection hole 15. This makes it possible to form the side seal formed body 23X uniformly over its entirety.

[0083] (Modification of the embodiment) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0084] [Variation 1] In the above embodiment, the configuration of the water purification membrane structure 1 has been described with reference to Figs. 1 to 7, but the detailed configuration of the water purification membrane structure 1 can be changed as appropriate. The water purification membrane structure 1 only needs to include a porous body 10 having filtration cells 11 and water collection holes 15, and a seal 20 that covers the surface of the porous body 10. Therefore, the water purification membrane structure 1 does not need to include the water collection cells 12, the first water collection slits 13, and the second water collection slits 14. Furthermore, it is sufficient that one or more filtration cells 11 and one or more water collection holes 15 are provided.

[0085] [Variation 2] In the above embodiment, the second end surface S2 side of the water collection hole 15 is sealed by the packing 15a, but the method for sealing the second end surface S2 side of the water collection hole 15 is not particularly limited.

[0086] [Variation 3] In the above embodiment, the primary slits 13X, 14X are formed for all the water-collecting cell through-holes in the primary slit forming step, and the primary slits 13X, 14X are temporarily filled in the temporary filling step, but this is not limited to the above. If there is a concern that forming the primary slits 13X, 14X for all the water-collecting cell through-holes will reduce the strength of the base molded body 31X, the primary slits 13X, 14X may be formed for some of the water-collecting cell through-holes in the primary slit forming step. In this case, the remaining water-collecting cell through-holes remain open, so in the filtration layer forming step, it is necessary to block the openings of the water-collecting cell through-holes as needed using an organic material that evaporates by firing.

[0087] [Variation 4] In the above embodiment, the filtration layer 32 has the first filtration layer 32a and the second filtration layer 32b, but is not limited to this. The filtration layer 32 may have only one of the first filtration layer 32a and the second filtration layer 32b, or may further have one or more filtration layers in addition to the first filtration layer 32a and the second filtration layer 32b. [Explanation of symbols]

[0088] 1. Water purification membrane structure 10 Porous bodies S1 1st end surface S2 2nd end face S3 Side 11 Filtration Cell 12 Collection cell 13 First water collection slit 14 Second water collection slit 15 Water collection hole 20 Seal 21 First end seal 22 Second Face Seal 23 Side seal 31 Base material 32 Filtration layer 32a First filtration layer 32b Second filtration layer 50 Extrusion Machine 51 cases 53 Cap 53a Recess 53b Fixed plate 53R Bottom r1 Contact surface r2 toroidal surface 56 Support member

Claims

1. A method for producing a water purification membrane structure for producing purified water from raw water, comprising: a porous body forming step of forming a porous body which is a columnar body having a first end face, a second end face opposite to the first end face, and a side face communicating with the first end face and the second end face, the porous body having therein a plurality of filtration cells to which the raw water is supplied and a water collection hole through which the purified water is collected; a seal forming step of forming a seal including a first end seal covering the first end face, a second end seal covering the second end face, and a side seal covering the side face, the seal being made of a water-impermeable material; Equipped with The porous body has a substrate and a cylindrical filtration layer formed on an inner surface of the substrate and allowing the purified water to pass through; The space inside the filtration layer is the filtration cell, The porous body forming step includes: forming a columnar base molding having a plurality of filtration cell through holes and a water collection hole through hole for forming the plurality of filtration cells; forming the substrate by firing the substrate molded body; forming a filtration layer molded body on the inner surfaces of the plurality of filtration cell through holes by using a filtration layer slurry containing a porous material; A step of forming the filtration layer by firing the base material on which the filtration layer molded body is formed; Including, The plurality of filtration cells extend through the porous body from the first end surface to the second end surface and open to the first end surface seal and the second end surface seal, The water collection hole is a bottomed recess that opens to the first end face seal. A method for manufacturing a water purification membrane structure.

2. The porous body forming step includes an extrusion molding step of extruding the base material molded body using an extruder having a die. A method for producing the water purification membrane structure according to claim 1.

3. the nozzle has an annular surface corresponding to an inner wall of the water collecting hole, The annular surface is a planar surface. A method for producing the water purification membrane structure according to claim 2.

4. In the extrusion molding step, a plurality of through holes for water-collecting cells for forming a plurality of water-collecting cells provided inside the porous body are formed in the base molded body, the porous body forming step includes a primary slit forming step of forming a primary slit penetrating the plurality of water collection cell through holes in the end surface of the base material molded body, and a temporary filling step of temporarily filling the primary slit to a predetermined depth, The primary slit forming process and the temporary filling process are performed sequentially after the extrusion molding process. A method for producing the water purification membrane structure according to claim 2 or 3.

5. In the temporary filling step, a temporary filling material is pushed into the primary slit from the end face side of the base material molding while a stopper is inserted into the primary slit. A method for producing the water purification membrane structure according to claim 4.

6. The porous body forming step includes a drying step of drying the substrate molded body before firing the substrate molded body, In the drying step, a support member is inserted into the water collecting hole and the base molded body is dried in a suspended state. A method for producing the water purification membrane structure according to any one of claims 1 to 5.

7. In the step of firing the base material molded body, a support member is inserted into the water collection hole and the base material molded body is fired in a suspended state. A method for producing the water purification membrane structure according to any one of claims 1 to 6.

8. In the seal forming step, a support member is inserted into the water collection hole to form the seal while the base molding is suspended. A method for producing the water purification membrane structure according to any one of claims 1 to 7.

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