Membrane cartridge and method for manufacturing the membrane cartridge

Abstract

To provide a membrane cartridge in which a fine structure is not provided at a support plate and a filtration membrane is not be easily damaged, and to provide a manufacturing method of the membrane cartridge.SOLUTION: A membrane cartridge includes a filtration membrane 2 and a support plate 3. The support plate 3 is provided with: a reference surface; a first joint part 32 protruding from the reference surface; and a second joint part 33 recessed from the reference surface. The second joint part 33 is provided closer to the outer edge 35 side of the support plate 3 relative to the first joint part 32. At least a part of an outer edge portion 21 of the filtration membrane 2 is joined to the support plate 3 at the second joint part 33. The inner side relative to the outer edge portion 21 in the filtration membrane 2 is joined to the support plate 3 at the first joint part 32.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a membrane cartridge and a method for manufacturing the membrane cartridge.

Background Art

[0002] As a filtration device used in sewage treatment facilities and the like, a device having a membrane cartridge is widely used. As such a membrane cartridge, a structure in which a filtration membrane made of a non-woven fabric or the like is joined to a support plate made of a resin material or the like is typical.

[0003] Examples of methods for joining a filtration membrane to a support plate include a welding method and an ultrasonic method. For example, Japanese Patent Application Laid-Open No. 2006-231139 (Patent Document 1) discloses a technique in which a non-woven fabric is placed on a support plate, and a hot plate is pressed from above the non-woven fabric to weld the support plate and the non-woven fabric. Further, Japanese Patent Application Laid-Open No. 2001-212436 (Patent Document 2) discloses a technique in which a non-woven fabric is placed on a support plate, and an ultrasonic horn is pressed against the non-woven fabric from above to join the support plate and the non-woven fabric.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the welding technique disclosed in Patent Document 1, the portion where the hot plate of the support plate was pressed might sink, and a raised portion might be formed around the sunken portion. In this case, when used in the membrane cartridge, vibration of the filter membrane with the raised portion as a fulcrum might occur, and the filter membrane might be likely to break. Also, in order to avoid this phenomenon, as disclosed in Patent Document 2, if a fine structure such as a protrusion is provided in advance on the support plate, in a particularly complex structure, the resin material might not be evenly distributed during molding, resulting in molding defects and a decrease in the productivity of the support plate.

[0006] Therefore, there is a need to realize a membrane cartridge in which the support plate is not provided with a fine structure and the filter membrane is not easily broken, and a method for manufacturing the membrane cartridge.

Means for Solving the Problems

[0007] The membrane cartridge according to the present invention includes a filter membrane and a support plate. On the support plate, a reference surface, a first joint portion protruding from the reference surface, and a second joint portion recessed from the reference surface are provided. The second joint portion is provided on the outer edge side of the support plate rather than the first joint portion. At least a part of the outer edge of the filter membrane is joined to the support plate at the second joint portion, and the inside of the filter membrane rather than the outer edge is joined to the support plate at the first joint portion The area including the top characterized in that.

[0008] Also, the method for manufacturing a membrane cartridge according to the present invention is a method for manufacturing a membrane cartridge in which a filter membrane is joined to a support plate having a reference surface, a first joint portion protruding from the reference surface, and a second joint portion recessed from the reference surface, An arranging step of arranging the filter membrane on a pre-arranged joining pre-support plate having the reference plane and the first joining portion; and a pressing member is pressed from above the filter membrane arranged on the joining pre-support plate to form the second joining portion by retreating a part of the reference plane, and a joining step of completing the joining of the filter membrane and the support plate at the first joining portion and the second joining portion, wherein, in the pressing member, a first portion facing the first joining portion is provided to retreat from a second portion forming the second joining portion.

[0009] According to these configurations, in the first joining portion, vibration of the filter membrane with the raised portion around the depressed portion as a fulcrum does not occur, and a membrane cartridge in which the filter membrane is less likely to break can be realized.

[0010] Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiment examples described below.

[0011] As one aspect, in the membrane cartridge according to the present invention, it is preferable that the edge portion on the outer edge side of the support plate of the second joining portion is alternately provided with a convex portion convex toward the outer edge side of the support plate and a concave portion concave from the outer edge side.

[0012] According to this configuration, since the second joining portion has a certain width in the plane direction, a tolerance range occurs in the plane direction positional relationship between the filter membrane and the support plate to realize the positional relationship in which the outer edge portion of the filter membrane abuts on the second joining portion. Therefore, variations in the dimensions of the filter membrane and deviations in the plane direction positional relationship between the filter membrane and the support plate can be tolerated to a certain extent, and the labor required for adjusting the positional relationship between the filter membrane and the support plate can be reduced.

[0013] As one aspect, in the membrane cartridge according to the present invention, the outer The edge is It is preferable that the filter membrane is joined to the support plate in a region between the convex portion and the concave portion of the second joining portion.

[0014] According to this configuration, it is easy to fix the outer edge portion of the filter membrane to the support plate.

[0015] In one aspect, in the manufacturing method of the membrane cartridge according to the present invention, it is preferable that the retraction distance of the first part with respect to the second part is smaller than the height of the first joint with respect to the second joint.

[0016] According to this configuration, it is easy to achieve a proper joint at both the first joint and the second joint.

[0017] In one aspect, in the manufacturing method of the membrane cartridge according to the present invention, it is preferable that the pressing member is heated.

[0018] According to this configuration, the filter membrane and the support plate can be heat-welded to form a good water seal.

[0019] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments with reference to the drawings.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0021] Embodiments of a membrane cartridge and a method for manufacturing the membrane cartridge according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the membrane cartridge according to the present invention is applied to a membrane cartridge 1 to be mounted on an immersion type membrane filtration device used by being immersed in water to be treated will be described. In FIGS. 1 to 6, the dimensional ratios of the respective members may be changed for the purpose of explanation, and the dimensional ratios of the illustrated respective members do not necessarily reflect the embodiments. In particular, in order to make the structures of the protruding portion and the retracting portion easier to understand, there are cases where they are illustrated in a manner emphasized in the protruding direction and the retracting direction. When there are numerical examples regarding the dimensions of each part in the present embodiment, the dimensions should be understood according to the numerical examples.

[0022] 〔Configuration of membrane cartridge〕 The membrane cartridge 1 according to the present embodiment has a structure in which a filtration membrane 2 is joined to a support plate 3 (FIG. 1). The filtration membranes 2 are joined one by one to both surfaces of the support plate 3.

[0023] In the use state, the membrane cartridge 1 is immersed in the water to be treated. When the water to be treated passes through the filtration membrane 2, solids in the water to be treated remain on the primary side of the filtration membrane 2, and the filtrate from which the solids have been removed flows into the secondary side of the filtration membrane 2. A plurality of grooves (not shown) are provided in the central portion of the support plate 3 (the portion covered by the filtration membrane 2 in FIG. 1), and the grooves communicate with the nozzles 31. The filtrate that has flowed into the secondary side of the filtration membrane 2 flows out to the downstream process through the grooves and the nozzles 31.

[0024] As shown in FIG. 1, the membrane cartridge 1 has a plate-like shape in which the thickness D is smaller than the width W and the length L. In the present embodiment, the width W of the membrane cartridge 1 is 500 mm, the length L is 1560 mm, and the thickness D is 6 mm. In the following description, when referring to the "plane direction", it refers to the direction along the plane defined by the width W and the length L of the membrane cartridge 1 (the XY plane direction in FIG. 1), or the extending direction of the filtration membrane 2 corresponding thereto. Further, the "direction intersecting the plane direction" refers to the thickness D direction of the membrane cartridge 1 (the Z-axis direction in FIG. 1).

[0025] The filter membrane 2 is a sheet-like member provided with a plurality of fine pores. The material constituting the filter membrane 2 is not particularly limited, and for example, it may be polyethylene, polypropylene, polyethylene terephthalate, etc. When the filter membrane 2 is composed of a polymer material, a material subjected to chemical modification such as chlorination may be used. Further, the size of the pores provided in the filter membrane 2 can be appropriately selected according to the size of the solid matter to be removed using the membrane cartridge 1, and the average pore diameter of the filter membrane 2 can be, for example, 0.01 to 0.4 μm.

[0026] The support plate 3 is a plate-like member configured to be able to join the filter membrane 2. The member constituting the support plate 3 is not particularly limited, and for example, it may be an ABS resin, etc. The support plate 3 is provided with a nozzle 31 for taking out the filtered water outside the membrane cartridge 1.

[0027] The support plate 3 has a first joint portion 32 and a second joint portion 33 provided on the outer edge 35 side of the first joint portion 32 (FIGS. 2 and 3). The first joint portion 32 and the second joint portion 33 are the portions joined to the filter membrane 2 when the filter membrane 2 is joined to the support plate 3. The first joint portion 32 protrudes from the filtration surface (the surface on which the filter membrane 2 extends), and the second joint portion 33 retreats from the filtration surface. In correspondence with the fact that one filter membrane 2 is joined to each of the two surfaces of the support plate 3, the first joint portion 32 and the second joint portion 33 are provided on both surfaces of the support plate 3.

[0028] The first joint portion 32 protrudes with respect to the reference surface 34 on the support plate 3, that is, in the direction along the Z axis in FIG. 1. In the present embodiment, the protruding distance (height) of the first joint portion 32 with respect to the reference surface 34 is 0.15 mm, and the width of the first joint portion 32 is 2.6 mm. The reference surface 34 refers to a surface among the surfaces extending in the outer frame portion of the support plate 3 that is not a portion intentionally provided to protrude such as the first joint portion 32. Further, the first joint portion 32 is provided over the entire circumference in the surface direction of the support plate 3.

[0029] The second joint portion 33 is provided so as to retreat from the reference surface 34. In the present embodiment, the retreat distance (depth) of the second joint portion 33 with respect to the reference surface 34 is 0.15 mm at the location where the filter membrane 2 exists and 0.05 mm at the location where the filter membrane 2 does not exist, and the upper surface of the filter membrane 2 and the location where the filter membrane 2 does not exist are flush with each other in the second joint portion 33. Further, the width of the second joint portion 33 is 5 mm. Therefore, the protruding distance (height) of the first joint portion 32 with reference to the location where the filter membrane 2 of the second joint portion 33 exists is 0.30 mm.

[0030] Further, at the edge portion of the second joint portion 33 on the outer edge 35 side of the support plate 3, a convex portion 33a protruding toward the outer edge 35 side of the support plate 3 and a concave portion 33b recessed from the outer edge 35 side are alternately provided (FIG. 2). In FIG. 2, an example is shown in which the shape along the surface direction of the second joint portion 33 is zigzag, but it is sufficient that the convex portion 33a and the concave portion 33b are alternately provided, and for example, it may be wavy.

[0031] In the membrane cartridge 1, the outer edge portion 21 of the filter membrane 2 is joined to the support plate 3 in the region between the convex portion 33a and the concave portion 33b of the second joint portion 33. By joining the outer edge portion 21 of the filter membrane 2 to the second joint portion 33, it is possible to prevent the outer edge portion 21 of the filter membrane 2 from moving under the stress of a water flow or the like during the use of the membrane cartridge 1. Such movement may cause breakage of the filter membrane 2 and detachment of the joint between the filter membrane 2 and the support plate 3, and thus it is necessary to avoid this.

[0032] Further, the portion inside the outer edge portion 21 of the filter membrane 2 is joined to the support plate 3 at the first joint portion 32. Since the first joint portion 32 is provided over the entire circumference in the plane direction of the support plate 3, a water seal is formed over the entire circumference in the plane direction of the support plate 3 by the joining of the filter membrane 2 and the first joint portion 32. By this water seal, the primary side and the secondary side of the filter membrane 2 are isolated. From the viewpoint of reliably forming the water seal, the joining of the filter membrane 2 and the support plate 3 is preferably performed by thermal fusion or ultrasonic fusion, and particularly preferably by thermal fusion. In addition, since there is no recessed portion at the first joint portion, vibration of the filter membrane with the raised portion around the recessed portion as a fulcrum does not occur, and a membrane cartridge 1 having no structure (for example, a raised portion) that can induce breakage of the filter membrane 2 can be realized.

[0033] 〔Manufacturing method of membrane cartridge〕 Next, a method for manufacturing the membrane cartridge 1 according to the present embodiment will be described (Figs. 4 to 6). The manufacturing method of the membrane cartridge 1 according to the present embodiment includes an arrangement step and a joining step. Hereinafter, the case where the first filter membrane 2 is joined to the support plate 3 to which the filter membrane 2 is not joined will be described as an example. In order to distinguish between the two surfaces of the support plate 3, the surface to which the filter membrane 2 is joined in the procedure described below is referred to as surface 3A.

[0034] (1) Arrangement step The arrangement step is a step of arranging the filter membrane 2 on the pre-joining support plate 30 on which the reference surface 34 and the first joint portion 32 are provided in advance (Figs. 4 and 5). The difference between the pre-joining support plate 30 used here and the above-described support plate 3 is that the second joint portion 33 is not provided on the pre-joining support plate 30, and an open space where the second joint portion 33 is to be provided exists as a part of the reference surface 34 (Fig. 5). The pre-joining support plate 30 becomes the support plate 3 when the second joint portion 33 is provided in the joining step as described later.

[0035] In the arrangement step, first, the pre-joining support plate 30 is placed on the gantry 5. At this time, the surface 30A, which is the surface that becomes the surface 3A of the support plate 3 after joining, faces upward (Fig. 4).

[0036] Next, the filter membrane 2 is placed on the pre - joining support plate 30 (surface 30A) placed on the pedestal. Here, the positional relationship in the plane direction between the filter membrane 2 and the pre - joining support plate 30 is set such that the outer edge portion 21 of the filter membrane 2 abuts on a part of the reference plane 34 where the second joining portion 33A is to be provided.

[0037] (2) Joining process In the joining process, the pressing member 4 is pressed from above the filter membrane 2 placed on the pre - joining support plate 30 (surface 30A) to retract a part of the reference plane 34 to form the second joining portion 33, and the joining of the filter membrane 2 and the support plate 3 is completed at the first joining portion 32 and the second joining portion 33 (Fig. 6). In this embodiment, the pressing member 4 is heated at a set temperature of 170 - 190°C, and thus in the membrane cartridge 1, the filter membrane 2 and the support plate 3 are heat - fused (an example of joining). Note that the means for heating the pressing member 4 may be a known means. For example, known heating means such as an electric heater or a steam pipe may be provided inside the pressing member 4.

[0038] The pressing member 4 has a first portion 41 facing the first joining portion 32A and a second portion 42 facing the open space (a part of the reference plane 34) where the second joining portion 33A is to be provided. The first portion 41 is provided retracted from the second portion 42 (Fig. 6). More specifically, the retraction distance of the first portion 41 with respect to the second portion 42 is 0.3 mm, which is smaller than 0.5 mm, which is the protruding distance (height) of the first joining portion 32 from the reference plane 34 in the pre - joining support plate 30. Corresponding to the fact that the first joining portion 32A is provided over the entire circumference in the plane direction of the support plate 3, the first portion 41 has a shape forming a closed curve when viewed from below in Fig. 6. Also, the second portion 42 is provided in a zig - zag shape corresponding to the formation of the second joining portion 33A in a zig - zag shape.

[0039] When the pressing member 4 is pressed from above the filter membrane 2 disposed on the pre - joining support plate 30 (surface 30A), first, the filter membrane 2 is pressed against the first joining portion 32A by the first part 41. Subsequently, with a delay of 0.2 mm, the filter membrane 2 is pressed against the reference surface 34 outside the first joining portion 32A by the second part 42, and a part of the reference surface 34 retreats to form the second joining portion 33A (FIG. 6). Thereby, the first joining portion 32A can be reliably formed. Further, since the second part 42 has a large area, it is difficult to push in and serves as a brake, and excessive pressing can be avoided. As a result, excessive deformation of the first joining portion 32A during joining (welding) can be avoided, so that breakage or peeling of the filter membrane 2 that may occur starting from such deformation is less likely to occur.

[0040] In the present embodiment, since the second part 42 is provided in a zigzag shape, a positional relationship in the plane direction between the filter membrane 2 and the pre - joining support plate 30 can be realized such that the outer edge portion 21 of the filter membrane 2 abuts on the second part 42 when the pressing member 4 is pressed against the pre - joining support plate 30, and a tolerance range occurs. Therefore, variations in the dimensions of the filter membrane 2 and misalignment in the plane direction between the filter membrane 2 and the pre - joining support plate 30 can be tolerated to some extent, so that excessive labor is not required for adjusting the positional relationship between the filter membrane 2 and the pre - joining support plate 30 in the placement process.

[0041] Note that the method of joining the second filter membrane 2 to the opposite surface is the same as the above - mentioned placement process and joining process.

[0042] 〔Other Embodiments〕 Finally, other embodiments of the method for manufacturing the membrane cartridge according to the present invention will be described. Note that the configurations disclosed in each of the following embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs.

[0043] In the above embodiment, the second bonding portion 33 has a convex portion 33a and a concave portion 33b. However, the shape of the second bonding portion according to the present invention is not limited to the above example, and may be, for example, a band-like shape. In addition, the portion where the outer edge portion of the filtration membrane and the second bonding portion are bonded is not limited as long as it is within the range of the second bonding portion.

[0044] In the above embodiment, the pressing member 4 is configured such that the retraction distance of the first portion 41 from the second portion 42 is smaller than the height of the first joint portion 32 from the reference plane 34. However, in the manufacturing method of the membrane cartridge according to the present invention, the shape of the pressing member is not particularly limited.

[0045] In the above embodiment, an example has been described in which the pressing member 4 is heated and the filtration membrane 2 and the support plate 3 are welded together. However, in the manufacturing method of the membrane cartridge according to the present invention, the method of joining the filtration membrane and the support plate is not particularly limited.

[0046] Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereto. A person skilled in the art would easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. [Industrial Applicability]

[0047] The present invention can be utilized, for example, as a method for manufacturing a membrane cartridge to be mounted in a submerged membrane filtration device. [Explanation of symbols]

[0048] 1: Membrane cartridge 2: Filtration membrane 21: Outer edge of the filtration membrane 3: Support plate 3A: (the surface on which the filtration membrane is placed) 30: Support plate before joining 30A: (the surface where the filtration membrane is disposed) 31: Nozzle 32: First joint 32A: First joint (on the side of surface 3A) 33: Second joint 33A: Second joint (on the side of surface 3A) 33a: Convex part 33b: Concave part 34: Reference plane 35: Outer edge of the support plate 4: Pressing member 41: First part 42: Second part 5: Stand

Claims

1. A membrane cartridge comprising a filtration membrane and a support plate, wherein the support plate is provided with a reference surface, a first joint portion protruding from the reference surface, and a second joint portion recessed from the reference surface; the second joint portion is provided on the outer edge side of the support plate with respect to the first joint portion; at least a part of the outer edge of the filtration membrane is joined to the support plate at the second joint portion; and an inner side of the outer edge of the filtration membrane is joined to the support plate in a region including the top of the first joint portion.

2. The membrane cartridge according to claim 1, wherein the edge portion of the second joint portion on the outer edge side of the support plate is alternately provided with a convex portion convex toward the outer edge side of the support plate and a concave portion concave from the outer edge side.

3. The membrane cartridge according to claim 2, wherein the outer edge of the filtration membrane is joined to the support plate in a region between the convex portion and the concave portion of the second joint portion.

4. A method for manufacturing a membrane cartridge in which a filtration membrane is joined to a support plate having a reference surface, a first joint portion protruding from the reference surface, and a second joint portion recessed from the reference surface, comprising: an arranging step of arranging the filtration membrane on a pre-joining support plate in which the reference surface and the first joint portion are provided in advance; a joining step of pressing a pressing member from above the filtration membrane arranged on the pre-joining support plate to retract a part of the reference surface to form the second joint portion, and completing the joining of the filtration membrane and the support plate at the first joint portion and the second joint portion, wherein, in the pressing member, a first portion facing the first joint portion is provided to be recessed more than a second portion forming the second joint portion.

5. The method for manufacturing a membrane cartridge according to claim 4, wherein the retraction distance of the first part with respect to the second part is smaller than the height of the first joint from the reference surface.

6. The method for manufacturing a membrane cartridge according to claim 5, wherein the pressing member is heated.

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