WO2015166656A1

WO2015166656A1 - Separation membrane structure and separation membrane structure module

Info

Publication number: WO2015166656A1
Application number: PCT/JP2015/002258
Authority: WO
Inventors: 小泉　洋; 洋一郎水谷
Original assignee: 日本特殊陶業株式会社
Priority date: 2014-04-30
Filing date: 2015-04-27
Publication date: 2015-11-05
Also published as: JP6449859B2; JPWO2015166656A1

Abstract

A separation membrane structure is provided with: a base material formed from a porous inorganic material and provided with a first end surface and a second end surface in the longitudinal direction and a flow path linking the first end surface and the second end surface and wherein a fluid to be treated circulates; a separation membrane formed on the inside wall surface or the outside wall surface of the flow path; and an alkali resistant sealing layer formed at least on the first and second end surfaces.

Description

Separation membrane structure and separation membrane structure module

Reference to related applications

This application claims priority based on Japanese Patent Application No. 2014-93320 filed on April 30, 2014, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a separation membrane structure including a separation membrane.

Some separation membrane structures include a columnar base material having a porous structure and a separation membrane formed on an inner wall surface of a flow path parallel to the axial direction of the base material. Separation membrane structures are used in various applications such as dust collection, sterilization, purification, dehydration, liquid separation, and gas separation. Conventionally, in a separation membrane structure, a glass sealing layer is formed on a surface where a fluid to be treated is introduced and a surface where a concentrated fluid after treatment is discharged (see, for example, Patent Document 1). .

JP 2007-237109 A

There are cases where the fluid to be treated with the separation membrane structure is an alkaline fluid, or the separation membrane structure is subjected to alkali cleaning using caustic soda or the like. Since glass has low alkali resistance, the glass sealing layer of the separation membrane structure may be dissolved and peeled off by repeating the treatment of an alkaline fluid to be treated or repeating alkali washing. Further, the separation membrane structure is used by being stored in the housing via a sealing material such as an O-ring. If the surface of the glass sealing layer becomes rough due to alkali cleaning or the like, a gap is generated between the separation membrane structure and the O-ring, which may cause leakage of the fluid to be processed. Therefore, a technique for improving the durability of the seal layer of the separation membrane structure has been desired. In addition, the conventional separation membrane structure has been desired to reduce costs, save resources, facilitate manufacturing, and improve performance.

The present invention has been made to solve the above problems, and can be realized as the following modes.

(1) According to one aspect of the present invention, a separation membrane structure is provided. The separation membrane structure includes a first end surface in the longitudinal direction, a second end surface, and a flow path that communicates the first end surface and the second end surface and through which a fluid to be treated flows. A substrate made of a porous inorganic material, a separation membrane formed on the inner wall surface or outer wall surface of the flow path, and a seal layer having high alkali resistance formed at least on the first and second end surfaces. May be. According to the separation membrane structure of this embodiment, since the seal layer has high alkali resistance, deterioration due to treatment of an alkaline fluid to be treated and alkali washing can be suppressed, and durability of the seal layer can be improved.

(2) In the separation membrane structure of the above aspect, the sealing layer may have a surface roughness Ra of 0.5 μm or less after being immersed in an aqueous solution of sodium hydroxide at 80 ° C. and 4% by weight for 1000 hours. . The surface roughness Ra shall be measured at randomly selected locations in accordance with JIS B 0601 (1994) under the conditions of a measurement length of 2.0 mm and a cutoff wavelength of 0.25 mm. With such a seal layer, degradation due to treatment of an alkaline fluid to be treated and alkali cleaning can be suppressed, and durability of the seal layer can be improved.

(3) In the separation membrane structure according to the above aspect, the sealing layer may have a ratio of a change amount of the surface roughness Ra before and after the immersion to a surface roughness Ra before the immersion of less than 0.5. . With such a seal layer, degradation due to treatment of an alkaline fluid to be treated and alkali cleaning can be suppressed, and durability of the seal layer can be improved.

(4) In the separation membrane structure according to the above aspect, the sealing layer may have a static friction coefficient μs of less than 0.5. The static friction coefficient μs can be measured using a Bowden label type measuring instrument (steel ball having a diameter of 8 mm, load 1.0 kg, linear velocity 0.27 mm / sec). When this separation membrane structure is supported and used in a casing via a seal member, if the seal member is disposed on the seal layer, the surface of the seal layer is smooth, so the separation membrane structure and the seal member Slidability can be improved. As a result, the sealing performance between the separation membrane structure and the housing can be improved, and leakage of the fluid to be processed can be suppressed. In addition, the possibility of twisting of the seal member due to the separation membrane structure is reduced, and work efficiency when the separation membrane structure is stored in the housing can be improved.

(5) In the separation membrane structure according to the above aspect, the seal layer may be formed of a fluorine-based resin. Even in this case, a sealing layer having alkali resistance and a smooth surface can be easily obtained.

(6) In the separation membrane structure of the above aspect, the seal layer may be formed of tetrafluoroethylene or a copolymer fluororesin compound having tetrafluoroethylene as a basic molecular skeleton. Even in this case, a sealing layer having alkali resistance and a smooth surface can be easily obtained.

(7) In the separation membrane structure according to the above aspect, the sealing layer includes the first and second end surfaces of the base material, an outer peripheral surface near the first and second end surfaces, and the first and second end surfaces. And the sealing layer formed on the outer peripheral surface and the separation membrane may be formed continuously from the sealing layers formed on the first and second end surfaces. If it does in this way, the adhesion area of a sealing layer and a base material can be ensured large, and a sealing performance can be improved. Further, when the separation membrane structure is supported and used in the casing via the sealing member, if the sealing member is disposed on the sealing layer formed on the side surface, the sealing property between the separation membrane structure and the casing is improved. This can improve the leakage of the fluid to be processed.

(8) In the separation membrane structure according to the above aspect, a base corner formed by the first end face and the second end face of the base, and the outer peripheral face and the inner wall face of the flow path. And the seal layer corner of the seal layer formed on the corner of the base has a roundness, and the radius of curvature Rs of the corner of the seal layer is more than the radius of curvature Rb of the base of the base. It can be large. If it does in this way, the contact area of a sealing layer and a base material can be enlarged, and the adhesiveness of a sealing layer will improve. Further, it is preferable that the corners have roundness because the flow of the fluid to be processed becomes good.

(9) According to one aspect of the present invention, a separation membrane structure module is provided. The separation membrane structure module may include the separation membrane structure of the above-described form and a housing that stores the separation membrane structure inside. According to this separation membrane structure module, since the alkali resistance of the seal layer of the separation membrane structure is high, the durability of the seal layer is improved. As a result, the durability of the separation membrane structure module is improved.

(10) In the separation membrane structure module of the above aspect, the separation membrane structure is supported by supporting the vicinity of the first and second end surfaces of the outer peripheral surface of the base material through a sealing member made of an elastic material. The seal layer is housed in a housing, and the seal layer contacts the seal member from the first and second end surfaces, the separation membrane in the vicinity of the first and second end surfaces, and the first and second end surfaces of the outer peripheral surface. You may cover at least the position. In this case, when the seal member is disposed on the seal layer of the separation membrane structure and the surface of the seal layer is smooth, the slidability between the separation membrane structure and the seal member can be improved. . As a result, the sealing performance between the separation membrane structure and the housing can be improved, and leakage of the fluid to be processed can be suppressed. In addition, the possibility of twisting of the seal member due to the separation membrane structure is reduced, and work efficiency when the separation membrane structure is stored in the housing can be improved.

The present invention can be realized in various forms, for example, in the form of an apparatus including a separation membrane structure, a method of manufacturing a separation membrane structure, a method of manufacturing a separation membrane structure module, and the like. Can do.

It is a cutting part end view showing typically the structure of the separation membrane structure module as an embodiment of the present invention. It is explanatory drawing which shows the external appearance of a separation membrane structure. It is explanatory drawing which shows the external appearance of a base material. It is a partial expanded end view which expands and shows the cross-sectional structure of a separation membrane structure. It is a flowchart which shows the flow of the formation process of the seal layer in embodiment. It is a graph which shows the test result of alkali resistance using the separation membrane structure of embodiment.

A. Embodiment:
A-1. Separation membrane structure module structure:
FIG. 1 is an end view of a cut portion schematically showing the structure of a separation membrane structure module as an embodiment of the present invention. FIG. 1 illustrates a cut surface including a central axis of a separation membrane structure 20 formed in a substantially cylindrical shape. As shown in FIG. 1, the separation membrane structure module 100 mainly includes a separation membrane structure 20 and a housing 30.

As shown in FIG. 1, the separation membrane structure 20 includes a base material 22, a separation membrane 24, a first seal layer 28, and a second seal layer 29. Hereinafter, the first seal layer 28 and the second seal layer 29 are collectively referred to as seal layers 28 and 29. FIG. 2 is an explanatory view showing the appearance of the separation membrane structure. As shown in FIG. 2, the separation membrane structure 20 has a substantially cylindrical outer shape, and has a plurality of penetrations penetrating from one end face (first end face) to the other end face (second end face). A hole (flow path 26) is formed. In FIG. 2, O-

rings

37 and 38 used when storing the separation membrane structure 20 in the housing 30 are illustrated by broken lines. In the separation membrane structure 20, the seal layers 28 and 29 are formed on the seal layers 28 and 29 so that the O-

rings

37 and 38 are disposed, respectively. The O-

rings

37 and 38 in this embodiment correspond to the sealing member in the claims.

FIG. 3 is an explanatory view showing the appearance of the base material. As shown in FIG. 3, the base material 22 includes a first end surface 221, a second end surface 222, and an outer peripheral surface 223 having a substantially circular shape, and is formed in a substantially cylindrical shape having a total length of about 1000 mm. A porous body made of The base material 22 is formed with a plurality of flow paths 26 through which the liquid to be processed to be processed by the separation membrane structure 20 is communicated with the first end surface 221 and the second end surface 222. In this embodiment, a substrate having a surface roughness Ra of 2 μm is used. However, the surface roughness is not limited to this, and for example, substrates having various surface roughness such as 5 μm, 1 μm, and 0.5 μm are used. Can do.

The separation membrane 24 is an alumina porous membrane having a large number of micropores having an average pore diameter smaller than that of the base material 22. As shown in FIG. 1, the separation membrane 24 is formed on the surface (inner wall surface) of the flow path 26 formed in the base material 22.

The first seal layer 28 includes a first end surface 221 of the base material 22, the vicinity of the first end surface 221 of the separation membrane 24, and a first end surface of the outer peripheral surface 223, as illustrated in FIG. 221 and the vicinity thereof are covered. The first seal layer 28 is formed on the inner surface of the separation membrane 24 and the outer peripheral surface 223 of the base material 22 continuously from the first end surface 221 of the base material 22. As shown in FIG. 1 during blowing, the second seal layer 29 includes the second end surface 222 of the base material 22, the vicinity of the second end surface 222 of the separation membrane 24, and the second end surface of the outer peripheral surface 223. The vicinity of 222 is covered. The second seal layer 29 is formed on the inner surface of the separation membrane 24 and the outer peripheral surface 223 of the base material 22 continuously from the second end face 222 of the base material 22. In the present embodiment, the first seal layer 28 is in the range from the first end surface 221 to about 15 mm on the outer peripheral surface 223, and the second seal layer 29 is about from the second end surface 222 in the outer peripheral surface 223. Each of the ranges up to 15 mm is covered. The range in which the sealing layers 28 and 29 cover the outer peripheral surface 223 is not limited to this embodiment, and the vicinity of the first and second end surfaces 221 and 222 may be covered. The vicinity means, for example, less than 15% of the entire length of the base material 22. It is preferable to cover the outer peripheral surface 223 with the first seal layer 28 and the second seal layer 29 until at least the position where the O-

rings

37 and 38 are disposed.

FIG. 4 is a partially enlarged end view showing an enlarged cross-sectional configuration of the separation membrane structure 20. In FIG. 4, the portion (second seal layer 29 side) enlarged during blowing in FIG. 1 is further enlarged. 4A shows the outer peripheral surface 223 side of the base material 22 during the blowing of FIG. 1, and FIG. 4B shows the flow path 26 side (the side on which the separation membrane 24 is formed) of the base material 22. , Illustrated.

In the separation membrane structure 20 of the present embodiment, a corner formed by the end face (first end face 221 and second end face 222) of the base material 22, the outer peripheral face 223 and the inner wall face 226 of the flow path 26. (Hereinafter also referred to as a base material corner) has roundness. And the corner | angular part (henceforth a sealing layer corner | angular part) of the sealing layers 28 and 29 formed on the base-material corner | angular part also has roundness. Hereinafter, based on the cut surface (FIG. 4) including the central axis of the separation membrane structure 20 formed in a substantially cylindrical shape, the radius of curvature of the corners of the base material 22 and the second seal layer 29 will be described. As shown in FIG. 4A, the base corner portion RC1 formed by the second end face 222 and the outer peripheral face 223 of the base 22 has a roundness. In the cut surface shown in FIG. 4A, the base corner portion RC1 of the base 22 is composed of a first straight line L11, a second straight line L12, and a curve CL1. In FIG. 4A, both ends of the curve CL1 are a point P11 and a point P13. When the first virtual circle C1 passing through any three points on the curve CL1 (P11, P12, and P13 in FIG. 4A) is drawn, the radius R1 of the first virtual circle C1 is set to the base corner portion RC1. The curvature radius is Rb1. On the other hand, the seal layer corner portion RC3 which is the corner portion of the second seal layer 29 formed on the substrate corner portion RC1 of the substrate 22 also has a roundness. In the cut surface (FIG. 4A), the seal layer corner portion RC3 of the second seal layer 29 is configured by a first straight line L31, a second straight line L32, and a curve CL3. In FIG. 4A, both ends of the curve CL3 are a point P31 and a point P33. When the third virtual circle C3 passing through any three points on the curve CL3 (P31, P32, and P33 in FIG. 4A) is drawn, the radius of the third virtual circle C3 is R3, and the seal layer corner portion RC3. It is assumed that the radius of curvature Rs3. In the separation membrane structure 20 of the present embodiment, the radius R3> the radius R1. That is, the curvature radius Rs3 of the seal layer corner portion RC3 of the second seal layer 29 formed on the substrate corner portion RC1 of the substrate 22 is larger than the curvature radius Rb1 of the substrate corner portion RC1 of the substrate 22.

Further, as shown in FIG. 4B, the base material corner portion RC2 formed by the second end face 222 of the base material 22 and the inner wall surface 226 of the flow path 26 has a roundness. In the cut surface shown in FIG. 4B, the base-material corner portion RC2 of the base material 22 is composed of a first straight line L21, a second straight line L22, and a curve CL2. In FIG. 4B, both ends of the curve CL2 are a point P21 and a point P23. When the second virtual circle C2 passing through any three points (P21, P22, and P23 in FIG. 4B) on the curve CL2 is drawn, the radius R2 of the second virtual circle C2 is set to the base corner portion RC2. The curvature radius is Rb2. On the other hand, the seal layer corner portion RC4 which is the corner portion of the second seal layer 29 formed via the separation membrane 24 on the substrate corner portion RC2 of the substrate 22 is also rounded. In the cut surface (FIG. 4B), the seal layer corner portion RC4 of the second seal layer 29 is composed of a first straight line L41, a second straight line L42, and a curve CL4. In FIG. 4B, both ends of the curve CL4 are a point P41 and a point P43. When the fourth virtual circle C4 passing through any three points on the curve CL4 (P41, P42, and P43 in FIG. 4B) is drawn, the radius R4 of the fourth virtual circle C4 is set to the seal layer corner portion RC4. The curvature radius is Rs4. In the separation membrane structure 20 of the present embodiment, the radius R4> the radius R2. That is, the radius of curvature Rs4 of the seal layer corner RC4 of the second seal layer 29 formed on the base corner RC2 of the base 22 is larger than the radius of curvature Rb2 of the base corner RC2 of the base 22. Here, the curvature radii Rb1 and Rb2 in the base material 22 may be the same or different. Similarly, the radii of curvature Rs3 and Rs4 in the second seal layer 29 may be the same or different.

In the above description, the portion (second seal layer 29 side) shown during blowing in FIG. 1 has been described. However, the base material of the base material 22 extends over the entire circumference of the second end surface 222 of the separation membrane structure 20. The curvature radius Rs3 of the seal layer corner portion RC3 of the second seal layer 29 formed on the corner portion RC1 is larger than the curvature radius Rb1 of the substrate corner portion RC1 of the substrate 22. The curvature radius Rs4 of the seal layer corner portion RC4 of the second seal layer 29 formed on the substrate corner portion RC2 of the base material 22 over the entire circumference of the single flow path 26 is the base material 22. Larger than the radius of curvature Rb2 of the base corner portion RC2. Further, this relationship is established for all the flow paths 26 included in the separation membrane structure 20. Also on the first end surface 221 side (first seal layer 28 side) of the base material 22, the corner portion has the same shape, and the curvature radius of the corner portion of the base material 22 is formed on the corner portion. Smaller than the radius of curvature of the first seal layer 28 formed. The radius of curvature described above can be obtained using an image obtained by imaging the cut surface of the separation membrane structure 20 with an optical microscope, for example, at a magnification of 100 times. The curvature radii Rb1 and Rb2 in the present embodiment correspond to the curvature radius Rb in the claims, and the curvature radii Rs1 and Rs2 correspond to the curvature radius Rs in the claims. In other embodiments, all the corners of the substrate 22 may not have roundness, and at least one corner of the substrate has roundness and has roundness. The seal layer corner portion of the seal layer formed on the substrate corner portion is rounded, and the radius of curvature of the seal layer may be larger than the curvature radius of the corresponding substrate.

Thus, in the separation membrane structure 20 of the present embodiment, the curvature of the corners of the corresponding seal layers 28 and 29 is determined from the radius of curvature Rb of the corners of the base material 22 (Rb1 and Rb2 are collectively referred to as Rb). The radius Rs (Rs3 and Rs4 are collectively referred to as Rs) is large. When the radius of curvature Rs of the corners of the sealing layers 28 and 29 is smaller than the radius of curvature Rb of the corners of the base material 22, the corners of the sealing layer are sharper than the corners of the base material 22. Therefore, there is a possibility that the fluid to be processed does not easily flow into the separation membrane structure 20 due to the resistance due to the corners of the separation membrane structure 20. On the other hand, in the separation membrane structure 20 of the present embodiment, when the fluid to be treated flows into the flow path 26 of the separation membrane structure 20, the resistance is small and the fluid is easy to flow. Also when flowing out from the separation membrane structure 20 through 26, the opening area of the flow path 26 is large, so that it is easy to flow out and the flow of the fluid to be treated is improved. Furthermore, since the radius of curvature Rs of the corners of the seal layers 28 and 29 is larger than the radius of curvature Rb of the corners of the base material 22, the contact area of the seal layers 28 and 29 with respect to the base material 22 is increased. Adhesion is also improved. In FIG. 4, the virtual circle is drawn using three points including the points at both ends of each of the curves CL1 to CL4 constituting the roundness of each corner. A radius of curvature may be obtained by drawing a virtual circle passing through three points.

In this embodiment, the seal layers 28 and 29 are formed using PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) having high alkali resistance. In this embodiment, “high alkali resistance” means that the surface roughness Ra after immersion for 1000 hours in an aqueous solution of sodium hydroxide at 80 ° C. and 4% by weight is 0.5 μm or less, and the surface before and after immersion. It means that the ratio of the amount of change in the roughness Ra to the surface roughness Ra before immersion is less than 0.5. The surface roughness Ra is measured at randomly selected locations in accordance with JIS B 0601 (1994) under the conditions of a measurement length of 2.0 mm and a cutoff wavelength of 0.25 mm. Further, since PFA has a small static friction coefficient μs, the surfaces of the seal layers 28 and 29 are smooth. In the present embodiment, “the surface is smooth” means that the coefficient of static friction μs is less than 0.5. The static friction coefficient μs is measured using a Bowden label type measuring instrument (steel ball having a diameter of 8 mm, load 1.0 kg, linear velocity 0.27 mm / sec).

In the present embodiment, the seal layers 28 and 29 also flow into the pores of the base material 22 and the separation membrane 24. Therefore, the adhesion between the base material 22 and the separation membrane 24 and the seal layers 28 and 29 is improved as compared with the case where the base material 22 and the separation membrane 24 do not flow into the pores. As a result, even when an impact is applied to the separation membrane structure 20 from the outside, it is possible to suppress the seal layers 28 and 29 from peeling from the base material 22 and the separation membrane 24. Whether or not the seal layers 28 and 29 are flowing into the pores of the base material 22 and the separation membrane 24 is visually determined using an optical microscope, for example, an image captured at a magnification of 100 times. be able to.

The housing 30 is a hollow metal container having a space for accommodating the separation membrane structure 20 therein, and as shown in FIG. 1, an inlet 31 for introducing the liquid to be treated, and the separation membrane structure 20. The first filtrate outlet 33, the second filtrate outlet 34, and the separation membrane structure 20 that discharge the filtrate filtered by the first and second separation membrane structures 20 discharge the concentrated liquid from which the liquid to be treated is discharged. And an outlet 32. In the separation membrane structure 20, an annular metal blocking member 35 is fitted in the vicinity of the first end surface 221 of the outer peripheral surface 223 via the O-ring 37, and the O 2 is adjacent to the second end surface 222 of the outer peripheral surface 223. An annular metal blocking member 36 is fitted through the ring 38. The separation membrane structure 20 is supported and accommodated in the housing 30 via O-

rings

39 and 40 between the inner wall of the housing 30 and the

metal blocking members

35 and 36. Since the separation membrane structure 20 is housed in the housing 30 in this way, the space in the housing 30 is a first space surrounded by the first end surface 221 and the inner wall of the housing 30, and the outer peripheral surface 223. And a second space surrounded by the inner wall of the housing 30 and a third space surrounded by the second end surface 222 and the inner wall of the housing 30 while being sealed.

When the liquid to be processed is introduced into the first space in the housing 30 from the inlet 31, the liquid to be processed can pass through the separation membrane 24 while flowing through the flow path 26 of the separation membrane structure 20. Only flows through the separation membrane 24 and the base material 22 and flows out into the second space, and flows out from the first filtrate port 33 and the second filtrate port 34 as filtrate. The liquid to be processed is concentrated by the separation membrane structure 20 and flows out into the third space, and is discharged from the concentrated liquid discharge port 32 as a concentrated liquid.

In the present embodiment, as described above, since the vicinity of the first end surface 221 and the second end surface 222 of the separation membrane structure 20 is covered with the seal layers 28 and 29, the liquid to be processed passes through the separation membrane 24. Therefore, it is possible to prevent the processing efficiency from being lowered by passing through only the base material 22 and mixing in the filtrate, or by mixing the filtrate passing through the separation membrane 24 into the concentrated liquid via the base material 22. can do. In the present embodiment, the seal layers 28 and 29 are formed on the first end surface 221 of the base material 22, the vicinity of the first end surface 221 of the separation membrane 24, and the vicinity of the first end surface 221 of the outer peripheral surface 223. However, the range in which the seal layers 28 and 29 are formed is not limited to this embodiment. The sealing layers 28 and 29 may be formed at least on the first end surface 221 and the second end surface 222 of the base material 22. Even if it does in this way, it can suppress that processing efficiency falls.

As shown in FIGS. 1 and 2, the seal layers 28 and 29 cover a part of the outer peripheral surface 223 of the base material 22, and the housings are formed on the seal layers 28 and 29 via O-

rings

37 and 38. It is supported in the body 30. Since the sealing layer has a smooth surface, the sealing properties between the separation membrane structure 20 and the O-

rings

37 and 38 are compared with the case where the sealing layers 28 and 29 do not cover the outer peripheral surface 223 of the base material 22. And the leakage of the liquid to be processed from the first space to the second space and the leakage of the filtrate from the second space to the third space can be suppressed.

A-2. Seal layer forming process:
FIG. 5 is a flowchart showing the flow of the sealing layer forming process in the present embodiment. First, the exposed surface of the separation membrane structure main body in which the separation membrane 24 is formed on the surface of the flow path 26 of the substrate 22 is washed and dried (step S12). The both ends 15 mm of the outer peripheral surface 223 of the base material 22 are left, and other portions are protected with a masking tape (step S16). Subsequently, a coating material (hereinafter referred to as “sealing layer forming coating material”) serving as a sealing layer is spray-coated on both ends of the separation membrane structure body (step S24). In this embodiment, the seal layer forming paint is mixed with a dispersion paint of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) to sufficiently disperse the powder component, through a wire mesh, and to collect aggregates and dust. The removed one was used. The spray coating was performed at an atomization pressure of 0.2 MPa using a spray gun having a nozzle diameter of 1.0 mm. Then, preliminary drying is performed for 10 minutes at room temperature (step S26), and drying is performed for 30 minutes with a hot air dryer at 80 ° C. (step S28). After peeling off the masking tape (step S30), baking is performed in a heat treatment furnace at 360 ° C. for 20 minutes (step S32). Thereby, as shown in FIG. 2, the 1st sealing layer 28 and the 2nd sealing layer 29 are formed.
In addition, before apply | coating a sealing layer forming coating material, you may apply | coat a base coating as a base treatment.

In the sealing layer forming process of the present embodiment, in step S16, both end portions of the outer peripheral surface 223 of the base material 22 are left about 15 mm, and other portions are protected with a masking tape. Therefore, the first sealing layer 28 that covers the first end surface 221 of the base material 22, the vicinity of the first end surface 221 of the separation membrane 24, and the vicinity of the first end surface 221 of the outer peripheral surface 223 can be formed. it can. At the same time, the second sealing layer 29 that covers the second end surface 222 of the base material 22, the vicinity of the second end surface 222 of the separation membrane 24, and the vicinity of the second end surface 222 of the outer peripheral surface 223 can be formed. it can. In the present embodiment, as shown in FIG. 2, when the separation membrane structure module 100 is configured, the O-ring 37 is disposed on the first seal layer 28 and the O-ring 38 is disposed on the second seal layer 29. As shown, the sealing layers 28 and 29 are formed.

A-3. Effects of the embodiment:
FIG. 6 is a graph showing the test results of alkali resistance using the separation membrane structure of this embodiment. FIG. 6 shows the results of an alkali resistance test performed on the separation membrane structure 20 of the present embodiment and the separation membrane structure using a glass sealing layer as a comparative example. In this embodiment and the comparative example, the number of samples is 20. In FIG. 6, the average value is shown, and the variation is indicated by a vertical line (whisker). As an alkali resistance test, after immersing the seal layer portion of the separation membrane structure of this embodiment and the comparative example in an aqueous solution of sodium hydroxide at 80 ° C. and 4% by weight for 100 hours, 200 hours, 500 hours, and 1000 hours. The surface roughness Ra was measured. The surface roughness Ra was measured at randomly selected locations according to JIS B 0601 (1994) under the conditions of a measurement length of 2.0 mm and a cutoff wavelength of 0.25 mm.

As shown in FIG. 6, in the separation membrane structure of the comparative example, the surface roughness Ra of the seal layer increases with the lapse of the immersion time, whereas in the separation membrane structure 20 of this embodiment, the surface roughness Ra of the sealing layer increases. Even when the time reached 1000 hours, the surface roughness Ra of the sealing layer was substantially the same as before immersion. The surface roughness Ra of the seal layer portion of the separation membrane structure with an immersion time of 1000 hours was 0.133 μm for the separation membrane structure 20 of the present embodiment and 0.686 μm for the separation membrane structure of the comparative example. The separation membrane structure 20 of the present embodiment can be said to have high alkali resistance because the surface roughness Ra of the seal layer after being immersed in the alkaline solution for 1000 hours is 0.5 μm or less. The ratio of the amount of change in the surface roughness Ra before and after immersion to the surface roughness Ra before immersion at the immersion time of 1000 hours is 52.3 in the separation membrane structure of the comparative example. In the separation membrane structure 20 of the form, it is 0.247. That is, the sealing layer of the separation membrane structure 20 of the present embodiment has an alkali resistance of a ratio of the change amount of the surface roughness Ra before and after the immersion to the surface roughness Ra before the immersion is less than 0.5. It can be said that it is expensive.

According to the separation membrane structure 20 of the present embodiment, the sealing layers 28 and 29 are formed using a PFA dispersion paint having high alkali resistance. Deterioration such as dissolution and peeling of the seal layers 28 and 29 is suppressed with respect to the treatment of the treatment liquid, and the durability of the seal layers 28 and 29 is improved.

Using the separation membrane structure (immersion time 1000 hours) used in the alkali resistance test, a separation membrane structure module was constructed and the sealing property with the O-ring was confirmed. The surface roughness Ra of the seal layer portion of the separation membrane structure with an immersion time of 1000 hours was 0.133 μm for the separation membrane structure of this embodiment and 0.686 μm for the separation membrane structure of the comparative example. The flow path of the separation membrane structure is sealed with a stopper, and as shown in FIG. 1, the separation membrane structure module is configured by being assembled in the housing 30 via an O-ring. Water was introduced from. Hereinafter, the separation membrane structure module using the separation membrane structure of the present embodiment (immersion time 1000 hours), the separation membrane structure module of the present embodiment, and the separation membrane structure of the comparative example (immersion time 1000 hours). The used separation membrane structure module is referred to as a comparative separation membrane structure module. In the separation membrane structure module of the comparative example, outflow of water was confirmed from the

filtrate ports

33 and 34. In this test, as described above, the flow path of the separation membrane structure is sealed. Therefore, the water introduced from the inlet 31 does not flow out of the

filtrate ports

33 and 34 through the separation membrane 24 and the base material 22 while flowing through the flow path. In the separation membrane structure module of the comparative example, the surface of the seal layer is roughened by being exposed to an alkaline environment for a long time, the sealability between the seal layer and the O-ring 37 is lowered, and the separation membrane structure and the O-ring 37 are It is considered that water has flowed into the second space from the first space through the space. On the other hand, in the separation membrane structure module of this embodiment, no outflow of water was confirmed from the

filtrate ports

33 and 34. The separation membrane structure module of the present embodiment ensures the sealability between the seal layer and the O-ring 37 because the surface roughness of the seal layer hardly changes even when used in an alkaline environment for a long time. The airtightness of each space in 30 was able to be ensured.

Further, the static friction coefficient μs of the seal layer portion of the separation membrane structure 20 of the embodiment was 0.09, and the static friction coefficient μs of the seal layer portion of the separation membrane structure of the comparative example described above was 0.60. These are the results of measurement using a Bowden label type measuring device (8 mm diameter steel ball, load 1.0 kg, linear velocity 0.27 mm / sec). It can be said that the sealing layer of the separation membrane structure 20 of this embodiment has a static friction coefficient μs of less than 0.5 and a smooth surface.

According to the separation membrane structure 20 of the present embodiment, as shown in FIG. 2, when the separation membrane structure module 100 is configured, the O-ring 37 is on the first seal layer 28 and the O-ring 38 is the first. Seal layers 28 and 29 are formed so as to be disposed on the two seal layers 29. Since the sealing layers 28 and 29 are formed using a PFA dispersion paint and have a smooth surface, when the separation membrane structure module 100 is configured, the separation membrane structure 20 and the O-

rings

37 and 38 The sealing property can be improved, and leakage of the liquid to be processed can be suppressed.

Also, since the static friction coefficient of glass is larger than 0.5 and the sliding property is poor, the O-ring may be twisted when the separation membrane structure is assembled to the casing. When the O-ring is twisted, the sealing performance of each space in the housing is lowered. Therefore, the O-ring is twisted and reassembled. Therefore, the workability of the assembly work is reduced. On the other hand, the sealing layers 28 and 29 of the present embodiment have a static friction coefficient μs of 0.09, and the slidability between the separation membrane structure 20 and the O-

rings

37 and 38 is a case where a glass sealing layer is used. Since the separation membrane structure 20 is stored in the housing 30, the possibility that the O-

rings

37 and 38 are twisted by the separation membrane structure 20 is reduced. The airtightness of the space is improved. Further, when assembling the separation membrane structure 20 in the housing 30, it is possible to assemble without worrying about twisting of the O-

rings

37 and 38 by the separation membrane structure 20, so that the work efficiency is improved.

In addition, when processing a high-temperature liquid to be processed or cleaning a separation membrane structure using a high-temperature cleaning liquid, force is applied to the O-ring due to the difference in thermal expansion coefficient between the casing and the separation membrane structure. Sometimes. As described above, the separation membrane structure 20 of the present embodiment includes a PFA seal layer that has better slidability than glass. Therefore, even if a force is applied to the O-ring, the separation membrane structure 20 is less likely to be twisted. A decrease in sealing performance between the structure 20 and the O-

rings

37 and 38 is suppressed.

In the separation membrane structure 20 of the present embodiment, the first sealing layer 28 includes the first end surface 221 of the base material 22, the vicinity of the first end surface 221 of the separation membrane 24, and the first end surface of the outer peripheral surface 223. The second sealing layer 29 covers the second end surface 222 of the base material 22, the second end surface 222 of the separation membrane 24, and the vicinity of the second end surface 222 of the outer peripheral surface 223. It is covered. Compared with the case where the sealing layers 28 and 29 cover only the first and second end faces 221 and 222, a large bonding area between the sealing layers 28 and 29 and the base material 22 can be ensured, and the sealing performance is improved. Can be improved.

B. Variation:
The present invention is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve some or all of the above-described problems, or one of the above-described effects. In order to achieve part or all, replacement and combination can be appropriately performed. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate. For example, the following modifications are possible, for example.

B-1. First modification:
In the said embodiment, although PFA was illustrated as a material which forms the sealing layers 28 and 29, it is not limited to this. For example, copolymerized fluororesin compounds based on tetrafluoroethylene such as FEP (tetrafluoroethylene / hexafluoropropylene copolymer) and ETFE (tetrafluoroethylene / ethylene copolymer), tetrafluoroethylene alone, etc. Alternatively, a fluororesin may be used. Since the copolymer fluororesin compound having tetrafluoroethylene as the basic molecular skeleton has a relatively low melt viscosity and good fluidity at the time of melting, it is possible to form a thick seal layer without causing cracks. This is suitable when a sealing layer is formed on a surface having a large surface roughness. Further, even if it is a material other than the fluorine-based resin, the sealing layer has high alkali resistance and covers the first and second end surfaces 221 and 222 so that the fluid to be processed cannot pass through the inside of the base material excluding the flow path. Any material can be used as long as it can be formed. For example, polypropylene, cellulose acetate, methylpentene resin, or the like may be used. As the seal layer having high alkali resistance, for example, a layer having a surface roughness Ra of 0.5 μm or less after being immersed in an aqueous solution of sodium hydroxide at 80 ° C. and 4% by weight is preferable. More preferably, the surface roughness Ra after the immersion is 0.2 μm or less. Further, the ratio of the amount of change in surface roughness Ra before and after immersion to the surface roughness Ra before immersion is preferably less than 0.5. More preferably, the ratio is less than 0.3. In addition, a material capable of smoothly forming the surface of the seal layer is preferable. As the sealing layer having a smooth surface, for example, one having a static friction coefficient μs smaller than 0.5 is preferable. More preferably, the static friction coefficient μs is smaller than 0.1.

In addition, it is not preferable to use an elastomer as a material for forming the seal layers 28 and 29. This is because the elastomer has rubber elasticity, so the elastomeric sealing layer is soft and has poor sliding properties. When an elastomeric seal layer is used, the O-

rings

37 and 38 may bite into the seal layer and slip, and the O-

rings

37 and 38 may be deformed or twisted when the separation membrane structure is assembled to the housing 30. It is easy and the workability of the assembly work is reduced. In addition, since the sealing layer made of elastomer is not slidable, when the force is applied to the O-

rings

37 and 38 due to the difference in thermal expansion coefficient between the housing 30 and the separation membrane structure, the sealing layer is twisted. May occur or be damaged, the sealing performance between the seal layer and the O-

rings

37 and 38 may be reduced, and the fluid to be processed may leak. For example, although the fluorine-based elastomer has alkali resistance but has rubber elasticity, it is not preferable as a material for forming the seal layers 28 and 29.

A seal layer was formed using a fluororesin having alkali resistance and a fluoroelastomer, and the static friction coefficient was measured in order to compare the sliding property. Sample 1 is the separation membrane structure 20 (PFA seal layer) of the above embodiment, and sample 2 is a perfluoroether elastomer (fluorine elastomer) as a material for forming the seal layer. A separation membrane structure similar to the embodiment of the separation membrane structure 20 is produced. The static friction coefficient μs of the seal layer portions of Sample 1 and Sample 2 was measured using a Bowden label type measuring device (steel ball having a diameter of 12 mm, load 1.0 kg, linear velocity 0.2 mm / sec). The static friction coefficient μs of the seal layer portion (made of PFA) of sample 1 was 0.11, and the static friction coefficient μs of the seal layer portion of sample 2 (made of perfluoroether elastomer) was 0.67. From this result, it can be said that at least the perfluoroether elastomer has a poor sliding property because the static friction coefficient μs is 0.5 or more. Here, the static friction coefficient μs was measured using a fluorine-based elastomer (perfluoroether elastomer) as an example of the elastomer. However, since the elastomer generally has rubber elasticity, other elastomers similarly have a high static friction coefficient μs. Therefore, it can be said that it is at least 0.5 or more. Here, in the Bowden label type measuring instrument, a rigid sphere having a diameter of 12 mm and a linear velocity of 0.2 mm / sec are used. In the above embodiment, a rigid sphere having a diameter of 8 mm and a linear velocity of 0.27 mm / sec are used. However, the value of the static friction coefficient μs is substantially constant regardless of the size (diameter) of the hard sphere. Further, it is not preferable to move the linear velocity fast, and measurement is preferably performed at a linear velocity of 0.2 mm / sec or more and a linear velocity of 0.3 mm / sec or less. Within this range, a substantially constant value can be obtained as a measurement result.

B-2. Second modification:
In the above embodiment, the shape of the base material 22 is exemplified by the columnar shape in which the cross-sectional shape (cut surface perpendicular to the axis of the base material 22) is circular, but the shape of the base material is the same. It is not limited to. For example, the shape of the first and second end faces may be an elliptical cylinder. The shape of the first and second end faces may be a polygonal columnar shape (triangle, quadrangle, pentagon, hexagon, etc.). Furthermore, a plate shape may be sufficient. Further, the cross-sectional shape of the flow path may be an elliptical shape or a polygonal shape (triangle, quadrangle, pentagon, hexagon, etc.). Moreover, although the example provided with a some flow path was shown in the said embodiment, the number of flow paths is not limited to the said embodiment, It may be more or less than the said embodiment. For example, the number of flow paths may be one. When the number of flow paths is one, the shape of the base material can be formed in a tubular shape (tubular shape). When the number of channels is one, the separation membrane may be formed on the inner wall surface of the channel or on the outer wall surface of the channel. When the separation membrane is formed on the outer wall surface of the flow path, the separation membrane is formed on the outer peripheral surface of the base material.

B-3. Third modification:
In the said embodiment, although an example of the formation process of a sealing layer was shown, the formation process of a sealing layer is not limited to the said embodiment. What is necessary is just to select suitably drying temperature, time, the application method of a sealing layer formation coating material, etc. For example, as a coating method, dip coating, spin coating, electrostatic coating method, or the like may be used. The application of the seal layer forming paint may be repeated a plurality of times.

B-4. Fourth modification:
In the above embodiment, the porous body made of alumina is used as the base material 22 and the porous porous film made of alumina is used as the separation membrane 24. However, the material of the base material and the separation membrane is not limited to this. As the substrate, for example, a ceramic such as mullite, titania, zirconia, or a metal material such as stainless steel or titanium may be used. Separation membranes include solid-liquid separation membranes (microfiltration membranes (MF), nanofiltration membranes (NF), limiting membranes) made of mullite, titania, zirconia, zeolite, palladium, carbon, amorphous silica, MOF (metal organic structure), etc. An outer filtration membrane (UF), a reverse osmosis filtration membrane (RO)), a separation membrane capable of separation at a molecular level, or the like may be used.

B-5. Fifth modification:
In the above-described embodiment, a multi-layer base material having a plurality of layers having different pore diameters and materials in a region where the base material separation membrane is formed may be used. For example, a two-layer structure in which a porous intermediate layer having a pore diameter smaller than that of the base material 22 and larger than that of the separation membrane 24 is provided on the surface of the support channel 26 having the same shape as the base material 22 of the above-described embodiment. The substrate can be used. In this case, the separation membrane 24 may be formed on the surface of the intermediate layer. The intermediate layer may be formed of the same material as the support, or may be formed of a different material. Further, the intermediate layer may be formed of a material having the same pore diameter as that of the support and a material different from that of the support. Furthermore, the intermediate layer may be two or more layers, and a base material having three or more layers may be formed.

B-6. Sixth modification:
In the above embodiment, the first sealing layer 28 covers the first end surface 221 of the base material 22, but the entire first end surface 221 may not be covered by the first sealing layer 28. . The sealing layer 28 may be soaked into the pores so as to block the pores exposed to the first end surface 221 among the pores of the base material 22. In the vicinity of the first end surface 221 of the separation membrane 24, the first seal layer 28 formed in the vicinity of the first end surface 221 of the outer peripheral surface 223, the second end surface 222 of the base material 22, and the second of the separation membrane 24. The same applies to the second seal layer 29 formed in the vicinity of the end face 222 and in the vicinity of the second end face 222 of the outer peripheral surface 223. Even in this case, the liquid to be treated passes only through the base material 22 without passing through the separation membrane 24 and is mixed into the filtrate, or the filtrate that has passed through the separation membrane 24 passes through the base material 22. It can suppress that processing efficiency falls by mixing in a concentrate. However, with respect to the outer peripheral surface 223 of the base material 22, at least a region in contact with the O-

rings

37 and 38 is preferably covered with the seal layers 28 and 29. In this way, the sealing performance between the separation membrane structure 20 and the O-

rings

37 and 38 can be improved, and leakage of the liquid to be processed can be suppressed. Moreover, in the said embodiment, although the sealing layers 28 and 29 showed the example which has flowed into the pore, it does not need to flow into the pore. The seal layer should just be formed in the said 1st, 2nd end surface. Even if it does in this way, the effect similar to the said embodiment can be acquired.

B-7. Seventh modification:
In the above-described embodiment, an example in which the curvature radius Rs of the corners of the sealing layers 28 and 29 is larger than the curvature radius Rb of the corners of the base material 22 is shown. The portion may not have roundness, and the curvature radius Rb of the corner portion of the base material 22 may be equal to or larger than the curvature radius Rs of the corner portion of the seal layers 28 and 29. However, when the curvature radius Rs of the corners of the seal layers 28 and 29 is larger than the curvature radius Rb of the corners of the base material 22, the adhesion of the seal layers 28 and 29 and the flow of the fluid to be treated are improved. ,preferable.

DESCRIPTION OF SYMBOLS 20 ... Separation membrane structure 22 ... Base material 24 ... Separation membrane 26 ... Flow path 28 ... 1st sealing layer 29 ... 2nd sealing layer 30 ... Housing | casing 31 ... Inlet 32 ... Concentrate discharge port 33 ... 1st Filtrate port 34 ... Second filtrate port 35 ... Metal blocking member 36 ... Metal blocking member 37-40 ... O-ring 100 ... Separation membrane structure module 221 ... First end surface 222 ... Second end surface 223 ... peripheral surface

Claims

A base made of a porous inorganic material, comprising: a first end surface in the longitudinal direction; a second end surface; and a flow path through which the first end surface and the second end surface communicate with each other and a fluid to be treated flows. Material,
A separation membrane formed on the inner wall surface or the outer wall surface of the flow path;
A seal layer having high alkali resistance formed at least on the first and second end faces;
A separation membrane structure comprising:
In the separation membrane structure according to claim 1,
The sealing layer is a separation membrane structure having a surface roughness Ra of 0.5 μm or less after being immersed in a 4% by weight sodium hydroxide aqueous solution at 80 ° C. for 1000 hours.
The separation membrane structure according to claim 2,
The said sealing layer is a separation membrane structure whose ratio of the variation | change_quantity of the surface roughness Ra before and behind the said immersion with respect to the surface roughness Ra before the said immersion is less than 0.5.
In the separation membrane structure according to any one of claims 1 to 3,
The sealing layer has a separation membrane structure having a static friction coefficient μs of less than 0.5.
In the separation membrane structure according to any one of claims 1 to 4,
The sealing layer is a separation membrane structure formed of a fluorine-based resin.
In the separation membrane structure according to any one of claims 1 to 5,
The sealing layer is a separation membrane structure formed of tetrafluoroethylene or a copolymer fluororesin compound having tetrafluoroethylene as a basic molecular skeleton.
In the separation membrane structure according to any one of claims 1 to 6,
The sealing layer covers the first and second end surfaces of the base material, an outer peripheral surface near the first and second end surfaces, and the separation membrane near the first and second end surfaces,
The separation membrane structure, wherein the sealing layer formed on the outer peripheral surface and the separation membrane is formed continuously from the sealing layers formed on the first and second end surfaces.
The separation membrane structure according to claim 7,
Formed on the substrate corner formed by the first end surface and the second end surface of the substrate, the outer peripheral surface and the inner wall surface of the flow path, and the substrate corner The seal layer corner of the seal layer has a roundness, and the curvature radius Rs of the seal layer corner is larger than the curvature radius Rb of the substrate corner.
Separation membrane structure.
A separation membrane structure module comprising: the separation membrane structure according to any one of claims 1 to 8; and a housing for storing the separation membrane structure therein.
In the separation membrane structure module according to claim 9,
The separation membrane structure is
Through the sealing member made of an elastic material, the vicinity of the first and second end surfaces of the outer peripheral surface of the base material is supported and stored in the housing,
The sealing layer is
Covering at least the first and second end surfaces, the separation membrane in the vicinity of the first and second end surfaces, and the position of the outer peripheral surface from the first and second end surfaces to the position in contact with the seal member;
Separation membrane structure module.