JPH0291B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gasket for an electrodialysis tank suitable for use in clamping type electrodialysis, and a method for manufacturing the same. In particular, the present invention relates to a gasket for an electrodialysis tank that integrates a spacer in the channel portion, and a method for manufacturing the same. Conventional clamp-type electrodialysis cells, in which multiple cation exchange membranes and anion exchange membranes are arranged alternately between electrodes via gaskets and spacers, are generally used for electrolyte concentration, temperature removal, etc. It is used. When performing electrodialysis using this electrodialysis tank, the most difficult points are obtaining uniform distribution of the fluid to the dialysis chambers formed within the dialysis tank, and ensuring that the fluid is distributed within each dialysis chamber and outside of the dialysis tank. This is to prevent leaks. The critical current density and scale deposition in the dialysis tank are regulated by the worst room in the dialysis chamber, so uniform distribution of the liquid in the dialysis chamber is extremely important for efficient operation. Furthermore, leakage of liquid between the dialysis rooms and outside the room causes mixing and loss of dialysed fluid, rendering the dialysis process itself meaningless, and is also a very serious problem for the dialysis tank. For this reason, various proposals have been made for gaskets and their waterways, but none of them have fully achieved the above objectives, or
Alternatively, they lacked long-term durability, which is essential in the case of industrial equipment, and both were unsatisfactory. That is, the conventional Japanese Patent Publication No. 38-2983,
No. 50-10711 proposes a method of fitting a filler into the channel, but in both cases, the gap between the fitted member and the gasket expands as it is used, and the ion exchange membrane in this area becomes damaged. This is undesirable because it causes deformation damage, uneven liquid dispersion, and increased liquid leakage. Particularly in the case of the method of fitting members for a shore road, it is easy to cause powder loss and deformation after disassembly and reassembly several times, making it extremely inconvenient to use on an industrial scale. For this reason, it was considered to integrate the Shiodome parts with the gasket, but if they were bonded with adhesive, the adhesive part would easily peel off after several disassembly and reassembly, and the adhesive part would be hard, so it was difficult to disassemble and reassemble. The spacer deforms during handling, which tends to cause liquid leakage and non-uniform dispersion, making it difficult to use on an industrial scale. The present invention eliminates these conventional deficiencies and provides a gasket with an integrated channel spacer, which is easy to handle and suitable for use on an industrial scale, and a method for manufacturing the same. In the present invention, a gasket frame member made of a vulcanized rubber sheet is provided with a notch for the current-carrying part and including one or more communication holes, a cross section of the notch for the notch is coated with glue, and the gasket is inserted into the gasket frame member. Make sure that the width of the spacer spacer, which is narrower than the width of the notch, does not come into contact with the glue, and is 0.5 to 20 mm wider than the cross section of the notch.
It is inserted into the notch of the seaway part keeping a distance of 1.0 mm, and unvulcanized rubber is placed between the adhesive and the spacer and in a part including the periphery of the spacer. A fixing vulcanized rubber formed by vulcanizing this is arranged.
To provide a gasket for an electrodialysis tank, in which a gasket and a Shiomichi spacer are fixed and integrated using adhesive and vulcanized rubber for fixing, and a method for producing the same. More specifically, a gasket frame member made of a vulcanized rubber sheet is provided with a notch that is connected to a notch that corresponds to the current-carrying part during gasket formation and includes one or more communicating holes, and the cross section of this notch is filled later. A rubber adhesive, so-called co-glue, preferably having the same or similar composition as the unvulcanized rubber to be used is applied. Next, a spacer whose width is narrower than this notch is inserted into this notch so that it does not come into contact with the previously applied adhesive, and unvulcanized rubber is then filled into a part of this notch, and the gasket member is assembled. A gasket for an electrodialyzer and a method for manufacturing the same, characterized in that the gasket and Shiodomi spacer are integrated by vulcanization after being roughly adhered. The gasket frame member in the present invention is made of natural rubber, synthetic rubber such as chloroprene rubber, and a vulcanized rubber sheet made by adding these to each other or by adding other substances to them. is 0.2~2mm and JIS HS is 30°~
A hardness of 95° is preferred. The molding method is to form a sheet of vulcanized rubber using a calender roll or the like, then punch it out to make a gasket frame, or to make a band from the sheet of vulcanized rubber and butt the end faces of the vulcanized rubber to create a gasket frame. It is preferable that the gasket frame is formed by joining the gaskets by adhesive or other means. In other words, if the gasket frame is manufactured by pressure molding or injection molding using a mold, which has been widely used in the past, when a large number of gaskets are stacked together with an ion exchange membrane in a dialysis tank as a gasket, the mold itself will be damaged and the press Due to their tendency, the difference in thickness between each sheet adds up, causing liquid to leak from localized thin areas, which is undesirable. In the present invention, the Shiodomachi spacer that is inserted into the notch and integrated by vulcanizing unvulcanized rubber, and a part of which is used as a Shiodome, is preferably a mesh spacer that is conventionally generally used in Shiodome and dialysis rooms. . For example, a lattice shape, a honeycomb shape, a mikoshiro shape, etc. are preferred, and a diagonal mesh shape is particularly preferred. Preferably, the material is a synthetic resin such as polyvinyl chloride, saran, polyethylene, or polypropylene, and has an ASTM Shore D hardness of 50° to 110°. Furthermore, the shape of the net-like spacer to be inserted into the notch is preferably such that the spacer has a communicating hole notch in its shape. By adopting such a configuration, the area of integration with the gasket frame is increased, durability is increased, and the effect of preventing liquid leakage can also be enhanced. When fixing the spacer to the gasket frame member, preferably the distance between the gasket frame fixing surface and the spacer is 0.5 to 20 mm, so that the spacer does not touch the fixing surface of the gasket.
More preferably, it is desirable to insert a spacer into the gasket frame member notch at a distance of 1 to 10 mm. In other words, if unvulcanized rubber is filled and vulcanized and fixed while the spacer is in contact with the fixing surface of the gasket frame, the thickness of the vulcanized rubber will be poor, the spacer will be deformed during vulcanization, and the fixing force will be weak. For,
When a dialysis tank is assembled using such a gasket frame, leakage of the liquid and non-uniform distribution of the liquid may occur, and deformation such as spacers coming off may occur during several disassembly and reassembly, which is impractical. Also, if you create a gasket by leaving a gap of 20 mm or more between the fixed surface of the gasket frame and the spacer, filling it with unvulcanized rubber and vulcanizing it to make it stick, the unvulcanized rubber will move laterally during vulcanization. increases and spacer deformation occurs. Also, because the thickness accuracy of the unvulcanized rubber used for fixing is not very high, when many are stacked in a dialysis tank,
This is undesirable as it may cause liquid leakage. The spacer may be inserted into the notch of the gasket frame member and fixed after the vulcanized rubber sheet is formed into a gasket frame shape.For a gasket frame formed by joining the ends of a vulcanized rubber strip, The gasket may be formed by making a notch containing a communication hole in the band-like body, inserting a spacer and fixing it, and then joining it with another band-like body. The unvulcanized rubber used in the present invention includes natural rubber,
Synthetic rubber such as chloroprene, sealant such as thiocol, a mixture of these, or an unvulcanized rubber obtained by adding other substances to these is used. In this case, it is preferable to contain a rubber component contained in a vulcanized rubber sheet used as a gasket member. After adding an appropriate commonly used vulcanizing agent to this rubber, a cross section of the gasket member to which this rubber is bonded (glue is applied to the cross section)
This is filled into the corresponding gap between the spacer and the spacer, and after the unvulcanized rubber and the gasket frame member are roughly adhered to each other via the adhesive, the spacer is attached to the gasket by vulcanization. It is integrated with the frame member, thus producing a gasket frame. At this time, it is necessary to fill and vulcanize the unvulcanized rubber in such a way that an appropriately shaped channel is formed in the spacer portion. The form of unvulcanized rubber is either liquid or solid, and either can be used, but after adding a vulcanizing agent and, if necessary, a vulcanizing aid to solid unvulcanized rubber, a sheet is prepared. It is preferable to mold the material into a shape and then cut it into the appropriate shape before use.
When filling the mesh spacer and vulcanizing it, it is preferable to heat it if necessary, and it is also preferable to press it from above and below in a sandwich-like manner since this can make the thickness of the rubber being vulcanized uniform. The average thickness of the spacer to be inserted is - compared to the average thickness of the vulcanized rubber sheet used as a gasket member.
The range is preferably 8% to +15%, preferably -5 to +10%, and more preferably 0 to +10%. Further, after vulcanization molding of the unvulcanized rubber, the average thickness of this portion is -8% to +15%, preferably -5 to +10%, more preferably 0 to +15%, relative to the average thickness of the cross-cured rubber sheet as a gasket member. It is better to have a thickness of +10%. In other words, if the vulcanization molding part and spacer are thicker or thinner than the gasket member, fluid leakage will increase when constructing an electrodialysis tank, and a large amount of tightening force will be required to prevent fluid leakage, and the number of frames etc. will increase. In addition to increasing fatigue in the dialysis chamber, it also tends to cause distortion of the dialysis chamber and uneven distribution of the fluid. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 A vulcanized natural rubber sheet with a JIS HS hardness of 75° and an average thickness of 0.75 mm was prepared with a width of 35 m/m x a length of 693 m/m.
It was cut into strips measuring 72 m/m x 351 m/m thick at a number ratio of 1:1. Then, connect them with rubber adhesive at the positions indicated by the broken lines in Figure 1 to create an effective current-carrying area.
A picture frame-shaped gasket frame of 19.6 dm ² was manufactured. Next, the upper and lower wide strips have a diameter of 22m/m and a diameter of 39m.
Seven m/m holes were alternately drilled with equal center spacing. Furthermore, the hole with a diameter of 39 m/m was cut out to a width of 39 m/m in the direction of the current-carrying part. A hole with a semi-elliptical shape of width 37 m/m x length 25.5 m/m x radius 18.5 m/m and a diameter of 22 m/m centered at the center position of 18.5 m/m was drilled in this notch. 3 As shown in Figure 3-1, the thickness is 0.8 m/m, the mesh pitch is 3 m/m vertically and 3 m/m horizontally, and Shore D hardness is 100.
Polypropylene diagonal mesh spacers were inserted with a gap of 1 m/m on both sides. Then, after adding 1% of vulcanizing agent to unvulcanized natural rubber, it was heated to 0.8 at 60℃.
Formed into a sheet with a thickness of m/m, and an inner diameter of 29 m/m.
m, outer diameter 39m/m, depth 45m/m, width 5m/m,
It was cut into a horseshoe shape with a thickness of 0.8 m/m as shown in Figure 3-2. Next, after applying an adhesive (so-called co-glue) with exactly the same composition as this unvulcanized natural rubber to the cross section of the gasket notch that was previously prepared, this part and the unvulcanized natural rubber cut into a horseshoe shape are manually attached. Place it on the spacer while sticking it lightly with the
Heat press with a surface pressure of 5 kg/cm ² for 3 minutes at
This unvulcanized natural rubber was embedded in a spacer, molded and vulcanized, and integrated with a gasket frame to produce a gasket for an electrodialysis tank having seven channels with a liquid passage width of 26 m/m. In the completed gasket frame, the thickness of the part where the unvulcanized rubber is vulcanized is
It was 0.82m/m. Figure 2 shows the shape of the completed gasket frame. In Fig. 2, 1 is a gasket frame, 2 is a channel in which unvulcanized natural rubber is embedded in a spacer, vulcanized, and integrated with the gasket frame, 3 is a communication hole for the diluted liquid flow and concentrated liquid flow, and 4 is a The current-carrying part 5 indicates a diagonal mesh spacer of the same type as that used for the shore path part, which was cut and inserted so as to have a gap of 1 m/m vertically and horizontally to the current-carrying part 4. 150 gaskets made using the above method were
It has a hole inlet and 4 hole outlets for the dilution chamber, and is also 150 mm.
The sheet has a 4-hole inlet and 3-hole outlet for the concentration chamber, and is made of Asahi Kasei Aciprex K-101 (cation exchange membrane).
150 sheets and 150 sheets of A-101 (anion exchange membrane) were used, and these were assembled alternately with polypropylene diagonal mesh spacers for current-carrying parts with a thickness of 0.8 m/m, and after temporarily tightening with a fastening frame, a filter press was used. After attaching it to a type electrodialysis tank and tightening it with a hydraulic press, diluted seawater of 1200 ppm was flowed into the concentration chamber and dilution chamber at a linear velocity of 8 cm/sec, but leakage from the dialysis tank to the outside (hereinafter referred to as leak outside the tank) occurred. ), so the pressure of the hydraulic press was increased to reduce this leak outside the tank to zero, and the pressure was 1 kg/cm ² G per effective energized area. Then, after stopping the supply of diluted seawater to the concentration chamber and sufficiently draining the concentration chamber liquid, we measured the leakage of diluted seawater into the concentration chamber (hereinafter referred to as tank leakage) and found that it was 2c.c per minute per chamber. .It was hot. Furthermore, after flowing diluted seawater into the concentration chamber again,
Partial circulation desalination was performed at a temperature of 20 to 25°C, and the raw water concentration was 1200 ppm and the dilution outlet concentration was adjusted to 500 ppm.
The limiting current density at this time was 0.55 A/dm ² .
Furthermore, set the current density to 80% of this critical current density.
The operation was carried out for 10 days, and the average desalination capacity at this time was 3.5 m ³ /H. After this, I tried disassembling it, but there was no deformation of the gasket. The system was then reassembled, measured for leakage, operated for 10 days, and then disassembled, for a total of 30 days since installation. The observation results leaked for each 10-day period were as follows.

[Table] Example 2 A gasket frame with holes and notches was made from the same rubber sheet as in Example 1 by the same method. Then width 37m/m x length 25.5m/m x radius 18.5
The mesh pitch is a semi-elliptical shape with a diameter of 22 m/m and a center position of 18.5 m/m, with a diameter of 3 m/m x a width of 3 m/m, and a thickness of 0.75 m/m.
A polypropylene diagonal mesh spacer having a Shore D hardness of 100 degrees was integrated with a gasket frame in the same manner as in Example 1 to produce a gasket frame for electrodialysis. The thickness of the portion of the completed gasket frame where the unvulcanized rubber was vulcanized was 0.78 m/m. When the pressure at which leakage outside the tank becomes "0" was measured using the same method as in Example 1, the pressure at which leakage outside the tank became "0" was found to be 2
It was Kg/cm ² G. Furthermore, when leakage inside the tank was measured, it was found to be 5 c.c. per minute per chamber. Furthermore, when the limiting current density was measured under the same conditions as in Example 1, it was 0.53 A/dm ² . Furthermore, the desalination capacity was 3.3 m ³ /H when the current density was set to 80% of this limiting current density and the operation was carried out for 10 days. After this, disassembly, reassembly, and operation were repeated twice, and then the critical current density was measured. The results are as follows.

[Table] Comparative Example 1 A gasket frame with a notch was made in the same manner as in Example 1. This notch has a width of 39m/m x a length of 25.5m/m
A diagonal mesh spacer made of polypropylene with the same specifications as that used in Example 1 was used, which had a semi-elliptical shape with a radius of 19.5 m/m and a hole with a diameter of 22 m/m with the hole center at the center position of 19.5 m/m. I inserted it tightly. The unvulcanized natural rubber was then formed into a sheet in exactly the same manner as in Example 1, and further cut into a horseshoe shape with the same dimensions as in Example 1. Next, in exactly the same manner as in Example 1, the cross section of the gasket notch and the horseshoe-shaped unvulcanized natural rubber were adhered, and then hot pressing was carried out in the same manner as in Example 1 to integrate the shiodo and the gasket frame. 300 gaskets for an electrodialysis tank each having 7 channels with a liquid passage width of 26 m/m were manufactured. The average thickness of the vulcanized and fixed parts of these 300 gaskets was 0.89 m/m. Furthermore, 82 of them have spacers or vulcanized rubber burrs of unvulcanized natural rubber protruding from the surface of the so-called vulcanized fixing part, which is the part where the gasket's groove and gasket frame are integrated, and the thickness is 0.84 to 0.96. m/m thick,
In addition, in a part of the 177 gaskets, a part of the vulcanized bonded part was not fixed to the notch part of the gasket frame, so-called ``screen-like''. This gasket was assembled in the same manner as in Example 1, and leakage outside the tank was confirmed.
Even at Kg/cm ² G, it was not possible to stop leakage outside the tank. Comparative Example 2 Internal method as shown in Figure 3-2 described in Example 129
m/m, outer diameter 39m/m, depth 45m/m, width 5m/m
On top of unvulcanized natural rubber cut into a horseshoe shape with a thickness of 0.8 m/m, a polypropylene material with the same specifications, dimensions, and shape as shown in Figure 3-1 as used in Example 1 was placed. Diagonal mesh spacer diameter 22m/
Place the unvulcanized rubber cut into the horseshoe shape above so that the center of the hole m is aligned with the center of the bend,
A heat press was performed at 150°C for 3 minutes to embed unvulcanized natural rubber into the spacer, which was then molded and vulcanized to produce a shore path. The average thickness of the area where the unvulcanized natural rubber of the finished Shiodo was embedded in the spacer and vulcanized was 0.82 m/m. This was adhered using a rubber adhesive (Three Bond 1521) to the notched gasket frame prepared in the same manner as in Example 1 at the position indicated by the broken line in FIG. The gasket thus prepared was assembled into an electrodialysis tank together with an ion exchange membrane and a spacer in the same manner as in Example 1. In this case, the pressure per effective energized area at which leakage outside the tank becomes 0 is 3 Kg/cm ² , the leakage inside the tank at this time is 6 c.c./min/cell, and the critical current density is 0.53 A/dm ² It was hot. 80 of critical current density
% current density and desalination was carried out for 10 days, and the production capacity at this time was 3.3 m ³ /H. The disassembly, reassembly, and operation were repeated two more times, and the critical current density was measured after disassembly and reassembly. The results are as follows. In addition, the shore path that came off during disassembly and reassembly was reattached and used next time.
However, during the third disassembly, we reassembled the structure, excluding the removed shoreline, and measured leakage and critical current density.

【table】

[Table] Comparative Example 3 A picture frame-shaped gasket frame was made using the same rubber sheet, the same dimensions, and the same method as in Example 1, and then 7 holes with diameters of 22 m/m and 28 m/m were alternately formed in the upper and lower strips. The centers of the holes were evenly spaced. Furthermore, diameter 28
For the part where the hole of m/m was drilled, a notch with a width of 28 m/m was made in the direction of the current-carrying part. Next, the same polypropylene diagonal mesh spacer used as the Shiodome spacer in Example 2 was integrated with the current-carrying part and the Shiodome part notch, and a gap of 1 m/m on both the top, bottom, left and right sides of the gasket frame was made. It was cut so that it would hold. In addition, the spacer that enters this notch has a diameter of 22 m/
The hole was drilled so that the center of the 22m/m hole was on the same line as the center of the 22m/m hole in the gasket frame. Figure 4 shows the shape of the completed gasket and spacer. 6 in Figure 4
7 shows a gasket, 7 shows a path, and a spacer 8 integrated with a current-carrying part shows a communication hole for a diluted liquid flow and a concentrated liquid flow. The 300 gasket frames produced by the above method were assembled into 150 gasket frames for the dilution chamber and 150 for the concentration chamber in the same manner as in Example 1, and then attached to the dialysis machine in the same manner as in Example 1 to prevent leakage outside the tank. When we measured the pressure per effective current-carrying area that became "0", we found that it was 3Kg/
It was warm in ^cm2 . Furthermore, when leakage inside the tank was measured using a method similar to that described in Example 1,
It was 18 c.c. per minute per room. Next, the limiting current density was measured in the same manner as in Example 1.
The limiting current density was 0.48 A/dm ² , and the desalination capacity was 2.7 m ³ /H when the current density was set to 80% of the limiting current density. Comparative Example 4 An electric pipe having seven channels with a liquid passage width of 26 m/m was prepared in exactly the same manner as in Example 1 except that no glue was applied to the cross section of the gasket notch, and the channel and gasket were integrated. We produced 300 gaskets for dialysis tanks. The average thickness of the vulcanized and fixed portions of these 300 gaskets was 0.84 m/m. Moreover, someday
The thickness of the vulcanized and fixed part of the 25 gaskets is 0.9
m/m or more (+0.25 m/m relative to gasket thickness)
m), so the vulcanization press pressure was applied again in Example 1.
Pressure is twice as high as (10Kg/cm ² ) and seal the gasket.
300 pieces were made. The average thickness of the vulcanized and fixed portion of this gasket was 0.79 m/m. But within that
A part of the Shiodo spacer of 40 gaskets was bent and wrinkled. This gasket was assembled in the same manner as in Example 1, and the pressure of the hydraulic press that caused leakage outside the tank to be "0" was measured. It was 3 kg/cm ² G per effective current-carrying area, which was three times the pressure in Example 1. I needed it. Furthermore, when we measured the leakage inside the tank, we found that the leakage rate was 15% per minute per room.
cc, which was 7.5 times that of Example 1. After disassembling the membrane and observing the ion exchange membrane and gasket, it was discovered that a pinhole, a fatal defect, had occurred at the part of the ion exchange membrane where the creases of the Shiodo spacer hit.

[Brief explanation of drawings]

Figure 1 shows a frame-shaped gasket frame made by gluing together two types of strips obtained by cutting a sheet along the broken lines, and Figure 2 shows a diagonal net-shaped spacer in the shiodo area embedded in unvulcanized natural rubber and heated. This shows a gasket that has been vulcanized and molded using a press and is integrated with the gasket frame. 1... Gasket frame, 2... Shiodo, which is made by embedding unvulcanized natural rubber in a spacer and vulcanizing it to integrate with the gasket frame, 3... Communication hole for diluted liquid flow and concentrated liquid flow, 4... Current-carrying part, 5... Current-carrying part diagonal mesh spacer. Figure 3 shows Shiodo, which is made by vulcanizing and molding unvulcanized natural rubber and a diagonal mesh spacer using a hot press, and the unvulcanized natural rubber and diagonal used in the process of making the gasket obtained by gluing the gasket frame. This figure shows the shape of a single row mesh spacer. Figure 3 3-1
... Oblique mesh spacer, Fig. 3 3-2 ... Unvulcanized natural rubber. FIG. 4 shows a gasket with a notch in which the same diagonal mesh spacer is inserted in both the passageway section and the current carrying section. 6... Gasket, 7... Diagonal mesh spacer for the current-carrying part and the tideway part, 8... Communication hole for the diluted liquid flow and the concentrated liquid flow.

Claims (1)

[Scope of Claims] 1. A gasket frame member made of a vulcanized rubber sheet is provided with a notch in the current-carrying part and including one or more communication holes, and a glue is applied to the cross section of the cutout in the notch. Insert the Shiodome spacer, whose insertion width is narrower than this Shiodome notch, into the Shiodome notch so that it does not come into contact with the glue and maintain a gap of 0.5 to 20 mm from the cutout cross section of the Shiodome notch. A vulcanized rubber for adhesion, which is formed by placing unvulcanized rubber in the gap between the adhesive and the Shiodo spacer and in a part including the periphery of the Shiodo spacer, is then vulcanized. A gasket for an electrodialysis tank, characterized in that the gasket and the Shiodome spacer are fixed and integrated using adhesive and vulcanized rubber for fixing. 2. A gasket frame member made of a vulcanized rubber sheet is provided with a notch in the current-carrying part that is connected to the notch in the current-carrying part and includes one or more communication holes, and a glue is applied to the cross section of the notch in the notch, and the width of the insertion part is adjusted to the width of this part. Insert the Shiodome Spacer, which is narrower than the Shiodome Notch, into the Shiodome Notch so that it does not come in contact with the glue and maintain a gap of 0.5 to 20 mm from the cutout cross section of the Shiodome Notch, and then insert the Shiodome Spacer, which is narrower than the Shiodome Spacer, into the Shiodome Notch so that it does not touch the glue and keep a gap of 0.5 to 20 mm from the cutout cross section of the Shiodome Notch. A gasket and a Shiodo spacer are characterized in that unvulcanized rubber is placed in a part including the gap and the periphery of the Shiodo spacer, and then this is vulcanized to form a vulcanized rubber for adhesion. A method for manufacturing a gasket for an electrodialysis tank that is fixed and integrated using adhesive and vulcanized rubber for fixing.