KR860001804B1 - Gasket for electrodialysis - Google Patents

Abstract

Gasket to be used in an electrodialysis cell comprises a retriculated spacer and a gasket frame united with the spacer. Vulcanised rubber is partially packed in the space, and the spacer has a channel- forming construction. The gasket frame is made of a vulcanised rubber sheet. The gasket is useful in an electrodialysis cell for concentration or desalination of an electrolyte. Owing to the unification of the vulcanised rubber part paced in the spacer to the gasket frame, a proper channel spacer can be easily formed. The unification is also effective in the uniform dispersion of the electrolyte, reducing a leak current and leakage of the electrolyte.

Description

Electric Dialysis Gasket

1 is a vertical side view of the electrodialysis tank in which the gasket according to the present invention is partially cut and shown schematically.

FIG. 2 is a diagram showing a configuration arrangement of an anion exchange membrane, a cation exchange membrane, and a spacer provided with a stack of the electrodialysis tank of FIG. 1 to explain the principle of electrodialysis and the function of the gasket.

3 is a plan view of a gasket frame used for one type of gasket according to the present invention.

4 is a plan view of the gasket frame shown in FIG. 3 with a number of cuts and conduit forming bores formed therein.

FIG. 5 is a plan view of a spacer such as a net having a conduit-shaped hole to be inserted into the gasket frame of FIG.

FIG. 6 is a plan view of the unvulcanized rubber made to be installed on the peripheral portion of the spacer of FIG.

FIG. 7 is a plan view of a gasket formed by forming a gasket frame of FIG. 4, a frame of FIG. 5, and vulcanized rubber formed by vulcanization of unvulcanized rubber of FIG.

FIG. 8 is a sandwich of the entire circumferential portion of the same mesh spacer as the spacer of FIG. 5 with unvulcanized rubber having a shape, and the portion is made to be inserted into the cut portion of the same frame as shown in FIG. A cross sectional view of a portion of the reticulated spacer viewed from the opening of this cut.

9 is a plan view of an unvulcanized rubber having another shape to be installed at the periphery of the mesh auxiliary spacer inserted in the cutting portion as shown in FIG.

10 is a plan view of another gasket according to the present invention using unvulcanized rubber having the shape of FIG.

11 is a plan view of another form of auxiliary mesh spacers, with the two-sided edges respectively inserted in unvulcanized rubber strips.

12 is a plan view of another embodiment of a gasket according to the present invention using the auxiliary mesh spacer of FIG.

FIG. 13 (a) is a view showing another form of the auxiliary mesh spacer having the plate forming hole. FIG.

FIG. 13 (b) shows another form of unvulcanized rubber having a shape provided in the periphery of the auxiliary mesh spacer of FIG. 13 (a) inserted in the cutout portion as shown in FIG.

FIG. 14 is a plan view of another embodiment of a gasket according to the present invention using the auxiliary mesh spacer of FIG. 13 (a) and unvulcanized rubber having the shape of FIG. 13 (b).

FIG. 15 is a plan view of another form of unvulcanized rubber having a shape to be installed at a peripheral portion 1 of the auxiliary reticulated spacer inserted into the cut portion as shown in FIG.

FIG. 16 shows another form of a gasket according to the invention in which unvulcanized rubber having the shape of FIG. 15 is used.

17 is a plan view of a comparative example of a gasket in which a gap is left between the inner wall of the cut and the periphery of the auxiliary reticulated portion.

18 shows a sandwich between a pair of gasket frames having the same shape as the mesh spacers and each having a smaller central opening than the mesh spacers so that the peripheral edges of the mesh spacers surround the central opening. FIG. 4 shows another comparative example of a gasket for overlapping a frame along an edge portion. FIG.

19 and 20 show another comparative example of a gasket having an insufficient length of vulcanized rubber connecting the periphery of the auxiliary mesh spacer and the inner wall of the cut portion of the frame, respectively.

* Explanation of symbols for main parts of the drawings

1: cathode frame 7: anion exchange membrane

2: feeding frame 8: cation exchange membrane

3: tightening frame 9: gasket

4: stack 11, 11 ': spacer

5: anodized frame 12: gasket frame

13: conduit forming bore 14: central portion

6: press body

The present invention relates to a gasket for use in an electrodialysis tank which can be advantageously used in an electrodialysis tank for a filter press, in particular, which is a mesh made of vulcanized rubber and a mesh opening which functions as a passage through the central opening. It consists of a frame with cuts with spacers, the frame and the meshed spacers making a consistent connection by vulcanizing rubber between them, so that the liquid has a central opening without involving liquid leakage in or outside the cell dialysis tank. The present invention relates to a gasket for an electrodialysis tank not only to be supplied and distributed to the electrodialysis tank but also to be disassembled and reassembled in a short time.

At present, a filter press-type electrodialysis tank apparatus (hereinafter simply referred to as electrodialysis tank) in which a plurality of cation exchange membranes and anion exchange membranes are alternately arranged through an insertion gasket provided with spacers tightened between a pair of electrodes is concentrated. It is widely used for salt removal and other purposes. In carrying out electrodialysis in this type of electrodialysis tank, the most serious problem to be taken into account is to ensure uniform liquid distribution between the dialysis chamber formed between the anion exchange membrane and the cation exchange membrane of the electrodialysis vessel and from within or from the electrodialysis vessel. To prevent the leakage of liquid. The uniform distribution of the liquid between the dialysis chambers is very important for the efficient operation of the electrodialysis tank, since the limit current density and scale precipitation are determined by the worst-case dialysis chamber.

Moreover, leakage of liquid in or from the electrolyzer causes contamination or loss of the electrodialysis fluid, making the electrodialysis itself meaningless. Therefore, such leakage is an extremely serious problem in electrodialysis.

In order to solve this problem, several methods have been proposed for the gasket structure. In particular, a liquid passage portion which functions to connect the dialysis chamber and the conduit to introduce the electrodialysis liquid into the dialysis chamber and discharge the electrodialysis liquid from the dialysis chamber. (liquid passage portions). However, any gasket thus far is still insufficient to solve the problem because of poor durability, which is an essential requirement of commercial electrodialysis baths.

For example, in the prior art, that is, U.S. Patent No. 3,933,617 proposes a gasket structure consisting of an insert formed separately from the body of the frame, the portion of the frame defining a passageway connecting the conduit to the central opening of the frame. . However, in this gasket, the gap between the insert and the frame increases with the passage of operating time. Increasing this gap will result in deformation or damage of the ion exchange membrane in contact with the passage, resulting in non-uniform distribution of the liquid and poorly increasing liquid leakage. Moreover, during the disassembly and assembly of the electrodialysis tank several times, the members constituting the electrodialysis tank may be lost, as well as it may cause deformation or leakage. Therefore, gaskets excluded from this patent are encountered in various difficulties in practical use.

Since the mesh spacer used in the electrodialysis tank is easily contaminated by the contaminants contained in the electrolytic solution supplied to the electrodialysis tank, it is usually necessary to disassemble and clean the device several times a year. Therefore, in order to operate the electrodialysis tank safely and stably, the disassembly, cleaning and reassembly of the apparatus should be carried out simply and reliably within a short period of time, which makes a great contribution to the operation efficiency of the electrodialysis tank. In this regard, there have been some exclusions consisting of frames and spacers in which gaskets are formed integrally with each other. However, other fatal shortcomings have been addressed with these.

For example, in Japanese Utility Model Registration No. 1714/1979, a pair of frames, each having a central opening, each of which is press-rolled a rubber raw material, each of which is centered between the frames. To describe a gasket structure produced by a method consisting of inserting a large spacer of a size larger than the area of an opening, and forming the pair of frames and the spacer sandwiched therebetween by adhesive or bonding into a single gasket. have. In this known method, the final step for forming a single gasket structure is usually carried out utilizing pressing by molding. However, such a gasket structure is inevitable in thickness nonuniformity, because the overall shape of the gasket is directly affected by the nonuniformity of the molding itself or the local difference in pressure exerted in the pressing operation. When a large number of such gasket structures and ion exchange membranes are alternately arranged and tightened in an electrodialysis bath, this non-uniform thickness builds up, forming a locally appearing very thin area that is likely to leak liquid. This problem is more apparent in larger devices.

The inventors have made extensive and intensive studies to eliminate the above-mentioned disadvantages and provide an electrodialysis gasket that can be suitably used on an excellent and commercial scale in terms of maintenance and operation. As a result, a gasket structure effective for this purpose has been invented, which is composed of a frame made of vulcanized rubber and a frame having cutout portions having a central opening and a reticulated spacer each functioning as a passage through the central opening. The frame and the mesh spacers make a consistent connection by the vulcanized rubber between them. Accordingly, the present invention has been made.

Accordingly, the object of the present invention is not only to supply and dispense the liquid to the central opening without involving leakage of the liquid in or from the electrodialysis tank, but also to disassemble and reassemble the electrodialysis tank in a short time. To provide an electrodialysis gasket. Another object of the present invention is to provide a gasket having the above-described characteristics, but which can be produced in a simple and inexpensive structure.

In essence, according to the present invention there is provided an electrodialysis bath gasket consisting of a plurality of alternating cation exchange membranes and anion exchange membranes and a gasket sandwiched therebetween, the gaskets being vulcanized rubber and facing first, first, It consists of a frame having a central opening defined by the third and fourth sides facing the two sides.

The central opening is made to receive a meshed main spacer therein, and a conduit forming bore is formed in the opposing first, second and opposing third and fourth sides of the frame to form a conduit of an adjacent frame. It is made to communicate directly with the forming hole.

Cutting portions are formed on opposite first, second and opposite third and fourth sides of the frame, each of which is independently connected to at least one conduit forming bore of the frame at least. It has one conduit hole, and the cut portion has both base ends, each defining an opening that opens to the center opening of the frame.

The cuts each have a mesh auxiliary spacer that forms a passage therein that leads to the central opening. This reticulated spacer has at least two sides, the sides of which are opposed to the inner wall of each cut through at least the gaps left at the sites of both sides, and at least the aforementioned gaps are reticulated at the sites corresponding to these gaps. Filled with vulcanized rubber connecting the at least both sides of the auxiliary spacer to the inner wall of each cut, wherein portions corresponding to the minimum portion of the gap extend inwardly from both base ends defining the openings of the respective cut. It has both base end portions, each of which is about 5% each based on the total length of the auxiliary reticulated spacers facing the inner wall of the cut portion, with portions corresponding to at least a portion of the gap. One or more portions interposed at each inner end of the base end portion, The intervening portions are continuous or discontinuous with respect to the base end portion extending inwardly from the base end independently of each other, while the intervening portions each have an auxiliary net spacer (opposed to the inner wall of the cut portion 12a). The absence of one or more unconnected sites extending continuously 30% or more based on the total length of the site of 17) is intended to form a single connection between the frame and the auxiliary reticulated spacer.

Referring to FIG. 1, number 1 designates a cathode frame containing a cathode (not shown) and number 5 designates a cathode (not shown) anode frame. There are a number of stacks 4 between the anode and cathode frames, each of which is tightened by a pair of tightening frames 3, 3 interposed between the feeding frames 2, 2. Although a number of stacks are usually integrated into one electrodialysis tank from a practical point of view, one stack is used in the embodiments of the present invention described below. The stack disposed between the cathode frame 1 and the anode frame 5 via each paired fastening frame 3, 3 and feeding frame 2, 2 is respectively a cathode frame 1 and an anodized. It is clamped by a pair of press members 6 and 6 located at the outer end of the wood frame 5.

Referring to FIG. 2, the stack 4 includes a gasket (or gaskets) each provided with a plurality of alternating anion exchange membranes 7 and 7, a cation exchange membrane 8, and spacers 11 and 11 'interposed therebetween. 9,10). As partly shown in FIG. 2, the stack 4 consists of a plurality of alternating dialysis and concentrated dialysis chambers separated by alternating anion exchange membranes 7 and cation exchange membranes 8. Usually, hundreds of dialysis chambers are formed in one stack.

Between each two adjacent membranes (i.e., anion exchange membrane and cation exchange membrane), a gasket having an opening in which a spacer is provided is disposed.

The liquid to be electrodialyzed is supplied to the dialysis chamber of the stack through a conduit leading to an inlet formed in the feeding frame 2, and the electrodialyzed liquid is discharged from an outlet formed in the rapid frame 2 through another conduit.

3 to 7, one embodiment of the present invention is shown.

Referring to FIG. 3, there is a gasket frame made of four strips cut from a vulcanized rubber sheet, with two relatively wide strips forming the first and second sides facing each other and two relatively narrow strips. Comprising the third and fourth sides of the frame, the four strips are joined to a portion indicated by dashed lines with an adhesive or the like.

4 shows a plurality of cuts with a respective base end defining an opening that is directly open to a central opening 12 b and a plurality of conduit forming bores 13 that communicate directly with the conduit forming holes of adjacent frames. region (12 a) that shows the gasket frame 12 is formed in the first and second sides of the frame.

FIG. 5 is a plan view of the reticulated spacer made to be inserted into the gasket frame shown in FIG. The plurality of portions 15 constitute an auxiliary mesh spacer to be inserted into the cut portion 12 a shown in FIG.

The center portion 14 constitutes a main mesh spacer to be inserted into the center opening 12 b of the frame shown in FIG.

The plurality of portions 15 constituting the auxiliary mesh spacers each have a conduiting aperture 16 formed therein, which is in direct correspondence with the conduiting bore of the adjacent frame. The auxiliary reticulated spacers each form a passage through the central opening 12 b .

The gasket frame 12, the mesh spacers constituting the central portion 14, and the plurality of portions 15 have a mesh spacer including a central opening 12 b and a plurality of cut portions 12 a therein. When inserted inside the frame, it has such a dimensional relationship that leaves a gap between the entire periphery of the mesh spacer and the entire inner wall of the gasket frame. FIG. 6 is a molded margarulum rubber that is installed at the edge of the mesh spacer of FIG. 5 to fill the aforementioned gap, which connects the inner wall of the frame with the peripheral wall of the main mesh spacer. Molded unvulcanized rubber was made by punching the unvulcanized rubber sheet with such a shape that its outer wall coincides with the inner wall of the gasket frame of FIG. .

FIG. 7 shows a gasket structure in which the spacer of FIG. 5 is connected to the gasket frame of FIG. 4 via a vulcanized rubber medium formed by vulcanization of the unvulcanized rubber of FIG. In FIG. 7, number 17 refers to an auxiliary reticulated portion that forms a passageway to the central portion 14 of the cut portion 12, wherein the openings 19 are both base ends 18, 18 of the cut portion. It is limited to.

FIG. 8 is a schematic cross sectional side view of the same reticulated spacer as shown in FIG. 5, but a sandwich of unvulcanized rubber with its entire periphery formed therein, the site being of the same frame as shown in FIG. It was made to be able to be inserted into the cut, which is taken in the opening of the cut. In FIG. 8, number 21 refers to a pair of molded unvulcanized rubber and number 22 refers to a reticulated spacer.

9 to 10 show another embodiment of the present invention, in which FIG. 9 is another form to be installed in the peripheral portion of the auxiliary mesh spacer 24 inserted in the cutting portion as shown in FIG. Is a plan view of molded unvulcanized rubber. FIG. 10 shows a gasket in which the mesh spacer 24 inserted into the frame cutting portion is firmly connected to the frame 23 in a single form through the medium of the vulcanized rubber 24 a formed by vulcanization of the molded unvulcanized rubber of FIG. The structure is shown. In FIG. 10, number 25 a refers to a conduit forming bore and number 25 b refers to a conduit forming hole.

11 to 12 show another embodiment of the present invention, wherein an auxiliary mesh spacer having no conduit forming holes is inserted in the cutout of the gasket frame. FIG. 11 is a plan view of the auxiliary mesh spacer 27, the edges of both sides of which are sandwiched by unvulcanized rubber strips 27 respectively attached thereto. Both free sides of the attached unvulcanized rubber strips are made so that the auxiliary web spacers to which the unvulcanized rubber strips are attached can face and come into contact with the inner wall of the cut section, respectively, when inserted into the cut section of the gasket frame.

In FIG. 12, another gasket structure of the present invention is shown. Here, the auxiliary mesh spacer shown in FIG. 11 is inserted into the cut portion together with the rubber strip 26 attached thereto, and then thermocompressed to form an auxiliary mesh. An auxiliary reticulated spacer inserted into the cut at each site spaced apart from the cut, while the spacer is connected to the inner wall of the cut through a medium of vulcanized rubber formed by vulcanization of the unvulcanized rubber strip 26. A space 30 b is defined, which is defined by each non-tangential short side and each inner wall of the cut portion. In a gasket structure as shown in Figure 12, the above-described vulcanized rubber are formed with the frame (28 performs the function of connecting the both sides and the inner wall of each cut portion of each auxiliary net-like spacer, the conduit forming the bore (30 a) ) And a single net spacer.

The gap 30 b constitutes a conduit forming hole in the cut portion. The central opening 31 of the frame 28 has a main mesh spacer 32 made separately from the auxiliary mesh spacer forming a passage 29 leading to the central opening 31 therein.

In the embodiment of Figs. 11 to 12, the closed end sides of each cut-out portion are not singly connected with the auxiliary mesh spacer. However, in the modified embodiment (not shown), another type of auxiliary reticulated spacer was used, which had both edge faces fitted to the unvulcanized rubber strip and, as shown in FIG. A vulcanized rubber having at least one recess and vulcanized by unvulcanized rubber along the entire length of the closed end edge of the frame, except at least one recess. It is firmly connected to the inner wall of the cut part. In this case, the at least one recess, which forms at least one conduit-forming hole at the cut, was left open.

13 (a), 13 (b) and 14, another embodiment of the present invention is shown. FIG. 13 (a) is a plan view of the auxiliary mesh spacer having a hole therein, and FIG. 13 (b) is a peripheral portion of the auxiliary mesh spacer 34 inserted at the cutting portion as shown in FIG. It is a top view of the molded unvulcanized rubber to be installed.

FIG. 14 shows that the reticulated spacer inserted into the cutout portion of the frame is rigidly formed in a single form with the frame 33 through the medium of the vulcanized rubber 34 a formed by vulcanization of the molded unvulcanized rubber of FIG. 13 (b). Is connected. In FIG. 14, number 35 a refers to the conduit forming door and number 35b refers to the conduit forming hole. The opening 36 in the center of the frame 33 has a main mesh spacer 37 made separately from the auxiliary mesh spacer forming a passage therein to the opening 36.

15 to 16, another embodiment of the present invention is shown, wherein an auxiliary mesh spacer inserted in each of the cutting portions of the frame is disposed between the auxiliary mesh spacing and the inner wall of the open cutting portion at its periphery. It is connected to the inner wall of the frame singly, leaving part of the gap formed. FIG. 15 shows molded unvulcanized rubber to be used in this embodiment.

FIG. 16 shows the following gasket structure, that is, the gasket frame having the bore 41a and the auxiliary net having the holes 41b through the vulcanized rubber 40 formed by vulcanizing each of the molded unvulcanized rubbers of FIG. It is connected to the type spacer. The central opening of the frame allowed it to carry a net-shaped spacer (not shown) therein.

17 through 20 illustrate comparative examples of various different gasket structures.

FIG. 17 shows a gasket in which a mesh spacer having an auxiliary space portion 42 a and a main spacer portion 43 is inserted into the gasket frame 42 without any connection between the mesh spacer and the frame. In FIG. 17, number 44 a refers to the conduit bore and number 44 b refers to the conduit hole.

FIG. 18 is another comparative embodiment of the gasket structure, wherein the mesh spacers are fixedly sandwiched between a pair of gasket frames having the same shape as each other and each having a smaller central opening than the mesh spacers. The peripheral edge of the mesh spacer overlaps the frame slightly along the respective edge portion surrounding the central opening.

Number 48 refers to the main reticulated spacer site corresponding to the central opening 47 of the frame, and number 48 a refers to the subweb shaped spacer site forming a passageway to the main web shaped spacer site.

Numerals 46 a and 46 b refer to conduit forming bores and conduiting holes, respectively.

19 and 20 are additional comparative examples of the gasket structure, respectively, where the length of the vulcanized rubber connecting the periphery of the auxiliary reticulated spacer and the inner wall of the cut portion of the frame is insufficient. In FIG. 19, the frame 49 has cut portions each having an auxiliary mesh spacer 50 inserted therein. The auxiliary mesh spacer only has its base ends connected to the inner wall of the cut portion. Numerals 52 a and 52 b refer to conduit forming bores and conduit forming holes, respectively. The frame 49 has a central opening made therein to accommodate the main spacer (not shown). In FIG. 20, the frame 53 has a cut portion into which the auxiliary mesh spacers 54 are inserted, respectively. The auxiliary reticulated spacers only have two sides connected to the inner wall of the cut site at their respective intermediate portions 55. Numerals 56 a and 56 b refer to conduit-forming bores and recessed holes, respectively.

Since none of the gasket comparative examples shown in FIGS. 17, 18, 19, and 20 have a single seam (FIG. 17), an insufficient number of single seams between the inner wall of the cut portion of the gasket frame and the auxiliary web spacer Because of their uneven thickness because of their length (19, 20 degrees) or by the presence of overlapping regions (18), they work unsatisfactorily when integrated into an electrodialysis bath.

The present invention will be described in more detail. In the present invention, the gasket frame is formed of a vulcanized rubber sheet that has already been made to have a uniform thickness by a press roller. A frame having a central opening defined by opposing first, second and third and fourth sides of the frame is made by directly punching the vulcanized rubber sheet. The frame may also consist of four strips cut from the vulcanized rubber plate as already described in connection with FIG. The central opening of the frame has a main meshed spacer therein or is adapted to receive it.

To make the vulcanized rubber plate, a synthetic rubber such as natural rubber, chloroprene rubber, or a mixture of suitable additives is mixed with the vulcanizing agent, and the calender is molded and vulcanized with a calender or extruder so that the thickness of the vulcanized rubber plate is 0.2 mm to 2 mm. . The vulcanized rubber sheet is advantageously of strength of 30 ° to 95 ° HS as measured according to the method specified in Japanese Industrial Standard 6301-1975.

The frame has conduit forming bores formed on either or both of the opposing first, second and / or opposing third and fourth sides. These bores are made in direct communication with the conduiting holes of adjacent frames. The frame also has cutouts formed on either or both of the opposing first, second and third and fourth sides, each of which is independently at least one of the adjacent frames in a directly corresponding relationship. It has at least one conduit forming hole in communication with two conduit forming bores. The cuts each have both base ends that define an opening that opens to the central opening of the frame. The cut sites each have an auxiliary reticulated spacer that forms a passage therein to the central opening.

The shape of the cut site is not critical and is determined by the shape of the auxiliary reticulated spacer to be inserted therein. For example, the cut portion may have a rectangular shape, a rounded rectangle of the nose holder, a semicircle, a semi-ellipse, and a trapezoidal or hood shape curved at both sides of the trapezoid.

On the other hand, the bore can take any shape, such as a circle, square, rectangle, ellipse, or the like.

The hole may also take any shape, a detailed description thereof will be described later. The main reticulated spacer and the auxiliary reticulated spacer may take any net pattern, but preferentially an inclined lattice pattern mesh having a pitch of 1.3 mm to 6.0 mm in one direction and a pitch of 1.3 mm to 6.0 mm in the direction crossing it. Has) As a raw material for the main and auxiliary reticulated spacers, thermoplastic resins such as polyethylene or polypropylene may be mentioned. It is advantageous for the raw material to have an ASTM shore D strength of 50 ° to 110 ° at the operating temperature of the electrodialysis bath. If a mesh spacer made of a raw material with a Show D strength of less than 50 ° is used, it may disadvantageously cause deformation of the ion exchange membrane sandwiched between gaskets having this mesh spacer.

On the other hand, when a mesh spacer made of a raw material having a show D hardness of 110 ° or more is used, small holes (pinhol) tend to be easily formed in the ion exchange membrane. The auxiliary mesh spacers to be inserted into each of the cutout portions of the main mesh spacer frame to be inserted into the central opening of the frame may be molded integrally with each other or independently of each other.

As mentioned above, the cuts of the frame each independently have at least one hole therein. In order that each cut can independently have at least one hole in it, it can take two different forms.

Illustratively, one type is to independently insert an auxiliary web spacer having at least one hole in the cutting site, and in another form, an auxiliary web spacer without any conduit forming holes is cut. It has two sides opposite to the inner wall of the site, while leaving a space defined by the inner wall of the cutting site, and the non-facing side of the auxiliary web spacer at each cutting site at a location spaced from the opening of the cutting site. This leaves the space to form a conduit forming hole at each cut. At least the gap is filled with vulcanized rubber, which vulcanized rubber connects at least the two sides of the auxiliary web-shaped spacer and the inner wall of the respective cut in at least the gap and at least the gap. The area includes both base end portions each extending inwardly from both base ends defining the openings of the cut portions, each about 5% of the length of the entire portion of the auxiliary reticulated spacer facing the inner wall of the cut portion. to be.

And at least a portion corresponding to the gap portion includes one or more portions interposed at respective inner ends of the two base end portions, the intervening portions each extending inwardly from both base ends. There is no one or more unconnected sites that are continuous or discontinuous independently of each other, while extending continuously 30% or more with respect to the total site length of the auxiliary reticulated spacer opposite the inner wall of each cut. do.

As evident from the above description, both inwardly extending from both base ends defining an opening of the cut portion over a length of about 5 percent of the total length of the auxiliary reticulated spacer facing the inner wall of the cut portion, respectively. At the base end site and at one or more sites interposed at each inner end of the base end site, there must be a gap between both sides of the auxiliary mesh spacer and the inner wall of the cutout of the frame.

The gap between the above-described base end portions of both base portions is filled with vulcanized rubber that connects both sides of the auxiliary web-shaped spacer and the inner wall of the cut portion at portions corresponding to the upper both base end portions.

Vulcanized rubber that connects the inner wall of the cut portion and the peripheral portion of the auxiliary mesh-shaped spacer at the portion corresponding to the minimum portion of the gap or the portion interposed at each inner end of both base end portions. Filled with. The portion or each portion interposed at each inner end of both base end portions respectively extends inwardly from both base ends and is based on the total length of the auxiliary reticulated spacer portion facing the inner wall of each cut portion. It is continuous or discontinuous with respect to the base end portion without leaving unconnected portions that each extend continuously over 30 percent in length. The gaps filled with vulcanized rubber and some gaps not filled are 0.5-20 mm wide, preferentially 1-10 mm.

At least a portion of the above-mentioned gaps may be unvulcanized rubber used to fill any synthetic rubber, such as natural rubber or chloroprene rubber, silicone rubber or thiocol (trade name of polysulfide type manufactured and marketed by Tiocol Chemical Co., Ltd., USA). have. These may be used alone or in combination. It is preferable to use the same type of unvulcanized rubber as the vulcanized rubber sheet from which the gasket frame is made. Furthermore, unvulcanized rubber may be added with additives such as carbon, metal oxide and the like.

Unvulcanized rubber may be solid or liquid. In practical terms, however, it is better to use solid unvulcanized rubber. The vulcanizing agent is added to the solid unvulcanized rubber together with an optional selected vulcanizing agent, and the resulting mixture is formed into a sheet, for example depending on the shape of the cut and the shape of the auxiliary reticulated spacer to be inserted. It cuts into the shape as shown in FIG. 9, FIG. 13 (b), or FIG.

Various methods can be used to produce the gasket of the present invention. For example, one method consists of: Insert the sub mesh spacers into the respective cut-outs of the frame placed on the support, and form at the outer side of the sub mesh spacers to leave a gap between the inner wall of the cut portion and the sub mesh spacers and cover the minimum part of the gap. Place the unvulcanized rubber. Thus, the minimum portion of the inner periphery of the unvulcanized rubber overlaps the edge of the corresponding auxiliary mesh spacer and the minimum portion of the outer periphery of the unvulcanized rubber is in contact with the inner wall of the cut portion. It is then heat pressed to vulcanize the unvulcanized rubber and eventually form a single connection between the auxiliary mesh spacer and the frame. Another method is constructed as follows.

The molded unvulcanized rubber is attached to the outside of the auxiliary mesh spacer to insert the auxiliary mesh spacer having the molded unvulcanized rubber portion into each cut portion of the frame placed on the support. Thus, the outer periphery of the unvulcanized rubber is brought into contact with the inner wall of the cut by using an adhesive, and then heated and pressed to vulcanize the unvulcanized rubber, thereby forming a single bond between the auxiliary mesh spacer and the frame.

Alternatively, an auxiliary reticulated spacer is inserted at each cut of the frame placed on the support, leaving gaps between the perimeter of the auxiliary web spacer and at least the inner wall of each cut at at least the periphery, and the liquid unvulcanized rubber is separated. Is applied to cover a minimum portion of the auxiliary mesh spacer, and the inner wall of each cut portion is connected to each other, and then the liquid unvulcanized rubber is heated pressed to cause vulcanization of the vulcanized rubber. A method of forming a single connection between frames can be used.

When the auxiliary reticulated spacer has at least two conduit holes in it, unvulcanized rubber may additionally be applied to the auxiliary reticulated spacer at site locations between mutually adjacent conduit forming holes for spacer reinforcement purposes. The additional vulcanization of the unvulcanized rubber can take place simultaneously with the vulcanization of the unvulcanized rubber applied to the minimum portion of the periphery of the auxiliary mesh spacer. In this case, the area to which the additional unvulcanized rubber is applied is not important, but is usually not more than 30% of the width of the auxiliary web spacer except for the portions of the at least two conduit-forming holes.

As mentioned above, the main reticulated spacer is integrally molded or formed separately from the auxiliary reticulated spacer.

The main reticulated spacer has first, second and third and fourth sides facing the inner wall of the central opening defined by the first, second and opposite sides of the frame, respectively. . The following method is good. That is, the main mesh spacer is inserted into the central opening of the frame through one gap left in at least one of each of at least two sides selected from the 1,2,3,4 sides. And a pair of opposing sides and at least the gap portion is filled with vulcanized rubber, which is connected to the opposite inner wall of the central opening at a portion corresponding to each of the at least two sides of the main net spacer and at least a portion of the gap. Eventually a single bond is formed between the frame and the main mesh spacer. The length of the minimum portion of the gap filled with vulcanized rubber is not critical, but is usually about 30 percent or more based on the total peripheral length of the main reticulated spacer.

The insertion of an auxiliary mesh spacer into each cut of the frame and then fixing it is usually performed after the entire skeleton of the gasket structure has been formed. However, when the frame is subsequently made of four strips of vulcanized rubber plates, the auxiliary mesh spacers are inserted into and fixed to the cut portions already formed in the respective strips, and the auxiliary mesh spacers fixed to the cut portions are assembled to the frame. To form.

As described above, the gaps filled with vulcanized rubber in each of the cutout portions and the central opening of the frame and any gaps not filled with this rubber have a width of 0.5 to 20 mm, preferably 1 to 10 mm.

If the gap is too small, the thickness of the vulcanized rubber formed by the vulcanization of the unvulcanized rubber already filled in this gap becomes uneven, resulting in deformation of the mesh spacer and poor connection of the mesh spacer with the frame. do. Thus, when such a gasket is used in the electrodialysis tank stack, leakage and non-uniform distribution of the liquid may occur. Moreover, during disassembly and reassembly of the device over a few hours, the spacer may be deformed out of position.

On the other hand, if the gap is too large, the deformation of the spacer tends to occur during the vulcanization of the unvulcanized rubber, since the unvulcanized rubber significantly moves laterally toward the mesh spacer during the vulcanization of the unvulcanized rubber applied to the gap. to be. Therefore, when a plurality of gaskets provided with such modified mesh spacers are configured in the electrodialysis tank, leakage of liquid is likely to occur during the operation of the electrodialysis tank.

The average thickness of each of the primary and secondary reticulated spacers to be inserted into the gasket frame is 92 percent to 130 percent, in particular 95 percent to 120 percent, more specifically 100 percent to 120 percent, based on the thickness of the gasket frame. The vulcanized rubber that fills in each gap and connects each of the mesh spacers and the frame has an average thickness of 92 percent to 130 percent, preferentially 100 percent to 120 percent or more, based on the thickness of the frame. If the average thickness of each of the mesh spacer and the vulcanized rubber is too small or too large, liquid leakage is likely to occur when such a gasket is used in an electrodialysis tank. Moreover, in order to prevent the leakage of the liquid, a large tightening force is required, which damages the raw materials of the frame and other members constituting the electrodialysis tank, resulting in distortion of the electrodialysis dialysis chamber and uneven distribution of the liquid.

The gasket structure of the present invention can advantageously be used in an electrodialysis bath. For example, when the gasket of the present invention is used in an electrodialysis tank, an alternating ion exchange membrane is firmly supported therebetween, and even if the difference in hydrostatic pressure between the dilution dialysis chamber and the concentrated dialysis chamber increases, the deformation of the spacer is increased. This does not occur because each spacer and frame constituting the gasket each have the same or similar thickness as the frame. Moreover, the unitary structure of each meshed spacer and frame of the gasket according to the present invention allows the leakage of liquid to be first without deformation of the ion exchange membrane, and functions to maintain a high level of limited current density during operation of the electrodialysis tank. Moreover, the electrodialysis tank using the gasket of the present invention can be disassembled and assembled in a short time, which is a clear improvement in not only operating efficiency but also maintenance of the apparatus.

Example 1

HS hardness 75 ° (measured by Japanese Industrial Standard K6301-1975) and 0.5mm thick vulcanized natural rubber film, cut into 4 strips, 2 strips 30mm wide and 698mm long, 67mm wide Two strips of length 356 mm are obtained. These strips are arranged to form a frame-like shape as shown in Fig. 3, so that two relatively large strips are placed on the upper and lower sides. The four parts, indicated by dashed lines in FIG. 3, are then fixedly connected by rubber-based adhesive to form a gasket frame like the frame of the drawing with a central opening with an area of 20.6 dm 2.

Thereafter, four bores of 22 mm diameter and three square holes of 39 mm x 39 mm are alternately formed in the first side (bottom) of the gasket frame having a relatively large width relative to the width of the adjacent side, and three bore of 22 mm diameter. And four square holes of 39 mm x 39 mm are alternately formed in the second side (upper side) of the gasket frame having a relatively large width compared to the width of the adjacent side. These bores and square holes are arranged at each side at equal intervals as measured between the alternating adjacent bore and square holes alternately so that the bores of the first side of the frame intersect directly from the square holes of the second side of the frame. It is sometimes molded.

The portions of the first and second sides of the frame between the finished hole of the frame and the central opening are cut to the same width as the width of the square hole to obtain the same gasket frame as shown in FIG. The gasket frame thus obtained is composed of a gasket frame body 12, a bore 13, a cut portion 12 a and a central opening 12 b .

A fifth from a polypropylene mesh with a pitch of 0.56 mm, 5 mm in one direction and 3 mm in the direction intersecting it, and an inclined lattice pattern with a shore hardness of 100 (measured by ASTM D 1484-59T). A mesh grid as shown in the figure is produced. The mesh spacer is sized to leave a 1 mm gap between the spacer and the inner inner wall of the frame when it is inserted inside the gasket frame, along the entire perimeter of the spacer. The hole 16 having a diameter of 22 mm has a hole formed in the convex portion of the gasket frame in line with the bore of the gasket frame when the mesh spacer is inserted inside the gasket frame to leave a gap of 1 mm along the entire inner wall of the gasket frame. The convex portion 15 of the reticulated spacer is formed in such a positional relationship. The mesh spacer thus prepared is inserted into the gasket frame while leaving a gap of 1 mm along the entire inner wall of the gasket frame while leaving a gap of 1 mm along the entire inner wall of the gasket frame.

On the other hand, based on the unvulcanized natural rubber, a vulcanizing agent corresponding to 1 weight percent is added to the unvulcanized natural rubber. Unvulcanized natural rubber is used to prepare a thin plate of 0.5 mm thickness. This thin plate is cut into a size of 500 mm in width and 700 mm in length. Subsequently, the thin plate thus prepared is punched out as shown in FIG. The molded unvulcanized natural rubber has an outer axis dimension of 1 mm larger and a width of 5 mm over its entire periphery than the dimensions of the spacer prepared above.

A folding agent made of unvulcanized natural rubber is applied to the entire inner wall of the gasket frame. Subsequently, the unvulcanized natural rubber prepared above with the shape as shown in FIG. 6 is placed in a mesh spacer already inserted into the inside of the gasket frame, and the unvulcanized rubber is lightly pushed against the inner wall of the frame body by hand. The outer wall of unvulcanized natural rubber is connected to the inner wall of the frame body. The unvulcanized natural rubber portion and the applied adhesive are heat pressed using a conventional heat frame, and the periphery of the reticulated natural rubber is sandwiched in the unvulcanized natural rubber, whereby the unvulcanized natural rubber is vulcanized to obtain a gasket frame and a reticulated spacer. Make the joints of The gasket structure of the electrodialysis bath thus prepared is shown in FIG. In FIG. 7, number 12 refers to the gasket frame body, number 13 to the conduit forming bore, number 16 to connect the conduit forming hole and number 17 to connect the hole 16 to the effective current flow region. A 26 mm wide passage formed by the spacer, number 18 denotes both base ends of the cut, number 19 denotes an opening defined by both base ends, number 14 the spacer for the active current flow region, and number 20 the frame. It refers to vulcanized natural rubber that connects the body 12 and the peripheral portions of the spacer to form a single joint.

Substantially, the same process as described above was repeated, and 300 gaskets each having a width of 0.5 mm and an effective current flow area of 19.6 dm 2 were installed in seven passages each having a width of 26 mm connecting the holes to the effective current flow area. Prepare. The average thickness of the vulcanized natural rubber 20 of each of the 300 gaskets shown in FIG. 7 is 0.53 mm.

K-101(일본국, 아사히 가세이 고교 가부시기가이샤에 의해 제조 시판되는 양이온 교환막의 상표명)와 150장의 ACIPLEXA

(일본국 아사히 가세이 고교 가부시기가이샤에서 제조 시판되는 음이온 교환막의 상표명)가 다음의 전기 투석 실험용으로 사용하였다. 양 및 음이온 교환막, 그리고 희석 및 농축투석실용 가스켓이 교대로 된 층을 통상의 방법으로 서로의 상부에 놓고 스택으로 조립하여, 이 스택을 1쌍의 조임용 프레임으로 미리 조인다. 스택을 조립하는데 요하는 시각은 2인 작업자 기준으로 8시간 걸린다. 미리 조여진 스택을 필터 프레스형 전기 투석조의 1쌍의 전극사이에 배치하여, 수압 프레스로 클램프시킨다.300 gaskets are used in an electrodialysis tank having a dilution dialysis chamber and a concentration dialysis chamber with alternating cation exchange membranes and anion exchange membranes. Of these 300 gaskets, 150 gaskets are used as dilution dialysis chamber gaskets, which include three passages for supplying the liquid to be electrodialyzed to the effective current flow region and four passages for the electrodialysis liquid discharge. I have it. The remaining 150 gaskets are used as thickening dialysis chamber gaskets, which have four passages for supplying liquid to the effective current flow zone and three passages for discharging the concentrate. With ion exchange membrane, 150 pieces of ACIPLEX

K-101 (trademark of a cation exchange membrane marketed by Japan, Asahi Kasei Kogyo Co., Ltd.) and 150 pieces of ACIPLEXA

(Trade name of anion exchange membrane commercially available from Asahi Kasei Kogyo Co., Ltd., Japan) was used for the following electrodialysis experiments. The alternating layers of the positive and negative ion exchange membranes and the dilution and concentrated dialysis chamber gaskets are placed on top of each other in a conventional manner and assembled into a stack, which is pre-tightened with a pair of tightening frames. The time required to assemble the stack takes 8 hours for a 2 person operator. The pre-tightened stack is placed between the pair of electrodes of the filter press type electrodialysis tank and clamped with a hydraulic press.

Dilution (sea water) containing 1200 ppm sodium chloride is fed to the dilution and concentration dialysis chamber at a linear rate of 80 cm / mm. As leakage of diluent from the dialysis chamber of the electrodialysis tank to the outside (hereinafter often referred to as “external leakage”) is observed, the stack is retightened with a hydraulic press until no external leakage is observed. The tightening input per cm 2 of the effective current flow area required to completely eliminate external exposure (hereinafter referred to as “tightening pressure”) is 1.8 kg / cm 2 -gauge.

In order to measure the amount of dilution leak from the dilution dialysis chamber to the concentration dialysis chamber (hereinafter referred to as "internal leakage"), the supply of diluents from the concentration dialysis chamber and the dilution dialysis tank is stopped, and the concentration in the concentration dialysis chamber After dilution of the diluent, the diluent is fed only to the dilution dialysis chamber at a linear rate of 2 cm / sec for 1 hour. The results showed that the internal leak was 2 ml / min per dialysis chamber. Subsequently, the dilution solution containing 1200 ppm sodium chloride was fed again to the concentration dialysis chamber, and then to 20 to 20 parts by partial recycling system (refer to 1975 Advanced Technology for Wastewater Treatment, page 252-253 for partial recycling system). Dilution of the diluent is carried out at 25 ° C., and the concentration of sodium chloride in this dilution stream is adjusted to 500 ppm. It was also found that the current density was 0.52 A / dm 2. Furthermore, electrodialysis of the dilution continued for 10 days at a current density of 80 percent based on a current density of 80 percent based on the limit current density. As a result, the average desalination capacity was 3.2 m 3 / hr.

After disassembling the electrodialysis tank, reassembling the disassembled device and repeating it for three days, the gasket was deformed and the gasket was deformed and the time, tightening pressure and internal leakage required to assemble the device were measured. . The results are shown in Table 1.

TABLE 1

The device was disassembled into powder after 30 days of full operation and these parts were assembled back into the device and the limiting current density was measured. As a result, the limit current density was 0.52 A / dm 2 equal to the value measured after the initial assembly of the apparatus.

Example 2

Except that a vulcanized natural rubber sheet having a thickness of 1 mm was used, substantially the same procedure as in Example 1 was repeated to prepare a gasket frame having the same shape and size as that of Example 1.

Example 1 in a net made of polypropylene, an inclined lattice pattern with a thickness of 1.2 mm, a pitch of 5 mm in one direction and 3 mm in the direction intersecting it, a show hardness of 100 ° (measured with ASTM 1484-59T). Reticulated spacers with the same shape and size were made.

Subsequently, the same procedure as in Example 1 was repeated to prepare an unvulcanized natural rubber sheet having a thickness of 0.5 mm. The unvulcanized natural rubber thus prepared is punched into the shape shown in FIG. The molded unvulcanized natural rubber was 1 mm larger than the outer dimensions of the spacer provided above and 5 mm wide.

The periphery of the spacer prepared above is sandwiched between two unvulcanized natural rubbers 21 having a shape as shown in FIG. 6, while pushing the unvulcanized natural rubber strongly against the spacer shown in FIG. The distance between the outer periphery of the spacer sandwiched and the outer periphery of the unvulcanized natural rubber was 1 mm.

An adhesive of unvulcanized natural rubber is generally applied to the inner wall of the gasket frame body provided above. Spacer sandwiched between two unvulcanized natural rubbers as shown in FIG. 8 is inserted into the inside of the gasket frame body so that the outer wall of this unvulcanized natural rubber is in contact with the inner wall of the gasket frame body and bonded to them. Let's do it. The unvulcanized natural rubber portion and the added adhesive are vulcanized in the same manner as in Example 1 to form a single joint of the gasket frame and the mesh spacer.

Practically, the same procedure as described above was repeated to make 300 gaskets, each of which was provided with seven passages 26 mm wide, each having a hole connecting the effective current flow region, their thickness being 1 mm, the effective current flow. The area was 19.6 dm 2. The average thickness of the unvulcanized natural rubber of each of the 300 gaskets made above was 1.05 mm.

An electrodialysis tank was assembled in the same manner as in Example 1 using the gasket thus made and the same kind and number of ion exchange membranes as those used in Example 1. The time required to assemble the electric dialysis tank was eight hours for two workers.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density. As a result, the tightening pressure, internal leakage and limit current density were 1.2 kg / cm 2 -gauge, 1 ml / min / dialysis chamber and 0.57 A / dm 2, respectively. Electrodialysis of the diluent (sea water) was performed for 10 days at a current concentration of 80 percent based on the limiting current density. As a result, it was found that the average desalination volume was 3.4 m 3 / hour. Thereafter, the procedure of disassembling the electrodialysis tank, reassembling the disassembled device, and operating it for 10 days is repeated three times in the same manner as in the embodiment to check whether the gasket is deformed and the time required for reassembling the device Tightening pressure and internal leaks were measured. The results are shown in Table 2.

TABLE 2

After 30 days of full operation, the device was disassembled into parts and the assembly was reassembled to measure the limit current density of the device. As a result, the limit current density was 0.56 A / dm 2 equal to the value after initial assembly of the device.

Example 3

Practically repeating the same procedure as in Example 1, the vulcanized natural rubber sheet was 0.75 mm thick, four of which were made of two strips 35 mm wide and 693 mm wide, two 72 mm wide and 351 mm long. The gasket frame is made the same as the frame of the drawing, except that the gasket frame area as shown in the drawing is 19.6 dm 2. Subsequently, a gasket frame having seven cuts 39 mm wide and seven bores 22 mm in diameter was made in the same manner as in Example 1.

Pitch of 0.8 mm thickness, 5 mm in one direction and 3 mm in the intersecting direction, 37 mm wide and 44 mm long in a net of inclined lattice pattern polypropylene with show hardness (measured by ASTM D1484-59 T) 100 A spacer was made. When inserting the spacer into the cutout while leaving a gap of 1mm along the entire inner wall of the cutout of the frame body, a hole with a diameter of 2mm in such a positional relationship that the holes formed in each spacer coincide with the bore of the gasket frame It is formed on each spacer made above.

The passage spacer thus prepared is inserted into the cut portion of the frame body, leaving a gap of 1 mm along the entire inner wall of each cut portion of the frame body. On the other hand, the same procedure as in Example 1 was repeated to produce unvulcanized natural rubber having a thickness of 0.7 mm.

The thin plate thus produced is punched into a shape as shown in FIG. The molded unvulcanized rubber is 5 mm wide and has such an external dimension that the outer periphery of the molded unvulcanized rubber fits into each inner wall of the cutout of the gasket frame body.

An adhesive of unvulcanized natural rubber is applied to each front inner wall of the cutout of the gasket frame body. The unvulcanized natural rubber prepared above having a shape as shown in FIG. 9 is placed on the already inserted spacer of each cut portion of the gasket frame body. The outer wall of the unvulcanized natural rubber is brought into contact with the inner wall of each of the cut portions of the gasket frame body by lightly pushing the unvulcanized natural rubber into the inner wall of each cut portion of the gasket frame body by hand. Subsequently, the unvulcanized natural rubber portion and the coagulant are vulcanized in the same manner as in Example 1 to form a single joint of the gasket frame and the spacer. As shown in FIG. 10, the gasket structure thus made includes a gasket frame body 23, a conduit forming bore 25 a , a conduit forming hole 25 b , and a hole 25 b in the effective current flow region. It consists of a passage 24 formed by a connecting spacer, and an unvulcanized natural rubber 24 a which connects the spacer for each of the passages 24 and the gasket frame body 23 to form a single joint.

Substantially the same procedure as described above is repeated to make 300 gaskets. The width of the passage 24 and the average thickness of the unvulcanized rubber 24 a of each of the 300 gaskets thus made were 26 mm and 0.82 mm, respectively.

The mesh-shaped spacer for the effective current flow region of the inclined lattice pattern is inserted into the center opening of each gasket provided above so that the spacer and the gasket do not overlap each other.

The same kind and number of ion exchange membranes as used in Example 1 were used in the same manner as in the gasket Example 1 prepared above. The time required to assemble the device was 14 hours for two workers. Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density. As a result, the tightening pressure, internal leakage and limit current density were respectively 1.8 kg / cm 2 -gauge, 2 ml / min / dialysis chamber and 0.51 A / dm 2. Electrodialysis of the diluent (water) was treated for 10 days in the same manner as in Example 1. As a result, it was found that the average desalination volume was 3.3 m 2 / hour. Then, the time required for disassembling the electrodialysis tank, reassembling the disassembled apparatus, and repeating the series of operations three times in the same manner as in Example 1 to check the gasket for deformation and to reassemble the apparatus , Injection pressure and internal leakage were measured. The results are shown in Table 3.

TABLE 3

Attention: ^* 1 ^* 2

^* 1, if described with respect to ^* 2, after the first decomposition the device, to re-assemble the device was tried to measure the clamping pressure required does not provide any external leak. However, external leakage was observed even when the tightening pressure was increased to 5 kg / cm 2 -gauge. Therefore, the device was disassembled again and the cause of external leakage was investigated. As a result, it was found that a portion of the spacer for the effective current flow area inserted into the dilution dialysis chamber gasket No. 18 on the anode side overlapped with the gasket frame body. The device was reassembled by correctly reinserting it into the gasket with a spacer for the effective current flow area. The tightening pressure was measured again and found to be 1.7 kg / cm 2 -gauge. The assembly time, marked with a mark, ^* 1, was the total time required to reassemble the device after the first disassembly of the device and the time required to reassemble the device after calibrating the spacers to the effective current flow area. Tightening pressure and initial leakage, denoted as mark ^* 2, are the values measured after spacer calibration for the effective current flow area.

The device was disassembled into parts after 30 days of inactivity and the parts were reassembled and the limit current density of the device was measured. As a result, the limit current density was 0.51 A / dm 2, which is the same value measured after the device was first assembled.

Example 4

The vulcanized natural rubber sheet with a hardness of 75 ° (measured by Japanese Industrial Standard K6301-1975) and thickness of 0.75 mm was delivered in four strips, two of which were 35 mm wide and 693 mm long, and two 72 mm wide. It is a strip 351 mm long. Subsequently, the same procedure as in Example 1 was repeated to produce a gasket frame such as the frame shown in FIG. 1 with a central opening of 19.6 dm 2. Subsequently, a bore 13 having a diameter of 22 mm and a cut portion 12 a having a width of 39 mm and a length of 45 mm open to the central opening are alternately formed as shown in FIG. 4 in the same manner as in Example 1. Made a gasket frame.

Substantially the same procedure as in Example 1 was repeated to produce an unvulcanized natural rubber sheet having a thickness of 0.8 mm. The thin plate thus made was cut into strips 5 mm wide by 20 mm long. 5 mm in one direction and 3 mm in the intersecting direction, a net of inclined lattice-patterned polypropylene with a pitch, show hardness of 100 ° (measured by ASTM D1484-59T) and a thickness of 0.8 mm. A mesh spacer of 37 mm and 20 mm length was made. Thereafter, the above-described unvulcanized natural rubber strip having a width of 5 mm and a length of 20 mm is placed on the left and right sides of the spacer, and an overlap having a width of 4 mm of the spacer and the unvulcanized natural rubber is provided on both sides of the spacer. Lightly pressing the unvulcanized natural rubber with the existing press means, the left and right sides of the spacer 27 is fitted to the unvulcanized natural rubber 26 as shown in FIG. The average thickness of the unvulcanized natural rubber 26 sandwiched between the left and right sides of the spacer was 0.80 mm.

Three bond 1521 (commercially available from Japan, Three Bond), a rubber adhesive, was applied to the inner wall of each cut portion of the gasket frame body. The adhesive was applied to the entire outer wall of the vulcanized natural rubber sandwiched between the left and right sides of the spacer, and the spacer was inserted into each cut portion of the gasket frame body. The outer wall of the vulcanized natural rubber, which is fitted to the left and right sides of the spacer, comes into contact with the inner wall of each of the cut portions of the gasket frame body, thereby joining them. The unvulcanized rubber site and the applied adhesive are heat pressed to single bond the spacer and the gasket frame body inserted into each of the cut sites. The electrodialysis gasket structure thus prepared is shown in FIG. Referring to FIG. 12, number 28 designates a gasket frame body, number 30 a denotes a conduit forming bore, number 30 b the conduit forming hole, and number 29 the conduit forming hole 30 b to the effective current flow region 31. The passage formed by the spacers to be connected, number 32 denotes a spacer inserted in the effective current flow region 31, and number 26 a designates a vulcanized natural rubber.

Substantially the same procedure as described above was repeated to make 300 gaskets for the electrodialysis bath. The average thickness of the vulcanized natural rubber and the width of each of the passages 29, which are connected to the left and right sides of the spacer for each of the gasket frame body 28 and the passage 29 to form a single joint, were 26 mm and 0.81 mm, respectively. .

The electrodialysis tank was assembled using an ion exchange membrane having the same type and number as used in Example 1 and the gasket made as described above and the same method as in Example 1. The time required to assemble the device was 15 hours on a two-person basis.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density. As a result, it was found that the tightening pressure, internal leakage and limit current density were 4 kg / cm 2 -gauge, 3 ml / min / dialysis chamber and 0.52 A / dm 2, respectively. Subsequently, electrodialysis of the diluent (sea water) was performed for 250 hours at a current density of 80 percent based on the limit current density. As a result, the average desalination volume was 3.3 m 3 / span.

Example 5

Subsequently, the same procedure as in Example 4 was repeated, consisting of a gasket frame body 12, a bore 13, a cutting portion 12 a and a central opening 12 b , as shown in FIG. A gasket frame of 0.5 mm was made.

In Example 4 from a mesh of polypropylene with an inclined lattice pattern having a thickness of 0.50 mm, a pitch of 5 mm in one direction and a 3 mm in the intersecting direction, and a show hardness of 100 ° (measured by ASTM D1484-59T). A mesh spacer for the passage with the same size as shown was made. Thereafter, an unvulcanized natural rubber strip having a width of 5 mm and a length of 20 mm was prepared and placed on the previously prepared spacer in the same manner as in Example 4. The unvulcanized natural rubber strips placed on each of the spacers were lightly pressed in the same manner as in Example 4 to provide spacers 27 for each of the 26 mm wide passages defined by the vulcanized natural rubber 26 as shown in FIG. Get The average thickness of the vulcanized natural rubber 26 in which the left and right sides of the spacer were sandwiched was 0.52 mm. The spacer and gasket frame for each passageway were bonded in the same way as in Example 4 to make an electrodialysis gasket structure having the same shape as that of Example 4 as shown in FIG. Practically, the procedure as described above was repeated to make 300 gaskets for the electrodialysis bath. The average thickness of the vulcanized natural rubber, with the spacers for each of the gasket frame body 28 and the passage 29 connected to form a single joint, was 0.56 mm.

An electrodialysis tank was assembled in the same manner as in Example 1, using the same type and number of ion exchange membranes as those used in Example 1 and the gasket made above. The time required to assemble the device was 15.5 hours for two workers.

Substantially the same procedure as in the example of FIG. 1 was repeated to measure the tightening pressure, internal leakage, and limit current density. As a result, the tightening pressure, internal leakage, and limit current density were 5 kg / cm 2 -gauge, 5 ml / min / dialysis chamber, and 0.49 A / dm 2, respectively. Subsequently, electrodialysis of the diluent (sea water) was performed for 250 hours at a current density of 80% based on the limiting current density. As a result, the average desalination volume was 3.1 m 3 / hour.

Example 6

Vulcanized natural rubber with an HS hardness of 75 ° (measured by Japanese Industrial Standard K6301-1975) and a thickness of 0.75 mm was cut into four strips, two of which were 35 mm wide and 693 mm long, with the remaining two Is a strip 72 mm wide and 351 mm long.

Substantially the same procedure as in Example 1 was repeated to make a gasket frame as shown in FIG. 1 with a central opening having an area of 19.6 dm 2. Subsequently, on a gasket frame such as the frame of the drawing previously provided with bores having a diameter of 22 mm and 39 mm. The lower sides are alternately formed in the same manner as in Example 1. The bore, 39 mm in diameter, is then cut against the central opening to form a cut of 39 mm in width.

A passageway spacer as shown in figure 13 (a), which is a mesh of polypropylene in an inclined lattice pattern having a thickness of 0.75 mm, show hardness of 100 °, and a pitch of 3 mm in one direction and 3 mm in the direction intersecting with it. Made. The spacers thus made each had an arc shape with a width of 37 mm, a length of 25.5 mm, a radius of 18.5 mm at the upper portion, and a hole with a diameter of 22 mm. A hole formed in each spacer is formed so that when the spacer is inserted into each of the cut portions leaving a 1 mm gap along the entire inner wall of the cut portion of the frame body, the holes formed in each spacer coincide with the bore of the gasket frame. It is formed into such a positional relationship. The passage spacer thus made is inserted into each cut portion of the gasket frame prepared above, leaving a gap of 1 mm along the entire inner wall of each cut portion of the gasket frame.

The vulcanizing agent is added to 1 weight percell of unvulcanized natural rubber based on unvulcanized natural rubber. The 0.8 mm thick sheet is made from unvulcanized natural rubber by means of a calender (compression roller).

The thin plate thus prepared is cut into a horseshoe shape as shown in Fig. 13 (b). The horseshoe-shaped unvulcanized rubber thus prepared has an inner dimension of 29 mm, an outer dimension of 39 mm, a depth of 45 mm, a width of 5 mm and a thickness of 0.8 mm.

An adhesive based on unvulcanized natural rubber, which is used to prepare the unvulcanized natural rubber sheet, is applied to the entire inner wall of the cut portion of the gasket frame body. Subsequently, the horseshoe-shaped unvulcanized natural rubber prepared above is placed in a spacer already inserted in each cut portion of the gasket frame body. The outer wall of the horseshoe-shaped unvulcanized natural rubber contacts the inner wall of each cut portion of the frame body by lightly pushing the unvulcanized natural rubber toward the inner wall of the cut portion of the gasket frame body. The unvulcanized natural rubber and the applied binder were thermocompressed at 150 ° C. for 3 minutes in the same manner as in Example 1 to obtain a gasket structure for electrodialysis bath as shown in FIG. The gasket structure thus formed is a passage 34 formed by a spacer connecting the gasket frame body 33, the conduit forming bore 35 a , the conduit forming hole 35 b , and the conduit forming hole 35 b to the effective current flow region. ), connect the spacer and the gasket frame body 33 for each of these passages 34 in Fig vulcanized natural rubber (34 a), the effective current flow region 36, and claim 13 (a) to form a single seam It consists of a reticulated spacer 37 which is inserted into the effective current flow region 36 prepared using the same kind of net used to make the spacer as shown. Practically, the same procedure as described above was repeated to prepare 300 gaskets for electrodialysis baths. The average thickness of the vulcanized natural rubber 34 a in each of these 300 gaskets was 0.78 mm.

An electrodialysis tank was assembled in the same manner as in Example 1, using the same type and number of ion exchange membranes as those used in Example 1 and the aforementioned gasket. The time required to assemble the device was 14 hours for two workers.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density. As a result, the tightening pressure, internal leakage and limit current density were 2 kg / cm 2 -gauge, 5 ml / min / dialysis chamber and 0.53 A / dm 2, respectively. Subsequently, electrodialysis of the dilute solution (sea water) was carried out for 10 days at a current density of 80 percell based on the limit current density. The average freshwater and volume were found to be 3.3m 3 / hour. Thereafter, a series of processes of disassembling and reassembling the electrodialysis tank and operating for 10 days were repeated three times in the same manner as in Example 1 to check whether the gasket was deformed and required for reassembly of the device, tightening pressure and internal leakage. The time was measured.

The results obtained here are shown in Table 4.

TABLE 4

After the device was operated for a total of 30 days, the limit current density was measured again after disassembly and reassembly into parts, which was 0.53 A / dm 2, which was the same value measured after the initial assembly of the device.

Example 7

Subsequently, the same procedure as in Example 4 was repeated, to obtain a gasket frame as shown in the drawing, except that vulcanized natural rubber having an HS hardness of 90 ° (measured according to Japanese Industrial Standard K 6301-1975) was used. made. Subsequently, a bore having a diameter of 22 mm and a cut portion having a width of 33 mm and a length of 44 mm opened toward the central opening were alternately made in the same manner as in Example 1.

Pitches of 0.8 mm thickness, 5 mm in one direction and 3 mm in the intersecting direction, 37 mm wide for passages from polypropylene nets of inclined lattice pattern with a show hardness of 100 ° (measured according to ASTM D1485-59 T) The spacer was 43 mm long. Subsequently, when the spacers are inserted into each of the cutouts of the gasket frame leaving a gap of 1 mm along the entire inner wall of the cutout of the gasket frame body, such that the holes formed in each spacer coincide with the bore of the gasket frame. Positionally, holes 22 mm in diameter were formed in each of the spacers.

Substantially the same procedure as in Example 1 was repeated to produce unvulcanized natural rubber sheet having a thickness of 0.8 mm. The unvulcanized rubber sheet thus made was cut into L shape as shown in FIG. The L-type unvulcanized natural rubber was 5 mm wide, 44 mm long and 10 mm long. Two L-type unvulcanized natural rubbers were placed in each of the spacers already inserted in the cut. The inner wall of the cut portion was bonded in the same manner as in Example 1 to come into contact with the outer wall of the L-type unvulcanized natural rubber. Subsequently, the L-type unvulcanized natural rubber portion and the adhesive were thermocompressed in the same manner as in Example 1 to produce the same gasket structure for the electrodialysis bath as in FIG. The gasket structure thus formed is a passage having a width of 26 mm formed of a spacer for contacting the gasket frame body 38, the conduit forming bore 41 a , the conduit forming hole 41 b , and the conduit forming hole 41 b to the active current flow region. (39), the spacers for each of the passages (39) and gasket frame body (38) are connected to form a single vulcanized natural rubber (40).

Subsequently, the procedure as described above is repeated to make 300 electrodialysis gaskets in which the inner wall of each of the cutout portions facing the spacer and the spacer are not partly connected by the vulcanized natural rubber. The average thickness of each of the 300 gaskets made of unvulcanized natural rubber was 0.81 mm.

An electrodialysis tank was assembled in the same manner as in Example 1 using the gasket thus prepared and the same kind or number of exchange membranes as used in Example 1. The time required to assemble the device was 15 hours for two workers.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density, 5 kg / cm 2 -gauge, 4 ml / min / dialysis chamber and 0.50 A / dm 2, respectively. Subsequently, electrodialysis of the diluent (sea water) was performed at a current density of 80 percent based on the limit current density. As a result, it was found that the average desalination volume was 3.2 m 3 / hour.

Example 8

Subsequently, the same procedure as in Example 3 was repeated, using vulcanized natural rubber having an HS hardness of 55 ° (measured according to Japanese Industrial Standard K6301-1975) and a thickness of 0.75 mm to make a gasket frame and having a show hardness of 60 ° (ASTM D1484). Shown in FIG. 10 except that a net with an inclined lattice pattern with a pitch measured at -59 T, 0.9 mm thick, and 5 mm in one direction and 3 mm in the direction intersecting it was used as a spacer for passage. 300 gaskets were made.

Thus prepared gaskets were assembled in the same manner as in Example 1 using ion exchange membranes of the same kind and number as those used in Example 1. The time required to assemble the device was 14.5 hours for two workers.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density, 3 kg / cm 2 -gauge, 4 ml / min / dialysis chamber and 0.51 A / dm 2, respectively. Subsequently, electrodialysis of the diluent (sea water) was published for 10 days at a current density of 80 percent based on the limiting current density. As a result, the average desalination volume of this device was 3.3 m 3 / hour. Thereafter, the procedure of disassembling the electrodialysis tank and assembling the disassembled device and operating it for 10 days is repeated three times in the same manner as in Example 1 to check whether the gasket is deformed and to manufacture the device. Tightening pressure and internal leaks were measured.

The results are shown in Table 5.

TABLE 5

After the total operating time of 30 days, the device was disassembled into parts and the parts were reassembled and the limit current density was measured again, which was the same value as measured after the initial assembly of the device, 0.5 A / dm 2.

Comparative Example 1

The same rubber sheet as in Example 3 was used to make a gasket frame such as that of the drawing. Subsequently, seven bores having a diameter of 22 mm and seven cut portions having a width of 39 mm and a length of 45 mm opened toward the central opening of the frame were alternately installed in the same manner as in Example 1.

The same net raw material as used in Example 1 is cut to obtain a mesh spacer in which the passage spacer and the spacer for the effective current flow region are integrally formed. The spacer thus prepared has a 1 mm gap left along the front wall of the central opening and both walls of the cutout when the spacer is inserted inside the gasket frame. The distance between them is 20mm.

The gasket thus prepared is shown in FIG. In FIG. 17, number 42 refers to a gasket frame body, number 44 a denotes a conduit forming bore, number 44 b to a conduit forming hole, and number 42 a to a spacer connecting the hole 44 b to the active current flow region. The passage formed by this, and number 43 designates a spacer for the active current flow region.

Subsequently, the procedure as mentioned above was repeated to make 300 electrodialysis crude gaskets.

It was assembled in the same manner as in Example 1 using the same type and number of ion exchange membranes as those used in Example 1 and the gasket prepared above. The time required to assemble the electrodialysis tub was 22 hours for two workers.

Substantially the same procedure as in Example 1 was repeated to determine the tightening pressure, internal leakage and limit current density, 5 kg / cm 2 -gauge, 20 ml / min / dialysis chamber and 0.48 A / dm 2, respectively. Electrodialysis of the diluent (sea water) was carried out for 10 days at a current density of 80 percent based on the limiting current density, and the desalination volume of the device was 2.8 m 3 / hour.

After 10 days of operation, the apparatus was disassembled to examine the deformation of the gasket and the state of the ion exchange membrane, and an average of 1 mm of exchange membrane was observed between the inner wall of the gasket frame and the gap between the spacers.

Repeat the process of disassembling and reassembling the electrodialysis tank for 10 days and repeating it three times in the same manner as in Example 1 to check whether the gasket is deformed and the state of the ion exchange membrane, and the time required to reassemble the device. Was measured.

The results are shown in Table 6.

Comparative Example 2

Vulcanizer was added to 1 percent unvulcanized natural rubber based on unvulcanized natural rubber. From unvulcanized natural rubber, thin plates with a thickness of 0.37 mm are made by means of kender (compression roller). The thin plates thus prepared are cut to obtain two strips 35 mm wide and 693 mm long and two strips 72 mm wide and 531 mm long. A gasket frame as shown in the figure is prepared in the same manner as in the first embodiment. Subsequently, seven bores having a diameter of 22 mm and seven cut portions having a width of 39 mm opened at the center opening of the frame were alternately installed in the same manner as in Example 1.

Substantially the same procedure as mentioned above is repeated to make a gasket frame of 600 unvulcanized natural rubbers.

On the other hand, the passages were each made from a net made of polypropylene with a pitch of 0.80 mm, a pitch of 5 mm in one direction and a 3 mm in the direction intersected thereon, and an inclined lattice pattern having a show hardness of 100 ° (measured according to ASTM D1484-59 T) 300 reticulated spacers were formed integrally with a spacer for and a spacer for the active current flow region. These spacers were 3 mm larger than the inner dimensions of the gasket frame, respectively.

Thus, the spacers made above were placed on each of the unvulcanized natural rubber gasket frames so that the entire periphery of each cut and the central opening of the gasket frame were formed with a spacer and a 3 mm overlap of the gasket frame. Subsequently, an unvulcanized rubber adhesive was applied to the entire surface of the gasket frame on which the spacer was placed. An unvulcanized rubber adhesive was also applied to the entire surface of one side of the gasket frame of another unvulcanized natural rubber. The gasket frame was placed on the gasket frame on which the spacer had already been placed, and adhesive was applied while adjusting the position of the bores formed in the two gasket frames. A hole having a diameter of 22 mm was formed in each spacer of the cut site in such a positional relationship that the hole formed in each spacer of the cut site coincided with the bore of the gasket frame body. Gasket frame made of unvulcanized natural rubber sandwiched around the spacer is thermocompressed at 150 ° C for 10 minutes, and the vulcanized natural rubber is vulcanized together with the peripheral portion of the net spacer with unvulcanized natural rubber. A gasket structure is formed that is integrated with this mesh spacer. The electrodialysis gasket structure thus made is shown in FIG. 18 Fig number 38 to have a spacer which refers to a gasket frame body, and the number 46 a is connected to a conduit formed in the bore, No. 46 b has a conduit forming a hole, number 48 a has a hole 46 b in the effective current flowing area, For the passage formed, number 47 refers to the effective current flow region and number 48 refers to the spacer for the effective current flow region.

Subsequently, the same procedure as mentioned above was repeated to make 300 gaskets with seven channels of 26 mm width each connecting an active current flow region of 19.6 dm 2 and a hole to the active current flow region.

The average thickness of each of the 300 gaskets as shown in FIG. 18 was 0.78 mm. However, the thickness of each of the gaskets had a wide distribution, with a maximum thickness of 1.02 mm and a minimum thickness of 0.67 mm. In particular, the spacer-fitted gasket frame body was thick compared to other parts of the gasket frame, and its thickness was reduced toward the outside of the gasket frame.

An electrodialysis tank was used using the same type of gasket and ion exchange membrane as used in Example 1 above. The required tightening pressure was measured to provide no external leakage. However, external leakage was also observed when the tightening pressure was increased to 20 kg / cm 2 -gauge, meaning that it could not be used in practice.

Comparative Example 3

Substantially the same procedure as in Example 6 was repeated to make a gasket frame with seven cuts 39 mm wide.

For aisle as shown in figure 13 (a) from a net of inclined lattice pattern polypropylene with a thickness of 0.75 mm, a show hardness of 100 ° and a pitch of 3 mm in the direction intersecting 3 mm in one direction. Seven spacers were made. The spacer thus made has an arc shape with a width of 39 mm, a length of 25.5 mm, a radius of 19.5 mm at the top, and a hole with a diameter of 22 mm. The holes of the spacers were formed in such a positional relationship that the holes formed in the spacers coincided with the bores of the gasket frame when the spacers were fitted snugly in the cut portion. The seven spacers thus made fit the cutouts of the gasket frame.

On the other hand, substantially the same procedure as in Example 6 was repeated to make the unvulcanized natural rubber sheet. The thin plate thus produced was cut into a horseshoe shape having a width of 5 mm as shown in FIG. 13 (b). The horseshoe unvulcanized natural rubber has such an outer dimension that the outer periphery of the horseshoe unvulcanized natural rubber fits the inner wall of the cutout of the gasket frame. The horseshoe-type unvulcanized natural rubber was inserted into each of the cut portions of the gasket frame, and the entire outer wall of the horseshoe-shaped natural rubber and the entire inner wall of each of the cut portions were fixed with an adhesive made of unvulcanized natural rubber. The horseshoe type unvulcanized natural rubber portion and the applied adhesive were thermally pressed at 150 ° C. for 3 minutes in the same manner as in Example 6 to form a single joint of spacer and gasket frame body for each passage.

Practically as described above, the same procedure was repeated to make 300 gaskets with seven passages, each 26 mm wide.

The average thickness of the unvulcanized rubber in each of the 300 provided gaskets was 0.89 mm. However, for 82 of the 30 gaskets, the thickening of the vulcanized natural rubber protruding from the strings of the spacer and the seam surface of the spacer and the gasket frame body was observed. The thickness of this seam was thicker than that of the other sites, ie 0.84-0.96 mm. In 177 gaskets, several sites have been observed in which a single seam of the spacer and gasket frame body cannot be formed by vulcanized natural rubber.

The electrodialysis tank was assembled in the same manner as in Example 1 using the same type and number of ion exchange membranes as those used in Example 1 and the gasket provided above. Subsequently, an attempt was made to measure the tightening pressure required to provide no external leakage. However, an external leak was observed even when the tightening pressure was increased to 20 kg / dm 2 -gauge, meaning that the device could not be used in practice.

Comparative Example 4

Substantially, the same procedure as in Example 3 was repeated while using a vulcanized natural rubber having a thickness of 0.5 mm and an HS hardness of 75 ° (measured according to Japanese Industrial Standard K 6301-1975). Seven bores with a diameter of 22 mm were made. Pitch width 0.52 mm, pitch 5 mm in one direction and 3 mm in the intersecting direction, and a width of the passageway with a polypropylene net of inclined lattice pattern with a show hardness of 100 ° (measured according to ASTM D1484-59 T). Seven reticulated spacers 37 mm long and 44 mm long were made, and holes were formed in each of the resulting reticulated spacers in the same manner as in Example 3. The reticulated spacer with the holes thus made was inserted into each cut portion of the gasket frame prepared above in the same manner as in Example 3.

Substantially the same procedure as in Example 1 was repeated to produce an unvulcanized natural rubber sheet having a thickness of 0.5 mm. The resulting unvulcanized natural rubber sheet was cut to obtain a strip having a width of 5 mm and a length of 10 mm. Subsequently, the strip is placed vertically on both sides of the spacer at both base ends of each of the cuts, inwardly inserted into each of the cuts. The outer wall of the unvulcanized natural rubber facing each inner wall of each cut portion and the inner wall of each cut portion are fixed by an adhesive means of unvulcanized rubber. The unvulcanized rubber portion and the applied adhesive are thermocompressed in the same manner as in Example 1 to form a single joint of the gasket frame and the passage spacer. The thus prepared electrodialysis gasket structure is shown in FIG. In FIG. 19, number 49 designates a gasket frame body, number 52 a is a conduit forming bore, number 52 b is a conduit forming hole, and number 50 is formed on a spacer connecting the conduit forming hole to the effective current flow region. The passageway, and numeral 51, refers to a vulcanized natural rubber that connects the spacers for each of the passageways 50 and the gasket frame body 49 to form a single seam.

Subsequently, the same procedure mentioned above was repeated to make 300 gaskets that were partially connected by vulcanized natural rubber such that the spacers for each of the inner walls and passages of each cut of the gasket frame formed a single seam. The width of the passage 50 thus made and the average thickness of the vulcanized natural rubber 51 of each of the 300 gaskets were 26 mm and 0.54 mm, respectively.

The electrodialysis tank was assembled in the same manner as in Example 1 using the above-mentioned gasket and the same ion exchange membrane as those used in Example 1 and the same type to number of ion exchange membranes. However, during assembly, 72 of the 300 gaskets are vulcanized when the vulcanized natural rubber 51 of the gasket as shown in FIG. 19 alternately places the gasket and ion exchange membrane on top of each other while adjusting the position of the holes or bores. Burst or fall out of the dog's gasket. These damaged gaskets were used after the ruptured or broken areas were joined by conventional rubber adhesives. The time required to assemble the device was 24 hours for two people.

The tightening pressure required to provide no external leakage was measured to be 3 kg / cm 2 -gauge. Thereafter, the internal leakage amount was measured in the same manner as in Example 1. However, the internal leakage was as large as 30 ml / min / dialysis room, which meant that the device could not be used in practice. Subsequently, the device was disassembled to investigate the cause of the large internal leakage, and it was observed that the peripheral portions of the spacers were folded at each cut in relation to the twelve gaskets where the portions were not connected to the frame body by vulcanized natural rubber. It was also observed that spacers at each cut site were overlaid over the gasket frame body for two gaskets.

Comparative Example 5

Practically, the same procedure as in Comparative Example 4 was repeated to make a gasket frame with seven cuts. Seven spacers with holes for the passages were made in the same manner as in Comparative Example 4 and inserted into the cutouts of the gasket frame leaving a 1 mm gap along the entire inner wall of the cutouts. An unvulcanized natural rubber sheet was prepared in the same manner as in Example 1 and cut into strips having a width of 5 mm and a length of 10 mm.

Subsequently, the strip was vertically inserted into both sides of the passage spacer already inserted in each of the cut portions, so that the distance between the center of the unvulcanized natural rubber strip and the deepest portion of each cut portion was 20 mm. The outer wall of the unvulcanized rubber strip facing each inner wall of the cut portion and the inner wall of each cut portion were fixed with an unvulcanized rubber adhesive. The unvulcanized rubber site and the applied adhesive were thermocompressed in the same manner as in Comparative Example 4 to form a single seam of spacers for each of the gasket frame and the passage. The gasket structure thus made is shown in FIG. In FIG. 20, number 53 refers to the gasket frame body, number 56 a connects the conduit forming bore, number 56 b connects the conduit forming hole, and number 54 connects the conduit forming hole 56 b to the effective current flow area. The passageway formed by the spacers used herein refers to a vulcanized natural rubber that connects the spacer for the passageway 54 and the gasket frame body 53 to form a single seam.

Substantially, the procedure as described above was repeated to make 300 gaskets in which the spacers for each of the inner wall and the passage of each of the cutout portions of the gasket frame were partially connected by vulcanized natural rubber to form a single seam. The width of each of the passages 54 of the 300 gaskets thus made and the average thickness of the vulcanized natural rubber 55 were 26 mm and 0.54 mm, respectively.

The electrodialysis bath was assembled in the same manner as in Example 1 using the same type and number of ion exchange membranes as those used in Example 1 in the above-described gasket. During assembly, however, the vulcanized natural rubber 55 of the gasket 55 as shown in FIG. 20 was torn or dropped at 142 of 300 gaskets. These gaskets were used after the torn or peeled off areas were bonded with conventional rubber adhesives. The time required to assemble the device was 28 hours for two workers. The tightening pressure required to provide no external leakage was measured to be 3 kg / cm 2 -gauge. Thereafter, the internal leakage amount was measured in the same manner as in Example 1. However, the internal leakage was as large as 37 ml / min / dialysis room, which meant that the device could not be used in practice. Subsequently, the device was disassembled to investigate the cause of the large internal leaks, which resulted in the tearing or falling off of the seven vulcanized natural rubber gaskets. Abrupt wraps of spacers were observed at each cut across the frame body.

Claims (17)

In the whole dialysis gasket structure composed of a plurality of alternating cation exchange membranes 8, anion exchange membranes 7 and gasket structures 9 and 10 interposed therebetween, the gasket structure is a Consisting of a frame of vulcanized rubber sheet having a central opening 12b defined by opposing first and second sides and opposing third and fourth sides; The central opening 12b is made to receive a main mesh spacer 14 therein; A conduit forming bore 13 is formed on the first, second or opposite sides of the frame to make contact with the conduit forming holes 16 of the adjacent frames, making a direct corresponding relationship; A cutout portion 12a is formed on the first and second sides opposite to the frame and the third and fourth sides facing each other, and each of them independently corresponds directly to at least one of the conduit forming bores 13 of the adjacent frame. Not only has at least one conduit forming hole 16 made therethrough, but also has both base ends 18 defining an opening 19 open to the central opening 12b of the frame; Each of the cutting sites 12 has an auxiliary reticulated spacer 17 therein which defines a passageway to the central opening 12b; The auxiliary reticulated spacer 17 has at least both sides opposed to the inner wall of each cut portion 12a through the gap left between them at least at both sides thereof, thereby vulcanizing the minimum portion of the gap 20 The vulcanized rubber is connected between the inner wall of the cut-out portion 12a and at least both sides of the auxiliary reticulated spacer 17 at a portion corresponding to the minimum portion of the gap. An electrodialysis gasket characterized by forming a connection. 2. The at least one hole of claim 1, wherein the entire periphery of the auxiliary reticulated spacer 17 opposes the inner wall, which is each cut out portion, except for the portion corresponding to the opening of each cut portion, An electrodialysis gasket characterized by an auxiliary reticulated spacer. 2. The inner wall of the cut-out portion and the auxiliary mesh-shaped spacer do not contact each other while the two sides of the auxiliary mesh-shaped spacer face the inner wall of each cut-off portion, while at each cut-off portion at a portion spaced from the opening of the cut-off portion. An electrodialysis gasket, wherein the gap is defined by a short side, the gap constitutes a conduit forming hole at each cut portion. According to any one of claims 1 to 3, wherein the gasket structure is composed of a web-shaped spacer inserted into the central opening, the web-shaped spacers on the 1,2 sides and 3, 4 sides facing the frame. Each of which has opposite sides 1, 2, and 3, 4 opposite to the central opening, defined by at least one side of each of the at least two sides selected from the 1,2,3,4 sides; And the web-shaped spacer has a pair of opposing sides, the minimum portion of the gap being each of the inner wall of the central opening facing at the portion corresponding to the minimum portion of the gap. Characterized by being filled with vulcanized rubber connecting each of at least two sides of the main mesh space to form a single connection between the main mesh spacer and the frame. Gaskets for electrodialysis baths. The gasket for electrodialysis bath according to any one of claims 1 to 3, wherein each auxiliary mesh spacer is integrally formed with the main mesh spacer. The electrodialysis gasket according to any one of claims 1 to 3, wherein the frame is formed from a vulcanized rubber sheet having a HS hardness of 30 ° to 95 ° measured by a method specified in Japanese Industrial Standard K 6301-1975. 4. An electrodialysis gasket as claimed in claim 1, wherein the auxiliary reticulated spacer has an average thickness of 92 percent to 130 percent based on the thickness of the frame. The electrodialysis bath according to any one of claims 1 to 3, wherein the vulcanized rubber filled in each gap and connecting the respective auxiliary mesh spacers and the frame has an average thickness of 92 to 150 percent based on the thickness of the frame. gasket. The electrodialysis gasket according to any one of claims 1 to 3, wherein the width of the gap left between at least both sides of each auxiliary mesh spacer and the inner wall of the cut portion is 0.5 to 20 mm, respectively. 2. The two base end portions of claim 1, wherein portions corresponding to the minimum portions of the gaps respectively extend inwardly from the both base ends 18 defining the openings 19 of the respective cut portions 12a. And both base end portions of each of the base end portions are each about 5% based on the total length of the auxiliary reticulated spacer 17 facing the inner wall of the cut portion 12a. 11. A portion according to claim 10, wherein a portion corresponding to at least a portion of the gap has one or more portions interposed at respective inner ends of both base end portions, wherein the intervening portions are independent of each other from the base end inward. Continuous or discontinuous with respect to the extending base end portion, while the intervening portion is 30% or more based on the total length of the portion of the auxiliary reticulated spacer 17 opposite the inner wall of the cutting portion 12a, respectively. An electrodialysis gasket, characterized in that there is no one or more unconnected sites that extend continuously above. 12. The gasket structure according to claim 10 or 11, wherein the gasket structure is composed of a main mesh spacer inserted into the central opening, and the main mesh spacer is defined by opposing 1,2 sides and 3,4 sides of the frame. Said central openings having opposing 1,2 sides and 3,4 sides, respectively, facing each other through gaps left in at least one portion of at least two times selected from the 1,2,3,3 sides; and The main spacer has a pair of opposite sides, each of which has a minimum portion of each of the inner wall of the central opening facing each other at a portion corresponding to the minimum portion of the gap and at least two sides of the main spacer. An electrodialysis gasket, wherein the gasket is filled with vulcanized rubber to form a single connection between the spacer and the frame. 12. An electrodialysis gasket as set forth in claim 10 or 11 wherein each auxiliary reticulated spacer is integrally formed with the main reticulated spacer. The electrodialysis gasket according to claim 10 or 11, wherein the frame is formed from a vulcanized rubber sheet having an HS hardness of 30 ° to 95 ° measured by a method specified in Japanese Industrial Standard K 6301-1975. 12. An electrodialysis gasket as set forth in claim 10 or 11 wherein the auxiliary reticulated spacer has an average thickness of 92 percent to 130 percent based on the thickness of the frame. The electrodialysis gasket as set forth in claim 10 or 11, wherein the vulcanized rubber filled in each gap and connecting the respective auxiliary mesh spacers and the frame has an average thickness of 92 percent to 130 percent based on the thickness of the frame. The electrodialysis gasket as set forth in claim 10 or 11, wherein the width of the gap left between at least both sides of each auxiliary mesh spacer and the inner wall of the cut portion is 0.5 to 20 mm, respectively.

Images