JPS6260475B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a method of sandwiching an ion exchange membrane between porous electrodes with good watertightness, and is applicable in fields such as ion exchange membrane method salt electrolysis and electrodialysis. This invention relates to an effective method for attaching an ion exchange membrane.

(Prior Art) Ion-exchange membranes have usually been clamped and held between a large number of frame-shaped electrode frames having porous electrodes in the center with frame-shaped gaskets having the same shape as the electrode frames interposed therebetween.

In this case, it is difficult to distribute the tightening force uniformly over the entire frame-shaped electrode frame, the gasket, and the ion exchange membrane due to the manufacturing precision of the entire electrode frame.
The watertightness of the ion exchange membrane sandwich is not so good.

As a countermeasure for this, one or more continuous protrusions are formed around one side of one of the gaskets.
A method has been proposed in which the ion exchange membrane and one of the gaskets are in linear contact, thereby concentrating the tightening force to prevent leakage of the electrolyte and dialysate. Although this method has largely achieved its intended purpose, experience has shown that the electrolyte and dialysate slightly permeate through the ion exchange membrane. In addition to specific permeation, leakage of liquid that diffuses horizontally through the ion exchange membrane and seeps out to the cut edges of the membrane has also been observed, posing new problems in terms of leakage current and equipment corrosion.

The above-mentioned phenomenon of horizontal diffusion in the ion exchange membrane and seepage from the edges of the membrane can be avoided when the ion exchange membrane has a multilayer structure, uses fibrous fabric in the center, or uses a highly hydrophilic membrane. This phenomenon occurs frequently, and has been highlighted as a major problem, especially in recent years when these multilayer ion exchange membranes are used.

(Problems to be Solved by the Invention) When an ion exchange membrane is sandwiched between frame-shaped electrode bodies via a gasket having the same shape as the electrode bodies, it is of course important that the electrolyte and dialysate do not leak from the clamping part.
It is an object of the present invention to find a method for installing an ion exchange membrane in which the ion exchange membrane is diffused horizontally within the membrane and does not leak out of the electrolytic cell even if leakage occurs from the edges of the membrane.

(Means for solving the problem) As a result of intensive research in view of the above problems, the inventors of the present invention found that the size of the ion exchange membrane should be limited.
They discovered that the problem could be solved by providing two types of continuous protrusions on the gasket, and completed the present invention. That is, the gist of the present invention is that two gaskets having a shape substantially the same as the planar shape of the frame-shaped electrode frame are interposed between an anode body and a cathode body in which a porous electrode is installed in the central opening of a frame-shaped electrode frame. In the method for attaching an ion exchange membrane, the ion exchange membrane is larger than the central opening of the frame-shaped electrode frame and smaller than the size of the frame-shaped electrode frame, and one of the gaskets is attached. One sheet is smooth, and the other sheet has a plurality of convex shapes that are continuous all around the ion exchange membrane side, and one or more of the inner convex stripes are located around the ion exchange membrane. It is a low protrusion provided at the abutting position, and one or more protrusions on the outside are higher than the low protrusion, and the height of both protrusions is approximately equivalent to the thickness of the ion exchange membrane. The method of attaching an ion exchange membrane is characterized by using a gasket having a high protrusion that comes into contact with a frame-shaped electrode frame outside the periphery of the ion exchange membrane.

Hereinafter, the present invention will be explained in detail using the drawings.

Figure 1 shows a frame-shaped electrode frame A with a mesh-type electrode 4 attached, a smooth frame-shaped gasket 2, an ion exchange membrane 3, a gasket 1 with protrusions 8 and 9, and a frame-shaped electrode frame with a porous electrode 5 attached. Electrode frame C, smooth frame-shaped gasket, ion exchange membrane 3, protrusion 8,
9 is a longitudinal cross-sectional view showing a state in which gaskets 1 with numbers 9 are repeatedly arranged in this order. FIG.

When constructing an electrolytic cell, this positional relationship is maintained and tightened in the left and right direction. (Tightening mechanism,
Gas or liquid supply piping, etc. are not shown. ) The surface of one of the two gaskets has two types of protrusions, high and low.These protrusions are directed toward the ion exchange membrane, but the size of the ion exchange membrane does not reach the position of the high protrusions. The high protrusions do not come into contact with the ion exchange membrane, but only the electrode frame on the outer periphery of the protrusions, since the protrusions extend beyond the positions of the low protrusions.

FIG. 2 shows the size and positional relationship of the ion exchange membrane 3 with respect to frame-shaped electrode frames A and C in which the porous electrode 4 is attached to the opening 6, and the size of the ion exchange membrane 3 is It is larger than the electrode frame central opening 6 and smaller than the frame-shaped electrode frames A and C.

FIG. 3 is a plan view of the convex strip side of the gasket 1, which has almost the same shape as the frame-shaped electrode frames A and C. The frame-shaped portion of the gasket has one tall convex strip 8 on the outside and a short convex strip on the outside. Two strips 9, 9 are provided on the inside.

4 and 5 respectively show a view taken along the - line in FIG. 3; and a view taken along the - line in FIG.

In the above explanation, only the case where the plurality of short or tall protrusions are simply provided along the outer periphery of the gasket is explained, but the innermost one of the plurality of short or tall protrusions is If a part of the gasket is damaged and the electrolyte cannot be sealed, the liquid will leak between the next outer protrusion and the leaked liquid will flow around the entire circumference of the gasket, resulting in Because the inner ridge is partially damaged, it becomes useless as a whole, and the same thing can be said about the next ridge on the outer periphery, so the effect of damage to the ridge is extremely large.

Therefore, in the present invention, when a plurality of short or tall protrusions are provided, the effect can be further improved by providing connecting protrusions of the same height between the protrusions and creating a large number of sections between the protrusions. become a target. That is, even if the seal deteriorates in one part, the effect only affects the small section located outside of the seal, and the ridges in the remaining parts are effectively used.

Next, the porous electrode refers to an electrode having a porous shape that is easily water permeable and has a wide effective electrode area, including a mesh type and a punching plate type.

(Function) Since the gasket with protrusions is constructed in this way, the short protrusions come into sharp contact with the ion exchange membrane and work to improve watertightness between the front and back surfaces of the ion exchange membrane, while the tall protrusions sharply abuts against the frame-shaped electrode frame on the outside of the edge of the ion exchange membrane to prevent the liquid that has passed horizontally inside the ion exchange membrane and seeped from the edge from leaking out.

Furthermore, since liquid leakage is reduced and the ion exchange membrane is abutted and clamped at a portion closer to the outer periphery of the ion exchange membrane, the utilization efficiency of the ion exchange membrane becomes higher.

(Example) In Figures 1 to 5, frame-shaped electrode frames A and C
The central opening of the electrode frame is 300 mm x 1250 mm, the outer dimensions of the electrode frame are 350 mm x 1300 mm, gasket 2 is made of flat EPDM with a thickness of 1 mm, gasket 1 is placed on a substrate with a thickness of 1 mm, and a high convex strip with a height of 1.5 mm is placed on the outside. There are two low protrusions with a height of 1.0 mm on the inside, and the outer one of the low protrusions is a rectangular EPDM of 330 mm x 1280 mm.
The ion-exchange membrane is a 335mm x sulfonated fluorinated polyethylene laminate with a woven fabric made of polyethylene terephthalate fibers in the central layer.
Electrode frame using 1285mm and 0.5mm thick ion exchange membrane,
Tighten with gasket and place 300g/in the anode chamber.
Electrolysis was carried out for 24 hours through saline solution.

As a result, leakage of the electrolytic solution from the edge of the ion exchange membrane was observed, but no leakage phenomenon to the outside was observed due to the high ridges.

On the other hand, as a comparative example, the same electrolysis was performed with four low protrusions instead of the high protrusions, and outward leakage was observed, but leakage to the outside was already observed after 5 hours. .

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view showing the arrangement of the electrode frame, gasket, and ion exchange membrane, Figure 2 is a plan view showing the size relationship between the frame-shaped electrode frame and the ion exchange membrane, and Figure 3 is a vertical cross-sectional view showing the relationship between the electrode frame, gasket, and ion exchange membrane. A plan view of a gasket having protrusions of various heights, Fig. 4 shows a view taken along the - line in Fig. 3, and Fig. 5 shows a view taken along the - line in Fig. 3, respectively. The main codes used will be explained. A, C... Frame-shaped electrode frame, 1... Gasket with protrusions, 3... Ion exchange membrane, 6... Opening, 8... Tall protrusions, 9... Short protrusions.

Claims (1)

[Scope of Claims] 1. Two gaskets having substantially the same planar shape as the frame-shaped electrode frame are disposed between an anode body and a cathode body in which a porous electrode is installed in the central opening of the frame-shaped electrode frame. In the method of attaching the ion exchange membrane through the gasket, the ion exchange membrane is larger than the central opening of the frame-shaped electrode frame and smaller than the size of the frame-shaped electrode frame; One sheet is smooth, and the other sheet has a plurality of continuous convex shapes around the entire circumference on the ion exchange membrane side, and one or more convex lines on the inside of the plurality of convex lines are located around the ion exchange membrane. The outer protrusion or protrusions are higher than the lower protrusions, and the height of both protrusions is approximately equal to the thickness of the ion exchange membrane. An ion exchange membrane attachment method characterized by using a gasket which is a convex strip having a corresponding difference and abutting against a frame-shaped electrode frame outside the periphery of the ion exchange membrane.