JPS6348954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ion exchange membrane. Specifically, it is an ion exchange membrane suitable for use in filter press type batteries.

In this specification, a filter press type battery case is a type of battery case in which the ion exchange membrane is sandwiched and the battery case frame is tightened to substantially prevent the contents from leaking.

In addition, a tank is a general term for a device used to transfer ions through an ion exchange membrane using an electrical driving force, and is generally used for salt, salt, etc.
Ion-exchange membrane method electrolyzer that produces caustic alkalis through electrolysis of aqueous solutions of alkali metal salts such as potassium chloride, concentration and removal of substances that ionize in water such as salts, acids, and bases, and recombination of constituent ion species (metathesis), etc. Examples include a dialysis tank used, a reaction tank used for electrolytic oxidation or reduction of organic or inorganic substances, and the like.

Among the above-mentioned battery cases, in the case of a filter press type, a gasket made of rubber or the like is generally used for the tightening part. For this reason, the ion exchange membrane is generally assembled into the battery case frame while being sandwiched between two gaskets. In this type of case, a large number of battery case frames and ion exchange membranes are stacked one on top of the other, and the filter press type battery case is integrated by pressing from both ends to prevent leakage of the contents. There is a strong tendency for the surface pressure of the packing to increase, and the ion exchange membrane is strongly compressed. In addition to this, the packing, which is an elastic body, is deformed by the pressure. This deformation causes tensile stress to be applied to the sandwiched ion exchange membrane, which may eventually break. Particularly in the case of a battery case operated under heating of 50° C. or higher, the creeping property of the rubber seal increases, so that the deformation described above increases rapidly over time, resulting in rupture of the ion exchange membrane.

The present inventors have investigated the prevention of breakage at the packing contact surface of the ion exchange membrane for filter press type battery containers for electrolysis of aqueous alkali metal salt solutions using the ion exchange membrane method, and have investigated various methods for three possible methods. I conducted an experiment. That is, (1) make the hardness of the rubber seal appropriate; (2) Apply reinforcing material to the packing. (3)
Increase the strength of the ion exchange membrane. Of the above,
Regarding (1), it is possible to reduce the deformation of the rubber seal by increasing the hardness, but the sealing effect between the seal and the ion exchange membrane also decreases, making it necessary to increase the tightening pressure, and as a result, the amount of deformation decreases. It was necessary to compromise on both the sealing effect and the sealing effect. Next (2)
can reduce the amount of deformation to some extent, but when fabric rubber is used as a reinforcing material, gaps are created between the fibers, which may cause leakage (oozing). Also, manufacturing this type of packing is relatively expensive. Regarding (3), when a strong backing is applied to an ion exchange membrane, there is a tendency to generally increase the electrical resistance of the ion exchange membrane.

The present inventors took the above circumstances into full consideration and used a reinforcing material that has a higher tensile strength in the part that comes into contact with the packing (hereinafter also referred to as the packing contact surface) compared to the part where ion permeation actually occurs. Arrived at the ion exchange membrane.

In the present invention, it is preferable to use a frame-like strong reinforcing material around the entire periphery of the ion exchange membrane, but in some cases, a sufficient effect can be obtained by reinforcing only one of the opposite sides. . For example, in the case of a rectangular membrane surface, the long sides are generally more likely to break, so reinforcing only the long sides of the seal contact surface may be sufficiently effective.

As mentioned above, the feature of the present invention is that the strength of the packing contacting surface is higher than that of the part of the ion exchange membrane that substantially undergoes ion permeation, that is, the central part. The means for reinforcing the packing contact surface is not particularly limited, but includes, for example, means for applying or adhering high-strength resins, and means for adhering or embedding fibrous materials such as cloth. For these means, one must be selected that has high adhesiveness between the reinforcing material and the ion exchange resin constituting the ion exchange membrane. Another preferred embodiment is to carry the ion exchange resin on a backing material that uses high-strength weft threads or has a large number of threads placed at regular intervals in accordance with the width of the battery case. That is, by cutting a long backing material and applying it to the ion exchange membrane, a high-strength backing can be provided on the opposite side. Similarly, backing is used in which the strength of the ends is increased by using high-strength yarns for the warp yarns near both ends of the backing material or by increasing the number of threads. Of course, it is most preferable to strengthen the warp yarns at both ends of the backing material and the weft yarns at regular intervals.

As mentioned above, the backing constituting the ion exchange membrane can be easily configured in advance using known techniques by devising the method of weaving the cloth. Furthermore, there are methods such as partially sewing threads into the cloth that has been woven into a plain weave, tricot weave, etc., or patching another cloth, etc.
It can also be used as a backing material suitable for the present invention. The partially reinforced backing material thus obtained is laminated with a film of ion exchange resin or its precursor resin, or is coated with a resin paste or solution and then solidified. An ion exchange membrane is formed by membrane means.

In the present invention, it is necessary to reinforce the contact surface of the packing, and if this part has extremely high hardness compared to other parts, the fitting between the reinforcing material and the ion exchange resin part will be reduced. For this reason, the reinforcing material must also not be an extremely hard material.

This will be explained below with reference to the drawings. FIG. 1 is a diagram showing how an ion exchange membrane is applied to a filter press type battery case. In the figure, 1 is a battery case frame, 2 is a flexible packing such as rubber, and 3 is an ion exchange membrane. Electrodes 4 are installed in the battery case frame 1 to constitute a bipolar type battery case for aqueous alkali metal salt electrolysis.
This figure shows a type in which a large number of battery case frames 1, gaskets 2, ion exchange membranes 3, gaskets 2, and battery case frames 1 are stacked one on top of the other in order, and the leakage of the liquid content is prevented by tightening them from both outer ends. The liquid supply port, liquid drain port, etc. to each battery case frame are not shown. FIG. 2 shows one embodiment of the present invention, in which the ion exchange membrane 3 has reinforcing materials such as plastic sheets 5 attached around its four peripheries. Usually, a sheet with good adhesion to the ion exchange membrane, such as a resin having an ion exchange group, or an ion exchange membrane reinforced with backing, is attached using an adhesive or by heat fusion. Alternatively, a cloth-like material may be embedded by heating and pressing. In particular, when the ion exchange membrane that is the object of the present invention is in the form of a fluorine-based non-crosslinked ion exchange resin film laminated to a backing material, it is preferable to heat-fuse the same or similar ion exchange membrane, etc. .

In another embodiment, as shown in FIG. 3, the weft threads 6 are partially strengthened to match the size of the battery case. That is, a high-strength thread is used in the relevant portion, or a cloth with a large number of threads per unit width (number of threads) is used for the reinforcing backing of the ion exchange membrane. Optionally, such a fabric can also have the warp threads 7 at both ends equally strong. Preferably, the strength of each of the warp and weft threads is increased.

FIG. 4 shows an ion exchange membrane using the cloth as shown in FIG. This figure shows the case where only the weft threads are reinforced.

The ion exchange resin of the ion exchange membrane in the present invention is not particularly limited. In general, any form in which an ion exchange group is bonded to a polymer matrix of styrene/divinylbenzene, acrylic acid, methacrylic acid, etc. is sufficient. In addition, for electrolysis of alkali metal salts, etc., the following formula An ion exchange resin having the structure is preferred.

Furthermore, the ion exchange group is not particularly limited, and includes, for example, a sulfone group, a carboxylic acid group, a phosphate group, an acid amide group having active hydrogen, a cation exchange group such as a hydroxyl group,
Examples include anion exchange groups such as primary to tertiary amino groups and quaternary ammonium groups.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a mode of application of a filter press type battery case and an ion exchange membrane. FIG. 2 is a diagram showing the ion exchange membrane of the present invention. FIG. 3 is an example of backing used in the ion exchange membrane of the present invention.
FIG. 4 is a diagram of an ion exchange membrane using backing as shown in FIG. In the above drawing, 1 is a battery case, 2 is a packing,
3 represents an ion exchange membrane, 4 an electrode, 5 a reinforcing portion of the ion exchange membrane of the present invention, 6 a reinforcing weft yarn of the present invention, and 7 a warp yarn.

Claims (1)

[Scope of Claims] 1. An ion exchange membrane in which the part that contacts the packing attached to the battery case frame is reinforced with a reinforcing material that has a higher tensile strength than the part that substantially permeates ions. . 2. The ion exchange membrane according to claim 1, which is applied to a filter press type battery case. 3. The ion exchange membrane according to claim 1, wherein the ion exchange membrane comprises an ion exchange resin portion and a cloth-like reinforcing material. 4. The ion exchange membrane according to claim 1, wherein the ion exchange resin portion of the ion exchange membrane has substantially no crosslinked structure. 5. The ion exchange membrane according to claim 1, wherein the ion exchange resin portion of the ion exchange membrane is composed of a perfluorocarbon chain, and a cation exchange group is bonded to the side chain via an ether bond. 6. The ion exchange membrane according to claim 2, which is used in a filter press type alkali metal salt aqueous solution electrolytic cell. 7. The ion exchange membrane according to claim 1, which uses backing in which the number of weft threads is increased at regular intervals. 8. The ion exchange membrane according to claim 1, which is woven with high-strength weft yarns spaced at regular intervals. 9. The ion exchange membrane according to claim 1, which uses backing in which the number of warp yarns near both ends is increased. 10. The ion exchange membrane according to claim 1, wherein the vicinity of both ends is woven with high-strength warp threads.