JPH06279600A - Formation of groove on the surface of cation exchange membrane - Google Patents

Abstract

PURPOSE:To provide a large number of grooves having specific pkysical properties on the surface of the porous layer of a cation exchange membrane having in the surface thereof gas- and liquid-permeable porous layer having no electrode activity. CONSTITUTION:A cloth having a yarn fineness of 5 to 200 deniers and a yarn density of 20 to 200 yarns/inch is embedded by 5 to 70% of the thickness thereof in the surface of the porous layer of a cation exchange membrane, and then peeled off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating the surface of a cation exchange membrane used in an ion-exchange membrane method alkali chloride electrolytic cell, and more specifically, to a chlorine gas having a low cell voltage and particularly a low oxygen concentration at the anode. It is an object of the present invention to provide a processing method which is effective for producing a groove on the surface of a film and has a high stability of mass production without reducing the strength of the film as much as possible.

[0002]

2. Description of the Related Art As a method of electrolyzing an aqueous solution of alkali chloride to obtain alkali hydroxide and chlorine, a method using an ion exchange membrane which can be produced with lower energy consumption than the conventional mercury method or asbestos diaphragm method has been put into practical use. There is.

The applicants continued their studies to carry out electrolysis of an aqueous solution at a load voltage as small as possible, and as a result, the cation exchange membrane acted as an electrode on the surface facing at least one of the anode and cathode. It was found that the above object can be sufficiently achieved by using an electrolytic cell having a cation exchange membrane having a gas and liquid permeable porous layer, which was previously disclosed in JP-A-54-152416, JP-A-55
-11118 and so on.

The effect of reducing the electrolysis voltage by using such a cation exchange membrane having a porous layer on its surface depends on the type, porosity and thickness of the substance forming the porous layer. Even when the porous layer is made of a non-conductive material as described below, substantially the same voltage reduction effect is exhibited.

The present inventor has further studied the electrolytic cell of this type, and when a cation exchange membrane having a porous layer permeable to gas and liquid is used on the surface, the porous layer and the electrode are used. The lowest cell voltage is obtained when placed in contact with. However, in the case of this electrolytic cell, it has been found that the oxygen concentration in the chlorine gas generated at the anode cannot always be reduced as expected. Although the cause thereof is not necessarily clear, none of the above phenomena can be overlooked even in an industrial electrolytic cell.

The inventor of the present invention continued to study in order to suppress the occurrence of such a phenomenon. As a result, in the above-mentioned electrolytic cell, the surface where the cation exchange membrane having the gas and liquid permeable porous layer and the electrode contacted each other. It has been found that, by providing a groove on the surface of the porous layer of the cation exchange membrane so that continuous gaps are formed, the object can be sufficiently achieved in practical use.

The groove provided on the surface of the porous layer of the cation exchange membrane achieves the object of the present invention as long as a continuous gap is formed on the contact surface between the cation exchange membrane and the electrode as described above. However, the degree of achievement of the purpose varies depending on the shape, direction, number, etc. of the grooves.

According to the research conducted by the present inventor, the groove provided on the surface of the porous layer of the cation exchange membrane is disclosed in Japanese Patent Laid-Open No. 3918/1985.
4, the surface width is preferably 0.1 to 10 mm, particularly preferably 0.5 to 5 mm, and the depth is preferably 0.01 mm or more, particularly preferably 0. The length is from 0.5 mm to 1/2 of the film thickness. The groove pitch (distance between two corresponding points of adjacent grooves) depends on the size of the surface width of the groove, but is preferably 0.1 to 20 mm, particularly preferably 0.5 to 10 mm. . The pitch is preferably proportional to the width and increases with increasing width. The length of the groove is preferably 5 mm or more, particularly preferably 10 mm or more.

A method for forming these grooves is disclosed in Japanese Patent Laid-Open No. 60-1985.
No. 39184, it is proposed that a grooved roll or a plate-based heat transfer method be used.
A processing method capable of more stably mass-producing the groove on the surface of the porous layer of the cation exchange membrane and preventing the strength reduction of the cation exchange membrane due to the groove processing as much as possible is not yet known.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to use a cloth in which fibers are woven vertically and horizontally and use a cloth for cation exchange membrane as a part of the cloth. It has been found that peeling is better achieved after pressure contact with the surface of the porous layer and embedding.

In the present invention, a yarn having a denier of 5 to 200, particularly 10 to 100 denier is preferably used, and the yarn density is preferably 20 to 200 yarns per inch, especially 4 yarns.
Use 0 to 150 woven fabrics. As the yarn, organic or inorganic (including metal) fibers can be applied, and monofilament, multifilament, twisted yarn, flat yarn, and the like can be used, but organic fibers are more preferable because they are easily available. As the organic fiber, polyethylene terephthalate,
Polyamide, acrylic, polypropylene, cellulose,
Fluororesin, polyethylene, silk and other single yarns and mixed yarns can be applied. These are required to have a shape-retaining ability to withstand the temperature and pressure during surface processing, and for this purpose,
Fibers of polyethylene terephthalate, polyamide or fluororesin are particularly preferred.

As the cloth, the kinds and the number of the warp threads and the weft threads may be the same or different. Also, weave methods such as plain weave, twill weave, and leno weave can be used. These woven fabrics may or may not have apertures formed between the yarns depending on the relation between the yarn diameter and the yarn density, but the aperture ratio is preferably about 10 to 80%. Have. These cloths are 20
It will have an average intersection thickness of ˜350 μm.

As a method for processing the grooves on the surface of the cation exchange membrane using the above cloth, a cloth is placed on the porous layer side of the anode side surface of the membrane, and this is heated by two rolls. It is preferable to pass the gap between them in order to form continuously stable grooves. The temperature of the heating roll at this time is preferably set to a surface temperature of 60 to 230 ° C. to sufficiently soften the constituent polymer of the cation exchange membrane in order to remove internal strain due to groove processing.

The pressing force between the two rolls is preferably 5
~ 200 kg / cm width is used. A sufficiently softened cation exchange membrane is preferable because it can be processed at a width of 100 kg / cm or less.

At this time, it is preferable that the cloth to be grooved is filled with 5 to 70% of the intersection thickness. The depth of the groove at that time is preferably 50% or less, particularly 30% of the film thickness.
The following are preferred for the purpose of preventing a decrease in film strength. If it is less than 5%, it is difficult to form continuous grooves, and if it exceeds 70%, a strong tearing force acts on the cation exchange membrane in the peeling step in the final step, resulting in a decrease in membrane strength.

The embedded cloth leaves the heating roll portion together with the cation exchange membrane, and is then sufficiently cooled to be peeled from the cation exchange membrane at a temperature at which the constituent polymer of the cation exchange membrane has sufficient strength. This method is not continuous, but can also be achieved by flat plate pressing. The thickness of the porous layer on the surface of the cation exchange membrane and the depth of the groove are not necessarily required to have a predetermined relationship, but the depth of the groove is preferably larger than the thickness of the porous layer. The thickness of the quality layer is preferably 1 to 50 times, particularly preferably 1 to 20 times.

The cation exchange membrane having a porous layer permeable to gas and liquid on the surface used in the present invention is formed by binding particles to the membrane surface. The amount of particles forming the porous layer depends on the material and size of the particles, but according to the study by the present inventor, preferably 0.001 to 100 mg, particularly 0.002 per unit cm ^{2 of the} membrane surface.
~ 20 mg was found to be good. If the amount used is too small, the intended effect of the present invention cannot be achieved, and if the amount used is larger, the membrane resistance is increased, which is not preferable.

The particles forming the gas and liquid permeable porous layer provided on the surface of the cation exchange membrane of the present invention may be conductive or non-conductive as long as they do not function as electrodes.
Further, it may be formed of either an inorganic material or an organic material, but it is preferably composed of a material having a corrosion resistance against the polar liquid. Representative examples include metals or metal oxides, hydroxides, carbides, chlorides or mixtures thereof, carbon or organic polymers.

In a preferred specific example, the porous layer on the anode side is a group IV-A (preferably silicon) of the periodic table.
Germanium, tin, lead), group IV-B (preferably titanium, zirconium, hafnium), group V-B (preferably niobium, tantalum), iron group metal (preferably iron, cobalt, nickel), chromium, manganese Alternatively, simple substance or alloy of boron, oxide, hydroxide, nitride or carbide, polytetrafluoroethylene or tetrafluoroethylene copolymer, etc. are used.

On the other hand, on the cathode side of the cation exchange membrane, the same gas and liquid permeable porous layer as on the anode side should be provided.
It is more preferable for obtaining a low cell voltage. The porous layer in that case, in addition to the material used to form the anode-side porous,
Silver or silver alloy, stainless steel, carbon (activated carbon, graphite, etc.), silicon carbide (α or β type), further polyamide resin, polysulfone resin, polyphenylene oxide resin,
Polyphenine sulfide resin, polypropylene resin or polyimide resin is advantageously used.

In forming the porous layer, the above particles preferably have a particle size of 0.01 to 300 μm, particularly 0.1 to 1
Used in the form of a powder of 00 μm. In this case, if necessary, a binder such as a fluorocarbon polymer such as polytetrafluoroethylene or polyhexafluoroethylene, a cellulose such as carboxymethyl cellulose, methyl cellulose or hydroxyethyl cellulose, polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone or sodium polyacrylate. Binders or thickeners such as water-soluble substances such as polymethyl vinyl ether, casein and polyacrylamide are used. These binders or thickeners are preferably 0 to 50 relative to the above powder.
%, Especially 0.5 to 30% by weight.

At this time, if necessary, an appropriate surface active agent such as long-chain hydrocarbons and fluorohydrocarbons, and graphite and other conductive extenders are added to facilitate the bonding of particles to the film surface. be able to.

The binding of the particles or particle groups forming the porous layer to the surface of the ion exchange membrane is carried out by the above-mentioned conductive or non-conductive particles,
The binder or thickener optionally used is thoroughly mixed in a suitable medium such as alcohol, ketone, ether or hydrocarbon to obtain a paste-like product of the mixture, which is transferred or screened. It is applied to the film surface by printing or the like. Further, in the present invention, in place of the paste-like material of the mixture containing the particles, a syrup or slurry of the mixture is obtained, and the particles or particle groups are attached to the film surface by spraying or spraying the syrup or slurry on the film surface. To be

The particles or particles which form the porous layer adhered to the surface of the cation exchange membrane are then preferably pressed or rolled, preferably at 80-220 ° C, 1-
The particles are heated and pressure-bonded to the ion exchange membrane at 150 kg / cm ² , and preferably particles or a part of particles are embedded in the membrane surface.

The porous layer formed of particles or groups of particles bonded to the membrane surface in this way preferably has a porosity of 10% or more, particularly 30% or more, and a thickness of preferably 0.01 to 200 μm. , Especially 0.1-100μ
It is suitable that it is m and is smaller than the thickness of the cation exchange membrane.

The porous layer formed on the film surface may be formed as a dense layer in which a large number of particles are bonded on the film surface, or when the particles or particle groups on the film surface are other particles. Alternatively, it can be configured as a sparse single-layer structure in which the particles are independently bonded to the film surface without contacting each other.
In the latter case, the amount of particles used to form the porous layer can be significantly reduced, and in some cases, the means for forming the porous layer becomes easy.

In the present invention, the cation exchange membrane having a porous layer formed on the membrane surface has a cation exchange group such as a carboxylic acid group, a sulfonic acid group, a phosphonic acid group or a phenolic hydroxyl group, preferably A film made of a fluoropolymer is preferred. As such a film, for example, one having a copolymer structure of a vinyl monomer such as tetrafluoroethylene or chlorotrifluoroethylene and a fluorovinyl monomer containing an ion exchange group such as a sulfonic acid, carboxylic acid or phosphoric acid group is preferable.

It is particularly preferable to use a copolymer having the structures (a) and (b) represented by the following chemical formula 1.

[0030]

[Chemical 1] Wherein X is F, Cl, H or -CF _3, X 'is X
Or CF ₃ (CF ₂ ) _m ⁻ , m is 1 to 5, and Y
Is selected from those of formula 2.

[0031]

[Chemical 2] In Chemical formula 2, X, Y, and Z are both 0 to 10,
Z and Rf are selected from -F or a perfluoroalkyl group having 1 to 10 carbon atoms. In addition, A is -SO ₃ M, -COO
M or --SO ₂ which can be converted to these groups by hydrolysis
F, -CN, -COF or -COOR, M represents hydrogen or an alkali metal, and R represents an alkyl group having 1 to 10 carbon atoms.

The cation exchange membrane used in the present invention has an ion exchange capacity of preferably 0.5 to 4.0 meq / g dry resin, especially 0.8 to 20 meq / g dry resin. Is preferred. In order to provide such an ion exchange capacity, in the case of a cation exchange membrane composed of a copolymer composed of the polymer units of (a) and (b), the polymer unit of (b) is preferably 1 to 40 mol%, Particularly, it is suitable to be 3 to 25% mol%.

The cation exchange membrane used in the present invention does not necessarily have to be formed from one kind of polymer and need not have only one kind of ion exchange group. For example, a laminated film of two kinds of polymers having a smaller ion exchange capacity on the cathode side, a cation exchange membrane having a weak acid exchange group such as a carboxylic acid group on the cathode side and a strongly acidic exchange group such as a sulfonic acid group on the anode side. Can be used.

These cation exchange membranes are produced by various conventionally known methods, and these cation exchange membranes are preferably made of a fluoropolymer such as polytetrafluoroethylene, if necessary, such as a cloth or net. It can be reinforced with a woven fabric, a non-woven fabric, a metal mesh, a porous body, or the like. The thickness of the cation exchange membrane of the present invention is preferably 50 to 1000 μm, preferably 100 to 500 μm.

When the porous layer is formed on the surface of the cation exchange membrane on the anode side or the cathode side, and further on both sides, the membrane causes decomposition of the ion exchange groups contained therein. A suitable form of ion exchange group,
For example, in the case of a carboxylic acid group, the acid or ester type is preferable, and in the case of a sulfonic acid group, -SO ₂ F
It is preferably done in a mold.

Further, when the groove is formed on the surface of the cation exchange membrane having the gas and liquid permeable porous layer of the present invention, when the porous layer is provided on the cation exchange membrane surface. Similarly, when the exchange group of the cation exchange membrane is a carboxylic acid group, it is preferably carried out in an acid or ester type, and when it is a sulfonic acid group, in a —SO ₂ F type,
Preferably, it is a roll press or a flat plate press, the press temperature is preferably 60 to 280 ° C., the pressure is 0.1 to 100 kg / cm on the roll press, and 0.1 to 1 on the flat plate press.
It is performed at 00 kg / cm ² . Further, the formation of the porous layer and the formation of the groove may be performed simultaneously.

In using the cation exchange membrane of the present invention, any type of electrode may be used. For example, porous electrodes such as perforated plates, nets or expanded metals are used. For example, the major axis is 1.0 to 10 mm and the minor axis is 0.
5-10 mm, hole diameter 0.1-1.3 mm, opening rate 30-
Examples include 90% expanded metal, punched metal having a circular, elliptical, or rhombic opening, and a porosity of 30 to 90%. Further, a plate-shaped electrode having no opening may be used, but the present invention is more effective when the electrode has a smaller opening ratio. Further, in the present invention, it is possible to use a plurality of electrodes having different porosities.

As the anode material, a platinum group metal, a conductive oxide thereof, a conductive reduction oxide thereof or the like is usually used.
On the other hand, as the cathode, a platinum group metal, a conductive oxide thereof, an iron group metal or the like is used. Examples of platinum group metals include platinum, rhodium, ruthenium, palladium, and iridium, and examples of iron group metals include iron, cobalt, nickel, Raney nickel, stabilized Raney nickel, stainless steel, and alkali etching stainless steel (Japanese Patent Publication No.
9229), Raney nickel-plated cathode (Japanese Patent Laid-Open No. 54-112785), and rhodan nickel-plated cathode (Japanese Patent Laid-Open No. 53-115676).

If a porous electrode is used, the electrode can be formed from the material forming the anode or cathode itself. However, when a platinum group metal or a conductive oxide thereof is used, it is usually preferable to form the surface of an expanded metal of a valve metal such as titanium or tantalum by coating these substances.

When the electrode is arranged in the present invention, at least one of the anode and the cathode as described above, preferably,
Both are placed in contact with a gas and liquid permeable porous layer having grooves on the surface. On the other hand, a cation exchange membrane having a gas and liquid permeable porous layer having no groove on the surface or a cation exchange membrane having no surface porosity may be arranged in contact with each other or at intervals. You may arrange in advance. The contact between the electrode and the cation exchange membrane is more than pressing the both firmly, and the electrode is, for example, 0 to 20 kg in the porous layer.
/ Cm ² is preferably pressed gently.

In the present invention, when the porous layer is provided only on one surface of the cation exchange membrane on the anode side or the cathode side, the electrode arranged on the cation exchange membrane side without the porous layer is It can be placed in contact with or without contact with the cation exchange membrane surface.

In the present invention, the electrolytic cell may be a monopolar type or a bipolar type as long as it has the above-mentioned constitution. Further, the material constituting the electrolytic cell, for example, in the case of the anode chamber in the case of electrolysis of an alkali chloride aqueous solution, those resistant to the alkali chloride aqueous solution and chlorine, such as valve metal, titanium is used,
In the case of the cathode chamber, iron, stainless steel, nickel or the like resistant to alkali hydroxide and hydrogen is used.

The process conditions for carrying out the electrolysis of the alkali chloride aqueous solution in the present invention are the above-mentioned JP-A-54-1.
Known conditions as in 12398 can be adopted. For example, preferably 2.5 to 5.0 normal (N) aqueous solution of alkali chloride is supplied to the anode chamber, and water or diluted alkali hydroxide is supplied to the cathode chamber, preferably 80 ° C to 1 ° C.
It is electrolyzed at 20 ° C. and a current density of 10 to 100 A / dm ² . In such a case, polyvalent metal ions such as calcium and magnesium in the aqueous solution of alkali chloride cause deterioration of the cation exchange membrane, so it is preferable to make them as small as possible. In addition, an acid such as hydrochloric acid can be added to the alkali chloride aqueous solution in order to prevent the generation of oxygen at the anode as much as possible.

[0044]

EXAMPLES Example 1 Tetrafluoroethylene and CF ₂ ═CFO (CF ₂ ) ₃
COOCH ₃ is copolymerized with azobisisobutyronitrile as a catalyst in a trichlorotrifluoroethane solvent to form a copolymer of ion exchange capacity of 1.25 meq / g dry resin and an ion exchange capacity of 1.8. Milli-equivalent copolymer was prepared.

A film having a thickness of 20 μm having an ion exchange capacity of 1.25 meq and a film having a thickness of 145 μm having an ion exchange capacity of 1.45 meq are placed at 200 ° C. and 25 kg.
A laminated film was obtained by compression molding for 5 minutes under a pressure of / cm ² .

On the other hand, 10 parts by weight of zirconium oxide powder having a particle size of 1 μm, 0.4 parts by weight of methyl cellulose (having a viscosity of 1500 centipoise of a 2% by weight aqueous solution) and 1 part of water.
A mixture containing 9 parts by weight, 2 parts by weight of cyclohexanol and 1 part by weight of cyclohexanone was kneaded to obtain a paste. Using a Tetoron screen having a mesh number of 200 and a thickness of 75 μm, a printing plate having a screen mask having a thickness of 30 μm under the paste, and a squeegee made of polyurethane, the exchange capacity of the cation exchange membrane was 1.45. Screen printing was carried out on the surface of the side of the anode equivalent to the milliequivalent. The adhesion layer obtained on the film surface was dried in air.

On the other hand, an average particle size of 0.3 was similarly obtained on the other surface of the film having a porous layer on the side surface of the anode thus obtained.
μm α-silicon carbide particles were deposited. Thereafter, the particle layers on each membrane surface are pressure-bonded to the cation exchange membrane surface under the conditions of a temperature of 160 ° C. and a pressure of 30 kg / cm ² , whereby titanium oxide particles and silicon carbide particles are formed on the anode surface and the cathode surface of the membrane. , 1.0m per 1 cm ^{2 of} film surface
A cation-exchange membrane having a porosity of 0.7 g and 0.7 mg attached was prepared.

On the other hand, 3 made of polyethylene terephthalate
With 0 denier and 6 filaments,
A plain weave cloth was produced in which 90 fibers per inch were driven in both length and width. The intersection thickness of this cloth was 85 μm on average, and the porosity was 72% on average.

The anode side of the cation exchange membrane having a porous layer on both sides thus obtained and a cloth made of polyethylene terephthalate were put together, and a metal roll and a rubber hardness of 80 degrees were applied.
A pair of rolls made of a rubber roll having a lining thickness of mm was continuously hot pressed. At this time, the surface temperature of the metal roll is 170 ° C., and the surface temperature of the rubber roll is 95.
℃ was made. Further, the pressing force was set to 30 kg / cm width, and the passing speed was set to 40 cm / min.

The cloth embedded under such conditions was cooled until the surface temperature of the cation exchange membrane became 40 ° C. or lower, and then peeled off from the membrane surface at a rate of 40 cm / min. The average morphology of the grooves formed on the film surface was such that the surface groove width was 0.1 mm and the pitch was 0.
The depth was 28 mm and the depth was 0.03 mm. The film thickness is 1 in the groove
It was 43 μm and 173 μm in the grooveless portion.

The cation exchange membrane was immersed in a 25% by weight aqueous sodium hydroxide solution at 70 ° C. for 16 hours to hydrolyze the ion exchange groups. Punched metal of titanium (minor axis 4 mm, major axis 8 m) on the anode side of the film thus obtained
m) is an anode having a low chlorine overvoltage coated with a solid solution of RuO ₂ , iridium oxide and titanium oxide, and a SUS304 punched metal (short diameter 4 mm, long diameter 8 mm) on the cathode side in a 52 wt% caustic soda aqueous solution. , 150 ° C
The cathode, which has been subjected to etching treatment for 52 hours at room temperature, has a low hydrogen overvoltage, is brought into pressure contact with the cation exchange membrane, and 5N sodium chloride aqueous solution to which hydrochloric acid is added so that the pH of the anode chamber is 2 is used as the cathode. While supplying water to the chamber, keeping the sodium chloride concentration in the anode chamber at 3.5 N and the caustic soda concentration in the cathode chamber at 35% by weight, at 90 ° C, 30 A
Electrolysis was performed under the condition of / d _m ² α.

As a result, the current efficiency was 95%, the voltage was 28 V, and the oxygen concentration in the chlorine gas obtained at the anode was 0.3%.

The same cation exchange membrane was used at 90 ° C. for 2 hours.
A dumbbell with a width of 1 cm at the measuring part was placed in a 5% by weight aqueous solution of sodium hydroxide for 16 hours to hydrolyze the ion-exchange groups, and the aqueous solution was cooled to 23 ° C. and held for 2 hours or more. Was cut parallel to the groove. A dumbbell was attached to a low-velocity displacement type Instron type strength measuring device and pulled at a pulling speed of 50 mm / min. The obtained breaking strength was 6.6 kg / cm width and the elongation was 51%.

Comparative Example 1 The surface temperature of a grooved roll having 95 protrusions per inch was 170 ° C., and the surface temperature of a pair of rubber rolls having a rubber hardness of 80 ° and a lining thickness of 10 mm was 100 ° C. And pressurization force 30kg / cm width, passing speed 40
The cation exchange membrane having porous layers on both sides, obtained in the same manner as in Example 1 at a rate of cm / min, was pressed with the anode surface side facing the grooved roll side. After pressing, the film was peeled off from the grooved roll at a rate of 40 cm / min along the rubber roll.

The average form of the grooves formed on the film surface was 0.1 mm in groove width, 0.27 mm in pitch, and 0.03 mm in depth. The film thickness is 140μm in the groove and 170μ in the pear
It was m.

The grooved film obtained by the above production method was subjected to the same hydrolysis as in Example 1 and electrolyzed in the same electrolytic cell. As a result, the current efficiency was 95%, the voltage was 2.8 V, and the oxygen concentration in the chlorine gas obtained at the anode was 0.3%, which was exactly the same as in Example 1. Further, as a result of measuring hydrolysis and tensile strength under the same conditions as in Example 1, the breaking strength was 5.1 kg / cm width and the elongation was 2
It was 9%.

Example 2 Tetrafluoroethylene and CF ₂ ═CFOCF ₂ CF (C
F ₃ ) OCF ₂ CF ₂ COOCH ₃ is copolymerized with triazotrifluoroethane solvent using azobisisobutyronitrile as a catalyst to obtain an ion exchange capacity of 0.90 meq /
A copolymer of dry resin was obtained.

On the other hand, tetrafluoroethylene and CF ₂ = CF
OCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F was copolymerized in the same manner to obtain a copolymer having an ion exchange capacity of 0.91 meq / g dry resin.

The carboxylic acid polymer and the sulfonic acid polymer were coextruded to obtain a film having a thickness of 170 μm. The thickness of the carboxylic acid layer was 30 μm, and the thickness of the sulfonic acid layer was 140 μm. A 10 μm film was separately molded from the same sulfonic acid polymer.

On the other hand, a 100 denier flat yarn obtained by drawing a film made of polytetrafluoroethylene was twisted 500 times per 1 m, and a yarn made of polyethylene terephthalate consisting of 6 filaments with 30 denier melt-spun. Using four polyethylene terephthalate yarns alternately with one longitudinal and transverse polyethylene terephthalate yarn, a woven fabric was obtained in which the yarn density was 80 yarns per inch. The average intersection point thickness of this cloth was 115 μm. This cloth was placed between a metal roll heated to a surface temperature of 225 ° C. and a rubber roll lined to a surface hardness of 80 ° C. with a rubber hardness of 80 degrees and a thickness of 10 mm.
Roll pressing force was continuously pressed at a width of 40 kg / cm at a speed of 40 cm / min to adjust the thickness to 80 μm.

Next, using the same device, a pressing force of 40 kg / c
Sulfonic acid polymer, film having a thickness of 10 μm, cloth adjusted to have a thickness of 80 μm, sulfonic acid polymer 140 μm and carboxylic acid polymer 30 at a speed of 20 cm / min in m width
A μm coextrusion film was co-flowed and integrated.

For the porous layer, the zirconium oxide paste prepared in Example 1 was coated on the 10 μm side of the sulfonic acid polymer film of the integrated membrane with a roll coater, and then dried at a temperature of 100 ° C. for 2 minutes. The dry weight was 1.4 mg per cm ² .

Similarly, 0.5 mg / cm ² of dry weight of silicon carbide paste was applied to the carboxylic acid side. The same grooves as in Example 1 were formed on the sulfonic acid side. However, the surface temperature of the metal roll at this time was 200 ° C.

The cation exchange membrane was immersed in an aqueous solution of potassium hydroxide of 15% by weight and a dimethylsulfoxide solution of 30% by weight at 70 ° C. for 90 minutes to hydrolyze the exchange group. The membrane was then dried at 65 ° C for 30 minutes. further,
This film was immersed in a 2% by weight aqueous sodium hydrogencarbonate solution at 25 ° C. and the tensile strength was measured. As a result, the tensile strength was 4.5 kg / cm width and the elongation was 44%.

Comparative Example 2 A groove similar to that of Comparative Example 1 was formed in a laminated film containing a reinforcing cloth having porous layers on both sides, which was obtained in the same manner as in Example 2. However, the surface temperature of the grooved roll at this time was 210 ° C. The tensile strength of this film was measured in the same manner as in Example 2. As a result, the tensile strength was 4.3 kg / cm width and the elongation was 18
%Met.

[0066]

EFFECTS OF THE INVENTION A groove having predetermined physical properties can be stably mass-produced on the surface of a cation exchange membrane having a porous layer permeable to gas and liquid on the surface of the anode side and / or the cathode side, and groove processing can be performed. It is possible to prevent the strength of the cation-exchange membrane from being reduced as much as possible.

Claims (5)

[Claims] 1. A method for grooving a cation exchange membrane having a porous layer permeable to gas and liquid having no electrode activity on the surface of the porous layer, wherein the thickness of the yarn is 5 to 200 denier.
A method for grooving a surface of a cation exchange membrane, which comprises embedding a woven fabric having a yarn density of 20 to 200 yarns / inch in a range of 5 to 70% of its thickness and then peeling it off. 2. The groove on the surface of the cation exchange membrane has a continuous length of 1 mm or more, a surface width of 0.01 to 10 mm, and a depth of 0.01.
The groove processing method according to claim 1, which is not less than mm. 3. The groove processing method according to claim 1, wherein the cation exchange membrane is made of a fluorocarbon polymer having a sulfonic acid group, a carboxylic acid group or a phosphoric acid group. 4. The groove processing method according to claim 1, 2 or 3, wherein the cation exchange membrane has a porous layer permeable to gas and liquid having no electrode activity on the surface on the anode side and / or the cathode side. 5. The groove processing method according to claim 1, wherein the cation exchange membrane is reinforced with a cloth containing fibers of a fluoropolymer.