JP2018059103A - Ion exchange membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion exchange membrane excellent in electrolytic performance and damage of a carboxylic acid layer.SOLUTION: There is provided an ion exchange membrane having a layer A containing a fluorine polymer having a sulfonic acid group and a layer B containing a fluorine polymer having a carboxylic acid group, in which the layer A has a projection with height of 20 μm or more is formed on at least one surface of the membrane body in a cross section view, a plurality of aperture parts are formed on the surface of the layer A, and percentage of total area of the aperture parts to area of the surface of the layer A (aperture area percentage) is 0.4 to 15%, ion exchange capacity of the layer A is 1.18 to 0.98 milliequivalent/g and ion exchange capacity of the layer B is 0.98 to 0.87 milliequivalent/g.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ion exchange membrane. In particular, it relates to an ion exchange membrane used for alkaline chloride electrolysis.

Fluorine-containing ion exchange membranes have excellent heat resistance and chemical resistance.
It is widely used in various applications as an electrolysis diaphragm for ozone generating electrolysis, fuel cells, water electrolysis, hydrochloric acid electrolysis, etc., and is spreading to new applications.

Among these, in the electrolysis of alkali chloride for producing chlorine and alkali hydroxide, the ion exchange membrane method has become the mainstream in recent years. Various performances are required for ion exchange membranes used for alkali chloride electrolysis. For example, electrolysis can be performed with high current efficiency and low electrolysis voltage, the concentration of impurities (particularly alkali chloride, etc.) contained in the manufactured alkali hydroxide is low, or the film strength is high and the film is handled or electrolyzed. Performances such as the carboxylic acid layer not being damaged are sometimes required.

In response to the above requirements, the supply of an aqueous alkali chloride solution is improved by providing a convex shape on the surface of the fluorinated cation exchange membrane. For example, in Patent Documents 1 and 2 and the like, by improving the supply ability of the alkali chloride aqueous solution by forming a convex shape on the anode surface of the cation exchange membrane,
It is practiced to reduce the generated alkali hydroxide impurities and to reduce damage to the cathode surface.

Japanese Patent No. 4573715 Japanese Patent No. 4708133

In the techniques described in Patent Documents 1 and 2, although the convexity shape is formed on the surface of the film, the supply performance of the aqueous alkali chloride solution is improved, but the electrolytic performance and resistance to damage to the cathode surface are improved. From the viewpoint, there is still room for further improvement.

The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an ion exchange membrane having excellent electrolytic performance and resistance to damage to a carboxylic acid layer.

As a result of intensive studies to solve the above problems, the present inventors have made the ion exchange membrane a predetermined configuration and adjusted the ion exchange capacity to a specific range, so that the electrolysis performance and the carboxylic acid during electrolysis can be reduced. It has been found that the resistance to damage to the acid layer is dramatically improved, and the present invention has been achieved.

That is, the present invention is as follows.
[1]
A layer A containing a fluoropolymer having a sulfonic acid group;
A layer B containing a fluoropolymer having a carboxylic acid group;
Have
The layer A has a convex portion having a height of 20 μm or more on a cross-sectional view on at least one surface,
A plurality of apertures are formed on the surface of the layer A,
A ratio (aperture area ratio) of the total area of the apertures to the area of the surface of the layer A is 0.
4-15%,
The ion exchange capacity of layer A is 1.18-0.98 meq / g,
An ion exchange membrane, wherein the layer B has an ion exchange capacity of 0.98 to 0.87 meq / g.
[2]
The arrangement density of the convex portions on the surface of the layer A is 20-1500 pieces / cm ² .
The ion exchange membrane according to [1].
[3]
The thickness of the layer A is 50 to 180 μm,
The ion exchange membrane according to [1] or [2], wherein the layer B has a thickness of 5 to 40 μm.
[4]
The layer A includes a polymer of a compound represented by CF ₂ ═CF— (OCF ₂ YF) _a —O (CF ₂ ) _b —SO ₂ F;
The layer B comprises a polymer of _{CF 2 = CF- (OCF 2 CYF} ) c -O (CF 2) a compound represented by _d -COOR,
Here, the a is an integer of 0 to 2, the c is an integer of 0 to 2, and the b and d are 1
The ion exchange according to any one of [1] to [3], wherein Y is F or CF ₃ , and R is CH ₃ , C ₂ H _5, or C ₃ H _7. film.
[5]
The total area of the projection is a surface 1 cm ² per 0.01cm ² ~0.6cm ² of the layer A, [1] ~ ion exchange membrane according to any one of [4].
[6]
The ion exchange membrane according to any one of [1] to [5], which is used for ODC electrolysis.

  The ion exchange membrane of the present invention is excellent in electrolytic performance and resistance to damage to the carboxylic acid layer.

It is a cross-sectional schematic diagram which shows the one aspect | mode of the ion exchange membrane which concerns on this embodiment. It is a simplified perspective view which notched a part of 1st Embodiment of the ion exchange membrane concerning this embodiment used in order to demonstrate arrangement | positioning of an opening part and a communicating hole. It is a simplified perspective view which notched a part of 1st Embodiment of the ion exchange membrane which concerns on this embodiment used in order to demonstrate arrangement | positioning of a reinforcing core material. It is the elements on larger scale of area | region A1 of FIG. It is the elements on larger scale of area | region A2 of FIG. It is the elements on larger scale of area | region A3 of FIG. It is a conceptual diagram for demonstrating the aperture ratio of the ion exchange membrane which concerns on this embodiment. It is a cross-sectional schematic diagram of 2nd Embodiment of the ion exchange membrane which concerns on this embodiment. It is a conceptual diagram for demonstrating the exposure area rate of the ion exchange membrane which concerns on this embodiment. It is a cross-sectional schematic diagram of 3rd Embodiment of the ion exchange membrane which concerns on this embodiment. It is a cross-sectional schematic diagram of 4th Embodiment of the ion exchange membrane which concerns on this embodiment. It is a schematic diagram for demonstrating the method of forming the communicating hole of the ion exchange membrane in this embodiment. It is a mimetic diagram of one embodiment of an electrolyzer concerning this embodiment. It is a schematic diagram which shows the example in the case of applying the electrolytic cell which concerns on this embodiment to ODC (Oxygen Depolarized Cathode) electrolysis.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist. In the drawings, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[Ion exchange membrane]
The ion exchange membrane according to this embodiment is also referred to as a layer A containing a fluorinated polymer having a sulfonic acid group and a layer B containing a fluorinated polymer having a carboxylic acid group (hereinafter also simply referred to as “carboxylic acid layer”). And the layer A has a height of 20 on at least one surface in a sectional view.
a plurality of apertures are formed on the surface of the layer A, and the layer A
The ratio of the total area of the apertures to the surface area of the surface (aperture area ratio) is 0.4 to 15%
And the layer A has an ion exchange capacity of 1.18 to 0.98 meq / g, and the layer B
The ion exchange capacity is 0.98 to 0.87 meq / g. Since it is configured in this manner, the ion exchange membrane according to this embodiment is excellent in electrolytic performance and resistance to damage to the carboxylic acid layer (hereinafter also simply referred to as “current-carrying surface C damage”). That is, there are convex portions on the surface of the ion exchange membrane, and there are opening portions (hereinafter also simply referred to as “salt water supply holes”) serving as supply holes on the surface of the ion exchange membrane. Supply amount of alkali chloride aqueous solution (hereinafter simply “
Also referred to as “salt water supply”. ), The membrane damage resistance during electrolysis is improved, and the electrolysis performance is improved.

[Layer A]
In this embodiment, the layer A contains the fluoropolymer A having a sulfonic acid group. The fluorine-containing polymer A having a sulfonic acid group constituting the layer A is not limited to the following, but, for example, copolymerizes the following first group of monomers and second group of monomers, or It can be produced by homopolymerizing the second group of monomers.

Examples of the first group of monomers include, but are not limited to, vinyl fluoride compounds. As a vinyl fluoride compound, what is represented by following General formula (1) is preferable.
CF ₂ = CX ₁ X ₂ (1)
(In the general formula (1), X ₁ and X ₂ each independently represent F, Cl, H or CF ₃ .
)

The vinyl fluoride compound represented by the general formula (1) is not limited to the following,
Examples thereof include vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene and the like.

In particular, when the ion exchange membrane according to this embodiment is used as a membrane for alkaline electrolysis, the vinyl fluoride compound is preferably a perfluoromonomer, and is selected from the group consisting of tetrafluoroethylene and hexafluoropropylene. A fluoromonomer is more preferred. More preferred is tetrafluoroethylene (TFE).

Examples of the second group of monomers include, but are not limited to, vinyl compounds having a functional group that can be converted into a sulfone-type ion exchange group. As the vinyl compound having a functional group that can be converted into a sulfone-type ion exchange group, those represented by the following general formula (2) are preferable.
_{CF 2 = CFO- (CF 2 YFO} ) a - (CF 2) b -SO 2 F ··· (2)
(In General Formula (2), a is an integer of 0 to 2, b is an integer of 1 to 4, Y is F or CF ₃ , R
Represents CH ₃ , C ₂ H ₅ or C ₃ H ₇ . )

Specific examples of these include monomers shown below;
CF ₂ = CFOCF ₂ CF ₂ SO ₂ F,
CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F,
CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ CF ₂ SO ₂ F,
CF ₂ = CF (CF ₂ ) ₂ SO ₂ F,
CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] ₂ CF ₂ CF ₂ SO ₂ F,
_{CF 2 = CFOCF 2 CF (CF} 2 OCF 3) OCF 2 CF 2 SO 2 F.

Among _{them, CF 2 = CFOCF 2 CF (} CF 3) OCF 2 CF 2 CF 2 SO 2 F, and _{CF 2 = CFOCF 2 CF (CF} 3) OCF 2 CF 2 SO 2 F is more preferred.
There are no particular restrictions on the type of monomer combination constituting the polymer A, its ratio, the degree of polymerization, and the like. Further, the polymer A contained in the layer A may be a single type or a combination of two or more types. The ion exchange capacity of the fluorinated polymer A having a sulfonic acid group can be adjusted by changing the ratio of the monomers represented by the general formulas (1) and (2). More specifically, for example, the monomer represented by the general formula (1) and the monomer represented by the general formula (2) are copolymerized in a ratio of 4: 1 to 7: 1. .

Layer A may be a single layer or a two-layer structure. When the layer A is a single layer, the thickness is preferably 50 to 180 μm, more preferably 70 to 160 μm, from the viewpoint of sufficiently ensuring the electrolytic performance and the resistance to damage to the current-carrying surface C. When the layer A has a two-layer structure, the layer on the side in contact with the anode is the layer A-1, the polymer forming the layer A-1 is the fluoropolymer A-1, and the layer on the side in contact with the layer B is the layer A- 2. The polymer forming the layer A-2 is referred to as a fluoropolymer A-2. Layer A-
The thickness of 1 is 10 to 60 μm from the viewpoint of sufficiently ensuring the electrolytic performance and the resistance to the current-carrying surface C damage.
m is preferable, and the thickness of the layer A-2 is preferably 30 to 120 μm, more preferably 40 to 100 μm, from the viewpoint of sufficiently ensuring the electrolytic performance and the resistance to the current-carrying surface C damage. From the viewpoint of keeping the strength of the membrane body at a certain level or more, it is preferable to adjust the thickness of the layer A as described above.
About the thickness of the layer A, it can control to the above-mentioned range by employ | adopting the preferable manufacturing conditions mentioned later, for example.

[Layer B]
In the present embodiment, the layer B includes a fluoropolymer B having a carboxylic acid group. The fluorine-containing polymer having a carboxylic acid group constituting the layer B is not limited to the following, but, for example, copolymerizes the above-mentioned first group of monomers and the following third group of monomers, Or it can manufacture by homopolymerizing the monomer of the 3rd group.

Although not limited to the following as a 3rd group monomer, For example, the vinyl compound which has a functional group which can be converted into a carboxylic acid type ion exchange group is mentioned. As the vinyl compound having a functional group that can be converted into a carboxylic acid ion exchange group, those represented by the following general formula (3) are preferable.
_{CF 2 = CF (OCF 2 CYF} ) c -O (CF 2) d -COOR ··· (3)
(In General Formula (3), c represents an integer of 0 to 2, d represents an integer of 1 to 4, Y represents F or CF ₃ , and R represents CH ₃ , C ₂ H _5, or C ₃ H ₇ . Represents.)

In the above general formula (3), Y is preferably CF ₃ and R is preferably CH ₃ .

In particular, when the ion exchange membrane according to the present embodiment is used as an ion exchange membrane for alkaline electrolysis, it is preferable to use at least a perfluoromonomer as the third group of monomers. The alkyl group (R) does not have to be a perfluoroalkyl group in which all of the hydrogen atoms are replaced by fluorine atoms. Among these, for example, monomers shown below are more preferable.
CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ COOCH ₃ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ COOCH ₃ ,
_{CF 2 = CF [OCF 2 CF} (CF 3)] 2 O (CF 2) 2 COOCH 3,
CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ COOCH ₃ ,
CF ₂ = CFO (CF ₂ ) ₂ COOCH ₃ ,
_{CF 2 = CFO (CF 2)} 3 COOCH 2.
The third group of monomers may be used alone or in combination of two or more.
There are no particular limitations on the type of combination of the monomers constituting the polymer B, the ratio thereof, the degree of polymerization, and the like. Further, the polymer B contained in the layer B may be a single type or a combination of two or more types. The ion exchange capacity of the fluoropolymer B having a carboxylic acid group can be adjusted by changing the ratio of the monomers represented by the general formulas (1) and (3). More specifically, for example, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized in a ratio of 6: 1 to 9: 1. .

As the thickness of the layer B, from the viewpoint of sufficiently ensuring the electrolytic performance and the resistance to the current-carrying surface C damage,
5-40 micrometers is preferable, More preferably, it is 15-40 micrometers, More preferably, it is 15
˜30 μm. About the thickness of the layer B, it can control to the above-mentioned range by employ | adopting the preferable manufacturing conditions mentioned later, for example.

From the viewpoint described above, in this embodiment, the layer A is CF ₂ = CF— (OCF ₂ YF) _a −.
It contains a polymer of a compound represented by O (CF ₂ ) _b —SO ₂ F, and layer B contains CF ₂ ═CF— (OCF
₂ CYF) _c -O (CF ₂ ) _d -COOR, a polymer of a compound represented by
Is an integer from 0 to 2, c is an integer from 0 to 2, b and d are integers from 1 to 4, Y is F or CF ₃ , R is CH ₃ , C it is preferably ₂ H ₅ or C ₃ H _7. Further, the thickness of the layer A is 50 to 180 μm, and the thickness of the fluoropolymer layer B is 5 to 4
It is especially preferable that it is 0 micrometer.

As illustrated in FIG. 1, the membrane body 10 includes a first sulfonic acid group as an ion exchange group.
Layer (sulfonic acid layer: corresponding to the above layer A) 10a and a second layer (carboxylic acid layer: corresponding to the above layer B) laminated on the first layer 10a and having a carboxylic acid group as an ion exchange group 10b. Usually, in the ion exchange membrane 1, the first layer 10a which is a sulfonic acid layer is on the anode side (see arrow α) of the electrolytic cell, and the second layer 10b which is a carboxylic acid layer is on the negative side of the electrolytic cell (arrow β). Reference) is located. The first layer 10a is preferably made of a material with low electrical resistance. The second layer 10b preferably has a high anion exclusion property even if the film thickness is small. The term “anion exclusion” as used herein refers to a property that tends to prevent the penetration and permeation of anions into the ion exchange membrane 1. The second layer 10b has a film thickness as described above from the viewpoint of reducing current efficiency, reducing the quality of the alkali hydroxide obtained, and further improving resistance to damage to the cathode surface. Is preferably adjusted. By using the membrane body 10 having such a layer structure, the selective permeability of cations such as sodium ions tends to be further improved. In the present embodiment, the membrane body includes a first layer containing a fluorinated polymer having a sulfonic acid group, and a first layer containing a fluorinated polymer having a carboxylic acid group laminated on the first layer. And an opening is formed on the surface of the first layer.

(Convex)
As shown in FIG. 1, a plurality of convex portions 11 are formed on the surface of the membrane body 10. The convex portions in the present embodiment are formed on at least one surface of the membrane main body, have a height of 20 μm or more in a cross-sectional view, and the arrangement density on the surface of the membrane main body is 20 to 1500 / cm ^2.
It is preferable that Here, the convex portion refers to a portion having a height of 20 μm or more from the reference point at the lowest point on the surface of the ion exchange membrane 1. Arrangement density of the projections per surface 1 cm ² of ion-exchange membrane 1, from the viewpoint sufficiently supplying electrolyte membrane is preferably 20 to 1,500 pieces / cm ^2, at 50 to 1200 cells / cm ² More preferably. Further, to increase the water supply amount, from the viewpoint of reducing the energization surface C injury, it is preferable that the total area of the projection is a surface 1 cm ² per 0.01cm ² ~0.6cm ² of the layer A. About the height and arrangement | positioning density of a convex part, it can control to the above-mentioned range by employ | adopting the preferable manufacturing conditions mentioned later, for example. In the above control, the manufacturing conditions described in Japanese Patent No. 4573715 (Patent Document 1) and Japanese Patent No. 4708133 (Patent Document 2) may be employed.

The height, shape, and arrangement density of the protrusions described above can be measured and confirmed by the following methods. First, on the membrane surface in the 1000 μm square area of the ion exchange membrane, the lowest point is used as a reference. A portion having a height of 20 μm or more from the reference point is defined as a convex portion. As a method of measuring the height, “Color 3D laser microscope (V
K-9710) ". Specifically, from a dry ion exchange membrane, 10
A portion of cm × 10 cm is cut out, a smooth plate and the cathode side of the ion exchange membrane are fixed with double-sided tape, and set on the measurement stage so that the anode side of the ion exchange membrane faces the measurement lens. 10 each
In a cm × 10 cm membrane, the shape on the surface of the ion exchange membrane is observed in a 1000 μm square measurement range, and the convex portion is observed by measuring the height from the lowest point as a reference. be able to.

Moreover, about the arrangement | positioning density of a convex part, from the ion-exchange membrane, arbitrarily cut out three 10 cm × 10 cm membranes and averaged the values measured at 9 locations in a 1000 μm square measurement range for each 10 cm × 10 cm membrane. It is the value.

The shape of the convex portion is not particularly limited, but the convex portion preferably has at least one shape selected from the group consisting of a conical shape, a polygonal pyramid shape, a truncated cone shape, a polygonal frustum shape, and a hemispherical shape. In addition, the shape called a dome shape etc. is also included by hemispherical here.

(Open hole and communication hole)
A plurality of apertures 102 are formed on the surface of the membrane main body 10, and communication holes 104 that communicate the apertures 102 are formed inside the membrane main body 10 (see FIG. 2). The communication hole 104 refers to a hole that can serve as a flow path for cations generated during electrolysis or an electrolytic solution. By forming the communication hole 104 inside the membrane body 10, it is possible to ensure the mobility of cations generated during electrolysis and the electrolytic solution. The shape of the communication hole 104 is not particularly limited, and can be suitably set as appropriate.

An opening is formed on the surface of the membrane, and a communication hole that connects the openings is formed in the membrane, so that the electrolytic solution is supplied to the inside of the ion exchange membrane during electrolysis. Accordingly, since the impurity concentration in the film changes, the amount of accumulated impurities in the film can be reduced. In addition, when metal ions generated by the elution of the cathode and impurities contained in the electrolyte solution supplied to the cathode side of the film enter the inside of the film, an opening is formed on the film surface. ,
It becomes easy to discharge from the inside of the film, and the accumulated amount of impurities can be reduced. That is, the ion exchange membrane of this embodiment is a membrane that has high resistance to impurities generated on the cathode side of the membrane in addition to impurities present in the electrolyte solution on the anode side of the membrane.

It is known that when the aqueous alkali chloride solution is not sufficiently supplied, characteristic damage occurs in the layer near the cathode of the membrane. The opening portion in the present embodiment can improve the supply ability of the alkali chloride aqueous solution and reduce the damage generated on the membrane body cathode surface.

The opening portion 102 formed on the surface of the membrane body 10 has a part of the communication hole 104 opened on one surface of the membrane body 10. Here, the term “open” means that the communication hole is open from the surface of the membrane body 10 to the outside. For example, in the case where the surface of the membrane body 10 is covered with a coating layer to be described later, on the surface of the membrane body 10 after the removal of the coating layer, an opening area in which the communication holes 104 are open to the outside is formed. That's it.

The opening 102 may be formed on at least one surface of the membrane body 10, but may be formed on both surfaces of the membrane body 10. As long as the hole area ratio in the present embodiment is satisfied, the arrangement interval and shape of the apertures 102 on the surface of the membrane body 10 are not particularly limited, and the membrane body 10
Appropriate conditions can be appropriately selected in consideration of the shape and performance of the battery, the operating conditions during electrolysis, and the like. In particular, when the membrane body 10 has both the first layer 10a and the second layer 10b,
It is preferable that an opening 102 is formed on the surface of the first layer 10a. Impurities are often contained in the electrolytic solution supplied to the anode side during electrolysis, and therefore, an opening 102 is formed on the surface of the first layer 10a to be disposed on the anode side. Preferably it is. This tends to reduce the influence of impurities on the ion exchange membrane.

The communication hole 104 includes a first layer 10a side ((α) side in FIG. 1) of the reinforcing core member 12 and a second layer.
The layer 10b is preferably formed so as to alternately pass through the layer 10b side ((β) side in FIG. 1). With such a structure, the electrolyte flowing in the space of the communication hole 104 and the cation (for example, sodium ion) contained therein can be transferred between the anode side and the cathode side of the membrane body 10. As a result, since the cation flow in the ion exchange membrane 1 is less likely to be shielded during electrolysis, the electric resistance of the ion exchange membrane 1 tends to be further reduced.

Specifically, as shown in FIG. 1, in the cross-sectional view, the communication hole 104 formed in the vertical direction in FIG. 1 is shown in cross section from the viewpoint of exhibiting more stable electrolysis performance and strength. With respect to the reinforcing core material 12, the first layer 10a side ((α) side in FIG. 1) and the second layer 1
It is preferable that they are alternately arranged on the 0b side (the (β) side in FIG. 1). Specifically, the communication hole 104 is disposed on the first layer 10a side of the reinforcing core member 12 in the region A1, and the communication hole 104 is disposed on the second layer 10b side of the reinforcing core member 12 in the region A4. It is preferable.

In FIG. 2, the communication holes 104 are respectively formed along the vertical direction and the horizontal direction of the paper surface. That is, the communication hole 104 formed along the vertical direction in FIG. 2 allows the plurality of apertures 102 formed on the surface of the membrane body 10 to communicate in the vertical direction. The communication holes 104 formed along the left-right direction in FIG. 2 allow the plurality of apertures 102 formed on the surface of the membrane body 10 to communicate in the left-right direction. Thus, in this embodiment, the communication hole 104 may be formed along only one predetermined direction of the membrane body 10, but from the viewpoint of exhibiting more stable electrolysis performance,
It is preferable that the communication holes 104 are arranged in both the longitudinal direction and the lateral direction of the membrane body 10.

The communication hole 104 only needs to communicate with at least two or more opening portions 102, and the positional relationship between the opening portion 102 and the communication hole 104 is not limited. Here, the opening 102 and the communication hole 1
An example of 04 will be described with reference to FIGS. 4, 5, and 6. 4 is a partially enlarged view of region A1 in FIG. 1, FIG. 5 is a partially enlarged view of region A2 in FIG. 1, and FIG. 6 is a partially enlarged view of region A3 in FIG. Regions A1 to A3 illustrated in FIGS. 4 to 6 are all regions in which the opening 102 is provided in the ion exchange membrane 1.

In a region A1 in FIG. 4, a part of the communication hole 104 formed along the vertical direction in FIG.
Openings are made on the surface of the membrane body 10, thereby forming an opening 102. And
A reinforcing core 12 is disposed behind the communication hole 104. The portion where the opening portion 102 is provided is lined with the reinforcing core material 12, thereby suppressing the occurrence of cracks in the membrane when the membrane is bent. The mechanical strength of the ion exchange membrane 1 tends to be further improved.

In a region A2 in FIG. 5, a part of the communication hole 104 formed along the direction perpendicular to the paper surface of FIG. 1 (that is, the direction corresponding to the left-right direction in FIG. 2) is formed on the surface of the membrane body 10. It is exposed and the opening part 102 is formed by this. Further, the communication hole 104 formed along the direction perpendicular to the paper surface of FIG. 1 intersects with the communication hole 104 formed along the vertical direction of FIG. Thus, when the communicating hole 104 is formed along two directions (for example, the up-down direction and the left-right direction in FIG. 2), the opening part 102 is in the point which cross | intersects these.
Is preferably formed. Thereby, since electrolyte solution is supplied to the communicating hole of both the up-down direction and the left-right direction, it becomes easy to supply electrolyte solution to the inside of the whole ion-exchange membrane. As a result, the concentration of impurities in the film changes, and the amount of accumulated impurities in the film tends to be further reduced. Further, when metal ions generated by the elution of the cathode or impurities contained in the electrolyte solution supplied to the cathode side of the film enter the inside of the film, the inside of the communication hole 104 formed along the vertical direction Both the impurities to be transferred and the impurities to be transferred through the communication holes 104 formed along the left-right direction can be discharged to the outside from the opening portion 102. From this viewpoint, the amount of accumulated impurities is further reduced. Tend to be.

In a region A3 of FIG. 6, a part of the communication hole 104 formed along the vertical direction of FIG. 1 is exposed on the surface of the membrane main body 10, whereby the opening 102 is formed. Further, the communication holes 104 formed along the vertical direction with respect to the paper surface of FIG. 1 are formed along a direction perpendicular to the paper surface of FIG. 1 (that is, a direction corresponding to the left-right direction in FIG. 2). Intersects with the communication hole 104. Similarly to the region A2, the electrolytic solution is supplied to the communication holes in both the vertical direction and the horizontal direction in the region A3, so that the electrolytic solution is easily supplied to the entire ion exchange membrane. As a result, the concentration of impurities in the film changes, and the amount of accumulated impurities in the film tends to be further reduced. Further, when metal ions generated by the elution of the cathode or impurities contained in the electrolyte solution supplied to the cathode side of the film enter the inside of the film, the inside of the communication hole 104 formed along the vertical direction Impurities to be conveyed and communication holes 1 formed along the left-right direction
Both of the impurities transported in 04 can be discharged to the outside from the aperture 102, and from this point of view, the amount of accumulated impurities tends to be further reduced.

(Reinforced core material)
The ion exchange membrane 1 according to the present embodiment preferably has a reinforcing core material 12 arranged inside the membrane body 10. The reinforcing core material 12 is a member that reinforces the strength and dimensional stability of the ion exchange membrane 1. By disposing the reinforcing core 12 inside the membrane body 10, in particular, the ion exchange membrane 1
Can be controlled within a desired range. The ion exchange membrane 1 does not expand and contract more than necessary during electrolysis and can maintain excellent dimensional stability over a long period of time.

The configuration of the reinforcing core material 12 of the present embodiment is not particularly limited, and may be formed by spinning a yarn called a reinforcing yarn, for example. The reinforcing yarn here is a member constituting the reinforcing core material 12, which can impart desired dimensional stability and mechanical strength to the ion exchange membrane 1, and
The yarn that can exist stably in the ion exchange membrane 1. By using the reinforcing core material 12 obtained by spinning such reinforcing yarns, it is possible to impart more excellent dimensional stability and mechanical strength to the ion exchange membrane 1.

The material of the reinforcing core material 12 and the reinforcing yarn used therefor is not particularly limited, but is preferably a material having resistance to acids, alkalis, etc., and from the viewpoint of imparting long-term heat resistance and chemical resistance. Those containing a polymer are more preferred. Examples of the fluorine-containing polymer include, but are not limited to, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE). , Tetrafluoroethylene-hexafluoropropylene copolymer, trifluorochloroethylene-ethylene copolymer, and vinylidene fluoride polymer (PVDF). Among these, polytetrafluoroethylene (PTFE) is preferable from the viewpoints of heat resistance and chemical resistance.

The yarn diameter of the reinforcing yarn used for the reinforcing core material 12 is not particularly limited, but is preferably 20 to 300 denier, and more preferably 50 to 250 denier. The weaving density of the reinforcing yarn (the number of driving per unit length) is not particularly limited, but is preferably 5 to 50 / inch. The form of the reinforcing core material is not particularly limited, and for example, a woven fabric, a nonwoven fabric, a knitted fabric or the like is used. Among these, a woven fabric is preferable. Although the thickness of a woven fabric is not specifically limited, It is preferable that it is 30-250 micrometers, and it is more preferable that it is 30-150 micrometers.

In the present embodiment, the reinforcing core material 12 may be a monofilament or a multifilament. Moreover, it is preferable to use these yarns, slit yarns and the like.

The weaving method and arrangement of the reinforcing core material 12 in the membrane body 10 are not particularly limited, and may be suitably arranged in consideration of the size and shape of the ion exchange membrane 1, the physical properties desired for the ion exchange membrane 1, the usage environment, and the like. can do. For example, the reinforcing core material 12 may be arranged along a predetermined direction of the membrane body 10, but from the viewpoint of dimensional stability, the reinforcing core material 12 is arranged along a predetermined first direction, and It is preferable to arrange another reinforcing core member 12 along a second direction that is substantially perpendicular to the first direction (see FIG. 3). By disposing a plurality of reinforcing core members so as to be substantially perpendicular to the inside of the membrane body 10 in the longitudinal direction of the membrane body, there is a tendency that more excellent dimensional stability and mechanical strength are provided in multiple directions. For example, it is preferable that the reinforcing core material 12 (warp yarn) arranged along the longitudinal direction and the reinforcing core material 12 (weft yarn) arranged along the horizontal direction are woven on the surface of the membrane body 10. A plain weave woven by weaving up and down alternately with warps and wefts, or a twine weaving with wefts while twisting two warps, and weaving the same number of wefts into two or several warp yarns arranged in a line. It is more preferable to use a diagonal weave from the viewpoint of dimensional stability, mechanical strength and manufacturability.

In particular, the MD direction (Machine Direction direction) of the ion exchange membrane 1 and T
Reinforcement core 1 along both directions of D direction (Transverse Direction direction)
2 is preferably arranged. That is, it is preferable that plain weaving is performed in the MD direction and the TD direction. Here, the MD direction refers to the direction (flow direction) in which the membrane body 10 and various core materials (for example, reinforcing core material 12, reinforcing yarn, sacrificial yarn described later, etc.) are conveyed in the ion exchange membrane manufacturing process described later. TD direction refers to a direction substantially perpendicular to the MD direction. And MD
The yarn woven along the direction is called MD yarn, and the yarn woven along the TD direction is called TD yarn.
Usually, the ion exchange membrane 1 used for electrolysis is rectangular, and the longitudinal direction is often the MD direction and the width direction is often the TD direction. Reinforcement core 12 that is MD yarn and reinforcement core 12 that is TD yarn
By weaving, the dimensional stability and mechanical strength that are more excellent in many directions tend to be imparted.

The arrangement | positioning space | interval of the reinforcement | strengthening core material 12 is not specifically limited, Considering the physical property desired for the ion exchange membrane 1, a use environment, etc., it can be set suitably suitably.

(Aperture ratio)
The aperture ratio of the reinforcing core material 12 is not particularly limited, preferably 30% or more, more preferably 5
It is 0% or more and 90% or less. From the viewpoint of the electrochemical properties of the ion exchange membrane 1, the aperture ratio is 3
From the viewpoint of the mechanical strength of the ion exchange membrane 1, it is preferably 90% or less.

The aperture ratio here refers to the surface through which substances (electrolyte and cations (for example, sodium ions)) such as ions in the projected area (A) of either surface of the membrane body 10 can pass. The ratio (B / A) of the total area (B). The total surface area (B) through which substances such as ions can pass is the projected area of the ion exchange membrane 1 where cations, electrolytes, etc. are not blocked by the reinforcing core material 12 etc. contained in the ion exchange membrane 1 It can be said that

FIG. 7 is a conceptual diagram for explaining the aperture ratio of the ion exchange membrane according to the present embodiment. FIG.
FIG. 4 is an enlarged view of a part of the ion exchange membrane 1 and illustrates only the arrangement of the reinforcing core member 12 in the region, and illustration of other members is omitted. Here, the projected area (A of the ion-exchange membrane including the reinforcing core material 12 arranged along the vertical direction and the reinforcing core material 12 arranged in the horizontal direction.
) Is subtracted from the total projected area (C) of the reinforcing core material 12 to reduce the area (A
The total area (B) of the region through which substances such as ions can pass can be determined. That is, the aperture ratio can be obtained by the following formula (I).
Aperture ratio = (B) / (A) = ((A)-(C)) / (A) (I)

Among these reinforcing core materials 12, a particularly preferable form is from the viewpoint of chemical resistance and heat resistance.
A tape yarn containing PTFE or a highly oriented monofilament is preferred. Specifically, a tape yarn obtained by slitting a high-strength porous sheet made of PTFE into a tape shape, or 50 to 300 denier of highly oriented monofilament made of PTFE,
And it is a plain weave with a weaving density of 10-50 pieces / inch, and its thickness is 50-100 μm.
It is more preferable that the reinforcing core material is in the range of m. The aperture ratio of the ion exchange membrane containing such a reinforcing core is more preferably 60% or more.

The shape of the reinforcing yarn is not particularly limited, and examples thereof include round yarn and tape-like yarn. These shapes are not particularly limited.

(Aperture area ratio)
In the ion exchange membrane 1 of the present embodiment, the ratio of the total area of the apertures 102 to the surface area of the membrane body 10 where the apertures 102 are formed (the aperture area ratio) is 0.4 to 15%. It is. By controlling the area ratio of the pores within this range, the influence of the impurities in the electrolytic solution on the electrolytic performance is small, and stable electrolytic performance can be exhibited. When the hole area ratio is less than 0.4%,
When impurities contained in the electrolyte enter the ion exchange membrane 1 and accumulate in the membrane body 10,
An increase in electrolysis voltage, a decrease in current efficiency, and a decrease in the purity of the resulting product will occur. When the aperture area ratio of the present embodiment exceeds 15%, the strength of the film is reduced or the exposure of the reinforcing core material is increased. Since the ion exchange membrane 1 of the present embodiment has a high hole area ratio, even if impurities accumulate inside the membrane body 10, the flow of exhausting from the communication hole 104 to the outside of the membrane through the opening portion 102 is promoted. can do. Therefore, the influence of the impurities on the electrolysis performance is low, and stable electrolysis performance can be exhibited for a long time.

In particular, in alkali chloride electrolysis, alkali chloride used as an anolyte and alkali hydroxide used as a catholyte contain impurities such as metal compounds, metal ions, and organic substances. Has a great influence on the electrolysis voltage and current efficiency. However, by using the ion exchange membrane 1 of the present embodiment, the electrolyte is supplied to the inside of the ion exchange membrane during electrolysis. Accordingly, since the impurity concentration in the film changes, the amount of accumulated impurities in the film can be reduced. In addition, when metal ions generated by the elution of the cathode or impurities contained in the electrolyte supplied to the cathode side of the film enter the inside of the film, the impurities described above are formed in the opening portion 102 and the communication hole 104. Then, it can be transmitted to the outside of the membrane body 10 without any trouble. Therefore, it is possible to reduce the influence on the electrolytic performance due to impurities generated during alkali chloride electrolysis, and it is possible to maintain stable electrolytic performance over a long period of time. Furthermore, an increase in impurity (alkali chloride, etc.) concentration in the product alkali hydroxide can also be suppressed. In the ion exchange membrane 1 of this embodiment, from the viewpoint of reducing the influence of the impurities on the electrolysis performance and keeping the strength of the membrane constant, the aperture area ratio of the aperture 102 is 0.5 to 10%. It is preferable that it is 0.5 to 5%. The hole area ratio can be confirmed by the method described in the examples, and can be controlled to the above-described range, for example, by adopting preferable manufacturing conditions described later.

In the present embodiment, the opening area ratio of the opening portion is the surface of the ion exchange membrane.
It is the ratio of the area of the aperture to the projected area when the ion exchange membrane is viewed from above.

(Aperture density)
In the ion exchange membrane 1 of the present embodiment, the hole density of the hole portions 102 on the surface of the membrane body 10 is not particularly limited, but is preferably 10 to 1000 holes / cm ² , and is preferably 20 to 20.
More preferably, 800 pieces / cm ² . The hole density here means the number of the hole portions 102 formed in 1 cm ² of the surface of the film body 10 where the hole portions 102 are formed. The surface 1 cm ² of the membrane main body 10 is a projected area when the membrane main body 10 is viewed from above. If the aperture density of the apertures 102 is 10 / cm ² or more, the average area per aperture 102 can be reduced appropriately, which is a cause of a decrease in strength of the ion exchange membrane 1. It can be made sufficiently smaller than the size of a hole (pinhole) where cracks can occur. If the aperture density of the apertures 102 is 1000 / cm ² or less, the average area per aperture 102 is such that metal ions and cations contained in the electrolyte can enter the communication holes 104. Since it is sufficiently large, the ion exchange membrane 1 tends to supply or permeate metal ions and cations more efficiently. The hole density can be controlled in the above-described range by adopting preferable manufacturing conditions described later, for example.

(Exposed area ratio)
FIG. 8 is a schematic cross-sectional view of a second embodiment of the ion exchange membrane according to this embodiment. In the present embodiment, as shown in the ion exchange membrane 2 of FIG.
An exposed portion A5 in which a part of the reinforcing core material 22 is exposed may be formed on the surface of the film body 20 on which is formed. In the present embodiment, it is preferable that the number of the exposed portions is small. That is,
The exposed area ratio described later is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and the exposed area ratio is 0%. Most preferably it is not formed. Here, the exposed portion A5 refers to a portion where the reinforcing core material 22 is exposed to the outside from the surface of the membrane body 20. For example, when the surface of the membrane body 20 is covered with a coating layer to be described later, the membrane body 2 after removing the coating layer
A region where the reinforcing core 22 is exposed to the outside on the surface of 0. 5% exposure area ratio
In the case of the following, an increase in electrolytic voltage is suppressed, and an increase in the concentration of chloride ions in the obtained alkali hydroxide tends to be further suppressed. The exposed area ratio is calculated by the following equation, and can be controlled to the above-described range by adopting, for example, preferable manufacturing conditions described later.
Exposed area ratio (%) = (total projected area of exposed portions where a part of the reinforcing core material is exposed when the surface of the membrane body is viewed from above) / (projected area of the surface of the membrane body) ) × 100

In the present embodiment, the reinforcing core material 22 preferably contains a fluorinated polymer such as polytetrafluoroethylene (PTFE). When the reinforcing core material 22 composed of the fluorine-containing polymer is exposed on the surface of the membrane body 20, the surface of the exposed portion A5 may be hydrophobic. When the electrolysis gas or cation in the dissolved state is adsorbed on the exposed portion which is hydrophobic, the cation permeation through the membrane can be inhibited. In such a case, the electrolysis voltage increases, and the concentration of chloride ions in the resulting alkali hydroxide can increase. In the present embodiment, by setting the exposed area ratio to 5% or less, the existence ratio of the exposed portion that is hydrophobic can be within an appropriate range. There is a tendency that the increase of ions is effectively suppressed.

Further, the electrolytically generated gas in the dissolved state and the impurities of the electrolytic solution such as metal ions can adhere to the exposed portion, enter and permeate the inside of the film body 20, and become impurities in the caustic soda. In the present embodiment, by setting the exposed area ratio to 3% or less, adsorption, intrusion and permeation of impurities tend to be more effectively suppressed, so that higher purity caustic soda tends to be manufactured.

In particular, in the ion exchange membrane 2 of the present embodiment, the above-mentioned open area ratio is 0.4 to 15% and the above-mentioned exposed area ratio is 5% or less, so that the current efficiency due to impurities is reduced. In the case of alkaline electrolysis, the impurity concentration in the product caustic soda tends to be kept lower. Further, since the increase in the electrolysis voltage is also suppressed, there is a tendency that more stable electrolysis performance can be exhibited.

In the present embodiment, the exposed area ratio of the exposed portion is the sum of the projected areas of the exposed portions formed on the reinforcing core relative to the total projected area of the reinforcing core when viewed from the top, It becomes an index indicating how much the included reinforcing core material is exposed. Therefore, the exposed area ratio of the exposed portion can be directly calculated by obtaining the projected area of the reinforcing core and the projected area of the exposed portion, but is calculated by the following formula (II) using the above-described aperture ratio. You can also. Here, it demonstrates more concretely, referring drawings. FIG. 9 shows an ion exchange membrane 2 according to this embodiment.
It is a conceptual diagram for demonstrating the exposure area rate of. FIG. 9 is an enlarged view of a portion of the ion exchange membrane 2 as viewed from above, and only the arrangement of the reinforcing core material 22 is shown, and the other members are not shown. In FIG. 9, a plurality of exposed portions A5 are formed on the surfaces of the reinforcing core material 22 arranged along the vertical direction and the reinforcing core material 22 arranged along the horizontal direction. here,
The sum of the projected areas of the exposed portion A5 in the state viewed from above is S1, and the sum of the projected areas of the reinforcing core member 22 is S2. Then, although the exposed area ratio is expressed by S1 / S2, the expression (II) can be derived by using the expression (I) as shown below.
The exposed area ratio = S1 / S2.
Here, given the above formula (I),
S2 = C = A−B = A (1−B / A) = A (1−aperture ratio)
Exposure area ratio = S1 / (A (1-opening ratio)) (II)
It becomes.
S1: Total sum of projected areas of exposed portion A5 S2: Total sum of projected areas of reinforced core material 22 A: Reinforced core material 22 arranged in the vertical direction and reinforced core material 12 arranged in the horizontal direction (2
2) Projected area of ion exchange membrane including (see FIG. 7)
B: Total area (B) of the region through which substances such as ions can pass (see FIG. 7)
C: Total area of the reinforcing core material 22

As shown in FIG. 8, in the ion exchange membrane 2 of the present embodiment, a convex portion 21 having a height of 20 μm or more is formed on the surface of the membrane main body 20 in which the opening portion 202 is formed in a sectional view. ing. In the present embodiment, when the vertical direction with respect to the surface of the membrane body 20 is the height direction (see, for example, the arrows α and β in FIG. 8), the convex portion 21 is formed on the surface having the opening 202.
It is preferable to have. In particular, since the first layer (sulfonic acid layer) 20a has the opening portion 202 and the convex portion 21, the electrolytic solution is sufficiently supplied to the membrane body 20 during electrolysis, so that the influence of impurities is exerted. It can be further reduced. Moreover, it is more preferable that the opening part 202, the exposed part, and the convex part 21 are formed on the surface of the layer containing the fluorinated polymer having a sulfonic acid group. Usually, the ion exchange membrane is used in close contact with the anode for the purpose of lowering the electrolysis voltage. However, when the ion exchange membrane and the anode are in close contact with each other, it tends to be difficult to supply an electrolytic solution (an anolyte such as salt water). Then, since the convex part is formed on the surface of the ion exchange membrane, adhesion between the ion exchange membrane and the anode can be suppressed, so that the electrolyte solution can be supplied smoothly. As a result, accumulation of metal ions and other impurities in the ion exchange membrane can be prevented, the concentration of chloride ions in the resulting alkali hydroxide can be reduced, and damage to the cathode surface of the membrane can be suppressed.

(Coating layer)
The ion exchange membrane of this embodiment further has a coating layer that covers at least a part of at least one surface of the membrane body from the viewpoint of preventing gas from adhering to the cathode side surface and the anode side surface during electrolysis. Is preferred. FIG. 10 is a schematic cross-sectional view of a third embodiment of the ion exchange membrane of the present embodiment. The ion exchange membrane 3 includes a first layer 30a that is a sulfonic acid layer,
A membrane body 30 having a second layer 30b, which is a carboxylic acid layer laminated on the first layer 30a, and a reinforcing core member 32 disposed inside the membrane body 30; A plurality of convex portions 31 are formed on the surface of one layer side (see arrow α), and a plurality of apertures 302 are formed,
In addition, a communication hole 304 that communicates at least two opening portions 302 is formed inside the membrane body 30. Furthermore, the surface of the membrane body 30 on the first layer side (see arrow α) is covered with the coating layer 34a, and the surface of the membrane body 30 on the second layer side (see arrow β) is covered with the coating layer 34b. Yes. That is, the ion exchange membrane 3 is obtained by coating the membrane body surface of the ion exchange membrane 1 shown in FIG. 1 with a coating layer. Such a coating layer 34a,
By covering the surface of the membrane body 30 with 34b, it is possible to prevent gas generated during electrolysis from adhering to the membrane surface. Thereby, since the membrane permeability of a cation can be improved further, it exists in the tendency for an electrolysis voltage to be reduced further.

The coating layer 34a may completely cover the convex portion 31 and the opening portion 302,
The convex portion 31 and the opening portion 302 may not be completely covered. In other words, the convex portion 31 opening 302 may be visible from the surface of the coating layer 34a.

Although it does not specifically limit as a material which comprises the coating layers 34a and 34b, From a viewpoint of gas adhesion prevention, it is preferable that an inorganic substance is included. Examples of inorganic substances include, but are not limited to, zirconium oxide and titanium oxide. Coating layer 34a, 3
The method for forming 4b on the surface of the membrane body 30 is not particularly limited, and a known method can be used. For example, there is a method (spray method) in which a liquid in which fine particles of inorganic oxide are dispersed in a binder polymer solution is applied by spraying or the like. Examples of the binder polymer include, but are not limited to, vinyl compounds having a functional group that can be converted into a sulfone-type ion exchange group. The application conditions are not particularly limited, and for example, 6
A spray can be used at 0 ° C. Examples of methods other than the spray method include, but are not limited to, a roll coat and the like.

The coating layer 34a is laminated on the surface of the first layer 30a which is a layer containing a fluorinated polymer having a sulfonic acid group (sulfonic acid layer).
It is only necessary that 02 be perforated on the surface of the membrane main body 30, and it is not always necessary to perforate on the surface of the first layer 30a.

The coating layers 34 a and 34 b may be any one that covers at least one surface of the membrane body 30. Therefore, for example, the coating layer 34a may be provided only on the surface of the first layer 30a, or the coating layer 34b may be provided only on the surface of the second layer 30b. In the present embodiment, it is preferable that both surfaces of the membrane body 30 are covered with the coating layers 34a and 34b from the viewpoint of preventing gas adhesion.

The coating layers 34a and 34b may be any coating that covers at least a part of the surface of the membrane main body 30 and may not necessarily cover all of the surface. It is preferable that the entire surface is covered with the coating layers 34a and 34b.

The average thickness of the coating layers 34a and 34b is preferably 1 to 10 μm from the viewpoint of preventing gas adhesion and increasing the electrical resistance due to the thickness.

The ion exchange membrane 3 is formed by coating the surface of the ion exchange membrane 1 shown in FIG. 1 with coating layers 34a and 34b.
For members and configurations other than the coating layers 34a and 34b,
The members and configurations already described as the ion exchange membrane 1 can be similarly employed.

FIG. 11 is a schematic cross-sectional view of a fourth embodiment of the ion exchange membrane of the present embodiment. The ion exchange membrane 4 includes a membrane body 40 having a first layer 40a that is a sulfonic acid layer, and a second layer 40b that is a carboxylic acid layer laminated on the first layer 40a, and an interior of the membrane body 40. A plurality of convex portions 41 are formed on the surface of the membrane body 40 on the first layer side (see arrow α), and a plurality of apertures 402 are formed. In addition, a communication hole 404 that connects at least two apertures 402 to each other is formed inside the membrane body 40, and the reinforcing core member 42 is formed on the surface of the membrane body 40 where the apertures 402 are formed. An exposed portion A5 that is partially exposed is formed. Further, the surface of the membrane body 40 on the first layer side (see arrow α) is covered with the coating layer 44a, and the surface of the membrane body 40 on the second layer side (see arrow β) is covered with the coating layer 44b. Yes. That is, the ion exchange membrane 4 is obtained by coating the membrane body surface of the ion exchange membrane 2 shown in FIG. 8 with a coating layer. By covering the surface of the membrane body 40 with the coating layers 44a and 44b, it is possible to prevent the gas generated during electrolysis from adhering to the membrane surface. Thereby, since the membrane permeability of a cation can be improved further, it exists in the tendency for an electrolysis voltage to be reduced further.

The exposed portion A5 only needs to expose the reinforcing core material 42 at least on the surface of the membrane body 40, and does not need to be exposed to the surface of the coating layer 44a.

The ion exchange membrane 4 is formed by coating the surface of the ion exchange membrane 2 shown in FIG.
For members and configurations other than the coating layers 44a and 44b,
The members and configurations already described as the ion exchange membrane 2 can be similarly employed. And about the coating layers 44a and 44b, the member and structure demonstrated as the coating layers 34a and 34b used with the ion exchange membrane 3 shown in FIG. 10 are employable similarly.

[Ion exchange capacity]
The ion exchange capacity of the fluoropolymer refers to the equivalent of exchange groups per gram of dry resin.
It can be measured by neutralization titration or infrared spectroscopic analysis, and when measured by infrared spectroscopic analysis, it can be measured by the method described in Examples described later. In the present embodiment, the value obtained by measuring the fluoropolymer used (before hydrolysis) by infrared spectroscopy may be used as the ion exchange capacity, or neutralized after hydrolysis. A value obtained by measurement by a titration method may be used as the ion exchange capacity. The ion exchange capacity of layer A is preferably 1.18 to 0.98 meq / g, more preferably 1.10 to 0.90 meq / g. The ion exchange capacity of layer B is 0.98 meq / g to 0.87 meq / g, 0
. It is preferably 95 to 0.87 meq / g, 0.91 to 0.87 meq / g.
It is more preferable that In addition, in this embodiment, when the layer A and / or the layer B are comprised by several layers, each layer shall satisfy | fill the above-mentioned ion exchange capacity.

In addition, since the ion exchange capacity is one of the factors that control the current-carrying surface C damage, if the ion-exchange capacity is out of the above range, the electrolysis performance is deteriorated or the current-carrying surface C is damaged in electrolysis. Absent. The ion exchange capacity of layer B is 0.87 meq / g to 0.00.
As the value increases in the range of 98 meq / g, the resistance to current-carrying surface C damage tends to improve. The ion exchange capacity of the layer A and the ion exchange capacity of the layer B can be controlled within the above-described ranges by adopting preferable manufacturing conditions described later, for example. Specifically, the ion exchange capacity of each layer can be controlled by, for example, selection of a monomer constituting the fluoropolymer contained in the layer and the content of the monomer. Specifically, for example, the aforementioned general formula (1)
To (3), and more specifically, the general formula (2) containing an ion exchange group
) And (3), the ion exchange capacity tends to increase as the content of the monomer increases.

[Electrolysis tank]
The ion exchange membrane of this embodiment can be used for various electrolytic cells. The electrolytic cell 13 includes an anode 11, a cathode 12, and an ion exchange membrane of the present embodiment disposed between the anode and the cathode.
At least. Although an electrolytic cell can be used for various electrolysis, the case where it is used for electrolysis of aqueous alkali chloride solution is demonstrated as a typical example below.

Electrolysis conditions are not particularly limited, and can be performed under known conditions. For example, in the anode chamber
5 to 5.5 N (N) alkali chloride aqueous solution is supplied, the cathode chamber is supplied with water or diluted alkali hydroxide aqueous solution, the electrolysis temperature is 50 to 120 ° C., and the current density is 5 to 100 A / dm ² . Electrolysis can be performed under conditions.

The configuration of the electrolytic cell according to this embodiment is not particularly limited, and may be, for example, a monopolar type or a bipolar type. The material constituting the electrolytic cell is not particularly limited. For example, the material for the anode chamber is preferably titanium or the like resistant to alkali chloride and chlorine, and the material for the cathode chamber is resistant to alkali hydroxide and hydrogen. Nickel or the like is preferred. The electrodes may be arranged with an appropriate interval between the ion exchange membrane and the anode, but even if the anode and the ion exchange membrane are arranged in contact with each other, they can be used without any problem. Further, the cathode is generally arranged with an appropriate distance from the ion exchange membrane, but even a contact type electrolytic cell (zero gap type electrolytic cell) without this distance can be used without any problems. .

Furthermore, since the electrolytic cell according to the present embodiment includes an ion exchange membrane that is particularly resistant to damage to the cathode surface (carboxylic acid layer), ODC (ODC: Oxygen Depolari).
(Zed Cathode) electrolysis can also be suitably applied.

[Method for producing ion exchange membrane]
As a suitable manufacturing method of the ion exchange membrane which concerns on this embodiment, the method which has the process of the following (1)-(6) is mentioned;
(1) a step of producing a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis;
(2) The sacrificial yarn is arranged between adjacent reinforcing core materials by weaving at least a plurality of reinforcing core materials and a sacrificial yarn having a property of dissolving in acid or alkali and forming a communication hole. Obtaining a reinforcing material,
(3) a step of obtaining a film by forming a film of the fluorinated polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis;
(4) A step of embedding the reinforcing material in the film to obtain a membrane body in which the reinforcing material is disposed;
(5) A step of forming a communication hole in the membrane body by obtaining an ion exchange group by hydrolyzing an ion exchange group precursor of a fluoropolymer with an acid or an alkali and dissolving the sacrificial yarn (Hydrolysis step),
(6) A step of forming the opening portion on the film surface of the film body by polishing the film surface.

According to the above method, the film main body on which a desired convex portion is formed can be obtained by controlling processing conditions such as temperature, pressure, time and the like at the time of embedding in the step (4). In step (5), the sacrificial yarn disposed inside the membrane main body is eluted to form a communication hole in the membrane main body. In step (6), an opening is formed on the membrane surface. Thus, an ion exchange membrane can be obtained. Hereinafter, each process will be described in more detail.

(1) Step: Production of fluorinated polymer In the present embodiment, the fluorinated polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis is as described above. It is obtained by appropriately polymerizing the monomer. In order to control the ion exchange capacity of the fluorine-containing polymer, as described above, the mixing ratio of the raw material monomers may be adjusted in the production process.

(2) Step: Step of obtaining a reinforcing material In the present embodiment, the reinforcing material is composed of a reinforcing core material and a sacrificial yarn, and is not limited to the following. For example, woven fabric. When the reinforcing material is embedded in the film, the reinforcing yarn forms a reinforcing core material, and the sacrificial yarn elutes in the step (5) described later to form a communication hole. The blended amount of the sacrificial yarn is preferably 10 to 10% of the entire reinforcing material.
It is 80 mass%, More preferably, it is 30-70 mass%. Or the polyvinyl alcohol etc. which have a thickness of 20-50 denier and consist of a monofilament or a multifilament are also preferable.

In the step (2), the hole area ratio, the exposed area ratio, the hole density, the arrangement of the communication holes, and the like can be controlled by adjusting the shape and arrangement of the reinforcing core material and the sacrificial yarn. For example, when the thickness of the sacrificial yarn is increased, the sacrificial yarn is likely to be positioned near the surface of the membrane body in the step (4) described later, and the sacrificial yarn is eluted in the step (5) described later. By polishing the surface, an opening is easily formed.
Also, the hole density can be controlled by controlling the number of sacrificial yarns. Similarly, when the thickness of the reinforcing yarn is increased, the reinforcing yarn is likely to come out from the surface of the membrane body in the step (6) described later, and an exposed portion is easily formed.
Furthermore, the aperture ratio of the reinforcing core material described above can be controlled by adjusting the thickness and mesh of the reinforcing core material, for example. That is, when the reinforcing core material is thickened, the aperture ratio tends to decrease, and when it is thinned, the aperture ratio tends to increase. Further, when the mesh is increased, the aperture ratio tends to decrease, and when the mesh is decreased, the aperture ratio tends to increase. From the viewpoint of further improving the electrolytic performance, it is preferable to increase the aperture ratio as described above, and from the viewpoint of ensuring strength, it is preferable to decrease the aperture ratio.

(3) Process: Film forming process In the (3) process, the fluorine-containing polymer obtained in the (1) process is formed into a film using an extruder. As described above, the film may have a two-layer structure of a sulfonic acid layer and a carboxylic acid layer, or may have a multilayer structure of three or more layers. Although it does not specifically limit as a method to form a film, For example, the following are mentioned.
-A method in which the fluorine-containing polymer constituting each layer is formed into a film separately.
A method in which a fluorine-containing polymer constituting two layers of a carboxylic acid layer and a sulfonic acid layer is coextruded to form a composite film, and the fluorine-containing polymer constituting the other sulfonic acid layer is separately formed into a film.
Note that co-extrusion is preferable because it contributes to increasing the adhesive strength at the interface.

(4) Step: Step of obtaining the membrane body In the step (4), in the step (2), the reinforcing material obtained in the step (2) is embedded in the film obtained in the step (3), so that the membrane body in which the reinforcing material is present is obtained. obtain.
The embedding method is not limited to the following, but for example, a heat-resistant release paper having air permeability on a flat plate or drum having a heating source and / or a vacuum source inside and having many pores on the surface. And a method of laminating the reinforcing material and the film in this order and integrating them while removing air between the layers by reducing the pressure at a temperature at which the fluorine-containing polymer of the film melts.

The method of embedding in the case of a three-layer structure of two sulfonic acid layers and a carboxylic acid layer is not limited to the following. For example, a release paper on a drum, a film constituting the sulfonic acid layer,
A method of laminating and integrating a reinforcing material, a film constituting a sulfonic acid layer, and a film constituting a carboxylic acid layer, or a release paper, a film constituting the sulfonic acid layer, a reinforcing material, and reinforcing the sulfonic acid layer The method of laminating | stacking and integrating in order of the composite film toward the material side is mentioned.

The method of embedding in the case of a composite film having a multilayer structure of three or more layers is not limited to the following. For example, a release paper, a plurality of films constituting each layer, a reinforcing material, and each layer are formed on a drum. A method of laminating and integrating a plurality of films in order. 3
In the case of a multi-layer structure having more than one layer, the film constituting the carboxylic acid layer is laminated at the position farthest from the drum, and the film constituting the sulfonic acid layer is adjusted to be laminated at a position close to the drum. It is preferable.

The method of integrating under reduced pressure tends to increase the thickness of the third layer on the reinforcing material, as compared with the pressure press method. In addition, the variation of the lamination | stacking demonstrated here is an example, it considers the layer structure of a desired film | membrane main body, a physical property, etc., and after selecting a suitable lamination pattern (for example, combination of each layer etc.), it is a coextrusion. can do.

For the purpose of further improving the electrical performance of the ion exchange membrane according to this embodiment, a layer containing both a carboxylic acid ester functional group and a sulfonyl fluoride functional group is provided between the sulfonic acid layer and the carboxylic acid layer. It is also possible to intervene or use a layer containing both carboxylic acid ester functional groups and sulfonyl fluoride functional groups.
As a method for producing a fluorine-containing polymer for forming this layer, a polymer containing a carboxylic acid ester functional group and a polymer containing a sulfonyl fluoride functional group are separately produced and then mixed. Alternatively, a method using a copolymer of both a monomer containing a carboxylic acid ester functional group and a monomer containing a sulfonyl fluoride functional group may be used.

(5) Step: Step of hydrolyzing In step (5), the sacrificial yarn contained in the membrane body is dissolved and removed with an acid or alkali to form a communication hole in the membrane body. Since the sacrificial yarn is soluble in acid or alkali in the ion exchange membrane manufacturing process or electrolysis environment, the sacrificial yarn is eluted from the membrane body by the acid or alkali, so that the hole is communicated with the portion. Is formed. In this way, an ion exchange membrane having a communication hole formed in the membrane body can be obtained. The sacrificial yarn may be left in the communication hole without being completely dissolved and removed. Further, the sacrificial yarn remaining in the communication hole when the electrolysis is performed may be dissolved and removed by the electrolytic solution.

The acid or alkali used in the step (5) is not particularly limited as long as it can dissolve the sacrificial yarn. Examples of the acid include, but are not limited to, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and fluorinated acetic acid. Examples of the alkali include, but are not limited to, potassium hydroxide and sodium hydroxide.

Here, the step of forming the communication hole by eluting the sacrificial yarn will be described in more detail. FIG. 12 is a schematic diagram for explaining a method of forming the communication hole of the ion exchange membrane in the present embodiment. In FIG. 12, only the reinforcing core member 52 and the sacrificial yarn 504a (the communication hole 504 formed thereby) are shown, and the other members such as the membrane body are not shown. First, the reinforcing core material 52 and the sacrificial yarn 504 a are woven into the reinforcing material 5. Then, the communication hole 504 is formed by the elution of the sacrificial yarn 504a in the step (5).

According to the above method, the reinforcing core member 52 and the sacrificial yarn 504 are arranged depending on the arrangement of the reinforcing core member 52, the communication hole 504, and the opening (not shown) inside the membrane body of the ion exchange membrane.
Since it is only necessary to adjust the method of weaving a, it is simple. FIG. 12 illustrates the plain weave reinforcing material 5 in which the reinforcing core material 52 and the sacrificial yarn 504a are knitted along both the vertical direction and the horizontal direction on the paper surface. The arrangement of the core material 52 and the sacrificial yarn 504a can be changed.
In step (5), the membrane body obtained in step (4) described above can be hydrolyzed to introduce ion exchange groups into the ion exchange group precursor.

(6) In the method in which the sacrificial core material and the reinforcing core material are exposed on the surface of the ion exchange membrane by polishing in the process, only the polymer on the communication hole having poor wear resistance is selectively removed, thereby exposing the reinforcing core material. The hole portion can be formed efficiently without greatly increasing the area ratio. According to the manufacturing method of the ion exchange membrane which concerns on this embodiment, the hole area ratio of an opening part can be made high, and the exposed area ratio of an exposed part can be made low. The polishing method is not limited to the following, for example, a method in which the polishing roller is brought into contact with the traveling film and the polishing roller is rotated at a speed faster than the traveling speed of the film or in a direction opposite to the traveling direction of the film. It is done. At this time, the larger the relative speed between the polishing roller and the film, the larger the holding angle of the polishing roller, and the higher the running tension, the higher the opening area ratio of the opening portion, the higher the exposed area ratio of the exposed portion. Therefore, the relative speed between the polishing roller and the film is preferably 50 m / h to 1000 m / h.

Moreover, in the ion exchange membrane which concerns on this embodiment, it does not specifically limit as a method of forming a convex part on the surface of a film | membrane main body, The well-known method of forming a convex part on the resin surface can also be employ | adopted. In the present embodiment, as a method for forming the convex portion on the surface of the film main body, specifically, a method for embossing the surface of the film main body can be mentioned. For example, when the above-described film and the reinforcing material are integrated, the above-described convex portion can be formed by using a release paper that has been embossed in advance.

According to the method for producing an ion exchange membrane according to the present embodiment, the opening and the exposed portion are formed by polishing in a wet state after hydrolysis, so that the polymer of the membrane body has sufficient flexibility. Therefore, the convex shape does not fall off. When forming a convex part by embossing, control of the height and arrangement density of a convex part can be performed by controlling the emboss shape (shape of release paper) to transfer.

After the steps (1) to (6) described above, the coating layer described above may be formed on the surface of the obtained ion exchange membrane.

Hereinafter, the present embodiment will be described in detail by way of examples. Note that the present embodiment is not limited to the following examples.

[Evaluation method and measurement method for current-carrying C damage]
Electrolysis in the examples and comparative examples was performed using an extended metal cathode / aperture plate anode (4 mmΦ ×
In a 1 dm ² self-circulating electrolysis cell with 6 pitches and an open area ratio of 40%), the sodium chloride aqueous solution containing almost no impurities is supplied to the anode side while being adjusted, and the caustic soda concentration on the cathode side is 32% by mass. At a current density of 60 A / dm ² and a temperature of 90 ° C.
The differential pressure between the liquid pressure on the cathode side of the electrolytic cell and the liquid pressure on the anode side was carried out for 7 days under the condition that the liquid pressure on the cathode side was increased by 8.8 kpa. The cathode was a nickel base coated with nickel oxide as a catalyst, and the anode was a titanium base coated with ruthenium oxide, iridium oxide and titanium oxide as a catalyst.
After the electrolysis, the current-carrying surface (carboxylic acid layer) of the ion exchange membrane from which the coating layer had been removed was photographed with a commercially available camera to obtain an image. In this image, mark the damaged part of the current-carrying surface,
Using \ USB Digital Scale 1.1J (manufactured by SCARA) as analysis software, the damaged area ratio (%) was calculated as damaged area / undamaged area × 100.

Moreover, the following evaluation was performed supposing the application to the ODC electrolysis of an ion exchange membrane. The evaluation method is
In a 1 dm ² self-circulating electrolysis cell of ODC cathode / perforated plate anode (4 mmΦ x 6 pitch, open area ratio 40%), the sodium chloride aqueous solution was supplied to the anode side while being adjusted to 195 g / liter, and the caustic soda concentration on the cathode side At a current density of 30 A / dm ² and a temperature of 8
The temperature was set at 8 ° C. for 7 days.
After the electrolysis, the damaged portion of the current-carrying surface (carboxylic acid layer) of the ion exchange membrane from which the coating layer has been removed is marked, and as an analysis software, ¥ USB Digital Scale 1.1J
(Scalar Co., Ltd.) was used, and the damaged area ratio (%) was calculated by the area of damaged portion / area of undamaged portion × 100.

[Salt water supply hole measurement method]
The area ratio of the salt water supply holes was measured by image analysis of a microscopic image of the surface of the ion exchange membrane. First, the membrane body surface of the ion exchange membrane after hydrolysis was cut out to a size of 2 mm in length and 3 mm in width to prepare a sample. The sample cut out is 0.1 g of crystal violet dye.
Was immersed in a solution obtained by dissolving 100 mL of water in a mixed solvent of 500 mL of ethanol, and the sample was stained. Using a microscope (manufactured by OLYMPUS), the surface state of the dyed sample was confirmed at a magnification of 20 times. Nine materials were cut out from the surface of one ion-exchange membrane, and the average value was evaluated (N = 9).

A white area not dyed corresponds to an exposed portion of the salt water supply hole or the reinforcing core material. Whether it corresponds to a salt water supply hole or an exposed part was judged by the positional relationship between the reinforcing core material in the ion exchange membrane and the communication hole. In addition, when it is unclear whether it corresponds to the salt water supply hole or the exposed portion, the range observed with the microscope is observed with a scanning electron microscope (SEM), and the SE at that time
Judgment was made based on M photographs. That is, according to the SEM photograph, when the white region not dyed was indented from the surface of the membrane body, it was judged as a salt water supply hole, and when it came out from the surface of the membrane body, it was judged as an exposed portion.

In the salt water supply hole and the exposed part, when the communication hole crosses, the part may be dyed with a dye, and a white part not dyed may be observed in a divided state. In that case, the salt water supply hole and the exposed part were not divided by the communication hole or the like, and the white region not dyed with the dye was identified as being continuous. When the ion exchange membrane had a coating layer, measurement was performed after removing only the coating using a soft brush with a mixed solution of water and ethanol.

Regarding the area ratio of the salt water supply hole, first, obtain the total area (salt water supply hole area B) of the white portion corresponding to the salt water supply hole of the sample and divide by the surface area of the sample (2 mm × 3 mm = 6 mm ² ). Determined by In addition, the area ratio of the salt water supply hole was an average value of the results observed at nine locations on the ion exchange membrane (N = 9).

[Measurement method of height and arrangement density of convex parts]
The height and arrangement density of the convex portions were confirmed by the following method. First, the ion exchange membrane 100
On the film surface in the range of 0 μm square, the lowest point was used as a reference. A portion having a height of 20 μm or more from the reference point was defined as a convex portion. At that time, as a method of measuring the height, KEYE
This was performed using a “color 3D laser microscope (VK-9710)” manufactured by NCE. Specifically, a 10 cm × 10 cm portion is arbitrarily cut out from the dried ion exchange membrane, the smooth plate and the cathode side of the ion exchange membrane are fixed with double-sided tape, and the anode side of the ion exchange membrane is used as a measurement lens. It was set on the measurement stage to face. 1000 μm in each 10 cm × 10 cm film
The shape on the surface of the ion exchange membrane was observed in the measurement area of m square, and the convex portion was confirmed by measuring the height from the lowest point as a reference. As above, the height is 20
Table 1 shows the convex structure “existing” when the convex part having a size of μm or more was confirmed, and the convex structure “none” when the convex part was not confirmed. Moreover, about the arrangement | positioning density of a convex part, from the ion-exchange membrane, arbitrarily cut out three 10 cm × 10 cm membranes and averaged the values measured at 9 locations in a 1000 μm square measurement range for each 10 cm × 10 cm membrane. And asked.
In addition, about the area of the convex part, it confirmed as follows. That is, the surface of the film obtained in the embedding process (OLYMPUS SZX10) was observed, and an image was acquired. In this image, the convex part is marked, and the USB Digital Scale 1 is used as analysis software.
. 1J (manufactured by SCARA) was used to calculate the convex area / the area other than the convex area.

[Measurement method of thickness of each layer]
The width of the ion exchange membrane after the hydrolysis step is about 100 in the cross-sectional direction from the layer A-1 side or the layer B side.
The thickness was measured using an optical microscope with the cross section turned to the top in a state of being cut off at μm and containing water. At that time, the part to be cut off is an intermediate part (valley part) of the adjacent reinforcing core material, and the location to be measured in the obtained cross-sectional view is the intermediate part of the adjacent reinforcing core material 12 as shown in FIG.
The thicknesses of layer A and layer B were measured with the direction from (α) to (β) as the thickness direction.

[Measurement of sodium chloride concentration in sodium hydroxide]
The electrolytic cell used for electrolysis has a structure in which a cation exchange membrane is disposed between an anode and a cathode, and four electrolytic cells of forced circulation type (forced circulation type) are arranged in series. A thing was used. The distance between the anode and the cathode in the electrolysis cell was 1.5 mm. As cathode
An electrode obtained by applying nickel oxide as a catalyst to nickel expanded metal was used.
As the anode, an electrode obtained by applying ruthenium oxide, iridium oxide and titanium oxide as a catalyst to an expanded metal of titanium was used. Using the electrolytic cell, the concentration of sodium chloride contained in the produced caustic soda was measured. That is, salt water was supplied to the anode side while adjusting the concentration to 205 g / L, and water was supplied while maintaining the caustic soda concentration on the cathode side at 32% by mass. The temperature of the salt water was set to 90 ° C., and electrolysis was performed at a current density of 4 kA / m ² , with the liquid pressure on the cathode side of the electrolytic cell being 5.3 kPa higher than the liquid pressure on the anode side. The concentration of sodium chloride contained in caustic soda obtained by performing electrolysis for 7 days was measured according to the method of JIS K 1200-3-1. That is, nitric acid is added to sodium hydroxide produced by electrolysis and neutralized to obtain a neutralized solution. The neutralized solution is mixed with an iron (III) sulfate ammonium solution and mercury thiocyanate (
II) was added and the solution was colored. The caustic soda generated during the electrolysis operation overflowed from the cell discharge pipe and flowed out of the cell, and was recovered. U solution
The sodium chloride concentration in caustic soda is measured every other day by spectrophotometric analysis with a V meter,
The average value for 7 days was determined as the sodium chloride concentration.

[Current efficiency measurement]
The operation was performed under the same conditions using the electrolytic cell. That is, salt water was supplied to the anode side while adjusting the concentration to 205 g / L, and water was supplied while maintaining the caustic soda concentration on the cathode side at 32% by mass. The temperature of the salt water was set to 90 ° C., and electrolysis was performed at a current density of 4 kA / m ² , with the liquid pressure on the cathode side of the electrolytic cell being 5.3 kPa higher than the liquid pressure on the anode side. The current efficiency was measured by measuring the mass and concentration of the produced caustic soda and dividing the number of moles of caustic soda produced in a certain time by the number of moles of current flowing during that time.

[Electrolytic voltage measurement]
The operation was performed under the same conditions using the electrolytic cell. That is, salt water was supplied to the anode side while adjusting the concentration to 205 g / L, and water was supplied while maintaining the caustic soda concentration on the cathode side at 32% by mass. The temperature of the salt water was set to 90 ° C., and electrolysis was performed at a current density of 4 kA / m ² , with the liquid pressure on the cathode side of the electrolytic cell being 5.3 kPa higher than the liquid pressure on the anode side. Further, the voltage between the positive and negative electrodes in the electrolytic cell was measured daily with a KEYENCE voltmeter TR-V1000, and 7
The average value for the day was determined as the electrolysis voltage.

[Measurement of ion exchange capacity]
As the fluorine-containing polymer having an ion-exchange group, each of the fluorine-containing polymers A-1 described later,
About 1 g of each of the fluorinated polymer A-2 and the fluorinated polymer B was used, and press molding was performed at a temperature about 30 ° C. higher than the pseudo melting point value of each polymer to obtain a film corresponding to each polymer. The obtained film was measured with a transmission infrared spectroscopic analyzer (FTIR-4200 manufactured by JASCO Corporation). From the height of each infrared peak of CF ₂ , CF, CH ₃ , OH, SO ₂ F of the obtained infrared peak, the ratio of the structural unit having a group that can be converted into a carboxylic acid functional group or a sulfonic acid functional group was calculated. . These are the proportions of structural units having a carboxylic acid functional group and a sulfonic acid functional group of the polymer obtained by hydrolyzing the fluoropolymer, and a sample having a known ion exchange capacity calculated by the titration method is used as a calibration curve. The ion exchange capacity was determined.

[Example 1]
As the fluoropolymer A-1, a monomer represented by the following general formula (1) and the following general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.
CF ₂ = CX ₁ X ₂ (1)
(In the general formula (1), X ₁ and X ₂ each independently represent F, Cl, H or CF ₃ .
)
_{CF 2 = CFO- (CF 2 YFO} ) a - (CF 2) b -SO 2 F ··· (2)
(In General Formula (2), a is an integer of 0 to 2, b is an integer of 1 to 4, Y is F or CF ₃ , R
Represents CH ₃ , C ₂ H ₅ or C ₃ H ₇ . )

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the following general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.
_{CF 2 = CF (OCF 2 CYF} ) c -O (CF 2) d -COOR ··· (3)
(In General Formula (3), c represents an integer of 0 to 2, d represents an integer of 1 to 4, Y represents F or CF ₃ , and R represents CH ₃ , C ₂ H _5, or C ₃ H ₇ . Represents.)

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers having a thickness of 104 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of layer A-2 was 79 μm, and the thickness of layer B was 25 μm. Also, a layer A having a thickness of 20 μm using a single-layer T die.
-1 monolayer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The salt water supply porosity of the composite membrane was 2.5%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. The current efficiency = 97.1 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.91V and good. Further, the damage area ratio was as good as 10%.
Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was hardly damaged and was satisfactory.

[Example 2]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers having a thickness of 104 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of layer A-2 was 74 μm, and the thickness of layer B was 30 μm. Also, a layer A having a thickness of 20 μm using a single-layer T die.
-1 monolayer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The brine feed porosity of the composite membrane was 2.3%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. The current efficiency = 97.2 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.95V and good. Further, the damage area ratio was 12%, which was favorable.
Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was hardly damaged and was satisfactory.

[Example 3]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded with two extruders, two-layer co-extrusion T-die, and a take-out machine, and two layers having a thickness of 89 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of layer A-2 was 74 μm, and the thickness of layer B was 15 μm. Also, a layer A- having a thickness of 20 μm using a single layer T die
1 single-layer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The brine feed porosity of the composite membrane was 2.3%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. Note that current efficiency = 96.9 at a catholyte concentration of 32 mass%.
%, Electrolysis voltage = 2.86V. Further, the damage area ratio was good at 13%.
Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was hardly damaged and was satisfactory.

[Example 4]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at 6.8: 1, and ion exchange is performed. Capacity is 0.98m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers with a thickness of 99 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of the layer A-2 was 74 μm, and the thickness of the layer B was 25 μm. Also, a layer A- having a thickness of 20 μm using a single layer T die
1 single-layer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The salt water supply porosity of the composite membrane was 2.2%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. The current efficiency = 96.4 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.86V. Further, the damage area ratio was 7%, which was favorable. Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was hardly damaged and was satisfactory.

[Example 5]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 4.6: 1 to obtain a polymer having an ion exchange capacity of 1.14 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers with a thickness of 99 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of the layer A-2 was 74 μm, and the thickness of the layer B was 25 μm. Also, a layer A- having a thickness of 20 μm using a single layer T die
1 single-layer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The salt water supply porosity of the composite membrane was 3.3%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. Note that the current efficiency = 97.5 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.96V. Further, the damage area ratio was 12%, which was favorable.
Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was hardly damaged and was satisfactory.

[Comparative Example 1]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 6: 1 to obtain a polymer having an ion exchange capacity of 0.95 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers with a thickness of 99 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of the layer A-2 was 74 μm, and the thickness of the layer B was 25 μm. Also, a layer A- having a thickness of 20 μm using a single layer T die
1 single-layer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane. Further, as a result of observing the surface of the obtained film, the film (b) on the anode surface side had 250 protruding portions made of only a polymer having a hemispherical ion exchange group having an average height of 60 μm / cm ² , and the total area of the convex portions is 0.00 per cm ² .
The formation of 2 cm ² was confirmed. In this example, since the polishing process after hydrolysis was not performed, the salt water supply hole was not formed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. The salt water supply porosity of the composite membrane was 0%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. The current efficiency = 97.0 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.94V. On the other hand, the damage area ratio was 24%, which was inferior to the value of the example. Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was severely damaged, resulting in inferior results to the examples.

[Comparative Example 2]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 5.4: 1 to obtain a polymer having an ion exchange capacity of 0.98 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at 6: 1 to obtain a polymer having an ion exchange capacity of 0.95 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers with a thickness of 99 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of the layer A-2 was 74 μm, and the thickness of the layer B was 25 μm. Also, a layer A- having a thickness of 20 μm using a single layer T die
1 single-layer film (b) was obtained.

A heat-resistant release paper, a single layer film (b), a reinforced core material, and a two-layer film (a) that are permeable to air on a drum having a heating source and a vacuum source inside, and a large number of fine holes on the surface. Laminated to 2
Integrating while excluding air between each material at a temperature of 30 ° C. and a reduced pressure of −650 mmHg,
A composite membrane was obtained. The convex structure was not formed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The brine feed porosity of the composite membrane was 3.6%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. Note that current efficiency = 96.9 at a catholyte concentration of 32 mass%.
%, Electrolysis voltage = 2.93V and good. On the other hand, the damage area ratio was 35%, which was inferior to the value of the example. Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was severely damaged, resulting in inferior results to the examples.

[Comparative Example 3]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at a ratio of 7.5: 1, and ion exchange is performed. Capacity is 0.89m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers having a thickness of 104 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of layer A-2 was 79 μm, and the thickness of layer B was 25 μm. Also, a layer A having a thickness of 20 μm using a single-layer T die.
-1 monolayer film (b) was obtained.

A heat-resistant release paper, a single layer film (b), a reinforced core material, and a two-layer film (a) that are permeable to air on a drum having a heating source and a vacuum source inside, and a large number of fine holes on the surface. Laminated to 2
Integrating while excluding air between each material at a temperature of 30 ° C and a reduced pressure of -650mmHg,
A composite membrane was obtained. The convex structure was not formed.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The salt water supply porosity of the composite membrane was 2.2%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of performing electrolysis and evaluating the physical properties of the ion exchange membrane obtained as described above. The current efficiency = 97.1% at a catholyte concentration of 32% by mass,
The electrolytic voltage was 2.92 V, which was favorable. On the other hand, the damage area ratio was 27%, which was inferior to the value of the example. Furthermore, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis,
The carboxylic acid layer was severely damaged, resulting in inferior results to the examples.

[Comparative Example 4]
As the fluoropolymer A-1, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluoropolymer A-2, the monomer represented by the general formula (1) and the general formula (2
) Was copolymerized at a ratio of 5: 1 to obtain a polymer having an ion exchange capacity of 1.05 meq / g.

As the fluorine-containing polymer B forming the layer B, the monomer represented by the general formula (1) and the monomer represented by the general formula (3) are copolymerized at 8.5: 1 to perform ion exchange. Capacity is 0.82m
An equivalent weight / g polymer was obtained.

Fluoropolymer A-2 and Fluoropolymer B were prepared and co-extruded by two extruders, two-layer co-extrusion T-die, and an apparatus equipped with a take-out machine, and two layers having a thickness of 104 μm A film (a) was obtained. As a result of observing the cross section of the film with an optical microscope, the thickness of layer A-2 was 79 μm, and the thickness of layer B was 25 μm. Also, a layer A having a thickness of 20 μm using a single-layer T die.
-1 monolayer film (b) was obtained.

Breathable heat-resistant release paper, single-layer film (b), reinforced core material, two-layer film, which has a heat source and vacuum source inside, and a drum having a large number of fine holes on the surface and embossed (A
) Were laminated in order, and were integrated while excluding air between the materials at a temperature of 230 ° C. and a reduced pressure of −650 mmHg to obtain a composite membrane.

This composite membrane was subjected to 80 ° C. in an aqueous solution containing 30% by mass of DMSO and 3.2 N (N) of KOH.
Was then hydrolyzed for 0.5 hour at a temperature of 50 ° C., followed by a salt exchange treatment using a 0.6 N (N) NaOH solution at 50 ° C. for 1 hour. Then, the running tension was 20 kg / cm, the relative speed between the polishing roll and the composite film was 100 m / min, the pressing amount of the polishing roll was 2 mm, and the surface of the composite film was polished to form an opening. The brine feed porosity of the composite membrane was 2.3%.

In a mixed solution of 50/50 parts by mass of water and ethanol, the ion exchange capacity is 1.0 meq / g
20 wt% of a fluorine-containing polymer having a sulfonic acid group obtained by hydrolyzing a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F It was. A suspension in which 40 wt% of zirconium oxide having a primary particle diameter of 1 μm was added to the solution and uniformly dispersed by a ball mill was obtained. This suspension was applied to both surfaces of the hydrolyzed ion exchange membrane by a spray method and dried to form a coating layer.

Table 1 shows the results of electrolysis as described above for the ion exchange membrane obtained as described above and the evaluation of each physical property. The current efficiency = 97.6 at a catholyte concentration of 32% by mass.
%, Electrolysis voltage = 2.98V. On the other hand, the damage area ratio = 17%, which is inferior to the value of the example. Further, in the evaluation assuming application of the ion exchange membrane to ODC electrolysis, the carboxylic acid layer was severely damaged, resulting in inferior results to the examples.

1, 2, 3, 4 ... cation exchange membrane,
5 ... Reinforcing material,
10, 20, 30, 40 ... membrane main body,
11, 21, 31, 41 ... convex portion 12, 22, 32, 42, 52 ... reinforcing core,
10a, 20a, 30a, 40a ... 1st layer (sulfonic acid layer),
10b, 20b, 30b, 40b ... second layer (carboxylic acid layer),
34a, 34b, 44a, 44b ... coating layer,
100 ... electrolytic cell,
102, 202, 302, 402 ... opening portion,
104, 204, 304, 404, 504 ... communicating holes,
106 ... hole,
200 ... Anode,
300 ... cathode,
504a ... Sacrificial yarn,
A1, A2, A3, A4 ... area,
A5 ... Exposed part

Claims (6)

A layer A containing a fluoropolymer having a sulfonic acid group;
A layer B containing a fluoropolymer having a carboxylic acid group;
Have
The layer A has a convex portion having a height of 20 μm or more on a cross-sectional view on at least one surface,
A plurality of apertures are formed on the surface of the layer A,
A ratio (aperture area ratio) of the total area of the apertures to the area of the surface of the layer A is 0.
4-15%,
The ion exchange capacity of layer A is 1.18-0.98 meq / g,
An ion exchange membrane, wherein the layer B has an ion exchange capacity of 0.98 to 0.87 meq / g. The arrangement density of the convex portions on the surface of the layer A is 20-1500 pieces / cm ² .
The ion exchange membrane according to claim 1. The thickness of the layer A is 50 to 180 μm,
The ion exchange membrane according to claim 1 or 2, wherein the layer B has a thickness of 5 to 40 µm. The layer A includes a polymer of a compound represented by CF ₂ ═CF— (OCF ₂ YF) _a —O (CF ₂ ) _b —SO ₂ F;
The layer B comprises a polymer of _{CF 2 = CF- (OCF 2 CYF} ) c -O (CF 2) a compound represented by _d -COOR,
Here, the a is an integer of 0 to 2, the c is an integer of 0 to 2, and the b and d are 1
An to 4 integer, the Y is F or CF _3, wherein R is CH _3, C ₂ H ₅ or C ₃ H _7, ion exchange according to any one of claims 1 to 3 film. The total area of the projection is a surface 1 cm ² per 0.01cm ² ~0.6cm ² of the layer A, the ion-exchange membrane according to any one of claims 1 to 4.   The ion exchange membrane according to any one of claims 1 to 5, which is used for ODC electrolysis.