Ion exchange membrane roll, method for producing ion exchange sheet, and method for producing ion exchange membrane roll

Abstract

The invention provides an ion exchange winding body with high production efficiency and a manufacturing method of an ion exchange sheet. According to one embodiment, an ion exchange membrane roll is provided. The ion exchange membrane winding body is a planar ion exchange membrane winding body in a dry state. The ion exchange membrane has a first side and a second side. The second side is orthogonal to the first side and has a length less than or equal to that of the first side. In the ion exchange membrane winding body, the ion exchange membrane is wound around a winding axis in a direction parallel to the second side. The air layer ratio of the ion exchange membrane roll is more than 5% and 50% or less.

Description

TECHNICAL FIELD

[0001] The present application relates to an ion exchange membrane roll body, a method for manufacturing an ion exchange sheet, and a method for manufacturing an ion exchange membrane roll body. BACKGROUND

[0002] An ion exchange membrane is a membrane having an ion exchange function. An ion exchange membrane is obtained, for example, by shaping an ion exchange resin into a membrane shape or by filling an ion exchange resin in the pores of a porous base material. An ion exchange membrane includes a cation exchange membrane that allows only cations to pass through and an anion exchange membrane that allows only anions to pass through. Ion exchange membranes are used in a device for producing pure water, a device for desalination treatment of seawater, a device for desalination treatment, a fuel cell, a water electrolysis device, and the like.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-177505

[0006] Patent Document 2: Japanese Patent Application Publication No. 2023-022684 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] An object of the present application is to provide an ion exchange roll body, a method for manufacturing an ion exchange sheet, and a method for manufacturing an ion exchange membrane roll body, which are high in production efficiency.

[0009] SOLUTION TO PROBLEM

[0010] In order to solve the above problem, the present inventors and others conducted intensive studies, as a result of which it was found that, in a roll body of a planar ion exchange membrane in a dry state, the above problem can be solved by setting the air layer rate of the ion exchange membrane roll body to a prescribed range, thereby completing the following application (first embodiment).

[0011] In addition, in order to solve the above problem, the present inventors and others conducted intensive studies, as a result of which it was found that, in a method for manufacturing an ion exchange membrane roll body, the above problem can be solved by transporting a dry ion exchange membrane to a roll core at a prescribed transport speed, winding the dry ion exchange membrane to the roll core at a prescribed winding tension, and, at the time of this winding, not applying pressure to the roll core or the surface of the dry ion exchange membrane wound to the roll core, thereby completing the following application (second embodiment).

[0012] [1] An ion exchange membrane roll, which is a roll obtained by winding a planar ion exchange membrane in a dry state having a first edge and a second edge in a direction parallel to the second edge as a winding axis, the second edge being orthogonal to the first edge and having a length less than or equal to that of the first edge,

[0013] The air layer ratio of the ion exchange membrane roll described above is greater than 5% and is 50% or less as represented by the following formula (I):

[0014] Air layer ratio (%) = (Aa - dL) / Aa x 100 (I)

[0015] In the above formula (I),

[0016] Aa is the average area of the cross section of the ion exchange membrane in the roll orthogonal to the direction of the winding axis,

[0017] d is the average thickness of the ion exchange membrane,

[0018] L is the length of the first edge of the ion exchange membrane.

[0019] [2] The ion exchange membrane roll according to [1], wherein the air layer ratio is 7% or more and 38% or less.

[0020] [3] The ion exchange membrane roll according to [1] or [2], wherein the hardness measured using a hardness tester (ASKER hardness tester type C) is 80 or more and 95 or less.

[0021] [4] The ion exchange membrane roll according to any one of [1] to [3], wherein the average thickness d of the ion exchange membrane is 10 pm or more and 200 pm or less.

[0022] [5] The ion exchange membrane roll according to any one of [1] to [4], wherein the ratio Br / d of the radius Br of the cross section of the ion exchange membrane roll to the average thickness d of the ion exchange membrane is 450 or more and 12,000 or less.

[0023] [6] The ion exchange membrane roll according to any one of [1] to [5], wherein the ion exchange membrane comprises a porous base material and an ion exchange resin supported on the porous base material.

[0024] [7] The ion exchange membrane roll according to [6], wherein the ion exchange resin comprises at least one ion exchange group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, and an imidazolium group.

[0025] [8] The ion exchange membrane roll body according to [6] or [7], wherein the aforementioned porous substrate comprises a polyolefin-based resin.

[0026] [9] The ion exchange membrane roll body according to any one of [1] to [8], which has a cylindrical shape.

[0027]

[10] The ion exchange membrane roll body according to any one of [1] to [9], further comprising a roll core around which the aforementioned ion exchange membrane is wound.

[0028]

[11] The ion exchange membrane roll body according to any one of [1] to

[10] , wherein a ratio Br / Cr of a radius Cr of the aforementioned roll core to a radius Br of the aforementioned cross section of the ion exchange membrane roll body is 1.1 or greater and 3.3 or less.

[0029]

[12] A method for manufacturing an ion exchange membrane roll body, which is a method for manufacturing an ion exchange membrane roll body comprising a roll core and a dry ion exchange membrane wound around the aforementioned roll core, the method comprising:

[0030] a step of transporting the aforementioned dry ion exchange membrane to the aforementioned roll core at a transport speed of 0.75 m / min or greater and 30 m / min or less; and

[0031] a step of winding the aforementioned dry ion exchange membrane around the aforementioned roll core at a winding tension of 3 N / m or greater and 100 N / m or less,

[0032] wherein the aforementioned dry ion exchange membrane is wound around the aforementioned roll core in a manner that does not apply pressure to the aforementioned roll core or a surface of the aforementioned dry ion exchange membrane wound around the aforementioned roll core.

[0033]

[13] The method for manufacturing according to

[12] , wherein the aforementioned winding tension is 5 N / m or greater and 50 N / m or less.

[0034]

[14] The method for manufacturing according to

[12] or

[13] , wherein the aforementioned transport speed is 3 m / min or greater and 30 m / min or less.

[0035]

[15] The method for manufacturing according to any one of

[12] to

[14] , wherein a ratio Br / Cr of a radius Cr of the aforementioned roll core to a radius Br of a cross section of the ion exchange membrane roll body orthogonal to a winding axis direction is 1.1 or greater and 3.3 or less.

[0036]

[16] The method for manufacturing according to any one of

[12] to

[15] , wherein the aforementioned ion exchange membrane comprises a porous substrate and an ion exchange resin supported on the aforementioned porous substrate.

[0037]

[17] The production method according to

[16] , wherein the aforementioned ion exchange resin contains at least one ion exchange group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, and an imidazolium group.

[0038]

[18] The production method according to

[16] or

[17] , wherein the aforementioned porous substrate contains a polyolefin-based resin.

[0039]

[19] The production method according to any one of

[12] to

[18] , further comprising a step of drying the ion exchange membrane in a wet state to obtain the aforementioned dried ion exchange membrane.

[0040]

[20] The production method according to

[19] , further comprising:

[0041] a step of loading a curable composition containing an ion exchange resin precursor to a porous substrate to obtain a structure;

[0042] a step of curing the aforementioned curable composition of the aforementioned structure to obtain an ion exchange membrane precursor; and

[0043] a step of introducing an ion exchange group to the aforementioned ion exchange membrane precursor to obtain the aforementioned ion exchange membrane in a wet state.

[0044]

[21] A production method of an ion exchange sheet, comprising:

[0045] a step of cutting the aforementioned ion exchange membrane that has been unwound.

[0046] Effects of the Invention

[0047] According to the present invention, there is provided a production method of an ion exchange sheet, a production method of an ion exchange membrane roll, and a production method of an ion exchange membrane roll with high production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a perspective view schematically showing an example of an ion exchange membrane.

[0049] Figure 2 is a perspective view schematically showing an example of an ion exchange membrane roll according to the embodiment.

[0050] Figure 3 is a cross-sectional view schematically showing an example of a cross section of an ion exchange membrane roll.

[0051] Figure 4is a schematic view schematically showing an example of a polymerizable composition impregnation device.

[0052] Figure 5 is a schematic view schematically showing an example of an ion exchange membrane roll body manufacturing device. DETAILED DESCRIPTION

[0053] An ion exchange membrane is sometimes manufactured in the form of a long thin film in which the length of the long side is several tens of times or more the length of the short side. An ion exchange membrane of a desired size obtained by cutting or blanking the long thin film-shaped ion exchange membrane is used in devices such as water electrolysis devices. In these devices, the ion exchange membrane can be used in a wet state in contact with a solvent containing water or in an environment in which the wet state and the dry state are repeated.

[0054] The ion exchange function of an ion exchange membrane is exerted in a wet state. In order to maintain this quality, sometimes the ion exchange membrane is kept in a wet state without becoming a dry state from when it is manufactured as a long thin film to when it is cut to a desired size or until it is installed in a device. However, in the process of cutting the long thin film-shaped ion exchange membrane to a desired size, it is sometimes desirable to use a dry ion exchange membrane compared to a wet ion exchange membrane. In addition, when transporting a long thin film-shaped ion exchange membrane, sometimes the shape of a roll in which the long thin film-shaped ion exchange membrane in a wet state is wound into a roll is taken. A dry ion exchange membrane is lighter in weight than a wet ion exchange membrane, and thus the transportation cost can be suppressed.

[0055] The ion exchange membrane roll body of the first embodiment is a roll body of planar ion exchange membranes in a dry state. The ion exchange membrane has a first side and a second side. The second side is orthogonal to the first side and has a length that is equal to or less than the length of the first side. In the ion exchange membrane roll body, the ion exchange membranes are wound with the direction parallel to the second side as the winding axis. The air layer rate of the ion exchange membrane roll body is greater than 5% and is 50% or less. The air layer rate can refer to the proportion of air between the ion exchange membranes wound in the ion exchange membrane roll body. That is, the air layer rate is the value (Aa-dL) / Aa obtained by dividing the value Aa-dL obtained by subtracting the area dL of the side of the ion exchange membrane from the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll body by the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll body. The cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll body being greater than the area dL of the side of the ion exchange membrane, that is, the air layer rate exceeding 0%, means that in the ion exchange membrane roll body, air is mixed between the ion exchange membranes. In other words, the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll body being equal to the area dL of the side of the ion exchange membrane, that is, the air layer rate being 0%, means that in the ion exchange membrane roll body, the ion exchange membranes are wound without gaps.

[0056] The manufacturing method of the ion exchange membrane roll body of the second embodiment includes a step of transporting the dry ion exchange membrane to the winding core at a transport speed of 0.75 m / min or more and 30 m / min or less, and a step of winding the dry ion exchange membrane to the winding core at a winding tension of 3 N / m or more and 100 N / m or less. At the time of the winding, the dry ion exchange membrane is wound to the winding core in a manner that no pressure is applied to the winding core or the surface of the dry ion exchange membrane wound to the winding core.

[0057] If such an ion exchange membrane roll body or a dry ion exchange membrane roll body obtained by such a method is used, an ion exchange membrane of a desired size can be efficiently manufactured. That is, in order to continuously manufacture an ion exchange membrane sheet of a desired size from a dry ion exchange membrane roll body, it is necessary to extract the ion exchange membrane located at the outermost peripheral portion of the ion exchange membrane roll body from the ion exchange membrane roll body at a constant speed while rotating the ion exchange membrane roll body, that is, it is necessary to unwind the ion exchange membrane at a constant speed. In the unwinding of the ion exchange membrane, in order not to cause the unwound ion exchange membrane to be slackened or twisted, it can be required to maintain a constant transport speed and a constant tension.

[0058] However, in the dry ion exchange membrane roll body, there is a phenomenon that the overlapped ion exchange membranes are closely adhered to each other and are difficult to be unwound, that is, blocking. It is considered that the cause of the blocking is that some kind of bonding occurs between the ion exchange groups present on the surface of the dry ion exchange membrane, or between the ion exchange groups and the resin. If the blocking occurs at the time of unwinding the ion exchange membrane, the load required for unwinding the ion exchange membrane becomes non-constant, the unwinding speed and the tension vary, and thus slackening or shaking is sometimes locally generated in the unwound ion exchange membrane. If the unwinding is performed by applying a load of the required level or more in order to eliminate the slackening, the unwound ion exchange membrane is sometimes deformed, or wrinkles are generated in the transport process. In addition, if the adhesion of the ion exchange membranes to each other in the ion exchange membrane roll body is too strong, it is sometimes impossible to peel off only the ion exchange membrane located at the outermost peripheral portion, and a crack is generated in the ion exchange membrane, or deformation is generated in the portion where the adhesion is excessively strong.

[0059] The air layer ratio of the ion exchange membrane roll body of the first embodiment is greater than 5% and 50% or less. In such an ion exchange membrane roll body, it can be said that a certain amount of air layer is provided between the wound ion exchange membranes. By making the air layer ratio greater than 5%, the adhesion of the ion exchange membranes to each other can be suppressed, and sticking is less likely to occur. On the other hand, if the air layer ratio is too high, the adhesion of the ion exchange membranes to each other is reduced, and thus slack is generated in the ion exchange membrane roll body, and it is difficult to maintain the shape thereof. In addition, in an ion exchange membrane roll body having an air layer ratio of 50% or more, a state in which a part of the ion exchange membranes protrudes on a side surface orthogonal to the winding axis direction of the ion exchange membrane roll body, that is, so-called winding deviation, is likely to occur. This is because, in the process of manufacturing the ion exchange membrane roll body, the ion exchange membranes are likely to slip due to excessive mixing of air between the ion exchange membranes, and meandering of the ion exchange membranes can occur. In addition, if the air layer ratio is too high, there is a tendency that a part of the inner layer ion exchange membranes easily protrudes to the other side surface at the time of storage or transportation of the ion exchange membrane roll body, or at the time of application of an impact to one side surface. By setting the air layer ratio to 50% or less, the shape of the ion exchange membrane roll body can be maintained, and winding deviation is less likely to occur. Therefore, if the ion exchange membrane roll body of the embodiment is used, the ion exchange membranes can be continuously unwound while the speed and the tension are maintained constant. Thus, it is possible to continuously produce ion exchange membranes of a desired shape with a high yield.

[0060] In the ion exchange membrane roll body obtained by the method of the second embodiment, it is considered that an appropriate amount of air exists between the ion exchange membranes that are stacked on each other. By the presence of the air, the adhesion of the ion exchange membranes to each other can be suppressed, and sticking is less likely to occur. In addition, according to the manufacturing method, excessive mixing of air between the ion exchange membranes can be suppressed. If manufacturing is performed under conditions in which excessive air is mixed between the ion exchange membranes, the adhesion of the ion exchange membranes to each other is reduced, and thus there is a tendency that a state in which a part of the ion exchange membranes protrudes on an end surface orthogonal to the winding axis direction, the position of the short side is deviated, and the ion exchange membranes are wound, that is, so-called winding deviation, is likely to occur. In addition, slack is generated in the manufactured ion exchange membrane roll body, and it is difficult to maintain the shape thereof. Therefore, according to the manufacturing method, an ion exchange membrane roll body in which sticking is less likely to occur and in which winding deviation is less likely to occur can be obtained. If this ion exchange membrane roll body is used, the ion exchange membranes can be continuously unwound while the speed and the tension are maintained constant. Thus, it is possible to continuously produce ion exchange membranes of a desired shape with a high yield.

[0061] Hereinafter, the ion exchange membrane roll body of the first embodiment and the manufacturing method of the ion exchange membrane roll body of the second embodiment will be described in detail.

[0062] <ION EXCHANGE MEMBRANE ROLL BODY>

[0063] The ion exchange membrane roll is a roll of ion exchange membranes in a dry state. The dry state means that the amount of water in the atmosphere and the amount of water in the ion exchange membrane are in equilibrium. The equilibrium state means, for example, that the weight change rate is within 1%. The weight change rate can be calculated, for example, by the following method. First, cut out the ion exchange membrane to obtain a sample with a size of 50 mm x 50 mm or more. Measure the weight of the sample, and let it stand in the atmosphere for 1 hour. Measure the weight of the sample after 1 hour, and calculate the weight change rate before and after the test.

[0064] The ion exchange membrane is a planar membrane having a first side and a second side orthogonal to the first side. The number of rolls of the ion exchange membrane is, for example, 50 or more, and can be 300 or more, in the case where one rotation of the ion exchange membrane is counted as one. The number of rolls has no particular upper limit, but according to one example, it is 3000 or less.

[0065] The length L of the first side is equal to or longer than the length W of the second side. The length L of the first side is, for example, 1 m or more and 2000 m or less. The length L can be 10 m or more and 100 m or less, or 50 m or more and 800 m or less. The length W of the second side is, for example, 50 mm or more and 1500 mm or less. The length W can be 100 mm or more and 1200 mm or less, or 400 mm or more and 1000 mm or less. The longer the lengths L and W, the more excellent the productivity of the ion exchange membrane sheet. The lengths L and W have no particular upper limit, but if they are in the above ranges, it is less likely that deflection due to self weight occurs. The ratio L / W of the length L of the first side to the length W of the second side is, for example, 30 or more and 2500 or less. The ratio L / W can be 100 or more and 1800 or less, or 200 or more and 1500 or less. The average thickness d of the ion exchange membrane is, for example, 10 μm or more and 200 μm or less. The average thickness d can be 15 μm or more and 150 μm or less. The thickness d can be 20 μm or more and 150 μm or less, or 25 μm or more and 100 μm or less.

[0066] Figure 1 is a perspective view schematically showing one example of an ion exchange membrane. Figure 1 The ion exchange membrane 1 shown is a thin film-like membrane having a length L of the first side longer than a length W of the second side and a thickness d.

[0067] The ion exchange membrane roll is typically cylindrical. The shape of the cross section of the ion exchange membrane roll orthogonal to the winding axis direction is typically circular. The shape of the cross section can also be elliptical.

[0068] The length Bw of the ion exchange membrane roll in the winding axis direction is the same as the length W of the second side, which is the short side of the ion exchange membrane.

[0069] In the case where the ion exchange membrane roll body is in a cylindrical shape, in a cross section of the ion exchange membrane roll body orthogonal to the winding axis direction, the length Bc of the circumference is, for example, 65 mm or more and 1800 mm or less. The length Bc can be 150 mm or more and 1500 mm or less, or 300 mm or more and 1000 mm or less. The length Bc of the circumference of the ion exchange membrane roll body can be measured by using a tape measure or the like.

[0070] In addition, in the cross section, the diameter Bl of the circle is the length in the direction orthogonal to the winding axis direction of the ion exchange membrane roll body, that is, the width, and is the height. The diameter Bl of the circle is, for example, 20 mm or more and 580 mm or less. The diameter Bl of the circle can be 45 mm or more and 480 mm or less, or 95 mm or more and 320 mm or less. The diameter Bl of the circle can be calculated from the length Bc of the circumference of the ion exchange membrane roll body.

[0071] The ratio Br / d of the radius Br (mm) of the cross section of the ion exchange membrane roll body to the average thickness d (mm) of the ion exchange membrane is, for example, 450 or more and 12000 or less. The ratio Br / d can be 1000 or more and 8000 or less, or 1500 or more and 6000 or less.

[0072] The ion exchange membrane roll body can further include a core. In the ion exchange membrane roll body, the ion exchange membrane is wound around the core in the long side direction from the end of one short side to the end of the other short side.

[0073] The core includes, for example, any of paper, paper impregnated with a resin, a resin, and a metal. The core is preferably formed of a resin because of less deformation. As the resin, for example, polyethylene, polystyrene, polypropylene, ABS, or the like can be given. In addition, as the core made of another resin, an impregnation type core in which carbon fibers or glass fibers are wound to be in a cylindrical shape, and a thermoplastic resin such as a phenol resin or an epoxy resin is impregnated therein and cured can be used.

[0074] The core is typically in a cylindrical shape. The length Cw of the core in the winding axis direction when the core is mounted to the winding axis is preferably equal to or longer than the length W of the second side of the ion exchange membrane. The length Cw of the core in the winding axis direction is, for example, 10 mm or more and 1600 mm or less. The length Cw of the core can be 100 mm or more and 1300 mm or less, or 400 mm or more and 1100 mm or less. The difference Cw-Bw between the length Bw of the ion exchange membrane roll body in the winding axis direction and the length Cw of the core in the winding axis direction is, for example, 0 mm or more and 400 mm or less. The difference Cw-Bw is preferably 20 mm or more and 300 mm or less.

[0075] In a cross section of the winding core orthogonal to the winding axis direction, the length Cc of the circumference is smaller than the length Bc of the circumference of the ion exchange membrane roll. The length Cc of the circumference is, for example, 30 mm or more and 630 mm or less. The length Cc can be 150 mm or more and 600 mm or less, or 200 mm or more and 560 mm or less. The ratio Bc / Cc of the length Bc of the circumference of the ion exchange membrane roll to the length Cc of the circumference of the winding core is, for example, 1.1 or more and 3.3 or less. The ratio Bc / Cc is preferably 1.2 or more and 2.5 or less. The length Cc of the circumference of the winding core can be measured by using a tape measure or the like. The length Cc of the circumference of the winding core can be calculated from the diameter Cl of the winding core.

[0076] In addition, in the cross section of the winding core, the diameter Cl of the circle is the length in the direction orthogonal to the winding axis direction, that is, the width, and is the height. The diameter Cl of the circle is, for example, 10 mm or more and 200 mm or less. The diameter Cl of the circle can be 50 mm or more and 190 mm or less, or 70 mm or more and 180 mm or less. The diameter Cl of the circle can be measured using a tape measure or the like.

[0077] In the ion exchange membrane roll, the ratio Br / Cr of the radius Cr of the winding core to the radius Br of the cross section of the ion exchange membrane roll is, for example, 1.1 or more and 3.3 or less. The ratio Br / Cr can be 1.2 or more and 3.0 or less, or 1.5 or more and 2.8 or less.

[0078] Figure 2 is a perspective view schematically showing an example of the ion exchange membrane roll of the embodiment. Figure 2 The ion exchange membrane roll 10 shown includes a winding core 2 and an ion exchange membrane portion 3. The ion exchange membrane portion 3 includes Figure 1 The ion exchange membrane 1 shown is wound around the winding core 2. Figure 2 The ion exchange membrane roll 10 shown is cylindrical elongated in the winding axis direction. The ion exchange membrane roll 10 has a length Bw in the winding axis direction and a length Bl in the direction orthogonal to the winding axis direction. Figure 2 The winding core 2 shown is cylindrical. The winding core 2 has a length Cw in the winding axis direction and a length Cl in the direction orthogonal to the winding axis direction.

[0079] The air layer rate of the ion exchange membrane roll is greater than 5% and 50% or less. The air layer rate can be calculated by the following formula (I).

[0080] Air layer rate (%) = (Aa - dL) / Aa x 100 (I)

[0081] In formula (I), Aa is the average area of the cross section of the ion exchange membrane in the ion exchange membrane roll in a direction orthogonal to the direction of the roll axis. d is the average thickness of the ion exchange membrane. L is the length of the first side of the ion exchange membrane.

[0082] The air layer rate can refer to the proportion of air between the ion exchange membranes wound in the ion exchange membrane roll. That is, the air layer rate is the value (Aa-dL) / (Aa) obtained by dividing the value Aa-dL obtained by subtracting the area dL of the side of the long side of the ion exchange membrane from the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll by the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll. The cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll is greater than the area dL of the side of the ion exchange membrane, that is, the air layer rate exceeds 0%, which means that in the ion exchange membrane roll, air is mixed between the ion exchange membranes. In other words, the cross-sectional area Aa of the ion exchange membrane in the ion exchange membrane roll is equal to the area dL of the side of the ion exchange membrane, that is, the air layer rate is 0%, which means that in the ion exchange membrane roll, the ion exchange membranes are wound without gaps.

[0083] The ion exchange membrane roll with an air layer rate greater than 5% has a tendency that the adhesion of the ion exchange membranes to each other is inhibited and the occurrence of blocking is not easy. The ion exchange membrane roll with an air layer rate of 50% or less has a tendency that the shape is maintained and the occurrence of winding deviation is not easy.

[0084] The calculation method of the air layer rate will be described with reference to the drawings.

[0085] Figure 3 is a cross-sectional view schematically showing an example of the cross section of the ion exchange membrane roll. Figure 3 is a cross-sectional view obtained by cutting the ion exchange membrane roll 10 shown in Figure 2 along a direction orthogonal to the direction of the roll axis. In the ion exchange membrane portion 3, air layers are provided between the ion exchange membranes 1.

[0086] First, the circumference of the ion exchange membrane roll 10 is measured at 10 points set at equal intervals in the direction of the roll axis of the ion exchange membrane roll, using a tape measure or the like, and the average of the measurements is used to determine the length Bc of the circumference of the ion exchange membrane roll 10. Next, the diameter of the two end portions of the core 2 is measured using a tape measure or the like, and the average of the measurements is used to determine the diameter Cl of the core. The diameter Bl of the ion exchange membrane roll 10 is calculated from the length Bc of the circumference of the ion exchange membrane roll 10 and the constant pi 3.14, and the radius Br of the ion exchange membrane roll 10 is calculated from the diameter Bl. The cross-sectional area Ba of the ion exchange membrane roll 10 is calculated from the radius Br and the constant pi 3.14. The radius Cr is calculated from the diameter Cl of the core 2, and the cross-sectional area Ca of the core 2 is calculated from the radius Cr and the constant pi 3.14. The cross-sectional area Ba-Ca of the ion exchange membrane portion 3 is obtained by subtracting the cross-sectional area Ca of the core 2 from the cross-sectional area Ba of the ion exchange membrane roll 10. The cross-sectional area Ba-Ca is taken as the cross-sectional area Aa of the ion exchange membrane portion 3, i.e., the average area of the cross section of the ion exchange membrane in the ion exchange membrane roll in a direction orthogonal to the roll axis direction.

[0087] Next, the ion exchange membrane 1 is unwound from the ion exchange membrane roll 10, and the length L of the first side is measured. The length L can be calculated from the speed at which the ion exchange membrane is transported during manufacture of the ion exchange membrane roll and the time taken to wind the roll, or can be measured using a roll length counter or the like provided in the ion exchange membrane roll manufacturing apparatus or slitting apparatus. The thickness of the ion exchange membrane is measured at 10 points set at equal intervals in the direction of the first side of the ion exchange membrane 1. The average of the measurements is taken as the average thickness d of the ion exchange membrane 1. The cross-sectional area dL of the side of the ion exchange membrane 1 is calculated by multiplying the length L of the first side of the ion exchange membrane 1 by the average thickness d.

[0088] The cross-sectional area Aa-dL of the air present between the ion exchange membranes 1 in the ion exchange membrane portion 3 is calculated by subtracting the cross-sectional area dL of the ion exchange membrane 1 from the cross-sectional area Aa of the ion exchange membrane portion 3. The proportion of air in the cross section, i.e., the air layer ratio, can be calculated by dividing the cross-sectional area Aa-dL of the air by the cross-sectional area Aa of the ion exchange membrane portion.

[0089] The air layer ratio is preferably 7% or more. If the air layer ratio is high, air is sandwiched between the ion exchange membranes, and thus there is a tendency that adhesion is less likely to occur. Generally, in a film that does not have hygroscopicity, the lower the air layer ratio, the less likely winding displacement occurs during storage and transportation. However, in the ion exchange membranes in a dry state, water in the atmosphere can be absorbed, and the volume of the film can increase. When the air layer ratio is 7% or more, the air layer can absorb the volume change of the ion exchange membranes caused by changes in temperature and humidity during storage and transportation. Thus, for example, displacement of the position of a portion of the ion exchange membranes in the side surface portion of the ion exchange membrane roll can be suppressed due to the volume increase of the ion exchange membranes in a dry state. The air layer ratio is more preferably 10% or more, and further preferably 15% or more. On the other hand, if the air layer ratio is too high, the positions of the ion exchange membranes can be displaced in the step of producing the ion exchange membrane roll. In addition, during storage and transportation of the ion exchange membrane roll, winding displacement is likely to occur when an impact is applied to the side surface of the ion exchange membrane roll orthogonal to the winding axis direction. From the viewpoint of less likely occurrence of such winding displacement, the air layer ratio is preferably 38% or less, more preferably 35% or less, and further preferably 30% or less.

[0090] The hardness of the ion exchange membrane roll is, for example, 80 or more and 95 or less. The hardness can be measured using a hardness tester of ASKER hardness tester C type. Specifically, the value after the hardness tester of ASKER hardness tester C type is pressed vertically against the top surface of the ion exchange membrane roll so as to be in close contact is measured. The average value of the hardness measured at 10 points set at equal intervals along the length in the winding axis direction except for 20 mm at both ends in the winding axis direction of the ion exchange membrane roll is taken as the hardness of the ion exchange membrane roll. That is, the hardness refers to the hardness in the direction orthogonal to the winding axis direction of the ion exchange membrane roll. In the case where the hardness is 100, it means that the hardness of the ion exchange membrane roll is substantially equal to the hardness of the winding core, and it means that in the ion exchange membrane roll, an air layer is hardly formed between the ion exchange membranes. The hardness is more preferably 82 or more and 94 or less, and further preferably 87 or more and 92 or less. The ion exchange membrane roll having the hardness in this range has a tendency that adhesion and winding displacement are less likely to occur.

[0091] Note that the ion exchange membrane in a dry state sometimes swells due to absorption of water in the atmosphere. Thus, the measurement of the air layer ratio and the hardness described above is performed in an environment where the temperature is 20°C or more and 30°C or less and the relative humidity is 30% or more and 50% or less. In addition, the ion exchange membrane roll that has been left in the above environment for 24 hours or more is used as a sample.

[0092] (Ion exchange membrane)

[0093] The ion exchange membrane can be formed only of the ion exchange resin, or can be obtained by supporting the ion exchange resin on a porous base material. The ion exchange membrane can be a cation exchange membrane, or can be an anion exchange membrane. The ion exchange membrane can be a bipolar membrane including both a cation exchange membrane and an anion exchange membrane.

[0094] The ion exchange resin is a resin having an ion exchange group. The ion exchange group can be a cation exchange group, or can be an anion exchange group, or can include both. The cation exchange group, for example, includes at least one functional group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, and a phosphonic acid group. The anion exchange group, for example, includes at least one functional group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, an imidazolium group, a primary amino group, a secondary amino group, and a tertiary amino group. As the ion exchange group, for example, it is preferable to include at least one functional group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, and an imidazolium group, and it is more preferable to include at least one functional group selected from the group consisting of a quaternary ammonium group and a pyridinium group.

[0095] As the ion exchange resin, at least one of a hydrocarbon-based resin and a fluorine-based resin can be used. As the hydrocarbon-based resin, a styrene-based resin, an acrylic-based resin, or the like can be used. As the fluorine-based resin, a resin having a perfluorocarbon skeleton can be used. As the ion exchange resin, it is preferable to use a hydrocarbon-based resin, and it is more preferable to use a copolymer of a styrene derivative and a divinylbenzene derivative.

[0096] The base material functions as a support for the ion exchange resin. As the base material, for example, a porous film, a woven fabric, a nonwoven fabric, a sponge, a film, or the like can be used. The base material is preferably a porous film. In the case where a porous film is used as the base material, it is preferable that the ion exchange resin is filled in the pores of the base material.

[0097] The base material is, for example, a polyolefin resin, a fluorine-based resin, a polyacrylonitrile, a polyvinyl chloride, a polyester, a polyamide, a polysulfone, a polyethersulfone, a polyphenylsulfone, a polyphenylene sulfide, a polyimide, a polyetherimide, a polyamideimide, a polycarbonate, a polyacrylate, a cellulose acetate, a polyether ether ketone, or a copolymer thereof. The polyolefin resin includes a polyethylene, a polypropylene, a polybutadiene, a polymethylpentene, a polybutene, a polypentene, a polyhexene, a polymethylheptene, and a copolymer thereof. The fluorine-based resin includes a polytetrafluoroethylene, a poly(tetrafluoroethylene-hexafluoropropylene), a polyvinylidene fluoride, a polyhexafluoropropylene, a polytrifluorochloroethylene, and a copolymer thereof. The base material preferably includes a polyolefin resin, and more preferably includes a polyethylene or a polypropylene.

[0098] The film thickness of the base material is, for example, 5 μm or more and 200 μm or less, preferably 5 μm or more and 170 μm or less, more preferably 10 μm or more and 120 μm or less, and further preferably 15 μm or more and 100 μm or less.

[0099] The porosity of the base material is, for example, 10% or more and 55% or less, preferably 20% or more and 50% or less, and more preferably 30% or more and 45% or less.

[0100] Method for manufacturing ion exchange membrane in wet state

[0101] The ion exchange membrane in wet state is manufactured, for example, by the following method.

[0102] First, a first structure is obtained by bringing the polymerizable composition into contact with the base material, and then a second structure is obtained by curing the polymerizable composition, and the ion exchange membrane in wet state is obtained by introducing ion exchange groups to the second structure.

[0103] The polymerizable composition contains, for example, a monomer of a precursor of an ion exchange resin or a monomer of an ion exchange resin, and a radical polymerizable monomer that can be polymerized with these monomers.

[0104] The polymerizable composition is typically liquid at normal temperature and normal pressure. Here, normal temperature means a temperature of 20°C or higher and 40°C or lower, and normal pressure means 1 atm.

[0105] As the monomer of a precursor of an ion exchange resin, for example, styrene derivatives such as chloromethylstyrene, bromomethylstyrene, and iodomethylstyrene can be given. As the monomer of an ion exchange resin, for example, styrene derivatives having an ion exchange group such as a quaternary ammonium group can be given. As the monomer of an ion exchange resin, it is preferable to use vinylbenzyltrimethylammonium and a salt thereof, and it is more preferable to use vinylbenzyltrimethylammonium chloride.

[0106] The proportion of the monomer of a precursor of an ion exchange resin or the monomer of an ion exchange resin in the polymerizable composition is, for example, 5% by mass or more and 95% by mass or less. The proportion is preferably 50% by mass or more, preferably 60% by mass or more, more preferably 65% by mass or more, and further preferably 68% by mass or more. When the proportion is high, there is a tendency that an ion exchange resin having a large amount of ion exchange groups per unit mass can be obtained.

[0107] The radical polymerizable monomer contains a cross-linkable radical polymerizable monomer that functions as a cross-linking agent. The cross-linkable radical polymerizable monomer has two or more radical polymerizable groups in one molecule. As the radical polymerizable group, for example, a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, and the like can be given, and it is preferable to use a vinyl group. The radical polymerizable monomer can contain a radical polymerizable monomer having one radical polymerizable group in one molecule that does not function as a cross-linking agent.

[0108] As the cross-linkable radical polymerizable monomer, at least one selected from the group consisting of a divinyl compound having 2 vinyl groups, a diallyl compound having 2 allyl groups, and a diene, for example, is used.

[0109] Specific examples of the cross-linkable radical polymerizable monomer can be mentioned divinylbenzene, divinylbenzene derivatives, divinylsulfone, butadiene, chlorobutadiene, divinylphenyl, trivinylbenzene, divinyl naphthalene, diallylamine, divinylpyridine, diallylisocyanurate, and the like. As the radical polymerizable monomer, at least one selected from the group consisting of divinylbenzene, divinylbenzene derivatives is preferably used.

[0110] In the polymerizable composition, the proportion of the cross-linkable radical polymerizable monomer is, for example, 0.1 mass% or more and 20 mass% or less, preferably 1 mass% or more and 18 mass% or less, more preferably 3 mass% or more and 15 mass% or less. When the proportion is high, there is a tendency that the mechanical strength is improved. When the proportion is too high, the performance of the ion exchange resin can be reduced.

[0111] The polymerizable composition can further contain a polymerization initiator, an organic solvent, a polymerization inhibitor, an antioxidant, a polymerization inhibitor, a plasticizer, a surfactant, and the like, and the like, which are well known.

[0112] As the polymerization initiator, at least one of a thermal polymerization initiator and a photopolymerization initiator is used. As the thermal polymerization initiator, benzoyl peroxide, p-chlorobenzoyl peroxide, decanoyl peroxide, lauryl peroxide, acetyl peroxide, t-butyl (2-ethylhexanoyl) peroxyhexanoate, t-butyl peroxyoctanoate, and the like can be mentioned. As the photopolymerization initiator, 1-phenyl-2-hydroxy-2-methylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-hydroxy-4'- (2'-hydroxyethoxy)-2-methylpropiophenone, and the like can be mentioned.

[0113] In the polymerizable composition, the proportion of the polymerization initiator is, for example, 0.1 mass% or more and 10 mass% or less.

[0114] The organic solvent is used to adjust the viscosity of the polymerizable composition and to improve the solubility of the monomer. As the organic solvent, at least one selected from the group consisting of methanol, dimethyl sulfoxide (DMSO), ethylene glycol (EG), and propylene glycol, for example, is used.

[0115] The proportion of the organic solvent in the polymerizable composition is, for example, 1% by mass or more and 40% by mass or less. When the proportion of the organic solvent is high, the viscosity of the polymerizable composition decreases, and the production efficiency can be improved. On the other hand, when the proportion of the organic solvent is high, the ion exchange resin of the ion exchange membrane can have voids, and thus the performance of the ion exchange membrane can decrease. The proportion of the organic solvent in the polymerizable composition is preferably 30% by mass or less, and more preferably 25% by mass or less. The proportion can be determined by, for example, NMR or liquid chromatography.

[0116] As the polymerization inhibitor, at least one selected from the group consisting of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxide (4-OH-TEMPO), 4-tert-butylcatechol (TBC), cupferron, and benzoquinone is used, for example.

[0117] The proportion of the polymerization inhibitor in the polymerizable composition is, for example, 0.0001% by mass or more and 2% by mass or less, and preferably 0.001% by mass or more and 1.0% by mass or less. The proportion can be determined by, for example, gas chromatography.

[0118] The polymerizable composition preferably does not contain water. When the polymerizable composition contains water, the components such as the polymerizable monomer and the polymerization initiator can be precipitated. The concentration of water in the polymerizable composition is preferably 10% by mass or less. The lower limit of the concentration of water is 0% by mass according to one example, and 100 ppm according to another example. The concentration can be determined by, for example, Karl Fischer moisture measurement or gas chromatography.

[0119] Hereinafter, as one example, the details of the method for producing an ion exchange membrane using a porous base material as a support will be described.

[0120] The method for contacting the polymerizable composition with the base material is not particularly limited. The polymerizable composition can be applied to the base material, can be sprayed, or can be added dropwise. Alternatively, the base material can be impregnated in the polymerizable composition. The amount of the polymerizable composition with respect to the base material is not particularly limited as long as the pores in the base material are filled. The amount in which the pores are filled can be calculated from the densities of the base material and the polymerizable composition used. In order to fill the polymerizable composition into the inside of the base material, a method in which the base material is impregnated in the polymerizable composition is preferred. In order to improve the adhesion to the polymerizable composition, the base material can be subjected to surface treatment such as corona treatment, glow discharge treatment, alkali treatment, or the like.

[0121] In the first structure, the polymerizable composition is supported on the substrate. When the polymerizable composition is cured, at least one main surface of the first structure is preferably covered with a resin film. By covering with the resin film, the smoothness of the surface of the ion exchange membrane can be improved. In addition, in the case where the first structure is in the form of a laminate or a roll, the case where the upper and lower layers are integrated due to polymerization of the polymerizable composition can be prevented. As the resin of the resin film, for example, from the viewpoints of heat resistance and peelability, a polyester resin such as polyethylene terephthalate, a fluororesin such as perfluoroethylene-propylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, and the like are used. The resin film can be a release film on which coating is performed on the surface. The resin film can be appropriately selected depending on the components of the polymerizable composition, and from the viewpoints of heat resistance and peelability, a polyester film such as polyethylene terephthalate is preferred.

[0122] The curing method of the polymerizable composition includes, for example, thermal polymerization or photopolymerization. The heating temperature when thermal polymerization is performed is, for example, 40°C or higher and 130°C or lower, as long as it is lower than the melting point of the substrate as the support. In the case where a polyethylene substrate is used as the support, for example, the temperature is 40°C or higher and 130°C or lower. Photopolymerization is performed, for example, by irradiation of ultraviolet rays. As the irradiation source, for example, an ultraviolet light-emitting diode (LED), a halogen lamp, a xenon lamp, a tungsten lamp, a mercury lamp, and the like are used. From the viewpoints of easiness of controlling the irradiation wavelength and non-heating, an LED is preferably used. The curing method of the polymerizable composition can be, for example, a combination of thermal polymerization and photopolymerization. At this time, it is preferred that the first structure is subjected to photopolymerization and then subjected to thermal polymerization.

[0123] As for introduction of the ion exchange group to the ion exchange resin precursor of the second structure, for example, a method in which the second structure is immersed in a treatment liquid containing the ion exchange group to be introduced is performed. Note that, in the case where a polymerizable composition containing a monomer of the ion exchange resin is used, since the second structure contains the ion exchange resin, the introduction of the ion exchange group can be omitted. The ion exchange membrane obtained by the above method can be further subjected to a substitution treatment of the counter ion.

[0124] The production of the ion exchange membrane can be performed in a roll-to-roll form. While referring to Figure 4 A roll-to-roll production example will be described in more detail. Figure 4 is a schematic view schematically showing an example of a polymerizable composition immersion device. Figure 4The illustrated polymerizable composition impregnation device 100 includes an unwinding section 101, a conveying section 102, and a winding section 103. Motors, not shown, are installed on the unwinding section 101, the conveying section 102, and the winding section 103, and a controller is connected to the motors. Brakes can also be installed on the unwinding section 101, the conveying section 102, and the winding section 103, respectively. A winding body of a base material is provided on the unwinding section 101. The conveying section 102 includes a nip roller 104, a first conveying roller 105, a second conveying roller 106, a third conveying roller 107, and a tank T between the first conveying roller 105 and the third conveying roller 107. The polymerizable composition PC is housed in the tank T. The second conveying roller 106 is located in the tank T. A winding core is provided on the winding section 103. Between the unwinding section and the winding section, a tension cutoff mechanism such as a nip roller, a suction roller, an S roll mechanism based on a plurality of rollers with an increased nip angle, a conveying roller, and the like, not shown, can also be provided. In addition, a tension control mechanism such as a slack adjust roller and the like can also be provided in order to absorb tension variations. A proximity roller, a contact roller, and the like can also be provided on the winding section 103.

[0125] First, a winding body of a base material is provided on the unwinding section 101, and a winding core is provided on the winding section 103. The motors of the unwinding section 101 and the winding section 103 are operated, and one end of the short side of the base material is unwound from the winding body of the base material and conveyed into the polymerizable composition in the tank T. In the tank T, the polymerizable composition is carried on the conveyed base material. By gripping the base material on which the polymerizable composition is carried with the nip roller 104 provided on the conveying roller 107, excess polymerizable composition can be removed. In addition, at this time, by causing the resin film to be laminated to at least one main surface and gripped from the extraction mechanism, not shown, the resin film can be laminated to the surface of the base material on which the polymerizable composition is carried. The lamination of the resin film can be either one side or both sides, and in the case where polymerization is performed after the first structure body winding body is produced, by being provided as only one side, the cost can be suppressed. In addition, in this case, the nip roller 104 can also be installed on the winding section 103. The resulting laminated film is further conveyed and wound on the winding core of the winding section 103 to obtain a winding body of the laminated film. The winding body of the laminated film is taken out from the winding section 103, provided in an oven, and the polymerizable composition is heat-polymerized. Thus, a winding body of a laminated film including a second structure body is obtained.

[0126] Note that, Figure 4The illustrated polymerizable composition impregnation device 100 can be provided with a polymerization mechanism between the nip roll 104 and the winding section 103. At this time, by laminating a resin film to both surfaces of the substrate on which the polymerizable composition is supported, it is easy to make the smoothness of the front and back surfaces of the resulting ion exchange membrane constant, and therefore it is preferable to laminate a resin film to both surfaces. The polymerization mechanism includes at least one of a UV irradiation device and a heating device. For example, by irradiating UV or heating the laminated film being conveyed from the nip roll 104 to the winding device 103, the polymerizable composition is cured. By winding the resulting laminated film containing the second structure around the winding core of the winding device 103, a winding body of the laminated film containing the second structure is obtained.

[0127] Next, the winding body of the laminated film containing the second structure is immersed in a treatment liquid containing an ion exchange group, ion exchange groups are introduced, and then immersed in water to be cleaned. Thereby, a winding body of the ion exchange membrane in a wet state is obtained. Note that when a polymerizable composition containing a monomer of an ion exchange resin is used, the introduction of the ion exchange group can be omitted. At this time, the resin film can be peeled or not peeled, but in the case of peeling, it is easy to introduce the ion exchange group, and therefore peeling is preferable.

[0128] The ion exchange membrane obtained by the above method can be further subjected to a substitution treatment of counter ions. The substitution treatment of counter ions is performed, for example, by immersing the winding body of the ion exchange membrane in a treatment liquid having desired counter ions and then immersing in water to be cleaned. Note that when a polymerizable composition containing a monomer of an ion exchange resin is used, by this substitution treatment of counter ions, a winding body of the ion exchange membrane in a wet state is obtained.

[0129] Note that in the case where the introduction of the ion exchange group does not require time or the like, the introduction of the ion exchange group and the substitution treatment of counter ions can be continuously performed, for example, in a roll-to-roll form. That is, it is also possible to convey the second structure to a tank containing a treatment liquid containing an ion exchange group or a treatment liquid having desired counter ions just before the winding device 103, and further convey and wind the second structure after being immersed in these treatment liquids.

[0130] Note that in the case where the ion exchange membrane is in the form of a laminated film, for example, the laminated film can be peeled from the laminated film in a roll-to-roll form, and only the ion exchange membrane is wound, thereby obtaining a winding body of the ion exchange membrane in a wet state.

[0131] (Method for manufacturing ion exchange membrane winding body)

[0132] The manufacturing method of the ion exchange membrane roll body of the embodiment includes a step of transporting the dry ion exchange membrane to the winding core at a transport speed of 0.75 m / min or more and 30 m / min or less, and a step of winding the dry ion exchange membrane to the winding core at a winding tension of 3 N / m or more and 100 N / m or less. At the winding, the dry ion exchange membrane is wound to the winding core in a manner that no pressure is applied to the winding core or the surface of the dry ion exchange membrane wound to the winding core.

[0133] The details of the manufacturing method are described below.

[0134] First, the winding body of the ion exchange membrane in the wet state is prepared by, for example, the above-described method. Next, the end portion of one short side of the ion exchange membrane is unwound from the winding body of the ion exchange membrane in the wet state, and the ion exchange membrane is transported. The wet ion exchange membrane transported is subjected to a drying process, and the dry ion exchange membrane is further transported toward the winding core. The dry ion exchange membrane transported is wound to the winding core, and a dry ion exchange membrane roll body is obtained. At this time, by adjusting the transport speed of the dry ion exchange membrane, the winding tension at the time of winding of the ion exchange membrane, and the pressing at the time of winding of the ion exchange membrane, the air layer ratio and the hardness in the ion exchange membrane roll body can be adjusted. Note that a dry ion exchange membrane roll body can also be used instead of the wet ion exchange membrane roll body. In this case, the drying process can be omitted.

[0135] That is, if the transport speed of the ion exchange membrane is fast, the atmosphere is transported to the ion exchange membrane, and the atmosphere easily mixes between the ion exchange membranes of the ion exchange membrane roll body, and thus the air layer ratio tends to increase. The transport speed is preferably 0.75 m / min or more and 30 m / min or less. If the transport speed is within this range, the ion exchange membrane roll body having a moderate air layer can be obtained. From the viewpoint of improving the production efficiency, the transport speed is preferably 3 m / min or more, more preferably 5 m / min or more, and further preferably 10 m / min or more. The transport speed can be calculated, for example, from the rotation speed and the outer diameter of the transport roller provided in front of the winding section. The rotation speed of the roller can be measured by the encoder of the motor installed in the roller.

[0136] If the winding tension of the ion exchange membrane when wound around the winding core is high, air is less likely to mix between the ion exchange membranes of the ion exchange membrane roll, and thus there is a tendency for the air layer ratio to decrease. The winding tension is preferably 3 N / m or more and 100 N / m or less. If the winding tension is within this range, there is a tendency for an ion exchange membrane roll having a moderate air layer to be obtained. The winding tension is preferably 5 N / m or more and 50 N / m or less, and can also be 10 N / m or more and 40 N / m or less. This winding tension can be measured, for example, by a load cell provided to the conveying roller. In addition, by feeding back the measured tension to the unwinding section and the winding section, the torque of the motor and the rotation speed of the roller can be adjusted, and the tension can be controlled to be a set value.

[0137] It is preferable that no pressure be applied to the surface of the winding core or the ion exchange membrane wound around the winding core. That is, for example, if a contact roller or the like is used to wind the ion exchange membrane while applying pressure to the surface of the wound ion exchange membrane, the air mixed between the ion exchange membranes can be squeezed out, and thus the air layer ratio of the ion exchange membrane roll can be 5% or less. Therefore, when manufacturing the ion exchange membrane roll, it is preferable that no contact roller or the like be used, and the ion exchange membrane be wound in a manner in which no pressure is applied to the surface of the winding core or the ion exchange membrane wound around the winding core.

[0138] The manufacturing of the ion exchange membrane roll in the dry state can be performed in a roll-to-roll manner. The manufacturing of the ion exchange membrane roll in the dry state will be described in more detail below. Figure 5 The manufacturing of the ion exchange membrane roll in the dry state will be described in more detail below. Figure 5 is a schematic view schematically showing an example of an ion exchange membrane roll manufacturing apparatus. Figure 5 The ion exchange membrane roll manufacturing apparatus 300 shown includes an unwinding section 301, a conveying section 302, and a winding section 303. Motors not shown are installed on the unwinding section 301, the conveying section 302, and the winding section 303, and a controller is connected to the motors. Brakes can also be installed on the unwinding section 301, the conveying section 302, and the winding section 303, respectively. The ion exchange membrane roll in the wet state is provided to the unwinding section 301. The conveying section 302 has a tension cutting mechanism 304, a conveying roller 305, a proximity roller 306, a cleaning mechanism and a drying mechanism not shown. A winding core for the ion exchange membrane roll in the dry state is provided to the winding section 303. The proximity roller 306 is provided in the vicinity of the winding core in a manner so as not to contact the surface of the winding core or the ion exchange membrane wound around the winding core of the winding section 303. A conveying roller or the like not shown can be provided in the ion exchange membrane roll manufacturing apparatus 300. The tension cutting mechanism 304 can use a pinch roller, a suction roller, an S-grinding mechanism based on a plurality of rollers having an increased included angle, or the like. In addition, in order to absorb the tension variation, a slack adjusting roller or the like tension control mechanism is preferably provided. In addition, a flatting mechanism such as an expansion roller or a pinch roller can also be provided before the winding section 303. The cleaning device and the proximity roller 306 can also be omitted, and an inspection mechanism or a destaticizing mechanism can also be provided.

[0139] First, a wet state ion exchange membrane roll is set in the unwinding device 301, and a winding core is set in the winding section 303. The motors of the unwinding section 301 and the winding section 303 are operated, and one short side of the wet state ion exchange membrane is unwound from the wet state ion exchange membrane roll. The cleaning mechanism cleans the ion exchange membrane using a cleaning liquid such as water. The cleaned ion exchange membrane is further transported to the drying mechanism. The drying mechanism dries the transported cleaned ion exchange membrane by heating using, for example, a heater or hot air. The obtained dry state ion exchange membrane is further transported to the winding section 303, and is wound around the winding core. In this way, a roll of the dry state ion exchange membrane is obtained. The winding core can be removed from the obtained roll.

[0140] The obtained dry state ion exchange membrane roll can be further subjected to a slitting process using a slitting device. The slitting process divides the ion exchange membrane into a plurality of pieces in a direction parallel to the first side. The slitting process is performed in a roll-to-roll manner. That is, the ion exchange membrane that has been transported from the ion exchange membrane roll and subjected to the slitting process is wound around the winding core in the same manner as the ion exchange membrane roll. The slitting process can be performed by pressing a knife against the ion exchange membrane that is transported onto a hard metal roller or ceramic roller in the slitting device, or by abutting the knife against the ion exchange membrane that is transported in a hollow such as between the transport rollers, or in a groove provided on the metal roller. The slitting device is provided, for example, immediately before the winding section 303. When the slitting device is provided, the winding section can obtain a roll of the ion exchange membrane that is cut to a desired width by providing a plurality of winding sections that match the width after the slitting. When the slitting device is provided, the ion exchange membrane can be subjected to a swing process by providing a roller type traversing device immediately before the slitting device, and swinging the ion exchange membrane left and right. Figure 5 The slitting process can be continuously performed by further providing a slitting process mechanism in the ion exchange membrane roll manufacturing device 300 shown in FIG. 1. The slitting process mechanism is provided, for example, with a knife that can cut the ion exchange membrane. The slitting process mechanism can be further provided with a metal roller or a ceramic roller. The cutting of the ion exchange membrane can be performed by pressing the knife against the ion exchange membrane that is transported onto a hard metal roller or ceramic roller in the slitting process mechanism, or by abutting the knife against the ion exchange membrane that is transported in a hollow such as between the transport rollers, or in a groove provided on the metal roller. The slitting process mechanism is provided, for example, immediately before the winding section 303. When the slitting process mechanism is provided, the winding section can obtain a roll of the ion exchange membrane that is cut to a desired width by providing a plurality of winding sections that match the width after the slitting. When the slitting mechanism is provided, the ion exchange membrane can be subjected to a swing process by providing a roller type traversing device immediately before the slitting mechanism, and swinging the ion exchange membrane left and right.

[0141] When the slitting process is performed using a slitting device after the dry state ion exchange membrane roll is produced, the air layer ratio and the hardness in the ion exchange membrane roll can be adjusted by adjusting the transport speed of the dry state ion exchange membrane in the slitting device, the winding tension when the ion exchange membrane is wound, and the pressure when the ion exchange membrane is wound. The slitting device can be performed using the same mechanism as the aforementioned slitting mechanism.

[0142] (Method for manufacturing ion exchange sheet)

[0143] The ion exchange membrane roll body of the embodiment is used, for example, for the production of an ion exchange sheet. The ion exchange sheet refers to an ion exchange membrane in a dry state that does not have a long thin film shape. The ion exchange sheet can be rectangular, can be square, can be polygonal, can be circular, or can be elliptical.

[0144] The ion exchange sheet is provided, for example, in the interior of a device for producing pure water, a device for desalination treatment of seawater, a desalination treatment device, a fuel cell, and a water electrolysis device, and functions as a separator. The ion exchange sheet is preferably used for a membrane electrode assembly of a fuel cell or a water electrolysis device.

[0145] If the ion exchange membrane roll body of the embodiment is used, the ion exchange membrane can be continuously unwound without wrinkles or twisting while the speed and tension are kept constant, and thus the ion exchange sheet can be continuously produced at a high yield.

[0146] The method for producing an ion exchange sheet includes, for example, a step of unwinding an ion exchange membrane from an ion exchange membrane roll body in a dry state, and a step of cutting the unwound ion exchange membrane. Note that the cutting includes a step of cutting the ion exchange membrane in a direction parallel to the second edge, and a step of punching into a predetermined shape. The method for cutting the ion exchange membrane is not particularly limited. The cutting of the ion exchange membrane is performed, for example, using a metal knife.

[0147] A membrane electrode assembly is obtained, for example, by laminating an electrode on an ion exchange sheet. The membrane electrode assembly can also be obtained by cutting a long membrane electrode assembly obtained by joining an ion exchange membrane and an electrode.

[0148] Example

[0149] Hereinafter, the present application will be described in detail with reference to examples, but the present application is not limited to these examples.

[0150] <Example 1>

[0151] (Preparation of the polymerizable composition)

[0152] A chloromethylstyrene (95 parts by mass), a 57 mass% divinylbenzene-styrene solution (5 parts by mass), a polymerization initiator (trade name: Perbutyl O, 5 parts by mass), and an epoxy compound (trade name: Epolight 40E, 5 parts by mass) were mixed to obtain a polymerizable composition.

[0153] (Production of the roll body of the ion exchange membrane in a wet state)

[0154] As a substrate for an ion exchange membrane, a roll body of a porous polyethylene film having a porosity of 44%, a thickness of 25 μm, a width of 1000 mm, and a length of 400 m was used.

[0155] The substrate was unwound, dipped in a tank containing the polymerizable composition, and the polymerizable composition was supported on the substrate. A 50-μm-thick polyethylene terephthalate film was attached to one side of the substrate, and the substrate was wound on a metal roll on which hard chromium plating had been performed, to obtain a roll of a laminated film containing the first structure.

[0156] The obtained roll was heated at 80°C for 5 hours under nitrogen pressurization at 0.3 MPa, and the polymerizable composition in the porous film was polymerized, to obtain a roll of a laminated film containing the second structure.

[0157] The laminated film was unwound from the obtained roll, and the polyethylene terephthalate film was peeled off and rewound, to produce a roll of only the second structure without the polyethylene terephthalate film. The second structure roll was dipped in an aqueous solution containing 6 mass% trimethylamine and 25 mass% acetone at room temperature for 16 hours, and the chloromethylstyrene polymer portion was aminated. Then, the roll was dipped in a 0.5 mol / L aqueous potassium bicarbonate solution, to exchange the counter ion of the quaternary ammonium salt group in the membrane from chloride ion to bicarbonate ion. Then, the roll was dipped in pure water to perform cleaning, to obtain a roll of an ion exchange membrane in a wet state.

[0158] (Production of the first and second ion exchange membrane rolls in a dry state)

[0159] The roll of the ion exchange membrane in a wet state was unwound, and hot air at 40°C was blown in the conveyance section after unwinding, to dry the ion exchange membrane. The dried membrane was conveyed to a winding section, and was wound around a glass fiber reinforced plastic core having an inner diameter of 153 mm, a wall thickness of 10 mm, and a width of 1200 mm, to produce a roll of an ion exchange membrane in a dry state. The conveyance speed at this time was 3 m / min, and the winding tension was 15 N / m. At the time of winding, a contact roll was not used, and a proximity roll was used. The length of the obtained first ion exchange membrane roll was 400 m, and the circumference was 688 mm. The average thickness of the ion exchange membrane in a dry state was 28 μm. In addition, the air layer rate calculated from the circumference of the first ion exchange membrane roll and the diameter of the core was 21%, and the hardness was 92.

[0160] The first ion exchange membrane roll body was set in a slitting device, and while being discharged at a conveyance speed of 3 m / min, the width was cut to 420 mm and wound, thereby producing a second ion exchange membrane roll body having a length L of ion exchange membrane of 100 m (100,000 mm). The core used was an ABS resin core having an inner diameter of 76 mm, a wall thickness of 8 mm, and a width of 600 mm. A proximity roller was used at the time of winding, and the winding tension was 10 N / m. In addition, as the tension control device, a tension adjusting roller was used, and a relaxing roller was provided just before the slitting position. There was no shaking or relaxation of the film at the time of slitting, and the tension and the conveyance speed were stable, and no variation was observed.

[0161] <Examples 2 to 7>

[0162] In the slitting device, the cut width, the wound length, the conveyance speed, and the winding tension were changed as shown in Table 1, and otherwise, the second ion exchange membrane roll body was produced in the same manner as in Example 1.

[0163] <Comparative Example 1>

[0164] In the slitting device, a contact roller was used in the winding section, and otherwise, the second ion exchange membrane roll body was produced in the same manner as in Example 1.

[0165] <Example 8>

[0166] The first ion exchange membrane roll body produced in Example 2 was set in a small slitting device, and slitting was performed at a width of 130 mm, thereby obtaining a second ion exchange membrane roll body. A proximity roller was used at the time of slitting, and the conveyance speed was 3 m / min, and the winding tension was 10 N / m. There was no shaking or relaxation of the film at the time of slitting, and the tension and the conveyance speed were stable, and no variation was observed

[0167] The obtained second ion exchange membrane roll body was wound using an ABS core having an inner diameter of 10 mm, a wall thickness of 2.5 mm, and a width of 200 mm as the core, at a conveyance speed of 0.75 m / min, and at a winding tension of 9 N / m, thereby obtaining a third ion exchange membrane roll body having a length L of ion exchange membrane of 5 m (5,000 mm). A proximity roller and a contact roller were not used at the time of winding, and only the tension control of the unwinding section and the winding section was performed. There was no shaking or relaxation of the film at the time of winding, and it was stable.

[0168] <Examples 9 to 11, Comparative Examples 2 and 3>

[0169] A third ion exchange membrane roll body was obtained in the same manner as in Example 8, except that the winding tension and the conveyance speed were changed as shown in Table 2.

[0170] (Example 12)

[0171] After obtaining the ion exchange membrane roll body in the wet state as in Example 1, the ion exchange membrane roll body in the wet state was unwound, and hot air at 30°C was blown in the conveyance section after the unwinding, whereby the ion exchange membrane was dried. The membrane after the drying was conveyed to a winding section, and was wound around a core made of ABS resin having an inner diameter of 153 mm, a wall thickness of 7.5 mm, and a width of 1200 mm, to produce an ion exchange membrane roll body in the dry state. The conveyance speed at this time was 1 m / min, and the winding tension was 25 N / m. At the winding, a device of the center drive system in which there were no contact rollers and proximity rollers and only the tension was controlled was used. The length of the first ion exchange membrane roll body obtained was 398 m, and the circumference was 711 mm. The average thickness of the ion exchange membrane in the dry state obtained was 28 μm. In addition, the air layer ratio calculated from the circumference of the first ion exchange membrane roll body and the diameter of the core was 38%, and the hardness was 82.

[0172] The first ion exchange membrane roll body was set to a slitting device, was unwound at a conveyance speed of 5 m / min, was cut in the width to 414 mm, and was wound, whereby a second ion exchange membrane roll body was produced, the length L of the ion exchange membrane of which was 386 m (386,000 mm). The core used was a core made of ABS resin having an inner diameter of 153 mm, a wall thickness of 7.5 mm, and a width of 600 mm. At the winding, no contact roller was used, a proximity roller was used, and the winding tension was 24 N / m. In addition, as the tension control device, a slack adjusting roller was used, and a spreader roller was provided just before the slitting position. There was no shaking or slack of the film at the slitting, and the tension and the conveyance speed were stable, and no variation was observed.

[0173] <Assessment Test>

[0174] (Thickness d of Ion Exchange Membrane)

[0175] The ion exchange membrane was unwound from the ion exchange membrane roll body, and the film thickness was measured at 10 points in the width direction at equal intervals, and the average value thereof was taken as the average thickness d of the ion exchange membrane. A contact type thickness gauge (ID-H0530 manufactured by Mitutoyo Corporation) was used in the measurement. The results are shown in Tables 1 and 2.

[0176] (Measurement of Air Layer Ratio)

[0177] The air layer ratio was measured for the second ion exchange membrane roll bodies obtained in Examples 1 to 7, Example 12, and Comparative Example 1, and the third ion exchange membrane roll bodies obtained in Examples 8 to 11, Comparative Examples 2 and 3, by the following method. The results are shown in Table 3 and Table 4.

[0178] At 10 points set at equal intervals in the direction of the winding axis of the ion exchange membrane roll, the circumference of the ion exchange membrane roll was measured using a tape measure, and the average value thereof was taken as the length Bc (mm) of the circumference of the ion exchange membrane roll.

[0179] The obtained Bc (mm) was divided by the number π 3.14, and thus the diameter Bl (mm) was calculated, and the cross-sectional area Ba (mm 2 ).

[0180] Ba = (Bl 2 × 3.14) / 4

[0181] Next, the cross-sectional area Ca (mm) of the core portion was calculated from the diameter Cl (mm) of the core used, by the following formula.

[0182] Ca = (Cl 2 × 3.14) / 4

[0183] Here, the diameter of the core can be calculated from the inner diameter + wall thickness x 2 when the inner diameter and the wall thickness are known, and the diameters of both end portions can be measured using a tape measure when measured, and the average value thereof can be used.

[0184] The cross-sectional area Aa of the ion exchange membrane portion was calculated using Ba - Ca. From the obtained Aa, the air layer rate was calculated based on the following formula.

[0185] Air layer rate (%) = (Aa - dL) / Aa x 100

[0186] (Measurement of hardness)

[0187] A hardness tester of the ASKER Hardness Tester C type manufactured by Kobunshi Keiki Co., Ltd. was used to measure the value after the hardness tester was pressed vertically against the top surface of the ion exchange membrane roll so as to be in close contact. The measurement was performed at 10 points set at equal intervals in the length along the winding axis direction except for 20 mm of both end portions in the direction of the winding axis of the ion exchange membrane roll, and the average value thereof was taken as the hardness of the ion exchange membrane roll. The results are shown in Tables 3 and 4.

[0188] (Blocking test)

[0189] The second ion exchange membrane roll obtained in Examples 1 to 7, Example 12, and Comparative Example 1, and the third ion exchange membrane roll obtained in Examples 8 to 11, Comparative Examples 2 and 3 were evaluated for blocking by the following method. The results are shown in Table 5 and Table 6.

[0190] First, the ion exchange membrane roll body was held at both ends of the roll core so that the roll body floated in the hollow, and was left to stand in a high-temperature high-humidity tank at 50°C and 80% relative humidity for 20 hours. As a pretreatment for the test, the outermost 1 -turn portion of the ion exchange membrane was peeled off from the end of the short side of the ion exchange membrane located at the outermost periphery of the ion exchange membrane roll body after the standing. The circumference of the ion exchange membrane roll body from which the outermost 1 -turn portion was peeled off was measured using a tape measure at 10 points set at equal intervals in the roll axis direction of the ion exchange membrane, and the average value thereof was taken as Q (mm). Next, the roll core was held at both ends with the end of the short side as the apex of the roll body, and the ion exchange membrane roll body was set in a simple unwinding machine. Then, the roll body was rotated 1 turn with the end as the starting point. After the rotation of 1 turn, the point at which the ion exchange membrane at the outermost periphery was in contact with the ion exchange membrane roll body was taken as the peeling point. The length of the circular arc of the portion in which the ion exchange membrane at the outermost periphery was in contact with the ion exchange membrane roll body from the apex of the roll body to the peeling point was measured using a tape measure at 10 points set at equal intervals in the roll axis direction of the ion exchange membrane, and the average value thereof was taken as q (mm).

[0191] Using the obtained Q and q, the angle θ (°) of the portion in which the ion exchange membrane at the outermost periphery was in contact with the ion exchange membrane roll body was calculated by the following formula.

[0192] θ = 360 x (q / Q)

[0193] From the obtained θ, the state of the adhesion was determined by the following criteria. The results thereof are shown in Tables 5 and 6.

[0194] O: θ was 90° or more and less than 135°.

[0195] X: In the peeling-off of the outermost periphery in the pretreatment, peeling-off was not possible due to the close adhesion, or θ was 135° or more.

[0196] If no adhesion at all occurred, the ion exchange membrane at the outermost periphery fell downward due to the weight thereof when the ion exchange membrane roll body was rotated, and thus the angle became 90°.

[0197] (Winding displacement test)

[0198] The distance from the end of the roll core to the end of the ion exchange membrane was measured using a ruler at one end surface of the ion exchange membrane roll body. The ion exchange membrane roll body was hung in a high-temperature high-humidity tank in a state in which the roll core was held at both ends with the measured end surface as the lower side and inclined at an angle of 4° from the horizontal surface, and was left to stand in an atmosphere at 50°C and 80% relative humidity for 20 hours. After the standing, the distance from the end of the roll core to the end of the ion exchange membrane was measured using a ruler at the end surface of the ion exchange membrane roll body on the lower side, and the result of the winding displacement test was determined according to the difference from the initial distance according to the following criteria. The results thereof are shown in Tables 5 and 6.

[0199] O: The difference between the initial distance and the distance after standing was 0 mm or more and less than 2 mm.

[0200] A: The difference between the initial distance and the distance after standing was 2 mm or more and less than 4 mm.

[0201] X: The difference between the initial distance and the distance after standing was 4 mm or more.

[0202] <Appearance Evaluation of Ion Exchange Membrane Winding Body>

[0203] The appearance of the second ion exchange membrane winding bodies obtained in Examples 1 to 7, Example 12, and Comparative Example 1, and the third ion exchange membrane winding bodies obtained in Examples 8 to 11, Comparative Examples 2 and 3, was evaluated immediately after production as follows. The results are shown in Table 5 and Table 6.

[0204] 1. Wrinkle

[0205] The ion exchange membrane winding body surface was visually evaluated for the presence or absence of wrinkles.

[0206] O: No wrinkles were generated on the winding body surface.

[0207] X: Wrinkles were generated on the winding body surface.

[0208] 2. Shift

[0209] The end surface of the ion exchange membrane winding body was observed, and the shift was determined according to the following criteria.

[0210] O: The protrusion amount of the ion exchange membrane from the winding body end surface was 0 mm or more and less than 2 mm.

[0211] A: The protrusion amount of the ion exchange membrane from the winding body end surface was 2 mm or more and less than 4 mm.

[0212] X: The protrusion amount of the ion exchange membrane from the winding body end surface was 4 mm or more.

[0213] [Table 1]

[0214]

[0215] [Table 2]

[0216]

[0217] [Table 3]

[0218]

[0219] [Table 4]

[0220]

[0221] [Table 5]

[0222]

[0223] [Table 6]

[0224]

[0225] Legend

[0226] 1…ion exchange membrane, 2…core, 3…ion exchange membrane section, 10…ion exchange membrane roll body, 100…polymerizable composition impregnating device, 101…unwinding section, 102…conveying section, 103…winding section, 104…nip roller, 105…conveying roller, 106…conveying roller, 107…conveying roller, 300…ion exchange membrane roll body manufacturing device, 301…unwinding section, 302…conveying section, 303…winding section, 304…tension cutting mechanism, 305…conveying roller, 306…approach roller, Aa…area of ion exchange membrane section, Bc…circumference of ion exchange membrane roll body, Bl…diameter of ion exchange membrane roll body, Br…radius of ion exchange membrane roll body, Bw…length of ion exchange membrane roll body in winding axis direction, Ca…area of core, Cc…circumference of core, Cl…diameter of core, Cr…radius of core, Cw…length of core in winding axis direction, d…thickness, L…length of first side, PC…polymerizable composition, T…tank, W…length of second side.

Claims

1. An ion exchange membrane roll, comprising: a planar ion exchange membrane in a dry state having a first side and a second side, the planar ion exchange membrane being wound with a winding axis parallel to the second side, the second side being perpendicular to the first side and having a length equal to or less than the first side; The air layer ratio of the ion exchange membrane wound body represented by the following formula (I) is greater than 5% and less than 50%: Air layer rate (%) = (Aa-dL) / Aa×100 (I) In the formula (I), Aa is the average area of ​​the cross section of the ion exchange membrane in the wound body perpendicular to the winding axis direction, d is the average thickness of the ion exchange membrane, L is the length of the first side of the ion exchange membrane.

2. The ion exchange membrane wound body according to claim 1, wherein The air layer ratio is greater than or equal to 7% and less than or equal to 38%.

3. The ion exchange membrane wound body according to claim 1, wherein The hardness measured by a durometer (ASKER durometer type C) is 80 or more and 95 or less. The ion exchange membrane wound body according to claim 1 , wherein: The average thickness d of the ion exchange membrane is 10 μm or more and 200 μm or less. The ion exchange membrane wound body according to claim 1 , wherein: A ratio Br / d of a radius Br of the cross section of the ion exchange membrane wound body to an average thickness d of the ion exchange membrane is 450 or more and 12000 or less. The ion exchange membrane wound body according to claim 1 , wherein: The ion exchange membrane includes a porous substrate and an ion exchange resin supported on the porous substrate.

7. The ion exchange membrane wound body according to claim 6, wherein The ion exchange resin includes at least one ion exchange group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, and an imidazolium group.

8. The ion exchange membrane wound body according to claim 6, wherein The porous substrate includes a polyolefin-based resin. 9 . The ion exchange membrane wound body according to claim 1 , which has a cylindrical shape. 10 . The ion exchange membrane wound body according to claim 1 , further comprising a winding core, wherein the ion exchange membrane is wound around the winding core. The ion exchange membrane wound body according to claim 1 , wherein: A ratio Br / Cr of a radius Cr of the winding core to a radius Br of the cross section of the ion exchange membrane wound body is 1.1 or more and 3.3 or less.

12. A method for producing an ion exchange membrane wound body comprising a winding core and a dry ion exchange membrane wound around the winding core, the method comprising: The step of conveying the dry ion exchange membrane to the winding core at a conveying speed of 0.75 m / min to 30 m / min; as well as The step of winding the dry ion exchange membrane around the winding core at a winding tension of 3 N / m or more and 100 N / m or less, The dry ion exchange membrane is wound around the core in a manner that does not apply pressure to the core or a surface of the dry ion exchange membrane wound around the core.

13. The manufacturing method according to claim 12, wherein: The winding tension is 5 N / m or more and 50 N / m or less.

14. The manufacturing method according to claim 12, wherein: The conveying speed is 3 m / min or more and 30 m / min or less.

15. The manufacturing method according to claim 12, wherein: A ratio Br / Cr of a radius Cr of the winding core to a radius Br of a cross section of the ion exchange membrane wound body perpendicular to the winding axis direction is 1.1 or more and 3.3 or less.

16. The manufacturing method according to claim 12, wherein: The ion exchange membrane includes a porous substrate and an ion exchange resin supported on the porous substrate.

17. The manufacturing method according to claim 16, wherein: The ion exchange resin includes at least one ion exchange group selected from the group consisting of a quaternary ammonium group, a pyridinium group, a triazolium group, and an imidazolium group.

18. The manufacturing method according to claim 16, wherein: The porous substrate includes a polyolefin-based resin.

19. The manufacturing method according to claim 12, further comprising: The step of drying the wet ion exchange membrane to obtain the dried ion exchange membrane.

20. The manufacturing method according to claim 19, further comprising: a step of supporting a curable composition containing an ion exchange resin precursor on a porous substrate to obtain a structure; a step of curing the curable composition of the structure to obtain an ion exchange membrane precursor; as well as A step of introducing ion exchange groups into the ion exchange membrane precursor to obtain the wet ion exchange membrane.

21. A method for manufacturing an ion exchange sheet, comprising: a step of unwinding the ion exchange membrane from the ion exchange membrane wound body according to claim 1 or the ion exchange membrane wound body obtained by the method according to claim 12; as well as The step of cutting the unrolled ion exchange membrane.

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