JP7516783B2 - Composite polymer electrolyte membrane roll - Google Patents

Description

The present invention relates to a roll of a polymer electrolyte membrane that is a composite of a polymer electrolyte membrane and a porous substrate.

It is known that solid polymer electrolyte membranes used in solid polymer electrolyte fuel cells and the like are combined with a porous substrate to enhance durability.
As a method for producing the above-mentioned composite polymer electrolyte membrane, for example, a method has been proposed in which a polymer electrolyte solution is applied to a substrate film, a porous substrate is placed on top of the substrate and impregnated with the polymer electrolyte solution, and then the polymer electrolyte solution is applied to the other surface of the porous substrate (Patent Documents 1 to 4).

The document also describes that these manufacturing steps are carried out using a roll-to-roll method. In other words, a long roll of substrate film is unwound, a polymer electrolyte solution is applied to it, a porous substrate is placed on top of it, and the polymer electrolyte solution is applied to the other surfaces of the porous substrate in a dry or wet state, which is then dried and wound into a roll.

JP 2004-356075 A JP 2006-202532 A JP 2015-76201 A JP 2019-186183 A

In the above manufacturing process, the first electrolyte layer and the second electrolyte layer, which are laminated on both sides of the porous substrate, are usually laminated so as to cover the porous substrate in order to allow the electrolyte to penetrate and impregnate the porous substrate (e.g., FIG. 6). The rolled product of the composite polymer electrolyte membrane obtained by this manufacturing method has multiple layers (the first electrolyte layer, the porous substrate, and the second electrolyte layer) laminated on the substrate, so that the ends in the width direction tend to be partially raised (e.g., FIG. 7). If the ends of the rolled product are partially raised, wrinkles may occur, post-processing may not be performed stably, and quality may be deteriorated.

The object of the present invention is to provide a roll of a composite polymer electrolyte membrane in which swelling at the widthwise ends is suppressed.

The above object of the present invention can be achieved by the following invention.
[1] A roll of a composite polymer electrolyte membrane having, on a long strip-shaped substrate film, a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte, in that order, wherein the width direction length (W3) of the third layer is smaller than the width direction length (W2) of the second layer.
[2] A roll of a composite polymer electrolyte membrane having, on a long strip-shaped substrate film, a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte, in that order, wherein, in a width direction thickness profile of the third layer, the average thickness (Te) of both end regions is smaller than the average thickness (Tc) of a central region.

The present invention provides a roll of a composite polymer electrolyte membrane in which swelling at the widthwise ends is suppressed.

FIG. 1 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to one embodiment of the first invention of the present invention. FIG. 2 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to another embodiment of the first invention. FIG. 2 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to another embodiment of the first invention. FIG. 4 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to one embodiment of the second invention of the present invention. FIG. 11 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to another embodiment of the second invention. FIG. 1 is a schematic cross-sectional view in the width direction of a conventional composite polymer electrolyte membrane. FIG. 1 is a front schematic view of a roll of a conventional polymer electrolyte membrane composite. FIG. 1 is a schematic diagram of one embodiment of a process for continuously producing a roll-shaped product of the present invention by a roll-to-roll method. FIG. 2 is a schematic diagram showing another embodiment of a process for continuously producing the roll-shaped material of the present invention by a roll-to-roll method.

The composite polymer electrolyte membrane roll of the present invention has a configuration (basic configuration) in which a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte are arranged in that order on a long strip-shaped substrate film. Hereinafter, the composite polymer electrolyte membrane roll may be simply referred to as a "roll", and the long strip-shaped substrate film may be referred to as the "substrate film", the first layer containing a polymer electrolyte as the "first layer", the second layer containing a porous substrate as the "second layer", and the third layer containing a polymer electrolyte as the "third layer".

The first invention of the present invention is characterized in that, in the above basic configuration, the widthwise length (W3) of the third layer is smaller than the widthwise length (W2) of the second layer. Also, the second invention of the present invention is characterized in that, in the above basic configuration, in the widthwise thickness profile of the third layer, the average thickness (Te) of both end regions is smaller than the average thickness (Tc) of the central region.

[First Invention]
1 is a schematic cross-sectional view in the width direction of one unit of a roll of a composite polymer electrolyte membrane according to one embodiment of the first aspect of the present invention, in which the base film, the first layer, the second layer, and the third layer are each constituted by a single layer, and the roll is formed by winding up the above-mentioned one unit.

Each unit 1 of the roll has a first layer 11, a second layer 12 and a third layer 13 on a base film 10. The width direction length W3 of the third layer 13 is smaller than the width direction length W2 of the second layer 12.
The widthwise length W3 of the third layer 13 can be controlled, for example, by adjusting the coating width. From the viewpoint of suppressing swelling at the ends of the roll-shaped material, it is preferable to adjust W3 so that an uncoated area A exists at each of both ends in the widthwise direction of the second layer. The uncoated areas A at both ends in the widthwise direction of the third layer are preferably 1 to 30 mm, more preferably 2 to 20 mm, and particularly preferably 3 to 15 mm.

In other words, the relationship between the widthwise length W3 of the third layer 13 and the widthwise length W2 of the second layer 12 is preferably 2 mm ≦ W2 - W3 ≦ 60 mm, more preferably 4 mm ≦ W2 - W3 ≦ 40 mm, and particularly preferably 6 mm ≦ W2 - W3 ≦ 30 mm.

The relationship between the substrate, the first layer, and the second layer is not particularly limited, but the relationship shown in FIG. 1 is preferable. That is, it is preferable that the widthwise length W1 of the first layer is smaller than the widthwise length W0 of the substrate film, and the widthwise length W2 of the second layer is smaller than the widthwise length W1 of the first layer. The relationship between W1 and W0 and the relationship between W2 and W1 can be the same as the relationship between W3 and W2 described above. By adopting such a relationship, it is possible to further suppress the swelling of the ends of the roll-shaped material.

2 and 3 are schematic cross-sectional views of other embodiments of the first invention. Fig. 2 shows an embodiment in which the widthwise lengths of the first layer 11 and the second layer 12 are approximately the same and are shorter than the widthwise length of the base film 10. The relationship between the third layer and the second layer is the same as in the embodiment of Fig. 1.
3 shows an embodiment in which the width direction lengths of the base film, the first layer and the second layer are approximately the same. The relationship between the third layer and the second layer is the same as in the embodiment in FIG.

[Second Invention]
4 is a schematic cross-sectional view in the width direction of one unit of a roll of a polymer electrolyte membrane composite according to an embodiment of the second aspect of the present invention. One unit 2 of the roll has a base film 20, a first layer 21, a second layer 22 and a third layer 23 on the base film 20.

In the thickness profile in the width direction of the third layer 23, the average thickness (Te) of both end regions E is smaller than the average thickness (Tc) of the central region C. Here, the length of each of the end regions E is 20 mm. The length of the central region C is obtained by subtracting the lengths of both end regions E from the width direction length W3 of the third layer 23, that is, C=W3-E×2.
The average thickness (Te) of the end region E is the average of measurements taken at three points spaced 5 mm apart from the end to the inside. The average thickness (Tc) of the central region C is the average of measurements taken at three points spaced equally apart. The thicknesses can be measured by observing the cross section with a scanning electron microscope (SEM).

From the viewpoint of suppressing swelling at both ends of the roll-shaped material, the average thickness (Te) of the end region E is preferably 90% or less, more preferably 70% or less, and particularly preferably 50% or less of the average thickness (Tc) of the central region C. The feasible lower limit is about 10%.
Methods for making the average thickness (Te) of the end region E smaller than the average thickness (Tc) of the central region C include (a) a method of suctioning or removing a portion of the coating liquid in the end region with a knife before applying and drying the third layer, (b) a method of relatively reducing the width of the coating liquid ejection slit in the end region of the slit die coater, (c) a method of relatively reducing the amount of coating liquid supplied to the end region of the slit die coater, and (d) a method of coating using a kiss method (a method in which a backup roller is not provided) using a slit die coater, and in the present invention, method (d) is preferably used.

Figure 4 shows an embodiment in which the widthwise length W3 of the third layer 23 and the widthwise length W2 of the second layer 22 are roughly the same, but as shown in Figure 5, W3 may be smaller than W2. In other words, Figure 5 shows an embodiment of the invention that combines the first and second inventions, and can further suppress swelling at both ends of the roll-shaped material.

In the second invention and the invention combining the first and second inventions, the relationship between the base film 20, the first layer 21, and the second layer 22 is not particularly limited, but is preferably as shown in Figures 4 and 5, i.e., the relationship described in the embodiment of Figure 1, which is the first invention.

In addition, in the second invention and the invention combining the first and second inventions, the relationship between the base film 20, the first layer 21, and the second layer 22 may be the same as that shown in Figures 2 and 3 above.

[Basic configuration]
The basic structure of the roll-shaped product of the present invention is a long strip-shaped substrate film having, in this order, a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte. Each of the components will be described in detail below.

[Base film]
The substrate film is preferably one having chemical resistance to the polymer electrolyte solution and heat resistance to drying temperatures, and examples of the material for such a substrate film include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, polycarbonate, polyetherimide, polyphenylene sulfide, polyimide, polystyrene, etc. Among these, polyesters are preferred from the viewpoints of chemical resistance and heat resistance, and polyethylene terephthalate is particularly preferred.
The base film may be subjected to a release treatment, a mirror finish, an embossing treatment, a matte finish or the like, as required.
The thickness of the substrate film is preferably from 30 to 300 μm, more preferably from 50 to 200 μm, and particularly preferably from 70 to 150 μm.

[First layer containing polyelectrolyte]
The polymer electrolyte contained in the first layer is not particularly limited, and may be a known polymer electrolyte used in a solid polymer electrolyte membrane constituting a fuel cell. Examples of such a polymer electrolyte include a perfluoro-based polymer having an ionic group and a hydrocarbon-based polymer having an ionic group.

A perfluoropolymer having ionic groups means a polymer in which most or all of the hydrogen atoms in the alkyl and/or alkylene groups in the polymer have been replaced with fluorine atoms. Representative examples of perfluoropolymers having ionic groups include commercially available products such as Nafion (registered trademark) (manufactured by DuPont), Flemion (registered trademark) (manufactured by Asahi Glass Co., Ltd.), and Aciplex (registered trademark) (manufactured by Asahi Kasei Corporation).

As the hydrocarbon polymer having an ionic group, an aromatic hydrocarbon polymer having an aromatic ring in the polymer main chain is more preferable. Specific examples of aromatic hydrocarbon polymers include polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymer, polyarylene ketone, polyether ketone, polyarylene phosphine oxide, polyether phosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, and polyimide sulfone, and a polymer having a structure selected from the group consisting of aromatic rings and polyimide sulfone in the main chain. In addition, polysulfone, polyethersulfone, polyetherketone, etc., as used herein, are general terms for structures having sulfone bonds, ether bonds, and ketone bonds in their molecular chains, and include polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone, polyetherketoneetherketoneketone, polyetherketonesulfone, etc. The hydrocarbon skeleton may have a plurality of these structures. Among these, polymers having a polyetherketone skeleton, i.e., polyetherketone-based polymers, are most preferred as aromatic hydrocarbon-based polymers.

The ionic group used herein can preferably be one or more selected from the group consisting of a sulfonic acid group (-SO ₂ (OH)), a sulfate group (-OSO ₂ (OH)), a sulfonimide group (-SO ₂ NHSO ₂ R (R represents an organic group)), a phosphonic acid group (-PO(OH) ₂ ), a phosphate group (-OPO(OH) ₂ ), a carboxylate group (-CO(OH)), and metal salts thereof. Of these, it is more preferable to have at least a sulfonic acid group, a sulfonimide group, a sulfate group, or a phosphonic acid group from the viewpoint of high proton conductivity, and it is most preferable to have at least a sulfonic acid group from the viewpoint of hydrolysis resistance.

During the coating and film formation of the first layer and the second layer, in order to reduce the inclusion of impurities due to the material of the coating device and the decomposition of the ionic groups due to heating, it is preferable to introduce these ionic groups as metal salts. In this case, by contacting with an acidic solution after film formation, the metal salt can be replaced with a proton and converted into an ionic group. The metal that forms the metal salt may be any metal that can form a salt with the ionic group. From the standpoint of cost and environmental load, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W, etc. are preferable, and among these, Li, Na, K, Ca, Sr, Ba are more preferable, and Li, Na, and K are even more preferable. The introduction of the ionic group into the electrolyte membrane may be performed by a method of introducing a metal salt or derivative of the ionic group into the polymer after polymerization, or may be performed by a method of introducing a metal salt of the ionic group into a monomer and then polymerizing the monomer.

The first layer may further contain additives such as a crosslinking agent or a crystallization nucleating agent used in a typical polymer compound, a plasticizer, a stabilizer, a release agent, an antioxidant, a radical scavenger, and inorganic fine particles, for the purposes of improving the mechanical strength, the thermal stability of the ionic group, the water resistance, the solvent resistance, the radical resistance, the coatability of the coating liquid, and the storage stability.
The dry thickness of the first layer is preferably from 0.5 to 20 μm, more preferably from 1 to 15 μm, and particularly preferably from 2 to 10 μm.

[Second layer comprising a porous substrate]
The form of the porous substrate contained in the second layer may be a woven fabric, a nonwoven fabric, a porous film, etc. Among these, a nonwoven fabric and a porous film are preferred, and a porous film is particularly preferred.
The material for the porous substrate is not particularly limited as long as it does not block or impede proton conduction. From the viewpoints of heat resistance and physical strength, however, aliphatic polymers, aromatic polymers, and fluorine-containing polymers are preferably used.
Examples of aliphatic polymers include, but are not limited to, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers.

Examples of aromatic polymers include polyphenylene sulfide, polyether sulfone, polysulfide sulfone, polyethylene terephthalate, polycarbonate, polyimide, polyetherimide, polyether ketone, polyether ether ketone, polyphenylene oxide, aromatic polyamide, and polyamideimide.
Examples of fluorine-containing polymers include polytetrafluoroethylene (PTFE), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene difluoride (PVDF), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy fluorine resin (PFA), and ethylene chlorotrifluoroethylene copolymer (ECTFE).

Among the above-mentioned materials for the porous substrate, fluorine-containing polymers are preferred, and from the viewpoint of water resistance, PTFE, polyhexapropylene, FEP, and PFA are more preferred, with PTFE being more preferred since it has high mechanical strength due to its molecular orientation.

As the porous substrate in the present invention, a porous film of PTFE is particularly preferred. The porous film of PTFE can be obtained by stretching. In addition, commercially available stretched porous films of PTFE, such as Tetratex (registered trademark of Donaldson Co.) and Gore-Tex (registered trademark of Japan Gore-Tex), can be used.

The porosity of the porous substrate is not particularly limited, but from the viewpoint of achieving both proton conductivity and mechanical strength of the resulting composite polymer electrolyte membrane, it is preferably 50 to 98%, more preferably 60 to 95%, and particularly preferably 70 to 93%. The porosity of the porous substrate (Y1: volume %) is defined as the value calculated by the following formula.

Y1=(1-Db/Da)×100
Da: specific gravity of the polymer constituting the fluorine-containing polymer porous substrate. Db: specific gravity of the entire fluorine-containing polymer porous substrate.

The average pore size of the porous substrate is preferably 0.01 to 5 μm, more preferably 0.02 to 3 μm, and particularly preferably 0.05 to 1 μm. The average pore size of the porous substrate can be measured by the bubble point method (JIS K3832).

The thickness of the porous substrate is preferably from 1 to 100 μm, more preferably from 2 to 50 μm, and particularly preferably from 3 to 20 μm.
The pores of the porous substrate are preferably filled with a polymer electrolyte. The polymer electrolyte is preferably the polymer electrolyte contained in the first layer and/or the second layer.
The method for filling the porous substrate with the polymer electrolyte is not particularly limited, but a method in which the porous substrate is laminated and impregnated before the first layer applied onto the substrate film is dried is preferred. Details will be described later.

The thickness of the porous substrate is preferably 1 to 100 μm, more preferably 2 to 50 μm, and particularly preferably 3 to 20 μm. The thickness of the second layer including the porous substrate is preferably 1 to 100 μm, more preferably 2 to 50 μm, and particularly preferably 3 to 20 μm.
The second layer may further contain additives such as a crosslinking agent or a crystallization nucleating agent used in a typical polymer compound, a plasticizer, a stabilizer, a release agent, an antioxidant, a radical scavenger, and inorganic fine particles, for the purposes of improving the mechanical strength, the thermal stability of the ionic group, the water resistance, the solvent resistance, the radical resistance, the coatability of the coating liquid, and the storage stability.

[Polyelectrolyte-containing third layer]
The polymer electrolyte contained in the third layer may be the same as the polymer exemplified as the polymer electrolyte contained in the first layer. The polymer electrolyte in the third layer and the polymer electrolyte in the first layer may be the same or different, but are preferably the same.

The third layer may further contain additives such as a crosslinking agent or a crystallization nucleating agent typically used in a polymer compound, a plasticizer, a stabilizer, a release agent, an antioxidant, a radical scavenger, and inorganic fine particles, for the purposes of improving the mechanical strength, the thermal stability of the ionic group, the water resistance, the solvent resistance, the radical resistance, the coatability of the coating liquid, and the storage stability.
The dry thickness of the first layer is preferably from 0.5 to 20 μm, more preferably from 1 to 15 μm, and particularly preferably from 2 to 10 μm.

[Roll-shaped product]
The roll-shaped product of the present invention is a product obtained by winding up the above-mentioned basic structure. The width direction length of the long strip-shaped base film constituting the roll-shaped product is suitably 100 to 3000 mm, but from the viewpoints of productivity and quality stability, it is preferably 200 to 2500 mm, more preferably 500 to 2000 mm, and particularly preferably 700 to 1500 mm.

The strip length of the base film is preferably 50 to 3,000 m, but from the viewpoints of productivity and quality stability, it is preferably 100 to 2,500 m, more preferably 200 to 2,000 mm, and particularly preferably 300 to 1,500 mm.

The width direction length and band length of the base film determine the width direction length and winding length of the roll-shaped product.
The widthwise lengths of the first layer, the second layer, and the third layer laminated on the base film are appropriately set based on the widthwise length of the base film and on the first and second aspects of the present invention described above.

The rolled product of the composite polymer electrolyte membrane of the present invention can be subjected to acid treatment or water washing treatment for proton replacement or impurity removal, treatment (coating) for introducing the various additives described above into the composite polymer electrolyte membrane, or lamination of a catalyst layer, as necessary. These treatments and laminations are preferably performed by the roll-to-roll method. The rolled product of the present invention can be stably subjected to the above-mentioned post-processing because the swelling of the ends is suppressed.

The roll-shaped product of the present invention can be cut to an appropriate size and used as an electrolyte membrane in various applications, such as solid polymer fuel cells, electrochemical hydrogen pumps, and water electrolysis hydrogen generation devices.

[Method of manufacturing roll-shaped product]
An example of the method for producing the rolled product of the present invention will be described below, but the present invention is not limited thereto. Fig. 8 is a schematic diagram showing a process for continuously producing the rolled product of the present invention by a roll-to-roll method.

A long strip-shaped base film 100 supplied from a roll is unwound while being supported by an unwinder 120, and a coating liquid 101 for a first layer is applied to the base film 100 by a first coater 121.
As the first coating device, a slit die coater, a gravure coater, a bar coater, a roll coater, a doctor coater, a knife coater, a direct roll coater, a spray coater, a dip coater, a curtain coater, an extrusion coater, a spin coater, etc. Among these, a slit die coater is preferred, and it is further preferred to coat the base film 100 with the slit die coater while supporting it with a backup roller 122.

The porous substrate 102 is supplied on a roll, and is unwound while being supported by the unwinder 123. The porous substrate 102 is laminated to the surface of the substrate film 100 on which the coating liquid 101 of the first layer has been applied. The porous substrate 102 is impregnated with a portion of the coating liquid of the first layer, filling the pores of the porous substrate 102 to form a second layer. The remaining coating liquid that has not been impregnated forms the first layer. Therefore, the wet coating amount (wet thickness) when applying the first layer is appropriately set based on the amount impregnated into the porous substrate and the final design film thickness of the first layer.

The time from when the coating liquid 101 of the first layer is applied to the substrate film 100 until the porous substrate 102 is bonded is not particularly limited as long as the coating liquid 101 is maintained in a wet state, but from the viewpoint of improving productivity and reducing equipment size, it is preferably within 5 minutes, more preferably within 3 minutes, and particularly preferably within 2 minutes. The lower limit is about 5 seconds.

Next, the coating liquid 103 for the third layer is applied to the surface of the porous substrate 102 opposite the first layer by a second coating device 124. The second coating device may be the same as the first coating device, but a slit die coater is preferred, and it is preferable to coat the substrate film 100 with the slit die coater while supporting it with a backup roller 125.

The time from when the porous substrate 101 is bonded to the surface coated with the first layer to when the coating liquid 103 for the third layer is applied, i.e., the impregnation time, is preferably 10 seconds or more, more preferably 15 seconds or more, and particularly preferably 20 seconds or more, from the viewpoint of sufficiently filling the pores of the porous substrate 101 with the polymer electrolyte. Furthermore, from the viewpoint of improving productivity and reducing equipment size, the impregnation time is preferably 4 minutes or less, more preferably 3 minutes or less, and particularly preferably 2 minutes or less.

The coating liquid for the first layer (including the coating liquid impregnated in the porous substrate) may be dried before the third layer is applied, but it is preferable to apply the coating liquid for the third layer in a wet state. This improves power generation efficiency.

A part of the coating liquid of the third layer may or may not be impregnated into the porous substrate 102. When the coating liquid is impregnated, the third layer is formed with the remaining coating liquid that is not impregnated. Whether or not a part of the coating liquid of the third layer is impregnated into the porous substrate is influenced by the time from when the porous substrate is bonded to the first layer to when the third coating layer is applied (the impregnation time of the coating liquid of the first layer). In addition, due to the relationship between the concentration and permeability of the coating liquid of the first layer and the coating liquid of the third layer, the coating liquid of the third layer may be replaced and permeated near the surface of the porous substrate.
After the third layer is applied, it is dried in a drying oven 126 and wound into a roll by a winder 127 to obtain the roll-shaped product 110 of the present invention. The temperature of the drying oven 126 is preferably 50 to 150°C, more preferably 60 to 130°C, and particularly preferably 70 to 110°C.
Fig. 9 is a schematic diagram of another embodiment of the process for producing a roll-shaped material of the present invention. The process is generally the same as that of Fig. 8, except that the second coating device 124 is changed to a kiss type using a slit die coater. The kiss type is a method in which a backup roll is not arranged at a position opposite to the coating device with the substrate film sandwiched therebetween.
By applying the third layer by the kiss method using a slit die coater, the second aspect of the present invention can be realized, that is, "in the width direction thickness profile of the third layer, the average thickness (Te) of both end regions is smaller than the average thickness (Tc) of the central region. The mechanism behind this is unclear, but it is presumed to be due to the difference in the gap between both end regions and the central region.

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[Evaluation method]
(1) Measurement of the amount of swelling at the end of the rolled product The maximum diameter of the swelling at the end was determined from the outer periphery. Similarly, the average diameter of the central part was determined by measuring three equally spaced points. The amount of swelling at the end was determined by subtracting the average diameter at the central part from the maximum diameter of the swelling at the end.
(2) Measurement of the average thickness (Te) of the end region and the average thickness (Tc) of the central region of the third layer For a composite polymer electrolyte membrane in which a first layer, a second layer, and a third layer are laminated on a substrate film, measurements were taken at three points 5 mm apart from the outermost end in both end regions E of the third layer (regions up to 20 mm from the outermost end), and the average was taken as the average thickness of the end regions (Te). Similarly, measurements were taken at three points equally spaced apart in the central region C, and the average was taken as the average thickness of the central region (Tc). The thicknesses were determined by observing the cross section with a scanning electron microscope (SEM).

[Base film]
As the substrate film, a polyethylene terephthalate (PET) film ("Lumirror (registered trademark) T60, manufactured by Toray Industries, Inc.) having a thickness of 125 μm, a width direction length of 1000 mm, and a longitudinal length of 500 m was used.

[Polymer electrolyte]
As a polymer electrolyte, an aromatic hydrocarbon-based polymer having an ionic group (block copolymer b1) was synthesized in the following manner.

<Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP) represented by the following general formula (G1)>

49.5 g of 4,4'-dihydroxybenzophenone (DHBP), 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate were charged and dissolved in a 500 mL flask equipped with a stirrer, thermometer, and distillation tube. The mixture was then stirred and kept at 78-82°C for 2 hours. The internal temperature was then gradually raised to 120°C, and the mixture was heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling the reaction solution to room temperature, the reaction solution was diluted with ethyl acetate, the organic layer was washed with 100 mL of a 5% aqueous potassium carbonate solution, and the solvent was distilled off. 80 mL of dichloromethane was added to the residue to precipitate crystals, which were then filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane. GC analysis of the crystals revealed that they were 99.8% 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane and 0.2% 4,4'-dihydroxybenzophenone.

<Synthesis of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone represented by the following general formula (G2)>

109.1 g of 4,4'-difluorobenzophenone (Aldrich reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (Wako Pure Chemical Industries, Ltd. reagent) at 100°C for 10 hours. After that, it was gradually poured into a large amount of water, neutralized with NaOH, and then 200 g of salt was added to precipitate the compound. The resulting precipitate was filtered and recrystallized with an aqueous ethanol solution to obtain disodium-3,3'-disulfonate-4,4'-difluorobenzophenone represented by the above general formula (G2). The purity was 99.3%. The structure was confirmed by 1H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic substances) and ion chromatography (inorganic substances).

<Synthesis of oligomer a1 that does not contain an ionic group and is represented by the following general formula (G3)>

(In formula (G3), m represents a positive integer.)
In a 1000 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g of K-DHBP (100 mmol), and 20.3 g of 4,4'-difluorobenzophenone (Aldrich reagent, 93 mmol) were placed, and after nitrogen replacement, the mixture was dehydrated at 160 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, heated to remove toluene, and polymerized at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of methanol, and oligomer a1 (terminal OM group, M in the OM group represents Na or K, and the following notation follows this.) not containing ionic groups was obtained. The number average molecular weight was 10,000.

1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 20.0 g (2 mmol) of the oligomer a1 (terminal OM group) not containing an ionic group were placed in a 500 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap. After nitrogen replacement, the mixture was dehydrated at 100°C in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, heated to remove cyclohexane, and 4.0 g of decafluorobiphenyl (Aldrich reagent, 12 mmol) was placed and reacted at 105°C for 1 hour. The mixture was purified by reprecipitation with a large amount of methanol to obtain oligomer a1' (terminal fluoro group) not containing an ionic group represented by the formula (G3). The number average molecular weight was 11,000, and the number average molecular weight of oligomer a1 not containing an ionic group was calculated to be 10,400, minus the linker site (molecular weight 630).

<Synthesis of oligomer a2 containing an ionic group represented by the following general formula (G4)>

(In formula (G4), M represents Na or K.)
A 1000 mL three-neck flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap was charged with 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g of K-DHBP (50 mmol) and 9.3 g of 4,4'-biphenol (Aldrich reagent, 50 mmol), 39.3 g of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone (93 mmol), and 17.9 g of 18-crown-6 ether (Wako Pure Chemical Industries, 82 mmol), and after nitrogen substitution, 300 mL of N-methylpyrrolidone (NMP), 100 mL of toluene was dehydrated at 170 ° C., heated to remove toluene, and polymerized at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol, and an oligomer a2 (terminal OM group) containing an ionic group represented by the formula (G4) was obtained. The number average molecular weight was 16,000.

<Synthesis of block copolymer b1>
An oligomer a2 as a segment containing an ionic group, an oligomer a1 as a segment not containing an ionic group, and a polyketal ketone (PKK)-based block copolymer b1 containing octafluorobiphenylene as a linker moiety were synthesized as follows.

0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 16 g (1 mmol) of oligomer a2 (terminal OM group) containing ionic groups were placed in a 500 mL three-neck flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap. After nitrogen replacement, the mixture was dehydrated at 100°C in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, and the temperature was raised to remove the cyclohexane. 11 g (1 mmol) of oligomer a1' (terminal fluoro group) not containing ionic groups was added and reacted at 105°C for 24 hours. The mixture was purified by reprecipitation with a large amount of isopropyl alcohol to obtain block copolymer b1. The weight-average molecular weight was 280,000.

[Preparation of Coating Solution for First Layer]
22 parts of the block copolymer b1 obtained above was added to 80 parts of N-methyl-2-pyrrolidone (NMP) and stirred with a stirrer for 3 minutes to prepare a transparent coating liquid with a polymer concentration of 22% by mass.

[Porous substrate]
As the porous substrate constituting the second layer, an expanded porous PTFE film ("Tetratex" (registered trademark) AX-18 manufactured by Donaldson Co., Ltd., porosity: 85%) having a thickness of 6 μm and a length of 500 m was prepared.

[Coating solution for third layer]
The coating solution for the first layer was prepared in the same manner as for the first layer.

[Example 1]
Example 1 is an example of one embodiment of the first invention of the present invention. A roll of the composite polymer electrolyte membrane of the present invention was produced according to the production process of FIG. 8. Specifically, the coating solution of the first layer was applied to a substrate film with a wet thickness of 40 μm, and after 60 seconds, a porous substrate was laminated and impregnated for 30 seconds, and then the second layer was applied to a wet thickness of 40 μm, and after 30 seconds, the substrate was dried with hot air at 100° C. for about 10 minutes in a drying oven and wound up. The winding length of this roll was 500 m. The width direction lengths of each component are as follows:
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 960 mm
Width direction length W3 of the third layer: 940 mm
The amount of swelling at the ends of the rolled product produced above was 0.2 mm. Furthermore, the rolled product had a good wound appearance when visually observed, and no wrinkles were observed.

[Example 2]
Example 2 is an example of another embodiment of the first aspect of the present invention. It was manufactured in the same manner as Example 1, except that the width direction length of each component in Example 1 was changed as follows.
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 980 mm
Width direction length W3 of the third layer: 960 mm
The amount of swelling at the ends of the rolled product produced above was 0.4 mm. Furthermore, the rolled product had a good wound appearance when visually observed, and no wrinkles were observed.

[Example 3]
Example 3 is an example of one embodiment of the second invention of the present invention. A roll of the composite polymer electrolyte membrane of the present invention was produced according to the production process of FIG. 9. Specifically, the coating solution of the first layer was applied to a substrate film with a wet thickness of 40 μm, and after 60 seconds, a porous substrate was laminated and impregnated for 30 seconds, and then the second layer was applied to a wet thickness of 40 μm, and after 30 seconds, the substrate was dried with hot air at 100° C. for about 10 minutes in a drying oven and wound up. The winding length of this roll was 500 m. The width direction length of each component, and the average thickness (Te) of the end region and the average thickness (Tc) of the central region of the third layer are as follows.
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 960 mm
Width direction length W3 of the third layer: 960 mm
Average thickness of the end region of the third layer (Te): 2 μm
Average thickness (Tc) of the central region of the third layer: 5 μm
・(Te)/(Tc)×100=40%
The amount of swelling at the ends of the rolled product produced above was 0.4 mm. Furthermore, the rolled product had a good wound appearance when visually observed, and no wrinkles were observed.

[Example 4]
Example 4 is an example of another embodiment of the second aspect of the present invention. It was produced in the same manner as Example 3, except that the width direction length of each component in Example 3 was changed as follows.
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 980 mm
Width direction length W3 of the third layer: 980 mm
Average thickness of the end region of the third layer (Te): 2 μm
Average thickness (Tc) of the central region of the third layer: 5 μm
・(Te)/(Tc)×100=40%
The amount of swelling at the ends of the rolled product produced above was 0.8 mm. Furthermore, the rolled product had a good wound appearance when visually observed, and no wrinkles were observed.

[Example 5]
Example 5 is an example in which the first and second inventions of the present invention are combined. A roll of the composite polymer electrolyte membrane of the present invention was produced according to the production process of FIG. 9. Specifically, the coating solution of the first layer was applied to a substrate film with a wet thickness of 40 μm, and after 60 seconds, a porous substrate was laminated and impregnated for 30 seconds, and then the second layer was applied to a wet thickness of 40 μm, and after 30 seconds, the substrate was dried with hot air at 100° C. for about 10 minutes in a drying oven and wound up. The winding length of this roll was 500 m. The width direction length of each component, and the average thickness (Te) of the end region and the average thickness (Tc) of the central region of the third layer are as follows.
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 960 mm
Width direction length W3 of the third layer: 940 mm
Average thickness of the end region of the third layer (Te): 2 μm
Average thickness (Tc) of the central region of the third layer: 5 μm
・(Te)/(Tc)×100=40%
The amount of swelling at the ends of the rolled product produced above was 0.1 mm. Furthermore, the rolled product had an extremely good wound appearance when visually observed, and no wrinkles were observed.

[Comparative Example 1]
The manufacturing process was the same as in Example 1, except that the width direction lengths of the respective components in Example 1 were changed as follows.
・ Width direction length of base film W0: 1,000 mm
Width direction length W1 of the first layer: 980 mm
Width direction length W2 of the second layer (porous substrate): 980 mm
Width direction length W3 of the third layer: 980 mm
The amount of swelling at the ends of the rolled product produced as above was 2.5 mm. Furthermore, the rolled product had a poor wound appearance when visually observed, and the occurrence of wrinkles was also observed.

2: One unit of roll-shaped material 10, 20: Substrate film 11, 21: First layer containing polymer electrolyte
12, 22 Second layer comprising a porous substrate
13, 23 Second layer containing polyelectrolyte
30 Long strip-shaped substrate film 31 First electrolyte layer 32 Porous substrate 33 Second electrolyte layer 100 Substrate film 101 Coating liquid for first layer containing polymer electrolyte 102 Porous substrate 103 Coating liquid for third layer containing polymer electrolyte 110 Roll of composite polymer electrolyte membrane 120 Unwinder for roll of substrate film 121 First coating device 122 Backup roller for first coating device 123 Unwinder for roll of porous substrate 124 Second coating device 125 Backup roller for second coating device 126 Drying furnace 127 Winder for roll of composite polymer electrolyte membrane W0 Width direction length W1 of substrate Width direction length W2 of first layer containing polymer electrolyte Width direction length W3 of second layer containing base porous substrate Width direction length A of second layer containing base polymer electrolyte Uncoated portions C at both ends of second layer containing polymer electrolyte Central region E of second layer containing polymer electrolyte End regions of the second layer containing polyelectrolyte

Claims (6)

A roll of a composite polymer electrolyte membrane comprising a long strip-shaped substrate film and a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte, in that order, the first layer, the second layer, and the third layer each have an uncoated region at both ends in the width direction, the width direction length (W3) of the third layer is smaller than the width direction length (W2) of the second layer, the width direction length (W1) of the first layer is smaller than the width direction length (W0) of the substrate film, and the width direction length (W2) of the second layer is smaller than the width direction length (W1) of the first layer. A roll of a composite polymer electrolyte membrane comprising a long strip-like substrate film and a first layer containing a polymer electrolyte, a second layer containing a porous substrate, and a third layer containing a polymer electrolyte, in that order, the third layer having a width direction length (W3), a central region of the third layer having a width direction length (C), and both end regions in the width direction of the third layer having width direction length (E), the lengths of both end regions (E) are each 20 mm, the length of the central region (C) is (W3) minus the lengths of both end regions (E) (C=W3-E×2), and in a width direction thickness profile of the third layer, the average thickness (Te) of both end regions (E) is smaller than the average thickness (Tc) of the central region (C) . 2. The roll-shaped composite polymer electrolyte membrane according to claim 1, wherein the width direction length of the third layer is (W3), the central region of the third layer is (C), and both end regions in the width direction of the third layer are (E), the lengths of both end regions (E) are 20 mm, the length of the central region (C) is (W3) minus the lengths of both end regions (E), respectively (C=W3-E×2), and in a width direction thickness profile of the third layer, an average thickness (Te) of both end regions (E) is smaller than an average thickness (Tc) of the central region (C) . The roll-shaped composite polymer electrolyte membrane according to claim 2, characterized in that the width direction length (W1) of the first layer is smaller than the width direction length (W0) of the base film, and the width direction length (W2) of the second layer is smaller than the width direction length (W1) of the first layer. A roll of a composite polymer electrolyte membrane according to any one of claims 1 to 4, wherein the polymer electrolyte contained in the first layer and the third layer is an aromatic hydrocarbon-based polymer having an ionic group. A roll of composite polymer electrolyte membrane according to any one of claims 1 to 5, wherein the porous substrate is a porous film of polytetrafluoroethylene (PTFE).

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