JP2021170458A - Separation membrane support for electrochemical element - Google Patents

Abstract

To provide a separation membrane support for an electrochemical element, having excellent handleability such that an electrochemical element having excellent power generation performance can be easily provided.SOLUTION: It has been found that a fiber aggregate composed of fibers containing a nonionic surfactant is less likely to be charged and has excellent handleability. Therefore, a separation membrane support comprising the fiber aggregate is also less likely to be charged and has excellent handleability, and consequently, a thin separation membrane can be easily provided, and an electrochemical element having excellent power generation performance can be easily provided. Further, according to the present invention, even a separation membrane support which comprises a fiber aggregate composed of fibers including a resin having a resin moisture content of 2.0 mass% or less and is more easily charged, can prevent unintentional lowering of power generation performance of an electrochemical element and also enables an electrochemical element having excellent power generation performance to be easily provided.SELECTED DRAWING: None

Description

The present invention relates to a separation membrane support for an electrochemical device.

In recent years, the development of electrochemical elements such as fuel cells has become active. Since it is possible to provide an electrochemical element that has been made thinner in the development and an electrochemical element that has excellent power generation performance such as low internal resistance, a separation film (for example, an electrolyte film in a fuel cell) provided between both electrodes of the electrochemical element can be provided. , A polymer electrolyte film for a solid battery) is required to have a thin separation film (hereinafter, may be referred to as a thin film). However, since a thin separation membrane is inferior in shape stability during handling, shape stability in the manufacturing process of the electrochemical element, and dimensional stability during use of the electrochemical element, the separation membrane is supported by a fiber assembly or the like. Attempts have been made to reinforce with the body.
As such a separation membrane support, for example, as disclosed in Japanese Patent Application Laid-Open No. 2016-058152 (Patent Document 1), a fiber aggregate such as an electrostatically spun non-woven fabric having a small average fiber diameter is adopted. Has been considered.

Japanese Unexamined Patent Publication No. 2016-058152 (Claims, 0039, etc.)

The inventors of the present application have studied a thin fiber aggregate capable of forming a separation membrane support in order to provide a thinner separation membrane so that an electrochemical element having excellent power generation performance can be provided. However, the thin fiber aggregate is easily charged and may be inferior in handleability. In particular, when the average fiber diameter of the fiber aggregate is reduced, the surface area of the fiber is increased, so that the fiber is more easily charged and the handleability is inferior.
Then, as long as a separation membrane support having a fiber aggregate having poor handleability is used, it is difficult to provide a thin separation membrane, and as a result, it is difficult to provide an electrochemical element having excellent power generation performance. ..

An object of the present invention is to provide a separation membrane support for an electrochemical element having excellent handleability so that an electrochemical element having excellent power generation performance can be easily provided.

The first invention is "a separation membrane support for an electrochemical element including a fiber aggregate, wherein the fibers constituting the fiber aggregate contain a nonionic surfactant. Support. "
The second invention is "the separation membrane support for an electrochemical element according to claim 1, wherein the fiber contains a resin having a resin moisture content of 2.0% by mass or less as a constituent resin." be.

As a result of continuous studies by the inventors of the present application, it has been found that a fiber aggregate composed of fibers containing a nonionic surfactant is less likely to be charged and has excellent handleability. Therefore, the separation membrane support provided with the fiber aggregate is also difficult to be charged and has excellent handleability. Therefore, a thin separation membrane can be easily provided, and as a result, an electrochemical element having excellent power generation performance can be easily provided. Can be provided to.

Further, in an electrochemical element having a separation membrane reinforced with a separation membrane support between electrodes, the nonionic surfactant contained in the separation membrane support according to the present invention includes an electrolyte, an electrode, a conductive substance, a catalyst, and the like. It is considered that it is difficult to react with other constituent materials (hereinafter sometimes referred to as constituent materials) in electrochemical elements such as active materials.

When the separation membrane support contains a cationic surfactant or an anionic surfactant instead of the nonionic surfactant, and when these are eluted into the constituent material, the ion concentration of the constituent material May unintentionally change significantly and cause denaturation of the constituent material itself, as well as denaturing other constituent materials that are in contact with the constituent material, and the power generation performance and battery performance of the electrochemical element. May unintentionally decrease. On the other hand, when the separation membrane support contains a nonionic surfactant instead of a metal salt, a cationic surfactant or an anionic surfactant, or when the nonionic surfactant is eluted into the constituent material. Even if there is, it was found that the ion concentration of the constituent material is relatively hard to change. Therefore, it is possible to prevent the power generation performance and the battery performance of the electrochemical element from being unintentionally deteriorated.

From the above, according to the present invention, it is possible to prevent the power generation performance and the battery performance of the electrochemical element from being unintentionally deteriorated, and it is possible to easily provide the electrochemical element having excellent power generation performance and battery performance.

Further, as a result of examination, the applicant of the present application has made a resin having a resin moisture content of 2.0% by mass or less, such as a polysulfone resin, a polyethersulfone resin, a polyvinylidene fluoride resin, and an epoxy resin, into fibers constituting the fiber aggregate. It has been found that the separation membrane support provided with the fiber aggregate is more easily charged when the resin is contained. In the present invention, as described above, since the fibers constituting the fiber aggregate contain a nonionic surfactant, it is possible to provide a separation membrane support that is hard to be charged and has excellent handleability. Therefore, a fiber aggregate composed of fibers containing a resin having a resin moisture content of 2.0% by mass or less, which is more easily charged as a constituent resin (particularly, polysulfone resin, polyethersulfone resin, polyvinylidene fluoride resin, etc.) According to the present invention, the power generation performance of the electrochemical element can be improved even in the case of a separation film support provided with a separation film support (a fiber aggregate composed of fibers containing a resin having a resin moisture content of 0.43% by mass or less, which is more easily charged). It is possible to prevent an unintentional decrease and easily provide an electrochemical element having excellent power generation performance.

In the present invention, various configurations such as the following configurations can be appropriately selected. Unless otherwise specified, the various measurements described in the present invention were carried out under atmospheric pressure. Moreover, the measurement was carried out under the temperature condition of 25 ° C. Then, unless otherwise specified, the various measurement results described in the present invention were measured to a value one digit smaller than the desired value, and the value to be obtained was calculated by rounding off the value. As a specific example, when the value up to the first minority is the value to be obtained, the value up to the second minority is calculated by measurement, and the value up to the first minority is calculated by rounding off the obtained second minority value. Then, this value was used as the desired value.
Then, the numerical range that can be adopted can be determined by arbitrarily combining each upper limit value and each lower limit value described below as desired.

The separation membrane support of the present invention includes a fiber assembly. The fiber aggregate referred to in the present invention is, for example, a fiber web, a non-woven fabric, or a sheet-like cloth such as a woven fabric or a knitted fabric. The separation membrane reinforced by the separation membrane support provided with the fiber aggregate is flexible because it contains the fiber aggregate (particularly, a non-woven fabric), and is excellent in shape stability and dimensional stability.

Separation membranes with improved mechanical strength and separations that effectively suppress swelling and shrinkage that occur in liquids such as water and electrolytes because the average fiber diameter of the constituent fibers of the fiber assembly is as thin as 3 μm or less. A membrane can be provided, and as a result, a thinner separation membrane can be provided. The smaller the average fiber diameter, the easier it is for the above-mentioned effects to be exhibited. Therefore, the average fiber diameter of the constituent fibers is preferably 2 μm or less, more preferably 1 μm or less, further preferably 800 nm or less, and further preferably 600 nm. Most preferably: On the other hand, the lower limit of the average fiber diameter of the constituent fibers can be appropriately selected, but it is realistic that it is 20 nm or more so as to provide the separation film excellent in the above-mentioned function, and it is preferably 100 nm or more.
The "average fiber diameter" here is the arithmetic mean value of each fiber diameter of 50 fibers measured based on a 5000x electron micrograph of a cross section or surface of an object such as a fiber aggregate. say. When the fiber diameter is too small to measure, the measurement can be performed based on an electron micrograph having a magnification higher than 5000 times. When the cross-sectional shape of the fiber is non-circular, the diameter of a circle having the same area as the cross-sectional area is regarded as the fiber diameter.

The fiber length of the fiber is appropriately selected, but it can be a short fiber or a long fiber having a specific length, or a continuous fiber having a fiber length of a length that makes it difficult to substantially measure the fiber length. .. Since the number of fiber ends in the fiber assembly constituting the separation membrane support is small, the surface is smooth, the thickness is uniform, and various physical properties such as mechanical strength are excellent. As a result, a thinner separation membrane can be provided. , The fiber aggregate preferably contains fibers having a continuous length as constituent fibers, and more preferably, the constituent fibers of the fiber aggregate are only continuous fibers.
The "fiber length" referred to here can be measured based on a 5000x electron micrograph of a cross section or surface of an object such as a fiber aggregate or a separation film. When the fiber length of the fiber is too long and it is difficult to measure, the measurement can be performed based on an electron micrograph at a magnification lower than 5000 times.

The fiber preparation method can be appropriately selected. For example, the melt spinning method, the dry spinning method, the wet spinning method, and the direct spinning method (melt blow method, spunbond method, electrostatic spinning, which is a method of applying an electric field to the spinning liquid to spin the fibers. A method, a method of spinning using centrifugal force, a method of spinning using an accompanying air flow described in JP-A-2011-012372, and a type of electrostatic spinning method described in JP-A-2005-264374. Known methods such as a neutral spinning method) and a method of extracting fibers having a small fiber diameter by removing one or more kinds of resin components from the composite fiber can be used.

In particular, as disclosed in, for example, JP-A-2017-197876, JP-A-2016-199828, JP-A-2011-047089, etc., fibers spun by a direct spinning method (particularly, an electrostatic spinning method) are collected. By doing so, a non-woven fabric having an average fiber diameter of 3 μm or less can be prepared. Further, by collecting the fibers spun by the direct spinning method (particularly, the electrostatic spinning method), a fiber web or a non-woven fabric composed of only continuous fibers can be prepared.

A fiber web can be prepared by subjecting the fibers prepared by the above method to, for example, a dry method or a wet method, and the constituent fibers of the prepared fiber web can be entangled and / or integrated to prepare a non-woven fabric. As a method of entwining and / or integrating the constituent fibers with each other, for example, a method of entwining with a needle, a water stream, or a fluid flow such as steam / gas, or a fiber web being subjected to a heat treatment, which is composed of a binder or an adhesive fiber. Examples thereof include a method of adhering and integrating fibers with each other or melting and integrating them.

The heat treatment method can be appropriately selected, and for example, a method of heating and pressurizing with a calendar roll, a method of heating with a hot air dryer, a method of irradiating infrared rays under no pressure to heat the contained organic resin, and the like are used. Can be done. Alternatively, a direct spinning method may be used to spin and collect the fibers to prepare a fiber web or non-woven fabric. When the electrostatic spinning method is adopted, it is preferable to use a spinning liquid having a spinnability. By using a spinning liquid having a spinnability, it is possible to prepare a fiber web or a non-woven fabric made of fibers having a smaller average fiber diameter and a uniform fiber diameter, which is preferable. Whether or not the spinning solution has spinnability can be determined by the method described in JP-A-2017-053078.

In addition to the fiber web, the non-woven fabric may be used for the method of entwining and / or integrating the constituent fibers described above.

The fiber is, for example, a polyolefin resin (polyethylene, polypropylene, polymethylpentene, a polyolefin resin having a structure in which a part of hydrocarbon is replaced with a nitrile group or a halogen such as fluorine or chlorine), a styrene resin, or a polyether resin. (Polyethylene glycol, polypropylene glycol, polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), phenol-based resin, melamine-based resin, urea-based resin, epoxy-based resin, polyester-based resin (polyethylene terephthalate, poly) Trimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, polylactic acid, total aromatic polyester resin, unsaturated polyester resin, etc.), polyimide resin, polyamideimide resin, polyamide resin (For example, aromatic polyamide resin such as aramid resin, aromatic polyetheramide resin, nylon resin, etc.), urethane resin, epoxy resin, polysulfone resin (polysulfone, etc.), polyethersulfone resin (polyethersulfone, etc.) Sulfated polyether sulfone, etc.), fluororesins (polytetrafluoroethylene, polyvinylidene fluoride, perfluorosulfonic acid resins, etc.), polysaccharides (starch, cellulose-based resin purulan, alginic acid, hyaluronic acid, etc.), vinyl alcohol-based resins (Polyvinyl alcohol, polyvinyl acetate, etc.), polycaprolactone, polyglycolic acid, polyvinylpyrrolidone, polybenzoimidazole resin, acrylic resin (for example, polyacrylonitrile resin obtained by copolymerizing acrylic acid ester or methacrylate ester, acrylonitrile) It can be a fiber having a known resin such as vinyl chloride or a mod acrylic resin copolymerized with vinylidene chloride), and even if the fiber is composed of only one kind of resin, there are multiple kinds such as a mixed resin. It may be a fiber composed of a resin.

Separation that is excellent in handling because it is excellent in mechanical strength and elongation because the fibers constituting the fiber aggregate contain at least one of polysulfone-based resin, polyethersulfone-based resin, and polyvinylidene fluoride-based resin. Membrane supports can be provided. Further, as will be described in detail later, a separation membrane formed by combining a separation membrane support composed of these resins having a low water content is excellent in dimensional stability when water content is contained. In order to effectively exert such a function, the mass of these resins in the mass of the constituent resins of the fibers constituting the fiber aggregate is preferably 60% by mass or more, preferably 80% by mass or more. Is preferable, 95% or more is preferable, and 100% by mass is most preferable.

The polysulfone-based resin, polyethersulfone-based resin, polyvinylidene-fluoride resin, epoxy-based resin, polyamide-based resin, polyurethane-based resin, acrylonitrile-based resin, polyimide-based resin, polyamideimide-based resin, and polystyrene-based resin have a resin moisture content. For example, the resin moisture content of polyvinylidene fluoride used in Examples described later representing these resins is 0.03% by mass, and the resin moisture content of polyether sulfone is 0.43% by mass. The resin moisture content of the polysulfone is 0.23% by mass, and that of the epoxy resin is 2.0%.

The resin water content in the present invention refers to the percentage of the mass of water that can be contained in the resin in the mass of the resin. The applicant of the present application has found that when the fibers constituting the fiber aggregate contain a resin having a low resin water content, the separation membrane support provided with the fiber aggregate is more easily charged. Therefore, the separation membrane support provided with the fiber aggregate composed of the fibers containing these resins is more easily charged, but the fibers containing these resins contain a nonionic surfactant. Therefore, it is possible to provide a separation membrane support that is hard to be charged and has excellent handleability.

The resin moisture content of the constituent resin of the fiber referred to here is a measured value obtained by using the constituent resin as a sample and subjecting it to the Karl Fischer titration method described in JIS K0113: 2005 “General Rules for Karl Fischer Titration Method for Potential Difference / Current / Electricity”. Is. When the resin moisture content of the constituent resin used in a catalog or a paper is described, the resin moisture content can be used as the resin moisture content of the constituent resin.

These resins may be made of either a linear polymer or a branched polymer, and the resin may be a block copolymer or a random copolymer. Further, the three-dimensional structure of the resin and the presence or absence of crystallinity may be used.

Further, the fiber may be a single fiber, a fibril-like fiber, or a composite fiber. The composite fiber can be, for example, a core-sheath type, a sea-island type, a side-by-side type, an orange type, a bimetal type or the like.

The fiber may have a deformed cross-sectional fiber in addition to the substantially circular fiber and the elliptical fiber in the cross-sectional shape. In addition, as the irregular cross-sectional fiber, a polygonal shape such as a hollow shape or a triangular shape, an alphabet character shape such as a Y shape, an amorphous shape, a multi-leaf shape, a symbolic shape such as an asterisk shape, or a plurality of these shapes Examples of fibers having a fiber cross section such as a bonded shape can be exemplified.

The type and mixing ratio of the fibers can be appropriately selected, and a fiber aggregate composed of only one type of fiber or a fiber aggregate composed of a mixture of a plurality of types of fibers may be used.

The fibers that make up the fiber aggregate are integrated by entwining the constituent fibers, or are integrated by a binder, but some of the constituent fibers are melted and the intersections of the fibers are integrated. May be good. A non-woven fabric obtained by spinning and collecting fibers by using a direct spinning method is preferable because a fiber aggregate of the non-woven fabric can be formed without using an unnecessary component such as a binder.

The fiber aggregate may include a functional agent such as particles in addition to the constituent fibers. The type of particles can be appropriately selected, and for example, silica particles, titania particles, zirconia particles, yttria-stabilized zirconia particles, alumina particles, metal-organic framework (MOF), and various polymer particles can be used. Moreover, the surface of these particles may be modified. The particle shape can also be appropriately selected, and can be fibrous, flat, spherical, beaded, rod-shaped, or the like. Further, the particles may be solid particles or hollow particles, and may have a porous particle shape.

The functional agent is in a mode such that the functional agent is supported by melting a part of the constituent fibers of the fiber aggregate in the surface or the internal voids of the fiber aggregate, or is supported by a binder. Can be done. Alternatively, the functional agent may be embedded in the constituent fibers.

The fiber aggregate of the present invention is characterized in that its constituent fibers contain a nonionic surfactant. The nonionic surfactant referred to here is also referred to as a nonionic surfactant, and among the surfactants, a hydroxyl group or an ether bond portion that does not have a group that dissociates ions in water and does not dissociate in water. Is a general term for surfactants having a hydrophilic group.

Such nonionic surfactants include, for example, (1) saturated or unsaturated linear or branched higher alcohols having 8 to 22 carbon atoms, polyhydric alcohols, or aromatic alcohols, and alkylene oxides. (Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide.) Ether type such as alkyl ether, alkenyl ether, alkynyl ether, or aryl ether of polyoxyalkylene having added (2) 8 carbon atoms. Ester form of a higher alcohol having a linear or branched hydrocarbon group of ~ 22 saturated or unsaturated and a polyhydric fatty acid, (3) a higher fatty acid having 8 to 22 carbon atoms and a polyhydric alcohol Examples thereof include an ester compound or an alkanolamide type in which an alkylene oxide is added to the ester compound, which is an ester ether type (an alkanolamide type in which a tetrahydrophobic group and a hydrophilic group are amide-bonded).

Specifically, for example, as an ether type, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, and polyoxyethylene nonylphenyl. Polyoxyethylene alkyl phenyl ether such as ether; as an ester type, polyethylene glycol dilaurate, polyoxyethylene alkyl ester such as polyethylene glycol distearate ;; polyoxyethylene sorbitan fatty acid ester; glycerin fatty acid ester; sucrose fatty acid ester; ester. Examples of the ether type include fatty acid polyethylene glycol; fatty acid polyoxyethylene sorbitan; and alkanolamide types include polyoxyethylene alkylamide and fatty acid alkanolamide.

The mode in which the fiber contains a nonionic surfactant can be appropriately selected, and even in the mode in which the nonionic surfactant is attached to the fiber surface, the nonionic surfactant is mixed in the constituent resin of the fiber. It may be the mode in which it is used. However, in order to prevent the nonionic surfactant from being unintentionally eluted in a large amount into the constituent material of the electrochemical element and unintentionally deteriorating the power generation performance of the electrochemical element, the nonionic surfactant is contained in the constituent resin of the fiber. It is preferably contained by mixing a surfactant. The fibers (fiber aggregates) of such an embodiment can be produced by directly spinning using a spinning liquid obtained by mixing a resin and a nonionic surfactant.

The fiber may contain a nonionic surfactant, and may contain other types of surfactant. However, when these are eluted into the constituent material, the ion concentration of the constituent material may change significantly unintentionally, which may lead to denaturation of the constituent material itself, and of course, it exists in contact with the constituent material. There is a risk of denaturation of the constituent materials of the above, and there is a risk of unintentionally degrading the power generation performance of the electrochemical element. Therefore, it is preferable that the fiber contains only a nonionic surfactant as a surfactant.

The amount of the nonionic surfactant contained in the fiber is appropriately adjusted so as to achieve the object of the present invention, but if the amount is too small, it is difficult to be charged and a separation membrane support having excellent handleability is provided. Since it may be difficult to provide an electrochemical element having excellent power generation performance if the amount is too large, the mass ratio of the nonionic surfactant to the fiber mass is 0 mass. It is preferably more than% and 20% by mass or less, preferably 0.05 to 15% by mass, and more preferably 0.1 to 10% by mass.

Various physical properties such as the basis weight and thickness of the fiber aggregate can be appropriately selected. For example, the basis weight may be 0.1 to 200 g / ^{m 2,} can be a 0.3~100g / ^{m 2,} can be a 0.5~20g / ^{m 2,} 1~10g / It can be m ^2. The "Metsuke" of the present invention means a value measured as 10 cm × 10 cm according to JIS L1085. For example, the thickness can be 0.5 μm to 1.5 mm, can be 1 μm to 1 mm, can be 1 μm to 100 μm, can be 2 μm to 50 μm. The "thickness" referred to in the present invention is randomly selected by the measurement method of JIS C2111 5.1 (1) using an outer micrometer (0 to 25 mm) specified in JIS B7502: 1994. It means the average value of 10 points measured in.

The fiber aggregate according to the present invention can be used alone as a separation membrane support, but if necessary, a base material (for example, a sheet-like cloth, a film having ion permeation performance, ion permeation) separately prepared for the fiber aggregate can be used. A foamed sheet having performance, a plate having ion permeation performance, etc.) may be laminated to form a separation membrane support.

The method of laminating the fiber aggregate and the base material can be appropriately selected, but a method of simply laminating, a method of laminating and integrating the fiber aggregate and / or the constituent components of the base material by partially melt-bonding, or a method of laminating and integrating with a binder, A method of preparing a laminate by accumulating the spun fibers on the main surface of the base material and forming a fiber aggregate on the base material can be adopted.

The fiber aggregate or the laminate of the fiber aggregates produced as described above is subjected to a pressurizing process such as a reliant press process according to the intended use and usage mode, and the thickness is adjusted by a sulfonate treatment or a sulfonate treatment. It may be subjected to various secondary steps such as being subjected to hydrophilization treatment such as plasma treatment or fluorine gas treatment, punching of a shape, and molding.

By combining the membrane-constituting resin constituting the separation membrane and the separation membrane support, a separation membrane reinforced with the separation membrane support can be prepared. The type of film-constituting resin constituting the separation film is appropriately selected depending on the properties of the separation film to be obtained, or the constituent fibers of the fiber aggregate, and is, for example, a polyolefin resin (for example, polyethylene, polypropylene, etc.). Polymethylpentene, etc.), styrene resins (eg, polystyrene, acrylonitrile-butadiene-styrene copolymer, etc.), polyester resins (eg, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylenena) Phtalate, polycarbonate, polyarylate, total aromatic polyester resin, etc.), acrylic resin (eg, polyacrylonitrile, etc.), polyamide resin (eg, 6 nylon, 66 nylon, etc.), polyether resin (eg, polyethylene oxide, etc.) Polyetheretherketone, polyacetylene, polyphenylene ether, modified polyphenylene ether, aromatic polyetherketone, etc.), urethane-based resin, fluororesin (eg, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polyphenylene sulfide, polyamideimide resin, Thermoplastic resins such as polysulfone resins (eg, polysulfone, polyethersulfone, etc.); thermocurable resins such as phenolic resins, melamine resins, epoxy resins; polyimide resins, aromatic polyamide resins, aromatic polyetheramide resins, Examples thereof include synthetic polymer resins such as polybenzoimidazole resins, polybenzoxazoles, polybenzthioazoles, polyindoles, and aromatic organic resins such as polyquinoline.

As another example, fluororesins such as perfluorosulfonic acid; polyethylene oxide gel containing metal ions, sulfonated polyimide, sulfonated polyarylene ether, sulfonated polybenzimidazole, sulfonated polyphenylene, sulfonated polyphenylene oxide, polyphenylene. Sulfones, sulfonated polystyrenes and their copolymers, polyvinyl sulfonic acids and their copolymers, sulfonated polysulfone-based resins (eg, sulfonated polyether sulfones, sulfonated polyether ether sulfones, sulfonated polysulfones, etc.), sulfonated polysulfones. Examples thereof include hydrocarbon-based resins such as ether ether ketone; and ionic conductive resins such as. Further, a super absorbent polymer such as polyacrylic acid gel and polyhydroxyethyl methacrylate gel; a biopolymer gel such as agar and gelatin; and the like can be mentioned.

Other examples include polyvinyl alcohol, starch, pullulan, carboxymethyl cellulose, polyacrylic acid, polyacrylamide, polyalcohol (eg, ethylene glycol, glycerol, etc.), polyamine, polyvinylpyrrolidone, xanthan gum, sodium alginate, carrageenan, glucomannan, etc. be able to.

In particular, when preparing an electrolyte membrane for a fuel cell, it is known that it can be used as a constituent resin of the electrolyte membrane for a fuel cell (for example, disclosed in Japanese Patent Application Laid-Open No. 2004-119223). Fluorocarbon sulfonic acid-based resin, sulfonated aromatic hydrocarbon-based resin, alkyl sulfonated aromatic hydrocarbon-based resin, inorganic-organic composite resin disclosed in JP-A-2018-018684, JP-A-2017-195087, etc. It is preferable to adopt.

The separation membrane may include a functional agent such as particles as described above in addition to the separation membrane support and the membrane constituent resin.

The separation membrane described above can be used alone, but if necessary, a base material may be separately laminated on the separation membrane. The method of laminating the separation membrane and the base material can be appropriately selected, but a method of simply laminating, a method of laminating and integrating the separation membrane and / or the constituent components of the base material by partially melting and adhering, or a method of laminating and integrating with a binder is adopted. can.

The separation membrane or the laminate of the separation membranes produced as described above is subjected to a pressure treatment step such as a reliant press treatment to adjust the thickness according to the application and usage mode, and is subjected to a sulfonate treatment or a plasma treatment. Alternatively, it may be subjected to various secondary steps such as hydrophilization treatment such as fluorine gas treatment, punching of a shape, and molding.

Next, the method for producing the separation membrane support according to the present invention will be illustrated and described. The points having the same configuration as the items already described will be omitted.
The method for producing the separation membrane support according to the present invention can be appropriately selected, but as an example,
(1) A step of preparing a spinning solution prepared by dissolving a resin and a nonionic surfactant in a solvent or a spinning solution prepared by dispersing the resin and a nonionic surfactant in a dispersion medium.
(2) A step of preparing a fiber web by applying a spinning solution to an electrostatic spinning device and spinning it by reducing the diameter, and collecting the obtained fibers.
(3) Step of removing solvent or dispersion medium from fiber web,
A method for producing a fiber assembly comprising the above can be used.

First, the step (1) will be described.
The type of solvent or dispersion medium is appropriately selected, but N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, acetonitrile, dimethyl sulfoxide, 1,4-dioxane, pyridine, etc. Examples thereof include formic acid, toluene, benzene, cyclohexane, cyclohexanone, carbon tetrachloride, methylene chloride, chloroform, trichloroethane, ethylene carbonate, diethyl carbonate, propylene carbonate and the like. The solvent or dispersion medium may be one type or a mixed solvent or a mixed dispersion medium obtained by mixing a plurality of types.

The mixing ratio of the resin and the nonionic surfactant contained in the spinning solution is appropriately adjusted so that the desired fiber aggregate can be prepared, and the mass of the resin: the mass of the nonionic surfactant = 99.95% by mass: 0. 0.05% by mass to 80% by mass: preferably 20% by mass.

The spinning solution may contain a salt. By containing the salt, the conductivity of the spinning liquid is improved, shots are prevented from occurring when the spinning solution is subjected to an electrostatic spinning device, and a fiber web made of fibers having a uniform fiber diameter and a finer fiber diameter can be produced. The type of salt contained in the spinning solution can be appropriately selected, but a separation membrane composed of fiber aggregates composed of fibers substantially free of salt so that the salt does not easily remain in the fiber aggregates (more preferably). It is preferable to use a salt composed of an organic acid and a nitrogen compound that volatilizes in the step (3) described later (so that the support can be prepared). As such a salt, a salt composed of an organic acid and a nitrogen compound that volatilizes by heat treatment can be adopted, and examples thereof include ammonium acetate, ammonium formate, and ammonium oxalate. For example, ammonium acetate, ammonium formate, ammonium oxalate and the like are preferably used.

The mass (mass of solid content) of the salt contained in the spinning solution is appropriately selected so that the desired fiber aggregate can be prepared, but the mass of the salt contained in the spinning solution is 30% by mass or more with respect to the mass of the resin. If there is too much, the spinning solution may gel and it may not be possible to prepare fibers in the desired mode. Therefore, the mass of the salt contained in the spinning liquid is preferably 30 to 0.05% by mass, preferably 7.5 to 0.1% by mass, and 10 to 0.2% by mass with respect to the mass of the resin. It is preferably mass%.

Further, the spinning liquid may contain a functional agent. For example, it may contain a radical scavenger (quencher) added for the purpose of suppressing radical deterioration in order to prolong the life of the electrolyte membrane for a fuel cell. The mass (solid content mass) of the functional agent contained in the spinning solution is appropriately selected so that the desired fiber aggregate can be prepared, but can be 0.01 to 30% by mass and 0.05 to 20 mass. It can be%, and it can be 0.1 to 15% by mass.

The temperature and viscosity of the spinning solution are appropriately selected so that the desired fiber aggregate can be prepared. The temperature of the spinning solution can be 5-40 ° C, 10-35 ° C, and 15-30 ° C. Further, the viscosity of the spinning liquid can be 0.05 to 8 Pa · s, 0.1 to 6 Pa · s, and 0.2 to 5 Pa · s. In addition, this "viscosity" refers to the value at ^{a shear rate of 100s-1} o'clock measured at a temperature of 25 ° C. using a viscometer measuring device.

Next, step (2) will be described.
The method of spinning by reducing the diameter of the spinning liquid is appropriately selected so that the desired fiber aggregate can be prepared. For example, a direct spinning method (particularly, an electrostatic spinning method) can be adopted. When the electrostatic spinning method is adopted, a voltage is applied to the spinning liquid, and a voltage opposite to the voltage is applied to a counter electrode such as a metal plate provided at a distance from the discharge portion of the spinning liquid. To the counter electrode to reduce the diameter. Then, the fiber web is formed on the collector by collecting the spun liquid having a reduced diameter in the collector. The counter electrode such as the metal plate described above may be used as the collector.

Then, the step (3) will be described.
The method of removing the solvent or the dispersion medium from the fiber web can be appropriately selected, and as an example, a method of subjecting the fiber web to heat treatment can be adopted. The type of heating device can be appropriately selected. For example, a method using a device that heats or pressurizes with a roll, an oven dryer, a far-infrared heater, a dry heat dryer, a hot air dryer, a device that can irradiate and heat infrared rays, and the like. Can be adopted. The heating temperature by the heating device is appropriately selected, but it is appropriately adjusted so that the residual solvent or dispersion medium can be volatilized and removed, and the constituent components such as constituent fibers are not unintentionally decomposed or denatured. ..

When an adhesive component or a crosslinkable resin is present in the constituent fibers of the fiber web, the fiber may be bonded by the adhesive component by subjecting it to heat treatment, or the crosslinkable resin may be crosslinked.

Further, when a salt composed of an organic acid and a nitrogen compound that volatilizes by heat treatment is present in the constituent fibers of the fiber web, the salt may be volatilized and removed by subjecting it to heat treatment. By volatilizing and removing the salt by heat treatment, a separation membrane support composed of fiber aggregates composed of fibers substantially containing no salt can be prepared.

By the above manufacturing method, a fiber assembly satisfying the constitution according to the present invention can be manufactured. The prepared fiber aggregate may be used as it is as a separation membrane support, but it is subjected to a sulfonate treatment, a plasma treatment, or a fluorine gas treatment, which is provided to a pressurizing device such as a calendar to smooth the surface or adjust the void ratio. It may be used as a separation membrane support after being subjected to various processing steps such as being subjected to a hydrophilization treatment such as, or punching a shape according to a usage mode.

Further, another constituent member such as another porous body, a film, or a foam may be laminated on the fiber aggregate, and the laminated body may be used as a separation membrane support.

The method for preparing the separation membrane using the separation membrane support according to the present invention can be appropriately selected, but a method for applying a solution or dispersion of a resin (membrane constituent resin) constituting the separation membrane to the separation membrane support can be used. Can be adopted. The method of applying can be appropriately selected, and a well-known method such as a method using a doctor blade or a method using a gravure roll can be adopted. The amount of the membrane-constituting resin supported on the separation membrane support can be appropriately adjusted. Further, a well-known resin can be used as the film-constituting resin according to the application.

A method of removing the solvent or the dispersion medium from the separation membrane support to which the membrane constituent resin solution or the dispersion liquid is applied can be appropriately selected, and as an example, a method of being subjected to heat treatment can be adopted. The type of heating device can be appropriately selected from the above-mentioned heating devices.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Preparation method of spinning liquid)
Polyvinyl alcohol was dissolved in water (boiling point: 100 ° C.), and polyvinylidene fluoride was dissolved in dimethylformamide (boiling point: 153 ° C.) to prepare various spinning solutions having the compositions shown in Table 1. Items that are not included are marked with a "-" in the table. The resin moisture content of the polyvinyl alcohol used was 3.7% by mass, and the resin moisture content of polyvinylidene fluoride was 0.03% by mass.

(Electrostatic spinning equipment and electrostatic spinning conditions)
-Shape of the spinning liquid discharge part in the metal nozzle (spinning liquid discharge part): Circular shape with an inner diameter of 0.44 mm-Distance between the tip of the metal nozzle and the fiber collector (metal plate): 4 cm
-Voltage applied to the spinning solution: 8 kV
-Spinning liquid discharged from a metal nozzle: 1 g / hour

(Reference example)
The spinning liquid A0 was spun by reducing the diameter using an electrostatic spinning device based on the above-mentioned (electrostatic spinning device and electrostatic spinning conditions). Then, the obtained fibers were collected on the surface of a metal plate as a collector to prepare a fiber web.
Then, the prepared fiber web was brought into contact with a heating roll whose surface temperature was adjusted to 160 ° C. for 10 minutes to remove the solvent from the fiber web to prepare a non-woven fabric, and the prepared non-woven fabric was used as a separation membrane support.

(Comparative Example 1)
The spinning liquid A1 was spun by reducing the diameter using an electrostatic spinning device based on the above-mentioned (electrostatic spinning device and electrostatic spinning conditions). Then, the obtained fibers were collected on the surface of a metal plate as a collector to prepare a fiber web.
Then, the prepared fiber web was brought into contact with a heating roll whose surface temperature was adjusted to 160 ° C. for 10 minutes to remove the solvent from the fiber web to prepare a non-woven fabric, and the prepared non-woven fabric was used as a separation membrane support.

(Comparative Example 2)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution A2 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Example 1)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution B1 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Example 2)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution B2 was used, and the prepared non-woven fabric was used as a separation membrane support.

The physical characteristics of each of the prepared separation membrane supports were evaluated and summarized in Table 2. The "charge amount", "handleability" and "conductivity" were measured and evaluated by the following methods.

(Measurement method of charge amount)
By subjecting a sample collected from an object to be measured such as a separation membrane support to the B method (friction withstand voltage test) described in JIS L1094: 2014 “Method for testing chargeability of woven fabrics and knitted fabrics”, the amount of charge (unit: unit:: kV) was measured. Then, the measured value was taken as the charge amount (unit: kV) of the object to be measured. The higher the absolute value of the measured value, the more charged the object to be measured.

(Evaluation method of handleability)
The prepared separation membrane support was sandwiched between glassine papers, and the handleability when the support was held in the hand was evaluated based on the following judgment. The handleability was evaluated in an environment of 20 ° C. and 65% RH.
X: Since the separation membrane support is charged, it sticks to the hand and is inferior in handleability.
〇: It did not stick to the hand and was excellent in handleability.

(Measurement method of conductivity)
1. 1. From the object to be measured such as the separation membrane support, 0.5 g of the fiber constituting the object to be measured was collected and used as a sample.
2. The sample was immersed in 100 g of purified water kept at 60 ° C. for 30 minutes. The purified water used in this measurement refers to water having a conductivity of 0.1 μS / cm (25 ° C.) or less classified as A4 based on JIS K0557, and the purified water is an electrodialysis pure water production device (Advantech). , RFP843RA).
3. 3. Using a conductivity meter (manufactured by Kyoto Denshi Kogyo Co., Ltd., CM-117), the conductivity (unit: μS) of purified water after taking out the sample was measured.
The higher the conductivity, the greater the unintentional change in the ion concentration of purified water due to the eluate from the object to be measured (for example, a surfactant).

The separation membrane support prepared in the reference example was excellent in handleability because the amount of charge was small and it was difficult to charge. On the other hand, the separation membrane support prepared in Comparative Example 1 was inferior in handleability because it had a large amount of charge and was easily charged. It was considered that the reason for this was that the resin moisture content of the resin constituting the separation membrane support prepared in Comparative Example 1 was as low as 2.0% by mass or less.

From the results of comparing Comparative Example 1 with Example 1 and Comparative Example 2, the separation membrane support provided with the fiber aggregate composed of fibers containing a surfactant has a small amount of charge and is difficult to be charged, so that it is easy to handle. It was excellent.

Further, from the results of comparing Comparative Example 2 and Example 1, the separation membrane support provided with the fiber aggregate composed of fibers containing a nonionic surfactant is excellent in handleability because the amount of charge is small and it is difficult to be charged. At the same time, since the conductivity was low, it was possible to prevent an unintentional large change in the ion concentration of the electrolyte.

(Preparation method of spinning liquid)
Polyvinylidene fluoride was dissolved in dimethylformamide (boiling point: 153 ° C.), and polysulfone, polyethersulfone and epoxy resin were dissolved in dimethylacetamide (boiling point: 165 ° C.), and various spinning solutions having the compositions shown in Table 3 were prepared. Items that are not included are marked with a "-" in the table. The resin water content of the polyether sulfone used was 0.43% by mass, the resin water content of the polysulfone was 0.23% by mass, and the resin water content of the epoxy resin was 2.0% by mass. For ease of understanding, Table 3 also shows the compositions of the spinning solution A1 and the spinning solution B1. In addition, items that are not included are marked with a "-" in the table.

(Comparative Example 3)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution A3 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Example 3)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution B3 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Comparative Example 4)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution A4 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Example 4)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution B4 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Comparative Example 5)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution A5 was used, and the prepared non-woven fabric was used as a separation membrane support.

(Example 5)
A non-woven fabric was prepared in the same manner as in Comparative Example 1 except that the spinning solution B5 was used, and the prepared non-woven fabric was used as a separation membrane support.

The physical characteristics of each of the prepared separation membrane supports were evaluated and summarized in Table 4. For ease of understanding, Table 4 also shows the results of Comparative Example 1 and Example 1.

From the results of comparing the comparative examples and the examples summarized in Table 4, according to the present invention, a resin (polysulfone-based resin, polyethersulfone-based resin) having a resin moisture content of 2.0% by mass or less, which is more easily charged as a constituent resin, is used. Even if it contains resin, polyvinylidene fluoride resin, epoxy resin), it is easy to handle, and because of its low conductivity, it is possible to prevent the ion concentration of the electrolyte from changing significantly. It was something that could be provided.

(Example 6)
A dispersion having 20% by mass of Nafion in the dispersion medium was prepared. Then, after applying the dispersion to the exposed surface of the separation membrane support (thickness: 11 μm) prepared in Example 1 on the polyethylene terephthalate film by the casting method, the heating temperature of each polyethylene terephthalate film is set to 80. It was dried by subjecting it to an oven set at ° C. for 30 minutes. Further, after that, it was subjected to an annealing treatment by subjecting it to an oven in which the heating temperature was set to 130 ° C. for 10 minutes.
In this way, a separation membrane (thickness: 15 μm, ratio of the separation membrane support to the molecular membrane: 10% by mass) was prepared in which Nafion was reinforced by the separation membrane support. Further, when the prepared separation membrane was impregnated in pure water at 80 ° C. for 30 minutes, the dimensional change before and after immersion was 6%.

A separation membrane (thickness: 15 μm) composed only of Nafion was prepared in the same manner except that the separation membrane support was not used for compounding. When the separation membrane thus prepared was impregnated in pure water at 80 ° C. for 30 minutes, the dimensional change before and after immersion was 17%.
From this, it has been possible to provide a separation membrane having excellent dimensional stability during use of an electrochemical device according to the present invention.

From the above, according to the present invention, it is possible to prevent the power generation performance of the electrochemical device from being unintentionally lowered, and it is possible to easily provide the electrochemical device having excellent power generation performance.

INDUSTRIAL APPLICABILITY The present invention can be suitably used as a separation membrane support for a fuel cell or a polymer electrolyte membrane support for a solid-state battery. Further, since the separation membrane support according to the present invention has excellent wettability, a resin having high hydrophilicity to the separation membrane support (for example, polyethylene oxide or polyvinylidene fluoride capable of forming a separation membrane for a solid battery). By applying the above, a separation film can be prepared with good film-forming properties.

The separation membrane support according to the present invention is used for various industrial applications (for example, a liquid separation membrane such as a water treatment membrane, a gas separation membrane, and a liquid such as water) in addition to the use for reinforcing the separation membrane of an electrochemical element. As a support for separation membranes that can be used for various industrial applications such as separation membranes, medical materials, ion exchange membranes and dialysis membranes, polymer electrolyte membranes for fuel cells, etc. It can be used for separators for electrochemical elements such as primary / secondary batteries, prepregs, gas filters, liquid filters, etc.).

Claims (2)

A separation membrane support for an electrochemical element including a fiber aggregate, wherein the fibers constituting the fiber aggregate contain a nonionic surfactant. The separation membrane support for an electrochemical element according to claim 1, wherein the fiber contains a resin having a resin moisture content of 2.0% by mass or less as a constituent resin.