JP2019179678A - Diaphragm for electrochemical element and use thereof - Google Patents

Abstract

To provide a diaphragm for an electrochemical element, excellent in adhesion between an organic layer and a support and capable of exhibiting excellent gas barrier properties.SOLUTION: A diaphragm for an electrochemical element includes a support and an organic layer containing a binder polymer. The organic layer further contains inorganic compound particles, and the support is a hydrocarbon-based porous body having a hydrophilic functional group. The hydrocarbon-based porous body having a hydrophilic functional group has a concentration of an oxygen element with respect to 100 atm% of a carbon element of 10 atm% or more, in element concentration measured by X-ray photoelectron spectroscopy (ESCA).SELECTED DRAWING: None

Description

The present invention relates to a diaphragm for an electrochemical device. More specifically, the present invention relates to a diaphragm for an electrochemical device having excellent adhesion between an organic layer and a support and excellent gas barrier properties.

As for the laminated film composed of the organic layer and the support, various applications for various uses have been studied, and development of a laminated film having excellent characteristics required for each use has been made so far. As one of the uses of such a laminated film, a diaphragm for an electrochemical element such as a diaphragm for alkaline water electrolysis and a battery separator is known.

For example, a diaphragm for alkaline water electrolysis is a film used for electrolysis of water, which is one of the industrial production methods of hydrogen, and is used for separating an anode chamber and a cathode chamber in an electrolytic cell.
Water electrolysis is performed by the movement of electrons (or ions). Therefore, in order to perform electrolysis efficiently, the diaphragm for alkaline water electrolysis needs high ion permeability. In addition, a gas barrier property that can block oxygen generated in the anode chamber and hydrogen generated in the cathode chamber is required. Furthermore, since the electrolysis of water is performed at 80 to 90 ° C. using alkaline water having a high concentration of about 30%, high temperature resistance and alkali resistance are also required.

The battery separator is a film used for the purpose of insulating the positive electrode and the negative electrode in a battery such as a zinc secondary battery. The battery separator separates the positive electrode and the negative electrode, holds the electrolyte, and is an ion between the positive electrode and the negative electrode. Used to ensure conductivity. In a battery separator, dendrite grows as the battery is charged and discharged, which may cause a short circuit. Therefore, the battery separator is required to be able to suppress the generation of dendrite as much as possible in addition to the ionic conductivity.

Various diaphragms for electrochemical devices have been known so far.
For example, Patent Literature 1 includes an ion permeable membrane and a porous reinforcing body disposed on one side or both sides of the ion permeable membrane, and the ion permeable membrane includes a neutral acid ion exchange group and a weak acid ion exchange group. , Composed of a polymer having a strong basic ion exchange group, a medium basic ion exchange group or a weak basic ion exchange group, and the porous reinforcing body has wettability with respect to an aqueous potassium hydroxide solution having a concentration of 30% by weight. A diaphragm for alkaline water electrolysis is described.
Further, for example, Patent Document 2 discloses an alkaline water electrolysis diaphragm base material composed of thermoplastic fibers having a specific range of average single fiber fineness and the number of crimps, and alkaline water electrolysis in which the base material includes a nonwoven fabric. A diaphragm substrate is described.

JP 2013-249509 A Japanese Patent Laid-Open No. 2006-89197

However, the conventional diaphragm for an electrochemical device having an organic layer and a support has a problem that the adhesion between the organic layer and the support is insufficient and the gas barrier property is poor. In addition, due to recent advances in energy technology, the performance required for diaphragms for electrochemical devices has increased, and there is room for improvement.

This invention is made | formed in view of the said present condition, and it aims at providing the diaphragm for electrochemical elements which is excellent in the adhesiveness of an organic layer and a support body, and can exhibit the outstanding gas barrier property.

The inventor has conducted various studies on a diaphragm for an electrochemical device having an organic layer containing a binder polymer and a support. The organic layer further contains inorganic compound particles in addition to the binder polymer. It has been found that the use of a hydrocarbon-based porous body having a group and a specific range amount of oxygen element concentration results in excellent adhesion between the organic layer and the support, and the gas barrier properties are greatly improved. The invention has been completed.

That is, the present invention is an electrochemical device diaphragm comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support has a hydrophilic functional group. The hydrocarbon porous body, which is a hydrocarbon porous body and has the above hydrophilic functional group, has an oxygen element concentration of 10 atm with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). It is a diaphragm for electrochemical elements characterized by being at least%.

The hydrocarbon-based porous body having a hydrophilic functional group further has an elemental concentration measured by X-ray photoelectron spectroscopy (ESCA) having a sulfur element concentration of 0.5 atm% or more with respect to 100 atm% of carbon element. Is preferred.

The hydrocarbon-based porous body having a hydrophilic functional group further has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). Is preferred.

The diaphragm for an electrochemical element of the present invention has extremely excellent adhesion between the organic layer constituting the diaphragm and the support. Therefore, the diaphragm for electrochemical devices of the present invention has excellent gas barrier properties. The diaphragm for electrochemical devices of the present invention is particularly suitably used as a diaphragm for alkaline water electrolysis or a battery separator.

The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

1. Electrochemical element diaphragm The electrochemical element diaphragm of the present invention is an electrochemical element diaphragm comprising an organic layer containing a binder polymer and a support, wherein the organic layer further comprises inorganic compound particles, The support is a hydrocarbon-based porous body having a hydrophilic functional group, and the hydrocarbon-based porous body having the hydrophilic functional group is measured at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). The oxygen element concentration with respect to 100 atm% of carbon element is 10 atm% or more.
Since the diaphragm for electrochemical devices of the present invention has the above-described configuration, it has excellent adhesion between the organic layer constituting the diaphragm and the support, and excellent gas barrier properties.

In the diaphragm for an electrochemical device of the present invention, hydrogen bonds are formed between the binder polymer and inorganic compound particles and the hydrophilic functional group of the support at the interface between the organic layer and the support, and on the support surface. When the hydrophilic functional group is contained, the impregnation property of the forming material is improved when the support is coated and impregnated with the organic layer forming material, and the support and the organic layer are easily combined. The adhesion between the substrate and the support and the inside of the support are excellent.
As a result, it becomes difficult for gas to pass through a diaphragm and it is estimated that the outstanding gas barrier property is exhibited.

The diaphragm for electrochemical devices of the present invention includes an organic layer and a support. Each configuration will be described below.
<Organic layer>
The organic layer contains a binder polymer and further contains inorganic compound particles. When the organic layer further contains inorganic compound particles in addition to the binder polymer, the adhesiveness to the support described later can be excellent. Thus, the organic layer is preferably an inorganic / organic composite layer containing a binder polymer and inorganic compound particles.

(Inorganic compound particles)
Examples of the inorganic compound particles include particles made of a compound having at least one element selected from Group 1 to Group 17 of the periodic table. As the at least one element selected from Group 1 to Group 17 of the periodic table, at least one element selected from Group 1 to Group 15 of the periodic table is preferable, Group 2, Group 4 and At least one element selected from Group 6 is more preferable, and among these, at least one element selected from Mg, Ca, Sr, Ba, Ti, Zr, Hf, Cr, Mo, and W is more preferable, and Mg, Ti Particularly preferred is at least one element selected from Zr and Mo.

Moreover, as said inorganic compound particle | grain, the compound containing an oxide, a hydroxide, or a hydroxide layer is preferable, and the compound containing the oxide, hydroxide, or hydroxide layer containing said preferable element is preferable.
Among these, the inorganic compound particles include hydroxides containing Mg, Ca, Sr or Ba or compounds containing hydroxide layers, Mg, Ca, and the like, in that the adhesion between the organic layer and the support is further improved. An oxide containing at least one element selected from Sr, Ba, Ti, Zr, Hf, Cr, Mo and W is preferred, and a hydroxide or a compound containing a hydroxide layer containing Mg, Mg, Ti, Zr And an oxide containing at least one element selected from Mo.

As a compound containing the hydroxide or hydroxide layer containing Mg, magnesium hydroxide and hydrotalcite are preferable, and magnesium hydroxide is more preferable.
As the oxide containing at least one element selected from Mg, Ti, Zr, and Mo, magnesium oxide, titanium oxide, zirconium oxide, molybdenum oxide, and a solid solution in which different elements are dissolved in these oxides are preferable.
By using the preferred inorganic compound particles described above, the adhesion between the organic layer and the support can be further enhanced, and excellent gas barrier properties can be exhibited.

One kind of the inorganic compound particles may be used, or two or more kinds may be used in combination.

Examples of the shape of the inorganic compound particles include an indeterminate shape, a fine powder shape, a powder shape, a granular shape, a granular shape, a flake shape, a polyhedral shape, a rod shape, and a curved surface-containing shape. Among these, a fine powder form and a flake form are preferable in that the adhesion between the organic layer and the support can be further enhanced and excellent gas barrier properties can be exhibited.

The inorganic compound particles preferably have an average particle diameter of 0.001 μm or more, more preferably 0.05 μm or more, and still more preferably 0.1 μm or more. Moreover, it is preferable that it is 10 micrometers or less, it is more preferable that it is 2.0 micrometers or less, and it is still more preferable that it is 1.5 micrometers or less.
The said average particle diameter is a volume average particle diameter (D50) calculated | required from the particle size distribution measurement by a laser diffraction method. Specifically, the average particle diameter is obtained by dispersing the above-mentioned inorganic compound particles in ethanol and subjecting them to ultrasonic treatment using a laser diffraction / scattering type particle size distribution measuring apparatus (“Model number LA-920” manufactured by Horiba, Ltd.). And can be obtained by adjusting to the transmittance specified by the apparatus and measuring.

The content of the inorganic compound particles is preferably 30% by mass or more, more preferably 32% by mass or more, and further preferably 35% by mass or more with respect to 100% by mass of the diaphragm for electrochemical devices. preferable. In addition, the content of the inorganic compound particles is preferably 99% by mass or less, more preferably 45% by mass or less, and 43% by mass or less with respect to 100% by mass of the diaphragm for an electrochemical element. Is more preferable.

Further, the binder polymer is preferably contained in an amount of 1 part by mass or more, more preferably 22 parts by mass or more, further preferably 25 parts by mass or more, and more preferably 67 parts by mass or less, relative to 100 parts by mass of the inorganic compound particles. Preferably, it is more preferably 42 parts by mass or less, and still more preferably 40 parts by mass or less.

(Binder polymer)
Examples of the binder polymer include an aliphatic hydrocarbon group-containing polymer such as polyethylene; an aromatic hydrocarbon group-containing polymer such as polystyrene; an ether group-containing polymer such as alkylene glycol; a hydroxyl group-containing polymer such as polyvinyl alcohol; Amide group-containing polymers; Imide group-containing polymers such as polymaleimide; (Meth) acrylic polymers; Halogen-containing polymers such as polyvinylidene fluoride and polytetrafluoroethylene; Ammonium salt-containing polymers; Phosphonium salt-containing polymers; Polymers; natural rubber; conjugated diene polymers; sugars such as hydroxyalkyl cellulose (for example, hydroxyethyl cellulose); polymers such as amino group-containing polymers such as polyethyleneimine These binder polymers may be used individually by 1 type, and may be used in combination of 2 or more type.

Among them, an aliphatic hydrocarbon group-containing polymer, an aromatic hydrocarbon group-containing polymer, and a halogen atom-containing polymer in that the adhesion between the organic layer and the support can be further enhanced and excellent gas barrier properties can be exhibited. It is preferably at least one selected from the group consisting of a conjugated diene polymer and a (meth) acrylic polymer, an aromatic hydrocarbon group-containing polymer, a conjugated diene polymer, a halogen atom-containing polymer, and More preferably, it is at least one selected from the group consisting of (meth) acrylic polymers.

Examples of the aliphatic hydrocarbon group-containing polymer include polymers having monomer units derived from an aliphatic hydrocarbon group-containing monomer.
The aliphatic hydrocarbon group-containing monomer may be a monomer containing a chain or branched saturated hydrocarbon group or an unsaturated hydrocarbon group, or a monomer containing an alicyclic hydrocarbon group. Good.
Preferred examples of the aliphatic hydrocarbon group-containing monomer include olefins such as ethylene, propylene, butene, 1-hexene, 1-heptene, and 1-octene.
The aliphatic hydrocarbon group-containing polymer may be a homopolymer composed of one of the above aliphatic hydrocarbon group-containing monomers, or may be a copolymer composed of two or more.
As the aliphatic hydrocarbon group-containing polymer, polyolefins such as polyethylene, polypropylene, polybutene and polymethylpentene are preferable, and polyethylene and polypropylene are more preferable.

Examples of the aromatic hydrocarbon group-containing polymer include those having a monomer unit having an aromatic hydrocarbon group such as benzene, specifically, for example, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polystyrene. , Polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylsulfone, polyarylate, polyetherimide, polyimide, polyamideimide and the like. Among these, at least one selected from the group consisting of polysulfone, polyethersulfone, and polyphenylsulfone is preferable, and polysulfone is more preferable in that the gas barrier property of the diaphragm for electrochemical devices can be further enhanced.

Examples of the halogen atom-containing polymer include those having a monomer unit derived from a monomer containing a halogen atom such as a chlorine atom and a fluorine atom, such as an ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride. , Vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene, tetrafluoroethylene- And fluorine-containing polymers such as hexafluoropropylene-vinylidene fluoride copolymer.

The conjugated diene-based polymer is not particularly limited as long as it has a monomer unit derived from a conjugated diene monomer, but preferably has a monomer unit derived from an aromatic vinyl monomer.

The conjugated diene monomer is preferably an aliphatic conjugated diene monomer. Examples of the aliphatic conjugated diene monomer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, chloroprene, and the like, among which 1,3-butadiene is preferable. Conjugated diene monomers may be used alone or in combination of two or more.

The conjugated diene-based polymer may be a homopolymer such as polybutadiene or polyisoprene, or may be a copolymer. However, the gas barrier property of the diaphragm for an electrochemical device can be further enhanced. The copolymer is preferably a copolymer, and more preferably a copolymer further having a monomer unit derived from an aromatic vinyl monomer.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, and o-methoxy. Styrene, m-methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, p-ethoxystyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chloro Styrene, p-chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, o-tert-butoxystyrene, m-tert-butoxystyrene , P-tert-butoki Styrene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene and vinyltoluene. Among these, styrene and α-methylstyrene are preferable in that the heat resistance and mechanical strength of the diaphragm for electrochemical devices can be increased. These aromatic vinyl monomers may be used alone or in combination of two or more.

In the conjugated diene polymer, the mass ratio of the monomer unit derived from the aliphatic conjugated diene monomer and the monomer unit derived from the aromatic vinyl monomer is preferably 1/9 or more, and preferably 2/8 or more. Is more preferably 3/7 or more. The mass ratio is preferably 9/1 or less, more preferably 8/2 or less, and even more preferably 7/3 or less.

The conjugated diene polymer is preferably a styrene-butadiene copolymer or an acrylonitrile-butadiene copolymer in that the performance of the diaphragm for an electrochemical device can be further improved, and a styrene-butadiene copolymer. Coalescence is more preferred. These copolymers may be modified copolymers such as carboxy modification.

The conjugated diene polymer may have a monomer unit derived from an unsaturated monomer other than a monomer unit derived from an aliphatic conjugated diene monomer or a monomer unit derived from an aromatic vinyl monomer.

Examples of other unsaturated monomers include itaconic acid, acrylic acid, methacrylic acid, fumaric acid, maleic acid, acrylamidomethylpropanesulfonic acid, styrenesulfonate, and other acid group-containing vinyl monomers; methyl (meth) acrylate, (Meth) ethyl acrylate, (meth) propyl acrylate, (meth) acrylate n-butyl, (meth) acrylate isobutyl, (meth) acrylate t-butyl, (meth) acrylate pentyl, (meth) acryl (Meth) acrylic acid ester monomers such as hexyl acid, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 4-hydro (meth) acrylic acid Hydroxyl group-containing vinyl monomers such as sibutyl, nitrile group-containing vinyl monomers such as (meth) acrylonitrile, (meth) acrylamide, N-methylol (meth) acrylamide, N-ethylol (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) ) Bifunctional vinyl monomers such as (meth) acrylamide monomers such as acrylamide, divinylbenzene, ethylene glycol dimethacrylate, isopropylene glycol diacrylate, tetramethylene glycol dimethacrylate; 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxy Examples include vinyl monomers containing an alkoxysilane group such as propyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane. These may be used alone or in combination of two or more.

In 100% by mass of the conjugated diene polymer, the mass ratio of other unsaturated monomer-derived monomer units is preferably 40% by mass or less, more preferably 20% by mass or less, and 10% by mass or less. More preferably, it is more preferably 5% by mass or less.

The (meth) acrylic polymer in the present specification refers to a polymer having a structural unit derived from a (meth) acrylic monomer without having a monomer unit derived from a conjugated diene monomer. The (meth) acrylic monomer refers to a monomer having a acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups is replaced with another atom or atomic group, or a derivative of such a monomer.

The (meth) acrylic polymer is preferably a (meth) acrylic acid polymer. The (meth) acrylic acid polymer refers to a polymer having a structural unit derived from a (meth) acrylic acid monomer, and the (meth) acrylic acid monomer refers to an acryloyl group or a methacryloyl group, or hydrogen in these groups. An atom has a group replaced with another atom or atomic group, and a carboxylic acid group (—COOH group), a carboxylic acid group (—COOM group), or an acid anhydride group (—C (═O)) -O-C (= O) -group). M represents a metal salt, an ammonium salt, or an organic amine salt. Examples of the metal atom forming the metal salt include monovalent metal atoms such as alkali metal atoms such as lithium, sodium and potassium; divalent metal atoms such as calcium and magnesium; trivalent metals such as aluminum and iron. Atoms are preferred. As the organic amine forming the organic amine salt, alkanolamines such as ethanolamine, diethanolamine, and triethanolamine, and triethylamine are preferable. The (meth) acrylic acid monomer is preferably (meth) acrylic acid (salt). (Meth) acrylic acid (salt) is a monomer having an acryloyl group or a methacryloyl group and having a carboxylic acid group (—COOH group) or a carboxylic acid group (—COOM group).

For example, it is preferable that the monomer component for obtaining a (meth) acrylic acid-type polymer comprises a (meth) acrylic acid-type monomer and other copolymerizable unsaturated monomers.

In 100% by mass of the (meth) acrylic acid polymer, the content of the monomer unit derived from the (meth) acrylic acid monomer is 0.1 to 5% by mass, the monomer unit derived from another copolymerizable unsaturated monomer. The content is preferably 95 to 99.9% by mass. The content of the monomer unit derived from the (meth) acrylic acid monomer is 0.3% by mass or more, and the content of the monomer unit derived from another copolymerizable unsaturated monomer is 99.7% by mass or less. More preferably, the content of monomer units derived from (meth) acrylic acid monomers is 0.5% by mass or more, and the content of monomer units derived from other copolymerizable unsaturated monomers is 99.5% by mass or less. More preferably. By setting it within such a range, the monomer component is stably copolymerized.

Other copolymerizable unsaturated monomers include (meth) acrylic monomers other than (meth) acrylic acid monomers, unsaturated monomers having aromatic rings, acrylonitrile, trimethylolpropane diallyl ether and other polyfunctional unsaturated monomers And monomers.
Examples of the (meth) acrylic monomer other than the (meth) acrylic acid monomer include an acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups is replaced with another atom or atomic group. And a monomer having a carboxylic ester group or a derivative of such a monomer.

Examples of the (meth) acrylic monomer having a carboxylate group include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate , Isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl methacrylate Acrylate, isooctyl methacrylate, nonyl acrylate, nonyl methacrylate, isononyl acrylate, isononyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl Acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, diallyl phthalate, triallyl cyanurate, ethylene glycol dia Kure Ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate , Allyl acrylate, allyl methacrylate, etc .; esterified products of (meth) acrylic acid monomers other than these, and the like, and it is preferable to use one or more of these.

In 100% by mass of the (meth) acrylic acid polymer, the content of monomer units derived from (meth) acrylic monomers other than the (meth) acrylic acid monomer is preferably 20% by mass or more, and 40% by mass. % Or more is more preferable, and 60% by mass or more is more preferable. In addition, the content of monomer units derived from (meth) acrylic monomers other than the (meth) acrylic acid monomers is preferably 99.9% by mass or less, and more preferably 99.5% by mass or less. preferable.

Examples of the unsaturated monomer having an aromatic ring include divinylbenzene, styrene, α-methylstyrene, vinyltoluene, ethylvinylbenzene, and the like, and preferably styrene.

In 100% by mass of the (meth) acrylic acid polymer, the content of the monomer unit derived from the unsaturated monomer having an aromatic ring is preferably 1% by mass or more, and more preferably 5% by mass or more. More preferably, it is 10 mass% or more, More preferably, it is 20 mass% or more, It is especially preferable that it is 40 mass% or more. Further, the content of the monomer unit is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less. In addition, it is not necessary to use the unsaturated monomer which has an aromatic ring as a monomer component used as the raw material of the said (meth) acrylic-acid type polymer.

The binder polymer preferably has a weight average molecular weight of 10,000 or more and 6.5 million or less. The weight average molecular weight is more preferably 20,000 or more. The said weight average molecular weight can be measured as a weight average molecular weight converted into polystyrene by gel permeation chromatography (GPC) under the following conditions.
Device: HCL-8220GPC manufactured by Tosoh Corporation
Column: TSKgel Super AWM-H
Eluent (LiBr · H 2 O, NMP with phosphoric acid): 0.01 mol / L

The said binder polymer can be manufactured by polymerizing the monomer component which forms the structural unit which the polymer mentioned above contains, for example. The polymerization may be appropriately selected from known methods.

The content of the binder polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 7% by mass or more with respect to 100% by mass of the diaphragm for electrochemical devices. . Further, the content of the binder polymer is preferably 70% by mass or less, more preferably 35% by mass or less, and preferably 30% by mass or less with respect to 100% by mass of the diaphragm for an electrochemical element. Further preferred.

(Other ingredients)
The organic layer may contain other components in addition to the inorganic compound particles and the binder polymer described above. Examples of other components include carbon.

The organic layer can be formed using an organic layer forming material prepared by mixing the inorganic compound particles, the binder polymer, and other components as necessary with a solvent. The formation of the organic layer will be described in detail in the method for producing a diaphragm for an electrochemical element described later.

The thickness of the organic layer is preferably 10 to 1000 μm, more preferably 100 to 500 μm, and still more preferably 200 to 400 μm.

<Support>
In the present invention, the support is a hydrocarbon-based porous body having a hydrophilic functional group.
The hydrophilic functional group is not particularly limited, and is a hydroxyl group, carboxyl group, sulfonic acid group, sulfide group, disulfide group, fluoro group, carbonyl fluoride group, phosphoric acid group, amino group, imino group, amide group, alkylene. An oxide group, a phenol group, etc. are mentioned. Among these, the hydrophilic functional group includes a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a sulfide group, a fluoro group, and a carbonyl fluoride in that a hydrogen bond is formed with the inorganic compound particles and the binder polymer in the organic layer. Group and phosphoric acid group are preferable, and a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a sulfide group, a fluoro group, and a carbonyl fluoride group are more preferable.

The hydrocarbon-based porous body is a porous body made of a hydrocarbon-based polymer. Examples of the hydrocarbon polymer include aliphatic hydrocarbon polymers and aromatic hydrocarbon polymers. Moreover, these polymers have the said hydrophilic functional group, and the said hydrophilic functional group may be contained in either the principal chain or the side chain in the said hydrocarbon type polymer frame | skeleton.
Examples of the aliphatic hydrocarbon-based polymer include those similar to the aliphatic hydrocarbon group-containing polymer used in the organic layer described above.
Examples of the aromatic hydrocarbon polymer include those similar to the aromatic hydrocarbon group-containing polymer used in the organic layer described above.
Among these, the hydrocarbon polymer is preferably at least one selected from the group consisting of polyolefin, polyphenylene sulfide, and polyvinyl alcohol, in terms of achieving both alkali resistance and heat resistance, and polypropylene, polyethylene, and polyphenylene sulfide. More preferred is at least one selected from the group consisting of

The hydrocarbon-based porous body having the hydrophilic functional group may be composed of the hydrocarbon-based polymer having the hydrophilic functional group, or may have a hydrophilic functional group or not. It is also possible to introduce a hydrophilic functional group into the porous system.
As the method for introducing the hydrophilic functional group, the hydrocarbon porous body is subjected to a graft polymerization method such as a radiation graft polymerization method; a surface treatment method such as a plasma treatment, a corona treatment, a UV treatment, a UV ozone treatment; Treatment method; Sulfurous acid gas treatment method; Oxidation treatment with potassium dichromate solution or potassium permanganate solution, etc .; Etching treatment with sodium treatment solution etc .; Treatment with hydrophilic polymer or surfactant or fiber oil agent coating, etc. A well-known method is mentioned. Of these, the sulfurous acid gas treatment method and the fluorine gas treatment method are preferable.

The hydrocarbon-based porous body having a hydrophilic functional group has an oxygen element concentration of 10 atm% or more with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA).
When a hydrophilic functional group is introduced into the carbon-hydrogen porous material, the oxygen element concentration increases. In the present invention, when the oxygen element concentration of the support is in the above-described range, a hydrophilic functional group is introduced in a desired amount, and excellent adhesion between the above-described organic layer and the support is exhibited. It can be set as the diaphragm for electrochemical elements which has property.
The oxygen element concentration is more preferably 10 to 31 atm%.

In the present invention, it is preferable that when the hydrophilic functional group is introduced into the carbon-hydrogen porous body, at least the sulfur element concentration or the fluorine element concentration is increased in addition to the oxygen element concentration.
The hydrocarbon-based porous body having a hydrophilic functional group described above is capable of exhibiting even more excellent adhesion and gas barrier properties. Further, in the element concentration measured by X-ray photoelectron spectroscopy (ESCA), carbon The concentration of sulfur element with respect to 100 atm% of the element is preferably 0.5 atm% or more, and more preferably 0.5 to 20 atm%.
The hydrocarbon porous body having a hydrophilic functional group further has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). It is preferable that it is 3.5 to 12.5 atm%.

In the above-mentioned hydrocarbon-based porous body, the elemental concentration measured by X-ray photoelectron spectroscopy (ESCA) has an oxygen element concentration of 10 atm% or more with respect to 100 atm% of carbon element and a sulfur element concentration of 0.5 atm%. The embodiment described above is one of the more preferred embodiments in the present invention.
In the hydrocarbon-based porous body, the elemental concentration measured by X-ray photoelectron spectroscopy (ESCA) has an oxygen element concentration of 10 atm% or more with respect to 100 atm% of carbon element and a fluorine element concentration of 3. The aspect which is 5 atm% or more is also one of the more preferable aspects in this invention.
Further, in the hydrocarbon-based porous body, in the element concentration measured by X-ray photoelectron spectroscopy (ESCA), the oxygen element concentration with respect to 100 atm% of carbon element is 10 atm% or more, and the sulfur element concentration is 0.5 atm%. The aspect in which the fluorine element concentration is 3.5 atm% or more is one of the more preferable aspects in the present invention.

The oxygen element concentration, fluorine element concentration, and sulfur element concentration can be measured by X-ray photoelectron spectroscopy (ESCA). For example, an X-ray photoelectron spectrometer (JPS-9000MX, manufactured by JEOL Ltd., X-ray source) : MgKα ray).

The support is porous and preferably has a sheet shape.
The form of the support may be appropriately selected according to the purpose and use of the diaphragm for an electrochemical element of the present invention. For example, the nonwoven fabric, woven fabric, mesh, sintered porous membrane, or nonwoven fabric and woven fabric A mixed cloth etc. are mentioned, Preferably a nonwoven fabric, a woven fabric, or a mesh is mentioned.

The support preferably has a porosity of 10 to 90%. When the porosity is in the above range, a diaphragm for an electrochemical device having excellent ion conductivity and gas barrier properties can be obtained. The porosity is more preferably 20 to 85%, further preferably 25 to 80%.
The said porosity can be calculated | required by making a support body immersed in 20 degreeC ion-exchange water all day and night, and measuring the mass of the support body before and behind immersion. Specifically, it can be obtained by the following equation.
Porosity (volume%) = (mass of support after immersion−mass of support before immersion) / density of ion-exchanged water at 20 ° C./volume of support × 100

Although the thickness of the said support body can be suitably selected according to the objective and use of the diaphragm for electrochemical devices of this invention, for example, 10-300 micrometers is preferable, 50-250 micrometers is more preferable, 100-200 micrometers is further. preferable.

The configuration of the diaphragm for an electrochemical element of the present invention is not particularly limited as long as it has the above-described organic layer and support, and may be appropriately designed depending on the purpose and application. One side or both sides of the organic layer The structure which has the said support body may be sufficient, and the structure which has the said organic layer on both surfaces of the said support body may be sufficient.
The diaphragm for an electrochemical device of the present invention is preferably one in which at least a part of the support and the organic layer are integrated. By integrating, the adhesiveness between the support and the organic layer is excellent, and the gas barrier property of the diaphragm is further improved.

The total thickness of the diaphragm for an electrochemical element of the present invention may be appropriately designed according to the purpose and application, but is usually preferably 10 to 1000 μm, more preferably 100 to 500 μm, and still more preferably 200 to 400 μm.

The diaphragm for an electrochemical element of the present invention preferably has a porosity of 20 to 80% by volume, more preferably 25 to 75% by volume, and still more preferably 30 to 70% by volume. When the porosity is in the above-described range, a membrane having excellent ion conductivity can be obtained by continuously filling the pores of the diaphragm with the electrolytic solution. Moreover, it can be set as the film | membrane excellent also in gas barrier property.
The porosity can be determined by immersing the electrochemical diaphragm of the present invention in ion exchange water at 20 ° C. for a whole day and night and determining the mass of the diaphragm before and after immersion. Specifically, it can be obtained by the following equation.
Porosity (volume%) = (mass of diaphragm after immersion−mass of diaphragm before immersion) / density of ion-exchanged water at 20 ° C./volume of diaphragm × 100

2. Method for producing diaphragm for electrochemical device The method for producing the diaphragm for electrochemical device of the present invention is not particularly limited, and the organic layer forming material containing the inorganic compound particles and the binder polymer described above is rolled on the support. Apply a known method for forming a film, such as a method of forming a film by rolling with a flat plate press, a method of forming a film by rolling with a flat plate press, etc., an injection molding method, an extrusion molding method, a casting method, etc. Can do. Further, as a method for efficiently producing a porous membrane for electrochemical devices, a non-solvent induced phase separation method is preferably exemplified.

Examples of the method for producing a porous diaphragm for electrochemical devices by a non-solvent induced phase separation method include a method including the following steps (1) and (2).
(1) Step of preparing an organic layer forming material containing inorganic compound particles and a binder polymer (2) Step of forming an organic layer on a support using the organic layer forming material Manufacture of such a diaphragm for an electrochemical device A method of preparing an organic layer forming material containing inorganic compound particles and a binder polymer (hereinafter also referred to as “step (1)”), and a support using the organic layer forming material. A method for producing a diaphragm for an electrochemical device comprising a step of forming an organic layer (hereinafter also referred to as “step (2)”) is also one of the preferred embodiments in the present invention. Below, each process is demonstrated.

Process (1)
In the method for producing a diaphragm for an electrochemical device of the present invention, first, an organic layer forming material containing the above-described inorganic compound particles and a binder polymer is prepared.
The method for preparing the organic layer forming material is not particularly limited as long as it is a method capable of mixing the inorganic compound particles and the binder polymer, and a known mixing method can be applied.

When mixing the inorganic compound particles and the binder polymer, the inorganic compound particles and the binder polymer and a solvent may be mixed simultaneously if necessary, or a dispersion (slurry) in which the inorganic compound particles are dispersed in the solvent is prepared in advance. The binder polymer may be added to and mixed with the dispersion, or a solution in which the binder polymer is dissolved in a solvent may be prepared, and the solution and the dispersion may be mixed. Among them, in terms of being able to mix the inorganic compound particles and the binder polymer so as to be even more uniform, a dispersion in which the inorganic compound particles are dispersed in a solvent is prepared in advance, and the binder polymer in the dispersion, or It is preferable to add and mix the solution which melt | dissolved the binder polymer in the solvent.

The mixing method is not particularly limited, and known mixing and dispersion means such as a method using a mixer, a ball mill, a jet mill, a disper, a sand mill, a roll mill, a pot mill, a paint shaker, or the like can be applied.

The solvent for dispersing the inorganic compound particles is not particularly limited as long as it has a property capable of dissolving the binder polymer. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide and the like can be mentioned. These solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them. Among these, N-methyl-2-pyrrolidone is preferable in that the dispersibility of the inorganic compound particles is further improved.

The content of the inorganic compound particles in the dispersion obtained by dispersing the inorganic compound particles in a solvent is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, and 40 to 50% by mass. More preferably.

The solvent used in the solution in which the binder polymer is dissolved is not particularly limited as long as it has a property capable of dissolving the binder polymer, and examples thereof include the same solvents as those for dispersing the inorganic compound particles. Can do. These solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them. Among these, the same solvent as the solvent used for the preparation of the dispersion is preferable in that the inorganic compound particles and the binder polymer can be mixed and dispersed so as to be more uniform.

The content of the binder polymer in the solution in which the binder polymer is dissolved is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and still more preferably 20 to 30% by mass. .

An organic layer forming material may be prepared by appropriately mixing the dispersion and the binder polymer or a solution in which the binder polymer is dissolved in accordance with the purpose and application of the obtained diaphragm for an electrochemical device.

Process (2)
In the method for producing a diaphragm for an electrochemical element of the present invention, an organic layer is then formed on a support using the organic layer forming material obtained in step (1).
A method for forming an organic layer on a support using the organic layer forming material is not particularly limited. However, the following step (2) can be used because a porous diaphragm for an electrochemical element can be efficiently produced. -1) to (2-3) are preferably included.
(2-1) The process of forming the coating film of the said organic layer forming material on a support body,
(2-2) a step of solidifying the coating film by bringing the coating film into contact with a non-solvent; and (2-3) a step of obtaining an organic layer by drying the solidified coating film.

Thus, the step of forming the organic layer includes a step of forming a coating film of the organic layer forming material on a support, a step of solidifying the coating film by contacting the coating film with a non-solvent, and An embodiment including the step of obtaining the organic layer by drying the solidified coating film is also one of the preferred embodiments in the method for producing a diaphragm for an electrochemical device of the present invention.

Step (2-1)
Examples of a method for forming a coating film of the organic layer forming material on a support include, for example, a method of applying the organic layer forming material obtained above on a substrate, and a substrate in the organic layer forming material. Examples of the method include a method of obtaining a base material that is immersed in the organic layer forming material or impregnated with the organic layer forming material. Especially, the method of apply | coating the said organic layer forming material on a support body at the point which can form a coating film simply is preferable.

The method for applying the resin mixture onto the substrate is not particularly limited, and known application means such as a method using die coating, spin coating, gravure coating, curtain coating, spray, applicator, coater, etc. are applied. be able to.

In the case of producing a diaphragm for an electrochemical element, which is a composite in which an organic layer containing inorganic compound particles and a binder polymer and a support are integrated, the organic layer forming material is applied onto a substrate, and the coating is applied. The support may be placed on the liquid and the support may be impregnated with the coating liquid.

The coating amount of the organic layer forming material is not particularly limited, and may be set as appropriate so that the thickness of the obtained diaphragm for an electrochemical element becomes a thickness according to the purpose and application.

Step (2-2)
Next, the coating film is brought into contact with a non-solvent to solidify the coating film.
By bringing the coating film into contact with a non-solvent, the non-solvent diffuses in the coating film, and the binder polymer that does not dissolve in the non-solvent coagulates. On the other hand, the solvent in the coating film that can be dissolved in the non-solvent is eluted from the coating film. When such phase separation occurs, the binder polymer is solidified and a porous organic layer is formed.
Examples of the method of bringing the coating film into contact with the non-solvent include a method of immersing the coating film in the non-solvent (coagulation bath).

The non-solvent is not particularly limited as long as it does not substantially dissolve the binder polymer. Examples thereof include ion-exchanged water; lower alcohols such as methanol, ethanol, propyl alcohol; or a mixed solvent thereof. Among them, ion-exchanged water is preferable from the viewpoints of economy and drainage treatment. The non-solvent may contain a small amount of a solvent similar to the solvent contained in the coating film in addition to the components described above.

It is preferable that the usage-amount of the said non-solvent is 50-10000 mass% with respect to 100 mass% of solid content of the said coating film, ie, organic layer forming material. More preferably, it is 100-5000 mass%, More preferably, it is 200-1000 mass%. In order to adjust the porosity of the obtained diaphragm for electrochemical devices to a preferable range, it is preferable to use a non-solvent in the above-described ratio.

Step (2-3)
The organic layer is obtained by drying the solidified coating film.
By drying the coating film solidified in the step (2-2) and removing the non-solvent, a diaphragm for an electrochemical element in which a porous organic layer is formed on a support can be obtained.
It does not specifically limit as a drying method, It can carry out using well-known drying means, such as heat drying, hot air drying, and vacuum drying.
As drying temperature, 60-80 degreeC is preferable.
Although it does not specifically limit as drying time, What is necessary is just to design suitably according to the shape of a diaphragm, a magnitude | size, etc., Usually, 2 to 120 minutes, Preferably it is 5 to 60 minutes, More preferably, it is 10 to 30 minutes.

As described above, the diaphragm for an electrochemical element of the present invention can be easily produced by the steps (1) and (2) described above.

3. Applications The diaphragm for an electrochemical element of the present invention has excellent adhesion between the organic layer and the support described above, and excellent gas barrier properties. The diaphragm for electrochemical devices of the present invention can exhibit excellent ion permeability and gas barrier properties when applied to a diaphragm for alkaline water electrolysis, for example. Moreover, when it applies to a battery separator, the production | generation of a dendride can fully be suppressed and a long cycle life can be exhibited. Thus, the diaphragm for electrochemical elements of the present invention is particularly preferably used for a diaphragm for alkaline water electrolysis and a battery separator.
Below, the preferable aspect of the diaphragm for alkaline water electrolysis and the battery separator which used the diaphragm for electrochemical elements of this invention is demonstrated.

3-1. Diaphragm for alkaline water electrolysis The diaphragm for an electrochemical element of the present invention can be suitably used as a diaphragm for alkaline water electrolysis. That is, a diaphragm for alkaline water electrolysis comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support is a hydrocarbon-based hydrocarbon having a hydrophilic functional group. A diaphragm for alkaline water electrolysis, which is a porous body, is also a preferred embodiment of the present invention.

Examples of the inorganic compound particles in the membrane for alkaline water electrolysis include those similar to the inorganic compound particles in the above-mentioned “membrane for electrochemical devices”, but in particular, inorganic components are not easily eluted in an alkaline solution. In this respect, magnesium hydroxide, magnesium oxide, zirconium oxide, titanium oxide, or molybdenum oxide is more preferable.

The average particle diameter of the inorganic compound particles is preferably from 0.05 to 2.0 μm, more preferably from 0.1 to 1.5 μm, in view of good dispersibility with the binder polymer. More preferably, it is 0.2-1.0 micrometer. The average particle diameter can be determined by the same method as the method for measuring the average particle diameter of the inorganic compound particles in the “membrane for electrochemical devices” described above.

Examples of the shape of the inorganic compound particles include those similar to the inorganic compound particles in the “membrane for electrochemical devices” described above.

The said inorganic compound particle | grains may be used individually by 1 type among the things mentioned above, and may be used in combination of 2 or more type.

As content of the said inorganic compound particle in the said diaphragm for alkaline water electrolysis, 30-90 mass% is preferable, 32-85 mass% is more preferable, and 35-80 mass% is still more preferable.

Examples of the binder polymer in the membrane for alkaline water electrolysis include those similar to the binder polymer in the above-mentioned “membrane for electrochemical devices”. Among them, an aromatic hydrocarbon group-containing polymer is preferable, and polysulfone , Polyethersulfone, and at least one selected from the group consisting of polyphenylsulfone are more preferable.

As content of the said binder polymer in the said diaphragm for alkaline water electrolysis, 1-40 mass% is preferable, 5-35 mass% is more preferable, 7-30 mass% is still more preferable.

The membrane for alkaline water electrolysis preferably contains 20 to 40 parts by mass of binder polymer, more preferably 22 to 38 parts by mass, and preferably 25 to 35 parts by mass with respect to 100 parts by mass of the inorganic compound particles. Further preferred.

Examples of the support in the diaphragm for alkaline water electrolysis include those similar to the support in the aforementioned “membrane for electrochemical elements”.
Among them, the material for the support in the diaphragm for alkaline water electrolysis preferably contains at least one resin selected from the group consisting of polypropylene, polyethylene, and polyphenylene sulfide, and is selected from the group consisting of polypropylene and polyethylene. More preferably, it comprises at least one selected resin.

As a form of the support in the diaphragm for alkaline water electrolysis, a nonwoven fabric, a woven fabric, or a mesh is preferable.

The thickness of the support in the membrane for alkaline water electrolysis is preferably 30 to 300 μm, more preferably 50 to 250 μm, and still more preferably 100 to 200 μm.

In the diaphragm for alkaline water electrolysis, the organic layer may be formed on one side of the support or on both sides.
Moreover, it is preferable that the said organic layer and the said support body are composites with which at least one part was integrated, and the intensity | strength and toughness of a diaphragm for alkaline water electrolysis can be improved by setting it as the said composite_body | complex.

The porosity of the membrane for alkaline water electrolysis is preferably 20 to 80% by volume, more preferably 25 to 75% by volume, and still more preferably 30 to 70% by volume. The porosity can be measured by the same method as the method for measuring the porosity in the above-mentioned “membrane for electrochemical devices”.

The thickness of the membrane for alkaline water electrolysis is preferably 50 to 1000 μm, more preferably 100 to 500 μm, and still more preferably 200 to 400 μm.

Examples of the method for producing the diaphragm for alkaline water electrolysis include the same method as the method for producing the above-mentioned “membrane for electrochemical elements”. Among these, the non-solvent induced phase separation method is preferable in that a porous membrane can be efficiently formed.

The diaphragm for alkaline water electrolysis is used as a member of an alkaline water electrolysis apparatus. Examples of the alkaline water electrolysis apparatus include an anode, a cathode, and an alkaline water electrolysis diaphragm disposed between the anode and the cathode. More specifically, the alkaline water electrolysis apparatus has an anode chamber where an anode is present and a cathode chamber where a cathode is present, which are separated by the diaphragm for alkaline water electrolysis. Examples of the anode and the cathode include known electrodes including a conductive substrate containing nickel or a nickel alloy.

The method of electrolyzing water using the alkaline water electrolysis apparatus provided with the above diaphragm for alkaline water electrolysis is not particularly limited, and can be performed by a known method. For example, it can be performed by filling the alkaline water electrolysis apparatus provided with the above-described alkaline water electrolysis diaphragm with an electrolytic solution and applying a current in the electrolytic solution.

As the electrolytic solution, an alkaline aqueous solution in which an electrolyte such as potassium hydroxide or sodium hydroxide is dissolved is used. The concentration of the electrolyte in the electrolytic solution is not particularly limited, but is preferably 20 to 40% by mass in that the electrolytic efficiency can be further improved.

Moreover, as temperature in the case of performing electrolysis, 50-120 degreeC is preferable and 80-90 degreeC is more preferable at the point which the ionic conductivity of electrolyte solution improves more and electrolysis efficiency can improve further. The current application condition can be performed by a known condition / method.

3-2. Battery separator The diaphragm for an electrochemical element of the present invention can also be suitably used as a battery separator. That is, a battery separator including an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support is a hydrocarbon-based porous body having a hydrophilic functional group. A battery separator characterized by the above is also one of the preferred embodiments of the present invention.

Examples of the inorganic compound particles in the battery separator include those similar to the inorganic compound particles in the “membrane for electrochemical devices” described above. Especially, the compound containing the hydroxide or hydroxide layer containing magnesium is preferable at the point that ion conductivity is favorable, and magnesium hydroxide or hydrotalcite is more preferable.

The average particle diameter of the inorganic compound particles in the battery separator is preferably 0.001 to 10 μm, more preferably 0.01 to 5 μm, in view of good dispersibility with the binder. More preferably, it is 1-4 micrometers. The average particle diameter can be determined by the same method as the method for measuring the average particle diameter of the inorganic compound particles in the “membrane for electrochemical devices” described above.

As content of the inorganic compound particle in the said battery separator, 30-99 mass% is preferable, 40-95 mass% is more preferable, 45-90 mass% is still more preferable.

As a binder polymer in the said battery separator, the thing similar to the binder polymer in the "membrane for electrochemical elements" mentioned above can be mentioned. Especially, at least 1 sort (s) selected from the group which consists of a conjugated diene type polymer, a halogen atom containing polymer, and a (meth) acrylic-type polymer is preferable at the point which can extend a lifetime of a battery.

The binder polymer preferably has a glass transition temperature (Tg) of −40 ° C. or higher and 50 ° C. or lower. When the Tg of the binder polymer is less than −40 ° C., the mechanical strength of the battery separator is insufficient, and the dendrite suppressing effect may be lowered. Moreover, when Tg exceeds 50 ° C., the battery separator becomes too brittle. For example, when the battery is formed, cracks or the like may occur in the battery separator, which may reduce the life performance of the battery. In the battery separator of the present invention, in order to suppress the formation of voids due to the aggregation of inorganic compound particles, the components contained in the organic layer forming material are sufficiently kneaded to suppress the aggregation of inorganic compound particles. The inorganic compound particles and the binder polymer components are preferably in a uniform state. When the Tg of the binder polymer is -40 ° C. or higher and 50 ° C. or lower, the kneaded product at the time of kneading with the inorganic compound particles becomes more appropriate fluidity, and the aggregates of the inorganic compound particles are crushed or the organic layer is formed. The components contained in the material can be made more uniform. The Tg of the binder polymer is more preferably −15 ° C. or higher and 30 ° C. or lower, and further preferably −10 ° C. or higher and 20 ° C. or lower.
The Tg of the binder polymer was obtained by applying a polymer to a glass plate and drying it at 120 ° C. for 1 hour to form a polymer film. The obtained polymer film was subjected to a differential scanning calorimeter (device name: thermal analyzer DSC3100S, BRVKER).

As content of the binder polymer in the said battery separator, 1-70 mass% is preferable, and 5-60 mass% is more preferable.

The battery separator preferably contains 1 to 67 parts by mass of binder polymer, more preferably 2 to 54 parts by mass, and still more preferably 3 to 43 parts by mass with respect to 100 parts by mass of the inorganic compound particles.

Examples of the support in the battery separator include those similar to the support in the “membrane for electrochemical devices” described above.
Especially, as a material of the support body in the said battery separator, polyolefin type, polyphenylene sulfide type, or polyvinyl alcohol type is preferable.

In the battery separator, the organic layer may be formed on one surface of the support, or may be formed on both surfaces. Moreover, the composite body with which the said organic layer and the said support body were integrated may be sufficient.

The thickness of the battery separator is preferably 10 to 1000 μm, more preferably 15 to 800 μm, and still more preferably 20 to 500 μm.

Examples of the method for producing the battery separator include the same method as the method for producing the above-mentioned “membrane for electrochemical devices”.

The said battery separator can be used suitably as a battery separator comprised including a positive electrode, a negative electrode, and electrolyte solution.
The positive electrode is not particularly limited as long as it contains an active material usually used as a positive electrode active material for a primary battery or a secondary battery, and a known one can be used.
As the active material of the positive electrode, for example, oxygen (when oxygen is the positive electrode active material, the positive electrode is a perovskite type compound capable of reducing oxygen or oxidizing water, a cobalt-containing compound, an iron-containing compound, a copper-containing compound, manganese Containing compound, vanadium containing compound, nickel containing compound, iridium containing compound, platinum containing compound; palladium containing compound; gold containing compound; silver compound; air electrode composed of carbon containing compound etc.); nickel oxyhydroxide, water Nickel-containing compounds such as nickel oxide and cobalt-containing nickel hydroxide; manganese-containing compounds such as manganese dioxide; silver oxide; lithium-containing compounds such as lithium cobaltate; iron-containing compounds; and zinc species such as metal zinc and zinc oxide It is done.

The negative electrode is not particularly limited as long as it contains an active material usually used as a negative electrode active material for a primary battery or a secondary battery, and a known one can be used.
As the negative electrode active material, carbon, lithium, sodium, magnesium, zinc, nickel, tin, silicon-containing materials, and the like that are usually used as negative electrode active materials for batteries can be used. Especially, a zinc compound is preferable at the point which can improve the performance of a separator further.

The electrode constituting the battery can be manufactured by forming an active material layer on the current collector.
Current collectors that make up the electrode include (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, punched brass , Nickel foil, corrosion resistant nickel, nickel mesh (expanded metal), punching nickel, metallic zinc, corrosion resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric with conductivity; Copper, copper foil, copper mesh (expanded metal), copper foil, punched copper, brass and other copper alloys, brass foil, brass mesh (expanded metal) with Sn, Pb, Hg, Bi, In, Tl, brass, etc. added ) ・ Foamed brass ・ Punching brass ・ Nickel foil ・ Corrosion resistant nickel ・ Nickel mesh (Expanded) Tal), punched nickel, metallic zinc, corrosion resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric; plated with Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, brass, etc. (Electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, punched brass, nickel foil, corrosion-resistant nickel, nickel Mesh (expanded metal), punched nickel, metallic zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric; silver; current collectors and containers for alkaline (storage) batteries and zinc-air batteries The material etc. which are used as are mentioned.

The electrolytic solution constituting the battery is not particularly limited as long as it is usually used as the electrolytic solution for the battery. Examples thereof include a water-containing electrolytic solution and an organic solvent-based electrolytic solution, and a water-containing electrolytic solution is preferable. The water-containing electrolytic solution refers to an electrolytic solution using only water as an electrolytic solution raw material (aqueous electrolytic solution) or an electrolytic solution using a solution obtained by adding an organic solvent to water as an electrolytic solution raw material.

As the aqueous electrolyte, an alkaline electrolyte is preferable. Examples of the alkaline electrolyte include potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, zinc sulfate aqueous solution, zinc nitrate aqueous solution, zinc phosphate aqueous solution, and zinc acetate aqueous solution. The aqueous electrolyte solution can be used alone or in combination of two or more.

Moreover, the said water containing electrolyte solution may contain the organic solvent used for an organic solvent type electrolyte solution. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxymethane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethyl sulfoxide, sulfolane, acetonitrile, Examples include benzonitrile, ionic liquid, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, fluorine-containing polyethylene glycols and the like. The organic solvent electrolyte can be used alone or in combination of two or more. The electrolyte of the organic solvent-based electrolytic solution is not particularly limited, but LiPF ₆ , LiBF ₄ , LiB (CN) ₄ , lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethylsulfonyl) imide ( LiTFSI) and the like are preferable.

In the case of a water-containing electrolyte containing an organic solvent-based electrolyte, the content of the water-based electrolyte is preferably 10-99.9% by mass with respect to a total of 100% by mass of the aqueous electrolyte and the organic solvent-based electrolyte. More preferably, it is 20-99.9 mass%.

The battery type to which the battery separator can be applied is as follows: primary battery; chargeable / dischargeable secondary battery (storage battery); mechanical charge type battery (battery in which zinc negative electrode is mechanically replaced); third pole type The battery (a battery constituted by using a negative electrode, an electrode suitable for charging, and an electrode suitable for discharging), a fuel cell, or the like may be used, but a secondary battery or a fuel cell is preferable. .
The type of the battery is not particularly limited, but is preferably a battery that uses an alkaline electrolyte, such as an alkaline dry battery, a silver oxide battery, a manganese-zinc battery, a nickel-zinc battery, a fuel battery, and an air battery.

As described above, the diaphragm for an electrochemical element of the present invention is excellent in the adhesion between the organic layer and the support, and exhibits excellent gas barrier properties. It also has an excellent long cycle life. The diaphragm for electrochemical devices of the present invention is particularly suitably used as a diaphragm for alkaline water electrolysis or a battery separator.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

<Example 1>
Magnesium hydroxide (manufactured by Kyowa Chemical Industry Co., Ltd., product number 200-06H, average particle size 0.54 μm) and N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed so as to have a mass ratio of 1: 1. A magnesium hydroxide dispersion was prepared by carrying out a dispersion treatment at room temperature for 6 hours in a pot mill containing zirconia media balls.
A polysulfone resin solution by heat-dissolving polysulfone resin (manufactured by BASF, product number Ultra Zone S3010) in N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) at a concentration of 30% by mass at 80 to 100 ° C. Was prepared.
The magnesium hydroxide dispersion and the polysulfone resin solution obtained above were weighed so that the polysulfone resin (PSU) was 33 parts by mass with respect to 100 parts by mass of magnesium hydroxide, and a revolving mixer (made by Shinky Corporation) No. Awatori Nertaro ARE-500) and mixed at room temperature at 1000 rpm for about 10 minutes. The obtained liquid mixture was filtered through SUS 200 mesh to obtain a coating liquid (organic layer forming material).
On a PET film, a coating liquid is applied with an applicator, and a polypropylene non-woven fabric treated with fluorine gas and sulfurous acid gas (oxygen element 22.1 atm% relative to carbon element 100 atm%, fluorine element 8.3 atm%, The non-woven fabric was completely impregnated with the coating liquid by contacting with sulfur element (3.3 atm%, thickness 160 μm). Thereafter, the nonwoven fabric impregnated with the coating solution was bathed in water at room temperature for 10 minutes to solidify the coating solution to form a film, and the membrane was peeled off from the PET film together with the nonwoven fabric in water. After the water bath, the obtained membrane was dried with a dryer at 80 ° C. for 30 minutes to obtain a diaphragm for an electrochemical device comprising a composite of a nonwoven fabric and a membrane containing magnesium hydroxide and a polysulfone resin. . The total thickness of the obtained diaphragm was 300 μm.

(1. Measurement of bubble point value)
About the diaphragm obtained above, the bubble point value was measured using the liquid porometer (made by Porous Materials). Specifically, a 2.5 cmφ diaphragm was immersed in ion-exchanged water at room temperature for 1 hour to be sufficiently wetted, and then a fluorinated solvent Galwick (manufactured by Porous Materials) was filled on the diaphragm. The gas pressure for the diaphragm was increased, the liquid film of water was destroyed, and the gas pressure when Galwick permeated the membrane and observed its weight with a balance was taken as the bubble point value. The bubble point value of the diaphragm was 6.8 bar.

(2. Charge / discharge cycle test of nickel metal hydride battery)
Nickel hydroxide powder (Tanaka Chemical Co. Coated product) and polyvinylidene fluoride (PVDF) resin (Kureha KF polymer) were mixed at a weight ratio of 95: 5 to make a slurry, and then used as the current collector nickel foam. The nickel positive electrode was made by impregnation and pressing using a flat plate press after drying. Similarly, a hydrogen negative electrode was prepared using hydrogen storage alloy powder instead of nickel hydroxide powder. The diaphragm obtained above was inserted as a separator between the nickel positive electrode and the hydrogen negative electrode to constitute a nickel hydrogen battery having an electrode size of 2 cm × 2 cm. 6MKOH was injected as an electrolytic solution, and a charge / discharge cycle test was performed at a rate of 1C with respect to a theoretical capacity of 75 mAh. As a result, the battery could be driven without problems even after 500 cycles.

(3. Nickel zinc battery charge / discharge cycle test)
2. In the above nickel-metal hydride battery, except that a zinc negative electrode was made using zinc oxide powder instead of the hydrogen storage alloy to constitute a nickel-zinc battery, the above 2. Similarly to the nickel metal hydride battery, a charge / discharge cycle test was performed under the same conditions using the diaphragm obtained above as a separator for an electrochemical element. As a result, a cycle life of 200 cycles was observed.

<Example 2>
Polypropylene non-woven fabric obtained by hydrophilizing non-woven fabric with fluorine gas and sulfurous acid gas as support (oxygen element 10.4 atm%, fluorine element 3.9 atm%, sulfur element 0.8 atm%, thickness 90 μm with respect to 100 atm% of carbon element) A diaphragm for an electrochemical device (total thickness 300 μm) was prepared in the same manner as in Example 1 except that was used and evaluated in the same manner. The bubble point value of the obtained diaphragm was 5.1 bar. In the charge / discharge cycle test of the nickel zinc battery, a cycle life of 400 cycles was observed.

<Example 3>
The same as Example 1 except that a polyphenylene sulfide nonwoven fabric (oxygen element 12.1 atm%, sulfur element 12.6 atm%, thickness 220 μm with respect to 100 atm% carbon) was used as the support. The membrane for electrochemical devices (total thickness 300 μm) was prepared by the method described above and evaluated in the same manner. The bubble point value of the obtained diaphragm was 7.2 bar. In the charge / discharge cycle test of the nickel zinc battery, a cycle life of 220 cycles was observed.

<Example 4>
Example 1 except that a polyphenylene sulfide non-woven fabric obtained by surface-treating a non-woven fabric with a surfactant (oxygen element 29.9 atm%, sulfur element 4.0 atm%, thickness 160 μm with respect to 100 atm% carbon) was used as a support. A diaphragm for an electrochemical element (total thickness 300 μm) was prepared in the same manner, and evaluated in the same manner. The resulting membrane had a bubble point value of 6.5 bar. In the charge / discharge cycle test of the nickel zinc battery, a cycle life of 190 cycles was observed.

<Example 5>
100 parts by mass of magnesium hydroxide particles (manufactured by Kyowa Chemical Industry Co., Ltd., product number 200-06H, average particle size 0.54 μm), 3 parts by mass of a polyacrylate aqueous solution (non-volatile content 40%) and 42 parts by mass of ion-exchanged water are measured. The resulting mixture was dispersed for 1 hour using a sand mill, and then filtered to obtain a magnesium hydroxide particle aqueous dispersion.
After weighing and mixing 50 parts by mass of the obtained magnesium hydroxide particle aqueous dispersion and 33 parts by mass of a carboxy-modified styrene-butadiene polymer aqueous dispersion (nonvolatile content: 48%, Nalstar SR-152 manufactured by Nippon A & L Co., Ltd.) Filtration and vacuum defoaming were performed to obtain an organic layer forming material.
The obtained organic layer forming material was coated on a polyethylene terephthalate (PET) film with a comma coater so that the measured value of the organic layer forming material at the time of drying was 9.0 mg / cm ^2. Hydrophilic polypropylene non-woven fabric (oxygen element 20.9 atm%, fluorine element 10.2 atm%, sulfur element 3.9 atm%, thickness 160 μm with respect to 100 atm% carbon element) was contacted and then dried, from a PET film The membrane for an electrochemical device in which the nonwoven fabric and the coating film were integrated was obtained by peeling the coating film together with the nonwoven fabric. The obtained diaphragm was evaluated in the same manner as in Example 1. The bubble point value of the obtained diaphragm was 8.5 bar. In the charge / discharge cycle test of the nickel zinc battery, 170 cycle life was observed.

<Example 6>
A hydrotalcite aqueous dispersion was obtained in the same manner as in Example 5 except that hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., product number DHT-6, average particle size 0.20 μm) was used as the inorganic particles. An organic layer was formed using 50 parts by mass of this hydrotalcite aqueous dispersion and 21 parts by mass of a carboxy-modified styrene-butadiene polymer aqueous dispersion (non-volatile content: 48%) prepared in the same manner as in Example 5. A diaphragm for an electrochemical device was obtained in the same manner as in Example 5 except that the material was obtained. About the obtained diaphragm, evaluation similar to Example 1 was performed. The bubble point value of the obtained diaphragm was 7.5 bar. In the charge / discharge cycle test of the nickel zinc battery, a cycle life of 220 cycles was observed.

<Comparative Example 1>
A diaphragm for an electrochemical element (total thickness 400 μm) in the same manner as in Example 1 except that a non-hydrophilic polypropylene nonwoven fabric (oxygen element 1 atm% or less, 380 μm thickness relative to 100% carbon element) was used as the support. Got. About the obtained diaphragm, evaluation similar to Example 1 was performed. The bubble point value of the obtained diaphragm was 0.4 bar. In the charge / discharge cycle test of the nickel-metal hydride battery and the nickel-zinc battery, the cycle life was less than 50 cycles.

From the above results, it was confirmed that the diaphragms for electrochemical elements of Examples 1 to 6 had a very high bubble point value and excellent gas barrier properties as compared with the diaphragm of Comparative Example 1. Moreover, it was recognized that the diaphragms for electrochemical elements of Examples 1 to 6 have a very long cycle life and excellent reliability as compared with the diaphragm of Comparative Example 1.

Claims (3)

A diaphragm for an electrochemical device comprising an organic layer containing a binder polymer and a support,
The organic layer further includes inorganic compound particles,
The support is a hydrocarbon-based porous body having a hydrophilic functional group,
The hydrocarbon porous body having a hydrophilic functional group is characterized in that, in an element concentration measured by X-ray photoelectron spectroscopy (ESCA), an oxygen element concentration with respect to 100 atm% of carbon element is 10 atm% or more. A diaphragm for electrochemical devices. The hydrocarbon-based porous body having a hydrophilic functional group further has a sulfur element concentration of 0.5 atm% or more with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). The diaphragm for an electrochemical element according to claim 1. The hydrocarbon-based porous body having a hydrophilic functional group further has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of carbon element at an element concentration measured by X-ray photoelectron spectroscopy (ESCA). The diaphragm for an electrochemical element according to claim 1 or 2.