JP7151425B2 - Method for producing porous layer, porous layer and electrode - Google Patents

Description

The present invention relates to a method for producing a porous layer, a porous layer and an electrode.

Patent Document 1 describes a method for producing a crosslinked polyolefin open-cell body in which a foaming agent and a crosslinking agent are added to polyolefin. Patent Document 2 describes a porous hollow fiber membrane formed by thermally induced phase separation of a polymer compound and a solvent.

Patent Document 3 describes a method for producing a porous body in which an epoxy resin and a curing agent are dissolved in a porogen, polymerized by heating, and then the porogen is removed. Patent Literature 4 and Patent Literature 5 describe removing the porogen by washing and extraction. Patent Document 6 describes a porous membrane obtained using a photoinitiator.

An object of the present invention is to obtain a porous layer and an electrode having excellent permeability.

The present invention comprises a preparatory step of preparing a porous forming layer containing a polymerizable compound, a polymerization initiator and a solvent on a substrate, and activating the polymerization initiator to polymerize the polymerizable compound to form a porous layer. a polymerization step of forming a skeleton; and a solvent removal step of removing a solvent contained in the porous forming layer to obtain a porous layer, wherein the substrate is a porous substrate, and the porous layer is A method for producing a porous film having a co-continuous structure, wherein the polymerization step is performed at a temperature lower than the temperature in the solvent removal step.

The present invention is a porous layer formed by a continuous crosslinked structure, wherein the difference between the porosity of the cross section near the surface and the porosity of the cross section near the bottom is less than 10%. The present invention also provides an electrode comprising a battery electrode active material layer containing an active material, and the porous layer formed on the battery electrode active material layer.

According to the present invention, a porous layer and an electrode having excellent permeability can be obtained.

1 shows an apparatus for realizing a method for producing a phase-separated porous membrane, which is one embodiment of the present invention. It is a figure which shows the detail of the superposition|polymerization process part 20 in this embodiment. 1 is a surface SEM photograph of a porous membrane obtained in Example 1 of the present embodiment. 1 is a cross-sectional SEM photograph of a porous membrane obtained in Example 1 of the present embodiment. It is a surface SEM photograph of the porous membrane obtained in Example 6 of the present embodiment. It is a cross-sectional SEM photograph of the porous membrane obtained in Example 6 of the present embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

Porous structures can be used for various applications. For example, by selecting a porous structure with suitable shapes, sizes, and sizes of pores and skeleton portions, it is possible to separate substances by allowing only a specific substance to permeate or block.

In addition, by utilizing the vast surface area and void volume of the porous structure, it can be utilized as an efficient reaction field and storage field for gases and liquids taken in from the outside.

When used as a material separation, a reaction field, or a storage field as described above, the porous structure must have a structure that easily takes in liquids and gases from the outside, and must have sufficiently high resistance to heat and chemicals. It is important to be able to maintain the porous skeleton and express the function even in the situation.

As a method for obtaining a porous structure, there is a method using a foaming agent, but the resulting porous body tends to have low communication properties and low gas and liquid permeability.

It is also possible to obtain a porous structure by layering fine particles, but this method tends to form a close-packed structure, making it difficult to obtain a porous structure with high voids and high gas or liquid permeability. In addition, it is common to use a binder to bind particles together, and the use of a binder causes further reduction in voids.

A porous body formed by phase separation has a high porosity, and since the pore regions have communication properties, it is easy to obtain a structure that is advantageous for gas and liquid permeation.

It is thought that this will exert sufficient effects even if the porous structure is in the form of a thin film formed on some kind of base material. If it can be formed without any restrictions, it can be used as an insulating layer for batteries, for example, and the field of utilization of the above applications will be dramatically improved.

However, when a polymer is used, chemical resistance and heat resistance are low due to the non-crosslinked polymer skeleton in general thermal induction and poor solvent induction.

On the other hand, a porous polymer body having a crosslinked structure can be obtained by a polymerization reaction and is excellent in chemical resistance and heat resistance, but securing sufficient permeability is a problem.

In the conventional process for producing a phase-separated porous membrane using a polymerization reaction, there is a process in which solubility and compatibility are lowered due to progress of polymerization triggered by heat. However, it takes a long time to form a porous film, and the porous film obtained tends to have a coarse structure with a large variation. That is, there was a large variation in permeability.

Furthermore, there are methods of removing the phase separation agent, such as washing and extraction, but there are problems in productivity due to the accompanying increase in materials used and the limitation of porous supports having chemical resistance.

As a manufacturing method with high productivity, a method using light can be considered. However, generally obtained porous membranes tend to have small surface voids. This is effective as a glossy ink-receiving layer, but when it is used for the applications described above, it is difficult to obtain sufficient functions and effects because the permeability to gases and liquids is greatly impaired.

That is, in the conventional method for producing a phase-separated porous membrane using a polymerization reaction, the porous formation time is long, the productivity is not sufficient, and the permeability varies with the production method that proceeds with heat as a trigger. In addition, in the manufacturing method using light, the porous formation time is short and the productivity is high, but the permeability is not sufficient. Therefore, the present embodiment is intended to solve the above problems, and an object thereof is to ensure excellent permeability in a porous layer (membrane) produced by phase separation using a polymerization reaction.

FIG. 1 shows an apparatus for realizing a method for producing a phase-separated porous membrane, which is one embodiment of the present invention.

(Manufacturing apparatus 100)
The apparatus 100 for producing a phase-separated porous membrane is an apparatus for producing a phase-separated porous membrane using a membrane-forming stock solution comprising a polymerizable compound, a polymerization initiator, and a solvent.

The manufacturing apparatus 100 includes a printing process section 10 including a preparatory process for forming and preparing a porous forming layer composed of a polymerizable compound, a polymerization initiator, and a solvent on a printing substrate 4, and a polymerization initiator for the porous forming layer. is activated to form a porous skeleton by polymerizing a polymerizable compound to obtain a porous precursor 6, and a heating process section including a heating step of heating the porous precursor 6 30 to obtain a porous layer (porous membrane).

The manufacturing apparatus 100 also includes a transport section 5 for transporting the printing base material 4, and the transport section 5 is set in advance to transfer the printing base material 4 in the order of the printing process section 10, the polymerization process section 20, and the heating process section 30. Convey at speed.

(Printing process section 10)
The printing process section 10 includes a printing device 1a that ejects ink onto the printing substrate 4, an ink container 1b that stores ink, and an ink supply tube 1c that supplies the ink stored in the ink container 1b to the printing device 1a. Prepare.

The ink stored in the ink container 1b is a film-forming stock solution 7 containing a polymerizable compound, a polymerization initiator, and a solvent. 4 is coated with the undiluted solution for film formation 7 to form a porous film-forming layer in the form of a thin film.
The printing apparatus 1a is not particularly limited as long as it can be coated with the film-forming stock solution 7 described later. Examples include spin coating, casting, micro gravure coating, gravure coating, bar coating, and roll coating. , wire bar coating method, dip coating method, slit coating method, capillary coating method, spray coating method, nozzle coating method, gravure printing method, screen printing method, flexographic printing method, offset printing method, reverse printing method, inkjet printing method, etc. Any printing device can be used according to the various printing methods.

The ink container 1b and the ink supply tube 1c can be arbitrarily selected as long as they can stably store and supply the film-forming stock solution 7, which will be described later. It is preferable that the material forming the ink container 1b and the ink supply tube 1c has light shielding properties in the relatively short wavelength regions of ultraviolet and visible light. As a result, the film forming stock solution 7 is prevented from being polymerized by outside light.

Next, the membrane-forming stock solution 7 will be described. The film-forming stock solution consists of a polymerizable compound, a polymerization initiator and a solvent.

(Polymerizable compound)
The polymerizable compound corresponds to a precursor of a resin for forming a porous structure, and may be any resin as long as it is capable of forming a crosslinkable structure by light irradiation or heat. Examples include acrylate resins, Methacrylate resins, urethane acrylate resins, vinyl ester resins, unsaturated polyesters, epoxy resins, oxetane resins, vinyl ethers, resins utilizing ene-thiol reactions, especially structures utilizing radical polymerization due to their high reactivity. From the standpoint of productivity, acrylate resins, methacrylate resins, urethane acrylate resins, and vinyl ester resins, which are easy to form, are preferable.

The resin compound contained in the film-forming stock solution is prepared as a mixture of a polymerizable compound that can be cured by light or heat and a compound that generates radicals or acids by light or heat as an example of a polymerization initiator. can be obtained with

In order to form a porous film by polymerization-induced phase separation, a curable composition (ink) may be prepared by mixing the above mixture with a solvent as a porogen in advance.

Although there are other methods for obtaining porous membranes by phase separation, the use of polymerization-induced phase separation enables the formation of porous membranes having a continuous crosslinked structure, which makes it possible to obtain porous membranes with high resistance to chemicals and heat. can be expected. In addition, compared to other major products, it has the advantages of short process time and easy surface modification.

The polymerizable compound has at least one radically polymerizable functional group. Examples thereof include monofunctional, difunctional, or trifunctional or higher radically polymerizable compounds, functional monomers, and radically polymerizable oligomers. Among these, difunctional or higher radically polymerizable compounds are particularly preferred.

Examples of the monofunctional radically polymerizable compound include 2-(2-ethoxyethoxy)ethyl acrylate, methoxypolyethylene glycol monoacrylate, methoxypolyethylene glycol monomethacrylate, phenoxypolyethylene glycol acrylate, 2-acryloyloxyethyl succinate, 2 -ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexylcarbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol Acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer and the like. These may be used individually by 1 type, or may use 2 or more types together.

Examples of the bifunctional radical polymerizable compound include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1 , 6-hexanediol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol F diacrylate, neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate etc. These may be used individually by 1 type, or may use 2 or more types together.

Examples of the tri- or more functional radically polymerizable compound include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, and caprolactone-modified trimethylolpropane. Triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH-modified glycerol triacrylate, EO-modified glycerol triacrylate, PO-modified glycerol triacrylate, tris(acryloxy ethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxy tetraacrylate, EO-modified phosphoric acid triacrylate, 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate, and the like. These may be used individually by 1 type, or may use 2 or more types together.

(Polymerization initiator)
As an example of the polymerization initiator, a radical generator can be used, and further a photo-radical generator can be used. For example, photoradical polymerization initiators such as Michler's ketone and benzophenone known under the trade names of Irgacure and Darocure, more specific compounds include benzophenone, acetophenone derivatives such as α-hydroxy- or α-aminocetophenone, -aroyl-1,3-dioxolane, benzyl ketal, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, pp'-dichlorobenzophene, pp '-Bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzyl dimethyl ketal, tetramethylthiuram monosulfide, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, azobisisobutyronitrile, benzoin peroxide, di- tert-butyl peroxide, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one , methyl benzoyl formate, zoin isopropyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin alkyl ethers and esters such as benzoin isobutyl ether, benzoin n-butyl ether, benzoin n-propyl, 1-hydroxy-cyclohexyl -phenyl-ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-1,2-diphenylethane -1-one, bis(η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, bis(2, 4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-methyl-1[4-(methylthio)phenyl]-2-morifolinopropan-1-one, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one (Darocur 1173), bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 1-[4-(2-hydroxyethoxy)-phenyl]-2- Hydroxy-2-methyl-1-propane-1-onmo Noacylphosphine oxides, bisacylphosphine oxides or titanocenes, fluorescenes, anthraquinones, thioxanthones or xanthones, lophine dimers, trihalomethyl compounds or dihalomethyl compounds, active ester compounds, organoboron compounds, and the like are preferably used.
Furthermore, a photo-crosslinking radical generator such as a bisazide compound may be contained at the same time.

When the polymerization is accelerated by heat, a thermal polymerization initiator such as AIBN (azobisisobutyronitrile) can be mixed with the photoradical generator. Alternatively, as another embodiment, a thermal polymerization initiator such as AIBN may be mainly used and a photoradical generator may be mixed.

On the other hand, a similar function can be achieved by preparing a mixture of a photoacid generator that generates an acid upon irradiation with light and at least one monomer that polymerizes in the presence of an acid. When such a liquid ink is irradiated with light, the photoacid generator generates an acid, and this acid functions as a catalyst for the cross-linking reaction of the polymerizable compound. Also, the generated acid diffuses within the ink layer. Moreover, acid diffusion and acid-catalyzed cross-linking reactions can be accelerated by heating, and unlike radical polymerization, the cross-linking reactions are not inhibited by the presence of oxygen. The obtained resin layer is also excellent in adhesion as compared with the radical polymerization system.

Polymerizable compounds that crosslink in the presence of an acid include compounds having a cyclic ether group such as an epoxy group, an oxetane group, and an oxolane group; Monomers with cationically polymerizable vinyl bonds, such as molecular weight melamine compounds, vinyl ethers and vinylcarbazoles, styrene derivatives, alpha-methylstyrene derivatives, and vinyl alcohol esters such as vinyl alcohol and acrylic and methacrylic ester compounds. use together.

Examples of photoacid generators that generate acids upon irradiation with light include onium salts, diazonium salts, quinonediazide compounds, organic halides, aromatic sulfonate compounds, bisulfone compounds, sulfonyl compounds, sulfonate compounds, sulfonium compounds, sulfamide compounds, Iodonium compounds, sulfonyldiazomethane compounds, mixtures thereof, and the like can be used.

Among them, it is desirable to use an onium salt as the photoacid generator. Usable onium salts include, for example, fluoroborate anion, hexafluoroantimonate anion, hexafluoroarsenate anion, trifluoromethanesulfonate anion, paratoluenesulfonate anion, and diazonium salt with paranitrotoluenesulfonate anion as a counter ion, phosphonium salts, and sulfonium salts may be mentioned. Photoacid generators can also be used with halogenated triazine compounds.

The photoacid generator may optionally further contain a sensitizing dye. Sensitizing dyes include, for example, acridine compounds, benzoflavins, perylenes, anthracenes, and laser dyes.

In this embodiment, a photoradical generator is used as the polymerization initiator, and a photoacid generator and a thermal polymerization initiator are added as necessary.

(solvent)
Next, the solvent used will be described. Further, in order to form a porous body by polymerization-induced phase separation, it is possible to prepare a mixed solution by mixing a solvent in advance with the polymerizable compound and the compound that generates radicals or acids upon exposure to light. The solvent functions as a porogen to form porous void regions during photopolymerization.

The porogen is capable of dissolving the polymerizable compound and the compound that generates radicals or acids by light, and phase separation occurs during the polymerization of the polymerizable compound and the compound that generates radicals or acids by light. Any liquid substance can be selected as long as it is capable of producing
Examples of porogens include ethylene glycols such as diethylene glycol monomethyl ether, ethylene glycol monobutyl ether and dipropylene glycol monomethyl ether, esters such as γ-butyrolactone and propylene carbonate, and amides such as NN dimethylacetamide.

In addition, liquid substances having relatively large molecular weights such as methyl tetradecanoate, methyl decanoate, methyl myristate and tetradecane tend to function as porogens. In particular, many ethylene glycols have high boiling points. The phase separation mechanism is highly dependent on the porogen concentration for the structures formed. Therefore, the use of the above-mentioned liquid substance makes it possible to form a stable porous body. Moreover, the porogen may be used alone or in combination of two or more.

The viscosity of the resulting film-forming stock solution is preferably 1 to 150 mPa·s, more preferably 5 to 20 mPa·s at 25° C. in consideration of leveling performance from the viewpoint of handling property and ensuring print quality.

Further, the solid content concentration of the polymerizable compound in the film-forming stock solution is preferably 5 to 70% by mass, more preferably 10 to 50% by mass.

If the concentration of the polymerizable compound is higher than the above range, the viscosity of the curable composition (ink) increases, making it difficult to form a porous layer on the surface and inside of the active material. In addition, there is a tendency that the pore diameter becomes as small as several tens of nanometers or less, making it difficult for liquids and gases to permeate. On the other hand, if the concentration of the polymerizable compound is lower than the above, the three-dimensional network structure of the resin is not sufficiently formed, and the porous structure cannot be obtained, or the strength of the obtained porous body is significantly reduced. A trend can be seen.

The thickness of the formed porous film-forming layer is preferably 0.01 to 500 μm, more preferably 0.01 to 100 μm, in consideration of uniformity of light irradiation in the photopolymerization step 20 . If the film thickness is thinner than the above, the surface area of the obtained porous film is small, so that the function of the formation of the porous film cannot be sufficiently obtained. If the film thickness is greater than the above, unevenness in the light and heat used during polymerization tends to occur in the film thickness direction, and it tends to be difficult to obtain a porous structure with small variations in the film thickness direction. Furthermore, the occurrence of irregular and non-uniform structural irregularities in the porous membrane due to the above irregularities in light or heat is not preferable because it causes a decrease in liquid or gas permeability.

(Print base material 4)
Any material, whether transparent or opaque, can be used as the material for the printing substrate of the present invention. That is, transparent substrates include glass substrates, resin film substrates such as various plastic films, and composite substrates thereof, and opaque substrates include silicon substrates, metal substrates such as stainless steel, or laminates thereof. Various substrates can be used, such as

Also, regarding the shape, even if it has a curved surface or an uneven shape, it can be used as long as it is applicable to the printing process section 10, the polymerization process section 20, the drying process, and the removal process section 30. .

However, especially when it is used as an insulating layer for batteries, it is necessary to apply it onto the active material layer previously formed on the electrode substrate.

The electrode substrate is not particularly limited as long as it has planarity and conductivity, and can be suitably used for secondary batteries and capacitors, which are generally electrical storage devices, especially lithium ion secondary batteries. Aluminum foil, copper Foils, stainless steel foils, titanium foils, etched foils obtained by etching them with fine holes, electrode substrates with holes used in lithium ion capacitors, and the like are used. In addition, carbon paper fiber-like electrodes used in power generation devices such as fuel cells may be used in a non-woven or woven flat form, and the perforated electrode substrates having fine holes may also be used. Furthermore, in the case of a solar device, in addition to the above electrodes, a transparent semiconductor thin film such as an indium-titanium oxide or zinc oxide is formed on a flat substrate such as glass or plastic, or a conductive film is formed. A thinly vapor-deposited electrode film can be used.

The active material layer is formed by dispersing a powdery active material or catalyst composition in a liquid, coating the liquid on the electrode substrate, fixing it, and drying it. It is formed by drying after application and printing using pull-up coating.

The positive electrode active material is not particularly limited as long as it is a material that can reversibly occlude and release alkali metal ions. Typically, an alkali metal-containing transition metal compound can be used as the positive electrode active material. Examples of lithium-containing transition metal compounds include composite oxides containing lithium and at least one element selected from the group consisting of cobalt, manganese, nickel, chromium, iron and vanadium. Examples include lithium-containing transition metal oxides such as lithium cobaltate, lithium nickelate and lithium manganate, olivine-type lithium salts such as _LiFePO4 , chalcogen compounds such as titanium disulfide and molybdenum disulfide, and manganese dioxide. A lithium-containing transition metal oxide is a metal oxide containing lithium and a transition metal or a metal oxide in which a part of the transition metal in the metal oxide is replaced with a different element. Examples of dissimilar elements include Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, B, etc. Among them, Mn, Al, Co, Ni and Mg is preferred. The dissimilar element may be one kind or two or more kinds. These positive electrode active materials can be used alone or in combination of two or more. Nickel hydroxide etc. are mentioned as said active material in a nickel-hydrogen battery.

The negative electrode active material is not particularly limited as long as it is a material that can reversibly occlude and release alkali metal ions. Typically, a carbon material containing graphite having a graphite-type crystal structure can be used as the negative electrode active material. Examples of such carbon materials include natural graphite, spherical or fibrous artificial graphite, non-graphitizable carbon (hard carbon), and easily graphitizable carbon (soft carbon). Materials other than carbon materials include lithium titanate. In addition, from the viewpoint of increasing the energy density of lithium ion batteries, high-capacity materials such as silicon, tin, silicon alloys, tin alloys, silicon oxides, silicon nitrides, and tin oxides can also be suitably used as negative electrode active materials.

As the active material in the nickel-metal hydride battery, the hydrogen storage alloy is exemplified by Zr--Ti--Mn--Fe--Ag--V--Al--W, Ti15Zr21V15Ni29Cr5Co5Fe1Mn8, etc. AB2-based or A2B-based hydrogen storage alloys. .

Positive or negative electrode binders include, for example, PVDF, PTFE, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polyacrylic acid methyl ester, polyacrylic acid ethyl ester, poly Acrylate hexyl ester, polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, Carboxymethyl cellulose and the like can be used. Two types selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene Copolymers of the above materials may also be used. Two or more selected from these may be mixed and used. Examples of the conductive agent contained in the electrode include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, carbon fibers and metal fibers. Conductive fibers such as carbon fluoride, metal powders such as aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, organic conductors such as phenylene derivatives and graphene derivatives material is used.

The active material in a fuel cell is generally a catalyst for a cathode electrode or an anode electrode in which metal fine particles such as platinum, ruthenium or platinum alloy are supported on a catalyst carrier such as carbon. In order to support the catalyst particles on the surface of the catalyst carrier, for example, the catalyst carrier is suspended in water, and a precursor of the catalyst particles is added (chloroplatinic acid, dinitrodiaminoplatinum, platinum(II) chloride, platinum(I) chloride, Bisacetylacetonate platinum, dichlorodiammine platinum, dichlorotetramine platinum, platinum sulfate, ruthenic chloride, iridic acid chloride, rhodium chloride, ferric chloride, cobalt chloride, chromium chloride, gold chloride, silver nitrate, rhodium nitrate, chloride Palladium, nickel nitrate, iron sulfate, copper chloride, and other alloy components are used), dissolved in suspension, alkali is added to generate metal hydroxide, and the catalyst carrier supported on the surface of the catalyst carrier is obtain. By coating such a catalyst carrier on an electrode and reducing it in a hydrogen atmosphere or the like, an electrode having a surface coated with catalyst particles (active material) is obtained.

In the case of solar cells and the like, active materials include tungsten oxide powder, titanium oxide powder, and oxide semiconductor layers such as SnO ₂ , ZnO, ZrO ₂ , Nb ₂ O ₅ , CeO ₂ , SiO ₂ and Al ₂ O ₃ . , a dye is supported on the semiconductor layer. Compounds such as complexes, ruthenium-cis-diaqua-bipyridyl complexes, phthalocyanines and porphyrins, organic-inorganic perovskite crystals can be mentioned.

(Polymerization process unit 20)
As shown in FIG. 1, the polymerization step 20 has a light irradiation device 2a for irradiating light and a polymerization inert gas circulation device 2b for circulating a polymerization inert gas. The light irradiation device 2a irradiates the phase-separated porous film forming layer formed by the printing process unit 10 with light in the presence of a polymerization inert gas to photopolymerize it to form a phase-separated porous film skeleton, thereby forming a porous film precursor. Get body 6.

FIG. 2 is a diagram showing the details of the polymerization process section 20. As shown in FIG. The polymerization inert gas circulating device 2b is formed with a receiving port 2b1 for receiving the transported printing base material 4 and a delivery port 2b2 for delivering the transported printing base material 4. As shown in FIG.

The polymerization process section 20 is equipped with injection nozzles 201 and 202 for injecting an inert polymerization gas (N2) into the inert polymerization gas circulating device 2b. The injection nozzle 201 is arranged to inject the polymerization inert gas from the inside of the polymerization inert gas circulation device 2b toward the receiving port 2b1, and the injection nozzle 202 is arranged to blow the polymerization inert gas from the inside of the polymerization inert gas circulation device 2b toward the delivery port 2b2. arranged to inject a polymerizing inert gas at the bottom. As a result, the inside of the polymerization inert gas circulating device 2b is purged with the polymerization inert gas.

The light irradiation device 2a is appropriately selected according to the absorption wavelength of the photopolymerization initiator contained in the porous film-forming layer, and is not particularly limited as long as it can initiate and progress the polymerization of the compound in the porous film-forming layer. Examples thereof include ultraviolet light sources such as high-pressure mercury lamps, metal halide lamps, hot cathode tubes, cold cathode tubes, and LEDs. However, since light with a shorter wavelength generally tends to reach deeper areas, it is considered necessary to select a light source according to the thickness of the porous film to be formed.

Next, with regard to the irradiation intensity of the light source of the light irradiation device 2a, if the irradiation intensity is too high, the polymerization proceeds rapidly before phase separation occurs sufficiently, which tends to make it difficult to obtain a porous structure. On the other hand, when the irradiation intensity is too weak, phase separation progresses on a microscale or more, and variations in porosity and coarsening tend to occur. In addition, the irradiation time becomes longer, and the productivity tends to decrease. Therefore, the irradiation intensity is preferably 10 mW/cm2 to 1 W/cm2, more preferably 30 mW/cm2 to 300 mW/cm2.

Next, the polymerization inert gas circulating device 2b serves to reduce the concentration of polymerization-active oxygen contained in the atmosphere and to allow the polymerization reaction of the polymerizable compound in the vicinity of the surface of the porous film-forming layer to proceed without hindrance. responsible for Therefore, the polymerization inert gas to be used is not particularly limited as long as it satisfies the above functions, and examples thereof include nitrogen, carbon dioxide and argon.

In addition, considering that the inhibition reduction effect can be effectively obtained as the flow rate, the O2 concentration must be less than 20% (environment with a lower oxygen concentration than the atmosphere), and it is possible to achieve 0 to 15%. and more preferably 0% to 5%.

In addition, the polymerization inert gas circulating device 2b is preferably provided with temperature control means for controlling the temperature in order to realize stable polymerization progress conditions.

(Heating process unit 30)
As shown in FIG. 1, the heating process section 30 has a heating device 3a, and removes the solvent remaining in the porous membrane precursor 6 formed by the polymerization process section 20 by heating and drying it with the heating device 3a. including a solvent removal step. Thereby, a porous layer (porous film) can be formed. The heating process section 30 may perform the solvent removal process under reduced pressure.

In addition, the heating process section 30 heats the porous membrane precursor 6 with the heating device 3a to further accelerate the polymerization reaction performed in the polymerization process section 20, and the porous membrane precursor 6 remains in the polymerization promoting process. It also includes an initiator removing step of removing the photopolymerization initiator by heating and drying it with the heating device 3a. The polymerization acceleration step and the initiator removal step may be performed simultaneously with the solvent removal step, or may be performed before or after the solvent removal step.

Furthermore, the heating process section 30 includes a polymerization completion process of heating the porous membrane under reduced pressure after the solvent removal process. The heating device 3a is not particularly limited as long as it satisfies the above functions, and examples thereof include an IR heater and a hot air heater.

Moreover, the heating temperature and time can be appropriately selected according to the boiling point of the solvent contained in the porous film precursor 6 and the film thickness to be formed.

The porous membrane formed through the above steps contains a resin as a main component. Here, "having a resin as a main component" means that the resin accounts for 50% by mass or more of the total substances constituting the porous membrane. From the viewpoint of ensuring good liquid and gas permeability, the structure of the porous membrane should have a co-continuous structure formed by a continuous cross-linked structure with a three-dimensional branched network structure of a cured resin as a skeleton. is preferred.

In other words, it is preferable that the porous membrane has a large number of pores, and that one of the pores has communication with other surrounding pores and spreads three-dimensionally. When the pores are communicated with each other, liquid and gas can sufficiently permeate, and functions such as substance separation and reaction field can be efficiently exhibited.

The cross-sectional shape of the pores of the porous membrane may be various shapes and sizes such as substantially circular, substantially elliptical, and substantially polygonal. Here, the size of the pores refers to the length of the longest portion in the cross-sectional shape. The size of the pores can be obtained from a cross-sectional photograph taken with a scanning electron microscope (SEM).

The size of pores in the porous membrane is preferably about 0.01 to 10 μm from the viewpoint of liquid and gas permeability.

Moreover, the porosity in the porous membrane is preferably 30 to 90%, more preferably 50 to 90%. If the porosity is lower than the above, there is a tendency that the continuity of the pores is lowered, or the pore diameter becomes as small as several tens of nanometers or less, making it difficult for liquids and gases to permeate. On the other hand, when the porosity is higher than the above range, the three-dimensional network structure of the resin is not sufficiently formed, and the strength of the obtained porous membrane tends to be remarkably lowered.

Next, the porosity of the surface of the porous membrane, that is, the ratio of the total area occupied by surface pores to the surface area is preferably 20% or more, more preferably 50% or more. Also, the average surface pore diameter is preferably 0.01 to 1.0 μm, more preferably 0.1 to 1.0 μm. The ratio and shape of the pores on the surface of the porous membrane have a large effect on the permeation of liquids and gases. trend can be seen.

The thickness of the porous membrane is preferably 0.01 to 500 μm, more preferably 0.01 to 100 μm, like the porous membrane forming layer described above.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Next, Table 1 shows the details of the solvent, printing base material, polymerization process section, and heating process section used to prepare the porous films in Examples and Comparative Examples.

<Example 1>
A phase-separated porous membrane was produced by the following [1] to [5].

[1] Preparation of membrane-forming stock solution As a membrane-forming stock solution for forming a phase-separated porous membrane, the materials were mixed in the following proportions to prepare a membrane-forming stock solution.
・Tricyclodecane dimethanol diacrylate (Daicel Ornix Co., Ltd.): 29 parts by mass ・Methanol (manufactured by Kanto Chemical Industry Co., Ltd.): 70 parts by mass ・Irgacure 184 (manufactured by BASF) (an example of a photoradical generator): 1 mass Part [2] Printing process part:
Next, the printing process unit 10 was used to form a porous film-forming layer. The printer 1a employs an inkjet device. A copper foil having a thickness of 8 μm was used as the printing substrate 4, and the film-forming stock solution prepared above was printed to form a continuous film having a thickness of about 10 μm.

[3] Polymerization step:
In advance, the inside of the polymerization process section 20 was purged with N2 by the polymerization inert gas circulating device 2b to set the O2 concentration inside the polymerization process section 20 to 0%. The inside of the polymerization process section 20 was set to 10° C. by the temperature control mechanism. By transporting the printing base material 4 by the transport unit 5, the porous forming layer formed in [2] is moved into the apparatus of the polymerization process unit 20, and (1) is irradiated with an irradiation intensity of 300 mW/cm for 1 s. and (2) for 10 s at an irradiation intensity of 30 mW/cm 2 , UV irradiation was performed by the light irradiation device 2 a to form a porous precursor.

[4] Heating step (1):
The interior of the heating device 3a is heated in advance to 25° C., and the printing substrate 4 is transported by the transporting unit 5, thereby moving the porous precursor formed in [3] into the heating device 3a, and exposing to the atmosphere. In the inside, the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was accelerated to form a porous membrane (solvent removal step, polymerization acceleration step).

[5] Heating step (2):
Finally, the porous membrane formed in [4] was heated at 120° C. for 20 hours under reduced pressure to treat the remaining initiator and polymerization reaction groups (initiator removal step, polymerization completion step).

As a result of cross-sectional SEM observation, it was found that the porous film obtained in Example 1 had a porosity of 50% or more than the average value near the surface and near the bottom.

FIG. 3 shows the result of surface SEM observation. FIG. 4 shows the result of cross-sectional SEM observation.

The porous membrane obtained in Example 1 was subjected to structural evaluation in the film thickness direction under two conditions. Test and evaluation methods are detailed below. The results are shown in Table 2 below.

Evaluation 1: Film thickness direction structure evaluation 1
In order to evaluate the uniformity of the porous structure of the porous membrane produced by irradiation with an irradiation intensity of 300 mW/cm2 for 1 s, the voids were filled with unsaturated fatty acid, stained with osmium, and then subjected to cross-sectional SEM. The porosity near the surface and near the bottom of the porous membrane was measured. Observation results were evaluated according to the following criteria.

[Evaluation criteria]
○: Difference in porosity near the surface and near the bottom is less than 10% △: Difference in porosity near the surface and near the bottom is 10% or more and less than 15% ×: Difference in porosity near the surface and near the bottom is 20% Evaluation 2: Film thickness direction structure evaluation 2
In order to evaluate the uniformity of the porous structure of the porous membrane produced by irradiation with an irradiation intensity of 30 mW/cm2 for 10 s, the pores were filled with unsaturated fatty acids, stained with osmium, and then subjected to cross-sectional SEM. The porosity near the surface and near the bottom of the porous membrane was measured. Observation results were evaluated according to the following criteria.

[Evaluation criteria]
○: Difference in porosity near the surface and near the bottom is less than 10% △: Difference in porosity near the surface and near the bottom is 10% or more and less than 15% ×: Difference in porosity near the surface and near the bottom is 20% Above Next, the porous film obtained in Example 1 was evaluated for curing shrinkage. Test and evaluation methods are detailed below. The results are shown in Table 2 below.

Evaluation 3: Evaluation of Curing Shrinkage Rate Before and after the solvent removal process and the polymerization promotion process of the prepared porous film, the degree of cure shrinkage was measured by warping of the substrate and evaluated according to the following criteria.

[Evaluation criteria]
○: difference in cure shrinkage rate before and after solvent removal step and polymerization promotion step is less than 10% ×: difference in cure shrinkage rate before and after solvent removal step and polymerization promotion step is 10% or more <Comparative Example 1>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 1, except that the inside of the polymerization inert gas circulating device 2b was set at 25° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 1 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 1 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Example 2>
A phase-separated porous membrane was produced as follows.

In the heating process section (1), the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was accelerated in an atmosphere of 0% O concentration to form a porous membrane. ] to [5], a phase-separated porous membrane was produced.

As a result of cross-sectional SEM observation of the porous film obtained in Example 2, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

In the same manner as in Example 1, film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation were performed on the porous film of Example 2 above. Results are shown in Table 2.

<Example 3>
A phase-separated porous membrane was produced by the following [1] to [5].

[1] Preparation of membrane-forming stock solution As a membrane-forming stock solution for forming a phase-separated porous membrane, the materials were mixed in the following proportions to prepare a membrane-forming stock solution.
・Tricyclodecane dimethanol diacrylate (Daicel Ornix Co., Ltd.): 29 parts by mass ・Ethanol (manufactured by Kanto Chemical Industry Co., Ltd.): 70 parts by mass ・Irgacure 184 (manufactured by BASF) (an example of a photoradical generator): 1 mass Part [2] Printing process part:
Next, the printing process unit 10 was used to form a porous film-forming layer. The printer 1a employs an inkjet device. A copper foil having a thickness of 8 μm was used as the printing substrate 4, and the film-forming stock solution prepared above was printed to form a continuous film having a thickness of about 10 μm.

[3] Polymerization step:
In advance, the inside of the polymerization process section 20 was purged with N2 by the polymerization inert gas circulating device 2b to set the O2 concentration inside the polymerization process section 20 to 0%. The inside of the polymerization process section 20 was set to 10° C. by the temperature control mechanism. By transporting the printing base material 4 by the transport unit 5, the porous forming layer formed in [2] is moved into the apparatus of the polymerization process unit 20, and (1) is irradiated with an irradiation intensity of 300 mW/cm for 1 s. and (2) for 10 s at an irradiation intensity of 30 mW/cm 2 , UV irradiation was performed by the light irradiation device 2 a to form a porous precursor.

[4] Heating step (1):
The interior of the heating device 3a is heated in advance to 25° C., and the printing substrate 4 is transported by the transporting unit 5, thereby moving the porous precursor formed in [3] into the heating device 3a, and exposing to the atmosphere. In the inside, the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was accelerated to form a porous membrane (solvent removal step, polymerization acceleration step).

[5] Heating step (2):
Finally, the porous membrane formed in [4] was heated at 120° C. for 20 hours under reduced pressure to treat the remaining initiator and polymerization reaction groups (initiator removal step, polymerization completion step).

As a result of cross-sectional SEM observation, it was found that the porous membrane obtained in Example 3 had a porosity of 50% or more than the average value of the vicinity of the surface and the vicinity of the bottom.

In the same manner as in Example 1, the porous film obtained in Example 3 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and curing shrinkage evaluation. The results are shown in Table 2 below.

<Comparative Example 2>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 3, except that the inside of the polymerization inert gas circulating device 2b was set at 25° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 2 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 2 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Example 4>
A phase-separated porous membrane was produced as follows.

In the heating process section (1), the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was promoted in an atmosphere of 0% O concentration to form a porous membrane. ] to [5], a phase-separated porous membrane was produced.

As a result of cross-sectional SEM observation of the porous film obtained in Example 4, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

In the same manner as in Example 1, the porous film of Example 4 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and cure shrinkage evaluation. Results are shown in Table 2.

<Example 5>
A phase-separated porous membrane was produced by the following [1] to [5].

[1] Preparation of membrane-forming stock solution As a membrane-forming stock solution for forming a phase-separated porous membrane, the materials were mixed in the following proportions to prepare a membrane-forming stock solution.
・ Tricyclodecane dimethanol diacrylate (Daicel Ornix Co., Ltd.): 29 parts by mass ・ NN dimethylacetamide (manufactured by Tokyo Kasei Co., Ltd.): 70 parts by mass ・ Irgacure 184 (manufactured by BASF) (an example of a photoradical generator): 1 Mass part [2] Printing process part:
Next, the printing process unit 10 was used to form a porous film-forming layer. The printer 1a employs an inkjet device. A copper foil having a thickness of 8 μm was used as the printing substrate 4, and the film-forming stock solution prepared above was printed to form a continuous film having a thickness of about 10 μm.

[3] Polymerization step:
In advance, the inside of the polymerization process section 20 was purged with N2 by the polymerization inert gas circulating device 2b to set the O2 concentration inside the polymerization process section 20 to 0%. The inside of the polymerization process section 20 was set to 10° C. by the temperature control mechanism. By transporting the printing base material 4 by the transport unit 5, the porous forming layer formed in [2] is moved into the apparatus of the polymerization process unit 20, and (1) is irradiated with an irradiation intensity of 300 mW/cm for 1 s. and ( ) for 10 s at an irradiation intensity of 30 mW/cm 2 , UV irradiation was performed by the light irradiation device 2 a to form a porous precursor.

[4] Heating step (1):
The inside of the heating device 3a is heated in advance to 50° C., and the printing base material 4 is transported by the transporting unit 5, thereby moving the porous precursor formed in [3] into the heating device 3a and exposing it to the atmosphere. In the inside, the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was accelerated to form a porous membrane (solvent removal step, polymerization acceleration step).

[5] Heating step (2):
Finally, the porous membrane formed in [4] was heated at 120° C. for 20 hours under reduced pressure to treat the remaining initiator and polymerization reaction groups (initiator removal step, polymerization completion step).

As a result of cross-sectional SEM observation, it was found that the porous film obtained in Example 5 had a porosity of 50% or more than the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film obtained in Example 5 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and cure shrinkage evaluation. The results are shown in Table 2 below.

<Example 6>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 5, except that the inside of the polymerization inert gas circulation device 2b was set at 25° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation of the porous film obtained in Example 6, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

FIG. 5 shows the result of surface SEM observation. FIG. 6 shows the result of cross-sectional SEM observation.

In the same manner as in Example 1, film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation were performed on the porous film of Example 6 above. Results are shown in Table 2.

<Comparative Example 3>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 5, except that the inside of the polymerization inert gas circulating device 2b was set at 50° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 3 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 3 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Comparative Example 4>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 5, except that the inside of the polymerization inert gas circulating device 2b was set at 80° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 4 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 4 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and cure shrinkage evaluation. Results are shown in Table 2.

<Example 7>
A phase-separated porous membrane was produced by the following [1] to [5].

[1] Preparation of membrane-forming stock solution As a membrane-forming stock solution for forming a phase-separated porous membrane, the materials were mixed in the following proportions to prepare a membrane-forming stock solution.
・Tricyclodecane dimethanol diacrylate (Daicel Ornix Co., Ltd.): 29 parts by mass ・Tetradecane (manufactured by Tokyo Kasei Co., Ltd.): 70 parts by mass ・Irgacure 184 (manufactured by BASF) (an example of a photoradical generator): 1 part by mass [2] Printing process department:
Next, the printing process unit 10 was used to form a porous film-forming layer. The printer 1a employs an inkjet device. A copper foil having a thickness of 8 μm was used as the printing substrate 4, and the film-forming stock solution prepared above was printed to form a continuous film having a thickness of about 10 μm.

[3] Polymerization step:
In advance, the inside of the polymerization process section 20 was purged with N2 by the polymerization inert gas circulating device 2b to set the O2 concentration inside the polymerization process section 20 to 0%. The inside of the polymerization process section 20 was set to 10° C. by the temperature control mechanism. By transporting the printing base material 4 by the transport unit 5, the porous forming layer formed in [2] is moved into the apparatus of the polymerization process unit 20, and (1) is irradiated with an irradiation intensity of 300 mW/cm for 1 s. and (2) for 10 s at an irradiation intensity of 30 mW/cm 2 , UV irradiation was performed by the light irradiation device 2 a to form a porous precursor.

[4] Heating step (1):
The inside of the heating device 3a is heated in advance to 80° C., and the printing base material 4 is transported by the transporting unit 5, thereby moving the porous precursor formed in [3] into the heating device 3a and exposing it to the atmosphere. In the inside, the solvent remaining in the porous membrane precursor was removed and the polymerization reaction was accelerated to form a porous membrane (solvent removal step, polymerization acceleration step).

[5] Heating step (2):
Finally, the porous membrane formed in [4] was heated at 120° C. for 20 hours under reduced pressure to treat the remaining initiator and polymerization reaction groups (initiator removal step, polymerization completion step).

As a result of cross-sectional SEM observation, it was found that the porous film obtained in Example 7 had a porosity of 50% or more than the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film obtained in Example 7 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and cure shrinkage evaluation. The results are shown in Table 2 below.

<Example 8>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 7, except that the inside of the polymerization inert gas circulation device 2b was set at 25° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation of the porous film obtained in Example 8, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

In the same manner as in Example 1, film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation were performed on the porous film of Example 8 above. Results are shown in Table 2.

<Example 9>
A phase-separated porous membrane was produced as follows.

[0] Formation of Negative Electrode Active Material Layer 97 parts by mass of graphite particles (average particle size 10 μm) as the negative electrode active material, 1 part by mass of cellulose as a thickening agent, and 2 parts by mass of an acrylic resin as a binder were uniformly dispersed in water. Dispersed to obtain a negative electrode active material dispersion. This dispersion is applied to a copper foil having a thickness of 8 μm, which is a negative electrode substrate, and the resulting coating film is dried at 120° C. for 10 minutes and pressed to form a negative electrode active material, which is a porous substrate having a thickness of 60 μm. got a layer. Finally, a piece of 50 mm×33 mm was cut out to obtain a negative electrode.

[1] Preparation of membrane-forming stock solution As a membrane-forming stock solution for forming a phase-separated porous membrane, the materials were mixed in the following proportions to prepare a membrane-forming stock solution.
・Tricyclodecane dimethanol diacrylate (Daicel Ornix Co., Ltd.): 29 parts by mass ・Tetradecane (manufactured by Kanto Chemical Industry Co., Ltd.): 70 parts by mass ・Irgacure 184 (manufactured by BASF): 1 part by mass [2] Printing process:
Next, a porous film-forming layer was formed using the printing process section 101a. An inkjet device was adopted as the printing device. The copper foil formed with the negative electrode active material layer prepared in [1] was used as the printing substrate 4, and the film forming stock solution prepared above was printed to form a continuous film having a thickness of about 10 μm.

After the printing process, a phase-separated porous membrane was produced in the same manner as [3] to [5] described in Example 8. That is, an electrode including a battery electrode active material layer containing an active material and a porous layer formed on the battery electrode active material layer was produced.

As a result of cross-sectional SEM observation of the porous film obtained in Example 9, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

In the same manner as in Example 1, the porous film of Example 9 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Example 10>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 7, except that the inside of the polymerization inert gas circulating device 2b was set at 50° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation of the porous film obtained in Example 10, it was found that a porous film having a porosity of 50% or more than the average value near the surface and near the bottom was formed.

In the same manner as in Example 1, the porous film of Example 10 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Comparative Example 5>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 7, except that the inside of the polymerization inert gas circulating device 2b was set at 80° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 5 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 5 was subjected to film thickness direction structural evaluation 1, film thickness direction structural evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

<Comparative Example 6>
A phase-separated porous membrane was produced as follows.

A phase-separated porous membrane was produced in the same manner as [1] to [5] described in Example 7, except that the inside of the polymerization inert gas circulation device 2b was set at 120° C. in the polymerization process section 20.

As a result of cross-sectional SEM observation, the porous film obtained in Comparative Example 6 was found to have a porosity of 30% or more and less than 50% of the average value near the surface and near the bottom.

In the same manner as in Example 1, the porous film of Comparative Example 6 was subjected to film thickness direction structure evaluation 1, film thickness direction structure evaluation 2, and curing shrinkage evaluation. Results are shown in Table 2.

From the results of evaluation 1 and evaluation 2 in Table 2, it was found that porous films having a porous structure with small variation in the film thickness direction were obtained in Examples 1 to 10.

Among them, in Example 9, the battery electrode active material layer, which is a porous base material, was used as the printed base material, but the ideal variation was small as in the other examples using copper foil as the printed base material. A porous structure is obtained.

Also, in Example 10, the temperature during polymerization was set at 50° C., but as far as the evaluation results are concerned, an ideal porous film was obtained.

Tetradecane used as a solvent has a relatively high boiling point of 253.degree.

Therefore, even when the temperature during polymerization is set to 50° C., the solvent does not dry out, so the polymerization proceeded while the monomer concentration was kept constant before and during the polymerization.

On the other hand, in the manufacturing process environment such as Comparative Examples 1 to 6, where the solvent is easily dried, a gradient of the monomer concentration occurs before and during the polymerization, and it is considered difficult to obtain a porous structure with small variations in the film thickness direction.

Therefore, it is important to devise a manufacturing process that does not dry the solvent before the solvent removal process, and it is important to form a porous film with small variations. It can be seen that a porous structure with small variations in the film thickness direction can be obtained by suppressing the thickness to .

Finally, with regard to Examples 2 and 4, the results show that the distortion of the resulting porous membrane is increased by drying and accelerating the polymerization without exposing the membrane to the atmosphere after polymerization. The drying and polymerization promotion step corresponds to the step of advancing the reaction of the polymerizable reactive groups remaining after the formation of the porous skeleton. It is thought that the reaction rate of the reactive groups is high, and distortion is likely to occur compared to the treatment conditions in atmospheric treatment.

In the conventional method for producing a phase-separated porous membrane using a polymerization reaction, the porous formation time is long, the productivity is not sufficient, and the permeability varies with the production method in which heat is used as a trigger. In addition, in the manufacturing method using light, the porous formation time is short and the productivity is high, but the permeability is not sufficient. However, from the above results, in the present embodiment, excellent permeability can be ensured in the porous layer (membrane) produced by phase separation using a polymerization reaction.

As described above, the method for producing a porous layer according to one embodiment of the present invention includes a preparation step of preparing a porous forming layer comprising a polymerizable compound, a polymerization initiator, and a solvent on a substrate; A polymerization step of activating an agent to polymerize a polymerizable compound to form a porous skeleton, and a solvent removal step of removing a solvent contained in the porous forming layer to obtain a porous layer, wherein the polymerization step comprises , at a temperature lower than that in the solvent removal step.

Since the porous skeleton is formed by the polymerization of the polymerizable compound, a porous layer having a three-dimensional network structure with excellent heat resistance can be obtained. In addition, drying of the solvent is suppressed in the polymerization step as compared with the solvent removal step, so variation in concentration of the polymerizable compound is suppressed, and variation in porosity in the film thickness direction is reduced. Therefore, a porous layer having a large porosity and excellent permeability can be obtained. Preferably, the temperature in the polymerization step is below the boiling point of the solvent.

The solvent removal step includes heat treatment. Thereby, the solvent contained in the porous forming layer can be removed by drying.

In the preparation step, the polymerizable compound is contained in the porous-forming layer at 10-50 wt %. Thereby, the porous layer can be reliably formed and the permeability can be ensured.

The polymerization initiator includes a photopolymerization initiator, and in the polymerization step, the photopolymerization initiator is activated by irradiating the porous forming layer with light. As a result, the degree of freedom in setting the temperature in the polymerization process is improved compared to when a thermal polymerization initiator is mainly used as the polymerization initiator.

The polymerization initiator contains a radical generator, and the polymerization process is carried out in an environment with a lower oxygen concentration than the atmosphere.

As a result, the radical generator is activated and the polymerizable compound is polymerized to form a porous skeleton, so that a porous layer having a three-dimensional network structure with excellent heat resistance can be reliably obtained in a short time. . In addition, since the polymerization process is performed in an environment where the oxygen concentration is lower than that of the atmosphere, it is possible to reduce the local polymerization inhibition of the polymerizable compound by reducing the variation in the radical concentration caused by the local variation in the oxygen concentration. can be done. Therefore, the total area occupied by the pores on the surface of the porous layer can be increased, and a porous layer with excellent permeability can be obtained.

After the polymerization step, a heating step of heating the porous skeleton in the atmosphere is provided. As a result, it is possible to promote the polymerization of the polymerizable compound and remove the polymerization initiator while suppressing curing shrinkage, thereby obtaining a porous layer having a large total area occupied by pores on the surface of the porous layer and excellent production efficiency. be able to.

A step of heating the porous layer under reduced pressure is included after the solvent removal step. Thereby, the polymerization of the polymerizable compound can be completed, and a high-quality porous layer with excellent long-term stability can be obtained.

The substrate is a porous substrate, and the porous layer is a porous membrane having a co-continuous structure. This makes it possible to obtain a porous structure in which the functionality of the porous film is imparted to the porous base material.

The porous substrate is a battery electrode active material layer containing an active material. Thereby, it is possible to obtain a battery electrode in which functionality is imparted by the porous film to the active material substrate.

A porous layer according to an embodiment of the present invention is a porous layer formed by a continuous crosslinked structure, and the difference between the porosity of the cross section near the surface and the porosity of the cross section near the bottom is less than 10%. Thereby, it is possible to obtain a porous layer which is excellent in heat resistance due to the continuous crosslinked structure, has a small variation in porosity in the film thickness direction, and is excellent in permeability.

Since the pores are connected to other surrounding pores and have communication properties, the permeation of liquid or gas occurs sufficiently, and the functions such as substance separation and reaction field can be efficiently exhibited.

When the thickness is 0.1 to 500 μm, it is possible to obtain a porous structure with small variations in the film thickness direction while sufficiently obtaining the function of forming the porous film.

When the porosity of the entire layer is 30 to 90%, it is possible to secure the strength of the porous membrane while securing the permeability.

Permeability can be ensured when the average pore size of the surface pores is 0.01 to 1.0 μm.

An electrode according to one embodiment of the present invention includes a battery electrode active material layer containing an active material, and the porous layer formed on the battery electrode active material layer. Thereby, it is possible to obtain a battery electrode in which functionality is imparted by the porous film to the active material substrate.

1a: Printing device 1b: Ink container 1c: Ink supply tube 2a: Light irradiation device 2b: Polymerization inert gas flow device 3a: Heating device 4: Printing substrate 5: Conveying unit 6: Porous film precursor 7: Film forming Stock solution 10: printing process section 20: polymerization process section 30: heating process section

… Japanese Patent Publication No. 62-19294 … JP 2004-41835 …Patent No. 5153142 …Patent No. 3168006 …Patent No. 6142118 … Special table 2009-502583

Claims (13)

a preparation step of preparing a porous forming layer containing a polymerizable compound, a polymerization initiator and a solvent on a substrate;
a polymerization step of activating the polymerization initiator of the porous forming layer to polymerize the polymerizable compound to form a porous skeleton;
a solvent removing step of removing the solvent contained in the porous forming layer to obtain a porous layer;
with
The base material is a porous base material,
The porous layer is a porous membrane having a co-continuous structure,
A method for producing a porous layer, wherein the polymerization step is performed at a temperature lower than the temperature in the solvent removal step. 2. The method for producing a porous layer according to claim 1, wherein in said solvent removing step, said porous forming layer is heated. 3. The method for producing a porous layer according to claim 1, wherein in said preparation step, said polymerizable compound is contained in said porous forming layer in an amount of 10 to 50 wt %. The polymerization initiator includes a photopolymerization initiator,
4. The method for producing a porous layer according to claim 1, wherein in the polymerization step, the photopolymerization initiator is activated by irradiating the porous forming layer with light. The polymerization initiator contains a radical generator,
5. The method for producing a porous layer according to any one of claims 1 to 4, wherein the polymerization step is performed in an environment having an oxygen concentration lower than that of the atmosphere. 6. The method for producing a porous layer according to claim 1, further comprising a heating step of heating the porous skeleton in the atmosphere after the polymerization step. 7. The method for producing a porous layer according to claim 1, further comprising a step of heating the porous layer under reduced pressure after the step of removing the solvent. 8. The method for producing a porous layer according to claim 1 , wherein the porous substrate is a battery electrode active material layer containing an active material. a battery electrode active material layer containing an active material;
a porous layer formed on the battery electrode active material layer;
The electrode , wherein the porous layer is a porous layer formed by a continuous crosslinked structure, and the difference between the porosity of the cross section near the surface and the porosity of the cross section near the bottom is less than 10%. 10. The electrode according to claim 9 , wherein the pores of said porous layer are interconnected with other surrounding pores. 11. The electrode according to claim 9 , wherein the porous layer has a thickness of 0.1 to 500 μm. The electrode according to any one of claims 9 to 11 , wherein the porosity of the entire porous layer is 30 to 90%. The electrode according to any one of claims 9 to 12 , wherein the pores on the surface of the porous layer have an average pore size of 0.01 to 1.0 µm.

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