JP7728161B2 - Photocurable resin composition, method for producing the same, and method for producing a photocured product - Google Patents

Description

Embodiments of the present invention relate to a photocurable resin composition, a method for producing the same, and a method for producing a photocured product.

A type of stereolithography technology is known that creates three-dimensional objects by irradiating light onto a slurry made by mixing solid powders such as metal or ceramic particles with a liquid photocurable resin to harden it. In one typical configuration of this type of stereolithography technology, for example, slurry is ejected from a syringe and deposited, smoothed and leveled with a squeegee, and light is irradiated onto a predetermined area of the smoothed slurry deposit to form a hardened layer. Further, slurry is supplied onto the hardened layer and smoothed and leveled with a squeegee, and light is irradiated onto a predetermined area of the smoothed slurry deposit to form another hardened layer. Similar operations are then repeated to ultimately create a three-dimensional additively manufactured object, which is an assembly of multiple hardened layers.

For example, in solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), efforts are being made to make them more compact by making electrodes such as the oxygen and hydrogen electrodes porous and creating an electrode-channel integrated structure in which the electrodes also function as gas channels. Lanthanum strontium cobalt iron oxide (LSCF) particles are used as the constituent material for the oxygen electrodes of such SOFCs and SOECs. When electrodes using LSCF particles are fabricated using conventional ceramic manufacturing techniques, the lamination and compression bonding method is used. While this method has the advantages of enabling mass production and firing of an integrated structure, it has been difficult to form microstructures.

When applying stereolithography to the manufacture of electrodes using LSCF particles, a mixed slurry of photocurable resin and LSCF particles is used. The aforementioned steps of discharging and depositing the slurry, smoothing the slurry deposit with a squeegee, and irradiating the slurry deposit with light are repeated multiple times to create a three-dimensional additively molded object, which is then fired to produce a porous electrode. Stereolithography has the advantage of easily forming fine structures. However, because LSCF particles are black, when they are mixed with photocurable resin and stereolithography is performed, the light from the light source is absorbed by the black particles, preventing the light from reaching a certain depth. This presents a drawback: the entire object cannot be photocured uniformly. This drawback is not limited to the use of LSCF particles; it also arises when, for example, conductive particles such as carbon and photocurable resin are used to manufacture conductive components using stereolithography.

Japanese Patent Application Laid-Open No. 2006-257323 Japanese Patent Application Laid-Open No. 2019-064861 Japanese Patent Application Publication No. 7-289873

The problem that the present invention aims to solve is to provide a photocurable resin composition that can be photocured satisfactorily even when black inorganic particles are blended, a method for producing the same, and a method for producing a photocured product.

a step of forming a first photocured product of the photocurable resin composition by irradiating a desired region of the molded product of the slurry of the photocurable resin composition with light; a step of molding the slurry of the photocurable resin composition on the first photocured product of the photocurable resin composition; and a step of forming a second photocured product on the first photocured product of the photocurable resin composition by irradiating a desired region of the molded product of the slurry of the photocurable resin composition with light;

FIG. 2 is a cross-sectional view schematically illustrating a first example of a filler particle in the photocurable resin composition according to the embodiment. FIG. 3 is a cross-sectional view schematically showing a second example of a filler particle in the photocurable resin composition according to the embodiment. 1A to 1C are cross-sectional views illustrating a method for producing a photocured product according to an embodiment. FIG. 1 is a cross-sectional view showing an electrochemical cell produced according to an example.

The photocurable resin composition of the present invention, its manufacturing method, and its manufacturing method for a photocured product according to the present invention will be described below with reference to the drawings. In each of the following embodiments, substantially identical components are designated by the same reference numerals, and some of their descriptions may be omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each component, etc. may differ from the actual values. In the following description, the symbol "to" indicates a range between the respective upper and lower limit values. In such cases, each range includes both the upper and lower limit values.

(Photocurable resin composition and method for producing the same)
A photocurable resin composition according to an embodiment includes a matrix resin that is cured by irradiation with light and filler particles that are dispersed in the matrix resin and contain black inorganic particles. In the photocurable resin composition according to an embodiment, the filler particles include black inorganic particles and a white inorganic substance that is provided so as to cover the surfaces of the black inorganic particles. The photocurable resin composition according to the embodiment and a method for producing the same are described in detail below.

Matrix resins that harden when exposed to light (photocurable resins) are resins that harden (photocure) by increasing the molecular weight through chain polymerization of monomers using light. Photocuring refers to changing from a liquid to a solid through the action of light energy, and organic materials that harden are called photocurable resins. Ultraviolet light is generally used as the light that provides the hardening effect. Ultraviolet lasers are useful because they have a high energy density and can be focused to a small spot diameter. However, resins that harden with visible light are also widely used industrially.

Liquid photocurable resin cures in roughly the following steps: The photopolymerization initiator absorbs ultraviolet light, and after absorbing the ultraviolet light, the photopolymerization initiator becomes activated. The activated photopolymerization initiator then undergoes decomposition and reacts with resin components such as monomers and oligomers. These reaction products then react with resin components, and the reaction progresses in a chain reaction. Then, a three-dimensional crosslinking reaction progresses, increasing the molecular weight, and the resin hardens into a solid.

Photocurable resins are generally composed of monomers, oligomers, photopolymerization initiators, and various additives (stabilizers, fillers, pigments, etc.). Polymerization methods can be broadly divided into cationic polymerization and radical polymerization.

Monomers are molecules with functional groups that become the repeating units of resins that harden when exposed to light. They become polymers when polymerized by light. Examples of monomers that undergo cationic polymerization include vinyl ether monomers. Examples of monomers that undergo radical polymerization include acrylate monomers and phthalate monomers. The names vinyl ether monomer, phthalate monomer, and acrylate monomer are general terms for compounds, and include all those to which various functional groups are attached.

Oligomers are formed by reacting several monomers in advance, and like monomers, they polymerize under light to form polymers. Examples of oligomers that undergo cation polymerization include vinyl ether oligomers, alicyclic photocurable oligomers, and glycidyl ether photocurable oligomers. Examples of oligomers that undergo radical polymerization include urethane acrylate oligomers, polyester acrylate oligomers, photocurable acrylate oligomers, and acrylic acrylate oligomers. The names vinyl ether oligomers, alicyclic photocurable oligomers, glycidyl ether photocurable oligomers, urethane acrylate oligomers, polyester acrylate oligomers, photocurable acrylate oligomers, and acrylic acrylate oligomers are general terms for compounds, and include all of these with various functional groups attached.

In the photocurable resin of the embodiment, the resin component as the main component may be only a monomer or only an oligomer, or may be a mixture of both in any ratio.

Photopolymerization initiators are components that absorb light and become activated (excited), causing reactions such as cleavage reactions, hydrogen (proton) abstraction reactions, and electron transfer reactions. These reactions generate reaction initiators, such as radical molecules in the case of acrylic photocurable resins and hydrogen ions in the case of photocurable resins. The generated radical molecules and hydrogen ions attack monomer molecules and oligomers, causing three-dimensional polymerization and crosslinking reactions, which leads to curing. When this reaction results in molecules of a certain size or larger, the irradiated portion changes from a liquid state to a solid state. Photopolymerization initiators used in cationic polymerization include sulfonium and iodonium. Photopolymerization initiators used in radical polymerization include benzophenone, acetophenone, and thioxanthone. The names sulfonium, iodonium, benzophenone, acetophenone, and thioxanthone are general terms for these compounds and include all of these with various functional groups attached.

To improve the spreadability (workability) of the photopolymerization initiator during squeegeeing, a diluent solvent for the photocurable resin (matrix resin) may be added to adjust the viscosity. Examples of diluents for photocurable resins include Aronix (a low-viscosity photocurable resin product manufactured by Toagosei Co., Ltd.). Among Aronix products, suitable diluents for photocurable resins include M-101A (phenol EO (ethylene oxide)-modified acrylate), M-117 (nonylphenol EO (ethylene oxide)-modified acrylate), M-220 (polypropylene glycol diacrylate), M-309 (trimethylolpropane acrylate), and M-350 (trimethylolpropane EO (ethylene oxide)-modified acrylate). To improve the workability described above, the dilution solvent for the photocurable resin is preferably added in an amount of 50% by mass or less, and more preferably in the range of 5 to 50% by mass, based on the total mass of the photocurable resin excluding the dilution solvent in the embodiment.

An antifoaming agent may be added to the photocurable resin (matrix resin) to prevent foaming or to eliminate foam that has formed. The antifoaming agent is not particularly limited, but a dimethyl silicone antifoaming agent (such as TSA720 (trade name, manufactured by Momentive Performance Materials Japan, LLC)) can be used. However, this is not limiting. Furthermore, the photocurable resin of the embodiment may contain additives other than the above-mentioned antifoaming agents.

Furthermore, a photopolymerization inhibitor may be added to improve the storage stability of the photocurable resin. Examples of photopolymerization inhibitors that can be used include nitrosamine-based polymerization inhibitors. Examples of photopolymerization inhibitors that can be used include Q-1300 and Q-1301 (trade names, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Furthermore, a thermal polymerization initiator may be used to adjust the curing speed of the photocurable resin. Examples of azo thermal polymerization initiators that can be used include AIBN, V-40, V-59, V-65, V-70, and V-601 (trade names, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

The filler particles dispersed in the photocurable resin described above comprise black inorganic particles and a white inorganic substance provided so as to coat the surfaces of the black inorganic particles. The filler particles are appropriately selected depending on the intended use of the photocured product (stereolithography product) produced using the photocurable resin composition of the embodiment. For example, when the photocurable resin composition is used as an oxygen electrode material for an electrochemical cell such as an SOFC or SOEC, LSCF particles can be used as the black inorganic particles. LSCF particles have a composition of (La1 _{- xSrx} )(Co1 _{-yFey ) O3-δ} (0<x<1, 0<y<1, 0<δ<1). When the photocured product of the photocurable resin composition is used as a conductive member, examples of the black inorganic particles include carbon particles such as carbon, graphene, carbon nanotubes, fullerenes, and ketjen black, and metal particles such as iron particles. In addition to these, various black inorganic particles can be used depending on the intended use, such as manganese particles and boron carbide particles. The black inorganic particles may be one type of particle or a mixture of two or more types of particles.

Furthermore, the white inorganic material coated on the surface of the black inorganic particles may be a film-like material or a particulate material suitable for coating, and can be appropriately selected depending on the coating method to be used. For example, when adhesive coating or powder plating is used as the coating method for the white inorganic material, white inorganic particles are used. Examples of white inorganic particles include ceria particles, gadolinium-doped ceria particles, aluminum oxide particles, zirconium oxide particles, aluminum nitride particles, and barium titanate particles. These particles are appropriately selected depending on the application of the photocured product (stereolithography product) produced using the photocurable resin composition of the embodiment. For example, when the photocurable resin composition is used as an oxygen electrode material for electrochemical cells such as SOFCs and SOECs, gadolinium-doped ceria particles, which are used as part of the constituent materials for oxygen electrodes, are suitable as the white inorganic particles. White inorganic particles other than gadolinium-doped ceria particles can also be used depending on the application.

The white inorganic substances, such as black inorganic particles and white inorganic particles, used in the embodiments may be those that have relatively different light absorption capabilities. White inorganic particles may be those that absorb less light than black inorganic particles and are more likely to reflect light. Black inorganic particles are, for example, particles with a color tone ranging from black to dark gray that are more likely to absorb light, and have an average light reflectance (reflectance when irradiated with light having a wavelength of 350 to 750 nm) of 10% or less. On the other hand, white inorganic particles are, for example, particles with a color tone ranging from white to light gray that are more likely to reflect light, and have an average light reflectance (reflectance when irradiated with light having a wavelength of 350 to 750 nm) of 40% or more. The reflectance can be measured using a colorimeter (Konica Minolta, CM-5) or the like.

The black inorganic particles preferably have an average particle size of, for example, approximately 0.8 to 10 μm. The average particle size of the black inorganic particles may be the primary particle size or the secondary particle size of aggregates or granules. If the average particle size of the black inorganic particles is less than 0.8 μm, it is difficult to coat their surfaces with white inorganic particles. If the average particle size of the black inorganic particles exceeds 10 μm, their function as a filler dispersed in the photocurable resin is likely to be reduced. The white inorganic particles preferably have an average particle size of, for example, approximately 0.1 to 0.5 μm. If the average particle size of the white inorganic particles is less than 0.1 μm or more than 0.5 μm, the uniform adhesion of the black inorganic particles to the surface is likely to be reduced. The particle size distribution of the inorganic particles is not particularly limited. Here, the average particle size is defined by the median diameter (D50), and the particle size distribution is defined by the volume distribution and number distribution. The average particle size can be measured using a laser diffraction/scattering particle size distribution analyzer (HORIBA, LA-960V2) or similar. Furthermore, the above-described effects can be achieved even when white particles adhere to and cover aggregates of black particles.

The surfaces of the black inorganic particles and white inorganic particles may be subjected to a surface treatment such as silane coupling treatment to improve dispersibility. Silane coupling treatment can improve wettability with the photocurable resin. Examples of silane coupling agents used in the silane coupling treatment include epoxy silane, amino silane, vinyl silane, methacryl silane, mercapto silane, methoxy silane, and ethoxy silane. Surface modification treatment with these silane coupling agents can also achieve the same effect if added later.

The surfaces of black and white inorganic particles can also be treated with titanate coupling agents to improve wettability with photocurable resins. Examples of titanate coupling agents used in titanate coupling treatment include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, tetraisopropyl bis(dioctylphosphite) titanate, tetraoctyl bis(ditridecylphosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, and bis(dioctylpyrophosphate)oxyacetate titanate. Surface modification treatments using these titanate coupling agents can also achieve similar effects when added later.

Methods for coating the surfaces of black inorganic particles with white inorganic particles include coating with an adhesive or powder plating. When coating with an adhesive, examples of suitable adhesives include thermoplastic resins such as sodium silicate, vinyl acetate resin, polyvinyl resin, ethylene vinyl acetate resin, vinyl chloride resin, acrylic resin, polyamide resin, cellulose, polyvinylpyrrolidone, polystyrene resin, cyanoacrylate, and polyvinyl acetal, as well as thermosetting resins such as epoxy resin, urethane resin, polyaromatic, structural acrylic resin, urea resin, melamine resin, phenolic resin, and resorcinol resin. For example, as shown in Figure 1, adhesive 2 is applied to the surface of black inorganic particles or agglomerated particles 1 formed by aggregating black inorganic particles to a certain size using a spray or other method. White inorganic particles 3 are then attached before adhesive 2 hardens, and adhesive 2 is then fully hardened. In this manner, filled particles 4 are obtained, in which the surfaces of black inorganic particles 1 are coated with white inorganic particles 3.

Next, we will describe a method of using powder plating to coat the surface of black inorganic particles with white inorganic particles. Powder plating is a technique for plating a powder (here, white inorganic particles) onto the surface of a base material (here, black inorganic particles), or a technique for plating a material (here, white inorganic particles) on the surface of a powder (here, black inorganic particles). First, we will describe the case where black inorganic particles are used as the substrate and Ag plating is used as the metal plating material. There are no particular limitations on the plating method, and electroplating, electroless plating, or displacement plating can be used.

Electroplating requires an electroplating bath. Components of electroplating baths include metal salts, conductivity salts, anode dissolution accelerators, complexing agents, and additives that adjust the appearance and physical properties of the film. Components of electroless plating baths include metal salts as well as reducing agents, complexing agents, pH buffers, and stabilizers. Substitution plating uses a plating bath in which complexing agents and additives are added to metal salts.

For example, while the majority of silver plating baths are alkaline silver cyanide plating baths, non-cyanide baths can also be used. A typical metal salt is one whose main ingredient is potassium silver cyanide. This is a complex salt of silver ions. It is a colorless, transparent crystal that dissolves well in water. In addition to this compound, a silver cyanide plating bath also contains free potassium cyanide or sodium cyanide, potassium carbonate, potassium hydroxide, brighteners, hardeners, etc. Black inorganic particles and white inorganic particles are dispersed in a plating bath composed of silver ions, and the surfaces of the black inorganic particles 1 are coated with white inorganic particles 3 via a plating film 5, as shown in Figure 2. In this way, filled particles 4 are obtained, in which the surfaces of the black inorganic particles 1 are coated with white inorganic particles 3.

Furthermore, when cobalt plating is applied to metal plating, most cobalt plating baths are composed of sulfur compounds such as potassium thiocyanate and sodium thiosulfate, and metallic cobalt compounds. Black inorganic particles and white inorganic particles are dispersed in a plating bath composed of cobalt metal ions, and as shown in Figure 2, the surfaces of the black inorganic particles 1 are coated with white inorganic particles 3 via a plating film 5. In this way, filled particles 4 are obtained in which the surfaces of the black inorganic particles 1 are coated with white inorganic particles 3.

Metal plating can also be performed on manganese (Mn), iron (Fe), and nickel (Ni). For example, manganese phosphate can be used for manganese (Mn), iron chloride can be used for iron (Fe), and nickel sulfamate can be used for nickel (Ni). This results in filled particles 4 in which the surfaces of black inorganic particles 1 are coated with white inorganic particles 3 via a plating film 5.

The photocurable resin composition of the embodiment can be obtained by dispersing filler particles, which are black inorganic particles whose surfaces are coated with white inorganic particles, into the photocurable resin described above. Various mixers can be used to disperse the filler particles into the photocurable resin. For example, a slurry of the photocurable resin composition can be produced by stirring the photocurable resin and filler particles to be mixed using a planetary mixer or the like.

(Method for producing photocured product)
The photocurable resin composition prepared as described above can be laminated by, for example, stereolithography to produce a laminated structure. Depending on the thickness of the photocured product (stereolithography), the desired photocured product may be obtained by a single stereolithography product without laminating the photocured products. The manufacturing process for the photocured product will be described with reference to FIG. 3.

First, as shown in FIG. 3(a), photocurable resin composition slurry 12A is applied to substrate 11. The photocurable resin composition slurry 12A is deposited on substrate 11, for example, by ejecting it from a syringe. Depending on the photocurable material, substrate 11 may be a structural component that serves as the base, or it may simply be a coating material for the slurry. Next, photocurable resin composition slurry 12 deposited on substrate 11 is smoothed with a squeegee 13. From the perspective of light penetration depth, the thickness of deposited layer 12B of smoothed slurry 12A is preferably set so that the cured thickness per layer is approximately 10 to 50 μm. Light penetration depth is an index that indicates the thickness to which a photocurable resin will cure when filler particles, consisting of black inorganic particles coated with white inorganic particles, are blended into the resin; a thickness of 10 μm or greater is preferred.

Next, as shown in FIG. 3(b), curing light L, such as ultraviolet light, is irradiated onto the required areas of the smoothed deposition layer 12B, photocuring the required areas of the deposition layer 12B to form a first cured layer 14A. Subsequently, a photocurable resin composition slurry 12A is again deposited on the deposition layer 12B having the first cured layer 14A (FIG. 3(c)), and the slurry 12A is then smoothed with a squeegee 13 to form a deposition layer 12C (FIG. 3(d)). Next, as shown in FIG. 3(e), curing light is irradiated onto the required areas of the deposition layer 12C, photocuring the required areas of the deposition layer 12C to form a second cured layer 14B on the first cured layer 14A.

By repeating the steps of depositing the photocurable resin composition slurry 12A, smoothing the photocurable resin composition slurry 12A, and curing by irradiation with curing light L according to the thickness of the photocured product, a photocured product 15 is produced, which has a laminate of a first cured layer 14A, a second cured layer 14B, and, if necessary, a third or more cured layers. In the photocured product production process of this embodiment, the surfaces of the black inorganic particles are coated with white inorganic particles, thereby suppressing absorption of the curing light L by the black inorganic particles. This allows the curing light L to reach the required depth in the deposited layers 12B and 12C of the photocurable resin composition slurry 12A, enabling successful photocuring of the deposited layers 12B and 12C.

Next, we will describe the photocurable resin composition of the embodiment, its manufacturing method, and specific examples of methods for manufacturing photocured products, as well as the evaluation results.

(Examples 1 to 5, Reference Example 1, Comparative Examples 1 and 2)
First, LSCF particles coated with gadolinium-doped ceria (GDC) particles were prepared as filler particles. In Example 1, an adhesive was used to coat the GDC particles. In Example 2, Ag plating was used, in Example 3, Co plating was used, in Example 4, Mn plating was used, in Example 5, Fe plating was used, and in Reference Example 1, Ni plating was used. In Comparative Example 1, LSCF particles not coated with GDC particles were used.

The above-described filler particles were blended into the photocurable resin at a ratio of 50 to 70% by volume. The low-viscosity photocurable resin TB1771E (product name, manufactured by ThreeBond Co., Ltd.) was used, and 10 to 50% by mass of M-350 (product name, manufactured by Toagosei Co., Ltd.) was blended as a dilution solvent for the photocurable resin, and 0.1 to 5% by mass of V-65 (product name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was blended as an azo thermal polymerization initiator, relative to the photocurable resin, to prepare the photocurable resin composition slurries of Examples 1 to 5 and Reference Example 1.

The photocuring depth of the photocuring resin composition slurries described above was measured. Here, as a simple property evaluation, a shim ring (e.g., 10 μm thick) was used as a spacer for film thickness control, and the photocuring depth of the slurries was measured by irradiating them with laser light (wavelength: 365 nm) from above to cure them. The results are shown in Table 1. As shown in Table 1, the photocuring depth of the photocuring resin composition slurries of Examples 1 to 5 and Reference Example 1 all achieved a photocuring depth of 10 μm or more, while the photocuring depth of the slurry of Comparative Example 1 was 1.0 μm or less. This demonstrates that coating the surfaces of black inorganic particles with white inorganic particles can improve the photocuring properties of photocuring resin composition slurries containing them.

Next, electrochemical cells were fabricated using oxygen electrodes fabricated using the photocurable resin composition slurries of Examples 1 to 5, Reference Example 1, and Comparative Example 1. As shown in FIG. 4, the electrochemical cell 21 includes a support layer 22, a hydrogen electrode 33, a solid oxide electrolyte layer 24, an intermediate layer 25, and an oxygen electrode 26. The oxygen electrode 26 of the electrochemical cell 21 was fabricated using the photocurable resin composition slurries of Examples 1 to 5, Reference Example 1, and Comparative Example 1. The oxygen electrode 26 was fabricated by baking the photocured slurry. Furthermore, in the electrochemical cell of Comparative Example 2, the oxygen electrode was formed by screen-printing LSCF and then baking it.

The cell performance of the electrochemical cells of Examples 1 to 5, Reference Example 1, and Comparative Examples 1 and 2 was measured. Cell performance is shown as a relative value, with the output of an electrochemical cell in which an oxygen electrode was formed using a conventional method being set at 1.0. The electrochemical cell characteristics were comprehensively evaluated based on the photocuring depth and cell performance. For cases in which the photocuring depth was 10.0 μm or greater and the cell characteristics exceeded 1.0, the overall evaluation was given as "Good." Cases in which only one of the above characteristics was satisfied were given a "Good" evaluation, and cases in which none of the above characteristics were satisfied were given an "Poor" evaluation. As shown in Table 1, Examples 1 to 5 all demonstrated favorable results. Although Reference Example 1 had inferior cell characteristics due to the use of Ni plating, the photocuring depth was good, and favorable characteristics were obtained in terms of the production of photocured products.

The configurations of the above-described embodiments can be applied in combination with each other, and some parts can be replaced with other parts. While several embodiments of the present invention have been described here, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, as well as the invention and its equivalents as set forth in the claims.

1...black inorganic particles, 2...adhesive, 3...white inorganic particles, 4...filler particles, 5...plating film.

Claims (8)

preparing a slurry of a photocurable resin composition;
molding a slurry of the photocurable resin composition;
irradiating a desired region of the molded product of the slurry of the photocurable resin composition with light to form a first photocured product of the photocurable resin composition;
molding a slurry of the photocurable resin composition onto a first photocured product of the photocurable resin composition;
and irradiating a desired region of the molded product of the slurry of the photocurable resin composition with light to form a second photocured product on the first photocured product of the photocurable resin composition,
the photocurable resin composition comprises a matrix resin that is cured by light irradiation, and filler particles that are dispersed in the matrix resin and contain black inorganic particles, the filler particles comprising the black inorganic particles and a white inorganic substance that is provided so as to cover surfaces of the black inorganic particles ;
A method for producing a photocurable product, comprising obtaining a laminate of the first photocurable product and the second photocurable product. 2. The method for producing a photocurable material according to claim 1, wherein the black inorganic particles contain at least one selected from the group consisting of lanthanum strontium cobalt iron oxide, iron, manganese, carbon, and boron carbide. 3. The method for producing a photocurable material according to claim 1, wherein the white inorganic substance comprises at least one selected from the group consisting of ceria, gadolinium-doped ceria, aluminum oxide, zirconium oxide, aluminum nitride, and barium titanate . 4. The method for producing a photocurable material according to claim 1, wherein the surfaces of the black inorganic particles are covered with white inorganic particles made of the white inorganic substance. The method for producing a photocurable material according to claim 4 , wherein the surfaces of the black inorganic particles are covered with the white inorganic particles via an adhesive. The method for producing a photocurable material according to claim 4 , wherein the surfaces of the black inorganic particles are coated with the white inorganic particles by powder plating. The method for producing a photocurable material according to claim 4 , wherein the surfaces of the black inorganic particles are covered with the white inorganic particles via a metal plating film. The method for producing a photocurable material according to claim 1 , wherein the first photocurable material or the laminate is an electrode material for an electrochemical cell.