JP2017014322A - Photosetting composition and cured article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosetting composition containing a heteropolyacid compound and a polymerizable compound and capable of forming an efficiently cured composite.SOLUTION: There is used a photosetting composition containing one kind or a plurality kinds of heteropolyacid compound and one kind or a plurality kind of polymerizable compound and one kind or a plurality kind of photoinitiator, where the heteropolyacid compound is selected from a group consisting of heteropolyacid containing tungsten and a salt thereof and heteropolyacid containing molybdenum and a salt thereof and the photoinitiator has absorption to light with wavelength of 400 nm or more.SELECTED DRAWING: None

Description

  The present invention relates to a photocurable composition containing a heteropolyacid containing tungsten and / or molybdenum and a photocurable resin, and a cured product in which a heteropolyacid and a cured photocurable resin are combined.

  Refractive index is one of the properties of a material. The refractive index is greatly affected by the constituent elements, molecular structure, crystal structure, and charge, and the modulation of the refractive index is not easy. Usually, the refractive index of a polymer made of an organic compound is limited to around 1.4 to 1.6, and lacks variations compared to inorganic materials of 0.17 (silver) to 4.2 (silicon). This is because the main component of the polymer is mainly carbon having low atomic refraction. However, in order to utilize the moldability and / or lightness of the polymer, in an optical material application such as a lens, an attempt to increase the refractive index of the polymer material by molecular design such as introduction of sulfur atom and / or bromine atom. Has been done. In addition, refractive index modulation is also performed by combining a polymer material and metal oxide fine particles having a high refractive index. This is because the refractive index modulation of the functional polymer cannot be achieved by rearranging the constituent elements. The metal oxide used includes alumina, titania, zirconia, and the like (see, for example, Patent Document 1). However, in order to increase the transparency of the composite material, it is necessary to uniformly disperse metal oxide fine particles having a particle size of several nm in the composite material. Therefore, it is not easy to produce a composite material containing metal oxide fine particles.

  In order to solve the above problems, a method for easily producing a complex of tungstic acid and / or molybdic acid and a polymer, and a high transparency obtained by the method, and a desired refractive index are obtained. Has been proposed (see Patent Document 2)

Japanese Patent Laid-Open No. 9-221598 International Publication No. 2013/191130

  However, when a composite of tungstic acid and / or molybdic acid and a polymer is photocured, sufficient curability cannot be obtained even when irradiated with light, and a cured product may not be formed. The present invention has been made to solve this problem, and an object of the present invention is to provide a photocurable composition having sufficient curability and a wide refractive index adjustment range.

  The photocurable composition of the first embodiment of the present invention comprises (a) one or more heteropolyacid compounds, (b) one or more polymerizable compounds, and (c) one or more A plurality of photopolymerization initiators, and the heteropolyacid compound is selected from the group consisting of a heteropolyacid containing tungsten and a salt thereof, and a heteropolyacid containing molybdenum and a salt thereof, and the photopolymerization initiator is It has absorption with respect to light with a wavelength of 400 nm or more. The photocurable composition of this embodiment may further contain (d) one or more solvents. Here, the boiling point of the solvent under normal pressure is 250 ° C. or less, and the solvent is preferably liquid at room temperature. Further, the content of the heteropolyacid compound (a) may be 50 to 95% by mass based on the mass of the photocurable composition excluding the component (d).

  The cured product of the second embodiment of the present invention is obtained by irradiating the photocurable composition of the first embodiment with light.

  By adopting the above configuration, it becomes possible to impart sufficient curability to the photocurable composition containing the heteropolyacid of tungsten and / or molybdenum and form a cured product. Moreover, in the obtained hardened | cured material, it becomes possible to adjust a refractive index in the wide range.

  Further, the cured product adopting the above configuration is a microlens array used for CCD, C-MOS sensor, etc .; a light scattering layer used for illumination and display; a light emitting element (organic EL element, light emitting diode (LED), semiconductor) (Including lasers, etc.), antireflection layers (films) used in displays, photovoltaic cells, optical filters, etc .; optical waveguide resists; display elements using photonic structures, distributed reflection (DBR) or distributed feedback (DFB) lasers It can be used as a multilayer reflective film used for a light confinement material used for an element; a scatterer of a random laser oscillation element; a spectral filter, a bandpass filter, and the like.

It is a graph which shows the relationship between content of the heteropoly acid compound in hardened | cured material, and the refractive index of hardened | cured material.

  The photocurable composition of the first embodiment of the present invention comprises (a) one or more heteropolyacid compounds, (b) one or more polymerizable compounds, and (c) one or more A plurality of photopolymerization initiators, and the heteropolyacid compound is selected from the group consisting of a heteropolyacid containing tungsten and a salt thereof, and a heteropolyacid containing molybdenum and a salt thereof, and the photopolymerization initiator is It has absorption with respect to light with a wavelength of 400 nm or more.

  In this embodiment, the heteropolyacid compound (a) is present uniformly in a state of being dissolved in the photocurable composition, not in a state of being dispersed as particles in the photocurable composition. By irradiating the photocurable composition of this embodiment with light, a cured product in which the heteropolyacid compound (a) is uniformly present can be obtained.

  The photopolymerization initiator contained in the photocurable composition of the present invention has absorption for light having a wavelength of 400 nm or more, and is polymerizable when irradiated with light having a wavelength of 400 nm or more. The polymerization of is started. Light having a wavelength of less than 400 nm is shielded by the heteropolyacid compound (a). Therefore, in a composition containing the heteropolyacid compound (a), a photopolymerization initiator that does not absorb light having a wavelength of 400 nm or longer cannot initiate polymerization even when irradiated with light. As a result, a composition containing a photopolymerization initiator that does not absorb light having a wavelength of 400 nm or more cannot obtain sufficient photocurability.

(A) Heteropolyacid compound The heteropolyacid compound used in the present embodiment is selected from the group consisting of a heteropolyacid containing tungsten and a salt thereof, and a heteropolyacid containing molybdenum and a salt thereof. Non-limiting examples of heteropolyacids containing tungsten and heteropolyacids containing molybdenum include silicotungstic acid (such as H ₄ [SiW ₁₂ O ₄₀ ]), phosphotungstic acid (such as H ₃ [PW ₁₂ O ₄₀ ]), molybdic acid (such as _{H 4 [SiMo 12 O 40]} ), ( such as _{H 3 [PMo 12 O 40]} ) phosphomolybdic acid, phosphoric tongue strike molybdic acid (such as _{H 3 [PW 12-x Mo} x O 40]), and Including phosphovanadmolybdic acid (such as H ₃ [PV _12-x Mo _x O ₄₀ ]). Specific examples of salts of these heteropolyacids include alkali metal salts such as sodium and potassium, and ammonium salts. Furthermore, the above-mentioned heteropolyacid and its salt may be a hydrate, or may be in a form with a low content of anhydride or crystal water obtained by heat-treating the hydrate. In this embodiment, one of the aforementioned heteropolyacids or salts thereof may be used, or two or more heteropolyacids or salts thereof may be used in combination.

  The refractive index of the cured product can be adjusted by adjusting the content of the heteropolyacid compound (a). The content of the heteropolyacid compound (a) is typically 50 to 95% by mass based on the mass of the photocurable composition excluding the solvent (d). By setting the content within such a range, it is possible to prevent the increase in cost and embrittlement of the cured product, and to adjust the refractive index of the cured product in a range higher than the range that can be adjusted with a general-purpose acrylate resin. It becomes possible. In addition, when using a hydrate as a heteropolyacid compound (a), the mass of hydration water is excluded from the mass of a heteropolyacid compound (a) and the total mass of a composition. That is, the content of the heteropolyacid compound (a) is calculated by the following formula.

  Furthermore, the content of the heteropolyacid compound (a) in the cured product after photocuring can be determined by thermal mass spectrometry-differential thermal analysis (TG-DTA) in which the cured product is heated to 550 ° C. in the presence of oxygen. . By performing TG-DTA under the above conditions, the mass of the remaining hydrated water and solvent (d), and the mass of the resin component derived from the polymerizable compound (b) and the photopolymerization initiator (c), The mass of the heteropolyacid or its salt (not including hydrated water) in the heteropolyacid compound (a) can be clearly distinguished and quantified.

(B) Polymerizable compound The polymerizable compound used in this embodiment includes a polyfunctional component having two or more ethylenic carbon-carbon double bonds per molecule. Preferred examples of multifunctional components include acrylates or methacrylates having two or more ethylenic carbon-carbon double bonds per molecule. Here, the ethylenic carbon-carbon double bond is preferably present in the form of an acrylic group or a methacrylic group. Hereinafter, “acrylate” and “methacrylate” are collectively referred to as “(meth) acrylate”. Alternatively, a compound other than (meth) acrylate having two or more ethylenic carbon-carbon double bonds per molecule may be used as the multifunctional component. Furthermore, as long as sufficient curability is obtained, the polymerizable compound may contain a monofunctional component having one ethylenic carbon-carbon double bond per molecule.

  The polymerizable compound can be appropriately selected from known materials on the condition that the heteropolyacid compound (a) can be uniformly dispersed or dissolved. For example, non-limiting examples of multifunctional components that can be used include the following materials:

(I) Bifunctional (meth) acrylate Alkanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, N, N′-methylenebis (meth) acrylamide, bisphenol A di (meta) ) Acrylate.

(Ii) Trifunctional or higher (meth) acrylates Trimethylolpropane tri (meth) acrylate, ethylene oxide (EO) modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris (2- (meth) acryloyloxyethyl) isocyanurate.

  Alternatively, divinylbenzene, diallylbenzene, trivinylbenzene, divinylcyclohexane, diallylcyclohexane, bisphenol A diallyl ether, triallyl isocyanurate, or the like may be used as a multifunctional component.

  Non-limiting examples of monofunctional components that can be used include the following materials.

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate;
n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, isodecyl (meth) acrylate, lauryl ( (Meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate;
Glycidyl (meth) acrylate, acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate , Methoxypropylene glycol (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, ethyl carbitol (meth) acrylate;
Dimethylaminoethyl (meth) acrylate;
Trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate;
Adamantyl (meth) acrylate derived from 2-adamantane or adamantanediol and having one mono (meth) acrylate;
Phosphorylated alkyl (meth) acrylate, EO-modified alkyl phosphorylated (meth) acrylate.

  Alternatively, the polymerizable compound may further include a polymerizable oligomer or a polymerizable polymer. Examples of oligomers having polymerizability include epoxy oligomers containing ethylenic carbon-carbon double bonds in the side chains, urethane oligomers containing ethylenic carbon-carbon double bonds in the side chains, and ethylenic carbon-carbon doubles in the side chains. Including polyester oligomers containing heavy bonds. Examples of the polymer having polymerizability include various polymers containing an ethylenic carbon-carbon double bond in the side chain.

  The polymerizable compound of this embodiment may be composed of one kind of multifunctional component. Alternatively, the polymerizable compound of the present embodiment includes at least one multifunctional component, two or more multifunctional components, a monofunctional component, a polymerizable oligomer and / or polymerization. It may be a mixture of polymers having properties.

(C) Photoinitiator The photocurable composition of this embodiment contains 1 type or multiple types of photoinitiator which has absorption with respect to the light which has a wavelength of 400 nm or more. In this specification, “having absorption with respect to light having a wavelength of 400 nm or more” means that the absorbance is 0.2 or more when a 0.1% by mass acrylonitrile solution is measured with an optical path length of 1 cm. It means that the wavelength exists in the region of 400 nm or more. The photopolymerization initiator generates radicals when irradiated with light containing a component that achieves the above absorbance. The photopolymerization initiator that can be used can be appropriately selected from acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like. Non-limiting examples of photoinitiators that have absorption for light having a wavelength of 400 nm or more include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -Phenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone.

  The photocurable composition of the present embodiment is typically 0.1 parts by mass or more and 20 parts by mass or less, preferably 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymerizable compound (b). Photopolymerization initiator (c).

(D) Solvent The photocurable composition of this embodiment may further contain a solvent for the purpose of adjusting the viscosity. The solvent that can be used includes a compound having a boiling point of 250 ° C. or less at normal pressure (atmospheric pressure) and liquid at normal temperature (25 ° C.). The solvent is required to be able to dissolve the material used for the photocurable composition. Non-limiting examples of solvents that can be used are:
water;
Ethers such as dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, trioxane, tetrahydrofuran, anisole and phenetole;
Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone;
Esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propion brewed ethyl, n-pentyl acetate, 2-ethoxyethyl acetate, and γ-butyrolactone;
Alcohols such as ethanol, isopropyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol; and amides such as dimethylformamide and dimethylacetamide.

  In this embodiment, one type of solvent may be used, or a mixture of two or more types of solvents may be used.

(E) Additive The photocurable composition of the present embodiment may further contain any additive known in the technical field to which the desired application belongs. Additives that can be used include, for example, photosensitizers, chain transfer agents, surface conditioners, antioxidants, adhesion improvers, mold release agents and the like.

  The cured product of the second embodiment of the present invention is formed by irradiating the photocurable composition of the first embodiment with light.

  The cured product of this embodiment is formed by a method including (1) a step of forming a film of a photocurable composition and (2) a step of irradiating light to the film of the photocurable composition. If necessary, a step (1 ′) of drying the film of the photocurable composition may be performed between the steps (1) and (2). Moreover, you may implement the process of annealing (3) hardened | cured material after a process (2). Hereinafter, each process will be described.

(1) Step of forming a film of a photocurable composition This step can be performed using any technique known in the art such as coating, casting, casting (casting), and extrusion. .

  When performing this process using application | coating, a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, a knife coater, a bar coater, a wire bar coater, a die coater, a dip coater, etc. can be used. Here, a sheet-fed system in which a photocurable composition is applied to a sheet-like substrate may be used, or a photocurable composition is applied to a roll-like substrate, and then the substrate is wound on a roll. A roll-to-roll method may be used. In addition, when using a roll-to-roll system, it implements the process of irradiating light to the film | membrane of a photocurable composition mentioned later between application | coating and winding, and hardened | cured material before winding up Alternatively, the above film may be formed. In particular, it is preferable to use a roll-to-roll method. Because, in the roll-to-roll method, the base material is continuously run from the unwinding part (supplying part) to the winding part via the application part and optionally the light irradiation part, It is because the film of a photocurable composition or hardened | cured material can be manufactured continuously. When the roll-to-roll method is used, the base material typically has a film thickness of 25 μm to 200 μm, preferably 40 μm to 80 μm.

  When this step is performed using a casting mold, irregularities can be formed on the surface of the finally obtained cured product by imparting irregularities to the surface of the mold. Moreover, even if it implements the process which irradiates light to the film | membrane of a photocurable composition in a type | mold, using the type | mold formed with the material which is transparent with respect to the light of a wavelength of 400 nm or more. Good.

  The base material used in this step includes any material known in the art. Non-limiting examples of materials that make up the substrate include glass, silicon, and thermoplastic materials such as polyethylene, polymethyl methacrylate, polyethylene terephthalate. Alternatively, depending on the use of the cured product, the substrate may have various functional parts formed on the aforementioned material. For example, what formed an organic EL element, various laser elements, a photovoltaic cell, a light receiving element etc. on the silicon wafer may be used as a substrate of this process.

(1 ') The process of drying the film | membrane of a photocurable composition If necessary, the process of drying the film | membrane of a photocurable composition is provided between the process (1) and the process (2) mentioned later. Also good. In particular, it is useful for distilling off the solvent when the photocurable composition contains a solvent. This step includes a method of passing a photocurable composition film through a drying furnace, a method of spraying dry air on the photocurable composition film, a method of heating the photocurable composition film, and the like. It can be carried out in any way known in the art. Drying ovens that can be used include radial drying ovens, circulating air drying ovens, and the like. Moreover, a hot air fan etc. can be used for formation of dry air. A heating roll, an infrared heater, or the like can be used to heat the film of the photocurable composition.

(2) The process of irradiating light to the film | membrane of a photocurable composition Then, light is irradiated to the film | membrane of a photocurable composition, photocuring is raise | generated, and hardened | cured material is formed. In this step, any light source known in the art can be used on condition that light with a wavelength of 400 nm or more can be irradiated with sufficient intensity. Light sources that can be used include high pressure mercury lamps, low pressure mercury lamps, ultra high pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon arc lamps, and the like.

  Here, when it is required to form a predetermined pattern such as irregularities on the surface of the cured product, light is irradiated in a state where a stamper having an inverted shape of the predetermined pattern is pressed against the film of the photocurable composition. May be. When the stamper is formed of a material that transmits light having a wavelength of 400 nm or more, light irradiation may be performed through the stamper. After the photocuring is finished, a predetermined pattern can be obtained by removing the stamper. In addition, when the photocurable composition itself has sufficient consistency to maintain the shape even after the stamper is removed, light may be irradiated after the stamper is removed.

  Alternatively, when it is required to form a cured product only in a partial region on the substrate, light may be irradiated through a photomask having a predetermined pattern. Subsequent to the light irradiation, the photocurable composition in the region not irradiated with light can be removed by washing with a solvent or the like. On the other hand, in the region irradiated with light, photocuring proceeds to obtain a cured product. This method is particularly effective when a cured product is formed only at a predetermined position on a base material including functional parts.

(3) Step of annealing the cured product The cured product of this embodiment may be annealed. “Annealing” in the present invention means a process of heating an object to an appropriate temperature, maintaining the object at the temperature for a predetermined time, and then gradually cooling the object. The heating temperature may be within a range of 50 ° C to 200 ° C, for example. Moreover, the time which hold | maintains a target object at the above-mentioned heating temperature may be in the range of 5 minutes-120 minutes, for example.

  The annealing treatment is useful for increasing the hardness of the cured product, improving water resistance, and improving solvent resistance.

  The hardened | cured material obtained by the method demonstrated above can have a refractive index of the range higher than the range (about 1.4-1.6) which can be adjusted with a general purpose acrylate resin. The refractive index can be adjusted by changing the content of the heteropolyacid compound (a). More specifically, the cured product of this embodiment can have a refractive index in the range of about 1.55 to about 1.80.

  Therefore, the cured product of this embodiment is useful in applications that require a high refractive index and / or high moldability. For example, the cured product of this embodiment is a microlens array used for CCDs, C-MOS sensors, etc .; a light scattering layer used for illumination and display; Antireflection layer (film) used in displays, photovoltaic cells, optical filters, etc .; optical waveguide resists; display elements using photonic structures, distributed reflection (DBR) type or distributed feedback (DFB) type laser elements It is believed that it can be applied to a multilayer reflective film used for a light confinement material used; a scatterer of a random type laser oscillation element;

Example 1
The following materials were mixed to prepare a photocurable composition.
(A) Heteropoly acid compound Silicotungstic acid 26 hydrate (SiW12, Wako Pure Chemical Industries, Ltd.) 69.9 parts by mass (b) polymerizable compound;
Trimethylolpropane triacrylate (TMPTA, Osaka Organic Chemical Co., Ltd.) 38.0 parts by mass; and (c) Photopolymerization initiator 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Lucirin TPO, manufactured by BASF) 2.0 parts by weight.

  When the material was difficult to dissolve, it was heated to 50 ° C. to 60 ° C. and completely dissolved. When excluding hydration water, the content of the heteropolyacid compound (a) in the above composition was 60% by mass. In addition, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide had absorption for light having a wavelength of 400 nm or more.

The obtained photocurable composition was apply | coated on the glass base material using the wire bar coater. The coating amount of the composition was prepared so that the film thickness after curing was 7 μm. Subsequently, with the aid of a conveyor type ultraviolet curing device, the film of the photocurable composition was irradiated with light from a high-pressure mercury lamp to obtain a cured film. The amount of light irradiation was set to 300 mJ / cm ² .

(Examples 2, 3, and 8)
The composition of the photocurable composition was changed to a composition containing the solvent shown in Table 1, and the coating using a wire bar coater was followed by drying in an oven at 50 ° C. for 1 minute. Except for the above, a cured film was obtained by repeating the procedure of Example 1.

  Examples 2, 3 and 8 relate to photocurable compositions using ethyl acetate as the solvent. In Example 3, the photopolymerization initiator was changed to bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide having absorption with respect to light having a wavelength of 400 nm or longer.

(Examples 4 to 7 and 9, Comparative Examples 1 and 2)
A cured film was obtained by repeating the procedure of Example 1 except that the composition of the photocurable composition was changed to a composition containing a solvent shown in Table 1.

  In Example 9, phosphotungstic acid 30 hydrate was used in place of silicotungstic acid 26 hydrate as the heteropolyacid compound. In Comparative Example 1, the photopolymerization initiator was changed to 2,2-dimethoxy-2,2-diphenylethane-1-one that does not absorb light having a wavelength of 400 nm or longer. In Comparative Example 2, the photopolymerization initiator was changed to 2-hydroxy-2-methyl-1-phenylpropan-1-one that does not absorb light with a wavelength of 400 nm or longer.

(Evaluation 1)
A finger touch test was performed on the cured films obtained in Examples 1 to 9 and Comparative Examples 1 and 2, and the curability of the photocurable composition was evaluated. The results are shown in Table 1.

  From the results of Examples 1 to 3, the photocurable composition containing a photopolymerization initiator having absorption with respect to light having a wavelength of 400 nm or more has sufficient curability regardless of the presence or absence of a solvent. I understood. In addition, from the results of Examples 4 to 8, photocuring including a photopolymerization initiator having absorption with respect to light having a wavelength of 400 nm or longer, even when the usage amount of the heteropolyacid compound, the polymerizable compound, and the photopolymerization initiator is changed. The composition was found to have sufficient curability. Furthermore, from the result of Example 9, even when different types of heteropolyacid compounds are used, the photocurable composition containing a photopolymerization initiator having absorption with respect to light having a wavelength of 400 nm or more is sufficiently curable. It was found to have

  In contrast, the photocurable compositions of Comparative Example 1 and Comparative Example 2 containing a photopolymerization initiator that does not absorb light having a wavelength of 400 nm or longer remain tacky even after light irradiation, and photocuring Was found to not progress sufficiently. This is presumably because the curing reaction did not proceed because the heteropolyacid compound shielded the light of the wavelength component absorbed by the photopolymerization initiator.

(Evaluation 2)
About the hardened | cured material obtained in Example 1 and 4-8, the refractive index in the wavelength of 633 nm was measured using the reflective spectral film thickness meter FE-3000 (made by Otsuka Electronics Co., Ltd.). The results are shown in Table 2 and FIG. The “content of the heteropolyacid compound” shown in Table 2 and FIG. 1 is based on the mass of the photocurable composition excluding the solvent (d), as described above, and the hydration of the heteropolyacid compound. It is a mass percentage in which water is regarded as a solvent.

  From Table 2 and FIG. 1, it can be seen that the refractive index of the cured product increases as the content of the heteropolyacid compound increases. Moreover, linearity is recognized between content of a heteropolyacid compound and the refractive index of hardened | cured material from FIG. Furthermore, the range of the refractive index of the obtained cured product was 1.570 to 1.782, which was higher than the range (about 1.4 to 1.6) that can be adjusted with a general-purpose acrylate resin. From these, it can be seen that the cured product of the present invention has a large refractive index, and that the refractive index of the cured product of the present invention can be adjusted by the composition of the photocurable composition.

(Effect of annealing treatment)
About the hardened | cured material obtained in Examples 1-9, it heated to 130 degreeC over 10 minutes, and was then left to stand in 25 degreeC air, and was gradually cooled, the increase in the hardness of hardened | cured material and the improvement of water resistance And, the improvement of solvent resistance was confirmed.

Claims (4)

(A) one or more heteropolyacid compounds;
(B) one or more polymerizable compounds;
(C) one or more photopolymerization initiators,
The heteropolyacid compound is selected from the group consisting of a heteropolyacid containing tungsten and a salt thereof, and a heteropolyacid containing molybdenum and a salt thereof,
The photopolymerization initiator has absorption with respect to light having a wavelength of 400 nm or more. (D) The photocurable composition according to claim 1, further comprising one or more solvents, wherein the solvent has a boiling point of 250 ° C. or less under normal pressure, and the solvent is liquid at room temperature. Composition.   The content of the heteropolyacid compound (a) is 50 to 95% by mass based on the mass of the photocurable composition excluding the component (d). Photocurable composition.   Hardened | cured material obtained by irradiating light to the photocurable composition of Claims 1-3.