High refractive index curable composition and high refractive index cured product

Abstract

To provide a high refractive index curable composition that can produce high refractive index cured products that achieve both high refractive index and thermal stability. [Solution] A high refractive index curable composition containing a metal alkoxy oligomer complex represented by the following general formula (1), wherein a ligand is coordinated to a metal alkoxy oligomer, inorganic nanoparticles, a photopolymerizable compound, and a polymerization initiator, wherein the metal of the metal alkoxy oligomer complex is a metal element of group 4, 5, 13, 14, or 15, and the number average molecular weight of the metal alkoxy oligomer is 1000 or more. [Formula 1] JPEG2026076638000009.jpg2765

Description

Technical Field

[0001] The present invention relates to a high refractive index curable composition and a high refractive index cured product.

Background Art

[0002] In optical elements such as solar cells and lenses, and optical components such as coating films, coatings using materials having a high refractive index and resin compositions for high refractive index layers are known.

[0003] So far, in a composite coating, a resin having a polymer network structure containing a polymer having a repeating unit derived from an acrylic or methacrylic monomer or oligomer, and inorganic nanoparticles disposed in the resin, have been reported, and a composite coating having a refractive index exceeding 1.7 and a glass transition point exceeding 60°C (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a demand for a high refractive index curable composition that can achieve a further high glass transition point and can produce a high refractive index cured product having both a high refractive index and thermal stability.

[0006] An object of the present invention is to solve the above-mentioned conventional problems and achieve the following object. That is, an object of the present invention is to provide a high refractive index curable composition capable of producing a high refractive index cured product having both a high refractive index and thermal stability.

Means for Solving the Problems

[0007] The means to solve the aforementioned problem are as follows: <1> A metal alkoxy oligomer complex represented by the following general formula (1), in which a ligand is coordinated to a metal alkoxy oligomer, Inorganic nanoparticles and Photopolymerizable compounds, It contains a polymerization initiator and The metal in the aforementioned metal alkoxy oligomer complex is a metallic element from groups 4, 5, 13, 14, and 15. The high refractive index curable composition is characterized in that the number average molecular weight of the metal alkoxy oligomer is 1000 or more. [ka] In the general formula (1) above, M represents a metal, R independently represents an alkyl group having 1 to 18 carbon atoms, L represents a ligand, and n represents an integer of 1 or more. <2> The ligand content in the metal alkoxide oligomer complex is 0.1 moles or more and 3 moles or less per mole of metal in the metal alkoxide oligomer complex. <1> This is the high refractive index curable composition described above. <3> The particle size of the inorganic nanoparticles is 1 nm or more and 100 nm or less. <1> or <2> This is the high refractive index curable composition described above. <4> The inorganic nanoparticles have a content of 40% by mass or more and 80% by mass or less. <1> from <3> The high refractive index curable composition is as described in any of the above. <5> The content of the photopolymerizable compound is 1% by mass or more and 20% by mass or less. <1> from <4> The high refractive index curable composition is as described in any of the above. <6> The content of the metal alkoxide oligomer complex is 15% by mass or more and 55% by mass or less. <1> from <5> The high refractive index curable composition is as described in any of the above. <7> The mass ratio (A / B) of the metal alkoxide oligomer complex (A) to the photopolymerizable compound (B) is 50 / 50 to 90 / 10. <1> from <6> The high refractive index curable composition is as described in any of the above. <8> The metal of the metal alkoxy oligomer complex is titanium. <1> from <7> The high refractive index curable composition is as described in any of the above. <9> The inorganic nanoparticles are titanium oxide. <1> from <8> The high refractive index curable composition is as described in any of the above. <10> The aforementioned <1> from <9> This is a high refractive index cured product characterized by being obtained by photocuring a high refractive index curable composition described in any of the above. <11> The refractive index n at a wavelength of 636 nm is 1.70 or greater. <10> This is a high refractive index hardened product as described above. <12> The glass transition temperature measured by differential scanning calorimetry is 70°C or higher. <10> or <11> This is a high refractive index hardened product as described above. [Effects of the Invention]

[0008] According to the present invention, it is possible to solve the aforementioned problems in the conventional methodology, achieve the aforementioned objectives, and provide a high refractive index curable composition that can produce high refractive index cured products that can achieve both high refractive index and thermal stability. [Modes for carrying out the invention]

[0009] (High refractive index curable composition) The high refractive index curable composition of this embodiment comprises a metal alkoxide oligomer complex represented by the following general formula (1), inorganic nanoparticles, a photopolymerizable compound, and a polymerization initiator, and optionally includes other components such as a solvent.

[0010] Many optical products utilize technologies that involve the reflection and refraction of light, and the refractive index significantly influences the properties of refraction. For collimating lenses used in optical transceivers and other applications requiring extremely high optical properties, aspherical lenses produced by glass molding are the mainstream. These lenses are characterized by their high refractive index (1.8 or higher) and the ability to produce high-quality lenses with minimal aberrations. However, challenges include production costs due to high temperatures and cooling processes during the molding process, which degrade the molds, and the difficulty in designing compact lenses to meet the trend towards miniaturization of optical transceivers. As an alternative, a manufacturing process using nanoimprint lithography with resin compositions is being investigated.

[0011] One method for increasing the refractive index of resins used in such applications is to introduce chemical structures with a high refractive index. Specific examples of such chemical structures include phenyl groups and sulfur (see, for example, Patent Document 1). However, high refractive index materials consisting solely of resins with many rigid chemical structures and high refractive index have problems such as lack of thermoplasticity, making molding difficult, and susceptibility to degradation due to decomposition by light and oxygen (see, for example, Reference: Higashihara et al., Graduate School of Science and Engineering, Tokyo Institute of Technology, Proceedings of the Society of Polymer Science, Japan, 2011). Therefore, it is difficult to achieve a refractive index of 1.70 or higher and a glass transition temperature of 70°C or higher with a single resin, and in reality, no usable resin exists.

[0012] Another method for increasing the refractive index involves dispersing high refractive index metal oxide nanoparticles in the resin. In optical applications, high transmittance is generally required, and nanoscale metal oxide particles are often used to suppress transmittance reduction due to light scattering. However, uniform dispersion of metal nanoparticles in resin is generally difficult, raising concerns about refractive index unevenness and reduced transmittance due to aggregation. Furthermore, increasing the refractive index requires the addition of large amounts of metal oxide nanoparticles, which can lead to increased viscosity and decreased mechanical properties such as thermal stability. Therefore, improving the refractive index and thermal stability of the resin itself used in combination remains a development challenge, and there is still a need for the development of high refractive index curable compositions that can produce high refractive index cured products that achieve both high refractive index and thermal stability.

[0013] In order to solve the above-mentioned conventional problems and achieve the above object, the present inventors have conducted intensive studies. As a result, they have found that the high refractive index curable composition can produce a high refractive index cured product that can achieve both high refractive index and thermal stability, and thus have completed the present invention.

[0014] <Metal alkoxide oligomer complex> The metal alkoxide oligomer complex is represented by the following general formula (1) and is a complex compound in which a ligand is coordinated to a metal alkoxide oligomer. Here, "coordinating a ligand to a metal alkoxide oligomer" means that the ligand is coordinately bonded to the metal in the metal alkoxide oligomer. The metal of the metal alkoxide oligomer complex is a metal element of Group 4, 5, 13, 14, or 15, and the number average molecular weight of the metal alkoxide oligomer is 1000 or more.

Chemical formula

[0015] The metal alkoxide oligomer is represented by, for example, the following formula (2).

Chemical formula

[0016] In addition, the reaction of coordinating a ligand to a metal alkoxide oligomer to form an oligomer complex is represented by, for example, the following reaction formula (3).

Chemical formula

[0017] It is estimated that the following effects and benefits can be obtained by using a metal alkoxide oligomer complex, in which a ligand is coordinated to a metal alkoxide oligomer, and a photopolymerizable compound in combination with inorganic nanoparticles. Specifically, a polymer that becomes a binder resin is formed by photopolymerization of the metal alkoxide oligomer complex and the photopolymerizable compound. In this case, if the ligand of the metal alkoxide oligomer complex further has a polymerizable functional group, the metal alkoxide oligomer complex is incorporated into the polymer of the photopolymerizable compound. Furthermore, by heat treatment, the unreacted alkoxide in the metal alkoxide oligomer complex is removed as an alcohol, and the metal alkoxide oligomers form three-dimensional crosslinks, further improving the uniformity of the polymer. As a result, the uniformity of the polymer is improved compared to metal alkoxide monomers and oligomers, the glass transition temperature is raised, and the abundance of metal elements with high refractive index is increased, so a high refractive index cured product with an improved refractive index can be obtained. By using inorganic nanoparticles with a higher refractive index than organic materials, the refractive index can be increased. Furthermore, the increase in refractive index and glass transition temperature due to polymers containing metal alkoxide oligomer complexes allows for a reduction in the content of photopolymerizable compounds with relatively low refractive indices, making it possible to produce high-refractive-index cured products that achieve both even higher refractive indices and greater thermal stability.

[0018] As a method for identifying metal alkoxyd oligomer complexes obtained by coordinating ligands to metal alkoxyd oligomers, specifically, refer to reference: J. Materi. Chem. C, 2017, 5, 5487-5493, and use a Fourier transform infrared (FT-IR) spectrometer (e.g., Thermo Fisher Scientific Nicolet iS10) to identify the 1710 cm² vibration originating from the carbonyl stretching vibration of the carboxyl group observed in the metal alkoxyd oligomer before coordination. -1 The nearby peak disappears, and the 1550 cm⁻¹ is derived from the CO stretching vibration after coordination. -1 One method of identification is to confirm the observation of a newly observed peak.

[0019] In the above general formulas (1) and (2), M is a metal (central metal). The R is an alkyl group having 1 to 18 carbon atoms, preferably an alkyl group having 3 to 4 carbon atoms. Examples of suitable R groups include n-isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl. Furthermore, each R may be the same or different from one another. O is oxygen, OR is an alkoxide, and some ORs may be OH. n is an integer greater than or equal to 1. Regarding the number of carbon atoms in R, hydrolysis condensation reactivity is high when there are 1 or 2 carbon atoms, and decreases as the number of carbon atoms increases. Therefore, it can be appropriately selected depending on the desired reactivity and cured product, but from the viewpoint of reaction control, 3 to 4 carbon atoms are preferred. Metal alkoxide oligomer complexes in which R has more than 18 carbon atoms will have low hydrolysis condensation reactivity, and there is a possibility that a cured product cannot be obtained.

[0020] The number average molecular weight of the metal alkoxide oligomer is not particularly limited as long as it is 1000 or more, and can be appropriately selected depending on the purpose. However, in order to maintain the liquid viscosity when the complex obtained from the metal alkoxide oligomer is incorporated and the uniformity within the system during the sol-gel reaction, a number average molecular weight of 1000 to 10000 is preferred, and a number average molecular weight of 1000 to 3000 is more preferred. Methods for calculating the number-average molecular weight include, for example, gel permeation chromatography (GPC).

[0021] The aforementioned metal M is not particularly limited as long as it is a metallic element belonging to groups 4, 5, 13, 14, or 15, and can be appropriately selected depending on the purpose, but titanium (Ti) is preferred. The metal may also be a metal cluster containing two or more identical or different metals.

[0022] The ligand L is not particularly limited and can be appropriately selected depending on the purpose. It may be an inorganic mineral or an organic compound, and may be a monodentate ligand or a polydentate ligand with two or more dentates. In the general formula (1) above, the dashed line between the metal M and the ligand L represents a coordination bond, and the number of coordination bonds can be appropriately selected depending on the combination of the metal M and the ligand L.

[0023] The ligand coordinating to the metal alkoxide oligomer complex may be one type or two or more types. From the viewpoint of stability, a polydentate ligand is preferred, and a bidentate ligand is more preferred. Furthermore, from the viewpoint of improving the crosslinking density and thermal stability of the cured product, it is preferable that, in addition to the group coordinating to the metal, the complex has polymerizable functional groups that can polymerize with the photopolymerizable compound. Examples of groups that coordinate to the aforementioned metal include carboxyl groups, β-diketone moieties, amino groups, phosphino groups, and thiol groups. The polymerizable functional group can be any group that can polymerize with the photopolymerizable compound, such as an (meth)acryloyl group or an ethylenically unsaturated group such as a vinyl group.

[0024] Examples of bidentate ligands include carboxylic acids, carboxy(meth)acrylates, and β-diketones. Among these, carboxy(meth)acrylate is preferred because it has a carboxyl group that coordinates with a metal and a polymerizable functional group, and an increase in Tg is expected through crosslinking with a photopolymerizable compound. Examples of the carboxy(meth)acrylate include 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, and 1-(2-acryloyloxyethyl) phthalate.

[0025] Among the metal alkoxide oligomer complexes represented by the general formula (1) above, the metal alkoxide oligomer complex represented by the following general formula (4) is preferred. Here, in the general formula (4) above, M is titanium, R is an alkyl group having 3 to 4 carbon atoms, preferably an n-butyl group, and some of OR may be OH, R 1 R is an ethylene group or a benzyne group (a divalent benzene ring), 2 It is either a hydrogen atom or a methyl group.

[0026] [ka]

[0027] There are no particular restrictions on the ligand content in the metal alkoxide oligomer complex, and it can be appropriately selected depending on the purpose. However, the ligand content is preferably 0.1 moles or more and 3 moles or less per mole of metal in the metal alkoxide oligomer complex, more preferably 0.3 moles or more and 2.5 moles or less, and even more preferably 0.5 moles or more and 2 moles or less. If the ligand content exceeds 3 moles, the refractive index of the entire cured product may decrease. Also, if the ligand content is less than 0.1 moles, the amount of complex formation with the metal alkoxide oligomer is small, which may lead to deterioration of the uniformity of the polymer due to a rapid sol-gel reaction.

[0028] There are no particular restrictions on the content of the metal alkoxide oligomer complex, and it can be appropriately selected depending on the purpose. However, it is preferably 15% by mass or more and 55% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, relative to the total amount of the high refractive index curable composition. If the content exceeds 55% by mass, the film-forming ability may decrease due to the large amount of alcohol elimination components due to the sol-gel reaction. If the content is less than 15% by mass, the refractive index of the cured product may decrease because the effect of the metal alkoxide oligomer is small.

[0029] <Inorganic nanoparticles> The inorganic nanoparticles mentioned above are not particularly limited as long as they are nanoparticles with a high refractive index, and can be appropriately selected according to the purpose. Examples include metal oxide nanoparticles, metal nanoparticles, and alloy nanoparticles. Examples of materials for the aforementioned metal oxide nanoparticles include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and antimond-doped tin oxide (ATO). Examples of metals in the aforementioned metal nanoparticles include iron, zinc, tungsten, and platinum. Examples of alloys in the aforementioned alloy nanoparticles include alloys containing the aforementioned metals. These may be used individually or in combination of two or more types. Among these, metal oxide nanoparticles are preferred, and titanium oxide is more preferred.

[0030] There are no particular restrictions on the particle size of the inorganic nanoparticles, and they can be appropriately selected depending on the purpose, but a size of 1 nm to 100 nm is preferred, and a size of 5 nm to 50 nm is more preferred. The particle size can be measured by dynamic light scattering when the sample is a high refractive index curable composition or dispersion containing inorganic nanoparticles, or when the sample is a high refractive index cured product, by calculating the equivalent circle diameter within the observation field of view by observing a fragment using a transmission electron microscope (TEM).

[0031] There are no particular restrictions on the content of the inorganic nanoparticles, and they can be appropriately selected depending on the purpose. However, it is preferably 40% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 70% by mass or less, relative to the total amount of the high refractive index curable composition.

[0032] <Photopolymerizable compound> The aforementioned photopolymerizable compound is not particularly limited as long as it is a compound (polymerizable monomer) that can polymerize to form a resin, and can be appropriately selected depending on the purpose. Examples include (meth)acrylate, (meth)acrylamide, epoxy, thiol-containing compounds, polycarbonate, alkylene oxide, imide, amide, olefin, ester, styrene, silicone, and urethane.

[0033] Examples of the aforementioned resins include (meth)acrylic resin, (meth)acrylamide resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyphenylene resin, polyarylene ether phosphine oxide resin, polyimide resin, polyamide resin, polyolefin resin, cyclic olefin resin, polyester resin, styrene resin, silicone resin, and urethane resin.

[0034] The aforementioned photopolymerizable compound may be used alone or in combination of two or more types. Among these, (meth)acrylate is preferred from the viewpoint of moldability of the resin. Furthermore, from the viewpoint of increasing the refractive index, photopolymerizable compounds having a cyclic structure are preferred, and from the viewpoint of the thermal stability of the cured product, photopolymerizable compounds having polyfunctional polymerization groups are preferred.

[0035] There are no particular restrictions on the (meth)acrylate, and it can be appropriately selected depending on the purpose. Examples include alkyl (meth)acrylate, cycloalkyl (meth)acrylate, bicycloalkyl (meth)acrylate, tricycloalkyl (meth)acrylate, heterocycloalkyl (meth)acrylate, heterobicycloalkyl (meth)acrylate, naphthalene-containing (meth)acrylate, fluorene-containing (meth)acrylate, and hydroxyl group-containing (meth)acrylate. Among these, (meth)acrylates having cyclic structures such as cycloalkyl groups, naphthalene structures, and fluorene structures are preferred from the viewpoint of increasing the refractive index, and polyfunctional (meth)acrylates are preferred from the viewpoint of the thermal stability of the cured product.

[0036] Specific examples of the (meth)acrylates mentioned above include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, ethylene oxide adduct methacrylate of bisphenol A, trimethylolpropane trimethacrylate, and tricyclodecane dimethanol dimethacrylate. Examples include trimethylolpropane trimethacrylate, ethoxylated isocyanurate triacrylate, ε-caprolactone modified tris-(2-acryloxyethyl) isocyanurate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol polyacrylate, dipentaerythritol hexaacrylate, 1-naphthalene methyl acrylate, and dimethylol tricyclodecane diacrylate.

[0037] Examples of photopolymerizable compounds other than the (meth)acrylates mentioned above include triallyl isocyanurate, triallyl cyanurate, divinylbenzene, divinyl isophthalate, N-phenyl-maleimide, N-phenyl-methylmaleimide, N-phenyl-chloromaleimide, Np-chlorophenyl-maleimide, Np-methoxyphenyl-maleimide, Np-methylphenyl-maleimide, Np-nitrophenyl-maleimide, Np-phenoxyphenyl-maleimide, Np-phenylaminophenyl-maleimide, Np-phenoxycarbonylphenyl-maleimide, and 1-maleimide-4-acetoxysuccinimide-ben. Examples include zen, 4-maleimide-4'-acetoxysuccinimide-diphenylmethane, 4-maleimide-4'-acetoxysuccinimide-diphenyl ether, 4-maleimide-4'-acetamide-diphenyl ether, 2-maleimide-6-acetamide-pyridine, 4-maleimide-4'-acetamide-diphenylmethane, Np-phenylcarbonylphenyl-maleimide N-ethylmaleimide, N-2,6-xylylmaleimide, N-cyclohexylmaleimide, N-2,3-xylylmaleimide, xylylmaleimide, 2,6-xylenemaleimide, and 4,4'-bismaleimide-diphenylmethane.

[0038] There are no particular restrictions on the content of the photopolymerizable compound, and it can be appropriately selected depending on the purpose, but it is preferably 1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, relative to the total amount of the high refractive index curable composition. Furthermore, the mass ratio (A / B) of the metal alkoxide oligomer complex (A) to the photopolymerizable compound (B) is preferably 50 / 50 to 95 / 5, and more preferably 70 / 30 to 90 / 10.

[0039] <Polymerization initiator> The polymerization initiators are preferably photopolymerization initiators that generate radicals upon irradiation with visible light or ultraviolet light with a wavelength shorter than 450 nm. Examples include acetophenone-based polymerization initiators such as 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one; and acylphosphine oxide-based polymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. Examples of initiators include: benzoin-based polymerization initiators such as benzoin and 2,2-dimethoxy-1,2-diphenylethane-1-one; benzophenone-based polymerization initiators such as benzophenone, [4-(methylphenylthio)phenyl]phenylmethanone, 4-hydroxybenzophenone, 4-phenylbenzophenone, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone; and thioxanthone-based polymerization initiators such as 2-chlorothioxanthone and 2,4-diethylthioxanthone. These may be used individually or in combination of two or more types.

[0040] There are no particular restrictions on the content of the polymerization initiator, and it can be appropriately selected depending on the purpose, but it is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, per 100 parts by mass of the total of the metal alkoxide oligomer complex and the photopolymerizable compound.

[0041] <Other ingredients> The aforementioned other components are not particularly limited and can be appropriately selected depending on the purpose, and examples include solvents.

[0042] The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include alcohols such as methanol, ethanol, and isopropyl alcohol; ethers such as tetrahydrofuran and ethyl methyl ether; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, 1-methoxy-2-propanol (propylene glycol monomethyl ether, PGME), and propylene glycol monobutyl ether (PGB); methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate. Examples include alkylene glycol monoalkyl ether acetates such as acetate, propylene glycol methyl ether acetate (PGMEA), and 3-methoxybutyl-1-acetate; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl amyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; and esters such as ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-2-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethyl acetate, butyl acetate, methyl lactate, and ethyl lactate. These may be used individually or in combination of two or more types.

[0043] [viscosity] The viscosity of the high refractive index curable composition at 25°C is preferably 1000 mPa or less, more preferably 500 mPa or less, and even more preferably 300 mPa or less. If the viscosity of the high refractive index curable composition at 25°C is 1000 mPa or less, it is advantageous because it has low viscosity and excellent moldability, and high refractive index cured products can be manufactured using coating processes that require low viscosity, such as spin coaters. The viscosity can be measured using a rheometer (for example, device name: Rheometer AR-G2, manufactured by TA Instruments Co., Ltd.).

[0044] [Method for preparing a high refractive index curable composition] There are no particular limitations on the method for preparing the high refractive index curable composition, and it can be appropriately selected depending on the purpose. For example, a method of mixing the metal alkoxide oligomer complex, the inorganic nanoparticles, the photopolymerizable compound, the polymerization initiator, and other components as needed can be used.

[0045] (High refractive index cured material) The aforementioned high refractive index cured product is a cured product obtained by curing the high refractive index curable composition of this embodiment described above. There are no particular limitations on the method for curing the high refractive index curable composition, and a suitable method can be selected depending on the purpose. However, photopolymerization and thermal polymerization are preferred, and photopolymerization may be performed followed by thermal polymerization, or photopolymerization may be performed followed by thermal polymerization, or both may be performed simultaneously. Among these, photopolymerization following thermal polymerization is more preferred. Examples of the above-mentioned methods include: applying the high refractive index curable composition onto a substrate, allowing the sol-gel reaction of the metal alkoxide oligomer complex to proceed by heat treatment, and then photopolymerizing the photopolymerizable compound by light irradiation; applying the high refractive index curable composition onto a substrate, allowing the photopolymerizable compound to proceed by light irradiation, and then allowing the sol-gel reaction of the metal alkoxide oligomer complex to proceed by heat treatment; and filling the inside of a molding mold with the high refractive index curable composition and performing thermal polymerization by heat treatment and photopolymerization by light irradiation either sequentially or simultaneously. This makes it possible to manufacture the aforementioned high refractive index hardened material.

[0046] There are no particular limitations on the method of applying the high refractive index curable composition onto the substrate, and a suitable method can be selected depending on the purpose. Examples include a method of applying the high refractive index curable composition to the substrate with a uniform thickness over one surface using a bar coater or spin coater; or a method of applying the high refractive index curable composition to the substrate in a desired pattern shape using screen printing or the like.

[0047] Examples of the aforementioned heat treatment include temperatures between 180°C and 220°C for 30 minutes to 2 hours (for example, 200°C for 1 hour). Examples of the aforementioned light irradiation include light irradiation using high-pressure mercury lamps, metal halide lamps, and UV-LED irradiators. If the high refractive index curable composition contains a solvent, the solvent may be removed before curing by heating, reducing pressure, or other means as necessary.

[0048] [Refractive index] According to the high refractive index cured product of this embodiment, a high refractive index can be achieved, specifically, the refractive index n of the high refractive index cured product at a wavelength of 636 nm can be 1.70 or higher. The refractive index n of the high refractive index cured product at a wavelength of 636 nm is preferably 1.70 or higher, more preferably 1.72 or higher, even more preferably 1.74 or higher, and particularly preferably 1.80 or higher. The refractive index of the aforementioned high-refractive-index hardened material at a wavelength of 636 nm can be measured using a refractometer (for example, device name: Prism Coupler 2010 / M, manufactured by Metricon Japan Co., Ltd.).

[0049] [Glass transition temperature (Tg)] The high refractive index cured product of this embodiment has a high glass transition temperature and excellent heat resistance, specifically a Tg of 70°C or higher. The glass transition temperature (Tg) of the high refractive index hardened product is preferably 70°C or higher, more preferably 75°C or higher, even more preferably 80°C or higher, and particularly preferably a glass transition temperature so high that it cannot be measured by a differential scanning calorimetry device (at least 190°C or higher). The glass transition temperature (Tg) can be measured using a differential scanning calorimetry system (for example, the DSC 7000X, manufactured by Hitachi High-Tech Corporation).

[0050] The aforementioned high refractive index cured material is transparent and can have a total light transmittance of 90% or more.

[0051] There are no particular restrictions on the average thickness of the high refractive index cured material, and it can be appropriately selected depending on the purpose, but it is preferably 0.1 μm or more and 40 μm or less, and more preferably 1 μm or more and 10 μm or less. Here, the average thickness is the arithmetic mean of measurements taken at 10 arbitrary locations.

[0052] [Application] The high refractive index cured product of this embodiment can be used as a high refractive index curable composition capable of producing high refractive index cured products that achieve both high refractive index and thermal stability. Specifically, it can be used in optical components such as lenses, filters, optical fibers, mirrors, refractive optical elements, and diffractive optical elements; as well as in applications such as light-emitting device components, light-absorbing device components, and display device components.

[0053] The high refractive index cured material of this embodiment can be used for applications such as thinning optical lenses such as microlens arrays (see, for example, Japanese Patent Application Publication No. 2008-060121) and improving the light-gathering efficiency of optical transceivers (see, for example, Japanese Patent Application Publication No. 2004-096091). Furthermore, by creating a laminated structure that gradually eliminates the refractive index difference between air and the substrate, it can be suitably used for anti-reflective coatings on display devices such as solar cells and displays (see, for example, Japanese Patent Application Publication No. 2022-106002), contributing to the improvement of the performance of optical products. [Examples]

[0054] The following describes embodiments of the present invention, but the present invention is not limited in any way to these embodiments.

[0055] <Synthesis Example 1: Synthesis of Metal Alkoxide Oligomer Complexes> 6.5 g (11.8 mmol, calculated as titanium tetrabutoxide monomer) of Ti butoxide oligomer (trade name: PC-200, manufactured by Matsumoto Fine Chemical Co., Ltd.) as the metal alkoxide oligomer, and 2.6 g (11.8 mmol) of 2-acryloyloxyethyl succinic acid (trade name: A-SA, manufactured by Shin-Nakamura Chemical Co., Ltd.) as the ligand were added to a vial under inert conditions and stirred overnight at room temperature to obtain the metal alkoxide oligomer complex of Synthetic Product 1. The number-average molecular weight (Mn) of PC-200 was measured by gel permeation chromatography (GPC) and found to be 1753.

[0056] (Example 1) A high refractive index curable composition of Example 1 was prepared by blending 32 parts by mass of Synthesis 1, 8 parts by mass of 1-naphthalene methyl acrylate (trade name: NMT-A, manufactured by Kyoeisha Chemical Co., Ltd.), 200 parts by mass of titanium dioxide dispersion (trade name: OT-RA305K7-AC, manufactured by Nissan Chemical Corporation, solvent: MEK, solids content: 30% by mass, particle size by dynamic light scattering method: 10 nm to 30 nm) (60 parts by mass of solids and 140 parts by mass of solvent), 0.8 parts by mass of 2-hydroxy-2-methylpropiophenone (trade name: Omnirad1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 0.4 parts by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0057] Furthermore, using a wireless bar coater (device name: OSP-08, manufactured by OSG System Products Co., Ltd.), the prepared high refractive index curable composition was coated onto a glass slide (product name: S9111, manufactured by Matsunami Glass Industry Co., Ltd.) to achieve an average coating thickness of 8 μm. Next, to remove the solvent (MEK) contained in the titanium dioxide dispersion, a drying treatment was performed at 60°C for 30 minutes using a perfect oven (device name: PHH-102, manufactured by ESPEC Corporation). Following this, a heat treatment was performed at 200°C for 1 hour in the same apparatus to promote the sol-gel reaction of the metal alkoxide oligomer complex. After the heat treatment, a nitrogen purge was performed for 1 minute, and under a nitrogen atmosphere, an illuminance of 2 J / cm² was applied using a UV irradiation device (device name: iGrandage ECS-401GX, manufactured by iGraphics Co., Ltd.) equipped with a high-pressure mercury lamp (device name: H04-L41, manufactured by iGraphics Co., Ltd.). 2 A high refractive index cured material of Example 1 with an average thickness of 4 μm was fabricated by irradiation.

[0058] <Rating> The refractive index and glass transition temperature (Tg) of the fabricated high-refractive-index hardened material were measured and evaluated using the following procedure. The results are shown in Table 1.

[0059] <<Refractive index of high refractive index hardened material>> The refractive index of the high refractive index hardened material was measured at a wavelength of 636 nm using a refractometer (device name: Prism Coupler 2010 / M, manufactured by Metricon Japan Co., Ltd.) and evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: The refractive index at a wavelength of 636 nm is 1.80 or higher. ○: The refractive index at a wavelength of 636 nm is 1.70 or greater and less than 1.80. ×: The refractive index at a wavelength of 636 nm is less than 1.70.

[0060] <<Glass transition temperature (Tg) of high refractive index hardened material>> The Tg of the high refractive index hardened material was measured by peeling the material off the glass slide and using a differential scanning calorimetry system (device name: DSC 7000X, manufactured by Hitachi High-Tech Corporation), and evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: "ND", meaning it exhibits thermal stability that is immeasurable. ○: Tg is 70℃ or higher. ×: Tg is less than 70°C.

[0061] (Example 2) A high refractive index curable composition of Example 2 was prepared by blending 32 parts by mass of Synthesis 1, 8 parts by mass of dimethylol tricyclodecane diacrylate (trade name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 200 parts by mass of titanium dioxide dispersion (trade name: OT-RA305K7-AC, manufactured by Nissan Chemical Corporation, solvent: MEK, solids content: 30% by mass, particle size by dynamic light scattering method: 10 nm to 30 nm), 0.8 parts by mass of 2-hydroxy-2-methylpropiophenone (trade name: Omnirad 1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 0.4 parts by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0062] Next, a high-refractive-index cured product of Example 2 was prepared and evaluated in the same manner as in Example 1, except that the high-refractive-index curable composition of Example 2 was used. The results are shown in Table 1.

[0063] (Comparative Example 1) Comparative Example 1, a high refractive index curable composition, was prepared by blending 40 parts by mass of 1-naphthalene methyl acrylate (product name: Light Acrylate NMT-A, manufactured by Kyoeisha Chemical Co., Ltd.), 200 parts by mass of titanium dioxide dispersion (product name: OT-RA305K7-AC, manufactured by Nissan Chemical Corporation, solvent: MEK, solids content: 30% by mass, particle size by dynamic light scattering method: 10 nm to 30 nm), 0.8 parts by mass of 2-hydroxy-2-methylpropiophenone (product name: Omnirad 1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 0.4 parts by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (product name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0064] Next, a high-refractive-index cured product of Comparative Example 1 was prepared and evaluated in the same manner as in Example 1, except that the high-refractive-index curable composition of Comparative Example 1 was used. The results are shown in Table 2.

[0065] (Comparative Example 2) Comparative Example 2, a high refractive index curable composition, was prepared by blending 40 parts by mass of dimethylol tricyclodecane diacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 200 parts by mass of titanium dioxide dispersion (product name: OT-RA305K7-AC, manufactured by Nissan Chemical Corporation, solvent: MEK, solids content: 30% by mass, particle size by dynamic light scattering method: 10 nm to 30 nm), 0.8 parts by mass of 2-hydroxy-2-methylpropiophenone (product name: Omnirad1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 0.4 parts by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (product name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0066] Next, a high-refractive-index cured product of Comparative Example 2 was prepared and evaluated in the same manner as in Example 1, except that the high-refractive-index curable composition of Comparative Example 2 was used. The results are shown in Table 2.

[0067] (Comparative Example 3) Comparative Example 3, a high refractive index curable composition, was prepared by blending 100 parts by mass of 1-naphthalene methyl acrylate (trade name: Light Acrylate NMT-A, manufactured by Kyoeisha Chemical Co., Ltd.), 2 parts by mass of 2-hydroxy-2-methylpropiophenone (trade name: Omnirad 1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 1 part by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0068] Next, a high-refractive-index cured product of Comparative Example 3 was prepared and evaluated in the same manner as in Example 1, except that the high-refractive-index curable composition of Comparative Example 3 was used. The results are shown in Table 2.

[0069] (Comparative Example 4) Comparative Example 4, a high refractive index curable composition, was prepared by combining 100 parts by mass of dimethylol tricyclodecane diacrylate (trade name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 2 parts by mass of 2-hydroxy-2-methylpropiophenone (trade name: Omnirad 1173, manufactured by IGM Resins BV Co., Ltd.) as a polymerization initiator, and 1 part by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name: Omnirad TPO H, manufactured by IGM Resins BV Co., Ltd.).

[0070] Next, a high-refractive-index cured product of Comparative Example 4 was prepared and evaluated in the same manner as in Example 1, except that the high-refractive-index curable composition of Comparative Example 4 was used. The results are shown in Table 2.

[0071] (Comparative Example 5) Comparative Example 5, a high refractive index curable composition, was prepared using 333 parts by mass of titanium dioxide dispersion (product name: OT-RA305K7-AC, manufactured by Nissan Chemical Corporation, solvent: MEK, solids content: 30% by mass, particle size by dynamic light scattering method: 10 nm to 30 nm) (100 parts by mass of solids and 233 parts by mass of solvent).

[0072] Next, a high-refractive-index cured product of Comparative Example 5 was prepared in the same manner as in Example 1, except that the high-refractive-index curable composition of Comparative Example 5 was used. However, cracking of the film was observed after heat treatment, and film formation was not possible. The results are shown in Table 2.

[0073] [Table 1]

[0074] [Table 2]

[0075] In the high refractive index curable compositions of Examples 1 and 2, the resulting high refractive index cured products had a refractive index of 1.70 or higher and a Tg of 70°C or higher, demonstrating that it is possible to produce high refractive index cured products that achieve both high refractive index and thermal stability. In particular, Example 1, which used a naphthalene skeleton and a relatively high refractive index photopolymerizable compound, showed excellent refractive index of 1.80 or higher, while Example 2, which used a polyfunctional photopolymerizable compound, showed thermal stability so high that the Tg could not be measured.

[0076] On the other hand, the high refractive index curable compositions of Comparative Examples 1 to 5, which did not contain metal alkoxide oligomer complexes, could not achieve both a high refractive index and a high glass transition temperature. Furthermore, Comparative Examples 3 and 4, which did not contain inorganic nanoparticles, were found to have refractive indices significantly lower than 1.70. In addition, Comparative Example 5, which consisted of inorganic nanoparticles and a solvent, could not form a film.

Claims

1. A metal alkoxy oligomer complex represented by the following general formula (1), in which a ligand is coordinated to a metal alkoxy oligomer, Inorganic nanoparticles and Photopolymerizable compounds, It contains a polymerization initiator and The metal in the aforementioned metal alkoxide oligomer complex is a metal element from groups 4, 5, 13, 14, and 15. A high refractive index curable composition characterized in that the number average molecular weight of the metal alkoxy oligomer is 1000 or more. 【Chemistry 1】 In the general formula (1) above, M represents a metal, R independently represents an alkyl group having 1 to 18 carbon atoms, L represents a ligand, and n represents an integer of 1 or more.

2. The high refractive index curable composition according to claim 1, wherein the ligand content in the metal alkoxide oligomer complex is 0.1 moles or more and 3 moles or less per mole of metal in the metal alkoxide oligomer complex.

3. The high refractive index curable composition according to claim 1, wherein the particle size of the inorganic nanoparticles is 1 nm or more and 100 nm or less.

4. The high refractive index curable composition according to claim 1, wherein the content of the inorganic nanoparticles is 40% by mass or more and 80% by mass or less.

5. The high refractive index curable composition according to claim 1, wherein the content of the photopolymerizable compound is 1% by mass or more and 20% by mass or less.

6. The high refractive index curable composition according to claim 1, wherein the content of the metal alkoxide oligomer complex is 15% by mass or more and 55% by mass or less.

7. The high refractive index curable composition according to claim 1, wherein the mass ratio (A / B) of the metal alkoxy oligomer complex (A) to the photopolymerizable compound (B) is 50 / 50 to 90 / 10.

8. The high refractive index curable composition according to claim 1, wherein the metal of the metal alkoxide oligomer complex is titanium.

9. The high refractive index curable composition according to claim 1, wherein the inorganic nanoparticles are titanium oxide.

10. A high refractive index cured product characterized by being obtained by curing a high refractive index curable composition according to any one of claims 1 to 9.

11. The high refractive index cured product according to claim 10, wherein the refractive index n at a wavelength of 636 nm is 1.70 or more.

12. The high refractive index cured product according to claim 10, wherein the glass transition temperature measured by differential scanning calorimetry is 70°C or higher.

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