Method for producing particulate-dispersed polymeric composition, and particulate-dispersed polymeric composition produced by the method

Abstract

To provide a method for obtaining a particulate-dispersed polymeric composition, the method designed to disperse metal oxide particles at higher concentration.SOLUTION: A method for producing a particulate-dispersed polymeric composition includes a decompression step where a dispersion comprising metal oxide particulates (D) is subjected to vacuum drying treatment, to obtain dry powder (D1) of the metal oxide particulates (D).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a microparticle-dispersed polymerizable composition necessary for producing optical components such as optical resin lenses, optical waveguides, and light guide plates, a microparticle-dispersed polymerizable composition produced by the production method, a method for producing a microparticle-dispersed cured product using the microparticle-dispersed polymerizable composition, and a microparticle-dispersed cured product produced by the production method. [Background technology]

[0002] Inorganic glass has many excellent physical properties, such as excellent light transmission, and is used as an optical component in a wide range of fields. However, it has disadvantages such as being heavy and easily broken, and being difficult to process and to manufacture, and therefore optical resins have been actively developed as an alternative material to inorganic glass.

[0003] Examples of such optical resins include epoxy resins, unsaturated polyester resins, silicone resins, etc. There is a demand for general-purpose resin materials that have good light transmittance in a wide range or selectively in the range from visible light wavelengths to near infrared wavelengths, and that have excellent characteristics such as moldability, mass productivity, flexibility, toughness, and impact resistance compared to inorganic glass materials.

[0004] By imparting a high refractive index to such resin materials, it is expected that they can be used in a variety of applications, including materials for highly refractive optical components such as thin, lightweight optical lenses (eyeglass lenses, Fresnel lenses, pickup lenses in information recording devices such as CDs and DVDs, lenses for photographing devices such as digital cameras), optical prisms, optical waveguides, optical fibers, thin film moldings, optical adhesives, sealing materials for optical semiconductors, diffraction gratings, light guide plates, liquid crystal substrates, light reflectors, and anti-reflection materials.

[0005] Monomers containing sulfur elements are useful for increasing the refractive index. For example, there are resins (nd = about 1.60 to 1.66) obtained by thermally polymerizing a thiol compound and an isocyanate compound to form a thiourethane bond, and resins (nd = about 1.7) obtained by polymerizing and curing episulfide and epithiosulfide compounds. However, these are insufficient to achieve a higher refractive index of nd = 1.73 or more.

[0006] A method for increasing the refractive index to more than 1.73 includes a method of incorporating metal oxide fine particles into a resin. Metal oxide fine particles have a highly polar particle surface, so they are stably dispersed in highly polar solvents. On the other hand, metal oxide fine particles have low affinity with monomers containing sulfur, which are low polarity, and are difficult to mix with. Therefore, in this method, it is necessary to surface-modify the metal oxide fine particles using a polymer dispersant or organic acid in order to prevent the aggregation of the metal oxide fine particles and improve their compatibility with the monomer (for example, Patent Documents 1 and 2).

[0007] Another method for increasing the refractive index is to increase the concentration of metal oxide fine particles. However, in this case, in order to reduce the polarity of the particle surface and improve compatibility with the monomer, it is necessary to increase the amount of dispersant added. However, if too much dispersant is added, the surplus dispersant causes a problem that the refractive index is not sufficiently high. In view of these problems, there is a demand for a method for dispersing metal oxide fine particles at a higher concentration in order to obtain a fine particle-dispersed polymerizable composition. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2008-201634 A [Patent Document 2] Patent No. 5422393 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above problems, and provides a method for obtaining a microparticle-dispersed polymerizable composition useful for producing optical components such as optical resin lenses, optical waveguides, light guide plates, etc., and a method for producing a microparticle-dispersed cured product using the microparticle-dispersed polymerizable composition. The present invention also provides a microparticle-dispersed polymerizable composition and a microparticle-dispersed cured product having high light transmittance. [Means for solving the problem]

[0010] As a result of intensive research to solve the above problems, the present inventors have found that by carrying out a predetermined pretreatment before dispersing metal oxide fine particles in a specific sulfur-based dispersant, a fine particle-dispersed polymerizable composition that can contain metal oxide fine particles at a higher concentration can be obtained while suppressing the amount of sulfur-based dispersant added.Furthermore, they have found that a crosslinking reaction occurs between the sulfur-based dispersant and the polymerizable sulfur-based composition during the curing reaction, and a cured product with excellent light transmittance can be easily obtained.

[0011] That is, the present invention is as described below. [1] A method for producing a fine particle-dispersed polymerizable composition, comprising a decompression step of drying a dispersion containing metal oxide fine particles (D) under reduced pressure to obtain a dry powder (D1) of the metal oxide fine particles (D). [2] The method according to [1], wherein the solvent of the dispersion is a solvent (B) that is not uniformly mixed with the polymerizable sulfur-based composition (A). [3] The method according to [1] or [2], wherein the polymerizable sulfur-based composition (A) contains one or more compounds selected from the group consisting of compounds represented by the following structural formulas (1) to (8): [ka] (In the formula, m represents an integer of 0 to 4, and n represents an integer of 0 to 2.) [ka] (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) [ka] (In the formula, n represents an integer of 1 or 2.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) [ka] (In the formula, p and q each independently represent an integer of 1 to 3.) [ka] [ka] [4] The method according to [2] or [3], wherein the solvent (B) that is not uniformly mixed in the polymerizable sulfur-based composition (A) contains a lower alcohol. [5] A step of dissolving a sulfur-based dispersant (C) in an aprotic solvent (E) or a low-polarity solvent (F) to obtain a dissolved composition; a step of dispersing the dry powder (D1) of the metal oxide fine particles (D) obtained by the decompression step in the solution composition to obtain a fine particle-containing solution composition containing the metal oxide fine particles (D2) surface-modified with a sulfur-based dispersant (C); A step of mixing and stirring the fine particle-containing dissolved composition and a polymerizable sulfur-based composition (A) to obtain a dispersion composition; removing the aprotic solvent (E) or the low-polarity solvent (F) from the dispersion composition to obtain a fine particle-dispersed polymerizable composition containing the surface-modified metal oxide fine particles (D3) dispersed in the polymerizable sulfur-based composition (A); The method for producing a semiconductor device according to any one of [1] to [4], comprising the steps of: [6] The method according to any one of [1] to [5], wherein the content of the sulfur-based dispersant (C) is 15 to 75 parts by mass per 100 parts by mass of the polymerizable sulfur-based composition (A). [7] The method according to any one of [1] to [6], wherein the sulfur-based dispersant (C) contains two or more sulfur atoms or one or more episulfide groups in its molecular structure. [8] The method according to any one of [1] to [7], wherein the sulfur-based dispersant (C) is represented by the following general formula (9): K―N―M formula (9) (In the formula, K contains one or more hydrophilic partial structures selected from the group consisting of an alkoxysilyl group, a hydroxysilyl group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a catechol group, and a 3,4,5-trihydroxybenzoic acid group; M contains one or more lipophilic partial structures having a group containing a sulfur atom represented by the following general formulas (m1) to (m3); and N contains one or more partial structures selected from the group consisting of divalent linking groups represented by the following general formulas (n1) to (n3).) [ka] (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) [ka] (In the formula, n represents an integer of 1 or 2.) [ka] (In the formula, n represents an integer of 1 to 8.) [ka] (In the formula, X represents a carbon atom, an oxygen atom, a sulfur atom, or a nitrogen atom, m represents an integer of 0 to 7, and n represents an integer of 0 to 7.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 3.) [ka] (In the formula, n represents an integer of 1 to 3.) [9] The method according to any one of [1] to [8], wherein the metal oxide fine particles (D) contain one or more metal elements selected from the group consisting of zirconium, zinc, iron, copper, titanium, tin, indium, cerium, tantalum, niobium, tungsten, europium, and hafnium.

[10] The method according to any one of [1] to [9], wherein the aprotic solvent (E) comprises one or more selected from the group consisting of diethyl ether, tetrahydrofuran, dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and acetonitrile.

[11] The method according to any one of [1] to

[10] , wherein the low-polarity solvent (F) comprises one or more selected from the group consisting of diethyl ether, trichloromethane, hexane, benzene, toluene and o-xylene.

[12] A fine particle-dispersed polymerizable composition produced by the production method according to any one of [1] to

[11] .

[13] A method for producing a microparticle-dispersed cured product, comprising the step of producing a microparticle-dispersed polymerizable composition by the production method according to any one of [1] to

[11] .

[14] The method according to

[13] , further comprising a step of curing the fine particle-dispersed polymerizable composition by heat or active energy rays.

[15] A microparticle-dispersed cured material produced by the production method according to

[13] or

[14] . Effect of the Invention

[0012] According to the present invention, metal oxide microparticles that have been surface-modified with a sulfur-based dispersant are dispersed in a polymerizable sulfur-based composition at a higher concentration, and the obtained microparticle-dispersed polymerizable composition has excellent light transmittance and is easily moldable. The light transmittance of the microparticle-dispersed cured product is maintained even after curing, and therefore the composition can be developed into an imprint material used for producing optical elements, particularly thick light guide plates and thin diffraction gratings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described below. Note that the following is an example for explaining the present invention, and the present invention is not limited to the embodiment.

[0014] [Method of producing fine particle-dispersed polymerizable composition] 1. Decompression process The manufacturing method according to one embodiment of the present invention includes a decompression step of drying a dispersion containing metal oxide fine particles (D) under reduced pressure to obtain a dry powder (D1) of the metal oxide fine particles (D). In the manufacturing method according to one embodiment of the present invention, the solvent of the dispersion may be a solvent (B) that is not uniformly mixed with the polymerizable sulfur-based composition (A), or a solvent (B') that is uniformly mixed with the polymerizable sulfur-based composition (A). The solvent (B) and the solvent (B') will be described later. The apparatus used for the reduced pressure drying process is not particularly limited, and a known reduced pressure dryer can be used. For example, a distillation apparatus can be used as the reduced pressure dryer. The set temperature may be any temperature that can remove the solvent from the dispersion liquid, and is usually 30°C or higher, preferably 35°C or higher, more preferably 40°C or higher, and even more preferably 45°C or higher, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower. From the viewpoint of sufficiently removing the solvent of the dispersion liquid, the degree of vacuum is 0.5 to 50 Torr, preferably 0.5 to 40 Torr, more preferably 0.5 to 30 Torr, and even more preferably 0.5 to 20 Torr as a guide. The degree of vacuum can be measured, for example, using a commercially available vacuum gauge such as a rotary McLeod vacuum gauge. In addition, it is preferable to carry out the reduced pressure drying treatment while stirring the above-mentioned dispersion liquid while setting the degree of vacuum within the above range. The stirring method is not particularly limited, and for example, the stirring may be performed by rotating the container or by using a stirrer tip. The time for the reduced pressure drying treatment may be any temperature at which the solvent of the dispersion can be removed, and is usually 20 minutes or more, preferably 30 minutes or more, more preferably 35 minutes or more, and even more preferably 40 minutes or more, and is preferably 80 minutes or less, more preferably 70 minutes or less, and even more preferably 60 minutes or less. By adjusting the conditions of the reduced pressure drying treatment as described above, not only can the solvent of the dispersion be sufficiently removed, but also the viscosity of the resulting dry powder (D1) of metal oxide fine particles (D) can be reduced when dispersed in the polymerizable sulfur-based composition (A) described below, which is preferable from the viewpoint of moldability. The method for obtaining the dispersion is not particularly limited, and the metal oxide fine particles (D) can be dispersed in a solvent by a conventional method.

[0015] (Polymerizable sulfur composition (A)) The polymerizable sulfur-based composition (A) according to one embodiment of the present invention is a compound containing a sulfur atom in the molecule. Examples of the polymerizable sulfur-based composition (A) include epithio compounds ((thio)epoxy compounds) and thiol compounds. Furthermore, the polymerizable sulfur-based composition (A) may be a combination of a compound containing a sulfur atom in the molecule and an allyl compound or an isocyanate compound.

[0016] In a preferred embodiment of the present invention, the polymerizable sulfur-based composition (A) may contain at least one compound selected from the group consisting of compounds represented by the following structural formulas (1) to (8). [ka] (In the formula, m represents an integer of 0 to 4, and n represents an integer of 0 to 2.) [ka] (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) [ka] (In the formula, n represents an integer of 1 or 2.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) [ka] (In the formula, p and q each independently represent an integer of 1 to 3.) [ka] [ka]

[0017] (epithio compound) Examples of the epithio compound include bis(2,3-epithiopropyl)sulfide, bis(2,3-epithiopropyl)disulfide, bis(2,3-epithiopropylthio)methane, 1,2-bis(2,3-epithiopropylthio)ethane, 1,2-bis(2,3-epithiopropylthio)propane, 1,3-bis(2,3-epithiopropylthio)propane, 1,3-bis(2,3-epithiopropylthio)-2-methylpropane, 1,4-bis(2,3-epithiopropylthio)butane, and 1,4-bis(2,3-epithiopropylthio)-2-methylpropane. Methylbutane, 1,3-bis(2,3-epithiopropylthio)butane, 1,5-bis(2,3-epithiopropylthio)pentane, 1,5-bis(2,3-epithiopropylthio)-2-methylpentane, 1,5-bis(2,3-epithiopropylthio)-3-thiapentane, 1,6-bis(2,3-epithiopropylthio)hexane, 1,6-bis(2,3-epithiopropylthio)-2-methylhexane, 3,8-bis(2,3-epithiopropylthio)-3,6-dithiaoctane, 1,2,3-tris(2,3-epithiopropylthio)propane , 2,2-bis(2,3-epithiopropylthio)-1,3-bis(2,3-epithiopropylthiomethyl)propane, 2,2-bis(2,3-epithiopropylthiomethyl)-1-(2,3-epithiopropylthio)butane, 1,5-bis(2,3-epithiopropylthio)-2-(2,3-epithiopropylthiomethyl)-3-thiapentane, 1,5-bis(2,3-epithiopropylthio)-2,4-bis(2,3-epithiopropylthiomethyl)-3-thiapentane, 1-(2,3-epithiopropylthio)-2,2-bis(2,3-epithiopropylthiomethyl) 1,5,6-tris(2,3-epithiopropylthio)-4-(2,3-epithiopropylthiomethyl)-3-thiahexane, 1,8-bis(2,3-epithiopropylthio)-4-(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-4,5-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-4,4-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-2,5-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-2,4,5-tris(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,1,1-tris[{2-(2,3-epithiopropylthio)ethyl}thiomethyl]-2-(2,3-epithiopropylthio)ethane, 1,1,2,2-tetrakis[{2-(2,3-epithiopropylthio)ethyl} 2,3-epithiopropylthio compounds of aliphatic chains such as ethane, 1,11-bis(2,3-epithiopropylthio)-4,8-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane, 1,11-bis(2,3-epithiopropylthio)-4,7-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane, and 1,11-bis(2,3-epithiopropylthio)-5,7-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane; 2,3-epithiopropylthio compounds such as cycloaliphatic 2,3-epithiopropylthio compounds, such as 1,3-bis(2,3-epithiopropylthio)cyclohexane, 1,4-bis(2,3-epithiopropylthio)cyclohexane, 1,3-bis(2,3-epithiopropylthiomethyl)cyclohexane, 1,4-bis(2,3-epithiopropylthiomethyl)cyclohexane, 2,5-bis(2,3-epithiopropylthiomethyl)-1,4-dithiane, 2,5-bis[{2-(2,3-epithiopropylthio)ethyl}thiomethyl]-1,4-dithiane, and 2,5-bis(2,3-epithiopropylthiomethyl)-2,5-dimethyl-1,4-dithiane; aromatic 2,3-epithiopropylthio compounds such as 1,2-bis(2,3-epithiopropylthio)benzene, 1,3-bis(2,3-epithiopropylthio)benzene, 1,4-bis(2,3-epithiopropylthio)benzene, 1,2-bis(2,3-epithiopropylthiomethyl)benzene, 1,3-bis(2,3-epithiopropylthiomethyl)benzene, 1,4-bis(2,3-epithiopropylthiomethyl)benzene, bis{4-(2,3-epithiopropylthio)phenyl}methane, 2,2-bis{4-(2,3-epithiopropylthio)phenyl}propane, bis{4-(2,3-epithiopropylthio)phenyl}sulfide, bis{4-(2,3-epithiopropylthio)phenyl}sulfone, and 4,4'-bis(2,3-epithiopropylthio)biphenyl; Examples of the mercapto group-containing epithio compounds include 3-mercaptopropylene sulfide and 4-mercaptobutene sulfide. These may be used alone or in combination of two or more. The compounds are not limited to the exemplified compounds.

[0018] (Thiol compounds) Examples of the thiol compound include aliphatic thiol compounds, alicyclic thiol compounds, aromatic thiol compounds, and heterocycle-containing thiol compounds. More specifically, methanedithiol, 1,2-ethanedithiol, 1,2,3-propanetrithiol, 1,2-cyclohexanedithiol, bis(2-mercaptoethyl)ether, tetrakis(mercaptomethyl)methane, (2-mercaptoethyl)sulfide, diethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), and trimethylolethane tris(2-mercaptoacetate). , trimethylolethane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), bis(mercaptomethyl)sulfide, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)sulfide, bis(mercaptoethyl)disulfide, bis(mercaptopropyl)sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropylthio)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-bis (2-mercaptoethylthio)ethane, 1,2-bis(3-mercaptopropylthio)ethane, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-Trithiaundecane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane, and their thioglycolic acids and mercaptomethylsulfonates. Esters of captopropionic acid, hydroxymethyl sulfide bis(2-mercaptoacetate), hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide bis(2-mercaptoacetate), hydroxyethyl sulfide bis(3-mercaptopropionate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxmethyl disulfide bis(2-mercaptoacetate), hydroxmethyl disulfide bis(3-mercaptopropionate), hydroxmethyl disulfide bis(2-mercaptopropionate), hydrox ... Hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(2-mercaptoacetate), 2-mercaptoethyl ether bis(3-mercaptopropionate), thiodiglycolic acid bis(2-mercaptoethyl ester), thiodipropionic acid bis(2-mercaptoethyl ester), dithiodiglycolic acid bis(2-mercaptoethyl ester) aliphatic polythiol compounds such as dithiodipropionic acid bis(2-mercaptoethyl ester), 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, tris(mercaptomethylthio)methane, 1,2-bis[(2-mercaptoethyl)thio]3-mercaptopropane, and tris(mercaptoethylthio)methane; Aromatic polythiol compounds such as 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,3,5-trimercaptobenzene, 1,3,5-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyleneoxy)benzene, 1,3,5-tris(mercaptoethyleneoxy)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,5-naphthalenedithiol, and 2,6-naphthalenedithiol; Examples of the heterocyclic polythiol compounds include 2-methylamino-4,6-dithiol-sym-triazine, 3,4-thiophenedithiol, bismuthiol, 4,6-bis(mercaptomethylthio)-1,3-dithiane, and 2-(2,2-bis(mercaptomethylthio)ethyl)-1,3-dithietane. These may be used alone or in combination of two or more. The compounds are not limited to the exemplified compounds.

[0019] (Solvent (B)) The solvent (B) of one embodiment of the present invention is a solvent having a higher polarity than the polymerizable sulfur-based composition (A), which is not uniformly mixed with the polymerizable sulfur-based composition (A) and forms a different liquid phase. Suitable examples of such a solvent include lower alcohols. More preferably, the lower alcohols have 5 or less carbon atoms, and even more preferably, the lower alcohols have 3 or less carbon atoms. Specific examples of such a solvent include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, t-butyl alcohol, n-amyl alcohol, and sec-amyl alcohol. In one embodiment of the present invention, these solvents may be used alone or in combination of two or more. The above-mentioned solvent (B) may be a mixed solvent containing the above-mentioned lower alcohol and water. In this case, the content of water in the mixed solvent is not particularly limited, but may be 1 to 50% by mass, preferably 1 to 15% by mass, as a guideline.

[0020] (Solvent (B')) The solvent (B') of one embodiment of the present invention is a solvent that is uniformly mixed with the polymerizable sulfur-based composition (A) to form a single liquid phase and has the same polarity as the polymerizable sulfur-based composition (A). Examples of such solvents include glycol ethers such as 1-methoxy-2-propanol, and solvents similar to the aprotic solvent (E) or low polarity solvent (F) described below. In one embodiment of the present invention, these solvents may be used alone or in appropriate combination of two or more.

[0021] (Metal oxide fine particles (D)) The metal oxide fine particles (D) of one embodiment of the present invention contain one or more metal elements selected from the group consisting of zirconium, zinc, iron, copper, titanium, tin, indium, cerium, tantalum, niobium, tungsten, europium, and hafnium.

[0022] Examples of the metal oxide constituting the metal oxide fine particles (D) include single oxides such as titanium oxide (titania), aluminum oxide (alumina), zirconium oxide (zirconia), magnesium oxide (magnesia), and silicon oxide (silica); and composite oxides such as potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate, lithium titanate, lead zirconate titanate (PZT), and indium tin oxide (ITO). In one embodiment of the present invention, these metal oxides may be used alone or in combination as dispersoid particles. Among these, zirconium oxide is particularly preferred from the viewpoints of refractive index, translucency, and stability.

[0023] In a preferred embodiment of the present invention, the metal oxide fine particles (D) have a median diameter (D50), which is the particle diameter showing the 50% integrated value of the integrated distribution curve, of 20 nm or less, preferably 15 nm or less. By having such a particle diameter, it can contribute to high light transmittance of the obtained fine particle dispersion-type cured material. The metal oxide fine particles (D) preferably have a particle size D90, which is the 90% cumulative particle size in the particle size distribution, of 30 nm or less, and particularly preferably 25 nm or less, which can further increase the light transmittance of the fine particle-dispersed cured material. The D50 and D90 of the metal oxide fine particles (D) can be measured based on the volume-based particle size distribution in terms of the equivalent sphere diameter using a dynamic light scattering method.

[0024] The metal oxide fine particles (D) may be crystalline or amorphous, may be isotropic or anisotropic, or may be fibrous. The metal oxide fine particles (D) may be in the form of a general powder or a fine particle sol.

[0025] (Method for producing metal oxide fine particles (D)) The method for producing (preparation method) the metal oxide fine particles (D) used in the present invention is not particularly limited, and known methods can be suitably used. For example, representative production methods include two types of production methods: a top-down method in which coarse particles are mechanically crushed and refined; and a bottom-up method in which several unit particles are generated and then aggregated into a cluster state to form particles. Either method may be used for preparation. These production methods may be either a wet method or a dry method, but the dry method has a large pulverization limit particle size and is greatly affected by light scattering, so that the wet method is more preferable for optical applications. The medium used in these production methods may be aqueous, non-aqueous, or gas phase.

[0026] The bottom-up method may be either a physical method or a chemical method. A typical example of the physical method is a gas evaporation method in which bulk metal is evaporated in an inert gas and cooled and condensed by collision with the gas to generate nanoparticles. A typical example of the chemical method is a liquid phase reduction method (a method in which metal ions are reduced in the presence of a protective agent in a liquid phase and the generated zero-valent metal is stabilized in nanosize), a thermal decomposition method of a metal complex, and the like. More specific examples of the liquid phase reduction method include a chemical reduction method, an electrochemical reduction method, a photoreduction method, or a method in which a chemical reduction method and a photoirradiation method are combined.

[0027] When the metal oxide fine particles (D) are produced by employing the various methods or processes described above, a protective agent can be used to extract the metal oxide fine particles (D) from the medium used in the production process. Examples of the protective agent include a surface modifier that modifies the surface of the metal oxide fine particles (D) and a surface protective agent that protects the surface of the metal oxide fine particles (D). By covering the surface with the protective agent or impregnating the metal oxide fine particles (D) with the protective agent, the metal oxide fine particles (D) can be stably extracted from the medium.

[0028] 2. Obtaining a dissolved composition The production method according to one embodiment of the present invention includes a step of dissolving a sulfur-based dispersant (C) in an aprotic solvent (E) or a low-polarity solvent (F) to obtain a dissolved composition. The method of dissolution is not particularly limited, and the sulfur-based dispersant (C) can be dissolved in the aprotic solvent (E) or the low-polarity solvent (F) by a conventional method.

[0029] (Sulfur-based dispersant (C)) The sulfur-based dispersant (C) of one embodiment of the present invention contains two or more sulfur atoms or one or more episulfide groups in its molecular structure. In one embodiment of the present invention, the sulfur-based dispersant (C) has a hydrophilic group and a lipophilic group in its molecular structure, and the hydrophilic group contains one or more selected from the group consisting of an alkoxysilyl group, a hydroxysilyl group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a catechol group, and a 3,4,5-trihydroxybenzoic acid group, and the lipophilic group contains one or more selected from the group consisting of a sulfide group, a disulfide group, a thiol group, and a (thio)epoxy group.

[0030] In a preferred embodiment of the present invention, the sulfur-based dispersant (C) is represented by the following general formula (9): K―N―M formula (9) In formula (9), K contains one or more hydrophilic partial structures selected from the group consisting of an alkoxysilyl group, a hydroxysilyl group, a carboxyl group, a phosphate group, a phosphonic acid group, a phosphinic acid group, a catechol group, and a 3,4,5-trihydroxybenzoic acid group; M contains one or more lipophilic partial structures selected from the group consisting of groups containing a sulfur atom represented by the following general formulas (m1) to (m3); and N contains one or more partial structures selected from the group consisting of divalent linking groups represented by the following general formulas (n1) to (n3). In one embodiment of the present invention, the combination of M and N in formula (9) may be the following: That is, formula (9) may be K-(n1)-(m1), K-(n1)-(m2), K-(n1)-(m3), K-(n2)-(m1), K-(n2)-(m2), K-(n2)-(m3), K-(n3)-(m1), K-(n3)-(m2), K-(n3)-(m3). [ka] (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) [ka] (In the formula, n represents an integer of 1 or 2.) [ka] (In the formula, n represents an integer of 1 to 8.) [ka] (In the formula, X represents a carbon atom, an oxygen atom, a sulfur atom, or a nitrogen atom, m represents an integer of 0 to 7, and n represents an integer of 0 to 7.) [ka] (In the formula, R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 3.) [ka] (In the formula, n represents an integer of 1 to 3.)

[0031] In one embodiment of the present invention, the sulfur-based dispersant (C) may be used alone or in combination of two or more. Furthermore, the sulfur-based dispersant (C) may be used in combination with other silane coupling agents.

[0032] (Silane coupling agent) The silane coupling agent that can be used in combination with the sulfur-based dispersant (C) is not particularly limited, and examples thereof include silane coupling agents having a radical polymerization reactive functional group and other silane coupling agents.

[0033] Examples of the radical polymerization reactive silane coupling agent include vinyl group-containing silanes such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, and vinyltrimethoxysilane; and (meth)acryloyl group-containing silanes such as 3-methacryloxypropyltrimethoxysilane, with (meth)acryloyl group-containing silanes being preferred.

[0034] Other silane coupling agents are silane compounds that do not have functional groups that are reactive to radical polymerization.Other silane coupling agents include epoxy silanes such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropylmethyldiethoxysilane; amino silanes such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; mercapto silanes such as γ-mercaptopropyltrimethoxysilane; and haloalkyl group-containing silanes such as γ-chloropropylmethyldimethoxysilane and γ-chloropropylmethyldiethoxysilane.

[0035] (Aprotic Solvent (E)) The aprotic solvent (E) according to one embodiment of the present invention includes at least one selected from the group consisting of diethyl ether, tetrahydrofuran, dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and acetonitrile. Among these, tetrahydrofuran is more preferable as the aprotic solvent (E).

[0036] (Low polarity solvent (F)) The low polarity solvent (F) of one embodiment of the present invention includes at least one selected from the group consisting of diethyl ether, trichloromethane, hexane, benzene, toluene, and o-xylene. Among them, toluene is more preferable as the low polarity solvent (F).

[0037] 3. Step of obtaining a fine particle-containing dissolved composition A manufacturing method according to one embodiment of the present invention includes a step of dispersing the dry powder (D1) of metal oxide fine particles (D) obtained in the above-mentioned "1. Pressure reducing step" in the dissolved composition obtained in the above-mentioned "2. Step of obtaining a dissolved composition" to obtain a fine-particle-containing dissolved composition containing metal oxide fine particles (D2) surface-modified with a sulfur-based dispersant (C). The method for dispersing the dry powder (D1) in a dissolved composition containing the sulfur-based dispersant (C) and surface-modifying the dry powder (D1) with the sulfur-based dispersant (C) is not particularly limited, and can be performed by a method such as mixing and stirring. After the surface modification, the fine particle-containing solution composition may be allowed to stand. The time for which the composition is allowed to stand is not particularly limited, but may be, for example, 1 to 48 hours, and preferably 12 to 24 hours.

[0038] 4. Step of obtaining dispersion composition The manufacturing method according to one embodiment of the present invention includes a step of mixing and stirring the fine particle-containing solution composition obtained in the above "3. Step of obtaining fine particle-containing solution composition" with a polymerizable sulfur-based composition (A) to obtain a dispersion composition. This allows the metal oxide fine particles (D2) surface-modified with a sulfur-based dispersant (C) to be dispersed in the polymerizable sulfur-based composition (A). The method of mixing and stirring is not particularly limited, and any known method can be used as long as the metal oxide fine particles (D2) are dispersed in the polymerizable sulfur-based composition (A).

[0039] 5. Step of obtaining fine particle dispersion type polymerizable composition The manufacturing method according to one embodiment of the present invention includes a step of removing the aprotic solvent (E) or the low-polarity solvent (F) from the dispersion composition obtained in the above "4. Step of obtaining a dispersion composition" to obtain a microparticle-dispersed polymerizable composition containing the surface-modified metal oxide microparticles (D3) dispersed in the polymerizable sulfur-based composition (A). The polymerizable sulfur-based composition (A) in which the surface-modified metal oxide fine particles (D3) are dispersed is separated from the aprotic solvent (E) or the low-polarity solvent (F) and recovered to obtain a fine particle-dispersed polymerizable composition. The recovered fine particle-dispersed polymerizable composition may be further washed with an organic solvent. The method for removing the aprotic solvent (E) or the low polarity solvent (F) is not particularly limited, and may be, for example, a vacuum drying treatment. The vacuum drying method may be the same as that in the above "1. Pressure reduction step".

[0040] In the manufacturing method according to one embodiment of the present invention, the recovered fine particle-dispersed polymerizable composition may be additionally stirred or homogenized so that the surface-modified metal oxide fine particles (D3) are sufficiently dispersed in the polymerizable sulfur-based composition (A). For example, a roll mill such as a two-roll mill or a three-roll mill; a ball mill such as a ball mill or a vibration ball mill; a paint shaker; a bead mill such as a continuous disk-type bead mill or a continuous annular-type bead mill; a sand mill; a jet mill; or the like may be used, but is not limited thereto. Alternatively, the dispersion treatment may be performed in an ultrasonic bath.

[0041] The microparticle-dispersed polymerizable composition thus obtained is one in which an interaction is formed between the metal oxide microparticles (D) and the polymerizable sulfur-based composition (A) through the hydrophilic groups and lipophilic groups in the structure of the sulfur-based dispersant (C).

[0042] [Fine particle dispersion type polymerizable composition] The present invention also relates to a fine particle-dispersed polymerizable composition prepared through the above-mentioned steps. In a preferred embodiment of the present invention, the fine particle-dispersed polymerizable composition has a viscosity at 23° C. of 100,000 mPa s or less, more preferably 20,000 mPa s or less.

[0043] In one embodiment of the present invention, the combination of the main components used in the preparation of the fine particle-dispersed polymerizable composition, i.e., the polymerizable sulfur-based composition (A), the solvent (B) or the solvent (B'), the sulfur-based dispersant (C), the metal oxide fine particles (D), and the aprotic solvent (E) or the low-polarity solvent (F), may be in the following form. <1> Polymerizable sulfur-based composition (A): a compound having the structural formula (1), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m1) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <2> Polymerizable sulfur-based composition (A): a compound having the structural formula (1), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n3)-(m1) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <3> Polymerizable sulfur-based composition (A): a compound having the structural formula (1), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m3) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <4> Polymerizable sulfur-based composition (A): a compound having the structural formula (1), Solvent (B) or solvent (B'): ethanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m1) in the general formula (9), Metal oxide particles (D): Zinc oxide Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <5> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m1) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <6> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): ethanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m1) in the general formula (9), Metal oxide particles (D): zinc oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <7> Polymerizable sulfur-based composition (A): a compound having the structural formula (1), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m1) in the general formula (9), Metal oxide particles (D): titanium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene.

[0044] In addition, the combination of the polymerizable sulfur-based composition (A), the solvent (B) or the solvent (B'), the sulfur-based dispersant (C), the metal oxide fine particles (D), and the aprotic solvent (E) or the low-polarity solvent (F) may also have the following embodiments. <8> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n3)-(m1) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <9> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m3) in the general formula (9), Metal oxide particles (D): zirconium oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <10> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n3)-(m1) in the general formula (9), Metal oxide particles (D): zinc oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene. <11> Polymerizable sulfur-based composition (A): a compound having the structural formula (2), Solvent (B) or solvent (B'): methanol, methyl ethyl ketone, or 1-methoxy-2-propanol Sulfur-based dispersant (C): a compound having a structure represented by K-(n1)-(m3) in the general formula (9), Metal oxide particles (D): zinc oxide, Aprotic solvent (E) or less polar solvent (F): tetrahydrofuran or toluene.

[0045] In one embodiment of the present invention, the fine particle dispersion type polymerizable composition may contain components other than the above-mentioned components (A) to (F). Specific examples of the other components include various known additives such as surfactants, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, and antifoaming agents.

[0046] The fine particle-dispersed polymerizable composition of the present invention preferably contains a polymerization initiator, and more preferably contains at least one of a thermal polymerization initiator and a photopolymerization initiator. Examples of the polymerization initiator include an anionic polymerization initiator or a cationic polymerization initiator that generate ions, a thermal polymerization initiator that generates a polymerization initiating radical upon heating, and a photopolymerization initiator that generates a polymerization initiating radical upon irradiation with ultraviolet light. These polymerization initiators may be used alone or in combination of two or more. It is also preferable to further add a thermal polymerization promoter, a photosensitizer, a photopolymerization promoter, etc.

[0047] In the microparticle-dispersed polymerizable composition of the present invention, the blending amounts (contents or amounts added) of the above-mentioned components (A) to (F) are not particularly limited, and can be appropriately set in a suitable range depending on various conditions such as the type and physical properties of each component, the use of the microparticle-dispersed polymerizable composition, etc. Among them, the sulfur-based dispersant (C) is preferably blended within a predetermined range from the viewpoint of obtaining a microparticle-dispersed cured product with a high refractive index by dispersing the metal oxide fine particles (D) well, and from the viewpoint of avoiding high viscosity and improving production efficiency.

[0048] Specifically, the amount of the sulfur-based dispersant (C) is usually 5% by mass or more, preferably 7% by mass or more, more preferably 8% by mass or more, and even more preferably 9% by mass or more, when the total amount of the fine particle dispersion-type polymerizable composition is taken as 100% by mass. The upper limit of the amount of the sulfur-based dispersant (C) varies depending on the molecular structure of the dispersant and the type of the polymerizable sulfur-based composition (A), but as a guideline, it can be 50% by mass or less, 40% by mass or less, or 30% by mass or less, and preferably 20% by mass or less, 19% by mass or less, 18% by mass or less, 17% by mass or less, or 16% by mass or less.

[0049] The amount of the sulfur-based dispersant (C) is usually 10 to 80 parts by mass, preferably 15 to 75 parts by mass, more preferably 16 to 70 parts by mass, and even more preferably 17 to 60 parts by mass, per 100 parts by mass of the polymerizable sulfur-based composition (A), from the viewpoints of wettability of the dispersion medium and achieving a high refractive index of the microparticle-dispersed cured product.

[0050] The amount of the metal oxide fine particles (D) is preferably 5 to 90 mass%, more preferably 10 to 80 mass%, even more preferably 20 to 70 mass%, and particularly preferably 30 to 60 mass%, when the total amount of the fine particle-dispersed polymerizable composition is 100 mass%. Although it depends on the above-mentioned conditions, when the metal oxide fine particles (D) are within this range, the optical properties and physical properties of the obtained fine particle-dispersed cured product can be improved, and the combination with the sulfur-based dispersant (C) can also contribute to improving the surface smoothness.

[0051] The blending amount of the polymerizable sulfur-based composition (A) is preferably 1 to 95 mass%, more preferably 4 to 90 mass%, further preferably 10 to 70 mass%, and particularly preferably 20 to 60 mass%, when the total amount of the fine particle-dispersed polymerizable composition is 100 mass%. Although it depends on the above-mentioned various conditions, when the polymerizable sulfur-based composition (A) is blended within this range, when a film-like or layer-like microparticle-dispersed cured product (cured film or cured layer) is formed, the metal oxide microparticles (D) are well dispersed and good physical properties can be realized as a microparticle-dispersed cured product. In addition, the combination with the sulfur-based dispersant (C) can contribute to improving the surface smoothness of the cured product.

[0052] The amount of the solvent (B) or (B') is not particularly limited, and it is sufficient to disperse the metal oxide fine particles (D). The amount of the aprotic solvent (E) and the low polarity solvent (F) is also not particularly limited, and it is sufficient to dissolve the sulfur-based dispersant (C). The other components may be added within a range in which the desired function can be exhibited by adding the components.

[0053] [Method of manufacturing fine particle-dispersed cured product] The present invention also relates to a method for producing a microparticle-dispersed cured product, which comprises the steps of producing a microparticle-dispersed polymerizable composition by the above-mentioned steps. The method for producing a microparticle-dispersed cured product of the present invention further comprises a step of curing the above-mentioned microparticle-dispersed polymerizable composition by heat or active energy rays. In one aspect of the production method of the present invention, it is preferable to crosslink and cure the polymerizable component in the microparticle-dispersed polymerizable composition, the polymerizable component including one or more compounds selected from the group consisting of the compounds represented by the above general formulas (1) to (8).

[0054] [Fine particle dispersed cured product] The microparticle-dispersed cured material of one embodiment of the present invention can be obtained by curing the above-mentioned microparticle-dispersed polymerizable composition. Here, the term "microparticle-dispersed cured material" refers to a product obtained by crosslinking and curing the curable component of the microparticle-dispersed polymerizable composition of one embodiment of the present invention.

[0055] (Heat resistance of the cured product) In a preferred embodiment of the present invention, the microparticle-dispersed cured product has a certain level of heat resistance in order to be used as an optical material. An index showing heat resistance is the glass transition temperature of the cured product. The preferred heat resistance is determined by the type of substrate to which the microparticle-dispersed polymerizable composition is applied. For example, when the microparticle-dispersed polymerizable composition is used as an optical adhesive for sealing the gap between a pair of substrates between a resin sheet having a linear expansion coefficient close to that of the microparticle-dispersed polymerizable composition and a glass substrate, the glass transition temperature of the microparticle-dispersed cured product obtained by curing the microparticle-dispersed polymerizable composition of the present invention is preferably 30°C or higher, more preferably 70°C or higher. If the glass transition temperature of the microparticle-dispersed cured product is within the above range, there is little possibility of interfacial peeling between each substrate and the adhesive.

[0056] The resin sheet referred to here is preferably made of a resin that is highly transparent in the visible light region, and specific examples include polyethylene terephthalate, polymethyl methacrylate, polycarbonate, cyclic polyolefin (COC), polypropylene, polystyrene, polyvinyl chloride, transparent ABS resin, transparent nylon, transparent polyimide, polyvinyl alcohol, etc.

[0057] (Other physical properties of the cured product) The microparticle-dispersed cured material of one embodiment of the present invention has a d-line refractive index (nd) of 1.73 or more, a refractive index at 830 nm (n830) of 1.72 or more, a light transmittance at a wavelength of 800 nm and a light transmittance at a wavelength of 600 nm of 75.0% or more at a thickness of 0.25 mm. A preferred embodiment of the microparticle-dispersed cured product of the present invention has a d-line refractive index (nd) of 1.73 or more, a refractive index at 830 nm (n830) of 1.72 or more, a light transmittance at a wavelength of 800 nm and a light transmittance at a thickness of 0.25 mm of 79.0% or more, and a light transmittance at a wavelength of 600 nm of 77.0% or more. In each of the above embodiments, the Abbe number (vd) of the microparticle-dispersed cured material varies depending on the type of metal oxide microparticles (D) used, and the preferred range of the lower limit is, for example, 10.0 or more, 14.0 or more, 18.0 or more, 22.0 or more, 24.0 or more, 28.0 or more, 30.0 or more, 34.0 or more, 34.5 or more, or 35.0 or more. The preferred range of the upper limit is, for example, 50.0 or less, 40.0 or less, 30.0 or less, 25.0 or less, 20.0 or less, or 18.0 or less. EXAMPLES

[0058] The present invention will be specifically described below based on examples. However, the present invention is not limited to these examples. In the following description, "%" is based on mass unless otherwise specified.

[0059] (Synthesis of sulfur-based dispersant (C)) A 100 ml vial was charged with 73.7 g of 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (GST), a thiol compound, and 0.08 g of triphenylphosphine was added as a catalyst. After stirring at 50°C for 30 minutes, 8.1 g of 4-pentenoic acid was added. The mixture was further stirred at 80°C for 4 days. The end point of the reaction was determined by infrared absorption spectroscopy (IR) analysis, and the 1650-1630 cm region in the chemical structure of 4-pentenoic acid was determined. -1This was confirmed by the disappearance of absorption due to nearby alkenes. After the reaction, the mixture containing the product was purified using a medium pressure fractionation purification device to remove unreacted GST, and a compound represented by the following structural formula (10) having a hydrophilic structure and a lipophilic structure was obtained. [ka]

[0060] (viscosity measurement) The viscosity of the fine particle dispersion type polymerizable composition obtained by the method described below was measured at 23° C. using an electromagnetic spinning (EMS) viscometer (Kyoto Electronics Manufacturing Co., Ltd., EMS-1000S).

[0061] (Method of measuring optical properties of cured product) The optical properties of the microparticle-dispersed cured material obtained by the method described below were measured at 25°C. A UV-visible spectrophotometer (JASCO, V-630) was used to measure the transmittance. The transmittance was measured at wavelengths of 600 nm and 800 nm at a thickness of 0.25 mm. A Kalnew precision refractometer (Shimadzu Corporation, KPR-3000) was used to measure the refractive index. The refractive index nd and Abbe number νd of the d-line (wavelength 587.56 nm), and the refractive index n830 of LD830 (semiconductor laser, wavelength 823.92 nm) were measured.

[0062] Example 1 (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 5.60 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 6.72 g of tetrahydrofuran (THF) solvent and 0.61 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.71 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 1.0 mmol of dispersant per 1 g of particles, and containing zirconia particles at 42% by mass of the entire composition).

[0063] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.58% by mass of the fine particle dispersion type polymerizable composition obtained as Example 1 was mixed with 0.42% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred until homogeneous. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and then heated and cured using a dryer at 100°C for 300 minutes and 140°C for 180 minutes. The cured film sandwiched between two plates of glass and visible on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0064] Example 2 (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 5.60 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 6.72 g of tetrahydrofuran (THF) solvent and 0.36 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.96 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 0.60 mmol of dispersant per 1 g of particles, and containing zirconia particles at 42 mass% of the entire composition).

[0065] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.50% by mass of the fine particle dispersion type polymerizable composition obtained as Example 2 was mixed with 0.50% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred until homogeneous. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and then heated and cured using a dryer at 100°C for 180 minutes and 140°C for 300 minutes. The cured film sandwiched between two plates of glass and visible on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0066] Example 3 (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 6.67 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 8.00 g of tetrahydrofuran (THF) solvent and 0.65 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.35 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 0.90 mmol of dispersant per 1 g of particles, and containing zirconia particles at 50% by mass of the entire composition).

[0067] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.65% by mass of the fine particle dispersion type polymerizable composition obtained as Example 3 was mixed with 0.35% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred until homogeneous. The mixture was sandwiched between release-treated plate-shaped glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and then heated and cured using a dryer at 100°C for 180 minutes and 140°C for 420 minutes. The cured film sandwiched between two plates of glass and visible on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0068] Example 4 (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 6.67 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 8.00 g of tetrahydrofuran (THF) solvent and 0.58 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.42 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 0.80 mmol of dispersant per 1 g of particles, and containing zirconia particles at 50% by mass of the entire composition).

[0069] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.65% by mass of the fine particle dispersion type polymerizable composition obtained as Example 4 was mixed with 0.35% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred until homogeneous. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and then heated and cured using a dryer at 100°C for 180 minutes and 140°C for 420 minutes. The cured film sandwiched between two plates of glass and visible on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0070] Example 5 (Method of producing fine particle dispersion type hardened material: episulfide type, photocuring) To 97.90% by mass of the fine particle dispersion type polymerizable composition obtained as Example 4, 1.05% by mass of tetrabutylammonium=butyltrinaphthyl borate as a photocuring agent and 1.05% by mass of 4-benzoyl-4'-methyldiphenyl sulfide as a sensitizer were added, and the mixture was stirred until it became uniform. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and 395 nm LED light (CCS Inc., HLDL-120V9-NWPSC, 500 mW / cm 2) for 15 minutes. Then, the film was heat-treated at 140°C for 120 minutes using a dryer. The cured film sandwiched between two glass plates was peeled off from the glass plates and subjected to evaluation of the optical properties.

[0071] (Reference example 1) (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 5.60 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 6.72 g of tetrahydrofuran (THF) solvent and 1.00 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.32 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 1.65 mmol of dispersant per gram of particles, and containing zirconia particles at 42% by mass of the entire composition).

[0072] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.68% by mass of the fine particle dispersion type polymerizable composition obtained as Reference Example 1 was mixed with 0.32% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred until homogeneous. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm spacer, and then heated and cured using a dryer at 100°C for 180 minutes and 140°C for 300 minutes. The cured film sandwiched between two plates of glass and visible on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0073] (Reference example 2) (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 6.67 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 8.00 g of tetrahydrofuran (THF) solvent and 0.87 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 1.13 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 1.20 mmol of dispersant per 1 g of particles, and containing zirconia particles at 50% by mass of the entire composition).

[0074] (Method of producing fine particle dispersion type hardened material: episulfide type, heat curing) 99.73% by mass of the fine particle dispersion type polymerizable composition obtained as Reference Example 2 was mixed with 0.27% by mass of tetra-n-butylphosphonium bromide as a heat curing agent, and stirred at 45°C for 60 minutes until it became uniform. The mixture was sandwiched between release-treated plate glass (Matsunami Glass Industry, model number S9213) together with a 0.25 mm thick spacer, and then heated and cured using a dryer at 100°C for 180 minutes and 140°C for 420 minutes. The cured film that was sandwiched between two plates of glass and could be visually confirmed on the transmission side was peeled off from the glass plates and used for evaluation of optical properties.

[0075] (Reference example 3) (Surface modification method and method for preparing fine particle-dispersed polymerizable composition: episulfide type) 5.60 g of a zirconia particle methanol dispersion (Sakai Chemical Industry, zirconia particles 30% by mass, SZR-M, D50 = 4.0 nm, D90 = 6.7 nm) was prepared in a 20 mL vial together with a magnetic stirrer. Using a distillation apparatus, the temperature was kept at 45°C and the vacuum level was kept at 10 Torr or less (confirmed with a rotary McLeod vacuum gauge), and the methanol solvent was removed over 45 minutes while rotating the stirrer. Next, 6.72 g of tetrahydrofuran (THF) solvent and 0.24 g of the sulfur-based dispersant represented by the above structural formula (10) were prepared in a glass bottle. After stirring at room temperature for 15 minutes to prepare a dissolved composition, the dissolved composition was added to a 20 mL vial from which methanol had been removed, and mixed and stirred at room temperature for 16 hours using a magnetic stirrer. Then, 2.08 g of a (thio)epoxy compound in which n=0 in the above structural formula (1) was added to the vial, and the mixture was mixed and stirred at room temperature for 15 minutes. The THF solvent was removed over 60 minutes using a distillation apparatus at 45° C. and a vacuum of 10 Torr or less (as confirmed by a rotary McLeod vacuum gauge). Through the above steps, a fine particle-dispersed polymerizable composition consisting of surface-modified zirconia particles and a polymerizable sulfur-based composition was obtained (containing 0.40 mmol of dispersant per 1 g of particles, and containing zirconia particles at 42 mass% of the entire composition).

[0076] The microparticle-dispersed polymerizable composition obtained as Reference Example 3 had no fluidity and high viscosity, and could not be taken out of a 20 mL vial at room temperature even after 60 minutes at 45° C. Therefore, it was not possible to measure the viscosity of the microparticle-dispersed polymerizable composition or the optical properties of the microparticle-dispersed cured product.

[0077] [Table 1]

[0078] From the results in Table 1, it can be said that the microparticle-dispersed polymerizable composition produced by the production method of the present invention and the microparticle-dispersed cured product produced using the microparticle-dispersed polymerizable composition are excellent optical materials and are useful for optical elements such as diffraction gratings, optical waveguides, optical fibers, lenses, and filters.

Claims

1. A method for producing a particulate-dispersed polymerizable composition, comprising a reduced-pressure step of obtaining a dry powder (D1) of metal oxide fine particles (D) by subjecting a dispersion liquid containing the metal oxide fine particles (D) to reduced-pressure drying treatment.

2. The production method according to claim 1, wherein the solvent of the dispersion liquid is a solvent (B) that is not uniformly mixed with the polymerizable sulfur-based composition (A).

3. The production method according to claim 1, wherein the polymerizable sulfur-based composition (A) contains one or more selected from the group consisting of compounds represented by the following structural formulas (1) to (8). 【Chemical 1】 (In the formula, m represents an integer of 0 to 4, and n represents an integer of 0 to 2.) [Chemical 2] (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) [Chemical Formula 3] (In the formula, n represents an integer of 1 or 2.) 【Chemical Formula 4】 (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) 【Chemical Formula 5】 (In the formula, R represents a hydrogen atom or a methyl group, and p represents an integer of 1 to 2.) 【Chemical Formula 6】 (In the formula, p and q each independently represent an integer of 1 to 3.) 【Chemical Formula 7】 【Chemical 8】

4. The production method according to claim 2, wherein the solvent (B) that is not uniformly mixed with the polymerizable sulfur-based composition (A) contains a lower alcohol.

5. A step of dissolving a sulfur-based dispersant (C) in an aprotic solvent (E) or a low-polarity solvent (F) to obtain a dissolved composition; A step of dispersing the dry powder (D1) of the metal oxide fine particles (D) obtained by the reduced-pressure step in the dissolved composition to obtain a particulate-containing dissolved composition containing the metal oxide fine particles (D2) surface-modified with the sulfur-based dispersant (C); A step of mixing and stirring the particulate-containing dissolved composition and the polymerizable sulfur-based composition (A) to obtain a dispersed composition; A step of removing the aprotic solvent (E) or the low-polarity solvent (F) from the dispersed composition to obtain a particulate-dispersed polymerizable composition containing the surface-modified metal oxide fine particles (D3) dispersed in the polymerizable sulfur-based composition (A); The production method according to claim 1, comprising the above steps.

6. The production method according to claim 1, wherein the content of the sulfur-based dispersant (C) is 15 to 75 parts by mass with respect to 100 parts by mass of the polymerizable sulfur-based composition (A).

7. The production method according to claim 1, wherein the sulfur-based dispersant (C) contains two or more sulfur atoms or one or more episulfide groups in its molecular structure.

8. The production method according to claim 1, wherein the sulfur-based dispersant (C) is represented by the following general formula (9). K―N―M Formula (9) (In the formula, K contains one or more hydrophilic partial structures selected from the group consisting of an alkoxysilyl group, a hydroxysilyl group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a catechol group, and a 3,4,5-trihydroxybenzoic acid group; M contains one or more lipophilic partial structures having a group containing a sulfur atom represented by the following general formulas (m1) to (m3); N contains one or more partial structures selected from the group consisting of divalent linking groups represented by the following general formulas (n1) to (n3).) 【Chemical Formula 9】 (In the formula, p represents an integer of 2 to 4, and Xp and Zp each independently represent a hydrogen atom or a methylthiol group.) 【Chemical Formula 10】 (In the formula, n represents an integer of 1 or 2.) 【Chemical Formula 11】 (In the formula, n represents an integer of 1 to 8.) 【Chemical 12】 (In the formula, X represents a carbon atom, an oxygen atom, a sulfur atom, or a nitrogen atom; m represents an integer of 0 to 7; and n represents an integer of 0 to 7.) 【Chemical 13】 (In the formula, R represents a hydrogen atom or a methyl group; and n represents an integer of 1 to 3.) 【Chemical 14】 (In the formula, n represents an integer of 1 to 3.)

9. The production method according to claim 1, wherein the metal oxide fine particles (D) contain one or more metal elements selected from the group consisting of zirconium, zinc, iron, copper, titanium, tin, indium, cerium, tantalum, niobium, tungsten, europium, and hafnium.

10. The production method according to claim 5, wherein the aprotic solvent (E) contains one or more selected from the group consisting of diethyl ether, tetrahydrofuran, dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and acetonitrile.

11. The production method according to claim 5, wherein the low-polarity solvent (F) contains one or more selected from the group consisting of diethyl ether, trichloromethane, hexane, benzene, toluene, and o-xylene.

12. A fine particle-dispersed polymerizable composition produced by the production method according to any one of claims 1 to 11.

13. A production method of a fine particle-dispersed cured product, including a step of producing a fine particle-dispersed polymerizable composition by the production method according to any one of claims 1 to 11.

14. The production method according to claim 13, further including a step of curing the fine particle-dispersed polymerizable composition by heat or active energy rays.

15. A fine particle-dispersed cured product produced by the production method according to claim 13.

Images