Zirconium oxide nanoparticle-containing composition and cured product thereof

Abstract

To provide a zirconium oxide particle-containing composition improved in dispersibility of zirconium oxide nanoparticles.SOLUTION: The composition of the present invention contains zirconium oxide nanoparticles and a crosslinkable compound represented by the following formula (1). In the formula (1), Z represents an n-valent linking group; and n represents an integer of 2 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to compositions and cured products thereof, and more particularly to compositions containing zirconium oxide nanoparticles and cured products thereof. [Background technology]

[0002] Fine particle-containing compositions, such as resin compositions and curable compositions containing various functional fine particles, can contribute to the enhancement of functionality and performance of various materials, including optical materials, electronic component materials, magnetic recording materials, catalytic materials, ultraviolet absorbing materials, and dental materials, depending on the function of the fine particles. Among these, zirconium oxide particles, which exhibit a high refractive index, are attracting considerable attention, and in order to fully utilize the functionality of zirconium oxide, it is important that the zirconium oxide is well dispersed in the zirconium oxide-containing composition. For example, Patent Document 1 discloses a technique for using benzyl acrylate as a monomer, dispersing zirconium oxide in benzyl acrylate, obtaining a cured film of the dispersion, and improving the refractive index of the cured film. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-66021 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, in order to meet the demand for even higher performance, it has become desirable for zirconium oxide nanoparticles to be more highly dispersed in compositions containing monomers and the like. Therefore, the object of the present invention is to provide a zirconium oxide particle-containing composition in which the dispersibility of zirconium oxide nanoparticles is improved. [Means for solving the problem]

[0005] The present invention, which has achieved the above objectives, is as follows. [1] A composition characterized by comprising zirconium oxide nanoparticles and a crosslinkable compound represented by the following formula (1). [ka] In equation (1), Z represents an n-valence linking group, and n represents an integer greater than or equal to 2. [2] The composition according to [1], wherein Z in formula (1) has an ether bond. [3] The composition according to [1] or [2], wherein Z in formula (1) is a residue obtained by removing a hydrogen atom from the hydroxyl group of a polyhydric alcohol. A cured product of any of the compositions described in [4], [1], or [3]. [Effects of the Invention]

[0006] The composition of the present invention, comprising a specific crosslinkable compound and zirconium oxide nanoparticles, can have a low viscosity. [Modes for carrying out the invention]

[0007] 1.Crosslinkable compound The crosslinkable compound in the present invention is a compound represented by the following formula (1), that is, a compound having two or more α-allyloxymethylacryloyl groups (hereinafter referred to as AMA groups) in the same molecule.

[0008] [ka]

[0009] In formula (1) above, Z represents an n-valent linking group, and n represents an integer of 2 or more. In formula (1) above, n is not particularly limited as long as it is 2 or more, but it is preferably 2 to 100, and more preferably 2 to 50, in terms of ease of synthesis and storage stability. When the crosslinkable compound is used in applications requiring low viscosity, such as reactive diluents, it is even more preferably 2 to 10, and most preferably 2 to 6.

[0010] In the above formula (1), Z is not particularly limited as long as it is a linking group capable of forming two or more covalent bonds with the carbonyl group of the AMA group, that is, a covalent linking group with a valence of 2 or higher. Z may be a linking group with a valence of 2 or higher bonded via only one atom, or may be a linking group with a valence of 2 or higher bonded via two or more atoms. From the viewpoints of ease of synthesis and chemical stability, Z is preferably a linking group with a valence of 2 or higher bonded via two or more atoms.

[0011] When Z is a linking group with a valence of 2 or higher bonded via only one atom, Z is not particularly limited, and examples thereof include linking groups containing Group 16 atoms of the periodic table such as an oxygen atom and a sulfur atom; Group 15 atoms of the periodic table such as a nitrogen atom and a phosphorus atom; and Group 14 atoms of the periodic table such as a carbon atom, a silicon atom and a germanium atom. Specific examples thereof include structures as shown in the following structural formula group (3).

[0012]

Chemical Formula

[0013] In the formula, R and R' each represent a hydrogen atom or an organic group, and R and R' may be the same or different. The organic group is only required to be a monovalent organic group capable of bonding to the above atom, and is preferably a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

[0014] When Z is a linking group with a valence of 2 or higher bonded via two or more atoms, Z may have a low-molecular structure or a high-molecular structure. The terms low-molecular structure and low-molecular skeleton described below generally mean a structure or skeleton having no repeating units derived from monomer units, and conversely, the terms high-molecular structure and high-molecular skeleton described below generally mean a structure or skeleton having repeating units derived from monomer units. As a general technical term, a high-molecular compound means a compound or polymer having a molecular weight of 1000 or more, but in the present invention, the terms "low-molecular" and "high-molecular" are not distinguished or limited by such molecular weight.

[0015] The above Z may include at least a skeletal portion Q, and may also include a divalent linking group X that links an AMA group to Q, a linking group Y with two or more valencies that links two or more skeletal portions Q, and a monovalent substituent W that is directly bonded to the skeletal portion Q. In an n-valence linking group Z, n hydrogen atoms in the skeletal portion Q may be substituted with AMA groups or X, and the remaining hydrogen atoms may be substituted with Y and / or W.

[0016] Taking a crosslinkable compound having two AMA groups as an example, the crosslinkable compound of the present invention can be represented, for example, as shown in the following group of structural formulas (4). For simplicity, the AMA group is represented by A in the formulas, and the structural examples are only some examples and are not limited to these.

[0017] [ka]

[0018] In the formula, Q n , X n , Y n , W n (where n is an integer greater than or equal to 1.) represents the nth Q, X, Y, and W when there are n of each, and these may be the same or different.

[0019] Furthermore, in the case of a crosslinkable compound having two AMA groups, where Q is a cyclohexane skeleton, X is an oxygen atom, Y is a urethane bond, and W is a fluorine atom, specific examples include the compounds shown in the following structural formula group (5). Note that the compounds shown in structural formula group (5) are only some examples of such compounds and do not represent all examples. As shown in structural formula group (5), two of the hydrogen atoms of the cyclohexane skeleton may be substituted with AMA groups or X, and the remaining hydrogen atoms may be substituted with Y and / or W.

[0020] [ka]

[0021] As described above, Z consists of a skeletal portion Q and may also include a divalent linking group X that bonds to the AMA group, a linking group Y with two or more skeletal portions Q that bonds to two or more skeletal portions Q, and a monovalent substituent W that is directly bonded to the skeletal portion Q. If Z consists of two or more skeletal portions Q, the Qs may be directly bonded to each other without the linking group Y. Z may consist only of Q, that is, the AMA group may be directly bonded to Q, but for ease of synthesis, availability of raw materials, and chemical stability, it is preferable that Z consists of at least Q and X, that is, that the AMA group is bonded to Q via X, and further, it is preferable that the carbonyl group of the AMA group and X are bonded by a heteroatom. That is, it is preferable that Z is an n-valent linking group that bonds to the AMA group via a heteroatom, and it is preferable that the heteroatom is an oxygen atom. In other words, it is preferable that at least one of the ends of Z that bonds to the AMA group is -O-, and it is more preferable that all ends are -O-. Y and W may be appropriately selected according to the synthesis method and the required performance for the application. Furthermore, Z may be composed of two or more types of Q, X, Y, and W.

[0022] Specific examples of Q, X, Y, and W are given below, but are not limited to these. In the case of Q below, its structure is exemplified as a compound, but when it is a component of Z, it is in a form in which two or more hydrogen atoms in the compound form of Q are substituted by atoms or groups of atoms (i.e., AMA groups, or Q, X, Y, W) bonded to Q. Note that although Q, X, Y, and W are components of Z, it is not limited to the fact that Z is composed of compounds that can constitute Q, X, Y, and W, respectively. When Z is structurally decomposed into Q, X, Y, and W, the structures of those components and the forms in which those structures are represented as compounds are exemplified below.

[0023] The above-mentioned skeletal portion Q only needs to have two or more atoms forming the skeleton, and to which an AMA group and / or X can be bonded. If the structure of Q is shown as a compound, it is not particularly limited as long as it is a compound in which two or more atoms forming the skeleton, and two or more hydrogen atoms (i.e., hydrogen atoms that can be substituted with an AMA group and / or X) are bonded to the atoms forming the skeleton, and such hydrogen atoms can become the skeletal portion of Z in a form in which they are substituted with an AMA group and / or X. For example, the structure of skeletal portion Q can be shown as a compound as follows.

[0024] Saturated hydrocarbon structures such as ethane, propane, n-butane, isobutane, n-pentane, isopentane, 2,2-dimethylpropane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, and eicosane; Hydrocarbon monoene structures such as ethylene, propene, butene, pentene, hexene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, and eicosene; Hydrocarbon diene structures such as allene, butadiene, pentadiene, hexadiene, nonadiene, decadiene, undecadien, dodecadien, tridecadien, tetradecadien, pentadecadien, hexadecadien, heptadecadien, octadecadien, nonadecadien, and eicosadiene; Hydrocarbon polyene structures such as heptadecatriene, heptadecatetraene, octadecatriene, and octadecatetraene; Acetylene-based structures such as acetylene, methylacetylene, and hexadiyne; Alicyclic structures of cyclopentane, cyclopentene, cyclopentadiene, cyclohexane, cyclohexene, cyclohexadiene, norbornane, norbornene, norbornadiene, cyclodecane, dicyclopentadiene, adamantane, cyclopentanone, cyclohexanone, cyclooctanone, and various compounds shown in the following chemical formula group (6);

[0025] [ka]

[0026] Aromatic hydrocarbon structures such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, triphenylene, pyrene, perylene, biphenyl, and various compounds shown in the following chemical formula group (7);

[0027] [ka]

[0028] Ethylene oxide, ethyleneimine, oxetane, tetrahydrofuran, tetrahydropyran, dihydrofuran, dihydropyran, pyran, dioxane, pyrrolidine, piperidine, piperazine, morpholine, γ-lactone, δ-lactone, ε-caprolactone, γ-lactam, δ-lacram, ε-caprolactam, oxazoline, succinic anhydride, maleic anhydride, succinimide, maleimide, glutaric anhydride, glutarimide, and heterocyclic structures of various compounds shown in the following chemical formula group (8) (especially non-aromatic heterocyclic structures);

[0029] [ka]

[0030] Examples of low molecular weight structures include pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, isoxazole, isothiazole, pyridine, pyridazine, pyrazine, benzofuran, indole, benzimidazole, benzoxazole, benzothiazole, quinoline, quinoxaline, acridine, pyrimidine, triazine, carbazole, phenothiazine, quinacridone, xanthene, cyanuric acid, phthalic anhydride, phthalimide, and various compounds shown in the following chemical formula group (9); and heteroaromatic structures.

[0031] [ka]

[0032] Furthermore, polyethylene skeletons represented by the following formula (10) obtained by (co)polymerization of acyclic ethylenic compounds such as ethylene, propylene, styrene, methyl acrylate, methyl methacrylate, and vinyl acetate;

[0033] [ka]

[0034] Various main chain ring structural skeletons shown in the following group of structural formulas (11) obtained by (co)polymerization of unsaturated cyclic compounds such as cycloalkenes including norbornene, unsaturated acid anhydrides including maleic anhydride, and maleimides including phenylmaleimide;

[0035] [ka]

[0036] Examples of polymer skeletons include: polyethylene-main-chain ring structure copolymer skeletons obtained by copolymerization of the above-mentioned acyclic ethylenic compounds and unsaturated cyclic compounds; polyether skeletons having ether links in the main chain obtained by dehydration condensation (co)polymerization of diols or ring-opening (co)polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and tetrahydrofuran; polyester skeletons having ester links in the main chain obtained by dehydration condensation (co)polymerization of dicarboxylic acids and diols or ring-opening (co)polymerization of cyclic lactones; polyamide skeletons having amide links in the main chain obtained by dehydration condensation (co)polymerization of dicarboxylic acids and diamines or ring-opening (co)polymerization of cyclic lactams; polysiloxane skeletons having siloxane links in the main chain obtained by dealcoholization condensation (co)polymerization of dialkyldialkoxysilanes or ring-opening (co)polymerization of cyclic siloxanes; and polyurethane skeletons having a urethane structure in the main chain obtained by reactions of diisocyanates and diols.

[0037] The above-mentioned skeletal portion Q can be appropriately set depending on the application in which the crosslinkable compound is used. However, a low molecular weight skeleton is preferred for applications requiring low viscosity, such as reactive diluents, while a polymer skeleton is preferred for applications requiring film-forming properties, such as binder resins in paints and resist materials. The appropriate skeleton should be selected according to the application. Among the low molecular weight skeletons, it is preferable that at least one structure is selected from the group consisting of saturated hydrocarbon structures, alicyclic structures, and aromatic hydrocarbon structures, based on the availability of raw materials and chemical stability. Among the polymer skeletons, it is preferable that at least one skeleton is selected from the group consisting of polyethylene skeletons, polyethylene-main chain structure copolymer skeletons, and polyether skeletons, based on the ease of synthesis and chemical stability.

[0038] The above X is not particularly limited as long as it is a divalent linking group, but for example, the bonds shown in the following group of structural formulas (12) can be cited (for example, if we represent it as AXQ and show the atoms or groups of atoms of X, it will be as follows).

[0039] [ka]

[0040] In the formula, R and R' represent, either the same or different, a hydrogen atom, an optionally substituted C1-C30 alkyl group, or an optionally substituted C1-C30 aryl group. Among these, from the standpoint of ease of synthesis and chemical stability, X is preferably an oxygen atom-containing group, a sulfur atom-containing group, a monosubstituted nitrogen atom (i.e., -NR-)-

[0041] The above Y is not particularly limited as long as it is a linking group with two or more valent values, but examples include the bonds shown in the following group of structural formulas (13).

[0042] [ka]

[0043] In the formula, R and R' represent, either the same or different, a hydrogen atom, an optionally substituted C1-C30 alkyl group, or an optionally substituted C1-C30 aryl group. Among these, ether bonds, thioether bonds, bonds with divalent to tetravalent carbon atoms, ketotic bonds, ester bonds, amide bonds, urethane bonds, or silicate ester bonds are preferred due to their ease of synthesis and chemical stability, with ether bonds, bonds with divalent to tetravalent carbon atoms, ester bonds, amide bonds, or urethane bonds being particularly preferred. If two or more Y atoms are present in Z, there may be one or more Y atoms.

[0044] The above W can be any monovalent substituent that can bond to the skeletal portion Q, and is not particularly limited. To give an example of the above W, Atoms of Group 17 of the periodic table, such as fluorine, chlorine, bromine, and iodine; Saturated hydrocarbon groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-amyl, s-amyl, t-amyl, n-hexyl, s-hexyl, n-heptyl, n-octyl, s-octyl, t-octyl, 2-ethylhexyl, capryl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, cetyl, heptadecyl, stearyl, nonadecyl, eicosyl, ceryl, and mericyl; Unsaturated hydrocarbon groups such as vinyl, allyl, methallyl, clotyl, and propagyl; Alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, tricyclodecanyl, isobornyl, adamantyl, and dicyclopentadienyl; Aromatic hydrocarbon groups such as phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, 4-t-butylphenyl, naphthyl, and anthranyl; Alkoxy groups such as hydroxyl, methoxy, ethoxy, propoxy, butoxy, phenoxy, and naphthoxy groups; amino groups such as amino groups, methylamino groups, dimethylamino groups, methylethylamino groups, and methylphenylamino groups; Examples include (meth)acryloyl groups, mercapto groups, thioalkoxy groups, cyano groups, nitro groups, isocyanate groups, thiocyanate groups, quaternary ammonium bases of amino groups, carboxyl groups or their salts, sulfonic acid groups or their salts, sulfinic acid groups or their salts, phosphate groups or their salts, etc. These should be used according to the application.

[0045] The above Z is preferably configured as (i) or (ii) below, with configuration (i) being more preferred. In (i) and (ii) below, as described above, Q is in a form in which the hydrogen atoms in the compound form of Q are replaced by X, Y, and W bonded to Q. (i) Z is composed of n (n is 2 or more) Qs linked in a linear chain, two Xs that bond the Qs at both ends to the AMA group, and (n-1) Ys that bond adjacent Qs together, with Q being a saturated hydrocarbon structure and X and Y being ether bonds. (ii) Z is composed of m (m is 1 or more) Qs linked in a linear chain, p (p is 2 or more) Xs that bond Qs to AMA groups, and (m-1) Ys that, if m is 2 or more, bond adjacent Qs together, with Q being a saturated hydrocarbon structure and X and Y being ether bonds.

[0046] In the embodiment of (i) above, it is more preferable that at least one of the following conditions is met: (i-1) Q is a saturated hydrocarbon having 2 to 6 carbon atoms; (i-2) n is 2 or more and 10 or less (preferably 2 or more and 6 or less); and (i-3) Y is bonded by substituting a hydrogen atom of a secondary carbon in Q. It is even more preferable that any two of these requirements are met simultaneously, and it is most preferable that all three of these requirements are met.

[0047] In the embodiment of (ii) above, it is more preferable that at least one of the following conditions is met: (ii-1) Q is a saturated hydrocarbon having 4 to 10 carbon atoms (preferably a branched saturated hydrocarbon having 4 to 10 carbon atoms); (ii-2) m is 1 to 3 (preferably 1); and (iii) p is 3 or more (preferably 3 or more and 5 or less, more preferably 3). It is even more preferable that any two of these requirements are met simultaneously, and it is most preferable that all three of these requirements are met.

[0048] Furthermore, it is preferable that at least one of X and Y is an ether linkage, that is, that Z has an ether linkage, and more preferably that Z is a residue obtained by removing a hydrogen atom from the hydroxyl group of a polyhydric alcohol. The polyhydric alcohol is: Glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, diethylene glycol, tripropylene glycol, neopentyl glycol, and pinacol; Trihydric alcohols such as glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 2-methyl-1,2,3-propanetriol, 1,2,3-pentanetriol, 1,2,4-pentanetriol, 1,3,5-pentanetriol, 2,3,4-pentanetriol, 2-methyl-2,3,4-butanetriol, 2-methyl-2,3,4-butanetriol, trimethylolethane, 2,3,4-hexanetriol, 2-ethyl-1,2,3-butanetriol, trimethylolpropane, 4-propyl-3,4,5-heptanetriol, 2,4-dimethyl-2,3,4-pentanetriol, and tris(2-hydroxyethyl) isocyanurate; Tetrahydric alcohols such as erythritol, pentaerythritol, diglycerin, and sorbitan; Pentahydric alcohols such as adonitol, arabitol, xylitol, and triglycerin; Hexahydric alcohols such as dipentaerythritol, sorbitol, mannitol, iditol, inositol, dalucitol, talose, and allose; These are some examples.

[0049] For a method of producing the above crosslinkable compound, refer to the descriptions in paragraphs

[0057] to

[0084] of Japanese Patent Publication No. 2011-74068.

[0050] 2. Zirconium oxide nanoparticles The average primary particle diameter of zirconium oxide nanoparticles is preferably 50 nm or less, more preferably 30 nm or less, even more preferably 20 nm or less, preferably 1 nm or more, and more preferably 5 nm or more. When the average primary particle diameter of zirconium oxide nanoparticles is within the above range, the transparency of the zirconium oxide nanoparticle-containing composition is easily enhanced. The average primary particle diameter can be determined by observing the zirconium oxide nanoparticles under magnification using a transmission electron microscope (TEM), field emission transmission electron microscope (FE-TEM), field emission scanning electron microscope (FE-SEM), etc., randomly selecting 100 particles, measuring their length along their long axis, and calculating the arithmetic mean.

[0051] Furthermore, if the zirconium oxide nanoparticles are coated with a coating agent described later, it is preferable that the coated zirconium oxide nanoparticles satisfy the average primary particle diameter described above.

[0052] The crystal structure of zirconium oxide nanoparticles can be determined by X-ray diffraction, and is preferably cubic, tetragonal, or monoclinic, although multiple crystal structures may be present. Note that X-ray diffraction measurements make it difficult to distinguish between cubic and tetragonal zirconium oxide nanoparticles, and even if cubic structures are present, their proportion is counted as that of tetragonal structures. The refractive index is... From the viewpoint of improvement, it is preferable that 50% or more of the overall crystal structure is tetragonal and / or cubic. Furthermore, the ratio of the total tetragonal and cubic crystals to monoclinic crystals ((tetragonal + cubic) / monoclinic) is preferably 1.0 or more, more preferably 1.1 or more, and may also be 3 or less, or 2 or less.

[0053] The crystallite size of the zirconium oxide nanoparticles is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less, and is usually 1 nm or more. The smaller the crystallite size, the higher the light transmittance of the composition containing the zirconium oxide nanoparticles. The crystallite size can be determined by X-ray diffraction.

[0054] Zirconium oxide nanoparticles can be obtained by hydrothermal synthesis of zirconium oxide precursors such as zirconium hydroxide, chloride, oxychloride, acetate, oxyacetic acid, oxynitrate, sulfate, carbonate, and alkoxide.

[0055] 3. Coating agent In the present invention, zirconium oxide nanoparticles are preferably coated with a coating agent, and more preferably the coating agent contains a secondary carboxylic acid. The zirconium oxide nanoparticles coated with a secondary carboxylic acid have good affinity with the crosslinkable compound, allowing for good dispersion even at high concentrations of zirconium oxide nanoparticles, achieving low viscosity, and preferably high transparency and a good refractive index. Furthermore, by allowing for high concentrations of zirconium oxide nanoparticles, a high refractive index can be achieved in the cured monomer containing zirconium oxide nanoparticles.

[0056] The amount of coating agent is preferably 0.5% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and may also be 25% by mass or less, or 20% by mass or less, based on 100% by mass of the coated zirconium oxide nanoparticles.

[0057] 3-1.2 secondary carboxylic acids A secondary carboxylic acid is a carboxylic acid in which the carbon atom bonded to the carboxyl group (-COOH group) is a secondary carbon.

[0058] The secondary carboxylic acid is preferably a monocarboxylic acid, and the number of carbon atoms of the secondary carboxylic acid is 4 or more, preferably 5 or more, more preferably 6 or more, even more preferably 7 or more, and may also be 30 or less, 20 or less, or 16 or less. Examples of secondary carboxylic acids include isobutyric acid, 2-methylbutyric acid, 2-ethylbutyric acid, 2-ethylhexanoic acid, 2-methylvaleric acid, 2-methylhexanoic acid, 2-methylheptanoic acid, 2-propylbutyric acid, 2-hexylvaleric acid, 2-hexyldecanoic acid, 2-heptylundecanoic acid, and 2-methylhexadecanoic acid. Preferably, it is 2-ethylhexanoic acid, 2-methylvaleric acid, 2-methylhexanoic acid, 2-methylheptanoic acid, 2-propylbutyric acid, 2-hexylvaleric acid, or 2-hexyldecanoic acid, more preferably 2-ethylhexanoic acid or 2-hexyldecanoic acid, and most preferably 2-ethylhexanoic acid.

[0059] The amount of secondary carboxylic acid per 100% by mass of coated zirconium oxide particles is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, even more preferably 2% by mass or more, and also preferably 8% by mass or less, more preferably 6% by mass or less, and even more preferably 4% by mass or less.

[0060] Furthermore, the proportion of secondary carboxylic acid in 100% by mass of the coating agent is preferably 5% by mass or more, more preferably 10% by mass or more, and may also be 100% by mass, but may also be 25% by mass or less, or 20% by mass or less.

[0061] 3-2. Carboxylic acids other than secondary carboxylic acids The coating agent may contain carboxylic acid compounds other than secondary carboxylic acids. The carboxylic acid compound refers to a compound containing one or more carboxyl groups (-COOH groups), and may be a compound having one carboxyl group in one molecule, or a compound having two or more carboxyl groups.

[0062] Other carboxylic acid compounds besides secondary carboxylic acids include: Linear saturated aliphatic carboxylic acids, including linear saturated aliphatic monocarboxylic acids such as butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, palmitic acid, and stearic acid, and linear saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid; Branched-chain saturated aliphatic carboxylic acids, which are primary carboxylic acids such as isovaleric acid, 3,3-dimethylbutyric acid, 3,3-diethylbutyric acid, 3-methylvaleric acid, isononanoic acid, 4-methylvaleric acid, and 4-methyloctanoic acid; Branched-chain saturated aliphatic carboxylic acids, such as pivalic acid, 2,2-dimethylbutyrate, 2,2-dimethylvaleric acid, 2,2-diethylbutyrate, 2,2-dimethylhexanoic acid, and neodecanoic acid, which are tertiary carboxylic acids; Alicyclic hydrocarbon group-containing carboxylic acids, including monocarboxylic acids containing alicyclic hydrocarbon groups such as naphthenic acid, and dicarboxylic acids containing alicyclic hydrocarbon groups such as cyclohexanedicarboxylic acid; Linear unsaturated aliphatic carboxylic acids such as acrylic acid, methacrylic acid, oleic acid, linoleic acid, and linolenic acid; Ether-containing carboxylic acids such as methoxyacetic acid, ethoxyacetic acid, 3-ethoxypropionic acid, 2-methoxyethoxyacetic acid, and 2-methoxyethoxyethoxyacetic acid; Hydroxy group-containing carboxylic acids, including lactic acid, hydroxystearic acid, glycolic acid, DL-lactic acid, 2-hydroxyisobutyric acid, dimethylolpropionic acid, hydroxypivalic acid, 3-hydroxypropionic acid, DL-2-hydroxybutyric acid, DL-3-hydroxybutyric acid, 2-hydroxy-2-methylbutyric acid, β-hydroxyisovaleric acid, 2,2-bis(hydroxymethyl)butyric acid, 4-hydroxycyclohexanecarboxylic acid, (o-,m-,p-)hydroxybenzoic acid, and hydroxy group-containing polycarboxylic acids such as malic acid and citric acid; Carbonyl group-containing carboxylic acids such as pyruvate, levulinic acid, 2-oxovaleric acid, β-methyllevulinic acid, and α-methyllevulinic acid; Aromatic carboxylic acids include aromatic monocarboxylic acids such as benzoic acid, and aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, and trimellitic acid; (Meth)acryloyl group-containing carboxylic acids such as 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl phthalic acid, and 2-methacryloyloxyethyl phthalic acid; Sulfide bond-containing carboxylic acids such as phenylthioacetic acid; Amino group-containing carboxylic acids, including amino group-containing monocarboxylic acids such as glycine, alanine, 2-methylalanine, cysteine, serine, threonine, valine, leucine, isoleucine, methionine, and lysine, and amino group-containing dicarboxylic acids such as aspartic acid and glutamic acid; Cyano group-containing carboxylic acids such as cyanoacetic acid; Examples include heterocyclic compounds substituted with carboxyl groups such as proline.

[0063] Among these, carboxylic acids containing a (meth)acryloyl group are preferred.

[0064] The amount of carboxylic acid compounds other than secondary carboxylic acids relative to the amount of secondary carboxylic acids is preferably 1.0 or more, more preferably 2.0 or more, even more preferably 3.0 or more, and preferably 5.0 or less, and more preferably 4.0 or less, in molar ratio.

[0065] 3-3. Others The coating agent may contain secondary carboxylic acids, carboxylic acid compounds other than secondary carboxylic acids, as well as phosphate esters, silane coupling agents, surfactants, titanium coupling agents, and the like.

[0066] As the phosphate ester, commercially available phosphate esters can be used as appropriate, such as DISPERBYK-110, 111, 180 (manufactured by Bic Chemie Japan Co., Ltd.) and Prysurf A208B, A208F, A208N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0067] Examples of silane coupling agents include (meth)acryloxy group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

[0068] Examples of surfactants include ionic surfactants such as anionic surfactants, cationic surfactants, and amphoteric surfactants, as well as nonionic surfactants.

[0069] Examples of titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl dimethacrylate isostearoyl titanate, isopropyl tri(dodecyl)benzenesulfonyl titanate, neopentyl(diallyl)oxy-tri(dioctyl) phosphate titanate, and neopentyl(diallyl)oxy-trineododecanoyl titanate.

[0070] Zirconium oxide nanoparticles coated with a coating agent containing a secondary carboxylic acid can be obtained, for example, by hydrothermally synthesizing a salt of a secondary carboxylic acid and zirconium to obtain zirconium oxide nanoparticles coated with a secondary carboxylic acid, and if necessary, by preparing a dispersion of the zirconium oxide nanoparticles coated with a secondary carboxylic acid in an organic solvent, and then adding and mixing other coating agents to the dispersion.

[0071] 4. Composition As described above, the composition of the present invention contains zirconium oxide nanoparticles and a crosslinking compound. The composition of the present invention has low viscosity, and in particular, it can reduce viscosity when the refractive index is made equivalent to that of other zirconium oxide nanoparticle-containing compositions.

[0072] The content of zirconium oxide nanoparticles relative to 100% by mass of solid components in the composition is preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more. The upper limit is not particularly limited, but may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. The solid components refer to components excluding the solvent, and reactive compounds are not included in the solvent. Furthermore, if the zirconium oxide nanoparticles are coated with a coating agent, it is preferable that the content of coated zirconium oxide nanoparticles falls within the above range.

[0073] The content of the crosslinkable compound in the composition relative to 100% by mass of the solid components is preferably 3% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and may be 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0074] The refractive index, total light transmittance, and HAZE of the composition can be measured according to the methods of the examples described later, and their values ​​are as follows. The refractive index of the composition is preferably 1.570 or higher, more preferably 1.580 or higher, and there is no particular upper limit, but it may be, for example, 1.710 or lower. The total light transmittance of the composition is preferably 85% or higher, more preferably 86% or higher, and even more preferably 87% or higher. There is no particular upper limit, but it may be, for example, 92% or lower. The HAZE content of the composition is preferably 3.0% or less, more preferably 2.8% or less, and even more preferably 2.7% or less. The lower limit is not particularly limited, but may be, for example, 0.8% or more.

[0075] Furthermore, the composition of the present invention may also contain other polymerizable monomers, solvents, polymers (resins), or other additives other than the crosslinkable compound described above.

[0076] 4-1. Other polymerizable monomers Other polymerizable monomers include monofunctional monomers having one polymerizable double bond or crosslinkable monomers having two or more polymerizable double bonds, and one or more of these can be used in combination.

[0077] Examples of monofunctional monomers include (meth)acrylic acid esters, such as alkyl (meth)acrylates including methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; styrene monomers such as styrene, 4-tert-butylstyrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, p-chlorostyrene, and p-chloromethylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid; and hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxy-2-hydroxypropyl (meth)acrylate, and 3-phenoxy-2-hydroxypropyl (meth)acrylate.

[0078] Furthermore, monofunctional monomers include compounds that contain two or more aromatic rings in one molecule and have one polymerizable double bond. The aromatic rings may be aromatic hydrocarbon rings or aromatic heterocycles, and are preferably aromatic hydrocarbon rings such as benzene rings and naphthalene rings. Specific examples of such compounds include biphenylmethyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, ethoxylated phenylphenol (meth)acrylate, ethoxylated cumylphenol (meth)acrylate, 2-(1-naphthyloxy)ethyl (meth)acrylate, 2-(2-naphthyloxy)ethyl (meth)acrylate, naphthyloxypolyethylene glycol (meth)acrylate, and N-vinylcarbazole.

[0079] Examples of crosslinkable monomers include alkylene glycols such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and tetramethylene glycol di(meth)acrylate. Examples include crosslinkable (meth)acrylic acid esters, such as poly(meth)acrylate; polyfunctional styrene monomers such as divinylbenzene; polyfunctional allyl ester monomers such as diallyl phthalate, diallyl isophthalate, triallyl cyanurate, and triallyl isocyanurate; 2-(2-vinyloxyethoxy)ethyl (meth)acrylate; urethane acrylate oligomers (for example, the Shiko® series (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), the CN series (manufactured by Sartomer Co., Ltd.), the Unidick® series (manufactured by DIC Corporation), the Kayarad® UX series (manufactured by Nippon Kayaku Co., Ltd.), etc.).

[0080] If the composition of the present invention contains other polymerizable monomers other than the crosslinkable compound, the crosslinkable compound can be used as a reactive diluent. In such cases, the amount of the crosslinkable compound relative to 100% by mass of the solid components in the composition can be 3% by mass or more and 10% by mass or less (preferably 8% by mass or less).

[0081] 4-2. Solvent Suitable solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 1-methoxy-2-propanol, and ethylene glycol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate and propyl acetate; ethers such as ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, and propylene glycol monomethyl ether; modified ethers such as propylene glycol monomethyl ether acetate (especially ether-modified and / or ester-modified alkylene glycols); hydrocarbons such as benzene, toluene, xylene, ethylbenzene, hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, and mineral spirits; halogenated hydrocarbons such as dichloromethane and chloroform; amides such as dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; water; and oils such as mineral oil, vegetable oil, wax oil, and silicone oil. These may be used individually or in combination of two or more. From a handling standpoint, solvents with a boiling point of approximately 40°C or higher and 250°C or lower at atmospheric pressure (1013 hPa) are preferred.

[0082] 4-3. Polymers (resins) As polymers (resins), one or more types can be used, and examples include polyamides such as 6-nylon, 66-nylon, and 12-nylon; polyimides; polyurethanes; polyolefins such as polyethylene and polypropylene; polyesters such as PET, PBT, and PEN; polyvinyl chlorides; polyvinylidene chlorides; polyvinyl acetates; polystyrenes; (meth)acrylic resin polymers; ABS resins; fluororesins; phenol-formaldehyde resins; phenolic resins such as cresol-formaldehyde resins; epoxy resins; urea resins; melamine resins; amino resins such as guanamine resins; polyvinyl butyral resins; polyurethane resins; ethylene-vinyl acetate copolymer resins; ethylene-(meth)acrylic acid ester copolymer resins, and other soft and hard resins.

[0083] 4-4. Other Additives Other additives include radical polymerization initiators, surfactants, curing agents, curing accelerators, colorants, internal mold release agents, coupling agents, reactive diluents, plasticizers, stabilizers, flame retardant aids, crosslinking agents, low shrinkage agents, polymerization inhibitors, antioxidants, UV absorbers, defoaming agents, leveling agents, thixotropes, and thickeners.

[0084] The radical polymerization initiators mentioned above include thermal radical initiators that generate radicals upon heating and photoradical initiators that generate radicals upon irradiation with active energy rays. One or more of the radical initiators commonly used can be used.

[0085] Suitable thermal radical initiators include organic peroxide-based initiators and azo-based initiators. Suitable photoradical initiators include alkylphenone compounds, benzophenone compounds, benzoin compounds, thioxanthone compounds, halomethylated triazine compounds, halomethylated oxadiazole compounds, biimidazole compounds, oxime ester compounds, titanocene compounds, benzoic acid ester compounds, and acridine compounds. All of these can be referenced from polymerization initiators disclosed in Japanese Patent Application Publication No. 2011-74068.

[0086] In 100% by mass of the composition of the present invention, the content of components other than zirconium oxide particles, the crosslinkable compound, the other polymerizable monomers described above, and the solvent is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 0 to 3% by mass.

[0087] 5.Cured product The present invention also includes cured products of compositions containing zirconium oxide nanoparticles and the crosslinkable compound. Articles made from the cured products are suitably used for optical applications. The compositions of the present invention have good curability, meaning they can be cured with low irradiation energy, and the resulting cured products also have excellent thermal stability. The shape of the cured product is not particularly limited, and the thickness is not particularly limited, but examples include plate-like, sheet-like, film-like, and fibrous forms. In particular, the thickness when the cured product is plate-like, sheet-like, or film-like, and the diameter when it is fibrous, is preferably 0.01 μm to 5 mm, more preferably 0.1 μm to 500 μm, and more preferably 0.1 μm to 100 μm.

[0088] When the composition of the present invention is coated to a thickness of approximately 0.05 μm to 0.3 μm, the radiation level is 9000 mJ / cm². 2 The composition can be cured with the following ultraviolet irradiation dose. The ultraviolet irradiation dose is more preferably 8000 mJ / cm². 2 The following, and more preferably 7500 mJ / cm² 2 The lower limit is not particularly limited, but for example, 5000 mJ / cm². 2 It is to that extent.

[0089] The temperature at which the weight loss rate of the cured product is 5% when the heat resistance is measured in the manner shown in the examples described below is, for example, 334°C or higher, more preferably 335°C or higher, and there is no particular upper limit, but for example it is 340°C.

[0090] The refractive index of the cured product can be, for example, 1.590 or higher, more preferably 1.600 or higher, and even more preferably 1.610 or higher. There is no particular upper limit, but for example, 1.650. The aforementioned refractive index values ​​are preferably those when the thickness or fiber diameter of the cured product is 0.1 μm to 1 μm.

[0091] The composition of the present invention, due to the excellent dispersibility of zirconium oxide nanoparticles, is suitable for applications such as resists, optical applications, coatings, and adhesives. It is particularly suitable for optical lenses, adhesives for optical films, adhesives for optical films, resin compositions for nanoimprints, microlens arrays, anti-reflective layers used in transparent electrodes, anti-reflective films and anti-reflective agents, surface coatings for optical lenses, organic EL light extraction layers, various hard coating materials, planarization films for TFTs, overcoats for color filters, various protective films such as anti-reflective films, and optical materials such as optical filters, insulating films for touch sensors, insulating films for TFTs, photospacers for color filters, and protective films for touch panels. In particular, the coated metal oxide nanoparticles of the present invention have outstanding dispersibility, high refractive index, high hardness, and high stability, making them preferable for use in optical lenses, surface coatings for optical lenses, various hard coating materials, insulating films for touch sensors, insulating films for TFTs, and protective films for touch panels. [Examples]

[0092] The present invention will be described in more detail below with reference to examples. The present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit described below, and all such modifications are included within the technical scope of the present invention.

[0093] The examples and comparative examples were measured by the following method.

[0094] (1) Analysis of the crystal structure The crystal structure of zirconium oxide nanoparticles was analyzed using an X-ray diffractometer (Rigaku Corporation, RINT-TTRIII). The measurement conditions were as follows: X-ray source: CuKα (0.154nm) X-ray output settings: 50kV, 300mA Sampling width: 0.0200° Scan speed: 10.0000° / min Measurement range: 10~75° Measurement temperature: 25℃

[0095] (2) Determination of the proportion of tetragonal and monoclinic crystals Based on values ​​calculated using an X-ray diffractometer (Rigaku Corporation, RINT-TTRIII), the proportions of tetragonal and monoclinic crystals were quantified using the reference intensity ratio method (RIP method) with calculation software (Rigaku Corporation, PDXL) (peak assignments were also made according to the specifications of the calculation software). Note that in this measurement, it is difficult to distinguish between tetragonal and cubic crystals, and even if cubic crystals are present, their proportion is counted as that of tetragonal crystals.

[0096] (3) Calculation of crystallite size by X-ray diffraction analysis The crystallite size of zirconium oxide nanoparticles was calculated using calculation software (PDXL, Rigaku Corporation) based on the full width at half maximum of the 30° peak, which was analyzed and calculated using an X-ray diffractometer (RINT-TTRIII, Rigaku Corporation).

[0097] (4) Measurement of average primary particle size using an electron microscope The average primary particle diameter of coated zirconium oxide nanoparticles (hereinafter referred to as coated zirconium oxide nanoparticles) was measured by observation using an ultra-high-resolution field emission scanning electron microscope (Hitachi High-Technologies Corporation, S-4800). Coated zirconium oxide particles were observed at a magnification of 150,000x, and the length along the long axis of each particle was measured for any 100 particles. The average value of these measurements was defined as the average primary particle diameter.

[0098] (5) Measurement of organic content Using a TG-DTA (thermogravimetric-indicative thermal analysis) apparatus, coated zirconium oxide nanoparticles were heated from room temperature to 800°C at a rate of 10°C / min under an air atmosphere, and the weight (mass) loss rate of the particles was measured. This weight (mass) loss rate was defined as the organic content of the coated zirconium oxide nanoparticles.

[0099] (6) Viscosity evaluation of monomer dispersion The viscosity of the monomer dispersion of zirconium oxide nanoparticles was measured using a viscometer (TVE-22L viscometer manufactured by Toki Sangyo Co., Ltd.). Set temperature: 20℃ Sample volume: 0.2 mL Preheat time: 1 minute Measurement time: 1 minute Cone rotor: 3° × R9.7

[0100] (7) Measurement of refractive index of monomer dispersion The refractive index of the monomer dispersion of coated zirconium oxide nanoparticles was measured using an ATAGO DR-M4 multi-wavelength Abbe refractometer (measurement temperature 20°C, interference filter wavelength 589(D)nm).

[0101] (8) Measurement of total light transmittance The total light transmittance of the coated zirconium oxide particle monomer dispersion was measured using a turbidimeter (NDH7000, manufactured by Nippon Denshoku Industries Co., Ltd.). For sample preparation, 100 μm thick spacers were placed at both ends of a large microscope slide (manufactured by Matsunami Glass Industry Co., Ltd., part number: S9112), and 0.5 g of the dispersion was weighed into the center. Another large microscope slide was then placed on top, ensuring no air bubbles were introduced, to serve as the sample.

[0102] (9) Measurement of HAZE The haze of the monomer dispersion of coated zirconium oxide nanoparticles was measured using a turbidimeter (NDH7000, Nippon Denshoku Industries Co., Ltd.). For sample preparation, 100 μm thick spacers were placed at both ends of a large microscope slide (Matsunami Glass Industry Co., Ltd., part number: S9112), and 0.5 g of the dispersion was weighed into the center. Another large microscope slide was then placed on top, ensuring no air bubbles were introduced, to create the sample.

[0103] (10) Evaluation of curability A coated zirconium oxide nanoparticle-containing composition was applied onto a large slide glass (manufactured by Matsunami Glass Industry Co., Ltd., product number: S9112) using applicator #01, and the composition was irradiated with 700 mJ / cm 2 of ultraviolet light using a high-pressure mercury lamp. The number of irradiations was increased, and the time point at which fingerprints no longer formed on the coating film was judged as curing, and the number of irradiations required for curing was confirmed.

[0104] (11) Appearance evaluation of cured film A coated zirconium oxide nanoparticle-containing composition was applied onto a large slide glass (manufactured by Matsunami Glass Industry Co., Ltd., product number: S9112) using applicator #01, and 700 mJ / cm 2 of ultraviolet light from a high-pressure mercury lamp was applied multiple times to cure the composition, thereby obtaining a cured film (dry film thickness: 0.1 μm). The appearance (color, cracks) of the cured film was visually checked.

[0105] (12) Heat resistance evaluation of cured product 20 mg of the coated zirconium oxide nanoparticle-containing composition was charged into a deep aluminum pan for thermal analysis, and the composition was irradiated with 15000 mJ / cm 2 of ultraviolet light using a high-pressure mercury lamp to prepare a sample. Using a TG-DTA (thermogravimetry-differential thermal analysis) apparatus, the sample was heated from room temperature to 800°C at a rate of 10°C / min under an air atmosphere, the temperature at which the weight (mass) reduction rate reached 5% was confirmed, and heat resistance was evaluated.

[0106] (13) Film thickness evaluation of cured thin film 0.1 g of the coated zirconium oxide nanoparticle-containing composition was weighed onto an optical glass substrate (5 cm × 5 cm), and applied by a spin coater (3000 rpm, 30 seconds). After drying at 80°C for 1 minute, the composition was irradiated with 2000 mJ / cm 2 of ultraviolet light using a high-pressure mercury lamp to prepare a cured film. The film thickness was measured using a thin film measurement apparatus (manufactured by FILMETRICS).

[0107] (14) Refractive index evaluation of cured thin film A 0.1 g composition containing coated zirconium oxide nanoparticles was weighed onto an optical glass substrate (5 cm x 5 cm) and coated using a spin coater (3000 rpm, 30 seconds). It was dried at 80°C for 1 minute and then heated with a high-pressure mercury lamp at 2000 mJ / cm². 2 A cured film was prepared by irradiating it with ultraviolet light. The refractive index was measured using a thin film measuring device (manufactured by FILMETRICS).

[0108] [Production Example 1: Production of coated zirconium oxide nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid (coated ZrO2 particles 1)] 782 g of zirconium 2-ethylhexanoate mineral spirit solution (44% by mass zirconium 2-ethylhexanoate, manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was mixed with pure water (268 g). The resulting mixture was placed in an autoclave equipped with a stirrer, and the atmosphere inside the autoclave was replaced with nitrogen gas. The mixture was then heated to 180°C and held at this temperature for 16 hours (autoclave pressure of 0.94 MPa) to react and produce zirconium oxide nanoparticles. Subsequently, the mixture was removed after the reaction, the precipitate accumulated at the bottom was filtered off and washed with acetone, and then dried. When the dried precipitate (100 g) was dispersed in toluene (800 mL), a cloudy solution was obtained. Next, as a purification step, the solution was filtered again using quantitative filter paper (Advantec Toyo Co., Ltd., No. 5C) to remove coarse particles from the precipitate. Furthermore, white zirconium oxide nanoparticles (coated ZrO2 particles 1) were recovered by concentrating the filtrate under reduced pressure to remove toluene.

[0109] The crystal structure of the obtained coated ZrO2 particles 1 was confirmed according to the above-described "(1) Analysis of Crystal Structure" and "(2) Determination of the Ratio of Tetragonal and Monoclinic Crystals." Diffraction lines attributed to tetragonal and monoclinic crystals were detected. From the intensity of the diffraction lines, the ratio of tetragonal to monoclinic crystals was determined to be 54 / 46, and the crystallite size calculated by the above-described "(3) Calculation of Crystallite Size by X-ray Diffraction Analysis" was 5 nm. Furthermore, the average particle size (number-mean primary particle size) of the coated ZrO2 particles 1, measured by the above-described "(4) Measurement of Average Primary Particle Size by Electron Microscopy," was 12 nm. In addition, analysis of the obtained coated ZrO2 particles 1 by infrared absorption spectroscopy revealed absorption originating from CH and absorption originating from COOH. These absorptions are thought to be due to 2-ethylhexanoic acid and / or carboxylates derived from 2-ethylhexanoic acid coating the coated zirconium oxide particles.

[0110] The organic content of coated ZrO2 particles 1, measured according to "(5) Measurement of Organic Content" described above, was 12% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating coated ZrO2 particles 1 constituted 12% by mass of the entire coated ZrO2 particles 1.

[0111] [Production Example 2: Production of zirconium oxide nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid and 2-acryloyloxyethyl succinate (coated ZrO2 particles 2)] The coated ZrO2 particles 1 (10 g) obtained in the above Production Example 1 and 2-acryloyloxyethyl succinate (1.5 g) were stirred and mixed in propylene glycol monomethyl ether acetate (12 g, hereinafter referred to as "PGMEA") until uniformly dispersed. Next, n-hexane (36 g) was added to agglomerate the dispersed particles and make the solution cloudy, and the agglomerated particles were separated from the cloudy liquid using filter paper. Subsequently, the separated agglomerated particles were added to n-hexane (36 g), stirred for 10 minutes, and the agglomerated particles were separated using filter paper. The resulting particles were vacuum-dried at room temperature to prepare zirconium oxide nanoparticles (coated ZrO2 particles 2) surface-treated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid and 2-acryloyloxyethyl succinate.

[0112] The obtained coated ZrO2 particles 2 were dispersed in deuterated chloroform to be used as the measurement sample. 1 Analysis was performed using 1H-NMR. The results showed that the molar ratio of carboxylate derived from 2-ethylhexanoic acid and / or 2-ethylhexanoic acid to 2-acryloyloxyethyl succinate was 24:76.

[0113] The organic content of coated ZrO2 particles 2, measured according to "(5) Measurement of Organic Content" above, was 18% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid, and 2-acryloyloxyethyl succinate, which coat the coated zirconium oxide particles, account for 18% by mass of the total coated ZrO2 particles.

[0114] [Manufacturing Example 3: Preparation of Zirconium Oxide Particle Monomer Dispersion] Coated ZrO2 particles 2 (20 g) obtained in Production Example 2 and m-phenoxybenzyl acrylate (hereafter, PBZA) (5.0 g) were blended and uniformly stirred to obtain PBZA dispersion 1 with a coated zirconium oxide nanoparticle content of 80%. The viscosity of PBZA dispersion 1 is 18840 mPa·s at 20°C.

[0115] Example 1 Coated zirconium oxide nanoparticle dispersion 1 (2.0 g) obtained in Production Example 3 was mixed with tripropylene glycol-bis(2-(allyloxymethyl)acrylate) (manufactured by Nippon Shokubai Co., Ltd., hereafter referred to as TPG-AOMA) (0.11 g) represented by the following formula, and uniformly stirred to obtain PBZA and TPG-AOMA dispersions with a coated zirconium oxide nanoparticle content of 76%.

[0116] [ka]

[0117] Comparative Example 1 By mixing the zirconium oxide particle dispersion 1 (2.0 g) obtained in Production Example 3 with light acrylate 4EG-A (manufactured by Kyoei Chemical Co., Ltd.) (0.11 g) and uniformly stirring, a PBZA and light acrylate 4EG-A dispersion with a coated zirconium oxide nanoparticle content of 76% was obtained.

[0118] Table 1 shows the results of (6) viscosity evaluation of the monomer dispersion and (7) refractive index measurement of the monomer dispersion for the zirconium oxide particle monomer dispersion obtained in Example 1 and Comparative Example 1.

[0119] [Table 1]

[0120] The viscosity of the dispersion is affected by the molecular weight of the monomers contained in the dispersion; therefore, in Comparative Example 1, a monomer with a molecular weight equivalent to that of AOMA-TPG was used. In addition, the composition of the dispersion was adjusted in Example 1 and Comparative Example 1 so that the refractive index was equivalent. As shown in Table 1, when the refractive index of the dispersion was made the same, the viscosity was reduced when using the crosslinkable compound of the present invention compared to other monomers with equivalent molecular weight, demonstrating a useful effect as a reactive diluent.

[0121] The viscosity of AOMA-TPG used in Example 1 at 20°C was 19.8 mPa·s, and the viscosity of light acrylate 4EG-A used in Comparative Example 1 at 20°C was 11.0 mPa·s. Thus, AOMA-TPG has a higher viscosity when used alone. However, as can be seen from Table 1 above, the dispersion in Example 1, which uses the higher viscosity AOMA-TPG, has a lower viscosity, demonstrating the unique effect of the present invention.

[0122] Example 2 By combining the coated ZrO2 particles (3.0 g) and TPG-AOMA (2.0 g) obtained in Production Example 2 and uniformly stirring, a TPG-AOMA dispersion with a coated zirconium oxide nanoparticle content of 60% was obtained.

[0123] Comparative Example 2 By mixing 2 (3.0 g) of coated ZrO2 particles obtained in Production Example 2 with 2 (2.0 g) of tripropylene glycol diacrylate (hereinafter referred to as TPGDA) and stirring uniformly, a TPGDA dispersion with a coated zirconium oxide nanoparticle content of 60% was obtained.

[0124] Table 2 shows the results of the following measurements of the zirconium oxide particle monomer dispersions obtained in Example 2 and Comparative Example 2: (6) viscosity evaluation of the monomer dispersion, (7) refractive index measurement of the monomer dispersion, (8) total light transmittance measurement, and (9) HAZE measurement.

[0125] [Table 2]

[0126] In Example 2 and Comparative Example 2, where the skeletons of the dispersion medium (monomers) contained in the dispersion are similar, a comparison of the refractive indices of the dispersions shows that Example 2 exhibits a higher refractive index.

[0127] Example 3 In Example 2, 3.0 g of the dispersion was placed in a brownish glass bottle with 0.036 g of Irgacure 184 (a photoradical polymerization initiator, manufactured by BASF), and the mixture was stirred until homogeneous to obtain a zirconium oxide particle-containing composition.

[0128] Comparative Example 3 In Comparative Example 2, 3.0 g of the dispersion was placed in a brownish glass bottle with 0.036 g of Irgacure 184 (a photoradical polymerization initiator, manufactured by BASF), and the mixture was stirred until homogeneous to obtain a zirconium oxide particle-containing composition.

[0129] The zirconium oxide particle-containing compositions obtained in Example 3 and Comparative Example 3 were evaluated according to (10) curability evaluation, (11) appearance evaluation of the cured film, and (12) heat resistance evaluation of the cured product. The results are shown in Table 3.

[0130] [Table 3]

[0131] Table 3 shows that Example 3 exhibits superior thermal stability of the cured product compared to Comparative Example 3, and can be cured with less energy (fewer UV irradiations).

[0132] Example 4 In Example 2, 1.0 g of the dispersion was placed in a brownish glass bottle along with 0.040 g of Irgacure 184 (a photoradical polymerization initiator, manufactured by BASF) and 5.89 g of propylene glycol monomethyl ether (hereinafter referred to as PGM) as a dispersion medium. The mixture was then uniformly stirred to obtain a zirconium oxide particle-containing composition.

[0133] Comparative Example 4 In Comparative Example 2, 1.0 g of the dispersion, 0.040 g of Irgacure 184 (a photoradical polymerization initiator, manufactured by BASF), and 5.78 g of PGM as a dispersion medium were placed in a brownish glass bottle and uniformly stirred to obtain a zirconium oxide particle-containing composition.

[0134] Table 4 shows the results of evaluating the zirconium oxide particle-containing compositions obtained in Example 4 and Comparative Example 4 according to (13) evaluation of the thickness of the cured film and (14) evaluation of the refractive index of the cured film.

[0135] [Table 4]

[0136] Table 4 shows that Example 4 exhibits a higher refractive index compared to Comparative Example 4.

Claims

1. The material contains zirconium oxide nanoparticles and a crosslinkable compound represented by the following formula (1): Does not contain other polymerizable monomers, or comprising other polymerizable monomers, wherein the other polymerizable monomer is one or more selected from crosslinkable (meth)acrylic acid esters, polyfunctional styrene monomers, polyfunctional allyl ester monomers, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, or urethane acrylate oligomers, and monofunctional monomers. The composition is characterized in that the zirconium oxide nanoparticles are coated with a coating agent containing a secondary carboxylic acid. 【Chemistry 1】 In formula (1), Z represents an n-valent linking group composed of n1 linearly linked Qs, two Xs that bond the Qs at both ends to the α-allyloxymethylacryloyl group in formula (1), and (n1-1) Ys that bond adjacent Qs. Q is a saturated hydrocarbon having 2 to 6 carbon atoms, and X and Y are linked by ether bonds. n1 is between 2 and 10, and n represents 2.

2. The composition according to claim 1, wherein the monofunctional monomer is a compound that contains two or more aromatic rings and has one polymerizable double bond in one molecule.

3. A cured product of the composition according to claim 1 or 2.

Images