Active energy ray-curable composition, and cured product thereof

Abstract

The present invention makes it possible to provide: an active energy ray-curable composition which has favorable self-curing properties, a high refractive index and a low viscosity; and a cured product thereof. This active energy ray-curable composition contains inorganic particles (A), a (meth) acrylate compound (B), and a photopolymerization initiator (C). The content of the inorganic particles (A) in the active energy ray-curable composition is 30-60 mass%, inclusive. The value of a parameter NdCH2 (number of unsaturated double bonds) generated from the composition of the active energy ray-curable composition is 1.0-4.0, the value of a parameter RotRatio (rotatable bond ratio) is 0.2-0.85, and the value of a parameter ARR (rotatable bond ratio) is 0.5-1.3.

Description

Active energy ray curable composition and cured product thereof

[0001] The present invention relates to an active energy ray-curable composition and a cured product thereof. This application claims priority to Japanese Patent Application No. 2023-111971, filed on July 7, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, optical sheets have been used in displays such as liquid crystal display devices, providing functions such as improved brightness and a wider viewing angle. Such optical sheets typically comprise a substrate and an optical functional layer on the substrate, which has a finely textured structure. The textured structure modulates light through geometric optical effects such as refraction, thereby achieving the desired function. Because such textured structures are typically produced by shaping a resin material using a metal mold, the material used for the optical functional layer must be solvent-free and low-viscosity. Furthermore, among the optical sheets, prism sheets, for example, have sharp convex shapes that make them prone to chipping due to contact with adjacent components. Flexibility and self-healing properties are particularly important for such optical sheets. Meanwhile, with the trend toward thinner displays and reduced power consumption, materials used for the optical functional layer must have a high refractive index. To address this demand, methods have been proposed, such as using monofunctional (meth)acrylates with high refractive index and low viscosity, or adding organic or inorganic high-refractive-index fine particles (e.g., Patent Documents 1 to 3).

[0003] International Publication No. 2020 / 250721 Japanese Patent Application Laid-Open No. 2013-249439 Japanese Patent Application Laid-Open No. 2010-85539

[0004] However, materials with high refractive indexes generally reduce the flexibility of the cured resin, making the uneven surface prone to chipping. Therefore, there has been a demand for materials with good self-healing properties, a high refractive index, and low viscosity.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an active energy ray-curable composition having good self-healing properties, a high refractive index, and a low viscosity, and a cured product thereof.

[0006] The present disclosure includes the following embodiments. [1] An active energy ray-curable composition containing inorganic particles (A), a (meth)acrylate compound (B), and a photopolymerization initiator (C), wherein the content of the inorganic particles (A) in the active energy ray-curable composition is 30% by mass or more and 60% by mass or less, the value of a parameter NdCH2 generated from the composition of the active energy ray-curable composition is 1.0 to 4.0, the value of a parameter RotRatio generated from the composition of the active energy ray-curable composition is 0.2 to 0.85, and the value of a parameter ARR generated from the composition of the active energy ray-curable composition is 0.5 to 1.3. The parameter NdCH2 is a value calculated using the NdCH2 (compound) of each component contained in the active energy ray-curable composition, and the NdCH2 (compound) is a parameter calculated by the following formula (1): NdCH2 (compound) = number of unsaturated double bonds / 1 molecule (1) The parameter RotRatio is a value calculated using the RotRatio (compound) of each component contained in the active energy ray-curable composition, and the RotRatio (compound) is a parameter calculated by the following formula (2): RotRatio = number of rotatable bonds / total number of bonds (2) The parameter ARR is a value calculated using the ARR (compound) of each component contained in the active energy ray-curable composition, and the ARR (compound) is a parameter calculated by the following formula (3): ARR = number of aromatic bonds / total number of bonds (3) [2] The active energy ray-curable composition according to [1], wherein the inorganic particles (A) are zirconia. [3] The active energy ray-curable composition according to [1] or [2], wherein the particle diameter of the inorganic particles (A) measured by dynamic light scattering is 1 to 100 nm. [4] The active energy ray-curable composition according to any one of [1] to [3], wherein the (meth)acrylate compound (B) contains a biphenyl structure. [5] The active energy ray-curable composition according to any one of [1] to [4], wherein the (meth)acrylate compound (B) contains biphenylmethyl (meth)acrylate.[6] The active energy ray-curable composition according to any one of [1] to [5], wherein the active energy ray-curable composition is used for a shaped optical film. [7] A cured product of the active energy ray-curable composition according to any one of [1] to [6]. [8] A shaped optical film comprising the cured product according to [7]. [9] An optical sheet comprising the cured product according to [7].

[0007] According to the present invention, it is possible to provide an active energy ray-curable composition having good self-healing properties, a high refractive index and a low viscosity, and a cured product thereof.

[0008] FIG. 1 is a diagram illustrating a method for measuring the elastic deformation power (nIT).

[0009] The present invention will be described in further detail below, but the present invention is not limited to the following embodiments.

[0010] The symbol "to" means greater than or equal to the value before "to" and less than or equal to the value after "to". "(Meth)acrylic" is a general term for acrylic and methacrylic, and "(meth)acrylate compound (B)" is a general term for acrylate compounds and methacrylate compounds.

[0011] (Active energy ray-curable composition) The active energy ray-curable composition according to this embodiment contains inorganic particles (A), a (meth)acrylate compound (B), and a photopolymerization initiator (C). The content of the inorganic particles (A) in the active energy ray-curable composition is 30% by mass or more and 60% by mass or less. The value of the parameter NdCH2 generated from the composition of the active energy ray-curable composition is 1.0 to 4.0. The value of the parameter RotRatio generated from the composition of the active energy ray-curable composition is 0.2 to 0.85. The value of the parameter ARR generated from the composition of the active energy ray-curable composition is 0.5 to 1.3.

[0012] The parameter NdCH2 is a value calculated using the NdCH2 of each compound in the composition (hereinafter referred to as "NdCH2 (compound)"). "NdCH2 (compound)" is the number of unsaturated double bonds in one molecule and is expressed by the following formula (1). The method for calculating the parameter NdCH2 will be explained in detail later.

[0013] NdCH2 (compound) = number of unsaturated double bonds / 1 molecule (1)

[0014] The parameter RotRatio is a value calculated using the RotRatio of each compound in the composition (hereinafter referred to as "RotRatio (compound)"). "RotRatio (compound)" is the ratio of rotatable bonds and is expressed by the following formula (2). The method for calculating the parameter RotRatio will be explained in detail later.

[0015] RotRatio (compound) = number of rotatable bonds / total number of bonds (2)

[0016] The parameter ARR is a value calculated using the ARR of each compound in the composition (hereinafter referred to as "ARR (compound)"). "ARR (compound)" is the aromatic bond ratio, and is a parameter calculated by the following formula (3). The method for calculating the parameter ARR will be described in detail later.

[0017] ARR (compound) = number of aromatic bonds / total number of bonds (3)

[0018] The "parameter generated from the composition of the active energy ray-curable composition" is the weighted sum of the molar mass concentrations of the compounds constituting the composition multiplied by 1000. Note that the weighted sum does not include the inorganic particles (A), but does include other organic components (including the (meth)acrylate compound (B), the photopolymerization initiator (C), other dispersants, additives, initiators, solvents, etc.).

[0019] [Parameter NdCH2, unit: mmol / g] The parameter NdCH2 that defines the active energy ray-curable composition of the present embodiment is obtained from the NdCH2 (compound) of each compound constituting the active energy ray-curable composition of the present embodiment and the composition ratio of each compound. For example, when the active energy ray-curable composition contains each compound component a１ ~a ｎ Each component a １ ~a ｎ The molar amount (weight ratio divided by molecular weight) of the compound of p １ ~p ｎ Each component a １ ~a ｎ From the compound structure, each NdCH2 (compound) can be calculated (b １ ~b ｎ The parameter NdCH2 of the active energy ray-curable composition is calculated by multiplying the content p of each component by the calculated NdCH2 (compound) of each component, as shown in the following formula (4). １ ~p ｎ The weighted sum is multiplied by 1000.

[0020] NdCH2 = (Σb ｎ ×p ｎ ) x 1000 (4)

[0021] The term "unsaturated double bond" refers to a bond having a double bond between carbon atoms, and indicates a bond consisting of one σ bond and one π bond. Resins having unsaturated double bonds are cured by a polymerization reaction using radicals or cations generated by irradiation with ultraviolet light as initiator species. Examples of compounds having unsaturated double bonds include ethylene, acetylene, styrene, allyl compounds, and methyl (meth)acrylate.

[0022] For example, in Example 1 described later, the parameter NdCH2 was 2.0, which was calculated from the composition shown in Table 1 according to formula (4) as follows:

[0023] Parameter NdCH2 (Example 1) = {(UEP-100: No addition) + (Dispersant (1): 0.95 × 3.2 ÷ 100 ÷ 438) + (KBM-503: 1 × 9.5 ÷ 100 ÷ 248) + (KOMERATE A011: 1 × 2.3 ÷ 100 ÷ 268) + (Photomer 4035: 1 × 18.3 ÷ 100 ÷ 192) + (MIRAMER M1192: 1 × 3.8 ÷ 100 ÷ 238) + (ACMO: 1 × 4.4 ÷ 100 ÷ 141) + (MIRAMER M2100: 2 × 1.49 ÷ 100 ÷ 777) + (Runtecure 1104: 0 x 1 ÷ 100 ÷ 204) + (Runtecure 1108: 0 x 1 ÷ 100 ÷ 348)} x 1000 = 2.0

[0024] The NdCH (compound) of each component compound contained in the active energy ray-curable composition of this embodiment may be calculated from the molecular structure of each compound using, for example, software for calculating molecular descriptors. Examples of such software include Dragon (version 7.0) and alvaDesc.

[0025] The parameter NdCH2 of the active energy ray-curable composition of this embodiment is 1.0 or more, preferably 1.2 or more, and more preferably 1.5 or more. It may be 1.95 or more, or 2.0 or more. It is also 4.0 or less, preferably 3.0 or less, and more preferably 2.5 or less. By setting it within these ranges, it is possible to achieve good self-healing properties, low viscosity, and a high refractive index all at once.

[0026] [Parameter RotRatio, Unit: mmol / g] The parameter RotRatio, which defines the active energy ray-curable composition of this embodiment, is obtained from the RotRatio (compound) of each compound constituting the active energy ray-curable composition of this embodiment and the compositional ratio of each compound, using a method similar to that for the parameter NdCH2 described above. That is, the RotRatio (compound) of each compound is weighted according to the content of each component to calculate a weighted sum, and this weighted sum is multiplied by 1000. Note that the term "rotatable bond" refers to single bonds connecting heavy atoms, excluding single bonds contained in ring structures and single bonds connecting terminal heavy atoms to other heavy atoms. Heavy atoms refer to atoms other than hydrogen atoms and helium atoms, and specific examples include heteroatoms such as nitrogen atoms and oxygen atoms, and carbon atoms. Specific examples of single bonds connecting heavy atoms are carbon-carbon bonds and carbon-heteroatom bonds.

[0027] The RotRatio (compound) of each component compound contained in the active energy ray-curable composition of the present embodiment may be calculated from the molecular structure of each compound using, for example, software for calculating molecular descriptors. Examples of such software include Dragon (version 7.0) and alvaDesc.

[0028] The parameter RotRatio of the active energy ray-curable composition of this embodiment is 0.1 or more, preferably 0.3 or more, and more preferably 0.5 or more. It may be 0.65 or more, or 0.70 or more. It is also 0.85 or less, preferably 0.8 or less, and more preferably 0.75 or less. By setting the parameter RotRatio within these ranges, it is possible to achieve both good self-healing properties, low viscosity, and a high refractive index.

[0029] [Parameter ARR, unit: mmol / g] The parameter ARR that defines the active energy ray-curable composition of this embodiment is obtained from the ARR (compound) of each compound constituting the active energy ray-curable composition of this embodiment and the composition ratio of each compound, using a method similar to that for the parameter NdCH2 described above. That is, the ARR (compound) of each compound is weighted according to the content of each component to calculate a weighted sum, and this weighted sum is multiplied by 1000. Note that the term "aromatic bond" refers to a covalent bond formed when carbon atoms in an aromatic ring share a shared electron pair. Examples of compounds having an aromatic bond include benzene, phenol, and styrene.

[0030] The ARR (compound) of each component compound contained in the active energy ray-curable composition of the present embodiment may be calculated from the molecular structure of each compound using, for example, software for calculating molecular descriptors. Examples of such software include Dragon (version 7.0) and alvaDesc.

[0031] The parameter ARR of the active energy ray-curable composition of this embodiment is 0.5 or more, preferably 0.55 or more, and more preferably 0.6 or more. Also, it is 1.3 or less, preferably 1.2 or less, and more preferably 1.1 or less. By setting it within these ranges, it is possible to achieve good self-healing properties, low viscosity, and a high refractive index all at once.

[0032] [Inorganic particles (A)] The inorganic particles (A) according to this embodiment are preferably one or more selected from the group consisting of zirconia, silica, barium sulfate, zinc oxide, barium titanate, cerium oxide, alumina, and titanium oxide. The inorganic particles (A) according to this embodiment are more preferably zirconia. The crystalline structure of the inorganic particles (A) according to this embodiment is not particularly limited, but for example, when the inorganic particles (A) are zirconia, a monoclinic system is preferred because it provides excellent dispersion stability and a cured product with high light transmittance and refractive index.

[0033] The inorganic particles (A) according to the present embodiment may be any known particles, and the particle shape is not particularly limited, but may be, for example, spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous. Among these, spherical particles are preferred because they provide excellent dispersion stability and a cured product with high light transmittance and refractive index.

[0034] The average particle size of the inorganic particles (A) according to this embodiment is preferably 100 nm or less, more preferably in the range of 1 to 100 nm, and even more preferably in the range of 20 to 100 nm, since this results in a cured product with a high refractive index and excellent light transmittance. The particle size is measured by dynamic light scattering.

[0035] The content of the inorganic particles (A) in the active energy ray-curable composition is 30% by mass or more and 60% by mass or less. The content of the inorganic particles (A) in the active energy ray-curable composition is 30% by mass or more, preferably 35% by mass or more, and more preferably 40% by mass or more. The content is 60% by mass or less, preferably 55% by mass or less, and more preferably 50% by mass or less. By setting the content within these ranges, good self-healing properties and low viscosity can be achieved at the same time.

[0036] <Zirconia Nanoparticles> The inorganic particles (A) according to this embodiment are preferably zirconia nanoparticles. Conventional zirconia nanoparticles can be used. The particle shape is not particularly limited, but examples include spherical, hollow, porous, rod-like, and fibrous shapes. Of these, spherical shapes are preferred. The average primary particle diameter of the zirconia nanoparticles according to this embodiment is preferably 1 to 50 nm, more preferably 1 to 30 nm. Furthermore, the crystal structure is not particularly limited, but a monoclinic system is preferred. The average primary particle diameter in this embodiment can be measured by directly measuring the size of primary particles from electron micrographs using a transmission electron microscope (TEM). For example, the measurement method involves measuring the minor axis diameter and major axis diameter of each inorganic particle and averaging the measured values ​​to determine the average primary particle diameter of the primary particles. Specific examples of zirconia nanoparticles according to this embodiment include UEP-100 (average primary particle diameter: 11 nm) manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd. and PCS (average primary particle diameter: 20 nm) manufactured by Nippon Denko Corporation.

[0037] [(Meth)acrylate Compound (B)] Examples of the (meth)acrylate compound (B) according to this embodiment include conventionally known monofunctional (meth)acrylates or polyfunctional (meth)acrylates having a (meth)acryloyl group or a (meth)acryloyloxy group for forming optical sheets. Oligomers, prepolymers, or the like can be used as needed. The (meth)acrylate compound (B) according to this embodiment preferably contains a monofunctional (meth)acrylate having one active energy ray-curable group and a polyfunctional (meth)acrylate having two or more active energy ray-curable groups. The active energy ray-curable group is preferably a (meth)acryloyl group. The (meth)acrylate compound (B) according to this embodiment preferably contains a biphenyl structure, and more preferably contains biphenylmethyl (meth)acrylate. The (meth)acrylate compound (B) according to this embodiment does not include a dispersant (D) having a (meth)acryloyl group, or a silane coupling agent (E) having a (meth)acryloyl group or a (meth)acryloyloxy group.

[0038] <Monofunctional (meth)acrylate> The monofunctional (meth)acrylate is a monofunctional (meth)acrylate having one active energy ray-curable group. The monofunctional (meth)acrylate may be a chain aliphatic, cyclic alicyclic, or aromatic (meth)acrylate containing a heteroatom such as a halogen atom, a sulfur atom, an oxygen atom, or a nitrogen atom. The monofunctional (meth)acrylate may be, for example, the monofunctional (meth)acrylate described in Patent Document 1.

[0039] Examples of the monofunctional (meth)acrylate include aromatic mono(meth)acrylate compounds, aliphatic mono(meth)acrylate compounds, alicyclic mono(meth)acrylate compounds, heterocyclic mono(meth)acrylate compounds, and hydroxyl group-containing mono(meth)acrylate compounds. Examples of the monofunctional (meth)acrylate include polyoxyalkylene-modified mono(meth)acrylate compounds in which a polyoxyalkylene chain such as a polyoxyethylene chain, a polyoxypropylene chain, or a polyoxytetramethylene chain is introduced into the molecular structure of the various mono(meth)acrylate compounds; and lactone-modified mono(meth)acrylate compounds in which a (poly)lactone-derived structure is introduced into the molecular structure of the various mono(meth)acrylate compounds.

[0040] Examples of the aromatic mono(meth)acrylate compound include benzyl(meth)acrylate, phenyl(meth)acrylate, phenoxy(meth)acrylate, phenoxyethyl(meth)acrylate, phenoxyethoxyethyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, phenoxybenzyl(meth)acrylate, biphenylmethyl(meth)acrylate, benzylbenzyl(meth)acrylate, phenylphenoxyethyl(meth)acrylate, phenylphenol(EO)n(meth)acrylate, and phenol(EO)n(meth)acrylate.

[0041] Examples of the aliphatic mono(meth)acrylate compound include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, n-pentyl(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Examples of the alicyclic mono(meth)acrylate compounds include cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, adamantyl mono(meth)acrylate, cyclohexylmethyl(meth)acrylate, cyclohexylethyl(meth)acrylate, dicyclopentanyl(meth)acrylate, dicyclopentanyloxyethyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate, etc. Examples of the heterocyclic mono(meth)acrylate compounds include glycidyl(meth)acrylate, tetrahydrofurfuryl acrylate, etc. Examples of the hydroxyl group-containing mono(meth)acrylate compounds include hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, etc. Examples of the lactone-modified mono(meth)acrylate compound include caprolactone-modified tetrahydrofurfuryl(meth)acrylate.

[0042] The monofunctional (meth)acrylate preferably contains an aromatic mono(meth)acrylate compound, and more preferably contains a compound containing two aromatic rings in one molecule. It is particularly preferred that the compound containing two aromatic rings in one molecule is biphenylmethyl(meth)acrylate. Examples of the compound containing two aromatic rings in one molecule (aromatic mono(meth)acrylate compound) include phenoxybenzyl(meth)acrylate, biphenylmethyl(meth)acrylate, benzylbenzyl(meth)acrylate, phenylphenoxyethyl(meth)acrylate, phenylphenol(EO)n(meth)acrylate, and (1-naphthyl)methyl acrylate.

[0043] Specific examples of the monofunctional (meth)acrylate include the following monofunctional (meth)acrylates used in the examples: Compound (B1-1): orthophenylphenol (EO) acrylate, trade name: KOMERATE A011 (manufactured by Green Chemical Co., Ltd.) Compound (B1-2): biphenyl methyl acrylate, trade name: MIRAMER M1192 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Compound (B1-3): 3-phenoxybenzyl acrylate, trade name: KOMERATE A008 (manufactured by Green Chemical Co., Ltd.) Compound (B1-4): (1-naphthyl)methyl acrylate, trade name: Light Acrylate NMT-A (manufactured by Kyoei Chemical Co., Ltd.) Compound (B1-5): phenoxyethyl acrylate, trade name: Photomer 4035 (manufactured by IGM Resins Inc.) Compound (B1-6): benzyl acrylate, trade name: MIRAMER M1182 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.)

[0044] The monofunctional (meth)acrylate may be used alone or in combination of two or more. The content of the monofunctional (meth)acrylate in the (meth)acrylate compound (B) may be 70% by mass, 75% by mass or more, 80% by mass or more, or 85% by mass or more. It may also be 95% by mass or less, or 90% by mass or less. When the content of the monofunctional (meth)acrylate is within the above range, the self-healing property is good, and the refractive index and viscosity are high.

[0045] When the monofunctional (meth)acrylate contains a compound containing two aromatic rings in one molecule (aromatic mono(meth)acrylate compound), such as biphenylmethyl(meth)acrylate, the content of the compound containing two aromatic rings in one molecule, such as biphenylmethyl(meth)acrylate, in the monofunctional (meth)acrylate is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The content of the compound is not particularly limited, and a higher value is preferable. From the viewpoint of self-healing property, it is preferably 95% by mass or less, more preferably 90% by mass or less. When the compound containing two aromatic rings in one molecule in the monofunctional (meth)acrylate is biphenylmethyl(meth)acrylate, the composition exhibits excellent substrate adhesion, in addition to refractive index, viscosity, and self-healing property.

[0046] [Polyfunctional (meth)acrylate] The (meth)acrylate compound (B) according to this embodiment may contain a polyfunctional (meth)acrylate in addition to the monofunctional (meth)acrylate according to this embodiment.

[0047] The polyfunctional (meth)acrylate is preferably a polyfunctional (meth)acrylate having three or more active energy ray-curable groups, and may be a chain aliphatic, cyclic alicyclic, or aromatic (meth)acrylate containing a heteroatom such as a halogen atom, a sulfur atom, an oxygen atom, or a nitrogen atom, and for example, the polyfunctional (meth)acrylate described in Patent Document 1 can be used.

[0048] Examples of the polyfunctional (meth)acrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, tetrabutylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, glycerol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, caprolactone-modified neopentyl glycol hydroxypivalate di(meth)acrylate, tetrabromobisphenol A di(meth)acrylate, hydropivalaldehyde-modified trimethylolpropane di(meth)acrylate, bisphenol fluorene di(meth)acrylate, bisphenol fluorene (EO) ｎ Di(meth)acrylate, bisphenol A (EO) ｎ Di(meth)acrylate, trimethylolpropane (EO) ｎ tri(meth)acrylate, 1,4-cyclohexanedimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerol tri(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetra(meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

[0049] These polyfunctional (meth)acrylates can be used alone or in combination of two or more. Among these, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, a reaction product of pentaerythritol and acrylic acid, a reaction product of dipentaerythritol and acrylic acid, and the like are preferred, since they can give (meth)acrylic resins excellent in drying properties, ink fluidity, and suitability for high-speed printing.

[0050] An example of the polyfunctional (meth)acrylate according to this embodiment is a mixture of a polyfunctional (meth)acrylate having three active energy ray-curable groups and a polyfunctional (meth)acrylate having four active energy ray-curable groups. Specific examples thereof include a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (containing about 30 to 70% by mass of the triacrylate and about 70 to 30% by mass of the tetraacrylate). An example of such a mixture is "Aronix M-305" (manufactured by Toagosei Co., Ltd., a reaction product of pentaerythritol and acrylic acid, containing about 60% of the triacrylate, with a hydroxyl value of 116 mgKOH / g) used in the examples.

[0051] [Photopolymerization initiator (C)] The photopolymerization initiator (C) according to the present embodiment is not particularly limited as long as it has the function of initiating polymerization of the (meth)acryloyl group of the (meth)acrylate compound (B) according to the present embodiment or the like upon photoexcitation, and examples thereof include an intramolecular bond cleavage type photopolymerization initiator (C) and an intramolecular hydrogen abstraction type photopolymerization initiator (C). For example, a monocarbonyl compound, a dicarbonyl compound, an acetophenone compound, a benzoin ether compound, an acylphosphine oxide compound, an aminocarbonyl compound, etc. can be used.

[0052] Examples of the intramolecular bond cleavage type photopolymerization initiator (C) include acetophenone-based initiators such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoins such as benzoin methyl ether and benzoin isopropyl ether; acylphosphine oxide-based initiators such as 2,4,6-trimethylbenzoin diphenylphosphine oxide; and benzyl and methylphenyl glyoxyesters.

[0053] Examples of the intramolecular hydrogen abstraction type photopolymerization initiator (C) include benzophenones such as benzophenone, o-benzoylmethylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthones such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenones such as Michler's ketone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone. The photopolymerization initiator (C) is preferably 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0054] Commercially available products of the photopolymerization initiator (C) include Omnirad-184, 651, 500, 907, 127, 369, 784, 2959, and TPO-H manufactured by IGM-Resins; and Esacure ONE manufactured by DKSH Japan Co., Ltd. Omnirad-907 and Omnirad-TPO-H are preferred from the viewpoint of obtaining a cured coating film with excellent curability even when added in small amounts. Omnirad-184 is particularly preferred from the viewpoint of low coloration.

[0055] The photopolymerization initiator (C) is not limited to the above compounds and may be any compound capable of initiating polymerization by ultraviolet light. These photopolymerization initiators (C) may be used singly or in combination of two or more. The amount of the photopolymerization initiator (C) used is not particularly limited, but is preferably used in the range of 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the total nonvolatile content of the active energy ray-curable composition of this embodiment. A known organic amine or the like may also be added as a sensitizer. Furthermore, in addition to the above radical polymerization initiator, a cationic polymerization initiator may also be used in combination.

[0056] Specific examples of the photopolymerization initiator (C) according to this embodiment include Runtecure 1108 (manufactured by Runtec Chemical Co., Ltd., structural formula or compound name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide).

[0057] The content of the photopolymerization initiator (C) is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on the nonvolatile mass of the composition, which is the total mass of all the components of the composition excluding the solvent contained in the composition.

[0058] [Dispersant (D)] The active energy ray-curable composition of the present embodiment preferably further contains a dispersant (D) (sometimes referred to as “component (D)”), and it is more preferable that the dispersant (D) contains a phosphate ester.

[0059] <Phosphate Ester> The phosphate ester according to the present embodiment is not particularly limited, and examples thereof include those having a polyester chain, those having a (meth)acryloyl group, etc. Examples of those having a polyester chain include DISPERBYK-110 and DISPERBYK-111 (manufactured by BYK Japan KK).

[0060] Examples of compounds having a (meth)acryloyl group include those represented by the following structural formula (1): The reason for this is that the resulting inorganic particle dispersion has excellent dispersion stability, and the curable composition containing it has low viscosity and can form a cured coating film having high refractive index performance and excellent bleed-out resistance.

[0061] (In the formula R １ is a hydrogen atom or a methyl group, and R ２ is an alkylene chain having 2 to 4 carbon atoms, x is an integer of 4 to 10, y is an integer of 1 or more, and n is an integer of 1 to 3.

[0062] In the phosphate ester compound represented by the structural formula (1), x is preferably 4 or 5, and y is preferably an integer from 2 to 7. This is because the resulting active energy ray-curable composition has low viscosity and can form a cured coating film having high refractive index performance and excellent bleed-out resistance. Furthermore, the dispersant (D) represented by the structural formula (1) (hereinafter sometimes simply referred to as dispersant (1)) may be a mixture in which n in the formula is 1, 2, and / or 3.

[0063] The content of the phosphate ester compound in the active energy ray-curable composition is more preferably in the range of 5 to 40 parts by mass, and even more preferably in the range of 10 to 25 parts by mass, per 100 parts by mass of zirconia, because this allows the formation of a cured coating film having high refractive index performance and excellent bleed-out resistance.

[0064] [Silane Coupling Agent (E)] The active energy ray-curable composition of the present embodiment may further contain a silane coupling agent (E) (sometimes referred to as "component (E)"). Examples of the silane coupling agent (E) according to the present embodiment include (meth)acryloyloxy-based silane coupling agents such as 3-(meth)acryloyloxypropyltrimethylsilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, and 3-(meth)acryloyloxypropyltriethoxysilane; vinyl-based silane coupling agents such as allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane; Epoxy-based silane coupling agents such as diethoxy(glycidyloxypropyl)methylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; styrene-based silane coupling agents such as p-styryltrimethoxysilane; amino-based silane coupling agents such as N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; ureido-based silane coupling agents such as 3-ureidopropyltriethoxysilane; Chloropropyl-based silane coupling agents such as 3-chloropropyltrimethoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane;Examples of suitable silane coupling agents include sulfide-based silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane; and aluminum-based silane coupling agents such as acetoalkoxyaluminum diisopropylate. These silane coupling agents (E) can be used alone or in combination of two or more. Among these, 3-(meth)acryloyloxypropyltrimethoxysilane is preferred due to its good compatibility with the acrylate compound (B). The amount of silane coupling agent (E) used in this embodiment is preferably in the range of 10 to 30 parts by mass per 100 parts by mass of zirconia. This is because the resulting active energy ray-curable composition has excellent dispersion stability, is low in viscosity, and can form a cured coating film with high refractive index performance and excellent bleed-out resistance.

[0065] [Solvent] The active energy ray-curable composition of this embodiment may contain a solvent. The solvent is not particularly limited, and various known organic solvents can be used. Specific examples include cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, acetone, acetylacetone, toluene, xylene, n-butanol, isobutanol, tert-butanol, n-propanol, isopropanol, ethanol, methanol, 3-methoxy-1-butanol, 3-methoxy-2-butanol, ethylene glycol monomethyl ether, ethylene glycol mono-n-butyl ether, 2-ethoxyethanol, 1-methoxy-2-propanol, diacetone alcohol, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 2-ethoxyethyl acetate, butyl acetate, isoamyl acetate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, tetrahydrofuran, and methylpyrrolidone. Among these, methyl ethyl ketone is preferred. Two or more of these organic solvents may be used in combination. The active energy ray-curable composition of this embodiment may contain, for example, the solvent used in synthesizing each resin. Alternatively, the active energy ray-curable composition of this embodiment may be prepared by mixing inorganic particles (A), a solvent, and optional components to prepare an inorganic particle (A) dispersion, and then mixing the dispersion with the (meth)acrylate compound (B) and the photopolymerization initiator (C). The above-mentioned example of containing a solvent is merely an example. Even if a solvent is contained during the preparation of the active energy ray-curable composition of this embodiment, it is preferable that the solvent is ultimately volatilized and the solvent content is kept as low as possible. Therefore, when the active energy ray-curable composition of this embodiment contains a solvent, the content of the solvent in the active energy ray-curable composition is preferably 0 to 5% by mass, and more preferably 0 to 0.1% by mass.

[0066] [Viscosity of active energy ray-curable composition] The viscosity of the active energy ray-curable composition of this embodiment at 25°C is preferably 6500 mPa·s or less, more preferably 3500 mPa·s or less, and even more preferably 1500 mPa·s or less at 25°C. Also, it is preferably 100 mPa·s or more. If it is in this range, the composition is suitable for coating.

[0067] [Method for Preparing Active Energy Ray-Curable Composition] The method for preparing the active energy ray-curable composition of this embodiment is not particularly limited. For example, a method can be mentioned in which a dispersion of inorganic particles (A) is obtained, and then the dispersion of inorganic particles (A) is mixed with the monofunctional (meth)acrylate, the photoinitiator, and, if necessary, the polyfunctional (meth)acrylate and various other additives. The method for producing the active energy ray-curable composition of this embodiment preferably includes the steps of: preparing a dispersion of inorganic particles (A); and mixing the dispersion of inorganic particles (A) with the monofunctional (meth)acrylate, the photoinitiator, and, if necessary, the polyfunctional (meth)acrylate and various other additives. The mixing method is not particularly limited, and can be, for example, a method using a media-type wet disperser.

[0068] In the step of preparing the inorganic particle (A) dispersion, at least a portion of the monofunctional (meth)acrylate, or, if necessary, at least a portion of the polyfunctional (meth)acrylate may be added.

[0069] <Inorganic Particle (A) Dispersion> The inorganic particle (A) dispersion according to this embodiment preferably contains, for example, the inorganic particles (A), the solvent, and the dispersant (D) as the additive. The inorganic particle (A) dispersion according to this embodiment may further contain at least a portion of the monofunctional (meth)acrylate, or, if necessary, at least a portion of the polyfunctional (meth)acrylate. The dispersant (D) preferably has an acid value in the range of 50 to 300 mgKOH / g. The dispersant (D) generally tends to cause aggregation of inorganic nanoparticles within the system due to interactions between the inorganic particles (A) and other resin components contained in the active energy ray-curable composition according to this embodiment. As a result, the stability of the active energy ray-curable composition during storage may be reduced, and the transparency of the cured coating film may be reduced. By using a dispersant (D) with an acid value in the range of 50 to 300 mgKOH / g, a curable composition with excellent stability over time can be obtained, and the cured product may have not only a high refractive index but also excellent light transmittance and scratch resistance. The inorganic particle (A) dispersion according to this embodiment preferably further contains the silane coupling agent (E) as the additive. Functional groups can be introduced onto the surfaces of the inorganic particles (A) using the various silane coupling agents (E) described above.

[0070] The method for producing the inorganic particle (A) dispersion according to the present embodiment is not particularly limited, and examples thereof include a method for producing the dispersion by dispersing raw materials containing the inorganic particles (A), the dispersant (D), and, if necessary, the silane coupling agent (E) using a media-type wet disperser.

[0071] The media-type wet disperser used in the production method can be any known one without any limitation, and examples thereof include a bead mill (Star Mill LMZ-015 manufactured by Ashizawa Fine Tech Co., Ltd., Ultra Apex Mill UAM-015 manufactured by Kotobuki Industries Co., Ltd., etc.).

[0072] The media used in the disperser are not particularly limited as long as they are commonly known beads, but preferred examples include zirconia, alumina, silica, glass, silicon carbide, and silicon nitride. The average particle size of the media is preferably 50 to 500 μm, and more preferably 50 to 200 μm. If the particle size is 50 μm or more, the impact force on the raw material powder is appropriate, and dispersion does not require an excessive amount of time. On the other hand, if the particle size of the media is 500 μm or less, the impact force on the raw material powder is appropriate, and therefore an increase in the surface energy of the dispersed particles can be suppressed, and reagglomeration can be prevented.

[0073] Alternatively, the dispersion process time can be shortened by a two-stage method in which large-particle-size media with a large impact force are used in the initial stage of grinding the raw material powder, and then small-particle-size media that are less likely to re-agglomerate are used after the particle size of the dispersed particles has become smaller.

[0074] Furthermore, it is desirable to use media that has been sufficiently polished in order to prevent a decrease in the light transmittance of the resulting dispersion.

[0075] In the production method using the media-type wet disperser, the order in which the raw materials are charged into the disperser is not particularly limited, but by supplying at least the dispersant (D) last, a curable composition excellent in dispersion stability can be obtained using a small amount of dispersant (D). More specifically, there can be mentioned a method in which the raw materials other than the dispersant (D) are charged first, and then mixing or pre-dispersion or the like is carried out, and then the dispersant (D) is charged last and the main dispersion step is carried out.

[0076] After dispersion is complete, various additives may be added depending on the intended use, or volatile components may be removed by distillation, thereby obtaining the curable composition of the present invention.

[0077] Furthermore, the particle size (referred to as the average particle size) of the inorganic particles (A) in the inorganic particle (A) dispersion is larger than the average primary particle size of the inorganic particles (A) that are the raw material for the inorganic particle (A) dispersion, because the inorganic particles (A) are partially aggregated in the dispersion. Therefore, the average particle size of the inorganic particles (A) in the inorganic particle (A) dispersion is preferably 100 nm or less, more preferably in the range of 1 to 100 nm, and even more preferably in the range of 20 to 100 nm, in order to produce a cured product with a high refractive index and excellent light transmittance. The particle size is measured by dynamic light scattering.

[0078] [Characteristics of Active Energy Ray-Curable Composition] The active energy ray-curable composition of this embodiment has good self-healing properties, a high refractive index, and a low viscosity. Examples of the active energy ray-curable composition of this embodiment include LUXYDIR (registered trademark) (manufactured by DIC Corporation).

[0079] (Cured Product) The cured product of this embodiment is a cured product of the active energy ray-curable composition of this embodiment described above. The cured product of this embodiment can be used in various applications, such as optical lenses, optical films (shaped optical films), anti-reflection materials, thin-film encapsulating materials, optical pressure-sensitive adhesives, optical adhesives, and diffusion microlenses. The shape of the cured product of this embodiment is not particularly limited, and can be selected depending on the application, such as a flat sheet with a smooth surface, a sheet with a fine uneven structure, or a sheet with a curved surface like a concave or convex lens. The refractive index (589 nm) of the cured product of this embodiment at 25°C is preferably 1.62 or more, more preferably 1.65 or more, and even more preferably 1.66 or more. In this case, when used in optical lenses, it can be made thinner; in optical films, the difference in refractive index with the transparent electrode can be reduced to make the transparent electrode less noticeable; when combined with a low refractive index layer, it can impart anti-reflection functionality; and in LED encapsulants, it can increase the light extraction efficiency from the light-emitting element. The upper limit of the refractive index is not particularly limited, and a higher value is preferable. If anything, it is preferable that the ratio is 1.62 or more and 1.70 or less from the viewpoint of the balance with the viscosity.

[0080] [Method for Producing Cured Product] The method for producing the cured product of this embodiment is not particularly limited, and may include, for example, a coating step of coating the active energy ray-curable composition of this embodiment onto a substrate such as a transparent film, and a curing step of irradiating the film of the active energy ray-curable composition obtained in the coating step with active energy rays to cure it. As a method for coating the substrate such as a transparent film, a known method can be used, and for example, a method using a rod or wire bar, or various coating methods such as microgravure, gravure, die, curtain, lip, slot, or spin can be used.

[0081] The active energy rays can be used without any particular limitation as long as they are active energy rays that cause curing of the curable composition of the present invention, but it is particularly preferable to use ultraviolet rays.

[0082] Sources of ultraviolet rays include fluorescent chemical lamps, black lights, low-pressure, high-pressure, and ultra-high-pressure mercury lamps, metal halide lamps, and sunlight. For example, an 80 W high-pressure mercury lamp can be used. The irradiation intensity of the ultraviolet rays can be kept constant throughout, or the intensity can be changed during curing to finely adjust the physical properties after curing. For example, when an 80 W high-pressure mercury lamp is used in a nitrogen atmosphere, the ultraviolet rays can be irradiated at 0.5 to 3.0 kJ / m ２ It can be irradiated with an energy value of

[0083] In addition to ultraviolet rays, other active energy rays that can be used include visible light and electron beams.

[0084] (Shaped Optical Film) The shaped optical film of this embodiment can be formed using the cured product of this embodiment described above. The shaped optical film of this embodiment may be, for example, the cured product according to this embodiment formed on a substrate. The shaped optical film of this embodiment is, for example, formed by forming a fine pattern such as a fine uneven structure on a cured product of the active energy ray-curable composition of this embodiment. The fine pattern layer such as the fine uneven structure may have a fine uneven structure of 10 to 500 μm on its surface, depending on the application of the optical sheet. Examples of the shaped optical film include polarizing films, retardation films, antireflection films, brightness enhancement films (prism sheets, microlens sheets, etc.), and light diffusion films.

[0085] [Method for manufacturing shaped optical film] The method for manufacturing the shaped optical film of this embodiment is not particularly limited, and includes, for example, a step of applying the active energy ray curable composition of this embodiment to the substrate, a step of shaping the coating film using a mold with a fine pattern shape such as a desired fine uneven structure, and a step of irradiating with active energy rays such as ultraviolet rays to form a cured coating film.

[0086] A method for producing the shaped optical film of this embodiment can be, for example, the method described in Patent Document (JP 2009-37204 A). As shown in Figure 2 of the patent document, the composition is placed in a mold having a fine pattern shape such as a desired fine concave-convex structure, a transparent substrate layer is laminated thereon, the transparent substrate layer is pressed onto the composition using a laminator or the like, and the composition is cured with ultraviolet light or the like to form a fine pattern shape such as a fine concave-convex structure. Next, the mold having the fine pattern shape is peeled or removed to obtain a shaped optical film having an optical function-exhibiting portion having the desired fine pattern shape on the transparent substrate layer.

[0087] (Optical Sheet) The optical sheet of this embodiment can be formed using the cured product of this embodiment. The optical sheet of this embodiment may include, for example, a substrate and the cured product of this embodiment formed on the substrate. The optical sheet of this embodiment may include, for example, a fine pattern layer having a fine unevenness structure, which is a cured product of the active energy ray-curable composition of this embodiment, and a transparent substrate. Furthermore, the fine pattern layer having a fine unevenness structure, for example, may have a fine unevenness structure of 10 to 500 μm on its surface depending on the application of the optical sheet. Furthermore, the cured product of the active energy ray-curable composition in the optical sheet of this embodiment may have a smooth surface without a fine unevenness structure. Appropriate shapes can be selected depending on various applications. Examples of optical sheets include polarizing films, retardation films, antireflection films, brightness-enhancing films (prism sheets, microlens sheets, etc.), light-diffusing films, and hard-coated films.

[0088] [Substrate] Examples of the substrate according to this embodiment include polyethylene terephthalate (PET), triacetyl cellulose (TAC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polycarbonate, vinyl chloride, polymethacrylimide, polyimide, polyester, acrylic substrates mainly composed of polymethyl methacrylate (PMMA), glass, and silicon wafers. The film thickness of the substrate according to this embodiment is preferably 1 to 300 μm, and more preferably 5 to 100 μm. Specific examples of the substrate according to this embodiment include the 125 μm polyethylene terephthalate (PET) substrate (product name: A4300, manufactured by Toyobo Co., Ltd.) used in the examples.

[0089] When the substrate is transparent, a transparent substrate used in a conventional optical sheet such as a prism sheet can be used. For example, the transparent substrate described in Patent Document 2 can be used. The transparent substrate may be a resin substrate or a glass substrate. Preferred transparent resin substrates include acrylic resin, polycarbonate resin, vinyl chloride resin, polymethacrylimide resin, polyimide resin, polyester resin, cycloolefin polymer (COP) resin, cycloolefin copolymer (COC) resin, and cellulose triacetate (TAC) resin.

[0090] The transparent substrate may be in a long shape or in a sheet shape of a predetermined size. The thickness of the transparent substrate is usually preferably 50 to 500 μm, but is not limited thereto. The light transmittance of the transparent substrate is ideally 100% for installation in front of a display, and preferably 85% or more. The surface of the transparent substrate may be subjected to a conventionally known matte treatment (formation of light-diffusing micro-irregularities), antistatic treatment, antireflection treatment, or the like, as necessary. Furthermore, a matte treatment, antistatic treatment, antireflection treatment, or the like may be applied between the transparent resin and the substrate, or these treatments may be used in any combination.

[0091] [Method for Producing Optical Sheet] The method for producing the optical sheet of this embodiment is not particularly limited, and includes, for example, the steps of applying the active energy ray-curable composition of this embodiment to the substrate and irradiating it with active energy rays such as ultraviolet rays to form a cured coating film. A method for producing the laminate of this embodiment, for example, includes the steps of applying the active energy ray-curable composition of this embodiment to a triacetyl cellulose substrate film (TAC substrate film) having a thickness of 40 to 100 μm and irradiating it with ultraviolet rays at 0.5 to 3.0 kJ / m using a 60 to 100 W high-pressure mercury lamp under a nitrogen atmosphere. ２ and forming a cured coating film having a thickness of 5 to 20 μm on the TAC substrate film.

[0092] An example of a method for producing the optical sheet of this embodiment is the method described in Patent Document (JP 2009-37204 A). As shown in Figure 2 of the patent document, the composition is placed in a mold having a fine pattern shape such as a desired fine concavo-convex structure, a transparent substrate layer is laminated thereon, the transparent substrate layer is pressed onto the composition using a laminator or the like, and the composition is cured with ultraviolet light or the like to form a fine pattern shape such as a fine concavo-convex structure. Next, the fine pattern shape mold is peeled or removed to obtain an optical sheet having an optical function-exhibiting portion having the desired fine pattern shape on the transparent substrate layer.

[0093] <Prism Sheet> A specific example of the optical sheet of this embodiment is a prism sheet. The prism sheet has, for example, a microrelief structure layer that is a cured product of the active energy ray-curable composition of this embodiment, and a transparent substrate. The microrelief structure layer has a microrelief structure with a period P of 10 to 100 μm on its surface. The thickness of the microrelief structure layer is, for example, 5 μm to 100 μm.

[0094] Typically, when the content of monofunctional (meth)acrylate in a composition is high, the polymer structure after curing tends to have less branching, resulting in poor self-healing properties of the cured product. Focusing on this tendency, the present invention has been able to improve self-healing properties by setting the mass ratio [(A) / (B)] of the monofunctional (meth)acrylate to the inorganic particles (A) to a range of 0.5 to 3. More specifically, when [(A) / (B)] is in the range of 0.5 to 3, the inorganic particles (A) are more likely to be present on the surface (i.e., near the interface between the composition and the mold) when the composition is applied to a substrate, which is thought to reduce adhesion of the cured product of the composition to the mold. Furthermore, the self-healing properties of the cured product can be further improved by including a silane coupling agent and a phosphate ester-based dispersant containing a (meth)acryloyl group in the composition. This is thought to be because the inorganic particles (A) are compatible with the components other than (A) in the composition via the silane coupling agent and phosphate ester-based dispersant, thereby increasing the strength of the cured product and making it less likely for the cured product to remain on the mold when the cured product is peeled from the mold. Furthermore, in the present invention, substrate adhesion was particularly improved when orthophenylphenol (EO) acrylate, biphenyl methyl acrylate, or (1-naphthyl)methyl acrylate was used as the monofunctional (meth)acrylate. These compounds are monomers with relatively high glass transition temperatures, and it is thought that they also improve the coating hardness of the composition. It is possible that this improved hardness and several other factors combined to improve substrate adhesion. In addition, substrate adhesion was also good when phenoxyethyl acrylate was used as the monofunctional (meth)acrylate. This is thought to be because phenoxyethyl acrylate contains a highly polar ethylene oxide structure in its molecule, which enhances its interaction with the substrate. As described above, configurations that provide greater effects and the mechanisms by which these effects are thought to be manifested have been explained, but the present invention is not limited to these configurations, and the problems of the present invention can also be solved with compositions that do not contain a silane coupling agent or a phosphate ester-based dispersant, or compositions that do not contain a specific compound as a monofunctional (meth)acrylate.

[0095] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. (Raw Materials) "Zirconia (A)": UEP-100 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) "Dispersant (1)" (phosphate ester compound): a compound represented by the following structural formula (1)

[0096]

[0097] (In the formula, R １ is a methyl group, and R ２ is an ethylene chain having 2 carbon atoms, x is 5, y is 2 (average value), and n is an integer from 1 to 3.

[0098] "Silane coupling agent (E)": KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd., 3-(trimethoxysilyl)propyl methacrylate)

[0099] "Monofunctional (meth)acrylate compound (B1)": orthophenylphenol (EO) acrylate, trade name: KOMERATE A011 (manufactured by Green Chemical Co., Ltd.) Phenoxyethyl acrylate, trade name: Photomer 4035 (manufactured by IGM Resins Inc.) Benzyl acrylate, trade name: MIRAMER M1182 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Phenol EO-modified (n≈2) acrylate, trade name: MIRAMER M142 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Phenol EO-modified (n≈4) acrylate, trade name: MIRAMER M144 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) SPECIALTY CHEMICAL CO., LTD.) Biphenyl methyl acrylate, trade name: MIRAMER M1192 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Acryloyl morpholine, trade name: ACMO (manufactured by KJ Chemicals Co., Ltd.) Polycaprolactone-modified (n≒5) hydroxyethyl acrylate, trade name: PLACCEL FA5 (manufactured by Daicel Chemical Industries, Ltd.) Polycaprolactone-modified (n≒1) hydroxyethyl acrylate, trade name: PLACCEL FA1DDM (manufactured by Daicel Chemical Industries, Ltd.) Phenoxybenzyl acrylate, trade name: KOMERATE A008 (manufactured by Green Chemical Co., Ltd.) Stearyl acrylate, trade name: MIRAMER M180 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.)

[0100] "Polyfunctional (meth)acrylate compounds" Dipentaerythritol EO-modified (n≈24) hexaacrylate, trade name: KOMERATE M246 (manufactured by Green Chemical Co., Ltd.) Bisphenol A EO-modified (n≈6) diacrylate, trade name: MIRAMER M244 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Bisphenol fluorene EO-modified (n≈6) diacrylate, trade name: KOMERATE D064 (manufactured by Green Chemical Co., Ltd.) Bisphenol fluorene EO-modified (n≈20) diacrylate, trade name: KOMERATE D204 (manufactured by Green Chemical Co., Ltd.) Co., Ltd.) Bisphenol A EO-modified (n≈10) diacrylate, trade name: MIRAMER M2100 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Trimethylolpropane EO-modified (n≈3) triacrylate, trade name: MIRAMER M3130 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Trimethylolpropane EO-modified (n≈6) triacrylate, trade name: MIRAMER M3160 (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (containing approximately 60% of triacrylate), trade name: ARONIX M-305 (manufactured by Toagosei Co., Ltd.) Dipentaerythritol EO-modified (n≒13) hexaacrylate, trade name: KOMERATE M136 (manufactured by Green Chemical Co., Ltd.)

[0101] "Photopolymerization initiator (C)": 1-hydroxycyclohexyl phenyl ketone, trade name: Runtecure 1104 (manufactured by Runtec Chemical Co., Ltd.) 2,4,6-trimethylbenzoyldiphenylphosphine oxide, trade name: Runtecure 1108 (manufactured by Runtec Chemical Co., Ltd.)

[0102] <Liquid Refractive Index> The active energy ray-curable composition was directly applied to the prism of an Abbe refractometer, and measurement was carried out at 25° C. Measurement wavelength: 589 nm.

[0103] <Viscosity> The viscosity was measured at a temperature of 25°C using an E-type rotational viscometer ("TVE-25H" manufactured by Toki Sangyo Co., Ltd.).

[0104] <Self-healing property> The active energy ray-curable resin composition was filled between a mold on which a linearly arranged concave-convex shape of unit prisms (pitch 50 μm, height 25 μm) was formed and a transparent, easily adhesive PET film (product name: A4300, thickness: 125 μm, manufactured by Toyobo Co., Ltd.) as a transparent substrate. Thereafter, the active energy ray-curable resin composition was irradiated with 400 mJ / cm 2 of an ultra-high pressure mercury lamp. ２ The PET film was cured by irradiating it with ultraviolet light from the PET film side. Next, the PET film was peeled off from the mold together with the active energy ray-curable resin layer, and a shaped PET film was produced by transferring the required shape. The shaped PET film was attached to a movable platen manufactured by Imoto Machinery Works, with the top of the shaped cured product facing the load section. A diffusion film was attached to a 1 cm diameter holder as an abrasion element on the load section side, and the base layer of the diffusion film was placed so that it rubbed against the top of the shaped cured product. Evaluation was carried out indoors at a temperature of 23°C and a humidity of 50%. A 300 g load was applied to the load section and the abrasion resistance tester was operated. The movable platen was moved once in one direction (movement speed: 4 m / min, movement distance: 10 cm). The degree of band-like scratches was evaluated visually, and the results were judged as follows, with A to B being considered pass. A: Wounds heal instantly. B: Wounds heal within 10 seconds. C: Wounds heal within 30 seconds. D: Wounds do not heal even after 30 seconds.

[0105] <Martens Hardness (HM) and Elastic Deformation Power (nIT)> The active energy ray-curable resin composition was filled between two glass plates using a 125 μm-thick PET film as a spacer. Then, the active energy ray-curable resin composition was irradiated with 400 mJ / cm 2 of an ultra-high pressure mercury lamp. ２The coating was cured by irradiating it with ultraviolet light of 1000 W at 1000 W. Next, the glass plate opposite the irradiated surface was peeled off, and a flat film-like cured product with a thickness of 125 μm was produced on the glass plate. The Martens hardness (HM) and elastic deformation power (nIT) of the produced flat film were measured using a microhardness tester (trade name HM2000) manufactured by Fischer Instruments Co., Ltd. in accordance with ISO 14577-1. The test conditions were as follows: Indenter: Vickers indenter F: 30 mN / 5 s C: 5.0 s R: 0.1 mN / 5 s C2: 10.0 s

[0106] The Martens hardness (HM) was calculated using the following formula (in the case of a Vickers indenter): Martens hardness (unit: N / mm ２ ) = Test load F / 26.43 × {(Indentation depth after holding maximum test force h ２ )^2}

[0107] The elastic deformation power (nIT) was calculated using the following formula: Elastic deformation power (unit: %) = W ｅｌａｓｔ / (W ｅｌａｓｔ +W ｐｌａｓｔ ) x 100

[0108] 1 is a diagram illustrating a method for measuring the elastic deformation power. In the formulas for the Martens hardness and the elastic deformation power, the test load (test force) F, the indentation depth after holding the maximum test force h, ２ , elastic deformation work W ｅｌａｓｔ , plastic deformation work W ｐｌａｓｔ The relationship is shown in Figure 1.

[0109] Example 1 55.00 parts by mass of UEP-100 as zirconia, 3.2 parts by mass of a phosphate ester (dispersant (1)) represented by the above structural formula (1) as a phosphate ester, 9.5 parts by mass of KBM-503 as a silane coupling agent (1), and 110 parts by mass of methyl ethyl ketone (hereinafter abbreviated as "MEK") were mixed and stirred for 30 minutes with a dispersion stirrer to perform coarse dispersion. The resulting mixture was then dispersed using zirconia beads with a particle size of 100 μm in a media-type wet disperser ("Star Mill LMZ-015" manufactured by Ashizawa Finetech Co., Ltd.). The dispersion process was continued for a residence time of 100 minutes while checking the particle size during the process, and an inorganic particle dispersion was obtained. To this inorganic particle dispersion, 2.3 parts by mass of KOMERATE A011, 18.3 parts by mass of Photomer 4035, 3.8 parts by mass of MIRAMER M1192, 4.4 parts by mass of ACMO, and 1.5 parts by mass of MIRAMER M2100 were added, and the mixture was heated in an evaporator to remove volatile components under reduced pressure. Furthermore, 1.0 part by mass of Runtecure 1104 (manufactured by Runtec Chemical Co., Ltd.) and 1.0 part by mass of Runtecure 1108 (manufactured by Runtec Chemical Co., Ltd.) were added as photopolymerization initiators to prepare an active energy ray-curable composition P1 (composition P1) of this embodiment. The liquid refractive index and viscosity of Composition P1 were evaluated using the above evaluation methods. Furthermore, the Martens hardness (HM), elastic deformation power (nIT), and self-healing property of the cured product of Composition P1 were evaluated. The results are shown in Table 1.

[0110] (Examples 2 to 15, Comparative Examples 1 to 15) Compositions P2 to P14 and cP1 to cP6 of Examples 2 to 14 and Comparative Examples 1 to 6 were prepared in the same manner as Example 1, except that the components and compositional ratios shown in Table 1 were used. As in Example 1, the amount of MEK used was 2.15 times the amount of inorganic particles shown in Table 1. As in Example 1, the liquid refractive index, film refractive index, and viscosity of each composition were evaluated. In addition, the Martens hardness (HM), elastic deformation power (nIT), and self-healing property of the cured product of each composition were evaluated. The results are shown in Tables 1 to 4.

[0111]

[0112]

[0113]

[0114]

[0115] In Tables 1 to 4, the meanings of each description are as follows: UEP-100: Zirconia (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) Dispersant (1): Phosphate ester represented by the following structural formula (1)

[0116]

[0117] KBM-503: 3-(trimethoxysilyl)propyl methacrylate (manufactured by Shin-Etsu Chemical Co., Ltd.) KOMERATE A011: orthophenylphenol (EO) acrylate (manufactured by Green Chemical Co., Ltd.) Photomer 4035: phenoxyethyl acrylate (manufactured by IGM Resins Inc.) MIRAMER M1182: benzyl acrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) MIRAMER M142: phenol EO-modified (n≈2) acrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) MIRAMER M144: Phenol EO-modified (n≒4) acrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) MIRAMER M1192: Biphenyl methyl acrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) ACMO: Acryloyl morpholine (manufactured by KJ Chemicals Co., Ltd.) PLACCEL FA5: Polycaprolactone-modified (n≒5) hydroxyethyl acrylate (manufactured by Daicel Chemical Industries, Ltd.) PLACCEL FA1DDM: Polycaprolactone-modified (n≒1) hydroxyethyl acrylate (manufactured by Daicel Chemical Industries, Ltd.) KOMERATE A008: Phenoxybenzyl acrylate (manufactured by Green Chemical Co., Ltd.) MIRAMER M180: Stearyl acrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) KOMERATE M246: Dipentaerythritol EO-modified (n≈24) hexaacrylate (manufactured by Green Chemical Co., Ltd.) MIRAMER M244: Bisphenol A EO-modified (n≈6) diacrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) KOMERATE D064: Bisphenol fluorene EO-modified (n≈6) diacrylate (manufactured by Green Chemical Co., Ltd.) KOMERATE D204: Bisphenol fluorene EO-modified (n≈20) diacrylate (Green Chemical Co.,Ltd. MIRAMER M2100: Bisphenol A EO-modified (n≈10) diacrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) MIRAMER M3130: Trimethylolpropane EO-modified (n≈3) triacrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) MIRAMER M3160: Trimethylolpropane EO-modified (n≈6) triacrylate (manufactured by MIWON SPECIALTY CHEMICAL CO., LTD.) ARONIX M-305: Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (containing approximately 60% of triacrylate) (manufactured by Toagosei Co., Ltd.) KOMERATE M136: Dipentaerythritol EO-modified (n≈13) hexaacrylate (manufactured by Green Chemical Co., Ltd.) Runtecure 1104: 1-hydroxycyclohexyl phenyl ketone (manufactured by Runtec Chemical Co., Ltd.) Runtecure 1108: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by Runtec Chemical Co., Ltd.),

[0118] NdCH2: number of unsaturated double bonds RotRatio: ratio of rotatable bonds ARR: ratio of rotatable bonds HM_N / mm ２ Martens hardness (= test load F / 26.43 × {(indentation depth h after holding the maximum test force)} ２ )^2}) (unit: N / mm ２ ) *In the case of a Vickers indenter nIT_%: Elastic deformation power (= W ｅｌａｓｔ / (W ｅｌａｓｔ +W ｐｌａｓｔ ) x 100) (unit: %)

[0119] (Discussion) As shown in Tables 1 to 4, by setting the content of inorganic particles, parameter NdCH2, parameter RotRatio, and parameter ARR within a predetermined range, it was possible to achieve both good self-healing properties, low viscosity, and high refractive index. Furthermore, by setting these parameters within particularly preferred ranges, an even better balance of physical properties was achieved (Examples 1 and 2). Focusing on the parameter RotRatio, when other parameters were the same, the refractive index decreased as the parameter RotRatio increased. This is because the rotatable bond is a single bond, so the electron density is low and molecules containing rotatable bonds have a low refractive index. The self-healing properties improved as the parameter RotRatio increased. Furthermore, the Martens hardness (HM) decreased and the elastic deformation power (nIT) increased. This is thought to be because the rotatable bond has high mobility and therefore maintains its bonded state without breaking even during deformation. Focusing on the parameter NdCH2, when other parameters were the same, the Martens hardness (HM) increased as the parameter NdCH2 increased. In addition, the elastic deformation power (nIT) decreased. This is because the concentration of double bonds contributing to polymerization increased, resulting in an increase in cross-linking points. Focusing on the content of inorganic particles, when other parameters were the same, the viscosity increased as the content of inorganic particles increased. This is because the interaction between particles contributes to viscosity.

[0120] F: Test force h: Indentation depth W ｅｌａｓｔ Elastic deformation work W ｐｌａｓｔ Plastic deformation work h １ Indentation depth at maximum test force h ２ Indentation depth after holding maximum test force h ｍａｘ Maximum Push-in Depth

Claims

1. An active energy ray-curable composition comprising inorganic particles (A), a (meth)acrylate compound (B), a photopolymerization initiator (C), and a dispersant (D), The inorganic particles (A) are zirconia, The (meth)acrylate compound (B) contains a biphenyl structure, the content of the inorganic particles (A) in the active energy ray-curable composition is 30% by mass or more and 60% by mass or less, the value of a parameter NdCH2 generated from the active energy ray-curable composition is 1.0 to 4.0; a value of a parameter RotRatio generated from the composition of the active energy ray-curable composition is 0.2 to 0.85; The active energy ray-curable composition has a parameter ARR value of 0.71 to 1.3, the parameter ARR being determined from the composition of the active energy ray-curable composition. The parameter NdCH2 is a value calculated using NdCH2 (compound) of each component contained in the active energy ray-curable composition, and the NdCH2 (compound) is a parameter calculated by the following formula (1). NdCH2 (compound) = number of unsaturated double bonds / 1 molecule (1) The parameter RotRatio is a value calculated using the RotRatio (compound) of each component contained in the active energy ray-curable composition, and the RotRatio (compound) is a parameter calculated by the following formula (2). RotRatio = number of rotatable bonds / total number of bonds (2) The parameter ARR is a value calculated using the ARR (compound) of each component contained in the active energy ray-curable composition, and the ARR (compound) is a parameter calculated by the following formula (3). ARR = number of aromatic bonds / total number of bonds (3)

2. The active energy ray curable composition described in claim 1, wherein the dispersant (D) contains a phosphate ester and the phosphate ester has a (meth)acryloyl group.

3. 3. The active energy ray-curable composition according to claim 1, wherein the inorganic particles (A) have a particle size of 1 to 100 nm as measured by a dynamic light scattering method.

4. The active energy ray-curable composition according to claim 1 or 2, wherein the (meth)acrylate compound (B) contains biphenylmethyl (meth)acrylate.

5. The active energy ray-curable composition according to claim 1 or 2, which is used for a shaped optical film.

6. A cured product of the active energy ray-curable composition according to claim 1 or 2.

7. A shaped optical film comprising the cured product according to claim 6.

8. An optical sheet comprising the cured product according to claim 6 .