Photocurable resin composition, cured product, optical molded product, and optical device

Abstract

Provided is a photocurable resin composition that can be used in an optical molded product, wherein the photocurable resin composition comprises a (meth) acrylate monomer with two or more functional groups, that contains one or more selected from the group consisting of an alicyclic bifunctional (meth) acrylate monomer and a linear bifunctional (meth) acrylate monomer, wherein the total content of the (meth) acrylate monomer with two or more functional groups of the alicyclic bifunctional (meth) acrylate monomer and the linear bifunctional (meth) acrylate monomer is 60-100 parts by mass, inclusive, when the total content of the (meth) acrylate monomer with two or more functional groups is 100 parts by mass.

Description

Photocurable resin composition, cured product, optical molded body, and optical device

[0001] The present invention relates to a photocurable resin composition, a cured product, an optical molded body, and an optical device.

[0002] In recent years, thermoplastic resins and ultraviolet-curable resin compositions have been studied in the field of optical lenses from the viewpoints of heat resistance and low birefringence. Among these, methacrylic resin compositions, which are thermoplastic resins, have been studied. For example, techniques for methacrylic resin compositions are described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes an object of providing a methacrylic resin composition that has high heat resistance, highly controlled birefringence, high light transmittance over a long optical path, and excellent color tone and transparency. The composition contains a methacrylic resin that contains at least a structural unit derived from an N-substituted maleimide monomer in the main chain, and has a glass transition temperature of more than 120°C and 160°C or less, and a shear rate of 1000 sec at a resin temperature of 270°C. ―１ The melt viscosity under the condition of is 250 Pa sec or less, and the absolute value of the photoelastic coefficient is 1×10 ―１２ pa ―１ The document describes a methacrylic resin composition, which has a light transmittance of 94% or more when measured under conditions of an optical path length of 100 mm and a wavelength of 470 nm, and a light transmittance of 96% or more when measured under conditions of a wavelength of 700 nm, when the resin composition is dissolved in chloroform at a mass to volume ratio of 20%.

[0004] Patent Document 2 describes a photocurable composition that is fast-curing, non-anaerobic, low-viscosity, low-odor, and has excellent storage stability, and in particular, that provides a cured product that is excellent in various properties required for lenses, such as colorless transparency, low optical distortion, heat resistance, low water absorption, toughness, and high hardness. The photocurable composition contains a tricyclodecane-skeleton di(meth)acrylate (A), a trifunctional or tetrafunctional secondary thiol (B), a cleavage-type photopolymerization initiator (C), and a hindered phenol-based antioxidant (D), and is characterized in that the photocurable composition does not contain a primary thiol, and the content ratio (weight ratio) of components (A), (B), (C), and (D) is within the following range: Component (A) / Component (B) = 75 / 25 to 95 / 5 Component (C): 2 to 10 parts by weight per 100 parts by weight of the total of Components (A) and (B) Component (D): 0.1 to 1 part by weight per 100 parts by weight of the total of Components (A) and (B)

[0005] JP 2019-35015 A JP 2022-32186 A

[0006] The present invention provides a photocurable resin composition capable of reducing the in-plane retardation of an optical molded article.

[0007] The present inventors conducted extensive research to achieve the above-mentioned object. As a result, they found that the type of difunctional or higher functional (meth)acrylate monomer contained in a photocurable resin composition is related to the in-plane retardation Re of the resulting optical molded body. Based on the above findings, the present inventors conducted further extensive research and found that the in-plane retardation Re of the resulting optical molded body can be reduced by using a photocurable resin composition in which the total content of alicyclic bifunctional (meth)acrylate monomers and linear bifunctional (meth)acrylate monomers is 60 parts by mass or more and 100 parts by mass or less, when the total content of difunctional or higher functional (meth)acrylate monomers is 100 parts by mass, thereby completing the present invention.

[0008] [1] A photocurable resin composition that can be used for an optical molded body, comprising a difunctional or higher functional (meth)acrylate monomer including one or more selected from the group consisting of an alicyclic difunctional (meth)acrylate monomer and a linear difunctional (meth)acrylate monomer, wherein the total content of the difunctional or higher functional (meth)acrylate monomer is 100 parts by mass, and the total content of the alicyclic difunctional (meth)acrylate monomer and the linear difunctional (meth)acrylate monomer is 60 parts by mass or more and 100 parts by mass or less. [2] The photocurable resin composition according to [1], comprising one or more monomers selected from the group consisting of a monofunctional (meth)acrylate monomer and the difunctional or higher functional (meth)acrylate monomer, wherein the content of the difunctional or higher functional (meth)acrylate monomer is 5.0 parts by mass or more and 90 parts by mass or less, when the total content of the monofunctional (meth)acrylate monomer and the difunctional or higher functional (meth)acrylate monomer is 100 parts by mass. [3] The photocurable resin composition according to [2], comprising the monofunctional (meth)acrylate monomer. [4] The photocurable resin composition according to [2] or [3], wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton. [5] The photocurable resin composition according to any one of [1] to [4], wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> below has an in-plane retardation Re of 50.0 nm or less, as measured according to the <Measurement of In-Plane Retardation> below.<Conditions for Producing Cured Film> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet. The circular hole was filled with the photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet was placed on top of the silicone-free glass sheet. The height was adjusted by placing this on a stainless steel lab jack. The photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW from above the alkali-free glass sheet for 3 minutes, then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass sheet was then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was released from the alkali-free glass sheet and the silicone sheet to obtain a cured film of the photocurable resin composition. <Measurement of In-Plane Retardation> One hour after completion of the LED light irradiation, the in-plane retardation Re of the cured film is measured using a two-dimensional birefringence evaluation device at a distance of 10.0 mm from the center of the cured film in air at an ambient temperature of 23° C. [6] The photocurable resin composition according to any one of items [1] to [5], wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> below is subjected to the <Heat Treatment> below, and the in-plane retardation Re after heating is measured according to the <Measurement of In-Plane Retardation after Heat Treatment> below, and is 16.0 nm or less. <Conditions for Producing Cured Film> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet. The circular hole was filled with the photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet was placed on top of the silicone-free glass sheet. The height was adjusted by placing this on a stainless steel lab jack. The photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW from above the alkali-free glass sheet for 3 minutes, then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass sheet was then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was released from the alkali-free glass sheet and the silicone sheet to obtain a cured film of the photocurable resin composition.<Heat Treatment> The cured film is heated from 23°C to 120°C at a uniform rate over 1 hour, heated at 120°C for 1 hour, cooled from 120°C to 23°C at a uniform rate over 3 hours, and then cooled at 23°C for 3 hours. <Measurement of In-Plane Retardation after Heat Treatment> One hour after the completion of the <Heat Treatment>, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film using a two-dimensional birefringence evaluation device in air at an ambient temperature of 23°C. [7] The photocurable resin composition according to any one of [1] to [6] above, further comprising an antioxidant. [8] The photocurable resin composition according to any one of [1] to [7] above, further comprising a photopolymerization initiator. [9] The photocurable resin composition according to [8] above, wherein the photopolymerization initiator comprises a photoradical polymerization initiator.

[10] The photocurable resin composition according to any one of [1] to [9] above, further comprising a light stabilizer.

[11] The photocurable resin composition according to any one of [1] to

[10] above, which can be used in a casting method.

[12] The photocurable resin composition according to any one of [1] to

[11] above, which can be used for one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

[13] A cured product of the photocurable resin composition according to any one of [1] to

[12] above.

[14] An optical molded article comprising a cured product of the photocurable resin composition according to any one of [1] to

[12] above.

[15] The optical molded article according to

[14] above, which comprises a lens.

[16] The optical molded body according to

[15] , wherein the lens comprises one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

[17] The optical molded body according to any one of

[14] to

[16] , wherein the maximum thickness portion is 20.0 mm or less.

[18] The optical molded body according to any one of

[14] to

[17] , wherein the maximum thickness is 1.0 mm or more.

[19] An optical device comprising the optical molded body according to any one of

[14] to

[18] .

[0009] According to the present invention, it is possible to provide a photocurable resin composition capable of reducing the in-plane retardation of an optical molded product.

[0010] In this specification, the term "(meth)acrylate" represents a concept that encompasses both acrylate and methacrylate. The same applies to similar terms such as "(meth)acryloyl." For each component of this embodiment, one type may be used, or two or more types may be used in combination. Furthermore, the term "to" representing a numerical range means "greater than or equal to" or "less than or equal to," and includes both the upper and lower limits.

[0011] (Photocurable Resin Composition) The photocurable resin composition of this embodiment (hereinafter also referred to simply as "resin composition") is a photocurable resin composition that can be used for optical molded bodies, and contains one or more difunctional or higher (meth)acrylate monomers (A2) selected from the group consisting of alicyclic bifunctional (meth)acrylate monomers and linear bifunctional (meth)acrylate monomers. When the total content of the difunctional or higher (meth)acrylate monomers (A2) is 100 parts by mass, the total content of the difunctional or higher (meth)acrylate monomers of the alicyclic bifunctional (meth)acrylate monomer and the linear bifunctional (meth)acrylate monomer is 60 parts by mass or more and 100 parts by mass or less. By having the above-mentioned configuration, the photocurable resin composition of this embodiment can reduce the in-plane retardation of the optical molded body.

[0012] The photocurable resin composition includes a polymerizable compound. The polymerizable compound includes a difunctional or higher functional (meth)acrylate monomer (A2) from the viewpoint of reducing coloration of the optical molded body. The difunctional or higher functional (meth)acrylate monomer (A2) includes one or more monomers selected from the group consisting of alicyclic difunctional (meth)acrylate monomers and linear difunctional (meth)acrylate monomers.

[0013] The properties of the photocurable resin composition are not particularly limited. However, from the viewpoint of suitability for forming an optical molded body by molding using an injection method or molding using a cast method, the photocurable resin composition is preferably in a liquid state. Furthermore, from the viewpoint of improving the degree of freedom in designing the optical molded body, the photocurable resin composition is preferably used for molding using a cast method.

[0014] Next, the components of the photocurable resin composition will be described with specific examples. The photocurable resin composition may be composed of a polymerizable compound, or may contain components other than the polymerizable compound. Specific examples of other components of the photocurable resin composition may include one or more selected from the group consisting of an antioxidant (B), a photopolymerization initiator (C), and a light stabilizer (D), which will be described later.

[0015] The di- or higher functional (meth)acrylate monomer (A2) preferably contains a di- or higher functional methacrylate monomer, from the viewpoint of further reducing the in-plane retardation of the optical molded body.

[0016] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the polymerizable compound preferably contains a monofunctional (meth)acrylate monomer (A1), and more preferably contains a monofunctional methacrylate monomer.

[0017] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the content of the difunctional or higher (meth)acrylate monomer (A2) in the photocurable resin composition of this embodiment is preferably 5.0 parts by mass or more and 90 parts by mass or less, more preferably 10 parts by mass or more and 70 parts by mass or less, even more preferably 12 parts by mass or more and 50 parts by mass or less, even more preferably 15 parts by mass or more and 40 parts by mass or less, and even more preferably 18 parts by mass or more and 35 parts by mass or less, when the total content of the monofunctional (meth)acrylate monomer (A1) and the difunctional or higher (meth)acrylate monomer (A2) is taken as 100 parts by mass.

[0018] In the photocurable resin composition of this embodiment, the mass ratio of the content of the monofunctional (meth)acrylate monomer (A1) to the content of the difunctional or higher functional (meth)acrylate monomer (A2) is preferably 0.50 or more and 10.0 or less, more preferably 1.00 or more and 8.00 or less, even more preferably 1.50 or more and 6.00 or less, even more preferably 1.80 or more and 5.00 or less, and even more preferably 2.00 or more and 4.50 or less, from the viewpoint of further reducing the in-plane retardation of the optical molded body.

[0019] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the total content of the (meth)acrylate monomers (A) excluding the (meth)acrylate monomer (A) having an aromatic ring in the photocurable resin composition of this embodiment is, when the total content of the (meth)acrylate monomers (A) is taken as 100 parts by mass, preferably 60 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 100 parts by mass or less, even more preferably 80 parts by mass or more and 100 parts by mass or less, even more preferably 85 parts by mass or more and 100 parts by mass or less, even more preferably 90 parts by mass or more and 100 parts by mass or less, and even more preferably 95 parts by mass or more and 100 parts by mass or less.

[0020] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the total content of the (meth)acrylate monomers (A) excluding the (meth)acrylate monomer (A) having a branched chain in the photocurable resin composition of this embodiment is preferably 60 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 100 parts by mass or less, even more preferably 80 parts by mass or more and 100 parts by mass or less, even more preferably 85 parts by mass or more and 100 parts by mass or less, even more preferably 90 parts by mass or more and 100 parts by mass or less, and even more preferably 95 parts by mass or more and 100 parts by mass or less, when the total content of the (meth)acrylate monomers (A) is taken as 100 parts by mass.

[0021] In the photocurable resin composition of this embodiment, the total content of the monofunctional (meth)acrylate monomers (A1) excluding the aromatic ring monofunctional (meth)acrylate monomer is, when the total content of the (meth)acrylate monomers (A) is taken as 100 parts by mass, preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 30 parts by mass or more and 95 parts by mass or less, even more preferably 40 parts by mass or more and 90 parts by mass or less, even more preferably 50 parts by mass or more and 90 parts by mass or less, and even more preferably 60 parts by mass or more and 90 parts by mass or less, from the viewpoint of being able to further reduce the in-plane retardation of the optical molded body.

[0022] <Monofunctional (meth)acrylate Monomer (A1)> The monofunctional (meth)acrylate monomer (A1) includes, for example, one or more monomers selected from the group consisting of chain monofunctional (meth)acrylates such as aromatic ring monofunctional (meth)acrylates; alicyclic monofunctional (meth)acrylates; linear monofunctional (meth)acrylates (including, for example, monofunctional (meth)acrylate monomers having a linear hydrocarbon skeleton) and branched monofunctional (meth)acrylates.

[0023] The monofunctional (meth)acrylate monomer (A1) is preferably isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate (e.g., GM81HDA, manufactured by Kokusei Chemical Co., Ltd.), 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate (e.g., FA-511AS, manufactured by Hitachi Chemical Co., Ltd.), dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, methyl ... Acrylate, 4-hydroxybutyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isooctyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydixylethyl (meth)acrylate, ethyl Diglycol (meth)acrylate, cyclic trimethylolpropane formal mono(meth)acrylate, imide (meth)acrylate, isoamyl (meth)acrylate, ethoxylated succinic acid (meth)acrylate, trifluoroethyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, cyclohexyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate (e.g., S-1800A, Shin-Nakamura Chemical Co., Ltd.) manufactured by Osaka Organic Chemical Industry Co., Ltd.), diethylene glycol monobutyl ether (meth)acrylate, lauryl (meth)acrylate (e.g., LA, manufactured by Osaka Organic Chemical Industry Co., Ltd.), isodecyl (meth)acrylate, octyl / decyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate, ethoxylated (4) nonylphenol (meth)acrylate, methoxypolyethylene glycol (350) mono(meth)acrylate, methoxypolyethylene glycol (550) mono(meth)acrylate, phenoxyethyl (meth)acrylate,Benzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, tribromophenyl (meth)acrylate, ethoxylated tribromophenyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, ethylene oxide adduct of 2-phenoxyethyl (meth)acrylate, propylene oxide adduct of 2-phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-methacryloyloxymethyl cyclohexene oxide, 3-(meth)acryloyloxymethyl cyclohexene oxide, ethoxylated-o-phenylphenol (meth)acrylate (for example, A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.), 2-methacryloyloxy-2-methyladamantane, and 2-methacryloyloxy-2-ethyladamantane.

[0024] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the monofunctional (meth)acrylate monomer (A1) more preferably includes one or more monomers selected from the group consisting of lauryl (meth)acrylate and dicyclopentanyl (meth)acrylate.

[0025] The monofunctional (meth)acrylate monomer (A1) preferably has an alicyclic skeleton, from the viewpoint of further reducing the in-plane retardation of the optical molded body. The monofunctional (meth)acrylate monomer (A1) more preferably contains dicyclopentanyl (meth)acrylate, and even more preferably contains dicyclopentanyl methacrylate, from the viewpoint of further reducing the in-plane retardation of the optical molded body.

[0026] <Difunctional or higher (meth)acrylate monomer (A2)> From the viewpoint of being able to reduce the in-plane retardation of the optical molded body, the difunctional or higher (meth)acrylate monomer (A2) includes one or more selected from the group consisting of alicyclic bifunctional (meth)acrylate monomers and linear bifunctional (meth)acrylate monomers. From the viewpoint of being able to further reduce the in-plane retardation of the optical molded body, the difunctional or higher methacrylate monomer (A2) preferably includes one or more selected from the group consisting of alicyclic bifunctional methacrylate monomers and linear bifunctional methacrylate monomers.

[0027] From the viewpoint of reducing the in-plane retardation of the optical molded body, the total content of the alicyclic bifunctional (meth)acrylate monomer and the linear bifunctional (meth)acrylate monomer in the photocurable resin composition of this embodiment is 60 parts by mass or more and 100 parts by mass or less, preferably 70 parts by mass or more and 100 parts by mass or less, more preferably 80 parts by mass or more and 100 parts by mass or less, even more preferably 85 parts by mass or more and 100 parts by mass or less, still more preferably 90 parts by mass or more and 100 parts by mass or less, and still more preferably 95 parts by mass or more and 100 parts by mass or less, when the total content of the bifunctional or higher (meth)acrylate monomer (A2) is taken as 100 parts by mass.

[0028] The alicyclic bifunctional (meth)acrylate monomer is a bifunctional (meth)acrylate monomer having an alicyclic hydrocarbon structure in its molecular structure. From the viewpoint of improving heat resistance, the number of carbon atoms in the alicyclic hydrocarbon structure is preferably 4 or more and 14 or less, more preferably 5 or more and 12 or less, and even more preferably 6 or more and 10 or less. The alicyclic hydrocarbon structure may be a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. From the viewpoint of improving heat resistance, the alicyclic hydrocarbon structure is preferably a saturated hydrocarbon structure.

[0029] The alicyclic hydrocarbon structure may be a monocyclic hydrocarbon structure, or a polycyclic hydrocarbon structure such as a fused ring hydrocarbon structure or a bridged ring hydrocarbon structure. The alicyclic bifunctional (meth)acrylate monomer may contain a group containing such an alicyclic hydrocarbon structure in its molecular structure, and preferably contains a divalent group containing an alicyclic hydrocarbon structure. Specific examples of the monocyclic hydrocarbon group include groups having a cycloalkane structure such as a cyclohexylene group or a cyclohexyl group; and groups having a cycloalkene skeleton such as a cyclodecatriene diyl group or a cyclodecatriene group. Specific examples of the polycyclic hydrocarbon group include groups having a dicyclopentadiene skeleton such as a tricyclodecanediyl group, a dicyclopentanyl group, or a dicyclopentenyl group; groups having a norbornane skeleton such as a norbornanediyl group, an isobornanediyl group, a norbornyl group, or an isobornyl group; and groups having an adamantane skeleton such as an adamantanediyl group or an adamantyl group.

[0030] The cyclic hydrocarbon group in the alicyclic bifunctional (meth)acrylate monomer is preferably a group having a dicyclopentadiene skeleton, from the viewpoint of further reducing coloration of the optical molded body. Furthermore, from the viewpoint of reducing cure shrinkage during molding of the optical molded body, the alicyclic bifunctional (meth)acrylate monomer preferably contains tricyclodecane dimethanol di(meth)acrylate, more preferably tricyclodecane dimethanol di(meth)acrylate, and even more preferably tricyclodecane dimethanol dimethacrylate (e.g., DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0031] The linear bifunctional (meth)acrylate monomer is a (meth)acrylate having a linear structure in its molecular structure and two (meth)acryloyl groups. The linear structure preferably contains a divalent linear hydrocarbon group from the viewpoint of improving crack resistance during molding of the optical molded body. The number of carbon atoms in the divalent linear hydrocarbon group is, for example, 1 or more, preferably 2 or more, and more preferably 4 or more, from the viewpoint of reducing deviation in the liquid amount due to volatilization of the monomer during molding of the optical molded body. Furthermore, from the viewpoint of improving heat resistance, the number of carbon atoms in the divalent linear hydrocarbon group is preferably 20 or less, more preferably 14 or less.

[0032] Specific examples of the linear bifunctional (meth)acrylate monomer include di(meth)acrylates of alkanediols. The linear bifunctional (meth)acrylate monomer is preferably 1,6-hexanediol di(meth)acrylate (e.g., A-HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,9-nonanediol di(meth)acrylate (e.g., A-NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; Light Acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.; NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; Light Acrylate 1,9-ND-M, manufactured by Kyoeisha Chemical Co., Ltd.), 1,10-decanediol di(meth)acrylate (e.g., A-DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,12-dodecanediol di(meth)acrylate (e.g., A-DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.), or 1,12-dodecanediol di(meth)acrylate (e.g., A-DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.). The di(meth)acrylate may comprise one or more selected from the group consisting of (meth)acrylates (e.g., DDD, manufactured by Shin-Nakamura Chemical Co., Ltd.; SR262, manufactured by Arkema), ethylene glycol di(meth)acrylates (e.g., SR206NS, manufactured by Arkema), triethylene glycol di(meth)acrylates (e.g., SR272, manufactured by Arkema), polyethylene glycol di(meth)acrylates (e.g., A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,3-butanediol di(meth)acrylates (e.g., BG, manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1,4-butanediol di(meth)acrylates (e.g., BD, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0033] From the viewpoint of reducing cracks that occur in the optical molded body, the linear bifunctional (meth)acrylate monomer more preferably contains one or more (meth)acrylates selected from the group consisting of 1,12-dodecanediol di(meth)acrylate and 1,9-nonanediol di(meth)acrylate.

[0034] The bifunctional or higher functional (meth)acrylate monomer (A2) preferably has an alicyclic skeleton, from the viewpoint of further reducing coloration of the optical molded body. The bifunctional or higher functional (meth)acrylate monomer (A2) more preferably includes tricyclodecane dimethanol di(meth)acrylate, and more preferably includes tricyclodecane dimethanol dimethacrylate, from the viewpoint of further reducing coloration of the optical molded body.

[0035] The di- or higher functional (meth)acrylate monomer (A2) preferably has a straight-chain hydrocarbon skeleton, from the viewpoint of further reducing coloration of the optical molded body. The di- or higher functional (meth)acrylate monomer (A2) more preferably includes 1,12-dodecanediol di(meth)acrylate, and even more preferably includes 1,12-dodecanediol dimethacrylate, from the viewpoint of further reducing coloration of the optical molded body.

[0036] The difunctional or higher (meth)acrylate monomer (A2) may include a difunctional or higher (meth)acrylate monomer (A2) other than a linear difunctional (meth)acrylate monomer and an alicyclic difunctional (meth)acrylate monomer. The difunctional or higher (meth)acrylate monomer (A2) may include, for example, a trifunctional or higher (meth)acrylate monomer. The difunctional or higher (meth)acrylate monomer (A2) may include, for example, one or more selected from the group consisting of a difunctional or higher (meth)acrylate monomer (A2) having an aromatic ring and a difunctional or higher (meth)acrylate monomer (A2) having a branched chain. The difunctional or higher (meth)acrylate monomer (A2) may include, for example, one or more selected from the group consisting of an aromatic ring bifunctional (meth)acrylate monomer and a branched chain bifunctional (meth)acrylate monomer. The aromatic ring bifunctional (meth)acrylate monomer is a (meth)acrylate having an aromatic ring and two (meth)acryloyl groups in its molecular structure. The branched chain bifunctional (meth)acrylate monomer is a (meth)acrylate having a branched chain structure and two (meth)acryloyl groups in its molecular structure.

[0037] In the photocurable resin composition of this embodiment, the total content of the difunctional or higher (meth)acrylate monomers (A2) excluding the difunctional or higher (meth)acrylate monomer (A2) having an aromatic ring is, from the viewpoint of being able to further reduce the in-plane retardation of the optical molded body, preferably 60 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 100 parts by mass or less, even more preferably 80 parts by mass or more and 100 parts by mass or less, even more preferably 85 parts by mass or more and 100 parts by mass or less, even more preferably 90 parts by mass or more and 100 parts by mass or less, and even more preferably 95 parts by mass or more and 100 parts by mass or less, when the total content of the difunctional or higher (meth)acrylate monomers (A2) is taken as 100 parts by mass.

[0038] In the photocurable resin composition of the present embodiment, the total content of the difunctional or higher functional (meth)acrylate monomers (A2) excluding the difunctional or higher functional (meth)acrylate monomer (A2) having a branched chain is, from the viewpoint of further reducing the in-plane retardation of the optical molded body, preferably 60 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 100 parts by mass or less, even more preferably 80 parts by mass or more and 100 parts by mass or less, even more preferably 85 parts by mass or more and 100 parts by mass or less, even more preferably 90 parts by mass or more and 100 parts by mass or less, and even more preferably 95 parts by mass or more and 100 parts by mass or less, when the total content of the difunctional or higher functional (meth)acrylate monomers (A2) is taken as 100 parts by mass.

[0039] <Antioxidant (B)> The photocurable resin composition of this embodiment may further include an antioxidant (B). The antioxidant (B) is not particularly limited, and known antioxidants can be used. The antioxidant (B) includes, for example, one or more selected from the group consisting of phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, hindered amine-based antioxidants, and thioether-based antioxidants.

[0040] Examples of phenolic antioxidants include 2,6-di-t-butylhydroxytoluene and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of commercially available phenolic antioxidants include AO-20, AO-30, AO-40, AO-50, AO-60, and AO-80 from the Adeka STAB series manufactured by ADEKA Corporation.

[0041] Examples of phosphorus-based antioxidants include phosphines such as trialkylphosphine and triarylphosphine, trialkyl phosphites, triaryl phosphites, etc. Commercially available phosphorus-based antioxidants include PEP-4C, PEP-8, PEP-24G, PEP-36, HP-10, 260, 522A, 329K, 1178, 1500, 135A, and 3010 from the Adeka STAB series manufactured by ADEKA Corporation.

[0042] Examples of sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, laurylstearyl 3,3-thiodipropionate, pentaerythritol-tetrakis-(β-lauryl-thio-propionate), 3,9-bis(2-dodecylthioethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, and the like.

[0043] Examples of hindered amine antioxidants include bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine, decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester, and bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate. Examples of commercially available hindered amine antioxidants include AL-72 from the Adekastab series manufactured by ADEKA Corporation, and 111FDL, 123, 144, 152, 292, and 5100 from the TINUVIN series manufactured by BASF.

[0044] Examples of thioether antioxidants include ditridecyl 3,3'-thiobispropionate and 2,2-bis[[3-(dodecylthio)-1-oxopropyloxy]methyl]-1,3-propanediyl bis[3-(dodecylthio)propionic acid]. Examples of commercially available thioether antioxidants include AO-26, AO-412S, and AO-503A from the Adeka STAB series manufactured by ADEKA Corporation.

[0045] From the viewpoint of reducing discoloration of the optical molded body, the antioxidant (B) preferably includes one or more antioxidants selected from the group consisting of phenolic antioxidants and thioether antioxidants. From the viewpoint of further reducing discoloration of the optical molded body, the antioxidant (B) more preferably includes one or more antioxidants selected from the group consisting of 2,2-bis[[3-(dodecylthio)propionic acid]3-oxopropyloxy]methyl]-1,3-propanediyl (e.g., Adekastab AO-412S, manufactured by ADEKA Corporation) and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (e.g., Adekastab AO-60, manufactured by ADEKA Corporation).

[0046] From the viewpoint of reducing coloration of the optical molded body, the content of the antioxidant (B) in the photocurable resin composition of this embodiment is preferably 0.010 parts by mass or more and 10 parts by mass or less, more preferably 0.050 parts by mass or more and 5.0 parts by mass or less, even more preferably 0.10 parts by mass or more and 3.0 parts by mass or less, even more preferably 0.20 parts by mass or more and 2.0 parts by mass or less, and even more preferably 0.50 parts by mass or more and 1.5 parts by mass or less, when the total content of the monofunctional (meth)acrylate monomer (A1) and the di- or higher functional (meth)acrylate monomer (A2) is taken as 100 parts by mass.

[0047] From the viewpoint of reducing coloration of the optical molded body, the content of the antioxidant (B) in the photocurable resin composition of this embodiment is preferably 0.010% by mass or more and 5.0% by mass or less, more preferably 0.050% by mass or more and 4.0% by mass or less, even more preferably 0.10% by mass or more and 3.0% by mass or less, even more preferably 0.50% by mass or more and 2.0% by mass or less, and even more preferably 0.90% by mass or more and 1.0% by mass or less, when the total amount of solids in the photocurable resin composition (the total amount of components that remain as solids when cured) is taken as 100% by mass.

[0048] <Photopolymerization initiator (C)> The photocurable resin composition of the present embodiment may further contain a photopolymerization initiator (C). The photopolymerization initiator (C) is not particularly limited, and a known polymerization initiator can be used.

[0049] From the viewpoint of stably forming an optical molded body at low temperatures, the photopolymerization initiator (C) preferably contains a photoradical polymerization initiator. The photoradical polymerization initiator is a compound that generates radicals upon irradiation with ultraviolet light or visible light. Examples of the photoradical polymerization initiator include acylphosphine oxide-based initiators, oxyphenylacetic acid ester-based initiators, benzoylformic acid-based initiators, and hydroxyphenyl ketone-based initiators.

[0050] Examples of the photopolymerization initiator (C) include benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, isopropyl benzoin ether, isobutyl benzoin ether, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 4- Ethyl dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 4,4'-di(t-butylperoxycarbonyl)benzophenone, 3,4,4'-tri(t-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(t-hexylperoxycarbonyl)benzophenone, 3,3'-di(methoxycarbonyl)-4,4'-di(t-butylperoxycarbonyl)benzophenone, 3,4'-di(methoxycarbonyl)-4,3' -di(t-butylperoxycarbonyl)benzophenone, 4,4'-di(methoxycarbonyl)-3,3'-di(t-butylperoxycarbonyl)benzophenone, 2-(4'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine , 2-(4'-pentyloxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 4-[p-N,N-di(ethoxycarbonylmethyl)]-2,6-di(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2'-chlorophenyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(4'-methoxyphenyl)-s-triazine, 2-(p-dimethylaminostyryl)benzoxazole, 2-(p-dimethylaminostyryl)benzthiazole, 2-mercaptobenzothiazole, 3,3'-Carbonylbis(7-diethylaminocoumarin), 2-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dibromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 3-(2-methyl-2-dimethylaminopropionyl)carbazole, 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-dodecylcarbazole, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-fluoropropanol phenyl-1-propanone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-1-propanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4 -(4-morpholinyl)phenyl]-1-butanone, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, methyl benzoylformate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphinic acid ester, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime)], 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethanone-1-(O-acetyloxime), etc.

[0051] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the photopolymerization initiator (C) preferably contains a hydroxyphenyl ketone initiator, and more preferably contains 1-hydroxycyclohexyl phenyl ketone (for example, Omnirad 184, manufactured by IGM Resins).

[0052] In order to improve the curability of the photocurable resin composition, the content of the photopolymerization initiator (C) in the photocurable resin composition of this embodiment is preferably 0.10 parts by mass or more, more preferably 0.50 parts by mass or more, even more preferably 1.0 parts by mass or more, even more preferably 2.0 parts by mass or more, and even more preferably 3.0 parts by mass or more, based on 100 parts by mass of the total content of the monofunctional (meth)acrylate monomer (A1) and the difunctional or higher (meth)acrylate monomer (A2). In order to improve the thickness uniformity of the photocurable resin composition upon curing, the content of the photopolymerization initiator (C) in the photocurable resin composition of this embodiment is preferably 10 parts by mass or less, more preferably 8.0 parts by mass or less, even more preferably 6.0 parts by mass or less, even more preferably 5.0 parts by mass or less, and even more preferably 4.5 parts by mass or less, based on 100 parts by mass of the total content of the monofunctional (meth)acrylate monomer (A1) and the difunctional or higher (meth)acrylate monomer (A2). From the viewpoint of improving the curability of the photocurable resin composition and the viewpoint of improving the thickness uniformity of the photocurable resin composition when cured, the content of the photopolymerization initiator (C) in the photocurable resin composition of this embodiment is preferably 0.10 parts by mass or more and 10 parts by mass or less, more preferably 0.50 parts by mass or more and 8.0 parts by mass or less, even more preferably 1.0 parts by mass or more and 6.0 parts by mass or less, even more preferably 2.0 parts by mass or more and 5.0 parts by mass or less, and still more preferably 3.0 parts by mass or more and 4.5 parts by mass or less, when the total content of the monofunctional (meth)acrylate monomer (A1) and the di- or higher functional (meth)acrylate monomer (A2) is taken as 100 parts by mass.

[0053] From the viewpoint of further reducing the in-plane retardation of the optical molded body, the content of the photopolymerization initiator (C) in the photocurable resin composition of this embodiment is preferably 0.10% by mass or more and 10% by mass or less, more preferably 1.0% by mass or more and 8.0% by mass or less, even more preferably 2.0% by mass or more and 6.0% by mass or less, even more preferably 3.0% by mass or more and 5.0% by mass or less, and even more preferably 3.5% by mass or more and 4.0% by mass or less, when the total amount of solids in the photocurable resin composition (the total amount of components that remain as solids when cured) is taken as 100% by mass.

[0054] <Light Stabilizer (D)> The photocurable resin composition of the present embodiment may further contain a light stabilizer (D). The light stabilizer (D) is not particularly limited, and a known light stabilizer can be used. By containing the light stabilizer (D), the coloration resistance of the photocurable resin composition can be improved.

[0055] The light stabilizer (D) preferably contains a hindered amine-based light stabilizer from the viewpoint of further improving coloration resistance.

[0056] Examples of hindered amine light stabilizers include methacrylic acid (1,2,2,6,6-pentamethyl-piperidin-4-yl), decanedioic acid bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl) ester, a mixture of 70% by mass of a reaction product of 1,1-dimethylethyl hydroperoxide and octane and 30% by mass of polypropylene, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, and a mixture of methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate. a mixture of 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, a mixture of 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4-butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate, and a mixture of 1,2,2,6,6-pentamethyl-4-piperidyl-1,2,3,4-butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate.

[0057] From the viewpoint of further improving coloration resistance, the light stabilizer (D) preferably contains 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (for example, Adekastab LA-82, manufactured by ADEKA Corporation).

[0058] The content of the light stabilizer (D) in the photocurable resin composition of this embodiment is preferably 0.0010% by mass or more, more preferably 0.0050% by mass or more, even more preferably 0.010% by mass or more, even more preferably 0.050% by mass or more, and even more preferably 0.090% by mass or more, when the total amount of solids in the photocurable resin composition (the total amount of components remaining as solids when cured) is taken as 100% by mass, from the viewpoint of improving the coloration resistance of the optical molded body. The content of the light stabilizer (D) in the photocurable resin composition of this embodiment is preferably 1.00% by mass or less, more preferably 0.60% by mass or less, even more preferably 0.50% by mass or less, even more preferably 0.40% by mass or less, and even more preferably 0.30% by mass or less, when the total amount of solids in the photocurable resin composition (the total amount of components remaining as solids when cured) is taken as 100% by mass, from the viewpoint of reducing bleed-out. From the viewpoint of improving the coloring resistance of the optical molded body and reducing bleed-out, the content of the light stabilizer (D) in the photocurable resin composition of this embodiment is preferably 0.0010% by mass or more and 1.00% by mass or less, more preferably 0.0050% by mass or more and 0.60% by mass or less, even more preferably 0.010% by mass or more and 0.50% by mass or less, even more preferably 0.050% by mass or more and 0.40% by mass or less, and even more preferably 0.090% by mass or more and 0.30% by mass or less, when the total amount of solids in the photocurable resin composition (the total amount of components that remain as solids when cured) is taken as 100% by mass.

[0059] <Other Components> The photocurable resin composition may include, as specific examples of other components other than the polymerizable compound (e.g., the monofunctional (meth)acrylate monomer (A1) and the di- or higher functional (meth)acrylate monomer (A2)), the antioxidant (B), the photopolymerization initiator (C), and the light stabilizer (D), one or more selected from the group consisting of a filler, a curing accelerator, a plasticizer, a heat stabilizer, a flame retardant, an antistatic agent, an antifoaming agent, a silane coupling agent, an ultraviolet absorber, a surfactant, and a leveling agent.

[0060] <Method for producing photocurable resin composition> The photocurable resin composition according to the present invention can be obtained by mixing a polymerizable compound (e.g., a monofunctional (meth)acrylate monomer (A1), a di- or higher functional (meth)acrylate monomer (A2)) and, if necessary, other components such as an antioxidant (B), a photopolymerization initiator (C), or a light stabilizer (D) by a conventionally known method.

[0061] <Physical Properties of Photocurable Resin Composition> Next, the physical properties of the photocurable resin composition will be described.

[0062] The in-plane retardation Re of a cured film produced using the photocurable resin composition of this embodiment according to the following <Cured film production conditions> is measured according to the following <Measurement of in-plane retardation Re>. The following describes this.

[0063] The in-plane retardation Re of the photocurable resin composition of this embodiment is preferably 50.0 nm or less, more preferably 40.0 nm or less, even more preferably 35.0 nm or less, even more preferably 30.0 nm or less, even more preferably 25.0 nm or less, even more preferably 23.0 nm or less, more preferably 20.0 nm or less, even more preferably 15.0 nm or less, even more preferably 12.0 nm or less, even more preferably 10.0 nm or less, even more preferably 8.0 nm or less, even more preferably 6.0 nm or less, even more preferably 5.0 nm or less. The lower limit of the in-plane retardation Re of the photocurable resin composition of this embodiment is not particularly limited, for example, it may be 0.00 nm or more, 0.10 nm or more, 0.50 nm or more, 1.0 nm or more, 2.0 nm or more, or 3.0 nm or more. From the viewpoint of further reducing the in-plane retardation of the optical molded body, the in-plane retardation Re of the photocurable resin composition of this embodiment is preferably 0.00 nm or more and 50.0 nm or less, more preferably 0.00 nm or more and 40.0 nm or less, even more preferably 0.00 nm or more and 35.0 nm or less, even more preferably 0.00 nm or more and 30.0 nm or less, even more preferably 0.00 nm or more and 25.0 nm or less, even more preferably 0.00 nm or more and 23.0 nm or less, more preferably 0.00 nm or more and 20.0 nm or less, even more preferably 0.00 nm or more and 15.0 nm or less, even more preferably 0.00 nm or more and 12.0 nm or less, even more preferably 0.00 nm or more and 10.0 nm or less, even more preferably 0.00 nm or more and 8.0 nm or less, even more preferably 0.00 nm or more and 6.0 nm or less, and even more preferably 0.00 nm or more and 5.0 nm or less.

[0064] <Conditions for preparing a cured film> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet, and the circular hole was filled with the photocurable resin composition. A 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet was then placed on top of the sheet, and the height was adjusted using a SUS lab jack. The photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes from above the alkali-free glass sheet, and then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. After irradiating with the LED light, the sheet was allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was released from the alkali-free glass and silicone sheet to obtain a cured film of the photocurable resin composition. Here, as more specific conditions for producing a cured film of the photocurable resin composition of this embodiment, for example, the conditions described in the Examples can be adopted.

[0065] <Measurement of in-plane retardation Re> One hour after the completion of LED light irradiation, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film using a two-dimensional birefringence evaluation device in air at an ambient temperature of 23° C. Here, in this embodiment, the measurement of the in-plane retardation Re can be more specifically performed according to the method described in the examples.

[0066] Next, the in-plane retardation Re after heating is described, which is measured according to the <Measurement of in-plane retardation Re after heat treatment> below after subjecting a cured film prepared using the photocurable resin composition of this embodiment according to the above <Cured film preparation conditions> to the <Heat treatment> below.

[0067] The in-plane retardation Re of the photocurable resin composition of this embodiment after heating is preferably 16.0 nm or less, more preferably 13.0 nm or less, even more preferably 10.0 nm or less, even more preferably 8.0 nm or less, even more preferably 6.0 nm or less, even more preferably 5.0 nm or less, even more preferably 4.0 nm or less, even more preferably 3.5 nm or less, even more preferably 3.0 nm or less, even more preferably 2.5 nm or less. The lower limit of the in-plane retardation Re of the photocurable resin composition of this embodiment after heating is not particularly limited, but may be, for example, 0.00 nm or more, 0.10 nm or more, 0.50 nm or more, 1.0 nm or more, 2.0 nm or more, or 3.0 nm or more. From the viewpoint of further reducing the in-plane retardation of the optical molded body, the in-plane retardation Re of the photocurable resin composition of this embodiment after heating is preferably 0.00 nm or more and 16.0 nm or less, more preferably 0.00 nm or more and 13.0 nm or less, even more preferably 0.00 nm or more and 10.0 nm or less, even more preferably 0.00 nm or more and 8.0 nm or less, even more preferably 0.00 nm or more and 6.0 nm or less, even more preferably 0.00 nm or more and 5.0 nm or less, even more preferably 0.00 nm or more and 4.0 nm or less, even more preferably 0.00 nm or more and 3.5 nm or less, even more preferably 0.00 nm or more and 3.0 nm or less, and even more preferably 0.00 nm or more and 2.5 nm or less.

[0068] <Heat Treatment> The cured film is heated from 23°C to 120°C at a uniform rate over 1 hour, heated at 120°C for 1 hour, then cooled from 120°C to 23°C at a uniform rate over 3 hours, and then cooled at 23°C for 3 hours.

[0069] <Measurement of In-Plane Retardation After Heat Treatment> One hour after the completion of the <heat treatment>, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film using a two-dimensional birefringence evaluation device in air at an ambient temperature of 23°C.

[0070] <Uses of Photocurable Resin Composition> Next, uses of the photocurable resin composition will be described.

[0071] The photocurable resin composition of this embodiment can reduce the in-plane retardation of an optical molded body molded from the photocurable resin composition, and therefore can be used in methods for forming optical molded bodies, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, and casting. In particular, the photocurable resin composition of this embodiment can be used in casting.

[0072] The photocurable resin composition of this embodiment can reduce the in-plane retardation of an optical molded body molded from the photocurable resin composition, and therefore the use of the optical molded body molded from the photocurable resin composition is not particularly limited, and the optical molded body can be used for a variety of purposes.

[0073] The photocurable resin composition of this embodiment can be preferably used, for example, for lenses, including, for example, one or more lenses selected from the group consisting of spherical lenses, aspherical lenses, biconvex lenses, plano-convex lenses, convex meniscus lenses, biconcave lenses, plano-concave lenses, and concave meniscus lenses.

[0074] The photocurable resin composition of this embodiment can be used, for example, more preferably, for one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

[0075] The photocurable resin composition of the present embodiment can be preferably used, for example, for a display cover (hereinafter also referred to as a cover display). The cover display includes, for example, one or more types selected from the group consisting of a front cover display and a full cover display.

[0076] The photocurable resin composition of this embodiment can be used, for example, more preferably, for one or more cover displays selected from the group consisting of cover displays for virtual reality devices (cover displays for VR devices), cover displays for mixed reality devices (cover displays for MR devices), cover displays for augmented reality devices (cover displays for AR devices), cover displays for cross reality devices (cover displays for xR devices), and cover displays for head-mounted displays (cover displays for HMDs).

[0077] (Cured Product) The cured product of this embodiment is a cured product of the photocurable resin composition of this embodiment. The cured product of this embodiment can be produced, for example, by irradiating the photocurable resin composition of this embodiment with LED light to cure it. Note that, as more specific production conditions for the cured product of this embodiment, for example, the conditions described in the Examples can be adopted.

[0078] (Optical Molded Body) The optical molded body of this embodiment includes a cured product of the photocurable resin composition of this embodiment. The optical molded body of this embodiment can be produced using the photocurable resin composition of this embodiment. The optical molded body can be produced from the photocurable resin composition of this embodiment by any method, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, and casting.

[0079] The optical molded body of the present embodiment includes a lens, for example, one or more lenses selected from the group consisting of a spherical lens, an aspherical lens, a biconvex lens, a plano-convex lens, a convex meniscus lens, a biconcave lens, a plano-concave lens, and a concave meniscus lens.

[0080] The lens of this embodiment includes one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

[0081] The optical molded body of this embodiment includes a display cover (cover display). The cover display includes, for example, one or more types selected from the group consisting of a front cover display and a full cover display.

[0082] The cover display of this embodiment includes one or more types selected from the group consisting of a cover display for a virtual reality device (a cover display for a VR device), a cover display for a mixed reality device (a cover display for an MR device), a cover display for an augmented reality device (a cover display for an AR device), a cover display for a cross reality device (a cover display for an xR device), and a cover display for a head-mounted display (a cover display for an HMD).

[0083] The maximum thickness portion of the optical molded body is the portion of the optical molded body where the thickness of the optical member is greatest. The position of the maximum thickness portion of the optical molded body is not particularly limited and can be set appropriately depending on the application, etc.

[0084] For example, the optical molded body of this embodiment preferably has a maximum thickness of 1.0 mm or more, more preferably a maximum thickness of 1.1 mm or more, even more preferably a maximum thickness of 1.2 mm or more, even more preferably a maximum thickness of 1.5 mm or more, even more preferably a maximum thickness of 2.0 mm or more, even more preferably a maximum thickness of 3.0 mm or more, even more preferably a maximum thickness of 4.0 mm or more, and even more preferably a maximum thickness of 5.0 mm or more.

[0085] For example, the optical molded body of this embodiment preferably has a maximum thickness of 20.0 mm or less, more preferably a maximum thickness of 19.9 mm or less, even more preferably a maximum thickness of 19.8 mm or less, even more preferably a maximum thickness of 19.5 mm or less, even more preferably a maximum thickness of 18.0 mm or less, even more preferably a maximum thickness of 17.0 mm or less, even more preferably a maximum thickness of 16.0 mm or less, and even more preferably a maximum thickness of 15.0 mm or less.

[0086] For example, the optical molded body of this embodiment preferably has a maximum thickness of 1.0 mm or more and 20.0 mm or less, more preferably a maximum thickness of 1.1 mm or more and 19.9 mm or less, even more preferably a maximum thickness of 1.2 mm or more and 19.8 mm or less, even more preferably a maximum thickness of 1.5 mm or more and 19.5 mm or less, even more preferably a maximum thickness of 2.0 mm or more and 19.0 mm or less, even more preferably a maximum thickness of 3.0 mm or more and 18.0 mm or less, even more preferably a maximum thickness of 4.0 mm or more and 17.0 mm or less, even more preferably a maximum thickness of 5.0 mm or more and 16.0 mm or less, and even more preferably a maximum thickness of 5.0 mm or more and 15.0 mm or less.

[0087] The photocurable resin composition of this embodiment can reduce the in-plane retardation of an optical molded body, and therefore can be applied to optical molded bodies having a thickness of 1.0 mm or more.

[0088] (Optical Device) The optical device of this embodiment includes the optical molded body of this embodiment. The type of the optical device of this embodiment is not particularly limited. Examples of the optical device of this embodiment include a virtual reality device (VR device), a mixed reality device (MR device), an augmented reality device (AR device), a cross reality device (xR device), and a head-mounted display (HMD device).

[0089] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements that do not impair the effects of the present invention are included in the present invention.

[0090] The present embodiment will be described in detail below with reference to examples, etc. However, the present embodiment is not limited to the descriptions of these examples.

[0091] First, the materials used in each example are listed below. Polymerizable compound: (meth)acrylate monomer (A) Monofunctional (meth)acrylate monomer (A1) 1: GM81HDA (dicyclopentanyl methacrylate, manufactured by Kokusei Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2) 1: DDD (1,12-dodecanediol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2) 2: DCP (tricyclodecane dimethanol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2) 3: GM82R2E (2,2-bis[4-[2-(methacryloyloxy)ethoxy]phenyl]propane, manufactured by Kokusei Chemical Co., Ltd.)

[0092] Antioxidants (B) Antioxidant 1: thioether-based antioxidant (2,2-bis[[3-(dodecylthio)propionic acid]3-(dodecylthio)-1-oxopropyloxy]methyl]-1,3-propanediyl, manufactured by ADEKA Corporation, product name: Adekastab AO-412S) (hereinafter also referred to as AO-412S) Antioxidant 2: phenol-based antioxidant (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA Corporation, product name: Adekastab AO-60) (hereinafter also referred to as AO-60) Photopolymerization initiator (C) Photopolymerization initiator 1: photoradical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, manufactured by IGM Resins, product name: Omnirad 184) Light Stabilizer (D) Light Stabilizer 1: Hindered amine light stabilizer (1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, manufactured by ADEKA Corporation, product name: Adekastab LA-82) (hereinafter also referred to as LA-82)

[0093] (Examples 1 to 3, Comparative Example 1) Liquid photocurable resin compositions were obtained by blending the components to obtain the formulations shown in Table 1. The formulations in Table 1 are expressed in parts by mass. The physical properties of optical molded articles obtained from the photocurable resin compositions of each example were measured by the following methods. The measurement results are shown in Table 1.

[0094] <Measurement of In-Plane Retardation Re> The in-plane retardation Re of the cured film prepared using the photocurable resin composition of each example according to the following <Cured Film Preparation Conditions> was measured according to the following <Measurement of In-Plane Retardation Re>. <Cured Film Preparation Conditions> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass (product name: JIS R 3202, glass plate thread surface, manufactured by Test Piece Co., Ltd.). The circular hole in the silicone sheet was filled with the photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass (product name: JIS R 3202, glass plate thread surface, manufactured by Test Piece Co., Ltd.) was further placed on top. At this time, it was confirmed that no air bubbles were present. Hereinafter, the product obtained by placing a silicone sheet on the alkali-free glass described above, filling the circular holes in the silicone sheet with photocurable resin, and then placing alkali-free glass on top of that may be referred to as a stack. The resulting laminate was placed on a SUS lab jack to adjust the height, and using an LED light irradiation device (manufactured by CCS, product name: 405 nm-120 mm air-cooled batch-type irradiation device, model number: HLDL-120505-NWPSC), the photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes from above the alkali-free glass. The laminate was then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. After irradiation with LED light, the product was allowed to cool at 23°C for 30 minutes. After cooling, the cured product of the photocurable resin composition was released from the alkali-free glass and silicone sheet to obtain a cured film of the photocurable resin composition. The irradiation intensity of the LED light was measured using an ultraviolet integrating actinometer (product name: UIT-250, manufactured by Ushio Inc.).

[0095] <Measurement of In-Plane Retardation> For the cured film of each example, one hour after the completion of the LED light irradiation, the in-plane retardation Re was measured at 10.0 mm from the center of the cured film in the atmosphere at an ambient temperature of 23°C using a two-dimensional birefringence evaluation device in accordance with the following <Measurement conditions for in-plane retardation Re> and <Measurement steps>.

[0096] <Conditions for measuring in-plane retardation Re> Apparatus: 2D birefringence evaluation device (product name: WPA-200, manufactured by Photonic Lattice) Analysis software: WPA-view Measurement temperature: 23°C Pressure: atmospheric pressure Selection area: Within a 17.5 mm radius from the center of the cured film Analysis area: Within a 10.0 mm radius from the center of the cured film Measurement field of view: 30 mm x 40 mm Number of birefringence pixels: 384 x 288 pixels Lens: Standard lens (f1.25) User settings Automatic exposure adjustment: Automatic exposure adjustment is performed during measurement Noise filter: Automatically applied Masking of dark areas: Performs masking (10.0%) Axis direction setting: Slow axis Measurement accuracy: High precision Measurement mode: 3-wavelength measurement Measurement wavelengths: 523 nm, 543 nm, 575 nm Material coefficient: Automatic

[0097] <Measurement Steps> (S1) The device was powered on, the software (WPA-view) was launched, and then at least 30 minutes was allowed to stabilize. (S2) After placing the cured film on the light source stage, the height of the camera unit was adjusted so that the cured film was within the area where the light source stage was displayed in the camera preview window. At this time, the cured film was prevented from floating above the light source stage. It was also visually confirmed that external light was not reflected in the preview window. (S3) The lens dial was turned to focus on the cured film. For the measurement of the cured film, the dial was set to "4." (S4) The above conditions were set in the user settings. Next, the cured film was removed and the baseline was measured. The baseline measurement was performed for each cured film. (S5) The cured film was repositioned and the measurement was performed. (S6) On the analysis screen, the selected area was adjusted so that it was within the measurement field of view, and the in-plane retardation Re, etc. were measured.

[0098] <Measurement of in-plane retardation Re after heating> Cured films prepared using the photocurable resin composition according to the above <Cured film preparation conditions> were subjected to the following <Heat treatment>. The in-plane retardation Re of each cured film after the <Heat treatment> was measured according to the <Measurement of in-plane retardation Re after heat treatment> below. Heating of each cured film was started at least 1 hour and within 3 hours after preparation of the cured film.

[0099] <Heat Treatment> The cured film is heated from 23°C to 120°C at a uniform rate over 1 hour, heated at 120°C for 1 hour, then cooled from 120°C to 23°C at a uniform rate over 3 hours, and then cooled at 23°C for 3 hours.

[0100] <Measurement of in-plane retardation Re after heat treatment> One hour after the completion of the above <heat treatment>, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film in air at an ambient temperature of 23°C using a two-dimensional birefringence evaluation device.

[0101]

[0102] This application claims priority based on Japanese Patent Application No. 2024-012864, filed January 31, 2024, the disclosure of which is incorporated herein in its entirety by reference.

Claims

1. A photocurable resin composition that can be used for optical molded bodies, comprising a difunctional or higher functional (meth)acrylate monomer, including one or more selected from the group consisting of alicyclic difunctional (meth)acrylate monomers and linear difunctional (meth)acrylate monomers, wherein the total content of the difunctional or higher functional (meth)acrylate monomers is 100 parts by mass, and the total content of the alicyclic difunctional (meth)acrylate monomer and the linear difunctional (meth)acrylate monomer is 60 parts by mass or more and 100 parts by mass or less.

2. The photocurable resin composition according to claim 1, comprising one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and the difunctional or higher functional (meth)acrylate monomers, wherein the content of the difunctional or higher functional (meth)acrylate monomer is 5.0 parts by mass or more and 90 parts by mass or less when the total content of the monofunctional (meth)acrylate monomer and the difunctional or higher functional (meth)acrylate monomer is 100 parts by mass.

3. The photocurable resin composition according to claim 2, which contains the monofunctional (meth)acrylate monomer.

4. The photocurable resin composition according to claim 2 or 3, wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton.

5. The photocurable resin composition according to any one of claims 1 to 4, wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> below has an in-plane retardation Re of 50.0 nm or less, as measured according to the <Measurement of In-Plane Retardation Re> below. <Conditions for Producing Cured Film> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet. The circular hole was filled with the photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet was placed on top of the silicone-free glass sheet. The height was adjusted by placing this on a stainless steel lab jack. The photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW from above the alkali-free glass sheet for 3 minutes, then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass sheet was then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was released from the alkali-free glass sheet and the silicone sheet to obtain a cured film of the photocurable resin composition. <Measurement of In-Plane Retardation> One hour after the completion of the LED light irradiation, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film in air at an ambient temperature of 23°C using a two-dimensional birefringence evaluation device.

6. The photocurable resin composition according to any one of claims 1 to 5, wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> below is subjected to the <Heat Treatment> below, and the in-plane retardation Re after heating is measured according to the <Measurement of In-Plane Retardation After Heat Treatment> below, and is 16.0 nm or less. <Conditions for Producing Cured Film> A 3 mm thick, 50 mm x 50 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 35 mm diameter circular hole was placed on a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet. The circular hole was filled with the photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass sheet was placed on top of the silicone-free glass sheet. The height was adjusted by placing this on a stainless steel lab jack. The photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW from above the alkali-free glass sheet for 3 minutes, then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass sheet was then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was released from the alkali-free glass sheet and the silicone sheet to obtain a cured film of the photocurable resin composition. <Heat Treatment> The cured film is heated from 23° C. to 120° C. at a uniform rate over 1 hour, heated at 120° C. for 1 hour, then cooled from 120° C. to 23° C. at a uniform rate over 3 hours, and then cooled for a further 3 hours at 23° C. <Measurement of In-Plane Retardation after Heat Treatment> One hour after the completion of the <Heat Treatment>, the in-plane retardation Re of the cured film is measured at 10.0 mm from the center of the cured film using a two-dimensional birefringence evaluation device in air at an ambient temperature of 23° C.

7. The photocurable resin composition according to any one of claims 1 to 6, further comprising an antioxidant.

8. The photocurable resin composition according to any one of claims 1 to 7, further comprising a photopolymerization initiator.

9. The photocurable resin composition according to claim 8, wherein the photopolymerization initiator comprises a photoradical polymerization initiator.

10. The photocurable resin composition according to any one of claims 1 to 9, further comprising a light stabilizer.

11. The photocurable resin composition according to any one of claims 1 to 10, which can be used in a casting method.

12. The photocurable resin composition according to any one of claims 1 to 11, which can be used for one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

13. A cured product of the photocurable resin composition according to any one of claims 1 to 12.

14. An optical molded body comprising a cured product of the photocurable resin composition according to any one of claims 1 to 12.

15. The optical molded body of claim 14, wherein the optical molded body comprises a lens.

16. The optical molded body according to claim 15, wherein the lens comprises one or more lenses selected from the group consisting of lenses for virtual reality devices (VR lenses), lenses for mixed reality devices (MR lenses), lenses for augmented reality devices (AR lenses), lenses for cross reality devices (xR lenses), and lenses for head-mounted displays (HMD lenses).

17. The optical molded body according to any one of claims 14 to 16, wherein the maximum thickness is 20.0 mm or less.

18. The optical molded body according to any one of claims 14 to 17, wherein the maximum thickness is 1.0 mm or more.

19. An optical device comprising the optical molded body according to any one of claims 14 to 18.

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