Photocurable resin composition, optical molded product, and optical device

Abstract

Provided is a photocurable resin composition which can be used for an optical molded product, wherein the humidity swelling rate α 1 measured according to a prescribed method in a cured film manufactured according to prescribed conditions using the photocurable resin composition is 1.00% or less.

Description

Photocurable resin composition, optical molded body, and optical device

[0001] The present invention relates to a photocurable resin composition, 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 that can reduce the occurrence of cracks in optical molded articles.

[0007] The present inventors conducted extensive research to achieve the above-mentioned object. As a result, they found that the humidity swelling ratio of a photocurable resin composition measured under specific conditions is correlated with the occurrence of cracks in the resulting optical molded body. Based on the above findings, the present inventors conducted further extensive research and found that the occurrence of cracks in the optical molded body can be reduced by using a photocurable resin composition having a humidity swelling ratio of 1.00% or less measured under specific conditions, thereby completing the present invention.

[0008] [1] A photocurable resin composition usable for an optical molded body, wherein a cured film produced using the photocurable resin composition according to the following <Cured Film Production Conditions> has a humidity swelling ratio α1 of 1.00% or less as measured by the following <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)>. <Cured Film Production Conditions> A 100 μm-thick, 100 mm x 100 mm PET film and a 500 μm-thick, 100 mm x 100 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 50 mmφ circular hole are placed in this order on a 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet, the circular hole is filled with the photocurable resin composition, and then the 100 μm-thick, 100 mm x 100 mm PET film and the 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet are placed on top of the 100 μm-thick, 100 mm x 100 mm PET film and the 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet. The above-mentioned items are further placed in this order, and this is placed on an SUS lab jack to adjust the height. One of the alkali-free glasses is irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes onto the photocurable resin composition, and then the glass is turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass is then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition is released from the alkali-free glass, the PET film, and the silicone sheet to obtain a cured film. <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> The cured film was cut into a strip having a width of 5 mm and a length of 15 mm to prepare a test piece. The test piece was subjected to humidity-conditioned thermomechanical analysis (humidity-conditioned TMA) in a tensile mode with a load of 5 gf, a chuck distance of 10 mm, in a nitrogen atmosphere, and at a constant temperature of 65°C. The test piece was subjected to the following consecutive steps: maintaining the test piece at a humidity of 0% RH for 30 minutes; increasing the humidity from 0% RH to 90% RH at a humidity increase rate of 5% RH / min (humidity increase step); maintaining the test piece at a humidity of 90% RH for 150 minutes; decreasing the humidity from 90% RH to 0% RH at a humidity decrease rate of 5% RH / min (humidity decrease step); and maintaining the test piece at a humidity of 0% RH for 30 minutes. The humidity swelling ratio in the humidity increase step was designated as the humidity swelling ratio α1. [2] The photocurable resin composition according to [1], wherein the humidity swelling rate α1 is −0.40% or more.[3] The photocurable resin composition according to [1] or [2], wherein the humidity swelling rate in the humidity decreasing step is a humidity swelling rate α2, and a cured film produced using the photocurable resin composition according to the <Cured Film Production Conditions> has a humidity swelling rate α2 of 0.00% or less as measured by <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)>. [4] The photocurable resin composition according to any of [1] to [3], which contains a (meth)acrylate monomer. [5] The photocurable resin composition according to [4], wherein the (meth)acrylate monomer contains a methacrylate monomer. [6] The photocurable resin composition according to [4] or [5], wherein the (meth)acrylate monomer contains one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and di- or higher-functional (meth)acrylate monomers. [7] The photocurable resin composition according to [6], wherein the content of the monofunctional (meth)acrylate monomer is 0 to 100 parts by mass, relative to 100 parts by mass of the total content of the (meth)acrylate monomers. [8] The photocurable resin composition according to any one of [4] to [7], wherein the (meth)acrylate monomer includes a (meth)acrylate monomer having an alicyclic skeleton. [9] The photocurable resin composition according to [8], wherein the (meth)acrylate monomer having an alicyclic skeleton has one or more skeletons selected from the group consisting of an adamantane skeleton, a norbornane skeleton, and a dicyclopentadiene skeleton.

[10] The photocurable resin composition according to [8] or [9], wherein the content of the (meth)acrylate monomer having an alicyclic skeleton is 30 to 100 parts by mass, relative to 100 parts by mass of the total content of the (meth)acrylate monomers.

[11] The photocurable resin composition according to any one of [4] to

[10] above, wherein the (meth)acrylate monomer comprises a (meth)acrylate monomer having a linear hydrocarbon skeleton.

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

[11] above, further comprising a light stabilizer.

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

[12] above, further comprising an antioxidant.

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

[13] above, further comprising a photopolymerization initiator.

[15] The photocurable resin composition according to

[14] above, wherein the photopolymerization initiator comprises a photoradical polymerization initiator.

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

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

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

[16] 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).

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

[17] above.

[19] The optical molded body according to

[18] above, wherein the optical molded body comprises a lens.

[20] The optical molded body according to

[19] , 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).

[21] The optical molded body according to

[18] , wherein the optical molded body comprises a cover display.

[22] The optical molded body according to

[21] , wherein the cover display comprises one or more lenses selected from the group consisting of cover displays for virtual reality devices, cover displays for mixed reality devices, cover displays for augmented reality devices, cover displays for cross reality devices, and cover displays for head-mounted displays.

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

[18] to

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

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

[18] to

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

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

[18] to

[24] .

[0009] According to the present invention, it is possible to provide a photocurable resin composition that can reduce the occurrence of cracks in optical molded products.

[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 simply referred to as "resin composition" as appropriate) is a photocurable resin composition that can be used for an optical molded body.

[0012] The photocurable resin composition of this embodiment is a cured film produced using the photocurable resin composition according to the following <Cured Film Production Conditions>, and the humidity swelling ratio α1 measured by the following <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> is 1.00% or less. <Cured Film Production Conditions> A 100 μm-thick, 100 mm×100 mm PET film and a 500 μm-thick, 100 mm×100 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 50 mmφ circular hole were placed in this order on a 2.0 mm-thick, 100 mm×100 mm alkali-free glass sheet, the circular hole was filled with the photocurable resin composition, and then a 100 μm-thick, 100 mm×100 mm PET film and a 2.0 mm-thick, 100 mm×100 mm alkali-free glass sheet were placed on top of the ...500 μm-thick, 100 mm×100 mm silicone sheet with a 50 mmφ circular hole. Two pieces of alkali-free glass were further placed on top of each other in this order, and these were then placed on an SUS lab jack to adjust the height. One piece of alkali-free glass was irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes onto the photocurable resin composition, and the glass was then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass was then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition was then released from the alkali-free glass, PET film, and silicone sheet to obtain a cured film. <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> The cured film was cut into a strip having a width of 5 mm and a length of 15 mm to prepare a test piece. The test piece was subjected to humidity-conditioned thermomechanical analysis (humidity-conditioned TMA) in a tensile mode with a load of 5 gf, a chuck distance of 10 mm, in a nitrogen atmosphere, and at a constant temperature of 65°C. The test piece was subjected to the following consecutive steps: maintaining the test piece at a humidity of 0% RH for 30 minutes; increasing the humidity from 0% RH to 90% RH at a humidity increase rate of 5% RH / min (humidity increase step); maintaining the test piece at a humidity of 90% RH for 150 minutes; decreasing the humidity from 90% RH to 0% RH at a humidity decrease rate of 5% RH / min (humidity decrease step); and maintaining the test piece at a humidity of 0% RH for 30 minutes. The humidity swelling ratio in the humidity increase step was designated as the humidity swelling ratio α1. The photocurable resin composition of this embodiment has the above-described configuration, and therefore can reduce the occurrence of cracks in the optical molded article obtained from the photocurable resin composition of this embodiment.

[0013] The photocurable resin composition contains, for example, a polymerizable compound. The polymerizable compound preferably contains a (meth)acrylate monomer (A) from the viewpoint of further reducing the occurrence of cracks in the optical molded body.

[0014] 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.

[0015] 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.

[0016] <Polymerizable Compound> The polymerizable compound may be any compound having a polymerizable functional group, and is preferably a compound having a radically polymerizable functional group. From the viewpoint of reducing the occurrence of cracks in the optical molded body, for example, the radically polymerizable functional group may be a (meth)acryloyl group. From the viewpoint of reducing the occurrence of cracks in the optical molded body, the polymerizable compound preferably contains a (meth)acrylate monomer (A). From the viewpoint of reducing the coloration of the optical molded body, the (meth)acrylate monomer (A) preferably contains a methacrylate monomer.

[0017] <(Meth)acrylate Monomer (A)> The (meth)acrylate monomer (A) is a compound having a (meth)acryloyl group. The (meth)acrylate monomer (A) is a molecule that can bond to other molecules by radical polymerization of the (meth)acryloyl group.

[0018] From the viewpoint of improving the strength of an optical molded body obtained from the photocurable resin composition, the (meth)acrylate monomer (A) preferably contains one or more selected from the group consisting of monofunctional (meth)acrylate monomers (A1) and difunctional or higher functional (meth)acrylate monomers (A2).

[0019] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the content of the monofunctional (meth)acrylate monomer (A1) in the photocurable resin composition of this embodiment is preferably 0 parts by mass or more and 100 parts by mass or less, more preferably 1 part by mass or more and 100 parts by mass or less, even more preferably 10 parts by mass or more and 100 parts by mass or less, even more preferably 30 parts by mass or more and 100 parts by mass or less, even more preferably 50 parts by mass or more and 100 parts by mass or less, even more preferably 70 parts by mass or more and 100 parts by mass or less, and even more preferably 75 parts by mass or more and 100 parts by mass or less, when the total content of the (meth)acrylate monomer (A) is taken as 100 parts by mass.

[0020] From the viewpoint of further reducing the occurrence of cracks in 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 0 parts by mass or more and 100 parts by mass or less, more preferably 0 parts by mass or more and 90 parts by mass or less, even more preferably 0 parts by mass or more and 70 parts by mass or less, even more preferably 0 parts by mass or more and 50 parts by mass or less, even more preferably 0 parts by mass or more and 30 parts by mass or less, and even more preferably 0 parts by mass or more and 25 parts by mass or less, when the total content of the (meth)acrylate monomer (A) is taken as 100 parts by mass.

[0021] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the (meth)acrylate monomer (A) preferably contains a (meth)acrylate monomer having an alicyclic skeleton. From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the (meth)acrylate monomer having an alicyclic skeleton more preferably contains one or more skeletons selected from the group consisting of an adamantane skeleton, a norbornane skeleton, and a dicyclopentadiene skeleton. From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the (meth)acrylate monomer having an alicyclic skeleton further preferably contains one or more skeletons selected from the group consisting of dicyclopentanyl (meth)acrylate and isobornyl (meth)acrylate.

[0022] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the content of the (meth)acrylate monomer having an alicyclic skeleton in the photocurable resin composition of this embodiment is preferably 30 parts by mass or more and 100 parts by mass or less, more preferably 40 parts by mass or more and 100 parts by mass or less, even more preferably 45 parts by mass or more and 100 parts by mass or less, even more preferably 50 parts by mass or more and 100 parts by mass or less, even more preferably 60 parts by mass or more and 100 parts by mass or less, even more preferably 70 parts by mass or more and 100 parts by mass or less, even more preferably 75 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, and even more preferably 90 parts by mass or more and 100 parts by mass or less, when the total content of the (meth)acrylate monomer (A) is taken as 100 parts by mass.

[0023] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the (meth)acrylate monomer (A) preferably contains a (meth)acrylate monomer having a linear hydrocarbon skeleton, more preferably contains one or more selected from the group consisting of 1,12-dodecanediol di(meth)acrylate and dipropylene glycol di(meth)acrylate, and even more preferably contains 1,12-dodecanediol di(meth)acrylate.

[0024] <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.

[0025] 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.

[0026] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the monofunctional (meth)acrylate monomer (A1) preferably contains one or more monomers selected from the group consisting of ethoxylated-o-phenylphenol (meth)acrylate, dicyclopentanyl (meth)acrylate, and isobornyl (meth)acrylate.

[0027] <Difunctional or higher functional (meth)acrylate monomer (A2)> The difunctional or higher functional (meth)acrylate monomer (A2) preferably includes one or more selected from the group consisting of alicyclic difunctional (meth)acrylate monomers and linear difunctional (meth)acrylate monomers.

[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 the occurrence of cracks in the optical molded body.

[0031] 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 is tricyclodecane dimethanol di(meth)acrylate, and even more preferably is tricyclodecane dimethanol dimethacrylate (e.g., DCP, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0032] 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.

[0033] 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.).

[0034] The bifunctional or higher functional (meth)acrylate monomer (A2) preferably has an alicyclic skeleton, from the viewpoint of further reducing the occurrence of cracks in 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 the occurrence of cracks in 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 the occurrence of cracks in the optical molded body. The di- or higher functional (meth)acrylate monomer (A2) more preferably contains 1,12-dodecanediol di(meth)acrylate, and even more preferably contains 1,12-dodecanediol dimethacrylate, from the viewpoint of further reducing the occurrence of cracks in the optical molded body.

[0036] <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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] From the viewpoint of reducing discoloration of the optical molded body, the antioxidant (B) preferably contains one or more antioxidants selected from the group consisting of phenolic antioxidants and thioether antioxidants. From the viewpoint of reducing discoloration of the optical molded body, the antioxidant (B) more preferably contains 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).

[0043] 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, relative to 100 parts by mass of the (meth)acrylate monomer (A).

[0044] 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.

[0045] <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.

[0046] 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.

[0047] 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.

[0048] From the viewpoint of further reducing the occurrence of cracks in 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).

[0049] 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 (meth)acrylate monomer (A), from the viewpoint of further reducing the occurrence of cracks in the optical molded body. 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 (meth)acrylate monomer (A), from the viewpoint of improving the thickness uniformity of the photocurable resin composition when cured. From the viewpoint of further reducing the occurrence of cracks in the optical molded body and 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 even more preferably 3.0 parts by mass or more and 4.5 parts by mass or less, when the content of the (meth)acrylate monomer (A) is taken as 100 parts by mass.

[0050] From the viewpoint of further reducing the occurrence of cracks in 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.

[0051] <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.

[0052] The light stabilizer (D) preferably contains a hindered amine-based light stabilizer from the viewpoint of further improving coloration resistance.

[0053] 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.

[0054] 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).

[0055] From the viewpoint of coloration resistance of the optical molded body, 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 reducing bleed-out, 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 coloration resistance of the optical molded body and the viewpoint of 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.

[0056] <Other Components> The photocurable resin composition may include, as specific examples of other components besides the polymerizable compound (e.g., the (meth)acrylate monomer (A)), 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.

[0057] <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 (meth)acrylate monomer (A)) and, if necessary, other components such as an antioxidant (B), a photopolymerization initiator (C), or a light stabilizer (D) by a conventionally known method.

[0058] <Physical Properties of Photocurable Resin Composition> Next, the physical properties of the photocurable resin composition will be described.

[0059] Regarding the photocurable resin composition of this embodiment, the humidity swelling ratio α1 measured in accordance with the following <humidity-conditioned thermomechanical analysis (humidity-conditioned TMA)> for a cured film produced using the photocurable resin composition according to the following <cured film production conditions> will be described.

[0060] From the viewpoint of being able to reduce the occurrence of cracks in the optical molded body, the humidity swelling ratio α1 is preferably 1.00% or less, more preferably 0.70% or less, even more preferably 0.50% or less, even more preferably 0.40% or less, even more preferably 0.30% or less, even more preferably 0.20% or less, and even more preferably 0.15% or less. From the viewpoint of being able to further reduce the occurrence of cracks in the optical molded body, the humidity swelling ratio α1 is preferably −0.40% or more, more preferably −0.30% or more, even more preferably −0.20% or more, even more preferably −0.15% or more, even more preferably −0.10% or more, even more preferably −0.05% or more, and even more preferably 0.00% or more. From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the humidity swelling rate α1 is preferably −0.40% or more and 1.00% or less, more preferably −0.30% or more and 0.70% or less, even more preferably −0.20% or more and 0.50% or less, even more preferably −0.15% or more and 0.40% or less, even more preferably −0.10% or more and 0.30% or less, even more preferably −0.05% or more and 0.20% or less, and even more preferably 0.00% or more and 0.15% or less.

[0061] <Conditions for preparing a cured film> A 100 μm thick, 100 mm x 100 mm PET film and a 500 μm thick, 100 mm x 100 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 50 mm diameter circular hole were placed on a 2.0 mm thick, 100 mm x 100 mm alkali-free glass in this order. Next, the circular hole was filled with a photocurable resin composition, and then a 100 μm thick, 100 mm x 100 mm PET film and a 2.0 mm thick, 100 mm x 100 mm alkali-free glass were placed on top of the PET film in this order. Next, the resultant was placed on a SUS lab jack to adjust the height. Next, one of the alkali-free glasses was irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes, and then the glass was 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 is allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition is released from the alkali-free glass, PET film, and silicone sheet to obtain a cured film. More specifically, the conditions for producing a cured film of the photocurable resin composition of this embodiment can be the conditions described in the Examples.

[0062] <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> The cured film was cut into a strip of 5 mm width and 15 mm length to prepare a test specimen. The test specimen was subjected to humidity-conditioned thermomechanical analysis (humidity-conditioned TMA) under the following conditions: tensile mode, load: 5 gf, chuck distance: 10 mm, nitrogen atmosphere, and temperature: 65°C (constant). The humidity-conditioned thermomechanical analysis was performed in succession through the following steps S1 to S5. The humidity swelling ratio during the humidity increase step was designated as humidity swelling ratio α1. (S1) A process of maintaining humidity at 0% RH for 30 minutes. (S2) A process of increasing humidity from 0% RH to 90% RH at a humidity increase rate of 5% RH / min (humidification process). (S3) A process of maintaining humidity at 90% RH for 150 minutes. (S4) A process of decreasing humidity from 90% RH to 0% RH at a humidity decrease rate of 5% RH / min (humidification process). (S5) A process of maintaining humidity at 0% RH for 30 minutes.

[0063] Here, in this embodiment, the <humidity-controlled thermomechanical analysis (humidity-controlled TMA)> can be carried out more specifically according to the method described in the examples.

[0064] Next, the humidity swelling ratio α2 measured by the humidity-controlled thermomechanical analysis (humidity-controlled TMA) for a cured film prepared using a photocurable resin composition according to the above-mentioned conditions for preparing a cured film will be described. The humidity swelling ratio in the humidity-dehumidifying step is defined as the humidity swelling ratio α2.

[0065] From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the humidity swelling ratio α2 is preferably 0.00% or less, more preferably −0.010% or less, even more preferably −0.030% or less, even more preferably −0.050% or less, even more preferably −0.10% or less, even more preferably −0.15% or less, and even more preferably −0.20% or less. The lower limit of the humidity swelling ratio α2 is not particularly limited, but from the viewpoint of further reducing the occurrence of cracks in the optical molded body, it is, for example, −1.00% or more, for example, −0.90% or more, for example, −0.80% or more, for example, −0.70% or more, for example, −0.60% or more, for example, −0.55% or more, for example, −0.50% or more. From the viewpoint of further reducing the occurrence of cracks in the optical molded body, the humidity swelling rate α2 is preferably −1.00% or more and 0.00% or less, more preferably −0.90% or more and −0.010% or less, even more preferably −0.80% or more and −0.030% or less, even more preferably −0.70% or more and −0.050% or less, even more preferably −0.60% or more and −0.10% or less, even more preferably −0.55% or more and −0.15% or less, and even more preferably −0.50% or more and −0.20% or less.

[0066] <Uses of Photocurable Resin Composition> Next, uses of the photocurable resin composition will be described.

[0067] The photocurable resin composition of this embodiment can reduce the occurrence of cracks in an optical molded body, and therefore can be used in methods for forming an optical molded body, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, and casting methods. In particular, the photocurable resin composition of this embodiment can be used in casting methods.

[0068] Since the photocurable resin composition of this embodiment can reduce the occurrence of cracks in optical molded bodies, the uses of optical molded bodies molded from the photocurable resin composition are not particularly limited, and the optical molded bodies can be used for a variety of purposes.

[0069] 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.

[0070] 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).

[0071] 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.

[0072] 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 (VR cover displays), cover displays for mixed reality devices (MR cover displays), cover displays for augmented reality devices (AR cover displays), cover displays for cross reality devices (xR cover displays), and cover displays for head-mounted displays (HMD cover displays).

[0073] (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.

[0074] 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.

[0075] 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).

[0076] 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.

[0077] 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).

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] The photocurable resin composition of this embodiment can reduce the occurrence of cracks in optical molded bodies, and therefore can be applied to optical molded bodies having a thickness of 1.0 mm or more.

[0083] (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).

[0084] 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.

[0085] 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.

[0086] First, the materials used in each example are listed. Polymerizable compound: (meth)acrylate monomer (A) Monofunctional (meth)acrylate monomer (A1) 1: OPPEOA (o-Phenylphenoxyethyl acrylate, manufactured by Kunisei Chemical Co., Ltd., monofunctional aromatic cyclic acrylate monomer) Monofunctional (meth)acrylate monomer (A1) 2: FA513AS (dicyclopentanyl acrylate, manufactured by Resonac Corporation, monofunctional alicyclic acrylate monomer) Monofunctional (meth)acrylate monomer (A1) 3: GM81HDA (dicyclopentanyl methacrylate, manufactured by Kunisei Chemical Co., Ltd., monofunctional alicyclic methacrylate monomer) Monofunctional (meth)acrylate monomer (A1) 4: Light Ester IB-X (isobornyl methacrylate, manufactured by Kyoeisha Chemical Co., Ltd., monofunctional alicyclic methacrylate monomer) (hereinafter also referred to as IBX).) Difunctional or higher (meth)acrylate monomer (A2) 1: DCP (tricyclodecane dimethanol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd., bifunctional alicyclic methacrylate) Difunctional or higher (meth)acrylate monomer (A2) 2: DDD (1,12-dodecanediol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd., bifunctional linear methacrylate) Difunctional or higher (meth)acrylate monomer (A2) 3: SR508NS (dipropylene glycol diacrylate, manufactured by Arkema, bifunctional linear acrylate) Antioxidant (B) Antioxidant 1: thioether-based antioxidant (2,2-bis[[3-(dodecylthio)propionic acid]3-(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). Photopolymerization initiator 2: photoradical polymerization initiator (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM Resins, product name: Omnirad TPO H) 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).

[0087] (Examples 1 to 6, 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 the photocurable resin compositions obtained in each example or their cured products were measured using the following methods. The measurement results are shown in Table 1.

[0088] <Measurement of Humidity Swelling Ratio α1> For cured films prepared using the photocurable resin composition of each example according to the <Cured Film Preparation Conditions> below, the humidity swelling ratio α1 was measured according to the <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> below.

[0089] <Conditions for Producing Cured Film> A 100 μm thick, 100 mm × 100 mm PET film (without release treatment, manufactured by Teijin Limited, product name: Melinax S) and a 500 μm thick, 100 mm × 100 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 50 mm diameter circular hole were placed in this order on a 2.0 mm thick, 100 mm × 100 mm alkali-free glass sheet (product name: JIS R 3202 glass plate thread surface, manufactured by Test Piece Co., Ltd.). After filling the circular hole in the silicone sheet with a photocurable resin composition, a 100 μm thick, 100 mm x 100 mm PET film (without release treatment, manufactured by Teijin Limited, product name: Melinax S) and a 2.0 mm thick, 100 mm x 100 mm alkali-free glass (product name: JIS R 3202 glass plate thread surface, manufactured by Test Piece Co., Ltd.) were further placed on top of it in this order. At this time, it was confirmed that there were no air bubbles. Hereinafter, the product obtained by placing the PET film and silicone sheet on the above-mentioned alkali-free glass, filling the circular hole in the silicone sheet with a photocurable resin, and then further placing the PET film and alkali-free glass on top of that may be referred to as a laminate. The resulting laminate was placed on a SUS lab jack and the height was adjusted. 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 irradiating with LED light, the laminate 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.).

[0090] <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> The cured film was cut into a strip of 5 mm width and 15 mm length to prepare a test piece. Using a humidity-conditioned thermomechanical analysis (humidity-conditioned TMA), the test piece was subjected to humidity-conditioned thermomechanical analysis in the following order of <Humidity-Conditioned TMA Measurement Conditions> and <Humidity-Conditioned TMA Measurement Steps>.

[0091] <Measurement conditions for humidity-controlled TMA> Apparatus: Thermomechanical analyzer (product name: TMA 4000SE, manufactured by NETZSCH Japan) Test mode: Tensile mode Load: 5 gf Chuck distance: 10 mm Atmosphere: Nitrogen atmosphere Temperature: 65°C (constant)

[0092] <Measuring steps for humidity-conditioned TMA> The following steps S1 to S5 were performed in succession. The humidity swelling rate in the following humidity increasing step was designated as humidity swelling rate α1 [%]. The humidity swelling rate in the following humidity decreasing step was designated as humidity swelling rate α2 [%]. (S1) A process of maintaining humidity at 0% RH for 30 minutes. (S2) A process of increasing humidity from 0% RH to 90% RH at a humidity increasing rate of 5% RH / min (humidification step). (S3) A process of maintaining humidity at 90% RH for 150 minutes. (S4) A process of decreasing humidity from 90% RH to 0% RH at a humidity decreasing rate of 5% RH / min (humidification step). (S5) A process of maintaining humidity at 0% RH for 30 minutes.

[0093] <Measurement of Humidity Swelling Ratio α2> For cured films produced using the photocurable resin composition of each example according to the above <Cured Film Production Conditions>, the humidity swelling ratio α2 was measured according to the above <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)>.

[0094] <Evaluation of Presence or Absence of Cracks> Optical molded bodies were produced using the photocurable resin composition of each example according to the <Production Conditions for Optical Molded Body> described below. An AR film was vapor-deposited onto the produced optical molded body according to the <Method for Vapor Deposition of AR Film> described below. Next, the optical molded body onto which the AR film had been vapor-deposited was subjected to the <Environmental Test> described below. Thereafter, the appearance of the AR film of the optical molded body was visually observed to evaluate the presence or absence of cracks. This evaluation was performed with n=15. A was assigned to a case where the number of samples in which cracks occurred in the AR film of the optical molded body was 0; B was assigned to a case where the number of samples in which cracks occurred in the AR film of the optical molded body was 1 to 3; and C was assigned to a case where the number of samples in which cracks occurred in the AR film of the optical molded body was 4 or more.

[0095] <Conditions for Producing Optical Molded Body> An optical molded body was produced from a photocurable resin composition using a tape molding method according to the following <Tape Molding Conditions>. A pair of glass molds was placed at a predetermined distance. Tape was attached circumferentially to the outer peripheral surfaces of the glass molds to seal the space between the pair of glass molds. Next, an injection nozzle was inserted into the sealed space, and the photocurable resin composition was injected and filled into the sealed space through the injection nozzle. At this time, care was taken to avoid introducing air bubbles into the sealed space. Thereafter, with the concave surfaces of the pair of glass molds facing 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 from above the pair of glass molds with LED light having a wavelength of 405 nm at 810 mW for 3 minutes using the LED light irradiation device. Next, the pair of glass molds were turned over so that the convex surfaces of the pair of glass molds faced the LED light irradiation device. Subsequently, with the convex surfaces of the pair of glass molds facing the LED light irradiation device, the photocurable resin composition was irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes from above the pair of glass molds using the LED light irradiation device. After irradiating with LED light, the cured product of the photocurable resin composition was allowed to cool at 23°C for 30 minutes. After cooling, the tape was removed and the product was released from the glass mold to obtain an optical molded body. The irradiation intensity of the LED light was measured using an ultraviolet integrating actinometer (product name: UIT-250, manufactured by Ushio Inc.). <Tape molding conditions> A pair of glass molds Spherical glass mold A and spherical glass mold B were arranged so that the center line of spherical glass mold A overlapped with the center line of spherical glass mold B and the concave surface of spherical glass mold A faced the convex surface of spherical glass mold B. Spherical glass mold A: Convex surface radius of curvature: 243 mm, concave surface radius of curvature: 253 mm, thickness: 4.8 mm, diameter: 81 mmφ, double-sided polished spherical glass mold. Spherical glass mold B: Convex surface radius of curvature: 250 mm, concave surface radius of curvature: 216 mm, thickness: 3.6 mm, diameter: 81 mmφ, double-sided polished spherical glass mold. Spacing between glass molds: 3 mm Tape: SLION TAPE 6263, manufactured by Sliontec

[0096] <Method of depositing AR film> The size of the optical molded body was adjusted to a diameter of 75 mm. An AR film was deposited on the convex surface of the optical molded body whose size had been adjusted. The AR film was deposited using an AR deposition device (manufactured by OPTOTECH). ZrO ２ Film 32.5nm, SiO ２ Film 49.7nm, TiO ２ Film 225.3 nm, SiO ２ A 164.5 nm thick film and a 7.0 nm thick hydrophobic film were deposited in this order. During deposition, the temperature was 65±5°C and the vacuum was 5.0×10 －４ The pressure was controlled to be equal to or less than Pa. The hydrophobic film used was Excel CV Pill 1110 (manufactured by OPTOTECH).

[0097] <Environmental Test> The optical molded body on which the AR film was deposited was placed in a thermo-hygrostat chamber at 65° C. and 90% RH. After 500 hours had passed since being placed in the thermo-hygrostat chamber, the optical molded body was taken out of the thermo-hygrostat chamber.

[0098]

[0099] This application claims priority based on Japanese Patent Application No. 2024-012799 filed on January 31, 2024, and Japanese Patent Application No. 2024-069302 filed on April 22, 2024, the disclosures of which are incorporated herein in their entireties.

Claims

1. A photocurable resin composition usable for optical molded articles, wherein a cured film produced using the photocurable resin composition according to the following <Cured Film Production Conditions> has a humidity swelling ratio α1 of 1.00% or less as measured by the following <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)>. <Cured Film Production Conditions> A 100 μm-thick, 100 mm x 100 mm PET film and a 500 μm-thick, 100 mm x 100 mm silicone sheet (material: silicone rubber, hardness: 50 degrees) with a 50 mmφ circular hole are placed in this order on a 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet, the circular hole is filled with the photocurable resin composition, and then the 100 μm-thick, 100 mm x 100 mm PET film and the 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet are placed on top of the 100 μm-thick, 100 mm x 100 mm PET film and the 2.0 mm-thick, 100 mm x 100 mm alkali-free glass sheet. The above-mentioned items are further placed in this order, and this is placed on an SUS lab jack to adjust the height. One of the alkali-free glasses is irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes onto the photocurable resin composition, and then the glass is turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for 3 minutes. The glass is then allowed to cool at 23°C for 30 minutes, and the cured product of the photocurable resin composition is released from the alkali-free glass, the PET film, and the silicone sheet to obtain a cured film. <Humidity-Conditioned Thermomechanical Analysis (Humidity-Conditioned TMA)> The cured film was cut into a strip having a width of 5 mm and a length of 15 mm to prepare a test piece. The test piece was subjected to humidity-conditioned thermomechanical analysis (humidity-conditioned TMA) in a tensile mode with a load of 5 gf, a chuck distance of 10 mm, in a nitrogen atmosphere, and at a constant temperature of 65°C. The test piece was subjected to the following consecutive steps: maintaining the test piece at a humidity of 0% RH for 30 minutes; increasing the humidity from 0% RH to 90% RH at a humidity increase rate of 5% RH / min (humidity increase step); maintaining the test piece at a humidity of 90% RH for 150 minutes; decreasing the humidity from 90% RH to 0% RH at a humidity decrease rate of 5% RH / min (humidity decrease step); and maintaining the test piece at a humidity of 0% RH for 30 minutes. The humidity swelling ratio in the humidity increase step was designated as the humidity swelling ratio α1.

2. The photocurable resin composition according to claim 1, wherein the humidity swelling rate α1 is −0.40% or more.

3. The photocurable resin composition according to claim 1 or 2, wherein the humidity swelling rate in the humidity decreasing step is a humidity swelling rate α2, and in a cured film produced using the photocurable resin composition according to the <cured film production conditions>, the humidity swelling rate α2 measured according to the <humidity-conditioned thermomechanical analysis (humidity-conditioned TMA)> is 0.00% or less.

4. The photocurable resin composition according to any one of claims 1 to 3, which contains a (meth)acrylate monomer.

5. The photocurable resin composition according to claim 4, wherein the (meth)acrylate monomer comprises a methacrylate monomer.

6. A photocurable resin composition according to claim 4 or 5, wherein the (meth)acrylate monomer comprises one or more selected from the group consisting of monofunctional (meth)acrylate monomers and di- or higher functional (meth)acrylate monomers.

7. A photocurable resin composition according to claim 6, wherein the content of the monofunctional (meth)acrylate monomer is 0 parts by mass or more and 100 parts by mass or less, when the total content of the (meth)acrylate monomers is 100 parts by mass.

8. The photocurable resin composition according to any one of claims 4 to 7, wherein the (meth)acrylate monomer includes a (meth)acrylate monomer having an alicyclic skeleton.

9. The photocurable resin composition according to claim 8, wherein the (meth)acrylate monomer having an alicyclic skeleton has one or more skeletons selected from the group consisting of an adamantane skeleton, a norbornane skeleton, and a dicyclopentadiene skeleton.

10. A photocurable resin composition according to claim 8 or 9, wherein the content of the (meth)acrylate monomer having an alicyclic skeleton is 30 parts by mass or more and 100 parts by mass or less, when the total content of the (meth)acrylate monomers is 100 parts by mass.

11. The photocurable resin composition according to any one of claims 4 to 10, wherein the (meth)acrylate monomer comprises a (meth)acrylate monomer having a linear hydrocarbon skeleton.

12. The photocurable resin composition according to any one of claims 1 to 11, further comprising a light stabilizer.

13. The photocurable resin composition according to any one of claims 1 to 12, further comprising an antioxidant.

14. The photocurable resin composition according to any one of claims 1 to 13, further comprising a photopolymerization initiator.

15. The photocurable resin composition according to claim 14, wherein the photopolymerization initiator comprises a photoradical polymerization initiator.

16. A photocurable resin composition according to any one of claims 1 to 15, which can be used in a casting method.

17. The photocurable resin composition according to any one of claims 1 to 16, 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).

18. An optical molded body comprising a cured product of the photocurable resin composition according to any one of claims 1 to 17.

19. The optical molded body of claim 18, wherein the optical molded body comprises a lens.

20. The optical molded body according to claim 19, 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).

21. The optical molded body of claim 18, wherein the optical molded body comprises a cover display.

22. The optical molded body according to claim 21, wherein the cover display comprises one or more types selected from the group consisting of a cover display for a virtual reality device, a cover display for a mixed reality device, a cover display for an augmented reality device, a cover display for a cross reality device, and a cover display for a head-mounted display.

23. The optical molded body according to any one of claims 18 to 22, wherein the maximum thickness is 20.0 mm or less.

24. The optical molded body according to any one of claims 18 to 23, wherein the maximum thickness is 1.0 mm or more.

25. An optical device comprising the optical molded body according to any one of claims 18 to 24.

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