Photocurable resin composition, optical molded product, and method for producing optical molded product

Abstract

Provided is a photocurable resin composition that can be used in an optical molded product, wherein the photocurable resin composition has an organic radical residual ratio of 20.0% or less calculated according to a prescribed method.

Description

Photocurable resin composition, optical molded body, and method for manufacturing optical molded body

[0001] The present invention relates to a photocurable resin composition, an optical molded body, and a method for producing an optical molded body.

[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] A first embodiment of the present invention provides a photocurable resin composition that can reduce coloration of an optical molded product.

[0007] The second embodiment of the present invention provides a method for producing an optical molded body that can reduce coloring of the optical molded body.

[0008] The present inventors conducted extensive research to achieve the object of the first embodiment. As a result, they found that the residual organic radicals in a photocurable resin composition, measured under specific conditions, are related to the coloration of the resulting optical molded body. Based on the above findings, the present inventors conducted further extensive research and found that the coloration of the optical molded body can be reduced by using a photocurable resin composition having an organic radical residual rate of 20.0% or less, thereby completing the first embodiment of the present invention.

[0009] [1A] A photocurable resin composition usable for an optical molded body, wherein the photocurable resin composition has an organic radical residual rate of 20.0% or less, as calculated in accordance with the following <Method for calculating organic radical residual rate>. <Method for calculating organic radical residual rate> The organic radical amount A of a first cured film produced using the photocurable resin composition according to the following <Conditions for producing a cured film> is measured in accordance with the following <Measurement of initial organic radical amount>. ０ and an organic radical amount A of the first cured film measured according to the <Measurement of organic radical amount after heating> described below. １ Using the above, the organic radical remaining rate is calculated by the following formula (1): (1): Organic radical remaining rate (%) = 100 × A １ / A ０ <Conditions for Producing 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. 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. <Measurement of initial organic radical amount> Within 1 hour to 2 hours after the completion of LED light irradiation, 7 mg of a first sample was collected from the first cured film, and 1 hour after the first sample was collected, the amount of organic radicals A at a measurement temperature of 23°C was measured by electron spin resonance (ESR) using the first sample according to the following <ESR measurement conditions>. ０<Measurement of organic radical amount after heating> After the <Measurement of initial organic radical amount> is completed, the temperature of the electron spin resonance apparatus is increased to 120°C over 10 minutes while the first sample is held inside the electron spin resonance apparatus described below, and the first sample is heated at 120°C for 10 minutes. After the heating of the first sample, the amount of organic radicals A at a measurement temperature of 120°C is measured by electron spin resonance (ESR) using the first sample according to the <ESR measurement conditions> described below. １ <ESR measurement conditions> Apparatus: electron spin resonance apparatus Resonance frequency: 9.2 GHz Microwave input: 1 mW Central magnetic field: 327.0 mT Sweep width: ±15 mT Modulation frequency: 100 kHz (modulation width: 1.0 mT) Sweep time: 2 minutes Time constant: 0.03 seconds Sample tube: X-band compatible sample tube with quartz tip External standard: Mn supported on magnesium oxide ２＋ Standard sample External standard scale: 850.0 Measurement temperature: 23°C and 120°C Measurement atmosphere: air Sample: 7 mg [2A] In the <Measurement of organic radical amount after heating>, １ is the normalized amount of organic radicals A calculated by the following formula (2): １Ｓ wherein the normalized organic radical amount A １Ｓ (2): The photocurable resin composition according to the above [1A], wherein the normalized organic radical amount A is 50.0 or less. １Ｓ = (area of ​​the part of the ESR spectrum corresponding to the organic radical) / {(Mn ２＋(area of ​​a portion (second signal) corresponding to (amount) × (sampled amount of the photocurable resin composition)} [3A] The photocurable resin composition according to [1A] or [2A], comprising one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and di- or higher functional (meth)acrylate monomers. [4A] The photocurable resin composition according to [3A], wherein the content of the di- 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 di- or higher functional (meth)acrylate monomer is 100 parts by mass. [5A] The photocurable resin composition according to [3A] or [4A], wherein the mass ratio of the content of the monofunctional (meth)acrylate monomer to the content of the di- or higher functional (meth)acrylate monomer is 0.50 or more and 10.0 or less. [6A] The photocurable resin composition according to any one of [3A] to [5A] above, wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton. [7A] The photocurable resin composition according to any one of [3A] to [6A] above, wherein the difunctional or higher functional (meth)acrylate monomer has an alicyclic skeleton. [8A] The photocurable resin composition according to any one of [3A] to [7A] above, wherein the difunctional or higher functional (meth)acrylate monomer has a straight-chain hydrocarbon skeleton. [9A] The photocurable resin composition according to any one of [1A] to [8A] above, wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> is heated at 120°C for 10 minutes, and has a yellowness index (YI value) of 8.50 or less, as measured in accordance with ASTM E313-73. [10A] The photocurable resin composition according to any one of [1A] to [9A] above, further comprising an antioxidant. [11A] The photocurable resin composition according to any one of [1A] to [10A] above, further comprising a photopolymerization initiator. [12A] The photocurable resin composition according to [11A] above, wherein the photopolymerization initiator comprises a photoradical polymerization initiator. [13A] The photocurable resin composition according to any one of [1A] to [12A] above, further comprising a light stabilizer. [14A] The photocurable resin composition according to any one of [1A] to [13A] above, which can be used in a casting method.[15A] The photocurable resin composition according to any one of [1A] to [14A] 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). [16A] An optical molded body comprising a cured product of the photocurable resin composition according to any one of [1A] to [15A] above. [17A] The optical molded body according to [16A] above, wherein the optical molded body comprises a lens. [18A] The optical molded body according to [17A] above, 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). [19A] The optical molded body according to [16A], wherein the optical molded body includes a cover display. [20A] The optical molded body according to [19A], wherein the cover display includes 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. [21A] The optical molded body according to any one of [16A] to [20A], wherein the maximum thickness part is 20 mm or less. [22A] The optical molded body according to any one of [16A] to [21A], wherein the maximum thickness part is 1.0 mm or more.

[0010] Furthermore, the present inventors conducted extensive research to achieve the object of the second embodiment. As a result, they found that in a manufacturing method of an optical molded body, treatment of the optical molded body after photocuring is related to the coloring of the obtained optical molded body. Based on the above findings, the present inventors conducted further extensive research and found that coloring of the optical molded body can be reduced by including a step of heating the optical molded body after photocuring in the manufacturing method of the optical molded body, thereby completing the second embodiment of the present invention.

[0011] [1B] A method for producing an optical molded body, comprising: a curing step of irradiating a photocurable resin composition with light to cure the composition, thereby producing an optical molded body; and a heating step of heating the optical molded body to reduce coloration of the optical molded body. [2B] The method for producing an optical molded body according to [1B], wherein the glass transition temperature of the photocurable resin composition is 100°C or higher. [3B] The method for producing an optical molded body according to [1B] or [2B], wherein the heating step heats the optical molded body to a temperature of 80°C or higher. [4B] The method for producing an optical molded body according to any of [1B] to [3B], wherein the heating step heats the optical molded body to a temperature lower than the glass transition temperature of the photocurable resin composition + 20°C. [5B] The method for producing an optical molded body according to any of [1B] to [4B], wherein the heating step heats the optical molded body for a heating time of 1 minute or longer. [6B] Yellowness index YI measured according to ASTM E313-73 of the optical molded body before the heating step １ Yellowness index YI measured according to ASTM E313-73 of the optical molded body after the heating step ２ The ratio of YI ２ / YI １is 0.900 or less. [7B] The method for producing an optical molded body according to any one of [1B] to [5B] above, comprising a step of molding the optical molded body by a casting method. [8B] The method for producing an optical molded body according to any one of [1B] to [7B] above, wherein the photocurable resin composition contains one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and difunctional or higher functional (meth)acrylate monomers. [9B] The method for producing an optical molded body according to [8B] above, wherein the content of the difunctional or higher functional (meth)acrylate monomer in the photocurable resin composition is 5.0 parts by mass or more and 150 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. [10B] The method for producing an optical molded body according to [8B] or [9B], wherein the photocurable resin composition has a mass ratio of the content of the monofunctional (meth)acrylate monomer to the content of the difunctional or higher functional (meth)acrylate monomer of 0.50 or more and 10.0 or less. [11B] The method for producing an optical molded body according to any of [8B] to [10B], wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton. [12B] The method for producing an optical molded body according to any of [8B] to [11B], wherein the difunctional or higher functional (meth)acrylate monomer has an alicyclic skeleton. [13B] The method for producing an optical molded body according to any of [8B] to [12B], wherein the difunctional or higher functional (meth)acrylate monomer has a linear hydrocarbon skeleton. [14B] The method for producing an optical molded body according to any of [1B] to [13B], wherein the photocurable resin composition further contains an antioxidant. [15B] The method for producing an optical molded body according to any one of [1B] to [14B], wherein the photocurable resin composition further contains a photopolymerization initiator. [16B] The method for producing an optical molded body according to [15B], wherein the photopolymerization initiator comprises a photoradical polymerization initiator. [17B] The method for producing an optical molded body according to any one of [1B] to [16B], wherein the photocurable resin composition further contains a light stabilizer.[18B] The method for producing an optical molded body according to any one of [1B] to [17B], wherein the optical molded body includes a lens. [19B] The method for producing an optical molded body according to [18B], wherein the lens 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). [20B] The method for producing an optical molded body according to any one of [1B] to [19B], wherein the maximum thickness of the optical molded body is 20 mm or less. [21B] The method for producing an optical molded body according to any one of [1B] to [20B], wherein the maximum thickness of the optical molded body is 1.0 mm or more.

[0012] According to the first embodiment of the present invention, it is possible to provide a photocurable resin composition that can reduce coloring of an optical molded body.

[0013] Furthermore, according to the second embodiment of the present invention, it is possible to provide a method for producing an optical molded body that can reduce coloring of the optical molded body.

[0014] 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 in each 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 "at least" or "at most," and includes both the upper and lower limits.

[0015] <<First Embodiment>> Hereinafter, a photocurable resin composition and an optical molded body according to a first embodiment of the present invention will be described.

[0016] (Photocurable Resin Composition) In the first embodiment, the photocurable resin composition (hereinafter also referred to simply as "resin composition") is a photocurable resin composition that can be used for an optical molded body. The photocurable resin composition of the first embodiment has an organic radical residual rate of 20.0% or less, calculated according to the following <Method for calculating organic radical residual rate>. <Method for calculating organic radical residual rate> The organic radical amount A of a first cured film produced using the photocurable resin composition according to the following <Conditions for producing a cured film> is measured according to the following <Measurement of initial organic radical amount>. ０ and an organic radical amount A of the first cured film measured according to the <Measurement of organic radical amount after heating> described below. １ Using the above, the organic radical remaining rate is calculated by the following formula (3): (3): Organic radical remaining rate (%) = 100 × A １ / A ０ <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. Next, the circular hole was filled with a photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass was placed on top of it. Next, this was placed on a SUS lab jack to adjust the height. Next, 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, and 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 glass 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. <Measurement of initial organic radical amount> Within 1 to 2 hours after the completion of LED light irradiation, 7 mg of a first sample was collected from the first cured film. One hour after the first sample was collected, the organic radical amount A at a measurement temperature of 23°C was measured using the first sample by electron spin resonance (ESR) under the following <ESR measurement conditions>. ０<Measurement of organic radical amount after heating> After the <Measurement of initial organic radical amount> is completed, the temperature of the electron spin resonance apparatus described below is raised to 120°C over 10 minutes while the first sample is held inside the electron spin resonance apparatus described below, and the first sample is heated at 120°C for 10 minutes. After the first sample is heated, the organic radical amount A at a measurement temperature of 120°C is measured by electron spin resonance (ESR) using the first sample according to the <ESR measurement conditions> described below. １ <ESR measurement conditions> Apparatus: electron spin resonance apparatus Resonance frequency: 9.2 GHz Microwave input: 1 mW Central magnetic field: 327.0 mT Sweep width: ±15 mT Modulation frequency: 100 kHz (modulation width: 1.0 mT) Sweep time: 2 minutes Time constant: 0.03 seconds Sample tube: X-band compatible sample tube with quartz tip External standard: Mn supported on magnesium oxide ２＋ Standard sample External standard scale: 850.0 Measurement temperature: 23°C and 120°C Measurement atmosphere: air Sample: 7 mg The photocurable resin composition of the first embodiment has the above-mentioned configuration, which can reduce coloring of the optical molded body.

[0017] 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 coloration of the optical molded body.

[0018] 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.

[0019] 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.

[0020] <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 further reducing the coloration of the optical molded body, the radically polymerizable functional group may be, for example, a (meth)acryloyl group. From the viewpoint of further reducing the coloration of the optical molded body, the polymerizable compound preferably contains a (meth)acrylate monomer (A).

[0021] <(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.

[0022] 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).

[0023] In the photocurable resin composition of the first embodiment, the content of the difunctional or higher (meth)acrylate monomer (A2) is preferably 5.0 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 12 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 18 parts by mass or more, 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, from the viewpoint of improving crack resistance during molding of the optical molded body. In terms of further reducing coloration of the optical molded body, the content of the difunctional or higher (meth)acrylate monomer (A2) is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 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. From the viewpoint of improving the crack resistance during molding of the optical molded body and from the viewpoint of further reducing the coloring of the optical molded body, the content of the difunctional or higher (meth)acrylate monomer (A2) 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.

[0024] In the photocurable resin composition of the first 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, from the viewpoint of further reducing the coloration of the optical molded body, preferably from 0.50 to 10.0, more preferably from 1.00 to 8.00, even more preferably from 1.50 to 6.00, even more preferably from 1.80 to 5.00, and even more preferably from 2.00 to 4.50.

[0025] <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.

[0026] 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.

[0027] From the viewpoint of further reducing the coloration of the optical molded body, the monofunctional (meth)acrylate monomer (A1) more preferably includes one or more selected from the group consisting of lauryl (meth)acrylate and dicyclopentanyl (meth)acrylate.

[0028] The monofunctional (meth)acrylate monomer (A1) preferably has an alicyclic skeleton, from the viewpoint of further reducing coloration 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 coloration of the optical molded body.

[0029] <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.

[0030] 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.

[0031] 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.

[0032] 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.).

[0033] 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.

[0034] 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.).

[0035] 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.

[0036] 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.

[0037] 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.

[0038] <Antioxidant (B)> The photocurable resin composition of the first 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] From the viewpoint of further reducing the coloration 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 further reducing the coloration 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).

[0045] The content of the antioxidant (B) in the photocurable resin composition of the first 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), from the viewpoint of further reducing the coloration of the optical molded body.

[0046] 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 mass%, the content of the antioxidant (B) in the photocurable resin composition of the first embodiment is, from the viewpoint of further reducing coloration of the optical molded body, preferably 0.010 mass% or more and 5.0 mass% or less, more preferably 0.050 mass% or more and 4.0 mass% or less, even more preferably 0.10 mass% or more and 3.0 mass% or less, even more preferably 0.50 mass% or more and 2.0 mass% or less, and even more preferably 0.90 mass% or more and 1.0 mass% or less.

[0047] <Photopolymerization initiator (C)> The photocurable resin composition of the first embodiment may further contain a photopolymerization initiator (C). The photopolymerization initiator (C) is not particularly limited, and a known polymerization initiator can be used.

[0048] 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.

[0049] 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.

[0050] From the viewpoint of further reducing coloration 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).

[0051] The content of the photopolymerization initiator (C) in the photocurable resin composition of the first 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, relative to 100 parts by mass of the (meth)acrylate monomer (A), from the viewpoint of improving the curability of the photocurable resin composition. The content of the photopolymerization initiator (C) in the photocurable resin composition of the first 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, relative to 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. The content of the photopolymerization initiator (C) in the photocurable resin composition of the first 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, relative to 100 parts by mass of the (meth)acrylate monomer (A).

[0052] 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 mass%, the content of the photopolymerization initiator (C) in the photocurable resin composition of the first embodiment is preferably 0.10 mass% or more and 10 mass% or less, more preferably 1.0 mass% or more and 8.0 mass% or less, even more preferably 2.0 mass% or more and 6.0 mass% or less, even more preferably 3.0 mass% or more and 5.0 mass% or less, and even more preferably 3.5 mass% or more and 4.0 mass% or less, from the viewpoint of further reducing coloration of the optical molded body.

[0053] <Light Stabilizer (D)> The photocurable resin composition of the first 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 coloring resistance of the photocurable resin composition can be improved.

[0054] The light stabilizer (D) preferably contains a hindered amine-based light stabilizer from the viewpoint of further improving coloration resistance.

[0055] 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.

[0056] 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).

[0057] The content of the light stabilizer (D) in the photocurable resin composition of the first 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 further reducing coloration of the optical molded body. The content of the light stabilizer (D) in the photocurable resin composition of the first 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. 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 mass%, the content of the light stabilizer (D) in the photocurable resin composition of the first embodiment is, from the viewpoint of further reducing coloration of the optical molded body and reducing bleed-out, preferably 0.0010 mass% or more and 1.00 mass% or less, more preferably 0.0050 mass% or more and 0.60 mass% or less, even more preferably 0.010 mass% or more and 0.50 mass% or less, even more preferably 0.050 mass% or more and 0.40 mass% or less, and even more preferably 0.090 mass% or more and 0.30 mass% or less.

[0058] <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.

[0059] <Method for producing photocurable resin composition> The photocurable resin composition according to the first embodiment of the present invention can be obtained by mixing a polymerizable compound (for example, 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.

[0060] <Physical Properties of Photocurable Resin Composition> Next, the physical properties of the photocurable resin composition will be described.

[0061] Regarding the photocurable resin composition of the first embodiment, the organic radical residual ratio calculated in accordance with the following <Method for calculating organic radical residual ratio (120°C, 10 minutes)> will be described. Note that, hereinafter, the organic radical residual ratio measured in accordance with the following <Organic radical measurement (120°C, 10 minutes)> when the cured film is heated at 120°C for 10 minutes is referred to as the organic radical residual ratio R １０ Also called.

[0062] Organic radical remaining rate R １０ From the viewpoint of reducing coloration of the optical molded body, the organic radical residual ratio R is 20.0% or less, preferably 10.0% or less, more preferably 5.00% or less, even more preferably 4.00% or less, even more preferably 3.00% or less, even more preferably 2.50% or less, even more preferably 2.00% or less, even more preferably 1.50% or less, even more preferably 1.00% or less, even more preferably 0.50% or less, and even more preferably 0.10% or less. １０ The lower limit of the organic radical residual ratio R is not particularly limited, but may be, for example, 0.00% or more. １０From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00% or more and 20.0% or less, more preferably 0.00% or more and 10.0% or less, even more preferably 0.00% or more and 5.00% or less, even more preferably 0.00% or more and 4.00% or less, even more preferably 0.00% or more and 3.00% or less, even more preferably 0.00% or more and 2.50% or less, even more preferably 0.00% or more and 2.00% or less, even more preferably 0.00% or more and 1.50% or less, even more preferably 0.00% or more and 1.00% or less, even more preferably 0.00% or more and 0.50% or less, and even more preferably 0.00% or more and 0.10% or less.

[0063] <Method for calculating the residual organic radical ratio (120°C, 10 minutes)> The amount of organic radicals measured in accordance with the <Initial organic radical amount measurement> below for a first cured film produced using a photocurable resin composition according to the <Cured film production conditions> below was used to calculate the residual organic radical ratio A. ０ The amount of organic radicals in the first cured film measured according to the following <Measurement of organic radical amount after heating (120°C, 10 minutes)> is referred to as organic radical amount A. １ The amount of organic radicals A ０ and the amount of organic radicals A １ Using the above, the organic radical remaining rate R is calculated by the following formula (4). １０ (4): Organic radical remaining rate R １０ (%) = 100 x A １ / A ０

[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. Next, the circular hole was filled with a photocurable resin composition, and then a 0.7 mm thick, 50 mm x 50 mm alkali-free glass was placed on top of it. Next, this was placed on a SUS lab jack to adjust the height. Next, 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, and 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 glass 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. More specifically, the conditions for producing a cured film of the photocurable resin composition of the first embodiment may be the conditions described in the examples of the first embodiment.

[0065] <Measurement of initial organic radical amount> Within 1 hour to 2 hours after the completion of LED light irradiation, 7 mg of a first sample was collected from the first cured film. One hour after the first sample was collected, the amount of organic radicals A at a measurement temperature of 23°C was measured using the first sample by electron spin resonance (ESR). ０ Here, in the first embodiment, <measurement of initial organic radical amount> can be carried out more specifically according to the method described in the examples of the first embodiment.

[0066] In the above <Measurement of the initial amount of organic radicals>, the amount of organic radicals A ０ is the normalized organic radical amount A calculated using the following formula (5): ０Ｓ (5): Normalized organic radical amount A ０Ｓ = (area of ​​the part of the ESR spectrum corresponding to the organic radical in <Measurement of the amount of initial organic radical>) / {(Mn of the ESR spectrum in <Measurement of the amount of initial organic radical>)} ２＋ (area of ​​the portion (second signal) corresponding to (1) × (sampling amount of the first sample))

[0067] <Measurement of organic radical amount after heating (120°C, 10 minutes)> After the above <Measurement of initial organic radical amount> is completed, the temperature of the electron spin resonance apparatus described below is raised to 120°C over 10 minutes while the first sample is held inside the electron spin resonance apparatus described below. After the temperature is raised, the first sample is heated at 120°C for 10 minutes. After heating the first sample, the organic radical amount A at the measurement temperature of 120°C is measured by electron spin resonance (ESR) using the first sample. １ Here, in the first embodiment, <Measurement of the amount of organic radicals after heating (120° C., 10 minutes)> can be carried out more specifically according to the method described in the examples of the first embodiment.

[0068] In the above <Measurement of organic radical amount after heating (120°C, 10 minutes)>, the organic radical amount A １ is the normalized amount of organic radicals A calculated using the following formula (6): １Ｓ (6): Normalized organic radical amount A １Ｓ = (area of ​​the part corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 10 minutes)>) / {(Mn of the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 10 minutes)>)} ２＋ (area of ​​the portion (second signal) corresponding to (1) × (sampling amount of the first sample))

[0069] Normalized organic radical amount A １Ｓ From the viewpoint of further reducing the coloring of the optical molded body, the normalized organic radical amount A is preferably 75.0 or less, more preferably 50.0 or less, even more preferably 40.0 or less, even more preferably 30.0 or less, even more preferably 25.0 or less, even more preferably 10.0 or less, even more preferably 5.00 or less, even more preferably 4.00 or less, even more preferably 3.00 or less, even more preferably 2.00 or less, and even more preferably 1.00 or less. １Ｓ is not particularly limited, but may be, for example, 0.00 or more. １ＳFrom the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00 or more and 75.0 or less, more preferably 0.00 or more and 50.0 or less, even more preferably 0.00 or more and 40.0 or less, even more preferably 0.00 or more and 30.0 or less, even more preferably 0.00 or more and 25.0 or less, even more preferably 0.00 or more and 10.0 or less, even more preferably 0.00 or more and 5.00 or less, even more preferably 0.00 or more and 4.00 or less, even more preferably 0.00 or more and 3.00 or less, even more preferably 0.00 or more and 2.00 or less, and even more preferably 0.00 or more and 1.00 or less.

[0070] Regarding the photocurable resin composition of the first embodiment, the organic radical residual ratio calculated in accordance with the following <Method for calculating organic radical residual ratio (120°C, 30 minutes)> will be described. Note that, hereinafter, the organic radical residual ratio measured in accordance with the following <Organic radical measurement (120°C, 30 minutes)> when the cured film is heated at 120°C for 30 minutes is referred to as the organic radical residual ratio R ３０ Also called.

[0071] Organic radical remaining rate R ３０ From the viewpoint of further reducing the coloring of the optical molded body, the organic radical residual ratio R is preferably 12.0% or less, more preferably 10.0% or less, even more preferably 5.0% or less, even more preferably 2.0% or less, and even more preferably 1.0% or less. ３０ The lower limit of the organic radical residual ratio R is not particularly limited, but may be, for example, 0.00% or more. ３０ From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00% or more and 12.0% or less, more preferably 0.00% or more and 10.0% or less, even more preferably 0.00% or more and 5.0% or less, even more preferably 0.00% or more and 2.0% or less, and even more preferably 0.00% or more and 1.0% or less.

[0072] <Method for calculating the residual organic radical ratio (120°C, 30 minutes)> The amount of organic radicals measured in accordance with the above <Measurement of initial organic radical amount (second cured film)> for a second cured film produced using a photocurable resin composition according to the above <Conditions for producing a cured film> was defined as organic radical amount A. ２The amount of organic radicals in the second cured film measured according to the following <Measurement of organic radical amount after heating (120°C, 30 minutes)> is referred to as organic radical amount A. ３ The amount of organic radicals A ２ and the amount of organic radicals A ３ and the organic radical remaining rate R is calculated by the following formula (7). ３０ (7): Organic radical remaining rate R ３０ (%) = 100 x A ３ / A ２

[0073] <Measurement of initial organic radical amount (second cured film)> Within 1 hour to 2 hours after the completion of LED light irradiation, 7 mg of a second sample was collected from the second cured film. One hour after the second sample was collected, the organic radical amount A at a measurement temperature of 23°C was measured using the second sample by electron spin resonance (ESR). ２ Here, in the first embodiment, <Measurement of initial organic radical amount (second cured film)> can be carried out more specifically according to the method described in the examples of the first embodiment.

[0074] In the above <Measurement of Initial Organic Radical Amount (Second Cured Film)>, the organic radical amount A ２ is the normalized amount of organic radicals A calculated using the following formula (8): ２Ｓ (8): Normalized organic radical amount A ２Ｓ = (area of ​​the portion corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of initial organic radicals (second cured film)>) / {(Mn ２＋ (area of ​​the portion (second signal) corresponding to (2) × (sampling amount of the second sample))

[0075] <Measurement of organic radical amount after heating (120°C, 30 minutes)> After the completion of the above <Measurement of initial organic radical amount (second cured film)>, the temperature of the electron spin resonance apparatus is raised to 120°C over 10 minutes while the second sample is held inside the electron spin resonance apparatus. After the temperature is raised, the second sample is heated at 120°C for 30 minutes. After heating the second sample, the organic radical amount A at the measurement temperature of 120°C is measured by electron spin resonance (ESR) using the second sample. ３ Here, in the first embodiment, <Measurement of the amount of organic radicals after heating (120° C., 30 minutes)> can be carried out more specifically according to the method described in the examples of the first embodiment.

[0076] In the above <Measurement of organic radical amount after heating (120°C, 30 minutes)>, the organic radical amount A ３ is the normalized amount of organic radicals A calculated using the following formula (9): ３Ｓ (9): Normalized organic radical amount A ３Ｓ = (area of ​​the part corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 30 minutes)>) / {(Mn of the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 30 minutes)>)} ２＋ (area of ​​the portion (second signal) corresponding to (2) × (sampling amount of the second sample))

[0077] Normalized organic radical amount A ３Ｓ From the viewpoint of further reducing the coloring of the optical molded body, the normalized organic radical amount A is preferably 30.0 or less, more preferably 20.0 or less, more preferably 10.0 or less, more preferably 5.00 or less, more preferably 4.00 or less, more preferably 3.00 or less, more preferably 2.00 or less, and more preferably 1.00 or less. ３Ｓ is not particularly limited, but may be, for example, 0.00 or more. ３ＳFrom the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00 or more and 30.0 or less, more preferably 0.00 or more and 20.0 or less, even more preferably 0.00 or more and 10.0 or less, even more preferably 0.00 or more and 5.00 or less, even more preferably 0.00 or more and 4.00 or less, even more preferably 0.00 or more and 3.00 or less, even more preferably 0.00 or more and 2.00 or less, and even more preferably 0.00 or more and 1.00 or less.

[0078] In the photocurable resin composition of the first embodiment, a cured film prepared using the photocurable resin composition according to the above <Cured film preparation conditions> is heated at 120°C for 10 minutes, and the yellowness index (YI value) measured in accordance with ASTM E313-73 is described below. Note that, hereinafter, the YI value when the cured film is heated at 120°C for 10 minutes is referred to as the YI value YI １０ Also called.

[0079] YI value YI １０ From the viewpoint of further reducing the coloring of the optical molded body, the YI value is preferably 8.50 or less, more preferably 8.00 or less, even more preferably 7.50 or less, even more preferably 7.00 or less, even more preferably 6.50 or less, even more preferably 6.00 or less, even more preferably 5.50 or less, even more preferably 5.00 or less, even more preferably 4.00 or less, even more preferably 3.00 or less, even more preferably 2.50 or less, and even more preferably 2.00 or less. １０ The lower limit of the YI value is not particularly limited, but may be, for example, 0.00 or more. １０ From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00 or more and 8.50 or less, more preferably 0.00 or more and 8.00 or less, even more preferably 0.00 or more and 7.50 or less, even more preferably 0.00 or more and 7.00 or less, even more preferably 0.00 or more and 6.50 or less, even more preferably 0.00 or more and 6.00 or less, even more preferably 0.00 or more and 5.50 or less, even more preferably 0.00 or more and 5.00 or less, even more preferably 0.00 or more and 4.00 or less, even more preferably 0.00 or more and 3.00 or less, even more preferably 0.00 or more and 2.50 or less, and even more preferably 0.00 or more and 2.00 or less.

[0080] In the photocurable resin composition of the first embodiment, a cured film prepared using the photocurable resin composition according to the above <Cured film preparation conditions> is heated at 120°C for 30 minutes, and the yellowness index (YI value) measured in accordance with ASTM E313-73 is described below. Note that, hereinafter, the YI value when the cured film is heated at 120°C for 30 minutes is referred to as the YI value YI ３０ Also called.

[0081] YI value YI ３０ From the viewpoint of further reducing the coloring of the optical molded body, the YI value is preferably 5.00 or less, more preferably 4.50 or less, even more preferably 4.00 or less, even more preferably 3.50 or less, even more preferably 3.00 or less, even more preferably 2.50 or less, and even more preferably 2.00 or less. ３０ The lower limit of the YI value is not particularly limited, but may be, for example, 0.00 or more. ３０ From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.00 or more and 5.00 or less, more preferably 0.00 or more and 4.50 or less, even more preferably 0.00 or more and 4.00 or less, even more preferably 0.00 or more and 3.50 or less, even more preferably 0.00 or more and 3.00 or less, even more preferably 0.00 or more and 2.50 or less, and even more preferably 0.00 or more and 2.00 or less.

[0082] <Uses of Photocurable Resin Composition> Next, uses of the photocurable resin composition will be described.

[0083] The photocurable resin composition of the first embodiment can reduce coloration 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 methods. In particular, the photocurable resin composition of the first embodiment can be used in casting methods.

[0084] The photocurable resin composition of the first embodiment can reduce coloration 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.

[0085] The photocurable resin composition of the first embodiment can be preferably used for, for example, a lens, which may include 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.

[0086] The photocurable resin composition of the first 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).

[0087] The photocurable resin composition of the first 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.

[0088] The photocurable resin composition of the first 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).

[0089] (Optical Molded Body) The optical molded body of the first embodiment includes a cured product of the photocurable resin composition of the first embodiment. The optical molded body of the first embodiment can be manufactured using the photocurable resin composition of the first embodiment. The optical molded body can be manufactured from the photocurable resin composition of the first embodiment by any method, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, or casting.

[0090] The optical molded body of the first 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.

[0091] The lens of the first 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).

[0092] The optical molded body of the first 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.

[0093] The cover display of the first 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).

[0094] 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.

[0095] For example, the optical molded body of the first 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.

[0096] For example, the optical molded body of the first 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.

[0097] For example, the optical molded body of the first 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.

[0098] The photocurable resin composition of the first embodiment can reduce coloring of the optical molded body, and therefore can be applied to optical molded bodies having a thickness of 1.0 mm or more.

[0099] (Optical Device) The optical device of the first embodiment includes the optical molded body of the first embodiment. The type of the optical device of the first embodiment is not particularly limited. Examples of the optical device of the first 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).

[0100] While the first embodiment of the present invention has 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 first embodiment, and modifications and improvements that do not impair the effects of the present invention are included in the present invention.

[0101] Second Embodiment Hereinafter, a method for producing an optical molded body according to a second embodiment of the present invention will be described.

[0102] [Method for Manufacturing Optical Molded Body] Hereinafter, each step of the manufacturing method according to the second embodiment, and raw materials and the like used in the manufacturing method according to the second embodiment will be described.

[0103] The method for producing an optical molded body according to the second embodiment includes the following steps: Curing step: A photocurable resin composition is irradiated with light to cure it, thereby producing an optical molded body. Heating step: The optical molded body is heated to reduce coloration of the optical molded body. The method for producing an optical molded body according to the second embodiment has the above-described configuration, and therefore can reduce coloration of the optical molded body.

[0104] <Curing Step> In the curing step, the photocurable resin composition is irradiated with light to cure it, thereby producing an optical molded body. The type and shape of the apparatus used in the curing step are not particularly limited, as they vary appropriately depending on the properties of the photocurable resin composition used in the optical molded body or the shape of the optical molded body. In addition, the curing conditions in the curing step (wavelength of the irradiated light, intensity of the irradiated light, irradiation time, or atmosphere during irradiation (temperature, humidity, atmospheric pressure, type of gas, etc.)) are not particularly limited, as they vary appropriately depending on the properties of the photocurable resin composition used in the optical molded body or the shape of the optical molded body.

[0105] The optical molded body of the second embodiment is preferably obtained by irradiating the photocurable resin composition of the second embodiment with LED light to polymerize and cure the photocurable resin composition.

[0106] The LED light may be, for example, ultraviolet light. Examples of ultraviolet light include UVC (Ultraviolet C) with a wavelength of 200 to 280 nm, UVB (Ultraviolet B) with a wavelength of 280 to 315 nm, and UVA (Ultraviolet A) with a wavelength of 315 to 405 nm. When ultraviolet light is used, light sources such as sunlight, a chemical lamp, a mercury lamp, a metal halide lamp, or a UVLED can be used.

[0107] From the viewpoint of improving the appearance of the obtained optical molded body, the irradiation intensity of the ultraviolet irradiation is preferably from 500 mW to 1000 mW, more preferably from 700 mW to 950 mW, even more preferably from 750 mW to 900 mW, and even more preferably from 800 mW to 850 mW. The irradiation intensity of the ultraviolet irradiation refers to the irradiation intensity of ultraviolet light.

[0108] From the viewpoint of improving the appearance of the obtained optical molded body, the cumulative light amount of ultraviolet irradiation is preferably from 100 J to 500 J, more preferably from 150 J to 400 J, even more preferably from 200 J to 350 J, and still more preferably from 250 J to 300 J. The cumulative light amount of ultraviolet irradiation represents the total cumulative light amount of ultraviolet rays.

[0109] <Heating Step> In the heating step, the optical molded body is heated to reduce coloration of the optical molded body.

[0110] The reason why heating an optical molded body can reduce coloration of the optical molded body is not entirely clear, but the following reason is presumed. It is believed that organic radicals generated when the photocurable resin composition is cured may remain in the optical molded body after the curing step. It is believed that these remaining organic radicals increase the coloration of the optical molded body. Here, it is believed that heating the optical molded body after the curing step reduces the amount of remaining organic radicals in the optical molded body or chemical structures generated due to the remaining organic radicals. For this reason, it is believed that heating the optical molded body after the curing step can reduce the coloration of the optical molded body.

[0111] In the heating step, the type and shape of the device used in the heating step are not particularly limited, as they change appropriately depending on the properties of the photocurable resin composition used for the optical molded body, the shape of the optical molded body, etc. Furthermore, the heating conditions in the heating step (heating means, heating temperature, heating time, temperature increase rate, temperature decrease rate, or atmosphere during heating (temperature, humidity, atmospheric pressure, type of gas, etc.)) are not particularly limited, as they change appropriately depending on the properties of the photocurable resin composition used for the optical molded body, the shape of the optical molded body, etc.

[0112] In the heating step, the heating temperature at which the optical molded body is heated is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, even more preferably 110°C or higher, and even more preferably 115°C or higher, from the viewpoint of further reducing coloration of the optical molded body.

[0113] In the heating step, the heating temperature at which the optical molded body is heated is preferably lower than the glass transition temperature Tg of the photocurable resin composition + 20° C., from the viewpoint of further reducing deformation of the optical molded body. From another perspective, the heating temperature at which the optical molded body is heated in the heating step is preferably lower than the glass transition temperature Tg of the optical molded body + 20° C., from the viewpoint of further reducing deformation of the optical molded body.

[0114] For example, when the glass transition temperature Tg of the photocurable resin composition is X [°C], the heating temperature at which the optical molded body is heated in the heating step is, from the viewpoint of reducing deformation of the optical molded body, preferably less than (X + 20) [°C], more preferably less than (X + 10) [°C], even more preferably less than (X + 5) [°C], still more preferably less than X [°C], still more preferably less than (X - 3) [°C], still more preferably less than (X - 5) [°C], still more preferably less than (X - 7) [°C], and still more preferably less than (X - 10) [°C].

[0115] In the heating step, from the viewpoint of further reducing coloration of the optical molded body, when the glass transition temperature Tg of the photocurable resin composition is X [°C], the temperature to which the optical molded body is heated is preferably 80°C or more and less than (X + 20) [°C], more preferably 90°C or more and less than (X + 10) [°C], even more preferably 100°C or more and less than (X + 5) [°C], even more preferably 110°C or more and less than X [°C], even more preferably 115°C or more and less than (X - 3) [°C], even more preferably 115°C or more and less than (X - 5) [°C], even more preferably 115°C or more and less than (X - 7) [°C], and even more preferably 115°C or more and less than (X - 10) [°C].

[0116] In the heating step, the heating time for heating the optical molded body is preferably 1 minute or more, more preferably 5 minutes or more, even more preferably 10 minutes or more, even more preferably 20 minutes or more, even more preferably 30 minutes or more, even more preferably 40 minutes or more, even more preferably 50 minutes or more, and even more preferably 55 minutes or more, from the viewpoint of further reducing the coloration of the optical molded body. In the heating step, the upper limit of the heating time for heating the optical molded body is not particularly limited, but may be, for example, 120 minutes or less, or may be 90 minutes or less. In the heating step, the heating time for heating the optical molded body is preferably 1 minute or more and 120 minutes or less, more preferably 5 minutes or more and 120 minutes or less, even more preferably 10 minutes or more and 120 minutes or less, even more preferably 20 minutes or more and 120 minutes or less, even more preferably 30 minutes or more and 120 minutes or less, even more preferably 40 minutes or more and 90 minutes or less, even more preferably 50 minutes or more and 90 minutes or less, and even more preferably 55 minutes or more and 90 minutes or less, from the viewpoint of further reducing the coloration of the optical molded body.

[0117] Yellowness index (YI) of the optical molded body before the heating process measured in accordance with ASTM E313-73 １ Yellowness index YI measured according to ASTM E313-73 of the optical molded body after the heating process ２ The ratio of YI ２ / YI １ From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.900 or less, more preferably 0.800 or less, even more preferably 0.700 or less, even more preferably 0.650 or less, even more preferably 0.600 or less, even more preferably 0.500 or less, even more preferably 0.400 or less, even more preferably 0.350 or less, even more preferably 0.300 or less, even more preferably 0.250 or less, and even more preferably 0.200 or less.

[0118] Yellowness index (YI) of the optical molded body before the heating process measured in accordance with ASTM E313-73 １ Yellowness index YI measured according to ASTM E313-73 of the optical molded body after the heating process ２ The ratio of YI ２ / YI １ The lower limit of is not particularly limited, but may be, for example, 0.000 or more, 0.001 or more, 0.010 or more, 0.050 or more, or 0.100 or more.

[0119] Yellowness index (YI) of the optical molded body before the heating process measured in accordance with ASTM E313-73 １ Yellowness index YI measured according to ASTM E313-73 of the optical molded body after the heating process ２ The ratio of YI ２ / YI １From the viewpoint of further reducing the coloring of the optical molded body, is preferably 0.000 or more and 0.900 or less, more preferably 0.000 or more and 0.800 or less, even more preferably 0.000 or more and 0.700 or less, even more preferably 0.000 or more and 0.650 or less, even more preferably 0.000 or more and 0.600 or less, even more preferably 0.000 or more and 0.500 or less, even more preferably 0.000 or more and 0.400 or less, even more preferably 0.000 or more and 0.350 or less, even more preferably 0.000 or more and 0.300 or less, even more preferably 0.000 or more and 0.250 or less, and even more preferably 0.000 or more and 0.200 or less.

[0120] More specifically, the yellowness of the optical molded body can be measured according to the method described in the examples of the second embodiment.

[0121] The method for producing an optical molded body of the second embodiment preferably includes a step of molding the optical molded body by a method for forming an optical molded body, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, or casting. The method for producing an optical molded body of the second embodiment more preferably includes a step of molding the optical molded body by casting, from the viewpoint of improving the degree of freedom in designing the optical molded body.

[0122] [Photocurable Resin Composition] In the second embodiment, the photocurable resin composition (hereinafter also simply referred to as "resin composition" as appropriate) is a photocurable resin composition that can be used for an optical molded body.

[0123] 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 coloration of the optical molded body.

[0124] The state of the photocurable resin composition is not particularly limited, however, from the viewpoint of suitability for forming an optical molded body by molding using an injection method or a casting method, the photocurable resin composition is preferably in a liquid state.

[0125] 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.

[0126] <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 further reducing the coloration of the optical molded body, the radically polymerizable functional group may be, for example, a (meth)acryloyl group. From the viewpoint of further reducing the coloration of the optical molded body, the polymerizable compound preferably contains a (meth)acrylate monomer (A).

[0127] <(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.

[0128] 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).

[0129] From the viewpoint of improving the crack resistance during molding of the optical molded body and from the viewpoint of further reducing the coloring of the optical molded body, the content of the difunctional or higher (meth)acrylate monomer (A2) in the photocurable resin composition of the second embodiment is preferably 5.0 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 120 parts by mass or less, even more preferably 12 parts by mass or more and 100 parts by mass or less, even more preferably 15 parts by mass or more and 90 parts by mass or less, even more preferably 18 parts by mass or more and 70 parts by mass or less, even more preferably 18 parts by mass or more and 50 parts by mass or less, even more preferably 18 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.

[0130] In the photocurable resin composition of the second 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, from the viewpoint of further reducing coloration of the optical molded body, preferably from 0.50 to 10.0, more preferably from 1.00 to 8.00, even more preferably from 2.00 to 6.00, even more preferably from 3.00 to 5.00, and even more preferably from 3.50 to 4.50.

[0131] <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.

[0132] 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.

[0133] From the viewpoint of further reducing the coloration of the optical molded body, the monofunctional (meth)acrylate monomer (A1) more preferably includes one or more selected from the group consisting of lauryl (meth)acrylate and dicyclopentanyl (meth)acrylate.

[0134] The monofunctional (meth)acrylate monomer (A1) preferably has an alicyclic skeleton, from the viewpoint of further reducing coloration 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 coloration of the optical molded body.

[0135] <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.

[0136] 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.

[0137] 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.

[0138] 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.).

[0139] 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.

[0140] 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.). 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.

[0141] 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.

[0142] 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.

[0143] <Antioxidant (B)> The photocurable resin composition of the second 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] From the viewpoint of further reducing the coloration 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 further reducing the coloration 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).

[0150] The content of the antioxidant (B) in the photocurable resin composition of the second 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), from the viewpoint of further reducing the coloration of the optical molded body.

[0151] 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 mass%, the content of the antioxidant (B) in the photocurable resin composition of the second embodiment is, from the viewpoint of further reducing coloration of the optical molded body, preferably 0.010 mass% or more and 5.0 mass% or less, more preferably 0.050 mass% or more and 4.0 mass% or less, even more preferably 0.10 mass% or more and 3.0 mass% or less, even more preferably 0.50 mass% or more and 2.0 mass% or less, and even more preferably 0.90 mass% or more and 1.0 mass% or less.

[0152] <Photopolymerization initiator (C)> The photocurable resin composition of the second embodiment may further contain a photopolymerization initiator (C). The photopolymerization initiator (C) is not particularly limited, and a known polymerization initiator can be used.

[0153] 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.

[0154] 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.

[0155] From the viewpoint of further reducing coloration 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).

[0156] The content of the photopolymerization initiator (C) in the photocurable resin composition of the second 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, relative to 100 parts by mass of the (meth)acrylate monomer (A), from the viewpoint of improving the curability of the photocurable resin composition. The content of the photopolymerization initiator (C) in the photocurable resin composition of the second 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, relative to 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. The content of the photopolymerization initiator (C) in the photocurable resin composition of the second 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, relative to 100 parts by mass of the (meth)acrylate monomer (A).

[0157] 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 mass%, the content of the photopolymerization initiator (C) in the photocurable resin composition of the second embodiment is preferably 0.10 mass% or more and 10 mass% or less, more preferably 1.0 mass% or more and 8.0 mass% or less, even more preferably 2.0 mass% or more and 6.0 mass% or less, even more preferably 3.0 mass% or more and 5.0 mass% or less, and even more preferably 3.5 mass% or more and 4.0 mass% or less, from the viewpoint of further reducing coloration of the optical molded body.

[0158] <Light Stabilizer (D)> The photocurable resin composition of the second 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 coloring resistance of the photocurable resin composition can be improved.

[0159] The light stabilizer (D) preferably contains a hindered amine-based light stabilizer from the viewpoint of further improving coloration resistance.

[0160] 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.

[0161] 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).

[0162] The content of the light stabilizer (D) in the photocurable resin composition of the second 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 further reducing coloration of the optical molded body. The content of the light stabilizer (D) in the photocurable resin composition of the second 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. 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 mass%, the content of the light stabilizer (D) in the photocurable resin composition of the second embodiment is preferably 0.0010 mass% or more and 1.00 mass% or less, more preferably 0.0050 mass% or more and 0.60 mass% or less, even more preferably 0.010 mass% or more and 0.50 mass% or less, even more preferably 0.050 mass% or more and 0.40 mass% or less, and even more preferably 0.090 mass% or more and 0.30 mass% or less, from the viewpoint of further reducing coloration of the optical molded body and reducing bleed-out.

[0163] <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.

[0164] <Method for producing photocurable resin composition> The photocurable resin composition according to the second 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.

[0165] <Physical Properties of Photocurable Resin Composition> Next, the physical properties of the photocurable resin composition will be described.

[0166] From the viewpoint of improving the heat resistance of the optical molded body, the glass transition temperature Tg of the photocurable resin composition of the second embodiment is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, even more preferably 120°C or higher, even more preferably 125°C or higher, and even more preferably 130°C or higher.

[0167] From the viewpoint of further reducing coloration of the optical molded body, the glass transition temperature Tg of the photocurable resin composition of the second embodiment is preferably 250°C or less, more preferably 230°C or less, even more preferably 210°C or less, even more preferably 190°C or less, even more preferably 170°C or less, even more preferably 150°C or less, and even more preferably 140°C or less.

[0168] From the viewpoint of improving the heat resistance of the optical molded body and further reducing the coloring of the optical molded body, the glass transition temperature Tg of the photocurable resin composition of the second embodiment is preferably 100°C or higher and 250°C or lower, more preferably 110°C or higher and 230°C or lower, even more preferably 115°C or higher and 210°C or lower, even more preferably 120°C or higher and 190°C or lower, even more preferably 125°C or higher and 170°C or lower, even more preferably 130°C or higher and 150°C or lower, and even more preferably 130°C or higher and 140°C or lower.

[0169] More specifically, the glass transition temperature Tg of the photocurable resin composition of the second embodiment can be measured according to the method described in the examples.

[0170] <Uses of Photocurable Resin Composition> Next, uses of the photocurable resin composition will be described.

[0171] The photocurable resin composition of the second embodiment can reduce coloration 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 methods. In particular, the photocurable resin composition of the second embodiment can be used in casting methods.

[0172] The photocurable resin composition of the second embodiment can reduce coloration 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.

[0173] The photocurable resin composition of the second embodiment can be preferably used for, for example, a lens, which may include, 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.

[0174] The photocurable resin composition of the second 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).

[0175] The photocurable resin composition of the second 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.

[0176] The photocurable resin composition of the second 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).

[0177] [Optical Molded Body] The optical molded body of the second embodiment includes a cured product of the photocurable resin composition of the second embodiment. The optical molded body of the second embodiment can be manufactured using the photocurable resin composition of the second embodiment. The optical molded body can be manufactured from the photocurable resin composition of the second embodiment by any method, such as injection molding, compression molding, injection compression molding, extrusion molding, solution casting, or casting.

[0178] The optical molded body of the second 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.

[0179] The lens of the second 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).

[0180] The optical molded body of the second 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.

[0181] The cover display of the second embodiment includes one or more types selected from the group consisting of a cover display for a virtual reality device (cover display for a VR device), a cover display for a mixed reality device (cover display for an MR device), a cover display for an augmented reality device (cover display for an AR device), a cover display for a cross reality device (cover display for an xR device), and a cover display for a head-mounted display (cover display for an HMD).

[0182] 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.

[0183] For example, the optical molded body of the second 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.

[0184] For example, the optical molded body of the second 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.

[0185] For example, the optical molded body of the second 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.

[0186] The photocurable resin composition of the second embodiment can reduce coloring of the optical molded body, and therefore can be applied to optical molded bodies having a thickness of 1.0 mm or more.

[0187] (Optical Device) The optical device of the second embodiment includes the optical molded body of the second embodiment. The type of the optical device of the second embodiment is not particularly limited. Examples of the optical device of the second 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).

[0188] While the second embodiment of the present invention has been described above, this is merely an example of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the second embodiment, and modifications and improvements that do not impair the effects of the present invention are included in the present invention.

[0189] While 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 within the scope of achieving the object of the present invention are included in the present invention.

[0190] Additionally, the present invention also includes configurations that combine the configurations of the above-described embodiments.

[0191] Hereinafter, each embodiment of the present invention will be described in detail with reference to examples, etc. However, each embodiment of the present invention is not limited to the description of these examples.

[0192] <<Examples 1A to 3A and Reference Example 1A>> The first embodiment of the present invention will be described in detail below with reference to Examples 1A to 3A and Reference Example 1 A. Note that the first embodiment is not limited to the descriptions of these examples.

[0193] First, the materials used in Examples 1A to 3A and Reference Example 1A are listed below. Polymerizable compound: (meth)acrylate monomer (A) Monofunctional (meth)acrylate monomer (A1)1: LA (lauryl acrylate, manufactured by Osaka Organic Chemical Industry Ltd.) Monofunctional (meth)acrylate monomer (A1)2: GM81HDA (dicyclopentanyl methacrylate, manufactured by Kunisei Chemical Industry Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2)1: DCP (tricyclodecane dimethanol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2)2: DDD (1,12-dodecanediol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Antioxidant (B) Antioxidant 1: thioether-based antioxidant (2,2-bis[[3-(dodecylthio)propionic acid]3-oxopropyloxy]methyl]-1,3-propanediyl, manufactured by ADEKA Corporation, product name: Adeka STAB 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: Adeka STAB 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)

[0194] (Examples 1A to 3A, Reference Example 1A) 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.

[0195] [Residual organic radical rate R when heated at 120°C for 10 minutes １０ Measurement of the organic radical remaining rate R for each photocurable resin composition according to the following <Method for calculating organic radical remaining rate (120°C, 10 minutes)>. １０ were calculated respectively.

[0196] <Method for calculating the residual organic radical ratio (120°C, 10 minutes)> The amount of organic radicals measured in accordance with the <Initial organic radical amount measurement> below for a first cured film produced using a photocurable resin composition according to the <Cured film production conditions> below was used to calculate the residual organic radical ratio A. ０ The amount of organic radicals of the first cured film measured according to the following <Measurement of organic radical amount after heating (120°C, 10 minutes)> was defined as organic radical amount A. １ Amount of organic radicals A ０ and the amount of organic radicals A １ Using the above, the organic radical remaining rate R is calculated by the following formula (10). １０ (10): Organic radical remaining rate R １０ (%) = 100 x A １ / A ０

[0197] <Conditions for Producing Cured Films> 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 a 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 of it. 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, filling the circular hole in the silicone sheet with a photocurable resin, and then further placing alkali-free glass on top of that may be referred to as a laminate. The above-mentioned laminate was placed on a SUS lab jack, and the height of the SUS lab jack was adjusted. The photocurable resin composition was irradiated from above the alkali-free glass with LED light having a wavelength of 405 nm at 810 mW for 3 minutes 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 laminate was then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for an additional 3 minutes. After irradiation 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.).

[0198] <Measurement of initial organic radical amount> Within 1 hour to 2 hours after the completion of LED light irradiation, the first cured film was placed in a polyethylene bag and broken using a wooden mallet to obtain fragments of the first cured film. 7 mg of a first sample to be used for measuring the amount of organic radicals was collected from the fragments of the first cured film. One hour after collecting the first sample, the amount of organic radicals A at a measurement temperature of 23°C was measured by electron spin resonance (ESR) using the first sample according to the following <ESR measurement conditions>. ０ was measured.

[0199] <Measurement of organic radical amount after heating (120°C, 10 minutes)> After the above <Initial organic radical amount measurement> was completed, the temperature of the electron spin resonance apparatus described below was raised to 120°C over 10 minutes while the first sample was held inside the apparatus, and the first sample was heated at 120°C for 10 minutes. After the first sample was heated, the organic radical amount A at a measurement temperature of 120°C was measured by electron spin resonance (ESR) using the first sample according to the following <ESR measurement conditions>. １ was measured.

[0200] <ESR measurement conditions> Apparatus: Electron spin resonance apparatus (manufactured by JEOL Ltd., product name: JES-TE200) Resonance frequency: 9.2 GHz Microwave input: 1 mW Central magnetic field: 327.0 mT Sweep width: ±15 mT Modulation frequency: 100 kHz (modulation width: 1.0 mT) Sweep time: 2 minutes Time constant: 0.03 seconds Sample tube: X-band compatible sample tube with quartz tip External standard: Mn supported on magnesium oxide ２＋ Standard sample External standard memory: 850.0 Measurement temperature: 23°C and 120°C Measurement atmosphere: Air Sample: 7 mg

[0201] In the above formula (10), the amount of organic radicals A ０ is the normalized organic radical amount A shown in the following formula (11): ０Ｓ In addition, in the above formula (10), the amount of organic radicals A １ is the normalized amount of organic radicals A shown in the following formula (12): １Ｓ (11): Normalized organic radical amount A ０Ｓ = (area of ​​the part of the ESR spectrum corresponding to the organic radical in <Measurement of the amount of initial organic radical>) / {(Mn of the ESR spectrum in <Measurement of the amount of initial organic radical>)} ２＋ (12): Normalized amount of organic radicals A １Ｓ = (area of ​​the part corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 10 minutes)>) / {(Mn ２＋(area of ​​the portion (second signal) corresponding to (1) × (sampling amount of the first sample))

[0202] The baseline of the ESR spectrum is Mn ２＋ (second signal) was used as a reference for correction. Usually, in the relative comparison of radical amounts, the reference Mn ２＋ The area of ​​the derived signal is Mn ２＋ However, the spectrum of the radical derived from the organic radical and Mn ２＋ (third signal) overlaps with Mn ２＋ (second signal) was used (external standard memory = 850.0). In addition, the signal derived from the organic radical was Mn ２＋ When the signal overlapped with the third signal, the ESR spectrum with an external standard memory of 0 was used for calculation.

[0203] [Residual organic radical rate R when heated at 120°C for 30 minutes ３０ Measurement of the organic radical remaining rate R for each photocurable resin composition according to the following <Method for calculating organic radical remaining rate (120°C, 30 minutes)>. ３０ were calculated respectively.

[0204] <Method for calculating the residual organic radical ratio (120°C, 30 minutes)> The amount of organic radicals measured in accordance with the following <Measurement of initial organic radical amount (second cured film)> for a second cured film produced using a photocurable resin composition according to the above <Conditions for producing a cured film> was determined as organic radical amount A. ２ The amount of organic radicals of the second cured film measured according to the following <Measurement of organic radical amount after heating (120°C, 30 minutes)> was defined as organic radical amount A. ３ Amount of organic radicals A ２ and the amount of organic radicals A ３ Using the above, the organic radical remaining rate R is calculated by the following formula (13): ３０ (13): Organic radical remaining rate R ３０ (%) = 100 x A ３ / A ２

[0205] <Measurement of initial organic radical amount (second cured film)> Within 2 hours after the completion of LED light irradiation, the second cured film was placed in a polyethylene bag and broken using a wooden mallet to obtain fragments of the second cured film. 7 mg of a second sample to be used for measuring the amount of organic radicals was collected from the fragments of the second cured film. One hour after collecting the second sample, the amount of organic radicals A at a measurement temperature of 23°C was measured by electron spin resonance (ESR) using the second sample according to the above <ESR measurement conditions>. ２ was measured.

[0206] <Measurement of organic radical amount after heating (120°C, 30 minutes)> After the above <Measurement of initial organic radical amount (second cured film)> was completed, the temperature of the electron spin resonance apparatus was raised to 120°C over 10 minutes while the second sample was held inside the electron spin resonance apparatus, and the second sample was heated at 120°C for 30 minutes. After heating the second sample, the organic radical amount A at a measurement temperature of 120°C was measured by electron spin resonance (ESR) using the second sample according to the following <ESR measurement conditions>. ３ was measured.

[0207] In the above formula (13), the amount of organic radicals A ２ is the normalized organic radical amount A shown in the following formula (14): ２Ｓ In addition, in the above formula (13), the amount of organic radicals A ３ is the normalized organic radical amount A shown in the following formula (15): ３Ｓ (14): Normalized organic radical amount A ２Ｓ = (area of ​​the portion corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of initial organic radicals (second cured film)>) / {(Mn ２＋ (15): Normalized amount of organic radicals A ３Ｓ = (area of ​​the part corresponding to the organic radical in the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 30 minutes)>) / {(Mn of the ESR spectrum of <Measurement of the amount of organic radical after heating (120°C, 30 minutes)>)} ２＋(area of ​​the portion (second signal) corresponding to (2) × (sampling amount of the second sample))

[0208] [Measurement of YI Value] The cured film of each example was heated at 120°C for 10 minutes or 30 minutes, and then the yellowness index (YI value) was measured according to ASTM E313-73 under the conditions shown below in "Measurement Conditions for YI Value."

[0209] <Conditions for measuring YI value> Measuring device: Spectroscopic colorimeter / haze meter (product name: COH-7700, manufactured by Nippon Denshoku Industries Co., Ltd.) Film thickness: 3 mm Film diameter: 35 mmφ

[0210] The YI value when the cured film was heated at 120°C for 10 minutes was １０ The YI value when the cured film was heated at 120°C for 30 minutes was ３０ are called respectively.

[0211]

[0212] <<Examples 1B to 8B and Comparative Examples 1B to 2B>> The second embodiment of the present invention will be described in detail below with reference to Examples 1B to 8B and Comparative Examples 1B to 2B. Note that the second embodiment is not limited to the descriptions of these examples.

[0213] First, the materials used in each example are listed. Polymerizable compound: (meth)acrylate monomer (A) Monofunctional (meth)acrylate monomer (A1): GM81HDA (dicyclopentanyl methacrylate, manufactured by Kunisei Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2) 1: DCP (tricyclodecane dimethanol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Difunctional or higher functional (meth)acrylate monomer (A2) 2: DDD (1,12-dodecanediol dimethacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) Antioxidant (B) Antioxidant 1: thioether-based antioxidant (bis[3-(dodecylthio)propionic acid]2,2-bis[[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: phenolic antioxidant (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA Corporation, product name: Adeka STAB 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: Adeka STAB LA-82) (hereinafter also referred to as LA-82)

[0214] (Production Examples 1B to 2B) Liquid photocurable resin compositions were obtained by blending the components to obtain the formulations shown in Table 2. The formulations in Table 2 are expressed in parts by mass. The physical properties of the photocurable resin compositions obtained in each production example were measured by the following methods. The measurement results are shown in Table 2.

[0215] <Measurement of Glass Transition Temperature Tg> Using the photocurable resin composition of each Production Example, a cured film was produced according to the following <Cured Film Production Conditions>. Using the cured film of each Production Example, the glass transition temperature Tg of the photocurable resin composition was measured according to the following <Method for Measuring Glass Transition Temperature Tg>.

[0216] <Conditions for producing a cured film> A 100 μm thick, 100 mm × 100 mm PET film (without release treatment, manufactured by Teijin Limited, product name: Melinax S) was placed on a 2.0 mm thick, 100 mm × 100 mm alkali-free glass (product name: JIS R 3202, glass plate thread surface, manufactured by Test Piece Co., Ltd.), and a 100 μm thick, 100 mm × 100 mm PTFE sheet (material: PTFE, manufactured by Chukoh Chemical Industry Co., Ltd.) with a 70 mm diameter circular hole drilled therein was placed on top of the PET film. After filling the circular hole in the PTFE 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) was placed on top of it, and then 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.) was placed on top. At this time, it was confirmed that there were no air bubbles, and the glass was fixed with clips at eight locations to ensure a uniform thickness. Hereinafter, the PET film and PTFE sheet were placed on the alkali-free glass, the circular hole in the PTFE sheet was filled with a photocurable resin, and then the PET film and alkali-free glass were placed on top of that. This may be referred to as a laminate. The above-mentioned laminate was placed on a SUS lab jack, and the height of the SUS lab jack was adjusted. The photocurable resin composition was irradiated from above the alkali-free glass with LED light having a wavelength of 405 nm at 810 mW for 5 minutes 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 laminate was then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for an additional 5 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, PET film, and PTFE sheet, and further heated at 120°C for 1 hour to obtain a cured film of the photocurable resin composition.

[0217] <Method for Measuring Glass Transition Temperature Tg> The cured film of each Production Example was cut into a size of 10 mm wide x 45 mm long, and the cured product was prepared as a test specimen, with thicknesses of 90 to 110 μm at four points every 10 mm in the lengthwise direction. Next, dynamic viscoelasticity measurement (DMA) was performed using the obtained test specimen. The measurement conditions were as shown in the <DMA Measurement Conditions> below. The test specimens of each Production Example were measured in accordance with JIS K7244-4:1999. Specifically, dynamic viscoelasticity measurement was performed using a dynamic viscoelasticity measuring device to measure the storage modulus E' and loss modulus E''. Next, the loss tangent tanδ was calculated using the following formula (16): (16): Loss tangent tanδ = loss modulus E'' / storage modulus E' Finally, the temperature at which the loss tangent tanδ was maximized was determined as the glass transition temperature Tg.

[0218] <DMA measurement conditions> Measuring device: Dynamic viscoelasticity measuring device (product name: DMS6100, manufactured by Seiko Instruments Inc.) Frequency: 1 Hz Heating rate: 5°C / min Strain: 0.1% Measurement mode: Tensile mode Distance between chucks: 20 mm Sample width: 10 mm Measurement atmosphere: Air

[0219] (Examples 1B to 4B, Comparative Example 1B) The photocurable resin composition of Production Example 1B was used to carry out the production methods of Examples 1B to 4B and Comparative Example 1B. In the production methods of Examples 1B to 4B and Comparative Example 1B, the curing step and / or heating step was carried out so as to achieve the production method details shown in Table 2. An optical molded body was obtained in each example by the production methods of Examples 1B to 4B and Comparative Example 1B. Note that Comparative Example 1B is an example in which the heating step was not carried out.

[0220] <Curing Step> 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 a 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, filling the circular hole in the silicone sheet with a photocurable resin, and then further placing alkali-free glass on top of that may be referred to as a laminate. The obtained laminate was placed on a SUS lab jack, and the height of the SUS lab jack was adjusted. The photocurable resin composition was irradiated from above the alkali-free glass with LED light having a wavelength of 405 nm at 810 mW for 3 minutes 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 laminate was then turned over and irradiated with LED light having a wavelength of 405 nm at 810 mW for an additional 3 minutes. After irradiation 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, and an optical molded body was obtained in each example.

[0221] <Heating Step> The optical molded body obtained in each example was heated under the heating temperature and heating time conditions shown in Table 2, thereby carrying out the heating step for each example. A heating dryer was used for the heating step. Heating of the optical molded body for each example was started within 180 minutes after the optical molded body for each example was produced. The optical molded body of Example 1B was placed in a heating dryer at 120°C. 10 minutes after the optical molded body of Example 1B was placed in the heating dryer, the optical molded body of Example 1B was removed from the heating dryer. Thereafter, the optical molded body of Example 1B was allowed to cool at 23°C for 30 minutes. The optical molded body of Example 2B was placed in a heating dryer at 120°C. 30 minutes after the optical molded body of Example 2B was placed in the heating dryer, the optical molded body of Example 2B was removed from the heating dryer. Thereafter, the optical molded body of Example 2B was allowed to cool at 23°C for 30 minutes. The optical molded body of Example 3B was placed in a heated dryer at 120°C. 60 minutes after the optical molded body of Example 3B was placed in the heated dryer, the optical molded body of Example 3B was removed from the heated dryer. Thereafter, the optical molded body of Example 3B was allowed to cool at 23°C for 30 minutes. The optical molded body of Example 4B was placed in a heated dryer at 140°C. 60 minutes after the optical molded body of Example 4B was placed in the heated dryer, the optical molded body of Example 4B was removed from the heated dryer. Thereafter, the optical molded body of Example 4B was allowed to cool at 23°C for 30 minutes.

[0222] (Examples 5B to 8B, Comparative Example 2B) The photocurable resin composition of Production Example 2B was used to carry out the production methods of Examples 5B to 8B and Comparative Example 2B. In the production methods of Examples 5B to 8B and Comparative Example 2B, the curing step and / or heating step was carried out so as to achieve the production method details shown in Table 2. An optical molded body was obtained in each example by the production methods of Examples 5B to 8B and Comparative Example 2B. Note that Comparative Example 2B is an example in which the heating step was not carried out.

[0223] The details of the curing step and the heating step in the manufacturing methods of Examples 5B to 8B and Comparative Example 2B were the same as the details of the <Curing step> and <Heating step> described above.

[0224] [Measurement of Yellowness Index (YI Value)] The yellowness index (YI value) of the optical molded body obtained in each example was measured in accordance with ASTM E313-73 for optical molded bodies. The yellowness index YI value before the heating step for the optical molded body obtained in each example was １ and the yellowness index YI after the heating process ２ The conditions for measuring the yellowness index (YI value) were as shown in <Conditions for measuring the yellowness index (YI value)> below.

[0225] <Conditions for measuring yellowness index (YI value)> Measuring device: Spectroscopic colorimeter / haze meter (product name: COH-7700, manufactured by Nippon Denshoku Industries Co., Ltd.) Thickness of test piece: 3 mm Diameter of test piece: 35 mmφ The test pieces were prepared using the optical molded bodies obtained in each example.

[0226] Yellowness index YI after heating of the optical molded body obtained in each example ２ After measuring, the yellowness index YI before heating was calculated according to the following formula (17): １ Yellowness index YI after heating ２ The ratio of (17):YI was calculated. １ YI for ２ Ratio of YI ２ / YI １

[0227]

[0228] It can be seen from Table 2 that the manufacturing methods of the Examples (Examples 1B to 8B) were able to reduce the coloring of the optical molded body compared to the manufacturing methods of the Comparative Examples (Comparative Examples 1B to 2B). That is, the manufacturing method of the optical molded body of the second embodiment can reduce the coloring of the optical molded body. In addition, it can be seen from Table 1 that the photocurable resin compositions of the Examples (Examples 1A to 3A) were able to further reduce the coloring of the optical molded body compared to the photocurable resin composition of the Reference Example (Reference Example 1A). That is, the photocurable resin composition of the first embodiment can further reduce the coloring of the optical molded body.

[0229] This application claims priority based on Japanese Patent Application Nos. 2024-012839 and 2024-012880, filed on January 31, 2024, and Japanese Patent Application No. 2024-069282, filed on April 22, 2024, the disclosures of which are incorporated herein in their entirety.

Claims

1. A photocurable resin composition that can be used for an optical molded body, wherein the organic radical residual rate of the photocurable resin composition is 20.0% or less, as calculated according to the following <Method for calculating organic radical residual rate>. <Method for calculating organic radical residual rate> The organic radical amount A of a first cured film produced using the photocurable resin composition according to the following <Conditions for producing a cured film> is measured according to the following <Measurement of initial organic radical amount>. ０ and an organic radical amount A of the first cured film measured according to the <Measurement of organic radical amount after heating> described below. １ Using the above, the organic radical remaining rate is calculated by the following formula (1): (1): Organic radical remaining rate (%) = 100 × A １ / A ０ <Conditions for Producing 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. 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. <Measurement of initial organic radical amount> Within 1 hour to 2 hours after the completion of LED light irradiation, 7 mg of a first sample was collected from the first cured film, and 1 hour after the first sample was collected, the amount of organic radicals A at a measurement temperature of 23°C was measured by electron spin resonance (ESR) using the first sample according to the following <ESR measurement conditions>. ０ <Measurement of organic radical amount after heating> After the <Measurement of initial organic radical amount> is completed, the temperature of the electron spin resonance apparatus is increased to 120°C over 10 minutes while the first sample is held inside the electron spin resonance apparatus described below, and the first sample is heated at 120°C for 10 minutes. After the heating of the first sample, the amount of organic radicals A at a measurement temperature of 120°C is measured by electron spin resonance (ESR) using the first sample according to the <ESR measurement conditions> described below. １ <ESR measurement conditions> Apparatus: electron spin resonance apparatus Resonance frequency: 9.2 GHz Microwave input: 1 mW Central magnetic field: 327.0 mT Sweep width: ±15 mT Modulation frequency: 100 kHz (modulation width: 1.0 mT) Sweep time: 2 minutes Time constant: 0.03 seconds Sample tube: X-band compatible sample tube with quartz tip External standard: Mn supported on magnesium oxide ２＋ Standard sample External standard memory: 850.0 Measurement temperature: 23°C and 120°C Measurement atmosphere: Air Sample: 7 mg 2. In the above <Measurement of the amount of organic radicals after heating>, １ is the normalized amount of organic radicals A calculated by the following formula (2): １Ｓ wherein the normalized organic radical amount A １Ｓ The photocurable resin composition according to claim 1, wherein (2): normalized organic radical amount A is 50.0 or less. １ = (area of the part of the ESR spectrum corresponding to the organic radical) / {(Mn ２＋ (area of the portion (second signal) corresponding to the first sample) × (sampling amount of the first sample)} 3. The photocurable resin composition according to claim 1 or 2, which contains one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and di- or higher functional (meth)acrylate monomers.

4. A photocurable resin composition according to claim 3, wherein the content of the difunctional or higher (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 (meth)acrylate monomer is 100 parts by mass.

5. A photocurable resin composition according to claim 3 or 4, wherein the mass ratio of the content of the monofunctional (meth)acrylate monomer to the content of the difunctional or higher functional (meth)acrylate monomer is 0.50 or more and 10.0 or less.

6. The photocurable resin composition according to any one of claims 3 to 5, wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton.

7. The photocurable resin composition according to any one of claims 3 to 6, wherein the di- or higher functional (meth)acrylate monomer has an alicyclic skeleton.

8. The photocurable resin composition according to any one of claims 3 to 7, wherein the di- or higher functional (meth)acrylate monomer has a linear hydrocarbon skeleton.

9. The photocurable resin composition according to any one of claims 1 to 8, wherein a cured film prepared using the photocurable resin composition according to the <Cured Film Preparation Conditions> is heated at 120°C for 10 minutes, and the yellowness index (YI value) measured in accordance with ASTM E313-73 is 8.50 or less.

10. The photocurable resin composition according to any one of claims 1 to 9, further comprising an antioxidant.

11. The photocurable resin composition according to any one of claims 1 to 10, further comprising a photopolymerization initiator.

12. The photocurable resin composition according to claim 11, wherein the photopolymerization initiator comprises a photoradical polymerization initiator.

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

14. A photocurable resin composition according to any one of claims 1 to 13, which can be used in a casting method.

15. The photocurable resin composition according to any one of claims 1 to 14, 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).

16. An optical molded body comprising a cured product of the photocurable resin composition according to any one of claims 1 to 15.

17. The optical molded body of claim 16, wherein the optical molded body comprises a lens.

18. The optical molded body according to claim 17, 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).

19. The optical molded body of claim 16, wherein the optical molded body comprises a cover display.

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

21. The optical molded body according to any one of claims 16 to 20, wherein the maximum thickness is 20 mm or less.

22. The optical molded body according to any one of claims 16 to 21, wherein the maximum thickness is 1.0 mm or more.

23. A method for producing an optical molded body, comprising: a curing step of producing an optical molded body by irradiating a photocurable resin composition with light to cure it; and a heating step of reducing coloration of the optical molded body by heating the optical molded body.

24. The method for producing an optical molded body according to claim 23, wherein the photocurable resin composition has a glass transition temperature of 100°C or higher.

25. The method for producing an optical molded body according to claim 23 or 24, wherein the heating temperature for heating the optical molded body in the heating step is 80°C or higher.

26. A method for producing an optical molded body according to any one of claims 23 to 25, wherein in the heating step, the temperature at which the optical molded body is heated is less than the glass transition temperature of the photocurable resin composition plus 20°C.

27. A method for producing an optical molded body according to any one of claims 23 to 26, wherein the heating time for heating the optical molded body in the heating step is 1 minute or longer.

28. Yellowness index YI of the optical molded body before the heating step measured in accordance with ASTM E313-73 １ Yellowness index YI measured according to ASTM E313-73 of the optical molded body after the heating step ２ The ratio of YI ２ / YI １ The method for producing an optical molded body according to any one of claims 23 to 27, wherein is 0.900 or less.

29. A method for producing an optical molded body according to any one of claims 23 to 28, comprising the step of molding the optical molded body by a casting method.

30. A method for producing an optical molded body according to any one of claims 23 to 29, wherein the photocurable resin composition contains one or more monomers selected from the group consisting of monofunctional (meth)acrylate monomers and di- or higher functional (meth)acrylate monomers.

31. A method for producing an optical molded body as described in claim 30, wherein the content of the difunctional or higher (meth)acrylate monomer in the photocurable resin composition is 5.0 parts by mass or more and 150 parts by mass or less, when the total content of the monofunctional (meth)acrylate monomer and the difunctional or higher (meth)acrylate monomer is 100 parts by mass.

32. A method for producing an optical molded body according to claim 30 or 31, wherein the photocurable resin composition has a mass ratio of the content of the monofunctional (meth)acrylate monomer to the content of the difunctional or higher functional (meth)acrylate monomer of 0.50 or more and 10.0 or less.

33. The method for producing an optical molded body according to any one of claims 30 to 32, wherein the monofunctional (meth)acrylate monomer has an alicyclic skeleton.

34. The method for producing an optical molded body according to any one of claims 30 to 33, wherein the di- or higher functional (meth)acrylate monomer has an alicyclic skeleton.

35. The method for producing an optical molded body according to any one of claims 30 to 34, wherein the di- or higher functional (meth)acrylate monomer has a linear hydrocarbon skeleton.

36. The method for producing an optical molded body according to any one of claims 23 to 35, wherein the photocurable resin composition further contains a photopolymerization initiator.

37. The method for producing an optical molded body according to claim 36, wherein the photopolymerization initiator includes a photoradical polymerization initiator.

38. A method for producing an optical molded body according to any one of claims 23 to 36, wherein the optical molded body includes a lens.

39. A method for producing an optical molded body according to claim 38, 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).

40. A method for producing an optical molded body according to any one of claims 23 to 39, wherein the maximum thickness of the optical molded body is 20 mm or less.

41. A method for producing an optical molded body according to any one of claims 23 to 40, wherein the maximum thickness of the optical molded body is 1.0 mm or more.

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