Photocurable resin composition, optical member, and method for producing three-dimensional object

Abstract

The present invention addresses the problem of providing a photocurable resin composition which can be used for the creation of an object by using, for example, an inkjet device for 3D stereolithography, and which can provide a cured object having high surface smoothness. A photocurable resin composition that solves the problem comprises (A) an epoxy compound, (B) an oxetane compound, and (C) a photoacid generator, wherein the epoxy compound (A) comprises (a1) an alicyclic epoxy compound and / or (a2) a monofunctional epoxy compound having a biphenyl structure, the viscosity of the photocurable resin composition as measured using an E-type viscometer under conditions of 25°C and 20 rpm is 50 m·Pa s or less, and the refractive index of light having a wavelength of 589 nm in a cured article produced by curing the photocurable resin composition using an UV-LED having a wavelength of 395 nm at a illuminance of 1000 mW / cm2 and a cumulative light intensity of 1500 mJ / cm2 is 1.50 or more.

Description

Photocurable resin composition, optical member, and method for producing three-dimensional object

[0001] The present invention relates to a photocurable resin composition, an optical member, and a method for producing a three-dimensional object.

[0002] Conventionally, various optical lenses have been developed, and these are manufactured by molding resin into a desired shape. In recent years, eyeglass-type wearable devices such as AR (Augmented Reality) glasses have been developed. Lenses for such eyeglass-type wearable devices are generally manufactured by, for example, injection molding using a mold. Injection molding has the advantage of enabling mass production using a mold.

[0003] However, there is a demand for lenses that can be tailored to individual needs and that can be produced at lower cost. To address this, for example, the production of lenses by three-dimensional optical lithography or the like has been considered. This method reduces the waste of material and does not require a mold, making it possible to produce lenses at lower cost than conventional methods.

[0004] Various resin compositions have been proposed for use in three-dimensional optical shaping, including a photocurable resin composition containing hydroxyethyl methacrylate or the like (Patent Document 1) and an actinic energy ray-curable resin composition containing a (meth)acryloyl polymer (Patent Document 2).

[0005] JP 2020-501953 A JP 2010-60890 A

[0006] Resin compositions for producing optical components such as the above-mentioned lenses are required to have high optical transmittance, a high refractive index, and the ability to be precisely shaped. Among the various 3D stereolithography methods, a method using an inkjet printer for 3D stereolithography is known as a method capable of precisely shaping. In contrast, the resin composition disclosed in Patent Document 1 has a low refractive index of the cured product, making it unsuitable for producing optical components. Furthermore, the resin composition disclosed in Patent Document 2 has a high viscosity, making it difficult to eject from an inkjet printer for 3D stereolithography. Even if the resin composition could be ejected from the printer, photocuring it was prone to oxygen inhibition and curing shrinkage. Therefore, there were issues such as insufficient curing of the resulting cured product and poor surface smoothness of the cured product. Furthermore, other known resin compositions for inkjet printers for 3D stereolithography also often had issues in terms of curability and surface smoothness of the cured product.

[0007] The present invention has been made in view of the above-mentioned problems. An object of the present invention is to provide a photocurable resin composition that can be used for modeling using an inkjet device for three-dimensional modeling and that produces a cured product with high surface smoothness. Another object of the present invention is to provide an optical element obtained from the photocurable resin composition, as well as a method for producing a three-dimensionally modeled object.

[0008] The present invention provides the following photocurable resin composition: [1] A photocurable resin composition comprising: (A) an epoxy compound, (B) an oxetane compound, and (C) a photoacid generator, wherein the epoxy compound (A) is (a1) an alicyclic epoxy compound and / or (a2) a monofunctional epoxy compound having at least one aromatic ring, and has a viscosity of 50 mPa s or less as measured at 25°C and 20 rpm using an E-type viscometer, and an irradiance of 1000 mW / cm irradiated with a UV-LED having a wavelength of 395 nm. ２ , cumulative light intensity 1500 mJ / cm ２A photocurable resin composition, wherein the cured product obtained by curing with the above-mentioned method has a refractive index of 1.50 or higher at light with a wavelength of 589 nm. [2] The photocurable resin composition according to [1], wherein the amount of the (A) epoxy compound is 10% by mass or more and 60% by mass or less. [3] The photocurable resin composition according to [1] or [2], wherein the (a1) alicyclic epoxy compound is a compound containing a cycloalkene oxide structure. [4] The photocurable resin composition according to any of [1] to [3], wherein the molecular weight of the (B) oxetane compound is 180 or more. [5] The photocurable resin composition according to any of [1] to [4], wherein the amount of the (B) oxetane compound is 40% by mass or more and 90% by mass or less.

[0009] The present invention provides the following optical member. [6] An optical member comprising a cured product of the photocurable resin composition according to any one of [1] to [5] above. [7] An optical member which is a laminate of layered cured products of a photocurable resin composition comprising at least (A) an epoxy compound and (B) an oxetane compound, wherein the refractive index of the optical member at a wavelength of 589 nm is 1.50 or more and the surface of the optical member is smooth. The present invention also provides the following method for producing a three-dimensionally shaped object. [8] A method for producing a three-dimensionally shaped object, comprising: a discharging step of discharging a resin composition in layers from an inkjet nozzle; and a layered cured product preparation step of irradiating the resin composition with light having a wavelength of 350 to 450 nm to prepare a layered cured product, the method comprising repeating the discharging step and the layered cured product preparation step, wherein the resin composition comprises at least (A) the epoxy compound and (B) the oxetane compound, and the three-dimensionally shaped object has a refractive index of 1.50 or more at a wavelength of 589 nm.

[0010] The photocurable resin composition of the present invention can be used for modeling using an inkjet device for three-dimensional modeling, etc. The photocurable resin composition can provide a cured product with high surface smoothness.

[0011] The photocurable resin composition of the present invention, a method for producing a three-dimensional object using the same, and an optical member obtained therefrom will be described below. However, the photocurable resin composition and optical member of the present invention are not limited to those described below.

[0012] 1. Photocurable Resin Composition The photocurable resin composition of the present invention (hereinafter also referred to simply as "resin composition") is a composition that is photocurable and can be used in three-dimensional modeling techniques. In this specification, "photocurable" refers to curing by irradiation with ultraviolet light, visible light, infrared light, electron beams, X-rays, alpha rays, beta rays, gamma rays, or the like. The resin composition of the present invention is preferably cured by irradiation with ultraviolet light or visible light. Furthermore, the resin composition of the present invention can be applied to any three-dimensional modeling method using a liquid, but is preferably used for modeling using an inkjet device for three-dimensional modeling. Hereinafter, a case where the resin composition is used for modeling using an inkjet device for three-dimensional modeling (hereinafter also referred to as "inkjet device") will be described as an example, but the three-dimensional modeling method is not limited thereto.

[0013] The resin composition of the present invention comprises (A) an epoxy compound, (B) an oxetane compound, and (C) a photoacid generator. The (A) epoxy compound is either (a1) an alicyclic epoxy compound or (a2) a monofunctional epoxy compound having a biphenyl structure, or both. The resin composition has a viscosity of 50 mPa·s or less as measured at 25°C and 20 rpm using an E-type viscometer. Furthermore, the resin composition is irradiated with a UV-LED having a wavelength of 395 nm at an illuminance of 1000 mW / cm. ２ , cumulative light intensity 1500 mJ / cm ２ The refractive index (nD) of the cured product at a wavelength of 589 nm (D line) is 1.50 or more.

[0014] In the present invention, the resin composition has a predetermined viscosity, allowing it to be stably ejected from an inkjet device. Furthermore, the resin composition contains (A) a specific epoxy compound, (B) an oxetane compound, and (C) a photoacid generator. Therefore, the resin composition is less susceptible to oxygen inhibition during curing and can be efficiently cured in the atmosphere (in the presence of oxygen). Furthermore, the inclusion of these components in the resin composition reduces volume change (shrinkage) during curing. Therefore, three-dimensional modeling can be performed with high precision. Furthermore, because the viscosity of the resin composition is within a moderate range, droplets of the resin composition ejected from the inkjet device can wet and spread appropriately upon impact. This combined effect enhances the surface smoothness of the resulting cured product. Furthermore, because the refractive index (nD) of the cured product of the resin composition is 1.50 or higher, the resulting cured product can be used in applications requiring a high refractive index, such as optical components such as lenses. Each component constituting the resin composition is described in detail below.

[0015] (A) Epoxy Compound The (A) epoxy compound is composed of either or both of an (a1) alicyclic epoxy compound and an (a2) monofunctional epoxy compound having at least one aromatic ring (hereinafter also referred to as "(a2) monofunctional epoxy compound"). When a resin composition contains such an (A) epoxy compound, it becomes possible to efficiently cure in the atmosphere (in the presence of oxygen). Furthermore, the refractive index of the cured resin composition is also increased. The (A) epoxy compound may contain only one type of (a1) alicyclic epoxy compound, or may contain two or more types. The (A) epoxy compound may also contain only one type of (a2) monofunctional epoxy compound, or may contain two or more types.

[0016] The amount of (A) epoxy compound in the resin composition (the total amount when multiple types are included) is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less. When the amount of (A) epoxy compound is 10% by mass or more, the refractive index of the cured product of the resin composition is more likely to fall within the desired range. On the other hand, when the amount of (A) epoxy compound is 60% by mass or less, the amount of (B) oxetane compound etc. becomes relatively sufficient, and the viscosity of the resin composition is more likely to fall within the desired range.

[0017] (a1) Alicyclic Epoxy Compound The (a1) alicyclic epoxy compound is not particularly limited as long as it is a compound having one or more alicyclic hydrocarbon structures and one or more epoxy groups in the molecule. The (a1) alicyclic epoxy compound is preferably a liquid compound at 25°C, and its viscosity, measured using an E-type viscometer at 25°C and 20 rpm, is preferably 10 mPa·s or more and 500 mPa·s or less, more preferably 30 mPa·s or more and 300 mPa·s or less. When the viscosity of the (a1) alicyclic epoxy compound is within this range, the viscosity of the resin composition is more likely to fall within the above-mentioned range.

[0018] The molecular weight or weight-average molecular weight of the (a1) alicyclic epoxy compound is preferably 100 or more and 800 or less, more preferably 120 or more and 500 or less, and even more preferably 140 or more and 400 or less. The weight-average molecular weight is a value (polystyrene equivalent) measured by gel permeation chromatography (GPC). When the molecular weight or weight-average molecular weight of the (a1) alicyclic epoxy compound is 100 or more, the (a1) alicyclic epoxy compound is less likely to volatilize in an inkjet device. Furthermore, when the molecular weight or weight-average molecular weight is 790 or less, the viscosity of the (a1) alicyclic epoxy compound does not increase excessively, and thus the viscosity of the resin composition is more likely to fall within the above-mentioned range.

[0019] Here, the (a1) alicyclic epoxy compound may have only one epoxy group in the molecule. However, from the viewpoint of improving the curability of the resin composition, it is preferable that it has two or more epoxy groups. The epoxy equivalent of the (a1) alicyclic epoxy compound is preferably 50 to 500 g / eq, more preferably 60 to 250 g / eq. When the epoxy equivalent of the (a1) alicyclic epoxy compound is within this range, the curability of the resin composition tends to be good.

[0020] Specific examples of the (a1) alicyclic epoxy compound include compounds containing a cycloalkene oxide structure such as an epoxycyclohexane structure, and compounds in which an epoxy group is bonded to an alicyclic hydrocarbon via a hydrocarbon group or the like.

[0021] Among them, the (a1) alicyclic epoxy compound is preferably a compound having a cycloalkene oxide structure. When the (a1) alicyclic epoxy compound contains a cycloalkene oxide structure, the curability of the resin composition tends to be enhanced.

[0022] The cycloalkene oxide structure is a structure obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide, and is an epoxy group composed of two adjacent carbon atoms and an oxygen atom that constitute an aliphatic ring. Examples of the cycloalkene oxide include cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being particularly preferred.

[0023] The number of cycloalkene oxide structures in one molecule of the alicyclic epoxy compound (a1) having a cycloalkene oxide structure may be 1 or 2 or more. From the viewpoint of increasing the transparency of a cured product of the resin composition, the number of cycloalkene oxide structures in one molecule is preferably 2 or more.

[0024] Examples of the alicyclic epoxy compound having a cycloalkene oxide structure include compounds represented by the following general formula (a1-1):

[0025]

[0026] In general formula (a1-1), X represents a single bond or a linking group. X is selected so that the molecular weight (or weight-average molecular weight) of the compound represented by general formula (a1-1) falls within the above range. The linking group may be a divalent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), an amide group (amide bond), or a group in which a plurality of these groups are linked together.

[0027] Examples of divalent hydrocarbon groups include alkylene groups and divalent alicyclic hydrocarbon groups having 1 to 18 carbon atoms. Examples of alkylene groups having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. Examples of divalent alicyclic hydrocarbon groups include divalent cycloalkylene groups (including cycloalkylidene groups) such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene.

[0028] Among the above, X is preferably a single bond or a linking group having an oxygen atom. The linking group having an oxygen atom is more preferably -CO- (carbonyl group), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (amide group), a group in which a plurality of these groups are linked together, or a group in which one or more of these groups are linked to one or more divalent hydrocarbon groups. X is particularly preferably a single bond.

[0029] Examples of the alicyclic epoxy compound (a1) having a cycloalkene oxide structure represented by general formula (a1-1) include the following compounds. In the following formula, l represents an integer of 1 to 10, and m represents an integer of 1 to 30. R represents an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or an isopropylene group). n1 and n2 each represent an integer of 1 to 30.

[0030]

[0031] Commercially available examples of the (a1) alicyclic epoxy compound having a cycloalkene oxide structure include CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 8000, and CELLOXIDE 8010 (all manufactured by Daicel Corporation).

[0032] On the other hand, the alicyclic epoxy compound (a1) may be, for example, a compound having a structure represented by the following general formula (a1-2) or (a1-3). M in the above general formulae (a1-2) and (a1-3) ３ , M ４ , and M ５ represents an alicyclic structure, the number of carbon atoms of which is preferably 4 to 8, and more preferably 5 to 6. ２ is a single bond or a linking group. The linking group is the same as the linking group (X) in the general formula (a1-1) described above. In addition, the compounds represented by the general formulas (a1-2) and (a1-3) may have an alkyl group or the like bonded to a carbon atom constituting an alicyclic structure or an epoxy group.

[0033] Examples of the compound represented by general formula (a1-2) or (a1-3) include 3,4:7,8-diepoxybicyclo[4.3.0]nonane, limonene dioxide, etc. Examples of commercially available products of these compounds include THI-DE (manufactured by JX-TG Corporation) and LDO (manufactured by Nagase Chemtec Corporation).

[0034] Here, when the (A) epoxy compound includes an (a1) alicyclic epoxy compound, the amount of the (a1) alicyclic epoxy compound (the total amount when multiple (a1) alicyclic epoxy compounds are included) is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 50% by mass or less, relative to the total mass of the resin composition. When the amount of the (a1) alicyclic epoxy compound is 10% by mass or more, the refractive index of the resin composition is likely to be further increased. On the other hand, when the amount of the (a1) alicyclic epoxy compound is 60% by mass or less, the amounts of other components, such as the (B) oxetane compound, become relatively large, and the viscosity of the resin composition is more likely to fall within the desired range.

[0035] (a2) Monofunctional Epoxy Compound Having At Least One Aromatic Ring The (a2) monofunctional epoxy compound may be a compound having at least one aromatic ring and one epoxy group in one molecule. The (a2) monofunctional epoxy compound may partially contain a structure other than the at least one aromatic ring and the epoxy group.

[0036] Examples of the (a2) monofunctional epoxy compound include phenol or its derivatives, and reaction products of phenylphenol or the like with epichlorohydrin. Specific examples of the (a2) monofunctional epoxy compound include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, o-phenylphenol glycidyl ether, m-phenylphenol glycidyl ether, p-phenylphenol glycidyl ether, and derivatives thereof. The (a2) monofunctional epoxy compound may be a commercially available product. Examples of commercially available products include OPP-EP (manufactured by Yokkaichi Synthetic Co., Ltd.), Denacol EX-141, and Denacol EX-146 (both manufactured by Nagase ChemteX Corporation).

[0037] The epoxy equivalent of the (a2) monofunctional epoxy compound is preferably 150 to 260. When the epoxy equivalent of the (a2) monofunctional epoxy compound is within this range, the refractive index of the resulting cured product tends to be high. The epoxy equivalent of the (a2) monofunctional epoxy compound can be determined by a known method, for example, by titration.

[0038] When the (A) epoxy compound contains an (a2) monofunctional epoxy compound, the amount of the (a2) monofunctional epoxy compound (the total amount when multiple (a2) monofunctional epoxy compounds are contained) is preferably 10% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 60% by mass or less, and even more preferably 10% by mass or more and 50% by mass or less, relative to the total mass of the resin composition. When the amount of the (a2) monofunctional epoxy compound is 10% by mass or more, the refractive index of the resin composition is likely to be further increased. On the other hand, when the amount of the (a2) monofunctional epoxy compound is 60% by mass or less, the amount of other components, such as the (B) oxetane compound, becomes relatively large, and the viscosity of the resin composition is more likely to fall within the desired range.

[0039] (B) Oxetane Compound The (B) oxetane compound may be any compound having one or more oxetanyl groups in the molecule, and may be either a solid compound or a liquid compound at 25°C. However, a liquid compound is preferred from the viewpoint that the viscosity of the resin composition is more likely to fall within the desired range. When the (B) oxetane compound is liquid at 25°C, the viscosity of the (B) oxetane compound measured with an E-type viscometer at 25°C and 20 rpm is preferably 1 to 500 mPa·s, and more preferably 1 to 300 mPa·s. When the viscosity of the (B) oxetane compound is within this range, the viscosity of the resin composition is more likely to fall within the desired range.

[0040] The oxetane compound (B) is preferably a compound represented by the following general formula (B-1) or (B-2): The resin composition may contain only one type of oxetane compound (B), or may contain two or more types.

[0041]

[0042] In the above general formulas (B-1) and (B-2), Y represents an oxygen atom, a sulfur atom, or a single bond. Of these, an oxygen atom is preferred.

[0043] Also, R １ａ and R １ｂeach represents a fluorine atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group having 6 to 18 carbon atoms, a furyl group, or an ethynyl group. m and n each represent an integer of 1 to 5. R １ａ Or R １ｂ When a plurality of R are contained in one molecule, they may be the same or different. １ａ R between or adjacent １ｂ They may form a ring structure.

[0044] In addition, R in general formula (B-1) ２ａ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, an N-alkylcarbamoyl group having 2 to 6 carbon atoms, or a (meth)acryloyl group. In this specification, (meth)acryloyl represents methacryl, acryloyl, or both. The same applies to (meth)allyl, (meth)acrylic, etc.

[0045] On the other hand, R in general formula (B-2) ２ｂ represents a p-valent linking group, where p is 2, 3, or 4. ２ｂ represents, for example, a linear or branched alkylene group having 1 to 12 carbon atoms, a linear or branched poly(alkyleneoxy) group, an arylene group, a siloxane bond, or a combination thereof.

[0046] In particular, from the viewpoint of making it easier for the viscosity of the resin composition to fall within the desired range, the oxetane compound is preferably a compound represented by the following general formula (B-3) or (B-4).

[0047]

[0048] In the above general formulas (B-3) and (B-4), Y is an oxygen atom or a sulfur atom. １ｃ , R １ｄ , or R ２ｄrepresents a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, a furyl group, or a thienyl group. Among these, an alkyl group having 1 to 6 carbon atoms is preferred, from the viewpoint that the viscosity of the resin composition is more likely to fall within the desired range.

[0049] R ２ｃ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, an N-alkylcarbamoyl group having 2 to 6 carbon atoms, or a (meth)acryloyl group. Among these, an alkyl group having 1 to 10 carbon atoms is more preferred from the viewpoint of reducing the viscosity of the resin composition.

[0050] Examples of the compound represented by general formula (B-3) include 3-ethyl-3-hydroxymethyloxetane, 3-(meth)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, 4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene, [1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl-3-oxetanylmethyl)ether, isobornyloxyethyl ( Examples of the compound represented by general formula (B-4) include 3,3'-(oxybismethylene)bis(3-ethyloxetane), isobornyl(3-ethyl-3-oxetanylmethyl)ether, 2-ethylhexyl(3-ethyl-3-oxetanylmethyl)ether, ethyldiethyleneglycol(3-ethyl-3-oxetanylmethyl)ether, dicyclopentadiene(3-ethyl-3-oxetanylmethyl)ether, 3-methacryloxymethyl-3-ethyloxetane, and 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, with 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane being particularly preferred. Examples of the compound represented by general formula (B-4) include 3,3'-(oxybismethylene)bis(3-ethyloxetane).

[0051] Examples of commercially available oxetane compounds include OXT-221, OXT-121, and OXT-212 (all manufactured by Toagosei Co., Ltd.), OXBP, and HBOX (all manufactured by Ube Industries, Ltd.).

[0052] The molecular weight of the (B) oxetane compound is preferably 180 or more. When the molecular weight of the (B) oxetane compound is 180 or more, the (B) oxetane compound is less likely to volatilize in an inkjet device, and the composition of the resin composition is less likely to change. From the viewpoint of suppressing volatilization of the oxetane compound, the molecular weight of the (B) oxetane compound is preferably 190 or more, more preferably 200 or more. The upper limit of the molecular weight may be any value as long as the viscosity of the resin composition falls within the desired range, but is usually preferably 400 or less. The molecular weight may be determined from the structure, or the weight average molecular weight may be determined in the same manner as for the (A) epoxy compound.

[0053] The content of the (B) oxetane compound (when a plurality of (B) oxetane compounds are contained, the total amount of these) is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 80% by mass or less, relative to the total amount of the resin composition. When the amount of the (B) oxetane compound is within this range, the viscosity of the resin composition is more likely to fall within the desired range.

[0054] (C) Photoacid Generator The (C) photoacid generator may be any compound capable of generating an acid (active species) capable of initiating cationic polymerization upon irradiation with actinic light such as ultraviolet light (e.g., ultraviolet light). The resin composition may contain only one type of (C) photoacid generator, or may contain two or more types.

[0055] Examples of the photoacid generator (C) include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, etc. The anion moiety of these salts is BF ４ － , P.X. ６ － (X is fluorine or a fluoroalkyl group), SbF ６ － or BX ４ － (X is preferably a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups).

[0056] Examples of the aromatic sulfonium salt include bis[4-(diphenylsulfonio)phenyl]sulfide bishexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide bishexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide bistetrafluoroborate, bis[4-(diphenylsulfonio)phenyl]sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, and the like.

[0057] Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, and the like.

[0058] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrakis(pentafluorophenyl)borate, and the like.

[0059] Examples of the aromatic ammonium salts include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, and the like.

[0060] (C) Examples of commercially available photoacid generators include Irgacure 250, Irgacure 270, and Irgacure 290 (manufactured by BASF), CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-210K, CPI-310B, CPI-310FG, and CPI-400PG (manufactured by San-Apro Co., Ltd.), and SP-150, SP-170, SP-171, SP-056, SP-066, SP-130, SP-140, SP-601, SP-606, and SP-701 (manufactured by ADEKA Corporation). Of these, sulfonium salts such as Irgacure 270, Irgacure 290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-210K, CPI-310B, CPI-310FG, CPI-400PG, SP-150, SP-170, SP-171, SP-056, SP-066, SP-601, SP-606, and SP-701 are preferred.

[0061] The content of the (C) photoacid generator (when a plurality of (C) photoacid generators are contained, the total amount of these) is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.3% by mass or more and 5% by mass or less, relative to the total amount of the resin composition. When the amount of the (C) photoacid generator is within this range, the photocurability of the resin composition tends to be further improved.

[0062] Other Components In addition to the above-mentioned (A) epoxy compound, (B) oxetane compound, and (C) photoacid generator, the resin composition may further contain other components as long as the objects and effects of the present invention are not impaired. For example, the resin composition may contain a (D) sensitizer, a (E) coupling agent, a (F) leveling agent, a (G) polymerization inhibitor, and even resins other than the above-mentioned (A) epoxy compound and (B) oxetane compound (hereinafter also referred to as "other resins").

[0063] (D) The sensitizer is a compound that has the function of improving the efficiency of acid (active species) generation by (C) the photoacid generator and further accelerating the photocuring reaction of the resin composition.

[0064] Examples of the (D) sensitizer include thioxanthone compounds such as 2,4-diethylthioxanthone, benzophenone compounds such as 2,2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide, and anthracene compounds such as 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, and 9,10-bis(octanoyloxy)anthracene.

[0065] The sensitizer (D) may be a commercially available product. Examples of the sensitizer (D) include Anthracure UVS-581, Anthracure UVS-1331, and Anthracure UVS-2171 (all manufactured by Kawasaki Chemical Industries, Ltd.).

[0066] The amount of the (D) sensitizer (when multiple (D) sensitizers are included, the total amount thereof) is preferably 0.05% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 5% by mass or less, relative to the total amount of the resin composition. When the amount of the (D) sensitizer is within this range, the photocurability of the resin composition becomes even better.

[0067] The coupling agent (E) may be, for example, a silane coupling agent, etc. Examples of the coupling agent (E) include silane coupling agents having a reactive group such as an epoxy group, a carboxyl group, a methacryloyl group, or an isocyanate group.

[0068] Specific examples of the (E) coupling agent include trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. The resin composition may contain only one type of (E) coupling agent, or may contain two or more types.

[0069] The amount of the (E) coupling agent (when multiple (E) coupling agents are included, the total amount thereof) is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less, based on the total amount of the resin composition. When the amount of the (E) coupling agent is within this range, the viscosity of the resin composition is more likely to fall within the desired range.

[0070] The leveling agent (F) is a compound for adjusting the surface tension of the resin composition when it is ejected from an inkjet device and for enhancing the defoaming property. When the resin composition contains the leveling agent (F), the surface smoothness of the obtained cured product is further improved.

[0071] Examples of the (F) leveling agent include an ester-based leveling agent, a polyether-based leveling agent, a (meth)acrylic polymer, etc. The resin composition may contain only one type of (F) leveling agent, or may contain two or more types.

[0072] Examples of ester-based leveling agents include polyester-modified acrylic group-containing polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester polyol, etc. Among these, polyester-modified polydimethylsiloxane is preferred. The polyester-modified polydimethylsiloxane may be a compound having a polydimethylsiloxane skeleton and a polyester chain bonded to the polydimethylsiloxane skeleton. The polyester-modified polydimethylsiloxane may be a commercially available product, examples of which include BYK-310 and BYK-370 (both manufactured by BYK Japan).

[0073] Examples of polyether-based leveling agents include cellulose ether; pullulan; polyethylene glycol; silicone-modified polyethers such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, and polyether-modified acrylic group-containing polydimethylsiloxane; polyglycerin; polyether polyol, polyoxyethylene-polyoxypropylene condensate, polyoxyethylene alkylphenyl ether, alkyl ether derivatives such as lauryl alcohol alkoxylate, and alkyl ether sulfates. Among these, polyether-modified polydimethylsiloxane is preferred. The polyether-modified polydimethylsiloxane may be a compound having a polydimethylsiloxane skeleton and a polyether chain bonded to the polydimethylsiloxane skeleton. The polyether-modified polydimethylsiloxane may be a commercially available product, and examples thereof include BYK-333, BYK-330, BYK-302, and BYK-UV3500 (all manufactured by BYK Japan).

[0074] The (meth)acrylic polymer is, for example, a polymer obtained by homopolymerizing or copolymerizing a monomer having a (meth)acryloyl group. Examples of the monomer having a (meth)acryloyl group include (meth)acrylates having a hydroxyl group and (meth)acrylates having an alkylene oxide such as ethylene oxide. The (meth)acrylic polymer preferably contains a structure derived from such a monomer having a hydrophilic group.

[0075] The (meth)acrylic polymer may be a commercially available product, examples of which include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-380, BYK-381, BYK-392, BYK-394, and BYK-3441 (all manufactured by BYK Japan).

[0076] The amount of the (F) leveling agent (when multiple (F) leveling agents are included, the total amount thereof) is preferably 0.01% by mass or more and 3% by mass or less, and more preferably 0.05% by mass or more and 1% by mass or less, relative to the total amount of the resin composition. When the amount of the (F) leveling agent is within this range, the surface smoothness of the obtained cured product is further improved.

[0077] The polymerization inhibitor (G) is a compound having one benzene ring and one or more phenolic hydroxyl groups. Addition of the polymerization inhibitor (G) improves the storage stability of the resin composition.

[0078] Preferable examples of such (G) polymerization inhibitor include monofunctional phenolic hydroxyl group-containing compounds having one benzene ring, in which the benzene ring has one phenolic hydroxyl group; bifunctional phenolic hydroxyl group-containing compounds having one benzene ring, in which the benzene ring has two phenolic hydroxyl groups; and trifunctional or higher functional phenolic hydroxyl group-containing compounds having one benzene ring, in which the benzene ring has three or more phenolic hydroxyl groups.

[0079] Preferred examples of such a compound having a monofunctional phenolic hydroxyl group include 2,6-di-tert-butyl-p-cresol and benzenepropanoic acid 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 side chain alkyl ester, and preferred examples include 2,6-di-tert-butyl-p-cresol.

[0080] Examples of compounds having a bifunctional phenolic hydroxyl group include hydroquinone, resorcinol, tert-butylcatechol, and tert-butylhydroquinone.

[0081] An example of a compound having a tri- or higher functional phenolic hydroxyl group is pyrogallol.

[0082] The molecular weight of the polymerization inhibitor (G) having a phenolic hydroxyl group is, for example, 94 or more, preferably 100 or more, and more preferably 200 or more. The molecular weight is, for example, 1,000 or less, preferably 500 or less, and from the viewpoint of achieving both stability and curability of the resin composition, more preferably 300 or less. When the molecular weight is low, the stability of the resin composition tends to be good.

[0083] Examples of other resins include epoxy resins other than the above-mentioned (A) epoxy compound, and more specifically, include aliphatic epoxy compounds and aromatic epoxy compounds (excluding (a2) monofunctional epoxy compounds).

[0084] Examples of the aliphatic epoxy compound include diglycidyl ethers of alkanediols having 4 to 6 carbon atoms, such as 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; triglycidyl ethers of glycerin, trimethylolpropane, and the like; tetraglycidyl ether of sorbitol; hexaglycidyl ether of dipentaerythritol; diglycidyl ethers of polyethylene glycol, polypropylene glycol, and the like; and polyglycidyl ethers of alkylene oxide adducts (polyether polyols), such as propylene glycol and trimethylolpropane.

[0085] Examples of commercially available aliphatic epoxy compounds include SR-PG, SR-2EGS, SR-8EGS, SR-14BJ, and SY-25L (manufactured by Sakamoto Pharmaceutical Co., Ltd.), Epogosey 2EH, Epogosey HD(D), Epogosey NPG(D), and Epogosey BD(D) (manufactured by Yokkaichi Synthetic Co., Ltd.), and Denacol EX-121, Denacol EX-212L, and Denacol EX-214L (manufactured by Nagase ChemteX Corporation).

[0086] Examples of aromatic epoxy compounds include glycidyl ethers of polyhydric alcohols containing an aromatic ring, bisphenol A type epoxy resins, bisphenol E type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol O type epoxy resins, 2,2'-diallyl bisphenol A type epoxy resins, propylene oxide-added bisphenol A type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, biphenyl novolac type epoxy resins, and naphthalene phenol novolac type epoxy resins.

[0087] When other resins are contained, the total amount thereof is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less, relative to the total amount of the resin composition. When the amount of other epoxy compounds is within this range, the viscosity of the resin composition is more likely to fall within the desired range.

[0088] Physical Properties of Resin Composition The viscosity of the resin composition measured at 25°C and 20 rpm using an E-type viscometer may be 50 mPa·s or less, preferably 5 mPa·s or more and 50 mPa·s or less, and more preferably 10 mPa·s or more and 25 mPa·s or less. As described above, when the viscosity of the resin composition is 25 mPa·s or less, the resin composition is particularly easily ejected from an inkjet nozzle. Furthermore, the ejected droplets spread appropriately, making it easier to obtain a cured product with a smooth surface.

[0089] The resin composition was also irradiated with a UV-LED having a wavelength of 395 nm at an illuminance of 1000 mW / cm ２ , cumulative light intensity 1500 mJ / cm ２ The refractive index (nD) of the cured product at a wavelength of 589 nm may be 1.50 or more, more preferably 1.52 or more, and even more preferably 1.55 or more. As described above, when the refractive index (nD) of the cured product is 1.50 or more, the cured product can be easily used for optical applications, etc.

[0090] - Method for preparing the resin composition The resin composition may be prepared by simultaneously mixing the above-mentioned (A) epoxy compound, (B) oxetane compound, (C) photoacid generator, and other components as needed. Furthermore, the presence of coarse components in the resin composition can cause nozzle clogging in inkjet devices, etc. Therefore, if necessary, some or all of the components may be filtered individually or after mixing.

[0091] 2. Method for manufacturing a three-dimensional object using a resin composition and an optical component As described above, the resin composition can be used in three-dimensional modeling techniques, and is particularly suitable for modeling using an inkjet device for three-dimensional modeling.

[0092] The inkjet device for three-dimensional modeling may be a known device, for example, a device including a storage section for storing the resin composition, an inkjet nozzle for ejecting the resin composition, a supplying means for supplying the resin composition from the storage section side to the inkjet nozzle side, a light irradiating means for irradiating the ejected resin composition with light, and a control means for controlling these.

[0093] A three-dimensional object (cured product) can be produced using the inkjet device as follows, for example. However, the method is not limited to this. First, multiple data sets are prepared, dividing the structure of the desired three-dimensional object into multiple layers in the thickness direction. Then, a resin composition is ejected from an inkjet nozzle onto an arbitrary support based on the data for the first layer. The diameter of the droplets is appropriately selected depending on the size of the cured product, the type of inkjet device, etc. Then, the resin composition is irradiated with light to cure, producing a layered cured product (first layer). The type of light to be irradiated is appropriately selected depending on the type of acid generator. The wavelength of the light is preferably 350 to 450 nm, for example, and more preferably 365 to 405 nm. Examples of light sources include xenon lamps, carbon arc lamps, and LED lamps (e.g., UV-LEDs). Among these, LEDs are more preferable. Furthermore, the integrated light amount is, for example, 1,000 to 20,000 mJ / cm. ２If necessary, heating may be carried out before, during, or after the light irradiation.

[0094] Next, a resin composition is ejected onto the layered cured product (first layer) at a desired position based on the data for the second layer. Light irradiation is then performed in the same manner as above to cure the second layer of resin composition. These steps are then repeated to obtain a three-dimensional object of the desired shape. If necessary, a step of dropping correction droplets to adjust the surface smoothness of the three-dimensional object and curing them may be performed. After all layers have been formed, light may be irradiated again for main curing. When producing a three-dimensional object, further steps such as arranging support materials, forming support materials, or removing support materials may be performed.

[0095] The type and shape of the three-dimensional object formed by the above method are appropriately selected depending on the intended use of the three-dimensional object. Here, the cured product of the above-mentioned resin composition has a refractive index of 1.50 or more for light with a wavelength of 589 nm. Therefore, the three-dimensional object also has a similar refractive index. Three-dimensional objects with such a high refractive index are very useful as various optical components (lenses such as convex lenses, concave lenses, and Fresnel lenses, as well as prisms), semiconductor materials, sensor materials, etc.

[0096] It is preferable that the three-dimensional object (particularly an optical member) has a smooth surface, except when a step is intentionally provided. In this specification, a smooth surface means that the surface roughness Ra is 100 nm or less. More specifically, for an arbitrary area (2 mm × 2.5 mm) of the optical member, the surface roughness Ra is measured at three points in the direction perpendicular to the stacking direction of the layered cured product using a VertScan (manufactured by Mitsubishi Chemical Systems Corporation). The average value of these measurements is then used as the surface roughness Ra.

[0097] When the three-dimensional object is a lens, its size and shape are appropriately selected depending on the intended use. The lens may be, for example, a lens for a wearable device.

[0098] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0099] 1. Preparation of Materials The following compounds were used in the following Examples and Comparative Examples. The viscosity and refractive index of (A) epoxy compound and (B) oxetane compound are shown in Table 1. The viscosity is measured using an E-type viscometer at 25°C and 20 rpm, and the refractive index is the refractive index (nD) of light with a wavelength of 589 nm (D line).

[0100] (A) Epoxy Compound (a1) CEL8010: Compound represented by the following formula (manufactured by Daicel Corporation, Celoxide 8010) (a2) OPP-EP: a compound represented by the following formula (manufactured by Yokkaichi Synthetic Co., Ltd., OPP-EP)

[0101] (B) Oxetane Compound OXT-221: Compound represented by the following formula (manufactured by Toagosei Co., Ltd., OXT-221)

[0102] (C) Photoacid Generator CPI-310B: Compound represented by the following structural formula (manufactured by San-Apro Co., Ltd., CPI-310B)

[0103] (D) Sensitizer UVS-581: anthracene-based photosensitizer (manufactured by Air Water Inc., Anthracure UVS-581)

[0104] (E) Coupling Agent KBM-403: (3-glycidoxypropyl)trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403)

[0105] (F) Leveling Agent) BYK-310: Polyester-modified polydimethylsiloxane (BYK Corporation, BYK-310)

[0106] (Other compounds) (Meth)acrylic compound: 2-hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) Radical polymerization initiator: Irgacure 184 (manufactured by BASF)

[0107] <Preparation of Resin Compositions (Examples 1 to 3 and Comparative Examples 1 and 2)> The components were mixed in the compositions (mass ratios) shown in Table 1. Mixing was carried out using a stirrer while appropriately heating.

[0108] <Evaluation> The viscosity of the resin composition, the refractive index of the cured product, and the surface smoothness were measured by the methods described below.

[0109] (1) Viscosity of Resin Composition The viscosity of the resin composition was measured using an E-type viscometer at 25°C and 20 rpm. The results are shown in Table 1. The viscosity was evaluated as follows: Good: The viscosity was 50 mPa·s or less. Bad: The viscosity was more than 50 mPa·s.

[0110] (2) Measurement of refractive index of cured product Release PET (polyethylene terephthalate) was placed on alkali-free glass (EAGLE XG), and a square-shaped cutout of Teflon (registered trademark) sheet (10 mm wide, 100 μm thick) was placed on the outer periphery of the release PET. Then, each resin composition prepared in the Examples and Comparative Examples was dropped into the center of the cutout of the Teflon (registered trademark) sheet. Then, the release PET and alkali-free glass were further bonded together in this order, and the four corners were fastened with clips. Then, a UV-LED with a wavelength of 395 nm was used to measure the refractive index of the cured product. The cured product was then subjected to irradiation with an integrated light intensity of 1500 mJ / cm. ２ The photocurable resin composition was irradiated with light so that the refractive index was 1.55 or more, and a cured product (thickness: 0.1 mm) of the photocurable resin composition was obtained. The cured product was evaluated using an Abbe refractometer as follows: ⊚: Refractive index was 1.55 or more; ◯: Refractive index was 1.50 or more and less than 1.55; ×: Refractive index was less than 1.50.

[0111] (3) Surface smoothness (surface roughness) of the cured product One layer (thickness 10 μm) of the resin composition was applied to a glass substrate using an inkjet device for 3D modeling IJX-H102U (manufactured by Epson Corporation). ２ , cumulative light intensity 1500 mJ / cm ２ The cured product was further coated with a layer of resin composition and cured in the same manner as above. The cycle of coating and curing was repeated 10 times. After laminating 10 layers, the illuminance was 1000 mW / cm. ２ , cumulative light intensity 4000 mJ / cm ２The cured product was further irradiated with light having a wavelength of 395 nm so that the surface roughness Ra was measured at three points in the direction perpendicular to the lamination direction of the layered cured product using a VertScan (manufactured by Mitsubishi Chemical Systems Corporation). The average value of these measurements was used as the surface roughness Ra, and the surface roughness was evaluated according to the following criteria: ◯: The surface roughness was 100 nm or less; ×: The surface roughness was more than 100 nm.

[0112]

[0113] As shown in Table 1, photocurable resin compositions containing (A) a specific epoxy compound, (B) an oxetane compound, and (C) a photoacid generator, and having a viscosity of 50 mPa·s or less, resulted in cured products with good surface smoothness (Examples 1 to 3). This is thought to be due to the good curability and ease of printing using an inkjet device for 3D modeling. Furthermore, these cured products have a refractive index of 1.50 or higher for light with a wavelength of 589 nm, making them suitable for optical products.

[0114] On the other hand, in Comparative Example 1, in which the photocurable resin composition did not contain any of (A) the specific epoxy compound, (B) the oxetane compound, and (C) the photoacid generator, not only was the refractive index of the cured product not sufficiently increased, but the surface smoothness of the cured product was also low. It is believed that the low surface smoothness of this photocurable resin composition was due to insufficient curability, large cure shrinkage, etc.

[0115] Furthermore, in Comparative Example 2, in which the photocurable resin composition did not contain the oxetane compound (B), not only was the viscosity high but the surface smoothness of the cured product was low (Comparative Example 2). One of the reasons for this is thought to be that the photocurable resin composition was difficult to apply from an inkjet device for three-dimensional modeling, and also had poor leveling properties.

[0116] This application claims priority from Japanese Patent Application No. 2024-113378, filed July 16, 2024, the entire contents of which are incorporated herein by reference.

[0117] The photocurable resin composition of the present invention is easy to apply using a 3D printing device, and the resulting cured product has a high refractive index. Furthermore, the cured product has good surface smoothness, making it extremely useful for producing optical products and the like.

Claims

1. A composition comprising (A) an epoxy compound, (B) an oxetane compound, and (C) a photoacid generator, wherein the epoxy compound (A) is (a1) an alicyclic epoxy compound and / or (a2) a monofunctional epoxy compound having at least one aromatic ring, and has a viscosity of 50 mPa s or less as measured at 25°C and 20 rpm using an E-type viscometer, and an irradiance of 1000 mW / cm when exposed to UV-LED with a wavelength of 395 nm. ２ , cumulative light intensity 1500 mJ / cm ２ wherein the refractive index of a cured product obtained by curing the composition with the above-mentioned method is 1.50 or more when exposed to light with a wavelength of 589 nm.

2. The photocurable resin composition according to claim 1, wherein the amount of the epoxy compound (A) is 10% by mass or more and 60% by mass or less.

3. The photocurable resin composition according to claim 1, wherein the (a1) alicyclic epoxy compound is a compound containing a cycloalkene oxide structure.

4. The photocurable resin composition according to claim 1, wherein the molecular weight of the oxetane compound (B) is 180 or more.

5. The photocurable resin composition according to claim 1, wherein the amount of the oxetane compound (B) is 40% by mass or more and 90% by mass or less.

6. An optical component comprising a cured product of the photocurable resin composition according to claim 1.

7. An optical element that is a laminate of layers of cured products of a photocurable resin composition containing at least (A) an epoxy compound and (B) an oxetane compound, wherein the refractive index of the optical element at a wavelength of 589 nm is 1.50 or higher, and the surface of the optical element is smooth.

8. A method for producing a three-dimensional object, comprising: a discharge step of discharging a resin composition from an inkjet nozzle in the form of layers; and a layered cured product production step of irradiating the resin composition with light having a wavelength of 350 to 450 nm to produce a layered cured product, wherein the discharge step and the layered cured product production step are repeated, wherein the resin composition contains at least (A) an epoxy compound and (B) an oxetane compound, and the refractive index of the three-dimensional object for light with a wavelength of 589 nm is 1.50 or higher.

Images