Photocurable composition and cured product thereof

Abstract

To provide a photocurable material formulation for a lost model that has a high elastic modulus, shows small thermal expansion, has heat resistance in a certain temperature region, and is free of a photoacid generator.SOLUTION: A photocurable composition comprises curable materials formed of monofunctional (meth)acrylates each having a molecular weight of 150 or more and less than 350, and a bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400. The content of the monofunctional (meth)acrylates is 80 mol% or more and 90 mol% or less, and the monofunctional (meth)acrylates are formed of a monofunctional (meth)acrylate having an alicyclic skeleton for forming a three-dimensional crosslinked structure and a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond; or the content of the monofunctional (meth)acrylates is 60 mol% or more and 75 mol% or less, and the monofunctional (meth)acrylates are formed of a monofunctional (meth)acrylate having an alicyclic skeleton and also having quaternary carbon, and a monofunctional (meth)acrylate having a branched alkyl chain structure with 15 to 20 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable composition and a method for producing a cured product using the composition for use in a lost wax casting process. [Background technology]

[0002] In recent years, additive manufacturing technology, which creates three-dimensional objects from photocurable materials based on three-dimensional data, has become widely adopted because it can produce desired three-dimensional objects with good dimensional accuracy without creating molds or the like.

[0003] The method of creating a three-dimensional object from a photocurable material using additive modeling technology (photolithography) generally involves the following steps: A computer-controlled ultraviolet laser is selectively irradiated onto the liquid surface of a container of photocurable material to obtain the desired pattern, hardening the material to a predetermined thickness and forming a hardened layer. Liquid photocurable material is then supplied onto the hardened layer, and similarly irradiated with an ultraviolet laser to harden the photocurable material to a predetermined thickness, forming a hardened layer. These steps are then repeated to create a three-dimensional object.

[0004] To improve the defoaming of trapped bubbles and the smoothness of the liquid surface of the photocurable material applied to the curing layer, it is desirable to use materials with as low a viscosity as possible for photolithography. Photolithography is also used to create a variety of models, including design prototypes, architectural models, and medical models, as well as loss models for casting. Depending on the characteristics required for each of these applications, development of energy beam-curable resin compositions is underway, including improvements in the type and formulation of resin materials as well as the addition of functional fillers and pigments.

[0005] Patent Document 1 discloses a resin composition for modeling materials for obtaining stereolithography products that are flexible and will not break even when bent, and a method for producing a stereolithography product molded using the resin composition for modeling materials. The resin composition for modeling materials in Patent Document 1 is formulated to contain 20 to 90 parts by weight of a monofunctional monomer containing a cyclic ether skeleton, 5 parts by weight or more of a polyfunctional oligomer, and either no polyfunctional monomer or 15 parts by weight or less, per 100 parts by weight of a curable resin composition.

[0006] Patent Document 2 provides a photocurable composition that is excellent in flexural strength and flexural modulus, and further has flexural resistance, as well as excellent tensile strength and elongation. Specifically, the polymerizable compounds selected for the photocurable composition are at least one di(meth)acrylic monomer selected from di(meth)acrylic monomers that have no hydroxyl group or carboxy group in one molecule, two aromatic rings, and two (meth)acryloyloxy groups, and have a weight-average molecular weight of 400 to 800, and at least one (meth)acrylic monomer selected from (meth)acrylic monomers that have at least one ring structure and one (meth)acryloyloxy group in one molecule, and have a weight-average molecular weight of 130 to 350.

[0007] However, while Patent Document 1 aims to produce a flexible shaped object, there is a concern that when a large shaped object is produced or depending on the shape of the shaped object, the object may be unable to withstand its own weight and become distorted. Furthermore, Patent Document 2 provides a photocurable composition that uses a monomer with a specified molecular weight, thereby achieving excellent flexural strength and flexural modulus, as well as excellent flexural resistance, tensile strength, and elongation. However, because the Tg of the cured product is high, there is a concern that its disappearance may be impaired when used as a disappearance model. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2017 / 222025 [Patent Document 2] International Publication No. 2018 / 181833 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above-mentioned background art, and an object of the present invention is to provide a photocurable composition that can give a shaped object having small thermal expansion, a high elastic modulus, and heat resistance within a certain temperature range, and that does not contain a photoacid generator. [Means for solving the problem]

[0010] One aspect of the present invention provides a photocurable composition comprising a curable material consisting of a monofunctional (meth)acrylate having a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, wherein the content of the monofunctional (meth)acrylate is 80 mol % or more but less than 90 mol % of the curable material, and the monofunctional (meth)acrylate consists of a monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure and a monofunctional (meth)acrylate having an alicyclic structure with an ether bond; or the content of the monofunctional (meth)acrylate is 60 mol % or more but less than 75 mol % of the curable material, and the monofunctional (meth)acrylate consists of a monofunctional (meth)acrylate having an alicyclic skeleton and also having a quaternary carbon, and a monofunctional (meth)acrylate having a branched alkyl chain structure having 15 to 20 carbon atoms.

[0011] Another aspect of the present invention provides a cured product obtained by polymerizing the photocurable composition. Furthermore, another aspect of the present invention provides a method for producing a cured product, which comprises polymerizing the photocurable composition.

[0012] The photocurable composition of the present invention is suitable as a base material for a lost model produced by a three-dimensional optical modeling method. The method for producing a cured product of the present invention is characterized in that a photopolymerization initiator and a light absorber necessary for modeling the cured product are added to the photocurable composition, followed by polymerization to obtain a cured product. The cured product of the photocurable composition of the present invention is characterized by its ability to serve as a model for a disappearing model. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a material formulation for a photocurable elimination model that can be used in optical 3D modeling, which has low thermal expansion, a high elastic modulus, and heat resistance over a certain temperature range, and does not contain a photoacid generator. Use of the material formulation of the present invention makes it possible to achieve high mechanical properties and a low ash content due to the absence of a photoacid generator, which were not possible with conventional material formulations for photocurable elimination models that can be used in optical 3D modeling. This eliminates the need for the conventional process of producing a mold or the like and then producing an elimination model by injection molding. This makes it possible to produce highly accurate castings with few defects such as casting cavities in a short period of time from elimination models produced directly by optical 3D modeling. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a modeling apparatus using a free surface method. DETAILED DESCRIPTION OF THE INVENTION

[0015] (First embodiment) A first embodiment of the present invention will be described in detail below. First, a photocurable composition according to the first embodiment of the present invention will be described. The photocurable composition according to the first embodiment of the present invention is a photocurable composition containing a curable material consisting of a monofunctional (meth)acrylate having a molecular weight of 150 or more and less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400, characterized in that the content of the monofunctional (meth)acrylate is 80 mol % or more and 90 mol % or less of the curable material, and the monofunctional (meth)acrylate is composed of a monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure and a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond.

[0016] There are no particular restrictions on the curable material, as long as it is composed of a monofunctional (meth)acrylate with a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate with a molecular weight of 200 or more but less than 400. As the molecular weight decreases, the volatility of the material increases, leading to formulation changes during storage. Therefore, the molecular weight of the monofunctional (meth)acrylate is 150 or more, and the molecular weight of the bifunctional (meth)acrylate is 200 or more. Furthermore, as the molecular weight increases, the proportion of flexible moieties such as ethylene glycol chains and propylene glycol chains increases, reducing the proportion of the main skeleton moiety necessary for expressing mechanical properties such as alicyclic skeletons, resulting in reduced mechanical properties as a material for elimination models. Therefore, the molecular weight of the monofunctional (meth)acrylate is less than 350, and the molecular weight of the bifunctional (meth)acrylate is less than 400. In the photocurable composition of this embodiment, the content of the curable material is 60% by weight or more and 99.5% by weight or less, taking into consideration the curability, mechanical properties of the cured product, etc. Taking into consideration the deterioration of mechanical properties, etc., the content of the curable material is preferably 80% by weight or more and 99.5% by weight or less.

[0017] In the photocurable composition of this embodiment, the content of the monofunctional (meth)acrylate in the curable material is 80 mol % or more and 90 mol % or less in order to provide a cured product as an elimination model having a high elastic modulus, small thermal expansion, and heat resistance within a certain temperature range.

[0018] The monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is not particularly limited as long as the cured product of the photocurable composition becomes a disappearance model with low thermal expansion, high elastic modulus, and heat resistance over a certain temperature range. Examples of the monofunctional (meth)acrylate having an alicyclic skeleton include monofunctional (meth)acrylates containing an adamantane skeleton, a norbornane skeleton, a dicyclopentadiene skeleton, etc. Specific examples include alicyclic (meth)acrylates that form a three-dimensional crosslinked structure, such as isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 3-hydroxy-1-adamantyl (meth)acrylate, and 1-adamantyl (meth)acrylate. The photocurable composition may contain one type of monofunctional (meth)acrylate having an alicyclic skeleton, or may contain multiple types of monofunctional (meth)acrylates simultaneously. Unless otherwise specified, the alicyclic skeleton of this embodiment is a molecular structure consisting of carbon atoms and hydrogen atoms, and does not contain heteroatoms such as oxygen atoms and nitrogen atoms.

[0019] The monofunctional (meth)acrylate containing an alicyclic structure having an ether bond is not particularly limited as long as the cured product of the photocurable composition has low thermal expansion, a high elastic modulus, and heat resistance over a certain temperature range, making it suitable for use as an evaporative model. Examples of monofunctional (meth)acrylates containing an alicyclic structure having an ether bond include monofunctional (meth)acrylates containing a dioxane skeleton, a tetrahydropyran skeleton, a tetrahydrofuran skeleton, etc. When the photocurable composition of this embodiment contains a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, the structure derived from the monofunctional (meth)acrylate having an alicyclic skeleton ensures a high elastic modulus, low thermal expansion, and heat resistance over a certain temperature range of the cured product. Furthermore, the structure derived from the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond enables improved adhesion between layers when molded by a stereolithography method. This enables improvements in not only the flexural modulus of the cured product but also its flexural strength. Specific examples include monofunctional (meth)acrylates containing an alicyclic structure having an ether bond, such as tetrahydro-2H-pyran-2-yl acrylate, tetrahydrofurfuryl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate. The photocurable composition may contain one or more types of monofunctional (meth)acrylates containing an alicyclic structure having an ether bond. In order to provide a cured product as an elimination model having small thermal expansion, a higher elastic modulus, and heat resistance over a certain temperature range, it is preferred that the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond is tetrahydro-2H-pyran-2-yl acrylate or cyclic trimethylolpropane formal (meth)acrylate.

[0020] The content ratio of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure and the monofunctional (meth)acrylate containing an alicyclic structure with an ether bond in the photocurable composition is not particularly limited as long as the photocurable composition can provide a cured product as a loss model with low thermal expansion, high elastic modulus, and heat resistance within a certain temperature range. The "certain temperature range" here refers to the temperature range (60°C or less) to which the cured product is exposed in processes prior to the mold baking process. However, if the content of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is high, the heat resistance of the cured product may exceed the temperature range to which the cured product is exposed in the mold baking process. Furthermore, this may result in reduced interlayer adhesion when molded using a stereolithography method. Therefore, the content of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is preferably 30 mol% to 80 mol% of the curable material. Furthermore, in order to provide a cured product that has small thermal expansion, a higher elastic modulus, heat resistance within a certain temperature range, and improved adhesion between layers during production, it is more preferable that the content of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is 40 mol % or more and 50 mol % or less of the curable material.

[0021] The bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 is not particularly limited as long as it can provide a cured product as a loss model of the photocurable composition having low thermal expansion, high elastic modulus, and heat resistance over a certain temperature range. In bifunctional (meth)acrylates having a molecular weight of 200 or more but less than 400, if the volume ratio of the linear molecular structure to which the (meth)acryloyl groups are bonded in the cured product increases, there is a concern that the cured product will have a decreased elastic modulus and an increased thermal expansion coefficient. On the other hand, if a linear molecular structure is not present in the photocurable composition, only the (meth)acryloyl group bonded to the alicyclic skeleton will participate in the polymerization reaction, and there is a concern that the polymerization reactivity will decrease due to steric hindrance, etc. Therefore, the bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 is preferably a bifunctional (meth)acrylate having a side chain having 1 to 6 carbon atoms selected from a linear alkyl chain, a branched alkyl chain, an ethylene glycol chain, and a propylene glycol chain.Specifically, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxan-2-yl]-2,2-dimethylethyl (meth)acrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, alkylene oxide-modified neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, 1,3-adamantanedimethanol di(meth)acrylate, propoxylated neopentyl glycol Di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2, Examples of bifunctional (meth)acrylates include 2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 1,1-bis(4-(meth)acryloxyethoxyphenyl)methane, 1,1-bis(4-(meth)acryloxydiethoxyphenyl)methane, 1,1-bis(4-(meth)acryloxyethoxyphenyl)sulfone, and 1,1-bis(4-(meth)acryloxydiethoxyphenyl)sulfone. The photocurable composition may contain one type of bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400, or may contain multiple types of bifunctional (meth)acrylates simultaneously.

[0022] The photocurable composition of this embodiment may further contain, as necessary, a photopolymerization initiator, a light absorber, a polymerization inhibitor, a photosensitizer, a light resistance stabilizer, a heat resistance stabilizer, an antioxidant, a mold release agent, an anti-fungal agent, etc. Furthermore, the photocurable composition of this embodiment is characterized in that, when a cured product of the photocurable composition is used as a loss model, the photocurable composition does not contain a photoacid generator in order to reduce the amount of ash remaining after the loss model is burned.

[0023] Examples of photopolymerization initiators that generate radical species upon irradiation with light include, but are not limited to, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4'-diphenylbenzophenone, and 4,4'-diphenoxybenzophenone.

[0024] The amount of polymerization initiator added to the photocurable composition is preferably in the range of 0.01% by mass to 10.00% by mass relative to the photocurable composition. The polymerization initiator may be used alone or in combination of two or more types. The amount of polymerization initiator added to the photocurable composition may be appropriately selected depending on the light irradiation dose and additional heating temperature. It may also be adjusted depending on the target average molecular weight of the resulting polymer. Furthermore, the critical exposure dose and penetration depth in the stereolithography method may be adjusted by using the initiator in combination with a light absorber, which will be described later.

[0025] The light absorber can be selected appropriately depending on the wavelength of the UV light used in the optical three-dimensional modeling method. However, when inorganic materials such as inorganic fillers are used as a fading model, ash remains when the cured product of the photocurable composition is burned, so it is desirable to select an organic material. Furthermore, photosensitizers and light-resistance stabilizers, which will be described later, can also be used as light absorbers, and there are no particular restrictions on them as long as they can control the transparency. Examples of materials other than photosensitizers and light-resistance stabilizers include organic polymer fillers, but there are no particular restrictions on them.

[0026] The polymerization inhibitor acts as a polymerization suppressor during reaction or storage, and examples thereof include hydroquinone-based polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, hydroquinone monoethyl ether, hydroquinone monopropyl ether, hydroquinone monobutyl ether, hydroquinone monopentyl ether, hydroquinone monohexyl ether, hydroquinone monooctyl ether, and hydroquinone monoheptyl ether, and phenol-based polymerization inhibitors having a substituent such as 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, but are not limited to these.

[0027] The amount of the polymerization inhibitor contained in the photocurable composition is preferably in the range of 0.01% by mass to 1.00% by mass, based on the photocurable composition. Only one polymerization inhibitor may be used, or two or more polymerization inhibitors may be used in combination.

[0028] Examples of photosensitizers include benzophenone, 4,4-diethylaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, isoamyl p-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate, benzoin, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, 2,2-diethoxyacetophenone, methyl o-benzoylbenzoate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and acylphosphine oxide. Examples of polymerization inhibitors include, but are not limited to, those described above as polymerization inhibitors during reaction and storage. Furthermore, a single polymerization inhibitor may be used alone, or two or more polymerization inhibitors may be used in combination. Considering the minimal coloration of the cured product, it is preferable to use a combination of hydroquinone-based polymerization inhibitors. The amount added is preferably in the range of 0.01% by mass to 10.00% by mass of the photocurable composition.

[0029] There are no particular restrictions on the light resistance stabilizer as long as it does not have a significant effect on the properties of the cured product, and examples thereof include 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2,2'-methylene Examples of suitable light-resistant stabilizers include benzotriazole compounds such as bis[6-(2H-benzotriazol-2-yl)]-4-(1,1,3,3-tetramethylbutyl)phenol and 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol; cyanoacrylate compounds such as ethyl 2-cyano-3,3-diphenylacrylate and 2-ethylhexyl 2-cyano-3,3-diphenylacrylate; triazine compounds; and benzophenone compounds such as octabenzone, 2,2'-4,4'-tetrahydroxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzoenone. The light-resistant stabilizer may also function as a photosensitizer, in which case it may not be necessary to add a photosensitizer. The light-resistant stabilizer may also function as a light absorber, in which case it is desirable to adjust it to meet the curing characteristics required for the stereolithography method. The amount added is preferably in the range of 0.01% by mass to 5.00% by mass based on the photocurable composition.

[0030] The photocurable composition of this embodiment may contain other polymerizable or non-polymerizable materials polymerizable with the photocurable composition to adjust the viscosity or provide additional functionality, as long as they provide a material for a cured product as a loss model with low thermal expansion, a high elastic modulus, and heat resistance over a certain temperature range. The amount of polymerizable material added varies depending on the photocurable composition to which it is added, but is preferably in the range of 0.1 mol % to 20.0 mol %. If the amount is too small, the effect of adding the polymerizable material is not obtained, while if the amount is too large, the mechanical properties of the cured product when the photocurable composition is cured are reduced. Therefore, the amount is preferably 0.1 mol % to 10.0 mol %. The polymerizable material is not particularly limited, and may be a monofunctional or difunctional or higher functional (meth)acrylate compound.

[0031] Examples of monofunctional or bifunctional or higher functional (meth)acrylate compounds include 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isooctyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, ethylene glycol di(meth)acrylate, and propylene glycol. Di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane di(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate acrylate, tetrahydrofurfuryl (meth)acrylate, morpholine (meth)acrylate, phenylglycidyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, tridecyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, tricyclodecane (meth)acrylate, isobornyl (meth)acrylate, dicyclopentaerythritol, Dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentenyloxy methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, 1-adamantyl methacrylate, cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,Examples of suitable di(meth)acrylates include 3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, dioxane glycol diacrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, alkylene oxide-modified 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)diacrylate, alkylene oxide-modified neopentyl glycol di(meth)diacrylate, hydroxycipivalic acid neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and ethylene oxide-modified bisphenol A di(meth)acrylate, but are not limited to these, and multiple di(meth)acrylates may be used simultaneously.

[0032] There are no particular restrictions on the non-polymerizable material, but considering the adhesion and compatibility when forming a cured product as a lost model using a stereolithography method, alcohols of (meth)acrylates contained in the photocurable composition are desirable. Specific examples include, but are not limited to, diethylene glycol, dipropylene glycol, tricyclodecane dimethanol, 2-ethyl-2-adamantanemethanol, 1-adamantanemethanol, cyclohexane-1,4-dimethanol, cyclohexane-1,3-dimethanol, tricyclodecane dimethylol, 1,6-hexanediol, neopentyl glycol, 1,9-nonanediol, cyclic trimethylolpropane formal, and trimethylolpropane formaldehyde acetals.

[0033] The method for preparing the photocurable composition of this embodiment is not particularly limited, and the simplest method is to weigh out all the materials and then stir them. If it is difficult to mix them uniformly by stirring alone, the composition may be prepared by heating and stirring, or by diluting with a solvent and then stirring, and then removing the solvent.

[0034] Next, the cured product of this embodiment will be described. The cured product of this embodiment is a cured product formed by polymerization of polymerizable functional groups of the curable material contained in the photocurable composition of this embodiment. The cured product of this embodiment is characterized in that, in the curable material comprising at least a monofunctional (meth)acrylate having a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, the monofunctional (meth)acrylate accounts for 80 mol % or more but less than 90 mol % of the curable material, and the monofunctional (meth)acrylate has an alicyclic skeleton that forms a three-dimensional crosslinked structure, the monofunctional (meth)acrylate has an alicyclic structure having an ether bond, and the polymerizable functional groups contained in the bifunctional (meth)acrylate are each polymerized.

[0035] The method for optically fabricating a three-dimensional object using the photocurable composition of the present embodiment can be a conventionally known optically fabricating method and apparatus. Preferably, the method is a method for finally obtaining a three-dimensional object by repeating the process of selectively irradiating the photocurable composition with an active energy ray to form a cured layer having a desired pattern.

[0036] Examples of active energy rays (also referred to as light energy) include ultraviolet rays, electron beams, X-rays, radiation, high frequency waves, etc. Among these, ultraviolet rays having a wavelength of 300 to 430 nm are preferably used from an economical viewpoint, and examples of light sources that can be used for the active energy rays include ultraviolet lasers (e.g., semiconductor-pumped solid-state lasers, Ar lasers, He—Cd lasers, etc.), high-pressure mercury lamps, ultra-high-pressure mercury lamps, mercury lamps, xenon lamps, halogen lamps, metal halide lamps, ultraviolet LEDs (light-emitting diodes), and fluorescent lamps.

[0037] When forming each cured resin layer having a predetermined pattern by irradiating an active energy ray onto a modeling surface made of a photocurable composition, the cured resin layer may be formed by a pointillist or line drawing method using an active energy ray focused into a point shape, such as a laser beam. Alternatively, a modeling method may be employed in which the cured resin layer is formed by irradiating the active energy ray in a planar manner onto the modeling surface through a planar drawing mask formed by arranging a plurality of microscopic optical shutters, such as a liquid crystal shutter or a digital micromirror shutter (DMD).

[0038] As a representative example of a preferred stereolithography method, the free surface method will be described. FIG. 1 shows an example of the configuration of a modeling apparatus 100 using the free surface method. The modeling apparatus 100 has a tank 11 that contains a liquid curable resin composition 10. Inside the tank 11, a modeling stage 12 is provided so as to be drivable in the vertical direction by a drive shaft 13. An active energy beam 15 for curing the curable resin composition 10, emitted from a light source 14, is irradiated onto the curable resin composition 10 in accordance with slice data generated based on three-dimensional shape data of the object to be manufactured (a three-dimensional model). The irradiation position of the active energy beam 15 is changed by a galvanometer mirror 16 controlled by a control unit 18, and the surface of the tank 11 is scanned. In FIG. 1, the scanning range is indicated by a thick dashed line.

[0039] The depth (thickness) d from the surface of the photocurable resin composition 10 cured by the active energy beam 15 is a value determined based on the settings made when the slice data was generated, and affects the accuracy of the resulting article (the reproducibility of the three-dimensional shape data of the article to be formed). The thickness d is achieved by the control unit 18 controlling the drive amount of the drive shaft 13.

[0040] First, the control unit 18 controls the drive shaft 13 based on the settings, and the curable resin composition is placed on the stage 12 to a thickness d. The liquid curable resin composition on the stage 12 is selectively irradiated with active energy rays 15 based on the slice data to form a cured layer having the desired pattern. Next, the stage 12 is moved in the direction of the white arrow, and uncured curable resin composition is placed on the surface of the cured layer to a thickness d. Then, active energy rays 15 are irradiated based on the slice data to form a cured product integrated with the previously formed cured layer. By repeating this layer-by-layer curing process, the desired three-dimensional object 17 can be obtained.

[0041] Similar to the free liquid level method, modeling using the regulated liquid level method is also preferred. A modeling apparatus using the regulated liquid level method is configured as shown in FIG. 1, with the stage 12 of the modeling apparatus 100 being arranged to raise the model 17 above the liquid surface, and a light irradiation means being arranged below the vat 11. A typical modeling example using the regulated liquid level method is as follows: First, a support surface of a freely movable support stage is set at a predetermined distance from the bottom surface of a vat containing a curable resin composition, and the curable resin composition is placed between the support surface of the support stage and the bottom surface of the vat. Next, a laser light source or a projector selectively irradiates light from the bottom side of the vat containing the curable resin composition onto the curable resin composition between the stage support surface and the bottom surface of the vat in accordance with slice data. The light irradiation cures the curable resin composition between the stage support surface and the bottom surface of the vat, forming a solid cured layer. The support stage is then raised, and the cured layer is peeled off from the bottom surface of the vat.

[0042] Next, the height of the support stage is adjusted so that the distance between the cured layer formed on the support stage and the bottom of the vat is a predetermined distance. Then, as before, a curable resin composition is placed between the bottom of the vat and the cured layer, and light is irradiated according to the slice data to form a new cured layer between the cured layer and the bottom of the vat. By repeating this process multiple times, a molded object 17 can be obtained, consisting of multiple cured layers stacked together. The shaped object 17 thus obtained is removed from the tank 11, and any unreacted curable resin composition remaining on its surface is removed. After that, the desired article can be obtained by carrying out post-processing as necessary.

[0043] Post-processing includes cleaning, post-curing, cutting, polishing, assembly, and the like. As a cleaning agent used for cleaning, an alcohol-based organic solvent, typified by alcohols such as isopropyl alcohol and ethyl alcohol, can be used. In addition, a ketone-based organic solvent, typified by acetone, ethyl acetate, methyl ethyl ketone, etc., or an aliphatic organic solvent, typified by terpenes, can also be used. After washing, post-curing may be performed as needed by light irradiation, heat irradiation, or both. Post-curing can cure any unreacted curable resin composition that may remain on the surface or inside of the three-dimensional object, thereby reducing stickiness on the surface of the three-dimensional object and improving the initial strength of the three-dimensional object.

[0044] (Second embodiment) A second embodiment of the present invention will be described in detail below. First, a photocurable composition according to the second embodiment of the present invention will be described. The photocurable composition according to the second embodiment of the present invention is a photocurable composition containing a curable material consisting of at least a monofunctional (meth)acrylate having a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, wherein the content of the monofunctional (meth)acrylate is 60 mol % or more but less than 75 mol % of the curable material, and the monofunctional (meth)acrylate consists of a monofunctional (meth)acrylate having an alicyclic skeleton and also having a quaternary carbon, and a monofunctional (meth)acrylate having a branched alkyl chain structure having 15 to 20 carbon atoms.

[0045] The photocurable composition of this embodiment is not particularly limited as long as it is a composition comprising a monofunctional (meth)acrylate having a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, but as the molecular weight decreases, the volatility of the material increases, leading to formulation changes during storage, so it is preferable for the composition to have a molecular weight of 150 or more. Furthermore, as the molecular weight increases, the proportion of flexible moieties such as ethylene glycol chains and propylene glycol chains increases, and the proportion of main skeleton moieties necessary for expressing mechanical properties such as alicyclic skeletons decreases, resulting in reduced mechanical properties as a material for elimination models. Therefore, it is preferable for the monofunctional (meth)acrylate to have a molecular weight of less than 350, and for the bifunctional (meth)acrylate to have a molecular weight of less than 400.

[0046] In the photocurable composition of this embodiment, the content of the monofunctional (meth)acrylate is not particularly limited, but in order to provide a material formulation for a disappearance model that has a high elastic modulus, small thermal expansion, and heat resistance in a certain temperature range, it is preferable that the content be 50 mol % to 95 mol % of the curable material. More preferably, the content be 60 mol % to 75 mol % of the curable material, which can provide a material for a disappearance model that has a high elastic modulus, small thermal expansion, and heat resistance in a certain temperature range.

[0047] The monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon is not particularly limited as long as it is a material for a fading model that has a high elastic modulus, small thermal expansion, and heat resistance in a certain temperature range, and specific examples include monofunctional (meth)acrylates having an alicyclic skeleton and a quaternary carbon, such as isobornyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, trimethylcyclohexane (meth)acrylate, t-butylcyclohexane (meth)acrylate, and cyclic trimethylolpropane formal acrylate. Furthermore, as long as a material for a fading model that has a high elastic modulus, small thermal expansion, and heat resistance in a certain temperature range is provided, there is no problem in using one type or multiple types simultaneously.

[0048] The monofunctional (meth)acrylate having a branched alkyl chain structure is not particularly limited as long as it can provide a elimination model material having a high elastic modulus, small expansion, and heat resistance over a certain temperature range. As the alkyl chain length increases, the heat resistance over a certain temperature range decreases and the thermal expansion increases. On the other hand, as the alkyl chain length decreases, the heat resistance over a certain temperature range increases. Therefore, it is not possible to provide a elimination model material having a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range. Furthermore, by using a branched alkyl chain structure rather than a linear alkyl chain, it is possible to provide a elimination model material having a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range. Therefore, the number of carbon atoms in the branched alkyl chain is preferably 10 to 25. To achieve a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range, it is more preferable that the number of carbon atoms in the branched alkyl chain be 15 to 20. Specific examples of monofunctional (meth)acrylates having a branched alkyl chain structure include isostearyl (meth)acrylate.

[0049] The content ratio of the monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon to the monofunctional (meth)acrylate having a branched alkyl chain structure is not particularly limited as long as it provides a fading model material with a high elastic modulus, low thermal expansion, and heat resistance over a certain temperature range. However, if the content of the monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon increases, the heat resistance over a certain temperature range required for the fading model material may exceed that temperature range, and the adhesion between layers may decrease when molded using a stereolithography method. Therefore, the content of the monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon is preferably 20 mol% or more and 70 mol% or less of the curable material. In order to provide a material that has a higher elastic modulus, small thermal expansion, heat resistance within a certain temperature range, and improved adhesion between layers, it is more preferable that the content of the monofunctional (meth)acrylate having an alicyclic skeleton and also a quaternary carbon is 35 mol % or more and 55 mol % or less of the curable material.

[0050] As the bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400, the bifunctional (meth)acrylates having a molecular weight of 200 or more and less than 400 exemplified in the first embodiment can be used.

[0051] The photocurable composition may further contain additives such as photopolymerization initiators, light absorbers, polymerization inhibitors, photosensitizers, light stabilizers, heat stabilizers, antioxidants, release agents, and antifungal agents, as necessary. Furthermore, like the photocurable composition of the first embodiment, the photocurable composition of this embodiment is characterized in that, when a cured product of the photocurable composition is used as a loss model, it does not contain a photoacid generator in order to reduce the amount of ash remaining after the loss model is burned. The various additives to be contained as necessary can be the same as those described in the first embodiment.

[0052] The method for preparing the photocurable composition of this embodiment is not particularly limited, and the simplest method is to weigh out all the materials and then stir them. If it is difficult to mix them uniformly by stirring alone, the composition may be prepared by heating and stirring or by diluting with a solvent and then removing the solvent.

[0053] Next, the cured product of this embodiment will be described. The cured product of this embodiment is a cured product obtained by copolymerization of polymerizable functional groups of the curable materials in the photocurable composition of this embodiment. The cured product of this embodiment is characterized in that, in the photocurable composition containing curable materials consisting of at least a monofunctional (meth)acrylate having a molecular weight of 150 or more but less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, the content of the monofunctional (meth)acrylate is 60 mol % or more but less than 75 mol % of the curable materials, and the monofunctional (meth)acrylate is a monofunctional (meth)acrylate having an alicyclic skeleton and also having a quaternary carbon, and a monofunctional (meth)acrylate having a branched alkyl chain structure with 15 to 20 carbon atoms, and the polymerizable functional groups of the curable materials in the photocurable composition are copolymerized.

[0054] The method for optical three-dimensional modeling using the photocurable composition of this embodiment can be any of the conventionally known optical three-dimensional modeling methods and apparatuses described in Embodiment 1. Preferably, the method involves selectively irradiating the photocurable composition with active energy rays to form a cured layer having a desired pattern, then placing an uncured liquid photocurable resin composition on the cured layer, and similarly irradiating it with active energy rays to form a new cured layer continuous with the cured layer, repeating this lamination process to finally obtain the desired three-dimensional object.

[0055] The active energy ray suitable for shaping, the method of applying the active energy ray, the shaping method, etc. are also the same as those in the first embodiment. [Example]

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples described below as long as it does not depart from the gist of the invention.

[0057] Example 1 10.5 g of isobornyl acrylate (Tokyo Chemical Industry Co., Ltd.) as a monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure, 9.5 g of a monofunctional (meth)acrylate containing an alicyclic structure with an ether bond (trade name: Sartomer SR531, Arkema), 4.0 g of a bifunctional (meth)acrylate with a molecular weight of 200 to less than 400 (trade name: KAYARAD R-604, Nippon Kayaku), and 0.24 g of a polymerization initiator (trade name: Omnirad184, IGM Resins BV) were weighed into a brown glass bottle and stirred. Using the resulting photocurable composition, evaluation samples were prepared and evaluated according to the following evaluation sample preparation method (2a). The evaluation results are shown in Table 3.

[0058] Examples 2 to 9 A photocurable composition was obtained in the same manner as in Example 1, except that the monofunctional (meth)acrylate having an alicyclic skeleton, the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, and the bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 were used in the compounds and addition ratios shown in Table 1. Evaluation samples were prepared using the obtained photocurable composition according to the evaluation sample preparation method (2a) below, and evaluated. The evaluation results are shown in Table 3.

[0059] Example 10 A photocurable composition was prepared in the same manner as in Example 1, except that the monofunctional (meth)acrylate having an alicyclic skeleton, the monofunctional (meth)acrylate containing an alicyclic structure with an ether bond, and the bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 were used in the compounds and addition ratios listed in Table 1, 1.92 g of a polymerization initiator (trade name: OmniradTPO, manufactured by IGM Resins BV) were used, and 0.768 g of 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as a light absorber. Evaluation samples were prepared using the resulting photocurable composition according to the evaluation sample preparation method (2b) below and evaluated. The evaluation results are shown in Table 3.

[0060] (Comparative Examples 1 to 13) A photocurable composition was obtained in the same manner as in Example 1, except that the monofunctional (meth)acrylate having an alicyclic skeleton, the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, and the bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 were used in the compounds and addition ratios shown in Table 2. Evaluation samples were prepared using the obtained photocurable composition according to the evaluation sample preparation method (2a) below, and evaluated. The evaluation results are shown in Table 4.

[0061] (Production of evaluation samples and evaluation method) (1) Evaluation method for evaluation samples The deflection temperature under load was measured using a heat deformation tester (product name: HDT Tester 3M-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the flexural modulus and flexural strength were measured using a material testing machine (product name: Universal Material Tester No. 5581, manufactured by Instron Japan Company Limited). Evaluation was performed using a sample size (4 mm × 10 mm × 80 mm) and under test conditions in accordance with JIS standards, and the evaluation results were judged according to the following criteria.

[0062] Deflection temperature under load A: 50℃ or higher and less than 60℃ B: 45℃ or higher and lower than 50℃ C: Less than 45℃ or more than 60℃ Flexural modulus A:2.5GPa or more B: 2.0GPa or more and less than 2.5GPa C: Less than 2.0 GPa Bending strength A:90MPa or more B: 60MPa or more and less than 90MPa C: Less than 60 MPa

[0063] The linear expansion coefficient was measured using a thermal analyzer (product name: TMA-Q400, manufactured by TA Instruments). Samples were cut out into cubes with sides of approximately 5 mm and measured at a heating rate of 10°C / min. The linear expansion coefficient was calculated in the range of 20°C to 40°C and evaluated according to the following criteria. A: Less than 100 ppm B: 100 ppm or more and less than 130 ppm C:130ppm or more

[0064] (2a) Method for producing samples for evaluation of cast-molded objects A 4mm x 10mm x 80mm framed mold was placed on a quartz plate coated with a release agent, and the photocurable composition was poured into the mold, sandwiched between the quartz plates coated with the release agent. The mold was irradiated with 10mW (evaluated with a 365nm sensor manufactured by Ushio) for 120 seconds three times (on the front, back, and front) using a UV irradiator (product name: EX250, manufactured by HOYA). The prismatic object was then released from the mold to obtain a sample for evaluation. The resulting sample for evaluation was heat-treated at 50°C for 1 hour and then at 80°C for another 1 hour to obtain a cast-molded sample for evaluation.

[0065] (2b) Method for producing evaluation samples by optical 3D modeling A 4mm x 10mm x 80mm rectangular pillar was created using a DWS DIGITALWAX020X. The laser scanning speed was 2500mm / s, the laser scanning interval was 60μm, and the edge was cut once to obtain the model. After washing the obtained evaluation sample with 2-propanol, it was subjected to secondary curing by irradiating it with 405nm light at 60°C for 60 minutes using a Formlabs FormCure. It was then heat-treated at 50°C for 1 hour and then at 100°C for another 1 hour to obtain the evaluation sample.

[0066] [Table 1]

[0067] [Table 2]

[0068] The compounds represented by the abbreviations in Tables 1 and 2 are shown below. In Tables 1 and 2, "-" indicates that the compound was not used. IBA: Isobornyl acrylate (Tokyo Chemical Industry Co., Ltd., molecular weight 208) MADA: Adamantyl acrylate (trade name: MADA, manufactured by Osaka Organic Chemical Industry Co., Ltd., molecular weight 220) TCDA: dicyclopentanyl acrylate (trade name: FA-513AS, manufactured by Hitachi Chemical Co., Ltd., molecular weight 206) TMHA: 3,3,5-trimethylcyclohexanol acrylate (trade name: SR420NS, manufactured by Arkema, molecular weight 210) PEGDM: Ethoxylated ethylhexyl polyethylene glycol methacrylate (trade name: EH-4E, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 374) TMPFA: cyclic trimethylolpropane formal acrylate (trade name: Sartomer SR531, manufactured by Arkema, molecular weight 200) EEEA: 2-(2-ethoxyethoxy)ethyl acrylate (Tokyo Chemical Industry Co., Ltd., molecular weight 188) DEGDM: Diethylene glycol dimethacrylate (trade name: 2G, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 242) TCDDA: Tricyclodecane dimethanol diacrylate (Product name: KAYARAD R-684, manufactured by Nippon Kayaku, molecular weight 304) DiODA: 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxan-2-yl]-2,2-dimethylethyl acrylate (trade name: KAYARAD R-604, manufactured by Nippon Kayaku Co., Ltd., molecular weight 326) NPGDA: Neopentyl glycol diacrylate (trade name: A-NPG, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 212) NDA: 1,9-nonanediol diacrylate (trade name: A-NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 268) TEGDA: polyethylene glycol #200 diacrylate (trade name: A-200, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 302) PEG400DA: polyethylene glycol #400 diacrylate (trade name: A-400, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 523) BDDA: 1,4-butanediol diacrylate (trade name: SR213, manufactured by Arkema, molecular weight 198)

[0069] In terms of deflection temperature under load, flexural modulus, flexural strength, and coefficient of linear expansion, if the evaluation result is C, it is undesirable as a material for fading models, as it increases concerns about maintaining the shape and mold cracking, etc., and it is preferable that the evaluation result is A or B.

[0070] [Table 3]

[0071] [Table 4]

[0072] (Procedure for preparing and evaluating evaluation samples) (1) Preparation of photocurable composition As described in the following Examples 11 to 23 and Comparative Examples 14 to 23, photocurable compositions were prepared by thoroughly stirring each material in the amounts shown in Tables 5 and 6 below.

[0073] (2) Evaluation method for evaluation samples Evaluation samples were prepared in the same manner as in the first embodiment, and the deflection temperature under load, flexural modulus, flexural strength, and coefficient of linear expansion were evaluated according to the same criteria as in the first embodiment.

[0074] (2a) Method for producing samples for evaluation of cast-molded objects An evaluation sample of the cast-molded object was also prepared in the same manner as in the first embodiment.

[0075] (2b) Method for producing evaluation samples by optical 3D modeling An evaluation sample was also fabricated by stereolithography in the same manner as in the first embodiment.

[0076] Example 11 8.0 g of isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon atom, 7.4 g of isostearyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a monofunctional (meth)acrylate having a branched alkyl chain structure, 8.0 g of diethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400, and 0.24 g of 1-hydroxycyclohexyl phenyl ketone (trade name: Omnirad 184) (manufactured by IGM Resins BV) as a polymerization initiator were weighed into a brown glass bottle and stirred. A sample was prepared from the resulting photocurable composition using the evaluation sample preparation method (2a) described above and evaluated. The evaluation results are shown in Table 5.

[0077] Examples 12 to 22 The photocurable material was weighed out in the proportions shown in Table 5 using the method described in Example 11, and 1.0 wt% of Omnirad 184 was weighed out as a polymerization initiator relative to the photocurable material. The mixture was then placed in a brown bottle and stirred. Samples of the resulting photocurable composition were prepared using the evaluation sample preparation method (2a) and evaluated. The evaluation results are shown in Table 5.

[0078] Example 23 80.2 g of isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon atom, 74.2 g of isostearyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a monofunctional (meth)acrylate having a branched alkyl chain structure, 80.1 g of diethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a bifunctional (meth)acrylate having a molecular weight of 200 to 400, 1.92 g of Omnirad TPO (manufactured by IGM Resins BV) as a polymerization initiator, and 0.768 g of 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) as a light absorber were weighed into a brown glass bottle and stirred. The resulting photocurable composition was used to prepare a sample for evaluation using the above-mentioned sample preparation method (2b) and evaluated. The evaluation results are shown in Table 5.

[0079] (Comparative Examples 14 to 23) The photocurable material was weighed out in the proportions shown in Table 6 using the method described in Example 11, and 1.0 wt % of Omnirad 184 was weighed out as a polymerization initiator relative to the photocurable material. The mixture was then placed in a brown bottle and stirred. Samples were prepared from the resulting photocurable compositions of Comparative Examples 1 to 10 using the evaluation sample preparation method (2a) and evaluated. The evaluation results are shown in Table 6.

[0080] [Table 5]

[0081] [Table 6]

[0082] The symbols and material names in Tables 5 and 6 represent the materials listed below, and "-" indicates that the material is not used. Isobornyl: Isobornyl acrylate (molecular weight 208) manufactured by Tokyo Chemical Industry Co., Ltd. Tricyclodecane: Hitachi Chemical's dicyclopentanyl acrylate (FA-513AS molecular weight 206) 3Me cyclohexane: 3,3,5-trimethylcyclohexanol acrylate (SR420NS, molecular weight 210) manufactured by Arkema tBu cyclohexane: 4-tert-butylcyclohexanol acrylate (SR217NS, molecular weight 210) manufactured by Arkema Branched C18: Isostearyl acrylate (S-1800A, molecular weight 325) manufactured by Shin-Nakamura Chemical Co., Ltd. Branched C8: Isooctyl acrylate (SR440, molecular weight 184) manufactured by Arkema Branched C10: Isodecyl acrylate (SR395, molecular weight 212) manufactured by Arkema Linear C18 methacrylate: Shin-Nakamura Chemical Co., Ltd. isostearyl methacrylate (S-1800M, molecular weight 339) Polyethylene glycol: Ethoxylated ethylhexyl polyethylene glycol methacrylate (EH-4E, molecular weight 374) manufactured by Shin-Nakamura Chemical Co., Ltd. Diethylene glycol methacrylate: Diethylene glycol dimethacrylate (2G, molecular weight 242) manufactured by Shin-Nakamura Chemical Co., Ltd. Tricyclodecane acrylate: Tricyclodecanol acrylate (KAYARAD R-684, molecular weight 304) manufactured by Nippon Kayaku Dioxane Acrylate: 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxane-2-yl]-2,2-dimethylethyl acrylate (KAYARAD R-604, molecular weight 326) manufactured by Nippon Kayaku Co., Ltd. Neopentyl glycol: Neopentyl glycol diacrylate (A-NPG, molecular weight 212) manufactured by Shin-Nakamura Chemical Co., Ltd. Nonanediacrylate: 1,9-nonanediol diacrylate (A-NOD-N, molecular weight 268) manufactured by Shin-Nakamura Chemical Co., Ltd. A-400: Polyethylene glycol #400 diacrylate (A-400 molecular weight 523) manufactured by Shin-Nakamura Chemical Co., Ltd. Butanediol: 1,4-butanediol diacrylate (SR213, molecular weight 198) manufactured by Arkema

[0083] As described above, the photocurable composition of the present invention can be used in a wide range of applications in the field of optical three-dimensional modeling, without any particular limitations. Typical applications of the cured product of the photocurable composition of the present invention include a lost-wax casting model, a model for verifying the appearance design during the design process, a model for checking the functionality of a part, and a base model for producing a mold. In particular, the cured product of the photocurable composition of the present invention has low thermal expansion, a high elastic modulus, and heat resistance within a certain temperature range, making it suitable for use as a lost-wax casting model.

[0084] Furthermore, when a cured product is obtained using the photocurable composition of the present invention by a casting molding method, it becomes possible to provide a molded object with a precision that cannot be achieved in the field of optical three-dimensional modeling using a photocurable material. The method for molding the cured product in this case involves pouring the photocurable composition of the present invention into a mold, placing a transparent substrate of a size that matches the mold, and irradiating the mold with active energy rays through the transparent substrate. If poor transfer of the mold shape occurs due to the curing shrinkage of the material composition, the photocurable composition may be pressurized while irradiating the active energy rays. Furthermore, as with optical three-dimensional modeling, the desired molded object may be obtained by repeatedly injecting the photocurable composition into a mold and curing it little by little. [Industrial Applicability]

[0085] The photocurable composition and cured product of the present invention can be used as a photocurable material for evaporative models, which has a high elastic modulus, low thermal expansion, and heat resistance over a certain temperature range compared to conventional materials for optical three-dimensional modeling used in evaporative models, and does not contain a photoacid generator used in epoxy materials, etc. Therefore, they can be used to produce highly accurate castings with few voids in the lost-wax casting method.

Claims

1. A photocurable composition comprising a curable material consisting of a monofunctional (meth)acrylate having a molecular weight of 150 or more and less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400, The content of the monofunctional (meth)acrylate is 80 mol % or more and 90 mol % or less of the curable material, and the monofunctional (meth)acrylate comprises a monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure and a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, the content of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is 40 mol % or more and 50 mol % or less of the curable material, The photocurable composition, wherein the alicyclic skeleton forming the three-dimensional crosslinked structure is one or more selected from the group consisting of an adamantane skeleton, a norbornane skeleton, and a dicyclopentadiene skeleton.

2. 2. The photocurable composition according to claim 1, wherein the monofunctional (meth)acrylate having an alicyclic skeleton that forms the three-dimensional crosslinked structure is one or more selected from the group consisting of isobornyl acrylate, adamantyl acrylate, and dicyclopentanyl acrylate.

3. 3. The photocurable composition according to claim 1, wherein the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond is cyclic trimethylolpropane formal (meth)acrylate.

4. the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is one or more selected from the group consisting of isobornyl acrylate, adamantyl acrylate, and dicyclopentanyl acrylate; the monofunctional (meth)acrylate containing an alicyclic structure having an ether bond is cyclic trimethylolpropane formal (meth)acrylate; The photocurable composition according to any one of claims 1 to 3, wherein the bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400 is one or more selected from diethylene glycol dimethacrylate, tricyclodecanol acrylate, 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxan-2-yl]-2,2-dimethylethyl acrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, and polyethylene glycol #200 diacrylate.

5. the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is one or more selected from the group consisting of isobornyl acrylate and adamantyl acrylate; 5. The photocurable composition according to claim 4, wherein the bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400 is one or more selected from the group consisting of tricyclodecanol acrylate and 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxan-2-yl]-2,2-dimethylethyl acrylate.

6. 6. The photocurable composition according to claim 1, wherein the bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400 has a side chain selected from a linear alkyl chain, a branched alkyl chain, an ethylene glycol chain, and a propylene glycol chain, each having 1 to 6 carbon atoms.

7. The photocurable composition according to any one of claims 1 to 6, wherein the bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400 is one or more selected from the group consisting of diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxan-2-yl]-2,2-dimethylethyl acrylate.

8. A cured product obtained by polymerization or copolymerization of the curable material in the photocurable composition according to claim 1 .

9. The cured product according to claim 8, wherein the deflection temperature under load of the cured product is 45°C or higher but lower than 60°C.

10. A method for producing a cured product, comprising polymerizing or copolymerizing the curable material in the photocurable composition according to claim 1 .

11. disposing a photocurable resin composition to a predetermined thickness; a step of irradiating the photocurable resin composition with light energy to cure it based on slice data of the three-dimensional model; Including, the photocurable resin composition contains a curable material made of a monofunctional (meth)acrylate having a molecular weight of 150 or more and less than 350 and a bifunctional (meth)acrylate having a molecular weight of 200 or more and less than 400, the content of the monofunctional (meth)acrylate is 80 mol % or more and 90 mol % or less of the curable material, the monofunctional (meth)acrylate comprises a monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure and a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, the content of the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure is 40 mol % or more and 50 mol % or less of the curable material, A method for producing an article, wherein the alicyclic skeleton forming the three-dimensional crosslinked structure is one or more selected from an adamantane skeleton, a norbornane skeleton, and a dicyclopentadiene skeleton.

12. 12. The method for manufacturing an article according to claim 11, further comprising a step of washing and / or post-curing a shaped object obtained by repeating a step of disposing the photocurable resin composition to a predetermined thickness and a step of irradiating the photocurable resin composition with light energy to cure the composition multiple times.

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