JP7762010B2 - Photocurable composition and cured product thereof - Google Patents

Description

The present invention relates to a photocurable composition and a method for producing a cured product using the composition for use in lost-wax casting.

In recent years, additive manufacturing technology, which creates three-dimensional objects from photocurable materials based on three-dimensional data, has become widely adopted, as it allows for the production of desired three-dimensional objects with good dimensional accuracy without the need to create molds or other tools.

The method of creating three-dimensional objects from photocurable materials 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.

In order to improve the defoaming of trapped bubbles in the liquid photocurable material supplied on top of the curing layer and to improve the smoothness of the liquid surface, it is desirable for the viscosity of the material used in photolithography to be as low as possible. Furthermore, photolithography is used to create a variety of models, including design prototypes, architectural models, and medical models, as well as loss models for obtaining castings. Depending on the characteristics required for each of these applications, energy beam-curable resin compositions are being developed by improving the type and formulation of resin materials, as well as adding functional fillers and pigments.

Patent Document 1 discloses a resin composition for modeling materials that can be used to obtain stereolithography products that are flexible and will not break even when bent, and a method for producing stereolithography products formed using the resin composition for modeling materials. The resin composition for modeling materials in Patent Document 1 uses a formulation that contains 20 to 90 parts by weight of a monofunctional monomer containing a cyclic ether skeleton, 5 or more parts by weight of a polyfunctional oligomer, and either no polyfunctional monomer or 15 or less parts by weight of the polyfunctional monomer, per 100 parts by weight of the curable resin composition.

Patent Document 2 provides a photocurable composition that exhibits excellent flexural strength and flexural modulus, as well as flexural resistance, and excellent tensile strength and elongation. Specifically, the polymerizable compounds selected for the photocurable composition include at least one di(meth)acrylic monomer having a weight-average molecular weight of 400 to 800 and no more than one di(meth)acrylic monomer that has no hydroxyl or carboxyl groups in one molecule, two aromatic rings, and two (meth)acryloyloxy groups, and at least one (meth)acrylic monomer having a weight-average molecular weight of 130 to 350 and no more than one (meth)acrylic monomer that has at least one ring structure and one (meth)acryloyloxy group in one molecule.

However, while Patent Document 1 aims to produce a flexible object, there is a concern that when a large object is produced or depending on the shape of the object, it may not be able to withstand its own weight and may become distorted. Furthermore, Patent Document 2 uses a monomer with a defined molecular weight to provide a photocurable composition that has 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 deteriorate when used as an elimination model.

International Publication No. 2017/222025 International Publication No. 2018/181833

The present invention was made in consideration of the background art described above. It is an object of the present invention to provide a photocurable composition that produces a shaped object with low thermal expansion, a high elastic modulus, and heat resistance over a certain temperature range, and that does not contain a photoacid generator.

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 with 15 to 20 carbon atoms.

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.

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.

The present invention provides 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 enables high mechanical properties and a low ash content due to the absence of a photoacid generator, which were not possible with material formulations for photocurable elimination models that can be used in conventional optical 3D modeling. This eliminates the need for the conventional process of creating a mold and then producing an elimination model by injection molding, and makes it possible to quickly produce castings with high accuracy and few defects such as casting cavities from elimination models produced directly using optical 3D modeling.

FIG. 1 is a diagram illustrating a configuration example of a modeling apparatus using a free surface method.

(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 composed 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 is composed 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.

The curable material is not particularly limited as long as it is a curable material 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 main skeleton moieties necessary for expressing mechanical properties such as alicyclic skeletons, and 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.

In the photocurable composition of this embodiment, the content of 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 that has a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range.

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 having small 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.

There are no particular limitations on the monofunctional (meth)acrylate containing an alicyclic structure with an ether bond, 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 with an ether bond include monofunctional (meth)acrylates containing a dioxane skeleton, a tetrahydropyran skeleton, a tetrahydrofuran skeleton, etc. By including a monofunctional (meth)acrylate containing an alicyclic structure with an ether bond in the photocurable composition of this embodiment, the structure derived from the monofunctional (meth)acrylate with an alicyclic skeleton ensures a high elastic modulus, low thermal expansion, and heat resistance over a certain temperature range in the cured product, while the structure derived from the monofunctional (meth)acrylate containing an alicyclic structure with an ether bond enables improved interlayer adhesion when molded by photolithography. This improves not only the flexural modulus of the cured product but also its flexural strength. Specific examples include monofunctional (meth)acrylates containing an alicyclic structure with 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 with an ether bond. To provide a cured product as an elimination model with small thermal expansion, a higher elastic modulus, and heat resistance over a certain temperature range, it is preferable that the monofunctional (meth)acrylate containing an alicyclic structure with an ether bond be tetrahydro-2H-pyran-2-yl acrylate or cyclic trimethylolpropane formal (meth)acrylate.

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 composition 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 composition is exposed in the mold baking process. This may also result in reduced adhesion between layers 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% or more and 80 mol% or less of the curable material. Furthermore, in order to provide a cured product that has low thermal expansion, a higher elastic modulus, heat resistance over 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 be 40 mol% or more and 50 mol% or less of the curable material.

There are no particular limitations on the bifunctional (meth)acrylate with a molecular weight of 200 or more but less than 400, as long as it can provide a cured product as a loss model with low thermal expansion, high elastic modulus, and heat resistance over a certain temperature range in the photocurable composition. In bifunctional (meth)acrylates with a molecular weight of 200 or more but less than 400, if the linear molecular structure to which the (meth)acryloyl groups are bonded accounts for a large volume proportion in the cured product, there are concerns about a decrease in the elastic modulus of the cured product and an increase in the 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, raising concerns about reduced polymerization reactivity due to steric hindrance, etc. Therefore, bifunctional (meth)acrylates with a molecular weight of 200 or more but less than 400 are preferably bifunctional (meth)acrylates having a side chain containing 1 to 6 carbon atoms and selected from linear alkyl chains, branched alkyl chains, ethylene glycol chains, and propylene glycol chains. Specific examples include 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 or more bifunctional (meth)acrylates having a molecular weight of 200 or more but less than 400.

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

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.

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, based on the photocurable composition. A single type of polymerization initiator can be used, or two or more types can be used in combination. The amount of polymerization initiator added to the photocurable composition can be selected appropriately depending on the light irradiation dose and additional heating temperature. It can also be adjusted depending on the target average molecular weight of the resulting polymer. Furthermore, by using it in combination with a light absorber, as described below, the critical exposure dose and penetration depth in optical 3D modeling methods can be adjusted.

The light absorber can be selected appropriately depending on the wavelength of UV light used in the optical 3D modeling method, but if inorganic materials such as inorganic fillers are used and the cured product of the photocurable composition is used as an erosion model, ash will remain when it is burned, so it is desirable to select an organic material. In addition, 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 transparency. Examples of materials other than photosensitizers and light-resistance stabilizers include organic polymer fillers, but there are no particular restrictions on them.

Polymerization inhibitors act as polymerization inhibitors during reaction and storage, and include, but are not limited to, 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 substituted phenol-based polymerization inhibitors such as 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

The amount of 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. Furthermore, only one polymerization inhibitor may be used, or two or more polymerization inhibitors may be used in combination.

Photosensitizers include benzophenone, 4,4-diethylaminobenzophenone, 1-hydroxycyclohexyl phenyl 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. Polymerization inhibitors include, but are not limited to, those listed above as polymerization inhibitors during reaction and storage. A single polymerization inhibitor may be used alone, or two or more polymerization inhibitors may be used in combination. Considering minimal coloration of the cured product, it is preferable to use a combination of hydroquinone-based polymerization inhibitors. The amount added is preferably between 0.01% and 10.00% by mass of the photocurable composition.

There are no particular restrictions on light resistance stabilizers as long as they do not significantly affect the properties of the cured product, and examples 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 no photosensitizer needs to be added. 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 optical three-dimensional modeling method. The amount added is preferably in the range of 0.01% by mass to 5.00% by mass of the photocurable composition.

The photocurable composition of this embodiment may contain other polymerizable or non-polymerizable materials that can polymerize with the photocurable composition to adjust the viscosity of the photocurable composition or to impart functionality, as long as the material provides a material for a cured product as an elimination 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 added is too small, the effect of adding the polymerizable material will not be obtained, while if the amount added is too large, the mechanical properties of the cured product will be reduced when the photocurable composition is cured. Therefore, an amount of 0.1 mol % to 10.0 mol % is preferred. There are no particular restrictions on the polymerizable material, and it can be a monofunctional or difunctional or higher (meth)acrylate compound.

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, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane di(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol, tetritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)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, methoxyditripropylene glycol (meth)acrylate, Tricyclodecane (meth)acrylate, isobornyl (meth)acrylate, dicyclopentadieneoxyethyl (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-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, dioxane Examples include, but are not limited to, 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, and multiple compounds may be used simultaneously.

There are no particular restrictions on the non-polymerizable material, but considering adhesion and compatibility when forming a cured product as a lost model using optical 3D modeling, alcohol-based (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.

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 achieve uniform mixing 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.

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 polymerizable functional groups contained in the monofunctional (meth)acrylate having an alicyclic skeleton that forms a three-dimensional crosslinked structure, the monofunctional (meth)acrylate having an alicyclic structure with an ether bond, and the bifunctional (meth)acrylate are each polymerized.

Conventionally known optical three-dimensional modeling methods and devices can be used to perform optical three-dimensional modeling using the photocurable composition of this embodiment. Preferably, the method involves repeatedly repeating the process of selectively irradiating the photocurable composition with active energy rays to form a cured layer having the desired pattern, ultimately obtaining the desired three-dimensional object.

Examples of active energy rays (also called light energy) include ultraviolet rays, electron beams, X-rays, radiation, and high-frequency waves. Among these, ultraviolet rays with a wavelength of 300 to 430 nm are preferred from an economical standpoint, and light sources for 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.

When irradiating a modeling surface made of a photocurable composition with active energy rays to form each cured resin layer having a predetermined geometric pattern, the cured resin layer may be formed by a pointillist or line drawing method using active energy rays focused into a point shape, such as laser light. Alternatively, a modeling method may be used in which the modeling surface is irradiated with active energy rays in a planar manner through a planar drawing mask formed by arranging multiple microscopic optical shutters, such as liquid crystal shutters or digital micromirror shutters (DMDs), to form the cured resin layer.

As a representative example of a preferred stereolithography method, the free surface method will be described. Figure 1 shows an example of the configuration of a modeling device 100 using the free surface method. The modeling device 100 has a tank 11 that contains a liquid curable resin composition 10. Inside the tank 11, a modeling stage 12 is provided that can be driven vertically by a drive shaft 13. An active energy beam 15 for curing the curable resin composition 10 is emitted from a light source 14 and irradiates 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 Figure 1, the scanning range is indicated by a thick dashed line.

The depth (thickness) d from the surface of the photocurable resin composition 10 that is 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 being formed). The thickness d is achieved by the control unit 18 controlling the drive amount of the drive shaft 13.

First, the control unit 18 controls the drive shaft 13 based on the settings, and a 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 with 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, forming 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.

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 Figure 1, with the stage 12 of the modeling apparatus 100 positioned to raise the model 17 above the liquid surface, and a light irradiation means positioned below the vat 11. A typical modeling example using the regulated liquid level method is as follows: First, a support stage that can be raised and lowered is set so that its support surface is a predetermined distance from the bottom 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 of the vat. Next, a laser light source or projector selectively irradiates light from the bottom of the vat containing the curable resin composition onto the curable resin composition between the stage support surface and the bottom of the vat in accordance with slice data. The light irradiation cures the curable resin composition between the stage support surface and the bottom of the vat, forming a solid cured layer. The support stage is then raised, and the cured layer is peeled off from the bottom of the vat.

Next, the height of the support stage is adjusted so that a predetermined distance is maintained between the cured layer formed on the support stage and the bottom of the vat. 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 shaped 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, post-processing can be carried out as necessary to obtain the desired article.

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.

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 comprises 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.

The photocurable composition of this embodiment is not particularly limited as long as it is a composition comprising 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. However, as the molecular weight decreases, the volatility of the material increases, leading to formulation changes during storage, so a molecular weight of 150 or more is preferred. 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 main skeleton moieties necessary for expressing mechanical properties such as alicyclic skeletons, and resulting in reduced mechanical properties as a material for elimination models. Therefore, it is preferred that the molecular weight be less than 350 for monofunctional (meth)acrylates and less than 400 for bifunctional (meth)acrylates.

In the photocurable composition of this embodiment, there are no particular restrictions on the content of the monofunctional (meth)acrylate, but in order to provide a material formulation for a disappearance model that has a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range, it is preferable for the content to be 50 mol% or more and 95 mol% or less of the curable material. More preferably, a content of 60 mol% or more and 75 mol% or less of the curable material can be used to provide a material for a disappearance model that has a higher elastic modulus, small thermal expansion, and heat resistance over a certain temperature range.

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 over a certain temperature range. 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 it provides a material for a fading model that has a high elastic modulus, small thermal expansion, and heat resistance over a certain temperature range, it is acceptable to use one type or multiple types simultaneously.

There are no particular limitations on the monofunctional (meth)acrylate with a branched alkyl chain structure, as long as it can provide a fading model material with a high elastic modulus, low expansion, and heat resistance over a certain temperature range. As the alkyl chain length increases, heat resistance over a certain temperature range decreases and thermal expansion increases. On the other hand, as the alkyl chain length decreases, heat resistance over a certain temperature range increases. This makes it impossible to provide a fading model material with a high elastic modulus, low 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 fading model material with a high elastic modulus, low 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, low 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 with a branched alkyl chain structure include isostearyl (meth)acrylate.

There are no particular restrictions on 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, as long as it provides a material for elimination models that has a high elastic modulus, low thermal expansion, and heat resistance within 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 within the certain temperature range required for the material for elimination models may exceed that temperature range, and this may also result in reduced adhesion between layers when molded using a stereolithography method. Therefore, it is preferable that the content of the monofunctional (meth)acrylate having an alicyclic skeleton and a quaternary carbon be 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, low thermal expansion, heat resistance over a certain temperature range, and improved interlayer adhesion, it is more preferable that the content of the monofunctional (meth)acrylate having an alicyclic skeleton and also a quaternary carbon be 35 mol % or more and 55 mol % or less of the curable material.

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.

The photocurable composition may further contain additives such as photopolymerization initiators, light absorbers, polymerization inhibitors, photosensitizers, light stabilizers, heat stabilizers, antioxidants, release agents, and anti-fungal 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 that may be added as needed can be the same as those described in the first embodiment.

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 achieve uniform mixing by stirring alone, the composition may be prepared by heating and stirring or by diluting with a solvent and then removing the solvent.

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 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, 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 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 having 15 to 20 carbon atoms, and the polymerizable functional groups of the curable materials in the photocurable composition are copolymerized.

The method for optical three-dimensional modeling using the photocurable composition of this embodiment can use any of the conventionally known optical three-dimensional modeling methods and devices described in the first embodiment. Preferably, the photocurable composition is selectively irradiated with active energy rays to form a cured layer having the desired pattern, and then an uncured liquid photocurable resin composition is placed on this cured layer, and similarly irradiated with active energy rays to form a new cured layer continuous with the cured layer. This lamination process is repeated to finally obtain the desired three-dimensional object.

The active energy rays suitable for shaping, the method of applying the active energy rays, the shaping method, etc. are the same as those in the first embodiment.

The present invention will be explained in more detail below using examples, but the present invention is not limited to the examples described below as long as they do not depart from the gist of the invention.

Example 1
10.5 g of isobornyl acrylate (manufactured by 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 having an ether bond (trade name: Sartomer SR531, manufactured by Arkema), 4.0 g of a bifunctional (meth)acrylate having a molecular weight of 200 or more but less than 400 (trade name: KAYARAD R-604, manufactured by Nippon Kayaku), and 0.24 g of a polymerization initiator (trade name: Omnirad 184, manufactured by IGM Resins B.V.) were weighed into a brown glass bottle and stirred. Using the obtained photocurable composition, an evaluation sample was prepared and evaluated according to the following evaluation sample preparation method (2a). The evaluation results are shown in Table 3.

(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 following evaluation sample preparation method (2a) and evaluated. The evaluation results are shown in Table 3.

Example 10
A photocurable composition was obtained in the same manner as in Example 1, except that a monofunctional (meth)acrylate having an alicyclic skeleton, a monofunctional (meth)acrylate containing an alicyclic structure having an ether bond, and a 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, 1.92 g of a polymerization initiator (trade name: Omnirad TPO, manufactured by IGM Resins B.V.) 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.) were used as a light absorber. Using the obtained photocurable composition, an evaluation sample was prepared and evaluated according to the evaluation sample preparation method (2b) described below. The evaluation results are shown in Table 3.

(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 following evaluation sample preparation method (2a) and evaluated. The evaluation results are shown in Table 4.

(Preparation of evaluation samples and evaluation method)
(1) Evaluation Method of 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, 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.

Deflection temperature under load A: 50°C or higher and lower than 60°C B: 45°C or higher and lower than 50°C C: Lower than 45°C or 60°C or higher Flexural modulus A: 2.5 GPa or higher B: 2.0 GPa or higher and lower than 2.5 GPa C: Lower than 2.0 GPa Flexural strength A: 90 MPa or higher B: 60 MPa or higher and lower than 90 MPa C: Lower than 60 MPa

The linear expansion coefficient was measured using a thermal analysis/thermal measurement device (product name: TMA-Q400, manufactured by TA Instrument). A cube with a side of approximately 5 mm was cut out as a sample and measured at a temperature increase rate of 10°C/min. The linear expansion coefficient in the range of 20°C to 40°C was calculated and evaluated according to the following criteria.
A: Less than 100 ppm B: 100 ppm or more but less than 130 ppm C: 130 ppm or more

(2a) Method for Preparing a Cast-Molded Product Evaluation Sample: A 4 mm x 10 mm x 80 mm framed mold was placed on a quartz plate coated with a release agent. The photocurable composition was poured into the mold and sandwiched between the quartz plates coated with a release agent. The mold was irradiated with 10 mW of UV light (evaluated with a 365 nm sensor manufactured by Ushio) for 120 seconds, a total of three times on the front, front, and back surfaces. The rectangular prism-shaped molded product was then released from the mold to obtain an evaluation sample. The obtained evaluation sample was heat-treated at 50°C for 1 hour and then at 80°C for 1 hour to obtain an evaluation sample for the cast-molded product.

(2b) Method for producing evaluation samples by optical stereolithography A 4 mm x 10 mm x 80 mm prism was fabricated using a DWS DIGITALWAX020X. The laser scanning speed was 2500 mm/sec, the laser scanning interval was 60 μm, and the edge was cut once to obtain a shaped object. The obtained evaluation sample was then washed with 2-propanol and then subjected to secondary curing by irradiating it with 405 nm light at 60 °C for 60 minutes using FormCure manufactured by Formlabs. The sample was then heat-treated at 50 °C for 1 hour and then further heat-treated at 100 °C for 1 hour to obtain an evaluation sample.

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 (trade name: KAYARAD R-684, manufactured by Nippon Kayaku Co., Ltd., 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)

If the evaluation result for deflection temperature under load, flexural modulus, flexural strength, or linear expansion coefficient is C, it is undesirable as a material for fading models, as it increases concerns about shape maintenance and mold cracking. Preferably, the evaluation result is A or B.

(Procedure for preparing and evaluating samples for evaluation)
(1) Preparation of Photocurable Compositions 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.

(2) Evaluation Method of 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 linear expansion coefficient were evaluated according to the same criteria as in the first embodiment.

(2a) Method for Producing Evaluation Samples of Cast-Molded Objects Evaluation samples of cast-molded objects were also produced in the same manner as in the first embodiment.

(2b) Method for Producing Evaluation Samples by Optical 3D Fabrication Evaluation samples were also produced by optical 3D fabrication in the same manner as in the first embodiment.

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 also a quaternary carbon, 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 B.V. as a polymerization initiator were weighed into a brown glass bottle and stirred. A sample was prepared from the obtained photocurable composition using the evaluation sample preparation method (2a) and evaluated. The evaluation results are shown in Table 5.

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

(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, 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 or more but less than 400, 1.92 g of Omnirad TPO manufactured by IGM Resins B.V. 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. A sample was prepared from the resulting photocurable composition using the evaluation sample preparation method (2b) and evaluated. The evaluation results are shown in Table 5.

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

The symbols and material names in Tables 5 and 6 represent the materials listed below, and "-" indicates that the material was not used.
Isobornyl: Isobornyl acrylate (molecular weight 208) manufactured by Tokyo Chemical Industry Co., Ltd.
Tricyclodecane: dicyclopentanyl acrylate (FA-513AS) manufactured by Hitachi Chemical
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: isostearyl methacrylate (S-1800M, molecular weight 339) manufactured by Shin-Nakamura Chemical Co., Ltd.
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.
Nonanediol diacrylate: 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

As explained 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, and is not limited in any way. Typical applications of the cured product of the photocurable composition of the present invention include lost models used in lost-wax casting, models for verifying the appearance design during the design process, models for checking the functionality of parts, and base models for creating molds. In particular, the cured product of the photocurable composition of the present invention has low thermal expansion, a high elastic modulus, and heat resistance over a certain temperature range, making it ideal for use as lost-wax models used in lost-wax casting.

Furthermore, when a cured product is obtained using the photocurable composition of the present invention through casting molding, it becomes possible to provide a molded object with a precision that is not possible 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 the appropriate size for the mold on top of it, and irradiating it with active energy rays through the transparent substrate. If poor transfer of the mold shape occurs due to shrinkage of the material composition upon curing, the photocurable composition may be pressurized while irradiating it with 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.

The photocurable composition and cured product of the present invention have a higher elastic modulus, lower thermal expansion, and heat resistance over a certain temperature range compared to conventional optical three-dimensional modeling materials for efflorescent models, and can be used as a photocurable efflorescent modeling material that does not contain the photoacid generators used in epoxy materials, etc. Therefore, they can be used in the lost-wax casting method to produce castings with high precision and few voids.

Claims (12)

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. 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. 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. 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. 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. 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. 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. A cured product obtained by polymerization or copolymerization of the curable material in the photocurable composition according to claim 1 . 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. A method for producing a cured product, comprising polymerizing or copolymerizing the curable material in the photocurable composition according to claim 1 . 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. 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.