Curing type composition, method for manufacturing three-dimensional molded objects, apparatus for manufacturing three-dimensional molded objects, and artificial tooth molded objects

Abstract

To provide a curable composition that does not contain titanium dioxide, is highly safe, can be ejected using inkjet technology, and has high strength and whiteness after curing. [Solution] A curable composition comprising a radical polymerizable monomer and a hard solid component having a volume average particle diameter of 10 nm to 1,000 nm, wherein the content of the hard solid component is 3% to 40% by volume, and the difference (n1-n2) between the refractive index (n1) of the cured product of the components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more.

Description

Technical Field

[0001] The present invention relates to a curable composition, a method for producing a three-dimensional shaped article, an apparatus for producing a three-dimensional shaped article, and an artificial tooth shaped article. Background Art

[0002] As a technique for shaping three-dimensional solid objects, a technique called Additive Manufacturing (AM) is known. This technique is a method for shaping a three-dimensional object by calculating the cross-sectional shape obtained by slicing an object thinly in the lamination direction, and then forming and laminating each layer according to the calculated cross-sectional shape. In recent years, among additive manufacturing technologies, the material jetting method, which forms three-dimensional objects by discharging a curable composition to required positions using an inkjet head and curing the discharged curable composition by irradiation with active energy using a light irradiation device or the like, has attracted attention.

[0003] The material jetting method is mainly used for prototyping purposes, and cured products are required to have various properties such as strength, ductility, impact resistance, and heat resistance. As a method for improving these properties, attempts have been made to add inorganic fillers to curable compositions.

[0004] Another feature of the material jetting method is that coloring can be achieved by using color ink. Titanium oxide has been widely used as a coloring material for whitening inks. However, titanium oxide has recently been classified into Carcinogenicity Category 2 in Europe (applicable from September 2021), and safety regulations have become stricter. Accordingly, there is a demand for titanium oxide-free white inks with low safety concerns.

[0005] Hitherto, for the purpose of producing tough shaped articles, a photocurable resin composition containing a reactive monomer, a reactive oligomer, a photopolymerization initiator, and ceramic particles has been proposed (see, for example, Patent Document 1). Summary of the Invention [Problems that the invention aims to solve]

[0006] The present invention aims to provide a curable composition that does not contain titanium dioxide, is highly safe, can be inkjet-printed, and has high strength and whiteness after curing. [Means for solving the problem]

[0007] As a means for solving the aforementioned problems, the curable composition of the present invention comprises a radical polymerizable monomer and a hard solid component having a volume-average particle diameter of 10 nm to 1,000 nm, wherein the content of the hard solid component is 3% to 40% by volume, and the absolute value of the difference (|n1-n2|) between the refractive index (n1) of the cured product of the components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a curable composition that does not contain titanium dioxide, is highly safe, can be ejected using an inkjet printer, and has high strength and whiteness after curing. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing an example of a manufacturing apparatus for three-dimensional objects according to the present invention. [Figure 2] Figure 2 shows an example of a method for preparing a sample for measuring total light transmittance in the embodiment. [Modes for carrying out the invention]

[0010] (Curable composition) The curable composition of the present invention comprises a radical polymerizable monomer and a hard solid component having a volume-average particle diameter of 10 nm to 1,000 nm, wherein the content of the hard solid component is 3% to 40% by volume, and the absolute difference (|n1-n2|) between the refractive index (n1) of the cured product of the components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more. Furthermore, it may optionally contain other components such as polymerization initiators, surfactants, polymerization inhibitors, colorants, and dispersants. A "curable composition" is a composition that hardens and forms a cured product when irradiated with active energy rays or heated. Examples include active energy ray curable compositions and thermosetting compositions. The curable composition can be preferably used exclusively with an inkjet method, and is preferably an active energy ray curable composition for inkjet use or a thermosetting composition for inkjet use, with an active energy ray curable composition for inkjet use being more preferable. In this invention, "curing" refers to the formation of a polymer, but is not limited to solidification; it also includes cases where viscosity increases or both solidification and viscosity increases occur. Furthermore, while "solidified material (hardened material)" refers to polymers, it is not limited to solids; it also includes thickeners and mixtures of solids and thickeners.

[0011] The inventors of this invention investigated the following problems in the prior art and obtained the following findings. Conventional technologies have used titanium dioxide as a white coloring agent, but with increasingly stringent safety regulations, there is a demand for white inks that do not use titanium dioxide, which has high opacity, and that pose fewer safety concerns. However, the inventors have found that without using titanium dioxide, it is difficult to ensure shielding properties and whiteness, and that conventional photocurable resin compositions containing ceramic particles (Japanese Patent Publication No. 6774659) have the problem of not being able to obtain sufficient whiteness. Furthermore, when hard solid components are included in active energy ray curable compositions, the viscosity increases, which can make it difficult to eject them using an inkjet method. This presents a problem in that it is difficult to ensure whiteness and hardness after curing while also making it possible to eject them using an inkjet method. This invention is based on the discovery of the aforementioned problems of the prior art.

[0012] [Absolute value of refractive index difference] The absolute value of the difference (|n1-n2|) between the refractive index (n1) of the cured product of components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more, preferably 0.05 or more, and more preferably 0.07 or more. The curable composition of the present invention, when the absolute value of the refractive index difference is 0.04 or more, can ensure whiteness even without containing titanium dioxide, which has high shielding properties, and can be obtained as a curable composition that is highly safe, inkjet-compatible, and has high strength and whiteness after curing. The aforementioned refractive index refers to the refractive index n25D measured at 25°C using Method B with an Abbe refractometer as described in JIS K 7142, on the D line (wavelength 589.3 nm light) of a sodium lamp. For example, it can be measured using an Abbe refractometer NAR-1T (manufactured by Atago Co., Ltd.) on the D line (589.3 nm) of a light source lamp.

[0013] The refractive index (n1) of the cured product of components other than the aforementioned hard solid component can be measured by the following procedure. First, a mixture of components other than the hard solid component, or a cured product is prepared by curing the liquid component obtained by removing the hard solid component from the curable composition. Next, the cured product is scraped with waterproof abrasive paper #400 or a metal file, and the refractive index of the resulting powder of the cured product of components other than the hard solid component is measured. Specifically, in accordance with Method B of JIS K 7142, which states that "for powders, pellets and granular materials, prepare an amount of sample sufficient for at least 5 measurements, perform 5 measurements, then calculate the average value and obtain it to four significant figures", the average refractive index of a cured product formed from components other than the hard solid component is defined as n1.

[0014] The refractive index of the hard solid component n2 can be measured either by using the hard solid component directly or by separating it from the curable composition before measurement. Specifically, in accordance with Method B of JIS K 7142, which states that "for powders, pellets and granular materials, prepare an amount of sample sufficient for at least 5 measurements, perform 5 measurements, then calculate the average value and obtain it to four significant figures", the average refractive index calculated for the hard solid component is defined as n2, the refractive index of the hard solid component.

[0015] It is also possible to identify the hard solid component and components other than the hard solid component from a cured product obtained by curing the curable composition, a three-dimensional shaped article, or an artificial tooth shaped article. Specifically, the hard solid component and other components in the curable composition can be identified by pyrolysis GC-MS (gas chromatography-mass spectrometry), FT-IR (Fourier transform infrared spectroscopy), micro-Raman spectroscopy, various NMR (nuclear magnetic resonance analysis), TOF-SIMS (time-of-flight secondary ion mass spectrometry), and other methods. Through the above procedure, n1, the refractive index of the cured product of components other than the hard solid component, and n2, the refractive index of the hard solid component, can be obtained.

[0016] <Hard solid component> The hard solid component has a volume-average particle diameter of 10 nm or more and 1000 nm or less. The hard solid component can improve the elastic modulus, strength, impact resistance, and other properties of a cured product of the curable composition. Here, the term "hard" refers to the property of being difficult to deform under external stress. Whether a material is hard or not can be determined by a person skilled in the art based on criteria known in the art, and examples of such criteria include Vickers hardness and elastic modulus. In a preferred embodiment, the elastic modulus of the hard solid material is 4 GPa or more, more preferably 5 GPa or more. The elastic modulus can be determined, for example, in accordance with JIS K 7161, JIS K 7171, ISO 14577 and the like.

[0017] Examples of the hard solid component include glass, silica, alumina, zirconia, calcium carbonate, wollastonite, xonotlite, gypsum fiber, aluminum borate, aramid fiber, carbon fiber, glass fiber, talc, mica, glass flakes, polyoxybenzoyl whiskers, and various resins. Among these, silica, alumina, zirconia, and calcium carbonate are preferred from the viewpoint of excellent whiteness, and silica is more preferred. The "solid component" refers to a component that can maintain a solid state in a curable composition. Further, the solid component is preferably in the form of particles in the curable composition under a normal temperature and normal pressure environment. Furthermore, the solid component is preferably in a dispersed state in the curable composition.

[0018] The content of the hard solid component is 3% by volume or more and 40% by volume or less based on the total volume of the composition, preferably 5% by volume or more and 30% by volume or less, and more preferably 10% by volume or more and 30% by volume or less. When the content of the hard solid component is 3% by volume or more, sufficient shielding properties can be obtained, high whiteness after curing can be obtained, and high hardness after curing can be obtained. When the content of the hard solid component is 40% by volume or less, the viscosity of the curable composition does not become too high, a curable composition suitable for inkjet ejection can be obtained, a decrease in the bonding strength in the matrix resin after curing of the curable composition can be suppressed, and as a result, the brittleness of the cured product can be suppressed. Furthermore, when the content of the hard solid component is 5% by volume or more, better shielding properties, whiteness, and hardness can be obtained in the cured product, and when it is 30% by volume or less, more stable inkjet ejection properties and hardness of the cured product can be obtained. It is known that the viscosity of a composition increases as the solid component content increases, but curable compositions used for ejection by inkjet are generally preferred to have low viscosity. Furthermore, matrix resin refers to the cured resin surrounding the hard solid component in a cured product obtained by curing a curable composition.

[0019] The shape of the hard solid component is not particularly limited and can be appropriately selected depending on the purpose. It may be spherical, rod-shaped, or irregularly shaped, and may also be hollow particles, porous particles, core-shell structure particles, etc. Among these, spherical particles are preferred in terms of dispersibility and inkjet ejection properties. The term "spherical" as used above is not limited to a perfect sphere, but may include shapes such as ellipsoids or polyhedra. While not limited to these, for example, a particle where the longest diameter (major axis) from the center point to the particle's outer diameter is approximately twice the length of the shortest diameter (minor axis) is included in the definition of "spherical" in this invention. The ratio of the minor axis to the major axis is preferably 1:1 to 1:5, and more preferably 1:1 to 1:2.

[0020] The volume-average particle size of the hard solid component is 10 nm to 1,000 nm, preferably 100 nm to 500 nm, more preferably 180 nm to 500 nm, and even more preferably 180 nm to 300 nm. If the volume-average particle size of the hard solid component is 10 nm or more, the viscosity increase due to the increase in the surface area of ​​the solid component can be suppressed, thereby improving the ejection stability by the inkjet method and obtaining sufficient shielding and whiteness. If the volume-average particle size of the hard solid component is 1,000 nm or less, the ejection stability by the inkjet method can be improved. Furthermore, if the volume-average particle size of the hard solid component is 100 nm or more and 500 nm or less, more stable inkjet ejection, and better shielding, whiteness, and hardness can be obtained in the cured product. Moreover, considering the dispersion stability of the solid component in the curable composition, 300 nm or less is preferable. The volume-average particle size and particle size distribution can be measured, for example, using a particle size analyzer (Microtrac MODEL UPA9340, manufactured by Nikkiso Co., Ltd.).

[0021] -Surface modification- Among the hard solid components mentioned above, it is preferable to use hard solid components having hydroxyl groups on their surface, such as glass, silica, and alumina, that have been surface-modified using a silane coupling agent. Among these, silica surface-modified with a silane coupling agent is preferred. The silane coupling agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include vinyl methoxysilane, vinyl ethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and styryl p-Styryltrimethoxysilane, 3-Methacryloxypropylmethyldimethoxysilane, 3-Methacryloxypropyltrimethoxysilane, 3-Methacryloxypropylmethyldiethoxysilane, 3-Methacryloxypropyltriethoxysilane, 3-Acryloxypropyltrimethoxysilane, N-2-(Aminoethyl)-3-Aminopropylmethyldimethoxysilane, N-2-(Aminoethyl)-3-Aminopropylmethyldimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropyltriethoxysilane, 3-Triethoxy Examples include silyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, hydrochloride salt of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, and 3-trimethoxysilylpropyl succinic anhydride. These may be used individually or in combination of two or more. Among these, silane coupling agents having an unsaturated double bond, such as vinylmethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-acryloxypropyltrimethoxysilane, are particularly preferred.

[0022] <Components other than hard solid components> The components other than the hard solid component, which is the liquid component of the curable composition, preferably include radical polymerizable monomers and radical polymerizable oligomers, and may further include other components such as polymerization initiators, surfactants, polymerization inhibitors, colorants, dispersants, organic solvents, and water as needed. In this invention, the term "liquid component" refers to a component that is liquid under normal temperature and pressure conditions.

[0023] <<Radical Polymerizable Monomers>> By using radical polymerizable monomers as radical polymerizable compounds, the viscosity increase of the curable composition can be further suppressed. Furthermore, by using a radically polymerizable monofunctional monomer as the radically polymerizable compound, the viscosity increase of the curable composition can be further suppressed. A "radical polymerizable compound" refers to a compound that can form a polymer by radical polymerization, and is typically a monomer unit compound having one or more radical polymerizable functional groups. Examples of radical polymerizable compounds include radical polymerizable monomers such as radical polymerizable monofunctional monomers and radical polymerizable polyfunctional monomers, as well as radical polymerizable oligomers. These may be used individually or in combination of two or more. When a radical polymerizable compound is used as the polymerizable compound in the curable composition of the present invention, viscosity increases are suppressed and the polymerization rate can be improved compared to when a cationic polymerizable compound is used, making it suitable for use in inkjet systems.

[0024] Examples of the radically polymerizable monofunctional monomers include (meth)acrylic monomers, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, (meth)acryloylmorpholine, and hydroxyethyl(meth)acrylamide. These may be used individually or in combination of two or more. Among these, (meth)acrylic monomers are preferred. Examples of the (meth)acrylic monomers mentioned above include isobornyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, 3-methoxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate, and ethoxylated nonylphenol (meth)acrylate.

[0025] Examples of the radically polymerizable polyfunctional monomers include difunctional monomers and monomers with three or more functions. These may be used individually or in combination of two or more.

[0026] Examples of bifunctional, radically polymerizable polyfunctional monomers include dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, hydroxypivalate neopentyl glycol ester di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexa Examples include 1,9-nonanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol ester di(meth)acrylate, propoxylated opentyl glycol di(meth)acrylate, ethoxy-modified bisphenol A di(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, polyethylene glycol 400 di(meth)acrylate, etc. These may be used individually or in combination of two or more.

[0027] Examples of radically polymerizable polyfunctional monomers with three or more functions include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, triallyl isocyanurate, ε-caprolactone-modified dipentaerythritol tri(meth)acrylate, ε-caprolactone-modified dipentaerythritol tetra(meth)acrylate, (meth)acrylate, ε-caprolactone-modified dipentaerythritol penta(meth)acrylate, and ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate. Examples include acrylates, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hydroxypenta(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, and penta(meth)acrylate esters. These may be used individually or in combination of two or more.

[0028] The content of radical polymerizable monomers is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, relative to the total amount of the curable composition. Furthermore, it is preferably 95.0% by mass or less, and more preferably 85.0% by mass or less.

[0029] <<Radical Polymerizable Oligomer>> By using a radically polymerizable oligomer as the radically polymerizable compound, curing shrinkage of the cured product can be reduced, and the ductility and toughness of the cured product can also be improved. The radical polymerizable oligomer is preferably a monofunctional to hexafunctional oligomer, and more preferably a bifunctional to trifunctional oligomer. These may be used individually or in combination of two or more. As radical polymerizable oligomers, it is preferable that they have hydrogen-bonding functional groups, as this allows for interactions between side chains within the polymer and improves the toughness of the cured product. From the viewpoint of balancing viscosity and hydrogen bonding, radical polymerizable oligomers having urethane groups are more preferable. Examples of hydrogen-bonding functional groups include urea groups, urethane groups, amide groups, hydroxyl groups, and carboxylic acid groups. Furthermore, as radical polymerizable oligomers having urethane groups, urethane acrylate oligomers are more preferable.

[0030] Commercially available radical polymerizable oligomers can be used, such as UV-6630B (UV-curable urethane acrylate oligomer, molecular weight: 3000, number of polymerizable functional groups: 2, manufactured by Nippon Synthetic Chemical Co., Ltd.) and CN983NS (aliphatic urethane acrylate oligomer, number of polymerizable functional groups: 2, manufactured by Sartomer). These may be used individually or in combination of two or more.

[0031] Examples of radical polymerizable compounds include acrylic monomers, methacrylic monomers, and vinyl carboxylate monomers, as described above, but it is preferable to use acrylic monomers. Acrylic monomers can suppress the increase in viscosity of the curable composition and improve the polymerization rate, so they can be suitably used in inkjet methods. When using radically polymerizable monofunctional monomers other than acrylic monomers or epoxy monomers, it is preferable to use them in combination with acrylic monomers. Examples of epoxy monomers include bis(3,4-epoxycyclohexyl) and bisphenol A diglycidyl ether. Furthermore, when using epoxy monomers in combination with acrylic monomers, it is preferable to also use oxetane monomers.

[0032] The content of the radical polymerizable oligomer is preferably 1.0% by mass or more and 40.0% by mass or less based on the total amount of the composition. More preferably, the lower limit is 10.0% by mass or more, and the upper limit is 30.0% by mass or less.

[0033] If the liquid component contains a radical polymerizable compound other than a radical polymerizable monomer, the content of the radical polymerizable compound, including the radical polymerizable monomer, is preferably 50.0% by mass or more, more preferably 60.0% by mass or less, even more preferably 70.0% by mass or more, and particularly preferably 80.0% by mass or more, based on the total amount of the composition. Furthermore, it is preferably 95.0% by mass or less, and more preferably 90.0% by mass or less.

[0034] <<Polymerization initiator>> As the polymerization initiator, any substance that generates radicals upon irradiation with light (particularly ultraviolet light with a wavelength of 220 nm to 400 nm) can be used. One substance may be used alone, or two or more substances may be used in combination. Examples of polymerization initiators include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p,p'-chlorobenzophenone, p,p-bisdiethylaminobenzophenone, Michler ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, thioxanthone, 2-chlorothioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-one, 1-(4-isopropylphenyl)2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, 1-hydroxycyclohexylphenyl ketone, azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide. These may be used individually or in combination of two or more. The polymerization initiator content is preferably 0.1% by mass or more and 10.0% by mass or less, and more preferably 1.0% by mass or more and 5.0% by mass or less, relative to the total amount of the curable composition.

[0035] <Other ingredients> The aforementioned other components are not particularly limited and can be appropriately selected depending on the purpose. Examples include surfactants, polymerization inhibitors, colorants, viscosity modifiers, antioxidants, crosslinking accelerators, UV absorbers, plasticizers, preservatives, solvents, and dispersants.

[0036] <<Surfactants>> The surfactant is preferably a compound with a molecular weight of 200 to 5000, and specifically includes PEG-type nonionic surfactants [1-40 molar adducts of ethylene oxide (hereinafter abbreviated as EO) of nonylphenol, 1-40 molar adducts of EO stearate, etc.], polyhydric alcohol-type nonionic surfactants (sorbitan palmitate monoester, sorbitan stearate monoester, sorbitan stearate triester, etc.), fluorine-containing surfactants (1-50 molar adducts of perfluoroalkyl EO, perfluoroalkyl carboxylates, perfluoroalkyl betaine, etc.), and modified silicone oils [polyether-modified silicone oil, (meth)acrylate-modified silicone oil, etc.]. These may be used individually or in combination of two or more.

[0037] <<Polymerization inhibitor>> Examples of polymerization inhibitors include phenol compounds [hydroquinone, hydroquinone monomethyl ether, 2,6-di-t-butyl-p-cresol, 2,2-methylene-bis-(4-methyl-6-t-butylphenol), 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, etc.], sulfur compounds [dilaurylthiodipropionate, etc.], phosphorus compounds [triphenylphosphite, etc.], and amine compounds [phenothiazine, etc.]. These may be used individually or in combination of two or more.

[0038] <<Colorants>> The curing composition may contain a colorant, but it is preferable not to include one if the curing composition results in a white cured product. Furthermore, the aforementioned colorant refers to, for example, a dye or pigment, and as stated above, is functionally distinct from the aforementioned hard solid component. In this specification, "substantially free" of the colorant means that it is not included to such an extent that the properties of the colorant affect the curable composition, and it is preferable that the content is less than 0.1% by mass of the total mass of the curable composition.

[0039] <<Dispersant>> A dispersant is an additive that has the function of stably dispersing solid components in a curable composition by adsorbing them onto the surface of the solid components. Any known dispersant can be used as appropriate.

[0040] <<Organic solvent>> The curable composition may contain organic solvents, but it is preferable if possible that it does not. A composition that does not contain organic solvents, especially volatile organic compounds (VOC-free), will have a higher safety at the location where the composition is handled and will help prevent environmental pollution. Note that "organic solvent" refers to common non-reactive organic solvents such as ether, ketone, xylene, ethyl acetate, cyclohexanone, and toluene, and should be distinguished from polymerizable compounds. Furthermore, "does not contain" organic solvents means that they are substantially absent (for example, not present to the extent that the properties of the organic solvent affect the composition), and it is preferable that the amount is less than 0.1% by mass.

[0041] <<Water>> The curing composition may contain water, but it is preferable to omit it if possible. Furthermore, "water-free" means substantially water-free (for example, not to the extent that the properties of water affect the composition), and it is preferable that the water content is less than 1.0% by mass. Keeping the water content below a certain amount helps to suppress a decrease in curing speed, a decrease in curing strength, an increase in water absorption, and a decrease in separation from the support-forming material described later.

[0042] [Physical properties of curable compositions] [viscosity] Curable compositions suitable for use in inkjet systems are preferably low in viscosity, considering factors such as ease of discharge from the nozzle. Therefore, in one embodiment, the viscosity of the curable composition is preferably 1,000 mPa·s or less, more preferably 500 mPa·s or less, even more preferably 400 mPa·s or less, and particularly preferably 300 mPa·s or less, at a temperature of 25°C. Furthermore, from the viewpoint of ejection properties and molding accuracy, the viscosity of the curable composition is preferably 6 mPa·s or higher at a 25°C environment. During molding, the viscosity of the active energy ray curable composition can be adjusted by adjusting the temperature of the inkjet head and ink channel. The viscosity can be measured by conventional methods, such as the method described in JIS Z 8803. Alternatively, for example, the VISCOMETER TVE-22L cone-plate type rotational viscometer manufactured by Toki Sangyo Co., Ltd. can be used, with a cone rotor (1°34'×R24), a rotation speed of 50 rpm, and the temperature of the constant-temperature circulating water appropriately set within the range of 20°C to 65°C. The VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

[0043] [Safety] In terms of safety, items related to safety, such as carcinogenicity, can be evaluated by checking the Safety Data Sheet (SDS) for each component (raw material) of the curable composition.

[0044] [surface tension] Compositions that can be used for inkjet applications preferably have a surface tension in the range of 20 mN / m to 40 mN / m at a 25°C environment, considering factors such as ejection stability and molding accuracy. Therefore, in one embodiment, the curable composition preferably has a surface tension of 20 mN / m to 40 mN / m at a 25°C environment.

[0045] [Method for producing a hardened composition] There are no particular limitations on the method for producing the curable composition, and various components as described above can be appropriately selected according to the purpose. For example, radical polymerizable monomers and, if necessary, other components can be introduced into a disperser such as a ball mill, kitty mill, disc mill, pin mill, or dyno mill, dispersed and uniformly mixed, and then hard solid components can be added and mixed to prepare the composition.

[0046] (Three-dimensional sculptures, artificial teeth sculptures) The three-dimensional object of the present invention is a three-dimensional object obtained by curing the curable composition of the present invention. The aforementioned three-dimensional molded object does not contain titanium dioxide, is highly safe, and can provide a three-dimensional molded object with high strength and whiteness after curing. Furthermore, by including a hard solid component, the curing composition of the present invention can improve the mechanical properties of three-dimensional molded objects (material jetting molded objects) formed by layering cured material. The aforementioned three-dimensional molded object can be suitably used for dental materials such as artificial teeth, eyeglass frames, shoe outsoles, midsoles, grip parts such as handles, hearing aids, earphones, denture bases, prosthetics, and the like. Among these, artificial teeth molded objects are preferred.

[0047] In one embodiment, the three-dimensional molded object and the artificial tooth molded object of the present invention contain a hard solid component with a volume-average particle diameter of 10 nm or more and 1,000 nm or less. The content of the hard solid component is 3% by volume or more and 40% by volume or less. The absolute value of the difference (|n1-n2|) between the refractive index (n1) of the hardened product of components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or greater. The hard solid component is spherical particles, and 50% of the primary particles of the spherical particles are distributed spaced apart from each other. When using the artificial tooth fabrication with an average thickness of 1 mm, it is preferable that the total light transmittance is 30% or less. Regarding each component and its physical properties, the matters described in the above-mentioned curable composition can be appropriately selected.

[0048] The fact that the hard solid component consists of spherical particles, and that 50% or so of the primary particles of these spherical particles are distributed spaced apart from one another, can be confirmed by breaking the three-dimensional molded object or the artificial tooth molded object with a hammer or cutting it, and observing the cross-section with a scanning electron microscope (SEM) or transmission electron microscope (TEM) to confirm that the spherical particles are uniformly dispersed.

[0049] In this specification, "artificial tooth" refers to an artificially formed tooth used to restore the function of a natural tooth lost due to caries, trauma, periodontal disease, etc., or a laminate that is attached to the surface of a natural tooth to enhance its aesthetics. Examples of the aforementioned tooth components include inlays, onlays, crowns, and bridges. Examples of all of the aforementioned teeth include implants, dentures, and other prosthetic teeth.

[0050] [Total light transmittance] The total light transmittance of the three-dimensional molded object and the cured product of the curable composition is preferably 40% or less, and more preferably 30% or less, from the viewpoint of whiteness. The total light transmittance can be determined by preparing a test specimen of a three-dimensional molded object (cured product of a curable composition) with an average thickness of 1 mm and measuring its total light transmittance in the thickness direction.

[0051] Specifically, the total light transmittance can be measured by the following method. As shown in Figure 2, an OHP sheet is placed on a glass substrate, and a silicone mold (shape: 20 mm long, 20 mm wide, average thickness 1 mm) is pressed into contact with the OHP sheet. Next, the curing composition is filled into the silicone mold, the OHP sheet is placed over it, and a glass plate is placed on top of it. Next, using an ultraviolet irradiation device (UniJet E110Z HD_385nm, wavelength 385nm, manufactured by Ushio Inc.), an irradiation intensity of 200mW / cm² was applied through a glass plate. 2 Irradiate with ultraviolet light for 5 minutes. Next, from the opposite side from the side that was previously irradiated with ultraviolet light, irradiate with an intensity of 500 mW / cm² through a glass plate. 2The specimen is irradiated with ultraviolet light for 5 minutes. Next, the OHP sheet is peeled off, the specimen is removed from the silicone mold, and left to stand for 24 hours in an environment of 23°C and 50% relative humidity to obtain a specimen with an average thickness of 1 mm. In accordance with JIS K7361-1 / HAZE: JIS K7136, the total light transmittance (Tt) of the test specimen prepared above is measured using a DIRECT READING HAZEMETER (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

[0052] A method for measuring the total light transmittance from the three-dimensional molded object and the artificial tooth molded object is to process these molded objects to a thickness of 1 mm by a metal file or cutting process, polish both sides with waterproof abrasive paper P600 or equivalent, and then measure the total light transmittance of the processed object after polishing both sides to a glossy finish with alumina abrasive powder suspended in water and felt. Furthermore, as long as the process includes polishing both sides of the portion cut out from the three-dimensional object with waterproof abrasive paper P600 or equivalent, and then polishing both sides to a glossy finish with alumina abrasive powder suspended in water and felt, the total light transmittance can be measured even if the size of the workpiece or the measuring equipment differs.

[0053] [Bending strength] The bending strength of the three-dimensional molded object and the cured product of the curable composition is preferably 50 MPa or higher from the viewpoint of maintaining shape, preferably 80 MPa or higher when used as an artificial tooth, more preferably 100 MPa or higher from the viewpoint of durability and quality, and even more preferably 120 MPa or higher. The aforementioned bending strength can be determined by preparing a test specimen of a rectangular three-dimensional object (cured product of a hardened composition) with dimensions of 10 mm x 40 mm x 1 mm and measuring its bending strength.

[0054] Specifically, the bending strength can be measured by the following method. The curable composition is filled into a tank connected to the inkjet head (MH2810, manufactured by Ricoh Co., Ltd.) of a three-dimensional object manufacturing apparatus, and the curable composition is ejected from the inkjet head onto the substrate. Next, the curable composition ejected onto the substrate is exposed to light at a light intensity of 300 mJ / cm using an ultraviolet irradiation device (UniJet E110Z HD, wavelength 385 nm, manufactured by Ushio Inc.) 2 The curable composition on the substrate is cured by irradiation. By repeating these steps, a rectangular three-dimensional object measuring 10 mm x 40 mm x 1 mm is fabricated. For each of the resulting 10mm x 40mm x 1mm rectangular three-dimensional objects, a universal testing machine (Autograph, model AG-I, manufactured by Shimadzu Corporation) was used, along with a 1kN load cell and a three-point bending jig. The distance between the supports was set to 24mm, and the stress when the load point was displaced at a speed of 1mm / min was plotted against the amount of strain. The stress at the fracture point was defined as the maximum bending stress.

[0055] Regarding stretchability, a tensile elongation at break of 3% or more is preferred, and a tensile elongation of 8% or more is more preferred. The stretchability referred to above is the stretchability measured by a tensile test (JIS K7161, JIS K7113, ISO 527, ASTM D638, etc.). Regarding heat resistance, it is preferable that the heat deflection temperature (HDT) is 50°C or higher. Furthermore, the impact resistance is preferably such that the Izod impact strength is 20 J / m or higher, and more preferably 40 J / m or higher. The heat resistance refers to the heat resistance measured by the temperature deflection (HDT) test (JIS K7191-1, ASTM D648, etc.).

[0056] (Method for manufacturing three-dimensional objects and apparatus for manufacturing three-dimensional objects) The method for manufacturing a three-dimensional object of the present invention includes an ejection step of ejecting the curable composition of the present invention by an inkjet method, and a curing step of curing the ejected curable composition by irradiating it with active energy rays, and further includes sequentially repeating the ejection step and the curing step, and further includes other steps as necessary. The manufacturing apparatus for three-dimensional molded objects of the present invention comprises an ejection means for ejecting the curable composition of the present invention by an inkjet method, and a curing means for curing the ejected curable composition by irradiating it with active energy rays, and further comprises other means as necessary.

[0057] <Discharge process and discharge means> The aforementioned ejection step is a step of ejecting the curable composition using an inkjet method, and can be suitably carried out by the ejection means. The ejection means is a means for ejecting the curable composition using an inkjet method. The discharge step preferably involves discharging the curable composition onto a stage having a lifting function using an inkjet method. The curable composition discharged onto the stage forms a liquid film.

[0058] <Curing process and curing means> The curing step involves irradiating the discharged curable composition with active energy rays to cure it, and can be suitably carried out by the curing means. The curing means is a means of curing the discharged curable composition by irradiating it with an active energy ray. In the curing process, a liquid film made of a curable composition formed on a stage is cured by irradiating it with active energy rays.

[0059] -Activation energy rays- As the active energy ray used to cure the curable composition, light is preferred, and ultraviolet light with a wavelength of 220 nm to 400 nm is particularly preferred. In addition to ultraviolet light, any light source that can provide the energy necessary to promote the polymerization reaction of polymerizable components in the composition, such as electron beams, alpha rays, beta rays, gamma rays, and X-rays, is acceptable and not particularly limited. When a particularly high-energy light source is used, the polymerization reaction can be promoted without the use of a polymerization initiator. Furthermore, in the case of ultraviolet irradiation, there is a strong desire for mercury-free solutions from an environmental protection standpoint, and replacing mercury with GaN-based semiconductor ultraviolet light-emitting devices is extremely useful both industrially and environmentally. Moreover, ultraviolet light-emitting diodes (UV-LEDs) and ultraviolet laser diodes (UV-LDs) are small, have a long lifespan, are highly efficient, and are low-cost, making them preferred as ultraviolet light sources.

[0060] <Other processes and other means> Other processes mentioned above include, for example, a smoothing process. Other means mentioned above include, for example, smoothing means.

[0061] <<Smoothing process and smoothing means>> The smoothing step is a step of smoothing the surface of the liquid film made of the curable composition discharged in the discharge step. The smoothing step smooths out any unevenness in the liquid film or layer made of the curable composition by scraping off any excess portion of the discharged curable composition. The smoothing step is preferably carried out by the smoothing means. The smoothing means is not particularly limited and can be appropriately selected depending on the purpose; for example, a roller can be used.

[0062] In the method for manufacturing a three-dimensional object of the present invention, a three-dimensional object of a desired shape is manufactured by sequentially repeating the extrusion step and the curing step.

[0063] The following describes a method for manufacturing a three-dimensional object and an apparatus for manufacturing a three-dimensional object when the curable composition of the present invention is used as a model-forming material. However, the uses of the curable composition of the present invention are not limited to these embodiments.

[0064] Figure 1 is a schematic diagram showing an example of a manufacturing apparatus for three-dimensional objects according to the present invention. The three-dimensional object manufacturing apparatus 30 shown in Figure 1 comprises head units 31 and 32, an ultraviolet irradiation unit 33, a roller 34, a carriage 35, and a stage 37. Head unit 31 extrudes model-forming material 1. Head unit 32 extrudes support-forming material 2. The roller 34 smooths the liquid film of model-forming material 1 and support-forming material 2. The ultraviolet irradiation unit 33 irradiates the extruded model-forming material 1 and support-forming material 2 with ultraviolet light to cure them. The carriage 35 reciprocates the head units 31, 32, and other means in the X direction in Figure 1. The stage 37 moves the substrate 36 in the Z direction and the Y direction, which is the depth direction in Figure 1. Note that movement in the Y direction may be performed by the carriage 35 instead of the stage 37.

[0065] If there are multiple model-forming materials for each color, the three-dimensional object manufacturing apparatus 30 may be provided with multiple head units 31 for dispensing the model-forming material of each color. For the nozzles in the head units 31 and 32, nozzles from known inkjet printers can be suitably used.

[0066] Examples of metals that can be used for the roller 34 include SUS300 series, 400 series, 600 series, hexavalent chromium, silicon nitride, and tungsten carbide. Alternatively, any of these metals coated with fluorine or silicone may be used for the roller 34. Among these metals, SUS600 series is preferred in terms of strength and workability. When using the roller 34, the manufacturing apparatus 30 for creating three-dimensional objects lowers the stage 37 in accordance with the number of layers to maintain a constant gap between the roller 34 and the surface of the object. It is preferable that the roller 34 is located adjacent to the ultraviolet irradiation unit 33.

[0067] Furthermore, to prevent the curing type composition (ink) from drying out during periods of inactivity, the three-dimensional object manufacturing apparatus 30 may be equipped with means such as caps to block the nozzles in the head units 31 and 32. In addition, to prevent nozzle clogging during prolonged continuous use, the three-dimensional object manufacturing apparatus 30 may be equipped with a maintenance mechanism for maintaining the heads.

[0068] The following describes the process of creating a molded object (cured object) by sequentially repeating the extrusion process and the curing process in the manufacturing apparatus for three-dimensional molded objects of the present invention.

[0069] The engine of the three-dimensional object manufacturing apparatus 30 moves the carriage 35 or the stage 37 and, based on the two-dimensional data showing the bottommost cross-section of the input two-dimensional data, discharges droplets of the model-forming material 1 from the head unit 31 and droplets of the support-forming material 2 from the head unit 32. As a result, droplets of the model-forming material 1 are placed at positions corresponding to pixels showing the model section in the two-dimensional data showing the bottommost cross-section, and droplets of the support-forming material 2 are placed at positions corresponding to pixels showing the support section, forming a liquid film where adjacent droplets are in contact. When one object is to be manufactured, a liquid film with a cross-sectional shape is formed in the center of the stage 37. When multiple objects are to be manufactured, the three-dimensional object manufacturing apparatus 30 may form multiple liquid films with cross-sectional shapes on the stage 37, or it may stack liquid films on top of previously manufactured objects.

[0070] It is preferable to install heaters in the head units 31 and 32. Furthermore, it is preferable to install preheaters in the path that supplies the model forming material to the head unit 31 and the path that supplies the support forming material to the head unit 32.

[0071] In the smoothing process, the roller 34 smooths out the unevenness of the liquid film or layer made of the model-forming material and support-forming material by scraping off excess portions of the model-forming material and support-forming material discharged onto the stage 37. The smoothing process may be performed once per stack in the Z-axis direction, or once every 2 to 50 stacks. In the smoothing process, the roller 34 may be stopped, or it may be rotating at a positive or negative relative speed with respect to the direction of travel of the stage 37. The rotational speed of the roller 34 may be constant, or it may have constant acceleration and deceleration. The rotational speed of the roller 34 is preferably 50 mm / s or more and 400 mm / s or less as an absolute value of the relative speed with respect to the stage 37. If the relative speed is too low, the smoothing will be insufficient and the smoothness will be impaired. If the relative speed is too high, the apparatus will need to be larger, and vibrations may cause displacement of the discharged liquid droplets, which may result in a decrease in smoothness. In the smoothing process, it is preferable that the rotation direction of the roller 34 is opposite to the direction of travel of the head units 31 and 32.

[0072] In the curing process, the engine of the three-dimensional object manufacturing apparatus 30 moves the ultraviolet irradiation unit 33 by carriage 35 and irradiates the liquid film formed in the discharge process with ultraviolet light corresponding to the wavelength of the photopolymerization initiator contained in the model part forming material and the support part forming material. As a result, the three-dimensional object manufacturing apparatus 30 cures the liquid film and forms layers.

[0073] After the bottommost layer is formed, the engine of the three-dimensional object manufacturing apparatus 30 lowers the stage by one layer. The engine of the three-dimensional object manufacturing apparatus 30 moves the carriage 35 or the stage 37 and, based on two-dimensional image data showing the second cross-section from the bottom, discharges droplets of the model forming material 1 and droplets of the support forming material 2. The discharge method is the same as when forming the bottommost liquid film. As a result, a liquid film with the cross-sectional shape shown by the second two-dimensional data from the bottom is formed on the bottommost layer. Furthermore, the engine of the three-dimensional object manufacturing apparatus 30 moves the ultraviolet irradiation machine 33 with the carriage 35 and irradiates the liquid film with ultraviolet light, thereby curing the liquid film and forming the second layer from the bottom on the bottommost layer. The engine of the three-dimensional object manufacturing apparatus 30 uses the input two-dimensional data in order from the bottom side, and repeatedly performs liquid film formation and hardening in the same manner as described above, thereby stacking layers. The number of repetitions varies depending on the number of input two-dimensional image data, or the height and shape of the three-dimensional model. Once the molding using all the two-dimensional image data is complete, the molded object of the model part supported by the support section is obtained.

[0074] The object fabricated by the three-dimensional object manufacturing apparatus 30 has a model part and a support part. The support part is removed from the object after fabrication. There are two methods of removal: physical removal and chemical removal. In physical removal, mechanical force is applied to remove the support part. On the other hand, in chemical removal, the support part is disintegrated and removed by immersion in a solvent. There are no particular restrictions on the method of removing the support part, but chemical removal is more preferable because physical removal may damage the object. Furthermore, considering the cost, removal by immersion in water is more preferable. When removal by immersion in water is adopted, the cured material of the support part forming material is selected to be water-disintegrable.

[0075] The three-dimensional objects produced by the manufacturing method and apparatus of the present invention are biocompatible and possess high strength and hardness, as described below, making them suitable for use as dental materials such as inlays, crowns, dentures, artificial teeth, and implants.

[0076] (container) The term "container" refers to a container in which the curable composition is contained. The container containing the curable composition can be used as a cartridge or bottle, which eliminates the need to directly touch the curable composition during transport and replacement, thus preventing contamination of hands and clothing. It also prevents the contamination of the curable composition with foreign matter such as dust. The shape, size, and material of the container itself are not particularly limited and should be suitable for the application and use, but it is desirable that the material be a light-shielding material that does not transmit light, or that the container be covered with a light-shielding sheet or the like. [Examples]

[0077] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0078] <Preparation of monomer-containing solution A> According to the formulation shown in Table 1 below, 70 parts by mass of bifunctional ethoxylated bisphenol A methacrylate (trade name: NK Ester BPE-100, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) and 30 parts by mass of bifunctional triethylene glycol methacrylate (trade name: NK Ester 3G, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) were uniformly mixed. Next, 5 parts by mass of diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (trade name: Omunirad TPO, manufactured by BASF) as a photopolymerization initiator and 4-methoxyphenol (MEHQ, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade I) as a polymerization inhibitor were added and uniformly mixed to prepare monomer formulation A. The unit of measurement for the formulations in Table 1 is "parts by mass".

[0079] <Preparation of monomer formulations B-D> Monomer formulations B to D were prepared according to the formulations shown in Table 1 below, using the same preparation procedure as for monomer formulation A.

[0080] The details of the materials used in Table 1 are as follows. • BPE-100: Bifunctional ethoxylated bisphenol A methacrylate, trade name: NK ester BPE-100, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. • UDMA: Urethane acrylate methacrylate resin, product number: 755885, manufactured by Sigma-Aldrich. • 3G: Bifunctional triethylene glycol methacrylate, product name: NK Ester 3G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. • MMA: Methyl methacrylate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Special Grade. (Polymerization initiator) • TPO: Omnirad TPO, made by BASF (Polymerization inhibitor) MEHQ: 4-Methoxyphenol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1.

[0081] [Table 1]

[0082] (Example 1) <Preparation of hardened composition> 90 parts by mass of monomer formulation A were mixed with 10 parts by mass of a hard solid component (AdmaFine K180SM-C5, average particle size 180 nm, manufactured by Admatec Co., Ltd.) and mixed uniformly. Next, the mixture was passed through a filter (product name: CCP-FX-C1B, manufactured by ADVANTEC, average pore size: 3 μm) to obtain the curable composition of Example 1.

[0083] (Examples 2-12) The curable compositions of Examples 2-8 were prepared according to the formulations shown in Tables 2-3 below, using the same preparation procedure as in Example 1. The units for the formulations in Tables 2-3 are "parts by mass".

[0084] (Comparative Example 1) <Preparation of titanium oxide mill base> As a comparatively hard solid component, 50 parts of JR-806 (titanium dioxide with an average particle size of 270 nm, silica content: 3% by mass, alumina content: 1% by mass, manufactured by Teika Co., Ltd.), 2.5 parts of a dispersant (Solspers 24000GR, manufactured by Abyssia), 7.5 parts of Aronics M5700 (manufactured by Toagosei Co., Ltd.), 35.2 parts of ethylene oxide-added 1,6-hexanediol diacrylate, and 4.8 parts of 3-methoxybutyl acrylate were stirred and mixed in a stirrer for 1 hour, and then treated in a bead mill for 4 hours to prepare a titanium dioxide mill base.

[0085] A curable composition of Comparative Example 1 was prepared using the same manufacturing procedure as in Example 1, according to the formulation shown in Table 4 below. The units for the formulations in Table 4 are "parts by mass".

[0086] (Comparative Examples 2-4) The curable compositions of Comparative Examples 1 to 4 were prepared using the same manufacturing procedure as in Example 1, according to the formulations shown in Table 4 below. The units for the formulations in Table 4 are "parts by mass".

[0087] For the obtained curable compositions, the following parameters were measured: "refractive index (Rm) of the cured monomer mixture," "refractive index (Rs) of the hard solid component," "refractive index difference (Rm-Rs)," "viscosity," and "safety." For the cured products prepared by curing the curable compositions, "total light transmittance" and "flexural strength" were also measured. The results are shown in Tables 2-4.

[0088] <Method for measuring viscosity> Measurements were taken using a cone-plate type rotational viscometer, VISCOMETER TVE-22L (manufactured by Toki Sangyo Co., Ltd.). The temperature inside the measurement container was fixed at 25°C using a high-temperature circulation bath, and a cone rotor (1°34' × R24) was used.

[0089] <Safety Evaluation Methods> Regarding safety, we confirmed the presence or absence of carcinogenicity labels in the Safety Data Sheets (SDS) of all raw materials used. We evaluated the product as "○" (not carcinogenic) if there was no carcinogenicity label and "×" (carcinogenic) if there was a carcinogenicity label.

[0090] <Method for measuring total light transmittance> <<Preparation of test specimens for transmittance measurement>> As shown in Figure 2, an OHP sheet 41a was placed on a glass substrate 40a, and a silicone mold 42 (shape: 20 mm long, 20 mm wide, average thickness 1 mm) was pressed into contact with the OHP sheet 41a. Next, the curing composition 43 was filled into the silicone mold 42, an OHP sheet 41b was placed over it, and the glass substrate 40b was placed on top of it. Next, using an ultraviolet irradiation device (UniJet E110Z HD_385nm, wavelength 385nm, manufactured by Ushio Inc.), an irradiation intensity of 200 mW / cm was applied through the glass substrate 40b. 2 The surface was irradiated with ultraviolet light for 5 minutes. Next, from the opposite side from the side that had been irradiated with ultraviolet light, the surface was irradiated with an intensity of 500 mW / cm² through the glass substrate 40a. 2 The specimen was irradiated with ultraviolet light for 5 minutes. Next, the OHP sheet 41b was peeled off, and the test specimen in which the curable composition 43 had hardened was removed from the silicone mold 42. The specimen was then left to stand for 24 hours in an environment of 23°C and 50% relative humidity to obtain a test specimen with an average thickness of 1 mm.

[0091] <<Method for measuring total light transmittance>> Using a DIRECT READING HAZEMETER (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the total light transmittance (Tt) in the thickness direction of the test specimens prepared above in accordance with JIS K7361-1 / HAZE: JIS K7136 was measured and evaluated according to the following evaluation criteria. A rating of B or higher indicates high whiteness and a level suitable for practical use. [Evaluation Criteria] A: Total light transmittance (Tt) is 30% or less B: Total light transmittance (Tt) is greater than 30% but less than or equal to 40% C: Total light transmittance (Tt) is over 40%

[0092] <Method for measuring bending strength> Aside from the dimensions being 40 mm in length, 10 mm in width, and an average thickness of 1 mm, the test specimens for measuring bending strength were manufactured in the same way as those for measuring light transmittance. The bending strength of each resulting rectangular hardened material was measured as follows. A universal testing machine (Autograph, model AG-I, manufactured by Shimadzu Corporation) was used to measure the bending strength of each three-dimensional object, using a 1kN load cell and a three-point bending jig. The distance between the supports was set to 24 mm, and the stress when the load point was displaced at a speed of 1 mm / min was plotted against the amount of strain, with the stress at the fracture point being defined as the maximum stress. A score of B or higher indicates a level that is actually usable. [Evaluation Criteria] A: Bending strength of 120 MPa or more B: Bending strength of 100 MPa or more and less than 120 MPa C: Bending strength is 100 MPa or less

[0093] <Method for measuring the refractive index (n1) of the cured monomer-containing liquid, the refractive index (n2) of the hard solid component, and the absolute value of the refractive index difference (|n1-n2|)> The refractive index was measured using an Abbe refractometer NAR-1T (manufactured by Atago Co., Ltd.) with a light source lamp D line (589.3 nm). The refractive index of the hard solid component was measured using the hard solid component (product) as is, and by Method B using an Abbe refractometer as described in JIS K 7142. For evaluating the refractive index of the cured monomer-based liquid, first, a test specimen made from the cured monomer-based liquid was prepared in the same manner as the test specimen for transmittance measurement, except that the monomer-based liquid was used instead of the curable composition. Next, the test specimen was scraped with water-resistant abrasive paper #400, and the refractive index of the resulting powder was measured using Method B with an Abbe refractometer as described in JIS K 7142.

[0094] [Table 2]

[0095] [Table 3]

[0096] [Table 4]

[0097] The details of the hard solid components used in the examples and comparative examples are as follows. (Hard solid component) • Admanano YA100CSM-C6: Surface-modified silica particles, volume-average particle size 100nm, Admatec Co., Ltd. • AdmaFine K180SM-C5: Surface-modified silica particles, volume-average particle size 180 nm, manufactured by Admatex Corporation. • AdmaFine 3SM-C11: Surface-modified silica particles, volume-average particle size 300 nm, manufactured by Admatex Corporation. • AdmaFine SC2500-SMJ: Surface-modified silica particles, volume-average particle size 500 nm, manufactured by Admatex Corporation. • Admanano YA100SP-C1: Surface-modified silica particles (phenylsilane modified), silica particles, volume-average particle size 100 nm, Admatec Co., Ltd. • Titanium dioxide: JR-806, titanium dioxide with an average particle size of 270 nm (silica content: 3% by mass, alumina content: 1% by mass), manufactured by Teika Co., Ltd.

[0098] AdmaFine is manufactured using the VMC method (a method of obtaining fine particles by cooling vaporized silicon), resulting in a broad particle size distribution. On the other hand, Admanano is manufactured using a wet synthesis method, resulting in a sharp particle size distribution. All surface-modified silica particles are silica whose surface has been modified with a silane coupling agent. Except for Admanano YA100SP-C1, all surface-modified silica particles are silica whose surface has been modified with a silane coupling agent that has an unsaturated double bond.

[0099] The curable compositions of Examples 1 to 12 all had a viscosity of 1,000 cp or less and could be stably ejected by an inkjet head. Comparison with comparative examples revealed that the curable compositions and three-dimensional molded objects of Examples 1 to 12 do not contain titanium dioxide, thus offering high safety. Furthermore, the three-dimensional molded objects obtained by curing the curable compositions exhibit excellent total light transmittance, resulting in high whiteness and improved strength. On the other hand, in Comparative Example 1, which used titanium dioxide, a white pigment with high shielding properties, it was found that although the cured product had high whiteness, it was unsafe and the cured strength was insufficient. In Comparative Example 2, which contained less than 3 volume percent of hard solid components, the total light transmittance of the cured product was too high, whiteness could not be obtained, and the cured strength was insufficient. In Comparative Examples 3 and 4, which contained more than 40 volume percent of hard solid components, the cured composition of Comparative Example 3, which had an increased amount of hard solid components with an average particle size of 100 nm, had high viscosity and was unsuitable for inkjet ejection, and the cured composition of Comparative Example 4, which had an increased amount of hard solid components with an average particle size of 500 nm, did not have sufficient cured strength.

[0100] Examples of the present invention are as follows: <1> Radical polymerizable monomers, It contains hard solid components with a volume-average particle diameter of 10 nm or more and 1,000 nm or less, The content of the hard solid component is 3% by volume or more and 40% by volume or less. The curable composition is characterized in that the absolute value of the difference (|n1-n2|) between the refractive index (n1) of the cured product of the components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more. <2> The difference in refractive index is 0.05 or more, <1> This is the curable composition described above. <3> The difference in refractive index is 0.07 or more, <2> This is the curable composition described above. <4> The hard solid component is silica whose surface has been modified with a silane coupling agent. <1> from <3> A curable composition as described in any of the following. <5> The silane coupling agent has an unsaturated double bond, <4> This is the curable composition described above. <6> The viscosity at 25°C is 1,000 mPa·s or less, <1> from <5> It is a curable composition as described in any of the above. <7> The content of the hard solid component is 5% by volume or more and 30% by volume or less relative to the total amount of the composition, <1> from <6> It is a curable composition as described in any of the above. <8> The volume-average particle size of the hard solid component is 100 nm or more and 500 nm or less. <1> from <7> It is a curable composition as described in any of the above. <9> The volume-average particle size of the hard solid component is 180 nm or more and 500 nm or less. <8> This is the curable composition described above. <10> The radical polymerizable monomer contains a (meth)acrylic monomer, <1> from <9> It is a curable composition as described in any of the above. <11> Furthermore, it contains a polymerization initiator, The content of the polymerization initiator is 0.1% by mass or more and 10.0% by mass or less based on the total amount of the composition. <1> from <10> It is a curable composition as described in any of the above. <12> Furthermore, the above contains a radical polymerizable oligomer. <1> from <11> It is a curable composition as described in any of the above. <13> The radical polymerizable oligomer has a urethane group, <12> This is the curable composition described above. <14> The content of the radical polymerizable oligomer is 1.0% by mass or more and 40.0% by mass or less of the total amount of the composition. <12> from <13> It is a curable composition as described in any of the above. <15> The aforementioned <1> from <14> A dispensing step in which a curable composition described in any of the above is dispensed by an inkjet method, The process includes a curing step of curing the discharged curable composition by irradiating it with an active energy ray, A method for manufacturing a three-dimensional object, characterized by sequentially repeating the aforementioned extrusion step and the aforementioned curing step. <16> The aforementioned <1> from <14> Dispensing means for dispensing a curable composition described in any of the above by an inkjet method, The apparatus for manufacturing three-dimensional molded objects is characterized by having a curing means for curing the discharged curable composition by irradiating it with active energy rays. <17> It contains hard solid components with a volume-average particle diameter of 10 nm to 1,000 nm. The content of the hard solid component is 3% by volume or more and 40% by volume or less. An artificial tooth prosthesis in which the absolute value of the difference (|n1-n2|) between the refractive index (n1) of the hardened material of components other than the hard solid component and the refractive index (n2) of the hard solid component is 0.04 or more, The hard solid component is spherical particles, and 50% of the primary particles of the spherical particles are distributed spaced apart from each other. This artificial tooth model is characterized by having a total light transmittance of 30% or less when using the artificial tooth model with an average thickness of 1 mm.

[0101] The aforementioned <1> from <14> A curable composition described in any of the above can solve the aforementioned problems of the conventional method and achieve the objectives of the present invention. The aforementioned <15> The method for manufacturing a three-dimensional object as described above, <16> The manufacturing apparatus for three-dimensional objects described herein aims to solve the aforementioned problems in the conventional method and achieve the following objectives. Specifically, the manufacturing method for three-dimensional objects and the manufacturing apparatus for three-dimensional objects aim to provide a manufacturing method and apparatus for three-dimensional objects that can produce three-dimensional objects using an inkjet method, which do not contain titanium dioxide, are highly safe, and have high strength and whiteness after curing. The aforementioned <17> The artificial tooth prosthesis described herein aims to solve the aforementioned problems of the conventional method and achieve the following objectives. Specifically, the objective is to provide an artificial tooth prosthesis that does not contain titanium dioxide, is highly safe, and has high strength and whiteness after hardening. [Prior art documents] [Patent Documents]

[0102] [Patent Document 1] Patent No. 6774659 [Explanation of Symbols]

[0103] 1. Model part forming material 2. Support part forming material 10 Model Section 20 Support Department 30. Manufacturing equipment for three-dimensional objects 31 Head unit (an example of a dispensing means) 32 Head unit (an example of a dispensing means) 33. Ultraviolet irradiation machine (an example of a curing method) 34 rollers 35 Carriage 36 circuit boards 37 stages

Claims

1. Radical polymerizable monomers, It contains hard solid components with a volume-average particle diameter of 10 nm or more and 1,000 nm or less, The content of the hard solid component is 3% by volume or more and 40% by volume or less. The refractive index (n) of the cured product of components other than the hard solid component. １ ) and the refractive index (n) of the hard solid component. ２ The absolute value of the difference between (|n) １ -n ２ A curable composition characterized in that the |) is 0.04 or higher.

2. The curable composition according to claim 1, wherein the difference in refractive index is 0.05 or more.

3. The curable composition according to claim 2, wherein the difference in refractive index is 0.07 or more.

4. The curable composition according to any one of claims 1 to 3, wherein the hard solid component is silica surface-modified with a silane coupling agent.

5. The curable composition according to claim 4, wherein the silane coupling agent has an unsaturated double bond.

6. A curable composition according to any one of claims 1 to 5, wherein the viscosity at 25°C is 1,000 mPa·s or less.

7. The curable composition according to any one of claims 1 to 6, wherein the content of the hard solid component is 5% by volume or more and 30% by volume or less with respect to the total amount of the composition.

8. The curable composition according to any one of claims 1 to 7, wherein the volume-average particle size of the hard solid component is 100 nm or more and 500 nm or less.

9. The curable composition according to claim 8, wherein the volume-average particle size of the hard solid component is 180 nm or more and 500 nm or less.

10. The curable composition according to any one of claims 1 to 9, wherein the radical polymerizable monomer contains a (meth)acrylic monomer.

11. Furthermore, it contains a polymerization initiator, The curable composition according to any one of claims 1 to 10, wherein the content of the polymerization initiator is 0.1% by mass or more and 10.0% by mass or less based on the total amount of the composition.

12. Furthermore, the curable composition according to any one of claims 1 to 11, further containing a radically polymerizable oligomer.

13. The curable composition according to claim 12, wherein the radical polymerizable oligomer has a urethane group.

14. The curable composition according to any one of claims 12 to 13, wherein the content of the radical polymerizable oligomer is 1.0% by mass or more and 40.0% by mass or less based on the total amount of the composition.

15. A dispensing step of dispensing a curable composition according to any one of claims 1 to 14 by an inkjet method, The process includes a curing step of curing the discharged curable composition by irradiating it with an active energy ray, A method for manufacturing a three-dimensional object, characterized by sequentially repeating the discharge step and the curing step.

16. Dispensing means for dispensing a curable composition according to any one of claims 1 to 14 by an inkjet method, A manufacturing apparatus for three-dimensional molded objects, characterized by comprising a curing means for curing the discharged curable composition by irradiating it with active energy rays.

17. It contains hard solid components with a volume-average particle diameter of 10 nm to 1,000 nm. The content of the hard solid component is 3% by volume or more and 40% by volume or less. The refractive index (n) of the cured product of components other than the hard solid component. １ ) and the refractive index (n) of the hard solid component. ２ The absolute value of the difference between (|n) １ -n ２ An artificial tooth prosthesis in which |) is 0.04 or higher, The hard solid component is spherical particles, and 50% of the primary particles of the spherical particles are distributed spaced apart from each other. An artificial tooth model characterized in that, when using the artificial tooth model with an average thickness of 1 mm, the total light transmittance is 30% or less.

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