Manufacturing method for three-dimensional objects

Abstract

To provide a method for manufacturing a three-dimensional shaped object that can efficiently form a highly aesthetic three-dimensional shaped object having parts colored with different colors.SOLUTION: The present invention relates to a method for producing a three-dimensional shaped object having parts colored with different colors, and the method for producing the three-dimensional shaped object includes: a dividing process for dividing the three-dimensional data of the three-dimensional shaped object into at least two parts; and a shaping process for shaping the at least two parts after the division so that the first part and the second part, which are in contact with each other, are colored in different colors.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a three-dimensional object.

Background Art

[0002] As a method of forming a three-dimensional object having portions colored with different colors by a 3D printer, for example, there are (1) a method of forming a single-color object and then coloring the surface layer, and (2) a method of forming while arranging a plurality of color forming materials in each layer. In the method (1) above, since the inside of the object cannot be colored, a three-dimensional object with a transparent feeling cannot be formed. In the method (2) above, since it is necessary to supply a plurality of color forming materials during forming, data processing and processes become complicated, and when transparency is desired, the color arrangement has to be specified every time according to the target shape, and there is the complexity of defining the process therefor.

[0003] One application example of a three-dimensional object having portions colored with different colors is an artificial tooth. The method of manufacturing an artificial tooth by a conventional dental laboratory process (building up) is to manually arrange a highly transparent material on the surface layer and perform coloring as necessary. Since the coloring is adjusted manually, there is a problem that it is very laborious. Therefore, for example, a method of forming a three-dimensional object having a color gradation in the Z direction by gradually replacing the three-dimensional forming material while forming has been proposed (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1 above, a gradation that makes the surface side transparent and the inside dark like an actual tooth cannot be reproduced. Also, there are limitations in the forming direction and cutting direction, and arrangement adjustment is required during simultaneous production of a plurality of them, and there is a problem that it is not suitable for mass production.

[0005] The present invention aims to provide a method for manufacturing three-dimensional objects that can efficiently create aesthetically pleasing three-dimensional objects having parts colored in different colors. [Means for solving the problem]

[0006] The present invention is a means for solving the aforementioned problems. tooth shape A method for manufacturing a three-dimensional object having parts colored in different colors includes a division step of dividing the three-dimensional data of the three-dimensional object into at least two parts, and a molding step of shaping the object such that a first part and a second part, which are in contact with each other, are colored in different colors. The first portion is the outermost surface portion of the three-dimensional object, the transmittance of the first portion is higher than that of the second portion, and the first portion has at least one portion that becomes thicker from the cervical portion toward the incisal edge. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for manufacturing three-dimensional objects that can efficiently create aesthetically pleasing three-dimensional objects having parts colored in different colors. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of a method for dividing the three-dimensional data of a three-dimensional object into at least two parts in the division step of the manufacturing method of a three-dimensional object according to the present invention. [Figure 2A] Figure 2A shows an example of 3D data when viewing a three-dimensional object from the front. [Figure 2B] Figure 2B shows an example of 3D data when viewing a three-dimensional object from the side. [Figure 3] Figure 3 is a schematic diagram showing an example of a manufacturing apparatus for three-dimensional objects used in the manufacturing method of three-dimensional objects according to the present invention. [Figure 4] Figure 4 is a photograph showing the artificial tooth fabricated in Example 1. [Figure 5] Figure 5 is a photograph showing the artificial tooth fabricated in Example 2. [Figure 6] Figure 6 is a photograph showing the artificial tooth fabricated in Comparative Example 1. [Figure 7] Figure 7 is a photograph showing the artificial tooth fabricated in Comparative Example 2. [Figure 8] Figure 8 is a photograph showing the artificial tooth fabricated in Comparative Example 3. [Modes for carrying out the invention]

[0009] (Method of manufacturing three-dimensional objects) The present invention provides a method for manufacturing a three-dimensional object, which includes a division step and a molding step, and further includes other steps as necessary.

[0010] Conventional SLA (stereolithography) technology requires changing the curing composition during the manufacturing process, and even then, the gradation direction is limited to the Z-direction during manufacturing. In this invention, when reproducing a color gradient in a three-dimensional object, the data is divided into at least two parts, a color is assigned to each divided part, and the object is fabricated using the material jetting (MJ) method. This allows for a more precise expression of color characteristics such as transparency, and enables the efficient fabrication of aesthetically pleasing three-dimensional objects.

[0011] <Dividing process> The division process is a method for manufacturing a three-dimensional object having parts colored in different colors, and involves dividing the three-dimensional data of the three-dimensional object into at least two parts.

[0012] The aforementioned 3D data refers to data obtained through 3D scanning or the like, which can be input into a 3D printer. The 3D data may consist of one data item or multiple data items. There are no particular restrictions on the method of acquiring the 3D data, and it can be appropriately selected according to the purpose. Examples include scanning the actual object to be printed using a 3D scanner, modeling the data using 3DCAD software, or creating the data using 3DCG tools. Note that 3D scanning can also be done using the scanner attached to the 3D printer.

[0013] The acquired 3D data is divided into at least two parts. There are no particular restrictions on the number of divisions of the 3D data, as long as it is two or more, and can be appropriately selected depending on the purpose, but it is preferable that it be between two and five parts. One example of dividing 3D data is to divide it into two parts, with the surface of the 3D object being the first part and the inside of the 3D object being the second part. For example, one could take 3D data A obtained by 3D scanning the actual object to be modeled, and create 90% 3D data B by setting its width and height to 90%. By aligning the centroids of 100% 3D data A and 90% 3D data B, one could create 3D data C(AB) by removing the overlapping portion of 90% 3D data B from 3D data A using Boolean operations.

[0014] By performing a surface model conversion on the divided 3D data, data in STL (Standard Triangulated Language) format is created. When data in STL format is input to a 3D printer, the 3D printer converts the input STL data into a 2D image dataset for printing. The aforementioned 2D image dataset for printing is a dataset containing multiple 2D image data for printing, and the 2D image data for printing is two-dimensional slice data obtained by slicing STL format data according to the resolution of the 3D printer in the Z-axis direction. Based on this 2D image data for printing, a three-dimensional object can be fabricated by repeatedly extruding multiple types of curable compositions into predetermined areas with a predetermined extrusion amount using a 3D printer and curing them.

[0015] <Modeling process> The molding process involves shaping the object such that, among the two parts after division, the first and second parts that are in contact with each other are colored in different colors. The first part is the outermost surface of the three-dimensional object. That is, in the three-dimensional object, the first part is on the outside and the second part is on the inside. This makes it possible to reproduce a gradient similar to that of actual teeth, where the surface is transparent and the inside is a darker color.

[0016] A method for creating a model in which the first and second parts are colored in different colors involves extruding curable compositions colored in different colors using an inkjet method based on divided 3D data, and then curing them. For example, this can be done by using a clear curable composition for the first part and a color curable composition for the second part. The method of discharge is not particularly limited, but examples include continuous injection type and on-demand type. Examples of on-demand type discharge methods include piezoelectric type, thermal type and electrostatic type. The aforementioned ejection process preferably involves ejecting the curable composition onto a stage having a lifting function using an inkjet method. The curable composition ejected onto the stage forms a liquid film.

[0017] The curing treatment is performed by irradiating the curable composition with active energy rays. In the curing process described above, the liquid film made of the curable composition formed on the stage is cured by irradiation with active energy rays.

[0018] 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 the 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.

[0019] In the method for manufacturing a three-dimensional object of the present invention, by sequentially repeating the extrusion process and the hardening process in the molding process, a three-dimensional object of a desired shape having parts colored in different colors can be manufactured.

[0020] <Other processes> The aforementioned other processes are not particularly limited and can be selected as appropriate depending on the purpose, for example, a smoothing process.

[0021] -Smoothing process- 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.

[0022] Here, Figure 1 is a schematic diagram showing an example of a method for dividing the three-dimensional data of a three-dimensional object into at least two parts (for example, a first part and a second part) in the division step of the manufacturing method of a three-dimensional object of the present invention. As shown in Figure 1, 3D data acquired by a 3D scanner or the like is divided into two parts, a first part and a second part. Each divided 3D data is converted into slice data, and this slice data is input into a 3D printer to create a 3D object with a different color for each divided part. Preferably, dithering processing is included in at least one of the XY and Z directions as needed. This allows the dithering processing used in normal 2D color printing to be applied to the Z direction as well, enabling gradation using multiple pixels. Furthermore, if adjusting the amount of curable composition dispensed per pixel (small, medium, or large droplets) results in insufficient gradation, the amount of curable composition dispensed per layer is adjusted using the same methods as in 2D color printing (e.g., error diffusion). In other words, the concept of error diffusion used in 2D color printing can be similarly applied to the Z-direction. The aforementioned error diffusion method is a binarization method used in fax machines and other applications. While simple binarization divides an image into two tones based on a 50% density, the error diffusion method propagates the quantization error during binarization into the surrounding area, allowing for the pseudo-reproduction of intermediate densities based on the density of black and white areas.

[0023] Here, Figure 2A is a 3D data diagram of the three-dimensional object as viewed from the front. Figure 2B is a 3D data diagram of the three-dimensional object as viewed from the side. First, as shown in Figures 2A and 2B, a 90% scale 3D data B is created by taking the 3D data A obtained from the actual object to be modeled by 3D scanning and reducing its width and height by 90%. Next, the centroids of 3D data A and 90% 3D data B in the horizontal plane (X, Y plane) are aligned, and 3D data C(AB) is created by removing the overlapping portion of 3D data A with 90% 3D data B using a Boolean operation. Next, by performing slice processing on the three-dimensional data C and the three-dimensional data B respectively and converting them into slice data in bitmap (bmp) format, slice data of the first part (C part) and the second part (B part) can be obtained. Next, using the clear curable composition of the curable composition set for the first part (C part) and the color curable composition of the curable composition set for the second part (B part), a three-dimensional object (artificial tooth) that reproduces a gradation with a transparent surface side and a dark color inside like an actual tooth can be formed by an inkjet 3D printer.

[0024] In the present invention, from the viewpoint of aesthetics, it is preferable that the transmittance of the first part is higher than the transmittance of the second part. The difference (T1 - T2) between the transmittance (T1) of the first part and the transmittance (T2) of the second part is preferably 10% or more, and more preferably 20% or more. For the transmittance, for example, for a test piece having the first part and the second part prepared under predetermined conditions, using a DIRECT READING HAZEMETER (manufactured by Toyo Seiki Co., Ltd.), the total light transmittance of the first part and the second part of the test piece can be measured. In addition, a test piece consisting only of the first part and a test piece consisting only of the second part can be separately prepared, and the total light transmittance of each test piece can also be measured.

[0025] In the present invention, the L * a * b * value of L in the color system * value + a * value + b * value is preferably smaller than the L * a * b * value of L in the color system * value + a * value + b * value of the second part from the viewpoint of aesthetics. It is preferable that ΔE represented by the following formula 1 is 10 or more, and more preferably 15 or more. [Formula 1] ΔE = {(L2 - L1)2 +(b2-b1) 2 +(a2-a1) 2} 0.5 However, in the above formula 1, L1 is the L of the first part. * The value, L2 is the L of the second part. * The value, b1 is the b of the first part. * The value, b2 is the second part of b * The value, a1 is the a of the first part. * The value a2 is the a of the second part. * Represents a value. Said L * value + a * value + b * The L values ​​and ΔE are obtained, for example, from a test specimen having a first part and a second part prepared under predetermined conditions, using a spectrophotometer (eXact, manufactured by Xrite, condition: D50 / 2) and measuring the L values ​​of the first part and the second part of the test specimen. * value, a * value, b * The value can be measured. Alternatively, test specimens consisting only of the first part and test specimens consisting only of the second part can be prepared separately, and the total light transmittance of each test specimen can be measured.

[0026] In the present invention, it is preferable that the three-dimensional molded object is tooth-shaped and has at least one portion near the surface that becomes thicker from the cervical portion towards the incisal edge.

[0027] The following describes the curing composition and curing composition set used in the method for manufacturing three-dimensional molded objects according to the present invention.

[0028] <Curing composition> 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. The curable composition contains a monomer, a polymerization initiator, a surface tension modifier, and a colorant, and further contains other components as needed.

[0029] <Curing type composition set> The curing composition set is a combination of a clear curing composition, a color curing composition including a white curing composition, a yellow curing composition, a magenta curing composition, a cyan curing composition, and a black curing composition, and a support curing composition. The clear-curing composition forms the desired shape of a three-dimensional object (hereinafter also referred to as the "model part") upon curing. The color-curing composition, upon curing, forms a colored area within the model part that exhibits a different color from the area formed by the clear-curing composition. Furthermore, the support-curing composition forms the shape of a support portion that supports the model portion as it hardens.

[0030] <<Color-curing composition>> The color-curable composition contains a radical polymerizable compound and a colorant, and preferably contains a polymerization initiator, a surfactant, a polymerization inhibitor, and a dispersant, and may further contain other components as needed.

[0031] -Radical polymerizable compounds- Radical polymerizable compounds are compounds that can form polymers by radical polymerization, and are typically monomer units 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. Radical polymerizable monofunctional monomers, radical polymerizable polyfunctional monomers, and radical polymerizable oligomers are all monomer units of cured products obtained by radical polymerization using active energy rays. That is, in the present invention, "radical polymerizable monomer" refers to a monomer molecule having one or more radical polymerizable functional groups, and "radical polymerizable oligomer" refers to an oligomer molecule having one or more radical polymerizable functional groups. "Oligomer" refers to a molecule having structural units derived from a small number of monomers, the number of which may vary depending on the structure of the monomer and the application of the oligomer, but is typically preferably between 2 and 20.

[0032] When a radical polymerizable compound is used as the polymerizable compound, 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. Furthermore, by using a radically polymerizable monomer as the radically polymerizable compound, the viscosity increase of the color-curable composition can be further suppressed. Furthermore, by using a radically polymerizable monofunctional monomer as the radically polymerizable compound, the viscosity increase of the color-curable composition can be further suppressed. Furthermore, 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.

[0033] Examples of radically polymerizable monofunctional monomers include acrylamide, N,N-dimethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, hydroxyethylacrylamide, 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. These may be used individually or in combination of two or more.

[0034] Examples of 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.

[0035] 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.

[0036] 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.

[0037] The radical polymerizable oligomer is preferably a monomer with one to six functionalities, and more preferably a monomer with two to three functionalities. These may be used individually or in combination of two or more. Furthermore, by using a radical polymerizable oligomer that has a urethane group, interactions occur between the side chains in the polymer, improving the toughness of the cured product. Moreover, it is more preferable that the radical polymerizable oligomer having a urethane group is a urethane acrylate oligomer.

[0038] Commercially available radical polymerizable oligomers can be used, such as UV-6630B (UV-curable urethane acrylate oligomer, molecular weight: 3,000, 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.

[0039] 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 color-curable compositions 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.

[0040] The content of the radical polymerizable compound is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, and most preferably 80% by mass or more, based on the total amount of the color-curable composition. Furthermore, 99% by mass or less is preferred, and 95% by mass or less is more preferred.

[0041] The content of radically polymerizable monofunctional monomers is preferably 30% by mass or more, more preferably 40% by mass or more, based on the total amount of the color-curable composition. Furthermore, it is preferably 99% by mass or less, and more preferably 95% by mass or less.

[0042] The content of the radically polymerizable polyfunctional monomer is preferably 10% by mass or more, based on the total amount of the color-curable composition. It is also preferably 40% by mass or less, and more preferably 30% by mass or less.

[0043] The content of the radical polymerizable oligomer is preferably 1% by mass or more, more preferably 10% by mass or more, relative to the total amount of the color-curable composition. Furthermore, it is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0044] -Colorants- The colorant is included in the color-curing composition to form the colored area described above. The colorant is preferably a dye or pigment that can be dissolved or stably dispersed in a color-curable composition, and more preferably a pigment from the viewpoint of durability and safety. In this disclosure, the pigment is functionally distinct from the hard solid component described later, and the hard solid component is not included in the pigment.

[0045] Inorganic or organic pigments can be used as pigments. These may be used individually or in combination of two or more. Mixed crystals may also be used as pigments. As inorganic pigments, titanium dioxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chromium yellow can be used, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method. Organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, and aniline black. The volume-average particle size of the pigment is preferably between 10 nm and 1000 nm, from the viewpoint of the dispersion stability of the pigment and the image density in the colored region. The volume-average particle size can be measured, for example, using a particle size analyzer (NanoTrac Wave-UT151, manufactured by MicroTrac-Bell Co., Ltd.).

[0046] Acid dyes, direct dyes, reactive dyes, and basic dyes can be used as dyes. These may be used individually or in combination of two or more types.

[0047] The colorant content is preferably 0.1% by mass or more, and more preferably 0.1% by mass or more and 10% by mass or less, relative to the total amount of the color-curable composition. By having 0.1% by mass or more, even in the manufacturing method of the three-dimensional object of the present invention, which involves a smaller discharge amount of the color-curable composition compared to general molding methods, the image density in the colored area can be sufficiently improved.

[0048] -Polymerization initiator- Any substance that generates radicals or cations upon irradiation with active energy rays such as light can be used as a polymerization initiator. Examples of active energy rays include visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, and gamma rays. A single polymerization initiator may be used, or two or more may be used in combination. Furthermore, the polymerization initiator content is preferably 0.1% to 10% by mass, and more preferably 1% to 5% by mass, relative to the total amount of the color-curable composition. Examples of radical photopolymerization 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. Examples of cationic photopolymerization initiators include commercially available products such as UVI-6950, UVI-6970, UVI-6974, UVI-6990 (all manufactured by Union Carbide), Adeka Optomer SP-150, SP-151, SP-170, SP-172 (all manufactured by Asahi Denka Kogyo Co., Ltd.), and Irgacure. Examples include 261 (manufactured by Ciba Specialty Chemicals), CI-2481, CI-2624, CI-2639, CI-2064 (manufactured by Nippon Soda Co., Ltd.), CD-1010, CD-1011, CD-1012 (manufactured by Sartomer Co., Ltd.), DTS-102, DTS-103, NAT-103, NDS-103, TPS-103, MDS-103, MPI-103, BBI-103 (manufactured by Midori Chemical Co., Ltd.), PCI-061T, PCI-062T, PCI-020T, PCI-022T (manufactured by Nippon Kayaku Co., Ltd.). These may be used individually or in combination of two or more types.

[0049] - Surfactants - Preferably, the surfactant is a compound with a molecular weight of 200 to 5,000. Specifically, examples include PEG-type nonionic surfactants [1-40 molar adducts of nonylphenol ethylene oxide (hereinafter abbreviated as EO), 1-40 molar adducts of stearate EO, 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.

[0050] -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.

[0051] -Dispersant- A dispersant is an additive that has the function of stably dispersing solid components, such as pigments, in a color-curable composition by adsorbing them onto the surface of the solid components. Any known dispersant can be used as appropriate.

[0052] -Other ingredients- Other components are not particularly limited and can be selected as appropriate depending on the purpose, and examples include organic solvents, water, and hard solid components.

[0053] --Organic solvent-- Color-curable compositions may contain organic solvents, but it is preferable if they do not. Compositions that do not contain organic solvents, especially volatile organic compounds (VOC-free), offer greater safety at the location where the composition is handled and help prevent environmental pollution. Note that "organic solvents" refer to common non-reactive organic solvents such as ethers, ketones, xylene, ethyl acetate, cyclohexanone, and toluene, and should be distinguished from polymerizable compounds. Furthermore, "not containing" organic solvents means substantially not containing them (for example, not containing enough organic solvents to affect the properties of the color-curable composition), and it is preferable that the content is less than 0.1% by mass of the total amount of the color-curable composition.

[0054] --water-- The color-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 color-curing composition), and it is preferable that the water content is less than 1% by mass of the total amount of the color-curing composition. 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 part formed by the support ink described later.

[0055] --Hard solid component-- The color-curable composition may contain hard solid components as described later, but it is preferable to omit them if possible. As mentioned above, the color-curable composition preferably contains pigments as solid colorants, but if hard solid components are included as additional solid components, it becomes necessary to investigate the conditions for stably dispersing both the pigments and hard solid components in the color-curable composition, which increases the difficulty in formulation and manufacturing of the color-curable composition. Furthermore, "not containing" hard solid components means substantially not containing them (for example, not containing them to the extent that the properties of the hard solid components affect the color-curable composition), and it is preferable that the content is less than 0.1% by mass of the total amount of the color-curable composition. Furthermore, if the color-curing composition does not contain hard solid components, a decrease in strength is expected in the colored areas of the three-dimensional object formed by the color-curing composition. However, as described above, by performing the molding method so that there are overlapping areas between the clear and colored areas within the layer, clear areas derived from the clear-curing composition containing hard solid components are arranged throughout the entire three-dimensional object. This makes it possible to achieve both improved dispersion stability in the color-curing composition and suppression of strength reduction in the colored areas.

[0056] Color-curable compositions suitable for use with inkjet printing systems are preferably low in viscosity, considering factors such as nozzle ejection performance. Therefore, in one embodiment, the viscosity of the color-curable composition is preferably 1,000 mPa·s or less, more preferably 200 mPa·s or less, and even more preferably 150 mPa·s or less at a 25°C environment. Furthermore, from the viewpoint of ejection performance and molding accuracy, it is preferable that the viscosity is 9 mPa·s or more at a 25°C environment. During molding, the viscosity of the color-curable composition can be adjusted by adjusting the temperature of the inkjet head and ink flow path. 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.

[0057] Furthermore, considering ejection stability and molding accuracy, it is preferable that the color-curable composition usable for inkjet applications has a surface tension in the range of 20 mN / m to 40 mN / m at a 25°C environment. Therefore, in one embodiment, the color-curable composition has a surface tension of 20 mN / m to 40 mN / m at a 25°C environment. Surface tension can be measured by conventional methods, such as the plate method, ring method, and pendant drop method.

[0058] The container for the color-curing composition refers to the container in which the color-curing composition is contained. The container containing the color-curing composition can be used as a cartridge or bottle, which eliminates the need to directly touch the color-curing composition during transport and replacement, thus preventing contamination of hands and clothing. It also prevents the contamination of the color-curing 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.

[0059] <<Clear curing type composition>> The clear curing composition contains a radical polymerizable compound and a hard solid component, and preferably contains a polymerization initiator, a surfactant, a polymerization inhibitor, and a dispersant, and may further contain other components as needed. In the following, various components included in the clear curing composition will be described, but the radical polymerizable compounds, polymerization initiators, surfactants, polymerization inhibitors, and dispersants can be used in the same way as in the color curing composition described above, so their descriptions will be omitted. Furthermore, it is preferable that the physical properties of the clear curing composition are the same as those of the color curing composition, and that the container for the clear curing composition is the same as that for the color curing composition, so these descriptions will also be omitted.

[0060] -Hard solid component- The hard solid component is included to improve the elastic modulus, strength, and impact resistance of the cured product of the clear curing composition. In this disclosure, "hard" refers to a property in which the shape is not easily changed by external stress. Whether or not something is hard can be determined by a person skilled in the art based on criteria known in the art, such as Vickers hardness and modulus of elasticity. In a preferred embodiment, the modulus of elasticity of a hard solid material is 4 GPa or higher, and more preferably 5 GPa or higher. The modulus of elasticity can be determined, for example, according to JIS K 7161, JIS K 7171, ISO 14577, etc. In this disclosure, "solid component" refers to a component that can maintain a solid state in a liquid such as a composition. Furthermore, the solid component is preferably in the form of particles in the liquid. Moreover, the solid component is preferably dispersed in the liquid. In this disclosure, the hard solid component is functionally distinct from the colorants described above. For example, pigments, which are colorants in the solid component, are not included in the hard solid component.

[0061] There are no particular restrictions on the hard solid components, and they can be appropriately selected depending on the purpose. Examples include glass, silica, alumina, zirconia, wollastonite, potassium titanate, xonotlite, gypsum fiber, aluminum borate, aramid fiber, carbon fiber, glass fiber, talc, mica, glass flakes, polyoxybenzoyl whiskers, and various resins.

[0062] Furthermore, for hard solid components such as glass, silica, and alumina that have hydroxyl groups on their surface, it is preferable to use those that have been surface-modified using a silane coupling agent.

[0063] There are no particular restrictions on the silane coupling agent; for example, vinyl methoxysilane, vinyl ethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, styryl p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldi Examples include methoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-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.

[0064] The content of the hard solid component is preferably 0.5% to 40% by volume relative to the total volume of the clear curable composition, and more preferably 1% to 20% by volume. A hard solid component content of 0.5% or more relative to the total volume of the clear curable composition allows the properties of the hard solid component to be reflected in the three-dimensional object. Furthermore, a hard solid component content of 40% or less relative to the total volume of the clear curable composition helps to suppress the brittleness of the three-dimensional object.

[0065] There are no particular restrictions on the shape of the hard solid component; it may be spherical, rod-shaped, or amorphous, and may also be hollow particles, porous particles, core-shell structure particles, etc.

[0066] The volume-average particle size of the hard solid component is preferably 10 nm to 1,000 nm, and more preferably 120 nm to 300 nm. If the volume-average particle size of the hard solid component is 10 nm or larger, the properties of the hard solid component can be fully reflected in the three-dimensional object. Furthermore, if it is 1,000 nm or smaller, the ejection stability using the inkjet method can be improved. Moreover, considering the dispersion stability of the hard solid component in the clear curing composition, it is more preferable that it be 300 nm or smaller.

[0067] -Other ingredients- Other components are not particularly limited and can be appropriately selected depending on the purpose, and examples include organic solvents, water, and colorants. Note that the organic solvents and water are the same as those in the color-curable composition described above, so their explanations will be omitted.

[0068] <<Support-curing type composition>> The support-curing composition has the property of being able to disintegrate when water or the like is applied to the cured product of the support-curing composition, and the support can be easily removed from the model after molding. There are no particular restrictions on the support-curing composition, and any known composition can be used as appropriate. For example, the support-curing composition disclosed in Japanese Patent Publication No. 2018-70731 can be used.

[0069] The following describes a method for creating three-dimensional objects and a manufacturing apparatus for three-dimensional objects when a curable composition is used as a model part forming material and a support part forming material.

[0070] Here, Figure 3 is a schematic diagram showing an example of a three-dimensional object manufacturing apparatus. The three-dimensional object manufacturing apparatus 30 in Figure 3 has head units 31 and 32, an ultraviolet irradiation unit 33, a roller 34, a carriage 35, and a stage 37. Head unit 31 discharges the model part forming material 1. Head unit 32 discharges the support part forming material 2. The roller 34 smooths the liquid film of the model part forming material 1 and the support part forming material 2. The ultraviolet irradiation unit 33 irradiates the discharged model part forming material 1 and the support part forming material 2 with ultraviolet light to cure them. The carriage 35 moves each of the means such as the head units 31 and 32 back and forth in the X direction in Figure 3. The stage 37 moves the substrate 36 in the Z direction shown in Figure 3 and in the Y direction, which is the depth direction in Figure 3. Note that movement in the Y direction may be performed by the carriage 35 instead of the stage 37.

[0071] 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.

[0072] Examples of metals that can be used for the roller 34 include SUS300 series, SUS400 series, SUS600 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.

[0073] Furthermore, to prevent the curing composition 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.

[0074] The following describes the molding process of a molded object (cured object) in which the extrusion process and the curing process are sequentially repeated in the manufacturing method of the three-dimensional molded object of the present invention. The engine of the three-dimensional object manufacturing apparatus 30 shown in Figure 3 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 part 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 part, forming a liquid film where adjacent droplets are in contact. When one object is to be manufactured, a liquid film with the cross-sectional shape is formed in the middle 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The object created 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 it is created. 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 immersed in a solvent to disintegrate and remove it. 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 is selected to be water-disintegrable.

[0080] The three-dimensional objects produced by the manufacturing method of the present invention can reproduce the gradient of a real tooth, with a transparent surface and a darker color on the inside, and have a color close to that of a real tooth, making them aesthetically pleasing and suitable for use in dental materials such as artificial teeth. In addition to dental materials such as artificial teeth, they can also be used in eyeglass frames, shoe outsoles, midsoles, grips such as handles, hearing aids, earphones, denture bases, prosthetics, and more. 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. [Examples]

[0081] The following describes embodiments of the present invention, but the present invention is not limited in any way to these embodiments.

[0082] (Preparation example 1 of clear curing type composition A) -Preparation of Clear Curing Composition A1- Clear curable composition A1 was prepared by mixing 38 parts by mass of tricyclodecane dimethylol diacrylate ("KAYARADR-684", manufactured by Nippon Kayaku Co., Ltd.), 7 parts by mass of acryloylmorpholine ("ACMO", manufactured by KJ Chemicals Co., Ltd.), 34.7 parts by mass of dicyclopentanyloxyethyl acrylate ("FA-512", manufactured by Hitachi Chemical Co., Ltd.), 10 parts by mass of tetrahydrofurfuryl acrylate ("SR285", manufactured by Sartomer Co., Ltd.), 10 parts by mass of trimethylolpropane triacrylate ("SR3515", manufactured by Sartomer Co., Ltd.), 0.2 parts by mass of polyether-modified silicone surfactant ("KF-945", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.1 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide ("Irgacure 819", manufactured by BASF Japan Ltd.).

[0083] (Preparation example 1 of color-curable composition B) -Preparation of Magenta-Curable Composition B1- Magenta-curable composition B1 was prepared by mixing 5 parts by mass of N-vinylcaprolactam ("VCAP", manufactured by ISP), 30 parts by mass of isobornyl acrylate ("IBXA", manufactured by Osaka Organic Chemical Industry Co., Ltd.), 34.9 parts by mass of tetrahydrofurfuryl acrylate ("SR285", manufactured by Sartomer), 30 parts by mass of magenta pigment (pigment: PR122, dispersant: BYK9151), and 0.1 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide ("Irgacure 819", manufactured by BASF Japan Ltd.).

[0084] (Preparation example 2 of color-curable composition B) -Preparation of White Curing Composition B2- White curable composition B2 was prepared by mixing 5 parts by mass of tricyclodecane dimethylol diacrylate ("KAYARADR-684", manufactured by Nippon Kayaku Co., Ltd.), 20 parts by mass of isodecyl acrylate ("SR395N5", manufactured by Sartomer Co., Ltd.), 44.9 parts by mass of tetrahydrofurfuryl acrylate ("SR285", manufactured by Sartomer Co., Ltd.), 30 parts by mass of white pigment (pigment: TiO2, dispersant: Solspers 32000), and 0.1 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide ("Irgacure 819", manufactured by BASF Japan Ltd.).

[0085] (Preparation example 3 of color-curable composition B) -Preparation of cyanide-curable composition B3- Cyanide-curable composition B3 was prepared by mixing 5 parts by mass of polyethylene glycol (600) diacrylate ("SR610NS", manufactured by Sartomer), 40 parts by mass of isobornyl acrylate ("IBXA", manufactured by Osaka Organic Chemical Industry Co., Ltd.), 44.9 parts by mass of tetrahydrofurfuryl acrylate ("SR285", manufactured by Sartomer), 30 parts by mass of cyanide pigment (pigment: PB15:4, dispersant: Solspers 32000), and 0.1 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide ("Irgacure 819", manufactured by BASF Japan Ltd.).

[0086] (Preparation example 4 of color-curable composition B) -Preparation of yellow curing type composition B4- Yellow curable composition B4 was prepared by mixing 10 parts by mass of isobornyl acrylate ("IBXA", manufactured by Osaka Organic Chemical Industry Co., Ltd.), 59.9 parts by mass of tetrahydrofurfuryl acrylate ("SR285", manufactured by Sartomer Co., Ltd.), 30 parts by mass of yellow pigment (pigment: PY150, dispersant: BYK9151), and 0.1 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide ("Irgacure 819", manufactured by BASF Japan Ltd.).

[0087] (Example 1 of preparation of a support-curing composition) 30 parts by mass of acryloylmorpholine (manufactured by KJ Chemicals Co., Ltd.), 20 parts by mass of 1,5-pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), polypropylene glycol 2 (trade name: Actcol D-1000, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd., number average molecular weight: 1,000), and 2 parts by mass of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF) were added and stirred to obtain a support-curing composition.

[0088] (Example of preparation of color-curing composition A for molding) The clear curing composition A1 and the white curing composition B2 were mixed so that the total light transmittance of the cured product was 70%. The hardened product L is obtained from the resulting mixture. * a * b * L in color systems * The value is 73.5, a * The value is 1.7, b * The magenta-curing composition B1, the cyan-curing composition B3, and the yellow-curing composition B4 were further mixed to obtain a value of 7.7, thereby preparing a color-curing composition A for molding.

[0089] (Example of preparation of color-curing composition B for molding) The clear curing composition A1 and the white curing composition B2 were mixed so that the total light transmittance of the cured product was 35%. The hardened product L is obtained from the resulting mixture. * a * b * L in color systems * The value is 72.3, a * The value is 8.2, b * The magenta-curing composition B1, the cyan-curing composition B3, and the yellow-curing composition B4 were further mixed to prepare a color-curing composition B for molding, so that the value was 29.0.

[0090] (Curing type composition set) The above-prepared color curing composition A, the above-prepared color curing composition B, and the support curing composition were combined to form a curing composition set.

[0091] (Examples 1-2 and Comparative Examples 1-3) In the three-dimensional object manufacturing apparatus shown in Figure 3, the inkjet head (product name: MH28) In tanks connected to a Ricoh Industries Ltd. (20), the color-curing composition A for molding, the color-curing composition B for molding, and the support-curing composition were respectively filled, and three-dimensional molded objects (artificial teeth) of Examples 1-2 and Comparative Examples 1-3 were fabricated based on the following division conditions and molding conditions.

[0092] <Split condition> As shown in Figures 2A and 2B, 3D data A was obtained by 3D scanning the actual tooth to be modeled, and 90% of that data B was created by reducing its width and height to 90%. Next, the centroids of 3D data A and 90% 3D data B in the horizontal direction (X,Y plane) were aligned, and 3D data C(AB) was created by removing the overlapping portion of 3D data A with 90% 3D data B using Boolean operations. Next, the 3D data C and 3D data B were sliced ​​and converted into bitmap (bmp) slice data, thereby obtaining slice data for the first part (part C) and the second part (part B).

[0093] Next, based on the slice data, the first part (part C) of Examples 1 and 2 and the first and second parts of Comparative Example 1 were treated with the molding color curing composition A from the curing composition set. Furthermore, based on the slice data, the second part (part B) of Example 1 and the first and second parts of Comparative Example 2 were treated with a 50:50 ratio of the above-mentioned curing composition set, specifically color curing composition A and color curing composition B. Furthermore, based on the slice data, the second part (part B) of Example 2 was treated with the molding color curing composition B from the curing composition set described above. Furthermore, based on the slice data, the first and second parts of Comparative Example 3 were treated with the molding color curing composition B from the curing composition set described above. Next, based on the following molding conditions, the three-dimensional object was fabricated using the molding apparatus shown in Figure 3 above.

[0094] <Formation Conditions> The material was ejected under the following conditions: resolution of 1200 dpi x 300 dpi, drop volume per drop (pL) as shown in Table 1 below, and printing speed of 420 mm / second. The material was cured by light irradiation using a UV-LED device for inkjet printers (device name: UV-LED module (single-pass water-cooled, manufactured by Ushio Inc.)). The distance between the print head and the light source was 200 mm. Curing occurs at a wavelength range corresponding to the UVA region of 1 W / cm². 2 So, 3J / cm 2 The material was cured under the specified light intensity conditions. The light intensity was measured in the UVA region using UV Power Puck® II (manufactured by EIT).

[0095] [Table 1]

[0096] Next, the aesthetics of each obtained three-dimensional model (artificial tooth) were evaluated as follows. The results are shown in Table 2. Photographs of the artificial teeth from Example 1 are shown in Figure 4, from Example 2 in Figure 5, from Comparative Example 1 in Figure 6, from Comparative Example 2 in Figure 7, and from Comparative Example 3 in Figure 8.

[0097] <Aesthetics> The aesthetics of each artificial tooth were evaluated based on visual observation of photographs obtained, according to the following criteria. [Evaluation Criteria] ○: As shown in Figures 4 and 5, the color of the cervical area (root portion) is darker, the color of the incisal edge is lighter, and the transparency is high, resulting in a natural color. ×: As shown in Figure 6, the overall transmittance is too high, and the internal holes are visible. Also, as shown in Figures 7 and 8, the cut ends (where they interlock) lack transparency.

[0098] Furthermore, using the above curable composition set, test specimens were prepared as follows, and the transmittance and L were measured. * a * b * The following measurements were taken. The results are shown in Table 2.

[0099] <Preparation of test specimens> Using the same color-curing composition for molding as in Examples 1-2 and Comparative Examples 1-3, and with the same dropper volume, test pieces measuring 20 mm in length, 20 mm in width, and 1 mm in thickness for measuring the first part were fabricated under the same molding conditions as in Examples 1-2 and Comparative Examples 1-3. Furthermore, using the same color-curing composition for molding as in Examples 1-2 and Comparative Examples 1-3, and with the same dropper volume, and under the same molding conditions as in Examples 1-2 and Comparative Examples 1-3, test pieces measuring 20 mm in length, 20 mm in width, and 1 mm in thickness for measuring the second area were fabricated.

[0100] <Method for measuring transmittance> The total light transmittance (T1) of the first part and the total light transmittance (T2) of the second part were measured using a DIRECT READING HAZEMETER (manufactured by Toyo Seiki Co., Ltd.) on the prepared test specimens for the first and second parts, and the difference in transmittance (T1-T2) was determined.

[0101] <L * a * b * Measurement method > Place 10 sheets of copy paper (MyPaper A4 size, manufactured by Ricoh Co., Ltd.) on a flat table, place the first or second part measurement test specimen prepared above on top, and measure the L of each test specimen using a spectrophotometer (eXact, manufactured by Xrite, condition: D50 / 2). * a * b * Measure three times and calculate the average value, L * value + a * value + b* The value was used, and ΔE was calculated using the following formula 1. [Formula 1] ΔE={(L2-L1) 2 +(b2-b1) 2 +(a2-a1) 2} 0.5 However, in the above formula 1, L1 is the L of the first part. * The value, L2 is the L of the second part. * The value, b1 is the b of the first part. * The value, b2 is the second part of b * The value, a1 is the a of the first part. * The value a2 is the a of the second part. * Represents a value.

[0102] [Table 2]

[0103] Examples of the present invention are as follows: <1> A method for manufacturing a three-dimensional object having parts colored in different colors, A division process that divides the 3D data of a three-dimensional object into at least two parts, A molding process in which, of the two parts after division, the first and second parts that are in contact with each other are colored in different colors, This is a method for manufacturing a three-dimensional object, characterized by including [a specific element]. <2> The first part is the outermost surface part of the three-dimensional object, <1> This is a method for manufacturing three-dimensional objects as described above. <3> The transmittance of the first part is higher than the transmittance of the second part, <1> from <2> This is a method for manufacturing a three-dimensional object as described in any of the following. <4> The difference (T1-T2) between the transmittance of the first area (T1) and the transmittance of the second area (T2) is 10% or more. <3> This is a method for manufacturing three-dimensional objects as described above. <5> L of the first part * a * b * L in color systems* value + a * value + b * The value is L of the second part. * a * b * L in color systems * value + a * value + b * The above, less than the value <1> from <4> This is a method for manufacturing a three-dimensional object as described in any of the following. <6> The ΔE represented by the following formula 1 is 10 or greater, <5> This is a method for manufacturing three-dimensional objects as described above. [Formula 1] ΔE={(L2-L1) 2 +(b2-b1) 2 +(a2-a1) 2} 0.5 However, in the above formula 1, L1 is the L of the first part. * The value, L2 is the L of the second part. * The value, b1 is the b of the first part. * The value, b2 is the second part of b * The value, a1 is the a of the first part. * The value a2 is the a of the second part. * Represents a value. <7> The molding is performed by an inkjet method. <1> from <6> This is a method for manufacturing a three-dimensional object as described in any of the following. <8> The molding process in at least one of the XY and Z directions includes dithering. <1> from <7> This is a method for manufacturing a three-dimensional object as described in any of the following. <9> The curing composition used in the molding process contains a radical polymerizable compound and a colorant or a hard solid component, <1> from <8> This is a method for manufacturing a three-dimensional object as described in any of the following. <10> The aforementioned three-dimensional object is tooth-shaped, The portion near the surface has at least one area that becomes thicker from the cervical area towards the incisal edge, <1> from <9> This is a method for manufacturing a three-dimensional object as described in any of the following.

[0104] The aforementioned <1> from <10> According to the method for manufacturing a three-dimensional object described in any of the above, the conventional problems can be solved and the objectives of the present invention can be achieved. [Explanation of symbols]

[0105] 1. Model part forming material 2. Support part forming material 10 Model Section 20 Support Department 30. A device for creating three-dimensional objects. 31 Head Unit 32 Head Units 33 Ultraviolet irradiation machine 34 rollers 35 Carriage 36 circuit boards 37 stages [Prior art documents] [Patent Documents]

[0106] [Patent Document 1] Patent No. 6949024

Claims

1. A method for manufacturing a tooth-shaped three-dimensional object having parts colored in different colors, A division process that divides the 3D data of a three-dimensional object into at least two parts, A molding process in which, of the two parts after division, the first part and the second part that are in contact with each other are colored in different colors, Includes, The first part is the outermost surface part of the three-dimensional object, and the transmittance of the first part is higher than the transmittance of the second part. A method for manufacturing a three-dimensional object, characterized in that the first portion has at least one portion that becomes thicker from the cervical portion toward the incisal edge.

2. The method for manufacturing a three-dimensional object according to claim 1, wherein the difference (T1-T2) between the transmittance of the first part (T1) and the transmittance of the second part (T2) is 10% or more.

3. The L value of the first part ＊ a ＊ b ＊ The L value in the color system ＊ value + a ＊ value + b ＊ The L value of the second part ＊ a ＊ b ＊ The L value in the color system ＊ value + a ＊ value + b ＊ The method for manufacturing a three-dimensional shaped object according to any one of claims 1 to 2, wherein the values are smaller than the corresponding values of the second part.

4. A method for manufacturing a three-dimensional object according to claim 3, wherein ΔE, represented by the following formula 1, is 10 or more. [Formula 1] ΔE={(L2-L1) ２ +(b2-b1) ２ +(a2-a1) ２ } ０．５ However, in formula 1 above, L1 represents the L* value of the first part, L2 represents the L* value of the second part, b1 represents the b* value of the first part, b2 represents the b* value of the second part, a1 represents the a* value of the first part, and a2 represents the a* value of the second part.

5. A method for manufacturing a three-dimensional object according to any one of claims 1 to 4, wherein the molding is performed by an inkjet method.

6. A method for manufacturing a three-dimensional object according to any one of claims 1 to 5, wherein the molding in at least one of the XY direction and the Z direction includes a dithering process.

7. A method for producing a three-dimensional object according to any one of claims 1 to 6, wherein the curing composition used for the molding contains a radical polymerizable compound and a colorant or a hard solid component.

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