Molding method and molding device

Abstract

To solve the problem of printing accuracy deterioration in the colored area of a three-dimensional modeling object in the case of modeling a colored three-dimensional modeling object.SOLUTION: A method for modeling a colored three-dimensional modeling object includes a dispensing process C in which an active energy ray curable coloring ink is dispensed by an inkjet method, a curing process C in which the dispensed coloring ink is cured by irradiating an active energy ray, a dispensing process B in which an active energy ray curable base ink is dispensed by an inkjet method, and a curing process B in which the dispensed base ink is cured by irradiating an active energy ray. The colored three-dimensional modeling object is formed by stacking plural layers by repeating the dispensing process C and the curing process C sequentially and repeating the dispensing process B and the curing process B sequentially. The landing area C formed by the ejected colored ink landing on the object is smaller than the landing area B formed by the ejected base ink landing on the object.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a molding method and a molding apparatus. [Background technology]

[0002] A technology called additive manufacturing (AM) is known as a technique for forming three-dimensional objects. This technology calculates the cross-sectional shape of a thin slice in the stacking direction, and forms and stacks each layer according to that shape to form a three-dimensional object. In recent years, among additive manufacturing technologies, a material jetting method has been attracting attention. This method uses an inkjet head to deposit an active energy ray-curable composition at a desired location, and then cures the deposited active energy ray-curable composition using a light irradiation device or the like to form a three-dimensional object.

[0003] The material jetting method is mainly used for prototyping purposes, and the cured product is required to have various properties such as stretchability, impact resistance, heat resistance, etc. A known method for improving these properties is to add a solid component such as a filler to the active energy ray-curable composition.

[0004] It is also possible to prepare a colored cured product by adding a coloring material such as a dye or a pigment to the active energy ray-curable composition.

[0005] Patent Document 1 discloses a three-dimensional object forming apparatus including a forming unit that forms a decorative layer by stacking layers including regions formed with colored inks or clear inks to form a three-dimensional object, the forming unit comparing overlapping regions in the entire decorative layer, where adjacent layers formed with the same ink overlap, with non-overlapping regions other than the overlapping regions formed with the same ink, where adjacent layers formed with the same ink do not overlap, and forming the overlapping regions so that the ink ejection volume per unit volume is smaller than that of the non-overlapping regions. This disclosure provides a three-dimensional object that does not have color defects in the colored regions, such as problems with overlapping colored decorative portions of adjacent upper and lower layers in the stacking direction, where the overlapping portions appear darker than the desired color tone, and problems with separation between the colored decorative portions of each layer, where the colored decorative portions of the upper layer appear to be missing color at the boundary between the colored decorative portion of the lower layer. Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a colored three-dimensional object is formed by ejecting active energy ray-curable ink using an inkjet method, there is a problem that printing accuracy in the colored areas of the three-dimensional object decreases. [Means for solving the problem]

[0007] The present invention relates to a modeling method for forming a colored three-dimensional object by stacking a plurality of layers, the method including: a discharging step C of discharging active energy ray-curable colored ink by an inkjet system; a curing step C of irradiating the discharged colored ink with active energy rays to cure it; a discharging step B of discharging active energy ray-curable base ink by an inkjet system; and a curing step B of irradiating the discharged base ink with active energy rays to cure it; the method is characterized in that the discharging step C and the curing step C are sequentially repeated, and the discharging step B and the curing step B are sequentially repeated, and the method is characterized in that the landing area C formed by the landing of the discharged colored ink is smaller than the landing area B formed by the landing of the discharged base ink. [Effects of the Invention]

[0008] According to the present invention, when a colored three-dimensional object is formed by ejecting an active energy ray-curable ink using an inkjet method, a modeling method can be provided that can produce a three-dimensional object with excellent printing accuracy in the colored areas. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of a conventional process for producing a colored three-dimensional object. [Figure 2] FIG. 2 is a schematic diagram showing an example of the process of the present invention for producing a colored three-dimensional object. [Figure 3] FIG. 3 is a schematic view showing a molding apparatus according to one embodiment of the present invention. [Figure 4] FIG. 4 is a photograph of a three-dimensional object having a two-dimensional code formed in Example 1. [Figure 5] FIG. 5 is a photograph of a three-dimensional object having a two-dimensional code formed in Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Molding method The modeling method of the present invention includes a discharge step C of discharging active energy ray-curable colored ink (hereinafter also referred to as "colored ink") using an inkjet system, a curing step C of irradiating the discharged colored ink with active energy rays to cure it, a discharge step B of discharging active energy ray-curable base ink (hereinafter also referred to as "base ink") using an inkjet system, and a curing step B of irradiating the discharged base ink with active energy rays to cure it. The modeling method of the present invention may also include other steps as necessary, such as a discharge step S of discharging active energy ray-curable support ink (hereinafter also referred to as "support ink") using an inkjet system, and a curing step S of irradiating the discharged support ink with active energy rays to cure it. Note that the colored ink discharged in the discharge step C lands to form a landing area C, the base ink discharged in the discharge step B lands to form a landing area B, and the support ink discharged in the discharge step S lands to form a landing area S. Furthermore, in the modeling method of the present invention, the discharging step C and the curing step C are sequentially repeated, and the discharging step B and the curing step B are sequentially repeated. This results in the formation of a colored three-dimensional object formed by stacking multiple layers. Note that the sequential repetition of the discharging step C and the curing step C (hereinafter also referred to as "repeated step C") and the sequential repetition of the discharging step B and the curing step B (hereinafter also referred to as "repeated step B") may be performed independently, or some steps in the repeated step C and the repeated step B (for example, the curing step C and the curing step B) may be performed simultaneously.

[0011] In the present disclosure, the term "active energy ray curable" refers to the property of curing to form a cured product upon irradiation with active energy rays. Furthermore, "curing" refers to the formation of a polymer, but is not limited to solidification, and also includes thickening and both solidification and thickening. Furthermore, the term "cured product" refers to a polymer, but is not limited to solids, and also includes thickened products and mixtures of solids and thickened products. In the present disclosure, the above-mentioned "active energy ray-curable base ink" refers to an ink that forms the shape of a desired three-dimensional object (hereinafter also referred to as "model portion") upon curing. Furthermore, the term "active energy ray-curable colored ink" refers to an ink that forms a colored region in the model portion that exhibits a color different from the color of the region formed by the base ink upon curing. Furthermore, the term "active energy ray-curable support ink" refers to an ink that forms the shape of a support portion that supports the model portion upon curing. In this disclosure, the above-mentioned "landing area C" refers to the area formed by the landing of colored ink ejected onto one voxel. Furthermore, "landing area B" refers to the area formed by the landing of base ink ejected onto one voxel. "Landing area S" refers to the area formed by the landing of support ink ejected onto one voxel. In the present disclosure, the above-mentioned "layer" refers to an area where multiple landing areas C and landing areas B located at approximately the same height are gathered together, and represents, for example, an area where multiple landing areas C and landing areas B are gathered together, which are formed between a predetermined operation (e.g., the formation of landing area C or a smoothing process (roller processing, etc.) described below) being performed at a predetermined location P and the next predetermined operation being performed at a predetermined location P' (a location that differs from the predetermined location P only in its vertical position).

[0012] In the modeling method of the present invention, the landing area C formed by the landing of the ejected colored ink is smaller than the landing area B formed by the landing of the ejected base ink. Having landing area C smaller than landing area B allows for the production of a three-dimensional object with excellent printing accuracy in the colored area. In this disclosure, "excellent printing accuracy in the colored area" refers to high visibility of what is represented by the colored area. However, in this disclosure, "visibility" refers to the property of being easily recognized or distinguished using the action of light, and is not limited to being easily recognized visually, but also includes the property of being easily distinguished using devices such as optical instruments. Even if a colored area cannot be distinguished using devices such as optical instruments, it is considered to have "excellent printing accuracy in the colored area" if it has the property of being easily recognized visually compared to colored areas produced by conventional methods.

[0013] The reason why a three-dimensional object with excellent printing accuracy in the colored area can be manufactured by making landing area C smaller than landing area B will be explained with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing an example of a conventional process for manufacturing a colored three-dimensional object. Figure 2 is a schematic diagram showing an example of a process of the present invention for manufacturing a colored three-dimensional object. When manufacturing a three-dimensional object using the material jetting method, it is necessary to form the shape of the three-dimensional object in the height direction, so the amount of ink ejected per unit area (in other words, the amount of ink droplets ejected) is greater than when forming a two-dimensional image using the inkjet method. Therefore, when manufacturing a colored three-dimensional object using colored inks and base inks, if the ejection amounts of the colored inks and base inks are approximately equal as in the conventional method, the area formed by bleeding in the landing area C formed by the colored ink after landing is likely to become large, posing a problem of reduced printing accuracy in the colored area. Specifically, as shown in FIG. 1 as an example, when color ink droplets d1 are ejected onto the uppermost layer L4 of multiple layers L1 to L4 formed on a stage 37 so that the droplet volume C of the color ink droplets d1 is approximately equal to the droplet volume B of the base ink droplets d2, landing areas C (D1) and B (D2) of approximately the same area are formed. However, a large bleed area E is created at the edge of landing area C (D1), making it difficult to manufacture a three-dimensional object with excellent printing accuracy in the colored areas. On the other hand, when a colored three-dimensional object is produced using the modeling method of the present invention in which landing area C is smaller than landing area B, even if bleeding occurs in landing area C formed by the colored ink after landing, the area caused by bleeding is small, and printing accuracy in the colored area is improved. Specifically, as shown in FIG. 2 as an example, when color ink droplets d1 are ejected onto the uppermost layer L4 of multiple layers L1 to L4 formed on the stage 37 so that the droplet volume C of the color ink droplets d1 is smaller than the droplet volume B of the base ink droplets d2, a landing region C (D1) having a smaller area than the landing region B (D2) is formed, and the occurrence of bleeding regions at the edges of the landing region C (D1) is also suppressed, making it possible to produce a three-dimensional object with excellent printing precision in the colored regions. As a result, even if image information having a fine shape, such as a two-dimensional code, is applied to a three-dimensional object as a colored area, the printing accuracy in the colored area is excellent, making it possible to manufacture a three-dimensional object with a two-dimensional code that has excellent reading accuracy. In the present disclosure, whether landing area C is smaller than landing area B is determined based on area. Specifically, the area of ​​the area formed by the landing of colored ink ejected onto one voxel when viewed in plan from the ejection direction is defined as the area of ​​landing area C, and the area of ​​the area formed by the landing of base ink ejected onto one voxel when viewed in plan from the ejection direction is defined as the area of ​​landing area B, and it is determined whether the area of ​​landing area C is smaller than the area of ​​landing area B. In addition, in this disclosure, the term "amount of droplet" refers to the volume of ink ejected into one voxel.

[0014] As described above, the area of ​​landing region C is smaller than the area of ​​landing region B. Specifically, the area of ​​landing region C is preferably 50% or less of the area of ​​landing region B, more preferably 40% or less, and even more preferably 30% or less. By making the area of ​​landing region C 50% or less, printing accuracy in the colored region is further improved. Furthermore, the area of ​​landing region C is preferably 5% or more of the area of ​​landing region B.

[0015] As described above, it is preferable that the droplet volume C of the ejected color ink is less than the droplet volume B of the ejected base ink. Specifically, it is more preferable that the droplet volume C of the color ink is 70% by volume or less of the droplet volume B of the ejected base ink, and even more preferable that it is 50% by volume or less. By having it be 70% by volume or less, printing accuracy in the colored area is further improved. Furthermore, it is preferable that the droplet volume C of the color ink is 10% by volume or more of the droplet volume B of the ejected base ink.

[0016] Furthermore, the modeling method of the present invention is preferably performed so that there are overlapping areas within the layer where impact area C and impact area B exist (so that the colored area is an area where not only impact area C but also impact area B coexists). Having overlapping areas within the layer where impact area C and impact area B exist results in impact area B being distributed throughout the entire area of ​​the three-dimensionally molded object. This improves the strength and modeling accuracy of the three-dimensionally molded object compared to when impact area C and impact area B do not overlap within the layer (when the colored area is formed only by impact area C, which is smaller than impact area B). Note that when the colored area is large (for example, when the colored area is a solid image), if impact area C and impact area B do not overlap within the layer, the strength and modeling accuracy of the three-dimensionally molded object are more likely to decrease. Therefore, the effect of having overlapping areas within the layer where impact area C and impact area B exist becomes more pronounced. Furthermore, it is more preferable that the shaping method of the present invention be carried out so as to have an area within the layer where landing area B overlaps landing area C. By having an area within the layer where landing area B overlaps landing area C, even if a smoothing step (roller processing, etc.) described below is carried out after landing area B is formed, the smoothing means (roller, etc.) does not come into direct contact with landing area C, which further provides the effect of suppressing a decrease in printing accuracy in the colored area due to, for example, landing area C being stretched by the smoothing means (roller, etc.). Specifically, as an example shown in Figure 2, droplets d1 of colored ink are ejected onto the top layer L4 of multiple layers L1 to L4 formed on stage 37, and then droplets d2 of base ink are further ejected onto the area where the droplets d1 of colored ink have been ejected, thereby forming an area within the layer where landing area C (D1) and landing area B (D2) overlap.

[0017] (1) Discharge process C The ejection step C is a step of ejecting active energy ray-curable color ink by an inkjet method. Specifically, the color ink is ejected by an inkjet method onto a stage having an elevating function or onto a layer formed on the stage, and the ejected color ink forms landing areas C. Note that the landing areas C may gather to form a liquid film.

[0018] (i) Active energy ray curable color ink The active energy ray-curable color ink contains a radical polymerizable compound and a colorant. The color ink may also contain a polymerization initiator, a surfactant, a polymerization inhibitor, a dispersant, and other components, as necessary.

[0019] (A) Radical polymerizable compound The term "radical polymerizable compound" refers to a compound capable of forming a polymer by radical polymerization, and is typically a compound as a monomer unit 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 compounds may be used alone or in combination of two or more. The radically polymerizable monofunctional monomer, the radically polymerizable polyfunctional monomer, and the radically polymerizable oligomer are all monomer units of a cured product obtained by radical polymerization using active energy rays. In other words, in the present invention, a "radically polymerizable monomer" refers to a monomer molecule having one or more radically polymerizable functional groups, and a "radically polymerizable oligomer" refers to an oligomer molecule having one or more radically polymerizable functional groups. An "oligomer" refers to a molecule having structural units derived from a small number of monomers. The number of structural units may vary depending on the structure of the monomer and the application of the oligomer, but is typically preferably 2 to 20.

[0020] When a radically polymerizable compound is used as the polymerizable compound, the increase in viscosity is suppressed and the polymerization rate can be improved compared to when a cationically polymerizable compound is used, and therefore the radically polymerizable compound can be suitably used in the inkjet method. Furthermore, by using a radically polymerizable monomer as the radically polymerizable compound, it is possible to further prevent the viscosity of the color ink from increasing. Furthermore, by using a radically polymerizable monofunctional monomer as the radically polymerizable compound, it is possible to further prevent the viscosity of the color ink from increasing. Furthermore, by using a radically polymerizable oligomer as the radically polymerizable compound, it is possible to reduce cure shrinkage of the cured product and also improve the stretchability and toughness of the cured product.

[0021] 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 alone or in combination of two or more.

[0022] Examples of radically polymerizable polyfunctional monomers include bifunctional monomers, trifunctional or higher functional monomers, etc. These may be used alone or in combination of two or more.

[0023] 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 hydroxypivalic acid ester di(meth)acrylate, hydroxypivalic acid neopentyl glycol ester di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexamethylpropional ... Examples of such diesters include 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, tricyclodecane dimethanol di(meth)acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol ester di(meth)acrylate, propoxylated dipentyl glycol di(meth)acrylate, ethoxy-modified bisphenol A di(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, and polyethylene glycol 400 di(meth)acrylate. These may be used alone or in combination of two or more.

[0024] Examples of trifunctional or higher radical polymerizable polyfunctional monomers 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, ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate, ) acrylate, 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, penta(meth)acrylate ester, etc. These may be used alone or in combination of two or more.

[0025] The radical polymerizable oligomer is preferably, for example, a monofunctional to hexafunctional monomer, more preferably a difunctional to trifunctional monomer, which may be used alone or in combination of two or more. Furthermore, by using a radical polymerizable oligomer having a urethane group, interactions occur between side chains in the polymer, improving the toughness of the cured product. Furthermore, the radical polymerizable oligomer having a urethane group is more preferably a urethane acrylate oligomer.

[0026] As the radical polymerizable oligomer, commercially available products 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 Industry Co., Ltd.) and CN983NS (aliphatic urethane acrylate oligomer, number of polymerizable functional groups: 2, manufactured by Sartomer Co., Ltd.). These may be used alone or in combination of two or more.

[0027] As described above, examples of the radical polymerizable compound include acrylic monomers, methacrylic monomers, and vinyl carboxylic acid ester monomers, but it is preferable to use acrylic monomers. Acrylic monomers can suppress the viscosity of the colored ink from increasing and can improve the polymerization rate, so they are suitable for use in inkjet printing. When using a radical polymerizable monofunctional monomer other than an acrylic monomer or an epoxy monomer, it is preferable to use it in combination with the acrylic monomer. Examples of epoxy monomers include bis(3,4-epoxycyclohexyl) and bisphenol A diglycidyl ether. When using an epoxy monomer in combination with an acrylic monomer, it is preferable to also use an oxetane monomer in combination.

[0028] The content of the radical polymerizable compound relative to the mass of the color ink is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, even more preferably 70.0% by mass or more, and particularly preferably 80.0% by mass or more, and is preferably 99.0% by mass or less, more preferably 95.0% by mass or less.

[0029] The content of the radical polymerizable monofunctional monomer is preferably 30.0% by mass or more, more preferably 40.0% by mass or more, relative to the mass of the color ink, and is preferably 99.0% by mass or less, more preferably 95.0% by mass or less.

[0030] The content of the radical polymerizable polyfunctional monomer is preferably 10.0% by mass or more, and more preferably 40.0% by mass or less, and more preferably 30.0% by mass or less, relative to the mass of the color ink.

[0031] The content of the radical polymerizable oligomer is preferably 1.0% by mass or more, more preferably 10.0% by mass or more, relative to the mass of the color ink, and is preferably 40.0% by mass or less, more preferably 30.0% by mass or less.

[0032] (B) Color material The coloring material is contained in the color ink to form the above-mentioned colored region. The coloring material is preferably a dye or pigment that can be dissolved or stably dispersed in the color ink, and more preferably a pigment from the viewpoint of durability and safety. Note that in the present disclosure, the pigment is functionally distinguished from the hard solid component described below, and the hard solid component is not included in the pigment.

[0033] The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used as the pigment. Examples of inorganic pigments that can be used include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method. Examples of 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, and quinophthalone pigments), dye chelates (e.g., basic dye chelates, acid dye chelates), nitro pigments, nitroso pigments, and aniline black. The volume average particle diameter of the pigment is preferably 10 nm or more and 1,000 nm or less from the viewpoints of dispersion stability of the pigment and image density in the colored region. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0034] The dyes that can be used include acid dyes, direct dyes, reactive dyes, and basic dyes, which may be used alone or in combination of two or more.

[0035] The content of the colorant is preferably 0.1% by mass or more, and more preferably 0.1% by mass or more and 10.0% by mass or less, based on the mass of the color ink. By having the content of the colorant be 0.1% by mass or more, it is possible to sufficiently improve the image density in the colored region even in the modeling method of the present disclosure, which ejects a smaller amount of color ink compared to general modeling methods.

[0036] (C) Polymerization initiator The polymerization initiator may be any substance that generates radicals or cations when irradiated with active energy rays such as light. Examples of active energy rays include visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays. The polymerization initiator may be used alone or in combination with two or more different types. The content of the polymerization initiator 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 mass of the colored ink. Examples of radical photopolymerization initiators include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p,p'-chlorobenzophenone, p,p-bisdiethylaminobenzophenone, Michler's ketone, benzil, 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-hydroxycyclohexyl phenyl ketone, azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide. These may be used alone or in combination of two or more. Examples of the cationic photopolymerization initiator include commercially available products such as UVI-6950, UVI-6970, UVI-6974, and UVI-6990 (all manufactured by Union Carbide Corporation), Adeka Optomer SP-150, SP-151, SP-170, and SP-172 (all manufactured by Asahi Denka Kogyo Co., Ltd.), and Irgacure 261 (all manufactured by Ciba Specialty Chemicals), CI-2481, CI-2624, CI-2639, CI-2064 (all manufactured by Nippon Soda Co., Ltd.), CD-1010, CD-1011, CD-1012 (all manufactured by Sartomer), DTS-102, DTS-103, NAT-103, NDS-103, TPS-103, MDS-103, MPI-103, BBI-103 (all manufactured by Midori Chemical Co., Ltd.), PCI-061T, PCI-062T, PCI-020T, PCI-022T (all manufactured by Nippon Kayaku Co., Ltd.). These may be used alone or in combination of two or more.

[0037] (D) Surfactant The surfactant is preferably, for example, a compound having a molecular weight of 200 to 5000. Specific examples include PEG-type nonionic surfactants (e.g., 1-40 mol adduct of nonylphenol with ethylene oxide (hereinafter abbreviated as EO), stearic acid adduct of 1-40 mol of EO, etc.), polyhydric alcohol-type nonionic surfactants (e.g., sorbitan palmitate monoester, sorbitan stearate monoester, sorbitan stearate triester, etc.), fluorine-containing surfactants (e.g., 1-50 mol adduct of perfluoroalkyl EO, perfluoroalkyl carboxylate, perfluoroalkyl betaine, etc.), modified silicone oils (e.g., polyether-modified silicone oil, (meth)acrylate-modified silicone oil, etc.), etc. These may be used alone or in combination of two or more.

[0038] (E) 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 [dilauryl thiodipropionate, etc.], phosphorus compounds [triphenyl phosphite, etc.], amine compounds [phenothiazine, etc.], etc. These may be used alone or in combination of two or more.

[0039] (F) Dispersant The dispersant is an additive that adsorbs to the surface of solid components such as pigments, thereby stably dispersing the solid components in the colored ink. Any known dispersant can be used as the dispersant.

[0040] (G) Other ingredients Examples of other components include organic solvents, water, and hard solid components.

[0041] The color ink may contain an organic solvent, but preferably does not contain one if possible. A composition that does not contain organic solvents, especially volatile organic solvents (VOC (Volatile Organic Compounds)-free), enhances the safety of the area where the composition is handled and also helps 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, "free of" organic solvents means that they are substantially free (for example, not to the extent that the properties of the organic solvent affect the color ink), and the content of organic solvents is preferably less than 0.1% by mass relative to the mass of the color ink.

[0042] The color ink may contain water, but preferably does not contain water if possible. Furthermore, "does not contain" water means that the ink is substantially free of water (for example, not to the extent that the properties of water would affect the color ink), and the content is preferably less than 1.0% by mass relative to the mass of the color ink. By keeping the water content below a certain amount, it is possible to suppress a decrease in curing speed, a decrease in curing strength, an increase in water absorption, and a decrease in separability from the support portion formed by the support ink described below.

[0043] The color ink may contain a hard solid component, as described below, but preferably does not contain one if possible. As described above, the color ink preferably contains a pigment as a coloring material, which is a solid component. However, if a hard solid component is further contained as an additional solid component, it becomes necessary to consider the conditions for stably dispersing both the pigment and the hard solid component in the color ink, which increases the difficulty of formulating and manufacturing the color ink. Furthermore, "not containing" a hard solid component means that the hard solid component is substantially not contained (for example, not contained to the extent that the properties of the hard solid component would affect the color ink), and the content is preferably less than 0.1% by mass relative to the mass of the color ink. If the color inks do not contain hard solid components, a decrease in strength is expected in the regions (colored regions) of the three-dimensional object formed with the color inks, but as described above, by performing the modeling method so that there are regions within the layer where impact region C and impact region B overlap, impact region B derived from the base ink containing hard solid components is arranged throughout the entire three-dimensional object. This makes it possible to achieve both improved dispersion stability of the color inks and suppressed strength reduction in the colored regions.

[0044] (H) Physical properties of colored ink Colored inks suitable for use in inkjet printing preferably have low viscosity, taking into account factors such as ejection properties from nozzles. Therefore, in one embodiment, the viscosity of the colored ink of the present invention is preferably 1000 mPa·s or less, more preferably 200 mPa·s or less, and even more preferably 150 mPa·s or less, in a 25°C environment. Furthermore, from the viewpoints of ejection properties and modeling accuracy, the viscosity is preferably 9 mPa·s or more in a 25°C environment. During modeling, the viscosity of the colored ink can be adjusted by adjusting the temperature of the inkjet head or ink flow path. The viscosity can be measured by a conventional method, for example, the method described in JIS Z 8803. Alternatively, the viscosity can be measured using a cone-plate rotational viscometer, VISCOMETER TVE-22L, manufactured by Toki Sangyo Co., Ltd., with a cone rotor (1°34' x R24), at a rotation speed of 50 rpm, and with the temperature of the constant-temperature circulating water appropriately set in the range of 20°C to 65°C. A VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

[0045] Furthermore, in view of ejection stability, modeling accuracy, etc., the color ink that can be used in inkjet applications preferably has a surface tension in the range of 20 to 40 mN / m in an environment of 25° C. Accordingly, in one embodiment, the color ink of the present invention has a surface tension of 20 to 40 mN / m in an environment of 25° C. The surface tension can be measured by a conventional method, such as the plate method, ring method, pendant drop method, or the like.

[0046] (I) Colored ink container A color ink storage container refers to a container in which color ink is stored. A container containing color ink can be used as a cartridge or bottle, which eliminates the need to directly touch the color ink during transportation, replacement, and other operations, preventing staining of fingers and clothing. It also prevents foreign matter such as dust from getting mixed into the color ink. The shape, size, material, and other aspects of the container itself are not particularly limited as long as they are appropriate for the intended use and usage, but it is desirable that the material be a light-blocking material that does not transmit light, or that the container be covered with a light-blocking sheet or the like.

[0047] (2) Curing process C The curing step C is a step of curing the ejected color ink by irradiating it with active energy rays. Specifically, the landing area C formed by the landing of the ejected color ink is irradiated with active energy rays according to the polymerization initiator contained in the color ink.

[0048] The active energy ray used to cure the colored ink is preferably light, and particularly ultraviolet light with a wavelength of 220 nm to 400 nm. In addition to ultraviolet light, electron beams, α-rays, β-rays, γ-rays, X-rays, and other light sources that can provide the energy necessary to promote the polymerization reaction of the polymerizable components in the composition are not particularly limited. When a particularly high-energy light source is used, the polymerization reaction can proceed without the use of a polymerization initiator. Furthermore, in the case of ultraviolet irradiation, mercury-free light sources are strongly desired from the perspective of environmental protection, and replacement with GaN-based semiconductor ultraviolet light-emitting devices is extremely useful from both an industrial and environmental perspective. Furthermore, ultraviolet light-emitting diodes (UV-LEDs) and ultraviolet laser diodes (UV-LDs) are preferred as ultraviolet light sources due to their compact size, long life, high efficiency, and low cost.

[0049] (3) Discharge process B The ejection step B is a step of ejecting an actinic ray-curable base ink by an inkjet method. Specifically, the base ink is ejected by an inkjet method onto a stage having an elevation function, onto a layer formed on the stage, or onto landing areas C formed by the landing of colored inks formed on these, and the ejected base ink forms landing areas B. Note that the landing areas B may gather to form a liquid film.

[0050] (i) Active energy ray curable base ink The active energy ray-curable base ink contains a radical polymerizable compound and a hard solid component. The base ink may also contain a polymerization initiator, a surfactant, a polymerization inhibitor, a dispersant, and other components as necessary. The various components contained in the base ink will be described below, but the radical polymerizable compound, polymerization initiator, surfactant, polymerization inhibitor, and dispersant can be used in the same manner as in the colored inks described above, and therefore their description will be omitted. Furthermore, the physical properties of the base ink are preferably similar to those of the colored inks, and the container for storing the base ink is preferably similar to that of the colored inks, and therefore their description will also be omitted.

[0051] (A) Hard solid component The hard solid component is contained to improve the elastic modulus, strength, impact resistance, etc. of the cured product of the base ink. In the present disclosure, "hard" refers to the property of being resistant to deformation due to external stress. Those skilled in the art can determine whether a material is hard based on criteria known in the art, such as 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, according to JIS K 7161, JIS K 7171, ISO 14577, etc. In the present disclosure, the term "solid component" refers to a component that can maintain a solid state in a liquid such as ink. The solid component is preferably in the form of particles in the liquid. Furthermore, the solid component is preferably in a dispersed state in the liquid. In the present disclosure, the hard solid component is functionally distinct from the above-mentioned coloring material, and for example, a pigment that is a coloring material of the solid component is not included in the hard solid component.

[0052] Examples of hard solid components 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.

[0053] In addition, it is preferable to use hard solid components such as glass, silica, and alumina that have hydroxyl groups on the surface thereof, which have been surface-modified using a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include vinyl methoxysilane, vinyl ethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, styryl p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl methyl dimethoxysilane, N-2-(aminoethyl)-3-aminopropyl methyl dimethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-triethoxy Examples include silyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, etc. These may be used alone 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.

[0054] The content of the hard solid component is preferably 0.5% by volume or more and 40.0% by volume or less, and more preferably 1.0% by volume or more and 20.0% by volume or less, relative to the volume of the base ink. By having the content of the hard solid component be 0.5% by volume or more relative to the volume of the base ink, the characteristics of the hard solid component can be better reflected in the three-dimensional object. Furthermore, by having the content of the hard solid component be 40.0% by volume or less relative to the volume of the base ink, the three-dimensional object can be prevented from becoming brittle.

[0055] The shape of the hard solid component is not particularly limited, and may be spherical, rod-like, or irregular, and may be hollow particles, porous particles, core-shell structure particles, or the like.

[0056] The volume average particle size of the hard solid component is preferably 10 nm or more and 1000 nm or less, and more preferably 120 nm or more and 300 nm or less. If the volume-average particle size of the hard solid component is 10 nm or more, the characteristics of the hard solid component can be fully reflected in the three-dimensional object. Furthermore, if the volume-average particle size is 1000 nm or less, the ejection stability by the inkjet method can be improved. Furthermore, considering the dispersion stability of the hard solid component in the base ink, a volume-average particle size of 300 nm or less is more preferable.

[0057] (B) Other ingredients Other components include, for example, organic solvents, water, coloring materials, etc. Note that the organic solvents and water are the same as those in the colored inks, so a description of these will be omitted.

[0058] The base ink may contain a pigment, which is the coloring material of the solid component described above, but it is preferable not to contain it if possible. As described above, the base ink contains a hard solid component, but if it further contains a pigment as an additional solid component, it becomes necessary to consider the conditions for stably dispersing both the pigment and the hard solid component in the base ink, which increases the difficulty of formulating and manufacturing the base ink. Furthermore, "not containing" a pigment means that it is substantially not contained (for example, the pigment is not contained to the extent that it affects the color tone of the base ink), and it is preferable that the content be less than 0.1% by mass of the base ink.

[0059] (4) Curing process B The curing step B is a step of irradiating the discharged base ink with active energy rays to cure it. Specifically, the landing area B formed by the discharged base ink is irradiated with active energy rays according to the polymerization initiator contained in the base ink. The active energy rays used to cure the base ink are the same as those used to cure the colored inks.

[0060] (5) Discharge process S The ejection step S is a step of ejecting an active energy ray-curable support ink by an inkjet method. Specifically, the support ink is ejected by an inkjet method onto a stage having an elevation function or onto a layer formed on the stage, and the ejected support ink forms a landing area S. Note that the landing areas S may gather to form a liquid film.

[0061] It is preferable that the discharging step S is performed in the same scan as the discharging step C, and that the discharging step B is performed in the scan after the discharging steps C and S. Generally, the discharging of the ink that forms the model portion and the ink that forms the support portion are preferably performed in different scans from the viewpoint of clearly forming the interface between the model portion and the support portion, and at least two scans have been performed. On the other hand, in the modeling method of the present invention, colored inks and base inks are used as the inks that form the model portion, and therefore the number of types of ink used increases compared to conventional manufacturing methods. However, because there are few or no cases where the landing area C, which is the area formed by the colored ink, and the landing area S, which is the area formed by the support ink, directly contact each other to form an interface (for example, as shown in FIG. 2, because the landing area B overlaps with the landing area C), the discharging step C and the discharging step S may be performed in the same scan. Therefore, in the modeling method of the present invention, although the number of types of inks that form the model portion increases compared to conventional methods, the number of scans during modeling can be the same as conventional methods, and productivity can be maintained.

[0062] (i) Active energy ray curable support ink The active energy ray curable support ink has the property of being disintegrable when the cured support ink is subjected to a treatment such as adding water, and the support portion can be easily removed from the model portion after molding. As the support ink, any known ink can be used as appropriate, and for example, the support ink disclosed in JP-A-2018-70731 can be used.

[0063] (6) Curing process S The curing step S is a step of irradiating the ejected support ink with active energy rays to cure it. Specifically, the landing area S formed by the impact of the ejected support ink is irradiated with active energy rays according to the polymerization initiator contained in the support ink. The active energy rays used to cure the support ink are the same as those used to cure the colored inks.

[0064] 2. Molding equipment The modeling apparatus of the present invention is an apparatus for executing the above-described modeling method, and includes a discharge means C that discharges active energy ray-curable colored inks by inkjet printing, a curing means C that irradiates the discharged colored inks with active energy rays to cure them, a discharge means B that discharges active energy ray-curable base inks by inkjet printing, and a curing means B that irradiates the discharged base ink with active energy rays to cure them. The modeling apparatus of the present invention may also include other means as necessary, such as a discharge means S that discharges active energy ray-curable support ink by inkjet printing, and a curing means S that irradiates the discharged support ink with active energy rays to cure them. The colored inks discharged by the discharge means C land to form landing area C, the base inks discharged by the discharge means B land to form landing area B, and the support inks discharged by the discharge means S land to form landing area S. Furthermore, the modeling apparatus of the present invention sequentially repeats discharging by discharging means C and curing by curing means C, and sequentially repeats discharging by discharging means B and curing by curing means B. This results in the formation of a colored three-dimensional object formed by stacking multiple layers. Note that the sequential repetition of discharging by discharging means C and curing by curing means C (hereinafter also referred to as "repeated step C") and the sequential repetition of discharging by discharging means B and curing by curing means B (hereinafter also referred to as "repeated step B") may be performed by independent means, or some of the means used in repetitive step C and repetitive step B (for example, curing means C and curing means B) may be performed by the same means.

[0065] An example of a modeling apparatus will be described in detail below with reference to FIG. 3. FIG. 3 is a schematic diagram showing a modeling apparatus according to one embodiment of the present invention. The modeling apparatus 30 includes head units 31 and 32, an ultraviolet irradiator 33, a roller 34, a carriage 35, and a stage 37. The head unit 31 independently ejects color inks and base inks (in FIG. 3, ejected droplets of color ink or base ink are labeled 1). The head unit 32 ejects droplets 2 of support ink. The ultraviolet irradiator 33 irradiates the ejected color inks, base ink, and support inks with ultraviolet light to cure them. The roller 34 smoothes the liquid films of the color inks, base ink, and support ink. The carriage 35 reciprocates each of the head units 31 and 32, etc., in the X direction in FIG. 1. The stage 37 moves a substrate 36 in the Z direction shown in FIG. 1 and in the Y direction, which is the depth direction in FIG. 1. The movement in the Y direction may be performed by the carriage 35 instead of the stage 37.

[0066] When there are multiple types of color ink corresponding to the number of colors, the head unit 31 is configured to be able to eject each color ink independently. As the nozzles in the head units 31 and 32, nozzles in known ink jet printers can be suitably used.

[0067] 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. Any of these metals coated with fluorine or silicone may also 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 modeling apparatus 30 stacks the layers while lowering the stage 37 according to the number of layers to maintain a constant gap between the roller 34 and the surface of the object. The roller 34 is preferably configured to be adjacent to the ultraviolet irradiator 33.

[0068] Furthermore, in order to prevent the ink from drying out during rest periods, the modeling device 30 may be provided with a means such as a cap for closing the nozzles in the head units 31 and 32. Furthermore, in order to prevent the nozzles from clogging during long periods of continuous use, the modeling device 30 may be provided with a maintenance mechanism for maintaining the heads.

[0069] Next, the steps performed by the modeling apparatus will be described.

[0070] The engine of the modeling device 30, while moving the carriage 35 or the stage 37, ejects droplets of colored ink from the head unit 31 based on two-dimensional data representing the cross section on the bottom side of the input two-dimensional data, and further ejects droplets of support ink from the head unit 32 in the same scan as the ejection of the colored ink droplets. Thereafter, the engine of the modeling device 30 ejects droplets of base ink from the head unit 31 in the scan after the ejection of the colored ink droplets and the ejection of the support ink droplets. As a result, droplets of colored ink and base ink are arranged at positions corresponding to pixels representing a model portion in the two-dimensional data representing the cross section on the bottom side, and droplets of support ink are arranged at positions corresponding to pixels representing a support portion, and a liquid film is formed in which droplets in adjacent positions come into contact with each other.

[0071] It is preferable to install heaters in the head units 31 and 32. Furthermore, it is preferable to install preheaters in the paths that independently supply the color inks and base inks to the head unit 31, and in the path that supplies the support ink to the head unit 32.

[0072] The smoothing process involves scraping off excess components of the colored ink, base ink, and support ink ejected onto the stage 37 using a roller 34, an example of a smoothing device, to smooth the surface and form a layer. The smoothing process may be performed once for each layer of colored ink, base ink, and support ink deposited in the Z-axis direction, or once for every 2 to 50 layers. During the smoothing process, the roller 34 may be stationary or may rotate at a positive or negative relative speed relative to the direction of travel of the stage 37. The rotational speed of the roller 34 may be constant, or may be a constant acceleration or deceleration. The rotation speed of the roller 34, as the absolute value of the speed relative to the stage 37, is preferably 50 mm / s or more and 400 mm / s or less. If the relative speed is too low, smoothing will be insufficient, resulting in a loss of smoothness. If the relative speed is too high, the device will need to be large, and vibrations and other factors may easily cause the ejected droplets to misalign, resulting in a loss of smoothness. In the smoothing step, the rotation direction of the roller 34 is preferably opposite to the direction in which the head units 31 and 32 move.

[0073] In the curing process, the engine of the modeling apparatus 30 irradiates the ultraviolet irradiator 33 with ultraviolet rays corresponding to the wavelengths of the photopolymerization initiators contained in the color inks, base ink, and support ink while moving the ultraviolet irradiator 33 using the carriage 35. In this way, the modeling apparatus 30 hardens the liquid film to form a layer.

[0074] After the bottommost layer is formed, the engine of the modeling apparatus 30 lowers the stage by one layer. The engine of the modeling device 30 ejects droplets of colored ink from the head unit 31 based on two-dimensional image data representing the second cross section from the bottom side while moving the carriage 35 or the stage 37, and then ejects droplets of support ink from the head unit 32 in the same scan as the ejection of the colored ink droplets. The engine of the modeling device 30 then ejects droplets of base ink from the head unit 31 in the scan after the ejection of the colored ink droplets and the ejection of the support ink droplets. As a result, a liquid film having a cross-sectional shape represented by the second two-dimensional data from the bottom side is formed on the bottommost layer. Furthermore, the engine of the modeling device 30 moves the ultraviolet irradiator 33 using the carriage 35, and irradiates the liquid film with ultraviolet light to harden the liquid film, thereby forming the second layer from the bottom side on the bottommost layer. The engine of the modeling device 30 uses the input 2D data in order, starting from the data closest to the bottom, and repeats the process of forming and curing a liquid film in the same manner as described above, stacking multiple layers. The number of repetitions varies depending on the amount of input 2D image data or the height and shape of the 3D model. When modeling using all the 2D image data is complete, a model part supported by the support part is obtained.

[0075] The object formed by the modeling device 30 has a model portion and a support portion. The support portion is removed from the object after modeling. Removal methods include physical removal and chemical removal. Physical removal involves applying mechanical force to remove the support portion. On the other hand, chemical removal involves immersing the object in a solvent to disintegrate and remove the support portion. There are no particular limitations on the method for removing the support portion, but chemical removal is more preferable because physical removal may damage the object. Furthermore, from the perspective of cost, removal by immersion in water is more preferable. When the removal method by immersion in water is used, a cured support ink that is water-disintegratable is selected.

[0076] 3. Three-dimensional sculpture The mechanical properties of the three-dimensional object formed by the modeling method of the present invention are not particularly limited, but preferably have the following strength, stretchability, heat resistance, or impact resistance. Examples of methods for forming a three-dimensional object having the following strength, stretchability, heat resistance, or impact resistance include a method using a base ink containing the above-mentioned hard solid component. As for the preferable mechanical properties of the three-dimensional object, the maximum tensile stress is preferably 10 MPa or more, and more preferably 30 MPa or more, in terms of strength. As for the stretchability, the tensile elongation at break is preferably 3% or more, and more preferably 8% or more. Regarding heat resistance, it is preferable that the deflection temperature under load (HDT) is 50°C or higher. As for impact resistance, the Izod impact strength is preferably 20 J / m or more, and more preferably 40 J / m or more. [Example]

[0077] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0078] <Preparation of base ink> 65 parts by weight of isobornyl acrylate (Osaka Organic Chemical Industry Co., Ltd.), 24 parts by weight of bifunctional acrylate (trade name: A-600, Shin-Nakamura Chemical Co., Ltd.), and 11 parts by weight of urethane acrylate oligomer (trade name: Shikou UV-6630B, Nippon Synthetic Chemical Industry Co., Ltd.) were uniformly mixed. Next, 4 parts by weight of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (trade name: Omunirad TPO, BASF) was added as a photopolymerization initiator and mixed uniformly. Next, 10 parts by weight of a hard solid component (Admafine K180SM-C5, Admatec Co., Ltd.) was added and mixed uniformly. Next, the mixture was passed through a filter (trade name: CCP-FX-C1B, Advantec Co., Ltd., average pore size: 3 μm) to obtain a base ink.

[0079] <Preparation of Colored Ink> 65 parts by weight of isobornyl acrylate (Osaka Organic Chemical Industry Co., Ltd.), 24 parts by weight of bifunctional acrylate (trade name: A-600, Shin-Nakamura Chemical Co., Ltd.), and 11 parts by weight of urethane acrylate oligomer (trade name: Shikou UV-6630B, Nippon Synthetic Chemical Industry Co., Ltd.) were uniformly mixed. Next, 4 parts by weight of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (trade name: Omunirad TPO, BASF) was added as a photopolymerization initiator and mixed uniformly. Next, carbon black (trade name: MHI Black #220, Mikuni Pigment Co., Ltd.) was added to the ink at a content of 1.0% by weight based on the total ink weight and mixed uniformly. The mixture was then passed through a filter (trade name: CCP-FX-C1B, Advantec, average pore size: 3 μm) to obtain a colored ink.

[0080] <Preparation of support ink> 30 parts by weight of acryloylmorpholine (manufactured by KJ Chemicals Co., Ltd.), 20 parts by weight of 1,5-pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), polypropylene glycol 2 (trade name: Actocol D-1000, manufactured by Mitsui Chemicals SKC Polyurethanes Inc., number average molecular weight: 1,000), and 2 parts by weight of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF) were added and mixed by stirring to obtain a support ink.

[0081] <Creating colored 3D objects> Example 1 In the three-dimensional object modeling apparatus shown in Figure 3, the resulting base ink, color ink, and support ink were filled into three tanks connected to an inkjet head (product name: MH2820, manufactured by Ricoh Industry Co., Ltd.). The shape of the model to be modeled was then set to 10 mm in length in the X direction, 10 mm in length in the Y direction, and 2 mm in height in the Z direction. The colored region within the model was set to a height of 1-1.2 mm in the Z direction (thickness: 0.2 mm), resembling a two-dimensional code formed by thin lines when observed in the XY plane. A support region was then set around the model. The base ink, color ink, and support ink were then ejected from the inkjet head under specified conditions (1 / 4 interlace, scanning speed: 150 mm / s, ejection frequency: 3500 kHz, 600 × 600 dpi), and the surface was then smoothed using a roller. Specifically, in the production of a layer with a colored region, the color ink and support ink were ejected in the first scan, and the base ink was ejected in the next scan. At this time, the base ink was ejected so that landing area B overlapped landing area C within the layer. The amount of ejected colored ink droplet C was 20 pL, and the amount of ejected base ink droplet B was 45 pL. Furthermore, the shape of landing area C was approximately circular with a diameter of 0.10 mm, and the shape of landing area B was approximately circular with a diameter of 0.20 mm (landing area C was smaller than landing area B). Next, a UV irradiation device (device name: SPOT CURE SP5-250DB, manufactured by Ushio Inc.) was used to irradiate the area at 350 mJ / cm. 2 The base ink, color ink, and support ink were cured by irradiating them with an amount of light of 10 ... The resulting object was then placed in 1 L of water at 40°C and subjected to ultrasonic vibration for 1 hour to remove the support portion, leaving the model portion. The model portion was then removed from the water and dried at room temperature (25°C) for 24 hours to obtain a three-dimensional object with a 2D code (see Figure 4). In addition, a three-dimensional object with a solid image was obtained in the same manner as above, except that the colored area within the model part was changed and set to a shape that would form a 5 mm x 5 mm solid image when observed in the XY plane, in a range of 1 to 1.2 mm in height in the Z direction (thickness 0.2 mm).

[0082] Example 2 A three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image were obtained in the same manner as in Example 1, except that the base ink was ejected so that landing area B did not overlap landing area C within the layer.

[0083] Example 3 A three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image were obtained in the same manner as in Example 1, except that the droplet volume C of the ejected colored ink was changed to 30 pL. When the amount of droplet C of the ejected colored ink was changed to 30 pL, the shape of the landing area C was approximately circular with a diameter of 0.13 mm (landing area C was smaller than landing area B).

[0084] Example 4 A three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image were obtained in the same manner as in Example 2, except that the droplet volume C of the ejected colored ink was changed to 30 pL. When the amount of droplet C of the ejected colored ink was changed to 30 pL, the shape of the landing area C was approximately circular with a diameter of 0.13 mm (landing area C was smaller than landing area B).

[0085] (Comparative Example 1) In Example 1, an attempt was made to form a three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image in the same manner as in Example 1, except that the amount of droplet C of the ejected colored ink was changed to 45 pL. However, the amount of ink in the colored region was excessive, and the roller performing the smoothing process collided with the cured ink in the colored region, making it impossible to form the objects. As a result of changing the amount C of the ejected colored ink droplet to 45 pL, the shape of the landing area C was approximately circular with a diameter of 0.20 mm (landing area C was the same size as landing area B).

[0086] (Comparative Example 2) In Comparative Example 1, a three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image were obtained in the same manner as in Comparative Example 1, except that the base ink was ejected so that landing area B did not overlap landing area C within the layer.

[0087] (Comparative Example 3) A three-dimensional object having a two-dimensional code (see FIG. 5) and a three-dimensional object having a solid image were obtained in the same manner as in Example 1, except that the amount of droplet B of the ejected base ink was changed to 25 pL and the amount of droplet C of the ejected colored ink was changed to 25 pL. When the amount of base ink droplet B was changed to 25 pL, the shape of landing area B was approximately circular with a diameter of 0.12 mm. When the amount of colored ink droplet C was changed to 25 pL, the shape of landing area C was approximately circular with a diameter of 0.12 mm (landing area C was the same size as landing area B).

[0088] Comparative Example 4 In Comparative Example 3, a three-dimensional object having a two-dimensional code and a three-dimensional object having a solid image were obtained in the same manner as in Comparative Example 3, except that the base ink was ejected so that landing area B did not overlap landing area C within the layer.

[0089] Next, the obtained three-dimensional object having the two-dimensional code was evaluated for printing accuracy of the colored region, modeling accuracy of the three-dimensional object, and strength according to the following methods. The results are shown in Table 1 below. The resulting three-dimensional objects having solid images were evaluated for their molding accuracy and strength according to the following methods. The results are shown in Table 1 below.

[0090] [Evaluation of printing accuracy in colored areas] The colored area of ​​the three-dimensional object having the two-dimensional code was visually observed for the presence or absence and degree of bleeding, and furthermore, a two-dimensional code reader was used to test whether the code could be read, and the results were evaluated based on the following evaluation criteria. (Evaluation criteria) A: There is no bleeding and the code can be read by a 2D code reader. B: There is some blurring and the 2D code cannot be read by a 2D code reader. C: The 2D code is so blurred that it cannot be read by a 2D code reader.

[0091] [Evaluation of the molding accuracy of 3D objects] The three-dimensional object having the two-dimensional code and the three-dimensional object having the solid image were visually observed and evaluated based on the following evaluation criteria. (Evaluation criteria) A: No concave or other distortions are observed on the top surface of the three-dimensional object. B: A depression is observed in the area above the colored area on the top surface of the three-dimensional object.

[0092] [Evaluation of the strength of three-dimensional objects] The strength of the 3D object with a 2D code and a solid image was calculated as a percentage of the strength of a 3D object made with only the base ink, and the percentage was evaluated based on the following criteria. The strength of the 3D object was measured by conducting a tensile test on the sample using a precision universal testing machine (Autograph AG-X, Shimadzu Corporation) at a tensile speed of 5 mm / min and a distance between tensile jigs of 50 mm, and the maximum stress value from the start of the test until the sample broke was taken as the measured value. (Evaluation criteria) A: The above strength ratio is 90% or more. B: The above strength ratio is 70% or more but less than 90% C: The above percentage of strength is less than 70%

[0093] [Table 1] [Explanation of symbols]

[0094] 1 Droplets of colored ink or base ink 2 Support ink droplets 10 Model Section 20 Support Department 30 Modeling equipment 31 Head Unit 32 Head Unit 33 Ultraviolet irradiation machine 34 Roller 35 Carriage 36 PCB 37 Stages [Prior art documents] [Patent documents]

[0095] [Patent Document 1] Patent No. 6389061

Claims

1. an ejection step C of ejecting an active energy ray-curable color ink by an inkjet method; a curing step C in which the ejected color ink is cured by irradiating it with active energy rays; an ejection step B of ejecting an active energy ray-curable base ink by an inkjet method; a curing step B of curing the discharged base ink by irradiating it with active energy rays, a method for forming a three-dimensional object having a colored region formed by stacking a plurality of layers by repeating a series of steps of performing the discharging step C, the curing step C, the discharging step B, and the curing step B in this order a plurality of times, A molding method characterized in that within the layer of the colored region, there is an area where an impact area C formed by the impact of the ejected colored ink and an impact area B formed by the impact of the base ink ejected onto the entire surface of the impact area C overlap, and the impact area C is smaller than the impact area B.

2. The modeling method according to claim 1 , wherein a droplet volume C of the ejected color ink is smaller than a droplet volume B of the ejected base ink.

3. 2. The modeling method according to claim 1, wherein a droplet volume C of the ejected color ink is 70% by volume or less of a droplet volume B of the ejected base ink.

4. 2. The modeling method according to claim 1, wherein a droplet volume C of the ejected color ink is 50% by volume or less of a droplet volume B of the ejected base ink.

5. The modeling method according to claim 1 , wherein the base ink contains a hard solid component having a volume average particle diameter of 10 nm or more and 1000 nm or less.

6. Furthermore, a discharge step S of discharging an active energy ray-curable support ink by an inkjet method; a curing step S in which the ejected support ink is irradiated with active energy rays to cure the ink, The discharge step C and the discharge step S are performed in the same scan, The modeling method according to claim 1 , wherein the discharging step B is performed in a scan subsequent to a scan in which the discharging step C and the discharging step S are performed.

7. the color ink contains a pigment having a volume average particle diameter of 10 nm or more and 1000 nm or less, The modeling method according to claim 1 , wherein the content of the pigment is 0.1% by mass or more with respect to the mass of the color ink.

8. the colored ink is substantially free of hard solid components; The modeling method according to claim 1 , wherein the base ink contains a hard solid component.

9. The color ink contains a pigment, The modeling method according to claim 1 , wherein the base ink does not substantially contain a pigment.

10. an ejection step C of ejecting an active energy ray-curable color ink by an inkjet method; a curing step C in which the ejected color ink is cured by irradiating it with active energy rays; an ejection step B of ejecting an active energy ray-curable base ink by an inkjet method; a curing step B in which the discharged base ink is cured by irradiating it with active energy rays; a smoothing step of smoothing the ink layer formed by the ejection; Including, a method for forming a three-dimensional object having a colored region formed by stacking a plurality of layers by repeating a series of steps of performing the discharging step C, the curing step C, the discharging step B, and the curing step B in this order a plurality of times, The smoothing step is provided between the discharging step B and the curing step B, Within the layer of the colored region, there is a region where an impact region C formed by the impact of the ejected colored ink and an impact region B formed by the impact of the base ink ejected on the entire surface of the impact region C overlap, A molding method, wherein the landing area C is smaller than the landing area B.

11. a discharge means C for discharging active energy ray-curable color ink by an inkjet method; a curing means C for curing the ejected color ink by irradiating it with active energy rays; an ejection means B for ejecting an active energy ray-curable base ink by an inkjet method; a curing means B for curing the discharged base ink by irradiating it with active energy rays, a modeling apparatus that forms a three-dimensional object having a colored region formed by stacking a plurality of layers by repeating discharging by the discharging means C, curing by the curing means C, discharging by the discharging means B, and curing by the curing means B in this order a plurality of times, Within the layer of the colored region, there is provided an area where an impact region C formed by the impact of the ejected colored ink and an impact region B formed by the impact of the base ink ejected on the entire surface of the impact region C overlap each other, The molding apparatus is characterized in that the landing area C is smaller than the landing area B.

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