Manufacturing method for three-dimensional objects

Abstract

To provide a novel method for eliminating or reducing discoloration of a three-dimensional molded object molded using an electron beam curing ink.SOLUTION: A manufacturing method for three-dimensional molded object includes: a preparation step S1 for preparing a processed three-dimensional molded object that is three-dimensional molded using electron beam curing ink; and an aging step S2 to reduce a coloration of discolored portions of the processed three-dimensional molded object by performing irradiation treatment S2-1 irradiating the processed three-dimensional molded object with light containing a wavelength of less than 430 nm and heat treatment S2-2 applying heat to it.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] 2. Description of the Related Art A known method for forming a three-dimensional object is a method for forming a three-dimensional object using electron beam curable ink such as UV curable ink.

[0003] For example, a liquid electron beam curable ink is ejected using an inkjet or dispenser to form an ink layer, and then the ink is cured by irradiating it with an electron beam to form a cured ink layer.This ejection and curing process is repeated to stack the ink cured layers and create a three-dimensional shape.

[0004] Some three-dimensional objects use transparent ink (clear ink) and colored ink as electron beam curable ink. In this case, the three-dimensional object is composed of transparent portions in the clear ink area and colored portions in the colored ink area. In such three-dimensional objects composed of transparent portions, the transparent portions may turn yellow or the colored portions may discolor after production.

[0005] Methods for eliminating discoloration such as yellowing of such three-dimensional objects have been investigated.

[0006] For example, Patent Document 1 describes a method for irradiating a three-dimensional object with light containing light having a wavelength in the range of 430 to 500 nm and not containing light having a wavelength of 400 nm or less, such that the total irradiation intensity of the light having a wavelength of 430 to 500 nm on the surface of the three-dimensional object is 15 W / m 2 The treatment method for irradiating the material as described above is described. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5393239 Summary of the Invention [Problem to be solved by the invention]

[0008] When creating a three-dimensional object, depending on the design, the outside of the object may be covered with a transparent ink (clear ink). In such three-dimensional objects, the area of ​​the clear ink becomes larger and thicker, which can cause the clear ink to discolor or become more noticeable. Furthermore, when using an ink composition specifically designed for UV-LEDs, the polymerization initiator can cause the ink to turn yellow.

[0009] However, even if the object is treated after completion of molding using the method described in Patent Document 1, there are problems in that it is difficult to completely remove discoloration and it takes a long time.

[0010] Therefore, an object of the present invention is to provide a novel method for eliminating or reducing discoloration of a three-dimensionally shaped object formed using an electron beam curable ink. [Means for solving the problem]

[0011] The present inventors conducted studies in light of the above-mentioned problems and analyzed three-dimensionally molded objects formed using electron beam curable inks, and found that discoloration is caused by residual polymerization initiators, intermediate products, etc., that irradiation with a specified light reduces discoloration because these residual polymerization initiators and intermediate products disappear, and that further heating reduces discoloration. Based on this finding, the present inventors conducted further studies and completed the present invention.

[0012] That is, in order to solve the above-mentioned problems, a manufacturing method of a three-dimensional structure according to a first aspect of the present invention is a manufacturing method of a three-dimensional structure, comprising: a preparation step of preparing a three-dimensional object to be processed that is three-dimensionally modeled using the electron beam curable ink; an aging process in which the three-dimensional object is irradiated with light having a wavelength of less than 430 nm and heat-treated to reduce the color of discolored portions of the three-dimensional object; Includes.

[0013] The method for producing a three-dimensionally shaped object having the above-described configuration is a novel method for eliminating or reducing discoloration of a three-dimensionally shaped object that is three-dimensionally shaped using an electron beam curable ink.

[0014] In the aging step, the irradiation treatment and the heat treatment are preferably carried out simultaneously.

[0015] According to the manufacturing method configured as above, the color of the yellowed portion decreases rapidly.

[0016] The electron beam curable ink preferably contains, as a photopolymerization initiator, at least one selected from the group consisting of a phosphine oxide-based photopolymerization initiator, an alkylphenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, and a titanocene-based photopolymerization initiator.

[0017] The manufacturing method configured as above is highly effective in reducing the color of yellowed areas discolored by residual photopolymerization initiator or incompletely reacted photopolymerization initiator.

[0018] The heat treatment is preferably carried out by applying heat at a temperature of 10°C or higher and 100°C or lower.

[0019] According to the manufacturing method configured as above, the color of the yellowed portion decreases rapidly. [Effects of the Invention]

[0020] According to the present invention, a novel method is provided for eliminating or reducing discoloration of a three-dimensionally shaped object formed using an electron beam curable ink. [Brief explanation of the drawings]

[0021] [Figure 1]1 is a flowchart of a method for manufacturing a three-dimensional object according to an embodiment of the present invention. [Figure 2] 1 is a schematic view showing a three-dimensional object to be processed according to an embodiment of the present invention. [Figure 3] Graph showing the aging effect. [Figure 4] Spectral spectrum of the light source (indoor ceiling fluorescent lamp) in Experimental Example 1. [Figure 5] Illuminance and spectral spectrum of the light source (45W three-wavelength fluorescent lamp) in Experimental Example 2. [Figure 6] Illuminance and spectral spectrum of the light source (single wavelength lamp (385 nm)) in Experimental Example 5. [Figure 7] Illuminance and spectral spectrum of the light source (single wavelength lamp (405 nm)) in Experimental Example 6. [Figure 8] Illuminance and spectral spectrum of the light source (incandescent bulb (UVA+UVB)) in Experimental Example 9. [Figure 9] Illuminance and spectral spectrum of the light source in Experimental Example 10 (incandescent bulb, 3-wavelength type (Hyper Sun UV100W)). [Figure 10] Illuminance and spectral spectrum of the light source (LED lamp (100W incandescent bulb, daylight color)) in Experimental Example 11. [Figure 11] Graph showing the aging effect of Comparative Examples 2 to 5. [Figure 12] Graph showing the aging effect of Comparative Examples 6 to 9. [Figure 13] Graph showing the aging effect of Comparative Examples 10 to 12. [Figure 14] Graph showing the aging effect of Examples 1 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, a method for manufacturing a three-dimensional object according to one embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[0023] This manufacturing method includes a preparation step S1 and an aging step, as shown in Figure 1. Each step will be described in detail below.

[0024] (Preparation process S1) In the preparation step S1, a three-dimensionally shaped object 1 to be processed is prepared by three-dimensionally shaping using an electron beam curable ink (see FIG. 1). FIG. 2 is a schematic diagram showing the three-dimensionally shaped object 1 to be processed, which includes, for example, a colorless transparent portion 2 and a colored opaque portion 3.

[0025] The electron beam curable ink according to this embodiment contains, for example, an electron beam curable compound, a photopolymerization initiator, a sensitizer, a coloring material, and other components.

[0026] Examples of electron beam curable compounds include radical polymerizable compounds. The radical polymerizable compound is not particularly limited as long as it is a compound having radical polymerizability, but acrylates are preferred in terms of polymerizability, durability of the cured product, solubility of initiators and sensitizers, etc.

[0027] Examples of the acrylate include monofunctional acrylates such as phenol EO-modified acrylate, nonylphenol EO-modified acrylate, and ethoxydiethylene glycol acrylate; bifunctional acrylates such as hexanediol diacrylate, hexanediol EO-modified diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, neopentyl glycol PO-modified diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, bisphenol A EO-modified diacrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate; and polyfunctional acrylates such as trimethylolpropane triacrylate, trimethylolpropane EO-modified triacrylate, trimethylolpropane PO-modified triacrylate, glycerin propoxy triacrylate, pentaerythritol triacrylate, pentaerythritol EO-modified tetraacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexaacrylate.

[0028] These radical polymerizable compounds may be used either individually or in combination.

[0029] The photopolymerization initiator generates radicals upon irradiation with light, curing the electron beam-curable compound. A photopolymerization initiator that is particularly effective when curing is performed by light emitted from an LED is preferred. Examples of photopolymerization initiators include aminoalkylphenone-based photopolymerization initiators, phosphine oxide-based photopolymerization initiators, alkylphenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and titanocene-based photopolymerization initiators. Furthermore, as cationic photopolymerization initiators, iodonium salt-based photopolymerization initiators and sulfonium salt-based photopolymerization initiators can be used. These photopolymerization initiators may be contained in the ink alone, or two or more types may be mixed and contained in the ink.

[0030] Examples of the aminoalkylphenone photopolymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one.

[0031] Examples of the phosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0032] Examples of alkylphenone-based photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, etc. Examples of thioxanthone-based photopolymerization initiators include 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, etc.

[0033] Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0034] Examples of titanocene photopolymerization initiators include bis(cyclopentadienyl)-di-chloro-titanium, bis(cyclopentadienyl)-di-phenyl-titanium, bis(cyclopentadienyl)-bis(2,3,4,5,6-pentafluorophenyl)titanium, bis(cyclopentadienyl)-bis(2,6-difluorophenyl)titanium, and bis(η5-cyclopentadienyl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium.

[0035] Examples of cationic photopolymerization initiators include iodonium salt-based photopolymerization initiators such as iodonium (4-methylphenyl) [4-(2-methylpropyl) phenyl] hexafluorophosphate, and examples of sulfonium salt-based photopolymerization initiators include bis [4-(diphenylsulfonio) phenyl] sulfide bis hexafluorophosphate.

[0036] The sensitizer imparts photosensitivity to a wavelength region in which the photopolymerization initiator has no photosensitivity, or increases the photosensitivity of the photopolymerization initiator. Examples of the sensitizer include thioxanthone-based sensitizers.

[0037] Examples of thioxanthone sensitizers include thioxanthone, 2,4-diethyl-9H-thioxanthen-9-one, and 2-isopropylthioxanthone.

[0038] Examples of coloring materials include known dyes and pigments, and examples of pigments include inorganic pigments and organic pigments. In the three-dimensional object 1 to be processed in Fig. 1, the colorless transparent portion 2 is a region of electron beam curable ink that does not contain a coloring material or that contains a blue coloring material to a degree that does not impair transparency in order to reduce the yellowish color, and the colored opaque portion 3 is a region of electron beam curable ink that contains a coloring material such as an inorganic pigment or an organic pigment.

[0039] Examples of inorganic pigments include titanium oxide, zinc oxide, zinc oxide, tripon, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, red iron oxide, molybdenum red, chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, Prussian blue, cobalt blue, cerulean blue, manganese violet, cobalt violet, and mica.

[0040] Examples of organic pigments include azo pigments, azomethine pigments, polyazo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, indigo pigments, thioindigo pigments, quinophthalone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, and carbon black.

[0041] Other components include fillers, colorants, dispersants, plasticizers, surfactants, surface conditioners, leveling agents, antifoaming agents, antioxidants, charge imparting agents, bactericides, preservatives, deodorizers, charge control agents, wetting agents, antiskinning agents, fragrances, pigment derivatives, and solvents.

[0042] (3D modeling) Three-dimensional modeling using electron beam curable ink involves ejecting the electron beam curable ink using an inkjet system, dispenser system, or the like to form an ink layer, irradiating the ink layer with light having a wavelength of, for example, 405 nm to 420 nm to cure the ink layer and form a cured layer, and performing this ink ejection and curing process multiple times to obtain a three-dimensional object formed of multiple layers. Typically, the ink ejection step and the curing step are performed alternately, but the curing step can also be performed after multiple ink ejection steps.

[0043] In the preparation step S1, three-dimensional modeling is performed as described above, and the obtained three-dimensional model can be prepared as the three-dimensional model 1 to be processed, or a three-dimensional model obtained separately can also be prepared as the three-dimensional model 1 to be processed.

[0044] (Aging process S2) The aging process S2 involves performing an irradiation process S2-1 in which the three-dimensional object is irradiated with light having a wavelength of less than 430 nm, and a heat treatment S2-2 in which heat is applied to the object, thereby reducing the color of the discolored parts of the three-dimensional object.

[0045] The irradiation treatment S2-1 and the heat treatment S2-2 may be performed simultaneously, or the heat treatment S2-2 may be performed after the irradiation treatment S2-1, or the heat treatment S2-2 may be performed after the irradiation treatment S2-1.

[0046] (Irradiation treatment S2-1) In the irradiation process S2-1, the processed 3D object is irradiated with light having a wavelength of less than 430 nm to remove photopolymerization initiator residues or unreacted photopolymerization initiator intermediates that may remain in the non-processed 3D object after the modeling is completed and discolor the object. The wavelength of less than 430 nm contained in the light irradiated to the non-processed 3D object is within the wavelength range for removing only the photopolymerization initiator residues without affecting the resin and other components that make up the non-processed 3D object. The photopolymerization initiator used in electron beam 3D modeling is expected to be decomposed by the electron beam during modeling. However, in reality, the photopolymerization initiator contained in the ink is not completely consumed, and the reaction caused by the photopolymerization initiator remaining in the non-processed 3D object progresses, resulting in discoloration of the non-processed 3D object. Therefore, the purpose of the irradiation process S2-1 is to remove the photopolymerization initiator.

[0047] In the irradiation process S2-1, a light source that generates light containing wavelengths of less than 430 nm is placed at an arbitrary distance from the three-dimensional object to be processed, and the light is irradiated.

[0048] The light source that generates light containing wavelengths of less than 430 nm is not particularly limited as long as it is a light source that emits light with wavelengths of less than 430 nm, but examples include short-wavelength lamps and three-wavelength fluorescent lamps that emit light with wavelengths of less than 430 nm.

[0049] The illuminance of the light is not particularly limited as long as it is within the range in which aging occurs, but it is recommended that the illuminance be 20 W / m on the surface of the three-dimensional object to be treated. 2 It is preferable that it is 50W / m or more. 2 More preferably, it is 60W / m or more. 2 The illuminance of the light can also be adjusted by the distance between the light source and the three-dimensional object to be processed.

[0050] The reduction in color of the discolored portion of the three-dimensional object by the irradiation treatment S2-1 proceeds at a slower rate than by the heat treatment S2-2, but the amount of reduction in color is greater than by the heat treatment S2-2. irradiationProcessing S2- 1 The time is, for example, preferably 1 hour or more, more preferably 2 hours or more, and particularly preferably 6 hours or more. irradiation Processing S2- 1 Even if the treatment time is extended, the effect of reducing the color of the discolored part decreases, so from the viewpoint of treatment time, 24 hours or less is preferable.

[0051] (Heat treatment S2-2) In the heat treatment S2-2, heat is applied to the three-dimensional object to be treated.

[0052] The means for applying heat is not particularly limited, but may include heating with a heater, immersion in a thermostatic bath, etc. When this is performed simultaneously with the irradiation treatment S2-1, a light source may also be used as a heat source.

[0053] The heat treatment S2-2 can be performed by placing the three-dimensional object to be treated under temperature conditions of, for example, 10° C. or higher but below the temperature at which the three-dimensional object to be treated deteriorates due to heat. The temperature conditions are, for example, preferably 10° C. or higher, more preferably 20° C. or higher, particularly preferably 30° C. or higher, and preferably 100° C. or lower, more preferably 80° C. or lower, and particularly preferably 70° C. or lower. If the temperature of the heat treatment S2-2 exceeds 100° C., thermal deformation or discoloration may occur.

[0054] The heat treatment S2-2 reduces the color of the discolored portion of the three-dimensional object at a faster rate than the irradiation treatment S2-1, but the amount of color reduction is smaller than that of the irradiation treatment S2-1. The heat treatment S2-2 time is preferably, for example, 1 hour or more, more preferably 2 hours or more, and particularly preferably 6 hours or more. Furthermore, since the rate of color reduction in the discolored portion of the three-dimensional object gradually decreases, a longer heat treatment S2-2 time may result in thermal deformation or discoloration. Therefore, in terms of treatment time, a treatment time of 24 hours or less is preferred. Furthermore, it is preferable to adjust the time appropriately depending on the temperature of the heat treatment S2-2.

[0055] (Example) EXAMPLES The present invention will be described below based on examples, but is not limited to these examples. The characteristics of the light source and the effect of aging were evaluated by the following methods.

[0056] (illuminance) A light source was placed at a predetermined distance from the evaluation sample to irradiate it with light, and the illuminance was measured on the surface of the evaluation sample using a spectroradiometer (manufactured by Konica Minolta, Inc., product name: CL-500A).

[0057] (Spectral spectrum (spectral waveform)) A light source was placed at a predetermined distance from the evaluation sample to irradiate it with light, and the spectral irradiance was measured on the surface of the evaluation sample using a spectral irradiance meter (manufactured by Konica Minolta, Inc., product name: CL-500A).

[0058] (Color of evaluation sample) The chromaticity was measured under the following conditions using a spectrophotometer (manufactured by Konica Minolta, Inc., product name: CM-2600d). SN:D1012947 Light source: D65 Field of view: 10° Reflection / Transmission: Reflection Specular reflection processing: SCI+SCE (values ​​are managed by SCE) Measurement diameter: SAV (3mm)

[0059] (Aging rating: saturation c * ) Lightness L * , chromaticity a * b * Measure the saturation c * The rate at which discoloration was reduced and the final amount of reduction were evaluated. Sample size: 30 x 30 x 20 mm Measurement device: Spectrophotometer (Konica Minolta, Inc., product name: CM-2600d) c * When the condition is less than 10, aging is good.

[0060] (Aging evaluation: integrating sphere holder) The degree of aging completion can be confirmed by: 1) UV-vis: disappearance of peaks specific to photopolymerization initiators, 2) colorimetry: especially b * This was confirmed by the trend. Sample size: 30 x 30 x 20 mm Measurement device: UV-vis (integrating sphere holder) (manufactured by JASCO Corporation, product name: ISV-722) Analysis: Color is calculated using built-in UV-vis analysis software Furthermore, measurements using an integrating sphere are not affected by the background at the time of measurement, and it is possible to measure the color of the object itself.

[0061] (Manufacturing Example 1: Creation of an evaluation sample) A UV-curable ink (manufactured by Mimaki Engineering Co., Ltd., product name: MH-110PCL, ingredients: acrylic monomer, oligomer, TPO, ACMO, etc.) was used as the electron beam curable ink, and a transparent three-dimensional shape measuring 40 x 40 x 2 mm was printed using an inkjet 3D printer (manufactured by Mimaki Engineering Co., Ltd., product name: 3DUJ-553) to create the three-dimensional object E to be processed.

[0062] (Experimental Example 1) The spectral irradiance of an indoor fluorescent lamp (three-wavelength type) on the ceiling was measured as a light source. The spectral spectrum is shown in Figure 4. The processed 3D model E was aged for 22 hours by irradiating it with light at room temperature using a straight tube fluorescent lamp attached to the ceiling indoors as the light source. At this time, the distance from the fluorescent lamp on the ceiling indoors as the light source to the processed 3D model E was 1.9 m. The brightness L at the initial time, 1, 3, 6, and 22 hours later * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were both 2.4 W / m 2 The results are shown in Figure 3. Here, "initial" refers to the time when aging began after light irradiation began (0 hours).

[0063] (Experimental Example 2) The illuminance and spectral irradiance of a 45W bulb-type three-wavelength fluorescent lamp (ALBA ALB-45F) used as a light source were measured at a distance of 20cm. The illuminance was 69.6W / m 2 The illuminance and spectral spectrum are shown in Figure 5 (here, bulb-type refers to fluorescent lamps with a spherical, spiral, D-shaped, or other shaped fluorescent tube). The three-dimensional object E to be treated was aged for 22 hours by irradiating it with light from a distance of 5 cm using a bulb-type 45W three-wavelength fluorescent lamp (ALBA ALB-45F (with ultraviolet cut film (Yamahira Co., Ltd., WINCOS (formerly Lumicool) 1905UH, blocking ultraviolet rays from 300 nm to 500 nm))) as a light source. The surface temperature of the sample was heated by the lamp to 60°C. The brightness L at the initial time, 1, 3, 6, and 22 hours later was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 76.7 and 50.3 W / m, respectively. 2 The results are shown in Figure 3.

[0064] (Experimental Example 3) The processed three-dimensional object E was aged for 22 hours by irradiating it with light from a bulb-type 45W three-wavelength fluorescent lamp (ALBA ALB-45F (without UV cut film)) at a distance of 18 cm. The surface temperature of the sample was heated by the lamp to 35°C. The brightness L at the initial time, 1, 3, 6 and 22 hours later was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 80.7 and 48.1 W / m, respectively. 2 The results are shown in Figure 3.

[0065] (Experimental Example 4) The illuminance and spectral irradiance of a single-wavelength lamp (385 nm) used as a light source were measured at a distance of 20 cm. The illuminance was 93.0 lux. The illuminance and spectral spectrum are shown in Figure 6. The three-dimensional object E was aged for 22 hours by irradiating it with light from a single wavelength lamp (385 nm) at a distance of 22 cm. The surface temperature of the sample was heated by the lamp to 28°C. The brightness L at the initial stage, 1, 3, 6, and 22 hours after irradiation was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 76.2 and 67.2 W / m, respectively. 2 The results are shown in Figure 3.

[0066] (Experimental Example 5) The illuminance and spectral irradiance of a single-wavelength lamp (405 nm) (INTEGRATION 405) used as a light source were measured at a distance of 20 cm. The illuminance was 81.31 lux. The illuminance and spectral spectrum are shown in Figure 7. The processed three-dimensional object E was aged for 22 hours by irradiating it with light from a single wavelength lamp (405 nm) (INTEGRATION 405) at a distance of 20 cm. The surface temperature of the sample was heated by the lamp to 26°C. The brightness L at the initial stage, 1, 3, 6, and 22 hours later was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 82.3 and 85.6 W / m, respectively. 2 The results are shown in Figure 3.

[0067] (Experimental Example 6) The evaluation sample after aging for 22 hours in Experimental Example 5 was aged for 1 hour in a thermostatic chamber at 70° C. The results are shown in FIG.

[0068] (Experimental Example 7) The processed three-dimensional object E was aged for 22 hours by irradiating it with light from a single-wavelength lamp (405 nm) (INTEGRATION405) at a distance of 20 cm with the heater set to 50°C (heater surface temperature 40°C, sample surface temperature 38°C). The results are shown in Figure 3.

[0069] (Experimental Example 8) The illuminance and spectral irradiance of an incandescent lamp (UVA + UVB) as a light source were measured at a distance of 20 cm. The illuminance was 122.5 lux. The illuminance and spectral spectrum are shown in Figure 8. The three-dimensional object E to be treated was aged for 22 hours by irradiating it with light from an incandescent lamp (UVA + UVB) at a distance of 24 cm. The surface temperature of the sample was heated by the lamp to 57°C. The brightness L at the initial stage, 1, 3, 6 and 22 hours later was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 79.7 and 76.1 W / m, respectively. 2 The results are shown in Figure 3.

[0070] (Experimental Example 9) The illuminance and spectral irradiance of a three-wavelength incandescent bulb (Hyper Sun UV 100W) used as the light source were measured at a distance of 20 cm. The illuminance was 58.0 lux. The illuminance and spectral spectrum are shown in Figure 9. The processed three-dimensional object E was aged for 22 hours by irradiating it with light from a three-wavelength incandescent bulb (Hyper Sun UV 100W) at a distance of 12 cm. The surface temperature of the sample was heated by the lamp to 90°C. The brightness L at the initial stage, 1, 3, 6, and 22 hours later was * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 56.1 and 75.4 W / m, respectively. 2 The results are shown in Figure 3.

[0071] (Experimental Example 10) The illuminance and spectral irradiance of an LED lamp (incandescent bulb, 100W, daylight color) used as a light source were measured at a distance of 20 cm. The illuminance was 83.0 lux. The illuminance and spectral spectrum are shown in Figure 10. The processed three-dimensional object E was aged for 22 hours by irradiating it with light from a distance of 20 cm using an LED lamp (incandescent bulb 100W daylight white) as the light source. The sample surface temperature was heated by the lamp to 30°C. The brightness L at the initial stage, 1, 3, 6, and 22 hours later was* , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 75.0 and 71.3 W / m, respectively. 2 The results are shown in Figure 3.

[0072] (Experimental Example 11) The three-dimensional object E was immersed in a thermostatic chamber at 70°C for 22 hours without using a light source. The initial brightness L, 1, 3, 6, and 22 hours later * , chromaticity a * b * Measure the saturation c * The initial and 22-hour illuminances were 75.0 and 71.3 W / m, respectively. 2 The results are shown in Figure 3.

[0073] (Summary of Experimental Examples 1 to 11) In Experimental Examples 1 to 11, a colorimeter was used to measure * The measurement was performed using the color of the background on which the sample is placed. * Aging is favorable under conditions where the ratio is less than 10. Specifically, compared to leaving the product under fluorescent lights on an indoor ceiling (Experimental Example 1), irradiating the product with any light or applying only heat can achieve a certain degree of aging effect, but discoloration removal is insufficient or slow. In contrast, when irradiation treatment using light with wavelengths less than 430 nm and heat treatment using heat were performed, as in Experimental Examples 3, 6, and 7, the aging effect was rapid and discoloration removal was also excellent.

[0074] (Comparative Example 1) The treated three-dimensional object E was stored in a dark place for 40 hours, and the change in color was examined. The brightness L after the initial, 8, 16, 40, and 64 hours * , chromaticity a * b * is measured with an integrating sphere holder, and the saturation c * The results are shown in Table 1.

[0075] [Table 1]

[0076] (Comparative Examples 2 to 5) The three-dimensional object E was aged for 40 hours by heating (40°C, 50°C, 60°C, or 70°C, respectively) without using a light source. The initial brightness L, after 1, 8, 16, and 40 hours * , chromaticity a * b * is measured with an integrating sphere holder, and the saturation c * The results are shown in Table 2 and Figure 11.

[0077] [Table 2]

[0078] (Comparative Examples 6 to 9) The three-dimensional object E to be processed was illuminated with a 405 nm single wavelength lamp (INTEGRATION405) as a light source, adjusting the distance to achieve an illuminance of 30 mW / cm. 2 , 15mW / cm 2 , 5mW / cm 2 , or 1 mW / cm 2 The aging was carried out for 40 hours by irradiating light at 1000 kJ / s. The initial brightness, 8, 16 and 40 hours later, * , chromaticity a * b * is measured with an integrating sphere holder, and the saturation c * The results are shown in Table 3 and Figure 12.

[0079] [Table 3]

[0080] (Comparative Examples 10 to 12) A 385 nm single wavelength lamp was used as the light source for the three-dimensional object E to be processed, and the distance was adjusted to achieve an illuminance of 30 mW / cm. 2 , 15mW / cm 2 , or 5 mW / cm 2 The aging was carried out for 40 hours by irradiating light at 1000 kJ / s. The initial brightness, 8, 16 and 40 hours later,* , chromaticity a * b * is measured with an integrating sphere holder, and the saturation c * The results are shown in Table 4 and Figure 13.

[0081] [Table 4]

[0082] Example 1 , Comparative Examples 13 to 15 ) The three-dimensional object E to be processed was illuminated with a 405 nm single wavelength lamp (INTEGRATION405) as a light source, adjusting the distance to achieve an illuminance of 30 mW / cm. 2 , 15mW / cm 2 , 5mW / cm 2 , or 1 mW / cm 2 The aging was carried out for 40 hours while irradiating light at 70°C. The initial brightness L * , chromaticity a * b * is measured with an integrating sphere holder, and the saturation c * The results are shown in Table 5 and Figure 14.

[0083] [Table 5]

[0084] (Comparative Examples 1 to 12, Example 1 , Comparative Examples 13 to 15 Summary of In Comparative Example 1, the product was stored in a dark place, and it can be seen that almost no aging effect was obtained. In Comparative Examples 2 to 5, in which only heat treatment was performed, when heat treatment was performed at high temperature, the aging effect could be observed to some extent after 8 hours, but it can be seen that the removal of discoloration was insufficient. In Comparative Examples 6 to 9 and Comparative Examples 10 to 12, in which only irradiation treatment was performed by irradiating with light containing wavelengths of less than 430 nm, the aging effect could be observed to some extent at high illuminance, but the aging rate was slow, and the rate was slower at an illuminance of 15 mW / cm. 2 and an additional 30mW / cm 2It can be seen that there is almost no effect even if the temperature is increased to 430 nm. , Comparative Examples 13 to 15 After 8 hours, a significant aging effect was already observed.

[0085] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention. [Explanation of symbols]

[0086] 1 3D object to be processed 2 Colorless transparent part 3 Colored opaque area S1 Preparation process S2 Aging process S2-1 Heat treatment S2-2 Irradiation treatment

Claims

1. A method for manufacturing a three-dimensional object, comprising: a preparation step of preparing a three-dimensional object to be processed that is three-dimensionally modeled using the electron beam curable ink; an aging process in which the three-dimensional object is irradiated with light having a wavelength of less than 430 nm and heat-treated to reduce the color of discolored portions of the three-dimensional object; Including, In the irradiation treatment, the illuminance of the light applied is 20 W / m 2 or more on the surface of the three-dimensional object to be treated, and the irradiation treatment time is 1 hour or more and 24 hours or less.

2. The method for manufacturing a three-dimensional object according to claim 1 , wherein the irradiation treatment and the heat treatment are carried out simultaneously in the aging step.

3. 3. The method for producing a three-dimensional object according to claim 1 or 2, wherein the electron beam curable ink contains, as a photopolymerization initiator, at least one selected from the group consisting of a phosphine oxide-based photopolymerization initiator, an alkylphenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, and a titanocene-based photopolymerization initiator.

4. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the heat treatment is performed by applying heat of 10°C or higher and 100°C or lower.

5. The method for manufacturing a three-dimensional object described in claim 1, wherein the conditions of the aging process are such that the saturation c* calculated by measuring the color of the processed three-dimensional object with a spectrophotometer after the aging process is less than 10.

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