JP2025019446A - Three-dimensional object manufacturing device and method for manufacturing three-dimensional object - Google Patents

Abstract

[Problem] The present disclosure aims to provide a three-dimensional object manufacturing device and a three-dimensional object manufacturing method that can reduce the size of the entire device and keep costs down. [Solution] The three-dimensional object manufacturing device 100 according to the present disclosure includes a primer ink ejection head 101 that ejects primer ink, a first irradiation device 121, an ejection head unit 110 including a first color ink ejection head 111 that ejects a first color ink, and a second color ink ejection head 112 that ejects a second color ink, a second irradiation device 122, and a transport device 105 (105a, 105b, 105c) that transports the three-dimensional object 1 in this order. [Selected Figure] Figure 4

Description

This disclosure relates to a manufacturing apparatus for a three-dimensional object and a manufacturing method for a three-dimensional object.

There is a growing trend to conserve resources, and there is a demand to reduce single-use plastics. Labels on containers such as PET bottles are discarded after their intended use is completed, and plastic labels in particular are difficult to recycle, so the disposal rate is very high. In order to achieve a label-less society, a technology has been proposed for printing directly on containers (see, for example, Patent Document 1). Patent Document 1 discloses a device that prints directly on the sides of containers, and discloses a print head that operates according to the drop-on-demand principle.

A printing device that prints ultraviolet-curable inks, including cyan ink (C), magenta ink (M), black ink (K), and yellow ink (Y), has also been disclosed (see, for example, Patent Document 2). Patent Document 2 describes a printing device technology that uses a letterpress printing method, but in the printing device shown in Figure 1 of Patent Document 2, the printing units for each ink and the ultraviolet ray irradiation units that cure each ink are arranged alternately around the transport drum.

U.S. Pat. No. 1,123,592 International Publication No. WO 2010/150780

Patent Document 1 discloses a device with only one printer head. However, in order to meet the demand for high aesthetics when printing directly on containers, a printing device with multiple printer heads compatible with multiple color inks is required. In general, when printing multiple color inks, ultraviolet light is irradiated after each color printing, as in the printing device disclosed in Patent Document 2, in order to suppress bleeding between the color inks and obtain a highly detailed design. However, when printing directly on the side of a container as in Patent Document 1, if ultraviolet light is irradiated for all colors of color ink as in the device of Patent Document 2, a total of eight or more devices must be arranged, including four or more inkjet heads (C, M, Y, K) and four or more UV lamps per printing surface, and a certain distance must be secured between the inkjet heads and the UV lamps to prevent stray light from the UV lamps. This leads to problems such as the complexity of the printing device, the large size of the printing device, and the increase in cost.

The present disclosure aims to provide a three-dimensional object manufacturing device and a three-dimensional object manufacturing method that can reduce the overall size of the device and keep costs down.

The three-dimensional object manufacturing device according to the present invention is a three-dimensional object manufacturing device that forms a printed part having a primer layer and an ink layer provided on the primer layer on the outer surface of a three-dimensional object, the primer layer includes a cured product of a primer ink that is an active energy ray curable inkjet ink, the ink layer includes a coloring part that includes a cured product of a coloring ink that is an active energy ray curable inkjet ink containing a coloring material, the coloring ink includes at least a first coloring ink and a second coloring ink that is a different color from the first coloring ink, and the three-dimensional object manufacturing device is characterized in that it includes a primer ink ejection head that ejects the primer ink, a first irradiation device, an ejection head unit including a first coloring ink ejection head that ejects the first coloring ink and a second coloring ink ejection head that ejects the second coloring ink, a second irradiation device, and a transport device that transports the three-dimensional object in this order.

The three-dimensional object manufacturing device according to the present invention includes a configuration further including a third irradiation device disposed downstream of the conveying device relative to the second irradiation device.

In the three-dimensional object manufacturing apparatus according to the present invention, the ink layer further has a background printing section between the primer layer and the coloring section, and the background printing section includes a cured product of background white ink, which is an active energy ray curable inkjet ink containing a white coloring material, and the three-dimensional object manufacturing apparatus further has a background printing section forming unit between the first irradiation device and the ejection head unit, and the background printing section forming unit preferably has, in order, a background white ink ejection head that ejects the background white ink, and a fourth irradiation device. By curing the background white ink prior to the ink of the coloring section, the color ink can be fixed more stably on the background printing section. As a result, a clearer image can be obtained.

In the three-dimensional object manufacturing apparatus according to the present invention, it is preferable that the transport distance of the transport device between the primer ink ejection head and the first irradiation device is longer than the transport distance of the transport device between the ejection head unit and the second irradiation device. This makes it possible to obtain a clearer image by suppressing bleeding of color inks while making the primer layer obtained by leveling the primer ink flat.

The method for manufacturing a three-dimensional object according to the present invention is a method for manufacturing a three-dimensional object, which forms a printed part having a primer layer and an ink layer provided on the primer layer on the outer surface of the three-dimensional object, the primer layer includes a cured product of a primer ink, which is an active energy ray curable inkjet ink, the ink layer includes a color part, the color part includes a cured product of a color ink, which is an active energy ray curable inkjet ink containing a coloring material, the color ink includes at least a first color ink and a second color ink of a different color from the first color ink, and the method for manufacturing a three-dimensional object is characterized by having a color ink applying process including at least a first color ink applying process of applying the first color ink onto the cured product of the primer ink and a second color ink applying process of applying the second color ink onto the cured product of the primer ink, and a second irradiation process of irradiating the color ink group including the first color ink and the second color ink applied onto the cured product of the primer ink in the color ink applying process with active energy rays.

The method for manufacturing a three-dimensional object according to the present invention includes a form further including a primer ink application step of applying the primer ink to the outer surface of the three-dimensional object prior to the color ink application step, and a first irradiation step of irradiating the primer ink applied to the outer surface of the three-dimensional object with active energy rays.

The method for producing a three-dimensional object according to the present invention includes a form further including a third irradiation step of further irradiating the color ink group with active energy rays after the second irradiation step.

In the method for manufacturing a three-dimensional object according to the present invention, the ink layer further has a background printed portion between the primer layer and the cured product of the color ink, and the background printed portion includes a cured product of a background white ink, which is an active energy ray curable inkjet ink containing a white coloring material, and the method for manufacturing a three-dimensional object further has a background printed portion forming step between the first irradiation step and the color ink applying step, and the background printed portion forming step preferably has a background white ink applying step of applying the background white ink onto the primer layer, and a fourth irradiation step of irradiating the background white ink applied onto the primer layer with active energy rays. By curing the background white ink prior to the ink of the color portion, the color ink can be fixed more stably on the background printed portion. As a result, a clearer image can be obtained.

In the method for manufacturing a three-dimensional object according to the present invention, it is preferable that the time from the end of the primer ink application step to the start of irradiation of the active energy rays in the first irradiation step is longer than the time from the end of the color ink application step to the start of irradiation of the active energy rays in the second irradiation step. This makes it possible to obtain a clearer image by suppressing bleeding of the color ink while making the primer layer obtained by leveling the primer ink flat.

The present disclosure provides a three-dimensional object manufacturing device and a three-dimensional object manufacturing method that can reduce the overall size of the device and keep costs down.

1 is an image showing an example of a three-dimensional object. FIG. 2 is a schematic cross-sectional view showing an example of a printing unit. FIG. 4 is a schematic cross-sectional view showing another example of a printing unit. 1 is a schematic configuration diagram showing an example of a three-dimensional object manufacturing apparatus according to an embodiment of the present invention; FIG. 4 is a schematic configuration diagram showing another example of the three-dimensional object manufacturing apparatus according to the present embodiment.

The embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to these descriptions. Various modifications of the embodiment may be made as long as the effects of the present invention are achieved.

The three-dimensional object manufacturing apparatus according to this embodiment is an apparatus that forms a printing section 20 having a primer layer 21 and an ink layer 22 provided on the primer layer 21, as shown in FIG. 2 or FIG. 3, on the outer surface of a three-dimensional object 1, as shown in FIG. 1, for example.

(Three-dimensional object)
FIG. 1 is an image showing an example of a three-dimensional object. In FIG. 1, the three-dimensional object 1 is shown as a plastic container having a container body 10 having a mouth portion 11 and a body portion 12 connected to the mouth portion 11 as an example, but the present invention is not limited to this. The material of the three-dimensional object 1 is not particularly limited, and is, for example, plastic, glass, quartz, or metal. The three-dimensional object 1 may be a beverage container. The beverage container is, for example, a plastic container, a metal can, or a glass bottle as shown in FIG. 1. Of these, it is preferable that the three-dimensional object 1 is a plastic container.

As an example of the material of the three-dimensional object 1, the type of plastic is not particularly limited, but examples include polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin (PP), cycloolefin copolymer resin (COC, cyclic olefin copolymer), ionomer resin, poly-4-methylpentene-1 resin, polymethyl methacrylate resin, polystyrene resin, ethylene-vinyl alcohol copolymer resin, acrylonitrile resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyamide resin, polyamideimide resin, polyacetal resin, polycarbonate resin, polysulfone resin, or tetrafluoroethylene resin, acrylonitrile-styrene resin, and acrylonitrile-butadiene-styrene resin. Among these, PET is particularly preferred. When the three-dimensional object 1 is a plastic container, the capacity of the plastic container is not particularly limited, and is, for example, 100 ml to 3000 ml.

The method for molding the plastic container is not particularly limited, but may be, for example, a blow molding method. Specifically, first, a preform is produced by injection molding a thermoplastic resin, and then the preform is blow molded to produce a plastic container having a shape in which a mouth portion 11 and a body portion 12 are connected in sequence, as shown in FIG. 1.

The container body 10 has an internal space for accommodating the contents. The contents are not particularly limited, but may be, for example, liquids such as beverages, alcoholic beverages, and seasonings, foods, medicines, or industrial products. The beverages may be, for example, white beverages such as milk, yogurt drinks, lactic acid bacteria drinks, dairy drinks, and alcoholic drinks, colored and transparent beverages such as straight tea, lemon tea, green tea, fruit juice drinks, carbonated drinks, and beer, cloudy beverages such as milk tea and coffee, or clear beverages such as sports drinks, water, carbonated water, and chuhai.

The mouth 11 is a filling port and a pouring spout for the contents. A cap (not shown) is attached to the mouth 11 to seal the bottle. A neck support ring may be formed at the lower end of the mouth 11.

The body 12 is a portion connected to the lower end of the mouth 11, and may have, in order from the mouth 11 side, an upper body 12a whose diameter increases from the lower end of the mouth 11 downward, a cylindrical body main body 12b, and a lower body 12c that is connected to the body main body 12b with approximately the same diameter and has a grounding surface. The upper body 12a is sometimes called a shoulder due to its shape. The body main body 12b is, for example, cylindrical or regular n-sided cylindrical (where n is an integer of 4 or more). The lower body 12c becomes the bottom of the container body 10.

The printed section 20 is provided on at least a part of the upper body 12a, the body main body 12b, and the lower body 12c. In FIG. 1, an example is shown in which an identification code section showing a one-dimensional code is provided as the printed section 20 on the body main body 12b, but the present invention is not limited to this. If the body 12 has ribs, it is preferable to provide the identification code section in a portion that avoids the ribs. The printed section 20 may include a character string (not shown) or a design image section (not shown) in addition to the identification code section. The character string includes product information such as the product name, raw material name, content amount, expiration date, and manufacturer. The design image section includes, for example, a logo showing the product name or company name, or an image to enhance the design, such as a color, a painting, a photograph, an illustration, or a pattern.

The printed portion 20 may be provided in only one area or in two or more areas. The printed portion 20 is preferably provided in a light-transmitting portion of the body 12. Examples of light-transmitting forms include achromatic and colorless transparent bottles with a visible light transmittance that allows the viewer to see through the body 12, chromatic and colored transparent bottles with a visible light transmittance that allows the viewer to see through the body 12, semi-transparent bottles with a visible light transmittance that allows the viewer to read the text on the other side of the body 12 by the light that has passed through the body 12, and opaque bottles with a visible light transmittance that allows the viewer to see the text on the other side of the body 12 by the light that has passed through the body 12. Examples of containers with at least a portion of the body 12 that is light-transmitting include, but are not limited to, a general PET bottle with the entire body 12 being colorless and transparent, and a foamed PET bottle with at least a portion of the body 12 being semi-transparent or opaque with a visible light transmittance.

Figure 2 is a schematic cross-sectional view showing an example of a printed part. As shown in Figure 2, the printed part 20 has, in order from the outer surface side of the body part 12, a primer layer 21 and an ink layer 22.

The primer layer 21 is a layer for ensuring adhesion between the outer surface of the three-dimensional object 1 and the ink of the printing part 20. The primer layer 21 may or may not have alkali releasability. In this embodiment, it is preferable that the primer layer 21 has alkali releasability. For example, in a recycling system, containers such as PET bottles are crushed and pulverized, and then sorted into crushed containers with a high specific gravity and crushed lids with a low specific gravity by a specific gravity separation method. This sorting is performed, for example, by immersing the container in a processing liquid (e.g., an alkaline aqueous solution). The primer layer 21 has alkali releasability, so that the container can be made to have excellent recyclability. In this specification, alkali releasability refers to the property that the primer layer 21 peels off from the body part 12 when immersed in an alkaline solution. The alkali releasability may be, for example, that the primer layer 21 dissolves in an alkali and peels off from the body part 12, or that the primer layer 21 does not dissolve in an alkali and peels off at the interface between the body part 12 and the primer layer 21 in the alkaline solution. In this embodiment, the primer layer 21 is preferably such that, for example, when a region of the three-dimensional object 1 including at least the printed portion 20 is immersed and stirred in a 1.5% by mass aqueous sodium hydroxide solution at 85°C to 90°C for 15 minutes, at least a portion of the printed portion 20 peels off from the outer surface of the three-dimensional object 1. The thickness of the primer layer is not particularly limited, but is preferably 6 to 26 μm, and more preferably 11 to 15 μm.

The primer layer 21 is a coating film of a primer ink, which is an active energy ray-curable inkjet ink, and contains a primer cured product, which is a cured product of the primer ink. The primer layer 21 may consist of only the primer cured product, or may contain additives such as fillers or colorants such as pigments and dyes in addition to the primer cured product.

The active energy ray curable inkjet ink preferably contains, for example, a polymerizable monomer and a polymerizable surfactant. From the viewpoint of alkali peelability, the polymerizable monomer preferably contains at least a polyfunctional monomer. The polyfunctional monomer is not particularly limited as long as it is a monomer having two or more polymerizable groups. From the viewpoint of curability, the polyfunctional monomer is preferably a polyfunctional radical polymerizable monomer, and more preferably a polyfunctional ethylenically unsaturated monomer, for example, 3-methyl-1,5-pentanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, and 1,10-decanediol di(meth)acrylate. The polymerizable monomer may further contain a monofunctional monomer in addition to the polyfunctional monomer. The monofunctional monomer is not particularly limited as long as it is a monomer having one polymerizable group. From the viewpoint of curability, the monofunctional monomer is preferably a monofunctional radical polymerizable monomer, and more preferably a monofunctional ethylenically unsaturated monomer. Examples of the monofunctional ethylenically unsaturated monomer include monofunctional (meth)acrylates, monofunctional (meth)acrylamides, monofunctional aromatic vinyl compounds, monofunctional vinyl ethers, and monofunctional N-vinyl compounds, such as cyclic trimethylolpropane formal (meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, stearyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the polymerizable surfactant include polymerizable silicone surfactants, polymerizable fluorine surfactants, and polymerizable acrylic surfactants. Commercially available polymerizable silicone surfactants include, for example, BYK-UV3500, 3505, 3530, 3570, 3575, and 3576 (manufactured by BYK Corporation), Tegorad 2100, 2200, 2250, 2300, 2500, 2600, 2700, 2800, 2010, and 2011 (manufactured by Evonik Corporation), EBECRYL 350 and 1360 (manufactured by Daicel-Allnex Corporation), and KP-410, 411, 412, 413, 414, 415, 416, 418, 420, 422, and 423 (manufactured by Shin-Etsu Silicones Co., Ltd.). Examples of polymerizable fluorine-based surfactants include compounds having a perfluoroalkyl group and a polymerizable group. Commercially available polymerizable fluorosurfactants include, for example, MEGAFAC RS-56, RS-72-K, RS-75, RS-76-E, RS-65-NS, RS-78, and RS-90 (manufactured by DIC Corporation), which are fluorosurfactants having a (meth)acryloyl group. Examples of polymerizable acrylic surfactants include compounds having a polymerizable group bonded to a side chain of a poly(meth)acrylic structure. Examples of commercially available polymerizable acrylic surfactants include CN821 (manufactured by Sartomer Corporation). The active energy ray-curable inkjet ink may contain at least one type of polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator that generates radicals, such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide or 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-[1-methylethylene)]}oxymethyl)propane.

The primer ink may be a clear ink that does not contain a coloring material, or a colored ink that contains a coloring material. The color of the coloring material may be any color, such as black, white, blue, red, green, yellow, or orange, and is not particularly limited.

The ink layer 22 is formed on the primer layer 21 and is a layer showing letters, numbers, or symbols (hereinafter, letters, numbers, or symbols may be collectively referred to as letters, etc.), and/or design images such as illustrations or icons. The ink layer 22 may consist of only one layer, or may consist of two or more layers.

The colored portion 22A constitutes the characters and/or design images in the ink layer 22. For example, in FIG. 1, the colored portion 22A is a collection of bars and a group of numbers of a one-dimensional code printed in black. The colored portion 22A is a coating film of colored ink, which is an active energy ray curable inkjet ink containing a coloring material, and includes an ink cured product that is a cured product of the colored ink. The colored ink has the same basic structure as the active energy ray curable inkjet ink exemplified as the primer ink, and includes a coloring material. The coloring material is also called a colorant, and examples of the coloring material include dyes and pigments. From the viewpoint of durability such as heat resistance, light resistance, and water resistance, it is preferable that the coloring material is a pigment. As the pigment, either organic pigments or inorganic pigments that are usually commercially available can be used. As the pigment, for example, the pigments described in "Dictionary of Pigments" edited by Ito Seijiro (published in 2000), W. Herbst, K. Examples of the pigments include those described in Hunger "Industrial Organic Pigments", JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A. The color of the coloring material may be any color, such as black, white, blue, red, green, yellow, orange, etc., and is not particularly limited. The colored portion 22A may or may not have alkaline peelability. In this embodiment, when the primer layer 21 has alkaline peelability, it is more preferable that the colored portion 22A does not have alkaline peelability. The colored portion 22A may consist of only the ink cured product, or may contain additives such as fillers or colorants such as pigments and dyes in addition to the ink cured product.

In this embodiment, the color ink has at least a first color ink having a first color as the color material, and a second color ink having a second color as the color material, which is a different color from the first color ink. The colors of the first color ink and the second color ink may be different from each other, and the colors are not particularly limited. For example, the first color ink is preferably any one selected from the group consisting of black ink, cyan ink, yellow ink, and magenta ink. The second color ink is preferably any one selected from the group consisting of black ink, cyan ink, yellow ink, and magenta ink and different from the first color ink. In addition to the first color ink and the second color ink, the color ink further has a third color ink and a fourth color ink, and the first color ink, the second color ink, the third color ink, and the fourth color ink are preferably yellow ink, magenta ink, cyan ink, and black ink, respectively. The printing unit 20 can be full-color printed, and a three-dimensional object with excellent cosmetic properties can be obtained. In this embodiment, the colors and number of colors of the color inks are not limited to the examples described above. The color inks may further include a color white ink.

Figure 3 is a schematic cross-sectional view showing another example of the printed portion. In this embodiment, the ink layer 22 may further have a background printed portion 22B between the primer layer 21 and the colored portion 22A, as shown in Figure 3. The background printed portion 22B is, for example, a rectangular white solid print in the printed portion 20 in Figure 1. The background printed portion 22B contains a cured product of a background white ink, which is an active energy ray curable inkjet ink containing a white coloring material. The background white ink has the same basic composition as the active energy ray curable inkjet ink exemplified as the primer ink, and contains a white coloring material. The white coloring material may be a white coloring material from the coloring materials exemplified as the coloring ink, and is not particularly limited, but is, for example, titanium dioxide. The background printed portion 22B is preferably a solid print provided between the primer layer 21 and the information image portion 22A, and may be a single coat or two or more coats. The thickness of the background printed part 22B is not particularly limited, but is preferably 6 to 26 μm, and more preferably 11 to 15 μm. The background printed part 22B may or may not have alkaline releasability. In this embodiment, when the primer layer 21 has alkaline releasability, it is more preferable that the background printed part 22B does not have alkaline releasability. The background printed part 22B may consist of only the cured product of the background white ink, or may contain additives such as fillers or colorants such as pigments and dyes in addition to the cured product of the background white ink.

(3D object manufacturing equipment)
4 is a schematic diagram showing an example of a three-dimensional object manufacturing apparatus according to the present embodiment. The three-dimensional object manufacturing apparatus 100 includes a primer ink ejection head 101 for ejecting primer ink, a first irradiation device 121, an ejection head unit 110 including a first color ink ejection head 111 for ejecting a first color ink, and a second color ink ejection head 112 for ejecting a second color ink, a second irradiation device 122, and a transport device 105 (105a, 105b, 105c) for transporting the three-dimensional object 1 in this order.

The ejection head 101 for the primer ink is not particularly limited as long as it is an inkjet head used in an inkjet recording method. The inkjet recording method is not particularly limited as long as it is a method capable of recording an image, and known methods such as a continuous type or an on-demand type can be used. In this embodiment, it is preferable that the inkjet recording method is an on-demand type. The on-demand type includes a piezo type and a thermal type, and in this embodiment, it is more preferable that it is a piezo type.

The first irradiation device 121 is a device that irradiates active energy rays to cure active energy ray-curable inkjet ink, and cures the primer ink attached to the outer surface of the three-dimensional object 1. Examples of active energy rays include gamma rays, beta rays, electron beams, ultraviolet rays, and visible light. Of these, it is preferable that the active energy rays are ultraviolet rays. The peak wavelength of the ultraviolet rays is not particularly limited, but is preferably 200 to 410 nm, and more preferably 250 to 400 nm. The light source for irradiating ultraviolet rays is not particularly limited, and is, for example, a lamp such as a mercury lamp or a metal halide lamp, a light-emitting diode such as an ultraviolet light-emitting diode (UV-LED), or a laser light source such as a gas laser, a solid-state laser, or an ultraviolet laser diode (UV-LD).

The first irradiation device 121 may be a provisional curing device for provisionally curing the primer ink, or a formal curing device for formally curing the primer ink. In this specification, "provisional curing" refers to polymerizing only a portion of the polymerizable monomer in the active energy ray-curable inkjet ink, and the irradiation of active energy rays for provisional curing is sometimes referred to as "pinning exposure." In addition, in this specification, "formal curing" refers to polymerizing substantially all of the polymerizable monomer in the active energy ray-curable inkjet ink, and the irradiation of active energy rays for formal curing is sometimes referred to as "formal exposure."

The ejection head unit 110 includes at least an ejection head 111 for a first color ink and an ejection head 112 for a second color ink. As shown in FIG. 4, the ejection head unit 110 preferably further includes an ejection head 113 for a third color ink and an ejection head 114 for a fourth color ink in addition to the ejection head 111 for the first color ink and the ejection head 112 for the second color ink. These ejection heads 111, 112, 113, and 114 for the color inks are preferably arranged along the transport path 106 of the transport device 105b. The ejection heads 111, 112, 113, and 114 for the color inks can be inkjet heads similar to the ejection head 101 for the primer ink. The arrangement of the color ink ejection heads 111, 112, 113, and 114 in the ejection head unit 110 is not particularly limited, but for example, it is preferable to arrange, in order from the upstream side of the transport direction C of the transport device 105b, a black head that ejects black ink as the first color ink ejection head 111, a cyan head that ejects cyan ink as the second color ink ejection head 112, a magenta head that ejects magenta ink as the third color ink ejection head 113, and a yellow head that ejects yellow ink as the fourth color ink ejection head 114. The ejection droplet volume of each color ink ejection head 111, 112, 113, and 114 is preferably 1 to 100 pL (picoliters), more preferably 3 to 80 pL, and even more preferably 3 to 50 pL.

The ejection head unit 110 may further include a color white ink ejection head (not shown) that ejects color white ink. The order of the color white ink ejection heads may be any number among the color ink ejection heads 111, 112, 113, and 114 included in the ejection head unit 110. For example, the color white ink ejection head may be disposed on the most upstream side of the transport direction C, i.e., between the first irradiation device 121 and the first color ink ejection head 111 in FIG. 4, between the first color ink ejection head 111 and the second color ink ejection head 112, between the second color ink ejection head 112 and the third color ink ejection head 113, between the third color ink ejection head 113 and the fourth color ink ejection head 114, or on the most downstream side of the transport direction C, i.e., between the fourth color ink ejection head 114 and the second irradiation device 122 in FIG. 4.

The second irradiation device 122 is a device that irradiates active energy rays to cure the active energy ray curable inkjet ink, and cures the color ink adhered to the cured primer ink. The second irradiation device 122 is a temporary curing device for temporary curing the color ink. The second irradiation device 122 may also function as both a temporary curing device and a main curing device for the color ink by subjecting the color ink to pinning exposure and then main exposure. The second irradiation device 122 may be a device similar to the first irradiation device 121.

The conveying device 105 (105a, 105b, 105c) is a device that moves the three-dimensional object 1 along the conveying path 106, and is, for example, a belt conveyor or a rotary table. In principle, the conveying device 105 (105a, 105b, 105c) preferably conveys the three-dimensional object 1 continuously at a constant speed while the manufacturing apparatus 100 is in operation, but may be temporarily stopped as necessary, the three-dimensional object 1 may be conveyed intermittently, or the conveying speed may be changed. The conveying device 105 (105a, 105b, 105c) includes a first conveying line 105a that conveys the three-dimensional object 1 before printing, a second conveying line 105b that conveys the three-dimensional object 1 to the printing area, and a third conveying line 105c that conveys the three-dimensional object 1 after printing. In FIG. 4, as an example, a rotary-type manufacturing apparatus in which the first conveyor line 105a and the third conveyor line 105c are belt conveyors and the second conveyor line 105b is a rotary table is shown, but the present invention is not limited thereto. For example, the first to third conveyor lines 105a, 105b, and 105c may all be belt conveyors, and a linear-type manufacturing apparatus may be used. In addition, the conveyor 105 may be stopped, and the ejection head unit 110 may be moved to the stopped three-dimensional object 1 to perform printing. In FIGS. 4 and 5, only one three-dimensional object 1 is shown as a representative, and the other three-dimensional objects 1 are omitted, and it is preferable that the conveyor 105 (105a, 105b, and 105c) conveys multiple three-dimensional objects 1. It is preferable that the multiple three-dimensional objects 1 are arranged on the conveyor 105 (105a, 105b, and 105c) at a predetermined interval from each other. In addition, the three-dimensional object 1 may be arranged in a single row on the conveying device 105 (105a, 105b, 105c), or in multiple rows of two or more rows. When the three-dimensional object 1 is arranged in multiple rows, each component including the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122 may be arranged in multiple rows according to the row of the three-dimensional object 1. In addition, each component including the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122 is arranged radially outward of the rotary table (conveying device 105b) with respect to the conveying path 106 of the three-dimensional object 1, but the present invention is not limited to this. They may be arranged radially inward of the rotary table (conveying device 105b) with respect to the conveying path 106 of the three-dimensional object 1, or may be arranged on both radially outward and radially inward sides of the rotary table (conveying device 105b) with respect to the conveying path 106 of the three-dimensional object 1.

The manufacturing apparatus 100 for the three-dimensional object 1 according to the present embodiment preferably further includes a rotation device (not shown) for the three-dimensional object 1. The rotation device for the three-dimensional object 1 is a device that rotates (spins) the three-dimensional object 1 around the central axis while moving the three-dimensional object 1 with the conveying device 105. The rotation device for the three-dimensional object 1 is not particularly limited, but may be, for example, a turntable installed on the conveying device 105, or a lifting and rotating device that lifts and rotates the three-dimensional object 1. When the rotation device for the three-dimensional object 1 is a turntable, the turntable rotates the three-dimensional object 1 around the central axis of the three-dimensional object 1 by rotating the turntable while moving the three-dimensional object 1 on the conveying path 106 with the conveying device 105. When the rotation device for the three-dimensional object 1 is a lifting and rotating device, the lifting and rotating device lifts the three-dimensional object 1 from the conveying surface of the conveying device 105 and rotates the lifted three-dimensional object 1 around the central axis of the three-dimensional object 1. By providing the manufacturing apparatus 100 with a rotation device, the three-dimensional object 1 can be rotated and printing can be performed on the entire circumference of the side of the three-dimensional object 1. In addition, after the primer ink is applied, the three-dimensional object 1 is rotated on the spot using a rotation device, allowing time for the primer ink to level.

The manufacturing apparatus 100 for the three-dimensional object 1 according to this embodiment preferably further includes an alignment device (not shown) for the three-dimensional object 1. The alignment device for the three-dimensional object 1 is a device that orients the three-dimensional object 1 conveyed by the conveying device 105 in a predetermined direction. Orienting the three-dimensional object 1 in a predetermined direction means, for example, facing the surface on which the printing unit 20 (for example, shown in FIG. 1) is to be formed to each component including the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122. By providing the alignment device in the manufacturing apparatus 100, printing misalignment can be suppressed. In addition, the printing unit 20 can be provided at a predetermined location. The alignment device for the three-dimensional object 1 is not particularly limited, but is, for example, a clamping tool that clamps the three-dimensional object 1 and moves it to a predetermined position on the conveying surface of the conveying device 105, and an alignment rib that is provided on the conveying surface of the conveying device 105 and guides the three-dimensional object 1 to a predetermined position on the conveying surface.

The manufacturing apparatus 100 for the three-dimensional object 1 according to this embodiment preferably further includes a holding device (not shown) for the three-dimensional object 1. The holding device for the three-dimensional object 1 is a device for holding the three-dimensional object 1 transported by the transport device 105. The holding device for the three-dimensional object 1 is not particularly limited, but may be, for example, a clamping arm for gripping the three-dimensional object 1, or a holding guide for supporting the three-dimensional object 1. By providing the manufacturing apparatus 100 with a holding device, printing misalignment can be suppressed. In addition, the printing unit 20 can be provided at a predetermined location.

"The conveying device 105 (105a, 105b, 105c) that conveys the three-dimensional object 1 in this order" means that the conveying device 105 conveys the three-dimensional object 1 so that the three-dimensional object 1 is processed in the order of at least the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122. In this embodiment, it is preferable that the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122 are arranged in this order from the upstream side along the conveying path 106. In this embodiment, other components may be arranged between the respective components of the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122.

In conventional three-dimensional object manufacturing devices, when two or more types of color inks are used, the color ink ejection heads and the color ink irradiation devices are arranged alternately to prevent the inks from bleeding, and the color inks are attached and pinned alternately. For this reason, when the number of color ink colors increases, it is necessary to install a set of ejection heads and irradiation devices corresponding to the number of colors, which causes a problem of the manufacturing device becoming larger. In the three-dimensional object manufacturing device 100 according to this embodiment, two or more types of color inks are pinned together in one irradiation device, making it possible to reduce the number of irradiation devices and reduce the size of the manufacturing device. In addition, by adopting a revolution printing method in which high-speed printing is performed using an inkjet method while moving the three-dimensional object 1 with the conveying device 105, it is possible to obtain image quality that ensures the visibility of characters such as ingredient information of products even when some pinning is eliminated.

As shown in FIG. 4, the three-dimensional object manufacturing apparatus 100 according to this embodiment also includes a configuration that further includes a third irradiation device 123 that is disposed downstream of the conveying device 105 from the second irradiation device 122.

The third irradiation device 123 is a device that irradiates active energy rays to cure the active energy ray curable inkjet ink. The third irradiation device 123 is a main curing device for main curing of the color ink. The third irradiation device 123 may be a device similar to the first irradiation device 121. The third irradiation device 123 is preferably disposed downstream of the second irradiation device 122 on the transport path 106.

Figure 5 is a schematic diagram showing another example of a three-dimensional object manufacturing apparatus according to this embodiment. In the three-dimensional object manufacturing apparatus 100 according to this embodiment, the ink layer 22 further has a background printing section 22B between the primer layer 21 and the coloring section 22A as shown in Figure 3, and the background printing section 22B includes a cured product of background white ink, which is an active energy ray curable inkjet ink containing a white colorant, and the three-dimensional object manufacturing apparatus 100 further has a background printing section forming unit 130 between the first irradiation device 121 and the ejection head unit 110 as shown in Figure 5, and the background printing section forming unit 130 preferably has a background white ink ejection head 131 for ejecting background white ink and a fourth irradiation device 132 in that order.

It is preferable that the background printing unit 130 is disposed between the first irradiation device 121 and the first color ink ejection head 111.

The background white ink ejection head 131 can be an inkjet head similar to the primer ink ejection head 101.

The fourth irradiation device 132 is a device that irradiates active energy rays to cure the active energy ray curable inkjet ink, and is a device for curing the background white ink. The fourth irradiation device 132 is preferably arranged downstream of the background white ink ejection head 131 on the transport path 106. The fourth irradiation device 132 can be a device similar to the first irradiation device 121. The fourth irradiation device 132 may be a temporary curing device for temporary curing of the background white ink, or a permanent curing device for permanent curing of the background white ink. By providing the fourth irradiation device 132 upstream of the transport path 6 of the ejection head unit 110, the background white ink can be cured prior to the ink of the colored portion, and the colored ink can be fixed more stably on the background printed portion. As a result, a clearer image can be obtained.

In the three-dimensional object manufacturing apparatus 100 according to the present embodiment, the transport distance of the three-dimensional object 1 of the transport device 105 between the primer ink ejection head 101 and the first irradiation device 121 is preferably longer than the transport distance of the three-dimensional object 1 of the transport device 105 between the ejection head unit 110 and the second irradiation device 122. The transport distance of the three-dimensional object 1 of the transport device 105 between the ejection head unit 110 and the second irradiation device 122 is the transport distance of the three-dimensional object 1 of the transport device 105 between the color ink ejection head (the fourth color ink ejection head 114 in FIG. 4) arranged at the most downstream of the transport path 106 of the ejection head unit 110 and the second irradiation device 122. Here, if the transport speed of the three-dimensional object 1 in the section between the primer ink ejection head 101 and the first irradiation device 121 is the same as the transport speed of the three-dimensional object 1 in the section between the ejection head unit 110 and the second irradiation device 122, the transport distance and the transport time are in a proportional relationship in both sections. For example, when the primer ink ejection head 101, the first irradiation device 121, the ejection head unit 110, and the second irradiation device 122 are all located along the rotary table as in the second conveying line 105b shown in FIG. 4, the conveying distance and the conveying time are in a proportional relationship in both sections. When the conveying distance and the conveying time are in a proportional relationship in both sections, the conveying distance of the three-dimensional object 1 of the conveying device 105 between the primer ink ejection head 101 and the first irradiation device 121 is made longer than the conveying distance of the three-dimensional object 1 of the conveying device 105 between the ejection head unit 110 and the second irradiation device 122, so that the conveying time in the section between the primer ink ejection head 101 and the first irradiation device 121 can be secured longer. As a result, the primer layer obtained by leveling the primer ink can be made flat, while suppressing the bleeding of the color ink, thereby obtaining a clearer image. By leveling the primer ink, the primer cured product can be made into a continuous film without pinholes through which the ink cured product can penetrate, and all of the ink cured product can be positioned on the primer cured product. As a result, there are no parts of the outer surface of the three-dimensional object 1 where the ink layer 22 is in direct contact, and alkaline peelability is ensured throughout the entire area, including the center of the printed portion 20. The transport distance of the three-dimensional object 1 by the transport device 105 between the primer ink ejection head 101 and the first irradiation device 121 is preferably 2 to 10 times, more preferably 2.5 to 8 times, and even more preferably 3 to 5 times, the transport distance of the three-dimensional object 1 by the transport device 105 between the ejection head unit 110 and the second irradiation device 122.

In the three-dimensional object manufacturing apparatus 100 according to the present embodiment, the transport distance of the three-dimensional object 1 of the transport device 105 between the primer ink ejection head 101 and the first irradiation device 121 is more preferably longer than the transport distance of the three-dimensional object 1 of the transport device 105 between the color ink ejection head (the first color ink ejection head 111 in FIG. 4) arranged at the most upstream of the transport path 106 of the ejection head unit 110 and the second irradiation device 122. The transport distance of the three-dimensional object 1 of the transport device 105 between the primer ink ejection head 101 and the first irradiation device 121 is preferably 2 to 10 times the transport distance of the three-dimensional object 1 of the transport device 105 between the color ink ejection head (the first color ink ejection head 111 in FIG. 4) arranged at the most upstream of the transport path 106 of the ejection head unit 110 and the second irradiation device 122, more preferably 2.5 to 8 times, and even more preferably 3 to 5 times. By setting the range in this way, the primer ink can be leveled while the color ink can be cured in a short time after landing, which prevents the ink dots from spreading. As a result, it is possible to draw designs with greater detail.

(Method for manufacturing three-dimensional objects)
The method for producing a three-dimensional object according to this embodiment is a method for forming a printed portion 20 having a primer layer 21 and an ink layer 22 provided on the primer layer 21 on the outer surface of a three-dimensional object 1 as shown in Fig. 2 or 3. The method for producing a three-dimensional object according to this embodiment has a color ink applying step including at least a first color ink applying step of applying a first color ink onto a cured product of the primer ink, and a second color ink applying step of applying a second color ink onto the cured product of the primer ink, and a second irradiation step of irradiating the color ink group including the first color ink and the second color ink applied onto the cured product of the primer ink in the color ink applying step with active energy rays.

The method for manufacturing a three-dimensional object according to this embodiment includes a form further including a primer ink application step of applying primer ink to the outer surface of the three-dimensional object 1 prior to the color ink application step, and a first irradiation step of irradiating the primer ink applied to the outer surface of the three-dimensional object 1 with active energy rays.

Next, each process will be described using the three-dimensional object manufacturing device 100 shown in FIG. 4 or FIG. 5 as an example, but the method for manufacturing a three-dimensional object according to this embodiment is not limited to the manufacturing device.

The three-dimensional object 1 is transferred from the transport device 105a to the transport device 105b, transported to the printing area, and moved to the ink landing range of the primer ink ejection head 101. In the primer ink application process, primer ink is ejected from the primer ink ejection head 101. This causes the primer ink to adhere to the outer surface of the three-dimensional object 1. The amount of primer ink ejected from the primer ink ejection head 101 is not particularly limited, but is preferably 1 to 100 pL (picoliters), more preferably 3 to 80 pL, and even more preferably 3 to 50 pL.

The three-dimensional object 1 with the primer ink attached thereto is transported in the transport direction C and moves into the irradiation range of the active energy rays from the first irradiation device 121. In the first irradiation step, active energy rays are irradiated from the first irradiation device 121. In the first irradiation step, the active energy rays from the first irradiation device 121 may be pinning exposure or main exposure. Of these, it is more preferable that in the first irradiation step, the active energy rays from the first irradiation device 121 are pinning exposure.

The three-dimensional object 1 then moves to the ink landing range of the first color ink ejection head 111. The color ink application process includes at least a first color ink application process and a second color ink application process. In addition to the first color ink application process and the second color ink application process, the color ink application process may further include a third color ink application process of applying a third color ink onto the cured product of the primer ink, and a fourth color ink application process of applying a fourth color ink onto the cured product of the primer ink.

In the first color ink application process, the first color ink is ejected from the first color ink ejection head 111. This causes the first color ink to adhere to the cured primer of the three-dimensional object 1. The first color ink is, for example, black ink.

The three-dimensional object 1 with the first color ink attached thereto is transported in the transport direction C and moves to the ink landing range of the second color ink ejection head 112. In the second color ink attachment process, the second color ink is ejected from the second color ink ejection head 112. This causes the second color ink to adhere to the cured primer of the three-dimensional object 1. The second color ink is, for example, a cyan ink.

The three-dimensional object 1 with the second color ink attached thereto is transported in the transport direction C, and moves sequentially to the ink landing range of the third color ink ejection head 113 and the ink landing range of the fourth color ink ejection head 114, and the third color ink and the fourth color ink are attached to the cured primer of the three-dimensional object 1 in the same manner as in the first color ink attachment process and the second color ink attachment process. The third color ink is, for example, a magenta ink, and the fourth color ink is, for example, a yellow ink. The droplet volume of each color ink ejected from each color ink ejection head 111, 112, 113, and 114 is not particularly limited, but is preferably 1 to 100 pL (picoliters), more preferably 3 to 80 pL, and even more preferably 3 to 50 pL.

The color ink application step may further include a color white ink application step of applying a color white ink onto the cured product of the primer ink. The timing of the color white ink application step may be, for example, after the first irradiation step and before the first color ink application step, i.e., at the very beginning of the color ink application step, between the first color ink application step and the second color ink application step, between the second color ink application step and the third color ink application step, between the third color ink application step and the third color ink application step, or just before the second irradiation step, i.e., at the very end of the color ink application step. In the present invention, the timing of the color white ink application step is not particularly limited.

The three-dimensional object 1 with the color inks attached thereto is transported in the transport direction C and moves into the irradiation range of the active energy rays from the second irradiation device 122. In the second irradiation step, active energy rays are irradiated from the second irradiation device 122. The second irradiation step is a step of collectively curing the color ink group including at least the first color ink and the second color ink. In the second irradiation step, it is preferable that the active energy rays from the second irradiation device 122 are pinning exposure. Furthermore, the second irradiation step may be a step of further curing the primer provisionally cured in the first irradiation step in addition to provisionally curing the color ink group.

In the three-dimensional object manufacturing apparatus 100 according to this embodiment, the printing speed in the color ink application process is preferably 80 to 600 bpm (bottles per minute), and more preferably 100 to 300 bpm. Here, bpm (bottles per minute) is an index indicating the number of three-dimensional objects 1 that can be printed per minute. For example, in the manufacturing apparatus 100 shown in FIG. 5, the above-mentioned printing speed can be achieved by adjusting the rotation speed of the rotary table, which is the second conveying line 105b.

In conventional manufacturing methods for three-dimensional objects, when two or more types of color inks are used, the application process and the irradiation process are performed alternately for each color ink to prevent the inks from bleeding into each other. For this reason, as the number of color ink colors increases, an irradiation process corresponding to the number of colors must be performed, resulting in an increase in the number of manufacturing processes. In the manufacturing method for three-dimensional objects according to this embodiment, two or more types of color inks are pinned together in one irradiation process to eliminate partial pinning, thereby simplifying the manufacturing method. In addition, by adopting a revolution printing method in which high-speed printing is performed using an inkjet method while moving the three-dimensional object 1, it is possible to obtain image quality that ensures the visibility of text such as ingredient information for products, even when partial pinning is eliminated.

The method for producing a three-dimensional object according to this embodiment includes a form further including a third irradiation step of further irradiating the color ink group with active energy rays after the second irradiation step. After the second irradiation step, the three-dimensional object 1 is transported in the transport direction C and moves to the irradiation range of the active energy rays of the third irradiation device 123. In the third irradiation step, active energy rays are irradiated from the third irradiation device 123. In the third irradiation step, it is preferable that the active energy rays from the third irradiation device 123 are the main exposure.

In the method for producing a three-dimensional object according to this embodiment, the ink layer 22 further includes a background printed portion 22B between the primer layer 21 and the cured product of the color ink, as shown in FIG. 3, and the background printed portion 22B includes a cured product of background white ink, which is an active energy ray curable inkjet ink containing a white colorant. The method for producing a three-dimensional object further includes a background printed portion forming step between the first irradiation step and the color ink application step, and the background printed portion forming step preferably includes a background white ink application step of applying background white ink onto the primer layer, and a fourth irradiation step of irradiating the background white ink applied onto the primer layer with active energy rays.

In the background white ink deposition process, after the first irradiation process, as shown in FIG. 5, the three-dimensional object 1 is transported in the transport direction C, and when it moves into the ink landing range of the background white ink ejection head 131, background white ink is ejected from the background white ink ejection head 131. This causes the background white ink to adhere to the cured primer of the three-dimensional object 1.

The three-dimensional object 1 with the white background ink attached thereto is transported in the transport direction C and moves into the irradiation range of the active energy rays from the fourth irradiation device 132. In the fourth irradiation step, the active energy rays are irradiated from the fourth irradiation device 132. In the fourth irradiation step, the active energy rays from the fourth irradiation device 132 may be pinning exposure or main exposure. Of these, it is more preferable that in the fourth irradiation step, the active energy rays from the fourth irradiation device 132 are pinning exposure. By curing the white background ink prior to the ink in the colored portion, the colored ink can be fixed more stably on the background printed portion. As a result, a clearer image can be obtained.

In this embodiment, it is preferable to pre-cure two or more types of color inks together and then fully cure them.

In each of the first, second, third and fourth irradiation steps, the reaction rate of the color ink after pinning exposure is lower than the reaction rate of the color ink after the main exposure. The reaction rate of the color ink after pinning exposure is not particularly limited, but is preferably 10 to 80%, and more preferably 15 to 75%. By setting it in such a range, the image quality of the obtained image is improved. The reaction rate of the color ink after the main exposure is not particularly limited, but is preferably more than 80% and 100% or less, and more preferably 85 to 100%. The reaction rate of the color ink is determined by the following method. A substrate is prepared that has been subjected to operations until the end of irradiation of the ink with active energy rays. A sample piece (hereinafter referred to as a post-irradiation sample piece) having a size of 20 mm x 50 mm is cut out from the region where the ink film of this substrate exists. The cut-out post-irradiation sample piece is immersed in 10 mL of THF (tetrahydrofuran) for 24 hours to obtain an eluate in which the ink is eluted. The amount of polymerizable monomer in the obtained eluate (hereinafter referred to as "post-irradiation monomer amount X1") is determined by high performance liquid chromatography. Separately, the same operation as above is carried out except that the ink on the substrate is not irradiated with active energy rays, and the amount of polymerizable monomer (hereinafter referred to as "non-irradiation monomer amount X1") is determined. Based on the post-irradiation monomer amount X1 and the non-irradiation monomer amount X1, the reaction rate (%) of the ink is calculated by the following (Equation 1).
(Formula 1) Ink reaction rate (%)=((amount of monomer before irradiation X1−amount of monomer after irradiation X1)/amount of monomer before irradiation X1)×100

The exposure amount of the active energy rays for the pinning exposure is preferably 0.1 to 100 mJ/ ^cm2 , and more preferably 0.2 to 60 mJ/ ^cm2 . By setting it in such a range, the color ink can be pinned. The exposure amount of the active energy rays for the main exposure is preferably 0.3 to 1000 mJ/ ^cm2 , and more preferably 0.5 to 800 mJ/ ^cm2 . By setting it in such a range, the color ink can be completely cured.

In the method for manufacturing a three-dimensional object according to the present embodiment, the time from the end of the primer ink application process to the start of irradiation of active energy rays in the first irradiation process is preferably longer than the time from the end of the color ink application process to the start of irradiation of active energy rays in the second irradiation process. The time from the end of the color ink application process to the start of irradiation of active energy rays in the second irradiation process is the time from the time when the entire amount of color ink set from the color ink ejection head (the fourth color ink ejection head 114 in FIG. 4) arranged at the most downstream of the conveying path 106 in the color ink application process has landed on the cured product of the primer ink to the time when irradiation of active energy rays is started in the second irradiation device 122. The primer layer obtained by leveling the primer ink is made flat, while the bleeding of the color ink is suppressed, and a clearer image can be obtained. By lengthening the time from the end of the primer ink application process to the start of irradiation of active energy rays in the first irradiation process, the primer ink can be leveled. There are no particular limitations on the method for lengthening the time from the primer ink application step to the start of irradiation of active energy rays in the first irradiation step, but examples include a method of lengthening the transport distance of the three-dimensional object 1, and a method of rotating the three-dimensional object 1 on the spot after the primer ink is applied and holding it until the primer ink levels out. The time from the point at which the set amount of primer ink has landed on the outer surface of the three-dimensional object 1 in the primer ink application step to the start of irradiation of active energy rays in the first irradiation step is preferably 2 to 10 times, more preferably 2.5 to 8 times, and even more preferably 3 to 5 times, the time from the end of the color ink application step to the start of irradiation of active energy rays in the second irradiation step.

The time from the time when the entire amount of the primer ink has landed on the outer surface of the three-dimensional object 1 in the primer ink application process to the time when the irradiation of the active energy rays begins in the first irradiation process is preferably 0.5 to 60 seconds, and more preferably 1.0 to 10 seconds. By setting it in such a range, the primer ink can be sufficiently leveled. On the other hand, the time from the time when the entire amount of the color ink discharged from the color ink discharge head at the most downstream of the transport path 6 (for example, the fourth color ink discharge head 114 in FIG. 4) has landed on the primer cured product in the color ink application process to the time when the irradiation of the active energy rays begins in the second irradiation process is preferably 0.1 to 60 seconds, and more preferably 0.3 to 1.0 seconds. By setting it in such a range, bleeding between the color inks can be further suppressed.

In the method for manufacturing a three-dimensional object according to this embodiment, it is even more preferable that the time from the end of the primer ink application step to the start of irradiation with active energy rays in the first irradiation step is longer than the time from the point at which the set total amount of color ink ejected from the color ink ejection head most upstream of the transport path 6 (for example, the first color ink ejection head 111 in FIG. 4) has landed on the cured primer product in the color ink application step to the start of irradiation with active energy rays in the second irradiation step. The primer layer obtained by leveling the primer ink can be made flatter, while the bleeding of the color ink can be further suppressed, resulting in a clearer image.

In this embodiment, the time from the time when the set amount of color ink ejected from the color ink ejection head most upstream of the transport path 6 (for example, the first color ink ejection head 111 in FIG. 4) has landed on the cured primer material in the color ink attachment process to the time when the irradiation of active energy rays in the second irradiation process begins is preferably 0.2 to 60 seconds, and more preferably 0.4 to 1.0 seconds. By setting it in such a range, it is possible to further suppress bleeding between color inks. The time from the time when the set amount of primer ink has landed on the outer surface of the three-dimensional object 1 in the primer ink attachment process to the time when the irradiation of active energy rays in the first irradiation process begins is preferably 2 to 10 times the time from the time when the set amount of color ink ejected from the color ink ejection head most upstream of the transport path 6 has landed on the cured primer material in the color ink attachment process to the time when the irradiation of active energy rays in the second irradiation process begins.

In the manufacturing method of a three-dimensional object according to this embodiment, the three-dimensional object 1 has a bottom surface and a side surface, and is transported with the bottom surface facing the transport device 105 with the side surface standing up, and the primer ink ejection head 101 and the color ink ejection heads 111, 112, 113, and 114 of the ejection head unit 110 preferably eject ink onto the side surface of the three-dimensional object 1. Here, transporting with the side surface standing up means that, for example, when the three-dimensional object 1 is a container as shown in FIG. 1, the container is transported with its central axis facing vertically. In this way, by transporting the three-dimensional object 1 in an upright state, the manufacturing device 100 can be made smaller. In addition, the printing portion 20 can be formed on the side surface of the three-dimensional object 1 more efficiently.

1 Three-dimensional object 10 Container body 11 Mouth 12 Body 12a Upper body 12b Body body 12c Lower body 20 Printing section 21 Primer layer 22 Ink layer 22A Coloring section 22B Background printing section 100 Three-dimensional object manufacturing device 101 Primer ink ejection head 105 (105a, 105b, 105c) Transport device 106 Transport path 110 Ejection head unit 111 First color ink ejection head 112 Second color ink ejection head 113 Third color ink ejection head 114 Fourth color ink ejection head 121 First irradiation device 122 Second irradiation device 123 Third irradiation device 130 Background printing section forming unit 131 Background white ink ejection head 132 Fourth irradiation device C Transport direction

Claims (9)

1. An apparatus for manufacturing a three-dimensional object, which forms a printed portion having a primer layer and an ink layer provided on an outer surface of a three-dimensional object,
the primer layer includes a cured product of a primer ink that is an active energy ray-curable inkjet ink,
the ink layer has a color portion, the color portion including a cured product of a color ink that is an active energy ray-curable ink-jet ink containing a color material;
The color ink includes at least a first color ink and a second color ink having a different color from the first color ink,
The three-dimensional object manufacturing apparatus comprises:
a primer ink ejection head that ejects the primer ink;
A first irradiation device;
an ejection head unit including a first color ink ejection head that ejects the first color ink and a second color ink ejection head that ejects the second color ink;
A second irradiation device;
and a conveying device that conveys the three-dimensional object in this order. The three-dimensional object manufacturing apparatus according to claim 1, further comprising a third irradiation device disposed downstream of the conveying device relative to the second irradiation device. The ink layer further includes a background printing portion between the primer layer and the color portion,
the background printed portion includes a cured product of a background white ink, which is an active energy ray-curable inkjet ink containing a white colorant;
the three-dimensional object manufacturing apparatus further includes a background printing unit between the first irradiation device and the ejection head unit,
The background printing unit includes:
a background white ink ejection head that ejects the background white ink;
A fourth irradiation device;
3. The apparatus for manufacturing a three-dimensional object according to claim 1, further comprising: The three-dimensional object manufacturing device according to claim 1 or 2, characterized in that the transport distance of the three-dimensional object of the transport device between the primer ink ejection head and the first irradiation device is longer than the transport distance of the three-dimensional object of the transport device between the ejection head unit and the second irradiation device. A method for manufacturing a three-dimensional object, comprising forming a printed portion having a primer layer and an ink layer provided on the primer layer on an outer surface of the three-dimensional object, comprising:
the primer layer includes a cured product of a primer ink that is an active energy ray-curable inkjet ink,
the ink layer has a color portion, the color portion including a cured product of a color ink that is an active energy ray-curable ink-jet ink containing a color material;
The color ink includes at least a first color ink and a second color ink having a different color from the first color ink,
The method for manufacturing the three-dimensional object includes the steps of:
a color ink applying step including at least a first color ink applying step of applying the first color ink onto the cured product of the primer ink, and a second color ink applying step of applying the second color ink onto the cured product of the primer ink;
a second irradiation step of irradiating with active energy rays a group of color inks including the first color ink and the second color ink adhered onto the cured product of the primer ink in the color ink adherence step;
A method for manufacturing a three-dimensional object, comprising the steps of: In the method for producing a three-dimensional object, before the color ink application step,
a primer ink applying step of applying the primer ink to an outer surface of the three-dimensional object;
a first irradiation step of irradiating the primer ink attached to the outer surface of the three-dimensional object with active energy rays;
The method for manufacturing a three-dimensional object according to claim 5, further comprising: The method for manufacturing the three-dimensional object includes the steps of:
After the second irradiation step,
6. The method for producing a three-dimensional object according to claim 5, further comprising a third irradiation step of further irradiating the color inks with active energy rays. The ink layer further has a background printed portion between the primer layer and the cured product of the color ink,
the background printed portion includes a cured product of a background white ink, which is an active energy ray-curable inkjet ink containing a white colorant;
The method for manufacturing a three-dimensional object further includes a background printing portion forming step between the first irradiation step and the color ink applying step,
The background printing portion forming step includes:
a background white ink applying step of applying the background white ink onto the primer layer;
a fourth irradiation step of irradiating the background white ink attached on the primer layer with active energy rays;
The method for manufacturing a three-dimensional object according to claim 6, further comprising the steps of: The method for manufacturing a three-dimensional object according to claim 6, characterized in that the time from the end of the primer ink application process to the start of irradiation of the active energy rays in the first irradiation process is longer than the time from the end of the color ink application process to the start of irradiation of the active energy rays in the second irradiation process.

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