WO2015105047A1

WO2015105047A1 - Method for manufacturing three-dimensional structure and three-dimensional structure

Info

Publication number: WO2015105047A1
Application number: PCT/JP2015/000039
Authority: WO
Inventors: Eiji Okamoto
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2014-01-09
Filing date: 2015-01-07
Publication date: 2015-07-16
Anticipated expiration: 2016-07-09
Also published as: TW201527064A; JP2015128884A

Abstract

The present invention relates to a method for manufacturing a three-dimensional structure by stacking layers, and which includes an ink discharge step of discharging an ink for forming an outermost layer to a region to become the outermost layer of the three-dimensional structure of the layer and discharging an ink for forming a sacrificial layer for forming a sacrificial layer to a region on a surface side of the layer which is adjacent to the region to become the outermost layer of the layer, a curing step of curing the ink for forming an outermost layer and the ink for forming a sacrificial layer discharged, and a filling step of filling a region surrounded by a cured product of the ink for forming an outermost layer with a composition for forming a three-dimensional object including powder for forming a three-dimensional object configured of a plurality of particles and forming a composition layer for forming a three-dimensional object.

Description

METHOD FOR MANUFACTURING THREE-DIMENSIONAL STRUCTURE AND THREE-DIMENSIONAL STRUCTURE

The present invention relates to a method for manufacturing a three-dimensional structure and a three-dimensional structure.

In the related art, a method for forming a three-dimensional structure is known based on a model of a three-dimensional object, for example, generated by three-dimensional CAD software or the like.

As one method for forming a three-dimensional structure, a stacking method is known. In the stacking method, in general, after splitting the model of a three-dimensional object into a large number of two-dimensional cross-sectional layers, a three-dimensional structure is formed by sequentially stacking cross-section members while sequentially forming the cross-section members corresponding to each two-dimensional cross-sectional layer.

By the stacking method, a three-dimensional structure can be formed immediately as long as there is a model of a three-dimensional structure to be formed, and since there is no need to make a die before forming, it is possible to quickly and inexpensively form a three-dimensional structure. In addition, since a three-dimensional structure is formed by stacking cross-section members having a thin plate-shape layer by layer, for example, even in a case where the object has a complex internal structure, it is possible to form a formed object as one piece without being divided into a plurality of parts.

As one of such stacking methods, a technology for forming a three-dimensional structure while hardening a powder with a binding liquid is known (for example, refer to PTL 1). In this technique, when each layer is formed, by discharging an ink containing a colorant to the location corresponding to the outer surface side of a three-dimensional structure, the three-dimensional structure is colored.

However, since in the above method in which a powder is hardened, a powder is used, there is a problem in which the outer surface is brittle. In addition, due to unevenness caused by the powder, it is difficult to perform a fine color expression on the outer surface.

On the other hand, as one of such stacking methods, a technology for forming a three-dimensional structure while hardening a discharged ink itself is known (for example, refer to PTL 2). In this technique, it is possible to form each layer thinly, and it is possible to perform a variety of color expression on the outer surface. In addition, since a powder is not used, it is possible to exhibit a high strength as a whole.

Although in the above method in which an ink is hardened, there is no problem when making a small three-dimensional structure, when manufacturing a three-dimensional structure having a large size to some extent, there is a problem that too much time is taken.

JP-A-2001-150556 JP-A-2000-280354

An object of the invention is to provide a method for manufacturing a three-dimensional structure in which a three-dimensional structure of which the outer surface has high mechanical strength and on which a fine color expression is performed can be stably and efficiently manufactured, and a three-dimensional structure of which the outer surface has high mechanical strength and on which a fine color expression is performed.

Such an object is achieved using the invention described below.

According to a first aspect of the invention, there is provided a method for manufacturing a three-dimensional structure by stacking layers formed by using an ink containing a curable resin, and includes an ink discharge step of discharging an ink for forming an outermost layer in a region to become the outermost layer of the three-dimensional structure of the layer and discharging an ink for forming a sacrificial layer in a region on a surface side of the outermost layer which is adjacent to the region to become the outermost layer of the layer, a curing step of curing the ink for forming an outermost layer and the ink for forming a sacrificial layer discharged, and a filling step of filling a region surrounded by a cured product of the ink for forming an outermost layer with a composition for forming a three-dimensional object including powder for forming a three-dimensional object configured of particles and forming a composition layer for forming a three-dimensional object.

Thereby, it is possible to stably and efficiently manufacture a three-dimensional structure of which the outer surface has high mechanical strength and on which a fine color expression is performed.

In the method for manufacturing a three-dimensional structure of the invention, in the filling step, a planarization treatment is preferably performed with respect to the filled composition for forming a three-dimensional object based on the height of the cured product of the ink for forming an outermost layer.

Thereby, it is possible to greatly increase the dimensional accuracy of the finally obtained three-dimensional structure, and it is possible to more favorably control the surface shape of the three-dimensional structure and the appearance.

In the method for manufacturing a three-dimensional structure of the invention, a powder binding step of discharging a binding ink containing a curable resin and forming a powder binding layer is preferably performed with respect to the composition layer for forming a three-dimensional object.

Thereby, it is possible to make the mechanical strength of the finally obtained three-dimensional structure excellent.

In the method for manufacturing a three-dimensional structure of the invention, the powder binding step in formation of the layer of the kth layer (k is an integer of equal to or greater than 1) is preferably performed together with the ink discharge step in formation of the layer of the (k+1)th layer (k is an integer of equal to or greater than 1).

Thereby, it is possible to perform formation of the powder binding layer, and formation of the outermost layer and the sacrificial layer of a unit layer on one layer almost at the same time, and it is possible to more efficiently manufacture a three-dimensional structure.

In the method for manufacturing a three-dimensional structure of the invention, in the ink discharge step, the ink for forming an outermost layer is preferably discharged in a region to become the outermost layer of the three-dimensional structure of the plurality of the layers, and the ink for forming a sacrificial layer is preferably discharged in a region on a surface side of the outermost layer which is adjacent to the region to become the outermost layer of the plurality of the layers.

Thereby, it is possible to form a thin outermost layer regardless of the size of the particles of the powder for forming a three-dimensional object configuring a composition for forming a three-dimensional object. As a result, it is possible to form a three-dimensional structure capable of expressing finer colors and textures by the outer surface.

In the method for manufacturing a three-dimensional structure of the invention, the ink for forming an outermost layer preferably includes one type or two or more types selected from the group consisting of 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, polyether-based aliphatic urethane (meth)acrylate oligomer, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

Thereby, it is possible to cure the ink for forming an outermost layer at a more suitable curing rate, and it is possible to make productivity of a three-dimensional structure excellent.

In the method for manufacturing a three-dimensional structure of the invention, the ink for forming a sacrificial layer preferably includes one type or two or more types selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, polyethylene glycol di(meth)acrylate, (meth)acryloyl morpholine, and 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.

Thereby, it is possible to cure the ink for forming a sacrificial layer at a more suitable curing rate, it is possible to more reliably obtain an appearance of a fine texture in a three-dimensional structure, and it is possible to make productivity of a three-dimensional structure excellent.

In the method for manufacturing a three-dimensional structure of the invention, the ink for forming an outermost layer and the ink for forming a sacrificial layer preferably include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and/or 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a polymerization initiator.

Thereby, it is possible to cure the ink for forming an outermost layer and the ink for forming a sacrificial layer at a more suitable curing rate, and it is possible to make productivity of a three-dimensional structure excellent.

In the method for manufacturing a three-dimensional structure of the invention, as the ink for forming an outermost layer, in addition to a coloring ink containing a colorant, a colorless ink not containing a colorant is preferably used, the colorless ink is preferably used for forming a region near the outer surface of the three-dimensional structure, of the outermost surface, and the coloring ink is preferably used for forming a region on the inner side than that region.

Though the portion containing a colorant (in particular, a pigment) is likely to be brittle, become scratched, or become chipped compared to the portion not containing a colorant, by providing a region formed by using the ink for forming an outermost layer not containing a colorant near the outer surface of a three-dimensional structure, it is possible to effectively prevent the occurrence of such problems.

In the method for manufacturing a three-dimensional structure of the invention, as the ink for forming an outermost layer, a coloring ink containing a colorant is preferably used, a chromatic color ink and a white ink are preferably used as the coloring ink, and the white ink is preferably used for forming a region on the inner side of the region formed by using the chromatic color ink.

Thereby, a region (first region) where a white ink is applied can exhibit a concealing property, and it is possible to further increase color saturation of a three-dimensional structure.

According to the second aspect of the invention, there is provided a three-dimensional structure which is manufactured using the method for manufacturing a three-dimensional structure according to the aspect.

Thereby, it is possible to provide a three-dimensional structure of which the outer surface has high mechanical strength and on which a fine color expression is performed.

Fig. 1A is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 1B is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 1C is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 1D is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 2E is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 2F is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 2G is a cross-sectional view schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 3A is a cross-sectional view schematically showing a part of a step in another embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 3B is a cross-sectional view schematically showing a part of a step in another embodiment of the method for manufacturing a three-dimensional structure of the invention. Fig. 4 is a cross-sectional view schematically showing a state in a layer (composition for forming a three-dimensional object) immediately before an ink discharge step. Fig. 5 is a cross-sectional view schematically showing a state in which particles are bound to each other by a curable resin. Fig. 6 is a schematic diagram showing a three-dimensional structure manufacturing apparatus for manufacturing a three-dimensional structure. Fig. 7 is a block diagram of a control portion included in the three-dimensional structure manufacturing apparatus shown in Fig. 6.

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

(1. Method for Manufacturing Three-dimensional Structure)
First, the method for manufacturing a three-dimensional structure of the invention will be described.

Fig. 1A to Fig. 1D and Fig. 2E to Fig. 2G are cross-sectional views schematically showing each step in a preferred embodiment of the method for manufacturing a three-dimensional structure of the invention, Fig. 3A and Fig. 3B are cross-sectional views schematically showing a part of a step in another embodiment of the method for manufacturing a three-dimensional structure of the invention, Fig. 4 is a cross-sectional view schematically showing a state in a layer (composition for forming a three-dimensional object) immediately before the ink discharge step, and Fig. 5 is a cross-sectional view schematically showing a state in which particles are bound to each other by a curable resin.

As shown in Fig. 1A to Fig. 1D and Fig. 2E to Fig. 2G, the method for manufacturing a three-dimensional structure 1 of the embodiment has an ink discharge step (Fig. 1A and Fig. 1C, and Fig. 2E) of discharging an ink for forming an outermost layer 4A including a curable resin and an ink for forming a sacrificial layer 4B including a curable resin in a predetermined pattern by an ink jet method, a curing step (Fig. 1A and Fig. 1C, and Fig. 2E) of curing the curable resin included in the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B discharged and forming an outermost layer 7 and a sacrificial layer 8, a filling step (Fig. 1B and Fig. 1D) of filling a region surrounded by the outermost layer 7 with a composition for forming a three-dimensional object including powder for forming a three-dimensional object configured of a plurality of particles and forming a composition layer for forming a three-dimensional object 6', and a powder binding step (Fig. 1C and Fig. 2E) of discharging a binding ink containing a curable resin with respect to the composition layer 6' for forming a three-dimensional object, and these steps are sequentially and repeatedly performed, then, the ink for forming an outermost layer 4A is discharged in a region at which the outermost layer of the three-dimensional structure 1 is to be configured. In addition, the ink for forming a sacrificial layer 4B is discharged in a region on the surface side of the outermost layer which is adjacent to the region to become the outermost layer of the three-dimensional structure 1.

The method for manufacturing a three-dimensional structure 1 according to the embodiment has a characteristic in which a composition for forming a three-dimensional object including powder for forming a three-dimensional object is filled in a region surrounded by the outermost layer 7 and the sacrificial layer 8 formed by the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B as described above.

In this manner, by forming the outermost layer 7 using only the ink for forming an outermost layer 4A, it is possible to increase the mechanical strength of the outer surface compared to a three-dimensional structure formed by hardening powder in the related art. In addition, it is possible to perform a fine color expression.

In addition, since the inside of the three-dimensional structure 1 is formed using a composition for forming a three-dimensional object including powder for forming a three-dimensional object, it is possible to stably and efficiently manufacture the three-dimensional structure 1 compared to a method for manufacturing the three-dimensional structure 1 using only an ink.

In addition, by forming the sacrificial layer 8 on the outside of the outermost layer 7 of the three-dimensional structure 1, it is possible to prevent the ink for forming an outermost layer 4A from flowing out, and it is possible to express finer colors and textures on the outer surface of the three-dimensional structure 1.

Hereinafter, each step will be described.

(Ink Discharge Step (Ink Applying Step))
In the ink discharge step, the ink for forming an outermost layer 4A including a curable resin and the ink for forming a sacrificial layer 4B including a curable resin are discharged on a forming stage 80 in a predetermined pattern by an ink jet method (Fig. 1A and Fig. 1C).

More specifically, the ink for forming an outermost layer 4A is applied to the region to become the outermost layer 7 of the three-dimensional structure 1, and the ink for forming a sacrificial layer 4B is applied to the region of the surface side of the outermost layer 7 which is adjacent to the region to become the outermost layer 7 of the three-dimensional structure 1.

In the first ink discharge step, the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) is discharged on the forming stage 80 (Fig. 1A), and in the second or subsequent ink discharge steps, the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) is discharged on the outermost layer 7 and the sacrificial layer 8 (Fig. 1C and Fig. 2E).

In this manner, in the invention, the outermost layer 7 is formed by applying the ink for forming an outermost layer 4A to the portion to become the outermost layer of the three-dimensional structure 1, and the sacrificial layer 8 is formed by applying the ink for forming a sacrificial layer 4B to the region on the outside of the outermost layer 7.

With this configuration, it is possible to increase the mechanical strength of the outer surface compared to a three-dimensional structure formed by hardening powder in the related art. In addition, it is possible to perform a fine color expression. In addition, it is possible to prevent the ink for forming an outermost layer 4A from flowing out, and it is possible to express finer colors and textures on the outer surface of the three-dimensional structure 1.

In addition, in this step, since the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) is applied by an ink jet method, it is possible to reproducibly apply even in a case where the applying pattern of the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) has a fine shape. As a result, it is possible to greatly increase the dimensional accuracy of the finally obtained three-dimensional structure 1, and it is possible to more favorably control the surface shape of the three-dimensional structure 1 and the appearance.

Moreover, the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B will be described in detail.

(Curing Step)
After the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) is applied (discharged) in the ink discharge step, the curing component (curable resin) included in the ink (the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B) is cured (Fig. 1B and Fig. 1D). Thereby, the outermost layer 7 and the sacrificial layer 8 are obtained.

In this step, the outer surface of the three-dimensional structure 1 finally obtained by curing the curing component (curable resin) included in the ink is a surface configured of a cured product. Therefore, the surface has excellent mechanical strength and an excellent durability, for example, compared to a three-dimensional structure configured of a thermoplastic resin.

Depending on the types of curing component (curable resin), for example, in a case where the curing component (curable resin) is a thermosetting resin, this step can be performed by heating, and in a case where the curing component (curable resin) is a photocurable resin, this step can be performed by irradiation of the corresponding light (for example, in a case where the curing component (curable resin) is an ultraviolet ray curable resin, this step can be performed by irradiation of ultraviolet rays).

Moreover, in the above description, the ink is applied in the shape and the pattern corresponding to the outermost layer 7 and the sacrificial layer 8, and thereafter, all the layers configured of the ink are cured, however, in the invention, regarding at least a part of a region, discharging of the ink and curing of the ink may be performed at the same time. That is, before the entire patterns of one outermost layer 7 and the entire sacrificial layers 8 are formed, regarding at least a part of the region corresponding to the outermost layer 7 and the sacrificial layer 8, the sequential curing reaction may proceed from the portion to which the ink is applied.

In addition, in this step, it is not necessary to completely cure the curing component included in the ink. For example, at the time when this step ends, the ink for forming a sacrificial layer 4B may be in an incompletely cured state, and the ink for forming an outermost layer 4A may be cured to a higher degree of cure than that of the ink for forming a sacrificial layer 4B.

Thereby, it is possible to easily perform a sacrificial layer removing step described below in detail, and it is possible to further improve productivity of the three-dimensional structure 1.

In addition, at the time when this step ends, the ink for forming an outermost layer 4A may be in an incompletely cured state. Even in such a case, for example, after the following step (for example, "ink discharge step" or the like after the outermost layer 7 and the sacrificial layer 8 of the lower layer in the curing step are formed) is performed, by performing the main curing treatment for increasing the degree of cure regarding the ink for forming an outermost layer 4A which is in an incomplete cured state, it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent. In addition, by applying an ink for forming an upper layer in the state in which the ink for forming an outermost layer 4A (lower layer) is in an incompletely cured state, it is possible to make the adhesion between the layers excellent.

(Filling Step)
Next, the region surrounded by the cured product of the ink for forming an outermost layer 4A, that is, the region surrounded by the outermost layer 7 is filled with the composition for forming a three-dimensional object including powder for forming a three-dimensional object configured of a plurality of particles, whereby the composition layer for forming a three-dimensional object 6' is formed.

In this manner, since the inside of the three-dimensional structure 1 is formed using the composition for forming a three-dimensional object including powder for forming a three-dimensional object, it is possible to stably and efficiently manufacture the three-dimensional structure 1 compared to a method for manufacturing the three-dimensional structure 1 using only an ink.

This step can be performed by using a method such as a squeegee method, a screen printing method, a doctor blade method, a spin coating method, or the like.

In addition, in this step, a planarization treatment is performed with respect to the composition for forming a three-dimensional object applied to the region surrounded by the outermost layer 7 based on the height of the cured product of the ink for forming an outermost layer. Thereby, it is possible to form a unit layer (layer configured of the outermost layer 7 and a powder binding layer 6 described below) having a more uniform thickness. As a result, it is possible to greatly increase the dimensional accuracy of the finally obtained three-dimensional structure 1, and it is possible to more favorably control the surface shape and the appearance of the three-dimensional structure 1.

The composition for forming a three-dimensional object, as described below in detail, includes a water-soluble resin 64 together with a plurality of particles 63. By including the water-soluble resin 64, the particles 63 are bound (temporarily fixed) to each other (Fig. 4), and it is possible to effectively prevent unintended scattering of the particles. Thereby, it is possible to improve safety of a worker and the dimensional accuracy of the manufactured three-dimensional structure 1.

Moreover, for example, in a case where the composition for forming a three-dimensional object reaches a solid state (pellet form) (for example, a case in which the composition for forming a three-dimensional object includes a water-soluble resin (thermoplastic resin) 64 which reaches a solid state near the storage temperature (for example, room temperature (25 degrees centigrade)), and the plurality of particles 63 reach a state of being bound by the water-soluble resin), before forming the layers as described above, the composition for forming a three-dimensional object is melted by heating, and due to this, the composition for forming a three-dimensional object may be in a state having fluidity. Thereby, it is possible to efficiently fill by a simple method as described above. As a result, it is possible to manufacture the three-dimensional structure 1 having a higher dimensional accuracy, with a higher productivity.

(Powder Binding Step)
Next, a binding ink 4C including a curable resin 44 is discharged with respect to the composition layer for forming a three-dimensional object 6 ' formed in the filling step (Fig. 1C and Fig. 2E). By curing the curable resin in the discharge binding ink 4C, the powder binding layer 6 is formed, and the unit layer configured of the outermost layer 7 and the powder binding layer 6 is formed.

In addition, by this step, it is possible to more strongly bind the particles 63 configuring the composition layer for forming a three-dimensional object 6 to each other by the curable resin 44, and it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent. In addition, in a case where the composition for forming a three-dimensional object configuring the composition layer for forming a three-dimensional object 6 includes a plurality of the porous particles 63, the curable resin 44 enters into a pore 611 of the particles 63 and an anchoring effect is exhibited, and as a result, it is possible to make a binding force of the binding of the particles 63 to each other (binding force through the curable resin 44) excellent, and it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent (see Fig. 5).

As shown in Fig. 1C and Fig. 2E, this step is preferably performed together with the ink discharge step of the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B in formation of the unit layer being one higher than the unit layer formed. In other words, the powder binding step in formation of the unit layer of the kth layer (k is an integer of equal to or greater than 1) is preferably performed together with the ink discharge step in formation of the unit layer of the (k+1)th layer (k is an integer of equal to or greater than 1). Thereby, it is possible to perform formation of the powder binding layer 6, and formation of the outermost layer 7 and the sacrificial layer 8 of a unit layer on one layer almost at the same time, and it is possible to more efficiently manufacture the three-dimensional structure 1.

Moreover, as the binding ink 4C, the same ink as the ink for forming an outermost layer 4A described below in detail can be used.

The series of steps described above is repeated, and the outermost layer 7 is formed on the upper surface in the unit layer direction of the three-dimensional structure 1 with the ink for forming an outermost layer 4A. Thereby, a state in which the adjacent unit layers (layer configured of the outermost layer 7 and the powder binding layer 6) are bound to each other is formed, and a temporarily formed body 1' in which the sacrificial layer 8 is provided on the surface of the laminate in which the unit layers in such a state are multiply stacked is obtained (see Fig. 2F).

(Sacrificial Layer Removing Step)
After the series of steps as described above is repeatedly performed, the sacrificial layer 8 is removed from the temporarily formed body 1' (see Fig. 2G).

Thereby, the three-dimensional structure 1 is obtained.

As a method for removing the sacrificial layer 8, a method in which the sacrificial layer 8 is selectively dissolved and removed by using a liquid which selectively dissolves the sacrificial layer 8, a method in which by selectively absorbing the liquid in the sacrificial layer 8 using a liquid which is more strongly absorbed by the sacrificial layer 8 than the outermost layer 7, the sacrificial layer 8 swells, or by reducing the mechanical strength of the sacrificial layer 8, the sacrificial layer 8 is peeled or is destroyed, and the like can be exemplified.

The liquid used in this step varies depending on the constituent materials of the outermost layer 7 and the sacrificial layer 8, and for example, water, alcohols such as methanol, ethanol, and isopropyl alcohol, and glycols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol can be used. The liquid contains one type or two or more types selected from these, and into this liquid, a water-soluble substance producing hydroxide ions such as sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, or an organic amine to increase the solubility of the sacrificial layer and a surfactant to facilitate separation of the peeled sacrificial layer may be mixed.

The method for applying the liquid is not particularly limited, and for example, an immersion method, a spraying method, a coating method, various printing methods, or the like can be adopted.

In addition, though in the above description, techniques using a liquid are described, substances having the same function (for example, solid, gas, supercritical fluid, or the like) may be used.

In addition, when applying the liquid to the temporarily formed body 1' or after applying the liquid, ultrasonic vibration may be applied. Thereby, it is possible to promote the removal of the sacrificial layer 8, and it is possible to make productivity of the three-dimensional structure 1 excellent.

Moreover, though in the embodiment described above, it is described that after the outermost layer 7 and the sacrificial layer 8 of one unit layer portion are formed, the region surrounded by the outermost layer 7 is filled with the composition for forming a three-dimensional object, the invention is not limited thereto, and for example, as shown in Fig. 3A and Fig. 3B, a constitution in which after the outermost layer 7 and the sacrificial layer 8 of a plurality of the unit layer portions are formed, the region surrounded by a plurality of the outermost layers 7 is filled with the composition for forming a three-dimensional object may be used. Thereby, it is possible to form a thin outermost layer 7 regardless of the size of the particles of the powder for forming a three-dimensional object configuring a composition for forming a three-dimensional object. As a result, it is possible to form the three-dimensional structure 1 capable of expressing finer colors and textures by the outer surface.

(2. Three-dimensional Structure Manufacturing Apparatus)
Next, a three-dimensional structure manufacturing apparatus 100 according to the embodiment will be described.

Fig. 6 is a schematic diagram showing a three-dimensional structure manufacturing apparatus for manufacturing a three-dimensional structure. Fig. 7 is a block diagram of a control portion included in the three-dimensional structure manufacturing apparatus shown in Fig. 6.

The three-dimensional structure manufacturing apparatus 100 is an apparatus which is applied to the method for manufacturing a three-dimensional structure, and is an apparatus in which a model of a unit layer (the outermost layer 7 and the powder binding layer 6) and the sacrificial layer 8 is produced, and by sequentially stacking each unit layer, the three-dimensional structure 1 is formed while sequentially forming each layer based on the model.

As shown in Fig. 6 and Fig. 7, the three-dimensional structure manufacturing apparatus 100 has a computer 20 for performing production or the like of a model of a unit layer or the like and a forming portion 30 for forming the three-dimensional structure 1.

Hereinafter, each portion configuring the three-dimensional structure manufacturing apparatus 100 will be described in detail.

(Forming Portion 30)
As shown in Fig. 6, the forming portion 30 is equipped with an ink discharge portion (ink discharge means) 40 which is electrically connected to the computer 20, a powder supply portion 50, a powder control portion 60, a light source 70, and the forming stage 80.

The ink discharge portion 40 has a liquid droplet discharge head 41 for discharging liquid droplets of the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B, and the binding ink 4C by an ink jet method. In addition, the ink discharge portion 40 is equipped with an ink supply portion which is not shown in the figure. In the embodiment, the droplet discharge head 41 which uses a so-called piezoelectric driving method is adopted. The droplet discharge head 41 is configured to be able to change the discharge amount of the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B according to the instructions of a control portion 21 described below.

In addition, the ink discharge portion 40 has an X-direction moving portion 42 and a Y-direction moving portion 43 for moving the droplet discharge head 41 on an XY plane.

The powder supply portion 50 has a function of supplying powder for forming a three-dimensional object (composition for forming a three-dimensional object) to the forming stage 80 described below. The powder supply portion 50 is configured to be driven by powder supply portion driving means which is not shown in the figure.

The powder control portion 60 is equipped with a blade 61 and a guide rail 62 for controlling operation of the blade 61. The powder control portion 60 controls the composition for forming a three-dimensional object supplied from the powder supply portion 50 by the blade 61, and has a function of forming the composition for forming a three-dimensional object 6' configured of composition for forming a three-dimensional object in the region surrounded by the outermost layer 7 on the forming stage 80.

The blade 61 has a shape elongated in the Y-direction, and has a blade-like shape of which the lower tip is sharp. The blade 61 is configured to be driven in the X-direction along the guide rail 62 by blade driving means which is not shown in the figure.

Layer forming means is configured of the powder supply portion 50 and the powder control portion 60.

The light source 70 has a function of curing the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B, and the binding ink 4C discharged.

The light source 70 is configured to emit ultraviolet light. As the light source 70, for example, a mercury lamp, a metal halide lamp, a xenon lamp, or an excimer lamp can be adopted.

The forming stage 80 has a rectangular shape in the XY cross section. On this forming stage 80, the unit layer (the outermost layer 7 and the powder binding layer 6) and the sacrificial layer 8 are formed.

The forming stage 80 is movable in the Z-direction by a forming stage driving means which is not shown in the figure.

The forming stage 80 moves downward by as much as the thickness of the formed outermost layer 7, and by the powder supply portion 50 and the powder control portion 60, the composition layer for forming a three-dimensional object 6' is formed in the region surrounded by the outermost layer 7.

In addition, the forming portion 30 is equipped with a driving control portion which is not shown in the figure.

The driving control portion has a motor control portion, a position detection control portion, a powder supply control portion, a discharge control portion, and an exposure control portion.

The motor control portion separately controls driving in the XY-direction of the liquid droplet discharge head 41, driving of the blade 61, and driving of the forming stage 80 based on the instructions from a CPU of the computer 20 described below.

The position detection control portion separately controls the position of the liquid droplet discharge head 41, the position of the blade 61, and the position of the forming stage 80 based on the instructions from the CPU.

The powder supply control portion controls driving (supply of powder) of the powder supply portion 50 based on the instructions from the CPU.

The discharge control portion controls driving (discharge of liquid droplets) of the liquid droplet discharge head 41 based on the instructions from the CPU.

The exposure control portion controls the light emitting state of the light source 70 based on the instructions from the CPU.

(Computer 20)
As shown in Fig. 7, the computer 20 has a control portion 21 for controlling the operation of each portion of the forming portion 30, a receiving portion 24, and an image producing portion 25.

The control portion 21 has a CPU (Central Processing Unit) 22 and a memory portion 23.

The CPU 22 performs various computational processing as a processor, and executes a control program 231.

The memory portion 23 has a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In the memory portion 23, a region where the control program 231 in which the control procedure of operation in the forming portion 30 is recorded is stored, or a data expanding portion 232 which is a region where various types of data is temporarily expanded are set. The memory portion 23 is connected to CPU 22 through a data bus 29.

In addition, the control portion 21 is connected to the image producing portion 25 and the receiving portion 24 through the data bus 29. In addition, the control portion 21 is connected to the driving control portion of the forming portion 30 through an input/output interface 28 and the data bus 29. In addition, the driving control portion is connected to the above-described powder supply portion driving means, the forming stage driving means, the blade driving means, the liquid droplet discharge head, and the light source through the input/output interface 28 and the data bus 29, respectively.

The image producing portion 25 has a function of manufacturing a model or the like of the three-dimensional structure 1. The image producing portion 25 is configured of software or the like for producing a three-dimensional object such as three-dimensional CAD (computer-aided design).

The image producing portion 25 has a three-dimensional structure model producing function of producing a model of the three-dimensional structure 1, or a function of producing a two-dimensional model which expresses an outer surface or the like of a model of the three-dimensional structure 1 by a two-dimensional model of polygons such as a triangle or a quadrangle such as STL (Standard Triangulated Language). That is, the image producing portion 25 has a function of producing three-dimensional shape data of the three-dimensional structure 1.

In addition, the image producing portion 25 has a function of producing unit layer (the outermost layer 7 and the powder binding layer 6) data by cutting the model of the three-dimensional structure 1 into layers. In addition, the image producing portion 25 has a function of producing sacrificial layer data based on the unit layer data.

The unit layer data and the sacrificial layer data produced by the image producing portion 25 are stored at the memory portion 23, and transferred to the driving control portion of the forming portion 30 through the input/output interface 28 and the data bus 29. The forming portion 30 is driven based on the transferred unit layer data and sacrificial layer data.

The receiving portion 24 is equipped with a USB (Universal Serial BUS) port, a LAN port, and the like. The receiving portion 24 has a function of receiving the original object for producing a model of the three-dimensional structure 1 from an external device (not shown) such as a scanner or the like.

In addition, the computer 20 is connected to a monitor (display device), and a keyboard (input device) (not shown). The monitor and the keyboard are connected to the control portion 21 through the input/output interface and the data bus, respectively.

The monitor has a function of displaying an image file acquired by the receiving portion 24 in an image display region. Via the monitor, a worker can visually grasp the image file or the like.

Moreover, the input device is not limited to a keyboard, and the input device may be a mouse, a trackball, a touch panel, or the like.

(3. Ink Set (Ink for Forming an Outermost Layer 4A, Ink for Forming a Sacrificial Layer 4B, and Binding Ink 4C))
Hereinafter, an ink set will be described.

The ink set of the embodiment is equipped with at least one of the ink for forming an outermost layer 4A, the ink for forming a sacrificial layer 4B, and the binding ink 4C. The ink set of the embodiment is applied to the method for manufacturing a three-dimensional structure of the invention and the three-dimensional structure manufacturing apparatus as described above.

Moreover, the ink for forming an outermost layer 4A and the binding ink 4C are inks configured by the same components, and thus, only the ink for forming an outermost layer 4A will be described, and description of the binding ink 4C will be omitted.

(Ink for Forming Outermost Layer (Bonding Ink))
The ink for forming an outermost layer 4A includes at least a curable resin (curing component).

(Curable Resin 1)
Example of the curable resin (curing component) include a thermosetting resin; and various photocurable resins such as a visible light curable resin which is cured by light in the visible light region (photocurable resin in the narrow sense); an ultraviolet ray curable resin; an infrared ray curable resin; and an X-ray curable resin, and one type or two or more types selected from these can be used singly or in combination.

Among these, from the viewpoint of the mechanical strength of the obtained three-dimensional structure 1, productivity of the obtained three-dimensional structure 1, and storage stability of the ink for forming an outermost layer 4A, in particular, an ultraviolet ray curable resin (polymerizable compound) is preferable.

As the ultraviolet ray curable resin (polymerizable compound), a resin in which an addition polymerization or a ring-opening polymerization is initiated by radical species or cationic species generated from a photopolymerization initiator by irradiation of ultraviolet rays and by this, a polymer is generated preferably used. As the polymerization mode of addition polymerization, a radical, a cationic, an anionic, a metathesis, and a coordination polymerization can be exemplified. In addition, as the polymerization mode of ring-opening polymerization, a cationic, an anionic, a radical, a metathesis, and a coordination polymerization can be exemplified.

Examples of the addition polymerizable compound include compounds having at least one ethylenically unsaturated double bond. As the addition polymerizable compound, a compound having at least one terminal ethylenically unsaturated bond, and preferably two or more terminal ethylenically unsaturated bonds can be preferably used.

The ethylenically unsaturated polymerizable compound has a monofunctional polymerizable compound, a polyfunctional polymerizable compound, or a chemical form of mixture of these.

Examples of the monofunctional polymerizable compound include an unsaturated carboxylic acid (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid), esters thereof, and amides.

As the polyfunctional polymerizable compound, esters of an unsaturated carboxylic acid and an aliphatic polyol compound, or an amides of an unsaturated carboxylic acid and an aliphatic amine compound are used.

In addition, a product of an addition reaction between unsaturated carboxylic acid esters or amides, which have a nucleophilic substituent such as a hydroxyl group, an amino group, or a mercapto group, and isocyanates or epoxies, a product of a dehydration condensation reaction between the above unsaturated carboxylic acid esters or amides and carboxylic acids, and the like also can be used. Moreover, a product of an addition reaction between unsaturated carboxylic acid esters or amides, which have an electrophilic substituent such as an isocyanate group or an epoxy group, and alcohols, amines, and thiols, and a product of a substitution reaction between unsaturated carboxylic acid esters or amides, which have a leaving substituent such as a halogen group or a tosyloxy group, and alcohols, amines, or thiols also can be used.

As specific example of the radical polymerizable compound which is an ester of an unsaturated carboxylic acid and an aliphatic polyol compound, (meth)acrylic acid ester is representatively exemplified, and any of a monofunctional compound and a polyfunctional compound can be used.

Specific examples of a monofunctinoal (meth)acrylate include tolyoxyethyl (meth)acrylate, phenyloxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, isobornyl (meth)acrylate, dipropylene glycol di(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

Specific examples of a bifunctional (meth)acrylate include ethylene glycol di(meth)acrylate, triethylene glycol di (meth) acrylate, 1,3-butanediol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, and dipentaerythritol di(meth)acrylate.

Specific examples of a trifunctional (meth)acrylate include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, alkylene oxide-modified tri(meth)acrylate of trimethylolpropane, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylolpropane tri((meth)acryloyloxypropyl)ether, isocyanuric acid alkylene oxide-modified tri(meth)acrylate, propionic acid dipentaerythritol tri(meth)acrylate, tri((meth)acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylol propane tri(meth)acrylate, and sorbitol tri(meth)acrylate.

Specific examples of a tetrafunctional (meth)acrylate include pentaerythritol tetra(meth)acrylate, sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, propionic acid dipentaerythritol tetra(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate.

Specific examples of a pentafunctional (meth)acrylate include sorbitol penta(meth)acrylate and dipentaerythritol penta(meth)acrylate.

Specific examples of a hexafunctional (meth)acrylate include dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate of phosphazene, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

Examples of polymerizable compounds other than (meth)acrylates include itaconic acid ester, crotonic acid ester, isocrotonic acid ester, and maleic acid ester.

Examples of the itaconic acid ester include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, and sorbitol tetraitaconate.

Examples of the crotonic acid ester include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.

Examples of the isocrotonic acid ester include ethylene glycol diisocrotonate, pentaerythritol isocrotonate, and sorbitol tetraisocrotonate.

Examples of the maleic acid ester include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

As examples of other esters, for example, aliphatic alcohol-based esters described in JP-B-46-27926, JP-B-51-47334, and JP-A-57-196231, esters having an aromatic structure described in JP-A-59-5240, JP-A-59-5241, and JP-A-2-226149, and esters containing an amino group described in JP-A-1-165613 can also be used.

In addition, specific examples of the amide monomer of an unsaturated carboxylic acid and an aliphatic amine compound include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene-bis-acrylamide, 1,6-hexamethylene-bis-methacrylamide, diethylenetriamine trisacrylamide, xylylene bis-acrylamide, xylylene bis-methacrylamide, and (meth)acryloyl morpholine.

As other preferred amide-based monomers, an amide-based monomer having a cyclohexylene structure described in JP-B-54-21726 can be exemplified.

In addition, a urethane-based addition polymerizable compound manufactured by an addition reaction between isocyanate and a hydroxy group is also suitable, and as the specific example, a vinyl urethane compound containing two or more polymerizable vinyl groups in a molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (1) to a polyisocyanate compound having two or more isocyanate groups in a molecule described in JP-B-48-41708 can be exemplified.
CH₂=C(R¹)COOCH₂CH(R²⁾OH (1) (here, in the formula (1), each of R¹ and R² independently represents H or CH₃.)

In the invention, a cationic ring-opening polymerizable compound having one or more cyclic ether groups such as an epoxy group or an oxetane group in a molecule can be suitably used as an ultraviolet ray curable resin (polymerizable compound).

As the cationic polymerizable compound, curable compounds including a ring-opening polymerizable group can be exemplified, and among these, a heterocyclic group-containing curable compound is particularly preferable. Examples of such curable compounds include cyclic imino ethers such as epoxy derivatives, oxetane derivatives, tetrahydrofuran derivatives, cyclic lactone derivatives, cyclic carbonate derivatives, and oxazoline derivatives, and vinyl ethers, and among these, epoxy derivatives, oxetane derivatives and vinyl ethers are preferable.

Examples of the preferred epoxy derivatives include monofunctional glycidyl ethers, polyfunctional glycidyl ethers, monofunctional alicyclic epoxy, and polyfunctional alicyclic epoxy.

Examples of the specific compounds of glycidyl ethers include diglycidyl ethers (for example, ethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, and the like), tri- or higher functional glycidyl ethers (for example, trimethylol ethane triglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, triglycidyl trishydroxyethyl isocyanurate, and the like), tetra or higher functional glycidyl ethers (for example, sorbitol tetraglycidyl ether, pentaerythritol tetraglycyl ether, polyglycidyl ether of a cresol novolac resin, polyglycidyl ether of a phenolic novolac resin, and the like), alicyclic epoxies (for example, Celloxide 2021P, Celloxide 2081, Epolead GT-301, Epolead GT-401 (manufactured by Daicel Chemical Industries, Ltd.)), EHPE (manufactured by Daicel Chemical Industries, Ltd.), polycyclohexyl epoxymethyl ether of a phenolic novolac resin, and the like), and oxetanes (for example, OX-SQ, PNOX-1009 (hereinbefore, manufactured by Toagosei Co., Ltd.), and the like).

As the polymerizable compound, alicyclic epoxy derivatives can be preferably used. "Alicyclic epoxy group" refers to a substructure obtained by epoxidizing the double bond in the cycloalkene ring of a cyclopentene group, a cyclohexene group, or the like with a suitable oxidant such as hydrogen peroxide, peroxy acid, or the like.

As the alicyclic epoxy compound, polyfunctional alicyclic epoxy compounds having two or more cyclohexene oxide groups or cyclopentene oxide groups in a molecule is preferable. Specific examples of the alicyclic epoxy compound include 4-vinylcyclohexene dioxide, (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexyl carboxylate, di(3,4-epoxycyclohexyl)adipate, di(3,4-epoxycyclohexylmethyl)adipate, bis(2,3-epoxycyclopentyl)ether, di(2,3-epoxy-6-methylcyclohexylmethyl)adipate, and dicyclopentadiene dioxide.

A glycidyl compound having an ordinary epoxy group which does not have an alicyclic structure in the molecule may be used alone or in combination with the above alicyclic epoxy compounds.

As such an ordinary glycidyl compound, a glycidyl ether compound and a glycidyl ester compound can be exemplified, and the glycidyl ether compound is preferably used in combination.

Specific examples of the glycidyl ether compound include aromatic glycidyl ether compounds such as 1,3-bis(2,3-epoxypropyloxy)benzene, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol-novolac type epoxy resin, a cresol-novolac type epoxy resin, and a trisphenolmethane type epoxy resin, and aliphatic glycidyl ether compounds such as 1,4-butanediol glycidyl ether, glycerol triglycidyl ether, propylene glycol diglycidyl ether, and trimethylolpropane tritriglycidyl ether. As the glycidyl ester, a glycidyl ester of a linolenic acid dimer and the like can be exemplified.

As the polymerizable compound, a compound (hereinafter, simply referred to as "oxetane compound") having an oxetanyl group which is a cyclic ether having a four-membered ring can be used. An oxetanyl group-containing compound is a compound having one or more oxetanyl groups in a molecule.

The ink for forming an outermost layer 4A, among the curing components described above, in particular, preferably includes one type or two or more types selected from the group consisting of 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, polyether-based aliphatic urethane (meth)acrylate oligomer, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Thereby, it is possible to cure the ink for forming an outermost layer 4A at a more suitable curing rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, it is possible to make the mechanical strength and stability of the shape of the outermost layer 7 formed by curing the ink for forming an outermost layer 4A excellent. As a result, it is possible to make strength, durability, reliability of the three-dimensional structure 1 excellent.

In addition, by including these curing components, it is possible to make a solubility and a swelling property of a cured product of the ink for forming an outermost layer 4A with respect to various solvents (for example, water and the like) particularly low. As a result, it is possible to more reliably remove the sacrificial layer 8 with high selectivity in the sacrificial layer removing step, and it is also possible to prevent unintended deformation due to occurrence of defects in the outermost layer 7. As a result, it is possible to more reliably further increase the dimensional accuracy of the three-dimensional structure 1.

In addition, since it is possible to make a swelling property (absorbability of a solvent) of a cured product of the ink for forming an outermost layer 4A low, for example, it is possible to omit or simplify a drying treatment as a post-treatment after the sacrificial layer removing step. In addition, since solvent resistance of the finally obtained three-dimensional structure 1 can also be improved, reliability of the three-dimensional structure 1 is particularly high.

In particular, when the ink for forming an outermost layer 4A includes 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, since oxygen inhibition is less likely occur, curing at low energy is possible, and effects in which copolymerization including other monomers is promoted, and the strength of a formed object is increased are obtained.

In addition, when the ink for forming an outermost layer 4A includes a polyether-based aliphatic urethane (meth)acrylate oligomer, an effect in which both high strength and high toughness of a formed object are achieved is obtained.

In addition, when the ink for forming an outermost layer 4A includes 2-hydroxy-3-phenoxypropyl (meth)acrylate, an effect which has flexibility and in which a breaking elongation is improved is obtained.

In addition, when the ink for forming an outermost layer 4A includes 4-hydroxybutyl (meth)acrylate, an effect in which strength of a formed object is increased is obtained by improving adhesion to PMMA particles, PEMA particles, silica particles, or metal particles.

In a case where the ink for forming an outermost layer 4A includes a specific curing component described above (one type or two or more types selected from the group consisting of 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, polyether-based aliphatic urethane (meth)acrylate oligomer, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate), the proportion of the specific curing component with respect to the entire curing components configuring the ink for forming an outermost layer 4A is preferably equal to or greater than 80% by mass, more preferably equal to or greater than 90% by mass, and still more preferably 100% by mass. Thereby, effects as described above are more significantly exhibited.

The content of the curing component in the ink for forming an outermost layer 4A is preferably 80% by mass to 97% by mass, and more preferably 85% by mass to 95% by mass.

Thereby, it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent. In addition, it is possible to make productivity of the three-dimensional structure 1 excellent.

(Polymerization Initiator 1)
In addition, the ink for forming an outermost layer 4A preferably includes a polymerization initiator.

Thereby, it is possible to increase the curing rate of the ink for forming an outermost layer 4A when the three-dimensional structure 1 is manufactured, and it is possible to make productivity of the three-dimensional structure 1 excellent.

As the polymerization initiator, for example, a photo-radical polymerization initiator (aromatic ketones, an acyl phosphine oxide compound, an aromatic onium salt compound, an organic peroxide, a thio compound (a thioxanthone compound, a thiophenyl group-containing compound, and the like), a hexaaryl biimidazole compound, a ketooxime ester compound, a borate compound, an azinium compound, a metallocene compound, an active ester compound, a compound having a carbon-halogen bond, an alkyl amine compound, and the like), or a photo-cationic polymerization initiator can be used, and specific examples thereof include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methyl acetophenone, 4-chloro-benzophenone, 4,4'-dimethoxy benzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropyl thioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4-(methylthio)phenyl]-2-morpholino-propan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethyl pentyl phosphine oxide. One type or two or more types selected from these can be used singly or in combination.

Among these, a polymerization initiator configuring the ink for forming an outermost layer 4A preferably includes bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide or 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

Thereby, by including such a polymerization initiator, it is possible to cure the ink for forming an outermost layer 4A at a more suitable curing rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, it is possible to make the mechanical strength and stability of the shape of the outermost layer 7 formed by curing the ink for forming an outermost layer 4A excellent. As a result, it is possible to make strength, durability, and reliability of the three-dimensional structure 1 excellent.

In particular, when the ink for forming an outermost layer 4A, together with the ink for forming a sacrificial layer 4B described below in detail, includes bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as a polymerization initiator, it is possible to more suitably control the curing rate with respect to the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B. As a result, it is possible to make productivity of the three-dimensional structure 1 excellent.

When the ink for forming an outermost layer 4A, together with the ink for forming a sacrificial layer 4B described below in detail, includes bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as a polymerization initiator, the content of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide in the ink for forming an outermost layer 4A is preferably higher than the content of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide in the ink for forming a sacrificial layer 4B.

Thereby, it is possible to cure each of the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B at a more suitable rate.

The content of a polymerization initiator in the ink for forming an outermost layer 4A is not particularly limited, however, is preferably higher than the content of a polymerization initiator in the ink for forming a sacrificial layer 4B.

In addition, for example, by adjusting the treatment conditions in the curing step, after the curing step ends, it is possible to make a polymerization degree of the sacrificial layer 8 relatively low while sufficiently increasing a degree of cure of the outermost layer 7. As a result, it is possible to more easily remove the sacrificial layer 8 in the sacrificial layer removing step, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, since there is no need to necessarily increase the amount of energy ray to be irradiated, this is preferable from the viewpoint of saving energy.

In particular, when the content of the polymerization initiator in the ink for forming an outermost layer 4A is defined as X₁ [% by mass], and the content of the polymerization initiator in the ink for forming a sacrificial layer 4B is defined as X₂ [% by mass], the relationship of 1.05 smaller than or equal to X₁/X₂ smaller than or equal to 2.0 is preferably satisfied, and the relationship of 1.1 smaller than or equal to X₁/X₂ smaller than or equal to 1.5 is preferably satisfied.

Thereby, it is possible to cure each of the ink for forming an outermost layer 4A and the ink for forming a sacrificial layer 4B at a more suitable rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

The specific value of the content of the polymerization initiator in the ink for forming an outermost layer 4A is preferably 3.0% by mass to 18% by mass, and more preferably 5.0% by mass to 15% by mass.

Thereby, it is possible to cure the ink for forming an outermost layer 4A at a more suitable curing rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

A preferred specific example of the mixing ratio (ink constitution except for "other components" described below) of a curable resin and a polymerization initiator in the ink for forming an outermost layer 4A is shown below, however, needless to say, the constitution of the ink for forming an outermost layer in the invention is not limited to that described below.
(Mixing Ratio Example)
2-(2-vinyloxyethoxy)ethyl acrylate: 32 parts by mass
Polyether-based aliphatic urethane acrylate oligomer: 10 parts by mass
2-Hydroxy-3-phenoxypropylacrylate: 13.75 parts by mass
Dipropylene glycol diacrylate: 15 parts by mass
4-Hydroxybutylacrylate: 20 parts by mass
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: 5 parts by mass
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide: 4 parts by mass

In a case of mixing as described above, effects as described above are more significantly exhibited.

(Other Components 1)
In addition, the ink for forming an outermost layer 4A may include components other than the components described above.

Examples of such components include various colorants such as a pigment and a dye; a dispersant; a surfactant; a sensitizer; a polymerization accelerator; a solvent; a penetration enhancer; a wetting agent (humectant); a fixing agent; a fungicide; a preservative; an antioxidant; an ultraviolet absorbent; a chelating agent; a pH adjusting agent; a thickener; a filler; an aggregation preventing agent; and a defoamer.

In particular, when the ink for forming an outermost layer 4A includes a colorant, it is possible to obtain the three-dimensional structure 1 which is colored in the color corresponding to the color of the colorant.

In particular, by including a pigment as a colorant, it is possible to make the light resistance of the ink for forming an outermost layer 4A and the three-dimensional structure 1 more favorable. Both an inorganic pigment and an organic pigment can be used as the pigment.

Examples of the inorganic pigment include carbon blacks (C.I. Pigment Black 7) such as a furnace black, a lamp black, an acetylene black, and a channel black, iron oxide, and titanium oxide, and one type or two or more types selected from these can be used singly or in combination.

Among the inorganic pigments, titanium oxide is preferable in order to exhibit a preferred white color.

Examples of the organic pigments include azo pigments such as an insoluble azo pigment, a condensed azo pigment, an azo lake, and a chelate azo pigment, polycyclic pigments such as a phthalocyanine pigment, a perylene, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxane pigment, a thioindigo pigment, an isoindolinone pigment, and a quinophthalone pigment, a dye chelate (for example, a base dye type chelate, an acid dye type chelate, and the like), a dyeing lake (a basic dye type lake and an acidic dye type lake), a nitro pigment, a nitroso pigment, an aniline black, and a daylight fluorescent pigment, and one type or two or more types selected from these can be used singly or in combination.

More specifically, examples of the carbon black used as a black pigment include No. 2300, No. 900, MCF 88, No. 33, No. 40, No. 45, No. 52, MA 7, MA 8, MA 100, No. 2200B, and the like (hereinbefore, manufactured by Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, and the like (hereinbefore, manufactured by Carbon Columbia, Ltd.), Regal 400R, Regal 330R, Regal 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, and the like (hereinbefore, manufactured by CABOT JAPAN K.K.), and Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and Special Black 4 (hereinbefore, manufactured by Degussa).

Examples of the white pigment include C.I.

Pigment White

6, 18 and 21.

Examples of the yellow pigment include C.I.

Pigment Yellow

1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, and 180.

Examples of the magenta pigment include C.I.

Pigment Red

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, and 245, or C.I.

Pigment Violet

19, 23, 32, 33, 36, 38, 43, and 50.

Examples of the cyan pigment include C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, and 66, and C.I. Vat Blue 4 and 60.

In addition, examples of the pigments other than the pigments described above include C.I. Pigment Green 7, 10, C.I. Pigment Brown 3, 5, 25, 26, and C.I.

Pigment Orange

1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43 and 63.

In a case where the ink for forming an outermost layer 4A includes a pigment, the average particle size of the pigment is preferably equal to or less than 300 nm, and more preferably 50 nm to 250 nm.

Thereby, it is possible to be make the discharge stability of the ink for forming an outermost layer 4A and the dispersion stability of the pigment in the ink for forming an outermost layer 4A excellent, and it is possible to form an image having excellent image quality.

In addition, examples of the dyes include an acid dye, a direct dye, a reactive dye, and a basic dye, and one type or two or more types selected from these can be used singly or in combination.

Specific examples of the dye include C.I.

Acid Yellow

17, 23, 42, 44, 79, and 142, C.I. Acid Red 52, 80, 82, 249, 254, and 289, C.I. Acid Blue 9, 45, and 249, C.I.

Acid Black

1, 2, 24, and 94, C.I. Food Black 1 and 2, C.I.

Direct Yellow

1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, and 173, C.I.

Direct Red

1, 4, 9, 80, 81, 225, and 227, C.I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, and 202, C.I. Direct Black 19, 38, 51, 71, 154, 168, 171 and 195, C.I. Reactive Red 14, 32, 55, 79, and 249, and C.I. Reactive Black 3, 4, and 35.

In a case where the ink for forming an outermost layer 4A includes a colorant, the content of the colorant in the ink for forming an outermost layer 4A is preferably 1% by mass to 20% by mass. Thereby, an excellent concealing property and color reproducibility are obtained.

In particular, in a case where the ink for forming an outermost layer 4A includes titanium oxide as a colorant, the content of the titanium oxide in the ink for forming an outermost layer 4A is preferably 12% by mass to 18% by mass, and more preferably 14% by mass to 16% by mass. Thereby, an excellent concealing property is obtained.

In a case where the ink for forming an outermost layer 4A includes a pigment, if the ink for forming an outermost layer 4A further includes a dispersant, it is possible to make the dispersibility of the pigment more favorable.

Examples of the dispersant, which are not particularly limited, include dispersants which are commonly used in the preparation of pigment dispersions such as a polymer dispersant.

Specific examples of the polymer dispersant include dispersants containing one or more types among polyoxyalkylene polyalkylene polyamine, a vinyl-based polymer and copolymer, an acrylic polymer and copolymer, polyester, polyamide, polyimide, polyurethane, an amino-based polymer, a silicon-containing polymer, a sulfur-containing polymer, a fluorine-containing polymer, and an epoxy resin, as a main component.

Examples of commercially available polymer dispersants include Ajisper series manufactured by Ajinomoto Fine-Techno Co., Inc., Solsperse series (Solsperse 36000 and the like) available from Noveon Inc., and Disperbyk series manufactured by BYK Chemie, and Disparlon series manufactured by Kusumoto Chemicals, Ltd.

If the ink for forming an outermost layer 4A includes a surfactant, it is possible to make the abrasion resistance of the three-dimensional structure 1 more favorable.

The surfactant is not particularly limited, and for example, silicone-based surfactants such as polyester-modified silicone or polyether-modified silicone can be used, and among these, polyether-modified polydimethyl siloxane or polyester-modified polydimethyl siloxane is preferably used.

Specific examples of the surfactant include BYK-347, BYK-348, BYK-UV3500, 3510, 3530, and 3570 (product names, manufactured by BYK Co., Ltd.).

In addition, the ink for forming an outermost layer 4A may include a solvent.

Thereby, it is possible to suitably adjust the viscosity of the ink for forming an outermost layer 4A, and even in a case where the ink for forming an outermost layer 4A includes a component having a high viscosity, it is possible to make the discharge stability of the ink for forming an outermost layer 4A by an ink jet method excellent.

Examples of the solvent include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; acetic acid esters such as ethyl acetate, N-propyl acetate, iso-propyl acetate, N-butyl acetate, and iso-butyl acetate; aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl-n-butyl ketone, diisopropyl ketone, and acetyl acetone; and alcohols such as ethanol, propanol, and butanol, and one type or two or more types selected from these can be used singly or in combination.

In addition, the viscosity of the ink for forming an outermost layer 4A is preferably 10 mPa*s to 30 mPa*s, and more preferably 15 mPa*s to 25 mPa*s.

Thereby, it is possible to make the discharge stability of the ink for forming an outermost layer 4A by an ink jet method excellent. Moreover, in the present specification, the viscosity refers to a value measured at 25 degrees centigrade by using an E type viscometer (VISCONIC ELD manufactured by Tokyo Keiki Inc.).

In addition, in manufacturing the three-dimensional structure 1, plural types of the ink for forming an outermost layer 4A may be used.

For example, an ink (color ink) for forming an outermost layer 4A including a colorant and an ink (clear ink) for forming an outermost layer 4A not including a colorant may be used.

Thereby, for example, regarding an appearance of the three-dimensional structure 1, it is possible to use the ink for forming an outermost layer 4A including a colorant as the ink for forming an outermost layer 4A applied to a region that affects the color, and regarding an appearance of the three-dimensional structure 1, it is possible to use the ink for forming an outermost layer 4A not including a colorant as the ink for forming an outermost layer 4A applied to a region that does not affect the color, and thus, it is advantageous from the viewpoint of reduction in the production cost of the three-dimensional structure 1.

In addition, in the finally obtained three-dimensional structure 1, plural types of the ink for forming an outermost layer 4A may be used in combination such that a region (coating layer) formed by using the ink for forming an outermost layer 4A not including a colorant is provided to the outer surface of a region formed by using the ink for forming an outermost layer 4A including a colorant.

In addition, for example, plural types of the ink for forming an outermost layer 4A including colorants having different constitutions may be used.

Thereby, by combination of these inks for forming an outermost layer A4, it is possible to widen a color reproduction region that can be expressed.

In a case of using plural types of the ink for forming an outermost layer 4A, it is preferable to use at least an ink for forming an outermost layer 4A having a cyan color, an ink for forming an outermost layer 4A having a magenta color, and an ink for forming an outermost layer 4A having a yellow color.

Thereby, by combination of these inks for forming an outermost layer A4, it is possible to further widen a color reproduction region that can be expressed.

In addition, by using the ink for forming an outermost layer 4A having a white color and other inks for forming an outermost layer 4A having another color in combination, for example, the following effect is obtained.

That is, it is possible to make the finally obtained three-dimensional structure 1 have a first region where the ink for forming an outermost layer 4A having a white color is applied and a region (second region) where the ink for forming an outermost layer 4A having a color other than a white color provided on the outer surface than the first region is applied. Thereby, the first region where the ink for forming an outermost layer 4A having a white color is applied can exhibit a concealing property, and it is possible to further increase color saturation of the three-dimensional structure 1.

In addition, an effect in which fine texture as described above is obtained and an effect in which color saturation is increased act synergistically, and thus, it is possible to make the aesthetic appearance (aesthetics) of the three-dimensional structure 1 excellent.

Moreover, as the binding ink 4C, a clear ink not including a colorant may be used, and a white ink may be used.

(Ink for Forming Sacrificial Layer)
The ink for forming a sacrificial layer 4B includes at least a curable resin (curing component).

(Curable Resin 2)
As the curable resin (curing component) configuring the ink for forming a sacrificial layer 4B, the same resin as the curable resin (curing component) exemplified as a constituent of the ink for forming an outermost layer 4A can be exemplified.

In particular, the curable resin (curing component) configuring the ink for forming a sacrificial layer 4B and the curable resin (curing component) configuring the ink for forming an outermost layer 4A described above are preferably cured by the same energy rays.

Thereby, it is possible to effectively prevent the configuration of the three-dimensional structure manufacturing apparatus from being complicated, and it is possible to make productivity of the three-dimensional structure 1 excellent. In addition, it is possible to more reliably control the surface shape of the three-dimensional structure 1.

Among various curing components, the ink 4B for forming a sacrificial layer, in particular, preferably includes one type or two or more types selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, polyethyleneglycol di(meth)acrylate, (meth)acryloyl morpholine, and 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.

Thereby, it is possible to cure the ink for forming a sacrificial layer 4B at a more suitable curing rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, it is possible to make the mechanical strength and stability of the shape of the sacrificial layer 8 formed by curing the ink for forming a sacrificial layer 4B excellent. As a result, when the three-dimensional structure 1 is produced, the sacrificial layer 8 which is the lower layer (first layer) can more suitably support the ink for forming an outermost layer 4A for forming the upper layer (second layer). For this reason, it is possible to more suitably prevent unintended deformation (in particular, sagging or the like) of the outermost layer 7 (the sacrificial layer 8 which is the first layer functions as a support material), and it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent.

In particular, in a case where the ink for forming a sacrificial layer 4B includes (meth)acryloyl morpholine, the following effects are obtained.

That is, in a state of being not completely cured even in a case where the curing reaction proceeds (polymer of (meth)acryloyl morpholine in a state of being not completely cured), there are many cases that (meth)acryloyl morpholine has a high solubility with respect to various solvents such as water. Therefore, in the sacrificial layer removing step as described above, it is possible to selectively, reliably, and efficiently remove the sacrificial layer 8 while more effectively preventing occurrence of defects in the outermost layer 7. As a result, it is possible to obtain the three-dimensional structure 1 having the desired form with high productivity and higher reliability.

In addition, in a case where the ink for forming a sacrificial layer 4B includes tetrahydrofurfuryl (meth)acrylate, an effect in which flexibility after curing is maintained, and removability is increased due to a gel state readily being brought about by a treatment with a liquid for removing the sacrificial layer 8 is obtained.

In addition, in a case where the ink for forming a sacrificial layer 4B includes ethoxyethoxyethyl (meth)acrylate, an effect in which tackiness is likely to remain even after curing, and removability by a liquid for removing the sacrificial layer 8 is increased is obtained.

In addition, in a case where the ink for forming a sacrificial layer 4B includes polyethylene glycol di(meth)acrylate, when a liquid for removing the sacrificial layer 8 has water as a main component, an effect in which solubility in the liquid water is increased, and thus, removal becomes easy is obtained.

In a case where the ink for forming a sacrificial layer 4B includes a specific curing component described above (one type or two or more types selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, polyethylene glycol di(meth)acrylate, and (meth)acryloyl morpholine), the proportion of the specific curing component with respect to the entire curing components configuring the ink for forming a sacrificial layer 4B is preferably equal to or greater than 80% by mass, more preferably equal to or greater than 90% by mass, and still more preferably 100% by mass. Thereby, effects as described above are more significantly exhibited.

The content of the curing component in the ink 4B for forming a sacrificial layer is preferably 83% by mass to 98.5% by mass, and more preferably 87% by mass to 95.4% by mass.

Thereby, it is possible to make stability of the shape of the sacrificial layer 8 formed excellent, and in a case where the unit layers are superposed when the three-dimensional structure 1 is manufactured, it is possible to more effectively prevent the lower side unit layer from being unintentionally deformed, and it is possible to suitably support the upper side unit layer. As a result, it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent. In addition, it is possible to make productivity of the three-dimensional structure 1 excellent.

(Polymerization Initiator 2)
In addition, the ink for forming a sacrificial layer 4B preferably includes a polymerization initiator.

Thereby, it is possible to suitably increase the curing rate of the ink for forming a sacrificial layer 4B when the three-dimensional structure 1 is manufactured, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, it is possible to make stability of the shape of the sacrificial layer 8 formed excellent, and in a case of the unit layers being superposed when the three-dimensional structure 1 is manufactured, it is possible to more effectively prevent the lower side unit layer from being unintentionally deformed, and it is possible to suitably support the upper side unit layer. As a result, it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent.

As the polymerization initiator configuring the ink for forming a sacrificial layer 4B, the same polymerization initiator as the polymerization initiator exemplified as a constituent of the ink for forming an outermost layer 4A can be exemplified.

Among these, the ink for forming a sacrificial layer 4B preferably includes bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, or 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a polymerization initiator.

Thereby, by including such a polymerization initiator, it is possible to cure the ink for forming a sacrificial layer 4B at a more suitable curing rate, and it is possible to make productivity of the three-dimensional structure 1 excellent.

In addition, it is possible to make the mechanical strength and stability of the shape of the sacrificial layer 8 formed by curing the ink for forming a sacrificial layer 4B excellent. As a result, when the three-dimensional structure 1 is manufactured, the sacrificial layer 8 which is the lower layer (first layer) can more suitably support the ink for forming an outermost layer 4A for forming the upper layer (second layer). For this reason, it is possible to more suitably prevent unintended deformation (in particular, sagging or the like) of the outermost layer 7 (the sacrificial layer 8 which is the first layer functions as a support material), and it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent.

The specific value of the content of the polymerization initiator in the ink for forming a sacrificial layer 4B is preferably 1.5% by mass to 17% by mass, and more preferably 4.6% by mass to 13% by mass.

A preferred specific example of the mixing ratio (ink constitution except for "other components" described below) of a curable resin and a polymerization initiator in the ink for forming a sacrificial layer 4B is shown below, however, needless to say, the constitution of the ink for forming a sacrificial layer in the invention is not limited to that described below.
(Mixing Ratio Example 1)
Tetrahydrofurfurylacrylate: 36 parts by mass
Ethoxyethoxyethylacrylate: 55.75 parts by mass
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: 3 parts by mass
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide: 5 parts by mass
(Mixing Ratio Example 2)
Dipropylene glycol diacrylate: 37 parts by mass
Polyethylene glycol (400) diacrylate: 55.85 parts by mass
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: 3 parts by mass
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide: 4 parts by mass
(Mixing Ratio Example 3)
Tetrahydrofurfurylacrylate: 36 parts by mass
Acryloyl morpholine: 55.75 parts by mass
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: 3 parts by mass
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide: 5 parts by mass
(Mixing Ratio Example 4)
Acrylic acid 2-(2-vinyloxyethoxy)ethyl: 36 parts by mass
Polyethylene glycol (400) diacrylate: 55.75 parts by mass
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: 3 parts by mass
2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide: 5 parts by mass

(Other Components 2)
In addition, the ink for forming a sacrificial layer 4B may include components other than the components described above. Examples of such components include various colorants such as a pigment and a dye; a dispersant; a surfactant; a sensitizer; a polymerization accelerator; a solvent; a penetration enhancer; a wetting agent (humectant); a fixing agent; a fungicide; a preservative; an antioxidant; an ultraviolet absorbent; a chelating agent; a pH adjusting agent; a thickener; a filler; an aggregation preventing agent; and a defoamer.

In particular, when the ink for forming a sacrificial layer 4B includes a colorant, the visibility of the sacrificial layer 8 is improved, and in the finally obtained three-dimensional structure 1, it is possible to more reliably prevent at least a part of the sacrificial layer 8 from unintentionally remaining.

As the colorant configuring the ink for forming a sacrificial layer 4B, the same colorant as the colorant exemplified as a constituent of the ink for forming an outermost layer 4A can be exemplified, and the colorant is preferably a colorant which becomes a color different from the color (color to be seen in the appearance of the three-dimensional structure 1) of the outermost layer 7 overlapped with the sacrificial layer 8 formed by the ink for forming a sacrificial layer 4B when observed from the normal direction of the surface of the three-dimensional structure 1. Thereby, effects as described above are more significantly exhibited.

In a case where the ink for forming a sacrificial layer 4B includes a pigment, if the ink for forming an outermost layer 4A further includes a dispersant, it is possible to make the dispersibility of the pigment more favorable. As the dispersant configuring the ink for forming a sacrificial layer 4B, the same dispersant as the dispersant exemplified as a constituent of the ink for forming an outermost layer 4A can be exemplified.

In addition, the viscosity of the ink for forming a sacrificial layer 4B is preferably 10 mPa*s to 30 mPa*s, and more preferably 15 mPa*s to 25 mPa*s.

Thereby, it is possible to make the discharge stability of the ink for forming a sacrificial layer 4B by an ink jet method excellent.

Moreover, the ink set may be an ink set which is equipped with at least one of the ink for forming an outermost layer 4A, at least one of the ink for forming a sacrificial layer 4B, and the binding ink 4C, and may be equipped with a fourth ink different from these inks.

(4. Composition for Forming a Three-dimensional Object)
Next, the composition for forming a three-dimensional object will be described in detail.

The composition for forming a three-dimensional object includes the powder for forming a three-dimensional object and the water-soluble resin 64.

Hereinafter, each component will be described in detail.

(Powder for Forming Three-dimensional Object)
The powder for forming a three-dimensional object is configured of a plurality of particles 63.

As the particles 63, any particles can be used, and the particles 63 are preferably configured of porous particles. Thereby, when the three-dimensional structure 1 is manufactured, the curable resin 44 included in the binding ink 4C can suitably penetrate into pores, and as a result, porous particles can be suitably used for manufacturing a three-dimensional structure having excellent mechanical strength.

Examples of the constituent material of the porous particles configuring the powder for forming a three-dimensional object include an inorganic material, an organic material, and a complex of these.

Examples of the inorganic material configuring the porous particles include various metals, a metal compound, and the like. Examples of the metal compound include various metal oxides such as silica, alumina, titanium oxide, zinc oxide, zirconium oxide, tin oxide, magnesium oxide, and potassium titanate; various metal hydroxides such as magnesium hydroxide, aluminum hydroxide, and calcium hydroxide; various metal nitrides such as silicon nitride, titanium nitride, and aluminum nitride; various metal carbides such as silicon carbide and titanium carbide; various metal sulfides such as zinc sulfide; various metal carbonates such as calcium carbonate and magnesium carbonate; various metal sulfates such as calcium sulfate and magnesium sulfate; various metal silicates such as calcium silicate and magnesium silicate; various metal phosphates such as calcium phosphate; and various metal borates such as aluminum borate and magnesium borate, or composite compounds of these.

As the organic material configuring the porous particles, synthetic resins and natural polymers can be exemplified, and more specific examples include a polyethylene resin; polypropylene; polyethylene oxide; polypropylene oxide, polyethylene imine; polystyrene; polyurethane; polyurea; polyester; a silicone resin; an acrylic silicone resin; polymers having (meth)acrylic acid ester as a constituent monomer such as polymethyl methacrylate; cross polymers having (meth)acrylic acid ester as a constituent monomer such as methyl methacrylate cross polymer (ethylene acrylic acid copolymer resin or the like); polyamide resins such as Nylon 12, Nylon 6, and copolymer nylon; polyimide; carboxymethyl cellulose; gelatin; starch; chitin; and chitosan.

Among these, the porous particles are preferably configured of an inorganic material, more preferably configured of metal oxide, and still more preferably configured of silica. Thereby, it is possible to make characteristics such as mechanical strength and light resistance of the three-dimensional structure excellent. In addition, in particular, in a case where the porous particles are configured of silica, the effect as described above is more significantly exhibited. In addition, since silica has also excellent fluidity, silica is useful for forming a layer having higher thickness uniformity, and it is possible to make productivity and dimensional accuracy of the three-dimensional structure 1 excellent.

As the silica, commercially available products can be suitably used. Specific examples include Mizukasil P-526, Mizukasil P-801, Mizukasil NP-8, Mizukasil P-802, Mizukasil P-802Y, Mizukasil C-212, Mizukasil P-73, Mizukasil P-78A, Mizukasil P-78F, Mizukasil P-87, Mizukasil P-705, Mizukasil P-707, Mizukasil P-707D, Mizukasil P-709, Mizukasil C-402, and Mizukasil C-484 (manufactured by Mizusawa Industrial Chemicals, Ltd.), Tokusil U, Tokusil UR, Tokusil GU, Tokusil AL-1, Tokusil GU-N, Tokusil N, Tokusil NR, Tokusil PR, SOLEX, Fine Seal E-50, Fine Seal T-32, Fine Seal X-30, Fine Seal X-37, Fine Seal X-37B, Fine Seal X-45, Fine Seal X-60, Fine Seal X-70, Fine seal RX-70, Fine seal A, and Fine seal B (manufactured by Tokuyama Corporation), Sipernat, Carplex FPS-101, Carplex CS-7, Carplex 22S, Carplex 80, Carplex 80D, Carplex XR, and Carplex 67 (manufactured by DSL. Japan Co., Ltd.), Syloid 63, Syloid 65, Syloid 66, Syloid 77, Syloid 74, Syloid 79, Syloid 404, Syloid 620, Syloid 800, Syloid 150, Syloid 244, and Syloid 266 (manufactured by Fuji Silysia Chemical Ltd.), and Nipgel AY-200, Nipgel AY-6A2, Nipgel AZ-200, Nipgel AZ-6A0, Nipgel BY-200, Nipgel BY-200, Nipgel CX-200, Nipgel CY-200, Nipsil E-150J, Nipsil E-220A, and Nipsil E-200A (manufactured by Tosoh Silica Corporation).

In addition, the porous particles are preferably porous particles on which a hydrophobization treatment is performed. Moreover, in general, the curable resin 44 included in the binding ink 4C tends to have hydrophobicity. Therefore, due to the hydrophobization treatment of porous particles, the curable resin 44 can suitably penetrate into pores of the porous particles. As a result, an anchoring effect is more significantly exhibited, and it is possible to make the mechanical strength of the obtained three-dimensional structure 1 excellent. In addition, in a case where the porous particles are porous particles subjected to the hydrophobization treatment, the porous particles can be suitably reused. In more detail, in a case where the porous particles are subjected to the hydrophobization treatment, affinity between a water-soluble resin described below and the porous particles is decreased, and thereby, the water-soluble resin is prevented from entering into the pores. As a result, when the three-dimensional structure 1 is manufactured, it is possible to easily remove impurities by washing porous particles in the region in which an ink is not applied with water or the like, and it is possible to recover in a high purity. For this reason, by mixing the powder for forming a three-dimensional object recovered with a water-soluble resin or the like at a predetermined proportion again, it is possible to obtain a powder for forming a three-dimensional object reliably controlled to a desired constitution.

As the hydrophobization treatment applied to the porous particles configuring the powder for forming a three-dimensional object, any treatment may be used as long as it increases hydrophobicity of the porous particles, and it is preferable to introduce a hydrocarbon group. Thereby, it is possible to further increase hydrophobicity of the particles. In addition, it is possible to easily and reliably further increase uniformity of the degree of the hydrophobic treatment at each portion (including the surface of the inside of a porous) of each particle or the particle surface.

As a compound used in the hydrophobization treatment, a silane compound including a silyl group is preferable. Specific examples of the compound which can be used in the hydrophobization treatment include hexamethyldisilazane, dimethyl dimethoxysilane, diethyl diethoxysilane, 1-propenylmethyl dichlorosilane, propyldimethyl chlorosilane, propylmethyl dichlorosilane, propyl trichlorosilane, propyl triethoxysilane, propyl trimethoxysilane, styrylethyl trimethoxysilane, tetradecyl trichlorosilane, 3-thiocyanatopropyl triethoxysilane, p-tolydimethyl chlorosilane, p-tolymethyl dichlorosilane, p-toly trichlorosilane, p-toly trimethoxysilane, p-toly triethoxysilane, di-n-propyl di-n-propoxysilane, diisopropyl diisopropoxysilane, di-n-butyl di-n-butyroxysilane, di-sec-butyl di-sec-butyroxysilane, di-t-butyl di-t-butyroxysilane, octadecyl trichlorosilane, octadecylmethyl diethoxysilane, octadecyl triethoxysilane, octadecyl trimethoxysilane, octadecyldimethyl chlorosilane, octadecylmethyl dichlorosilane, octadecyl methoxydichlorosilane, 7-octenyldimethyl chlorosilane, 7-octenyl trichlorosilane, 7-octenyl trimethoxysilane, octylmethyl dichlorosilane, octyldimethyl chlorosilane, octyl trichlorosilane, 10-undecenyldimethyl chlorosilane, undecyl trichlorosilane, vinyldimethyl chlorosilane, methyloctadecyl dimethoxysilane, methyldodecyl diethoxysilane, methyloctadecyl dimethoxysilane, methyloctadecyl diethoxysilane, n-octylmethyl dimethoxysilane, n-octylmethyl diethoxysilane, triacontyldimethyl chlorosilane, triacontyl trichlorosilane, methyl trimethoxysilane, methyl triethoxysilane, methyl tri-n-propoxysilane, methyl isopropoxysilane, methyl-n-butyroxysilane, methyl tri-sec-butyroxysilane, methyl tri-t-butyroxysilane, ethyl trimethoxysilane, ethyl triethoxysilane, ethyl tri-n-propoxysilane, ethyl isopropoxysilane, ethyl-n-butyroxysilane, ethyl tri-sec-butyroxysilane, ethyl tri-t-butyroxysilane, n-propyl trimethoxysilane, isobutyl trimethoxysilane, n-hexyl trimethoxysilane, hexadecyl trimethoxysilane, n-octyl trimethoxysilane, n-dodecyl trimethoxysilane, n-octadecyl trimethoxysilane, n-propyl triethoxysilane, isobutyl triethoxysilane, n-hexyl triethoxysilane, hexadecyl triethoxysilane, n-octyl triethoxysilane, n-dodecyl trimethoxysilane, n-octadecyl triethoxysilane, 2-[2-(trichlorosilyl)ethyl]pyridine, 4-[2-(trichlorosilyl)ethyl]pyridine, diphenyl dimethoxysilane, diphenyl diethoxysilane, 1,3-(trichlorosilylmethyl)heptacosane, dibenzyl dimethoxysilane, dibenzyl diethoxysilane, phenyl trimethoxysilane, phenylmethyl dimethoxysilane, phenyldimethyl methoxysilane, phenyl dimethoxysilane, phenyl diethoxysilane, phenylmethyl diethoxysilane, phenyldimethyl ethoxysilane, benzyl triethoxysilane, benzyl trimethoxysilane, benzylmethyl dimethoxysilane, benzyldimethyl methoxysilane, benzyl dimethoxysilane, benzyl diethoxysilane, benzylmethyl diethoxysilane, benzyldimethyl ethoxysilane, benzyl triethoxysilane, dibenzyl dimethoxysilane, dibenzyl diethoxysilane, 3-acetoxypropyl trimethoxysilane, 3-acryloxypropyl trimethoxysilane, allyl trimethoxysilane, allyl triethoxysilane, 4-aminobutyl triethoxysilane, (aminoethylaminomethyl)phenethyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, 6-(aminohexylaminopropyl) trimethoxysilane, p-aminophenyl trimethoxysilane, p-aminophenyl ethoxysilane, m-aminophenyl trimethoxysilane, m-aminophenyl ethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxydisilane, omega-aminoundecyl trimethoxysilane, amyl triethoxysilane, benzooxasipine dimethylester, 5-(bicycloheptenyl) triethoxysilane, bis(2-hydroxyethyl)-3-aminopropyl triethoxysilane, 8-bromooctyl trimethoxysilane, bromophenyl trimethoxysilane, 3-bromopropyl trimethoxysilane, n-butyl trimethoxysilane, 2-chloromethyl triethoxysilane, chloromethylmethyl diethoxysilane, chloromethylmethyl diisopropoxysilane, p-(chloromethyl)phenyl trimethoxysilane, chloromethyl triethoxysilane, chlorophenyl triethoxysilane, 3-chloropropylmethyl dimethoxysilane, 3-chloropropyl triethoxysilane, 3-chloropropyl trimethoxysilane, 2-(4-chlorosulfonylphenyl)ethyl trimethoxysilane, 2-cyanoethyl triethoxysilane, 2-cyanoethyl trimethoxysilane, cyanomethylphenethyl triethoxysilane, 3-cyanopropyl triethoxysilane, 2-(3-cyclohexenyl)ethyl trimethoxysilane, 2-(3-cyclohexenyl)ethyl triethoxysilane, 3-cyclohexenyl trichlorosilane, 2-(3-cyclohexenyl)ethyl trichlorosilane, 2-(3-cyclohexenyl)ethyldimethyl chlorosilane, 2-(3-cyclohexenyl)ethylmethyl dichlorosilane, cyclohexyldimethyl chlorosilane, cyclohexylethyl dimethoxysilane, cyclohexylmethyl dichlorosilane, cyclohexylmethyl dimethoxysilane, (cyclohexylmethyl)trichlorosilane, cyclohexyl trichlorosilane, cyclohexyl trimethoxysilane, cyclooctyl trichlorosilane, (4-cyclooctenyl)trichlorosilane, cyclopentyl trichlorosilane, cyclopentyl trimethoxysilane, 1,1-diethoxy-1-silacyclopenta-3-en, 3-(2,4-dinitrophenylamino)propyl triethoxysilane, (dimethylchlorosilyl)methyl-7,7-dimethylnorpinane, (cyclohexylaminomethyl)methyl diethoxysilane, (3-cyclopentadienylpropyl)triethoxysilane, N,N-diethyl-3-aminopropyl)trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl triethoxysilane, (furfuryloxymethyl)triethoxysilane, 2-hydroxy-4-(3-triethoxypropoxy)diphenyl ketone, 3-(p-methoxyphenyl)propylmethyl dichlorosilane, 3-(p-methoxyphenyl)propyl trichlorosilane, p-(methylphenethyl)methyl dichlorosilane, p-(methylphenethyl)trichlorosilane, p-(methylphenethyl)dimethyl chlorosilane, 3-morpholinopropyl trimethoxysilane, (3-glycidoxypropyl)methyl diethoxysilane, 3-glycidoxypropyl trimethoxysilane, 1,2,3,4,7,7,-hexachloro-6-methyl diethoxysilyl-2-norbornene, 1,2,3,4,7,7,-hexachloro-6-triethoxysilyl-2-norbornene, 3-iodopropyl trimethoxysilane, 3-isocyanatopropyl triethoxysilane, (mercaptomethyl)methyl diethoxysilane, 3-mercaptopropylmethyl dimethoxysilane, 3-mercaptopropyl dimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-methacryloxypropylmethyl diethoxysilane, 3-methacryloxypropyl trimethoxysilane, methyl {2-(3-trimethoxysilylpropylamino)ethylamino}-3-propionate, 7-octenyl trimethoxysilane, R-N-alpha-phenethyl-N'-triethoxysilylpropyl urea, S-N-alpha-phenethyl-N'-triethoxysilylpropyl urea, phenethyl trimethoxysilane, phenethylmethyl dimethoxysilane, phenethyldimethyl methoxysilane, phenethyl dimethoxysilane, phenethyl diethoxysilane, phenethylmethyl diethoxysilane, phenethyldimethyl ethoxysilane, phenethyl triethoxysilane, (3-phenylpropyl)dimethyl chlorosilane, (3-phenylpropyl)methyl dichlorosilane, N-phenylaminopropyl trimethoxysilane, N-(triethoxysilylpropyl)dansylamide, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, 2-(triethoxysilylethyl)-5-(chloroacetoxy)bicycloheptane, (S)-N-triethoxysilylpropyl-O-menthocarbamate, 3-(triethoxysilylpropyl)-p-nitrobenzamide, 3-(triethoxysilyl)propyl succinic anhydride, N-[5-(trimethoxysilyl)-2-aza-1-oxo-pentyl]caprolactam, 2-(trimethoxysilylethyl)pyridine, N-(trimethoxysilylethyl)benzyl-N,N,N-trimethyl ammonium chloride, phenylvinyl diethoxysilane, 3-thiocyanatopropyl triethoxysilane, (tridecafluoro-1,1,2,2,-tetrahydrooctyl)triethoxysilane, N-{3-(triethoxysilyl)propyl}phthalamic acid, (3,3,3-trifluoropropyl)methyl dimethoxydisilane, (3,3,3-trifluoropropyl)trimethoxydisilane, 1-trimethoxysilyl-2-(chloromethyl)phenyl ethane, 2-(trimethoxysilyl)ethylphenylsulfonyl azide, beta-trimethoxysilylethyl-2-pyridine, trimethoxysilylpropyldiethylene triamine, N-(3-trimethoxysilylpropyl)pyrrole, N-trimethoxysilylpropyl-N,N,N-tributyl ammonium bromide, N-trimethoxysilylpropyl-N,N,N-tributyl ammonium chloride, N-trimethoxysilylpropyl-N,N,N-trimethyl ammonium chloride, vinylmethyldiethoxysilane, vinyl triethoxysilane, vinyl trimethoxysilane, vinylmethyl dimethoxysilane, vinyldimethyl methoxysilane, vinyldimethyl ethoxysilane, vinylmethyl dichlorosilane, vinylphenyl dichlorosilane, vinylphenyl diethoxysilane, vinylphenyl dimethyl silane, vinylphenylmethyl chlorosilane, vinyl triphenoxysilane, vinyl tris-t-butoxysilane, adamantylethyl trichlorosilane, allylphenyl trichlorosilane, (aminoethylaminomethyl)phenethyl trimethoxysilane, 3-aminophenoxydimethylvinyl silane, phenyl trichlorosilane, phenyldimethyl chlorosilane, phenylmethyl dichlorosilane, benzyl trichlorosilane, benzyldimethyl chlorosilane, benzylmethyl dichlorosilane, phenethyldiisopropyl chlorosilane, phenethyl trichlorosilane, phenethyldimethyl chlorosilane, phenethylmethyl dichlorosilane, 5-(bicycloheptenyl)trichlorosilane, 5-(bicycloheptenyl)triethoxysilane, 2-(bicycloheptyl)dimethyl chlorosilane, 2-(bicycloheptyl)trichlorosilane, 1,4- bis(trimethoxysilylethyl)benzene, bromophenyl trichlorosilane, 3-phenoxypropyldimethyl chlorosilane, 3-phenoxypropyl trichlorosilane, t-butylphenyl chlorosilane, t-butylphenyl methoxysilane, t-butylphenyl dichlorosilane, p-(t-butyl)phenethyldimethyl chlorosilane, p-(t-butyl)phenethyl trichlorosilane, 1,3-(chlorodimethylsilylmethyl)heptacosane, ((chloromethyl)phenylethyl)dimethyl chlorosilane, ((chloromethyl)phenylethyl)methyl dichlorosilane, ((chloromethyl)phenylethyl)trichlorosilane, ((chloromethyl)phenylethyl)trimethoxysilane, chlorophenyl trichlorosilane, 2-cyanoethyl trichlorosilane, 2-cyanoethylmethyl dichlorosilane, 3-cyanopropylmethyl diethoxysilane, 3-cyanopropylmethyl dichlorosilane, 3-cyanopropylmethyl dichlorosilane, 3-cyanopropyldimethyl ethoxysilane, 3-cyanopropylmethyl dichlorosilane, 3-cyanopropyl trichlorosilane, fluorinated alkyl silanes, and one type or two or more types selected from these can be used singly or in combination.

Among these, hexamethyl disilazane is preferably used in the hydrophobization treatment. Thereby, it is possible to further increase hydrophobicity of the particles. In addition, it is possible to easily and reliably further increase uniformity of the degree of the hydrophobic treatment at each portion (including the surface of the inside of a pore) of each particle or the particle surface.

In a case where the hydrophobization treatment using a silane compound is performed in a liquid phase, by immersing the particles to be subjected to the hydrophobization treatment in the liquid including the silane compound, it is possible to make a suitable desired reaction proceed, and it is possible to form a chemical adsorption film of the silane compound.

In addition, in a case where the hydrophobization treatment using a silane compound is performed in a gas phase, by exposing the particles 63 to be subjected to the hydrophobization treatment to the vapor of the silane compound, it is possible to make a suitable desired reaction proceed, and it is possible to form a chemical adsorption film of the silane compound.

Though the average grain size of the particles 63 configuring the powder for forming a three-dimensional object is not particularly limited, the average grain size of the particles 63 is preferably 1 micrometer to 25 micrometers, and more preferably 1 micrometer to 15 micrometers. Thereby, it is possible to make the mechanical strength of the three-dimensional structure 1 excellent, and it is possible to make the dimensional accuracy of the three-dimensional structure 1 excellent. In addition, it is possible to make fluidity of the powder for forming a three-dimensional object and fluidity of the composition for forming a three-dimensional object including the powder for forming a three-dimensional object excellent, and it is possible to make productivity of the three-dimensional structure excellent. Moreover, in the invention, the average particle size refers to an average particle size based on volume, and for example, after a sample is added to methanol, the mixture is dispersed for 3 minutes with an ultrasonic wave disperser, and the average particle size of the obtained dispersion is measured using an aperture of 50 micrometers by a Coulter counter method particle size distribution measuring instrument (TA-II type manufactured by COULTER ELECTRONICS INS.).

Though D_max of the particles 63 configuring the composition for forming a three-dimensional object is not particularly limited, D_max of the particles 63 is preferably 3 micrometers to 40 micrometers, and more preferably 5 micrometers to 30 micrometers. Thereby, it is possible to make the mechanical strength of the three-dimensional structure 1 excellent, and it is possible to make the dimensional accuracy of the three-dimensional structure 1 excellent. In addition, it is possible to make fluidity of the powder for forming a three-dimensional object and fluidity of the composition for forming a three-dimensional object including the powder for forming a three-dimensional object excellent, and it is possible to make productivity of the three-dimensional structure excellent. In addition, it is possible to more effectively prevent scattering of light by the particles 63 on the surface of the three-dimensional structure 1 to be manufactured.

In a case where the particles 63 are porous particles, the porosity of the porous particles is preferably equal to or greater than 50%, and more preferably 55% to 90%. Thereby, the particles can have sufficient space (pores) into which the curable resin enters, and it is possible to make the mechanical strength of the porous particles themselves excellent, and as a result, it is possible to make the mechanical strength of the three-dimensional structure 1 obtained by penetration of a binding resin into pores excellent. Moreover, in the present, the porosity of particles refers to a proportion (volume ratio) of pores which are present in particles with respect to the apparent volume of particles, and when the density of particles is defined as rho [g/cm³] and the true density of the constituent material of the particles is defined as rho₀ [g/cm³], the porosity of particles is a value represented by {(rho₀ - rho)/rho₀} x 100.

In a case where the particles 63 are porous particles, the average pore diameter (fine pore diameter) of the porous particles is preferably equal to or greater than 10 nm, and more preferably 50 nm to 300 nm. Thereby, it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent.

Though the particles 63 configuring the powder for forming a three-dimensional object may be any shape, the particles 63 are preferably a spherical shape. Thereby, it is possible to make fluidity of the powder for forming a three-dimensional object and fluidity of the composition for forming a three-dimensional object including the powder for forming a three-dimensional object excellent, it is possible to make productivity of the three-dimensional structure 1 excellent, and it is possible to make the dimensional accuracy of the three-dimensional structure 1 excellent.

The powder for forming a three-dimensional object may be powder including plural types of particles which have the above-described conditions (for example, constituent material of the particles, and type of hydrophobization treatment) different from each other.

The percentage of void of the powder for forming a three-dimensional object is preferably 70% to 98%, and more preferably 75% to 97.7%. Thereby, it is possible to make the mechanical strength of the three-dimensional structure excellent. In addition, it is possible to make fluidity of the powder for forming a three-dimensional object and fluidity of the composition for forming a three-dimensional object including the powder for forming a three-dimensional object excellent, it is possible to make productivity of the three-dimensional structure excellent, and it is possible to make the dimensional accuracy of the three-dimensional structure excellent. Moreover, in the invention, in a case where the inside of a container having a predetermined capacity (for example, 100 mL) is filled with the powder for forming a three-dimensional object, the percentage of void of the powder for forming a three-dimensional object refers to a ratio of the volume of pores which all the particles configuring the powder for forming a three-dimensional object have and the sum of the volume of voids which are present between the particles with respect to the capacity of the container, and when the bulk density of the powder for forming a three-dimensional object is defined as P [g/cm³] and the true density of the constituent material of the powder for forming a three-dimensional object is defined as P₀ [g/cm³], the percentage of void is a value represented by {(P₀ - P)/P₀} x 100.

The content of the powder for forming a three-dimensional object in the composition for forming a three-dimensional object is preferably 10% by mass to 90% by mass, and more preferably 15% by mass to 58% by mass. Thereby, it is possible to make the fluidity of the composition for forming a three-dimensional object excellent, and it is possible to make the mechanical strength of the finally obtained three-dimensional structure 1 excellent.

(Water-soluble Resin)
The composition for forming a three-dimensional object includes a plurality of the particles 63 and the water-soluble resin 64. By including the water-soluble resin 64, the particles 63 are bound (temporarily fixed) to each other (see Fig. 4), and it is possible to effectively prevent unintended scattering of the particles 63. Thereby, it is possible to improve safety of a worker and the dimensional accuracy of the manufactured three-dimensional structure 1.

In the invention, the water-soluble resin is not limited as long as at least a part thereof is soluble in water, and for example, a water-soluble resin having a solubility (mass soluble in 100 g water) of equal to or greater than 5 [g/100 g water] in water at 25 degrees centigrade is preferable, and a water-soluble resin having a solubility of equal to or greater than 10 [g/100 g water] in water at 25 degrees centigrade is more preferable.

Examples of the water-soluble resin 64 include synthetic polymers such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), sodium polyacrylate, polyacryl amide, modified polyamide, polyethylene imine, and polyethylene oxide, natural polymers such as cornstarch, mannan, pectin, agar, alginic acid, dextran, glues, and gelatin, and semi-synthetic polymers such as carboxymethyl cellulose, hydroxyethyl cellulose, oxidized starch, and modified starch, and one type or two or more types selected from these can be used singly or in combination.

Examples of the water-soluble resin product include methyl cellulose (manufactured by Shin-Etsu Chemicals Co., Ltd.: trade name "Metolose SM-15"), hydroxyethyl cellulose (manufactured by Fuji Chemical Industry Co., Ltd.: trade name "AL-15"), hydroxypropyl cellulose (manufactured by Nippon Soda Co., Ltd.: trade name "HPC-M"), carboxymethyl cellulose (Nichirin Chemical Co., Ltd.: trade name "CMC-30"), sodium (I) starch phosphate (manufactured by Matsutani Chemical Industry Co., Ltd.: trade name "Hoster 5100"), polyvinyl pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.: trade name "PVP K-90"), a methyl vinyl ether/maleic anhydride copolymer (manufactured by GAF Gantrez: trade name "AN-139"), polyacryl amide (manufactured by Wako Pure Chemical Industries, Ltd.), modified polyamide (modified nylon) (manufactured by Toray Industries, Inc.: trade name "AQ nylon"), polyethylene oxide (manufactured by Steel Chemical Co., Ltd.: trade name "PEO-1", manufactured by Meisei Chemical Works, Ltd.: trade name "Alkox"), an ethylene oxide/propylene oxide random copolymer (manufactured by Meisei Chemical Works, Ltd.: trade name "Alkox EP"), sodium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), and a carboxyvinyl polymer/cross-linked acryl-based water-soluble resin (manufactured by Sumitomo Seika Chemicals Co., Ltd.: trade name "AQUPEC").

Among these, in a case where the water-soluble resin 64 is polyvinyl alcohol, it is possible to make the mechanical strength of the three-dimensional structure 1 excellent. In addition, by adjusting the saponification degree and the polymerization degree, it is possible to more suitably control characteristics (for example, water solubility, water resistance, and the like) of the water-soluble resin 64 or characteristics (for example, viscosity, fixing force of the particles 63, wettability, and the like) of the composition for forming a three-dimensional object. Therefore, it is possible to more suitably cope with according to manufacture of the various three-dimensional structures 1. In addition, among various water-soluble resins, polyvinyl alcohol is inexpensive and a supply thereof is stable. Therefore, it is possible to manufacture the stable three-dimensional structure 1 while reducing the production cost.

In a case where the water-soluble resin 64 includes polyvinyl alcohol, the saponification degree of the polyvinyl alcohol is preferably 85 to 90. Thereby, it is possible to suppress decrease in the solubility of the polyvinyl alcohol in water. For this reason, in a case where the composition for forming a three-dimensional object includes water, it is possible to more effectively suppress reduction of the adhesion between adjacent unit layers.

In a case where the water-soluble resin 64 includes polyvinyl alcohol, the polymerization degree of the polyvinyl alcohol is preferably 300 to 1000. Thereby, in a case where the composition for forming a three-dimensional object includes water, it is possible to make the mechanical strength of each unit layer or the adhesion between adjacent unit layers excellent.

In addition, in a case where the water-soluble resin 64 is polyvinyl pyrrolidone (PVP), the following effects are obtained. That is, since polyvinyl pyrrolidone has excellent adhesion with respect to various materials such as glass, metal, and plastic, it is possible to make strength and stability of the shape of the portion where the ink is not applied in the composition layer for forming a three-dimensional object 6' excellent, and it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent. In addition, since polyvinyl pyrrolidone shows high solubility in various organic solvents, in a case where the a composition for forming a three-dimensional object includes an organic solvent, it is possible to make the fluidity of the composition for forming a three-dimensional object excellent, it is possible to suitably form the composition layer for forming a three-dimensional object 6' in which unintentional variations in the thickness are more effectively prevented, and it is possible to make the dimensional accuracy of the finally obtained three-dimensional structure 1 excellent. In addition, since polyvinyl pyrrolidone has a suitable affinity with the powder for forming a three-dimensional object, polyvinyl pyrrolidone does not sufficiently enter into the pore 611 described above, and wettability with respect to the surface of the particles 63 is relatively high. For this reason, it is possible to more effectively exhibit the temporarily fixing function described above. In addition, since polyvinyl pyrrolidone has an antistatic function, in a case where the powder which is not subjected to a pasting treatment is used as the composition for forming a three-dimensional object in the filling step, it is possible to effectively prevent unintended scattering of the powder. In addition, in a case where the powder which is subjected to a pasting treatment is used as the composition for forming a three-dimensional object in the filling step, when the paste-shaped composition for forming a three-dimensional object includes polyvinyl pyrrolidone, it is possible to effectively prevent bubbles from being entrained into the composition for forming a three-dimensional object, and in the filling step, it is possible to more effectively prevent occurrence of defects due to entrainment of bubbles.

In a case where the water-soluble resin 64 includes polyvinyl pyrrolidone, the weight average molecular weight of the polyvinyl pyrrolidone is preferably 10000 to 1700000, and more preferably 30000 to 1500000. Thereby, it is possible to more effectively exhibit the function described above.

In the composition for forming a three-dimensional object, the water-soluble resin 64 preferably is in a liquid state (for example, a dissolved state, a molten state, or the like) in at least the filling step. Thereby, it is possible to easily and reliably further increase uniformity in the thickness of the composition layer for forming a three-dimensional object 6' which is formed by using the composition for forming a three-dimensional object.

The content of the water-soluble resin 64 in the composition for forming a three-dimensional object is preferably equal to or less than 15% by volume, and more preferably 2% by volume to 5% by volume with respect to a bulk volume of the powder for forming a three-dimensional object. Thereby, while sufficiently exhibiting the function of the water-soluble resin 64 as described above, it is possible to ensure a wider space into which the binding ink 4C penetrates, and it is possible to make the mechanical strength of the three-dimensional structure 1 excellent.

(Solvent)
The composition for forming a three-dimensional object may include a solvent in addition to the water-soluble resin 64 as described above and the powder for forming a three-dimensional object. Thereby, it is possible to make fluidity of the composition for forming a three-dimensional object excellent, and it is possible to make productivity of the three-dimensional structure 1 excellent.

The solvent is preferably a solvent which can dissolve the water-soluble resin 64. Thereby, it is possible to make fluidity of the composition for forming a three-dimensional object favorable, and it is possible to more effectively prevent unintended variations in the thickness of the composition layer for forming a three-dimensional object 6' which is formed by using the composition for forming a three-dimensional object. In addition, when the composition layer for forming a three-dimensional object 6' from which the solvent is removed is formed, it is possible to attach the water-soluble resin 64 to the particles 63 with higher uniformity over the entire composition layer for forming a three-dimensional object 6', and it is possible to more effectively prevent occurrence of unintended constitution unevenness. For this reason, it is possible to more effectively prevent occurrence of unintended variations in the mechanical strength at each portion of the finally obtained three-dimensional structure 1, and it is possible to further increase the reliability of the three-dimensional structure 1.

Examples of the solvent configuring the composition for forming a three-dimensional object include water; alcoholic solvents such as methanol, ethanol, and isopropanol; ketone-based solvents such as methyl ethyl ketone and acetone; glycol ether-based solvents such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, glycol ether acetate-based solvents such as propylene glycol 1-monomethyl ether 2-acetate and propylene glycol 1-monoethyl ether 2-acetate; polyethylene glycol, and polypropylene glycol, and one type or two or more types selected from these can be used singly or in combination.

Among these, the composition for forming a three-dimensional object preferably includes water. Thereby, it is possible to more reliably dissolve the water-soluble resin 64, and it is possible to make fluidity of the composition for forming a three-dimensional object and uniformity of the constitution of the composition layer for forming a three-dimensional object 6' which is formed by using the composition for forming a three-dimensional object excellent. In addition, water is easily removed after the composition layer for forming a three-dimensional object 6' is formed, and does not give adverse effects even in a case where water remains in the three-dimensional structure 1. In addition, water is also advantageous from the viewpoint of safety with respect to human body and environmental issues.

In a case where the composition for forming a three-dimensional object includes a solvent, the content of the solvent in the composition for forming a three-dimensional object is preferably 5% by mass to 75% by mass, and more preferably 35% by mass to 70% by mass. Thereby, since effects due to including the solvent as described above can be more significantly exhibited, it is possible to easily remove the solvent in a short period of time in the manufacturing step of the three-dimensional structure 1, including a solvent is advantageous from the viewpoint of productivity improvement of the three-dimensional structure 1.

In particular, in a case where the composition for forming a three-dimensional object includes water as a solvent, the content of water in the composition for forming a three-dimensional object is preferably 20% by mass to 73% by mass, and more preferably 50% by mass to 70% by mass. Thereby, effects as described above are more significantly exhibited.

(Other Components 3)
In addition, the composition for forming a three-dimensional object may include components other than the components described above. Examples of such components include a polymerization initiator; a polymerization accelerator; a penetration enhancer; a wetting agent (humectant); a fixing agent; a fungicide; a preservative; an antioxidant; an ultraviolet absorbent; a chelating agent; and a pH adjusting agent.

The three-dimensional structure of the invention can be manufactured by using the manufacturing method as described above, the three-dimensional structure manufacturing apparatus, and an ink set. Thereby, it is possible to provide a three-dimensional structure of which the outer surface has high mechanical strength and on which a fine color expression may be performed.

Use of the three-dimensional structure of the invention is not limited, and items for appreciation and articles for exhibitions such as a doll and a figure; and medical devices such as an implant can be exemplified.

In addition, the three-dimensional structure of the invention may be applied to any of a prototype, mass-produced products, and tailor made products.

In addition, the three-dimensional structure of the invention may be a model (for example, models of vehicles such as an automobile, a motorcycle, a ship, and an airplane, buildings, organisms such as an animal and a plant, natural objects (not organism) such as a stone, and various foods).

Hereinabove, the preferred embodiments of the invention have been described, but the invention is not limited to these embodiments.

For example, in the embodiment described above, description has been made focused on a case where the ink for forming an outermost layer, the ink for forming a sacrificial layer, or the binding ink is discharged by an ink jet method, however, each ink may be applied by other methods (for example, other printing methods).

In addition, in the manufacturing method of the invention, a pretreatment step, an intermediate treatment step, or a post-treatment step may be performed, as necessary.

As the pretreatment step, a cleaning step of the stage or the like can be exemplified.

As the post-treatment step, a cleaning step, a shape adjusting step of performing deburring or the like, and an additional curing treatment for increasing the degree of cure of a curable resin configuring the outermost layer can be exemplified.

In addition, in the embodiment described above, description has been made focused on a case where the ink discharge step is performed by an ink jet method, however, the ink discharge step may be performed by using other methods (for example, other printing methods).

In addition, in the embodiment described above, a case where the particles in the composition layer for forming a three-dimensional object are bound with the binding ink has been described, however, the particles may not be bound with the binding ink.

1 ... Three-dimensional structure
1' ... Temporarily formed body
4A ... Ink for forming an outermost layer
4B ... Ink for forming a sacrificial layer
4C ... Binding ink
6 ... Powder binding layer
6' ... Composition layer for forming a three-dimensional object
7 ... Outermost layer
8 ... Sacrificial layer
20 ... Computer
21 ... Control portion
22 ... CPU
23 ... Memory portion
24 ... Receiving portion
25 ... Image producing portion
28 ... Input/output interface
29 ... Data bus
30 ... Forming portion
40 ... Ink discharge portion
41 ... Liquid droplet discharge head
42 ... X-direction moving portion
43 ... Y-direction moving portion
44 ... Curable resin
50 ... Powder supply portion
60 ... Powder control portion
61 ... Blade
62 ... Guide rail
63 ... Particles
64 ... Water-soluble resin
70 ... Light source
80 ... Forming stage
100 ... Three-dimensional structure manufacturing apparatus
231 ... Control program
232 ... Data expanding portion
611 ... Pore

Claims

A method for manufacturing a three-dimensional structure by stacking layers formed by using an ink containing a curable resin, comprising:
an ink discharge step of discharging an ink for forming an outermost layer to a region to become the outermost layer of the three-dimensional structure of the layer and discharging an ink for forming a sacrificial layer to a region on a surface side of the outermost layer which is adjacent to the region to become the outermost layer of the layer;
a curing step of curing the ink for forming an outermost layer and the ink for forming a sacrificial layer discharged; and
a filling step of filling a region surrounded by a cured product of the ink for forming an outermost layer with a composition for forming a three-dimensional object including powder for forming a three-dimensional object configured of particles and forming a composition layer for forming a three-dimensional object.
The method for manufacturing a three-dimensional structure according to Claim 1,
wherein in the filling step, a planarization treatment is performed with respect to the filled composition for forming a three-dimensional object based on a height of the cured product of the ink for forming an outermost layer.
The method for manufacturing a three-dimensional structure according to Claim 1 or 2, comprising,
a powder binding step of discharging a binding ink containing a curable resin and forming a powder binding layer with respect to the composition layer for forming a three-dimensional object.
The method for manufacturing a three-dimensional structure according to Claim 3,
wherein the powder binding step in formation of the layer of a kth layer (k is an integer of equal to or greater than 1) is performed together with the ink discharge step in formation of the layer of a (k+1)th layer (k is an integer of equal to or greater than 1).
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 3,
wherein in the ink discharge step, the ink for forming an outermost layer is discharged to a region to become the outermost layer of the three-dimensional structure of a plurality of the layers, and the ink for forming a sacrificial layer for forming the sacrificial layer is discharged to a region on a surface side of the outermost layer which is adjacent to the region to become the outermost layer of the plurality of the layers.
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 5,
wherein the ink for forming an outermost layer includes one type or two or more types selected from the group consisting of 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, polyether-based aliphatic urethane (meth)acrylate oligomer, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 6,
wherein the ink for forming a sacrificial layer includes one type or two or more types selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, polyethylene glycol di(meth)acrylate, (meth)acryloyl morpholine, and 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 7,
wherein the ink for forming an outermost layer and the ink for forming a sacrificial layer include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and/or 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a polymerization initiator.
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 8,
wherein as the ink for forming an outermost layer, in addition to a coloring ink containing a colorant, a colorless ink not containing a colorant is used, the colorless ink is used for forming a region near the outer surface of the three-dimensional structure, of the outermost surface, and the coloring ink is used for forming a region on the inner side than the region.
The method for manufacturing a three-dimensional structure according to any one of Claims 1 to 9,
wherein as the ink for forming an outermost layer, the coloring ink containing a colorant is used, a chromatic color ink and a white ink are used as the coloring ink, and the white ink is used for forming a region on the inner side of the region formed by using the chromatic color ink.
A three-dimensional structure manufactured by using the method according to any one of Claims 1 to 10.