JP2017001226A - Method for forming three dimensional molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three dimensional molded article excellent in stability of used ink composition, small in volume shrinkage during curing, excellent in moldability, small in yellow coloration of a resulting three dimensional molded article and small in fingerprint residue when the resulting three dimensional molded article is toughed with hands.SOLUTION: There is provided a manufacturing method of a three dimensional molded article by using an ink composition containing 4 to 20 mass% of a photoinitiator selected from a group consisting of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-on, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-on, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropane-1-on and a compound by multifunctionalizing the above described initiators and using an LED light source having a peak at wavelength between 275 to 310 nm in a curing process.SELECTED DRAWING: None

Description

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

The optical three-dimensional modeling method is a method of forming a three-dimensional modeled object having a desired shape by selectively supplying energy necessary for the photocurable composition.
As a representative example of the three-dimensional modeling method, the cured layer is selectively irradiated with light, for example, an ultraviolet laser so that a cured layer having a desired pattern is obtained on the liquid surface of the photocurable composition placed in the container. Next, a photocurable composition is supplied in a layer form on the cured layer, and then light is selectively irradiated in the same manner as described above to form a cured layer continuous with the cured layer. This is a method of finally obtaining a desired three-dimensional three-dimensional structure by repeating this lamination operation. This three-dimensional modeling method is attracting attention because even if the shape of a model to be manufactured is complicated, the target model can be easily obtained in a short time.
In recent years, an optical modeling method using an ink jet method has been proposed. Compared with the conventional method, a liquid photocurable resin discharged from an ink jet nozzle can be cured and laminated to perform an optical modeling. There is an advantage that it is not necessary to install a resin solution tank or a dark room. In addition to being compact and miniaturized, the stereolithography machine is attracting attention as 3D CAD that can freely create a three-dimensional model by using a CAD (Computer Aided Design) system.
Examples of conventional stereolithography include those described in Patent Documents 1 and 2.

JP 2012-111226 A US Pat. No. 7,851,122

Conventional ultraviolet curable ink jet three-dimensional structures have been widely used for manufacturing industrial product prototypes, and therefore, there has been little demand for the color of the molding itself. Recently, three-dimensional printing has been used for small-lot toy products (eg, anime character dolls), stationery (eg, ballpoint pens), ornaments, etc. It has come to be strongly desired. However, when the conventional ultraviolet curable ink jet method for forming a three-dimensional structure is used, the three-dimensional structure has a large yellow coloration, and there is a great limitation especially on the use of a transparent or white model material.
The problem to be solved by the present invention is that the ink composition used is excellent in stability, volume shrinkage at the time of curing is small, moldability is excellent, yellow coloration of the obtained three-dimensional structure is small, and the obtained three-dimensional structure is obtained The object is to provide a method for forming a three-dimensional structure with a small fingerprint trace when an object is touched by hand.

Said subject was achieved by the means as described in <1> below. They are listed below together with <2> to <11> which are preferred embodiments.
<1> A heating step of heating the ink composition to a range of 40 ° C. to 80 ° C., the heated ink composition is ejected by an inkjet head, and an ink layer is formed based on cross-sectional information of the three-dimensional structure. A discharge step and a curing step of curing the ink layer with actinic rays, wherein the ink composition contains at least one (meth) acrylate compound, and the total (meth) acrylate in the ink composition The content of the monofunctional (meth) acrylate compound with respect to 100 parts by mass of the compound is 50 to 95 parts by mass, and the ink composition is 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane. -1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propane- -One, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one, and any one of the above initiators 4 to 20% by mass of one or more photopolymerization initiators selected from the group consisting of polyfunctionalized compounds with respect to the total mass of the ink composition, and the curing step has a wavelength of 275 to 310 nm. A method for forming a three-dimensional structure characterized by using an LED light source having a peak in between,
<2> The method for forming a three-dimensional structure according to <1>, wherein the content of the photopolymerization initiator in the ink composition is 6 to 12% by mass with respect to the total mass of the ink composition,
<3> The ink composition contains 1 to 3% by mass of an acrylic resin having a glass transition temperature of 50 ° C. to 120 ° C. and a weight average molecular weight of 5,000 to 200,000 based on the total mass of the ink composition. Containing, a method for forming a three-dimensional structure according to <1> or <2>,
<4> The method for forming a three-dimensional structure according to any one of <1> to <3>, wherein the ink composition does not substantially contain a colorant.
<5> The method for forming a three-dimensional structure according to any one of <1> to <3>, wherein the ink composition contains titanium oxide as a white colorant.
<6> The method for forming a three-dimensional structure according to <5>, wherein the content of titanium oxide in the ink composition is 1 to 5% by mass relative to the total mass of the ink composition,
<7> The method for forming a three-dimensional structure according to any one of <1> to <6>, wherein the ink composition contains two or more of the photopolymerization initiators.
<8> The method for forming a three-dimensional structure according to <7>, wherein the ink composition contains two or three types of the photopolymerization initiator,
<9> The method for forming a three-dimensional structure according to <3>, wherein the acrylic resin is a methyl methacrylate homopolymer and / or a copolymer,
<10> The method for forming a three-dimensional structure according to <9>, wherein the acrylic resin is a methyl methacrylate copolymer,
<11> The three-dimensional image according to any one of <1> to <10>, wherein the ink composition contains a bifunctional (meth) acrylate oligomer having a weight average molecular weight of 2,000 or more and 20,000 or less. Method for forming a modeled object.

  According to the present invention, the ink composition to be used is excellent in stability, volume shrinkage at the time of curing is small, moldability is excellent, yellow coloring of the obtained three-dimensional structure is small, and the obtained three-dimensional structure is obtained by hand. It is possible to provide a method of forming a three-dimensional structure with a small fingerprint trace when touched.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present invention, the description of “lower limit to upper limit” representing a numerical range represents “lower limit or higher and lower limit or lower”, and the description of “upper limit to lower limit” represents “lower limit or higher and lower limit or higher”. That is, it represents a numerical range including an upper limit and a lower limit.
Furthermore, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what does not have a substituent and what has a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
“(Meth) acrylate” and the like are synonymous with “acrylate and / or methacrylate” and the like.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.
In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.

(Method for forming a three-dimensional structure)
In the method for forming a three-dimensional structure of the present invention, a heating step of heating the ink composition to a range of 40 ° C. to 80 ° C., the heated ink composition is discharged by an inkjet head, and cross-sectional information of the three-dimensional structure is obtained. The ink composition contains at least one (meth) acrylate compound, and includes a discharging step of forming an ink layer and a curing step of curing the ink layer with actinic rays. The content of the monofunctional (meth) acrylate compound with respect to 100 parts by mass of the total (meth) acrylate compound in the composition is 50 to 95 parts by mass, and the ink composition contains 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy. 2-Methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy 2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one, and 4-20 mass% of 1 or more types of photoinitiators selected from the group which consists of a compound which multifunctionalized any one said initiator with respect to the total mass of an ink composition, The curing step uses an LED (light emitting diode) light source having a peak between wavelengths of 275 to 310 nm.

As a result of detailed studies, the inventor used an ink composition having a specific composition and cured it with an LED light source having a peak between 275 and 310 nm, thereby stabilizing the ink composition used. It is found that the volumetric shrinkage at the time of curing is small, the moldability is excellent, the yellow coloration of the obtained three-dimensional structure is small, and the fingerprint remains when the obtained three-dimensional structure is touched by hand. It was.
The “three-dimensional modeling” in the present invention is also referred to as 3D printing or 3D printing, and is a modeling method in which a plurality of ink layers are stacked and is preferably a modeling method in which 50 or more layers are stacked. In the present invention, the discharging step and the curing step are preferably repeated 50 times or more to laminate 50 or more layers.
Although the detailed mechanism in which the above effect is manifested is unknown, the ink composition contains a large amount of a monofunctional (meth) acrylate compound, contains a specific amount of a specific photopolymerization initiator, and has a wavelength of 275 to 310 nm. It is estimated that the effect is expressed in concert by curing using an LED light source having a peak in between.
The method for forming a three-dimensional structure of the present invention can be suitably used for, for example, forming a medical three-dimensional structure such as a blood vessel, a toy, a figure, and the like.

In the method for forming a three-dimensional structure of the present invention, the ink composition may be used alone or in combination of two or more.
The ink composition is preferably a white ink composition or a clear ink composition.
In the method for forming a three-dimensional structure according to the present invention, an ink composition other than the ink composition may be used. Examples of the other ink composition include an ink composition containing an organic pigment.
In the method for forming a three-dimensional structure of the present invention, not only the ink composition (ink material for model material) but also an ink composition for support material may be used in combination as the ink composition.
The “model material” is a material that is cured to become a target three-dimensional structure, and the “support material” is printed around or inside the model material in the three-dimensional structure. Is a material that is removed after shaping is completed.

<Heating process>
The method for forming a three-dimensional structure of the present invention includes a heating step of heating the ink composition to a range of 40 ° C to 80 ° C.
A preferred embodiment of the ink composition used in the method for forming a three-dimensional structure of the present invention will be described later.
There is no restriction | limiting in particular as a heating means of an ink composition, A well-known heating means can be used.
As the heating means, a heating means provided in an ink jet discharge apparatus used in a discharge process described later can be suitably exemplified. As an example, there is a heating means for performing heat insulation and heating from the ink composition supply tank to the ink jet head portion.
The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping site and perform heating control according to the flow rate of the ink composition and the environmental temperature. The temperature sensor can be provided near the ink composition supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the start-up time of the inkjet discharge apparatus that requires heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.
In addition, the actinic ray curable ink jet ink composition generally has a higher viscosity than the water-based ink composition that is usually used in ink jet ejection, and therefore the viscosity fluctuation due to temperature fluctuations during ejection is large. Viscosity fluctuations in the ink composition have a large effect on changes in the droplet size and droplet ejection speed, which in turn can cause image quality deterioration. Therefore, the temperature of the ink composition during ejection should be as constant as possible. It is preferable to keep. Therefore, in the present invention, the temperature control range of the ink composition is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set temperature ± 1 ° C. .

In the method for forming a three-dimensional structure of the present invention, the heating step may be performed a plurality of times, or the heating means is performed once, and the ink composition is kept as it is in the range of 40 ° C to 80 ° C. May be.
In the method for forming a three-dimensional structure of the present invention, the temperature of the ink composition at the time of discharging with an inkjet head is preferably 40 ° C. to 80 ° C. It is preferable to perform the heating step again or keep the temperature so that the ink composition is kept within the range.

<Discharge process>
The method for forming a three-dimensional structure of the present invention includes a discharge step of discharging the ink composition heated in the heating step with an inkjet head and forming an ink layer based on cross-sectional information of the three-dimensional structure. .
The cross-sectional information of the three-dimensional structure used in the discharge process is not particularly limited, and cross-section data corresponding to the three-dimensional shape of the desired three-dimensional structure may be created in an arbitrary format according to the apparatus to be used. As a method for generating cross-sectional information of a three-dimensional structure, for example, three-dimensional CAD data of an object to be modeled is used, and the CAD data is used as data for three-dimensional modeling, for example, three-dimensional STL (Stereo Lithography) data. Further, the data of each cross-section (layer) sliced at a pitch (layer thickness) corresponding to the thickness of one ink layer in any one direction (for example, the height direction) from the three-dimensional STL data. The method of producing | generating is mentioned. The pitch can be appropriately determined according to the ink composition to be used, desired accuracy, and the like. Moreover, the data of each said cross-section (layer) may have the color information (coloring data) of each part as needed.
Furthermore, it is also possible to use data and texture of the three-dimensional colored shape measured by the three-dimensional shape input device.
In addition, in the ejection step, when using not only the ink composition for the model material such as the ink composition but also the ink composition for the support material, the “cross-sectional information of the three-dimensional structure” refers to the three-dimensional structure itself Needless to say, not only the cross-section information of the support material but also the cross-section information of the support material provided when the three-dimensional structure is formed.

In the ejection step, an ink layer can be formed by ejecting the ink composition with an inkjet head using a known inkjet ejection device or inkjet ejection means.
The ink composition forming the ink layer only needs to contain at least the ink composition. For example, in order to form a color three-dimensional structure, two or more ink compositions including the ink composition are used. In addition to the above ink composition, it is preferable to use an ink composition for a support material as necessary.
The ink layer formed of the support material ink composition may be formed in an arbitrary shape. For example, an ink layer with an ink composition for a support material may be formed so that a minimum necessary support material is formed when forming a three-dimensional structure, The ink layer of the support material ink composition may be formed with a large margin so that a sufficient support material is formed inside.
In addition, if a support material is unnecessary for forming a three-dimensional structure having a desired shape, the support material ink composition may not be used.

The thickness of the ink layer in the ejection step is not particularly limited, and may be determined according to the ink composition to be used, desired accuracy, etc., as described above, but is preferably 0.1 to 200 μm. 1 to 150 μm is more preferable, and 10 to 100 μm is still more preferable.
The resolution for discharging the ink composition by the inkjet head in the discharging step is not particularly limited, and can be appropriately selected according to the accuracy of the desired three-dimensional structure and the accuracy of the cross-sectional information of the three-dimensional structure.
The ink layer formed in the first ejection step in the method for forming a three-dimensional structure of the present invention may be directly formed on the base or modeling table of the three-dimensional modeling apparatus to be used, or an arbitrary substrate separately prepared, You may form on a support body or articles | goods, You may form the ink composition for support materials provided by methods other than the said discharge process on one layer or multiple layers.
The ink layer formed in the second and subsequent ejection steps in the method for forming a three-dimensional structure of the present invention is preferably formed on an already formed ink layer.

<Curing process>
The method for forming a three-dimensional structure of the present invention includes a curing step of curing the ink layer formed in the ejection step with actinic rays, and in the curing step, an LED light source having a peak between wavelengths 275 to 310 nm is used. .
In the present invention, “having a peak between wavelengths 275 to 310 nm” means that the maximum value of emission intensity is between wavelengths 275 to 310 nm when the emission spectrum of the light source is measured.
The peak wavelength of actinic rays used in the curing step is between 275 and 310 nm, preferably between 2800 and 305 nm, and more preferably between 280 and 300 nm. Within the above range, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller.

As the actinic ray source in the curing step, an LED light source having a peak between wavelengths 275 to 310 nm is used. By using the LED light source, the fingerprint trace residue when the obtained three-dimensional structure is touched with a hand immediately after formation is reduced.
The maximum illumination intensity on the ink layer of the LED light source in the curing step is preferably 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, 50 to 800 mW / Particularly preferred is cm ² .
The ink layer is irradiated with actinic rays preferably for 0.01 to 120 seconds, more preferably for 0.1 to 90 seconds.

In the method for forming a three-dimensional structure of the present invention, the discharging step and the curing step are repeated 50 times or more. By repeating one set of the discharge step and the curing step, a three-dimensional structure is formed layer by layer based on the cross-sectional information, and in the method for forming a three-dimensional structure of the present invention, 50 layers or more are formed. The If the number of repetitions is 50 times or more, the effect of softness in the present invention is sufficiently obtained. From the viewpoint of further exerting the softness effect in the present invention, the thickness of the molded product is preferably 1 mm or more, and more preferably 1 cm or more. Therefore, the method for forming a three-dimensional structure of the present invention is preferably performed by repeating the discharge step and the curing step 100 times or more, more preferably 300 times or more.
Moreover, you may perform the said heating process again as needed, while repeating the said discharge process and the said hardening process.
Further, if necessary, a smoothing step of smoothing the surface of the ink layer with a roller or the like may be included between the discharging step and the curing step.

When an ink composition for a support material is used in combination as an ink composition, the method for forming a three-dimensional structure according to the present invention is a removal method for removing a support material obtained by curing the ink composition for a support material from the obtained three-dimensional structure. Process.
The method for removing the support material is not particularly limited, and may be physically removed by pulverization or the like, or may be chemically removed by dissolution or the like.
For example, if the support material has a hardness lower than that of the model material and can be crushed, it is preferably physically removed by pulverization or the like. Moreover, when a support material is a water-soluble hardened | cured material, it is preferable to contact and remove with an aqueous liquid.

The method for forming a three-dimensional structure of the present invention may include other known steps as necessary.
In the method for forming a three-dimensional structure of the present invention, post-processing steps such as cleaning, heat treatment, resin or wax penetration, and polishing may be performed on the obtained three-dimensional structure as necessary. The cleaning may be performed by blowing or brushing the three-dimensional structure to remove the residue of the support material left in the gap. In order to increase the strength and durability of the three-dimensional structure, the heat treatment can be performed according to the composition of the used ink composition for a model material. The wax permeation can reduce the porosity, make the three-dimensional structure water-resistant, make it easier to polish, and improve surface gloss. The polishing finish can improve the surface smoothness and improve the texture, glossiness, and the like.
Moreover, the formation method of the three-dimensional structure of this invention may include the process of coloring the surface of the obtained three-dimensional structure as needed.

<Ink composition>
The method for forming a three-dimensional structure of the present invention contains at least one (meth) acrylate compound, and contains a monofunctional (meth) acrylate compound with respect to 100 parts by mass of the total (meth) acrylate compound in the ink composition. The amount is 50 to 95 parts by mass, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2 -Hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one And one or more photopolymerization initiators selected from the group consisting of compounds obtained by polyfunctionalizing any one of the above initiators (hereinafter, Also referred to as a specific photopolymerization initiator ".) And with respect to the total mass of the ink composition, using at least an ink composition containing 4-20 wt%.
The ink composition preferably contains substantially no colorant other than white.
“Containing substantially no colorant” means that no colorant is contained, or the content of the colorant is more than 0% by mass and 0.5% by mass or less with respect to the total mass of the ink composition. Means.
The ink composition does not contain a colorant other than white, or the content of a colorant other than white exceeds 0% by mass and is 0.1% by mass or less based on the total mass of the ink composition. It is preferable that no colorant other than white is contained, or the content of a colorant other than white is more than 0% by mass and 0.01% by mass or less with respect to the total mass of the ink composition. More preferably, it is particularly preferable not to contain a colorant other than white.

-Specific photopolymerization initiator-
The above ink composition has 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl]-as a photopolymerization initiator. 2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropane-1- On and one or more photopolymerization initiators selected from the group consisting of compounds obtained by polyfunctionalizing any one of the above initiators in an amount of 4 to 20% by mass based on the total mass of the ink composition contains.
The ink composition contains one or more kinds of specific photopolymerization initiators, preferably two or more kinds, more preferably 2 to 4 kinds, still more preferably 2 or 3 kinds. It is particularly preferable to contain the types. In the above embodiment, the moldability and ink stability are excellent.
The ink composition contains the specific photopolymerization initiator in an amount of 4 to 20% by mass with respect to the total mass of the ink composition, preferably 5 to 15% by mass, and more preferably 6 to 12% by mass. More preferred. Within the above range, the moldability and the ink stability are excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller.

The specific photopolymerization initiator preferably includes at least 1-hydroxycyclohexyl phenyl ketone, and includes 1-hydroxycyclohexyl phenyl ketone and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl- More preferably, it contains at least 1-propan-1-one. In the above aspect, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched with a hand becomes smaller.
Specific photopolymerization initiators include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy -2-methyl-1-propan-1-one and 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one It is preferable to include a compound obtained by polyfunctionalizing any one of the initiators. In the above embodiment, the moldability is more excellent.
Examples of the polyfunctionalized compound include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy. -2-methyl-1-propan-1-one or 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one Any compound may be used as long as it has a polyfunctionalized structure in which two or more initiators are combined by a linking group.
Among them, examples of the multifunctional compound include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2. -Hydroxy-2-methyl-1-propan-1-one and 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropane-1 -It is preferably a compound having two or more structures in which one hydrogen atom is removed from one initiator selected from the group consisting of 1- [1- (4- (2-hydroxyethoxy) phenyl] -2- A compound having two or more structures in which one hydrogen atom is removed from hydroxy-2-methyl-1-propan-1-one is more preferable.

  The ink composition may contain a photopolymerization initiator other than the specific photopolymerization initiator as a photopolymerization initiator, but from the viewpoint of suppressing yellow coloring, a photopolymerization initiator other than the specific photopolymerization initiator. Even if it contains, it is preferable that it is 1 mass% or less, and it is more preferable not to contain photoinitiators other than a specific photoinitiator.

-(Meth) acrylate compound-
The ink composition contains at least a (meth) acrylate compound as a polymerizable compound, and the content of the monofunctional (meth) acrylate compound with respect to 100 parts by mass of the total (meth) acrylate compound in the ink composition is 50. ~ 95 parts by mass.
That is, the ink composition contains a monofunctional (meth) acrylate compound and a polyfunctional (meth) acrylate compound.
The content of the monofunctional (meth) acrylate compound with respect to 100 parts by mass of the total (meth) acrylate compound in the ink composition is 50 to 95 parts by mass, preferably 60 to 95 parts by mass, and 70 to 90. It is more preferable that it is a mass part, and it is especially preferable that it is 75-85 mass part. When it is in the above range, the moldability is excellent, the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller, and the volume shrinkage can be further reduced.
The (meth) acrylate compound may be an acrylate compound or a methacrylate compound, but is preferably an acrylate compound from the viewpoint of viscosity, moldability, and polymerization rate.
The content of the polymerizable compound in the ink composition is preferably 60 to 95% by mass, more preferably 70 to 95% by mass, and particularly preferably 80 to 90% by mass. When it is in the above range, the moldability is excellent, the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller, and the volume shrinkage can be further reduced.

The monofunctional (meth) acrylate compound is a (meth) acrylate monomer A having a glass transition temperature of the following homopolymer of 25 ° C. or more and 120 ° C. or less, and a glass transition temperature of the following homopolymer of −60 ° C. or more and less than 25 ° C. ( It is preferable to include a (meth) acrylate monomer B, and the glass transition temperature of the following homopolymer is 25 ° C. or higher and 120 ° C. or lower, and the glass transition temperature of the following homopolymer is −60 ° C. or higher and lower than 25 ° C. (Meth) acrylate monomer B is more preferable.
In the present invention, the glass transition temperature (Tg) of a monomer homopolymer (homopolymer) is measured by a dynamic viscoelasticity meter (DMA). The glass transition temperature of the homopolymer may depend on the degree of polymerization, but if a homopolymer having a weight average molecular weight of 10,000 or more is prepared and measured, the influence of the degree of polymerization can be ignored. In the present invention, a value measured using a sample polymerized until the influence of the degree of polymerization can be ignored is defined as a glass transition temperature (Tg).

<< (Meth) acrylate monomer A having a glass transition temperature of 25 ° C to 120 ° C >>
The ink composition preferably contains a (meth) acrylate monomer A having a homopolymer glass transition temperature of 25 ° C. or higher and 120 ° C. or lower.
The (meth) acrylate monomer A may be an acrylate compound or a methacrylate compound, but is preferably an acrylate compound.
The glass transition temperature of the homopolymer of (meth) acrylate monomer A is 25 ° C. or higher and 120 ° C. or lower, preferably 30 ° C. or higher and 100 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower. It is excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said aspect, and it can suppress the failure generation | occurrence | production at the time of support material removal.
The (meth) acrylate monomer A may be a monofunctional acrylate monomer or a polyfunctional acrylate monomer, but is preferably a monofunctional acrylate monomer.
Furthermore, the (meth) acrylate monomer A is preferably an acrylate monomer having a hydrocarbon ring structure.

Specific examples of the (meth) acrylate monomer A include isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, t-butyl acrylate, t-butyl methacrylate, t-butylcyclohexyl acrylate, methyl methacrylate, and ethyl methacrylate. , Propyl methacrylate, phenyl acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, dicyclopentanyl acrylate, 2-hydroxyethyl methacrylate, 2-methacryloyloxyethyl hexahydrophthalic acid, 3-hydroxypropyl methacrylate 2-methacryloyloxyethylphthalic acid, 3,3,5- Trimethyl cyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentenyl acrylate, 1,6-hexanediol diacrylate.
Among these, as the (meth) acrylate monomer A, a monomer selected from the group consisting of isobornyl acrylate, t-butylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, and dicyclopentanyl acrylate is used. It is preferable to include isobornyl acrylate and / or t-butylcyclohexyl acrylate. It is excellent in the tensile strength of the obtained three-dimensional structure as it is the said aspect, and it can suppress the failure generation | occurrence | production at the time of support material removal.

The (meth) acrylate monomer A may be contained singly or in combination of two or more.
The content of the (meth) acrylate monomer A with respect to the total mass of the ink composition is preferably 10 to 80% by mass, more preferably 20 to 75% by mass, and 30 to 70% by mass. Is more preferable, and 40 to 60% by mass is particularly preferable. It is excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said range, and it can suppress the failure generation | occurrence | production at the time of support material removal.

<< (Meth) acrylate monomer B having homopolymer glass transition temperature of -60 ° C or higher and lower than 25 ° C >>
The ink composition preferably contains a (meth) acrylate monomer B having a homopolymer glass transition temperature of −60 ° C. or higher and lower than 25 ° C.
The (meth) acrylate monomer B may be an acrylate compound or a methacrylate compound, but is preferably an acrylate compound.
The glass transition temperature of the homopolymer of (meth) acrylate monomer B is −60 ° C. or higher and lower than 25 ° C., preferably −30 ° C. or higher and 10 ° C. or lower, and more preferably −10 ° C. or higher and 10 ° C. or lower. preferable. It is excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said aspect, and is excellent in a moldability.
In addition, the (meth) acrylate monomer B may be a monofunctional acrylate monomer or a polyfunctional acrylate monomer, but is preferably a monofunctional acrylate monomer.
Furthermore, the (meth) acrylate monomer B is preferably an acrylate monomer having an ether bond and / or an alkyl group having 8 or more carbon atoms.

Preferred examples of the (meth) acrylate monomer B include long-chain alkyl (C8 or more) acrylate compounds, acrylate compounds having a polyethylene oxide or polypropylene oxide chain, and phenoxyethyl acrylate compounds.
Examples of the long-chain alkyl acrylate compound include 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, isooctyl acrylate, n-lauryl acrylate, n-tridecyl acrylate, n-cetyl acrylate, Examples thereof include n-stearyl acrylate, isomyristyl acrylate, and isostearyl acrylate.
Examples of the acrylate compound having a polyethylene oxide or polypropylene oxide chain include (poly) ethylene glycol monoacrylate, (poly) ethylene glycol acrylate methyl ester, (poly) ethylene glycol acrylate ethyl ester, (poly) ethylene glycol acrylate phenyl ester, (Poly) propylene glycol monoacrylate, (poly) propylene glycol monoacrylate phenyl ester, (poly) propylene glycol acrylate methyl ester, (poly) propylene glycol acrylate ethyl ester, methoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, ethoxydiethylene glycol Acrylate (Ethoxyeth Phenoxyethyl acrylate), methoxy polyethylene glycol acrylate.
Examples of the phenoxyethyl acrylate compound include phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy polyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and nonylphenol ethylene oxide adduct acrylate.
Examples of the (meth) acrylate monomer B include tetrahydrofurfuryl acrylate and 2- (N-butylcarbamoyloxy) ethyl acrylate (1,2-ethanediol 1-acrylate 2- (N-butylcarbamate)). Preferably mentioned.

  Among these, as the (meth) acrylate monomer B, phenoxyethyl acrylate, n-stearyl acrylate, isodecyl acrylate, ethoxyethoxyethyl acrylate, tetrahydrofurfuryl acrylate, n-lauryl acrylate, n-octyl acrylate, n-decyl acrylate , Isooctyl acrylate, n-tridecyl acrylate, and a monomer selected from the group consisting of 2- (N-butylcarbamoyloxy) ethyl acrylate, preferably phenoxyethyl acrylate and / or n-stearyl acrylate. More preferably. It is excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said aspect, and is excellent in a moldability.

The (meth) acrylate monomer B may be contained singly or in combination of two or more.
The content of the (meth) acrylate monomer B with respect to the total mass of the ink composition is preferably 1 to 70% by mass, more preferably 5 to 50% by mass, and 10 to 40% by mass. Is more preferable, and it is especially preferable that it is 14-30 mass%. It is excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said range, and is excellent in a moldability.

<< Bifunctional (meth) acrylate oligomer C having a weight average molecular weight of 2,000 to 20,000 >>
The ink composition preferably contains a polyfunctional (meth) acrylate oligomer as a polyfunctional (meth) acrylate compound, and a bifunctional (meth) acrylate oligomer C having a weight average molecular weight of 2,000 to 20,000. It is more preferable to contain.
The (meth) acrylate oligomer C may have an acryloyloxy group or a methacryloyloxy group, but preferably has an acryloyloxy group.
The (meth) acrylate oligomer C is an oligomer having a total of two acryloyloxy groups and / or methacryloyloxy groups.
The weight average molecular weight (Mw) of the (meth) acrylate oligomer C is 2,000 or more and 20,000 or less, preferably 5,000 or more and 20,000 or less, and 10,000 or more and 20,000 or less. It is more preferable. It is more excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said aspect.
As a method for measuring the weight average molecular weight of a resin such as a (meth) acrylate oligomer in the present invention, gel permeation chromatography (GPC) analysis is performed and measured.
More specifically, as GPC measurement conditions, HLC-8220 GPC manufactured by Tosoh Corporation is used, and three TSK gel SuperAWM-Hs are connected and used as a column, and N-methylpyrrolidone (10 mM LiBr) is used. Measure with a solvent at a flow rate of 0.5 mL / min. The sample concentration is 0.1% by mass, the injection volume is 60 μL, and the measurement temperature is 40 ° C. An RI detector (differential refractometer) is used as the detector.

The Young's modulus at 25 ° C. of the (meth) acrylate oligomer C is preferably 1 to 100 MPa, more preferably 2 to 80 MPa, further preferably 3 to 50 MPa, and preferably 10 to 30 MPa. Particularly preferred. It is more excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said range.
The Young's modulus at 25 ° C. of the (meth) acrylate oligomer C in the present invention is the Young's modulus at 25 ° C. of the homopolymer (monopolymer) of the (meth) acrylate oligomer C.
In the present invention, the Young's modulus at 25 ° C. is measured by the following method.
A liquid in which 2% by mass of Irgacure 819 (manufactured by BASF), 2% by mass of Irgacure 184 (manufactured by BASF), and 96% by mass of the oligomer to be measured was formed with a bar coater to form a coating film of 100 μm, and ultraviolet (UV) exposure Cured with a machine. At this time, the cured film was cured to such an extent that the influence of the degree of polymerization of the cured film was negligible. The cured film is cut into a 15 mm × 50 mm strip and the Young's modulus is measured with a tensile tester (Autograph AGS-X 5KN, manufactured by Shimadzu Corporation). The value of Young's modulus is measured at the 1% elongation. Moreover, in the test, it was pulled in the long axis direction, and the upper and lower portions of about 10 mm were gripped with a clamp.

The (meth) acrylate oligomer C is not particularly limited as long as it is an oligomer having Mw of 2,000 to 20,000 having a total of two acryloyloxy groups and / or methacryloyloxy groups. Oligomer, propylene oligomer butene oligomer, etc.), vinyl (styrene oligomer, vinyl alcohol oligomer, vinyl pyrrolidone oligomer, acrylic resin oligomer, etc.), diene (butadiene oligomer, chloroprene rubber, pentadiene oligomer, etc.), ring-opening polymerization system (di-) , Tri-, tetraethylene glycol, polyethylene glycol, polyethylimine, etc.), polyaddition system (oligoester (meth) acrylate, polyamide oligomer, polyisocyanate oligomer), addition If the oligomer can be exemplified (phenol resin, amino resin, xylene resin, ketone resin, etc.) and the like.
Among these, a urethane (meth) acrylate oligomer, a polyester (meth) acrylate oligomer, or an epoxy (meth) acrylate oligomer is preferable, and a urethane (meth) acrylate oligomer is more preferable.
As the urethane (meth) acrylate oligomer, polyester (meth) acrylate oligomer, and epoxy (meth) acrylate oligomer, an oligomer handbook (supervised by Junji Furukawa, Chemical Industries Daily, Inc.) can be referred to.
Examples of the (meth) acrylate oligomer C include Shin-Nakamura Chemical Co., Ltd., Sartomer, Daicel Cytec Co., Ltd., Rahn A. G. Those that are commercially available from companies and the like and that meet the above conditions can be used.

The (meth) acrylate oligomer C may be contained singly or in combination of two or more.
The content of the (meth) acrylate oligomer C with respect to the total mass of the ink composition is preferably 1 to 30% by mass, more preferably 5 to 25% by mass, and 10 to 20% by mass. Is more preferable, and 12 to 18% by mass is particularly preferable. It is more excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said range.
The proportion of the (meth) acrylate oligomer C in the polyfunctional (meth) acrylate compound in the ink composition is preferably 50% by mass or more based on the total mass of the polyfunctional (meth) acrylate compound, 80 More preferably, it is 90 mass% or more, It is more preferable that it is 95 mass% or more. It is more excellent in the softness and tensile strength of the obtained three-dimensional structure as it is the said range.

The ink composition may contain other polymerizable compounds other than (meth) acrylate monomer A, (meth) acrylate monomer B, and (meth) acrylate oligomer C.
Other polymerizable compounds include N-vinyl compounds, vinyl ether compounds, monofunctional acrylate compounds that do not fall under (meth) acrylate monomer A and (meth) acrylate monomer B, bifunctional or higher (meta) having a molecular weight of less than 2,000 Mw. ) Acrylate compounds and the like.
In addition, when it contains monomers other than (meth) acrylate monomer A, (meth) acrylate monomer B, and (meth) acrylate oligomer C, the content relative to the total mass of the ink composition is the content of (meth) acrylate monomer A. The content of (meth) acrylate monomer A, the content of (meth) acrylate monomer B, and the mass content of (meth) acrylate oligomer C are more preferably less.

-Colorant-
The ink composition preferably contains substantially no colorant other than white. In the method for forming a three-dimensional structure of the present invention, the yellow coloration of the obtained three-dimensional structure is small, and since the fingerprint trace residue when the obtained three-dimensional structure is touched with a hand is small, the yellow color is particularly high. The effect of the present invention can be particularly exerted in the case of using the ink composition that does not substantially contain a colorant other than white, in which coloring and the fingerprint trace residue appear remarkably.
The ink composition preferably contains a white colorant or substantially does not contain a colorant, and contains a white inorganic pigment or substantially no colorant. preferable.
When the white colorant is contained, the ink composition is a white ink composition. When the colorant is not substantially contained, the ink composition is a clear (transparent) ink composition.
There is no restriction | limiting in particular in the white colorant which can be used here, According to a use, well-known various white colorants can be selected suitably and can be used. Among them, the white colorant is preferably an inorganic pigment from the viewpoint of excellent light resistance.
The white inorganic pigment preferably used in the present invention will be described.
Examples of white inorganic pigments include commercially available pigment dispersions and surface-treated pigments such as those obtained by dispersing a pigment in an insoluble resin or the like using a dispersion medium, or those obtained by grafting a resin on the pigment surface. It can be used as long as the effects of the invention are not impaired.
As these inorganic pigments, for example, “Dictionary of Pigments” edited by Seijiro Ito (2000) Herbst, K.M. Examples include white inorganic pigments described in Hunger “Industrial Organic Pigments”, JP-A No. 2002-12607, JP-A No. 2002-188025, JP-A No. 2003-26978, and JP-A No. 2003-342503.

Specific examples of the white inorganic pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white). ), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) and the like can be used.
Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, and thus has a high hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersion of white inorganic pigments, for example, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. Can be used.
When dispersing the white inorganic pigment, a dispersant such as a surfactant can be added.
Moreover, when adding an inorganic pigment, it is also possible to use the synergist according to various inorganic pigments as a dispersion aid as needed. The dispersing aid is preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the inorganic pigment.

The white inorganic pigment may be directly added together with each component when preparing the ink composition. Further, in order to improve dispersibility, it may be added to a dispersion medium such as a solvent or a monomer in advance and uniformly dispersed or dissolved, and then blended.
As a dispersion medium for various components such as a white inorganic pigment, a solvent may be added, or the above polymerizable compound which is a low molecular weight component without solvent may be used as a dispersion medium. Is hardened by irradiation with actinic rays, and is preferably solvent-free. This is because if the solvent remains in the cured ink layer formed from the cured ink composition, the solvent resistance is deteriorated or the problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From this point of view, it is preferable to use a monomer as the dispersion medium, and in particular, to select a monomer having the lowest viscosity from the viewpoint of improving dispersion suitability and handling property of the ink composition.

The average particle diameter of the white inorganic pigment used here is preferably from 0.01 to 0.4 μm, and more preferably from 0.02 to 0.2 μm, since the finer the particle size, the better the color developability. The selection of the colorant, dispersant and dispersion medium, dispersion conditions and filtration conditions are set so that the maximum particle size is preferably 3 μm or less, more preferably 1 μm or less. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability, transparency, and curing sensitivity of the ink composition can be maintained. In the present invention, a uniform and stable dispersion can be obtained even when a particulate colorant is used by using the above-described dispersant having excellent dispersibility and stability.
The particle size of the white inorganic pigment can be measured by a known measurement method. Specifically, it can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method. In the present invention, a value obtained by measurement using a laser diffraction / scattering method is employed.

  When the ink composition contains a white colorant, the content of the white colorant with respect to the total mass of the ink composition is appropriately selected depending on the purpose of use, but from the viewpoint of colorability and storage stability, it is 0. 0.1 to 15% by mass is preferable, 0.5 to 10% by mass is more preferable, and 1 to 5% by mass is particularly preferable. Within the above range, the moldability is excellent, and the concealability in the obtained three-dimensional structure is excellent.

-Dispersant-
The ink composition may contain a dispersant. In particular, when a white inorganic pigment is used, a dispersant is preferably contained in order to stably disperse the white inorganic pigment in the ink composition. As the dispersant, a polymer dispersant is preferable. The “polymer dispersing agent” in the present invention means a dispersing agent having a weight average molecular weight of 1,000 or more.

Examples of the polymer dispersant include DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-166, and DISPERBYK-166. , DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (manufactured by BYK Chemie); EFKA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Efka Additive); Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (manufactured by Sannopco); Solsperse (SOLSPERSE) 3000 Various Solsperse dispersants (manufactured by Noveon) such as 5000, 9000, 12000, 13240, 13940, 17000, 22000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000; Adeka Pluronic L31, F38, L42, L44 , L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, -123 (manufactured by ADEKA Co., Ltd.), Ionette S-20 (manufactured by Sanyo Chemical Industries, Ltd.); Disparon KS-860, 873SN, 874 (polymer dispersant), # 2150 (aliphatic polycarboxylic acid), # 7004 (polyether ester type) (manufactured by Enomoto Kasei Co., Ltd.).
The content of the dispersant with respect to the total mass of the ink composition is appropriately selected depending on the purpose of use, but is preferably 0.01 to 15% by mass, and more preferably 0.05 to 5% by mass.

-Acrylic resin-
The ink composition preferably contains an acrylic resin. If it is the said aspect, the fingerprint trace residue at the time of touching the obtained three-dimensional structure with a hand will become smaller.
The acrylic resin is preferably a homopolymer or copolymer of a (meth) acrylate compound.
The acrylic resin is preferably an acrylic resin having a glass transition temperature of 50 ° C. to 120 ° C. and a weight average molecular weight of 5,000 to 200,000.
Furthermore, the acrylic resin preferably contains a methyl methacrylate homopolymer and / or copolymer, and more preferably contains an inactive methyl methacrylate homopolymer and / or copolymer.
The “inert methyl methacrylate homopolymer and / or copolymer” in the present invention means that the methyl methacrylate homopolymer and / or copolymer does not have a polymerizable functional group capable of further chain polymerization reaction. In addition, it means a polymer having no crosslinkable and / or crosslinkable functional group capable of further successive crosslinking reaction. That is, it refers to a methyl methacrylate homopolymer and / or copolymer in a state that does not substantially cause a polymerization reaction and a crosslinking reaction.

There is no restriction | limiting in particular as an inactive methylmethacrylate homopolymer, For example, what made methylmethacrylate a homopolymer by the well-known polymerization method, or what can be obtained as a commercially available homopolymer product is mentioned preferably.
Moreover, there is no restriction | limiting in particular as an inactive methylmethacrylate copolymer, For example, the thing which made methylmethacrylate and other polymeric compounds into the copolymer by the well-known polymerization method, or obtained as a commercially available copolymer product What can be preferably mentioned. The copolymer may be a random copolymer, a block copolymer, or a graft copolymer. As another polymerizable compound used for copolymerization, a (meth) acrylate compound is preferably exemplified. More preferably, it is a methacrylate compound.
An acrylic resin may be used individually by 1 type, or may use 2 or more types together.
The content of the acrylic resin is preferably 0.3 to 5% by mass, more preferably 0.5 to 4% by mass, and 1 to 3% by mass with respect to the total mass of the ink composition. It is particularly preferred. When it is within the above range, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched with a hand becomes smaller.

The weight average molecular weight of the acrylic resin is preferably 5,000 to 200,000, more preferably 8,000 to 150,000, still more preferably 10,000 to 100,000, It is particularly preferably 10,000 to 60,000, and most preferably 20,000 to 50,000. When the weight average molecular weight of the acrylic resin is within the above range, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller.
The weight average molecular weight of the acrylic resin is a polystyrene equivalent weight average molecular weight measured by a gel permeation chromatography (GPC) measurement method. Specific examples of the GPC measuring apparatus include HPLC LC-10AD manufactured by Shimadzu Corporation. In addition, for this GPC measurement, for example, Shodex GPC-KF-804 manufactured by Showa Denko KK is used as a column, and for example, tetrahydrofuran (THF) is used as an eluent, and the weight average molecular weight is the molecular weight of standard polystyrene. It is calculated by comparison with.

The glass transition temperature (Tg) of the acrylic resin is preferably 50 ° C. to 120 ° C., and more preferably 60 ° C. to 110 ° C. Within the above range, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched by hand becomes smaller.
In the present invention, the glass transition temperature of the resin is measured by differential scanning calorimetry (DSC measurement). Specifically, 10 mg of a sample is placed in a measurement pan, heated from −50 ° C. to 180 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then lowered to −50 ° C. at 10 ° C./min. Thereafter, the temperature is raised again from −50 ° C. to 180 ° C. at 10 ° C./min (2nd-run), and the temperature at which the baseline starts to be displaced from the low temperature side at 2nd-run is defined as the glass transition temperature (Tg).

  As the acrylic resin, a copolymer of methyl methacrylate and another polymerizable compound is preferably used. The other polymerizable compound is not particularly limited as long as the copolymer after polymerization is inactive, but a (meth) acrylate compound other than methyl methacrylate is more preferable, and a methacrylate compound other than methyl methacrylate is more preferable.

  As other copolymerizable monomers other than methyl methacrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, t-pentyl (meth) acrylate, neopentyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) Acrylate, 2-α-naphthoxyethyl (meth) acrylate, 2-β-naphthoxyethyl (meth) acrylate, 2-anthryl (meth) acrylate, 9-anthryl (meth) acrylate, 1-phenanthryl (meth) acryl Rate, 2-phenanthryl (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, p-nonylphenoxyethyl (meth) acrylate, p-nonylphenoxypolyethylene glycol (meth) acrylate, p-cumylphenoxyethylene glycol (meth) Acrylate, 2-furyl (meth) acrylate, 2-furfuryl (meth) acrylate, 2-thienyl (meth) acrylate, 2-thenyl (meth) acrylate, 1-pyrrolyl (meth) acrylate, 2-pyridyl (meth) acrylate, 2-quinolyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, cycloheptyl ( Acrylate), cyclooctyl (meth) acrylate, cyclodecyl (meth) acrylate, dicyclodecyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate, acryloylmorpholine N-phthalimidoethyl (meth) acrylate, pentamethylpiperidyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, 5- (meth) acryloyloxymethyl-5-ethyl-1,3-dioxacyclohexane, 2-ethylhexyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, carbitol (meth) acrylate, n-butyl (meth) acrylate, allyl ( Data) acrylate, glycidyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, oligoester (meth) acrylate. Among these, n-butyl (meth) acrylate is preferable, and n-butyl methacrylate is particularly preferable.

  The ratio of the monomer units derived from methyl methacrylate in the acrylic resin is preferably 10.0 to 90.0% by mass and 30.0 to 85.0% by mass with respect to the whole copolymer. More preferably. When it is within the above range, the moldability is excellent, and the fingerprint trace residue when the obtained three-dimensional structure is touched with a hand becomes smaller.

  Among the above-mentioned inert methyl methacrylate homopolymer and / or copolymer, the homopolymer is preferable in terms of convenience in that it is easy to select and use homopolymers of various molecular weights. The coalescence is preferable in that the physical properties of the copolymer such as solubility or compatibility can be changed by selecting the type of other (meth) acrylate monomers.

The acrylic resin can be obtained by a known method in the field. It may be synthesized from the corresponding (meth) acrylate compound by a polymerization reaction, or may be obtained from a commercial product.
Commercially available products of acrylic resins, particularly inert methyl methacrylate copolymers, include, for example, polymethyl methacrylate (molecular weight 10,000, catalog number 81497; molecular weight 20,000, catalog number 81498; molecular weight 50,000, manufactured by Aldrich. , Catalog number 81501), methyl methacrylate / n-butyl methacrylate copolymer (mass ratio 85/15, molecular weight 75,000; catalog number 474029), etc .; ELVACITE 2013 (methyl methacrylate / n-butyl methacrylate copolymer weight manufactured by Lucite International) Coalescence, mass ratio 36/64, molecular weight 37,000), 2021, 2614, 4025, 4026, 4028, etc .; Paraloid DM55, B66, etc. manufactured by Rohm and Haas ; Mitsubishi Rayon Co., Ltd. dialnal BR-113,115 etc. are mentioned.

-Surfactant-
The ink composition preferably contains a surfactant in order to impart stable ejection properties for a long time.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. Moreover, you may use a fluorine-type surfactant (for example, organic fluoro compound etc.) and silicone type surfactant (for example, polysiloxane compound etc.) as said surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

The polysiloxane compound is preferably a modified polysiloxane compound in which an organic group is introduced into a part of the methyl group of dimethylpolysiloxane. Examples of modification include polyether modification, methylstyrene modification, alcohol modification, alkyl modification, aralkyl modification, fatty acid ester modification, epoxy modification, amine modification, amino modification, mercapto modification, etc. is not. These modification methods may be used in combination. Of these, polyether-modified polysiloxane compounds are preferred from the viewpoint of improving ejection stability in inkjet.
Examples of the polyether-modified polysiloxane compound include, for example, SILWET L-7604, SILWET L-7607N, SILWET FZ-2104, SILWET FZ-2161 (manufactured by Nihon Unicar Co., Ltd.), BYK306, BYK307, BYK331, BYK333, BYK347. , BYK348 and the like (manufactured by BYK Chemie), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, Examples thereof include KF-6020, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).
Among these, as surfactant, a silicone type surfactant is mentioned preferably, A polysiloxane type surfactant is mentioned more preferably, A polydimethylsiloxane type surfactant is mentioned further more preferably.
The content of the surfactant in the ink composition of the present invention is appropriately selected depending on the purpose of use, but is preferably 0.0001 to 3% by mass with respect to the total mass of the ink composition.

-Sensitizer-
The ink composition, as a photopolymerization initiator, absorbs a specific actinic ray and promotes the decomposition of the polymerization initiator, and therefore functions as a sensitizer (hereinafter also simply referred to as “sensitizer”). However, it is preferable not to contain from a viewpoint of yellowing suppression.
Examples of the sensitizer include polynuclear aromatics (eg, pyrene, perylene, triphenylene, 2-ethyl-9,10-dimethoxyanthracene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, Rose Bengal etc.), cyanines (eg thiacarbocyanine, oxacarbocyanine etc.), merocyanines (eg merocyanine, carbomerocyanine etc.), thiazines (eg thionine, methylene blue, toluidine blue etc.), acridines (eg , Acridine orange, chloroflavin, acriflavine, etc.), anthraquinones (eg, anthraquinone, etc.), squaliums (eg, squalium), coumarins (eg, 7-diethylamino-4-methylcoumarin, etc.), thioxanthate Class (e.g., isopropyl thioxanthone), Chioku also sensitizers may be used either alone, or in combination of two or more.
The content of the sensitizer with respect to the total mass of the ink composition is preferably 0.1 to 5% by mass, and more preferably 0.5 to 3% by mass.

-Other ingredients-
The ink composition may contain other components in addition to the components described above, as necessary.
Other components include, for example, polymerization inhibitors, photopolymerization initiators other than specific photopolymerization initiators, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, solvents, and polymer compounds. , Basic compounds, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, rubber resins, waxes and the like. These are described in JP-A-2009-185186 and can also be used in the present invention.

The ink composition preferably contains a polymerization inhibitor from the viewpoint of improving storage stability.
In the heating step, the ink composition is heated in the range of 40 ° C. to 80 ° C., and the viscosity is lowered and discharged in the discharge step. Therefore, a polymerization inhibitor may be added to prevent clogging of the head due to thermal polymerization. preferable.
Examples of the polymerization inhibitor include nitroso polymerization inhibitors, hydroquinone, methoxyhydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL (HO-TEMPO), cuperon Al, hindered amine and the like.
Specific examples of the nitroso polymerization inhibitor preferably used in the present invention are shown below, but are not limited thereto.

Examples of commercially available nitroso polymerization inhibitors include FIRSTCURE ST-1 (manufactured by Chem First).
Examples of commercially available hindered amine polymerization inhibitors include TINUVIN292, TINUVIN770DF, TINUVIN765, and TINUVIN123.
Among them, as a polymerization inhibitor, cuperon Al (tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, FIRSTCURE ST-1), methoxyhydroquinone, and HO-TEMPO (4-hydroxy-2,2,6) , 6-tetramethylpiperidinyloxy) is preferably at least one compound selected from the group consisting of:

A polymerization inhibitor may be contained individually by 1 type, or may contain 2 or more types.
The content of the polymerization inhibitor with respect to the total mass of the ink composition is preferably 0.001 to 1.5 mass%, more preferably 0.01 to 1.0 mass%, and 0.05 to 0.8 mass%. Is more preferable. Within the above range, polymerization at the time of preparation and storage of the ink composition can be suppressed, and clogging of the ink jet nozzle can be prevented.

-Physical properties of ink composition-
The viscosity of the ink composition at 25 ° C. is preferably 20 to 150 mPa · s, and more preferably 40 to 100 mPa · s. It is excellent in discharge property and moldability as it is the said range.
The viscosity of the ink composition or the like in the present invention is a viscosity measured at a liquid temperature of 25 ° C. and measured with a digital viscometer (DV-I Prime, manufactured by Brookfield).
Further, the surface tension of the ink composition at 25 ° C. is preferably 20 to 40 mN / m, and more preferably 20 to 30 mN / m. It is excellent in discharge property and moldability as it is the said range.
The surface tension of the ink composition or the like in the present invention is a value measured using a surface tension meter (surface tension meter CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.) while maintaining the liquid temperature at 25 ° C.

<Ink composition for support material>
The ink composition for a support material that can be used in the present invention is not particularly limited, and a known ink composition for a support material can be used.
The support material ink composition includes a monofunctional acrylamide compound and / or a monofunctional acrylate compound having one or more hydroxy groups, polyethylene glycol and / or polypropylene glycol, and a photopolymerization initiator, The content of the bifunctional or higher acrylate compound with respect to the total mass of the ink composition for a support material is preferably 5% by mass or less.
The support material ink composition is preferably an actinic ray curable inkjet ink composition containing a monomer and a photopolymerization initiator.
In the 3D printing, the support material ink composition is suitably used as a support material for supporting the ink layer by being ejected around the position where the model material ink composition is ejected as necessary.
The ink composition for a support material that can be used in the present invention is preferably such that the support material obtained by curing can be easily removed, and the support material obtained by curing is a water-soluble cured product. And / or a hardened material that is smaller in hardness than the hardened model material and can be crushed.
The support material ink composition and the model material ink composition are preferably incompatible with each other. In the above embodiment, the moldability is excellent, and these two compositions can be simultaneously cured by irradiation with actinic rays.

  In the support material ink composition, the content of the bifunctional or higher acrylate compound with respect to the total mass of the support material ink composition is preferably 5% by mass or less, and more preferably 2% by mass or less. The content is more preferably 1% by mass or less, and particularly preferably no bifunctional or higher acrylate compound is contained. With the above aspect, the support material obtained is excellent in removability, and the occurrence of a failure of the three-dimensional structure can be suppressed when the obtained support material is removed.

-Monofunctional acrylamide compound and / or monofunctional acrylate compound having one or more hydroxy groups-
The ink composition for a support material preferably contains a monofunctional acrylamide compound and / or a monofunctional acrylate compound having one or more hydroxy groups. With the above aspect, the support material obtained is excellent in removability, and the occurrence of a failure of the three-dimensional structure can be suppressed when the obtained support material is removed.
The content of the monofunctional acrylamide compound and the monofunctional acrylate compound having one or more hydroxy groups with respect to the total mass of the ethylenically unsaturated compound in the support material ink composition is preferably 50% by mass or more. 80% by mass or more, more preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass, that is, the ethylenic property in the ink composition for a support material. Most preferably, the saturated compound contains only a monofunctional acrylamide compound and / or a monofunctional acrylate compound having one or more hydroxy groups. With the above aspect, the support material obtained is excellent in removability, and the occurrence of a failure of the three-dimensional structure can be suppressed when the obtained support material is removed.

Monofunctional acrylamide compounds include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide, N-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N- Hydroxyethylacrylamide, N-hydroxypropylacrylamide, N-hydroxybutylacrylamide, acryloylmorpholine, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-isopropylmethacrylamide, N-butyl Methacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N-hydroxyethylmethacrylamide, N- Mud propyl methacrylamide, N- hydroxy methacrylamide and methacryloyl morpholine and the like.
Among these, the monofunctional acrylamide compound preferably includes a compound selected from the group consisting of N-hydroxyethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, and N, N-dimethylacrylamide.

Monofunctional acrylate compounds having one or more hydroxy groups include hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, polyethylene glycol monoacrylate, methoxypolyethylene glycol monoacrylate, polypropylene glycol monoacrylate, methoxypolypropylene glycol monoacrylate Polyethylene glycol / polypropylene glycol block polymer monoacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, polyethylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, metho Shi polypropylene glycol monomethacrylate, mono methacrylate of polyethylene glycol / polypropylene glycol block polymer can be exemplified.
Among these, the monofunctional acrylate compound having one or more hydroxy groups includes a compound selected from the group consisting of polyethylene glycol monoacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate. It is preferable.

The monofunctional acrylamide compound may be contained singly or in combination of two or more, and the monofunctional acrylate compound having one or more hydroxy groups may be contained alone or in two kinds. The above may be contained, and a monofunctional acrylamide compound and a monofunctional acrylate compound having one or more hydroxy groups may be contained together.
The total content of the monofunctional acrylamide compound and the monofunctional acrylate compound having one or more hydroxy groups with respect to the total mass of the ink composition for a support material is preferably 1 to 95% by mass, and 3 to 50% by mass. More preferably, it is more preferably 5 to 30% by mass. Within the above range, it is possible to suppress the occurrence of a failure of the three-dimensional structure when removing the obtained support material.
Further, the total content of the monofunctional acrylamide compound and the monofunctional acrylate compound having one or more hydroxy groups with respect to the total mass of the ink composition for the support material is preferably smaller than the total content of polyethylene glycol and polypropylene glycol. .

-Polyethylene glycol and / or polypropylene glycol-
The ink composition for a support material preferably contains polyethylene glycol and / or polypropylene glycol, more preferably contains two or more kinds of polyethylene glycol and / or polypropylene glycol, and contains one or more kinds of polyethylene glycol and polypropylene glycol. More preferably, one or more of these are contained. With the above aspect, the support material obtained is excellent in removability, and the occurrence of a failure of the three-dimensional structure can be suppressed when the obtained support material is removed.
The number average molecular weight Mn of polyethylene glycol and polypropylene glycol is preferably 100 to 5,000, and more preferably 150 to 3,000. It is excellent in a moldability as it is the said aspect, and generation | occurrence | production of the failure of the three-dimensional structure at the time of removing the obtained support material can be suppressed.

Polyethylene glycol may be contained singly or in combination of two or more. Polypropylene glycol may be contained alone or in combination of two or more. Polyethylene glycol and polypropylene Glycol may be contained together.
The total content of polyethylene glycol and polypropylene glycol with respect to the total mass of the ink composition for a support material is preferably 10 to 98% by mass, more preferably 20 to 95% by mass, and 30 to 90% by mass. More preferably, it is particularly preferably 40 to 80% by mass. It is excellent in a moldability as it is the said range, and generation | occurrence | production of the failure of the three-dimensional structure at the time of removing the obtained support material can be suppressed.

-Photopolymerization initiator used in ink composition for support material-
The ink composition for a support material preferably contains a photopolymerization initiator.
The photopolymerization initiator is preferably a radical photopolymerization initiator.
Photopolymerization initiators include (a) aromatic ketones, (b) acylphosphine oxide compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thio compounds, (f) A hexaarylbiimidazole compound, (g) a ketoxime ester compound, (h) a borate compound, (i) an azinium compound, (j) a metallocene compound, (k) an active ester compound, (l) a compound having a carbon halogen bond, and (M) Alkylamine compounds and the like. These radical polymerization initiators may use the above compounds (a) to (m) alone or in combination. About the detail of the said polymerization initiator, what is described in Paragraph 0090-0116 of Unexamined-Japanese-Patent No. 2009-185186 can be illustrated, for example.
A photoinitiator may be used individually by 1 type, or may use 2 or more types together.
The ink composition for a support material preferably contains two or more photopolymerization initiators, more preferably 3 to 5 types, and still more preferably 3 types.

  Preferred examples of the photopolymerization initiator include an acyl phosphine oxide compound, an α-hydroxyketone compound and / or an α-aminoketone compound. Especially, as for the ink composition for support materials, it is especially preferable that the ink composition for support materials contains an acyl phosphine oxide compound and an alpha-hydroxy ketone compound.

As the acylphosphine oxide compound and the α-hydroxyketone compound, known compounds can be used. For example, those described above as the specific photopolymerization initiator are preferable.
As the α-aminoketone compound, known compounds can be used. Specifically, for example, 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1- [4- ( Hexyl) phenyl] -2-morpholinopropan-1-one, 2-ethyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), 2- (dimethylamino) -2-[(4- Preferred examples include methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone.

The photopolymerization initiator used in the support material ink composition preferably contains a water-soluble photopolymerization initiator.
For example, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one is a water-soluble photopolymerization initiator and can be preferably exemplified.

  The content of the photopolymerization initiator based on the total mass of the ink composition for a support material is preferably 1 to 20 mass%, more preferably 2 to 15 mass%, and 5 to 10 mass%. Is more preferable. It is excellent in sclerosis | hardenability as it is the said range, and generation | occurrence | production of the failure of the three-dimensional structure at the time of removing the obtained support material can be suppressed.

-Other ingredients-
The ink composition for a support material may contain other components in addition to the above components, as necessary.
Other components include, for example, polymerization inhibitors, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, solvents, water, polymer compounds, basic compounds, leveling additives, mats. Examples thereof include polyester resins, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like for adjusting the agent and film properties. These are described in JP-A-2009-185186 and can also be used in the present invention.
The ink composition for a support material may contain a monomer other than the monofunctional acrylamide compound and the monofunctional acrylate compound having one or more hydroxy groups.
When the monomer other than the monofunctional acrylamide compound and the monofunctional acrylate compound having one or more hydroxy groups is contained, the content of the ink composition for the support material with respect to the total mass is the monofunctional acrylamide compound and one or more. It is preferably less than the total mass content of the monofunctional acrylate compound having a hydroxy group, preferably 5% by mass or less, and preferably 2% by mass or less, based on the total amount of the ink composition for a support material. More preferably, it is more preferably 1% by mass or less, and particularly preferably not contained.

The ink composition for a support material used in the present invention preferably contains a polymerization inhibitor from the viewpoint of enhancing the storage stability.
Preferred examples of the polymerization inhibitor include those described above.
A polymerization inhibitor may be contained individually by 1 type, or may contain 2 or more types.
The mass content of the polymerization inhibitor with respect to the total amount of the ink composition for the support material is preferably 0.001 to 1.5% by mass, more preferably 0.01 to 1.0% by mass, and 0.05 to 0.8%. More preferred is mass%. When it is within the above range, polymerization at the time of preparation of the ink composition for the support material and storage can be suppressed, and clogging of the ink jet nozzle can be prevented.

-Physical properties of ink composition for support material-
The viscosity at 25 ° C. of the ink composition for a support material is preferably 20 to 150 mPa · s, and more preferably 40 to 100 mPa · s. It is excellent in discharge property and moldability as it is the said range.
Further, the surface tension at 25 ° C. of the ink composition for support material is preferably 20 to 40 mN / m, and more preferably 25 to 35 mN / m. It is excellent in discharge property and moldability as it is the said range.

  The method for producing the ink composition and the ink composition for support material is not particularly limited, and each component can be mixed and produced by a known method.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples.
In the following description, “part” represents “part by mass” and “%” represents “% by mass” unless otherwise specified.
Moreover, Tg of the monomer in the following is a glass transition temperature in the homopolymer of the monomer.

<Test 3D printer>
A transport stage and a light source of an ink jet printer KEGON (Afit Co., Ltd.) were modified and used as a 3D printer. The transport stage was provided with a mechanism (horizontal Z-axis automatic stage KS332-8N manufactured by Suruga Seiki Co., Ltd.) that can automatically raise and lower the height. The light source includes LED lamp wavelength peak 285 nm (manufactured by Nikkiso Co., Ltd.), wavelength peak 300 nm (manufactured by Nikkiso Co., Ltd.), wavelength peak 385 nm (LED lamp equipped with Accuracy 1600 LED manufactured by Fuji Film Co., Ltd.), and metal halide. Four types of lamps (Vzero II-85, manufactured by Integration Technology) can be equipped. Here, the head temperature was adjusted in the range of 50 ° C to 70 ° C.

<Preparation of pigment dispersion>
A composition other than the pigment described in Table 1 below is mixed and stirred with a mixer manufactured by SILVERSON (10-15 minutes, 2,000-3,000 rpm), and a uniform transparent liquid (dispersant diluent) is prepared. Obtained. A pigment was added to this transparent liquid (dispersant diluent), and further stirred with a mixer (10 to 20 minutes, 2,000 to 3,000 rpm) to obtain 500 parts of a uniform preliminary dispersion. Then, the dispersion process was implemented using the circulation type bead mill apparatus (SL-012C1) by a Dispermat company. Dispersion conditions were such that 200 parts of zirconia beads having a diameter of 0.65 mm were filled and the peripheral speed was 15 m / s. The dispersion time was 1 to 6 hours.

The detail of each component described in Table 1 is shown below.
TiO ₂ (titanium oxide, white pigment, KRONOS 2300, manufactured by KRONOS)
PB15: 4 (CI pigment blue 15: 4, cyan pigment, HELIOGEN BLUE D 7110 F, manufactured by BASF)
Mixed quinacridone (quinacridone-based mixed crystal pigment, magenta pigment, CINQUASIA MAGENTA L 4540, manufactured by BASF)
PY155 (CI Pigment Yellow 155, Yellow Pigment, INK JET YELLOW 4GC, manufactured by Clariant)
Carbon black (CAS No. 1333-86-4, black pigment, Mogul E, manufactured by Cabot)
Sol32000 (dispersant, SOLPERSE 32000, manufactured by Lubrizol)
Sol 41000 (dispersant, SOLPERSE 41000, manufactured by Lubrizol)
UV12 (polymerization inhibitor, FLORSTAB UV-12, manufactured by Kromachem)
PEA (2-phenoxyethyl acrylate, Tg: 5 ° C., molecular weight: 192, SR339C, manufactured by Sartomer)

<Production of model material>
The compositions listed in Tables 2 to 6 below were mixed and stirred with a mixer manufactured by SILVERSON (10 to 15 minutes, 2,000 to 3,000 rpm) to obtain a uniform liquid composition. This was used as a model material for Examples, Comparative Examples or Reference Examples.

(Examples 1 to 23 and Comparative Examples 1 to 11 (light source is fixed to an LED having a wavelength peak of 300 nm))
Support material (Stratasys support material) and model materials (inks T1 to T22, W1 to W4, C1, C2, M1, M2, Y1, Y2, K1, or K2) described in Tables 2 to 6 above A 3D printer (light source fixed to an LED having a wavelength peak of 300 nm) was filled, and the moldability, coloring, concealability (white only), fingerprint trace, and volume shrinkage were evaluated by the methods described below. Furthermore, the ink composition was filled in a glass bottle and stored at 60 ° C. for 4 weeks and at −15 ° C. for 2 weeks. Changes in liquid properties before and after storage were measured, and the ink stability was evaluated by the method described below.

<Moldability evaluation>
A rectangular parallelepiped having a length of 1 cm × 1 cm × 5 mm was prepared, and the angle of the vertex of the upper surface of the obtained rectangular parallelepiped was measured and evaluated according to the following evaluation criteria.
5 (excellent): All vertex angles are less than 90 ± 0.5 degrees 4 (good): The largest error from 90 degrees is 0.5 degree or more and less than 1 degree 3 (acceptable): most from 90 degrees Large error is 1 degree or more and less than 1.5 degree 2 (defect): The largest error from 90 degree is 1.5 degree or more and less than 2.0 degree 1 (very bad): The largest error from 90 degree 2.0 degrees or more

<Coloring (transparent)>
To prepare a plate sample having a thickness of 1 mm, was measured by FUJIFILM Corp. inkjet photo paper (Gasai) background, the sample hue _{^{(L 1, a * 1,}} b * 1), and, for photographic paper Hue (L ₂ , a ^* ₂ , b ^* ₂ ) was measured with Gretag SPM100-II, and ΔE = {(a ^* ₁ −a ^* ₂ ) ² + (b ^* ₁ −b ^* ₂ ) ² + and _(L 1 _-L ^{2) 2}} was evaluated by the evaluation criteria of ^1/2 to calculate the following.
5 (excellent): ΔE is less than 3 4 (good): ΔE is 3 or more and less than 6 3 (allowable): ΔE is 6 or more and less than 9 2 (defect): ΔE is 9 or more and less than 12 1 (very bad): ΔE is 12 or more

<Coloring (white and color)>
To prepare a plate sample having a thickness of 1 mm, was measured by FUJIFILM Corp. inkjet photo paper (Gasai) background, the sample hue _{^{(L 1, a * 1,}} b * 1), and, for photographic paper Hue (L ₂ , a ^* ₂ , b ^* ₂ ) was measured with Gretag SPM100-II, and ΔE = {(a ^* ₁ −a ^* ₂ ) ² + (b ^* ₁ −b ^* ₂ ) ² + and _(L 1 _-L ^{2) 2}} was evaluated by the evaluation criteria of ^1/2 to calculate the following.
5 (excellent): ΔE is less than 8 4 (good): ΔE is 8 or more and less than 10 3 (allowable): ΔE is 10 or more and less than 13 2 (defect): ΔE is 13 or more and less than 16 1 (very bad): ΔE is 16 or more

<Concealment (white only)>
A plate sample having a thickness of 1 mm was prepared, and the brightness of the sample (L ¹ ) measured with Fuji Photo Film's inkjet photo paper (color) as the background, and the brightness of the sample as measured against the blackboard ( L ² ) was measured with Gretag SPM100-II, and the concealment rate (%) = 100 × (L ² / L ¹ ) was calculated and evaluated according to the following evaluation criteria.
5 (excellent): concealment rate is 98% or more 4 (good): concealment rate is 96% or more and less than 98% 3 (allowable): concealment rate is 94% or more and less than 96% 2 (defect): concealment rate is 92% or more Less than 94% 1 (very poor): Concealment rate is less than 92%

<Fingerprint mark evaluation>
A cube with a length of 3 cm was prepared, and the evaluation was performed using a leather base material (Kappi CP830, YAMAPLUS Co., Ltd.) with a texture by simulating the fingerprint of a finger. The above leather base material was pressed against a surface of 3 cm × 3 cm for 1 minute under a load of 1 kg, and the sample surface after peeling it from the cube was visually observed and evaluated according to the following evaluation criteria. In addition, 12 hours after printing, environmental temperature was implemented at 35 degreeC, 30 degreeC, 20 degreeC, and 10 degreeC.
5 (excellent): no marks on the sample surface at 35 ° C, 30 ° C, 20 ° C, 10 ° C 4 (good): no marks on the sample surface at 30 ° C, 20 ° C, 10 ° C 3 (acceptable) at 35 ° C. 3 (acceptable): no marks on the sample surface at 20 ° C. and 10 ° C., but remains at 35 ° C. and 30 ° C. 2 (poor): no marks on the sample surface at 10 ° C. Not, but remains at 35 ° C, 30 ° C, and 20 ° C 1 (very bad): marks remain at all temperatures

<Shrinkage rate evaluation>
The density of the model material liquid and the three-dimensional structure was measured using a dry automatic densimeter (Acupic II 1340 series, manufactured by Shimadzu Corporation). The density of the liquid was measured with a liquid sample of about 1 g, and the density of the three-dimensional structure was measured with a sample molded into a cube having a side of 10 mm. Based on these density differences, the following evaluation criteria were used.
5 (excellent): density difference is less than 3% 4 (good): density difference is 3% or more and less than 6% 3 (allowable): density difference is 6% or more and less than 9% 2 (defect): density difference is 9% or more Less than 12% 1 (very bad): density difference is 12% or more

<Ink stability>
Two glass bottles are filled with the ink composition, one glass bottle is stored at 60 ° C. for 4 weeks, the other glass bottle is stored at −15 ° C. for 2 weeks, and the 60 ° C. storage sample measures the change in viscosity before and after storage. Moreover, the -15 degreeC sample investigated the presence or absence of the deposit, and evaluated it by the method as described below.
5 (Excellent): Viscosity change is less than 5% and no precipitate 4 (Good): Viscosity change is 5% or more and less than 10% and no precipitate 3 (Acceptable): Viscosity change is 10% or more and 15% Less than and no precipitate 2 (defect): Viscosity change is 15% or more and no precipitate 1 (very poor): Viscosity change is 15% or more regardless of the presence or absence of precipitates and / or precipitates Yes

The details of each compound and abbreviations described in Tables 2 to 6 and Table 7 described later are as follows.
IBOA (isobornyl acrylate, monofunctional acrylate compound, Tg: 94 ° C., molecular weight: 208, SR506D, manufactured by Sartomer)
HDDA (1,6-hexanediol diacrylate, Tg: 43 ° C., molecular weight: 226, SR238, manufactured by Sartomer)
PEG200DA (polyethylene glycol (molecular weight about 200) diacrylate, bifunctional, SR259, manufactured by Sartomer)
FA512 (dicyclopentenyloxyethyl acrylate, monofunctional acrylate compound, funcryl FA-512, manufactured by Hitachi Chemical Co., Ltd.)
SR217 (t-butylcyclohexyl acrylate, monofunctional acrylate compound, manufactured by Sartomer)
EOEOEA (2- (2-ethoxyethoxy) ethyl acrylate, monofunctional acrylate compound, SR256, manufactured by Sartomer)
CN9001 (bifunctional urethane acrylate, manufactured by Sartomer)
Ebecryl 270 (bifunctional urethane acrylate, Mw: 1,500, glass transition temperature: −27 ° C., acrylate number: 750 g / valence, manufactured by Daicel Cytec Co., Ltd.,
Irg184 (1-hydroxycyclohexyl phenyl ketone, photopolymerization initiator, IRGACURE184, manufactured by BASF)
Irg2959 (1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one, photopolymerization initiator, IRGACURE2959, manufactured by BASF)
KIP160 (a polyfunctional photopolymerization initiator having two or more 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one structures, ESACURE KIP160, manufactured by Lamberti)
Irg127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one, photopolymerization initiator, IRGACURE127, manufactured by BASF)
Dar 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one, photopolymerization initiator, DAROCUR 1173, manufactured by BASF)
Irg819 (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, photopolymerization initiator, IRGACURE819, manufactured by BASF)
BR113 (copolymer of methyl methacrylate and butyl methacrylate, Mw: 30,000, Tg: 75 ° C., Dialnal BR-113, manufactured by Mitsubishi Rayon Co., Ltd.)
Elvacite 2927 (acrylic resin, Mw: 19,000, Tg 45 ° C., manufactured by Lucite International)
Dianal MB-7833 (acrylic resin, Mw: 3,000, Tg 60 ° C., manufactured by Dianal)
BYK307 (polydimethylsiloxane surfactant, BYK-307, manufactured by BYK Chemie)
UV1 (polymerization inhibitor, FLORSTAB UV-1, manufactured by Kromachem)
SpeedBright OB-184 (2,5-bis (5-tert-butyl-2-benzoxazolyl) thiophene, manufactured by Lambson)

(Example 24 (light source is changed to an LED having a wavelength peak of 280 nm, 300 nm, or 385 nm, or a metal halide lamp))
Fill the support material (Stratasys support material) and the model material (ink T1) shown in Table 7 into the 3D printer (the light source is changed to an LED having a wavelength peak of 280 nm, 300 nm or 385 nm, or a metal halide lamp). The moldability and fingerprint trace were evaluated by the methods described below. Table 7 shows the evaluation results.

<Moldability evaluation>
A rectangular parallelepiped having a length of 1 cm × 1 cm × 5 mm was prepared, and the angle of the vertex of the upper surface of the obtained rectangular parallelepiped was measured and evaluated according to the following evaluation criteria.
5 (excellent): All vertex angles are less than 90 ± 0.5 degrees 4 (good): The largest error from 90 degrees is 0.5 degree or more and less than 1 degree 3 (acceptable): most from 90 degrees Large error is 1 degree or more and less than 1.5 degree 2 (defect): The largest error from 90 degree is 1.5 degree or more and less than 2.0 degree 1 (very bad): The largest error from 90 degree 2.0 degrees or more

<Fingerprint mark evaluation>
A cube with a length of 3 cm was prepared, and the evaluation was performed using a leather base material (Kappi CP830, YAMAPLUS Co., Ltd.) with a texture by simulating the fingerprint of a finger. The above leather base material was pressed against a surface of 3 cm × 3 cm for 1 minute under a load of 1 kg, and the sample surface after peeling it from the cube was visually observed and evaluated according to the following evaluation criteria. The environmental temperature was 35 ° C, 30 ° C, 20 ° C, and 10 ° C.
5 (excellent): no traces of wrinkles on the sample surface at 35 ° C., 30 ° C., 20 ° C. and 10 ° C. 4 (good): imprints of wrinkles on the sample surface at 30 ° C., 20 ° C. and 10 ° C. Does not remain, but remains at 35 ° C. 3 (acceptable): at 20 ° C. and 10 ° C., no traces of wrinkles remain on the sample surface, but remains at 35 ° C. and 30 ° C. 2 (poor): at 10 ° C. No marks are left on the sample surface, but remain at 35 ° C, 30 ° C, and 20 ° C. 1 (very bad): Marks remain at all temperatures.

<Immediately after fingerprint trace evaluation>
A cube with a length of 3 cm was prepared, and the evaluation was performed using a leather base material (Kappi CP830, YAMAPLUS Co., Ltd.) with a texture by simulating the fingerprint of a finger. The above leather base material was pressed against a surface of 3 cm × 3 cm for 1 minute under a load of 1 kg, and the sample surface after peeling it from the cube was visually observed and evaluated according to the following evaluation criteria. The environmental temperature was 20 ° C. within 1 minute immediately after printing.
3 (excellent): no traces of wrinkles remain 2 (acceptable): wrinkle marks remain immediately after the leather is peeled off, but cannot be seen within 10 minutes 1 (defect): wrinkle marks 10 minutes after the leather is peeled off Remains

  In addition, the description of 280 nm, 300 nm, 385 nm, and meta harassment in parentheses in the moldability and fingerprint trace evaluation column of Table 7 uses an LED having a wavelength peak of 280 nm, 300 nm, or 385 nm, or a metal halide lamp as a light source, respectively. Indicates that it has been done.

Claims (11)

A heating step of heating the ink composition to a range of 40 ° C to 80 ° C;
An ejection step of ejecting the heated ink composition with an inkjet head and forming an ink layer based on cross-sectional information of the three-dimensional structure; and
A curing step of curing the ink layer with actinic rays,
The ink composition contains at least one (meth) acrylate compound;
The content of the monofunctional (meth) acrylate compound with respect to 100 parts by mass of the total (meth) acrylate compound in the ink composition is 50 to 95 parts by mass,
The ink composition comprises 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2- Methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one, and 4-20 mass% of 1 or more types of photoinitiators selected from the group which consists of the compound which multifunctionalized any one kind of initiator with respect to the total mass of an ink composition,
The said hardening process uses the LED light source which has a peak between wavelengths 275-310 nm, The formation method of the three-dimensional structure characterized by the above-mentioned.   The method for forming a three-dimensional structure according to claim 1, wherein the content of the photopolymerization initiator in the ink composition is 6 to 12% by mass with respect to the total mass of the ink composition.   The ink composition contains 1 to 3% by mass of an acrylic resin having a glass transition temperature of 50 ° C. to 120 ° C. and a weight average molecular weight of 5,000 to 200,000 based on the total mass of the ink composition. The method for forming a three-dimensional structure according to claim 1 or 2.   The method for forming a three-dimensional structure according to any one of claims 1 to 3, wherein the ink composition does not substantially contain a colorant.   The method for forming a three-dimensional structure according to any one of claims 1 to 3, wherein the ink composition contains titanium oxide as a white colorant.   The method for forming a three-dimensional structure according to claim 5, wherein a content of titanium oxide in the ink composition is 1 to 5 mass% with respect to a total mass of the ink composition.   The method for forming a three-dimensional structure according to any one of claims 1 to 6, wherein the ink composition contains two or more types of the photopolymerization initiator.   The method for forming a three-dimensional structure according to claim 7, wherein the ink composition contains two or three kinds of the photopolymerization initiator.   The method for forming a three-dimensional structure according to claim 3, wherein the acrylic resin is a methyl methacrylate homopolymer and / or a copolymer.   The method for forming a three-dimensional structure according to claim 9, wherein the acrylic resin is a methyl methacrylate copolymer.   The method for forming a three-dimensional structure according to any one of claims 1 to 10, wherein the ink composition contains a bifunctional (meth) acrylate oligomer having a weight average molecular weight of 2,000 or more and 20,000 or less. .