JP2018083370A - Shaping-particle manufacturing method, shaping particle, powder, and three-dimensional object manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a shaping particle suited for a structure of a support part easily removable by a water-containing liquid and capable of suppressing deterioration of shape accuracy of a three-dimensional object.SOLUTION: The present invention relates to a method of manufacturing a shaping particle 5, the method comprising in the order of description: a mixing step for mixing a powder containing a first particle 1 containing a water-soluble material and a powder containing a second particle 2 containing a material less soluble in water than the water-soluble material contained in the first particle 1 to obtain a mixed powder; a drying step for drying until the water content of the mixed powder becomes less than 1.0 mass%; and a compositing step for compositing the first particle 1 and the second particle 2 to form a shell 4, which contains the largest amount of the material less soluble in water than the water-soluble material, on the surface of the first particle 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a manufacturing method of modeling particles, modeling particles, powder, and a manufacturing method of a three-dimensional object.

In recent years, an additive manufacturing method that manufactures a three-dimensional object by laminating modeling materials based on cross-sectional data of a three-dimensional object (modeling object) to be produced has attracted attention.
In the additive manufacturing method, when producing a three-dimensional object having a complicated structure such as a structure having an overhang part or a structure in which a plurality of isolated parts are combined, there is no structure part constituting the three-dimensional object. The structure may be stacked on top of the area. In such a case, a support part that supports the structure part is provided below the structure part in the direction of gravity. That is, a support part is formed in the part which becomes the space | gap of a solid object as needed in the process of modeling by the additive manufacturing method. The support portion thus formed is finally removed.
Patent Document 1 describes a material for forming a structure portion and a method for manufacturing a three-dimensional object using a support material that is a material for forming a support portion. The support material is a water-soluble material such as a water-soluble carbohydrate. It is described that it consists of. Thereby, a support part can be selectively dissolved and removed by immersing a modeling thing which has a structure part and a support part in water. Thus, it is preferable from a viewpoint of the ease of removal of a support part, environmental impact, etc. that a support part can be removed by making it contact with water.

JP2015-180537A

In Patent Document 1, a particulate (powdered) support material is used, and methods such as a mechanical pulverization method and a spray drying method are described as methods for producing the particulate support material. Many water-soluble materials such as water-soluble carbohydrates that are used as the material constituting the support material are highly hygroscopic, and the support material finally obtained by absorbing moisture in the atmosphere during the manufacturing process. The water content may increase. In addition, the moisture content may be increased by absorbing moisture in the atmosphere after production.
Since the particulate support material having a high water content has low fluidity, there are cases where the shape accuracy of the three-dimensional object obtained when the three-dimensional object is produced using this is reduced. In addition, when a three-dimensional object is manufactured using a support material having a high moisture content, the water contained in the support material is vaporized during the manufacturing process of the three-dimensional object, thereby reducing the shape accuracy of the three-dimensional object obtained. There was a thing. As described above, when a three-dimensional object is manufactured using a particulate support material containing a large amount of moisture, there is a problem in that problems such as a reduction in the shape accuracy of the three-dimensional object obtained occur.
Therefore, in view of the above-described problems, the present invention provides a method for producing shaped particles that is suitable for the configuration of a support part that can be easily removed by a liquid containing water and that can suppress a decrease in the shape accuracy of a three-dimensional object. Objective.

The method for producing shaped particles of the present invention
A mixed powder obtained by mixing a powder containing first particles containing a water-soluble material and a powder containing second particles containing a material having a lower solubility in water than the water-soluble material. A mixing step to obtain,
A drying step of drying until the water content of the mixed powder is less than 1.0% by mass;
A composite step of combining the first particles and the second particles, and forming a shell containing the most material having a lower solubility in water than the water-soluble material on the surface of the first particles;
In this order.

  ADVANTAGE OF THE INVENTION According to this invention, it is suitable for the structure of the support part which can be easily removed with the liquid containing water, and the modeling particle which can suppress the fall of the shape accuracy of a solid object can be provided.

It is a schematic diagram explaining the manufacturing method of the modeling particle | grains which concern on this embodiment. It is a schematic block diagram of the modeling apparatus of the solid object using an electrophotographic system. 6 is a graph showing mass reduction during heating in Example 1 and Comparative Example 1.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below. Further, in the present invention, the scope of the present invention also includes those in which the embodiments described below are appropriately modified and improved based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. include.

<Modeling particles>
First, the modeling particle which concerns on this embodiment manufactured with the manufacturing method of the modeling particle which concerns on this embodiment is demonstrated. In the present specification, the “modeling particle” refers to a particulate modeling material used when a three-dimensional object is manufactured. The modeling material is classified into a structural material that constitutes a target three-dimensional object and a support material that supports the lamination of the structural materials. The support portion made of the support material is a portion that supports the structural material laminated on the region where no structural material exists, and is a portion that is finally removed. That is, the “shaped particles” are classified into “structural material particles” that are particulate structural materials and “support material particles” that are particulate support materials. In the present specification, “powder” means an aggregate of particles. Hereinafter, the aggregate of “structural material particles” may be referred to as “structural material powder”, and the aggregate of “support material particles” may be referred to as “support material powder”.

  When a water-insoluble material is used as the structural material, if the material that can be removed by water is used as the support material that constitutes the support part, it is possible to selectively remove the support part from the layered product by water. Become. If the support part can be removed using water, the cost for removing the support part can be kept low because water is easily available. Furthermore, since water is highly safe and has a low load on workers and the environment, it is very preferable to use water for removing the support portion. Here, “water-insoluble” means a property having a solubility in water of less than 0.1, and “water-soluble” means a property having a solubility in water of 0.1 or more. The “solubility in water” is a numerical value representing the mass dissolved in 100 g of pure water having a water temperature of 20 ° C. at 1 atm in grams.

  In consideration of removability by water, the support part is preferably composed of a water-soluble material having high solubility in water. However, when a particle made of a water-soluble material having a high solubility in water is exposed to an atmosphere with high humidity, it absorbs moisture in the atmosphere and increases the viscosity of the particle surface. The modeling particles are accommodated in a powder state in the material container of the apparatus used for modeling. If such particles are contained in the powder, the fluidity is remarkably reduced due to aggregation due to humidity. . Powders with significantly reduced fluidity can lead to malfunctions in the modeling process and the accuracy of the resulting modeling object, so the humidity of the powder storage environment and usage environment must be strictly controlled. In addition, the convenience is inferior and the manufacturing cost increases.

  Then, the modeling particle | grains concerning this embodiment have the cross-sectional structure shown to Fig.1 (a). That is, the modeling particle 5 includes the core 3 and the shell 4 that covers at least a part of the surface of the core 3. Further, the core 3 contains the most water-soluble material, and the solubility of the material contained most in the shell 4 in water is smaller than the solubility in water of the water-soluble material contained in the core 3, and the plurality of shaped particles 5 The water content of the powder consisting of is less than 1.0% by mass. In addition, the solubility of the core 3 and the shell 4 can be calculated | required if each part is isolate | separated from particle | grains and each solubility is measured.

The shaped particles having such a configuration can be obtained by applying thermal energy or thermal energy and pressure under appropriate conditions according to the coverage of the shell 4 on the surface of the core 3 and the material of the core 3 and the shell 4. The material can be exposed to the particle surface. For example, the shell structure is destroyed by heating to the softening temperature of the core 3 or the modeling particle, or by heating at the same time as the softening temperature of the core 3 or the modeling particle, and the material of the core 3 is exposed to the surface. Can be made. Here, the softening temperature in this specification refers to a temperature at which the loss elastic modulus becomes 10 ⁸ Pa or less when dynamic viscoelasticity is measured. Alternatively, a solution that selectively dissolves the material of the shell 4 is sprayed on the modeling particles, and the material of the shell 4 is unevenly distributed on the particle surface by utilizing the surface tension of the droplet formed on the particle surface, thereby exposing the material of the core 3. It is also possible to make it.

  Thus, since the modeling particle | grains which concern on this embodiment form the material (shell 4) whose solubility with respect to water is lower than the water-soluble material contained in the core 3 in the surface, it is water | moisture content in a powder state. Even in a large amount of atmosphere, aggregation due to moisture absorption is suppressed, and a decrease in fluidity is suppressed. Therefore, the state of the powder suitable for the additive manufacturing method can be maintained without particularly managing the humidity. Then, in the manufacturing process of the three-dimensional object, the material of the core 3 extruded from the inside of the plurality of modeling particles is fused to form a three-dimensional object by heating and pressurizing the core 3 or the molding particle to a softening temperature or higher. be able to. Alternatively, in the manufacturing process of the three-dimensional object, the material of the core 3 is exposed by spraying a solution that selectively dissolves the shell 4 and then dried, and a plurality of particles are bound by the material of the shell 4. A solid object can also be formed.

  Since the core 3 contains the most water-soluble material, the water-soluble material can be dissolved by bringing it into contact with water, and the shape of the model can be collapsed. From this property, the shaped particles according to the present embodiment are suitable as support material particles. When the modeling particle which concerns on this embodiment is used as support material particle | grains, it can remove easily from a structure part by making a support part contact water after modeling. Therefore, the shape of the structure part is not impaired by the support part removing step, and a highly accurate three-dimensional object can be obtained. “Easy” means that the time required for removal is short, or at least one of special work and environment is not required for removal.

  In order to secure the removability of the support part, it is desirable that the support part has a structure in which the material of the shell 4 is scattered in the three-dimensional network structure made of the water-soluble material of the core 3. . For this purpose, the core 3 needs to contain a water-soluble material that can only form a three-dimensional network structure made of the water-soluble material. Therefore, the volume ratio of the shaped particles to the entire core 3 particles is preferably 50% or more, and more preferably 70% or more. Alternatively, depending on the specific gravity of the material contained in the core 3 or the shell 4, the mass ratio of the water-soluble material contained in the core 3 to the entire core 3 is preferably 50% or more, and preferably 70% or more. More preferred.

  The water-soluble material contained in the core 3 may be one type or a plurality of types. When multiple types of water-soluble materials are included, the total amount of these multiple types of water-soluble materials may be considered as the water-soluble material contained in the core 3. Therefore, what is necessary is just to calculate the volume ratio or mass ratio of the water-soluble material with respect to the whole core 3 using the total amount of a plurality of types of water-soluble materials. The “type” of the water-soluble material here is determined by the chemical structure, and when the chemical structure is different, it is expressed that the type is different. Further, when there are a plurality of types of water-soluble materials contained in the core 3, the solubility in water of the material most contained in the shell 4 is “smaller than the solubility in water of the water-soluble material contained in the core”. It means that the solubility in water of any water-soluble material contained in is smaller.

  The water-soluble material contained in the core 3 is not particularly limited as long as it has water solubility, but is preferably a material having a solubility in water of more than 1, more preferably a material of more than 5, and even more preferably 10 or more. As the water-soluble material, a simple substance, a compound, a complex of these, or the like can be used. Specifically, water-soluble inorganic materials, water-soluble carbohydrates, polyalkylene oxides, and polyvinyl alcohol (PVA) are preferable. Examples of water-soluble carbohydrates include saccharides such as monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides, and sugar alcohols, and water-soluble dietary fibers. Specific examples of water-soluble dietary fiber include polydextrose and inulin. Specific examples of carbohydrates include sucrose, lactose, maltose, trehalose, melezitose, stachyose, maltotetraose, lactitol, mannitol, and derivatives thereof. Etc. A specific example of the polyalkylene oxide is polyethylene glycol (PEG). Among these, saccharides are desirable from the viewpoint of high water solubility, availability, and biological safety, and maltotetraose and lactitol are particularly preferable.

  The core may contain a water-insoluble material. The water-insoluble material is preferably a material that adjusts the characteristics of modeling particles according to the layered modeling method, but is not limited thereto.

  For example, in the case of particles used for a modeling method that is laminated by heating and pressing, a viscoelasticity adjusting material for adjusting the viscoelasticity at the time of heating and pressing may be added. It is preferable that the viscoelasticity adjusting material has a size smaller than the particle size of the modeling particles.

  Further, as the adjusting material for increasing the viscoelasticity, a fiber material is preferable in order to prevent the movement of the main component of the core 3 during the viscous flow. Examples of the fiber material include water-insoluble fibers (hereinafter referred to as nanofibers) having a nano-sized diameter or length, and cellulose nanofibers can be suitably used. This is because by containing nanofibers in the main component of the core 3, a matrix made of nanofibers can be formed inside the core 3, and it becomes easy to increase the viscoelasticity of the core 3. Further, as an adjusting material for lowering viscoelasticity, it is possible to use a plasticizer that improves the movement of the main component of the core 3 during viscous flow.

  In the case of particles used for modeling using an electrophotographic process, a charge control agent may be added to control chargeability. The modeling particles may contain the charge control agent alone or in combination of two or more.

  As the charge control agent for controlling the particles to be negatively charged, organometallic compounds and chelate compounds are effective. Specific examples include a monoazo metal compound, an acetylacetone metal compound, an aromatic oxycarboxylic acid, an aromatic dicarboxylic acid, an oxycarboxylic acid, and a dicarboxylic acid-based metal compound. In addition, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol are also preferable. Furthermore, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, resin charge control agents, and the like can also be used.

  Examples of charge control agents for controlling particles to be positively charged include nigrosine-modified products of nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetra Quaternary ammonium salts such as fluoroborate and these lake pigments can be used. Also preferred are triphenylmethane dyes, metal salts of these lake pigment higher fatty acids, and resin charge control agents. As the rake agent, phosphotungstic acid, phosphomolybthenic acid, phosphotungstomolybthenic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide can be used.

  The material most contained in the shell 4 is not limited as long as the solubility in water is smaller than the solubility in water of the water-soluble material contained in the core 3, but a material having a solubility in water of less than 10 is preferable, and a material less than 5 is preferable. More preferably, it is more preferably 1 or less.

  Examples of the material most contained in the shell 4 include organic substances typified by organic compounds and polymer compounds, inorganic substances typified by metals and ceramics, and organic / inorganic composite materials containing organic substances and inorganic substances. However, it is not limited to these materials.

  Specifically, for organic substances, resin compounds such as acrylic resins, vinyl resins, polyester resins, epoxy resins, and urethane resins, ester compounds such as glycerin fatty acid esters, sucrose fatty acid esters, and sorbitan fatty acid esters A part of cellulose derivatives such as ethyl cellulose can be preferably used. Among these, a resin substance is preferable, and styrene-acrylic copolymer, polymethyl methacrylate, and polystyrene are particularly preferable.

  Moreover, if it is an inorganic substance, inorganic oxides, such as a silicon oxide, a titanium oxide, and an alumina, can be used conveniently. Further, those having a structure in which fluorine is directly bonded to these inorganic oxides are also preferably used.

  As the organic / inorganic composite material, a compound having a siloxane bond as a main skeleton and at least one side chain composed of an organic group is preferably used. The organic group here is preferably an organic group having an effect of imparting hydrophobicity to the shell 4, and examples thereof include an alkyl group and a fluoroalkyl group. As such an organic / inorganic composite material, silicone in which the organic group is a methyl group is preferable from the viewpoint of availability.

  The shell 4 may also include a material that adjusts the characteristics of the modeling particles according to the additive manufacturing method. Similarly to the core 3, in the case of particles used for a modeling method that is laminated by heating and pressurization, a viscoelasticity adjusting material for adjusting the viscoelasticity at the time of heating and pressing, and a modeling method that is laminated using an electrophotographic process. In the case of particles to be used, a charge control agent for controlling the chargeability may be included. If the shell 4 contains a charge control agent, charging during frictional charging can be controlled. As the viscoelasticity adjusting material and the charge control agent added to the shell 4, the same material as the core 3 can be used.

In the case of particles used for modeling using an electrophotographic process, the volume resistivity of the shell material is greater than 10 ⁻³ Ω · cm, preferably greater than 10 ⁹ Ω · cm. When it is larger than 10 ⁻³ Ω · cm, the amount of charge attenuation of the particles is small and can be used favorably in the electrophotographic process.

  The thickness of the shell 4 is preferably 0.0010% or more and 15% or less of the particle diameter, and more preferably 1.0% or less. The specific thickness is preferably 1 nm to 10 μm, and more preferably 10 nm to 1 μm. When the thickness of the shell 4 is smaller than 1 nm, moisture tends to enter the core 3 and the strength of the shell 4 tends to be weakened, so that sufficient moisture resistance may not be obtained. Moreover, when larger than 10 micrometers, it exists in the tendency for the formed molded object to become difficult to melt | dissolve or disintegrate with water.

  Here, the thickness of the shell 4 can be measured using an existing method such as a method using an observation image such as an electron microscope or a TEM of a particle cross section, or a method using element mapping. A technique using an observation image such as an electron microscope or a TEM of a particle cross section can measure the ratio and thickness of the shell portion to the particle diameter by breaking an arbitrary shaped particle and observing the particle cross section. At this time, the shell thickness is measured and averaged at at least five locations for one particle. Next, after the shell thickness measurement is performed on at least 10 particles, the average value of the shell thickness between the particles of the modeling particles is calculated to obtain the shell thickness. If the core 3 and the shell 4 cannot be distinguished when observed using an electron microscope or TEM, a method using element mapping may be used. Specifically, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), energy dispersive X-ray analysis (EDX), Auger electron spectroscopy (AES), etc. are used. Thus, the difference in material between the core 3 and the shell 4 can be visualized.

  In the present embodiment, the core 3 does not need to be completely covered with the shell 4, and a part of the core 3 may not be covered with the shell 4. However, the coverage of the shell 4 with respect to the surface area of the core 3 is preferably 30% or more, and more preferably 40% or more. If the coverage is less than 30%, the effect of maintaining the fluidity of the powder by the shell 4 may not be obtained. Further, the coverage of the shell is preferably 95% or less. When the coverage is 95% or less, the exposure of the core 3 is easily promoted during modeling, and the removal rate with water tends to increase.

  The method for obtaining the coverage of the shell 4 is as follows. First, the particle cross section is divided into at least 10 regions so that the areas of the particle surface portions are substantially equal. Then, each divided area is imaged using a microscope or the like, and the ratio of the area where the shell 4 exists, that is, the existence ratio is calculated from the obtained image, and the averaged ratio is defined as the coverage. An electron microscope or the like can be used as the microscope, and staining can be performed as necessary to determine the area between the shell 4 and the core 3. If the shell portion cannot be observed with a microscope, the core 3 and the shell component are identified after the core 3 and the shell 4 are separated, and the coverage is calculated from their abundance ratio. As a method for separating the core 3 and the shell 4, a method for mechanically separating the shell 4 or a method for reprecipitation after selective dissolution with a solvent or the like can be used. For example, a solvent in which only the shell 4 is dissolved is selected, the shell 4 is selectively dissolved, the core portion is removed, and then the shell component is precipitated. Thereafter, a composition analysis of the shell component and the core portion is performed. Regarding the core portion, composition analysis of the core portion may be performed from the cross section of the particle. A calibration curve is prepared with the component amount of the obtained shell material being 100% and the component amount of the core 3 being 0%. The composition analysis of the particle surface is carried out, and the coverage can be calculated from the obtained component amount using the calibration curve.

  The main component of the core 3 and the main component of the shell 4 are preferably different from each other. When the main components of the core 3 and the shell 4 are different, the formation of a three-dimensional network structure made of a water-soluble material contained in the core 3 is promoted when the particles are fused, and the support portion is easily dissolved by water. Or it becomes easy to collapse. The main component in this specification has shown the component with the largest mass content ratio among the components contained in each member.

  The content volume ratio of the water-soluble material of the shaped particles according to this embodiment is preferably 70% or more. When the ratio of the water-soluble material is 70% or more, removal with water tends to be easy.

  The modeling particles are used as a powder during modeling. As long as the powder according to the present embodiment includes the particles according to the present embodiment, the powder may include particles other than the particles according to the present embodiment. However, in order to sufficiently obtain the effects of the present invention, it is preferable that the particles other than the powder according to the present embodiment contained in the powder is 5% or less.

  The volume-based average particle size (hereinafter simply referred to as average particle size) of the modeling particles constituting the powder used for modeling is preferably 1 μm to 100 μm, more preferably 20 μm to 80 μm. . If the average particle diameter of the particles is 1 μm or more, it is possible to increase the thickness of a single laminated film, and thus it is possible to obtain a shaped article having a desired height with a small number of laminations. Moreover, it becomes easy to implement | achieve a highly accurate molded article by making the average particle diameter of particle | grains into 100 micrometers or less.

  The average particle size of the modeling particles constituting the modeling powder can be determined using a commercially available particle size distribution measuring apparatus. For example, when a laser diffraction / scattering particle size distribution analyzer LA-950 (manufactured by HORIBA) is used, the measurement can be performed as follows. The attached dedicated software is used for setting the measurement conditions and analyzing the measurement data. That is, first, a batch type cell containing a measurement solvent is set in a measurement apparatus, and the optical axis and background are adjusted. The solvent used at this time must be selected so that the solubility of the particles is extremely small. Moreover, in order to improve the dispersibility of the particles to be measured, a dispersant may be appropriately added to the solvent as necessary. The powder composed of the particles to be measured is added to the batch cell until the transmittance of light emitted from the tungsten lamp reaches 90% to 95%, and the particle size distribution is measured. The volume-based average particle diameter can be calculated from the obtained measurement results.

  Further, the average circularity of the shaped particles is preferably 0.85 or more, and more preferably 0.90 or more. If the average circularity of the particles is 0.85 or more, the particles come into point contact with each other, so that the particles are easy to flow, and a close-packed arrangement is easily obtained in the particle layer, and voids are formed at the time of lamination. It tends to be difficult to do.

The average circularity can be obtained as follows. First, the circularity of a particle is defined as follows.
Circularity = (perimeter of a circle having the same area as the particle projection area) / (perimeter of the particle projection image)

  “Particle projected area” is the area of a binarized particle image, and “perimeter of particle projected image” is defined as the length of the contour line of the particle image. The circularity is an index indicating the degree of unevenness on the projection surface of the particle, and is 1.0 when the particle is a perfect sphere. The more complex the surface shape, the smaller the circularity. The circularity of the particles can be measured using image processing of an observation image such as an electron microscope and a flow type particle image measuring device. Furthermore, the average circularity can be obtained by taking the average value of the circularity obtained by measuring 10 or more arbitrary shaped particles.

  The powder comprising the shaped particles according to the present embodiment has a moisture content of less than 1.0% by mass. Here, “content of moisture” in this specification refers to the amount of moisture contained in the sample. The moisture content can be evaluated as a weight loss in a temperature range of 25 ° C. or more and 200 ° C. or less when the weight change is measured while heating the sample from room temperature (25 ° C.) to 300 ° C. However, in the case where the temperature range from 25 ° C. to 200 ° C. includes the temperature at which the sample begins to thermally decompose, the moisture content is 25 ° C. or more (Tp− 10) It can be evaluated as a weight loss in a temperature range of not higher than ° C. In addition, said measurement can be measured using a commercially available thermogravimetric analyzer. The rate of temperature rise during measurement is 2 ° C./min, and the atmosphere during measurement is not particularly limited, but is preferably air or nitrogen.

  When the water content is 1.0% by mass or more, there is a risk of causing modeling inhibition due to water content when the modeling particles are used in the manufacturing process of a three-dimensional object. For example, when an electrophotographic method is used as a modeling method, there is a risk that the charge amount of the modeling particles is significantly attenuated. As a result, the development efficiency in the formation stage of the particle layer in which the shaped particles are arranged is lowered, which is not preferable. Further, when heated in the step of laminating the particle layer, the water content is rapidly evaporated and foaming may occur.

<Method for producing shaped particles>
The modeling particle which concerns on the said this embodiment can be manufactured with the manufacturing method which has the process of following (1)-(3) in this order.
(1) Mixing step A powder containing first particles containing a water-soluble material and a powder containing second particles containing a material having a lower solubility in water than the water-soluble material are mixed. To obtain mixed powder.
(2) Drying process The process of drying until the moisture content of mixed powder becomes less than 1.0 mass%.
(3) Compositing step A step of compositing the first particle and the second particle to form a shell containing the most material having a lower solubility in water than the water-soluble material on the surface of the first particle.

  Drawing 1 is a mimetic diagram explaining the manufacturing method of the modeling particle concerning this embodiment. In this embodiment, as shown to Fig.1 (a), first, the mixing process is performed with respect to the 1st particle | grains 1 and the 2nd particle | grains 2, and the mixed powder 6 is obtained. At this time, the second particles 2 are arranged so as to be dispersed on the surface of the first particles 1. Next, the mixed powder 6 is dried to reduce the moisture content to less than 1.0% by mass. Then, the mixed powder 6 is subjected to a composite treatment to convert the second particles 2 arranged on the surface of the first particles 1 into shells 4, and the first particles 1 are converted into the core 3. And the modeling particle | grain 5 which concerns on this embodiment which has the shell 4 which covers the surface of the core 3 is obtained.

  In general, water-soluble materials have high hygroscopicity, and if left in the atmosphere, they continue to absorb moisture until an equilibrium state corresponding to humidity is reached. Here, as shown in FIG. 1 (b), when the first particles 1 containing a water-soluble material are directly subjected to a drying process for the purpose of reducing the water content, it is generally called consolidation. There is a risk of causing aggregation between particles. In addition, the water content in water-soluble materials has the greatest effect on the surface adsorbed water, so once exposed to the atmosphere even after drying, moisture is adsorbed again on the particle surface (re-humidified) and contained. An increase in the amount of moisture may be caused. On the other hand, in the method of the present embodiment shown in FIG. 1 (a), by performing a drying process in a state where the second particles 2 are arranged on the surfaces of the first particles 1, between the particles in the drying step. Consolidation can be suppressed. In addition, it is possible to perform the complexing process immediately after the drying process and form the shell 4 to suppress the re-absorption of the particles and stably maintain the low moisture content even in the atmospheric environment. Become. On the other hand, as shown in FIG. 1 (c), when the first particles 1 and the second particles 2 are combined in advance to form the shell 4 and then dried, the effect of reducing the moisture content is low. It is not preferable. This is because the moisture originally adsorbed on the surface of the first particle 1 is confined in the particle by the shell 4, so that the desorption of moisture during the drying process is inhibited.

  As described above, in the drying process based on the general idea as shown in FIGS. 1B and 1C, it is difficult to obtain shaped particles with high water solubility and suppressed moisture reabsorption. By using the manufacturing method according to this embodiment shown in FIG. 1 (a), it is possible to obtain desired shaped particles. That is, the powder composed of shaped particles produced by the production method according to the present embodiment has a moisture content of less than 1.0% by mass and is reabsorbed even after being exposed to the atmospheric environment for a certain period of time. The accompanying increase in water content is remarkably suppressed. Therefore, by using the modeling particles according to the present embodiment for the modeling of a three-dimensional object, there is no special additional prescription after the modeling of the three-dimensional object while suppressing the modeling inhibition factor caused by the moisture contained in the modeling material. A support portion that can be removed only with water can be formed. Hereinafter, the manufacturing method of the modeling particle which concerns on this embodiment is demonstrated in detail.

[First particle]
The first particles 1 contain a water-soluble material. Since the first particle 1 becomes the core 3, the water-soluble material constituting the first particle 1 and other materials are as described for the core 3 of the shaped particle 5. The average particle diameter of the first particles 1 is preferably 1 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less from the viewpoint of modeling performance as the modeling particle 5.

  The method for granulating the first particles 1 is not particularly limited, but spray drying is used from the viewpoint that the obtained shape is close to a true sphere, the granulation cost is relatively low, and the throughput during granulation is relatively high. The method is preferred. The granulated particles are classified as necessary, and are used after being classified into a particle group having a desired average diameter and particle size distribution, so that stable modeling can be performed in the manufacturing process of a three-dimensional object. Preferred above.

[Second particle]
The second particle 2 contains a material having a lower solubility in water than the water-soluble material contained in the first particle 1. Since the second particle 2 becomes the shell 4, the shaped particle 5 is used for a material having a lower solubility in water than the water-soluble material contained in the first particle 1 and constituting the second particle 2. The shell 4 is as described above.

  The average particle size of the second particles 2 is preferably 1/10 or less of the average particle size of the first particles 1, and more preferably 1/100 or less. When the average particle size is 1/10 or less, the second particles 2 are evenly dispersed and arranged on the surface of the first particles 1, and the caking prevention effect in the drying process is improved. Also in the compounding step, it is effective to form the shell 4 with a high coverage.

[Mixing process]
By mixing the powder containing the first particles 1 and the powder containing the second particles 2, a mixed powder 6 is obtained. At this time, the mass ratio of the second particles 2 to the first particles 1 is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less. If the mass ratio is 0.5% by mass or more, the caking prevention effect in the drying process is sufficient, and a sufficient coverage is achieved during the compounding process. On the other hand, if the mass ratio is 10% by mass or less, there is little possibility that particles that do not contribute to shell formation remain in the compounding step. Since such residual particles may act as a contamination source for various members in the manufacturing process of a three-dimensional object, it is preferable to reduce as much as possible.

  The method of the mixing treatment is not particularly limited as long as the state in which the second particles 2 are uniformly dispersed on the surface of the first particles 1 is achieved. Specifically, a method of shaking the whole container in a mixed state in a closed container, a method of performing a rotation process with a screw or the like in the closed container, and the like are included.

[Drying process]
The mixed powder 6 obtained by the mixing step is dried until the moisture content is less than 1.0% by mass. There is no restriction | limiting in particular in the system of a drying process, The processing method generally used in order to reduce the water | moisture content in a powder can be used. For example, there is a method in which the mixed powder 6 is introduced into a sealed container and the mixed powder 6 is heated and stirred for a predetermined time in a dry gas environment or a reduced pressure environment. The drying temperature at this time is preferably as high as possible within a range in which the first particles 1 and the second particles 2 do not undergo alteration or modification such as melting and oxidation. Specifically, it is preferable to appropriately select the temperature and the treatment time in the range of 50 ° C. to 150 ° C. according to the type of material. In the present embodiment, by adopting a mixed powder form, consolidation between the first particles 1 in the drying step is suppressed. For the drying process, a stationary oven or the like may be used. However, in order to further increase the effect of suppressing consolidation, the drying process may be performed while the mixed powder 6 is fluidized by stirring or the like. As an apparatus for performing a drying process while flowing particles, a rocking dryer (manufactured by Aichi Electric Co., Ltd.), a nauta mixer (manufactured by Hosokawa Micron Corporation), or the like is preferably used.

[Composite process]
After the drying step, the first particle 1 and the second particle 2 are combined, and the shell 4 containing the most material having a lower solubility in water than the water-soluble material is formed in the core 3 formed by the first particle. Form on the surface. Here, in order to maintain the moisture content reduced by the drying step, for example, the mixed powder 6 is handled in a reduced pressure atmosphere or an inert gas atmosphere from the end of the drying step to the end of the compounding step. It is preferable not to expose to the atmosphere as much as possible.

  Compounding gives a powder in which raw materials such as multiple types of powders are combined by applying mechanical action including compressive force, shearing force and impact force to raw materials such as multiple types of powders. It is preferable to use a dry compounding apparatus capable of Examples of such an apparatus include Nobilta (manufactured by Hosokawa Micron Corporation) and a hybridization system (manufactured by Nara Machinery Co., Ltd.).

  The shell 4 preferably covers the surface of the core 3 completely, but the surface of the core 3 is not partially covered with the shell 4 as long as the inhibitory effect on the three-dimensional object forming process is not significant. There may be areas.

<Method for producing a three-dimensional object>
The manufacturing method of the three-dimensional object using the modeling particles according to the present embodiment is not particularly limited, and methods such as a layered modeling method, a binder injection method, a material extrusion method, and a material injection method are used. Hereinafter, an example of manufacturing a water-insoluble three-dimensional object while modeling a support portion that can be removed by water after modeling using the modeling particles according to the present embodiment as support material particles by the additive manufacturing method will be described. The characteristics required for modeling particles in the additive manufacturing method will also be described.

The manufacturing method of the three-dimensional object of this embodiment includes the following steps (I) to (III) using water-insoluble structural material particles and support material particles as modeling particles.
(I) The step of arranging the structural material particles and the support material particles to form the particle layer (II) The step of laminating the particle layers to form the shaped product (III) The support part included in the shaped product is water The step (I) and the step (II) are repeated by removing the contact portion in contact with the solvent containing the step (III), and if the step (III) is performed on the molded article obtained by laminating the required number of particle layers, the support part is The three-dimensional object which is a modeling target object can be obtained selectively. Hereinafter, each process will be described in detail.

(I) A step of arranging the structural material particles and the support material particles to form a particle layer In this step, the structural material particles and the support material particles are arranged based on the three-dimensional data of the object to be shaped, and the particle layer Form. Specifically, 3D data is generated by adding the support part necessary for the modeling process to the 3D data of the modeling object, and slice data is created by slicing the 3D data with the support part at a predetermined interval. To do. According to the obtained slice data, the structural material particles and the support material particles are arranged, and a particle layer is formed.

  As will be described later, when laminating the particle layer in the step (II), if the particles are fused by applying thermal energy, it is preferable that the shaped particles contain a thermoplastic material. A thermoplastic material refers to a material that has the property of hardly changing at room temperature but exhibiting plasticity by heating at a temperature corresponding to the material, allowing free deformation, and becoming hard again when cooled.

  As the thermoplastic material contained in the structural material particles, any known material having the above-mentioned characteristics may be used. For example, ABS, PP (polypropylene), PE (polyethylene), PS, which are thermoplastic resins, may be used. (Polystyrene), PMMA (acrylic), PET (polyethylene terephthalate), PPE (polyphenylene ether), PA (nylon / polyamide), PC (polycarbonate), POM (polyacetal), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide) PEEK (polyether ether ketone), LCP (liquid crystal polymer), fluororesin, urethane resin, elastomer, PVA (polyvinyl alcohol), PEG (polyethylene glycol), and other metals and inorganic substances . These substances may be used alone or in combination.

  The material constituting the structural material particles may be selected according to the function required for the modeling object, and may contain a functional substance such as a pigment. The softening temperature and melting temperature of the material constituting the structural material particles can be appropriately selected depending on the temperature at which the particle layer is fused in the subsequent laminating step (II), but is preferably 40 ° C. or higher and 300 ° C. or lower. . By being 40 degreeC or more, a molded article becomes difficult to deform | transform, and control of the melting process performed at the process of (II) becomes easy by being 300 degrees C or less.

  Although the formation method of a particle layer is not specifically limited, From the viewpoint of modeling speed, the method of arrange | positioning by a line unit or a surface unit is preferable. For the formation of the particle layer in which the shaped particles are arranged in units of lines or planes, a known method such as a method using an electrostatic action by charging can be used. When forming a particle layer containing a plurality of types of modeling particles as in the present embodiment, a method using an electrophotographic method is particularly preferable. According to this method, each particle can be arranged at a position according to slice data using the number of photoconductors corresponding to the type of particles used for modeling, and an accurate particle layer can be formed.

  When the modeling particles according to the present embodiment are applied to an electrophotographic additive manufacturing method, charging attenuation, which is a problem of modeling particles containing a water-soluble material, is suppressed. That is, since the water-soluble material is generally hydrophilic, the charged amount of the charged particles may be attenuated by adsorbing moisture in the atmosphere on the surface. If an electrophotographic method is performed using particles of a water-soluble material that does not have a shell as in this embodiment, the charge amount is attenuated in the process of forming the particle layer, and the modeling particles cannot be arranged at a predetermined position. Defects may occur. On the other hand, in the particles having the configuration of the present embodiment, moisture adsorption on the surface of the water-soluble material is suppressed by the shell, so that attenuation of the charge amount is suppressed. The decay rate α of the surface potential of the shaped particles is preferably less than 0.3, more preferably 0.2 or less, and more preferably 0.1 or less. When the attenuation rate α is less than 0.3, the charged particles maintain the charge, so that the particle layer can be formed using an electrophotographic method. Further, when the attenuation rate α is 0.1 or less, a stable charge amount can be maintained by charging, and therefore, it is more preferable as a modeling particle used in the electrophotographic system. The charge amount and the decay rate α can be adjusted to desired values by appropriately selecting the material and thickness constituting the shell.

  In addition, the presence of the shell suppresses changes in the viscosity of the particle surface due to moisture adsorption on the core, so that the fluidity of the powder is maintained, and a sufficient initial charge can be secured by increasing the number of contact between particles. It is thought that it becomes.

(II) Step of forming a shaped product by laminating particle layers This step is a step of repeatedly laminating the particle layer obtained in the step (I) to obtain a shaped product. For the layering of the particle layer, a particle layer formed separately may be stacked on the surface of the previously formed particle layer, or a new particle layer may be formed directly on the surface of the previously formed particle layer. However, they may be laminated. When laminating the particle layer formed as a separate body on the surface of the previously formed particle layer, the particle layer may be once formed on the substrate and then transferred to the surface of the previously formed particle layer. The base material used at this time is called a transfer body. When the particle layer is formed on the transfer body, a known transfer method such as electrostatic transfer using electrostatic force can be used.

  Fusion between the particles constituting the particle layer may be performed before lamination, at the same time as lamination, or after lamination, or may be performed at a plurality of timings among them. For example, any of the following methods (i) to (iii) can be applied. (Ii) (iii) is preferable because the number of modeling particles in the particle layer to be melted at one time is smaller than that in (i), so that voids are hardly generated inside the modeled article.

(I) Method of fusing modeling particles after laminating a plurality of particle layers (ii) Method of fusing modeling particles every time one particle layer is laminated (iii) In the particle layer before lamination In (i) to (iii), the case where thermal energy is used for fusing between shaped particles has been described, but a method of chemically fusing using chemicals may also be used. it can. However, the method in which the modeling particles are melted by applying thermal energy is preferable because energy is given to the entire particle layer and particle melting proceeds in the entire region, so that the effect of reducing voids is large.

(III) The process of removing the support part contained in a model by making it contact with the solvent containing water The modeled object produced by repeating the process of (I) and (II) as many times as necessary is used for the solvent containing water. Make contact. The entire model is immersed in a solvent, or the solvent is ejected in a shower shape and bathed on the model, and the model is brought into contact with a solvent containing water. When the modeled object comes into contact with a solvent containing water, the water-soluble material contained in the support part is dissolved. The shell debris contained in the support part is not easily dissolved because of its low solubility in water, but is removed from the structure part together with the water-soluble material. Since the structure portion is made of a water-insoluble material, there is no fear that the structure portion is dissolved in a solvent containing water, and there is no possibility that the shape changes due to the removal of the support portion. In the case of removing the support portion by immersing the entire modeled object in a solvent, it is preferable to add a water flow or ultrasonic vibration to the solvent because dissolution or collapse of the support portion is promoted.

  The modeling particles according to this embodiment have high moisture resistance in the particle state, and can be dissolved or disintegrated with water after modeling. In order to realize this state, it is preferable that the component ratio of the chemical species on the surface of the modeled object is different from the component ratio of the chemical species on the surface of the particle before modeling, and the main components are different. Is more preferable. This suggests that the material component exposed on the surface changes between the particle state and the modeled object state through the modeling process. As a technique for analyzing the main component of the chemical species, an existing technique such as surface element analysis can be used. For example, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), energy dispersive X-ray analysis (EDX), Auger electron spectroscopy (AES), or the like can be used. The surface elemental analysis may be performed on the particles and the modeled object to confirm that the main components of the surface chemical species are different. Specifically, it is possible to analyze the chemical species on the surface from the difference in element type, elemental composition ratio, and the like.

  In this way, the material component exposed to the surface in the modeled object state changes with respect to the particle state in the modeling process due to the temperature applied to the modeled particle or the deformation of the particle due to temperature and pressure. The The conditions for changing the material component exposed on the surface of the modeled object state with respect to the particle state vary depending on the coverage of the shell on the core surface in the particle state and the combination of the core and shell materials. For example, when the covering ratio of the shell is close to 100%, the particles may be heated to a temperature higher than the softening temperature of the core or the shaped particles and simultaneously pressurized, and deformed until the deformation rate reaches a height of 90% or less. Then, since the shell is easily broken and the material contained in the core is easily exposed on the surface, the effect of the present invention can be more suitably obtained. In order to know how much deformation has been applied in the modeling process from the modeled object, the ratio of the value obtained by dividing the thickness of the modeled object by the number of layers and the thickness of the particle layer may be estimated as the deformation rate. Thereby, the deformation | transformation added to particle | grains can be estimated by one lamination. Moreover, when the deformation | transformation of particle | grains can be observed, particle | grains after pressurization with respect to the average particle diameter of the particle | grains before shaping | molding are directly observed, and it is good also as a deformation rate.

<Modeling equipment>
Next, an apparatus suitable for modeling using the modeling particles according to the present embodiment will be described. For example, in the electrophotographic system, the modeling apparatus 500 shown in FIG. 2 is preferably used. The modeling apparatus 500 includes a particle layer forming unit 501, a modeling unit 502, and a transfer body 24 that connects the particle layer forming unit and the modeling unit.

  The particle layer forming unit 501 includes a material supply unit 21, a photoreceptor 22, and a light source (not shown) according to the number of types of modeling particles, and forms a particle layer on the transfer body 24. Although FIG. 2 shows a configuration in which one type of each of the structural material particles and the support material particles is used, the material supply unit 21 provided in the particle layer forming unit 501 and the photoconductor according to the number of types of modeling particles to be used. 22. What is necessary is just to increase the set of light sources.

  A particle layer made of structural material particles and a particle layer made of support material particles are formed on separate photoreceptors 22a and 22b, respectively. A laser beam 23a emitted from the light source scans the photoconductor 22a and a laser beam 23b scans the photoconductor 22b, so that latent images are formed on the photoconductors 22a and 22b. Specifically, the latent image of the structure portion of the slice data is formed on the photoconductor 22a, and the latent image of the support portion of the slice data is formed on the photoconductor 22b.

  The material supply unit 21a stores powder containing structural material particles, and the material supply unit 21b stores powder containing support material particles. The structural material particles are supplied to the photoconductor 22a from the material supply unit 21a, and a layer made of the structural material particles is formed on the photoconductor 22a. Further, the support material particles are supplied from the material supply unit 21b to the photoconductor 22b, and a layer made of the support material particles is formed on the photoconductor 22b. The layer formed on each of the photoreceptors 22a and 22b is electrostatically transferred to the transfer body 24 in order to form a particle layer composed of structural material particles and support material particles. The order of transferring the particle layer to the transfer body 24 is not limited to this, and after transferring the particle layer made of one of the structural material particles and the support material particles, the particle layer made of the other particle. It is good to transfer and form.

  The particle layer formed on the transfer body 24 is heated, and transferred and stacked on a modeled object on the stage 25 during modeling. At the time of stacking, the opposing member 26 and the stage 25 can pressurize the modeled object in the middle of modeling and the heated particle layer. The particle layer may be heated by the facing member 26 incorporating a heater, or may be heated by a heating means different from the facing member 26. As a result, a modeled object composed of the structure portion 27a formed from the structural material particles and the support portion 27b formed from the support material particles is formed. The modeling apparatus suitable for the electrophotographic system is not limited to the configuration shown in FIG.

  It is preferable to integrate the functions of the material supply unit 21 and the photosensitive member 22 into a cartridge and to make the modeling apparatus have a structure in which the cartridge can be replaced because it is easy to replenish and replace the material. The cartridge includes a photoconductor, a charging unit for charging the photoconductor, an opening for irradiating the photoconductor with laser light, and a material container and a material supply unit corresponding to the material supply unit. It is good to have.

  When using the modeling particles according to the present embodiment as the support material particles, the modeling apparatus includes at least the cartridge containing the powder containing the structural material particles in the material container and the modeling particles according to the embodiment in the material container. The cartridge containing the contained powder is detachable. Furthermore, it is also preferable to include an attaching / detaching part to which the spare cartridges of the structural material particles and the support material particles can be attached and detached so that the modeling particles do not run out during modeling.

  As described above, when manufacturing a water-insoluble three-dimensional object using the layered modeling method, the case where the modeling particle of the present invention is used as the support material particle has been described, but the use of the modeling particle according to the present embodiment is here It is not limited. For example, when a water-soluble three-dimensional object is manufactured by the layered modeling method, the modeling particle according to the present embodiment is suitable as the structural material particle.

<Example 1>
(1) Mixing Step As the first particles, particles having an average particle size of 25 μm including maltotetraose, lactitol, and cellulose nanofibers were produced by a spray drying method. At this time, the mass ratio of maltotetraose, lactitol, and cellulose nanofiber was 70:30:15. In addition, the solubility with respect to the water of a 1st particle | grain is 50 or more. To this first particle, styrene-acrylic copolymer fine particles (average particle size 0.4 μm, manufactured by Soken Chemical Co., Ltd.) are mixed and stirred as a second particle at a ratio of 2% by mass, and mixed powder The body. In addition, the solubility with respect to the water of a styrene-acryl copolymer is 1 or less.

(2) Drying step The mixed powder was subjected to a drying treatment by being held in a drying oven at 80 ° C. for 15 hours. As a result, the water content of the mixed powder is less than 1.0% by mass.

(3) Compounding step After the drying treatment, the mixed powder was held in a sealed container so as not to be exposed to the atmosphere as much as possible, and then charged into a dry compounding device Nobilta NOB-300 (made by Hosokawa Micron) whose inside was replaced with nitrogen. . The composite treatment was performed at a rotor load of 18.5 kW for 3 hours to obtain a powder composed of particles having a first particle as a core and a styrene-acrylic copolymer as a shell.

(4) Evaluation About the powder obtained by the above, the mass change at the time of heating from room temperature (25 degreeC) to 300 degreeC with the temperature increase rate of 2 degree-C / min is shown as the continuous line in FIG. At this time, the mass reduction rate in the temperature range of 25 ° C. or higher and 200 ° C. or lower, that is, the water content was 0.25% by mass.

  When this powder was used as a support material in the modeling of a three-dimensional object using an electrophotographic method, an event that could be a modeling hindering factor such as poor development or foaming in the modeling process did not occur, the formation of a support part, and The support part could be removed with water.

<Comparative Example 1>
A powder was produced in the same manner as in Example 1 except that the drying step was not performed. The mass change of this powder measured in the same manner as in Example 1 is shown by the dotted line in FIG. At this time, the water content was 2.1% by mass.

  When this powder is used as a support material in modeling a three-dimensional object using an electrophotographic method, foaming may occur in the support portion during the heating step in the lamination process.

<Comparative example 2>
The 1st particle | grains same as Example 1 were hold | maintained for 15 hours in 80 degreeC drying oven, and the drying process was performed. After the drying treatment, aggregation due to consolidation occurred between the first particles, and fluidity as a powder was lost.

<Comparative Example 3>
A powder was produced in the same manner as in Example 1 except that the order of the drying step and the compounding step was changed. About this powder, the moisture content measured like Example 1 was 2.1 mass%.

  When this powder is used as a support material in modeling a three-dimensional object using an electrophotographic method, foaming may occur in the support portion during the heating step in the lamination process.

<Example 2>
(1) Mixing step A mixed powder was produced in the same manner as in Example 1.

(2) Drying step The mixed powder was subjected to a drying treatment at 100 ° C. for 5 hours in a circulation environment with a moisture absorber using a container rotary swing dryer (manufactured by Aichi Electric Co., Ltd.). As a result, the water content of the mixed powder is less than 1.0% by mass.

(3) Compounding step Compounding was performed in the same manner as in Example 1.

(4) Evaluation About the powder obtained by the above, the moisture content measured similarly to Example 1 was 0.25 mass%.

  When this powder was used as a support material in the modeling of a three-dimensional object using an electrophotographic method, an event that could be a modeling hindering factor such as poor development or foaming in the modeling process did not occur, the formation of a support part, and The support part could be removed with water.

1: first particle, 2: second particle, 3: core, 4: shell, 5: shaped particle, 6: mixed powder

Claims (20)

A mixed powder obtained by mixing a powder containing first particles containing a water-soluble material and a powder containing second particles containing a material having a lower solubility in water than the water-soluble material. A mixing step to obtain,
A drying step of drying until the water content of the mixed powder is less than 1.0% by mass;
A composite step of combining the first particles and the second particles, and forming a shell containing the most material having a lower solubility in water than the water-soluble material on the surface of the first particles;
In this order, the manufacturing method of the modeling particle | grain characterized by the above-mentioned.   2. The method for producing shaped particles according to claim 1, wherein an average particle diameter of the second particles is 1/10 or less of an average particle diameter of the first particles.   The method for producing shaped particles according to claim 1 or 2, wherein a mass ratio of the second particles to the first particles is 0.5 mass% or more and 10 mass% or less.   The compounding step is a step of compounding the first particles and the second particles by applying a mechanical action including compressive force, shear force, and impact force to the mixed powder. The manufacturing method of the modeling particle | grains as described in any one of Claims 1 thru | or 3 characterized by the above-mentioned.   The method for producing shaped particles according to any one of claims 1 to 4, wherein the compounding step is performed in an inert gas atmosphere.   The method for producing shaped particles according to any one of claims 1 to 5, wherein the mixed powder is not exposed to the air between the drying step and the compounding step.   The method for producing shaped particles according to any one of claims 1 to 6, wherein the water-soluble material is a water-soluble carbohydrate.   The method for producing shaped particles according to claim 7, wherein the water-soluble carbohydrate is a carbohydrate.   The method for producing shaped particles according to claim 8, wherein the sugar is maltotetraose or lactitol.   The method for producing shaped particles according to any one of claims 1 to 9, wherein a material having a lower solubility in water than the water-soluble material is a resin.   The method for producing shaped particles according to claim 10, wherein the resin is a styrene-acrylic copolymer, polymethyl methacrylate, or polystyrene.   The method for producing shaped particles according to any one of claims 1 to 11, wherein the first particles contain nanofibers. Modeling particles containing a water-soluble material,
A core and a shell covering at least part of the surface of the core;
The core contains the most water-soluble material,
The solubility in water of the material most contained in the shell is smaller than the solubility in water of the water-soluble material contained in the core,
A shaped particle, wherein the water content of the powder composed of the plurality of shaped particles is less than 1.0% by mass.   The shaped particle according to claim 13, wherein the water-soluble material is a water-soluble carbohydrate.   The shaped particle according to claim 14, wherein the water-soluble carbohydrate is a carbohydrate.   The shaped particle according to claim 15, wherein the carbohydrate is maltotetraose or lactitol.   The shaped particle according to any one of claims 13 to 16, wherein the material most contained in the shell is a resin.   The shaped resin according to claim 17, wherein the resin is a styrene-acrylic copolymer, polymethyl methacrylate, or polystyrene.   A powder comprising the shaped particles according to any one of claims 1 to 18. Arranging the structural material particles and the support material particles to form a particle layer;
Laminating the particle layer to form a shaped article;
A step of removing the part made of the support material particles of the shaped article by contacting with a solvent containing water, and
The modeling particle according to any one of claims 1 to 18 is used as the support material particles.

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