WO2016047549A1 - Modeling particles used for manufacturing three-dimensional object, powder including same, and method for manufacturing three-dimensional object using same - Google Patents

Abstract

　The present invention makes it possible to provide modeling particles including a water-soluble material, whereby a support body removable by a water-containing solvent in a process for manufacturing a three-dimensional object can be formed despite the high fluidity in a powder state. Modeling particles used for manufacturing a three-dimensional object, the modeling particles being provided with a core and a shell for covering at least a portion of the surface of the core, the water-soluble material being contained most abundantly in the core, and the water solubility of a material included most abundantly in the shell being less than the water solubility of the water-soluble material included in the core.

Description

Shaped particles used for manufacturing a three-dimensional object, powder containing the same, and method for manufacturing a three-dimensional object using the same

This invention relates to the modeling particle | grains used for manufacture of a solid thing using the additive manufacturing method.

In recent years, a layered modeling method in which modeling materials are laminated based on cross-sectional data of a three-dimensional object (modeling object) that is a modeling object has attracted attention.

Patent Document 1 discloses a method in which particles (modeling particles), which are modeling materials, are arranged in accordance with cross-sectional data of a modeling target using an electrophotographic method, and then the molding particles are fused to each other by heat and stacked. It is disclosed.

In Patent Document 2, a layer made of modeling particles is formed on a base, and a binder liquid is sprayed or irradiated with a laser beam in accordance with cross-sectional data of a modeling target to partially dissolve the modeling particles and melt them together. A method of wearing and laminating is disclosed.

In the additive manufacturing method, when a complicated shape having an overhang structure, a structure having a movable part, or the like is produced, it is necessary to form a structure on a region where the structure constituting the modeling target does not exist. In such a case, a support body that supports the structure is provided below the structure in the direction of gravity. That is, in the modeling process, a support body is formed as necessary in a region that becomes a void of the modeling target.

Since the support body is an unnecessary member for the modeling object, it is removed after the modeling is completed. Therefore, it is desirable that the support body be formed of a material that can be easily removed from the surface of the structure body made of the structural material.

In Patent Literature 1, particles containing a material constituting a modeling object (structure) composed of particles (support material particles) containing a material constituting the support body and a resin having a higher softening temperature after modeling than the support material particles. The laminate is formed using the material particles. After the modeling, the structure is heated to a temperature equal to or higher than the melting temperature of the support material particles and does not melt, and the support body is selectively removed by melting to obtain a structure, that is, a modeling object.

Patent Document 2 includes a core made of metal, ceramic, plastic or the like, a first coating film made of a material having polarity formed on the surface of the core, and a surfactant formed on the first coating film. A modeling method using particles having a second coating film is disclosed. In Patent Document 2, a layer made of such particles is disposed on the base, and a step of spraying a binder liquid that dissolves the first and second coating films or irradiating a laser beam according to a predetermined pattern, Modeling is done by joining particles together. The region of the particles that are not fused with other particles without being sprayed with the binder liquid or without being irradiated with the laser beam plays a role as a support body, and supports the lamination of the particles that become the structure.

JP 2003-53849 A JP 2005-533877 A

However, in the method described in Patent Document 1, the support body may remain on the surface of the structure body, and the structure body is deformed by heat applied when the support body is removed, and a desired modeling object is obtained. There may not be.

In the case of Patent Document 2, since the structure is fixed by fusing the first coating film on the surface layer at the contact point between the particles, the bond is weak and the load applied to the structure when the support body is removed. There is a risk that the modeling object will be broken.

In order to solve the above problems, the present invention provides a shaped particle suitable for the structure of a support body, which can be easily removed from the surface of the structure with a solvent containing water while suppressing deformation of the structure. An object of the present invention is to provide a method for producing a three-dimensional object using these.

The shaped particle according to the present invention is a particle containing a water-soluble material, and includes a core and a shell covering at least a part of the surface of the core, and the core contains the most water-soluble material, The solubility of the material most contained in the shell in water is smaller than the solubility in water of the water-soluble material contained in the core.

According to the present invention, it is possible to provide shaped particles suitable for manufacturing a three-dimensional object that can be easily removed by bringing the support body into contact with a solvent containing water.

It is a figure explaining the modeling particle | grains of this invention. It is a schematic diagram of the process of laminating | stacking a particle layer. It is an electron microscope image of the cross section of the particle | grains in the powder N produced in the Example of this invention. It is a photograph which shows the state of the powder I after leaving still in a humidity environment. It is a photograph which shows the state of the powder P after leaving still in a humidity environment. It is an example of the graph of charging attenuation. It is a schematic block diagram of the three-dimensional modeling apparatus using an electrophotographic system.

Hereinafter, the present invention will be described in detail with reference to the drawings. In each drawing, the same code | symbol is provided to the location which shows the same member or a corresponding member. A well-known technique or a well-known technique in the technical field can be applied to configurations and processes that are not particularly illustrated or described. In addition, overlapping description may be omitted.

<Modeling particles>
In general, a modeling object is often made of a water-insoluble material such as ABS or nylon. Therefore, if the support material particles are water-soluble, the support body can be selectively removed using the difference in solubility in water. If water can be used for the removal of the support body, it is very preferable because water can be easily obtained because the cost can be kept low and the safety is high and the load on the environment is low. 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. Moreover, the solubility with respect to 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 water removability, the support body is preferably made of a water-soluble material having a 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.

Therefore, the modeling particle according to the present invention has the shell 11 on the surface of the core 12 as in the cross-sectional structure shown in FIG. Here, the core does not need to be entirely covered with the shell as shown in FIG. 1, and the modeling particle according to the invention includes the core 12 and the shell 11 covering at least a part of the surface of the core 12. That's fine. Furthermore, the core 12 contains the most water-soluble material, and the solubility in water of the material most contained in the shell 11 is smaller than the solubility in water of the water-soluble material contained in the core 12. The solubility of the core 12 and the shell 11 can be measured by separating each part from the particle.

The shaped particles having such a structure can be obtained by applying thermal energy or thermal energy and pressure under appropriate conditions according to the coverage of the shell to the core surface and the material of the core or shell. Can be exposed to. For example, the shell structure is destroyed by heating at the same time or higher than the softening temperature of the core or modeling particles, or by heating at the same time as the softening temperature of the core or modeling particles, and the core material is exposed to the surface. it can. Here, the softening temperature of the present invention refers to the temperature at which the loss elastic modulus becomes 10 ⁸ Pa or less when dynamic viscoelasticity is measured. Here, the softening temperature of the modeling particle refers to a temperature at which the loss elastic modulus of the modeling particle including the core and the shell becomes 10 ⁸ Pa or less.

Alternatively, a solution that selectively dissolves the shell material may be sprayed onto the shaped particles, and the shell material may be unevenly distributed on the particle surface using the surface tension of the droplets formed on the particle surface to expose the core material. Is possible.

Thus, since the modeling particle | grains of this invention have the material (shell 11) with the low solubility with respect to water on the surface, the aggregation by moisture absorption is suppressed also in the atmosphere with much moisture content in the state of a powder. Thus, 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.

In the manufacturing process of the three-dimensional object, the core material extruded from the inside of the plurality of modeling particles is fused to form a three-dimensional object by heating and pressurizing at a temperature higher than the softening temperature of the core or the modeling particle. it can. Alternatively, in the manufacturing process of the three-dimensional object, the core material is exposed by spraying a solution that selectively dissolves the shell and then dried, and a plurality of particles are bound by the shell material, and the three-dimensional object is bonded. Can also be formed.

Since the core 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 the above properties, the shaped particles according to the present invention are suitable as support material particles. When the modeling particle | grains concerning this invention are used as support material particle | grains, it can remove from a structure easily by making a support body contact water after modeling. Therefore, the shape of the structure is not impaired by the support body removal 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 ensure the removability of the support body, the support body has a structure in which the water-insoluble material of the shell is scattered in the three-dimensional network structure made of the water-soluble material of the core. desirable. For this purpose, the core 12 needs to include 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 12 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 or shell, the mass ratio of the water-soluble material contained in the core of the support material particles to the entire core 12 is preferably 50% or more, and 70% or more. Is more preferable.

The water-soluble material contained in the core 12 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 12. Therefore, the volume ratio or mass ratio of the water-soluble material relative to the entire core 12 may be calculated 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.

When there are a plurality of types of water-soluble materials contained in the core 12, the solubility of water contained in the shell most in the material is smaller than the solubility in water of the water-soluble material contained in the core. This means that the solubility of water-soluble material in water is smaller than the solubility in water.

The water-soluble material contained in the core is not particularly limited as long as it has water solubility, but is preferably a material having a solubility in water of greater than 1, more preferably a material of greater than 5, and even more preferably of 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 dietary fibers, water-soluble carbohydrates such as carbohydrates, polyalkylene oxide, polyvinyl alcohol (PVA), and polyethylene glycol (PEG) are preferable. Specific examples of the water-soluble dietary fiber include polydextrose and inulin, and specific examples of the carbohydrate include sucrose, lactose, maltose, trehalose, melezitose, stachyose, and maltotetraose. A specific example of the polyalkylene oxide is polyethylene glycol (PEG).

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

For example, in the case of particles used in a modeling method that is laminated by heating and pressing, a viscoelasticity adjusting material for adjusting the viscoelasticity during 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.

Also, 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 during viscous flow. Examples of the fiber material include water-insoluble fibers (hereinafter referred to as nanofibers) having a nano-sized diameter or length. This is because by containing nanofibers in the core main component, a matrix made of nanofibers can be formed inside the base material, and it becomes easy to increase the viscoelasticity of the base material.

Also, 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 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.

An organometallic compound or a chelate compound is effective as a charge control agent for controlling particles to be negatively charged. 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. Further, 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 modeling particles may contain these charge control agents alone or in combination of two or more.

The material most contained in the shell 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, but a material having a solubility in water of less than 10 is preferable, and a material of less than 5 is more preferable. 1 or less is more preferable.

Examples of the material most contained in the shell 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, the present invention 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.

In addition, inorganic oxides such as silicon oxide, titanium oxide, and alumina can be suitably used as long as they are inorganic. 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 having at least one side chain composed of an organic group is preferably used. The organic group herein is preferably an organic group having an effect of imparting hydrophobicity to the shell, 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 may also include a material that adjusts the characteristics of the modeling particles according to the additive manufacturing method. Similar to the core, in the case of particles used for modeling by laminating by heating and pressurization, viscoelasticity adjusting material for adjusting viscoelasticity at the time of heating and pressing, used for modeling by laminating using electrophotographic process In the case of particles, a charge control agent for controlling the chargeability may be included. If the shell contains a charge control agent, charging during frictional charging can be controlled. As the viscoelasticity adjusting material and charge control agent to be added to the shell, the same material as the core can be used.

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

It is preferable that the main component of the core and the main component of the shell are different from each other. The difference between the core and shell components facilitates the formation of a three-dimensional network structure consisting of water-soluble materials contained in the core when the particles are fused together, and the support body is easily dissolved or disintegrated by water. It becomes easy. The main component in this invention has shown the component with the largest mass content ratio among the components contained in each member.

The volume ratio of the water-soluble substance in the shaped particles according to the present invention is preferably 70% or more. When the ratio of the water-soluble substance is 70% or more, removal with water tends to be easy.

The thickness of the shell 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 is smaller than 1 nm, moisture tends to enter the core and the strength of the shell 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 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, a method using element mapping, or the like.

The method 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 relative to the particle diameter by rupturing any 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 and shell 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 and the shell can be visualized.

In the present invention, the core does not need to be completely covered with the shell as shown in FIG. 1, and a part of the core may not be covered with the shell. However, the coverage of the shell with respect to the surface area of the core 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 in an environment where the humidity is not controlled may not be obtained.

Also, the coverage of the shell of the present invention is preferably 95% or less. When the coverage is 95% or less, the exposure of the core is easily promoted during modeling, and the removal rate with water tends to increase.

The method for obtaining the shell coverage 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 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 and the core.

If the shell portion cannot be observed with a microscope, the core and shell components are identified after the core and shell are separated, and the coverage is calculated from their abundance ratio. As a technique for separating the core and the shell, it is possible to use a technique for mechanically separating the shell or a technique for reprecipitation after selective dissolution with a solvent or the like. For example, a solvent in which only the shell is dissolved is selected, the shell 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 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 shaped particles can be produced by a known method. A method of forming a core and a shell at the same time may be used, or a method of forming a shell on a core prepared in advance may be used. When the core and the shell are formed at the same time, a suspension polymerization method, an emulsion polymerization method, or the like can be used.

When the shell is formed on the core prepared in advance, the phase separation method, submerged drying method, melt dispersion cooling method, spray drying method, pan coating method, interfacial polymerization method, submerged effect coating method, air suspension coating Method, mechanofusion method, mechanochemical method and the like can be used. The core is prepared by mechanical pulverization, a spray-drying method in which particles are obtained by dispersing and cooling in a gas (liquid) medium in a solution state or a molten state, a melt dispersion cooling method, and a method for producing polymer particles in the medium. A chemical polymerization method such as a turbid polymerization method can be used. Among these, a production method using a medium is preferable in that the shape of particles and the particle size distribution of powder can be controlled relatively freely, and a spray drying method is particularly preferable.

The obtained powder is classified as necessary. Classification can be appropriately selected from classification by mesh (sieving) and air classification such as elbow jet. In order to obtain a desired average particle diameter and particle size distribution, a plurality of classifiers may be used in combination, or classification may be performed in a plurality of times.

<Method for producing a three-dimensional object>
Next, an example of manufacturing a water-insoluble three-dimensional object while modeling a support body that can be removed by water after modeling using the modeling particles according to the present invention as support material particles in the additive manufacturing method will be described. The characteristics required for modeling particles in the additive manufacturing method will also be described. In the modeling method described below, the modeling particles are used as a powder. The powder at this time may contain other particles as long as it contains the shaped particles according to the present invention. However, in order to sufficiently obtain the effects of the present invention, the particles other than the present invention contained in the powder are preferably 5% or less.

The method for manufacturing a three-dimensional object according to the present embodiment includes the following steps (I) to (III) using water-insoluble structural material particles and support material particles having the structure shown in FIG. 1 as modeling particles. .

(I) The step of arranging the structural material particles and the support material particles to form a particle layer (II) The step of laminating the particle layers to form a shaped object (III) The support body included in the shaped object is water Removing by contacting with a solvent containing

By repeating the steps (I) and (II) and carrying out the step (III) on the shaped product obtained by laminating the required number of particle layers, the support body can be selectively removed, and the shaping is performed. A three-dimensional object that is an object can be obtained.

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 body required 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 body 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), when the thermal energy is applied and the particles are fused, 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.

As the thermoplastic material contained in the support material particles, inorganic materials, dietary fibers, carbohydrates such as carbohydrates, polyalkylene oxide, polyvinyl alcohol (PVA), and polyethylene glycol (PEG) are suitable. Specific examples of the water-soluble dietary fiber include polydextrose and inulin, and specific examples of the carbohydrate include sucrose, lactose, maltose, trehalose, melezitose, stachyose, and maltotetraose. A specific example of the polyalkylene oxide is polyethylene glycol (PEG).

The material constituting the structural material particles may be selected in accordance with the function required for the modeling object, and may include 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.

The method for forming the particle layer is not particularly limited, but a method in which the particle layer is arranged in units of lines or planes is preferable from the viewpoint of modeling speed. 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.

In the case of forming a particle layer containing a plurality of types of modeling particles as in this 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 of FIG. 1 according to the present invention are applied to an electrophotographic additive manufacturing method, charging attenuation, which is a problem of modeling particles containing a water-soluble material, is suppressed.

Since water-soluble materials are generally hydrophilic, the charge amount of 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 the present invention, in the process of forming the particle layer, the charge amount is attenuated and the molding particles cannot be arranged at a predetermined position. May occur. On the other hand, in the particles having the configuration shown in FIG. 1, 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 rate of decay α of the surface potential of the shaped particles is preferably less than 0.3, more preferably 0.2 or less, and even 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 the modeled object by stacking the particle layers The step of repeatedly stacking the particle layer obtained in the step (I) to obtain a modeled 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. For example, any of the following methods (i) to (iii) can be applied.

(I) Method of fusing modeling particles after laminating a plurality of particle layers As shown in (1) and (2) of FIG. A particle layer laminate 103 is obtained by laminating the particle layer laminate 102 composed of the formed particle layers. Next, when thermal energy is applied to the particle layer laminate 103, the shaped particles 100 are melted and fused to each other, and a shaped article 104 is obtained as shown in (3) of FIG.

(Ii) Method of fusing modeling particles each time a particle layer is laminated one layer As shown in (1) and (2) of FIG. At the same time as stacking on the shaped object 202 made of the created particle layer, thermal energy is applied to the layered surface of the particle layer 101 and the shaped object 202. Then, the modeling particles 100 are melted and fused together, and at the same time, the modeling object 202 is also fused, and as shown in (3) of FIG. 2B, a new modeling object including the particle layer 101 and the modeling object 202 is obtained. 104 is obtained. This method is preferable because the number of modeling particles in the particle layer to be melted at one time is smaller than (i), and voids are hardly generated in the modeled object 202.

(Iii) Method of fusing the shaped particles in the particle layer before laminating As shown in (1) and (2) of FIG. 2 (c), the core layer softening temperature or more is formed each time the particle layer 101 is formed. Thermal energy is applied so that the molding particles 100 are fused together to form a sheet. At the same time when the sheet-like particle layer 301 is laminated on the shaped article 202, thermal energy is applied to the laminated surface of the sheet-like particle layer 301 and the shaped article 202.

Then, the sheet-shaped particle layer 301 is fused to the modeled object 202, and a new modeled object 104 composed of the sheeted particle layer 301 and the modeled object 202 is obtained as shown in (3) of FIG. It is done. This method is also preferable because, as in (ii), voids are less likely to be generated inside the shaped article 202.

In the above (i) to (iii), the case where thermal energy is used for fusion between modeling particles has been described, but a method of chemically fusing using a chemical can also be used. 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 body contained in the modeled object by contacting with a solvent containing water The modeled object prepared by repeating the steps (I) and (II) as many times as necessary is used as 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 shaped object comes into contact with a solvent containing water, the water-soluble material contained in the support body dissolves. The shell debris contained in the support body is not easily dissolved because of its low solubility in water, but is removed from the structure together with the water-soluble material. Since the structure is made of a water-insoluble material, there is no fear of dissolving in a solvent containing water, and there is no fear that the shape will change due to the removal of the support body.

When the support body is removed by immersing the entire molded article in a solvent, it is preferable to add a water flow or ultrasonic vibration to the solvent because dissolution or disintegration of the support body is promoted.

The modeling particles according to the present invention have high moisture resistance in the particle state, and can be dissolved or disintegrated with water after the 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.

Existing techniques such as surface element analysis can be used as a technique for analyzing the main components of chemical species. 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), and the like can be used.

The above surface elemental analysis may be performed on the particles and the shaped 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 shell coverage 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, a ratio between 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 a 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.

The volume-based average particle diameter (hereinafter simply referred to as average particle diameter) of the modeling particles constituting the powder used in the modeling method is preferably 1 μm or more and 100 μm or less, more preferably 20 μm or more. 80 μm or less. 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 obtained using a commercially available particle size distribution measuring device. 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.

First, set the batch cell containing the measurement solvent in the measurement device, adjust the optical axis, and adjust the background. 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 is 90% to 95%, and the particle size distribution is measured. The volume-based average particle diameter can be calculated from the obtained measurement results.

In addition, 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 with the same area as the particle projection area) / (perimeter of the particle projection image)

The “particle projection area” is the area of the binarized particle image, and the “peripheral length of the particle projection 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.

<Modeling equipment>
Next, an apparatus suitable for modeling using the modeling particles according to the present invention will be described. For example, in the electrophotographic system, the modeling apparatus 500 shown in FIG. 7 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. FIG. 7 shows a configuration in the case where one type of each of the structural material particles and the support material particles is used, but 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.

The particle layer made of structural material particles and the particle layer made of support material particles are formed on different 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 in the middle of 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 is formed in which the part made of the structural material particles is the structural body 27a and the part made of the support material particles is the support body 27b. A modeling apparatus suitable for the electrophotographic system is not limited to the configuration shown in FIG.

It is preferable to combine 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 materials. 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 the modeling particle according to the present invention is used as the support material particle, the modeling apparatus includes at least a cartridge containing a powder containing structural material particles in the material container, and a powder containing the modeling particle according to the invention in the material container. The cartridge housing the body 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 mentioned above, when manufacturing a water-insoluble solid 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 of the present invention is limited to this. It is not something. For example, when a water-soluble three-dimensional object is manufactured by the additive manufacturing method, the modeling particle of the present invention is suitable as the structural material particle.

(Example)
Implementation of powders A to O containing modeling particles having a core and a shell according to the present invention, and powders P and Q containing particles not having a shell, and evaluating whether they are suitable as materials for modeling An example will be described.

First, after explaining the manufacturing method of the mother particles 1 to 4 used as a core for any of the modeling particles constituting the powders A to O, the manufacturing method of each powder will be described.

<Preparation of mother particle 1>
Cellulose (Cerish FD200L Daicel Finechem Co., Ltd.) was dissolved in 168 g of water by dissolving 89 g of maltotetraose powder (Nissan Fuji Oligo # 450, manufactured by Nippon Food & Chemicals Co., Ltd.) and 38 g of lactitol (produced by Lactitol LC-0, Food Science Co., Ltd.). After 113 g was dispersed, it was granulated with a spray dryer. The obtained powder was classified to obtain mother particles 1 having an average particle diameter of 23 μm. The volume ratio of the water-soluble substance in the particles is 85%, the solubility in water is 50 or more, and the softening temperature is 120 ° C. The average particle size was measured using a laser diffraction / scattering particle size distribution analyzer LA-950 (manufactured by HORIBA).

First, a batch type cell containing a measurement solvent is set in a laser diffraction / scattering particle size distribution measuring apparatus LA-950 (manufactured by HORIBA) to adjust the optical axis and the background. It is necessary to select a solvent that does not dissolve particles as the solvent used at this time. Here, isopropyl alcohol (special grade, manufactured by Kishida Chemical Co., Ltd.) was used.

The prepared powder was added to a batch cell until the transmittance of light emitted from the tungsten lamp reached 95% to 90%, and the particle size distribution was measured. From the obtained measurement result, the average particle diameter based on the volume of the particle A was calculated. For the other particles, the average particle size was measured in the same manner.

<Preparation of mother particle 2>
84 g of maltotetraose powder (Nissan Fujioligo # 450, manufactured by Nippon Food & Chemicals Co., Ltd.) and 36 g of lactitol (Lactitol LC-0, manufactured by Food Science Co., Ltd.) were dissolved in 107 g of water, and cellulose (Cerish FD200L Daicel Finechem Co., Ltd.) was used. After 113 g was dispersed, it was granulated with a spray dryer. The obtained powder was classified to obtain mother particles 2 having an average particle diameter of 23 μm. The volume ratio of the water-soluble substance in the particles is 80%, the solubility in water is 50 or more, and the softening temperature is 135 ° C.

<Preparation of mother particle 3>
Particles contained in the powder of maltotetraose (Eclipse Fujioligo # 450, manufactured by Nippon Shokuhin Kako Co., Ltd.) were used as mother particles 3. The average particle size is 88 μm. Maltotetraose particles are water-soluble materials, have a solubility in water of 50 or more, and a softening temperature of 160 ° C.

<Adjustment of mother particle 4>
A powder of maltotetraose (Eclipse Fuji Oligo # 450, manufactured by Nippon Shokuhin Kako Co., Ltd.) was kneaded and ground to obtain mother particles 4 having an average particle size of 85 μm. The solubility of the particles in water is 50 or more, and the softening temperature is 160 ° C.

<Preparation of powder A>
1.68 g of silicone resin (XC99-A8808, manufactured by Momentive Performance Materials Japan GK) and 335 g of powder consisting of mother particles 1 are combined into a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron) And stirred for 1 hour at a rotor load of 2 kW. Silicone resin is a water-insoluble material, and its solubility in water is 1 or less. The obtained powder was classified to obtain a powder A composed of particles having the base particle 1 as a core and a silicone resin as a shell.

<Preparation of powder B>
A powder B made of particles having the mother particle 2 as a core and a silicone resin as a shell is obtained in the same manner as the powder A, except that a powder made of the mother particle 2 is used instead of the powder made of the mother particle 1. It was.

<Preparation of powder C>
3.35 g of silicone resin (XC99-A8808, manufactured by Momentive Performance Materials Japan GK) and 335 g of powder consisting of mother particles 2 in a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron) The stirring process was performed for 1 hour at a rotor load of 2 kW. Silicone resin is a water-insoluble material. The obtained powder was classified to obtain a powder C composed of particles having the mother particle 2 as a core and a silicone resin as a shell.

<Preparation of powder D>
10.1 g of silicone resin (XC99-A8808, manufactured by Momentive Performance Materials Japan GK) and 335 g of powder composed of mother particles 2 are combined into a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron) And stirred for 1 hour at a rotor load of 2 kW. Silicone resin is a water-insoluble material. The obtained powder was classified to obtain a powder D composed of particles having the mother particle 2 as a core and a silicone resin as a shell.

<Preparation of powder E>
Polystyrene resin (PSJ-polystyrene HF77 manufactured by PS Japan Ltd.) was dissolved in toluene to prepare a 0.5% solution. Polystyrene resin is a water-insoluble material, and its solubility in water is 1 or less. The process of spraying the solution and drying toluene while heating and flowing 700 g of the powder composed of the mother particles 1 was performed until the total amount of spray liquid reached 1400 g. Thereafter, the obtained powder was classified to obtain a powder E composed of particles having a base particle 1 as a core and a polystyrene resin as a shell.

<Preparation of powder F>
Polystyrene resin (PSJ-polystyrene HF77 manufactured by PS Japan Ltd.) was dissolved in toluene to prepare a 7.5% solution. Polystyrene resin is a water-insoluble material. The step of spraying the solution and drying toluene while stirring 300 g of the powder composed of the mother particles 1 was carried out until the total amount of the spray liquid reached 40 g, and then the obtained powder was classified to obtain the mother particles 1 A powder F comprising particles having a core and polystyrene resin as a shell was obtained.

<Preparation of powder G>
Polystyrene resin (PSJ-polystyrene HF77 manufactured by PS Japan Ltd.) was dissolved in toluene to prepare a 7.5% solution. Polystyrene resin is a water-insoluble material. The step of spraying the solution and drying toluene while stirring 300 g of the powder composed of the mother particles 1 was performed until the total amount of the spray liquid reached 120 g, and then the obtained powder was classified to obtain the mother particles 1 A powder G composed of particles having a core and polystyrene resin as a shell was obtained.

<Preparation of powder H>
3.35 g of styrene acrylic resin (MP-5000, manufactured by Soken Chemical Co., Ltd.) and 335 g of powder consisting of mother particles 1 are put into a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron) and loaded with a rotor. Stirring was performed at 2 kW for 30 minutes. The obtained powder H is composed of particles having the mother particle 1 as a core and a styrene acrylic resin as a shell. Styrene acrylic resin is a water-insoluble material, and its solubility in water is 1 or less.

<Preparation of powder I>
6.70 g of styrene acrylic resin (MP-5000, manufactured by Soken Chemical Co., Ltd.) and 335 g of powder consisting of mother particles 1 are charged into a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron Corporation) and loaded with a rotor. Stirring was performed at 2 kW for 30 minutes. The obtained powder I is composed of particles having the base particle 1 as a core and a styrene acrylic resin as a shell.

<Preparation of powder J>
13.4 g of styrene acrylic resin (MP-5000, manufactured by Soken Chemical Co., Ltd.) and 335 g of powder composed of mother particles 1 are charged into a dry particle compounding device (Nobilta NOB-130, manufactured by Hosokawa Micron Corporation) and loaded with a rotor. Stirring was performed at 2 kW for 30 minutes. The obtained powder J is composed of particles having the mother particle 1 as a core and a styrene acrylic resin as a shell.

<Preparation of powder K>
20 g of sucrose behenic acid ester (Ryoto Sugar Ester B370f manufactured by Mitsubishi Chemical Foods Co., Ltd.) was dispersed and stirred in 1000 g of ethanol (special grade Kishida Chemical Co., Ltd.), and the temperature was raised to 80 ° C. Note that sucrose behenic acid ester is a water-insoluble material, and its solubility in water is 1 or less.

200 g of powder consisting of mother particles 1 was added to the above solution and mixed. After 5 minutes, the temperature dropped to 60 ° C. over 20 minutes. Then, after cooling to room temperature, it filtered and dried, crushing.

The obtained powder was classified to obtain a powder K composed of particles having the mother particle 1 as a core and sucrose behenate as a shell.

<Preparation of powder L>
Except for the amount of sucrose behenic acid ester added being 70 g, a powder L consisting of particles having the mother particle 1 as a core and the sucrose behenic acid ester as a shell was obtained in the same manner as the powder K adjustment method.

<Preparation of powder M>
A powder comprising particles having the mother particle 1 as a core and sucrose behenate as a shell in the same manner as the powder K, except that the amount of sucrose behenate added is 20 g and the amount of ethanol is 2000 g. Body M was obtained.

<Preparation of particles N>
In the same manner as the preparation method of powder K, except that powder consisting of mother particles 3 is used instead of powder consisting of mother particles 1, particles having core particles 3 as a core and sucrose behenate as a shell are used. A powder N was obtained.

<Preparation of powder O>
In the same manner as the preparation method for powder K, except that powder consisting of mother particles 4 is used instead of powder consisting of mother particles 1, particles having core particles 4 as a core and sucrose behenate as a shell are used. A powder O was obtained.

<Preparation of powder P>
The powder composed of the mother particles 1 was designated as powder P.

<Preparation of powder Q>
The powder composed of the mother particles 2 was designated as powder Q.

For each of the powders A to Q obtained by the above method, the average particle diameter, average circularity, and coverage were determined. The results are summarized in Table 1. In addition, the addition amount of the shell material in Table 1 is a value obtained by converting the addition amount of the core material into 100 g.

<Examples 1 to 15 and Comparative Examples 1 and 2>
As examples, the following evaluations were performed on the obtained powders A to O. Further, the same evaluation was performed on the powders P and Q as Comparative Examples 1 and 2.

(Evaluation of change in fluidity of powder)
1.00 g of each powder maintaining the state immediately after production is weighed and placed on a sieve having a mesh size 5 to 7 times the average particle size, and is vibrated for 10 seconds at a frequency of 100 times per second. After that, the weight of the powder remaining on the mesh was measured. By using a sieve having a mesh size 5 to 7 times the average particle size, it is possible to suppress the influence of electrostatic aggregation of particles and determine the degree of aggregation or fusion due to humidity of the particles.

Next, 2.0 g of each powder maintaining the state immediately after production is put in a 100 ml polycup, placed in a hermetic bag, and left in an environmental test machine at 25 ° C. and 55% humidity, so that the powder is environmental. I waited until I got used to the temperature. By this step, it is possible to eliminate the influence of condensation due to a rapid temperature change. After 15 minutes, the bag was opened and the polycup was allowed to stand in the above environment for 7 hours, and then the entire polycup was taken out of the environmental testing machine. The temperature / humidity condition is a maximum humidity environment recommended for general 3D printers.

Thereafter, the fluidity of the powder after standing was evaluated in the same manner as before standing in an environmental test machine, and the weight change of the powder remaining on the mesh before and after standing was calculated and ranked. The evaluation criteria for each rank are as follows.

Rank A Weight change is less than 5% Rank B Weight change is greater than 5% and less than 20% Rank C Weight change is greater than 20% and less than 90% Rank D Weight change is greater than 90%

The powder of rank A was excellent in the fluidity of the powder after standing. In rank B, particles were agglomerated or fused at a very small part of the powder after standing, and the fluidity of the powder was reduced. In rank C, particles were agglomerated or fused in part of the powder after standing, and the fluidity of the powder was reduced. In rank D, more than half of the powder particles aggregated or fused after standing, and the fluidity of the powder was significantly reduced.

Fig. 4 shows a micrograph of the powder determined to be Rank A after standing.

When using a powder determined to be rank D, the fluidity of the powder decreases due to exposure to a long time in a humidity environment. There arise problems such as uniformity and defects in the particle layer. In particular, even when the aggregation is significant, even lamination may not be possible.

FIG. 5 shows a micrograph of the powder determined to be rank D after standing. In the powders P and Q, agglomeration and fusion between the particles proceeded to form an aggregated aggregate.
In the case of modeling using powders determined to be ranks A and B, no major problems occur in actual use, but the powders of rank A are particularly excellent in stability under humidity environment, and have a uniform thickness and Since a particle layer having a high density can be formed, it is possible to produce a particularly high-precision shaped article.

(Evaluation of volume change by water)
The produced powder is placed on the base so that the applied amount is 1.5 to 2.5 mg / cm 2, and a particle layer is produced. Next, a sheet was formed by heating at a temperature equal to or higher than the softening temperature of the particles. The obtained sheets were stacked and the process of thermocompression bonding by applying a pressure of 0.01 kgf / cm2 or more above the softening temperature of the particles was repeated to produce a shaped article having a thickness of about 1 mm.

The obtained model was exposed to flowing water at 3000 ml / min for 300 minutes, and the volume change due to water was evaluated according to the following criteria.

In addition, the volume change was measured using a known volume measurement method. When the modeled object collapsed, the modeled volume of the largest volume was measured, and the change from the initial volume was calculated.

Table 2 shows the results of each evaluation.

Rank A Volume change is 90% or more Rank B Volume change is 5% or more and less than 90% Rank C Volume change is less than 5%

When a laminate was prepared using the powder of rank A and rank B, it can be removed with water, and in particular, the powder of rank A can be easily removed.

(Laminate void evaluation)
The produced powder is placed on the base so that the applied amount is 1.5 to 2.5 mg / cm 2, and a particle layer is produced. Next, a sheet was formed by heating at a temperature equal to or higher than the softening temperature of the particles. The obtained sheets were stacked and the process of thermocompression bonding by applying a pressure of 0.01 kgf / cm 2 or more above the softening temperature of the particles was repeated to produce a shaped article having a thickness of about 5 mm.

The voids were evaluated by observing the cross section in the laminate with a scanning electron microscope (SEM) according to the following criteria for the obtained shaped article.

Rank A There are voids in the laminate Rank B There are significant voids in the laminate

<Examples 16 to 21>
Further, as examples, the following evaluations were performed on the powders E to J.

(Evaluation of removal rate with water)
The produced powder is placed on the base in a circular shape with a radius of 15 mm so that the applied amount is 1.5 to 2.5 mg / cm 2 to produce a particle layer. Next, a sheet was formed by heating at a temperature equal to or higher than the softening temperature of the particles. The obtained sheets were stacked, and the process of thermocompression bonding by applying a pressure of 0.01 kgf / cm2 or more above the softening temperature of the particles was repeated to produce a shaped article having a thickness of 2 to 3 mm.

The obtained model was exposed to flowing water of 3000 ml / min for 60 minutes, and the removal rate (mm / hr) of the circular model was calculated from the volume change of the model and evaluated according to the following criteria.

In addition, the volume change was measured using a known volume measurement method. When the modeled object collapsed, the modeled volume of the largest volume was measured, and the change from the initial volume was calculated.

Table 3 shows the results of each evaluation.

Rank A removal rate is 0.15 mm / hr or higher Rank B removal rate is less than 0.15 mm / hr

A shaped object made of powder of rank A can be used more suitably as a support material used in a structure that supports a columnar structure because a column with a thickness of 0.3 mm can be removed with water in less than 1 hour. it can.

From the above examples, the powders A to O according to the present invention are powders and have excellent moisture resistance, but they can be disintegrated by contact with water, and the shape can be easily broken. It was confirmed that the molded particles were suitable for the production of On the other hand, although the powders P and Q used as comparative examples were excellent in solubility in water, they were inferior in moisture resistance, and the aggregation or fusion of particles was remarkable. A micrograph showing the state of the powder P fused by the evaluation of the change in fluidity of the powder is shown in FIG.

<Examples 22 to 31, Comparative Example 3>
Furthermore, the following evaluation was performed about powder A thru | or J as an Example. Further, as a comparative example, the same evaluation was performed on the powder P.

(Evaluation of charge retention)
The charge retention was evaluated by the following method.

A measurement method based on Japanese Industrial Standards JIS C61340-2-1 was carried out using a charge attenuation device (NS-D100 type, manufactured by Nano Seeds).

Specifically, a charge was applied to the powder composed of particles measured by corona discharge, and the change in potential with time of the powder was measured with a surface potential meter. The measurement conditions were applied voltage: −600 V, application time: 1 second, measurement time: 600 seconds, measurement environment: 25 ° C., 45-50% RH (indoor environment).

Measure the potential every time, substitute it into the logarithm of both sides of Formula 1, graph it, extract the range of the part that can be linearly approximated the longest in the graph, and calculate the decay rate α.

V = V0exp (−α√t) (Formula 1)
V: Surface potential V0: Initial surface potential t: Decay time α: Decay rate

As an example, a measured value of potential for each time for powder I and powder P and a graph of charge decay obtained from Equation 1 are shown in FIG. 6 together with an approximate straight line.

(Evaluation of adaptability to electrophotography)
The electrophotographic adaptability was evaluated by the following method.

The toner in the commercially available electrophotographic CRG was removed, filled with powder, and the developed powder on the electrostatic latent image bearing member was transferred to the transfer member using electrostatic force. The transfer efficiency was calculated from the ratio of the amount of powder on the electrostatic latent image carrier and the amount of powder after transfer to the transfer body.

Based on the obtained transfer efficiency, the electrophotographic adaptability was evaluated according to the following criteria.

Rank A Transfer efficiency is 90% or more Rank B Transfer efficiency is 70% or more and less than 90% Rank C Transfer efficiency is less than 70%

In the powder of rank A, there are few missing parts in the particle layer, and when the particle layer is laminated, the problem of poor lamination due to the lamination on the missing part of the particle layer hardly occurs. Therefore, it can be suitably used for an electrophotographic system. In the powder of rank C, there are many missing portions in the particle layer, and poor stacking frequently occurs.

Table 4 shows the decay rate α as a result of the evaluation of the charge retention of the powders A to J and the powder P, and the evaluation result of the electrophotographic adaptability.

Therefore, the powders A to J have an effect on the charge amount attenuation as compared with the powder P, and can be suitably used in the electrophotographic system.

A three-dimensional structure was prepared by electrophotography using particles L as support material particles and powder particles obtained by pulverizing ABS (Techno ABS130 manufactured by Techno Polymer Co., Ltd.) as structural material particles.

By using the apparatus shown in FIG. 7, a particle layer having a pattern composed of two types of particles of structural material particles and support material particles is formed and laminated to form a modeled object in which the structural material portion and the support material portion exist. Produced.

The modeled part (support body) formed by the particles L was easily removed by exposing the resulting modeled object to running water, and the target three-dimensional object composed of ABS could be obtained.

The present invention is not limited to the above embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

This application claims priority on the basis of Japanese patent application Japanese Patent Application No. 2014-194014 filed on September 24, 2014 and Japanese Patent Application No. 2015-178950 filed on September 10, 2015. All the descriptions are incorporated herein.

DESCRIPTION OF SYMBOLS 11 Shell 12 Core 100 Modeling particle 101 Particle layer 102, 103 Particle layer laminated body 104, 202 Modeling object 301 Sheeted particle layer 500 Modeling apparatus 501 Particle layer formation part 502 Modeling part 21a, 21b Material supply part 22a, 22b Photoconductor 23a, 23b Laser beam 24 Transfer body 25 Stage 26 Opposing member 27a Structure 27b Support body

Claims (28)

1. Modeling particles containing a water-soluble material,
   A core and a shell covering at least a part of the surface of the core;
   The core contains the most water-soluble material,
   The shaped particles characterized in that the water-soluble material contained most in the shell has a lower solubility in water than the water-soluble material contained in the core.
2. The shaped particle according to claim 1, wherein the coverage of the shell on the surface of the core is 40% or more.
3. 3. The shaped particle according to claim 1, wherein the covering ratio of the shell to the surface of the core is 95% or less.
4. The shaped particle according to any one of claims 1 to 3, wherein the shaped particle contains a water-soluble substance having a volume ratio of 70% or more.
5. The shaped particle according to any one of claims 1 to 4, wherein a ratio of a volume of the core to a volume of the particle is 50% or more.
6. The shaped particle according to any one of claims 1 to 5, wherein a volume ratio of the water-soluble material contained in the core to the entire core is 50% or more.
7. The shaped particle according to any one of claims 1 to 6, wherein a volume ratio of a material most contained in the shell to the entire shell is 50% or more.
8. The water-soluble material contained in the core is any one of a water-soluble inorganic material, a water-soluble carbohydrate, polyalkylene oxide, polyvinyl alcohol, and polyethylene glycol. The shaped particle according to item.
9. The shaped particle according to any one of claims 1 to 8, wherein the material most contained in the shell is an organic substance, a metal, an inorganic substance, or an organic / inorganic composite material.
10. The shaped particle according to claim 9, wherein the organic / inorganic composite material is a compound having a siloxane bond as a main skeleton and a side chain composed of an organic group.
11. The shaped particle according to claim 10, wherein the side chain composed of the organic group is a methyl group.
12. The shaped particle according to any one of claims 1 to 11, wherein the solubility of the water-soluble material contained in the core in water is greater than 1.
13. The modeling particle according to any one of claims 1 to 12, wherein the solubility of the material most contained in the shell in water is smaller than 10.
14. The shaped particles according to any one of claims 1 to 13, wherein main components of the core and the shell are different from each other.
15. The water-soluble material contained in the core includes a plurality of types, and the solubility of water in the material most contained in the shell is smaller than the solubility in water of any water-soluble material contained in the core. Item 15. The shaped particle according to any one of Items 1 to 14.
16. The shaped particle according to any one of claims 1 to 15, wherein the core or the shell contains a thermoplastic material.
17. The modeling particle according to any one of claims 1 to 16, wherein the water-soluble material contained in the core is a thermoplastic material.
18. 18. The shaped particle according to claim 1, wherein the volume-based average particle diameter is 1 μm or more and 100 μm or less.
19. The shaped particle according to any one of claims 1 to 18, wherein the average circularity is 0.85 or more.
20. The shaped particle according to any one of claims 1 to 19, wherein the charge decay rate α is less than 0.3.
21. The shaped particle according to any one of Claims 1 to 20, wherein the shell has a volume resistivity greater than 10 ^-3 Ω · cm.
22. A powder containing the shaped particles according to any one of claims 1 to 21.
23. When passing through a sieve having a mesh size 5 to 7 times the average particle size between the powder immediately after production and the powder after standing for 7 hours in an environment of 25 ° C. and 55% humidity The powder according to claim 21, wherein the weight change of the material remaining on the mesh is 20% or less.
24. The powder according to claim 23, wherein the weight change is 5% or less.
25. A manufacturing method of a three-dimensional object,
    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 method for producing a three-dimensional object according to any one of claims 1 to 21, wherein the shaped particles according to any one of claims 1 to 21 are used as the support material particles.
26. The step of forming the particle layer is a step of forming a particle layer on the transfer body,
    A step of transferring one of the structural material particles and the support material particles to the transfer body, and a step of transferring the particle layer having the other particles to the transfer body. The method for producing a three-dimensional object according to claim 25.
27. 27. The method for producing a three-dimensional object according to claim 26, wherein the transfer of the particle layer to the transfer body is performed using an electrostatic force.
28. 28. The step of laminating the particle layer to form a shaped object is a step of laminating the particle layer by applying thermal energy to the three-dimensional object according to any one of claims 25 to 27. Production method.

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