JP2017193090A - Powder material, manufacturing method of powder material, manufacturing method of solid molded article and solid molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder material for a powder bed melting coupling method containing composite particles and capable of manufacturing higher definition solid molded article.SOLUTION: There is related a powder material used for manufacturing a solid molded article by irradiating a laser light selectively to a power material containing composite particles to form a molded article layer where the composite particles are burned or melting bond and laminating the molded article layer. The composite particles contain base particles containing a thermoplastic resin with average particle diameter of 1 μm to 100 μm and sub particles containing metal oxide fastened to a surface of the base particles and having lower volume resistance than the thermoplastic resin. The powder material contains the metal oxide of 0.5 pts.mass to 10 pts.mass based on 100 pts.mass of the thermoplastic resin. Residual ratio of the metal oxide after the powder material is applied to an ultrasonic dispersion treatment in water to the powder material is 20 mass% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a powder material, a method for producing a powder material, a method for producing a three-dimensional model, and a three-dimensional model apparatus.

  In recent years, various methods have been developed that can relatively easily manufacture a three-dimensional object having a complicated shape. As one of methods for producing a three-dimensional structure, a powder bed fusion bonding method is known. The powder bed fusion bonding method is characterized by high modeling accuracy and high adhesion strength between laminated layers. Therefore, the powder bed fusion bonding method can be used not only for manufacturing a prototype for confirming the shape or properties of the final product, but also for manufacturing the final product.

  In the powder bed fusion bonding method, a powder material containing particles containing resin material or metal material is laid flat to form a thin film, and a laser is irradiated to a desired position on the thin film to select particles contained in the powder material. Sintered or melted and bonded (hereinafter, the bonding of particles by sintering or melting is also simply referred to as “melt bonding”), thereby finely dividing the three-dimensional object in the thickness direction (hereinafter referred to as “melt bonding”) , Simply referred to as “modeled object layer”). A powder material is further spread on the layer thus formed, and laser irradiation is performed to selectively melt bond particles contained in the powder material, thereby forming the next modeled object layer. By repeating this procedure and stacking the modeling object layers, a three-dimensional modeling object having a desired shape is manufactured.

  Patent Document 1 discloses a powder containing mother particles made of a thermoplastic resin and child particles made of silica, titania, alumina, or the like that have an anti-aggregation effect by covering at least a part of the surface of the microsphere. The powder material used in the bed melt bonding method is described. According to Patent Document 1, since the powder material has low agglomeration property, the fluidity is high, and the packing density when forming a thin layer can be increased. Therefore, the accuracy and strength of the three-dimensional structure can be increased. Have been described.

JP 2006-321711 A

  In Patent Document 1, when at least a part of the surface of a microsphere made of a thermoplastic resin is coated with silica, titania, alumina, or the like, the packing density of the thin layer is increased and the accuracy of the three-dimensional structure is increased. It is stated that you can. However, as the three-dimensional modeling becomes widespread, the accuracy required for the three-dimensional model has increased, and there is still room for improvement in order to produce a higher-definition three-dimensional model.

  The present invention has been made in view of the above problems, and is a powder material for a powder bed fusion bonding method including composite particles containing resin particles and mother particles, and a finer three-dimensional powder material. The object is to provide a powder material capable of producing a shaped article. The present invention further provides a method for manufacturing such a powder material, a method for manufacturing a three-dimensional object using such a powder material, and a three-dimensional object manufacturing apparatus capable of manufacturing a three-dimensional object using such a powder material. The purpose is to provide

The present invention relates to the following powder material, a method for producing a powder material, a method for producing a three-dimensional object, and a device for producing a three-dimensional object.
[1] A thin layer of a powder material containing composite particles is selectively irradiated with laser light to form a shaped article layer formed by sintering or melt bonding the composite particles, and the shaped article layer is laminated. The composite material is a powder material used for manufacturing a three-dimensional model according to the invention, wherein the composite particles are fixed on the surface of the mother particles and mother particles containing a thermoplastic resin having an average particle diameter of 1 μm or more and 100 μm or less. Child particles containing a metal oxide having a volume resistivity lower than that of a plastic resin, and the powder material is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. A powder material containing an oxide, wherein a residual ratio of the metal oxide after ultrasonic dispersion treatment of the powder material in water with respect to the powder material is 20% by mass or more.
[2] The powder material according to [1], wherein the average particle diameter of the child particles is 10 nm or more and 500 nm or less.
[3] The powder material according to [1] or [2], wherein a volume resistance value of the metal oxide is 1/10 or less of a volume resistance value of the thermoplastic resin.
[4] The powder material according to [1] or [2], wherein a volume resistance value of the metal oxide is 1/100 or less of a volume resistance value of the thermoplastic resin.
[5] The powder material according to any one of [1] to [4], wherein the average particle diameter of the mother particles is 5 μm or more and 70 μm or less.
[6] The powder material according to any one of [1] to [5], wherein the residual ratio of the metal oxide is 30% by mass or more.
[7] A thin layer of powder material containing composite particles is selectively irradiated with laser light to form a shaped article layer formed by sintering or melting and bonding the composite particles, and the shaped article layer is laminated. And a metal oxide having a volume resistivity lower than that of the thermoplastic resin. And a step of mixing and stirring with a mixing device at a mass ratio such that the amount of the metal oxide with respect to 100 parts by mass of the thermoplastic resin is 0.5 parts by mass or more and 10 parts by mass or less. ,Production method.
[8] The production method according to [7], wherein in the mixing and stirring step, fine particles containing the metal oxide having an average particle size of 10 nm to 500 nm are used.
[9] A step of forming a thin layer of the powder material according to any one of [1] to [6] or the powder material produced by the production method according to [7] or [8], and the formed A step of selectively irradiating a thin layer with laser light to form a shaped article layer formed by sintering or melting and bonding composite particles contained in the powder material; a step of forming the thin layer; and the shaping The manufacturing method of the three-dimensional molded item including the process of forming a physical layer, repeating the process several times in this order, and laminating the said molded article layer.
[10] A modeling stage and a thin film of the powder material according to any one of [1] to [6] or the powder material manufactured by the manufacturing method according to [7] or [8] are formed on the modeling stage. A thin film forming section, a laser irradiation section for irradiating the thin film with a laser to form a shaped article layer in which the particles are sintered or melt-bonded, and the modeling stage, the position in the vertical direction being variable. A three-dimensional modeling apparatus comprising: a stage support unit to be supported; and a control unit that controls the thin film forming unit, the laser irradiation unit, and the stage support unit to repeatedly form and stack the modeled object layer.

  According to the present invention, a powder material for powder bed fusion bonding method including composite particles, which can produce a finer three-dimensional structure, a method for producing such a powder material, and such a powder material There are provided a method for manufacturing a three-dimensional object using the three-dimensional object, and a three-dimensional object manufacturing apparatus capable of manufacturing a three-dimensional object using such a powder material.

FIG. 1 is a diagram schematically showing the configuration of a powder material in one embodiment of the present invention. FIG. 2 is a diagram showing the flow of each step of the method for producing a powder material in one embodiment of the present invention. FIG. 3 is a side view schematically showing the configuration of the three-dimensional modeling apparatus in one embodiment of the present invention. FIG. 4 is a diagram showing the main part of the control system of the three-dimensional modeling apparatus in one embodiment of the present invention.

  In order to solve the above-mentioned problems, the present inventors diligently studied and experimented on a powder material capable of producing a three-dimensional structure by a powder bed fusion bonding method. As a result, the inventors have increased the fluidity of the powder material, and the particles are charged by the charge generated by friction between the particles and the modeling stage, friction between the plurality of particles, and the like. It was found that electrical repulsion is likely to occur. This electric repulsion tends to cause a gap between particles when forming a thin layer, and hinders close packing of particles. Based on this knowledge, the present inventors have studied the method of packing particles more densely when forming a thin film by making the particles difficult to be charged, and completed the present invention.

  The powder material according to an embodiment of the present invention includes composite particles in which child particles are fixed to the surface of mother particles including a thermoplastic resin. The child particles contain a metal oxide having a volume resistivity lower than that of the thermoplastic resin constituting the mother particles. By adopting such a configuration, the charge generated by the friction or the like is easily released from the mother particle to the outside of the composite particle through the child particle containing the metal oxide having a lower volume resistance value. Is considered to become more difficult to be charged.

  In addition, although the powder material containing a resin-made mother particle and child particles, such as a silica, is described also in patent document 1, according to the further new knowledge of the present inventors, in patent document 1, in the flow of a particle | grain, The emphasis is on improving the properties and electrostatic repulsion between particles is not considered. In addition, as described in Patent Document 1 or the like, if a bag containing particles containing thermoplastic resin and fine particles containing metal oxide is simply shaken, fine particles containing metal oxide (hereinafter referred to as mother particles) The fine particles that are not fixed (including the fine particles before fixing) may be simply referred to as “fine particles”) cannot be sufficiently fixed to the mother particles (particles including the thermoplastic resin). Therefore, a large amount of fine particles that could not be attached to the mother particles are present in the powder material produced by simply shaking. The fine particles present in a free state have a function of reducing the rolling resistance of the composite particles and assisting the relative movement between the composite particles and the modeling stage and the relative movement between the plurality of composite particles. Therefore, if the released fine particles are present in a large amount in the powder material, the composite particles easily move, and the composite particles are likely to be charged due to friction between the particles and the modeling stage or friction between a plurality of particles. Conceivable.

  On the other hand, when producing a powder material containing composite particles, the amount of the released fine particles can be reduced by fixing the fine particles containing a metal oxide more firmly to the mother particles, and therefore by friction. It is considered that charging of the composite particles can be suppressed and the composite particles can be packed more densely. Since the released fine particles are usually nano-sized fine particles, it is difficult to separate and quantify only the free fine particles from the powder material. However, according to the above method, the number of free fine particles is reduced. Can be reduced. Based on the above difficulty of removal, it is possible to estimate the amount of fine particles containing a metal oxide used in producing a powder material by measuring the content of the metal oxide in the powder material. Conceivable.

  The said powder material is 20 mass% or more with respect to the mass of the powder material before a process for the residual rate of the said metal oxide after carrying out the ultrasonic dispersion process on the conditions mentioned later. When the powder material is produced, if the mother particles and the fine particles are firmly fixed to such an extent that the residual ratio becomes 20% by mass or more, the fine particles existing in the powder material without being fixed to the mother particles. The number becomes smaller, and the charging of the composite particles derived from the released fine particles can be sufficiently suppressed. Therefore, it is considered that the powder material having the residual rate of 20% by mass or more can be more densely packed with composite particles when forming a thin layer. When three-dimensional modeling is performed by the powder bed fusion bonding method using such a powder material, it is more accurate because defects of a modeled object caused by a gap generated without filling particles in a thin layer are less likely to occur. And it is thought that it becomes possible to manufacture a three-dimensional molded item with stronger strength.

  When the present inventors confirmed, in order to produce the powder material whose said residual rate is 20 mass% or more, it is necessary to mechanically stir both. On the other hand, as described in Patent Document 1, if the bag containing the particles containing the thermoplastic resin and the fine particles containing the metal oxide is simply shaken, the residual rate is less than 20% by mass, Therefore, compared with the powder material which concerns on one Embodiment of this invention, the precision of a three-dimensional molded item does not fully improve. This is because the powder material produced only by stirring by shaking contains a large amount of fine particles that could not be fixed to the mother particles, so that the composite particles are easily charged by the friction, and the composite particles are packed closely. This is thought to be due to the lack of space.

  Hereinafter, representative embodiments of the present invention will be described in detail.

1. Powder Material In this embodiment, a thin layer of a powder material containing composite particles is selectively irradiated with laser light to form a modeled object layer formed by fusion bonding of the composite particles, and the modeled object layer is laminated. This relates to a powder material (hereinafter also simply referred to as “powder material”) used for manufacturing a three-dimensional structure. The composite particles include mother particles containing a thermoplastic resin and child particles containing a metal oxide fixed to the surface of the mother particles. Moreover, the said powder material contains the said metal oxide of 0.5 to 10 mass parts with respect to 100 mass parts of said thermoplastic resins. Moreover, the residual rate of the said metal oxide after ultrasonically dispersing the said powder material in water is 20 mass% or more with respect to the powder material before a process. The above powder material does not significantly interfere with the fusion bonding by laser irradiation and the dense filling of the composite particles when forming a thin layer, and does not significantly reduce the accuracy of the three-dimensional structure, such as a laser absorbent or a flow agent. In addition to the above mother particles and child particles fixed to the mother particles, materials and particles may be further included.

1-1. Composite particles The powder material is, as the composite particles, mother particles containing a thermoplastic resin, child particles containing a metal oxide fixed to the surface of the mother particles and having a lower volume resistivity than the thermoplastic resin, including. FIG. 1 schematically shows a powder material 10 including mother particles 11 and child particles 12.

  The thermoplastic resin that can be included in the mother particles only needs to be softened and melted by heating. Examples of the thermoplastic resin include polyethylene, polypropylene, nylon (such as nylon 6 and nylon 12), polyacetal, polyethylene terephthalate (PET), polyphenyl sulfide (PPS), polyether ether ketone (PEEK), and crystalline polyester. Crystalline resins including, polystyrene, polyurethane, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer (ABS), acrylic polymer, polycarbonate, ethylene-vinyl acetate copolymer (EVA), styrene-acrylonitrile copolymer (SAN), polyarylate And amorphous resins containing polyphenylene ether and polycaprolactone. The mother particles may contain only one type of thermoplastic resin or a combination of two or more types of thermoplastic resins. In addition, the powder material may include only one type of composite particles having the same thermoplastic resin constituting the mother particles, or two or more types of composite particles having different types of thermoplastic resins constituting the mother particles. It may be included in combination.

  It is preferable that the mother particle is substantially composed only of the thermoplastic resin. However, as long as the three-dimensional structure can have desired characteristics, a residue of a component used when the mother particle is manufactured, and the like Components other than the thermoplastic resin may be included.

  The average particle diameter of the mother particles is 1 μm or more and 100 μm or less. When the average particle size is 1 μm or more, the fluidity of the powder material is sufficiently increased, and the powder material can be easily handled when manufacturing a three-dimensional structure. Further, when the average particle diameter is 1 μm or more, it is easy to produce the mother particles, and the production cost of the powder material does not increase. When the average particle diameter is 100 μm or less, it is possible to produce a three-dimensional model with relatively high definition. From the viewpoint of easier handling of the powder material, easier production of the particles, and higher accuracy of the three-dimensional structure, the average particle diameter of the mother particles is more preferably 5 μm or more and 70 μm or less. More preferably, it is 20 μm or more and 60 μm or less. From the viewpoint of further increasing the accuracy of the three-dimensional structure, the upper limit of the average particle diameter of the mother particles is preferably 50 μm, more preferably 40 μm, and even more preferably 30 μm.

  In the present specification, the average particle diameter of the particles means the number average particle diameter measured by a dynamic light scattering method. The volume average particle diameter can be measured by, for example, a laser diffraction particle size distribution measuring apparatus (manufactured by SYMPATEC, HELOS) equipped with a wet disperser. In addition, the particle diameter of 100 particles arbitrarily selected from a microscope image of a resin imaged by a scanning electron microscope (SEM) or a transmission electron microscope (TEM) is measured, and the average value is the average particle diameter of the particles. It is good.

  The metal oxide contained in the child particles only needs to have a lower volume resistivity than the resin selected as the material of the thermoplastic resin. Examples of the metal oxide include silica, titanium oxide, metatitanic acid, alumina, zirconia, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, and manganese oxide. The child particles may contain only one type of metal oxide or a combination of two or more types of metal oxides. In addition, the powder material may include only one type of composite particles having the same metal oxide constituting the child particles, or two or more types of composite particles having different types of metal oxides constituting the child particles. It may be included in combination. When the child particles contain two or more kinds of metal oxides, it is preferable that the volume resistance value of any metal oxide is smaller than the volume resistance value of the thermoplastic resin contained in the mother particles.

  It is preferable that the child particles are substantially composed of only the metal oxide. However, as long as the three-dimensional structure can have desired characteristics, residues of components used when the child particles are manufactured, and the like Components other than the metal oxide may be included.

  From the viewpoint of making the composite particles more difficult to be charged, the difference in volume resistivity between the thermoplastic resin and the metal oxide is preferably large. From the above viewpoint, the volume resistivity of the metal oxide is preferably 1/10 or less and more preferably 1/100 or less of the volume resistivity of the thermoplastic resin.

  In this specification, the volume resistivity of a thermoplastic resin and a metal oxide can be made into the value measured, for example with the following method. However, if there is a known value or a value published by the manufacturer for each material, that value may be adopted.

(Example of volume resistivity measurement method)
The powdery material is molded into a 9 cm × 9 cm × 5 cm cylindrical shape by applying a pressure of 3 t. The volume resistivity of the cylindrical material is measured with a Hirester UX MCP-HT800 manufactured by Mitsubishi Chemical Analytech.

  The average particle diameter of the child particles may be such that it can achieve the above-mentioned residual rate and does not significantly impair the fluidity of the powder material, and can be, for example, 10 nm or more and 500 nm or less. When the average particle diameter is 10 nm or more, it is easier to produce the child particles, and the production cost of the powder material does not increase. When the average particle diameter is 500 nm or less, the fixing strength to the mother particles can be easily increased, and the residual rate can be easily achieved. In addition, when the average particle diameter is 500 nm or less, the shape of the composite particles can be made closer to a sphere, so that the fluidity of the powder material is not easily lowered. From the viewpoint of further increasing the fixing strength to the mother particles, the average particle diameter of the child particles is preferably smaller, for example, preferably 10 nm or more and 100 nm or less, and more preferably 10 nm or more and 55 nm or less. In the present specification, in the image obtained by imaging the cross section of a large number of composite particles with a transmission electron microscope (TEM), for 10 resin particles randomly selected, the particle size of the child particles is measured, The average value thereof is defined as the average particle diameter of the child particles included in the composite particles.

  The powder material contains 0.5 to 10 parts by mass of the metal oxide with respect to 100 parts by mass of the thermoplastic resin. When the content is 0.5 parts by mass or more, the composite particles can be made more difficult to be charged and the modeling accuracy of the three-dimensional model can be further increased. When the content is 10 parts by mass or less, fine particles that cannot be fixed to the mother particles at the time of producing the powder material are likely to be free and exist, and the accuracy of the three-dimensional structure is difficult to increase. From the above viewpoint, the amount of the metal oxide with respect to 100 parts by mass of the thermoplastic resin is preferably 0.5 parts by mass or more and 7.0 parts by mass or less, and 0.5 parts by mass or more and 3.0 parts by mass or less. It is more preferable that the amount is not more than parts.

  The content of the thermoplastic resin and the metal oxide is separated from the thermoplastic resin and the metal oxide by, for example, dissolving the thermoplastic resin in a solvent that dissolves only the thermoplastic resin contained in the powder material. Above, the content of the separated thermoplastic resin and metal oxide can be measured and determined.

  The child particles are fixed to the surface of the mother particles. In this specification, the term “adhering to the surface” means that a part of the surface of the child particle is in contact with the surface or the inside of the mother particle, and the other part of the surface of the child particle is not in contact with the mother particle. Means that it is exposed to the outside. FIG. 1 shows a state in which the child particles 12 are fixed to the mother particles 11 by partially embedding the child particles 12 in the mother particles 11.

  The fixed state can be determined by observing the composite particles with a known means such as a transmission electron microscope (TEM).

  The child particles are fixed to the mother particles with such a strength that the residual rate of the metal oxide after the powder material is ultrasonically dispersed in water is 20% by mass or more. Specifically, the child particles have a strength at which the residual ratio becomes 20% by mass or more when 3 g of the powder material is subjected to dispersion treatment with ultrasonic waves of 19.5 kHz ± 1 hKz in water at room temperature for 3 minutes. Thus, it is fixed to the mother particles. The water may contain a trace amount of a dispersant. In the present specification, the residual rate can be a value measured by the following method, for example.

(Example of ultrasonic dispersion processing method)
A 0.2% by mass aqueous solution of polyoxyethylene phenyl ether is prepared. 3 g of the powder material and 40 g of the aqueous solution are put into a 100 ml plastic cup to wet the powder material into the aqueous solution. Thereafter, an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-1200) chip is inserted into the aqueous solution, and the ammeter indicating the vibration indication value attached to the main unit shows 60 μA (50 W). The ultrasonic energy adjusted to is applied for 3 minutes. After the application of ultrasonic waves, the powder material filtered from the aqueous solution using a filter having an opening of 1 μm is washed with 60 ml of pure water and then dried.
When the powder material is sufficiently dried, the powder material is pressurized and pelletized, and a Kα analytical line obtained by measurement using a wavelength dispersion type X-ray fluorescence analyzer (manufactured by Shimadzu Corporation, LAB CENTER XRF-1700) Of these, the Net intensity of the peak derived from the metal oxide is determined. The strength obtained in the above procedure is divided by the strength obtained in the same manner from a powder material not subjected to ultrasonic treatment to obtain the residual ratio (%) of the metal oxide.

  If the residual ratio is 20% by mass or more, the composite particles can be filled more densely, and the accuracy of the three-dimensional structure can be sufficiently increased. From the viewpoint of suppressing the charging of the composite particles derived from the released fine particles and packing the particles more densely and making it difficult to reduce the accuracy of the three-dimensional structure, the residual rate may be 30% by mass or more. Preferably, it is 40% by mass or more, and more preferably 70% by mass or more. The residual rate can be adjusted by changing the strength of mixing and mixing by a machine when producing the powder material.

1-2. Other materials 1-2-1. Laser absorber From the viewpoint of more efficiently converting laser light energy into thermal energy, the powder material may further include a laser absorber. The laser absorber may be a material that absorbs a laser having a wavelength to be used and generates heat. Examples of such laser absorbers include carbon powder, nylon resin powder, pigments and dyes. These laser absorbers may be used alone or in combination of two types.

  The amount of the laser absorber can be appropriately set within a range in which the composite particles can be easily melted and bonded. For example, the amount of the laser absorber may be more than 0 mass% and less than 3 mass% with respect to the total mass of the powder material. it can.

1-2-2. Flow Agent From the viewpoint of further improving the fluidity of the powder material and facilitating the handling of the powder material during the production of the three-dimensional structure, the powder material may further include a flow agent. The flow agent may be a material having a small coefficient of friction and self-lubricating properties. Examples of such flow agents include silicon dioxide and boron nitride. These flow agents may be used alone or in combination. Even if the fluidity of the powder material is increased by the flow agent, the composite particles are not easily charged, and the composite particles can be filled more densely when forming a thin film.

  The amount of the flow agent can be appropriately set within a range in which the fluidity of the powder material is further improved and the composite particles are sufficiently melt-bonded. For example, 0% by mass with respect to the total mass of the powder material It can be more than 2% by mass.

2. The manufacturing method of a powder material This embodiment concerns on the manufacturing method of the said powder material. As shown in the flowchart of FIG. 2, the manufacturing method according to the present embodiment includes a step of producing particles containing a thermoplastic resin having an average particle diameter of 1 μm or more and 100 μm or less (step S201), and a volume larger than that of the thermoplastic resin. The step of preparing fine particles containing a metal oxide having a low resistivity (step S202), and the amount of the metal oxide with respect to 100 parts by mass of the thermoplastic resin is 0.5 parts by mass or more and 10 parts by mass or less. The process of fractionating by mass ratio and putting in a mixing apparatus (process S203), and the process of mixing and stirring these by a mixing apparatus (process S204) are included.

2-1. Step of producing particles containing thermoplastic resin (step S201)
The said thermoplastic resin should just be what can provide a desired characteristic to the three-dimensional molded item which it is going to manufacture from a powder material. Examples of the thermoplastic resin include thermoplastic resins that can be included in the above-mentioned powder material base particles.

  The particles containing the thermoplastic resin having the average particle diameter may be produced by a known method including a mechanical pulverization method and a wet method, or commercially available ones may be used.

  In the mechanical pulverization method, for example, a thermoplastic resin is mechanically pulverized to produce particles having a target average particle diameter. According to the mechanical grinding method, for example, particles containing a thermoplastic resin can be produced by the following method.

  The thermoplastic resin may be frozen and then pulverized, or may be pulverized at room temperature. The mechanical pulverization method can be performed by a known apparatus for pulverizing a thermoplastic resin. Examples of such devices include hammer mills, jet mills, ball mills, impeller mills, cutter mills, pin mills, and biaxial crushers. In the mechanical pulverization method, the thermoplastic resin may be fused by frictional heat generated from the thermoplastic resin during pulverization, and particles having a desired particle size may not be obtained. Therefore, it is preferable that the thermoplastic resin is cooled and brittle using liquid nitrogen or the like and then crushed.

  According to the mechanical pulverization method, the average particle diameter of the particles to be produced can be adjusted to a desired range by appropriately adjusting the amount of the solvent for the thermoplastic resin or the pulverization method or speed.

  In the wet method, for example, a dispersion liquid in which a thermoplastic resin is dispersed with a surfactant or the like is dried to obtain particles having a target average particle diameter. According to the wet method, for example, particles containing a thermoplastic resin can be produced by the following method.

(Example of method for producing particles containing thermoplastic resin by wet method)
10 parts by mass of a thermoplastic resin is dissolved in 100 parts by mass of an organic solvent to obtain a resin solution. In a liquid obtained by dissolving 100 parts by mass of a nonionic surfactant (for example, Emanon C-25 manufactured by Kao Corporation (“Emanon” is a registered trademark of the company)) in 2000 parts by mass of water, the above resin is used. The solution is added and sonication is performed for 10 minutes to obtain a resin dispersion. The resin dispersion is put into an evaporator and the pressure is reduced to remove the organic solvent, followed by filtration under reduced pressure to obtain a resin powder.

  According to the wet method, the average particle diameter of the produced particles can be adjusted to a desired range by appropriately adjusting the amount ratio of the resin, the surfactant and the dispersion.

  For the reasons described above, the average particle diameter of the mother particles is more preferably 5 μm or more and 70 μm or less, and further preferably 20 μm or more and 60 μm or less.

2-2. Step of preparing fine particles containing metal oxide (step S202)
The fine particles containing the metal oxide may be produced by a known method including an atomizing method, or a commercially available one may be used.

  The metal oxide only needs to have a volume resistivity lower than that of the thermoplastic resin. Examples of the metal oxide include a metal oxide that can be contained in the child particles of the powder material described above.

  The volume resistivity of the metal oxide is preferably 1/10 or less and more preferably 1/100 or less of the volume resistivity of the thermoplastic resin.

  The average particle diameter of the fine particles containing the metal oxide can be, for example, 10 nm or more and 500 nm or less. For the reason described above with respect to the child particles, the average particle size of the fine particles containing a metal oxide is preferably 10 nm or more and 100 nm or less, and more preferably 10 nm or more and 55 nm or less.

2-3. Mixing and stirring (steps S203 and S204)
The particles containing the thermoplastic resin and the fine particles containing the metal oxide are mixed at a mass ratio such that the amount of the metal oxide with respect to 100 parts by mass of the thermoplastic resin is 0.5 parts by mass or more and 10 parts by mass or less. It is put inside and mixed and stirred.

  In this embodiment, by mixing and stirring the particles containing the thermoplastic resin and the fine particles containing the metal oxide with a mixing device, the particles containing the thermoplastic resin and the fine particles containing the metal oxide are mixed with the residual rate. Can be fixed so as to be 20% by mass or more. By mechanically mixing and stirring with an apparatus, it becomes possible to embed fine particles containing a metal oxide in the surface of particles containing a thermoplastic resin with a strong physical force. This is probably because the adhesion rate of the fine particles containing the metal oxide has increased. On the other hand, as described in Patent Document 1, it is difficult to make the residual ratio 20% by mass or more simply by shaking a bag containing both.

  Examples of the mixing device include a Henschel mixer, a Nauter mixer, a Turbuler mixer, a hybridizer, and the like. These mixing apparatuses can be arbitrarily selected according to the requirements for producing the powder material. For example, when producing a larger amount of powder material at once, a Henschel mixer, a Nauter mixer, a turbuler mixer, etc. are preferable, and when it is desired to increase the residual rate at the same time, a mixing apparatus having stirring blades such as a Henschel mixer is preferable. . When using the mixing device having the stirring blade, it is possible to easily produce the powder material having the residual ratio by increasing the mixing time or increasing the peripheral speed of the stirring blade. Moreover, when it is desired to further increase the residual rate or to produce a powder material in a shorter time, a mixing apparatus capable of mixing with a stronger force such as a hybridizer is preferable.

  The strength and time of mixing and stirring for obtaining a powder material having a residual ratio of 20% by mass or more vary depending on the material used, the type of mixing device, etc., but according to the knowledge of the present inventors, a mixing device is used. Both can be fixed with sufficient strength by the usual setting for mixing and stirring. For example, in the case of a Henschel mixer, the stirring intensity is preferably 25 m / s or more and 55 m / s or less, and more preferably 30 m / s or more and 45 m / s or less. In addition, for example, in the case of a hybridizer, the stirring intensity is preferably 8000 rpm to 16300 rpm, more preferably 12000 rpm to 16300 rpm. The intensity and time of the mixing and stirring can be set to, for example, a peripheral speed of 40 m / s and 20 minutes, respectively, in the case of a Henschel mixer, and can be set to 16000 rpm and 5 minutes, respectively, in the case of a hybridizer.

  When the powder material contains a material other than particles containing a thermoplastic resin or fine particles containing a metal oxide, the particles containing the thermoplastic resin and the fine particles containing a metal oxide and the other materials are stirred and They may be mixed, or may be stirred and mixed in a plurality of times depending on the types of the other materials.

3. The manufacturing method of a three-dimensional molded item This embodiment concerns on the manufacturing method of the three-dimensional molded item using the said powder material. The method according to the present embodiment can be performed in the same manner as the ordinary powder bed fusion bonding method, except that the powder material is used. Specifically, the method according to the present embodiment includes (1) a step of forming a thin layer of the powder material, and (2) selectively irradiating the preheated thin layer with laser light, thereby A step of forming a shaped article layer formed by fusion bonding of composite particles contained in the material, and a step of (3) repeating the step (1) and the step (2) a plurality of times in this order, and laminating the shaped article layer, and including. By the step (2), one of the three-dimensional objects constituting the three-dimensional object is formed, and the next layer of the three-dimensional object is further performed by repeating the steps (1) and (2) in the step (3). It is laminated and the final three-dimensional model is manufactured. The manufacturing method according to this embodiment may further include (4) a step of preheating the thin layer of the formed powder material at least before step (2).

3-1. Step of forming a thin layer made of a powder material (step (1))
In this step, a thin layer of the powder material is formed. For example, the powder material supplied from the powder supply unit is laid flat on a modeling stage by a recoater. The thin layer may be formed directly on the modeling stage, or may be formed so as to be in contact with the already spread powder material or the already formed modeling layer.

  The thickness of the thin layer can be set according to the thickness of the shaped article layer. Although the thickness of a thin layer can be arbitrarily set according to the precision of the three-dimensional molded item to manufacture, it is 0.01 mm or more and 0.30 mm or less normally. By setting the thickness of the thin layer to 0.01 mm or more, the composite particles of the lower layer are melt-bonded or the modeling layer of the lower layer is re-melted by laser irradiation for forming the next layer. Can be prevented. By making the thickness of the thin layer 0.30 mm or less, the laser energy is conducted to the lower part of the thin layer, and the composite particles contained in the powder material constituting the thin layer are sufficiently melted throughout the thickness direction. Can be combined. From the above viewpoint, the thickness of the thin layer is more preferably 0.01 mm or more and 0.10 mm or less. In addition, from the viewpoint of more fully melting and bonding the composite particles throughout the thickness direction of the thin layer and making cracks between the layers less likely to occur, the thickness of the thin layer is different from the laser beam spot diameter described later. Is preferably set to be within 0.10 mm.

3-2. A step of forming a shaped article layer formed by fusion bonding of composite particles (step (2))
In this step, a laser is selectively irradiated to the position where the shaped article layer is to be formed in the formed thin layer, and the composite particles at the irradiated position are melt-bonded. Thereby, adjacent composite particles are melted together to form a melt-bonded body, thereby forming a shaped article layer. At this time, the composite particles that have received the energy of the laser are also melt-bonded to the already formed layer, so that adhesion between adjacent layers also occurs.

What is necessary is just to set the wavelength of a laser within the range which the said thermoplastic resin absorbs. At this time, it is preferable to reduce the difference between the wavelength of the laser and the wavelength at which the absorption rate of the thermoplastic resin is highest. However, since the resin can absorb light in various wavelength regions, the CO ₂ laser It is preferable to use a laser having a wide wavelength band. For example, the wavelength of the laser is preferably 0.8 μm or more and 12 μm or less.

  For example, the power at the time of laser output may be set within a range where the thermoplastic resin is sufficiently melt-bonded at the laser scanning speed described later, and specifically, it is set to 5.0 W or more and 60 W or less. Can do. From the viewpoint of lowering the laser energy, lowering the manufacturing cost, and simplifying the configuration of the manufacturing apparatus, the power at the time of laser output is preferably 30 W or less, and 20 W or less. Is more preferable.

  The laser scanning speed may be set within a range that does not increase the manufacturing cost and does not excessively complicate the apparatus configuration. Specifically, it is preferably 1 mm / second to 100 mm / second, more preferably 1 mm / second to 80 mm / second, further preferably 2 mm / second to 80 mm / second, and more preferably 3 mm. / Mm or more and 80 mm / second or less is more preferable, and 3 mm / second or more and 50 mm / second or less is further preferable.

  The beam diameter of the laser can be appropriately set according to the accuracy of the three-dimensional structure to be manufactured.

3-3. The process of laminating a model object layer (process (3))
In this step, the step (1) and the step (2) are repeated to laminate the shaped article layer formed by the step (2). A desired three-dimensional modeled object is manufactured by laminating the modeled object layers.

3-4. A step of preheating the thin layer of the formed powder material (step (4))
In this step, the thin layer of the powder material is preheated prior to step (2). For example, the surface of the thin layer can be heated to 15 ° C. or lower, preferably 5 ° C. or lower, from the melting point of the thermoplastic resin by a heater or the like.

3-5. Other From the viewpoint of preventing the strength of the three-dimensional structure from being lowered due to oxidation of the composite particles during fusion bonding, at least step (2) is preferably performed under reduced pressure or in an inert gas atmosphere. The pressure when reducing the pressure is preferably 10 ⁻² Pa or less, and more preferably 10 ⁻³ Pa or less. Examples of the inert gas that can be used in the present embodiment include nitrogen gas and rare gas. Among these inert gases, nitrogen (N ₂ ) gas, helium (He) gas, or argon (Ar) gas is preferable from the viewpoint of availability. From the viewpoint of simplifying the production process, all of the steps (1) to (3) (when including the step (4), all of the steps (1) to (4)) are performed under reduced pressure or an inert gas. It is preferable to carry out in an atmosphere.

4). Three-dimensional modeling apparatus This embodiment concerns on the apparatus which manufactures a three-dimensional molded item using the said powder material. The apparatus which concerns on this embodiment can be set as the structure similar to the well-known apparatus which manufactures the three-dimensional molded item by the powder bed melt-bonding method except using the said powder material. Specifically, as shown in FIG. 3 which is a side view schematically showing the configuration of the three-dimensional modeling apparatus 300 according to the present embodiment, the modeling stage 310 located in the opening, the powder material including the composite particles A thin film forming section 320 for forming a thin film on the modeling stage, a laser irradiation section 330 for irradiating the thin film with a laser to form a model layer formed by fusion bonding of the composite particles, and a variable position in the vertical direction Are provided with a stage support part 340 for supporting the modeling stage 310 and a base 345 for supporting the above-mentioned parts.

  As shown in FIG. 4 showing the main part of the control system, the three-dimensional modeling apparatus 300 controls the thin film forming unit 320, the laser irradiation unit 330, and the stage support unit 340 to repeatedly form the modeled object layer. A control unit 350 to be stacked, a display unit 360 for displaying various types of information, an operation unit 370 including a pointing device for receiving instructions from a user, and various types of information including a control program executed by the control unit 350 are stored. You may provide the data input part 390 containing the interface etc. for transmitting / receiving various information, such as 3D modeling data, with the memory | storage part 380 and an external device. The three-dimensional modeling apparatus 300 may be connected to a computer device 400 for generating data for three-dimensional modeling.

  On the modeling stage 310, a modeling material layer is formed by forming a thin layer by the thin film forming unit 320 and irradiating the laser by the laser irradiation unit 330, and the modeling material layer is laminated to form a three-dimensional modeled object. .

  The thin film forming unit 320 includes, for example, an edge of an opening on which the modeling stage 310 moves up and down, an opening having the edge on the substantially same plane in the horizontal direction, a powder material storage unit extending vertically downward from the opening, and A powder supply unit 321 provided at the bottom of the powder material storage unit and provided with a supply piston that moves up and down in the opening, and a recoater 322a that lays the supplied powder material flat on the modeling stage 310 to form a thin layer of powder material It can be set as the structure provided with.

  The powder supply unit 321 includes a powder material storage unit and a nozzle provided vertically above the modeling stage 310, and discharges the powder material on the same plane as the modeling stage. It is good also as a structure.

The laser irradiation unit 330 includes a laser light source 331 and a galvanometer mirror 332a. The laser irradiation unit 330 may include a lens (not shown) for adjusting the focal length of the laser to the surface of the thin layer. The laser light source 331 may be a light source that emits the laser having the wavelength with the output. Examples of the laser light source 331 include a YAG laser light source, a fiber laser light source, and a CO ₂ laser light source. The galvano mirror 332a may include an X mirror that reflects the laser emitted from the laser light source 331 and scans the laser in the X direction and a Y mirror that scans in the Y direction.

  The stage support unit 340 supports the modeling stage 310 variably in the position in the vertical direction. That is, the modeling stage 310 is configured to be precisely movable in the vertical direction by the stage support 340. Various configurations can be adopted as the stage support unit 340. For example, the stage support unit 340 is related to a holding member that holds the modeling stage 310, a guide member that guides the holding member in the vertical direction, and a screw hole provided in the guide member. It can be constituted by a ball screw or the like to be combined.

  The controller 350 controls the overall operation of the 3D modeling apparatus 300 during the modeling operation of the 3D model.

  In addition, the control unit 350 includes a hardware processor such as a central processing unit. For example, a plurality of slices obtained by thinly cutting the 3D modeling data acquired from the computer device 400 by the data input unit 390 in the stacking direction of the modeling material layers It may be configured to convert to data. Slice data is modeling data of each modeling material layer for modeling a three-dimensional modeled object. The thickness of the slice data, that is, the thickness of the modeling material layer coincides with the distance (lamination pitch) corresponding to the thickness of one layer of the modeling material layer.

  Display unit 360 can be, for example, a liquid crystal display or a monitor.

  The operation unit 370 may include a pointing device such as a keyboard and a mouse, and may include various operation keys such as a numeric keypad, an execution key, and a start key.

  The storage unit 380 can include various storage media such as a ROM, a RAM, a magnetic disk, an HDD, and an SSD.

  The three-dimensional modeling apparatus 300 receives the control of the control unit 350 and depressurizes the inside of the apparatus. The decompression unit (not shown) such as a decompression pump or the control unit 350 controls the inert gas into the apparatus. You may provide the inert gas supply part (not shown) to supply. The three-dimensional modeling apparatus 300 may include a heater (not shown) that heats the inside of the apparatus, in particular, the upper surface of a thin layer made of a powder material, under the control of the control unit 350.

4-1. Example of 3D modeling using 3D modeling apparatus 300 The control unit 350 converts the 3D modeling data acquired from the computer apparatus 400 by the data input unit 390 into a plurality of slice data sliced in the stacking direction of the modeling material layer. Thereafter, the control unit 350 controls the following operations in the three-dimensional modeling apparatus 300.

  The powder supply unit 321 drives a motor and a drive mechanism (both not shown) according to the supply information output from the control unit 350, moves the supply piston upward in the vertical direction (arrow direction in the drawing), and the modeling stage And extrude the powder material on the same horizontal plane.

  Thereafter, the recoater driving unit 322 moves the recoater 322a in the horizontal direction (arrow direction in the figure) according to the thin film formation information output from the control unit 350, conveys the powder material to the modeling stage 310, and the thin layer The powder material is pressed so that the thickness becomes the thickness of one layer of the shaped article layer.

  Thereafter, the laser irradiation unit 330 emits a laser beam from the laser light source 331 in accordance with the laser irradiation information output from the control unit 350, conforming to the region constituting the three-dimensional structure in each slice data on the thin film, and the galvano The mirror driving unit 332 drives the galvanometer mirror 332a to scan the laser. The composite particles contained in the powder material are melt-bonded by laser irradiation, and a shaped article layer is formed.

  Thereafter, the stage support unit 340 drives a motor and a drive mechanism (both not shown) according to the position control information output from the control unit 350, and moves the modeling stage 310 vertically downward (arrow direction in the figure) by the stacking pitch. )

  The display unit 360 displays various information and messages that should be recognized by the user under the control of the control unit 350 as necessary. The operation unit 370 receives various input operations by the user and outputs an operation signal corresponding to the input operation to the control unit 350. For example, a virtual three-dimensional model to be formed is displayed on the display unit 360 to check whether or not a desired shape is formed. If the desired shape is not formed, the operation unit 370 may be modified. Good.

  The control unit 350 stores data in the storage unit 380 or extracts data from the storage unit 380 as necessary.

  By repeating these operations, the modeled object layer is laminated and a three-dimensional modeled object is manufactured.

  In the following, specific examples of the present invention will be described. These examples do not limit the scope of the present invention.

1. 1. Production of powder material 1-1. Production of Particles Containing Thermoplastic Resin Particles containing a thermoplastic resin were produced by the following procedure.

Caliber 301-4 manufactured by Sumika Stylon Polycarbonate Co., Ltd. was processed to a mean particle size of 50 μm by a mechanical pulverization method to obtain particles containing polycarbonate (hereinafter also simply referred to as “polycarbonate”). The volume resistivity of the polycarbonate was larger than 1 × 10 ¹⁵ Ω · cm and not more than 1 × 10 ¹⁶ Ω · cm.

UBE polyethylene F022NH manufactured by Ube Maruzen Polyethylene Co., Ltd. (“UBE polyethylene” is a registered trademark of the company) is processed to a mean particle size of 50 μm by a mechanical pulverization method, and particles containing polyethylene (hereinafter simply referred to as “polyethylene”) Got. The volume resistivity of the polyethylene was more than 1 × 10 ¹⁶ Ω · cm and not more than 1 × 10 ¹⁹ Ω · cm.

Alamin CM1001 manufactured by Toray Industries, Inc. was processed by mechanical pulverization to an average particle size of 50 μm to obtain particles containing nylon 6 (hereinafter also simply referred to as “nylon 6”). The volume resistivity of the nylon 6 was greater than 1 × 10 ¹³ Ω · cm and 1 × 10 ¹⁴ Ω · cm or less.

UBESTA3014U (“UBESTA” is a registered trademark of Ube Industries) manufactured by Ube Industries, Ltd. was processed to a mean particle size of 50 μm by a mechanical pulverization method to obtain particles containing nylon 12 (hereinafter also simply referred to as “nylon 12”). . The volume resistivity of the nylon 12 was greater than 1 × 10 ¹³ Ω · cm and 1 × 10 ¹⁴ Ω · cm or less.

  In addition, the average particle diameter and volume resistivity of each material referred to values published by each manufacturer. When there was no published value, it was measured by the following method. Further, in any of the above particles, the content of components other than the thermoplastic resin described above was negligible.

(Measurement of average particle size)
The particle diameter of 100 particles arbitrarily selected from the microscopic image of the powdery material imaged with a transmission electron microscope (TEM) was measured, and the average value was taken as the average particle diameter of the particles.

(Measurement of volume resistivity)
The powdery material was molded into a 9 cm × 9 cm × 5 cm cylindrical shape by applying a pressure of 3 t. The volume resistivity of this cylindrical material was measured with a Hirester UX MCP-HT800 manufactured by Mitsubishi Chemical Analytech.

1-2. Preparation of fine particles containing metal oxide The following materials were prepared as fine particles containing metal oxide.

T805, manufactured by Nippon Aerosil Co., Ltd., was prepared as fine particles containing titanium oxide (hereinafter also simply referred to as “titanium oxide”). The average particle diameter of the fine particles was 20 nm, and the volume resistivity was about 1 × 10 ¹² Ω · cm.

380 manufactured by Nippon Aerosil Co., Ltd. was prepared as fine particles containing silica (hereinafter also simply referred to as “silica 1”). The average particle diameter of the fine particles was 20 nm, and the volume resistivity was about 1 × 10 ¹⁰ Ω · cm.

As fine particles containing alumina (hereinafter, also simply referred to as “alumina”), fine particles having an average particle diameter of 30 nm prepared by pulverizing A-484 by Kyocera Corporation with a ball mill were prepared. The volume resistivity of the fine particles was larger than 1 × 10 ¹⁴ Ω · cm and not more than 1 × 10 ¹⁵ Ω · cm.

R805 manufactured by Nippon Aerosil Co., Ltd. was prepared as fine particles containing silica (hereinafter also simply referred to as “silica 2”). The average particle diameter of the fine particles was 10 nm, and the volume resistivity was about 1 × 10 ¹⁵ Ω · cm.

  In addition, the average particle diameter and volume resistivity of each material referred to values published by each manufacturer. When there was no published value, it measured by the method similar to the said thermoplastic resin. Further, in any of the above particles, the content of components other than the above metal oxide was negligible.

1-3. Mixing and stirring 1-3-1. Powder material 1
100 parts by mass of the polycarbonate-containing particles and 0.5 parts by mass of the titanium oxide-containing particles are put into a Henschel mixer (manufactured by Nihon Coke Kogyo Co., Ltd., FM20C / I type). The number of rotations was set to 40 m / s, and the mixture was stirred for 20 minutes. The product temperature at the time of mixing is set to 40 ° C. ± 1 ° C. When the temperature reaches 41 ° C., cooling water is flowed to the outer bath of the Henschel mixer at a flow rate of 5 L / min. The temperature inside the Henschel mixer was controlled by flowing cooling water at 1 L / min. The powder thus obtained was designated as powder material 1.

1-3-2. Powder material 2
Powder material 2 was obtained in the same manner except that the amount of titanium oxide input was changed to 5.0 parts by mass in the production of powder material 1.

1-3-3. Powder material 3
Powder material 3 was obtained in the same manner except that the amount of titanium oxide input was changed to 10.0 parts by mass in the production of powder material 1.

1-3-4. Powder material 4
100 parts by mass of the above polycarbonate and 0.5 parts by mass of the above titanium oxide were put into a hybridizer (manufactured by Nara Machinery Co., Ltd., NHS-0 type), set at a rotational speed of 16000 rpm and stirred for 5 minutes. . The product temperature at the time of mixing is set to 75 ° C. ± 1 ° C. When 76 ° C., cooling water is flowed to the outer bath of the hybridizer at a flow rate of 5 L / min. The temperature inside the hybridization system was controlled by flowing cooling water at 1 L / min. The powder thus obtained was designated as powder material 4.

1-3-5. Powder material 5
Powder material 5 was obtained in the same manner except that the amount of titanium oxide input was changed to 5.0 parts by mass in preparation of powder material 4.

1-3-6. Powder material 6
Powder material 6 was obtained in the same manner except that the amount of titanium oxide input was changed to 10.0 parts by mass in the preparation of powder material 4.

1-3-7. Powder material 7
Powder material 7 was obtained in the same manner except that titanium oxide was changed to 2.0 parts by mass of silica 1 in preparation of powder material 1.

1-3-8. Powder material 8
Powder material 7 was obtained in the same manner except that titanium oxide was changed to 1.0 part by mass of alumina in preparation of powder material 1.

1-3-9. Powder material 9-16
In the production of the powder materials 1 to 8, powder materials 9 to 16 were obtained in the same manner except that the polycarbonate was changed to 100 parts by mass of the polyethylene.

1-3-10. Powder material 17-23
In the production of powder materials 1 to 7, powder materials 17 to 23 were obtained in the same manner except that the polycarbonate was changed to 100 parts by mass of nylon 6 described above.

1-3-11. Powder material 24
100 parts by mass of the nylon 12 was taken into a polyethylene bag, and 5.0 parts by mass of the silica 2 was added thereto and shaken by hand for about 3 minutes without using a machine. The powder thus obtained was designated as powder material 24.

1-3-12. Powder material 25
In the production of the powder material 1, a powder material 25 was obtained in the same manner except that the polycarbonate was changed to 100 parts by mass of the nylon 12 and the titanium oxide was changed to 5.0 parts by mass of the silica 2.

1-3-13. Powder material 26
A powder material 26 was obtained in the same manner except that the amount of titanium oxide input was changed to 0.1 parts by mass in preparation of the powder material 1.

1-3-14. Powder material 27
Powder material 27 was obtained in the same manner except that the amount of titanium oxide input was changed to 20.0 parts by mass in preparation of powder material 1.

1-3-15. Powder material 28
100 parts by mass of the polycarbonate was dispensed into a polyethylene bag, and 5.0 parts by mass of the titanium oxide was added thereto and shaken by hand for about 3 minutes without using a machine. The powder thus obtained was designated as powder material 28.

  The kind of thermoplastic resin contained in the particles containing the thermoplastic resin used for the production of the powder materials 1 to 28, the volume resistivity of the thermoplastic resin and the amount of the particles containing the thermoplastic resin, the fine particles containing the metal oxide Tables 1 and 2 show the types of metal oxides contained, the volume resistivity of metal oxides, the amount of fine particles containing metal oxides, and the mixing and stirring methods.

2. Evaluation 2-1. Residual rate 3 g of powder material 1 and 40 g of 0.2% by mass aqueous solution of polyoxyethylene phenyl ether were put into a 100 ml plastic cup to wet powder material 1 in the aqueous solution. Thereafter, an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-1200) chip is inserted into the aqueous solution, and the ammeter indicating the vibration indication value attached to the main unit shows 60 μA (50 W). Was applied for 3 minutes (wavelength: 19.5 kHz ± 1 hKz). After application of the ultrasonic wave, the powder material 1 filtered from the aqueous solution using a filter having an opening of 1 μm was washed with 60 ml of pure water and then dried.

  After the powder material 1 is sufficiently dried, the powder material 1 is pressed and pelletized, and a Kα analysis line obtained using a wavelength dispersive X-ray fluorescence analyzer (manufactured by Shimadzu Corporation, LAB CENTER XRF-1700). Among them, the peak Net intensity derived from titanium oxide was determined. The strength obtained by the above procedure was divided by the strength obtained in the same manner from the powder sample 1 not subjected to ultrasonic treatment, and the residual ratio (%) of titanium oxide was obtained.

  For the powder samples 2 to 28, the residual ratio (%) of titanium oxide, silica 1, alumina, or silica 2 after ultrasonic treatment was similarly determined.

2-2. Defects of Modeled Objects Powder materials 1 to 28 were spread on a modeling stage of a three-dimensional modeling apparatus using a powder bed fusion bonding method having the basic configuration shown in FIG. 3 to form a thin layer having a thickness of 0.1 mm. This thin layer was irradiated with a laser in a range of 15 mm in length and 20 mm in width from a 50 W fiber laser (manufactured by SPI Lasers) equipped with a YAG wavelength galvanometer scanner under the following conditions to produce a single-layer structure. .

[Laser emission conditions]
Laser output: 20W
Laser wavelength: 1.07 μm
Beam diameter: 170 μm on the surface of the thin layer

[Laser scanning conditions]
Scanning speed: 3.0 mm / sec
Scanning interval: 0.2 mm

[Ambient atmosphere]
Temperature: Normal temperature Gas: Argon (Ar) 100%

  Each shaped product produced from each of the powder materials 1 to 28 is visually observed, and the shaped product has a defect larger than the size of the composite particles (about 0.1 mm) (the portion where the shaped product is not formed and becomes a void). I confirmed. When there is no defect, the defect of the model is evaluated as “◎”, and when the number of defects is 1 or more and 10 or less, the defect of the model is evaluated as “◯”, and the number of defects Was 11 or more and 29 or less, the defect of the shaped object was evaluated as “Δ”, and when the number of defects was 30 or more, the defect of the formed object was evaluated as “x”.

  Table 3 shows the evaluation results of the residual ratio and the defect of the shaped product with respect to the powder materials 1 to 28.

  A composite particle comprising: a mother particle containing a thermoplastic resin; and a child particle containing a metal oxide having a volume resistivity lower than that of the thermoplastic resin, which is fixed to the surface of the mother particle. The residual ratio of the metal oxide after the ultrasonic dispersion treatment of the powder material in water is 20% by mass with respect to the thermoplastic resin having a content of 100 parts by mass. By using the powder materials 1 to 23 as described above, it was possible to produce a three-dimensional model with few defects. The main factor for this is considered to be that a thin layer in which the powder material is closely packed can be formed while suppressing the charging of the composite particles.

  In addition, the powder materials 1, 4, 9, 12, 17 and 20 in which the amount of the metal oxide with respect to 100 parts by mass of the thermoplastic resin is 0.5 parts by mass or more and 3.0 parts by mass or less are metal oxides Compared with powder materials 2, 3, 10, 11, 18, and 19 of the same type but different amounts, the residual rate of the metal oxide after ultrasonic dispersion treatment of the powder material in water is higher, resulting in more defects. It was possible to produce a three-dimensional model with a small amount.

  Moreover, the powder materials 4-6, 12-14, 20-22 produced using the hybridizer are the powder materials 2, 3, 10, 11, 18, 19 produced using the Henschel mixer with the same combination of materials. In addition, the residual rate of the metal oxide after the powder material was subjected to ultrasonic dispersion treatment in water was higher, and a three-dimensional structure with fewer defects could be produced.

  On the other hand, in the powder materials 24 and 28 produced by shaking without using a mixer, the residual ratio did not exceed 20% by mass. Moreover, when the three-dimensional modeling was performed using the powder materials 24 and 28 having the residual rate of less than 20% by mass, the modeled object was easily damaged. This is because, in powder materials produced without using a machine, fine particles containing metal oxides that could not be fixed to the mother particles are free and exist, so that the composite particles are easily charged by friction and form a thin layer. This is probably because the composite particles were not filled with sufficient density due to electrical repulsion between the particles.

  Moreover, when three-dimensional modeling was performed using the powder material 25 containing fine particles containing a metal oxide having a volume resistivity higher than that of the thermoplastic resin, it was easy to cause defects in the modeled product. This is because the particles are charged due to friction between the particles and the modeling stage, and the charge is not easily released from the particles, so that the composite particles are easily charged. This is probably because the composite particles were not filled with sufficient density due to electrical repulsion.

  Moreover, when three-dimensional modeling was performed using the powder material 26 having a metal oxide content of less than 0.5 parts by mass with respect to 100 parts by mass of the thermoplastic resin, defects were likely to occur in the modeled object. This is thought to be because the composite particles were not filled at a sufficient density due to the electrical repulsion between the particles when forming a thin layer because the charges were not sufficiently released from the particles.

  Moreover, when three-dimensional modeling was performed using the powder material 27 having a metal oxide content of more than 10.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin, it was easy to cause defects in the modeled object. This is because the content of fine particles containing a metal oxide is large, and the fine particles containing a metal oxide that could not be fixed to the mother particles were free and existed. This is probably because the composite particles were not filled at a sufficient density due to electrical repulsion between the particles.

  According to the powder material according to the present invention, modeling with higher accuracy is possible by the powder bed fusion bonding method. Moreover, according to the manufacturing method of the powder material which concerns on this invention, the powder material which enables modeling with higher precision than the above can be manufactured. Therefore, the present invention can contribute to further spread of the powder bed fusion bonding method.

DESCRIPTION OF SYMBOLS 10 Powder material 11 Mother particle 12 Child particle 300 Three-dimensional modeling apparatus 310 Modeling stage 320 Thin film formation part 321 Powder supply part 322 Recoater drive part 322a Recoater 330 Laser irradiation part 331 Laser light source 332 Galvano mirror drive part 332a Galvano mirror 340 Stage support part 345 Base 350 Control unit 360 Display unit 370 Operation unit 380 Storage unit 390 Data input unit 400 Computer device

Claims (10)

Three-dimensional modeling by selectively irradiating a thin layer of a powder material containing composite particles with laser light to form a modeled product layer formed by sintering or melt bonding the composite particles, and laminating the modeled product layer A powder material used in the manufacture of goods,
The composite particle includes a mother particle containing a thermoplastic resin having an average particle diameter of 1 μm or more and 100 μm or less, and a child particle containing a metal oxide fixed to the surface of the mother particle and having a volume resistivity lower than that of the thermoplastic resin. And including
The powder material contains 0.5 parts by weight or more and 10 parts by weight or less of the metal oxide with respect to 100 parts by weight of the thermoplastic resin,
The powder material with respect to the powder material, wherein the residual rate of the metal oxide after the powder material is ultrasonically dispersed in water is 20% by mass or more.   The powder material according to claim 1, wherein an average particle size of the child particles is 10 nm or more and 500 nm or less.   The powder material according to claim 1 or 2, wherein a volume resistance value of the metal oxide is 1/10 or less of a volume resistance value of the thermoplastic resin.   The powder material according to claim 1 or 2, wherein a volume resistance value of the metal oxide is 1/100 or less of a volume resistance value of the thermoplastic resin.   The powder material according to any one of claims 1 to 4, wherein an average particle diameter of the mother particles is 5 µm or more and 70 µm or less.   The residual rate of the said metal oxide is a powder material as described in any one of Claims 1-5 which is 30 mass% or more. Three-dimensional modeling by selectively irradiating a thin layer of a powder material containing composite particles with laser light to form a modeled product layer formed by sintering or melt bonding the composite particles, and laminating the modeled product layer A method of manufacturing a powder material used for manufacturing a product,
The metal for 100 parts by mass of the thermoplastic resin using particles containing a thermoplastic resin having an average particle diameter of 1 μm or more and 100 μm or less and fine particles containing a metal oxide having a volume resistivity lower than that of the thermoplastic resin The manufacturing method including the process of mixing and stirring with a mixing apparatus by the mass ratio from which the quantity of an oxide will be 0.5 to 10 mass parts.   In the said mixing and stirring process, the manufacturing method of Claim 7 using the microparticles | fine-particles containing the said metal oxide whose average particle diameter is 10 nm or more and 500 nm or less. Forming a thin layer of the powder material according to any one of claims 1 to 6 or the powder material produced by the production method according to claim 7 or 8, and
A step of selectively irradiating the formed thin layer with laser light to form a shaped article layer formed by sintering or fusion bonding of composite particles contained in the powder material;
The step of forming the thin layer and the step of forming the shaped article layer are repeated a plurality of times in this order, and the step of laminating the shaped article layer,
The manufacturing method of the three-dimensional molded item containing. Modeling stage,
A thin film forming section for forming a thin film of the powder material according to any one of claims 1 to 6 or the powder material manufactured by the manufacturing method according to claim 7 or 8 on the modeling stage;
A laser irradiation unit for irradiating the thin film with a laser to form a shaped article layer formed by sintering or melting the particles;
A stage support section that variably supports the vertical position of the modeling stage;
A control unit that controls the thin film forming unit, the laser irradiation unit, and the stage support unit to repeatedly form and stack the shaped article layer;
A three-dimensional modeling apparatus.

Images