Three-dimensional object manufacturing method, three-dimensional object manufacturing device and three-dimensional object

Abstract

A method for manufacturing a three-dimensional object using primary particles containing at least a ceramic material is provided, the method comprising: a forming step of forming a layer using secondary particles containing primary particles and a binding resin; and an applying step of applying a liquid for dissolving the binding resin to the layer formed in the forming step, wherein the central particle diameter of the primary particles is 5 microns or less.

Description

Technical Field

[0001] The present disclosure relates to a three-dimensional object manufacturing method, a three-dimensional object manufacturing device, and a three-dimensional object. Background Art

[0002] Recently, resin powders such as those described in, for example, Japanese Patent No. 6520182 are known as resin powders for manufacturing complex, minute three-dimensional objects. However, even when objects are manufactured using the resin powders described in Japanese Patent No. 6520182, it is difficult to obtain a high-precision, high-density ceramic sintered body. Summary of the invention

[0003] According to one aspect of the present disclosure, a method for manufacturing a three-dimensional object using primary particles (primary particles) containing at least a ceramic material comprises: a forming (molding) step of forming a layer using secondary particles containing primary particles and a binding resin, and an applying step of applying a liquid for dissolving the binding resin to the layer formed in the forming step. The central particle diameter of the primary particles is 5 micrometers or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 is a conceptual diagram showing an example of a method for manufacturing a three-dimensional object;

[0005] Figure 2 is a flow chart showing an example of a process flow of a three-dimensional object manufacturing method;

[0006] Figure 3 is a functional block diagram illustrating an example of a three-dimensional object manufacturing apparatus;

[0007] Figure 4A is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 1);

[0008] Figure 4B is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 2);

[0009] Figure 4C is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 3);

[0010] Figure 4D is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 4);

[0011] Figure 4E is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 5); and

[0012] Figure 4F is a schematic diagram showing an example of a method for manufacturing a three-dimensional object (Part 6). DETAILED DESCRIPTION

[0013] (Three-dimensional object manufacturing method and three-dimensional object manufacturing device)

[0014] The three-dimensional object manufacturing method of the present disclosure is a method for manufacturing a three-dimensional object using primary particles containing at least a ceramic material, and includes: a forming step of forming a layer using secondary particles containing primary particles and a binding resin, and an applying step of applying a liquid for dissolving the binding resin to the layer formed in the forming step. The central particle diameter of the primary particles is 5 microns or less. The three-dimensional object manufacturing method further includes other steps as needed.

[0015] The three-dimensional object manufacturing device of the present disclosure is a device configured to manufacture a three-dimensional object using primary particles containing at least a ceramic material, and includes: a forming unit (means) configured to form a layer using secondary particles containing primary particles and a binding resin, and an applying unit configured to apply a liquid for dissolving the binding resin to the layer formed by the forming unit. The central particle size of the primary particles is 5 microns or less. The three-dimensional object manufacturing device further includes other units as needed.

[0016] The three-dimensional object manufacturing method of the present disclosure can be suitably performed by the three-dimensional object manufacturing device of the present disclosure. The forming step can be performed by a forming unit. The applying step can be performed by an applying unit. Other steps can be performed by other units.

[0017] An object of the present disclosure is to provide a method for manufacturing a three-dimensional object that can obtain a high-precision, high-density ceramic sintered body.

[0018] The present disclosure can provide a method for manufacturing a three-dimensional object capable of obtaining a high-precision, high-density ceramic sintered body.

[0019] The present disclosure uses a binding resin to granulate ceramic primary particles with a small particle size of nanometers into secondary particles, uses the secondary particles to form a powder layer, and applies a liquid for dissolving the binding resin to the surface of the powder layer to return (restore) the secondary particles to the primary particles and promote densification. In this way, the present disclosure can produce a high-density green body. Therefore, the present disclosure can suppress the occurrence of internal defects in the green body and obtain a sintered body with high strength, as well as suppress cracking and deformation in any heat treatment step (such as degreasing and sintering) and obtain a ceramic sintered body with high shape accuracy.

[0020] Furthermore, the present disclosure can obtain a high-density ceramic sintered body even having a thickness of several centimeters without having, for example, deformation and cracking of a molded body.

[0021] The following serve as definitions of terms used in this disclosure.

[0022] In the present disclosure, "three-dimensional object manufacturing" means the steps taken until a green body that has not yet undergone a debinding step is manufactured. In the present disclosure, a "green body" means an object formed of ceramic, a binding resin, and a solvent formed by repeatedly performing a forming step and an applying step. In the present disclosure, a "three-dimensional object" mainly means a component that has passed all the steps involved, that is, a component in a state obtained by debinding and sintering.

[0023] The three-dimensional object manufacturing method of the present disclosure includes a forming step and an applying step, and further includes other steps as needed. By repeating the forming step and the applying step a predetermined number of times, a uniform, high-precision green body can be obtained.

[0024] The three-dimensional object manufacturing apparatus of the present disclosure includes a forming unit and an applying unit, and further includes other units as needed.

[0025] <Formation Step and Formation Unit>

[0026] The forming step is a step of forming a layer using secondary particles containing primary particles and a binding resin, and is performed by a forming unit. The forming step is performed using secondary particles containing at least primary particles and a binding resin, and is a step of forming a powder layer and may be referred to as a "powder layer forming step".

[0027] -Primary particles-

[0028] The main component of the primary particles of the present disclosure is ceramics. Ceramics means a sintered body obtained by heating and sintering an inorganic material.

[0029] Regarding the ceramic as the main component, the ceramic is contained in the primary particles in an amount of more than 50% by mass. The ceramic content in the primary particles is preferably 80% by mass or more and more preferably 90% by mass or more.

[0030] Examples of raw materials of ceramics include glass, metal oxides, metal carbides, and metal nitrides.

[0031] Examples of glass include silica glass (quartz glass) and soda lime silica glass.

[0032] Examples of the metal oxide include zirconium oxide, aluminum oxide, and mullite (aluminosilicate mineral).

[0033] Examples of metal carbides include silicon carbide and tungsten carbide.

[0034] Examples of metal nitrides include silicon nitride and aluminum nitride.

[0035] One of these ceramics may be used alone, or two or more of these ceramics may be used in combination. Among these ceramics, zirconium oxide, aluminum oxide, mullite (aluminosilicate mineral), tungsten carbide, silicon carbide, silicon nitride, and aluminum nitride are preferred in terms of maintaining high strength.

[0036] The central particle diameter of the primary particles is 5 micrometers or less, preferably 1 micrometer or less, and even more preferably 500 nm or less. The lower limit of the central particle diameter of the primary particles is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 50 nm or more.

[0037] When the central particle diameter of the primary particles is 5 μm or less, a high-density green body having few internal defects can be produced.

[0038] The central particle diameter of the primary particles has the same meaning as the particle diameter based on the cumulative 50% of the volumetric particle size distribution, and can be measured with, for example, a laser diffraction / scattering particle size measuring instrument (available from Horiba, Ltd., LA-300).

[0039] The powder for manufacturing three-dimensional objects is manufactured by manufacturing secondary particles using primary particles. Because the primary particles have a small particle size, the primary particles have poor fluidity and poor operability. Therefore, the primary particles are processed into secondary particles to have good operability.

[0040] The method for producing the secondary particles is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the method include a method of mixing a binding resin with the primary particles by a known method.

[0041] The method for granulating the primary particles using the binding resin is not particularly limited and can be appropriately selected from known granulation methods. Examples of the method include a tumbling fluidized bed method, a spray drying method, a stirring granulation method, an impregnation method, and a kneading coating method. These granulation methods can be carried out with, for example, various known commercially available coating machines and granulators.

[0042] The secondary particles used for the production of three-dimensional objects contain a binding resin. The binding resin is used, for example, to bind the primary particles to each other.

[0043] - Adhesive resin -

[0044] The binding resin contained in the secondary particles contributes, for example, to binding the primary particles to each other, and again binds the surrounding ceramic particles after the binding resin is dissolved in the liquid when a liquid is dropped onto the binding resin.

[0045] The kind of adhesive resin is not particularly limited and can be suitably selected according to the intended purpose.The example of adhesive resin includes acrylic acid, maleic acid, silicone (organic silicon), butyral, polyester, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polyethylene, polypropylene, polyacetal, ethylene / vinyl acetate copolymer, ethylene / (methyl) acrylic acid copolymer, alpha-olefin / maleic anhydride copolymer, the esterification product of alpha-olefin / maleic anhydride copolymer, polystyrene, poly(methyl) acrylate, alpha-olefin / maleic anhydride / copolymer containing vinyl monomer, styrene / maleic anhydride copolymer, styrene / (methyl) acrylate copolymer, polyamide, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or rosin derivative, coumarone-indene resin, terpene resin, polyurethane resin, synthetic rubber such as styrene / butadiene rubber, polyvinyl butyral, nitrile rubber, acrylic rubber and ethylene / propylene rubber and nitrocellulose.Can use one of these adhesive resins alone, or can use two or more of these adhesive resins in combination.

[0046] The central particle diameter of the secondary particles is not particularly limited, can be appropriately selected according to the intended purpose, and is preferably 50 microns or less, more preferably 40 microns or less, and particularly preferably 30 microns or less. The lower limit of the central particle diameter of the secondary particles is preferably 100 nm or more, more preferably 500 nm or more, and particularly preferably 1 micron or more.

[0047] The central particle diameter of the secondary particles has the same meaning as the cumulative 50% volume diameter of the volumetric particle size distribution, and can be measured with, for example, a laser diffraction / scattering particle size measuring instrument (available from Horiba, Ltd., LA-300).

[0048] The content of the binder resin in the secondary particles is not particularly limited, can be appropriately selected according to the intended purpose, and is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, and particularly preferably 35% by mass or less in terms of preventing cracking, defect formation and deformation of the three-dimensional object. The lower limit of the content of the binder resin is preferably 1% by mass or more and more preferably 3% by mass or more.

[0049] The secondary particles must not be subjected to heat treatment, such as sintering.

[0050] The method for forming the powder layer is not particularly limited and may be appropriately selected according to the intended purpose. Examples of the method include a method using a known reverse rotation mechanism (reverse roller) adopted in the selective laser sintering method described in Japanese Patent No. 3607300, a method of spreading the powder into a thin layer with a member such as a brush, a roller, and a scraper, a method of pressing the surface of the powder with a pressing member to spread the powder into a thin layer, and a method using a known powder additive manufacturing device.

[0051] When a powder layer of secondary particles is formed on a support using, for example, a reverse rotating mechanism (reverse roller), a brush, a roller or a scraper or an extrusion member, the secondary particles are placed on a support set in an outer frame (also referred to as, for example, a "mold", a "hollow cylinder" or a "tubular structure") in such a manner that the support can move up and down while sliding relative to the inner wall of the outer frame to form a powder layer. When a support that can move up and down in the outer frame is used as the support, it is preferred to set the support at a position slightly lower than the upper end opening of the outer frame, that is, at a position lower by an amount corresponding to the thickness of the powder layer, and place the powder on the support.

[0052] The powder layer can be formed in an automatic and fast manner using a known powder additive manufacturing device. Typically, the powder additive manufacturing device includes a recoater configured to laminate a secondary particle layer, a movable (movable) supply tank configured to supply secondary particles to a support, and a movable forming tank in which the secondary particle layer is formed and laminated. The powder additive manufacturing device can set the surface of the supply tank to be slightly higher than the surface of the forming tank by lifting the supply tank, by lowering the forming tank, or by both. Therefore, the powder additive manufacturing device can place the secondary particles in the form of a layer and form a powder layer by starting the recoater from the supply tank side, and the powder layer can be laminated by repeatedly moving the recoater.

[0053] The average thickness of the powder layer is not particularly limited and may be appropriately selected depending on the intended purpose.The average thickness of each layer is preferably 10 micrometers or more but 200 micrometers or less, and more preferably 30 micrometers or more but 100 micrometers or less.

[0054] <Applying Step and Applying Unit>

[0055] The applying step is a step of applying a liquid for dissolving the binder resin to the layer formed in the forming step, and is performed by an applying unit.

[0056] In the application step, the binding resin contained in the secondary particles is dissolved to restore the secondary particles to the primary particles, so that the primary particles fill the gaps between the secondary particles. As a result, the area where the liquid is applied is solidified by the binding resin and is homogenized by the shape disintegration (shape disintegration) of the secondary particles. This makes it possible to reduce the gaps or unsolidified areas from the area where the liquid is applied. In addition, the roughness in the plane direction caused by the secondary particles can be reduced from the edge of the area where the liquid is applied. This makes it possible to manufacture objects with high precision.

[0057] The applying step is not particularly limited and may be appropriately selected depending on the intended purpose, as long as the applying step is a step of applying a liquid for dissolving the binder resin contained in the secondary particles to a predetermined area.

[0058] Examples of a method of applying a liquid to a predetermined area include a dispenser method, a spray method, and an inkjet method.

[0059] Among these methods, the dispenser method has excellent droplet quantification but has a small coating area coverage. The spray method can easily form a tiny jet of material and has a wide coating area coverage and excellent coating properties, but has poor droplet quantification and has the scattering of secondary particles due to the spray flow.

[0060] Therefore, the inkjet method is particularly preferred. The inkjet method is preferred because the inkjet method has better droplet quantitativeness than the spray method, a coating area coverage greater than the dispenser method, and can efficiently form a complex three-dimensional shape with good precision.

[0061] When the inkjet method is adopted, the application unit includes a nozzle, through which the liquid can be applied to the predetermined area by the inkjet method. The nozzle (discharge head) of a known inkjet printer can be suitably used as the nozzle, and the inkjet printer can be suitably used as the application unit. Preferred examples of inkjet printers include SG7100 available from Ricoh Company, Ltd. Inkjet printers are preferred because inkjet printers can achieve rapid coating, because inkjet printers can cause liquid to drip from the (discharge) head in large quantities at one time and coat a large area.

[0062] <<Liquid>>

[0063] The liquid is not particularly limited and may be appropriately selected depending on the intended purpose, as long as the liquid can dissolve the binder resin in the secondary particles.

[0064] The liquid contains a solvent, preferably a resin and inorganic particles, and further contains other components as necessary.

[0065] -Solvents-

[0066] The solvent is not particularly limited and can be appropriately selected according to the intended purpose. Examples of the solvent include water, alcohols containing two or more but seven or less carbon atoms, ketones containing three or more but eight or less carbon atoms, cyclic ethers and polyethers. One of these solvents can be used alone, or two or more of these solvents can be used in combination.

[0067] Examples of alcohols containing two or more but seven or less alcohols include ethanol, isopropanol, and n-butanol.

[0068] Examples of ketones containing three or more but eight or less carbon atoms include acetone and ethyl methyl ketone.

[0069] Examples of cyclic ethers include tetrahydrofuran.

[0070] Examples of polyethers include dimethoxyethanol and dimethoxydiglycol.

[0071] The content of the solvent in the liquid is not particularly limited and may be appropriately selected depending on the intended purpose.

[0072] When the liquid contains a resin, the solvent content in the liquid is preferably 60% by mass or more but 95% by mass or less, and more preferably 70% by mass or more but 90% by mass or less.

[0073] When the liquid contains no resin, the solvent content in the liquid is preferably 50% by mass or more but 99% by mass or less, and more preferably 70% by mass or more but 90% by mass or less.

[0074] The water content in the liquid is preferably as small as possible. The water content in the liquid is preferably less than 45% by mass and preferably less than 5% by mass.

[0075] -Resin-

[0076] Resin is not particularly limited and can be appropriately selected according to the intended purpose.The example of resin includes acrylic acid, maleic acid, silicone, butyral, polyester, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polyethylene, polypropylene, polyacetal, ethylene / vinyl acetate copolymer, ethylene / (methyl) acrylic acid copolymer, alpha-olefin / maleic anhydride copolymer, the esterification product of alpha-olefin / maleic anhydride copolymer, polystyrene, poly(methyl) acrylate, alpha-olefin / maleic anhydride / copolymer containing vinyl monomer, styrene / maleic anhydride copolymer, styrene / (methyl) acrylate copolymer, polyamide, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or rosin derivative, coumarone-indene resin, terpene resin, polyurethane resin, synthetic rubber such as styrene / butadiene rubber, polyvinyl butyral, nitrile rubber, acrylic rubber and ethylene / propylene rubber and nitrocellulose.One of these resins can be used alone, or two or more of these resins can be used in combination.

[0077] The resin may also be an organic or organometallic polymer compound having low hydrophilicity.

[0078] The resin content in the liquid is not particularly limited, may be appropriately selected depending on the intended purpose, and is preferably 5 mass % or more but 40 mass % or less and more preferably 10 mass % or more but 30 mass % or less in terms of controlling the viscosity of the liquid within a predetermined range.

[0079] -Inorganic particles-

[0080] It is preferred that the liquid contains inorganic particles having a central particle size that does not clog the nozzle. Since the inorganic particles are contained in the liquid, when the liquid is applied to a predetermined area of ​​the powder layer, the inorganic particles are placed in the gaps between the powder particles in the predetermined area. As a result, the density of the obtained three-dimensional object is increased.

[0081] It is preferred that the constituent material of the inorganic particles is the same as the raw material of the ceramic, and more preferred are zirconium oxide, aluminum oxide, mullite (aluminosilicate mineral), tungsten carbide, silicon carbide, silicon nitride, and aluminum nitride.

[0082] The central particle diameter of the inorganic particles is not particularly limited and may be appropriately selected depending on the intended purpose, as long as the central particle diameter of the inorganic particles is smaller than that of the ceramic raw material and is preferably 0.05 micrometers or more but 0.5 micrometers or less.

[0083] The central particle size of the inorganic particles has the same meaning as the particle size by volume based on the cumulative 50% of the particle size distribution by volume, and can be measured with, for example, a laser diffraction / scattering particle size measuring instrument (available from Horiba, Ltd., LA-300).

[0084] The content of the inorganic particles is not particularly limited, can be appropriately selected according to the intended purpose, and is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more, relative to the total amount of the liquid. The upper limit of the content of the inorganic particles is preferably 60% by mass or less and more preferably 50% by mass or less.

[0085] -Other components-

[0086] The other components are not particularly limited and may be appropriately selected depending on the intended purpose.Examples of the other components include a dispersant and a surfactant.

[0087] <Other steps>

[0088] The other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the other steps include a heat treatment step. Examples of the heat treatment step include drying, degreasing, and sintering.

[0089] Heat treatment can be performed in a manner suitable for the material. Because the green body produced typically has a characteristic shape, a pressurizing unit is typically not used to prevent shape collapse. Although pressure sintering (hot pressing) is often used in sintering, the present disclosure does not use pressure sintering and essentially assumes pressureless sintering.

[0090] In the present disclosure, a method of manufacturing a three-dimensional object as ceramic is to manufacture the three-dimensional object after raw materials of the three-dimensional object are temporarily bonded. For example, in this case, even when bonding is performed using a resin, only a small amount of resin is required for bonding, so that volume shrinkage caused by sintering can be suppressed. As a result, when a large structural component is manufactured, cracking of the component during sintering can be prevented, and thus a model having a size that can be used as, for example, a structural component in practice can be manufactured.

[0091] The manufacturing of a three-dimensional object of the green body formed by repeatedly performing the forming step and the applying step is completed in a state where the green body is buried in the powder.

[0092] At this time, the green body contains a large amount of solvent and thus has low strength and poor handleability. Therefore, the green body needs to be dried.

[0093] The layers can be dried layer by layer after the formation step and application step of each layer using, for example, an infrared heater.

[0094] The drying method is not particularly limited and any known method can be used. However, it is necessary to select a method that does not cause cracking or deformation according to the type of solvent. For example, when ethanol is used as a solvent, it is preferred that the green body is dried at 50 degrees Celsius for 24 hours.

[0095] The degreasing method is not particularly limited and any known method can be used. For example, when kaolin is used as the primary particles, the green body can be degreased appropriately by heat treating at 500 degrees Celsius for three hours in an atmosphere purged with nitrogen. However, the degreasing method is not limited to the above method.

[0096] The sintering method is not particularly limited and any known method can be used. It is preferred to sinter the green body at normal pressure to maximize the effect of the present disclosure. The atmosphere, heat treatment temperature and heat treatment time need to be adjusted according to the material. For example, when using aluminum oxide as the primary particle, heat treatment at 1,550 degrees Celsius for three hours in an argon atmosphere is suitable. Because the increase in heat treatment temperature can achieve densification but has disadvantages such as strength degradation and deformation due to the formation of coarse particles, it is necessary to optimize the conditions.

[0097] For example, as the sintering method, an electric current sintering method by, for example, pulse electric heating is suitable. However, the sintering method is not limited to this method.

[0098] (3D Object)

[0099] The three-dimensional object of the present disclosure is manufactured by the three-dimensional object manufacturing method of the present disclosure or the three-dimensional object manufacturing device of the present disclosure.

[0100] Applications of the three-dimensional object are not particularly limited and may be appropriately selected depending on the intended purpose. Application examples of the three-dimensional object include, for example, meters and operation panels of vehicles, office machines, electric and electronic machines, and cameras, various parts, daily necessities, and test products.

[0101] Examples of the three-dimensional object manufacturing method and the three-dimensional object manufacturing apparatus of the present disclosure will be described with reference to the drawings.

[0102] Figure 1 It is a conceptual drawing related to the manufacture of three-dimensional objects.

[0103] Figure 1 A three-dimensional object manufacturing apparatus 100 and a computer 103 are shown. The three-dimensional object manufacturing apparatus 100 comprises an object forming unit 101 and a post-processing unit 102.

[0104] In the three-dimensional object manufacturing, the computer 103 sends 3D data of the three-dimensional object to the object forming unit 101, and the object forming unit 101 forms the object based on the 3D data. Subsequently, the post-processing unit 102 applies post-processing such as heat treatment to complete the three-dimensional object.

[0105] Examples of a three-dimensional object manufacturing method and a three-dimensional object manufacturing apparatus will be described below.

[0106] Figure 21 is a flow chart showing an example of a process flow of a method for manufacturing a three-dimensional object. Figure 3 and 4A to 4F describe Figure 2 The process flow of the three-dimensional object manufacturing method of the present disclosure is shown.

[0107] Figure 3 is a functional block diagram illustrating an example of a three-dimensional object manufacturing apparatus.

[0108] Figure 3 The three-dimensional object manufacturing apparatus 100 includes an object forming unit 101 and a post-processing unit 102. The object forming unit 101 includes a forming unit 1 and an applying unit 2. The post-processing unit 102 includes a heat treatment unit 3.

[0109] 4A to 4F is a schematic diagram showing an example of a method for manufacturing a three-dimensional object.

[0110] In step S1 , the user inputs a repetition number to the three-dimensional object manufacturing apparatus 100 , and the flow moves to S2 .

[0111] In step S2 , the user inputs k=0 to the three-dimensional object manufacturing apparatus 100 , and the flow moves to S3 .

[0112] In step S3 , the three-dimensional object manufacturing apparatus 100 performs a forming step, and the flow moves to S4 .

[0113] Prior to the forming step, the secondary particles are granulated using primary particles containing a ceramic material and a binding resin (see Figure 4A ).

[0114] In the forming step, a powder layer is formed using secondary particles containing: primary particles containing a ceramic material; and a binding resin. The forming step can be performed using, for example, a forming unit.

[0115] like Figure 4B As shown, the forming unit includes, for example, a supply side powder storage tank 52 storing secondary particles 51, a forming side powder storage tank 54 in which a powder layer is formed, and a leveling mechanism 55. The supply side powder storage tank 52 includes a table 50 movable in the vertical direction. The forming side powder storage tank 54 includes a table 53 movable in the vertical direction. When a roller used as the leveling mechanism 55 moves from the supply side powder storage tank 52 to the forming side powder storage tank 54, the secondary particles 51 in the supply side powder storage tank 52 move to the forming side powder storage tank 54, and a powder layer 56 formed of the secondary particles 51 is formed on the table 53 (see Figure 4C ).

[0116] In step S4 , the three-dimensional object manufacturing apparatus 100 performs an applying step, and the flow moves to S5 .

[0117] In the applying step, a liquid for dissolving the binding resin is applied to the powder layer formed in the forming step to dissolve the binding resin contained in the secondary particles and restore the secondary particles to primary particles. The applying step is performed using, for example, an applying unit. Figure 4D As shown in FIG. 5 , the applying unit is, for example, an inkjet head 57. The inkjet head 57 applies a liquid 58 for dissolving the binder resin to a predetermined area of ​​the powder layer 56. Then, as shown in FIG. Figure 4E As shown, by dissolving the binding resin contained in the secondary particles to restore the secondary particles to the primary particles, gaps are formed between the secondary particles and the primary particles fill the gaps. As a result, the area where the liquid is applied is fixed by the binding resin and is uniformed by the shape collapse of the secondary particles, so that voids or uncured areas can be reduced from the area where the liquid is applied.

[0118] In step S5, k is incremented to k+1, and the flow moves to S6.

[0119] In step S6, the process moves to S3 when k is less than the repetition number, or moves to S7 when k is greater than or equal to the repetition number.

[0120] The forming step and the applying step are repeated until the number of laminated layers becomes the desired number. In this way, a layer-laminated structure is obtained on the stage 53. When the layer-laminated structure is dried, a Figure 4F A green body 59 is shown.

[0121] In step S7, the three-dimensional object manufacturing apparatus 100 performs a heat treatment step, and the process ends. In the heat treatment step, the dried green body is heated. The heat treatment step is performed using, for example, a heat treatment unit 3. Examples of the heat treatment unit 3 include a heater. For example, in the heat treatment step, the removal and decomposition of the resin and the sintering of the green body can be performed simultaneously.

[0122] In the above-described manner, a sintered body is obtained, which is a result of sintering the ceramic raw material.

[0123] Example

[0124] The present disclosure will be described below by way of examples. The present disclosure should not be construed as being limited to these examples.

[0125] (Examples 1 to 14)

[0126] according to Figure 2 The flowchart shown and 4A to 4F The three-dimensional object manufacturing method shown manufactures a three-dimensional object.

[0127] Powders prepared in the following manner using the materials listed in Table 1 below were used.

[0128] <Preparation of primary particles and secondary particles>

[0129] First, material particles (primary particles; particles of kaolin, titanium oxide, or aluminum oxide) having a predetermined central particle diameter shown in Table 1 and a binder resin (polyvinyl butyral (PVB)) are mixed in a solvent (ethanol) and sufficiently dispersed to prepare slurry.

[0130] Next, the obtained slurry is granulated into a droplet shape and dried using, for example, a spray granulator and a drying sintering furnace. The resultant is then classified as necessary to obtain secondary particles having a center particle diameter shown in Table 1.

[0131] Next, the secondary particles were sintered. The secondary particles have a three-dimensional structure in which tiny primary particles are bonded to each other while having voids. Therefore, the secondary particles have a nearly spherical shape. The primary particles of these samples have a size variation depending on, for example, the center particle diameter of the raw material particles.

[0132] The central particle diameters of the primary particles and the secondary particles were measured in the following manner.

[0133] -Measurement of the center particle size of primary and secondary particles-

[0134] The median particle size of the primary particles and the secondary particles is the particle size at which the cumulative 50% particle size distribution (D 50 ), which is obtained by measuring each particle with a laser diffraction / scattering particle size measuring instrument (obtained from Horiba, Ltd., LA-300).

[0135] <Liquid for dissolving adhesive resin>

[0136] Ethyl acetate used as a main solvent, SN DISPERSANT 5468 (available from San Nopco Limited) used as a dispersant, and the inorganic particles shown in Table 2 as required were added together and stirred for 24 hours. The resultant was used as a liquid for dissolving the binder resin.

[0137] <Object Creation>

[0138] Objects were fabricated using a rapid build lab apparatus obtained by rendering a binder-jet object fabrication apparatus (available from Desktop Metal, Inc.) partially solvent resistant.

[0139] The lamination interval of the layers was 100 micrometers. The object manufacturing model was a cube having a size of 10 mm×10 mm×10 mm. A liquid for dissolving the adhesive resin was applied to a desired area. The amount of the applied liquid was 600 dpi.

[0140] <Debinding and sintering>

[0141] Using an electric furnace, the object was degreased and sintered by increasing the temperature to each predetermined temperature within a range of 1,100 to 1,500 degrees Celsius at a rate of 5 degrees Celsius per minute, wherein each predetermined temperature was maintained for two hours, and then furnace cooling was performed.

[0142] Table 1

[0143]

[0144] Table 2

[0145]

[0146] The detailed information of the materials in Tables 1 and 2 are as follows.

[0147] -Primary particles-

[0148] *Kaolin 1: HYDRITE R obtained from Hayashi Kasei Co., Ltd., median particle size (D 50 ) is 5 microns

[0149] *Kaolin 2: HYDRITE SB 100 obtained from Hayashi Kasei Co., Ltd., with a median particle size (D 50 ) is 1 micron

[0150] *Kaolin 3: ECKALITE 1 obtained from Hayashi Kasei Co., Ltd., with a median particle size (D 50 ) is 500nm

[0151] *Titanium oxide 1: ST-01 obtained from Ishihara Sangyo Kaisha, Ltd., median particle size (D 50 ) is 10nm

[0152] *Titanium oxide 2: a custom product of ST SERIES obtained from Ishihara Sangyo Kaisha, Ltd., with a center particle size (D 50 ) is 50nm

[0153] * Alumina 1: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 5 microns

[0154] * Alumina 2: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50) is 500nm

[0155] - Adhesive resin -

[0156] *PVB (polyvinyl butyral, obtained from ESLEC B of Sekisui Chemical Co., Ltd.)

[0157] *Acrylic resin (acrylic polyol obtained from Taisei Fine Chemical Co. Ltd.)

[0158] -Inorganic particles-

[0159] * Mullite 1: a custom product from KCM Corporation's KM SERIES, with a center particle size (D 50 ) is 1 micron

[0160] * Mullite 2: a custom product from KM SERIES of KCM Corporation, with a center particle size (D 50 ) is 500nm

[0161] * Alumina A: AKP SERIES from Sumitomo Chemical Company, median particle size (D 50 ) is 1 micron

[0162] * Alumina B: AKP SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 50nm

[0163] (Comparative Examples 1 to 6)

[0164] The objects were manufactured by a common binder jetting method of manufacturing an object by repeatedly applying a liquid (pure water) to which polyvinyl alcohol (PVA) shown in Table 3 was added as a binder resin to a commercially available ceramic material (alumina or kaolin) shown in Table 3.

[0165] The inorganic particles shown in Table 3 were added to a liquid (pure water) to which polyvinyl alcohol (PVA) was added as a binder resin, as necessary.

[0166] In Comparative Examples 1 to 6, a commercially available product was used as the ceramic material. Therefore, secondary particles were not formed (primary particles).

[0167] Table 3

[0168]

[0169] The detailed information of the materials in Table 3 is as follows.

[0170] -Powder (primary particles)-

[0171] * Alumina 1: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 5 microns

[0172] * Alumina 3: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 50 microns

[0173] * Alumina 4: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 20 microns

[0174] * Alumina 5: AA SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 1 micron

[0175] *Kaolin 4: a product obtained by in-house (self-) granulation of HYDRITE SB 100S obtained from Hayashi Kasei Co., Ltd., with a median particle size (D 50 ) is 20 microns - Adhesive resin -

[0176] *PVA: SERVOL obtained from Sekisui Chemical Co., Ltd.

[0177] -Inorganic particles-

[0178] * Alumina B: AKP SERIES from Sumitomo Chemical Company, Limited, center particle size (D 50 ) is 50nm

[0179] Next, various properties of each of the obtained three-dimensional objects were evaluated in the following manner.

[0180] <Evaluation of the condition of three-dimensional objects after debinding and sintering>

[0181] Whether or not, for example, any abnormal deformation or cracking occurs in the three-dimensional object obtained through the degreasing and sintering steps is observed and evaluated according to the following criteria.

[0182] [Evaluation criteria]

[0183] B: No abnormal deformation such as twisting occurs.

[0184] C: Deformation such as twisting occurs which is difficult to recognize visually but can be measured by, for example, a length measuring device.

[0185] D: Visually noticeable deformation and cracking occurred.

[0186] <Arithmetic mean surface roughness Ra>

[0187] The surface roughness of each obtained three-dimensional object was measured as an index for evaluating the accuracy of the three-dimensional object. As the surface roughness, the arithmetic mean surface roughness Ra of each three-dimensional object surface was measured according to JIS B0601:2001, and evaluated according to the following criteria.

[0188] [Evaluation criteria]

[0189] A: The arithmetic mean surface roughness Ra is 30 micrometers or less.

[0190] B: The arithmetic mean surface roughness Ra is greater than 30 μm but 80 μm or less.

[0191] C: The arithmetic mean surface roughness Ra is greater than 80 μm but 100 μm or less.

[0192] D: The arithmetic mean surface roughness Ra is greater than 100 μm.

[0193] <Porosity>

[0194] The porosity of each three-dimensional object obtained was measured as an indicator for evaluating the smoothness of the three-dimensional object. The porosity was measured by the Archimedes method using a balance. Specifically, the weight of the solid was measured in the atmosphere (A), and then its weight in the replacement fluid (water) was measured (B). The porosity was calculated according to the following formula: [(B)-(A)] / (A)×100, and evaluated according to the following standards.

[0195] [Evaluation criteria]

[0196] A: The porosity is 1% or less.

[0197] B: The porosity is more than 1% but 10% or less.

[0198] C: The porosity is more than 10% but 20% or less.

[0199] D: The porosity is greater than 20%.

[0200] Table 4

[0201]

[0202] * In Table 4, "-" in the "arithmetic mean surface roughness" column and "-" in the "porosity" column of Comparative Example 6 indicate that the values ​​are not measurable.

[0203] Aspects of the present disclosure are, for example, as follows.

[0204] <1> A method for manufacturing a three-dimensional object using primary particles containing at least a ceramic material, the method comprising:

[0205] forming a layer using secondary particles containing primary particles and a binder resin, and

[0206] A liquid for dissolving the adhesive resin is applied to the layer formed in the formation.

[0207] The central particle size of the primary particles is 5 microns or less.

[0208] <2> according to <1> The three-dimensional object manufacturing method,

[0209] The central particle diameter of the primary particles is 0.01 micrometer or more but 1 micrometer or less.

[0210] <3> according to <1> or <2> The three-dimensional object manufacturing method,

[0211] The liquid contains inorganic particles.

[0212] <4> according to <3> The three-dimensional object manufacturing method,

[0213] The inorganic particles have a central particle diameter of 0.05 micrometers or more but 0.5 micrometers or less.

[0214] <5> according to <3> or <4> The three-dimensional object manufacturing method,

[0215] The content of the inorganic particles in the liquid is 20 mass % or more.

[0216] <6> according to <3> to <5> The three-dimensional object manufacturing method described in any one of the above,

[0217] The primary particles or inorganic particles contain at least one selected from the group consisting of aluminum oxide, silicon nitride, mullite, zirconium oxide, silicon carbide, tungsten carbide and aluminum nitride.

[0218] <7> according to <1> to <6> The three-dimensional object manufacturing method described in any one of the above,

[0219] The central particle size of the secondary particles is 50 microns or less.

[0220] <8> according to <7> The three-dimensional object manufacturing method,

[0221] The content of the binder resin in the secondary particles is 40% by mass or less.

[0222] <9> according to <1> to <8> The three-dimensional object manufacturing method described in any one of the above,

[0223] Wherein said applying comprises applying the liquid by inkjet method.

[0224] <10> according to <1> to <9> The three-dimensional object manufacturing method described in any one of the above further comprises volatilizing the liquid.

[0225] <11> A three-dimensional object manufacturing apparatus configured to manufacture a three-dimensional object using primary particles containing at least a ceramic material, the three-dimensional object manufacturing apparatus comprising:

[0226] a forming unit configured to form a layer using secondary particles containing primary particles and a binder resin, and

[0227] An applying unit configured to apply a liquid for dissolving the adhesive resin to the layer formed by the forming unit.

[0228] The central particle size of the primary particles is 5 microns or less.

[0229] <12> Three-dimensional objects, which are <1> to <10> A three-dimensional object manufacturing method according to any one of the preceding claims or according to <11> It is obtained by the three-dimensional object manufacturing equipment or both.

[0230] according to <1> to <10> The three-dimensional object manufacturing method according to any one of the above <11> The three-dimensional object manufacturing device and the <12> The three-dimensional object can solve various problems in the related art and achieve the purpose of the present disclosure.

Claims

1. A method for manufacturing a three-dimensional object using primary particles containing at least a ceramic material, the method comprising: forming a layer using secondary particles containing primary particles and a binder resin, and applying a liquid for dissolving the binder resin to the layer formed in the forming, The central particle size of the primary particles is 5 microns or less, The liquid contains inorganic particles and the central particle size of the inorganic particles is 0.05 micrometers or more but 0.5 micrometers or less, wherein the inorganic particles include at least one selected from alumina, silicon nitride, mullite, zirconium oxide, silicon carbide, tungsten carbide and aluminum nitride.

2. The method for manufacturing a three-dimensional object according to claim 1, The central particle diameter of the primary particles is 0.01 micrometer or more but 1 micrometer or less.

3. The method for manufacturing a three-dimensional object according to claim 1 or 2, The content of the inorganic particles in the liquid is 20 mass % or more.

4. The method for manufacturing a three-dimensional object according to any one of claims 1 to 2, The primary particles include at least one selected from the group consisting of aluminum oxide, silicon nitride, mullite, zirconium oxide, silicon carbide, tungsten carbide and aluminum nitride.

5. The method for manufacturing a three-dimensional object according to any one of claims 1 to 2, The central particle size of the secondary particles is 50 microns or less.

6. The method for manufacturing a three-dimensional object according to claim 5, The content of the binder resin in the secondary particles is 40 mass % or less.

7. The method for manufacturing a three-dimensional object according to any one of claims 1 to 2, Wherein said applying comprises applying the liquid by inkjet.

8. The method for manufacturing a three-dimensional object according to any one of claims 1 to 2, further comprising Allow the liquid to evaporate.

9. A three-dimensional object obtained by the three-dimensional object manufacturing method according to any one of claims 1 to 8.

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