Liquid composition, powder- liquid composition set, and production method

Abstract

A liquid composition includes a resin, a solvent A, and a solvent B. The solvent A has a polar term δP of less than 18 MPa1 / 2 and a hydrogen bond term δH of less than 16 MPa1 / 2 according to the Hansen solubility parameters. The solvent B has a polar term δP of 18 MPa1 / 2 or greater or a hydrogen bond term δH of 16 MPa1 / 2 or greater according to the Hansen solubility parameters. A boiling point of the solvent B is higher than a boiling point of the solvent A, and a mass ratio (X / Y), which is a ratio of a mass (X) of the solvent A to a mass (Y) of the solvent B, is 90 / 10 to 45 / 55.

Description

LIQUID COMPOSITION, POWDER- LIQUID COMPOSITION SET, AND PRODUCTION METHOD

[0001] The present disclosure relates to a liquid composition, a powder-liquid composition set, and a production method.

[0002] In recent years, as a method for producing an object having a complicated and finely detailed shape, an additive manufacturing method using a 3D printer has been actively developed. As a method for producing a three-dimensional object using a 3D printer, there is a method in which an object is formed by binder jetting (may be referred to as “BJ” hereinafter) and the formed object is sintered by a powder metallurgy technique.

[0003] For example, Patent Document 1 discloses a liquid composition that is used for 3D printing and includes a binder. Patent Document 1 discloses a configuration such that, for the purpose of shortening a time for the liquid composition to permeate a powder resin, the liquid composition includes a non-aqueous solvent having a boiling point of higher than 100℃ and lower than 175℃ in an amount of 0.1 percent by weight or greater and 5 percent by weight or less, in addition to water serving as a main solvent.

[0004] According to the existing liquid compositions, a liquid composition in an object evaporates while moving towards an opening (generally a top surface) of a building chamber during a drying step so that a large portion of the resin derived from the liquid composition is likely to be present on an upper surface side of a sintered compact, and a small portion of the resin is likely to be present on the bottom surface side of the sintered compact, causing resin segregation. Therefore, the existing liquid compositions have problems of sintering deformation.

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-000533

[0006] One aspect of the present disclosure aims to provide a liquid composition that can inhibit resin segregation at a drying step.

[0007] According to one aspect of the present disclosure, a liquid composition includes a resin, a solvent A, and a solvent B. The solvent A has a polar term δP of less than 18 MPa1 / 2and a hydrogen bond term δH of less than 16 MPa1 / 2according to the Hansen solubility parameters. The solvent B has a polar term δP of 18 MPa1 / 2or greater or a hydrogen bond term δH of 16 MPa1 / 2or greater according to the Hansen solubility parameters. A boiling point of the solvent B is higher than a boiling point of the solvent A. A mass ratio (X / Y), which is a ratio of a mass (X) of the solvent A to a mass (Y) of the solvent B, is 90 / 10 to 45 / 55.

[0008] According to one aspect of the present disclosure, there can be provided a liquid composition that inhibits resin segregation at a drying step.

[0009] Fig. 1 is a schematic view illustrating an object forming apparatus according to one embodiment of the present disclosure.Fig. 2A is a schematic cross-sectional view illustrating an object formation process flow in a method for producing a three-dimensional object according to one embodiment of the present disclosure.Fig. 2B is a schematic cross-sectional view illustrating the object formation process flow in the method for producing the three-dimensional object according to one embodiment of the present disclosure.Fig. 2C is a schematic cross-sectional view illustrating the object formation process flow in the method for producing the three-dimensional object according to one embodiment of the present disclosure.Fig. 2D is a schematic cross-sectional view illustrating the object formation process flow in the method for producing the three-dimensional object according to one embodiment of the present disclosure.Fig. 2E is a schematic cross-sectional view illustrating the object formation process flow in the method for producing the three-dimensional object according to one embodiment of the present disclosure.Fig. 3 is a schematic view illustrating an object forming system for the three-dimensional object according to one embodiment of the present disclosure.Fig. 4 is a flowchart illustrating the method for producing the three-dimensional object according to one embodiment of the present disclosure.Fig. 5 is a schematic view illustrating a measurement method according to one embodiment of the present disclosure.

[0010] Embodiments of the present disclosure will be described in detail hereinafter. The embodiments are not limited by the following description, and can be changed within a range that can be conceived by a person skilled in the art, such as replacements with other embodiments, additions, modifications, or deletions. All embodiments are included within the scope of the present disclosure, as long as the functions and effects of the present disclosure are exhibited.

[0011] In the present specification, a three-dimensional orthogonal coordinate system of three axial directions (X-axis direction, Y-axis direction, and Z-axis direction) is used. A width direction of an object forming apparatus is determined as the X-axis direction (or an X direction), a length direction of the object forming apparatus is determined as the Y-axis direction (or a Y direction), and a height direction of the object forming apparatus is determined as the Z-axis direction (or a Z direction). The direction from the bottom to top of the object forming apparatus is determined as a +Z-axis direction (plus Z-axis direction), and the opposite direction is determined as a -Z-axis direction (minus Z-axis direction). In the following description, the +Z-axis direction (plus Z-axis direction) may be referred to as up or above, and the -Z-axis direction (minus Z-axis direction) may be referred to as down or below, but such representations do not intend to represent a universal vertical relationship.

[0012] In the present specification, a numerical range represented by “to” indicates that numerical values described before and after the “to” are included as a lower limit and an upper limit, unless otherwise specified.

[0013] The terms used in the present specification are defined as follows.

[0014] In the present specification, the term “pre-debinding sintering precursor” is an object obtained by applying a liquid composition to a powder layer that has been formed by applying or depositing a metal particle-containing powder.

[0015] In the present specification, the term “post-debinding sintering precursor” refers to an object that is obtained by performing debinding to remove organic substances from the pre-debinding sintering precursor and is in a state before being subjected to sintering.

[0016] In the present specification, the term “sintered compact” refers to an object that is an integrated compact of a metal material derived from the metal particles and is an object obtained by sintering the post-debinding sintering precursor.

[0017] In the present specification, the term “three-dimensional object” mainly refers to an object obtained after completing all the steps. Accordingly, in the case where the method for producing the three-dimensional object does not include other steps after a sintering step, the “three-dimensional object” refers to an object obtained after the sintering step. In the case where the method for producing the three-dimensional object includes a post-processing step after the sintering step, the sintered compact that has been subjected to the post-processing step is a “three-dimensional object”. (Liquid composition)

[0018] The liquid composition of the present embodiment includes a solvent A, a solvent B, and a resin. The liquid composition may further include other components, such as a surfactant, an anti-drying agent, a viscosity modifier, a penetrating agent, a defoaming agent, a pH adjuster, an antiseptic agent, an anti-fungal agent, a colorant, a preservative, a stabilizer, and the like.

[0019] A boiling point of the solvent mixture including the solvent A and the solvent B is preferably 100℃ or higher and 250℃ or lower, and more preferably 140℃ or higher and 230℃ or lower. When the boiling point of the solvent mixture is 100℃ or higher and 250℃ or lower, favorable dischargeability of the liquid composition by an inkjet head, and favorable drying performance of the discharged liquid composition are achieved.

[0020] A total amount of the solvents in the liquid composition is preferably 60 percent by mass or greater and 95 percent by mass or less, and more preferably 70 percent by mass or greater and 90 percent by mass or less. When the total amount of the solvents in the liquid composition is 60 percent by mass or greater and 95 percent by mass or less, dischargeability of the liquid composition by an inkjet head and permeability of the liquid composition into a powder are improved. <HSP values of solvents>

[0021] The Hansen solubility parameters (HSP) are parameters belonging to common technical knowledge, and specific definitions and calculations are described, for example, in the following literature. Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007). The solubility parameter (HSP) values (δD, δP, and δH) of a solvent can be conveniently estimated from a chemical structure of the solvent, for example, using computer software Hansen Solubility Parameters in Practice (HSPiP).

[0022] The chemical structure of the solvent can be determined, for example, by gas chromatograph mass spectrometry (GCMS). A concentration of each solvent in the liquid composition can be determined by determining the chemical structure of each solvent included in a solvent mixture, and creating a calibration curve of a concentration of each solvent. In the present disclosure, the values registered in the database of HSPiP version 4.1.06 were used. In addition, a boiling point of each solvent was also determined using the values registered in the above database. <Solvent A>

[0023] As conditions for the solvent A, the polar term δP of the Hansen solubility parameter is less than 18 MPa1 / 2, and the hydrogen bond term δH of the Hansen solubility parameter is less than 16 MPa1 / 2.

[0024] In view of solubility of a resin, the polar term δP of the Hansen solubility parameter of the solvent A is less than 18 MPa1 / 2, preferably less than 10 MPa1 / 2, and more preferably 4.0 MPa1 / 2or greater and less than 8.5 MPa1 / 2.

[0025] In view of solubility of a resin, the hydrogen bond term δH of the solvent A is less than 16 MPa1 / 2, preferably less than 12 MPa1 / 2, and more preferably 4.0 MPa1 / 2or greater and less than 10 MPa1 / 2.

[0026] A boiling point of the solvent A is preferably 100℃ or higher and 200℃ or lower, more preferably 140℃ or higher and 190℃ or lower, and yet more preferably 180℃ or higher and 190℃ or lower. When the boiling point of the solvent A is 100℃ or higher and 200℃ or lower, dischargeability of the liquid composition by an inkjet head is improved, and favorable drying performance of the discharged liquid composition is also obtained.

[0027] An amount of the solvent A is preferably 30 percent by mass or greater and 85 percent by mass or less, more preferably 35 percent by mass or greater and 80 percent by mass or less, and yet more preferably 40 percent by mass or greater and 75 percent by mass or less, relative to a total amount of the liquid composition.

[0028] Examples of the solvent A include alcohols, esters, alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, and the like.

[0029] Examples of the alcohols include tetrahydrofurfuryl alcohol, cyclohexanol, 3-methoxy-3-methylbutanol, 3-methoxybutanol, 1-hexanol, 1-heptanol, 2-octanol, diacetone alcohol, 3, 3, 5-trimethyl-1-hexanol, and the like.

[0030] Examples of the esters include ethyl lactate, butyl lactate, ethylene glycol diacetate, propylene glycol diacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, dimethyl succinate, diethyl succinate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, cyclohexyl acetate, propyl acetate, butyl acetate, butyl propionate, 3-methoxybutyl acetate, and the like.

[0031] Examples of the alkylene glycol monoalkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and the like.

[0032] Examples of the alkylene glycol dialkyl ethers include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, dipropylene glycol dimethyl ether, and the like.

[0033] Among the above-listed examples, esters and alkylene glycol dialkyl ethers are preferable because a viscosity of a solution formed by dissolving a predetermined amount of a resin becomes low so that an amount of the resin added to the liquid composition can be increased, thereby improving strength of the pre-debinding sintering precursor.

[0034] Among the above-listed examples, moreover, ethylene glycol diacetate, propylene glycol monomethyl ether acetate, dimethyl malonate, ethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl acetoacetate, ethyl acetoacetate, 3-methoxybutyl acetate, propylene glycol diacetate, diethylene glycol dimethyl ether, butyl propionate, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, cyclohexyl acetate, and dipropylene glycol dimethyl ether are preferable in view of the Hansen solubility parameters and the boiling point of the solvent A.

[0035] The solvent A included in the liquid composition may be a single solvent or a solvent mixture including two or more solvents. In the case where the solvent A is a solvent mixture including two or more solvents, a mass of the solvent mixture is used as a mass of the solvent A.

[0036] A boiling point of the solvent mixture of two or more solvents can be determined by multiplying a value of a boiling point of each of the solvents by a molar fraction, and calculating a weighted average. <Solvent B>

[0037] According to the Hansen solubility parameters, the solvent B has the polar term δP of 18 MPa1 / 2or greater or the hydrogen bond term δH of 16 MPa1 / 2or greater. The polar term δP of the Hansen solubility parameter of the solvent B is preferably 18 MPa1 / 2or greater and 26 MPa1 / 2or less, and more preferably 18 MPa1 / 2or greater and 22 MPa1 / 2or less.

[0038] The hydrogen bond term δH of the solvent B is 16 MPa1 / 2or greater, preferably 16 MPa1 / 2or greater and 25 MPa1 / 2or less, and more preferably 16 MPa1 / 2or greater and 20 MPa1 / 2or less.

[0039] By setting the polar term δP of the solvent B or the hydrogen bond term δH of the solvent B to the above range, compatibility between solvents used as a solvent mixture and dissolution power with respect to a resin can be improved.

[0040] A boiling point of the solvent B is higher than the boiling point of the solvent A. The boiling point of the solvent B is preferably 100℃ or higher and 250℃ or lower, and more preferably 190℃ or higher and 250℃ or lower. When the boiling point of the solvent B is 100℃ or higher and 250℃ or lower, dischargeability of the liquid composition by an inkjet head is improved, and favorable drying performance of the discharged liquid composition is also obtained. The difference between the boiling point of the solvent B and the boiling point of the solvent A is preferably 15℃ or greater and 175℃ or less.

[0041] An amount of the solvent B is preferably 6 percent by mass or greater and 50 percent by mass or less, more preferably 8 percent by mass or greater and 45 percent by mass or less, and yet more preferably 10 percent by mass or greater and 40 percent by mass or less, relative to a total amount of the liquid composition.

[0042] Examples of the solvent B include alcohols, carbonates, and the like.

[0043] Examples of the alcohols include aliphatic alcohols, aromatic alcohols, and the like. Examples of the aliphatic alcohols include 2-propanol, 1, 2-hexanediol, 3-methyl-1, 5-pentanediol, ethylene glycol, 1, 3-propanediol, diethylene glycol, and the like.

[0044] Examples of the carbonates include ethylene carbonate, propylene carbonate, glycerol carbonate, and the like.

[0045] Among the above-listed examples, carbonates are more preferable because a viscosity of a solution formed by dissolving a predetermined amount of a resin becomes low so that an amount of the resin in the liquid composition can be increased, thereby improving strength of a pre-debinding sintering precursor.

[0046] Among the above-listed examples, propylene carbonate, 1, 2-hexanediol, 3-methyl-1, 5-pentanediol, and diethylene glycol are preferable in view of the Hansen solubility parameters and the boiling point of the solvent B.

[0047] The solvent B included in the liquid composition may be a single solvent or a solvent mixture including two or more solvents. In the case where the solvent B is a solvent mixture including two or more solvents, a mass of the solvent mixture is determined as a mass of the solvent B.

[0048] As a solvent mixture including the solvent A and the solvent B, any combination of the above-described solvents is selected. Examples of a preferable selection of the solvent A include ethyl acetoacetate, diethylene glycol diethyl ether, and the like. Examples of a preferable selection of the solvent B include propylene carbonate, ethylene carbonate, and the like.

[0049] A mass ratio (X / Y) of a mass (X) of the solvent A to a mass (Y) of the solvent B is 90 / 10 to 45 / 55. The mass ratio (X / Y) of the mass (X) of the solvent A to the mass (Y) of the solvent B is preferably 80 / 20 to 50 / 50, and more preferably 70 / 30 to 60 / 40. When a total of the mass (X) of the solvent A and the mass (Y) of the solvent B is determined as 100 and the mass (X) of the solvent A is larger than 90, resin segregation may become more significant in a pre-debinding sintering precursor. When a total of the mass (X) of the solvent A and the mass (Y) of the solvent B is determined as 100 and the mass (Y) of the solvent B is larger than 55, resin segregation may become more significant in a pre-debinding sintering precursor.

[0050] A method for calculating the mass ratio (X / Y) of the mass (X) of the solvent A to the mass (Y) of the solvent B in a liquid composition whose mass ratio (X / Y) is unknown is as follows. First, types and amounts of solvents included in the liquid composition are determined by GCMS or the like to classify the solvents into a group of one or more solvents corresponding to the solvent A and a group of one or more solvents corresponding to the solvent B. Then, a mass ratio (X / Y) is calculated from a mass (X) of the group of one or more solvents (e.g., a solvent mixture) corresponding to the solvent A and a mass (Y) of the group of one or more solvents (e.g., a solvent mixture) corresponding to the solvent B. As boiling points of the solvent A and the solvent B, a value of the solvent mixture is used in each group of the solvent A and the solvent B. <Viscosity>

[0051] A viscosity of the liquid composition at 25℃ is preferably 5 millipascal-seconds or greater and 50 millipascal-seconds or less, and more preferably 8 millipascal-seconds or greater and 30 millipascal-seconds or less. When the viscosity of the liquid composition is 5 millipascal-seconds or greater and 50 millipascal-seconds or less at 25℃, the liquid composition is stably discharged from a liquid composition applicator, such as an inkjet head or the like. Such accurate discharge of the liquid composition further improves bending strength of a pre-debinding sintering precursor and also improves dimensional accuracy of a sintered compact.

[0052] The liquid composition is substantially free from water. In the present specification, the phrase “substantially free from water” means that a water content of the liquid composition is 5.0 percent by mass or less. The water content of the liquid composition is preferably 3.0 percent by mass or less, yet more preferably 1 percent by mass or less, and particularly preferably zero, i.e. no water being included in the liquid composition. Since the liquid composition is substantially free from water, solubility of the resin is further improved, and the improvement in solubility of the resin can further reduce the viscosity of the liquid composition. In addition, formation of a hydrogel, in which a large amount of water is captured around the resin, is inhibited, and an increase in the viscosity of the liquid composition due to the hydrogel is inhibited. Therefore, the liquid composition can be suitably discharged, for example, by inkjet printing.

[0053] Since the liquid composition is substantially free from water, the liquid composition can be applied to a powder including inorganic particles, even when a material constituting the inorganic particles includes a highly active metal, i.e., a water-reactive substance, such as aluminum. As aluminum is brought into contact with water, a coating film of aluminum hydroxide is formed. If a large amount of water is included in the liquid composition, a density of a sintered compact is therefore reduced. However, reduction in the density of the sintered compact can be minimized by using the liquid composition that is substantially free from water. In addition, handling of aluminum is difficult because aluminum generates hydrogen when the aluminum comes into contact with water. By using the liquid composition that is substantially free from water, generation of hydrogen during production of an object can be inhibited. <Resin>

[0054] The resin is not particularly limited, and may be appropriately selected according to the intended purpose, as long as the resin functions as a binder with respect to the below-described metal particle-containing powder.

[0055] Examples of the resin include polyvinyl acetate, a partially-saponified polyvinyl acetate resin, a polyvinyl butyral resin, a styrene acrylic resin, a styrene maleic acid resin, a styrene maleic anhydride resin, a polyvinyl pyrrolidone resin, and the like.

[0056] Among the above-listed examples, the resin is preferably a partially-saponified polyvinyl acetate resin, a polyvinyl butyral resin, a styrene maleic acid resin, or a styrene maleic anhydride resin. When a partially-saponified polyvinyl acetate resin, a polyvinyl butyral resin, a styrene maleic acid resin, or a styrene maleic anhydride resin is used as the resin, strength of a pre-debinding sintering precursor can be improved.

[0057] An amount of the resin is preferably 5 percent by mass or greater and 40 percent by mass or less, more preferably 8 percent by mass or greater and 30 percent by mass or less, and yet more preferably 10 percent by mass or greater and 25 percent by mass or less, relative to a total amount of the liquid composition. When the amount of the resin is 5 percent by mass or greater and 40 percent by mass or less relative to a total amount of the liquid composition, strength of a pre-debinding sintering precursor is improved, and dischargeability of the liquid composition by an inkjet head and permeability of the liquid composition to a powder are improved. <Additives>

[0058] The liquid composition may appropriately include a surfactant, an anti-drying agent, a viscosity modifier, a penetrating agent, a defoaming agent, a pH adjuster, an antiseptic agent, an anti-fungal agent, a colorant, a preservative, a stabilizer, and the like according to the intended purpose.

[0059] A method for producing the liquid composition is not particularly limited, and may be appropriately selected according to the intended purpose. Examples of the method include a method in which constituent components are mixed and stirred, and the like.

[0060] The liquid composition of the present disclosure can be used for production of a three-dimensional object. The liquid composition of the present disclosure can be used for binder jetting. (Powder-liquid composition set)

[0061] The powder-liquid composition set of the present disclosure includes the liquid composition of the present disclosure and a powder including metal particles (may be referred to as a “metal particle-containing powder”).

[0062] In the powder-liquid composition set, the liquid composition and the metal particle-containing powder may be present in an integrated state, or may be independently present in a separate state. For example, a liquid composition container in which the liquid composition is accommodated and a powder container in which the metal particle-containing powder is accommodated may form an integrated member.

[0063] Even in the case where the liquid composition and the metal particle-containing powder are each independently accommodated in separate containers, such a configuration of the liquid composition and the metal particle-containing powder is also included in the powder-liquid composition set of the present disclosure as long as combinational use of the liquid composition and the metal particle-containing powder together is expected, or such combinational use is substantially guided. <Metal particle-containing powder>

[0064] The metal particle-containing powder includes metal particles, and may further include other components, as necessary. The metal particle-containing powder is a powder including metal particles. A three-dimensional object is produced by applying the liquid composition to a powder layer including the powder.

[0065] An angle of repose of the metal particle-containing powder is not particularly limited, and may be appropriately selected according to the intended purpose. The angle of repose of the metal particle-containing powder is preferably 60° or less, more preferably 50° or less, and yet more preferably 40° or less. When the angle of repose of the metal particle-containing powder is 60° or less, the metal particle-containing powder can be efficiently and stably disposed in a desired place of a building stage .

[0066] The angle of repose of the metal particle-containing powder can be measured, for example, by a powder characteristics tester (Powder Tester PT-N, manufactured by HOSOKAWA MICRON CORPORATION) or the like. -Metal particles-

[0067] The metal particles include at least one selected from the group consisting of particles formed of pure metals and particles formed of alloys. The metal particles are particles including a metal that serves as a constituent component of an object. The metal particles are not particularly limited as long as the metal particles include a metal, and may be particles formed of a pure metal or particles formed of an alloy. The metal particle-containing powder may be a powder containing metal particles of a pure metal and metal particles of an alloy.

[0068] The metal particles may include a non-metal element. A mass of a metal included in the metal particles is preferably 60.0 percent by mass or greater, more preferably 70.0 percent by mass or greater, yet more preferably 80.0 percent by mass or greater, and particularly preferably 90.0 percent by mass or greater, relative to a mass of the metal particles.

[0069] Examples of the metal that is a constituent component of the metal particles include aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), lead (Pd), silver (Ag), indium (In), tin (Sn), tantalum (Ta), tungsten (W), neodymium (Nd), an alloy of any of the foregoing metals, and the like. Among the above-listed examples, stainless (SUS) steel, iron (Fe), copper (Cu), silver (Ag), titanium (Ti), aluminum (Al), magnesium (Mg), or an alloy of the foregoing metals is suitably used, and pure aluminum (Al) or an aluminum (Al) alloy is more suitably used. The aluminum (Al) alloy preferably includes magnesium (Mg) or silicon (Si), or both magnesium (Mg) and silicon (Si).

[0070] An aluminum (Al) alloy including magnesium (Mg) has a low density and high specific strength, and therefore is commonly used in housing of electronic devices or parts for automobiles, for which having a light weight is important. However, the aluminum (Al) alloy including magnesium (Mg) has a problem that an oxidized film is easily formed. Conversely, in the method for producing the three-dimensional object of the present disclosure, an oxide film formed on the metal particles can be suitably thinned or removed by using the liquid composition of the present disclosure, even when the metal particles are formed of an alloy including magnesium (Mg). Thus, a density of a three-dimensional object can be improved.

[0071] In the case of an aluminum (Al) alloy including silicon (Si), when liquid phase sintering is performed as a method for sintering a sintering precursor, the silicon (Si) breaks through an oxide film of each metal particle and fills gaps between the metal particles with the silicon (Si), and therefore sintering between the metal particles is suitably progressed.

[0072] Examples of the aluminum alloy include AlSi10Mg, AlSi12, AlSi7Mg0.6, AlSi3Mg, AlSi1Mg, AlSi9Cu3, Toyal Scalmalloy (registered trademark) (AlMg4.5Sc0.7Zr0.3, manufactured by TOYO ALUMINUM K.K.), ADCl2, AlSi3, and the like. The above-listed examples may be used alone or in combination of two or more.

[0073] The metal particles can be produced by any method known in the related art. A method for producing the metal particles is not particularly limited. Examples of the method for producing the metal particles include: a pulverization method in which compression, impact, friction or the like is applied to a solid metal to pulverize the solid metal; an atomization method in which a molten metal is sprayed and rapidly cooled to obtain a powder; a precipitation method in which a component derived from a metal, which is dissolved in a liquid, is precipitated; a gas-phase reaction method in which a metal compound is vaporized, followed by precipitating a metal powder by crystallization. Among the above-listed examples, an atomization method is preferable as the method for producing the metal particles because obtained particles have spherical shapes and particle diameters with a narrow particle size distribution.

[0074] As the metal particles, a commercially available product may be used. Examples of the commercially available product include AlSi10Mg (Si10MgBB, manufactured by TOYO ALUMINUM K.K.), AlSi1Mg (Si1MgBB, manufactured by TOYO ALUMINUM K.K.), pure Al (A1070-30BB, manufactured by TOYO ALUMINUM K.K.), pure Ti (manufactured by OSAKA Titanium Technologies Co., Ltd.), SUS316L (product name: PSS316L, manufactured by Sanyo Special Steel Co., Ltd.), SiO2(product name: EXCELICA SE-15K, manufactured by Tokuyama Corporation), AlO2(product name: Taimicron TM-5D, manufactured by TAIMEI CHEMICALS CO., LTD.), ZrO2(product name: TZ-B53, manufactured by Tosoh Corporation), and the like.

[0075] A volume average particle diameter of the metal particles is not particularly limited, and may be appropriately selected according to the intended purpose. The volume average particle diameter is preferably 2 μm or greater and 100 μm or less, and more preferably 8 μm or greater and 50 μm or less. When the volume average particle diameter of the metal particles is 2 μm or greater, aggregation of the metal particles is inhibited, desirable production efficiency of the three-dimensional object is achieved, and handling the metal particles becomes easy. When the average particle diameter of the metal particles is 100 μm or less, decrease in contact points between the metal particles or increase in gaps between the metal particles can be inhibited so that sufficient strength of the three-dimensional object can be obtained.

[0076] The particle size distribution of the metal particles is not particularly limited, and may be appropriately selected according to the intended purpose. The particle size distribution is preferably sharper.

[0077] The volume average particle diameter and particle size distribution of the metal particles can be measured by any particle size analyzer known in the related art. Examples of the particle size analyzer include a particle size distribution analyzer (Microtrac MT3000II series, manufactured by MicrotracBEL Corp.) and the like. <Other components>

[0078] Other components included in the metal particle-containing powder are not particularly limited, and may be appropriately selected according to the intended purpose, as long as the effects of the present disclosure are not impaired. Examples of the other components include a filler, a leveling agent, a sintering aid, high molecular weight resin particles, and the like. The above-listed examples may be used alone or in combination of two or more. -Filler-

[0079] The filler is an effective material for treating surfaces of the metal particles through deposition of the filler on the surfaces of the metal particles or for filling gaps between the metal particles. Use of the filler can, for example, improve flowability of the powder, increase contact points between the metal particles, and reduce gaps between the metal particles. Therefore, strength or dimensional accuracy of a resultant three-dimensional object can be improved. -Leveling agent-

[0080] The leveling agent is a material effective for controlling wettability of a surface of a power layer. For example, use of the leveling agent increases permeability of the liquid composition to a powder layer, thereby increasing strength of a resultant three-dimensional object. -Sintering aid-

[0081] The sintering aid is an effective material for enhancing sintering efficiency when a sintering precursor is sintered. For example, use of the sintering aid can improve strength of a resultant three-dimensional object, lower a sintering temperature, and shorten a sintering time. -High molecular weight resin particles-

[0082] The high molecular weight resin particles are an effective material for treating surfaces of the metal particles through deposition of the high molecular-weight resin particles on the surfaces of the metal particles, and are also referred to as organic external additives. An average particle diameter of the high molecular weight resin particles is not particularly limited, and may be appropriately selected according to the intended purpose. The average particle diameter of the high molecular weight resin particles is preferably 0.1 μm or greater and 10.0 μm or less, and more preferably 0.1 μm or greater and 1.0 μm or less. (Method for producing three-dimensional object)

[0083] The method for producing the three-dimensional object includes (i) a powder layer forming step, (ii) a liquid composition applying step, and (iii) a laminating step. The (i) powder layer forming step includes forming of a powder layer including a metal particle-containing powder. The (ii) liquid composition applying step includes applying a liquid composition to the powder layer. The liquid composition includes a resin, a solvent A, and a solvent B. The solvent A has a polar term δP of less than 18 MPa1 / 2and a hydrogen bond term δH of less than 16 MPa1 / 2according to the Hansen solubility parameters. The solvent B has a polar term δP of 18 MPa1 / 2or greater or a hydrogen bond term δH of 16 MPa1 / 2or greater according to the Hansen solubility parameters, and has a boiling point higher than a boiling point of the solvent A. The (iii) laminating step includes repeating of the (i) powder layer forming step and the (ii) liquid composition applying step to obtain a pre-debinding precursor. In addition, the method for producing the three-dimensional object preferably further includes a drying step, a debinding step, and a sintering step, and may further include other steps, such as a surplus powder removing step and a post-processing step, as necessary. <Powder layer forming step>

[0084] The powder layer forming step is a step in which a powder layer including a metal particle-containing powder (may be simply referred to as a “powder” hereinafter) is formed. The details of the device for use will be described later.

[0085] A thickness of the powder layer is not particularly limited, and may be appropriately selected according to the intended purpose. An average thickness per layer is preferably 30 μm or greater and 500 μm or less, and more preferably 60 μm or greater and 300 μm or less. When the average thickness of the powder layer is 30 μm or greater, strength of an object obtained by applying the liquid composition to the powder is improved, and collapse of the shape of the object that may occur in the subsequent steps, such as a sintering step, can be inhibited. When the average thickness of the powder layer is 500 μm or less, dimensional accuracy of an object formed by applying the liquid composition to the powder can be improved.

[0086] In the present specification, the term “average thickness” of the powder layer refers to the mean of values of the thickness measured at three randomly selected points on the powder layer. <Liquid composition applying step>

[0087] The liquid composition applying step is a step that includes application of the liquid composition of the present disclosure to the powder layer.

[0088] A method for applying the liquid composition to the powder layer is preferably a method for discharging the liquid composition. The method for discharging the liquid composition is not particularly limited, and may be appropriately selected according to the intended purpose. Examples of the method for discharging include dispensing, spray coating, inkjet printing, and the like.

[0089] Among the above-listed examples, inkjet printing is preferably used. Since inkjet printing is used as the method for applying the liquid composition to the powder, an application amount of the liquid composition can be adjusted with high accuracy. <Laminating step>

[0090] The laminating step is a step that includes repeating of (i) the powder layer forming step and (ii) the liquid composition applying step sequentially, to obtain a pre-debinding precursor.

[0091] The laminating step includes the powder layer forming step and the liquid composition applying step. Thus, a region to which the liquid composition has been applied is formed in the powder layer. In addition, the laminating step includes a step that includes laminating the powder on the powder layer having the region to which the liquid composition has been applied (powder layer forming step), and a step that includes application of the liquid composition onto the powder layer (liquid composition applying step). Thus, a region to which the liquid composition has been applied is formed in the freshly laminated powder layer. The region to which the liquid composition has been applied in the powder layer laminated at the upper most portion is continuous to the region to which liquid composition has been applied in the powder layer immediately below. As a result, the integrated region, to which the liquid composition has been applied, having a thickness corresponding to two powder layers is obtained. <Drying step>

[0092] The drying step is a step in which the powder layer to which the liquid composition has been applied is heated. As a result, two or more organic solvents of the liquid composition or the like, which remain in the powder layer, are removed. At the drying step, a pre-debinding sintering precursor can be formed.

[0093] A heating temperature at the drying step is preferably a temperature equal to or lower than a boiling point of the organic solvents at 760 mmHg. Thus, the organic solvents or the like remaining in the powder layer can be vaporized and removed. If any organic solvent remains in the powder layer after the drying step, strength of a resultant pre-debinding sintering precursor may decrease. <Surplus powder removing step>

[0094] The surplus powder removing step is a step in which a surplus powder deposited on the pre-debinding sintering precursor is removed to obtain a three-dimensional object precursor (sintering precursor).

[0095] Examples of a method for removing the surplus powders include: a method in which the surplus powder is removed from the pre-debinding sintering precursor by a surplus powder removing device, such as an air blower, or the like; a method in which the surplus powder is removed from the pre-debinding sintering precursor by immersing the pre-debinding sintering precursor in a removal solution; and the like. <Debinding step>

[0096] The debinding step is a step in which debinding is performed on the powder layer to which the liquid composition has been applied. As a result, a sintering precursor from which organic substances derived from the liquid composition are removed can be obtained. The debinding step may vaporize and remove the removal solution, as well as removing the organic substances in the sintering precursor.

[0097] Examples of an atmosphere in which the debinding step is performed include a vacuum, an argon (Ar) atmosphere, a hydrogen (H2) atmosphere, a nitrogen (N2) atmosphere, and the like.

[0098] The debinding step includes increasing of the temperature that is equal to or lower than the boiling point of the organic solvents at 760 mmHg to a temperature equal to or higher than a decomposition temperature of the organic substances included in the powder layer. The debinding step preferably further includes heating of the sintering precursor at a temperature that is equal to or higher than the thermal decomposition temperature of the organic substances included in the powder layer, and lower than a melting point or solidus temperature of the material (metal) constituting the metal particles for a predetermined period. More preferably, the debinding step performs debinding at a temperature of 200℃ or higher and 570℃ or lower.

[0099] The solidus temperature can be appropriately selected according to the material constituting the metal particles. For example, in the case where AlSi10Mg particles are used, the solidus temperature is approximately 570℃.

[0100] The solidus temperature can be estimated by calculation of a phase diagram in thermodynamic equilibrium. <Sintering step>

[0101] The sintering step includes sintering of the sintering precursor that is the powder layer subjected to debinding (also referred to as a “post-debinding sintering precursor”). Thus, a sintered compact can be obtained. The debinding step and the sintering step may be continuously carried out.

[0102] The sintering step is, specifically, a step in which the sintering precursor is heated by a sintering device at a temperature that is equal to or higher than a solidus temperature of the metal material constituting the metal particles, and equal to or lower than a liquidus temperature of the metal material constituting the metal particles for a certain period to integrate and form a compact of the metal material.

[0103] More specifically, the sintering step includes heating of the post-debinding sintering precursor at a temperature between the liquidus temperature and the solidus temperature at 1 ℃ / h to 200 ℃ / h (heating speed can be changed during the step), followed by maintaining the temperature for 1 hour to 10 hours. After the sintering step, the inside of the sintering device is cooled, and a resultant object is taken out.

[0104] A specific maximum temperature reached in the sintering step is preferably a temperature at which a liquid phase of the metal material is generated by 10% to 50%.

[0105] Examples of an atmosphere in which the sintering step is performed include a vacuum, an argon (Ar) atmosphere, a hydrogen (H2) atmosphere, a nitrogen (N2) atmosphere, and the like.

[0106] The liquidus temperature can be appropriately selected according to the material constituting the metal particles. For example, in the case where AlSi10Mg particles are used, the liquidus temperature is approximately 600℃. The liquidus temperature can be estimated by calculation of a phase diagram in thermodynamic equilibrium.

[0107] The sintered compact has a high density. In the present specification, “the sintering compact having a high density” means that a relative density of the three-dimensional object (sintered compact) is high with respect to the density of the metal material constituting the three-dimensional object (sintered compact). The relative density of the three-dimensional object (sintered compact) is preferably 93% or greater, and more preferably 97% or greater.

[0108] Specifically, the relative density can be calculated according to the following equation. In addition, the density of the metal material and the density of the three-dimensional object (sintered compact) are measured, for example, by an automatic densitometer (manufactured by TOYO MACHINE MFG. CO., LTD.), and can be calculated according to the following equation. <Post-processing step>

[0109] The post-processing step is a step that includes post-processing of the sintered compact.

[0110] The post-processing is not particularly limited, and may be appropriately selected according to the intended purpose. Examples of the post-processing include a surface protective treatment, coating, and the like.

[0111] The method for producing the three-dimensional object can be suitably executed by the apparatus for producing the three-dimensional object of the present disclosure. (Embodiment of method for producing object)

[0112] Fig. 1 is a schematic view illustrating an object forming apparatus 100 according to one embodiment of the present disclosure.

[0113] The object forming apparatus 100 includes a powder layer forming device 1 and a liquid composition applicator 5. The powder layer forming device 1 is configured to form a powder layer 31 including a powder 20. The liquid composition applicator 5 is configured to apply a liquid composition 10 to the powder layer 31 to form a building layer 30. The object forming apparatus 100 is configured to laminate a plurality of building layers 30 to form an object.

[0114] The powder layer forming device 1 includes a powder tank 11 and a laminating device 16. The powder tank 11 includes a supply chamber 21, a building chamber 22, a supply stage 23, a building stage 24, and a surplus powder chamber 25. The powder tank 11 has a box shape. Upper planes of the supply chamber 21, the building chamber 22, and the surplus powder chamber 25 are open. The laminating device 16 includes a leveling roller 12 and a powder removing member 13.

[0115] The supply chamber 21 is a chamber for supplying the powder 20 to the building chamber 22. In addition, the supply chamber 21 is configured to accommodate the powder 20 to be supplied to the building chamber 22. The supply stage 23 is provided at the bottom of the supply chamber 21. The supply stage 23 is configured to be raised in the Z1 direction. The side surfaces of the supply stage 23 are disposed to be in contact with the inner side surfaces of the supply chamber 21.

[0116] The powder 20 to be used for forming an object is supplied from the supply chamber 21 to the building chamber 22. In the building chamber 22, powder layers 31 and building layers 30 are formed. Further, in the building chamber 22, an object in which a plurality of building layers 30 are laminated is formed.

[0117] The bottom of the supply chamber 21 and the bottom of the building chamber 22 are provided with the supply stage 23 and a building stage 24, respectively. The supply stage 23 and the building stage 24 are configured to be raised in the Z1 direction. The side surfaces of the building stage 24 are disposed to be in contact with the inner side surfaces of the building chamber 22. The upper surface of the supply stage 23 and the upper surface of the building stage 24 are both horizontally held.

[0118] The surplus powder chamber 25 is a chamber for accommodating a surplus powder 20 generated from the powder 20 leveled by the leveling roller 12 at the time of formation of the powder layer 31. The bottom of the surplus powder chamber 25 may be provided with a device that sucks the powder 20 or a mechanism for detaching the surplus powder chamber 25. The surplus powder chamber 25 is disposed adjacent to the building chamber 22. The surplus powder 20 in the surplus powder chamber 25 may be returned to the supply chamber 21, or may be returned to the supply chamber 21 via a powder supply device.

[0119] The powder supply device may be disposed above the supply chamber 21, and is configured to supply the powder 20 to the supply chamber 21 before the start of object formation, or when the amount of the powder 20 in the supply chamber 21 is low. In the embodiment that has been described above, the powder tank 11 has two chambers, which are the supply chamber 21 and the building chamber 22. However, the powder tank 11 may have only the building chamber 22, and a powder may be supplied from the powder supply device to the building chamber 22.

[0120] Examples of a method for transporting the powder 20 from the powder supply device to the supply chamber 21 include: a screw conveyer method using a screw; a pneumatic conveying method using air; and the like.

[0121] The leveling roller 12 is configured to level a building layer 30 or a powder layer 31. The leveling roller 12 includes a recoater as a rotating body. The building layer 30 is leveled by rotating the recoater. In addition, the leveling roller 12 is driven to rotate so that the powder 20 on the supply stage 23 of the supply chamber 21 is leveled off to supply the removed powder to the building chamber 22, thereby forming a powder layer 31.

[0122] The leveling roller 12 reciprocates in the Y direction along the plane of the building stage 24 (the surface on which the powder 20 is placed). More specifically, the leveling roller 12 horizontally moves from the outer side of the supply chamber 21, and passes above the supply chamber 21 and the building chamber 22. Thus, the powder 20 is transferred and supplied to the building chamber 22, and the supplied powder 20 is leveled to form a powder layer 31, as the leveling roller 12 passes above the building chamber 22. The leveling roller 12 is a member that is longer than the inner dimensions of the building chamber 22 and the supply chamber 21. A blade or bar may be used as a plate-shaped member of the leveling roller 12.

[0123] The powder removing member 13 is configured to remove the powder deposited on the leveling roller 12. The powder removing member 13 moves together with the leveling roller 12 in a state in which the powder removing member 13 is in contact with the circumferential surface of the leveling roller 12.

[0124] The liquid composition applicator 5 includes a carriage 51 and a head 52. The head 52 is configured to apply a liquid composition 10 to the powder layer 31. The head 52 is, for example, an inkjet head, and is provided with a nozzle array in which a plurality of nozzles are aligned. A color object may be formed by applying a cyan liquid composition, a magenta liquid composition, a yellow liquid composition, and a black liquid composition. Alternatively, a single-color liquid composition may be applied from a plurality of nozzles. A method for applying the liquid composition may be inkjet printing or dispensing. One or more heads 52 are mounted in the carriage 51, and are caused to reciprocate in the X (main scanning), Y (sub-scanning), and Z directions by a motor, a guide member, and the like.

[0125] Next, one embodiment (a process flow of object formation) of the method for producing the three-dimensional object of the present disclosure will be more specifically described with reference to Figs. 2A to 2E. Figs. 2A to 2E are schematic cross-sectional views illustrating an object formation process flow in the method for producing the three-dimensional object according to one embodiment of the present disclosure.

[0126] In Figs. 2A to 2E, the liquid composition applicator 5 and the surplus powder chamber 25 illustrated in Fig. 1 are omitted.

[0127] The description will start from the state in which a first building layer 30 is formed on the building stage 24 of the building chamber 22. When a subsequent building layer 30 is formed on the first building layer 30, as illustrated in Fig. 2A, the supply stage 23 of the supply chamber 21 is raised in the Z1 direction, and the building stage 24 of the building chamber 22 is lowered in the Z2 direction. For the above adjustment of the stages, the lowering distance of the building stage 24 is set so that a gap between the upper plane of the building chamber 22 (the surface of the powder layer) and the bottom of the leveling roller 12 (lower tangential portion) is to be Δt1. The gap Δt1 corresponds to a thickness of the subsequent powder layer 31 to be formed.

[0128] Next, as illustrated in Fig. 2B, the powder 20 in the supply chamber 21 is transferred and supplied to the building chamber 22 by moving the leveling roller 12 in the Y2 direction (to the building chamber 22 side) while rotating the leveling roller 12 in the forward direction (the direction of the arrow in Fig. 2B).

[0129] As illustrated in Fig. 2C, the leveling roller 12 is further moved in parallel to the surface of the building stage 24 of the building chamber 22 to form a powder layer 31 on the building stage 24 as illustrated in Fig. 2D. After forming the powder layer 31, the leveling roller 12 is returned to the initial position.

[0130] Thereafter, as illustrated in Fig. 2E, droplets of the liquid composition 10 are discharged from a liquid discharge head 52 to form and laminate a building layer 30.

[0131] Subsequently, the above-described powder layer forming step in which a powder layer 31 is formed, and the above-described liquid composition applying step using the liquid discharge head 52 are repeated to form a new building layer 30. The new building layer 30 and the previous building layer 30 below are integrated to form a part of a three-dimensional object.

[0132] Fig. 3 is a schematic view illustrating a three-dimensional object forming system according to one embodiment of the present disclosure.

[0133] The object forming system 500 according to one embodiment of the present disclosure includes an object forming apparatus 100, a heating device 200, a surplus powder removing device 300, and a sintering device 400. The object forming apparatus 100 is configured to form an object. The heating device 200 is configured to heat the object formed by the object forming apparatus 100. The surplus powder removing device 300 is configured to remove a surplus powder deposited on the object heated by the heating device 200. As the surplus powder removing device 300, for example, an air blower can be used. The sintering device 400 is configured to perform sintering of the object from which the surplus powder has been removed. The sintering device 400 may perform debinding of the object before sintering. The object forming system 500 may be configured by four separate devices, which are the object forming apparatus 100, the heating device 200, the surplus powder removing device 300, and the sintering device 400, or configured by one integrated device of the object forming apparatus 100, the heating device 200, the surplus powder removing device 300, and the sintering device 400. Alternatively, part of the functions of the object forming system 500 may be provided to the object forming apparatus 100 or the sintering device 400 to realize. In addition, at least part of functions of the heating device 200 or surplus powder removing device 300 may be appropriately omitted.

[0134] Fig. 4 is a flowchart illustrating the method for producing the three-dimensional object according to one embodiment of the present disclosure.

[0135] First, a powder layer including a powder is formed by the object forming apparatus 100 (S1). Next, the liquid composition is applied to the powder layer by the object forming apparatus 100 (S2). Formation of a powder layer and application of the liquid composition are sequentially repeated by the object forming apparatus 100, thereby forming an object (S3). Subsequently, the object formed at S3 is heated by the heating device 200 (S4). A surplus powder on the object heated at S4 is removed by the surplus powder removing device 300, thereby obtaining a three-dimensional object precursor (pre-debinding sintering precursor) (S5). Then, debinding of the three-dimensional object precursor (post-debinding sintering precursor) obtained at S5 is performed by the sintering device 400 (S6). Lastly, the post-debinding sintering precursor is sintered by the sintering device 400 (S7). (Three-dimensional object)

[0136] The three-dimensional object of the present disclosure is produced by the method for forming the three-dimensional object of the present disclosure or the apparatus for forming the three-dimensional object of the present disclosure. Thus, the three-dimensional object of the present disclosure has a high sintering density.

[0137] An application of the three-dimensional object is not particularly limited, and may be appropriately selected according to the intended purpose. For example, the three-dimensional object of the present disclosure can be suitably used for panels of meters or control units of automobiles, OA devices, electronic devices, or cameras, various parts, household items, prototypes, and the like.

[0138] Although the embodiments have been described above, the embodiments are merely presented as examples, and the present disclosure is not limited by the embodiments. The above embodiments can be performed in various other forms, and various combinations, omissions, deletions, modifications, and the like can be performed on the embodiments without departing from the scope of the present disclosure. The above embodiments and modifications of the above embodiments are included in the scope or gist of the present disclosure, and are also included in the invention defined in the claims and the scope of equivalents of the invention.

[0139] The present disclosure will be concretely described through Examples and Comparative Examples hereinafter, but the present disclosure is not limited by Examples and Comparative Examples below. (Example 1) <Preparation of liquid composition> <Method for producing liquid composition>

[0140] Eighty-one grams of ethyl acetoacetate (A0649, manufactured by Tokyo Chemical Industry Co., Ltd.), 9 g of propylene carbonate (P0525, manufactured by Tokyo Chemical Industry Co., Ltd.), and 10 g of polyvinyl acetate having a saponification degree of 10 mol% (JMR-10LL, manufactured by JAPAN VAM & POVAL CO., LTD.) were weighed and stirred by a magnetic stirrer for 4 hours while heating at 70℃. After stirring for 4 hours, heating was stopped, and stirring was continued until the temperature reached room temperature (25℃ ± 5℃), thereby obtaining a liquid composition. <Method for forming sintering precursor>

[0141] A powder of an aluminum alloy (AlSi10Mg, Si10Mg-30BB, manufactured by TOYO ALUMINUM K.K., volume average particle diameter: 35 μm) and the produced liquid composition were used to form a pre-debinding sintering precursor (30 mm (length) × 10 mm (width) × 3 mm (thickness)) using a binder jetting (BJ) device. <Drying step and surplus powder removing step>

[0142] The pre-debinding sintering precursor obtained at the laminating step was vacuum-dried at a temperature equal to or higher than the boiling point of the organic solvents at 760 mmHg by the drying device (drying step). After drying, the surplus powder was removed by the surplus powder removing device, thereby obtaining the pre-debinding sintering precursor from which the surplus powder had been removed (surplus powder removing step). <Debinding step and sintering step>

[0143] The pre-debinding sintering precursor was placed in a vacuum and pressurized sintering furnace (VESTA, manufactured by Shimadzu Corporation), and a non-vaporizing ZrVFe getter (TK707, manufactured by Nanjing Thanko Material Technology Co., Ltd.) serving as a gas adsorbent was arranged around the pre-debinding sintering precursor so that a weight per volume inside the furnace was 4.1 g / L.

[0144] The pressure inside the furnace was set to 1,000 Pa (10.0 mbar), and the furnace was heated at a temperature equal to or lower than a solidus temperature (approximately 570℃) of the metal material constituting the metal particles, thereby obtaining a post-debinding sintering precursor (debinding step). Thereafter, the furnace was heated at a temperature equal to or higher than the solidus temperature (approximately 570℃) of the metal material constituting the metal particles, and equal to or lower than a liquidus temperature (approximately 600℃) of the metal material constituting the metal particles, thereby obtaining a sintered compact (sintering step).

[0145] The solvents and resins used in Examples and Comparative Examples are as follows. Dimethyl malonate, M0030 manufactured by Tokyo Chemical Industry Co., Ltd. Diethyl malonate, M0029 manufactured by Tokyo Chemical Industry Co., Ltd. 3-Methyl-1, 5-pentanediol, M0710 manufactured by Tokyo Chemical Industry Co., Ltd. Diethylene glycol, D0495 manufactured by Tokyo Chemical Industry Co., Ltd. Ethylene carbonate, E0076 manufactured by Tokyo Chemical Industry Co., Ltd. Glycerol carbonate, G0279 manufactured by Tokyo Chemical Industry Co., Ltd. 2-Propanol, I0163 manufactured by Tokyo Chemical Industry Co., Ltd. 1, 2-Hexanediol, H0688 manufactured by Tokyo Chemical Industry Co., Ltd. Ethylene glycol, E0105 manufactured by Tokyo Chemical Industry Co., Ltd. 1, 3-Propanediol, P0486 manufactured by Tokyo Chemical Industry Co., Ltd. Styrene maleic acid resin, X-200 manufactured by CHEMIPAZ CORPORATION Styrene maleic anhydride resin, XIRAN4000 manufactured by Polyscope Polyvinyl butyral resin, S-LEC BL-10 manufactured by SEKISUI CHEMICAL CO., LTD. Polyvinyl pyrrolidone resin, P0471 manufactured by Tokyo Chemical Industry Co., Ltd. <<Method for measuring resin segregation>>

[0146] The resin segregation was measured in the following manner.

[0147] At the time of forming the pre-debinding sintering precursor, the upper surface of the pre-debinding sintering precursor (the plane in the size of 30 mm × 10 mm) in an amount of approximately 0.1 g was scraped by a spatula, and the collected portion was homogeneously ground and mixed to obtain a sample. The sample was weighed in an amount of 30 mg, and heated from 30℃ to 550℃ at a heating rate of 10 ℃ / min under a nitrogen gas flow of 200 mL / min by a thermal analyzer Thermoplus EVOII and thermogravimetry / differential thermal analyzer TG-DTA (manufactured by Rigaku Corporation). Thereafter, the amount of the resin in the upper surface sample was determined from the reduction in weight of the upper surface sample after maintaining the temperature at 550℃ for 20 minutes. Similarly, an amount of the resin in a lower surface sample was measured, and the value obtained by dividing the amount of the resin in the upper surface sample by the amount of the resin in the lower surface sample was determined as resin segregation.

[0148] The value of the resin segregation is preferably 3.5 or less, more preferably 3 or less, and yet more preferably 2.5 or less. <<Deformation amount of sintered compact>>

[0149] Fig. 5 is a schematic view illustrating a measurement method for a deformation amount of the sintered compact, and illustrates a cross-section of the sintered compact.

[0150] Fig. 5 illustrates the plane of the sintered compact whose sintering precursor had the size of 30 mm in length and 10 mm in width.

[0151] The deformation amount of the sintered compact was measured in the following manner. The thickness of the sample was measured at the center portion of the sample using a coolant proof micrometer MDC-25X (manufactured by Mitutoyo Corporation), and the obtained value was determined as A. Next, the entire thickness of the sample was measured by a digital caliper CD-15AX (manufactured by Mitutoyo Corporation), and the obtained value was determined as B. The value obtained by subtracting A from B was determined as the deformation amount.

[0152] An acceptable value of the deformation amount of the sintered compact is 0.1 mm or less.

[0153] The embodiments of the present disclosure were measured, for example, as follows. <<Method for measuring viscosity of liquid composition>>

[0154] The liquid composition was measured by a cone-plate rotary viscometer (VISCOMETER TVE-22L, manufactured by Toki Sangyo Co., Ltd.). The temperature inside the measuring container was fixed at 25℃ using a high-temperature circulation chamber, and a cone rotor (1°34’×R24) was used as a rotor. <<Method for measuring strength of pre-debinding sintering precursor>>

[0155] For the measurement of the strength of the pre-debinding sintering precursor, the sintering precursor having the size of 30 mm in length, 10 mm in width, and 3 mm in thickness was measured using a versatile tester (Autograph, model AG-I, manufactured by Shimadzu Corporation) with a 1 kN load cell and a three-point bending jig. In addition, the distance between the supporting points was set to 24 mm, the stress was plotted against the strain amount when the load point was deviated at the speed of 1 mm / min, and the stress at the breaking point was determined as a maximum stress. The stress of the pre-debinding sintering precursor refers to bending strength of the sintering precursor before the debinding step.

[0156] The stress value is preferably 3.0 MPa or greater, more preferably 4.0 MPa or greater, and more preferably 5.0 MPa or greater.

[0157] Hereinafter, the embodiment will be more specifically described through Examples and Comparative Examples, but the embodiment is not limited to Examples and Comparative Examples.

[0158] Examples in which a ratio of a mass of a solvent A to a mass of a solvent B was changed in the solvent mixture of ethyl acetoacetate and propylene carbonate are presented in Table 1.

[0159] Examples in which types of the solvents were changed from the solvents of Table 1 are presented in Tables 2 to 4.

[0160] Examples in which the type of the solvent B was changed while fixing the mass ratio A / B at 70 / 30 are presented in Table 5.

[0161] Examples in which the amount of the resin and the type of the resin were changed while fixing the mass ratio A / B at 70 / 30 are presented in Table 6.

[0162] This international application claims priority based on Japanese Patent Application No. 2025-27114 filed on February 21, 2025, the entire contents of which are incorporated herein by reference.

[0163] 1 powder layer forming device 5 liquid composition applicator 10 liquid composition (resin liquid) 11 powder tank 12 leveling roller 13 powder removing member 16 laminating device 20 powder 21 supply chamber 22 building chamber 23 supply stage 24 building stage 25 surplus powder chamber 30 building layer 31 powder layer 51 carriage 52 head Δt1 gap (laminating pitch) 100 object forming apparatus 200 heating device 300 surplus powder removing device 400 sintering device 500 object forming system

Claims

1. A liquid composition comprising: a resin; a solvent A; and a solvent B, wherein the solvent A has a polar term δP of less than 18 MPa1 / 2and a hydrogen bond term δH of less than 16 MPa1 / 2according to the Hansen solubility parameters, the solvent B has a polar term δP of 18 MPa1 / 2or greater or a hydrogen bond term δH of 16 MPa1 / 2or greater according to the Hansen solubility parameters, a boiling point of the solvent B is higher than a boiling point of the solvent A, and a mass ratio (X / Y), which is a ratio of a mass (X) of the solvent A to a mass (Y) of the solvent B, is 90 / 10 to 45 / 55.

2. The liquid composition according to claim 1, wherein the mass ratio (X / Y) is 80 / 20 to 50 / 50.

3. The liquid composition according to claim 1 or 2, wherein the solvent B has the polar term δP of 18 MPa1 / 2or greater according to the Hansen solubility parameter.

4. The liquid composition according to any one of claims 1 to 3, wherein the resin is included in an amount of 8 percent by mass or greater and 40 percent by mass or less relative to a total amount of the liquid composition.

5. The liquid composition according to any one of claims 1 to 4, wherein the liquid composition has a viscosity of 5 millipascal-seconds or greater and 50 millipascal-seconds or less at 25℃.

6. The liquid composition according to any one of claims 1 to 5, wherein the liquid composition is used for binder jetting.

7. A powder-liquid composition set, comprising: a powder including metal particles; and a liquid composition including a resin, a solvent A, and a solvent B, wherein the solvent A has a polar term δP of less than 18 MPa1 / 2and a hydrogen bond term δH of less than 16 MPa1 / 2according to the Hansen solubility parameters, the solvent B has a polar term δP of 18 MPa1 / 2or greater or a hydrogen bond term δH of 16 MPa1 / 2or greater according to the Hansen solubility parameters, a boiling point of the solvent B is higher than a boiling point of the solvent A, and a mass ratio (X / Y), which is a ratio of a mass (X) of the solvent A to a mass (Y) of the solvent B, is 90 / 10 to 45 / 55.

8. The powder-liquid composition set according to claim 7, wherein a water content of the liquid composition is 5.0 percent by mass or less.

9. The powder-liquid composition set according to claim 7 or 8, wherein the metal particles include aluminum.

10. A method for producing a three-dimensional object, the method comprising: (i) applying a powder including metal particles to form a powder layer; (ii) applying a liquid composition to the powder layer; and (iii) repeating (i) and (ii) to obtain a pre-debinding sintering precursor, wherein the solvent A has a polar term δP of less than 18 MPa1 / 2and a hydrogen bond term δH of less than 16 MPa1 / 2according to the Hansen solubility parameters, the solvent B has a polar term δP of 18 MPa1 / 2or greater or a hydrogen bond term δH of 16 MPa1 / 2or greater according to the Hansen solubility parameters, a boiling point of the solvent B is higher than a boiling point of the solvent A, and a mass ratio (X / Y), which is a ratio of a mass (X) of the solvent A to a mass (Y) of the solvent B, is 90 / 10 to 45 / 55.

11. The method according to claim 10, wherein (ii) includes applying the liquid composition using an inkjet head.

12. The method according to claim 10 or 11, further comprising: after (iii), sintering the pre-debinding sintering precursor.

13. The method according to any one of claims 10 to 12, wherein the resin is included in an amount of 8 percent by mass or greater and 40 percent by mass or less relative to a total amount of the liquid composition.

14. The method according to any one of claims 10 to 13, wherein the liquid composition has a viscosity of 5 millipascal-seconds or greater and 50 millipascal-seconds or less at 25℃.

15. The method according to any one of claims 10 to 14, wherein the metal particles include aluminum, and a water content of the liquid composition is 5.0 percent by mass or less.

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