Method for producing three-dimensional molded product, three-dimensional molded product, material powder for three-dimensional molding, and apparatus for molding three-dimensional molded product

Abstract

Provided is a material powder (C) for three-dimensional molding, in which a powder composition, which contains thermoplastic resin particles and a reinforcing filler and has a D50 particle diameter of 1-100 µm, contains a powder composition for imparting a thermal load at a temperature that is not lower than the crystallization temperature and not higher than the melting point of the thermoplastic resin, wherein the amount of fused aggregates is 1.0 mass% or less relative to the material powder (C). It is possible to provide: a three-dimensional molded product which excels in stable quality and reliability for a molded product even if a recycled material is molded, and which exhibits good uniform mechanical characteristics; and a method and apparatus for producing same.

Description

Method for manufacturing three-dimensional object, three-dimensional object, material powder for three-dimensional object, and three-dimensional object forming device

[0001] The present invention relates to a method for manufacturing a three-dimensional object, a three-dimensional object obtained thereby, a material powder for three-dimensional object manufacturing that is preferably used to obtain the three-dimensional object, and a three-dimensional object manufacturing apparatus used therefor.

[0002] Known technologies for manufacturing three-dimensional objects (hereinafter sometimes referred to as "models") include material extrusion, powder bed fusion, liquid vat photopolymerization, and sheet lamination. Among these, powder bed fusion involves forming layers of powder, selectively melting them at locations corresponding to the cross section of the object, and then bonding and laminating these layers to form a three-dimensional object. Methods for selectively melting powder include selective laser sintering, which uses a laser; selective absorption sintering, which uses a melting aid; and selective suppression sintering, which masks areas that should not be melted. Compared to other modeling methods, powder bed fusion has the advantage of being suitable for precision modeling because it does not require support members during modeling.

[0003] Taking advantage of their excellent mechanical properties and dimensional accuracy, the three-dimensional objects obtained by the above-mentioned method are being considered for use in a wide variety of fields, including mobility applications such as automobiles, aviation, and space, medical applications such as prosthetic limbs, braces, hearing aids, and catheters, sports applications, and electrical / electronic materials. In these applications, it is extremely important that the three-dimensional objects have a certain level of performance, that is, stable quality and reliability.

[0004] On the other hand, in powder bed fusion, most of the powder used does not become part of the molded object but is recovered as residual powder. It is preferable to reuse the residual powder in molding to reduce the amount of wasted powder (hereinafter, sometimes simply referred to as recycled molding). However, because the residual powder is exposed to a temperature slightly lower than its melting point for a long period of time during molding, it is denatured compared to unused, new powder, and there is a problem that the quality stability and reliability of three-dimensional molded objects obtained using it are reduced.

[0005] To address these issues, Patent Document 1 discloses a technology that uses polyamide 12 powder containing an antioxidant to prevent a defect phenomenon (called orange skin) in which the surface of a molded object becomes rough during recycling molding. Patent Document 2 discloses a technology that uses a branched polyamide powder to suppress an increase in the viscosity of polyamide during recycling molding.

[0006] JP 2010-189610 A JP 2011-514420 A

[0007] In the present invention, we have newly clarified that in the residual powder produced by powder bed fusion, a portion of the powder that has been subjected to thermal history forms fused aggregates of a specific size, which stochastically mix into the object produced during recycling modeling, affecting the quality stability of the object produced during recycling modeling.The technologies described in Patent Documents 1 and 2 can suppress the denaturation of material powder that occurs during three-dimensional modeling and reduce the difference in quality of objects produced using new powder and recycled powder, but they have been found to have issues with the quality stability of recycled objects.

[0008] Therefore, the present invention aims to provide a three-dimensional modeling technology that provides excellent quality stability and reliability of the modeled object even during recycled modeling, and exhibits good mechanical properties without variation, by subjecting a powder composition having a specific particle size to a thermal history equivalent to that of three-dimensional modeling and then removing the fused agglomerates.

[0009] To solve the above problems, the present invention has the following configurations: <1> A material powder (C) for three-dimensional printing, comprising a powder composition (A1) prepared by applying a thermal load to a powder composition containing thermoplastic resin particles and a reinforcing filler, the powder composition having a D50 particle size of 1 μm to 100 μm, at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin, wherein the content of fused agglomerates is 1.0 mass% or less based on the material powder (C). <2> The material powder for three-dimensional printing according to <1>, wherein the material powder (C) contains a powder composition (B) that has not been subjected to a thermal load in an amount of 0 parts by mass to 200 parts by mass per 100 parts by mass of the powder composition (A1). <3> The material powder for three-dimensional printing according to <2>, wherein the ratio (MwA) / (MwB) of the weight-average molecular weight of the thermoplastic resin constituting the powder composition (A1) to the weight-average molecular weight of the powder composition (B) is 1.0 to 2.0. <4> The material powder for three-dimensional modeling according to any one of <1> to <3>, wherein the sphericity of the thermoplastic resin particles is 80 to 100. <5> A method for producing a three-dimensional model, comprising: supplying to a three-dimensional modeling device a material powder (C) for three-dimensional modeling, the material powder (C) comprising a powder composition (A1) prepared by applying a thermal load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin to a powder composition having a D50 particle size of 1 μm to 100 μm, the powder composition containing thermoplastic resin particles and a reinforcing filler, the material powder (C) containing fused agglomerates at 1.0 mass% or less based on the material powder (C). <6> A method for producing a three-dimensional model according to <5>, comprising a step of removing fused agglomerates from the powder composition (A1) that has been applied a thermal load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin. <7> The method for producing a three-dimensionally shaped object according to <6>, wherein the step of removing fused agglomerates from the powder composition (A1) is a step of passing the powder composition through a filter having a mesh size that is two to six times the D50 particle size of the powder composition. <8> The method for producing a three-dimensionally shaped object according to any one of <5> to <7>, wherein the thermal load on the powder composition (A1) is due to three-dimensional modeling.<9> The method for producing a three-dimensionally shaped object according to any one of <6> to <8>, wherein a material powder (C) containing 0 to 200 parts by mass of a powder composition (B) that has not been subjected to a thermal load, the powder composition (B) containing particles of the thermoplastic resin and a reinforcing filler and having a D50 particle size of 1 μm to 100 μm, per 100 parts by mass of powder composition (A2) obtained by the step of removing fused agglomerates from powder composition (A1), is supplied to a three-dimensional modeling apparatus. <10> The method for producing a three-dimensionally shaped object according to any one of <5> to <9>, wherein the lightness of powder composition (A1) is 20 to 95. <11> The method for producing a three-dimensionally shaped object according to any one of <5> to <10>, wherein powder composition (A1) contains 5 to 60% by mass of a reinforcing filler, based on powder composition (A1). <12> A three-dimensionally shaped object formed using a material powder at least partly comprising a powder composition that has been subjected to a thermal load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of a thermoplastic resin that constitutes the powder composition, wherein the content of aggregates observed by X-ray CT observation of the object is 0.1 volume % or less. <13> The three-dimensionally shaped object according to <12>, which has a deflection temperature under load of 150°C or higher at 0.45 MPa. <14> The three-dimensionally shaped object according to <12> or <13>, which has a flexural modulus of elasticity of 3000 MPa or higher. <15> A three-dimensionally shaped object forming apparatus comprising the following means (a) to (c): (a) A means for filling a layer in which a material powder is to be formed into a model, and selectively melting and sintering the powder composition by applying thermal energy to melt the powder composition while applying a thermal load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of a thermoplastic resin constituting the powder composition of the material powder, (b) A means for recovering the powder composition that remains in the layer in which a model is to be formed without being melted and sintered, (c) A means for removing fused agglomerates from the recovered powder composition <16> The apparatus for forming a three-dimensional object according to <15>, further comprising the following means (d): (d) A means for mixing the recycled powder composition that has passed through the means for removing fused agglomerates of (c) with an unused powder composition <17> The apparatus for forming a three-dimensional object according to <15> or <16>, wherein the means for removing fused agglomerates of (c) is a means for passing the recovered powder composition through a filter having a mesh size of 2 to 6 times the D50 particle size of the powder composition.

[0010] According to the present invention, by removing fused aggregates of a specific size from a powder composition that has been given a thermal history equivalent to three-dimensional modeling, it is possible to obtain three-dimensional models that have excellent quality stability and reliability, even during recycled modeling, and that exhibit good mechanical properties without variation.

[0011] 1 is a schematic diagram showing an example of a manufacturing apparatus for a three-dimensional object according to the present invention; 2 is an X-ray CT observation photograph of the three-dimensional object obtained in Example 1; 3 is an X-ray CT observation photograph (A) of the three-dimensional object obtained in Comparative Example 1, and 4 is an enlarged photograph (B) of a part of the X-ray CT observation photograph;

[0012] The present invention will be described in detail below with reference to embodiments. Until now, quality assurance of three-dimensional objects has sometimes been an issue when applying them to industrial applications. In the manufacture of three-dimensional objects, unexpected variations in quality can occur even when material powders considered to be equivalent are used and objects manufactured using the same manufacturing data are manufactured. This invention newly clarifies that, in the residual powder produced by powder bed fusion, a portion of the powder that has been subjected to thermal history forms fused aggregates of a specific size, which stochastically mix into the object during recycling manufacturing, affecting the quality stability of the object manufactured during recycling manufacturing.

[0013] That is, the method for producing a three-dimensional object of the present invention is characterized by supplying to a three-dimensional printing device a material powder (C) for three-dimensional printing, the material powder (C) including a powder composition (A1) obtained by applying a heat load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin to a powder composition having a D50 particle size of 1 μm or more and 100 μm or less, the powder composition including thermoplastic resin particles and a reinforcing filler, the material powder (C) having a fused agglomerate content of 1.0 mass % or less based on the material powder (C).

[0014] The three-dimensional fabrication process using the powder bed fusion method of the present invention will be described below with reference to FIG.

[0015] In the first step, the stage 2 of the tank 1 in which the object is formed is lowered.

[0016] In the second step, the stage 4 of the tank 3 (hereinafter sometimes referred to as the supply tank), which has been previously filled with the material powder P to be supplied to the tank 1 where the molded object is formed, is raised to a height that allows for the supply of a sufficient amount of material powder P to fill the tank 1 with the specified layer height. Then, the recoater 5 is moved from the left end of the supply tank 3 to the right end of the tank 1, and the material powder P is layered in the tank 1. The direction parallel to the movement of the recoater 5 is the X direction, and the direction perpendicular to the direction of movement of the recoater 5 on the powder surface of the material powder P is the Y direction. Reference numeral 7 denotes a coordinate system representing the X direction, Y direction, and Z direction. Reference numeral 8 denotes the surface direction in which the material powder is layered, and reference numeral 9 denotes the height direction in which the material powder is layered.

[0017] In the third step, the material powder P filled into the tank 1 to a predetermined stack height in the second step is subjected to thermal energy 6 capable of melting, thereby selectively melting and sintering the material powder P in accordance with the molding data. Examples of selective melting and sintering methods include selective laser sintering, in which a laser is irradiated onto a shape corresponding to the cross-sectional shape of the object to be molded, thereby bonding the powder composition. Other examples include a printing process in which an energy absorption promoter or an energy absorption inhibitor is printed onto a shape corresponding to the cross-sectional shape of the object to be molded, and a selective absorption (or suppression) sintering process in which electromagnetic radiation is used to bond resin powder.

[0018] In the powder bed fusion method, the first to third steps are repeated to obtain a three-dimensional object 10, and the material powder that has been subjected to a thermal load at a temperature above the crystallization temperature and below the melting point of the thermoplastic resin remains in the tank 1.

[0019] The powder composition (A1) in the present invention is one that has been subjected to the above-mentioned thermal load. The method of applying the thermal load is not particularly limited as long as it is a known method, and it may be a method related to a three-dimensional modeling process or a treatment performed in advance in another process, but by using it for three-dimensional modeling, a thermal load of not less than the crystallization temperature and not more than the melting point of the thermoplastic resin that constitutes the powder is applied, so that the recycled powder composition used for three-dimensional modeling can be a powder composition that has been subjected to a thermal load.

[0020] The temperature of the heat load applied to the powder composition (A1) of the present invention is equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin constituting the powder. Preferably, since the heat load is related to the three-dimensional modeling process, if the temperature is lower than the crystallization temperature, the portion corresponding to the selectively melted shaped object will crystallize and warp will occur. Therefore, the lower limit of the temperature at which the heat load is applied is preferably crystallization temperature + 5 ° C or higher, more preferably crystallization temperature + 10 ° C or higher, even more preferably crystallization temperature + 15 ° C or higher, and particularly preferably crystallization temperature + 20 ° C or higher. The upper limit of the temperature at which the heat load is applied is preferably melting point - 5 ° C or lower, more preferably melting point - 10 ° C or lower, even more preferably melting point - 15 ° C or lower, and particularly preferably melting point - 20 ° C or lower, since if the temperature is higher than the melting point, the material powder other than the portion corresponding to the selectively melted shaped object will also melt.

[0021] The method for producing a three-dimensionally shaped object of the present invention is characterized in that the material powder (C) for three-dimensional modeling contains the powder composition to which the thermal load has been applied, and the content of fused agglomerates is 1.0 mass% or less based on the material powder (C). In the present invention, in order to ensure excellent quality stability and reliability of the shaped object and to exhibit good mechanical properties without variation even during recycled modeling, the content of fused agglomerates is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, even more preferably 0.03 mass% or less, and particularly preferably 0.01 mass% or less.

[0022] In the present invention, methods for reducing the amount of fused agglomerates to 1.0 mass % or less based on the material powder (C) include a method of carrying out a step of removing fused agglomerates, a method of performing three-dimensional modeling at a part bed temperature that is sufficiently low for the thermoplastic resin, and a method of using a material powder that contains sufficiently few fine thermoplastic resin particles and low-molecular-weight thermoplastic resin particles that cause fusion. However, the method of carrying out a step of removing fused agglomerates is preferred because it allows the fused agglomerates to be physically removed.

[0023] In the method for producing a three-dimensionally shaped object of the present invention, it is preferable to carry out a step of removing fused agglomerates from the powder composition (A1) to which a thermal load has been applied, followed by the three-dimensional modeling step. The method for removing fused agglomerates from the material powder is not particularly limited as long as it is a known method, and examples that can be used include a method of physically removing them using a filter with a specified mesh size, an airflow classification method in which compressed air is applied to separate them in a gas phase, and a method of separating them by using differences in buoyancy in a liquid phase. However, in terms of the precision of the separated size, a method of passing the agglomerates through a filter with a specified mesh size is more preferable.

[0024] In the present invention, the term "fused agglomerate" refers to a secondary agglomerate formed by the fusion of two or more primary particles when a thermal load is applied to a powder composition. The fused agglomerate contains thermoplastic resin particles and may also contain a reinforcing filler and a flow aid, which are preferably used in the present invention. Furthermore, in the present invention, "fused" refers to both a state in which multiple primary particles are fused and bonded together, and a state in which particles are surface-adhered to each other.

[0025] In the step of removing fused agglomerates according to the present invention, the content of fused agglomerates is preferably removed to 1.0% by mass or less based on the powder composition. Since the fewer fused agglomerates there are in the material powder used for three-dimensional modeling, the lower the probability of agglomerates being generated in the modeled object, the more preferably the content of fused agglomerates in the powder composition is 0.5% by mass or less, even more preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less, and extremely preferably 0.05% by mass or less.

[0026] In the present invention, the content of fused agglomerates is determined by a method in which fused agglomerates generated when a material powder is subjected to a thermal load are captured using a filter with a mesh size that allows removal, and the weight difference between the filter before and after passing through the filter is measured. The mesh size of the filter used to determine the content of fused agglomerates in the present invention is a nominal mesh size, as defined in Japanese Industrial Standards (JIS) JIS Z8801-1 (2006), of 4.6 to 5.4 times the D50 particle size of the powder composition. For example, a filter with a mesh size of 106 μm is used when the D50 particle size is 22 μm, a filter with a mesh size of 212 μm is used when the D50 particle size is 45 μm, a filter with a mesh size of 250 μm is used when the D50 particle size is 51 μm, and a filter with a mesh size of 300 μm is used when the D50 particle size is 60 μm.

[0027] The mesh size of the filter preferably used in the step of removing fused agglomerates of the present invention is 2 to 6 times the D50 particle size of the powder composition. The lower limit of the filter mesh size is more preferably 2.5 times or more, even more preferably 3 times or more, and particularly preferably 3.5 times or more, in terms of reducing the loss of material powder that can be normally molded. The upper limit of the filter mesh size is more preferably 5.5 times or less, even more preferably 5 times or less, and particularly preferably 4.5 times or less, in terms of improving the removal performance of fused agglomerates. A specific preferred size of the filter mesh size is 50 μm or more and 300 μm or less. Note that in the present invention, the mesh size of the filter used to determine the content of fused agglomerates and the mesh size of the filter preferably used in the step of removing fused agglomerates are different.

[0028] In the method for producing a three-dimensionally shaped object of the present invention, the three-dimensional modeling step is preferably carried out using material powder (C) containing 0 to 200 parts by mass of powder composition (B), which is a powder composition containing thermoplastic resin particles and a reinforcing filler and has a D50 particle size of 1 μm to 100 μm and has not been subjected to a thermal load, per 100 parts by mass of powder composition (A2), which has been subjected to a step of removing fused aggregates from powder composition (A1). It is more preferable that the powder composition (B) is the same as the powder composition (A1) before being subjected to a thermal load.

[0029] The upper limit of the proportion of powder composition (B) relative to 100 parts by mass of the powder composition (A2) is more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, particularly preferably 70 parts by mass or less, and particularly preferably 50 parts by mass or less, in terms of higher recyclability and less powder to be discarded. The lower limit is 0 parts by mass, which does not include powder composition (B).

[0030] As a method for mixing powder composition (A2) and powder composition (B), known methods can be used, such as a method of mixing by placing the powders in a mortar and stirring them with a pestle, a method of placing the powders in a container equipped with stirring blades and mixing them by stirring force, a method of placing the powders in a container that can rotate and revolve and mixing them by shaking force, etc. The method of mixing by shaking force is preferred because it allows uniform mixing without denaturing the powder compositions and is excellent in productivity.

[0031] The apparatus for forming a three-dimensional object of the present invention comprises the following means (a) to (c): (a) a means for filling a layer in which a material powder is to be formed into a model, and selectively melting and sintering the powder composition by applying thermal energy to melt the powder composition while applying a thermal load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin constituting the powder composition of the material powder, (b) a means for recovering the powder composition that remains in the layer in which a model is to be formed without being melted and sintered, and (c) a means for removing fused aggregates from the recovered powder composition (for example, a means for passing the recovered powder composition through a filter having a mesh size of 2 to 6 times the D50 particle size of the powder composition).

[0032] The means (a) to (c) may be separate apparatus sets, or two or three of them may be integrated into one apparatus, but from the viewpoint of improving work efficiency and saving space, an integrated apparatus is preferable. For example, an apparatus may be used in which a line for means (b) for recovering the powder composition is attached to means (a) for performing shaping, and the recovery line is attached to means (c) (for example, the filter as described above).

[0033] The apparatus for forming a three-dimensional object of the present invention preferably further comprises the following means (d): (d) a means for mixing a recycled powder composition that has passed through the means for removing fused agglomerates of the above (c) with an unused powder composition.

[0034] The means (d) may be a separate device set from the means (a) to (c) or an integrated device, but is preferably an integrated device from the viewpoint of improving work efficiency and saving space. For example, an example of such a device is one in which the recycled powder composition that has passed through the means (c) (e.g., a filter) in the recovery line (b) is introduced into a tank that supplies material powder, and is equipped with a means for mixing the recycled powder composition with unused powder composition by shaking or stirring.

[0035] The material powder used in the method for producing a three-dimensionally shaped object of the present invention includes a powder composition (A1) that contains thermoplastic resin particles with a sphericity of 80 to 100 and has a D50 particle size of 1 μm to 100 μm, and that has been subjected to a thermal load at a temperature equal to or higher than the crystallization temperature and lower than the melting point of the thermoplastic resin. The powder composition of the present invention will be described below.

[0036] The thermoplastic resin particles contained in the powder composition of the present invention are particles composed of a thermoplastic resin. The thermoplastic resin used in the present invention is a thermoplastic resin suitable for producing three-dimensional objects by powder bed fusion, and preferably includes polyethylene, polypropylene, polyester, polyamide, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyamideimide, polyethersulfone, polytetrafluoroethylene, or a mixture thereof. Polyester, polyamide, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyamideimide, polyethersulfone, and polytetrafluoroethylene are more preferred in terms of the heat resistance of the resulting three-dimensional objects. Polyester, polyamide, and polyphenylene sulfide are even more preferred in terms of the clear difference between the melting point and crystallization temperature, resulting in excellent formability and reproducibility. Polyamide is particularly preferred in terms of the excellent mechanical properties, such as toughness and strength, of the resulting objects.

[0037] Specific examples of polyamides preferably used in the present invention include polycaproamide (polyamide 6), polyundecaamide (polyamide 11), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polydecamethylene sebacamide (polyamide 1010), polydodecamethylene sebacamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sebacamide (polyamide 610), and polyhexamethylene dodecamide. Examples of the polyamide include polycaproamide (polyamide 612), polydecamethylene adipamide (polyamide 106), polydodecamethylene adipamide (polyamide 126), polyhexamethylene terephthalamide (polyamide 6T), polydecamethylene terephthalamide (polyamide 10T), polydodecamethylene terephthalamide (polyamide 12T), polycaproamide / polyhexamethylene adipamide copolymer (polyamide 6 / 66), and polycaproamide / polylauroamide copolymer (6 / 12). Among these, polycaproamide (polyamide 6), polyundecaamide (polyamide 11), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polydecamethylene sebacamide (polyamide 1010), polydodecamethylene sebacamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), and the like are preferred because they can be easily controlled to have a spherical shape. Furthermore, in terms of thermal properties suitable for molding, polycaproamide (polyamide 6), polyundecaamide (polyamide 11), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), polydecamethylene sebacamide (polyamide 1010), and polydodecamethylene sebacamide (polyamide 1012) are particularly preferred.Among these, polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), and polyhexamethylene sebacamide (polyamide 610) are particularly preferred in terms of their excellent heat resistance during modeling and the high deflection temperature under load of the resulting modeled object, and polycaproamide (polyamide 6) is the most preferred in terms of its thermal properties that make it less likely to produce aggregates during modeling.

[0038] The polyamide may be copolymerized to the extent that the effects of the present invention are not impaired. Examples of copolymerizable components include elastomer components such as polyolefins and polyalkylene glycols that impart flexibility, and rigid aromatic components that improve heat resistance and strength. Copolymerizable components that modify the end groups may also be used. Examples of such copolymerizable components include monocarboxylic acids such as acetic acid, hexanoic acid, lauric acid, and benzoic acid, and monoamines such as hexylamine, octylamine, and aniline.

[0039] The thermoplastic resin particles contained in the powder composition of the present invention may contain other additives as long as they do not impair the scope of the present invention. Examples of additives include antioxidants and heat stabilizers to suppress thermal degradation caused by heating during powder bed fusion molding. Examples of antioxidants and heat stabilizers include hindered phenols, hydroquinone, phosphites and their substituted derivatives, phosphites, and hypophosphites. Other additives include pigments and dyes for coloring, plasticizers for viscosity adjustment, flow aids for improving flowability, antistatic agents for functionalization, flame retardants, and fillers such as carbon black, silica, titanium dioxide, potassium titanate, glass fiber, glass beads, carbon fiber, and cellulose nanofibers. These additives may be known and may be present either inside or outside the thermoplastic resin particles.

[0040] The sphericity, which indicates the sphericity of the thermoplastic resin particles contained in the powder composition of the present invention, is preferably 80 to 100. If the sphericity is less than 80, the flowability deteriorates and the surface of the shaped product becomes rough. The sphericity is more preferably 85 to 100, even more preferably 90 to 100, particularly preferably 93 to 100, and most preferably 95 to 100.

[0041] The sphericity of the thermoplastic resin particles of the present invention is determined by observing 30 particles randomly selected from a scanning electron microscope photograph and determining the sphericity from their minor and major diameters according to the following formula.

[0042]

[0043] In the above formula, S is sphericity, a is major axis, b is minor axis, and n is the number of measurements (30).

[0044] The D50 particle size of the powder composition of the present invention is in the range of 1 to 100 μm. If the D50 particle size exceeds 100 μm, the particle size may exceed the stack height in three-dimensional modeling, resulting in a rough surface. If the D50 particle size is less than 1 μm, the particles are too fine and tend to adhere to a recoater or the like during modeling, making it impossible to raise the temperature of the modeling chamber to the required level. The upper limit of the D50 particle size of the powder composition is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less. The lower limit is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

[0045] The D50 particle size of the powder composition is the particle size (D50 particle size) at which the cumulative frequency from the small particle size side of the particle size distribution measured with a laser diffraction particle size distribution analyzer is 50%.

[0046] The weight-average molecular weight of the thermoplastic resin particles contained in the thermally loaded powder composition (A1) of the present invention is preferably in the range of 30,000 to 1,000,000. The higher the weight-average molecular weight, the slower the crystallization rate, which can suppress warping and other problems associated with crystallization during molding. Therefore, the lower limit is more preferably 40,000 or more, even more preferably 50,000 or more, particularly preferably 60,000 or more, significantly more preferably 65,000 or more, and most preferably 70,000 or more. If the molecular weight is too high, the viscosity increases, resulting in poor dispersibility and uniformity of the reinforcing material during molding. Therefore, the upper limit is more preferably 700,000 or less, even more preferably 500,000 or less, particularly preferably 300,000 or less, significantly more preferably 200,000 or less, and most preferably 100,000 or less.

[0047] The ratio (MwA) / (MwB) of the weight average molecular weight of the thermoplastic resin contained in the powder composition (A1) of the present invention to the weight average molecular weight of the thermoplastic resin contained in the powder composition (B) is preferably 1.0 or more and 2.0 or less. The upper limit of (MwA) / (MwB) is more preferably 1.8 or less, even more preferably 1.6 or less, and particularly preferably 1.5 or less, because a large difference in weight average molecular weights leads to non-uniform properties such as melt viscosity of the mixed material powder, which is undesirable. The lower limit is more preferably 1.1 or more, even more preferably 1.2 or more, and particularly preferably 1.3 or more, because higher molecular weights generally have better mechanical properties and increase in molecular weight when subjected to sufficient thermal load.

[0048] The weight average molecular weight of the thermoplastic resin constituting the thermoplastic resin particles refers to the value obtained by measuring the weight average molecular weight by gel permeation chromatography using a solvent that dissolves the thermoplastic resin, such as hexafluoroisopropanol, and converting it into polymethyl methacrylate.

[0049] The powder composition may be heat-treated in advance as long as the effects of the present invention are not impaired. Known heat-treatment methods can be used, including atmospheric heat treatment using an oven, reduced-pressure heat treatment using a vacuum dryer, and pressurized heat treatment in which the composition is heated together with water in a pressure vessel such as an autoclave. Heat treatment can be used to control the molecular weight, crystallinity, and melting point of the thermoplastic resin particles contained in the powder composition within desired ranges.

[0050] The powder composition of the present invention contains a reinforcing filler. The reinforcing filler is preferably contained in an amount of 5% by weight or more and 60% by weight or less. The upper limit of the amount of reinforcing filler is preferably 55% by weight or less, more preferably 50% by weight or less. The lower limit of the amount is preferably 10% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more. When the amount of reinforcing filler is 5% by weight or more, the elastic modulus and strength of a molded object obtained by three-dimensional molding of the powder composition can be improved. When the amount of reinforcing filler is 60% by weight or less, the flowability of the powder composition is not impaired, and molded objects with excellent surface smoothness tend to be obtained.

[0051] In the present invention, the reinforcing filler may be dry-blended with the thermoplastic resin particles or may be contained inside the thermoplastic resin particles, but it is preferable that the reinforcing filler be dry-blended in order to control the shape of the thermoplastic resin particles to a spherical shape and improve flowability.

[0052] Examples of such reinforcing fillers include glass-based fillers such as glass fiber, glass beads, glass flakes, and expanded glass beads; nepheline syenite fine powder, calcined clays such as montmorillonite and bentonite; clays (aluminum silicate powders) such as silane-modified clay; silica-containing compounds such as talc, diatomaceous earth, and silica sand; crushed natural minerals such as pumice powder, pumice balloons, slate powder, and mica powder; minerals such as barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, and graphite; silicas (silicon dioxides) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide); and alumina colloids (aluminum oxides). Examples of inorganic reinforcing materials include alumina such as Nasol, alumina white, calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, and special calcium carbonate-based fillers, fly ash spheres, volcanic glass hollow bodies, synthetic inorganic hollow bodies, single-crystal potassium titanate, potassium titanate fiber, carbon fiber, carbon nanotubes, carbon hollow spheres, fullerenes, anthracite powder, cellulose nanofibers, artificial cryolite (cryolite), titanium oxide, magnesium oxide, basic magnesium carbonate, dolomite, calcium sulfite, mica, asbestos, calcium silicate, molybdenum sulfide, boron fiber, and silicon carbide fiber. Glass-based fillers, minerals, and carbon fibers are preferred because of their hardness and significant strength-enhancing effect, and glass-based fillers are even more preferred because of their narrow particle size and fiber size distributions. These inorganic reinforcing materials can be used alone or in combination of two or more.

[0053] Examples of glass-based fillers preferably used in the present invention include glass fiber, glass beads, glass flakes, and foamed glass beads. Glass fiber, glass beads, or a mixture thereof are more preferred because they can impart a high elastic modulus to the three-dimensionally shaped object. Among these, glass fiber or a mixture of glass fiber and glass beads is particularly preferred because it can suppress warping of the shaped object. Furthermore, glass fiber is significantly preferred because it imparts high strength to the shaped object. Glass fiber may have a circular or flat cross section. Furthermore, glass beads are significantly preferred because they impart small anisotropy to the strength of the shaped object.

[0054] The average major axis diameter of the inorganic reinforcing material of the present invention is preferably in the range of 3 to 300 μm. An average major axis diameter exceeding 300 μm is undesirable because uneven polymer powder filling occurs when the material is molded, resulting in warpage of the molded product. Furthermore, surprisingly, a smaller average fiber length is preferable because it can reduce the amount of fused aggregates when used in recycling molding. An average major axis diameter of less than 3 μm is undesirable because it cannot contribute to warpage suppression. The upper limit of the average major axis diameter of the inorganic reinforcing material is preferably 250 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, particularly preferably 100 μm or less, extremely preferably 90 μm or less, and most preferably 60 μm or less. The lower limit is preferably 5 μm or more, more preferably 8 μm or more, even more preferably 10 μm or more, particularly preferably 20 μm or more, and extremely preferably 30 μm or more.

[0055] The shape characteristics of the inorganic reinforcing material of the present invention are expressed by the ratio of the average major axis diameter to the average minor axis diameter, i.e., the average major axis diameter / average minor axis diameter, and are preferably 1 to 15. A ratio of the average major axis diameter / average minor axis diameter exceeding 15 is undesirable because the orientation in the X direction of the shaped object becomes significant, increasing the anisotropy of warpage relative to the Z direction. Therefore, the average major axis diameter / average minor axis diameter is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less. Theoretically, the lower limit is 1. Among these, from the viewpoint of increasing strength, a ratio of 2 to 8 is particularly preferable, and a ratio of 3 to 8 is extremely preferable. From the viewpoint of reducing anisotropy, a ratio of 1 to 5 is particularly preferable, and a ratio of 1 to 3 is extremely preferable.

[0056] In the present invention, the average major axis diameter and the average minor axis diameter of an inorganic reinforcing material are the number average values ​​of the major axis diameter and the minor axis diameter of 100 randomly selected fibers or particles observed in a photograph obtained by photographing the inorganic reinforcing material with a scanning electron microscope. The major axis diameter is the diameter at which the distance between two parallel lines is the largest when the particle image is sandwiched between two parallel lines in a direction perpendicular to the major axis diameter, and the minor axis diameter is the diameter at which the distance between two parallel lines is the smallest when the particle image is sandwiched between two parallel lines in a direction perpendicular to the major axis diameter.

[0057] To improve the adhesion between the reinforcing filler and the thermoplastic resin particles, a surface-treated reinforcing filler can be used, provided that the effects of the present invention are not impaired. Examples of such surface treatments include silane coupling agents such as aminosilane, epoxysilane, and acrylicsilane. These surface treatment agents may be immobilized on the surface of the reinforcing filler by a coupling reaction or may coat the surface of the reinforcing filler. However, in terms of recycling the powder used in three-dimensional modeling, those immobilized by a coupling reaction are preferred because they are less likely to be modified by heat or the like.

[0058] The powder composition of the present invention preferably contains a flow aid to improve fluidity. A flow aid refers to a substance that suppresses powder aggregation due to adhesive forces between powder particles. The inclusion of such a flow aid improves the fluidity of the powder composition, i.e., improves the angle of repose, which is an index of fluidity described below, to a desired range, which tends to reduce defects that cause deterioration of mechanical properties and further improve the appearance of the resulting shaped product.

[0059] Examples of such flow aids include silica (silicon dioxide) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide), alumina colloid (alumina sol), and alumina white; calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, and special calcium carbonate-based fillers; titanium oxide, magnesium oxide, basic magnesium carbonate, potassium titanate fiber, boron fiber, and silicon carbide fiber. More preferred are silica, alumina, calcium carbonate powder, and titanium oxide. Particularly preferred is silica, which is hard and can contribute to improving strength and flowability.

[0060] Examples of commercially available silica products include the fumed silica "AEROSIL" (registered trademark) series manufactured by Nippon Aerosil Co., Ltd., the dry silica "Reolosil" (registered trademark) series manufactured by Tokuyama Corporation, and the sol-gel silica powder X-24 series manufactured by Shin-Etsu Chemical Co., Ltd.

[0061] The amount of such flow aid is preferably 0.01 wt% or more and 2.0 wt% or less based on the total weight of the powder composition. The upper limit of the amount is more preferably 1.5 wt% or less, even more preferably 1.0 wt% or less, particularly preferably 0.8 wt% or less, and extremely preferably 0.7 wt% or less. The lower limit of the amount is more preferably 0.02 wt% or more, even more preferably 0.03 wt% or more, and particularly preferably 0.04 wt% or more. When the amount of flow aid is 0.01 wt% or more, the fluidity of the powder composition is further improved, increasing the filling ability when shaped, thereby reducing the occurrence of voids that cause mechanical defects, and the resulting shaped product tends to exhibit high strength. When the amount of flow aid is 2.0 wt% or less, sintering is not inhibited due to the flow aid coating the surfaces of the thermoplastic resin particles, and shaped products with high strength tend to be obtained.

[0062] In the present invention, the lightness of the powder composition (A1) subjected to a thermal load is not particularly limited, but is preferably 20 or more and 95 or less, from the viewpoint of preventing color change during recycling molding and stabilizing the color tone of the molded product. The lower limit of the lightness is more preferably 50 or more, even more preferably 70 or more, and particularly preferably 80 or more, from the viewpoint of preventing color difference when the powder composition (B) is based on white. The upper limit is more preferably 92 or less, even more preferably 90 or less, and particularly preferably 88 or less, from the viewpoint that a low lightness reduces light absorption, makes it difficult to store heat during molding, and makes the molded product more likely to warp, which are undesirable.

[0063] The lightness in the present invention can be measured by a known method, for example, the L value measured using a spectrophotometer (SE2000) manufactured by Nippon Denshoku Industries Co., Ltd., with the powder composition filled in a petri dish.

[0064] The material powder for three-dimensional modeling of the present invention includes a powder composition (A2) obtained by subjecting a powder composition containing thermoplastic resin particles having a D50 particle size of 1 μm to 100 μm and a reinforcing filler to a thermal load at a temperature between the crystallization temperature and the melting point of the thermoplastic resin, and the material powder for three-dimensional modeling contains 1.0 mass% or less of fused agglomerates. In this invention, in order to ensure excellent quality stability and reliability of the molded product and good mechanical properties without variation even during recycling modeling, the content of fused agglomerates is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, particularly preferably 0.03 mass% or less, and extremely preferably 0.01 mass% or less.

[0065] The three-dimensional object of the present invention can be obtained by molding the material powder for three-dimensional molding of the present invention by powder bed fusion. The three-dimensional object of the present invention will be described below.

[0066] The three-dimensionally shaped object of the present invention is shaped using a powder composition containing at least a thermoplastic resin powder subjected to a thermal load at a temperature between the crystallization temperature and the melting point of the thermoplastic resin, and the content of aggregates observed by X-ray CT observation of the shaped object is 0.1 vol% or less. If the content of aggregates observed by X-ray CT observation exceeds 0.1 vol%, stress is concentrated in the aggregates, leading to reduced strength and reduced reliability such as fluid leakage when the shaped object is used as a container, which is undesirable. The content of aggregates is preferably 0.05 vol% or less, more preferably 0.02 vol% or less, even more preferably 0.01 vol% or less, and particularly preferably 0.005 vol% or less.

[0067] In the present invention, the content of aggregates was determined by X-ray CT observation of a disk-shaped object having a diameter of 40 mm and a thickness of 2 mm, with an image captured with a pixel size of 50 μm or less, detecting areas that had higher electron density than other areas and were observed as white bright spots as aggregates, and calculating the volume ratio of the aggregate content to the total observed area.

[0068] The deflection temperature under load of the three-dimensionally shaped object of the present invention at 0.45 MPa is preferably 150° C. or higher. The higher the deflection temperature under load, the less likely the shaped object is to deform in a high-temperature environment. Therefore, the deflection temperature under load of the shaped object is more preferably 170° C. or higher, even more preferably 185° C. or higher, and particularly preferably 200° C. or higher.

[0069] In the present invention, the deflection temperature under load is a value measured under a load of 0.45 MPa in accordance with the Japanese Industrial Standards (JIS) JIS K7191-1 (2015) "Plastics - Determination of deflection temperature under load" and the International Organization for Standardization (ISO) ISO 75-2.

[0070] The flexural modulus of the three-dimensionally shaped object of the present invention is preferably 3,000 MPa or more. The higher the flexural modulus, the more rigid and less likely the shaped object is to deform. Therefore, the flexural modulus of the shaped object is more preferably 3,500 MPa or more, even more preferably 4,000 MPa or more, particularly preferably 4,500 MPa or more, and most preferably 5,000 MPa or more. There is no particular upper limit, but since an excessively high modulus generally tends to make the object brittle and reduce its strength, the upper limit is preferably 20,000 MPa or less, more preferably 15,000 MPa or less, even more preferably 12,000 MPa or less, and particularly preferably 10,000 MPa or less.

[0071] In the present invention, the flexural modulus is a flexural modulus measured in accordance with the Japanese Industrial Standards (JIS) JIS K7171 (2016) "Plastics - Determination of flexural properties" and the International Organization for Standardization (ISO) ISO178 for a bending test piece formed in three-dimensional molding with the longest side oriented in the X direction.

[0072] The bending strength of the three-dimensionally shaped object of the present invention is preferably 65 MPa or more. Since the greater the bending strength, the more the object can withstand a force from the direction in which the greatest stress is applied, the bending strength of the object is more preferably 70 MPa or more, even more preferably 80 MPa or more, particularly preferably 90 MPa or more, extremely preferably 100 MPa or more, and most preferably 105 MPa or more.

[0073] In the present invention, the bending strength is determined in accordance with the Japanese Industrial Standards (JIS) JIS K7171 (2016) "Plastics - Determination of bending properties" and the International Organization for Standardization (ISO) ISO 178. The maximum bending stress is measured on a bending test piece shaped with the longest side facing the X direction.

[0074] Furthermore, compared to ordinary melt molding, three-dimensional objects are obtained by crystallization in a process of slowly lowering the temperature at normal pressure, and therefore the state of the crystals differs from that of ordinary melt molding. However, it is difficult to express this as a characteristic of the product, and therefore the object is limited by the manufacturing method, namely, three-dimensional molding, preferably by powder bed fusion. It is well known that with ordinary melt molding, highly reliable molded products can be obtained by careful consideration by those skilled in the art in accordance with the structure of the mold. However, with three-dimensional molding, which is capable of molding complex shapes, it has not been possible to obtain highly reliable molded products, and this has only been made possible by the present invention.

[0075] The present invention will be described below based on examples.

[0076] (1) D50 particle size of powder composition A dispersion prepared by dispersing about 100 mg of powder composition in about 5 mL of deionized water was added to a laser diffraction particle size distribution analyzer (Microtrac MT3300EXII) manufactured by Nikkiso Co., Ltd. until a measurable concentration was reached. After ultrasonic dispersion for 60 seconds at 30 W in the analyzer, the particle size at which the cumulative frequency from the small particle size side of the particle size distribution measured for 10 seconds was 50% was taken as the D50 particle size. The refractive index used during the measurement was 1.52, and the refractive index of the medium (deionized water) was 1.333.

[0077] (2) Sphericity of Thermoplastic Resin Particles The sphericity of the thermoplastic resin particles was calculated from the minor axis and major axis of 30 particles randomly selected from a photograph taken with a scanning electron microscope (JSM-6301NF) manufactured by JEOL Ltd., according to the following formula:

[0078]

[0079] In the above formula, S is sphericity, a is major axis, b is minor axis, and n is the number of measurements (30).

[0080] (3) Weight-average molecular weight of thermoplastic resin The weight-average molecular weight of the thermoplastic resin was calculated using gel permeation chromatography by comparing with a calibration curve using polymethyl methacrylate. The measurement sample was prepared by dissolving approximately 3 mg of thermoplastic resin particles in approximately 3 g of hexafluoroisopropanol. Apparatus: Waters e-Alliance GPC system Column: HFIP-806M x 2 manufactured by Showa Denko K.K. Mobile phase: 5 mmol / L sodium trifluoroacetate / hexafluoroisopropanol Flow rate: 1.0 mL / min Temperature: 30°C Detection: differential refractometer

[0081] (4) Lightness of Powder Composition The L value and color difference ΔE of the powder composition were measured using a spectrophotometer (SE2000) manufactured by Nippon Denshoku Industries Co., Ltd. The powder composition was added to a dedicated colorless and transparent quartz dish, and the dish was tightly packed while being vibrated, and then the measurement was performed.

[0082] (5) Measurement of Content of Fused Agglomerates in Material Powder (C) The content of fused agglomerates in material powder (C) was determined by passing 500 g of material powder (C) through a filter having a nominal mesh size, as defined in JIS Z8801-1 (2006), of 4.6 to 5.4 times the D50 particle size of powder composition (A1), weighing the mass trapped by the filter, and calculating the content as a percentage as the proportion of the amount of fused agglomerates present in 500 g.

[0083] (6) Measurement of aggregate content in the molded object The aggregate content in the molded object was measured using a 50 mm diameter, 2 mm thick disk-shaped molded object sample manufactured using a powder bed fusion 3D printer (RaFaElII 300-HT) manufactured by Aspect Inc. A ZEISS X-ray CT scanner (Xradia 510 Versa) was used to observe three-dimensional transmission images at a resolution of 45 μm, a field of view of 46 mm, a voltage of 80 kV, and a power of 7 W. Areas observed in the observed image as white bright spots with relatively high electron density were labeled, and the volume of the relevant area was divided by the total volume of the area corresponding to the molded object in the observed image. The value obtained was multiplied by 100 to determine the aggregate content in the molded object.

[0084] (7) Deflection temperature under load of the 3D object The deflection temperature under load of the 3D object was measured using a powder bed fusion 3D printer (RaFaElII 300-HT) manufactured by Aspect Co., Ltd. A test piece with a width of 10 mm, a length of 80 mm, and a thickness of 4 mm was prepared so that the 80 mm length direction was the X direction. The test piece was measured at a load of 0.45 MPa using a heat distortion tester (No. 148) manufactured by Yasuda Seiki Seisakusho Co., Ltd. in accordance with JIS K7191-1 (2015) and ISO75-2. The number of measurements was n = 3, and the average value was calculated.

[0085] (8) Measurement of flexural modulus and flexural strength of the 3D object The flexural modulus and flexural strength of the three-dimensional object were measured using a powder bed fusion 3D printer (RaFaElII 300-HT) manufactured by Aspect Inc. A test piece with a width of 10 mm, a length of 80 mm, and a thickness of 4 mm was prepared so that the 80 mm length was in the X or Z direction. The flexural modulus and flexural strength in the X and Z directions were measured using a Tensilon universal testing machine (TENSIRON TRG-1250) manufactured by A&D Co., Ltd. In accordance with JIS K7171 (2016) and ISO178, a three-point bending test was performed at a support distance of 64 mm and a test speed of 2 mm / min to determine the flexural modulus. The flexural strength was taken as the maximum bending stress. The measurement temperature was room temperature (23 ° C), the number of measurements was n = 10, and the average value was calculated.

[0086] (9) Evaluation of quality stability of the molded object The quality stability of the three-dimensional molded object was evaluated as good if the minimum value of the measurement was within 10% of the average value of n=10 of the bending strength measured in (8) above, and as poor if the difference was more than 10%.

[0087] [Production Example 1] A 3 L autoclave was charged with 360 g of ε-caprolactam (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polyamide monomer, 240 g of polyethylene glycol (primary polyethylene glycol 6,000, molecular weight 7,700, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymer incompatible with the resulting polyamide (2.5 g of antioxidant ("IRGANOX" (registered trademark) 1098, manufactured by BASF), and 50 g of deionized water, and the autoclave was sealed. This was followed by three cycles of pressurizing the vessel with nitrogen to 1 MPa and releasing the pressure to 0.1 MPa. The vessel was then purged with nitrogen, after which the pressure was adjusted to 0.1 MPa and the vessel was sealed. The stirring speed was then set to 60 rpm, and the temperature was raised to 230°C. The pressure inside the system was 1.4 MPa, and stirring was continued at 60 rpm for 3 hours while maintaining the pressure and temperature. Next, the pressure was released at a rate of 0.02 MPa / min to bring the internal pressure to 0 MPa. Then, the polymerization temperature was set to 210°C, and nitrogen was flowed at a rate of 5 L / min, allowing polymerization for 2 hours. Finally, the mixture was discharged into a 2000 g water bath to obtain a slurry. The slurry was thoroughly homogenized by stirring, and then filtered. 2000 g of water was added to the residue, and the residue was washed at 80°C. The slurry was then filtered again to remove coarse particles, and the isolated residue was dried at 80°C for 12 hours to produce 300 g of polyamide 6 powder. The resulting polyamide powder had a D50 particle size of 52 μm, a sphericity of 95, and a weight-average molecular weight of 54,000.

[0088] 14 kg of the polyamide 6 powder obtained by repeating the above steps was mixed with 6 kg of glass fiber EPG70M-01N (manufactured by Nippon Electric Glass Co., Ltd.) as a reinforcing filler. 60 g of trimethylsilylated amorphous silica X-24-9500 (manufactured by Shin-Etsu Chemical Co., Ltd., D50 particle size 170 nm) was further added as a flow aid to obtain powder composition (B). Using 20 kg of this powder composition (B), a three-dimensional object was manufactured using a powder bed fusion machine (RaFaElII 300-HT) manufactured by Aspect Corporation. The set conditions were 60WCO ２A laser was used, with a stacking height of 0.1 mm, a laser scanning interval of 0.1 mm, a laser scanning speed of 10 m / s, and a laser output of 17 W. The temperature settings were a part bed temperature of 208°C and a supply tank temperature of 177°C, and the heat load during modeling was applied for 15 hours. The resulting three-dimensional object had a good appearance, a flexural modulus of 5600 MPa, and a flexural strength of 112 MPa. The powder composition (A1) subjected to the heat load during the modeling process was recovered without forming a model. The D50 particle size of this powder composition (A1) was 51 μm, and the weight-average molecular weight (MwA) was 75,000.

[0089] [Production Example 2] 20 kg of powder composition (B) was obtained in the same manner as in Production Example 1, except that 12 kg of polyamide 6 powder was mixed with 8 kg of glass fiber EPG40M-01N (manufactured by Nippon Electric Glass Co., Ltd.) as a reinforcing filler. A three-dimensional object was produced in the same manner as in Production Example 1, except that the time for which a thermal load was applied during modeling was 8 hours, and the thermally loaded powder composition (A1) was recovered. This powder composition (A1) had a D50 particle size of 48 μm and a weight-average molecular weight (MwA) of 67,000.

[0090] [Production Example 3] Toray Industries, Inc.'s polyamide "Amilan (registered trademark)" CM1007 was pulverized for 120 minutes using a jet mill (Hosokawa Micron Corporation's 100AFG) to obtain pulverized polyamide 6 powder with a D50 particle size of 50 μm and a sphericity of 60. Three-dimensional modeling was performed in the same manner as in Production Example 1, except that this pulverized polyamide 6 was used, and the thermally loaded powder composition (A1) was recovered. The D50 particle size of this powder composition (A1) was 54 μm and the weight-average molecular weight (MwA) was 74,000.

[0091] [Production Example 4] 20 kg of powder composition (B) was obtained in the same manner as in Production Example 1, except that 14 kg of polyamide 6 powder was mixed with 6 kg of glass fiber EFH-150-01 (manufactured by Central Glass Co., Ltd.) as a reinforcing filler. A three-dimensionally shaped object was produced in the same manner as in Production Example 1, and the thermally loaded powder composition (A1) was recovered. This powder composition (A1) had a D50 particle size of 54 μm and a weight-average molecular weight (MwA) of 75,000.

[0092] Example 1: The powder composition (A1) obtained in Production Example 1 was passed through a 70-mesh filter with a wire diameter of 0.15 mm and a mesh size of 212 μm to remove fused aggregates, yielding powder composition (A2). 5.0 kg of this powder composition (A2) and 5.0 kg of powder composition (B) from Production Example 1 were loaded into a cross rotary mixer and mixed by shaking to obtain material powder (C). When 500 g of this material powder (C) was passed through a filter with a mesh size of 250 μm, the weight of the material captured by the filter was 0.02 g, or 0.004 mass%. Using 10 kg of this material powder (C), molding was performed under the same conditions as in Production Example 1, and the thermal load during molding was applied for 8 hours. The resulting three-dimensional molded object showed no aggregates in X-ray CT, and had a flexural modulus of 0.000 vol%, a flexural strength of 110 MPa, and a deflection temperature under load of 217°C. The bending strength was 110 MPa on average (n = 10) and 105 MPa at minimum (n = 10), and the quality stability was "good." Figure 2 shows an X-ray CT image of the sample used to observe the aggregates.

[0093] [Example 2] Powder composition (A1) obtained in Production Example 2 was passed through a 70-mesh filter with a wire diameter of 0.15 mm and a mesh size of 212 μm to remove fused aggregates, yielding powder composition (A2). 7.0 kg of powder composition (A2) and 3.0 kg of powder composition (B) from Production Example 2 were loaded into a cross rotary mixer and mixed by shaking to obtain material powder (C). When 500 g of material powder (C) was passed through a filter with a mesh size of 250 μm, the weight of the material captured by the filter was 0.04 g, or 0.008 mass%. A three-dimensionally shaped object was produced using material powder (C). X-ray CT of the resulting three-dimensionally shaped object revealed 0.000 vol% aggregates, a flexural modulus of 7200 MPa, a flexural strength of 113 MPa, and a deflection temperature under load of 218°C. The bending strength was 113 MPa on average (n=10) and 107 MPa at minimum (n=10), and the quality stability was "good."

[0094] [Example 3] Powder composition (A1) obtained in Production Example 3 was passed through a 50-mesh filter with a wire diameter of 0.21 mm and a mesh size of 300 μm to remove fused aggregates, yielding powder composition (A2). 5.0 kg of this powder composition (A2) and 5.0 kg of powder composition (B) from Production Example 3 were loaded into a cross rotary mixer and mixed by shaking to obtain material powder (C). When 500 g of this material powder (C) was passed through a filter with a mesh size of 250 μm, the weight of the material captured by the filter was 0.3 g, or 0.06 mass%. A three-dimensionally shaped object was produced using this material powder (C). X-ray CT of the resulting three-dimensionally shaped object revealed 0.03 vol% aggregates, a flexural modulus of 5,300 MPa, a flexural strength of 111 MPa, and a deflection temperature under load of 215°C. The bending strength was 111 MPa on average (n=10) and 102 MPa at minimum (n=10), and the quality stability was "good."

[0095] Comparative Example 1: A material powder (C) was prepared in the same manner as in Example 1, except that the powder composition (A1) obtained in Production Example 1 was used without passing it through a filter. When 500 g of this material powder (C) was passed through a filter with a mesh size of 250 μm, the weight of the material captured by the filter was 5.52 g, or 1.1 mass%. A three-dimensional object was produced using this material powder (C). X-ray CT of the resulting three-dimensional object revealed that the aggregates were 0.2 vol%, the flexural modulus was 5,300 MPa, the flexural strength was 108 MPa, and the deflection temperature under load was 217°C. The flexural strength was an average of 108 MPa (n = 10) and a minimum of 94 MPa (n = 10), indicating that the quality stability was "poor." X-ray CT images of the sample used for observing the aggregates are shown in Figures 3(A) and 3(B).

[0096] [Comparative Example 2] The powder composition (A1) obtained in Production Example 4 was passed through a 16-mesh filter with a wire diameter of 0.59 mm and a mesh size of 1000 μm to remove fused aggregates, yielding powder composition (A2). 5.0 kg of this powder composition (A2) and 5.0 kg of powder composition (B) from Production Example 4 were loaded into a cross rotary mixer and mixed by shaking to obtain material powder (C). When 500 g of this material powder (C) was passed through a filter with a mesh size of 250 μm, the weight of the material captured by the filter was 9.26 g, or 1.9 mass%. A three-dimensionally shaped object was produced using this material powder (C). X-ray CT of the resulting three-dimensionally shaped object revealed 0.8% by volume of aggregates, a flexural modulus of 4400 MPa, a flexural strength of 103 MPa, and a deflection temperature under load of 213°C. The bending strength was 103 MPa on average (n=10) and 85 MPa at minimum (n=10), and the quality stability was "poor."

[0097] The three-dimensionally shaped object of the present invention has excellent quality stability and reliability, and exhibits consistent and favorable mechanical properties even when recycled. The three-dimensionally shaped object obtained by the method for producing a three-dimensionally shaped object of the present invention can be effectively used in mobility applications requiring high reliability, such as automobiles, aviation, and space, medical applications such as prosthetic limbs, braces, hearing aids, and catheters, and electrical appliance applications such as home appliances and power tools, and can have an optimally designed three-dimensionally shaped object with a complex shape.

[0098] REFERENCE SIGNS LIST 1 Tank for forming object 2 Tank stage for forming object 3 Supply tank pre-filled with powder composition to be supplied 4 Tank stage pre-filled with powder composition to be supplied 5 Recoater 6 Thermal energy 7 X, Y, Z coordinate system 8 Plane direction for laminating powder composition 9 Height direction for laminating powder composition 10 Three-dimensional object P Material powder

Claims

1. A material powder (C) for three-dimensional modeling, comprising: a powder composition (A1) which contains thermoplastic resin particles and a reinforcing filler and has a D50 particle size of 1 μm or more and 100 μm or less, and which is subjected to a heat load at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin, and which remains without being melted and sintered in a layer in which a model is to be formed, wherein the material powder (C) for three-dimensional modeling contains fused agglomerates of 1.0 mass% or less based on the material powder (C).

2. 2. The material powder for three-dimensional modeling according to claim 1, wherein the material powder (C) contains a powder composition (B) to which no thermal load has been applied in an amount of 0 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the powder composition (A1).

3. 3. The material powder for three-dimensional modeling according to claim 2, wherein the ratio (MwA) / (MwB) of the weight average molecular weight of the thermoplastic resin constituting the powder composition (A1) to the weight average molecular weight of the powder composition (B) is 1.0 or more and 2.0 or less.

4. The material powder for three-dimensional modeling according to claim 1 , wherein the sphericity of the thermoplastic resin particles is 80 or more and 100 or less.

5. A method for producing a three-dimensional object, comprising the steps of: applying a heat load to a powder composition having a D50 particle size of 1 μm or more and 100 μm or less, the powder composition containing thermoplastic resin particles and a reinforcing filler, at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin; and supplying the material powder (C) for three-dimensional modeling, the material powder (C) comprising a powder composition (A1) that remains without being melted and sintered in a layer in which a model is to be formed, the material powder (C) having a fused agglomerate content of 1.0 mass% or less based on the material powder (C), to a three-dimensional modeling device.

6. 6. The method for producing a three-dimensional object according to claim 5, further comprising a step of applying a thermal load at a temperature equal to or higher than the crystallization temperature and lower than the melting point of the thermoplastic resin, and removing fused agglomerates from the powder composition (A1) that remains in the layer in which the object is to be formed without being melted and sintered.

7. 7. The method for producing a three-dimensional object according to claim 6, wherein the step of removing fused agglomerates from the powder composition (A1) is a step of passing the powder composition through a filter having an opening that is 2 to 6 times the D50 particle size of the powder composition.

8. The method for producing a three-dimensional structure according to claim 5 , wherein the thermal load on the powder composition (A1) is due to three-dimensional modeling.

9. 7. The method for producing a three-dimensional object according to claim 6, wherein a material powder (C) containing 0 parts by mass or more and 200 parts by mass or less of a powder composition (B) to which no thermal load has been applied, the powder composition (B) containing particles of the thermoplastic resin and a reinforcing filler and having a D50 particle size of 1 μm or more and 100 μm or less, per 100 parts by mass of the powder composition (A2) obtained by performing a step of removing fused agglomerates from the powder composition (A1), is supplied to a three-dimensional printing apparatus.

10. The method for producing a three-dimensional structure according to claim 5 , wherein the lightness of the powder composition (A1) is 20 or more and 95 or less.

11. The method for producing a three-dimensional object according to claim 5 , wherein the powder composition (A1) contains a reinforcing filler in an amount of 5% by mass to 60% by mass based on the powder composition (A1).

12. A three-dimensional object is formed using a material powder that is subjected to a thermal load at a temperature above the crystallization temperature and below the melting point of the thermoplastic resin that constitutes the powder composition, and that contains at least a portion of the powder composition that remains without being melted and sintered in the layer that forms the object, wherein the three-dimensional object has an aggregate content of 0.1 volume % or less as observed by X-ray CT observation of the object.

13. The three-dimensional structure according to claim 12 , having a deflection temperature under load of 150° C. or higher at 0.45 MPa.

14. The three-dimensional structure according to claim 12, having a flexural modulus of elasticity of 3000 MPa or more.

15. A three-dimensional object forming apparatus comprising the following means (a) to (c): (a) A means for selectively melting and sintering a material powder by filling the layer in which the shaped object is to be formed with the material powder and selectively melting and sintering the powder composition by applying a thermal load at a temperature equal to or higher than the crystallization temperature and lower than the melting point of the thermoplastic resin constituting the powder composition of the material powder. (b) A means for recovering the powder composition remaining in the layer in which the object is to be formed without being melted and sintered. (c) a means for removing fused agglomerates from the recovered powder composition.

16. The apparatus for forming a three-dimensional object according to claim 15, further comprising the following means (d): (d) a means for mixing the recycled powder composition that has been passed through the means for removing fused agglomerates of (c) with a virgin powder composition.

17. The three-dimensional object molding apparatus according to claim 15, wherein the means for removing the fused agglomerates in (c) is a means for passing the recovered powder composition through a filter having a mesh size that is 2 to 6 times the D50 particle size of the powder composition.