Method for producing powder composition, powder composition, method for producing three-dimensional shaped article, and three-dimensional shaped article

Abstract

A manufacturing method of a powder composition, the powder composition being a powder composition for a powder additive manufacturing method, the manufacturing method having the following (a) step to (b) step: (a) step, 0.2 to 50 parts by weight of carbon black having an absorption amount of DBP (dibutyl phthalate) of 10 ml / 100 g or more and 500 ml / 100 g or less with respect to 100 parts by weight of thermoplastic resin particles are mixed to obtain a premixed powder (P1), (b) step, thermoplastic resin particles are additionally mixed in the premixed powder (P1) in a manner that the carbon black is 0.02 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin particles, to obtain a mixed powder (P2). And a powder composition capable of obtaining a three-dimensional shaped object at high speed and high precision and a manufacturing method thereof can be provided.

Description

Technical Field

[0001] This invention relates to a method for manufacturing three-dimensional models with high speed and high precision suitable for a wide range of applications such as automobiles, aerospace, industry, and medicine, and further, a powder composition suitable for use as the material and a method for manufacturing the same. Background Technology

[0002] Three-dimensional modeling, due to its ability to allow for a high degree of freedom in shape design, is widely used in automotive, aerospace, industrial, and medical applications. Powder additive manufacturing is preferred for this type of modeling due to its ability to achieve good mechanical strength and its elimination of the need for supporting components. In recent years, with advancements in application development, research has been conducted on functional prototyping to confirm the performance of the designed shapes and on the final product applications of the three-dimensional models. This has led to increasingly higher demands for high-speed manufacturing processes and high-precision three-dimensional models.

[0003] In powder additive manufacturing, the powder bed fusion bonding method is a manufacturing method that involves repeatedly performing the following steps: spreading resin particles into a thin layer to form a thin layer, and irradiating the formed thin layer with a laser to form a cross-sectional shape corresponding to the cross-sectional shape of the object being modeled, so that the powder is bonded to form a cross-sectional shape. This modeling method has excellent modeling accuracy.

[0004] In manufacturing three-dimensional objects using a powder bed fusion bonding method, it is known to use thermoplastic resin powder compositions containing carbon black. For example, Patent Document 1 discloses a method for improving molding accuracy by adding carbon black to thermoplastic resin particles to reduce the electromagnetic reflectivity of the three-dimensional object to below 10%. Patent Document 2 discloses a polyarylketone powder containing carbon black as both a flame retardant and a laser absorber. Furthermore, it is known to use lasers with wavelengths of 400–2000 nm, such as fiber lasers, in powder bed fusion bonding methods using resin particles to accelerate the manufacturing process.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-162846

[0008] Patent Document 2: Japanese Patent Application Publication No. 2007-39631 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The objective of this invention is to provide a powder composition capable of producing three-dimensional models with high speed and high precision, and a method for manufacturing the same. In particular, the objective of this invention is to provide a method and a three-dimensional model that produces a high-precision model free of color unevenness and spots in a powder bed fusion bonding method using a laser with a beam wavelength of 400-2000 nm generated by a fiber laser or similar device, which enables high-speed manufacturing processes.

[0011] Problem-solving methods

[0012] To address this issue, the present invention underwent in-depth research, resulting in the following invention. That is, the present invention is as follows.

[0013] <1> A method for manufacturing a powder composition, said powder composition being a powder additive manufacturing method, said manufacturing method comprising the following steps (a) to (b):

[0014] (a) In step 100 parts by weight of thermoplastic resin particles, 0.2 to 50 parts by weight of carbon black with an absorption capacity of DBP (dibutyl phthalate) of 10 ml / 100 g or more and 500 ml / 100 g or less are mixed to obtain a premixed powder (P1).

[0015] (b) In the process of adding mixed thermoplastic resin particles to the premixed powder (P1) in such a way that the amount of carbon black is 0.02 to 5 parts by weight relative to 100 parts by weight of thermoplastic resin particles, a mixed powder (P2) is obtained.

[0016] <2> .like <1> The method for manufacturing the powder composition further includes step (c).

[0017] (c) Step, in which the premixed powder (P1) or mixed powder (P2) is passed through a filter with an opening of 100 μm or more and 500 μm or less.

[0018] <3> .like <1> or <2> The method for manufacturing the powder composition, wherein step (a) and / or step (b) comprises mixing by applying shear force using a stirring blade.

[0019] <4> A powder composition for use in powder additive manufacturing, comprising, relative to 100 parts by weight of thermoplastic resin particles, 0.02 to 5 parts by weight of carbon black with a DBP absorption of 10 ml / 100 g or more and 500 ml / 100 g or less, wherein the average particle size of the powder composition is 1 μm or more and 100 μm or less, and 9500 cm⁻¹ -1 The transmittance of near-infrared light is less than 75%.

[0020] <5> .like <4> The powder composition wherein coarse particles with a particle size of 250 μm or more account for less than 0.1% by weight.

[0021] <6> .like <4> or <5> The powder composition wherein the thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylethermon sulfide, polyamide, polybutylene terephthalate and polyetheretherketone.

[0022] <7> .like <4> ~ <6> The powder composition according to any one of the following methods, wherein the average particle size of the carbon black is 100 nm to 1000 nm.

[0023] <8> .like <4> ~ <7> The powder composition according to any one of the following methods, wherein, relative to 100 parts by weight of the thermoplastic resin particles, contains 1 to 100 parts by weight of inorganic reinforcing material.

[0024] <9> .like <8> The inorganic reinforcing material in the powder composition is at least one selected from glass fiber, glass beads, and carbon fiber.

[0025] <10> .like <4> ~ <9> The powder composition described in any one of the above statements, wherein the powder additive manufacturing method is a powder bed fusion bonding method using a laser with a beam wavelength of 400nm to 2000nm.

[0026] <11> .like <10> The powder composition wherein the laser beam with a wavelength of 400nm to 2000nm is generated by a fiber laser.

[0027] <12> A method for manufacturing a three-dimensional object, wherein, using <1> ~ <3> The powder composition is manufactured by any one of the methods described above, and then a three-dimensional model is manufactured by powder additive manufacturing.

[0028] <13> A method for manufacturing a three-dimensional model, wherein, for <4> ~ <11> The powder composition described in any one of the above methods is irradiated with a laser beam with a wavelength of 400nm to 2000nm to manufacture a three-dimensional model through a powder bed fusion bonding method.

[0029] <14> A three-dimensional object, obtained by powder additive manufacturing, wherein spots with a diameter of 150 μm or larger are observed on the surface of the three-dimensional object at a density of 100 cm². 2 The surface area of ​​a three-dimensional object is less than 2.

[0030] <15> A three-dimensional object obtained by powder additive manufacturing using a powder composition, wherein the powder composition is... <4> ~ <11> When using any one of the powder compositions to fabricate 12 test pieces with a width of 10 mm, a length of 80 mm, and a thickness of 4.0 mm by powder additive manufacturing, the number of spots with a diameter of 150 μm or more observed on the 10 mm × 80 mm surface side plane is 2 or less per 12 test pieces.

[0031] The test piece was prepared with the length of 80 mm in the X direction (the direction of recoater movement), the width of 10 mm in the Y direction (the direction orthogonal to the recoater's movement on the plane of recoater movement), and the thickness of 4.0 mm in the Z direction (the direction perpendicular to the recoater's movement).

[0032] <16> .like <15> The aforementioned three-dimensional model is a three-dimensional model used for automotive parts, aerospace parts, or robotic parts.

[0033] Invention Effects

[0034] According to the present invention, a powder composition capable of producing three-dimensional shapes with high speed and high precision, and a method for manufacturing the same, can be provided. In particular, in a powder bed fusion bonding method that enables high-speed manufacturing and uses a laser with a beam wavelength of 400 to 2000 nm, such as a fiber laser, it is possible to obtain shapes with high precision and no color unevenness or spots. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the embodiments.

[0036] To obtain three-dimensional models with high speed and precision, excellent energy absorption and processability are crucial in powder additive manufacturing. This invention reveals that a powder composition containing 0.02 to 5 parts by weight of DBP and carbon black with an absorption capacity of 10 ml / 100g or more and 500 ml / 100g or less, relative to 100 parts by weight of thermoplastic resin particles, achieves a high energy absorption capacity at 9500 cm⁻¹. -1 It has excellent absorption of near-infrared light (low transmittance), and based on this property, it is suitable for powder bed fusion bonding molding using lasers with beam wavelengths of 400nm to 2000nm.

[0037] Furthermore, the present invention relates to a method for manufacturing a powder composition used in powder additive manufacturing, characterized by comprising the following steps (a) and (b).

[0038] (a) Process: 0.2 to 50 parts by weight of carbon black with an absorption capacity of 10 ml / 100g or more and 500 ml / 100g or less of DBP (dibutyl phthalate) relative to 100 parts by weight of thermoplastic resin particles are mixed to obtain a premixed powder (P1).

[0039] (b) Process: Thermoplastic resin particles are added to the premixed powder (P1) in such a way that the carbon black is 0.02 to 5 parts by weight relative to 100 parts by weight of thermoplastic resin particles to obtain a mixed powder (P2).

[0040] It was found that by performing the above-described steps (a) and (b), the resulting three-dimensional modeled object obtained by using the powder composition for three-dimensional modeling has no uneven color or spots, and becomes a modeled object with good precision, thus completing the present invention.

[0041] As for the carbon black used in this invention, any carbon black that does not impair the properties of the powder composition is acceptable, and there is no particular limitation on its type. Carbon black with excellent absorption properties for laser beams with wavelengths of 400 to 2000 nm is particularly preferred. Specifically, furnace black, channel black, acetylene black, thermal black, and Ketjen black can be listed. From the viewpoint of high specific surface area and the ability to exert effects with a smaller amount, furnace black and acetylene black are preferred. From the viewpoint of not easily impairing the properties of the powder composition, furnace black is the most preferred.

[0042] The carbon black used in this invention can reduce the amount of gas generated during laser irradiation; therefore, neutral carbon black is preferred. Alternatively, preheating and drying acidic carbon black before use can further reduce gas generation.

[0043] DBP (dibutyl phthalate) absorption is an indicator of the amount of DBP absorbed on the surface of carbon black particles and in the voids formed by aggregated particles, i.e., oil absorption, and can be measured according to JIS K 6217-4:2008. In this invention, the DBP absorption is 10 ml / 100g or more and 500 ml / 100g or less. If the DBP absorption is less than 10 ml / 100g, the coating of carbon black on the surface of thermoplastic resin particles becomes uneven, the laser energy cannot reach the entire surface, and uniform sintering of the thermoplastic resin particles cannot be achieved. More preferably, it is 15 ml / 100g or more, further preferably 20 ml / 100g or more, and particularly preferably 25 ml / 100g or more. Furthermore, if it is 500 ml / 100g or more, the specific surface area of ​​the carbon black increases, the carbon black easily aggregates, and a uniform three-dimensional shape cannot be obtained. More preferably, it is 400ml / 100g or less, even more preferably 300ml / 100g or less, and particularly preferably 200ml / 100g or less.

[0044] The average particle size of the carbon black of the present invention is preferably 10 to 1000 nm, and particularly preferably 100 to 1000 nm. With a particle size of 100 nm or more, the carbon black can be uniformly dispersed as primary particles in the powder composition, and it is difficult to agglomerate during molding, thus stably obtaining three-dimensional molded objects. Furthermore, by making the average particle size 1000 nm or less, sufficient energy absorption can be achieved with a relatively small amount added.

[0045] Carbon black that has been pre-crushed and dispersed can also be used. The crushing and dispersion of carbon black can be achieved using known methods, such as mechanical crushing and dispersion methods like high-speed mixers and ball mills, air jet milling methods like air jet mills, electrostatic treatment, and electromagnetic field treatment. It can also be passed through a suitable open sieve to remove coarse particles and agglomerates. Mechanical crushing and dispersion using a high-speed mixer is particularly preferred. Mechanical crushing using a high-speed mixer results in excellent homogeneity in the powder composition and excellent dispersion stability during reuse in molding, making it well-suited for three-dimensional molding using lasers with beam wavelengths of 400–2000 nm, yielding three-dimensional models with excellent quality and mechanical properties.

[0046] In this invention, the carbon black comprises 0.02 to 5 parts by weight when the resin particles are set to 100 parts by weight. If it is less than 0.02 parts by weight, energy cannot be absorbed, and the resin cannot be sufficiently sintered. Preferably, it is 0.03 parts by weight or more, more preferably 0.05 parts by weight or more, even more preferably 0.08 parts by weight or more, and particularly preferably 0.1 parts by weight or more. Furthermore, if it exceeds 5 parts by weight, the adhesion between the resin particles weakens, and the strength of the three-dimensional model decreases. Preferably, it is 3 parts by weight or less, more preferably 2 parts by weight or less, even more preferably 1 part by weight or less, and particularly preferably 0.5 parts by weight or less.

[0047] The thermoplastic resin used in this invention is preferably a thermoplastic resin due to its excellent flowability during melting. Examples of such thermoplastic resins include polyarylene sulfide resins, particularly polyphenylene sulfide resin (PPS), polyamide resins, particularly various nylons such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, and nylon 46, polyesters such as polybutylene terephthalate (PBT), polycarbonate resin (PC), polyimide resin, polyetherimide resin, polyetherketone ketone resin, polyetheretherketone resin, polymethyl methacrylate, polytetrafluoroethylene resin, polyvinylidene fluoride resin, polyvinyl acetate, polyacetal, polysulfone resin, polystyrene resin, polylactic acid, polycaprolactone, methyl acrylate-methyl methacrylate copolymer, acrylonitrile-styrene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene resin-acrylic acid copolymer, ethylene-propylene copolymer, and ABS (acrylonitrile-butadiene-styrene copolymer). Furthermore, the thermoplastic resin in this invention can be any of random copolymers, block copolymers, and combinations thereof. From the viewpoint of mechanical strength and heat resistance, at least one of polyarylene sulfide resin, polyamide resin, polybutylene terephthalate resin, polypropylene resin, and polyetherketone ketone resin is preferred; from the viewpoint of low water absorption and excellent dielectric properties, polyarylene sulfide resin is particularly preferred.

[0048] The melt viscosity of the thermoplastic resin used in this invention is preferably 150 Pa·s or higher and 500 Pa·s or lower. If the melt viscosity is lower than 150 Pa·s, the strength of the three-dimensional model will be lower. If the melt viscosity is higher than 500 Pa·s, when the resin is melted by laser irradiation, the molten resin cannot penetrate to the lower layer, so the interlayer bonding will be weaker, and the strength of the model in the height direction may be significantly reduced.

[0049] Here, the melt viscosity was determined using a Toyo Seiki capillary rheometer 1C with a mold having an orifice length of 10.00 mm and an orifice diameter of 0.50 mm. Melt viscosity was determined by placing approximately 20 g of sample into a barrel at a temperature set 20°C higher than the melting point of the thermoplastic resin, holding it for 5 minutes, and then measuring the melt viscosity at a shear rate of 1216 sec. -1 The value is obtained by measuring the melt viscosity. The preferred lower limit of the melt viscosity is 150 Pa·s, more preferably 160 Pa·s, even more preferably 170 Pa·s, and particularly preferably 180 Pa·s. The preferred upper limit of the melt viscosity is 500 Pa·s, more preferably 450 Pa·s, even more preferably 400 Pa·s, and particularly preferably 350 Pa·s.

[0050] Furthermore, the difference between the melting point and recrystallization temperature of the thermoplastic resin used in this invention is preferably 30°C or higher. If the difference between the melting point and recrystallization temperature of the thermoplastic resin is less than 30°C, the resin melted by laser irradiation may shrink or warp during crystallization. If the resin warps during the powder bed fusion bonding method, the molten resin may be dragged when the powder layer is stacked on top of the molten resin, and the desired three-dimensional shape cannot be obtained.

[0051] Here, recrystallization temperature refers to the peak temperature of the exothermic peak during crystallization, achieved by using a differential scanning calorimeter to heat the thermoplastic resin in a nitrogen atmosphere from 50°C to a temperature 40°C above its melting point at a rate of 20°C / min, holding the temperature for 5 minutes, and then cooling it back to 50°C at a rate of 20°C / min. In cases with multiple peaks, the peak at the highest temperature is taken as both the melting point and the crystallization temperature.

[0052] The average particle size of the thermoplastic resin particles of the present invention is preferably greater than 1 μm and less than 100 μm. A more preferred lower limit for the average particle size is 3 μm, more preferably 5 μm, particularly preferably 8 μm, especially preferably 10 μm, and most preferably 15 μm. Furthermore, a more preferred upper limit for the average particle size is 90 μm, further preferably 85 μm, particularly preferably 80 μm, especially preferably 75 μm, and most preferably 70 μm. When the average particle size exceeds 100 μm, uniformity is compromised during powder stacking in a powder bed fusion 3D printer, resulting in reduced strength of the three-dimensional model. On the other hand, when the average particle size is less than 1 μm, the agglomeration of resin particles due to electrostatic generation also compromises uniformity during powder stacking, leading to reduced strength of the three-dimensional model.

[0053] In this invention, the sphericity, which represents the sphericity of thermoplastic resin particles, is not particularly specified. However, from the viewpoint of good formability of powder additive manufacturing and excellent surface smoothness of the obtained three-dimensional model, the sphericity is preferably 0.8 or more and 1 or less. More preferably, the sphericity is 0.85 or more and 1 or less, and even more preferably, 0.9 or more and 1 or less.

[0054] In addition, the sphericity of the thermoplastic resin particles in this invention is determined by randomly observing 30 particles from a scanning electron microscope photograph and based on the ratio of their minor axis to major axis.

[0055] In the manufacture of the thermoplastic resin particles of the present invention, there are no particular limitations. Particles obtained through polymerization can be used as thermoplastic resin particles, or particles can be obtained by molding resin into particles, fibers, films, etc. Furthermore, the crushing and dispersion process described later can be performed depending on the morphology of the resin particles used. Other methods include spray drying after dissolving the raw materials in a solvent, solvent precipitation after forming an emulsion in a solvent and then contacting it with a poor solvent, liquid drying after forming an emulsion in a solvent and then drying away the organic solvent, and forced melt mixing to form an island structure by mechanically mixing the resin component to be granulated with a different resin component, and then removing the island component with a solvent. From an economic point of view, crushing and dispersion is preferred. There are no particular limitations on the crushing and dispersion method; examples include disc mills, air jet mills, bead mills, hammer mills, ball mills, sand mills, turbine mills, and cryogenic mills. Dry milling methods such as turbine mills, air jet mills, and cryogenic mills are preferred, and cryogenic milling is even more preferred.

[0056] In this invention, the powder composition may be a powder mixture of thermoplastic resin particles and carbon black, or carbon black may be encapsulated within thermoplastic resin particles. However, from the viewpoint of easy energy absorption and facilitating the melting and sintering between thermoplastic resin particles, a powder mixture is preferred.

[0057] Carbon black-encapsulated particles can be obtained by the following methods: solvent precipitation method, which involves dissolving a mixture of pre-mixed thermoplastic resin and carbon black, forming an emulsion in a solvent, and then contacting it with a poor solvent; liquid drying method, which involves forming an emulsion in a solvent and then drying to remove the organic solvent; forced melt mixing method, which involves mechanically mixing the resin component to be granulated with a different resin component to form an island structure and then removing the island component with a solvent; and pulverizing the carbon black after melt mixing in a polymer.

[0058] In the case of powder mixtures, the mixing of thermoplastic resin particles and carbon black is preferably carried out by rotating the rotating blades mounted on a container rotary mixer. This allows for the simultaneous breaking up and dispersing of carbon black agglomerates while uniformly mixing. Other methods include mixing with pulverization such as ball mills or coffee grinders; mixing with stirring blades such as Notta mixers or Henschel mixers; mixing by rotating the container such as V-type mixers; drying after liquid-phase mixing in a solvent; mixing with airflow such as flash mixers; and mixing powders and / or slurries by spraying using an atomizer.

[0059] The method for manufacturing the powder composition of the present invention is characterized by comprising: a step (a) of mixing 0.2 to 50 parts by weight of carbon black relative to 100 parts by weight of thermoplastic resin particles to obtain a premixed powder (P1); and a step (b) of adding thermoplastic resin particles to the premixed powder (P1) in such a way that the carbon black is 0.02 to 5 parts by weight relative to 100 parts by weight of thermoplastic resin particles to obtain a mixed powder (P2). By pre-manufacturing the premixed powder (P1) as a masterbatch, the agglomeration of carbon black can be suppressed, and by using the premixed powder (P1) as a raw material to obtain the mixed powder (P2), a powder composition suitable for use in three-dimensional molding with uniform carbon black dispersion can be obtained.

[0060] In the method for manufacturing the powder composition of the present invention, the amount of carbon black is 0.2 to 50 parts by weight relative to 100 parts by weight of thermoplastic resin particles in step (a) of obtaining the premixed powder (P1). If it is less than 0.2 parts by weight, the amount of thermoplastic resin particles relative to carbon black will be relatively large in the masterbatch manufacturing process, resulting in localized enrichment of carbon black and making it difficult to disperse. Preferably, it is 0.3 parts by weight or more, more preferably 0.5 parts by weight or more, further preferably 1 part by weight or more, and particularly preferably 3 parts by weight or more. In addition, if it exceeds 50 parts by weight, the carbon black becomes highly concentrated, which may cause secondary agglomeration of carbon black. Preferably, it is 40 parts by weight or less, more preferably 30 parts by weight or less, further preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less.

[0061] In step (a) to obtain the premixed powder (P1), it is preferable to mix until there is no visual discoloration or unevenness. By making the premixed powder (P1) as homogeneous as possible, a homogeneous mixed powder (P2) can be obtained in step (b).

[0062] In the method for manufacturing the powder composition of the present invention, it is preferable to further include a step (c) of passing the premixed powder (P1) or the mixed powder (P2) through a filter with an opening size of 100 μm or more and 500 μm or less. Filtering the premixed powder (P1) can also disperse the carbon black, resulting in a more homogeneous masterbatch. Furthermore, if the mixed powder (P2) is filtered, the thermoplastic resin particles can be sieved as a whole, and coarse particles can be physically removed, thus suppressing the formation of coarse black powder coated with carbon black. Therefore, it is more preferable to pass both the premixed powder (P1) and the mixed powder (P2) through the filter.

[0063] The filter openings preferably used in step (c) of the method for manufacturing the powder composition of the present invention, if having a lower limit of 100 μm or more, can selectively remove only coarse particles without removing thermoplastic resin particles of a particle size suitable for three-dimensional molding. Therefore, 115 μm or more is more preferred, 130 μm or more is even more preferred, and 145 μm or more is particularly preferred. If the upper limit is 500 μm or less, coarse particles that would be a defect in three-dimensional molded objects can be removed. 400 μm or less is more preferred, 350 μm or less is even more preferred, and 300 μm or less is particularly preferred.

[0064] In the method for manufacturing the powder composition of the present invention, steps (a) and / or (b) preferably include mixing using the shear force of a stirring blade. Carbon black is prone to agglomeration during mixing due to friction or static electricity, sometimes resulting in uneven mixing with the thermoplastic resin particles. To solve this problem, by including the shear force of a stirring blade during mixing, the agglomeration of carbon black can be broken up while mixing, resulting in a more uniform mixture. It is preferable that one or more stirring blades are mounted relative to a container. The rotational speed of the container in the rotary mixer for mixing thermoplastic resin particles and carbon black is preferably 3.5 rpm to 35 rpm, more preferably 15 rpm to 30 rpm. The rotational speed of the stirring blades is preferably 100 rpm to 1000 rpm, more preferably 400 rpm to 700 rpm.

[0065] When inorganic reinforcement is included, it is preferable to perform the mixing in two stages. Preferably, the carbon black is mixed with the thermoplastic resin particles in the first stage, and then the mixture from the first stage is mixed with the inorganic reinforcement in the second stage. If the inorganic reinforcement and carbon black are mixed simultaneously, the surface of the inorganic reinforcement is also coated with carbon black, and the surface of the resin particles cannot be adequately coated. By mixing the carbon black and thermoplastic particles first, the carbon black can be coated on the particle surface, allowing the resin particles to fully absorb the energy of the irradiated laser.

[0066] The powder composition of the present invention has an average particle size of 1 μm or more and 100 μm or less. The preferred lower limit for the average particle size is 3 μm, more preferably 5 μm, further preferably 8 μm, particularly preferably 10 μm, and most preferably 15 μm. Furthermore, the preferred upper limit for the average particle size is 90 μm, more preferably 85 μm, further preferably 80 μm, particularly preferably 75 μm, and most preferably 70 μm. When the average particle size of the powder composition exceeds 100 μm, the uniformity of the powder during powder stacking in powder additive manufacturing is impaired, and the strength of the three-dimensional model decreases. On the other hand, when the average particle size is less than 1 μm, the powder composition agglomerates due to electrostatic generation, which also impairs the uniformity during powder stacking and reduces the strength of the three-dimensional model.

[0067] In the powder composition of the present invention, the weight of coarse particles with a particle size of 250 μm or more is preferably 0.1% by weight or less. When it exceeds 0.1% by weight, three-dimensional shapes manufactured from this powder composition by powder additive manufacturing will have color unevenness and spots due to the coarse particles. From the viewpoint of suppressing color unevenness and spots on three-dimensional shapes, it is preferable to have 0.05% by weight or less, more preferably 0.03% by weight or less, further preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less.

[0068] Coarse particles with a particle size of 250 μm or larger refer to coarse particles that are captured by a sieve when the powder composition passes through a sieve with an aperture of 250 μm as specified in JIS Z8801-1 (2006). These coarse particles can be composed solely of carbon black, or they can be composed of carbon black and other components contained in the powder composition. In addition, coarse particles composed solely of components other than carbon black may also be present.

[0069] The weight of coarse particles with a particle size of 250 μm or larger can be determined by passing the powder composition through a sieve with an aperture of 250 μm and weighing it based on the weight difference before and after passing through the sieve. Specifically, 2 kg of the powder composition is added to a sieve with an aperture of 250 μm as specified in Japanese Industrial Standard (JIS) JIS Z8801-1 (2006), and the sieve is vibrated until no more powder composition passes through the sieve. The weight difference before and after passing through the sieve is then defined as coarse particles with a particle size of 250 μm or larger. When weighing coarse particles, to prevent the weighing value from changing due to different methods of passing through the sieve, it is preferable to let the sieve stand still or pass it through with slight vibration at room temperature (approximately 20–25°C), atmospheric pressure, and standard relative humidity (approximately 40–60%). Therefore, coarse particles cannot be weighed using any of the following methods that intentionally disperse coarse particles: physical treatment such as crushing, rubbing, or dispersing the powder composition on a sieve; treatment performed simultaneously with heating or cooling; treatment in a solvent; ultrasonic treatment; addition of surfactants; pH adjustment; electrophoresis; electroosmosis; magnetic treatment; etc.

[0070] In this invention, carbon black is uniformly dispersed in the powder composition, which is preferred for powder bed fusion bonding using lasers. The deviation of the L-value can be used as an indicator of this uniform dispersion. The deviation of the L-value is preferably 0.018 or less, more preferably 0.015 or less. When the deviation of the L-value exceeds 0.018, the carbon black is unevenly distributed on the resin surface, and the laser energy cannot reach all resin particles, reducing the accuracy of the three-dimensional model. The closer the L-value deviation is to 0, the more uniformly the carbon black is dispersed in the powder composition, indicating a homogeneous state. The deviation of the L-value is calculated by randomly collecting three samples from the powder composition, measuring the L-value, and dividing the standard deviation of the L-value by the average of the three L-values. The L-value can be measured using a spectrophotometer.

[0071] After mixing thermoplastic resin particles and carbon black using the above method, inorganic reinforcing materials can be incorporated into the resulting mixture. Mixing can be performed using methods such as a Notta mixer or Henschel mixer that utilizes stirring blades, a V-type mixer, or a cross-rotary mixer that rotates the container along with the mixture. However, to prevent damage to the inorganic reinforcing materials, a container-type rotary mixer is preferred. The preferred rotation speed of the container is 3.5 rpm to 35 rpm.

[0072] In this invention, the L value of the powder composition is preferably 80 or less. By having a low L value, the suppression effect on discoloration during the thermal process of the powder composition is improved. Furthermore, by having a low L value, laser absorption is easier during powder bed fusion molding, allowing for effective laser sintering of the powder composition. Theoretically, the lower limit of the L value of the powder composition is 0; the L value of the powder composition of this invention typically represents a value of 10 or more.

[0073] In this invention, the powder composition used in powder bed fusion molding with a laser beam wavelength of 400 nm to 2000 nm can be measured using a diffuse reflectance method at a density of 9500 cm⁻¹. -1 The near-infrared transmittance is used to evaluate the shapeability of the powder composition. In the diffuse reflectance method, since the transmittance spectrum is obtained by comparing the transmittance at a specific wavelength through the ortho-reflected light reflected from the surface of the powder composition and the diffuse reflected light transmitted through the interior of the powder composition, its absorbance can be evaluated. The powder composition of the present invention uses the diffuse reflectance method to measure the transmittance at 9500 cm⁻¹. -1 The transmittance of near-infrared light is 75% or less. By having a transmittance of 75% or less, the shapeability of laser beams with wavelengths from 400 nm to 2000 nm can be improved. Preferably, it is 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less.

[0074] In addition, the 9500 cm⁻¹ of the powder composition was measured using the diffuse reflectance method. -1The transmittance of near-infrared light can be evaluated, for example, by setting a diffuse reflectance measurement device (DRS-8000) on a Fourier transform infrared spectrophotometer (IRPRestige-21) manufactured by Shimadzu Corporation, with a tungsten lamp as the light source, calcium fluoride as the beam splitter, and InGaAs (indium gallium arsenide) as the detector. After filling the sample cell with potassium bromide to perform a blank measurement of near-infrared light, a powder composition sample is filled into the sample cell for near-infrared measurement.

[0075] Additives may be added as long as they do not impair the properties of the powder composition of the present invention. Examples of additives include heat stabilizers, antioxidants, flame retardants, plasticizers, flow aids, etc., which may be present either inside or outside the thermoplastic resin particles.

[0076] Regarding the shape of the inorganic reinforcing material in this invention, in order to improve the mechanical properties of the three-dimensional model, spherical, needle-like, plate-like, fibrous, etc. are preferred.

[0077] In this invention, there are no particular limitations on the inorganic reinforcing material added to the powder composition, and inorganic reinforcing materials with a maximum size of 1 μm or more and 400 μm or less can be used. To further enhance the mechanical properties of the three-dimensional model, a size of 20 μm or more is more preferred, and even more preferably 50 μm or more. Furthermore, from the viewpoint that larger sizes worsen the flowability of the powder composition, the maximum size of the powder composition is preferably 200 μm or less, and more preferably 170 μm or less. Here, the maximum size refers to the average value of the maximum length measured by observing the inorganic reinforcing material using a scanning electron microscope, randomly selecting any 100 inorganic reinforcing materials from an image magnified 100 times, and measuring the maximum distance between two points on the outer contour line of each inorganic reinforcing material.

[0078] Furthermore, the upper limit of the maximum size of the inorganic reinforcement is preferably 400 μm, more preferably 390 μm, more preferably 380 μm, and particularly preferably 370 μm. The lower limit is preferably 1 μm, more preferably 5 μm, further preferably 10 μm, and particularly preferably 15 μm. If the maximum size of the inorganic reinforcement is 400 μm or less, the flowability of the powder composition will not be impaired, and a uniform powder surface can be formed during powder stacking in a powder bed fusion 3D printer. Furthermore, if the maximum size of the inorganic reinforcement is 1 μm or more, an increase in the strength of the three-dimensional model made using the powder composition can be obtained.

[0079] When the inorganic reinforcement is fibrous, the fiber length is the longest dimension, and the average value of the longest dimension is the average value of the fiber length. Furthermore, the fiber diameter is preferably 0.1 μm or more and 50 μm or less. The preferred lower limit for the fiber diameter is 0.1 μm, more preferably 0.5 μm, and particularly preferably 1 μm. Additionally, the preferred upper limit for the fiber diameter is 5 μm, more preferably 40 μm, and particularly preferably 30 μm.

[0080] Examples of inorganic reinforcing materials used in this invention include talc, silica-containing compounds, minerals, glass fibers, glass beads, glass sheets, foamed glass beads, single-crystal potassium titanate, carbon fibers, carbon nanotubes, anthracite powder, titanium dioxide, magnesium oxide, potassium titanate, mica, asbestos, calcium sulfite, calcium silicate, molybdenum sulfide, boron fibers, and silicon carbide fibers. More preferably, glass beads, glass fibers, and carbon fibers are also included.

[0081] Relative to 100 parts by weight of thermoplastic resin particles, the amount of inorganic reinforcing material in the present invention is preferably 1 to 100 parts by weight, more preferably 10 to 100 parts by weight. A higher proportion of reinforcing material improves the strength of the molded object. By keeping the amount of inorganic reinforcing material to 100 parts by weight or less, the reduction in powder flowability during three-dimensional molding can be suppressed, therefore this is preferred.

[0082] By molding the powder composition of the present invention using a powder additive manufacturing method, a three-dimensional model of the present invention can be obtained. The three-dimensional model of the present invention will be described below.

[0083] In the powder composition of this invention, the carbon black is present on the outer surface of the thermoplastic resin powder. However, due to the laser irradiation during molding, the thermoplastic resin powder melts, so the carbon black remains in a powder state inside the thermoplastic resin powder or is encapsulated within it in a molten state. Therefore, the carbon black is retained in the three-dimensional model, preventing it from fading.

[0084] The carbon black content in the three-dimensional model of the present invention is 0.02% by weight or more and 5% by weight or less. If the carbon black is uniformly mixed in the powder composition, the weight of carbon black contained in the powder composition is the same as the weight of carbon black contained in the three-dimensional model manufactured by the powder composition using three-dimensional molding.

[0085] The carbon black content in three-dimensional molded objects can be quantified, for example, using thermogravimetric analysis (TGA). Specifically, a small piece of the three-dimensional molded object is placed as a sample in the sample pan of a TGA apparatus. The sample is heated at a controlled rate until the thermoplastic resin undergoes thermal decomposition and volatilization. The carbon black content can be quantified based on the weight change of the sample. If TGA is not feasible, high-performance liquid chromatography (HPLC) can be used for quantification. A sample is prepared by dissolving the small piece of the three-dimensional molded object in a suitable solvent. An appropriate column and mobile phase are set up in the HPLC apparatus. After injecting the sample solution, the carbon black is separated within the column, and the peak area is measured using a detector. Furthermore, a carbon black standard solution of known concentration is prepared, and a standard curve is constructed based on the peak areas of the standard samples. Finally, the carbon black content can be calculated by converting the peak areas of the samples to carbon black concentration using the standard curve.

[0086] Furthermore, since the carbon black is uniformly present on the surface of the thermoplastic resin powder and there are almost no aggregates containing carbon black with a particle size of 250 μm or larger, the powder composition of the present invention melts uniformly when melted by laser irradiation, thus obtaining a three-dimensional model with almost no color unevenness and spots.

[0087] The three-dimensional model of the present invention is characterized by spots with a diameter of 150 μm or more observed on the surface of the three-dimensional model, and the number of spots per 100 cm of the three-dimensional model. 2 The surface area is less than 100 cm². The surface area of ​​a three-dimensional object can be measured using known methods, such as scanning the object with a 3D scanner to generate 3D CAD data and then calculating the surface area using software. 2 In this case, multiple three-dimensional shapes are combined to form a 100cm shape. 2 The above surface area is used to evaluate the number of spots.

[0088] As a specific evaluation method for spots on 3D models, a powder bed fusion bonding method is used. Twelve test pieces are prepared with the following arrangement: an 80mm length direction aligned with the recoating device's movement direction (X-direction); a 10mm width direction perpendicular to the recoating device's movement direction (Y-direction); and a 4.0mm thickness direction perpendicular to the recoating device's movement plane. The number of test pieces with spots can then be evaluated. Preferably, there are no more than two spots with a diameter of 150μm or larger observed on a 10mm × 80mm surface plane out of every twelve test pieces. The presence of spots on the 3D model is visually confirmed, and the model is observed using an optical microscope. If the diameter is 150μm or larger, it is defined as a spot, and the average of the major and minor axes of the spot is taken as its diameter. Preferably, no spots with a diameter of 150μm or larger are observed on the 3D model.

[0089] Additionally, "surface plane" refers to the topmost plane in a 10mm × 80mm plane of the test piece. Furthermore, when creating a three-dimensional model by fusing powder compositions through a powder bed, the dimensions set in the template may differ from the actual dimensions of the resulting three-dimensional model due to crystallization shrinkage. Therefore, the surface area calculated based on the set values ​​is used for evaluation.

[0090] Furthermore, in this invention, a three-dimensional object with uneven color refers to a three-dimensional object with mottled texture and gradient color differences obtained by using a powder composition in which carbon black is not uniformly dispersed. A three-dimensional object with spots refers to a three-dimensional object in which different colors can be visually confirmed by using a powder composition containing "coarse particles with a particle size of 250 μm or more containing carbon black" for three-dimensional modeling.

[0091] The three-dimensional models of this invention are applicable to automotive parts, aerospace parts, robotic parts, medical device parts, auxiliary consumable parts, building parts, and electrical and electronic equipment parts. In particular, the ability to obtain dense, high-mechanical-property, and high-heat-resistant three-dimensional models through powder bed fusion bonding makes them especially suitable for automotive parts, aerospace parts, and robotic parts.

[0092] Example

[0093] The present invention will be described in more detail below through examples and comparative examples, but the present invention is not limited to these examples. In addition, various measurement methods are as follows.

[0094] [Average particle size of the powder composition]

[0095] The average particle size of the powder composition was measured using a laser diffraction-scattering particle size distribution measuring apparatus (NTXS, MT3300EXII) with a 0.5% by weight aqueous solution of polyoxyethylene cumyl phenyl ether (trade name Nonar 912A, manufactured by Toho Chemical Co., Ltd.) as the dispersion medium. Specifically, the total volume of particles obtained by analyzing laser scattered light obtained by the Microtrac method was set as 100%, and a cumulative curve was obtained. The particle size (median particle size: d50) corresponding to the point where the cumulative curve reaches 50% from the small particle size side was taken as the average particle size.

[0096] Average particle size of carbon black

[0097] Regarding the average particle size of carbon black, the powder composition was observed at 10,000x magnification using a scanning electron microscope (JSM-IT700HR) manufactured by Nippon Egis Corporation. The arithmetic mean of the particle sizes of 100 randomly selected carbon black particles from the photograph was taken as the number-average particle size. Furthermore, energy-dispersive X-ray analysis was used to determine if the material was carbon black.

[0098] [DBP absorption]

[0099] The DBP absorption of carbon black was measured using an absorbance meter (S410E manufactured by Asahi Souken Co., Ltd.) in accordance with JISK6217-4:2008. The oil absorption of DBP per 100g was taken as the DBP absorption.

[0100] [The 9500 cm⁻¹ value of the powder composition was determined using the diffuse reflectance method] -1 [Near-infrared light transmittance]

[0101] A diffuse reflectance measurement device (DRS-8000) was set up on a Fourier transform infrared spectrophotometer (IRPrestige-21) manufactured by Shimadzu Corporation. A tungsten lamp was used as the light source, calcium fluoride was used as the beam splitter, and InGaAs (indium gallium arsenide) was used as the detector. After blank near-infrared light measurement with potassium bromide filled in the sample cell, a powder composition sample was filled in the sample cell for near-infrared measurement. The wavelength of 9500 cm⁻¹ was determined. -1 The transmittance of near-infrared light.

[0102] [Hue Measurement]

[0103] The L-value of the powder composition was measured using a spectrophotometer (SE2000) manufactured by Nippon Denshoku Kogyo Co., Ltd. Measurements were performed by tightly filling a dedicated colorless, transparent quartz petri dish while applying vibration. The deviation of the L-value was calculated by randomly selecting three samples from the powder composition, measuring the L-value, and dividing the standard deviation of the L-value by the average of the three L-values.

[0104] [Amount of coarse particles with a diameter of 250 μm or larger]

[0105] 2.0 kg of the powder composition was passed through a Test sieve (250 μm aperture) manufactured by Tokyo Screen Co., Ltd., as specified in Japanese Industrial Standard (JIS) Z8801-1 (2006). The weight difference of the sieve before and after passing through it was measured and expressed as a percentage by weight (wt%) of the amount of agglomerates relative to 100% by weight of the powder composition. The powder composition was passed through the sieve once.

[0106] Regarding color unevenness and spots on 3D models, a RaFaElII 150C-HT powder bed fusion 3D printer (Aspect Co., Ltd.) was used. Twelve test pieces were fabricated with a width of 10mm, a length of 80mm, and a thickness of 4.00mm, arranged such that the length of 80mm was aligned with the direction of recoating movement (X-direction), the width of 10mm was aligned with the direction of recoating movement (Y-direction) in the plane of recoating movement, and the thickness of 4.0mm was aligned with the plane of recoating movement. The number of 3D models with visually perceptible color unevenness was evaluated. Regarding spots on 3D models, a Keyence optical microscope (VHX-5000) and a Keyence objective lens VH-ZST (ZS-20) were used to evaluate the number of 3D models with spots larger than 50μm in diameter observed on a 10mm × 80mm surface plane.

[0107] [Determination of tensile strength of three-dimensional objects]

[0108] The tensile strength of the three-dimensional model was measured using a tensile test specimen (total length 170 mm, parallel length 80 mm, parallel width 10 mm, thickness 4 mm) prepared according to ISO 527-1A with the length direction of 170 mm as the X-direction. The X-direction tensile strength was determined using a TENSIRON TRG-1250 universal testing machine manufactured by A&D. Following JIS K7161 (2014), the tensile strength was determined under conditions of a gripping distance of 115 mm and a testing speed of 0.5 mm / min. The measurement temperature was room temperature (23℃), and the number of measurements (n = 10) was calculated, yielding the average value.

[0109] [Method for mixing powder compositions]

[0110] In the powder composition mixing method of this invention, resin particles and carbon black are mixed for 20 minutes under a nitrogen atmosphere and at room temperature and pressure using a cross-rotation mixer with a shredder mounted inside a container. During this time, the rotation speed of the shredder is 600 rpm. When mixing inorganic reinforcement, the inorganic reinforcement is added to the pre-mixed mixture of resin particles and carbon black, and mixed for 20 minutes under a nitrogen atmosphere and at room temperature and pressure using a cross-rotation mixer. During this time, mixing is performed without using a shredder.

[0111] [Manufacturing Example 1]

[0112] Add 1.00 mol of 47 wt% sodium hydrosulfide, 1.05 mol of 46 wt% sodium hydroxide, 1.65 mol of N-methyl-2-pyrrolidone (NMP), 0.45 mol of sodium acetate, and 5.55 mol of deionized water to a 1-liter high-pressure vessel equipped with a stirrer. While purging nitrogen gas at atmospheric pressure, slowly heat to 225°C for about 2 hours. Distill off 11.70 mol of water and 0.02 mol of NMP. Then cool the reaction vessel to 160°C.

[0113] Next, 1.02 mol of p-dichlorobenzene (p-DCB) and 1.32 mol of NMP were added. The reaction vessel was sealed under nitrogen atmosphere, and the mixture was stirred at 400 rpm while simultaneously undergoing a two-stage heating process: from 160°C to 240°C at a rate of 0.4°C / min, and then from 240°C to 270°C at a rate of 0.4°C / min. After reaching 270°C for 10 minutes, 0.75 mol of water was injected into the system over 15 minutes. After 120 minutes at 270°C, the mixture was cooled to 200°C at a rate of 1.0°C / min, and then rapidly cooled to near room temperature. The contents were then removed.

[0114] Remove the contents, dilute with 0.5 L NMP, filter through an 80 mesh sieve to separate the solvent and solids, wash the obtained solids several times with 1 L warm water, add 0.45 wt% calcium acetate 1-hydrate (800 g) relative to the solids for washing, wash again with 1 L warm water, filter to obtain filter cake.

[0115] The obtained filter cake was dried under a nitrogen stream at 120°C to obtain polyarylene sulfide resin. The polyarylene sulfide resin was pulverized to obtain an average particle size of 50 μm, an L value of 97, and a particle size of 9500 cm⁻¹ as determined by diffuse reflectance method of the powder composition. -1 Polyphenylene sulfide (PPS) resin particles with 100% near-infrared light transmittance.

[0116] [Manufacturing Example 2]

[0117] In a high-pressure reactor equipped with a 3L spiral-belt agitator, 300g of ε-caprolactam (manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd.), a monomer of polyamide, 700g of polyethylene glycol (grade 1 polyethylene glycol 20000, weight average molecular weight 18000, manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd.), a polymer incompatible with polyamide, and 1000g of water were added. After forming a homogeneous solution, the reactor was sealed and purged with nitrogen. Then, the stirring speed was set to 40 rpm, and the temperature was raised to 210°C. At this point, the pressure of the system reached 10 kg / cm³. 2 Then, while slowly releasing water vapor, the pressure is controlled to maintain at 10 kg / cm². 2 After the temperature reaches 210℃, at a rate of 0.2 kg / cm² 2 The pressure was released at a rate of minutes. Then, the temperature was maintained for 1 hour while nitrogen was introduced to complete the polymerization. While maintaining the polyethylene glycol in a molten state, the mixture of polyamide powder and polyethylene glycol was discharged into a 2000g water bath to obtain a slurry. After the slurry was thoroughly homogenized by stirring, it was filtered, and 2000g of water was added to the filter material for washing at 80°C. Then, the slurry, which had passed through a 100μm sieve to remove agglomerates, was filtered again, and the separated filter material was dried at 80°C for 12 hours to produce 170g of polyamide 6 powder. The obtained polyamide powder had a sphericity of 92, an average particle size of 51μm, and an L value of 97. A diffuse reflectance of 9500 cm⁻¹ was obtained using the diffuse reflectance method of the powder composition. -1 Polyamide 6 (PA6) particles with 100% near-infrared light transmittance.

[0118] [Example 1]

[0119] In a 1L plastic bag, 20g of AsahiCarbon#15 (manufactured by Asahi Carbon, furnace black, DBP absorbance 42ml / 100g, L-value 15, average particle size 122nm) was weighed into 250g of PPS resin particles obtained in Manufacturing Example 1. The mixture was hand-shaken until a colorless mixture was formed, and then homogenized by passing it through a 300μm sieve to obtain a premixed powder (P1). To 270g of this premixed powder (P1), 9.75kg of PPS resin particles were mixed, with 0.20 parts by weight of carbon black in the powder composition. The mixture was then mixed for 20 minutes in a cross-rotation mixer with a shredder mounted inside the container under nitrogen atmosphere, ambient temperature and pressure, to obtain a mixed powder (P2). The shredder rotated at 600rpm. This mixed powder (P2) was then passed through a vibrating screen with a 212μm sieve to produce a powder composition for three-dimensional modeling. At this point, the L value of the powder composition was 73, and the deviation of the L value was 0.009. Additionally, the L value of the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹.-1 The near-infrared light transmittance is 58%. The amount of coarse particles with a diameter of 250 μm or larger is 0.01 by weight.

[0120] Using 1.5 kg of the obtained powder composition, three-dimensional models were manufactured using a powder bed fusion bonding apparatus (RaFaElII 300C-HT) manufactured by Aspect Co., Ltd. The settings were: 60W CO2 laser, temperature set at 260°C, layer height 0.1 mm, laser scanning interval 0.1 mm, laser scanning speed 5 m / s, and laser output 18W. The resulting three-dimensional model had a good appearance and was not characterized by uneven coloring or spots. Furthermore, the tensile strength of the resulting three-dimensional model was 49 MPa. The obtained powder composition is suitable for powder bed fusion bonding using lasers with beam wavelengths from 400 nm to 2000 nm.

[0121] Using 10 kg of this powder composition, three-dimensional models were fabricated using a Farsoon powder bed fusion bonding apparatus (Flight ST252P). The settings were: a 300W fiber laser, a temperature of 258°C, a stack height of 0.1 mm, a laser scanning interval of 0.25 mm, a laser scanning speed of 20 m / s, and a laser output of 180 W. The resulting three-dimensional models exhibited good appearance, without uneven coloring or spots. Furthermore, the tensile strength of the resulting three-dimensional models was 54 MPa, demonstrating tensile strength equal to or exceeding that of models produced using a CO2 laser.

[0122] [Example 2]

[0123] The carbon black content relative to 250g of PPS resin particles was changed to 10g, resulting in a carbon black content of 0.13 parts by weight in the powder composition. The carbon black was mechanically crushed and dispersed using a high-speed mixer beforehand. A premixed powder (P1) was prepared using the same method as in Example 1, except for these steps. Then, 7.25kg of PPS resin particles were mixed, and a mixed powder (P2) was obtained using the same method as in Example 1. 2.5kg of glass fiber EPG70MD-01N (manufactured by Nippon Electric Glass Co., Ltd., fiber length 75μm) was further added as an inorganic reinforcing material to this mixed powder (P2), and the mixture was mixed for 20 minutes using a cross-rotation mixer under a nitrogen atmosphere at room temperature and pressure. During this process, mixing was performed without using a shredder. The resulting mixed powder was then passed through a vibrating screen with a sieve having a pore size of 212μm to produce a powder composition for three-dimensional modeling. The L value of the obtained powder composition was 66, with a deviation of 0.006. In addition, the 9500 cm⁻¹ of the powder composition was measured using the diffuse reflectance method. -1The near-infrared light transmittance is 40%. The amount of coarse particles with a diameter of 250 μm or larger is 0.02 by weight.

[0124] The obtained powder composition was subjected to three-dimensional modeling under the same methods and conditions as in Example 1. The resulting three-dimensional model had a good appearance and was not characterized by uneven coloring or spots. Furthermore, the tensile strength of the obtained three-dimensional model was 60 MPa. The obtained powder composition is suitable for modeling using a powder bed fusion bonding method with a laser beam wavelength of 400 nm to 2000 nm.

[0125] Using 10 kg of the powder composition, under the same conditions as in Example 1, three-dimensional modeling was performed using a Farsoon powder bed fusion bonding apparatus (Flight ST252P). The resulting three-dimensional model had a good appearance and was not characterized by uneven coloring or spots. Furthermore, the tensile strength of the obtained three-dimensional model was 62 MPa, exhibiting tensile strength equal to or greater than that of three-dimensional models using a CO2 laser.

[0126] [Example 3]

[0127] Except for using MA230 (manufactured by Mitsubishi Chemical Corporation, furnace black, DBP absorbance 113 ml / 100 g, L value 9, average particle size 30 nm) as the carbon black, a powder composition for three-dimensional modeling was prepared in the same manner as in Example 1. The L value of the powder composition was 63, and the deviation of the L value was 0.010. Furthermore, the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹. -1 The near-infrared light transmittance is 49%. The amount of coarse particles with a diameter of 250 μm or larger is 0.02% by weight.

[0128] The obtained powder composition was subjected to three-dimensional modeling using the same methods and conditions as in Example 1. The resulting three-dimensional models had a good appearance and were not characterized by uneven coloring or spots. The obtained powder composition is suitable for modeling using a powder bed fusion bonding method with a laser beam wavelength of 400 nm to 2000 nm.

[0129] [Example 4]

[0130] Polyamide 6 particles (average particle size 51 μm, L value of 97, 9500 cm⁻¹, obtained by pulverizing polyamide 6 resin) were used as thermoplastic resin particles. -1The near-infrared transmittance was 100%. In step (a) of obtaining the premixed powder (P1), the amount of carbon black added was changed to 10 g, and the carbon black in the powder composition was changed to 0.10 parts by weight. Except for these changes, the powder mixture was prepared in the same manner as in Example 1. The L value of the powder composition was 62, and the deviation of the L value was 0.008. Furthermore, the transmittance of the powder composition at 9500 cm⁻¹ was measured using the diffuse reflectance method. -1 The near-infrared light transmittance is 43%. The amount of coarse particles with a diameter of 250 μm or larger is 0.02 by weight.

[0131] The obtained powder composition was subjected to three-dimensional modeling under the same methods and conditions as in Example 1, except that the laser output was changed to 10W and the temperature was set to 202°C. The resulting three-dimensional model had a good appearance and was not a model with uneven color or spots. The obtained powder composition is suitable for modeling using a powder bed fusion bonding method with a laser beam wavelength of 400nm to 2000nm.

[0132] [Example 5]

[0133] Polyamide 6 particles obtained in Manufacturing Example 2 were used as thermoplastic resin particles. The amount of carbon black added in step (a) of obtaining the premixed powder (P1) was set to 10 g, so that the carbon black in the powder composition was 0.10 parts by weight. The carbon black was mechanically crushed and dispersed beforehand using a high-speed mixer. Except for these steps, the powder mixture was prepared in the same manner as in Example 1. The L value of this powder composition was 52, and the deviation of the L value was 0.008. Furthermore, the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹. -1 The near-infrared transmittance was 43%. The amount of coarse particles larger than 250 μm was essentially not measured (0.00 wt%).

[0134] The obtained powder composition was subjected to three-dimensional modeling under the same methods and conditions as in Example 1, except that the laser output was changed to 10W and the temperature was set to 202°C. The resulting three-dimensional model had a good appearance and was not a model with uneven color or spots. In addition, the tensile strength of the obtained three-dimensional model was 66 MPa. The obtained powder composition is suitable for modeling using a powder bed fusion bonding method with a laser beam wavelength of 400 nm to 2000 nm.

[0135] Except for using 10 kg of the powder composition, setting the laser output to 85 W and the temperature to 202°C, three-dimensional modeling was performed under the same conditions as in Example 1 using a Farsoon powder bed fusion bonding apparatus (Flight ST252P). The resulting three-dimensional model had a good appearance and was not characterized by uneven coloring or spots. Furthermore, the tensile strength of the obtained three-dimensional model was 81 MPa, exhibiting tensile strength equal to or greater than that of three-dimensional models using a CO2 laser.

[0136] [Comparative Example 1]

[0137] Except for the absence of carbon black, the powder composition was prepared in the same manner as in Example 2, and the L value of this powder composition was 94. Furthermore, the L value of the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹. -1 The near-infrared light transmittance is 86%. The resulting powder composition is not suitable for powder bed fusion bonding molding using laser beams with wavelengths of 400nm to 2000nm.

[0138] [Comparative Example 2]

[0139] Except that the amount of carbon black mixed was changed to 0.1 g, so that the carbon black in the powder composition was 0.001 parts by weight, the powder composition was prepared in the same manner as in Example 4. The L value of this composition was 92, and the deviation of the L value was 0.009. In addition, the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹. -1 The near-infrared light transmittance is 98%. The resulting powder composition is not suitable for powder bed fusion bonding molding using laser beams with wavelengths of 400nm to 2000nm.

[0140] [Comparative Example 3]

[0141] Without preparing a premixed powder, 20g of carbon black was directly mixed with 10kg of PPS resin particles to make the carbon black content in the powder composition 0.20 parts by weight. Otherwise, the powder composition was prepared in the same manner as in Example 1. The L value of this composition was 75, with a deviation of 0.020. Furthermore, the powder composition was measured using the diffuse reflectance method at 9500 cm⁻¹. -1 The near-infrared light transmittance is 83%. The amount of coarse particles with a diameter of 250 μm or larger is 2.20% by weight.

[0142] The obtained powder composition was subjected to three-dimensional modeling under the same methods and conditions as in Example 1, and spots were found in the resulting three-dimensional models. On a 10mm × 80mm surface plane of the three-dimensional model, 6 out of 12 spots with a diameter greater than 150μm were observed. The number of spots per 100cm² of surface area of ​​the three-dimensional model was [missing information]. 2The number of spots is 6. The resulting powder composition is not suitable for powder bed fusion bonding molding using lasers with beam wavelengths of 400nm to 2000nm.

[0143] Regarding Examples 1 to 5 and Comparative Examples 1 to 3, the characteristics are summarized in Table 1.

[0144]

[0145] Industry availability

[0146] This invention provides a method for manufacturing three-dimensional objects with excellent appearance using fiber lasers, and further provides a powder composition suitable for use as a material and a method for manufacturing it, thus making it suitable for a wide range of applications such as automotive, aerospace, industry, and medical.

Claims

1. A method for manufacturing a powder composition, said powder composition being a powder additive manufacturing method, said manufacturing method comprising the following steps (a) to (b): (a) In step 100 parts by weight of thermoplastic resin particles, 0.2 to 50 parts by weight of carbon black with an absorption capacity of DBP (dibutyl phthalate) of 10 ml / 100 g or more and 500 ml / 100 g or less are mixed to obtain a premixed powder (P1). (b) In the process of adding mixed thermoplastic resin particles to the premixed powder (P1) in such a way that the amount of carbon black is 0.02 to 5 parts by weight relative to 100 parts by weight of thermoplastic resin particles, a mixed powder (P2) is obtained.

2. The method for manufacturing the powder composition according to claim 1, further comprising step (c), (c) Step, in which the premixed powder (P1) or mixed powder (P2) is passed through a filter with an opening of 100 μm or more and 500 μm or less.

3. The method of manufacturing the powder composition according to claim 1, wherein step (a) and / or step (b) comprises mixing by applying shear force using a stirring blade.

4. A powder composition for use in powder additive manufacturing, comprising, relative to 100 parts by weight of thermoplastic resin particles, 0.02 to 5 parts by weight of carbon black with a DBP absorption of 10 ml / 100g or more and 500 ml / 100g or less, wherein the average particle size of the powder composition is 1 μm or more and 100 μm or less, and 9500 cm⁻¹ -1 The transmittance of near-infrared light is less than 75%.

5. The powder composition of claim 4, wherein, Large particles with a diameter of 250 μm or more account for less than 0.1% by weight.

6. The powder composition of claim 4, wherein, The thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylethermon sulfide, polyamide, polybutylene terephthalate and polyetheretherketone.

7. The powder composition of claim 4, wherein, The average particle size of the carbon black is 100 nm to 1000 nm.

8. The powder composition of claim 4, wherein, The thermoplastic resin particles contain 1 to 100 parts by weight of inorganic reinforcing material.

9. The powder composition of claim 8, wherein the inorganic reinforcing material is at least one selected from glass fiber, glass beads and carbon fiber.

10. The powder composition of claim 4, wherein the powder additive manufacturing method is a powder bed fusion bonding method using a laser with a beam wavelength of 400nm to 2000nm.

11. The powder composition of claim 10, wherein, Lasers with a beam wavelength of 400nm to 2000nm are lasers generated by fiber lasers.

12. A method for manufacturing a three-dimensional object, wherein, The powder composition is manufactured using any one of claims 1 to 3, and then a three-dimensional model is manufactured by powder additive manufacturing.

13. A method for manufacturing a three-dimensional object, wherein, A three-dimensional object is manufactured by irradiating the powder composition of any one of claims 4 to 11 with a laser beam of wavelength from 400 nm to 2000 nm and then bonding the powder with a powder bed fusion method.

14. A three-dimensional object, obtained by powder additive manufacturing, wherein spots with a diameter of 150 μm or larger observed on the surface of the three-dimensional object are present in an area of ​​less than 100 cm². 2 The surface area of ​​a three-dimensional object is less than 2.

15. A three-dimensional model obtained by powder additive manufacturing using a powder composition, wherein the powder composition is any one of claims 4 to 11, and when 12 test pieces with a width of 10 mm, a length of 80 mm, and a thickness of 4.0 mm are produced by powder additive manufacturing using the powder composition, the number of spots with a diameter of 150 μm or more observed on the 10 mm × 80 mm surface side plane is 2 or less per 12 test pieces. The test piece was prepared with the length of 80 mm in the X direction (the direction of recoater movement), the width of 10 mm in the Y direction (the direction orthogonal to the recoater's movement on the plane of movement), and the thickness of 4.0 mm in the Z direction (the direction perpendicular to the recoater's movement).

16. The three-dimensional model as claimed in claim 15, wherein it is a three-dimensional model for automotive parts, aerospace parts or robotic parts.

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