Method for producing a powder composition, powder composition, method for producing a three-dimensional object, and three-dimensional object

Abstract

Provided is a method for producing a powder composition to be used in a powder additive manufacturing system, the method having: (a) a step for blending 100 parts by weight of thermoplastic resin particles with 0.2-50 parts by weight of carbon black having a DBP (dibutyl phthalate) absorption amount of 10-500 ml / 100 g, and mixing to obtain a premix powder (P1); and (b) a step for obtaining a mixed powder (P2) by additionally blending thermoplastic resin particles with the premix powder (P1) so that the amount of carbon black is 0.02-5 parts by weight relative to 100 parts by weight of the thermoplastic resin particles. The present invention is capable of providing: a powder composition which can yield a three-dimensional shaped object at high speed and with high precision; and a method for producing a powder composition.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing three-dimensional objects at high speed and with high precision, suitable for a wide range of applications such as automobiles, aerospace, industry, and medical equipment, as well as a powder composition suitably used as a material for such manufacturing, and a method for manufacturing the same. [Background technology]

[0002] Three-dimensional printing (3D 3D) allows for highly flexible design and is widely used in applications such as automotive, aerospace, industrial, and medical fields. Powder deposition modeling is a suitable method for this type of printing due to its ability to achieve good mechanical strength and the elimination of the need for support structures. In recent years, application development has progressed, with consideration being given to functional prototypes to verify the performance of designed shapes, and even to final products that actually use 3D printed objects. This has led to increasing demand for faster manufacturing processes and higher precision in the resulting 3D printed objects.

[0003] Among powder addition manufacturing methods, the powder bed fusion method is a manufacturing method that involves sequentially repeating a thin-layer formation process in which resin particles are spread into a thin layer, and a cross-sectional shape formation process in which laser light is irradiated onto the formed thin layer to form a shape corresponding to the cross-sectional shape of the object to be manufactured, thereby bonding the powder. This method offers excellent manufacturing accuracy.

[0004] Among these, it is known that thermoplastic resin powder compositions containing carbon black are used in the production of three-dimensional objects by powder bed fusion fusion. For example, Patent Document 1 discloses a method for improving the accuracy of three-dimensional objects by adding carbon black to thermoplastic resin particles in order to reduce the electromagnetic reflectance of the three-dimensional object to 10% or less. Patent Document 2 also discloses polyarylene ketone powder to which carbon black has been added as a flame retardant and laser absorber. Furthermore, in powder bed fusion fusion fusion fusion using resin particles, a technique is known to speed up the manufacturing process by using a laser with a beam wavelength of 400 to 2000 nm, such as a fiber laser. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-162846 [Patent Document 2] Japanese Patent Publication No. 2007-39631 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a powder composition and a method for producing the same that can produce three-dimensional objects at high speed and with high precision. In particular, the object of the present invention is to provide a method and three-dimensional objects that produce highly accurate objects without color unevenness or spots using a powder bed fusion bonding method with a beam wavelength of 400 to 2000 nm, such as a fiber laser, which can accelerate the manufacturing process. [Means for solving the problem]

[0007] This invention was developed as a result of diligent research aimed at solving the aforementioned problems. Specifically, the present invention is as follows: <1> A method for producing a powder composition used in a powder addition manufacturing process having the following steps (a) to (b). (a) For every 100 parts by weight of thermoplastic resin particles, 0.2 to 50 parts by weight of carbon black with a DBP (dibutyl phthalate) absorption rate of 10 ml / 100g or more and 500 ml / 100g or less is blended. powder A step of mixing to obtain a pre-mixed powder (P1). (b) Add thermoplastic resin particles to the premixed powder (P1) such that the amount of carbon black is 0.02 to 5 parts by weight per 100 parts by weight of thermoplastic resin particles. Mix the powders A process to obtain a mixed powder (P2). <2> Furthermore, the process includes step (c), <1> A method for producing the powder composition described above. (c) A step of passing the pre-mixed powder (P1) or mixed powder (P2) through a filter having a mesh size of 100 μm or more and 500 μm or less. <3> The steps described in (a) and / or (b) above involve mixing with shear force using a stirring blade. <1> or <2> A method for producing the powder composition described above. <4> A powder composition containing 0.02 to 5 parts by weight of carbon black with a DBP absorption rate of 10 ml / 100 g to 500 ml / 100 g per 100 parts by weight of thermoplastic resin particles, wherein the average particle size is 1 μm to 100 μm, and the pressure is 9500 cm². -1 A powder composition used in additive manufacturing, wherein the transmittance of near-infrared light is 75% or less. <5> The amount of coarse particles with a particle size of 250 μm or more is 0.1% by weight or less. <4> The powder composition described above. <6> The thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylene sulfide, polyamide, polybutylene terephthalate, and polyether ether ketone. <4> or <5> The powder composition described above. <7> The average particle size of the carbon black is 100 nm to 1000 nm. <4> ~ <6> A powder composition as described in any of the following. <8> The thermoplastic resin particles are provided with 1 to 100 parts by weight of an inorganic reinforcing material. <4> ~ <7> A powder composition as described in any of the following. <9> The inorganic reinforcing material is at least one selected from glass fiber, glass beads, and carbon fiber. <8> The powder composition described above. <10> The aforementioned powder additive manufacturing method is a powder bed fusion method that uses laser light with a beam wavelength of 400 nm to 2000 nm. <4> ~ <9> A powder composition as described in any of the following. <11> Laser light with a beam wavelength of 400 nm to 2000 nm is laser light from a fiber laser. <10> The powder composition described above. <12> <1> ~ <3> A method for producing a powder composition by any of the methods described above, and then producing a three-dimensional object by a powder addition manufacturing method. A method for manufacturing a three-dimensional shaped object by irradiating the powder composition according to any one of <13><4> to <11> with laser light having a beam wavelength of 400 nm to 2000 nm and using a powder bed fusion bonding method. <14> Powder bed fusion fusion method using laser light with a beam wavelength of 400 nm to 2000 nm A three-dimensional shaped object obtained thereby, wherein the number of spots having a size diameter of 150 μm or more observed on the surface of the three-dimensional shaped object is 2 or less per 100 cm 2 of the surface area of the three-dimensional shaped object. <15>A powder composition according to any one of <4> to <11>, Powder bed fusion fusion method using laser light with a beam wavelength of 400 nm to 2000 nm by which, when 12 test pieces having a width of 10 mm, a length of 80 mm, and a thickness of 4.0 mm are produced such that the length of 80 mm is in the direction in which the recoater moves (X direction), the width of 10 mm is in the direction orthogonal to the moving direction of the recoater in the plane in which the recoater moves (Y direction), and the thickness of 4.0 mm is in the direction perpendicular to the moving direction of the recoater (Z direction), and the number of spots having a size diameter of 150 μm or more observed on the front surface plane of 10 mm × 80 mm is 2 or less per 12 test pieces, using Powder bed fusion fusion method using laser light with a beam wavelength of 400 nm to 2000 nm A three-dimensional shaped object obtained thereby. <16>The three-dimensional shaped object according to <15>, which is used for automotive parts, aerospace parts, or robot parts.

Effect of the Invention

[0008] According to the present invention, it is possible to provide a powder composition and a method for manufacturing the same, which can obtain a three-dimensional shaped object at high speed and with high precision. In particular, in a powder bed fusion bonding method using a laser having a beam wavelength of 400 to 2000 nm, such as a fiber laser, which enables the manufacturing process to be speeded up, a shaped object with good accuracy without color unevenness or spots can be obtained.

Mode for Carrying Out the Invention

[0010] Furthermore, the present invention relates to a method for producing a powder composition used in a powder addition manufacturing method, characterized by comprising the steps of (a) blending 0.2 to 50 parts by weight of carbon black with a DBP absorption amount of 10 ml / 100 g to 500 ml / 100 g with 100 parts by weight of thermoplastic resin particles and mixing to obtain a pre-mixed powder (P1), and (b) adding thermoplastic resin particles to the pre-mixed powder (P1) so that the amount of carbon black is 0.02 to 5 parts by weight per 100 parts by weight of thermoplastic resin particles to obtain a mixed powder (P2). It was found that by having the above steps (a) and (b), the three-dimensional molded object obtained by three-dimensional molding using the obtained powder composition was free from color unevenness and spots and was a highly accurate molded object, leading to the present invention.

[0011] In this invention, the carbon black is not particularly limited in type as long as it does not impair the properties of the powder composition, but it is especially preferred to use a carbon black that has excellent absorption properties for lasers with a beam wavelength of 400 to 2000 nm. Specifically, furnace black, channel black, acetylene black, thermal black, and Ketjen black are examples, and furnace black and acetylene black are more preferred because they have a high specific surface area and can exert their effect in smaller amounts, while furnace black is most preferred from the viewpoint of not impairing the properties of the powder composition.

[0012] In this invention, it is preferable to use neutral carbon black because it can reduce the amount of gas generated when irradiated with laser light. Furthermore, the amount of gas generated can be reduced by preheating and drying acidic carbon black before use.

[0013] DBP (dibutyl phthalate) absorption is an index used to evaluate oil absorption, specifically the amount of DBP absorbed into the surface of carbon black particles and the voids created by aggregated particles. It can be measured according to JIS K6217-4:2008. In this invention, the DBP absorption is between 10 ml / 100g and 500 ml / 100g. If the DBP absorption is 10 ml / 100g or less, the carbon black coating on the thermoplastic resin particle surface becomes uneven, the laser energy does not spread evenly, and uniform sintering of the thermoplastic resin particles does not occur. 15 ml / 100g or more is more preferable, 20 ml / 100g or more is even more preferable, and 25 ml / 100g or more is particularly preferable. Furthermore, if the DBP absorption is 500 ml / 100g or more, the specific surface area of ​​the carbon black increases, making it easier for the carbon black to aggregate and preventing the acquisition of a uniform three-dimensional object. A ratio of 400 ml / 100 g or less is more preferable, 300 ml / 100 g or less is even more preferable, and 200 ml / 100 g or less is particularly preferable.

[0014] The average particle size of the carbon black in this invention is preferably 10 to 1000 nm, and particularly preferably 100 to 1000 nm. A particle size of 100 nm or more allows the carbon black to be uniformly dispersed as primary particles in the powder composition, making it less prone to aggregation during recycling and enabling the stable production of three-dimensional objects. Furthermore, an average particle size of 1000 nm or less allows for sufficient energy absorption with a small amount of additive.

[0015] It is also possible to use carbon black that has been pre-degraded. Known methods can be used to degrade the carbon black, including mechanical degradement methods such as high-speed mixers and ball mills, air-jet pulverization methods such as jet mills, electrostatic treatment methods, and electromagnetic field treatment methods. The carbon black may also be passed through a suitable double-sided sieve to remove coarse particles and aggregates. Particularly preferred is mechanical degradement using a high-speed mixer. Mechanical pulverization using a high-speed mixer provides excellent uniformity in the powder composition and dispersion stability during recycling and fabrication, making it suitable for three-dimensional fabrication using lasers with beam wavelengths of 400-2000 nm, and allowing for the production of three-dimensional objects with excellent quality and mechanical properties.

[0016] In this invention, the amount of carbon black is 0.02 to 5 parts by weight when the amount of resin particles is 100 parts by weight. If the amount is less than 0.02 parts by weight, energy absorption will not occur, and the resin will not sinter sufficiently. 0.03 parts by weight or more is preferred, 0.05 parts by weight or more is more preferred, 0.08 parts by weight or more is even more preferred, and 0.1 parts by weight or more is particularly preferred. Furthermore, if the amount exceeds 5 parts by weight, the adhesion between resin particles weakens, and the strength of the three-dimensional molded object decreases. 3 parts by weight or less is preferred, 2 parts by weight or less is more preferred, 1 part by weight or less is even more preferred, and 0.5 parts by weight or less is particularly preferred.

[0017] In this invention, a thermoplastic resin is preferred because it exhibits excellent fluidity during melting. Examples of such thermoplastic resins include polyarylene sulfide resins, particularly polyphenylene sulfide resin (PPS), polyamide resins, particularly various types of nylon, such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 46, polyesters, such as polybutylene terephthalate resin (PBT), polycarbonate resin (PC), polyimide resin, polyetherimide resin, polyetherketone 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 the present invention may be any random copolymer, block copolymer, or a composition thereof. Among these, from the viewpoint of mechanical strength and heat resistance, it is preferable that it be at least one of polyarylene sulfide resin, polyamide resin, polybutylene terephthalate resin, polypropylene resin, or polyetherketone ketone resin, and polyarylene sulfide resin is particularly preferred in that it has low water absorption and excellent dielectric properties.

[0018] The melt viscosity of the thermoplastic resin used in this invention is preferably 150 Pa·s or more and 500 Pa·s or less. If the melt viscosity is less than 150 Pa·s, the strength of the fabricated three-dimensional object will be low, and if the melt viscosity is higher than 500 Pa·s, when the resin is melted by irradiating it with laser light, the molten resin will not penetrate to the lower layer, resulting in weak adhesion between layers and a significant decrease in the strength of the object in the height direction.

[0019] Here, a Toyo Seiki Capillograph 1C was used to measure the melt viscosity, with a die having a hole length of 10.00 mm and a hole diameter of 0.50 mm. Melt viscosity was determined by placing approximately 20 g of the sample into a cylinder set to a temperature 20°C higher than the melting point of the thermoplastic resin, holding it for 5 minutes, and then measuring the viscosity at a shear rate of 1216 sec. -1 The melt viscosity is the value obtained by measurement. 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.

[0020] Furthermore, it is preferable that the difference between the melting point and recrystallization temperature of the thermoplastic resin used in this invention is 30°C or higher. If the difference between the melting point and recrystallization temperature of the thermoplastic resin is less than 30°C, shrinkage and warping may occur as the resin melted by laser irradiation crystallizes. In powder bed fusion bonding, if warping occurs in the molten resin, the warped molten resin may be dragged when the powder layer is laminated on top of the molten resin, making it impossible to obtain a three-dimensional object with the desired shape.

[0021] Here, the recrystallization temperature refers to the peak temperature of the exothermic peak during crystallization when a thermoplastic resin is heated in a nitrogen atmosphere using a differential scanning calorimeter from 50°C to 40°C above the melting point at a rate of 20°C / min, held for 5 minutes, and then cooled down to 50°C at a rate of 20°C / min. If there are multiple peaks, the peak of the highest temperature peak was used as both the melting point and the crystallization temperature.

[0022] The average particle diameter of the thermoplastic resin particles of the present invention is preferably greater than 1 μm and less than or equal to 100 μm. A more preferable lower limit for the average particle diameter is 3 μm, even more preferably 5 μm, particularly preferably 8 μm, significantly preferably 10 μm, and most preferably 15 μm. A more preferable upper limit for the average particle diameter is 90 μm, even more preferably 85 μm, particularly preferably 80 μm, significantly preferably 75 μm, and most preferably 70 μm. If the average particle diameter exceeds 100 μm, uniformity is lost during powder bed fusion 3D printing, and the strength of the three-dimensional object is reduced. On the other hand, if the average particle diameter is less than 1 μm, static electricity causes aggregation of resin particles, similarly impairing uniformity during powder bed fusion and reducing the strength of the three-dimensional object.

[0023] In the present invention, the sphericity of thermoplastic resin particles is not particularly defined, but from the viewpoint of good moldability by the powder addition manufacturing method and excellent surface smoothness of the resulting three-dimensional molded object, 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.

[0024] In this invention, the sphericity of the thermoplastic resin particles is determined by observing 30 particles randomly from a scanning electron microscope image and calculating the ratio of their short axis to long axis.

[0025] In the production of thermoplastic resin particles in the present invention, there are no particular limitations, and particles obtained by polymerization can be used as thermoplastic resin particles, or particles can be obtained from resins molded into pellets, fibers, or films. Furthermore, depending on the form of the resin particles used, the pulverization treatment described below can be performed. Other methods include a spray-drying method after dissolving the raw materials in a solvent, a poor solvent precipitation method in which an emulsion is formed in a solvent and then brought into contact with a poor solvent, a liquid-drying method in which an emulsion is formed in a solvent and then the organic solvent is dried off, and a forced melt-kneading method in which a sea-island structure is formed by mechanically kneading the resin component to be particleized with a different resin component, and then the sea component is removed with a solvent. Among these, pulverization treatment is preferably used from the viewpoint of economy. There are no particular limitations on the pulverization treatment method, and examples include disc mills, jet mills, bead mills, hammer mills, ball mills, sand mills, turbo mills, and cryogenic grinding. Preferably, dry grinding such as turbo mills, jet mills, and cryogenic grinding is used, and more preferably, cryogenic grinding is used.

[0026] In the present invention, the powder composition may be a powder mixture of thermoplastic resin particles and carbon black, or the carbon black may be encapsulated within the thermoplastic resin particles. However, a powder mixture is preferred because it readily absorbs energy and is advantageous for melt sintering between the thermoplastic resin particles.

[0027] Particles containing carbon black can be obtained by a poor solvent precipitation method, in which a mixture of thermoplastic resin and carbon black is dissolved, an emulsion is formed in a solvent, and then it is brought into contact with a poor solvent; a liquid drying method, in which an emulsion is formed in a solvent and then the organic solvent is dried off; a forced melt kneading method, in which a sea-island structure is formed by mechanically kneading the resin component to be atomized with a different resin component, and then the sea component is removed with a solvent; or by melt-kneading carbon black into a polymer and then pulverizing it.

[0028] In the case of powder mixtures, mixing thermoplastic resin particles and carbon black is preferable because it allows for uniform mixing while breaking up carbon black aggregates by rotating a rotating blade attached to a container-rotating mixer. Other possible mixing methods include grinding using a ball mill or coffee mill, mixing with stirring blades such as a Nauter mixer or Henschel mixer, mixing by rotating the container using a V-type mixer, liquid-phase mixing in a solvent followed by drying, mixing by stirring with airflow using a flash blender, and mixing by spraying powder and / or slurry using an atomizer.

[0029] The present invention provides a method for producing a powder composition, comprising the steps of (a) blending 0.2 to 50 parts by weight of carbon black with 100 parts by weight of thermoplastic resin particles and mixing to obtain a pre-mixed powder (P1), and (b) adding thermoplastic resin particles to the pre-mixed powder (P1) so that the amount of carbon black is 0.02 to 5 parts by weight with 100 parts by weight of thermoplastic resin particles to obtain a mixed powder (P2). It has been found that by producing the pre-mixed powder (P1) in advance as a masterbatch, the aggregation of carbon black can be suppressed, and by obtaining the mixed powder (P2) using the pre-mixed powder (P1) as a raw material, a powder composition suitable for use in three-dimensional molding with homogeneously dispersed carbon black is obtained.

[0030] In the method for producing the powder composition of the present invention, the amount of carbon black blended with 100 parts by weight of thermoplastic resin particles in step (a) for obtaining the premixed powder (P1) is 0.2 to 50 parts by weight. If the amount is less than 0.2 parts by weight, the amount of thermoplastic resin particles relative to the carbon black is large in masterbatch production, making it difficult to disperse the carbon black, such as causing localized uneven distribution. 0.3 parts by weight or more is preferred, 0.5 parts by weight or more is more preferred, 1 part by weight or more is even more preferred, and 3 parts by weight or more is particularly preferred. If the amount exceeds 50 parts by weight, the carbon black concentration becomes high, and secondary aggregation of carbon black may occur. 40 parts by weight or less is preferred, 30 parts by weight or less is more preferred, 25 parts by weight or less is even more preferred, and 20 parts by weight or less is particularly preferred.

[0031] In step (a) of obtaining the pre-mixed powder (P1), it is preferable to mix until there are no color variations or inconsistencies visible to the naked eye. By obtaining a pre-mixed powder (P1) that is as homogeneous as possible, it becomes possible to obtain a homogeneous mixed powder (P2) in step (b).

[0032] In the method for producing the powder composition of the present invention, it is preferable to further include step (c) of passing the pre-mixed powder (P1) or mixed powder (P2) through a filter having a mesh size of 100 μm or more and 500 μm or less. When the pre-mixed powder (P1) is filtered, the effect of dissolving carbon black is also obtained, and a more homogeneous masterbatch can be obtained. When the mixed powder (P2) is filtered, the entire thermoplastic resin particle can be filtered, and coarse particles can be physically removed, so the generation of black coarse powder coated with carbon black can be suppressed. Therefore, it is more preferable to pass both the pre-mixed powder (P1) and the mixed powder (P2) through the filter.

[0033] In step (c) of the method for producing the powder composition of the present invention, the mesh size of the filter preferably used has a lower limit of 100 μm or more, which allows for the selective removal of only coarse particles without removing thermoplastic resin particles of a particle size suitable for three-dimensional molding. Therefore, 115 μm or more is more preferable, 130 μm or more is even more preferable, and 145 μm or more is particularly preferable. The upper limit is 500 μm or less, which allows for the removal of coarse particles that would be defects in the three-dimensional molded object. 400 μm or less is more preferable, 350 μm or less is even more preferable, and 300 μm or less is particularly preferable.

[0034] In the method for producing the powder composition of the present invention, steps (a) and / or (b) are preferably mixing that includes shear force using stirring blades. Carbon black tends to aggregate due to friction and static electricity during mixing, which can lead to problems with uniform mixing with thermoplastic resin particles. To solve this problem, mixing that includes shear force using stirring blades allows for mixing while breaking up the aggregates of carbon black, resulting in more uniform mixing. It is preferable that one or more stirring blades are mounted on a single container. When mixing thermoplastic resin particles and carbon black, the rotation speed of the container of the container-rotating mixer is preferably 3.5 rpm to 35 rpm, and more preferably 15 rpm to 30 rpm. The rotation speed of the stirring blades is preferably 100 rpm to 1,000 rpm, and more preferably 400 rpm to 700 rpm.

[0035] When an inorganic reinforcing material is included, it is preferable to perform the mixing in two stages. In the first stage, the carbon black is mixed with the thermoplastic resin particles, and in the second stage, the mixture from the first stage is mixed with the inorganic reinforcing material. If the inorganic reinforcing material and carbon black are mixed simultaneously, the carbon black will coat the surface of the inorganic reinforcing material as well, and the coating on the surface of the resin particles will not be sufficient. By mixing the carbon black and thermoplastic particles first, the carbon black can be coated on the particle surface, allowing the resin particles to sufficiently absorb the energy of the irradiated laser.

[0036] The average particle size of the powder composition of the present invention is 1 μm or more and 100 μm or less. The preferred lower limit of the average particle size is 3 μm, more preferably 5 μm, even more preferably 8 μm, particularly preferably 10 μm, and most preferably 15 μm. The preferred upper limit of the average particle size is 90 μm, more preferably 85 μm, even more preferably 80 μm, particularly preferably 75 μm, and most preferably 70 μm. If the average particle size of the powder composition exceeds 100 μm, uniformity is lost during powder lamination in the powder addition manufacturing method, and the strength of the three-dimensional object is reduced. On the other hand, if the average particle size is less than 1 μm, aggregation of the powder composition occurs due to static electricity, and similarly, uniformity is lost during powder lamination, and the strength of the three-dimensional object is reduced.

[0037] 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. If it exceeds 0.1% by weight, the three-dimensional molded object produced by the powder addition method using the powder composition will exhibit color unevenness and spots originating from the coarse particles. In terms of suppressing color unevenness and spots on the three-dimensional molded object, 0.05% by weight or less is preferred, 0.03% by weight or less is more preferred, 0.02% by weight or less is even more preferred, and 0.01% by weight or less is particularly preferred.

[0038] Coarse particles with a particle size of 250 μm or more refer to coarse particles that are captured by a sieve with a mesh size of 250 μm as defined in JIS Z8801-1 (2006) when the powder composition is passed through the sieve. These coarse particles may consist only of carbon black, or of carbon black and other components contained in the powder composition, or may consist only of components other than carbon black.

[0039] 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 a mesh size of 250 μm and measuring the difference in weight of the sieve before and after passing the composition through the sieve. Specifically, 2 kg of the powder composition is added to a sieve with a mesh size of 250 μm as specified in the Japanese Industrial Standard (JIS) JIS Z8801-1 (2006), and the sieve is vibrated until no more powder composition passes through it. The difference in weight of the sieve before and after passing the composition through the sieve is then defined as the weight of coarse particles with a particle size of 250 μm or larger. To prevent variations in the weighed value due to differences in the method of passing the coarse particles through the sieve, it is preferable to pass the composition through the sieve at room temperature (approximately 20-25°C), under atmospheric pressure, and at standard relative humidity (approximately 40-60%), either by leaving it still or by applying only slight vibrations. Therefore, weighing coarse particles should not be done by any method that intentionally breaks down coarse particles, such as physical treatments that crush, rub, or loosen the powder composition through a sieve, or by treatments that involve heating or cooling, treatment in a solvent, ultrasonic treatment, addition of surfactants, pH adjustment, electrophoresis, electroosmosis, or magnetic treatment.

[0040] In the present invention, it is preferable that carbon black is uniformly dispersed in the powder composition in a powder bed fusion bonding method using laser light, and the deviation of the L value can be used as an index to evaluate this uniform dispersion. The deviation of the L value is preferably 0.018 or less, and more preferably 0.015 or less. If the deviation of the L value exceeds 0.018, the carbon black is unevenly distributed on the resin surface, and the laser energy does not reach all the resin particles, reducing the accuracy of three-dimensional molding. The closer the deviation of the L value is to 0, the more uniformly dispersed the carbon black in the powder composition is, indicating a state of uniformity. The deviation of the L value can be obtained by taking three arbitrary samples from the powder composition, measuring the L values, and dividing the standard deviation of the L values ​​by the average of the three L values. The L value can be measured using a spectrophotometer.

[0041] After mixing thermoplastic resin particles and carbon black using the method described above, an inorganic reinforcing material can be added to the resulting mixture. Mixing can be performed using agitators such as Nauter mixers or Henschel mixers, or by rotating the container, such as with a V-type mixer or a cross-rotary mixer. However, a container-rotating mixer is preferred to prevent breakage of the inorganic reinforcing material. The preferred rotation speed of the container is 3.5 rpm to 35 rpm.

[0042] In the present invention, the L value of the powder composition is preferably 80 or less. A low L value of the powder composition enhances the effect of suppressing discoloration when the powder composition is subjected to thermal history. Furthermore, a low L value makes it easier to absorb laser light during fabrication using the powder bed fusion method, allowing the powder composition to be effectively laser sintered. Theoretically, the lower limit of the L value of the powder composition is 0, and the L value of the powder composition in the present invention is usually 10 or higher.

[0043] In this invention, the powder composition used for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm is a diffuse reflectance method used at 9500 cm². -1 The moldability can be evaluated by the transmittance of near-infrared light. In the diffuse reflectance method, a transmission spectrum is obtained from the specularly reflected light reflected from the surface of the powder composition and the diffusely reflected light transmitted through the interior of the powder composition, so its absorptivity can be evaluated by comparing the transmittance of a specific wavelength. The powder composition of the present invention can be measured using the diffuse reflectance method at 9500 cm². -1 The transmittance of near-infrared light is 75% or less. Having a transmittance of 75% or less improves the fabrication capabilities using laser light with a beam wavelength of 400 nm to 2000 nm. Preferably, it is 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less.

[0044] Furthermore, a 9500 cm² measurement was performed using the diffuse reflectance method for the powder composition. -1The transmittance of near-infrared light can be evaluated, for example, by installing a diffuse reflectance analyzer (DRS-8000) on a Fourier transform infrared spectrophotometer (IRPrestige-21) manufactured by Shimadzu Corporation, using a tungsten lamp as the light source, calcium fluoride as the beam splitter, and InGaAs (indium gallium arsenide) as the detector, filling the cell with potassium bromide and performing a near-infrared blank measurement, and then filling the cell with a powder composition sample and performing a near-infrared measurement.

[0045] Additives can 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, and flow aids, and they may be present either inside or outside the thermoplastic resin particles.

[0046] In this invention, the shape of the inorganic reinforcing material is preferably spherical, needle-shaped, plate-shaped, or fibrous, as it improves the mechanical properties of the three-dimensional object.

[0047] In the present invention, the inorganic reinforcing material added to the powder composition is not particularly limited, but materials with a maximum dimension of 1 μm to 400 μm can be used. To further improve the mechanical properties of the three-dimensional molded object, a dimension of 20 μm or more is more preferable, and 50 μm or more is even more preferable. Furthermore, from the viewpoint that the fluidity of the powder composition deteriorates as the dimension increases, a dimension of 200 μm or less is preferable, and 170 μm or less is even more preferable. Here, the maximum dimension is the average value obtained by observing the inorganic reinforcing material using a scanning electron microscope, randomly selecting 100 inorganic reinforcing materials from an image magnified 100 times, and measuring the length at which the distance between two points on the outer contour line of each inorganic reinforcing material is maximized.

[0048] The upper limit of the maximum dimension of the inorganic reinforcing material 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, more preferably 10 μm, and particularly preferably 15 μm. If the maximum dimension of the inorganic reinforcing material is 400 μm or less, a uniform powder surface can be formed during powder bed fusion 3D printing without impairing the fluidity of the powder composition. Furthermore, if the maximum dimension of the inorganic reinforcing material is 1 μm or more, an effect of improving the strength of the three-dimensional object made using the powder composition can be obtained.

[0049] When the inorganic reinforcing material is fibrous, the fiber length is the longest dimension, and the average of the longest dimensions is the average of the fiber lengths. Furthermore, it is preferable that the fiber diameter is 0.1 μm or more and 50 μm or less. The preferred lower limit of the fiber diameter is 0.1 μm, more preferably 0.5 μm, and particularly preferably 1 μm. The preferred upper limit of the fiber diameter is 5 μm, more preferably 40 μm, and particularly preferably 30 μm.

[0050] Examples of inorganic reinforcing materials in the present invention include talc, silica-containing compounds, minerals, glass fibers, glass beads, glass flakes, 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, but glass beads, glass fibers, and carbon fibers are more preferably used.

[0051] In this invention, the amount of inorganic reinforcing material is preferably 1 to 100 parts by weight, and more preferably 10 to 100 parts by weight, per 100 parts by weight of thermoplastic resin particles. The higher the proportion of reinforcing material, the greater the strength of the molded object. It is preferable to include 100 parts by weight or less of inorganic reinforcing material, as this suppresses a decrease in powder fluidity during three-dimensional molding.

[0052] The three-dimensional object of the present invention can be obtained by fabricating the powder composition of the present invention using a powder addition manufacturing method. The three-dimensional object of the present invention will be described below.

[0053] In the powder composition of the present invention, the carbon black is present on the surface of the thermoplastic resin powder. However, due to laser irradiation during molding, the thermoplastic resin powder melts, and the carbon black is encapsulated within the thermoplastic resin powder, either in powder form or in a molten state. As a result, the carbon black is retained within the three-dimensional object, and color fading of the three-dimensional object does not occur.

[0054] The carbon black content of the three-dimensional molded object 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 molded object produced by three-dimensional molding of the powder composition.

[0055] Carbon black contained in three-dimensional printed objects can be quantified, for example, by thermogravimetric analysis (TGA). Specifically, a small piece of the three-dimensional printed object is placed as a sample in the sample pan of a TGA apparatus, and the sample is heated at a constant rate until the thermoplastic resin thermally decomposes and volatilizes. The carbon black can then be quantified from the change in the weight of the sample. If quantification is not possible with TGA, it can be quantified by high-performance liquid chromatography (HPLC). A small piece of the three-dimensional printed object is dissolved in an appropriate solvent to prepare the sample, and when the sample solution is injected into an HPLC apparatus with an appropriate column and mobile phase, the carbon black is separated in the column, and the peak area is measured with a detector. Furthermore, a carbon black standard solution of known concentration is prepared, and a standard curve is created based on the peak area of ​​the standard sample. Finally, the carbon black content can be calculated by converting the peak area of ​​the sample to the carbon black concentration based on the standard curve.

[0056] In addition, in the powder composition of the present invention, carbon black is uniformly present on the surface of the thermoplastic resin powder, and there are almost no aggregates with a particle diameter of 250 μm or more containing carbon black. Therefore, even when melted by laser irradiation, it is uniformly melted, and a three-dimensional molded object with almost no color unevenness or spots can be obtained.

[0057] In the three-dimensional molded object of the present invention, the number of spots with a size diameter of 150 μm or more observed on the surface of the three-dimensional molded object is 2 or less per 100 cm 2 of the surface area of the three-dimensional molded object. The surface area of the three-dimensional molded object can be measured by a known method. For example, the three-dimensional molded object can be read by a 3D scanner to obtain three-dimensional CAD data, and methods such as calculating the surface area on software can be used. When the surface area of the three-dimensional molded object is less than 100 cm 2 , a plurality of three-dimensional molded objects can be combined, and the number of spots can be evaluated with a surface area of 100 cm 2 or more.

[0058] As a specific evaluation method for the spots present in the three-dimensional molded object, by the powder bed fusion bonding method, 12 test pieces with a width of 10 mm, a length of 80 mm, and a thickness of 4.0 mm are produced such that the length direction of 80 mm is the direction in which the recoater moves (X direction), the width direction of 10 mm is the direction orthogonal to the direction in which the recoater moves in the plane where the recoater moves (Y direction), and the thickness direction of 4.0 mm is the direction perpendicular to the plane where the recoater moves (Z direction). It can be evaluated by the number of test pieces with spots. It is preferable that the number of spots with a size diameter of 150 μm or more observed on the front surface plane of 10 mm × 80 mm is 2 or less per 12 test pieces. Whether there are spots on the three-dimensional molded object can be visually confirmed. The three-dimensional molded object is observed with an optical microscope, and if the size diameter is 150 μm or more, it is defined as a spot, and the average value of the major diameter and minor diameter of the spot is used as the size diameter. It is preferable that no spots with a size diameter of 150 μm or more are observed on the three-dimensional molded object.

[0059] The front surface refers to the topmost layer of the 10mm x 80mm plane of the test specimen. Furthermore, when a powder composition is fabricated using a powder bed fusion method, the dimensions of the fabricated object may differ from the set dimensions due to crystallization shrinkage. Therefore, the surface area calculated from the set dimensions is used for evaluation.

[0060] In this invention, a three-dimensional object with uneven coloring refers to a three-dimensional object with mottled patterns or gradients as a result of three-dimensional printing 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 scattered areas of different colors can be visually confirmed as a result of three-dimensional printing using a powder composition containing coarse particles with a particle size of 250 μm or more that include carbon black.

[0061] The three-dimensional fabricated objects of the present invention can be applied to automotive parts, aerospace parts, robot parts, medical device parts, auxiliary material parts, building parts, electrical and electronic equipment parts, and the like. In particular, the powder bed fusion method allows for the production of dense, highly mechanically sound, and highly heat-resistant three-dimensional fabricated objects, making it especially suitable for application to automotive parts, aerospace parts, and robot parts. [Examples]

[0062] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The various measurement methods are as follows.

[0063] [Average particle size of powder composition] The average particle size of the powder composition was measured using a laser diffraction / scattering particle size distribution analyzer (Nikkiso Co., Ltd., MT3300EXII) with a 0.5 wt% aqueous solution of polyoxyethylene cumylphenyl ether (trade name Nonal 912A, Toho Chemical Industry Co., Ltd.) as the dispersion medium. Specifically, the cumulative curve was determined by analyzing the scattered laser light using the microtrac method, with the total volume of the fine particles set to 100%. The average particle size was defined as the particle size at the point where the cumulative curve from the small particle size side reached 50% (median diameter: d50).

[0064] [Average particle size of carbon black] The average particle size of carbon black was determined by observing the powder composition using a scanning electron microscope (JSM-IT700HR) manufactured by JEOL Ltd. at a magnification of 10,000x for thermoplastic resin particles. The arithmetic mean of the particle sizes of 100 randomly selected carbon black particles from the resulting images was used as the number-mean particle size. Energy-dispersive X-ray spectroscopy was used to determine whether the material was carbon black.

[0065] [DBP absorption] The DBP absorption amount of carbon black was measured using an absorption meter (S410E, manufactured by Asahi Research Institute Co., Ltd.) in accordance with JIS K6217-4:2008, and the DBP absorption amount per 100g was defined as the DBP absorption amount.

[0066] [Diffuse reflection method of powdered composition for 9500 cm -1 [Transmittance of near-infrared light] A diffuse reflectance analyzer (DRS-8000) was installed on a Shimadzu Corporation Fourier transform infrared spectrophotometer (IRPrestige-21). Using a tungsten lamp as the light source, calcium fluoride as the beam splitter, and InGaAs (indium gallium arsenide) as the detector, a near-infrared blank measurement was performed by filling the cell with potassium bromide. Then, a powder composition sample was filled into the cell and a near-infrared measurement was performed at a wavelength of 9500 cm. -1 The transmittance of near-infrared light was determined.

[0067] [Color measurement] The L-values ​​of the powdered compositions were measured using a spectrophotometer (SE2000) manufactured by Nippon Denshoku Industries Ltd. The compositions were densely packed into a dedicated colorless, transparent quartz petri dish while being vibrated during measurement. The deviation of the L-values ​​was determined by taking three arbitrary samples from the powdered composition, measuring the L-values ​​of each sample, and dividing the standard deviation of these L-values ​​by the average of the three L-values.

[0068] [Amount of coarse particles with a particle size of 250 μm or larger] 2.0 kg of the powder composition was passed through a test sieve (250 μm opening) manufactured by Tokyo Screen Co., Ltd., as specified in the Japanese Industrial Standard (JIS) JIS Z8801-1 (2006). The amount of aggregate was weighed from the difference in weight of the sieve before and after passing through the sieve, and expressed as weight percent relative to 100% by weight of the powder composition. The powder composition was passed through the sieve only once.

[0069] [Color variations and spots on three-dimensional objects] To assess color unevenness and spots in three-dimensional printed objects, twelve test specimens measuring 10 mm in width, 80 mm in length, and 4.0 mm in thickness were fabricated using an Aspect Co., Ltd. powder bed fusion 3D printer (RaFaElII 150C-HT). The 80 mm length direction was aligned with the direction of the recoater's movement (X direction), the 10 mm width direction was perpendicular to the direction of the recoater's movement on the plane of recoater movement (Y direction), and the 4.0 mm thickness direction was perpendicular to the direction of recoater movement (Z direction). The number of three-dimensional printed objects that showed visible color unevenness was evaluated. Regarding spots on three-dimensional printed objects, we used a Keyence Corporation optical microscope (VHX-5000) and a Keyence Corporation objective lens VH-ZST (ZS-20) to evaluate the number of three-dimensional printed objects on a 10 mm x 80 mm front surface that exhibited spots with a diameter of 150 μm or larger.

[0070] [Measurement of tensile strength of three-dimensional objects] The tensile strength of the three-dimensional fabricated object was measured using a tensile test specimen (total length 170 mm, parallel section length 80 mm, parallel section width 10 mm, thickness 4 mm) prepared in accordance with ISO 527-1A, with the 170 mm length direction oriented as the X direction. The tensile strength in the X direction was measured using an A&D TENSIRON TRG-1250 universal tester. The tensile strength was determined by measuring under conditions of a gripping distance of 115 mm and a test speed of 0.5 mm / min, in accordance with JIS K7161 (2014). The measurement temperature was room temperature (23°C), and the number of measurements was n=10, from which the average value was calculated.

[0071] [Method for mixing powdered compositions] In the present invention, the method for mixing the powder composition involved mixing resin particles and carbon black for 20 minutes using a cross-rotary mixer equipped with a chopper in a container under nitrogen atmosphere and normal temperature and pressure conditions. The chopper was used at a rotation speed of 600 rpm. When an inorganic reinforcing material was to be added, the inorganic reinforcing material was added to a pre-mixed mixture of resin particles and carbon black, and then mixed for 20 minutes using a cross-rotary mixer under nitrogen atmosphere and normal temperature and pressure conditions. In this case, the chopper was not used for mixing.

[0072] [Manufacturing Example 1] In a 1-liter autoclave equipped with a stirrer, 1.00 mole of 47 wt% sodium hydroxide, 1.05 moles of 46 wt% sodium hydroxide, 1.65 moles of N-methyl-2-pyrrolidone (NMP), 0.45 moles of sodium acetate, and 5.55 moles of deionized water were charged. The mixture was then gradually heated to 225°C over approximately 2 hours under atmospheric pressure while passing nitrogen through it. After distilling off 11.70 moles of water and 0.02 moles of NMP, the reaction vessel was cooled to 160°C.

[0073] Next, 1.02 moles of p-dichlorobenzene (p-DCB) and 1.32 moles of NMP were added. The reaction vessel was sealed under nitrogen gas, and the temperature was increased in two stages while stirring at 400 rpm: from 160°C to 240°C at a rate of 0.4°C / min, and from 240°C to 270°C at a rate of 0.4°C / min. Ten minutes after reaching 270°C, 0.75 moles of water were 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 to remove the contents.

[0074] The contents were removed, diluted with 0.5 liters of NMP, and the solvent and solids were filtered off using an 80-mesh sieve. The resulting solids were washed several times with 1 liter of warm water, then 800 g of 0.45% by weight of calcium acetate monohydrate was added to the polyarylene sulfide in the solids and washed again with 1 liter of warm water. The mixture was then filtered to obtain the cake.

[0075] The resulting cake was dried under a nitrogen atmosphere at 120°C to obtain a polyarylene sulfide resin. This polyarylene sulfide resin was pulverized to obtain a powder composition with an average particle size of 50 μm and an L value of 97, and measured using the diffuse reflectance method at 9500 cm⁻¹. -1 We obtained polyphenylene sulfide (PPS) resin particles with 100% transmittance of near-infrared light.

[0076] [Manufacturing Example 2] In a 3L autoclave equipped with a helical ribbon-type stirring blade, 300g of ε-caprolactam (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polyamide monomer, 700g of polyethylene glycol (20,000 grade polyethylene glycol, weight-average molecular weight 18,600, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymer incompatible with polyamide, and 1000g of water were added to form a homogeneous solution. After that, the autoclave was sealed and purged with nitrogen. Subsequently, the stirring speed was set to 40 rpm and the temperature was raised to 210°C. At this time, the system pressure reached 10 kg / cm², and then the pressure was reduced to 10 kg / cm². 2 The pressure of the water vapor was controlled by slightly releasing it to maintain the desired temperature. After the temperature reached 210°C, 0.2 kg / cm³ was released. 2 The pressure was released at a rate of 1 minute. Then, the temperature was maintained for 1 hour while flowing nitrogen to complete polymerization. The mixture of polyamide powder and polyethylene glycol was then discharged into a 2000g water bath while the polyethylene glycol remained molten to obtain a slurry. After thoroughly homogenizing the slurry by stirring, it was filtered, and 2000g of water was added to the filtered product and washed at 80°C. The slurry liquid, after removing aggregates that had passed through a 100μm sieve, was filtered again to isolate the product. The filtered product was dried at 80°C for 12 hours to prepare 170g of polyamide 6 powder. The obtained polyamide powder had a sphericity of 92, an average particle size of 51μm, an L value of 97, and a diffuse reflectance of 9500cm² was used for the powder composition. -1 We obtained polyamide 6 (PA6) particles with 100% transmittance of near-infrared light.

[0077] [Example 1] 250 g of PPS resin particles obtained in Production Example 1 were weighed into a 1 L poly bag with 20 g of carbon black Asahi #15 (manufactured by Asahi Carbon Co., Ltd., furnace black, DBP absorption 42 ml / 100 g, L value 15, average particle size 122 nm), and mixed by hand until uniform in color. The mixture was then passed through a 300 μm sieve to homogenize it and obtain a pre-mixed powder (P1). 270 g of this pre-mixed powder (P1) was mixed with 9.75 kg of PPS resin particles so that the carbon black in the powder composition was 0.20 parts by weight. The mixture was then mixed for 20 minutes using a cross-rotary mixer equipped with a chopper in the container under nitrogen atmosphere and normal temperature and pressure conditions to obtain a mixed powder (P2). The chopper was used at a rotation speed of 600 rpm. This mixed powder (P2) was passed through a vibrating sieve equipped with a 212 μm sieve to prepare a powder composition for three-dimensional molding. At this time, the L value of this powder composition was 73, and the deviation of the L value was 0.009. Furthermore, the powder composition was measured using diffuse reflectance at 9500 cm². -1 The transmittance of near-infrared light was 58%. The amount of coarse particles with a particle size of 250 μm or larger was 0.01% by weight.

[0078] Using 1.5 kg of the obtained powder composition, a three-dimensional object was manufactured using a powder bed fusion fusion apparatus (RaFaElII 300C-HT) manufactured by Aspect Co., Ltd. The settings were as follows: a 60 W CO2 laser was used, the temperature was set to 260°C, the layer height was 0.1 mm, the laser scanning interval was 0.1 mm, the laser scanning speed was 5 m / s, and the laser output was 18 W. The appearance of the obtained three-dimensional object was good, and there were no objects with color unevenness or spots. The tensile strength of the obtained three-dimensional object was 49 MPa. The obtained powder composition is suitable for powder bed fusion fusion fusion using laser light with a beam wavelength of 400 nm to 2000 nm.

[0079] Using 10 kg of this powder composition, a three-dimensional object was fabricated using a Farsoon powder bed fusion system (Flight ST252P). The settings were as follows: a 300 W fiber laser was used, with a temperature setting of 258°C, a layer 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 appearance of the resulting three-dimensional object was good, with no objects exhibiting color unevenness or spots. Furthermore, the tensile strength of the resulting three-dimensional object was 54 MPa, which was equivalent to or greater than that of three-dimensional objects fabricated using a CO2 laser.

[0080] [Example 2] A pre-mixed powder (P1) was prepared in the same manner as in Example 1, except that the amount of carbon black added to 250 g of PPS resin particles was changed to 10 g, so that the carbon black in the powder composition was 0.13 parts by weight, and the carbon black was mechanically crushed beforehand using a high-speed mixer. Then, a mixed powder (P2) was obtained in the same manner as in Example 1, except that 7.25 kg of PPS resin particles were added. To this mixed powder (P2), 2.5 kg of glass fiber (EPG70MD-01N, manufactured by Nippon Electric Glass Co., Ltd., fiber length 75 μm) was added as an inorganic reinforcing material, and the mixture was mixed for 20 minutes using a cross-rotary mixer under a nitrogen atmosphere, at room temperature and pressure. A chopper was not used during this mixing. The obtained mixed powder was passed through a vibrating sieve equipped with a sieve with a mesh size of 212 μm to prepare a powder composition for three-dimensional molding. The L value of the obtained powder composition was 66, and the L value deviation was 0.006. Furthermore, the powder composition was subjected to 9500 cm using the diffuse reflection method. -1 The transmittance of near-infrared light was 40%. The amount of coarse particles with a particle size of 250 μm or larger was 0.02% by weight.

[0081] When the obtained powder composition was subjected to three-dimensional fabrication using the same method and conditions as in Example 1, the appearance of the obtained three-dimensional objects was good, and there were no objects with color unevenness or spots. The tensile strength of the obtained three-dimensional objects was 60 MPa. The obtained powder composition is suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0082] Using 10 kg of this powder composition, three-dimensional fabrication was performed using a Farsoon powder bed fusion apparatus (Flight ST252P) under the same conditions as in Example 1. The resulting three-dimensional objects had a good appearance, with no discoloration or spots. The tensile strength of the resulting three-dimensional objects was 62 MPa, which was equivalent to or greater than that of three-dimensional objects fabricated using a CO2 laser.

[0083] [Example 3] A powder composition for three-dimensional fabrication was prepared in the same manner as in Example 1, except that MA230 (manufactured by Mitsubishi Chemical Corporation, furnace black, DBP absorption 113 ml / 100 g, L value 9, average particle size 30 nm) was used as the carbon black. The L value of this powder composition was 63, and the L value deviation was 0.010. Furthermore, the powder composition was subjected to a 9500 cm³ diffuse reflection method. -1 The transmittance of near-infrared light was 49%. The amount of coarse particles with a particle size of 250 μm or larger was 0.02% by weight.

[0084] When the obtained powder composition was subjected to three-dimensional fabrication using the same method and conditions as in Example 1, the appearance of the resulting three-dimensional objects was good, and there were no objects with uneven coloring or spots. The obtained powder composition is suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0085] [Example 4] Polyamide 6 particles obtained by pulverizing polyamide 6 resin as thermoplastic resin particles (average particle size 51 μm, L value of 97 and 9500 cm using diffuse reflectance method of the particle composition) -1A powder mixture was prepared in the same manner as in Example 1, except that the amount of carbon black added in step (a) to obtain the pre-mixed powder (P1) was changed to 10 g, using a near-infrared light transmittance of 100%, so that the amount of carbon black in the powder composition was 0.10 parts by weight. The L value of this powder composition was 62, and the L value deviation was 0.008. The transmittance of the powder composition at 9500 cm⁻¹ using the diffuse reflectance method was 43%. The amount of coarse particles with a particle size of 250 μm or larger was 0.02% by weight.

[0086] Three-dimensional fabrication was performed using the obtained powder composition under the same method and conditions as in Example 1, except that the laser output was changed to 10W and the temperature setting to 202°C. The appearance of the obtained three-dimensional objects was good, and there were no objects with uneven coloring or spots. The obtained powder composition is suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400nm to 2000nm.

[0087] [Example 5] A powder mixture was prepared in the same manner as in Example 1, except that six polyamide particles obtained in Production Example 2 were used as thermoplastic resin particles, and 10 g of carbon black was added in step (a) to obtain the pre-mixed powder (P1), so that the amount of carbon black in the powder composition was 0.10 parts by weight, and the carbon black was mechanically crushed in advance using a high-speed mixer. The L value of this powder composition was 52, and the L value deviation was 0.008. The transmittance of near-infrared light at 9500 cm⁻¹ using the diffuse reflectance method for the powder composition was 43%. The amount of coarse particles with a particle size of 250 μm or larger was not substantially measured (0.00 wt%).

[0088] Three-dimensional fabrication was performed using the obtained powder composition under the same method and conditions as in Example 1, except that the laser output was changed to 10W and the temperature setting to 202°C. The resulting three-dimensional fabricated objects had a good appearance, with no discoloration or spots. The tensile strength of the obtained three-dimensional fabricated objects was 66 MPa. The obtained powder composition is suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0089] Using 10 kg of this powder composition, 3D fabrication was performed using a Farsoon powder bed fusion apparatus (Flight ST252P) under the same conditions as in Example 1, except that the laser output was changed to 85 W and the temperature setting to 202 °C. The resulting 3D fabricated objects had a good appearance, with no uneven coloring or spots. Furthermore, the tensile strength of the resulting 3D fabricated objects was 81 MPa, which was equivalent to or greater than that of 3D fabricated objects using a CO2 laser.

[0090] [Comparative Example 1] A powder composition was prepared in the same manner as in Example 2, except that carbon black was not included. The L value of this powder composition was 94. Furthermore, the powder composition was measured using the diffuse reflectance method at 9500 cm². -1 The transmittance of near-infrared light was 86%. The obtained powder composition is not suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0091] [Comparative Example 2] A powder composition was prepared in the same manner as in Example 4, except that the amount of carbon black was changed to 0.1 g, so that the carbon black in the powder composition was 0.001 parts by weight. The L value of this composition was 92, and the L value deviation was 0.009. Furthermore, the powder composition was subjected to diffuse reflection at 9500 cm. -1 The transmittance of near-infrared light was 98%. The obtained powder composition is not suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0092] [Comparative Example 3] A powder composition was prepared in the same manner as in Example 1, except that a pre-mixed powder was not prepared, and 20 g of carbon black was directly mixed with 10 kg of PPS resin particles to obtain a carbon black content of 0.20 parts by weight in the powder composition. The L value of this composition was 75, and the L value deviation was 0.020. Furthermore, the powder composition was subjected to diffuse reflectance at 9500 cm. -1 The transmittance of near-infrared light was 83%. The amount of coarse particles with a particle size of 250 μm or larger was 2.20% by weight.

[0093] When the obtained powder composition was subjected to three-dimensional fabrication using the same method and conditions as in Example 1, spots were observed on the resulting three-dimensional fabricated object. Of the 12 spots observed on the 10 mm × 80 mm front surface of the three-dimensional fabricated object, 6 had a size and diameter of 150 μm or larger. 2 The number of spots per area was 6. The obtained powder composition is not suitable for powder bed fusion fabrication using laser light with a beam wavelength of 400 nm to 2000 nm.

[0094] The characteristics of each of the above Examples 1-5 and Comparative Examples 1-3 are summarized in Table 1.

[0095] [Table 1] [Industrial applicability]

[0096] This invention provides a method for manufacturing three-dimensionally fabricated objects with excellent appearance using a fiber laser, as well as a powder composition suitably used as a material and a method for manufacturing the same. Therefore, it can be suitably used in a wide range of applications such as automotive, aerospace, industrial, and medical.

Claims

1. A method for producing a powder composition used in a powder addition manufacturing process having the following steps (a) to (b). (a) A step of obtaining a premixed powder (P1) by mixing 0.2 to 50 parts by weight of carbon black having a DBP (dibutyl phthalate) absorption amount of 10 ml / 100 g to 500 ml / 100 g and an average particle size of 100 nm to 1000 nm with 100 parts by weight of thermoplastic resin particles. (b) A step of adding thermoplastic resin particles to a premixed powder (P1) such that the amount of carbon black is 0.02 to 5 parts by weight per 100 parts by weight of thermoplastic resin particles, and then mixing the powders to obtain a mixed powder (P2).

2. A method for producing the powder composition according to claim 1, further comprising step (c). (c) A step of passing the pre-mixed powder (P1) or mixed powder (P2) through a filter having a mesh size of 100 μm or more and 500 μm or less.

3. The method for producing a powder composition according to claim 1, wherein step (a) and / or (b) is a mixing process that includes shearing force using a stirring blade.

4. A method for producing the powder composition according to claim 1, wherein in step (a) of obtaining the pre-mixed powder (P1), carbon black is added in an amount of 3 to 20 parts by weight.

5. The resulting powder composition has a yield of 9500 cm². －１ A method for producing the powder composition according to claim 1, wherein the transmittance of near-infrared light is 75% or less.

6. When the obtained powder composition is fabricated into a three-dimensional object using a powder bed fusion method with a laser beam wavelength of 400 nm to 2000 nm, the number of spots with a diameter of 150 μm or more observed on the surface of the three-dimensional object is such that the surface area of ​​the three-dimensional object is 100 cm². ２ A method for producing the powder composition according to claim 1, wherein the amount is two or less per unit.

7. A method for producing the powder composition according to claim 1, comprising a step of mixing an inorganic reinforcing material after step (b) above.

8. A method for producing the powder composition according to claim 7, comprising mixing 100 parts by weight of thermoplastic resin particles with 1 to 100 parts by weight of an inorganic reinforcing material.

9. A powder composition comprising 0.02 to 5 parts by weight of carbon black with a DBP absorption amount of 10 ml / 100 g to 500 ml / 100 g and an average particle size of 100 nm to 1000 nm per 100 parts by weight of thermoplastic resin particles, wherein the average particle size is 1 μm to 100 μm, and the composition is rated at 9500 cm². －１ A powder composition used in additive manufacturing, wherein the transmittance of near-infrared light is 75% or less.

10. The powder composition according to claim 9, wherein the coarse particles with a particle size of 250 μm or more constitute 0.1% by weight or less.

11. The powder composition according to claim 9, wherein the thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylene sulfide, polyamide, polybutylene terephthalate, and polyetheretherketone.

12. The powder composition according to claim 9, comprising 1 to 100 parts by weight of an inorganic reinforcing material per 100 parts by weight of the thermoplastic resin particles.

13. The powder composition according to claim 12, wherein the inorganic reinforcing material is at least one selected from glass fiber, glass beads, and carbon fiber.

14. The powder composition according to claim 9, wherein the powder additive manufacturing method is a powder bed fusion bonding method using laser light with a beam wavelength of 400 nm to 2000 nm.

15. The powder composition according to claim 14, wherein the laser light having a beam wavelength of 400 nm to 2000 nm is laser light from a fiber laser.

16. A method for producing a powder composition by any one of claims 1 to 8, and then producing a three-dimensional object by a powder addition manufacturing method.

17. A method for manufacturing a three-dimensional object by powder bed fusion bonding, comprising irradiating a powder composition according to any one of claims 9 to 15 with laser light having a beam wavelength of 400 nm to 2000 nm.

18. A three-dimensional object obtained by a powder bed fusion method using laser light with a beam wavelength of 400 nm to 2000 nm, wherein the number of spots with a size of 150 μm or larger observed on the surface of the three-dimensional object is such that the surface area of ​​the three-dimensional object is 100 cm². ２ Three-dimensional objects with two or fewer per unit area.

19. A powder composition according to any one of claims 9 to 15, wherein a three-dimensional object is obtained by a powder bed fusion fusion method using laser light with a beam wavelength of 400 nm to 2000 nm, using a powder composition that produces 12 test pieces with a width of 10 mm, a length of 80 mm, and a thickness of 4.0 mm, such that the direction of the length of 80 mm is the direction in which the recoater moves (X direction), the direction of the width of 10 mm is the direction perpendicular to the direction in which the recoater moves on the plane in which the recoater moves (Y direction), and the direction of the thickness of 4.0 mm is the direction perpendicular to the direction in which the recoater moves (Z direction), and the number of spots with a size diameter of 150 μm or more observed on the 10 mm × 80 mm front surface is 2 or less per 12 test pieces.

20. A three-dimensional object according to claim 19, used for automotive parts, aerospace parts, or robot parts.

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