Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/141—Processes of additive manufacturing using only solid materials
  • B29C64/153—Processes of additive manufacturing using only solid materials using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/264—Arrangements for irradiation
  • B29C64/268—Arrangements for irradiation using laser beams; using electron beams [EB]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/314—Preparation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
  • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/02—Fibres or whiskers
  • C08K7/04—Fibres or whiskers inorganic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/16—Solid spheres
  • C08K7/18—Solid spheres inorganic
  • C08K7/20—Glass
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds

Definitions

• the present invention relates to a method for quickly and accurately producing three-dimensional objects suitable for a wide range of applications, including automotive, aerospace, industrial, and medical applications, as well as a powder composition suitable for use as the material for such objects and a method for producing such objects.
• Three-dimensional printing allows for a high degree of freedom in designing shapes, and is therefore widely used in applications such as automotive, aerospace, industry, and medicine.
• Powder additive manufacturing is an ideal method for this type of printing, as it can achieve good mechanical strength and does not require support members.
• development of applications has progressed, with consideration being given to functional prototyping to confirm the performance of designed shapes, and to final product applications that actually use three-dimensional objects. There is a growing demand for faster manufacturing processes and higher precision in the resulting three-dimensional objects.
• powder bed fusion is a manufacturing method that involves sequentially repeating a thin layer formation process in which resin particles are spread into thin layers, and a cross-sectional shape formation process in which the formed thin layers are irradiated with laser light in a shape that corresponds to the cross-sectional shape of the object to be manufactured, thereby bonding the powder, resulting in excellent manufacturing precision.
• thermoplastic resin powder compositions containing carbon black are used in the production of three-dimensional objects using powder bed fusion.
• Patent Document 1 discloses a method of improving the precision of a three-dimensional object by adding carbon black to thermoplastic resin particles in order to reduce the electromagnetic reflectance of the object to 10% or less.
• Patent Document 2 discloses a polyarylene ketone powder to which carbon black has been added as a flame retardant and laser absorber.
• a technology is known for speeding up the production process in powder bed fusion using resin particles by using a laser with a beam wavelength of 400 to 2000 nm, such as a fiber laser.
• JP 2019-162846 A Japanese Patent Application Laid-Open No. 2007-39631
• the objective of the present invention is to provide a powder composition and a method for producing the same that can produce three-dimensional objects quickly and with high precision.
• the objective is to provide a method for producing highly precise objects without uneven color or spots, and a three-dimensional object, using a powder bed fusion method that uses a laser with a beam wavelength of 400 to 2000 nm, such as a fiber laser, which can speed up the manufacturing process.
• a method for producing a powder composition used in a powder additive manufacturing method comprising the following steps (a) to (b): (a) A step of blending 0.2 to 50 parts by weight of carbon black having a DBP (dibutyl phthalate) absorption capacity of 10 ml/100 g or more and 500 ml/100 g or less with 100 parts by weight of thermoplastic resin particles and mixing them to obtain a premixed powder (P1).
• DBP dibutyl phthalate
• thermoplastic resin particles A step of additionally blending thermoplastic resin particles with the premixed powder (P1) so that the amount of carbon black is 0.02 to 5 parts by weight per 100 parts by weight of the thermoplastic resin particles to obtain a mixed powder (P2).
• the steps (a) and/or (b) are mixing steps that involve shear force using a stirring blade.
• a powder composition for use in powder additive manufacturing comprising 0.02 to 5 parts by weight of carbon black having a DBP absorption of 10 ml/100 g or more and 500 ml/100 g or less per 100 parts by weight of thermoplastic resin particles, the powder composition having an average particle diameter of 1 ⁇ m or more and 100 ⁇ m or less, and a transmittance of near-infrared light at 9500 cm ⁇ 1 of 75% or less.
• thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylene sulfide, polyamide, polybutylene terephthalate, and polyether ether ketone.
• thermoplastic resin constituting the thermoplastic resin particles is at least one selected from polyarylene sulfide, polyamide, polybutylene terephthalate, and polyether ether ketone.
• carbon black has an average particle size of 100 nm to 1,000 nm.
• ⁇ 8> The powder composition according to any one of ⁇ 4> to ⁇ 7>, comprising 1 to 100 parts by weight of an inorganic reinforcing material relative to 100 parts by weight of the thermoplastic resin particles.
• the inorganic reinforcing material is at least one selected from glass fibers, glass beads, and carbon fibers.
• the powder additive manufacturing method is a powder bed fusion method using a laser beam having a beam wavelength of 400 nm to 2000 nm.
• the laser light having a beam wavelength of 400 nm to 2000 nm is laser light emitted by a fiber laser.
• a method for producing a three-dimensional object by powder bed fusion comprising irradiating the powder composition according to any one of ⁇ 4> to ⁇ 11> with laser light having a beam wavelength of 400 nm to 2000 nm.
• a three-dimensional object obtained by a powder additive manufacturing method in which the number of spots having a diameter of 150 ⁇ m or more observed on the surface of the three-dimensional object is two or less per 100 cm2 of the surface area of the three-dimensional object.
• the number of spots with a diameter of 150 ⁇ m or more observed on the 10 mm x 80 mm front plane is 2 or less per 12 test pieces.
• the three-dimensionally shaped object according to ⁇ 15> which is used as an automobile part, an aerospace part, or a robot part.
• the present invention provides a powder composition and a method for producing the same that can rapidly and accurately produce three-dimensional objects.
• powder bed fusion methods using lasers with beam wavelengths of 400 to 2000 nm, such as fiber lasers can be used to speed up the manufacturing process, resulting in highly accurate objects without uneven color or spots.
• the present invention will be described in detail below with reference to embodiments.
• the powder additive manufacturing method has excellent energy absorption and processability.
• the present invention has discovered that a powder composition containing 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 per 100 parts by weight of thermoplastic resin particles is suitable for powder bed fusion manufacturing using laser light with a beam wavelength of 400 nm to 2000 nm, based on the attribute of having excellent absorption of near-infrared light of 9500 cm -1 (low transmittance).
• the present invention relates to a method for producing a powder composition for use in a powder additive manufacturing method, characterized by comprising the steps of: (a) blending 0.2 to 50 parts by weight of carbon black having a DBP absorption of 10 ml/100 g or more and 500 ml/100 g or less with 100 parts by weight of thermoplastic resin particles and mixing them to obtain a premixed powder (P1); and (b) blending additional thermoplastic resin particles with the premixed powder (P1) so that the 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).
• the present invention was based on the discovery that by comprising the steps (a) and (b), three-dimensionally modeling using the obtained powder composition results in three-dimensional objects that are free of color unevenness or spots and are highly accurate.
• the type of carbon black used in the present invention is not particularly limited as long as it does not impair the properties of the powder composition, but carbon black with excellent absorption of lasers with beam wavelengths of 400 to 2000 nm is particularly preferred.
• Specific examples include furnace black, channel black, acetylene black, thermal black, and ketjen black. Furnace black and acetylene black are more preferred because they have a high specific surface area and can be effective in smaller amounts, and furnace black is most preferred because it is less likely to impair the properties of the powder composition.
• neutral carbon black it is preferable to use neutral carbon black, as this reduces 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.
• DBP (dibutyl phthalate) absorption is the amount of DBP absorbed on the surface of carbon black particles and in the voids created by agglomerated particles, i.e., an index for evaluating oil absorption. It can be measured in accordance with JIS K6217-4:2008.
• the DBP absorption is 10 ml/100 g or more and 500 ml/100 g or less. If the DBP absorption is 10 ml/100 g or less, the carbon black will not coat the thermoplastic resin particle surface uniformly, preventing the laser energy from reaching the entire surface and preventing uniform sintering of the thermoplastic resin particles.
• 15 ml/100 g or more is more preferable, 20 ml/100 g or more is even more preferable, and 25 ml/100 g or more is particularly preferable.
• the DBP absorption is 500 ml/100 g or more, the specific surface area of the carbon black will increase, making it prone to agglomeration and preventing the production of uniform three-dimensional objects. 400ml/100g or less is more preferable, 300ml/100g or less is even more preferable, and 200ml/100g or less is particularly preferable.
• the average particle size of the carbon black of the present invention is preferably 10 to 1,000 nm, and particularly preferably 100 to 1,000 nm. Having an average 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 likely to agglomerate during recycling molding, and enabling stable production of three-dimensional objects. Furthermore, having an average particle size of 1,000 nm or less allows sufficient energy absorption to be achieved with a small amount added.
• Carbon black that has been crushed in advance can also be used.
• Known methods can be used to crush carbon black, including mechanical crushing using a high-speed mixer or ball mill, airflow pulverization using a jet mill, electrostatic treatment, and electromagnetic field treatment. Coarse particles and agglomerates of carbon black can also be removed by passing the carbon black through an appropriate double-sided sieve.
• Mechanical crushing using a high-speed mixer is particularly preferred. Mechanical crushing using a high-speed mixer results in excellent uniformity within the powder composition and dispersion stability during recycled molding. It is also suitable for use in three-dimensional modeling using a laser with a beam wavelength of 400 to 2000 nm, allowing for the production of three-dimensional objects with excellent quality and mechanical properties.
• the amount of carbon black is 0.02 to 5 parts by weight per 100 parts by weight of resin particles. If it is less than 0.02 parts by weight, energy absorption will be insufficient and the resin will not be sintered 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. If it exceeds 5 parts by weight, the adhesion between the resin particles will weaken and the strength of the three-dimensional object will decrease. 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.
• thermoplastic resin used in the present invention is preferably a thermoplastic resin because it has excellent fluidity when melted.
• thermoplastic resins include polyarylene sulfide resins, particularly polyphenylene sulfide resins (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 resins (PBT), polycarbonate resins (PC), polyimide resins, polyetherimide resins, polyether ketone ketone resins, polyether ether ketone resins, polymethyl methacrylate, polytetrafluoroethylene resins, polyvinylidene fluoride resins, polyvinyl acetate, polyacetal, polysulfone resins, polystyrene resins, polylactic acid, polycaprolactone, methyl acrylate-methyl methacrylate copolymers, acrylonitrile-styrene cop
• the thermoplastic resin in the present invention may be a random copolymer, a block copolymer, or a composition thereof.
• it is preferably at least one of polyarylene sulfide resin, polyamide resin, polybutylene terephthalate resin, polypropylene resin, and polyether ketone ketone resin, and polyarylene sulfide resin is particularly preferred because of its low water absorption and excellent dielectric properties.
• the melt viscosity of the thermoplastic resin used in the present 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 three-dimensional object produced 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 into the layers below, resulting in weak adhesion between the layers and the risk of a significant decrease in the strength of the object in the height direction.
• the melt viscosity was measured using a Toyo Seiki Capillograph 1C die with a hole length of 10.00 mm and a hole diameter of 0.50 mm.
• the melt viscosity was measured by placing approximately 20 g of a sample into a cylinder set at a temperature 20 ° C higher than the melting point of the thermoplastic resin, holding the cylinder for 5 minutes, and then measuring the melt viscosity at a shear rate of 1216 sec -1 .
• 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.
• the difference between the melting point and recrystallization temperature of the thermoplastic resin used in the present invention is preferably 30°C or more. If the difference between the melting point and recrystallization temperature of the thermoplastic resin is less than 30°C, the molten resin may crystallize upon laser light irradiation, causing shrinkage and warping. In powder bed fusion bonding, if warping occurs in the molten resin, the warped molten resin may be dragged when a powder layer is layered on top of the molten resin, making it impossible to obtain a three-dimensional object with the desired shape.
• the recrystallization temperature refers to the apex 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 a temperature 40°C higher than the melting point at a rate of 20°C/min, held for 5 minutes, and then cooled to 50°C at a rate of 20°C/min. If there are multiple peaks, the apex of the highest peak is taken as the melting point and crystallization temperature.
• the average particle size of the thermoplastic resin particles of the present invention is preferably greater than 1 ⁇ m and less than 100 ⁇ m.
• a more preferred lower limit of the average particle size is 3 ⁇ m, even more preferably 5 ⁇ m, particularly preferably 8 ⁇ m, extremely preferably 10 ⁇ m, and most preferably 15 ⁇ m.
• a more preferred upper limit of the average particle size is 90 ⁇ m, even more preferably 85 ⁇ m, particularly preferably 80 ⁇ m, extremely preferably 75 ⁇ m, and most preferably 70 ⁇ m. If the average particle size exceeds 100 ⁇ m, uniformity will be lost during powder layering in a powder bed fusion 3D printer, reducing the strength of the three-dimensional object. On the other hand, if the average particle size is less than 1 ⁇ m, static electricity will cause the resin particles to aggregate, which will similarly reduce uniformity during powder layering and reduce the strength of the three-dimensional object.
• the sphericity which indicates the sphericity of the thermoplastic resin particles, is not particularly specified, but from the standpoint of good formability using powder additive manufacturing methods and excellent surface smoothness of the resulting three-dimensionally molded object, the sphericity is preferably 0.8 or more and 1 or less.
• the sphericity is more preferably 0.85 or more and 1 or less, and even more preferably 0.9 or more and 1 or less.
• thermoplastic resin particles in the present invention is determined by observing 30 particles randomly selected from a scanning electron microscope photograph and determining the ratio of their minor axis to their major axis.
• thermoplastic resin particles of the present invention are not particularly limited in their production process.
• Thermoplastic resin particles can be obtained from particles obtained by polymerization, or from resins molded into pellets, fibers, or films.
• the pulverization process described below can be performed depending on the form of the resin particles used.
• the pulverization method is not particularly limited, and examples include disk mills, jet mills, bead mills, hammer mills, ball mills, sand mills, turbo mills, and freeze pulverization. Dry pulverization, such as turbo mills, jet mills, and freeze pulverization, is preferred, with freeze pulverization being even more preferred.
• 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.
• a powder mixture is preferred because it is more likely to absorb energy and is advantageous for melt sintering between the thermoplastic resin particles.
• Particles containing carbon black can be obtained using a number of methods: the poor solvent precipitation method, in which a mixture of thermoplastic resin and carbon black is dissolved in advance, an emulsion is formed in a solvent, and then the mixture is brought into contact with a poor solvent; the submerged drying method, in which an emulsion is formed in a solvent and the organic solvent is then dried and removed; the forced melt kneading method, in which a sea-island structure is formed by mechanically kneading the resin component to be turned into particles 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.
• the poor solvent precipitation method in which a mixture of thermoplastic resin and carbon black is dissolved in advance, an emulsion is formed in a solvent, and then the mixture is brought into contact with a poor solvent
• the submerged drying method in which an emulsion is formed in a solvent
• thermoplastic resin particles and carbon black are preferably performed by rotating the rotating blades attached to a container rotary mixer, as this allows for uniform mixing while breaking down carbon black agglomerates.
• Other methods that can be used include mixing methods that involve grinding using a ball mill or coffee mill, mixing methods using stirring blades such as a Nauta mixer or Henschel mixer, mixing methods that rotate the entire container such as a V-type mixer, liquid phase mixing in a solvent followed by drying, mixing methods that use air currents such as a flash blender, and mixing methods that spray powder and/or slurry using an atomizer.
• the method for producing a powder composition of the present invention is characterized by 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 premixed powder (P1); and (b) blending additional thermoplastic resin particles with the premixed powder (P1) so that the carbon black is 0.02 to 5 parts by weight with respect to 100 parts by weight of thermoplastic resin particles to obtain a mixed powder (P2).
• the amount of carbon black blended per 100 parts by weight of thermoplastic resin particles in step (a) of obtaining the premixed powder (P1) is 0.2 to 50 parts by weight. If it is less than 0.2 parts by weight, the amount of thermoplastic resin particles relative to the carbon black in the masterbatch production will be too high, making the carbon black difficult to disperse, such as being locally unevenly dispersed.
• An amount of 0.3 parts by weight or more is preferred, more preferably 0.5 parts by weight or more, even more preferably 1 part by weight or more, and particularly preferably 3 parts by weight or more.
• the carbon black concentration will be high, and secondary aggregation of the carbon black may occur.
• An amount of 40 parts by weight or less is preferred, more preferably 30 parts by weight or less, even more preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less.
• step (a) of obtaining the premixed powder (P1) it is preferable to mix until there is no visible color unevenness or variation.
• step (b) of obtaining the premixed powder (P1) it is preferable to mix until there is no visible color unevenness or variation.
• the method for producing a powder composition of the present invention preferably further includes step (c) of passing the premixed powder (P1) or the mixed powder (P2) through a filter with a mesh size of 100 ⁇ m or more and 500 ⁇ m or less.
• Filtering the premixed powder (P1) also has the effect of dissolving the carbon black, allowing for a more homogeneous masterbatch to be obtained.
• filtering the mixed powder (P2) allows for filtering all of the thermoplastic resin particles, physically removing coarse particles and suppressing the generation 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 a filter.
• the lower limit of the mesh size of the filter preferably used in step (c) of the powder composition manufacturing method of the present invention is 100 ⁇ m or more, which makes it possible to selectively remove only coarse particles without removing thermoplastic resin particles with particle sizes suitable for three-dimensional modeling. Therefore, 115 ⁇ m or more is more preferable, 130 ⁇ m or more is even more preferable, and 145 ⁇ m or more is particularly preferable. If the upper limit is 500 ⁇ m or less, it will be possible to remove coarse particles that will cause defects in three-dimensional models. 400 ⁇ m or less is more preferable, 350 ⁇ m or less is even more preferable, and 300 ⁇ m or less is particularly preferable.
• steps (a) and/or (b) preferably involve mixing using an agitator blade, which involves shear force.
• Carbon black tends to agglomerate due to friction and static electricity during mixing, which can result in the problem of it not being mixed uniformly with the thermoplastic resin particles.
• mixing using an agitator blade involves shear force, which allows the carbon black to be mixed while breaking down agglomerates, resulting in more uniform mixing.
• one or more agitator blades are installed per container.
• the rotation speed of the container of the container rotary mixer is preferably 3.5 rpm to 35 rpm, more preferably 15 rpm to 30 rpm.
• the rotation speed of the agitator blade is preferably 100 rpm to 1,000 rpm, more preferably 400 rpm to 700 rpm.
• an inorganic reinforcing material When an inorganic reinforcing material is included, it is preferable to carry out the mixing in two separate steps, mixing the carbon black with the thermoplastic resin particles in the first mixing step, and then mixing the first mixture with the inorganic reinforcing material in the second mixing step. If the inorganic reinforcing material and carbon black are mixed simultaneously, the surface of the inorganic reinforcing material will also be coated with carbon black, and the surface of the resin particles will not be sufficiently coated. By mixing the carbon black with the thermoplastic particles first, it is possible to coat the particle surfaces with carbon black, allowing the resin particles to fully absorb the energy of the irradiated laser.
• the average particle size of the powder composition of the present invention is 1 ⁇ m or more and 100 ⁇ m or less.
• the preferred lower limit of the average particle size is 3 ⁇ m, more preferably 5 ⁇ m, even more preferably 8 ⁇ m, particularly preferably 10 ⁇ m, and most preferably 15 ⁇ m.
• the preferred upper limit of the average particle size is 90 ⁇ m, more preferably 85 ⁇ m, even more preferably 80 ⁇ m, particularly preferably 75 ⁇ m, and most preferably 70 ⁇ m. If the average particle size of the powder composition exceeds 100 ⁇ m, uniformity will be lost during powder layering in powder additive manufacturing methods, resulting in a decrease in the strength of the three-dimensional object. On the other hand, if the average particle size is less than 1 ⁇ m, static electricity will cause the powder composition to agglomerate, which will similarly cause uniformity to be lost during powder layering and a decrease in the strength of the three-dimensional object.
• the weight of coarse particles with a particle size of 250 ⁇ m or more is preferably 0.1 wt% or less. If it exceeds 0.1 wt%, three-dimensional objects manufactured using the powder composition by powder additive manufacturing will suffer from color unevenness and spots caused by the coarse particles. In order to suppress color unevenness and spots on three-dimensional objects, 0.05 wt% or less is preferred, 0.03 wt% or less is more preferred, 0.02 wt% or less is even more preferred, and 0.01 wt% or less is particularly preferred.
• Coarse particles with a particle diameter of 250 ⁇ m or more refer to coarse particles that are captured by a sieve with a mesh size of 250 ⁇ m as specified in JIS Z8801-1 (2006) when the powder composition is passed through the sieve.
• the coarse particles may be composed only of carbon black, or may be composed of carbon black and other components contained in the powder composition. It is also acceptable for coarse particles to be composed only of components other than carbon black.
• the weight of coarse particles with a particle size of 250 ⁇ m or more can be determined by passing the powder composition through a sieve with 250 ⁇ m openings and measuring the difference in weight of the sieve before and after passing through the sieve. Specifically, 2 kg of powder composition is added to a sieve with 250 ⁇ m openings as specified in the Japanese Industrial Standards (JIS) Z8801-1 (2006), and the sieve is vibrated until no powder composition passes through the sieve.
• the difference in weight of the sieve before and after passing through the sieve is defined as coarse particles with a particle size of 250 ⁇ m or more.
• coarse particles must not be weighed using any method that intentionally disintegrates them, such as physical treatments such as crushing, rubbing, or disintegrating the powder composition through a sieve, treatments involving heating or cooling, treatments in solvents, ultrasonic treatments, addition of surfactants, pH adjustments, electrophoresis, electroosmosis, or magnetic treatments.
• physical treatments such as crushing, rubbing, or disintegrating the powder composition through a sieve, treatments involving heating or cooling, treatments in solvents, ultrasonic treatments, addition of surfactants, pH adjustments, electrophoresis, electroosmosis, or magnetic treatments.
• the carbon black be uniformly dispersed in the powder composition, and the deviation in the L value can be used as an indicator of uniform dispersion.
• the deviation in the L value is preferably 0.018 or less, and more preferably 0.015 or less. If the deviation in the L value exceeds 0.018, the carbon black will be unevenly distributed on the resin surface, preventing the laser energy from reaching all of the resin particles, resulting in reduced accuracy in three-dimensional modeling. The closer the L value deviation is to 0, the more uniformly the carbon black in the powder composition is dispersed and the more uniform it is.
• the deviation in the L value can be determined by randomly taking three 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.
• the inorganic reinforcing material can be mixed into the resulting mixture.
• Mixing can be performed using a mixing method using a stirring blade, such as a Nauta mixer or Henschel mixer, or by rotating the entire container, such as a V-type mixer or cross rotary mixer.
• a container-rotating mixer is preferred to prevent breakage of the inorganic reinforcing material.
• the preferred container rotation speed is 3.5 to 35 rpm.
• 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 molding using the powder bed fusion method, allowing the powder composition to be effectively laser sintered.
• the lower limit of the L value of a powder composition is 0, and the L value of the powder composition of the present invention usually exhibits a value of 10 or more.
• the powder composition used in powder bed fusion molding using a laser beam with a beam wavelength of 400 nm to 2000 nm can have its moldability evaluated by its transmittance of near-infrared light at 9500 cm -1 using a 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, and thus its absorbency can be evaluated by comparing the transmittance at specific wavelengths.
• the powder composition of the present invention has a transmittance of near-infrared light at 9500 cm -1 using a diffuse reflectance method of 75% or less.
• a transmittance of 75% or less can improve moldability using a laser beam with a beam wavelength of 400 nm to 2000 nm.
• the transmittance is preferably 70% or less, more preferably 65% or less, and even more preferably 60% or less.
• the transmittance of the powder composition at 9500 cm ⁇ 1 near-infrared light using the diffuse reflectance method can be evaluated, for example, by installing a diffuse reflectance measurement device (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 a cell with potassium bromide to perform a near-infrared blank measurement, and then filling the cell with a powder composition sample to perform near-infrared measurement.
• DRS-8000 diffuse reflectance measurement device
• IRPrestige-21 Fourier transform infrared spectrophotometer manufactured by Shimadzu Corporation
• Additives may be added as long as they do not impair the properties of the powder composition of the present invention.
• additives include heat stabilizers, antioxidants, flame retardants, plasticizers, and flow aids, and they may be present either inside or outside the thermoplastic resin particles.
• the shape of the inorganic reinforcing material in the present invention is preferably spherical, needle-like, plate-like, fibrous, etc., as this improves the mechanical properties of the three-dimensionally shaped object.
• the inorganic reinforcing material added to the powder composition is not particularly limited, but materials with a maximum dimension of 1 ⁇ m or more and 400 ⁇ m or less can be used. To further improve the mechanical properties of three-dimensional objects, 20 ⁇ m or more is more preferable, and 50 ⁇ m or more is even more preferable. Furthermore, since the fluidity of the powder composition deteriorates as the dimension increases, 200 ⁇ m or less is preferable, and 170 ⁇ m or less is even more preferable.
• the maximum dimension is the average value of the values measured 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 maximum length between two points on the outer contour of each inorganic reinforcing material.
• the upper limit of the maximum dimension of the inorganic reinforcing material is preferably 400 ⁇ m, more preferably 390 ⁇ m, even more preferably 380 ⁇ m, and particularly preferably 370 ⁇ m.
• the lower limit is preferably 1 ⁇ m, more preferably 5 ⁇ m, even more preferably 10 ⁇ m, and particularly preferably 15 ⁇ m. If the maximum dimension of the inorganic reinforcing material is 400 ⁇ m or less, a uniform powder surface can be formed when the powder is layered in a powder bed fusion 3D printer without impairing the fluidity of the powder composition. Furthermore, if the maximum dimension of the inorganic reinforcing material is 1 ⁇ m or more, the strength of the three-dimensional object produced using the powder composition can be improved.
• the fiber length is the longest dimension, and the average value of the longest dimension is the average fiber length.
• the fiber diameter be 0.1 ⁇ m or more and 50 ⁇ m or less.
• the preferred lower limit of the fiber diameter is 0.1 ⁇ m, more preferably 0.5 ⁇ m, and particularly preferably 1 ⁇ m.
• the preferred upper limit of the fiber diameter is 5 ⁇ m, more preferably 40 ⁇ m, and particularly preferably 30 ⁇ m.
• Inorganic reinforcing materials used 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 oxide, magnesium oxide, potassium titanate, mica, asbestos, calcium sulfite, calcium silicate, molybdenum sulfide, boron fibers, and silicon carbide fibers, with glass beads, glass fibers, and carbon fibers being more preferred.
• 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.
• a blending amount of inorganic reinforcing material of 100 parts by weight or less is preferred, as it prevents a decrease in powder fluidity during three-dimensional molding.
• the three-dimensional object of the present invention can be obtained by molding the powder composition of the present invention using a powder additive manufacturing method.
• the three-dimensional object of the present invention is described below.
• the carbon black is present on the outer surface of the thermoplastic resin powder, but because the thermoplastic resin powder melts when irradiated with a laser during modeling, the carbon black remains in a powdered state inside the thermoplastic resin powder or on the inner surface, or is encapsulated in a molten state. This keeps the carbon black in the three-dimensional object, preventing discoloration of the three-dimensional object.
• the carbon black content of the three-dimensionally shaped 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 the carbon black contained in the powder composition and the weight of the carbon black contained in the three-dimensionally shaped object produced by three-dimensionally shaping the powder composition will be the same.
• the carbon black content of a three-dimensional object can be quantified, for example, using thermogravimetric analysis (TGA). Specifically, a small piece of the three-dimensional object is placed in the sample pan of a TGA instrument as a sample and heated at a constant rate until the thermoplastic resin thermally decomposes and volatilizes. The carbon black content can be quantified from the change in sample weight. If TGA is not feasible, high-performance liquid chromatography (HPLC) can be used. A small piece of the three-dimensional object is dissolved in an appropriate solvent to prepare the sample. An appropriate column and mobile phase are then installed in an HPLC instrument, and the sample solution is injected. The carbon black separates within the column, and the peak area is measured by 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 sample's peak area to the carbon black concentration based on the standard curve.
• TGA thermogravi
• the carbon black is uniformly distributed on the surface of the thermoplastic resin powder, and there are almost no agglomerates containing carbon black with particle diameters of 250 ⁇ m or more. Therefore, the composition is uniformly melted when irradiated with a laser, resulting in three-dimensional objects with almost no uneven color or spots.
• the three-dimensionally shaped object of the present invention is characterized in that the number of specks having a diameter of 150 ⁇ m or more observed on the surface of the three-dimensionally shaped object is two or less per 100 cm2 of the surface area of the three-dimensionally shaped object.
• the surface area of the three-dimensionally shaped object can be measured by a known method, for example, by scanning the three-dimensionally shaped object with a 3D scanner, converting it into three-dimensional CAD data, and calculating the surface area using software.
• the surface area of the three-dimensionally shaped object is less than 100 cm2
• multiple three-dimensionally shaped objects can be combined to evaluate the number of specks on a surface area of 100 cm2 or more.
• Specific evaluation methods for the presence of specks on three-dimensional objects include producing 12 test pieces, each 10 mm wide, 80 mm long, and 4.0 mm thick, using powder bed fusion bonding.
• the 80 mm length corresponds to the direction of recoater movement (X direction)
• the 10 mm width corresponds to the plane along which the recoater moves, perpendicular to the direction of recoater movement (Y direction)
• the 4.0 mm thickness corresponds to the direction perpendicular to the plane along which the recoater moves (Z direction).
• the evaluation can be performed by counting the number of test pieces with specks.
• the number of specks with a diameter of 150 ⁇ m or more observed on the 10 mm x 80 mm front surface plane be two or less per 12 test pieces.
• the presence of specks on three-dimensional objects can be confirmed visually.
• specks with a diameter of 150 ⁇ m or more are defined as specks, with the average of the long and short diameters of the specks being the size diameter. It is preferable that no specks with a diameter of 150 ⁇ m or more are observed on three-dimensional objects.
• the surface plane refers to the plane of the top layer of the 10 mm x 80 mm plane of the test piece. Furthermore, when a powder composition is three-dimensionally modeled using powder bed fusion, the dimensions of the set value may differ from the dimensions of the three-dimensional object actually obtained due to crystallization shrinkage, so the surface area calculated from the set value is used for evaluation.
• a three-dimensional object with uneven color refers to a three-dimensional object with a mottled pattern or gradation that is the result of three-dimensional modeling 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 the result of three-dimensional modeling using a powder composition containing coarse particles with a particle diameter of 250 ⁇ m or more that contain carbon black.
• the three-dimensional objects of the present invention can be used for automobile parts, aerospace parts, robot parts, medical equipment parts, secondary material parts, construction parts, electrical and electronic equipment parts, etc.
• the powder bed fusion method allows for the production of dense three-dimensional objects with high mechanical properties and high heat resistance, making them particularly suitable for use in automobile parts, aerospace parts, and robot parts.
• the average particle size of the powder composition was measured using a laser diffraction/scattering particle size distribution analyzer (MT3300EXII, manufactured by Nikkiso Co., Ltd.) and a 0.5 wt % aqueous solution of polyoxyethylene cumyl phenyl ether (trade name: Nonal 912A, manufactured by Toho Chemical Industry Co., Ltd.) as the dispersion medium. Specifically, a cumulative curve was obtained by analyzing scattered laser light using the Microtrack method, with the total volume of the fine particles obtained being 100%, and the particle size (median size: d50) at the point where the cumulative curve from the small particle size side reached 50% was taken as the average particle size.
• the average particle size of the carbon black was determined by observing the thermoplastic resin particles of the powder composition at a magnification of 10,000 times using a scanning electron microscope (JSM-IT700HR) manufactured by JEOL Ltd., and calculating the arithmetic mean value of particle sizes of 100 carbon black particles randomly selected from the photograph. Energy dispersive X-ray analysis was used to determine whether the material was carbon black.
• DBP absorption amount The DBP absorption amount of carbon black was measured using an absorption amount measuring device (S410E manufactured by Asahi Soken Co., Ltd.) in accordance with JIS K6217-4:2008, and the DBP absorption amount per 100 g was taken as the DBP absorption amount.
• a diffuse reflectance measurement device (DRS-8000) was installed on a Fourier transform infrared spectrophotometer (IRPrestige-21) manufactured by Shimadzu Corporation, and a tungsten lamp was used as the light source, calcium fluoride as the beam splitter, and InGaAs (indium gallium arsenide) as the detector. Potassium bromide was filled into a cell to perform a blank measurement of near-infrared light, and then a powder composition sample was filled into the cell to perform near-infrared measurement, and the transmittance of near-infrared light at a wavelength of 9500 cm was determined.
• the L value of the powder composition was measured using a spectrophotometer (SE2000) manufactured by Nippon Denshoku Industries Co., Ltd. Measurements were performed by densely packing the powder composition into a dedicated colorless, transparent quartz dish while applying vibration. The deviation of the L value was 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 L values of the three samples.
• SE2000 spectrophotometer
• Color unevenness on the three-dimensionally molded objects was evaluated by visually inspecting the number of three-dimensionally molded objects for which color unevenness was observed.
• an optical microscope (VHX-5000) manufactured by Keyence Corporation and an objective lens VH-ZST (ZS-20) manufactured by Keyence Corporation were used to evaluate the number of three-dimensionally molded objects on which spots with a diameter of 150 ⁇ m or more were observed on the front surface of the 10 mm ⁇ 80 mm three-dimensionally molded object.
• the tensile strength of the three-dimensional object was measured by preparing a tensile test piece (total length 170 mm, parallel portion length 80 mm, parallel portion width 10 mm, thickness 4 mm) conforming to ISO 527-1A so that the 170 mm length direction was the X direction, and measuring the tensile strength in the X direction using an A&D Tensilon universal testing machine (TENSIRON TRG-1250).
• the powder composition was prepared by mixing resin particles and carbon black for 20 minutes in a nitrogen atmosphere at room temperature and normal pressure using a cross rotary mixer equipped with a chopper in a container. The chopper was rotated at 600 rpm. When an inorganic reinforcing material was added, the inorganic reinforcing material was added to a mixture of resin particles and carbon black, and the mixture was mixed for 20 minutes in a nitrogen atmosphere at room temperature and normal pressure using a cross rotary mixer. The mixing was performed without using a chopper.
• the contents were removed and diluted with 0.5 liters of NMP.
• the solvent and solids were then filtered off using a sieve (80 mesh).
• the resulting solid was washed several times with 1 liter of warm water, then washed with 800 g of calcium acetate monohydrate (0.45% by weight relative to the polyarylene sulfide solid), and then washed again with 1 liter of warm water and filtered to obtain a cake.
• the resulting cake was dried at 120°C under a nitrogen stream to obtain a polyarylene sulfide resin.
• This polyarylene sulfide resin was pulverized to obtain polyphenylene sulfide (PPS) resin particles having an average particle size of 50 ⁇ m, an L value of 97, and a transmittance of 100% for near-infrared light at 9500 cm -1 as measured by a diffuse reflectance method for a powder composition.
• PPS polyphenylene sulfide
• the pressure was controlled by gently releasing water vapor to maintain the pressure at 10 kg/ cm2 .
• the pressure was released at a rate of 0.2 kg/ cm2 min.
• the temperature was then maintained for 1 hour while flowing nitrogen to complete the polymerization.
• the mixture of polyamide powder and polyethylene glycol was discharged into a 2,000 g water bath, with the polyethylene glycol still in a molten state, to obtain a slurry.
• the slurry was thoroughly homogenized by stirring and then filtered. 2000 g of water was added to the filter cake, followed by washing at 80°C.
• the slurry was then passed through a 100 ⁇ m sieve to remove aggregates, and the resulting filtered cake was filtered again.
• the isolated cake was dried at 80°C for 12 hours to produce 170 g of polyamide 6 powder.
• the resulting polyamide powder had a sphericity of 92, an average particle size of 51 ⁇ m, an L value of 97, and a near-infrared transmittance of 9500 cm -1 of 100% as measured by the diffuse reflectance method of the powder composition.
• Example 1 250 g of the PPS resin particles obtained in Production Example 1 and 20 g of Asahi #15 carbon black (furnace black, DBP absorption 42 ml/100 g, L value 15, average particle size 122 nm, manufactured by Asahi Carbon Co., Ltd.) were weighed into a 1 L plastic bag and mixed by hand to ensure uniform color. The mixture was then passed through a 300 ⁇ m mesh sieve to homogenize, yielding premixed powder (P1). 9.75 kg of PPS resin particles were blended with 270 g of this premixed powder (P1) so that the carbon black content in the powder composition was 0.20 parts by weight.
• Asahi #15 carbon black furnace black, DBP absorption 42 ml/100 g, L value 15, average particle size 122 nm, manufactured by Asahi Carbon Co., Ltd.
• the mixture was mixed for 20 minutes under nitrogen atmosphere at room temperature and pressure using a cross rotary mixer equipped with a chopper in the container to yield mixed powder (P2).
• the chopper rotation speed was 600 rpm.
• This mixed powder (P2) was then passed through a vibrating sieve equipped with a 212 ⁇ m mesh sieve to produce a powder composition for three-dimensional modeling.
• the L value of this powder composition was 73, with a deviation of 0.009.
• the transmittance of the powder composition at 9500 cm -1 near-infrared light measured using a diffuse reflectance method was 58%.
• the amount of coarse particles with a particle diameter of 250 ⁇ m or more was 0.01% by weight.
• a three-dimensional object was produced using a powder bed fusion system (RaFaElII 300C-HT) manufactured by Aspect Corporation.
• the conditions were a 60W CO2 laser, a temperature setting of 260°C, a build height of 0.1 mm, a laser scanning interval of 0.1 mm, a laser scanning speed of 5 m/s, and a laser output of 18 W.
• the appearance of the obtained three-dimensional object was good, with no uneven color or spots.
• the tensile strength of the obtained three-dimensional object was 49 MPa.
• the obtained powder composition is suitable for powder bed fusion modeling using a laser beam with a beam wavelength of 400 nm to 2000 nm.
• a three-dimensional object was produced using 10 kg of this powder composition in a Farsoon powder bed fusion machine (Flight ST252P).
• the conditions were a 300 W fiber laser, a temperature setting of 258°C, a build 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 uneven color or spots.
• the resulting three-dimensional object also had a tensile strength of 54 MPa, demonstrating a tensile strength equivalent to or greater than that of a three-dimensional object produced using a CO2 laser.
• Example 2 A premixed powder (P1) was prepared in the same manner as in Example 1, except that the amount of carbon black per 250 g of PPS resin particles was changed to 10 g, resulting in a carbon black content of 0.13 parts by weight in the powder composition, and the carbon black was mechanically crushed in advance 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 was blended with the premixed powder (P1).
• the resulting powder composition was used to perform three-dimensional modeling using the same method and conditions as in Example 1.
• the resulting three-dimensional model had a good appearance, with no uneven color or spots.
• the resulting three-dimensional model also had a tensile strength of 60 MPa.
• the resulting powder composition is suitable for powder bed fusion modeling, which uses laser light with a beam wavelength of 400 nm to 2000 nm.
• Example 3 A powder composition for three-dimensional modeling was prepared in the same manner as in Example 1, except that MA230 (furnace black, manufactured by Mitsubishi Chemical Corporation, 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, with an L value deviation of 0.010.
• the transmittance of the powder composition at near-infrared light of 9500 cm -1 using a diffuse reflectance method was 49%.
• the amount of coarse particles with a particle size of 250 ⁇ m or more was 0.02% by weight.
• the resulting powder composition was used to perform three-dimensional modeling using the same method and conditions as in Example 1.
• the resulting three-dimensional model had a good appearance, with no uneven color or spots.
• the resulting powder composition is suitable for powder bed fusion modeling, which uses laser light with a beam wavelength of 400 nm to 2000 nm.
• Example 4 A powder mixture was prepared in the same manner as in Example 1, except that polyamide 6 particles (average particle size 51 ⁇ m, particle composition L value of 97 using a diffuse reflectance method, and transmittance of near-infrared light at 9500 cm- 1 of 100%) obtained by pulverizing polyamide 6 resin were used as thermoplastic resin particles, and the amount of carbon black added in step (a) of preparing premixed powder (P1) was changed to 10 g, so that the carbon black content in the powder composition was 0.10 parts by weight.
• the L value of this powder composition was 62, with a deviation in L value of 0.008.
• the transmittance of the powder composition to near-infrared light at 9500 cm-1 using a diffuse reflectance method was 43%.
• the amount of coarse particles with a particle size of 250 ⁇ m or more was 0.02 wt%.
• the resulting powder composition was used to perform three-dimensional modeling using the same method and conditions as in Example 1, except that the laser output was changed to 10 W and the temperature setting to 202°C.
• the resulting three-dimensional model had a good appearance, with no uneven color or spots.
• the resulting powder composition is suitable for powder bed fusion modeling, which uses laser light with a beam wavelength of 400 nm to 2000 nm.
• Example 5 A powder mixture was prepared in the same manner as in Example 1, except that the polyamide 6 particles obtained in Production Example 2 were used as the thermoplastic resin particles, the amount of carbon black added in step (a) of preparing the premixed powder (P1) was 10 g, the carbon black content 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, with an L value deviation of 0.008.
• the transmittance of the powder composition at 9500 cm-1 near-infrared light using a diffuse reflectance method was 43%.
• the amount of coarse particles with a particle diameter of 250 ⁇ m or more was substantially not measured (0.00 wt%).
• the resulting powder composition was used to perform three-dimensional modeling using the same method and conditions as in Example 1, except that the laser output was changed to 10 W and the temperature setting to 202°C.
• the resulting three-dimensional model had a good appearance, with no uneven color or spots.
• the tensile strength of the resulting three-dimensional model was 66 MPa.
• the resulting powder composition is suitable for powder bed fusion modeling, which uses laser light with a beam wavelength of 400 nm to 2000 nm.
• Example 1 A powder composition was prepared in the same manner as in Example 2, except that carbon black was not added. The L value of this powder composition was 94. Furthermore, the transmittance of the powder composition at near-infrared light of 9,500 cm -1 , measured using a diffuse reflectance method, was 86%. The obtained powder composition is not suitable for powder bed fusion manufacturing, which uses a laser beam with a beam wavelength of 400 nm to 2,000 nm.
• 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 content in the powder composition was 0.001 parts by weight.
• the L value of this composition was 92, with an L value deviation of 0.009.
• the transmittance of the powder composition to near-infrared light at 9500 cm -1 measured using a diffuse reflectance method, was 98%.
• the obtained powder composition is not suitable for powder bed fusion manufacturing, which uses laser light with a beam wavelength of 400 nm to 2000 nm.
• Example 3 A powder composition was prepared in the same manner as in Example 1, except that a premixed powder was not prepared and 20 g of carbon black was directly mixed with 10 kg of PPS resin particles, resulting in a carbon black content of 0.20 parts by weight in the powder composition.
• the L value of this composition was 75, with an L value deviation of 0.020.
• the transmittance of the powder composition to near-infrared light at 9,500 cm -1 measured using a diffuse reflectance method, was 83%.
• the amount of coarse particles with a particle diameter of 250 ⁇ m or more was 2.20% by weight.
• the present invention provides a method for producing three-dimensional objects with excellent appearance when produced using a fiber laser, as well as a powder composition suitable for use as a material for such objects and a method for producing the same, making it suitable for use in a wide range of applications, including automotive, aerospace, industrial, and medical applications.

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