Method for manufacturing a three-dimensional object and three-dimensional object

Abstract

The present invention provides a method for manufacturing a three-dimensional object with high mechanical properties, and a three-dimensional object itself. [Solution] A method for manufacturing a three-dimensional object using a powder bed fusion bonding method with a powder composition containing thermoplastic resin powder with a D50 particle size of 1 μm to 100 μm, wherein the three-dimensional object is manufactured under the condition that the ratio of the amount of melting energy (Em) required to melt the powder composition to the amount of laser irradiation energy (El) satisfies the following equation (3), and the number of laser scans is 2 or more. TIFF2026114153000018.tif21170

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a three-dimensional object by forming a three-dimensional object using a powder bed fusion bonding method with thermoplastic resin powder, and to a method for manufacturing a three-dimensional object with high mechanical properties, and to a three-dimensional object. [Background technology]

[0002] Powder bed fusion (PBL) is a well-known method for creating three-dimensional objects. Generally, metal powders or thermoplastic resin powders are used as raw materials in PBL. This method involves selectively irradiating the powder surface of a build tank with laser light to melt and fuse the powders together, and then sweeping the powder from a supply tank into the build tank to build thin layers. These steps are repeated, and the object is then cooled after construction to obtain a three-dimensional object. Its features, such as the ability to selectively irradiate with laser light and the elimination of support structures, make it suitable for intricate fabrication, and it is expected to be used in precision machinery, medical devices, and other materials requiring high dimensional accuracy.

[0003] Three-dimensional fabricated objects are formed by melting or layering powders, which often limits the industrial applications of these objects because they cannot fully utilize the mechanical properties of the raw material powders. To address this issue, Patent Document 1 discloses a manufacturing method that improves the mechanical properties of a powder composition containing amorphous polyamide by applying a high amount of laser irradiation energy. Patent Document 2 discloses a manufacturing method that aims to improve the recyclability of unused powders by setting the powder bed temperature based on the melting point and crystallization temperature of the thermoplastic resin powder used in three-dimensional fabrication. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2024-530054 [Patent Document 2] Special Publication No. 2022-545634 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to obtain a three-dimensional molded object with excellent mechanical properties by a powder bed fusion bonding method using thermoplastic resin powder. Therefore, the present invention aims to provide a manufacturing method for obtaining a three-dimensional molded object with high mechanical properties, and a three-dimensional molded object. [Means for solving the problem]

[0006] To solve the above problems, the inventors have succeeded in providing a three-dimensional object with higher mechanical properties than three-dimensional objects manufactured by conventional manufacturing methods by adjusting the ratio of the amount of energy required to melt the powder composition to the amount of laser irradiation energy and by setting the number of laser scans to two or more. The present invention has the following configuration. <1> A method for manufacturing a three-dimensional object by powder bed fusion bonding using a powder composition containing thermoplastic resin powder with a D50 particle size of 1 μm to 100 μm, wherein the laser irradiation energy (El) defined by the following formula (1) and the melting energy (Em) defined by the following formula (2) satisfy the following formula (3).

[0007]

number

[0008] (In the formula, n represents the number of laser scans, n is an integer greater than or equal to 2, Pn is the laser output (W) during the nth laser scan, vn is the laser scanning speed (m / s) during the nth laser scan, ln is the laser scanning interval (m) during the nth laser scan, and h is the stacking height (mm).)

[0009]

number

[0010] (In the formula, C is the specific heat of the powder composition (J / g·K), Tm is the melting point of the thermoplastic resin powder contained in the powder composition (°C), Tb is the powder bed temperature of the powder composition (°C), Hf is the latent heat of fusion of the powder composition (J / g), and ρb is the bulk density of the powder composition (g / mL).)

[0011]

number

[0012] <2> The laser irradiation energy (El) is 900 J / mL or less. <1> A method for manufacturing a three-dimensional object as described above. <3> The laser output Pn is between 3W and 300W. <1> or <2> A method for manufacturing a three-dimensional object as described above. <4> The laser scanning speed vn is between 1000 mm / s and 30000 mm / s. <1> ~ <3> A method for manufacturing a three-dimensional object as described in any of the following. <5> The powder bed temperature Tb is 10°C or more lower than the melting point Tm of the thermoplastic resin powder contained in the powder composition. <1> ~ <4> A method for manufacturing a three-dimensional object as described in any of the following. <6> The powder bed temperature Tb is 150°C or higher. <1> ~ <5> A method for manufacturing a three-dimensional object as described in any of the following. <7> The thermoplastic resin constituting the thermoplastic resin powder is at least one selected from polyphenylene sulfide, polyamide, polyetheretherketone, polypropylene, polyester, polybutylene terephthalate, polyetherimide, polyamideimide, polyethersulfone, polyethylene, polyurethane, and polytetrafluoroethylene. <1> ~ <6> A method for manufacturing a three-dimensional object as described in any of the following. <8> With the total of thermoplastic resin powder and reinforcing filler being 100% by weight, the reinforcing filler contains 1% to 50% by weight. <1> ~ <7> A method for manufacturing a three-dimensional object as described in any of the following. <9> <1> ~ <8> A three-dimensional object obtained by any of the methods described herein.

Advantages of the Invention

[0013] According to the present invention, a method for manufacturing a three-dimensional object having high mechanical properties manufactured by a powder bed fusion bonding method and a three-dimensional object can be provided. In particular, by adjusting the ratio of the amount of energy required for melting the powder composition to the amount of laser irradiation energy and setting the number of laser scanning times to 2 or more, an effect of significantly improving the mechanical properties of three-dimensional shaping has been achieved.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram showing an example of an apparatus for manufacturing a three-dimensional object in the present invention.

Embodiments for Carrying Out the Invention

[0015] The thermoplastic resin constituting the thermoplastic resin powder in the present invention is a thermoplastic resin suitable for manufacturing three-dimensional molded objects by powder bed fusion bonding, and examples include polyphenylene sulfide, polyamide, polyetheretherketone, polypropylene, polyester, polybutylene terephthalate, polyetherimide, polyamideimide, polyethersulfone, polyethylene, polyurethane, and polytetrafluoroethylene or mixtures thereof. Polyphenylene sulfide, polyamide, polyetheretherketone, polypropylene, polyester, and polybutylene terephthalate are preferred because the resulting three-dimensional molded objects have excellent heat resistance, a clear difference between their melting point and crystallization temperature, and excellent moldability and reproducibility. Polyphenylene sulfide and polyamide are more preferred because they provide a significant improvement in mechanical properties in the manufacturing method of the present invention. Specific examples of such polyamides include polycaproamide (polyamide 6), polyundekaamide (polyamide 11), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polydecamethylene sevacamide (polyamide 1010), polydodecamethylene sevacamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sevacamide (polyamide 610), and polyhexamethylene dodecamide (poly Examples include amide 612), polydecamethylene adipamide (polyamide 106), polydodecamethylene adipamide (polyamide 126), polyhexamethylene terephthalamide (polyamide 6T), polydecamethylene terephthalamide (polyamide 10T), polydodecamethylene terephthalamide (polyamide 12T), polycaproamide / polyhexamethylene adipamide copolymer (polyamide 6 / 66), and polycaproamide / polylauroamide copolymer (6 / 12).Furthermore, among these, polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sevacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polycaproamide / polyhexamethylene adipamide copolymer (polyamide 6 / 66), and polycaproamide / polylauroamide copolymer (6 / 12) are particularly preferred in terms of the heat resistance of the molded product, with polycaproamide (polyamide 6) and polyhexamethylene adipamide (polyamide 66) being the most preferred.

[0016] The D50 particle size of the thermoplastic resin powder of the present invention is in the range of 1 to 100 μm. If the D50 particle size exceeds 100 μm, the size of the thermoplastic resin powder becomes larger than the layer height, resulting in a rough surface. If the D50 particle size is less than 1 μm, it is too fine and easily adheres to the recoater during molding, preventing the molding chamber from reaching the required temperature. Furthermore, the thermoplastic resin powder itself easily aggregates, preventing the effects of the present invention from being obtained. The upper limit of the D50 particle size of the polyamide powder is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less. The lower limit is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

[0017] In this invention, "melting" and "disintegration" of thermoplastic resin powder are treated as having the same meaning.

[0018] The D50 particle size of thermoplastic resin powder is the particle size at which the cumulative frequency from the smallest particle size side of the particle size distribution, as measured by a laser diffraction particle size distribution analyzer, reaches 50% (D50 particle size).

[0019] The particle size distribution of thermoplastic resin powder is expressed as the ratio of D90 to D10 in the particle size distribution, D90 / D10, and is preferably less than 5.0. A narrower particle size distribution is preferable because it eliminates differences in meltability during molding due to differences in the size of the thermoplastic resin powder, and also makes it easier to uniformly disperse the inorganic reinforcing material, resulting in a homogeneous molded product. Therefore, a D90 / D10 of less than 4.0 is more preferable, less than 3.0 is even more preferable, and less than 2.0 is particularly preferable. Theoretically, the lower limit is 1.0.

[0020] The D90 / D10 values, which represent the particle size distribution of the thermoplastic resin powder in the present invention, are obtained by dividing the particle size at which the cumulative frequency from the smallest particle size side of the particle size distribution measured by the laser diffraction particle size distribution analyzer described above reaches 90% (D90) by the particle size at which the cumulative frequency from the smallest particle size side reaches 10% (D10).

[0021] In the present invention, the sphericity of the thermoplastic resin powder is not particularly defined, but from the viewpoint of good formability by the powder bed fusion bonding method and excellent surface smoothness of the resulting three-dimensional molded object, the sphericity is preferably 80 to 100. If the sphericity is less than 80, the fluidity deteriorates and the surface of the molded object becomes rough. The sphericity is preferably 85 to 100, more preferably 90 to 100, even more preferably 93 to 100, particularly preferably 95 to 100, and significantly preferably 97 to 100.

[0022] The sphericity of the thermoplastic resin powder of the present invention is determined by observing 30 randomly selected thermoplastic resin powders from scanning electron microscope images and using the following formula based on their short and long axes.

[0023]

number

[0024] Note that S represents sphericity, a represents the major axis, b represents the minor axis, and n represents the number of measurements (30).

[0025] The D50 particle size of the powder composition, which includes thermoplastic resin powder and, if necessary, additives such as reinforcing fillers and flow aids described later, is preferably in the range of 1 to 100 μm. If the D50 particle size exceeds 100 μm, the size of the thermoplastic resin powder becomes larger than the layer height, resulting in a rough surface. If the D50 particle size is less than 1 μm, it is too fine and tends to adhere to the recoater during molding, preventing the molding chamber from reaching the required temperature. The upper limit of the D50 particle size of the powder composition is more preferably 90 μm or less, even more preferably 80 μm or less, and particularly preferably 70 μm or less. The lower limit is more preferably 5 μm or more, even more preferably 20 μm or more, and particularly preferably 30 μm or more.

[0026] The D50 particle size of the powder composition is the particle size (D50 particle size) at which the cumulative frequency from the smallest particle size side of the particle size distribution, as measured by a laser diffraction particle size distribution analyzer, reaches 50%.

[0027] The powder composition preferably exhibits high fluidity from the viewpoint of moldability. Furthermore, it is particularly preferable that the fluidity is high after being subjected to a thermal history equivalent to the molding temperature. Any known measurement method can be used as an indicator of this. Specifically, the angle of repose can be cited as an example. It is preferable that the angle is 60 degrees or less. More preferably 50 degrees or less, even more preferably 40 degrees or less, and particularly preferably 35 degrees or less. The lower limit is usually 20 degrees or more.

[0028] The three-dimensional molded object and the powder composition used to manufacture the three-dimensional molded object of the present invention may contain a reinforcing filler. Such a reinforcing filler may be, for example, silica (silicon dioxide) such as fused silica, crystalline silica, amorphous silica, alumina (aluminum oxide), alumina colloid (alumina sol), alumina white, calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, special calcium carbonate-based fillers, clay (aluminum silicate powder) such as nepheline syenite fine powder, calcined clay such as montmorillonite, bentonite, and silane-modified clay, silica-containing compounds such as talc, diatomaceous earth, and silica sand, and crushed natural minerals such as pumice powder, pumice balloons, slate powder, and mica powder. Examples include minerals such as barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, and graphite; glass-based fillers such as glass fibers, glass beads, glass flakes, and foamed glass beads; fly ash spheres; volcanic glass hollow bodies; synthetic inorganic hollow bodies; single-crystal potassium titanate; carbon fibers; carbon nanotubes; carbon hollow spheres; fullerenes; anthracite powder; artificial cryolite; titanium dioxide; magnesium oxide; basic magnesium carbonate; dolomite; potassium titanate; calcium sulfite; mica; asbestos; calcium silicate; molybdenum sulfide; boron fibers; and silicon carbide fibers. Preferably, silica, alumina, calcium carbonate powder, glass-based fillers, and titanium dioxide are used because they are hard and contribute to improving mechanical properties.

[0029] Such reinforcing fillers may be present outside or inside the thermoplastic resin powder. However, if the reinforcing fillers are present outside the thermoplastic resin powder, and the D50 particles of the reinforcing fillers are between 20 nm and 3000 nm in size, and are included in the substances listed below as examples of flow aids, then they shall be defined as flow aids.

[0030] Furthermore, the amount of reinforcing filler is preferably 1% to 50% by weight, and more preferably 5% to 50% by weight, based on the total weight of thermoplastic resin powder and reinforcing filler being 100% by weight. The higher the proportion of reinforcing material, the greater the strength of the molded object. It is preferable to include 50% by weight or less of inorganic reinforcing material, as this suppresses a decrease in powder fluidity during three-dimensional molding.

[0031] The three-dimensional molded object and the powder composition used to manufacture the three-dimensional molded object of the present invention may contain a flow aid. A flow aid refers to a substance that improves the powder flowability of the powder composition. Examples of fluidizing agents include silica (silicon dioxide) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide), alumina colloid (alumina sol), and alumina white; calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, and special calcium carbonate-based fillers; titanium dioxide, magnesium oxide, basic magnesium carbonate, potassium titanate fibers, boron fibers, and silicon carbide fibers. More preferably, silica, alumina, calcium carbonate powder, and titanium dioxide are used. Particularly preferred is silica, due to its hardness and ability to contribute to improved strength and fluidity. Examples of commercially available silica include the "AEROSIL" (registered trademark) series of fumed silica manufactured by Nippon Aerosil Co., Ltd., the "Rheoroseal" (registered trademark) series of dry silica manufactured by Tokuyama Corporation, and the X-24 series of sol-gel silica powder manufactured by Shin-Etsu Chemical Co., Ltd.

[0032] The D50 particle size of such a fluidizing agent is preferably between 20 nm and 3000 nm. The upper limit of the D50 particle size of the fluidizing agent is more preferably 2000 nm, even more preferably 1000 nm, particularly preferably 500 nm, significantly preferably 300 nm, and most preferably 200 nm. The lower limit is more preferably 30 nm, even more preferably 50 nm, particularly preferably 100 nm, significantly preferably 120 nm, and most preferably 140 nm. When the D50 particle size of the fluidizing agent is within the above range, it tends to improve the fluidity of the powder composition and allow the fluidizing agent to be uniformly dispersed in the powder composition.

[0033] The D50 particle size of a flow aid is the particle size (D50) at which the cumulative curve, obtained by analyzing the scattered light of a laser using dynamic light scattering, is calculated with the total volume of fine particles set to 100%, and the cumulative curve from the small particle size side reaches 50%.

[0034] The amount of such fluidizing agent is preferably 0% by weight, but preferably 2.0% by weight or less, based on 100% by weight of the thermoplastic resin powder or the total of the thermoplastic resin powder and reinforcing filler. The upper limit of the amount is more preferably 1.0% by weight or less, even more preferably 0.5% by weight or less, particularly preferably 0.1% by weight or less, and significantly preferably 0.05% by weight or less. The lower limit is preferably 0.01% by weight or more, and preferably 0.02% by weight or more. The inclusion of a fluidizing agent is undesirable because it can lead to deterioration of the appearance of the molded product due to sintering inhibition and a decrease in mechanical strength.

[0035] The three-dimensional molded object and the powder composition used to manufacture the three-dimensional molded object of the present invention may contain other additives. Examples of other additives include heat stabilizers, antioxidants, flame retardants, light stabilizers, plasticizers, and colorants, and these may be present either inside or outside the thermoplastic resin powder.

[0036] The difference between the crystallization temperature and melting point of the three-dimensional object and the powder composition used to manufacture the three-dimensional object of the present invention is preferably 20°C or more. If the difference between the crystallization temperature and melting point is small, the temperature conditions for manufacturing the three-dimensional object become severe, and warping and other defects are more likely to occur in the object, which is undesirable. The difference between the crystallization temperature and melting point of the powder composition is more preferably 25°C or more, even more preferably 30°C or more, particularly preferably 35°C or more, and most preferably 40°C or more.

[0037] In this invention, the melting point, crystallization temperature, and specific heat of the powder composition can be measured using a differential scanning calorimeter (DSC, for example, a DSCQ20 manufactured by TA Instruments).

[0038] The melting point and crystallization temperature are defined as the peaks of the endothermic peak associated with melting and the exothermic peak associated with crystallization when the polymer is heated once at a rate of 20°C / min from 30°C up to a temperature 30°C above its melting point under a nitrogen atmosphere, held for 1 minute, and then cooled to 30°C at a rate of 20°C / min and held for 1 minute. Furthermore, the latent heat of fusion of the powder composition can be calculated by integrating the region of the endothermic peak observed in the DSC curve (from the melting start temperature to the melting end temperature).

[0039] Regarding specific heat, the specific heat of the powder composition can be calculated according to the following formula, in accordance with the Japanese Industrial Standard (JIS standard) JIS K 7123 (2012).

[0040]

number

[0041] Note that H represents the difference in the vertical axis direction of the DSC curve between an empty container and a container containing the standard substance, h represents the difference in the vertical axis direction of the DSC curve between an empty container and a container containing the powder composition, mr represents the mass of the standard substance (mg), m represents the mass of the powder composition (mg), and Cr represents the specific heat of the standard substance (J / g·K). Alpha-alumina can be used as the standard substance.

[0042] The three-dimensional object and the powder composition used to manufacture the three-dimensional object of the present invention may be manufactured by any method, but can be prepared, for example, by powder mixing.

[0043] Suitable methods for powder mixing include manual mixing, as well as rotary mixers such as W-type mixers, V-type mixers, and drum-type mixers, and fixed-container mixers such as ribbon mixers.

[0044] Powder mixing is preferably carried out at a temperature at least 20°C lower than the melting point of the thermoplastic resin. If powder mixing is performed at any other temperature, the thermoplastic resin powder will melt during the mixing process. Furthermore, when adding reinforcing fillers, flow aids, or other additives, they may be mixed together with the thermoplastic resin powder or mixed separately.

[0045] A method for manufacturing three-dimensional objects using powder bed fusion bonding will be explained with reference to Figure 1.

[0046] (a) In step (a), the stage 2 of the tank 1 in which the molded object is formed is lowered.

[0047] (b) In step (b), the stage 4 of the tank 3 (hereinafter sometimes referred to as the supply tank), which is pre-filled with the powder composition P to be supplied to the tank 1 for forming the molded object, is raised to a height that allows for the supply of a sufficient amount of powder composition P to fill the tank 1 to a predetermined stacking height. Then, the recoater 5 is moved from the left end of the supply tank 3 to the right end of the tank 1, and the powder composition P is stacked in the tank 1. The direction parallel to the movement of the recoater 5 is the X direction, and the direction perpendicular to the direction of movement of the recoater 5 on the powder surface of the powder composition P is the Y direction. Reference numeral 7 indicates a coordinate system representing the X, Y, and Z directions. Reference numeral 8 indicates the plane direction in which the powder composition is stacked, and reference numeral 9 indicates the height direction in which the powder composition is stacked.

[0048] (c) In step (b), the powder composition P, which was filled into the tank 1 to a predetermined stacking height in step (b), is given meltable thermal energy 6 to selectively melt and sinter according to the molding data.

[0049] In the powder bed fusion method, a three-dimensional object 10 can be obtained by repeatedly performing steps (a) to (c) described above.

[0050] (c) As a method for selectively melting and sintering in step (c), for example, a selective laser sintering method is used in which a laser is irradiated into a shape corresponding to the cross-sectional shape of the object to be fabricated to bond the powder composition. Another example is a printing step in which an energy absorption accelerator or energy absorption inhibitor is printed into a shape corresponding to the cross-sectional shape of the object to be fabricated, and a selective absorption (or suppression) sintering method is used in which electromagnetic radiation is used to bond the resin powder.

[0051] The laser light used in selective laser sintering is not particularly limited as long as it does not impair the quality of the powder composition or the fabricated object. Examples include carbon dioxide lasers, YAG lasers, excimer lasers, He-Cd lasers, and semiconductor-pumped solid-state lasers. Among these, carbon dioxide lasers are preferred because they are easy to operate and control.

[0052] Furthermore, any electromagnetic radiation can be used in selective absorption (suppression) sintering as long as it does not impair the quality of the powder composition or the fabricated object, but infrared radiation is preferred because it is relatively inexpensive and provides energy suitable for fabrication. Also, the electromagnetic radiation may or may not be coherent.

[0053] Energy absorption enhancers are substances that absorb electromagnetic radiation. Examples of such substances include carbon fibers, copper hydroxyphosphate, near-infrared absorbing dyes, near-infrared absorbing pigments, metal nanoparticles, polythiophene, poly(p-phenylene sulfide), polyaniline, poly(pyrrole), polyacetylene, poly(p-phenylene vinylene), polyparaphenylene, poly(styrene sulfonate), poly(3,4-ethylenedioxythiophene)-poly(styrenephosphonate)p-diethylaminobenzaldehyde diphenylhydrazone, or conjugated polymers consisting of combinations thereof. These may be used individually or in combination.

[0054] Energy absorption inhibitors are substances that do not readily absorb electromagnetic radiation. Examples of such substances include materials that reflect electromagnetic radiation, such as titanium, heat-insulating powders such as mica powder and ceramic powder, and water. These can be used individually or in combination.

[0055] These selective absorbers or selective inhibitors may be used individually or in combination.

[0056] In the process of printing a selective absorbent or selective inhibitor in a shape corresponding to the cross-sectional shape of the object to be fabricated, known methods such as inkjet printing can be used. In this case, the selective absorbent or selective inhibitor may be used as is, or it may be dispersed or dissolved in a solvent before use.

[0057] The present invention aims to obtain a three-dimensional object with high mechanical properties by setting the laser irradiation energy El and the energy required to melt the powder composition Em to appropriate values. The present invention's method for manufacturing a three-dimensional object will now be described.

[0058] The laser irradiation energy El refers to the amount of energy that the laser irradiation of a powder bed fusion 3D printer imparts to the powder composition, and is calculated according to the following formula.

[0059]

number

[0060] Note that n represents the number of laser scans, and n is an integer greater than or equal to 2. Pn is the laser output (W) during the nth laser scan, vn is the laser scan speed (m / s) during the nth laser scan, ln is the laser scan interval (m) during the nth laser scan, and h is the layer height (mm). For all parameters, values ​​set in the software of any powder bed fusion 3D printer can be applied.

[0061] The laser output P is preferably between 3W and 300W. If it is less than 3W, melt sintering will be insufficient, and the mechanical properties of the resulting three-dimensional object will deteriorate. If it exceeds 300W, the laser penetrates deeper than the powder bed being laser-sintered, causing the powder composition to sinter, resulting in a three-dimensional object that is thicker than the set three-dimensional object, or increasing the amount of energy instantaneously applied to the powder composition, which can lead to charring of the three-dimensional object. From the viewpoint of obtaining a good shape for the resulting three-dimensional object and ensuring sufficient laser sintering, the lower limit of Pn is more preferably 4W or more, even more preferably 5W or more, and particularly preferably 6W or more. The upper limit is more preferably 200W or less, even more preferably 150W or less, particularly preferably 100W or less, significantly preferably 60W or less, and most preferably 30W or less.

[0062] The laser scanning speed vn is preferably between 1,000 mm / s and 30,000 mm / s. If it is less than 1,000 mm / s, the amount of energy instantaneously applied to the powder composition increases, which makes it prone to charring of the three-dimensional object. If it exceeds 30,000 mm / s, the melt sintering becomes insufficient, and the mechanical properties of the resulting three-dimensional object deteriorate. From the viewpoint of having a good shape for the three-dimensional object and sufficient laser sintering, the lower limit of v is more preferably 2,000 mm / s or more, even more preferably 3,000 mm / s or more, and particularly preferably 4,000 mm / s or more. The upper limit is more preferably 25,000 mm / s or less, even more preferably 20,000 mm / s or less, and particularly preferably 15,000 mm / s or less.

[0063] In powder bed fusion fusion, laser scanning is typically performed in a striped or zigzag pattern. The laser scanning interval is defined as the distance between two repeating laser trajectories in the laser scanning path.

[0064] The laser scanning interval ln is preferably 0.05 mm or more and 0.50 mm or less. If it is less than 0.05 mm, the amount of energy instantaneously applied to the powder composition increases, which makes it prone to charring of the three-dimensional object. If it exceeds 0.5 mm, the melt sintering becomes insufficient, and the mechanical properties of the resulting three-dimensional object deteriorate. From the viewpoint of having a good shape for the three-dimensional object and sufficient laser sintering, the lower limit of ln is more preferably 0.10 mm or more, even more preferably 0.15 mm or more, and particularly preferably 0.20 mm or more, and the upper limit is more preferably 0.40 mm or less, even more preferably 0.35 mm or less, and particularly preferably 0.30 mm or less.

[0065] The stacking height h represents the stacking height per layer in the powder bed fusion bonding method, and corresponds to the downward height of Stage 2 in Figure 1 mentioned above.

[0066] The layer height h is preferably 0.03 mm or more and 0.30 mm or less. If it is less than 0.03 mm, the layer is stacked at a height smaller than the particle size of the powder composition, making it difficult to stack the powder so that the powder bed is uniform. If it exceeds 0.30 mm, the height to be melt-sintered per layer of the three-dimensional object is too high, resulting in insufficient melt-sintering during laser irradiation and deterioration of the mechanical properties of the resulting three-dimensional object. The lower limit of h is more preferably 0.03 mm or more, even more preferably 0.05 mm or more, and particularly preferably 0.07 mm or more. The upper limit is more preferably 0.25 mm or less, even more preferably 0.20 mm or less, and particularly preferably 0.15 mm or less.

[0067] The number of laser scans n is the number of times the laser is irradiated onto the same location in the powder composition, and n is an integer of 2 or more. In this invention, the number of laser irradiations is 2 or more.

[0068] Here, as long as the laser is irradiated multiple times to the area to be laser-sintered per layer, the timing and order of irradiation do not matter. For example, if n is 2, the second laser scan may be performed immediately after the first laser scan, or a waiting period may be provided immediately after the first laser scan before the second laser scan. Also, for example, when laser-sintering is performed in three locations per layer, and the areas to be laser-sintered are designated as region A, region B, and region C, the second laser scan may be started after laser-sintering regions A, B, and C in the first laser scan, or region A may be scanned twice with a laser before starting the first laser scan of region B or region C.

[0069] In this invention, the number of laser scans n is 2 or more. By setting n to 2 or more, melt sintering proceeds sufficiently, and a three-dimensional object with high mechanical properties can be obtained. In particular, the shape of the obtained three-dimensional object is better and the mechanical properties are further improved compared to when three-dimensional printing is performed with high laser power or a slow laser scanning speed. The upper limit of n is preferably 5 or less. If n exceeds 5, excessive melt sintering occurs, which deteriorates the shape and mechanical properties of the three-dimensional object, and the manufacturing time of the three-dimensional object also increases. The upper limit of n is even more preferably 4 or less, and most preferably 3.

[0070] El can be calculated using the above parameters.

[0071] Furthermore, in equation (6), when n is 2 or greater, if Elk is the laser irradiation energy amount for the kth time, Pk is the laser output, vk is the laser scanning speed, and lk is the laser scanning interval, then Elk can be expressed by the following formula.

[0072]

number

[0073] It is preferable to set the various parameters in equation (7) such that Elk+1 ≤ Elk. If Elk+1 > Elk, that is, if the laser irradiation energy for the second and subsequent laser irradiations is greater than the laser irradiation energy for the first laser irradiation, the powder composition that was melted in the first laser irradiation will be irradiated with a stronger energy than the first time, which may cause excessive sintering of the powder composition and deterioration of the shape of the resulting three-dimensional object.

[0074] For example, if n=2, and during the first laser scan the parameters are set to P1:19W, v1:5000mm / s, l1:0.2mm, and h:0.1mm, and then during the second laser scan the parameters are changed to P2:8W without changing the other parameters, then El1 is 190J / mL and El2 is 80J / mL, so El is calculated to be 270J / mL.

[0075] Furthermore, the layering height h will be the same regardless of the number of times n is performed, from the perspective of the manufacturing method in which laser irradiation is performed after layering of the powder composition.

[0076] The upper limit of El is preferably 900 J / mL or less. If it exceeds 900 J / mL, the amount of energy instantaneously applied to the powder composition increases, which can lead to problems such as charring of the three-dimensional object. If a three-dimensional object with high mechanical properties can be obtained, it is preferable to irradiate it with a small amount of laser energy. The upper limit of El is more preferably 800 J / mL or less, even more preferably 700 J / mL or less, and particularly preferably 600 J / mL or less.

[0077] The required energy amount Em refers to the amount of energy needed to melt the powder composition and is calculated according to the following formula.

[0078]

number

[0079] Here, C represents the specific heat (J / g·K) of the powder composition, Tm represents the melting point (°C) of the thermoplastic resin powder contained in the powder composition, Tb represents the powder bed temperature (°C), Hf represents the latent heat of fusion (J / g) of the powder composition, and ρb represents the bulk density (g / mL) of the powder composition.

[0080] In the present invention, the powder bed temperature Tb refers to the shaping temperature during three-dimensional shaping, and is the temperature of the powder bed of the powder composition present at the location where laser irradiation is performed. The powder bed temperature Tb is preferably 10°C or more lower than the melting point Tm of the thermoplastic resin powder contained in the powder composition, that is, the difference between Tb and Tm is 10°C or more. In the case of three-dimensional shaping by the powder bed melting and bonding method, usually, three-dimensional shaping is performed so that Tb < Tm so that the powder composition does not melt. When the difference between Tb and Tm is less than 10°C, even if the fusion of the powder composition not used in the production of the three-dimensional shaped object does not occur, three-dimensional shaping can be performed with a small amount of laser irradiation energy, and the effects of the present invention cannot be fully exhibited. By setting the difference between Tb and Tm to 10°C or more, the effects of the present invention can be fully exhibited, and while suppressing the deterioration of the powder composition not used in the production of the three-dimensional shaped object, a three-dimensional shaped object having high mechanical properties can be obtained.

[0081] From the viewpoint of easily exhibiting the effects of the present invention, the difference between Tb and Tm is more preferably 15°C or more, further preferably 20°C or more, and particularly preferably 25°C or more.

[0082] Regarding the upper limit of the difference between Tb and Tm, it is preferably set so that Tb is 150°C or more. When Tb is 150°C or less, since the thermoplastic resin powder contained in the powder composition is rapidly cooled, there is a possibility that the crystallization of the three-dimensional shaped object does not proceed uniformly and a three-dimensional shaped object with high mechanical properties cannot be obtained.

[0083] From the viewpoint of more uniform progress of the crystallization of the three-dimensional shaped object, Tb is more preferably 160°C or more, further preferably 170°C or more, and particularly preferably 180°C or more. The upper limit of Tb may be set so as to satisfy the above-mentioned difference between Tb and Tm, but is usually 300°C or less. Furthermore, if Tb is set to a temperature lower than the crystallization temperature Tc of the thermoplastic resin powder contained in the powder composition, warping will occur in the three-dimensional molded object. Therefore, Tb is usually set to a temperature higher than Tc.

[0084] In this invention, the laser irradiation energy El and the melting energy Em satisfy the following formula.

[0085]

number

[0086] If El / Em < 4.0, the powder composition does not receive sufficient laser irradiation energy, and three-dimensional fabrication with high mechanical properties cannot be obtained. If El / Em > 15.0, the powder composition receives excessive laser irradiation energy, and the resin deteriorates due to crosslinking and decomposition by the laser irradiation, resulting in a decrease in mechanical properties.

[0087] The lower limit of El / Em is preferably 4.2 or higher, and more preferably 4.4 or higher. The upper limit of El / Em is preferably 12.0 or lower, and more preferably 10.0 or lower.

[0088] The surface roughness of the three-dimensional molded object of the present invention is preferably 20 μm or less. Since a smaller surface roughness results in better adhesion between the molded objects, the surface roughness of the molded object is more preferably 18 μm or less, even more preferably 15 μm or less, particularly preferably 12 μm or less, and most preferably 10 μm or less. The lower limit is not particularly limited, and a smaller value is preferred, but the lower limit is usually 1 μm.

[0089] The surface roughness of the fabricated object is calculated by observing the surface of the fabricated object with an optical microscope, creating a three-dimensional image of the surface irregularities using the automatic synthesis mode, obtaining the cross-sectional height profile over a length of 1 mm or more, and then calculating the surface roughness Ra using the arithmetic mean.

[0090] 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]

[0091] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0092] (1) D50 particle size of thermoplastic resin powder A dispersion of approximately 100 mg of thermoplastic resin powder, pre-dispersed in approximately 5 mL of deionized water, was added to a Nikkiso Co., Ltd. laser diffraction particle size distribution analyzer (Microtrac MT3300EXII) until the dispersion reached a measurable concentration. After ultrasonic dispersion at 30 W for 60 seconds within the analyzer, the particle size at which the cumulative frequency from the smallest particle size side of the particle size distribution measured at 10 seconds reached 50% was defined as the D50 particle size. The refractive index used during measurement was 1.52, and the refractive index of the medium (deionized water) was 1.333. When PPS was used as the thermoplastic resin powder, a 0.5 wt% aqueous solution of polyoxyethylene cumylphenyl ether (trade name Nonal 912A, manufactured by Toho Chemical Industry Co., Ltd.) was used as the dispersion medium.

[0093] (2) Amount of reinforcing filler added The total amount of thermoplastic resin powder and reinforcing filler was set to 100% by weight, and the amount of reinforcing filler added was expressed as weight percent.

[0094] (3) Amount of fluidizing agent added The amount of fluidizing agent added was expressed as a weight percentage, with the total amount of thermoplastic resin powder or thermoplastic resin powder and reinforcing filler being considered as 100% by weight.

[0095] (4) Method for preparing powder composition A predetermined amount of thermoplastic resin powder, reinforcing filler, and flow aid were placed in a poly bag and mixed by hand 500 times. The resulting powder composition was then passed through a test sieve (500 μm opening) manufactured by Tokyo Screen Co., Ltd., as specified in the Japanese Industrial Standard (JIS) JIS Z8801-1 (2006), to prepare a powder composition. The powder composition was passed through the sieve only once.

[0096] (5) Method for measuring the melting point of thermoplastic resin powder contained in a powder composition Using a differential scanning calorimeter (DSCQ20) manufactured by TA Instruments, the peak top of the endothermic peak observed when a powder composition of approximately 5 mg was heated in a nitrogen atmosphere from 30°C at a rate of 20°C / min to a temperature 30°C higher than the end of the melting peak was defined as the melting point of the thermoplastic resin powder contained in the powder composition.

[0097] (6) Powder bed temperature Tb The powder bed temperature was determined by setting the powder surface temperature of the molding tank to Tb using an Aspect Co., Ltd. powder bed fusion fusion system (RaFaElII 150C-HT or RaFaElII 300C-HT).

[0098] (7) Laser irradiation energy amount El The laser irradiation energy El was calculated according to the following formula.

[0099]

number

[0100] Hereinafter, n represents the number of laser scans, Pn is the laser output (W) during the nth laser scan, vn is the laser scanning speed (m / s) during the nth laser scan, ln is the laser scanning interval (m) during the nth laser scan, and h is the layer height (mm). All parameters were calculated using values ​​set in the software of the Aspect Co., Ltd. powder bed fusion fusion system (RaFaElII 150C-HT or RaFaElII 300C-HT).

[0101] (8) Energy required for melting: Em The required energy for melting, Em, was calculated according to the following formula.

[0102]

number

[0103] Note that C: specific heat of the powder composition (J / g·K), Tm: melting point of the thermoplastic resin powder contained in the powder composition (°C), Tb: powder bed temperature (°C), Hf: latent heat of fusion of the powder composition (J / g), and ρb: bulk density of the powder composition (g / mL).

[0104] (9) Specific heat of powder composition C Using a differential scanning calorimeter (DSCQ20) manufactured by TA Instruments, approximately 5 mg of the powder composition was heated under a nitrogen atmosphere from a temperature 80°C below the melting point of the thermoplastic resin powder contained in the powder composition at a rate of 10°C / min down to a temperature 30°C below the melting point. The median of the measured temperatures, i.e., the specific heat C at a temperature 55°C below the melting point, was used to calculate the amount of energy required for melting, Em. In accordance with the Japanese Industrial Standard (JIS) JIS K 7123 (2012), the specific heat of the powder composition can be calculated according to the following formula.

[0105]

number

[0106] Note that H represents the difference in the vertical axis direction of the DSC curves between the empty container and the container containing the standard substance, h represents the difference in the vertical axis direction of the DSC curves between the empty container and the container containing the powder composition, mr represents the mass of the standard substance (mg), m represents the mass of the powder composition (mg), and Cr represents the specific heat of the standard substance (J / g·K). α-alumina was used as the standard substance.

[0107] (10) Latent heat of fusion Hf of the powder composition Using a differential scanning calorimeter (DSCQ20) manufactured by TA Instruments, approximately 5 mg of a powder composition was heated in a nitrogen atmosphere at a rate of 20 °C / min from 30 °C to a temperature 30 °C higher than the end of the melting peak. The latent heat of fusion of the powder composition was calculated by integrating the region of the endothermic peak observed in the DSC curve (from the melting start temperature to the melting end temperature).

[0108] (11) Bulk density ρb of the powder composition The apparent density of thermoplastic resin powder is determined according to the Japanese Industrial Standard (JIS) JIS Z 7365 (1999), by measuring 50g of thermoplastic resin powder from a funnel at 100cm³. 3 The sample was dropped into a graduated cylinder, its volume was read, and the weight of the polymer powder was divided by that volume to obtain the value.

[0109] (12) Bending strength of three-dimensional objects Using a powder bed fusion fusion apparatus (RaFaElII 150C-HT) manufactured by Aspect Co., Ltd., test specimens with a width of 10 mm, a length of 80 mm, and a thickness of 4 mm were fabricated so that the 80 mm length direction was the X direction, the 10 mm length direction was the Y direction, and the 4 mm thickness direction was the Z direction. After drying in a vacuum dryer at 80°C for 24 hours, the bending strength in the X direction was measured using a Tensilon universal tester (TENSIRON TRG-1250) manufactured by A&D Co., Ltd. Three-point bending tests were performed according to JIS K7171 (2016) with a support distance of 64 mm and a test speed of 2 mm / min, and the maximum bending stress was defined as the bending strength of the three-dimensional object. The measurement temperature was room temperature (23°C), the number of measurements was n=5, and the average value was calculated. The bending strength was calculated using the measured width and thickness of the test specimens.

[0110] (13) Charpy impact strength of three-dimensional objects Test specimens were prepared using the same method as in (12), and a Charpy impact test was performed using a 5J hammer with a DG-UB digital impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd., in accordance with JIS K7111-1 (2012), and the impact strength was calculated. The measurement temperature was room temperature (23°C), the number of measurements was n=5, and the average value was calculated. Notching was not performed, and the impact strength was calculated using the measured width and thickness of the test specimens.

[0111] [Manufacturing Example 1] Method for producing thermoplastic resin powder 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. 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.

[0112] 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. 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 polyphenylene sulfide (PPS) resin powder with a D50 particle size of 50 μm.

[0113] [Manufacturing Example 2] Method for producing thermoplastic resin powder 2 Thermoplastic resin powder was prepared using the method described in Example 1 of International Publication No. 2018 / 207728. Specifically, 360 g of ε-caprolactam (reagent grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polyamide monomer, 240 g of polyethylene glycol (grade 1 polyethylene glycol, 6,000, molecular weight 7,700, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymer incompatible with the resulting polyamide, 2.5 g of antioxidant (BASF's "IRGANOX" (registered trademark) 1098), and 50 g of deionized water were added to a 3 L autoclave. After sealing, the autoclave was pressurized to 1 MPa with nitrogen and then depressurized to 0.1 MPa, a process repeated three times. After purging the inside of the container with nitrogen, the pressure was adjusted to 0.1 MPa and the container was sealed. Subsequently, the stirring speed was set to 60 rpm and the temperature was raised to 230°C. At this time, the pressure in the system was 1.4 MPa, and stirring was continued at 60 rpm for 3 hours while maintaining the pressure and temperature. Next, the pressure was released at a rate of 0.02 MPa / min to reduce the internal pressure to 0 MPa. Then, the polymerization temperature was set to 210°C and nitrogen was flowed at a rate of 5 L / min for 2 hours. Finally, the mixture was discharged into a 2000 g water bath to obtain a slurry. After thoroughly homogenizing the slurry by stirring, it was filtered, and 2000 g of water was added to the filtered product and washed at 80°C. After removing the coarse particles that had passed through a 100 μm sieve, the slurry liquid was filtered again to isolate the product, and the filtered product was dried at 80°C for 12 hours to prepare 300 g of polyamide 6 (PA6) powder. The D50 particle size of the obtained PA6 powder was 52 μm.

[0114] [Example 1] A powder composition was prepared by powder mixing 100% by weight of the PPS resin powder from Production Example 1 as the thermoplastic resin powder and 0.15% by weight of trimethylsilylated amorphous silica X-24-9500 (manufactured by Shin-Etsu Chemical Co., Ltd., D50 particle size 170 nm) as a flow aid. The properties of the obtained powder composition were C: 1.3 J / g·K, Tm: 294℃, Hf: 54 J / g, and ρb: 0.62 g / mL. Three-dimensional objects were manufactured using 1.5 kg of the obtained powder composition with a powder bed fusion fusion apparatus (RaFaElII 150C-HT) manufactured by Aspect Co., Ltd. The manufacturing conditions were set to Tb: 260℃, Pn: 19.0 W, vn: 5 m / s, ln: 0.2 mm, h: 0.1 mm, and n: 2. The second laser scan was performed immediately after the first laser scan. The calculated values ​​were Em: 61 J / mL, El: 380 J / mL, and El / Em: 6.2. The resulting 3D printed object had a bending strength of 85 MPa and a Charpy impact strength of 5.9 kJ / m². 2 It exhibited relatively good mechanical properties.

[0115] [Example 2] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Example 1, except that P1: 19.0W and P2: 8.0W were set. The calculated values ​​were Em: 61 J / mL, El: 270 J / mL, and El / Em: 4.4. The resulting three-dimensional object had a bending strength of 84 MPa and a Charpy impact strength of 6.3 kJ / m². 2 It exhibited relatively good mechanical properties.

[0116] [Example 3] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Example 1, except that P1: 19.0W, P2: 7.5W, P3: 7.5W, and n: 3. The calculated values ​​were Em: 61 J / mL, El: 340 J / mL, and El / Em: 5.6. The resulting three-dimensional object exhibited a bending strength of 88 MPa and a Charpy impact strength of 7.0 kJ / m². 2It exhibited relatively good mechanical properties.

[0117] [Example 4] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Example 3, except that P1: 19.0W, P2: 4.0W, and P3: 4.0W were set. The calculated values ​​were Em: 61 J / mL, El: 270 J / mL, and El / Em: 4.4. The resulting three-dimensional object had a bending strength of 85 MPa and a Charpy impact strength of 6.5 kJ / m². 2 It exhibited relatively good mechanical properties.

[0118] [Example 5] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Example 1, except that Tb was set to 240°C. The calculated values ​​were Em: 77 J / mL, El: 380 J / mL, and El / Em: 4.9. The resulting three-dimensional object exhibited a bending strength of 80 MPa and a Charpy impact strength of 6.0 kJ / m². 2 It exhibited relatively good mechanical properties.

[0119] [Example 6] As a thermoplastic resin powder, 60% by weight of the PA6 powder of Production Example 2, 40% by weight of glass fiber EPG40MD-01N (manufactured by Nippon Electric Glass Co., Ltd., fiber length 40 μm), and 0.30% by weight of trimethylsilylated amorphous silica X-24-9500 (manufactured by Shin-Etsu Chemical Co., Ltd., D50 particle size 170 nm) as a flow aid were used to prepare a powder composition by powder mixing. The properties of the obtained powder composition were C: 1.3 J / g·K, Tm: 215 °C, Hf: 42 J / g, ρb: 0.71 g / mL. Using 1.5 kg of the obtained powder composition, a three-dimensional shaped object was manufactured with RaFaElII 150C-HT. The manufacturing conditions were the same as in Example 1 except that Tb was set to 204 °C and Pk was set to 12.0 W. Em: 40 J / mL, El: 240 J / mL, and El / Em: 6.0 were calculated. The flexural strength of the obtained three-dimensional shaped object was 116 MPa, and the Charpy impact strength was 17.7 kJ / m 2 and it showed relatively good mechanical properties.

[0120] [Comparative Example 1] A powder composition was prepared in the same manner as in Example 1. Using 5 kg of the obtained powder composition, a three-dimensional shaped object was manufactured with a powder bed fusion bonding device (RaFaElII 300C-HT) manufactured by Aspect Co., Ltd. The manufacturing conditions were set to Tb: 260 °C, P1: 23.0 W, v1: 10 m / s, l1: 0.2 mm, h: 0.1 mm, and n: 1. Em: 61 J / mL, El: 115 J / mL, and El / Em: 1.9 were calculated. The flexural strength of the obtained three-dimensional shaped object was 75 MPa, and the Charpy impact strength was 2.9 kJ / m 2 and compared with the three-dimensional shaped objects manufactured in Examples 1 to 5, the mechanical properties deteriorated.

[0121] [Comparative Example 2] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional shaped object was manufactured with RaFaElII 150C-HT. The manufacturing conditions were the same as in Example 1 except that n was set to 1. Em: 61 J / mL, El: 190 J / mL, and El / Em: 3.1 were calculated. The flexural strength of the obtained three-dimensional shaped object was 75 MPa, and the Charpy impact strength was 5.0 kJ / m 2As a result, the mechanical properties were worse compared to the three-dimensional molded objects produced in Examples 1-5.

[0122] [Comparative Example 3] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Comparative Example 1, except that Tb was set to 240°C. The calculated values ​​were Em: 77 J / mL, El: 190 J / mL, and El / Em: 2.5. The resulting three-dimensional object exhibited a bending strength of 56 MPa and a Charpy impact strength of 4.0 kJ / m². 2 As a result, the mechanical properties were worse compared to the three-dimensional molded objects produced in Examples 1-5.

[0123] [Comparative Example 4] A powder composition was prepared in the same manner as in Example 1. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using a RaFaElII 150C-HT. The fabrication conditions were the same as in Example 1, except that n was set to 5. The calculated values ​​were Em: 61 J / mL, El: 950 J / mL, and El / Em: 15.6. The resulting three-dimensional object had a bending strength of 70 MPa and a Charpy impact strength of 4.5 kJ / m². 2 As a result, the mechanical properties were worse compared to the three-dimensional molded objects produced in Examples 1-5.

[0124] [Comparative Example 5] A powder composition was prepared in the same manner as in Example 6. Using 1.5 kg of the obtained powder composition, a three-dimensional object was fabricated using RaFaElII 150C-HT. The fabrication conditions were the same as in Example 6, except that n was set to 1. The calculated values ​​were Em: 40 J / mL, El: 120 J / mL, and El / Em: 3.0. The bending strength of the obtained three-dimensional object was 115 MPa and the Charpy impact strength was 13.6 kJ / m2, indicating that the mechanical properties were worse compared to the three-dimensional object fabricated in Example 6.

[0125] [Table 1] [Industrial applicability]

[0126] This invention provides a method for manufacturing three-dimensional objects using a powder bed fusion method, and also provides three-dimensional objects that exhibit high mechanical properties, making them suitable for a wide range of applications in industries such as automotive, aerospace, and robotics. [Explanation of Symbols]

[0127] 1. Tank for forming the molded object 2. Stage of the tank for forming the molded object. 3. A supply tank pre-filled with the resin powder or resin powder composition to be supplied. 4. Stage of a tank pre-filled with the resin powder or resin powder composition to be supplied. 5 Recorder 6. Thermal energy 7 X, Y, Z coordinate system 8 Planar direction for laminating resin powder or resin powder composition 9. Height direction for stacking resin powder or resin powder composition 10 Three-dimensional objects 11 Resin powder or resin powder composition that did not form a molded object P Resin powder or resin powder composition

Claims

1. A method for manufacturing a three-dimensional object by powder bed fusion bonding using a powder composition containing thermoplastic resin powder with a D50 particle size of 1 μm to 100 μm, wherein the three-dimensional object is manufactured under conditions that satisfy the following equation (3), where the laser irradiation energy amount (El) defined by equation (1) and the melting energy amount (Em) defined by equation (2) below. [Math 1] (In the formula, n represents the number of laser scans, n is an integer greater than or equal to 2, Pn is the laser output (W) during the nth laser scan, vn is the laser scanning speed (m / s) during the nth laser scan, ln is the laser scanning interval (m) during the nth laser scan, and h is the stacking height (mm).) 【Number 2】 (In the formula, C is the specific heat of the powder composition (J / g·K), Tm is the melting point of the thermoplastic resin powder contained in the powder composition (°C), Tb is the powder bed temperature (°C), Hf is the latent heat of fusion of the powder composition (J / g), and ρb is the bulk density of the powder composition (g / mL).) [Math 3]

2. A method for manufacturing a three-dimensional object according to claim 1, wherein the laser irradiation energy amount (El) is 900 J / mL or less.

3. A method for manufacturing a three-dimensional object according to claim 1, wherein the laser output Pn is 3W or more and 300W or less.

4. A method for manufacturing a three-dimensional object according to claim 1, wherein the laser scanning speed vn is 1,000 mm / s or more and 30,000 mm / s or less.

5. A method for manufacturing a three-dimensional object according to claim 1, wherein the powder bed temperature Tb is 10°C or more lower than the melting point Tm of the thermoplastic resin powder contained in the powder composition.

6. A method for manufacturing a three-dimensional object according to claim 1, wherein the powder bed temperature Tb is 150°C or higher.

7. The method for producing a three-dimensional molded object according to claim 1, wherein the thermoplastic resin constituting the thermoplastic resin powder is at least one selected from polyphenylene sulfide, polyamide, polyetheretherketone, polypropylene, polyester, polybutylene terephthalate, polyetherimide, polyamideimide, polyethersulfone, polyethylene, polyurethane, and polytetrafluoroethylene.

8. A method for manufacturing a three-dimensional object according to claim 1, wherein the total amount of thermoplastic resin powder and reinforcing filler is 100% by weight, and the reinforcing filler is 1% by weight or more and 50% by weight or less.

9. A three-dimensional object obtained by any of the manufacturing methods described in claims 1 to 8.

Images