Resin powder for 3D printer, method for producing article, and article

Abstract

Provided is a technology related to resin particles for a 3D printer, said resin particles being capable of improving the surface properties and strength of an article obtained using a 3D printer.　A resin powder for a three-dimensional printer according to an embodiment of the present invention contains first resin particles, second resin particles, and third resin particles. The first resin particles are formed from a polyamide resin having a weight average molecular weight of 30,000 to 80,000, and include the alpha phase as a crystal phase. The second resin particles are formed from a polyamide resin having a weight average molecular weight of 30,000 to 80,000, wherein the crystal phase comprises only the gamma phase. The third resin particles are formed from a polyamide resin having a weight average molecular weight of 20,000 to 30,000, wherein the crystal phase comprises only the gamma phase. The content of the first resin particles is 65-85 mass%. The content of the second resin particles is 5-15 mass%. The content of the third resin particles is 3-15 mass%.

Description

Resin powder for 3D printers, manufacturing method for molded products, and molded products

[0001] The present invention relates to a resin powder for a three-dimensional printer, a method for manufacturing a shaped product, and a shaped product.

[0002] Three-dimensional printers, which create three-dimensional objects using additive manufacturing technology based on three-dimensional digital data, are expected to be put to practical use in a variety of fields. One method for manufacturing three-dimensional objects using a three-dimensional printer is the additive manufacturing method using powder sintering.

[0003] Resin particles made of a semi-aromatic polyamide resin composition are known as resin particles used in the powder sintering lamination method (see, for example, Patent Document 1).

[0004] WO2015 / 159834 publication

[0005] Three-dimensional objects obtained by three-dimensional printers using conventional resin particles have room for improvement in that they are prone to surface defects known as orange peel, such as rough surfaces, voids, or distortions, and that the strength of the three-dimensional objects is insufficient.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide technology related to resin particles for three-dimensional printers that can improve the surface properties and strength of objects produced by three-dimensional printers.

[0007] One aspect of the present invention is a resin powder for a three-dimensional printer, the resin powder containing first, second, and third resin particles, wherein the first resin particles are made of a polyamide-based resin having a weight-average molecular weight of 30,000 or more and 80,000 or less and contain an α-phase as a crystalline phase, the second resin particles are made of a polyamide-based resin having a weight-average molecular weight of 30,000 or more and 80,000 or less and contain only a γ-phase as a crystalline phase, and the third resin particles are made of a polyamide-based resin having a weight-average molecular weight of 20,000 or more and less than 30,000 and contain only a γ-phase as a crystalline phase, the first resin particles are contained in an amount of 65 to 85% by mass, the second resin particles are contained in an amount of 5 to 15% by mass, and the third resin particles are contained in an amount of 3 to 15% by mass.

[0008] In the resin powder for a 3D printer of the above aspect, the first resin particles may have a crystallinity of 65 to 80%, and the second resin particles may have a crystallinity of 70 to 85%, with the crystallinity of the first resin particles being lower than that of the second resin particles. The third resin particles may be coated with a solid lubricant. The solid lubricant may include one or more selected from the group consisting of silicon oxide, titanium oxide, zinc oxide, aluminum oxide, fluororesin, acrylic resin, styrene resin, silicone resin, urethane resin, polyethylene resin, polypropylene resin, metal stearates, metal laurates, metal ricinoleates, and metal octylates. The coverage of the third resin particles with the solid lubricant may be 3 to 80%. The first resin particles may have an average particle size of 10 to 120 μm. The second resin particles may have an average particle size of 10 to 120 μm. The third resin particles may have an average particle size of 10 to 120 μm.

[0009] Another aspect of the present invention is a method for manufacturing a shaped product, the method including the step of manufacturing a shaped product by powder sintering layered manufacturing using the resin powder for a three-dimensional printer according to any one of the above aspects.

[0010] Yet another aspect of the present invention is a shaped article obtained by using the shaped article manufacturing method of the above-mentioned aspect.

[0011] According to the present invention, it is possible to provide a technology relating to resin particles for three-dimensional printers that can improve the surface properties and strength of objects obtained by three-dimensional printers.

[0012] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expression "a to b" in the description of a range of values ​​means that the range is from a to b, unless otherwise specified.

[0013] (Resin Powder for Three-Dimensional Printers) The resin powder for three-dimensional printers according to the embodiment contains first resin particles, second resin particles, and third resin particles.

[0014] <First Resin Particles> The first resin particles are formed of a polyamide resin having a weight-average molecular weight of 30,000 or more and 80,000 or less. By setting the lower limit of the weight-average molecular weight to the above value, the tensile strength of a three-dimensional object (hereinafter sometimes referred to as the "obtained object" or simply the "object") obtained using the resin particles for a 3D printer according to the embodiment can be increased. By setting the upper limit of the weight-average molecular weight to the above value, the resin as a whole can be more easily melted, thereby suppressing the formation of surface defects in the object.

[0015] The first resin particles contain an α-phase (α-type crystalline phase) as a crystalline phase.

[0016] Examples of polyamide resins used for the first resin particles include nylon 12, nylon 66, nylon 6, and nylon 11.

[0017] The content of the first resin particles relative to the total amount of resin particles for a three-dimensional printer is preferably 65 to 85% by mass. By setting the lower limit of the content to this value, the tensile strength of the molded object can be increased. By setting the upper limit of the content to this value, a decrease in the tensile strength of the molded object can be suppressed.

[0018] The crystallinity of the first resin particles is preferably 65 to 80%. However, the crystallinity of the first resin particles is preferably lower than the crystallinity of the second resin particles described below. By setting the lower limit of the crystallinity to the above value, the tensile strength of the shaped product can be increased. By setting the upper limit of the crystallinity to the above value, the formation of surface defects in the shaped product can be suppressed. The crystallinity of the first resin particles is calculated using X-ray diffraction (XRD) according to the following formula: Crystallinity (%) = 100 x (crystal peak value of α phase + crystal peak value of γ phase) / (crystal peak value of α phase + crystal peak value of γ phase + peak value of amorphous phase)

[0019] The average particle size of the first resin particles is preferably 10 to 120 μm. By setting the lower limit of the average particle size within the above range, the fluidity of the particles is improved, and the formation of surface defects in the molded product can be suppressed. By setting the upper limit of the average particle size within the above range, the formation of surface defects in the molded product can be suppressed. The average particle size of the first resin particles (as well as the second and third resin particles described below) can be measured using a laser diffraction particle size analyzer (Malvern Instruments, Mastersizer 3000, wet dispersion unit Hydro MV).

[0020] The circularity of the first resin particles is preferably 0.75 to 1.00. By setting the lower limit of the circularity to this value, the fluidity of the particles is increased, making it possible to uniformly pack the particles in the powder-laying step of three-dimensional printer modeling, and suppressing the formation of surface defects in the modeled object. By setting the upper limit of the circularity to this value, the shape of the first resin particles becomes closer to a perfect sphere, improving the packing properties of the first resin particles and suppressing the formation of surface defects in the modeled object.

[0021] <Second Resin Particles> The second resin particles are formed of a polyamide resin having a weight-average molecular weight of 30,000 or more and 80,000 or less. By setting the lower limit of the weight-average molecular weight to the above value, the tensile strength of the shaped object can be increased. By setting the upper limit of the weight-average molecular weight to the above value, the formation of surface defects in the shaped object can be suppressed.

[0022] The second resin particles are composed of only a γ-phase (γ-type crystalline phase) as a crystalline phase.

[0023] Examples of polyamide resins used for the second resin particles include nylon 12, nylon 66, nylon 6, and nylon 11.

[0024] The content of the second resin particles relative to the total resin particles for a 3D printer is preferably 5 to 15% by mass. By setting the lower limit of the content to this value, the entire resin becomes more easily dissolved during modeling, reducing surface defects in the modeled object. By setting the upper limit of the content to this value, the tensile strength of the modeled object can be increased.

[0025] The crystallinity of the second resin particles is preferably 70 to 85%. By setting the lower limit of the crystallinity to the above value, the tensile strength of the shaped product can be increased. By setting the upper limit of the crystallinity to the above value, the formation of surface defects in the shaped product can be suppressed. The crystallinity of the second resin particles is calculated using X-ray diffraction (XRD) according to the following formula: Crystallinity (%) = 100 x (crystal peak value of α phase + crystal peak value of γ phase) / (crystal peak value of α phase + crystal peak value of γ phase + peak value of amorphous phase)

[0026] The average particle size of the second resin particles is preferably 10 to 120 μm. By setting the lower limit of the average particle size within the above range, the fluidity of the particles can be improved and the formation of surface defects in the molded product can be suppressed. By setting the upper limit of the average particle size within the above range, the formation of surface defects in the molded product can be suppressed.

[0027] The circularity of the second resin particles is preferably 0.75 to 1.00. By setting the lower limit of the circularity to this value, the fluidity of the particles is increased, making it possible to uniformly pack the particles in the powder-laying step of three-dimensional printer modeling, and suppressing the formation of surface defects in the modeled object. By setting the upper limit of the circularity to this value, the shape of the second resin particles becomes closer to a perfect sphere, improving the packing properties of the second resin particles and suppressing the formation of surface defects in the modeled object.

[0028] <Third Resin Particles> The third resin particles are formed of a polyamide resin having a weight-average molecular weight of 20,000 or more but less than 30,000. By setting the lower limit of the weight-average molecular weight to the above value, the stickiness of the molten resin particles is maintained appropriately during the powder-laying process of 3D printer modeling, enabling uniform particle packing, reducing the occurrence of lattice defects in the modeled object and ultimately increasing tensile strength. By setting the upper limit of the weight-average molecular weight to the above value, the particles are more likely to melt during 3D printer modeling, promoting interparticle bonding and increasing the tensile strength of the modeled object.

[0029] The third resin particles have a crystal phase consisting solely of a γ phase (γ-type crystal phase).

[0030] Examples of polyamide resins used for the third resin particles include nylon 12, nylon 66, nylon 6, and nylon 11.

[0031] The content of the third resin particles relative to the total resin particles for a three-dimensional printer is preferably 3 to 15% by mass. By setting the lower limit of the content to the above value, the tensile strength of the molded object can be increased. By setting the upper limit of the content to the above value, a decrease in the tensile strength of the molded object can be suppressed.

[0032] The third resin particles are preferably coated with a solid lubricant. The solid lubricant preferably contains one or more selected from the group consisting of silicon oxide, titanium oxide, zinc oxide, aluminum oxide, fluororesin, acrylic resin, styrene resin, silicone resin, urethane resin, polyethylene resin, polypropylene resin, metal stearates, metal laurates, metal ricinoleates, and metal octylates. This improves the fluidity of the third resin particles, enabling dense packing of the third resin particles in the powder-laying step of 3D printer modeling, thereby reducing the occurrence of lattice defects in the modeled object and increasing its strength.

[0033] The coverage of the surfaces of the third resin particles with the solid lubricant is preferably 3 to 80%. By setting the lower limit of the coverage to this value, a spacer effect occurs between the particles, reducing particle aggregation and ultimately suppressing the formation of surface defects in the molded product. By setting the upper limit of the coverage to this value, interparticle bonding is promoted, suppressing the formation of surface defects in the molded product and maintaining tensile strength.

[0034] The average particle size of the third resin particles is preferably 10 to 120 μm. By setting the lower limit of the average particle size within the above range, the fluidity of the particles can be improved and the formation of surface defects in the molded product can be suppressed. By setting the upper limit of the average particle size within the above range, the formation of surface defects in the molded product can be suppressed.

[0035] The circularity of the third resin particles is preferably 0.75 to 1.00. By setting the lower limit of the circularity to this value, the fluidity of the particles is increased, making it possible to uniformly pack the particles in the powder-laying step of three-dimensional printer modeling, and suppressing the formation of surface defects in the modeled object. By setting the upper limit of the circularity to this value, the shape of the third resin particles becomes closer to a perfect sphere, improving the packing properties of the third resin particles and suppressing the formation of surface defects in the modeled object.

[0036] The polyamide resin constituting the third resin particles is a gamma phase with a smaller molecular weight, or in other words, a shorter molecular chain, than the first and second resin particles. Therefore, when the resin powder for 3D printers is melted, the polyamide resin constituting the third resin particles undergoes vigorous molecular movement and can penetrate into the first resin particles. This prevents the formation of an alpha phase in the first resin particles due to shrinkage.

[0037] The resin powder for 3D printers described above reduces the occurrence of incomplete melting in the resulting molded product, reduces the formation of rough surfaces and voids, and improves strength. Furthermore, because the resin shrinkage during cooling is reduced, the resulting molded product has improved dimensional stability and is less likely to warp. This in turn reduces the occurrence of surface defects known as orange peel, such as rough surfaces, voids, or warping, as well as a decrease in tensile strength.

[0038] (Method for producing resin particles) An example of a method for producing the first to third resin particles will be described. The first resin particles and the second resin particles can be formed through the following mixing, kneading, pulverizing, classifying, and spheronizing steps. The third resin particles can be formed through the above-mentioned steps plus an external addition step.

[0039] <Mixing step> i) Weigh the raw material powder ii) Place the weighed raw materials into a 20 L Henschel mixer (FM20 manufactured by Nippon Coke) and mix.

[0040] <Kneading step> i) The stirred powder is heated to 160 to 250°C in a twin-screw kneader (for example, PCM-30 manufactured by Ikegai) and melt-kneaded. ii) The molten kneaded product discharged from the twin-screw kneader is passed through cooled reduction rolls, and the plate-shaped solid kneaded product is water-cooled.

[0041] <Pulverization step> i) The water-cooled plate-like solid kneaded product is pulverized in a mill-type pulverizer to obtain a coarsely pulverized product of 1.0 mm or less, ii) The coarsely pulverized product is finely pulverized in a jet mill (for example, ULTRA SONIC JET MILL I-2, manufactured by Nippon Pneumatic Co., Ltd.) to obtain a finely pulverized product with a volume-based average particle size of 10 to 120 μm.

[0042] <Classification Step> Particles of 10 μm or less are removed from the finely pulverized material using an air classifier (for example, DS2UR manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain a classified powder.

[0043] <Spheronization Step> The classified powder is treated in a hot air spheronizing device (for example, Meteor Rainbow MR, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) heated to 400°C to obtain a spheronized product.

[0044] <External Addition Step> i) Weigh out 0.1 to 2.0 mass % of a solid lubricant based on the mass of the spheroidized material. ii) Place the spheroidized material and the solid lubricant in a 10 L Henschel mixer (for example, FM10 manufactured by Nippon Coke) and mix by stirring.

[0045] (Method for manufacturing a molded product) The resin particles for 3D printers according to the embodiment are suitable for use in producing a three-dimensional molded product by the powder sintering lamination method, which includes the following steps: <Powder spreading step> Using a mechanism such as a wiper, the resin particles for 3D printers stored in a tank are moved onto the stage of the printer, and a thin layer of the resin particles for 3D printers is formed on the stage. <Laser irradiation step> The resin particles for 3D printers on the stage are irradiated with laser light in accordance with the 3D data of the molded product, causing the resin particles for 3D printers to melt and sinter together. <Lamination step> After the stage is lowered by one layer, the step of forming a thin layer of the resin particles for 3D printers and the laser irradiation step are sequentially repeated, similar to the powder spreading step, to obtain the desired molded product.

[0046] <Shaped Product> The shaped product according to the embodiment is obtained by the above-described shaped product manufacturing method.

[0047] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0048] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0049] According to the above-mentioned method for producing resin particles, the first to third resin particles were prepared, and resin powders for three-dimensional printers were produced using the blending amounts of each component shown in Table 1.

[0050] <Surface properties of the molded object> Using each resin powder for 3D printers, a strip-shaped test piece was prepared in accordance with JIS K7139 using a powder bed fusion 3D printer (RaFaEl II 150C-HT) manufactured by Aspect Co., Ltd. The following items were evaluated for the surface of the obtained test piece: Rough surface: Graininess remains visually: 1 point, none remains: 5 points Holes: Holes are visually observed: 1 point, none are observed: 5 points Distortion: The surface is not straight and there is distortion: 1 point, there is no distortion: 5 points The total score for the above three items was calculated and evaluated according to the following criteria: ◎: 15 points or more 〇: 11 to 14 points △: 7 to 10 points ×: 3 to 6 points

[0051] <Tensile strength of molded object> Using each resin powder for 3D printers, strip-shaped test pieces were produced in accordance with JIS K7139 using a powder bed fusion 3D printer (RaFaEl II 150C-HT) manufactured by Aspect Corporation. The tensile strength (unit: MPa) of the test pieces was measured in accordance with JIS K7161-1 at a temperature of 23°C and a tensile speed of 5 mm / min. The obtained tensile strength was evaluated according to the following criteria: ◎: 40 MPa or more ◯: 35 to less than 40 MPa △: 30 to less than 35 MPa ×: Less than 30 MPa

[0052]

[0053]

[0054]

[0055]

[0056] By using the resin particles for three-dimensional printers of the present invention as a printing material for a three-dimensional printer, a three-dimensional object having excellent surface properties and strength can be obtained. CROSS-REFERENCE TO RELATED APPLICATIONS

[0057] This application claims priority based on Japanese Patent Application No. 2024-013559, filed with the Japan Patent Office on January 31, 2024, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A resin powder for a 3D printer comprising first resin particles, second resin particles, and third resin particles, wherein the first resin particles are formed of a polyamide resin having a weight-average molecular weight of 30,000 or more and 80,000 or less, and include an α-phase as a crystalline phase, the second resin particles are formed of a polyamide resin having a weight-average molecular weight of 30,000 or more and 80,000 or less, and the crystalline phase consists solely of a γ-phase, the third resin particles are formed of a polyamide resin having a weight-average molecular weight of 20,000 or more and less than 30,000, and the crystalline phase consists solely of a γ-phase, the content of the first resin particles is 65 to 85% by mass, the content of the second resin particles is 5 to 15% by mass, and the content of the third resin particles is 3 to 15% by mass.

2. The resin powder for a 3D printer according to claim 1, wherein the first resin particles have a crystallinity of 65 to 80%, the second resin particles have a crystallinity of 70 to 85%, and the crystallinity of the first resin particles is lower than the crystallinity of the second resin particles.

3. The resin powder for a three-dimensional printer according to claim 1, wherein the third resin particles are coated with a solid lubricant.

4. The resin powder for a three-dimensional printer according to claim 3, wherein the solid lubricant comprises one or more selected from the group consisting of silicon oxide, titanium oxide, zinc oxide, aluminum oxide, fluororesin, acrylic resin, styrene resin, silicone resin, urethane resin, polyethylene resin, polypropylene resin, metal stearates, metal laurates, metal ricinoleates, and metal octylates.

5. The resin powder for a three-dimensional printer according to claim 3, wherein the coverage of the third resin particles with the solid lubricant is 3 to 80%.

6. The resin powder for a three-dimensional printer according to claim 1, wherein the first resin particles have an average particle size of 10 to 120 μm.

7. The resin powder for a three-dimensional printer according to claim 1, wherein the second resin particles have an average particle size of 10 to 120 μm.

8. The resin powder for a three-dimensional printer according to claim 1, wherein the third resin particles have an average particle size of 10 to 120 μm.

9. A method for manufacturing a shaped product, comprising the step of manufacturing a shaped product by powder sintering layered manufacturing using the resin powder for a 3D printer according to any one of claims 1 to 8.

10. A shaped product obtained by using the shaped product manufacturing method according to claim 9.

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