CN115028971A - Resin powder for producing three-dimensional object and method for producing three-dimensional object - Google Patents

Abstract

The invention discloses a resin powder for manufacturing a three-dimensional object and a three-dimensional object manufacturing method. The resin powder for producing a three-dimensional object has a number average equivalent circle diameter of 10 micrometers or more but 150 micrometers or less, and the resin powder has a median value of particle size distribution based on the equivalent circle diameter higher than the average equivalent circle diameter, and a loose-fill ratio of 40.4% or more. The three-dimensional object manufacturing method comprises the following steps: forming a layer containing the resin powder for producing a three-dimensional object; and bonding particles of a resin powder for producing a three-dimensional object in selected regions of the layer to each other, wherein the method of producing a three-dimensional object repeats the forming and bonding.

Description

Resin powder for producing three-dimensional object and method for producing three-dimensional object

The present application is a divisional application of an invention patent application entitled "resin powder for producing three-dimensional object, three-dimensional object production method, and three-dimensional object production apparatus", having an application date of 2018, 3 and 7, and an application number of 201880019309.1, which is filed by shin from shin-chan corporation.

Technical Field

The present invention relates to a resin powder for producing a three-dimensional object, a three-dimensional object producing method, and a three-dimensional object producing apparatus.

Background

The powder laminate manufacturing method is a method of curing a layer of a powdery material layer by layer with a laser or an adhesive to manufacture an object.

The method using a laser is called a Powder Bed Fusion (PBF) method. As the PBF method, a Selective Laser Sintering (SLS) method of forming a three-dimensional object by selective laser irradiation, and a Selective Mask Sintering (SMS) method of performing planar laser irradiation using a mask are known. On the other hand, as a method of using a binder, a binder jetting method of discharging an ink containing a binder resin by a method such as ink jet to form a three-dimensional object is known.

Among these methods, the PBF method selectively irradiates a thin layer of metal, ceramic, or resin with a laser beam to fuse and bond powder particles to each other to form a film, forms another layer on the formed film, and repeats the same operation to sequentially laminate the layers. In this way, the method can obtain a three-dimensional object (for example, see patent documents 1 to 4).

In the case of using resin powder in the PBF method, the internal stress between thin layers is kept low or relaxed, the resin powder layer supplied in the supply tank is heated to a temperature near the softening point of the resin, and selectively irradiated with a laser beam, so that the irradiated resin powder particles are heated to a temperature higher than or equal to the softening point and fused with each other to make a three-dimensional object.

Currently, polyamide resins are commonly used in the PBF process. In particular, polyamide 12 is suitably used because polyamide 12 has a relatively low melting point among polyamides and has a low heat shrinkage factor and low water absorption.

In recent years, demands for use of three-dimensional objects have been increasing, and demands for use of various resins have been raised not only as prototypes but also as end products.

List of cited documents

Patent document

Patent document 1

Japanese unexamined patent application publication No.2015-180538

Patent document 2

PCT International publication No. JP-T-2014-522331 for Japanese translation

Patent document 3

PCT International publication No. JP-T-2013-529599 for Japanese translation

Patent document 4

PCT International publication No. JP-T-2015-

Disclosure of Invention

Technical problem

An object of the present disclosure is to provide a resin powder for producing a three-dimensional object, which is capable of providing a three-dimensional object to be obtained having excellent density, excellent dimensional stability, and excellent surface characteristics without lowering strength even if the resin powder has been stored in a high humidity environment.

Technical scheme for solving problems

According to one aspect of the present disclosure, the resin powder for making a three-dimensional object has a number average equivalent circle diameter of 10 micrometers or more but 150 micrometers or less. The median value of the particle size distribution of the resin powder based on the equivalent circle diameter is higher than the average equivalent circle diameter.

The invention has the advantages of

The present disclosure provides a resin powder for producing a three-dimensional object, which is capable of providing a three-dimensional object to be obtained having excellent density, excellent dimensional stability, and excellent surface characteristics without a decrease in strength even if the resin powder has been stored in a high-humidity environment.

Drawings

Fig. 1 is an exemplary diagram showing an example of an approximately columnar body;

FIG. 2 is a schematic diagram illustrating an example of a three-dimensional object fabrication apparatus for use in the three-dimensional object fabrication method of the present disclosure;

fig. 3A is a schematic view showing an example of a step of forming a powder layer having a smooth surface;

fig. 3B is a schematic view showing an example of a step of forming a powder layer having a smooth surface;

fig. 3C is a schematic view showing an example of a step of dropping a liquid material for creating a three-dimensional object;

fig. 3D is a schematic view showing an example of a step of newly forming a resin powder layer in the formation-side powder storage tank;

fig. 3E is a schematic view showing an example of a step of newly forming a resin powder layer in the formation-side powder storage tank;

fig. 3F is a schematic view showing an example of a step of dropping again the liquid material for producing the three-dimensional object;

FIG. 4 is a graph showing the distribution of equivalent circle diameters of resin powders used to make the three-dimensional object of example 1;

FIG. 5 is a diagram showing the distribution of equivalent circle diameters of resin powders for producing the three-dimensional object of comparative example 1;

fig. 6 is a diagram showing the distribution of the equivalent circle diameters of the resin powder for producing the three-dimensional object of comparative example 2.

Detailed Description

(resin powder for producing three-dimensional object)

The resin powder used to make the three-dimensional objects of the present disclosure has a number average equivalent circle diameter of 10 microns or more but 150 microns or less. The median value of the particle size distribution of the resin powder based on the equivalent circle diameter is higher than the average equivalent circle diameter. The resin powder preferably contains a thermoplastic resin and, if necessary, other components.

The resin powder used to make the three-dimensional objects of the present disclosure is based on the following findings: the existing resin powder for producing a three-dimensional object is affected by humidity in a storage environment, thereby reducing the strength of the three-dimensional object to be obtained.

Fine powders have a large specific surface area per unit volume. Thus, fine powder has larger contact points and larger inter-particle contact areas than coarse powder. In a high-temperature and high-humidity environment, liquid bridging force of water acts on contact points between particles and reduces the flowability of the powder. Here, the flowability of the fine powder is significantly reduced because the contact points and the contact area between the particles of the fine powder are large. The reduction in flowability is expressed as a reduction in the bulk density of the powder. The reduction in bulk density of the powder results in a reduction in density and a reduction in strength of the object produced in the object-making apparatus. In contrast, the resin powder for producing a three-dimensional object of the present disclosure is suppressed from being affected by the liquid bridging force of water at the contact point between particles, and the powder flowability under a high-temperature and high-humidity environment is prevented from deteriorating. This makes it possible to suppress a decrease in the bulk density of the resin powder used to fabricate the three-dimensional object, thereby improving the density and strength of the fabricated object.

< average equivalent circle diameter >

The average equivalent circle diameter on the base (i.e., the average of the particle size distribution based on the equivalent circle diameter) is 10 micrometers or more but 150 micrometers or less, preferably 20 micrometers or more but 90 micrometers or less, more preferably 35 micrometers or more but 60 micrometers or less. When the average equivalent circle diameter is 10 micrometers or more but 150 micrometers or less, the resin powder can provide a three-dimensional object to be obtained having excellent density, excellent dimensional stability, and excellent surface characteristics even when stored in a high-humidity environment, while preventing a decrease in strength. The average equivalent circle diameter can be measured, for example, with a particle image analysis apparatus (apparatus name: FPIA3000, available from Spectris).

The equivalent circle diameter can be calculated according to the following formula.

[ mathematical formula 1]

The equivalent circle diameter is calculated based on the projection of each individual particle. The average (number-basis) of the calculated equivalent circle diameters may be calculated as the average equivalent circle diameter.

< median value of particle size distribution based on equivalent circle diameter and average value of particle size distribution based on equivalent circle diameter >

The resin powder used for making a three-dimensional object is a powder containing little minute mixture, and the particle diameter of the main constituent particles is in the range of 30 micrometers or more but 90 micrometers or less, and has an average value in this range.

The median value of the particle size distribution based on the equivalent circle diameter is preferably higher than the average equivalent circle diameter (i.e., the average value in the particle size distribution based on the equivalent circle diameter). When the median value is higher than the average equivalent circle diameter, the resin powder can provide a three-dimensional object having excellent density, excellent dimensional stability, and excellent surface characteristics while preventing the resin from being reduced in strength even if the resin powder has been stored in a high-humidity environment.

In the particle size distribution based on the equivalent circle diameter, when the mountain portion formed by the concentrated distribution of the particle diameters has a wide basal range, the median exists at a position close to the mountain portion, and the average equivalent circle diameter exists at a position far from the median, because the average equivalent circle diameter is greatly affected by the basal. That is, when the median is higher than the average equivalent circle diameter, it indicates that the mountain portion formed by the concentrated distribution of the diameters of the main particles exists at a high position, and the mountain portion is not formed of fine particles. On the other hand, when the median is lower than the average equivalent circle diameter, it indicates that the main mountain portion is formed of fine particles. This provides an indicator of which of the fine particles and the resin powder particles is predominant in the number distribution. In order to obtain a median value of the particle size distribution based on the equivalent circular diameter, when the number of powder particles was counted as 3,000 or more, an image of the particle shape was obtained with a wet flow type particle diameter/shape analyzer (equipment name: FPIA-3000, available from Sysmex Corporation). The equivalent circle diameter of particles having a particle diameter of 0.5 μm or more but 200 μm or less was measured to obtain a particle size distribution. The median value can be calculated from the particle size distribution.

< average circularity >

The average circularity is preferably 0.75 or more but 0.90 or less, more preferably 0.75 or more but 0.85 or less. When the average circularity is 0.75 or more but 0.90 or less, the resin powder can provide a three-dimensional object having excellent density, excellent dimensional stability, and excellent surface characteristics while preventing strength from being reduced even if the resin powder has been stored in a high humidity environment.

Circularity is an indicator of the proximity of a circle. A circularity of 1 indicates the closest degree to the circle. The circularity is obtained according to the following formula, where S represents the area (number of pixels) and L represents the circumference.

[ mathematical formula 2]

Circularity 4 pi S/L ²

In order to obtain the average circularity, the circularity of the resin powder used to produce the three-dimensional object may be measured, and the arithmetic average of the measured circularities may be used as the average circularity.

A simple method for quantifying circularity is to measure circularity using, for example, a wet flow type particle diameter/shape analyzer (equipment name: FPIA-3000, available from Sysmex Corporation). The wet flow type particle diameter/shape analyzer can capture an image of particles in a suspension flowing in a glass cell at a high speed using a CCD and analyze the respective particle images in real time. Such an apparatus that captures an image of the particles and performs image analysis is effective for obtaining the average circularity of the present disclosure. The number of particles to be measured is not particularly limited, and is preferably 1,000 or more, more preferably 3,000 or more.

< Loose filling ratio >

The loose-fill ratio is a value obtained by dividing a bulk density measured with a bulk densitometer (compliant with JIS Z-2504, available from Kuramochi Scientific Instruments) by a true density of the resin.

The loose-fill ratio is preferably 20% or more but 50% or less, more preferably 30% or more but 30% or less. The loose-packing ratio can be obtained by measuring the loose density with a bulk density meter (in conformity with JIS Z-2504, available from Kuramochi Scientific Instruments) and dividing the obtained loose density by the true density of the resin.

The resin powder used for making the three-dimensional object is preferably formed of columnar particles.

The columnar particles are not particularly limited and may be appropriately selected according to the purpose. The pillar length is preferably 10 micrometers or more but 150 micrometers or less, and the pillar diameter is preferably 10 micrometers or more but 150 micrometers or less.

< thermoplastic resin >

The thermoplastic resin means a resin that is plasticized and melted when heated.

Examples of the thermoplastic resin include crystalline resins. The crystalline resin means a resin having a melting peak when measured according to ISO 3146 (plastic transition temperature measuring method, JIS K7121).

The crystalline resin is not particularly limited and may be appropriately selected according to the purpose. Examples of the crystalline resin include polymers such as polyolefin, polyamide, polyester, polyether, polyphenylene sulfide, Liquid Crystal Polymer (LCP), Polyacetal (POM), polyimide, and fluorine resin. One of these crystalline resins may be used alone, or two or more of these crystalline resins may be used in combination.

Examples of polyolefins include polyethylene and polypropylene. One of these polyolefins may be used alone, or two or more of these polyolefins may be used in combination.

Examples of polyamides include: polyamide 410(PA410), polyamide 6(PA6), polyamide 66(PA66), polyamide 610(PA610), polyamide 612(PA612), polyamide 11(PA11), and polyamide 12(PA 12); and semi-aromatic polyamide 4T (PA4T), polyamide MXD6(PAMXD6), polyamide 6T (PA6T), polyamide 9T (PA9T) and polyamide 10T (PA 10T). One of these polyamides may be used alone, or two or more of these polyamides may be used in combination.

Of these polyamides, PA9T, also known as poly (p-phenylene terephthalamide), is formed from diamine containing 9 carbon atoms and terephthalic acid monomers, and is referred to as semi-aromatic because the carboxylic acid side is generally aromatic. In addition, so-called aromatic polyamides, which are formed from p-phenylenediamine and terephthalic acid monomers and are all aromatic series that are also aromatic on the diamine side, are also included in the polyamides of the present disclosure.

Examples of the polyester include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polylactic acid (PLA). Polyesters containing aromatic series, which partially contain terephthalic acid or isophthalic acid to have heat resistance, may also be suitable for use in the present disclosure.

Examples of polyethers include Polyetheretherketone (PEEK), Polyetherketone (PEK), Polyetherketoneketone (PEKK), Polyaryletherketone (PAEK), Polyetheretherketoneketone (PEEKK), and Polyetherketoneetherketoneketone (PEKEKK).

Any other crystalline polymer other than polyethers may also be used. Examples of other crystalline polymers include polyacetals, polyimides, and polyethersulfones. Polymers with 2 melting points, such as PA9T (resin temperature needs to be raised above or equal to the second melting point peak to completely melt the resin) may also be used.

The resin powder for fabricating a three-dimensional object may further contain additives such as resin powders formed of a non-crystalline resin, a toughening agent, a flame retardant, a plasticizer, a stabilizer, an antioxidant, and a nucleating agent, in addition to the thermoplastic resin. One of these additives may be used alone, or two or more of these additives may be used in combination. These additives may be mixed with the thermoplastic resin and contained in the resin powder to produce a three-dimensional object, or may be attached on the surface of the resin powder to produce a three-dimensional object.

Toughening agents are added to primarily increase strength and are added as fillers or fillers. Examples of toughening agents include glass fillers, glass beads, carbon fibers, aluminum spheres, and toughening agents described in international publication No. WO 2008/057844. One of these toughening agents may be used alone, or two or more of these toughening agents may be used in combination. The toughening agent may be included in the resin. The resin powder of the present disclosure is preferably in a suitably dried state. The resin powder may be dried using a vacuum drier or by adding silica gel before use.

Examples of the antioxidant include hydrazide type and amide type, which are metal deactivators; phenol type (hindered phenol type) and amine type, which are radical scavengers; phosphate type and sulfur type, which are peroxide decomposers; and triazine types, which are ultraviolet absorbers. One of these antioxidants may be used alone, or two or more of these antioxidants may be used in combination. In particular, it is known that the combined use of a radical scavenger and a peroxide decomposer is effective. This combination is also particularly effective in this disclosure.

The content of the antioxidant is preferably 0.05% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, and particularly preferably 0.2% by mass or more and 2% by mass or less, with respect to the total amount of the resin powder for making the three-dimensional object. When the content of the antioxidant is within the above range, an effect of preventing thermal degradation can be obtained. This makes it possible to reuse the resin powder used for making the three-dimensional object for object making. Further, an effect of preventing the thermochromic color can also be obtained.

The resin powder used for making the three-dimensional object is preferably a resin having a melting point of 100 ℃ or higher measured according to ISO 3146. It is preferable that the melting point of the resin powder measured according to ISO 3146 is 100 ℃ or higher because the melting point falls within a heat-resistant temperature range in which the resin powder can be used, for example, outside the product. The melting point can be used by Differential Scanning Calorimetry (DSC) according to ISO 3146 (plastic transition temperature measurement method, JIS K7121). When multiple melting points are present, the highest melting point is used.

As the crystalline resin, a crystalline thermoplastic resin with controlled crystallinity is preferable. The crystalline thermoplastic resin can be obtained by hitherto known external stimulation methods such as heat treatment, stretching, nucleating agent and ultrasonic wave treatment. Crystalline thermoplastic resins having controlled crystal size and controlled crystal orientation are more preferred because such crystalline thermoplastic resins can reduce errors that may occur during high temperature recoating.

The method for producing the crystalline thermoplastic resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the method include an annealing treatment for heating the powder at a temperature higher than or equal to the glass transition temperature of each resin to increase the crystallinity, and a method of adding a nucleating agent to further increase the crystallinity and then performing the annealing treatment. Further examples include a method of increasing crystallinity by ultrasonic treatment or by dissolving in a solvent and then slowly volatilizing the solvent, a method of growing crystals by treatment with application of an external electric field, and a method of further stretching a resin to increase orientation and crystallinity and then subjecting the resultant to mechanical processing such as pulverization and cutting.

The annealing treatment can be performed by, for example, heating the resin at a temperature 50 ℃ higher than the glass transition temperature for 3 days, and then slowly cooling the resin to room temperature.

Drawing is a method of drawing a resin melt to have a fiber form with an extruder while stirring the resin melt at a temperature higher than the melting point by 30 ℃ or more, for example. Specifically, the melt is drawn to a size of about 1 time or more but 10 times or less to have a fiber form. The larger the number of nozzle openings, the higher the productivity is expected. In the drawing, the maximum draw ratio may vary depending on the resin and depending on the melt viscosity.

The ultrasonic treatment may be performed by: ultrasonic waves having a frequency of 24kHz and an amplitude of 60% were applied to the resin for 2 hours by, for example, adding glycerol (available from Tokyo Chemical Industry co., Ltd, reagent grade) solvent to the resin in an amount about 5 times greater than the amount of resin, subsequently heating the resin to a temperature 20 ℃ above the melting point, and then using an ultrasonic generator (available from Hielscher Ultrasonics Gmb, hurtrasiconer UP 200S). Subsequently, the resin is washed, preferably at room temperature, with isopropanol solvent and then dried under vacuum.

The external electric field application treatment may be performed by: by heating the resin powder, for example, at a temperature higher than or equal to the glass transition temperature, followed by applying an alternating electric field of 600V/cm (500Hz) to the resin powder for 1 hour, and then slowly cooling the resin powder.

Especially in the PBF method in the powder lamination method, a wide temperature width (temperature window) which varies with respect to the crystal layer is very effective because the crystal warpage having a wide temperature window can be suppressed and the object generation stability can be improved. Therefore, it is preferable to use a resin powder having a large difference between the melting start temperature and the recrystallization temperature during cooling. Crystalline thermoplastic resins are particularly suitable for use.

When the resin satisfies at least one selected from the group consisting of (1) to (3) described below, the resin may be identified as a crystalline thermoplastic resin.

(1) In differential scanning calorimetry measurements performed according to ISO 3146, the melting onset temperature Tmf1 of the endothermic peak when the resin is heated to a temperature above the melting point 30 ℃ at a rate of 10 ℃/min and the melting onset temperature Tmf2 of the endothermic peak when the resin is subsequently cooled to less than or equal to-30 ℃ at a rate of 10 ℃/min and then reheated to a temperature above the melting point 30 ℃ at a rate of 10 ℃/min are in the relationship Tmf1> Tmf 2. The melting start temperature of the endothermic peak is a temperature decreased by-15 mW from a straight line drawn in parallel with the x-axis toward the low temperature side from a position where the calorific value becomes constant after completion of the endothermic at the melting point.

(2) In differential scanning calorimetry measurements performed according to ISO 3146, the crystallinity Cd1 obtained from the amount of energy of the endothermic peak when the resin is heated to a temperature above the melting point by 30 ℃ at a rate of 10 ℃/min and the crystallinity Cd2 obtained from the amount of energy of the endothermic peak when the resin is subsequently cooled to less than or equal to-30 ℃ at a rate of 10 ℃/min and then heated again to a temperature above the melting point by 30 ℃ at a rate of 10 ℃/min are in the relationship Cd1> Cd 2.

(3) The crystallinity Cx1 obtained by X-ray diffraction measurement and the crystallinity Cx2 obtained by X-ray diffraction measurement conducted after the resin was heated to a temperature 30 ℃ higher than the melting point at a rate of 10 ℃/min, subsequently cooled to-30 ℃ or lower at a rate of 10 ℃/min, and then further heated to a temperature 30 ℃ higher than the melting point at a rate of 10 ℃/min in a nitrogen atmosphere are in the relationship Cx1> Cx 2.

The above (1) to (3) define the characteristics of the same resin powder from different angles. (1) To (3) are related to each other. A resin satisfying at least one of (1) to (3) is effective. (1) The measurement of (1) to (3) can be carried out, for example, by the following method.

< method for measuring melting Start temperature by differential scanning calorimetry in Condition (1) >

In the method of measuring the melting start temperature by Differential Scanning Calorimetry (DSC) in condition (1), the melting start temperature (Tmf1) of the endothermic peak when the resin is heated to a temperature higher than the melting point by 30 ℃ at a rate of 10 ℃/min is measured with a differential scanning calorimeter (available from Shimadzu Corporation, DSC-60A) according to the measurement method of ISO 3146 (plastic transition temperature measurement method, JIS K7121). Then, the melting start temperature (Tmf2) of the endothermic peak when the resin was subsequently cooled to less than or equal to-30 ℃ at a rate of 10 ℃/min and then heated to a temperature of 30 ℃ above the melting point at a rate of 10 ℃ was measured. The melting start temperature of the endothermic peak is a temperature decreased by-15 mW from a straight line drawn in parallel with the x-axis toward the low temperature side from a position where the calorific value after completion of the endothermic at the melting point becomes constant.

< method for measuring crystallinity by differential scanning calorimetry in the Condition (2) >

In the method of measuring crystallinity by Differential Scanning Calorimetry (DSC) in condition (2), the amount of energy (heat of fusion) of an endothermic peak when the resin is heated to a temperature higher than the melting point by 30 ℃ at a rate of 10 ℃/min is measured according to ISO 3146 (plastic transition temperature measuring method, JIS K7121). The crystallinity (Cd1) can be obtained from the fusion heat, relative to the perfect crystal fusion heat. Then, the amount of energy of the endothermic peak when the resin was subsequently cooled to-30 ℃ or lower at a rate of 10 ℃/min and then heated to a temperature of 30 ℃ higher than the melting point at a rate of 10 ℃/min was measured. The crystallinity (Cd2) can be obtained from the fusion heat, relative to the perfect crystal fusion heat.

< method for measuring crystallinity by X-ray Analyzer in Condition (3) >

In the method of measuring crystallinity by an X-ray analyzer in the condition (3), the obtained powder is placed on a glass plate, and the crystallinity (Cx1) of the powder may be measured with an X-ray analyzer (available from Bruker corp., DISCOVER 8) including a two-dimensional detector whose 2 θ range is set to 10 to 40 at room temperature. Next, in DSC, the powder is heated at a rate of 10 ℃/min to a temperature 30 ℃ above the melting point, held for 10 minutes, and cooled at a rate of 10 ℃/min to-30 ℃. Subsequently, the sample was returned to room temperature, and the crystallinity of the sample (Cx2) can be measured in the same manner as Cx 1.

The resin powder for fabricating the three-dimensional object may be used for the SLS method and the SMS method. The resin powder exhibits an appropriate balance of characteristics in terms of parameters such as an appropriate particle size, particle size distribution, heat transfer characteristics, melt viscosity, bulk density, flowability, melting temperature, and recrystallization temperature.

In order to increase the degree of laser sintering in the PBF method, it is preferable that the resin powder used to make the three-dimensional object has a high bulk density, although the resin inherently has a variation in density. The tap density of the resin powder is more preferably 0.35g/mL or more, still more preferably 0.40g/mL or more, and particularly preferably 0.5g/mL or more.

The three-dimensional object produced by laser sintering using the resin powder for producing the three-dimensional object is smooth and may have a surface exhibiting sufficient resolution lower than or equal to the smallest orange peel. Here, orange peel generally refers to the presence of surface defects, such as an improperly rough surface, or voids or deformations on the surface of a three-dimensional object produced by laser sintering in PBF. For example, voids not only detract from aesthetics, but may also significantly affect mechanical strength.

Further, it is preferable that the three-dimensional object produced by laser sintering using the resin powder for producing the three-dimensional object does not exhibit incorrect processing characteristics such as warpage, deformation, and fuming due to the phase change occurring during sintering and during cooling thereafter.

By using the resin powder for making the three-dimensional object of the present disclosure, a three-dimensional object having high dimensional accuracy, high strength, and excellent surface characteristics (orange peel characteristics) can be obtained. Further, the resin powder has excellent recyclability, and therefore, it is possible to ensure reuse of an excessive amount of residual powder particles, thereby suppressing deterioration in dimensional accuracy and strength of the three-dimensional object.

< method for producing pellets >

The resin powder used to make the three-dimensional objects of the present disclosure may be obtained by: for example, a method of obtaining a resin in the form of fibers and then cutting the fibers to directly obtain approximately columnar particles (approximately cylindrical or polygonal prism), a method of obtaining similar columnar bodies from a film-like body, or a method of processing the obtained polygonal prism particles into approximately cylindrical bodies after the polygonal prism particles are produced.

Approximately columnar particles-

The resin powder used to make the three-dimensional objects of the present disclosure preferably includes approximately columnar particles. Near-columnar particles are particles having a columnar or tubular shape with a bottom surface and a top surface. The shapes of the bottom surface and the top surface are not particularly limited and may be appropriately selected depending on the intended purpose, and thus the approximately columnar particles may be approximately columnar bodies or polygonal prism bodies. When the bottom surface and the top surface have a circular or elliptical shape, the approximately columnar particles are approximately columnar bodies (fig. 1). When the bottom surface and the top surface have a polygonal shape such as a quadrangle or a hexagon, the approximately columnar particles are polygonal prisms. The bottom surface and the top surface may have the same shape or different shapes as long as there is a columnar or tubular region between the bottom surface and the top surface. The approximately columnar particles may be straight columnar bodies whose columnar portions (side surfaces) are orthogonal to the bottom surface and the top surface, or may be diagonal columnar bodies whose columnar portions are not orthogonal to the bottom surface and the top surface.

The resin powder having an approximately columnar shape can provide a powder having a small angle of repose and high powder surface smoothness during recoating. This may provide a three-dimensional object with improved surface properties. In terms of productivity and stability of the production object, it is more preferable that the approximately columnar body is closer to a straight columnar body whose bottom surface and top surface are approximately parallel to each other. The approximately columnar shape can be discriminated by observation, for example, with a scanning electron microscope (apparatus name: S4200, available from Hitachi, Ltd.) or a wet flow type particle diameter/shape analyzer (apparatus name: FPIA-3000, available from Sysmex Corporation).

The content of the approximately columnar particles is preferably 50% or more, more preferably 75% or more, and particularly preferably 90% or more, with respect to the total amount of the resin powder used for making the three-dimensional object. When the content of the approximately columnar particles is 50% or more, there is a remarkable effect of increasing the packing density. This is very effective for improving the dimensional accuracy and strength of the three-dimensional object to be obtained.

-approximation of a cylinder-

The approximately columnar body is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the approximately columnar body include a true columnar body and an elliptical columnar body. Of these approximately columnar bodies, a body closer to the true column is more preferable. When the ratio of the longer diameter to the shorter diameter (longer diameter/shorter diameter) is 1 to 10, the approximately columnar body is referred to as "approximately columnar". A columnar body having a partially cut circular shape is also included in the approximate cylinder.

Preferably, the approximately cylindrical body has approximately circular facing surfaces. The facing surfaces may have different circular diameters. However, in terms of the effectiveness of increasing the density, the ratio of the circular diameter of the larger surface to the circular diameter of the smaller surface (larger surface/smaller surface) is preferably 1.5 or less, more preferably 1.1 or less.

The longer side of the bottom surface of the approximately columnar body is not particularly limited, may be appropriately selected according to the intended purpose, and may have a length of 5 micrometers or more but 200 micrometers or less. The longer side of the bottom surface of the approximately columnar particle refers to the diameter of the bottom surface. When the circular portion of the approximately columnar particle has an elliptical shape, the longer side refers to a longer diameter. The height of the approximately columnar body (i.e., the distance between the bottom surface and the top surface) is not particularly limited, may be appropriately selected depending on the intended purpose, and is preferably 5 micrometers or more but 200 micrometers or less. When the longer side of the bottom surface is within this range, the resin powder can be suppressed from curling during formation of the powder layer. This makes the surface of the powder layer smooth and reduces voids formed between the resin powder particles, resulting in the effect of further improving the surface characteristics and dimensional accuracy of the three-dimensional object.

The resin powder may contain particles whose bottom surface is longer and whose height is less than 5 micrometers or more than 200 micrometers. However, it is preferred that the content of these particles is low. Specifically, it is preferable that the longer side of the bottom surface thereof and the particles having a height of 5 micrometers or more but 200 micrometers or less account for 50% or more, more preferably 75% or more of all the particles.

Examples of the method for forming the fiber form include a method of drawing a resin melt with an extruder while stirring the resin melt at a temperature 30 ℃ or more higher than the melting point to have a fiber form. Here, the resin melt is preferably drawn to a size about 1 times or more but 10 times or less large to have a fiber form. In this case, the shape of the bottom surface of the columnar body is determined by the shape of the nozzle opening of the extruder. For example, when the shape of the bottom surface of the columnar body, i.e., the cross-sectional shape of the fiber, is circular, a nozzle opening having a circular shape is used. When the shape of the bottom surface of the columnar body is a polygon, the nozzle opening is selected according to the polygon shape. It is preferred that the three-dimensional object has as high a dimensional accuracy as possible. The number of nozzle openings is preferably the maximum possible in terms of increased productivity.

Examples of the method for cutting the fibers include a guillotine-type cutting device provided with blades on both the upper side and the lower side, and a so-called press-cutting device having a plate instead of the blades on the lower side and configured to cut an article with the upper blade. These types of devices known so far can be used. Examples of these types of apparatus known to date include apparatus configured to cut articles directly to a size of 0.005mm or more but 0.2mm or less, and apparatus for cutting articles with, for example, CO ₂ A method of laser cutting an article. These devices are suitable for use. With these methods, a resin powder for making the three-dimensional object of the present disclosure can be obtained.

The method for pulverizing the resin particles is also effective in use. For example, the resin in the form of, for example, particles is mechanically pulverized with a pulverizer known so far, and particles other than particles having a desired particle diameter are classified and removed. The temperature during pulverization is preferably 0 ℃ or less (lower than or equal to the brittleness temperature of the resin), more preferably-25 ℃ or less, and particularly preferably-100 ℃ or less. These temperatures are effective because the pulverization efficiency is improved.

The resin powder used to fabricate the three-dimensional object of the present disclosure may be used to fabricate a three-dimensional product by using, for example, a laser sintering method according to the PBF method, such as a Selective Laser Sintering (SLS) method or a Selective Mask Sintering (SMS) method.

(three-dimensional object producing method and three-dimensional object producing apparatus)

The method for manufacturing the three-dimensional object comprises the following steps: a layer forming step of forming a resin powder layer for making a three-dimensional object of the present disclosure; and a powder bonding step for irradiating selected regions of the formed layer with electromagnetic waves to bond the particles of the resin powder to each other. The method of fabricating a three-dimensional object repeats the layer forming step and the powder bonding step. The three-dimensional object generation method may also include other steps as necessary.

The three-dimensional object manufacturing apparatus includes: a layer forming unit configured to form a layer of the resin powder of the present disclosure; and a powder bonding unit configured to bond particles of the resin powder for producing a three-dimensional object in a selected region of the layer to each other, and further including other units as necessary.

The three-dimensional object generation method can be advantageously performed by using a three-dimensional object fabrication apparatus. As the resin powder for producing a three-dimensional object, a resin powder similar to that for producing the three-dimensional object of the present disclosure can be used.

The resin powder for producing a three-dimensional object can be used for all three-dimensional object producing apparatuses of the powder laminate type, and is effective. The three-dimensional object manufacturing apparatus of the powder laminate type is changed in a unit configured to bond particles of the resin powder in a selected area to each other after the powder layer is formed, and examples of the unit include an electromagnetic radiation unit, which is generally represented by an SLS system and an SMS system; and a liquid discharge unit represented by an adhesive injection system. The resin powder used to make the three-dimensional objects of the present disclosure can be used in all of these systems and is effective for all three-dimensional object making apparatuses including the powder lamination unit.

The powder binding unit is not particularly limited and may be appropriately selected depending on the intended purpose. The powder bonding unit (examples of which include a unit configured to perform electromagnetic wave radiation.

In three-dimensional object fabricating apparatuses such as SLS type and SMS type employing electromagnetic wave radiation, examples of electromagnetic radiation sources for electromagnetic wave radiation include lasers for radiating, for example, ultraviolet rays, visible rays and infrared rays, microwaves, electric discharges, electron beams, radiation heaters and LED lamps or any combination of these sources.

In the case of employing electromagnetic wave radiation as a method for selectively binding particles of a resin powder for producing a three-dimensional object to each other, there is a method of selectively employing promotion of effective absorption or interference absorption. For example, a method of adding an absorbent or an inhibitor to the resin powder may be employed.

An example of such a three-dimensional object producing apparatus will be described with reference to fig. 2. Fig. 2 is a schematic diagram showing an example of a three-dimensional object producing apparatus. As shown in fig. 2, the powder is stored in a powder supply tank 5 and is fed to a laser scanning space 6 using a roller 4 according to the amount of use. Preferably, the supply tank 5 is temperature regulated by the heater 3. The laser scanning space 6 is irradiated with laser light output from the electromagnetic radiation source 1 via the mirror 2. The powder is sintered by the heat of the laser. As a result, a three-dimensional object can be obtained.

The temperature of the supply tank 5 is preferably 10 ℃ or higher below the melting point of the powder.

The temperature of the partial bed in the laser scanning space is preferably 5 ℃ or higher below the melting point of the powder.

The laser power is not particularly limited and may be appropriately selected depending on the intended purpose, and is preferably 10 watts or more but 150 watts or less.

In another embodiment, the three-dimensional objects of the present disclosure may be fabricated using Selective Mask Sintering (SMS) techniques. As the SMS process, for example, the process described in U.S. patent No.6,531,086 is suitably used.

In the SMS process, a shadow mask is used to selectively block infrared radiation and selectively irradiate a portion of a powder layer with infrared rays. In the case where the SMS process for fabricating the three-dimensional object is used together with the resin powder for fabricating the three-dimensional object of the present disclosure, a material that enhances the infrared absorption characteristics of the resin powder may be and is effectively added. For example, one or more endothermic agents or one or more dark colored materials (e.g., carbon fibers, carbon black, carbon nanotubes or carbon fibers and cellulose nanofibers) or both one or more endothermic agents and one or more dark colored materials may be added.

In yet another embodiment, a three-dimensional object can be fabricated using a three-dimensional object fabrication apparatus of a resin powder and binder jetting type for fabricating a three-dimensional object of the present disclosure. The method includes a layer forming step of forming a resin powder layer for making the three-dimensional object of the present disclosure and a powder bonding step of discharging a liquid to a selected area of the formed layer and drying the liquid to bond particles of the resin powder to each other. The method repeats the layer forming step and the powder bonding step. The method may also include other steps as desired.

The three-dimensional object manufacturing apparatus includes: a layer forming unit configured to form a layer of resin powder for making a three-dimensional object of the present disclosure; and a unit configured to discharge liquid to selected areas of the formed layer, and other units as needed. The unit configured to discharge the liquid is preferably of an ink jet type in terms of dimensional accuracy of the three-dimensional object to be obtained and object generation speed.

Fig. 3 shows an example of a schematic diagram of an adhesive jetting type process. The three-dimensional object manufacturing apparatus shown in fig. 3 includes a forming-side powder storage tank 11 and a supply-side powder storage tank 12. Each powder storage tank comprises a state 13 which is movable upwards and downwards. By placing the resin powder of the present disclosure on the stage 13, a layer of resin powder for making a three-dimensional object is formed. Above the formation-side powder storage tank 11, the three-dimensional object fabrication apparatus includes a three-dimensional object fabrication liquid material supply unit 15 configured to discharge a liquid material 16 for creating a three-dimensional object toward resin powder for creating a three-dimensional object in the powder storage tank, and also includes a resin powder layer forming unit 14 (hereinafter, may also be referred to as a leveling mechanism or a recoater) capable of supplying resin powder for creating a three-dimensional object from the supply-side powder storage tank 12 to the formation-side powder storage tank 11 and leveling the surface of the resin powder (layer) in the formation-side powder storage tank 11.

Fig. 3A and 3B show a step of supplying the resin powder from the supply-side powder storage tank 12 to the formation-side powder storage tank 11 and forming a resin powder layer having a smooth surface. The platform 13 of the formation-side powder storage tank 11 and the supply-side powder storage tank 12 is controlled to have a gap capable of obtaining a desired layer thickness, and the resin powder layer forming unit 14 is moved from the supply-side powder storage tank 12 to the formation-side powder storage tank 11. In this way, a resin powder layer is formed in the formation-side powder storage tank 11.

Fig. 3C shows a step of dropping the liquid material 16 for producing a three-dimensional object onto the resin powder layer in the formation-side powder storage tank 11 by the object-producing liquid supply unit 15. Here, the position on the resin powder layer where the liquid material 16 for generating the three-dimensional object falls is determined based on two-dimensional image data (slice data) representing a number of planar layers of the cut three-dimensional object.

In fig. 3D and 3E, the platform 13 of the supply-side powder storage tank 12 is raised, and the platform 13 of the formation-side powder storage tank 11 is lowered to control the gap capable of achieving a desired layer thickness. The resin powder layer forming unit 14 is again moved from the supply-side powder storage tank 12 to the formation-side powder storage tank 11. In this way, a new resin powder layer is formed in the formation-side powder storage tank 11.

Fig. 3F shows a step of dropping the liquid material 16 for producing a three-dimensional object again onto the resin powder layer in the formation-side powder storage tank 11 by the three-dimensional object producing liquid material supply unit 15. These series of steps are repeated, and drying is performed as necessary to remove resin powder particles (excess powder particles) to which the liquid material for making the three-dimensional object is not attached. In this way, a three-dimensional object can be obtained.

The binder is preferably added to bind the resin powder particles to each other. The binder may be added in a state of being dissolved in the liquid to be discharged, or may be mixed in the form of binder particles in the resin powder. The binder is preferably dissolved in the liquid to be discharged. For example, when the liquid to be discharged contains water as a main component, it is preferable that the binder is water-soluble.

Examples of the water-soluble binder include polyvinyl alcohol (PVA), polyvinyl pyrrolidone, polyamide, polyacrylamide, polyethyleneimine, polyethylene oxide, polyacrylic acid resin, cellulose resin, and gelatin. Among these water-soluble binders, polyvinyl alcohol is more preferably used to increase the strength and dimensional accuracy of the three-dimensional object.

The resin powder used for making the three-dimensional object of the present disclosure has high fluidity, and therefore the surface characteristics of the three-dimensional object to be obtained can be improved. The effect is not limited to the method using electromagnetic radiation, but can also be exerted in all three-dimensional object making apparatuses using a powder lamination method such as an adhesive jetting method.

(three-dimensional object)

According to the three-dimensional object manufacturing method of the present disclosure, a three-dimensional object can be advantageously manufactured.

Examples of the invention

The present disclosure will be described more specifically by way of examples. The present disclosure should not be construed as limited to these examples.

The "average equivalent circle diameter, average circularity, and median of particle size distribution based on the equivalent circle diameter" and "loose-fill ratio" of the obtained resin powder for making three-dimensional objects were measured in the following manner. The results are shown in table 1 below.

< mean equivalent circle diameter, mean circularity, and median of particle size distribution based on equivalent circle diameter >

For the average equivalent circle diameter and the average circularity, when the number of powder particles is 3,000 or more, an image of the particle shape is taken with a wet flow type particle diameter/shape analyzer (equipment name: FPIA-3000, available from Sysmex Corporation), and the equivalent circle diameter and circularity of particles having a particle diameter of 0.5 micron or more but 200 microns or less are measured, and the average value of the equivalent circle diameter and the average value of the circularity are calculated. Two circularity measurements were made and the average of the two measurements was used as the average circularity. The median value is calculated from the particle size distribution based on the equivalent circle diameter.

< Loose filling ratio >

For the bulk filling ratio, the bulk density was measured with a bulk densitometer (in accordance with JIS Z-2504, available from Kuramochi Scientific Instruments). The obtained bulk density was divided by the true density of the resin to calculate the "loose fill" of the powder.

(example 1)

Polybutylene terephthalate (PBT) resin (product name: NOVADURAN5020, available from Mitsubishi Engineering-Plastics Corporation, melting point 218 ℃ C., glass transition temperature 43 ℃ C.) was stirred at a temperature higher than 30 ℃ melting point. Then, the solution in which the resin for making a three-dimensional object is dissolved is drawn with an extruder (available from Japan Steel Works, Ltd) using a nozzle opening having a circular shape to have a fiber form. This operation was performed with the number of strands extruded from the nozzle set to 60 strands. The solution was drawn to a size of approximately 5 times larger so that the diameter of the fibers was 55 microns so that fibers with an accuracy of ± 4 microns were obtained, then adjusted to 55 microns, and the fibers were cut with a desired length of 55 microns with a press-cutting device (available from Ogino Seiki co., Ltd, NJ SERIES 1200TYPE) to obtain approximately columnar particles, which were used as resin powder for producing three-dimensional objects. The cross section resulting from the cutting was observed with a scanning electron microscope (apparatus name: S4200, available from Hitachi, Ltd.) at a magnification of X300. As a result, the cross section is neatly cut, and the cut surfaces are parallel to each other. The height of the approximately columnar body is measured. As a result, it was found that an accuracy of 55 micrometers ± 10 micrometers could be achieved by cutting. The obtained resin powder for producing a three-dimensional object was passed through a sieve having a mesh size of 125 μm to remove coarse particles caused by partial cutting failure. Fig. 4 shows the distribution of the equivalent circle diameters of the resin powder used to make the three-dimensional object of example 1.

(example 2)

A resin powder for producing a three-dimensional object was obtained in the same manner as in example 1 except that the polybutylene terephthalate (PBT) resin of example 1 was changed to a polyamide 66(PA66) resin (product name: LEONA 1300S, available from Asahi Kasei Chemicals Corporation, melting point 265 ℃), with the intended fiber diameter set to 140 micrometers and the intended fiber length set to 140 micrometers.

(example 3)

A resin powder for producing a three-dimensional object was obtained in the same manner as in example 1 except that the polybutylene terephthalate (PBT) resin of example 1 was changed to a polyamide 9T (PA9T) resin (product name: GENESTAR N1000A, available from Kuraray co., Ltd, melting point 306 ℃), with the intended fiber diameter set to 15 micrometers and the intended fiber length set to 15 micrometers.

(example 4)

Resin powder for making a three-dimensional object was obtained in the same manner as in example 1 except that the polybutylene terephthalate (PBT) resin of example 1 was changed to a Polypropylene (PP) resin (product name: NOVATEC MA3, available from Japan Polypropylene Corporation, melting point 130 ℃, glass transition temperature 0 ℃), with the intended fiber diameter set to 55 micrometers and the intended fiber length set to 55 micrometers.

(example 5)

A resin powder for producing a three-dimensional object was obtained in the same manner as in example 1 except that the polybutylene terephthalate (PBT) resin of example 1 was changed to a Polyetheretherketone (PEEK) resin (product name: HT P22PF, available from VICTREX PLC, melting point of 334 ℃, glass transition temperature of 143 ℃), with the intended fiber diameter set to 55 micrometers and the intended fiber length set to 55 micrometers.

(example 6)

Resin powder for making a three-dimensional object was obtained in the same manner as in example 1 except that polybutylene terephthalate (PBT) resin was changed to Polyacetal (POM) resin (product name: IUPITAL F10-01, available from Mitsubishi Engineering-Plastics Corporation, melting point 175 ℃), with the intended fiber diameter set to 55 micrometers and the intended fiber length set to 55 micrometers.

(example 7)

The resin powder for producing a three-dimensional object obtained in example 1 was subjected to a stirring treatment in a stainless steel container. The agitation treatment was performed for 30 minutes in a stainless steel vessel obtained from Misugi co.

The relationship between the weight of the resin powder for producing a three-dimensional object put in a stainless steel container and the area of the inner wall of the container was 1[ kg/m ] ² ]. After this operation, the powder is transferred by gravity into another container and the powder particles adhering to the wall surface are separated and disposed of. Through these operations, a resin powder for making the three-dimensional object of example 7 was obtained.

(example 8)

The resin powder for producing a three-dimensional object obtained in example 4 was subjected to a stirring treatment in a stainless steel container in the same manner as in example 7 to obtain a resin powder for producing a three-dimensional object of example 8.

(example 9)

The resin powder for producing a three-dimensional object obtained in example 1 was passed through an air conveyance system. The tubing is made of stainless steel.

The relationship between the weight of the resin powder used for making the three-dimensional object passing through the air transportation system formed of stainless steel and the area of the inner wall of the container was 1[ kg/m ] ² ]. The powder particles attached to the wall surface by this operation are separated and disposed of. By this operation, a resin powder for producing the three-dimensional object of example 9 was obtained.

(example 10)

The resin powder for fabricating a three-dimensional object obtained in example 4 was subjected to a stirring process in a stainless steel container in the same manner as in example 9 to obtain the resin powder for fabricating a three-dimensional object of example 10.

(comparative example 1)

A resin powder for making a three-dimensional object was obtained in the same manner as in example 1, except that, unlike example 1, an operation of forming pellets by machining was not performed, but a powder material formed of PA12 (product name: ASPEX-PA, available from Aspect inc.). Fig. 5 shows the distribution of equivalent circle diameters of the resin powder used to make the three-dimensional object of comparative example 1.

(comparative example 2)

A resin powder for making a three-dimensional object was obtained in the same manner as in example 1, except that, unlike example 1, an operation of forming particles by machining was not performed, but a powder material formed of PA11 (product name: ASPEX-FPA, available from Aspect inc.). Fig. 6 shows the distribution of equivalent circle diameters of the resin powder used to make the three-dimensional object of comparative example 2.

(comparative example 3)

A resin powder for making a three-dimensional object was obtained in the same manner as in example 1, except that, unlike example 1, an operation of forming particles by machining was not performed, but a powder material formed of PPS was used (product name: ASPEX-PPS, available from Aspect inc.).

(comparative example 4)

A resin powder for fabricating a three-dimensional object was obtained in the same manner as in example 1, except that, unlike in example 1, a polybutylene terephthalate (PBT) resin was freeze-pulverized at-200 ℃ with a cryogenic grinding system (equipment name: linex MILL LX1, available from Hosokawa Micron Corporation) to obtain a resin powder for fabricating a three-dimensional object.

The obtained resin powder for producing a three-dimensional object was evaluated in terms of "dimensional accuracy", "surface property (orange peel property)", "tensile strength", and "object density" in the following manner. The results are shown in table 1 below.

(dimensional accuracy)

The obtained resin powder for fabricating a three-dimensional object was stored at a temperature of 27 ℃ and a humidity of 80% RH for 1 week. The three-dimensional object was produced using the resin powder for producing a three-dimensional object after storage for 1 week and an SLS type three-dimensional object producing apparatus (available from Ricoh Company, Ltd, AM S5500P). The set conditions included an average thickness of the powder layer of 0.1mm, a laser power of 10 watts or more but 150 watts or less, a laser scanning space of 0.1mm, and a bed temperature of-3 ℃ from the melting point of the resin.

The samples used for the dimensional accuracy evaluation were rectangular parallelepipeds, 50mm long on each side and 5mm in average thickness. Three-dimensional objects are generated based on CAD data and used as samples for dimensional accuracy assessment. The difference between the length of each side of the CAD data of the sample for dimensional accuracy evaluation and the length of each side of the sample actually made is calculated and averaged as a dimensional difference. The "dimensional accuracy" was evaluated according to the following evaluation criteria.

< evaluation criteria >

A: the size difference is 0.02mm or less.

B: the size difference is greater than 0.02mm but 0.05mm or less.

C: the size difference is greater than 0.05mm but 0.10mm or less.

D: the size difference is greater than 0.10mm and 0.15mm or less.

(surface Properties (orange Peel Properties))

The surface of the three-dimensional object sample for evaluation of "dimensional accuracy" was subjected to visual observation, optical microscope observation and sensory analysis. In sensory analysis, the sample was touched by hand, and surface properties, particularly smoothness, were evaluated based on tactile sensation. The results were added to evaluate the surface characteristics (orange peel characteristics) according to the evaluation criteria described below.

< evaluation criteria >

A: the surface is very smooth with little noticeable roughness or roughness.

B: the surface has a smooth, unproblematic surface and tolerable surface irregularities or roughness.

C: the surface is not smooth, and obvious concave-convex and roughness are provided.

D: the surface is scratched and has many defects such as surface irregularities and deformations.

(tensile Strength)

As in the "dimensional accuracy" evaluation, 5 tensile test samples were produced using a resin powder for producing a three-dimensional object after 1 week of storage, and using the same equipment and the same conditions as those for producing the samples for dimensional accuracy evaluation, such that the samples were arranged side by side with the longer direction of the samples parallel to the Y-axis direction and the center of the samples located in the Y-axis direction. The spacing between the object layers was 5 mm. For the tensile specimen, a multipurpose dog bone specimen of type 1A (center portion of the specimen having a length of 80mm, a thickness of 4mm and a width of 10 mm) conforming to ISO (international organization for standardization) 3167 was used.

The tensile strength of the obtained tensile specimen sample (three-dimensional object) was measured using a tensile tester conforming to ISO 527 (available from Shimadzu Corporation, AGS-5 KN). The test speed in the tensile test was 50 mm/min. Based on the average value of the tensile strength values of the obtained 5 tensile specimen samples, the tensile strength evaluation was performed according to the following evaluation criteria.

< evaluation criteria >

A: the tensile strength is 100MPa or more.

B: a tensile strength of 50MPa or more but less than 100MPa

C: the tensile strength is 30MPa or more but less than 50 MPa.

D: the tensile strength is lower than 30 MPa.

(object Density)

Three-dimensional object samples for evaluation of "dimensional accuracy" were measured according to the Archimedes method (equipment name: AD-1653/AD-1654, available from A & D Company, Ltd.). Ion-exchanged water was used as a sample solvent. The measurement is carefully performed without attaching air bubbles around the sample.

[ Table 1]

For example, aspects of the present disclosure are as follows.

<1> a resin powder for fabricating a three-dimensional object,

wherein the resin powder has a number average equivalent circle diameter of 10 μm or more but 150 μm or less, and

wherein the median value of the particle size distribution based on the equivalent circle diameter of the resin powder is higher than the average value in the particle size distribution based on the equivalent circle diameter.

<2> the resin powder for fabricating three-dimensional objects according to <1>,

wherein the particles of the resin powder comprise columnar particles.

<3> the resin powder for fabricating three-dimensional objects according to <2>,

wherein the columnar particles have a column length of 10 micrometers or more but 150 micrometers or less and a column diameter of 10 micrometers or more but 150 micrometers or less.

<4> the resin powder for fabricating three-dimensional objects according to any one of <1> to <3>,

wherein the average circularity of the resin powder is 0.75 or more but 0.90 or less.

<5> the resin powder for fabricating a three-dimensional object according to any one of <1> to <4>, the resin powder comprising:

the resin is crystallized and the resin is crystallized,

wherein the crystalline resin is at least one selected from the group consisting of polyolefin, polyamide, polyester, polyarylketone, and polyphenylene sulfide.

<6> the resin powder for fabricating three-dimensional objects according to <5>,

wherein the polyester is at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polylactic acid.

<7> the resin powder for fabricating three-dimensional objects according to <5> or <6>,

wherein the polyolefin is polyethylene or polypropylene.

<8> the resin powder for fabricating a three-dimensional object according to any one of <1> to <7>, further comprising an antioxidant.

<9> the resin powder for fabricating three-dimensional objects according to <8>,

wherein the content of the antioxidant is 0.05 mass% or more but 5 mass% or less.

<10> the resin powder for fabricating a three-dimensional object according to <9>,

wherein the content of the antioxidant is 0.1 mass% or more but 3 mass% or less.

<11> the resin powder for fabricating three-dimensional objects according to <10>,

wherein the content of the antioxidant is 0.2 mass% or more but 2 mass% or less.

<12> the resin powder for fabricating a three-dimensional object according to any one of <1> to <11>, further comprising a plasticizer.

<13> the resin powder for fabricating a three-dimensional object according to any one of <1> to <12>, further comprising a stabilizer.

<14> the resin powder for fabricating a three-dimensional object according to any one of <1> to <13>, further comprising a nucleating agent.

<15> the resin powder for fabricating a three-dimensional object according to any one of <1> to <14>, further comprising a toughening agent.

<16> the resin powder for fabricating three-dimensional objects according to <15>,

wherein the toughening agent is at least one selected from the group consisting of glass filler, glass beads, carbon fibers, and aluminum balls.

<17> the resin powder for fabricating three-dimensional objects according to <16>,

wherein the toughening agent is at least any one of a glass filler and a carbon fiber.

<18> the resin powder for fabricating three-dimensional objects according to <17>,

wherein the toughening agent is carbon fiber.

<19> a method for producing a three-dimensional object, comprising:

a layer forming step of forming a layer including the layer of resin powder for producing a three-dimensional object according to any one of <1> to <18 >; and

a powder bonding step of bonding particles of the resin powder for producing a three-dimensional object in selected regions of the layer to each other,

wherein the method of making a three-dimensional object repeats the step of layer formation and the step of powder bonding.

<20> a three-dimensional object fabrication apparatus comprising:

a layer forming unit configured to form a layer of the resin powder for producing a three-dimensional object according to any one of <1> to <18 >; and

a powder bonding unit configured to bond particles of the resin powder for producing the three-dimensional object in the selected region of the layer to each other.

<21> the three-dimensional object fabrication apparatus according to <20>,

wherein the powder bonding unit is a unit configured to perform electromagnetic wave radiation.

<22> a three-dimensional object fabricated by the method for fabricating a three-dimensional object <19 >.

The resin powder for producing a three-dimensional object according to any one of <1> to <18>, the production method of a three-dimensional object according to <19>, the production apparatus of a three-dimensional object according to <20> or <21>, and the three-dimensional object according to <22> can solve various problems in the related art, and can achieve the object of the present disclosure.

Claims (9)

1. A resin powder for use in the fabrication of three-dimensional objects,

wherein the resin powder has a number average equivalent circle diameter of 10 μm or more but 150 μm or less, and

wherein the median value of the particle size distribution based on the equivalent circle diameter of the resin powder is higher than the average equivalent circle diameter, and

wherein the loose-fill ratio is 40.4% or more.

2. The resin powder for producing three-dimensional objects according to claim 1,

wherein the particles of the resin powder comprise columnar particles.

3. The resin powder for producing three-dimensional objects according to claim 2,

wherein the columnar particles comprise columnar particles having bottom and top surfaces that are approximately parallel to each other.

4. The resin powder for producing three-dimensional objects according to any one of claims 2 to 3,

wherein the columnar particles have a column length of 10 microns or more but 150 microns or less, and a column diameter of 10 microns or more but 150 microns or less.

5. The resin powder for producing three-dimensional objects according to any one of claims 1 to 2,

wherein the loose-fill ratio is 40.4% or more but 50% or less.

6. The resin powder for producing three-dimensional objects according to any one of claims 1 to 2,

wherein the resin powder has an average circularity of 0.75 or more but 0.90 or less.

7. The resin powder for producing a three-dimensional object according to any one of claims 1 to 2, wherein the resin powder comprises:

the resin is crystallized and the resin is crystallized,

wherein the crystalline resin includes at least one selected from the group consisting of polyolefin, polyamide, polyester, polyarylketone, and polyphenylene sulfide.

8. The resin powder for producing three-dimensional objects according to claim 7,

wherein the polyester includes at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polylactic acid.

9. A method of making a three-dimensional object, comprising:

forming a layer comprising the resin powder for producing a three-dimensional object according to any one of claims 1 to 8; and

the particles of resin powder used to make the three-dimensional object in selected regions of the layer are bonded to each other,

wherein the method of fabricating the three-dimensional object repeats the forming and bonding.

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