JPWO2017163834A1 - Powder material and manufacturing method of three-dimensional structure - Google Patents

Abstract

It is an object of the present invention to provide a powder material and a three-dimensional modeling method that are difficult to agglomerate during preheating and that can sufficiently sinter coated particles with a small amount of laser energy. In order to solve the above problems, formation of a thin layer of a powder material containing coated particles, preheating of the thin layer, and selective laser light irradiation on the thin layer are repeated, and the coated particles are melt bonded. About the powder material used for the method of manufacturing a three-dimensional molded item by laminating | stacking a plurality of physical layers, the said covering particle shall contain core resin and shell resin which coat | covers the said core resin. At this time, the absolute value of the difference between the SP value of the core resin and the SP value of the shell resin is set to 2.5 (J / cm 3) 1/2 to 7.0 (J / cm 3) 1/2, and the shell The temperature TS (65) at which the storage elastic modulus G ′ of the resin becomes 106.5 Pa is higher than the temperature TC (65) at which the storage elastic modulus G ′ of the core resin becomes 106.5 Pa.

Description

  The present invention relates to a powder material and a method for manufacturing a three-dimensional structure.

  In recent years, various methods capable of relatively easily manufacturing a three-dimensional object having a complicated shape have been developed, and rapid prototyping and rapid manufacturing using such a method have attracted attention. As one method for producing a three-dimensional structure, a powder bed fusion bonding method is known. In the powder bed fusion bonding method, a thin layer is formed by laying flat a powder material including particles made of a resin material or a metal material. Then, a desired position of the thin layer is irradiated with a laser beam to selectively sinter or melt bond the adjacent coated particles (hereinafter also simply referred to as “melt bonding”). That is, a layer (hereinafter, also simply referred to as “modeled object layer”) obtained by finely dividing the three-dimensional modeled object in the thickness direction is formed. A three-dimensionally shaped object having a desired shape is manufactured by further spreading a powder material on the shaped object layer thus formed and repeating laser light irradiation.

  The powder bed fusion bonding method has an advantage that a three-dimensional molded article having high strength is easily obtained because of high modeling accuracy and high adhesion strength between the layered molded article layers. However, at present, resin types used in the powder bed fusion bonding method are limited to polystyrene, polyamide 11, polyamide 12, and the like, and it is required to form a three-dimensional model using more versatile resins.

  Here, in the powder bed fusion bonding method, a thin layer made of a powder material may be preheated before laser beam irradiation for the purpose of reducing the amount of laser energy used. By performing preliminary heating, warping of the three-dimensional structure to be obtained is easily suppressed. On the other hand, depending on the type of particles, the particles may aggregate during preheating, and it is difficult to sufficiently increase the preheating temperature. Therefore, in order to sufficiently melt and bond the particles, a large amount of laser energy is still necessary, and further reduction in the amount of laser energy is required from the viewpoint of improving productivity and expanding applications.

  A technique has been proposed in which the particles used in the powder bed fusion bonding method are core-shell type coated particles (see, for example, Patent Document 1). In this technology, the melt bonding force between particles is enhanced by including a fine-grained material that can be sintered or glass-formed at a temperature lower than the core particles in the shell.

  On the other hand, in the field of electrophotography, particles (toner) made of resin or the like are used, and various particles have been developed. Such toners are required to be capable of being fused onto a substrate at a low energy amount, that is, at a low temperature (low-temperature fusibility), and not to be fused during storage (storage stability). ing. Such toner for electrophotography is generally formed by a melt-kneading pulverization method or the like. However, in order to impart various functions to the particles, for example, a chemical polymerization method such as a suspension polymerization method or an emulsion aggregation method is used. In many cases, it is also manufactured by a conventional method.

  Patent Documents 2 and 3 describe coated particles (electrophotographic toner) in which particle surfaces made of a polyester resin or the like are crosslinked with an oxazoline compound to modify the particle surfaces. In the coated particles, the storage stability is enhanced by crosslinking the particle surface.

  Patent Document 4 proposes core-shell type coated particles (electrophotographic toner) having a core made of a polyester resin and a shell made of an amorphous polyester resin. In this technique, the difference in SP between the core resin and the shell resin is provided to enhance the low-temperature fixability and storage stability of the coated particles.

JP-T 2006-521264 JP 2009-058927 A JP 2010-032564 A JP2015-125404A

  As described above, the powder material used in the powder bed fusion bonding method is required to sufficiently melt and bond particles with a small amount of laser energy while the particles do not aggregate during preheating.

  In the coated particles for the powder bed fusion bonding method described in Patent Document 1, although the strength of the three-dimensional structure to be obtained is high, the fine particle material contained in the shell resin is easily melted at the time of preheating, and the coated particles at the time of preheating It was not possible to suppress the aggregation.

  On the other hand, when it is assumed that an electrophotographic toner that can be fused with a low energy amount as shown in Patent Documents 2 to 4 is adopted for the powder bed fusion bonding method, it is required for the electrophotographic toner. The degree of heat resistance differs greatly between the heat resistance and the heat resistance required during preheating in the powder bed fusion bonding method. For example, since the coated particles described in Patent Document 2 and Patent Document 3 have a low glass transition temperature, if these coated particles are employed in a powder bed melt bonding method and preheated, the particles may aggregate. Easily expected. Similarly, the electrophotographic toner described in Patent Document 4 is not sufficient in heat resistance, and if it is employed in a powder sintering molding method and preheated, particles may aggregate. That is, it is difficult to divert a conventional toner for electrophotography to a powder bed fusion bonding method in which preheating is performed.

  The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a powder material and a three-dimensional modeling method in which particles are less likely to aggregate during preheating and can sufficiently sinter coated particles with a small amount of laser energy.

The first of the present invention is the following powder material.
[1] The formation of a thin layer of a powder material containing coated particles, preheating of the thin layer, and selective laser light irradiation to the thin layer are repeated, and a plurality of shaped product layers in which the coated particles are melt-bonded are formed. A powder material used in a method for producing a three-dimensional structure by layering, wherein the coated particles include a core resin and a shell resin that coats the core resin, and the SP value of the core resin and the The absolute value of the difference in SP value of the shell resin is 2.5 (J / cm ³ ) ^{1/2 to} 7.0 (J / cm ³ ) ^1/2 , and the storage elastic modulus G ′ of the shell resin is 10 ^6.5 becomes Pa temperature _{TS (65)} has a storage modulus G of the core resin 'is higher than the temperature _{TC (65)} to become ^{10 6.5} Pa, the powder material.

'And it is ^{10 6.5} Pa Temperature _{TS (65),} the storage modulus G of the core resin' [2] The storage elastic modulus of the shell resin G temperature is ^{10 6.5} Pa _TC and ₍₆₅₎ The powder material according to [1], wherein the difference is 5 ° C. or higher and 75 ° C. or lower.
[3] The powder material according to [1] or [2], wherein in the coated particles, the thickness of the layer containing the shell resin that covers the core resin is 10 to 500 nm.
[4] The powder material according to any one of [1] to [3], wherein the coated particles have a circularity of 0.95 or more.

2nd of this invention exists in the manufacturing method of the following three-dimensional molded item.
[5] A thin layer forming step of forming a thin layer made of the powder material according to any one of [1] to [4], a preheating step of preheating the thin layer, and the preheated thin layer A laser beam irradiation step of selectively irradiating a layer with a laser beam to form a shaped article layer in which the coated particles are melt-bonded to each other, the thin layer forming step, the preliminary heating step, and the laser beam The manufacturing method of a three-dimensional molded item which repeats an irradiation process in this order several times and forms a three-dimensional molded item by laminating | stacking the said molded article layer.
[6] The preheating temperature is a temperature at which the storage elastic modulus G′c of the core resin of the coated particles is 10 ⁶ Pa or less and the storage elastic modulus G ′s of the shell resin is 10 ⁸ Pa or more. The manufacturing method of the three-dimensional molded item as described in [5].

  According to the present invention, it is difficult to agglomerate the coated particles at the time of preheating, and it is possible to provide a method and powder material capable of sufficiently sintering the coated particles with a small amount of laser energy.

FIG. 1A is a schematic cross-sectional view of coated particles in one embodiment of the present invention. FIG. 1B is a schematic cross-sectional view of a coated particle in another embodiment of the present invention. FIG. 2 is a side view schematically showing the configuration of the three-dimensional modeling apparatus in one embodiment of the present invention. FIG. 3 is a diagram showing the main part of the control system of the three-dimensional modeling apparatus in one embodiment of the present invention.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and experiments on powder materials for powder bed fusion bonding. As a result, the present inventors have a core resin and a shell resin that coats the core resin as the coated particles for the powder bed fusion bonding method, and the storage elastic modulus G ′ of the shell resin is 10 ^6.5 Pa. TS ₍₆₅₎ is capable of melting and bonding the coated particles with a low laser energy amount by adopting coated particles higher than the temperature TC _{(65) at} which the storage elastic modulus G ′ of the core resin becomes 10 ^6.5 Pa. I found. Further, in the coated particles satisfying the above relationship, by making the powder material containing coated particles in which the absolute value of the difference between the SP value of the core resin and the SP value of the shell resin is within a specific range, Regardless of the combination, it was further found that the strength of the three-dimensional modeled product was reduced and the particles were prevented from agglomerating during preheating, and a three-dimensional molded product having high strength was obtained, and the present invention was achieved.

  When core-shell type coated particles comprising a core resin having a relatively low storage modulus at a preheating temperature and a shell resin having a relatively high storage modulus at a preheating temperature are used in the powder bed melt bonding method, As a result, only the core resin is moderately softened or melted. On the other hand, since the shell resin can maintain an appropriate rigidity, it is difficult for the coated particles to bind to each other at the time of preheating, and deformation of the coated particles hardly occurs. On the other hand, when the laser beam is irradiated, the shell resin softens, dissolves, or disappears, and the coated particles are melt-bonded. At this time, since the core resin has already been softened or melted, it is not necessary to soften or melt all the core resin by laser light irradiation. That is, it is possible to bind the coated particles with a relatively small amount of laser energy.

  However, even if a shell resin having a sufficiently high storage elastic modulus is selected at the preheating temperature, the particles are aggregated due to deformation of the coated particles during the preheating or disappearance of the layer made of the shell resin. May end up. The reason is considered that the core resin and the shell resin are easily compatible with each other. When the compatibility of the core resin and the shell resin is excessive, when the core resin is softened or melted by preheating, the shell resin is dissolved in the core resin. Therefore, it is considered that the layer made of the shell resin becomes thin or the layer made of the shell resin disappears and the particles are aggregated during the preheating.

  On the other hand, when a three-dimensional model is formed using a powder material containing core-shell type coated particles, the strength of the three-dimensional model may not be sufficiently increased. The reason may be that the compatibility between the core resin and the shell resin is excessively low. If the compatibility between the core resin and the shell resin is excessively low, the softened or melted shell resin and the core resin are likely to be separated after the laser light irradiation. Therefore, it is thought that the area | region derived from shell resin and the area | region derived from core resin are formed in the obtained three-dimensional molded item, and the intensity | strength of a three-dimensional molded item falls.

  On the other hand, in the coated particles included in the powder material of the present embodiment, the absolute value of the difference between the SP value of the core resin and the SP value of the shell resin (hereinafter also referred to as “ΔSP”) is determined as described below. Range. In this embodiment, since ΔSP is reasonably large, the shell resin is difficult to dissolve in the softened core resin during preheating. Therefore, according to this embodiment, preliminary heating can be performed without agglomerating the coated particles. Since the preliminary heating can be sufficiently performed, the coated particles can be sufficiently melt-bonded even with a small amount of laser energy. On the other hand, since ΔSP is not too large, the core resin and the shell resin are compatible with each other after the laser light irradiation, and are difficult to separate. Therefore, according to this embodiment, there also exists an advantage that the intensity | strength of the three-dimensional molded item obtained from a powder material becomes high enough.

  In addition, although the said patent document 1 shows the core-shell type particle | grains for powder bed fusion bonding methods, with the said particle | grain, it is difficult to suppress aggregation of the particle | grains at the time of a preheating, and it is with a small laser energy amount. It is considered difficult to melt-bond the coated particles sufficiently. On the other hand, the above Patent Documents 2 to 4 relate to toner for electrophotography, and preheating is not performed at the time of preparation of electrophotography. Therefore, in the techniques of Patent Documents 2 to 4, sufficient consideration is not given to the problems caused by the preheating as described above, and from the viewpoint of heat resistance, the electrophotographic toners described therein are powder bed melt bonded. It is difficult to obtain coated particles for the method.

  Hereinafter, the powder material of the present embodiment will be described, and then a method for manufacturing a three-dimensional structure using the powder material will be described.

1. Powder material The powder material of this embodiment is used for manufacturing a three-dimensional structure by a powder bed fusion bonding method. More specifically, repeated preheating of the thin layer of the powder material containing the coated particles and selective laser light irradiation to the thin layer are performed to laminate a plurality of layers of the modeled object in which the coated particles are melt-bonded. And used in a method of manufacturing a three-dimensional model.

  The powder material only needs to contain at least coated particles, and may be composed only of coated particles. On the other hand, the powder material may further include a material other than the coated particles including the laser absorber and the flow agent as long as the melt bonding by laser light irradiation is not hindered.

1-1. Coated Particle The coated particle has a core resin and a structure in which this is coated with a shell resin (hereinafter, this structure is also referred to as “core-shell structure”). In this specification, the core-shell structure means that the ratio of the area of the portion covered with the shell resin in the surface of the core particles basically composed of the core resin is 90% or more. In practice, the cross section of a large number of coated particles is imaged with a transmission electron microscope (TEM), and the ratio of the coated area of the shell resin to the surface area of the core particles is calculated for 10 arbitrarily selected coated particles. And if those average values are 90% or more, it will be considered that those coated particles have a core-shell structure.

  The coated particles having a core-shell structure may be coated particles 100 in which a core particle 101 is coated with a sheet-like shell resin 102 as shown in FIG. 1A, which is a schematic cross-sectional view showing one embodiment. Further, as shown in FIG. 1B, which is a schematic cross-sectional view showing another embodiment, coated particle 100 in which core particle 101 is coated with particulate shell resin 102 may be used.

The coated particles preferably have a storage elastic modulus G′c of the core resin lower than a storage elastic modulus G ′s of the shell resin at the preheating temperature in the manufacturing method of the three-dimensional structure to be described later. When the storage elastic moduli (G′c and G ′s) of the core resin and the shell resin are in such a relationship, the core resin can be preferentially softened by preheating. Whether the storage elastic modulus (G′c and G ′s) of the core resin and the shell resin satisfies the above relationship at the preheating temperature depends on the temperature TS ₍ the storage elastic modulus G ′ of the shell resin becomes 10 ^6.5 Pa _{). 65)} and the temperature TC _{(65) at} which the storage elastic modulus G ′ of the core resin becomes 10 ^6.5 Pa can be estimated to some extent. In this embodiment, TS ₍₆₅₎ is more than TC ₍₆₅₎ . High.

In addition, it is preferable that the storage elastic modulus G'c of the core resin in the preheating temperature in the manufacturing method of the three-dimensional molded item mentioned later specifically is 10 ⁶ Pa or less, and is 10 ¹ Pa to 10 ⁶ Pa. Is more preferable, and is more preferably 10 ² Pa to 10 ⁶ Pa. When the storage elastic modulus G′c of the core resin at the preheating temperature is 10 ⁶ Pa or less, it is possible to reduce the amount of laser energy required for softening or melting the core resin at the time of laser light irradiation. On the other hand, the storage elastic modulus G ′s of the shell resin at the preheating temperature is specifically preferably 10 ⁸ Pa or more, more preferably 10 ⁸ Pa to 10 ^9.5 Pa, and more preferably 10 ^8. More preferably, it is ⁵ Pa-10 ⁹ Pa. When the storage elastic modulus G ′s of the shell resin at the preheating temperature is 10 ⁸ Pa or more, the layer made of the shell resin, that is, the outer film of the coated particles is hardly softened during the preheating. As a result, deformation of the coated particles during preheating is suppressed. Here, the preheating temperature is appropriately set according to the type of the coated particles and the like, and can be set similarly to a general powder bed fusion bonding method. The preheating temperature is preferably 50 ° C or higher and 300 ° C or lower, more preferably 100 ° C or higher and 300 ° C or lower, further preferably 100 ° C or higher and 250 ° C or lower, and 140 ° C or higher and 250 ° C or lower. More preferably it is.

Here, in this embodiment, the absolute value ΔSP of the difference between the SP value of the shell resin of the coated particles and the SP value of the shell resin is 2.5 (J / cm ³ ) ^{1/2 to} 7.0 (J / cm ³ ) ^1/2 , and preferably 2.6 (J / cm ³ ) ^{1/2 to} 6.7 (J / cm ³ ) ^1/2 . When ΔSP is 2.5 (J / cm ³ ) ^1/2 or more, the compatibility between the core resin and the shell resin is moderately suppressed, and the shell resin is difficult to dissolve in the core resin softened by the preheating. . That is, it is difficult for the layer made of the shell resin to be thinned or disappeared by the preheating, and the coated particles are hardly melt-bonded. On the other hand, if the difference between the SP value of the core resin and the SP value of the shell resin is 7.0 (J / cm ³ ) ^1/2 or less, the shell resin and the core resin are difficult to separate after laser light irradiation. It is easy to sufficiently increase the strength of the three-dimensional structure to be obtained.

  Here, the core resin and the shell resin may have any high SP value. For example, when the SP value of the shell resin is higher than that of the core resin, it is considered that when the shell resin is melted, the shell resin attempts to lower the surface tension, and fusion bonding between particles is promoted. In addition, when the SP value of the shell resin is lower than that of the core resin, it is considered that the shell resin is likely to move inside the particles when the particles are melted, and it is considered that fusion bonding between the core resins is promoted.

Here, the unit of the SP value (solubility parameter) in this specification is (J / cm ³ ) ^1/2 , and in this specification, the value at 25 ° C. is expressed unless otherwise specified. The SP value is a value δ determined based on the following equation by the Fedors method [Robert F. Fedors, Polymer Engineering and Science, 14, 47-154 (1974)].
Fedors equation: δ = (ΣΔei / ΣΔvi) ^1/2
[Where Δei is the evaporation energy (J / mol) of atoms and atomic groups, and Δvi is the molar volume (cm ³ / mol). ]
In addition, each SP value of core resin and shell resin can be measured, for example using a cloud point titration method. In this method, a polymer solution in which only the core resin or only the shell resin is dissolved is prepared. And a poor solvent is dripped at the said polymer solution, and the quantity of the poor solvent required until it produces turbidity is calculated | required. Under the present circumstances, it measures about a poor solvent (for example, water etc.) with a high SP value, and a low poor solvent (for example, n-hexane etc.), respectively. It can be calculated based on the method described in KWSuh, JMCorbett; J. Apply Polym. Sci., 12 (10), p2359-2370 (1968).

  When the coated particles are irradiated with laser light in a method for manufacturing a three-dimensional structure to be described later, the coated particles are melt-bonded due to softening, melting, or disappearance of the shell resin. Therefore, the temperature at which the shell resin softens, melts, or disappears from the viewpoint of making the shell resin soften, melt, or disappear easily by laser light irradiation, and the three-dimensional structure is manufactured in a shorter time, and the core resin The softening or melting temperature is preferably a close value. Furthermore, at the time of laser light irradiation, the specific capacity of the core resin is increased and the volume is changed by the laser light energy, but it is preferable that the volume change is small from the viewpoint of improving the modeling accuracy of the three-dimensional structure. Accordingly, the temperature difference is preferably small in order to melt-bond the coated particles while the volume change of the core resin is small. On the other hand, it is preferable that the temperature difference is not too small from the viewpoint of suppressing deformation of the coated particles during preheating, that is, suppressing softening of the shell resin.

Therefore, the difference between the above TS ₍₆₅₎ and TC ₍₆₅₎ is preferably 5 ° C. or higher and 75 ° C. or lower, more preferably 5 ° C. or higher and 70 ° C. or lower, and more preferably 10 ° C. or higher and 70 ° C. or lower. More preferably, it is more preferably 10 ° C. or more and 60 ° C. or less, and further preferably 30 ° C. or more and 60 ° C. or less.

Further, the temperature TC _{(65) at which} the storage elastic modulus G ′ of the core resin becomes 10 ^6.5 Pa is preferably included in the range of the general preheating temperature in the powder bed fusion bonding method. Therefore, TC ₍₆₅₎ is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 300 ° C. or lower, further preferably 100 ° C. or higher and 250 ° C. or lower, and 140 ° C. or higher and 250 ° C. or lower. More preferably, it is not higher than ° C.

Further, the temperature TS _{(65) at which} the storage elastic modulus G ′ of the shell resin becomes 10 ^6.5 Pa is a temperature at which the core resin can be easily melted by irradiation with laser light while ensuring the freedom of selection of the core resin. It is preferable to be in the range. Therefore, TS ₍₆₅₎ is preferably 100 ° C. or higher and 350 ° C. or lower, more preferably 150 ° C. or higher and 350 ° C. or lower, further preferably 150 ° C. or higher and 330 ° C. or lower, and 170 ° C. or higher and 330 ° C. or lower. It is more preferable that the temperature is not higher than 170C, and it is more preferable that the temperature is not lower than 170C and not higher than 300C.

In addition, from the viewpoint of making the shaped article after the laser light irradiation more difficult to deform, the core resin is preferably solidified in a shorter time during cooling after the laser light irradiation. From the above viewpoint, the temperature at which the core resin softens (temperature TC ₍₆₅₎ at which the storage elastic modulus G ′ becomes 10 ^6.5 Pa) and the temperature at which the core resin becomes hard enough to be deformed (storage elastic modulus G ′) It is preferable that the temperature difference with the temperature (TC ₍₇₀₎ ) at which 10 ^7.0 Pa is reached is small, specifically, | TC ₍₇₀₎ -TC ₍₆₅₎ | Is preferably 10 ° C or higher and 80 ° C or lower, more preferably 10 ° C or higher and 70 ° C or lower, further preferably 10 ° C or higher and 60 ° C or lower, more preferably 10 ° C or higher and 50 ° C or lower. More preferably.

  Here, each said storage elastic modulus can be made into the value measured by the well-known method. In this specification, the value obtained by measuring by a method using a storage modulus measurement apparatus (ARES-G2 rheometer, manufactured by TA Instruments Inc.) is defined as the storage modulus. In addition, when measuring the temperature at which the storage elastic modulus of the core resin shows a specific numerical value, viscoelasticity data may be measured according to the following procedure with the coated particles having the core-shell structure. On the other hand, in order to measure the temperature at which the storage elastic modulus of the shell resin exhibits a specific value, the core resin is removed by immersing the coated particles in a solvent that dissolves only the core resin and dissolving the core resin. And viscoelasticity data is measured with respect to the remaining shell resin according to the following procedures.

(Preparation of storage modulus measurement sample)
The core resin or shell resin that constitutes the coated particles is separated and extracted with a solvent that dissolves only one of the core resin and the shell resin, and dried to form a powder. Using a pressure molding machine (NTA Corporation, NT-100H), the obtained powder is pressed at 30 kN for 1 minute at room temperature to form a cylindrical sample having a diameter of about 8 mm and a height of about 2 mm. .

(Measurement procedure of storage modulus)
The temperature of the parallel plate of the above apparatus is adjusted to 150 ° C., the prepared cylindrical sample is heated and melted, and then a load is applied in the vertical direction so that the axial force does not exceed 10 (g weight). Then, the sample is fixed to the parallel plate. In this state, the parallel plate and the columnar sample are heated to a measurement start temperature of 250 ° C., and viscoelasticity data is measured while gradually cooling. The measured data is transferred to a computer equipped with Microsoft Windows 7 ("Windows" is a registered trademark of the company), and transferred via control, data collection and analysis software (TRIOS) operating on the computer. The value of the storage elastic modulus G ′ (Pa) at the temperature is read.

(Conditions for measuring storage modulus)
Measurement frequency: 6.28 radians / second Measurement distortion setting: The initial value is set to 0.1%, and measurement is performed in the automatic measurement mode.
Sample extension correction: Adjust in automatic measurement mode.
Measurement temperature: Slow cooling from 250 ° C. to 100 ° C. at a rate of 5 ° C. per minute.
Measurement interval: Viscoelasticity data is measured every 1 ° C.

  Here, the average particle diameter of the coated particles is preferably 2 μm or more and 210 μm or less, and more preferably 10 μm or more and 80 μm or less. When the average particle diameter of the coated particles is 2 μm or more, the thickness of each modeled object layer produced by the method for manufacturing a three-dimensional modeled object described later tends to be sufficiently thick, and a three-dimensional modeled object can be manufactured efficiently. . On the other hand, if the average particle diameter of the coated particles is 210 μm or less, a three-dimensionally shaped object having a complicated shape can be produced.

  At this time, the average particle size of the core is preferably 1 μm or more and 200 μm or less, more preferably 2 μm or more and 150 μm or less, further preferably 5 μm or more and 100 μm or less, and 5 μm or more and 70 μm or less. Is more preferably 10 μm or more and 60 μm or less. When the average particle diameter of the core is 1 μm or more, the powder material has sufficient fluidity, so that it becomes easy to handle the powder material when manufacturing the three-dimensional structure. Further, when the average particle diameter is 1 μm or more, the core resin can be easily produced, and the production cost of the powder material does not increase. When the average particle diameter is 200 μm or less, it becomes possible to produce a higher-definition three-dimensional modeled object.

  On the other hand, the thickness of the shell (the thickness of the layer made of the shell resin) is preferably 10 to 500 nm, more preferably 20 to 500 nm, still more preferably 40 to 500 nm, and more preferably 40 to 450 nm. More preferably. When the shell resin layer is composed of a plurality of particles, the average particle diameter of the particles constituting the shell resin is preferably smaller than the average particle diameter of the core resin particles, and the average particle diameter of the core resin is More preferably, it is half or less. When the thickness of the layer made of the core resin is 10 nm or more, it is difficult for the coated particles to aggregate during preheating. In addition, when the thickness is 500 nm or less, deformation such as warpage hardly occurs in the obtained molded article.

  The average particle diameter of the coated particles is a volume average particle diameter measured by a dynamic light scattering method. The volume average particle diameter can be measured with a laser diffraction particle size distribution measuring apparatus (manufactured by SYMPATEC, HELOS) equipped with a wet disperser. The average particle diameter of the core and the thickness of the shell are the thickness of the layer made of the shell resin for 10 randomly selected coated particles in an image obtained by imaging a cross section of a large number of coated particles with a TEM. Ten points are actually measured, and an average value thereof can be adopted.

  The amount of the core resin and the shell resin in the coated particles may be an amount that allows the core-shell structure to be formed. For example, the amount of the shell resin with respect to 100 parts by mass of the core resin is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less. More preferably, they are 1 mass part or more and 15 mass parts or less, More preferably, they are 1 mass part or more and 15 mass parts or less, More preferably, they are 1 mass part or more and 10 mass parts or less.

  Further, the circularity of the coated particles is preferably 0.95 or more, more preferably 0.96 or more, and further preferably 0.97 or more. When the degree of circularity of the coated particles is 0.95 or more, the volume of each coated particle tends to be uniform, and it becomes easy to form a shaped article layer in a desired shape. The circularity indicates the average circularity of the coated particles, and is a value measured using “FPIA-2100” (manufactured by Sysmex).

Specifically, the coated particles are wetted with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. Then, using “FPIA-2100”, measurement is performed at an appropriate density of 3000 to 10,000 HPF detections in a measurement condition HPF (high magnification imaging) mode. Within this range, reproducible measurement values can be obtained. The circularity is calculated by the following formula.
Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)
The average circularity is an arithmetic average value obtained by adding the circularity of each particle and dividing by the total number of particles measured.

Here, the core resin and the shell resin of the above-described coated particles are not particularly limited as long as they are resins that are softened or melted by heating, and the above-described ΔSP, TS ₍₆₅₎ , TC ₍₆₅₎ , storage elastic modulus, etc. Each can be selected in consideration. A resin that disappears by heating can be selected as the shell resin. Examples of resins applicable to the core resin and the shell resin include crystalline resins such as polyethylene, polypropylene, nylon, polyacetal, polyethylene terephthalate (PET), polyphenyl sulfide, polyether ether ketone (PEEK), and crystalline polyester. Polystyrene, polyurethane, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer (ABS), acrylic polymer, polycarbonate, ethylene-vinyl acetate copolymer (EVA), styrene-acrylonitrile copolymer (SAN), polyarylate, polyethersulfone (PES) ), Non-crystalline resins such as polyphenylene ether and polycaprolactone.

  Among these resins, it is difficult to increase the modeling accuracy of the non-crystalline resin by the conventional method, but according to the coated particles having the core-shell structure of the present embodiment, it is possible to increase the modeling accuracy. Become. From this point of view, a more useful powder material can be obtained by using an amorphous resin as the core resin material.

1-2. Other Materials As described above, the powder material may contain components other than the above-described coated particles, and examples thereof include a laser absorber and a flow agent.

1-2-1. Laser absorber From the viewpoint of more efficiently converting laser light energy into thermal energy, the powder material may further include a laser absorber. The laser absorber may be a material that absorbs a laser having a wavelength to be used and generates heat. Examples of such laser absorbers include carbon powder, nylon resin powder, pigments, and dyes. These laser absorbers may be used alone or in combination of two types.

  The amount of the laser absorber can be appropriately set within a range in which the fusion bonding of the coated particles is facilitated. For example, it can be more than 0 mass% and less than 3 mass% with respect to the total mass of the powder material.

1-2-2. Flow Agent From the viewpoint of improving the fluidity of the powder material and facilitating the handling of the powder material during the production of the three-dimensional structure, the powder material may further include a flow agent. The flow agent may be a material having a small coefficient of friction and self-lubricating properties. Examples of such flow agents include silicon dioxide and boron nitride. These flow agents may be used alone or in combination.

  The amount of the flow agent can be appropriately set within a range in which the fluidity of the powder material is improved and the melt-bonding of the coated particles having the core-shell structure is sufficiently generated, for example, with respect to the total mass of the powder material, It can be more than 0% by mass and less than 2% by mass.

2. Manufacturing method of powder material The manufacturing method of the said powder material is not restrict | limited, It can manufacture by a well-known method. For example, when the powder material contains only the above-described coated particles, the coated particles can be used as the powder material as they are. On the other hand, when the powder material includes coated particles and other materials, the powdered other materials and the coated particles can be manufactured by stirring and mixing. Hereinafter, a method for preparing the coated particles will be described.

(Method for preparing coated particles)
The aforementioned coated particles can be produced by a known method. Examples of the method for preparing the coated particles include a wet coating method in which a coating solution in which a shell resin is dissolved in particles made of a core resin is applied, or a mixture of particles made of a core resin and particles made of a shell resin. And a dry coating method in which bonding is performed by mechanical impact, and a combination of these methods. When employing the wet coating method, the coating solution may be spray-coated on the surface of the core resin, or the core resin may be immersed in the coating solution. According to the wet coating method, coated particles in which a core particle is coated with a sheet-like shell resin as shown in FIG. 1A can be obtained. On the other hand, according to the dry coating method, coated particles in which the core particles are coated with the particulate shell resin as shown in FIG. 1B can be obtained. According to the wet coating method, it is easy to form a layer made of a shell resin having a uniform thickness. Since the dry coating method does not require a drying step, the manufacturing process can be simplified.

  As described above, the core resin and the shell resin are selected in consideration of ΔSP and the storage elastic modulus. Commercially available core resins and shell resins may be used. Moreover, you may use what was prepared by superposing | polymerizing a monomer, a prepolymer, etc.

  In the case of using a commercially available resin, commercially available materials may be used in combination so that the aforementioned ΔSP and storage elastic modulus satisfy the above relationship. At this time, it is possible to keep ΔSP within the aforementioned range by confirming the SP value of each resin. ΔSP of each resin may be calculated by the method described in the above-mentioned literature, or may be specified by a cloud point titration method.

On the other hand, if a specific resin is selected as the core resin and a material having a higher Tg than the resin is selected as the shell resin, the above-described relationship between TC ₍₆₅₎ and TS ₍₆₅₎ can be easily satisfied. For example, if the core resin is selected from polyethylene, polypropylene, and polystyrene that tend to have a low Tg, and the polyether ether ketone (PEEK), polycarbonate, and acrylic polymer that tend to have a high Tg are selected as the shell resin, the above-mentioned TC It becomes possible to easily satisfy the relationship between ₍₆₅₎ and TS ₍₆₅₎ . In addition, Tg of commercially available resin is often announced by each manufacturer.

  On the other hand, when preparing a resin, the SP value of the resin can be adjusted by the structure of the resin (for example, the functional group and the number of carbons in the main chain). Depending on the type of monomer or prepolymer used, It is possible to adjust.

  The storage elastic modulus G ′ of the resin to be prepared can be controlled within a desired range by changing the average molecular weight of the resin. Specifically, if the average molecular weight of the prepared resin is increased, the storage elastic modulus G ′ of the resin is increased, and if the average molecular weight of the prepared resin is decreased, the storage elastic modulus G ′ of the resin is decreased. For each type of resin to be used, the relationship between the molecular weight and the storage elastic modulus G ′ at the preheating temperature is examined in advance, and the molecular weight of the resin to be prepared is determined by referring to the above relationship at the next resin production. Also good.

3. Next, a method for manufacturing a three-dimensional model using the above-described powder material will be described. In the manufacturing method of the three-dimensional molded item of this embodiment, it can carry out similarly to the normal powder bed fusion | bonding method except using the said powder material. Specifically, (1) a thin layer forming step for forming a thin layer made of the aforementioned powder material, (2) a preheating step for preheating the thin layer of the formed powder material, and (3) preheating A laser beam irradiation step of selectively irradiating the formed thin layer with laser light to form a shaped article layer in which the coated particles contained in the powder material are melt-bonded to each other. And a three-dimensional molded item can be manufactured by repeating a process (1)-a process (3) several times in this order, and laminating | stacking a molded article layer.

3-1. Thin layer formation process (process (1))
In this step, a thin layer of the powder material is formed. For example, the powder material supplied from the powder supply unit is laid flat on a modeling stage by a recoater. The thin layer may be formed directly on the modeling stage, or may be formed so as to be in contact with the already spread powder material or the already formed modeling layer.

  The thickness of the thin layer is the same as the thickness of the desired shaped article layer. Although the thickness of a thin layer can be arbitrarily set according to the precision of the three-dimensional molded item to manufacture, it is 0.01 mm or more and 0.30 mm or less normally. By setting the thickness of the thin layer to 0.01 mm or more, it is possible to spread a uniform powder. In addition, by setting the thickness of the thin layer to 0.30 mm or less, the energy of the laser beam is conducted to the lower part of the thin layer, and the coated particles contained in the powder material constituting the thin layer are spread over the entire thickness direction. It can be sufficiently melt-bonded. From the above viewpoint, the thickness of the thin layer is more preferably 0.01 mm or more and 0.10 mm or less. In addition, from the viewpoint of more sufficiently melting and bonding the coated particles throughout the thickness direction of the thin layer and making it less likely to cause cracks in the shaped object layer, the thickness of the thin layer is determined by the beam spot diameter of the laser beam described later. It is preferable to set the difference of 0.10 mm or less.

3-2. Preheating process (process (2))
In this step, the thin layer of the formed powder material is preheated. The preheating temperature is determined by the surface temperature of the thin layer after the preheating from the viewpoint of suppressing the pre-heated powder material from re-dissolving and distorting the modeling layer and reducing the modeling accuracy. It is preferable to set the storage elastic modulus G ′ so as to be 5 ° C. or more and 50 ° C. or less higher than the temperature TC _{(65) at} which the storage elastic modulus G ′ becomes 10 ^6.5 Pa. Further, it is preferable to set the temperature so that the storage elastic modulus G′c of the core resin of the coated particles is 10 ⁶ Pa or less and the storage elastic modulus G ′s of the shell resin is 10 ⁸ Pa or more. The preheating temperature is preferably 50 ° C or higher and 300 ° C or lower, more preferably 100 ° C or higher and 300 ° C or lower, further preferably 100 ° C or higher and 250 ° C or lower, and 140 ° C or higher and 250 ° C or lower. More preferably it is. At this time, the heating time is preferably 1 to 30 seconds, more preferably 5 to 20 seconds. By setting the heating temperature and the heating time in the above ranges, the core resin in the coated particles can be sufficiently softened or dissolved, and a three-dimensional structure can be manufactured with a small amount of laser energy.

3-3. Laser light irradiation process (process (3))
In this step, laser light is selectively irradiated to a position where a shaped article layer is to be formed in the preheated thin layer, and the coated particles at the irradiated position are melt-bonded. The melt-bonded coated particles are melted together with adjacent powders to form a melt-bonded body, which becomes a shaped article layer. At this time, since the coated particles that have received the energy of the laser beam are also melt-bonded to the already formed object layer, adhesion between adjacent layers also occurs.

What is necessary is just to set the wavelength of a laser beam within the range of the wavelength which shell resin absorbs. At this time, it is preferable to reduce the difference between the wavelength of the laser beam and the wavelength at which the absorption rate of the shell resin is the highest. However, since the resin generally absorbs light in various wavelength ranges, CO 2 It is preferable to use laser light having a wide wavelength band such as _two lasers. For example, the wavelength of the laser beam can be, for example, not less than 0.8 μm and not more than 12 μm.

The output condition of the laser beam may be set so that the storage elastic modulus G ′ of the core resin is 10 ⁶ (Pa) or less.

  For example, the power at the time of laser beam output may be set within a range where the shell resin is sufficiently melt-bonded at a laser beam scanning speed described later. Specifically, it can be set to 5.0 W or more and 60 W or less. From the viewpoint of reducing the energy of the laser beam, reducing the manufacturing cost, and simplifying the configuration of the manufacturing apparatus, the power at the output of the laser beam is preferably 30 W or less, preferably 20 W or less. More preferably.

  The scanning speed of the laser light may be set within a range that does not increase the manufacturing cost and does not excessively complicate the apparatus configuration. Specifically, it is preferably 1 mm / second to 100 mm / second, more preferably 1 mm / second to 80 mm / second, further preferably 2 mm / second to 80 mm / second, and more preferably 3 mm. / Mm or more and 80 mm / second or less is more preferable, and 3 mm / second or more and 50 mm / second or less is further preferable.

  The beam diameter of the laser light can be appropriately set according to the accuracy of the three-dimensional structure to be manufactured.

3-4. About repetition of process (1)-process (3) In the case of manufacture of a three-dimensional molded item, the above-mentioned process (1)-process (3) are repeated arbitrary times in this order. Thereby, a modeling object layer is laminated | stacked and a desired three-dimensional modeling object will be obtained.

3-5. Others From the viewpoint of preventing the strength of the three-dimensional structure from being lowered due to oxidation of the coated particles in the melt bond, at least step (3) is preferably performed under reduced pressure or in an inert gas atmosphere. The pressure when reducing the pressure is preferably 10 ⁻² Pa or less, and more preferably 10 ⁻³ Pa or less. Examples of the inert gas that can be used in the present embodiment include nitrogen gas and rare gas. Among these inert gases, nitrogen (N ₂ ) gas, helium (He) gas, or argon (Ar) gas is preferable from the viewpoint of availability. From the viewpoint of simplifying the production process, it is preferable to perform all of the steps (1) to (3) under reduced pressure or in an inert gas atmosphere.

4). Three-dimensional modeling apparatus The three-dimensional modeling apparatus which can be used for the manufacturing method of the said three-dimensional molded item is demonstrated. The three-dimensional modeling apparatus that can be used in the present embodiment can have the same configuration as a known three-dimensional modeling apparatus. Specifically, as shown in the schematic side view of FIG. 2, the three-dimensional modeling apparatus 200 according to the present embodiment includes a modeling stage 210 located in the opening, and a thin film forming unit 220 for forming a thin film made of a powder material. , A preheating unit 230 for preheating the thin film, a laser irradiation unit 240 for irradiating the thin film with laser light, a stage support unit 250 for supporting the modeling stage 210 by changing the position in the vertical direction, and supporting each of the above parts The base 290 is provided.

  On the other hand, the main part of the control system of the three-dimensional modeling apparatus 200 is shown in FIG. As shown in FIG. 3, the three-dimensional modeling apparatus 200 controls the thin film forming unit 220, the preheating unit 230, the laser irradiation unit 240, and the stage support unit 250 to form and stack a modeled object, Display unit 270 for displaying various types of information, operation unit 275 including a pointing device for receiving instructions from the user, storage unit 280 for storing various types of information including control programs executed by control unit 260, and external You may provide the data input part 285 containing the interface etc. for transmitting / receiving various information, such as three-dimensional modeling data, between apparatuses. The three-dimensional modeling apparatus 200 may include a temperature measuring device 235 that measures the surface temperature of the thin layer formed on the modeling stage 210. The three-dimensional modeling apparatus 200 may be connected to a computer device 300 for generating three-dimensional modeling data.

  The modeling stage 210 is controlled to be movable up and down, and on the modeling stage 210, a thin layer is formed by the thin film forming unit 220, a thin layer is preheated by the preheating unit 230, and a laser beam is irradiated by the laser irradiation unit 240. Done. And the modeling thing formed by these is laminated | stacked, and a three-dimensional modeling thing is formed.

  The thin film forming unit 220 includes a powder material storage unit 221a that stores a powder material, a powder supply unit 221 that is provided at the bottom of the powder material storage unit 221a, and a supply piston 221b that moves up and down in the opening. The supplied powder material can be laid flat on the modeling stage 210 to form a recoater 222a that forms a thin layer of the powder material. In the present embodiment, the upper surface of the opening of the powder material storage unit 221a is disposed on substantially the same plane as the upper surface of the opening for moving the modeling stage 210 up and down (for forming a three-dimensional modeled object).

  The powder supply unit 221 discharges a powder material storage unit (not shown) provided vertically above the modeling stage 210 and the powder material stored in the powder material storage unit in desired amounts. It is good also as a structure provided with the nozzle (not shown) for this. In this case, a thin layer can be formed by uniformly discharging the powder material from the nozzle onto the modeling stage 210.

  The preheating part 230 should just be what can heat the area | region which should form a molded article layer among the surfaces of a thin layer, and can maintain the temperature. In the present embodiment, the preheating unit 230 heats the first heater 231 that can heat the surface of the thin layer formed on the modeling stage 210 and the powder material before being supplied onto the modeling stage. The heater 232 is provided, but only one of them may be provided. Moreover, the structure which selectively heats the area | region which should form the said molded article layer may be sufficient as the preheating part 230. FIG. Moreover, the structure which heats the whole inside apparatus previously and controls the surface of the said thin film to predetermined temperature may be sufficient.

  The temperature measuring device 235 may be any device that can measure the surface temperature of a thin layer, particularly the surface temperature of a region where a shaped article layer is to be formed, without contact, and may be, for example, an infrared sensor or an optical pyrometer.

The laser irradiation unit 240 can include a laser light source 241 and a galvano mirror 242a. The laser irradiation unit 240 may include a laser window 243 that transmits laser light and a lens (not shown) for adjusting the focal length of the laser light to the surface of the thin layer. The laser light source 241 may be a light source that emits the laser light having the wavelength with the output. Examples of the laser light source 241 include a YAG laser light source, a fiber laser light source, and a CO ₂ laser light source. The galvanometer mirror 242a may include an X mirror that reflects the laser light emitted from the laser light source 241 and scans the laser light in the X direction and a Y mirror that scans in the Y direction. The laser window 243 may be made of a material that transmits laser light.

  The stage support unit 250 only needs to variably support the vertical position of the modeling stage 210. That is, the modeling stage 210 is configured to be precisely movable in the vertical direction by the stage support portion 250. Various configurations can be adopted as the stage support portion 250. For example, the stage support portion 250 is related to a holding member that holds the modeling stage 210, a guide member that guides the holding member in the vertical direction, and a screw hole provided in the guide member. It can be constituted by a ball screw or the like to be combined.

  The control unit 260 includes a hardware processor such as a central processing unit, and controls the overall operation of the 3D modeling apparatus 200 during the modeling operation of the 3D model.

  Moreover, the control part 260 may be comprised so that the three-dimensional modeling data which the data input part 285 acquired from the computer apparatus 300 may be converted into several slice data sliced thinly about the lamination direction of a modeling object layer, for example. Slice data is modeling data of each modeled object layer for modeling a three-dimensional modeled object. The thickness of the slice data, that is, the thickness of the modeled object layer matches the distance (lamination pitch) corresponding to the thickness of one layer of the modeled object layer.

  Display unit 270 can be, for example, a liquid crystal display or a monitor.

  The operation unit 275 may include a pointing device such as a keyboard and a mouse, and may include various operation keys such as a numeric keypad, an execution key, and a start key.

  The storage unit 280 can include various storage media such as a ROM, a RAM, a magnetic disk, an HDD, and an SSD.

  The three-dimensional modeling apparatus 200 receives the control of the control unit 260 and decompresses the inside of the apparatus. The decompression unit (not shown) such as a decompression pump or the control unit 260 controls the inert gas into the apparatus. You may provide the inert gas supply part (not shown) to supply.

  Here, the three-dimensional modeling method using the three-dimensional modeling apparatus 200 of the present embodiment will be specifically described. The control unit 260 converts the three-dimensional modeling data acquired from the computer apparatus 300 by the data input unit 285 into a plurality of slice data sliced thinly in the stacking direction of the modeled object layer. Thereafter, the control unit 260 controls the following operations in the three-dimensional modeling apparatus 200.

  The powder supply unit 221 drives a motor and a drive mechanism (both not shown) according to the supply information output from the control unit 260, moves the supply piston upward (in the direction of the arrow in FIG. 2), and the modeling Extrude the powder material on the same horizontal plane as the stage.

  Thereafter, the recoater driving unit 222 moves the recoater 222a in the horizontal direction (arrow direction in the figure) according to the thin film formation information output from the control unit 260, conveys the powder material to the modeling stage 210, and the thin layer The powder material is pressed so that the thickness becomes the thickness of one layer of the shaped article layer.

The preheating unit 230 heats the surface of the thin layer formed in accordance with the temperature information output from the control unit 260 or the entire apparatus. The temperature information is stored in the control unit 260 based on, for example, data on the temperature TC ( ₆₅ ) at which the storage elastic modulus G ′ of the material constituting the core resin, which is input from the data input unit 285, becomes 10 ^6.5 Pa. It can be used as information for heating the surface of the thin layer to a temperature drawn from the portion 280 so that the difference from the above temperature is 5 ° C. or more and 50 ° C. or less. The preheating unit 230 may start the heating after the thin layer is formed, or the portion corresponding to the surface of the thin layer to be formed before the thin layer is formed or heating in the apparatus. May be.

  After that, the laser irradiation unit 240 emits laser light from the laser light source 241 in accordance with the laser irradiation information output from the control unit 260, in accordance with the area constituting the three-dimensional object in each slice data on the thin film, The galvano mirror driving unit 242 drives the galvano mirror 242a to scan the laser beam. The coated particles contained in the powder material are melt-bonded by the irradiation of the laser beam, and a shaped article layer is formed.

  Thereafter, the stage support unit 250 drives a motor and a drive mechanism (both not shown) according to the position control information output from the control unit 260, and moves the modeling stage 210 vertically downward (in the direction of the arrow in the drawing). )

  The display unit 270 displays various information and messages that should be recognized by the user under the control of the control unit 260 as necessary. The operation unit 275 receives various input operations by the user and outputs an operation signal corresponding to the input operation to the control unit 260. For example, a virtual three-dimensional object to be formed is displayed on the display unit 270 to check whether or not a desired shape is formed. If the desired shape is not formed, the operation unit 275 may be modified. Good.

  The control unit 260 stores data in the storage unit 280 or extracts data from the storage unit 280 as necessary.

In addition, the control part 260 receives the information of the temperature of the area | region which should form a modeling object layer from the temperature measuring device 235 among the surfaces of a thin layer, the temperature of the area | region which should form the said modeling object layer, and the said core resin Preheating so that the difference from the temperature TC ( ₆₅ ) at which the storage elastic modulus G ′ of the material constituting the material becomes 10 ^6.5 Pa is 5 ° C. or more and 50 ° C. or less, preferably 5 ° C. or more and 30 ° C. or less. The heating by the unit 230 may be controlled.

  By repeating these operations, the modeled object layer is laminated and a three-dimensional modeled object is manufactured.

  In the following, specific examples of the present invention will be described. These examples do not limit the scope of the present invention.

1. 1. Production of powder material 1-1. Preparation of raw materials Resins shown in Table 1 below were prepared as materials for the core resin and the shell resin. In addition, when the average particle diameter of commercially available resin is larger than the numerical value of Table 1, it measures with the laser diffraction type particle size distribution measuring apparatus (Sympathetic (SYMPATEC) company make, HELOS) provided with the wet disperser. The resin fine particles were pulverized by a mechanical pulverization method until the average particle diameter reached the value shown in Table 1.

1-2. Preparation of powder material (1) Preparation of powder material 1 740 parts by mass of PA12 was introduced into Spiraflow (SFC-MINI, manufactured by Freund Sangyo Co., Ltd.), the supply air temperature was 50 ° C., the static pressure inside the layer was 1.8 kPa, and the exhaust static After making the fluidized state under the conditions of pressure 2.1 kPa, rotor rotational speed 400 rpm, agitator rotational speed 600 rpm, a solution prepared by dissolving 50 parts by mass of PAR separately prepared in 1000 parts by mass of tetrahydrofuran (THF) was 4 g / min. The powder material 1 containing the coated particles was obtained by spraying the solution into the layer from the spray nozzle at a speed of 90 mm and spraying the solution from the spray nozzle for 90 minutes.

(2) Preparation of powder materials 2-7, 9, and 10 Powder materials 2-7, 9, and containing coated particles, in the same manner as powder material 1 except that the types of resins are the combinations shown in Table 2. 10 was obtained. Powder materials 2 and 3 were prepared in the same manner as powder material 1 except that the spraying time of the PAR solution was 18 minutes and 164 minutes.

(3) Preparation of powder material 8 PA12 was directly used as powder material 8.

2. Evaluation About the obtained powder material and the three-dimensional molded item obtained from the said powder material, it evaluated as follows.

2-1. Evaluation of powder material (1) Storage elastic modulus of core resin and shell resin The storage elastic modulus of the core resin and shell resin shown in Table 2 is a storage elastic modulus measuring device (ARES-G2 manufactured by TA Instruments). It is a value measured by the following method using a rheometer.

・ Measurement method of storage modulus (Preparation of sample)
Using a pressure molding machine (NT-100H, manufactured by NP System Co., Ltd.), the resin was pressurized at 30 kN for 1 minute at room temperature to mold the resin into a cylindrical sample having a diameter of about 8 mm and a height of about 2 mm.

(Measurement procedure)
The temperature of the parallel plate of the apparatus was adjusted to 150 ° C., and the columnar sample prepared as described above was heated and melted. Thereafter, a load was applied in the vertical direction so that the axial force did not exceed 10 (g weight), and the sample was fixed to the parallel plate. In this state, the parallel plate and the cylindrical sample were heated to a measurement start temperature of 250 ° C., and viscoelasticity data was measured while gradually cooling. The measured data is transferred to a computer equipped with Microsoft Windows 7 and transferred through control, data collection and analysis software (TRIOS) operating on the computer, and the storage elastic modulus G ′ is 10 ^6.5 ( The temperature TC ₍₆₅₎ or TS ₍₆₅₎ to become Pa) was specified.

(Measurement condition)
Measurement frequency: 6.28 radians / second.
Measurement strain setting: The initial value was set to 0.1%, and measurement was performed in automatic measurement mode.
Sample extension correction: Adjusted in automatic measurement mode.
Measurement temperature: Slow cooling from 250 ° C. to 100 ° C. at a rate of 5 ° C. per minute.
Measurement interval: Viscoelasticity data was measured every 1 ° C.

(2) Thickness of layer made of shell resin The coated particles were dispersed in a photocurable resin (D-800 manufactured by JEOL Ltd.) and then photocured to form a block. Using a microtome equipped with diamond teeth, a flaky sample having a thickness of 100 to 200 nm was cut out from the block and placed on a grid with a support film for transmission electron microscope observation. The grid was placed on a scanning transmission electron microscope (JSM-7401F, manufactured by JEOL Ltd.), and a bright field image was taken under the following conditions.

(Imaging method)
Acceleration voltage: 30 kV
Magnification: 10,000 times

  A cross section of a large number of coated particles is imaged with a TEM, the interface between the core resin and the shell resin of 10 coated particles randomly selected from the obtained images is confirmed, and the thickness of the shell resin of each coated particle is measured. And the average of those was calculated | required and it was set as the average thickness of shell resin.

2-2. Evaluation of 3D modeling object (1) Production of 3D modeling object Powder material 1-10 is spread on the modeling stage installed on the hot plate to form a thin layer with a thickness of 0.1 mm, and the temperature of the hot plate is adjusted. Thus, each was heated to the preheating temperature described in Table 2. This thin layer was irradiated with laser light in a range of 15 mm long × 20 mm wide from a 50 WCO ₂ laser equipped with a galvanometer scanner for YAG wavelength under the following conditions to produce a shaped article layer. The above steps were repeated 10 times, and 10-layer laminated three-dimensional shaped objects were respectively produced.

[Laser output conditions]
Laser output: 50W
Laser light wavelength: 10 μm
Beam diameter: 170 μm on the surface of the thin layer

[Laser beam scanning conditions]
Scanning speed: 2000mm / sec
Number of lines: 1 line

[Ambient atmosphere]
Temperature: Preheating temperature Gas: Nitrogen (N ₂ ) 100%

(2) Evaluation of melting characteristics About the three-dimensional molded object produced by the above-mentioned method, it imaged by SEM (scanning electron microscope, brand name S-3500N made by Hitachi Ltd.) about arbitrary ranges. Obtain the ratio of the number of coated particles that were sintered or melt-bonded with the adjacent powder to the total number of coated particles that can be confirmed in the obtained image, and evaluate the state of sintering or melting according to the following criteria did. The photographing conditions of a commercially available scanning electron microscope are as follows.

Vacuum mode: Low vacuum mode Acceleration voltage: 5 kV
Magnification: 250 times Time from the start of electron irradiation to the start of imaging: 3 minutes Sample: Sputtered Sample stage: Made of aluminum, grounded

Further, the melting characteristics were evaluated according to the following criteria.
○: All coated particles found in the SEM image were sintered or melt-bonded with the adjacent powder. Δ: 50% or more and less than 100% of the coated particles found in the SEM image were the adjacent powder. Sintered or melt bonded X: Less than 50% of the powder material in the SEM image was sintered or melt bonded to the adjacent powder

(3) Aggregation test 1 g of each of powder materials 1 to 10 was weighed into a 20 cc glass sample bottle and left on a hot plate maintained at a predetermined temperature for 10 minutes. After standing, the temperature was returned to room temperature, and then the powder material was transferred onto a metal mesh sieve having an opening diameter of 2 mm, vibration was applied for 20 seconds, and the weight of the powder material remaining on the sieve was measured. The above operation was repeated while changing the set temperature of the hot plate, and the temperature of the first hot plate where the powder material having a weight of 10% or more remained was defined as the aggregation occurrence temperature.

As shown in Table 2 above, the absolute value ΔSP of the difference between the SP value of the core resin and the SP value of the shell resin is 2.5 (J / cm ³ ) ^{1/2 to} 7.0 (J / cm ³ ) When ^1/2 was satisfied (powder materials 1 to 7), the aggregation generation temperature was higher than the preheating temperature, and no aggregation occurred during the preheating. Also, the melting characteristics were all good. Since the preheating temperature could be increased to 170 ° C. or higher, each powder material could be sufficiently sintered with the same amount of laser energy.

  On the other hand, when ΔSP was too small, the shell resin was dissolved in the melted core resin during the preheating, and the aggregation occurrence temperature became lower than the preheating temperature. Moreover, since aggregation occurred, the powder itself solidified and could not be formed (powder material 9). On the other hand, when ΔSP was too large, the melt bonding of the coated particles did not proceed well, and a molded article could not be obtained well (powder material 10). This is presumably because the core resin and the shell resin were phase-separated when the powder material was irradiated with laser light. Further, when particles having no core-shell structure were used, it was not possible to sufficiently melt or sinter with the same amount of laser energy as in the examples (powder material 8).

  This application claims the priority based on Japanese Patent Application No. 2006-058643 of an application on March 23, 2016. The contents described in the application specification and the drawings are all incorporated herein.

  According to the method and apparatus of the present invention, more accurate modeling can be achieved with a small amount of laser energy by the powder bed fusion bonding method. Therefore, the present invention is considered to contribute to further spread of the powder bed fusion bonding method.

DESCRIPTION OF SYMBOLS 100 Coated particle 101 Core particle 102 Shell resin 200 Three-dimensional modeling apparatus 210 Modeling stage 220 Thin film formation part 221 Powder supply part 222 Recoater drive part 222a Recoater 230 Preheating part 231 1st heater 232 2nd heater 235 Temperature measuring device 240 Laser Irradiation unit 241 Laser light source 242 Galvano mirror driving unit 242a Galvano mirror 243 Laser window 250 Stage support unit 260 Control unit 270 Display unit 275 Operation unit 280 Storage unit 290 Base 285 Data input unit 300 Computer device

Claims (6)

The formation of a thin layer of powder material containing coated particles, preheating of the thin layer, and selective laser light irradiation to the thin layer are repeated, and a plurality of shaped layers in which the coated particles are melt-bonded are laminated. A powder material used in a method of manufacturing a three-dimensional structure,
The coated particles include a core resin and a shell resin that coats the core resin,
The absolute value of the difference between the SP value of the core resin and the SP value of the shell resin is 2.5 (J / cm ³ ) ^{1/2 to} 7.0 (J / cm ³ ) ^1/2 ,
The storage elastic modulus of the shell resin G 'is ^{10 6.5} Pa Temperature _{TS (65)} has a storage modulus G of the core resin' is higher than the temperature _{TC (65)} to become ^{10 6.5} Pa,
Powder material. The storage elastic modulus of the shell resin G 'is the temperature _{TS (65)} to become ^{10 6.5} Pa, the storage modulus G of the core resin' is the difference between the temperature _{TC (65)} to become ^{10 6.5} Pa 5 ° C or higher and 75 ° C or lower,
The powder material according to claim 1. In the coated particles, the thickness of the layer containing the shell resin that coats the core resin is 10 to 500 nm.
The powder material according to claim 1 or 2. The degree of circularity of the coated particles is 0.95 or more,
The powder material as described in any one of Claims 1-3. A thin layer forming step of forming a thin layer made of the powder material according to any one of claims 1 to 4,
A preheating step of preheating the thin layer;
A laser beam irradiation step of selectively irradiating the preheated thin layer with a laser beam to form a shaped article layer in which the coated particles are melt-bonded;
Including
The thin layer forming step, the preliminary heating step, and the laser light irradiation step are repeated a plurality of times in this order, and the three-dimensional object is formed by laminating the object layer,
Manufacturing method of a three-dimensional molded item. The preheating temperature is a temperature at which the storage elastic modulus G′c of the core resin of the coated particles is 10 ⁶ Pa or less and the storage elastic modulus G ′s of the shell resin is 10 ⁸ Pa or more.
The manufacturing method of the three-dimensional molded item of Claim 5.

Images