JP7457925B2 - Powder composition, method for producing a three-dimensional object by powder bed fusion bonding method using the powder composition, and three-dimensional object - Google Patents

Description

The present invention relates to a three-dimensional structure obtained by a powder bed fusion bonding method, a powder composition suitably used to obtain the three-dimensional structure, and a method for manufacturing a three-dimensional structure using the powder composition. .

BACKGROUND ART Material extrusion methods, powder bed fusion bonding methods, liquid bath photopolymerization methods, sheet lamination methods, and the like are known as techniques for manufacturing three-dimensional structures (hereinafter sometimes referred to as "modeled objects"). Among these, in the powder bed fusion bonding method, after a layer of powder is provided, a position corresponding to the cross section of the object is selectively melted, and these layers are bonded and laminated to form a three-dimensional object. Here, methods for selectively melting the powder include a selective laser sintering method using a laser, a selective absorption sintering method using a melting aid, and a selective suppression sintering method that masks areas that are not to be melted. There is. The powder bed fusion bonding method has the advantage of not requiring a support member during modeling, which is suitable for precision modeling compared to other modeling methods.

The three-dimensional objects obtained by the above method take advantage of their good mechanical properties and dimensional accuracy, and can be used for mobility applications such as automobiles, aviation, and space; medical applications such as prosthetics, orthoses, hearing aids, and catheters; sports applications; It is being considered for use in a variety of fields, including electrical and electronic materials. Among these, mobility applications require high heat resistance and elastic modulus, so resin materials containing reinforcing materials are often used, and similar characteristics are required for three-dimensional objects.

In response to such market demands, Patent Document 1 discloses a three-dimensional structure in which glass beads are blended into irregularly shaped powder of polyamide 11 or polyamide 12, and which has a higher elastic modulus than polyamide powder alone. has been done. Patent Document 2 discloses a three-dimensional structure that has high elastic modulus and heat resistance by blending predetermined glass fibers and a powder flow agent with polyamide powder.

Japanese Patent Application Publication No. 2008-266645 JP 2020-536153 A

However, in the technique of Patent Document 1, since the polyamide powder has an irregular shape and insufficient fluidity, it is not possible to incorporate a large amount of reinforcing material, and the modulus of elasticity of the obtained molded product is less than 3000 MPa, and is not higher than 3500 MPa. This was insufficient for the use of the present invention which requires an elastic modulus of .

The technology in Patent Document 2 had problems with the powder not filling sufficiently when glass fibers were added, with insufficient fluidity when short glass fibers were used, and with the glass fibers becoming tangled and reducing fluidity when the powder used in the molding was recycled.

Therefore, the present invention provides a powder composition that contains polyamide powder and a reinforcing material but has high fluidity and maintains good fluidity even when recycled, and the powder composition is applied to three-dimensional modeling. In particular, the object is to provide a shaped article that is free from warpage and has a high elastic modulus.

In order to solve the above problems, the present invention has the following configuration.
(1) A powder composition containing a polyamide powder (A) and an inorganic reinforcing material (B), wherein the D50 particle size of the polyamide powder (A) is 1 μm or more and 100 μm or less, and the inorganic reinforcing material (B) is The average major axis diameter is 10 μm or more and 120 μm or less, and the average major axis diameter/average minor axis diameter is 2 or more and 12 or less, and the content X (B) of the inorganic reinforcing material (B) with respect to the total weight of the powder composition is It is 5% by weight or more and 60% by weight or less, and when the true density T (A) of the polyamide powder (A), the true density T (B) of the inorganic reinforcing material (B), and the bulk density D of the powder composition, the coarse A powder composition characterized in that the filling rate D/{T(A)×(100−X(B))/100+T(B)×X(B)/100} is 0.40 or more and 0.70 or less .
(2) The powder composition according to (1), wherein the flow aid (C) is contained in an amount of 0.01% by weight or more and 2.0% by weight or less based on the total weight of the powder composition.
(3) The powder composition according to (2), wherein the flow aid (C) has a D50 particle size of 100 nm or more and 300 nm or less.
(4) The powder composition according to (2) or (3), wherein the flow aid (C) is silica.
(5) The powder composition according to any one of (1) to (4), wherein the inorganic reinforcing material (B) has an average major axis diameter of 30 μm or more and 90 μm or less.
(6) The powder composition according to any one of (1) to (5), wherein the inorganic reinforcing material (B) is glass fiber and/or carbon fiber .
(7) The powder composition according to any one of (1) to (6), wherein the polyamide powder (A) has a sphericity of 80 or more and 100 or less.
(8) The powder composition according to any one of (1) to (7), wherein when a three-dimensional structure is manufactured by a powder bed fusion bonding method, the X-direction elastic modulus of the structure is 3500 MPa or more.
(9) Any one of (1) to (8), where the deflection temperature under load measured at a load of 0.45 MPa is 150°C or higher when a three-dimensional structure is manufactured by the powder bed fusion bonding method. Powder composition as described.
(10) A method for producing a three-dimensional structure by a powder bed fusion bonding method using the powder composition according to any one of (1) to (9).
(11) A three-dimensional structure obtained by a powder bed fusion bonding method, with a surface roughness of 20 μm or less, an X-direction elastic modulus of 3500 MPa or more, and an average spherical equivalent diameter of pores observed by X-ray CT measurement. A three-dimensional structure whose diameter is 1 μm or more and 100 μm or less.
(12) The three-dimensional structure according to (11), wherein the pores observed by X-ray CT measurement are 0.1% by volume or more and 10% by volume or less.

According to the present invention, there is provided a powder composition that contains polyamide powder and a reinforcing material but has high fluidity and maintains good fluidity even when recycled, and the powder composition is applied to three-dimensional modeling. At the same time, it is possible to obtain a shaped article that is free from warpage and has a high elastic modulus.

FIG. 1 is a schematic diagram showing an example of a three-dimensional structure manufacturing apparatus according to the present invention. 2 is a scanning electron micrograph of the powder composition obtained in Example 2.

The present invention will be described in detail below.
Conventionally, the elastic modulus of a three-dimensional object depends on the amount and shape of the reinforcing material contained in the raw material powder composition. In order to create a composition that can produce an object with a high elastic modulus, it is necessary to mix in a reinforcing material with a certain fiber length or longer. However, due to factors such as agglomeration of the reinforcing material, recycling becomes difficult, and it has not been possible to achieve both elastic modulus and recyclability.

However, even with powder compositions that can yield three-dimensional objects with a high elastic modulus of 3,500 MPa or more, if the polyamide powder and reinforcing material meet certain conditions, they will maintain high fluidity even when recycled, When applied to three-dimensional modeling, it is possible to obtain objects with high elastic modulus. Furthermore, surprisingly, it has been found that by mechanically suppressing crystallization shrinkage during the formation of a three-dimensional model, a model with no warpage and excellent dimensional accuracy can be obtained. Ta. As a further preferred embodiment, it has been found that by applying polyamide powder with a sphericity of 80 or more, it is possible to obtain a three-dimensional structure with high surface smoothness.

That is, the powder composition of the present invention contains a polyamide powder (A) and an inorganic reinforcing material (B), the D50 particle size of (A) is 1 μm or more and 100 μm or less, and the average major axis diameter of (B) is is 10 μm or more and 120 μm or less, the average major axis diameter/average minor axis diameter is 2 or more and 12 or less, and the content X (B) of the above (B) is 5% by weight or more and 60% by weight or less based on the total weight of the powder composition. When the true density T(A) of the polyamide powder (A), the true density T(B) of the inorganic reinforcement material (B), and the bulk density D of the powder composition, the rough filling rate D/{T(A )×(100−X(B))/100+T(B)×X(B)/100} is 0.40 or more and 0.70 or less.

The powder composition of the present invention will be explained below.
The powder composition in the present invention includes a polyamide powder composed of polyamide having a structure containing an amide group. Specific examples of such polyamides include polycaproamide (polyamide 6), polyundecamide (polyamide 11), polylauramide (polyamide 12), polyhexamethylene adipamide (polyamide 66), and polydecamethylene polymer. Bacamide (Polyamide 1010), Polydodecamethylene Sebamide (Polyamide 1012), Polydodecamethylene Dodecamide (Polyamide 1212), Polyhexamethylene Sebaamide (Polyamide 610), Polyhexamethylene Dodecamide (Polyamide 612), Poly Decamethylene adipamide (Polyamide 106), Polydodecamethylene adipamide (Polyamide 126), Polyhexamethylene terephthalamide (Polyamide 6T), Polydecamethylene terephthalamide (Polyamide 10T), Polydodecamethylene terephthalamide (Polyamide 12T) , polycaproamide/polyhexamethylene adipamide copolymer (polyamide 6/66), polycaproamide/polylauramide copolymer (polyamide 6/12), and the like. Among them, polycaproamide (polyamide 6), polyundecamide (polyamide 11), polylauramide (polyamide 12), polyhexamethylene adipamide (polyamide 66), Polydecamethylene sebaamide (polyamide 1010), polydodecamethylene sebaamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sebaamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), etc. In addition, polycaproamide (polyamide 6), polyundecamide (polyamide 11), polylauramide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polyamide Particularly preferred are hexamethylene sebamide (polyamide 610), polydecamethylene sebamide (polyamide 1010), and polydodecamethylene sebamide (polyamide 1012). Among these, polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), and polyhexamethylene sebamide (polyamide 610) are extremely preferred in terms of heat resistance during molding.

The polyamide may be copolymerized to the extent that the effects of the present invention are not impaired. As the copolymerizable component, an elastomer component such as polyolefin or polyalkylene glycol that imparts flexibility, and a rigid aromatic component that improves heat resistance and strength can be selected as appropriate. Furthermore, as will be described later, a copolymerization component that adjusts the end groups may be used in order to reuse the polymer powder by a powder bed fusion bonding method. Examples of such copolymerization components include monocarboxylic acids such as acetic acid, hexanoic acid, lauric acid, and benzoic acid, and monoamines such as hexylamine, octylamine, and aniline.

The weight average molecular weight of the polyamide is preferably in the range of 10,000 to 1,000,000. The higher the weight average molecular weight, the slower the crystallization rate, and the more warping caused by crystallization during modeling can be suppressed. Therefore, the lower limit is preferably 20,000 or more, more preferably 30,000 or more, and even more preferably 40,000 or more. It is preferably 45,000 or more, particularly preferably 50,000 or more, and most preferably 50,000 or more. If the molecular weight is too high, the viscosity will be high and the dispersibility and uniformity of the reinforcing material during modeling will deteriorate, so the upper limit is preferably 700,000 or less, more preferably 500,000 or less, and even more preferably 300,000 or less. , 200,000 or less is particularly preferred, and 100,000 or less is most preferred.

Note that the weight average molecular weight of the polyamide constituting the polyamide powder refers to the value obtained by measuring the weight average molecular weight by gel permeation chromatography using hexafluoroisopropanol as a solvent and converting it into polymethyl methacrylate.

The polyamide powder composition of the present invention may contain other ingredients as long as the present invention is not impaired. Examples of compounding agents include antioxidants and heat-resistant stabilizers in order to suppress thermal deterioration due to heating during molding using the powder bed fusion bonding method. Examples of the antioxidant and heat stabilizer include hindered phenol, hydroquinone, phosphites, substituted products thereof, phosphites, hypophosphites, and the like. Other products include pigments and dyes for coloring, plasticizers for adjusting viscosity, flow aids for improving fluidity, antistatic agents for adding functionality, flame retardants, carbon black, silica, titanium dioxide, potassium titanate, Examples include fillers such as glass fiber, glass beads, carbon fiber, and cellulose nanofiber. Known materials can be used for these materials, and they may be present either inside or outside the polyamide powder.

The D50 particle size of the polyamide powder of the present invention is in the range of 1 to 100 μm. If the D50 particle size exceeds 100 μm, the particle size will exceed the stacking height and the surface will become rough. If the D50 particle size is less than 1 μm, the particles will be so fine that they will easily adhere to a recoater or the like during molding, making it impossible to raise the temperature of the molding chamber to the required temperature. The upper limit of the D50 particle size of the polyamide powder is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less. The lower limit is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

The D50 particle size of the polyamide powder is the particle size (D50 particle size) at which the cumulative frequency from the small particle size side of the particle size distribution measured by a laser diffraction particle size distribution meter is 50%.

The particle size distribution of the polyamide powder is expressed as D90/D10, which is the ratio of D90 to D10 in the particle size distribution, and is preferably less than 5.0. A narrower particle size distribution is preferable because it eliminates differences in melting properties during molding due to differences in particle size, and also makes it easier to uniformly disperse inorganic reinforcing materials, resulting in a homogeneous molded product. Therefore, D90/D10 is more preferably less than 4.0, even more preferably less than 3.0, and particularly preferably less than 2.0. The lower limit is theoretically 1.0.

D90/D10, which indicates the particle size distribution of the polyamide powder in the present invention, is the particle size (D90) at which the cumulative frequency from the small particle size side of the particle size distribution measured by the above-mentioned laser diffraction particle size distribution meter is 90%. This is the value divided by the particle size (D10) at which the cumulative frequency from the small particle size side is 10%.

The polyamide powder of the present invention preferably has a sphericity of 80 or more and 100 or less. When the sphericity is less than 80, fluidity deteriorates and the surface of the shaped object becomes rough. The sphericity is preferably 85 or more and 100 or less, more preferably 90 or more and 100 or less, even more preferably 93 or more and 100 or less, particularly preferably 95 or more and 100 or less, and extremely preferably 97 or more and 100 or less.

The sphericity of the polyamide powder of the present invention is determined by randomly observing 30 particles from a photograph taken with a scanning electron microscope and using the short axis and long axis according to the following formula.

Note that S: sphericity, a: major axis, b: minor axis, and n: number of measurements is 30.

The surface smoothness and internal solidity of the polyamide powder of the present invention can be expressed by the BET specific surface area determined by gas adsorption. If the surface of the polymer powder is smooth and the inside is solid, the surface area is small, the fluidity is improved, and the surface of the molded object is smooth, which is preferable. Here, it means that the smoother the surface, the smaller the BET specific surface area. Specifically, it is preferably 10 m ² /g or less, more preferably 5 m ² /g or less, even more preferably 3 m ² /g or less, particularly preferably 1 m ² /g or less, and most preferably 0.5 m ² /g or less. The lower limit is theoretically 0.05 m ² /g when the particle diameter is 100 μm.

The BET specific surface area is measured according to the Japanese Industrial Standards (JIS) JIS R 1626 (1996) "Method for measuring specific surface area by gas adsorption BET method".

The solidity of the polyamide powder of the present invention can also be evaluated by the following formula showing the ratio of the BET specific surface area to the theoretical surface area calculated from the D50 particle size. The closer the above ratio is to 1, the more adsorption occurs only on the outermost surface of the particle, indicating that the particle has a smoother surface and a solid particle. It is preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and most preferably 2 or less. Further, the lower limit value is theoretically 1.

Note that R: ratio of surface area, D: D50 particle diameter, α: density of polyamide, and A: BET specific surface area.

To produce the polyamide powder of the present invention, the polyamide monomer described in International Publication No. 2018/207728 previously disclosed by the present inventors is added to the polyamide in the presence of a polymer that is incompatible with the polyamide. A method can be used in which the polyamide powder is polymerized at a temperature higher than the crystallization temperature of the polyamide, and then the polyamide powder is washed and dried.

The polyamide powder preferably used in the present invention has a content of subcomponents used in the polyamide powder manufacturing process or the like of less than 0.1% by mass. Since such subcomponents cause a decrease in the fluidity and recyclability of the powder composition, their content is more preferably less than 0.05% by mass, even more preferably less than 0.01% by mass, and less than 0.007% by mass. is particularly preferred, less than 0.004% by weight is highly preferred, and less than 0.001% by weight is most preferred. The content of such subcomponents can be analyzed by a known method. For example, after extracting polyamide powder with water or an organic solvent, removing the solvent, and performing gel permeation chromatography using water as a solvent. Can be quantified.

The obtained polyamide powder may be subjected to additional heat treatment as long as the effect of the present invention is not impaired. A known method can be used for the heat treatment, and an appropriate method can be selected from normal pressure heat treatment using an oven, reduced pressure heat treatment using a vacuum dryer, and pressurized heat treatment in which the powder is heated together with water in a pressure vessel such as an autoclave. By carrying out the heat treatment, it is possible to control the molecular weight, crystallinity, and melting point of the polyamide to the desired range.

The powder composition of the present invention is characterized by containing an inorganic reinforcing material composed of an inorganic compound. The inorganic reinforcing material may be dry blended with the polyamide powder or may be contained inside the polyamide powder, but it is preferable to dry blend the inorganic reinforcing material in order to control the polyamide powder to a spherical shape and improve flowability.

Such inorganic reinforcing materials include, for example, glass-based fillers such as glass fiber, glass beads, glass flakes, and expanded glass beads; nepheline syenite fine powder, calcined clays such as montmorillonite and bentonite; clays (aluminum silicate powders) such as silane-modified clay; silicic acid-containing compounds such as talc, diatomaceous earth, and silica sand; crushed natural minerals such as pumice powder, pumice balloons, slate powder, and mica powder; minerals such as barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, and graphite; silicas (silicon dioxides) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide); and alumina colloids (alumina). Examples of such fillers include alumina such as Luminasol, alumina white, calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, and special calcium carbonate-based fillers, fly ash spheres, volcanic glass hollow bodies, synthetic inorganic hollow bodies, potassium titanate monocrystal, potassium titanate fiber, carbon fiber, carbon nanotubes, carbon hollow spheres, fullerenes, anthracite powder, cellulose nanofibers, artificial cryolite, titanium oxide, magnesium oxide, basic magnesium carbonate, dolomite, calcium sulfite, mica, asbestos, calcium silicate, molybdenum sulfide, boron fiber, and silicon carbide fiber. Glass-based fillers, minerals, and carbon fibers are preferred because they are hard and have a large effect of improving strength, and glass-based fillers are even more preferred because they have a narrow particle size distribution and fiber size distribution. These inorganic reinforcing materials can be used alone or in combination of two or more types.

Elements constituting such inorganic reinforcements generally include sodium, potassium, magnesium, calcium, barium, titanium, iron, aluminum, zinc, boron, aluminum, silicon, oxygen, etc., but they have high rigidity and heat resistance. It is preferable to contain silicon and aluminum, and it is more preferable to contain silicon, aluminum, magnesium, and calcium because they can contribute to improvement. Specific examples of inorganic reinforcing materials containing silicon and aluminum include mica, kaolin clay, montmorillonite, glass fillers, etc. Specific examples of inorganic reinforcing materials containing silicon, aluminum, magnesium, and calcium include Examples include glass fillers.

In the present invention, the constituent elements of the inorganic reinforcing material can be determined from the spectral data detected by an energy dispersive X-ray analyzer.

Examples of glass-based fillers preferably used in the present invention include glass fibers, glass beads, glass flakes, and foamed glass beads, but they are capable of producing high elastic modulus in three-dimensional objects. and glass fibers, glass beads, or mixtures thereof are more preferred. Among these, glass fibers or a mixture of glass fibers and glass beads are particularly preferred since they can suppress warpage of the shaped object. Furthermore, glass fiber is extremely preferable since the shaped article has high strength. Further, a mixture of glass fiber and glass beads is extremely preferable since the strength anisotropy of the shaped object is small. The glass fiber may have a circular cross section or a flat cross section.

To improve the adhesion between the inorganic reinforcing material and the polyamide powder, it is possible to use an inorganic reinforcing material that has been surface-treated, as long as the effect of the present invention is not impaired. Examples of such surface treatments include silane coupling agents such as aminosilane, epoxysilane, and acrylicsilane. These surface treatment agents may be fixed on the surface of the inorganic reinforcing material by a coupling reaction, or may cover the surface of the inorganic reinforcing material. However, in terms of recycling the powder used in three-dimensional modeling, those that are fixed by a coupling reaction are preferred because they are less likely to be modified by heat, etc.

The average major axis diameter of the inorganic reinforcing material of the present invention is in the range of 10 to 120 μm. If the average major axis diameter exceeds 120 μm, unevenness of the inorganic reinforcing material will appear from the modeling surface, impairing surface smoothness, which is not preferable. If the average major axis diameter is less than 10 μm, it is not preferable because it cannot contribute to improving the elastic modulus. The upper limit of the average major axis diameter of the inorganic reinforcing material is preferably 110 μm or less, more preferably 100 μm or less, even more preferably 95 μm or less, and particularly preferably 90 μm or less. The lower limit is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

The shape of the inorganic reinforcing material of the present invention is expressed by the ratio of the average major axis diameter to the average minor axis diameter, which is the average major axis diameter/average minor axis diameter, and is 2 or more and 12 or less. If the average major axis diameter/average minor axis diameter exceeds 12, the orientation in the X direction in the shaped article to be described later becomes significant, and the strength anisotropy with respect to the Z direction increases, which is not preferable. If the average major axis diameter/average minor axis diameter is less than 2, it is not preferable because it cannot contribute to improving the strength. The upper limit of the average major axis diameter/average minor axis diameter is preferably 11 or less, more preferably 10 or less, and even more preferably 9 or less. The lower limit is preferably 3 or more, more preferably 4 or more.

In addition, in the present invention, the average major axis diameter and average minor axis diameter of the inorganic reinforcing material are the major axis diameters of 100 fibers or particles randomly selected from a photograph obtained by imaging the inorganic reinforcing material with a scanning electron microscope. This is the number average value obtained by observing the minor axis diameter. The major axis diameter is the diameter at which the distance between two parallel lines is maximum when the particle image is sandwiched between two parallel lines, and the minor axis diameter is the diameter at which the distance between two parallel lines is the maximum in the direction perpendicular to the major axis diameter. This is the diameter that minimizes the distance between parallel lines when sandwiched between lines. When measuring the average major axis diameter and average minor axis diameter of an inorganic reinforcement, select an inorganic reinforcement material from a scanning electron micrograph of a powder composition as shown in Figure 2, and measure the major axis diameter and minor axis diameter. You can.

The blending amount X(B) of the inorganic reinforcing material is 5% by weight or more and 60% by weight or less based on the total weight of the powder composition. The upper limit of the blending amount is preferably 55% by weight or less, more preferably 50% by weight or less. Further, the lower limit of the blending amount is preferably 10% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more. If the blending amount of the inorganic reinforcing material is 5% by weight or more, the elastic modulus and strength of the molded product obtained by three-dimensionally molding the powder composition can be improved. Further, if the amount of the inorganic reinforcing material is 60% by weight or less, the fluidity of the powder composition is not deteriorated and a shaped article with excellent surface smoothness tends to be obtained.

The powder composition of the present invention preferably contains a flow aid in order to improve flowability. The flow aid refers to a substance that suppresses powder agglomeration due to the adhesive force between powders. By including such a flow aid, the flowability of the powder composition can be improved, that is, the angle of repose, which is an index of flowability described below, can be improved to a desired range, and defects that cause deterioration of mechanical properties can be reduced. This tends to further improve the appearance of the resulting model.

Such flow aids include, for example, silica (silicon dioxide) such as fused silica, crystalline silica, and amorphous silica, alumina (aluminum oxide), alumina colloid (alumina sol), alumina such as alumina white, light calcium carbonate, and heavy calcium carbonate. , pulverized calcium carbonate, calcium carbonate such as special calcium carbonate fillers, titanium oxide, magnesium oxide, basic magnesium carbonate, potassium titanate fiber, boron fiber, silicon carbide fiber, etc. More preferred are silica, alumina, calcium carbonate powder, and titanium oxide. Particularly preferred is silica, since it is hard and can contribute to improving strength and fluidity.

Commercial products of such silica include fumed silica "AEROSIL" (registered trademark) series manufactured by Nippon Aerosil Co., Ltd., dry silica "Rheolo Seal" (registered trademark) series manufactured by Tokuyama Co., Ltd., and sol-gel silica powder X manufactured by Shin-Etsu Chemical Co., Ltd. -24 series etc.

The flow aid preferably has a D50 particle diameter of 100 nm or more and 300 nm or less. The upper limit of the D50 particle size of the flow aid is more preferably 270 nm, even more preferably 250 nm, particularly preferably 230 nm, and extremely preferably 200 nm. The lower limit is more preferably 110 nm, further preferably 120 nm, particularly preferably 130 nm, and extremely preferably 140 nm. When the D50 particle size of the flow aid is within the above range, the flowability of the powder composition is improved and the flow aid tends to be able to be uniformly dispersed in the powder composition.

The D50 particle size of the flow aid in the present invention is defined as the cumulative curve obtained by analyzing the scattered laser light by dynamic light scattering, taking the total volume of fine particles as 100%, and calculating the cumulative curve from the small particle size side. is the particle diameter (D50) at which 50%.

The blending amount of the flow aid is preferably 0.01% by weight or more and 2.0% by weight or less based on the total weight of the powder composition. The upper limit of the blending amount is more preferably 1.5% by weight or less, further preferably 1.0% by weight or less, particularly preferably 0.8% by weight or less, and extremely preferably 0.7% by weight or less. Further, the lower limit of the blending amount is more preferably 0.02% by weight or more, further preferably 0.03% by weight or more, and particularly preferably 0.04% by weight or more. If the blending amount of the flow aid is 0.01% by weight or more, the fluidity of the powder composition will further improve, and the filling properties when molded will increase, so voids that will cause defects in mechanical properties will be less likely to occur. , the resulting shaped objects tend to exhibit high strength. Furthermore, if the blending amount of the flow aid is 2.0% by weight or less, sintering will not be hindered due to the flow aid coating the surface of the polyamide powder, and a molded object with high strength will tend to be obtained. It is in.

The powder composition of the present invention is preferably a powder mixture obtained by dry blending the above-mentioned polyamide powder with an inorganic reinforcing material and, if necessary, a flow aid and other additives. It may be something like that. If more than necessary shearing force is applied during blending, the inorganic reinforcing material may be damaged, so it is preferable to select a mixing method that does not apply more than necessary shearing force. Alternatively, a powder composition containing the inorganic reinforcing material may be prepared by powdering a polyamide resin into which the inorganic reinforcing material has been kneaded.

One of the advantages of the powder composition of the present invention is that the powder composition exhibits high fluidity. Any known measuring method can be used as the index. A specific example is the angle of repose, which is preferably 60 degrees or less. The temperature is more preferably 50 degrees or less, further preferably 40 degrees or less, particularly preferably 35 degrees or less. The lower limit is usually 30 degrees or more. Due to its high fluidity, the powder composition of the present invention is suitable for manufacturing three-dimensional objects using a powder bed fusion bonding method.

The filling properties of the powder composition of the present invention are determined by the rough filling rate: true density T (A) of the polyamide powder (A), true density T (B) of the inorganic reinforcing material (B), and bulk density D of the powder composition. Then, it can be expressed as D/{T(A)×(100−X(B))/100+T(B)×X(B)/100}. The rough filling rate of the powder composition of the present invention is 0.40 or more and 0.70 or less. If the rough filling rate is less than 0.40, the voids between the powders will be large, and when applied to three-dimensional modeling, melting and sintering will not progress sufficiently, causing voids to occur in the modeled object, and This is not preferable because it is difficult to obtain. If the rough filling ratio exceeds 0.70, the powder becomes excessively densely packed and is restrained, impairing fluidity, which is not preferable. The lower limit of the rough filling rate is preferably 0.41 or more, more preferably 0.42 or more, and even more preferably 0.43 or more. Moreover, the upper limit is preferably 0.65 or less, more preferably 0.62 or less, and even more preferably 0.60 or less.

In the present invention, the bulk density of the powder composition refers to the mass per unit volume when the powder is filled into a container. Here, the bulk density is measured for a powder composition according to the Japanese Industrial Standards (JIS) JIS K 7365 (1999) "How to determine the apparent density of a material that can be poured from a defined funnel."

In the present invention, the true density T(A) of the polyamide powder (A) and the true density T(B) of the inorganic reinforcing material (B) can be based on literature values, for example, polyamide 6 is 1.1 g/cm. ³ , numerical values such as 1.0 g/cm ³ for polyamide 12, 1.1 g/cm ³ for polyamide 1010, 2.6 g/cm ³ for glass fiber, and 2.5 g/cm ³ for glass beads can be used.

Methods for increasing the rough filling rate include using an inorganic reinforcing material with excellent filling properties and short fiber length, using a flow aid with a particle size of 100 nm to 300 nm that has an appropriate dispersion force, and using a true spherical material. This can be achieved by a method using polyamide powder with a high polyamide content of 80 or more, a method using a polyamide powder with a high melting point with many amide bonds, or a combination thereof.

In addition, in the powder bed fusion bonding method, a shaped object is produced using a portion of the powder composition used, and a large amount of the powder composition remains. Reusing the powder composition becomes important from a cost perspective. To this end, it is important not to change the properties of the powder composition during the heating and shaping process. Examples of such methods include, for example, adding a stabilizer such as an antioxidant to the inside of the particles to suppress thermal deterioration, and reducing the terminal groups of polyamide to suppress changes in molecular weight during modeling. can be mentioned. It is also preferable to use an inorganic reinforcing material that is not denatured by heat as the inorganic reinforcing material to be blended into the powder composition. By appropriately using such adjustments, it tends to be possible to achieve both formability and reuse.

The powder composition of the present invention is a useful material for producing three-dimensional objects using a powder bed fusion bonding method. Hereinafter, a method for manufacturing a three-dimensional structure will be described using FIG. 1.

In step (a), the stage 2 of the tank 1 in which the modeled object is formed is lowered.

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

In step (c), the powder composition P filled in the tank 1 to a predetermined stack height in step (b) is given thermal energy 6 capable of melting, and selectively melted and sintered in accordance with the modeling data.

In the powder bed fusion bonding method, the three-dimensional structure 10 is obtained by repeatedly performing the steps (a) to (c) above.

Examples of the method of selectively melting and sintering in step (c) include selective laser sintering, in which the powder composition is bonded by irradiating a laser to a shape corresponding to the cross-sectional shape of the modeled object. It will be done. In addition, there is a printing process in which an energy absorption promoter or energy absorption inhibitor is printed in a shape that corresponds to the cross-sectional shape of the object to be modeled, and a selective absorption (or suppression) sintering method in which resin powder is bonded using electromagnetic radiation. can also be mentioned.

The laser beam used in the selective laser sintering method is not particularly limited as long as it does not impair the quality of the powder composition or the shaped object. Examples include carbon dioxide laser, YAG laser, excimer laser, He--Cd laser, and semiconductor-excited solid-state laser. Among these, carbon dioxide laser is preferred because it is easy to operate and control.

The electromagnetic radiation used in selective absorption (inhibited) sintering may be any type that does not impair the quality of the powder composition or the molded object, but infrared radiation is preferred because it is relatively inexpensive and provides energy suitable for molding. The electromagnetic radiation may or may not be coherent.

Energy absorption enhancers are substances that absorb electromagnetic radiation. Such substances include carbon black, carbon fiber, copper hydroxyphosphate, near-infrared absorbing dye, near-infrared absorbing pigment, metal nanoparticles, polythiophene, poly(p-phenylene sulfide), polyaniline, poly(pyrrole), Consisting of polyacetylene, poly(p-phenylene vinylene), polyparaphenylene, poly(styrene sulfonate), poly(3,4-ethylenedioxythiophene)-poly(styrene phosphonate) p-diethylaminobenzaldehyde diphenylhydrazone, or a combination thereof Examples include conjugated polymers, which may be used alone or in combination.

Energy absorption inhibitors are substances that have low absorption of electromagnetic radiation. Examples of such materials include materials that reflect electromagnetic radiation such as titanium, heat-insulating powders such as mica powder and ceramic powder, and water, and these may be used alone or in combination.

These selective absorbents or selective inhibitors may be used alone or in combination.

In the step of printing the selective absorbent or selective inhibitor into a shape corresponding to the cross-sectional shape of the object to be formed, a known method such as inkjet printing can be used. In this case, the selective absorbent and selective inhibitor may be used as they are, or may be used after being dispersed or dissolved in a solvent.

The three-dimensional structure of the present invention can be obtained by modeling the powder composition of the present invention using a powder bed fusion bonding method. Hereinafter, the three-dimensional structure of the present invention will be explained.

The surface roughness of the three-dimensional structure of the present invention is 20 μm or less. The smaller the surface roughness, the better the adhesion of the joints between the objects, so the surface roughness of the objects is preferably 18 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, and particularly preferably 10 μm or less. Further, the lower limit is not particularly limited, and a smaller one is preferable, but the lower limit is usually 1 μm.

The surface roughness of the model is determined by observing the surface of the model using an optical microscope, converting the unevenness of the model's surface into a three-dimensional image using automatic synthesis mode, and then obtaining a cross-sectional height profile over a length of 1 mm or more. The surface roughness Ra is calculated using the arithmetic mean.

The X-direction elastic modulus of the three-dimensional object of the present invention is 3500 MPa or more. The higher the elastic modulus, the more rigid the object is and the less likely it is to deform. Therefore, the X-direction elastic modulus of the object is preferably 3800 MPa or more, more preferably 4000 MPa or more, even more preferably 4500 MPa or more, and particularly preferably 5000 MPa or more. There is no particular upper limit, but generally, if the elastic modulus becomes too large, it tends to become brittle and have low strength, so it is preferably 20000 MPa or less, more preferably 15000 MPa or less, even more preferably 12000 MPa or less, and particularly preferably 10000 MPa or less.

In addition, in the present invention, the X-direction elastic modulus is determined based on the Japanese Industrial Standard (JIS standard) JIS K7171 (2016) "Plastics - How to determine bending properties" for a bending test piece manufactured with the aforementioned X direction facing the longest side in three-dimensional modeling. This is the flexural modulus measured according to ``.

The X-direction bending strength of the three-dimensional object of the present invention is preferably 65 MPa or more. The greater the X-direction bending strength, the more the object can withstand the force from the direction in which the greatest stress is applied, so the X-direction bending strength of the object is more preferably 70 MPa or more, even more preferably 80 MPa or more, particularly preferably 90 MPa or more, extremely preferably 100 MPa or more, and most preferably 105 MPa or more.

Further, the strength anisotropy of the three-dimensional structure of the present invention can be evaluated by Z-direction bending strength/X-direction bending strength. The larger the Z-direction bending strength/X-direction bending strength, the less strength anisotropy and the better handling properties, so it is preferably 0.4 or more, more preferably 0.5 or more, and even more preferably 0.6 or more. , particularly preferably 0.7 or more.

In addition, in the present invention, the X-direction bending strength and the Z-direction bending strength are determined in accordance with the Japanese Industrial Standard (JIS standard) JIS K7171 (2016) "Plastic - How to determine bending properties", with the above-mentioned X direction facing the longest side. These are the values of the maximum bending stress measured for a shaped bending test piece and a bending test piece shaped with the longest side in the Z direction.

It is preferable that the deflection temperature under load of the three-dimensional structure of the present invention is 150° C. or higher. The higher the deflection temperature under load, the less likely the shaped article is to deform in a high-temperature environment, so the deflection temperature under load of the shaped article is more preferably 170°C or higher, even more preferably 185°C or higher, and particularly preferably 200°C or higher.

In the present invention, the deflection temperature under load is a value measured at a load of 0.45 MPa in accordance with the Japanese Industrial Standard (JIS standard) JIS K7191-1 (2015) "Plastics - How to determine deflection temperature under load."

In addition, in three-dimensional modeling, a shaped object is formed by melting and sintering a powder-filled state under normal pressure, which usually involves changes in density due to shrinkage. Therefore, in order to obtain the dimensions of the three-dimensional structure with high accuracy based on desired modeling data, it is preferable to have an appropriate amount of holes inside. The proportion and shape of the pores present in the three-dimensional structure of the present invention can be observed by X-ray CT.

When the three-dimensional structure of the present invention is imaged by X-ray CT, the ratio of the portion observed as a void to the volume of the entire structure can be expressed as a porosity. The porosity observed by X-ray CT measurement of the three-dimensional structure of the present invention is preferably 0.1 volume % or more and 10 volume % or less. The lower limit of the porosity is more preferably 0.2 volume % or more, even more preferably 0.3 volume % or more, and 0.5 volume % or more, because if it is too small, the problem that the entire model shrinks with respect to the modeling data will occur. Particularly preferred is volume % or more. Moreover, the upper limit thereof is more preferably 5.0 volume % or less, further preferably 4.0 volume % or less, and particularly preferably 3.0 volume % or less, since a large number of pores causes a decrease in strength.

The size of each independent hole observed as a void when the three-dimensional object of the present invention is imaged by X-ray CT can be expressed as a sphere-equivalent diameter. The three-dimensional object of the present invention is characterized in that the average sphere-equivalent diameter of the voids observed by X-ray CT measurement is 1 μm or more and 100 μm or less. In the case of melt molding that does not involve a three-dimensional molding process, the average sphere-equivalent diameter of the voids is usually designed to be less than 1 μm, and in the case of intentionally forming voids such as foam molding, the average sphere-equivalent diameter of the voids is usually more than 100 μm, so that the average sphere-equivalent diameter is 1 μm or more and 100 μm or less, which is a characteristic of the three-dimensional object. As described above, in three-dimensional molding under normal pressure, a certain amount of voids are generated, so the lower limit is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The upper limit is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less, because large voids become defects and cause a decrease in the strength of the molded object.

Furthermore, compared to normal melt molding, three-dimensional objects are obtained by crystallization under normal pressure and through a process of lowering the temperature at a slower rate, so the state of the crystals is different from that of normal melt molding. However, since it is difficult to express this as a characteristic of a product, it is limited by the manufacturing method, which is obtained by three-dimensional modeling, preferably by a powder bed fusion bonding method. It is known that with normal melt molding, molded products with smooth surfaces and high elastic modulus can be obtained depending on the structure of the mold, but three-dimensional molding that allows molding of complex shapes is possible. In modeling, it has not been possible to obtain a molded product with a smooth surface and a high modulus of elasticity, and this was made possible for the first time by the present invention.

The three-dimensional object of the present invention combines surface smoothness with a high modulus of elasticity, has excellent adhesion at the joints between objects, and exhibits good airtightness. The three-dimensional object obtained using the powder composition of the present invention can be effectively used for automobile parts that require high heat resistance and modulus of elasticity, particularly automobile engine peripheral parts, automobile underhood parts, automobile gear parts, automobile interior parts, automobile exterior parts, intake and exhaust system parts, engine cooling water system parts, and automobile electrical parts, and it is possible to obtain three-dimensional objects of complex shapes that have been optimally designed.

The present invention will be explained below based on examples.
(1) D50 particle size of polyamide powder A dispersion liquid in which approximately 100 mg of polyamide powder was predispersed in approximately 5 mL of deionized water was measured using a laser diffraction particle size distribution analyzer (Microtrac MT3300EXII) manufactured by Nikkiso Co., Ltd. After adding it to a possible concentration and performing ultrasonic dispersion for 60 seconds at 30W in the measuring device, the cumulative frequency from the small particle size side of the particle size distribution measured in a measurement time of 10 seconds is 50%. The particle size was defined as the D50 particle size. Note that the refractive index at the time of measurement was 1.52, and the refractive index of the medium (deionized water) was 1.333.

(2) Sphericity of polyamide powder The sphericity of polyamide powder is determined by observing 30 particles at random from a photograph taken with a scanning electron microscope (JSM-6301NF manufactured by JEOL Ltd.), and determining their short axis and long axis. It was calculated according to the following formula.

Note that S: sphericity, a: major axis, b: minor axis, and n: number of measurements is 30.

(3) BET specific surface area According to the Japanese Industrial Standards (JIS) JISR1626 (1996) "Method for measuring specific surface area by gas adsorption BET method", approximately 0.2 g of polyamide powder was placed in a glass cell using BELSORP-max manufactured by Nippon Bell. After degassing under reduced pressure at 80° C. for about 5 hours, the krypton gas adsorption isotherm at liquid nitrogen temperature was measured and calculated by the BET method.

(4) Average major axis diameter and average minor axis diameter of inorganic reinforcement The inorganic reinforcement was observed with a scanning electron microscope (JSM-6301NF) manufactured by JEOL Ltd., and 100 inorganic reinforcements were randomly selected from the photograph. The average value of the major axis and minor axis of the reinforcement was defined as the average major axis diameter and the average minor axis diameter.

(5) Constituent elements of inorganic reinforcement The inorganic reinforcement was accelerated using a scanning electron microscope (Regulus 8220) manufactured by Hitachi High-Technologies Corporation and an energy dispersive X-ray analyzer (“XFlash” (registered trademark) 5060FlatQUAD) manufactured by BRUKER. Images were taken under conditions of a voltage of 5 kV and a measurement time of 180 seconds. From the obtained spectrum data, the peak at 1.49 keV is assigned to the aluminum element, and the peak at 1.74 keV is assigned to the silicon element, and if a peak of 1 cps/eV or more is detected, it is determined that the element contains the element. I judged it.

(6) D50 particle size of flow aid A sample in which flow aid was dispersed in deionized water or ethanol at a concentration of 0.1% by weight was measured using a zeta potential/particle size measuring device (ELSZ-) manufactured by Otsuka Electronics Co., Ltd. Measured by the dynamic light scattering method described in 2), the particle size at which the cumulative frequency from the small particle size side of the particle size distribution is 50% was defined as the D50 particle size.

(7) Bulk density and crude packing ratio of powder composition The bulk density of the powder composition was determined according to Japanese Industrial Standards (JIS) JIS Z 7365 (1999) by dropping 50 g of polymer powder from a funnel into a 100 ^cm3 measuring cylinder, reading the volume, and dividing the weight of the powder composition by the volume. The crude packing ratio D/{T(A)×(100−X(B))/100+T(B)×X(B)/100} was calculated, where T(A) is the true density of polyamide powder (A), T(B) is the true density of inorganic reinforcing material (B), and D is the bulk density of the powder composition. The true densities used were 1.1 g/cm ³ for polyamide 6, 1.0 g/cm ³ for polyamide 12, 1.1 g/cm ³ for polyamide 1010, 1.0 g/cm ³ for polyamide 11, 2.6 g/cm ³ for glass fiber, 2.5 g/cm ³ for glass beads, and 1.8 g/cm ³ for carbon fiber.

(8) Judging the external appearance of the three-dimensional object The resulting three-dimensional object has no defects or spots of 1 mm or more with a rating of ``◎'', and those with no defects of 1 mm or more but with some spots are marked with an ``〇''. ”, and those with defects of 1 mm or more were rated “△”.

(9) Judgment of warpage of the model Place the obtained test piece on a horizontal surface with an upward convex position, insert a precision taper gauge into the gap between the horizontal surface and the test piece, and measure the height of the gap. Then, the value converted per 10 cm of test piece length was calculated as the amount of warpage, and the amount of warpage was evaluated based on the following criteria.
○: The amount of warpage is 0.1 mm/10 cm or less.
Δ: The amount of warpage is greater than 0.1 mm/10 cm and less than 0.3 mm/10 cm.
×: The amount of warpage is greater than 0.3 mm/10 cm.
Ranks “〇” and “△” were considered to be passed.

(10) Surface roughness of the modeled object The surface of the modeled object was observed at a magnification of 200 times using an optical microscope (VHX-5000) manufactured by Keyence Corporation and a VH-ZST (ZS-20) objective lens. After creating a three-dimensional image of the unevenness on the surface of the model in automatic synthesis mode using the software (system version 1.04) included with the device, the height profile of the cross section over a length of 1 mm or more is obtained, and the surface roughness is determined by arithmetic averaging. The degree Ra was calculated. It shows that the smaller the surface roughness Ra is, the more excellent the surface smoothness is.

(11) Measurement of bending elastic modulus and bending strength of the three-dimensional model The bending elastic modulus and bending strength of the three-dimensional model were measured using a powder bed fusion method 3D printer (RaFaElII 150C-HT) manufactured by Aspect Co., Ltd. with a width of 10 mm. A test piece with a length of 80 mm and a thickness of 4 mm was prepared so that the length direction of the 80 mm was in the X direction or the Z direction. The bending elastic modulus and bending strength in the X direction and the Z direction were measured using the same. In accordance with JIS K7171 (2016), a three-point bending test was performed under the conditions of a distance between fulcrums of 64 mm and a test speed of 2 mm/min to determine the bending elastic modulus. The bending strength was defined as the maximum bending stress. The measurement temperature was room temperature (23° C.), the number of measurements was n=5, and the average value was determined.

(12) Deflection temperature under load of a three-dimensional object The deflection temperature under load of a three-dimensional object was measured using a powder bed fusion method 3D printer (RaFaElII 150C-HT) manufactured by Aspect Co., Ltd. A test piece was prepared so that the length direction of 80 mm was in the X direction, and a load of 0.45 MPa was applied using a heat distortion tester (No. 148) manufactured by Yasuda Seiki Seisakusho Co., Ltd. according to JIS K7191-1 (2015). Measured at The number of measurements was n=3, and the average value was calculated.

(13) Average spherical equivalent diameter of holes in the modeled object Three-dimensional transmission image observation was performed using an X-ray CT device (Xradia 510 Versa) manufactured by ZEISS with a resolution of 5 μm, a field of view of 5 mm, a voltage of 80 kV, and a power of 7 W. Ta. The pores in the observed image were subjected to labeling processing, and the equivalent sphere diameter, which is the diameter of each independent pore when it was made into a sphere, was calculated, and the average value thereof was determined.

(14) MIX ratio of recycled modeling The used powder remaining in the modeling chamber after modeling using Aspect Co., Ltd.'s powder bed fusion method 3D printer (RaFaElII 150C-HT) is collected, and a certain ratio of unused powder is collected. After mixing with the powder used, three-dimensional modeling was performed again. When the surface roughness, flexural modulus, and flexural strength of the model obtained here show a change of 10% or less compared to the case where the model was modeled only with unused powder, the recycled model was evaluated as "〇". . The mixing ratio of the used powder when the recycled model was rated as "○" was defined as the MIX ratio.

[Manufacture example 1]
In an autoclave equipped with a 3L helical ribbon type stirring blade, 300 g of ε-caprolactam (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added as a monomer for polyamide, and polyethylene glycol (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added as a polymer incompatible with polyamide. 700 g of primary polyethylene glycol 20,000 (weight average molecular weight 18,600) manufactured by Hikari Pure Chemical Industries, Ltd. and 1000 g of water were added to form a homogeneous solution, which was then sealed and replaced with nitrogen. Thereafter, the stirring speed was set to 40 rpm and the temperature was raised to 210°C. At this time, after the system pressure reached 10 kg/cm ² , water vapor was controlled while being slightly released so as to maintain the pressure at 10 kg/cm ² . After the temperature reached 210° C., the pressure was released at a rate of 0.2 kg/cm ² ·min. Thereafter, the temperature was maintained for 1 hour while flowing nitrogen to complete polymerization, and a slurry was obtained from the mixture of polyamide powder and polyethylene glycol by discharging it into a 2000 g water bath while the polyethylene glycol remained in a molten state. After the slurry was sufficiently homogenized by stirring, it was filtered, 2000 g of water was added to the filtered product, and it was washed at 80°C. Thereafter, the slurry liquid from which aggregates were removed through a 100 μm sieve was filtered again, and the isolated filtered product was dried at 80° C. for 12 hours to produce 170 g of polyamide 6 powder. The obtained polyamide powder had a D50 particle diameter of 51 μm, a D90/D10 of 2.5, a sphericity of 95, a BET specific surface area of 0.16 m ² /g, and R=1.3.

[Manufacture example 2]
Polyamide 12 powder was produced in the same manner as in Production Example 1, except that ε-caprolactam was used as the polyamide monomer, aminododecanoic acid (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was used, and the polymerization temperature was changed to 210°C. The obtained polyamide powder had a D50 particle size of 55 μm and a sphericity of 97.

[Production Example 3]
Polyamide 1010 powder was produced in the same manner as in Production Example 1, except that ε-caprolactam was replaced with 216 g of sebacic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 184 g of diaminodecane (manufactured by Tokyo Chemical Industry Co., Ltd.) as the polyamide monomer, and the polymerization temperature was changed to 210° C. The D50 particle size of the obtained polyamide powder was 49 μm and the sphericity was 93.

[Manufacture example 4]
Polyamide 11 powder was produced in the same manner as in Production Example 1, except that ε-caprolactam was used as the polyamide monomer, aminoundecanoic acid (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was used, and the polymerization temperature was changed to 210°C. The obtained polyamide powder had a D50 particle size of 51 μm and a sphericity of 92.

[Manufacture example 5]
Same as Production Example 1 except that the polyamide monomers were 600 g of ω-laurinlactam (manufactured by Tokyo Kasei Kogyo Co., Ltd.) instead of ε-caprolactam, 400 g of polyethylene glycol, and 80 g of water, and the initial heating temperature was changed to 280°C. Polyamide 12 powder was produced by the method described above. The obtained polyamide powder had a D50 particle size of 53 μm and a sphericity of 91.

[Example 1]
1050 g of the polyamide 6 powder of Production Example 1 was used as the polyamide powder (A), and 450 g of glass fiber EPG40M-10A (manufactured by Nippon Electric Glass Co., Ltd., average major axis diameter 43 μm, average short axis diameter 10 μm) was used as the inorganic reinforcement (B). Mixed. Furthermore, 4.5 g of trimethylsilylated amorphous silica X-24-9500 (manufactured by Shin-Etsu Chemical Co., Ltd., D50 particle size 170 nm) was added as a flow aid (C) to form a powder composition. Using 1.5 kg of this powder composition, a three-dimensional object was manufactured using a powder bed fusion bonding device (RaFaElII 150C-HT) manufactured by Aspect Co., Ltd. The setting conditions were as follows: a 60 WCO ₂ laser was used, the stacking height was 0.1 mm, the laser scanning interval was 0.1 mm, the laser scanning speed was 5 m/s, and the laser output was 12 W. The temperature was set such that the component bed temperature was -15°C below the melting point, and the supply tank temperature was set at -5°C, the crystallization temperature. The appearance of the obtained three-dimensional structure was good, with a surface roughness of 9 μm, an elastic modulus in the X direction of 5600 MPa, a bending strength in the X direction of 151 MPa, a bending strength in the Z direction of 115 MPa, a deflection temperature under load of 217°C, and no holes in X-ray CT. The ratio was 1.2% by volume, and the equivalent sphere diameter of the pores was 34 μm. Furthermore, when the used powder was collected and mixed with unused powder and the MIX ratio of recycled modeling was evaluated, the MIX ratio was 70%. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 2]
A three-dimensional model was produced in the same manner as in Example 1, except that 750 g of the polyamide 12 powder of Production Example 2 was used as the polyamide powder (A), and 750 g of glass fiber EPG40M-10A was used as the inorganic reinforcement (B). and recycling characteristics were evaluated (a scanning electron micrograph of the obtained powder composition is shown in FIG. 2). Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 3]
1200 g of polyamide powder (A), 300 g of glass fiber EPG 70M-01N (manufactured by Nippon Electric Glass Co., Ltd., average major axis diameter 73 μm, average minor axis diameter 10 μm) as an inorganic reinforcement (B), flow aid (C). A three-dimensional structure was produced in the same manner as in Example 1, except that the blending composition was changed to 3.0 g, and the recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 4]
A three-dimensional object was produced and its recyclability was evaluated in the same manner as in Example 1, except that the blending composition was changed to 900 g of polyamide powder (A), 600 g of glass fiber EPH80M-10A (manufactured by Nippon Electric Glass Co., Ltd., average major axis diameter 88 μm, average minor axis diameter 11 μm) as inorganic reinforcing material (B), and 7.5 g of flow aid (C). The powders used, the properties of the obtained object, and the MIX ratio, which is the recyclability, are shown in Table 1.

[Example 5]
A three-dimensional object was produced and its recyclability was evaluated in the same manner as in Example 1, except that the blending composition was changed to 900 g of polyamide powder (A), 120 g of glass fiber EPG40M-10A and 480 g of glass beads GB731A (manufactured by Potters Ballotini, average major axis diameter 27 μm, average minor axis diameter 26 μm) as inorganic reinforcing material (B), and 1.5 g of flow aid (C). The powders used, the properties of the obtained objects, and the MIX ratio, which is the recyclability, are shown in Table 1.

[Example 6]
A three-dimensional object was produced and its recyclability was evaluated in the same manner as in Example 1, except that the blending composition was changed to 1,125 g of polyamide powder (A) and 375 g of carbon fiber Panex 35 (manufactured by Zoltek, average major axis diameter 80 μm, average minor axis diameter 7 μm) as inorganic reinforcing material (B). The powders used, the properties of the obtained objects, and the MIX ratio, which is the recyclability, are shown in Table 1.

[Example 7]
The composition was changed to 1050 g of polyamide powder (A), 450 g of glass fiber EPG70M-01N as the inorganic reinforcement (B), and 4.5 g of fumed silica "AEROSIL (registered trademark)" R972 as the flow aid (C). A three-dimensional structure was produced in the same manner as in Example 1, except that the recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 8]
Polyamide "Amilan (registered trademark)" CM1007 manufactured by Toray Industries, Inc. was pulverized for 120 minutes using a jet mill (100AFG manufactured by Hosokawa Micron) to obtain a pulverized polyamide 6 powder having a D50 particle size of 50 μm and a sphericity of 60. A three-dimensional model was produced and recycled in the same manner as in Example 3, except that the pulverized polyamide 6 powder was used as the polyamide powder (A) and the amount of flow aid (C) was changed to 4.5 g. Characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 9]
A three-dimensional model was produced in the same manner as in Example 1, except that 1050 g of the polyamide 1010 powder of Production Example 3 was used as the polyamide powder (A), and 450 g of glass fiber EPG70M-01N was used as the inorganic reinforcement (B). and the recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 10]
A three-dimensional structure was produced in the same manner as in Example 9, except that the polyamide 11 powder of Production Example 4 was used as the polyamide powder (A), and the recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Example 11]
A three-dimensional structure was produced in the same manner as in Example 9, except that the polyamide 12 powder of Production Example 5 was used as the polyamide powder (A), and the recycling characteristics were evaluated. Table 1 shows the characteristics of the obtained model and the MIX ratio, which is the recycling characteristic.

[Comparative example 1]
900 g of the polyamide 1010 powder of Production Example 3 was used as the polyamide powder (A), 600 g of glass beads GB731 (manufactured by Potter's Barotini, average major axis diameter 31 μm, average minor axis diameter 31 μm) was used as the inorganic reinforcement (B), and the fluidized A three-dimensional structure was produced in the same manner as in Example 1, except that the amount of the auxiliary agent (C) was changed to 1.5 g, and the recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Comparative example 2]
Same as Example 1 except that 1500 g of polyamide 1010 powder of Production Example 3 was used as polyamide powder (A), no inorganic reinforcement (B) was added, and the amount of flow aid (C) was changed to 1.5 g. A three-dimensional model was created using the method described above, and its recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Comparative example 3]
A three-dimensional model was produced in the same manner as in Example 7, except that the blending composition was changed to 4.5 g of fumed silica "AEROSIL (registered trademark)" R972 as the flow aid (C), and the recycling characteristics were evaluated. did. The powder composition used had poor fluidity, and sintering was inhibited during shaping, making it impossible to obtain a shaped article.

[Comparative example 4]
A three-dimensional structure was produced in the same manner as in Example 3, except that the blending composition was changed to 1450 g of polyamide powder (A), 45 g of inorganic reinforcement (B), and 1.5 g of flow aid (C). were fabricated and their recycling characteristics were evaluated. Table 1 shows the powder used, the characteristics of the molded article obtained, and the MIX ratio, which is the recycling characteristic.

[Comparative example 5]
As the inorganic reinforcement (B), chopped glass fiber strands T-275H (manufactured by Nippon Electric Glass Co., Ltd., average major axis diameter 3000 μm, average minor axis diameter 10 μm) were crushed with a pestle in a mortar to give an average major axis diameter of 420 μm. A three-dimensional structure was produced in the same manner as in Example 6, except that a three-dimensional structure was used. When this powder was repeatedly recycled, the glass fibers agglomerated and did not flow, making it unusable for modeling. Table 1 shows the powder used and the characteristics of the molded article obtained.

In addition, in the types of reinforcing materials in Table 1, GF indicates glass fiber and GB indicates glass beads.

The modeled object obtained using the powder composition of the present invention has a high elastic modulus, and the powder used for modeling can also be recycled at a high rate, making it effective as a powder raw material for three-dimensional structures for industrial purposes. It can be used for. In a further preferred embodiment, it is also possible to obtain a shaped article with excellent surface smoothness. In particular, since it has a high elastic modulus of 3500 MPa or more, it can also be used as a structural member.

1 Tank for forming a model 2 Stage 3 for a tank for forming a model Supply tank 4 for pre-filling with the powder composition to be supplied Stage 5 for a tank for pre-filling the powder composition for supply Recoater 6 Thermal energy 7 , Y, Z coordinate system 8 Surface direction in which the powder compositions are stacked 9 Height direction in which the powder compositions are stacked 10 Three-dimensional structure P Powder composition

Claims (11)

A powder composition comprising a polyamide powder (A) , an inorganic reinforcing material (B) , and a flow aid (C) having a D50 particle size of 100 nm or more and 300 nm or less , the polyamide powder (A) having a D50 particle size of 100 nm or more and 300 nm or less. 1 μm or more and 100 μm or less, the average major axis diameter of the inorganic reinforcing material (B) is 10 μm or more and 120 μm or less, and the average major axis diameter/average minor axis diameter is 2 or more and 12 or less, based on the total weight of the powder composition. The content X (B) of the inorganic reinforcing material (B) is 5% by weight or more and 60% by weight or less, the true density T (A) of the polyamide powder (A), the true density T ( B), when the bulk density of the powder composition is D, the rough filling rate D/{T(A)×(100−X(B))/100+T(B)×X(B)/100} is 0.40 A powder composition characterized in that it is 0.70 or less. The powder composition according to claim 1, wherein the flow aid (C) is contained in an amount of 0.01% by weight or more and 2.0% by weight or less based on the total weight of the powder composition. 2. The powder composition of claim 1 , wherein the flow aid (C) is silica. The powder composition according to claim 1, wherein the inorganic reinforcing material (B) has an average major axis diameter of 30 μm or more and 90 μm or less. The powder composition according to claim 1, wherein the inorganic reinforcement (B) is glass fiber and/or carbon fiber. The powder composition according to claim 1, wherein the polyamide powder (A) has a sphericity of 80 or more and 100 or less. When a test piece with a width of 10 mm, a length of 80 mm, and a thickness of 4 mm was prepared using the powder bed fusion bonding method so that the length direction of the 80 mm was parallel to the movement of the recoater (X direction), The powder composition according to claim 1, wherein the test piece has a bending modulus of elasticity in the X direction of 3500 MPa or more as measured according to JIS K7171 (2016) . The powder composition according to claim 1, wherein the powder composition has a deflection temperature under load of 150° C. or higher measured at a load of 0.45 MPa when a three-dimensional structure is manufactured by a powder bed fusion bonding method. A method for manufacturing a three-dimensional object by a powder bed fusion bonding method using the powder composition according to any one of claims 1 to 8 . A powder composition comprising a polyamide powder (A), an inorganic reinforcing material (B) having an average major axis diameter of 10 μm or more and 120 μm or less, and a flow aid (C) having a D50 particle size of 100 nm or more and 300 nm or less, JIS K7171( A three-dimensional object obtained by a powder bed fusion bonding method using a powder composition having a bending modulus of elasticity in the A three-dimensional structure in which the average spherical equivalent diameter of pores observed by measurement is 1 μm or more and 100 μm or less. The three-dimensional structure according to claim 10 , wherein the number of pores observed by X-ray CT measurement is 0.1% by volume or more and 10% by volume or less.

Images