Method and apparatus for measuring the degree of deterioration of molding powder, method and apparatus for manufacturing recycled molding powder, and method and apparatus for manufacturing three-dimensional molded objects.

Abstract

Provided are: a method and a device for determining the degree of deterioration of a shaping powder which enable shaped objects to be inhibited from decreasing in mechanical property or dimensional accuracy; a method and a device for producing a reclaimed shaping powder; and a method and a device for producing a three-dimensional shaped object.　A dispersion obtained by dispersing a shaping powder in a solvent is examined for 1H nucleus spin-spin relaxation time T2 using a pulsed NMR device. The specific surface area of the shaping powder is calculated on the basis of the 1H nucleus spin-spin relaxation time T2 of the dispersion and the 1H nucleus spin-spin relaxation time T2 of the solvent. The specific surface area of a shaping powder is apparently increased or reduced by preheating within a powder bed or by heat due to irradiation with laser light or an electron beam. The specific surface area of the shaping powder can hence be used as an index to the degree of deterioration of the shaping powder.

Description

[Technical Field]

[0001] This technology relates to a method and apparatus for measuring the degree of degradation of a molding powder used in additive manufacturing, such as by irradiation with a laser or electron beam; a method and apparatus for manufacturing recycled molding powder; and a method and apparatus for manufacturing a three-dimensional object. This application claims priority based on International Application No. PCT / JP2022 / 040669, filed on 31 October 2022, which is incorporated herein by reference. [Background technology]

[0002] Conventionally, additive manufacturing (ADM) techniques using powders such as resins and metals to produce parts and products are known. For example, the powder bed method involves layering powder, irradiating it with a laser or beam to sinter or melt the powder particles, and repeating this process to create an additive manufacturing structure. The powder bed method allows for a higher density of the manufactured object, making it possible to obtain physical properties similar to those obtained using conventional mass production methods (such as injection molding for resins and casting for metals).

[0003] In additive manufacturing, a portion of the layered powder is sintered or melted using a laser or other means, making it desirable to reuse the powder that is not sintered or melted. For example, Patent Document 1 discloses classifying the powder using a sieve and reusing it. However, simply classifying the powder does not allow for the detection of the degree of powder degradation, which may lead to a decrease in the mechanical properties and dimensional accuracy of the manufactured object. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-050671 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This technology was proposed in light of the conventional situation described above, and provides a method and apparatus for measuring the degree of deterioration of molding powder, a method and apparatus for manufacturing recycled molding powder, and a method and apparatus for manufacturing three-dimensional molded objects, which can suppress the deterioration of the mechanical properties and dimensional accuracy of molded objects. [Means for solving the problem]

[0006] The inventors of this case have developed a method for fabricating powders using pulsed NMR. 1 We found that the specific surface area of ​​the molding powder, determined by measuring the spin-spin relaxation time T2 of the H nucleus, indicates the degree of degradation of the molding powder. This is thought to be because the apparent specific surface area of ​​the molding powder increases or decreases due to preheating in the powder bed and heat generated by irradiation with lasers or electron beams. It should be noted that whether the specific surface area increases or decreases due to the degradation of the molding powder varies depending on the type of molding powder.

[0007] Furthermore, the degree of deterioration of the molding powder to be inspected can be measured based on the specific surface area S1 of the powder obtained by measuring the relaxation time T21 of a reference dispersion in which a standard powder is dispersed, and the specific surface area S2 of the powder obtained by measuring the relaxation time T22 of an inspection dispersion in which the powder to be inspected is dispersed, that is, based on the relaxation time T21 of the reference dispersion and the relaxation time T22 of the inspection dispersion.

[0008] To solve the above problems, this technology provides the following: a method and apparatus for measuring the degree of deterioration of molding powder, a method and apparatus for manufacturing recycled molding powder, and a method and apparatus for manufacturing three-dimensional molded objects.

[0009] [1] Using a pulsed NMR spectrometer, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus is measured, and the inspection dispersion obtained by dispersing the molding powder to be inspected in the solvent is also measured. 1 The spin-spin relaxation time T22 of the H nucleus was measured, The standard dispersion 1The spin-spin relaxation time T21 of the H nucleus and that of the 1 inspection dispersion body, and a method for measuring the degree of deterioration of the powder for shaping to be inspected, which calculates the degree of deterioration of the powder for shaping based on the spin-spin relaxation time T22 of the H nucleus. [2] The method for measuring the degree of deterioration of the powder for shaping according to [1], wherein the powder for shaping is a thermoplastic resin or a metal. [3] The Hansen solubility parameter of the solvent is 14 (J / cm 3 ) 1 / 2 or more and 30 (J / cm 3 ) 1 / 2 or less. The method for measuring the degree of deterioration of the powder for shaping according to [1] or [2]. [4] Using a pulsed NMR apparatus, measure the spin-spin relaxation time T21 of the H nucleus of a reference dispersion in which a reference powder for shaping is dispersed in a solvent, and measure the spin-spin relaxation time T22 of the H nucleus of an inspection dispersion in which a powder for shaping to be inspected is dispersed in the solvent. Calculate the degree of deterioration of the powder for shaping to be inspected based on the spin-spin relaxation time T21 of the H nucleus of the reference dispersion and the spin-spin relaxation time T22 of the H nucleus of the inspection dispersion. An apparatus for measuring the degree of deterioration of the powder for shaping. 1 H nucleus spin-spin relaxation time T21, and measure the 1 H nucleus spin-spin relaxation time T22 of the inspection dispersion in which the powder for shaping to be inspected is dispersed in the solvent, and based on the 1 H nucleus spin-spin relaxation time T21 of the reference dispersion and the 1 H nucleus spin-spin relaxation time T22 of the inspection dispersion, an apparatus for measuring the degree of deterioration of the powder for shaping. [5] The apparatus for measuring the degree of deterioration of the powder for shaping according to [4], wherein the powder for shaping is a thermoplastic resin or a metal. [6] The Hansen solubility parameter of the solvent is 14 (J / cm 3 ) 1 / 2 or more and 30 (J / cm 3 ) 1 / 2 or less. The apparatus for measuring the degree of deterioration of the powder for shaping according to [4] or [5]. [7] Using a pulsed NMR apparatus, measure the spin-spin relaxation time T21 of the H nucleus of a reference dispersion in which a reference powder for shaping is dispersed in a solvent, and measure the spin-spin relaxation time T21 of the H nucleus of an inspection dispersion in which the used powder for shaping to be inspected is dispersed in the solvent. 1 At the same time, measure the spin-spin relaxation time T21 of the H nucleus of the reference dispersion in which the reference powder for shaping is dispersed in the solvent, and measure the spin-spin relaxation time T21 of the H nucleus of the inspection dispersion in which the used powder for shaping to be inspected is dispersed in the solvent. 1The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 The spin-spin relaxation time T21 of the H nucleus and the test dispersion 1 A measurement step for calculating the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, Based on the degree of deterioration of the used molding powder, a production step is made to mix the used molding powder with the unused molding powder to produce recycled molding powder. A method for producing recycled powder for molding. [8] Using a pulsed NMR spectrometer, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent was also measured. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 The spin-spin relaxation time T21 of the H nucleus and the test dispersion 1 A measurement unit that calculates the degree of deterioration of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder. A manufacturing apparatus for recycled powder used in molding, equipped with the following features. [9] Using a pulsed NMR spectrometer, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent was also measured. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 The spin-spin relaxation time T21 of the H nucleus and the test dispersion 1 A measurement step for calculating the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, Based on the degree of deterioration of the used molding powder, a production step is performed to mix the used molding powder with the unused molding powder to produce recycled molding powder. A molding process in which a three-dimensional object is formed by additive manufacturing using the aforementioned recycled powder for molding, A method for manufacturing a three-dimensional object having [the specified characteristics].

[10] Using a pulsed NMR spectrometer, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent was also measured. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 The spin-spin relaxation time T21 of the H nucleus and the test dispersion 1 A measurement unit that calculates the degree of deterioration of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder. A molding unit that forms a three-dimensional object by additive manufacturing using the aforementioned recycled powder for molding, A manufacturing apparatus for three-dimensional objects equipped with the following features.

[11] Using a pulsed NMR spectrometer, a dispersion of molding powder in a solvent is obtained. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A device for measuring the degree of degradation of a molding powder, which calculates the specific surface area of ​​the molding powder based on the spin-spin relaxation time T2 of the H nucleus.

[12] Using a pulsed NMR spectrometer, a dispersion of molding powder in a solvent is obtained. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A method for measuring the degree of degradation of a molding powder, which calculates the specific surface area of ​​the molding powder based on the spin-spin relaxation time T2 of the H nucleus.

[13] The method for measuring the degree of deterioration of a molding powder, wherein the molding powder is a thermoplastic resin or a metal

[12] .

[14] The Hansen solubility parameter of the aforementioned solvent is 14 (J / cm³). 3 ) 1 / 2 More than 30(J / cm 3 ) 1 / 2 The method for measuring the degree of deterioration of molding powder described in

[12] or

[13] below.

[15] The solvent 1 A method for measuring the degree of degradation of a molding powder according to

[12] or

[13] , wherein the spin-spin relaxation time T2 of the H nucleus is 1000 ms or more.

[16] A method for measuring the degree of deterioration of a molding powder, as described in

[12] or

[13] , which calculates the degree of deterioration of a molding powder after use based on the specific surface area of ​​the molding powder before use, which has been measured and calculated in advance.

[17] After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A measurement step for calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, Based on the specific surface area of ​​the used molding powder, a production step is made to mix the used molding powder with the unused molding powder to produce recycled molding powder. A method for producing recycled powder for molding.

[18] After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A measuring unit that calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, Based on the specific surface area of ​​the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder. A manufacturing apparatus for recycled powder used in molding, equipped with the following features.

[19] After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A measurement step for calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, Based on the specific surface area of ​​the used molding powder, a production step is made to mix the used molding powder with the unused molding powder to produce recycled molding powder. A molding process in which a three-dimensional object is formed by additive manufacturing using the aforementioned recycled powder for molding, A method for manufacturing a three-dimensional object having [the specified characteristics].

[20] After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 A measuring unit that calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, Based on the specific surface area of ​​the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder, A molding unit that forms a three-dimensional object by additive manufacturing using the aforementioned recycled powder for molding, A manufacturing apparatus for three-dimensional objects equipped with the following features. [Effects of the Invention]

[0010] This technology allows for the detection of the degree of deterioration of the molding powder, the regeneration of the molding powder, and the suppression of the deterioration of the mechanical properties and dimensional accuracy of the molded object. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a functional block diagram showing an example of a recycled powder manufacturing apparatus to which this technology is applied. [Figure 2] Figure 2 is a flowchart illustrating an example of the operation of a recycled powder manufacturing apparatus to which this technology is applied. [Figure 3] Figure 3 is a schematic cross-sectional view showing an example of a 3D printing apparatus to which this technology is applied. [Figure 4] Figure 4 is a cross-sectional view illustrating the printing operation of a 3D printing apparatus. Figure 4(A) shows the powder supply process, Figure 4(B) shows the powder layer flattening process, Figure 4(C) shows the return process of the flattening roller, and Figure 4(D) shows the printing process for creating the object. [Figure 5] Figure 5 is a graph showing the melt flow rate of PA12 as a function of heating time. [Figure 6] Figure 6 is a graph showing the relaxation time T2 as a function of heating time for PA12. [Modes for carrying out the invention]

[0012] The embodiments of this technology will be described in detail below with reference to the drawings, in the following order. 1. Method and apparatus for measuring the degree of deterioration of molding powder. 2. Method and apparatus for manufacturing recycled powder for molding. 3. Method and apparatus for manufacturing 3D printed objects 4. Examples

[0013] <1. Method and apparatus for measuring the degree of deterioration of molding powder> The method and apparatus for measuring the degree of degradation of a molding powder according to this embodiment uses a pulsed NMR spectrometer to measure the degree of degradation of a dispersion in which the molding powder is dispersed in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1The specific surface area of ​​the molding powder is calculated based on the spin-spin relaxation time T2 of the H nucleus. The specific surface area of ​​the molding powder can be used as an indicator of the degree of degradation of the molding powder, as it appears to increase or decrease due to preheating in the powder bed and heat generated by irradiation with lasers or electron beams.

[0014] Furthermore, the method and apparatus for measuring the degree of degradation of the molding powder according to this embodiment uses a pulsed NMR spectrometer to measure a reference dispersion obtained by dispersing a reference molding powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the inspection dispersion, in which the molding powder to be inspected was dispersed in a solvent, was also measured. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 H nucleus spin-spin relaxation time T21 and test dispersion 1 The degree of degradation of the molding powder being inspected is measured based on the spin-spin relaxation time T22 of the H nucleus.

[0015] [Powder for modeling] The powder used for 3D printing is not particularly limited as long as it is used in 3D printers, and examples include thermoplastic resins and metals. Examples of thermoplastic resins include general-purpose resins and engineering plastics. Examples of general-purpose resins include polypropylene (PP), polyethylene (PE), polyvinyl alcohol (PVA), polyvinylidene chloride (PVDC), and polyethylene terephthalate (PET). Examples of engineering plastics include polyamides (PA) such as nylon 12 (PA12) and nylon 6 (PA6), polycarbonate (PC), fluororesins such as polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE), liquid crystal polymers (LCP), polyamide-imide (PAI), and polyetherimide (PEI). Examples of metals include titanium, aluminum, stainless steel, cobalt-chromium, nickel alloys, and copper alloys.

[0016] The average particle size of the powder particles is preferably between 10 μm and 200 μm. The average particle size can be determined by measuring 200 or more particles using a microscope (optical microscope, metallurgical microscope, electron microscope, etc.) and taking the average value.

[0017] [solvent] The solvent can be appropriately selected depending on the molding powder, for example, based on the Hansen solubility parameter (HSP) of the solvent. The lower limit of the Hansen solubility parameter (HSP) of the solvent is preferably 5 (J / cm²). 3 ) 1 / 2 More preferably 10 (J / cm²) 3 ) 1 / 2 More preferably 14 (J / cm) 3 ) 1 / 2 The above conditions apply, and the lower limit of the HSP of the solvent is preferably 40 (J / cm²). 3 ) 1 / 2 More preferably, 35 (J / cm²) 3 ) 1 / 2 More preferably, 30 (J / cm²) 3 ) 1 / 2 The following applies. In particular, the HSP of the solvent is 14 (J / cm³). 3 ) 1 / 2 More than 30(J / cm 3 ) 1 / 2 The following conditions allow for excellent dispersibility of the molding powder and enable comparison of the degree of degradation.

[0018] The Hansen solubility parameter (δ) consists of three parameters: the dispersion term δd, the polarity term δp, and the hydrogen bonding term δh, and is expressed by the following equation (1).

[0019] δ 2 =δd 2 + δp 2 + δh 2 (1) δd: Energy due to intermolecular dispersion forces δp: Energy due to intermolecular dipole interaction δh: Energy due to intermolecular hydrogen bonding

[0020] Furthermore, the Hansen solubility parameters (δ, δd, δp, δh) can be used directly from the values ​​included in the computer software Hansen Solubility Parameters in Practice 4th Edition 4.1.07 (HSPiP).

[0021] Examples of Hansen solubility parameters (δ, δd, δp, δh) for solvents shown as specific examples include: ethanol (δ:26.5, δd:15.8, δp:8.8, δh:19.4), DPG (dipropylene glycol, SP:26.4, δd:16.5, δp:10.6, δh:17.7), butanol (δ:23.2, δd:16, δp:5.7, δh:15.8), DMAC (dimethylacetamide, SP:22.4, δd:16.8, δp:11.5, δh:9.4), ethyl lactate (δ:21.7, δd:16, δp:7.6, δh:12.5), and acetic acid. Examples include (δ:21.4, δd:14.5, δp:8, δh:13.5), cyclohexanone (SP:20.3, δd:17.8, δp:8.4, δh:5.1), acetone (δ:20, δd:15.5, δp:10.4, δh:7), toluene (δ:18.2, δd:18, δp:1.4, δh:2), MCH (methylcyclohexane, SP:16, δd:16, δd:0, δh:1), hexane (δ:14.9, δd:14.9, δp:0, δh:0), and NMP (N-methyl 2-pyrrolidone, δd:18.0, δp:12.3, δh:7.2).

[0022] [Specific surface area measured using pulsed NMR] Pulsed NMR (Nuclear Magnetic Resonance) is an index for evaluating molecular mobility. 1 This method is specifically designed to obtain the relaxation time (suvyn-lattice relaxation time T1) and spin-spin relaxation time T2 of the H nucleus. 1 The spin-spin relaxation time T2 of the H nucleus is called the "transverse relaxation time" or simply "relaxation time T2". The transverse relaxation time can be measured, for example, using the Acorn area pulsed NMR spectrometer manufactured by Xigo nanotools.

[0023] As the pulse sequence in pulse NMR measurement, for example, it can be appropriately selected from the Hahn echo method, solid echo method, CPMG method (Carr-Purcell-Meiboom-Gill method), 90° pulse method, etc. When it is expected that the influence of the diffusion of the powder for shaping is large, it is preferable to apply the CPMG method. The CPMG method repeats spin echoes by continuous 180° pulses at a constant interval and fixes the magnetization on the xy plane of the rotating coordinate system. Since the total sum of the transverse magnetization decreases due to the T2 relaxation during this period, the transverse relaxation time can be measured.

[0024] The specific surface area of the powder obtained by measuring the relaxation time T2 of the dispersion of the powder using pulse NMR can be used as an index of the degree of deterioration of the powder. This is considered to be because the apparent specific surface area of the powder increases or decreases due to preheating in the powder bed or heat when irradiated with a laser or an electron beam. Thereby, the degree of deterioration of the powder can be detected and the powder can be regenerated.

[0025] The specific surface area is the surface area per unit mass of the powder, and for the same mass, the finer the particles, the larger it is. The specific surface area can be converted from the relaxation time T-2 in pulse NMR measurement by the following formula (2). R av =Ψ p SLρ<000�088>(R s -R b )+R[[ID=*23]] b (2) R av : Average relaxation rate of the dispersion (reciprocal of the relaxation time) Ψ p : Ratio of particle volume to solvent volume S: Surface area per unit mass (specific surface area) L: Thickness of the solvent constrained on the particle surface ρ p : Particle density R s : Relaxation rate of the solvent constrained on the particle interface (reciprocal of the relaxation time) R b: Relaxation rate (reciprocal of relaxation time) of the solvent in the free state (bulk state)

[0026] Here, if Ka is defined by the following formula (3), the specific surface area S is expressed by the following formula (4). Ka = Lρ p (R s -R b ) (3)

[0027] S = (R av -R b ) / KaΨ p (4) Ka can be calculated using the specific surface area actually in contact with the solvent. For example, in the case of silica, the area actually in contact with the liquid can be obtained by using the shear method. Also, as an estimation method, it may be calculated from particle size measurement by dynamic light scattering method, centrifugal sedimentation method, laser diffraction method, microscope, etc.

[0028] Also, Ψ p can be calculated by the following formula (5).

[0029] Ψ p = (S c / S d ) / [(1 - S c ) / T d (5) In the formula, S c is the solid content concentration (mass%) of the powder of the dispersion, S d is the density of the powder (g / cm 3 ), and T d is the density of the solvent (g / cm 3 ).

[0030] That is, if the relaxation time T2 (reciprocal of R b ) of the solvent is known, the specific surface area S can be obtained from the relaxation time T2 (reciprocal of R av ) in the system containing powder particles.

[0031] Furthermore, the ratio of the specific surface area S1 of the powder obtained by measuring the relaxation time T21 of the reference dispersion in which the standard powder is dispersed, to the specific surface area S2 of the powder obtained by measuring the relaxation time T22 of the inspection dispersion in which the powder to be inspected is dispersed, can be calculated by the following formula (6). S2 / S1=(R av2 -R b ) / (R av1 -R b ) (6)

[0032] In other words, the degree of deterioration of the molding powder to be inspected can be measured based on the relaxation time T21 of the reference dispersion and the relaxation time T22 of the inspection dispersion. For example, the degree of deterioration can be calculated by the ratio of the relaxation time T21 of the reference dispersion to the relaxation time T22 of the inspection dispersion. Specifically, the degree of deterioration may be calculated by the ratio of the relaxation time T22 of the inspection dispersion to the relaxation time T21 of the reference dispersion (T22 / T21), and based on the specific surface area ratio S2 / S1 (R av2 -R b ) / (R av1 -R b ), R av2 / R av1 You can also calculate (=T21 / T22).

[0033] Generally, the movement of liquid molecules adsorbed on a particle surface is restricted, while liquid molecules in the bulk liquid can move freely. As a result, the lateral relaxation time of liquid molecules adsorbed on a particle surface is shorter than the lateral relaxation time of liquid molecules in the bulk liquid.

[0034] The larger the volume fraction Ps of the dispersion medium adsorbed on the particle surface, the shorter the lateral relaxation time. Therefore, the larger the total surface area of ​​the particles, the shorter the lateral relaxation time. Consequently, the larger the specific surface area of ​​the particles, the shorter the lateral relaxation time tends to be, and the smaller the particle diameter, the shorter the lateral relaxation time tends to be. Also, the larger the number of particles, the shorter the lateral relaxation time tends to be.

[0035] Furthermore, the stronger the interaction between the particles and the dispersion medium, the shorter the lateral relaxation time. In other words, the higher the affinity between the particles and the dispersion medium, the shorter the lateral relaxation time. The affinity between the particles and the dispersion medium can be adjusted, for example, by the type and number of functional groups on the surface of the particles, or by the compounds incorporated into the dispersion medium.

[0036] The lower limit of the transverse relaxation time of the dispersion medium measured using a pulsed NMR spectrometer is preferably 50 ms or more, more preferably 500 ms or more, and even more preferably 1000 ms or more. The upper limit of the transverse relaxation time of the dispersion medium measured using a pulsed NMR spectrometer is preferably 5000 ms or less, more preferably 3000 ms or less, and even more preferably 2500 ms or less. This makes it possible to increase the ratio of the specific surface area of ​​the powder to the specific surface area of ​​the solvent.

[0037] <2. Method and apparatus for manufacturing recycled powder for molding> The method for producing recycled molding powder according to this embodiment involves sampling the used molding powder and using a pulsed NMR spectrometer to obtain a dispersion obtained by dispersing the used molding powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 The process includes a measurement step of calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and a production step of mixing the used molding powder with the unused molding powder based on the specific surface area of ​​the used molding powder to generate recycled molding powder.

[0038] Furthermore, the method for producing the recycled powder for molding according to this embodiment involves using a pulsed NMR spectrometer to disperse a reference dispersion of the reference powder in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the test dispersion was obtained by dispersing the used molding powder to be tested in a solvent. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 H nucleus spin-spin relaxation time T21 and test dispersion 1The system includes a measurement step for calculating the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, and a production step for mixing the used molding powder with the unused molding powder to generate recycled molding powder based on the degree of degradation of the used molding powder.

[0039] The manufacturing apparatus for recycled molding powder according to this embodiment samples used molding powder and uses a pulsed NMR spectrometer to disperse the used molding powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 The system includes a measuring unit that calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and a generating unit that mixes the used molding powder with the unused molding powder based on the specific surface area of ​​the used molding powder to generate recycled molding powder.

[0040] Furthermore, the manufacturing apparatus for recycled powder for molding according to this embodiment uses a pulsed NMR spectrometer to disperse a reference dispersion of a reference powder for molding in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the test dispersion was obtained by dispersing the used molding powder to be tested in a solvent. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 H nucleus spin-spin relaxation time T21 and test dispersion 1 The system includes a measurement unit that calculates the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, and a generation unit that mixes the used molding powder with the unused molding powder based on the degree of degradation of the used molding powder to generate recycled molding powder.

[0041] According to this embodiment, for example, the degree of deterioration of the molding powder after use can be calculated by using the specific surface area of ​​the molding powder before use, which has been measured and calculated in advance, as a reference, and the degree of deterioration of the molding powder after use can be calculated by using the relaxation time T21 of the reference powder and the relaxation time T22 of the molding powder to be inspected as a reference, thereby enabling the calculation of the mixing ratio of the molding powder after use and the degree of deterioration of the molding powder after mixing. As a result, recycled molding powder having a predetermined degree of deterioration (specific surface area) can be manufactured.

[0042] [Equipment for manufacturing recycled powder] Figure 1 is a functional block diagram showing an example of a recycled powder manufacturing apparatus to which this technology is applied. As shown in Figure 1, the recycled powder manufacturing apparatus 10 includes a powder recovery unit 11 for recovering used powder, a sieve mesh classification unit 12 for sieving the powder, a measurement unit 13 for measuring the degree of deterioration of the powder, a powder supply unit 14 for supplying new powder, a mixing unit 15 for mixing the powder that has passed through the sieve mesh with the new powder, an output unit 16 for outputting recycled powder, and a control unit 17 for controlling the amount of new powder supplied from the powder supply unit 14 to the mixing unit 15. Note that if, for example, powder that has not been preheated in a powder bed or affected by heat from a laser or electron beam is used as the used powder, the sieve classification unit 12 may be omitted.

[0043] The powder recovery unit 11 recovers powder used in the 3D printing apparatus 20, which will be described later. For example, it may recover powder 41 from the printing tank 40 that did not become part of the 3D printing apparatus 20, or it may recover powder 51 from the recovery tank 50. Examples of powder transport methods for recovery include a screw conveyor system using a screw or an air transport system using air.

[0044] The sieve mesh classification unit 12 classifies the used powder recovered in the powder recovery unit 11 using a sieve mesh. This separates the used powder into fine powder, which consists of fine particles that pass through the sieve mesh, and coarse powder, which consists of coarse particles remaining on the sieve mesh. The coarse powder may be discarded, or it may be crushed in a ball mill or the like to extract the fine particles by airflow classification and return it to the powder recovery unit 11.

[0045] The measurement unit 13 samples a portion of the powder that has passed through the sieve and measures the degree of powder degradation. Specifically, it uses a pulsed NMR spectrometer to measure the dispersion of powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the specific surface area of ​​the powder is calculated. The calculation result of the specific surface area is transmitted to the control unit 17. Alternatively, the measurement unit 13 may sample the mixed powder from the mixing unit 15, calculate the specific surface area of ​​the mixed powder using a pulsed NMR spectrometer, and transmit the calculation result to the control unit 17.

[0046] The powder supply unit 14 stores new powder and supplies a predetermined amount of new powder, as notified by the control unit 17, to the mixing unit 15. The mixing unit 15 mixes the powder that has passed through the sieve of the sieve classification unit 12 with the new powder supplied from the powder supply unit 14. The output unit 16 outputs the powder mixed in the mixing unit 15 as usable recycled powder. For example, the output unit 16 outputs the recycled powder to the powder tank 30 of the 3D molding apparatus 20, which will be described later.

[0047] The control unit 17 controls the processing of each part. Specifically, the control unit 17 controls the amount of new powder supplied from the powder supply unit 14 to the mixing unit 15 based on the specific surface area calculated by the measuring unit 13. The control unit 17 may, for example, determine a first supply amount of new powder based on the specific surface area of ​​the powder that has passed through the sieve, and then determine a second supply amount of new powder based on the specific surface area of ​​the powder after mixing. The control unit 17 also controls the amount of used powder supplied to the sieve classification unit 12.

[0048] [Operation of the recycled powder manufacturing equipment] Next, the operation of the recycled powder manufacturing apparatus will be explained with reference to Figures 1 and 2. Figure 2 is a flowchart illustrating an example of the operation of a recycled powder manufacturing apparatus to which this technology is applied.

[0049] As shown in Figure 2, first, in step S1, the powder recovery unit 11 recovers, for example, the powder 41 from the molding tank 40 and the powder 51 from the recovery tank 50 that did not become part of the 3D molding apparatus 20 described later.

[0050] In step S2, the sieve classification unit 12 classifies the used powder recovered in the powder recovery unit 11 using a sieve. This separates the used powder into fine powder, which consists of fine particles that pass through the sieve, and coarse powder, which consists of coarse particles remaining on the sieve. The coarse powder may be discarded, or it may be crushed in a ball mill or the like to extract the fine particles by airflow classification and return it to the powder recovery unit 11.

[0051] In step S3, the measurement unit 13 samples a portion of the fine powder that passed through the sieve in step S2, and uses a pulsed NMR spectrometer to analyze the dispersion obtained by dispersing the used powder in the solvent. 1 The spin-spin relaxation time T2 of the H nucleus is measured, and the specific surface area of ​​the used powder is calculated. Based on the specific surface area of ​​the used powder, the control unit 17 calculates a first supply amount of new powder to be supplied from the powder supply unit 14 to the mixing unit 15.

[0052] In step S4, the powder supply unit 14 supplies a first supply amount of new powder calculated by the control unit 17 to the mixing unit 15, and the mixing unit 15 mixes the powder that has passed through the sieve of the sieve classification unit 12 with the new powder supplied from the powder supply unit 14. Alternatively, the measurement unit 13 may sample a portion of the mixed powder in the mixing unit 15 and calculate the specific surface area of ​​the mixed powder using a pulsed NMR spectrometer. The control unit 17 may then calculate a second supply amount of new powder based on the specific surface area of ​​the mixed powder and have the powder supply unit 14 supply the new powder to the mixing unit 15. The output unit 16 outputs the powder mixed in the mixing unit 15 as usable recycled powder, for example, to the powder tank 30 of the 3D molding apparatus 20, which will be described later.

[0053] As described above, recycled powder having a predetermined specific surface area can be produced by mixing used powder with new powder, based on the specific surface area of ​​the used powder calculated using a pulsed NMR spectrometer.

[0054] In the recycled powder manufacturing apparatus described above, the measurement unit 13 calculates the specific surface area of ​​the powder, and the control unit 17 controls the supply amount of new powder based on the specific surface area, but this is not the only option. For example, the degree of deterioration of the used molding powder may be calculated based on the relaxation time T21 of a standard powder and the relaxation time T22 of the used powder to be inspected, and the control unit 17 may control the supply amount of new powder based on the degree of deterioration of the used molding powder.

[0055] <3. Method and apparatus for manufacturing three-dimensional objects> The method for manufacturing a three-dimensional object according to this embodiment involves sampling the used molding powder and using a pulsed NMR spectrometer to obtain a dispersion of the used molding powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1The process includes a measurement step of calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus; a production step of mixing the used molding powder with the unused molding powder based on the specific surface area of ​​the used molding powder to generate recycled molding powder; and a molding step of forming a three-dimensional object by additive manufacturing using the recycled molding powder.

[0056] Furthermore, the manufacturing method of the three-dimensional object according to this embodiment involves using a pulsed NMR spectrometer to disperse a reference dispersion of a reference powder used for 3D printing in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the test dispersion was obtained by dispersing the used molding powder to be tested in a solvent. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 H nucleus spin-spin relaxation time T21 and test dispersion 1 The process includes a measurement step of calculating the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus; a production step of mixing the used molding powder with the unused molding powder based on the degree of degradation of the used molding powder to generate recycled molding powder; and a molding step of forming a three-dimensional object by additive manufacturing using the recycled molding powder.

[0057] The three-dimensional object manufacturing apparatus according to this embodiment samples the used molding powder and uses a pulsed NMR spectrometer to analyze the dispersion obtained by dispersing the used molding powder in a solvent. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 The system includes a measuring unit that calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, a generating unit that mixes the used molding powder with the unused molding powder based on the specific surface area of ​​the used molding powder to generate recycled molding powder, and a molding unit that forms a three-dimensional object by additive manufacturing using the recycled molding powder.

[0058] Furthermore, the manufacturing apparatus for three-dimensional objects according to this embodiment uses a pulsed NMR spectrometer to disperse a reference dispersion of a reference powder used for manufacturing in a solvent. 1 The spin-spin relaxation time T21 of the H nucleus was measured, and the test dispersion was obtained by dispersing the used molding powder to be tested in a solvent. 1 The spin-spin relaxation time T22 of the H nucleus was measured, and the reference dispersion was measured. 1 H nucleus spin-spin relaxation time T21 and test dispersion 1 The system includes a measurement unit that calculates the degree of degradation of the used molding powder based on the spin-spin relaxation time T22 of the H nucleus, a generation unit that mixes the used molding powder with the unused molding powder based on the degree of degradation of the used molding powder to generate recycled molding powder, and a molding unit that forms a three-dimensional object by additive manufacturing using the recycled molding powder.

[0059] According to this embodiment, since a three-dimensional object is additively fabricated using recycled powder for molding having a predetermined degree of degradation (specific surface area), it is possible to suppress the deterioration of the mechanical properties and dimensional accuracy of the fabricated object due to powder degradation.

[0060] Examples of additive manufacturing methods for 3D printing systems include selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM). Generally, SLS is used when the material used for manufacturing is resin, while SLS, SLM, and EBM are used when the material used for manufacturing is metal.

[0061] The following describes a powder bed type 3D printing apparatus, which uses a powder bed to form a thin layer of molding powder, and then scans it with a laser or electron beam to create the cross-sectional shape of the object.

[0062] [3D printing equipment] Figure 3 is a cross-sectional view showing a schematic example of a 3D printing apparatus to which this technology is applied. Figure 4 is a cross-sectional view illustrating the printing operation of the 3D printing apparatus, where Figure 4(A) shows the powder supply process, Figure 4(B) shows the powder layer planarization process, Figure 4(C) shows the planarization roller return process, and Figure 4(D) shows the printing process for creating the object.

[0063] The 3D modeling apparatus 20 comprises a powder tank 30 for supplying powder, a molding tank 40 for molding objects, and a recovery tank 50 for recovering powder. The 3D modeling apparatus 20 also includes a molding unit 70 that emits laser light 71 to form a molding layer 60 on a powder layer 61 and then builds a three-dimensional object by stacking the molding layers 60. The 3D modeling apparatus 20 may also include the aforementioned recycled powder manufacturing apparatus 10, supplying recycled powder output from the output unit 16 to the powder tank 30, supplying powder 41 from the molding tank 40 that did not become a molded object to the powder recovery unit 11, or supplying powder 51 from the recovery tank 50 to the powder recovery unit 11. Examples of powder transport methods for supplying powder include a screw conveyor system using a screw and an air transport system using air.

[0064] The flattening roller 21 is a flattening means (recoater) that moves reciprocally relative to the upper surface of the molding tank 40, transferring and supplying the powder 31 from the powder tank 30 to the molding tank 40, flattening the powder 41 in the molding tank 40 to form a powder layer 61, and recovering the powder 51 in the recovery tank 50. Alternatively, a flattening means such as a plate-shaped member (blade) may be used instead of the flattening roller 21.

[0065] The powder tank 30 has an open top and is box-shaped, holding the powder 31 to be supplied to the molding tank 40. It is equipped with a supply stage 32 at the bottom. The supply stage 32 moves up and down vertically (height direction), and by raising it in the direction of arrow Z1, the powder 31 on the top surface is transferred and supplied by the flattening roller 21. Here, the powder 31 may be recycled powder output from the output unit 16 of the recycled powder manufacturing apparatus 10 described above.

[0066] The molding tank 40 has a box-like shape with an open top to hold the powder 41 used to form the object, and is equipped with a molding stage 42 at its bottom. The molding stage 42 moves up and down vertically (height direction) and is lowered by △t1 in the direction of arrow Z2 to form a powder layer 61 on its upper surface. The molding tank 40 also forms a molded layer 60 on the powder layer 61 by emitting laser light 71 from the molding unit 70, and forms a three-dimensional object by stacking the molded layers 60. The powder 41 in the molding tank 40 that does not become a molded object may be recovered as used powder in the powder recovery unit 11 of the recycled powder manufacturing apparatus 10 described above.

[0067] The recovery tank 50 stores excess powder 51 that does not form the powder layer 61, which is supplied by the flattening roller 21 when forming the powder layer 61 on the upper surface of the molding tank 40. The powder 51 in the recovery tank 50 may be recovered as used powder in the powder recovery section 11 of the recycled powder manufacturing apparatus 10 described above.

[0068] The molding unit 70 emits laser light 71 onto the powder layer 61 on the molding stage 42, and the entire molding unit 70 moves back and forth in the Y direction, which is perpendicular to the X direction.

[0069] [Shaping motion] Next, the printing operation of the 3D printing apparatus will be explained with reference to Figures 3 and 4. Here, the explanation will begin from the state in which the first layer 60 is formed on the printing stage 42 of the printing tank 40, as shown in Figures 3 and 4(A).

[0070] As shown in Figures 3 and 4(A), when forming the second layer 60, the supply stage 32 of the supply tank 30 is raised in the Z1 direction, and the molding stage 42 of the molding tank 40 is lowered in the Z2 direction. At this time, the lowering distance of the molding stage 42 is set so that the distance between the surface of the first powder layer and the lower part (lower tangential part) of the flattening roller 21 is △t1. This distance △t1 corresponds to the thickness (layer pitch) of the second powder layer 61. The distance △t1 is preferably about 1 to 100 μm.

[0071] Next, as shown in Figure 4(B), the powder 31 located on the upper surface of the supply tank 30 is moved in the Y1 direction (towards the molding tank 40) while the flattening roller 21 is rotated, thereby transferring and supplying the powder 31 to the molding tank 40 (powder supply process).

[0072] Furthermore, as shown in Figure 4(B), the flattening roller 21 is moved parallel to the stage surface of the molding stage 42 of the molding tank 40, and the powder 41 is supplied to the molding tank 40 while being flattened (flattening process). As a result, as shown in Figure 4(C), a powder layer 61 with a predetermined thickness △t1 is formed on the molding stage 42 of the molding tank 40. At this time, any excess powder 51 that was not used to form the powder layer 61 falls into the recovery tank 50.

[0073] After the powder layer 61 is formed, the flattening roller 21 is transported in the Y2 direction and returned to its initial position (origin position) as shown in Figure 4(C) (return process).

[0074] Subsequently, as shown in Figure 4(D), a laser beam 71 is emitted from the molding unit 70 to form a molded layer 60 in the powder layer 61 (molding process). The molded layer 60 is formed, for example, when the powder layer 61 is heated by the laser beam 71, causing the powder to sinter or melt.

[0075] Thereafter, by repeating the aforementioned powder supply process, flattening process, restoration process, and molding process the required number of times, a three-dimensional object can be manufactured by stacking molding layers 60. Here, after the completion of the three-dimensional object, the powder 41 remaining in the molding tank 40 and the powder 51 recovered in the recovery tank 50 are supplied to the powder recovery section 11 of the recycled powder manufacturing device 10, and the recycled powder output from the output section 16 is supplied to the supply tank 30, thereby suppressing the deterioration of the mechanical properties and dimensional accuracy of the object due to powder degradation. [Examples]

[0076] <4. Examples> In this example, the molding powder was dispersed in various solvents, and the specific surface area of ​​the molding powder was calculated using a pulsed NMR spectrometer.

[0077] The following materials were prepared for molding: PA12 (Nylon 12 (polyamide), average particle size 60 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer) • Refurbished product (a mixture of new and used powder, new:used = 20:80 (by mass)) PP (Polypropylene, average particle size 51 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer) • Refurbished product (a mixture of new and used powder, new:used = 20:80 (by mass)) Titanium (average particle size 10-85 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer)

[0078] The following solvents were prepared. Ethanol (δ: 26.5, δd: 15.8, δp: 8.8, δh: 19.4) DPG (Dipropylene Glycol, SP: 26.4, δd: 16.5, δp: 10.6, δh: 17.7) Butanol (δ: 23.2, δd: 16, δp: 5.7, δh: 15.8) DMAC (dimethylacetamide, SP: 22.4, δd: 16.8, δp: 11.5, δh: 9.4) Ethyl lactate (δ: 21.7, δd: 16, δp: 7.6, δh: 12.5) Acetic acid (δ:21.4, δd:14.5, δp:8, δh:13.5) Cyclohexanone (SP: 20.3, δd: 17.8, δp: 8.4, δh: 5.1) Acetone (δ:20, δd:15.5, δp:10.4, δh:7) Toluene (δ:18.2, δd:18, δp:1.4, δh:2) MCH (methylcyclohexane, SP:16, δd:16, δd:0, δh:1) Hexane (δ: 14.9, δd: 14.9, δp: 0, δh: 0)

[0079] [Pulsed NMR Measurement] Using a pulsed NMR spectrometer (Acorn area, manufactured by Xigo nanotools), the dispersion of the molding powder in the solvent was analyzed. 1 The spin-spin relaxation time T2 of the H nucleus was measured, and the dispersion... 1 The spin-spin relaxation time T2 of the H nucleus and the solvent 1 The specific surface area of ​​the molding powder was calculated based on the spin-spin relaxation time T2 of the H nucleus. The specific surface area was calculated using the following equation (4) mentioned above. S=(R av -R b ) / KaΨ p (4) R av : The average relaxation rate of the dispersion (the reciprocal of the dispersion's relaxation time T2) Ψ p : Particle volume ratio to solvent volume S: Surface area per unit mass (specific surface area) R b : The relaxation rate of a solvent in a free state (bulk state) (the reciprocal of the solvent relaxation time T2). In this example, since the specific surface area is evaluated as a relative value between a new product and a used product, the Ka value in the calculation of the specific surface area was set to a constant value of 0.000312, and the Ψp value was set to a constant value of 1 (solvent volume = particle volume).

[0080] Measurements using a pulsed NMR spectrometer were performed under the following conditions. Pulse sequence: CPMG method Resonance frequency: 13MHz Bulk Relaxation Time:2600.0ms Specific Surface Relaxivity:0.000264 g / m 2 / ms Measurement temperature: 25℃ Quantity of sample to be measured: 1.0 cm 3 Time from mixing to measurement: 3 min

[0081] In this example, the specific surface area of ​​the solvent was calculated using the following formula (4-1), and the specific surface area of ​​the dispersion was calculated using the following formula (4-2). SA(solvent) = (1 / T2(solvent) - 1 / 2600) / 0.000312 (4-1) SA(dispersion) = (1 / T2(dispersion) - 1 / T2(solvent)) / 0.000312 (4-2) SA: specific surface area T2: Spin-spin relaxation time T2 of 1H nucleus [ms]

[0082] [Measurement Example 1] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and ethanol as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0083] [Measurement Example 2] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and DPG (dipropylene glycol) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0084] [Measurement Example 3] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and butanol as the solvent. The relaxation time T2 of the solvent and dispersion was then measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0085] [Measurement Example 4] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and DMAC (dimethylacetamide) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0086] [Measurement Example 5] Dispersions were prepared using PA12 (new and used) as the molding powder and acetic acid as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0087] [Measurement Example 6] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and cyclohexane as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0088] [Measurement Example 7] Dispersions were prepared using PA12 (new and used) as the molding powder and acetone as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0089] [Measurement Example 8] Dispersions were prepared using PA12 (new and used) as the molding powder and toluene as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0090] [Measurement Example 9] Dispersions were prepared using PA12 (new, used, and recycled) as the molding powder and MCH (methylcyclohexane) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0091] [Measurement Example 10] Dispersions were prepared using PA12 (new and used) as the molding powder and hexane as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0092] [Measurement Example 11] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and DPG (dipropylene glycol) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0093] [Measurement Example 12] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and DMAC (dimethylacetamide) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0094] [Measurement Example 13] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and ethyl lactate as the solvent. The relaxation time T2 of the solvent and dispersion was then measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0095] [Measurement Example 14] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and cyclohexanone as the solvent. The relaxation time T2 of the solvent and dispersion was then measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0096] [Measurement Example 15] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and MCH (methylcyclohexane) as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0097] [Measurement Example 16] Dispersions were prepared using PP (new, used, and recycled) as the molding powder and hexane as the solvent. Then, the relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated.

[0098] [Measurement Example 17] Dispersions were prepared using titanium (new and used) as the molding powder and DPG (dipropylene glycol) as the solvent. The relaxation time T2 of the solvent and dispersion was measured using a pulsed NMR spectrometer, and the specific surface area was calculated. The used titanium was measured after being sieved 10 times.

[0099] Table 1 shows the pulsed NMR measurement results for Measurement Example 1 to Measurement Example 17. In Table 1, T2 is 1 T2 is the spin-spin relaxation time of the H nucleus, SA is the specific surface area, the solvent ratio is the ratio of the solvent to SA, and the new powder ratio is the ratio of the new powder to SA.

[0100] [Table 1]

[0101] As shown in Table 1, it was found that the specific surface area of ​​the molding powder (new, used, and recycled) can be calculated using a pulsed NMR spectrometer, and that this can be used as an indicator of the degree of degradation of the molding powder. The solvent had a Hansen solubility parameter of 14 (J / cm²). 3 ) 1 / 2 More than 30(J / cm 3 ) 1 / 2 It was found that various materials could be used. Furthermore, it was discovered that by setting the solvent relaxation time T2 to 1000 ms or more, it was possible to increase the ratio of the specific surface area of ​​the powder to the specific surface area of ​​the solvent.

[0102] Furthermore, it was found that the specific surface area decreased due to powder degradation in PA12 and titanium, but increased in PP due to powder degradation. It was also found that it is preferable to calculate the degree of degradation of the molding powder after use (used product) and recycled product using the specific surface area of ​​the molding powder before use (new product), which has been measured and calculated in advance, as a baseline (e.g., 100%).

[0103] Furthermore, the following molding powders were dispersed in a solvent, and the relaxation time T2 [ms] of the molding powders was measured using a pulsed NMR spectrometer. The ratio (T21 / T22, T22 / T21) of the relaxation time T21 of the reference molding powder and the relaxation time T22 of the molding powder to be tested was calculated.

[0104] The following materials were prepared for molding: PA12 (Nylon 12 (polyamide), average particle size 60 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer) PA11 (Nylon 11 (polyamide), average particle size 60 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer) PA6 (Nylon 6 (polyamide), average particle size 50 μm) • Refurbished product (a mixture of new and used powder, new:used = 20:80 (by mass)) • Used materials (printing powder used in a 3D printer) PPS (Polyphenylene sulfide, average particle size 50 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer) Titanium (average particle size 10-85 μm) • Brand new (unused 3D printing powder, not yet used in a 3D printer) • Used materials (printing powder used in a 3D printer)

[0105] The following solvents were prepared. NMP (N-methyl-2-pyrrolidone, δd: 18.0, δp: 12.3, δh: 7.2)

[0106] [Measurement Example 18] Dispersion A (new) and dispersion B (used) were prepared using PA12 (new and used) as the molding powder and NMP (N-methyl 2-pyrrolidone) as the solvent. The relaxation time T2 of dispersion A (new) and dispersion B (used) was measured using a pulsed NMR spectrometer, and their ratio was calculated.

[0107] [Measurement Example 19] Dispersion A (new) and dispersion B (used) were prepared using PA11 (new and used) as the molding powder and NMP (N-methyl 2-pyrrolidone) as the solvent. The relaxation time T2 of dispersion A (new) and dispersion B (used) was measured using a pulsed NMR spectrometer, and their ratio was calculated.

[0108] [Measurement Example 20] Dispersion A (recycled) and dispersion B (used) were prepared using PA6 (recycled and used) as the molding powder and NMP (N-methyl 2-pyrrolidone) as the solvent. The relaxation time T2 of dispersion A (recycled) and dispersion B (used) was measured using a pulsed NMR spectrometer, and their ratio was calculated.

[0109] [Measurement Example 21] Dispersion A (new) and dispersion B (used) were prepared using PPS (new and used) as the molding powder and NMP (N-methyl 2-pyrrolidone) as the solvent. The relaxation time T2 of dispersion A (new) and dispersion B (used) was measured using a pulsed NMR spectrometer, and their ratio was calculated.

[0110] [Measurement Example 22] Dispersion A (new) and dispersion B (used) were prepared using titanium (new and used) as the molding powder and NMP (N-methyl 2-pyrrolidone) as the solvent. The relaxation time T2 of the solvent and dispersion was then measured using a pulsed NMR spectrometer. The used titanium was measured after being sieved 10 times.

[0111] [Measurement Example 23] Dispersion A (new) and dispersion B (used) were prepared using PA12 (new and used) as the molding powder and a mixed solvent of NMP (N-methyl 2-pyrrolidone):ethyl lactate = 9:1 as the solvent. The relaxation time T2 of dispersion A (new) and dispersion B (used) was then measured using a pulsed NMR spectrometer, and their ratio was calculated.

[0112] Table 2 shows the pulsed NMR measurement results for measurement examples 18-23. In Table 1, T2A is the result of dispersion A. 1 T2 [ms] is the spin-spin relaxation time of the H nucleus, and T2B is the spin-spin relaxation time of dispersion B. 1 This is the spin-spin relaxation time T2 [ms] of the H nucleus.

[0113] [Table 2]

[0114] As shown in Measurement Examples 18-23, even when NMP (N-methyl 2-pyrrolidone) is used as the solvent, the relaxation time T2 of the reference dispersion A and the dispersion B under test can be measured, and the degree of degradation of the molding powder under test can be calculated. Furthermore, as shown in Measurement Example 23, even when a mixed solvent of NMP and ethyl lactate is used, the relaxation time T2 of the reference dispersion A and the dispersion B under test can be measured, and the degree of degradation of the molding powder under test can be calculated.

[0115] [Correlation with other measurement methods] Figure 5 is a graph showing the melt flow rate of PA12 as a function of heating time, and Figure 6 is a graph showing the relaxation time T2(NMP) of PA12 as a function of heating time. PA12 powder was heated at 175°C, and the melt flow rate and relaxation time T2(NMP) were measured for samples after a predetermined time. In the melt flow rate measurement, the melt flow rate decreased with heating time, and in the relaxation time T2 measurement, the relaxation time T2 increased with heating time. As can be seen by comparing the graphs shown in Figure 5 and Figure 6, the relaxation time T2 measurement shows a high correlation with the melt flow rate measurement. It should be noted that the heating degradation of PA12 powder is thought to be due to an increase in molecular weight inside the powder and modification of the powder surface. [Explanation of symbols]

[0116] 10 Recycled powder manufacturing apparatus, 11 Powder recovery unit, 12 Sieve mesh classification unit, 13 Measurement unit, 14 Powder supply unit, 15 Mixing unit, 16 Output unit, 17 Control unit, 20 3D molding apparatus, 21 Flattening roller, 30 Powder tank, 31 Powder, 40 Molding tank, 41 Powder, 50 Recovery tank, 51 Powder

Claims

1. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure, The standard dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A method for measuring the degree of deterioration of molding powder, which is subject to inspection, based on the above.

2. The method for measuring the degree of deterioration of a molding powder according to claim 1, wherein the molding powder is a thermoplastic resin or a metal.

3. The Hansen solubility parameter of the solvent is 14 (J / cm ３ ), １／２ or more and 30 (J / cm ３ ), １／２ The method for measuring the degree of deterioration of the powder for shaping according to claim 1 or 2, wherein the degree of deterioration is as follows.

4. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure the reference dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A device for measuring the degree of deterioration of molding powder, which is subject to inspection, based on the above.

5. The device for measuring the degree of deterioration of a molding powder according to claim 4, wherein the molding powder is a thermoplastic resin or a metal.

6. The Hansen solubility parameter of the aforementioned solvent is 14 (J / cm²). ３ ) １／２ More than 30 (J / cm ３ ) １／２ The following is the device for measuring the degree of deterioration of molding powder according to claim 4 or 5.

7. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure the reference dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A measurement step for calculating the degree of deterioration of the moldable powder after use based on the above, Based on the degree of deterioration of the used molding powder, a production step is performed to mix the used molding powder with the unused molding powder to produce recycled molding powder. A method for producing recycled powder for molding.

8. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure the reference dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A measuring unit that calculates the degree of deterioration of the moldable powder after use based on the above, Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder. A manufacturing apparatus for recycled powder used in molding, equipped with the following features.

9. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure the reference dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A measurement step for calculating the degree of deterioration of the moldable powder after use based on the above, Based on the degree of deterioration of the used molding powder, a production step is made to mix the used molding powder with the unused molding powder to produce recycled molding powder. A molding process in which a three-dimensional object is formed by additive manufacturing using the aforementioned recycled powder for molding, A method for manufacturing a three-dimensional object having the properties of a three-dimensional molded object.

10. Using a pulsed NMR apparatus, a reference dispersion is obtained by dispersing a reference molding powder in a solvent. １ H nucleus spin-spin relaxation time T2 １ The measurement is taken, and the inspection dispersion obtained by dispersing the used molding powder to be inspected in the solvent is also measured. １ H nucleus spin-spin relaxation time T2 ２ Measure the reference dispersion １ H nucleus spin-spin relaxation time T2 １ and the inspection dispersion １ H nucleus spin-spin relaxation time T2 ２ A measuring unit that calculates the degree of deterioration of the moldable powder after use based on the above, Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder, A molding unit that forms a three-dimensional object by additive manufacturing using the aforementioned recycled powder for molding, A manufacturing apparatus for three-dimensional objects equipped with the following features.

11. Using a pulsed NMR device, a dispersion of molding powder in a solvent １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A device for measuring the degree of deterioration of a molding powder, which calculates the specific surface area of ​​the molding powder based on the spin-spin relaxation time T2 of the H nucleus and calculates the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder.

12. Using a pulsed NMR device, a dispersion of molding powder in a solvent １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A method for measuring the degree of deterioration of a molding powder, comprising calculating the specific surface area of ​​the molding powder based on the spin-spin relaxation time T2 of the H nucleus, and calculating the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder.

13. The method for measuring the degree of deterioration of a molding powder according to claim 12, wherein the molding powder is a thermoplastic resin or a metal.

14. The Hansen solubility parameter of the aforementioned solvent is 14 (J / cm²). ３ ) １／２ More than 30 (J / cm ３ ) １／２ The method for measuring the degree of deterioration of molding powder according to claim 12 or 13, which is as follows:

15. The solvent １ A method for measuring the degree of deterioration of a molding powder according to claim 12 or 13, wherein the spin-spin relaxation time T2 of the H nucleus is 1000 ms or more.

16. A method for measuring the degree of deterioration of a molding powder according to claim 12 or 13, wherein the degree of deterioration of the molding powder after use is calculated based on the specific surface area of ​​the molding powder before use, which has been measured and calculated in advance.

17. After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A measurement step which involves calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and calculating the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder, Based on the degree of deterioration of the used molding powder, a production step is performed to mix the used molding powder with the unused molding powder to produce recycled molding powder. A method for producing recycled powder for molding.

18. After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A measuring unit calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and calculates the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder. Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder. A manufacturing apparatus for recycled powder used in molding, equipped with the following features.

19. After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A measurement step which involves calculating the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and calculating the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder, Based on the degree of deterioration of the used molding powder, a production step is performed to mix the used molding powder with the unused molding powder to produce recycled molding powder. A molding process in which a three-dimensional object is formed by additive manufacturing using the aforementioned recycled powder for molding, A method for manufacturing a three-dimensional object having the properties of a three-dimensional molded object.

20. After use, the 3D printing powder is sampled, and a pulsed NMR spectrometer is used to analyze the dispersion obtained by dispersing the used 3D printing powder in a solvent. １ The spin-spin relaxation time T2 of the H nucleus is measured, and the dispersion １ The spin-spin relaxation time T2 of the H nucleus and the solvent １ A measuring unit calculates the specific surface area of ​​the used molding powder based on the spin-spin relaxation time T2 of the H nucleus, and calculates the degree of deterioration of the molding powder based on a comparison with the specific surface area of ​​a reference molding powder. Based on the degree of deterioration of the used molding powder, a generating unit mixes the used molding powder with the unused molding powder to generate recycled molding powder, A molding unit that forms a three-dimensional object by additive manufacturing using the aforementioned recycled powder for molding, A manufacturing apparatus for three-dimensional objects equipped with the following features.

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