Resin powder, three-dimensional molded body, and method for manufacturing a three-dimensional molded body

Abstract

To provide a reusable resin powder in the powder bed fusion bonding method. [Solution] A resin powder containing a propylene polymer powder and satisfying the following (a-1) and (b). (a-1) The heat of fusion (ΔH) calculated by differential scanning calorimetry (DSC) in accordance with ISO 3146 is 70 J / g or more and less than 125 J / g. (b) 23℃ n-decane soluble portion (D sol ) is the amount of n-decane soluble at 23°C (D sol ) and the insoluble portion of n-decane at 23°C (D insol It is 6.0% to 15.0% by mass relative to the total mass of ( ).

Description

[Technical Field]

[0001] This disclosure relates to resin powder, a three-dimensional molded article, and a method for manufacturing a three-dimensional molded article. [Background technology]

[0002] Representative examples of 3D printing methods using thermoplastic resins include material extrusion (MEX) and powder bed fusion (PBF) using powder materials. Powder bed fusion offers high molding accuracy and the ability to produce fine objects, and various methods have been proposed for this method.

[0003] Patent Document 1 discloses a powder material used in the powder bed fusion bonding method, which is a "resin powder containing a polyolefin resin, having a melting point of 150°C or higher, a melt mass flow rate (MFR) measured in accordance with JIS K 7210 of 0.35 (g / 10min) or more and 8.50 (g / 10min) or less, and a particle size distribution (volume average particle size Dv / number average particle size Dn) of 1.35 or less." [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-146679 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, from the perspective of cost and environmental impact, the reuse of powder materials has become necessary in powder bed fusion fusion.

[0006] In powder bed fusion molding, it is necessary to recoat the material powder at a temperature close to its melting point. At high temperatures close to the melting point of the powder, powders containing block polypropylene with rubber components in the resin are prone to agglomeration. When powder agglomeration occurs, the reuse rate of the powder after molding decreases. On the other hand, the rubber component is important from the standpoint of ensuring the impact resistance of the molded object (three-dimensional molded body).

[0007] One embodiment of this disclosure aims to provide a reusable resin powder in a powder bed fusion bonding method. [Means for solving the problem]

[0008] The means for solving the above problems include the following embodiments. <1> A resin powder containing a propylene polymer powder and satisfying the following conditions (a-1) and (b). (a-1) The heat of fusion (ΔH) calculated by differential scanning calorimetry (DSC) in accordance with ISO 3146 is 70 J / g or more and less than 125 J / g. (b) 23℃ n-decane soluble portion (D sol ) is the amount of n-decane soluble at 23°C (D sol ) and the insoluble portion of n-decane at 23°C (D insol It is 6.0% to 15.0% by mass relative to the total mass of ( ). <2> The following (a-2) is also satisfied: <1> The resin powder described above. (a-2) Melting point (T) measured by differential scanning calorimetry (DSC) in accordance with ISO 3146 standard m The temperature is between 150°C and 170°C. <3> The following (c-1) is also satisfied: <1> or <2> The resin powder described above. (c-1) When the first three-dimensional molded body is formed by powder bed fusion bonding, the Charpy impact strength (with notch) of the first three-dimensional molded body, measured according to ISO 179-1 standard, is 2.0 kJ / m at 23°C. 2 That's all. <4> The resin powder according to any one of <1> to <3>, further satisfying the following (c-2). (c-2) When the surplus of the resin powder is reused as the next three-dimensional molded body by the powder bed fusion bonding method, the change rate of the Charpy impact strength (with notch) measured according to ISO 179-1 standard between the first three-dimensional molded body and the next three-dimensional molded body ([(Charpy impact strength (with notch) of the next three-dimensional molded body - Charpy impact strength (with notch) of the first three-dimensional molded body) / Charpy impact strength (with notch) of the first three-dimensional molded body]×100) is 10% or less. <5> The resin powder according to any one of <1> to <4>, which is used for three-dimensional molding. <6> A three-dimensional molded body molded using the resin powder according to any one of <1> to <5>. <7> A method for manufacturing a three-dimensional molded body, in which a three-dimensional molded body is manufactured by the powder bed fusion bonding method using the resin powder according to any one of <1> to <5>.

Advantages of the Invention

[0009] According to one embodiment of the present disclosure, in the powder bed fusion bonding method, a resin powder, a three-dimensional molded body, and a method for manufacturing a three-dimensional molded body that can be reused are provided.

Modes for Carrying Out the Invention

[0010] In the present disclosure, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical ranges described in other stepwise descriptions. In the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. [[ID=E26]]In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved.

[0011] In this disclosure, the term "rubber component" refers to a component soluble in n-decane at 23°C, and "soluble" means a component that dissolves at a rate of 0.1 mg or more in 100 ml of n-decane at 23°C.

[0012] In this disclosure, the term "first three-dimensional molded body" refers to the first three-dimensional molded body produced by powder bed fusion bonding.

[0013] In this disclosure, the term "next three-dimensional molded body" refers to a three-dimensional molded body obtained by reusing the surplus resin powder from the first three-dimensional molded body produced by powder bed fusion bonding.

[0014] <Resin powder> The resin powder of this disclosure is a resin powder that contains a propylene polymer powder and satisfies the following (a-1) and (b). (a-1) The heat of fusion (ΔH) calculated by differential scanning calorimetry (DSC) in accordance with ISO 3146 is 70 J / g or more and less than 125 J / g. (b) 23℃ n-decane soluble portion (D sol ) is the amount of n-decane soluble at 23°C (D sol ) and the insoluble portion of n-decane at 23°C (D insol It is 6.0% to 15.0% by mass relative to the total mass of ( ).

[0015] As described above, the resin powder of this disclosure suppresses powder aggregation by controlling the particle crystallinity and rubber component content within a certain range, and a three-dimensional molded body formed by powder bed fusion using this powder can maintain its mechanical properties even when using recycled powder after molding. Therefore, the resin powder of this disclosure can be reused in powder bed fusion.

[0016] -Resin powder- The resin powder of this disclosure includes propylene polymer powder. Examples of propylene polymers include propylene homopolymers, propylene random copolymers containing constituent units derived from propylene and constituent units derived from olefin monomers other than propylene, and propylene block copolymers. The propylene polymer powder may also be obtained from biomass-derived raw materials.

[0017] From the viewpoint of obtaining a three-dimensional molded article with excellent impact strength, the propylene-based polymer is preferably a propylene-based block copolymer.

[0018] Propylene-based block copolymers have a propylene-derived skeleton as an essential skeleton, and are composed of skeletons derived from ethylene and one or more olefins selected from α-olefins having 4 to 20 carbon atoms. Examples of α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene.

[0019] When the propylene copolymer is a propylene-based block copolymer, the propylene-based block copolymer contains constituent units derived from ethylene and one or more olefins selected from α-olefins having 4 to 20 carbon atoms, and the total content of olefins other than propylene may be 4 mol% to 30 mol% relative to the propylene-based block copolymer.

[0020] The propylene polymer may have either an isotactic or syndiotactic stereoregularity in the portion where the propylene-derived structural units are repeatedly bonded. However, from the viewpoint of obtaining a three-dimensional molded article with excellent impact strength, an isotactic structure is preferred.

[0021] The heat of fusion (ΔH) calculated by differential scanning calorimetry (DSC) according to ISO 3146 standard of the resin powder of the present disclosure is 70 J / g or more and less than 125 J / g. Since the heat of fusion (ΔH) is 70 J / g or more and less than 125 J / g, it can be evaluated that it has an appropriate degree of crystallinity to maintain the impact resistance of the three-dimensional molded body while suppressing the aggregation of the resin powder.

[0022] When the heat of fusion (ΔH) is less than 70 J / g, the degree of crystallinity of the resin powder is small, the cohesiveness of the resin powder increases, and the filling property of the three-dimensional molded body decreases in the recoating process of the manufacturing method of the three-dimensional molded body by the powder bed fusion method. Therefore, with use, the impact strength of the three-dimensional molded body decreases, so the resin powder is not suitable for reuse. On the other hand, when the heat of fusion (ΔH) is 125 J / g or more, the degree of crystallinity of the resin powder is large, and the impact strength of the three-dimensional molded body decreases and becomes brittle with use, so the resin powder is not suitable for reuse.

[0023] From the viewpoints of suppressing the aggregation of the resin powder and maintaining the strength of the three-dimensional molded body, the heat of fusion (ΔH) is preferably 70 J / g or more and less than 125 J / g, more preferably 70 J / g or more and less than 120 J / g, and even more preferably 70 J / g or more and less than 115 J / g. The heat of fusion (ΔH) is a value calculated by the method described in the examples.

[0024] As a method for adjusting the heat of fusion (ΔH) in the resin powder, it can be adjusted to a desired heat of fusion (ΔH) by adjusting the ratio of the gas composition (ethylene and propylene) during the polymerization of the resin powder.

[0025] The melting point (T m ) measured by differential scanning calorimetry (DSC) according to ISO 3146 standard of the resin powder is preferably 150°C to 170°C, more preferably 158°C to 170°C, and even more preferably 165°C to 170°C from the viewpoint of the heat resistance of the resin powder. The melting point (T m ) is a value measured by the method described in the examples.

[0026] In resin powder, the above melting point (T m As a method to adjust the melting point (T), the ratio of gas composition (ethylene, propylene) during resin powder polymerization can be adjusted to obtain the desired melting point (T m It can be adjusted to ).

[0027] The resin powder of this disclosure (preferably including a propylene-based block copolymer powder) has a portion that is soluble at 23°C n-decane and a portion that is insoluble at 23°C n-decane. The "23°C n-decane soluble portion" refers to the portion of the resin powder that is dissolved in the n-decane solution after being heated and dissolved in n-decane at 145°C for 30 minutes and then cooled to 23°C, as described in the examples below.

[0028] The 23°C n-decane soluble portion preferably contains a copolymer (rubber component) as its main component, consisting of propylene and one or more olefins selected from ethylene and α-olefins having 4 to 20 carbon atoms. In this case, the olefin content other than propylene in the 23°C n-decane soluble portion (total content of ethylene and one or more olefins selected from α-olefins having 4 to 20 carbon atoms) may be 4 mol% to 30 mol% relative to the 23°C n-decane soluble portion. "Contained as a main component" means that the ratio of the copolymer to the n-decane soluble portion is 50% by mass or more.

[0029] The 23°C n-decane soluble portion (D) of the resin powder disclosed herein sol ) is the soluble portion (D) of n-decane at 23℃. sol ) and the insoluble portion of n-decane at 23°C (D insol The amount is 6.0% to 15.0% by mass relative to the total mass of (D). 23℃ n-decane soluble portion (D sol By keeping the above range, it is possible to suppress the aggregation of resin powder while maintaining the impact resistance of the three-dimensional molded body.

[0030] D sol If the ratio is lower than 6.0 mass%, the impact strength of the three-dimensional molded body decreases, which is undesirable. D solWhen the ratio exceeds 15.0% by mass, the cohesiveness of the resin powder increases, and in the recoating step of the powder bed fusion bonding method for manufacturing three-dimensional molded bodies, the filling properties of the molded body decrease. As a result, the impact strength of the molded body changes significantly with use, and consequently the impact strength decreases, making the resin powder unsuitable for reuse.

[0031] D sol The ratio is preferably 7.0% to 15.0% by mass, and more preferably 8.0% to 13.0% by mass, from the viewpoint of suppressing aggregation of resin powder and maintaining the strength of the three-dimensional molded article.

[0032] In resin powder, the amount of 23°C n-decane soluble can be adjusted by adjusting the ratio of the gas composition (ethylene and propylene) during resin powder polymerization to achieve the desired amount of 23°C n-decane soluble.

[0033] The intrinsic viscosity [η] of the n-decane soluble portion at 23°C may be between 1.0 dl / g and 10 dl / g.

[0034] The weight-average molecular weight of the n-decane insoluble portion at 23°C is not particularly limited. The weight-average molecular weight can be calculated from the molecular weight distribution converted to polypropylene (PP) using gel permeation chromatography (GPC). The molecular weight distribution (weight-average molecular weight: Mw / number-average molecular weight: Mn) may be between 1.0 and 10.

[0035] The volume-average particle size of the resin powder is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, even more preferably 25 μm to 100 μm, and particularly preferably 35 μm to 70 μm, from the viewpoint of ensuring good fluidity and filling properties of the resin powder in the recoating step of the powder bed fusion bonding method for manufacturing three-dimensional molded articles, and contributing to three-dimensional molding by powder bed fusion bonding.

[0036] The volume-average particle size of resin powder can be adjusted, for example, by performing grinding treatments such as mechanical grinding or wet grinding, particle spheroidization, and classification on particles whose particle size has been controlled by polymerization or on prepared resin powder particles.

[0037] The particle size is measured using a particle size distribution analyzer (for example, the MT3300EXII manufactured by Microtrac-Bell Corporation), employing the refractive index of each powder particle, and measured using a dry (air) method without the use of solvents. Details will be explained in the examples.

[0038] In the recoating step of the powder bed fusion bonding method for manufacturing three-dimensional molded articles, the shape of the resin powder particles is preferably spherical, as this ensures good filling of the powder layer and contributes to three-dimensional molding by the powder bed fusion bonding method.

[0039] The MFR (melt flow rate) of the resin powder, measured at 230°C and a 2.16 kg load in accordance with ASTM D1238, is not particularly limited, but is preferably between 0.1 g / 10 min and 20 g / 10 min. If the MFR of the resin powder is lower than 0.1 g / 10 min, the weldability between resins may decrease. If the MFR of the resin powder exceeds 20 g / 10 min, the impact strength of the resulting three-dimensional molded article may decrease with use.

[0040] The Charpy impact strength (with notch) of the resin powder of this disclosure, when used to form the first three-dimensional molded body by powder bed fusion bonding, as measured according to ISO 179-1, is 2.0 kJ / m². 2 Preferably, it is 2.2 kJ / m³ 2 It is more preferable that the value be greater than or equal to 2.4 kJ / m³. 2 It is even more preferable that the above is true. The Charpy impact strength (with notch) is 2.0 kJ / m 2 As a result of meeting these requirements, the three-dimensional molded body has superior strength.

[0041] The Charpy impact strength (with notch) of the first three-dimensional molded body is 100 kJ / m 2Preferably, it is 95 kJ / m 2 It is more preferable that the following is true: 90 kJ / m 2 The following is even more preferable: The method for measuring Charpy impact strength (with notch) according to ISO 179-1 is detailed in the examples.

[0042] The Charpy impact strength (with notches), measured according to ISO 179-1, is 2.0 kJ / m² when the surplus resin powder from the first three-dimensional molded body is reused to form the next three-dimensional molded body using the powder bed fusion method. 2 Preferably, it is 2.2 kJ / m³ 2 It is more preferable that the value be greater than or equal to 2.4 kJ / m³. 2 It is even more preferable that the above is true. The Charpy impact strength (with notch) is 2.0 kJ / m 2 As a result of meeting these requirements, the three-dimensional molded body has superior strength.

[0043] The Charpy impact strength (with notch) of the following three-dimensional molded body is 100 kJ / m 2 Preferably, it is 95 kJ / m 2 It is more preferable that the following is true: 90 kJ / m 2 The following is even more preferable:

[0044] The rate of change in the Charpy impact strength (notched) between the first and subsequent three-dimensional molded bodies, as measured according to ISO 179-1 ([(Charpy impact strength (notched) of the first three-dimensional molded body - Charpy impact strength (notched) of the subsequent three-dimensional molded body) / Charpy impact strength (notched) of the first three-dimensional molded body)] × 100), is preferably 10% or less, more preferably 4% or less, even more preferably 3% or less, and particularly preferably 2% or less. Since the rate of change is 10% or less, the three-dimensional molded bodies maintain their mechanical properties, and the resin powder of this disclosure can be reused in the powder bed fusion method.

[0045] -Other ingredients- The resin powder of this disclosure may also contain other components besides the resin powder containing the propylene polymer powder, to the extent that it does not impair the effects of the invention. Examples of other components include resin components such as thermoplastic resins other than propylene polymers, elastomer components (for example, propylene-based elastomers such as polyisobutylene, butyl rubber, propylene-ethylene copolymer rubber, propylene-butene copolymer rubber, and propylene-butene-ethylene copolymer rubber, and ethylene-based elastomers such as ethylene-propylene copolymer rubber), thermosetting resins, additive components, and the like. Biomass-derived raw materials may be added to the resin powder.

[0046] Examples of additive components include heat stabilizers, antistatic agents, weather stabilizers, light stabilizers, UV absorbers, anti-aging agents, antioxidants, neutralizing agents, fatty acid metal salts, softeners, dispersants, colorants, lubricants, pigments, dyes, fillers, whitening agents, antistatic agents, solvents, wetting agents, antimicrobial agents, chelating agents, flow aids, reinforcing agents, energy absorption enhancers, energy absorption inhibitors, laser absorbers, fusion agents, and finish enhancers. The aforementioned other components may be used individually or in combination of two or more. When mixing the other components to produce resin powder, the mixing order is arbitrary; they may be mixed simultaneously, or a multi-stage mixing method may be employed, such as mixing some components before mixing others.

[0047] The resin powder of this disclosure may contain a flow aid. Preferably, the flow aid is dry-blended with the resin powder. In this disclosure, a flow aid refers to a substance that suppresses the aggregation of resin powder due to the adhesive force between the resin powder particles. By including a flow aid, the fluidity of the resin powder can be improved, and the filling of the resin powder becomes more uniform when forming a three-dimensional molded body. As a result, the resulting three-dimensional molded body tends to have less warping.

[0048] Examples of fluidizing agents include silica (silicon dioxide) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide), alumina colloid (alumina sol), and alumina white; calcium carbonate such as light calcium carbonate, heavy calcium carbonate, finely powdered calcium carbonate, and special calcium carbonate-based fillers; clay (aluminum silicate powder) such as nepheline syenite fine powder, calcined clay such as montmorillonite and bentonite, and silane-modified clay; silica-containing compounds such as talc, diatomaceous earth, and silica sand; crushed natural minerals such as pumice powder, pumice balloons, slate powder, and mica powder; and sulfur Examples include minerals such as barium acid, lithopone, calcium sulfate, molybdenum disulfide, and graphite; glass-based fillers such as glass fibers, glass beads, glass flakes, and foamed glass beads; fly ash spheres, volcanic glass hollow bodies, synthetic inorganic hollow bodies, single-crystal potassium titanate, carbon fibers, carbon nanotubes, carbon hollow spheres, fullerenes, anthracite powder, artificial cryolite, titanium dioxide, magnesium oxide, basic magnesium carbonate, dolomite, potassium titanate, calcium sulfite, mica, asbestos, calcium silicate, molybdenum sulfide, boron fibers, and silicon carbide fibers. Among these, silica, alumina, calcium carbonate, glass-based fillers, and titanium dioxide are preferred, with silica being more preferred. Commercially available silica products include the "AEROSIL" (registered trademark) series of fumed silica manufactured by Nippon Aerosil Co., Ltd., the "Rheoroseal" (registered trademark) series of dry silica manufactured by Tokuyama Corporation, and the X-24 series of sol-gel silica powder manufactured by Shin-Etsu Chemical Co., Ltd.

[0049] The resin powder of this disclosure may contain a reinforcing material. Examples of reinforcing materials include inorganic reinforcing materials composed of inorganic compounds and organic reinforcing materials composed of organic compounds. The inorganic reinforcing material may be dry-blended with the resin powder or may be contained within the resin powder. In terms of controlling the spherical shape of the resin powder and improving fluidity, it is preferable that the inorganic reinforcing material is dry-blended with the resin powder. The reinforcing material may also serve as the aforementioned flow aid.

[0050] Reinforcement materials include, for example, glass-based fillers such as glass fibers, glass beads, glass flakes, and foamed glass beads; clays such as nepheline syenite fine powder, calcined clay such as montmorillonite and bentonite, and silane-modified clay (aluminum silicate powder); silica-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; silica (silicon dioxide) such as fused silica, crystalline silica, and amorphous silica; alumina (aluminum oxide), alumina colloid (alumina sol), and alumina white; light calcium carbonate, heavy calcium carbonate, and fine powders. Examples include calcium carbonate, special calcium carbonate-based fillers, fly ash spheres, volcanic glass hollow bodies, synthetic inorganic hollow bodies, single-crystal potassium titanate, potassium titanate fibers, carbon fibers, carbon nanotubes, carbon hollow spheres, fullerenes, anthracite powder, cellulose nanofibers, artificial cryolite, titanium dioxide, magnesium oxide, basic magnesium carbonate, dolomite, calcium sulfite, mica, asbestos, calcium silicate, molybdenum sulfide, boron fibers, silicon carbide fibers, polypropylene fibers, polyamide fibers, polyoxymethylene fibers, ultra-high molecular weight polyethylene fibers, polytetrafluoroethylene fibers, liquid crystal (LCP) fibers, and Kevlar registered trademark fibers. Among these, glass-based fillers, minerals, and carbon fibers are preferred due to their hardness and significant strength-enhancing effect.

[0051] Surface-treated reinforcing materials (especially inorganic reinforcing materials) may be used. This makes it possible to improve the adhesion between the reinforcing material and the resin powder. Examples of surface treatment agents used for surface treatment include silane coupling agents such as aminosilane, epoxysilane, and acrylicsilane. These surface treatment agents may be immobilized on the surface of the inorganic reinforcing material by a coupling reaction, or they may coat the surface of the inorganic reinforcing material. When recycling the powder used in three-dimensional molding, it is preferable to use a material immobilized by a coupling reaction, as it is less likely to be modified by heat or other factors.

[0052] The resin powder of this disclosure may contain an energy absorption enhancer. The energy absorption enhancer is a substance that absorbs electromagnetic radiation. The energy absorption enhancer may also function as a flow aid or reinforcing agent.

[0053] Examples of energy absorption enhancers include pigments, carbon black, carbon fibers, copper hydroxyphosphate, near-infrared absorbing dyes, near-infrared absorbing pigments, metal nanoparticles, polythiophene, poly(p-phenylene sulfide), polyaniline, poly(pyrrole), polyacetylene, poly(p-phenylene vinylene), polyparaphenylene, poly(styrene sulfonate), poly(3,4-ethylenedioxythiophene)-poly(styrenephosphonate)p-diethylaminobenzaldehyde diphenylhydrazone, anti-9-isopropylcarbazole-3-, or conjugated polymers consisting of combinations thereof.

[0054] The resin powder of this disclosure may contain an energy absorption inhibitor. The energy absorption inhibitor is a substance that does not readily absorb electromagnetic radiation. The energy absorption inhibitor may also function as a flow aid or reinforcing agent.

[0055] Examples of energy absorption inhibitors include materials that reflect particulate electromagnetic radiation such as titanium, heat-insulating powders such as mica powder and ceramic powder, and water. Either an energy absorption enhancer or an energy absorption inhibitor may be used, or both may be used in combination to adjust the degree of absorption of electromagnetic radiation.

[0056] The resin powder of this disclosure may contain a fusing agent. The fusing agent may be, for example, a dispersion containing a radiation absorber (e.g., an active material). The active material may be any infrared light absorbing colorant. The solvent of the fusing agent may be water or a non-aqueous solvent (e.g., ethanol, acetone, n-methylpyrrolidone, aliphatic hydrocarbon, etc.). For example, the fusing agent may be a mixture of the active material and the solvent (preferably a mixture that does not contain other components). The fusion agent may, for example, include at least one cosolvent; at least one surfactant; at least one anticoagulation agent; at least one chelating agent; at least one buffer; at least one biocide; and water.

[0057] The resin powder of this disclosure may contain a finish enhancer. The finish enhancer may contain a surfactant, a cosolvent, and a balanced amount of water. The finish enhancer may be a mixture consisting of a surfactant, a cosolvent, and a balanced amount of water, and not containing other components. The finish enhancer may contain a colorant, or it may be a mixture consisting of a colorant, a surfactant, a cosolvent, and a balanced amount of water, and not containing other components. The finish enhancer may contain one or more components such as an anticoagulant, an antimicrobial agent, or a chelating agent. The resin powder and propylene polymer powder of this disclosure may be coated with any surface-active coating. Examples of surface-active coatings include coatings containing surfactants, acidic polymers, salts of acidic polymers, inorganic particles, etc., and the coating may use one of these or two or more of these.

[0058] Examples of surfactants used in surface-active coatings include anionic surfactants, nonionic surfactants, and cationic surfactants. Examples of anionic surfactants include sodium lauryl sulfate and linear or branched alkylbenzene sulfonates.

[0059] The surface-active coating may be an inorganic granular coating using inorganic particles, for example, an inorganic granular coating using fumed metal oxide nanoparticles. Examples of inorganic particles used in the inorganic granular coating include silicon dioxide, e.g., AEROSIL® 200, aluminum oxide, e.g., AEROXIDE® AluC and its aqueous dispersions, e.g., AERODISP® W1824, AERODISP® W440, etc.

[0060] Surface-active coatings are applied using appropriate methods. Examples include spray coating, pan coating, air or gas suspension coating, liquid phase coating, liquid dispersion coating, and immersion. Reactions such as polymerization may also be carried out after coating.

[0061] If the resin powder of this disclosure contains other components, the proportion of the propylene polymer to the total resin powder may be 80% by mass or more and less than 100% by mass, or 90% by mass or more and less than 100% by mass.

[0062] -Method for manufacturing resin powder- The method for producing the resin powder is not particularly limited. For example, propylene polymer powder can be produced by referring to the catalysts, production methods, etc., described in paragraphs 0022 to 0082 of International Publication No. 2012 / 102050.

[0063] The resin powder of this disclosure can also be manufactured by referring to catalysts, manufacturing methods, etc., described in, for example, International Publication No. 2009 / 011231, Japanese Patent Publication No. 2011-57789, Japanese Patent Publication No. 2019-206616, International Publication No. 2012 / 102050, etc.

[0064] -Applications- The resin powder of this disclosure can be used for the three-dimensional molding of three-dimensional molded articles. In particular, it is suitable for the three-dimensional molding of three-dimensional molded articles by powder bed fusion bonding.

[0065] The three-dimensional molded articles that can be molded using the resin powder of this disclosure are not particularly limited and include, but are, automotive molded articles (e.g., console parts, switch parts, door trim parts, instrument panel parts, clips, covers, etc.), electrical appliance molded articles (electrical appliance parts, housings, etc.), furniture components, building components, construction materials, aircraft components, toys, shoes, sporting goods, decorative items, cases, etc.

[0066] <Three-dimensional molded object> The three-dimensional molded articles of this disclosure are molded using the aforementioned resin powder. Examples of three-dimensional molded articles include the aforementioned automotive molded articles and other molded articles. The three-dimensional molded articles of this disclosure may be sintered or molten bodies of the aforementioned resin powder.

[0067] The three-dimensional molded body of this disclosure can be manufactured by three-dimensional molding using the aforementioned resin powder by powder bed fusion bonding.

[0068] <Method for manufacturing a three-dimensional molded body> The method for manufacturing a three-dimensional molded article according to this disclosure is a method for manufacturing a three-dimensional molded article by powder bed fusion bonding using the resin powder described above. Aside from using the resin powder described above, the three-dimensional molded article can be manufactured by the same method as the conventional powder bed fusion bonding method.

[0069] For example, the method for manufacturing a three-dimensional molded article according to the present disclosure may include: step 1 (recoating step) of laying the resin powder in layers to form a thin layer of the resin powder; step 2 (welding step) of selectively irradiating the preheated thin layer with laser light to form a welded layer in which the resin powder is fused together; and step 3 (three-dimensional molding step) of repeating steps 1 and 2 in this order to create a three-dimensional molded article in which welded layers are stacked.

[0070] A single welded layer constituting the three-dimensional molded body is formed by going through steps 1 and 2, and by repeating steps 1 and 2, the welded layers are sequentially stacked to form the three-dimensional molded body. From the viewpoint of achieving high-precision molding (three-dimensional molding), the method for manufacturing a three-dimensional molded body according to this disclosure preferably includes step 4, in which a thin layer of resin powder is preheated before irradiating with a laser in step 2. The preheating temperature is preferably around the melting point of the resin powder -10°C to 15°C. The method for manufacturing a three-dimensional molded body according to this disclosure may include a step in which, after molding the first three-dimensional molded body, the excess resin powder is separated and recovered, and the resulting resin powder is reused to mold the next three-dimensional molded body.

[0071] Each of the aforementioned steps may be carried out with reference to, for example, the method for manufacturing a three-dimensional molded body described in International Publication No. 2020 / 213586, HP Multi Jet Fusion technology, or 3D printing using the molding material described in Japanese Patent No. 7071532. [Examples]

[0072] The embodiments of this disclosure will be described in detail below with reference to examples. The embodiments of this disclosure are not limited to the following examples. The physical properties of the resin powders in the examples were measured by the following methods.

[0073] (1) Volume-average particle size The volume-average particle size of the resin powder was measured using a particle size distribution analyzer (Microtrac-Bell Co., Ltd., MT3300EXII), employing the refractive index of each powder particle, and using a dry (air) method without solvent. The refractive index was set to 1.5. A sample was used in which 0.1 g of powder particles were mixed with 0.2 g of surfactant (Kao Corporation, Emal E-27C) and 30 mL of water, and ultrasonically dispersed for 10 minutes.

[0074] (2) MFR The melt flow rate (MFR) of the resin powder was measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg.

[0075] (3) 23℃ n-decane soluble portion 5 g of resin powder sample was mixed with 200 mL of n-decane and heated at 145°C for 30 minutes until dissolved. The mixture was cooled to 20°C over approximately 3 hours and left at room temperature for 30 minutes. The precipitate (α) was then filtered off. The filtrate was placed in approximately three times its volume of acetone to precipitate the components dissolved in the n-decane. Precipitate (β) (hereinafter, n-decane soluble portion: D) sol The filtrate, n-decane, and acetone were filtered off, and the precipitate was dried. No residue was observed even after concentrating and drying the filtrate. The precipitate (α) was added again to 200 mL of n-decane, heated at 145°C for 30 minutes, the solution was filtered, and the inorganic filler was filtered off. The filtrate was cooled to 20°C over approximately 3 hours, left at room temperature for 30 minutes, and then precipitate (γ) (hereinafter referred to as the n-decane-insoluble portion of the resin powder: D) was removed. insol ) was filtered out. In the separation of n-decane from resin powder, the precipitate (γ) is the n-decane-insoluble portion (D insol Since this corresponds to ), the amount of n-decane soluble was calculated as follows. Amount of n-decane soluble portion (mass%) = [Precipitate (β) amount / (Precipitate (γ) amount + Precipitate (β))] × 100

[0076] (4) Melting point (T m ) · Heat of fusion (ΔH) In accordance with the measurement method of ISO 3146 (Method for determining the transition temperature of plastics, JIS K7121), a differential scanning calorimetry device (Diamond DSC, manufactured by PerkinElmer) was used to heat the resin powder to 230°C at a rate of 10°C / min, and the endothermic peak temperature was measured at the melting point (T) of the resin powder. m The heat of fusion (ΔH) was calculated by setting the temperature 30°C higher than the temperature at which the endothermic peak disappears during melting point measurement, and then cooling at 10°C / min, from the area of ​​the exothermic peak.

[0077] (5) Charpy impact strength and rate of change of Charpy impact strength A three-dimensional molded body was fabricated using resin powder in the following manner. First, using a 3D 3D printer (SINTERSTATION 2500 plus, manufactured by 3D SYSTEMS), the prepared resin powder was spread onto the printing stage at a predetermined recoating speed (160 mm / s) at a printing temperature of 150°C, forming a thin layer with a thickness of 0.1 mm. On this thin layer, a CO2 laser equipped with a CO2 laser wavelength galvanometer scanner was irradiated with laser light in a range of 360 mm (X) x 310 mm (Y) under the following conditions, creating a welded layer of 10 mm (width) x 80 mm (length) in the XY plane, with the longitudinal direction of the test piece being the X direction. Subsequently, the resin powder was spread again as a thin layer with a thickness of 0.1 mm on top of the welded layer, and laser light was irradiated to build up the welded layer. These processes were repeated to create a three-dimensional molded body (a laminate of welded layers). The resin powder containing the three-dimensional molded body obtained by the above molding process was extracted, and the three-dimensional molded body and resin powder were separated using a powder separation device (3D SYSTEMS (MQC 600 single)).

[0078] -Laser light emission conditions- Laser output: 40W Laser light wavelength: 10.6 μm Beam diameter: 500 μm on thin-layer surfaces Number of lines: 1 line

[0079] The resulting molded body was subjected to a Charpy impact strength test (with notch) (kJ / m²) in accordance with ISO 179-1 under the following conditions. 2 ) was measured. -Measurement conditions- Temperature: 23℃ Test specimen: 10mm (width) x 80mm (length) x 4mm (thickness)

[0080] Furthermore, the resin powder obtained through separation was reused, and a three-dimensional molded body was created under the same conditions. The resulting test specimens were subjected to the following Charpy impact strength test (with notch) (kJ / m²). 2 The Charpy impact strength of the following three-dimensional molded body was measured and used as the Charpy impact strength. -Measurement conditions- Temperature: 23℃ Test specimen: 10mm (width) x 80mm (length) x 4mm (thickness)

[0081] The rate of change in Charpy impact strength (with notch) was calculated using the following formula based on the obtained measurement results. Charpy impact strength (with notch) change rate (%) = [(Charpy impact strength of the first molded object (with notch) - Charpy impact strength of the next molded object (with notch)) / Charpy impact strength of the first molded object (with notch)] × 100

[0082] [Example 1] A prepolymerization catalyst was prepared as follows, and a resin powder containing a propylene-based polymer powder was prepared using the prepolymerization catalyst. (1) Preparation of solid titanium catalyst components 952 g of anhydrous magnesium chloride, 4420 mL of decane, and 3906 g of 2-ethylhexyl alcohol were heated at 130°C for 2 hours to obtain a homogeneous solution. 213 g of phthalic anhydride was added to this solution, and the mixture was stirred at 130°C for a further 1 hour to dissolve the phthalic anhydride. The homogeneous solution obtained in this manner was cooled to 23°C, and 750 mL of this homogeneous solution was added dropwise over 1 hour to 2000 mL of titanium tetrachloride maintained at -20°C. After the dropwise addition, the temperature of the resulting mixture was raised to 110°C over 4 hours. At 110°C, 52.2 g of diisobutyl phthalate (DIBP) was added, and the mixture was maintained at the same temperature for 2 hours with stirring. The solid portion was then collected by hot filtration, and this solid portion was resuspended in 2750 mL of titanium tetrachloride, and then heated again at 110°C for 2 hours. After heating, the solid portion was again collected by hot filtration and washed with decane and hexane at 110°C until no titanium compounds were detected in the washing solution. The solid titanium catalyst component prepared as described above was stored as a hexane slurry, and a portion of it was dried to examine the catalyst composition. The solid titanium catalyst component contained 2% by mass of titanium, 57% by mass of chlorine, 21% by mass of magnesium, and 20% by mass of DIBP.

[0083] (2) Production of prepolymerization catalyst 87.5 g of solid titanium catalyst, 99.8 mL of triethylaluminum, 28.4 mL of diethylaminotriethoxysilane, and 12.5 L of heptane were placed in a 20 L autoclave equipped with a stirrer. Maintaining an internal temperature of 15°C to 20°C, 875 g of propylene was added, and the mixture was reacted with stirring for 100 minutes. After polymerization was complete, the solid components were allowed to settle, and the supernatant was removed and washed twice with heptane. The resulting prepolymerization catalyst was resuspended in purified heptane and adjusted with heptane to a solid titanium catalyst concentration of 0.7 g / L.

[0084] (3) Preparation of propylene polymer particles A jacketed, circulating tubular polymerization reactor with a capacity of 58 L was continuously supplied with 40 kg / hour of propylene, 123 NL / hour of hydrogen, 0.30 g / hour of prepolymerization catalyst, 2.1 mL / hour of triethylaluminum, and 0.88 mL / hour of diethylaminotriethoxysilane, and polymerization was carried out in a completely liquid state without a gas phase. The temperature of the tubular polymerization reactor was 70°C and the pressure was 3.3 MPa / G. The resulting slurry was sent to a 100L vessel polymerizer equipped with a stirrer for further polymerization. Propylene was supplied to the polymerizer at a rate of 15 kg / hour, and hydrogen was supplied to maintain a hydrogen concentration of 3.0 mol% in the gas phase. Polymerization was carried out at a temperature of 70°C and a pressure of 3.1 MPa / G. The obtained slurry was transferred to a 2.4 L transfer tube, where it was gasified and gas-solid separation was performed. Then, the polypropylene homopolymer powder was sent to a 480 L gas-phase polymerization reactor for ethylene-propylene copolymerization. Here, propylene, ethylene, and hydrogen were continuously supplied to the gas-phase polymerizer so that the gas composition was ethylene / (ethylene + propylene) = 0.15 (molar ratio of ethylene) and hydrogen / ethylene = 4.0 (molar ratio). Polymerization was carried out at a polymerization temperature of 70°C and a pressure of 1.9 MPa / G, followed by vacuum drying at 80°C to obtain propylene-based polymer particles composed of propylene-ethylene block copolymer.

[0085] (4) Mechanical crushing The propylene polymer particles obtained above were cooled to approximately -150°C with liquid nitrogen and pulverized using a pulverizer (Linlex mill) to obtain a resin powder (PP1) containing propylene polymer powder.

[0086] The physical properties of PP1 obtained in Example 1 are as follows: -Physical properties of PP1- Volume-average particle size: 70 μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 167℃ Heat of fusion: 90 J / g 23℃ n-decane soluble portion: 9% by mass

[0087] [Example 2] Propylene-based polymer particles composed of propylene-ethylene block copolymer were obtained in the same manner as in Example 1, except that the gas composition in the vapor polymerization reactor was set to ethylene / (ethylene + propylene) = 0.17 (ethylene content molar ratio). Furthermore, mechanical grinding treatment was performed in the same manner as in Example 1 to obtain resin powder (PP2) containing propylene-based polymer powder. The physical properties of PP2 obtained in Example 2 are as follows:

[0088] -Physical properties of PP2- Volume-average particle size: 70 μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 166℃ Heat of fusion: 113 J / g 23℃ n-decane soluble portion: 10% by mass

[0089] [Example 3] A propylene-based polymer particle composed of a propylene-ethylene block copolymer was obtained in the same manner as in Example 1, except that the ratio of ethylene to ethylene was set to 0.20 (molar ratio of ethylene content). Furthermore, a mechanical grinding treatment was performed in the same manner as in Example 1 to obtain a resin powder (PP3) containing the propylene-based polymer powder.

[0090] The physical properties of the PP3 obtained in Example 3 are as follows. -Physical properties of PP3- Average particle size: 70μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 166℃ Heat of fusion: 102 J / g 23℃ n-decane soluble portion: 12% by mass

[0091] [Comparative Example 1] A propylene-based polymer particle composed of a propylene-ethylene block copolymer was obtained in the same manner as in Example 1, except that the ratio of ethylene to ethylene was set to 0.3 (molar ratio of ethylene content). Furthermore, a mechanical grinding treatment was performed in the same manner as in Example 1 to obtain a resin powder (PP4) containing the propylene-based polymer powder.

[0092] The physical properties of PP4 obtained in Comparative Example 1 are as follows: -Physical properties of PP4- Volume-average particle size: 70 μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 165℃ Heat of fusion: 65 J / g 23℃ n-decane soluble portion: 17% by mass

[0093] [Comparative Example 2] A propylene-based polymer particle composed of a propylene-ethylene block copolymer was obtained in the same manner as in Example 1, except that the ratio of ethylene / (ethylene + propylene) = 0.11 (ethylene content molar ratio). Furthermore, a mechanical grinding treatment was performed in the same manner as in Example 1 to obtain a resin powder (PP5) containing the propylene-based polymer powder.

[0094] The physical properties of PP5 obtained in Comparative Example 2 are as follows. -Properties of PP5- Volume-average particle size: 70 μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 165℃ Heat of fusion: 100 J / g 23℃ n-decane soluble portion: 5% by mass

[0095] [Comparative Example 3] A propylene-based polymer particle composed of a propylene-ethylene block copolymer was obtained in the same manner as in Example 1, except that the ratio of ethylene / (ethylene + propylene) was set to 0.18 (molar ratio of ethylene content). Furthermore, a mechanical grinding treatment was performed in the same manner as in Example 1 to obtain a resin powder (PP6) containing propylene-based polymer powder.

[0096] The physical properties of PP6 obtained in Comparative Example 3 are as follows. -Physical properties of PP6- Volume-average particle size: 70 μm MFR (230℃, under 2.16kg load): 20g / 10min Melting point: 166℃ Heat of fusion: 125 J / g 23℃ n-decane soluble portion: 10% by mass

[0097] Table 1 shows the properties of the resin powders containing propylene polymer powders from Examples 1-3 and Comparative Examples 1-3, and the three-dimensional molded articles thereof.

[0098] [Table 1]

[0099] As shown in Table 1, the impact strength of the molded body (formed object) using resin powders PP1 to PP3 of Examples 1 to 3 showed little change compared to the case where resin powders PP4 to PP6 of Comparative Examples 1 to 3 were used for three-dimensional molding, indicating that the mechanical strength was maintained before and after molding. The resin powders of this disclosure can be reused in the powder bed fusion method.

Claims

1. A resin powder containing a propylene polymer powder and satisfying the following conditions (a-1) and (b). (a-1) The heat of fusion (ΔH) calculated by differential scanning calorimetry (DSC) in accordance with ISO 3146 is 70 J / g or more and less than 125 J / g. (b) Amount of n-decane soluble at 23°C (D ｓｏｌ ) is the amount of n-decane soluble at 23°C (D ｓｏｌ ) and the insoluble portion of n-decane at 23°C (D ｉｎｓｏｌ It is 6.0% to 15.0% by mass relative to the total mass of ( ).

2. The resin powder according to claim 1, further satisfying (a-2) below. (a-2) Melting point (T) measured by differential scanning calorimetry (DSC) in accordance with ISO 3146 standard ｍ The temperature is between 150°C and 170°C.

3. The resin powder according to claim 1, further satisfying (c-1) below. (c-1) When the first three-dimensional molded body is formed by powder bed fusion bonding, the Charpy impact strength (with notch) of the first three-dimensional molded body, measured according to ISO 179-1 standard, is 2.0 kJ / m at 23°C. ２ That's all.

4. The resin powder according to claim 3, further satisfying (c-2) below. (c-2) When the surplus resin powder from the first three-dimensional molded body is reused to form the next three-dimensional molded body by the powder bed fusion bonding method, the rate of change in the Charpy impact strength (notched) measured according to ISO 179-1 standard between the first three-dimensional molded body and the next three-dimensional molded body ([(Charpy impact strength (notched) of the first three-dimensional molded body - Charpy impact strength (notched) of the next three-dimensional molded body) / Charpy impact strength (notched) of the first three-dimensional molded body] × 100) is 10% or less.

5. The resin powder according to claim 1, used for three-dimensional molding.

6. A three-dimensional molded body formed using the resin powder described in any one of claims 1 to 5.

7. A method for manufacturing a three-dimensional molded article, comprising manufacturing a three-dimensional molded article by powder bed fusion bonding using the resin powder described in any one of claims 1 to 5.

Images