Mixture, resin, filament and compact

Abstract

To provide a mixture, a resin, a filament and a compact, which can be preferably used in three-dimensional printing of a FFF system using inorganic powder.SOLUTION: As a result of intensive research, the inventors of the present technology have discovered that by using a three-component resin containing a low-melting point component, a flexible component, and a structure-maintaining component as the resin to be mixed with the inorganic powder, it is possible to reduce the frequency of a filament breaking in a filament feed section or inside an ejector of a 3D printer when extruded from a nozzle of the 3D printer as a filament for the 3D printer, thereby making it possible to realize efficient 3D printing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present technology relates to a mixture, a resin, a filament, and a molded body. More specifically, the present technology relates to a mixture, a resin, a filament, and a molded body suitable for three-dimensional printing by a fused filament fabrication (FFF) method using inorganic powder. [Background technology]

[0002] 2. Description of the Related Art Compositions using inorganic powders for use in three-dimensional printing have been known.

[0003] For example, the following Patent Document 1 discloses a composition suitable for 3D printing, which contains a metal and / or ceramic powder, a binder, and poly(ethylene vinyl acetate), and a filament coil containing the composition. However, there is a concern that the filament may break frequently in the filament feed section of the 3D printer depending on the extrusion conditions from the nozzle of the 3D printer used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-509549 Summary of the Invention [Problem to be solved by the invention]

[0005] The main objective of this technology is to provide a mixture, resin, filament, and molded body that can be suitably used for FFF-type 3D printing using inorganic powder. [Means for solving the problem]

[0006] As a result of extensive research, the inventors of this technology have discovered that by using a three-component resin containing a low-melting point component, a flexible component, and a structure-maintaining component as the resin to be mixed with the inorganic powder, it is possible to reduce the frequency of the filament breaking in the filament feed section or inside the ejector of a 3D printer when extruded from the nozzle of the 3D printer as a filament for the 3D printer, thereby making it possible to realize efficient 3D printing.

[0007] That is, the present technology provides a mixture of inorganic powder and resin, the resin including a low melting point component consisting of one or more compounds selected from wax, low molecular weight polyethylene, and low molecular weight polypropylene, a flexible component consisting of one or more compounds selected from EVA, elastomer, and polyurethane, and a structure maintaining component selected from polyolefin, polystyrene, PMMA, PLA, and PET. The elastomer used as the flexible component in the mixture provided by the present technology may be a styrene-based elastomer. The mixture provided by the present technology may be such that, relative to 100 vol% of the resin, the low melting point component is 24 to 50 vol%, the flexibility component is 24 to 60 vol%, and the structure maintaining component is 0 to 36 vol%. Alternatively, relative to 100 vol% of the resin, the low melting point component may be 40 to 50 vol%, the flexibility component is 24 to 36 vol%, and the structure maintaining component is 16 to 36 vol%. Furthermore, relative to 100 vol% of the resin, the low melting point component may be 40 to 50 vol%, the flexibility component is 24 to 36 vol%, and the structure maintaining component is 16 to 30 vol%. The mixture provided by the present technology may contain 35 to 60 vol% of the inorganic powder, or 40 to 55 vol% of the inorganic powder, relative to 100 vol% of the mixture. The mixture provided by the present technology may further contain a surfactant. When the mixture provided by the present technology contains a surfactant, the surfactant may be 3 vol% or less relative to 100 vol% of the resin. The mixture provided by the present technology can be suitably used as a filament, preferably a filament for a three-dimensional printer. Furthermore, the present technology provides a molded article manufactured using the filament according to the present technology. [Brief description of the drawings]

[0008] [Figure 1] 1 shows a component diagram of the resin according to the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A preferred embodiment of the present technology will be described below. However, the embodiment described below is an example of a typical embodiment of the present technology, and the present technology is not limited to only the preferred embodiment described below and can be freely modified within the scope of the present technology.

[0010] <Mixture> The mixture according to the present technology is formed by mixing inorganic powder and resin. Here, "mixing" means mixing. Also, "mixture" means a state in which multiple substances are mixed, specifically, a state in which inorganic powder and resin are mixed. In this case, it is preferable that the inorganic powder and the resin are not chemically bonded.

[0011] The inorganic powder contained in the mixture according to the present technology can be suitably adjusted to any range, such as 35 vol% or more, 40 vol% or more, 45 vol% or more, 50 vol% or more, 55 vol% or more, 60 vol% or more, relative to 100 vol% of the mixture. By increasing the content ratio of the inorganic powder relative to 100 vol% of the mixture, the amount of resin used is reduced, making it easier to bring the density of the molded body after sintering closer to 100%. In addition, the shrinkage rate during sintering of the molded body is reduced, making it easier to control the dimensions of the molded product.

[0012] The upper limit of the content ratio of the inorganic powder contained in the mixture according to the present technology relative to 100 vol% of the mixture is not particularly limited, but can be suitably adjusted within any range, such as 65 vol% or less, 60 vol% or less, 55 vol% or less, 50 vol% or less, 45 vol% or less, 40 vol% or less, etc. For example, from the viewpoint of improving the mechanical properties such as the handleability and shapeability of the filament using the mixture according to the present technology, the upper limit of the content ratio of the inorganic powder relative to 100 vol% of the mixture can be set according to the purpose and application of the mixture according to the present technology.

[0013] <Inorganic powder> The inorganic powder used in the mixture of the present technology is not particularly limited as long as it is a sinterable inorganic compound. For example, metal powder and / or ceramic powder can be mentioned. Here, "sintering" refers to the phenomenon in which, when a powder is pressure molded and heat-treated at a temperature below the melting point, bonds are formed between powder particles and the powder solidifies into a molded shape. In addition, "metal powder and ceramic powder" includes a mixed powder of a metal powder and a ceramic powder.

[0014] The "metal" of metal powder includes any element of the periodic table selected from the alkali metals, alkaline earth metals, lanthanides, actinides, transition metals, non-metallic metals and metalloids, and any compound in which the corresponding atoms are bonded by metallic bonds.

[0015] The "metal powder" may comprise or consist of one or more elements selected from alkali metals, alkaline earth metals, lanthanides, actinides, transition metals, poor metals, metalloids, metal oxides, metal carbides, metal borides, and metal nitrides, such as yttrium, yttrium oxide, copper, tin, aluminum, cerium, cerium oxide, uranium, uranium oxide, iron, iron oxide, steel, tungsten, tungsten carbide, strontium titanate, silicon carbide, silicon dioxide, aluminum oxide, zirconium dioxide, titanium dioxide, cobalt dioxide, or manganese dioxide, transition metal oxides, barium, barium titanate, lead zirconate titanate (LZT), and mixtures thereof. It may also be a piezoelectric powder selected from titanates, ferrites, tantalates, niobates and tungsten bronze compounds, more preferably barium titanate, lead titanate, potassium niobate, lithium niobate, bismuth ferrite, lithium tantalate and lead zirconate titanate (LZT).

[0016] The "ceramic" in ceramic powder refers to any clay-based material or any non-metallic and inorganic material obtained upon heating.

[0017] The "ceramic powder" comprises or consists of one or more components selected from carbides, sulfides, halides, oxides, hydroxides, carbonates, borates, sulfates, chromates, nitrates, molybdates, tungstates, phosphates, arsenates, vanadates, silicates, and aluminosilicates, among others.

[0018] <Resin> The resin used in the mixture of the present technology contains at least three components, a low melting point component, a flexible component, and a structure maintaining component, and can agglomerate the aforementioned inorganic powder. Furthermore, the mixture may be subsequently removed by sintering. Here, the term "resin" refers to one or more polymeric compounds.

[0019] <Low melting point component> The low melting point component contained in the resin of the present technology is a low melting point polymer compound or a mixture thereof that can be degreased with a solvent, such as wax, low molecular weight polyethylene, low molecular weight polypropylene, etc. Examples of the wax include paraffin wax, microcrystalline wax, beeswax, carnauba wax, Japan wax, palm wax, etc.

[0020] The low molecular weight polyethylene may preferably be a compound having an upper molecular weight of, for example, 15,000 g / mol or less, 12,000 g / mol or less, 10,000 g / mol or less, etc. The low molecular weight polypropylene may preferably be a compound having an upper molecular weight of, for example, 15,000 g / mol or less, 12,000 g / mol or less, 10,000 g / mol or less.

[0021] The above-mentioned paraffin wax and microcrystalline wax can be degreased by extraction with dichloromethane, bromine-based solvent Absol, acetone, hexane, heptane, petroleum ether, ethyl acetate, ethanol, methanol, propanol, supercritical CO2, etc. Low molecular weight polyethylene can be degreased by extraction with cyclohexane, etc. In addition, the solvent degrease treatment can be suitably performed by heating to room temperature or an appropriate temperature below the boiling point according to the characteristics of the low melting point component to be extracted. The low melting point component contained in the resin of the present technology may be one type of polymer compound or a combination of multiple types of polymer compounds.

[0022] Being capable of being degreased by a solvent means that some or all of the components of the resin can be dissolved from the target by a solvent, specifically, it means that some or all of the components that make up the resin of the present technology can be removed by immersing the molded body of the present technology in a solvent.

[0023] The upper limit of the melting point of the low melting point component contained in the resin of the present technology is, for example, 140° C. or less, preferably 120° C. or less, and more preferably 100° C. or less. The lower limit of the melting point of the wax is not particularly limited, but for example, waxes having a melting point of 60° C. or more, such as paraffin wax and microcrystalline wax which is a fractional distillation component of the paraffin wax, can be suitably used.

[0024] The ratio of the low melting point component contained in the resin of the present technology can be suitably adjusted within a range of, for example, 20 vol% or more, 24 vol% or more, 28 vol% or more, 36 vol% or more, 40 vol% or more, 44 vol% or more, etc., relative to 100 vol% of the resin. The upper limit of the ratio of the low melting point component to 100 vol% of the resin can be suitably adjusted within a range of, for example, 50 vol% or less, 49 vol% or less, 48 ​​vol% or less, etc. By containing a wax or the like, which is a low melting point component, the temperature at which the resin is processed can be relatively low, improving the handleability.

[0025] <Flexibility component> The flexibility component contained in the resin of the present technology is a polymer compound or a mixture thereof that can improve the flexibility of the resin of the present technology. Examples include ethylene vinyl acetate (EVA) and elastomers. The flexibility component contained in the resin of the present technology may be one type of polymer compound or a combination of multiple types of polymer compounds.

[0026] Here, the aforementioned ethylene vinyl acetate is a copolymer of ethylene and vinyl acetate. Depending on the ratio of vinyl acetate in the copolymer, there are generally three types of ethylene vinyl acetate: EVA with low vinyl acetate content, EVA with medium vinyl acetate content, and EVA with high vinyl acetate content. In the present technology, any of the vinyl acetates can be suitably used.

[0027] The elastomer is a polymeric compound having high elasticity at room temperature, and examples thereof include styrene-based elastomers and acrylic elastomers. The styrene-based elastomer is a rubber-like polymeric material mainly composed of styrene. The styrene content of the styrene-based elastomer that can be suitably used in the present technology is, for example, 15 to 30 wt%. Examples of the styrene-based elastomer include SEPS (styrene-ethylene-propylene-styrene), SEEPS (styrene-ethylene-ethylene-propylene-styrene), SEBS (styrene-ethylene-butylene-styrene), TPU (Thermoplastic Polyurethane), and various styrene block polymeric elastomers made of copolymers of styrene and butadiene. The acrylic elastomer is a rubber-like polymeric material mainly composed of acrylic ester. The acrylic content of the acrylic elastomer that can be suitably used in the present technology is, for example, 20 to 30 wt%. Examples of acrylic elastomers include a copolymer of methyl methacrylate and n-butyl acrylate, and a copolymer of methyl methacrylate and 2-ethylhexyl acrylate.

[0028] The ratio of the flexible component contained in the resin of the present technology can be suitably adjusted, for example, in the range of 20 vol% or more, 22 vol% or more, 24 vol% or more, etc., relative to 100 vol% of the resin. The upper limit of the ratio of the flexible component relative to 100 vol% of the resin can be suitably adjusted, for example, in the range of 68 vol% or less, 64 vol% or less, 60 vol% or less, 40 vol% or less, 36 vol% or less, 34 vol% or less, etc. When ethylene vinyl acetate or a styrene-based elastomer is mainly used as the flexible component, the ratio of the flexible component relative to 100 vol% of the resin may be adjusted to a low region, such as 30 vol% or less, within the above-mentioned range. In this case, the ratio of the low-melting point component relative to 100 vol% of the resin may be adjusted to a region of 40 vol% or more, for example. On the other hand, when an acrylic-based elastomer is used as the flexible component, the ratio of the flexible component relative to 100 vol% of the resin may be adjusted to a high region, such as 30 vol% or more, within the above-mentioned range.

[0029] <Structure maintaining component> The structural maintaining component contained in the resin of the present technology is a polymer compound or a mixture thereof that can ensure the structural strength of the filament or molded body using the resin of the present technology. Examples include polyethylene (PE), polypropylene (PP), styrene resin, polymethyl methacrylate (PMMA), polylactic acid (PLA), PET, phenolic resin, polypropylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyethylene glycol, polyvinyl alcohol, polyamide, polyvinylpyrrolidone, polyacrylate, polyamide, polycarbonate, etc.

[0030] The ratio of the structure-maintaining component contained in the resin of the present technology is not particularly limited in terms of the lower limit of the ratio to 100 vol% of the resin. For example, it can be suitably adjusted within a range of 0 vol% or more, more than 0 vol%, 14 vol% or more, 16 vol% or more, 18 vol% or more, etc. The upper limit of the ratio of the structure-maintaining component to 100 vol% of the resin can be suitably adjusted within a range of, for example, 38 vol% or less, 36 vol% or less, 34 vol% or less, 32 vol% or less, 30 vol% or less, 28 vol% or less, etc.

[0031] <Surfactant> The resin of the present technology may further contain a surfactant depending on the purpose and application of the mixture of the present technology. The surface active agent that can be used in the present technology is not particularly limited, but for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be appropriately selected according to the application. Examples of anionic surfactants include stearates and palmitates.

[0032] When the resin of the present technology contains a surfactant, the content of the surfactant can be suitably adjusted to, for example, 3 vol% or less, 2 vol% or less, 1 vol% or less, 0.5 vol% or less, etc., relative to 100 vol% of the resin.

[0033] <Resin manufacturing method> There is no limitation on the method for producing the resin of the present technology, and a known method for producing a resin can be suitably used, such as a method in which the components are mixed in advance using various mixers such as a tumbler, a Henschel mixer, or a super mixer, and then the components are melt-kneaded using a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader.

[0034] <Filament> The mixture of the present technology can be processed into a filament having any diameter. Here, the "filament" refers to a cylindrical molded body having any diameter, and is distributed, for example, in the form of a coil wound around a reel. For example, the filament can be used as a filament for a three-dimensional printer. In this case, the filament is extruded from the nozzle of a three-dimensional printer and processed into a molded body having any shape by the three-dimensional printer.

[0035] Here, the shape of the filament for a 3D printer of the present technology can be any shape, for example, a thin wire shape of any diameter, as an exchangeable supply form according to the specifications of a known 3D printer. The mixture of the present technology has a good balance of flexibility and strength, and by using it as a filament for a 3D printer, the frequency of breakage when extruded from the nozzle of the 3D printer can be reduced, and 3D printing can be efficiently realized. Furthermore, the modeling property of the modeling sample, which is a molded body by the 3D printer, can be ensured.

[0036] As mentioned above, the diameter of the filament for 3D printers using this technology can be adjusted to any value according to the specifications of the 3D printer. In general 3D printers, for example, the diameter is generally 1.65 mm or more, 1.75 mm or less, or 3 mm or less, 2.75 mm or more. It is desirable for the filament diameter to be as uniform as possible.

[0037] The length of the filament for the 3D printer of the present technology is not particularly limited as long as it is a replaceable supply form that matches the specifications of the 3D printer, but can be adjusted to, for example, 1 m or more, 40 m or more, 80 m or more, etc. The upper limit of the filament length can be adjusted within a range of, for example, 3000 m or less, 1500 m or less, 1200 m or less, etc.

[0038] It is preferable that the filament for a 3D printer be easily bent and not easily broken. Specifically, it is desirable that the filament for a 3D printer of this technology has an appropriate balance between flexibility and strength.

[0039] The flexibility of a filament for a three-dimensional printer can be evaluated, for example, by a loop test (a method in which a filament is looped, its radius is gradually reduced, and the flexibility is evaluated from the radius at the time of breakage). When the filament diameter is 1.75 mm, the filament for a three-dimensional printer of the present technology can achieve, for example, 40 mm or less, preferably 30 mm or less, and more preferably 20 mm or less, as evaluated by the loop test.

[0040] As an index of strength of a filament for a three-dimensional printer, for example, an evaluation in a three-point bending test (JIS Z2248:2006) with a gauge length of 5 cm and a filament diameter of 1.75 mm can be used. The filament for a three-dimensional printer of the present technology can achieve, for example, 0.55 N or more, preferably 0.65 N or more, and more preferably 0.75 N or more as an evaluation in a three-point bending test with a gauge length of 5 cm and a filament diameter of 1.75 mm.

[0041] The filament for 3D printers of this technology uses a three-component resin containing a low melting point component, a flexible component, and a structure maintaining component as the resin to be mixed with the inorganic powder, which provides an appropriate balance between flexibility and strength and allows it to be suitably coiled. Furthermore, the frequency of breakage in the filament feed section or inside the ejector of the 3D printer when extruded from the nozzle of the 3D printer is reduced, making it possible to realize efficient 3D printing.

[0042] <3D printer> The 3D printer filament made of the mixture of this technology can be used, for example, in FFF 3D printing, which is a 3D printing method in which a 3D printer ejects the 3D printer filament from a nozzle and stacks the ejected material by moving the nozzle.

[0043] Examples of manufacturing processes for molded objects by 3D printing using the 3D printer filament of the present technology include, but are not limited to, the following. a) a supplying step of supplying the filament for the 3D printer of the present technology to the 3D printer, and then b) a printing step of printing the pre-sintered compact; c) optionally, a solvent degreasing step in which the resin of the present technology is removed by immersing the pre-sintered compact in a solvent; d) a heat degreasing step for removing a resin component from the molded body of step (b) or from the molded body of step (c); e) a sintering step of sintering the heated degreased body by heating to obtain a molded body; and f) optionally, a smoothing step for smoothing the pre-sintered compact of step (b) or the compact of step (e). Each step will be described below.

[0044] <Supply process> The supplying step is a step of supplying the filament for a 3D printer of the present technology to the 3D printer. The method of supplying the filament for a 3D printer of the present technology is not particularly limited, and a known method of supplying a filament can be adopted. Since the filament of the present technology has an appropriate balance between flexibility and strength, it is possible to reduce the frequency of the filament breaking in the filament feeding section of the 3D printer or inside the ejector when it is extruded from the nozzle of the 3D printer, thereby realizing efficient 3D printing.

[0045] <Printing process> The printing process is a process of stacking the 3D printer filament supplied by extrusion from the nozzle of the 3D printer in the supply process to form a pre-sintered compact (3D printing). The printing method using the 3D printer filament of the present technology is not particularly limited as long as it is an FFF method, and a known FFF method of 3D printing can be suitably adopted.

[0046] <Solvent degreasing process> The solvent degreasing process is a process in which the pre-sintered molded body formed by the printing process is immersed in a solvent to preliminarily remove part of the resin components of this technology. This process is an optional process and is not essential in the manufacturing process of molded bodies by 3D printing.

[0047] By preliminarily degreasing the resin from the pre-sintered molded body by solvent degreasing treatment, it is possible to suppress the occurrence of so-called "sagging," in which the surface of the molded body melts and its shape changes during the subsequent heating degreasing process or sintering process, and it is also possible to prevent the molded body from cracking or swelling during the heating degreasing process or sintering process.

[0048] The solvent degreasing process is carried out by immersing the pre-sintered compact in one or more solvents selected from, for example, acetone, hexane, heptane, gasoline, ethyl acetate, ethanol, methanol, propanol, dichloromethane, Absol, supercritical CO2, cyclohexane, and water, depending on the low melting point component such as wax used.

[0049] The solvent degreasing treatment can be suitably carried out, for example, by immersing the pre-sintered compact in a solvent at room temperature to 80° C. for 1 hour to 72 hours.

[0050] <Heating degreasing process> The thermal degreasing process is a process for removing resin components from a pre-sintered molded body. If the manufacturing process for a molded body by 3D printing does not include a solvent degreasing process, the resin of the technology is removed by a thermal degreasing process performed prior to the sintering process. Even if a solvent degreasing process is performed, a thermal degreasing process is included to sufficiently remove the remaining resin components. In this case, it is preferable to perform heating with a slow heating gradient in order to avoid bubble formation due to evaporation of the resin and / or calcination of the resin during sintering. The heating gradient condition in this case is, for example, 10°C / hour to 100°C / hour.

[0051] <Sintering process> The sintering step is a step of sintering the pre-sintered compact by heating to obtain a compact. The sintering step may be performed under vacuum conditions or in an inert atmosphere in the case of metals, and may be performed in the air in the case of ceramics. The temperature conditions for sintering metals are, for example, 800°C to 1300°C. The temperature conditions for sintering ceramics are, for example, 1300°C to 1700°C.

[0052] <Smoothing process> The smoothing step is a step of smoothing the pre-sintered compact or the molded body. The smoothing step is, for example, smoothing the pre-sintered compact or the molded body by contacting it with a solvent that makes it possible to reduce the unevenness of the surface of the pre-sintered compact or the molded body. This step is an optional step and is not an essential step in the manufacturing process of a molded body by 3D printing.

[0053] As the solvent used in the smoothing step, depending on the characteristics of the pre-sintered compact or compact, for example, a compound selected from hexane, heptane, octane and mixtures thereof, gasoline, white spirit (also known as solvent naphtha, a mixture of aliphatic, open-chain or alicyclic C7 to C12 hydrocarbons), benzene, toluene, ortho-, para- or meta-dimethylbenzene and mixtures thereof, tetrahydrofuran, 2-methyltetrahydrofuran and mixtures thereof can be used.

[0054] A known means can be suitably used as a means for contacting the pre-sintered compact or the surface of the compact with the solvent. For example, the pre-sintered compact or the compact may be immersed in the solvent. The solvent may be applied to the surface of the pre-sintered compact or the compact using a brush or the like. The solvent may be sprayed onto the surface of the pre-sintered compact or the compact. EXAMPLES

[0055] The present technology will be described in more detail below using examples. Note that the present technology is not limited to the contents of the examples shown below.

[0056] <Raw materials> The resins and raw materials contained in the mixtures of the examples are shown below. [Low melting point components] Paraffin wax (Paraffin wax melting point 66-68℃ / Wako Pure Chemical Industries, Ltd.) Microcrystalline wax (HIMIC-1090 / Nippon Seiro) [Flexibility component] (EVA) Ethylene vinyl acetate (Evaflex V406 / Mitsui Dow Polychemical) (Elastomer) Styrene-based elastomer SEPS (SP4033 / Kuraray) SEEPS (SP2004F / Kuraray) SEBS (SP8004 / Kuraray) Highly flexible styrenic elastomer: Vinyl SEEPS (F7311F / Kuraray) Acrylic elastomer: Kurarity (LA2140 / Kuraray) Kurarity (LA2250 / Kuraray) Kurarity (LA2320 / Kuraray) (Polyurethane) Ether-based polyurethane (E380 / Nihon Miractoran) [Structure-maintaining component] Polypropylene (J107G / Prime Polymer) PLA (3D850 / NatureWorks) [Inorganic powder] Stainless steel (SUS316L) (PF3F, PF5F, PF10F, PF20F / Epson Atmix)

[0057] [Example 1] <Filament manufacturing> The above raw materials were mixed in the ratios shown in Table 1, and then combined with inorganic powder (stainless steel powder / PF10F) and mixed at 160-230℃ using a bamboo spatula under heating conditions using a hot plate (Tiger hot plate CPH-DI30 / Tiger Thermos) to obtain a mixture. Note that 45 vol% of the inorganic powder was added to 100 vol% of the mixture. The component diagram in Figure 1 shows the position of the resins shown in Table 1.

[0058] The resulting mixture was extruded by an extruder (WELLZOOM / SHENZHEN Mister Technology) to produce filaments having a diameter of φ1.75 mm and a length of 10 m or more.

[0059] [Table 1]

[0060] <Three-point bending test> Each of the produced filaments was measured with a gauge length of 5 cm, and the conditions other than the test specimen were measured in accordance with JIS Z2248:2006. The results are shown in Table 2.

[0061] <Loop test> Each of the produced filaments was measured according to the above-mentioned test method, and the results are shown in Table 2.

[0062] <Formability> Each of the filaments produced was used to print a pre-sintered compact using a 3D printer (Creality / Ender-3). It was confirmed that each of the filaments produced could be continuously fed by extrusion from the nozzle without breaking in the filament feed section or inside the injector of the 3D printer, and that a pre-sintered compact could be formed by stacking them.

[0063] For A and D shown in Table 1, we attempted to print pre-sintered molded bodies using a 3D printer under similar conditions as described above using filaments created by the method described above using a mixture that did not contain polypropylene, which is the structural maintaining component, and that did not change the ratio of paraffin wax, which is the low-melting point component, and ethylene vinyl acetate, which is the flexible component; however, there were cases in which the filament was not supplied continuously (by being melted to the nozzle), making it impossible to print.

[0064] The obtained pre-sintered compact was immersed in a bromine-based solvent (ABZOL / Albemarle) for 4 hours under stirring conditions at 40° C. This solvent degreasing process preliminarily removed a portion of the components of each resin.

[0065] The pre-sintered compact was then heated and degreased in a sintering furnace (Siliconit electric furnace / Siliconit Co., Ltd.), and then sintered at 1150°C for 2 hours using a vacuum (atmospheric pressure of approximately 5 Pa) produced by a rotary pump to obtain a compact.

[0066] Regarding formability, a model for benchmarking a small boat, known as #Benchy3D by CreativeTools, was created, and the five characteristic points shown below were evaluated by five judges based on the following evaluation criteria. The evaluation results were calculated by averaging the scores given by the judges. The results are shown in Table 2. The five characteristic points are the chimney, the cabin roof undercut, the cabin pillars, the bow rope hole, and the side of the hull. 5: Reproducibility of all five characteristic points is guaranteed. 4: Of the five characteristic points, reproducibility of four points is guaranteed. 3: Of the five characteristic points, reproducibility of three points is guaranteed. 2: Of the five characteristic points, reproducibility of two points is guaranteed. 1: Of the five feature points, reproducibility of one point is guaranteed. 0: Of the five characteristic points, none are reproducible.

[0067] For each filament, the results of the three-point bending test, loop test, and moldability were quantified according to the following criteria.

[0068] [Three-point bending test] 3: 1.4N or more 2: 1.2N or more 1: 1.0N or more 0: Less than 1.0N

[0069] [Loop test] 3: 50mm or less 2: 85mm or less 1: 100mm or less 0: Less than 100mm

[0070] [Formability evaluation results] 3: 4.5 or higher 2: 4.0 or higher 1: 2.4 or higher 0: Less than 2.4

[0071] For each filament, a comprehensive evaluation was performed based on the total values ​​of the three-point bending test, loop test, and moldability quantified above, according to the following evaluation criteria. The results are shown in Table 2. A: 5 points or more B: 4 points C: 3 points D: 2 points or less

[0072] [Table 2]

[0073] [Example 2] The mixtures used for the respective molded bodies in Example 1 were mixed in the combinations shown in Table 3, and filaments were produced under the same conditions as in Example 1. The same measurements as in Example 1 were carried out using the respective obtained filaments. In this case, it was also confirmed that the respective filaments produced were continuously supplied by extrusion from the nozzle of the three-dimensional printer without breaking at the filament feed section of the printer, and that a pre-sintered molded body could be formed by stacking them. The results are shown in Table 3.

[0074] [Table 3]

[0075] [Example 3] Filaments were produced under the same conditions as in Example 1, except that the compound shown in Table 3 was used instead of ethylene vinyl acetate as the flexible component of the resin used in the molded body E of Example 1. The same measurements as in Example 1 were performed using each of the obtained filaments. In this case, it was confirmed that each of the produced filaments was continuously supplied by extrusion from the nozzle of the three-dimensional printer without breaking at the filament feeding section of the three-dimensional printer when extruded from the nozzle of the three-dimensional printer, and that a pre-sintered molded body could be formed by stacking. The results are shown in Table 4.

[0076] [Table 4]

[0077] [Example 4] For the resins G, J to L, and O to R shown in the composition diagram of FIG. 1, the flexible component was replaced with ethylene vinyl acetate, and the above-mentioned styrene-based elastomer SP4033 and acrylic-based elastomer (LA2140 / Kuraray) were blended at a volume ratio of 1:2. Except for this, filaments were produced under the same conditions as in Example 1. The same measurements as in Example 1 were performed using each of the obtained filaments. In this case, it was confirmed that each of the produced filaments was continuously supplied by extrusion from the nozzle of the three-dimensional printer without breaking at the filament feed section of the three-dimensional printer when extruded from the nozzle of the three-dimensional printer, and that a pre-sintered molded body could be formed by stacking. The results are shown in Table 5. Furthermore, for the resins G and J to L, and O to R shown in the composition diagram of Figure 1, it was confirmed that the filaments produced under the same conditions as in Example 4 except that LA2250 was used instead of LA2140 as the acrylic elastomer, and the filaments produced under the same conditions as in Example 4 except that LA2330 was used, were each extruded from the nozzle of a 3D printer without breaking in the filament feed section of the printer, but were continuously supplied by extrusion from the nozzle, and could be stacked to form a pre-sintered molded body.

[0078] [Table 5]

[0079] [Example 5] For the resin R shown in the component diagram of Figure 1, the flexible component was changed to ethylene vinyl acetate, and a styrene-based elastomer (SP4033 / Kuraray), an acrylic elastomer (LA2140 / Kuraray), and a polyurethane (E380 / Nippon Miractoran) were mixed in a volume ratio of 1:2:2. Except for this, a filament was produced under the same conditions as in Example 1, and named filament R-α. Similarly, for resin R shown in the component diagram of Figure 1, the flexible component was replaced with ethylene vinyl acetate, and a styrene-based elastomer (SP4033 / Kuraray) and an acrylic elastomer (LA2140 / Kuraray) were mixed in a volume ratio of 1:2, and the structure-maintaining component was replaced with PLA (3D850 / NatureWorks) instead of polypropylene. Except for this, a filament was produced under the same conditions as in Example 1, and named filament R-β. Furthermore, for the resin R shown in the component diagram of Figure 1, the flexible component was replaced with ethylene vinyl acetate, and a styrene-based elastomer (SP4033 / Kuraray) and a highly flexible styrene-based elastomer (F7311F / Kuraray) were blended in a volume ratio of 2:1. Except for this, a filament was produced under the same conditions as in Example 1, and named filament R-γ. The same measurements as in Example 1 were carried out using each of the obtained filaments. In this case, too, it was confirmed that each of the produced filaments was not broken at the filament feed section of the three-dimensional printer when extruded from the nozzle of the three-dimensional printer, was continuously extruded from the nozzle, and was able to be stacked to form a pre-sintered compact. The results are shown in Table 6.

[0080] [Table 6]

[0081] In addition, the present technology can have the following configurations. (1) A mixture of inorganic powder and resin, The resin comprises a low melting point component comprising one or more compounds selected from wax, low molecular weight polyethylene, and low molecular weight polypropylene; A flexible component consisting of one or more compounds selected from EVA, elastomer, and polyurethane; and a structure maintaining component selected from polyolefin, polystyrene, PMMA, PLA, PET, phenolic resin, polypropylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyethylene glycol, polyvinyl alcohol, polyamide, polyvinylpyrrolidone, polyacrylate, polyamide, and polycarbonate. (2) The mixture described in (1), wherein the elastomer is a styrene-based elastomer. (3) For 100 vol% of the resin, The low melting point component is 24 to 50 vol% The softening component is 24 to 60 vol% The mixture according to (1) or (2), wherein the structure-maintaining component is present in an amount of 0 to 36 vol %. (4) For 100 vol% of the resin, The low melting point component is 40 to 50 vol% The softening component is 24 to 36 vol% The mixture according to (1) or (2), wherein the structure-maintaining component is 16 to 36 vol %. (5) For 100 vol% of the resin, The low melting point component is 40 to 50 vol% The softening component is 24 to 36 vol% The mixture according to (1) or (2), wherein the structure-maintaining component is 16 to 30 vol %. (6) The mixture according to any one of (1) to (5), wherein the inorganic powder is contained in an amount of 35 to 65 vol% relative to 100 vol% of the mixture. (7) The mixture according to any one of (1) to (5), wherein the inorganic powder is contained in an amount of 40 to 60 vol% relative to 100 vol% of the mixture. (8) The mixture according to any one of (1) to (7), wherein the resin further contains a surfactant. (9) The mixture according to (8), wherein the surfactant is present in an amount of 3 vol% or less relative to 100 vol% of the resin. (10) A filament comprising the mixture according to (1) to (9). (11) A filament for a three-dimensional printer comprising the mixture according to (1) to (9). (12) A molded article produced using the filament according to (10) or (11). (13) a low melting point component consisting of one or more compounds selected from wax, low molecular weight polyethylene, and low molecular weight polypropylene; A flexible component consisting of one or more compounds selected from EVA, elastomer, and polyurethane; and a structure maintaining component selected from polyolefin, polystyrene, PMMA, PLA, PET, phenolic resin, polypropylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyethylene glycol, polyvinyl alcohol, polyamide, polyvinylpyrrolidone, polyacrylate, polyamide, and polycarbonate.

Claims

1. A mixture of inorganic powder and resin, The resin comprises a low melting point component comprising one or more compounds selected from wax, low molecular weight polyethylene, and low molecular weight polypropylene; a flexible component comprising one or more compounds selected from EVA, elastomer, and polyurethane; and a structure maintaining component selected from polyolefin, polystyrene, PMMA, PLA, PET, phenolic resin, polypropylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyethylene glycol, polyvinyl alcohol, polyamide, polyvinylpyrrolidone, polyacrylate, polyamide, and polycarbonate.

2. 2. The mixture of claim 1, wherein the elastomer is a styrenic elastomer.

3. With respect to 100 vol% of the resin, The low melting point component is 24 to 50 vol % The softening component is 24 to 60 vol% 2. The mixture according to claim 1, wherein the structure-maintaining component is 0 to 36 vol.%.

4. With respect to 100 vol% of the resin, The low melting point component is 40 to 50 vol % The softening component is 24 to 36 vol% 2. The mixture according to claim 1, wherein the structure-maintaining component is 16 to 36 vol.%.

5. With respect to 100 vol% of the resin, The low melting point component is 40 to 50 vol % The softening component is 24 to 36 vol% 2. The mixture according to claim 1, wherein the structure-maintaining component is 16 to 30 vol. %.

6. The mixture according to claim 1, wherein the inorganic powder is contained in an amount of 35 to 65 vol% relative to 100 vol% of the mixture.

7. The mixture according to claim 1, wherein the inorganic powder is contained in an amount of 40 to 60 vol% relative to 100 vol% of the mixture.

8. The mixture of claim 1 , wherein the resin further comprises a surfactant.

9. 9. The mixture of claim 8, wherein the surfactant is present in an amount of 3 vol% or less per 100 vol% of the resin.

10. A filament made of a mixture according to claims 1 to 9.

11. A filament for a three-dimensional printer, comprising the mixture according to any one of claims 1 to 9.

12. A molded article produced using the filament according to claim 10.

13. a low melting point component comprising one or more compounds selected from wax, low molecular weight polyethylene, and low molecular weight polypropylene; a flexible component comprising one or more compounds selected from EVA, elastomer, and polyurethane; and a structure maintaining component selected from polyolefin, polystyrene, PMMA, PLA, PET, phenolic resin, polypropylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl butyrate, polyethylene glycol, polyvinyl alcohol, polyamide, polyvinylpyrrolidone, polyacrylate, polyamide, and polycarbonate.

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