Composition for 3D printer filament, filament for 3D printer, sintered body, and method for manufacturing sintered body

Abstract

To provide a filament for a 3D printer that can normally discharge a molten composition from a filament-type 3D printer and form a sintered body with excellent appearance.SOLUTION: A composition for filaments includes a sinterable inorganic powder (A) and an organic binder (B). The organic binder (B) includes: an olefin-based elastomer (B3) selected from a copolymer of an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound, a hydrogenated product thereof, and a copolymer of two or more kinds of unsaturated aliphatic hydrocarbons, the olefin-based elastomer having a predetermined hardness and flow-start temperature; a thermoplastic resin (B1) selected from a non-crystalline polymer other than the above (B3) and EVA; a compound (B5) having a molecular weight of 8000 or less other than the above (B3), the above (B1), and paraffin wax (B4); and a thermoplastic resin (B2) selected from EVA, the above (B3), and a crystalline polymer other than the above (B5), in a predetermined mass ratio.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a filament composition used in a filament-type 3D printer, and also to a filament for a 3D printer using the filament composition, a sintered body, and a method for producing the same. [Background technology]

[0002] 3D printers, which create three-dimensional objects using additive manufacturing based on three-dimensional digital data, are being put to practical use in a variety of fields. The main methods of manufacturing three-dimensional objects using 3D printers are powder bed fusion, binder jetting, material extrusion (MEX), and liquid vat photopolymerization.

[0003] Among these, the material extrusion method is also known as fused deposition modeling (FDM), and is a method for obtaining a three-dimensional object made of thermoplastic resin by melting a material made of thermoplastic resin, layering the molten resin one layer at a time, and then cooling and solidifying it. This method is becoming increasingly widespread because the equipment used is simple.

[0004] When manufacturing three-dimensional objects made of metal or ceramics using a 3D printer, the powder bed fusion method, which uses a high-power laser to directly sinter the object, and the liquid tank photopolymerization method, which disperses a filler in a photocurable resin, are generally used. However, these methods have problems such as the high cost of the equipment and the slow layering speed.

[0005] In response to this, Patent Document 1 discloses a technique for manufacturing metal products or ceramic products at low cost and at high speed using a material extrusion method. Specifically, for example, Patent Document 1 produces pellets from a thermoplastic resin containing metal powder, forms a shaped object from the pellets using a material extrusion method, heats the shaped object under specified conditions to degrease it, and finally sinters the metal powder in the shaped object to manufacture a metal product.

[0006] Filament-type 3D printers are known that use filaments instead of pellets to manufacture objects. Filament-type 3D printers generally use filaments wound in a roll with a diameter of 1.75 mm or the like. Filament-type 3D printers have a gear section that sends the filament sandwiched between the gears to the heater section by the rotation of the gears. In filament-type 3D printers, the gear section sends the filament to the heater section where it is melted, and the filament is layered into a specified shape as it is discharged from the tip of the nozzle. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2020 / 003901 issue Summary of the Invention [Problem to be solved by the invention]

[0008] If filament-type 3D printers like those described above could be used to model metals and ceramics, it would solve problems such as equipment costs and building speed that arise when using methods such as powder bed fusion, and it would also make it possible to produce metal and ceramic products using inexpensive 3D printers, which are becoming increasingly popular.

[0009] However, when the composition for 3D printers disclosed in Patent Document 1 is made into a filament having a diameter of, for example, 1.75 mm, it is brittle and easily breaks, making it difficult to wind it into a roll. Even if a plasticizer or the like is added to the filament to give it flexibility, the filament buckles, breaks, or is scraped around the gear portion, causing problems such as the filament being unable to be fed normally.

[0010] In addition, filaments used in shaping metals and ceramics are required to be able to be shaped into the desired shapes, just like filaments used in ordinary resin shaping, and also to have an excellent appearance when the sintered body is obtained after debinding and sintering.

[0011] An object of the present invention is to provide a composition for a 3D printer filament, which is capable of normally discharging a molten composition from a filament-type 3D printer and forming a sintered body with excellent appearance, and a 3D printer filament using the composition. Another object of the present invention is to provide a sintered body obtained by using the 3D printer filament, and a method for producing the sintered body. [Means for solving the problem]

[0012] The present invention includes the embodiments set forth below. [1] A composition for filaments used in a filament-type 3D printer, comprising a sinterable inorganic powder (A) and an organic binder (B), wherein the organic binder (B) is at least one olefin-based elastomer selected from the group consisting of copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, hydrogenated copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, and copolymers of two or more kinds of unsaturated aliphatic hydrocarbons, the olefin-based elastomer (B3) having a hardness of A60 or more and a flow-initiation temperature of 130°C or more, at least one thermoplastic resin (B1) selected from the group consisting of amorphous polymers other than the olefin-based elastomer (B3) and EVA, a compound (B5) having a weight-average molecular weight of 8000 or less, excluding the olefin-based elastomer (B3), the thermoplastic resin (B1), and paraffin wax (B4), and and a thermoplastic resin (B2) selected from crystalline polymers other than the EVA, the olefin-based elastomer (B3), and the compound (B5), the amount of the organic binder (B) is 5 to 55 parts by mass with respect to 100 parts by mass of the sinterable inorganic powder (A), and the mass ratio (((B1)+(B5)) / (B)) of the total of the thermoplastic resin (B1) and the compound (B5) to the organic binder (B) is 0.10 to 0.60. a mass ratio ((B2) / (B)) of the thermoplastic resin (B2) to the organic binder (B) is 0.05 to 0.80, a mass ratio ((B3) / (B)) of the olefin-based elastomer (B3) to the organic binder (B) is 0.03 to 0.60, and a mass ratio ((B5) / (B)) of the compound (B5) to the organic binder (B) is 0.02 to 0.20.

[0013] [2] The composition for 3D printer filaments described in [1], wherein the thermoplastic resin (B1) includes at least one selected from the group consisting of (meth)acrylic acid ester polymers and EVA.

[0014] [3] The composition for 3D printer filaments described in [1] or [2], wherein the thermoplastic resin (B2) includes at least one selected from the group consisting of polyacetal, polyethylene, and polypropylene.

[0015] [4] The composition for 3D printer filaments according to any one of [1] to [3], wherein the compound (B5) includes at least one selected from the group consisting of fatty acids, fatty acid esters, fatty acid amides, fatty acid salts, diesters having a carbon ring, phosphate esters, and phenol compounds.

[0016] [5] The composition for 3D printer filaments according to any one of [1] to [4], wherein the mass ratio ((B4) / (B)) of the paraffin wax (B4) to the organic binder (B) is 0.25 or less.

[0017] [6] The composition for 3D printer filaments according to any one of [1] to [5], wherein the olefin-based elastomer (B3) comprises a hydrogenated product of a block copolymer of styrene and butadiene, and / or an acid-modified ethylene-α-olefin copolymer.

[0018] [7] A 3D printer filament produced using the filament composition described in any one of [1] to [6].

[0019] [8] A sintered body of the sinterable inorganic powder (A) produced using the 3D printer filament described in [7].

[0020] [9] A method for producing a sintered body of a sintered inorganic powder (A), comprising the steps of: forming a laminated structure by a fused deposition model filament-type 3D printer using the 3D printer filament described in [7]; degreasing the formed laminated structure; and sintering the sinterable inorganic powder (A) in the degreased laminated structure. Effect of the Invention

[0021] According to an embodiment of the present invention, it is possible to provide a composition for a 3D printer filament, which can normally discharge a molten composition from a filament-type 3D printer and form a sintered body with excellent appearance, and a 3D printer filament using the same. In addition, according to the present invention, it is also possible to provide a sintered body obtained by using the 3D printer filament and a method for producing the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The composition for the filament of the 3D printer according to this embodiment contains a sinterable inorganic powder (A) and an organic binder (B). As the 3D printer, for example, one that can mold a three-dimensional structure by heating and fluidizing a 3D printer filament and discharging it from a nozzle and laminating it can be used, and various filament-type 3D printers using material extrusion deposition modeling (MEX) (fused deposition modeling: FDM) can be used. In this specification, a molded object formed by laminating a composition using a 3D printer is also referred to as a "laminated structure", and a molded object obtained by sintering the sinterable inorganic powder (A) in the laminated structure is also referred to as a "sintered body".

[0023] <Sinterable inorganic powder (A)> The sinterable inorganic powder (A) is an inorganic powder that has the property of being sintered, for example, by heating to a high temperature. Examples of the sinterable inorganic powder (A) include metal powders, ceramic powders, and cermet powders. Specific examples of metal powders include powders of pure iron, iron-nickel, iron-cobalt, iron-silicon, iron-based alloys such as stainless steel (stainless steel), tungsten, aluminum alloys, copper, copper alloys, cemented carbide (WC-Co-based alloys, etc.), titanium, and titanium alloys. Specific examples of ceramic powders include powders of oxides such as Al2O3, BeO, ZrO2, and SiO2, carbides such as TiC, ZrC, B4C, tungsten carbide (WC), and silicon carbide (SiC), borides such as CrB and ZrB2, and nitrides such as titanium nitride, zirconium nitride, boron nitride, and aluminum nitride (AlN). Specific examples of the cermet powder include Al2O3-Fe-based, TiC-Ni-based, TiC-Co-based, B4C-Fe-based powders, etc. These may be used alone or in combination of two or more.

[0024] The average particle size of the sinterable inorganic powder (A) is not particularly limited, and may be, for example, 0.05 to 100 μm, 0.05 to 30 μm, or 0.1 to 10 μm. The average particle size may be 0.05 to 3 μm, 0.1 to 2 μm, or 0.1 to 1 μm. The average particle size may be 0.5 to 10 μm, 1.0 to 9 μm, or 1.0 to 8 μm.

[0025] In this specification, the average particle size of the sinterable inorganic powder (A) means the particle size (D50) at an integrated value of 50% in the particle size distribution determined by a laser diffraction / scattering method (Microtrac particle size measuring device: MT3100II).

[0026] <Organic binder (B)> The organic binder (B) according to this embodiment is At least one olefin-based elastomer selected from the group consisting of copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, hydrogenated copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, and copolymers of two or more kinds of unsaturated aliphatic hydrocarbons, the olefin-based elastomer having a hardness of A60 or more and a flow-initiation temperature of 130°C or more (B3); At least one thermoplastic resin (B1) selected from the group consisting of non-crystalline polymers other than olefin-based elastomers (B3) and EVA, Compounds (B5) having a weight average molecular weight of 8000 or less, other than olefin-based elastomers (B3), thermoplastic resins (B1), and paraffin wax (B4), and A thermoplastic resin (B2) selected from crystalline polymers excluding EVA, olefin-based elastomers (B3) and compounds (B5).

[0027] <Olefin elastomer (B3)> The olefin elastomer is a polymer containing an unsaturated aliphatic hydrocarbon having a carbon-carbon double bond as a constituent monomer, and is a thermoplastic elastomer having rubber elasticity at room temperature (25°C). In this embodiment, as the olefin elastomer (B3), at least one selected from the group consisting of a copolymer of an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound (hereinafter sometimes referred to as "aromatic copolymer (B31)"), a hydrogenated copolymer of an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound (B32), and a copolymer of two or more kinds of unsaturated aliphatic hydrocarbons (hereinafter sometimes referred to as "aliphatic copolymer (B33)") is used. These aromatic copolymers (B31), hydrogenated copolymers (32), and aliphatic copolymers (B33) may be either acid-modified or not acid-modified.

[0028] The unsaturated aliphatic hydrocarbon constituting the olefin elastomer (B3) preferably has 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms. The number of carbon-carbon double bonds in the unsaturated aliphatic hydrocarbon is preferably 1 or 2. The unsaturated aliphatic hydrocarbon preferably does not have a triple bond. Specific examples of the unsaturated aliphatic hydrocarbon include monoolefins such as ethylene, propylene, and butylene, and diolefins such as butadiene and isoprene.

[0029] Examples of aromatic vinyl compounds constituting the aromatic copolymer (B31) and the hydrogenated product (B32) include styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, etc. In the aromatic copolymer (B31) and the hydrogenated product (B32), the content of the structural unit derived from the aromatic vinyl compound is not particularly limited and may be, for example, 10 to 50 mass%, 10 to 35 mass%, or 12 to 30 mass%.

[0030] The aromatic vinyl compound is preferably styrene. Therefore, the aromatic copolymer (B31) is preferably a copolymer of an unsaturated aliphatic hydrocarbon and styrene, and the hydrogenated product (B32) is preferably a hydrogenated product of a copolymer of an unsaturated aliphatic hydrocarbon and styrene.

[0031] Specific examples of the aromatic copolymer (B31) include a copolymer of styrene and butadiene, a copolymer of styrene, ethylene and propylene, and a copolymer of styrene, ethylene and butylene. Any one of these may be used alone or in combination of two or more.

[0032] The aromatic copolymer (B31) may be a random copolymer or a block copolymer, but is preferably a block copolymer. The block copolymer of styrene and butadiene is preferably a copolymer in which each monomer is block-added in the order of styrene-butadiene-styrene. The block copolymer of styrene, ethylene, and propylene is preferably a copolymer in which each monomer is block-added in the order of styrene-ethylene-propylene-styrene. The block copolymer of styrene, ethylene, and butylene is preferably a copolymer in which each monomer is block-added in the order of styrene-ethylene-butylene-styrene.

[0033] The hydrogenated product (B32) is a copolymer of an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound in which hydrogen has been added to the carbon-carbon double bond of a structural unit derived from an unsaturated aliphatic hydrocarbon, and examples of such a compound include compounds obtained by adding hydrogen to the aromatic copolymer (B31). The hydrogenation rate of the double bond in the structural unit derived from an unsaturated aliphatic hydrocarbon is not particularly limited, and may be, for example, 50% or more, 80% or more, or 90% or more. The hydrogenation rate may be, for example, 1 It can be measured by H-NMR.

[0034] The aliphatic copolymer (B33) is a copolymer of two or more kinds of unsaturated aliphatic hydrocarbons, and is preferably a copolymer of two or more kinds of the above-mentioned unsaturated aliphatic hydrocarbons having 2 to 6 carbon atoms (more preferably 2 to 4 carbon atoms). The aliphatic copolymer (B33) may be a random copolymer or a block copolymer, so long as it is an elastomer. Specific examples of the aliphatic copolymer (B33) include ethylene-propylene copolymer, ethylene-butylene copolymer, ethylene-propylene-butylene copolymer, and propylene-butylene copolymer, and preferably ethylene-α-olefin copolymers such as copolymers of ethylene and propylene and copolymers of ethylene and 1-butene.

[0035] The aromatic copolymer (B31), the hydrogenated product (32) and the aliphatic copolymer (B33) may be acid-modified as described above. The acid-modified aromatic copolymer (B31), the hydrogenated product (32) and the aliphatic copolymer (B33) have an acid anhydride group and / or a carboxy group as a modifying group.

[0036] For example, the acid-modified aromatic copolymer (B31) may be one obtained by copolymerizing an unsaturated compound having an acid anhydride group and / or a carboxy group (e.g., a dibasic acid such as maleic anhydride) together with an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound, or may be one obtained by graft-modifying a copolymer of an unsaturated aliphatic hydrocarbon and an aromatic vinyl compound with an unsaturated compound having an acid anhydride group and / or a carboxy group under radical reaction conditions.

[0037] The acid-modified hydrogenated product (B32) may be a product obtained by hydrogenating the acid-modified aromatic copolymer (B31), or may be a product obtained by introducing a modifying group by graft modification after hydrogenation.

[0038] The acid-modified aliphatic copolymer (B33) may be one obtained by copolymerizing an unsaturated compound having an acid anhydride group and / or a carboxy group with two or more kinds of unsaturated aliphatic hydrocarbons, or may be one obtained by graft-modifying a copolymer of two or more kinds of unsaturated aliphatic hydrocarbons with an unsaturated compound having an acid anhydride group and / or a carboxy group under radical reaction conditions.

[0039] The degree of modification by acid modification is not particularly limited, and may be, for example, 0.1 to 4.0 mass %, or 0.5 to 3.0 mass %. Here, the degree of modification is measured based on the wave number of 1780 cm assigned to the carbonyl group in FT-IR. -1 It can be determined based on the peak intensity.

[0040] The weight average molecular weight of the aromatic copolymer (B31), the hydrogenated product (B32) and the aliphatic copolymer (B33) is not particularly limited, and is preferably, for example, from 30,000 to 300,000.

[0041] In one embodiment, the olefin elastomer (B3) is preferably a hydrogenated copolymer of an unsaturated aliphatic hydrocarbon and styrene, and / or an acid-modified copolymer of two or more kinds of unsaturated aliphatic hydrocarbons, and more preferably a hydrogenated block copolymer of styrene and butadiene, and / or an acid-modified ethylene-α-olefin copolymer.

[0042] In one embodiment, 100% by mass of the olefin-based elastomer (B3) preferably contains 50% by mass or more (more preferably 70% by mass or more, even more preferably 80% by mass or more, or may be 100% by mass) of the hydrogenated product (B32) and / or the aliphatic copolymer (B33), more preferably contains 50% by mass or more (more preferably 70% by mass or more) of the hydrogenated product (B32) (even more preferably a hydrogenated product of a copolymer of an unsaturated aliphatic hydrocarbon and styrene). More preferably, 100% by mass of the olefin-based elastomer (B3) contains 50% by mass or more (more preferably 70% by mass or more, even more preferably 80% by mass or more, or may be 100% by mass) of a hydrogenated product of a block copolymer of styrene and butadiene and / or an acid-modified ethylene-α-olefin copolymer, and even more preferably contains 50% by mass or more (more preferably 70% by mass or more) of a hydrogenated product of a block copolymer of styrene and butadiene.

[0043] The olefin-based elastomer (B3) has a hardness of A60 or more (i.e., A60 or harder than A60) and a flow initiation temperature of 130° C. or more. By using an olefin-based elastomer (B3) having a high hardness in this way, even if the amount of the thermoplastic resin (B2), which is a crystalline polymer, is reduced, the rigidity of the filament is increased, buckling or breaking around the gear part is prevented, and the feeding stability of the filament can be improved. Therefore, by reducing the amount of the thermoplastic resin (B2) without impairing the feeding stability of the filament, the adhesion between layers in the laminate structure can be improved, and poor adhesion in a relatively large laminate structure can be improved.

[0044] The hardness of the olefin elastomer (B3) is more preferably A65 or more. The upper limit of the hardness of the olefin elastomer (B3) is preferably D80 or less, more preferably D60 or less. The hardness of the olefin elastomer (B3) is more preferably A65 or more and A95 or less, and even more preferably A65 or more and A90 or less.

[0045] In this specification, the hardness of the olefin-based elastomer (B3) is measured in accordance with ISO 7619, and the "A" before the numerical value means the hardness of type A according to ISO 7619, and the "D" before the numerical value means the hardness of type D according to ISO 7619. When the hardness according to type A exceeds 95 (i.e., A95), it is measured according to type D.

[0046] The upper limit of the flow temperature of the olefin-based elastomer (B3) is not particularly limited, but is preferably 230° C. or lower. The flow temperature of the olefin-based elastomer (B3) is more preferably 130° C. or higher and 200° C. or lower, and even more preferably 132° C. or higher and 180° C. or lower.

[0047] In this specification, the "flow initiation temperature" is defined as follows: the temperature at which a molten sample begins to flow out of a die when the temperature of the sample is increased from 25°C at a rate of 5°C / min under the conditions of a die hole diameter of 1.0 mm, a die hole length of 1.0 mm, and a load on the sample of 0.98 MPa. The flow initiation temperature can be measured, for example, using a constant test force extrusion capillary rheometer flow tester "CFD-500D" manufactured by Shimadzu Corporation.

[0048] <Thermoplastic resin (B1)> As described above, the organic binder (B) according to this embodiment contains at least one thermoplastic resin (B1) selected from the group consisting of the amorphous polymer (B11) excluding the olefin-based elastomer (B3) and EVA (ethylene-vinyl acetate copolymer) (B12). In other words, the organic binder (B) contains a thermoplastic resin (B1), which is at least one of the amorphous polymer (B11) and EVA (B12), but the amorphous polymer (B11) does not contain the olefin-based elastomer (B3).

[0049] Examples of the non-crystalline polymer (B11) include polymers of (meth)acrylic acid esters, that is, polymers containing (meth)acrylic acid esters as constituent monomers. Examples of the polymers of (meth)acrylic acid esters include polymers of esters of alcohols having 1 to 8 carbon atoms and (meth)acrylic acid. Examples of the (meth)acrylic acid esters constituting such polymers include n-alkyl (meth)acrylates having an alkyl group having 1 to 8 carbon atoms, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and glycidyl (meth)acrylate. Any one of these may be used, or two or more may be used in combination.

[0050] Here, "(meth)acrylate" refers to acrylate or methacrylate, and "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. A polymer of a (meth)acrylic acid ester is also called an "acrylic resin."

[0051] The (meth)acrylic acid ester polymer may be a copolymer of two or more (meth)acrylic acid esters, or a copolymer of a (meth)acrylic acid ester and another monomer. Examples of such copolymers include a copolymer of methyl methacrylate and butyl acrylate, a copolymer of ethylene and glycidyl methacrylate, and a copolymer of ethylene, glycidyl methacrylate, and styrene.

[0052] The (meth)acrylic acid ester polymer may be a random copolymer or a block copolymer, but a block copolymer is preferred. The copolymer of methyl methacrylate and butyl acrylate is preferably a polymer in which methyl methacrylate-butyl acrylate-methyl methacrylate are block-added in this order (for example, "Clarity LA2140" manufactured by Kuraray Co., Ltd.). The butyl group in the butyl acrylate is preferably an n-butyl group. Any one of these may be used, or two or more may be used in combination.

[0053] The weight average molecular weight of the non-crystalline polymer (B11) is not particularly limited and may be, for example, 10,000 or more, 20,000 or more, 40,000 or more, and may be 400,000 or less, or 300,000 or less.

[0054] EVA is a copolymer of ethylene and vinyl acetate. It is more preferable to use EVA with low crystallinity (for example, with a crystallinity of 25% or less). Since the crystallinity of EVA correlates with the vinyl acetate (VA) content, a preferable EVA is, for example, EVA with a vinyl acetate content (mass percentage: JIS K7192:1999) of 20% to 50%, more preferably 25% to 40%. In addition, it is preferable to use EVA with a weight average molecular weight of about 30,000 to 120,000, more preferably about 50,000 to 100,000. Any one of these may be used, or two or more may be used in combination.

[0055] As the thermoplastic resin (B1), at least one selected from the group consisting of acrylic resins and EVA is particularly preferred. As the acrylic resin, a polymer of n-butyl methacrylate, a copolymer of methyl methacrylate and n-butyl acrylate, a copolymer of ethylene and glycidyl methacrylate, a copolymer of n-butyl methacrylate and acrylic acid, a copolymer of ethylene and glycidyl methacrylate, and a copolymer of ethylene, glycidyl methacrylate and styrene are preferred. Any one of these may be used, or two or more may be used in combination.

[0056] In one embodiment, 100% by mass of the thermoplastic resin (B1) preferably contains 50% by mass or more (more preferably 70% by mass or more, even more preferably 80% by mass or more, or it may be 100% by mass) of an acrylic resin and / or EVA, and preferably contains 50% by mass or more (more preferably 70% by mass or more) of an acrylic resin.

[0057] <Compound (B5)> As described above, the organic binder (B) according to this embodiment contains a compound (B5) having a weight average molecular weight of 8000 or less, excluding the olefin-based elastomer (B3), the thermoplastic resin (B1), and the paraffin wax (B4). In other words, the organic binder (B) contains a compound (B5) having a weight average molecular weight of 8000 or less, but this compound (B5) does not contain the olefin-based elastomer (B3), the thermoplastic resin (B1), or the paraffin wax (B4).

[0058] The compound (B5) is not particularly limited, and includes at least one (B51) selected from the group consisting of fatty acids, fatty acid esters, fatty acid amides, fatty acid salts, phosphate esters, phenolic compounds, and diesters having a carbon ring. In one embodiment, 100% by mass of the compound (B5) preferably includes 60% by mass or more (more preferably 80% by mass or more, or may be 100% by mass) of the at least one (B51).

[0059] In this specification, the weight average molecular weight can be determined, for example, by using gel permeation chromatography (GPC).

[0060] The weight average molecular weight of the compound (B5) is not particularly limited as long as it is 8000 or less, but is preferably 5000 or less, more preferably 3000 or less, more preferably 2000 or less, more preferably 1000 or less, more preferably 800 or less, more preferably 700 or less, and even more preferably 600 or less. In addition, the weight average molecular weight is preferably 32 or more, more preferably 75 or more, more preferably 100 or more, and even more preferably 200 or more.

[0061] When the compound (B5) is a compound having no molecular weight distribution, the "weight average molecular weight" simply means the molecular weight.

[0062] The fatty acid may be, for example, a higher fatty acid having more than 10 carbon atoms. Of these, fatty acids having 15 to 25 carbon atoms are preferred, and fatty acids having 16 to 20 carbon atoms are more preferred. Furthermore, as the fatty acid, saturated fatty acids are preferred over unsaturated fatty acids. As the fatty acid, stearic acid, which is a saturated fatty acid having 18 carbon atoms, is the most preferred. Any one of these may be used, or two or more may be used in combination.

[0063] The fatty acid ester may be, for example, an ester of a polyfunctional alcohol and a higher fatty acid. The polyfunctional alcohol may be, for example, sucrose, ethylene glycol, propylene glycol, diethylene glycol, and sorbitan, and among these, sorbitan is most preferred. The fatty acid ester is preferably a monoester. The fatty acid constituting the fatty acid ester is preferably a fatty acid having 15 to 25 carbon atoms, and more preferably a fatty acid having 16 to 20 carbon atoms. The fatty acid constituting the fatty acid ester is preferably a saturated fatty acid rather than an unsaturated fatty acid. The fatty acid ester is most preferably a monostearate sorbitan ester. Any one of these may be used, or two or more may be used in combination.

[0064] Examples of the fatty acid amide include those obtained by dehydration condensation of ammonia, primary amine, or secondary amine with higher fatty acid. The fatty acid constituting the fatty acid amide is preferably a fatty acid having 15 to 25 carbon atoms, more preferably a fatty acid having 16 to 20 carbon atoms. Examples of the primary amine or secondary amine include aromatic amine, aliphatic amine, and alicyclic amine. Any one of these may be used, or two or more may be used in combination.

[0065] The fatty acid salts include metal salts of the fatty acids as described above. Specifically, alkali metal salts such as sodium salts, potassium salts, and lithium salts can be mentioned. Any one of these may be used, or two or more may be used in combination.

[0066] The above phosphoric acid ester is preferably, for example, a halogenated phosphoric acid ester, and more preferably, a chlorinated phosphoric acid ester. Examples of the phosphoric acid ester include tris(chloroethyl)phosphate, tris(β-chloropropyl)phosphate, tris(dichloropropyl)phosphate, tetrakis(2-chloroethyl)dichloroisopentyl diphosphate, and polyoxyalkylene bis(dichloroalkyl)phosphate. Any one of these may be used, or two or more may be used in combination.

[0067] Examples of the phenolic compounds include 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-butylidenebis(6-tert-butyl-m-cresol), bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)], bis[3-(3-tert-butyl-4-hydroxy-5-methylphenylpropionic acid)(2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diyl)bis(2,2-dimethyl-2,1-ethanediyl), and pentaerythritol=tetrakis[3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)]propionate]. Any one of these may be used, or two or more may be used in combination.

[0068] Examples of the diester having a carbon ring include a diester of an aliphatic alcohol and a dicarboxylic acid having a carbon ring. The aliphatic alcohol is preferably an aliphatic alcohol having 3 to 10 carbon atoms, more preferably an aliphatic alcohol having 4 to 8 carbon atoms. Specific examples of the diester having a carbon ring include phthalates such as dibutyl phthalate and dioctyl phthalate, 4-cyclohexene-1,2-dicarboxylate bis(2-ethylhexyl), and 1,2-cyclohexanedicarboxylate diisononyl ester. Any one of these may be used, or two or more may be used in combination.

[0069] <Thermoplastic resin (B2)> As described above, the organic binder (B) according to this embodiment contains a thermoplastic resin (B2) selected from crystalline polymers excluding EVA, olefin-based elastomer (B3), and compound (B5). In other words, the organic binder (B) contains a thermoplastic resin (B2) that is a crystalline polymer, but this thermoplastic resin (B2) does not contain EVA, olefin-based elastomer (B3), or compound (B5).

[0070] The weight average molecular weight of the crystalline polymer is not particularly limited, and may be, for example, 10,000 or more, 20,000 or more, or 40,000 or more, and may be 400,000 or less, or 300,000 or less.

[0071] Examples of the thermoplastic resin (B2) include polyacetal (POM), polyethylene (PE), polypropylene (PP), polybutene, polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and polylactic acid (PLA). Any one of these may be used, or two or more may be used in combination. The thermoplastic resin (B2) preferably contains at least one thermoplastic resin (B21) selected from the group consisting of polyacetal (POM), polyethylene (PE), and polypropylene (PP).

[0072] Polyacetal is a polymer having an oxymethylene unit (-CH2O-) as a constituent unit, and examples thereof include polyacetal homopolymer and polyacetal copolymer. Polyacetal homopolymer is a polymer having only oxymethylene units in the main chain. Polyacetal copolymer is a copolymer having an oxymethylene unit derived from a main monomer and a comonomer unit derived from a comonomer in the main chain. The comonomer unit is not particularly limited as long as it can be copolymerized with the oxymethylene unit, and examples of the comonomer unit include oxyalkylene units having 2 or more carbon atoms, such as oxyethylene units, oxypropylene units, and oxybutylene units. The content ratio of the comonomer unit in the polyacetal copolymer is not particularly limited, and may be, for example, 0.01 to 10 mol%, or 0.1 to 5 mol%. The weight average molecular weight of the polyacetal is not particularly limited, and may be, for example, 10,000 to 200,000, or 20,000 to 100,000.

[0073] The polyethylene and polypropylene are not particularly limited, and for example, those having a weight average molecular weight of about 100,000 to 400,000 are preferably used, and those having a weight average molecular weight of about 200,000 to 300,000 are more preferably used.

[0074] In one embodiment, 100% by mass of the thermoplastic resin (B2) preferably contains 50% by mass or more of the thermoplastic resin (B21), more preferably 70% by mass or more, and even more preferably 80% by mass or more, and may be 100% by mass.

[0075] In one embodiment, the thermoplastic resin (B2) preferably contains polyacetal as a main component. That is, the amount of polyacetal in 100% by mass of the thermoplastic resin (B2) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and may be 100% by mass. The thermoplastic resin (B2) may contain 70 to 100% by mass of polyacetal and 0 to 30% by mass of polyethylene and / or polypropylene, or may contain 80 to 100% by mass of polyacetal and 0 to 20% by mass of polyethylene and / or polypropylene.

[0076] <Paraffin wax (B4)> The organic binder (B) according to this embodiment may or may not further contain paraffin wax (B4). By containing paraffin wax (B4), the fluidity of the filament composition or the 3D printer filament during heating can be improved. Note that paraffin wax (B4) does not fall under the above (B1) to (B3).

[0077] For example, when the average particle size of the sinterable inorganic powder (A) is small, the 3D printer filament is less likely to soften due to heat due to the large surface area of ​​the sinterable inorganic powder (A). Here, adding paraffin wax (B4) to the organic binder (B) improves the fluidity when heated, and improves the ejection stability from the nozzle.

[0078] The paraffin wax (B4) is not particularly limited, and for example, one having a melting point of 60° C. or higher is preferable, and one having a melting point of 65 to 80° C. is more preferable. The melting point is measured in accordance with JIS K2235:1991.

[0079] In the filament composition according to this embodiment, the organic binder (B) may contain additives such as waxes other than the paraffin wax (B4), plasticizers, antioxidants, metal deactivators, ultraviolet absorbers, lubricants, and nucleating agents, within the range that does not impair the effects of the present invention.

[0080] In the composition for filaments according to this embodiment, the amount of the organic binder (B) is 5 to 55 parts by mass relative to 100 parts by mass of the sinterable inorganic powder (A). By having the amount of the organic binder (B) be 5 parts by mass or more, the flow value of the composition for filaments is increased, making it easier to mold, and the filament is less likely to break. By having the amount of the organic binder (B) be 55 parts by mass or less, defects such as buckling of the filament at the gear part of the filament-type 3D printer are less likely to occur, and deformation of the laminated structure during degreasing can be suppressed. The amount of the organic binder (B) is preferably 6 to 25 parts by mass relative to 100 parts by mass of the sinterable inorganic powder (A). Note that "buckling" is likely to occur when the filament is too soft, so the filament needs to have a certain degree of hardness.

[0081] When the sinterable inorganic powder (A) is a metal powder (e.g., stainless steel, cemented carbide, etc.), the amount of the organic binder (B) is preferably 5 to 18 parts by mass, more preferably 5 to 15 parts by mass, per 100 parts by mass of the sinterable inorganic powder (A), from the viewpoints of suppressing defects during use of the filament and improving the appearance of the laminated structure.

[0082] When the sinterable inorganic powder (A) is a ceramic powder (e.g., a metal oxide powder such as alumina or zirconia), from the viewpoints of suppressing defects during use of the filament and improving the appearance of the laminated structure, the organic binder (B) is preferably 15 to 55 parts by mass, more preferably 20 to 40 parts by mass, per 100 parts by mass of the sinterable inorganic powder (A).

[0083] When the sinterable inorganic powder (A) is a cermet powder (e.g., a TiC-Co-based powder, etc.), from the viewpoints of suppressing defects during use of the filament and improving the appearance of the laminated structure, the organic binder (B) is preferably 5 to 15 parts by mass, more preferably 5 to 10 parts by mass, per 100 parts by mass of the sinterable inorganic powder (A).

[0084] In the composition for filaments according to the present embodiment, the mass ratio (((B1)+(B5)) / (B)) of the total of the thermoplastic resin (B1) and the compound (B5) to the organic binder (B) is 0.10 to 0.60. When the mass ratio is 0.10 or more, the lamination property is improved and the relative density of the sintered body can be increased. When the mass ratio is 0.60 or less, cracks due to the pressing of the gear are unlikely to occur and the filament is unlikely to break. The mass ratio is preferably 0.15 to 0.54, more preferably 0.17 to 0.50, more preferably 0.18 to 0.45, and even more preferably 0.20 to 0.40.

[0085] In the composition for filaments according to the present embodiment, the mass ratio ((B2) / (B)) of the thermoplastic resin (B2) to the organic binder (B) is 0.05 to 0.80. When the mass ratio is 0.05 or more, the hardness of the filament can be increased to suppress the occurrence of cracks due to the pressing of the gear. When the mass ratio is 0.80 or less, the occurrence of defects around the gear can be suppressed. Furthermore, the smaller the mass ratio, the more the adhesion between the layers in the laminated structure can be improved, and the occurrence of cracks between layers can be suppressed, particularly when a ceramic powder is used as the sinterable inorganic powder (A). The mass ratio is preferably 0.05 to 0.65, more preferably 0.05 to 0.60, more preferably 0.05 to 0.55, more preferably 0.06 to 0.45, and even more preferably 0.07 to 0.40.

[0086] In the composition for filaments according to the present embodiment, the mass ratio ((B3) / (B)) of the olefin-based elastomer (B3) to the organic binder (B) is 0.03 to 0.60. The olefin-based elastomer (B3) contributes to flexibility, elongation, and adhesiveness. Therefore, when the mass ratio is 0.03 or more, flexibility can be imparted to the filament, making it less likely to break, and lamination properties can be improved. When the mass ratio is 0.60 or less, the occurrence of defects around the gear part can be suppressed. The mass ratio is preferably 0.03 to 0.55, more preferably 0.05 to 0.50, more preferably 0.06 to 0.30, and even more preferably 0.07 to 0.13.

[0087] In the composition for filaments according to this embodiment, the mass ratio ((B5) / (B)) of the compound (B5) to the organic binder (B) is 0.02 to 0.20. When the mass ratio is 0.02 or more, the filament is less likely to break, and the relative density of the sintered body can be increased. When the mass ratio is 0.20 or less, the ejection stability from the nozzle is improved, and deformation of the laminated structure during degreasing can be suppressed. The mass ratio is preferably 0.03 to 0.15, more preferably 0.03 to 0.10, and even more preferably 0.03 to 0.08.

[0088] In the composition for filaments according to this embodiment, the mass ratio ((B4) / (B)) of the paraffin wax (B4) to the organic binder (B) is preferably 0.25 or less. By making the mass ratio 0.25 or less, it is possible to suppress softening of the filament due to heat in the gear portion. Since the paraffin wax (B4) is an optional component, the mass ratio may be 0. The mass ratio is preferably 0 to 0.23, more preferably 0 to 0.20, and even more preferably 0 to 0.18.

[0089] In the filament composition according to this embodiment, the mass ratio ((B1) / (B)) of the thermoplastic resin (B1) to the organic binder (B) is not particularly limited, but is preferably 0.08 to 0.55, more preferably 0.10 to 0.45, more preferably 0.15 to 0.40, and even more preferably 0.18 to 0.35.

[0090] In the filament composition according to this embodiment, the mass ratio of the thermoplastic resin (B2) to the thermoplastic resin (B1) ((B2) / (B1)) is not particularly limited, but is preferably 0.60 to 8.0, more preferably 1.0 to 5.0, and even more preferably 1.5 to 3.5.

[0091] In the composition for filaments according to this embodiment, the mass ratio ((B3) / (B1)) of the olefin-based elastomer (B3) to the thermoplastic resin (B1) is not particularly limited, but is preferably 0.05 to 6.0, more preferably 0.10 to 2.0, more preferably 0.15 to 1.20, and even more preferably 0.20 to 0.85.

[0092] In the composition for filaments according to this embodiment, the mass ratio of the compound (B5) to the thermoplastic resin (B1) ((B5) / (B1)) is not particularly limited, but is preferably 0.05 to 1.0, more preferably 0.08 to 0.50, and even more preferably 0.10 to 0.40.

[0093] The flow value of the filament composition according to this embodiment at 200° C., measured in accordance with JIS (1999 edition) K7210 Appendix C, is 0.001 to 0.150 cm 3 / sec. at 200°C. 3 The flow rate at 200°C is 0.150 cm / sec or more, which makes it easy to mold laminated structures. 3By setting the flow value at 200° C. to 0.005 to 0.100 cm / sec or less, stringiness during molding of the laminated structure can be suppressed, and deformation of the laminated structure can be suppressed. 3 / sec, and more preferably 0.008 to 0.050 cm 3 / sec.

[0094] The flow value can be measured, for example, using a constant test force extrusion type capillary rheometer flow tester "CFD-500D" manufactured by Shimadzu Corporation. More specifically, the flow value is determined at a measurement temperature of 200°C under the conditions of a die hole diameter of 1.0 mm, a die hole length of 1.0 mm, and a load on the sample of 0.98 MPa.

[0095] Stringiness is a phenomenon that occurs when a layered structure is created using a 3D printer. For example, after the creation of the first layer has been completed, the nozzle is moved to start creating the next layer, and the resin forms strings between the layered structure being created and the nozzle. When this occurs, the appearance of the layered structure deteriorates.

[0096] The flow-start temperature of the composition for filaments according to this embodiment is preferably 84 to 189°C, more preferably 120 to 180°C. When the flow-start temperature is 84°C or higher, the filaments are prevented from being softened by heat in the gear section, and buckling defects are less likely to occur. When the flow-start temperature is 189°C or lower, the filaments tend to dissolve normally in the heater section. Here, the definition of "flow-start temperature" and the method of measuring it are as described above for the olefin-based elastomer (B3).

[0097] The composition for filaments according to this embodiment may contain crosslinked polymer particles in addition to the sinterable inorganic powder (A) and the organic binder (B). By containing the crosslinked polymer particles, the sintered body becomes a porous body, and a porous ceramic body or a porous metal body can be obtained.

[0098] The filament for the filament-type 3D printer according to the present embodiment can be produced by a conventional method using the above-mentioned composition for filament. Specifically, for example, the composition for filament is melted at a temperature of 90 to 250°C, extruded from a nozzle hole by a constant-volume feeder, cooled and solidified in a liquid bath at 20 to 80°C or by air cooling, and then taken up at a spinning speed of 1 to 50 m / min and wound around a bobbin or the like.

[0099] The 3D printer filament preferably has a diameter of 0.5 to 3.5 mm, more preferably 1.0 to 3.2 mm. Specifically, since filaments for filament-type 3D printers with diameters of 1.75 mm and 2.85 mm are often used, the diameter is preferably 1.5 to 2.0 mm or 2.5 to 3 mm. If the diameter of the 3D printer filament falls outside the above range, it may not be suitable for a general-purpose 3D printer using a fused deposition modeling method. The diameter of the 3D printer filament is measured as the major axis in a cross section cut perpendicular to the longitudinal direction of the filament.

[0100] The circularity ratio, expressed as the ratio of the major axis to the minor axis (major axis / minor axis) in the cross section of the 3D printer filament, is preferably 1.05 or less, more preferably 1.03 or less. By having a circularity ratio of 1.05 or less, a shaped product can be more precisely formed in a filament-type 3D printer. Note that the closer the ratio of the major axis to the minor axis is to 1, the higher the circularity.

[0101] The 3D printer filament according to this embodiment can be applied to various filament-type 3D printers. FDM-type 3D printers that use filaments are generally classified into direct type and Bowden type.

[0102] In the direct method, the extruder is directly attached to the print head, and the filament is directly fed to the print head. Therefore, the distance from the end of the extruder gear feed to the nozzle inlet of the print head is short, for example, about 25 mm.

[0103] In contrast, the Bowden method is a method in which the extruder is attached away from the print head, and the filament is fed to the print head through a resin tube such as a PTFE tube. In the Bowden method, the distance from the end of the extruder's gear feed to the nozzle entrance of the print head is long, usually 50 mm or more, and there are also devices with a distance of 100 mm or 400 mm.

[0104] As mentioned above, in the direct method, the distance from the end of the gear feed to the nozzle entrance is short. Therefore, if the filament can be wound onto a bobbin, the filament fed out from the gear section can be heated by the heater in the print head, made fluid, and discharged from the nozzle to form a three-dimensional structure.

[0105] In contrast, in the Bowden method, the distance from the end of the gear feed to the nozzle inlet is long. Therefore, depending on the composition of the filament composition, the filament sent out from the gear section may break between the gear and the nozzle, making it impossible to extrude from the nozzle. This filament breakage occurs when the filament is deformed by the gear pressing in the gear section, causing cracks in the filament. Therefore, in order to enable normal extrusion from the nozzle even when the gear section and the nozzle are separated as in the Bowden method, it is necessary to suppress the occurrence of cracks due to the pressing of the gear and reliably transmit the extrusion pressure from the extruder to the nozzle, and to have fluidity to facilitate extrusion from the nozzle after heating and melting. To achieve this, it is necessary to increase hardness while maintaining flexibility (flexibility), and to have fluidity in the molten state.

[0106] In the filament composition according to the present embodiment, the above-mentioned thermoplastic resin (B1), thermoplastic resin (B2), olefin-based elastomer (B3) and compound (B5) are used as the organic binder (B), and the mass ratios (((B1)+(B5)) / (B)), ((B2) / (B)), ((B3) / (B)) and ((B5) / (B)) are set as described above, so that the composition has an excellent balance of hardness, flexibility and fluidity. Therefore, even when used in the Bowden method, the occurrence of cracks due to the pressing of the gear is suppressed, and the filament is less likely to break between the gear and the nozzle, so that the extrusion pressure of the extruder can be reliably transmitted to the nozzle. In addition, the composition melted by the heater part of the print head can be stably discharged from the nozzle.

[0107] The 3D printer filament according to this embodiment can be used as a material to manufacture a sintered body of the sinterable inorganic powder (A). Specifically, the method for manufacturing a sintered body of the sinterable inorganic powder (A) includes a step of forming a laminated structure by a filament-type 3D printer of the fused deposition modeling method using the 3D printer filament (laminate structure forming step), a step of degreasing the formed laminated structure (degreasing step), and a step of sintering the sinterable inorganic powder (A) in the degreasing laminated structure (sintering step).

[0108] The process of modeling the laminated structure can be performed, for example, by using the above-mentioned 3D printer filament with a commercially available filament-type 3D printer such as a direct type or a Bowden type. The 3D printer heats and melts the 3D printer filament with a heater unit, and the heating temperature at this time is preferably 100 to 300°C, more preferably 150 to 280°C, and even more preferably 170 to 250°C.

[0109] The debinding process is a process in which the laminated structure is heated to thermally decompose and remove the organic binder (B) in the laminated structure. In the debinding process, the laminated structure is heated at a temperature lower than that of the sintering process described later, that is, at a temperature at which the sinterable inorganic powder (A) does not sinter. In the debinding process, the organic binder (B) is decomposed and released as gas. This gas is released to the outside through the gaps between the sinterable inorganic powder (A) in the laminated structure and the organic binder (B) before decomposition. If there is no release path in the laminated structure, the laminated structure will be deformed by this gas. For example, the laminated structure may swell or crack due to the gas that has no escape route. If a filament made of the composition for filaments according to this embodiment is used, such deformation (hereinafter also referred to as "cracks and blisters") can be suppressed.

[0110] The sintering step is a step in which the sinterable inorganic powder (A) remaining after the debinding step is heated at a high temperature to sinter the sinterable inorganic powder (A) to obtain a sintered body.

[0111] The conditions for debinding and sintering can be appropriately set according to the type of inorganic powder contained in the composition. For example, when the inorganic powder is zirconia (yttria-stabilized zirconia, etc.) or alumina, the debinding can be performed by increasing the temperature to about 450-550°C at a rate of 5-20°C / h, and then increasing the temperature to 1300-1600°C at a rate of 40-60°C / h to perform sintering. When the inorganic powder is metal, the debinding can be performed by increasing the temperature to about 450-550°C at a rate of 5-20°C / h in an inert gas atmosphere, and then increasing the temperature to 1300-1400°C at a rate of 40-60°C / h to perform sintering. EXAMPLES

[0112] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0113] <Raw materials used> The raw materials used in the examples and comparative examples are as follows. [Sinterable inorganic powder (A)] Stainless steel powder (SUS316L powder, average particle size (D50): 7.1 μm, tap density: 4.6 g / cm 3 ) Zirconia powder (yttria-stabilized zirconia powder containing 3 mol% Y2O3, BET specific surface area: 15 m 2 / g, average particle diameter (D50): 0.15μm) Alumina powder (BET specific surface area: 6m 2 / g, average particle diameter (D50): 0.52μm) Silica powder (BET specific surface area: 5m 2 / g, average particle diameter (D50): 0.48μm) Aluminum nitride powder (BET specific surface area: 3.17 m 2 / g, average particle diameter (D50): 1.3μm) Silicon carbide powder (BET specific surface area: 14.8m 2 / g, average particle diameter (D50): 11μm) ·WC-Co powder (average particle diameter (D50): 1.4μm)

[0114] [Thermoplastic resin (B1)] Acrylic resin 1 (n-butyl methacrylate polymer, weight average molecular weight: 200,000) Acrylic resin 2 (copolymer of methyl methacrylate and n-butyl acrylate, "Clarity LA2140" manufactured by Kuraray Co., Ltd.) Acrylic resin 3 (copolymer of ethylene and glycidyl methacrylate, "Bondfast BF-30C" manufactured by Sumitomo Chemical Co., Ltd.) EVA (weight average molecular weight: 70,000, vinyl acetate content: 30% by mass, flow value at 140°C: 0.30 cm 3 / sec, deflection temperature under load: 68℃)

[0115] [Thermoplastic resin (B2)] POM (weight average molecular weight: 50,000, flow value at 180°C: 0.003 cm 3 / sec, melting point: 165℃) PP (weight average molecular weight: 240,000, flow value at 180°C: 0.051 cm 3 / sec, melting point: 163℃) PE (weight average molecular weight: 100,000, flow value at 180°C: 0.068 cm 3 / sec, melting point: 114℃)

[0116] [Olefin elastomer (B3)] Hydrogenated styrene / olefin copolymer 1 (hydrogenated block copolymer of styrene and butadiene, hardness: A67, flow start temperature: 134°C, styrene content: 18% by mass, 180°C flow value: 0.0023 cm 3 / sec) Hydrogenated styrene / olefin copolymer 2 (hydrogenated block copolymer of styrene and butadiene, hardness: A84, flow start temperature: 156°C, styrene content: 30% by mass, 190°C flow value: 0.0015 cm 3 / sec) Olefin copolymer (maleic anhydride modified ethylene-1-butene copolymer, hardness: A70, flow start temperature: 162°C, degree of modification: 2% by mass, flow value at 200°C: 0.0023 cm 3 / sec) Hydrogenated styrene / olefin copolymer 3 (comparison example, hydrogenated block copolymer of styrene and butadiene, hardness: A39, flow start temperature: 122°C, styrene content: 20% by mass, 150°C flow value: 0.002 cm 3 / sec) Amorphous polyolefin (comparison example, A hardness: 35, flow start temperature: 86°C)

[0117] [Paraffin wax (B4)] Paraffin wax (molecular weight: 472, melting point: 70°C)

[0118] [Compound (B5)] ·4-Cyclohexene-1,2-dicarboxylate bis(2-ethylhexyl) (weight average molecular weight (molecular weight): 394) Sorbitan monostearate (weight average molecular weight (molecular weight): 430, melting point: 55°C) Stearic acid (weight average molecular weight (molecular weight): 284)

[0119] Tables 1 to 5 show the "mixture" (raw materials and blending amounts) of each filament composition in Examples 1 to 38 and Comparative Examples 1 to 12, the "mass ratio" of the raw materials blended, the "characteristics" of each filament composition, and the "evaluation" of the 3D printer filament manufactured using each filament composition. Details of Tables 1 to 5 are explained below.

[0120] <Formulation> [Preparation of filament composition] The sinterable inorganic powder (A), thermoplastic resin (B1), thermoplastic resin (B2), olefin-based elastomer (B3), paraffin wax (B4) and compound (B5) were mixed in the ratios shown in Tables 1 to 5, and melt-kneaded at 170°C using a pressure kneader manufactured by Nihon Spindle Mfg. Co., Ltd. (formerly Moriyama Mfg. Co., Ltd.) to prepare compositions for filaments according to Examples 1 to 38 and Comparative Examples 1 to 12. The amounts shown in the tables are based on mass (parts by mass).

[0121] <Mass ratio> Tables 1 to 5 show the "mass ratios" of the raw materials contained in each filament composition. In the tables, (A), (B1), (B2), (B3), (B4), (B5), and (B) respectively indicate the masses of the sinterable inorganic powder (A), thermoplastic resin (B1), thermoplastic resin (B2), olefin-based elastomer (B3), paraffin wax (B4), compound (B5), and organic binder (B) in the filament composition.

[0122] <Characteristics> [200℃ flow value] The flow value of each filament composition at 200°C (200°C flow value) was measured in accordance with JIS (1999 edition) K7210 Appendix C. In detail, the flow value was measured at a measurement temperature of 200°C under the conditions that the die hole diameter was 1.0 mm, the die hole length was 1.0 mm, and the load on the sample (filament composition) was 0.98 MPa. The flow value was measured using a flow tester "CFD-500D" manufactured by Shimadzu Corporation. The unit of the flow value in the table is "cm 3 / sec". For samples whose fluidity was too low to be measured, the value "does not flow" is entered in the table.

[0123] [Flow start temperature] The flow start temperature of each filament composition was measured. In detail, the flow start temperature was determined as follows using a flow tester "CFD-500D" manufactured by Shimadzu Corporation. That is, under the conditions that the diameter of the die hole was 1.0 mm, the length of the die hole was 1.0 mm, and the load on the sample (filament composition) was 0.98 MPa (the same conditions as when the above flow value was measured), the temperature of the sample was raised from 25 ° C. at 5 ° C. / min, and the sample temperature when the dissolved sample flows out of the die was determined as the flow start temperature. The unit of the flow start temperature in the table is "° C." In addition, the flow start temperature that could not be measured because the flow was too low is described in the table as "does not flow."

[0124] <Evaluation> [Filament manufacturing] For each filament composition, a single-screw extruder manufactured by Enpla Sangyo Co., Ltd. was used to produce 3D printer filaments according to Examples 1 to 38 and Comparative Examples 1 to 12. In detail, the molten filament composition was extruded at a constant speed from a die heated to 165°C, and air-cooled at room temperature to produce the 3D printer filaments. The diameter of each of the obtained 3D printer filaments was 1.75 mm. In addition, the circularity of the cross section of the 3D printer filament (ratio of major axis to minor axis (major axis / minor axis)) was 1.02.

[0125] [Gear pressing evaluation] Filaments extruded from the gear of a 3D printer sink where they come into contact with the gear teeth. The presence or absence of cracks around the sinking area is observed, and this serves as an indicator of whether the filament will buckle after being extruded from the nozzle. The presence or absence of cracks in 3D printer filaments after extrusion through the gear was judged as follows: Each 3D printer filament was extruded with a 3D printer extrusion gear (diameter 12 mm, gear tooth length 0.5 mm, angle 90 degrees) at a pressing force of 50 N, and the surface of the extruded filament was observed with an optical microscope. Based on the results of the observation, the absence of cracks was judged according to the following criteria. ○: No cracks occurred ×: Cracks occurred and / or filaments were broken

[0126] [Break resistance] The resistance to breaking of each 3D printer filament was evaluated. "Resistance to breaking" is an index of whether or not a 3D printer filament can be easily wound onto a bobbin, etc. The resistance to breaking of 3D printer filaments was judged as follows: Each 3D printer filament was prepared by cutting it to a length of 20 cm, and then wrapped once around a rod with a diameter of 6 cm. The number of repetitions was counted until the 3D printer filament broke after unwinding and straightening it, and the judging criteria were as follows: A, B, and C were considered pass, and D was considered fail. A: No breakage even after 21 repetitions B: Breaking occurs at repetitions 11 to 20. C: Breaking occurs after 5 to 10 repetitions D: Breaking occurs after less than 5 repetitions

[0127] [Manufacturing stability] (less likely to cause defects around the gears) The resistance to defects around the gear part when a laminated structure was produced using each 3D printer filament was evaluated. Here, the resistance to defects around the gear part is referred to as manufacturing stability. In detail, a cylinder (laminated structure) with an outer diameter of 80 mm, an inner diameter of 75 mm, and a height of 100 mm was produced using a filament-type 3D printer (Bowden method, FLASHFORGE's "ADVENTURER 3X", modeling range: X150mm x Y150mm x Z150mm, distance from gear to nozzle: 400mm) using each manufactured 3D printer filament as material. The modeling speed at that time was 30 mm / sec, the modeling nozzle temperature was 240 ° C, the stage temperature was 100 ° C, and the nozzle diameter was 0.4 mm.

[0128] The laminated structures used in the evaluations of [nozzle discharge stability and lamination property], [freeness of deformation] and [relative density] were also prepared in the same manner as in [production stability].

[0129] When a 3D printer is operating normally, the gear section that feeds the filament feeds the filament normally, but if the filament buckles or breaks in the gear section, or if the filament is scraped off by the gear, the filament cannot be fed normally, and as a result, normal modeling cannot be performed. Here, the time from the start of modeling to when such a malfunction occurs was measured to determine the likelihood of malfunctions occurring around the gear section when using each 3D printer filament, i.e., manufacturing stability. The evaluation criteria are as follows: A, B, and C were considered pass, and D was considered fail. A: No problems even after 120 minutes or more from the start of printing. B: A defect occurs between 60 and 120 minutes after the start of printing. C: A defect occurs between 30 and 60 minutes after the start of printing. D: A defect occurs within 30 minutes of starting printing.

[0130] [Nozzle discharge stability and lamination] The nozzle discharge stability and lamination properties were evaluated when a laminated structure was produced using each 3D printer filament. In a filament-type 3D printer, the filament is melted in a heater and discharged from a nozzle. For example, if the flow value of a 3D printer filament is too low or too high, the amount of composition discharged from the nozzle tends to be uneven, and the surface of the laminated structure may become uneven, resulting in a defective appearance. Here, the difficulty of such unevenness (lack of fluctuation in the discharge amount) is referred to as nozzle discharge stability.

[0131] In addition, in a composition for 3D printer filaments, for example, if the mass ratio (((B1)+(B5)) / (B)) of the total of the thermoplastic resin (B1) and the compound (B5) to the organic binder (B) is too low, the adhesion between the layers in the laminated structure tends to decrease. Poor adhesion can cause defects such as gaps between the layers. Here, the resistance to such defects is referred to as lamination property.

[0132] The nozzle discharge stability and lamination properties were judged based on the appearance of the laminated structure, etc. The judgment criteria were as follows: A, B, and C were considered to be pass, and D was considered to be fail. A: There are no defects due to poor adhesion, and no unevenness in the discharge volume is observed. B: No defects due to poor adhesion, but slight unevenness in the discharge volume C: No defects due to poor adhesion, but moderate unevenness in discharge volume D: Defects due to poor adhesion or severe unevenness in the discharge volume

[0133] Here, the presence or absence of "defects due to poor adhesion" was judged by whether or not gaps were observed between layers in the obtained laminated structure. In addition, when the composition is discharged from the nozzle, it is pressed against the lower layer at the tip of the nozzle and laminated in a spread state. Therefore, if the amount of discharge from the nozzle is not stable, the width of the composition after being discharged varies greatly. As a result, unevenness occurs on the side of the obtained laminated structure. The above-mentioned "mild unevenness", "moderate unevenness", and "severe unevenness" were judged as follows when unevenness caused by such unevenness in the amount of discharge was observed in the laminated structure. That is, when the difference in the height direction of the largest unevenness among the unevennesses observed on the side of the laminated structure is less than 0.4 mm, it was judged as "mild unevenness", when the difference is 0.4 to 0.8 mm, it was judged as "moderate unevenness", and when the difference is more than 0.8 mm, it was judged as "severe unevenness".

[0134] [Lack of deformation] The laminated structures produced using each 3D printer filament were evaluated for deformation such as cracks and blisters that occurred after the degreasing process. In detail, for the laminated structures containing stainless steel powder as the sinterable inorganic powder (A) (Examples 1 to 22 and Comparative Examples 3 to 6 and 9 to 12), the degreasing was performed by heating up to 500°C at a heating rate of 10°C / h in a nitrogen gas atmosphere, and then cooling down to 30°C, and the state of the laminated structures after degreasing was observed.

[0135] For the laminated structures containing zirconia powder, alumina powder, silica powder, aluminum nitride powder, or silicon carbide powder as the sinterable inorganic powder (A) (Examples 23 to 33, 36 to 38 and Comparative Examples 1, 7 to 8), the temperature was increased to 500°C at a rate of 10°C / h in the atmosphere, degreased, and then cooled to 30°C, and the state of the laminated structures after degreasing was observed.

[0136] The laminated structures containing WC-Co powder as the sinterable inorganic powder (A) (Examples 34 to 35 and Comparative Example 2) were degreased by heating to 500°C at a heating rate of 10°C / h in a nitrogen gas atmosphere, cooled to 30°C, and the state of the laminated structures after degreasing was observed.

[0137] Based on the observation results, the absence of deformation was judged according to the following criteria: When a laminate structure could not be molded under the above-mentioned conditions, it was noted in the table as "unable to mold." 〇: No deformation △: No cracks or bulges, but some other minor deformations ×: Cracks or blisters are present, or other severe deformations are present

[0138] Here, the above-mentioned "mild deformation" and "severe deformation" were judged as follows. That is, for the laminated structure after degreasing, the maximum and minimum diameter and height of the cylinder were measured, and the degree of deviation from the designed position (the position where it should be) was measured. Then, if the maximum deviation of each apex was less than 5 mm, it was judged as "mild deformation", and if it was 5 mm or more, it was judged as "severe deformation".

[0139] Relative Density The relative density of the sintered bodies obtained through the sintering process for the laminated structures produced using each 3D printer filament was measured. Each sintered body was obtained as follows.

[0140] For the laminated structures (Examples 1 to 22 and Comparative Examples 3 to 6, 9 to 12) containing stainless steel powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then the structures were sintered in a nitrogen gas atmosphere by increasing the temperature to 1,350°C at a heating rate of 50°C / h to obtain sintered bodies.

[0141] For the laminated structures (Examples 23 to 26) containing zirconia powder as the sinterable inorganic powder (A), the absence of deformation was observed as described above, and then the temperature was increased to 1450°C at a rate of 50°C / h in air, and sintering was performed to obtain sintered bodies.

[0142] For the laminated structures (Examples 27 to 33 and Comparative Examples 7 to 8) containing alumina powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then sintering was performed by heating up to 1600°C at a heating rate of 50°C / h in air to obtain sintered bodies.

[0143] For the laminated structures (Example 36 and Comparative Example 1) containing silica powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then sintering was performed by heating up to 1250°C at a heating rate of 50°C / h in air to obtain a sintered body.

[0144] As for the laminated structure (Example 37) containing aluminum nitride powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then the temperature was raised to 1800°C at a heating rate of 50°C / h in the air to sinter, thereby obtaining a sintered body.

[0145] As for the laminated structure (Example 38) containing silicon nitride powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then the temperature was increased to 2100°C at a heating rate of 50°C / h in air to sinter, thereby obtaining a sintered body.

[0146] As for the laminated structures (Examples 34 to 35 and Comparative Example 2) containing WC-Co powder as the sinterable inorganic powder (A), the state was observed for the absence of deformation as described above, and then the structures were sintered by heating to a temperature of 1390°C at a heating rate of 50°C / h in an argon gas atmosphere to obtain sintered bodies.

[0147] The apparent density of each sintered body was measured by Archimedes' method, and the ratio of the apparent density to the true density was taken as the relative density. The relative density is preferably 95% or more. If the relative density is less than 95%, the sintered body may have bubbles or the like inside. The relative density was judged according to the following criteria. Here, "true density" refers to the true density of the components constituting each sintered body, i.e., the components of the sinterable inorganic powder (A) used, and for example, in Example 1, it is the true density of the stainless steel used. ○: Relative density is 95% or more ×: Relative density is less than 95%

[0148] [Table 1]

[0149] [Table 2]

[0150] [Table 3]

[0151] [Table 4]

[0152] [Table 5]

[0153] The following can be seen from each Example and Comparative Example. That is, when the organic binder (B) was less than 5 parts by mass per 100 parts by mass of the sinterable inorganic powder (A) (Comparative Example 2), cracks were generated by pressing the gear, the filament was easily broken, and the fluidity of the composition for the filament was poor, so that a laminated structure could not be manufactured. When the organic binder (B) exceeded 55 parts by mass (Comparative Example 1), the manufacturing stability was poor, deformation after degreasing was large, and a sintered body with a high relative density could not be obtained.

[0154] When the mass ratio (((B1)+(B5)) / (B)) of the sum of the thermoplastic resin (B1) and the compound (B5) to the total amount of the organic binder (B) was less than 0.10 (Comparative Example 4), the lamination was poor, and a sintered body with a high relative density could not be obtained. When the mass ratio exceeded 0.60 (Comparative Example 3), cracks occurred due to the pressing of the gear, the filaments were easily broken, and deformation after degreasing was large.

[0155] When the mass ratio ((B2) / (B)) of the thermoplastic resin (B2) to the total amount of the organic binder (B) was less than 0.05 (Comparative Example 6), cracks occurred due to the pressing of the gear, and deformation after degreasing was large, making it impossible to obtain a sintered body with a high relative density. When the mass ratio exceeded 0.80 (Comparative Example 5), the manufacturing stability and nozzle discharge stability were poor, making it impossible to form a laminated structure.

[0156] When the mass ratio ((B3) / (B)) of the olefin-based elastomer (B3) to the total amount of the organic binder (B) was less than 0.03 (Comparative Example 8), cracks occurred due to gear pressing, the filaments were easily broken, and the nozzle discharge stability was also poor. When the mass ratio exceeded 0.60 (Comparative Example 7), the gear pressing evaluation and manufacturing stability were poor, and the laminate structure could not be molded.

[0157] When the mass ratio of compound (B5) to the total amount of organic binder (B) ((B5) / (B)) was less than 0.02 (Comparative Example 10), cracks occurred due to the pressing of the gear, the filaments were easily broken, and a sintered body with a high relative density could not be obtained. When the mass ratio exceeded 0.20 (Comparative Example 9), cracks occurred due to the pressing of the gear, the manufacturing stability and the nozzle discharge stability were poor, and deformation after degreasing was large.

[0158] When hydrogenated styrene / olefin copolymer 3 with hardness and flow starting temperature below the specified level was used as olefin elastomer (B3) (Comparative Example 11), the gear pressing evaluation and manufacturing stability were poor, and a laminate structure could not be molded. Also, when an unspecified amorphous polyolefin was used as olefin elastomer (B3) (Comparative Example 12), the gear pressing evaluation and manufacturing stability were poor, and deformation after degreasing was large.

[0159] In contrast, the organic binder (B) is 5 to 55 parts by mass relative to 100 parts by mass of the sinterable inorganic powder (A), the mass ratio of the total of the thermoplastic resin (B1) and the compound (B5) to the organic binder (B) (((B1)+(B5)) / (B)) is 0.10 to 0.60, the mass ratio of the thermoplastic resin (B2) to the organic binder (B) ((B2) / (B)) is 0.05 to 0.80, and the mass ratio of the olefin (O) to the organic binder (B) is 0.05 to 0.50. In Examples 1 to 38 in which the mass ratio ((B3) / (B)) of the fin-based elastomer (B3) is 0.03 to 0.60 and the mass ratio ((B5) / (B)) of the compound (B5) to the organic binder (B) is in the range of 0.02 to 0.20, it is possible to normally discharge the molten composition from the nozzle of the filament-type 3D printer, and it is possible to obtain a 3D printer filament capable of forming a sintered body with excellent appearance. More specifically, when the filament composition of each Example is used, it is possible to obtain a 3D printer filament that does not crack due to the pressing of the gear, is not easily broken, has high manufacturing stability, has high nozzle discharge stability and lamination property, and also has small deformation during degreasing and a sintered body with high relative density.

[0160] In particular, by using an olefin-based elastomer (B3) having the specified hardness and flow starting temperature, as shown in Examples 7, 18 to 20, 29 to 31, and 37, even when the mass ratio ((B2) / (B)) of the thermoplastic resin (B2) to the organic binder (B) was reduced to 0.25 or less, the gear pressing evaluation and production stability were excellent, and it was possible to improve adhesion without impairing these properties.

[0161] Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their omissions, substitutions, modifications, etc. are included in the scope of the invention described in the claims and their equivalents, as well as in the scope and gist of the invention. In addition, the various numerical ranges described in the specification can be arbitrarily combined with their upper and lower limits, and all of these combinations are described in this specification as preferred numerical ranges. In addition, the description of a numerical range as "X to Y" means X or more and Y or less. In addition, in this specification, it may be described that a certain compound Z is a compound obtained by reacting compound X with compound Y, but in such a case, compound Z does not necessarily have to be a compound obtained by reacting compound X with compound Y. In other words, compound Z may have the same structure as a compound obtained by reacting compound X with compound Y, and the manufacturing process is not relevant. [Industrial Applicability]

[0162] According to the present invention, it is possible to efficiently manufacture ceramic products, metal products, cermets, and the like with excellent appearance using a filament-type 3D printer.

Claims

1. A filament composition for use in a filament-type 3D printer, comprising: Contains a sinterable inorganic powder (A) and an organic binder (B), The organic binder (B) is at least one olefin-based elastomer selected from the group consisting of copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, hydrogenated copolymers of unsaturated aliphatic hydrocarbons and aromatic vinyl compounds, and copolymers of two or more kinds of unsaturated aliphatic hydrocarbons, the olefin-based elastomer having a hardness of A60 or more and a flow-initiation temperature of 130° C. or more (B3); at least one thermoplastic resin (B1) selected from the group consisting of non-crystalline polymers other than the olefin-based elastomer (B3) and EVA; A compound (B5) having a weight average molecular weight of 8,000 or less, excluding the olefin-based elastomer (B3), the thermoplastic resin (B1), and the paraffin wax (B4), and a thermoplastic resin (B2) selected from crystalline polymers excluding the EVA, the olefin-based elastomer (B3), and the compound (B5); The amount of the organic binder (B) is 5 to 55 parts by mass based on 100 parts by mass of the sinterable inorganic powder (A), a mass ratio (((B1)+(B5)) / (B)) of the sum of the thermoplastic resin (B1) and the compound (B5) to the organic binder (B) is 0.10 to 0.60; a mass ratio ((B2) / (B)) of the thermoplastic resin (B2) to the organic binder (B) is 0.05 to 0.80; a mass ratio ((B3) / (B)) of the olefin-based elastomer (B3) to the organic binder (B) is 0.03 to 0.60; A composition for 3D printer filaments, wherein the mass ratio ((B5) / (B)) of the compound (B5) to the organic binder (B) is 0.02 to 0.

20.

2. The composition for a filament of a 3D printer according to claim 1, wherein the thermoplastic resin (B1) comprises at least one selected from the group consisting of a (meth)acrylic acid ester polymer and EVA.

3. The composition for a filament of a 3D printer according to claim 1, wherein the thermoplastic resin (B2) includes at least one selected from the group consisting of polyacetal, polyethylene, and polypropylene.

4. The compound (B5) includes at least one selected from the group consisting of fatty acids, fatty acid esters, fatty acid amides, fatty acid salts, diesters having a carbon ring, phosphate esters, and phenol compounds. The composition for a filament of a 3D printer according to claim 1.

5. The composition for a filament of a 3D printer according to claim 1, wherein the mass ratio ((B4) / (B)) of the paraffin wax (B4) to the organic binder (B) is 0.25 or less.

6. The olefin-based elastomer (B3) includes a hydrogenated product of a block copolymer of styrene and butadiene, and / or an acid-modified ethylene-α-olefin copolymer.

7. A 3D printer filament produced using the filament composition according to any one of claims 1 to 6.

8. A sintered body of the sinterable inorganic powder (A) produced using the 3D printer filament according to claim 7.

9. A method for producing a sintered body of a sinterable inorganic powder (A), comprising the steps of: A method for producing a sintered body, comprising the steps of: forming a laminated structure by a filament-type 3D printer using the 3D printer filament according to claim 7; degreasing the formed laminated structure; and sintering the sinterable inorganic powder (A) in the degreased laminated structure.

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