Additive manufactured article and method for producing additive manufactured article

Abstract

Provided are: an additive manufactured article in which warping and surface unevenness are suppressed even if a resin with a certain water absorption rate or higher is used; and a method for producing the additive manufactured article.　The additive manufactured article has a resin composition that includes a resin (A) with a saturated water absorption rate of at least 0.2% as measured in compliance with ASTM D570, and plate-shaped particles (B); the content of the plate-shaped particles (B) in the resin composition is 7–40% by mass; the mean grain diameter (D50) of the plate-shaped particles is at least 2 μm; and the surface arithmetic mean height of the layered molded article is less than 100 μm. The method for manufacturing an additive manufactured article includes additive manufacturing with a resin composition that includes a resin (A) with a saturated water absorption rate of at least 0.2% as measured in compliance with ASTM D570, and plate-shaped particles (B), where the content of the plate-shaped particle (B) is 7–40% by mass, while keeping the water absorption rate of the resin composition below 0.2%.

Description

Layered object and method for manufacturing layered object

[0001] The present disclosure relates to an additively shaped object and a method for manufacturing the additively shaped object.

[0002] 3D printers are a type of additive manufacturing machine that uses 3D data created on a computer, such as CAD or CG, as blueprints to produce three-dimensional objects made of plastic or other materials.

[0003] Generally, 3D printers are classified by the deposition method, and known methods include binder jetting, fused deposition modeling, liquid vat photopolymerization, and powder sintering (SLS (Selective Laser Sintering) or SLM (Selective Laser Melting)) methods.

[0004] 3D printers use resin materials to create additively manufactured objects. For example, in fused deposition modeling (FDM), filaments of thermoplastic resin are used as the material. These filaments are melted and extruded from the nozzle of the 3D printer, layering them to form the desired shape. Filaments used in FDM 3D printers typically include polylactic acid resin (PLA resin) and acrylonitrile-styrene-butadiene resin (ABS resin). While ABS resin is known for its heat resistance and excellent post-processability, it often warps during modeling. Therefore, a filament made of a thermoplastic resin, a thermoplastic elastomer, and talc has been proposed (Patent Document 1). However, unlike non-absorbent resins such as polypropylene resin, when using a water-absorbent resin like ABS, the resin absorbs water over a certain period of time after drying. Furthermore, it was found that the inclusion of talc caused surface irregularities to occur, making the material unsuitable for practical use.

[0005] International Publication No. 2021 / 060278

[0006] Therefore, an object of the present disclosure is to provide an additive manufacturing object in which warping and surface unevenness are suppressed even when a resin having a water absorption rate above a certain level is used, and a method for manufacturing the same.

[0007] As a result of extensive research, the present inventors discovered that the above-mentioned problems can be solved by blending a specific amount of plate-shaped particles and performing additive manufacturing while maintaining the water absorption of the resin composition at 0.2% or less, and thus completed the present invention. Specifically, the present disclosure includes the following aspects: [1] An additively manufactured product of a resin composition containing a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-shaped particles (B), wherein the content of the plate-shaped particles (B) in the resin composition is 7 to 40% by mass, the average particle diameter (D50) of the plate-shaped particles is 2 μm or more, and the arithmetic mean height of the surface of the additively manufactured product is less than 100 μm. [2] A method for producing an additively molded product, comprising additively manufacturing a resin composition containing a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-like particles (B), wherein the content of the plate-like particles (B) is 7 to 40% by mass, while maintaining the water absorption of the resin composition at less than 0.2%.

[0008] According to the present disclosure, it is possible to provide a method for manufacturing a layered object in which warping and surface irregularities are suppressed, even when a resin having a water absorption rate equal to or higher than a certain level is used.

[0009] 1A and 1B are diagrams illustrating the surface of a layered object according to an example of the present disclosure and a comparative example of the present disclosure;

[0010] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limit values ​​are described for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limit values ​​of a numerical range described in this disclosure are numerical values ​​within that numerical range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0011] [Method for Manufacturing Layer-by-Layer Manufactured Product] The method for manufacturing a layer-by-layer shaped product according to this embodiment includes layer-by-layer manufacturing a resin composition containing a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-like particles (B), the resin composition containing 7 to 40% by mass of the plate-like particles (B), while maintaining the water absorption of the resin composition at less than 0.2%. The resin composition used in this manufacturing method includes a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-like particles (B), the content of which is 7 to 40% by mass of the plate-like particles (B) relative to the total mass of the resin composition. This manufacturing method according to this embodiment enables the production of layer-by-layer shaped products with reduced warping and surface irregularities.

[0012] Here, "warping" refers to a phenomenon in which, when a layered object is manufactured using a 3D printer, at least a portion of the resin composition layered on a substrate peels off from the substrate surface, creating a gap (floating) between the substrate and the layered object. Here, "occurrence of warping" refers, for example, to a layered object warping of 1 mm or more. When this phenomenon occurs, problems occur, such as difficulty in obtaining a layered object with the desired shape, or the layered object coming into contact with the nozzle of the 3D printer, preventing further manufacturing. The manufacturing method according to this embodiment suppresses warping during manufacturing, allowing layered objects with the desired shape to be obtained. It can also prevent problems during manufacturing caused by warping. In this specification, "laminate" refers to a layered object in the middle of being manufactured. The warping of a layered object can be measured by placing a layered object (e.g., an evaluation sample plate measuring 200 mm wide x 50 mm long x 4 mm thick) on a horizontal plate, measuring the gap distance between the bottom surface of the layered object and the horizontal plate with a curved ruler, and determining the maximum value (floating amount).

[0013] By using the manufacturing method of this embodiment, not only can warping be suppressed, but the occurrence of surface irregularities can also be suppressed. Here, "occurrence of surface irregularities" refers, for example, to the surface arithmetic mean height of the layered object being 100 μm or more or 40 μm or more. If surface irregularities occur, the impact strength of the resulting layered object will deteriorate and it will no longer be suitable for practical use. By using the manufacturing method of this embodiment, the occurrence of surface irregularities is suppressed, and layered object with excellent impact strength can be manufactured. The surface arithmetic mean height of the layered object can be measured by measuring the surface of the layered object using a 3D measuring laser microscope (for example, "LEXT OLS5100" manufactured by Evident Co., Ltd.) in accordance with ISO 25178.

[0014] In the manufacturing method of this embodiment, additive manufacturing is performed while maintaining the water absorption of the resin composition at less than 0.2%, but the water absorption of the resin composition is more preferably maintained at less than 0.15%, and even more preferably maintained at less than 0.1%. The water absorption of the resin composition can be measured or calculated as follows: A certain amount (100 g) of filament formed from the resin composition is wound around a metal bobbin whose weight has been measured, and dried at 80°C for 2 hours. Thereafter, the weight change is measured over time in an environmental test chamber where the temperature and humidity are controlled (for example, a temperature of 20°C and a relative humidity of 30%, or a temperature of 20°C and a relative humidity of 50%), and the water absorption of the resin composition is calculated from the increased weight.

[0015] Furthermore, when layer-by-layer manufacturing of the resin composition is performed, layer-by-layer manufacturing is preferably performed in an atmosphere of 10° C. or higher, more preferably in an atmosphere of 20° C. or higher, and even more preferably in an atmosphere of 25° C. or higher.

[0016] In one embodiment, additive manufacturing while maintaining the water absorption rate of the resin composition at less than 0.2% includes additive manufacturing in an atmosphere with a relative humidity of 40% or less. Additive manufacturing in an atmosphere with a relative humidity of 30% or less is more preferable, and additive manufacturing in an atmosphere with a relative humidity of 20% or less is even more preferable. Additive manufacturing in an atmosphere with a relative humidity of 40% or less makes it easier to prevent the resin composition from absorbing moisture from the air during additive manufacturing, resulting in the resin composition's water absorption rate reaching 0.2% or more. A specific method for additive manufacturing in an atmosphere with a relative humidity of 40% or less is, for example, to perform additive manufacturing in a dry box that isolates the resin composition and laminate from external airflow, and adjusts the relative humidity of the air in the dry box to 40% or less. Additive manufacturing may be performed by placing the entire 3D printer in the dry box, or by using a dry box (moisture-proof box) connectable to the 3D printer and used to contain only the resin composition. The relative humidity of the air in the dry box is preferably 30% or less, and more preferably 20% or less. The temperature inside the drying box is not particularly limited as long as it is a temperature suitable for additive manufacturing, but is preferably 10° C. or higher, more preferably 20° C. or higher, and even more preferably 25° C. or higher. Another option is to adjust the relative humidity and temperature of the entire room where additive manufacturing is performed.

[0017] In one embodiment, the method for manufacturing an additive manufacturing object includes drying the resin composition so that the water absorption of the resin composition is less than 0.2%. Drying the resin composition is preferably performed before additive manufacturing using the resin composition. Drying the resin composition includes heating the resin composition to a certain temperature or higher or placing the resin composition in an atmosphere with a certain relative humidity or lower in order to reduce the water absorption of the resin composition. The temperature when heating and drying the resin composition is preferably 70°C or higher but lower than 100°C, more preferably 70 to 95°C, and even more preferably 70 to 90°C. The time for heat-drying the resin composition is not particularly limited as long as the water absorption of the resin composition is less than 0.2%, but is preferably 1 to 10 hours, more preferably 1 to 8 hours, and even more preferably 1.5 to 5 hours. When the resin composition is dried in an atmosphere with a certain relative humidity or lower, it is preferably placed in an atmosphere with a relative humidity of 30% or lower, more preferably 20% or lower, and even more preferably 10% or lower. In this case, the drying time is not particularly limited as long as the water absorption of the resin composition is less than 0.2%, but is preferably 1 to 24 hours, more preferably 1 to 12 hours, and even more preferably 1.5 to 8 hours. In one embodiment, the method for producing an additive manufacturing product includes drying the resin composition by any of the above means so that the water absorption of the resin composition is less than 0.2%, and additive manufacturing in an atmosphere with a relative humidity of 40% or less.

[0018] In one embodiment, the method for producing an additively shaped object includes melting the resin composition and extruding the molten resin composition from a nozzle to form an additively shaped object. The production method according to this embodiment is preferably a method for producing an additively shaped object using an FDM 3D printer. When the resin composition according to this embodiment is used as a raw material resin for an FDM 3D printer, the resin composition is formed into a filament shape.

[0019] FDM 3D printers generally include a heatable substrate (modeling table), an extrusion head (nozzle), a heat melter, a filament guide, a filament installation, and other raw material supply units. Some FDM 3D printers have an integrated nozzle and heat melter.

[0020] The nozzle is installed in a gantry structure, allowing it to move freely on the X-Y plane of the substrate. The substrate is a platform for constructing the desired three-dimensional object, support material, etc. The substrate configuration is not particularly limited, but a configuration that can be heated and kept warm is preferable from the perspective of easily improving the adhesion and dimensional stability of the laminate. Typically, at least one of the nozzle and the substrate is movable in the Z-axis direction, which is perpendicular to the X-Y plane.

[0021] In a preferred embodiment, a filament made of the resin composition of this embodiment is unwound from a raw material supply unit and fed into a nozzle by a pair of opposing rollers or gears. The filament is then heated and melted in the nozzle, and the molten filament is extruded from the tip of the nozzle. The nozzle moves in response to a signal transmitted based on the CAD model, supplying and stacking the molten filament onto the substrate to form an additive manufacturing object. After this process is complete, the laminated object can be removed from the substrate, and the desired additive manufacturing object can be obtained by peeling off support materials or trimming off excess portions as needed.

[0022] The filament may be supplied to the nozzle by unwinding it, for example. It is preferable that the filament be stored in a cartridge wound into a bobbin, from the viewpoints of stable unwinding, protection from environmental factors such as humidity, and prevention of twisting and kinking.

[0023] A preferred method for feeding the filament to the nozzle while unwinding it is to engage the filament with a driving roll such as a nip roll or a gear roll, and feed the filament to the nozzle while drawing it up. From the viewpoint of stabilizing the filament feeding by more firmly gripping the filament by the engagement between the filament and the driving roll, a fine concave-convex pattern may be transferred onto the surface of the filament.

[0024] In the manufacturing method according to the present embodiment, the nozzle temperature is preferably set to 220 to 260° C., more preferably 240 to 260° C., to melt the filaments made of the resin composition. The substrate temperature is preferably set to 110° C. or less, more preferably 100° C. or less.

[0025] In addition, since the resin composition according to this embodiment has excellent high-speed modeling properties, the modeling speed can be set high. In one embodiment, the modeling speed may be 80 to 150 mm / s, or 90 to 120 mm / s.

[0026] In one embodiment, from the viewpoint of obtaining a layered object with less warping, the manufacturing atmosphere temperature inside the 3D printer is preferably room temperature to 50°C, more preferably 30 to 40°C.

[0027] <Resin (A) with a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570> The resin composition of this embodiment contains a resin (A) (hereinafter referred to as "resin (A)") with a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570. A "resin with a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570" refers to a resin that exhibits a certain level of water absorption or more, and has a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570. By combining resin (A) with plate-like particles (B) described below and performing additive manufacturing while maintaining the water absorption of the resin composition at less than 0.2%, an additive manufacturing product with reduced warping and surface unevenness can be produced. The saturated water absorption of the resin (A), measured in accordance with ASTM D570, is preferably 0.2% or more and 0.6% or less, more preferably 0.2% or more and 0.5% or less, and even more preferably 0.2% or more and 0.4% or less.

[0028] Examples of resins having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 include styrene-based resins, polyvinyl alcohol resins, acrylic-based resins, nylon-based resins, polyacetal-based resins, polyimide-based resins, and polybenzimidazole-based resins.

[0029] "Styrene-based resin" refers to a polymer containing, as a main component, a compound having a styrene skeleton. "Containing, as a main component, a compound having a styrene skeleton" means that the proportion of the compound having a styrene skeleton relative to the total amount (100% by mass) of raw material monomers is greater than 50% by mass. This proportion may be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or even 95% by mass or more. Examples of compounds having a styrene skeleton include styrene, α-methylstyrene, paramethylstyrene, vinyltoluene, and vinylxylene, with styrene being preferred.

[0030] In one embodiment, the styrene-based resin may be a copolymer obtained by copolymerizing the above-described compound having a styrene skeleton with another monomer. Examples of such copolymers include acrylonitrile-styrene copolymer (AS resin) and maleic anhydride-styrene copolymer (maleic anhydride-modified polystyrene resin).

[0031] In one embodiment, the resin (A) preferably contains a rubber component-containing styrene-based resin. Examples of the rubber component include conjugated diene rubber and non-diene rubber. Examples of conjugated diene rubber include conjugated diene hydrocarbons such as butadiene, isoprene, and 1,3-pentadiene. Examples of non-diene rubber include silicone rubber, ethylene-propylene rubber, acrylic rubber, and urethane rubber. Examples of styrene-based resins containing such conjugated diene rubber or non-diene rubber include acrylonitrile-styrene-butadiene copolymer (ABS resin); AXS resins such as acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS resin), and acrylonitrile-(ethylene-propylene-diene rubber)-styrene copolymer (AES resin). These styrene-based resins containing rubber components can be used as the resin (A) either singly or in combination.

[0032] In one embodiment, the resin (A) preferably contains a conjugated diene rubber as a rubber component. When the resin (A) contains a styrene-based resin containing a conjugated diene rubber, the molding processability is improved. In a more preferred embodiment, the resin (A) contains an ABS resin.

[0033] (ABS Resin) When resin (A) contains an ABS resin, the ABS resin preferably contains butadiene in an amount of 12 to 22% by mass, more preferably 16 to 20% by mass, relative to the total mass of the ABS resin. Furthermore, as described above, resin (A) may be a mixture of two or more types of ABS resins.

[0034] In one embodiment, the ABS resin preferably has an MFR (220°C, 10 kg load) of 10 to 30 g / 10 min, more preferably 15 to 30 g / 10 min, and even more preferably 20 to 30 g / 10 min. Using an ABS resin with such an MFR (220°C, 10 kg load) improves high-speed molding properties. When two or more types of ABS resins are used as resin (A), the blending ratio of each ABS resin may be adjusted so that the MFR (220°C, 10 kg load) of the ABS resin blend is 10 to 30 g / 10 min. For example, ABS resin 1 having an MFR (220°C, 10 kg load) of 30 to 45 g / 10 min and ABS resin 2 having an MFR (220°C, 10 kg load) of 10 to 15 g / 10 min may be combined in a ratio of ABS resin 1:ABS resin 2 in the range of 3 to 7:7 to 3.

[0035] When resin (A) contains an ABS resin, the proportion of the ABS resin in resin (A) is preferably 50% by mass or more, more preferably 80% by mass or more, relative to the total mass of resin (A). Resin (A) may also contain only ABS resin. That is, the proportion of resin (A) in resin (A) may be 50 to 100% by mass, or 80 to 100% by mass.

[0036] The "polyvinyl alcohol resin" can be used as a surfactant (e.g., a nonionic emulsifier). The polyvinyl alcohol resin can be obtained by saponifying a homopolymer of a vinyl ester or a copolymer of a vinyl ester and a monomer copolymerizable with the vinyl ester.

[0037] Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. The vinyl ester may contain vinyl acetate from the viewpoint of excellent stability during polymerization.

[0038] Examples of monomers copolymerizable with vinyl esters include olefins such as ethylene, propylene, 1-butene, and isobutene; unsaturated acids such as (meth)acrylic acid, crotonic acid, phthalic acid, maleic acid, and itaconic acid; salts of the unsaturated acids; (meth)acrylamide compounds such as (meth)acrylamide, N-alkyl(meth)acrylamides having 1 to 18 carbon atoms, N,N-dialkyl(meth)acrylamides, diacetone(meth)acrylamide, 2-(meth)acrylamidopropanesulfonic acid and salts thereof, and (meth)acrylamidopropyldimethylamine and salts thereof; 3,4-diacetoxy-1-butene; glycerin monoallyl ether; alkyl acrylates having 1 to 18 carbon atoms; vinyl ether compounds such as alkyl vinyl ethers, hydroxyalkyl vinyl ethers, and alkoxyalkyl vinyl ethers having an alkyl chain; N-vinyl amides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as (meth)acrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide, and vinylidene bromide; vinyl silanes such as trimethoxyvinylsilane; allyl compounds such as allyl acetate, allyl chloride, allyl alcohol, and dimethylallyl alcohol; vinyl silyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.

[0039] The saponification degree of the polyvinyl alcohol resin may be in the following ranges from the viewpoint of easily obtaining sufficient adhesive strength to the wet surface of concrete and from the viewpoint of easily obtaining sufficient mechanical strength (e.g., tensile break strength). The saponification degree may be 50.0 mol% or more, 60.0 mol% or more, 70.0 mol% or more, 75.0 mol% or more, 80.0 mol% or more, or 85.0 mol% or more. The saponification degree may be 99.0 mol% or less, 97.0 mol% or less, 96.5 mol% or less, 95.0 mol% or less, 90.0 mol% or less, 85.0 mol% or less, or 80.0 mol% or less. From these viewpoints, the saponification degree may be 50.0 to 99.0 mol%, 70.0 to 96.5 mol%, or 75.0 to 90.0 mol%.

[0040] The degree of polymerization of the polyvinyl alcohol resin may be in the following ranges from the viewpoint of easily obtaining sufficient adhesive strength to the wet surface of concrete and from the viewpoint of easily obtaining sufficient mechanical strength (e.g., tensile break strength). The degree of polymerization may be 100 or more, 150 or more, 200 or more, 250 or more, 300 or more, 350 or more, 400 or more, 450 or more, or 500 or more. The degree of polymerization may be 5000 or less, 4500 or less, 4000 or less, 3000 or less, 2000 or less, 1000 or less, 800 or less, 600 or less, 500 or less, 450 or less, 400 or less, 350 or less, or 300 or less. From these viewpoints, the degree of polymerization may be 100 to 5000, 200 to 4500, or 300 to 1000.

[0041] "Acrylic resin" refers to a vinyl polymer based on a methacrylic acid ester monomer. Examples of such methacrylic acid ester monomers include methyl methacrylate, ether methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, and hexyl methacrylate. Of these, methyl methacrylate is particularly preferred. Furthermore, the alkyl groups, such as propyl, butyl, pentyl, and hexyl groups, in the methacrylic acid ester monomers may be linear or branched. The resin may also be a homopolymer of a methacrylic acid ester monomer or a copolymer of multiple methacrylic acid ester monomers. Alternatively, the resin may contain monomer units derived from known vinyl compounds other than methacrylic acid esters, such as ethylene, propylene, butadiene, styrene, α-methylstyrene, acrylonitrile, and acrylic acid.

[0042] Examples of "nylon-based resins" include lactam polymers such as caprolactam and laurolactam, polymers of aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, aliphatic diamines such as hexamethylenediamine, decamethylenediamine, dodecamethylenediamine and 2,2,4- or 2,4,4-trimethylhexamethylenediamine, alicyclic diamines such as 1,3- or 1,4-bis(aminomethyl)cyclohexane and bis(p-aminocyclohexylmethane), and aromatic diamines such as m- or p-xylylenediamine, polycondensates of diamine units and dicarboxylic acid units such as aliphatic dicarboxylic acids such as adipic acid, suberic acid and sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and copolymers thereof. Specific examples of nylon resins include nylon 6, nylon 9, nylon 11, nylon 12, nylon 66, nylon 610, nylon 611, nylon 612, nylon 6T, nylon 6I, nylon MXD6, nylon 6 / 66, nylon 6 / 610, nylon 6 / 6T, and nylon 6I / 6T.

[0043] The term "polyacetal resin" refers to a crystalline polymer having an oxymethylene group as a repeating unit in the polymer chain. The polyacetal resin may be, for example, a homopolymer whose main chain is formed only of carbon-oxygen bonds, or a copolymer whose main chain also contains carbon-carbon bonds.

[0044] Examples of "polyimide-based resins" include polyimide resins, polyamideimide resins, and polyetherimide resins. Polyimide resins are resins containing repeating structural units containing imide groups, polyamideimide resins are resins containing repeating structural units containing both imide groups and amide groups, and polyetherimide resins are resins containing a combination of imide bonds and ether bonds.

[0045] The term "polybenzimidazole resin" refers to a polymer containing substituted or unsubstituted benzimidazole as a monomer unit.

[0046] The proportion of the above resin in resin (A) is preferably 50% by mass or more, more preferably 80% by mass or more, based on the total mass of resin (A). Resin (A) may also contain only the above resin. That is, the proportion of the above resin in resin (A) may be 50 to 100% by mass, or may be 80 to 100% by mass.

[0047] In one embodiment, from the viewpoint of easily ensuring the fluidity required for 3D printing using a 3D printer, the mass average molecular weight (Mw) of resin (A) is preferably 110,000 to 150,000. Furthermore, from the viewpoint of easily obtaining a 3D-modeled object with good impact resistance and heat resistance, the Mw may be 140,000 to 170,000. Two or more ABS resins with different Mws may be mixed to achieve the above-mentioned fluidity, heat resistance, impact resistance, and the like. When two or more ABS resins are mixed, it is preferable to adjust the average Mw of the mixture to be within the aforementioned range (e.g., 110,000 to 170,000). Furthermore, when using a single ABS resin, from the viewpoint of the above-mentioned fluidity, heat resistance, and impact resistance, it is particularly preferable to use an ABS resin with a Mw of 130,000 to 150,000. The Mw of resin (A) refers to a value measured using GPC, solvent: THF, measurement temperature: 40°C, and standard: polystyrene.

[0048] The proportion of resin (A) in the resin composition can be adjusted arbitrarily within the range of 60 to 93% by mass, relative to the total mass of the resin composition. In one embodiment, the proportion of resin (A) in the resin composition may be 65 to 92% by mass, or 70 to 90% by mass, relative to the total mass of the resin composition. It may also be 65 to 93% by mass, 75 to 93% by mass, 65 to 92% by mass, 75 to 92% by mass, 80 to 90% by mass, or 70 to 80% by mass.

[0049] <Plate-like particles (B)> The resin composition used in the manufacturing method of this embodiment contains 7 to 40 mass % of plate-like particles (B) relative to the total mass of the resin composition. By combining such plate-like particles (B) with the above-mentioned resin (A), it is possible to manufacture an additive manufacturing product with reduced warpage and surface irregularities.

[0050] Here, "plate-like particles" refers to particles that are thin and have an aspect ratio of 1.0 or more. Therefore, the plate-like particles may include particles other than spherical particles, such as those described as scaly particles, rod-like particles, or needle-like (fibrous) particles. In a preferred embodiment, the plate-like particles include scaly particles such as talc, clay (kaolin, bentonite), and mica. Whether the particles in the resin composition are plate-like particles can be determined, for example, by observing the particles (100 or more) contained in the resin composition according to this embodiment with an electron microscope such as an SEM and determining whether more than 50% by number of particles have a thin thickness and an aspect ratio of 1.0 or more. In one embodiment, the aspect ratio of the plate-like particles (B) may be 10 to 90, 10 to 80, or 20 to 70.

[0051] In one embodiment, the particles constituting the plate-like particles (B) (hereinafter sometimes referred to as "raw material particles") preferably have a Mohs hardness of 3 or less. "Mohs hardness" is a hardness index expressed on a scale of 1 to 10, and is a value obtained by rubbing a substance to be measured against a corresponding standard substance and evaluating the hardness relative to the standard substance based on whether scratches are caused. The standard substances, in order from soft (Mohs hardness 1) to hard (Mohs hardness 10), are 1: talc, 2: gypsum, 3: calcite, 4: fluorite, 5: apatite, 6: feldspar, 7: quartz, 8: topaz, 9: corundum, and 10: diamond. The Mohs hardness is measured by preparing two smooth plates with known Mohs hardness, sandwiching the foreign object to be measured between the two plates, and rubbing the two plates together to check for scratches on the plate surfaces. The Mohs hardness of the raw material particles of the plate-like particles (B) is more preferably 2 or less, and even more preferably 1 or less.

[0052] In one embodiment, the plate-like particles (B) are preferably particles with a low content of crystalline silica or particles that are substantially free of crystalline silica. By combining such plate-like particles (B) with the aforementioned resin (A) and adjusting the proportion of crystalline silica in the resin composition to a certain value or less, the nozzle of the 3D printer is prevented from wearing out and warping during modeling is easily suppressed. Note that "particles with a low content of crystalline silica or particles that are substantially free of crystalline silica" more specifically refers to particles in which the crystalline silica content is less than 0.2% by mass or in which crystalline silica is substantially not detected, as measured by the X-ray diffraction method described below.

[0053] The content of crystalline silica in the plate-like particles (B) can be measured by X-ray diffraction (base standard absorption correction method). Specifically, first, a qualitative analysis of free silicic acid in the plate-like particles (B) is performed using an X-ray diffraction analyzer. At this time, quartz, cristobalite, and tridymite (manufactured by the Japan Working Environment Measurement Association, a public interest incorporated association) are used as standard samples for free silicic acid analysis. Then, a quantitative analysis of crystalline silica in the plate-like particles (B) is performed by X-ray diffraction (base standard absorption correction method). The measurement conditions for the X-ray diffraction method are as follows: Measurement device: X-ray generator (for example, a desktop rotating anode X-ray generator manufactured by Rigaku Corporation, product name "Ultrax18") Target: Cu Scan angle: 5° to 60° Step width: 0.02° Measurement time: 0.6 seconds Tube voltage: 40 kV Tube current: 30 mA Divergence slit: 1.00°, scattering slit: 1.00°, receiving slit: 0.3 mm

[0054] The detection limit for the crystalline silica content in the plate-like particles (B) under the above measurement conditions is 0.1% by mass. The crystalline silica content of general talc and mica measured by the above method is about 1% by mass. The plate-like particles (B) according to the first embodiment have a lower crystalline silica content than general talc and mica. In a preferred embodiment, the crystalline silica content in the plate-like particles (B) is less than 0.2% by mass, and in a more preferred embodiment, it is 0.1% by mass or less. In a further preferred embodiment, the plate-like particles (B) are at least one particle selected from talc, mica, and clay, in which crystalline silica is not detected under the above measurement conditions.

[0055] The proportion of crystalline silica relative to the total mass of the resin composition is preferably less than 0.02% by mass. By having the proportion of crystalline silica in the resin composition less than 0.02% by mass, warping during modeling can be suppressed, and wear of the nozzle of the 3D printer can also be suppressed. From the viewpoint of more easily suppressing nozzle wear, the proportion of crystalline silica in the resin composition may be 0.015% by mass or less, or may be 0.01% by mass or less. Furthermore, it is preferable that no crystalline silica is detected when measured under the above-mentioned measurement conditions for the content of crystalline silica in the plate-like particles (B). The proportion of crystalline silica in the resin composition may be determined by heating the resin composition at 500 ° C. in a nitrogen atmosphere to incinerate it, and then measuring the proportion of crystalline silica in the resulting residue under the above-mentioned measurement conditions. Alternatively, the proportion of crystalline silica in the resin composition may be calculated from the content of crystalline silica in the plate-like particles (B).

[0056] (Average particle size (D50)) The average particle size (D50) of the plate-like particles (B) is preferably 10 μm or less. In one embodiment, the average particle size (D50) of the plate-like particles (B) is more preferably 0.1 μm to 10 μm, even more preferably 0.5 μm or more and less than 9 μm, and particularly preferably 0.5 to 8 μm. In one embodiment, the average particle size (D50) of the plate-like particles (B) may be 0.1 μm to 3 μm, 0.5 μm to 2.5 μm, 0.8 μm to 2.2 μm, 4 μm to 10 μm, 5 μm to 9 μm, or 6 μm to 8 μm. In another embodiment, the average particle size (D50) of the plate-like particles (B) is preferably 2 μm to 10 μm, more preferably 2 μm to 9 μm, and even more preferably 2 μm to 8 μm. If the average particle diameter (D50) is within the above range, the increase in elastic modulus during mixing is small, so that the filament does not break during production, and productivity is likely to be good. Furthermore, it is easy to suppress surface irregularities of the layered object. The average particle diameter (D50) of the plate-like particles (B) refers to the volume-based cumulative diameter (D50) evaluated by laser diffraction scattering. Furthermore, "volume-based cumulative diameter (D50)" means the particle diameter corresponding to the cumulative value of 50% in the volume-based cumulative particle size distribution measured by laser diffraction scattering. The cumulative particle size distribution is represented by a distribution curve with the particle diameter (μm) on the horizontal axis and the cumulative value (%) on the vertical axis.

[0057] (Surface Treatment Agent) In one embodiment, the plate-like particles (B) are treated with a surface treatment agent. The plate-like particles (B) may be treated with one or more surface treatment agents selected from the group consisting of a silane coupling agent (X) and hexamethyldisilazane (HMDS). "Treated with a surface treatment agent" means that at least a portion of the surface of the plate-like particles (B) is coated with the surface treatment agent. By treating the plate-like particles (B) with a surface treatment agent and rendering them hydrophobic, the resin composition is less likely to thicken, more likely to suppress warpage during modeling, and more likely to have good high-speed modeling properties. In the present disclosure, "high-speed modeling properties" refers to the ability to model an additively manufactured object at a modeling speed of, for example, 80 to 150 mm / s. Resin materials with poor high-speed modeling properties may experience uneven discharge at the above-mentioned modeling speeds, or may have holes or other defects in the appearance of the resulting additively manufactured object. By using particles whose surfaces have been treated with a surface treatment agent as the plate-like particles (B), it becomes easier to obtain a layered manufactured product with excellent appearance even when manufactured at high speed.

[0058] The silane coupling agent (X) is not particularly limited, but in one embodiment, silane coupling agents containing a functional group such as a vinyl group, an amino group, a styryl group, an epoxy group, or a mercapto group in the structure may be used alone or in combination of two or more.

[0059] Examples of silane coupling agents containing a vinyl group in the structure (vinyl-based silane coupling agents) include vinyltrimethoxysilane, vinyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0060] Examples of silane coupling agents containing an amino group in the structure (amino-based silane coupling agents) include N-2-(aminoethyl)-3-aminopropylmethyldimethoxylane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxylane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, etc. These may be used alone or in combination of two or more.

[0061] Examples of silane coupling agents containing an epoxy group in their structure (epoxy-based silane coupling agents) include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, etc. These may be used alone or in combination of two or more.

[0062] Examples of silane coupling agents containing a styryl group in the structure (styryl-based silane coupling agents) include p-styryltrimethoxysilane.

[0063] Examples of silane coupling agents containing a mercapto group in the structure (mercapto-based silane coupling agents) include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. These may be used alone or in combination of two or more.

[0064] In one embodiment, the silane coupling agent (X) is preferably a silane coupling agent containing an amino group or an epoxy group in its structure, and more preferably a silane coupling agent containing an epoxy group (epoxy-based silane coupling agent). In a particularly preferred embodiment, the silane coupling agent (X) may contain 3-glycidoxypropyltrimethoxysilane. It is presumed that the inclusion of plate-like particles (B) having a Mohs hardness of 3 or less and surface-treated with such a silane coupling agent (X) facilitates the development of adhesiveness derived from the functional group, preferably the epoxy group, in the silane coupling agent (X), and further reduces warpage. It is also presumed that the reaction between the carbonyl group derived from the oxidation of the resin (A) and the functional group (preferably the amino group or the epoxy group) in the silane coupling agent (X) further reduces thermal shrinkage.

[0065] In one embodiment, when the plate-like particles (B) are surface-treated with a surface treatment agent, the amount of the surface treatment agent added to the plate-like particles (B) may be 0.1 to 3% by mass, 0.1 to 2% by mass, 0.5 to 1.5% by mass, or 0.5 to 1% by mass, relative to the total mass (100% by mass) of the plate-like particles (B). By setting the proportion of the surface treatment agent within the above range, the effect of suppressing warping during molding is more easily achieved. As the plate-like particles (B) whose surfaces are treated with a surface treatment agent, it is preferable to use at least one selected from the aforementioned talc, mica, and clay having a crystalline silica content of less than 0.2% by mass, and it is more preferable to use talc and / or mica. By using such plate-like particles (B), it is possible to obtain a resin composition that does not wear out the nozzle of a 3D printer, can suppress warping during molding, and is capable of high-speed molding.

[0066] The method for treating the surfaces of the raw material particles with a surface treatment agent is not particularly limited, and a general method can be used, such as dissolving the surface treatment agent in an organic solvent such as ethanol, spraying the solution onto the raw material particles, and heating the mixture while stirring. Whether the surfaces of the plate-like particles (B) have been treated with a surface treatment agent may be determined by analyzing the surfaces of the plate-like particles (B) in the resin composition by TEM-EDX and detecting Si elements.

[0067] Commercially available products may be used as the plate-like particles (B), such as those available from Nippon Talc Co., Ltd. under the product names "FG-15," "D-1000," and "D-800."

[0068] In this embodiment, the content of the plate-like particles (B) in the resin composition, i.e., the ratio of the plate-like particles (B) to the total mass of the resin composition, is 7 to 40% by mass. The content of the plate-like particles (B) in the resin composition may be 8 to 35% by mass, or 10 to 30% by mass. It may also be 7 to 35% by mass, 7 to 25% by mass, 8 to 35% by mass, 8 to 25% by mass, 10 to 20% by mass, or 20 to 30% by mass.

[0069] <Other Components> The resin composition according to this embodiment may contain components (other components) other than the resin (A) and the plate-like particles (B) described above, as long as the effects of the present disclosure are not impaired. Examples of other components include thermoplastic resins other than the resin (A) (e.g., PLA resin, PC resin, etc.); inorganic particles other than the plate-like particles (B); polymer fillers; additives such as ultraviolet absorbers, stabilizers, antioxidants, plasticizers, colorants, tinting agents, flame retardants, antistatic agents, fluorescent brighteners, matting agents, impact strength improvers, and lubricants (fatty acid esters, higher alcohols, ethylene bis(stearic acid amide)). These may be used alone or in combination of two or more. When the resin composition contains other components, they may be blended in an amount of 2% by mass or less relative to the total mass of the resin composition.

[0070] <Physical Properties of Resin Composition> In one embodiment, from the viewpoint of being more likely to produce a resin composition that has excellent high-speed modeling properties and good warpage suppression, the MFR (220°C, 10 kg load) of the resin composition is preferably 30 g / 10 min or less, more preferably 6 g / 10 min or more and less than 30 g / 10 min, and even more preferably 8 to 28 g / 10 min. In one embodiment, the MFR (220°C, 10 kg load) of the resin composition may be in the range of 10 to 30 g / 10 min. The MFR (220°C, 10 kg load) of the resin composition can be measured, for example, using a product named "Melt Indexer G-02" manufactured by Toyo Seiki Seisakusho, Ltd., in accordance with JIS K7210.

[0071] [Method for Producing Resin Composition] The method for producing the resin composition according to this embodiment is not particularly limited as long as it achieves the effects of the present invention. For example, a method can be used in which the resin (A), the plate-like particles (B), and, if necessary, other components are mixed in a twin-screw kneader or the like, and then extruded into the desired shape to obtain a resin composition. When molding the resin composition into a filament, the kneader is preferably equipped with a strand spooler, gear pump, or the like for producing filaments. Since the resin composition according to this embodiment contains specific surface-treated plate-like particles (B), it also has good mixability with the resin (A). In one embodiment, when using a twin-screw kneader (e.g., manufactured by Shibaura Machine Co., Ltd., product name "TEM-26SX"), mixing can be performed under the following conditions: a set temperature of 200 to 220°C, a discharge rate of 30 to 40 kg / hr, and a rotation speed of 250 to 350 rpm.

[0072] In one embodiment, the method for producing a resin composition may include preparing plate-like particles (B), i.e., treating raw material particles with the above-mentioned surface treatment agent to obtain plate-like particles (B), and mixing the resin (A) and the plate-like particles (B) and extruding the mixture into a desired shape to obtain a resin composition.

[0073] [Layered Manufactured Product] An layered manufactured product according to one embodiment of the present disclosure is a layered manufactured product of a resin composition containing a resin (A) having a saturated water absorption of 0.2% or more, as measured in accordance with ASTM D570, and plate-like particles (B), wherein the content of the plate-like particles (B) in the resin composition is 7 to 40% by mass, the average particle diameter (D50) of the plate-like particles is 2 μm or more, and the arithmetic mean surface height of the layered manufactured product is less than 100 μm, and the layered manufactured product is manufactured using the above-described manufacturing method. In a preferred embodiment, the layered manufactured product is composed solely of the resin composition of this embodiment. Such layered manufactured products exhibit little warping and good appearance. Therefore, the layered manufactured product according to this embodiment can be suitably used for applications such as stationery; toys; covers for electronic devices such as smartphones; parts such as grips; educational materials, repair parts for home appliances and office equipment, various parts for automobiles, motorcycles, bicycles, etc.; building materials; plastic shaping molds, etc.

[0074] In one embodiment, when the layered object is placed on a horizontal plate, the maximum value of the gap (floating amount) between the bottom surface of the layered object and the horizontal plate is preferably less than 1 mm, and more preferably 0.3 mm or less. The floating amount can be determined by measuring the distance of the gap between the layered object and the horizontal plate with a curved ruler at a point where the bottom of the layered object is separated from the horizontal plate and floating, while the layered object is placed on the horizontal plate.

[0075] In this embodiment, the arithmetic mean height of the surface of the layered object is less than 100 μm, but in one embodiment, the arithmetic mean height of the surface of the layered object is preferably less than 40 μm, more preferably less than 30 μm, and even more preferably less than 20 μm. The arithmetic mean height of the surface of the layered object can be measured using a 3D measuring laser microscope (for example, the "LEXT OLS5100" manufactured by Evident Co., Ltd.) in accordance with ISO 25178.

[0076] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] An additively manufactured object of a resin composition including a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-like particles (B), wherein the content of the plate-like particles (B) in the resin composition is 7 to 40 mass %, the average particle diameter (D50) of the plate-like particles is 2 μm or more, and the arithmetic mean height of the surface of the additively manufactured object is less than 100 μm. [2] The additively manufactured object according to [1], wherein the arithmetic mean height of the surface of the additively manufactured object is less than 40 μm. [1] A method for producing an additively manufactured product, comprising additively manufacturing a resin composition containing a resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 and plate-like particles (B), the content of the plate-like particles (B) being 7 to 40% by mass, while maintaining the water absorption of the resin composition at less than 0.2%. [2] The manufacturing method according to [1], wherein the plate-like particles (B) contain talc. [3] The manufacturing method according to [1] or [2], wherein the average particle size (D50) of the plate-like particles (B) is 10 μm or less. [4] The manufacturing method according to any one of [1] to [3], wherein additively manufacturing while maintaining the water absorption of the resin composition at less than 0.2% comprises additively manufacturing in an atmosphere with a relative humidity of 40% or less. [5] The manufacturing method according to any one of [1] to [4], comprising drying the resin composition so that the water absorption of the resin composition is less than 0.2%. [6] The manufacturing method according to any one of [1] to [5], wherein the resin comprises one or more resins selected from the group consisting of acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylic acid ester resin, polyvinyl alcohol resin, and nylon-based resin. [7] The manufacturing method according to any one of [1] to [6], wherein the plate-like particles are treated with at least one of a silane coupling agent and HMDS. Each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the present disclosure.

[0077] The present disclosure will be explained in more detail below by showing examples, but interpretation of the present disclosure is not limited to these examples.

[0078] <Raw Materials> The following were used as resin (A). (Resin (A)) Resin (A-1): ABS resin (manufactured by Denka Company Limited, product name "GR3500", MFR (220°C, 10 kg load): 14 g / 10 min, saturated water absorption measured in accordance with ASTM D570: 0.35%) Resin (A-2): ABS resin (manufactured by Denka Company Limited, product name "GR-R-61A", MFR (220°C, 10 kg load): 71 g / 10 min, saturated water absorption measured in accordance with ASTM D570: 0.36%) Resin (A-3): Polyvinyl alcohol (manufactured by Denka Company Limited, product name "B-05", MFR (220°C, 10 kg load): 8.4 g / 10 min, saturated water absorption measured in accordance with ASTM D570: 1000% or more (water soluble)). The MFR of the resin (A) is a value measured at 220° C. under a load of 10 kg.

[0079] The following were used as the plate-like particles (B). (Plate-like particles (B)) Plate-like particles (B-1): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "P-2", average particle size (D50): 7 μm, aspect ratio: 20). Plate-like particles (B-2): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "P-2", average particle size (D50): 7 μm, aspect ratio: 20, surface-treated with 1 mass % of a silane coupling agent (3-glycidoxypropyltrimethoxysilane) relative to the total mass of the raw material particles). Plate-like particles (B-3): talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "FG-20", average particle diameter (D50): 2 μm, aspect ratio: 20, surface treated with 1% by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane) relative to the total mass of the raw material particles).

[0080] <Measurement of Crystalline Silica Content> The crystalline silica content in the plate-like particles (B) was measured under the following conditions. The crystalline silica content in each plate-like particle (B) was measured by X-ray diffraction (base standard absorption correction method). Specifically, first, the plate-like particles (B) were subjected to a qualitative analysis of free silicic acid using an X-ray diffraction analyzer. Quartz, cristobalite, and tridymite (manufactured by the Japan Working Environment Measurement Association, a public interest incorporated association) were used as standard samples for free silicic acid analysis. Then, the crystalline silica in the plate-like particles (B) was quantitatively analyzed by X-ray diffraction (base standard absorption correction method). The measurement conditions for the X-ray diffraction method were as follows: Measurement device: X-ray generator (tabletop rotating anode X-ray generator manufactured by Rigaku Corporation, product name "Ultrax18") Target: Cu Scan angle: 5° to 60° Step width: 0.02° Measurement time: 0.6 seconds Tube voltage: 40 kV Tube current: 30 mA Divergence slit: 1.00°, scattering slit: 1.00°, receiving slit: 0.3 mm

[0081] The detection limit for the crystalline silica content in the above measurement method is 0.1% by mass. Since no crystalline silica was detected in the plate-like particles (B-1) to (B-5) by the above measurement method (undetected), the crystalline silica content in these plate-like particles (B-1) to (B-5) is presumed to be 0% by mass or more and less than 0.1% by mass.

[0082] <Measurement of Changes in Water Absorption of Resin Composition> A certain amount (100 g) of filament formed from the resin composition was wound around a metal bobbin whose weight had been measured and dried at 80 ° C for 2 hours. Then, the weight change was measured over time in an environmental test chamber with controlled temperature and humidity (at 20 ° C and 30% relative humidity, at 20 ° C and 45% relative humidity, and at 20 ° C and 50% relative humidity), and the water absorption of the resin composition was calculated from the increased weight. The water absorption rate did not increase in an atmosphere of 20 ° C and 30% relative humidity, but increased by 0.1% in 3 hours at 20 ° C and 45% relative humidity, and increased by 0.1% in 1 hour at 20 ° C and 50% relative humidity. Based on these findings, the water absorption rates of the resin composition at the start of modeling and at the end of modeling were calculated.

[0083] Example 1 A twin-screw kneader (manufactured by Thermo Fisher Scientific, product name "Process 11") equipped with a monofilament production strand spooler and a gear pump was used. 67.5 parts by mass of resin (A-1), 22.5 parts by mass of resin (A-2), and 10 parts by mass of plate-like particles (B-1) were mixed and extruded at 220°C to produce a filament made of the resin composition having a diameter of 1.75 mm. The MFR (220°C, 10 kg load) of the resulting filament was measured in accordance with JIS K7210 using a Toyo Seiki Seisakusho Co., Ltd. product name "Melt Indexer G-02." Furthermore, an additive manufacturing object was manufactured using the resulting filament under the following conditions, and warpage and surface irregularities were evaluated. The results are shown in Table 1.

[0084] <Warpage evaluation of laminated object> The filament was dried at 80 ° C for 2 hours, and then placed in a PolyBox filament moisture-proof box adjusted to a relative humidity of 30% for 48 hours. The moisture-proof box was then connected to a 3D printer (manufactured by Japan 3D Printer Co., Ltd., product name "Raise3D Pro2"), and the substrate temperature was 100 ° C., nozzle temperature: 240 ° C., modeling speed: 30 mm / s, internal filling rate: 100%, and ambient temperature in the 3D printer: approximately 30 to 40 ° C. A sample plate (laminated object) for evaluation measuring 200 mm wide x 50 mm long x 4 mm thick was created using the filament. The obtained sample plate was placed on a horizontal glass plate, and the maximum value of the gap distance at the contact surface between the sample plate and the glass plate was measured with a curved ruler, and 1 mm or less was measured with a high-precision contact digital sensor GT2 (manufactured by Keyence Corporation). If the maximum value was less than 1 mm, it was considered to have passed.

[0085] <Evaluation of Surface Irregularity of Layered Object> The arithmetic mean height of the surface of the sample plate obtained in the same manner as in the warpage evaluation was measured under the following conditions, and the surface arithmetic mean height was rated as "good" if it was less than 40 μm, "passable" if it was 40 μm or more and less than 100 μm, and "unacceptable" if it was 100 μm or more. (Measurement Conditions) The surface of the sample plate was measured using a 3D measuring laser microscope ("LEXT OLS5100" manufactured by Evident Co., Ltd.) in accordance with ISO 25178.

[0086] [Examples 2 to 12 and Comparative Examples 1 to 7] Filaments were produced under the same conditions as in Example 1, except that the resin composition, drying conditions, and relative humidity in the drying box were as shown in Table 1. The MFR (220°C, 10 kg load) of the filaments in each example was measured under the same conditions as in Example 1. Warpage and surface irregularities were also evaluated under the same conditions as in Example 1. The results are shown in Tables 1 and 2.

[0087]

[0088]

[0089] As shown in Table 1, when an additive manufacturing method was used to manufacture an additive manufacturing product, warping and surface irregularities were suppressed in the additive manufacturing product. The reason for the suppression of surface irregularities is presumed to be that additive manufacturing performed while maintaining the water absorption rate of the resin composition at 0.2% or less suppresses contact between moisture and the plate-like particles, thereby suppressing the generation of bubbles caused by the reaction between moisture and the plate-like particles. On the other hand, as shown in Comparative Examples 1 to 6, when additive manufacturing was performed without drying the resin composition before starting additive manufacturing, or when additive manufacturing was performed in an atmosphere with a relative humidity of 50% after drying the resin composition, the water absorption rate of the resin composition reached 0.2% or more, resulting in warping and surface irregularities in the additive manufacturing product. These results confirm that the manufacturing method of this embodiment can manufacture additive manufacturing products with suppressed warping and surface irregularities.

[0090] The layered object of this embodiment has industrial applicability because it has reduced surface unevenness. Furthermore, the method for manufacturing a layered object of this embodiment can be used to manufacture layered objects with reduced warping and surface unevenness, even when a resin with a water absorption rate of at least a certain level is used, and therefore has industrial applicability.

Claims

1. A laminated molded article of a resin composition containing a resin (A) having a saturated water absorption rate of 0.2% or more measured in accordance with ASTM D570 and plate-like particles (B), wherein the content of the plate-like particles (B) in the resin composition is 7 to 40% by mass, the average particle diameter (D50) of the plate-like particles is 2 μm or more, and the surface arithmetic mean height of the laminated molded article is less than 100 μm.

2. The laminated molded article according to claim 1, wherein the surface arithmetic mean height of the laminated molded article is less than 40 μm.

3. A method for manufacturing a laminated molded article, comprising laminating a resin composition containing a resin (A) having a saturated water absorption rate of 0.2% or more measured in accordance with ASTM D570 and plate-like particles (B), wherein the content of the plate-like particles (B) is 7 to 40% by mass, while maintaining the water absorption rate of the resin composition at less than 0.2%.

4. The method for manufacturing a laminated molded article according to claim 3, wherein the average particle diameter (D50) of the plate-like particles (B) is 10 μm or less.

5. The method for manufacturing a laminated molded article according to claim 3 or 4, wherein laminating while maintaining the water absorption rate of the resin composition at less than 0.2% includes laminating in an atmosphere having a relative humidity of 40% or less.

6. The method for manufacturing a laminated molded article according to claim 3 or 4, including drying the resin composition so that the water absorption rate of the resin composition becomes less than 0.2%.

7. The method for manufacturing a laminated molded article according to claim 3 or 4, wherein the resin contains one or more resins selected from the group consisting of acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylic ester resin, polyvinyl alcohol resin, and nylon-based resin.

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