Resin composition and laminated molded article

Abstract

Provided is a resin composition capable of producing a laminated molded article in which warpage and surface unevenness are suppressed even when a resin having a water absorption rate of a certain level or higher is used. This resin composition comprises a resin (A) having a saturated water absorption rate 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) is 7-40 mass%, and the average particle diameter (D50) of the plate-shaped particles is less than 2 μm.

Description

Resin composition and laminated object

[0001] The present disclosure relates to a resin composition and an additive manufacturing method.

[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. The filaments are melted and extruded from the nozzle of the 3D printer, and then laminated to form the desired shape. Filaments used in FDM 3D printers are primarily polylactic acid resin (PLA resin) and acrylonitrile-styrene-butadiene resin (ABS resin). While ABS resin is easy to use to create additively manufactured objects with excellent heat resistance and has good post-processing properties, 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, when a water-absorbent resin such as ABS is used, unlike a non-water-absorbent resin such as polypropylene resin, if the resin absorbs water after a certain period of time after drying, and flat particles such as talc are added to suppress warping, foaming occurs during molding, causing surface irregularities, and it has been found that this is not suitable for practical use.

[0005] International Publication No. 2021 / 060278

[0006] Therefore, an object of the present disclosure is to provide a resin composition that can be used to produce layered objects with reduced warping and surface irregularities, even when using a resin with a saturated water absorption rate of a certain level or higher.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by blending a specific amount of plate-like particles having an average particle size of a certain amount or less with a resin having a saturated water absorption of a certain amount or more, and have thus completed the present invention. That is, the present disclosure includes the following aspects: [1] A resin composition comprising 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 mass %, and the average particle size (D50) of the plate-like particles is less than 2 μm.

[0008] According to the present disclosure, it is possible to provide a resin composition that can produce a layered object with reduced warping and surface irregularities, even when a resin having a water absorption rate of a certain level or higher is used.

[0009] 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.

[0010] [Resin Composition] The resin composition of this embodiment contains 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 mass %, and the average particle diameter (D50) of the plate-like particles being less than 2 μm. The resin composition of this embodiment makes it possible to produce an additive manufacturing product with reduced warpage and surface unevenness.

[0011] 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 to, for example, a layered object warping of 1 mm or more. When this phenomenon occurs, problems arise, such as difficulty in obtaining a layered object of the desired shape, or the layered object coming into contact with the nozzle of the 3D printer, making further manufacturing impossible. The manufacturing method according to this embodiment can suppress warping during manufacturing, thereby obtaining a layered object of the desired shape. It can also prevent problems during manufacturing caused by warping. In this specification, "layered object" refers to a layered object in the middle of being manufactured.

[0012] Use of the resin composition of this embodiment not only suppresses warpage of the layered object, but also suppresses the occurrence of surface irregularities in the layered object. Here, "occurrence of surface irregularities" refers to, for example, using the surface arithmetic mean height of a layered object molded using the resin composition as an indicator, that the surface arithmetic mean height of the layered object is 40 μm or more. The occurrence of surface irregularities reduces the impact strength of the resulting layered object, making it unsuitable for practical use. Use of the resin composition of this embodiment suppresses the occurrence of surface irregularities, allowing the production of layered objects with excellent impact strength. The surface arithmetic mean height of the layered object can be measured using a 3D measuring laser microscope (e.g., "LEXT OLS5100" manufactured by Evident Co., Ltd.) in accordance with ISO 25178.

[0013] 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 and has a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570. By combining resin (A) with the plate-like particles (B) described below, a resin composition can be obtained that can produce an additive manufacturing object with reduced warpage and surface irregularities. The saturated water absorption of resin (A) as measured in accordance with ASTM D570 is preferably 0.2% to 0.6%, more preferably 0.2% to 0.5%, and even more preferably 0.2% to 0.4%.

[0014] Examples of the resin (A) having a saturated water absorption of 0.2% or more as measured in accordance with ASTM D570 include styrene-based resins, nylon-based resins, polyacetal-based resins, polyimide-based resins, polybenzimidazole-based resins, and acrylic-based resins.

[0015] "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.

[0016] 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).

[0017] 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-styrene-acrylic acid ester copolymer (ASA resin), acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS resin), and acrylonitrile-(ethylene-propylene-diene rubber)-styrene copolymer (AES resin). These rubber component-containing styrene-based resins can be used alone or in combination of two or more types as the resin (A).

[0018] 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.

[0019] (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.

[0020] 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.

[0021] 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.

[0022] "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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The term "polybenzimidazole resin" refers to a polymer containing substituted or unsubstituted benzimidazole as a monomer unit.

[0027] 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.

[0028] 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 90,000 to 140,000. Furthermore, from the viewpoint of easily obtaining a 3D-modeled object with good impact resistance and heat resistance, the Mw may be 100,000 to 150,000. Two or more ABS resins with different Mws may be mixed to achieve the fluidity, heat resistance, impact resistance, and other properties. 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., 100,000 to 140,000). Furthermore, when using a single ABS resin, from the viewpoint of the aforementioned fluidity, heat resistance, and impact resistance, it is particularly preferable to use an ABS resin with a Mw of 100,000 to 140,000. The Mw of resin (A) refers to a value measured using GPC, solvent: THF, measurement temperature: 40°C, and standard: polystyrene.

[0029] 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.

[0030] <Plate-Like Particles (B)> The resin composition according to this embodiment contains 7 to 40 mass % of plate-like particles (B) having an average particle diameter (D50) of less than 2 μm, based on the total mass of the resin composition. By combining such plate-like particles (B) with the resin (A), a resin composition is obtained that can be used to produce an additive manufacturing product with reduced warpage and surface irregularities.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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

[0035] 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.

[0036] 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).

[0037] (Average particle size (D50)) The average particle size (D50) of the plate-like particles (B) according to this embodiment is less than 2 μm. In one embodiment, the average particle size (D50) of the plate-like particles (B) is preferably 0.5 μm to 1.8 μm, more preferably 0.5 μm or more and less than 1.5 μm, even more preferably 0.5 to 1.3 μm, even more preferably 0.5 μm or more and less than 1 μm, and particularly preferably 0.5 μm to 0.8 μm. In one embodiment, the average particle size (D50) of the plate-like particles (B) may be 0.1 μm or more and less than 2 μm, 0.1 μm to 1.8 μm, 0.1 μm or more and less than 1.5 μm, 0.1 μm or more and less than 1.3 μm, 0.1 μm or more and less than 1 μm, or 0.1 μm to 0.8 μm. If the average particle diameter (D50) is within the above range, the increase in storage modulus during mixing is small, so that filaments do not break during production, and productivity is likely to be good. Furthermore, it is possible to produce layered objects with reduced surface irregularities. 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, the "volume-based cumulative diameter (D50)" refers to the particle diameter corresponding to a 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 particle diameter (μm) on the horizontal axis and cumulative value (%) on the vertical axis.

[0038] (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. Treating the plate-like particles (B) with a surface treatment agent and rendering them hydrophobic improves particle dispersibility, making it easier to suppress warpage during modeling and also improving high-speed modeling capabilities. In the present disclosure, "high-speed modeling capabilities" 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 capabilities may experience uneven discharge at the above-mentioned modeling speeds, or may result in 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Examples of silane coupling agents containing a styryl group in the structure (styryl-based silane coupling agents) include p-styryltrimethoxysilane.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The plate-like particles (B) may be commercially available products, such as those manufactured by Nippon Talc Co., Ltd. under the product names "FG-15," "D-1000," and "D-800."

[0049] 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.

[0050] <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 (e.g., fatty acid esters, higher alcohols, ethylene bis(stearic acid amide), etc.). 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.

[0051] <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.

[0052] [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.

[0053] 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.

[0054] [Method for Manufacturing an Additive Manufacturing Product] A method for manufacturing an additive manufacturing product according to one embodiment of the present disclosure includes, as a raw resin, a resin composition according to the present embodiment, which comprises 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 10 to 30% by mass, and the average particle diameter (D50) of the plate-like particles being less than 2 μm. In a preferred embodiment, the raw resin is composed solely of the resin composition according to the present embodiment. The manufacturing method according to the present embodiment includes melting the resin composition and extruding the molten resin composition through a nozzle to form an additive manufacturing product. The manufacturing method according to the present embodiment is preferably a method for manufacturing an additive manufacturing product using an FDM 3D printer. When the resin composition according to the present embodiment is used as a raw resin for an FDM 3D printer, it is formed into a filament.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] [Layered Object] The layered object according to this embodiment is formed using the resin composition described above. That is, the layered object according to this embodiment contains the resin composition described above. In a preferred embodiment, the layered object is composed solely of the resin composition according to this embodiment. Such layered object has little warping, reduced surface irregularities, and a good appearance. Therefore, the layered object 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.

[0064] In one embodiment, the warpage of the layered object is preferably less than 1 mm, and more preferably 0.3 mm or less. The warpage of the layered object refers to the maximum gap (amount of lift) between the bottom surface of the layered object and a horizontal plate when the layered object (e.g., an evaluation sample plate measuring 200 mm wide x 50 mm long x 4 mm thick) is placed on the horizontal plate. The warpage 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 lifted away from the horizontal plate while the layered object is resting on the horizontal plate.

[0065] In one embodiment, the arithmetic mean height of the surface of the layered-modeled article 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-modeled article can be measured by measuring the surface of the layered-modeled article using a 3D measuring laser microscope (for example, "LEXT OLS5100" manufactured by Evident Co., Ltd.) in accordance with ISO 25178.

[0066] Another embodiment of the present disclosure is a use of the aforementioned resin composition as a resin raw material (filament) for an additively shaped object manufactured using a 3D printer, or a method of using the resin composition. A method of using the resin composition according to this embodiment as a resin raw material (filament) for a 3D printer includes, for example, obtaining a resin composition by the aforementioned method of manufacturing a resin composition, supplying the resin composition to a 3D printer, and extruding the resin composition from a nozzle while melting it to form an additively shaped object.

[0067] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] A resin composition comprising 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 mass %, and the average particle diameter (D50) of the plate-like particles is less than 2 μm. [2] The manufacturing method according to [1], wherein the plate-like particles comprise talc. [3] The manufacturing method according to [1] or [2], which is for manufacturing an additive manufacturing product. [4] The manufacturing method according to any one of [1] to [3], wherein the average particle diameter (D50) of the plate-like particles is 0.5 μm to 1.8 μm. [5] The manufacturing method according to any one of [1] to [4], wherein the plate-like particles are treated with at least one of a silane coupling agent and HMDS. [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, and nylon-based resin. [7] An additive manufacturing method according to any one of [1] to [6], wherein the resin comprises the resin composition according to any one of [1] to [6]. The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the present disclosure.

[0068] 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.

[0069] <Raw Materials> The following were used as resin (A). (Resin (A)) Resin (A-1): ABS resin (manufactured by Denka Co., Ltd., 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 Co., Ltd., product name "GR-R-61A", MFR (220°C, 10 kg load): 74 g / 10 min, saturated water absorption measured in accordance with ASTM D570: 0.36%). The MFR of resin (A) is a value measured at 220°C and 10 kg load.

[0070] (Plate-like particles (B)) The following raw material particles for each plate-like particle (B) were used. The raw material particles were surface-treated with 1% by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane) based on the total mass of the raw material particles. (Raw material particles) Plate-like particles (B-1): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "D-800", average particle size (D50): 0.8 μm, aspect ratio: 20) Plate-like particles (B-2): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "D-1000", average particle size (D50): 1 μm, aspect ratio: 20) Plate-like particles (B-3): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "FG-15", average particle size (D50): 1.5 μm, aspect ratio: 20) Plate-like particles (B-4): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "FG-20", average particle size (D50): 2 μm, aspect ratio: 20) Plate-like particles (B-5): Talc (Mohs hardness: 1, manufactured by Nippon Talc Co., Ltd., product name "P-2", average particle diameter (D50): 7 μm, aspect ratio: 20)

[0071] <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

[0072] 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.

[0073] 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 mixed with 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). The mixture was mixed at 220°C and then extruded 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, surface irregularities, and appearance were evaluated. The results are shown in Table 1.

[0074] <Warpage Evaluation of Layered-Modeled Objects> The warpage of layered-modeled objects was measured under the following conditions. Warpage of less than 1 mm was deemed acceptable. (Measurement Conditions) The filament was dried at 80°C for 2 hours and then placed in an environmental test chamber at 50% relative humidity and 25°C for 48 hours. Subsequently, using the filament and a 3D printer (manufactured by Japan 3D Printer Co., Ltd., product name "Raise3D Pro2"), an evaluation sample plate (layered-modeled object) measuring 200 mm wide x 50 mm long x 4 mm thick was produced under the following conditions: substrate temperature: 100°C, nozzle temperature: 240°C, modeling speed: 30 mm / s, internal filling rate: 100%, and ambient temperature within the 3D printer: approximately 30-40°C. The resulting sample plate was placed on a horizontal glass plate, and the maximum gap distance between the sample plate and the glass plate was measured with a curved ruler. Measurements of 1 mm or less were performed using a high-precision contact digital sensor GT2 (manufactured by Keyence Corporation).

[0075] <Evaluation of Surface Irregularities of Layered Objects> The arithmetic mean height of the surface of each sample plate obtained in the same manner as in the warpage evaluation was measured under the following conditions, and a surface arithmetic mean height of less than 40 μm was deemed to have passed. (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.

[0076] <Appearance evaluation of layered object> The appearance of the sample plates obtained in the same manner as in the warpage evaluation was evaluated visually using an optical microscope based on the following criteria: (Evaluation criteria) A: No color unevenness or streaks are observed on the surface. B: No streaks are observed on the surface, but some color unevenness is present. C: Color unevenness and streaks are present on the surface.

[0077] [Examples 2 to 11 and Comparative Examples 1 to 6] Filaments were produced under the same conditions as in Example 1, except that the resin compositions were as shown in Table 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.

[0078]

[0079]

[0080] As shown in Table 1, when a resin composition satisfying the configuration of this embodiment was used to produce an additive manufacturing product using a 3D printer, warping and surface irregularities in the additive manufacturing product were suppressed, and the appearance was also practical. On the other hand, the resin compositions of Comparative Examples 1 to 6, which contained plate-like particles (B) having an average particle size (D50) of a certain level or greater, resulted in additive manufacturing products with significant warping and surface irregularities, resulting in an appearance that was not practical. These results demonstrate that even resin compositions containing 10% or 20% by mass of plate-like particles (B) cannot solve the problems described herein when plate-like particles (B) having an average particle size (D50) of 2 μm or greater are used. These results confirm that the resin composition according to this embodiment suppresses warping and surface irregularities in additive manufacturing products.

[0081] The layered object of this embodiment has industrial applicability because the surface irregularities are suppressed.

Claims

1. A resin composition comprising 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, and the average particle diameter (D50) of the plate-like particles is less than 2 μm.

2. The resin composition according to claim 1, wherein the plate-like particles contain talc.

3. The resin composition according to claim 1 or 2, which is for manufacturing a laminated molded article.

4. The resin composition according to claim 1 or 2, wherein the average particle diameter (D50) of the plate-like particles is 0.5 μm to 1.8 μm.

5. The resin composition according to claim 1 or 2, wherein the plate-like particles are treated with at least one of a silane coupling agent and HMDS.

6. The resin composition according to claim 1 or 2, wherein the resin contains one or more resins selected from the group consisting of acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylic ester resin, and nylon-based resin.

7. A laminated molded article comprising the resin composition according to claim 1 or 2.

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