Method for manufacturing 3D printed article by means of fused filament fabrication, and filament for method for manufacturing 3D printed article by means of fused filament fabrication

Abstract

The present invention provides a method for manufacturing a 3D printed article, whereby a 3D printed article having higher rigidity and a smaller variation in mechanical properties can be manufactured.　Provided is a method for manufacturing a 3D printed article by means of fused filament fabrication using a filament containing a thermoplastic resin, wherein: the thermoplastic resin contains 55 to 100 mass% of a liquid crystalline resin in the thermoplastic resin as a whole; the difference (Tm2 - Tc) between the melting point Tm2 of the filament measured by differential scanning calorimetry and the crystallization temperature Tc is 25°C to 60°C; and the printing speed, which is the relative movement speed between a stage and a nozzle part of a 3D printing device, is controlled to be faster than 35 mm / sec and slower than 1000 mm / sec.

Description

Method for manufacturing three-dimensional objects by filament melting method and filament for manufacturing three-dimensional objects by filament melting method

[0001] The present disclosure relates to a method for manufacturing a three-dimensional object by filament fusion manufacturing and a filament for manufacturing a three-dimensional object by filament fusion manufacturing.

[0002] Liquid crystal polymers (LCPs) have high rigidity and elasticity, as well as excellent heat resistance, impact resistance, and chemical resistance, and are therefore widely used in a variety of fields. In recent years, 3D printing technologies such as fused filament fabrication (FFF) have made it possible to manufacture objects with more complex shapes without using molds or large-scale melting equipment, and the application of LCPs to 3D printing technologies has been considered. However, LCPs have properties that make them unsuitable for application to 3D printing technologies, such as a fast solidification rate and transparency to light such as lasers.

[0003] Patent Document 1 describes a resin composition for three-dimensional modeling using an FFF (FDM) method, which is characterized in that the thermoplastic resin contains a liquid crystalline resin and the content of the liquid crystalline resin in the thermoplastic resin is 0.5 to 40 mass %. Patent Document 2 describes the use of filamentous units formed from a polymer composition containing a thermotropic liquid crystalline polymer and having a predetermined minimum thickness in an additive manufacturing method.

[0004] Japanese Patent Application Laid-Open No. 2018-123263 Japanese Patent Application Laid-Open No. 2021-529685

[0005] The resin composition for three-dimensional modeling described in Patent Document 1 is a thermoplastic resin whose main component is a crystalline resin or an amorphous resin whose properties differ from those of LCP, and Patent Document 1 does not describe three-dimensional modeling of a thermoplastic resin containing LCP as a main component. Furthermore, Patent Document 2 describes improving the mechanical properties of the resulting object by adjusting the minimum thickness of the filamentous units, but does not describe improving the properties of the resulting object by adjusting the physical properties of the LCP or the manufacturing conditions of the additive manufacturing method. The present disclosure aims to provide a method for manufacturing a three-dimensional object using a filament melt manufacturing process, and a filament, which can produce three-dimensional objects with higher rigidity and less variation in mechanical properties.

[0006] The present disclosure includes the following aspects: A method for manufacturing a three-dimensional object by a filament melting process using a filament containing a thermoplastic resin, wherein the thermoplastic resin contains 55 to 100 mass % of a liquid crystalline resin in the entire thermoplastic resin, the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is 25 to 60°C, and the manufacturing method includes controlling a modeling speed, which is the relative movement speed between a nozzle unit and a stage of a three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec.

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a three-dimensional object and a filament that can manufacture a three-dimensional object with higher rigidity and less variation in mechanical properties.

[0008] 1 shows the relationship between the tensile modulus and the maximum stress when the building speed is changed to 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec using the same type of filament as in Example 1. Also shown are photographs (10x magnification) of the surfaces of three-dimensional objects obtained by changing the building speed to 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec using the same type of filament as in Example 1. From left to right, the photographs show test pieces for building speeds of 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec.

[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] [Method of Manufacturing a Three-Dimensional Model by Filament Melt Manufacturing] One embodiment of the present disclosure relates to a method of manufacturing a three-dimensional model by filament melt manufacturing. According to this embodiment, a method of manufacturing a three-dimensional model by filament melt manufacturing using a filament containing a thermoplastic resin includes: the thermoplastic resin contains 55 to 100 mass % of a liquid crystalline resin in the entire thermoplastic resin; the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured by a differential scanning calorimeter is 25 to 60°C; and controlling the modeling speed, which is the relative movement speed between the nozzle unit and the stage of the three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec. The "filament melt manufacturing" is a type of additive manufacturing method in which a thermoplastic filament is melted by heat and layered to produce a model. The term "filament" refers to a thermoplastic resin softened by heating, extruded into a string or thread-like shape (strand), and then solidified. Due to the properties of liquid crystal polymers, liquid crystal resins have a fast solidification rate. Therefore, when molten filaments are layered in a filament melting process, the layer that was previously layered tends to solidify. Layering a molten filament on a solidified layer can result in insufficient bonding between the print lines and reduced rigidity. Therefore, liquid crystal resins have properties that make them unsuitable for the filament melting process. To solve this problem, the inventors attempted to increase the nozzle movement speed so that the next layer could be layered before the previously layered layer solidified, thereby improving the bonding between the print lines. However, they found that if the nozzle movement speed is too fast, the print lines would collapse, preventing the model from being built, or even if the model was built, the print lines would become distorted, resulting in poor structure properties, making it difficult to obtain a structure with the desired characteristics. Furthermore, even if sufficient bonding between the print lines was achieved, the shear rate could be slow, resulting in low molecular orientation, which would reduce the rigidity (tensile modulus) of the resulting structure.The present inventors conducted extensive research and discovered that the rigidity of the resulting structure can be increased by controlling the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament within a predetermined range and the modeling speed, which is the relative movement speed between the nozzle and the stage of the three-dimensional modeling device, within a predetermined range. Furthermore, it was found that this method can reduce the variation in the mechanical properties of the resulting structure. The method for producing a three-dimensionally molded object disclosed herein can produce a three-dimensionally molded object by further improving the molecular orientation of the liquid crystalline resin, thereby producing a three-dimensionally molded object with higher rigidity and less variation in mechanical properties. Furthermore, the high modeling speed reduces the modeling time, increases the production speed of the object, and improves productivity.

[0011] <Filament> In this embodiment, the filament contains a thermoplastic resin. In one embodiment, the content of the thermoplastic resin in the filament may be 50 to 100% by mass, 55 to 100% by mass, 60 to 100% by mass, or 70 to 100% by mass relative to the total amount (100% by mass) of the filament. The thermoplastic resin contains 55 to 100% by mass of liquid crystalline resin relative to the total amount (100% by mass) of the thermoplastic resin. When the filament contains the liquid crystalline resin in the above-mentioned range, the properties of the liquid crystalline resin are more strongly exhibited, resulting in a three-dimensionally shaped object with superior mechanical properties. In one embodiment, the thermoplastic resin preferably contains 60 to 100% by mass of liquid crystalline resin relative to the total amount (100% by mass) of the thermoplastic resin, more preferably 70 to 100% by mass of liquid crystalline resin, even more preferably 80 to 100% by mass of liquid crystalline resin, and particularly preferably 90 to 100% by mass of liquid crystalline resin. In one embodiment, the entire thermoplastic resin (100% by mass) may be a thermoplastic liquid crystalline resin, i.e., the filaments may be made of a thermoplastic liquid crystalline resin. The thermoplastic resin may contain a thermoplastic resin other than the liquid crystalline resin. The type of thermoplastic resin that can be contained other than the liquid crystalline resin is not particularly limited, and may be any thermoplastic resin used in the filament melt manufacturing method, such as polylactic acid (PLA), acrylonitrile butadiene styrene copolymer (ABS), nylon, polypropylene, polycarbonate, polyarylate, polyetherimide, polyaryletherketone, etc. The inclusion of a thermoplastic resin other than the liquid crystalline resin slows the solidification rate and tends to improve adhesion at the lamination interface. The content of the thermoplastic resin other than the liquid crystalline resin is preferably 40% by mass or less, more preferably 0 to 30% by mass, even more preferably 5 to 25% by mass, and particularly preferably 5 to 20% by mass, of the entire thermoplastic resin (100% by mass). In one embodiment, the content of the liquid crystalline resin in the filament may be 50 to 100% by mass, 55 to 100% by mass, 60 to 100% by mass, or 70 to 100% by mass, based on the total amount of the filament (100% by mass).

[0012] (Resin composition) In order to reduce the shrinkage rate and linear expansion coefficient of the molded object, various fibrous, powdery, and plate-shaped inorganic and organic fillers can be blended into the thermoplastic resin. Examples of fibrous fillers include inorganic fibrous materials such as glass fiber, milled glass fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, silicate fibers such as wollastonite, magnesium sulfate fiber, aluminum borate fiber, and metal fibrous materials such as stainless steel, aluminum, titanium, copper, and brass. A particularly representative fibrous filler is glass fiber. High-melting point organic fibrous materials such as polyamide, fluororesin, polyester resin, and acrylic resin can also be used. Examples of powdery fillers include carbon black, graphite, silica, quartz powder, glass beads, glass balloons, glass powder, silicates such as calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite; metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony trioxide, and alumina; metal carbonates such as calcium carbonate and magnesium carbonate; metal sulfates such as calcium sulfate and barium sulfate; and ferrite, silicon carbide, silicon nitride, boron nitride, and various metal powders. Examples of plate-like fillers include mica, glass flakes, talc, and various metal foils. These inorganic and organic fillers can be used alone or in combination. The filler content can be, for example, 0 to 100 parts by weight per 100 parts by weight of the thermoplastic resin, and may be, for example, 0 to 80 parts by weight, 5 to 75 parts by weight, 10 to 50 parts by weight, or 20 to 40 parts by weight. The resin composition may also contain other additives such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, pigments, and crystal nucleating agents.

[0013] (Liquid Crystalline Resin) Liquid crystalline resins have high rigidity and elasticity, as well as excellent heat resistance, impact resistance, and chemical resistance, and are therefore widely used in various fields. However, no liquid crystalline resins suitable for 3D printers are known. The term "liquid crystallinity" refers to the ability to form an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using crossed polarizers. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope to observe a molten sample placed on a Leitz hot stage at 40x magnification under a nitrogen atmosphere. When examined between crossed polarizers, liquid crystalline resins typically transmit polarized light, even when in a molten, stationary state, demonstrating optical anisotropy.

[0014] In one embodiment, the liquid crystalline resin preferably contains at least one selected from liquid crystalline polyesters and liquid crystalline polyesteramides. The liquid crystalline polyesters and liquid crystalline polyesteramides are not particularly limited, but are preferably aromatic polyesters or aromatic polyesteramides, more preferably at least one resin selected from wholly aromatic polyesters and wholly aromatic polyesteramides, and even more preferably aromatic polyesters or aromatic polyesteramides having, as a constituent component, a structural unit derived from at least one selected from the group consisting of aromatic hydroxycarboxylic acids and their derivatives. Examples of aromatic hydroxycarboxylic acid derivatives include alkyl esters (e.g., having 1 to 4 carbon atoms), halides, and acylates. Polyesters partially containing aromatic polyesters or aromatic polyesteramides in the same molecular chain can also be used. By including the liquid crystalline resin in the thermoplastic resin, the molecular orientation of the liquid crystalline resin can be further improved, enabling the production of three-dimensional objects in a filament melt manufacturing process.

[0015] As the aromatic polyester or aromatic polyester amide, an aromatic polyester or aromatic polyester amide having an aromatic hydroxycarboxylic acid as a constituent is particularly preferred.

[0016] More specifically, the aromatic polyesters or aromatic polyesteramides include: (1) polyesters mainly composed of one or more aromatic hydroxycarboxylic acids and their derivatives; (2) polyesters mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives, and (b) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives; (3) polyesters mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives, (b) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives, and (c) one or more aromatic diols, alicyclic diols, aliphatic diols, and their derivatives; (4) polyesteramides mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives, (b) one or more aromatic hydroxyamines, aromatic diamines, and their derivatives, and (c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives; (5) Examples include polyesteramides primarily composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives, (b) one or more aromatic hydroxyamines, aromatic diamines, and their derivatives, (c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives, and (d) one or more aromatic diols, alicyclic diols, aliphatic diols, and their derivatives. Furthermore, a molecular weight modifier may be used in combination with the above components, if necessary. Examples of the "derivatives" in (1) to (5) above include alkyl esters (e.g., having 1 to 4 carbon atoms), halides, acylation products, etc.

[0017] Preferred specific examples of compounds (monomers) constituting the liquid crystalline polyester and the liquid crystalline polyesteramide include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, aromatic diols such as 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, compounds represented by the following general formula (I) and compounds represented by the following general formula (II), aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and compounds represented by the following general formula (III), and aromatic amines such as 4-aminophenol, 1,4-phenylenediamine and N-acetyl-p-aminophenol. (X: alkylene (C １ ~C ４ ), alkylidene, —O—, —SO—, —SO ２ is a group selected from —, —S—, and —CO—. (Y:-(CH ２ ) ｎ -(n=1 to 4) and -O(CH ２ ) ｎ O- (n = 1 to 4).

[0018] The method for producing liquid crystalline polyesters and liquid crystalline polyesteramides is not particularly limited, and they can be produced by known methods such as direct polymerization or transesterification using the above-mentioned monomer compounds (or monomer mixtures). Usually, melt polymerization, solution polymerization, slurry polymerization, solid-phase polymerization, or a combination of two or more of these is used, and melt polymerization or a combination of melt polymerization and solid-phase polymerization is preferably used. When the compound has the ability to form an ester, it may be used in polymerization as is, or it may be modified from a precursor to a derivative having the ability to form an ester using an acylating agent or the like in the pre-polymerization stage. Examples of the acylating agent include carboxylic anhydrides such as acetic anhydride.

[0019] Various catalysts can be used in the polymerization. Typical usable catalysts include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedionato)cobalt(III), and organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine. The amount of catalyst used is generally about 0.001 to 1 mass % relative to the total weight of the monomers, and preferably about 0.01 to 0.2 mass %.

[0020] Various fibrous, granular, or plate-like inorganic and organic fillers can be blended into the liquid crystalline resin during the manufacturing process. Specific examples and amounts of fillers include those similar to those of the fillers that may be contained in the filaments. The amount of filler can be, for example, 0 to 100 parts by mass, such as 0 to 80 parts by mass, 5 to 75 parts by mass, or 10 to 50 parts by mass, per 100 parts by mass of the liquid crystalline resin. Furthermore, the liquid crystalline resin may contain additives such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, pigments, and crystal nucleating agents as other components.

[0021] (Difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament) In this embodiment, the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is 25 to 60°C. When Tm2 - Tc is in the above-mentioned range, the solidification speed during modeling falls within a suitable range, making it possible to perform three-dimensional modeling at high modeling speeds using a filament containing a liquid crystalline resin by a filament melting method, and to produce three-dimensional objects with improved molecular orientation. In this embodiment, the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter are determined as follows. According to a method based on JIS K-7121 (1999), a differential scanning calorimeter is used to measure the peak top temperature (melting point Tm1) of the endothermic peak observed when heated from room temperature at a heating rate of 20°C / min (1st RUN), and then the sample is held at a temperature of (melting point Tm1 + 40)°C for 2 minutes, and then cooled to room temperature at a heating rate of 20°C / min. The peak top temperature of the exothermic peak observed when the sample is then heated again from room temperature at a heating rate of 20°C / min is taken as the melting point Tm2.

[0022] In one embodiment, the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured by a differential scanning calorimeter is preferably 30 to 60°C, more preferably 30 to 55°C, even more preferably 30 to 50°C, and particularly preferably 30 to 45°C. In one embodiment, the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured by a differential scanning calorimeter may be 40 to 60°C. The method for adjusting the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament to 25 to 60°C is not limited, and can be performed by, for example, the following method. (1) By increasing the content of structural units derived from aromatic hydroxycarboxylic acids and derivatives thereof in the liquid crystalline resin (for example, 50% by mass or more relative to 100% by mass of all monomers), the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc can be adjusted to a large value. By reducing the content of structural units derived from aromatic hydroxycarboxylic acids and their derivatives (for example, 0.1 to 3.0% by mass relative to 100% by mass of all monomers), the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc) can be adjusted to a small value. (2) By blending a thermoplastic resin other than the liquid crystalline resin, the melting point Tm2 and the crystallization temperature Tc can be adjusted, and the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc) can be adjusted to 25 to 60°C. (3) By adding a certain amount of a monomer having a kink structure to the filament, the crystallization temperature Tc can be lowered, thereby adjusting the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc). A kink structure refers to a monomer that changes the molecular chain direction (the direction in which monomers are connected) in a liquid crystalline polymer. Examples of monomers having a kink structure include 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 7-hydroxy-2-naphthoic acid, 6-hydroxy-1-naphthoic acid, 6-hydroxy-5-methyl-2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid, 6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6-hydroxy-5,7-dichloro-2-naphthoic acid, and isophthalic acid.In this case, the content of the monomer having a kink structure is preferably 10 to 70% by mass, more preferably 20 to 50% by mass, relative to the total monomers (100% by mass), from the viewpoint of easily adjusting the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc) to a range of 25 to 60 ° C. (4) When the filament contains a polymer that can be transesterified, such as polycarbonate, the crystallization temperature Tc can be lowered by transesterification. Therefore, when the crystallization temperature Tc is high, the crystallization temperature Tc can be adjusted lower by mixing a certain amount of a polymer that can be transesterified, and the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc) can be adjusted. In this case, the content of the polymer that can be transesterified is preferably less than 30% by mass, more preferably 0 to 25% by mass, relative to the total thermoplastic resin (100% by mass), from the viewpoint of easily adjusting the difference between the melting point Tm2 and the crystallization temperature Tc (Tm2 - Tc) to a range of 25 to 60 ° C.

[0023] In one embodiment, the melting point Tm2 of the filament measured with a differential scanning calorimeter is preferably 250 to 400°C, more preferably 260 to 380°C, and even more preferably 280 to 360°C. By setting the melting point Tm2 to 250 to 400°C, the heat resistance of the three-dimensionally shaped object can be further improved. In one embodiment, the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is preferably 200 to 400°C, more preferably 210 to 350°C, and even more preferably 220 to 330°C. By setting the crystallization temperature Tc to 200 to 400°C, the heat resistance of the three-dimensionally shaped object can be further improved.

[0024] (Filament Diameter) In one embodiment, the filament diameter is preferably 0.5 to 3.0 mm, more preferably 0.5 to 2.5 mm, even more preferably 1.0 to 2.5 mm, and particularly preferably 1.0 to 2.0 mm. By setting the filament diameter within the above range, it can be used as a modeling material in a commercially available three-dimensional modeling device to easily produce a three-dimensional model with improved molecular orientation of the liquid crystalline resin. The "filament diameter" refers to the average diameter of the solidified filament cross section. Specifically, it refers to the arithmetic mean value obtained by taking a 5-m filament, randomly selecting 20 locations, measuring the diameters (or the longest linear distances in the cross section) of the filament to three decimal places using a micrometer, and rounding the resulting value to the nearest whole number. The filament diameter can be adjusted, for example, by cooling and solidifying the extruded strand with water, and then adjusting the winding speed when winding it on a filament winder to obtain the desired diameter. In one embodiment, the filament can be wound around a core material to form a wound body. By making it into a winding body, it becomes easier to attach to commercially available 3D printers that use the filament fusion method, making it easier to create shapes using a 3D printer that uses the filament fusion method.

[0025] (Melt viscosity) In one embodiment, the melt viscosity is measured at a cylinder temperature 15° C. higher than the melting point Tm2 and a shear rate of 1000 sec －１ The melt viscosity of the filaments measured under these conditions is preferably 15 to 50 Pa·s, more preferably 17.5 to 50 Pa·s, even more preferably 20 to 50 Pa·s, and particularly preferably 20 to 48 Pa·s. By setting the melt viscosity of the filaments within the above range, the properties of the print lines during modeling can be set within a suitable range, and a three-dimensional model with improved molecular orientation of the liquid crystalline resin can be easily produced. The melt viscosity can be adjusted, for example, by adjusting the final polymerization temperature during melt polymerization of the liquid crystalline resin.

[0026] <Modeling Speed> The method for manufacturing a three-dimensional object according to this embodiment includes controlling the modeling speed, which is the relative movement speed between the nozzle unit and the stage of a three-dimensional modeling apparatus, to a speed faster than 35 mm / sec and slower than 1000 mm / sec (i.e., a speed greater than 35 mm / sec and less than 1000 mm / sec). The modeling speed can be controlled, for example, by inputting a value within the above-mentioned predetermined range as the relative movement speed between the nozzle unit and the stage into software provided with the three-dimensional modeling apparatus, or by inputting the movement speed of the nozzle unit and the movement speed of the stage so that the relative movement speed between the nozzle unit and the stage falls within the above-mentioned predetermined range. In this specification, the term "nozzle unit" refers to a part of a three-dimensional modeling apparatus using a filament melting process, which has a nozzle through which a filament is ejected and is controlled to move freely in three-dimensional space. The term "stage" refers to a base on which a three-dimensional object is formed by stacking filaments in a three-dimensional modeling apparatus using a filament melting process. "Relative movement speed between the nozzle unit and the stage" refers to the relative speed between any one point on the "nozzle unit" and the "stage" during modeling. Among 3D modeling devices using the filament melting method, there are those in which the stage on which the modeled object is formed is stationary and only the nozzle unit that discharges the filament moves during modeling, and those in which not only the nozzle unit that discharges the filament but also the stage on which the modeled object is formed moves during modeling. In either case, the relative movement speed between the nozzle unit and the stage is defined as the modeling speed. More specifically, the relative movement speed V between the nozzle unit and the stage in a 3D modeling device using the filament melting method is defined as follows: V = [(dX ２ +dY ２ +dZ ２ ) １／２] / dt (where dX, dY, and dZ are the movement distances of the stage at any one point on the nozzle unit in the X-axis, Y-axis, and Z-axis directions, respectively, at time dt.) By controlling the above-mentioned modeling speed at a high speed, such as faster than 35 mm / sec and slower than 1000 mm / sec, high shear orientation can be achieved, further improving the molecular orientation of the liquid crystalline resin and producing a three-dimensional model. This allows for the production of a three-dimensional model with high rigidity and little variation in mechanical properties. Furthermore, the high modeling speed further shortens the modeling time and increases productivity.

[0027] In one embodiment, a method for manufacturing a three-dimensional object by a filament melting process using a filament containing a thermoplastic resin preferably includes controlling a modeling speed, which is the relative movement speed between a nozzle unit and a stage of a three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 800 mm / sec, more preferably includes controlling it to a speed of 40 mm / sec or more and 700 mm / sec or less, even more preferably includes controlling it to a speed of 45 mm / sec or more and 600 mm / sec or less, and particularly preferably includes controlling it to a speed of 50 mm / sec or more and 500 mm / sec or less. From the viewpoint of obtaining a three-dimensional object that has high rigidity and little variation in mechanical properties, as well as a smooth surface and a superior appearance, the method for manufacturing a three-dimensional object preferably includes controlling the modeling speed to a speed faster than 35 mm / sec and slower than 500 mm / sec, more preferably includes controlling the modeling speed to a speed of 40 mm / sec or more and 450 mm / sec or less, even more preferably includes controlling the modeling speed to a speed of 45 mm / sec or more and 300 mm / sec or less, and particularly preferably includes controlling the modeling speed to a speed of 50 mm / sec or more and 200 mm / sec or less.

[0028] <Other Conditions> In one embodiment, the nozzle temperature may be set to, for example, a temperature 5 to 25° C. higher than the melting point Tm2 of the filament. In one embodiment, the discharge speed of the molten filament from the nozzle is not limited, and may be, for example, 0.5 to 10 mm ３The method for manufacturing a three-dimensional object according to this embodiment may include a step of cooling and drying the three-dimensional object after fabrication, or a step of heat-treating the three-dimensional object at a high temperature at which the three-dimensional object does not substantially deform (for example, a temperature of up to the melting point −10° C.).

[0029] <Three-dimensionally shaped object> The three-dimensionally shaped object obtained by the manufacturing method according to the embodiment of the present disclosure has a very high molecular orientation of the liquid crystalline resin, which makes it easier to exhibit the properties of the liquid crystalline resin, such as mechanical strength and heat resistance. Compared to shaped objects manufactured by other molding methods, such as extrusion, blow molding, or vacuum / pressure molding, using a thermoplastic resin containing the same liquid crystalline resin, the object has higher rigidity and less variation in mechanical properties. In a preferred embodiment, the object can also have a smooth surface and a superior appearance. Furthermore, the manufacturing method according to the embodiment of the present disclosure allows the molecules of the liquid crystalline resin to be oriented in a desired direction, thereby enabling the properties of the liquid crystalline resin, such as mechanical strength and heat resistance, to be strongly exhibited in the desired direction.

[0030] [Method for manufacturing a three-dimensional object by a filament melting method] One embodiment of the present disclosure relates to a filament used in a method for manufacturing a three-dimensional object. The filament according to this embodiment is a filament containing a thermoplastic resin, wherein the thermoplastic resin contains 55 to 100 mass % of a liquid crystalline resin based on the total mass of the thermoplastic resin, the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is 25 to 60°C, and the method includes controlling a modeling speed, which is the relative movement speed between a nozzle unit and a stage of a three-dimensional modeling apparatus, to a speed faster than 35 mm / sec and slower than 1000 mm / sec. The filament according to this embodiment has properties suitable for a method of manufacturing a three-dimensional object, including controlling the modeling speed, which is the relative movement speed between the nozzle part and the stage of the three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec. Therefore, the filament can be suitably used in the method of manufacturing a three-dimensional object by the above-mentioned filament melting method, and can produce three-dimensional objects with higher rigidity and less variation in mechanical properties.

[0031] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below: [1] A method for producing a three-dimensional (3D) object by a filament melting process using a filament containing a thermoplastic resin, wherein the thermoplastic resin contains a liquid crystalline resin in an amount of 55 to 100% by mass (preferably 60 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass) of the total thermoplastic resin (100% by mass), the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is 25 to 60°C (preferably 30 to 60°C, more preferably 30 to 55°C, even more preferably 30 to 50°C, and particularly preferably 30 to 45°C), and the production method includes controlling a modeling speed, which is the relative movement speed between a nozzle unit and a stage of a three-dimensional modeling apparatus, to a speed faster than 35 mm / sec and slower than 1000 mm / sec. [2] The manufacturing method according to [1], which includes controlling the molding speed to a speed faster than 35 mm / sec and slower than 500 mm / sec (preferably a speed of 40 mm / sec or more and 700 mm / sec or less, more preferably a speed of 45 mm / sec or more and 600 mm / sec or less, and even more preferably a speed of 50 mm / sec or more and 500 mm / sec or less). [3] The manufacturing method according to [1] or [2], wherein the diameter of the filament is 0.5 to 3.0 mm (preferably 0.5 to 2.5 mm, more preferably 1.0 to 2.5 mm, and even more preferably 1.0 to 2.0 mm). [4] The manufacturing method according to [1], wherein the cylinder temperature is 15°C higher than the melting point Tm2 and the shear rate is 1000 sec. －１[5] The method according to any one of [1] to [4], wherein the liquid crystalline resin is an aromatic polyester or aromatic polyester amide having, as a constituent component, a constituent unit derived from at least one selected from the group consisting of aromatic hydroxycarboxylic acids and derivatives thereof. [6] A filament containing a thermoplastic resin, wherein the thermoplastic resin contains 55 to 100 mass % of a liquid crystalline resin in the entire thermoplastic resin, and the difference (Tm2 - Tc) between the melting point Tm2 and the crystallization temperature Tc of the filament measured with a differential scanning calorimeter is 25 to 60°C, and the filament is used in a method for manufacturing a three-dimensional object, the method including controlling a modeling speed, which is the relative movement speed between a nozzle part and a stage of a three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec.

[0032] 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.

[0033] (Preparation of Liquid Crystalline Resin (LCP1)) The following raw material monomers, fatty acid metal salt catalyst, and acylating agent were charged into a polymerization vessel equipped with a stirrer, reflux column, monomer inlet, nitrogen inlet, and vacuum / outlet line, and nitrogen substitution was initiated. Raw material monomers: (I) 4-hydroxybenzoic acid: 1,660 g (73 mol%) (HBA) (II) 6-hydroxy-2-naphthoic acid: 837 g (27 mol%) (HNA) Fatty acid metal salt catalyst: potassium acetate catalyst: 165 mg Acylating agent: acetic anhydride: 1,714 g After charging the raw materials into the polymerization vessel, the temperature of the reaction system was raised to 140°C and the reaction was carried out at 140°C for 1 hour. Thereafter, the temperature was further raised to 325°C over 3.5 hours, and the pressure was reduced to 5 Torr (i.e., 667 Pa) over 20 minutes, and melt polymerization was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to normal pressure and then to pressurized pressure, and the polymer was discharged from the bottom of the polymerization vessel and the strands were pelletized.

[0034] (Preparation of Liquid Crystalline Resin (LCP2)) The following raw material monomers, fatty acid metal salt catalyst, and acylating agent were charged into a polymerization vessel equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a pressure reduction / outlet line, and nitrogen substitution was initiated. Raw material monomers (I) 4-hydroxybenzoic acid: 1,380 g (60 mol %) (HBA) (II) 6-hydroxy-2-naphthoic acid: 157 g (5 mol %) (HNA) (III) terephthalic acid: 484 g (17.5 mol %) (TA) (IV) 4,4'-dihydroxybiphenyl: 388 g (12.5 mol %) (BP) (V) N-acetyl-p-aminophenol: 126 g (5 mol %) (APAP) Fatty acid metal salt catalyst Potassium acetate catalyst: 110 mg Acylating agent Acetic anhydride: 1,659 g After charging the raw materials into a polymerization vessel, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 1 hour. Thereafter, the temperature was further raised to 340°C over 4.5 hours, and then the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes, and melt polymerization was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to normal pressure and then to pressurized pressure, and the polymer was discharged from the bottom of the polymerization vessel and the strands were pelletized.

[0035] [Fabrication of Filaments] [Examples 1 to 5, Comparative Examples 1 and 2] Using the liquid crystalline resin pellets obtained above, filaments having a diameter of 1.75 mm were fabricated by the following method. The liquid crystalline resin pellets were fed into a single-screw extruder (manufactured by Collin, product name: Teach-Line (registered trademark) E20 T), and extrusion was carried out under the following conditions. The extruded strand was cooled and solidified in a water bath, and then wound up with a filament winder at a winding speed such that the filament diameter became 1.75 mm ± 0.1 mm, thereby obtaining filaments. Barrel temperature: Examples 1 to 3, Comparative Example 1: 290°C; Examples 4, 5, Comparative Example 2: 340°C; Screw speed: 60 rpm

[0036] (Other thermoplastic resins (non-liquid crystal resins)) Polyetherimide (PEI): manufactured by Sabic (Saudi Arabian Basic Industries Corporation), trade name: Ultem 1000 Polycarbonate (PC): manufactured by Covestro AG, trade name: ET3113

[0037] [Fabrication of Filaments] [Examples 6 and 7, Comparative Example 3] Filaments having a diameter of 1.75 mm were fabricated using the liquid crystalline resin pellets obtained above and other thermoplastic resins (non-liquid crystalline resins) by the following method. The liquid crystalline resin pellets and other thermoplastic resins (non-liquid crystalline resins) were charged into a single-screw extruder (manufactured by Collin, product name: Teach-Line (registered trademark) E20 T) in the proportions shown in Tables 1 and 2, and extrusion was carried out under the following conditions. The extruded strand was cooled and solidified in a water bath, and then wound on a filament winder at a winding speed such that the filament diameter became 1.75 mm ± 0.1 mm, thereby obtaining filaments. Barrel temperature: Example 6: 330°C Example 7, Comparative Example 3: 300°C Screw speed: 60 rpm

[0038] (Filler) Milled glass fiber (MF): manufactured by Nippon Electric Glass Co., Ltd., trade name: EPH-80M, fiber diameter 10.5 μm, average fiber length 80 μm

[0039] [Preparation of Resin Composition] The liquid crystalline resin pellets (LCP2) obtained above and a filler (milled glass fiber (MF)) were melt-kneaded in the proportions shown in Tables 1 and 2 using a twin-screw extruder (TEX30α type, manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 350°C to obtain resin composition pellets.

[0040] [Fabrication of Filaments] [Examples 8 and 9, Comparative Example 4] Using the resin composition pellets obtained above, filaments with a diameter of 1.75 mm were fabricated by the following method. The resin composition pellets were fed into a single-screw extruder (manufactured by Zhangjiagang Friend Machinery Co., Ltd., product name: SJ45), and extrusion was carried out under the following conditions. The extruded strand was cooled and solidified in a water bath, and then wound on a filament winder at a winding speed such that the filament diameter became 1.75 mm±0.1 mm, thereby obtaining filaments. Barrel temperature: Examples 8 and 9, Comparative Example 4: 340°C Screw speed: 20 rpm

[0041] (Other filaments) Polylactic acid (PLA) filament: manufactured by Dutch Filaments, trade name: PLA175-WH-101, diameter: 1.75 mm

[0042] The melting point Tm2, ​​crystallization temperature Tc, and melt viscosity of the obtained filaments were measured using the following method. (Melting point Tm2, ​​crystallization temperature Tc) Using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X), the peak top temperature (melting point Tm1) of the endothermic peak observed when heated from room temperature at a heating rate of 20 ° C. / min (1st RUN) was measured, and then the temperature was held at (melting point Tm1 + 40) ° C. for 2 minutes, and then cooled to room temperature at a heating rate of 20 ° C. / min. The peak top temperature of the exothermic peak observed when cooled to room temperature at a heating rate of 20 ° C. / min was measured as the crystallization temperature Tc. Then, the peak top temperature of the endothermic peak observed when heated again from room temperature at a heating rate of 20 ° C. / min (2nd RUN) was measured as the melting point Tm2.

[0043] (Melt Viscosity) Using a capillary rheometer (manufactured by Toyo Seiki Seisakusho, Ltd., product name: Capillograph 1B type), the melt viscosity was measured at a cylinder temperature 15°C higher than the melting point Tm2 of the filament, using an orifice with an inner diameter of 1 mm and a length of 20 mm, at a shear rate of 1000 sec. －１ The melt viscosity of the filaments was measured under the conditions in accordance with ISO 11443. The melting point Tm2, ​​crystallization temperature Tc and melt viscosity of the obtained filaments are shown in Tables 1 and 2.

[0044] [Examples 1 to 9, Comparative Examples 1 to 4, Reference Examples 1 to 3] Three-dimensional objects were produced using each of the obtained filaments by the following method. The prepared filaments were set in a filament melting 3D printer (manufactured by NematX, product name: NEX01), and modeling was performed under the modeling conditions shown in Tables 1 and 2. As three-dimensional models, one dumbbell-shaped tensile test piece (1BA type) with a total length of 119 mm, a parallel portion width of 5 mm, and a thickness of 2 mm was obtained. The thickness direction of the test piece was parallel to the plane (x-y plane) of the 3D printer stage, and the test piece was modeled so that its longitudinal direction was the modeling direction.

[0045] (Tensile Modulus) The tensile modulus of each obtained dumbbell-shaped tensile test specimen was measured under the following conditions in accordance with ISO 527. Using a universal testing machine (manufactured by Zwick, product name: Z020), measurements were carried out on three dumbbell-shaped tensile test specimens under the following conditions, and the average tensile modulus was calculated. In addition, the difference between the maximum and minimum tensile modulus values ​​of each of the three dumbbell-shaped tensile test specimens was calculated as the range (variation). Temperature: 23°C Test speed: 2 mm / min Chuck distance (span): 65 mm The results are shown in Tables 1 and 2.

[0046] (Evaluation of Appearance) The appearance of the obtained dumbbell-shaped tensile test specimen was observed at 10x magnification using a three-dimensional image dimension measuring instrument ("LM-X" manufactured by Keyence Corporation). The appearance (surface roughness) was evaluated based on the following criteria: 1: The boundaries between the printed lines are unclear, and the surface of the test specimen is smooth. 2: The boundaries between the printed lines are clearly visible, and / or many irregularities are formed on the surface of the test specimen.

[0047] (Relationship between molding speed and tensile modulus) Furthermore, using the same type of filament as in Example 1, dumbbell-shaped tensile test specimens of the same shape and dimensions as the test specimens for tensile modulus were prepared in the same manner as the test specimens for tensile modulus, except that the molding speed was changed to 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec, and the tensile modulus was measured in the same manner as above. The relationship between molding speed and tensile modulus is shown in Figure 1.

[0048] (Relationship between molding speed and appearance of three-dimensionally molded object) Using the same type of filament as used in Example 1, dumbbell-shaped tensile test specimens of the same shape and dimensions as the test specimens for tensile modulus were prepared in the same manner as the test specimens for tensile modulus, except that the molding speed was changed to 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec. The appearance of each dumbbell-shaped tensile test specimen was observed at 10x magnification using a three-dimensional image dimension measuring device (manufactured by Keyence Corporation, "LM-X"). Photographs of each test specimen are shown in Figure 2. In Figure 2, from left to right, the photographs are of test specimens when the molding speeds were 10 mm / sec, 50 mm / sec, 100 mm / sec, and 500 mm / sec.

[0049]

[0050]

[0051] As shown in Tables 1 and 2, the three-dimensional objects obtained by the methods of Examples 1 to 9, which satisfied the requirements of this embodiment, surprisingly had a very high average value of tensile modulus and a very narrow range of tensile modulus. The three-dimensional objects obtained by the methods of Examples 1, 2, and 4 to 8 all received an appearance rating of "1," indicating superior surface appearance. On the other hand, the three-dimensional objects obtained by the methods of Comparative Examples 1 to 4, which did not satisfy the requirements of this embodiment, had a smaller average value of tensile modulus and a wider range of tensile modulus compared to the three-dimensional objects obtained by the methods of the Examples. Furthermore, as shown in FIG. 1 , when the modeling speed was faster than 35 mm / sec and slower than 1000 mm / sec, which is the configuration of this embodiment, the range of tensile modulus was narrower. As shown in Figure 2, by controlling the modeling speed to a speed faster than 35 mm / sec and slower than 500 mm / sec, the boundaries between the print lines became blurred and the surface was less uneven, resulting in a three-dimensional object with a superior appearance. In the case of Reference Examples 1 to 3, the tensile modulus did not increase even when the modeling speed was increased, and modeling was not possible when the modeling speed exceeded a certain threshold. These results confirmed that the methods of Examples 1 to 7, which satisfy the configuration of this embodiment, can produce three-dimensional objects with higher rigidity and less variation in mechanical properties. Furthermore, the methods of Examples 1 to 9, which satisfy the configuration of this embodiment, required a very short modeling time due to their high modeling speed. It was found that a high modeling speed enables the production of three-dimensional objects with higher productivity.

[0052] The method for producing a three-dimensional object by the filament melting process of this embodiment can produce a three-dimensional object by further improving the molecular orientation of the liquid crystalline resin, thereby obtaining a three-dimensional object with higher rigidity and less variation in mechanical properties, and therefore can be suitably used for producing three-dimensional objects and has industrial applicability.The filament of this embodiment can produce a three-dimensional object by further improving the molecular orientation of the liquid crystalline resin, thereby obtaining a three-dimensional object with higher rigidity and less variation in mechanical properties, and therefore can be suitably used for producing three-dimensional objects by the filament melting process and has industrial applicability.

Claims

1. A method for manufacturing a three-dimensional object by a filament melting process using a filament containing a thermoplastic resin, wherein the thermoplastic resin contains 55 to 100% by mass of a liquid crystalline resin in the entire thermoplastic resin, the difference between the melting point Tm2 and the crystallization temperature Tc of the filament (Tm2 - Tc) measured with a differential scanning calorimeter is 25 to 60°C, and the manufacturing method includes controlling the modeling speed, which is the relative movement speed between the nozzle part and the stage of a three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec.

2. The manufacturing method according to claim 1, further comprising controlling the modeling speed to a speed greater than 35 mm / sec and less than 500 mm / sec.

3. The manufacturing method according to claim 1 or 2, wherein the diameter of the filament is 0.5 to 3.0 mm.

4. A cylinder temperature 15°C higher than the melting point Tm2 and a shear rate of 1000 sec －１ The method according to claim 1 or 2, wherein the melt viscosity of the filament measured by a method using a tungsten fluoride (Tf) melting method is 15 to 50 Pa·s.

5. The manufacturing method according to claim 1 or 2, wherein the liquid crystalline resin is an aromatic polyester or aromatic polyester amide having, as a constituent component, a constituent unit derived from at least one selected from the group consisting of aromatic hydroxycarboxylic acids and derivatives thereof.

6. A filament containing a thermoplastic resin, wherein the thermoplastic resin contains 55 to 100% by mass of a liquid crystalline resin in the entire thermoplastic resin, the difference between the melting point Tm2 and the crystallization temperature Tc of the filament (Tm2 - Tc) measured with a differential scanning calorimeter is 25 to 60°C, and the filament is used in a method for manufacturing a three-dimensional object, the method including controlling the modeling speed, which is the relative movement speed between the nozzle part and the stage of a three-dimensional modeling device, to a speed faster than 35 mm / sec and slower than 1000 mm / sec.

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