Method for manufacturing filaments and shaped objects

Abstract

To provide a filament having an excellent flexibility, and also high tensile strength and flexural rigidity, and a method for manufacturing a modeled object capable of manufacturing the modeled object that excels in strength characteristics by using the filament.SOLUTION: A filament 11 is used as a modeling material of a 3D printer, and formed by impregnating a fiber bundle 25 containing a continuous reinforcing fiber 23 with a matrix resin 27. The fiber bundle 25 has a first fiber bundle group 31 and a second fiber bundle group 33. A twist angle of the first fiber bundle group 31 is smaller than a twist angle of the second fiber bundle group 33.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a filament and a shaped object. [Background technology]

[0002] In order to improve the mechanical strength of objects, the use of fused deposition modeling (FDM) 3D printers to print fiber-reinforced plastics (FRP) using continuous fiber-reinforced resin strands is expanding, and this method is being adopted in the manufacturing process of jigs, parts, and, as an example, bicycle frames.

[0003] Patent Document 1 discloses a filament (strand) used in a fused deposition model 3D printer, which comprises a base material whose main component is a thermoplastic resin, and one or more fibers or fiber bundles that are impregnated into the base material and extend in the axial direction, with these fibers or fiber bundles being twisted in the axial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-123026 Summary of the Invention [Problem to be solved by the invention]

[0005] 7A and 7B, a filament 5 having a fiber bundle 3 in which multiple fibers 1 are twisted so as to have an orientation angle inclined along the axial direction can provide good flexibility when forming an object by fused deposition modeling. However, in the case of this filament 5, because the entire fiber bundle 3 is twisted, there is a risk that the tensile strength and bending rigidity in the axial direction will decrease.

[0006] When creating a model using the fused deposition modeling method, the thermoplastic resin of the filament 5 is melted from a head equipped with a heating mechanism, and the fiber bundle 3 and the molten resin are ejected from a nozzle attached to the head and layered on a table or a base layer made up of previously ejected printing passes. If the fiber bundle 3 of the filament 5 is twisted as a whole, the fiber bundle 3 ejected from the nozzle will be difficult to open, resulting in insufficient fusion of the fiber 1 to the table or base, and the fiber 1 will likely be dispersed unevenly during modeling. This can result in a decrease in the strength of the manufactured model or variations in strength.

[0007] Therefore, an object of the present invention is to provide a filament that has good flexibility and also has high tensile strength and bending rigidity, and a method for manufacturing a shaped object that can produce a shaped object with excellent strength characteristics using the filament. [Means for solving the problem]

[0008] The present invention comprises the following configurations. (1) A filament used as a modeling material for 3D printers, in which a fiber bundle containing continuous reinforcing fibers is impregnated with a matrix resin, The fiber bundles include a first fiber bundle group and a second fiber bundle group, The twist angle of the first fiber bundle group is smaller than the twist angle of the second fiber bundle group. filament. (2) A manufacturing method of a model by thermally melting the filament of (1) and extruding the molten modeling material to form a model. [Effects of the Invention]

[0009] According to the present invention, a filament having good flexibility and high tensile strength and bending rigidity can be obtained. Furthermore, by using this filament to produce a shaped object, a shaped object having excellent strength properties can be obtained. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a schematic diagram of an FDM-type additive manufacturing device. [Figure 2A] FIG. 2A is a radial cross-sectional view perpendicular to the axial direction of the filament. [Figure 2B] FIG. 2B is a side view of the filament. [Figure 3A] FIG. 3A is a cross-sectional view in the radial direction of a filament according to Modification 1. FIG. [Figure 3B] FIG. 3B is a side view of a filament according to Modification 1. FIG. [Figure 4A] FIG. 4A is a cross-sectional view in the radial direction of a filament according to Modification 2. FIG. [Figure 4B] FIG. 4B is a side view of a filament according to Modification 2. FIG. [Figure 5] FIG. 5 is a cross-sectional view in the radial direction of a filament according to the third modification. [Figure 6] FIG. 6 is a schematic perspective view of a filament manufacturing apparatus. [Figure 7A] FIG. 7A is a radial cross-section of a conventional filament. [Figure 7B] FIG. 7B is a side view of a conventional filament. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of the 3D printer will be briefly described. The additive manufacturing device shown here is an example of a 3D printer, and other configurations may also be used.

[0012] <Configuration of additive manufacturing equipment> FIG. 1 is a schematic diagram of an FDM-type additive manufacturing apparatus 100. The additive manufacturing apparatus 100 includes a filament feeder 13 that feeds a fiber reinforced resin filament (hereinafter also referred to as a filament) 11, a head unit 15, a table 17, a molding driver 19, and a controller 21.

[0013] The filament feeding unit 13 includes a pair of drive rollers 13a that sandwich the filament 11, and a drive unit (not shown) such as a motor that rotates and drives at least one of the drive rollers 13a. The head unit 15 has a heating unit (not shown) that thermally melts the fed filament 11, and a nozzle 15a that ejects the molding material melted by the heating unit. Although not shown, the head unit 15 may also be provided with a cutting unit such as a cutter or laser cutting device that cuts the reinforcing fibers contained in the filament 11.

[0014] The table 17 is disposed opposite the nozzle 15a of the head unit 15, and has a modeling surface 17a on which models are stacked. The forming drive unit 19 moves the head unit 15 and the table 17 relative to each other, and forms the forming material discharged from the nozzle 15a of the head unit 15 along a desired path. For example, the forming drive unit 19 may be configured to include a two-axis drive mechanism that moves the head unit 15 within the plane of the forming surface 17a of the table 17, and an elevation mechanism that adjusts the stacking height by driving the table 17 up and down.

[0015] The control unit 21 has a function to control the feeding of the filament 11 by the filament feeding unit 13 and the relative movement of the head unit 15 by the molding drive unit 19, as well as a function to control the other units overall. A program that controls the units including the filament feeding unit 13 and the molding drive unit 19 is input to the control unit 21, and by executing the program, an object of a desired shape is layer-by-layer manufactured.

[0016] <Manufacturing method for molded objects> In the additive manufacturing apparatus 100 having this configuration, the control unit 21 feeds the filament 11 to the head unit 15, and the fed filament 11 is thermally melted in the head unit 15. Then, a manufacturing process is carried out in which the melted modeling material is discharged from the nozzle 15a of the head unit 15 while the head unit 15 and the table 17 are moved relative to each other. As a result, a modeled object having a desired shape is formed on the table 17.

[0017] <Filament composition> Next, the configuration of the filament 11 will be described. 2A is a radial cross-sectional view perpendicular to the axial direction of the filament 11. FIG. 2B is a side view of the filament 11.

[0018] 2A and 2B, the filament 11 is a linear resin material used as a modeling raw material for a 3D printer such as the above-described additive manufacturing device 100, and is formed by impregnating a fiber bundle 25 containing continuous reinforcing fibers 23 with a matrix resin (hereinafter also simply referred to as resin) 27 made of a thermoplastic resin. Note that the matrix resin 27 is not limited to a thermoplastic resin, and may be other resin materials such as a thermosetting resin.

[0019] The filament 11 includes, as the fiber bundles 25, a first fiber bundle group 31 and a second fiber bundle group 33. The first fiber bundle group 31 is arranged along the filament central axis O, and the second fiber bundle group 33 is arranged around the first fiber bundle group 31. The second fiber bundle group 33 is arranged radially outward of the first fiber bundle group 31, and is twisted around the first fiber bundle group 31. The first fiber bundle group 31 arranged along the filament central axis O is arranged parallel to the filament central axis O. The orientation direction of the reinforcing fibers 23 constituting the first fiber bundle group 31 is aligned parallel to the filament central axis O.

[0020] The first fiber bundle group 31 may be twisted around the filament central axis O. In this case, the twist angle of the first fiber bundle group 31 is set smaller than the twist angle of the second fiber bundle group 33.

[0021] Organic fibers such as polyethylene fiber, aramid fiber, and Zylon fiber, and inorganic fibers such as boron fiber, glass fiber, carbon fiber, metal fiber, and rock fiber can be used as the reinforcing fibers 23 of the fiber bundles 25 that make up the filament 11. Surface-treated fibers can be used as the reinforcing fibers to improve the adhesive strength between the resin and the fibers.

[0022] The thermoplastic resin, which is the main component of the matrix resin 27 of the filament 11, may be a polyolefin resin such as polypropylene or polyethylene, an acrylonitrile-butadiene-styrene resin, a polystyrene resin, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate or polylactic acid, a polyamide resin, an aromatic polyamide resin, a polyetherimide, a polyallyl imide, a polyarylate, a polyether ether ketone, a polyaryl ether ketone, a polybenzimidazole, a polyethersulfone, a polysulfone, a polyvinylidene fluoride resin, a liquid crystal polymer, a polycarbonate resin, a polyacetal, or a polyphenylene sulfide.

[0023] These thermoplastic resins may be used alone, or may be blends of multiple resins to improve the heat resistance, heat distortion temperature, heat aging, tensile properties, bending properties, creep properties, compression properties, fatigue properties, impact properties, and sliding properties of the thermoplastic resin. Examples of thermoplastic resins include polyether ether ketone resin (PEEK) / polytetrafluoroethylene (PTFE) and PEEK / polybenzimidazole (PBI). Furthermore, the thermoplastic resin may contain short fibers such as carbon fiber and glass fiber, talc, or the like.

[0024] The durability of the molded object may be improved by adding to the thermoplastic resin antioxidants such as phenols, thioethers, and phosphites, ultraviolet absorbers such as benzotriazoles or triazines, and metal deactivators such as hydrazides or amides.

[0025] Adding a plasticizer such as a phthalic acid-based or polyester-based plasticizer to a thermoplastic resin improves flexibility, thereby improving the molding accuracy during molding and the flexibility of the molded object.

[0026] Adding halogen-based, phosphate-based, inorganic, or intumescent flame retardants to thermoplastic resins can improve the flame retardancy of the resulting object.

[0027] Adding a core material such as a phosphate ester metal salt or sorbitol to a thermoplastic resin can control thermal expansion during molding, thereby improving molding accuracy.

[0028] Adding a nonionic, anionic, or cationic permanent antistatic agent to a thermoplastic resin can improve the antistatic properties of the molded object.

[0029] By adding a lubricant such as a hydrocarbon-based or metal soap-based lubricant to the thermoplastic resin to improve the lubricity of the continuous fiber reinforced filament, the filament can be smoothly fed out during molding.

[0030] The flexibility of filaments used in 3D printers can be improved by twisting the fiber bundles. However, the orientation angle of the reinforcing fibers in the fiber bundles is tilted relative to the axial direction, which can reduce the axial tensile strength and bending rigidity. Furthermore, if the entire fiber bundle is twisted, the fiber bundles ejected from the nozzle are difficult to open when creating an object using fused deposition modeling. This can result in insufficient fusion to the table 17 or substrate shown in Figure 1, and uneven dispersion of the reinforcing fibers during creation. Furthermore, the difficulty in opening the fiber bundles can easily create gaps between adjacent filaments when viewed in a planar view. This can result in a reduction in the strength of the created object or in variations in strength.

[0031] Therefore, in the filament 11 of this configuration, the fiber bundle 25 including the continuous reinforcing fibers 23 includes a first fiber bundle group 31 and a second fiber bundle group 33, and the twist angle of the first fiber bundle group 31 is smaller than the twist angle of the second fiber bundle group 33. As a result, the second fiber bundle group 33 provides good flexibility, while the first fiber bundle group 31 increases the tensile strength and bending rigidity.

[0032] When a shaped object is formed using this filament 11, the flexibility of the second fiber bundle group 33 is improved because the second fiber bundle group 33 is twisted at a larger twist angle than the first fiber bundle group 31. Therefore, when printing a curved portion, the filament 11 can easily follow the curvature of the portion, improving the shaping accuracy. In addition, in the first fiber bundle group 31, the fiber bundles 25 are smoothly spread when discharged from the nozzle, and the reinforcing fibers 23 are uniformly dispersed during molding, resulting in good fusion of the fibers to the table or substrate. Furthermore, because the fiber bundles 25 are easily spread, gaps are less likely to occur between adjacent filaments 11 in a planar view, making them easier to gather. Due to the synergistic effect of the first fiber bundle group 31 and the second fiber bundle group 33, a high-strength shaped object with reduced variations in strength can be easily obtained.

[0033] In particular, when the orientation direction of the reinforcing fibers 23 of the first fiber bundle group 31 is aligned parallel to the filament axial direction, the increase in tensile strength and bending rigidity due to the first fiber bundle group 31 becomes significant.

[0034] Next, a modified example of the filament 11 will be described. (Variation 1) Fig. 3A is a radial cross-sectional view of a filament 11A according to Modification 1. Fig. 3B is a side view of a filament 11A according to Modification 1.

[0035] As shown in FIGS. 3A and 3B , in the filament 11A according to Modification 1, the first fiber bundle group 31 arranged along the filament central axis O is also arranged parallel to the filament central axis O, and the second fiber bundle group 33 arranged radially outward of the first fiber bundle group 31 is twisted around the first fiber bundle group 31. The reinforcing fibers 23 constituting this first fiber bundle group 31 are aligned parallel to the filament central axis O. In addition, in the filament 11A according to Modification 1, the outer periphery of the second fiber bundle group 33 is covered with a resin 35. The resin 35 is preferably the same material as the matrix resin 27 described above. The regions of the first fiber bundle group 31 and the second fiber bundle group 33 may be impregnated with the resin 35 or the matrix resin 27 described above. In addition, in this configuration, the first fiber bundle group 31 may also be twisted around the filament central axis O. In this case, the twist angle of the first fiber bundle group 31 is set smaller than the twist angle of the second fiber bundle group 33.

[0036] According to this filament 11A, the outer periphery of the second fiber bundle group 33 is covered with the resin 35, and therefore, while maintaining good flexibility, the tensile strength and bending rigidity are increased by the first fiber bundle group 31. In addition, the reinforcing fibers 23 of the second fiber bundle group 33 provided on the outside of the first fiber bundle group 31 can be protected by the resin 35.

[0037] (Variation 2) Fig. 4A is a radial cross-sectional view of a filament 11B according to Modification 2. Fig. 4B is a side view of a filament 11B according to Modification 2.

[0038] 4A and 4B, in the case of the filament 11B according to Modification 2, the outer periphery of the second fiber bundle group 33 is covered with a resin 35, as in the case of the filament 11A according to Modification 1. Furthermore, grooves 37 are formed on the outer circumferential surface of the filament 11B. A plurality of grooves 37 are formed at equal intervals in the circumferential direction of the filament 11B, and are formed in a spiral shape along the filament axial direction. Note that the grooves 37 may be replaced with ridges formed on the outer circumferential surface of the filament 11B and protruding radially outward.

[0039] According to the filament 11B of this modification 2, the grooves 37 or ridges increase the surface area of ​​the outer peripheral surface, thereby improving flexibility. Note that the grooves 37 or ridges described above are not limited to a spiral shape, and may be linear along the axial direction of the filament 11B. Also, a configuration may be adopted in which a plurality of annular grooves or annular ridges are formed in the circumferential direction of the filament 11B and provided in the axial direction of the filament 11B. In other words, the outer peripheral surface of the filament 11B has irregularities formed along the filament axial direction that are either spiral, linear, or annular.

[0040] (Variation 3) FIG. 5 is a cross-sectional view in the radial direction of a filament 11C according to the third modification. 5, in a filament 11C according to Modification 3, the arrangement of the first fiber bundle group 31 and the second fiber bundle group 33 is reversed in cross section from that in the filament 11. That is, the second fiber bundle group 33 is arranged along the filament central axis O, and the first fiber bundle group 31 is arranged around the second fiber bundle group 33.

[0041] The second fiber bundle group 33 arranged along the filament central axis O is twisted with respect to the filament central axis O, and the first fiber bundle group 31 arranged around the second fiber bundle group 33 is arranged parallel to the filament central axis O. The orientation direction of the reinforcing fibers 23 constituting this first fiber bundle group 31 is aligned parallel to the filament central axis O.

[0042] According to this filament 11C, a twist is imparted to the second fiber bundle group 33 arranged radially inward of the first fiber bundle group 31. This configuration also provides good flexibility, and the first fiber bundle group 31 increases the tensile strength and bending rigidity.

[0043] In addition, in the third modification, the first fiber bundle group 31 may be twisted around the filament central axis O. In this case, the twist angle of the first fiber bundle group 31 is set smaller than the twist angle of the second fiber bundle group 33.

[0044] <Filament manufacturing method> Next, the method for producing the filament will be described. The filament production device shown here is an example, and the present invention is not limited to this. FIG. 6 is a schematic diagram of the filament manufacturing apparatus 200. The filament manufacturing apparatus 200 includes a plurality of fiber material supply sections 51 that feed out coiled fiber bundles 25 at a predetermined speed, a kneading extruder 65 that kneads and melts resin, and a resin bath section 67 that impregnates the fiber bundles 25 fed out from the fiber material supply sections 51 with resin plasticized by the kneading extruder 65.

[0045] This filament manufacturing apparatus 200 includes a cooling section 71 disposed downstream of a resin bath section 67, and a twisting section 81 disposed downstream of the cooling section 71. A composite (impregnated fiber material) 41 in which a fiber bundle 25 is impregnated with resin is fed out from the resin bath section 67. The cooling section 71 cools the composite 41 fed out from the resin bath section 67. The twisting section 81 mainly imparts a twist around the axial center to the fiber bundle 25 before cooling.

[0046] The kneading extruder 65 is provided with a rotatable screw shaft (not shown) having kneading blades in a hollow chamber 66, and melts and plasticizes the resin fed from the hopper 63.

[0047] The resin bath section 67 is formed in a cylindrical shape with the cylinder axis oriented vertically, and the resin 35 plasticized by the kneading extruder 65 is supplied to and stored inside the cylinder. The upper end of the resin bath section 67 is open, and the fiber bundle 25 guided by the guide rollers 53 is drawn into the resin stored in the resin bath section 67 from this upper end opening.

[0048] A plurality of impregnation rolls (not shown) that are rotatably held with their axes oriented horizontally are provided inside the resin bath section 67. The fiber bundle 25 introduced from the upper end opening of the resin bath section 67 is passed over each of the impregnation rolls in order and sent to the outlet section 68.

[0049] A die 69 is provided at an outlet 68 at the lower end of the resin bath section 67 to shape the outer periphery of the composite 41 of the resin and the fiber bundle 25 when the composite 41 is drawn out to the outside. Depending on the opening shape of this die 69, irregularities such as grooves 37 and ridges can be formed on the outer periphery of the filament.

[0050] The cooling section 71 is a long water tank arranged along the direction in which the composite 41 is drawn out from the resin bath section 67, and stores cooling water 72 in the tank. In the cooling section 71, the resin impregnated in the fiber bundles 25 in the composite 41 is cooled in the cooling water 72 and hardened.

[0051] The twisting unit 81 shown here is disposed downstream of the cooling unit 71 and includes a pair of upper and lower take-up rolls 83 and 85 whose outer circumferential surfaces are in contact with each other. Various mechanisms can be employed for this twisting unit 81. For example, although not shown, various configurations can be employed, such as a mechanism that rotates a bobbin around which the filament 11 is wound, around the axis of the filament 11.

[0052] The take-up rolls 83 and 85 have the function of drawing the fiber bundle 25 from the fiber material supply section 51 to the resin bath section 67, and further drawing the composite 41 from the resin bath section 67 to the cooling section 71 and twisting section 81. A separate winding section (not shown) is provided downstream of the twisting section 81, and the obtained filament 11 is wound onto a bobbin or the like.

[0053] Next, the procedure for producing the filament 11 using the above-described filament production apparatus 200 is as follows. (Impregnation process) The impregnation process is performed in the resin bath section 67 of the filament manufacturing apparatus 200. Specifically, resin supplied from a hopper 63 is kneaded in a kneading extruder 65, and the molten resin is stored in the resin bath section 67. The fiber bundles 25 are supplied to this resin bath section 67 from the fiber material supply section 51. In the resin bath section 67, the fiber bundles 25 are impregnated with the molten resin, and the impregnation amount is adjusted by passing the fiber bundles 25 through a die 69 disposed in an outlet section 68. This impregnation results in a state in which the matrix resin is present in the gaps within each fiber bundle 25, around each fiber bundle 25, and between each fiber bundle 25. The composite 41 of the matrix resin and fiber bundles 25 obtained in this manner is cooled in a cooling section 71.

[0054] (twisting process) In the twisting process, the fiber bundle 25 impregnated with resin in the resin bath section 67 is twisted by the twisting section 81. Specifically, the composite 41 that has passed through the cooling section 71 is passed through a nip between the take-up rolls 83 and 85 of the twisting section 81 while the take-up rolls 83 and 85 are rotating. This imparts a twist to the fiber bundle 25. In this example, a twist is imparted to the second fiber bundle group 33 on the outer circumferential side of the first fiber bundle group 31 along the filament central axis O. The number of twists and the twist angle can be adjusted by adjusting the inclination angle of the take-up rolls 83 and 85 with respect to the take-up direction. The closer to the filament central axis O, the smaller the twist angle can be.

[0055] In this way, the fiber bundles 25 are impregnated with a matrix resin containing a thermoplastic resin, and a filament 11 can be manufactured in which a first fiber bundle group 31 is provided along the filament central axis O and a twisted second fiber bundle group 33 is provided around the first fiber bundle group 31. When manufacturing the filament 11, twists may be imparted to both the first fiber bundle group 31 and the second fiber bundle group 33, and in this case, the twist angle of the first fiber bundle group 31 is set smaller than the twist angle of the second fiber bundle group 33.

[0056] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0057] As described above, the present specification discloses the following: (1) A filament used as a modeling material for 3D printers, in which a fiber bundle containing continuous reinforcing fibers is impregnated with a matrix resin, The fiber bundles include a first fiber bundle group and a second fiber bundle group, The twist angle of the first fiber bundle group is smaller than the twist angle of the second fiber bundle group. filament. According to this filament, the fiber bundle containing continuous reinforcing fibers includes a first fiber bundle group and a second fiber bundle group, and the twist angle of the first fiber bundle group is smaller than the twist angle of the second fiber bundle group, thereby enabling the first fiber bundle group to increase tensile strength and bending rigidity while maintaining good flexibility.

[0058] (2) The first fiber bundle group is arranged along the filament central axis, The filament according to (1), wherein the second fiber bundle group is arranged radially outward of the first fiber bundle group and is twisted around the first fiber bundle group. According to this filament, the second group of fiber bundles is arranged radially outward of the first group of fiber bundles arranged along the central axis of the filament, and twist is imparted around the first group of fiber bundles, thereby achieving a balanced increase in tensile strength and bending rigidity in the radial direction while maintaining good flexibility.

[0059] (3) The filament according to (2), wherein the orientation direction of the reinforcing fibers in the first fiber bundle group is aligned parallel to the filament axial direction. This filament has good flexibility, and the first group of fiber bundles can further increase the tensile strength and bending rigidity.

[0060] (4) The filament according to (1), wherein the outer periphery of the second fiber bundle group is covered with the matrix resin. In this filament, the outer periphery of the second fiber bundle group is covered with the matrix resin, so that the first fiber bundle group can further increase the tensile strength and bending rigidity while maintaining good flexibility, and furthermore, the matrix resin can protect the reinforcing fibers of the second fiber bundle group provided outside the first fiber bundle group.

[0061] (5) The filament according to (4), wherein a spiral groove or ridge is formed on the outer peripheral surface along the filament axis. According to this filament, a spiral groove or ridge is formed on the outer peripheral surface along the axial direction of the filament, which increases the surface area of ​​the outer peripheral surface and improves flexibility.

[0062] (6) The filament according to any one of (1) to (5), wherein the matrix resin is a thermoplastic resin or a thermosetting resin. According to this filament, the filament has a matrix resin made of a thermoplastic resin or a thermosetting resin, and while it has good flexibility, the first fiber bundle group can increase the tensile strength and bending rigidity.

[0063] (7) A method for manufacturing a shaped object, comprising thermally melting the filament according to any one of (1) to (6) and discharging the molten shaping material to layer-by-layer manufacture the shaped object. According to this method for manufacturing a shaped object, the second fiber bundle group is twisted at a larger twist angle than the first fiber bundle group, thereby improving the flexibility of the second fiber bundle group. Therefore, when printing a curved portion, the filaments can easily follow the curvature of the portion, improving the shaping accuracy. Furthermore, the first fiber bundle group has fiber bundles that are smoothly spread and uniformly dispersed during shaping, improving fiber fusion. Furthermore, because the fiber bundles are easily spread, gaps are less likely to occur between adjacent filaments in a planar view, making them easier to gather. This allows for the production of a shaped object with excellent strength characteristics. [Explanation of symbols]

[0064] 11, 11A, 11B, 11C filaments 13 Filament feeding section 15 Head 15a nozzle 17 tables 19 Forming drive unit 21 Control section 23 Reinforced Fiber 25 Fiber bundle 27 Matrix Resin 31 First fiber bundle group 33 Second fiber bundle group 35 Resin 37 Groove 41 Complex 100 Additive manufacturing equipment (3D printer) 200 Filament manufacturing equipment

Claims

1. A filament used as a modeling material for a 3D printer, in which a fiber bundle containing continuous reinforcing fibers is impregnated with a matrix resin, The fiber bundles include a first fiber bundle group and a second fiber bundle group, The twist angle of the first fiber bundle group is smaller than the twist angle of the second fiber bundle group. A filament, The first fiber bundle group is arranged along a filament central axis, The second fiber bundle group is arranged radially outward of the first fiber bundle group, and is twisted around the first fiber bundle group.

2. The orientation direction of the reinforcing fibers of the first fiber bundle group is aligned parallel to the filament axial direction. The filament of claim 1.

3. the outer periphery of the second fiber bundle group is covered with the matrix resin; The filament of claim 1.

4. A spiral groove or a ridge is formed on the outer peripheral surface along the filament axial direction. The filament of claim 3.

5. The matrix resin is a thermoplastic resin or a thermosetting resin. The filament according to any one of claims 1 to 4.

6. A method for manufacturing a molded object, which comprises thermally melting a filament described in any one of claims 1 to 4, and ejecting the thermally melted molding material to laminate-mold the molded object.

7. A method for manufacturing a molded object, which comprises thermally melting the filament described in claim 5 and ejecting the thermally melted molding material to laminate the molded object.

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