Materials for 3D printing, 3D printed objects, and 3D printing methods

Abstract

The present invention provides a material for 3D printing that exhibits good formability through 3D printing, as well as good appearance, mechanical properties, or heat resistance of the resulting printed object, and also provides a 3D printed object and a 3D printing method using the 3D printing material. [Solution] A three-dimensional molding material comprising pellets of a composition containing 5 to 70 parts by mass of carbon fiber per 100 parts by mass of thermoplastic resin, wherein the average fiber length of the carbon fibers contained in the pellets is 0.13 to 0.28 mm. A three-dimensional molded object produced using this three-dimensional molding material as a molding raw material. A three-dimensional molding method using a pellet extrusion method, which uses this three-dimensional molding material as a molding raw material.

Description

Technical Field

[0001] The present invention relates to a material for three-dimensional modeling, a three-dimensional object formed using the material for three-dimensional modeling, and a three-dimensional modeling method.

Background Art

[0002] Today, three-dimensional printers using various additive manufacturing methods (for example, binder jetting, material extrusion, powder bed fusion, and vat photopolymerization, etc.) are being sold.

[0003] Among them, in the material extrusion method (hereinafter, sometimes referred to as "ME (Material extrusion) method"), first, the modeling material is inserted into an extrusion head as a filament, pellet, powder, granule, etc. made of a thermoplastic resin, and is continuously extruded from a nozzle part provided in the extrusion head onto an X-Y plane substrate in a chamber while being heated and melted. The extruded resin is deposited on the resin laminate that has already been deposited and fused together, and solidifies integrally as it cools. Since the ME method is such a simple system, it has come to be widely used.

[0004] Conventionally, as raw materials used for the modeling material of the ME method, thermoplastic resins such as polylactic acid (hereinafter, sometimes referred to as "PLA resin") and acrylonitrile-butadiene-styrene resin (hereinafter sometimes referred to as "ABS resin") have been preferably used from the viewpoints of processability and fluidity (Patent Documents 1 to 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] While conventional PLA and ABS resins used in ME (Mechanical Engineering) fabrication materials possess sufficient mechanical properties for prototyping and model making, industrial applications requiring components and jigs demand 3D fabrication materials and 3D fabricated objects with superior mechanical properties and heat resistance.

[0007] Polycarbonate resin is known as a material with higher mechanical properties and heat resistance than PLA resin and ABS resin. However, when polycarbonate resin is used as a material for 3D printing, volume shrinkage due to the cooling and solidification of the resin is likely to occur, and the printed object may warp significantly during printing, making it difficult to ensure dimensional stability. To suppress this volume shrinkage, it is conceivable to maintain a high ambient temperature during printing, but in this case, a good appearance cannot be obtained due to insufficient cooling of the resin, and the specifications of the 3D printer used for printing become large and complex.

[0008] The object of the present invention is to provide a material for 3D printing that exhibits good formability through 3D printing, as well as good appearance, mechanical properties, or heat resistance of the resulting 3D printed object, and a 3D printed object (hereinafter sometimes simply referred to as "printed object") and a 3D printing method using the 3D printing material. [Means for solving the problem]

[0009] It is well known that incorporating fibrous fillers such as glass fibers and carbon fibers is a means of improving the mechanical properties of general thermoplastic resin molded products manufactured by injection molding or extrusion molding. In particular, polycarbonate resins blended with carbon fibers exhibit superior performance in various properties such as dimensional stability, mechanical strength, heat resistance, and electrical properties, and are therefore widely used in industrial fields such as cameras, office automation equipment, and electrical and electronic components. As a result of diligent research, the inventors have discovered that the above problems can be solved by blending carbon fibers in a specific proportion with a thermoplastic resin in a 3D modeling material and controlling the average carbon fiber length of the pellet to a specific range, thereby completing the present invention. In other words, the gist of the present invention includes the following [1] to [5].

[0010] [1] A three-dimensional molding material comprising pellets of a composition containing 5 to 70 parts by mass of carbon fiber per 100 parts by mass of thermoplastic resin, wherein the average fiber length of the carbon fiber contained in the pellets is 0.13 to 0.28 mm. [2] The material for three-dimensional molding according to [1], wherein the thermoplastic resin comprises a polycarbonate resin. [3] The material for three-dimensional molding according to [1] or [2], wherein the carbon fiber comprises recycled carbon fiber. [4] A three-dimensional object created using one of the three-dimensional molding materials described in [1] to [3] as the molding material. [5] A three-dimensional molding method using a pellet extrusion method, which uses one of the three-dimensional molding materials described in [1] to [3] as the molding material. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a material for 3D printing that has good formability through 3D printing, as well as good appearance, mechanical properties, or heat resistance of the resulting printed object, and a 3D printed object and a 3D printing method using the 3D printing material. [Brief explanation of the drawing]

[0012] [Figure 1] These are images showing the shapes of the fabricated objects produced in the examples and comparative examples. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below. The present invention is not limited to the following description and can be modified and implemented as appropriate without departing from the spirit of the invention. In this specification, when a "~" is used to enclose numerical values ​​or physical properties, it is intended to include the values ​​before and after it.

[0014] [3D modeling materials] The three-dimensional shaping material of the present invention is a three-dimensional shaping material composed of pellets of a composition (hereinafter sometimes referred to as "the composition of the present invention") containing 5 to 70 parts by mass of carbon fiber with respect to 100 parts by mass of a thermoplastic resin, wherein the average fiber length of the carbon fiber contained in the pellets (hereinafter sometimes referred to as "pellet average carbon fiber length") is 0.13 to 0.28 mm.

[0015] In the present invention, the average fiber length of the carbon fiber used in the production of the composition of the present invention and the average fiber length of the carbon fiber contained in the pellets obtained by pelletizing this composition, that is, the pellet average carbon fiber length, do not necessarily become the same. The pellet average carbon fiber length tends to be shorter than the average fiber length of the carbon fiber used in the production of the composition due to receiving various shear forces during the melt kneading in the production of the composition of the present invention and the subsequent pelletizing process. In the present invention, it has a great feature in that it defines the average fiber length of the carbon fiber in the pellets rather than the average fiber length of the raw material carbon fiber used in the production of the composition of the present invention.

[0016] <Pellet average carbon fiber length> The three-dimensional shaping material of the present invention is characterized in that the pellet average carbon fiber length, that is, the average fiber length of the carbon fiber in the pellets of the three-dimensional shaping material of the present invention, is 0.13 to 0.28 mm. If the pellet average carbon fiber length is 0.13 mm or more, a shaped object with excellent mechanical properties can be obtained. If the pellet average carbon fiber length is 0.28 mm or less, the shaping property by three-dimensional shaping and the appearance of the obtained shaped object are excellent. From these viewpoints, the pellet average carbon fiber length in the present invention is preferably 0.15 mm or more, more preferably 0.17 mm or more. Also, it is preferably 0.27 mm or less, more preferably 0.26 mm or less. The preferable upper limit value and lower limit value of the above pellet average carbon fiber length can be arbitrarily combined. For example, the pellet average carbon fiber length is preferably 0.15 to 0.27 mm, more preferably 0.17 to 0.26 mm.

[0017] <Carbon fiber> (Average fiber length of carbon fiber) The lower limit of the average fiber length of the carbon fiber used in the composition of the present invention (hereinafter sometimes referred to as "raw material carbon fiber") is preferably 0.3 mm or more, more preferably 0.5 mm or more, still more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. When the average fiber length of the raw material carbon fiber is at least the above lower limit, it is easy to satisfy the pellet average carbon fiber length described later, and there is a tendency to easily obtain a shaped article having excellent mechanical strength. The upper limit of the average fiber length of the raw material carbon fiber used in the present invention is preferably 20 mm or less, more preferably 15 mm or less, still more preferably 10 mm or less, particularly preferably 8 mm or less, and may be 5 mm or less. When the average fiber length of the raw material carbon fiber is at most the above upper limit, it is easy to satisfy the pellet average carbon fiber length described later, and when melting and shaping the three-dimensional shaping material, it has excellent fluidity, and there is a tendency to be excellent in shaping property and the appearance of the obtained shaped article.

[0018] In the present invention, the average fiber length of the raw material carbon fiber is measured by the method described in the section of Examples shown below.

[0019] As described above, the average fiber length of the raw material carbon fiber and the pellet average carbon fiber length are not necessarily the same. Generally, if the average fiber length of the raw material carbon fiber is long, the pellet average carbon fiber length also tends to be long, and if the average fiber length of the raw material carbon fiber is short, the pellet average carbon fiber length also tends to be short. In order to obtain a desired pellet average carbon fiber length, as the raw material carbon fiber, one having an average fiber length about 10 to 100 times the target pellet average carbon fiber length is used, and in order to melt-knead with a thermoplastic resin and pelletize, in the manufacturing process, it is preferable to adjust the cylinder temperature, adjust the screw rotation speed, change the screw configuration, etc. to adjust the pellet average carbon fiber length.

[0020] (Type of carbon fiber) The raw material, PAN-based carbon fiber, is primarily composed of filament fibers made from a polyacrylonitrile resin polymerized with acrylonitrile as the main component. These fibers are made infusible and then carbonized, resulting in filament fibers that consist almost entirely of carbon.

[0021] (Form of carbon fiber) Examples of raw material carbon fibers include long fibers, chopped fibers, and milled fibers. The carbon fiber may be of one type or two or more types.

[0022] While there are no particular restrictions on the average fiber diameter of the raw carbon fibers, it is more preferable that it be 3 μm or larger, and even more preferable that it be 4 μm or larger. Furthermore, it is preferable that it be 10 μm or smaller, and even more preferable that it be 8 μm or smaller. Having the number-average fiber diameter of the carbon fibers within this range makes it easier to obtain a resin composition with improved mechanical properties, particularly strength and elastic modulus.

[0023] (Recycled carbon fiber) The raw material carbon fiber used in this invention may include recycled carbon fiber (also known as "recycled carbon fiber") as at least a portion thereof.

[0024] Suitable examples of recycled carbon fibers include carbon fibers recovered from scraps of unidirectional prepregs, carbon fibers recovered from waste CFRP (carbon fiber reinforced polymer) made by curing unidirectional prepregs, carbon fibers recovered from scraps of SMC (sheet molding compound), and carbon fibers recovered from waste CFRP made by curing SMC. For example, by heating the above-mentioned scraps or waste materials at a temperature of preferably 300 to 700°C, the matrix resin is thermally decomposed, and recycled carbon fibers are obtained.

[0025] (Convergence agent) The raw carbon fiber may contain a binder. In other words, the raw material carbon fibers may be bundles of carbon fibers bound together with a binding agent. The consolidating agent is not particularly limited and examples include acrylate-based consolidating agents, polyester acrylate-based consolidating agents, urethane-based consolidating agents, polyester-based consolidating agents, and epoxy-based consolidating agents. The consolidating agent may be used alone or as a mixture of two or more types.

[0026] The lower limit of the content of the consolidator in the carbon fibers is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the carbon fiber bundle (total of carbon fibers and consolidator). If the content of the consolidator is above the above lower limit, the adhesion between carbon fibers will improve. The upper limit for the content of the converging agent in the carbon fibers is preferably 10% by mass or less, more preferably 8.0% by mass or less, and even more preferably 5.0% by mass or less, based on 100% by mass of the carbon fiber bundle. If the content of the converging agent is below the above upper limit, it is possible to obtain a molded product that has excellent balance between mechanical properties and heat resistance (resistance to deformation at high temperatures). The preferred lower and upper limits for the content of the consolidator can be arbitrarily combined, for example, 0.1 to 10% by mass is preferred, 0.3 to 8.0% by mass is more preferred, and 0.5 to 5.0% by mass is even more preferred.

[0027] (Carbon fiber content) In the composition of the present invention, the content of carbon fibers (raw material carbon fibers) is 5 to 70 parts by mass per 100 parts by mass of thermoplastic resin. The lower limit of this carbon fiber content is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and the upper limit is preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less. By having a carbon fiber content within the above range in the composition of the present invention, excellent effects on the formability of three-dimensional fabrication and the strength of the resulting fabricated object can be obtained. The preferred lower and upper limits for the carbon fiber content can be arbitrarily combined, for example, 10 to 60 parts by mass is preferred, 15 to 55 parts by mass is more preferred, and 20 to 50 parts by mass is even more preferred.

[0028] Note that, in this case, the carbon fiber content refers to the total content including the aforementioned consolidating agent, if the carbon fiber contains the aforementioned consolidating agent.

[0029] In the present invention, only one type of raw material carbon fiber may be used, or two or more types with different average fiber lengths, origins, presence or absence of a consolidator may be mixed and used.

[0030] <Thermoplastic resin> Examples of thermoplastic resins used in the present invention include polycarbonate resin, polyester resin, polyester carbonate resin, acrylic resin, cycloolefin polymer, polyoxymethylene, polyamide resin, polyolefin resin, styrene resin, polyetherketone resin, polyphenylene sulfide resin, and copolymers containing structural units derived from one or more monomers that constitute these resins. Polycarbonate resin is preferred as the thermoplastic resin because it allows for the creation of higher-strength molded products. These thermoplastic resins may be used individually or in combination of two or more types.

[0031] (Polycarbonate resin) Examples of polycarbonate resins include aromatic polycarbonate resins, aliphatic polycarbonate resins, and aromatic-aliphatic polycarbonate resins. From the viewpoint of the mechanical properties of the resulting composition pellets and molded products, aromatic polycarbonate resins are preferred as the polycarbonate resin. Polycarbonate resin may be used alone or in combination of two or more types.

[0032] Aromatic polycarbonate resins can be obtained, for example, by reacting an aromatic divalent phenol compound with phosgene or a diester carbonate.

[0033] Examples of aromatic divalent phenol compounds include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3,5-diphenyl)butane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane. These aromatic divalent phenol compounds may be used individually or in combination of two or more. Among the aromatic divalent phenol compounds, 2,2-bis(4-hydroxyphenyl)propane is preferred because it exhibits excellent mechanical properties in the resulting molded products.

[0034] Examples of diester carbonates include substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate, and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate. These diester carbonates can be used individually or in combination of two or more. Among these, diphenyl carbonate and substituted diphenyl carbonates are preferred.

[0035] Furthermore, the above-mentioned dicarboxylate may be substituted with a dicarboxylic acid or dicarboxylic acid ester in an amount of preferably 50 mol% or less, and more preferably 30 mol% or less. Typical dicarboxylic acids or dicarboxylic acid esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When substituted with such a dicarboxylic acid or dicarboxylic acid ester, a polyester carbonate resin is obtained.

[0036] The polycarbonate resin used in this invention (or a mixture of polycarbonate resins if two or more types are included) has a melt volume rate (MVR) of 5 cm².3 Preferably 10 min or more, 8 cm 3 It is more preferable that it be 10 min or longer, and also 50 cm 3 Preferably 10 min or less, and 40 cm 3 It is more preferable that the MVR of the polycarbonate resin is 10 min or less. When the MVR of the polycarbonate resin is above the lower limit, it tends to have high flowability and superior moldability, and when it is below the upper limit, the impact resistance and heat resistance of the resulting molded object tend to be maintained at a high level. Here, MVR is measured according to JIS K7210.

[0037] The viscosity-average molecular weight (Mv) of the polycarbonate resin (or a mixture of polycarbonate resins if two or more types are included) used in this invention is preferably 5,000 to 50,000, more preferably 10,000 to 50,000, and even more preferably 14,000 to 24,000. Using a polycarbonate resin with a viscosity-average molecular weight of 5,000 or more tends to improve the mechanical strength of the resulting molded object. Furthermore, using a polycarbonate resin with a viscosity-average molecular weight of 50,000 or less tends to improve the moldability of the 3D modeling material and further improve its moldability. The viscosity-average molecular weight (Mv) of polycarbonate resin is calculated from the solution viscosity measured at 25°C using methylene chloride as the solvent.

[0038] The polycarbonate resin used in this invention is not limited to virgin resin, but may also be polycarbonate resin recycled from used products (hereinafter sometimes referred to as "recycled polycarbonate resin"), or it may contain both virgin resin and recycled resin. By using recycled polycarbonate resin, it becomes possible to provide a composition that reduces environmental impact. The recycled polycarbonate resin can be any type of recycled resin, and there are no particular restrictions. Generally, methods of resin recycling include, for example, methods that utilize used molded products, resin compositions, or resins (referred to as material recycling or post-consumer recycling, etc.), or methods that utilize used molded products, resin compositions, or resins after decomposing them into oligomer or monomer units (referred to as chemical recycling, etc.). Recycled polycarbonate resin can be derived from bottles, discs, sheets, amusement equipment such as pachinko and pachislot machines, office automation equipment, semiconductor transport containers, etc. It is preferable that the recycled polycarbonate resin is recycled aromatic polycarbonate resin.

[0039] (Thermoplastic resin content) In the composition of the present invention, the lower limit of the thermoplastic resin content is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, based on 100% by mass of the total mass of the composition. If the thermoplastic resin content is above the above lower limit, a three-dimensional molding material with excellent moldability and a molded object with excellent appearance can be obtained. The upper limit of the thermoplastic resin content is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less, based on the total mass of the composition of the present invention. If the thermoplastic resin content is below the above upper limit, the ratio of carbon fibers in the composition can be increased to obtain pellets and molded products with excellent mechanical properties. The preferred lower and upper limits for the content of the thermoplastic resin can be any combination, for example, 30 to 95% by mass is preferred, 40 to 90% by mass is more preferred, 50 to 85% by mass is even more preferred, and 60 to 80% by mass is particularly preferred. Examples of carbon fibers include PAN-based carbon fibers and pitch-based carbon fibers, with PAN-based carbon fibers being preferred from the viewpoint of mechanical properties.

[0040] As mentioned above, the composition of the present invention preferably contains a polycarbonate resin as the thermoplastic resin. When a thermoplastic resin other than polycarbonate resin is used as the thermoplastic resin, it is preferable that the polycarbonate resin content in the thermoplastic resin is 40% by mass or more, particularly 60% by mass or more, and especially 80% by mass or more and 100% by mass or less.

[0041] <Other ingredients> The composition of the present invention may contain other components not mentioned above, as long as they do not impair the effects of the present invention. Other components that may be contained in the composition of the present invention include, for example, inorganic fillers, freshness preservatives, antibacterial agents, lubricants, plasticizers, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, hydrolysis inhibitors, crystal nucleating agents, impact resistance improvers, antiblocking agents, lightfasteners, plasticizers, heat stabilizers, flame retardants, mold release agents, antifogging agents, surface wetting improvers, incineration aids, dispersion aids, surfactants, slip agents, and the like. These may be used individually or in combination of two or more.

[0042] For example, the composition of the present invention may contain an inorganic filler from the viewpoint of making layer lines less noticeable and improving the appearance of the molded product, and from the viewpoint of improving the elastic modulus of the pellet and thus improving handling properties. Examples of inorganic fillers include anhydrous silica, mica, talc, titanium dioxide, calcium carbonate, diatomaceous earth, allophane, bentonite, potassium titanate, zeolite, sepiolite, smectite, kaolin, kaolinite, glass fibers, glass flakes and other glass materials, limestone, carbon (excluding carbon fibers of the average fiber length mentioned above), wollastonite, calcined perlite, silicates such as calcium silicate and sodium silicate, hydroxides such as aluminum oxide, magnesium carbonate, and calcium hydroxide, salts such as ferric carbonate, zinc oxide, iron oxide, aluminum phosphate, and barium sulfate, with talc, calcium carbonate, and zeolite being preferred. These can be blended as desired without impairing the effects of the present invention, and one type may be used alone or two or more types may be mixed and used.

[0043] Specifically, ester-based surfactants of a saturated or unsaturated aliphatic carboxylic acid having 4 to 20 carbon atoms and a polyhydric alcohol are preferably used as anti-fogging agents.

[0044] Examples of slip agents include unsaturated or saturated fatty acid amides and unsaturated or saturated fatty acid bisamides, which consist of unsaturated or saturated fatty acids having 6 to 30 carbon atoms. Most preferably, slip agents include erucic acid amide, oleic acid amide, stearic acid amide, and their bisamides. These can be arbitrarily blended within a range that does not impair the effects of the present invention, and one type may be used alone or two or more types may be used in combination.

[0045] Examples of antiblocking agents include saturated fatty acid amides or bisamides with 6 to 30 carbon atoms, methylolamides, ethanolamides, natural silica, synthetic silica, synthetic zelite, and talc.

[0046] Specifically, the lightfastening agents include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2-(3,5-di-t-butyl-4-hydroxyphenyl)-2-n-butyl-bis(2,2,6,6-tetramethyl-4-piperidyl) malonate, and 2-(3,5-di-t-butyl 2-4-hydroxyphenyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-bis(2,2,6,6-tetramethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate, tetrakis(2 ,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, mixed(2,2,6,6-tetramethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, mixed(1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl)-1,2, 3,4-Butanetetracarboxylate, mixed {2,2,6,6-tetramethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethyl}-1,2,3,4-Butanetetracarboxylate, mixed {1,2,2,6,6-pentamethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]Undecane]diethyl}-1,2,3,4-butanetetracarboxylate, 1,2-bis(3-oxo-2,2,6,6-tetramethyl-4-piperidyl)ethane, 1-(3,5-di-t-butyl-4-hydroxyphenyl)-1,1-bis(2,2,6,6-tetramethyl-4-piperidyloxycarbonyl)pentane, poly[1-oxyethylene(2,2,6,6-tetramethyl-1,4-piperidyl)oxysuccinyl], poly[2-(1,1,4-trimethylbutylimino)-4,6-triazinedi Examples include yl-(2,2,6,6-tetra and-4-piperidyl)iminohexamethylene-(2,2,6,6-tetramethyl-4-piperidyl)imino), N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate and its N-methyl compound, and polycondensates of succinic acid and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine. Among these, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl) malonate are particularly preferred.

[0047] Examples of UV absorbers include benzophenone-based, benzotriazole-based, salicylic acid-based, and cyanoacrylate-based UV absorbers. Among these UV absorbers, benzotriazole-based UV absorbers are preferred, specifically 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxyphenol.

[0048] Antioxidants include BHT (dibutylhydroxytoluene), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,3',3”,5,5',5”-hexa-tert-butyl-α,α',α”-(mesitylene-2,4,6-triyl)tri-p-cresol, and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl). Propionate, 1,3,5-Tris[(4-tert-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, Calcium diethylbis[{3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl}methyl]phosphonate, Bis(2,2'-diethyl) Hindered phenol antioxidants such as droxy-3,3'-di-tert-butyl-5,5'-dimethylphenyl)ethane, N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl)-4-hydroxyphenyl]propionamide, tridecyl phosphite, diphenyldecyl phosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonate, bis[2,4-bis(1,1-dimethylethyl)- Examples include phosphorus-based antioxidants such as 6-methylphenyl]ethyl ester phosphorous acid and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, lactone-based antioxidants such as reactive compounds of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and xylene, sulfur-based antioxidants such as dilauryl thiodipropionate and distearyl thiodipropionate, and mixtures of two or more of these. Among these, hindered phenol-based antioxidants are preferably used.

[0049] The content of these other components may be such that, in order not to impair the physical properties of the three-dimensional molding material of the present invention, the total amount of the components to be mixed may be 0.01% by mass or more and 20% by mass or less relative to the total amount of the composition of the present invention.

[0050] <Format of materials for 3D modeling> The three-dimensional molding material of the present invention is preferably in the form of pellets and is applied to a three-dimensional printer using the pellet extrusion method. The pellet-shaped three-dimensional molding material is also preferable from the viewpoint of moldability. Here, "formability" in this specification refers to handling or extrusion in the context of molding, and a material that excels in at least one of these is considered to have good formability, while one that excels in both is considered more preferable. Furthermore, when using multiple thermoplastic resins as exemplified above, the three-dimensional molding material of the present invention may be made by mixing the multiple resins to create a homogeneous material, or by separating the two or more resins used into different layers to create a multilayer structure.

[0051] The specific shape of the pellet-shaped 3D molding material of the present invention is not particularly limited, but examples include cylindrical (including those with an elliptical cross-section), prismatic, spherical, rice grain-shaped (rugby ball-shaped), disc-shaped, and cube-shaped.

[0052] <Method for manufacturing materials for 3D modeling> The three-dimensional molding material of the present invention is manufactured by supplying, for example, a thermoplastic resin and carbon fibers, along with other components as needed, to an extruder, melting and kneading them in the extruder, and then extruding them to produce the composition of the present invention, while pelletizing them using any method such as strand cutting or hot cutting. Furthermore, the thermoplastic resins and carbon fibers used are those exemplified in the sections on <Thermoplastic Resins> and <Carbon Fibers> mentioned above.

[0053] In the production of the composition of the present invention, each component may be pre-mixed and supplied to the extruder all at once, or the components may be supplied to the extruder using a feeder, either without pre-mixing or with only a portion of them pre-mixed. The extruder may be a single-screw extruder or a twin-screw extruder. Alternatively, some components of the dye or pigment (e.g., carbon black) may be melt-kneaded with the resin component to prepare a masterbatch, and then the remaining components may be added and melt-kneaded therein. It is also preferable to supply the carbon fibers from a side feeder in the middle of the extruder cylinder. The heating temperature during melt-kneading can usually be appropriately selected from the range of 250 to 350°C.

[0054] The 3D modeling material of the present invention, after being manufactured by the above method, is preferably dried at 120°C or higher for about 4 to 6 hours to achieve a low moisture content before use. It may be stored sealed in an aluminum inner bag or a polyethylene bag. The moisture content of the modeling material after drying is preferably 0.3% or less. More preferably 0.2% or less, even more preferably 0.1% or less, and particularly preferably 0.05% or less. A moisture content below the above upper limit is preferable because it reduces foaming and smoke generation during extrusion, and stabilizes the dimensional stability and mechanical strength of the resulting modeled product. The moisture content is measured by the Karl Fischer method.

[0055] [Modeled object / 3D modeling method] In one embodiment, the present invention relates to a three-dimensional object and a three-dimensional object manufacturing method using the three-dimensional object manufacturing material. The three-dimensional object can be manufactured by using the three-dimensional object manufacturing material and manufacturing it with a pellet extrusion type three-dimensional printer. Pellet extrusion type three-dimensional printers are preferred from the viewpoint of being suitable for a wide variety of resins and having excellent handling properties for the three-dimensional object manufacturing material. Furthermore, when manufacturing the object of the present invention, the 3D printing material of the present invention or a printing material made of another resin may be used simultaneously as a support material during the manufacturing process, and after the manufacturing is complete, this support material may be removed to obtain the object of the present invention. In 3D modeling, "support material" generally refers to auxiliary structures created to support the target object during the modeling process, preventing it from losing balance and falling over, deforming under its own weight, bending, or otherwise breaking.

[0056] Pellet extrusion 3D printers generally include a heatable build table, extrusion nozzle, heat melter, and material supply unit. Some of these 3D printers have the extrusion nozzle and heat melter integrated into a single unit.

[0057] The extrusion nozzle can be moved arbitrarily on the XY plane of the build table by being installed in a gantry structure or a multi-axis robot arm. Furthermore, especially when installed in a multi-axis robot arm, it can be moved not only on the XY plane but also along any arbitrary path within the 3D space of the build area. The build table is a platform for constructing the target object and support materials, and it is preferable that it has specifications that allow for heating and maintaining the temperature to achieve adhesion with the object, and to improve the dimensional stability of the resulting object so that it becomes the desired three-dimensional object. Typically, at least one of the extrusion nozzle and build plate is movable in the Z-axis direction, which is perpendicular to the XY plane. Some printers also have configurations where the nozzle moves only in the X (or Y) direction, while the build plate moves in the Y (or X) direction.

[0058] The pellet-shaped 3D molding material of the present invention is fed from a raw material supply unit such as a quantitative feeder or hopper, melted by a screw or piston, and sent to an extrusion nozzle, where it is extruded from the nozzle tip. The material extruded from the nozzle is deposited onto the build plate by signals transmitted based on the 3D model, causing the extrusion nozzle or build plate to move. After this process is complete, the deposited material is removed from the substrate, and if necessary, support materials are removed and excess parts are trimmed to obtain the desired 3D object.

[0059] The temperature of the molten resin (molten 3D molding material) discharged from the extrusion nozzle is preferably 150°C or higher, more preferably 200°C or higher, while it is preferably 400°C or lower, and more preferably 350°C or lower. When the temperature of the molten resin is above the lower limit, the resin flows sufficiently, which tends to result in a superior molded appearance even when molded at high speed, and is therefore preferable. On the other hand, when the temperature of the molten resin is below the upper limit, it tends to suppress molding defects such as thermal decomposition of the resin, deterioration accompanied by discoloration due to overheating (burning), smoke, odor, poor mold release due to stickiness, and the generation of foreign matter (clumps) caused by lumps of resin adhering to the surface of the molded object.

[0060] The extrusion nozzle that extrudes the molding material has a diameter of 0.5 to 20 mm, particularly 1 to 10 mm, and it is preferable that the molding material is extruded in strands with a diameter of 0.5 to 20 mm, particularly 1 to 10 mm. This shape of extrusion from the nozzle is preferable because it provides excellent productivity for the molded object and allows the extruded resin to cool appropriately.

[0061] The molded objects produced in this manner may be subjected to secondary post-processing. Examples of post-processing include cutting, drilling, machining, polishing, painting, printing, film transfer, plating, and vacuum deposition.

[0062] [Uses of the sculptures] The molded products of the present invention have good mechanical strength and excellent appearance, making them suitable for a variety of applications, such as various storage containers, electrical and electronic equipment components, office automation (OA) equipment components, home appliance components, mechanical mechanism components, various parts for automobiles, motorcycles, bicycles, building materials, industrial products, large jigs and fixtures such as autoclave molds, molds, and interior products. [Examples]

[0063] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0064] [Raw materials] The abbreviations for the raw materials used in the following examples and comparative examples are shown below.

[0065] <Thermoplastic resin (A)> • A-1: ​​Polycarbonate resin (product name "XANTAR(registered trademark) 7022J", manufactured by Mitsubishi Chemical Corporation) MVR: 13cm 3 / min Mv: 22,000

[0066] <Carbon fiber (B)> • B-1: PAN-based recycled carbon bundle (product name "T8S103CD0R", manufactured by CFRI Co., Ltd.) • B-2: PAN-based recycled carbon fiber bundle (product name "fiberball 100AC", manufactured by Mitsubishi Chemical Corporation) • B-3: PAN-based carbon bundle (product name "TR06U", manufactured by Mitsubishi Chemical Corporation)

[0067] [Measurement of average fiber length of carbon fibers] The average fiber length of the raw carbon fiber (carbon fiber (B)) was calculated by spreading carbon fibers, from which the consolidating agent had been removed by thermal decomposition or solvent, on a flat surface, extracting 300 or more carbon fibers with a length of 50 μm or more, measuring their lengths, and calculating the weighted average fiber length. Alternatively, the fiber length can be calculated by binarizing images captured by microscopic observation using image processing software such as ImageJ. The average fiber length of the carbon fibers contained in the pellets (average carbon fiber length of the pellets) was also measured using the same procedure.

[0068] Table 1 shows the average fiber length of each raw material carbon fiber (B), as well as the type and content of the consolidating agent.

[0069] [Table 1]

[0070] [Extruder] For the production of pellets for 3D modeling, we used "TEX44αII" manufactured by Japan Steel Works, Ltd. The extruder feeders consisted of a main raw material (thermoplastic resin) feeder and a side feeder for carbon fiber supply, installed from upstream. The extruder had two kneading zones: one between the main raw material feeder and the side feeder, and another between the side feeder and the die. The cylinder temperature was set between 60 and 320°C. Pellet pellets were obtained by performing strand cutting at the outlet of the extruder.

[0071] [Example 1, Comparative Examples 1-2] Thermoplastic resin A-1 and carbon fibers B-1, B-2, or B-3 were mixed in the proportions shown in Table 2, and pellets (cylindrical shape) of 3D modeling material were produced using the extruder described above. The average fiber length within the pellets (average carbon fiber length of the pellets) was measured using the method described above. The results are shown in Table 2.

[0072] <Creation of Sculptural Objects> Using the pellets obtained above as the material for 3D printing, an object with the shape shown in Figure 1 was fabricated using a 3D printer with a screw-type extruder (S.Lab "GEM 550D"). The nozzle diameter was 6 mm and the layer thickness was 3 mm. The printing temperature conditions were a cylinder temperature of 260-300°C and a build table temperature of 60°C. The printing speed was 600 mm / min. Furthermore, in all of the examples and comparative examples, the fabrication quality achieved by this 3D printing method was excellent.

[0073] <Visual evaluation of the structure> The objects created as described above were visually inspected and evaluated according to the following criteria A and B. The final judgment was made by majority vote of five experts. A: There is no exposure of carbon fibers on the surface, and the surface is uniform and smooth. B: The surface is uneven and rough due to exposed carbon fibers, etc. The results are shown in Table 2.

[0074] <Preparation of test specimens> The fabricated object obtained above was cut to produce flat test specimens measuring 80 mm x 10 mm x 4 mm in thickness, with the surface of the test specimen facing the flow direction during fabrication (XY direction) and the direction perpendicular to the flow direction (Z direction).

[0075] <Bending Test> Using the test specimens obtained above, flexural strength and flexural modulus were measured in accordance with ISO 178. The unit is expressed in MPa. The results are shown in Table 2.

[0076] <Temperature of deflection under load> Using the test specimens obtained above, the temperature of deflection under load was measured in accordance with ISO 75-1 and ISO 75-2 under conditions of 23°C and a load of 1.80 MPa (Method A). The unit is shown in °C. The results are shown in Table 2.

[0077] [Table 2]

[0078] As is clear from the results above, in 3D printing materials with a short average carbon fiber length per pellet, as in Comparative Example 1, good mechanical strength could not be obtained, and heat resistance was also poor. In 3D printing materials with an excessively long average carbon fiber length per pellet, as in Comparative Example 2, the appearance of the printed object was poor. In contrast, it can be seen that by controlling the average carbon fiber length of the pellets to 0.13 to 0.28 mm, as in Example 1, it is possible to achieve both a good molded appearance and good mechanical properties and heat resistance.

[0079] As described above, the present invention provides a 3D printing material with good formability (handling during printing, etc.), appearance, mechanical properties, and heat resistance of the resulting printed object, as well as a 3D printed object and a 3D printing method using this 3D printing material.

Claims

1. A three-dimensional molding material comprising pellets of a composition containing 5 to 70 parts by mass of carbon fiber per 100 parts by mass of thermoplastic resin, wherein the average fiber length of the carbon fibers contained in the pellets is 0.13 to 0.28 mm.

2. The material for three-dimensional molding according to claim 1, wherein the thermoplastic resin includes a polycarbonate resin.

3. The material for three-dimensional molding according to claim 1, wherein the carbon fibers include recycled carbon fibers.

4. A three-dimensional object formed using the three-dimensional molding material described in any one of claims 1 to 3 as the molding material.

5. A three-dimensional molding method by pellet extrusion, using the three-dimensional molding material described in any one of claims 1 to 3 as the molding raw material.

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