Composition and filament for carbon molded body for production of carbon molded body by three-dimensional printer molding and carbonization

Abstract

To provide a composition that can be molded using a three-dimensional printer, and from which a carbon molded article can be obtained by carbonizing the obtained molded article.SOLUTION: A composition for a carbon molded body of the present invention for producing a carbon molded body by three-dimensional printer molding and carbonization, contains a pitch. A content ratio of the pitch is 10 mass% or more with respect to a mass of the composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for a carbon formed body, particularly a composition for a carbon formed body that can be formed by a 3D printer and can maintain its shape during carbonization. The present invention also relates to a filament composed of such a composition for a carbon formed body.

Background Art

[0002] A three-dimensional (3D) printer is a technology that calculates the shape of a thin cross-section from 3D data input by CAD or the like and creates a three-dimensional object by laminating materials in multiple layers based on this calculation result. It is also called Additive Manufacturing Technology. Since a 3D printer does not require a mold used in injection molding and can create complex three-dimensional structures that cannot be molded by injection molding, it has attracted attention as a multi-variety, small-batch production technology.

[0003] For materials for 3D printers (also referred to as additive manufacturing materials), various materials have been developed according to the type and application of 3D printers. As main materials, photocurable resins, thermoplastic resins, metals, ceramics, waxes, etc. are used.

[0004] The methods of 3D printers are classified into (1) binder spraying method, (2) directed energy deposition method, (3) material extrusion method, (4) material spraying method, (5) powder bed fusion bonding method, (6) sheet lamination method, (7) liquid tank photopolymerization method, etc. according to the method of three-dimensionally shaping materials. Among the above methods, 3D printers adopting the material extrusion method (also called the fused deposition modeling method) have been becoming cheaper and the demand for home and office use is increasing. In addition, 3D printers adopting the powder bed fusion bonding method are attracting attention because the development of a system that realizes improved recyclability of powder materials is progressing.

[0005] The hot melt lamination method (material extrusion method) is a method of forming by extruding a thermoplastic resin having a filamentous or other shape called a filament, fluidizing it with a heating means inside an extrusion head, discharging it from a nozzle onto a platform, and cooling and solidifying it while laminating it little by little according to the cross-sectional shape of the target object to be formed.

[0006] As resin compositions for such 3D printers using the hot melt lamination method, various compositions have been disclosed.

[0007] Patent Document 1 discloses a resin composition containing inorganic fibers having an average fiber length of 1 μm to 300 μm and an average aspect ratio of 3 to 200, and a thermoplastic resin, and a resin composition that is a modeling material for a 3D printer.

[0008] Patent Document 2 discloses a filament for a hot melt lamination type 3D printer, which is formed of a functional resin composition containing a matrix resin having thermoplasticity and a functional nanofiller dispersed in the matrix resin having thermoplasticity.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] The molded article that can be molded by a conventional 3D printer was a resin-based molded article.

[0011] In contrast, the present invention provides a composition that can be molded by a three-dimensional printer and from which a carbon molded body can be obtained by carbonizing the obtained molded body.

Means for Solving the Problems

[0012] As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows: <Aspect 1> A composition for a carbon molded body for manufacturing a carbon molded body by three-dimensional printer molding and carbonization, containing pitch, wherein the content rate of the pitch is 10% by mass or more with respect to the mass of the composition for a carbon molded body. Composition for a carbon molded body. <Aspect 2> The composition for a carbon molded body according to Aspect 1, wherein the softening point of the pitch is 50°C or higher and 400°C or lower. <Aspect 3> The composition for a carbon molded body according to Aspect 1 or 2, further containing a thermoplastic resin. <Aspect 4> The composition for a carbon molded body according to Aspect 3, wherein the residual carbon rate of the thermoplastic resin is 30% or less. <Aspect 5> The composition for a carbon molded body according to Aspect 3 or 4, wherein the content rate of the thermoplastic resin is 10% by mass or more and 80% by mass or less with respect to the mass of the composition for a carbon molded body. <Aspect 6> The composition for a carbon molded body according to any one of Aspects 1 to 5, further containing a carbonaceous filler. <Aspect 7> The composition for a carbon molded body according to Aspect 6, wherein the carbonaceous filler is at least one selected from the group consisting of graphite and carbon fiber. <Aspect 8> The composition for a carbon molded body according to Aspect 6 or 7, wherein the content rate of the carbonaceous filler is 10% by mass or more and 80% by mass or less with respect to the mass of the composition for a carbon molded body. <Aspect 9> The composition for a carbon molded body according to any one of Aspects 1 to 8, wherein the residual carbon rate of the entire composition for a carbon molded body is 15% or more and 85% or less. <Aspect 10> A filament for manufacturing a carbon formed body by three-dimensional printer forming and carbonization, which is composed of the composition for a carbon formed body according to any one of Aspects 1 to 9.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a composition that can be formed by a three-dimensional printer and from which a carbon formed body can be obtained by carbonizing the obtained formed body.

Embodiments for Carrying Out the Invention

[0014] 《Composition for Carbon Formed Body》 The composition for a carbon formed body of the present invention is a composition for a carbon formed body for manufacturing a carbon formed body by three-dimensional printer forming and carbonization, containing pitch, and the content rate of the pitch is 10% by mass or more based on the mass of the composition.

[0015] That is, the present invention also relates to the use of the above-described composition for a carbon formed body for manufacturing a carbon formed body by three-dimensional printer forming and carbonization.

[0016] The composition for a carbon formed body of the present invention can be made into the form of a filament for manufacturing a carbon formed body by three-dimensional printer forming and carbonization, that is, it can be supplied to the extrusion head of a 3D printer, and can be made into the form of a filament that can maintain its shape by carbonization.

[0017] The present inventors have found that a composition for a carbon formed body can be obtained in which the composition for a carbon formed body contains pitch at the above-described content rate, can be formed by a three-dimensional printer, and can maintain its shape after carbonization. Although not wishing to be bound by theory, this is considered to be due to the fact that pitch has both a high residual carbon rate and fluidity at high temperatures.

[0018] The residual carbon ratio of the composition for carbon molded bodies of the present invention may be 15% by mass or more and 85% by mass or less. This residual carbon ratio may be 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more, and may also be 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, or 55% by mass or less.

[0019] Here, regarding the present invention, the "residual carbon ratio" is a value measured as follows.

[0020] (Residual carbon ratio) Using a thermobalance, the temperature is raised from room temperature to 900 °C at a rate of 20 °C / min in a nitrogen atmosphere, and the temperature at 850 °C is taken as the mass after firing. The residual carbon ratio (mass %) is calculated by the following formula. Residual carbon ratio (%) = (mass after firing (850 °C) / mass before firing) × 100

[0021] The composition for carbon molded bodies of the present invention may further contain an arbitrary thermoplastic resin, particularly a thermoplastic resin having a residual carbon ratio of 30% or less. Due to the presence of such a thermoplastic resin, when molding with a 3D printer, the composition for carbon molded bodies is likely to undergo plastic deformation, thereby enabling good moldability with a 3D printer.

[0022] The composition for carbon molded bodies of the present invention may further contain an arbitrary carbonaceous filler. Due to the presence of the carbonaceous filler, the residual carbon ratio of the entire composition for carbon molded bodies can be increased, thereby making it easier to maintain the shape before carbonization even after carbonization.

[0023] The composition for carbon molded bodies of the present invention can be obtained by kneading each substance constituting it together with a solvent component and molding it by means such as known extrusion molding. As the solvent component, for example, alcohols such as ethanol can be used.

[0024] In addition, all the mass contents mentioned in this specification are based on the solid content, that is, the mass of components other than the solvent component.

[0025] Hereinafter, each component of the present invention will be described.

[0026] 〈Pitch〉 Pitch generally means a solid at normal temperature among the by-products of petroleum and coal tar. By carbonizing pitch, amorphous carbon can be produced.

[0027] As the pitch, either mesophase pitch or isotropic pitch may be used.

[0028] Mesophase pitch means a pitch in which the constituent molecules are in a liquid crystal state and are oriented. Isotropic pitch means a pitch in which the constituent molecules are randomly oriented and is optically isotropic.

[0029] As such pitch, commercially available ones can be used.

[0030] The residual carbon rate of the pitch may be 15% by mass or more and 85% by mass or less. This residual carbon rate may be 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more, and may also be 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, or 55% by mass or less.

[0031] The softening point of the pitch may be 50°C or higher and 400°C or lower. This softening point may be 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, or 240°C or higher, and may also be 400°C or lower, 390°C or lower, 380°C or lower, 370°C or lower, 360°C or lower, 350°C or lower, 340°C or lower, 330°C or lower, 320°C or lower, 310°C or lower, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, or 260°C or lower. Among these, from the viewpoint of making the physical strength of the obtained carbon molded body higher, it is preferable that this softening point is 200°C or higher. Also, a pitch having a softening point of 350°C or lower generally has a low quinoline insoluble content and toluene insoluble content, and thus is preferable from the viewpoint of performing a more stable three-dimensional shaping.

[0032] Here, the softening point is measured by the ring and ball method in accordance with JlS K2425. Specifically, first, a sample passing through an 840 μm (20 mesh) sieve is heated and dissolved at a temperature not exceeding 50°C higher than the estimated softening point, poured into a φ16×H6.4 mm ring, and solidified. Next, this ring is placed on the sample shelf, and a steel ball with a diameter of φ9.525 mm and a weight of 3.5 g is placed at the center of the ring. This shelf is immersed in glycerin, the bath temperature is raised at 5°C / min, and the temperature when the sample softens and the steel ball reaches the bottom plate 25.4 mm below the ring is taken as the softening point.

[0033] 〈Thermoplastic resin〉 As the thermoplastic resin, for example, a thermoplastic resin having a residual carbon rate of less than 30% can be used. This residual carbon rate may be 25% or lower, 20% or lower, 15% or lower, 10% or lower, 5% or lower, 3% or lower, or 1% or lower, and may also be 0%, and particularly being 10% or lower is preferable from the viewpoint of improving the moldability by a 3D printer.

[0034] Examples of such thermoplastic resins include vinyl resins such as vinyl chloride resin and vinyl acetate resin, acrylic resins such as polymethyl methacrylate (PMMA), thermoplastic polyimide (TPI), styrene resin, polyolefin resin, and copolymers thereof. As these thermoplastic resins, commercially available ones can be used.

[0035] The content of the thermoplastic resin may be 10% by mass or more and 80% by mass or less based on the mass of the carbon molding composition. From the viewpoint of obtaining a molded body after carbonization, it is preferable that this content is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more. This content may be 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, 50% by mass or less, or 45% by mass or less.

[0036] The melt mass flow rate of the thermoplastic resin conforming to JIS K7210-1 may be 0.1 g / 10 min or more and 2.5 g / 10 min or less when measured under the conditions of a temperature of 360°C and a load of 2.16 kgf. For example, it may be 0.1 g / 10 min or more, 0.5 g / 10 min or more, or 1.0 g / 10 min or more, and may also be 10.0 g / 10 min or less, 5.0 g / 10 min or less, 3.0 g / 10 min or less, or 2.5 g / 10 min or less.

[0037] The melting point of the thermoplastic resin may be 250°C or more and 400°C or less. For example, it may be 250°C or more, 260°C or more, 270°C or more, 280°C or more, 290°C or more, 300°C or more, 310°C or more, or 315°C or more, and may also be 400°C or less, 390°C or less, 380°C or less, 370°C or less, 360°C or less, 350°C or less, 340°C or less, 330°C or less, or 325°C or less.

[0038] The thermal decomposition temperature of the thermoplastic resin may be 380°C or higher and 500°C or lower, for example, it may be 380°C or higher, 390°C or higher, 400°C or higher, 410°C or higher, 420°C or higher, or 430°C or higher, and may also be 500°C or lower, 490°C or lower, 480°C or lower, 470°C or lower, 460°C or lower, 450°C or lower, or 440°C or lower.

[0039] Here, in the present invention, the melting point and the thermal decomposition temperature can be measured by differential thermal-thermogravimetric simultaneous analysis (TG-DTA) under a nitrogen atmosphere and at a heating rate of 10°C / min. Specifically, under a nitrogen atmosphere, the sample is heated at a heating rate of 10°C / min, and by differential thermal-thermogravimetric simultaneous analysis (TG-DTA) conforming to JIS K0129, a curve with the vertical axis being mass and the horizontal axis being temperature (TG curve), and a curve with the vertical axis being temperature difference and the horizontal axis being temperature (DTA curve) are obtained, thereby obtaining the melting point and the thermal decomposition temperature. More specifically, when an endothermic peak is observed in the curve of the DTA curve at a position where no decrease in mass is observed in the TG curve, the temperature at which this minimum value is taken can be defined as the melting point. Also, when a decrease in mass is observed in the TG curve, the temperature at which the decrease in mass starts can be defined as the thermal decomposition temperature.

[0040] 〈Carbonaceous filler〉 The carbonaceous filler may be carbon fibers and / or carbon particles dispersed in the pitch. This carbonaceous filler will be dispersed in the amorphous carbon in the carbon molded body obtained after carbonization.

[0041] Examples of the carbon fibers include, but are not limited to, mild fibers and chopped fibers. These may be used alone or in combination.

[0042] The average length of the carbon fibers may be 10 μm or more and 800 μm or less, for example, it can be 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, 65 μm or more, 70 μm or more, 75 μm or more, 80 μm or more, 85 μm or more, or 90 μm or more, and it can also be 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, 180 μm or less, 150 μm or less, 120 μm or less, or 110 μm or less.

[0043] The average fiber diameter of the carbon fibers may be 1 μm or more and 20 μm or less, for example, it can be 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and it can also be 20 μm or less, 15 μm or less, 12 μm or less, or 10 μm or less. The average length of the carbon fibers can be determined by randomly selecting and observing and measuring 50 or more fibers using a scanning electron microscope (SEM) or the like and calculating the number average.

[0044] Examples of the carbon particles include graphene, carbon nanotubes, graphite, and carbon black. These may be used alone or in combination.

[0045] The shape of the carbon particles is not particularly limited and may be, for example, a flat shape, an array shape, a spherical shape, or the like.

[0046] The average particle diameter of the carbon particles may be 100 nm or more and 20 μm or less, for example, it can be 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, 1 μm or more, 2 μm or more, or 3 μm or more, and it can also be 20 μm or less, 15 μm or less, 10 μm or less, or 7 μm or less. Here, in this specification, the average particle diameter means the median diameter (D50) calculated based on volume in the laser diffraction method.

[0047] The content ratio of the carbonaceous filler in the composition for the carbon formed body may be 5% by mass or more and 85% by mass or less with respect to the mass of the composition for the carbon formed body. For example, from the viewpoint of maintaining the shape, it is preferable that the content ratio is 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 23% by mass or more. This content ratio may be 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, or 50% by mass or less.

[0048] 《Method for Manufacturing Carbon Formed Body》 The method of the present invention for manufacturing a carbon formed body includes providing a precursor formed body by three-dimensionally printing the above composition, and providing a carbon formed body by carbonizing the precursor formed body by heat-treating the precursor formed body in a non-oxidizing atmosphere. is included.

[0049] 〈Provision of Precursor Formed Body〉 The provision of the precursor formed body is performed by three-dimensionally printing the above composition.

[0050] The method of three-dimensional printing used in the present invention is not particularly limited, and may be, for example, a material extrusion method (thermal melting lamination method) or the like.

[0051] 〈Provision of Carbon Formed Body〉 The provision of the carbon formed body is performed by carbonizing the precursor formed body by heat-treating the precursor formed body in a non-oxidizing atmosphere. By this carbonization, pitch and, in some cases, the thermoplastic resin become amorphous carbon.

[0052] As the non-oxidizing atmosphere, for example, an inert gas atmosphere such as nitrogen gas, argon gas, or helium gas, or a reducing atmosphere such as a hydrogen-containing nitrogen gas may be adopted. Among them, a nitrogen gas atmosphere is preferably used from the viewpoints of easy handling and low cost. Note that the non-oxidizing atmosphere may contain oxygen as long as it can prevent the complete combustion of the layer laminated by three-dimensional printing and cause carbonization. For example, it may contain oxygen in the range of 5% by volume or less, 3% by volume or less, or 1% by volume or less, or may not contain oxygen.

[0053] The temperature of the heat treatment may be 600°C or higher and 1200°C or lower. For example, it may be 600°C or higher, 650°C or higher, 700°C or higher, 750°C or higher, or 800°C or higher, 850°C or higher, or 900°C or higher, and may be 1200°C or lower, 1150°C or lower, 1100°C or lower, 1050°C or lower, or 1000°C or lower.

Examples

[0054] The present invention will be specifically described by examples and comparative examples, but the present invention is not limited thereto.

[0055] The materials shown in Table 1 were kneaded at the contents shown in Table 1 to obtain the compositions of Examples 1 to 4 and Comparative Examples 1 to 2. The details of the materials shown in Table 1 are as follows: MFP-A: Mesophase pitch A (residual carbon rate 50% by mass, softening point 250°C) MFP-B: Mesophase pitch B (residual carbon rate 30% by mass, softening point 90°C) MFP-C: Mesophase pitch C (residual carbon rate 70% by mass, softening point 360°C) PVAc: Polyvinyl acetate resin EtOH: Ethanol

[0056] 《Evaluation》 〈Three-dimensional formability〉 Attempts were made to form each of the obtained carbon forming body compositions using a three-dimensional printer, and the obtained formed bodies were visually confirmed. The evaluation results are as follows: A: The input shape could be output B: Although it was a bit rough, the input shape was almost outputtable. C: The input shape could not be output.

[0057] 〈Shape retention after carbonization〉 By extrusion molding, each composition for a carbon molded body obtained was molded into the shape of a given block body to obtain a precursor molded body for evaluating the shape after carbonization. Next, it was heat-treated at 1000 °C for 50 hours in a non-oxidizing atmosphere to carbonize the resin molded body and obtain a carbon molded body. The shape of the obtained carbon molded body was visually confirmed. The evaluation criteria are as follows: A: A molded body having a shape almost similar to the shape before carbonization was obtained. B: Although some details were lost from the shape before carbonization, an almost similar molded body was obtained. C: A molded body having a shape significantly changed from the shape before carbonization was obtained, or no molded body was obtained.

[0058] The configurations and evaluation results of the examples and comparative examples are shown in Table 1.

[0059]

Table 1

[0060] From Table 1, it can be understood that the compositions of the examples, which contain pitch and the content ratio of the pitch is 10% by mass or more based on the mass of the composition, have good three-dimensional formability and can maintain the shape even after carbonization.

Claims

1. A composition for a carbon formed body for manufacturing a carbon formed body by three-dimensional printer forming and carbonization, containing pitch, wherein the content rate of the pitch is 10% by mass or more with respect to the mass of the composition for a carbon formed body. Composition for a carbon formed body.

2. The composition for a carbon formed body according to Claim 1, wherein the softening point of the pitch is 50°C or higher and 400°C or lower.

3. The composition for a carbon formed body according to Claim 1 or 2, further containing a thermoplastic resin.

4. The composition for a carbon formed body according to Claim 3, wherein the char residue rate of the thermoplastic resin is 30% or less.

5. The composition for a carbon formed body according to Claim 3, wherein the content rate of the thermoplastic resin is 10% by mass or more and 80% by mass or less with respect to the mass of the composition for a carbon formed body.

6. The composition for a carbon formed body according to Claim 1 or 2, further containing a carbonaceous filler.

7. The composition for a carbon formed body according to Claim 6, wherein the carbonaceous filler is at least one selected from the group consisting of graphite and carbon fiber.

8. The composition for a carbon formed body according to Claim 6, wherein the content rate of the carbonaceous filler is 10% by mass or more and 80% by mass or less with respect to the mass of the composition for a carbon formed body.

9. The composition for a carbon formed body according to Claim 1 or 2, wherein the char residue rate of the entire composition for a carbon formed body is 15% or more and 85% or less.

10. A filament for manufacturing a carbon formed body by three-dimensional printer forming and carbonization, which is composed of the composition for a carbon formed body according to Claim 1 or 2.

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