Resin composition for manufacturing carbon molding by three-dimensional printer molding and carbonization

Abstract

To provide a resin composition which can be molded with a three-dimensional printer and can maintain its shape after carbonization.SOLUTION: A resin composition for manufacturing a carbon molding by three-dimensional printer molding and carbonization contains a first thermoplastic resin having a residual carbon ratio of less than 50%, a second thermoplastic resin having a residual carbon ratio of 50% or more, and a carbonaceous filler dispersed in the thermoplastic resins.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition for a 3D printer, particularly a resin composition that can be molded by a 3D printer and can maintain its shape during carbonization.

Background Art

[0002] A 3D (three-dimensional) 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 a complex three-dimensional structure 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 called additive manufacturing materials), various materials have been developed according to the type and application of 3D printers. As the 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 bath 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) are becoming more affordable 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] Fused deposition modeling (FDM) is a method of creating objects by first fluidizing a thermoplastic resin, which has a thread-like shape called a filament, using a heating mechanism inside the extrusion head, then extruding it from a nozzle onto a platform, and gradually layering it according to the cross-sectional shape of the desired object while it cools and solidifies.

[0006] Various resin compositions have been disclosed for such fused deposition modeling (FDM) 3D printers.

[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, which is a molding material for 3D printers.

[0008] Patent Document 2 discloses a filament for a fused deposition modeling (FDM) 3D printer, characterized in that it is formed from a functional resin composition comprising a thermoplastic matrix resin and functional nanofillers dispersed in the thermoplastic matrix resin. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2018 / 043231 [Patent Document 2] Japanese Patent Publication No. 2016-28847 [Overview of the project] [Problems that the invention aims to solve]

[0010] Conventional 3D printers could produce molded bodies that were primarily resin-based.

[0011] In contrast, the present invention provides a resin composition that can be molded by a 3D printer, and which allows for the production of a carbonized molded body by carbonizing the resulting molded body. [Means for solving the problem]

[0012] The inventors, after diligent research, discovered that the above problems could be solved by the following means, and thus completed the present invention. That is, the present invention is as follows: <Aspect 1> A resin composition for the production of carbon molded articles by 3D printing and carbonization, A first thermoplastic resin with a carbon residue rate of less than 50%, A second thermoplastic resin having a carbon residue rate of 50% or more, and Carbonaceous fillers dispersed in these thermoplastic resins A resin composition containing [the specified substance]. <Aspect 2> The resin composition according to Aspect 1, wherein the melt mass flow rate conforming to JIS K7210-1 is 10 to 35 g / 10 min or more when measured under conditions of a temperature of 360°C and a load of 2.16 kgf. <Aspect 3> The resin composition according to aspect 1 or 2, wherein the melting point of the first thermoplastic resin is higher than the melting point of the second thermoplastic resin, as measured by differential thermal-thermogravimetric analysis (TG-DTA) under conditions of a nitrogen atmosphere and a heating rate of 10°C / min. <Aspect 4> The resin composition according to any one of aspects 1 to 3, wherein the thermal decomposition temperature of the first thermoplastic resin, as measured by differential thermal-thermogravimetric analysis (TG-DTA) under conditions of a nitrogen atmosphere and a heating rate of 10°C / min, is lower than the thermal decomposition temperature of the second thermoplastic resin. <Aspect 5> The resin composition according to any one of aspects 1 to 4, wherein both the first and second thermoplastic resins are polyimide resins. <Aspect 6> The resin composition according to aspect 5, wherein the first thermoplastic resin is a thermoplastic polyimide. <Aspect 7> The resin composition according to aspect 5 or 6, wherein the first thermoplastic resin is polyetherimide. <Aspect 8> The resin composition according to any one of Aspects 1 to 7, wherein the content of the carbonaceous filler is 10 to 40% by mass based on the mass of the entire resin composition. <Aspect 9> The resin composition according to any one of Aspects 1 to 8, wherein the carbonaceous filler is carbon fiber.

Advantages of the Invention

[0013] According to the present invention, a resin composition that can be molded by a 3D printer and a carbon molded body can be obtained by carbonizing the obtained molded body can be obtained.

Modes for Carrying Out the Invention

[0014] 《Resin Composition》 The resin composition of the present invention for the production of a carbon molded body by 3D printer molding and carbonization A first thermoplastic resin having a char residue rate of less than 50%, A second thermoplastic resin having a char residue rate of 50% or more, and A carbonaceous filler dispersed in these thermoplastic resins is contained.

[0015] That is, the present invention also relates to the use of the above resin composition for the production of a carbon molded body by 3D printer molding and carbonization.

[0016] Here, regarding the present invention, the "char residue rate" is a value measured as follows.

[0017] (Char Residue Rate) 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 8�0 °C is taken as the mass after firing, and the char residue rate (mass%) is calculated by the following formula. Char residue rate (%) = (mass after firing (850 °C) / mass before firing) × 100

[0018] The inventors have found that, with the above configuration, a resin composition can be obtained that can be molded by a 3D printer and can maintain its shape after carbonization. Without wishing to be bound by theory, this is thought to be because the combination of the first thermoplastic resin with a low char yield and the carbonaceous filler contributes to maintaining the shape before carbonization even after carbonization, while the second thermoplastic resin with a high char yield contributes to the moldability by a 3D printer.

[0019] The melt mass flow rate of the resin composition of the present invention, measured under the conditions of a temperature of 360°C and a load of 2.16 kgf in accordance with JIS K7210-1, may be 10 g / 10 min or more, 12 g / 10 min or more, 15 g / 10 min or more, 17 g / 10 min or more, or 20 g / 10 min or more, and may also be 100 g / 10 min or less, 70 g / 10 min or less, 50 g / 10 min or less, 40 g / 10 min or less, 35 g / 10 min or less, or 30 g / 10 min or less.

[0020] The melting point of the resin composition of the present invention may be 300°C or more, 310°C or more, 320°C or more, 330°C or more, 340°C or more, 350°C or more, 360°C or more, or 370°C or more, and may also be 450°C or less, 440°C or less, 430°C or less, 420°C or less, 410°C or less, 400°C or less, 390°C or less, or 380°C or less.

[0021] The thermal decomposition temperature of the resin composition of the present invention may be 380°C or more, 390°C or more, 400°C or more, 410°C or more, or 420°C or more, and may also be 550°C or less, 540°C or less, 530°C or less, 520°C or less, 510°C or less, or 500°C or less.

[0022] In this invention, the melting point and thermal decomposition temperature can be measured by differential thermal-thermogravimetric analysis (TG-DTA) under conditions of a nitrogen atmosphere and a heating rate of 10°C / min. Specifically, by heating the sample under a nitrogen atmosphere at a heating rate of 10°C / min and performing differential thermal-thermogravimetric analysis (TG-DTA) in accordance with JIS K0129, a curve with mass on the vertical axis and temperature on the horizontal axis (TG curve) and a curve with temperature difference on the vertical axis and temperature on the horizontal axis (DTA curve) can be obtained, thereby obtaining the melting point and thermal decomposition temperature. More specifically, the temperature at which an endothermic peak is observed in the DTA curve at a position where no decrease in mass is observed in the TG curve, and where this minimum value is taken, can be defined as the melting point. Furthermore, when a decrease in mass is observed in the TG curve, the temperature at which the decrease in mass begins can be defined as the thermal decomposition temperature.

[0023] It is preferable that the first and second thermoplastic resins are of the same type, and in particular, both are polyimide-based resins, from the viewpoint of ensuring good mixing of the first and second thermoplastic resins and thereby improving moldability by 3D printing.

[0024] Furthermore, the resin composition of the present invention may contain other particles of choice besides carbonaceous fillers.

[0025] The following describes each component of the present invention.

[0026] <First Thermoplastic Resin> The first thermoplastic resin is a thermoplastic resin having a carbon residue rate of less than 50%. This carbon residue rate may be 48% or less, 45% or less, 42% or less, 40% or less, 38% or less, or 35% or less, and may also be 15% or more, 18% or more, 20% or more, 22% or more, or 25% or more.

[0027] As the first thermoplastic resin, for example, thermoplastic polyimide (TPI) can be used. Commercially available thermoplastic polyimides can be used.

[0028] From the viewpoint of obtaining a molded article after carbonization, the content of the first thermoplastic resin is preferably 10% by mass or 15% by mass or more, relative to the total mass of the resin composition. This content may be 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less.

[0029] The melt mass flow rate of the first thermoplastic resin, in accordance with JIS K7210-1, may be 0.1 g / 10 min or more, 0.5 g / 10 min or more, or 1.0 g / 10 min or more when measured at a temperature of 360 °C and a load of 2.16 kgf, 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.

[0030] The melting point of the first thermoplastic resin may be 250°C or higher, 260°C or higher, 270°C or higher, 280°C or higher, 290°C or higher, 300°C or higher, 310°C or higher, or 315°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, or 325°C or lower.

[0031] The melting point of the first thermoplastic resin may be higher than the melting point of the second thermoplastic resin, for example, it may be 20°C or more, 30°C or more, 40°C or more, 50°C or more, or 55°C or more higher than the melting point of the second thermoplastic resin.

[0032] The thermal decomposition temperature of the first thermoplastic resin 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.

[0033] The thermal decomposition temperature of the first thermoplastic resin may be lower than the thermal decomposition temperature of the second thermoplastic resin, for example, it may be 20°C or more, 30°C or more, 40°C or more, 50°C or more, or 55°C or more lower than the thermal decomposition temperature of the second thermoplastic resin.

[0034] <The second type of thermoplastic resin> The second thermoplastic resin is a thermoplastic resin having a carbon residue rate of 50% or more. This carbon residue rate may be 52% or more, 55% or more, 57% or more, 60% or more, or 62% or more, and may also be 80% or less, 78% or less, 75% or less, 72% or less, 70% or less, or 67% or less.

[0035] From the viewpoint of obtaining the above-mentioned effects, it is preferable that the carbon residue rate of the second thermoplastic resin is 20% or more, 25% or more, 30% or more, or 35% or more greater than the carbon residue rate of the first thermoplastic resin.

[0036] For example, polyetherimide (PEI) can be used as the second thermoplastic resin. Commercially available polyetherimides can be used. In particular, when thermoplastic polyimide (TPI) is used as the first thermoplastic resin, polyetherimide (PEI) is used as the second thermoplastic resin, and both the first and second thermoplastic resins are imide-based resins, thus providing high compatibility between the first and second thermoplastic resins.

[0037] From the viewpoint of moldability by a 3D printer, the content of the second thermoplastic resin is preferably 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, relative to the total mass of the resin composition. This content may be 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less.

[0038] The melt mass flow rate of the second thermoplastic resin, in accordance with JIS K7210-1, may be 5 g / 10 min or more, 7 g / 10 min or more, 10 g / 10 min or more, or 12 g / 10 min or more when measured at a temperature of 340 °C and a load of 5.00 kgf, and may also be 30 g / 10 min or less, 25 g / 10 min or less, 20 g / 10 min or less, 17 g / 10 min or less, or 15 g / 10 min or less.

[0039] The melting point of the second thermoplastic resin may be 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, 250°C or higher, or 260°C or higher, and may also be 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, or 270°C or lower.

[0040] The thermal decomposition temperature of the second thermoplastic resin may be 400°C or higher, 410°C or higher, 420°C or higher, 430°C or higher, 440°C or higher, 450°C or higher, 460°C or higher, or 470°C or higher, and may also be 550°C or lower, 540°C or lower, 530°C or lower, 520°C or lower, 510°C or lower, 500°C or lower, 490°C or lower, or 480°C or lower.

[0041] <Carbonaceous filler> The carbonaceous filler may be carbon fibers and / or carbon particles dispersed in the first and second thermoplastic resins. In the carbon molded article obtained after carbonization, this carbonaceous filler will be dispersed in amorphous carbon. Among these, the use of carbon fibers is preferred from the viewpoint of maintaining the shape of the molded article obtained after carbonization.

[0042] Examples of carbon fibers, though not limited to those mentioned, include milled fibers and chopped fibers. These may be used individually or in combination.

[0043] The average length of the carbon fibers may 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 may 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.

[0044] The average fiber diameter of the carbon fibers can be 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and 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 50 or more fibers using a scanning electron microscope (SEM), observing and measuring them, and calculating the average length per fiber.

[0045] Examples of carbon particles include graphene, carbon nanotubes, graphite, and carbon black. These may be used individually or in combination.

[0046] The shape of the carbon particles is not particularly limited and may be flattened, in array form, spherical, or other shapes.

[0047] The average particle diameter of carbon particles 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 can also be 20 μm or less, 15 μm or less, 10 μm or less, or 7 μm or less. Herein, in this specification, the average particle diameter refers to the median diameter (D50) calculated on a volume basis in the laser diffraction method.

[0048] From the viewpoint of maintaining shape, the carbonaceous filler content in the resin composition is preferably 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total mass of the resin composition. This content may be 45% by mass or less, 40% by mass or less, or 35% by mass or less.

[0049] <Other particles> Other particles besides carbonaceous fillers can be used, for example, resin particles, metal particles, etc.

[0050] As resin particles, for example, acrylic resin particles can be used. As acrylic resin particles, for example, particles of poly(meth)acrylic acid, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, polybutyl(meth)acrylate, polyisobutyl acrylate, polypentyl(meth)acrylate, polyhexyl(meth)acrylate, poly-2-ethylhexyl(meth)acrylate, etc. can be used.

[0051] As metallic particles, for example, at least one selected from the group consisting of particles of elemental metals, metal oxides, metal carbides, and metal nitrides can be used, and in particular, particles of elemental metals can be used. More specifically, at least one selected from the group consisting of particles of elemental titanium (Ti), tungsten (W), molybdenum (Mo), iron (Fe), aluminum (Al), copper (Cu), silver (Ag), and gold (Au), as well as oxides, carbides, and nitrides, can be used.

[0052] The average particle diameter of other particles can be 10 nm or more, 20 nm or more, 30 nm or more, 50 nm or more, 70 nm or more, 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, or 1 μm or more, and can also be 5.0 μm or less, 4.0 μm or less, 3.0 μm or less, 2.0 μm or less, 1.5 μm or less, or 1.3 μm or less. Here, the method for measuring this average particle diameter can be found in the description concerning carbonaceous fillers.

[0053] The content of other particles in the resin composition may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, and may also be 45% by mass or less, 40% by mass or less, or 35% by mass or less, based on the total mass of the resin composition.

[0054] Method for manufacturing carbon molded bodies The present invention's method for producing a carbon molded body is To provide a resin molded product by 3D printing the above resin composition, and By heat-treating the aforementioned resin molded body in a non-oxidizing atmosphere, the resin molded body is carbonized to provide a carbonized molded body. Includes.

[0055] <Provision of resin molded products> The resin molded product is provided by 3D printing the above-mentioned resin composition.

[0056] The 3D printing method used in the present invention is not particularly limited and may be, for example, a material extrusion method (fused deposition modeling method).

[0057] <Provision of carbon molded bodies> The carbonized molded body is provided by carbonizing the resin molded body by heat-treating it in a non-oxidizing atmosphere.

[0058] As a non-oxidizing atmosphere, for example, an inert gas atmosphere such as nitrogen gas, argon gas, or helium gas, or a reducing atmosphere such as hydrogen-containing nitrogen gas may be used, and among these, a nitrogen gas atmosphere is preferred from the viewpoint of being easy to handle and inexpensive. The non-oxidizing atmosphere may contain oxygen in a range that prevents complete combustion of the layers laminated by 3D printing and allows for 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 it may not contain oxygen at all.

[0059] The heat treatment temperature may be, for example, 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]

[0060] The present invention will be specifically described by examples and comparative examples, but the present invention is not limited thereto.

[0061] Preparation of resin compositions The materials shown in Table 1 were kneaded in the proportions shown in Table 1 to obtain the resin compositions of Examples 1-2 and Comparative Examples 1-3. Details of the materials shown in Table 1 are as follows: TPI: Unrefined thermoplastic polyimide (carbon residue 24.1%) PEI: Polyetherimide (carbon residue rate 59.9%) Carbon fiber: Carbon fiber (length 30-200 μm, average fiber diameter approximately 8 μm)

[0062] The melting point and thermal decomposition temperature of the obtained resin composition were measured by differential thermal-thermogravimetric analysis (TG-DTA) at a heating rate of 10°C / min under a nitrogen atmosphere.

[0063] Furthermore, the melt mass flow rate (MFR) of the obtained resin composition was measured under conditions of 360°C and a load of 2.16 kgf (only for Comparative Example 2, under conditions of 340°C and a load of 5.00 kgf).

[0064] "evaluation" <3D formability> Each of the obtained resin compositions was subjected to molding using a 3D printer, and the resulting molded bodies were visually inspected. The evaluation results are as follows: A: The input shape was output correctly. B: The input shape could not be output.

[0065] <Maintaining shape after carbonization> Each resin composition obtained was molded into a given block shape by extrusion molding to obtain resin molded bodies for evaluating the shape after carbonization. Next, the resin molded bodies were heat-treated at 1000°C for 50 hours in a non-oxidizing atmosphere to carbonize them and obtain carbon molded bodies. The shape of the obtained carbon molded bodies was visually confirmed. The evaluation criteria are as follows: A: A molded body with a shape nearly identical to the shape before carbonization was obtained. B: A molded body with a shape significantly different from its shape before carbonization was obtained, or no molded body was obtained.

[0066] Table 1 shows the configurations and evaluation results of the examples and comparative examples.

[0067] [Table 1]

[0068] Table 1 shows that the first and second thermoplastic resins, as well as the resin compositions of Examples 1 and 2 containing carbonaceous fillers, exhibit good three-dimensional moldability and maintain their shape even after carbonization.

Claims

1. A resin composition for producing a carbon molded body by three-dimensional printer molding and carbonization, a first thermoplastic resin having a carbon residue rate of less than 50%; A second thermoplastic resin having a carbon residue rate of 50% or more; and Carbonaceous fillers dispersed in these thermoplastic resins A resin composition comprising:

2. The resin composition according to claim 1, wherein the melt mass flow rate according to JIS K7210-1 is 10 to 35 g / 10 min or more when measured under conditions of a temperature of 360 ° C. and a load of 2.16 kgf.

3. 3. The resin composition according to claim 1, wherein the melting point of the first thermoplastic resin is higher than the melting point of the second thermoplastic resin, as measured by simultaneous differential thermal analysis (TG-DTA) under a nitrogen atmosphere at a heating rate of 10°C / min.

4. The resin composition according to any one of claims 1 to 3, wherein the thermal decomposition temperature of the first thermoplastic resin is lower than the thermal decomposition temperature of the second thermoplastic resin, as measured by simultaneous differential thermal analysis (TG-DTA) under a nitrogen atmosphere at a heating rate of 10 ° C. / min.

5. The resin composition according to any one of claims 1 to 4, wherein the first and second thermoplastic resins are both polyimide-based resins.

6. The resin composition according to claim 5 , wherein the first thermoplastic resin is a thermoplastic polyimide.

7. The resin composition according to claim 5 or 6, wherein the first thermoplastic resin is a polyetherimide.

8. The resin composition according to any one of claims 1 to 7, wherein the content of the carbonaceous filler is 10 to 40 mass% with respect to the mass of the entire resin composition.

9. The resin composition according to any one of claims 1 to 8, wherein the carbonaceous filler is a carbon fiber.