Method for producing carbon fiber precursors and / or carbon fibers

Abstract

To provide a novel technical means that enables the production of carbon fiber precursor fibers and / or carbon fibers while suppressing the generation of CO2. [Solution] A step of preparing a mixture comprising a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in its molecule and which may contain one or more heteroatoms in its molecule, and a solvent, The above mixture is heated under conditions in which the hydrocarbon compound is not oxidized to obtain a polymer solution, The process of spinning the above polymer solution, A method for producing carbon fiber precursor fibers containing [a specific substance].

Description

[Technical Field]

[0001] This disclosure relates to a method for producing carbon fiber precursor fibers and / or carbon fibers. [Background technology]

[0002] Because carbon fiber is lightweight and high-strength, it is widely used in fields such as aircraft and automobiles, energy industries such as wind power generation, and even buildings and sports products, from the perspective of reducing fuel and carbon dioxide (CO2) emissions, and has become one of Japan's key industries. Traditionally, carbon fiber has been manufactured using methods such as synthesis from polyacrylonitrile (PAN) (PAN-based carbon fiber) or synthesis from pitch (pitch-based carbon fiber). Meanwhile, various methods to further improve these conventional carbon fiber manufacturing methods are being investigated.

[0003] For example, Patent Document 1 proposes a method for producing carbon fiber precursor fibers and carbon fibers using a polyvinylacetylene polymer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-240529 Public Relations [Overview of the Initiative]

[0005] However, conventional methods, including the method proposed in Patent Document 1, require crosslinking (flame-retardant treatment or immobilization treatment) of the raw materials by heating at 200-350°C in an oxygen atmosphere (e.g., in air), which has the problem of generating CO or CO2 during subsequent high-temperature heating (e.g., above 700°C).

[0006] A significant increase in demand for carbon fiber is expected in the near future. However, from a carbon neutrality perspective, it is required to reduce CO2 emissions to zero overall by 2050, making carbon fiber manufacturing methods that do not generate CO2 desirable.

[0007] Therefore, one objective of this disclosure is to provide a new technical means that enables the production of carbon fiber precursor fibers and / or carbon fibers while suppressing the generation of CO2.

[0008] The Discloser, through diligent research, unexpectedly discovered that it is possible to produce carbon fiber precursor fibers and / or carbon fibers while suppressing CO2 generation by using compounds having at least two ethynyl groups and / or vinyl groups in the molecule. This disclosure is based on this finding.

[0009] According to one embodiment of the present disclosure, the process involves preparing a mixture comprising a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in the molecule and which may contain one or more heteroatoms in the molecule, and a solvent. The above mixture is heated under conditions in which the hydrocarbon compound is not oxidized to obtain a polymer solution, The process of spinning the above polymer solution, A method for producing carbon fiber precursor fibers, including the above, is provided.

[0010] According to one embodiment of the present disclosure, the step of heating carbon fiber precursor fibers obtained by the method of the present disclosure. A method for producing carbon fiber is provided, including the following.

[0011] According to this disclosure, it becomes possible to manufacture carbon fiber precursor fibers and / or carbon fibers while suppressing the generation of CO2. [Brief explanation of the drawing]

[0012] [Figure 1A] The IR spectrum of the carbon fiber precursor obtained in Example 1 is shown. [Figure 1B]The IR spectrum of the carbon fiber obtained in Example 1 is shown. [Figure 1C] The Raman spectrum of the carbon fiber obtained in Example 1 is shown. [Figure 2A] The IR spectrum of the carbon fiber obtained in Example 2 (26DE) is shown (Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). [Figure 2B] The Raman spectrum of the carbon fiber obtained in Example 2 (26DE) is shown (Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). [Figure 3A] The IR spectrum of the carbon fiber obtained in Example 2 (35DE) is shown (Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). [Figure 3B] The Raman spectrum of the carbon fiber obtained in Example 2 (35DE) is shown ((Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). [Figure 3C] The results of observing the carbon fiber obtained in Example 2 (35DE) with an optical microscope are shown. [Figure 4A] The IR spectrum of the carbon fiber obtained in Example 3 (26DE) is shown (Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). [Figure 4B] The Raman spectrum of the carbon fiber obtained in Example 3 (26DE) is shown ((Experimental: measured value / Calculated: calculated value by Gaussian 16 B3lyp / 6-31g(d)). Detailed description of the invention

[0013] [Method for producing carbon fiber precursor fiber] According to one embodiment of the present disclosure, a step of preparing a mixture comprising a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in the molecule and which may contain one or more heteroatoms in the molecule, and a solvent (also referred to in the present disclosure as the “preparation step”), The above mixture is heated under conditions in which the hydrocarbon compound is not oxidized to obtain a polymer solution (also referred to in this disclosure as the "polymer solution acquisition step"), The process of spinning the above polymer solution (also referred to as the "spinning process" in this disclosure), A method for producing carbon fiber precursor fibers, including the above, is provided. The method of this disclosure will be described in detail below.

[0014] <Preparation process> According to one embodiment of the present disclosure, a preparation step may be performed in a method for producing carbon fiber precursor fibers. In the preparation step, a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in its molecule and possibly containing one or more heteroatoms in its molecule may be mixed with a solvent under any conditions to obtain a mixture, or a mixture of the hydrocarbon compound and solvent that has been mixed in advance may be obtained (for example, a commercially available one).

[0015] According to one embodiment of the present disclosure, the preparation step includes mixing the hydrocarbon compound with the solvent.

[0016] The mixing conditions (temperature, time, pressure, etc.) can be appropriately adjusted by a person skilled in the art depending on the desired carbon fiber precursor fibers and / or carbon fibers.

[0017] (Hydrogen compounds) The hydrocarbon compounds in this disclosure are not particularly limited, as long as they have at least two ethynyl groups and / or vinyl groups in their molecules, and may contain one or more identical or different heteroatoms in their molecules.

[0018] The ethynyl and / or vinyl groups contained within the molecule of the hydrocarbon compound may be located in the side chain or at the terminal. The upper limit of the number of ethynyl and / or vinyl groups that can be contained within the molecule of the hydrocarbon compound is not particularly limited, as long as the objectives of this disclosure can be achieved. The upper limit of the number of ethynyl and / or vinyl groups that can be contained within the molecule of the hydrocarbon compound may vary depending on the structure of the hydrocarbon compound. For example, if the hydrocarbon compound consists of an aromatic ring structure, the upper limit of the number of ethynyl and / or vinyl groups that can be contained within the molecule is considered to be equal to the number of sp2C-H groups.

[0019] According to one embodiment of the present disclosure, the number of ethynyl groups and / or vinyl groups contained in the molecule of the hydrocarbon compound is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and even more preferably 2 to 3.

[0020] According to one embodiment of the present disclosure, the hydrocarbon compound comprises at least two ethynyl groups. The presence of ethynyl groups in the molecule of the hydrocarbon compound is advantageous compared to the hydrocarbon compound comprising only vinyl groups, in that it is easier to produce carbon materials because the amount of residual hydrogen in the raw material is smaller.

[0021] The hydrocarbon compounds described above may consist only of single bonds, or they may contain one or more double and / or triple bonds. The hydrocarbon compounds may have one or more hydrogen atoms bonded to a carbon atom substituted with any substituent (for example, alkyl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, alkoxy groups, halogen groups (e.g., fluorine, chlorine, bromine, iodine)), carboxyl groups, aldehyde groups, hydroxyl groups, amino groups, or phenyl groups, which may be substituted with one or more substituents).

[0022] The heteroatoms that may be contained within the molecule of the hydrocarbon compound described above are not limited to those described above, but include, for example, nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, boron atoms, halogen atoms, and the like. According to one embodiment of the present disclosure, one or more carbon atoms constituting the hydrocarbon compound may be substituted with heteroatoms (e.g., oxygen atoms, nitrogen atoms, sulfur atoms, boron atoms, phosphorus atoms). From the viewpoint of further suppressing the generation of CO2 and / or carbon monoxide (CO) in the manufacturing process of carbon fiber precursor fibers and / or carbon fibers (e.g., heat treatment), it is preferable that the hydrocarbon compound does not contain an oxygen atom within its molecule.

[0023] The above hydrocarbon compounds may include chain structures, branched chain structures, and cyclic structures.

[0024] The cyclic structure that may be included in the above hydrocarbon compound may be monocyclic, polycyclic (e.g., bicyclic, tricyclic, tetracyclic), or spirocyclic. The above cyclic structure may be a 3-10 membered ring (i.e., 3-10 ring atoms), preferably a 4-8 membered ring (i.e., 4-8 ring atoms), and more preferably a 5-7 membered ring (i.e., 5-7 ring atoms). Examples of cyclic structures that may be included in the above hydrocarbon compound include cycloalkyl, cycloalkynyl, heterocycloalkyl, and heterocycloalkenyl rings with 3-40 ring atoms (preferably 4-30, more preferably 5-20); aromatic rings or heteroaromatic rings with 6-40 aromatic ring atoms (preferably 6-30, more preferably 6-20); and so on. Heterocycloalkyl, heterocycloalkenyl, and heteroaromatic rings contain at least one heteroatom (e.g., nitrogen, sulfur, or boron) as a ring atom. In this disclosure, "per ring" means each ring that constitutes a fused ring, in the case of a fused ring. For example, in the case of the naphthalene skeleton, since two 6-membered rings are fused together, "per ring" when referring to the naphthalene skeleton means each 6-membered ring that constitutes the naphthalene skeleton.

[0025] The above hydrocarbon compound preferably contains a cyclic structure, from the viewpoint that it is easier to introduce more cyclic structures into a cyclic material because the carbon material has a cyclic structure. According to one embodiment of the present disclosure, the above hydrocarbon compound contains a cyclic structure within the molecule. According to one embodiment of the present disclosure, the above hydrocarbon compound consists of a cyclic structure which may be substituted with arbitrary substituents. According to one embodiment of the present disclosure, the above cyclic structure is monocyclic, bicyclic, or tricyclic. According to one embodiment of the present disclosure, the above cyclic structure is a 5-7 membered ring per ring. According to one embodiment of the present disclosure, the above cyclic structure is monocyclic, bicyclic, or tricyclic, and is a 5-7 membered ring per ring.

[0026] The above hydrocarbon compounds preferably include aromatic rings and / or heteroaromatic rings as cyclic structures, from the viewpoint that it is easier to introduce more cyclic structures from cyclic material raw materials because the carbon material has a cyclic structure. According to one embodiment of the present disclosure, the above cyclic structure includes aromatic rings and / or heteroaromatic rings (preferably consisting of aromatic rings and / or heteroaromatic rings). According to one embodiment of the present disclosure, the above cyclic structure includes aromatic rings and / or heteroaromatic rings (preferably consisting of aromatic rings and / or heteroaromatic rings), and each ring is a 5-7 membered ring. According to a preferred embodiment of the present disclosure, the above cyclic structure includes aromatic rings and / or heteroaromatic rings having 6-20 aromatic ring atoms (preferably consisting of aromatic rings and / or heteroaromatic rings having 6-20 aromatic ring atoms), and each ring is a 5-7 membered ring.

[0027] According to one embodiment of the present disclosure, in the hydrocarbon compound, an ethynyl group and / or a vinyl group (preferably an ethynyl group) is directly bonded to the cyclic structure.

[0028] According to one embodiment of this disclosure, the hydrocarbon compound has the following structure: [ka] (In the formula, X1 ~X 10 The designation is the same or different for each application, and is CR, N, NR, B, BR, or S (preferably CR or N). Y may be the same or different for each application, and may be NR, BR, or S (preferably NR). R is the same or different for each application and represents a hydrocarbon group which may be substituted with a vinyl group, an ethynyl group, a hydrogen atom, a halogen, or any substituent (preferably a vinyl group, an ethynyl group, a hydrogen atom, or a halogen atom, more preferably an ethynyl group or a hydrogen atom). However, X1~X in the molecule 10 At least three of these are CRs, and at least two of the Rs in the molecule are vinyl groups and / or ethynyl groups (preferably ethynyl groups). It includes at least one selected from the group consisting of the following.

[0029] In this disclosure, "hydrocarbon group" means a group containing carbon and hydrogen (however, the hydrogen atoms may be partially substituted by any substituent). The hydrocarbon group may be linear, branched, or cyclic, and may be saturated or unsaturated. The hydrocarbon group may also contain one or more ring structures. The hydrocarbon group is not particularly limited, but may be C1-C substituted by one or more substituents. 20 A hydrocarbon group (for example, an aliphatic hydrocarbon group such as an alkyl group or an alkenyl group). Such a hydrocarbon group may have one or more nitrogen atoms, oxygen atoms, sulfur atoms, etc., at its terminal or in its molecular chain.

[0030] According to one embodiment of the present disclosure, each ring has at least three carbon atoms as ring atoms.

[0031] According to one embodiment of the present disclosure, the number of heteroatoms as ring atoms per ring is one or less.

[0032] According to one embodiment of the present disclosure, the number of ethynyl groups and / or vinyl groups (preferably ethynyl groups) per ring is 3 or less.

[0033] According to one embodiment of the present disclosure, the hydrocarbon compound has the following structure:

Chemical formula

[0034] According to one embodiment of the present disclosure, the number of ethynyl groups and / or vinyl groups (preferably ethynyl groups) per ring is 3 or less.

[0035] According to one embodiment of the present disclosure, the hydrocarbon compound has the following structure:

Chemical formula

[0036] According to one embodiment of this disclosure, the hydrocarbon compound has the following structure: [ka] [ka] It includes at least one selected from the group consisting of the following.

[0037] (solvent) The solvent is not particularly limited as long as it can achieve the objectives of this disclosure, but examples include water; alcohols such as methanol, ethanol, propanol, and butanol; organic solvents such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), chloroform, dichlorobenzene, dimethylformamide, and dimethylacetamide; and these may be used individually or in any combination of two or more.

[0038] According to one embodiment of the present disclosure, the solvent is such that at least a portion of the hydrocarbon compound is dissolved in it. Dissolving at least a portion of the hydrocarbon compound in the solvent is advantageous in that polymerization can proceed more efficiently.

[0039] The mass ratio (solvent / hydrocarbon compound) of the hydrocarbon compound to the solvent contained in the above mixture is not particularly limited as long as the objectives of this disclosure can be achieved, but may be, for example, 0.1 to 300, preferably 1 to 50, more preferably 3 to 30, and even more preferably 5 to 25.

[0040] <Polymer solution acquisition process> According to one embodiment of the present disclosure, a polymer solution acquisition step may be performed in a method for producing carbon fiber precursor fibers. The method of the present disclosure is advantageous in that at least a portion of the hydrocarbon compound is not oxidized in the polymer solution acquisition step, and therefore the generation of CO2 and / or CO can be suppressed in subsequent heating steps. According to one embodiment of the present disclosure, the polymer solution acquisition step is performed under conditions in which substantially all (preferably all) of the hydrocarbon compound is not oxidized.

[0041] The conditions in the polymer solution acquisition process (temperature, time, heating time, pressure, etc.) are such that at least a portion of the hydrocarbon compound is polymerizable and at least a portion of the hydrocarbon compound is not oxidized. Those skilled in the art can adjust these conditions as appropriate depending on the desired carbon fiber precursor fibers and / or carbon fibers. The process is also applicable in the presence of oxygen (e.g., in an air atmosphere) as long as the temperature is such that at least a portion of the hydrocarbon compound is polymerizable and at least a portion of the hydrocarbon compound is not oxidized. The conditions in the polymer solution acquisition process may be set based on the results of preliminary tests or other studies that determine in advance the conditions under which at least a portion of the hydrocarbon compound is polymerizable and at least a portion of the hydrocarbon compound is not oxidized.

[0042] According to one embodiment of the present disclosure, heating in the polymer solution acquisition process is carried out under an oxygen-free atmosphere. In this disclosure, “oxygen-free atmosphere” means an atmosphere that is substantially free of oxygen (preferably an atmosphere that is completely free of oxygen). The oxygen-free atmosphere may be, for example, an inert gas atmosphere such as nitrogen, argon, or helium. The inert gas may be a single gas or any combination of two or more gases. According to one embodiment of the present disclosure, “substantially oxygen-free atmosphere” may mean, for example, that the oxygen content is less than 1% (preferably less than 0.1%, more preferably less than 0.01%) based on the total volume of the gas. Alternatively, the oxygen-free atmosphere may be under vacuum.

[0043] When heating in the polymer solution acquisition step is carried out in a non-oxygen atmosphere, the temperature can be appropriately adjusted by those skilled in the art, taking into account the time, heating time, pressure, etc., in the polymer solution acquisition step, depending on the desired carbon fiber precursor fibers and / or carbon fibers. The above temperature may be, for example, 320°C or less, preferably 140 to 320°C, more preferably 160 to 290°C, and even more preferably 180 to 270°C. Setting the temperature to 320°C or less is advantageous in that it can promote the polymerization of the hydrocarbon compound while preventing carbonization of the hydrocarbon compound. According to one embodiment of the present disclosure, heating in the polymer solution acquisition step is carried out at a temperature of 320°C or less.

[0044] When heating in the polymer solution acquisition process is carried out under a non-oxygen atmosphere, the time can be appropriately adjusted by those skilled in the art, taking into account the temperature, heating time, pressure, etc., in the polymer solution acquisition process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, the above time may be 0.01 to 24 hours, preferably 0.1 to 10 hours, and more preferably 0.3 to 5 hours.

[0045] When heating in the polymer solution acquisition process is carried out under a non-oxygen atmosphere, the heating time can be appropriately adjusted by those skilled in the art, taking into account the temperature, time, pressure, etc., in the polymer solution acquisition process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. The heating time may be, for example, 200 to 0.01°C / min, preferably 50 to 0.05°C / min, and more preferably 20 to 0.1°C / min.

[0046] When heating in the polymer solution acquisition process is carried out under a non-oxygen atmosphere, the pressure can be appropriately adjusted by those skilled in the art, taking into account the temperature, time, heating time, etc., in the polymer solution acquisition process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. Examples of such pressures include atmospheric pressure and reduced pressure.

[0047] According to one embodiment of the present disclosure, heating in the polymer solution acquisition step is carried out in the presence of a catalyst (preferably, in the presence of both a catalyst and oxygen). Using a catalyst in the polymer solution acquisition step is advantageous in that the polymerization of the hydrocarbon compound can proceed even at lower temperatures.

[0048] In the polymer solution acquisition process, "in the presence of oxygen" may refer to the presence of oxygen at a desired concentration, as long as the desired catalytic activity can be obtained. Furthermore, the presence of oxygen is not particularly limited as long as the objectives of this disclosure can be achieved, and may be oxygen alone or a mixture of oxygen with other gases (but not limited to these, such as nitrogen, argon, or carbon dioxide). According to one embodiment of this disclosure, the presence of oxygen is an air atmosphere.

[0049] (catalyst) The catalysts that can be used in the polymer solution acquisition process are not particularly limited, as long as they can achieve the objectives of this disclosure. Examples of catalysts include copper-containing compounds such as copper chloride, copper acetate, copper nitrate, and copper sulfate, as well as metal-containing compounds such as nickel, cobalt, lithium, and palladium, thermal polymerization initiators, and photopolymerization initiators. These may be used individually or in any combination of two or more.

[0050] The amount of catalyst used is not particularly limited, but for example, 0.0001 to 10 moles, preferably 0.0003 to 3 moles, and more preferably 0.001 to 0.1 moles, may be used per 1 mole of the above hydrocarbon compound. Furthermore, from the viewpoint of eliminating the need to remove the catalyst from the reaction system, the amount of catalyst used may be, for example, 0.0001 to 0.1 moles, preferably 0.0001 to 0.01 moles.

[0051] The catalyst may be removed in a subsequent step if necessary. Methods for removing the catalyst include, for example, filtration, centrifugation, acids or bases, chelating agents, and metal etching agents (ferric chloride, sodium peroxodisulfate, ammonium persulfate).

[0052] When heating in the polymer solution acquisition step is carried out in the presence of a catalyst and oxygen, the temperature can be appropriately adjusted by those skilled in the art, taking into account the time, heating time, pressure, etc., in the polymer solution acquisition step, depending on the desired carbon fiber precursor fibers and / or carbon fibers. The above temperature may be, for example, 160°C or less, preferably 10 to 160°C, more preferably 20 to 150°C, and even more preferably 30 to 140°C. Setting the temperature to 160°C or less is advantageous in that it can promote the polymerization of the hydrocarbon compound while preventing oxidation of the hydrocarbon compound. According to one embodiment of this disclosure, heating in the polymer solution acquisition step is carried out at a temperature of 160°C or less.

[0053] When heating in the polymer solution acquisition step is carried out in the presence of a catalyst and oxygen, the time can be appropriately adjusted by those skilled in the art, taking into account the temperature, heating time, pressure, etc., in the polymer solution acquisition step, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, the above time may be 0.01 to 24 hours, preferably 0.1 to 10 hours, and more preferably 0.3 to 5 hours.

[0054] When heating in the polymer solution acquisition process is carried out in the presence of a catalyst and oxygen, the heating time can be appropriately adjusted by those skilled in the art, taking into account the temperature, time, pressure, etc., in the polymer solution acquisition process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. The heating time may be, for example, 300 to 0.001°C / min, preferably 100 to 0.01°C / min, and more preferably 50 to 0.1°C / min.

[0055] When heating in the polymer solution acquisition process is carried out in the presence of a catalyst and oxygen, the pressure can be appropriately adjusted by a person skilled in the art, taking into account the temperature, time, heating time, etc., in the polymer solution acquisition process, depending on the desired carbon fiber precursor fibers and / or carbon fibers.

[0056] The polymer solution acquisition step may be performed two or more times under different conditions (e.g., different temperatures, times, pressures, etc.). For example, the polymer solution acquisition step may be performed two or more times at different temperatures. Alternatively, the polymer solution acquisition step may be performed two or more times in the presence of a catalyst and in the absence of a catalyst. Performing the polymer solution acquisition step two or more times under different conditions is advantageous in that it may yield carbon fiber precursor fibers and / or carbon fibers with higher strength.

[0057] (Polymer solution) According to one embodiment of the present disclosure, the polymer solution comprises a polymer of the hydrocarbon compound, the solvent, and optionally the hydrocarbon compound (i.e., the hydrocarbon compound remaining unpolymerized).

[0058] The degree of polymerization of the polymer contained in the polymer solution is not particularly limited and can vary depending on the hydrocarbon compound used and the conditions in the polymer acquisition process. For example, the degree of polymerization may be 50 to 1,000,000, preferably 100 to 500,000, and more preferably 200 to 200,000.

[0059] The concentration of the polymer contained in the polymer solution is not particularly limited, as long as it is a concentration that allows for spinning in the spinning process described later. From the viewpoint of spinning more efficiently in the spinning process described later, the concentration of the polymer contained in the polymer solution may be, for example, 5 to 90% by mass, preferably 10 to 80% by mass, and more preferably 20 to 70% by mass, based on the total mass of the polymer solution. If the polymer solution obtained in the polymer solution acquisition step deviates from the above range of polymer concentration, the viscosity of the polymer solution may be adjusted in the viscosity adjustment step described later to bring the concentration of the polymer in the polymer solution within the above range.

[0060] The polymer solution may contain other components as needed, as long as they do not impair the purpose of this disclosure.

[0061] <Viscosity adjustment process> According to one embodiment of the present disclosure, a step of adjusting the viscosity of the polymer solution (also referred to in the present disclosure as a "viscosity adjustment step") may be performed in a method for producing carbon fiber precursor fibers. Performing a viscosity adjustment step is advantageous in that it allows for more efficient spinning of the carbon fiber precursor fibers in the spinning step described later. According to one embodiment of the present disclosure, the viscosity adjustment step may be performed to increase the viscosity of the polymer solution.

[0062] The conditions in the viscosity adjustment process (temperature, time, pressure, etc.) can be appropriately adjusted by a person skilled in the art depending on the desired carbon fiber precursor fibers and / or carbon fibers.

[0063] The temperature in the viscosity adjustment process can be appropriately adjusted by those skilled in the art, taking into account the time, pressure, solvent used, etc., in the viscosity adjustment process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, when DMSO is used as the solvent, the temperature may be 70 to 180°C, preferably 80 to 160°C, and more preferably 90 to 150°C. When a solvent with a low boiling point, such as THF, is used, the temperature may be 25 to 100°C, preferably 30 to 80°C, and more preferably 35 to 70°C.

[0064] The time required for the viscosity adjustment process can be appropriately adjusted by those skilled in the art, taking into account the temperature, pressure, solvent used, etc., in the viscosity adjustment process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, when DMSO is used as the solvent, the time may be 0.01 to 48 hours, preferably 0.1 to 24 hours, and more preferably 0.3 to 12 hours. When a solvent with a low boiling point, such as THF, is used, the time may be 0.001 to 24 hours, preferably 0.01 to 10 hours, and more preferably 0.1 to 4 hours.

[0065] Those skilled in the art can appropriately adjust the pressure in the viscosity adjustment process, taking into account the temperature, time, etc., depending on the desired carbon fiber precursor fibers and / or carbon fibers. Examples of such pressures include atmospheric pressure and reduced pressure. From the viewpoint of more efficiently adjusting the viscosity of the polymer solution, reduced pressure is preferable.

[0066] The viscosity adjustment process may be carried out, for example, under an oxygen atmosphere (e.g., air), a non-oxygen atmosphere (e.g., nitrogen, argon), or under reduced pressure. Carrying the process under reduced pressure allows for efficient removal of the solvent, which is advantageous from the standpoint of improving work efficiency.

[0067] <Spinning Process> According to one embodiment of the present disclosure, a spinning step may be performed in a method for producing carbon fiber precursor fibers. The spinning step is not particularly limited as long as it is a method capable of spinning the obtained polymer solution. Typically, in the spinning step, the polymer solution is spun from a spinneret and solidified to obtain carbon fiber precursor fibers.

[0068] The diameter of the discharge hole of the spinneret can be appropriately adjusted by a person skilled in the art, depending on the desired diameter of the carbon fiber precursor fiber and / or carbon fiber. The diameter of the discharge hole of the spinneret may be, for example, 0.01 to 1 mm, preferably 0.02 to 0.6 mm, and more preferably 0.03 to 0.4 mm. For example, if the discharge hole is an injection needle, a gauge of 28 to 38 G, preferably 30 to 38 G, and more preferably 32 to 38 G may be used.

[0069] The spinning method is not limited to these, but examples include wet spinning, wet-dry spinning, dry spinning, gel spinning, flash spinning, and electrospinning. From the viewpoint of reducing manufacturing costs or achieving a smaller fiber diameter to improve strength, the spinning method is preferably wet spinning, electrospinning, etc., and is particularly preferably wet spinning. According to one embodiment of this disclosure, the spinning process includes wet spinning.

[0070] A typical wet spinning method involves extruding a polymer solution into a coagulation bath solution through a hole having a predetermined pore size (e.g., a spinneret) to obtain carbon fiber precursor fibers (preferably coagulated yarn).

[0071] (coagulation bath solution) The coagulation bath solution is not particularly limited, as long as it is capable of spinning carbon fiber precursor fibers. According to one embodiment of the present disclosure, the coagulation bath solution comprises water (e.g., tap water, purified water, or deionized water).

[0072] According to one embodiment of the present disclosure, the coagulation bath solution comprises water and another solvent. Examples of other solvents include alcohols such as methanol, ethanol, propanol, and butanol; organic solvents such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), chloroform, dichlorobenzene, and N,N-dimethylformamide, which may be used individually or in any combination of two or more.

[0073] If the coagulation bath solution contains water and the other solvents mentioned above, the mass ratio (other solvent / water) may be, for example, 0.005 to 200, preferably 0.05 to 50, and more preferably 0.2 to 10.

[0074] The temperature of the coagulation bath solution is not particularly limited as long as it is at a temperature at which carbon fiber precursor fibers can be spun. For example, the above temperature may be -50 to 90°C, preferably -40 to 70°C, and more preferably -30 to 50°C.

[0075] In the spinning process, spinning may be carried out while tensile strength is applied as needed. Alternatively, the obtained carbon fiber precursor fibers may be tensile strength at any time after the spinning process, as needed. The tensile strength can be appropriately adjusted by those skilled in the art depending on the desired carbon fiber precursor fibers and / or carbon fibers. By tensile strength in this way, carbon fiber precursor fibers and / or carbon fibers can be obtained.

[0076] (Carbon fiber precursor fibers) In this disclosure, "carbon fiber precursor fiber" means a precursor fiber that can be converted into carbon fiber. Carbon fiber precursor fiber can typically be converted into carbon fiber by heat treatment.

[0077] Carbon fiber precursor fibers may be single fibers (filaments) or fiber bundles. In this disclosure, when carbon fiber precursor fibers are fiber bundles, they may be referred to as "carbon fiber precursor fiber bundles." Carbon fiber precursor fiber bundles can be obtained by bundling multiple carbon fiber precursor fibers together. In carbon fiber precursor fiber bundles, the number of filaments per bundle is not particularly limited, but may be, for example, 50 to 96,000, preferably 100 to 48,000, and more preferably 500 to 36,000.

[0078] According to one embodiment of the present disclosure, carbon fiber precursor fibers are for the production of carbon fibers.

[0079] <Drying process> According to one embodiment of the present disclosure, in a method for producing carbon fiber precursor fibers, a step of drying the obtained carbon fiber precursor fibers (also referred to in the present disclosure as a "drying step") may be performed. Performing a drying step is advantageous from the viewpoint of being able to remove at least a portion of the solvent and other substances remaining in the obtained carbon fiber precursor fibers and / or to further increase the degree of polymerization of the polymer constituting the obtained carbon fiber precursor fibers (i.e., further promote polymerization). Furthermore, performing a drying step at a lower temperature before carbonization under high temperature heating (e.g., 500°C or higher) in the production of carbon fibers described later is advantageous from the viewpoint of being able to obtain carbon fiber precursor fibers and / or carbon fibers with higher strength.

[0080] The conditions in the drying process (temperature, time, heating time, pressure, etc.) can be appropriately adjusted by a person skilled in the art depending on the desired carbon fiber precursor fibers and / or carbon fibers.

[0081] Those skilled in the art can appropriately adjust the temperature during the drying process, taking into account the drying time, heating time, pressure, etc., depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, the temperature may be 30 to 480°C, preferably 120 to 450°C, more preferably 140 to 400°C, and even more preferably 160 to 350°C.

[0082] Those skilled in the art can appropriately adjust the drying time, taking into account the temperature, heating time, pressure, etc., during the drying process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, the above time may be 0.01 to 24 hours, preferably 0.1 to 10 hours, and more preferably 0.2 to 3 hours.

[0083] Those skilled in the art can appropriately adjust the heating time in the drying process by considering the temperature, time, pressure, etc., in the drying process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. For example, the heating time may be 0.01 to 300°C / min, preferably 0.1 to 100°C / min, and more preferably 0.05 to 10°C / min.

[0084] Those skilled in the art can appropriately adjust the pressure during the drying process, taking into account the temperature, time, heating time, etc., during the drying process, depending on the desired carbon fiber precursor fibers and / or carbon fibers. Examples of such pressures include atmospheric pressure and reduced pressure. From the viewpoint of more efficiently increasing the degree of polymerization of the polymer constituting the carbon fiber precursor fibers, reduced pressure is preferable.

[0085] The drying process may be carried out, for example, under an oxygen atmosphere (e.g., air) or under a non-oxygen atmosphere (e.g., under nitrogen or argon). From the viewpoint of more efficiently increasing the degree of polymerization of the polymer constituting the carbon fiber precursor fibers, it is preferable that the drying process be carried out under a non-oxygen atmosphere (e.g., under nitrogen or argon).

[0086] The drying process may be carried out two or more times under different temperatures, times, and pressures. For example, the drying process may be carried out two or more times under different temperatures. Carrying out the drying process two or more times under different conditions is advantageous in that it may yield carbon fiber precursor fibers and / or carbon fibers with higher strength.

[0087] In the method for producing carbon fiber precursor fibers according to this disclosure, other steps (e.g., sizing agent application step, water washing step, oil application step, functional group application step, etc.) may be performed as necessary, in addition to the steps described above. Such other steps may be performed at any time before or after the steps described above, or at the same time as the steps described above.

[0088] [Method for manufacturing carbon fiber] According to one embodiment of the present disclosure, the process involves heating carbon fiber precursor fibers obtained by the method of the present disclosure (also referred to in the present disclosure as the "precursor fiber heating process"). A method for producing carbon fiber is provided, including the following.

[0089] <Precursor fiber heating process> The precursor fiber heating step is typically a step that promotes carbonization. Therefore, according to one embodiment of the present disclosure, the precursor fiber heating step is a carbonization step.

[0090] The conditions in the precursor fiber heating process (temperature, time, heating time, pressure, etc.) can be appropriately adjusted by a person skilled in the art depending on the desired carbon fiber precursor fiber and / or carbon fiber.

[0091] Those skilled in the art can appropriately adjust the temperature in the precursor fiber heating process, taking into account the time, heating time, pressure, etc., in the precursor fiber heating process, depending on the desired carbon fiber. For example, the temperature may be 400 to 3000°C, preferably 50 to 3000°C, more preferably 600 to 3000°C, and even more preferably 700 to 3000°C.

[0092] As for the time in the precursor fiber heating process, those skilled in the art can appropriately adjust it by considering the temperature, heating time, pressure, etc., in the precursor fiber heating process, depending on the desired carbon fiber. For example, the above time may be 0.1 to 24 hours, preferably 0.5 to 16 hours, and more preferably 1 to 12 hours.

[0093] As for the heating time in the precursor fiber heating process, those skilled in the art can appropriately adjust it by considering the temperature, time, pressure, etc., in the precursor fiber heating process, depending on the desired carbon fiber. The heating time may be, for example, 0.1 to 1000°C / min, preferably 0.5 to 500°C / min, and more preferably 1 to 100°C / min.

[0094] Those skilled in the art can appropriately adjust the pressure in the precursor fiber heating process, taking into account the temperature, time, heating time, etc., depending on the desired carbon fiber. Examples of such pressures include atmospheric pressure and reduced pressure.

[0095] The precursor fiber heating process may be carried out, for example, under an oxygen atmosphere (e.g., air) or under a non-oxygen atmosphere (e.g., under nitrogen or argon).

[0096] The precursor fiber heating process may be carried out two or more times at different temperatures, times, and pressures. For example, the precursor fiber heating process may be carried out two or more times at different temperatures. Carrying out the precursor fiber heating process two or more times under different conditions is advantageous from the viewpoint of obtaining carbon fibers with higher strength.

[0097] <Carbon fiber> The carbon fibers obtained in this disclosure may be single fibers (filaments) or fiber bundles. In this disclosure, when the carbon fibers are fiber bundles, they may be referred to as "carbon fiber bundles." Carbon fiber bundles can be obtained by bundling multiple carbon fibers together. In carbon fiber bundles, the number of filaments per bundle is not particularly limited, but may be, for example, 50 to 96,000, preferably 100 to 48,000, and more preferably 500 to 36,000.

[0098] The diameter of the carbon fibers obtained by the method disclosed herein is not particularly limited and can be appropriately adjusted by those skilled in the art depending on the application. For example, the diameter of the carbon fibers may be such that the average diameter (average fiber diameter) of a single fiber is 0.01 to 100 μm, preferably 0.05 to 80 μm, and more preferably 0.08 to 60 μm. The diameter of the carbon fibers can be determined by a test method in accordance with JIS R7607 "Carbon Fibers - Test Method for Diameter and Cross-sectional Area of ​​Single Fibers". The carbon fibers may be long fibers or short fibers. The average fiber length of the carbon fibers is not particularly limited, but is, for example, 100 mm or less. The average values ​​of diameter and fiber length can be calculated, for example, based on 100 carbon fibers arbitrarily selected from those obtained by the method disclosed herein.

[0099] The carbon fibers obtained by the method disclosed herein can be used for any application. For example, the carbon fibers can be used as structural materials for vehicles and buildings, electromagnetic shielding materials, flame retardant materials, and heat insulating materials; for water purification, air purification, gas adsorption, water treatment, decolorization, cigarette filters, and cleanroom filters; for secondary batteries; for electrolytic capacitors; and for electrode materials for fuel cells and electric double-layer capacitors. In addition, the carbon fibers may be processed together with resins, ceramics, metals, etc., to form carbon fiber reinforced materials that can be used as structural materials for vehicles, buildings, bridges, etc., and for electromagnetic shielding materials.

[0100] [Raw material composition] According to another embodiment of the present disclosure, a raw material composition is provided for the production of carbon fiber precursor fibers or carbon fibers, comprising a hydrocarbon compound or a polymer thereof having at least two ethynyl groups and / or vinyl groups in the molecule and which may contain one or more heteroatoms in the molecule, wherein the hydrocarbon compound comprises a cyclic structure in the molecule.

[0101] The above raw material composition may contain a hydrocarbon compound as defined in this disclosure (provided that it includes a cyclic structure in its molecule), or a polymer thereof (i.e., a polymer obtained by heating the hydrocarbon compound in a manner similar to, for example, the polymer solution acquisition step of this disclosure), or both.

[0102] The amount of the hydrocarbon compound or its polymer contained in the above raw material composition is not particularly limited. For example, the amount of the hydrocarbon compound or its polymer contained in the above raw material composition may be 1 to 100% by mass, preferably 10 to 100% by mass, and more preferably 30 to 100% by mass, based on the total mass of the above raw material composition.

[0103] The above raw material composition may contain not only the hydrocarbon compound but also other components as needed. Examples of such other components include the solvent mentioned above.

[0104] This disclosure includes the following: [1] A step of preparing a mixture comprising a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in the molecule and which may contain one or more heteroatoms in the molecule, and a solvent, The above mixture is heated under conditions in which the hydrocarbon compound is not oxidized to obtain a polymer solution, The process of spinning the above polymer solution, A method for producing carbon fiber precursor fibers containing [a specific substance]. [2] The method according to [1], wherein the hydrocarbon compound has a cyclic structure within the molecule. [3] The method according to [2], wherein the ethynyl group and / or vinyl group are directly bonded to the cyclic structure. [4] The method according to [2], wherein the ring structure is mono-ring, bi-ring, or tri-ring. [5] The method according to [2], wherein the above-mentioned cyclic structure is a 5-7 membered ring per ring. [6] The method according to [2], wherein the cyclic structure comprises an aromatic ring and / or a heteroaromatic ring. [7] The above hydrocarbon compound has the following structure: [ka] (In the formula, X 1 ~X 10 These may be the same or different for each application, and may be CR, N, NR, B, BR, or S. Y may be the same or different for each application, and is NR, BR, or S. R is the same or different for each application and represents a hydrocarbon group which may be substituted with a vinyl group, an ethynyl group, a hydrogen atom, a halogen, or any substituent. However, X1~X in the molecule 10 (At least three of these are CRs, and at least two of the Rs in the molecule are vinyl groups and / or ethynyl groups.) A method according to any one of [1] to [6], comprising at least one selected from the group consisting of the following. [8] The method according to any one of [1] to [7], wherein the heating in the step of obtaining the polymer solution is carried out in a non-oxygen atmosphere. [9] The method according to any one of [1] to [7], wherein the heating in the step of obtaining the polymer solution is carried out in the presence of a catalyst. A step of heating carbon fiber precursor fibers obtained by any of the methods in

[10] , [1], and [9]. A method for producing carbon fiber, including [the specified element].

[11] A raw material composition for the production of carbon fiber precursor fibers or carbon fibers, comprising a hydrocarbon compound or a polymer thereof having at least two ethynyl groups and / or vinyl groups in the molecule and which may contain one or more heteroatoms in the molecule, wherein the hydrocarbon compound comprises a cyclic structure in the molecule. [Examples]

[0105] The methods of this disclosure will be described in more detail below using examples. However, the following examples are not intended to limit the methods of this disclosure in any way. Unless otherwise specified, the percentages and ratios described herein are in terms of mass. Unless otherwise specified, the units and measurement methods described herein are in accordance with the provisions of the Japanese Industrial Standards (JIS).

[0106] [Example 1: Production of carbon fiber 1 (compounds that do not contain heteroatoms)] 3 g of 1,3,5-triethinylbenzene (135TEB) was dissolved in 60 g of solvent (dimethyl sulfoxide (DMSO)) and placed in a separable flask (reaction vessel). Nitrogen gas was bubbling into the solution (80 mL / min, 1 hour). The reaction vessel was placed in an oil bath set to 453 K (180 °C), 473 K (200 °C), or 503 K (230 °C), and the mixture was reacted for 3 hours with stirring at 200 rpm to obtain a polymer solution. The obtained polymer solution was heated under reduced pressure at 120-140 °C for 6-8 hours to adjust its viscosity. The viscosity-adjusted polymer solution was placed in a syringe and spun into a coagulation bath (80 mL) prepared with a water:DMSO ratio of 4:1 using a 32 G needle to obtain carbon fiber precursor fibers. These carbon fiber precursor fibers were dried under reduced pressure in a vacuum dryer at 180 °C for 1 hour. The obtained carbon fiber precursor fibers were measured by infrared absorption spectroscopy (instrument: FT-IR-4200, detector: MCT_M, manufactured by JASCO Corporation) to obtain IR spectra. The results are shown in Figure 1A. The obtained samples are denoted as 135TEB_polymer preparation temperature (K) (for example, a sample reacted at 453K (180°C) is denoted as "135TEB_453"). Furthermore, for 135TEB_503, the obtained carbon fiber precursor fibers were heated under reduced pressure at 573-1273K (300-1000°C) to obtain carbon fibers. The obtained carbon fibers were measured by infrared absorption spectroscopy and Raman spectroscopy (instrument: NRS-4500, manufactured by JASCO Corporation, laser wavelength: 532nm) to obtain IR spectra and Raman spectra. The results are shown in Figures 1B and 1C. In addition, the obtained carbon fibers were observed with an optical microscope (instrument: Intel Play QX3+, manufactured by Mattel, magnification: 60). The obtained carbon fibers are denoted as 135TEB_polymer preparation temperature (K)_heating temperature (K) (for example, carbon fiber precursor fibers obtained by reacting at 503K (230°C) and then heated at 573K (300°C) are denoted as "135TEB_503_573").

[0107] [Example 2: Production of carbon fiber 2 (compounds containing heteroatoms)] 2,6-Diethynylpyridine (26DE) or 3,5-Diethynylpyridine (35DE) dissolved in DMSO was placed in a separable flask and heated in an oil bath at 473K (200°C) for 1 to 3 hours under a flow of nitrogen gas to obtain a polymer solution. The obtained polymer solution was heated under reduced pressure at 140°C to adjust its viscosity, and then spun by extrusion into a coagulation bath in the same manner as in Example 1 to obtain carbon fiber precursor fibers. The obtained carbon fiber precursor fibers were dried under reduced pressure at approximately 220°C for 1 hour and then placed in a glass tube. Subsequently, the carbon fiber precursor fibers were heated under reduced pressure at 573K (300°C), 773K (500°C), and 1273K (1000°C) in that order for 1 hour each to obtain carbon fibers (heating rate: 10K / min). The obtained carbon fiber precursor fibers and carbon fibers were measured in the same manner as in Example 1 to obtain IR spectra and Raman spectra. The results are shown in Figures 2A to 3B. Furthermore, the obtained carbon fiber precursor fibers and carbon fibers were observed using an optical microscope in the same manner as in Example 1. The results are shown in Figure 3C. The obtained carbon fibers are denoted as raw material_heating temperature (K) (for example, if 35DE is used as the raw material, polymerization is carried out at 473K (200℃), and then heated further at 573K (300℃), it will be denoted as "35DE_473_573").

[0108] [Example 3: Carbon Fiber Manufacturing 3 (Using Heteroatom-Containing Compounds / Catalysts)] 0.02 mmol of copper chloride (CuCl) and 0.02 mmol of N,N,N',N'-tetramethylethylenediamine (TMEDA) were added to 50 mL of DMSO and stirred for 15 minutes. Then, 8 mmol of 26DE dissolved in 35 mL of DMSO was added to the container and stirred (100 rpm) for 1.5 hours in an oil bath at 393 K (120 °C) under an air atmosphere to obtain a polymer solution. In the case of 0.02 mmol of CuCl, metal removal treatment was not performed due to the small amount of catalyst, but if necessary, metal components can be removed using hydrochloric acid or the like. After heating, the solution was moderately dried under reduced pressure at 373 K to increase its viscosity, and then spun by injecting it into a 20% by mass DMSO aqueous solution. This was dried under reduced pressure at 373K (100℃) for 1 hour, then placed in a glass tube and heated under reduced pressure at 573K (300℃), 773K (500℃), and 1273K (1000℃) in that order for 1 hour each. The resulting carbon fibers are denoted as raw material_Cu_stirring time (1.5h)_heating temperature (K).

[0109] In Example 1, heating at a temperature of 300°C (573K) or higher resulted in an IR spectrum of 2070–2210 cm⁻¹. -1 The peak originating from the ethynyl group disappears (Figure 1B), and heating at temperatures above 600°C (873K) causes the G band of the Raman spectrum (generally with a peak top at 1500-1700 cm⁻¹) to disappear. -1 (within this range), D-band (generally the peak top is 1300-1400cm) -1 (within the range of), and / or 2D bands and 2G bands, etc. (generally with a peak top of 2600-3300 cm) -1 A peak appeared within the specified range (Figure 1C). In this technical field, the G band is understood to be due to the graphite structure (vibration of the 6-membered ring), and the D band is understood to be due to defects and / or disturbances in the graphite structure. The peak top is 1600 cm. -1In the above cases, it may be referred to as the D' band (a G band shifted due to a defect). Furthermore, in the art, the 2G band is understood to be due to the harmonics of the G band, and the 2D band is understood to be due to the harmonics of the D band. In the art, carbon fibers are generally considered to have been obtained when the G band and / or D band appear (preferably the G band and D band appear) and a carbon fiber-like appearance (for example, an appearance in which the fiber shape is preserved). From the results of Example 1, it is clear that carbon fibers were obtained, as G-bands and / or D-bands appeared and a carbon fiber-like appearance was observed (not shown) (Figures 1A to 1C). Furthermore, in the method of Example 1, the polymer solution is obtained using nitrogen gas (i.e., under a non-oxygen atmosphere), so it is considered that there is little to no generation of CO2 and / or CO during subsequent heating.

[0110] Although not bound by theory, in Example 1, as the heating temperature of 135 TEB increases, the temperature rises from 980 to 1030 cm². -1 sp that appears 2 The increased relative peak intensity derived from CH suggests that the polymerization reaction is proceeding via the polyene-forming pathway (Figure 1A). Although not bound by theory, the appearance of G-band and / or D-band peaks in the Raman spectrum at heating above 600°C (873K) suggests that the ethynyl group reacted, leading to further carbonization.

[0111] From the results of Example 2, 2100cm -1 The peaks originating from the ethynyl group in the vicinity weakened with heating above 200°C (473K), and almost disappeared or were completely absent with heating above 1000°C (1273K) (Figures 2A and 3A). Although not constrained by theory, it is thought that the ethynyl group reacted, and subsequent carbonization proceeded further. Furthermore, from the results of Example 2, while no peak was observed in the raw materials (26DE, 35DE) due to the effect of fluorescence, a peak of 1500-1600 cm was observed when heated at 200°C (473K) and 300°C (573K). -1 A slight peak was observed, and when heated to temperatures above 500°C (773K), the G-band and / or D-band peaks were clearly observed (Figures 2B and 2C). Although not constrained by theory, it is thought that heating above 500°C makes it easier for carbon fibers to form. From the results of Example 2, it is clear that carbon fibers were obtained, as G-bands and / or D-bands appeared and the material exhibited a carbon fiber-like appearance (Figures 2A to 3C). In the method of Example 2, the polymer solution was obtained using nitrogen gas (i.e., under a non-oxygen atmosphere), so it is considered that there was little to no generation of CO2 and / or CO during subsequent heating.

[0112] From the results of Example 3, it can be seen that using a catalyst allows for a lower reaction temperature (393K) and a reaction yield of 1000-1600 cm³ compared to when no catalyst is used. -1 The peak is broadened, suggesting that the reaction is promoted even at low temperatures (Figure 4A). Furthermore, because the reaction time was short (1.5 hours), peaks originating from the raw materials were also observed (Figure 4A). Additionally, the use of the catalyst resulted in the slight appearance of the G band and / or D band after polymerization at a lower temperature (393K (120°C)) compared to the case without the catalyst, suggesting that the polymerization reaction proceeded with the use of the catalyst (Figure 4B).

[0113] Conventional methods required flame-retardant treatment in an oxygen atmosphere, which not only generated CO2 and / or CO during subsequent heat treatment (e.g., carbonization treatment), but also resulted in the consumption of carbon atoms, leading to a problem of reduced carbon fiber yield. On the other hand, according to this disclosure, heating under conditions that prevent oxidation of the hydrocarbon compounds used as raw materials eliminates the need for flame-retardant treatment, which was essential in conventional methods. Furthermore, according to this disclosure, since flame-retardant treatment (which is known to require expensive equipment) is unnecessary, expensive equipment is not required, which is advantageous in that carbon fibers can be manufactured at a low cost. In addition, according to this disclosure, since flame-retardant treatment, which requires a long processing time, is unnecessary, it is possible to shorten the manufacturing time of carbon fibers and / or improve workability. Moreover, according to this disclosure, since the generation of CO2 and / or CO can be suppressed, the yield of carbon fibers can be improved, which is advantageous.

Claims

1. A step of preparing a mixture comprising a hydrocarbon compound having at least two ethynyl groups and / or vinyl groups in its molecule and which may contain one or more heteroatoms in its molecule, and a solvent, The process involves heating the mixture under conditions in which the hydrocarbon compound is not oxidized to obtain a polymer solution, The process of spinning the polymer solution, A method for producing carbon fiber precursor fibers containing [a specific substance].

2. The method according to claim 1, wherein the hydrocarbon compound includes a cyclic structure within the molecule.

3. The method according to claim 2, wherein the ethynyl group and / or vinyl group are directly bonded to the cyclic structure.

4. The method according to claim 2, wherein the annular structure is mono-ring, bi-ring, or tri-ring.

5. The method according to claim 2, wherein the annular structure has 5 to 7 member rings per ring.

6. The method according to claim 2, wherein the cyclic structure comprises an aromatic ring and / or a heteroaromatic ring.

7. The hydrocarbon compound has the following structure: 【Chemistry 1】 (In the formula, X １ ~X １０ These may be the same or different for each application, and are CR, N, NR, B, BR, or S. Y may be the same or different for each application, and may be NR, BR, or S. R is the same or different for each application and represents a hydrocarbon group which may be substituted with a vinyl group, an ethynyl group, a hydrogen atom, a halogen, or any substituent. However, X in the molecule １ ~X １０ (At least three of these are CR groups, and at least two of the R groups in the molecule are vinyl groups and / or ethynyl groups.) The method according to claim 1, comprising at least one selected from the group consisting of

8. The method according to claim 1, wherein the heating in the step of obtaining the polymer solution is carried out in a non-oxygen atmosphere.

9. The method according to claim 1, wherein the heating in the step of obtaining the polymer solution is carried out in the presence of a catalyst.

10. A step of heating carbon fiber precursor fibers obtained by the method described in claims 1 to 9. A method for producing carbon fiber, including [the specified element].

11. A raw material composition for the production of carbon fiber precursor fibers or for the production of carbon fibers, comprising a hydrocarbon compound or a polymer thereof having at least two ethynyl groups and / or vinyl groups in the molecule and possibly containing one or more heteroatoms in the molecule, wherein the hydrocarbon compound contains a cyclic structure in the molecule.

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