JP7157679B2 - Method for producing carbon material, carbon material, and carbon material composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a carbon material, a carbon material, and a carbon material composition.

In recent years, carbon materials such as carbon nanotubes, fullerenes, graphite, graphene, graphene oxide, reduced graphene oxide, artificial graphite, and carbon black have become novel functional materials in various fields due to their characteristic physical properties. (For example, Non-Patent Documents 1-3).

Graphene is a two-dimensional sheet-like carbon material, and has a structure covered with six-membered rings of sp2 carbon. Graphite usually indicates a laminated structure of two or more layers in which two-dimensional sheet-like graphenes are bonded to each other by van der Waals force, but one layer of graphite may also be referred to as graphene.

The existence of graphene has been known for a long time, but until recently, a method for extracting a single sheet of graphene from graphite had not been established. In 2004, it was discovered that graphene flakes could be obtained by peeling off the surface of highly oriented anhydrous graphite with an adhesive tape and attaching the peeled product onto a substrate. Aiming for cost production, graphene production methods by gas phase film formation methods such as CVD (chemical vapor deposition film formation method) and graphene (reduced graphene oxide: RGO) production by reduction of graphene oxide (GO) methods are being considered.

However, the method of producing graphene by a gas-phase film-forming method such as CVD (chemical vapor deposition film-forming method) has the problem that it cannot be obtained in a form other than a film (typically, a bulk form), and combustible gas There is a problem that the metal is contained as an impurity because the film is formed on a metal substrate having catalytic performance such as Cu.

On the other hand, a method for producing graphene (reduced graphene oxide: RGO) by a reduction method of graphene oxide (GO) has recently been studied as a production method that can solve the above problems.

Reduced graphene oxide (RGO) can be typically produced by oxidizing graphite to produce graphene oxide and reducing the resulting graphene oxide. However, in this production method, impurities such as nitrogen, sulfur, phosphorus, and metals other than alkali metals derived from oxidizing agents, reducing agents, and catalysts are mixed in, and the total content of carbon and oxygen in all elements is reduced. As a result, there is a problem that it is difficult to obtain highly pure reduced graphene oxide.

Incidentally, a method for easily producing a graphite film without using combustible gas has recently been reported (Patent Document 1). However, this graphite film also has a problem that it cannot be obtained in a form other than a film (typically in a bulk form).

JP 2017-132648 A

Nature, 354, p. 56-58 (1991) Science, 306, p. 666-669 (2004) Riichiro Saito, "State-of-the-Art Technology and Widespread Applications of Graphene", Chapter 2. Basic physical properties of graphene, 3. Optoelectronic properties of graphene

The applicant of the present application has made intensive studies to develop a novel carbon material that can solve the above conventional problems. Specifically, it has the same or similar crystal structure as graphene, and has almost the same structure as reduced graphene oxide in that it is an almost single-layer oxygen-containing carbon material. A novel carbon material that is different from reduced graphene oxide in that it does not substantially contain elements other than oxygen and is different from graphite in terms of crystal structure, and is carbon that can solve the above conventional problems. Research has been conducted on materials and methods of making such carbon materials.

That is, an object of the present invention is to have a structure that is the same as or similar to graphene in terms of crystal structure, and has almost the same structure as reduced graphene oxide in that it is an almost single-layer oxygen-containing carbon material. And unlike reduced graphene oxide in that it does not substantially contain elements other than oxygen, it differs from graphite in terms of its crystal structure, and the content of impurities such as nitrogen, sulfur, phosphorus, and metals other than alkali metals is reduced. An object of the present invention is to provide a novel carbon material which has a very low proportion and can exist in a form other than a film (typically in a bulk form). A further object is to provide a novel carbon material composition containing such a novel carbon material. Another object of the present invention is to provide a method for producing such a novel carbon material.

The method for producing a carbon material of the present invention comprises:
An aromatic ring-containing compound (A) composed of carbon, hydrogen and oxygen and having a molecular weight of 500 or less is calcined at a temperature of 700° C. or higher.

In one embodiment, the condensation reaction temperature of the aromatic ring-containing compound (A) is 400°C or lower.

In one embodiment, when TG-DTA analysis is performed on the aromatic ring-containing compound (A) under a nitrogen gas atmosphere at a temperature rising condition of 10 ° C./min from 40 ° C., the initial temperature at 50 ° C. A weight ratio (M500/M50) of the weight M500 at a temperature of 500° C. to the weight M50 is 0.2 or more.

In one embodiment, the aromatic ring-containing compound (A) is an aromatic compound having a hydroxyl group.

In one embodiment, the firing temperature is 1000°C to 1500°C.

In one embodiment, in the method for producing a carbon material of the present invention, it can be produced in a bulk state.

The carbon material of the present invention is
Raman analysis shows G-band, D-band and G'-band,
XRD analysis shows no peaks derived from graphite,
XPS analysis shows that the total content of carbon and oxygen in all elements is 99.9% or more,
According to XRF analysis, the percentage contents of nitrogen, sulfur, phosphorus and metals other than alkali metals are each less than 100 ppm.

In one embodiment, the carbon material of the present invention exhibits D+D' and/or 2D' bands by Raman analysis.

In one embodiment, the carbon material of the present invention can exist in a bulk state.

The carbon material composition of the present invention contains the carbon material described above.

In one embodiment, the carbon material composition of the present invention contains a solvent.

In one embodiment, the carbon material is dispersed in the solvent.

In one embodiment, the carbon material composition of the present invention contains a resin.

In one embodiment, the carbon material is dispersed in the resin.

According to the present invention, the crystal structure is the same as or similar to graphene, and the structure is almost the same as that of reduced graphene oxide in that it is an almost single-layer oxygen-containing carbon material. Unlike reduced graphene oxide in that it does not substantially contain elements other than It is possible to provide novel carbon materials that are very low and can exist in forms other than films (typically in bulk). Furthermore, a novel carbon material composition containing such a novel carbon material can be provided. Also, a method for producing such a novel carbon material can be provided.

1 is a Raman analysis result of a carbon material obtained in Example 1. FIG. 4 is the XRD analysis result of the carbon material obtained in Example 1. FIG. 4 shows Raman analysis results of the carbon material obtained in Comparative Example 1. FIG. 4 shows XRD analysis results of the carbon material obtained in Comparative Example 1. FIG. 4 shows XRD analysis results of the carbon material obtained in Comparative Example 2. FIG.

<<Manufacturing method of carbon material>>
In the method for producing a carbon material of the present invention, an aromatic ring-containing compound (A) composed of carbon, hydrogen, and oxygen and having a molecular weight of 500 or less is fired at a temperature of 700° C. or higher.

Thus, the method for producing a carbon material of the present invention is a method for producing a "specific aromatic ring-containing compound" at a "specific temperature" by "firing rather than film formation".

The firing temperature is preferably 700°C to 2000°C, more preferably 800°C to 1800°C, even more preferably 900°C to 1600°C, and particularly preferably 1000°C to 1500°C. If the firing temperature is within the above range, the total content of carbon and oxygen in all elements is very high, and the content of impurities such as nitrogen, sulfur, phosphorus, and metals other than alkali metals is low. New carbon materials can be produced that are very low and can also exist in forms other than films (typically bulk).

In the production method of the present invention, preferably, it can be produced in a bulk state. Specifically, in the production method of the present invention, the aromatic ring-containing compound (A) is preferably heated in bulk. In general, the properties possessed by the bulk are the inherent properties of the material. That is, a substance in its bulk state can determine the values of its fundamental properties, such as boiling point, melting point, viscosity, density, and the like. The physical properties of a substance refer to the properties possessed by the bulk portion. Examples of bulk states are particles, pellets, films, and the like. Examples of the state of existence of particles include powder. The film is preferably a self-supporting film. Heating the aromatic ring-containing compound (A) in a bulk state means, for example, heating particles (powder) made of the aromatic ring-containing compound (A), particles (for example, powder) made of the aromatic ring-containing compound (A) ) is molded into a pellet or film by compression molding or the like, and then the molded body is heated. contain the act. When heating particles (for example, powder) or compacts, for example, they may be placed in a container and heated. Any appropriate container can be adopted as the container. As such a container, for example, it is preferable to use a material that does not substantially deteriorate at the heating temperature. In addition, it is preferable that the surface with which the particles (for example, powder) and the compact come into contact is made of a material that does not chemically react with the aromatic ring-containing compound (A) when heated. A carbon material can be obtained by heating particles (e.g., powder) or molded bodies under preferable conditions, and in the heating step, the aromatic ring-containing compound (A) near the melting point ( A) may melt and become liquid. Such a process is also included in "heating the aromatic ring-containing compound (A) in bulk". On the other hand, as an example that is not "heated in bulk" in the sense of the present invention, for example, the aromatic ring-containing compound (A) is dissolved in a solvent and applied to an arbitrary substrate to form a film. A method of forming a thin film by heating together with a substrate, a chemical vapor deposition (CVD) method, a physical vapor deposition method (PVD), a thin film vapor deposition heating method, and the like. A thin film generally means a film having a thickness of 1 μm or less.

As a heating method, a firing furnace such as a tubular furnace or a box furnace, a heating reaction apparatus using a heat medium, a heating reaction apparatus using microwaves, or the like can be used. Heating can be performed under vacuum, under normal pressure, under pressure, or the like. As for the conditions of the heating atmosphere, the heating can be performed in the air, in an inert gas atmosphere, or the like. The heating atmosphere is preferably an inert gas atmosphere such as nitrogen or argon.

Any suitable heating time can be adopted depending on the molecular weight, solubility, dispersibility, etc. required for the carbon material to be produced. Such heating time is, for example, preferably 1 minute to 48 hours, more preferably 15 minutes to 24 hours, still more preferably 30 minutes to 12 hours, and particularly preferably 1 hour to 10 hours. is.

The aromatic ring-containing compound (A) is an aromatic ring-containing compound composed of carbon, hydrogen and oxygen and having a molecular weight of 500 or less.

The aromatic ring-containing compound (A) may be a single compound or a mixture of two or more compounds. When the aromatic ring-containing compound (A) is a mixture of two or more compounds, at least one compound in the mixture may have the physical properties, structures, etc. described in the present invention. Various conditions such as the heating temperature and the heating time may be determined based on the results.

The aromatic ring-containing compound (A) is composed of carbon, hydrogen and oxygen. Here, "composed of carbon, hydrogen and oxygen" means that the elements constituting the molecular structure itself of the aromatic ring-containing compound (A) are carbon, hydrogen and oxygen.

The aromatic ring-containing compound (A) has a molecular weight of 500 or less, preferably 50-500, more preferably 75-450, even more preferably 80-400, and particularly preferably 100-350. If the molecular weight of the aromatic ring-containing compound (A) is within the above range, the total content of carbon and oxygen in all elements is very high, and impurities such as nitrogen, sulfur, phosphorus, and metals other than alkali metals are reduced. A novel carbon material can be produced that has a very low percentage content and can also exist in forms other than films (typically in bulk form). In addition, if the molecular weight of the aromatic ring-containing compound (A) is within the above range, it can move freely in the carbonization process because of its low molecular weight, and the reactivity can be high. There are also process merits such as less generation of organic gas, which is a by-product in the carbonization process.

The aromatic ring-containing compound (A) is preferably solid and has a melting point at 23°C. Since it has a melting point, it melts during the firing process, and the intermolecular reaction proceeds favorably. If it does not have a melting point, it will not melt during the firing process, so the positions of the molecules will be fixed, the reaction between molecules will be difficult to promote, and it will be difficult to convert it into a carbon material. The reaction can be accelerated by employing such an aromatic ring-containing compound (A). In addition, the solubility of the obtained carbon material in the solvent can be improved (for example, more components of the carbon material can be dissolved in the solvent, or the types of solvents in which the carbon material can be dissolved increase).

The aromatic ring-containing compound (A) typically undergoes a condensation reaction between the same molecules and/or between different molecules by heating.

In the aromatic ring-containing compound (A), the skeleton that does not contribute to condensation preferably has an aromatic structure. By having an aromatic skeleton, the carbon component of the resulting carbon material can be made more stable. As such aromatic structures, aromatic structures composed of carbon atoms such as benzene, naphthalene, anthracene, phenanthrene, and triphenylene are preferred.

As the aromatic ring-containing compound (A), an aromatic compound having a hydroxyl group is particularly preferred. By adopting an aromatic compound having a hydroxyl group as the aromatic ring-containing compound (A), the total content of carbon and oxygen in all elements is much higher, and nitrogen, sulfur, phosphorus, and metals other than alkali metals A new carbon material can be produced that has a much lower content of impurities such as , and can also exist in forms other than films (typically in bulk).

As the aromatic ring-containing compound (A), an aromatic ring-containing compound having a highly symmetrical structure is particularly preferable. By adopting an aromatic ring-containing compound having a highly symmetrical structure as the aromatic ring-containing compound (A), the total content of carbon and oxygen in all elements is much higher, and nitrogen, sulfur, phosphorus, and alkali New carbon materials can be produced that have a much lower content of impurities such as metals other than metals and that can also exist in forms other than films (typically in bulk form).

Any appropriate condensation reaction temperature can be adopted as the condensation reaction temperature of the aromatic ring-containing compound (A) as long as the effects of the present invention are not impaired. Such a condensation reaction temperature is preferably 400° C. or less, more preferably 200° C. to 370° C., and most preferably 250° C. to 350° C. in terms of allowing the effects of the present invention to be exhibited more effectively. . By initiating carbonization at such a low temperature, it is possible to suppress decomposition side reactions that are thought to occur at higher temperatures.

TG-DTA analysis of the aromatic ring-containing compound (A) under a nitrogen gas atmosphere from 40 ° C. under the condition of temperature increase of 10 ° C./min, weight at temperature 500 ° C. relative to initial weight M50 at temperature 50 ° C. The weight ratio of M500 (M500/M50) is preferably 0.2 or more, more preferably 0.2 to 0.9, most preferably 0.2 or more, more preferably 0.2 to 0.9, from the viewpoint that the effects of the present invention can be further exhibited. 3 to 0.8. By using the aromatic ring-containing compound (A) in which the weight ratio (M500/M50) falls within the above range, the effect of the present invention can be further exhibited.

<Representative Embodiment of Aromatic Ring-Containing Compound (A) (Embodiment 1)>
A typical embodiment (Embodiment 1) of the aromatic ring-containing compound (A) is an aromatic ring-containing compound that is decomposed by heating to generate radicals on the aromatic ring. Aromatic ring-containing compounds in which radicals are generated on the aromatic rings undergo a condensation reaction between the same molecules and/or between different molecules, and can become a carbon material.

The aromatic ring-containing compound that is decomposed by heating to generate radicals on the aromatic ring is preferably an aromatic ring-containing compound that generates a gas (a gas in a gaseous state at normal temperature and normal pressure) by heating.

As the aromatic ring-containing compound that generates gas when heated, any appropriate aromatic compound can be employed as long as it is an aromatic ring-containing compound that generates gas when heated. At least one selected from CO, CO ₂ , O ₂ and H ₂ is preferable as the gas that is in a gaseous state at normal temperature and pressure.

Examples of aromatic compounds that generate CO and/or CO ₂ upon heating include aromatic compounds having a "-C(=O)-" and/or "-O-C(=O)-" structure (e.g. , aromatic ketone derivatives, aromatic ester derivatives, acid anhydrides, etc.).

Examples of aromatic compounds that generate CO and/or CO ₂ upon heating include the following compounds.

Examples of aromatic compounds that generate O ₂ upon heating include aromatic compounds having an “—O—O—” structure (eg, aromatic carbon oxides, aromatic peroxides, etc.).

Examples of aromatic compounds that generate O ₂ by heating include the following compounds. In the compounds below, R represents a hydrogen atom, or an optionally substituted alkyl group, aryl group, or heteroaryl group.

Aromatic compounds that generate H ₂ by heating include, for example, condensed polycyclic aromatic compounds having a “—CH ₂ —” structure (eg, phenalene compounds, etc.).

Examples of aromatic compounds that generate H ₂ upon heating include the following compounds.

Aromatic ring-containing compounds that are decomposed by heating to generate radicals on the aromatic ring have decomposability by heating, and at least part of the skeleton is separated and decomposed to form gas molecules (preferably CO, CO ₂ , At least one selected from O ₂ and H ₂ ) is produced, and a radical is produced on the remaining aromatic ring. By using such an aromatic ring-containing compound, a reaction occurs only by decomposition of itself without the need for a reaction catalyst. It is possible to suppress the formation of significant impurities and obtain a carbon material of higher quality. Moreover, by using such an aromatic ring-containing compound, a carbon material can be obtained without using a combustible gas. Also, such aromatic ring-containing compounds may have high reactivity that does not require catalysis.

<Representative Embodiment of Aromatic Ring-Containing Compound (A) (Embodiment 2)>
A representative embodiment (embodiment 2) of the aromatic ring-containing compound (A) is a compound in which one neutral molecule is formed and eliminated from two or more groups by a condensation reaction. In Embodiment 2, one compound may have two or more groups, or two or more groups may be combined to form two or more groups. may be Such an aromatic ring-containing compound (A) can cause a condensation reaction between identical molecules and/or different molecules to become a carbon material.

As the condensation reaction, any appropriate condensation reaction may be adopted as long as it is a condensation reaction in which one neutral molecule is formed from two or more groups and then eliminated, as long as it does not impair the effects of the present invention. obtain. By setting it as such a condensation reaction, it may become possible to react at a comparatively low temperature. Such condensation reactions include, for example,
(a) a condensation reaction by the formation and elimination of H ₂ O from —H and —OH groups;
(b) a condensation reaction by the formation and elimination of ROH from a -H group and a -OR group (where R is any suitable substituted or unsubstituted alkyl group);
(c) condensation reaction by formation and elimination of RCOOH from -H group and -OOCR group (R is any suitable substituted or unsubstituted alkyl group);
etc. In particular, if the desorbed neutral component is a gaseous component at the desorption temperature (firing temperature), it will not be incorporated into the carbon material and will remain in the gaseous phase, and thus will not easily become an impurity.

As a representative example of the condensation reaction, the condensation reaction (above (a)) in which H ₂ O is formed and eliminated from —H group and —OH group will be described.

One embodiment of the aromatic ring-containing compound (A) in Embodiment 2 (sometimes referred to as embodiment (X)) is a compound (a1) having a skeleton consisting of one carbon six-membered ring structure or two A compound (a2) having a skeleton in which the above six-membered ring structures are bonded and/or condensed, half of the substituents not contributing to the structure formation of the skeleton are —OH groups, and the other half is a -H group.

In embodiment (X),
(i) when the aromatic ring-containing compound (A) is a compound (a1) having a skeleton consisting of one carbon six-membered ring structure,
(ii) when the aromatic ring-containing compound (A) is a compound (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed,
Either of the two cases can be adopted.

In embodiment (X), the "substituent that does not contribute to the formation of the skeleton structure" is the "skeleton consisting of one carbon six-membered ring structure" in the case of (i) above, or the case of (ii) above. means a substituent that does not contribute to the structure formation of the skeleton of the "skeleton in which two or more carbon six-membered ring structures are bonded and/or condensed". For example, in the case of (i) above, when the compound (a1) having a skeleton consisting of one carbon six-membered ring structure is represented by the chemical formula (a1-1) shown later, one carbon six-membered ring structure The substituents that do not contribute to the structure formation of the skeleton consisting of are 6 —OH groups and 6 —H groups, and the compound (a1) having a skeleton consisting of one carbon 6-membered ring structure is shown later In the case represented by the chemical formula (a1-2), three —OH groups and three —H groups are substituents that do not contribute to the structure formation of the skeleton consisting of one carbon six-membered ring structure. Further, for example, as the case of (ii) above, when a compound (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed is represented by the following chemical formula (a2-1) , 6 —OH groups and 6 —H groups are substituents that do not contribute to the structure formation of the skeleton in which two or more carbon 6-membered ring structures are bonded and/or condensed.

In the embodiment (X), half of the substituents not contributing to the structure formation of the skeleton of the compound (a1) having a skeleton consisting of one carbon 6-membered ring structure are —OH groups. Half of the substituents that are -H groups and do not contribute to the structure formation of the skeleton of the compound (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed are half the number -OH groups and the other half are -H groups. By having such a substituent structure, the aromatic ring-containing compound (A) can effectively cause dehydration reaction between identical molecules and/or different molecules by heating.

The aromatic ring-containing compound (A) that can be employed in Embodiment (X) includes a compound (a1) having a skeleton consisting of one carbon 6-membered ring structure or two or more carbon 6-membered ring structures bonded and/or Or if it is a compound (a2) having a condensed skeleton, half of the substituents not contributing to the structure formation of the skeleton are —OH groups, and the other half are —H groups, Any suitable compound can be employed as long as it does not impair the effects of the present invention. Examples of such aromatic ring-containing compound (A) include the following compounds.

Among the aromatic ring-containing compounds (A) that can be employed in the embodiment (X), it is presumed that the condensation reaction is likely to occur due to the formation and elimination of H ₂ O from the —H group and the —OH group. Phloroglucinol (compound (a1-2)) and hexahydroxytriphenylene (HHTP) (compound (a2-1)) are preferable in that the reaction is presumed to proceed easily at .

Another embodiment of the aromatic ring-containing compound (A) in Embodiment 2 (sometimes referred to as embodiment (Y)) is a compound (a1) having a skeleton consisting of one carbon six-membered ring structure and / or two or more compounds selected from compounds (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed, and do not contribute to the structure formation of the skeleton of the compound (a1) Half of the total number of substituents and the number of substituents not contributing to the structure formation of the skeleton of the compound (a2) are —OH groups, and the other half are —H groups.

In embodiment (Y),
(i) When the aromatic ring-containing compound (A) consists of two or more compounds selected from compounds (a1) having a skeleton consisting of one carbon six-membered ring structure,
(ii) when the aromatic ring-containing compound (A) consists of two or more compounds selected from compounds (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed,
(iii) the aromatic ring-containing compound (A) is one or more selected from compounds (a1) having a skeleton consisting of one carbon six-membered ring structure and two or more carbon six-membered ring structures are bonded and/or When it consists of one or more selected from compounds (a2) having a condensed skeleton,
Any one of the three cases can be adopted.

In Embodiment (Y), "the sum of the number of substituents that do not contribute to the formation of the skeleton structure of compound (a1) and the number of substituents that do not contribute to the formation of the skeleton structure of compound (a2)" , has the following meaning. That is, in the case of (i) above, the number of substituents that do not contribute to the structure formation of the “skeleton consisting of one carbon six-membered ring structure” in each of the two or more compounds (a1) is means the total number. In the case of (ii) above, the substitution that does not contribute to the structure formation of the "skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed" in each of the two or more compounds (a2) It means the total number of groups. In the case of (iii) above, the number of substituents that do not contribute to the structure formation of the “skeleton consisting of one carbon six-membered ring structure” in each of the one or more compounds (a1), and one The number of substituents that do not contribute to the structure formation of the skeleton of the "skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed" in each of the above compounds (a2) was totaled. means number.

In embodiment (Y), for example, in the case of (i) above, when two or more compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-6), chemical formula (a1 Substituents that do not contribute to the structure formation of the skeleton consisting of one carbon six-membered ring structure of the compound represented by -5) are two —OH groups and four —H groups, and have the chemical formula (a1 Substituents that do not contribute to the structure formation of the skeleton consisting of one carbon 6-membered ring structure of the compound represented by -6) are 4 -OH groups and 2 -H groups, and the total are 6 —OH groups and 6 —H groups. Further, for example, in the case of (iii) above, one or more compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-7), and one or more compounds (a2) are represented by the following When represented by the chemical formula (a2-3), the substituents that do not contribute to the structure formation of the skeleton consisting of one carbon six-membered ring structure of the compound represented by the chemical formula (a1-5) are two —OH group and four —H groups, which do not contribute to the structure formation of the skeleton consisting of one carbon six-membered ring structure of the compound represented by the chemical formula (a1-7) are six —OH groups, which do not contribute to the structure formation of the skeleton in which two or more six-membered carbon ring structures of the compound represented by the chemical formula (a2-3) are bonded and/or condensed, are two -OH group and 6 -H groups.

By using such an aromatic ring-containing compound as the aromatic ring-containing compound (A), a reaction due to its own dehydration reaction occurs without the need for a reaction catalyst. It is possible to suppress fatal impurities existing in the material and obtain a higher quality carbon material. Moreover, by using such an aromatic ring-containing compound, a carbon material can be obtained without using a combustible gas. Also, such compounds (A) may have high reactivity that does not require catalysis.

<Representative Embodiment of Aromatic Ring-Containing Compound (A) (Embodiment 3)>
A representative embodiment (Embodiment 3) of the aromatic ring-containing compound (A) is a form in which both Embodiment 1 and Embodiment 2 are employed at the same time. That is, Embodiment 3 is an aromatic ring-containing compound that decomposes by heating to generate radicals on the aromatic ring, and one neutral molecule is formed and eliminated from two or more groups by a condensation reaction. It is an aromatic ring-containing compound. Such aromatic ring-containing compounds can cause a condensation reaction between the same molecules and/or between different molecules to become a carbon material.

Specific structures of Embodiment 3 include, for example, compound (a3-1). When compound (a3-1) is heated, carbon dioxide molecules are eliminated, radicals (reaction active sites) are generated on the aromatic rings, and hydroxyl groups and hydrogen groups are dehydrated intermolecularly, causing a condensation reaction.

By using such an aromatic ring-containing compound, a reaction due to its own dehydration reaction occurs without the need for a reaction catalyst, so that chemical reaction by-products and reaction catalysts are present in the carbon material. Fatal impurities can be suppressed, and a higher quality carbon material can be obtained. Moreover, by using such an aromatic ring-containing compound, a carbon material can be obtained without using a combustible gas. Also, such compounds (A) may have high reactivity that does not require catalysis.

≪Carbon material≫
The carbon material of the present invention shows G band, D band and G' band by Raman analysis, shows no peak derived from graphite by XRD analysis, The content ratio is 99.9% or more, and according to XRF analysis, the content ratio of nitrogen, sulfur, phosphorus, and metals other than alkali metals is 100 ppm or less.

The carbon material of the present invention can be produced by any suitable method as long as the effects of the present invention are not impaired. Such a production method preferably includes the production method of the present invention described above.

The carbon material of the present invention is a novel carbon material different from conventionally known carbon materials. Conventionally known carbon materials include, for example, carbon nanotubes, fullerenes, graphite, graphene, graphene oxide, reduced graphene oxide, artificial graphite, and carbon black.

The carbon material of the present invention typically has a honeycomb structure (graphene structure) derived from benzene rings in its structure. The presence or absence of a graphene structure can be confirmed by Raman spectroscopic analysis described later (see, for example, Non-Patent Document 3).

The carbon material of the present invention shows G band, D band and G' band by Raman analysis. That is, in the Raman spectrum obtained by Raman spectroscopic analysis, the carbon material of the present invention has a G band (generally within the range of 1550 cm ^-1 to 1650 cm ^-1 ), a D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) and the G′ band (generally within the range of 2650 cm ⁻¹ to 2750 cm ⁻¹ ). Showing such a peak in a Raman spectrum obtained by Raman spectroscopic analysis means that the carbon material of the present invention has a graphene structure or a structure similar to a graphene structure, a structure derived from defects in the graphene structure, or It means having a structure similar to a structure derived from defects in the graphene structure and containing a functional group.

If the G band is generally high in intensity and sharp, it can be said to have a cleaner graphene structure or a graphene-like structure.

The D band can generally be said to have a cleaner or graphene-like structure if the intensity is low. In addition, the fact that the D band can be confirmed means that it has a functional group, a structure derived from defects in the graphene structure, or a structure similar to a structure derived from defects in the graphene structure. . As a result, properties different from those of ordinary graphene can be exhibited.

The intensity of the G' band is generally the strongest when the graphene structure is one layer, and gradually decreases as the number of layers of the graphene structure increases. However, the peak of the G' band can be observed even if the intensity gradually decreases as the number of layers of the graphene structure increases. Therefore, having a peak in the G' band can be said to have a graphene structure or a structure similar to the graphene structure. The G' band is sometimes called the 2D band.

By Raman analysis, the carbon material of the present invention preferably has a D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) and/or a 2D' band (generally in the range of 3100 cm ^-1 to 3300 cm ^-1 ). within range). Showing such a peak in a Raman spectrum obtained by Raman spectroscopic analysis means that the carbon material of the present invention has a graphene structure or a structure similar to a graphene structure, a structure derived from defects in the graphene structure, or It means more that it has a structure similar to that derived from defects in the graphene structure and that it contains a functional group.

The D+D' and 2D' bands can generally be said to have a cleaner or graphene-like structure if the intensity is low. The D+D' band is sometimes called the D+G band. In addition, the fact that the D + D ′ band and / or 2D ′ band can be confirmed means that it has a functional group, a structure derived from defects in the graphene structure, or a structure similar to a structure derived from defects in the graphene structure. means that As a result, properties different from those of ordinary graphene can be exhibited.

The carbon material of the present invention does not show graphite-derived peaks by XRD analysis. The peak derived from graphite in the present invention means that the peak derived from the (002) plane in XRD is 26.3 degrees or higher. Carbon materials that do not have a graphite peak often have a broad peak at 26.3 degrees or lower. This indicates that the distance between carbon material layers is wider than that of graphite and that the material is different from graphite. For example, graphite nanoplates (GNPs), which are thin graphites similar to graphene, show graphite-derived peaks by XRD analysis. The fact that the carbon material of the present invention does not show graphite-derived peaks in XRD analysis means that the carbon material is different from graphite nanoplates (GNP).

The carbon material of the present invention does not substantially contain elements other than carbon and oxygen. Specifically, according to XPS analysis, the carbon material of the present invention has a total content of carbon and oxygen of 99.9% or more, preferably 99.95% or more, more preferably It is 99.99% or more, more preferably 99.995% or more, particularly preferably 99.999% or more, and most preferably substantially 100%. In the carbon material of the present invention, the total content of carbon and oxygen in all elements measured by XPS analysis is within the above range, the purity of the carbon material of the present invention is very high, and physical properties are hindered. It means that it does not contain any impurities. Further, "substantially 100%" means that peaks other than carbon and oxygen are not detected in the XPS analysis (cannot be distinguished from the baseline).

According to XRF analysis, the carbon material of the present invention has a content ratio of nitrogen, sulfur, phosphorus, and metals other than alkali metals, each of which is 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less. , more preferably 5 ppm or less, particularly preferably 1 ppm or less, and most preferably substantially 0 ppm. The content ratio of nitrogen, sulfur, phosphorus, and metals other than alkali metals measured by XRF analysis in the carbon material of the present invention is within the above range because the carbon material of the present invention contains nitrogen and sulfur This means that the carbon material has a very low (extremely high purity) content of impurities such as phosphorus and metals other than alkali metals.

The carbon material of the present invention can exist in a bulk state. The description of the bulk state is as described above, and representative examples are particles, pellets, films, and the like. Examples of the state of existence of particles include powder. The film is preferably a self-supporting film.

The carbon material of the present invention is a novel carbon material having the characteristics described above. That is, the carbon material of the present invention has the same or similar crystal structure as graphene, and has substantially the same structure as reduced graphene oxide in that it is a substantially monolayer oxygen-containing carbon material, However, unlike reduced graphene oxide in that it does not substantially contain elements other than carbon and oxygen, and also differs from graphite in terms of crystal structure, the content of metals other than nitrogen, sulfur, phosphorus, and alkali metals is low. It is a novel carbon material that has a very low fraction (ie, very high purity) and can exist in bulk.

The carbon material of the present invention has a structure derived from defects in the graphene structure or a structure similar to a structure derived from defects in the graphene structure. Due to the presence of such defects, the carbon material of the present invention can contribute to the development of solubility and dispersibility in solvents and resins.

<<Carbon material composition>>
The carbon material composition of the present invention contains the carbon material of the present invention. Since the carbon material of the present invention has a structure derived from defects in the graphene structure or a structure similar to a structure derived from defects in the graphene structure, it can exhibit solubility and dispersibility in solvents and resins. . Therefore, when the carbon material of the present invention and a solvent are blended, a dispersion or solution in the solvent can be obtained. It is possible to obtain objects and develop applications in various fields.

The content ratio of the carbon material of the present invention in the carbon material composition of the present invention can be appropriately set according to the purpose. Such a content ratio is typically preferably 0.01% by weight to 99.9% by weight.

One embodiment of the carbon material composition of the present invention contains a solvent. In one preferred embodiment of the carbon material composition of the present invention, the carbon material is dispersed in the solvent.

One embodiment of the carbon material composition of the present invention contains a resin. In one preferred embodiment of the carbon material composition of the present invention, the carbon material is dispersed in the resin.

Examples of solvents that can be contained in the carbon material composition of the present invention include amide solvents such as NMP (N-methylpyrrolidone) and DMF (N,N-dimethylformamide), ketone solvents such as acetone, and 2-propanol. alcohol solvents such as Only one kind of such solvent may be used, or two or more kinds thereof may be used.

Examples of resins that can be contained in the carbon material composition of the present invention include rubber-based resins such as SBR, general-purpose epoxy resins, phenolic resins, polyimides, and polyamide resins. Only one kind of such resin may be used, or two or more kinds thereof may be used.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. "Parts" means "parts by weight" and "%" means "% by weight" unless otherwise specified. Also, in this specification, "weight" may be read as "mass".

<Raman spectroscopic analysis>
Raman spectroscopic analysis was performed using the following equipment and conditions.
Measuring device: Microscopic Raman (JASCO NRS-3100)
Measurement conditions: Use of 532 nm laser, 20x objective lens, CCD capture time of 1 second, integration 64 times (resolution = 4 cm-1)

<XRD analysis>
The XRD measurement was performed under the following conditions using a fully automatic horizontal X-ray diffractometer (SMART LAB manufactured by Rigaku Corporation).
CuKα1 line: 0.15406 nm
Scan range: 10°-90°
X-ray output setting: 45kV-200mA
Step size: 0.020°
Scanning speed: 0.5°min ^-1 -4°min ^-1
The XRD measurement was performed in a state in which an inert atmosphere was maintained by loading the sample onto an airtight sample table in a glove box.

<XRF analysis>
The XRF measurement was performed by a calibration curve method using a fluorescent X-ray analyzer (manufactured by Philips, PW2404). Those with an element concentration of 0.01% or more were read as each component. Since hydrogen was not detected, the total amount of elements other than hydrogen was calculated as 100%.

<XPS analysis>
XPS measurements were performed using a photoelectron spectrometer (JPS-9000MX, manufactured by JEOL Ltd.). Since hydrogen was not detected, the total amount of elements other than hydrogen was calculated as 100%.

[Example 1]
Phloroglucinol manufactured by Tokyo Chemical Industry Co., Ltd. was calcined at 1300° C. for 1 hour in a nitrogen atmosphere using SUPER BOY manufactured by Marusho Denki Co., Ltd. The results of Raman analysis of the obtained carbon material are shown in FIG. 1, and the results of XRD analysis are shown in FIG. In addition, XPS analysis showed substantially only carbon and oxygen elements, and XRF analysis showed that elements other than oxygen and carbon were 100 ppm or less.

[Comparative Example 1]
Graphene oxide was prepared with reference to Patent Document WO2017/082262. After adjusting the obtained graphene oxide to a concentration of 0.2% by weight with water, 5 equivalents of L-ascorbic acid manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. was added to the graphene oxide and reacted at 70° C. for 2 hours. . After the reaction, the reaction solution was purified by repeatedly washing with water and filtering, and then washed with acetone and filtered. The obtained wet cake was vacuum-dried to obtain reduced graphene oxide. FIG. 3 shows the Raman analysis results of the obtained carbon material (reduced graphene oxide), and FIG. 4 shows the XRD analysis results thereof. Further, XRF analysis showed 321 ppm of sulfur and 207 ppm of manganese.

[Comparative Example 2]
FIG. 5 shows the XRD analysis results of exfoliated graphene (Graphene nanoplatelets aggregates) manufactured by STREM. It can be seen that the exfoliated graphene (GNP) has a strong graphite peak and cannot be said to be graphene.

The carbon material obtained by the production method of the present invention, the carbon material of the present invention, and the carbon material composition of the present invention can be used as novel functional materials in various fields due to their characteristic physical properties.

Claims (13)

A method for producing a carbon material,
calcining an aromatic ring-containing compound (A) composed of carbon, hydrogen, and oxygen and having a molecular weight of 500 or less at a temperature of 700° C. or higher ;
The aromatic ring-containing compound (A) is a compound in which one neutral molecule is formed and eliminated from two or more groups by a condensation reaction,
The condensation reaction is
(a) a condensation reaction by the formation and elimination of H ₂ O from —H and —OH groups ;
(b) a condensation reaction by the formation and elimination of ROH from a -H group and a -OR group (where R is any suitable substituted or unsubstituted alkyl group);
(c) condensation reaction by formation and elimination of RCOOH from -H group and -OOCR group (R is any suitable substituted or unsubstituted alkyl group);
is either
A method for producing a carbon material that can be produced in bulk . The method for producing a carbon material according to claim 1, wherein the aromatic ring-containing compound (A) has a condensation reaction temperature of 400°C or lower. TG-DTA analysis of the aromatic ring-containing compound (A) under a nitrogen gas atmosphere from 40 ° C. under the condition of temperature increase of 10 ° C./min. 3. The method for producing a carbon material according to claim 1, wherein the weight ratio of weight M500 (M500/M50) is 0.2 or more. 4. The method for producing a carbon material according to any one of claims 1 to 3, wherein the aromatic ring-containing compound (A) is an aromatic compound having a hydroxyl group. The method for producing a carbon material according to any one of claims 1 to 4, wherein the firing temperature is 1000°C to 1500°C. The method for producing a carbon material according to any one of claims 1 to 5, wherein the aromatic ring-containing compound (A) is phloroglucinol or hexahydroxytriphenylene . A carbon material,
Raman analysis shows G-band, D-band and G'-band,
XRD analysis shows no peaks derived from graphite,
XPS analysis shows that the total content of carbon and oxygen in all elements is 99.9% or more,
According to XRF analysis, the percentage content of nitrogen, sulfur, phosphorus, and metals other than alkali metals is each 100 ppm or less.
A carbon material that can exist in a bulk state . 8. The carbon material according to claim 7, which exhibits a D+D' band and/or a 2D' band by Raman analysis. A carbon material composition comprising the carbon material according to claim 7 or 8 . 10. The carbon material composition according to claim 9 , comprising a solvent. 11. The carbon material composition according to claim 10 , wherein said carbon material is dispersed in said solvent. The carbon material composition according to claim 9 or 10 , containing a resin. 13. The carbon material composition according to claim 12 , wherein the carbon material is dispersed in the resin.

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