JP7127980B2 - Carbon material and liquid containing carbon material - Google Patents

Description

The present invention relates to carbon materials. The present invention also relates to a carbon material-containing liquid.

In recent years, carbon materials such as carbon nanotubes, fullerenes, graphite films, graphene, graphene oxide, reduced-type graphene oxide, artificial graphite, and carbon black have found new functionalities in various fields due to their characteristic physical properties. It is expected as a material (for example, Non-Patent Documents 1-3).

However, conventional carbon materials, especially carbon nanotubes and graphene, which have been attracting attention in recent years as nanocarbon materials, have the problem of extremely poor solubility in solvents, and good handling properties have not been achieved. . Fullerene is the only soluble material among carbon materials, but fullerene C60 has a diameter of about 1 nm. It is a low-molecular compound rather than a nanocarbon material, and does not exhibit the physical properties required for carbon materials. .

Further, conventional carbon materials, particularly carbon nanotubes and graphene, which have been attracting attention as nanocarbon materials in recent years, are synthesized using metal-based catalysts in their production. These metal components can be removed to some extent in the subsequent refining process, but it is practically impossible to eliminate them. In addition, there are many materials in which the metal component taken into the carbon material cannot be removed, and many impurity metal components remain in the carbon material.

In order to improve the handleability of carbon materials, the introduction of soluble modifying groups into carbon materials has been studied (Patent Document 1). However, although the dispersibility of the carbon material is somewhat improved by the introduction of the soluble modifying group, there is still a problem that the solubility in the solvent is extremely poor. There is also the problem that these modifying groups essentially act as impurities on the carbon material.

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

Japanese Patent No. 3764986

An object of the present invention is to provide a novel carbon material that is more soluble in a solvent than conventional carbon materials, can be easily handled, and contains substantially no metal components that become impurities. That's what it is. Another object of the present invention is to provide a carbon material-containing liquid obtained by dissolving at least part of such a carbon material in a solvent.

The carbon material of the present invention is
Having peaks in the G band (within the range of 1550 cm ^-1 to 1650 cm ^-1 ) and the G' band (within the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum chart obtained by Raman spectroscopic analysis,
Contains carbon-based compounds that are soluble in solvents.

In one embodiment, the carbon material has a peak in the D band (within the range of 1300 cm ⁻¹ to 1400 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis.

In one embodiment, the carbon material has a peak in the D+D' band (within the range of 2800 cm ⁻¹ to 3000 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis.

In one embodiment, the XRD spectrum chart obtained by XRD analysis of the carbon-based compound has a peak within the range of 20° to 30°.

In one embodiment, the carbon material is obtained by heating a compound (A) in which a condensation reaction occurs between identical molecules and/or between different molecules upon heating.

In one embodiment, the compound (A) is solid and has a melting point at 23°C.

In one embodiment, the heating temperature is (T±50)°C, where T°C is the decomposition temperature of the compound (A).

In one embodiment, the carbon material can be synthesized or exist in bulk.

The carbon material-containing liquid of the present invention is obtained by dissolving at least part of the carbon material in a solvent.

ADVANTAGE OF THE INVENTION According to the present invention, there is provided a novel carbon material that is more soluble in a solvent than conventional carbon materials, can be easily handled, and contains substantially no metal components as impurities. be able to. Also, a carbon material-containing liquid can be provided in which at least part of such a carbon material is dissolved in a solvent.

1 is a Raman spectrum diagram of carbon material (1). FIG. 1 is an XRD spectrum diagram of carbon material (1). FIG. It is a Raman spectrum diagram of carbon material (2). FIG. 3 is an XRD spectrum diagram of carbon material (2). It is a Raman spectrum diagram of a carbon material (C1). It is an XRD spectrum diagram of a carbon material (C1). It is a Raman spectrum diagram of carbon material (3). FIG. 3 is an XRD spectrum diagram of carbon material (3). It is a Raman spectrum diagram of carbon material (4). FIG. 4 is an XRD spectrum diagram of carbon material (4). It is a Raman spectrum diagram of carbon material (5). FIG. 4 is an XRD spectrum diagram of carbon material (5). It is a Raman spectrum diagram of a carbon material (C2). It is an XRD spectrum figure of a carbon material (C2).

≪Carbon material≫
The carbon material of the present invention is a novel carbon material different from conventionally known carbon materials. Examples of conventionally known carbon materials include carbon nanotubes, fullerenes, graphite films, graphene, graphene oxide, reduced graphene oxide, artificial graphite, and carbon black.

A carbon material in this specification means a material having 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 is superior to conventional carbon materials in terms of solubility in solvents and can achieve good handleability.

In the carbon material of the present invention, the total content of metal components as impurities is usually preferably 0.1% by mass or less, more preferably 0.01% by mass or less, relative to 100% by mass of the carbon material. Yes, particularly preferably substantially zero. These metal components can be confirmed by X-ray fluorescence elemental analysis (XRF).

The carbon material of the present invention is a carbon material whose constituent elements are preferably composed of elements selected from carbon, oxygen, hydrogen, nitrogen, sulfur, fluorine, chlorine, bromine and iodine, and more preferably carbon , oxygen, hydrogen, nitrogen, and sulfur, more preferably a carbon material composed of an element selected from carbon, oxygen, hydrogen, and nitrogen, particularly preferably carbon, It is a carbon material composed of an element selected from oxygen and hydrogen. When the total amount of elements other than hydrogen among the elements constituting the carbon material of the present invention is 100 atomic %, carbon is preferably 60 atomic % or more, more preferably 70 atomic % or more, and further preferably It is 75 atomic % or more. Moreover, elements other than carbon are preferably 10 atomic % or more. When the ratio of each element falls within this range, it is possible to exhibit good solubility even though it is a carbon material. These constituent element ratios can be quantified by X-ray photoelectron spectroscopy (XPS).

The carbon material of the present invention can preferably adopt the following embodiments with respect to the solvent.
(Embodiment 1) An embodiment in which all of the carbon material is dissolved in the solvent. That is, an embodiment in which the carbon material consists of a component (component A) that dissolves in a solvent.
(Embodiment 2) An embodiment in which a part of the carbon material is dissolved in the solvent. That is, an embodiment in which the carbon material consists of a solvent-soluble component (component A) and a solvent-insoluble component (component B). In this case, component B includes, for example, a component that disperses in the solvent (component B1) and a component that precipitates in the solvent (component B2).

Examples of solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, Examples include dichloromethane and the like, preferably N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide and chloroform, more preferably N,N-dimethylformamide and N-methylpyrrolidone. be.

That the carbon material of the present invention contains a carbon-based compound that is soluble in a solvent means that it contains a carbon-based compound that is soluble in at least one of the above solvents. As a soluble solvent, any of the above solvents may be used, but at least one of N,N-dimethylformamide and N-methylpyrrolidone is preferred.

As a method for determining whether it is soluble in a solvent, for example, after mixing the carbon material so as to be 0.001% by mass with respect to the solvent, ultrasonic treatment is performed for 1 hour, and the obtained liquid is passed through a PTFE filter paper (pore size 0.45 μm), it can be determined whether or not the liquid that has passed through the filter paper contains a carbon-based compound. If the liquid that has passed through the filter paper contains a carbon-based compound, it is determined that the carbon material contains a carbon-based compound that is soluble in the solvent. As the PTFE filter paper, for example, GL Chromatodisc (model 13P) manufactured by GL Sciences Co., Ltd. can be used.

The carbon material of the present invention has (i) a G band (within the range of 1550 cm ^-1 to 1650 cm ^-1 ) and a G' band (within the range of 2650 cm ^-1 to 2750 cm ^-1 ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. and (ii) contain a carbon-based compound that is soluble in the solvent.

A carbon material having a graphene structure shows a peak in the G band (within the range of 1550 cm ⁻¹ to 1650 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. Therefore, the fact that the carbon material of the present invention has a peak in the G band (within the range of 1550 cm ⁻¹ to 1650 cm ⁻¹ ) in the Raman spectrum chart obtained by Raman spectroscopic analysis means that the carbon material of the present invention has a graphene structure or graphene It means having a similar structure to the structure. If the G band is high in intensity and sharp, it can be said to have a finer graphene structure or a graphene-like structure.

A carbon material having a graphene structure exhibits a peak in the G' band (within the range of 2650 cm ^-1 to 2750 cm ^-1 ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. Therefore, the fact that the carbon material of the present invention has a peak in the G′ band (within the range of 2650 cm ⁻¹ to 2750 cm ⁻¹ ) in the Raman spectrum chart obtained by Raman spectroscopic analysis means that the carbon material of the present invention has a graphene structure or It means that it has a structure similar to the graphene structure. The intensity of the G' band is 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 means that the carbon material of the present invention has a graphene structure or a graphene-like structure. The G' band is sometimes called the 2D band.

The molecular weight of the carbon-based compound contained in the carbon material of the present invention is preferably 1,000 to 1,300,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 700,000, and particularly preferably 15,000 to 500,000, Most preferably 20,000 to 300,000. If the molecular weight of the carbon-based compound contained in the carbon material of the present invention is within the above range, combined with the feature (i) of the carbon material of the present invention, the solubility in a solvent is superior to that of conventional carbon materials. , it can be a novel carbon material that can realize good handleability. If the molecular weight of the carbon-based compound contained in the carbon material of the present invention exceeds 1,300,000, the solubility of the carbon material of the present invention in solvents may deteriorate. If the molecular weight of the carbon-based compound contained in the carbon material of the present invention is less than 1,000, the characteristics of the carbon material may be weakened. These molecular weights can be analyzed by the method described later.

The content of the carbon-based compound in the carbon material of the present invention is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and still more preferably 90% by mass to 100% by mass. , particularly preferably 95% by mass to 100% by mass, most preferably substantially 100% by mass. If the content ratio of the carbon-based compound in the carbon material of the present invention is within the above range, the carbon material of the present invention, combined with the above characteristics (i) and (ii) of the carbon material of the present invention, is a conventional carbon It can be a novel carbon material that has better solubility in a solvent than other materials and can realize good handleability.

The carbon material of the present invention preferably has a peak in the D band (within the range of 1300 cm ⁻¹ to 1400 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. A carbon material having a structure derived from defects in the graphene structure shows a peak in the D band (within the range of 1300 cm ⁻¹ to 1400 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. Therefore, the carbon material having a peak in the D band (within the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum chart obtained by Raman spectroscopic analysis means that the carbon material has a structure derived from defects in the graphene structure or It means that it has a structure similar to the structure derived from defects in the graphene structure. If the D band is less intense, it can be said to have a cleaner graphene structure or a graphene-like structure.

The carbon material of the present invention preferably has a peak in the D+D' band (within the range of 2800 cm ⁻¹ to 3000 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. A carbon material having a structure derived from defects in the graphene structure shows a peak in the D+D' band (within the range of 2800 cm ⁻¹ to 3000 cm ⁻¹ ) in a Raman spectrum chart obtained by Raman spectroscopic analysis. Therefore, the fact that the carbon material of the present invention has a peak in the D+D′ band (within the range of 2800 cm ⁻¹ to 3000 cm ⁻¹ ) in the Raman spectrum chart obtained by Raman spectroscopic analysis means that the carbon material has defects in the graphene structure. It means having a structure similar to the structure derived from or derived from defects in the graphene structure. If the D+D' band is less intense, it can be said to have a cleaner graphene structure or a graphene-like structure. The D+D' band is sometimes called the D+G band.

When the carbon material of the present invention has defects in part of the graphene structure, these defects may contribute to the solubility of the carbon material of the present invention in solvents.

As described above, the carbon material of the present invention is a novel carbon material different from conventionally known carbon materials, has a graphene structure or a structure similar to a graphene structure, and is more resistant to solvents than conventional carbon materials. It is excellent in solubility and can realize good handleability.

The carbon material of the present invention preferably exhibits a peak within the range of 20° to 30° in an XRD spectrum chart obtained by XRD analysis. That is, it is also one of preferred embodiments that the carbon material of the present invention has a structure in which graphene structures are laminated (graphene laminated structure). By having a laminated structure, the carbon material of the present invention can become stronger and more stable.

In the carbon material of the present invention, preferably at least part of the carbon-based compound is soluble in the solvent. Since at least part of the carbon-based compound is soluble in the solvent, the carbon material of the present invention can achieve better handleability.

The carbon material of the present invention is preferably synthesized or can exist in bulk. In general, the properties possessed by the bulk are the inherent properties of the material. In the bulk state, the basic properties of the substance, such as the boiling point, melting point, viscosity, density, etc., can be determined.In order to express unique properties, the bulk portion can be drastically reduced to increase the interface. It is possible. 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.

The carbon material of the present invention is preferably obtained by heating a compound (A) in which a condensation reaction occurs between identical molecules and/or between different molecules upon heating. A preferred embodiment of the carbon material of the present invention synthesized in bulk is obtained by heating compound (A) in bulk.

Heating the compound (A) in a bulk state means, for example, heating particles (powder) composed of the compound (A), and molding particles (e.g., powder) composed of the compound (A) into pellets or It includes actions such as heating the formed body after forming into a film, and heating particles (for example, powder) composed of the compound (A) in a liquid. 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 compound (A) when heated.

The carbon material of the present invention can be obtained by heating particles (for example, powder) or compacts under preferable conditions. May melt and become liquid. Such a process is also included in "heating compound (A) in bulk". On the other hand, as an example that is not "heated in a bulk state" in the meaning of the present invention, for example, the compound (A) is dissolved in a solvent and applied to an arbitrary substrate to form a film, and the substrate is Examples include a method of forming a thin film by heating, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, 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.

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. By adopting such a compound (A), it is possible to provide a novel carbon material that is superior in solubility in solvents to conventional carbon materials and that can achieve better handleability.

When the carbon material of the present invention is obtained by heating the compound (A) in which a condensation reaction occurs between the same molecules and/or between different molecules by heating, the heating temperature is the decomposition temperature of the compound (A). °C, preferably (T±50)°C, more preferably (T±45)°C, still more preferably (T±40)°C, and particularly preferably (T±35)°C and most preferably (T±30)°C. By adjusting the heating temperature within the above range, it is possible to provide a novel carbon material that is superior to conventional carbon materials in terms of solubility in a solvent and can achieve better handleability.

Compound (A) may be a single compound or a mixture of two or more compounds. When the compound (A) is a mixture of two or more compounds, at least one compound in the mixture may have the physical properties (decomposition point, melting point, etc.), structure, etc. described in the present invention. Conditions such as heating temperature and heating time may be determined based on the compound.

<Representative Embodiment of Compound (A) (Embodiment 1)>
A representative embodiment (Embodiment 1) of compound (A) is an aromatic compound that is decomposed by heating to generate radicals on an aromatic ring. An aromatic compound in which a radical is generated on an aromatic ring causes a condensation reaction between the same molecules and/or between different molecules to become a carbon material.

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

As the aromatic compound that generates gas by heating, any appropriate aromatic compound can be adopted as long as it is an aromatic compound that generates gas by heating. At least one selected from CO, CO ₂ , N ₂ , O ₂ , H ₂ and NO 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 N ₂ upon heating include aromatic compounds having a “—NH—NH—” structure, “—N=N—” structure, and “—N ₃ ” structure (e.g., aromatic azo compounds, aromatic azide compounds, triazole-substituted aromatic compounds, tetrazole-substituted aromatic compounds, triazine or derivatives thereof, tetrazine or derivatives thereof, aromatic hydrazine derivatives, etc.).

Examples of aromatic compounds that generate _N2 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.

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.

Examples of aromatic compounds that generate NO ₂ upon heating include aromatic compounds having a “—NO ₂ ” structure (eg, aromatic nitro compounds, etc.).

Examples of aromatic compounds that generate NO ₂ upon heating include the following compounds.

Aromatic compounds that are decomposed by heating to generate radicals on the aromatic ring have decomposability by heating, and at least a part of the skeleton is separated and decomposed into gas molecules (preferably CO, CO ₂ , At least one selected from N ₂ , O ₂ , H ₂ and NO ₂ ) is produced, and a radical is produced on the remaining aromatic ring. By using such an aromatic compound, a reaction occurs only by decomposition of itself without the need for a reaction catalyst. Impurities can be suppressed, and a higher quality carbon material can be obtained. Moreover, by using such an aromatic compound, a carbon material can be obtained in a relatively mild temperature environment without using combustible gas. Also, such aromatic compounds may have high reactivity that does not require catalysis.

<Representative Embodiment of Compound (A) (Embodiment 2)>
A representative embodiment (embodiment 2) of compound (A) is a compound in which a 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 a 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 eliminated, within a range that 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 HX from -H group and -X group (where X is halogen or CN);
₍ d) a condensation reaction with the formation and elimination of NH from the —H and _—NH2 groups;
(e) a condensation reaction by the formation and elimination of _RNH2 from a -H group and a -NHR group (where R is any suitable substituted or unsubstituted alkyl group);
(f) condensation reaction by formation and elimination of R ¹ R ² NH from —H group and —NR ¹ R ² group (R ¹ and R ² are any suitable substituted or unsubstituted alkyl groups); ,
(g) a condensation reaction with the formation and elimination of H ₂ S from —H and —SH groups;
(h) a condensation reaction by formation and elimination of RSH from a -H group and a -SR group (where R is any suitable substituted or unsubstituted alkyl group);
(i) condensation reaction by formation and elimination of RCOOH from -H group and -OOCR group (R is any suitable substituted or unsubstituted alkyl group);
(j) a condensation reaction with the formation and elimination of H ₂ SO ₃ from —H and —OSO(OH) groups;
(k) condensation reaction by formation and elimination of RSO ₂ (OH) from —H group and —OSO ₂ R group, where R is any suitable substituted or unsubstituted alkyl group;
(l) condensation reaction by formation and elimination of ROSO ₃ H from —H group and —OSO ₂ (OR) group (R is any suitable substituted or unsubstituted alkyl group);
(m) a condensation reaction with the formation and elimination of H ₂ SO ₄ from —H and —OSO ₂ (OH) groups;
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 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 or more carbon A compound (a2) having a skeleton to which a 6-membered ring structure is bonded and/or condensed, half of the substituents not contributing to the structure formation of the skeleton are —OH groups, and the other half are —H is the base.

In embodiment (X),
(i) when the compound (A) is a compound (a1) having a skeleton consisting of one carbon six-membered ring structure,
(ii) when the 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, compound (A) can effectively undergo dehydration reaction between identical molecules and/or different molecules by heating.

The compound (A) that can be employed in the 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 condensed If it is a compound (a2) having a skeletal structure, half of the number of substituents that do not contribute to the structure formation of the skeletal structure are —OH groups, and the other half are —H groups, the compound of the present invention Any appropriate compound can be employed as long as it does not impair the effect. Examples of such compound (A) include the following compounds.

Among the 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, and the reaction occurs at a low temperature. Phloroglucinol (compound (a1-2)) and hexahydroxytriphenylene (HHTP) (compound (a2-1)) are preferred because they are presumed to progress easily.

Another embodiment of compound (A) in embodiment 2 (sometimes referred to as embodiment (Y)) is compound (a1) and/or 2 having a skeleton consisting of one carbon six-membered ring structure two or more selected from compounds (a2) having a skeleton in which at least one carbon 6-membered ring structure is bonded and/or condensed, and substituents that do not contribute to the structure formation of the skeleton of the compound (a1) Half of the total number and the number of substituents that do not contribute 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 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 compound (A) consists of two or more compounds selected from compound (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed,
(iii) Compound (A) has a skeleton consisting of one carbon 6-membered ring structure, and at least one selected from compound (a1) and two or more carbon 6-membered ring structures are bonded and/or condensed. When it consists of one or more selected from compounds (a2) having a 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 6-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 a compound (A), a reaction due to its own dehydration reaction occurs without the need for a reaction catalyst. Fatal impurities can be suppressed, and a higher quality carbon material can be obtained. Moreover, by using such a compound (A), a carbon material can be obtained in a relatively mild temperature environment without using a combustible gas. Also, such compounds (A) may have high reactivity that does not require catalysis.

<Representative Embodiment of Compound (A) (Embodiment 3)>
A representative embodiment (Embodiment 3) of compound (A) is a form in which both Embodiment 1 and Embodiment 2 are employed simultaneously. That is, Embodiment 3 is an aromatic compound that is decomposed by heating to generate radicals on an aromatic ring, and that one neutral molecule is formed and eliminated from two or more groups by a condensation reaction. is a compound. Such a compound (A) can cause a condensation reaction between identical molecules and/or 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 a compound (A), a reaction due to its own dehydration reaction occurs without the need for a reaction catalyst. Fatal impurities can be suppressed, and a higher quality carbon material can be obtained. Moreover, by using such a compound (A), a carbon material can be obtained in a relatively mild temperature environment without using a combustible gas. Also, such compounds (A) may have high reactivity that does not require catalysis.

<<Liquid containing carbon material>>
The carbon material-containing liquid of the present invention is obtained by dissolving at least part of the carbon material of the present invention in a solvent.

The carbon material-containing liquid of the present invention may be obtained by dissolving the entire carbon material of the present invention in a solvent, or by dissolving a part of the carbon material of the present invention in a solvent. good too. When a part of the carbon material of the present invention is dissolved in a solvent, the part that is not dissolved in the solvent may be dispersed in the solvent or precipitated in the solvent.

Solvents in which the carbon material of the present invention is soluble include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methylethylketone, methylisobutylketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, dichloromethane and the like, preferably N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, chloroform, more preferably N,N - dimethylformamide, N-methylpyrrolidone. As described above, the carbon material-containing liquid of the present invention may be a solution in which all of the carbon material of the present invention is dissolved in these solvents, or a solution in which a part of the carbon material of the present invention is dissolved. There may be.

<<Manufacturing method of carbon material>>
The carbon material of the present invention can be produced by any appropriate method as long as the effects of the present invention are not impaired. Such a method includes, for example, a method of heating compound (A) in which a condensation reaction occurs between the same molecules and/or between different molecules upon heating. In this case, the heating temperature is preferably (T±50)° C., more preferably (T±45)° C., still more preferably (T ±40)°C, particularly preferably (T±35)°C, most preferably (T±30)°C. By adjusting the heating temperature within the above range, it is possible to provide a novel carbon material that is superior to conventional carbon materials in terms of solubility in a solvent and can achieve better handleability.

The details of compound (A) and heating of compound (A) are as described above.

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.

As the heating time, any suitable heating time can be adopted depending on the molecular weight or solubility 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.

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

<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)
In Raman analysis, the G' band and the D+D' band may overlap, and the D+D' band may be analyzed as a broad peak having a shoulder. In this case, the point of inflection of the shoulder peak is regarded as the peak of the G' band.

<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%.

<Judgment of solubility>
Judgment of whether it is soluble or not is performed by mixing the carbon material so as to be 0.001% by mass with respect to the solvent, performing ultrasonic treatment for 1 hour, and applying the resulting liquid to GL chromatograph manufactured by GL Sciences Co., Ltd. A carbon material is said to be soluble in a solvent if it passes through the filter paper when passed through a disc (model 13P, 0.45 μm pore size).

<Measurement of molecular weight>
The molecular weight is measured using gel permeation chromatography (GPC, HLC-8220GPC manufactured by Tosoh Corporation), N,N-dimethylformamide (containing 0.1% LiBr) so that each carbon material is 0.02% by mass. After sonication for 1 hour, it was passed through a PTFE filter paper (0.45 μm) for pretreatment, and the filtrate was N,N-dimethylformamide (containing 0.1% LiBr) as a developing solvent. The molecular weight was calculated in terms of polystyrene. The maximum molecular weight in the carbon material was calculated from the rising point of the peak.

<Confirmation of solubility/dispersibility>
Each of the obtained carbon materials was added to a solvent and subjected to ultrasonic treatment for 1 hour. The liquid after ultrasonic treatment is passed through a PTFE filter paper (pore size 0.45 μm), and when no solid remains on the filter paper, it is completely dissolved. Partial dissolution, solid remaining on the filter paper, and no carbonaceous material in the filtrate were judged to be insoluble. The presence of a carbon material in the filtrate can be determined by the fact that the filtrate has a peak in the above-described GPC analysis and that the non-volatile matter in the filtrate has a peak derived from the carbon material in the above-described Raman spectroscopic analysis.
To confirm the dispersibility, the solid remaining on the filter paper was added to the solvent, the ultrasonic treatment was performed again for 1 hour, and the resulting liquid was allowed to stand for 10 minutes. , Partially sedimented was judged to be partially dispersed, and completely sedimented was judged to be non-dispersed.
These dissolved portion, dispersed portion, and sedimented portion can be separated by operations such as filtration and centrifugation, and can be applied to applications that take advantage of their respective characteristics.

[Example 1]
Phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 220 ° C., decomposition point: 330 ° C., 1 g) was placed on a quartz boat (volume: 5 ml), and an annular furnace (manufactured by Toyo Thermo Systems Co., Ltd., KTF045N1, furnace tube: It was fired at 300° C. for 3 hours under a nitrogen stream using quartz (φ50 mm×1 m). After firing, 500 mg of a black solid (carbon material (1)) was obtained. When the solubility and solubility/dispersibility of this carbon material (1) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was soluble and completely dissolved. Further, when the molecular weight was measured, the weight average molecular weight was 39,000 and the maximum molecular weight was 320,000.
The Raman spectrum of the obtained carbon material (1) is shown in FIG. 1, and the XRD spectrum is shown in FIG. Since the Raman spectrum has peaks at 1375 cm ⁻¹ , 1600 cm ⁻¹ , 2700 cm ⁻¹ and 2890 cm ⁻¹ and the XRD spectrum has a 25.0° peak, the carbon material (1) has a graphene structure and graphene It was found to be a carbon material containing a carbon-based compound having a laminated structure. The ratio of elements other than hydrogen among the elements constituting the carbon material (1) was 76.77% for carbon and 23.23% for oxygen. No contained metal component was detected (less than 0.01%).

[Example 2]
450 mg of a black solid (carbon material (2)) was obtained in the same manner as in Example 1, except that the firing temperature was 350° C. and the firing time was 1 hour. When the solubility and solubility/dispersibility of this carbon material (2) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was soluble, partially dissolved and partially dispersed. . Further, when the molecular weight of the soluble portion was measured, it was found to have a weight average molecular weight of 120,000 and a maximum molecular weight of 1,300,000.
The Raman spectrum and the XRD spectrum of the obtained carbon material (2) are shown in FIG. 3 and FIG. 4, respectively. The Raman spectrum has peaks at 1355 cm ⁻¹ , 1590 cm ⁻¹ , 2695 cm ⁻¹ and 2885 cm ⁻¹ , and the XRD spectrum has peaks at 25.1°, so the carbon material (2) has a graphene structure and It was found to be a carbon material containing a carbon-based compound having a structure in which graphene structures are laminated. The ratio of elements other than hydrogen among the elements constituting the carbon material (2) was 77.55% for carbon and 22.45% for oxygen. No contained metal component was detected (less than 0.01%).

[Comparative Example 1]
430 mg of a black solid (carbon material (C1)) was obtained in the same manner as in Example 1, except that the firing temperature was 400° C. and the firing time was 1 hour. When the solubility and solubility/dispersibility of this carbon material (C1) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was insoluble and non-dispersible.
The Raman spectrum and the XRD spectrum of the obtained carbon material (C1) are shown in FIG. 5 and FIG. 6, respectively. The Raman spectrum has peaks at 1345 cm ⁻¹ , 1590 cm ⁻¹ , 2695 cm ⁻¹ and 2880 cm ⁻¹ , and the XRD spectrum has peaks at 25.1°, so the carbon material (C1) has a graphene structure and It was found to be a carbon material containing a carbon-based compound having a structure in which graphene structures are laminated. In addition, the ratio of elements other than hydrogen among the elements constituting the carbon material (C1) was 77.95% for carbon and 22.05% for oxygen.

[Example 3]
Hexahydroxytriphenylene (HHTP) (manufactured by Wako Pure Chemical Industries, Ltd., melting point: 400 ° C., decomposition point: 430 ° C., 1 g) was placed on a quartz boat (volume: 5 ml) and an annular furnace (manufactured by Toyo Thermo Systems Co., Ltd., KTF045N1 , Furnace tube: quartz φ50 mm×1 m), and fired at 400° C. for 1 hour under nitrogen flow. After firing, 650 mg of a black solid (carbon material (3)) was obtained. When the solubility and solubility/dispersibility of this carbon material (3) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was soluble, partially soluble, and had good dispersibility. there were. Further, when the molecular weight of the soluble portion was measured, it was found to have a weight average molecular weight of 130,000 and a maximum molecular weight of 1,000,000.
The Raman spectrum and the XRD spectrum of the obtained carbon material (3) are shown in FIG. 7 and FIG. 8, respectively. The Raman spectrum has peaks at 1345 cm ⁻¹ , 1600 cm ⁻¹ , 2690 cm ⁻¹ and 2900 cm ⁻¹ , and the XRD spectrum has peaks at 25.8°, so the carbon material (3) has a graphene structure and It was found to be a carbon material containing a carbon-based compound having a structure in which graphene structures are laminated. The ratio of elements other than hydrogen among the elements constituting the carbon material (3) was 79.53% for carbon and 20.47% for oxygen. No contained metal component was detected (less than 0.01%).

[Example 4]
620 mg of a black solid (carbon material (4)) was obtained in the same manner as in Example 3 except that the firing temperature was 430° C. and the firing time was 1 hour. When the solubility and solubility/dispersibility of this carbon material (4) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was soluble, partially dissolved and partially dispersed. . Further, when the molecular weight of the soluble portion was measured, it was found to have a weight average molecular weight of 130,000 and a maximum molecular weight of 1,000,000.
The Raman spectrum and the XRD spectrum of the obtained carbon material (4) are shown in FIG. 9 and FIG. 10, respectively. The Raman spectrum has peaks at 1345 cm ⁻¹ , 1600 cm ⁻¹ , 2700 cm ⁻¹ and 2885 cm ⁻¹ , and the XRD spectrum has peaks at 26.0°, so the carbon material (4) has a graphene structure and It was found to be a carbon material containing a carbon-based compound having a structure in which graphene structures are laminated. The ratio of elements other than hydrogen among the elements constituting the carbon material (4) was 81.98% for carbon and 18.02% for oxygen. No contained metal component was detected (less than 0.01%).

[Example 5]
660 mg of a black solid (carbon material (5)) was obtained in the same manner as in Example 3, except that the firing temperature was 380° C. and the firing time was 1 hour. When the solubility and solubility/dispersibility of this carbon material (5) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was soluble, partially soluble, and had good dispersibility. there were.
The Raman spectrum and the XRD spectrum of the obtained carbon material (5) are shown in FIG. 11 and FIG. 12, respectively. Since the Raman spectrum has peaks at 1345 cm ⁻¹ , 1600 cm ⁻¹ , 2680 cm ⁻¹ and 2895 cm ⁻¹ , the carbon material (5) has a graphene structure. It was found to be a carbon material containing no carbon-based compounds. In Example 5, since the carbonization temperature was lower than the melting point, the intermolecular reaction was not promoted and it was difficult to form a laminated structure. That is, it can be said that even a compound having a melting point can be carbonized without positively forming a laminated structure. The ratio of elements other than hydrogen among the elements constituting the carbon material (5) was 71.28% for carbon and 28.72% for oxygen. No contained metal component was detected (less than 0.01%).

[Comparative Example 2]
610 mg of a black solid (carbon material (C2)) was obtained in the same manner as in Example 3 except that the firing temperature was 500° C. and the firing time was 1 hour. When the solubility and solubility/dispersibility of this carbon material (C2) were confirmed using N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, it was insoluble and non-dispersible.
The Raman spectrum and the XRD spectrum of the obtained carbon material (C2) are shown in FIG. 13 and FIG. 14, respectively. It has peaks at 1330 cm ⁻¹ , 1595 cm ⁻¹ , 2705 cm ⁻¹ and 2835 cm ⁻¹ in its Raman spectrum and peaks at 25.6° in its XRD spectrum, indicating that it is a kind of carbon material. In addition, the ratio of elements other than hydrogen among the elements constituting the carbon material (C2) was 83.46% for carbon and 16.54% for oxygen.

From the results of Examples 1 to 5, it is found that the maximum molecular weight of the soluble portion is 1,300,000 or less. From this, it can be said that a carbon material having a molecular weight of at least 1,300,000 or less is a carbon material that dissolves in a solvent. . In other words, if the molecular weight exceeds 1,300,000, it is thought that the solubility in the solvent may become poor.

INDUSTRIAL APPLICABILITY The carbon material of the present invention is a novel carbon material that has excellent solubility in solvents compared to conventional carbon materials, can achieve good handleability, and contains substantially no metal components that become impurities. , can be developed for various uses.

Claims (7)

A carbon material,
In the Raman spectrum chart obtained by Raman spectroscopic analysis , G band (within the range of 1550 cm ^-1 to 1650 cm ^-1 ) , G' band (within the range of 2650 cm ^-1 to 2750 cm ^-1 ) , D band ( within the range of 1300 cm ^-1 to 1400 cm ⁻¹ ) and the D+D′ band ( within the range of 2800 cm ⁻¹ to 3000 cm ⁻¹ ),
A carbon-based compound having a molecular weight of 1,000 to 1,300,000, which is soluble in a solvent ,
the solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform and dichloromethane; is at least one selected from the group consisting of
The carbon-based compound is obtained by mixing the carbon material to 0.001% by mass with respect to the solvent, performing ultrasonic treatment for 1 hour, and applying the resulting liquid to PTFE filter paper (pore size 0.45 μm). A carbon material that is contained in the liquid that has passed through the filter paper when it is passed through . 2. The carbon material according to claim 1 , which has a peak within the range of 20° to 30° in an XRD spectrum chart obtained by XRD analysis of said carbon-based compound. 3. The carbon material according to claim 1, which is obtained by heating compound (A) in which a condensation reaction occurs between identical molecules and/or between different molecules upon heating. The carbon material according to claim 3 , wherein the compound (A) is solid and has a melting point in a 23°C environment. The carbon material according to claim 3 or 4 , wherein the heating temperature is (T±50)°C, where T°C is the decomposition temperature of the compound (A). 6. The carbon material according to any one of claims 1 to 5 , which is in a bulk state. A carbon material-containing liquid obtained by dissolving at least part of the carbon material according to any one of claims 1 to 6 in a solvent.

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