Carbon material composition

Abstract

This invention provides a carbon material composition that is effective for coating inorganic materials. [Solution] A carbon material composition comprising a carbon material and a solvent having a structure derived from vicinal diol, wherein the carbon material has peaks in the G band and D band in a Raman spectral chart obtained by Raman spectroscopy, the carbon material comprises a carbon-based compound soluble in an organic solvent, and the organic solvent is at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane.

Description

Technical Field

[0001] The present invention relates to a carbon material composition effective for coating inorganic materials.

Background Art

[0002] Carbon materials (such as graphite, activated carbon, carbon black, graphene, carbon nanotubes, etc.) are used in a wide range of fields. Also, carbon material particles are used in energy fields such as batteries, automotive fields such as tires, and lubrication fields such as solid lubricants.

[0003] Among them, carbon materials that dissolve in solvents (i.e., soluble carbon materials) are widely used in the coating field.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0005] [[ID=4l]]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, soluble carbon materials are used in various fields, but with conventional organic solvents (such as N,N-dimethylformamide, N-methylpyrrolidone, etc.), there have been difficulties in coating specific inorganic materials.

[0007] In view of the above circumstances, the present invention aims to provide a soluble carbon material solution (i.e., a carbon material composition, a carbon material solution) that can be used for coating various inorganic materials. [Means for solving the problem]

[0008] The inventors conducted various studies to achieve the above objective and arrived at the present invention. Specifically, the present invention is a carbon material composition comprising a carbon material and a solvent having a structure derived from vicinaldiol, wherein the carbon material has peaks in the G band and D band in a Raman spectral chart obtained by Raman spectroscopy, the carbon material comprises a carbon-based compound soluble in an organic solvent, and the organic solvent is at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane. [Effects of the Invention]

[0009] By using the carbon material composition of the present invention, it is possible to provide a soluble carbon material solution (i.e., a carbon material composition, a carbon material solution) that can be used to coat various inorganic materials. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. Furthermore, combinations of two or more of the individual preferred embodiments of the present invention described below are also preferred embodiments of the present invention.

[0011] [Carbon materials] The carbon material of the present invention exhibits the following characteristics in the Raman spectrum obtained by Raman spectroscopy: G band (1550 cm⁻¹) -1 ~1650cm -1 (within the range), and D-band (1300cm) -1 ~1400cm -1It is characterized by having a peak within the range of (2650 cm). Furthermore, it is characterized by having a G' band (2650 cm). -1 ~2750cm -1 (within the range) and D+D' band (2800cm) -1 ~3000cm -1 It is also preferable to have a peak within the specified range. Regarding the excitation wavelength in the Raman spectrum, it is possible to select a suitable wavelength. While fluorescence may be emitted depending on the excitation wavelength, soluble carbon materials are inherently amorphous carbon with defects and functional groups; therefore, if the G and D bands are observed, there is a high probability that the G' and D+D' bands are also present. The presence of these peaks indicates that it is a carbon material and can exhibit the effects of a carbon material (such as lubricity).

[0012] The carbon material of the present invention contains a carbon-based compound that is soluble in organic solvents. Conventional carbon materials (such as graphite, activated carbon, carbon black, graphene, and carbon nanotubes) are insoluble in organic solvents. While some may disperse, essentially, solubility in organic solvents means dissolving in them. For example, when passed through a membrane filter (e.g., with pore sizes of 0.45 μm or 0.1 μm), the carbon material of the present invention will pass through. On the other hand, conventional carbon materials cannot pass through. In other words, to determine whether or not a material is soluble, the carbon material is mixed with an organic solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane to a concentration of 0.001% by mass. After sonication for 1 hour, the resulting solution is passed through a GL Chromatodisk (pore size 0.45 μm) manufactured by GL Sciences Co., Ltd. If the carbon material passes through the filter paper, it is considered soluble in that organic solvent.

[0013] The carbon material of the present invention preferably contains a carbon-based compound having a molecular weight of 1,000 to 1,300,000 as determined by GPC analysis. The presence of these peaks in the carbon-based compound enhances its solubility in organic solvents and allows it to exhibit functionality in applications such as coatings.

[0014] The carbon-based compounds of the present invention preferably have peaks in the range of 20° to 30° in the XRD spectral chart obtained by XRD analysis. Having these peaks indicates that the compound is a carbon material and can exhibit the effects of a carbon material (such as lubricity).

[0015] The carbon-based compounds of the present invention are preferably obtained by heating a compound (A) that undergoes condensation reactions between identical and / or heterogeneous molecules upon heating, under any atmosphere. By using this reaction, a carbon-based compound is formed, and it can exhibit the characteristics of a carbon-based compound.

[0016] The carbon-based compounds of the present invention can be obtained, for example, by calcining a polyphenol (a compound having two or more phenolic hydroxyl groups in its structure), such as phloroglucinol, at a low temperature of 300°C or less.

[0017] [Solvents having a structure derived from vicinaldiol] The solvent having a structure derived from vicinal diol of the present invention can dissolve the carbon-based compound of the present invention and can be used for coating various inorganic materials. Examples of the solvent having a structure derived from vicinal diol include those having a structure with OH groups on adjacent carbon bonds such as ethylene glycol and propylene glycol, and each OH group is independently unsubstituted or substituted with a structure such as a -OH group, -O-R group, -O-C=O-R group (R is arbitrarily selected from H, an alkyl group, an aryl group, etc.). Specifically, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monoacetate, propylene glycol monoacetate, etc. can be mentioned. By having a structure derived from vicinal diol, the interaction with the soluble carbon material is strengthened, so that the coordination ability to metal ions is strengthened, and it becomes possible to coat inorganic materials with weak interaction and difficult coating.

[0018] [Carbon material composition] In the carbon material composition of the present invention, the concentration of the carbon material is preferably 0.01 to 50% by mass, more preferably 0.05% to 20%, and most preferably 0.1 to 10%. By being in this range, it can be applied to various uses. The concentration can be adjusted by concentrating by distilling off the solvent by heating or reducing the pressure.

[0019] The carbon material composition of the present invention may contain other components other than the carbon material of the present invention and the solvent having a structure derived from vicinal diol. The other components may be dissolved, dispersed, or insoluble in the solvent having a structure derived from vicinal diol. By containing other components, it can be applied in various uses. [Examples]

[0020] The present invention will be described in more detail 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 "percent mass".

[0021] [Raman spectroscopy measurement] Micro-laser Raman spectroscopy was performed using the following equipment and conditions. Equipment: JASCO NRS-3100 Measurement conditions: Excitation wavelength 532 nm, number of integrations 32 times

[0022] [Molecular weight measurement] GPC measurements were performed using the following equipment and conditions, and the maximum molecular weight was estimated from the peak rise time. Equipment: Tosoh HLC-8220GPC Column: TSKgel superH-RC Developing solvent: N,N-dimethylformamide (with 0.1% lithium bromide added)

[0023] [Solubleness evaluation] To evaluate solubility in organic solvents, the carbon material was mixed with N,N-dimethylformamide to a concentration of 0.001% by mass, and sonication was performed for 1 hour. The resulting solution was passed through a GL Chromatographic Disc (pore size 0.45 μm) manufactured by GL Sciences Co., Ltd., and solubility was determined if the carbon material passed through the chromatographic disc.

[0024] [Thermogravimetric analysis measurement] Thermogravimetric analysis was performed using the following equipment and conditions. The inorganic particles and the coated particles after coating with the carbon material composition of the present invention were analyzed, and the coating amount and coating rate were calculated from the weight difference before and after heating. Percentage of residual weight of inorganic particles before and after heating at 700°C (A(%)) Percentage of residual weight of coated particles before and after heating at 700°C B (%) The ratio of carbon material content of coated particles to inorganic particles C = (AB) / B Coverage rate (empirical formula) = 100 × C × ρ × d (%) (ρ: particle density, d: volume-based average particle diameter) Equipment: Netch TG-DSC Conditions: Analysis under airflow, heating rate of 10°C / min up to 700°C

[0025] [Lubrication properties evaluation] The lubrication characteristics were evaluated using the following equipment and conditions, and the average coefficient of dynamic friction for each sliding rotation was measured. Equipment: Static friction testing machine (manufactured by Trinity Labs Co., Ltd.) Contact element: 6mmφ SUS ball contact element, substrate: SUS304, Load: 1000g, Sliding speed: 10mm / sec, Sliding distance: 10mm Number of sliding cycles: 100 (The average coefficient of kinetic friction for each cycle was calculated)

[0026] [Examples of carbon material preparation 1, 2] Carbon materials (1) and (2) were obtained by heating phloroglucinol in a glass tube oven under a nitrogen atmosphere at 250°C (Preparation Example 1) or 300°C (Preparation Example 2) for 1 hour. Carbon materials (1) and (2) contained components with molecular weights ranging from 1,000 to 1,300,000. Raman spectroscopy revealed G, D, G', and D+D' bands for each. They were also soluble in N,N-dimethylformamide. Furthermore, XRD analysis revealed peaks in the 20° to 30° range in the XRD spectral chart.

[0027] [Examples and Comparative Examples] Carbon material solutions were obtained by dissolving carbon materials (1) and (2) in the solvents shown in Table 1 at a concentration of 1% by mass.

[0028] [Evaluation Example 1] The carbon material solutions obtained in the examples and comparative examples were applied to SUS304 substrates and dried to form carbon material coatings, and their lubricity was evaluated. An average dynamic friction coefficient of 0.2 or higher after 100 cycles was marked with ×, and a value of less than 0.2 was marked with ○. The evaluation results are shown in Table 1.

[0029] [Evaluation Example 2] The carbon material solutions obtained in the examples and comparative examples were mixed and stirred with magnesium oxide particles. The coated particles were then washed with the carbon material solutions prepared in the examples and comparative examples, and the coating rate of the resulting powder after drying was calculated by thermogravimetric analysis. A coating rate of less than 90% was marked with ×, and 90% or more was marked with ○. The evaluation results are shown in Table 1.

[0030] The results from evaluation examples 1 and 2 show that using a solvent with a structure derived from vicinal diol improved the coating strength (adhesion and lubricity) on SUS304 and the coating strength (adhesion and coverage) on magnesium oxide.

[0031] [Table 1]

[0032] The present invention allows for the use of a carbon material composition that is effective for coating inorganic materials.

Claims

1. A carbon material composition comprising a carbon material and a solvent having a structure derived from vicinal diol, The carbon material has peaks in the G band and D band in the Raman spectral chart obtained by Raman spectroscopy. The carbon material comprises a carbon-based compound that is soluble in an organic solvent. A carbon material composition wherein the organic solvent is at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane.

2. The carbon material composition according to claim 1, wherein the molecular weight of the carbon-based compound is 1,000 to 1,300,000.

3. The carbon material composition according to claim 1 or 2, characterized in that the carbon material further has peaks in the G' band and / or the D+D' band in the Raman spectral chart obtained by Raman spectroscopy.

4. The carbon material composition according to claim 1 or 2, wherein the solvent having a structure derived from vicinaldiol is at least one selected from the group consisting of ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monoacetate, and propylene glycol monoacetate.

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