WO2018167976A1 - Nanocarbon obtained by removing ammonium ion group from nanocarbon having amino group in molecular skeleton, organic solvent dispersion thereof, and method for producing same - Google Patents

Abstract

Provided are: nanocarbon that exhibits high dispersibility not only in polar organic solvents but also non-polar organic solvents, even when dispersed alone without using a dispersant or the like; and a dispersion of the nanocarbon. Specifically provided are: nanocarbon obtained by aminating nanocarbon which has an oxygen functional group in the molecular skeleton thereof and then removing an ammonium group; and an organic solvent dispersion threof.

Description

Nanocarbon obtained by removing ammonium ionic group from nanocarbon having amino group in molecular skeleton, organic solvent dispersion thereof, and production method thereof

The present invention relates to a nanocarbon, a nanocarbon dispersion, and a method for producing them.

In recent years, nanocarbons have excellent mechanical strength, electrical conductivity, thermal conductivity, thermal stability, etc., so research and development aimed at the use of metal substitutes and lithium ion battery and supercapacitor electrode materials, etc. Is being actively conducted.

However, nanocarbon is difficult to handle because it easily aggregates, and when dispersed in an organic solvent, there are many attempts to suppress aggregation by adding a dispersant to this (see Patent Documents 1 and 2). There is also an example in which nanocarbon is dispersed in a base oil by a surfactant (see Patent Document 3). However, the dispersant itself is an impurity for nanocarbon, and adding this is a trade-off with the risk of impairing the function of the nanocarbon. In addition, there is an example in which dispersibility in water is improved by controlling the degree of oxidation of graphite oxide or graphene oxide (see Patent Document 5). However, there is no disclosure about the degree and dispersibility of the organic solvent.

As described above, these conventional techniques require additives such as dispersants, and when carbon in these dispersed states is observed with an electron microscope, they are not formed into a single layer in an organic solvent. In most cases, they overlap to form a multilayer or an aggregate.

This overlap reduces the dispersibility of the nanocarbon in the organic solvent and impairs the dispersion stability. Accordingly, there has been a demand for nanocarbon dispersions in which the dispersion state is stably maintained in a wide range of organic solvents. In particular, there has been a strong demand for a dispersion in which nanocarbon is dispersed alone without using a dispersion aid such as a dispersant.

JP2012-82120A Japanese Patent Laid-Open No. 2015-29947 JP 2016-47875 A Japanese Patent Laying-Open No. 2015-059079 Japanese Patent Laid-Open No. 2015-160766

The technology to suppress the aggregation of nanocarbon and stably disperse it in the solvent is important. However, as described above, since the nanocarbon itself is likely to aggregate, the current technique is generally a technique in which an auxiliary agent such as a dispersant is forcibly dispersed. However, the dispersion of nanocarbon using a dispersant, for example, when this is used to form a thin film by a casting method or the like, the spacing between the nanocarbons increases due to the presence of the dispersant, and the conductivity is increased. To lose. In other words, the conventional technique of adding a dispersant is a problem that must be improved by back-to-back with the risk of impairing the function of nanocarbon.

Therefore, the present invention has been made on the basis of the above background art and recognition of its problems. That is, the present invention relates to a highly dispersible nanocarbon that exhibits stable dispersibility in a wide variety of organic solvents including not only polar organic solvents but also nonpolar organic solvents, and this is highly stable as an organic solvent. The object is to provide a dispersed dispersion.

The present inventor has obtained a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, and an amino group in the molecular skeleton and no ammonium ionic group. When studying a method for providing a dispersion in which nanocarbon is highly stably dispersed in an organic solvent, it is not necessary to use a special additive, and especially for a wide variety of organic solvents. The present invention was completed by finding stable dispersion.

The present inventor has repeatedly studied to chemically modify nanocarbon molecules in order to solve the above problems. As a result, in order to improve the dispersion stability of nanocarbon in an organic solvent, it was found that it is effective to modify the nanocarbon molecule with an alkylamino group. On the other hand, during the modification, acidic functional groups (for example, carboxyl groups) on the nanocarbon molecular skeleton react with amines to form ammonium ionic groups, and electrostatic interactions derived from these groups. However, unexpectedly, it has also been found that it promotes aggregation of nanocarbon molecules.

Therefore, the present invention was made based on these findings. That is, when a nanocarbon having an amino group is obtained by modifying the nanocarbon with an alkylamine, an ammonium ionic group in which an acidic functional group (for example, a carboxyl group) in the nanocarbon molecule is ionically bonded to the alkylamine is by-produced. In addition, nanocarbon obtained by removing ammonium ionic group from nanocarbon having amino group in the molecular skeleton, and nanocarbon having amino group in molecular skeleton and not having ammonium ionic group The above problem has been solved by finding that the action of agglomerating carbon in an organic solvent is significantly suppressed as compared with conventional nanocarbon.

That is, a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, and a nanocarbon having an amino group in the molecular skeleton and no ammonium ionic group. The present invention has been found to exhibit stable dispersibility in a wide variety of organic solvents including not only polar organic solvents but also nonpolar organic solvents, without the need for a dispersant or the like. Was completed.

In order to solve the above-described problems, a method for providing a dispersion in which nanocarbon is highly stably dispersed in an organic solvent is described below. That is, a nanocarbon obtained by aminating a nanocarbon having an oxygen functional group in the molecular skeleton, and subsequently removing the ammonium ionic group, and an amino group in the molecular skeleton and an ammonium ionic group. The first means for synthesizing nanocarbons that do not have this and the second means for providing a dispersion in which these were dispersed in a wide variety of organic solvents were used.

That is, the present invention is a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, and an amino group in the molecular skeleton and an ammonium ionic group. The present invention relates to non-nanocarbons and dispersions in which these are highly stably dispersed in an organic solvent, and further to a method for producing them.

The nanocarbon according to the present invention includes those obtained by removing an ammonium ionic group from nanocarbon having an amino group in the molecular skeleton.

The nanocarbon according to the present invention includes a nanocarbon having an amino group in the molecular skeleton and no ammonium ion group.

The nanocarbon according to the present invention is graphene oxide obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, or an amino group in the molecular skeleton and an ammonium ionic group. The graphene oxide which does not have may be sufficient.

In the method for producing nanocarbon according to the present invention, an amine ionic property is obtained by allowing an amine dissolved in a solvent to act on a dispersion of nanocarbon having an oxygen functional group in the molecular skeleton, and subsequently causing an acid to act on the product. A step of removing the group may be included.

The nanocarbon dispersed in the dispersion according to the present invention is a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, an amino group in the molecular skeleton, and ammonium. Nanocarbon without ionic groups, graphene oxide obtained by removing ammonium ionic groups from graphene oxide with amino groups in the molecular skeleton, or ammonium ionic groups with amino groups in the molecular skeleton It may be any of graphene oxide that does not have.

In the method for producing a dispersion according to the present invention, an amine ionic property is obtained by allowing an amine dissolved in a solvent to act on a nanocarbon dispersion having an oxygen functional group in the molecular skeleton, and subsequently causing an acid to act on the product. A step of removing the group may be included.

The amine that acts on the nanocarbon according to the present invention may be a primary or secondary amine in which the substituent on the nitrogen atom is a hydrocarbon group having 4 to 26 carbon atoms.

In the method for producing nanocarbon according to the present invention, the amine to be acted on may be a primary or secondary amine in which the substituent on the nitrogen atom is composed of a hydrocarbon group having 4 to 26 carbon atoms.

The amine that acts on the nanocarbon used in the nanocarbon dispersion according to the present invention may be a primary or secondary amine in which the substituent on the nitrogen atom is composed of a hydrocarbon group having 4 to 26 carbon atoms.

In the method for producing a nanocarbon dispersion according to the present invention, the amine to be actuated may be a primary or secondary amine in which a substituent on a nitrogen atom is composed of a hydrocarbon group having 4 to 26 carbon atoms.

In the amine that acts on the nanocarbon according to the present invention, the substituent on the nitrogen atom may have an unsaturated bond or an aromatic group in a part of its structure.

In the method for producing nanocarbon according to the present invention, the amine to be acted on may have a substituent on the nitrogen atom having an unsaturated bond or an aromatic group in a part of its structure.

In the amine that acts on the nanocarbon used in the nanocarbon dispersion according to the present invention, the substituent on the nitrogen atom may have an unsaturated bond or an aromatic group in a part of its structure.

In the method for producing a nanocarbon dispersion according to the present invention, the amine to be acted on may have a substituent on a nitrogen atom having an unsaturated bond or an aromatic group in a part of its structure.

The amines acting on the nanocarbon according to the present invention are butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearyl. One or two or more amines selected from amine, N-methyloctadecylamine, and polyethylene glycol stearylamine may be used.

In the method for producing nanocarbon according to the present invention, the acted amine is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyl. One or two or more amines selected from dodecylamine, stearylamine, N-methyloctadecylamine, and polyethylene glycol stearylamine may be used.

The amines that act on the nanocarbon used in the nanocarbon dispersion according to the present invention are butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2 -One or two or more amines selected from octyldodecylamine, stearylamine, N-methyloctadecylamine, polyethylene glycol stearylamine may be used.

In the method for producing a nanocarbon dispersion according to the present invention, the amine to be acted on is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2 -One or two or more amines selected from octyldodecylamine, stearylamine, N-methyloctadecylamine, polyethylene glycol stearylamine may be used.

The organic solvent used in the nanocarbon dispersion according to the present invention may have a dielectric constant (ε) of 2 or more.

In the method for producing a nanocarbon dispersion according to the present invention, the organic solvent in which nanocarbon is dispersed may have a dielectric constant (ε) of 2 or more.

The organic solvent used in the nanocarbon dispersion according to the present invention may have a viscosity (Pa · S) at 20 ° C. of 1 × 10 ⁻⁴ or more.

In the method for producing a nanocarbon dispersion according to the present invention, the organic solvent in which nanocarbon is dispersed may have a viscosity (Pa · S) at 20 ° C. of 1 × 10 ⁻⁴ or more.

Organic solvents used in the nanocarbon dispersion according to the present invention are saturated or unsaturated hydrocarbon solvents such as hexane, petroleum ether, toluene, xylene, light oil, polyolefin, 1-methoxy-2-propanol, ethanol, butanol, Alcohol solvents containing polyhydric alcohols such as 2-ethylhexanol, ethylene glycol, glycerin, ether solvents such as ethyl cellosolve, dimethoxyethane, tetrahydrofuran, cyclopentyl methyl ether, ethyl acetate, butyl acetate, 2-ethylhexyl acetate, acrylic Ester solvents such as methyl acid, methyl methacrylate, halogen solvents such as dichloromethane and trichloroethylene, amide solvents such as formamide, dimethylformamide, dimethylacetamide, acetone, methyl ethyl ketone, The solvent may be one selected from ketone solvents such as methyl isobutyl ketone and cyclohexanone, nitrile solvents such as acetonitrile and acrylonitrile, or a mixed solvent of two or more solvents.

In the method for producing a nanocarbon dispersion according to the present invention, the organic solvent in which nanocarbon is dispersed is saturated or unsaturated hydrocarbon solvent such as hexane, petroleum ether, toluene, xylene, light oil, polyolefin, 1-methoxy- Alcohol solvents containing polyhydric alcohols such as 2-propanol, ethanol, butanol, 2-ethylhexanol, ethylene glycol, glycerin, ether solvents such as ethyl cellosolve, dimethoxyethane, tetrahydrofuran, cyclopentyl methyl ether, ethyl acetate, butyl acetate , Ester solvents such as 2-ethylhexyl acetate, methyl acrylate and methyl methacrylate, halogen solvents such as dichloromethane and trichloroethylene, amides such as formamide, dimethylformamide and dimethylacetamide The solvent may be one selected from ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, nitrile solvents such as acetonitrile and acrylonitrile, or a mixed solvent of two or more solvents.

According to the present invention, a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, and an amino group in the molecular skeleton and an ammonium ionic group. It is possible to provide a non-nanocarbon and an organic solvent dispersion in which they are stably dispersed in an organic solvent of a kind widely including not only a polar organic solvent but also a nonpolar organic solvent.

FIG. 1 is an example of a structural formula of graphene oxide obtained by removing an ammonium ionic group and having an amino group according to the present invention. 6 is an infrared spectral absorption spectrum of the graphene oxide used in Example 1. FIG. FIG. 4 is an infrared spectral absorption spectrum of graphene oxide showing that the absorption intensity at a carboxyl group of 1715 cm ⁻¹ was significantly reduced by the formation of ammonium ionic groups in Comparative Example 2. FIG. 7 shows that the absorption intensity at 2800 to 3000 cm ⁻¹ presumed to be derived from the introduction of the alkyl group of Example 1 according to the present invention was remarkably increased and 1715 cm presumed to be derived from the re-formation of the carboxyl group. ² is an infrared spectral absorption spectrum of graphene oxide indicating that absorption at ⁻¹ exists. FIG. 3 is a photograph of a graphene oxide dispersion obtained by removing the ammonium ionic groups having amino groups dispersed sufficiently in a single layer state according to the present invention. FIG. 2 is an electron micrograph of graphene oxide obtained by removing the ammonium ionic group having an amino group, which is sufficiently peeled, ie, dispersed in a single layer state according to the present invention. Although two to three layers of graphene oxide can be confirmed, it is thought that they were stacked in the process of dropping on the substrate and drying. In the liquid, all are considered to be dispersed in a single layer. FIG. 5 is a photograph of the graphene oxide dispersion of Comparative Example 2 with insufficient peeling. 4 is an electron micrograph of graphene oxide of Comparative Example 2 with insufficient peeling. FIG. 10 is a diagram showing an example of a method for producing an organic solvent dispersion of graphene oxide having an amino group and obtained by removing an ammonium ionic group according to an embodiment of the present invention.

As a result of intensive studies, the present inventors have found that nanocarbons obtained by removing ammonium ionic groups from nanocarbons having amino groups in the molecular skeleton, and those having amino groups in the molecular skeleton and ammonium The present invention was completed by finding that nanocarbons having no ionic group exhibit stable dispersibility in a wide variety of organic solvents including not only polar organic solvents but also nonpolar organic solvents.

That is, the present invention relates to a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, and a nanocarbon having an amino group in the molecular skeleton and no ammonium ionic group. Carbon, their organic solvent dispersions, and their production methods.

According to the present invention, nanocarbons exhibiting highly stable dispersibility in a wide variety of organic solvents and dispersions thereof are provided.

The nanocarbon of the present invention does not require additives such as a dispersant when dispersed in an organic solvent. Therefore, there is no possibility that the physical properties and functions inherent to the nanocarbon may be reduced or lost by adding the additive. In addition, there is an advantage in terms of improving economic efficiency and environmental compatibility.

First, a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton of the present invention, and an amino group in the molecular skeleton and an ammonium ionic group. Summarize the production method of non-nanocarbon and its organic solvent dispersion. A nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton according to the present embodiment, and an amino group in the molecular skeleton and no ammonium ionic group. In the method for producing nanocarbon, a nanocarbon dispersion liquid having an oxygen functional group in a molecular skeleton is aminated by adding an amine dissolved in an organic solvent under stirring. Nanocarbon obtained by removing ammonium ion group from nanocarbon having amino group in the molecular skeleton by acid treatment of the obtained reaction solution and purification by methods such as centrifugation, filtration, dialysis, or A nanocarbon having an amino group in the molecular skeleton and no ammonium ion group is obtained. This is isolated by drying or the like, and then added with a desired organic solvent, and imparts physical stimulation such as ultrasonic waves to promote dispersion, thereby improving the dispersibility of the nanocarbon.

That is, one embodiment of the present invention is a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, or an amino group having an amino group in the molecular skeleton and an ammonium ionic property. The present invention relates to a nanocarbon having no group and a production method thereof.

Here, the nanocarbon having an oxygen functional group in the molecular skeleton is a nanocarbon having an oxirane structure in the molecular skeleton. For example, graphene oxide, graphite oxide, oxidized carbon nanotube, or oxidized fullerene (C ₆₀ ) is included.

The nanocarbon having an oxygen functional group in the molecular skeleton is a known method using a corresponding graphite, carbon nanotube, fullerene (C ₆₀ ), or the like, for example, an oxidizing agent such as potassium permanganate or potassium chlorate. It can be obtained by oxidation with. During the oxidation process, in addition to the oxirane group (a functional group in which one oxygen atom is inserted into the carbon / carbon double bond), so-called acidic functional groups such as hydroxyl groups and carboxyl groups are often added to the nanocarbon skeleton. However, these may be included (see FIG. 1 showing graphene oxide as an example).

First, as shown in FIG. 9, a dispersion liquid in which nanocarbon having an oxygen functional group in the molecular skeleton is dispersed is prepared. In this embodiment, the dispersion medium of the dispersion liquid may be a medium in which nanocarbon having an oxygen functional group in the molecular skeleton is relatively easily dispersed, and is generally water. The nanocarbon having an oxygen functional group in the molecular skeleton is preferably dispersed as much as possible in the dispersion. The thickness of the nanocarbon having an oxygen functional group in the molecular skeleton is preferably nano-sized (for example, 1 nm).

The method for producing nanocarbon having an oxygen functional group in the molecular skeleton and a dispersion thereof is not particularly limited. For example, when the nanocarbon is graphene oxide, a method such as a Brodie method, a Staudenmeier method, a Hummers method, or an improved Hummers method (see Japanese Patent Application Laid-Open No. 2015-160766) may be used. For example, according to the modified Hummers method, graphite is oxidized and peeled by adding sulfuric acid and an oxidizing agent to react with it. Subsequently, when water is added and centrifugation is performed a plurality of times, an aqueous dispersion of graphene oxide is obtained.

In the nanocarbon having an oxygen functional group, the content ratio of oxygen atoms to carbon atoms (O / C) is preferably 0.1 to 1, and more preferably 0.4 to 0.8.

Next, the amination of nanocarbon having an oxygen functional group can be carried out by allowing an amine dissolved in an organic solvent to act on the nanocarbon aqueous dispersion prepared by the above-described method.

The concentration of nanocarbon in the nanocarbon dispersion used for the amination reaction may be 0.01% to 2% in terms of the weight ratio of nanocarbon to the volume of the dispersion. If the concentration is higher than this, sufficient agitation cannot be performed, and if the concentration is lower, the amount of carbon obtained at one time is reduced, which is inefficient.

Next, prepare a dispersion in which amine is dispersed or dissolved. The amine used in the present invention is preferably a primary or secondary amine in which the substituent on the nitrogen atom is a hydrocarbon group having 4 to 26 carbon atoms. At this time, the substituent on the nitrogen atom may have an unsaturated bond or an aromatic group in a part of its structure. Among them, for example, butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearylamine, N-methyloctadecylamine, Polyethylene glycol stearylamine is preferably used.

The amine is usually dispersed or dissolved in an organic solvent and subjected to the amination of the present invention. Any organic solvent may be used as long as it can be easily mixed with a dispersion in which nanocarbon having an oxygen functional group in the molecular skeleton is dispersed. Usually, since the dispersion medium of nanocarbon having an oxygen functional group in the molecular skeleton is mostly water, it may be a polar solvent that is easily miscible with it. For example, ethanol, propanol, solmix, dimethylformamide, N-methylmorpholine, dimethyl sulfoxide and the like can be mentioned.

The concentration of the amine dispersed or dissolved in the organic solvent is preferably 0.01 to 50% by weight ratio of the amine to the capacity of the organic solvent. For example, when the concentration of nanocarbon in the dispersion of nanocarbon is selected from the range of 0.1 mg / ml to 30 mg / ml, the amine concentration is from 0.02 to 30 mg / ml. You can choose.

The amination of the nanocarbon can be performed by mixing the amine dispersion prepared above and the nanocarbon dispersion having the oxygen functional group prepared above. This mixing method does not require any special method. Usually, the former amine dispersion may be added to the latter nanocarbon dispersion having an oxygen functional group while stirring.

The reaction temperature in the amination reaction may be selected in consideration of the reactivity of the amine to be used and the physical properties of the dispersion medium, and is not particularly limited as long as each liquid can maintain a liquid phase, but is usually 0 ° C. to 150 ° C. What is necessary is just to carry out on the atmospheric pressure conditions of ℃. When the reactivity of the amine is not sufficiently high, the amine dispersion and the nanocarbon dispersion can be put in a pressure resistant vessel and further reacted under a high temperature condition.

The reaction time in the amination reaction may be selected in consideration of the reactivity of the amine to be used and the reaction temperature, but it is usually preferably 0.5 to 48 hours.

What is necessary is just to dry after centrifugation, filtration, etc.
Moreover, it is not always necessary to isolate. The reaction mixture may be subsequently subjected to a step of removing ammonium ion groups.

When the aminated nanocarbon thus obtained contains an acidic functional group such as a hydroxyl group and a carboxyl group in the molecular skeleton of the nanocarbon containing an oxygen functional group as a raw material, Ammonium ionic groups reacted with the starting amine are often included as a by-product. As described above, since it has been clarified that this ammonium ionic group has a property of promoting aggregation between nanocarbon molecules, the ammonium ionic group must be excluded.

In order to exclude the ammonium ionic group, it is effective to subject it to acid decomposition, that is, addition of an acid. The acid to be added is not particularly limited as long as it has higher acidity than that of the phenolic hydroxyl group or carboxyl group on the nanocarbon skeleton. Of these, hydrochloric acid, sulfuric acid, paratoluenesulfonic acid and the like can be used inexpensively and easily.

The above-described acid decomposition step can be completed simply by adding the above-mentioned acid to the aminated nanocarbon dispersion at room temperature and stirring for a certain period of time. The end point of this step may be a point when the dispersibility of the nanocarbon is improved. For example, the red color may be confirmed with a pH test paper.
The thus obtained dispersion after acid decomposition has a target ammonium ionic property that has an amino group in the molecular skeleton and an acid functional group such as a carboxyl group that reacts with the starting amine to form a by-product. The nanocarbon from which the group is removed is generated.

Nanocarbon obtained by removing ammonium ionic groups from nanocarbons having amino groups in the molecular skeleton, or nanocarbons having amino groups in the molecular skeleton and no ammonium ionic groups. Carbon can be purified by a conventional method such as centrifugation, filtration or dialysis, or can be isolated by concentration. For example, the acid-decomposed dispersion is subjected to centrifugation to obtain a precipitate once. By further centrifuging this with a dispersion medium such as water or hydrous alcohol, impurities such as amine and acid of raw materials remaining excessively in the amination reaction or acid salts of these amines are removed. And can be purified.

In this purification, the amine and the acid salt of amine may be difficult to remove sufficiently by adsorbing to nanocarbon. However, the amine acid salt may remain in the preparation of the nanocarbon organic solvent dispersion of the present invention. The present inventors have separately confirmed that the acid salt of the amine has a positive effect on the dispersion stability of the organic solvent dispersion of the present invention, but does not have a negative influence.

The purified precipitate thus obtained is subjected to conventional drying means such as vacuum drying, hot air heating drying, freeze drying, and the like, from the nanocarbon having an amino group in the target molecular skeleton to ammonium ions. The nanocarbon obtained by removing the functional group or the nanocarbon having an amino group in the molecular skeleton and no ammonium ion group is isolated as a powder.
This can be subjected to a subsequent step of producing an organic solvent dispersion. From the viewpoint of ease of operation, the purified precipitate may be subjected to a subsequent step of producing an organic solvent dispersion without any special treatment such as drying.
In this way, it is obtained by removing ammonium ionic groups from nanocarbons having an amino group in the molecular skeleton, which shows highly stable dispersibility in a wide variety of organic solvents, which is one form of the present invention. Or a nanocarbon having an amino group in the molecular skeleton and no ammonium ion group.

Another aspect of the present invention is a nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, or an ammonium ionic group having an amino group in the molecular skeleton. This is a method for producing an organic solvent dispersion in which nanocarbons having no carbon are stably dispersed in an organic solvent widely including not only polar organic solvents but also nonpolar organic solvents.

A nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton, isolated by the method described above, and an ammonium ionic group having an amino group in the molecular skeleton. Nanocarbons that do not have can be stably dispersed in organic solvents that include not only polar organic solvents but also nonpolar organic solvents.
The dispersion method does not require any special procedure, and usually a desired organic solvent and nanocarbon are mixed, and a dispersion means for applying a physical stimulus such as stirring and shaking to the mixture may be provided. As the dispersing means, for example, ultrasonic irradiation can be adopted as a simple and efficient method.

The nanocarbon obtained by removing an ammonium ionic group from a nanocarbon having an amino group in the molecular skeleton of the present invention, or a nanocarbon having an amino group in the molecular skeleton and no ammonium ionic group. The organic solvent used for dispersing the carbon is preferably one having a dielectric constant (ε) of 2 or more because it provides a stable dispersion. The organic solvent to be used is preferably one having a viscosity (Pa · S) of 1 × 10 ⁻⁴ or more because it gives a stable dispersion.
Specifically, there are many saturated or unsaturated hydrocarbon solvents such as pentane, hexane, petroleum ether, benzene, toluene, xylene, light oil, polyolefin, ethanol, butanol, 2-ethylhexanol, decanol, ethylene glycol, glycerin, etc. Alcohol solvents including monohydric alcohols, ether solvents such as ethyl cellosolve, dimethoxyethane, tetrahydrofuran, dioxane, cyclopentyl methyl ether, ester solvents such as ethyl acetate, butyl acetate, 2-ethylhexyl acetate, methyl acrylate, methyl methacrylate Solvents, halogen solvents such as dichloromethane, chloroform, trichloroethylene, amide solvents such as formamide, dimethylformamide, dimethylacetamide, acetone, methyl ethyl ketone, methyl iso Ethyl ketone, cyclopentanone, ketone solvents such as cyclohexanone, acetonitrile, nitriles such as acrylonitrile, and the like.

Thus, another form of the present invention, nanocarbon obtained by removing ammonium ionic group from nanocarbon having an amino group in the molecular skeleton, or having an amino group in the molecular skeleton, In addition, an organic solvent dispersion in which nanocarbons having no ammonium ionic group are stably dispersed in a wide variety of organic solvents including not only polar organic solvents but also nonpolar organic solvents can be obtained.

By using the highly dispersible nanocarbon organic solvent dispersion liquid of the present invention obtained in this way, it is easy to produce an electrode of a power storage device and a conductive resin without reducing the functions inherent to nanocarbon. Become. Further, even in a form using the nanocarbon organic solvent dispersion itself, high reliability is maintained from the viewpoint of quality stability over time.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

(1) Production of graphene oxide dispersion First, 3 g of graphite was added to 90 mL of sulfuric acid and ice-cooled. Thereafter, 9 g of potassium permanganate was added and stirred at 35 ° C. for 2 hours. Thereafter, the reaction solution was ice-cooled again, 90 mL of water was added thereto, 3 mL of 30% hydrogen peroxide solution was added, and the mixture was stirred at room temperature for 30 minutes. The reaction mixture was repeatedly centrifuged using water, and sulfuric acid and manganese salts were removed from the product to obtain an aqueous dispersion of graphene oxide (see Patent Document 5).
Subsequently, the dispersion was subjected to centrifugation, and the supernatant was removed to obtain 120 g of a black viscous precipitate. It was confirmed that 4.2 g of graphene oxide was converted to a solid by drying a part of this sediment under reduced pressure. The oxygen content in graphene oxide was 55% by weight (value obtained by subtracting the proportions of C, H, and N from 100% by CHN organic element analysis).
By adding water to the remaining black viscous precipitate and uniformly dispersing it, an aqueous dispersion containing 1% by weight of graphene oxide was prepared and subjected to subsequent amination and comparative examples.

(2) Amination of graphene oxide Next, 200 g of the aqueous dispersion of graphene oxide prepared above was weighed and stirred with a mixer to prepare 1% by weight of oleylamine in the solmix. 200 g of the solution was added dropwise and stirred as it was for 1 minute. The resulting reaction mixture was divided into two equal parts, one for subsequent acid treatment and the other for comparative example 2.

(3) One amination reaction solution obtained by acid treatment was acidified at room temperature with stirring until 1 M sulfuric acid was added thereto until the universal pH test paper turned red.

(4) Purification The acid-treated reaction solution obtained is subjected to centrifugation to once separate acidic components, then once with water, then once with 50% aqueous ethanol, and then twice with Solmix. It was purified by separation.

(5) Preparation of Organic Solvent Dispersion Solmix was removed by adding 1-methoxy-2-propanol to the precipitate obtained by centrifugation in the purification step and performing centrifugation. The black viscous precipitate thus obtained was divided into two equal parts, and one was subjected to vacuum drying to obtain 0.65 g of a black powdery product. The infrared spectral absorption spectrum of this product has an increased absorption intensity at 2800 to 3000 cm ⁻¹ compared to that of graphene oxide, suggesting that a long-chain alkyl group was introduced (FIGS. 2 and 3). reference). In addition, since the ammonium ionic group formed by the reaction of the acidic functional group (carboxyl group) in the graphene oxide molecular skeleton and oleylamine is removed by acid washing, the absorption intensity at the carboxyl group 1715 cm ⁻¹ is compared with that described later. There was a marked increase compared to that observed in Example 2 (see FIGS. 3 and 4).
In addition, even when this black powder product was subjected to Soxhlet extraction using ethanol as an extraction solvent, no significant weight loss was observed in the recovered weight.
From the above, it was confirmed that this black powder product was obtained by covalently introducing oleylamine into the graphene oxide molecular skeleton and removing the ammonium ionic group.

(6) Dispersion The other black viscous sediment was dispersed by adding 1-methoxy-2-propanol (25 ml) and irradiating with ultrasonic waves for 5 minutes. The obtained dispersion liquid did not precipitate at all even after standing for one month, and had a high degree of dispersibility (see FIG. 5). From the results of electron microscopic analysis, it was confirmed that graphene oxide having amino groups was dispersed in 1-methoxy-2-propanol exclusively in a single layer state (see FIG. 6).

In Example 1, the result of having performed reaction and a post-process like Example 1 except having changed the used oleylamine into the amine shown below is shown. The symbol for evaluation is that the obtained 1-methoxy-2-propanol dispersion is left to stand for one month and the dispersibility is equal to or higher than that of Example 1, ◎, slightly inferior, and inferior X.

Ethylamine ○
Ethanolamine ○
Diethylamine ○
Aniline ○
Hexylamine ◎
Benzylamine ◎
Dodecylamine ◎
Phenethylamine ◎
2-Octyldodecylamine ◎
Stearylamine ◎

The results of performing the reaction and post-treatment in the same manner as in Example 1 except that 1-methoxy-2-propanol used in Example 1 was changed to the following solvents are shown. The symbol for evaluation was ◎ when the dispersibility after standing for one month was equal to or higher than that of Example 1, and × when it was inferior.
Dimethylformamide ◎
N-methylpyrrolidone ◎
n-Hexane ◎
Xylene ◎
Base oil ◎
Butyl acetate ◎
Methyl ethyl ketone ◎
Ethylene glycol ◎
n-Propanol ◎
Motor oil SAE40 ◎
Olive oil ◎
Glycerin ◎
Styrene ◎

Comparative Example 1

100 g of an aqueous dispersion containing 1% by weight of graphene oxide prepared in Example 1 was weighed and centrifuged to remove water. When 1-methoxy-2-propanol (50 ml) was added thereto and dispersed by irradiating ultrasonic waves for 5 minutes, colorlessness was observed at the top of the container, and clear sedimentation was observed at the bottom. From the results of electron microscope analysis, it was confirmed that graphene oxide was present in 1-methoxy-2-propanol exclusively in a multilayered state and was not sufficiently dispersed.

Comparative Example 2

In Example 1, the reaction mixture that was not subjected to acid treatment after amination was purified by centrifuging once with water and then twice with Solmix. Solmix was removed by adding 1-methoxy-2-propanol and centrifuging the resulting precipitate. A small amount of the resulting black viscous precipitate was dried under reduced pressure to obtain a black powdery product. The infrared spectral absorption spectrum of this product showed an increase in absorption intensity at 2800 to 3000 cm ⁻¹ compared to that of graphene oxide, suggesting that a long-chain alkyl group was introduced. In addition, the presence of an ammonium ionic group by-produced by the reaction of the acidic functional group (carboxyl group) in the graphene oxide molecular skeleton with oleylamine clearly reveals that the absorption intensity at the carboxyl group 1715 cm ⁻¹ has disappeared. It was recognized (see FIG. 3). From this, this black powdery product is ammonium produced by reaction of oleylamine with an acidic functional group (carboxyl group) in the graphene oxide molecular skeleton, and oleylamine is covalently introduced into the graphene oxide molecular skeleton. Presumed to have an ionic group.
The remaining black viscous precipitate obtained was dispersed by adding 1-methoxy-2-propanol (50 ml) thereto and irradiating with ultrasonic waves for 5 minutes. The dispersion thus obtained was colorless at the top of the container and clearly settled at the bottom (see FIG. 7). Further, from the result of electron microscope analysis, it was confirmed that it was present in 1-methoxy-2-propanol exclusively in a multilayer state and was not sufficiently dispersed (see FIG. 8).

According to the present invention, the nanocarbon is highly stable against a kind of organic solvent widely including not only a polar organic solvent but also a nonpolar organic solvent without requiring a dispersant or the like. A dispersion is provided.
The dispersion of the present invention is useful as a raw material for electrodes of power storage devices such as lithium ion secondary batteries and supercapacitors. The dispersion of the present invention can also be used for the production of functional coating agents such as transparent conductivity, antistatic properties, thermal conductivity and gas barrier properties, and functional films. Furthermore, when blended with a resin, for example, it is useful for the production of a high-strength resin composite material, and so on, it can be supplied to a wide variety of industrial applications without deteriorating the functions inherent to nanocarbon.

10 Nanocarbon 20 having oxygen functional group in molecular skeleton 20 Amine 30 Ammonium ionic group 40 Amino group 100 Nanocarbon dispersion 200 having oxygen functional group in molecular skeleton 200 Amine dispersion 300 Obtained by adding dispersion 200 to dispersion 100 Amination reaction liquid 400 obtained by subjecting reaction liquid 300 to acid treatment, purification, and solvent dispersion, an organic solvent dispersion of graphene oxide obtained by removing ammonium ionic groups having amino groups

Claims (24)

1. Nanocarbon obtained by removing ammonium ionic group from nanocarbon having amino group in molecular skeleton
2. Nanocarbon with amino group in the molecular skeleton and no ammonium ion group
3. The nanocarbon according to any one of claims 1 to 2, wherein the nanocarbon having an amino group in the molecular skeleton is graphene oxide.
4. It comprises a step of removing an ammonium ionic group by allowing an amine dissolved in a solvent to act on a dispersion of nanocarbon having an oxygen functional group in the molecular skeleton, and subsequently causing an acid to act on the product. The method for producing nanocarbon according to any one of claims 1 to 3, wherein:
5. A dispersion obtained by dispersing the nanocarbon according to any one of claims 1 to 3 in an organic solvent.
6. It comprises a step of removing an ammonium ionic group by allowing an amine dissolved in a solvent to act on a dispersion of nanocarbon having an oxygen functional group in the molecular skeleton, and subsequently causing an acid to act on the product. A method for producing a dispersion according to claim 5
7. The nanocarbon according to any one of claims 1 to 3, wherein in the amine, the substituent on the nitrogen atom is a primary or secondary amine composed of a hydrocarbon group having 4 to 26 carbon atoms.
8. 5. The method for producing nanocarbon according to claim 4, wherein in the amine, the substituent on the nitrogen atom is a primary or secondary amine composed of a hydrocarbon group having 4 to 26 carbon atoms.
9. The nanocarbon dispersion liquid according to claim 5, wherein in the amine, the substituent on the nitrogen atom is a primary or secondary amine composed of a hydrocarbon group having 4 to 26 carbon atoms.
10. The method for producing a nanocarbon dispersion liquid according to claim 6, wherein in the amine, a substituent on a nitrogen atom is a primary or secondary amine composed of a hydrocarbon group having 4 to 26 carbon atoms.
11. The nanocarbon according to any one of claims 1 to 3, wherein in the amine, the substituent on the nitrogen atom has an unsaturated bond or an aromatic group in a part of its structure.
12. The method for producing nanocarbon according to claim 4, wherein in the amine, the substituent on the nitrogen atom has an unsaturated bond or an aromatic group in a part of its structure.
13. The nanocarbon dispersion liquid according to claim 5, wherein the substituent on the nitrogen atom in the amine has an unsaturated bond or an aromatic group in a part of its structure.
14. The method for producing a nanocarbon dispersion liquid according to claim 6, wherein the substituent on the nitrogen atom in the amine has an unsaturated bond or an aromatic group in a part of its structure.
15. The amine is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearylamine, N-methyloctadecylamine, The nanocarbon according to any one of claims 1 to 3, which is one or two or more amines selected from polyethylene glycol stearylamine.
16. The amine is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearylamine, N-methyloctadecylamine, 5. The method for producing nanocarbon according to claim 4, wherein the one or more amines selected from polyethylene glycol stearylamine are used.
17. The amine is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearylamine, N-methyloctadecylamine, The nanocarbon dispersion liquid according to claim 5, which is one or two or more amines selected from polyethylene glycol stearylamine.
18. The amine is butylamine, hexylamine, aniline, benzylamine, octylamine, phenethylamine, aminoadamantane, dodecylamine, tetradecylamine, hexadecylamine, oleylamine, 2-octyldodecylamine, stearylamine, N-methyloctadecylamine, The method for producing a nanocarbon dispersion liquid according to claim 6, which is one or two or more amines selected from polyethylene glycol stearylamine.
19. The nanocarbon dispersion liquid according to claim 5, wherein the organic solvent in which the nanocarbon is dispersed has a dielectric constant (ε) of 2 or more.
20. The method for producing a nanocarbon dispersion liquid according to claim 6, wherein the organic solvent in which the nanocarbon is dispersed has a dielectric constant (ε) of 2 or more.
21. 6. The nanocarbon dispersion liquid according to claim 5, wherein the viscosity (Pa · S) at 20 ° C. of the organic solvent in which the nanocarbon is dispersed is 1 × 10 ⁻⁴ or more.
22. The method for producing a nanocarbon dispersion liquid according to claim 6, wherein an organic solvent in which the nanocarbon is dispersed has a viscosity (Pa · S) at 20 ° C. of 1 × 10 ⁻⁴ or more.
23. The organic solvent in which the nanocarbon is dispersed is a saturated or unsaturated hydrocarbon solvent such as hexane, petroleum ether, toluene, xylene, light oil, polyolefin, 1-methoxy-2-propanol, ethanol, butanol, 2-ethylhexanol , Alcohol solvents containing polyhydric alcohols such as ethylene glycol and glycerin, ether solvents such as ethyl cellosolve, dimethoxyethane, tetrahydrofuran and cyclopentyl methyl ether, ethyl acetate, butyl acetate, 2-ethylhexyl acetate, methyl acrylate, methacryl Ester solvents such as methyl acid, halogen solvents such as dichloromethane and trichloroethylene, amide solvents such as formamide, dimethylformamide, and dimethylacetamide, acetone, methyl ethyl ketone, methyl isobutyl The nanocarbon dispersion liquid according to claim 5, which is a mixed solvent of one or two or more solvents selected from ketone solvents such as tilketone and cyclohexanone, and nitrile solvents such as acetonitrile and acrylonitrile.
24. The organic solvent in which the nanocarbon is dispersed is a saturated or unsaturated hydrocarbon solvent such as hexane, petroleum ether, toluene, xylene, light oil, polyolefin, 1-methoxy-2-propanol, ethanol, butanol, 2-ethylhexanol , Alcohol solvents containing polyhydric alcohols such as ethylene glycol and glycerin, ether solvents such as ethyl cellosolve, dimethoxyethane, tetrahydrofuran and cyclopentyl methyl ether, ethyl acetate, butyl acetate, 2-ethylhexyl acetate, methyl acrylate, methacryl Ester solvents such as methyl acid, halogen solvents such as dichloromethane and trichloroethylene, amide solvents such as formamide, dimethylformamide, and dimethylacetamide, acetone, methyl ethyl ketone, methyl isobutyl The method for producing a nanocarbon dispersion liquid according to claim 6, which is a mixed liquid of one or two or more solvents selected from ketone solvents such as tilketone and cyclohexanone, and nitrile solvents such as acetonitrile and acrylonitrile.

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