JP2017178770A - Method for producing graphite oxide derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a graphite oxide derivative that can simply produce a high-quality graphite oxide derivative.SOLUTION: The method for producing a graphite oxide derivative includes a step of oxidizing graphite and a step of reacting graphite oxide in a graphite oxide-containing composition produced in the oxidizing step with a compound reactive with an oxygen-containing functional group of the graphite oxide to produce a graphite oxide derivative and does not include a step of purifying the graphite oxide-containing composition and drying the same between the oxidizing step and the step of producing the graphite oxide derivative.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a graphite oxide derivative. More specifically, catalysts, battery and capacitor electrode active materials, thermoelectric conversion materials, conductive materials, luminescent materials, lubricant additives, polymer additives, permeable membrane materials, antibacterial materials, water repellent materials, adsorbent materials, etc. The present invention relates to a method for producing a graphite oxide derivative that can be suitably used as

Graphite oxide is obtained by oxidizing graphite with a layered structure in which carbon atoms bonded by sp ² bonds are arranged in a plane and adding oxygen-containing functional groups. Has been made. Graphite oxide is a catalyst, battery and capacitor electrode active materials, thermoelectric conversion materials, conductive materials, luminescent materials, lubricant additives, polymer additives, permeable membrane materials, antibacterial materials, water repellent materials, adsorbent materials, etc. It is expected to be used as

In order to further impart a desired function to such graphite oxide, a method of derivatizing graphite oxide can be considered. For example, it is desired that graphite oxide is used as a lubricating additive by being dispersed in oil, or combined with a polymer or other resin. Therefore, as it is, hydrophilic graphite oxide cannot be sufficiently dispersed in nonpolar, low polarity dispersion media (hydrophobic dispersion media) such as oil and resin. It is conceivable to reduce the contained functional group or to modify graphite oxide with a hydrophobic substituent. There have been reported examples of graphite oxide reduction reaction and substituent modification reaction so far (see Patent Documents 1 and 2 and Non-Patent Documents 1 to 3). Among them, Non-Patent Document 3 has been studied for the purpose of improving the dispersibility of graphite oxide in a non-polar dispersion medium, but actively removes reactive oxygen by purification and drying as a pretreatment and reduction treatment. In addition, treatment with a strongly basic reagent as pre-reaction treatment is performed.

By the way, as a method for producing graphite oxide, it is common to synthesize graphite oxide by reacting graphite with a strong oxidizing agent in an acid solvent, and then purify the generated graphite oxide from a solution. The Hummers method using sulfuric acid and potassium permanganate as agents is known (see Non-Patent Document 4 and Patent Documents 3 to 5). As other methods, a Brodie method using nitric acid and potassium chlorate, a Staudenmaier method using sulfuric acid, nitric acid and potassium chlorate as oxidizing agents, and the like are known. After oxidation of graphite, purification of graphite oxide from a reaction solution containing graphite oxide is generally performed by centrifugation or filtration of the reaction solution, but a method of performing filtration while applying pressure with gas is efficient. It has been reported as a simple method for purifying graphite oxide (see Non-Patent Documents 5 and 6).

Japanese Patent No. 5234325 Chinese Patent No. 10193530 JP 2002-53313 A JP 2011-148701 A Japanese Patent No. 4798411

Yuta Nishina, "Development of surface modification technology for graphene oxide", Interdisciplinary report on new academic research "Atomic Layer Science" (2014) Open call for research synthesis group, 71-74 Daniel R. Dreyer, et.al, “Reduction of graphite oxide using alcohols” J. Mater. Chem., 2011, 21, 3443-3447 Jean-Philippe, et.al, Langmuir, 2012, 28.6691-6697 William S. Hummers, et.al, Journal of American Chemical Society, 1958, 80, 1339 Gabriel Ceriotti, et.al, RSC Advances, 2015, 5, 50365 Gabriel Ceriotti, et.al, Nanoscale, 2015, 00, SI, pp.1-8

As described above, various methods are known as a method for producing graphite oxide. However, in any of these methods, when graphite is oxidized and then graphite oxide is separated from the reaction liquid containing graphite oxide, repeated centrifugation is time-consuming and increases the amount of waste liquid. End up. In addition, if the purification proceeds to a certain degree of purification, which will be described later, the filter may be clogged when the reaction solution is filtered even under pressure, which may hinder the efficient production of graphite oxide and its derivatives. It has become. At present, it is almost impossible to produce graphite oxide and its derivatives on an industrial scale.

This invention is made | formed in view of the said present condition, and aims at providing the manufacturing method of the graphite oxide derivative which makes it possible to manufacture a high quality graphite oxide derivative simply.

The present inventors have studied various methods for efficiently producing high-quality graphite oxide derivatives, omitting at least one of purification and drying of the graphite oxide-containing composition obtained in the oxidation step, and performing unpurified and / or unrefined. A graphite oxide derivative was prepared using dry graphite oxide. And this manufacturing method of graphite oxide derivative makes the manufacturing process drastically simple, and there is a merit in the process, and a high quality graphite oxide derivative in which a group having a desired functional group is sufficiently introduced is obtained. I found out that I was able to solve the above problems. The present inventors further obtain a graphite oxide derivative having sufficiently reduced (disappeared) drop sensitivity by derivatizing graphite oxide under high temperature conditions in such a method for producing a graphite oxide derivative. It has also been found that this is possible, and the present invention has been achieved.

That is, the present invention is a method for producing a graphite oxide derivative, which comprises a step of oxidizing graphite, graphite oxide in a graphite oxide-containing composition obtained in the oxidation step, and oxygen in the graphite oxide. A step of obtaining a graphite oxide derivative by reacting a compound that reacts with the contained functional group, and a step of purifying and drying the graphite oxide-containing composition between the oxidation step and the step of obtaining the graphite oxide derivative. It is a manufacturing method of the graphite oxide derivative characterized by not containing.
The present invention is also a graphite oxide derivative having an alkyl group and having a grade of 8 grade as measured by a drop sensitivity test defined in JIS K 4810.

By the method for producing a graphite oxide derivative of the present invention, a high quality graphite oxide derivative can be easily obtained.

4 is an FT-IR chart of graphite oxide produced in Preparation Example 2. 2 is an FT-IR chart of graphite oxide derivative A produced in Example 1. FIG. 2 is an XRD chart of graphite oxide derivative A produced in Example 1. FIG. 4 is an FT-IR chart of graphite oxide derivative B produced in Example 2. FIG. 4 is an FT-IR chart of graphite oxide derivative C produced in Example 3. FIG. 6 is an FT-IR chart of graphite oxide derivative D produced in Example 4. 6 is an FT-IR chart of graphite oxide derivative E produced in Example 5. FIG. 6 is an XRD chart of graphite oxide derivative E produced in Example 5. 6 is an FT-IR chart of graphite oxide derivative F produced in Example 6. FIG. 6 is an FT-IR chart of graphite oxide derivative G produced in Example 7. FIG. 6 is an FT-IR chart of graphite oxide derivative H produced in Example 8. 6 is an FT-IR chart of graphite oxide derivative I produced in Example 9. 6 is an XRD chart of graphite oxide derivative I produced in Example 9. 4 is an FT-IR chart of graphite oxide derivative J produced in Example 10. FIG. 10 is an XRD chart of graphite oxide derivative J produced in Example 10. 4 is an FT-IR chart of graphite oxide derivative K produced in Comparative Example 1. 6 is an FT-IR chart of graphite oxide derivative L produced in Comparative Example 2.

The present invention is described in detail below.
In addition, the form which combined two or more each preferable characteristic of this invention described separately in a paragraph below is also a preferable form of this invention.

In addition, as described in Non-Patent Document 3, when oxygen oxide is purified and dried, reduction treatment, treatment with a strongly basic reagent as pre-reaction treatment, etc., reactive oxygen is removed from the graphite oxide. Therefore, it is considered that sufficient modification reaction does not proceed and the dispersibility is poor. On the other hand, using the method of the present invention, it was found that a graphite oxide derivative with good dispersibility can be obtained even in ethanol or decane, which was not sufficiently dispersible with the graphite oxide derivative obtained by the method described in Non-Patent Document 3. It was.
Moreover, when a cation of a cationic organic compound is used as a pretreatment as described in Patent Document 1, a portion derived from the cation is then strongly bonded to the graphite oxide derivative as an impurity, and it becomes difficult to remove.

(Graphite oxide derivative)
Graphite oxide is oxygen bonded by oxidizing graphitic carbon materials such as graphene and graphite (graphite), and the oxygen is a carboxyl group, a carbonyl group, a hydroxyl group, an epoxy with respect to the graphite carbon material. It exists as a substituent such as a group. The graphite oxide derivative of the present invention further has a structure in which a functional group having a group derived from a compound that reacts with an oxygen-containing functional group of graphite oxide is bonded to a carbon atom of graphite oxide.
The graphite oxide derivative may further have a functional group such as a sulfur-containing group or a nitrogen-containing group, but is composed of only carbon, hydrogen, and oxygen as constituent elements, or carbon, It is more preferable that only hydrogen, oxygen, and nitrogen are constituent elements. Preferred examples of the graphite oxide derivative will be described later.

Examples of the analysis showing the characteristics of the graphite oxide derivative obtained by the production method of the present invention include mass spectrometry and FT-IR method. Fragments ionized by mass spectrometry can be easily observed. Since graphite oxide itself has a large mass, ions are not detected by mass spectrometry, that is, only a site derived from a compound introduced into graphite oxide is observed.
In the FT-IR method, for example, when the graphite oxide derivative has a hydrocarbon group at the end, the graphite oxide derivative of the present invention has a C—H peak (near 2900 cm ⁻¹⁾ derived from the hydrocarbon group. ) Can be easily analyzed.

First, in the method for producing a graphite oxide derivative of the present invention, the step of purifying and drying the graphite oxide-containing composition between the step of oxidizing graphite and the step of obtaining the graphite oxide derivative and the concentration step are described in order. To do. Next, the step of oxidizing graphite and the step of obtaining a graphite oxide derivative will be described in order.

(The production method of the present invention does not include a step of purifying and drying the graphite oxide-containing composition)
The production method of the present invention does not include a step of purifying and drying a graphite oxide-containing composition between the oxidation step and the step of obtaining a graphite oxide derivative. That is, the production method of the present invention may be one in which the graphite oxide-containing composition is not purified and not dried between the oxidation step and the step of obtaining the graphite oxide derivative. And only one of drying and drying may be performed. In addition, the above-mentioned “excluding the step of purifying and drying a graphite oxide-containing composition” means that the graphite oxide-containing composition is used when the graphite oxide-containing composition is subjected to a reaction in a step of obtaining a graphite oxide derivative. Means that the product is not purified and dried. The present inventors have found that the reactive oxygen-containing functional group possessed by graphite oxide is reduced and / or inactivated during the purification step and drying step of graphite oxide from the graphite oxide-containing composition, By omitting at least one of refining and drying, graphite oxide in a composition containing graphite oxide with a sufficient number of reactive oxygen-containing functional groups is applied to the reaction (modification reaction) in the process of obtaining a graphite oxide derivative. Found that you can. As a result, it is possible to efficiently obtain a high-quality graphite oxide derivative in which a group having a desired functional group is sufficiently introduced by a modification reaction. Moreover, since at least one of refining and drying is omitted, the production process becomes simpler, and there is a merit on the process.

In the present specification, the step of purifying the graphite oxide-containing composition refers to solid impurities (for example, an oxidizing agent such as permanganate) from the graphite oxide-containing composition and / or a solvent (such as sulfuric acid) during the oxidation reaction. The graphite oxide-containing composition is made into a graphite oxide aqueous dispersion.
The role and significance of purification include, for example, obtaining graphite oxide or a graphite oxide water dispersion by setting the sulfuric acid concentration in the graphite oxide-containing composition to 1% by mass or less, and graphite oxide or graphite oxide water. When the dispersion is diluted in water as described in Patent Document 5 (for example, when a 1-10% graphite oxide aqueous dispersion is used), the total ion concentration (mostly sulfuric acid concentration) is the threshold described in Patent Document 5 It is known that the graphite oxide itself is ionized below the concentration, and the interaction with water molecules becomes stronger and the dispersibility of graphite oxide is dramatically improved. Moreover, if refinement | purification progresses to this level, filterability will become very bad by the dispersibility. It has also been found that when graphite oxide is used as a material, this dispersibility greatly affects the physical properties. That is, in order to fully exhibit the physical properties of graphite oxide alone, the purification step is essential, and many studies have been made. However, the graphite oxide itself is not applied to the material as in the present invention. When a chemical reaction such as modification is performed and a derivative is applied as the material, the reactivity of the graphite oxide itself is more important than the dispersibility of the graphite oxide. It becomes. When the total ion concentration (sulfuric acid concentration) as described in Patent Document 5 is ionized, the present inventors ionize or decompose highly active oxygen substituents, which is disadvantageous in the subsequent modification reaction. I found out that In the present invention, only the step of separating the graphite oxide-containing composition having an appropriate sulfuric acid concentration from the reaction solution after the oxidation step can be performed, but it is preferable not to perform a more sophisticated purification step. That is, it can be said that the advanced purification process that can be omitted in the present invention is to reduce acidity, promote ionization of graphite oxide, and impart strong dispersibility to water, as described in Patent Document 5. That is, the purification step that can be omitted in the present invention is a step of making sulfuric acid less than 1% by mass with respect to the mass of graphite oxide.
When performing the step of separating the graphite oxide-containing composition, the separation step is performed in a later stage as described later from the reaction composition to the extent that it does not correspond to the step of purifying and drying the reaction composition containing graphite oxide. What is necessary is just to isolate | separate a graphite oxide containing composition so that it may be suitable for the reaction process, and uses 1 type (s) or 2 or more types of methods, such as washing and centrifugation after dissolving a solid impurity in water, and filtration. In addition, a flocculant such as a surfactant or an organic solvent may be added during filtration as described later. Further, the separation step may be performed in air or in an inert gas atmosphere such as nitrogen, helium, or argon. Moreover, when performing a separation process, you may remove some solvents, such as a sulfuric acid and water.

In particular, the production method of the present invention preferably does not include a step of purifying the graphite oxide-containing composition between the oxidation step and the step of obtaining the graphite oxide derivative. As a result, it is possible to use graphite oxide in which the number of reactive oxygen-containing functional groups is more sufficiently maintained for the modification reaction, and the resulting graphite oxide derivative is more sufficiently introduced with a group having a desired functional group. High quality. Furthermore, the production method of the present invention becomes very simple.
That is, one preferable embodiment of the production method of the present invention is a method of producing a graphite oxide derivative, and the production method includes a step of oxidizing graphite and a graphite oxide-containing composition obtained in the oxidation step. And a step of obtaining a graphite oxide derivative by reacting a compound that reacts with an oxygen-containing functional group of the graphite oxide to obtain a graphite oxide-containing composition between the oxidation step and the step of obtaining the graphite oxide derivative. The step of purifying the graphite oxide-containing composition without the step of purifying the product is a step of reducing the sulfuric acid to less than 1% by mass with respect to the mass of the graphite oxide contained in the graphite oxide-containing composition. This is a method for producing a graphite derivative.

Moreover, the process of drying a graphite oxide containing composition means the process of removing volatile solvents, such as water used in the oxidation process at least from the graphite oxide containing composition, and making it a dried material.
Further, the present inventors can remove even the water coordinated to the highly active oxygen functional group of graphite oxide when the water concentration relative to the graphite oxide in the graphite oxide-containing composition is at least 3% by mass. As a result, it was found that the oxygen functional group, which was stable in coordination, was eliminated, which was disadvantageous in the subsequent modification reaction. That is, by using a graphite oxide-containing composition containing 3% by mass or more of water with respect to graphite oxide, an active oxygen functional group superior in modification reaction can be stably maintained. That is, the drying step that can be omitted in the present invention is a step of making water less than 3% by mass with respect to the mass of graphite oxide.
When performing the step of drying the graphite oxide-containing composition, the drying step can be performed using one or two or more methods such as centrifugation, filtration, evaporation, and the like during the filtration, An aggregating agent such as an organic solvent may be added.
The evaporation can be performed, for example, under reduced pressure or under heating, but is preferably performed under reduced pressure and under heating. Centrifugation and filtration may be performed in air or in an inert gas atmosphere such as nitrogen, helium, or argon.

One preferred embodiment of the production method of the present invention is, for example, a method for producing a graphite oxide derivative, which comprises a step of oxidizing graphite and a graphite oxide-containing composition obtained in the oxidation step. Graphite oxide contained therein, and a step of reacting a compound that reacts with the oxygen-containing functional group of the graphite oxide to obtain a graphite oxide derivative, wherein the graphite oxide containing step is performed between the oxidation step and the step of obtaining the graphite oxide derivative. A manufacturing method that does not include a step of drying the composition, wherein the step of drying the graphite oxide-containing composition comprises less than 3% by weight of water with respect to the mass of the graphite oxide contained in the graphite oxide-containing composition. It may be a process for producing a graphite oxide derivative.
In particular, the production method of the present invention is preferably one in which neither the purification step of the graphite oxide-containing composition nor the drying step is performed. Thereby, the effect of this invention which can obtain a high quality graphite oxide derivative simply becomes remarkable.
That is, one preferable embodiment of the production method of the present invention includes a step of oxidizing graphite (oxidation step), graphite oxide in the graphite oxide-containing composition obtained in the oxidation step, and oxygen content of the graphite oxide. A step of obtaining a graphite oxide derivative by reacting a compound that reacts with a functional group, and a step of purifying the graphite oxide-containing composition between the oxidation step and the step of obtaining the graphite oxide derivative; And a step of purifying the graphite oxide-containing composition comprising sulfuric acid with respect to the mass of the graphite oxide contained in the graphite oxide-containing composition. And the step of drying the graphite oxide-containing composition is a step of reducing water to less than 3% by mass with respect to the mass of graphite oxide contained in the graphite oxide-containing composition. Of graphite oxide derivatives It is the law.

(Concentration of graphite oxide-containing composition)
It is preferable that the manufacturing method of this invention includes the process (concentration process) which removes a part of sulfuric acid and a solvent from a reaction composition. More preferably, the production method of the present invention includes a step of concentrating the graphite oxide-containing composition between the oxidation step and the step of obtaining the graphite oxide derivative. The concentration step in the present invention is a step of obtaining a graphite oxide-containing composition by removing a part of sulfuric acid and water from the reaction composition, and the composition contains 1% by mass of sulfuric acid with respect to the mass of graphite oxide. It means a step of remaining above and / or leaving 3% by mass or more of water with respect to the mass of graphite oxide. For example, in the reaction composition immediately after the oxidation step, when the acid is excessively present relative to the amount of the raw material compound in the step of obtaining the graphite oxide derivative, the acid relative to the amount of the raw material compound is appropriately removed by the concentration step. The amount of can be adjusted within a suitable range described later, and the modification reaction can proceed with higher efficiency.

For example, the graphite oxide-containing composition subjected to the reaction in the step of obtaining the graphite oxide derivative separated through the concentration step or the like is 3 to 10000 mass of water with respect to 100 mass% of the graphite oxide in the composition. % Is preferable. When the water content is 3% by mass or more, active oxygen functional groups can be coordinated and stabilized, and the subsequent modification reaction can be efficiently reacted. Moreover, it can prevent water from interfering with modification reaction by setting it as 10000 mass% or less.
The content is more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 50% by mass or more. The content is more preferably 5000% by mass or less, still more preferably 3000% by mass or less, still more preferably 2000% by mass or less, and particularly preferably 1000% by mass or less. Most preferably, it is 500 mass% or less.

In general, an acid is present in excess of graphite oxide immediately after the oxidation step (for example, about 2000 to 5000% by mass of sulfuric acid with respect to 100% by mass of graphite oxide). Excessive with respect to graphite (for example, about 500 to 10,000% by mass with respect to 100% by mass of graphite oxide).
It is preferable to concentrate the acid and water in the concentration step so that the amount of water falls within the above range. Thereby, reactive oxygen can exist stably until the process of obtaining a graphite oxide derivative, and can be efficiently used for the modification reaction.

Moreover, when using a permanganate as an oxidizing agent in an oxidation process so that it may mention later, the graphite oxide containing composition after a concentration process may contain 0.01 mass% or more of manganese in the composition.
Furthermore, as described later, when potassium permanganate is used as an oxidizing agent in the oxidation step, the graphite oxide-containing composition after the concentration step may contain 0.01% by mass or more of potassium in the composition.

The concentration step in the present invention is to adjust the amount of water or the like in the graphite oxide-containing composition. In this step, unless the amount of water is less than the lower limit described above, centrifugal separation, water, etc. are added to redisperse, filter, and agglomerate. It can carry out using methods, such as filtration using an agent, and vacuum concentration. Moreover, although these processes may be repeated, it is preferable to complete by one process, without repeating. Furthermore, there is no particular limitation on the flocculant in the case of concentrating with the flocculant, but those that do not interfere with the subsequent modification reaction are preferred. Examples of the flocculant include polymeric flocculants that do not react with oxygen functional groups and sulfuric acid of graphite oxide, and volatile flocculants that can be easily removed at the reaction temperature during the reaction.

(Process of oxidizing graphite)
The step of oxidizing the graphite is not particularly limited as long as the graphite is oxidized, and any method such as the above-described Hummers method, Brodie method, or Staudenmaier method may be used. It may be a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, which employs the oxidation method in the Hummers method, as in the method described in the examples described later.

In the production method of the present invention, it is preferable that the oxidation step oxidizes graphite using an acid.
When the oxidation step oxidizes graphite using an acid, the production method of the present invention is used for the step of obtaining a graphite oxide derivative in order to omit at least one of purification and drying of the graphite oxide-containing composition obtained in the oxidation step. The acid remains in the graphite oxide-containing composition to be formed, and the acid stabilizes the oxygen functional group contained in the graphite oxide. In this case, the components derived from the oxidizing agent used in the oxidation step, water used in the oxidation step and reaction stop step, etc. remain in the graphite oxide-containing composition used in the step of obtaining the graphite oxide derivative. The modification reaction can proceed with high efficiency. As a result, in the step of obtaining the graphite oxide derivative, it is possible to use it for the modification reaction while stably presenting the oxygen functional group contained in the graphite oxide, and the production method of the present invention is simpler and more efficient. can do.

Especially, it is one of the suitable embodiment of this invention that the said oxidation process is a process of adding permanganate to the liquid mixture containing graphite and a sulfuric acid.
When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, the amount of sulfuric acid used is such that the mass ratio of sulfuric acid to graphite (sulfuric acid / graphite) is 25-60. Preferably there is. When the mass ratio is 25 or more, graphite oxide can be efficiently produced by sufficiently preventing the reaction solution (mixed solution) from becoming highly viscous during the oxidation reaction. Further, when the mass ratio is 60 or less, the amount of waste liquid can be sufficiently reduced.
The mass ratio is more preferably 26 or more, further preferably 27 or more, and particularly preferably 28 or more. The mass ratio is more preferably 54 or less, still more preferably 48 or less, and particularly preferably 42 or less.

The graphite used in the oxidation step preferably has an average particle size of 3 μm or more and 80 μm or less. By using a material having such an average particle size, the oxidation reaction can be advanced more efficiently. The average particle diameter of graphite is more preferably 3.2 μm or more and 70 μm or less.
The average particle diameter can be measured by a particle size distribution measuring device.

The shape of the graphite used for the oxidation step is not particularly limited, and examples thereof include fine powder, powder, granule, granule, scale, polyhedron, rod, and curved surface-containing shape. In addition, the particles having the average particle diameter in the above range are produced by, for example, a method of pulverizing the particles with a pulverizer, a method of selecting the particle diameter by sieving the particles, a combination of these methods, or the like. It is possible to manufacture by optimizing the preparation conditions at the stage of obtaining and obtaining particles having a desired particle diameter.

The graphite content in the mixed solution containing graphite and sulfuric acid is preferably 0.5% by mass or more, more preferably 1% by mass or more, with respect to 100% by mass of the mixed solution. The content is more preferably 5% by mass or more, and particularly preferably 2% by mass or more. The graphite content is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 7% by mass or less, and particularly preferably 6% by mass or less.
Only one type of graphite may be used in the oxidation step in the production method of the present invention, or two or more types different in any of the average particle diameter, shape, and the like may be used.

When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, the permanganate added in the oxidation step includes sodium permanganate, potassium permanganate, permanganate. Ammonium acid, silver permanganate, zinc permanganate, magnesium permanganate, calcium permanganate, barium permanganate, and the like can be used, and one or more of these can be used, among which sodium permanganate , Potassium permanganate is preferred, and potassium permanganate is more preferred.

When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, the total amount of the permanganate added in the oxidation step is 100% by mass of graphite in the mixed solution. It is preferable that it is 50-500 mass% with respect to. Thereby, graphite oxide can be manufactured safely and efficiently. In addition, the amount of oxygen atoms introduced into the graphite oxide can be adjusted by changing the total amount of the oxidizing agent added.
The total addition amount is more preferably 100% by mass or more, further preferably 150% by mass or more, further preferably 200% by mass or more, and particularly preferably 240% by mass or more. Further, the total addition amount is more preferably 450% by mass or less, further preferably 400% by mass or less, further preferably 350% by mass or less, and particularly preferably 300% by mass or less. preferable.

When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, in the oxidation step, the permanganate may be added all at once or added in multiple times. Alternatively, it may be added continuously, but it is preferable to add in multiple portions or add continuously. Thereby, it is possible to control the reaction more easily by suppressing the rapid progress of the oxidation reaction. When the permanganate is added in a plurality of times, the number of times of addition is preferably 3 times or more, more preferably 5 times or more, further preferably 7 times or more, 9 times The above is particularly preferable.
When the permanganate is added in a plurality of times, the amount added per time may be the same or different.

When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, in the oxidation step, permanganic acid while maintaining the temperature of the mixed solution within a range of 10 to 50 ° C. It is preferred to add a salt. By maintaining in such a temperature range, it is possible to sufficiently proceed while controlling the oxidation reaction.
The temperature is preferably maintained at 12 ° C or higher, more preferably maintained at 15 ° C or higher, further preferably maintained at 18 ° C or higher, and particularly preferably maintained at 20 ° C or higher.

When the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, the oxidation step adds permanganate while maintaining the temperature change of the mixed solution at 25 ° C. or less. It is preferable that it is a process to perform. Thereby, an oxidation process can be performed more stably.
In the oxidation step, the temperature change is more preferably maintained at 20 ° C. or less, further preferably maintained at 15 ° C. or less, and particularly preferably maintained at 10 ° C. or less.

In the case where the oxidation step is a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, in the oxidation step, the permanganate is added for 10 minutes to 10 hours from the viewpoint of performing the oxidation step stably. It is preferable to add over the period. More preferably, the permanganate is added over 30 minutes or more, more preferably over 1 hour or more, particularly preferably over 2 hours or more. It is.
From the viewpoint of efficiently producing graphite oxide, the addition time of the permanganate is preferably 8 hours or less, more preferably 7 hours or less, and even more preferably 6 hours or less. .

The oxidation step is preferably performed while stirring using a known stirrer or the like.
The oxidation step can be performed, for example, in air or in an inert gas atmosphere such as nitrogen, helium, or argon. Moreover, although the said pressure process does not specifically limit the said oxidation process, For example, it is preferable to carry out on normal-pressure conditions.
The time for the oxidation step is preferably 0.5 to 120 hours, more preferably 1 to 15 hours, and still more preferably 2 to 10 hours.
The oxidation step may be performed continuously or intermittently.

The liquid mixture can be obtained by mixing graphite, sulfuric acid, and other components as required. The mixing can be appropriately performed by a known method. For example, it is preferable to uniformly disperse graphite by performing ultrasonic treatment or using a known disperser.

The method for producing a graphite oxide derivative of the present invention includes a step of oxidizing graphite and a step of obtaining a graphite oxide derivative described later, and does not include a step of purifying and drying the graphite oxide-containing composition between both steps. As long as it includes other steps such as an aging step and an oxidation reaction stop (quenching) step.

In the aging step, the temperature and time for aging the reaction solution obtained in the oxidation step may be appropriately selected, but the reaction solution is preferably maintained at a temperature of 0 to 90 ° C, more preferably 20 to 80. To maintain a temperature of ℃.
The aging time is preferably 0.1 to 24 hours. More preferably, it is 0.5 to 5 hours.

The oxidation reaction stopping step may be performed in air or in an inert gas atmosphere such as nitrogen, helium, or argon. Moreover, you may carry out in a vacuum.
The oxidation reaction stopping step can be performed, for example, by setting the temperature of the reaction solution to 5 to 15 ° C., adding water to the reaction solution, and then adding hydrogen peroxide as a reducing agent. Moreover, you may carry out by adding a reaction liquid to the water or hydrogen peroxide water set to 5-25 degreeC.
The time for the oxidation reaction stopping step can be, for example, 0.01 to 5 hours.

(Step of obtaining graphite oxide derivative)
In the production method of the present invention, a graphite oxide derivative is obtained by reacting graphite oxide in the graphite oxide-containing composition obtained in the oxidation step with a compound that reacts with the oxygen-containing functional group of the graphite oxide. The compound that reacts with the oxygen-containing functional group of graphite oxide is preferably at least one selected from the group consisting of alcohol, silane compound, fatty acid (salt), fatty acid ester, isocyanate compound, and amine, for example. Of these, alcohol and / or amine are more preferable. The silane compound preferably has a siloxy group and / or an alkoxy group directly bonded to a silicon atom from the viewpoint of improving the reactivity with the oxygen-containing functional group of graphite oxide. In addition, the production | generation of a graphite oxide derivative is confirmed by measuring an infrared absorption spectrum along the method of an Example.

The compound that reacts with the oxygen-containing functional group of graphite oxide preferably has a hydrocarbon group from the viewpoint of further improving the dispersibility of the graphite oxide derivative in the nonpolar dispersion medium. The hydrocarbon group preferably has 5 or more carbon atoms, more preferably 6 or more, still more preferably 7 or more, and particularly preferably 8 or more. The hydrocarbon group has a sufficiently high dispersion rate in the non-polar dispersion medium of the graphite oxide derivative, and has a carbon number of 50 or less from the viewpoint of suitably producing the graphite oxide derivative. Is preferably 36 or less, more preferably 24 or less.

The hydrocarbon group is preferably linear. When the hydrocarbon group is a straight chain, the straight chain hydrocarbon group is easily introduced into the graphite oxide, so that the production method of the present invention becomes more efficient.

It is also preferred that the hydrocarbon group is a branched chain. When the hydrocarbon group is a branched chain, the dispersibility of the graphite oxide derivative in the nonpolar dispersion medium is further improved. Further, the compound as a raw material tends to become liquid at room temperature (25 ° C.), and in that case, handling at the time of producing the derivative is easy.

In the step of obtaining the graphite oxide derivative, the reaction in which the graphite oxide is modified by reacting with a compound that reacts with the oxygen-containing functional group of the graphite oxide and the reduction reaction of the graphite oxide itself simultaneously compete and reduce. From the viewpoint of promoting the reaction for modifying graphite oxide by sufficiently suppressing the reaction, the compound that reacts with the oxygen-containing functional group of the graphite oxide is preferably an alcohol and / or an amine. More preferably, the alcohol is an aliphatic alcohol. The amine is more preferably an aliphatic amine.

Examples of the aliphatic alcohol include n-octyl alcohol, sec-octyl alcohol, n-nonyl alcohol, sec-nonyl alcohol, n-decyl alcohol, sec-decyl alcohol, n-undecyl alcohol, and sec-undecyl alcohol. , N-dodecyl alcohol, sec-dodecyl alcohol, n-tridecyl alcohol, sec-tridecyl alcohol, n-tetradecyl alcohol, sec-tetradecyl alcohol, n-hexadecyl alcohol, sec-hexadecyl alcohol, n-octadecyl Alcohol, sec-octadecyl alcohol, n-eicosyl alcohol, sec-eicosyl alcohol, 2-octyldodecyl alcohol, n-docosyl alcohol, sec-docosyl alcohol 2-octyltetradecyl alcohol, n-tetracosyl alcohol, sec-tetracosyl alcohol, 2-octylhexadecyl alcohol, n-hexacosyl alcohol, sec-hexacosyl alcohol, n-octacosyl alcohol, sec-octacosyl alcohol, n-triacontyl alcohol, sec-triacontyl alcohol, n-dotriacontyl alcohol, sec-dotriacontyl alcohol, n-tetratriacontyl alcohol, sec-tetratriacon Examples include chill alcohol, n-hexatriacontyl alcohol, sec-hexatriacontyl alcohol, and the like, and one or more of these can be used. Moreover, when using 2 or more types of aliphatic alcohol, you may use the mixture of these aliphatic alcohol.

Examples of the aliphatic amine include n-octylamine, sec-octylamine, n-nonylamine, sec-nonylamine, n-decylamine, sec-decylamine, n-undecylamine, sec-undecylamine, and n-dodecyl. Amine, sec-dodecylamine, n-tridecylamine, sec-tridecylamine, n-tetradecylamine, sec-tetradecylamine, n-hexadecylamine, sec-hexadecylamine, n-octadecylamine (stearylamine) ), Sec-octadecylamine, n-eicosylamine, sec-eicosylamine, 2-octyldodecylamine, n-docosylamine, sec-docosylamine, 2-octyltetradecylamine, n-tetracosylamine, sec-tetracosylamine Ruamine, 2-octylhexadecylamine, n-hexacosylamine, sec-hexacosylamine, n-octacosylamine, sec-octacosylamine, n-triacontylamine, sec-triacontylamine, n-detriaconti Ruamine, sec-dotriacontylamine, n-tetratriacontylamine, sec-tetratriacontylamine, n-hexatriacontylamine, sec-hexatriacontylamine, and the like. Can be used. Moreover, when using 2 or more types of aliphatic amines, you may use the mixture of these aliphatic amines.

In the step of obtaining the graphite oxide derivative, a compound that reacts with the oxygen-containing functional group of graphite oxide in the graphite oxide-containing composition (particularly preferably, the graphite oxide-containing composition after the concentration step) obtained in the oxidation step; If necessary, other components (for example, a solvent) can be mixed to obtain a mixed solution. The mixing can be appropriately performed by a known method, but it is preferable to uniformly disperse graphite oxide by, for example, performing ultrasonic treatment or using a known disperser.

The amount of the compound that reacts with the oxygen-containing functional group of graphite oxide is preferably 300 to 10,000% by mass with respect to 100% by mass of graphite oxide in the mixed solution. By using a compound that reacts with the oxygen-containing functional group of the graphite oxide in a large excess, the graphite oxide derivative can be produced efficiently. Thereby, the reduction reaction can be suppressed and the modification reaction of graphite oxide can be promoted.
The amount used is more preferably 350% by mass or more, still more preferably 400% by mass or more, still more preferably 450% by mass or more, and particularly preferably 500% by mass or more. Further, the amount used is more preferably 8000% by mass or less, further preferably 6000% by mass or less, further preferably 3000% by mass or less, and particularly preferably 1000% by mass or less. .

In the reaction of graphite oxide with a compound that reacts with the oxygen-containing functional group of graphite oxide, a known catalyst or the like can be applied. As a preferred embodiment of the present invention, as a catalyst, an acid catalyst such as sulfuric acid, an alkali metal A base catalyst such as hydroxide, amine, pyridine or the like can be used. When the compound that reacts with the oxygen-containing functional group of graphite oxide is an amine, the amine itself can be used as a catalyst.

When the compound that reacts with the oxygen-containing functional group of graphite oxide is a compound other than an amine and an acid catalyst is used as a catalyst in the process of obtaining a graphite oxide derivative, such as a compound that reacts with the oxygen-containing functional group of graphite oxide or graphite oxide By adjusting the amount of the acid catalyst with respect to the amount of the reaction raw material within a suitable range, the modification reaction can proceed more efficiently.
The preferable content of the acid catalyst with respect to 100% by mass of graphite oxide in the graphite oxide-containing composition provided for the step of obtaining the graphite oxide derivative is, for example, 0.01 to 1000% by mass. When the content of the acid catalyst is 0.01% by mass or more, the modification reaction can proceed efficiently. Further, when the content is 1000% by mass or less, the amount of waste (amount of waste liquid) can be sufficiently reduced and the modification reaction can be efficiently advanced. Here, as the acid catalyst, an acid residue such as sulfuric acid used in the oxidation step can be effectively used.
The content is more preferably 0.1% by mass or more, further preferably 1% by mass or more, further preferably 10% by mass or more, and further more preferably 20% by mass or more. Preferably, it is still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, the content is more preferably 700% by mass or less, further preferably 500% by mass or less, and further preferably 200% by mass or less.
For example, when the acid of the acid catalyst is sulfuric acid, the graphite oxide-containing composition used for the reaction in the step of obtaining a graphite oxide derivative is 1 mass of sulfuric acid with respect to 100 mass% of the mass of graphite oxide in the composition. % To 1000% by mass is preferable.

In addition, when the compound that reacts with the oxygen-containing functional group of graphite oxide is a compound other than an amine, and an acid catalyst is used as a catalyst in the step of obtaining a graphite oxide derivative, the graphite oxide contained in the reaction of the step of obtaining the graphite oxide derivative The composition preferably contains an acid catalyst in an amount of 0.1% by mass or more and 50% by mass or less based on 100% by mass of the compound that reacts with the oxygen-containing functional group of graphite oxide in the composition. By including the acid catalyst in an amount of 0.1% by mass or more, the modification reaction can proceed more efficiently. Moreover, the side reaction resulting from an acid catalyst can fully be suppressed by containing an acid catalyst 50 mass% or less. The content of the acid catalyst is more preferably 0.5% by mass or more. Further, the content of the acid catalyst is more preferably 20% by mass or less.
When the compound that reacts with the oxygen-containing functional group of graphite oxide is a compound other than an amine, graphite oxide is essentially an acidic substance, and the reaction proceeds autocatalytically. Although it is preferable to use a catalyst as described above, it is possible to allow the reaction to proceed autocatalytically without using a catalyst.

When a base catalyst (including amine) is used as a catalyst in the step of obtaining a graphite oxide derivative, the amount of the base catalyst with respect to the amount of the reaction raw material such as graphite oxide or a compound that reacts with the oxygen-containing functional group of graphite oxide is preferably within By adjusting inward, the modification reaction can proceed more efficiently. In the graphite oxide-containing composition provided for the step of obtaining the graphite oxide derivative, the preferable content of the base catalyst with respect to 100% by mass of the graphite oxide is the mass of the graphite oxide in the graphite oxide-containing composition after the concentration step described above. This is the same as the preferred acid content relative to 100% by mass.
For example, when the base is an alkali metal hydroxide and an amine, the graphite oxide-containing composition subjected to the reaction in the step of obtaining a graphite oxide derivative is an alkali with respect to 100% by mass of the graphite oxide in the composition. It is preferable to contain 1% by mass or more and 1000% by mass or less of metal hydroxide and amine. In addition, since a base catalyst neutralizes with the acid component in a graphite oxide containing composition, it is preferable that the quantity of the part except the neutralized part corresponds to the said range among the used base catalysts.

The reaction temperature in the step of obtaining the graphite oxide derivative is not particularly limited as long as the reaction proceeds. For example, it is preferably 120 ° C. or higher. By setting the reaction temperature to 120 ° C. or higher, the reduction reaction can be sufficiently suppressed and the modification reaction can proceed preferentially. Further, since oxygen is easily desorbed, the sensitivity is reduced (disappeared) by the sensitivity test. It is also advantageous to make it. Thus, from the viewpoint of allowing the modification reaction to proceed more efficiently and reducing (disappearing) the sensitivity of dropping, the reaction temperature is more preferably 130 ° C. or higher, and still more preferably 140 ° C. or higher. 150 ° C. or higher is particularly preferable.
From the viewpoint of suppressing side reactions, the reaction temperature is preferably 200 ° C. or lower.

For example, the present invention relates to a method for producing a graphite oxide derivative, which has a functional group having a hydrocarbon group by reacting graphite oxide with an alcohol and / or an amine at a reaction temperature of 120 ° C. or higher. It is also a method for producing a graphite oxide derivative including a step of obtaining a graphite oxide derivative. In this case, the graphite oxide may be obtained by purifying and drying the graphite oxide-containing composition obtained in the above oxidation step, but it may be obtained by omitting at least one of purification and drying. Preferably, it is more preferable to omit purification. By the above production method, the reduction reaction can be sufficiently suppressed to increase the amount of alcohol and / or amine introduced into graphite oxide, and a high-quality graphite oxide derivative can be obtained with high efficiency. Further, the graphite oxide derivative obtained by this production method has high crystallinity due to the interaction between the introduced alcohol and / or amine-derived hydrocarbon groups. In addition, in the said manufacturing method, there exists a tendency for the crystallinity of the graphite oxide derivative obtained to become higher, so that there are many carbon numbers of alcohol and / or amine, but even if there are few carbon numbers of alcohol and / or amine. The number of hydrocarbon groups introduced into graphite oxide can be made sufficiently large, and a high-quality graphite oxide derivative can be obtained.
In addition, it is preferable that the said process is what obtains the graphite oxide derivative which has a functional group which has a hydrocarbon group at the terminal, for example by making graphite oxide and alcohol and / or amine react at the reaction temperature of 120 degreeC or more. .
In addition, the above-mentioned patent document and non-patent document describe nothing about obtaining graphite oxide derivatives having a functional group having a hydrocarbon group by reacting graphite oxide with alcohol and / or amine at a reaction temperature of 120 ° C. or higher. Not disclosed.

The present invention is also a graphite oxide derivative having an alkyl group and having a grade of 8 grade as measured by a drop sensitivity test defined in JIS K 4810. For example, in the production method of the present invention, by reacting graphite oxide with alcohol and / or amine at a high reaction temperature as described above, the alkyl group has an alkyl group and the sensitivity of the sensitivity by the sensitivity test is sufficiently reduced. It is possible to obtain (disappeared) high quality graphite oxide derivatives.

The present invention further shows at least one peak at 9-13 ° and 21-24 ° in the X-ray diffraction spectrum, and the crystallite diameter calculated by Scherrer's formula of the peak at 9-13 ° is 100 mm or more. It is also a graphite oxide derivative characterized in that it is 500Å or less. For example, in the production method of the present invention, it is possible to obtain a high quality graphite oxide derivative exhibiting such a peak by reacting graphite oxide with alcohol and / or amine. The above “the crystallite diameter calculated by Scherrer's formula of the peak at 9-13 ° is 100 Å or more and 500 Å or less” means that when there are a plurality of peaks at 9-13 °, any one of the peaks The crystallite diameter calculated by Scherrer's formula may be 100 to 500 mm. Especially, it is preferable that the graphite oxide derivative of the present invention has one peak at 9-13 ° and 21-24 ° in the X-ray diffraction spectrum. The crystallite diameter is more preferably 200 mm or more. Furthermore, it is more preferable that the crystallite diameter is 400 mm or less.
The X-ray diffraction spectrum can be measured by the “XRD measurement method” in the examples.

The reaction time in the step of obtaining the graphite oxide derivative is, for example, preferably 1 hour or more, more preferably 3 hours or more, and further preferably 5 hours or more. The reaction time is preferably 120 hours or less, more preferably 100 hours or less, and more preferably 80 hours or less from the viewpoint of proceeding with the modification reaction while suppressing the reduction reaction sufficiently. Further preferred.

The said reaction process can be performed, stirring using a well-known stirrer etc.
The said reaction process can be performed in air or inert gas atmosphere, such as nitrogen, helium, and argon, for example. In addition, the pressure condition of the reaction step is not particularly limited, and can be performed under a pressurized condition, a normal pressure condition, and a reduced pressure condition. For example, it is preferably performed under a normal pressure condition. Further, particularly when a volatile flocculant is used in the concentration step, it is preferable to perform distillation of impurities such as the flocculant by heating under reduced pressure before the reaction step. Thereby, bumping of a flocculant etc. and side reaction can fully be prevented in a reaction process, and it is possible to advance a reaction process stably.

The graphite oxide derivative obtained by the production method of the present invention has a functional group derived from a compound that reacts with the oxygen-containing functional group of graphite oxide (preferably a functional group having a hydrocarbon group at the terminal) at the terminal. The functional group is not particularly limited, and includes an oxygen-containing group such as an alkoxycarbonyl group (—COOR) or an alkoxyl group (—OR); a sulfur-containing group; an alkylamino group (—NHR, —NRR ′), an alkylamide group ( Nitrogen-containing groups such as —CONHR, —CONRR ′); phosphorus-containing groups, etc., including oxygen-containing groups such as alkoxycarbonyl groups (—COOR) and alkoxyl groups (—OR), alkylamino groups (—NHR, — NRR ′) and a nitrogen-containing group such as an alkylamide group (—CONHR, —CONRR ′) are preferable. R and R 'are the same or different and each represents an organic group, and among them, a hydrocarbon group is preferable.

In the production method of the present invention, the graphite oxide derivative obtained by reacting graphite oxide with alcohol contains carbon atoms, hydrogen atoms, and other atoms other than oxygen atoms in 100% by mass of the graphite oxide derivative. Is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass or less. The graphite oxide derivative is particularly preferably free from other atoms. In other words, it is preferable that the graphite oxide derivative has only carbon atoms, hydrogen atoms, and oxygen atoms as constituent elements. Examples of other atoms include a nitrogen atom, a phosphorus atom, and a halogen atom. In particular, the graphite oxide derivative preferably has a nitrogen atom content of 0.1% by mass or less in 100% by mass of the graphite oxide derivative.
In the production method of the present invention, the graphite oxide derivative obtained by reacting graphite oxide with an amine is a carbon atom, a hydrogen atom, an oxygen atom, and other than nitrogen atoms in 100% by mass of the graphite oxide derivative. The content of atoms is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass or less. The graphite oxide derivative is particularly preferably free from other atoms. In other words, it is preferable that the graphite oxide derivative has only carbon atoms, hydrogen atoms, oxygen atoms, and nitrogen atoms as constituent elements. Examples of other atoms include phosphorus atoms and halogen atoms.

The graphite oxide derivative preferably has an average particle size of 0.01 μm or more and 100 μm or less.
The average particle diameter is more preferably 0.1 μm or more. The average particle diameter is more preferably 60 μm or less.
The average particle diameter can be measured by a particle size distribution measuring device.

Examples of the shape of the graphite oxide derivative include fine powder, powder, granule, granule, scale, polyhedron, rod, and curved surface. The particles having the average particle size in the above range are, for example, pulverized by a ball mill or the like, and the coarse particles obtained by the pulverization are dispersed in a dispersant to obtain a desired particle size, and then dried. In addition to a method, a method of screening the particle size by sieving the particle, a combination of these methods, a method for obtaining (nano) particles having a desired particle size by optimizing the preparation conditions at the stage of particle production, etc. It is possible.

The graphite oxide derivative of the present invention comprises a catalyst, an electrode active material for a battery or a capacitor, a thermoelectric conversion material, a conductive material, a light emitting material, a lubricant additive, a polymer additive, a permeable membrane material, an antibacterial material, a water repellent material It can be suitably used as an adsorbing material. For example, when the graphite oxide derivative of the present invention is introduced with a hydrocarbon group having 5 or more carbon atoms, it is excellent in dispersibility in a nonpolar dispersion medium or an amphiphilic dispersion medium. It can be particularly suitably used as an additive for lubricating oils, additives for resins, and the like.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

In the following Examples and Comparative Examples, analysis and evaluation were performed as follows.
<XRD measurement method>
XRD measurement was performed under the following conditions using a fully automatic horizontal X-ray diffractometer (manufactured by Rigaku Corporation, SMART LAB).
CuKα1 line: 0.15406 nm
Scanning range: 5 ° -45 °
X-ray output setting: 45kV-200mA
Step size: 0.010 °
Scan speed: 0.5 ° min ⁻¹ -4 ° min ⁻¹
The XRD measurement was performed in a state where an inert atmosphere was maintained by loading the sample on an airtight sample stage in a glove box.
<Measurement method of FT-IR>
It measured by mixing a graphite oxide derivative with KBr and pelletizing it using Nicolet NEXTUS670 FTIR by Thermo Fisher Scientific Co., Ltd. Measurement range resolution 900～4000Cm ^-1 was ^{1 cm -1.}
<Analysis of sulfuric acid concentration>
The concentration of sulfuric acid in the graphite oxide-containing composition was confirmed by neutralizing and titrating an aqueous graphite oxide dispersion with an aqueous sodium hydroxide solution.
<Analysis of moisture>
The water concentration in the graphite oxide-containing composition was measured using a trace moisture measuring device AQV-2200A manufactured by Hiranuma Sangyo Co., Ltd.
<Analysis of oxygen content>
The amount of oxygen in graphite oxide or a derivative thereof was analyzed using JPS-9000MX manufactured by JEOL. The result was given as a ratio to carbon (C / O ratio).
In addition, it is thought that the oxygen functional group in graphite oxide is maintained more, so that the oxygen carbon ratio (C / O ratio) of graphite oxide is small. In addition, it is considered that the larger the oxygen-carbon ratio (C / O ratio) of the graphite oxide derivative, the more hydrocarbon groups are introduced into the graphite oxide derivative.
<Sensitivity test>
According to the sensitivity test method defined in JIS K 4810.

(Synthesis of graphite oxide)
Graphite oxide was synthesized by the following steps. Graphite (Z-5F, 5.76 g manufactured by Ito Graphite Co., Ltd.) and sulfuric acid (Wako Pure Chemical Industries, 167 ml) are placed in a reaction vessel in advance, and potassium permanganate (Wako Pure Chemical Industries, Ltd.) is adjusted to 25 ° C. (14.4 g) manufactured by Co., Ltd. was added. After the addition, the temperature was raised to 35 ° C. for 30 minutes and reacted for 2 hours. After the reaction, 890 ml of water and 30% hydrogen peroxide water (88 ml, manufactured by Wako Pure Chemical Industries, Ltd.) were added to stop the reaction while cooling the reactor in an ice bath to obtain a graphite oxide-containing composition (reaction liquid containing graphite oxide). It was.

(Preparation Example 1)
The obtained reaction solution containing graphite oxide was placed in a centrifuge tube for centrifugation and centrifuged at 10,000 G for 10 minutes. After centrifugation, the supernatant was removed to obtain a graphite oxide-containing composition. The sulfuric acid in this composition was 300% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 1.37. The concentration of sulfuric acid can be easily adjusted by adding water appropriately before centrifugation.

(Preparation Example 2)
The graphite oxide-containing composition obtained in Preparation Example 1 was subjected to centrifugation, removal of the supernatant, and redispersion in water a total of 8 times to obtain purified graphite oxide. The sulfuric acid in this composition was 0.01% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 1.59. Compared to Preparation Example 1, it was confirmed that the amount of oxygen decreased by purification. FIG. 1 is an FT-IR chart of graphite oxide produced in Preparation Example 2.

(Preparation Example 3)
The graphite oxide-containing composition obtained in Preparation Example 2 was dried under reduced pressure for 1 hour. The moisture in this composition was 10% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 1.62. Compared with Preparation Example 2, it was found that the oxygen content was not significantly reduced by drying, and the oxygen functional group was stabilized by the presence of moisture.

(Preparation Example 4)
The graphite oxide-containing composition obtained in Preparation Example 2 was dried at 50 ° C. under reduced pressure for 2 days. The water content in this composition was less than 3% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 2.60. Compared to Preparation Example 2, it was confirmed that the amount of oxygen was significantly reduced by heat drying.

(Preparation Example 5)
To the obtained reaction liquid containing graphite oxide, 95% of water and 16% of 1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) as a flocculant were added. The aggregated graphite oxide-containing composition was concentrated by filtration to obtain a paste-like graphite oxide-containing composition. The sulfuric acid in this composition was 3% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 1.42. Concentration by aggregation has also been found to be a suitable technique for maintaining oxygen functional groups. The concentration of sulfuric acid can be easily adjusted by adding water as appropriate before aggregation.

(Preparation Example 6)
The graphite oxide-containing composition obtained in Preparation Example 5 was dried at 50 ° C. under reduced pressure for 2 days. The water content in this composition was less than 3% with respect to graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide was 2.24. Compared to Preparation Example 5, it was confirmed that the amount of oxygen decreased by heat drying.

(Production of graphite oxide derivatives)
A graphite oxide derivative was produced by the following steps.

Example 1
The graphite oxide-containing composition obtained in Preparation Example 5 was transferred to a reactor, and to this was added 500% of 2-decyl-1-tetradecanol (Nippon Rika Co., Ltd., Engecol 240A) with respect to graphite oxide, and 150 The reaction was carried out at 5 ° C. for 5 hours. After the reaction, hexane was poured, filtered, washed with water and acetone, and the obtained solid was vacuum dried at 100 ° C. to obtain graphite oxide derivative A. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative A was 8.5. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8. 2 is an FT-IR chart of graphite oxide derivative A produced in Example 1. FIG. 3 is an XRD chart of the graphite oxide derivative A produced in Example 1. FIG. As shown in FIG. 3, the graphite oxide derivative A has one peak at 9-13 ° and 21-24 ° in the X-ray diffraction spectrum, and is calculated by the Scherrer equation of the peak at 9-13 °. The crystallite diameter was 313 mm.

(Example 2)
The graphite oxide derivative B was obtained by the method described in Example 1, except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 2, and that 10% sulfuric acid was added as a catalyst to the graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative B was 7.5. As compared with Example 1, the modification amount was small and the C / O ratio was low. It was considered that the oxygen functional groups were reduced by the purification, and the amount of modification was small compared to Example 1. FIG. 4 is an FT-IR chart of graphite oxide derivative B produced in Example 2.

(Example 3)
The graphite oxide derivative C was obtained by the method described in Example 1 except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 4 and that 10% sulfuric acid was added to the graphite oxide as a catalyst. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative C was 7.1. As compared with Example 1, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by purification and drying, and the amount of modification was small compared to Example 1. FIG. 5 is an FT-IR chart of the graphite oxide derivative C produced in Example 3.

Example 4
The graphite oxide derivative D was obtained by the method described in Example 1 except that the graphite oxide material used was the graphite oxide obtained in Preparation Example 6 and that 10% sulfuric acid was added as a catalyst to the graphite oxide. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative D was 7.3. As compared with Example 1, the modification amount was small and the C / O ratio was low. It was thought that oxygen functional groups were reduced by drying, and the amount of modification was small compared to Example 1. FIG. 6 is an FT-IR chart of graphite oxide derivative D produced in Example 4.

(Example 5)
A graphite oxide derivative E was obtained by the method described in Example 1, except that 2-ethyl-1-hexanol (Wako Pure Chemical Industries, Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative E was 6.8. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8. FIG. 7 is an FT-IR chart of graphite oxide derivative E produced in Example 5. FIG. 8 is an XRD chart of the graphite oxide derivative E produced in Example 5. As shown in FIG. 8, the graphite oxide E shows one peak at 9-13 ° and 21-24 ° in the X-ray diffraction spectrum, and is calculated by the Scherrer equation of the peak at 9-13 °. The crystallite diameter was 111.6 mm.

(Example 6)
A graphite oxide derivative F was obtained by the method described in Example 2 except that 2-ethyl-1-hexanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative F was 6.2. As compared with Example 5, the modification amount was small and the C / O ratio was low. It was considered that the oxygen functional group was reduced by the purification, and the amount of modification was small as compared with Example 5. FIG. 9 is an FT-IR chart of graphite oxide derivative F produced in Example 6.

(Example 7)
A graphite oxide derivative G was obtained by the method described in Example 3 except that 2-ethyl-1-hexanol (Wako Pure Chemical Industries, Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative G was 6.0. As compared with Example 5, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by purification and drying, and the amount of modification was small compared to Example 5. FIG. 10 is an FT-IR chart of graphite oxide derivative G produced in Example 7.

(Example 8)
A graphite oxide derivative H was obtained by the method described in Example 4 except that 2-ethyl-1-hexanol (Wako Pure Chemical Industries, Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative H was 6.1. As compared with Example 5, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by drying, and the amount of modification was small as compared with Example 5. FIG. 11 is an FT-IR chart of graphite oxide derivative H produced in Example 8.

Example 9
A graphite oxide derivative I was obtained by the method described in Example 1 except that the reaction temperature was 100 ° C. and the reaction time was 24 hours. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative I was 7.1. When the XRD patterns of Example 1 and Example 9 were compared, the graphite oxide derivative A of Example 1 was sharper and higher in crystallinity than the graphite oxide derivative I of Example 9. Moreover, the sensitivity by the calm sensitivity test was 7th grade. FIG. 12 is an FT-IR chart of graphite oxide derivative I produced in Example 9. FIG. 13 is an XRD chart of the graphite oxide derivative I produced in Example 9. As shown in FIG. 13, the graphite oxide derivative I shows one peak at 9-13 ° and 21-24 ° in the X-ray diffraction spectrum, and is calculated by the Scherrer equation of the peak at 9-13 °. The crystallite diameter was 61.8 mm.

(Example 10)
A graphite oxide derivative J was obtained by the method described in Example 5 except that the reaction temperature was 100 ° C. and the reaction was performed for 24 hours. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative J was 6.1. When the XRD patterns of Examples 5 and 10 were compared, the graphite oxide derivative E of Example 5 was sharper and higher in crystallinity than the graphite oxide derivative J of Example 10. Moreover, the sensitivity by the calm sensitivity test was 7th grade. As mentioned above, when Example 1 and Example 9, Example 5 and Example 10 were compared, it turned out that the sensitivity can be lost by setting reaction temperature to 150 degreeC. FIG. 14 is an FT-IR chart of graphite oxide derivative J produced in Example 10. FIG. 15 is an XRD chart of the graphite oxide derivative J produced in Example 10. As shown in FIG. 15, the graphite oxide derivative J showed one peak at 21-24 ° in the X-ray diffraction spectrum, but it did not show a peak at 9-13 °.

(Example 11)
The graphite oxide-containing composition obtained in Preparation Example 5 was transferred to a reactor, and to this was added 500% of 2-decyl-1-tetradecanol (manufactured by Shin Nippon Rika Co., Ltd., Engecol 240A) with respect to graphite oxide, and 100 Water and 1-butanol were distilled off under reduced pressure at ° C. Thereafter, the temperature was raised and the reaction was carried out at 150 ° C. for 5 hours. After the reaction, hexane was poured, filtered, washed with water and acetone, and the obtained solid was vacuum dried at 100 ° C. to obtain graphite oxide derivative X. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative X was 8.7. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8.

Example 12
A graphite oxide derivative Y was obtained by the method described in Example 11 except that 2-ethyl-1-hexanol (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative Y was 6.9. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. From the results of Examples 11 and 12, when a volatile compound such as 1-butanol is used as a flocculant, it is also a preferred form to undergo a vacuum distillation step in advance. Further, the sensitivity according to the sensitivity test was grade 8.

(Example 13)
A graphite oxide derivative AA was obtained by the method described in Example 1 except that stearylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AA was 8.0. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8.

(Example 14)
A graphite oxide derivative AB was obtained by the method described in Example 13, except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 2. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AB was 7.2. As compared with Example 13, the modification amount was small and the C / O ratio was low. It was considered that the oxygen functional groups were reduced by the purification, and the amount of modification was small as compared with Example 13.

(Example 15)
A graphite oxide derivative AC was obtained by the method described in Example 13 except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 4. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AC was 6.6. Compared with Example 13, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by purification and drying, and the amount of modification was small compared to Example 13.

(Example 16)
A graphite oxide derivative AD was obtained by the method described in Example 13 except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 6. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AD was 6.9. As compared with Example 13, the modification amount was small and the C / O ratio was low. It was thought that oxygen functional groups were reduced by drying, and the amount of modification was small compared to Example 13.

(Example 17)
A graphite oxide derivative AE was obtained by the method described in Example 1 except that 2-ethylhexylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 2-decyl-1-tetradecanol. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AE was 6.7. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8.

(Example 18)
A graphite oxide derivative A-F was obtained by the method described in Example 17, except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 2. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative A-F was 6.2. As compared with Example 17, the modification amount was small and the C / O ratio was low. It was considered that the oxygen functional group was reduced by the purification, and the amount of modification was small as compared with Example 17.

(Example 19)
A graphite oxide derivative AG was obtained by the method described in Example 17, except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 4. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AG was 6.0. Compared with Example 17, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by purification and drying, and the amount of modification was small compared to Example 17.

(Example 20)
A graphite oxide derivative A-H was obtained by the method described in Example 17 except that the graphite oxide raw material used was the graphite oxide obtained in Preparation Example 6. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AH was 6.1. As compared with Example 17, the modification amount was small and the C / O ratio was low. It was considered that oxygen functional groups were reduced by drying, and the amount of modification was small compared to Example 17.

(Example 21)
Example: NMP was added as a reaction solvent to 10000% of graphite oxide and dispersed by ultrasonic treatment, and stearylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 2-decyl-1-tetradecanol. The graphite oxide derivative AI was obtained by the method described in 1. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AI was 8.3. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8.

(Example 22)
Except that NMP was added as a reaction solvent to 10000% of graphite oxide and dispersed by ultrasonic treatment, and 2-ethylhexylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 2-decyl-1-tetradecanol. Graphite oxide derivative AJ was obtained by the method described in Example 1. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative AJ was 7.0. Further, in terms of dispersibility, it was also confirmed that the dispersibility was good for chloroform, acetone, DMF, ethanol, and decane. Further, the sensitivity according to the sensitivity test was grade 8.

(Comparative Example 1)
A graphite oxide derivative K was obtained by the method described in Example 3 except that the reaction temperature was 100 ° C. and the reaction time was 24 hours. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative K was 6.0. It was confirmed that the modification amount was small as compared with Examples 1-4. FIG. 16 is an FT-IR chart of graphite oxide derivative K produced in Comparative Example 1.

(Comparative Example 2)
A graphite oxide derivative L was obtained by the method described in Example 7 except that the reaction temperature was 100 ° C. and the reaction time was 24 hours. The oxygen-carbon ratio (C / O ratio) in the obtained graphite oxide derivative L was 5.6. It was confirmed that the modification amount was small as compared with Examples 5-8. FIG. 17 is an FT-IR chart of graphite oxide derivative L produced in Comparative Example 2.

The results of Examples 1 to 22 and Comparative Examples 1 and 2 are shown in Table 1 below.

Claims (11)

A method for producing a graphite oxide derivative comprising:
The production method comprises the steps of oxidizing graphite,
Comprising: reacting a graphite oxide in the graphite oxide-containing composition obtained in the oxidation step with a compound that reacts with an oxygen-containing functional group of the graphite oxide to obtain a graphite oxide derivative;
A method for producing a graphite oxide derivative characterized by not comprising a step of purifying and drying a graphite oxide-containing composition between the oxidation step and the step of obtaining a graphite oxide derivative. The method for producing a graphite oxide derivative according to claim 1, wherein a step of purifying the graphite oxide-containing composition is not included between the oxidation step and the step of obtaining the graphite oxide derivative. The method for producing a graphite oxide derivative according to claim 1 or 2, wherein the oxidizing step oxidizes graphite using an acid. The method for producing a graphite oxide derivative according to any one of claims 1 to 3, wherein the compound that reacts with the oxygen-containing functional group of graphite oxide is an alcohol and / or an amine. The step of obtaining the graphite oxide derivative includes a step of reacting graphite oxide and a compound that reacts with an oxygen-containing functional group of graphite oxide at a reaction temperature of 120 ° C. or more. A method for producing the graphite oxide derivative according to claim 1. The graphite oxide-containing composition subjected to the reaction in the step of obtaining the graphite oxide derivative contains 1% by mass or more and 1000% by mass or less of sulfuric acid with respect to 100% by mass of the graphite oxide in the composition. The manufacturing method of the graphite oxide derivative in any one of Claims 1-5. The graphite oxide-containing composition subjected to the reaction in the step of obtaining the graphite oxide derivative contains 3% by mass or more and 10,000% by mass or less of water with respect to 100% by mass of the graphite oxide in the composition. A method for producing a graphite oxide derivative according to any one of claims 1 to 6. A method for producing a graphite oxide derivative comprising:
The production method comprises a step of obtaining a graphite oxide derivative having a functional group having a hydrocarbon group by reacting graphite oxide with alcohol and / or an amine at a reaction temperature of 120 ° C. or more. Manufacturing method. The alcohol is an aliphatic alcohol;
The method for producing a graphite oxide derivative according to claim 4 or 8, wherein the amine is an aliphatic amine. Having an alkyl group,
A graphite oxide derivative characterized in that the grade measured by a sag sensitivity test specified in JIS K 4810 is grade 8. In the X-ray diffraction spectrum, at least one peak is shown at 9-13 ° and 21-24 °, and the crystallite diameter calculated by Scherrer's formula of the peak at 9-13 ° is 100 mm or more and 500 mm or less. A graphite oxide derivative characterized by that.

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