JP2021006497A - Method for producing low-defect carbon material - Google Patents
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- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
Description
本発明は、低欠陥化炭素材料の製造方法に関する。より詳しくは、放熱材料、触媒、電極材料等として好適に用いることができる可能性がある低欠陥化炭素材料の製造方法、及び、炭素材料の改質方法に関する。 The present invention relates to a method for producing a low-defect carbon material. More specifically, the present invention relates to a method for producing a low-defect carbon material which may be suitably used as a heat radiating material, a catalyst, an electrode material, and the like, and a method for modifying a carbon material.
グラフェン系炭素材料は、安価で豊富であるとともに、触媒性能や、機械的強度、電気伝導性、熱伝導性等の点で放熱材料、触媒、電極材料等の種々の用途への利用が期待され、数多くの研究開発が行われている。 Graphene-based carbon materials are inexpensive and abundant, and are expected to be used in various applications such as heat-dissipating materials, catalysts, and electrode materials in terms of catalytic performance, mechanical strength, electrical conductivity, thermal conductivity, and the like. , A lot of research and development is being done.
例えば、液パルスインジェクション（ＬＰＩ）法で得られるカーボンナノファイバーや、かさ高い還元型酸化グラフェン（ｒＧＯ）にマイクロ波を照射すると効率的に放電が起き、これによって高結晶化や欠陥密度の低下が進行することが報告されている（例えば、特許文献１、非特許文献１）。この他にも、還元型酸化グラフェンにマイクロ波を照射する方法が報告されている（例えば、非特許文献２）。 For example, when carbon nanofibers obtained by the liquid pulse injection (LPI) method or bulky reduced graphene oxide (rGO) is irradiated with microwaves, electric discharge occurs efficiently, which leads to high crystallization and reduction of defect density. It has been reported to progress (for example, Patent Document 1, Non-Patent Document 1). In addition to this, a method of irradiating reduced graphene oxide with microwaves has been reported (for example, Non-Patent Document 2).
しかしながら、グラフェン系炭素材料の欠陥をより少ないものとし、電気伝導性、熱伝導性、潤滑性、強度、触媒性能等をより優れたものとすることが望まれるところであった。 However, it has been desired to reduce the defects of the graphene-based carbon material and to improve the electrical conductivity, thermal conductivity, lubricity, strength, catalytic performance and the like.
本発明は、上記現状に鑑みてなされたものであり、欠陥が非常に少ないグラフェン系炭素材料を得る方法を提供することを目的とする。 The present invention has been made in view of the above situation, and an object of the present invention is to provide a method for obtaining a graphene-based carbon material having very few defects.
本発明者らは、欠陥が非常に少ないグラフェン系炭素材料を得る方法について種々検討し、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射すると、当該炭素材料の低欠陥化が顕著なものとなり、上記課題をみごとに解決することができることに想到し、本発明に到達したものである。また、本発明者らは、このようにして得られた低欠陥化炭素材料が耐酸化性にも優れることを見出した。 The present inventors have studied various methods for obtaining a graphene-based carbon material having very few defects, and when the carbon material having a G-band peak in the Raman spectrum is fluidized and the carbon material is irradiated with microwaves, the invention is described. The present invention has been reached with the idea that the reduction of defects in the carbon material has become remarkable and the above problems can be solved brilliantly. Further, the present inventors have found that the defect-reduced carbon material thus obtained is also excellent in oxidation resistance.
すなわち本発明は、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射する工程を含むことを特徴とする低欠陥化炭素材料の製造方法である。
本発明はまた、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射する工程を含むことを特徴とする炭素材料の改質方法である。
以下に本発明を詳述する。
That is, the present invention is a method for producing a low-defect carbon material, which comprises a step of irradiating the carbon material with microwaves while fluidizing the carbon material having a G band peak in the Raman spectrum.
The present invention is also a method for modifying a carbon material, which comprises a step of irradiating the carbon material with microwaves while fluidizing the carbon material having a G-band peak in the Raman spectrum.
The present invention will be described in detail below.
本発明の低欠陥化炭素材料の製造方法により、欠陥が非常に少ない低欠陥化炭素材料を得ることができる。 According to the method for producing a low-defect carbon material of the present invention, a low-defect carbon material having very few defects can be obtained.
以下に本発明を詳述する。
なお、以下において記載する本発明の個々の好ましい形態を２つ以上組み合わせたものもまた、本発明の好ましい形態である。
The present invention will be described in detail below.
It should be noted that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.
＜低欠陥化炭素材料の製造方法＞
本発明の低欠陥化炭素材料の製造方法は、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料（以下、単に炭素材料とも言う。）を流動化しながら、該炭素材料にマイクロ波を照射する工程を含む。
なお、本明細書中、低欠陥化とは、ラマンスペクトルにおけるＧバンドのピーク強度に対するＤバンドのピーク強度の比（ＩＤ／ＩＧ）が減少することを言う。欠陥が少ない方が、電子がよく流れるようになり、電気伝導性がより優れるものとなるとともに、熱伝導性、潤滑性、強度、触媒性能等もより優れるものとなる。本発明の製造方法により炭素材料の低欠陥化が進む原理は不明であるが、炭素材料を流動化することで、炭素材料間の距離が適度なものとなって放電が発生しやすくなり、この放電により炭素材料が高エネルギー化し、黒鉛化が進んでいる可能性がある。好ましい流動化状態としては、照射工程においてマイクロ波を照射される炭素材料が、後述する好ましい最大流動かさ密度の範囲や好ましい粒径範囲を満たすものが挙げられる。このような好ましい流動化状態では、炭素材料間の距離がより適度なものになる結果、低欠陥化が顕著なものになると考えられる。また、Ｇバンドのピーク、Ｄバンドのピークについては、後述する。
<Manufacturing method of low-defect carbon material>
In the method for producing a low-defect carbon material of the present invention, a step of irradiating the carbon material with microwaves while fluidizing the carbon material having a G band peak in the Raman spectrum (hereinafter, also simply referred to as carbon material) is performed. Including.
In the present specification, "reducing defects" means that the ratio of the peak intensity of the D band to the peak intensity of the G band ( ID / IG ) in the Raman spectrum is reduced. The smaller the number of defects, the better the flow of electrons, the better the electrical conductivity, and the better the thermal conductivity, lubricity, strength, catalytic performance, and the like. The principle of reducing defects in the carbon material by the production method of the present invention is unknown, but by fluidizing the carbon material, the distance between the carbon materials becomes appropriate and an electric discharge is likely to occur. There is a possibility that the carbon material has increased energy due to the electric discharge and graphitization is progressing. Preferred fluidization states include those in which the carbon material irradiated with microwaves in the irradiation step satisfies the range of the preferred maximum flow bulk density and the preferred particle size range described later. In such a preferable fluidized state, the distance between the carbon materials becomes more appropriate, and as a result, the defect reduction is considered to be remarkable. The G band peak and the D band peak will be described later.
本発明の低欠陥化炭素材料の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、上向きのガス流れにより流動化されていることが好ましい。上向きのガス流れにより、炭素材料が適度に流動化し、炭素材料の低欠陥化がより進むことになる。
上向きのガス流れとは、上向きの成分を含むガス流れであればよいが、上向きの成分が主体であるガス流れ（ガス流量〔線速度〕を上向き成分と水平成分に分解した場合に、上向き成分が水平成分よりも大きいガス流れ）であることが好ましい。
In the method for producing a low-defect carbon material of the present invention, it is preferable that the carbon material irradiated with microwaves in the irradiation step is fluidized by an upward gas flow. Due to the upward gas flow, the carbon material is moderately fluidized, and the defects of the carbon material are further reduced.
The upward gas flow may be a gas flow containing an upward component, but a gas flow mainly composed of an upward component (when the gas flow rate [linear velocity] is decomposed into an upward component and a horizontal component, the upward component is used. Is a gas flow larger than the horizontal component).
本発明の低欠陥化炭素材料の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、最大流動かさ密度（最大動かさ密度）が０．２８ｇ／ｃｍ３未満となるように流動化されていることが好ましい。
上記最大流動かさ密度は、０．２４ｇ／ｃｍ３以下であることが好ましく、０．２０ｇ／ｃｍ３以下であることがより好ましく、０．１０ｇ／ｃｍ３以下であることが更に好ましく、０．０４ｇ／ｃｍ３以下であることが特に好ましい。
上記最大流動かさ密度は、０．００１ｇ／ｃｍ３以上であることが好ましく、０．００５ｇ／ｃｍ３以上であることがより好ましく、０．０１ｇ／ｃｍ３以上であることが更に好ましく、０．０２ｇ／ｃｍ３以上であることが特に好ましい。
上記最大流動かさ密度が上記範囲内であることで、流動化が適度なものとなり、低欠陥化がより顕著なものとなる。
上記最大流動かさ密度は、マイクロ波照射開始後の試料体積（試料が流動している空間の体積）の最大値に対する試料の質量から算出され、マイクロ波照射開始後の試料体積は、マイクロ波照射開始後の、各時点での、試料が流動している空間の高さ、幅（縦幅・横幅等）、及び、形状にもとづいて算出される。試料が流動している空間の高さ、幅、及び、形状は、試料を流動化させながらのマイクロ波照射開始から照射終了までの、映像（必要に応じて、複数の視点からの映像）から読み取る。映像の解像度、背景等は、使用する試料の粒径、色合い等に応じて、流動している試料を視認できるように適宜設定すればよい。なお、例えば細長い管型反応器中の試料に対してマイクロ波照射を行い、試料が流動している空間の幅を管型反応器内径と同一視でき、試料が流動している空間の形状を管型反応器の内部空間の形状と同一視できる場合は、上記試料体積は、管型反応器内径と試料が流動している高さから算出して求めることができる。
In the method for producing a low-defect carbon material of the present invention, the carbon material irradiated with microwaves in the above irradiation step is fluidized so that the maximum flow bulk density (maximum moving density) is less than 0.28 g / cm 3 . It is preferable that it is.
The maximum flow bulk density is preferably at 0.24 g / cm 3 or less, more preferably more preferably 0.20 g / cm 3 or less, 0.10 g / cm 3 or less, 0. It is particularly preferably 04 g / cm 3 or less.
The maximum flow bulk density is preferably at 0.001 g / cm 3 or more, more preferably 0.005 g / cm 3 or more, further preferably 0.01 g / cm 3 or more, 0. It is particularly preferable that it is 02 g / cm 3 or more.
When the maximum flow bulk density is within the above range, the fluidization becomes appropriate and the defect reduction becomes more remarkable.
The maximum flow bulk density is calculated from the mass of the sample with respect to the maximum value of the sample volume (volume of the space in which the sample is flowing) after the start of microwave irradiation, and the sample volume after the start of microwave irradiation is the microwave irradiation. It is calculated based on the height, width (length, width, etc.) and shape of the space in which the sample is flowing at each time point after the start. The height, width, and shape of the space in which the sample is flowing can be determined from the images (images from multiple viewpoints, if necessary) from the start of microwave irradiation to the end of irradiation while fluidizing the sample. read. The resolution, background, etc. of the image may be appropriately set so that the flowing sample can be visually recognized according to the particle size, color, etc. of the sample to be used. For example, by irradiating a sample in an elongated tubular reactor with microwaves, the width of the space in which the sample is flowing can be equated with the inner diameter of the tubular reactor, and the shape of the space in which the sample is flowing can be determined. When the shape of the internal space of the tubular reactor can be equated, the sample volume can be calculated from the inner diameter of the tubular reactor and the height at which the sample is flowing.
上述した上向きのガス流れの線速度は、最大流動かさ密度が好適な範囲内となるように適宜調整すればよいが、例えば毎分３ｃｍ以上であることが好ましい。また、該ガス流れの線速度は、毎分１５０ｃｍ以下であることが好ましい。 The linear velocity of the upward gas flow described above may be appropriately adjusted so that the maximum flow bulk density is within a suitable range, but is preferably 3 cm or more per minute, for example. Further, the linear velocity of the gas flow is preferably 150 cm or less per minute.
炭素材料を流動化させるためのガスは、特に限定されず、例えば酸素等の活性ガス、窒素、ヘリウム、アルゴン等の不活性ガスとすることができる。中でも、不活性ガスが好ましい。
なお、上記照射工程は、例えば、マイクロ波照射装置内に石英管等の試験管（管型反応器）を配置し、試験管に原料である炭素材料を入れ、試験管の下側から上側に向けてガスを流し、炭素材料を流動化することで行うことができる（例えば、図１参照。）。
The gas for fluidizing the carbon material is not particularly limited, and may be, for example, an active gas such as oxygen or an inert gas such as nitrogen, helium, or argon. Of these, an inert gas is preferable.
In the above irradiation step, for example, a test tube (tube type reactor) such as a quartz tube is placed in a microwave irradiation device, a carbon material as a raw material is put in the test tube, and the test tube is placed from the lower side to the upper side. This can be done by flowing gas towards and fluidizing the carbon material (see, for example, FIG. 1).
本発明の製造方法において、上記照射工程で照射されるマイクロ波は、波長が１００μｍ〜１ｍの範囲内の電磁波である。
上記マイクロ波の周波数は、例えば３００ＭＨｚ〜３００ＧＨｚの範囲内であることが好ましく、５００ＭＨｚ〜５０ＧＨｚの範囲内であることがより好ましく、９００ＭＨｚ〜２５ＧＨｚの範囲内であることが更に好ましい。
In the production method of the present invention, the microwave irradiated in the irradiation step is an electromagnetic wave having a wavelength in the range of 100 μm to 1 m.
The frequency of the microwave is, for example, preferably in the range of 300 MHz to 300 GHz, more preferably in the range of 500 MHz to 50 GHz, and even more preferably in the range of 900 MHz to 25 GHz.
上記マイクロ波の照射温度は、例えば−５０℃以上であることが好ましく、０℃以上であることがより好ましい。また、該照射温度は、１０００℃以下であることが好ましく、５００℃以下であることがより好ましい。
なお、該照射温度は、マイクロ波の照射を行う際の雰囲気の温度であり、マイクロ波の照射開始時の温度が上記温度であることが好ましい。
The irradiation temperature of the microwave is preferably, for example, −50 ° C. or higher, and more preferably 0 ° C. or higher. The irradiation temperature is preferably 1000 ° C. or lower, more preferably 500 ° C. or lower.
The irradiation temperature is the temperature of the atmosphere when the microwave is irradiated, and the temperature at the start of the microwave irradiation is preferably the above temperature.
上記マイクロ波の照射時間（炭素材料を流動化しながらマイクロ波を照射する時間）は、例えば１０秒以上であることが好ましく、３０秒以上であることがより好ましく、１分以上であることが更に好ましく、２分以上であることが特に好ましい。また、該マイクロ波の照射時間は、１２０分以下であることが好ましく、６０分以下であることがより好ましく、４０分以下であることが更に好ましく、２０分以下であることが特に好ましい。 The microwave irradiation time (time for irradiating the microwave while fluidizing the carbon material) is preferably, for example, 10 seconds or more, more preferably 30 seconds or more, and further preferably 1 minute or more. It is preferably 2 minutes or more, and particularly preferably 2 minutes or more. Further, the irradiation time of the microwave is preferably 120 minutes or less, more preferably 60 minutes or less, further preferably 40 minutes or less, and particularly preferably 20 minutes or less.
本発明に係る炭素材料がラマンスペクトルにおいて有するＧバンドのピークは、炭素原子で構成される連続した６員環構造に由来する、ラマンシフト１５５０〜１６２０ｃｍ−１のピークである。
なお、Ｄバンドのピークは、構造の乱れと欠陥に由来する、ラマンシフト１２７０〜１４５０ｃｍ−１のピークである。
The G-band peak of the carbon material according to the present invention in the Raman spectrum is a peak of Raman shift 1550 to 1620 cm -1 derived from a continuous 6-membered ring structure composed of carbon atoms.
The peak of the D band is a peak of Raman shift 1270 to 1450 cm -1 due to structural disorder and defects.
本明細書中、所定のラマンシフトの範囲のピークとは、ベースラインに対して当該ラマンシフトの範囲内にピークトップが明確に観測されるものであればよい。例えば、Ｇバンドであれば１５５０〜１６２０ｃｍ−１の範囲内に明確なピークトップが存在するということである。なお、ピークトップは１５５０〜１６２０ｃｍ−１の範囲内に無いがピークのショルダーがその範囲内にかかっているというだけでは、ラマンシフト１５５０〜１６２０ｃｍ−１のピークとは言わない。
なお、本明細書中、ラマンスペクトルは、実施例に記載の方法で測定されるものである。
In the present specification, the peak in the predetermined Raman shift range may be one in which the peak top is clearly observed within the range of the Raman shift with respect to the baseline. For example, in the case of the G band, there is a clear peak top in the range of 1550 to 1620 cm -1 . The peak top is not within the range of 1550 to 1620 cm -1 , but the fact that the shoulder of the peak is within that range does not mean that it is the peak of Raman shift 1550 to 1620 cm -1 .
In this specification, the Raman spectrum is measured by the method described in Examples.
本発明の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、ラマンスペクトルにおいてＧバンドのピークを有するものであればよく、例えば酸化黒鉛、還元型酸化黒鉛、カーボンナノファイバー、カーボンナノチューブ等が挙げられ、これらの１種又は２種以上を使用できるが、中でも還元型酸化黒鉛が好ましい。還元型酸化黒鉛は比重が重く低欠陥化が進みにくいところ、本発明の製造方法を適用することで、充分に低欠陥化することができる。 In the production method of the present invention, the carbon material to be irradiated with microwaves in the irradiation step may be any material having a G band peak in the Raman spectrum, for example, graphite oxide, reduced graphite oxide, carbon nanofibers, carbon. Examples thereof include nanotubes, and one or more of these can be used, but reduced graphite oxide is preferable. Since reduced graphite has a heavy specific gravity and it is difficult to reduce defects, the defects can be sufficiently reduced by applying the production method of the present invention.
上記還元型酸化黒鉛は、酸化黒鉛が還元剤等により還元されて得られるものである。
また上記還元型酸化黒鉛は、ＸＰＳ分析で検出される全元素の総和１００原子％中、酸素量が２０原子％以下であることが好ましく、１９原子％以下であることがより好ましく、１８原子％以下であることが更に好ましく、１７原子％以下であることが特に好ましい。
The reduced graphite oxide is obtained by reducing graphite oxide with a reducing agent or the like.
Further, the reduced graphite oxide preferably has an oxygen content of 20 atomic% or less, more preferably 19 atomic% or less, and 18 atomic% or less, based on 100 atomic% of the total elements detected by XPS analysis. It is more preferably 17 atomic% or less, and particularly preferably 17 atomic% or less.
上記還元型酸化黒鉛は、更に、窒素含有基、硫黄含有基等の官能基を有していてもよいが、ＸＰＳ分析で検出される全元素の総和１００原子％中、炭素、水素、及び、酸素以外の元素量が３原子％以下であることが好ましく、１原子％以下であることがより好ましく、還元型酸化黒鉛が炭素、水素、及び、酸素のみを構成元素とするものであることが更に好ましい。
上記酸素量、炭素、水素、及び、酸素以外の元素量、全元素の総和は、実施例に記載のＸＰＳ測定により測定することができる。
The reduced graphite oxide may further have functional groups such as a nitrogen-containing group and a sulfur-containing group, but carbon, hydrogen, and carbon, hydrogen, and carbon, hydrogen, and so on in 100 atomic% of the total of all the elements detected by XPS analysis. The amount of elements other than oxygen is preferably 3 atomic% or less, more preferably 1 atomic% or less, and the reduced graphite oxide contains only carbon, hydrogen, and oxygen as constituent elements. More preferred.
The amount of oxygen, the amount of carbon, hydrogen, the amount of elements other than oxygen, and the total of all elements can be measured by the XPS measurement described in the examples.
上記還元型酸化黒鉛は、その積層数は特に限定されないが、例えば炭素原子１層のみからなるシートであるか、又は、２層〜１００層積層した構造を有するものが好ましい。このような積層数のものを還元型酸化グラフェンとも言う。中でも、積層数が２０層以下であることがより好ましい。 The number of layers of the reduced graphite oxide is not particularly limited, but for example, a sheet composed of only one carbon atom layer or a structure in which two to 100 layers are laminated is preferable. Those having such a number of layers are also called reduced graphene oxide. Above all, it is more preferable that the number of layers is 20 or less.
なお、酸化黒鉛は、Ｈｕｍｍｅｒｓ法における酸化方法を採用した、黒鉛と硫酸とを含む混合液に過マンガン酸塩を添加する工程を含む方法等により適宜得ることができる。 Graphite oxide can be appropriately obtained by a method including a step of adding permanganate to a mixed solution containing graphite and sulfuric acid, which employs the oxidation method in the Hummers method.
本発明の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、粒径範囲が０．０１ｍｍ以上、２．４ｍｍ以下であることが好ましい。
上記粒径範囲は、０．０２ｍｍ以上、２．０ｍｍ以下であることがより好ましく、０．０５ｍｍ以上、１．５ｍｍ以下であることが更に好ましく、０．１ｍｍ以上、１．０ｍｍ以下であることが特に好ましい。
粒径を上記範囲内とすること、特に、上記粒径範囲内である程度小さいものとすることで、低欠陥化がより顕著なものとなる。炭素材料の粒径が小さく、その数が多いと、炭素材料間の距離が適度で放電を起こすものの数も増えるためであると考えられる。
本実施例では、上記粒径範囲は、目開きが上記粒径範囲内にあるふるいを用いた分級操作によって規定している。
また上記炭素材料の平均粒径が上記好ましい粒径範囲内であることもまた好ましい。例えば、本発明の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、平均粒径が０．０１ｍｍ以上、２．４ｍｍ以下であることが好ましい。平均粒径は、レーザー回折・散乱式粒度分布測定装置により測定した体積基準の平均粒径である。
In the production method of the present invention, the carbon material to be irradiated with microwaves in the irradiation step preferably has a particle size range of 0.01 mm or more and 2.4 mm or less.
The particle size range is more preferably 0.02 mm or more and 2.0 mm or less, further preferably 0.05 mm or more and 1.5 mm or less, and 0.1 mm or more and 1.0 mm or less. Is particularly preferable.
Defect reduction becomes more remarkable by setting the particle size within the above range, particularly by setting the particle size within the above range to some extent. This is thought to be because if the particle size of the carbon material is small and the number is large, the distance between the carbon materials is appropriate and the number of substances that cause an electric discharge also increases.
In this embodiment, the particle size range is defined by a classification operation using a sieve whose mesh size is within the particle size range.
It is also preferable that the average particle size of the carbon material is within the preferable particle size range. For example, in the production method of the present invention, the carbon material irradiated with microwaves in the irradiation step preferably has an average particle size of 0.01 mm or more and 2.4 mm or less. The average particle size is a volume-based average particle size measured by a laser diffraction / scattering type particle size distribution measuring device.
本発明の製造方法において、上記照射工程においてマイクロ波を照射される炭素材料は、静かさ密度（静置状態のかさ密度）が０．０５ｇ／ｃｍ３以上、１．０ｇ／ｃｍ３以下であることが好ましい。
上記静かさ密度は、０．１０ｇ／ｃｍ３以上、０．５ｇ／ｃｍ３以下であることがより好ましく、０．１５ｇ／ｃｍ３以上、０．３５ｇ／ｃｍ３以下であることが更に好ましい。
例えば還元型酸化黒鉛のように静かさ密度が上記範囲内で高く、低欠陥化が進みにくいものであっても、本発明の製造方法を適用することで、充分に低欠陥化することができる。したがって、静かさ密度が上記範囲内であることで、発明の効果（本発明に係る照射工程の技術的意義）がより顕著なものとなると言える。
上記静かさ密度は、炭素材料を、２０ｍＬメスシリンダーに静かに入れ質量を測定し、続いてこれを体積変化が殆ど認められなくなるまで（７００回）タップした際の体積を読み取ることにより求めることができる。
In the production method of the present invention, carbon material is irradiated with microwaves in the irradiation process, quiet density (bulk density of a stationary state) is 0.05 g / cm 3 or more, is 1.0 g / cm 3 or less Is preferable.
The quietness density is more preferably 0.10 g / cm 3 or more and 0.5 g / cm 3 or less, and further preferably 0.15 g / cm 3 or more and 0.35 g / cm 3 or less.
For example, even if the quietness density is high within the above range and it is difficult to reduce defects such as reduced graphite oxide, the defects can be sufficiently reduced by applying the production method of the present invention. .. Therefore, it can be said that the effect of the present invention (technical significance of the irradiation step according to the present invention) becomes more remarkable when the quietness density is within the above range.
The quietness density can be determined by gently placing the carbon material in a 20 mL graduated cylinder, measuring the mass, and then reading the volume when the carbon material is tapped until almost no volume change is observed (700 times). it can.
上記炭素材料は、マイクロ波を照射される際に、その他の成分との混合物であってもよいが、混合物中、炭素材料の含有割合が９０質量％以上であることが好ましく、９５質量％以上であることがより好ましく、９９質量％以上であることが更に好ましく、実質的に炭素材料からなるものであることが特に好ましい。 The carbon material may be a mixture with other components when irradiated with microwaves, but the content ratio of the carbon material in the mixture is preferably 90% by mass or more, and 95% by mass or more. It is more preferable that the content is 99% by mass or more, and it is particularly preferable that the material is substantially made of a carbon material.
なお、照射工程後は、得られた低欠陥化炭素材料の酸洗や水洗、乾燥等を適宜行うことができる。 After the irradiation step, the obtained low-defect carbon material can be pickled, washed with water, dried, or the like as appropriate.
本発明の製造方法により得られた低欠陥化炭素材料は、ラマンスペクトルにおけるＧバンドのピーク強度に対するＤバンドのピーク強度の比（ＩＤ／ＩＧ）が１．３以下であることが好ましく、１．０以下であることがより好ましく、０．８以下であることが更に好ましく、０．６５以下であることが一層好ましく、０．５以下であることが特に好ましい。該ピーク強度の比（ＩＤ／ＩＧ）の絶対値は、その下限値は特に限定されず、０であってもよい。
また本発明の製造方法により、低欠陥化炭素材料の上記ピーク強度の比（ＩＤ／ＩＧ）が原料の炭素材料のＩＤ／ＩＧと比べて０．２以上減少することが好ましく、０．３以上減少することがより好ましく、０．４以上減少することが更に好ましい。ＩＤ／ＩＧの減少量は、その上限値は特に限定されないが、通常２以下である。
上記ピーク強度の比（ＩＤ／ＩＧ）は、実施例に記載の方法で測定することができる。
The defect-reduced carbon material obtained by the production method of the present invention preferably has a ratio of the peak intensity of the D band to the peak intensity of the G band ( ID / IG ) in the Raman spectrum of 1.3 or less. It is more preferably 1.0 or less, further preferably 0.8 or less, further preferably 0.65 or less, and particularly preferably 0.5 or less. The lower limit of the absolute value of the peak intensity ratio ( ID / IG ) is not particularly limited and may be 0.
Also by the production method of the present invention, it is preferable to reduce 0.2 or higher than the ratio of the peak intensity of the low defect carbon material (I D / I G) is the I D / I G of the carbon material of the raw material, A decrease of 0.3 or more is more preferable, and a decrease of 0.4 or more is further preferable. Reduction of I D / I G, the upper limit is not particularly limited, it is usually 2 or less.
The peak intensity ratio ( ID / IG ) can be measured by the method described in Examples.
本発明の製造方法により得られた低欠陥化炭素材料は、非常に欠陥が少ないため、放熱材料、触媒、電極材料等として有用である。 The low-defect carbon material obtained by the production method of the present invention has very few defects, and is therefore useful as a heat-dissipating material, a catalyst, an electrode material, and the like.
＜炭素材料の改質方法＞
本発明はまた、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射する工程を含むことを特徴とする炭素材料の改質方法である。
本発明の改質方法により、炭素材料を充分に低欠陥化することができ、放熱材料、触媒、電極材料等として好適なものとなる。
なお、本発明の改質方法における照射工程の好ましい形態は、上述した本発明の製造方法における照射工程の好ましい形態と同様である。
<Method of modifying carbon material>
The present invention is also a method for modifying a carbon material, which comprises a step of irradiating the carbon material with microwaves while fluidizing the carbon material having a G-band peak in the Raman spectrum.
According to the modification method of the present invention, the carbon material can be sufficiently reduced in defects, and is suitable as a heat radiating material, a catalyst, an electrode material and the like.
The preferred form of the irradiation step in the modification method of the present invention is the same as the preferred form of the irradiation step in the manufacturing method of the present invention described above.
以下に実施例を掲げて本発明を更に詳細に説明するが、本発明はこれらの実施例のみに限定されるものではない。なお、特に断りのない限り、「部」は「質量部」を、「％」は「質量％」を意味するものとする。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, "part" means "part by mass" and "%" means "% by mass".
下記実施例及び比較例においては、次のようにして分析し、評価を行った。
＜低欠陥化の進行度合いの評価＞
Cancado, L. G. et al., App. Phys. Lett. 88.16 (2006) 163106-163106に記載の方法に沿って、試料の低欠陥化の進行度合いをラマン分光測定により評価した。
In the following examples and comparative examples, the analysis and evaluation were carried out as follows.
<Evaluation of the degree of progress in reducing defects>
The degree of progress of sample defect reduction was evaluated by Raman spectroscopy according to the method described in Cancado, LG et al., App. Phys. Lett. 88.16 (2006) 163106-163106.
（調製例１〔酸化グラフェン水分散体の調製〕）
酸化グラフェン水分散体を以下の工程で合成した。反応容器にあらかじめ黒鉛（伊藤黒鉛株式会社製Ｚ−２５）１．００質量部、硫酸（和光純薬工業株式会社製）４２．６７質量部を入れ、３０℃に調整しながら過マンガン酸カリウム（和光純薬工業株式会社製）３．５０質量部を入れた。投入後、３５℃に昇温し２時間反応（熟成）させて生成物のスラリー（酸化黒鉛含有スラリー）を得た。次に、８０．００質量部のイオン交換水が入った別の容器にイオン交換水を撹拌しながらスラリー２０．００質量部を加え、３０％過酸化水素水（和光純薬工業株式会社製）１．０８質量部を更に加えて反応停止させた。得られた反応液（スラリー）は静置沈降により、上澄みの除去とイオン交換水による再分散を繰り返し精製した。精製後、流通型分散装置により剥離操作を行い、遠心分離処理した後に上澄みを除去することにより酸化グラフェン水分散体を調製した。得られた酸化グラフェン水分散体における酸化グラフェンの濃度は１．２質量％であった。
(Preparation Example 1 [Preparation of aqueous graphene oxide dispersion])
An aqueous dispersion of graphene oxide was synthesized by the following steps. Put 1.00 parts by mass of graphite (Z-25 manufactured by Ito Graphite Co., Ltd.) and 42.67 parts by mass of sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) in the reaction vessel in advance, and adjust the temperature to 30 ° C. Wako Pure Chemical Industries, Ltd.) 3.50 parts by mass was added. After charging, the temperature was raised to 35 ° C. and the mixture was reacted (aged) for 2 hours to obtain a product slurry (graphite oxide-containing slurry). Next, add 20.00 parts by mass of the slurry to another container containing 80.00 parts by mass of ion-exchanged water while stirring the ion-exchanged water, and add 30% hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.). The reaction was stopped by further adding 1.08 parts by mass. The obtained reaction solution (slurry) was repeatedly purified by removing the supernatant and redispersing with ion-exchanged water by static sedimentation. After purification, a peeling operation was performed with a distribution type disperser, and after centrifugation, the supernatant was removed to prepare an aqueous dispersion of graphene oxide. The concentration of graphene oxide in the obtained aqueous graphene oxide dispersion was 1.2% by mass.
（調製例２〔酸化グラフェン還元物の粉末およびペレットの調製〕）
反応容器に調製例１で得た酸化グラフェン水分散体１００．００質量部を入れ、内温を７５℃に調整し、よく撹拌しながらＬ−アスコルビン酸（和光純薬工業株式会社製）６．００質量部を投入し、酸化グラフェンの還元反応を実施した。反応時間は１時間とした。得られた酸化グラフェン還元物含有スラリーを濾過水洗し、得られたウェットケーキを１００℃で乾燥することにより酸化グラフェン還元物の粉末を得た。ＸＰＳ測定の結果、得られた酸化グラフェン還元物の粉末の元素％は、炭素／酸素＝８５／１５であった。得られた酸化グラフェン還元物の粉末の一部を粉末プレス機で圧縮成型して、酸化グラフェン還元物のペレットを得た。
(Preparation Example 2 [Preparation of graphene oxide reduced powder and pellets])
6. Put 100.00 parts by mass of the graphene oxide aqueous dispersion obtained in Preparation Example 1 in a reaction vessel, adjust the internal temperature to 75 ° C., and stir well with L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd.). 00 parts by mass was charged and a reduction reaction of graphene oxide was carried out. The reaction time was 1 hour. The obtained graphene oxide-containing slurry was washed with filtered water, and the obtained wet cake was dried at 100 ° C. to obtain a graphene oxide-reduced product powder. As a result of XPS measurement, the element% of the obtained graphene oxide reduced powder was carbon / oxygen = 85/15. A part of the obtained graphene oxide reduced powder was compression-molded with a powder press to obtain pellets of the graphene reduced product.
（実施例１〜６、比較例１〜３）
１．試料のふるい分け
調製例２で得た酸化グラフェン還元物のペレット約５ｇを粉砕し、ステンレス製ふるいを用いて、（ｉ）０．６ｍｍ以下、（ｉｉ）０．６〜１．０ｍｍ、（ｉｉｉ）１．０〜２．３６ｍｍ、（ｉｖ）２．３６ｍｍ以上の４領域の粒径範囲に分級した。なお、前記粉砕後の試料の一部については、分級せずに粉砕未分級品とした。粉砕未分級品の静かさ密度は、０．２８３ｇ／ｃｍ３であった。
(Examples 1 to 6, Comparative Examples 1 to 3)
1. 1. Sieving of Samples Approximately 5 g of pellets of graphene oxide reduced obtained in Preparation Example 2 were pulverized, and using a stainless steel sieve, (i) 0.6 mm or less, (ii) 0.6 to 1.0 mm, (iii). The sample was classified into a particle size range of 4 regions of 1.0 to 2.36 mm and (iv) 2.36 mm or more. In addition, a part of the sample after pulverization was made into an unclassified product without pulverization. The quietness density of the uncrushed unclassified product was 0.283 g / cm 3 .
２．アップフロー型反応器中でのマイクロ波処理
両端の空いた石英製の管型反応器（内径１．３ｃｍ）内に設けられた石英製フィルター上に、約３５０ｍｇの酸化グラフェン還元物の粉末（ほとんどの粒子が粒径１００μｍ未満）、約３５０ｍｇの酸化グラフェン還元物のペレットの粉砕未分級品、又は、１．で得られた酸化グラフェン還元物（ｉ）〜（ｉｖ）約３５０ｍｇ＊を充填した。反応管をマイクロ波発生装置内に垂直方向に設置し、両端にガスラインを接続した後、アルゴンガス（純度９９．９９％）を管下部から毎分１５ｍＬで３０分間流し、ガス置換を行った。その後、アルゴンガスを流しながら、設定出力７００Ｗで試料に５分間マイクロ波を照射した。マイクロ波照射に伴って試料は流動化し、激しい放電現象が観察された。
なお、図１は、アップフロー型反応器中でのマイクロ波処理を示す概略図である。図４〜図７は、それぞれ、アップフロー型反応器中でのマイクロ波照射時における放電現象を示す写真である。図４は、酸化グラフェン還元物の粉末（ほとんどの粒子が粒径１００μｍ未満）を流動化させながらマイクロ波処理したものであり、激しい放電現象により低欠陥化が進んだものの、平均粒径がより大きな酸化グラフェンの還元物を用いた場合と比べると、マイクロ波処理中、マイクロ波が照射可能な領域の外に多くの粉末が飛散し、後述するように低欠陥化の程度も比較的低いものであった。また、図５は、酸化グラフェン還元物（ｉｖ）（平均粒径２．３６ｍｍ以上）を流動化させながらマイクロ波処理したものであり、平均粒径がより小さな酸化グラフェンの還元物を用いた場合と比べると、流動化の程度は低かった。また、マイクロ波処理中に試料が細かく砕けた。
2. 2. Microwave treatment in an upflow reactor Approximately 350 mg of graphene oxide reduced powder (mostly) on a quartz filter provided in a quartz tubular reactor (inner diameter 1.3 cm) with vacant ends. Particle size is less than 100 μm), about 350 mg of graphene oxide reduced pellets are crushed unclassified products, or 1. The graphene oxide reduced products (i) to (iv) obtained in the above (iv) were filled with about 350 mg * . The reaction tube was installed vertically in the microwave generator, gas lines were connected to both ends, and then argon gas (purity 99.99%) was flowed from the bottom of the tube at 15 mL / min for 30 minutes to replace the gas. .. Then, the sample was irradiated with microwaves for 5 minutes at a set output of 700 W while flowing argon gas. The sample fluidized with microwave irradiation, and a violent discharge phenomenon was observed.
Note that FIG. 1 is a schematic view showing microwave processing in an upflow reactor. 4 to 7 are photographs showing a discharge phenomenon during microwave irradiation in an upflow reactor, respectively. FIG. 4 shows a microwave-treated powder of a reduced graphene oxide (most of the particles have a particle size of less than 100 μm), which was treated with microwaves. Although the defects were reduced due to the violent discharge phenomenon, the average particle size was higher. Compared to the case where a large reduced product of graphene oxide is used, a large amount of powder is scattered outside the region where microwaves can be irradiated during microwave treatment, and the degree of defect reduction is relatively low as described later. Met. Further, FIG. 5 shows a microwave treatment while fluidizing a graphene oxide reduced product (iv) (average particle size of 2.36 mm or more), and a case where a reduced product of graphene oxide having a smaller average particle size is used. Compared with, the degree of liquidation was low. In addition, the sample was finely crushed during the microwave treatment.
＊試料仕込み量：（ｉ）３６０．０ｍｇ、（ｉｉ）３６１．０ｍｇ、（ｉｉｉ）３３９．７ｍｇ、（ｉｖ）３４９．１ｍｇ * Sample preparation amount: (i) 360.0 mg, (ii) 361.0 mg, (iii) 339.7 mg, (iv) 349.1 mg
３．ダウンフロー型反応器中でのマイクロ波処理
一端が閉じた石英製の管型反応器（外径１インチ）の底部に約５００ｍｇの酸化グラフェン還元物の粉末を充填した。反応器を垂直方向に固定し、上端に接続したガスラインから真空ポンプで系内を排気した後、アルゴンガス（純度９９．９９％）で常圧まで戻す操作を３回繰り返し反応器内のガス置換を行った。ガス置換後、反応器上端からアルゴンガスを毎分１００ｍＬで流しながら、反応管をマイクロ波発生装置内に垂直方向に設置し、設定出力７００Ｗで試料に５分間マイクロ波処理を行った。マイクロ波照射に伴って試料の赤熱が観察されたが、試料の流動化は観察されなかった。
なお、図２は、ダウンフロー型反応器中でのマイクロ波処理を示す概略図である。図８は、ダウンフロー型反応器中でのマイクロ波照射時における試料の赤熱の様子を示す写真である。
3. 3. Microwave treatment in a downflow reactor The bottom of a quartz tubular reactor (outer diameter 1 inch) with one end closed was filled with about 500 mg of graphene oxide reduced powder. After fixing the reactor in the vertical direction and exhausting the inside of the system with a vacuum pump from the gas line connected to the upper end, the operation of returning to normal pressure with argon gas (purity 99.99%) is repeated 3 times to gas in the reactor. Substitution was performed. After gas replacement, the reaction tube was placed vertically in the microwave generator while flowing argon gas at 100 mL / min from the upper end of the reactor, and the sample was microwave-treated at a set output of 700 W for 5 minutes. Red heat of the sample was observed with microwave irradiation, but fluidization of the sample was not observed.
Note that FIG. 2 is a schematic view showing microwave processing in a downflow reactor. FIG. 8 is a photograph showing the state of redness of the sample at the time of microwave irradiation in the downflow type reactor.
図３は、実施例の低欠陥化炭素材料、及び、比較例の炭素材料の、ラマンスペクトルを示すグラフである。
図３に示す（１）〜（９）のスペクトルは、それぞれ、以下の通りである。
（１）酸化グラフェン還元物の粉末（ほとんどの粒子が粒径１００μｍ未満のペレット未成型品）（比較例１）
（２）（１）の酸化グラフェン還元物の粉末をダウンフロー型反応器中で５分間流動化させることなくマイクロ波処理したもの（比較例２）
（３）（１）の酸化グラフェン還元物の粉末をアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例１）
（４）酸化グラフェン還元物のペレット（比較例３）
（５）（４）の酸化グラフェン還元物のペレットを粉砕し、分級することなくアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例２）
（６）（４）の酸化グラフェン還元物のペレットを粉砕、分級して得た粒径範囲２．３６ｍｍ以上のものをアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例３）
（７）（４）の酸化グラフェン還元物のペレットを粉砕、分級して得た粒径範囲１．０〜２．３６ｍｍのものをアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例４）
（８）（４）の酸化グラフェン還元物のペレットを粉砕、分級して得た粒径範囲０．６〜１．０ｍｍのものをアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例５）
（９）（４）の酸化グラフェン還元物のペレットを粉砕、分級して得た粒径範囲０．６ｍｍ以下のものをアップフロー型反応器中で５分間流動化させながらマイクロ波処理したもの（実施例６）
FIG. 3 is a graph showing Raman spectra of the low defect carbon material of the example and the carbon material of the comparative example.
The spectra of (1) to (9) shown in FIG. 3 are as follows.
(1) Graphene oxide reduced powder (most of the particles are unmolded pellets with a particle size of less than 100 μm) (Comparative Example 1)
(2) The powder of the graphene oxide reduced product of (1) was microwave-treated in a downflow reactor for 5 minutes without being fluidized (Comparative Example 2).
(3) The powder of the graphene oxide reduced product of (1) was microwave-treated while being fluidized in an upflow reactor for 5 minutes (Example 1).
(4) Pellet of reduced graphene oxide (Comparative Example 3)
(5) The pellets of the graphene oxide reduced product of (4) were pulverized and microwave-treated while being fluidized in an upflow reactor for 5 minutes without classification (Example 2).
(6) Pellets of the graphene oxide reduced product of (4) were crushed and classified, and those having a particle size range of 2.36 mm or more were subjected to microwave treatment while being fluidized in an upflow type reactor for 5 minutes ( Example 3)
(7) The pellets of the graphene oxide reduced product of (4) were pulverized and classified, and the particles having a particle size range of 1.0 to 2.36 mm were subjected to microwave treatment while being fluidized in an upflow reactor for 5 minutes. (Example 4)
(8) The pellets of the graphene oxide reduced product of (4) were pulverized and classified, and the particles having a particle size range of 0.6 to 1.0 mm were subjected to microwave treatment while being fluidized in an upflow reactor for 5 minutes. (Example 5)
(9) The pellets of the graphene oxide reduced product of (4) were pulverized and classified, and the particles having a particle size range of 0.6 mm or less were subjected to microwave treatment while being fluidized in an upflow reactor for 5 minutes ( Example 6)
＜最大流動かさ密度＞
最大流動かさ密度は、上述したように、マイクロ波照射開始後の試料体積の最大値に対する試料の質量から算出され、マイクロ波照射開始後の試料体積は、マイクロ波照射開始後に試料が流動している空間の高さ、幅（縦幅・横幅等）、及び、形状にもとづいて算出される。実施例では、試料が流動している空間の幅は管型反応器内径と同一視でき、試料が流動している空間の形状は管型反応器の内部空間の形状（円柱状）と同一視できるため、マイクロ波照射開始後の試料体積は管型反応器内径と試料が舞った高さから算出した。試料が舞った高さは、試料を流動化させながらのマイクロ波照射開始から照射終了までの映像から読み取った。
<Maximum flow bulk density>
As described above, the maximum flow bulk density is calculated from the mass of the sample with respect to the maximum value of the sample volume after the start of microwave irradiation, and the sample volume after the start of microwave irradiation is such that the sample flows after the start of microwave irradiation. It is calculated based on the height, width (length, width, etc.) and shape of the existing space. In the embodiment, the width of the space in which the sample is flowing can be equated with the inner diameter of the tubular reactor, and the shape of the space in which the sample is flowing is equated with the shape of the internal space (cylindrical) of the tubular reactor. Therefore, the sample volume after the start of microwave irradiation was calculated from the inner diameter of the tubular reactor and the height at which the sample fluttered. The height at which the sample fluttered was read from the images from the start of microwave irradiation to the end of irradiation while the sample was fluidized.
アップフロー型反応器中で用いた管型反応器の内径は、１．３ｃｍであった。
また、実施例１（ほとんどの粒子が粒径１００μｍ未満）において、試料が舞った高さの最大値は１０．９ｃｍ以上であり、マイクロ波が照射可能な領域外への多くの粉末の飛散が認められた。
実施例３（平均粒径２．３６ｍｍ以上）において、試料が舞った高さの最大値は１．３ｃｍであり、実施例４（平均粒径１．０〜２．３６ｍｍ）において、試料が舞った高さの最大値は５．０ｃｍであり、実施例６（平均粒径０．６ｍｍ以下）において、試料が舞った高さの最大値は８．６ｃｍであった。以上から、マイクロ波照射開始後の試料体積の最大値は、実施例３では１．７２ｃｍ３であり、実施例４では６．６３ｃｍ３であり、実施例６では１１．４１ｃｍ３であった。
The inner diameter of the tubular reactor used in the upflow reactor was 1.3 cm.
Further, in Example 1 (most particles have a particle size of less than 100 μm), the maximum value of the height at which the sample flew is 10.9 cm or more, and many powders are scattered outside the region where microwaves can be irradiated. Admitted.
In Example 3 (average particle size 2.36 mm or more), the maximum value of the height at which the sample flew was 1.3 cm, and in Example 4 (average particle size 1.0 to 2.36 mm), the sample flew. The maximum value of the height was 5.0 cm, and in Example 6 (average particle size of 0.6 mm or less), the maximum value of the height at which the sample fluttered was 8.6 cm. From the above, the maximum value of the sample volume after initiation microwave irradiation is 1.72Cm 3 In Example 3, a 6.63Cm 3 Example 4 was 11.41Cm 3 in Example 6.
最大流動かさ密度を算出すると、実施例３では０．２０３ｇ／ｃｍ３であり、実施例４では０．０５１ｇ／ｃｍ３であり、実施例６では０．０３２ｇ／ｃｍ３であった。
なお、図４〜図７は、それぞれ、実施例１、実施例３、実施例４、実施例６でのマイクロ波照射時における放電現象を示す写真である。図８は、比較例２でのマイクロ波照射時における試料の赤熱の様子を示す写真である。
After calculating the maximum flow bulk density is 0.203 g / cm 3 In Example 3, was 0.051 g / cm 3 in Example 4, was 0.032 g / cm 3 in Example 6.
4 to 7 are photographs showing the discharge phenomenon at the time of microwave irradiation in Example 1, Example 3, Example 4, and Example 6, respectively. FIG. 8 is a photograph showing the state of redness of the sample at the time of microwave irradiation in Comparative Example 2.
＜ラマンスペクトルによる低欠陥化進行度の確認＞
ラマンスペクトルにおけるＧバンドのピーク強度に対するＤバンドのピーク強度の比（ＩＤ／ＩＧ）を算出すると、以下の通りである。
<Confirmation of progress of low defect by Raman spectrum>
The ratio ( ID / IG ) of the peak intensity of the D band to the peak intensity of the G band in the Raman spectrum is calculated as follows.
酸化グラフェン還元物の粉末（ほとんどの粒子が粒径１００μｍ未満）の場合（実施例１、比較例１、２）
比較例１の酸化グラフェン還元物の粉末のＩＤ／ＩＧは１．６であった。これをダウンフロー型反応器中で５分間流動化させることなくマイクロ波処理した比較例２の酸化グラフェン還元物の粉末のＩＤ／ＩＧは１．４であった。一方、比較例１の酸化グラフェン還元物をアップフロー型反応器中で５分間流動化しながらマイクロ波処理した実施例１の酸化グラフェン還元物の粉末のＩＤ／ＩＧは１．３であり、マイクロ波が照射可能な領域の外に多くの粉末が飛散していたにも関わらず、低欠陥化がより進んでいた。
In the case of graphene oxide reduced powder (most of the particles have a particle size of less than 100 μm) (Example 1, Comparative Examples 1 and 2)
I D / I G of powder reduced graphene oxide of Comparative Example 1 was 1.6. I D / I G of powder reduced graphene oxide of Comparative Example 2 was treated without microwaves be 5 minutes fluidized this downflow type reactor was 1.4. On the other hand, I D / I G of powder reduced graphene oxide and reduced graphene oxide of Example 1 was microwaved with 5 minutes fluidized in upflow reactors of Comparative Example 1 is 1.3, Despite the fact that a large amount of powder was scattered outside the region where microwaves could be irradiated, the number of defects was further reduced.
酸化グラフェン還元物のペレットの場合（実施例２〜６、比較例３）
比較例３の酸化グラフェン還元物のペレットのＩＤ／ＩＧは１．６であった。これを粉砕し、分級はしないでアップフロー型反応器中で５分間流動化しながらマイクロ波処理した実施例２の酸化グラフェン還元物のＩＤ／ＩＧは０．６４であり、低欠陥化が非常に進んでいた。った。
また比較例３の酸化グラフェン還元物を粉砕、分級し、平均粒径２．３６ｍｍ以上のものをアップフロー型反応器中で５分間マイクロ波処理した実施例３の酸化グラフェン還元物のＩＤ／ＩＧは０．９５であり、低欠陥化が充分に進んでいた。
更に、平均粒径１．０〜２．３６ｍｍのものをアップフロー型反応器中で５分間マイクロ波処理した実施例４の酸化グラフェン還元物のＩＤ／ＩＧは０．７５であった。更に、平均粒径０．６〜１．０ｍｍのものをアップフロー型反応器中で５分間マイクロ波処理した実施例５の酸化グラフェン還元物のＩＤ／ＩＧは０．４６であり、平均粒径０．６ｍｍ以下のものをアップフロー型反応器中で５分間マイクロ波処理した実施例６の酸化グラフェン還元物のＩＤ／ＩＧは０．４７であり、低欠陥化が顕著なものであった。
In the case of pellets of reduced graphene oxide (Examples 2 to 6, Comparative Example 3)
I D / I G of the pellets reduced graphene oxide of Comparative Example 3 was 1.6. It was ground, I D / I G of the classifier reduced graphene oxide of Example 2 was microwaved with 5 minutes fluidized in upflow reactor without is 0.64, low defect reduction is It was very advanced. It was.
The pulverized reduced graphene oxide of Comparative Example 3, was classified, the average particle size reduced graphene oxide of Example 3 2.36mm or more ones in upflow reactors was treated 5 min microwave I D / I G is 0.95, low defect reduction was progressed sufficiently.
Furthermore, I D / I G of reduced graphene oxide of an average particle diameter in Example was treated for 5 minutes in a microwave at up-flow reactor in those 1.0～2.36Mm 4 was 0.75. Furthermore, I D / I G of the average particle size reduced graphene oxide of Example 5 was microwaved for 5 minutes at up-flow reactor in those 0.6~1.0mm is 0.46, the average I D / I G of reduced graphene oxide of example 6 was treated as a particle diameter 0.6mm or less in an upflow reactor 5 minutes microwave is 0.47, of lower defect reduction is significant Met.
図９は、実施例の低欠陥化炭素材料、及び、比較例の炭素材料の、熱重量測定を評価した結果を示すグラフである。なお、熱重量測定における測定試料量は５ｍｇとした。
ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射することで得られる低欠陥化炭素材料は、耐酸化性に優れることが分かる。特に、平均粒径が１．０ｍｍ以下の炭素材料を流動化しながら、該炭素材料にマイクロ波を照射して得られた実施例５、６の低欠陥化炭素材料において、耐酸化性が他の試料よりも高いことが分かる。
FIG. 9 is a graph showing the results of evaluating the thermogravimetric measurement of the low-defect carbon material of the example and the carbon material of the comparative example. The amount of the measurement sample in the thermogravimetric analysis was 5 mg.
It can be seen that the defect-reduced carbon material obtained by irradiating the carbon material with microwaves while fluidizing the carbon material having a G band peak in the Raman spectrum is excellent in oxidation resistance. In particular, the low-defect carbon materials of Examples 5 and 6 obtained by irradiating the carbon material with microwaves while fluidizing the carbon material having an average particle size of 1.0 mm or less have other oxidation resistance. It can be seen that it is higher than the sample.
以上の結果から、ラマンスペクトルにおいてＧバンドのピークを有する炭素材料を流動化しながら、該炭素材料にマイクロ波を照射することで、炭素材料を好適に低欠陥化できることが確認された。 From the above results, it was confirmed that the carbon material can be suitably reduced in defects by irradiating the carbon material with microwaves while fluidizing the carbon material having a G band peak in the Raman spectrum.
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