JP5391216B2 - Method for producing exfoliated graphite compound and exfoliated graphite compound - Google Patents

Method for producing exfoliated graphite compound and exfoliated graphite compound Download PDF

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JP5391216B2
JP5391216B2 JP2011031279A JP2011031279A JP5391216B2 JP 5391216 B2 JP5391216 B2 JP 5391216B2 JP 2011031279 A JP2011031279 A JP 2011031279A JP 2011031279 A JP2011031279 A JP 2011031279A JP 5391216 B2 JP5391216 B2 JP 5391216B2
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克典 高橋
直之 永谷
大輔 向畑
浩司 谷口
延彦 乾
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Sekisui Chemical Co Ltd
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本発明は、薄片化黒鉛化合物の製造方法に関する。 The present invention relates to the production how of exfoliated graphite compound.

近年、炭素骨格を有し且つ形状異方性の高い物質として、黒鉛をその層面間で剥離し、層面(グラフェン)の重なりが数十層以下になるまで薄片化した薄片化黒鉛化合物が注目されており、薄片化黒鉛化合物は非常に大きな表面積を有するため、樹脂などと複合化すると、少量の薄片化黒鉛化合物の添加で各種機能が発現すると期待されている。   In recent years, exfoliated graphite compounds, which have a carbon skeleton and have high shape anisotropy, are exfoliated until the graphite layer is exfoliated between the layer surfaces and the layer surface (graphene) overlaps dozens of layers or less. Since exfoliated graphite compounds have a very large surface area, when combined with a resin or the like, it is expected that various functions will be manifested by the addition of a small amount of exfoliated graphite compounds.

上記薄片化黒鉛化合物の製造方法としては、例えば、特許文献1に、硫酸・硝酸及び過マンガン酸カリウムを用いて酸化させた黒鉛層間化合物を精製し、遠心分離した後、上澄みを除去することによって薄片化酸化黒鉛が得られることが提案されている。   As a method for producing the exfoliated graphite compound, for example, in Patent Document 1, a graphite intercalation compound oxidized using sulfuric acid / nitric acid and potassium permanganate is purified, centrifuged, and then the supernatant is removed. It has been proposed to obtain exfoliated graphite oxide.

又、特許文献2には、硫酸、硝酸、塩素酸などを用いて酸化させた黒鉛層間化合物を2000℃/分の急速加熱により剥離し、剥離された酸化黒鉛を得ることが提案されている。そして、加熱時に不活性雰囲気下におくことにより、酸化黒鉛が部分的に還元されることが記載されている。   Patent Document 2 proposes to exfoliate graphite intercalation compounds oxidized using sulfuric acid, nitric acid, chloric acid or the like by rapid heating at 2000 ° C./min to obtain exfoliated graphite oxide. It is described that graphite oxide is partially reduced by placing it in an inert atmosphere during heating.

しかしながら、上記製造方法では、薄片化黒鉛化合物を得るために黒鉛層間化合物を酸化させる必要があり、薄片化酸化黒鉛の製造に時間を要するという問題点を有している。又、黒鉛層間化合物を酸化させた上で黒鉛層間化合物の剥離を行っていることから、黒鉛の層面の酸化が不充分な部分においては、黒鉛の層面間への化合物の挿入が不充分になるという問題があり、黒鉛層間化合物の酸化状態が、得られる薄片化酸化黒鉛の形状に影響を及ぼすという問題点を有している。   However, the above production method has a problem that it is necessary to oxidize the graphite intercalation compound in order to obtain the exfoliated graphite compound, and it takes time to produce the exfoliated graphite oxide. In addition, since the graphite intercalation compound is peeled off after oxidizing the graphite intercalation compound, the insertion of the compound between the graphite layer surfaces becomes insufficient in the portion where the oxidation of the graphite layer surface is insufficient. There is a problem that the oxidation state of the graphite intercalation compound affects the shape of the exfoliated graphite oxide obtained.

特開2002−53313号公報JP 2002-53313 A 特表2009−511415号公報Special table 2009-511415 gazette

本発明は、薄片化黒鉛化合物を容易に製造することができる薄片化黒鉛化合物の製造方法を提供する。 The present invention provides a manufacturing how the exfoliated graphite compound which can be easily manufactured exfoliated graphite compound.

本発明の薄片化黒鉛化合物の製造方法は、黒鉛化合物を高圧流体に接触させた後、上記高圧流体に加わっている圧力を減圧することにより、上記黒鉛化合物を薄片化することを特徴とする。   The method for producing the exfoliated graphite compound of the present invention is characterized in that the graphite compound is exfoliated by bringing the graphite compound into contact with a high-pressure fluid and then reducing the pressure applied to the high-pressure fluid.

本発明において用いられる黒鉛化合物としては、黒鉛、黒鉛層間化合物、及び膨張黒鉛の何れであってもよい。なお、黒鉛に官能基が化学的に結合してしても、或いは、黒鉛に官能基が弱い相互作用により疑似的に結合していてもよい。   The graphite compound used in the present invention may be any of graphite, graphite intercalation compounds, and expanded graphite. Note that a functional group may be chemically bonded to graphite, or a functional group may be artificially bonded to graphite due to weak interaction.

黒鉛としては、粒子全体で単一の多層構造を有する黒鉛が好ましく、例えば、天然黒鉛、キッシュ黒鉛、高配向性熱分解黒鉛などが挙げられる。天然黒鉛とキッシュ黒鉛は、各層面(基本層)が略単一の方位を有する単独の結晶であり、高配向性熱分解黒鉛の各層面(基本層)は異なる方位を有する多数の小さな結晶の集合体である。   As the graphite, graphite having a single multilayer structure as a whole is preferable, and examples thereof include natural graphite, quiche graphite, and highly oriented pyrolytic graphite. Natural graphite and quiche graphite are single crystals in which each layer surface (basic layer) has a substantially single orientation, and each layer surface (basic layer) of high-orientation pyrolytic graphite has a large number of small crystals having different orientations. It is an aggregate.

黒鉛層間化合物は、上記黒鉛の層面間にインターカレーターを挿入することによって形成されている。黒鉛層間化合物における黒鉛の層面間に挿入されるインターカレーターとしては、特に限定されず、例えば、酸、酸化剤、金属、金属塩、気体、ハロゲン化合物などが挙げられる。インターカレーターは単独で用いられても二種以上が併用されてもよい。   The graphite intercalation compound is formed by inserting an intercalator between the graphite layer surfaces. The intercalator inserted between the graphite layer surfaces in the graphite intercalation compound is not particularly limited, and examples thereof include acids, oxidizing agents, metals, metal salts, gases, and halogen compounds. An intercalator may be used independently or 2 or more types may be used together.

酸としては、例えば、硝酸、塩酸、硫酸、カルボン酸、クロム酸、リン酸、ヨウ素酸などが挙げられる。酸化剤としては、例えば、過マンガン酸カリウム、過酸化水素、塩素酸カリウム、臭素酸ナトリウム、次亜塩素酸ナトリウムなどが挙げられる。金属としては、例えば、カリウム、ナトリウムなどが挙げられる。金属塩としては、例えば、塩化銅、塩化鉄、塩化銀、塩化アルミニウムなどが挙げられる。気体としては、例えば、水素、塩素などが挙げられる。ハロゲン化合物としては、例えば、塩化ヨウ素、塩化臭素、臭化ヨウ素、フッ化ヨウ素、フッ化臭素、フッ化塩素、フッ素、塩素、塩化アルミニウムなどが挙げられる。   Examples of the acid include nitric acid, hydrochloric acid, sulfuric acid, carboxylic acid, chromic acid, phosphoric acid, iodic acid and the like. Examples of the oxidizing agent include potassium permanganate, hydrogen peroxide, potassium chlorate, sodium bromate, and sodium hypochlorite. Examples of the metal include potassium and sodium. Examples of the metal salt include copper chloride, iron chloride, silver chloride, and aluminum chloride. Examples of the gas include hydrogen and chlorine. Examples of the halogen compound include iodine chloride, bromine chloride, iodine bromide, iodine fluoride, bromine fluoride, chlorine fluoride, fluorine, chlorine, and aluminum chloride.

黒鉛の層面間にインターカレーターを挿入して黒鉛層間化合物を製造する方法としては、公知の方法を採用することができ、例えば、黒鉛をインターカレーターの溶液に分散させて、分散液中において黒鉛とインターカレーターとを反応させて黒鉛層間化合物を製造する方法、黒鉛と気体状のインターカレーターとを高圧下にて反応させて黒鉛層間化合物を製造する方法、酸化剤を用いてHummers−Offeman法によって黒鉛層間化合物を製造する方法などが挙げられ、酸化剤を用いてHummers−Offeman法によって黒鉛層間化合物を製造する方法が好ましい。   As a method for producing a graphite intercalation compound by inserting an intercalator between graphite layer surfaces, a known method can be adopted. For example, graphite is dispersed in an intercalator solution, and graphite and A method for producing a graphite intercalation compound by reacting with an intercalator, a method for producing a graphite intercalation compound by reacting graphite and a gaseous intercalator under high pressure, and a graphite by a Hummers-Offeman method using an oxidizing agent. The method of manufacturing an intercalation compound etc. are mentioned, The method of manufacturing a graphite intercalation compound by the Hummers-Offeman method using an oxidizing agent is preferred.

黒鉛層間化合物は、粉砕などの物理的応力を加えて粉砕し、或いは、超音波を照射するなどして黒鉛層間化合物の層面をある程度剥離させておくことが好ましい。   The graphite intercalation compound is preferably pulverized by applying physical stress such as pulverization, or the layer surface of the graphite intercalation compound is separated to some extent by irradiating ultrasonic waves.

膨張黒鉛は、上記黒鉛層間化合物を加熱するなどして層面間の結合を切断し、上記黒鉛層間化合物の層面間の間隔を広げることによって得ることができる。   Expanded graphite can be obtained by, for example, heating the graphite intercalation compound to break the bond between the layer surfaces and increasing the spacing between the layer surfaces of the graphite intercalation compound.

黒鉛化合物において、レーザー光回折法により粒度分布を測定した場合に50%体積平均径として得られる値は、小さいと、黒鉛化合物を薄片化して得られる薄片化黒鉛化合物において異方性が得られないことがあり、或いは、黒鉛化合物を薄片化して得られる薄片化黒鉛化合物を樹脂と混合して複合体とした場合に複合体の強度などが低下することがあり、大きいと、黒鉛化合物が凝集した状態であり、黒鉛化合物の薄片化に長時間を要することがあるので、5〜50μmが好ましい。   In a graphite compound, when the particle size distribution is measured by a laser light diffraction method, if the value obtained as the 50% volume average diameter is small, anisotropy cannot be obtained in the exfoliated graphite compound obtained by exfoliating the graphite compound. In some cases, when a exfoliated graphite compound obtained by exfoliating a graphite compound is mixed with a resin to form a composite, the strength of the composite may decrease. Since it is a state and it may take a long time to make the graphite compound thin, 5 to 50 μm is preferable.

なお、レーザー光回折法により粒度分布を測定した場合に50%体積平均径として得られる値が20μm未満である黒鉛化合物は、例えば、SECカーボン社から商品名「SNO−15」などのSNOシリーズにて、中越黒鉛工業所から商品名「CX−3000」にて、伊藤黒鉛社からCNP−シリーズにて、XGSience社から商品名「XGnP−5」にて市販されている。   In addition, when the particle size distribution is measured by a laser light diffraction method, a graphite compound having a value obtained as a 50% volume average diameter of less than 20 μm is, for example, an SNO series such as a trade name “SNO-15” from SEC Carbon Corporation. These products are commercially available from Chuetsu Graphite Industries Co., Ltd. under the trade name “CX-3000”, from Ito Graphite Co. in the CNP-series, and from XGSience Corporation under the trade name “XGnP-5”.

上記黒鉛化合物を高圧流体に接触させた後、上記高圧流体に加わっている圧力を減圧することにより、黒鉛化合物を薄片化して薄片化黒鉛化合物を製造する。高圧流体、特に、亜臨界流体及び超臨界流体は、黒鉛化合物の層面間に進入しやすい。このような高圧流体を黒鉛化合物の層面間に進入させた上で高圧流体に加わっている圧力を減圧することにより、黒鉛化合物の層面間に進入した高圧流体が膨張して層面間に存在するファンデルワールス結合を切断し、黒鉛化合物の層面同士を離間させて、黒鉛化合物の層面を剥離して薄片化黒鉛化合物を製造することができる。   After the graphite compound is brought into contact with the high-pressure fluid, the pressure applied to the high-pressure fluid is reduced, so that the graphite compound is exfoliated to produce a exfoliated graphite compound. High-pressure fluids, particularly subcritical fluids and supercritical fluids, tend to enter between the layer surfaces of graphite compounds. A fan in which such high-pressure fluid enters between the layer surfaces of the graphite compound and the pressure applied to the high-pressure fluid is reduced to expand the high-pressure fluid that has entered between the layer surfaces of the graphite compound and exists between the layer surfaces. It is possible to produce a exfoliated graphite compound by cutting Delaware bonds, separating the graphite compound layer surfaces, and peeling the graphite compound layer surfaces.

高圧流体は亜臨界流体又は超臨界流体であるが、超臨界流体がより好ましい。 The high-pressure fluid is a subcritical fluid or a supercritical fluid , but a supercritical fluid is more preferable.

なお、超臨界流体とは、臨界点における温度(臨界温度Tc)以上の温度とし且つ臨界点における圧力(臨界圧力Pc)以上の圧力とした状態の流体をいう。亜臨界流体とは、臨界点近傍の、臨界温度Tcよりもやや温度が低い状態又は臨界圧力Pcよりもやや圧力が低い状態の流体をいう。亜臨界流体は、流体の温度Tと臨界温度Tcとの比(T/Tc)が0.9以上で且つ1未満であり、且つ流体の圧力Pを臨界圧力Pc以上とした状態の流体、又は流体の温度を臨界温度Tc以上とし、且つ流体の圧力Pと臨界圧力Pcとの比(P/Pc)が0.9以上で且つ1未満とした状態の流体であるのが好ましい。   The supercritical fluid is a fluid in a state where the temperature is equal to or higher than the temperature at the critical point (critical temperature Tc) and the pressure is equal to or higher than the pressure at the critical point (critical pressure Pc). The subcritical fluid refers to a fluid in the vicinity of the critical point and having a temperature slightly lower than the critical temperature Tc or a pressure slightly lower than the critical pressure Pc. The subcritical fluid is a fluid in which the ratio (T / Tc) of the fluid temperature T to the critical temperature Tc is 0.9 or more and less than 1, and the fluid pressure P is set to the critical pressure Pc or more, or The fluid is preferably in a state where the temperature of the fluid is not less than the critical temperature Tc and the ratio (P / Pc) of the fluid pressure P to the critical pressure Pc is not less than 0.9 and less than 1.

流体は流動性を有しておればよく、常温で且つ常圧下にて液体状態の流体を含み、常温で且つ常圧下にて液体状態の流体と常温で且つ常圧下にて気体状態の流体とを含んでいることが好ましいThe fluid only needs to have fluidity, and includes a fluid in a liquid state at normal temperature and normal pressure, a fluid in a liquid state at normal temperature and normal pressure, and a fluid in a gas state at normal temperature and normal pressure. It is preferable that it contains .

常温で且つ常圧下にて液体状態の流体としては、例えば、水、ヘキサン、ヘプタン、シクロヘキサン、ベンゼン、トルエン、キシレン、及びジクロロベンゼンなどの炭化水素類、ジエチルエーテル、ジブチルエーテル、テトラヒドロフラン、及びジオキサンなどのエーテル類、酢酸エチル、及び酢酸ブチルなどのエステル類、アセトン、メチルエチルケトン、メチルイソブチルケトン、及びN−メチルピロリドンなどのケトン類、メタノール、エタノール、及びイソプロピルアルコールなどのアルコール類、ジメチルスルホキシド、N,N′−ジメチルホルムアミド、N,N′−ジメチルアセトアミド、及びN−メチル−2−ピロリドンなどが挙げられる。なかでも、水、メタノール、エタノール、及びイソプロピルアルコールなどのアルコール類などの流体は、これに圧力を加えて高圧流体とした際に、黒鉛化合物の表面状態に関わらず黒鉛化合物の層面間に進入し易く、黒鉛化合物の薄片化を容易に行うことができるため、好ましく用いられる。   Examples of fluids that are in a liquid state at normal temperature and normal pressure include hydrocarbons such as water, hexane, heptane, cyclohexane, benzene, toluene, xylene, and dichlorobenzene, diethyl ether, dibutyl ether, tetrahydrofuran, and dioxane. Ethers, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and N-methyl pyrrolidone, alcohols such as methanol, ethanol, and isopropyl alcohol, dimethyl sulfoxide, N, N'-dimethylformamide, N, N'-dimethylacetamide, N-methyl-2-pyrrolidone and the like can be mentioned. Among them, fluids such as water, methanol, ethanol, and alcohols such as isopropyl alcohol, when pressure is applied to the fluid, enter between the graphite compound layer surfaces regardless of the surface condition of the graphite compound. The graphite compound is preferably used because it is easy to make the graphite compound thin.

常温で且つ常圧下にて気体状態の流体としては、例えば、窒素、亜酸化窒素、二酸化炭素、クロロジフルオロメタン、ジクロロトリフルオロエタンなどのクロロフルオロカーボン、ヒドロクロロフルオロカーボン、n−ブタン、プロパン、エタンなどの低分子量アルカン、エチレンなどの低分子量アルケン、ジメチルアミン、エチルアミン、トリエチルアミン、アニリン、及びピリジン、アンモニア、酸素、ヘリウム、アルゴンなどが挙げられる。このような常温で且つ常圧下にて気体状態の流体は、これを用いて製造した薄片化黒鉛化合物の回収を容易に行うことができる。すなわち、常温で且つ常圧下にて気体状態の流体に圧力を加えて高圧流体とし、この高圧流体を黒鉛化合物に接触させて薄片化黒鉛化合物を製造した後に、反応系内の圧力を開放することによって上記流体を速やかに気化させて反応系外へ排出できるため、常温で且つ常圧下にて気体状態の流体によれば反応系内に残っている薄片化黒鉛化合物の回収を容易に行うことが可能となる。   Examples of the fluid in a gaseous state at normal temperature and normal pressure include, for example, chlorofluorocarbons such as nitrogen, nitrous oxide, carbon dioxide, chlorodifluoromethane, and dichlorotrifluoroethane, hydrochlorofluorocarbons, n-butane, propane, and ethane. Low molecular weight alkanes, low molecular weight alkenes such as ethylene, dimethylamine, ethylamine, triethylamine, aniline, and pyridine, ammonia, oxygen, helium, argon, and the like. Such a fluid in a gaseous state at normal temperature and normal pressure can easily recover the exfoliated graphite compound produced using the fluid. That is, pressure is applied to a fluid in a gaseous state at normal temperature and normal pressure to form a high-pressure fluid, and after the exfoliated graphite compound is produced by bringing this high-pressure fluid into contact with the graphite compound, the pressure in the reaction system is released. The above fluid can be quickly vaporized and discharged out of the reaction system, so that the exfoliated graphite compound remaining in the reaction system can be easily recovered with a fluid in a gaseous state at room temperature and under normal pressure. It becomes possible.

常温で且つ常圧下にて気体状態の流体としては、比較的低温、低圧で超臨界流体とすることができ且つ黒鉛化合物の各層面の表面状態に影響を及ぼさないことから、二酸化炭素、窒素が好ましい。   As a fluid in a gaseous state at normal temperature and normal pressure, it can be a supercritical fluid at a relatively low temperature and low pressure and does not affect the surface state of each layer surface of the graphite compound. preferable.

上記流体は、一種のみを用いてもよく、二種以上を併用してもよい。二種以上の流体を用いる場合、常温で且つ常圧下にて液体状態の流体と、常温で且つ常圧下にて気体状態の流体とを用いるのが好ましく、水又はアルコール類と、二酸化炭素とを用いるのがより好ましい。これらの流体を組合せて用いることにより、比較的低温、低圧で超臨界流体とすることができると共に、得られる超臨界流体は黒鉛化合物の表面状態に関わらず黒鉛化合物の層面間に進入し易く、黒鉛化合物の薄片化を容易に行うことができる。   The said fluid may use only 1 type and may use 2 or more types together. When two or more fluids are used, it is preferable to use a fluid in a liquid state at normal temperature and normal pressure, and a fluid in a gas state at normal temperature and normal pressure. Water or alcohols and carbon dioxide are used. More preferably it is used. By using these fluids in combination, it can be made a supercritical fluid at a relatively low temperature and low pressure, and the resulting supercritical fluid can easily enter between the layers of the graphite compound regardless of the surface state of the graphite compound. Thinning of the graphite compound can be performed easily.

高圧流体に加えられる圧力としては、低いと、高圧流体が黒鉛化合物の層面間に進入し難くなり、黒鉛化合物の薄片化が円滑に進行しない虞れがあるので、0.5MPa以上が好ましく、5MPa以上がより好ましく、臨界点における圧力(臨界圧力Pc)以上の圧力が特に好ましい。また、高圧流体に加えられる圧力は、高くても、黒鉛化合物の薄片化の効果に変化はないので、100MPa以下が好ましく、80MPa以下がより好ましく、50MPa以下が特に好ましい。   If the pressure applied to the high pressure fluid is low, the high pressure fluid is unlikely to enter between the layer surfaces of the graphite compound, and the flaking of the graphite compound may not proceed smoothly. The above is more preferable, and a pressure equal to or higher than the pressure at the critical point (critical pressure Pc) is particularly preferable. Further, even if the pressure applied to the high-pressure fluid is high, there is no change in the effect of thinning the graphite compound, so it is preferably 100 MPa or less, more preferably 80 MPa or less, and particularly preferably 50 MPa or less.

黒鉛化合物を高圧流体に接触させる方法としては、特に限定されない。常温で且つ常圧下にて液体状態の流体に圧力を加えることにより高圧流体とする場合には、例えば、常温で且つ常圧下にて液体状態の流体中に黒鉛化合物を供給し分散させて混合体を作製し、この混合体に、好ましくは混合体を加熱しながら、圧力を加えて高圧流体とすると共に、黒鉛化合物を高圧流体に接触させる方法、常温で且つ常圧下にて液体状態の流体を、好ましくは加熱しながら、加圧して高圧流体とした上で、この高圧流体内に黒鉛化合物を供給、分散させて黒鉛化合物を高圧流体に接触させる方法などが挙げられる。高圧流体を加熱する場合、高圧流体を20〜600℃に加熱することが好ましく、30〜400℃に加熱することがより好ましく、臨界点における温度(臨界温度Tc)以上の温度に高圧流体を加熱することが特に好ましい。高圧流体の加熱温度を上記範囲内とすることにより高圧流体を黒鉛化合物の層面間に十分に進入させることができる。   The method for bringing the graphite compound into contact with the high-pressure fluid is not particularly limited. When pressure is applied to a fluid in a liquid state at normal temperature and normal pressure, for example, a graphite compound is supplied and dispersed in the liquid fluid at normal temperature and normal pressure. In this method, preferably, while heating the mixture, pressure is applied to form a high-pressure fluid and a graphite compound is brought into contact with the high-pressure fluid. A fluid in a liquid state at normal temperature and normal pressure is prepared. The method may be a method in which a high pressure fluid is pressurized with heating, and a graphite compound is supplied and dispersed in the high pressure fluid to bring the graphite compound into contact with the high pressure fluid. When heating the high-pressure fluid, the high-pressure fluid is preferably heated to 20 to 600 ° C., more preferably 30 to 400 ° C., and the high-pressure fluid is heated to a temperature equal to or higher than the temperature at the critical point (critical temperature Tc). It is particularly preferable to do this. By setting the heating temperature of the high pressure fluid within the above range, the high pressure fluid can sufficiently enter between the layer surfaces of the graphite compound.

常温で且つ常圧下にて液体状態の流体と、常温で且つ常圧下にて気体状態の流体とを含む流体に圧力を加えることにより高圧流体とする場合には、例えば、常温で且つ常圧下にて液体状態の流体と、常温で且つ常圧下にて気体状態の流体とを含む流体中に黒鉛化合物を供給して混合体を作製し、この混合体の流体に、好ましくは混合体の流体を加熱しながら、圧力を加えて高圧流体とすると共に、黒鉛化合物を高圧流体に接触させる方法、常温で且つ常圧下にて液体状態の流体と、常温で且つ常圧下にて気体状態の流体とを含む流体を、好ましくは加熱しながら、加圧して高圧流体とした上で、この高圧流体内に黒鉛化合物を供給して黒鉛化合物を高圧流体に接触させる方法などが挙げられる。高圧流体を加熱する場合、高圧流体を20〜600℃に加熱することが好ましく、30〜400℃に加熱することがより好ましく、臨界点における温度(臨界温度Tc)以上の温度に高圧流体を加熱することが特に好ましい。高圧流体の加熱温度を上記範囲内とすることにより高圧流体を黒鉛化合物の層面間に十分に進入させることができる。   When applying a pressure to a fluid containing a fluid in a liquid state at normal temperature and normal pressure and a fluid in a gaseous state at normal temperature and normal pressure, for example, at normal temperature and normal pressure A graphite compound is supplied into a fluid containing a fluid in a liquid state and a fluid in a gas state at normal temperature and normal pressure to produce a mixture, and the fluid of the mixture is preferably added to the fluid of the mixture. While heating, a pressure is applied to form a high-pressure fluid, and a method in which a graphite compound is brought into contact with the high-pressure fluid. A fluid in a liquid state at normal temperature and normal pressure, and a fluid in a gaseous state at normal temperature and normal pressure. A method may be mentioned in which the fluid containing is pressurized, preferably while heating, to obtain a high-pressure fluid, a graphite compound is supplied into the high-pressure fluid, and the graphite compound is brought into contact with the high-pressure fluid. When heating the high-pressure fluid, the high-pressure fluid is preferably heated to 20 to 600 ° C., more preferably 30 to 400 ° C., and the high-pressure fluid is heated to a temperature equal to or higher than the temperature at the critical point (critical temperature Tc). It is particularly preferable to do this. By setting the heating temperature of the high pressure fluid within the above range, the high pressure fluid can sufficiently enter between the layer surfaces of the graphite compound.

高圧流体は常温で且つ常圧下にて気体状態の流体を含んでいるのが好ましい。常温で且つ常圧下にて気体状態の流体を含んでいる高圧流体は、これに加わる圧力を開放した時に気化することにより体積が特に大きくなることから、黒鉛化合物の層面同士を剥離する力に優れ、層面の積層数がより少なく高度に薄片化された薄片化黒鉛化合物を得ることができる。   The high-pressure fluid preferably contains a fluid in a gaseous state at normal temperature and normal pressure. A high-pressure fluid containing a fluid in a gaseous state at normal temperature and normal pressure has a particularly large volume when it is vaporized when the pressure applied to it is released. It is possible to obtain a exfoliated graphite compound having a smaller number of layer surfaces and highly exfoliated.

上述のようにして、黒鉛化合物を高圧流体に接触させる際に、黒鉛化合物若しくは混合体に超音波を照射し、又は、混合体をビーズミルを用いて攪拌してもよい。又、黒鉛化合物を高圧流体に接触させるにあたっては、汎用の装置を用いればよく、ヒーターを備えた密閉可能な耐圧容器を備えた装置、具体的には、オートクレーブなどを用いればよい。   As described above, when the graphite compound is brought into contact with the high-pressure fluid, the graphite compound or the mixture may be irradiated with ultrasonic waves, or the mixture may be stirred using a bead mill. In order to bring the graphite compound into contact with the high-pressure fluid, a general-purpose apparatus may be used, and an apparatus having a hermetic pressure-resistant container equipped with a heater, specifically, an autoclave may be used.

黒鉛化合物を高圧流体に接触させた後は、高圧流体に加わっている圧力を減圧するが、減圧後の流体に加わっている圧力が高過ぎると黒鉛化合物を十分に薄片化ができない虞れがあることから、高圧流体に加わっている圧力の減圧は、減圧後の流体に加わっている圧力が、好ましくは110kPa以下、より好ましくは105kPa以下となるまで行うのが好ましい。   After the graphite compound is brought into contact with the high-pressure fluid, the pressure applied to the high-pressure fluid is reduced. However, if the pressure applied to the fluid after the pressure reduction is too high, the graphite compound may not be sufficiently thinned. Therefore, it is preferable to reduce the pressure applied to the high-pressure fluid until the pressure applied to the fluid after the pressure reduction is preferably 110 kPa or less, more preferably 105 kPa or less.

また、高圧流体に加わっている圧力は急速に減圧するのが好ましい。高圧流体に加わっている圧力の減圧速度は、50MPa/秒以上が好ましく、500〜10,000MPa/秒がより好ましい。黒鉛化合物を高圧流体に接触させて高圧流体を黒鉛化合物の層面間に進入させた後に、高圧流体に加わっている圧力を急速に開放することで、黒鉛化合物の層面間に進入している高圧流体による黒鉛化合物の層面同士の剥離力を向上させることができる。   Further, it is preferable that the pressure applied to the high-pressure fluid is rapidly reduced. The pressure reduction rate of the pressure applied to the high-pressure fluid is preferably 50 MPa / second or more, and more preferably 500 to 10,000 MPa / second. After the graphite compound is brought into contact with the high-pressure fluid and the high-pressure fluid enters between the layer surfaces of the graphite compound, the pressure applied to the high-pressure fluid is rapidly released, so that the high-pressure fluid entering between the layer surfaces of the graphite compound The peeling force between the layer surfaces of the graphite compound due to can be improved.

上述のようにして、黒鉛化合物を薄片化して得られた薄片化黒鉛化合物を流体から分離する方法は特に限定されない。流体が常温で且つ常圧下にて液体状態の流体である場合には、例えば、流体を常温で且つ常圧とした上で、遠心分離などによって薄片化黒鉛化合物を流体から分離すればよい。流体が常温で且つ常圧下にて気体状態の流体である場合には、例えば、流体を常温で且つ常圧とした上で、流体中から薄片化黒鉛化合物を取り出せばよい。   The method for separating the exfoliated graphite compound obtained by exfoliating the graphite compound as described above from the fluid is not particularly limited. When the fluid is a fluid in a liquid state at normal temperature and normal pressure, for example, the exfoliated graphite compound may be separated from the fluid by centrifugation or the like after the fluid is at normal temperature and normal pressure. When the fluid is a fluid in a gaseous state at normal temperature and normal pressure, for example, the exfoliated graphite compound may be taken out from the fluid after the fluid is at normal temperature and normal pressure.

図1に、本発明の薄片化黒鉛化合物の製造方法に用いられる製造装置の一例を示す。図1において、1は金属塩溶融浴槽であり、その内部には金属塩2が貯留されている。また、金属塩溶融浴槽1内部には、金属塩の温度を測定するための熱電対3が配設されていると共に、金属塩2を加熱、溶融させるためのヒーター4が配設されており、熱電対3によってヒーター4がオン、オフされ、金属塩2の温度が所望温度に維持されるように構成されている。   In FIG. 1, an example of the manufacturing apparatus used for the manufacturing method of the exfoliated graphite compound of this invention is shown. In FIG. 1, 1 is a metal salt melting bath, in which a metal salt 2 is stored. In addition, a thermocouple 3 for measuring the temperature of the metal salt is disposed inside the metal salt melting bath 1, and a heater 4 for heating and melting the metal salt 2 is disposed, The heater 4 is turned on and off by the thermocouple 3, and the temperature of the metal salt 2 is maintained at a desired temperature.

5は黒鉛化合物と流体とを投入する製造容器であり、6は製造容器5内で製造された薄片化黒鉛化合物を回収するための回収容器である。製造容器5と回収容器6とは連結管7を介して連結、連通された状態となっている。具体的には、製造容器5には連結管7の一端部が連結、連通されていると共に、連結管7の他端部は回収容器6内に連結、連通されており、製造容器5内と回収容器6内とは連結管7を介して連結、連通されている。   Reference numeral 5 denotes a production container for charging the graphite compound and the fluid, and reference numeral 6 denotes a collection container for collecting the exfoliated graphite compound produced in the production container 5. The production container 5 and the collection container 6 are connected and communicated with each other via a connection pipe 7. Specifically, one end of the connecting pipe 7 is connected to and communicated with the manufacturing container 5, and the other end of the connecting pipe 7 is connected and communicated with the inside of the collection container 6. The inside of the collection container 6 is connected and communicated via a connecting pipe 7.

又、連結管7には三方弁7aを介して流体供給管71の一端部が連結、連通されていると共に、流体供給管71の他端部には、流体を貯蔵している流体ボンベ(図示せず)が連結されており、流体ボンベと製造容器5とは連結管7及び流体供給管71とを介して連結、連通した状態となっており、流体ボンベ内の流体はポンプ(図示せず)によって製造容器5内に圧入されるように構成されている。   In addition, one end of a fluid supply pipe 71 is connected to and communicated with the connection pipe 7 via a three-way valve 7a, and the other end of the fluid supply pipe 71 stores a fluid cylinder (see FIG. (Not shown) are connected, and the fluid cylinder and the production container 5 are connected and communicated with each other via the connecting pipe 7 and the fluid supply pipe 71, and the fluid in the fluid cylinder is pumped (not shown). ) To be press-fitted into the manufacturing container 5.

更に、9は真空ポンプであり、回収容器6と真空ポンプ9とは接続管10を介して連結、連通された状態となっている。具体的には、回収容器6には接続管10の一端部が連結、連通されていると共に、真空ポンプ9には接続管10の他端部が連結、連通されていることによって、回収容器6内と真空ポンプ9とが接続管10を介して連結、連通した状態となっている。そして、接続管10には開閉自在な開閉弁11が介在されており、この開閉弁11を開放することによって回収容器6内と真空ポンプ9内とが連結、連通した状態となる一方、開閉弁11を閉止させることによって回収容器6内と真空ポンプ9内とが遮断されるように構成されている。   Furthermore, 9 is a vacuum pump, and the recovery container 6 and the vacuum pump 9 are connected and communicated with each other via a connecting pipe 10. Specifically, one end of the connection pipe 10 is connected to and communicated with the recovery container 6, and the other end of the connection pipe 10 is connected to and communicated with the vacuum pump 9. The inside and the vacuum pump 9 are connected and communicated with each other via a connecting pipe 10. The connecting pipe 10 is provided with an openable / closable open / close valve 11. By opening the open / close valve 11, the inside of the collection container 6 and the vacuum pump 9 are connected and communicated with each other. By closing 11, the inside of the collection container 6 and the inside of the vacuum pump 9 are shut off.

上記では、加熱手段として金属塩溶融浴を用いたが、その他にも、例えば、電気ヒーター、バーナー、燃焼ガス、蒸気、熱媒、サンドバス等の加熱手段を用いてもよい。   In the above, the metal salt molten bath is used as the heating means, but other heating means such as an electric heater, a burner, a combustion gas, steam, a heating medium, and a sand bath may be used.

製造容器5は、製造容器5がその内部に充填した流体を高圧流体、特に亜臨界流体又は超臨界流体とするための圧力及び温度に耐えられるものであればよい。製造容器5を構成している材料としては、例えば、炭素鋼、Ni、Cr、V、Mo等の特殊鋼、オーステナイト系ステンレス鋼、ハステロイ(登録商標)、チタンなどの金属、又はこれらの金属にガラス、セラミック、カーバイト等をライニング処理したライニング材、上記金属のうち二種類の異なる金属を溶接などにより張り合わせたクラッド鋼が挙げられる。 The production container 5 only needs to be able to withstand the pressure and temperature for making the fluid filled in the production container 5 a high-pressure fluid, particularly a subcritical fluid or a supercritical fluid. Examples of the material constituting the production container 5 include carbon steel, special steels such as Ni, Cr, V, and Mo, austenitic stainless steel, Hastelloy (registered trademark) , metals such as titanium, and these metals. Examples thereof include a lining material obtained by lining glass, ceramic, carbide, etc., and clad steel obtained by bonding two different metals among the above metals by welding or the like.

製造容器5の形状は、特に制限されないが、耐熱性及び耐圧性を考慮すると、槽型又は管型であるのが好ましい。   The shape of the production container 5 is not particularly limited, but is preferably a tank type or a tube type in consideration of heat resistance and pressure resistance.

又、製造容器5内には、黒鉛化合物及び流体の他に、金属やセラミックなどからなる硬質ボールを投入しておくのが好ましい。黒鉛化合物と高圧流体とを接触させる際に製造容器5を振とうさせることによって硬質ボールを製造容器5内において不規則に変位させて高圧流体に乱流を生じさせることができ、高圧流体を黒鉛化合物に効率的に接触させて黒鉛化合物の層面間に進入し易くすることが可能となる。   In addition to the graphite compound and fluid, it is preferable to put hard balls made of metal, ceramic, or the like into the manufacturing container 5. By shaking the production vessel 5 when the graphite compound and the high-pressure fluid are brought into contact with each other, the hard balls can be irregularly displaced in the production vessel 5 to cause turbulence in the high-pressure fluid. It becomes possible to make it easy to enter between the layer surfaces of a graphite compound by contacting the compound efficiently.

次に、上記製造装置を用いて薄片化黒鉛化合物を製造する要領について説明する。先ず、製造容器5を開放して製造容器5内に黒鉛化合物及び流体を供給した後、製造容器5を閉止する。   Next, the point which manufactures exfoliated graphite compound using the said manufacturing apparatus is demonstrated. First, after the production container 5 is opened and the graphite compound and the fluid are supplied into the production container 5, the production container 5 is closed.

なお、製造容器5内に供給する流体の量及び製造容器5内の圧力は、後工程で製造容器5を所定の温度に加熱した時に、製造容器5内の流体が高圧流体、特に亜臨界流体又は超臨界流体となるように予め調整する。   The amount of fluid supplied to the production container 5 and the pressure in the production container 5 are such that when the production container 5 is heated to a predetermined temperature in a subsequent process, the fluid in the production container 5 is a high-pressure fluid, particularly a subcritical fluid. Or it adjusts beforehand so that it may become a supercritical fluid.

ここで、製造容器5内に常温で且つ常圧下にて気体状態の流体を供給する場合には、三方弁7aを操作して製造容器5内と流体ボンベ(図示せず)とを連結、連通させた状態とすると共に、製造容器5及び流体ボンベと、回収容器6内とは遮断された状態とする。そして、ポンプを駆動させて流体ボンベ内に充填されている流体を流体供給管71及び連結管7を通じて製造容器5内に供給して、三方弁7aと製造容器5との間の連結管7部分、及び、製造容器5内の空気を流体によって完全に置換した後、三方弁7aを操作して、製造容器5内と流体ボンベと回収容器6とが互いに遮断された状態とする。   Here, when supplying a fluid in a gaseous state at normal temperature and normal pressure into the production container 5, the three-way valve 7a is operated to connect and communicate between the production container 5 and a fluid cylinder (not shown). In addition, the manufacturing container 5 and the fluid cylinder are disconnected from the collection container 6. Then, by driving the pump, the fluid filled in the fluid cylinder is supplied into the production container 5 through the fluid supply pipe 71 and the connection pipe 7, and the connection pipe 7 portion between the three-way valve 7 a and the production container 5 is supplied. After the air in the production container 5 is completely replaced by the fluid, the three-way valve 7a is operated so that the production container 5, the fluid cylinder, and the recovery container 6 are blocked from each other.

又、流体が常温で且つ常圧下にて液体状態である場合には、製造容器5内に直接、流体を供給する。しかる後、三方弁7aを操作して製造容器5内と流体ボンベ(図示せず)とを連結、連通させた状態とすると共に、製造容器5及び流体ボンベと、回収容器6内とは遮断された状態とする。   Further, when the fluid is in a liquid state at normal temperature and under normal pressure, the fluid is supplied directly into the manufacturing container 5. Thereafter, the three-way valve 7a is operated to connect and communicate with the inside of the production container 5 and a fluid cylinder (not shown), and the production container 5, the fluid cylinder, and the inside of the collection container 6 are shut off. State.

更に、流体ボンベに代えて、窒素、アルゴンなどの不活性ガスを充填した不活性ガスボンベ(図示せず)を流体供給管71の他端部に接続し、不活性ガスボンベ内に充填されている不活性ガスを流体供給管71及び連結管7を通じて製造容器5内に供給して、三方弁7aと製造容器5との間の連結管7部分、及び、製造容器5内の空気を不活性ガスによって完全に置換した後、三方弁7aを操作して、製造容器5内と不活性ガスボンベと回収容器6とが互いに遮断された状態とすればよい。   Further, instead of the fluid cylinder, an inert gas cylinder (not shown) filled with an inert gas such as nitrogen or argon is connected to the other end of the fluid supply pipe 71, and the inert gas cylinder filled with the inert gas cylinder. The active gas is supplied into the production container 5 through the fluid supply pipe 71 and the connection pipe 7, and the connection pipe 7 portion between the three-way valve 7a and the production container 5 and the air in the production container 5 are inert gas. After complete replacement, the three-way valve 7a is operated so that the inside of the production vessel 5, the inert gas cylinder, and the recovery vessel 6 are blocked from each other.

更に、流体として、常温で且つ常圧下にて液体状態である流体と、常温で且つ常圧下にて気体状態である流体とを併用する場合には、製造容器5内に黒鉛化合物と共に直接、常温で且つ常圧下にて液体状態である流体を供給した後、上述と同様の要領にて常温で且つ常圧下にて気体状態である流体を製造容器5内に供給すればよい。   Further, when a fluid that is in a liquid state at normal temperature and normal pressure and a fluid that is in a gaseous state at normal temperature and normal pressure are used in combination as a fluid, In addition, after supplying the fluid in a liquid state under normal pressure, the fluid in a gaseous state at normal temperature and under normal pressure may be supplied into the production container 5 in the same manner as described above.

しかる後、製造容器5全体を金属塩溶融浴槽1の溶融状態の金属塩2中に投入し、製造容器5内の流体の温度を上昇させると共に製造容器5内の圧力を上昇させて、製造容器5内の流体を高圧流体、特に亜臨界流体又は超臨界流体とし、高圧流体(亜臨界流体又は超臨界流体)と黒鉛化合物とを所定時間に亘って接触させて、黒鉛化合物の層面間に高圧流体(亜臨界流体又は超臨界流体)を進入させる。製造容器5内で高圧流体と黒鉛化合物とを接触させている間は、黒鉛化合物の層面間に高圧流体(亜臨界流体又は超臨界流体)が進入していると共に、黒鉛化合物の周囲に存在している高圧流体(亜臨界流体又は超臨界流体)によって黒鉛化合物には圧力が加わっている。   Thereafter, the entire production container 5 is put into the molten metal salt 2 of the metal salt melting bath 1 to increase the temperature of the fluid in the production container 5 and the pressure in the production container 5 to increase the production container 5. 5 is a high-pressure fluid, particularly a subcritical fluid or a supercritical fluid, and the high-pressure fluid (subcritical fluid or supercritical fluid) and the graphite compound are brought into contact with each other for a predetermined time, and the high pressure is applied between the graphite compound layers. A fluid (subcritical fluid or supercritical fluid) is allowed to enter. While the high-pressure fluid and the graphite compound are in contact with each other in the production vessel 5, a high-pressure fluid (subcritical fluid or supercritical fluid) enters between the layer surfaces of the graphite compound and exists around the graphite compound. Pressure is applied to the graphite compound by the high pressure fluid (subcritical fluid or supercritical fluid).

一方、接続管10に介在させた開閉弁11を開放した上で真空ポンプを駆動させて回収容器6内を減圧状態とした後に、開閉弁11を閉止して真空ポンプを停止させる。なお、減圧状態とした後の回収容器6の内部圧力は0.1〜1,000kPaが好ましく、1〜100kPaがより好ましい。   On the other hand, after opening the on-off valve 11 interposed in the connecting pipe 10, the vacuum pump is driven to bring the collection container 6 into a decompressed state, and then the on-off valve 11 is closed to stop the vacuum pump. In addition, 0.1-1,000 kPa is preferable and, as for the internal pressure of the collection container 6 after making it a pressure reduction state, 1-100 kPa is more preferable.

次に、三方弁7aを操作して製造容器5と回収容器6とを連通させた状態とすると、製造容器5の内部圧力よりも回収容器6の内部圧力の方が低いため、製造容器5内の高圧流体は連結管7を通じて回収容器6内へ急速に移動し高圧流体に加わっている圧力が急速に減圧されると共に、上記高圧流体の移動に伴って製造容器5内の黒鉛化合物も連結管7を通じて回収容器6内へ流れる。このようにして高圧流体及び黒鉛化合物が回収容器6内へ流入する際、先ず、黒鉛化合物内に進入せずに黒鉛化合物の周囲に存在している高圧流体に加わっている圧力が急速に開放されることで黒鉛化合物に加わっている高圧流体による圧力も急速に開放される。一方、黒鉛化合物の層面間の隙間は極めて狭いことから、黒鉛化合物の周囲に存在している高圧流体に加わっている圧力が開放されても、その圧力の開放が黒鉛化合物の層面間の高圧流体に瞬時に伝達せず、その結果、黒鉛化合物の層面間に存在する高圧流体は、黒鉛化合物の周囲に存在する高圧流体に比して圧力が高くなった状態が発現する。この状態においては、黒鉛化合物の層面間に一旦、進入した高圧流体は、黒鉛化合物の層面間の隙間が狭いこともあって黒鉛化合物の層面間から容易に外部に出ることができず、黒鉛化合物の層面間において膨張し、この高圧流体の膨張によって黒鉛化合物の層面同士が剥離されて薄片化黒鉛化合物が得られる。特に、黒鉛化合物に接触させている高圧流体が亜臨界流体又は超臨界流体である場合、亜臨界流体又は超臨界流体は、黒鉛化合物の層面間に進入し易い一方、上述のように、高圧流体に加えられる圧力が開放されて減圧された状態においては、高圧流体はもはや亜臨界流体又は超臨界流体ではなく気体又は液体状態となっていることから、黒鉛化合物の層面間から外部に出ることが難しくなっており、黒鉛化合物の層面間に進入した高圧流体は黒鉛化合物の層面間において確実に膨張し、その結果、黒鉛化合物の層面同士をより高度に剥離させてなる薄片化黒鉛を得ることができる。しかる後、回収容器6を開放して回収容器6内から薄片化黒鉛化合物を取り出せばよい。   Next, when the three-way valve 7a is operated so that the production container 5 and the collection container 6 are in communication with each other, the internal pressure of the collection container 6 is lower than the internal pressure of the production container 5, so that the inside of the production container 5 The high-pressure fluid rapidly moves into the recovery container 6 through the connecting pipe 7 and the pressure applied to the high-pressure fluid is rapidly reduced, and the graphite compound in the production container 5 is also connected to the connecting pipe as the high-pressure fluid moves. 7 flows into the collection container 6. Thus, when the high-pressure fluid and the graphite compound flow into the recovery container 6, first, the pressure applied to the high-pressure fluid existing around the graphite compound without entering the graphite compound is rapidly released. As a result, the pressure due to the high-pressure fluid applied to the graphite compound is also rapidly released. On the other hand, the gap between the layer surfaces of the graphite compound is extremely narrow, so even if the pressure applied to the high-pressure fluid existing around the graphite compound is released, the release of the pressure is the high-pressure fluid between the layer surfaces of the graphite compound. As a result, the high-pressure fluid existing between the layer surfaces of the graphite compound develops a state in which the pressure is higher than that of the high-pressure fluid existing around the graphite compound. In this state, the high-pressure fluid once entered between the graphite compound layer surfaces cannot easily go out from between the graphite compound layer surfaces because the gap between the graphite compound layer surfaces is narrow. The graphite compound layer surfaces are separated from each other by the expansion of the high-pressure fluid, and a exfoliated graphite compound is obtained. In particular, when the high-pressure fluid in contact with the graphite compound is a subcritical fluid or a supercritical fluid, the subcritical fluid or supercritical fluid tends to enter between the layer surfaces of the graphite compound. In a state where the pressure applied to the pressure is released and the pressure is reduced, the high-pressure fluid is no longer a subcritical fluid or supercritical fluid but is in a gas or liquid state, so that it may exit from between the layer surfaces of the graphite compound. The high-pressure fluid that has entered between the layer surfaces of the graphite compound is reliably expanded between the layer surfaces of the graphite compound, and as a result, exfoliated graphite can be obtained by exfoliating the layer surfaces of the graphite compound more highly. it can. Thereafter, the collection container 6 is opened and the exfoliated graphite compound may be taken out from the collection container 6.

なお、常温で且つ常圧下にて気体状態の流体を用いた場合には、回収容器6内の容積及び圧力を予め調整しておき、回収容器6内に流体が流入した時点で流体が気化して気体状態となるようにして流体の回収を行ってもよいし、或いは、回収容器6内を開放して回収容器6内の圧力を常圧とし、回収容器6内の流体を気化させると共に流体の回収を行ってもよい。   When a fluid in a gaseous state at normal temperature and normal pressure is used, the volume and pressure in the collection container 6 are adjusted in advance, and the fluid is vaporized when the fluid flows into the collection container 6. The fluid may be recovered in a gaseous state, or the inside of the recovery container 6 is opened to make the pressure in the recovery container 6 normal, and the fluid in the recovery container 6 is vaporized and fluid May be recovered.

本発明の薄片化黒鉛化合物の製造方法は、上述のように、黒鉛化合物の酸化物を経ることなく黒鉛化合物を薄片化することが可能であるため、原料となる黒鉛化合物と同様の層面状態を有する薄片化黒鉛化合物を得ることができる。特に、薄片化黒鉛化合物を導電性材料に使用したい場合には、黒鉛化合物の薄片化後に薄片化黒鉛化合物の還元などの工程を経なくても炭素原子含有率が高く且つ導電性の高い薄片化黒鉛化合物を高効率で得ることができる。   As described above, the method for producing a exfoliated graphite compound of the present invention can exfoliate a graphite compound without passing through an oxide of the graphite compound. The exfoliated graphite compound can be obtained. In particular, if you want to use exfoliated graphite compounds as conductive materials, exfoliation with high carbon atom content and high conductivity is possible even after the exfoliation of the exfoliated graphite compound without steps such as reduction of exfoliated graphite compound. A graphite compound can be obtained with high efficiency.

得られた薄片化黒鉛化合物において、元素分析方法によって得られたC/O比は、50以上が好ましく、100以上がより好ましく、500以上が特に好ましい。そして、薄片化黒鉛化合物において、元素分析方法によって得られたC/O比はCHNO元素分析によって測定することができる。   In the exfoliated graphite compound obtained, the C / O ratio obtained by the elemental analysis method is preferably 50 or more, more preferably 100 or more, and particularly preferably 500 or more. In the exfoliated graphite compound, the C / O ratio obtained by the elemental analysis method can be measured by CHNO elemental analysis.

薄片化黒鉛化合物の炭素元素量は、60原子%以上が好ましく、80原子%以上がより好ましい。薄片化黒鉛化合物の炭素元素量が60原子%未満である薄片化黒鉛化合物は、これを構成している炭素−炭素SP2混成軌道が減少し且つ他の原子の存在によって薄片化黒鉛化合物の平滑性が損なわれ、或いは、薄片化黒鉛化合物を構成している炭素−炭素SP2混成軌道の共役性が損なわれて導電性が低下することがあるからである。 The amount of carbon element in the exfoliated graphite compound is preferably 60 atomic percent or more, and more preferably 80 atomic percent or more. The exfoliated graphite compound in which the amount of carbon element in the exfoliated graphite compound is less than 60 atomic% is reduced in the carbon-carbon SP 2 hybrid orbital constituting the exfoliated graphite compound and the smoothness of the exfoliated graphite compound by the presence of other atoms This is because the conductivity may be impaired, or the conductivity of the carbon-carbon SP 2 hybrid orbital constituting the exfoliated graphite compound may be impaired to lower the conductivity.

又、得られた薄片化黒鉛化合物において、層面の積層数は、20層以下が好ましく、10層以下がより好ましく、5層以下が特に好ましい。なお、薄片化黒鉛化合物における層面の積層数は、電子顕微鏡を用いて薄片化黒鉛化合物を観察することによって測定することができる。   Moreover, in the obtained exfoliated graphite compound, the number of laminated layers is preferably 20 layers or less, more preferably 10 layers or less, and particularly preferably 5 layers or less. The number of laminated layer surfaces in the exfoliated graphite compound can be measured by observing the exfoliated graphite compound using an electron microscope.

得られた薄片化黒鉛化合物における層面の面方向に沿った大きさは、小さいと、後述するように、薄片化黒鉛化合物と合成樹脂とを混合して複合体とした場合、複合体において、剛性、バリア性、低い熱膨張性(寸法安定性)などの所望の性能が発現しにくいことがあり、大きいと、複合体の表面に薄片化黒鉛化合物が露出して複合体の外観が低下することがあるので、5〜200μmが好ましい。なお、得られた薄片化黒鉛化合物における層面の面方向に沿った大きさは、SEMやTEMによって観察された値をいう。   When the size of the exfoliated graphite compound along the surface direction of the layer surface is small, as described later, when the exfoliated graphite compound and the synthetic resin are mixed to form a composite, the composite has rigidity. Desirable performance such as barrier properties and low thermal expansion (dimensional stability) may be difficult to express, and if large, exfoliated graphite compound is exposed on the surface of the composite and the appearance of the composite is degraded. Therefore, 5 to 200 μm is preferable. In addition, the magnitude | size along the surface direction of the layer surface in the obtained exfoliated graphite compound means the value observed by SEM and TEM.

又、得られた薄片化黒鉛化合物において、層面の面方向に沿った大きさと厚さとの比(層面の面方向に沿った大きさ/厚さ)は、小さいと、後述するように複合体として用いた場合に薄片化黒鉛化合物の性能を充分に発揮させることができないことがあるので、100以上が好ましく、100〜10000がより好ましい。   Further, in the obtained exfoliated graphite compound, if the ratio of the size and the thickness along the surface direction of the layer surface (size / thickness along the surface direction of the layer surface) is small, a composite as will be described later. When used, the performance of the exfoliated graphite compound may not be sufficiently exhibited, so 100 or more is preferable, and 100 to 10,000 is more preferable.

更に、薄片化黒鉛化合物は、薄片化する前の黒鉛化合物よりも高い比表面積を有する。具体的には、薄片化黒鉛化合物のBET比表面積は、100m2/g以上が好ましく、200〜2600m2/gがより好ましい。なお、BET比表面積とは、窒素ガスを用いたBET法により測定した物質1g当たりの表面積を意味する。 Furthermore, the exfoliated graphite compound has a higher specific surface area than the graphite compound before exfoliation. Specifically, BET specific surface area of exfoliated graphite compound is preferably at least 100m 2 / g, 200~2600m 2 / g is more preferable. In addition, a BET specific surface area means the surface area per 1g of substance measured by BET method using nitrogen gas.

得られた薄片化黒鉛化合物は合成樹脂と混合することによって複合体として用いることができ、複合体は、バリア性材料、耐熱性材料、耐候性材料、電気伝導性材料、熱伝導性材料、IR反射性材料、寸法安定性に優れた低膨張性材料などとして用いることができる。   The obtained exfoliated graphite compound can be used as a composite by mixing with a synthetic resin, and the composite is a barrier material, heat-resistant material, weather-resistant material, electrically conductive material, thermally conductive material, IR It can be used as a reflective material, a low expansion material excellent in dimensional stability, and the like.

合成樹脂としては、例えば、アクリル系樹脂、メタクリル系樹脂、ポリエチレン系樹脂、ポリプロピレン系樹脂、ポリエステル系樹脂、ポリアミド樹脂、スチレン−アクリロニトリル共重合体などのポリスチレン系樹脂、ポリカーボネート系樹脂、ポリカプロラクトン、ポリカプロラクタム、ポリフッ素化エチレン、ポリ酢酸ビニル樹脂、ポリ塩化ビニル系樹脂、ポリイミド系樹脂、エポキシ系樹脂、ポリウレタン系樹脂、ポリブタジエン、ブチルゴム、スチレン−ブタジエン共重合体、ポリイソプレン、ポリジメチルシロキサンなどが挙げられる。なお、合成樹脂は単独で用いられても二種以上が併用されてもよい。又、モノマーとしては、上述の合成樹脂を構成しているモノマーが挙げられ、例えば、アクリル酸、アクリル酸メチル、メタクリル酸、メタクリル酸メチル、エチレン、プロピレン、スチレン、α−メチルスチレン、アクリロニトリル、酢酸ビニル、塩化ビニル、ブタジエン、イソプレンなどが挙げられる。   Synthetic resins include, for example, acrylic resins, methacrylic resins, polyethylene resins, polypropylene resins, polyester resins, polyamide resins, polystyrene resins such as styrene-acrylonitrile copolymers, polycarbonate resins, polycaprolactone, poly Caprolactam, polyfluorinated ethylene, polyvinyl acetate resin, polyvinyl chloride resin, polyimide resin, epoxy resin, polyurethane resin, polybutadiene, butyl rubber, styrene-butadiene copolymer, polyisoprene, polydimethylsiloxane, etc. It is done. In addition, a synthetic resin may be used independently or 2 or more types may be used together. In addition, examples of the monomer include monomers constituting the above-described synthetic resin. For example, acrylic acid, methyl acrylate, methacrylic acid, methyl methacrylate, ethylene, propylene, styrene, α-methylstyrene, acrylonitrile, acetic acid. Examples include vinyl, vinyl chloride, butadiene, and isoprene.

黒鉛層間化合物を形成するために用いたインターカレーターが酸化剤又は酸である場合、黒鉛層間化合物の各層面は酸化物を形成している。この黒鉛層間化合物を上述の要領で薄片化して得られた薄片化黒鉛化合物はその各層面が酸化しており、各層面は酸化グラフェンと呼ばれる。   When the intercalator used for forming the graphite intercalation compound is an oxidizing agent or an acid, each layer surface of the graphite intercalation compound forms an oxide. The exfoliated graphite compound obtained by exfoliating this graphite intercalation compound in the above-described manner has each layer surface oxidized, and each layer surface is called graphene oxide.

この酸化グラフェンからなる薄片化黒鉛化合物を導電膜などの用途に用いる場合には、高い導電性を得るために、酸化グラフェンを還元することが好ましい。薄片化黒鉛化合物を構成している酸化グラフェンの還元方法としては、特に限定されず、例えば、薄片化黒鉛化合物を構成している酸化グラフェンに還元剤を接触させる方法が挙げられる。   When the exfoliated graphite compound made of graphene oxide is used for a conductive film or the like, it is preferable to reduce the graphene oxide in order to obtain high conductivity. The method for reducing graphene oxide constituting the exfoliated graphite compound is not particularly limited, and examples thereof include a method of bringing a reducing agent into contact with graphene oxide constituting the exfoliated graphite compound.

本発明は、上述のように、黒鉛化合物を高圧流体に接触させて上記黒鉛化合物を薄片化することを特徴とするので、黒鉛化合物の層面同士を円滑に剥離して薄片化黒鉛化合物を効率良く製造することができる。   As described above, the present invention is characterized in that the graphite compound is brought into contact with a high-pressure fluid so as to exfoliate the graphite compound. Therefore, the layer surfaces of the graphite compound are smoothly separated to efficiently exfoliate the exfoliated graphite compound. Can be manufactured.

本発明の方法に好適に用いられる薄片化黒鉛化合物の製造装置を示した模式図である。It is the schematic diagram which showed the manufacturing apparatus of the exfoliated graphite compound used suitably for the method of this invention.

以下に、本発明を実施例を用いてより具体的に説明するが、本発明はこれに限定されない。   Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(比較例1)
図1に示した製造装置を用いて、以下の要領に従って薄片化黒鉛化合物を製造した。先ず、管型の製造容器5(SUS316ステンレス鋼、松菱鋼機株式会社製 Tube Bomb Reacter、内容積0.01リットル)を開放して、製造容器5内に黒鉛シート(東洋炭素社製 PF100−UHP)0.5gを投入した上で製造容器5を閉止した。
(Comparative Example 1)
Using the production apparatus shown in FIG. 1, exfoliated graphite compound was produced according to the following procedure. First, the tubular production container 5 (SUS316 stainless steel, Tube Bomb Reactor manufactured by Shohishi Steel Machine Co., Ltd., inner volume 0.01 liter) is opened, and a graphite sheet (PF100-UHP manufactured by Toyo Tanso Co., Ltd.) is placed in the production container 5. ) 0.5 g was charged and the production container 5 was closed.

次に、三方弁7aを操作して製造容器5と流体ボンベ(図示せず)とを連通させた状態とすると共に、製造容器5及び流体ボンベと、回収容器6内とが遮断された状態とした。そして、ポンプを駆動させて流体ボンベ内に充填されている常温で且つ常圧下にて気体状態である二酸化炭素4.8gを流体供給管71及び連結管7を通じて製造容器5内に供給した後、三方弁7aを操作して製造容器5内と流体ボンベと回収容器6とが互いに遮断された状態とした。なお、三方弁7aと製造容器5との間の連結管7部分、及び、製造容器5内は完全に二酸化炭素で置換されていた。   Next, the three-way valve 7a is operated to make the production container 5 and a fluid cylinder (not shown) communicate with each other, and the production container 5, the fluid cylinder, and the inside of the collection container 6 are shut off. did. Then, after driving the pump and supplying 4.8 g of carbon dioxide in a gaseous state at normal temperature and normal pressure filled in the fluid cylinder into the production container 5 through the fluid supply pipe 71 and the connecting pipe 7, The three-way valve 7a was operated so that the inside of the production container 5, the fluid cylinder, and the recovery container 6 were shut off from each other. The connecting pipe 7 portion between the three-way valve 7a and the production container 5 and the inside of the production container 5 were completely replaced with carbon dioxide.

一方、接続管10に介在させた開閉弁11を開放した上で真空ポンプを駆動させて回収容器6内部の空気を真空ポンプ9によって外部へ排出し、回収容器6内の圧力が10kPaとなるまで減圧した後に、開閉弁11を閉止して真空ポンプを停止させた。   On the other hand, after opening the on-off valve 11 interposed in the connecting pipe 10, the vacuum pump is driven to discharge the air in the collection container 6 to the outside by the vacuum pump 9, until the pressure in the collection container 6 reaches 10 kPa. After decompression, the on-off valve 11 was closed to stop the vacuum pump.

しかる後、製造容器5全体を金属塩溶融浴槽1の溶融状態の金属塩2中に投入し、製造容器5内の流体の温度を90℃まで上昇させると共に製造容器5内の圧力を18MPaまで上昇させて、二酸化炭素の超臨界流体を得ると共に、超臨界流体と黒鉛シートを1.5時間に亘って接触させ、黒鉛シートの層面間に二酸化炭素の超臨界流体を進入させた。   Thereafter, the entire production container 5 is put into the molten metal salt 2 of the metal salt melting bath 1, the temperature of the fluid in the production container 5 is increased to 90 ° C., and the pressure in the production container 5 is increased to 18 MPa. Thus, a supercritical fluid of carbon dioxide was obtained, and the supercritical fluid and the graphite sheet were brought into contact with each other for 1.5 hours, so that the supercritical fluid of carbon dioxide entered between the layer surfaces of the graphite sheet.

そして、三方弁7aを操作して、製造容器5と回収容器6内とを連通させた状態とし、製造容器5内の二酸化炭素の超臨界流体を連結管7を通じて回収容器6内に移動させると共に、二酸化炭素の超臨界流体に加わっていた圧力を1,000MPa/秒の減圧速度で0.1MPaまで減圧した。また、二酸化炭素の超臨界流体は減圧に伴って気化して気体状態となった。上記二酸化炭素の超臨界流体の移動及び減圧に伴って、黒鉛シートもまた製造容器5内から回収容器6内に移動すると共に薄片化されて薄片化黒鉛化合物を得た。その後、回収容器内を開放して常圧とした後に回収容器6内部をエタノールで洗浄することによって、回収容器6の内部に残っている薄片化黒鉛化合物を更に回収した。   Then, the three-way valve 7a is operated to make the production container 5 and the collection container 6 communicate with each other, and the supercritical fluid of carbon dioxide in the production container 5 is moved into the collection container 6 through the connecting pipe 7. The pressure applied to the supercritical fluid of carbon dioxide was reduced to 0.1 MPa at a pressure reduction rate of 1,000 MPa / second. In addition, the supercritical fluid of carbon dioxide was vaporized as the pressure decreased, and became a gaseous state. As the carbon dioxide supercritical fluid moved and depressurized, the graphite sheet also moved from the production vessel 5 into the collection vessel 6 and was exfoliated to obtain an exfoliated graphite compound. Thereafter, the inside of the collection container 6 was opened to normal pressure, and the inside of the collection container 6 was washed with ethanol, whereby the exfoliated graphite compound remaining in the collection container 6 was further collected.

(実施例
図1に示した製造装置を用いて、以下の要領に従って薄片化黒鉛化合物を製造した。先ず、管型の製造容器5(SUS316ステンレス鋼、松菱鋼機株式会社製 Tube Bomb Reacter、内容積10cm3)を開放して、製造容器5内に黒鉛シート(東洋炭素社製 PF100−UHP)0.5gを投入した。
(Example 1 )
Using the production apparatus shown in FIG. 1, exfoliated graphite compound was produced according to the following procedure. First, the tubular production container 5 (SUS316 stainless steel, Tube Bomb Reactor manufactured by Shohishi Steel Machine Co., Ltd., internal volume 10 cm 3 ) is opened, and a graphite sheet (PF100-UHP manufactured by Toyo Tanso Co., Ltd.) 0 is placed in the production container 5. .5 g was charged.

更に、製造容器5内に、常温で且つ常圧下にて流体状態であるエタノール1.8gを直接、供給した後に製造容器5を閉止した。窒素ガスを充填した窒素ガスボンベ(図示せず)を流体供給管71の他端部に接続し、三方弁7aを操作して製造容器5と窒素ガスボンベとを連結、連通させた状態とすると共に、製造容器5及び窒素ガスボンベと、回収容器6内とは遮断された状態とした。そして、ポンプを駆動させて窒素ガスボンベ内に充填されている窒素ガスを流体供給管71及び連結管7を通じて製造容器5内に供給して、三方弁7aと製造容器5との間の連結管7部分、及び、製造容器5内の空気を窒素ガスによって完全に置換した後、三方弁7aを操作して、製造容器5内と窒素ガスボンベと回収容器6とが互いに遮断された状態とした。なお、ここで充填した窒素ガスは0.9mgと非常に微量であるので、後工程においてエタノールを加圧及び加熱することにより超臨界流体として黒鉛化合物を薄片化する際に窒素ガスが黒鉛化合物の薄片化に影響を及ぼすことはない。   Further, 1.8 g of ethanol in a fluid state at normal temperature and normal pressure was directly supplied into the production container 5 and then the production container 5 was closed. A nitrogen gas cylinder (not shown) filled with nitrogen gas is connected to the other end of the fluid supply pipe 71, and the three-way valve 7a is operated to connect and connect the production container 5 and the nitrogen gas cylinder. The production container 5 and the nitrogen gas cylinder were separated from the inside of the collection container 6. Then, the pump is driven to supply nitrogen gas filled in the nitrogen gas cylinder into the production container 5 through the fluid supply pipe 71 and the connection pipe 7, and the connection pipe 7 between the three-way valve 7 a and the production container 5. After the part and the air in the production container 5 were completely replaced with nitrogen gas, the three-way valve 7a was operated so that the production container 5, the nitrogen gas cylinder, and the recovery container 6 were isolated from each other. In addition, since nitrogen gas filled here is a very small amount of 0.9 mg, when the graphite compound is exfoliated as a supercritical fluid by pressurizing and heating ethanol in the subsequent process, Does not affect flaking.

一方、接続管10に介在させた開閉弁11を開放した上で真空ポンプを駆動させて回収容器6内部の空気を真空ポンプ9によって外部へ排出し、回収容器6内の圧力が10kPaとなるまで減圧した後に、開閉弁11を閉止して真空ポンプを停止させた。   On the other hand, after opening the on-off valve 11 interposed in the connecting pipe 10, the vacuum pump is driven to discharge the air in the collection container 6 to the outside by the vacuum pump 9, until the pressure in the collection container 6 reaches 10 kPa. After decompression, the on-off valve 11 was closed to stop the vacuum pump.

しかる後、製造容器5全体を金属塩溶融浴槽1の溶融状態の金属塩2中に投入し、製造容器5内のエタノールの温度を285℃まで上昇させると共に製造容器5内の圧力を13MPaまで上昇させて、エタノールの超臨界流体を得ると共に、超臨界流体と黒鉛シートを0.5時間に亘って接触させ、黒鉛シートの層面間にエタノールの超臨界流体を進入させた。   Thereafter, the entire production container 5 is put into the molten metal salt 2 of the metal salt melting bath 1, the temperature of ethanol in the production container 5 is increased to 285 ° C., and the pressure in the production container 5 is increased to 13 MPa. Thus, an ethanol supercritical fluid was obtained, and the supercritical fluid and the graphite sheet were brought into contact with each other for 0.5 hour, so that the ethanol supercritical fluid entered between the layer surfaces of the graphite sheet.

そして、三方弁7aを操作して、製造容器5と回収容器6内とを連通させた状態として、製造容器5内のエタノールの超臨界流体を連結管7を通じて回収容器6内に移動させると共に、エタノールの超臨界流体に加わっていた圧力を1,000MPa/秒の減圧速度で0.1MPaまで減圧した。上記エタノールの超臨界流体の移動及び減圧に伴って、黒鉛シートもまた製造容器5内から回収容器6内に移動すると共に薄片化されて薄片化黒鉛化合物を得た。その後、回収容器内を開放して常圧とした後に回収容器6内部をエタノールで洗浄することによって、回収容器6の内部に残っている薄片化黒鉛化合物を回収した。   Then, the three-way valve 7a is operated to make the production container 5 and the collection container 6 communicate with each other, and the ethanol supercritical fluid in the production container 5 is moved into the collection container 6 through the connecting pipe 7, The pressure applied to the supercritical fluid of ethanol was reduced to 0.1 MPa at a pressure reduction rate of 1,000 MPa / second. As the ethanol supercritical fluid moved and depressurized, the graphite sheet also moved from the production vessel 5 into the collection vessel 6 and was exfoliated to obtain an exfoliated graphite compound. Thereafter, the inside of the recovery container 6 was opened to normal pressure, and the interior of the recovery container 6 was washed with ethanol, whereby the exfoliated graphite compound remaining in the recovery container 6 was recovered.

(実施例
エタノールに代えて、メタノール1.8gを用いた以外は、実施例と同様にして薄片化黒鉛化合物を製造した。
(Example 2 )
A exfoliated graphite compound was produced in the same manner as in Example 1 except that 1.8 g of methanol was used instead of ethanol.

(実施例
図1に示した製造装置を用いて、以下の要領に従って薄片化黒鉛化合物を製造した。先ず、管型の製造容器5(SUS316ステンレス鋼、松菱鋼機株式会社製 Tube Bomb Reacter、内容積10cm3)を開放して、製造容器5内に黒鉛シート(東洋炭素社製 PF100−UHP)0.5gを投入した。
(Example 3 )
Using the production apparatus shown in FIG. 1, exfoliated graphite compound was produced according to the following procedure. First, the tubular production container 5 (SUS316 stainless steel, Tube Bomb Reactor manufactured by Shohishi Steel Machine Co., Ltd., internal volume 10 cm 3 ) is opened, and a graphite sheet (PF100-UHP manufactured by Toyo Tanso Co., Ltd.) 0 is placed in the production container 5. .5 g was charged.

次に、製造容器5内に、常温で且つ常圧下にて流体状態である水2.5gを直接、供給した後に製造容器5を閉止した。しかる後、三方弁7aを操作して製造容器5と流体ボンベ(図示せず)とを連通させた状態とすると共に、製造容器5及び流体ボンベと、回収容器6内とが遮断された状態とした。そして、ポンプを駆動させて流体ボンベ内に充填されている常温で且つ常圧下にて気体状態である二酸化炭素1.2gを流体供給管71及び連結管7を通じて製造容器5内に供給した後、三方弁7aを操作して製造容器5内と流体ボンベと回収容器6とが互いに遮断された状態とした。なお、三方弁7aと製造容器5との間の連結管7部分、及び、製造容器5内の空気は完全に二酸化炭素で置換されていた。   Next, 2.5 g of water in a fluid state was directly supplied into the production container 5 at normal temperature and normal pressure, and then the production container 5 was closed. Thereafter, the three-way valve 7a is operated so that the production container 5 and a fluid cylinder (not shown) are in communication with each other, and the production container 5, the fluid cylinder, and the inside of the recovery container 6 are blocked. did. Then, after driving the pump and supplying 1.2 g of carbon dioxide in a gaseous state at normal temperature and normal pressure filled in the fluid cylinder into the production container 5 through the fluid supply pipe 71 and the connecting pipe 7, The three-way valve 7a was operated so that the inside of the production container 5, the fluid cylinder, and the recovery container 6 were shut off from each other. In addition, the connection pipe 7 part between the three-way valve 7a and the production container 5 and the air in the production container 5 were completely replaced with carbon dioxide.

一方、接続管10に介在させた開閉弁11を開放した上で真空ポンプを駆動させて回収容器6内部の空気を真空ポンプ9によって外部へ排出し、回収容器6内の圧力が10kPaとなるまで減圧した後に、開閉弁11を閉止して真空ポンプを停止させた。   On the other hand, after opening the on-off valve 11 interposed in the connecting pipe 10, the vacuum pump is driven to discharge the air in the collection container 6 to the outside by the vacuum pump 9, until the pressure in the collection container 6 reaches 10 kPa. After decompression, the on-off valve 11 was closed to stop the vacuum pump.

しかる後、製造容器5全体を金属塩溶融浴槽1の溶融させた金属塩2中に投入し、製造容器5内の水及び二酸化炭素の温度を390℃まで上昇させると共に製造容器5内の圧力を38MPaまで上昇させて、水及び二酸化炭素の超臨界流体を得ると共に、超臨界流体と黒鉛シートを1.5時間に亘って接触させ、黒鉛シートの層面間に水及び二酸化炭素の超臨界流体を進入させた。   Thereafter, the entire production container 5 is put into the molten metal salt 2 of the metal salt melting bath 1, the temperature of water and carbon dioxide in the production container 5 is increased to 390 ° C., and the pressure in the production container 5 is increased. The pressure is raised to 38 MPa to obtain a supercritical fluid of water and carbon dioxide, and the supercritical fluid and the graphite sheet are brought into contact with each other for 1.5 hours. I entered.

そして、三方弁7aを操作して、製造容器5と回収容器6内とを連通させた状態とし、製造容器5内の二酸化炭素及び水の超臨界流体を連結管7を通じて回収容器6内に移動させると共に、水及び二酸化炭素の超臨界流体に加わっていた圧力を2,000MPa/秒の減圧速度で0.1MPaまで減圧した。また、二酸化炭素の超臨界流体は減圧に伴って気化して気体状態となった。上記水及び二酸化炭素の超臨界流体の移動及び減圧に伴って、黒鉛シートもまた製造容器5内から回収容器6内に移動すると共に薄片化されて薄片化黒鉛化合物を得た。その後、回収容器内を開放して常圧とした後に回収容器6内部をエタノールで洗浄することによって、回収容器6の内部に残っている薄片化黒鉛化合物を更に回収した。   Then, the three-way valve 7a is operated to make the production container 5 and the collection container 6 communicate with each other, and the carbon dioxide and water supercritical fluid in the production container 5 are moved into the collection container 6 through the connecting pipe 7. In addition, the pressure applied to the supercritical fluid of water and carbon dioxide was reduced to 0.1 MPa at a reduced pressure rate of 2,000 MPa / second. In addition, the supercritical fluid of carbon dioxide was vaporized as the pressure decreased, and became a gaseous state. Along with the movement and decompression of the supercritical fluid of water and carbon dioxide, the graphite sheet also moved from the production container 5 into the recovery container 6 and was exfoliated to obtain a exfoliated graphite compound. Thereafter, the inside of the collection container 6 was opened to normal pressure, and the inside of the collection container 6 was washed with ethanol, whereby the exfoliated graphite compound remaining in the collection container 6 was further collected.

(比較例2、実施例4〜6)
黒鉛シートに代えて、以下の要領に従って作製した黒鉛層間化合物0.5g用い、製造容器5に供給した流体の量をそれぞれ表1の通りに変更した以外は、比較例1、実施例1〜3と同様にして薄片化黒鉛化合物を製造した。
(Comparative example 2, Examples 4-6)
Comparative Example 1 and Examples 1 to 3 except that 0.5 g of a graphite intercalation compound prepared according to the following procedure was used in place of the graphite sheet, and the amount of fluid supplied to the production vessel 5 was changed as shown in Table 1. The exfoliated graphite compound was produced in the same manner as described above.

(黒鉛層間化合物の作製)
黒鉛単結晶粉末0.25gを65重量%濃硫酸11.5ミリリットルに供給して、得られた混合物を10℃の水浴により冷却しながら撹拌した。次に、黒鉛単結晶粉末と濃硫酸との撹拌によって得られた混合物に、過マンガン酸カリウム1.5gを徐々に加えながら混合物を撹拌し、混合物を35℃で30分に亘って反応させた。
(Preparation of graphite intercalation compound)
0.25 g of graphite single crystal powder was supplied to 11.5 ml of 65 wt% concentrated sulfuric acid, and the resulting mixture was stirred while being cooled by a 10 ° C. water bath. Next, the mixture was stirred while gradually adding 1.5 g of potassium permanganate to the mixture obtained by stirring the graphite single crystal powder and concentrated sulfuric acid, and the mixture was reacted at 35 ° C. for 30 minutes. .

次に、反応混合物に水23gを徐々に加えて、混合物を98℃で15分に亘って反応させた。しかる後、反応混合物に水70gと30重量%の過酸化水素水4.5gを加えて反応を停止させた。混合物を14000rpmの回転速度にて30分に亘って遠心分離した後、得られた酸化黒鉛を5重量%の希塩酸及び水により十分に洗浄して、しかる後に乾燥させることにより黒鉛層間化合物を得た。   Next, 23 g of water was gradually added to the reaction mixture, and the mixture was reacted at 98 ° C. for 15 minutes. Thereafter, 70 g of water and 4.5 g of 30% by weight hydrogen peroxide were added to the reaction mixture to stop the reaction. After centrifuging the mixture at a rotation speed of 14000 rpm for 30 minutes, the obtained graphite oxide was sufficiently washed with 5% by weight of diluted hydrochloric acid and water, and then dried to obtain a graphite intercalation compound. .

(比較例3)
比較例1において、三方弁7aを操作して、製造容器5と回収容器6内とを連通させた状態とし、製造容器5内の二酸化炭素の超臨界流体を連結管7を通じて回収容器6内に移動させる際に、三方弁7aを操作して、製造容器5内の二酸化炭素の超臨界流体を連結管7を通じて回収容器6内に移動させると共に、二酸化炭素の超臨界流体に加わっていた圧力を70MPa/秒の減圧速度で0.1MPaまで減圧した以外は、比較例1と同様にして薄片化黒鉛化合物を製造した。
(Comparative Example 3)
In Comparative Example 1 , the three-way valve 7a is operated to make the production container 5 and the collection container 6 communicate with each other, and the supercritical fluid of carbon dioxide in the production container 5 enters the collection container 6 through the connecting pipe 7. When moving, the three-way valve 7a is operated to move the supercritical fluid of carbon dioxide in the production container 5 into the recovery container 6 through the connecting pipe 7, and the pressure applied to the supercritical fluid of carbon dioxide is changed. Exfoliated graphite compound was produced in the same manner as Comparative Example 1 except that the pressure was reduced to 0.1 MPa at a pressure reduction rate of 70 MPa / second.

(評価)
上記で作製した薄片化黒鉛化合物について、回収率、比表面積、及び炭素元素量を以下の手順に従って評価し、これらの結果を表1に示す。又、各実施例において原料として用いた黒鉛シート及び黒鉛層間化合物についても、比表面積、及び炭素元素量を以下の手順に従って評価し、これらの結果を参考例1及び参考例2として表1に示す。なお、表1において、エタノールは「EtOH」とし、メタノールは「MeOH」として記載した。
(Evaluation)
About the exfoliated graphite compound produced above, a recovery rate, a specific surface area, and the amount of carbon elements were evaluated according to the following procedures, and these results are shown in Table 1. Further, the graphite sheet and graphite intercalation compound used as raw materials in each Example were also evaluated for specific surface area and carbon element amount according to the following procedures, and these results are shown in Table 1 as Reference Example 1 and Reference Example 2. . In Table 1, ethanol is described as “EtOH” and methanol is described as “MeOH”.

(回収率)
原料として用いた黒鉛シート又は黒鉛層間化合物の重量W1と、薄片化黒鉛化合物の重量W2とを測定した後、得られた値から式:回収率(%)=W2/W1により、薄片化黒鉛化合物の回収率を算出した。
(Recovery rate)
After measuring the weight W 1 of the graphite sheet or graphite intercalation compound used as the raw material and the weight W 2 of the exfoliated graphite compound, from the values obtained, the formula: recovery rate (%) = W 2 / W 1 The recovery rate of the exfoliated graphite compound was calculated.

(比表面積)
薄片化黒鉛化合物、黒鉛シート又は黒鉛層間化合物のBET比表面積(m2/g)を、比表面積測定装置(島津製作所(株)製 ASAP−2000)を使用し、吸着ガスとして窒素ガスを用いたBET法により測定した。
(Specific surface area)
The BET specific surface area (m 2 / g) of exfoliated graphite compound, graphite sheet or graphite intercalation compound was measured using a specific surface area measuring device (ASAP-2000, manufactured by Shimadzu Corporation), and nitrogen gas was used as the adsorption gas. It was measured by the BET method.

(炭素元素量)
薄片化黒鉛化合物、黒鉛シート又は黒鉛層間化合物の炭素元素量(原子%)を、質量分析計(ION−TOF社製 TOF−SIMS Type−5)を用いて測定した。
(Amount of carbon element)
The carbon element amount (atomic%) of the exfoliated graphite compound, graphite sheet, or graphite intercalation compound was measured using a mass spectrometer (TOF-SIMS Type-5 manufactured by ION-TOF).

Figure 0005391216
Figure 0005391216

1 金属塩溶融浴槽
2 金属塩
3 熱電対
4 ヒーター
5 製造容器
6 回収容器
7a 三方弁
7 連結管
9 真空ポンプ
10 接続管
11 開閉弁
71 流体供給管
1 Metal Salt Melting Bath 2 Metal Salt 3 Thermocouple 4 Heater 5 Manufacturing Container 6 Recovery Container
7a Three-way valve 7 Connecting pipe 9 Vacuum pump
10 Connection pipe
11 On-off valve
71 Fluid supply pipe

Claims (4)

黒鉛化合物を常温で且つ常圧下にて液体状態の流体を含む流体の亜臨界流体又は超臨界流体に接触させた後、上記亜臨界流体又は上記超臨界流体に加わっている圧力を減圧することにより、上記黒鉛化合物を薄片化することを特徴とする薄片化黒鉛化合物の製造方法。   By bringing the graphite compound into contact with a subcritical fluid or supercritical fluid including a fluid in a liquid state at normal temperature and normal pressure, and then reducing the pressure applied to the subcritical fluid or supercritical fluid. A method for producing a exfoliated graphite compound, comprising exfoliating the above graphite compound. 常温で且つ常圧下にて液体状態の流体を含む流体中に黒鉛化合物を存在させて混合体を作製し、この混合体中の流体を高圧下にて加熱して亜臨界流体又は超臨界流体とすると共に上記黒鉛化合物を上記亜臨界流体又は上記超臨界流体に接触させた後、上記亜臨界流体又は上記超臨界流体に加わっている圧力を減圧することを特徴とする請求項1に記載の薄片化黒鉛化合物の製造方法。   A mixture is prepared by allowing a graphite compound to exist in a fluid containing a fluid in a liquid state at normal temperature and normal pressure, and the fluid in the mixture is heated under high pressure to form a subcritical fluid or supercritical fluid. The flake according to claim 1, wherein the pressure applied to the subcritical fluid or the supercritical fluid is reduced after the graphite compound is brought into contact with the subcritical fluid or the supercritical fluid. A method for producing a graphite oxide compound. 亜臨界流体又は超臨界流体中に黒鉛化合物を供給して上記黒鉛化合物を上記亜臨界流体又は上記超臨界流体に接触させた後、上記亜臨界流体又は上記超臨界流体に加わっている圧力を減圧することを特徴とする請求項1に記載の薄片化黒鉛化合物の製造方法。   After supplying the graphite compound into the subcritical fluid or supercritical fluid and bringing the graphite compound into contact with the subcritical fluid or supercritical fluid, the pressure applied to the subcritical fluid or supercritical fluid is reduced. The method for producing a exfoliated graphite compound according to claim 1. 亜臨界流体又は超臨界流体が、常温で且つ常圧下にて液体状態の流体と、常温で且つ常圧下にて気体状態の流体とを含む流体の亜臨界流体又は超臨界流体であることを特徴とする請求項1乃至請求項3の何れか1項に記載の薄片化黒鉛化合物の製造方法。   The subcritical fluid or supercritical fluid is a subcritical fluid or supercritical fluid that includes a fluid in a liquid state at normal temperature and normal pressure and a fluid in a gas state at normal temperature and normal pressure. The method for producing an exfoliated graphite compound according to any one of claims 1 to 3.
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