[0002] 石墨（graphite）為一種實質上不含氫、或含有少量氫的結晶體，其係具有碳原子藉由sp2
混成軌域之共價鍵形成為六方晶格狀的1原子厚度之二維網路分子（石墨烯）層合而成的構造。石墨烯或石墨係具有由存在於其面上之π電子所產生的導電性、源於較輕之碳原子彼此強固地鍵結而成之共價鍵結晶的高熱傳導性、或平面方向之高彈性模數等特殊的物性，尤其是具有源於石墨平面方向之共價鍵結晶的物性的加工成形體，於產業上極有價值。 [0003] 就石墨之加工成形體而言，各向同性石墨成形體係廣為人知。各向同性石墨成形體係由石油、煤原料之焦炭所製造，以原料焦炭經粉碎而成的粉末，與焦炭製造時以副產物獲得的煤焦瀝青等作為黏合劑，將彼等混合，而將稱為揉捏品之數十～數百μm的粉碎物作為成形原料使用。將此成形原料以冷均壓法（CIP）或擠出成形法、模製成形法等進行成形，可得到成形物，其後，將成形物在1000℃附近的溫度進行燒結，一邊使揮發分蒸發，一邊使焦炭與黏合劑合而為一。由於因此燒成脫離的揮發分而生成空孔，從而，以煤焦瀝青予以含浸，再度進行燒成而進行碳化，並進一步藉由對此經碳化之成形物進行通電，使其產生焦耳熱，於3000℃附近的溫度進行燒成、結晶化，可得到各向同性石墨成形體。 [0004] 經過如以上之程序，可得到以石墨構成的各向同性石墨成形體，但此係在製作成形物時僅單純鋪滿各向異性較小的焦炭粉末，因此形成之成形體內部的一個個石墨結晶係朝向四面八方，以微觀觀察成形體則其為等向性，從而稱為“各向同性”石墨。以擠出成形或模製成形法，雖可產生某種程度的各向異性，但離石墨結晶整齊配向的狀態仍極遙遠。 [0005] 因此，各向同性石墨並非大幅反映在石墨烯面方向以網狀形成共價鍵，且在與石墨烯面垂直之方向以凡得瓦力層合而成之具有各向異性的石墨結晶之性質。實際上，大幅取決於結晶構造的物性之熱傳導性，相對於石墨單晶具有約2000W/（m・K）之超高熱傳導性，各向同性石墨為數百W/（m・K）左右。 [0006] 相對於此，作為具有高配向之石墨結晶的石墨成形體，有可由高分子製作的高配向性熱分解石墨。相對於單純鋪滿原料粉碎物並予以碳化、石墨化所製造的各向同性石墨，由高分子製作的高配向性熱分解石墨能藉由以聚醯亞胺等經配向控制之高分子薄膜為原料，並將聚醯亞胺成形物在1500℃附近碳化、在3000℃附近石墨化，而製作高度配向的石墨成形體。例如片狀的高配向性熱分解石墨成形體，係石墨於平面方向高度配向，其熱傳導率係接近單晶石墨的性能。 [0007] 惟，為製作高配向性石墨，則須控制聚醯亞胺的初始配向，實際上以聚醯亞胺控制配向，而實現石墨成形體者為由厚度數十μm之聚醯亞胺薄膜製作的石墨片、或僅為其層合物，由此製法並無法自由地形成高配向性之石墨。 [0008] 如此，就以往石墨成形體，雖可較自由地成形，惟其主流為並無法充分發揮源於石墨結晶構造之物性的各向同性石墨，與雖為高配向但不易控制原料高分子的初始配向，而無法自由地成形的高配向性熱分解石墨。相對於此等以往石墨成形體之製法，若可由構成石墨的石墨烯分子建構出石墨結晶，而製作高配向性之石墨成形體，則無須使用：特地使用雜質較多的石油、煤原料，且需要多項步驟的各向同性石墨之製法、或為了確保形成之石墨成形體的配向性，而以非為碳材料之聚醯亞胺薄膜為原料的高配向性熱分解石墨之製法，而成為理想的石墨成形體之製造方法才是。 [0009] 石墨烯係指理想上由石墨一層層剝離而成的層狀化合物。於此，係包含一層至數十層者地稱為石墨烯粒子。純粹的石墨烯粒子，由於對溶媒等無親和性，若無分散劑，則僅能以極低濃度分散，對溶媒的分散性極低；因此，為製作成形體，便需要極大量的溶媒，而不實際。若減少使用之溶媒，則石墨烯粒子彼此瞬間凝聚，而成為配向性極差的凝聚物。又，若大量使用分散劑，自然而然彼等便成為雜質，而無法發揮石墨特有的性能。 [0010] 因此，作為用來由石墨烯分子製作石墨成形體之最有前景的石墨烯材料，可舉出氧化石墨烯。就氧化石墨烯而言，藉由對石墨烯的平面賦予羥基、環氧基、羰基或羧基等的親水性含氧基，可顯著提升其對水或一部分有機溶媒的分散性。因此，製作石墨結晶時無須使用可能成為雜質的分散劑等，即可使氧化石墨烯以層合達一分子層至數十層的狀態分散於溶媒中。藉由將此氧化石墨烯分散體成形，並去除溶媒，可製作成形物。 [0011] 再者，經分散之狀態的氧化石墨烯粒子的厚度為1nm以下～數nm，而另一方面氧化石墨烯平面方向的直徑則長達數μm，厚度方向與平面方向之粒徑的縱橫比高達1萬，因此藉由朝厚度方向整齊地層合，再去除溶媒可得配向性極優良成形物。 [0012] 惟，氧化石墨烯的平面結晶性會因賦予含氧基而喪失，故需使其還原、結晶化為石墨。例如，於非專利文獻1中，為使其還原、結晶化，而在1600～2850℃進行30分鐘熱處理。又，生成之石墨的熱傳導性，所記載之最高者為1434W/（m・K），係與高配向性熱分解石墨為同等水準，可知可形成高配向性之石墨成形體。 [0013] 然而，實際上由此氧化石墨烯製作的石墨成形體，為達高配向性之高物性，而從外部進行3000℃附近的熱處理，而此處理係與同樣為高配向性石墨成形體之由聚醯亞胺製作的高配向性熱分解石墨相同，從而仍舊為工業上負擔較大的製法。 [0014] 因此，作為進一步減少能量負擔地將氧化石墨烯成形體還原・結晶化而製作石墨成形體的方法，有前景者為藉由通電來進行電阻加熱（亦稱通電加熱）之方法，其屬各向同性石墨之石墨化步驟中所使用之從內部加熱的自發熱方式。氧化石墨烯會因導入含氧基，而使其π電子共軛系統遭破壞；從而，與石墨烯相比，其電阻極高，但與高分子或橡膠等的一般絕緣材料相比則電阻較低，因此，藉由施加某種程度的電壓，可流通電流，且藉由其高電阻，可使其瞬間發熱至超高溫。非專利文獻2中揭示，藉由對氧化石墨烯通電，1分鐘以內可使其還原與結晶化。 [0015] 然而，如此可直接通電，藉由焦耳熱使其急遽形成高溫狀態一事，雖有可縮短燒結程序而有效率地形成石墨成形體的優點，但基於由氧化石墨烯製作可反映石墨結晶的性質之高配向性之石墨成形物的觀點，並不充分。 [先前技術文獻] [非專利文獻] [0016] [非專利文獻1] Adv.Mater.2014, 26, 4521-4526 [非專利文獻2] Nano Lett.2016, 16, 3616-3623[0002] Graphite is a kind of crystal that is substantially free of hydrogen or contains a small amount of hydrogen, which has carbon atoms formed by sp 2 covalent bonds into orbital domains to form a hexagonal lattice of one atom thickness of two A layered structure of dimensional network molecules (graphene). Graphene or a graphite system has conductivity derived from π electrons existing on its surface, high thermal conductivity of covalent bond crystals derived from lighter carbon atoms strongly bonded to each other, or high planarity Special physical properties such as elastic modulus, especially processed shaped bodies with physical properties derived from covalent bond crystals originating in the plane direction of graphite, are extremely valuable in the industry. [0003] As for a processed graphite molded body, an isotropic graphite molding system is widely known. The isotropic graphite forming system is made of coke made from petroleum and coal raw materials. The raw material coke is pulverized, and the coal coke pitch obtained as a by-product during coke production is used as a binder. A pulverized product of several tens to several hundreds μm called a kneaded product is used as a molding raw material. This molding raw material is molded by a cold equalizing method (CIP), an extrusion molding method, a molding method, or the like to obtain a molded product. Thereafter, the molded product is sintered at a temperature of about 1000 ° C while the volatile content is increased. Evaporate the coke and binder into one. As a result of burning off the volatile components, voids are formed, so that the coal coke pitch is impregnated, and then firing is performed for carbonization, and the carbonized formed article is further energized to generate Joule heat, By firing and crystallization at a temperature around 3000 ° C, an isotropic graphite molded body can be obtained. [0004] Through the above procedure, an isotropic graphite formed body made of graphite can be obtained, but this is simply covered with coke powder with less anisotropy during the production of the formed article, so the inside of the formed formed body Graphite crystals are oriented in all directions, and when the formed body is viewed microscopically, it is isotropic, so it is called "isotropic" graphite. Extrusion or molding can produce a certain degree of anisotropy, but it is still far from the state where the graphite crystals are neatly aligned. [0005] Therefore, anisotropic graphite is not significantly reflected in the direction of the graphene surface to form a covalent bond in a network shape, and is laminated with van der Waals in the direction perpendicular to the graphene surface. Crystal properties. Actually, the thermal conductivity greatly depends on the physical properties of the crystal structure. It has ultra-high thermal conductivity of about 2000 W / (m · K) compared to graphite single crystals, and isotropic graphite is about several hundred W / (m · K). [0006] On the other hand, as a graphite molded body having graphite crystals with high alignment, there is high alignment pyrolytic graphite made of a polymer. Compared to isotropic graphite, which is simply covered with crushed material and carbonized and graphitized, high-alignment thermally decomposable graphite made of high-molecular polymers can be obtained by using polymer-oriented thin films such as polyimide. The raw material was carbonized at around 1500 ° C and graphitized at around 3000 ° C to produce a highly oriented graphite formed body. For example, a sheet-shaped highly-aligned pyrolytic graphite formed body is highly aligned in the planar direction, and its thermal conductivity is close to the performance of single crystal graphite. [0007] However, in order to make highly oriented graphite, it is necessary to control the initial orientation of polyimide. Actually, the orientation is controlled by polyimide, and the graphite shaped body is made of polyimide having a thickness of several tens of μm. A graphite sheet made of a thin film, or only a laminate thereof, cannot be freely formed into graphite with high alignment by this manufacturing method. [0008] In this way, although the conventional graphite formed body can be formed relatively freely, its mainstream is isotropic graphite that does not fully utilize the physical properties derived from the graphite crystal structure, and it has high alignment but is not easy to control the raw material polymer. Highly oriented thermally decomposable graphite that is initially aligned but cannot be freely formed. In contrast to these conventional methods for manufacturing graphite formed bodies, if graphite crystals can be constructed from the graphene molecules constituting graphite, and high-alignment graphite formed bodies are not required: special use of petroleum and coal raw materials with large impurities, and A method for producing isotropic graphite that requires multiple steps, or a method for producing highly oriented pyrolytic graphite using a polyimide film that is not a carbon material as a raw material in order to ensure the orientation of the formed graphite formed body, is ideal. The manufacturing method of the graphite formed body is. [0009] Graphene refers to a layered compound that is ideally made by exfoliating graphite layer by layer. Here, those containing one to several dozen layers are called graphene particles. Pure graphene particles have no affinity for solvents, etc. If there is no dispersant, they can only be dispersed at very low concentrations, and the dispersibility to solvents is extremely low. Therefore, in order to make shaped bodies, a very large amount of solvent is required. Not practical. When the used solvent is reduced, the graphene particles instantly aggregate with each other, and become agglomerates with extremely poor alignment. In addition, if a large amount of dispersant is used, they naturally become impurities, and the properties peculiar to graphite cannot be exhibited. [0010] Therefore, as the most promising graphene material for producing a graphite shaped body from graphene molecules, graphene oxide can be mentioned. For graphene oxide, by imparting a hydrophilic oxygen-containing group such as a hydroxyl group, an epoxy group, a carbonyl group, or a carboxyl group to the plane of the graphene, the dispersibility of the graphene oxide in water or a part of the organic solvent can be significantly improved. Therefore, it is not necessary to use a dispersant or the like that may become an impurity when preparing graphite crystals, and the graphene oxide can be dispersed in a solvent in a state of being laminated to one molecular layer to several tens of layers. By molding this graphene oxide dispersion and removing the solvent, a molded article can be produced. [0011] Furthermore, the thickness of the graphene oxide particles in a dispersed state is 1 nm to several nm, while the diameter of the graphene oxide in the planar direction is as long as several μm. The aspect ratio is as high as 10,000. Therefore, by laminating them neatly in the thickness direction and removing the solvent, a molded article with excellent alignment can be obtained. [0012] However, since the planar crystallinity of graphene oxide is lost due to the oxygen-containing group, it needs to be reduced and crystallized into graphite. For example, in Non-Patent Document 1, in order to reduce and crystallize, heat treatment is performed at 1600 to 2850 ° C for 30 minutes. In addition, the highest thermal conductivity of the generated graphite is 1434 W / (m · K), which is at the same level as the highly oriented thermally decomposable graphite, and it can be seen that a highly oriented graphite molded body can be formed. [0013] However, in order to achieve the high physical properties of the graphite formed body produced from the graphene oxide, a heat treatment near 3000 ° C. is performed from the outside, and this treatment is similar to the highly formed graphite formed body. It is the same as the high-orientation pyrolytic graphite made of polyimide, so it is still a manufacturing method with a large industrial burden. [0014] Therefore, as a method for producing a graphite molded body by reducing and crystallizing the graphene oxide molded body while further reducing the energy burden, a promising method is a method of resistance heating (also referred to as conductive heating) by applying electricity, which It belongs to the self-heating method used in the graphitization step of isotropic graphite. Graphene oxide will destroy its π-electron conjugated system due to the introduction of oxygen-containing groups; therefore, its resistance is extremely high compared to graphene, but it is more resistance than ordinary insulating materials such as polymers or rubber Low, therefore, by applying a certain level of voltage, current can flow, and with its high resistance, it can instantly heat up to extremely high temperatures. Non-patent document 2 discloses that by applying electricity to graphene oxide, it can be reduced and crystallized within 1 minute. [0015] However, it is possible to directly apply electricity in this way, and to rapidly form a high-temperature state by Joule heat. Although there is an advantage that the sintering process can be shortened and a graphite formed body can be efficiently formed, based on the production of graphene oxide, it can reflect graphite crystal The viewpoint of a highly shaped graphite molded article is not sufficient. [Prior Art Literature] [Non-Patent Literature] [0016] [Non-Patent Literature 1] Adv. Mater. 2014, 26, 4521-4526 [Non-Patent Literature 2] Nano Lett. 2016, 16, 3616-3623
[實施發明之形態] [0032] 本發明之石墨成形體之製造方法係以氧化石墨烯為原料的石墨成形體之製造方法，且包含：藉由通電來進行電阻加熱之步驟，與進行加壓之步驟。此特徵為各請求項之發明所共有或對應的技術特徵。 [0033] 就本發明之實施態樣，基於提升氧化石墨烯分子間之共價鍵形成的效率性觀點，較佳為同時進行前述藉由通電來進行電阻加熱之步驟與前述進行加壓之步驟。又，基於展現本發明之效果的觀點，亦較佳為個別進行前述藉由通電來進行電阻加熱之步驟與前述進行加壓之步驟。 [0034] 再者，於本發明中，前述進行加壓之步驟中對氧化石墨烯的施加壓力較佳為50MPa以上，更佳為100MPa以上。藉此，可獲得提高石墨結晶的配向性之效果。 [0035] 又，於本發明中，石墨成形體的熱傳導率較佳為1000W/（m・K）以上，更佳為1500W/（m・K）以上。 [0036] 就本發明之實施態樣，石墨成形體較佳為石墨片。 [0037] 以下，就本發明與其構成要素、及用來實施本發明的形態・態樣進行詳細的說明。此外，於本案中，「～」係以包含其前後所記載的數值作為下限值及上限值的意義使用。 [0038] 以下，就本發明與其構成要素、及用來實施本發明的形態・態樣進行詳細的說明。 [0039] 《石墨成形體之製造方法》 本發明之石墨成形體之製造方法係以氧化石墨烯為原料的石墨成形體之製造方法，且包含：藉由通電來進行電阻加熱之步驟，與進行加壓之步驟。 [0040] 氧化石墨烯亦可成形為所要之形狀。例如，可製作使將石墨以強氧化劑氧化而製作之氧化石墨烯分散於溶媒中所得的氧化石墨烯溶媒分散物，其後使用所要之形狀的模具將氧化石墨烯溶媒分散物成形，其後去除溶媒而製作氧化石墨烯的成形物。於本發明中，能以短時間且簡便的方法製造經過將其藉由通電進行電阻加熱之步驟，與進行加壓之步驟而具有高熱傳導率的石墨成形體。 [0041] ＜氧化石墨烯＞ 於本發明中，氧化石墨烯係指石墨烯經羧基、羰基、羥基及環氧基等含氧基修飾而成者。就本發明所使用的氧化石墨烯不特別限定，具有羧基、羰基、羥基或環氧基等含氧基之氧化石墨烯的含氧比率（原子%）較佳為24～50原子%的範圍內。若為24原子%以上，由溶媒分散性觀點係較佳；又，因鍵結特定量以上的上述含氧基，π共軛被切斷，使氧化石墨烯的電阻提高而較佳。又，若為50原子%以下，由還原・結晶化的效率性觀點係較佳。 [0042] （含氧比率的測定方法） 氧化石墨烯的含氧比率（原子%）能以X射線光電子分光法（X-ray Photoelectron Spectroscopy（以下亦稱XPS））來測定，為以O/（C+O）原子%表示的值。XPS測定條件如下。 [0043] 氧化石墨烯的含氧比率可使用ULVAC-PHI股份有限公司製QuanteraSXM來測定。就測定條件，作為X射線源係使用經單色化之Al-Kα射線，分光器係以如測定經清潔過的銀之Ag3
d5/2
峰時的峰半高寬為0.5eV以下之條件而設定，來進行測定。分光器的校正係依循ISO15472來進行。 [0044] ＜氧化石墨烯的面方向直徑＞ 氧化石墨烯為藉由對石墨進行氧化處理，使構成石墨的石墨烯剝離、氧化而成的層狀粒子。此層狀粒子的面方向直徑愈大，由導電性、熱傳導性、彈性模數或強度等物性之觀點而言愈佳。層的面方向直徑較佳為1μm以上，更佳為5μm以上，以氧化石墨烯溶媒分散體的分散狀態不會產生問題的範圍而言，再更佳為10μm以上。 [0045] ＜氧化石墨烯的厚度＞ 氧化石墨烯為藉由對石墨進行氧化處理，使構成石墨的石墨烯剝離、氧化而成的層狀粒子，其厚度為約0.34nm～數nm，不一定必須將全部剝離至單層，亦可視用途而定，在配向性不發生問題的範圍內形成數層～數十層之分散狀態。 [0046] ＜氧化石墨烯溶媒分散體＞ 氧化石墨烯可藉由將石墨、或多層石墨烯以強氧化劑氧化，在石墨烯粒子的面上或邊緣賦予環氧基、羥基、羰基及羧基等含氧基，而使其分散於溶媒中。其會充分分散於水中，於有機溶媒，亦與甲醇或乙醇、四氫呋喃（THF）等具有親水基之溶媒具有親和性，視用途而定，在成形性或配向性不發生問題的範圍內，採丙酮或甲基乙基酮（MEK）、二氯甲烷等其他的有機溶媒亦可製作分散體。 [0047] 氧化石墨烯溶媒分散物能以Hummers法、或將其改良之Modified Hummers法，基於周知文獻來製作。作為製作氧化石墨烯之周知文獻，可舉出例如W.S. Hummers., Journal of American Chemistry (1958) 1339、M.Hirata., Carbon 42 (2004) 2929等。 [0048] ＜氧化石墨烯成形物＞ 藉由從氧化石墨烯分散體中去除溶媒，可製作各種形狀的氧化石墨烯成形物。例如，若為片狀，藉由塗佈於基材並去除溶媒，可製作氧化石墨烯片。亦可作成厚度數nm的薄膜狀物。若為纖維狀，藉由使其從噴嘴的細管噴出，並去除溶媒，可製作氧化石墨烯纖維。又，一邊使用模具進行成形，一邊去除溶媒，亦可成形為所要之形狀，也能以3D印表機等製作所要之成形體。 [0049] ＜氧化石墨烯成形物的事前還原＞ 氧化石墨烯的還原係指使存在於氧化石墨烯中的含氧基，以水或氧氣、一氧化碳、二氧化碳、碳酸形式持續脫離的反應。若將氧化石墨烯片還原，則電阻率會持續減少。對氧化石墨烯成形物進行還原處理，視用途而定，亦可調整電阻率。藉由電阻率的調整，在藉由通電進行電阻加熱之步驟中，可調整流通電流量、或加熱溫度等條件。 [0050] 再者，相對於還原反應在約1000℃以下的溫度下進行，要使結晶化（石墨化）反應進行則需約1000℃以上，一般為2000℃以上的溫度。亦即，相對結晶化（石墨化）反應，還原反應的反應速度極快。因此，以抑制通電加熱時的膨脹之目的，亦可事先以溫和的條件進行還原反應。 [0051] 事先還原的方法無特別限制，可採用由氧化石墨烯獲得氧化石墨烯還原物的以往周知之方法。可舉出例如將氧化石墨烯加熱而予以還原的方法（熱還原）、使用肼或抗壞血酸等還原劑而予以還原的方法（化學還原）、對氧化石墨烯照光而予以還原的方法（光還原）、在電解質水溶液中將氧化石墨烯進行電解而予以還原的方法（電化學還原）等。作為製作氧化石墨烯還原物之周知文獻，可舉出例如Carbon 50 (2012) 3210等。 [0052] 《藉由通電來進行電阻加熱之步驟》 藉由對氧化石墨烯施加電壓而流通電流，可藉由氧化石墨烯的電阻所產生的焦耳熱使其自發熱。流動電流的方向不特別限定，可為直流或交流，可為定態電流或脈衝電流。流動電流或電壓的大小係隨薄片的大小或電阻而變動；較佳為以將氧化石墨烯片加熱至1000℃以上的方式而流通電流，較佳為以加熱至2000℃以上，更佳為2500℃以上的方式而流通電流。例如，較佳為以電流密度為100000 A/m2
以上，較佳為1000000 A/m2
以上，更佳為10000000 A/m2
以上，特佳為100000000 A/m2
以上的方式流通電流。可於源於石墨的電子密度之電流值的極限、或超過碳的昇華點之3600℃附近的範圍流通電流。 [0053] 《進行加壓之步驟》 於本發明中，除對氧化石墨烯進行通電加熱之步驟外，再組合將氧化石墨烯進行加壓之步驟，由此可大幅提高生成之石墨成形體的熱傳導率。茲認為這是因為，不僅可藉由加熱而獲得高配向性的石墨，而且藉由進行加壓，可進一步提高石墨中之石墨烯的配向性，而且可提高石墨的密度之故。 [0054] 加壓可與通電同時進行，亦可個別地，亦即在通電前或通電後進行。基於展現本發明之效果的觀點，加壓較佳與通電同時或在加熱後進行。再者，加壓較佳與通電同時進行。 [0055] 若與通電同時進行加壓，則以氧化石墨烯分子彼此因壓力而壓接之狀態進行通電，藉此能夠提升氧化石墨烯分子間之共價鍵形成的效率性。 [0056] 又，在通電前進行加壓，可提升氧化石墨烯分子彼此的密接性，而提升氧化石墨烯分子間之共價鍵形成的效率性。藉由在通電後進行加壓，則可顯著改善氧化石墨烯分子的配向性，而能夠展現高配向性石墨特有的物性。 [0057] 加壓裝置可使用壓機等，以面接觸施加，也可用輥予以夾持，而以線接觸施加。只要可施加所要的壓力，則形狀無限制。又，加壓方向可沿單軸施加，亦可由各方面施加。 [0058] 進行加壓之步驟中對氧化石墨烯的施加壓力較佳為1MPa以上，更佳為10MPa以上，再更佳為50MPa以上，特佳為100MPa以上。施加壓力的上限，就通用按壓裝置的能力而言為1000MPa左右。 [0059] 再者，於本發明中，前述藉由通電進行電阻加熱之步驟中的通電時間，由短時間內製造石墨成形體的觀點而言較佳為60秒以下，更佳為10秒以下，再更佳為3秒以下。通電時間的下限，只要為可提升石墨的結晶性，且不會對展現石墨特有的性能造成問題的範圍，則亦可為如脈衝之較短的電流施加。 [0060] 作為可同時進行通電與加壓的通用裝置，亦可使用放電電漿燒結裝置。於放電電漿燒結裝置中，可於成形體上下配置電極，並一邊通電一邊進行加壓。例如，能以電極夾住片狀體，一邊朝厚度方向流通電流使其自發熱，一邊進行加壓。只要將薄片層合並進行通電、加壓，則可簡便地製作薄片彼此壓接、接著而成的厚膜片、或塊體。 [0061] 作為在通電加熱前或後朝各方面施加壓力的裝置，亦可使用冷均壓裝置（CIP）、熱均壓裝置（HIP）。由於可由各方面施加壓力，可有效提升成形體的配向性。 [0062] 根據本發明，藉由焦耳熱所產生之自發熱與加壓，可促進氧化石墨烯的結晶化，而使石墨化進行。石墨化係指修復遭含氧基破壞之氧化石墨烯的sp2
共價鍵，同時使石墨烯彼此的層間隔成為與石墨結晶同等程度的0.34nm，並提升配向性。藉此石墨化，可使成形體展現與石墨單晶相近之物性。與以往之例如將聚醯亞胺進行外部加熱來製造片狀的高配向性石墨之情形相比，可格外地以短時間且簡便地，亦即有效率地製造。 [0063] ＜石墨成形體的形狀＞ 石墨成形體可藉由包含：藉由通電來進行電阻加熱之步驟，與進行加壓之步驟的製造方法來製造成形為所要之形狀的氧化石墨烯成形物。就其形狀，可較佳適用於片狀、纖維狀、框體形狀及薄膜形狀等。 [0064] ＜片狀石墨成形體＞ 作為片狀成形體，可舉出石墨片。石墨係指多個石墨烯層合而成之構造，層間係以較弱的凡得瓦力鍵結。石墨烯係指碳原子經共價鍵形成為六方晶格狀的1原子厚度之二維網路化合物。嚴格說來石墨係僅由sp2
碳原子所構成，自實際上係具有sp3
碳原子或空孔、雜原子等的缺陷；包含此等缺陷者亦稱石墨。於本發明中，石墨片係表示由石墨所構成的片狀物體。 [0065] 作為高配向性石墨片的用途，可舉出熱擴散片。隨著智慧型手機或平板電腦、筆記型電腦內之中央處理單元（CPU）的高性能化、多核心化，發熱量亦增大，而為了防止電子零件的故障、及減輕使用者因高溫所引起的不適感，在薄型之裝置中放熱空間不足的情況下，便需要可將由電子零件所產生的熱迅速地朝片體平面方向擴散之具有超高熱傳導性的片構件。高配向性石墨片係具有成為通用金屬中顯示最高性能的銅（401W/（m・K））之數倍的熱傳導性，產業上價值極高。惟，目前工業上廣泛使用之石墨片的製法，僅有前述之由聚醯亞胺製作的高配向性熱分解石墨，仍舊是採用工業上負擔較大的製程。若採用本發明之製造方法，則可廉價地製作高熱傳導性的石墨片，產業上極有價值。 [0066] ＜纖維狀石墨成形體＞ 藉由對將氧化石墨烯成形為纖維狀者，應用本發明之製造方法，可製作碳纖維。以往碳纖維之製程有1）將由高分子或石油原料所製作的纖維前驅物，以200～300℃的熱處理予以耐燃化・不熔化之步驟、2）將經耐燃化之纖維前驅物在1500℃附近進行熱處理之碳化步驟、3）進一步將經碳化之纖維，在2000℃至3000℃的溫度下進行熱處理之石墨化步驟，其後之表面處理、或聚合物塗敷等的步驟；藉由將以氧化石墨烯為原料的氧化石墨烯纖維作成碳纖維製造之前驅物，無需經過耐燃化・不熔化步驟，即可轉移至碳化・石墨化步驟，且在石墨化步驟中，亦可有效率地進行結晶化反應。對於以往之由高分子之聚丙烯腈或源於石油原料之瀝青經紡絲而成的纖維前驅物所製作的碳纖維，首先需要稱為耐燃化、不熔化步驟之緩緩地持續加溫燒結的製程，俾可耐受高溫熱處理。 [0067] 於此以往的步驟中，若急驟進行高溫處理則前驅物會發生熔解，因此便在耐燃化・不熔化步驟中，花費數十分鐘之較長的時間來進行燒結。然而，就本發明較佳態樣，只要使用由氧化石墨烯製作的纖維前驅物，則不會如高分子般發生熔解，因此亦可進行如急驟超過2000℃的高溫處理。又，碳纖維若於其構造體內無缺陷，則會形成極高強度的材料；另一方面，若存在有空隙或間隙等缺陷，則會以其為起點而發生脆性破壞，因此，透過應用本發明之藉由通電來進行電阻加熱之步驟與進行加壓之步驟，可有效率地使石墨化反應進行，並可抑制空隙的生成等，於產業上極有價值。 [0068] ＜石墨框體＞ 氧化石墨烯即使未完全溶解於溶媒中，也能製作以一分子層～數十層之狀態分散的溶液，因此，透過使用所要之形狀的模具，並使溶媒蒸發，可較自由地進行成形。進一步藉由對製作之成形體應用本發明之製程，可製作具有極高強度、高熱傳導等的高配向性石墨特有之性質的成形體，而能夠應用於各種框體、成形體，於產業上極有價值。 [0069] ＜石墨散熱片＞ 根據本發明之石墨成形體之製造方法，可有效率地製作以石墨構成的散熱片。視需求以3D印表機等亦可製作小型散熱片等。 [0070] ＜薄膜石墨（石墨烯）片成形體＞ 本發明之石墨成形體之製造方法，對於薄膜形狀的石墨亦可適用。例如，藉由將氧化石墨烯片以奈米級厚度製成膜，並進行還原、結晶化，亦可製作透明導電膜。惟，於此也是，僅進行通電加熱，會因產生的氣體而使膜面變得雜亂，而無法製作所要之高結晶的透明導電膜。透過應用本發明之製造方法，則可製作導電性極高、呈平滑且為透明的膜。目前所使用的透明導電膜為氧化銦錫（ITO），惟因銦為稀有金屬等，而極力尋求替代性材料。 [0071] 若為氧化石墨烯，則原料為石墨，存在於地球上。因此，吾人便積極從事石墨烯奈米片之透明導電膜的開發，就獲得高結晶性的石墨烯之目的，採用化學氣相沉積（CVD）而進行的石墨烯合成成為主流。若應用本發明之藉由通電來進行電阻加熱之步驟與進行加壓之步驟，則可由經簡便之塗佈製膜而得的氧化石墨烯片，於短時間簡便地製作屬石墨烯透明導電膜的石墨烯片，於產業上極有價值。 [0072] 此外，薄膜石墨（石墨烯）片亦可利用作為阻氣薄片。氧化石墨烯會因氧化反應而於平面生成空孔等，藉由本發明之通電加熱進行之結晶化，形成sp2
共價鍵、修復空孔，同時因藉由加壓所致之提升配向性，可有效率地製作透氣性極低的阻氣薄片。 [0073] ＜氧化石墨烯片的製作＞ 氧化石墨烯片可藉由塗佈氧化石墨烯溶媒分散體成某一定的厚度，並使溶媒乾燥來製作。只要可塗佈成一定的厚度並使其乾燥，則亦可於膜質不產生問題的範圍內採用任何塗佈方法。例如，有澆鑄製膜、過濾製膜、浸漬塗佈、旋轉塗佈、噴霧塗佈等。又，氧化石墨烯片可藉由塗佈於玻璃基板或樹脂基材而予以剝離。在可剝離氧化石墨烯片的範圍內，基板或基材可使用任何材料。 [0074] ＜氧化石墨烯片的還原、結晶化＞ 可利用進行通電加熱之步驟及進行加壓之步驟，進行氧化石墨烯片的還原、結晶化而製作石墨片。作為朝厚度方向進行通電加熱的方法，可一邊以壓機予以夾持，一邊施加電壓，亦可透過以二個輥予以夾持，並對輥施加電壓，而一邊以線接觸施加壓力予以運送，一邊朝厚度方向流通電流。又，亦可使用可一邊施加壓力一邊通電的放電電漿燒結裝置等。朝平面方向通電、加壓時，亦可對試樣的兩端施加電壓而通電，並對通電部由厚度方向使用壓機與間隔物等施加壓力。也能以二個輥夾住薄片而予以運送，同時，一邊準備相隔離的另一對輥，並對相隔離的輥間施加電壓而朝片體平面方向通電，一邊運送薄片。亦可一邊朝片體平面方向通電，一邊使用別的一對輥，來對通電部施加壓力。 [0075] 壓力可與通電同時施加，亦可個別地，亦即在通電前或後進行。 《石墨成形體的物性》 ＜熱傳導率＞ 作為表示導熱性能的物理量，有熱傳導率。熱傳導率（W/（m・K））係以熱擴散率（m2
/s）、比熱容量（J/（kg・K））、密度（kg/m3
）的積表示。藉由分別測定熱擴散率、比熱容量、密度，可算出熱傳導率。 [0076] ＜石墨成形體的熱傳導率＞ 通用金屬中具有最高熱傳導率者為銅，其熱傳導率為401W/（m・K）。從而，具有超越銅的熱傳導率且能簡便地製作石墨成形體的製造方法，於產業上有價值。再者，在提供具有1000W/（m・K）以上的熱傳導率之石墨成形體的手段中，現況在於僅有經約3000℃附近之外部加熱的石墨片被工業化，從而本發明之製作具有1000W/（m・K）以上的熱傳導率之石墨成形體的製造方法，於產業上極有價值。又，若為1500W/（m・K）以上，則為接近單晶石墨的熱傳導率之性能，於產業上特別有價值。熱傳導率係愈高愈佳，因此其上限無特別限制，惟石墨單晶的熱傳導率的理論值為約2000W/（m・K）左右。 [0077] 又，由熱擴散片等具有產業上通用性而言，石墨成形體較佳為石墨片。 [實施例] [0078] 以下，舉出實施例對本發明具體地加以說明，惟本發明非限定於此等。此外，在實施例中係使用「份」或「%」之標示，除非特別事先敘明，否則係表示「質量份」或「質量%」。 [0079] [實施例1] ＜氧化石墨烯水分散體1的調製＞ 將東京化成工業（股）之石墨烯奈米薄板（厚度6～8nm、寬5μm）10g、硝酸鈉7.5g裝入燒瓶中，對其添加濃硫酸621g。將燒瓶浸漬於冰浴中，一邊攪拌，一邊以溶液溫度不超過20℃的方式逐次少量地添加過錳酸鉀45g。其後，回升至室溫，攪拌14天後，對其添加1L的5質量%硫酸並攪拌1小時。進而，對其添加30質量%的過氧化氫水30g，攪拌1小時。添加調整成硫酸的濃度為3質量%、過氧化氫水的濃度為0.5質量%的混合溶液1L加以稀釋。將此溶液進行離心分離（5000rpm、15分鐘），去除上澄液，添加同樣的混合溶液，重複進行離心分離10次。以純水進行同樣的離心分離10次，於第10次捨棄上澄液後，添加250mL的純水而製成氧化石墨烯水分散體1。 [0080] ＜氧化石墨烯片1的製作＞ 將氧化石墨烯水分散體1以調整成1.5mm之間隙的塗佈器塗佈於黏貼於玻璃基板的25μm之PET（聚對苯二甲酸乙二酯）薄膜上。於50℃使其乾燥10小時後，由PET薄膜剝離，而得到氧化石墨烯片1（厚度44μm）。氧化石墨烯片1的含氧比率為49原子%。含氧比率（原子%）係以前述之XPS測定。 [0081] ＜石墨片1的製作＞ 在氬氣氣流下，對切成寬5mm、長50mm的氧化石墨烯片1之中央部的長度30mm的區域，隔著間隔物，使用壓機施加10MPa的壓力。在施加壓力的狀態下，對氧化石墨烯的兩端部施加電壓，以15A流通電流30秒，而製成作為石墨成形體的片狀之石墨片1。 [0082] ＜石墨片2～4的製作＞ 除在石墨片1的製作中，如表1變更進行加壓之步驟中的壓力以外，係與石墨片1的製作同樣地進行製作，而得到石墨片2～4。 [0083] ＜石墨片5的製作＞ 在氬氣氣流下，對切成寬5mm、長50mm的氧化石墨烯片1的兩端部施加電壓，以15A流通電流30秒後，使用壓機，在室溫下以10MPa施加壓力30分鐘，而得到作為石墨成形體的片狀之石墨片5。 [0084] ＜石墨片6～8的製作＞ 除在石墨片5的製作中，如表1變更進行加壓之步驟中的壓力以外，係與石墨片5的製作同樣地進行製作，而得到石墨片6～8。 [0085] ＜石墨片9的製作＞ 在氬氣氣流下，對切成寬5mm、長50mm的氧化石墨烯片1的兩端部施加電壓，將通電15A的電流30秒後者，作成石墨片9，而作為比較例。 [0086] ＜石墨片10的製作＞ 在氬氣氣流下，將氧化石墨烯片1以加熱爐昇溫至2500℃後，保持30分鐘。降溫後，將在室溫下使用壓機以200MPa施加壓力30分鐘後者，作成石墨片10，而作為比較例。 [0087] 《石墨片的評定》 ＜熱傳導率的測定＞ 熱傳導率係以下式表示，係藉由分別測定熱擴散率、比熱容量、密度而算出。 [0088] ＜通電加熱時的溫度＞ 以放射溫度計測定通電加熱條件下之石墨片編號1～9的溫度的結果，確認達2000℃以上的溫度。具體而言為2000～3000℃的溫度範圍內。 [0089] 熱傳導率=熱擴散率×比熱容量×密度 熱擴散率係以ADVANCE RIKO（股）之Laser Pit測定，比熱容量係以示差掃描式熱量計（DSC6220：Hitachi High-Technologies（股）製）測定，密度則是測定薄片的質量與體積，而算出上述製作之各石墨片在溫度23℃下的熱傳導率。將結果示於表1。 [0090] [表1][0091] 根據表1，屬本發明之片狀之石墨成形體的石墨片，與比較例相比，熱傳導率較高，且可於短時間有效率地製造。 [0092] 於本發明中，係以氧化石墨烯為起始原料，藉由通電加熱而於整個成形體有效率地形成sp2
共價鍵，並藉由加壓而使配向性提升，由此，可實現以往未實現之可由石墨烯材料增層式地有效率地製作高配向性之石墨成形體者；而此意指：可將作為氧化石墨烯的原料之豐富存在於地球上的石墨，在不損及結晶原本的性質下，視用途而定加工成各種形態。 [0093] 自以往以來，就氧化石墨烯而言，存在有諸多報導或專利文獻，而其大部分係著眼於2004年所發現之單層石墨烯的優良物性。本發明係有別於此主流，而是基於或許可藉由利用氧化石墨烯的溶媒分散能力、或成形時因高縱橫比所產生的配向能力，而有效率地製作工業上極有價值的高配向性之石墨成形體之見解。為了由氧化石墨烯有效率地製作高配向性之石墨成形體，僅需要乍看之下單純的通電加熱與加壓程序，而且透過使用此成形體，可首次展現高配向性之石墨成形體的優良物性。本發明堪稱為滿足所有為了製作高配向性石墨成形體所需之材料的成形性或配向性、製造的效率性之製造方法，可謂於產業上極有價值者。 [產業上可利用性] [0094] 本發明之石墨成形體之製造方法係以氧化石墨烯為原料的石墨成形體之製造方法，可提供一種可由氧化石墨烯，以短時間且簡便的方法製造高熱傳導率之石墨成形體的石墨成形體之製造方法。[Forms of Implementing the Invention] [0032] The method for manufacturing a graphite molded body of the present invention is a method for manufacturing a graphite molded body using graphene oxide as a raw material, and includes a step of resistance heating by applying electricity and pressurization. The steps. This feature is a technical feature common to or corresponding to the invention of each claim. [0033] According to an embodiment of the present invention, from the viewpoint of improving the efficiency of covalent bond formation between graphene oxide molecules, it is preferable to perform the aforementioned step of resistance heating by applying electricity and the aforementioned step of pressing at the same time. . From the viewpoint of exhibiting the effects of the present invention, it is also preferable to perform the aforementioned step of resistance heating by applying electricity and the aforementioned step of pressing individually. [0034] Furthermore, in the present invention, the pressure applied to the graphene oxide in the aforementioned step of applying pressure is preferably 50 MPa or more, and more preferably 100 MPa or more. Thereby, the effect of improving the orientation of the graphite crystal can be obtained. [0035] In the present invention, the thermal conductivity of the graphite molded body is preferably 1,000 W / (m · K) or more, and more preferably 1500 W / (m · K) or more. [0036] According to an embodiment of the present invention, the graphite formed body is preferably a graphite sheet. [0037] Hereinafter, the present invention, its constituent elements, and forms and aspects for implementing the present invention will be described in detail. In addition, in this case, "~" is used in the meaning which includes the numerical value described before and after it as a lower limit and an upper limit. [0038] Hereinafter, the present invention and its constituent elements, and forms and aspects for implementing the present invention will be described in detail. [0039] "Manufacturing method of graphite shaped body" The manufacturing method of graphite shaped body of the present invention is a method for manufacturing a graphite shaped body using graphene oxide as a raw material, and includes a step of resistance heating by applying electricity, and Steps of pressure. [0040] Graphene oxide can also be formed into a desired shape. For example, a graphene oxide solvent dispersion obtained by dispersing graphene oxide prepared by oxidizing graphite with a strong oxidizing agent in a solvent can be prepared, and then the graphene oxide solvent dispersion is formed using a mold having a desired shape, and then removed A molded product of graphene oxide was prepared by using a solvent. In the present invention, a graphite molded body having a high thermal conductivity can be produced in a short time and simply by passing through a step of resistance heating by applying electricity and a step of pressing. [0041] <Graphene Oxide> In the present invention, the graphene oxide refers to a graphene modified with an oxygen-containing group such as a carboxyl group, a carbonyl group, a hydroxyl group, and an epoxy group. The graphene oxide used in the present invention is not particularly limited, and the oxygen-containing ratio (atomic%) of the oxygen-containing graphene oxide having an carboxyl group, a carbonyl group, a hydroxyl group, or an epoxy group is preferably in a range of 24 to 50 atomic%. . If it is 24 atomic% or more, it is more preferable from the viewpoint of solvent dispersibility. Further, since the above-mentioned oxygen-containing group is bonded to a specific amount or more, the π conjugate is cut, and the resistance of graphene oxide is improved, which is preferable. Moreover, if it is 50 atomic% or less, it is preferable from the viewpoint of efficiency of reduction and crystallization. [0042] (Measurement Method of Oxygen Content Ratio) The oxygen content ratio (atomic%) of graphene oxide can be measured by X-ray Photoelectron Spectroscopy (hereinafter also referred to as XPS), and it is measured as O / ( C + O) Value expressed in atomic%. The XPS measurement conditions are as follows. [0043] The oxygen content ratio of graphene oxide can be measured using QuanteraSXM manufactured by ULVAC-PHI Co., Ltd. Regarding the measurement conditions, monochromatic Al-Kα rays were used as the X-ray source, and the spectroscope was such that the peak full width at half maximum when the Ag 3 d 5/2 peak of the cleaned silver was measured was 0.5 eV or less. The conditions are set and measured. The calibration of the spectroscope is performed in accordance with ISO15472. [0044] <Planar Direction Diameter of Graphene Oxide> Graphene oxide is a layered particle formed by oxidizing graphite to peel and oxidize graphene constituting graphite. The larger the diameter of the layered particles in the plane direction, the better it is from the viewpoints of physical properties such as electrical conductivity, thermal conductivity, elastic modulus, and strength. The diameter in the plane direction of the layer is preferably 1 μm or more, more preferably 5 μm or more, and in a range where the dispersion state of the graphene oxide solvent dispersion does not cause a problem, it is even more preferably 10 μm or more. [0045] <Thickness of Graphene Oxide> Graphene oxide is a layered particle formed by oxidizing graphite to peel and oxidize graphene constituting graphite, and its thickness is about 0.34 nm to several nm, which is not necessarily All of them must be peeled to a single layer, and depending on the application, a dispersed state of several to several tens of layers can be formed within a range in which the alignment problem does not occur. [0046] <Graphene oxide solvent dispersion> Graphene oxide can be oxidized with a strong oxidizing agent such as graphite or multi-layer graphene to give epoxy groups, hydroxyl groups, carbonyl groups, and carboxyl groups to the surface or edges of graphene particles. Oxygen and disperse it in the solvent. It will be fully dispersed in water, and will have an affinity with organic solvents, and also with solvents with hydrophilic groups such as methanol, ethanol, and tetrahydrofuran (THF). Depending on the application, within the range of no problems in formability or alignment, Dispersions can also be made from other organic solvents such as acetone, methyl ethyl ketone (MEK), and dichloromethane. [0047] The graphene oxide solvent dispersion can be produced by the Hummers method or a modified Hummers method based on a well-known literature. Examples of well-known documents for preparing graphene oxide include WS Hummers., Journal of American Chemistry (1958) 1339, M. Hirata., Carbon 42 (2004) 2929, and the like. [0048] <Graphene Oxide Molded Article> By removing the solvent from the graphene oxide dispersion, graphene oxide molded articles of various shapes can be produced. For example, in the case of a sheet shape, a graphene oxide sheet can be produced by coating on a substrate and removing a solvent. It can also be made into a thin film with a thickness of several nm. If it is fibrous, it can be ejected from a thin tube of a nozzle and the solvent can be removed to produce a graphene oxide fiber. In addition, while molding is performed using a mold, the solvent can be removed, and the molding can be formed into a desired shape, and a desired formed body can be produced by a 3D printer or the like. [Pre-Reduction of Graphene Oxide Molded Articles] The reduction of graphene oxide refers to a reaction in which the oxygen contained in graphene oxide is continuously desorbed in the form of water or oxygen, carbon monoxide, carbon dioxide, and carbonic acid. If the graphene oxide sheet is reduced, the resistivity will continue to decrease. The graphene oxide molded product is subjected to reduction treatment, and the resistivity may be adjusted depending on the application. By adjusting the resistivity, in the step of resistance heating by energization, conditions such as the amount of flowing current or heating temperature can be adjusted. [0050] In addition, the reduction reaction is performed at a temperature of about 1000 ° C. or lower, and the crystallization (graphitization) reaction needs to be performed at a temperature of about 1000 ° C. or higher, and generally a temperature of 2000 ° C. or higher. That is, compared to the crystallization (graphitization) reaction, the reaction rate of the reduction reaction is extremely fast. Therefore, for the purpose of suppressing the swelling at the time of energization heating, a reduction reaction may be performed in advance under mild conditions. [0051] The method of reducing in advance is not particularly limited, and a conventionally known method of obtaining a graphene oxide reduced product from graphene oxide can be used. Examples include a method of heating and reducing graphene oxide (thermal reduction), a method of reducing using a reducing agent such as hydrazine or ascorbic acid (chemical reduction), and a method of reducing graphene oxide by light (light reduction). A method (electrochemical reduction) in which graphene oxide is reduced by electrolysis in an aqueous electrolyte solution. Examples of well-known documents for the production of graphene oxide reduction products include Carbon 50 (2012) 3210 and the like. [0052] "Step of Resistive Heating by Energization" By applying a voltage to graphene oxide to flow a current, self-heating can be caused by the Joule heat generated by the resistance of graphene oxide. The direction of the flowing current is not particularly limited, and may be a direct current or an alternating current, and may be a steady state current or a pulse current. The magnitude of the flowing current or voltage varies with the size or resistance of the sheet; it is preferred to flow the current by heating the graphene oxide sheet above 1000 ° C, preferably by heating above 2000 ° C, more preferably 2500 A current of more than ℃. For example, preferably a current density of 100000 A / m 2 or more, preferably 1000000 A / m 2 or more, more preferably 10000000 A / m 2 or more, particularly preferably 100000000 A / 2 m above manner current flows. Current can flow from the limit of the current value derived from the electron density of graphite, or from a range around 3600 ° C that exceeds the sublimation point of carbon. [0053] "Step of Pressing" In the present invention, in addition to the step of electrically heating and heating graphene oxide, the step of pressing graphene oxide is combined, thereby greatly improving the graphite formed body. Thermal conductivity. It is thought that this is because not only graphite with high alignment can be obtained by heating, but also the orientation of graphene in graphite can be further improved by pressing, and the density of graphite can be increased. [0054] The pressurization can be performed simultaneously with the energization or individually, that is, before or after the energization. From the viewpoint of exhibiting the effects of the present invention, the pressing is preferably performed at the same time as the current is applied or after heating. The pressurization is preferably performed at the same time as energization. [0055] When pressurization is performed simultaneously with current application, the current is applied in a state where graphene oxide molecules are pressure-bonded to each other by pressure, thereby improving the efficiency of covalent bond formation between graphene oxide molecules. [0056] In addition, pressurization before energization can improve the adhesion between graphene oxide molecules and increase the efficiency of covalent bond formation between graphene oxide molecules. By pressurizing after energization, the orientation of graphene oxide molecules can be significantly improved, and physical properties peculiar to highly aligned graphite can be exhibited. [0057] The pressing device may be applied in a surface contact using a press or the like, or may be held by a roller and applied in a line contact. The shape is not limited as long as the desired pressure can be applied. The pressing direction may be applied along a single axis, or may be applied from various aspects. [0058] The pressure applied to the graphene oxide in the step of pressing is preferably 1 MPa or more, more preferably 10 MPa or more, even more preferably 50 MPa or more, and particularly preferably 100 MPa or more. The upper limit of the applied pressure is about 1000 MPa in terms of the capability of the general-purpose pressing device. [0059] Furthermore, in the present invention, the energization time in the step of resistance heating by energization is preferably 60 seconds or less, and more preferably 10 seconds or less, from the viewpoint of producing a graphite molded body in a short time. , And more preferably less than 3 seconds. As long as the lower limit of the energization time is in a range that can improve the crystallinity of graphite and does not cause problems in exhibiting graphite-specific properties, it can also be applied with a short current such as a pulse. [0060] A discharge plasma sintering device can also be used as a general-purpose device that can be energized and pressurized simultaneously. In a discharge plasma sintering apparatus, electrodes can be arranged above and below the formed body, and pressure can be applied while applying current. For example, the sheet-like body can be sandwiched between the electrodes, and can be pressurized while a self-heating current flows in the thickness direction. As long as the sheet layers are combined to be energized and pressurized, a thick film sheet or a block body in which the sheets are pressure-bonded to each other and then bonded can be easily produced. [0061] As a device that applies pressure to various aspects before or after energization heating, a cold equalizing device (CIP) and a hot equalizing device (HIP) can also be used. Since pressure can be applied from various aspects, the alignment of the formed body can be effectively improved. [0062] According to the present invention, by self-heating and pressure generated by Joule heat, crystallization of graphene oxide can be promoted and graphitization can be performed. Graphitization refers to repairing the sp 2 covalent bond of graphene oxide which is destroyed by oxygen, while making the interlayer distance of graphene to 0.34 nm, which is the same as that of graphite crystal, and to improve the alignment. By this graphitization, the formed body can exhibit physical properties similar to graphite single crystal. Compared with the conventional case where, for example, a polyimide is externally heated to produce a sheet-like high-alignment graphite, it can be produced in a short time and simply, that is, efficiently. [0063] <Shape of Graphite Molded Body> The graphite molded body can be manufactured into a graphene oxide molded article formed into a desired shape by a manufacturing method including a step of conducting resistance heating by applying electricity and a step of pressing. . As for its shape, it can be preferably applied to a sheet shape, a fibrous shape, a frame shape, and a film shape. [0064] <Flake-shaped graphite molded body> As the sheet-shaped molded body, a graphite sheet is mentioned. Graphite refers to a structure in which a plurality of graphene are laminated, and the layers are bonded by a weak van der Waals force. Graphene refers to a two-dimensional network compound of 1 atom thickness in which carbon atoms are covalently bonded to form a hexagonal lattice. Strictly speaking, the graphite system is only composed of sp 2 carbon atoms, and actually has defects such as sp 3 carbon atoms, pores, and heteroatoms; those containing these defects are also called graphite. In the present invention, a graphite sheet refers to a sheet-like object made of graphite. [0065] Examples of uses of the highly-aligned graphite sheet include a thermal diffusion sheet. As the central processing unit (CPU) in smart phones, tablets, and notebook computers has become more high-performance and multi-core, the amount of heat has also increased. In order to prevent the failure of electronic components and reduce the user's risk of high temperature When the discomfort caused is insufficient in a thin device, a sheet member having ultra-high thermal conductivity is required to rapidly diffuse the heat generated by the electronic components toward the plane of the sheet body. High-alignment graphite flakes have thermal conductivity several times that of copper (401W / (m · K)), which shows the highest performance among general-purpose metals, and is extremely valuable in the industry. However, at present, the graphite sheet widely used in the industry is the only high-alignment pyrolytic graphite made of polyimide, and it still uses an industrially burdensome process. According to the production method of the present invention, a graphite sheet having high thermal conductivity can be produced at low cost, which is extremely valuable in the industry. [0066] <Fibrous Graphite Molded Body> By forming graphene oxide into a fibrous shape, a carbon fiber can be produced by applying the production method of the present invention. The conventional carbon fiber manufacturing process includes 1) a step of flame-resistant and non-melting a fiber precursor made of a polymer or a petroleum raw material through a heat treatment at 200 to 300 ° C, and 2) a flame-resistant fiber precursor near 1500 ° C A carbonization step for heat treatment; 3) a graphitization step for further heat treatment of the carbonized fiber at a temperature of 2000 ° C. to 3000 ° C., followed by a surface treatment or polymer coating step; Graphene oxide as a raw material is used as a precursor for carbon fiber manufacturing. It can be transferred to the carbonization and graphitization step without undergoing a flame-resistant and non-melting step, and can be efficiently crystallized during the graphitization step.化 反应。 Reaction. For the previous carbon fibers made from polymer precursors of polymer polyacrylonitrile or asphalt derived from petroleum raw materials, firstly, it is necessary to slowly and continuously heat and sinter the so-called flame-resistant and non-melting steps. Process, 俾 can withstand high temperature heat treatment. [0067] In this conventional step, if the high-temperature treatment is performed rapidly, the precursor will be melted. Therefore, in the flame-resistant and non-melting step, it takes a long time of several tens of minutes to sinter. However, in a preferred aspect of the present invention, as long as a fiber precursor made of graphene oxide is used, it does not melt like a polymer, and therefore, it can also be subjected to a high temperature treatment such as suddenly exceeding 2000 ° C. In addition, if carbon fiber has no defects in its structure, it will form a very high-strength material. On the other hand, if there are defects such as voids or gaps, brittle failure will occur from the starting point. Therefore, by applying the present invention The step of resistance heating by applying electricity and the step of pressing can efficiently perform the graphitization reaction and suppress the generation of voids, which are extremely valuable in the industry. [0068] <Graphite Frame> Even if graphene oxide is not completely dissolved in the solvent, a solution dispersed in a state of one molecular layer to several tens of layers can be prepared. Therefore, by using a mold having a desired shape, the solvent is evaporated. , Can be more freely formed. Further, by applying the process of the present invention to the formed body, it is possible to produce a formed body having properties unique to highly alignable graphite, such as extremely high strength and high thermal conductivity, and it can be applied to various frames and formed bodies in industry. Extremely valuable. [0069] <Graphite Radiating Fin> According to the method for manufacturing a graphite molded body of the present invention, a radiation fin composed of graphite can be efficiently produced. 3D printers can also be used to make small heat sinks. [0070] <Thin-Film Graphite (Graphene) Sheet Shaped Body> The method for producing a graphite shaped body of the present invention is also applicable to thin-film shaped graphite. For example, a transparent conductive film can also be produced by forming a graphene oxide sheet into a nanometer-thick film, and performing reduction and crystallization. However, it is also here that the heating of the current only causes the film surface to become chaotic due to the generated gas, making it impossible to produce a desired highly crystalline transparent conductive film. By applying the manufacturing method of the present invention, a film having extremely high conductivity, smoothness, and transparency can be produced. The currently used transparent conductive film is indium tin oxide (ITO), but because indium is a rare metal, etc., it is actively seeking alternative materials. [0071] In the case of graphene oxide, the raw material is graphite and exists on the earth. Therefore, I am actively engaged in the development of transparent conductive films of graphene nano flakes. For the purpose of obtaining graphene with high crystallinity, graphene synthesis using chemical vapor deposition (CVD) has become the mainstream. If the steps of resistance heating and pressurization by applying electricity according to the present invention are applied, a graphene oxide sheet obtained by simple coating and film formation can be used to easily produce a graphene transparent conductive film in a short time. Graphene sheet is extremely valuable in the industry. [0072] In addition, a thin-film graphite (graphene) sheet can also be used as a gas barrier sheet. Graphene oxide will generate voids on the plane due to oxidation reaction. The crystallization by electric heating of the present invention will form sp 2 covalent bonds and repair voids. At the same time, the alignment will be improved by pressure. Gas barrier sheets with extremely low air permeability can be efficiently produced. [0073] <Production of Graphene Oxide Sheet> A graphene oxide sheet can be produced by coating a graphene oxide solvent dispersion to a certain thickness and drying the solvent. As long as it can be applied to a certain thickness and allowed to dry, any application method can be adopted within a range where the film quality does not cause a problem. Examples include cast film formation, filtration film formation, dip coating, spin coating, and spray coating. In addition, the graphene oxide sheet can be peeled off by being coated on a glass substrate or a resin substrate. Any material can be used for the substrate or the substrate within the range of the peelable graphene oxide sheet. [0074] <Reduction and Crystallization of Graphene Oxide Sheets> Graphite oxide sheets can be produced by reduction and crystallization of graphene oxide sheets by using a step of applying electric heating and a step of pressing. As a method of applying electric heating in the thickness direction, voltage can be applied while being clamped by a press, or can be conveyed by applying pressure to the rollers while being clamped by two rollers and applying voltage to the rollers. One side flows a current in the thickness direction. Alternatively, a discharge plasma sintering device or the like that can be energized while applying pressure can be used. When applying current or applying pressure in a planar direction, a voltage may be applied to both ends of the sample to apply current, and a pressure may be applied to the conducting portion from a thickness direction using a press and a spacer. The sheet can also be transported by sandwiching the sheet with two rollers, and at the same time, the sheet can be transported while preparing another pair of rollers that are separated from each other, and applying a voltage between the rollers that are separated from each other to energize the sheet. It is also possible to use another pair of rollers to apply pressure to the current-carrying part while energizing in the plane direction of the sheet body. [0075] The pressure may be applied at the same time as the power is applied, or it may be performed individually, that is, before or after the power is applied. "Physical properties of graphite formed body"<Thermalconductivity> As a physical quantity showing thermal conductivity, there is a thermal conductivity. Thermal conductivity (W / (m · K)) is expressed as the product of thermal diffusivity (m 2 / s), specific heat capacity (J / (kg · K)), and density (kg / m 3 ). By measuring the thermal diffusivity, specific heat capacity, and density separately, the thermal conductivity can be calculated. [0076] <Thermal Conductivity of Graphite Molded Body> Among the general-purpose metals, copper has the highest thermal conductivity, and its thermal conductivity is 401 W / (m · K). Therefore, it is industrially valuable to have a manufacturing method that can surpass the thermal conductivity of copper and can easily produce a graphite molded body. Furthermore, in the means for providing a graphite molded body having a thermal conductivity of 1000 W / (m · K) or more, the current situation is that only a graphite sheet heated externally at about 3000 ° C is industrialized, so that the production of the present invention has 1000 W A method for manufacturing a graphite molded body having a thermal conductivity of more than / (m · K) is extremely valuable in the industry. In addition, if it is 1500 W / (m · K) or more, it has a performance close to the thermal conductivity of single crystal graphite, and is particularly valuable in the industry. The higher the thermal conductivity, the better, so there is no particular upper limit, but the theoretical value of the thermal conductivity of the graphite single crystal is about 2000 W / (m · K). [0077] In terms of industrial applicability, such as a thermal diffusion sheet, the graphite molded body is preferably a graphite sheet. [Examples] [0078] Examples of the present invention will be specifically described below, but the present invention is not limited to these. In addition, in the examples, a "part" or "%" mark is used, and unless otherwise stated in advance, it means "mass part" or "mass%". [Example 1] <Preparation of graphene oxide aqueous dispersion 1> 10 g of graphene nano sheet (thickness 6-8 nm, width 5 μm) and 7.5 g of sodium nitrate of Tokyo Chemical Industry Co., Ltd. were charged into a flask. To this, 621 g of concentrated sulfuric acid was added. The flask was immersed in an ice bath, and while stirring, 45 g of potassium permanganate was successively added so that the solution temperature did not exceed 20 ° C. Thereafter, the temperature was returned to room temperature, and after stirring for 14 days, 1 L of 5 mass% sulfuric acid was added thereto, followed by stirring for 1 hour. Furthermore, 30 g of 30 mass% hydrogen peroxide water was added to this, and it stirred for 1 hour. 1 L of a mixed solution adjusted to a sulfuric acid concentration of 3% by mass and a hydrogen peroxide water concentration of 0.5% by mass was added and diluted. This solution was centrifuged (5000 rpm, 15 minutes), the supernatant solution was removed, the same mixed solution was added, and centrifugation was repeated 10 times. The same centrifugation was performed 10 times with pure water, and the supernatant was discarded at the 10th time, and then 250 mL of pure water was added to prepare a graphene oxide aqueous dispersion 1. [Production of Graphene Oxide Sheet 1] The graphene oxide aqueous dispersion 1 was coated on a 25 μm PET (polyethylene terephthalate) adhered to a glass substrate with an applicator adjusted to a gap of 1.5 mm. Ester) film. After drying at 50 ° C. for 10 hours, the PET film was peeled off to obtain a graphene oxide sheet 1 (thickness: 44 μm). The oxygen content of the graphene oxide sheet 1 was 49 atomic%. The oxygen ratio (atomic%) was measured by the aforementioned XPS. [0081] <Production of Graphite Sheet 1> An area of 30 mm in length at the central portion of the graphene oxide sheet 1 cut into a width of 5 mm and a length of 50 mm was placed under a argon gas stream with a spacer applied at a pressure of 10 MPa using a press. pressure. In a state where pressure was applied, a voltage was applied to both ends of the graphene oxide, and a current was passed at 15 A for 30 seconds to produce a sheet-like graphite sheet 1 as a graphite molded body. [0082] <Production of Graphite Sheet 2 to 4> Except in the production of graphite sheet 1, except that the pressure in the step of applying pressure was changed as shown in Table 1, production was performed in the same manner as in the production of graphite sheet 1, and graphite was obtained. Pieces 2 to 4. [Production of Graphite Sheet 5] Under an argon gas flow, a voltage was applied to both ends of the graphene oxide sheet 1 cut into a width of 5 mm and a length of 50 mm, and a current was passed at 15 A for 30 seconds. A pressure of 10 MPa was applied at room temperature for 30 minutes to obtain a sheet-like graphite sheet 5 as a graphite molded body. [0084] <Production of Graphite Sheets 6 to 8> The graphite sheet 5 was produced in the same manner as the production of the graphite sheet 5 except that the pressure in the step of applying pressure was changed as shown in Table 1 in the production of the graphite sheet 5. Pieces 6 to 8. [0085] <Production of Graphite Sheet 9> Under an argon gas flow, a voltage was applied to both ends of the graphene oxide sheet 1 cut into a width of 5 mm and a length of 50 mm, and a current of 15 A was applied for 30 seconds to form the graphite sheet 9 As a comparative example. [Production of Graphite Sheet 10] The graphene oxide sheet 1 was heated to 2500 ° C in a heating furnace under an argon gas flow, and then held for 30 minutes. After the temperature was lowered, a pressure was applied at 200 MPa for 30 minutes using a press at room temperature to prepare a graphite sheet 10 as a comparative example. [Evaluation of Graphite Sheet] <Measurement of Thermal Conductivity> The thermal conductivity is expressed by the following formula, and is calculated by measuring the thermal diffusivity, specific heat capacity, and density, respectively. [0088] <Temperature at the time of energization heating> As a result of measuring the temperature of graphite sheets No. 1 to 9 under the condition of energization heating with a radiation thermometer, it was confirmed that the temperature reached 2000 ° C. or higher. Specifically, it is within a temperature range of 2000 to 3000 ° C. [0089] Thermal conductivity = thermal diffusivity × specific heat capacity × density The thermal diffusivity is measured by Laser Pit of ADVANCE RIKO (stock), and the specific heat capacity is by a differential scanning calorimeter (DSC6220: Hitachi High-Technologies (stock)) For the measurement, the density refers to the mass and volume of the flakes, and the thermal conductivity of each graphite sheet produced as described above is calculated at a temperature of 23 ° C. The results are shown in Table 1. [Table 1] [0091] According to Table 1, the graphite sheet, which is the sheet-like graphite formed body of the present invention, has higher thermal conductivity than the comparative example, and can be efficiently produced in a short time. [0092] In the present invention, graphene oxide is used as a starting material, and sp 2 covalent bonds are efficiently formed in the entire formed body by applying electric heating, and the alignment is improved by pressurization, thereby , Can realize the previously unrealized graphene material can be layered to efficiently and efficiently produce a highly oriented graphite formed body; and this means: graphite can be used as a raw material of graphene oxide rich in the earth, Without impairing the original properties of the crystal, it can be processed into various forms depending on the application. [0093] Since the past, there have been many reports or patent documents regarding graphene oxide, and most of them focus on the excellent physical properties of single-layer graphene discovered in 2004. The present invention is different from this mainstream, but is based on the use of graphene oxide's solvent dispersing ability or the alignment ability due to high aspect ratio during molding, so as to efficiently produce industrially valuable high Insights on Aligned Graphite Shaped Body. In order to efficiently produce a highly oriented graphite molded body from graphene oxide, only a simple electric heating and pressing process is needed at first glance, and by using this shaped body, it is possible for the first time to show the high orientation graphite molded body. Excellent physical properties. The present invention can be said to be a manufacturing method that satisfies the moldability, alignment, and manufacturing efficiency of all materials required to produce a highly-aligned graphite molded body, and can be said to be extremely valuable in the industry. [Industrial Applicability] [0094] The manufacturing method of the graphite molded body of the present invention is a method for manufacturing a graphite molded body using graphene oxide as a raw material. It can provide a method that can be manufactured from graphene oxide in a short time and easily. A method for manufacturing a graphite molded body having a high thermal conductivity graphite molded body.