JP2017171517A - Method for producing graphite film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a graphite film of high quality.SOLUTION: Provided is a method for producing a graphite film where a graphite film with a graphite structure is produced from a compound (A) in which condensation reaction occurs between the same molecules and/or between heterologous molecules by heating, where the compound (A) is heated in an area (I) whose temperature is controlled to a temperature T1°C, and thereafter, in an area (III) whose temperature is controlled to a temperature T3°C, the graphite film is formed on a substrate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a graphite film.

  Graphite is one of the allotropes of carbon, and is sometimes called graphite or graphite, has good electrical conductivity, high corrosion resistance, and excellent wear resistance.

  A layered film of one atomic layer constituting graphite, in which a carbon atom forms a sp2 bond in the same plane by a sp2 hybrid orbital to form a hexagon, and spreads in a plane like a honeycomb. The graphite film is called graphene.

  When a field effect transistor is manufactured using such a graphene film or a graphite film such as a small number of graphene films (about 2 to 10 layers of graphite film), very high mobility is observed.

  As a method for producing a graphite film, conventionally, a film forming method by CVD (chemical vapor deposition film forming method) and a peeling method have been reported.

  A method for producing a graphite film by a CVD film formation method (chemical vapor deposition film formation method) typically involves using a gas such as methane or acetylene as a raw material for the graphite film at an ultra-high temperature of about 1000 ° C. This is a method of forming a film while introducing it onto a substrate and causing a decomposition reaction or the like on the surface of the substrate. The current mainstream method for producing a graphite film by a CVD film-forming method is a method in which a film is formed by thermally decomposing methane gas on a metal substrate having catalytic performance such as Cu, and then transferred onto an arbitrary substrate. There is (for example, Non-Patent Document 1).

  However, in the CVD film-forming method, a problem that a dangerous gas such as methane or acetylene has to be used, a problem that an ultra-high temperature environment is necessary, and a raw material gas is thermally decomposed by the catalytic action of a metal substrate. In addition, there is a problem that the film cannot be formed on the insulating substrate and a problem that it is not easy to transfer the film to an arbitrary part. In addition, when trying to form a multilayer graphite film such as a small number of graphenes (about 2 to 10 layers of graphite film), the catalytic action of the metal substrate does not function sufficiently, and the raw material is sufficient to form the film. It is necessary to increase the amount of gas supply (for example, Non-Patent Document 2). However, if the supply amount of the source gas is very large, the graphite film may grow rapidly, and there is a problem that it is not easy to form a graphite film with the targeted number of layers.

  A method of producing a graphite film by a peeling method typically involves cleaving highly-oriented heat-fired graphite (HOPG) with an adhesive tape, and applying a clean graphite surface adhering to the adhesive tape to the surface of the substrate to be formed. This is a method of rubbing and transferring (for example, Non-Patent Document 3). According to the peeling method, a high-quality graphite film can be obtained by using a high-quality highly-oriented heat-fired graphite. However, in the peeling method, there is a problem that in principle reproducibility is poor, a problem that a graphite film of an arbitrary size cannot be produced at an arbitrary position, and a problem that it is difficult to increase the area of the obtained graphite film. .

  In view of the above problems, a technique for forming a graphite film by blowing a hydrocarbon gas decomposed in advance onto the substrate surface has been reported (Patent Document 1). According to this technique, a gas having the same reactivity can always be sprayed, so that film formation control is relatively easy. However, there still remains a problem that a dangerous gas such as methane and acetylene has to be used, and an extremely high temperature environment is necessary.

  Recently, as a technique for forming a graphite film without using a flammable gas and without requiring ultra-high temperature conditions, a composition containing a plurality of reactive compounds is applied to the substrate surface by a liquid phase process. However, after that, by firing, a redox reaction occurs in the composition, and a technique for forming a graphite film on a substrate has been reported (Patent Document 2). However, since this technique uses a redox reaction by a plurality of reactive compounds, chemical reaction by-products and reaction catalysts exist in the graphite film, and these are fatal impurities. Therefore, there is a problem that a high quality graphite film cannot be obtained.

J. et al. Phys. : Condens. Matter, 9, 1-20 (1997). Appl. Phys. Lett. , Vol. 64, 842-844 (1994). Science, vol. 306, 666-669 (2004). JP 2010-269944 A JP 2013-023746 A

  An object of the present invention is to provide a method for forming a high-quality graphite film.

The method for producing a graphite film of the present invention includes:
A method for producing a graphite film having a graphite structure from a compound (A) that undergoes a condensation reaction between the same molecules and / or different molecules by heating,
After heating the compound (A) in the area (I) adjusted to a temperature T1 ° C., the graphite film is formed on the substrate in the area (III) adjusted to a temperature T3 ° C.

  In one embodiment, between the area (I) and the area (III), there is an area (II) whose temperature is adjusted to a temperature T2 ° C., and T1 <T2.

  In one embodiment, the T1 is lower than the decomposition temperature of the compound (A), and the T2 is higher than the decomposition temperature of the compound (A).

  According to the present invention, a method for forming a high-quality graphite film can be provided.

FIG. 1 is a schematic view of one embodiment of the apparatus for producing a graphite film of the present invention. 2 is a Raman spectrum chart obtained in Example 1. FIG. FIG. 3 is a Raman spectrum chart obtained in Example 2. 4 is a Raman spectrum chart obtained in Example 3. FIG. FIG. 5 is a Raman spectrum chart obtained in Example 4. 6 is a Raman spectrum chart obtained in Example 5. FIG. FIG. 7 is a Raman spectrum chart obtained in Comparative Example 1. FIG. 8 is a Raman spectrum chart obtained in Comparative Example 2. FIG. 9 is a Raman spectrum chart obtained in Comparative Example 3. FIG. 10 is a Raman spectrum chart obtained in Comparative Example 4.

  “Heating” in the present invention can employ heating by any appropriate means as long as the effects of the present invention are not impaired. Examples of such “heating” include heating in a baking furnace, heating on a hot plate, and heating by irradiation with a microwave or the like.

≪≪Compound (A) ≫≫
The compound (A) undergoes a condensation reaction between the same molecules and / or between different molecules by heating.

  The compound (A) may be one type of compound or two or more types of compounds.

<Representative Embodiment of Compound (A) (Embodiment 1)>
A representative embodiment (embodiment 1) of the compound (A) is an aromatic compound that decomposes by heating to generate a radical on the aromatic ring. The aromatic compound in which radicals are generated on the aromatic ring causes a condensation reaction between the same molecule and / or between different molecules, and becomes a graphite film having a graphite structure.

  The aromatic compound that decomposes by heating and generates radicals on the aromatic ring is preferably an aromatic compound that generates gas by heating.

As the aromatic compound that generates gas by heating, any appropriate aromatic compound may be adopted as long as it is an aromatic compound and generates gas by heating. Such a gas is preferably at least one selected from CO, CO ₂ , N ₂ , O ₂ , H ₂ and NO ₂ .

As an aromatic compound that generates CO and / or CO ₂ by heating, for example, an aromatic compound having a “—C (═O) —” and / or “—O—C (═O) —” structure (for example, , Aromatic ketone derivatives, aromatic ester derivatives, acid anhydrides, and the like.

The aromatic compound which generates CO and / or CO ₂ by heating, for example, the following compounds.

Examples of the aromatic compound that generates N ₂ by heating include an aromatic compound having an “—NH—NH—” structure, an “—N═N—” structure, and an “—N ₃ ” structure (for example, an aromatic compound). Azo compounds, aromatic azide compounds, triazole substituted aromatic compounds, tetrazole substituted aromatic compounds, triazine or derivatives thereof, tetrazine or derivatives thereof, aromatic hydrazine derivatives, and the like.

The aromatic compound that generates N ₂ by heating, for example, the following compounds. In the following compounds, R represents a hydrogen atom or an alkyl group, aryl group, or heteroaryl group which may have a substituent.

The aromatic compound that generates an O ₂ by heating, for example, - an aromatic compound having an "O-O-" structure (e.g., an aromatic carbon oxides, and aromatic peroxides) and the like.

The aromatic compound that generates an O ₂ by heating, for example, the following compounds. In the following compounds, R represents a hydrogen atom or an alkyl group, aryl group, or heteroaryl group which may have a substituent.

Examples of the aromatic compound that generates H ₂ by heating include a condensed polycyclic aromatic compound having a “—CH ₂ —” structure (eg, a phenalene compound).

The aromatic compound that generates and H ₂ by heating, for example, the following compounds.

The aromatic compound which generates NO ₂ by heating, for example, - aromatic compounds with "NO _2" structure (such as aromatic nitro compounds), and the like.

The aromatic compound which generates NO ₂ by heating, for example, the following compounds.

An aromatic compound that decomposes by heating to generate a radical on the aromatic ring has decomposability by heating, and at least a part of the skeleton is separated and decomposed to cause gas molecules (preferably CO, CO ₂ , N ₂ , O ₂ , H ₂ , NO ₂ ) is generated, and a radical is generated on the remaining aromatic ring. By using such an aromatic compound, a reaction by only its own decomposition occurs without the need for a reaction catalyst, so that a by-product of a chemical reaction or a reaction catalyst exists in the graphite film and is fatal. Therefore, it is possible to obtain a higher quality graphite film. Further, by using such an aromatic compound, a graphite film can be obtained in a relatively mild temperature environment without using a combustible gas. In addition, since such aromatic compounds have high reactivity that does not require catalytic action, they are not easily affected by the substrate on which the graphite film is formed, and any number of layers on any part of the surface of any substrate. Can be formed into a film.

<Representative Embodiment of Compound (A) (Embodiment 2)>
A representative embodiment (Embodiment 2) of the compound (A) is a compound in which one neutral molecule is formed from two or more groups by a condensation reaction and is eliminated. In this Embodiment 2, the case where one compound has 2 or more types of groups may be used, or the case where each group of 2 or more compounds is combined to form 2 or more types of groups It may be. Such a compound (A) causes a condensation reaction between the same molecules and / or between different molecules to form a graphite film having a graphite structure.

As the condensation reaction, any suitable condensation reaction may be employed as long as it is a condensation reaction in which one neutral molecule is formed from two or more groups and eliminated. obtain. As such a condensation reaction, for example,
(A) a condensation reaction in which H ₂ O is formed and eliminated from an —H group and an —OH group,
(B) a condensation reaction in which ROH is formed and eliminated from an —H group and an —OR group (R is any appropriate substituted or unsubstituted alkyl group);
(C) a condensation reaction in which HX is formed and eliminated from a —H group and a —X group (X is halogen or CN);
(D) a condensation reaction in which NH ₃ is formed and eliminated from the —H group and —NH ₂ group,
(E) a condensation reaction in which RNH ₂ is formed and eliminated from a —H group and a —NHR group (R is any appropriate substituted or unsubstituted alkyl group);
(F) Condensation reaction due to elimination and formation of R ¹ R ² NH from —H group and —NR ¹ R ² group (R ¹ and R ² are any appropriate substituted or unsubstituted alkyl group) ,
(G) a condensation reaction in which H ₂ S is formed and eliminated from the —H group and the —SH group;
(H) a condensation reaction in which RSH is formed and eliminated from the —H group and —SR group (R is any appropriate substituted or unsubstituted alkyl group);
(I) a condensation reaction in which RCOOH is formed and eliminated from the —H group and —OOCR group (R is any suitable substituted or unsubstituted alkyl group);
(J) a condensation reaction in which H ₂ SO ₃ is formed and eliminated from the —H group and —OSO (OH) group,
(K) a condensation reaction in which RSO ₂ (OH) is formed and eliminated from —H group and —OSO ₂ R group (R is any suitable substituted or unsubstituted alkyl group);
(L) a condensation reaction in which ROSO ₃ H is formed and eliminated from a —H group and a —OSO ₂ (OR) group (R is any suitable substituted or unsubstituted alkyl group),
(M) a condensation reaction in which H ₂ SO ₄ is formed and eliminated from the —H group and —OSO ₂ (OH) group,
Etc.

A typical example of the condensation reaction is a condensation reaction (above (a)) in which H ₂ O is formed from an —H group and an —OH group and eliminated.

  One embodiment of the compound (A) in Embodiment 2 (sometimes referred to as Embodiment (X)) is a compound (a1) having a skeleton consisting of one carbon six-membered ring structure or two or more carbons. Compound (a2) having a skeleton in which a 6-membered ring structure is bonded and / or condensed, wherein half of the number of substituents not contributing to the structure formation of the skeleton is an —OH group, and the other half is —H It is a group.

In the embodiment (X),
(I) When the compound (A) is a compound (a1) having a skeleton composed of one carbon 6-membered ring structure,
(Ii) When the compound (A) is a compound (a2) having a skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed,
Either of the two cases can be taken.

  In the embodiment (X), the “substituent that does not contribute to the structure formation of the skeleton” refers to the “skeleton composed of one carbon 6-membered ring structure” in the case of (i) above or the case of (ii) above. The “substituent which does not contribute to the structure formation of the skeleton of“ a skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed ””. For example, in the case of (i) above, when the compound (a1) having a skeleton composed of one carbon six-membered ring structure is represented by the following chemical formula (a1-1), one carbon six-membered ring structure Substituents that do not contribute to the structure formation of the skeleton consisting of 6 are —OH groups and 6 —H groups, and a compound (a1) having a skeleton consisting of one carbon 6-membered ring structure will be shown later. In the case of being represented by the chemical formula (a1-2), the substituents that do not contribute to the formation of a skeleton composed of one carbon six-membered ring structure are three —OH groups and three —H groups. Further, for example, in the case of (ii) above, the compound (a2) having a skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed is represented by the following chemical formula (a2-1) Substituents that do not contribute to the formation of a skeleton in which two or more carbon six-membered ring structures are bonded and / or condensed are six —OH groups and six —H groups.

  In Embodiment (X), half of the number of substituents that do not contribute to the structure formation of the skeleton of the compound (a1) having a skeleton consisting of one carbon six-membered ring structure is an —OH group; Half of the number of substituents that do not contribute to the structure formation of the skeleton of the compound (a2) having a skeleton in which half is a -H group and two or more carbon 6-membered ring structures are bonded and / or condensed -OH group, and the other half is -H group. By having such a substituent structure, the compound (A) can efficiently form a graphite structure while being effectively dehydrated between the same molecules and / or between different molecules by heating.

  As the compound (A) that can be employed in the embodiment (X), the compound (a1) having a skeleton composed of one carbon 6-membered ring structure or two or more carbon 6-membered ring structures are bonded and / or condensed. The compound (a2) having the above skeleton, in which half of the number of substituents that do not contribute to the structure formation of the skeleton is an —OH group and the other half is a —H group, Any appropriate compound can be adopted as long as the effect is not impaired. Examples of such a compound (A) include the following compounds.

  Another embodiment of the compound (A) in Embodiment 2 (sometimes referred to as Embodiment (Y)) is the compound (a1) having a skeleton consisting of one carbon 6-membered ring structure and / or 2 Two or more compounds selected from compounds (a2) having a skeleton in which at least one carbon 6-membered ring structure is bonded and / or condensed, and the substituents that do not contribute to the structure formation of the skeleton of the compound (a1) The half of the sum of the number and the number of substituents not contributing to the structure formation of the skeleton of the compound (a2) is an —OH group, and the other half is an —H group.

In the embodiment (Y),
(I) When the compound (A) is composed of two or more compounds selected from the compound (a1) having a skeleton composed of one carbon 6-membered ring structure,
(Ii) When the compound (A) is composed of two or more compounds selected from the compound (a2) having a skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed,
(Iii) In the compound (A), one or more selected from the compound (a1) having a skeleton composed of one carbon six-membered ring structure and two or more carbon six-membered ring structures are bonded and / or condensed. When composed of one or more compounds selected from compounds (a2) having a skeleton,
Any of the following three cases can be taken.

  In the embodiment (Y), “the total number of substituents not contributing to the structure formation of the skeleton of the compound (a1) and the number of substituents not contributing to the structure formation of the skeleton of the compound (a2)” It has the following meaning. That is, in the case of (i) above, the number of substituents that do not contribute to the structure formation of the skeleton of the “skeleton consisting of one carbon 6-membered ring structure” in each of two or more kinds of compounds (a1), It means the total number. In the case of (ii) above, the substitution that does not contribute to the structure formation of the skeleton of the “skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed” in each of the two or more compounds (a2) This means the total number of groups. In the case of (iii) above, the number of substituents that do not contribute to the structure formation of the “skeleton having one carbon 6-membered ring structure” in each of the one or more compounds (a1) and one kind The total number of substituents not contributing to the structure formation of the skeleton of the “skeleton in which two or more carbon 6-membered ring structures are bonded and / or condensed” in each of the above compounds (a2) is added up. Means number.

  In the embodiment (Y), for example, in the case of (i) above, when two or more compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-6), the chemical formula (a1 Substituents that do not contribute to the formation of a skeleton composed of one carbon 6-membered ring structure of the compound represented by −5) are two —OH groups and four —H groups, and are represented by the chemical formula (a1 Substituents that do not contribute to the structure formation of a skeleton composed of one carbon six-membered ring structure of the compound represented by -6) are four —OH groups and two —H groups, and their total Are 6 —OH groups and 6 —H groups. For example, in the case of (iii) above, one or more compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-7), and one or more compounds (a2) are In the chemical formula (a2-3), two substituents that do not contribute to the formation of a skeleton composed of one carbon 6-membered ring structure of the compound represented by the chemical formula (a1-5) There are 6 substituents that are —OH group and 4 —H groups, and do not contribute to the formation of the skeleton composed of one carbon 6-membered ring structure of the compound represented by the chemical formula (a1-7). -OH group, and two or more substituents that do not contribute to the formation of a skeleton in which two or more carbon 6-membered ring structures of the compound represented by the chemical formula (a2-3) are bonded and / or condensed -OH group and 6 -H groups.

  By using such a compound (A), a reaction due to its own dehydration occurs without the need for a reaction catalyst, so that a by-product of the chemical reaction or a reaction catalyst exists in the graphite film. It can suppress becoming a fatal impurity, and a higher quality graphite film can be obtained. Moreover, by using such a compound (A), a graphite film can be obtained in a relatively mild temperature environment without using a combustible gas. Further, since such a compound (A) has high reactivity that does not require a catalytic action, it is hardly affected by the substrate on which the graphite film is formed, and an arbitrary layer is formed on an arbitrary portion of the surface of an arbitrary substrate. The film can be formed with a number.

≪≪Method for producing graphite film≫≫
The method for producing a graphite film of the present invention is a method for producing a graphite film having a graphite structure from a compound (A), wherein the compound (A) is heated in an area (I) adjusted to a temperature T1 ° C. Thereafter, the graphite film is formed on the substrate in the area (III) where the temperature is adjusted to T3 ° C. According to such a manufacturing method, a high quality graphite film can be formed.

  The temperature T1 ° C. adjusted in the area (I) may be a substantially constant value or a temperature within a certain range.

  The temperature T3 ° C. adjusted in the area (III) may be a substantially constant value or a temperature within a certain range.

  The method for producing a graphite film of the present invention is preferably a gas phase process.

  The method for producing a graphite film of the present invention is preferably carried out under an inert gas stream under a vacuum, and more preferably under an inert gas stream. When the method for producing a graphite film of the present invention is carried out under an inert gas flow, the air flow is preferably an air flow directed from the area (I) side to the area (III) side. A typical example of the inert gas is nitrogen gas. When the method for producing a graphite film of the present invention is performed under vacuum, vacuum suction is preferably performed from the area (I) side toward the area (III) side.

  When the method for producing a graphite film of the present invention is carried out under an inert gas stream, the velocity of the air stream is preferably 0.1 L / min to 100 L / min, more preferably 0.5 L / min to 70 L. / Min, more preferably 1 L / min to 50 L / min, and particularly preferably 5 L / min to 30 L / min. When the method for producing a graphite film of the present invention is carried out under an inert gas stream, a higher quality graphite film can be formed if the velocity of the air stream is within the above range.

  Any appropriate substrate can be adopted as long as the substrate used in the area (III) is a substrate on which a graphite film can be formed as long as the effect of the present invention is not impaired. Examples of such a substrate include a nickel substrate and a silicon substrate.

  In the method for producing a graphite film of the present invention, preferably, the area (II) whose temperature is adjusted to a temperature T2 ° C. is provided between the area (I) and the area (III), and T1 <T2. With such a configuration, a higher quality graphite film can be formed.

  FIG. 1 is a schematic view of one embodiment of the apparatus for producing a graphite film of the present invention. In FIG. 1, the reaction tube 1000 passes through three zones of area (I) 100, area (II) 200, and area (III) 300. In the reaction tube 1000, an inert gas flows as an air flow 10 from the area (I) 100 side toward the area (III) 300 side. In the reaction tube 1000 in the area (I) 100, the compound (A) 30 placed on the reaction vessel 20 is present. The substrate 40 is disposed in the reaction tube 1000 in the area (III) 300. In the area (I) 100, the compound (A) 30 in the reaction tube 1000 is sublimated by being heated to a temperature T1 ° C., and moves in the reaction tube 1000 to the area (II) 200 together with the airflow 10. In the reaction tube 1000 in the area (II) 200, the sublimated compound (A) 30 is decomposed by being heated to a temperature T2 ° C., and subsequently, in the reaction tube 1000, together with the air flow 10, the area (III) Move to 300. Thereafter, a graphite film is formed on the substrate 40 by heating to a temperature T3 ° C. in the reaction tube 1000 in the area (III) 300.

  The heating temperature T1 ° C. in the area (I) and the heating temperature T2 ° C. in the area (II) are preferably in a relationship of T1 <T2. By having such a relationship, a higher quality graphite film can be formed.

  T1 is preferably less than the decomposition temperature of the compound (A). In addition, when compound (A) is 2 or more types of compounds, T1 is preferably lower than the lowest decomposition temperature among the respective decomposition temperatures of the 2 or more types of compounds. T1 is less than the decomposition temperature of compound (A) (when compound (A) is two or more compounds, T1 is less than the lowest decomposition temperature among the respective decomposition temperatures of the two or more compounds). As a result, a higher quality graphite film can be formed.

  T1 can be set to any appropriate value depending on the type of the compound (A). Specifically, such T1 is preferably 100 ° C to 500 ° C, more preferably 130 ° C to 400 ° C, still more preferably 150 ° C to 350 ° C, and particularly preferably 170 ° C to 300 ° C. ° C. If T1 is within the above range, a higher quality graphite film can be formed.

  T2 is preferably equal to or higher than the decomposition temperature of the compound (A). In addition, when compound (A) is 2 or more types of compounds, T2 is preferably higher than or equal to the highest decomposition temperature among the respective decomposition temperatures of the 2 or more types of compounds. T2 is equal to or higher than the decomposition temperature of compound (A) (when compound (A) is two or more compounds, T2 is equal to or higher than the highest decomposition temperature among the respective decomposition temperatures of the two or more compounds). As a result, a higher quality graphite film can be formed.

  T2 can be set to any appropriate value depending on the type of compound (A). Specifically, such T2 is preferably 150 ° C to 700 ° C, more preferably 170 ° C to 600 ° C, still more preferably 200 ° C to 500 ° C, and particularly preferably 230 ° C to 400 ° C. ° C. If T2 is within the above range, a higher quality graphite film can be formed.

  T3 is a heating temperature for forming a graphite film on the substrate in the area (III), specifically, preferably 150 ° C. to 700 ° C., more preferably 200 ° C. to 600 ° C., More preferably, it is 250 to 550 degreeC, Most preferably, it is 300 to 500 degreeC. If T3 is within the above range, a higher quality graphite film can be formed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”. In this specification, “mass” may be read as “weight”.

<3-zone firing>
The three-zone firing was performed using the following three-zone firing apparatus and settings.
Three-zone baking apparatus: KTF647 manufactured by Koyo Thermo System Co., Ltd. was used, and the area (I), area (II), and area (III) were sequentially formed from the entrance side.
Firing conditions: The heaters in each area were set so that the temperature could be adjusted independently.

<TG-DTA analysis>
The TG-DTA analysis was performed with the following equipment and conditions.
Measuring device: Suggested thermo-thermogravimetric simultaneous measuring device (Seiko Instruments, TG / DTA6200)
Measurement conditions: nitrogen atmosphere conditions, temperature rising rate 5 ° C./min. The sublimation temperature was the temperature at 1% weight loss and the maximum temperature of the decomposition temperature dTA.

<Raman spectroscopy>
The Raman spectroscopic analysis was performed with the following apparatus and conditions.
Measuring device: Micro Raman (JASCO NRS-3100)
Measurement conditions: 532 nm laser used, objective lens 20 times, CCD capture time 1 second, total 64 times (resolution = 4 cm-1)
If the thin layer graphite structure exists, (around 1600 cm ^-1) G bands specific to graphite structure, (around 1350 cm ^-1) D band characteristic G 'band graphite thin layer (2700 cm around ^-1), A D + D ′ band (near 2900 cm ⁻¹ ) and a 2D ′ band (near 3200 cm ⁻¹ ) are observed. The band named G is a peak derived from graphite, and the band named D is a peak derived from defects in graphite. Therefore, it can be said that the band named G has higher strength and sharpness is a cleaner graphite, and the band named D is cleaner graphite as the strength is lower.

[Example 1]
Hexahydroxybenzene trisoxalate (HBTO, synthesized by the method described in JP-A-2016-269984, sublimation temperature estimated by TG-DTA is 290 ° C., decomposition temperature is 350 ° C.): 100 mg is put in a quartz boat, It was placed in the area (I) of the quartz tube installed in the three-zone firing furnace. A nickel substrate was placed in the area (III) of the quartz tube, vacuumed with a rotary pump, and then replaced with nitrogen three times. After nitrogen substitution, while flowing nitrogen at a flow rate of 10 L / min from area (I) side to area (III) side, area (I) is 300 ° C., area (II) is 500 ° C., area (III) Was heated to 300 ° C. After being left for 15 minutes in the heated state, after cooling, the nickel substrate was taken out and the graphite film on the surface was evaluated by Raman analysis (FIG. 2). As shown in FIG. 2, a band peculiar to the graphite film (especially thin graphite) was observed.

[Example 2]
The method described in Example 1 except that hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd., sublimation temperature estimated by TG-DTA is 180 ° C., decomposition temperature is 240 ° C.) is used instead of hexahydroxybenzene trisoxalate. The same operation was performed. The surface graphite film was evaluated by Raman analysis (FIG. 3). As shown in FIG. 3, a band specific to the graphite film (particularly a thin layer of graphite) was observed.

Example 3
As described in Example 1, except that phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., sublimation temperature estimated by TG-DTA is 200 ° C., decomposition temperature is 330 ° C.) is used instead of hexahydroxybenzene trisoxalate. The same operation as the method was performed. The surface graphite film was evaluated by Raman analysis (FIG. 4). As shown in FIG. 4, a band peculiar to a graphite film (especially a thin layer of graphite) was observed.

Example 4
The same operation as that described in Example 2 was performed except that the area (I) was heated to 200 ° C., the area (II) was heated to 350 ° C., and the area (III) was heated to 500 ° C. The surface graphite film was evaluated by Raman analysis (FIG. 5). As shown in FIG. 5, a band peculiar to a graphite film (particularly a thin layer of graphite) was observed, and a particularly beautiful graphite structure was achieved (D + D ′, 2D ′ bands were small).

Example 5
The same operation as that described in Example 3 was performed except that area (I) was heated to 250 ° C., area (II) was heated to 350 ° C., and area (III) was heated to 500 ° C. The surface graphite film was evaluated by Raman analysis (FIG. 6). As shown in FIG. 6, a band peculiar to the graphite film (especially a thin layer of graphite) was observed, and a particularly beautiful graphite structure was achieved (the G / D ratio was large and the band named D was small).

[Comparative Example 1]
HBTO was dissolved in dehydrated acetone (Wako Pure Chemical Industries) (20 wt% solution), and the solution was applied to a cleaned nickel substrate with a spin coater (2000 rpm, 30 s). This coated substrate was baked at 350 ° C. for 2 hours in a nitrogen atmosphere on a hot plate. The surface graphite film was evaluated by Raman analysis (FIG. 7). As shown in FIG. 7, bands (G and D bands) peculiar to the graphite film were observed. However, since the bands are broad and the G ′, D + D ′, and 2D ′ bands overlap with each other, they are amorphous. It was found that there were many components and a clean graphite structure could not be formed.

[Comparative Example 2]
Phloroglucinol was dissolved in dehydrated acetone (Wako Pure Chemical Industries) to prepare a 0.1% solution. This solution was applied to an aluminum substrate and baked at 500 ° C. in a nitrogen atmosphere. The surface graphite film was evaluated by Raman analysis (FIG. 8). As shown in FIG. 8, bands (G and D bands) peculiar to the graphite film were observed. However, since the bands are broad and the G ′, D + D ′, and 2D ′ bands overlap with each other, they are amorphous. It was found that there were many components and a clean graphite structure could not be formed.

[Comparative Example 3]
As a method simulating simple CVD, hydroquinone was deposited on a nickel substrate heated to 350 ° C. in advance by vapor deposition under a nitrogen atmosphere. The surface graphite film was evaluated by Raman analysis (FIG. 9). As shown in FIG. 9, bands (G and D bands) peculiar to the graphite film were observed. However, since the bands are broad and the G ′, D + D ′, and 2D ′ bands overlap with each other, they are amorphous. It was found that there were many components and a clean graphite structure could not be formed.

[Comparative Example 4]
The same operation as that described in Comparative Example 3 was performed except that phloroglucinol was used instead of hydroquinone. The surface graphite film was evaluated by Raman analysis (FIG. 10). As shown in FIG. 10, bands peculiar to the graphite film (G and D bands) were observed. However, since the bands were broad and the G ′, D + D ′, and 2D ′ bands overlapped with the broad, they were amorphous. It was found that there were many components and a clean graphite structure could not be formed.

  The graphite film obtained by the production method of the present invention can be used for, for example, a corrosion resistance, abrasion resistance and lubricity protective film, and a field effect transistor.

Claims (3)

A method for producing a graphite film having a graphite structure from a compound (A) that undergoes a condensation reaction between the same molecules and / or different molecules by heating,
After heating the compound (A) in the area (I) adjusted to a temperature T1 ° C., the graphite film is formed on the substrate in the area (III) adjusted to a temperature T3 ° C.
A method for producing a graphite film.   2. The method for producing a graphite film according to claim 1, wherein the area (II) is adjusted to a temperature T2 ° C. between the area (I) and the area (III), and T1 <T2. The method for producing a graphite film according to claim 2, wherein the T1 is lower than the decomposition temperature of the compound (A) and the T2 is equal to or higher than the decomposition temperature of the compound (A).

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