JP2012156202A - Graphene/polymer laminate and application of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide efficient and low-cost processes of fabricating a graphene/polymer laminate with excellent physical properties and smooth surfaces.SOLUTION: The method includes a graphene transfer process where at least one layer of a multilayer graphene 10 having multiple layers of graphenes formed on a metal substrate is cleaved between layers in the multilayer graphene 10, and laminated to a polymeric film 3.

Description

  The present invention relates to a graphene / polymer laminate and use thereof, for example, a method for producing a graphene / polymer laminate without using an etching process, and a laminate such as a transparent conductor produced by the production method. It is about.

  In recent years, graphene has various excellent electrical characteristics, thermal characteristics, and optical characteristics, and is expected to be used in a wide range of fields including the electronics field and the fuel cell field. In other words, graphene is a carbon material that is attracting attention both in Japan and overseas as a nanomaterial comparable to or exceeding that of carbon nanotubes.

  Conventionally, as a method for producing graphene, a CVD (Chemical Vapor Deposition) method, a chemical exfoliation method from graphite, a mechanical exfoliation method from graphite, and the like are used. In the CVD method, a gas such as methane is brought into contact with a substrate such as copper under a predetermined condition, so that one layer of graphene (hereinafter referred to as “single layer graphene”) is mainly formed on the substrate such as copper. It is a technique to form.

  Single-layer graphene formed using the CVD method is transferred to a polymer film, transferred together with the adhered copper, etc., and after transfer, the polymer is laminated with graphene by etching away the copper, etc. A film is obtained. As a technique for transferring single-layer graphene formed using a CVD method to a polymer film, for example, Non-Patent Document 1 discloses a graphene layer formed on a copper substrate by a thermal CVD method as a copper etching process. A method of transferring single-layer graphene to a polymer film by a roll-to-roll system including

  As a method for producing graphene without using the CVD method, for example, Non-Patent Document 2 shows a method for producing graphene by performing a heat treatment on an organic polymer compound thin film formed on a copper substrate. Has been.

Sukang Bae et.al., Roll-to-roll production of 30-inch graphene films for transparent electrodes, Nature Nanotechnology, Volume: 5, p.574-578, 2010 Zhengzong Sun et.al., Growth of graphene from solid carbon sources, Nature, Volume: 468, p.549-552, 2010

  However, in the method of producing graphene using the CVD method, single-layer graphene is mainly produced, and high-quality multi-layer graphene cannot be produced. In the CVD method, since the carbon source is sequentially stacked on the substrate, copper as a catalyst does not work on the carbon source stacked on the single-layer graphene. Therefore, the properties of the second and higher graphene layers are extremely bad. Because it becomes. When transferring single layer graphene to a polymer film for use as a transparent conductor, it is difficult to peel off the single layer graphene and the copper substrate, so after bonding the polymer film and the single layer graphene, Copper or the like needs to be removed by etching, and there is a problem that this etching process takes time and cost. Furthermore, there is a problem that etched copper or the like cannot be reused.

  On the other hand, no particularly excellent technique has been devised for the transfer method for transferring graphene produced by the method disclosed in Non-Patent Document 2 to a polymer film.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a method for producing single-layer graphene or multilayer graphene having excellent physical property values efficiently and at low cost, graphene / To provide a method for producing a polymer laminate and use thereof.

  In view of the above problems, the present inventors have intensively studied a method for producing single-layer graphene and multilayer graphene having excellent physical property values on a transparent polymer film without using an etching process. As a result, graphene formed on a metal substrate by a heat treatment method of an organic polymer compound has excellent physical property values not only in single-layer graphene but also in two or more layers of graphene. The present inventors have found that a single layer or a plurality of layers of graphene can be physically (mechanically) peeled from the obtained multiple layers of graphene, and have completed the present invention. Usually, when graphene is produced from graphite by physical exfoliation, it is not possible to determine at which part of graphite the exfoliation occurs. In particular, there is a problem that it can be obtained only as a graphite thin film (or graphene) having a different number of layers. However, surprisingly, in the method of the present invention, graphene having a constant number of layers can be peeled off at most peeling portions. This indicates that since the number of graphene layers formed on the metal is extremely small, the number of graphene layers to be peeled is also limited, and is excellent as a base material for peeling.

  Furthermore, as the metal substrate at this time, not only copper but also iron, nickel, chromium, or an alloy containing at least copper, iron, nickel, or chromium, oxides of these metals, or silicon oxide are effective. I also found that it can be used. That is, the basic principle of the present invention focuses on delamination between multiple layers of graphene, and after adhering an adhesive polymer film to the graphene layer, at least one of the multiple layers of graphene is peeled off between the layers. In other words, it has been uniquely found that a smooth graphene / polymer laminate having excellent physical properties can be produced.

  Here, the multi-layer graphene is easily peeled between layers, and the peeled graphene is smooth and has excellent physical properties. Further, according to the method of the present invention, it is not necessary to use an etching process, and a substrate such as copper that has not been etched can be reused.

  That is, in order to solve the above-described problem, the method for producing a graphene / polymer laminate according to the present invention includes at least one layer of multi-layer graphene formed on a metal substrate and including a plurality of graphene layers. It is characterized by including a graphene transfer process in which the film is peeled between the layers and transferred (attached) to a polymer film.

  According to the above configuration, even when the multilayer graphene is bonded to a substrate such as copper before peeling, copper or the like does not adhere to the graphene attached to the polymer film. This eliminates the need to use an etching process after the graphene is attached to the polymer film. Furthermore, after graphene is attached to the polymer film, unetched copper or the like can be reused.

  Further, in the method for producing a graphene / polymer laminate according to the present invention, the multilayer graphene forms a layer of an organic polymer compound formed on the metal substrate in a range of 800 ° C. or higher and 1700 ° C. or lower in the presence of hydrogen. It is preferable that it is obtained by heat treatment at the inner temperature.

  Thereby, the manufacturing method of the graphene / polymer laminated body of this invention can form multilayer graphene efficiently in the said graphene formation process.

  The metal substrate preferably includes copper, iron, nickel, chromium, silicon, an alloy containing at least one of these, or an oxide thereof, and a plurality of higher-quality graphene layers are formed on the metal substrate. In order to form it, it is preferable to heat-process at 800 degreeC or more as high temperature as possible. Considering the melting point of the substrate metal, 1000 ° C. for copper, 1500 ° C. for iron, 1400 ° C. for nickel, and 1700 ° C. for stainless steel are the maximum effective temperature ranges.

  In the graphene / polymer laminate manufacturing method of the present invention, in the graphene forming step of forming the multilayer graphene, a process of bringing a hydrogen gas flow into contact with the organic polymer compound is performed, and a flow rate of the hydrogen gas is increased. It is preferably in the range of 1 sccm or more and 100 sccm or less.

  Thereby, the manufacturing method of the graphene / polymer laminated body of this invention can form multilayer graphene efficiently in the said graphene formation process.

  In the method for producing a graphene / polymer laminate according to the present invention, the organic polymer compound has a substituent containing at least an oxygen atom, that is, selected from organic polymer compounds having at least an oxygen atom. Specifically, an organic polymer compound containing a substituent such as a hydroxyl group, a carbonyl group, or a carboxyl group is preferable.

  Thereby, the manufacturing method of the graphene / polymer laminated body of this invention becomes easy to form multilayer graphene in the said graphene formation process.

  In the method for producing a graphene / polymer laminate of the present invention, the metal substrate preferably has a surface roughness (Ra) of 0.01 μm or less.

  Accordingly, it is considered that the graphene / polymer laminate of the present invention can easily peel at least one layer of multilayer graphene between the layers of the multilayer graphene.

  In the graphene / polymer laminate manufacturing method of the present invention, in the graphene transfer step, an adhesive polymer film is pressure-bonded onto the multilayer graphene formed on the metal substrate, and then the It is preferable that at least one layer of the multilayer graphene is peeled off between the layers of the multilayer graphene and attached to the polymer film.

  Thereby, the manufacturing method of the graphene / polymer laminated body of this invention becomes easy to transcribe | transfer graphene to a polymer film in the said graphene transfer process.

  In the graphene / polymer laminate manufacturing method of the present invention, in the graphene transfer step, the roll-shaped polymer film is used and the roll-shaped polymer film is rotated, so that the multilayer graphene It is preferable that at least one layer is peeled off between the layers of the multilayer graphene and attached to the polymer film.

  Thereby, the manufacturing method of the graphene / polymer laminated body of this invention becomes easy to transcribe | transfer graphene to a polymer film in the said graphene transfer process.

  The graphene / polymer laminate of the present invention is characterized in that it can be produced by the above-described method for producing a graphene / polymer laminate.

  Thereby, the graphene / polymer laminate of the present invention can smooth the surface of the graphene.

  In the graphene / polymer laminate of the present invention, the polymer film is preferably transparent.

  Since graphene has transparency and electrical conductivity, the graphene / polymer laminate of the present invention becomes a transparent conductor when the polymer film is transparent. As a result, the graphene / polymer laminate of the present invention can be used as an alternative such as ITO (Indium Tin Oxide).

  In addition, the transparent conductor of the present invention is characterized in that it can be manufactured by the above-described graphene / polymer laminate manufacturing method.

  Since graphene is extremely thin and has high conductivity, the transparent conductor of the present invention has improved light transmittance. As a result, the transparent conductor of the present invention can be used as a substitute for ITO or the like.

  Moreover, the device of the present invention is characterized by including the transparent conductor.

  Thereby, the device of this invention is applicable to the apparatus provided with members, such as an electrode which consists of ITO.

  The method for producing a graphene / polymer laminate of the present invention, as described above, peels at least one layer of multilayer graphene having a plurality of graphene layers formed on a metal substrate between the multilayer graphene layers, It is a method including a graphene transfer step for attaching to a polymer film.

  Therefore, the method for producing a graphene / polymer laminate of the present invention can produce a graphene / polymer laminate having an excellent physical property value and a smooth surface efficiently and at low cost. There is an effect.

It is sectional drawing which shows the process of the manufacturing method of the graphene / polymer laminated body in one Embodiment of this invention. It is sectional drawing which shows the process of the manufacturing method of the graphene / polymer laminated body in one Embodiment of this invention.

  One embodiment of the present invention will be described in detail below, but the scope of the present invention is not limited to these explanations, and modifications other than the following exemplifications are made as appropriate without departing from the spirit of the present invention. Can be implemented.

(I) Method for Producing Graphene / Polymer Laminate in the Present Embodiment A method for producing a graphene / polymer laminate in the present embodiment comprises at least one layer of multilayer graphene formed on a metal substrate. It is a method including a graphene transfer process in which the film is peeled between the layers and attached to a polymer film.

  Further, the method for producing a graphene / polymer laminate in the present embodiment further includes a graphene forming step of forming the multilayer graphene, and in the graphene forming step, an organic polymer compound (carbon-containing polymer compound) ) Is preferably subjected to a treatment with hydrogen gas and a heat treatment.

  In the graphene / polymer laminate manufacturing method according to the present embodiment, in the graphene transfer step, an adhesive polymer film is pressure-bonded to the multilayer graphene, and then at least one of the multilayer graphenes is bonded to the multilayer graphene. It is characterized by being peeled off between graphene layers and affixed to the polymer film. At this time, the roll-shaped polymer film is further used, and the roll-shaped polymer film is rotated to peel at least one layer of the multilayer graphene between the layers of the multilayer graphene. It is preferable to paste.

<Graphene>
In this specification, graphene refers to a sheet having a thickness of one atom of carbon atoms in which benzene rings are two-dimensionally connected. Specifically, graphene is a two-dimensional crystal in the form of graphite, in which atoms are arranged according to the regular order of a hexagonal structure. The thickness of this sheet corresponds to the thickness of carbon atoms and consequently corresponds to a thickness of less than nanometers. Graphene is in the form of a planar hexagonal lattice, with each carbon atom bonded to three carbon atoms, thus leaving one of the four outer electrons used for chemical bonding in a free state. . As a result, these free electrons have high electrical conductivity because they can move along the crystal lattice.

  In this specification, “multilayer graphene” refers to one having a plurality of graphene layers, and can also be referred to as an ultrathin graphite film. Further, in this specification, “graphene / polymer laminate” refers to a mixture of at least one layer of graphene and a material other than graphene such as a polymer film. Examples of the “graphene / polymer laminate” include “graphene and polymer film laminate”.

<Graphene formation process>
In the graphene formation step of this embodiment, multilayer graphene is formed. Specifically, as shown in FIG. 1, the organic polymer compound 1 is disposed on the substrate 2 and processed under the following conditions to obtain the multilayer graphene 10. In FIG. 1, the multilayer graphene 10 is a two-layer graphene, but is not limited to this, and is included in the present embodiment as long as it is within the range of 2 or more and 20 or less, particularly 2 or more and 10 or less. It is preferable that The conditions for forming graphene according to the present embodiment will be described below.

"substrate"
In the graphene forming step of the present embodiment, the polymer compound is preferably placed on a metal substrate.

  The metal substrate used in this embodiment may be formed on a substrate containing silicon. As a substrate containing silicon, a crystalline silicon substrate, a polysilicon substrate, an amorphous silicon substrate, an epitaxial silicon substrate, a silicon dioxide substrate, a silicon carbide substrate, a silicon oxycarbide substrate, a silicon nitride substrate, a silicon carbonitride substrate (SiCN), silicon, A substrate containing oxygen, carbon, and fluorine (expressed as SiOCF), a silicon boronitride substrate, and the like can be given.

  The metals are copper (Cu), tungsten (W), nickel (Ni), iron (Fe), cobalt (Co), yttrium (Y), palladium (Pd), platinum (Pt), and gold (Au). , Molybdenum (Mo) and silver (Ag), any one pure metal, an alloy containing two or more of these, or a metal oxide thereof. The metal is particularly preferably copper, iron, nickel, or a metal oxide thereof.

《Organic polymer compound》
The “organic polymer compound” used in the present embodiment is preferably an organic polymer excellent in film forming ability and has a substituent containing at least an oxygen atom. Specific organic polymers include polymethyl methacrylate (PMMA, poly methyl methacrylate), polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyvinyl butyral, polymethacrylate, poly-L-lysine, sulfonated polystyrene, glycidyl modified. Exemplifying a polymer compound or copolymer having at least one selected from the group consisting of polyester, polyester, sulfonic acid-modified polyester, carboxylic acid-modified polyester, carboxymethyl cellulose, epoxy resin, saccharose, and derivatives thereof Can do. In order to perform N-doping, it is preferable to further contain a nitrogen-containing organic substance such as melamine, for example, to use a mixture of melamine and PMMA.

《Hydrogen gas》
The graphene formation step of the present embodiment is preferably performed in the presence of hydrogen, and more preferably performed in a hydrogen gas flow. In order to obtain two to ten layers of multilayer graphene, the hydrogen gas flow rate is preferably in the range of 1 sccm or more and 100 sccm or less, more preferably in the range of 2 sccm or more and 40 sccm or less, more preferably 3 sccm or more. , 20 sccm or less is particularly preferable.

《Gas other than hydrogen gas》
In the graphene formation step of this embodiment, a gas other than hydrogen gas, such as argon gas, nitrogen gas, and helium gas, may be mixed with hydrogen gas.

<Heat treatment>
Although the upper limit of the temperature of the heat treatment in the multilayer graphene forming step of the present embodiment is limited by the melting point of the metal substrate to be used, it is preferably 800 ° C. or higher for producing high-quality graphene, and as high as possible. More preferably. For example, 1000 ° C. for a copper substrate, 1500 ° C. for an iron substrate, 1400 ° C. for a nickel substrate, 1700 ° C. for a stainless steel substrate, 2600 ° C. for a molybdenum substrate, In some cases, the temperature is preferably 3000 ° C. From a practical point of view, copper, iron, nickel, stainless steel, silicon, or oxides of these metals are important, and considering this point, a desirable heating temperature range is 800 ° C to 1700 ° C.

<Other processing conditions>
In the graphene formation step of the present embodiment, control of the cooling rate after heating may be performed in addition to the above processing. High-quality graphene is formed by rapid cooling, and precipitation of carbon other than graphene (such as amorphous carbon) can be prevented. In order to obtain a large cooling rate, it is effective to separate graphene generated in the same atmosphere after heating from the heated portion.

<Graphene transfer process>
In the graphene transfer step of this embodiment, at least one layer of multilayer graphene having a plurality of graphene layers is peeled off between the multilayer graphene layers and attached to a polymer film. The conditions for graphene transfer and the like will be described below.

《Polymer film》
As the polymer film used in the present embodiment, polymethyl methacrylate, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyvinyl butyral, polymethacrylate, poly-L-lysine, sulfonated polystyrene, glycidyl-modified polyester, polyester, Examples thereof include a film containing a polymer compound or copolymer having at least one selected from the group consisting of sulfonic acid-modified polyester, carboxylic acid-modified polyester, carboxymethyl cellulose, epoxy resin, saccharose, and derivatives thereof.

  Here, in the present specification, the “polymer film” includes a polymer sheet containing the polymer compound or the copolymer.

  Moreover, it is preferable that the polymer film used for this embodiment is transparent. Since graphene has transparency, the graphene / polymer laminate of this embodiment becomes a transparent conductor when the polymer film is transparent. As a result, the transparent conductor can be used as a substitute for ITO (Indium Tin Oxide).

<Transcription method>
A method for transferring graphene to a polymer film will be described below with reference to FIG.

  The transfer of the multilayer graphene 10 to the polymer film 3 is performed by pressure-bonding (pressing) the polymer film 3 to the surface of the multilayer graphene 10. The surface of the polymer film 3 is preferably preliminarily improved in adhesion to the multilayer graphene 10 by applying a transfer agent such as an adhesive or polyimide, or performing an activation treatment such as an oxygen plasma treatment. . The adhesion force of the surface of the polymer film 3 is made weaker than the adhesion force between the substrate 2 and the multilayer graphene 10. Further, the adhesion of the surface of the polymer film 3 is made stronger than the interlayer adhesion between the multilayer graphenes 10. Thereby, at least one layer of the multilayer graphene 10 on the substrate 2 can be transferred to the polymer film 3 and taken out.

  When the polymer film 3 is in a roll shape, at least one layer of the multilayer graphene 10 can be transferred (attached) to the polymer film 3 by rotating the polymer film 3. .

  As an example of the transfer film, a polymer film having a two-layer structure composed of a thermosetting epoxy adhesive resin and a transparent polyester film can be exemplified.

  Specific examples of thermosetting epoxy adhesives include aromatic epoxy resin bisphenol A type (Epicoat 828) and alicyclic epoxy resins (for example, 3,4-epoxycyclohexyl methyl-3,4-epoxycyclohexylcarboxy). Rate (trade name: Celoxide 2021-P)) and the like. As these curing agents, acid anhydride curing agents are preferably used. It is more preferable to use an imidazole-based curing catalyst.

  The adhesive layer of the polymer film having such a structure can be pressure-bonded to the multilayer graphene formed on the substrate, the epoxy adhesive layer can be cured by infrared light from the polyester side, and the graphene layer can be transferred to the epoxy layer .

《Method using roll-shaped polymer film》
In the graphene / polymer laminate manufacturing method according to the present embodiment, in the graphene transfer step, the roll-shaped polymer film is used, and the roll-shaped polymer film is rotated, thereby rotating at least one of the multilayer graphenes. The layer is preferably peeled off between the graphene layers and attached to the polymer film.

<Substrate after processing in graphene transfer process>
The substrate after the treatment in the graphene transfer step can be reused in the method for producing the graphene / polymer laminate in the present embodiment. Specifically, graphene can be obtained by placing the organic polymer compound again on the substrate after the treatment and treating the substrate under the above-described conditions. At this time, before the organic polymer compound is disposed, the substrate surface may be heat-treated with a higher concentration of hydrogen gas to leave only the single-layer graphene, or the graphene layer may be completely removed.

(II) Configuration of graphene / polymer laminate in the present embodiment The graphene / polymer laminate in the present embodiment peels at least one layer of multilayer graphene having a plurality of graphene layers between the multilayer graphene layers, It is manufactured by a manufacturing method including a graphene transfer process that is attached to a polymer film. Moreover, it is preferable that the graphene / polymer laminated body in this embodiment is manufactured by the manufacturing method which further includes the graphene formation process which forms the said multilayer graphene.

  In the graphene / polymer laminate in the present embodiment, the polymer film is preferably transparent. Since graphene has transparency, when the polymer film is transparent, the graphene / polymer laminate in the present embodiment becomes a transparent conductor.

<Physical Properties of Graphene / Polymer Laminate in the Present Embodiment>
<< Surface roughness (Ra) >>
The surface roughness (Ra) of the metal substrate for producing graphene in this embodiment is preferably 0.01 μm or less, more preferably 0.002 μm or less, and particularly preferably 0.001 μm or less. preferable. When the surface roughness of the metal substrate is larger than 0.01 μm, the single layer or the multilayer graphene cannot be peeled from the multilayer graphene even by using the method of the present embodiment.

<< Transmissivity, surface resistance, peelability, etc. >>
The graphene in this embodiment is extremely good, and the transmittance (value obtained by subtracting the transmittance of the substrate) in the case of single-layer graphene is about 98%, and the surface resistance value per unit area is 1200Ω. Furthermore, the number of graphene layers exfoliated by the method of the present embodiment was uniform over the entire exfoliation surface, and was extremely excellent compared to the case of exfoliation from graphite crystals.

(III) Graphene / polymer laminate manufacturing apparatus in the present embodiment The graphene / polymer stack manufacturing apparatus in the present embodiment preferably mainly includes a heater, a vacuum pump, and a hydrogen flow control valve.

(IV) Configuration of transparent conductor and device having the same in this embodiment The transparent conductor (transparent conductive film) in the present embodiment includes at least one of the graphenes having a plurality of graphene layers. It is manufactured by a manufacturing method including a graphene transfer step, which is peeled off between layers and attached to a polymer film, and the polymer film is transparent.

  The transparent conductor in the present embodiment can be applied to an electrode such as a pixel electrode, a touch panel, an electromagnetic shield of a direct type LCD-TV, an inorganic EL electrode, an organic EL electrode, or the like as an alternative to ITO.

  Moreover, the device in this embodiment is provided with the said transparent conductor. The configuration other than the transparent conductor is not particularly limited, and may include a conventionally known member.

(V) Specific Example of Method for Producing Graphene / Polymer Laminate in This Embodiment Hereinafter, a graphene is produced using a PMMA thin film as a typical example of the method for producing a graphene / polymer laminate of the present invention. Take up the case and explain it more specifically. However, the method for producing the graphene / polymer laminate of the present invention is not limited to the following specific examples.

PMMA is applied on a copper (Cu) film by spin coating so as to have a thickness of about 100 nm. Copper is previously placed on the “SiO ₂ / Si substrate”. The “PMMA / Cu / SiO ₂ / Si substrate” thus obtained is heated at 800 ° C. for 10 minutes. At this time, PMMA is thermally decomposed under low pressure conditions in an “Ar / H ₂ reducing atmosphere”.

Thus, one layer of graphene (single layer graphene) can be formed on copper. This single layer graphene has a very good Raman spectrum. Specifically, for example, the “I (2D) / I (G) ratio” is about 4. The 2D line width is about 30 cm ⁻¹ . In this single layer graphene, 10 or more Raman spectra may be confirmed in 1 cm ⁻¹ square.

Further, under the condition of 1000 ° C., the same operation is performed by changing the flow rate of hydrogen (H ₂ ) using PMMA as a starting material and the flow rate of argon (Ar) at a constant 500 sccm.

  (A) When the flow rate of hydrogen is 50 sccm, only single-layer graphene can be formed. The resistance of the graphene sheet at this time is 1200Ω. The transmittance is 97.1%.

  (B) When the flow rate of hydrogen is 10 sccm, bilayer graphene can be formed. At this time, the transmittance of the graphene sheet is 94.3%.

  (C) When the flow rate of hydrogen is 3 to 5 sccm, several layers (about six layers) of graphene can be formed. At this time, the transmittance of the graphene sheet is 83%. That is, multilayer graphene can be formed by a slow hydrogen flow.

  According to the above (a) to (c), it is understood that the number of graphene layers can be controlled by the flow rate of hydrogen.

  As in the case of using PMMA, single-layer and multi-layer graphene can be formed by using polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyvinyl butyral, polymethacrylate, saccharose, etc. instead of PMMA. it can.

The Raman spectrum of single-layer graphene obtained from PMMA is confirmed at 10 or more locations per 1 cm ² of the sample. In this spectrum, two peaks most prominent is the 2D peak of G peak and 2,690Cm ^-1 of 1,580cm ^-1. The intensity ratio of I _2D / _{I G} is about 4. Moreover, half of the maximum value in the line width of the 2D peak is about 30 cm ⁻¹ . The D peak (˜1,350 cm ⁻¹ ) is the noise level.

Herein, the thickness of graphene obtained from PMMA can be controlled by changing the flow rate of argon (Ar) and hydrogen (H ₂ ) gas, ie single layer graphene, two layer graphene or several layers It shows that graphene can be produced. Typical thickness is assessed by the Raman spectrum and UV transmission in graphene. Two-layer graphene obtained from PMMA is obtained under conditions of 1000 ° C. when the flow rate of argon is 500 cm ³ STPmin ⁻¹ and the flow rate of hydrogen is 10 cm ³ STPmin ⁻¹ . In addition, several-layer graphene obtained from PMMA is obtained under conditions of 1000 ° C. when the flow rate of argon is 500 cm ³ STPmin ⁻¹ and the flow rate of hydrogen is 3 to 5 cm ³ STPmin ⁻¹ . When the flow rate of hydrogen increases to 50 cm ³ STPmin ⁻¹ or more, single-layer graphene is obtained. Single layer graphene exhibits 97.1% UV transmission at a wavelength of 550 nm. Single layer graphene has a sheet resistance (R _S ) of 1200Ω by using a transparent electrode material. The bilayer graphene exhibits 94.3% UV transmission at a wavelength of 550 nm. If several layers of graphene and 6 layers of graphene are evaluated, an ultraviolet transmittance of 83% is exhibited at a wavelength of 550 nm. The shape and position of the 2D peak is different between single-layer graphene, double-layer graphene, and several-layer graphene. Specifically, the shape of the 2D peak of single-layer graphene is one sharp peak, whereas the shape of the 2D peak of double-layer graphene and several-layer graphene is a peak split by the interaction of the graphene surface . The position of the G peak with respect to the 2D peak indicates the uniformity of the graphene film. When the intensity ratio of I _G / I _2D is less than 0.4, 95% or more is single-layer graphene. When the intensity ratio of I _G / I _2D is about 0.8, 85% or more is bilayer graphene.

  Hydrogen in the present invention functions as a reducing agent and as a carrier gas for transferring carbon atoms from PMMA. The slow flow of hydrogen will facilitate the synthesis of multilayer graphene.

Furthermore, the temperature can be changed according to the flow rate of “Ar / H ₂ ”. The quality of the graphene film is evaluated by the D / G peak ratio in the Raman spectrum analysis. The peak ratio of the graphene sheet obtained at 800 ° C. is less than 0.1, and the peak ratio of the graphene sheet obtained at 750 ° C. is ˜0.35. Thereby, in order to obtain graphene from PMMA, it can be said that 800 degreeC is a lower limit.

In addition, an oxide such as Ni or Si and a substrate of SiO ₂ having a thickness of 200 nm generate graphene when coated with PMMA. According to this Raman spectrum, it can be seen that Ni has an effect as a catalyst substrate in order to make PMMA a high-quality crystalline graphene material without a D peak of 1,350 cm ⁻¹ . Under the same conditions, neither graphene nor amorphous carbon is obtained on Si or SiO ₂ . This demonstrates that graphene was obtained from a thin film of Ni or Cu deposited (evaporated) on Si or SiO ₂ . Furthermore, multilayer graphene can be obtained even with metals such as iron, Ni, and stainless steel by changing the temperature and the hydrogen concentration. In iron, a multilayer graphene film can be produced at a high temperature of 1500 ° C., and when the flow rate of argon is 500 cm ³ STPmin ⁻¹ and the flow rate of hydrogen is 10 cm ³ STPmin ⁻¹ , the multilayer graphene of 5 to 10 layers Is formed. In addition, in nickel, multilayer graphene can be produced at 1400 ° C. At this time, when the flow rate of argon is 500 cm ³ STPmin ⁻¹ and the flow rate of hydrogen is 10 cm ³ STPmin ⁻¹ , four to eight layers of multilayer graphene can be manufactured.

  In conclusion, this document shows that using a solid carbon source, both initial graphene and doped graphene can be obtained in a controllable state in a one-step process. This serves as a supplement to the CVD method.

Thereafter, the graphene obtained in the graphene forming step is transferred to a polymer film. A PET film provided with a thermosetting transparent epoxy layer (aromatic bisphenol A type (Epicoat 828)) is pressure-bonded on 6-layer graphene formed on a copper substrate under the above conditions, heated at 120 ° C. for 1 hour, and then copper The curing agent used was 4-methylhexahydrophthalic anhydride / hexahydrophthalic anhydride, and the curing catalyst used was 2-ethyl-4-methylimidazole. Four layers of graphene were transferred to the substrate, but surprisingly, the graphene transferred onto the PET at this time was four layers over almost the entire surface, and was a very uniform graphene film with a surface resistance of 340Ω. / Cm ² , and the transmittance obtained by subtracting the transmittance of the substrate was approximately 90%.

The same peeling and transfer processes were performed for 6-layer graphene formed on an iron substrate, but the graphene transferred to the PET substrate was 2-layer graphene, the surface resistance was 700 Ω / cm ² , and the transmittance of the substrate The transmittance after subtracting was about 95%. In the case of an 8-layer substrate formed using a nickel substrate, four graphene layers were transferred, the surface resistance was 320 Ω / cm ² , and the transmittance after subtracting the transmittance of the substrate was 90%. In any case, the number of graphene layers transferred to the PET polymer film is almost constant, indicating that the method of the present invention is a very good method.

  When the polymer film is in a roll shape, the graphene can be transferred (attached) to the polymer film simultaneously by rotating and pressing the polymer film together with the roll.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  Since the present invention can be applied to a transparent conductor or the like, it can be used in a wide range of fields such as the electronics field and the fuel cell field.

1 Organic Polymer Compound 2 Substrate 3 Polymer Film 10 Multilayer Graphene

Claims (12)

A graphene transfer step, comprising: a graphene transfer step of peeling at least one layer of multilayer graphene having a plurality of graphene layers formed on a metal substrate between layers of the multilayer graphene and attaching the graphene to a polymer film A method for producing a polymer laminate.   The multilayer graphene is obtained by heat-treating an organic polymer compound layer formed on the metal substrate at a temperature in the range of 800 ° C. or higher and 1700 ° C. or lower in the presence of hydrogen. The method for producing a graphene / polymer laminate according to claim 1.   3. The graphene / polymer laminate according to claim 1, wherein the metal substrate has copper, iron, nickel, chromium, silicon, an alloy containing at least one of them, or an oxide thereof. Body manufacturing method. In the graphene forming step of forming the multilayer graphene, a process of bringing a hydrogen gas flow into contact with the organic polymer compound is performed.
The method for producing a graphene / polymer laminate according to any one of claims 1 to 3, wherein a flow rate of hydrogen gas is in a range of 1 sccm or more and 100 sccm or less.   The method for producing a graphene / polymer laminate according to any one of claims 2 to 4, wherein the organic polymer compound has a substituent containing at least an oxygen atom.   The graphene / polymer laminate according to any one of claims 1 to 5, wherein the metal substrate has a surface roughness (Ra) of 0.01 µm or less.   In the graphene transfer step, an adhesive polymer film is pressure-bonded onto the multilayer graphene formed on the metal substrate, and then at least one layer of the multilayer graphene is peeled off between the layers of the multilayer graphene. The graphene / polymer laminate according to claim 1, wherein the graphene / polymer laminate is attached to the polymer film. In the graphene transfer step, using the roll-shaped polymer film,
The roll-shaped polymer film is rotated so that at least one of the multilayer graphenes is peeled off between the multilayer graphene layers and attached to the polymer film. The method for producing a graphene / polymer laminate according to claim 1.   A graphene / polymer laminate, which can be produced by the method for producing a graphene / polymer laminate according to any one of claims 1 to 8.   The graphene / polymer laminate according to claim 9, wherein the polymer film is transparent.   A transparent conductor which can be produced by the method for producing a graphene / polymer laminate according to claim 1. A device comprising the transparent conductor according to claim 11.

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